CN103155038A - Method of manufacturing glass blank for magnetic recording medium glass substrate, magnetic recording medium glass substrate manufacturing method, magnetic recording medium manufacturing method, and device for manufacturing glass blank for magnetic recording medium glass substrate - Google Patents

Abstract

To achieve improvement in evenness, provided are a method of manufacturing a glass blank for a magnetic recording medium glass substrate, and a magnetic recording medium glass substrate manufacturing method, a magnetic recording medium recording method, and a device for manufacturing a glass blank for a magnetic recording medium glass substrate, which employ said method of manufacturing a glass blank for a magnetic recording medium glass substrate, wherein: a pair of press-forming molds, which are positioned in opposition in the horizontal direction upon a piece of molten glass, and having effectively identical press-forming faces and press-forming face temperatures, are brought into approximately simultaneous contact with the piece of molten glass, press-forming same, producing a glass sheet; and the continuous time of the pressing of the glass sheet is controlled such that, upon extracting the glass sheet after sustained pressing thereof by the pair of molds, the evenness of the glass blank is 10[mu]m or less.

Description

The magnetic recording media glass substrate manufacture method of glass blank, the manufacture method of magnetic recording media glass substrate, the manufacture method of magnetic recording media and the manufacturing installation that the magnetic recording media glass substrate is used glass blank

Technical field

The present invention relates to the manufacture method of the magnetic recording media glass substrate manufacture method of glass blank, magnetic recording media glass substrate, the manufacture method of magnetic recording media and the manufacturing installation that the magnetic recording media glass substrate is used glass blank.

Background technology

as the mode of making magnetic recording media glass substrate (magnetic disc substrate), enumerate representativity: the mode that make through utilizing a pair of stamping forming die to carry out the drawing operation of drawing to fused glass block (1) (below, be sometimes referred to as " impact style ", with reference to patent documentation 1～3), and (2) will be through utilizing floating method (float method), the foliated glass of the formation such as glass tube down-drawing (down-draw method) cut off the mode that is processed into discoid operation and makes (below, be sometimes referred to as " foliated glass cut-out mode ", with reference to patent documentation 4).

In the illustrated existing foliated glass cut-out mode of patent documentation 4, after process is processed into foliated glass discoid disk manufacturing procedure, implement grinding process (slightly grinding processing) and polishing process (lappingout processing) as grinding step, thereby obtain the magnetic recording media glass substrate.Yet, in the foliated glass cut-out mode shown in patent documentation 4, disclose as grinding step and only implemented polishing process (lappingout processing) and omitted the situation of grinding process (slightly grinding processing).

With respect to this, in the illustrated existing impact style of patent documentation 1～3, normally utilizing after following manner implemented the drawing operation, and then obtain the magnetic recording media glass substrate through grinding process, polishing process etc., wherein, aforesaid way refers to: after being configured to fused glass block on counterdie, thereby utilize upper die and lower die from vertical direction, fused glass block to be applied pressing force fused glass block is carried out drawing (below, be sometimes referred to as " directly vertical punching press ").

At this, in the impact style shown in patent documentation 2, also proposed as upper die and lower die and be disposed at the material of the parallel liner between patrix and counterdie and use high rigid material etc., thereby having omitted grinding process.

In addition, in the impact style shown in patent documentation 3, propose following method, that is, in order to prevent obtaining the little plate glass of warpage when throughput rate from reducing, configured the cooling patrix of using after drawing on the drawing product.In the method, thus coolingly make the state of cooling of the upper and lower surface of drawing product become balanced with patrix by using.

In addition, in the impact style shown in patent documentation 3, also proposed except vertical directly punching press, also can implement the drawing operation by following manner, aforesaid way refers to: a pair of stamping forming die that utilizes arranged opposite in the horizontal direction applies the mode (below, be sometimes referred to as " the direct punching press of level ") of pressing force to fused glass block from horizontal direction.

[formerly technical literature]

[patent documentation]

Patent documentation 1: No. 2009-149477, Japanese communique, JP (claim 1, the 0012nd section etc.)

Patent documentation 2: No. 2003-54965, Japanese communique, JP (claim, the 0040th, 0043 section, Fig. 4～Fig. 8 etc.)

Patent documentation 3: Japanese communique, No. the 4380379th, special permission (the 0031st section, Fig. 1～Fig. 9 etc.)

Patent documentation 4: Japanese communique, No. 2003-36528, JP (Fig. 3～Fig. 6, Fig. 8 etc.)

Summary of the invention

On the other hand, aspect the throughput rate that improves the magnetic recording media glass substrate, it is very effective guaranteeing the homogeneity of the flatness of magnetic recording media glass substrate and thickness of slab and omitting or shorten to adjust the grinding process that plate thickness etc. implements as fundamental purpose.Its reason is: implementing grinding process needs grinding attachment, and, implement grinding process and can cause making increase in man-hour and increase process time that the magnetic recording media glass substrate is used.In addition, implement grinding process and also can produce the crack on glass surface, thereby studying at present the omission grinding process.

At this, from omitting or this viewpoint of shortening grinding process, after foliated glass is cut off mode and compares with impact style, as can be known, the foliated glass cut-out mode of utilizing the foliated glass of the high flatness by manufacturings such as floating method, glass tube down-drawings to process is more favourable.But, to compare with foliated glass cut-out mode, impact style also has high this advantage of utilization ratio of glass.

To utilize magnetic recording media glass substrate that vertical directly punching press makes with glass blank (below, sometimes only be called " glass blank ") thereby when implementing following process manufacturing magnetic recording media, in order to omit or to shorten grinding process, need to reduce the thickness deviation of glass blank and improve flatness.At this, by vertical directly when glass blank is made in punching press, the temperature of counterdie is set to the low-down temperature of the temperature of comparing fused glass block so that counterdie not can with the fused glass block welding of high temperature.

Therefore, be configured to from fused glass block on counterdie till begin to carry out drawing during in, the heat of fused glass block is absorbed from its face that contacts with counterdie by counterdie.Therefore, be configured in local rising of viscosity of the lower surface of the fused glass block on counterdie.Consequently, because drawing is that the fused glass block that has produced larger viscosity profile (Temperature Distribution) is carried out, thereby produce the part that is difficult to make by punching press its extension.In addition, thus the cooling velocity after drawing to be stamped into shape the different parts that extends into tabular glass compact also different.Therefore, in utilizing the vertical directly glass blank that punching press is made, thickness deviation easily increases or flatness easily reduces.

In addition, consider above-mentioned mechanism, coolingly carry out vertical directly punching press with patrix even use as shown in patent documentation 1, the thickness deviation that also is difficult to fundamentally to suppress glass blank increases and the flatness reduction.

With respect to this, in the direct punching press of the illustrated level of patent documentation 3, fused glass block is roughly being stamped into shape simultaneously as tabular that it contacts with stamping forming die.That is, compare with vertical directly punching press, in the direct punching press of level, during due to drawing, the viscosity profile of fused glass block is even, thereby it is lamellar that fused glass block is extended into equably.Therefore, can think and compare with vertical directly punching press, the thickness deviation that punching press direct according to level easily fundamentally suppresses glass blank on principle increases and the flatness reduction.

On the other hand, along with the recording density of magnetic recording media in recent years improves constantly, and require further to improve thickness deviation and the flatness of the glass that uses in the manufacturing of magnetic recording media magnetic recording media glass substrate processed or glass blank.

But people of the present invention are through discovery after scrutinizing, and the glass blank that utilizes the direct punching press of the described level of patent documentation 3 to make especially can't satisfy above-mentioned requirements (the first situation) aspect flatness.

In addition, in the one-piece type stamping forming die that uses in the direct punching press of the illustrated level of patent documentation 3, the action of gravitation direction is parallel with drawing face.Therefore, compare along the vertical directly punching press that the direction parallel with gravity direction moves be fixed in fact configuration and patrix of counterdie, in the direct punching press of level, be the drawing face easily with respect to the trend of the moving direction inclination of stamping forming die.

Therefore, in the direct punching press of level, in order to dwindle thickness deviation, need to carry out drawing under state parallel between opposed drawing face keeping.Therefore, must extremely critically control stamping forming die movement in the horizontal direction when drawing.But even improve the drive unit of stamping forming die, the measure of precision that stamping forming die moves is also limited, therefore, is difficult to improve thickness deviation, and cost also increases, thereby lacks practicality.

Therefore, even use the illustrated stamping forming die of patent documentation 3, also be difficult to further improve thickness deviation and flatness (the second situation).

First invention, second the present invention and the 3rd common issue of the present invention are to seek to improve flatness.At this, First invention and the 3rd the present invention complete in view of above-mentioned the first situation, and its problem (the first problem) is: provide a kind of magnetic recording media glass substrate that can make the outstanding glass blank of flatness with the manufacture method of glass blank and utilize the manufacture method of magnetic recording media glass substrate of this manufacture method and the manufacture method of magnetic recording media.

In addition, second the present invention completes in view of above-mentioned the second situation, its problem (the second problem) is: even provide a kind of when making glass blank by the direct punching press of level, also can make the less glass blank of thickness deviation and flatness, the magnetic recording media glass substrate with the manufacture method of glass blank, utilize this magnetic recording media glass substrate with the manufacture method of the manufacture method of the magnetic recording media glass substrate of the manufacture method of glass blank and magnetic recording media and the magnetic recording media glass substrate manufacturing installation with glass blank.

Common issue and above-mentioned the first problem are to invent to realize by following First.That is,

The first magnetic recording media glass substrate of the present invention is characterised in that with the manufacture method of glass blank: make magnetic recording media glass substrate glass blank through the first stamping procedure, the second stamping procedure and taking-up operation at least; In the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as fused glass block tabular, wherein, the first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects; In the second stamping procedure, utilize the first stamping forming die and the second stamping forming die to continue the plate glass that forms between the first stamping forming die and the second stamping forming die is carried out punching press; In taking out operation, through after this second stamping procedure, the first stamping forming die is separated with the second stamping forming die, thereby the plate glass that will be clamped between the first stamping forming die and the second stamping forming die take out; And, at least implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die; In the first stamping procedure, roughly simultaneously with after fused glass block contacts fused glass block is carried out punching press at the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die; Duration to the second stamping procedure is controlled, so that the magnetic recording media glass substrate reaches 10 μ m following (in 10 μ m) with the flatness of glass blank.

The first magnetic recording media glass substrate of the present invention one embodiment of the manufacture method of glass blank, preferably the duration of the second stamping procedure is selected, so that the temperature of the plate glass of the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ at least.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, comprise also that preferably thereby the leading section with molten glass flow cuts off the fused glass block formation operation that forms fused glass block, wherein, this molten glass flow is to make melten glass hang down and flow out continuously and form towards the lower side of vertical direction from glass flows outlet.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, the viscosity of preferred molten glass is in the scope of 500dPas～1050dPas.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferred the first stamping forming die and the second stamping forming die arranged opposite on the direction vertical with the falling direction of fused glass block.

The first magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably is about to implement the absolute value of temperature difference in the face of drawing face of the first stamping forming die before the first stamping procedure and the second stamping forming die in the scope of 0 ℃～100 ℃.

The first magnetic recording media glass substrate of the present invention preferably makes the stamping pressure in the second stamping procedure be time dependent ground reduction with another embodiment of the manufacture method of glass blank.

The first magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably reduction stamping pressure when the temperature that is clamped in the plate glass between the first stamping forming die and the second stamping forming die is reduced in the scope of the yield point of the glass material that consists of this plate glass ± 30 ℃.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferably in the process of implementing the second stamping procedure, the drawing face that makes face of plate glass and the first stamping forming die is seamless unoccupied place close contact all the time, and the drawing face that makes another face of plate glass and the second stamping forming die seamless unoccupied place close contact all the time.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferably the duration of the second stamping procedure is controlled, so that the magnetic recording media glass substrate reaches 4 μ m following (in 4 μ m) with the flatness of glass blank.

The first magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, the zone that contacts with plate glass at least of the drawing face of preferred the first stamping forming die and the second stamping forming die is the face of general planar.

The manufacture method of the first magnetic recording media glass substrate of the present invention is characterised in that: at least through the first stamping procedure, the second stamping procedure and take out operation make the magnetic recording media glass substrate with glass blank after, make the magnetic recording media glass substrate through grinding step that the magnetic recording media glass substrate is ground with the first type surface of glass blank at least; In the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as fused glass block tabular, wherein, the first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects; In the second stamping procedure, utilize the first stamping forming die and the second stamping forming die to continue the plate glass that forms between the first stamping forming die and the second stamping forming die is carried out punching press; In taking out operation, through after this second stamping procedure, the first stamping forming die is separated with the second stamping forming die, thereby the plate glass that will be clamped between the first stamping forming die and the second stamping forming die take out; And, at least implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die; In the first stamping procedure, roughly simultaneously with after fused glass block contacts fused glass block is carried out punching press at the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die; Duration to the second stamping procedure is controlled, so that the magnetic recording media glass substrate reaches 10 μ m following (in 10 μ m) with the flatness of glass blank.

One embodiment of the manufacture method of the first magnetic recording media glass substrate of the present invention, preferably the duration of the second stamping procedure is selected, so that the temperature of the above-mentioned plate glass of the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ at least.

Another embodiment of the manufacture method of the first magnetic recording media glass substrate of the present invention, preferred magnetic recording media glass substrate is identical in fact with the flatness of magnetic recording media glass substrate with the flatness of glass blank.

The manufacture method of the first magnetic recording media of the present invention is characterised in that: at least through the first stamping procedure, the second stamping procedure and take out operation make the magnetic recording media glass substrate with glass blank after, at least through the magnetic recording media glass substrate is made the magnetic recording media glass substrate with the grinding step that the first type surface of glass blank grinds, and then at least through the magnetic recording layer formation operation that forms magnetic recording layer on the magnetic recording media glass substrate and make magnetic recording media; In the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as fused glass block tabular, wherein, the first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects; In the second stamping procedure, utilize the first stamping forming die and the second stamping forming die to continue the plate glass that forms between the first stamping forming die and the second stamping forming die is carried out punching press; In taking out operation, through after this second stamping procedure, the first stamping forming die is separated with the second stamping forming die, thereby the plate glass that will be clamped between the first stamping forming die and the second stamping forming die take out; And, at least implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die; In the first stamping procedure, roughly simultaneously with after fused glass block contacts fused glass block is carried out punching press at the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die; Duration to the second stamping procedure is controlled, so that the magnetic recording media glass substrate reaches 10 μ m following (in 10 μ m) with the flatness of glass blank.

One embodiment of the manufacture method of the first magnetic recording media of the present invention, preferably the duration of the second stamping procedure is selected, so that the temperature of the above-mentioned plate glass of the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ at least.

Another embodiment of the manufacture method of the first magnetic recording media of the present invention, preferred magnetic recording media glass substrate is identical in fact with the flatness of magnetic recording media glass substrate with the flatness of glass blank.

Common issue and above-mentioned the second problem are to realize by second following the present invention.That is,

The second magnetic recording media glass substrate of the present invention is characterised in that with the manufacture method of glass blank: at least through utilizing the first stamping forming die and the second stamping forming die that the fused glass block in falling is carried out the drawing operation of drawing and makes magnetic recording media glass substrate glass blank, wherein, the first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects; At least the first stamping forming die is provided with stamping forming die main body and guiding parts at least, this stamping forming die main body is provided with drawing face, this guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and second stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of the second stamping forming die configuration contact, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained the distance of roughly fixing; The drawing operation comprises first step and second step, in first step, make the first stamping forming die and the second stamping forming die mutually near until the guiding parts of the first stamping forming die contact with the second stamping forming die, thus fused glass block is configured as plate glass, in second step, under the guiding parts of the first stamping forming die and state that the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press.

the second magnetic recording media glass substrate of the present invention one embodiment of the manufacture method of glass blank, preferred the first stamping forming die and the second stamping forming die are provided with respectively stamping forming die main body and guiding parts at least, this stamping forming die main body is provided with drawing face, this guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and another stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of another stamping forming die configuration contacts, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained roughly fixing distance, first step is implemented by following manner, and aforesaid way refers to: make the first stamping forming die and the second stamping forming die mutually close, until the guiding parts of the first stamping forming die contacts with the guiding parts of the second stamping forming die, second step is implemented by following manner, aforesaid way refers to: under the guiding parts of the first stamping forming die and state that the guiding parts of the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the stamping forming die main body of the second stamping forming die further to continue plate glass is carried out punching press.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, comprise also that preferably thereby the leading section with molten glass flow cuts off the fused glass block formation operation that forms fused glass block, wherein, this molten glass flow is to make melten glass hang down and flow out continuously and form towards the lower side of vertical direction from glass flows outlet.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, the viscosity of preferred molten glass is in the scope of 500dPas～1050dPas.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferred the first stamping forming die and the second stamping forming die arranged opposite on the direction vertical with the falling direction of fused glass block.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferably the duration of second step is controlled, so that the magnetic recording media glass substrate reaches 10 μ m following (in 10 μ m) with the flatness of glass blank.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferably the duration of second step is selected, so that the temperature of the plate glass of second step when finishing becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ at least.

The second magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably is about to implement the absolute value of difference of temperature of stamping forming die of the temperature of drawing face of the first stamping forming die before first step and the second stamping forming die in the scope of 0 ℃～10 ℃.

The second magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably is about to implement the absolute value of temperature difference in the face of drawing face of the first stamping forming die before first step and the second stamping forming die in the scope of 0 ℃～100 ℃.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, in preferably at least during enforcement drawing operation, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die, and, roughly simultaneously with after fused glass block contacts fused glass block is carried out drawing at the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die.

The second magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably continue to carry out above-mentioned second step until the temperature of plate glass to become at least the temperature of the strain point of the glass material that consists of plate glass+10 ℃ following.

The second magnetic recording media glass substrate of the present invention preferably makes the stamping pressure in second step be time dependent ground reduction with another embodiment of the manufacture method of glass blank.

The second magnetic recording media glass substrate of the present invention is with another embodiment of the manufacture method of glass blank, preferably reduction stamping pressure when the temperature that is clamped in the plate glass between the first stamping forming die and the second stamping forming die is reduced in the scope of the yield point of the glass material that consists of this plate glass ± 30 ℃.

The second magnetic recording media glass substrate of the present invention uses the flatness of glass blank at (in 10 μ m) below 10 μ m with another embodiment of the manufacture method of glass blank, preferred magnetic recording media glass substrate.

The second magnetic recording media glass substrate of the present invention uses the flatness of glass blank at (in 4 μ m) below 4 μ m with another embodiment of the manufacture method of glass blank, preferred magnetic recording media glass substrate.

The second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, the zone that contacts with plate glass at least of the drawing face of preferred the first stamping forming die and the second stamping forming die is the face of general planar.

the second magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferred the first stamping forming die and the second stamping forming die also are provided with respectively the first push mechanism and the second push mechanism, this first push mechanism along the direction vertical with drawing face towards with drawing face opposite and the configuration another stamping forming die side promote simultaneously stamping forming die main body and guiding parts, after making guiding parts by this first push mechanism and a part with opposite another stamping forming die that configures of drawing face contact, the second push mechanism along the direction vertical with drawing face towards opposite with drawing face and another stamping forming die side configuration promotes stamping forming die main body.

the manufacture method of the second magnetic recording media glass substrate of the present invention is characterised in that: make through the drawing operation at least the magnetic recording media glass substrate with glass blank after, at least make the magnetic recording media glass substrate through grinding step that the magnetic recording media glass substrate is ground with the first type surface of glass blank, wherein, in the drawing operation, utilize the first stamping forming die and the second stamping forming die to carry out drawing to the fused glass block in falling, this first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects, the at least the first stamping forming die is provided with stamping forming die main body and guiding parts at least, this stamping forming die main body is provided with drawing face, this guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and second stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of the second stamping forming die configuration contact, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained the distance of roughly fixing, the drawing operation comprises first step and second step, in first step, make the first stamping forming die and the second stamping forming die mutually near until the guiding parts of the first stamping forming die contact with the second stamping forming die, thus fused glass block is configured as plate glass, in second step, under the guiding parts of the first stamping forming die and state that the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press.

One embodiment of the manufacture method of the second magnetic recording media glass substrate of the present invention, preferred magnetic recording media glass substrate is identical in fact with the flatness of magnetic recording media glass substrate with the flatness of glass blank.

the manufacture method of the second magnetic recording media of the present invention is characterised in that: make through the drawing operation at least the magnetic recording media glass substrate with glass blank after, at least through the magnetic recording media glass substrate is made the magnetic recording media glass substrate with the grinding step that the first type surface of glass blank grinds, and then form operation and make magnetic recording media through the magnetic recording layer that forms magnetic recording layer on the magnetic recording media glass substrate at least, wherein, in the drawing operation, utilize the first stamping forming die and the second stamping forming die to carry out drawing to the fused glass block in falling, this first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects, the at least the first stamping forming die is provided with stamping forming die main body and guiding parts at least, this stamping forming die main body is provided with drawing face, this guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and second stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of the second stamping forming die configuration contact, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained the distance of roughly fixing, the drawing operation comprises first step and second step, in first step, make the first stamping forming die and the second stamping forming die mutually near until the guiding parts of the first stamping forming die contact with the second stamping forming die, thus fused glass block is configured as plate glass, in second step, under the guiding parts of the first stamping forming die and state that the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press.

One embodiment of the manufacture method of the second magnetic recording media of the present invention, preferred magnetic recording media glass substrate is identical in fact with the flatness of magnetic recording media glass substrate with the flatness of glass blank.

The second magnetic recording media glass substrate of the present invention is characterised in that with the manufacturing installation of glass blank: possess at least: melten glass flows out pipe, and it is provided with the flow export that molten glass flow is hung down towards the vertical direction lower side; A pair of shear-blade, it is configured in the both sides of the direction that hangs down of molten glass flow in opposed mode on the direction substantially vertical with the direction that hangs down of the molten glass flow that flows out the pipe outflow from melten glass, and the leading section by inserting from the both sides of molten glass flow with molten glass flow cuts off, thereby forms fused glass block; And first stamping forming die and the second stamping forming die, it is configured in the both sides of the falling direction of fused glass block in opposed mode on the direction substantially vertical with the falling direction of the fused glass block that falls towards the vertical direction lower side, thereby and be plate glass by fused glass block being clamped with the fused glass block drawing from both sides; At least the first stamping forming die possesses at least: the stamping forming die main body, and it is provided with drawing face; Guiding parts, it has following function at least, above-mentioned functions refers to: when drawing by when and second stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of the second stamping forming die configuration contact, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained the distance of roughly fixing; The first push mechanism, its along the direction vertical with drawing face towards with drawing face opposite and the configuration the second stamping forming die side promote simultaneously stamping forming die main body and guiding parts; And second push mechanism, its after making guiding parts by this first push mechanism and a part with opposite the second stamping forming die that configures of drawing face contact, along the direction vertical with drawing face towards opposite with drawing face and the second stamping forming die side configuration promotes the stamping forming die main body.

the 3rd magnetic recording media glass substrate of the present invention manufacture method of glass blank, thereby comprise that using a pair of stamping forming die to carry out direct punching press to fused glass block is configured as fused glass block the forming process of plate glass, wherein, a pair of stamping forming die opposite and the configuration and its temperature identical in fact, this magnetic recording media glass substrate is characterised in that with the manufacture method of glass blank: in forming process, utilize a pair of stamping forming die to continue the extrusion molten glass blocks, until that the temperature of fused glass block becomes the temperature of the strain point of the glass material that consists of plate glass+10 ℃ is following.

The 3rd magnetic recording media glass substrate of the present invention one embodiment of the manufacture method of glass blank, preferably at the state of keeping fused glass block and a pair of stamping forming die close contact until after the temperature of fused glass block becomes below the strain point of glass material, carry out annealing in process.

The 3rd magnetic recording media glass substrate of the present invention another embodiment of the manufacture method of glass blank, preferred forming process comprises for the first stamping procedure of the thickness of slab of determining plate glass and is used for improving the second stamping procedure of the flatness of plate glass, and uses a pair of stamping forming die to carry out continuously the first stamping procedure and the second stamping procedure.

The 3rd magnetic recording media glass substrate of the present invention is preferably implemented forming process according to the mode that thickness reaches below 2mm and flatness reaches below 10 μ m of plate glass with another embodiment of the manufacture method of glass blank.

The manufacture method of the 3rd magnetic recording media glass substrate of the present invention is characterised in that: make magnetic recording media glass substrate glass blank by the 3rd magnetic recording media glass substrate of the present invention with the manufacture method of glass blank, thereby and the magnetic recording media glass substrate is processed with glass blank made the magnetic recording media glass substrate.

The manufacture method of the 3rd magnetic recording media of the present invention is characterised in that: make the magnetic recording media glass substrate by the manufacture method of the 3rd magnetic recording media glass substrate of the present invention, and form operation and make magnetic recording media through the magnetic recording layer that forms magnetic recording layer on the magnetic recording media glass substrate at least.

(invention effect)

According to First invention and the 3rd the present invention, can provide the magnetic recording media glass substrate that to make the outstanding glass blank of flatness with the manufacture method of glass blank and utilize the manufacture method of magnetic recording media glass substrate of the method and the manufacture method of magnetic recording media.

According to second the present invention, even can provide when making glass blank by the direct punching press of level, also can make the less glass blank of thickness deviation and flatness, the magnetic recording media glass substrate with the manufacture method of glass blank, utilize this magnetic recording media glass substrate with the manufacture method of the manufacture method of the magnetic recording media glass substrate of the manufacture method of glass blank and magnetic recording media and the magnetic recording media glass substrate manufacturing installation with glass blank.

Description of drawings

Fig. 1 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, the part of whole operation is described.

Fig. 2 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 3 means the mode sectional drawing of an example of the fused glass block in the whereabouts.

Fig. 4 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 5 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 6 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 7 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 8 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Fig. 9 is the mode sectional drawing that in the example of manufacture method of glass blank of First embodiment, other parts of whole operation is described.

Figure 10 means the mode sectional drawing of an example of the stamping forming die that uses in the manufacture method of glass blank of First embodiment.

Figure 11 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, the part of whole operation is described.

Figure 12 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 13 means the mode sectional drawing of an example of the fused glass block in the whereabouts.

Figure 14 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 15 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 16 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 17 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 18 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 19 is the mode sectional drawing that in the example of manufacture method of glass blank of the second present embodiment, other parts of whole operation is described.

Figure 20 means the mode sectional drawing of an example of the concrete structure more of the stamping forming die that uses in the manufacture method of glass blank of the second present embodiment.

Figure 21 means another routine mode sectional drawing of the stamping forming die that uses in the manufacture method of glass blank of the second present embodiment.

Figure 22 is the mode sectional drawing of the stamping forming die that uses in Comparative examples A 1.

Figure 23 is the mode sectional drawing of the stamping forming die that uses in Comparative examples A 2.

(symbol description)

10 melten glass flow out pipe 12 glass flows outlets

20 molten glass flow 22 leading sections

24 fused glass block 26 plate glass

30 lower blade (shear-blade), 32 main parts

34 blade part 34U (blade part) upper surfaces

34B (blade part) lower surface 40 upper blade (shear-blade)

42 main part 44 blade parts

44U (blade part) upper surface 44B (blade part) lower surface

50 first stamping forming die 50S stamping forming dies

52 stamping forming die main body 52A drawing faces

52B is pushed face 54 guiding parts

54A spigot surface 54B is pushed face

56 first push mechanism 56A promote face

56B promotes the face 56H through hole of the opposition side of face 56A

58 second push mechanism 60 second stamping forming dies

62 stamping forming die main body 62A drawing faces

64 guiding parts 64A spigot surfaces

110 melten glass flow out pipe 112 glass flows outlets

120 molten glass flow 122 leading sections

124 fused glass block 126 plate glass

130 lower blade (shear-blade), 132 main parts

134 blade part 134U (blade part) upper surfaces

134B (blade part) lower surface 140 upper blade (shear-blade)

142 main part 144 blade parts

144U (blade part) upper surface 144B (blade part) lower surface

150 first stamping forming die 150S stamping forming dies

152 stamping forming die main body 152A drawing faces

152B is pushed face 154 guiding parts

154A spigot surface 154B is pushed face

156 first push mechanism 156A promote face

156B promotes the face 156H through hole of the opposition side of face 156A

158 second push mechanism 160 second stamping forming dies

162 stamping forming die main body 162A drawing faces

164 guiding parts 164A spigot surfaces

170 support unit 200 stamping forming dies

Embodiment

＜First embodiment 〉

(the magnetic recording media glass substrate manufacture method of glass blank)

the manufacture method of the magnetic recording media glass substrate use glass blank of First embodiment (below, sometimes referred to as " manufacture method of glass blank ") be characterised in that: at least through the first stamping procedure, the second stamping procedure and taking-up operation are made magnetic recording media glass substrate glass blank, wherein, in the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as fused glass block tabular, this first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects, in the second stamping procedure, utilize the first stamping forming die and the second stamping forming die to continue the plate glass that forms between the first stamping forming die and the second stamping forming die is carried out punching press, in taking out operation, through after this second stamping procedure, the first stamping forming die is separated with the second stamping forming die, thereby the plate glass that will be clamped between the first stamping forming die and the second stamping forming die take out, and, at least implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die, in the first stamping procedure, after the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die roughly contacts with fused glass block simultaneously, fused glass block is carried out punching press, duration to above-mentioned the second stamping procedure is controlled, so that the flatness of above-mentioned glass blank reaches 10 μ m following (in 10 μ m).

At this, in present specification, so-called " magnetic recording media glass substrate " refers to the glass substrate used by the magnetic recording media that amorphous glass (amorphous glass) is made.

In the first stamping procedure of the manufacture method of the glass blank of First embodiment, with existing impact style be similarly to temperature far above the strain point (strain point) of glass material thus thereby hold fused glass block under yielding state and carry out punching press and it is configured as tabular.At this moment, after the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die roughly contacts with fused glass block simultaneously, fused glass block is carried out punching press.

In addition, implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die.Therefore, the two sides that is shaped as the fused glass block in tabular process and is clamped in the plate glass under state between a pair of stamping forming die in the first stamping procedure in the second stamping procedure be all the time continued symmetrically cooling.

Therefore, with for comparing because produced the vertical direct punching press that fused glass block under the state of viscosity profile carries out drawing with the counterdie Long contact time, in the manufacture method of the glass blank of First embodiment, can produce temperature difference hardly on plate glass two sides after drawing, thereby can suppress reliably to cause because of the temperature difference on two sides flatness to reduce.

On the other hand, thus the high mobility of temperature large (viscosity is low) of plate glass after the first stamping procedure has just finished soon.Therefore, plate glass is in very easily distortion and the state of the easy variation of flatness.But, in the second stamping procedure of and then implementing after the first stamping procedure, utilize the first stamping forming die and the second stamping forming die to continue the plate glass that forms between the first stamping forming die and the second stamping forming die is carried out punching press.And control the duration of the second stamping procedure this moment, so that the flatness of glass blank reaches 10 μ m following (in 10 μ m).In addition, the mode that preferably reaches (in 4 μ m) below 4 μ m according to the flatness of glass blank is controlled the duration of the second stamping procedure.Thus, can make the flatness of the glass blank that makes become better.

In addition, when duration of the second stamping procedure more in short-term, can cause because of disturbance (disturbance) the plate glass generation warpage in cooling procedure, this warpage can cause the flatness variation of glass blank.Therefore, change the duration of the second stamping procedure, and the flatness of resulting glass blank is measured, the mode that reaches (in 10 μ m) below 10 μ m according to the flatness of measuring is set the duration of the second stamping procedure, thereby makes glass blank.

But throughput rate reduces when the duration of the second stamping procedure is long, therefore, preferably sets the duration of the second stamping procedure after the flatness of considering glass blank and throughput rate.From the point of view, the duration of the second stamping procedure is preferred in the scope of 2 seconds～40 seconds, more preferably in the scope of 2 seconds～30 seconds specifically.

In addition, in the second stamping procedure, for the flatness with glass blank controls to (in 10 μ m) below 10 μ m, especially preferably select in the following manner the duration of the second stamping procedure, wherein, aforesaid way refers to: lose the temperature range that in fact can not deform thereby continue that plate glass is carried out punching press until the temperature of plate glass is reduced to the mobility of plate glass.In this situation, can be after keeping the first stamping procedure and just having finished make the plate glass sclerosis in soon the repressed state of distortion of plate glass.Thus, can make the flatness of the glass blank that makes become better.

At this, about the duration of the second stamping procedure, the mode that the temperature of the plate glass when preferably finishing according to the second stamping procedure becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ is selected, the mode that more preferably becomes below the temperature of strain point+5 ℃ according to the temperature of above-mentioned plate glass is selected, and the mode that further preferably becomes below strain point according to the temperature of above-mentioned plate glass is selected.

On the other hand, the lower limit temperature of the temperature of the plate glass when the second stamping procedure finishes is not particularly limited, but the viewpoint that causes throughput rate to reduce because implement the required time of the second stamping procedure to increase from suppressing is more than being preferably strain point from point of view of practicability.Therefore, the higher limit of the duration of the second stamping procedure is also preferably selected from this viewpoint.

In the manufacture method of the glass blank of First embodiment, must be at least implement the first stamping procedure and the second stamping procedure during in, make the temperature of drawing face of the first stamping forming die identical in fact with the temperature of the drawing face of the second stamping forming die.At this, so-called " identical in fact " refers to: the absolute value of the temperature difference of the temperature of the temperature of the drawing face of the first stamping forming die and the drawing face of the second stamping forming die is in 10 ℃.The absolute value of this temperature difference more preferably in 5 ℃, most preferably is 0 ℃.

At this, when having Temperature Distribution in drawing face, so-called " temperature of drawing face " refers near the temperature of the position central part of drawing face.In addition, as a reference, in vertical directly impact style, although also the condition according to drawing is different and different for the absolute value of the drawing face that fused glass block is carried out the patrix in stamping process and the temperature difference of the drawing face of counterdie, generally 50 ℃～100 ℃ left and right.

In addition, in the first stamping procedure, after the drawing face of the drawing face that makes the first stamping forming die and the second stamping forming die roughly contacts with fused glass block simultaneously, fused glass block is carried out punching press.At this, so-called " roughly simultaneously contact " refers to: the absolute value of the mistiming between the time point that fused glass block contacts with a drawing face and fused glass block and time point that another drawing face contacts is in 0.1 second.The absolute value of this mistiming more preferably in 0.05 second, most preferably is 0 second.

In addition, as a reference, in vertical directly impact style, although from after the drawing face contact of fused glass block and counterdie to fused glass block so that with time required till the drawing face of patrix contacts also different and different according to the condition of drawing, be generally 1.5 seconds～about 3 seconds.

In addition, even according to existing vertical directly impact style, as long as utilizing after upper die and lower die are configured as plate glass with fused glass block, in order to the state that continues with upper die and lower die plate glass is carried out punching press, plate glass is cooled to temperature near strain point, also can expects significantly to improve the flatness of glass blank.But, in this situation, because the drawing required time of a glass blank significantly increases, therefore, thereby can't avoid the significantly reduction of throughput rate to lack practicality (with reference to the 0009th section of patent documentation 1).

Therefore, the present patent application people abandons adopting or practically in order to the state that continues with upper die and lower die plate glass is carried out punching press, plate glass is cooled to technology near the temperature of strain point in vertical directly punching press, but by utilizing cooling various substitute technologies with patrix etc. to seek to improve the flatness of throughput rate and glass blank as illustrated in patent documentation 1.

According to above-mentioned situation, even can think in the situation that produce glass blank in batches by the direct punching press of level, thereby it is also extremely important the first stamping forming die being separated with the second stamping forming die glass blank is taken out, wherein, the direct punching press of level refers to utilizing a pair of stamping forming die to carry out impact style identical with vertical directly punching press on the drawing this point.This be because: by like this, after fused glass block is configured as plate glass, easily realize simultaneously the improvement of the flatness of throughput rate and glass blank.

Therefore, can think in the situation that produce glass blank in batches by the direct punching press of level, thereby implementing throughput rate that the second stamping procedure only can make glass blank significantly reduces and lacks practicality, wherein, this second stamping procedure refers to: also continue plate glass is carried out punching press after fused glass block becomes plate glass, until the temperature of this plate glass becomes the following temperature of temperature of strain point+10 ℃.But, after scrutinizing, the processes such as the inventor find, do not cause throughput rate significantly to reduce the degree that diminishes practicality even implemented the second stamping procedure in the direct punching press of level yet.It is the reasons are as follows.

At first, in vertical directly punching press, carry out drawing after being configured to fused glass block on counterdie.The fused glass block that therefore, must utilize upper die and lower die pair to produce larger Temperature Distribution (viscosity profile) with the counterdie Long contact time carries out drawing.With respect to this, in the direct punching press of level, in the mode of utilizing the fused glass block of a pair of stamping forming die in falling to clamp, fused glass block is carried out drawing.That is, in the time before beginning to carry out drawing, fused glass block can not form the film continuous contact with a punching press, thereby the Temperature Distribution of the fused glass block when beginning to carry out drawing (viscosity profile) is extremely even.

Therefore, want to make in the situation of the identical glass blank of thickness with vertical directly punching press by the direct punching press of level, with respect to the direct punching press of level, must consider the Temperature Distribution of fused glass block and the medial temperature of fused glass block is set as higher temperature in vertical directly punching press, lamellar by drawing, fused glass block is extended into more equably.Therefore, compare with the direct punching press of level, in vertical directly punching press, the medial temperature of the fused glass block when beginning to carry out drawing and the temperature difference of strain point are larger.This situation (the first situation) means: in the situation that the cooling velocity of the fused glass block in the direct punching press of level and vertical directly these two kinds of impact styles of punching press and plate glass is identical, when fused glass block being configured as the temperature that further it is cooled to after tabular near strain point, to compare the required time of the direct punching press of level shorter with vertical directly punching press.

And in the situation that the thermal capacity of the stamping forming die in two kinds of impact styles of hypothesis is identical, the cooling velocity of fused glass block and plate glass depends on the temperature of a pair of stamping forming die that contacts with fused glass block.That is, in the situation that the stamping forming die cooling velocity that serviceability temperature is low when beginning to carry out drawing increases, in the high stamping forming die situation of serviceability temperature, cooling velocity reduces.At this, in vertical directly punching press, due to counterdie and fused glass block Long contact time in the time before beginning to carry out drawing, therefore, in the time before beginning to carry out drawing, counterdie is melted the glass blocks heating.Therefore, in vertical directly punching press, be that a stamping forming die (counterdie) in a pair of stamping forming die is under the state of high temperature and begins to carry out drawing.This situation (the second situation) means: compare with vertical directly punching press, be very easy to make the cooling velocity of fused glass block and plate glass to become larger in the direct punching press of level.

Therefore, consider that above-mentioned two situations are as can be known clear and definite, compare with vertical directly punching press, punching press direct according to level can significantly be shortened fused glass block is configured as tabular further it is cooled near the required time of the temperature of strain point afterwards.Therefore, even implement the second stamping procedure in the direct punching press of level, can not make throughput rate significantly reduce the situation that diminishes practicality as vertical directly punching press yet.

The manufacture method of the glass blank of First embodiment discussed above as long as comprise that at least the first stamping procedure, the second stamping procedure and taking-up operation just are not particularly limited, still, comprises also preferably that usually fused glass block forms operation.Below, in further detail each operation that comprises fused glass block formation operation is described.In addition, omitted in the following description explanation about the above aspect.

-fused glass block formation operation-

Form in operation at fused glass block, make the fused glass block as the drawing object.The manufacture method of fused glass block is not particularly limited, normally thereby the leading section with molten glass flow cuts off the formation fused glass block, wherein, this molten glass flow makes melten glass hang down and flow out continuously and form towards the vertical direction lower side from the glass flows outlet.In addition, when implementing the cut-out that from molten glass flow, its leading section is separated, can use a pair of shear-blade.In addition, about the viscosity of melten glass, so long as be suitable for the cut-out of leading section or the viscosity of drawing just is not particularly limited, still, usually preferably be controlled to be the fixed value in 500dPas～1050dPas scope.

Next, the concrete example that in further detail fused glass block is formed operation with reference to the accompanying drawings describes.

Form in operation at fused glass block, as shown in Figure 1, molten glass flow 20 flows out the bottom of pipe 10 from being arranged at melten glass glass flows outlet 12 lower side towards vertical direction are flowed out continuously, wherein, the melten glass upper end of flowing out pipe 10 is connected with not shown melten glass supply source.

On the other hand, the lower side of glass flows outlet 12 and molten glass flow 20, with the substantially vertical direction of central shaft D of the direction that hangs down of molten glass flow 20 on both sides, dispose respectively the first shear-blade (lower blade) 30 and the second shear-blade (upper blade) 40.And, lower blade 30 and upper blade 40 move towards arrow X1 direction and arrow X2 direction respectively, thus from the both sides of molten glass flow 20 near leading section 22 sides of molten glass flow 20, wherein, arrow X1 direction is vertical with central shaft D and be to advance towards the right side from the left side in the drawings, and arrow X2 direction is vertical with central shaft D and be to advance towards the left side from the right side in the drawings.In addition, the temperature that flows out the melten glass supply source of pipe 10 or its upstream by regulating melten glass is controlled the viscosity of molten glass flow 20.

In addition, lower blade 30 and upper blade 40 have roughly tabular main part 32,42 and blade part 34,44, wherein, this blade part 34,44 is arranged at main part 32,42 end side, and the leading section 22 of the molten glass flow 20 that will flow out continuously towards the vertical direction lower side from the direction substantially vertical with the direction that hangs down of molten glass flow 20 cuts off.

In addition, the upper surface 34U of blade part 34 and the lower surface 44B of blade part 44 form and surface level consistent face roughly, and the lower surface 34B of blade part 34 and the upper surface 44U of blade part 44 form the face that tilts in the mode that intersects with surface level.In addition, lower blade 30 and upper blade 40 are configured to: the upper surface 34U of blade part 34 and the lower surface 44B of blade part 44 are on the height and position of roughly the same degree with respect to vertical direction.

Then, as shown in Figure 2, according to lower blade 30 and upper blade 40 are further moved towards arrow X1 direction and arrow X2 direction respectively, thereby the lower surface 44B part of the upper surface 34U that makes blade part 34 and blade part 44 is the mode that overlaps of seamless unoccupied place almost, make lower blade 30 and upper blade 40 respectively along continuous straight runs move.That is, lower blade 30 and upper blade 40 are vertically intersected with respect to central shaft D.

Thus, lower blade 30 and upper blade 40 are inserted near the position of central shaft D of molten glass flow 20, thereby leading section 22 is cut into roughly spherical fused glass block 24.In addition, Fig. 2 represents that leading section 22 is with the form of fused glass block 24 state from main part separated moment of molten glass flow 20.And as shown in Figure 3, the fused glass block 24 that cuts off out from molten glass flow 20 further falls towards the below of vertical direction Y1 side.

The-the first stamping procedure-

In the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block 24 in whereabouts shown in Figure 3 is configured as it tabular, wherein, the first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with fused glass block 24 intersects.At this, the first stamping forming die and the second stamping forming die be arranged opposite, especially preferably arranged opposite on the direction vertical with the falling direction of fused glass block 24 on the direction substantially vertical with the falling direction of the mode of angle in the falling direction of fused glass block 24 forms 90 degree ± 1 degree scopes and fused glass block 24 preferably.Thus, by a pair of stamping forming die of falling direction arranged opposite with respect to fused glass block 24, being more prone to from both sides is tabular with fused glass block 24 drawings equably.

In addition, be about to implement the temperature of drawing face before the first stamping procedure, the first stamping forming die and the second stamping forming die, preferably below the temperature of the strain point of the glass material that consists of fused glass block 24+10 ℃, more preferably below the temperature of the strain point of the glass material that consists of fused glass block 24+5 ℃.By with the temperature setting of drawing face in above-mentioned scope, can suppress reliably fused glass block 24 and drawing face generation welding when carrying out drawing.

The lower limit that is about to implement drawing surface temperature before the first stamping procedure, the first stamping forming die and the second stamping forming die is not particularly limited, but, the extensibility that causes glass blank to break from preventing because of the quenching of fused glass block 24 and prevent from causing because the viscosity during drawing sharply increases fused glass block 24 is the viewpoint of the practical aspect such as reductions significantly, preferably more than the strain point of the glass material of formation fused glass block 24.

In addition, be about to implement the absolute value of difference of temperature of drawing face of the temperature of drawing face before the first stamping procedure, the first stamping forming die and the second stamping forming die preferably in the scope of 0 ℃～10 ℃, more preferably in the scope of 0 ℃～5 ℃, especially be preferably 0 ℃.In this situation, can be suppressed at more reliably on the two sides that is formed tabular plate glass by fused glass block 24 being carried out punching press and produce temperature difference, thereby can further improve flatness.

In addition, be about to implement the absolute value of temperature difference in the face of drawing face before the first stamping procedure, the first stamping forming die and the second stamping forming die, preferably in the scope of 0 ℃～100 ℃, more preferably in the scope of 0 ℃～50 ℃, especially be preferably 0 ℃.By the Temperature Distribution in drawing face is located in above-mentioned scope, be more prone to make fused glass block 24 to extend into equably when carrying out drawing lamellar.Consequently, even in the situation that the thinner glass blank of manufacturing thickness of slab also is more prone to obtain flatness well and the also little glass blank of thickness deviation.

Need to prove, so-called " face of drawing face in temperature " refers to: when drawing drawing face with extend into the maximum region that tabular fused glass block 24 contacts in the temperature measured.

Then, more specifically the first stamping procedure is described with reference to the accompanying drawings.

At first, as shown in Figure 4, fused glass block 24 shown in Figure 3 enters between first stamping forming die 50 and the second stamping forming die 60 of arranged opposite on the direction vertical with the falling direction Y1 of fused glass block 24.At this, implement drawing the first stamping forming die 50 before and be configured to the second stamping forming die 60: line is symmetrical and mode that be separated from each other on the direction vertical with falling direction Y1 is opposed to be with respect to falling direction Y1.

Then, thereby carry out drawing from both sides extrusion molten glass blocks 24 opportunity of position in order to arrive near the vertical direction central portion of the first stamping forming dies 50 and the second stamping forming die 60 with fused glass block 24 with matching, and the first stamping forming die 50 is moved towards arrow X1 direction vertical with falling direction Y1 and that advance towards the right side from the left side in the drawings, the second stamping forming die 60 is moved towards arrow X2 direction vertical with falling direction Y1 and that advance towards the left side from the right side in the drawings.

In addition, the translational speed that moves towards arrow X2 direction of the translational speed that moves towards arrow X1 direction of the first stamping forming die 50 and the second stamping forming die 60 is set to identical or roughly the same.

At this, stamping forming die 50,60 has and is roughly discoid stamping forming die main body 52,62 and guiding parts 54,64, and wherein, guiding parts 54,64 is configured to this stamping forming die main body 52,62 outer circumference end are surrounded.In addition, because Fig. 4 is sectional view, therefore, is depicted as guiding parts 54,64 and is positioned at stamping forming die main body 52,62 both sides up and down in Fig. 4.In addition, omitted in figure and make stamping forming die 50 move, make the record of the driver part that stamping forming die 60 moves towards arrow X2 direction towards arrow X1 direction.

Stamping forming die main body 52, a face of 62 become drawing face 52A, 62A.And in Fig. 4, the first stamping forming die 50 and the second stamping forming die 60 are that separately drawing face 52A, 62A is opposite by arranged opposite.In addition, guiding parts 54 is being provided with spigot surface 54A with respect to drawing face 52A on the height and position that the X1 direction is given prominence to a little, and guiding parts 64 is being provided with spigot surface 64A with respect to drawing face 62A on the height and position that the X2 direction is given prominence to a little.Therefore, when carrying out drawing, spigot surface 54A and spigot surface 64A connect, thereby are formed with the gap between drawing face 52A and drawing face 62A.Therefore, the width in this gap is the thickness that is stamped into shape as tabular fused glass block 24, is the thickness of glass blank between the first stamping forming die 50 and the second stamping forming die 60.

In addition, drawing face 52A, 62A are formed: thus by implement the first stamping procedure make fused glass block 24 between the drawing face 62A of the drawing face 52A of the first stamping forming die 50 and the second stamping forming die 60 vertically when extruding launches to be shaped as plate glass fully, the zone that contacts with above-mentioned plate glass at least (melten glass elongated area) S1, the S2 of drawing face 52A, 62A are the face of general planar.

In addition, in example shown in Figure 4, comprise the drawing face 52A of melten glass elongated area S1 and comprise whole of drawing face 62A of melten glass elongated area S2, form usually said curvature in fact and be 0 tabular surface.In addition, only exist small concavo-convexly and do not exist than this small concavo-convex larger protuberance and/or recess on this tabular surface, wherein, this is small, and concavo-convex to refer to implement common smoothing processing or mirror ultrafinish processing etc. when making stamping forming die formed concavo-convex.

Glass blank utilizes drawing face 52A, 62A extrusion molten glass blocks 24 to carry out drawing and make.Therefore, the surfaceness of the surfaceness of drawing face 52A, 62A and glass blank first type surface is almost identical.From carrying out the line processing of implementing as rear operation described later and with the grinding aspect of diamond chip, the surfaceness of glass blank first type surface (center line average roughness Ra) is preferably in the scope of 0.01 μ m～10 μ m, therefore, the surfaceness of drawing face (center line average roughness Ra) is also preferred in the scope of 0.01 μ m～10 μ m.

Fused glass block 24 shown in Figure 4 further falls towards the below, and enters between two drawing face 52A, 62A.Then, as shown in Figure 5, during the position, the while contacts with drawing face 52A, 62A the both side surface of fused glass block 24 simultaneously or roughly near fused glass block 24 arrives substantial middle section on the above-below direction of drawing face 52A, the 62A parallel with falling direction Y1.

At this, become because the viscosity of the fused glass block 24 in falling increases when also considering when being difficult to drawing or causing stamping position to produce the viewpoint of change because falling speed becomes too fast, distance of fall is preferably selected in the scope below 1000mm, more preferably select in the scope below 500mm, further preferably select in the scope below 300mm, most preferably select in the scope below 200mm.In addition, the lower limit of distance of fall is not particularly limited, still, from point of view of practicability preferably more than 100mm.

Need to prove, should " distance of fall " refer to: from leading section 22 as Fig. 2 as illustrated in the form of fused glass block 24 separated moment, position that to be lower blade 30 overlap in vertical direction with upper blade 40 extremely as the example shown in figure 5 begin to carry out drawing the time (beginning to carry out the moment of drawing) the substantial middle section that makes progress of the footpath of position, drawing face 52A, the 62A parallel with falling direction Y1 near distance till the position.

Then, as shown in Figure 6, when utilizing the first stamping forming die 50 and the second stamping forming die 60 to continue extrusion molten glass blocks 24 from both sides, fused glass block 24 is extruded expansion with uniform thickness centered by fused glass block 24 and position that drawing face 52A, 62A begin to contact most.Then, utilize the first stamping forming die 50 and the second stamping forming die 60 to continue to push, until spigot surface 54A contacts with spigot surface 56A as shown in Figure 7, form thus discoid between drawing face 52A, 62A or discoid plate glass 26 roughly.

At this, plate glass 26 shown in Figure 7 has shape and the thickness identical in fact with the glass blank that finally obtains.And the size and dimension on plate glass 26 two sides is consistent with the size and dimension of melten glass elongated area S1, S2 (not shown in Fig. 7).In addition, from making the viewpoint of fused glass block 24 thin plates, state when beginning from drawing shown in Figure 5 becomes the required time of state that spigot surface 54A shown in Figure 7 contacts with spigot surface 64A (below, be sometimes referred to as " drawing time ") preferably in 0.1 second.

In addition, when carrying out drawing, be the state that spigot surface 54A contacts with spigot surface 64A, easily keep thus the parastate between drawing face 52A and drawing face 62A.In addition, the lower limit of drawing time is not particularly limited, still, from point of view of practicability preferably more than 0.05 second.

In addition, Fig. 4～stamping forming die 50 shown in Figure 7 has stamping forming die main body 52 and guiding parts 54, and stamping forming die 60 also has identical structure.But a pair of stamping forming die that uses in the manufacture method for the glass blank of First embodiment is so long as can be the stamping forming die that tabular stamping forming die just is not limited to Fig. 4～type shown in Figure 7 with fused glass block 24 drawings.For example, also can use the stamping forming die of following type as a pair of stamping forming die, that is the type (without leading-portion type) that, is consisted of by the stamping forming die main body 52,62 after from the stamping forming die 50,60 of Fig. 4～shown in Figure 7, guiding parts 54,64 being omitted.

In addition, Fig. 4～ stamping forming die 50,60 shown in Figure 7 can be stamping forming die main body 52,62 and guiding parts 54,64 be integratedly consist of one-piece type, can be also stamping forming die main body 52,62 and guiding parts 54, opened the divergence type of formation in 64 minutes.In addition, in the situation that stamping forming die 50,60 is the divergence type stamping forming die, in the first stamping procedure, stamping forming die main body 52 is integratedly with guiding parts 54 and moves towards arrow X1 direction simultaneously, and stamping forming die main body 62 is integratedly with guiding parts 64 and moves towards arrow X2 direction simultaneously.

In addition, because stamping forming die 50,60 has respectively guiding parts 54,64, therefore, and under guiding parts 54 as shown in Figure 7 and state that guiding parts 64 contacts, drawing face 52A and drawing face 62A keeping parallelism.Therefore, even moving, make stamping forming die 60 drawing face 52A and drawing face 62A in the process that arrow X2 direction moves to keep parastate as Fig. 4～make as shown in Figure 6 stamping forming die 50 towards arrow X1 direction, also easily make the thickness deviation of resulting glass blank become very little.Therefore, and do not require drive stamping forming die 50,60 drive unit has the control ability of carrying out following control, that is, make drawing face 52A and drawing face 62A keep all the time parastate accurately in Fig. 4～series of processes shown in Figure 7.

The-the second stamping procedure-

In the second stamping procedure, utilize the first stamping forming die 50 and the second stamping forming die 60 to continue the plate glass 26 that forms between the first stamping forming die 50 and the second stamping forming die 60 is carried out punching press.That is, in soon state, utilize the first stamping forming die 50 and the second stamping forming die 60 to continue plate glass 26 is carried out punching press after keeping the first stamping procedure shown in Figure 7 and just having finished.And control the duration of the second stamping procedure this moment, so that the flatness of glass blank reaches 10 μ m following (in 10 μ m).

In addition, in during till when soon to the second stamping procedure finishes after the first stamping procedure that contacts with fused glass block 24 from drawing face 52A, 62A has just begun, glass (fused glass block 24 and plate glass 26) between drawing face 52A and drawing face 62A although the glass material that uses in also according to drawing of temperature different and different, be generally significantly to be reduced to 480 ℃ ± 20 ℃ left and right from 1200 ℃ ± 50 ℃ left and right.In addition, owing to continuing also that in the second stamping procedure plate glass 26 is carried out punching press, therefore, the mobility of plate glass 26 also reduces along with the process of time.Especially in the situation that continue plate glass 26 is carried out punching press until the temperature of plate glass 26 is reduced to below the temperature of the strain point of the glass material that consists of plate glass 26+10 ℃, the mobility of plate glass 26 is almost completely lost.

Therefore, in the second stamping procedure, be accompanied by that temperature reduces so significantly and thermal shrinkage occurs plate glass 26 diametrically.On the other hand, think in the second stamping procedure, thereby thereby the heat that the drawing face 52A, the 62A that contact with the two sides of plate glass 26 continue to absorb plate glass 26 stops on in-plane thermal expansion or transfers thermal shrinkage slowly in thermal expansion on in-plane or from no longer absorbing heat after plate glass 26 has absorbed enough heats.

That is, in the second stamping procedure, between the two sides and drawing face 52A, 62A of plate glass 26, the thermal expansion between two parts or the degree of thermal shrinkage are different.Therefore, in the second stamping procedure, by drawing face 52A, 62A, the two sides of the plate glass 26 under the thermal shrinkage state is applied the power wanting plate glass 26 is radially expanded, namely is reverse power with the thermal shrinkage direction.But, in the second stamping procedure, because the mobility of the plate glass 26 along with the carrying out of the second stamping procedure significantly reduces, therefore, plate glass 26 is applied too much stress easily causes plate glass 26 that brittle fractures occur.Therefore, apply when being reverse power with the thermal shrinkage direction when continue two sides to plate glass 26 always, can produce too much stress on the in-plane of plate glass 26, thereby can cause plate glass 26 to break.

In order to prevent breaking of plate glass 26 as described above, consider that (1) use thermal expansivity to approach the material of the thermal expansivity of the glass material that consists of plate glass 26 as consisting of stamping forming die 50,60 material, and, (2) in the second stamping procedure, the temperature of plate glass 26 and the temperature of drawing face 52A, 62A are synchronously reduced.But, owing to being attended by significantly temperature variation in the second stamping procedure, therefore, want to implement as described above cooling, cooling velocity must be very little.But in this situation, the enforcement required time of the second stamping procedure significantly increases, and therefore, lacks practicality thereby might cause mass productivity significantly to reduce.

Consider aspect discussed above, preferably be time dependent ground reduction stamping pressure in the second stamping procedure, break in the second stamping procedure to prevent more reliably plate glass 26.In this situation, by reducing stamping pressure, the friction factor between the two sides of plate glass 26 and drawing face 52A, 62A reduces.So, produce between the two sides of plate glass 26 and drawing face 52A, 62A and slide, thus easily interrupt two sides to plate glass 26 apply become the reason of breaking be reverse power with the thermal shrinkage direction.

At this, so-called " time dependent ground reduction stamping pressure " not only is included in the situation that reduces stamping pressure in the second stamping procedure along with the process of time, also comprise following situation, namely, even the situation that stamping pressure temporarily increases or keep fixed value occurs along with the process of time, but its gradient is negative value when stamping pressure is similar to linear function with respect to the variation of time.In addition, stamping pressure can be reduced along with the process of time interimly, also stamping pressure can be reduced continuously along with the process of time.

In addition, in the situation that reduce stamping pressure along with the process of time interimly, preferred reduction stamping pressure when the temperature that is clamped in the plate glass 26 between the first stamping forming die 50 and the second stamping forming die 60 is reduced in the scope of the yield point of the glass material that consists of plate glass 26 ± 30 ℃.Thus, can more effectively suppress breaking of plate glass 26 by the operation of fairly simple stamping pressure.In addition, in this situation, from making the state that breaks and suppress the flatness variation that suppresses reliably plate glass 26 keep the viewpoint that realizes simultaneously evenly, in the time reducing front stamping pressure and be made as 100%, the stamping pressure after reduction is preferably in the scope of 1%～10% left and right.

In addition, in the second stamping procedure, stamping pressure time dependent ground is reduced and make stamping pressure time dependent ground be wave change.In this situation, such as can make along with the process of time stamping pressure be as wavy in rectangle or sinusoidal wave shape etc. be periodically and change.In this situation, when stamping pressure was near minimal value along with the process of time, the friction factor between the two sides of plate glass 26 and drawing face 52A, 62A reduced.So, produce between the two sides of plate glass 26 and drawing face 52A, 62A and slide, thus easily interrupt two sides to plate glass 26 apply become the reason of breaking be reverse power with the thermal shrinkage direction.

In addition, in the second stamping procedure, not only thermal shrinkage diametrically and also can produce trickle thermal shrinkage on thickness direction of plate glass 26.Therefore, in the process of implementing the second stamping procedure, produce sometimes small gap between drawing face 52A or drawing face 62A and plate glass 26.In this situation, compare during with plate glass 26 seamless unoccupied place close contact with drawing face 52A and drawing face 62A, when producing the gap, the heat conduction efficiency between two parts reduces.Therefore, easily produce Temperature Distribution in the two sides of plate glass 26 or face.Such Temperature Distribution can cause the interior generation viscosity profile of plate glass 26 (mobility is irregular), therefore, easily makes on plate glass 26 and produces warpage, thereby easily make the flatness variation of resulting glass blank.

When considering aspect discussed above, preferably in the process of implementing the second stamping procedure, face of plate glass 26 and the drawing face 52A of the first stamping forming die 50 be seamless unoccupied place close contact all the time, and the drawing face 62A of another face of plate glass 26 and the second stamping forming die 60 is seamless unoccupied place close contact all the time.In this situation, can use its drawing face with respect to the outstanding stamping forming die of servo-actuated property of the thermal shrinkage on the thickness direction of plate glass 26 as a pair of stamping forming die.

As such stamping forming die, specifically can use by the stamping forming die main body 52,62 after from stamping forming die 50,60, guiding parts 54,64 being omitted consist of without the stamping forming die of leading-portion type or stamping forming die main body 52,62 and guiding parts 54, opened the stamping forming die 50,60 of the divergence type that consists of in 64 minutes.In addition, in the situation that use the stamping forming die 50,60 of divergence type, in the second stamping procedure, only promote stamping forming die main body 52 towards arrow X1 direction, and only promote stamping forming die main body 62 towards arrow X2 direction, thus plate glass 26 is applied stamping pressure.

-taking-up operation-

Take out operation after having passed through the second stamping procedure, take out in operation at this, the first stamping forming die 50 is separated with the second stamping forming die 60, thereby the plate glass 26 that will be clamped between the first stamping forming die 50 and the second stamping forming die 60 take out.This taking-up operation for example can be implemented according to following illustrated mode.

At first, as shown in Figure 8, the first stamping forming die 50 is moved towards arrow X2 direction, and the second stamping forming die 60 is moved towards arrow X1 direction, thereby the first stamping forming die 50 and the second stamping forming die 60 are separated from each other.Thus, drawing face 62A is separated with plate glass 26.

Then, as shown in Figure 9, make drawing face 52A separate (demoulding) with plate glass 26, plate glass 26 is fallen towards the below of vertical direction Y1 side, thereby plate glass 26 is taken out.In addition, when the drawing face of making 52A separates (demoulding) with plate glass 26, thereby the mode that the power that can apply according to the peripheral direction from plate glass 26 is peeled off plate glass 26 is separated (demoulding).In this situation, need not that plate glass 26 is applied larger power and just plate glass 26 can be taken out.In addition, when taking out operation, can be also to separate (demoulding) to make afterwards drawing face 62A separate (demoulding) with plate glass 26 with plate glass 26 at the drawing face of making 52A.

At last, as required the plate glass 26 that takes out is carried out annealing in process and reduces or remove warpage, thus obtain for processing magnetic recording media glass substrate mother metal, be glass blank.

-glass blank-

The flatness of the glass blank that the manufacture method of the glass blank by First embodiment discussed above obtains can reach (in 10 μ m) below 10 μ m, and to reach 4 μ m following (in 4 μ m) be also extremely to be easy to.In addition, from omitting or shortening grinding process etc. take the viewpoint of the rear operation improving flatness and implement as fundamental purpose, flatness is preferably at (in 4 μ m) below 4 μ m.

In addition, the manufacture method of the glass blank of First embodiment is suitable for making the glass blank that thickness of slab is thinner and flatness is good.Be suitable for specifically making thickness of slab and be the following and flatness of 2mm at the glass blank of (in 10 μ m) below 10 μ m.Preferred thickness of slab is below 1.5mm, and further preferred thickness of slab is below 1.2mm, and further preferred thickness of slab is below 1.0mm.

-stamping forming die-

As consisting of stamping forming die 50,60 material, be preferably metal or alloy when considering thermotolerance, processibility, permanance.In this situation, when considering the temperature of melten glass, consist of the heat resisting temperature of stamping forming die 50,60 metal or alloy preferably more than 1000 ℃, more preferably more than 1100 ℃.As consisting of stamping forming die 50,60 material, be preferably specifically spheroidal-graphite cast iron (FCD), alloy tool steel (SKD61 etc.), high-speed steel (SKH), superhard alloy, colmonoy and stellite etc.In addition, when carrying out drawing, also the heat eliminating mediums such as water or air are carried out to stamping forming die 50,60 cooling, thereby suppress stamping forming die 50,60 temperature raises.

In addition, for Temperature Distribution in the face that makes drawing face 52A, 62A becomes even, also can utilize heat eliminating medium to carry out cooling near the position central portion of drawing face 52A, 62A, and/or, at the heater block of stamping forming die 50,60 outer circumferential side configuration well heater etc., the peripheral edge side of drawing face 52A, 62A is heated.

In addition, the zone that contacts with plate glass 26 at least (melten glass elongated area S1, S2) for drawing face 52A, the 62A of the first stamping forming die 50 and the second stamping forming die 60, such as being the face that is formed with the larger jog such as protuberance, but, usually be preferably the face of general planar, wherein, the jog that raised part etc. is larger is used for forming the V-shaped valley etc. that its degree of depth is 1/4～1/3 left and right of thickness of slab on the surface of glass blank.

In addition, also the whole face of drawing face 52A, 62A can be formed the face of general planar.Its reason is: when being formed with larger V-shaped valley on glass blank, it is by the concentrated rift defect that causes of the stress of V-shaped valley part that easy generation is presumed to.In addition, when being formed with larger jog in melten glass elongated area S1, S2, can hinder plate glass 26 thermal shrinkage diametrically in the second stamping procedure.Therefore, produce too much stress on the in-plane of plate glass 26, thereby easily cause plate glass 26 to break.

At this, should " face of general planar " except usually said curvature in fact is 0 tabular surface, also refer to form a little the face of the very little curvature of having of convex surface or concave surface.In addition, have on " face of general planar " that small concavo-convex yes allows, also can arrange as required and compare this small concavo-convex larger protuberance and/or recess, wherein, above-mentioned small concavo-convexly form when implementing common smoothing processing or mirror ultrafinish processing etc. in making the drawing mold process.

At this, about comparing small concavo-convex larger protuberance, so long as cause resistance to flow to reduce or promote that the little and height of the cooling possibility of the locality of fused glass block is below 20 μ m, protuberance that be point-like and/or be in fact wire in fact is allowed to.In addition, these are highly preferably below 10 μ m, more preferably below 5 μ m.

In addition, be not to be in fact point-like and to be in fact wire when comparing small concavo-convex larger protuberance, but the minimum widith of its end face is several millimeters or other trapezoidal protuberance of exceedance grade or when having dome-shaped protuberance with the height of this trapezoidal protuberance same degree and size, due to as described above, cause resistance to flow to reduce or promote the cooling possibility of locality of fused glass block to diminish, therefore, as long as its height is allowed to below 50 μ m.In addition, these are highly preferably below 30 μ m, more preferably below 10 μ m.

In addition, produce the viewpoint in crack because the bottom surface of trapezoidal protuberance is concentrated with the intersection point stress partly of side from suppressing, it is 0.5 spend with the plane of lower angle or this planar shaped become the curved surface of concave surface that the side of trapezoidal protuberance is preferably its angle of inclination with respect to end face.In addition, this angle is more preferably below 0.1 degree.

In addition, about comparing small concavo-convex larger recess, so long as its degree of depth to be 20 μ m following is in fact point-like and/or is in fact the recess of wire, thereby flow into the situation of the mobility variation etc. of the melten glass in this recess in the time of can drawing occuring, be allowed to.In addition, this degree of depth is preferably below 10 μ m, more preferably below 5 μ m.

In addition, be not to be in fact point-like and to be in fact wire when comparing small concavo-convex larger recess, but the minimum widith of its end face is several millimeters or other inverted trapezoidal recess of exceedance grade or has and the degree of depth of this inverted trapezoidal recess same degree and when falling the dome-like recessed portion of size, because the possibility of mobility variation that causes as described above diminishes, therefore, as long as its degree of depth is allowed to below 50 μ m.In addition, this degree of depth is preferably below 30 μ m, more preferably below 10 μ m.

In addition, produce the viewpoint in crack because the bottom surface of inverted trapezoidal recess is concentrated with the intersection point stress partly of side from suppressing, it is 0.5 spend with the plane of lower angle or this planar shaped become the curved surface of concave surface that the side of inverted trapezoidal recess is preferably its angle of inclination with respect to the bottom surface.In addition, this angle is more preferably below 0.1 degree.

In the manufacture method of the glass blank of First embodiment, as mentioned above, can utilize (1) to be one-piece type stamping forming die 50,60, (3) stamping forming die main body 52,62 and the guiding parts 54 that consists of integratedly, the stamping forming die 50 of opening the divergence type of formation in 64 minutes, 60 etc. without stamping forming die, (2) stamping forming die main body 52,62 and the guiding parts 54,64 of leading-portion type as stamping forming die.In the stamping forming die of this three types, from realizing simultaneously with the state of tool balance the viewpoint of higher flatness and less thickness deviation, most preferably use the stamping forming die 50,60 of divergence type.

At this, the stamping forming die 50,60 of divergence type is the preferred stamping forming die with structure shown below that uses specifically.Namely, the stamping forming die 50 of divergence type (perhaps stamping forming die 60) preferably is provided with stamping forming die main body 52, guiding parts 54, the first push mechanism and the second push mechanism at least, wherein, stamping forming die main body 52 has the drawing face 52A substantially vertical with horizontal direction; Guiding parts 54 has following function at least, namely, contacted with the part of another stamping forming die 60 when and another stamping forming die 60 sides configuration opposite with drawing face 52A promote when drawing, thereby the distance between a pair of stamping forming die 50,60 drawing face 52A, 62A is remained the distance of roughly fixing; The first push mechanism promotes stamping forming die main body 52 and guiding parts 54 along the direction substantially vertical with drawing face 52A simultaneously towards another stamping forming die 60 sides; The second push mechanism promotes stamping forming die main body 52 along the direction substantially vertical with drawing face 52A towards another stamping forming die 60 sides after making guiding parts 54 by the first push mechanism and the part of another stamping forming die 60 contacts.

Figure 10 means the mode sectional drawing of an example of the stamping forming die that uses in the manufacture method of magnetic recording media glass substrate with glass blank of First embodiment, specifically represents the stamping forming die 50 of divergence type, the figure of an example of 60.In Figure 10, for giving identical symbol with the parts that Fig. 4～parts shown in Figure 9 are identical.In addition, stamping forming die 50S shown in Figure 10 is corresponding with stamping forming die 50, and stamping forming die 60 also can adopt identical structure.

At this, the major part of stamping forming die 50S is made of stamping forming die main body 52, guiding parts 54, the first push mechanism 56 and the second push mechanism 58.The central shaft of each parts (illustrating with dot-and-dash line X in figure) is consistent, and central shaft is roughly consistent with horizontal direction.

At this, stamping forming die main body 52 is made of right cylinder, the conglobate drawing face 52A of this cylindrical end face structure.In addition, in example shown in Figure 10, the shape of stamping forming die main body 52 is cylindric, still, its shape so long as roughly cylindrical shape just be not particularly limited.In example shown in Figure 10, drawing face 52A forms the face of general planar.

Guiding parts 54 is made of cylinder, this cylinder is long in the length of stamping forming die main body 52 on axial X that the Length Ratio on axial X is made of right cylinder, and in it, all sides contain stamping forming die main body 52, and, when being promoted by the first push mechanism 56, an end face (spigot surface 54A) of this cylinder contacts with the guiding parts (not shown in figure) that consists of another stamping forming die.

At this, the length of guiding parts 54 on axial X and stamping forming die main body 52 length on axial X poor, spigot surface 54A and the difference of height H of drawing face 52A on axial X are equivalent to the roughly length of half of prepared glass blank thickness of slab in other words.In addition, the shape of guiding parts 54 is cylindric, still, its shape so long as tubular just be not particularly limited.

The first push mechanism 56 is made of disc-shaped part.At this, a face of this discoid the first push mechanism 56 (promote face 56A) is the tabular surface formation that is contacted by the other end (being pushed face 54B) with the other end (being pushed face 52B) of stamping forming die main body 52 and guiding parts 54.In addition, the first push mechanism 56, with a part of zone in the face that the is pushed 52B opposite zone of stamping forming die main body 52 in be provided with through hole 56H, this through hole 56H through-thickness runs through the first push mechanism 56.

In addition, the face 56B that promotes the opposition side of face 56A is connected with not shown the first drive unit.Therefore, when carrying out drawing, can by this first drive unit and via the first push mechanism 56 along the axial X in figure from disposing the first push mechanism 56 sides towards disposing stamping forming die main body 52 and guiding parts 54 sides promote stamping forming die main body 52 and guiding parts 54 simultaneously.

In addition, in example shown in Figure 10, the shape of the first push mechanism 56 is in the form of annular discs, and still, its shape is so long as roughly tabularly just be not particularly limited.In addition, through hole 56H is set to have the hole of circular open along the central shaft X of stamping forming die main body 52 and the first push mechanism 56, but, can the first push mechanism 56, with a part of zone in the face that the is pushed 52B opposite zone of stamping forming die main body 52 in the optional position on the through hole 56H of any amount is set.In addition, the opening shape of through hole 56H also can be selected aptly.But through hole 56H especially preferably is arranged to be point symmetry with respect to the central shaft X of stamping forming die main body 52.

The second push mechanism 58 is by being configured in through hole 56H and the bar-like member that is connected with the face that the is pushed 52B side of stamping forming die main body 52 consists of.In addition, in example shown in Figure 10, the second push mechanism 58 forms columniform bar-shaped, still, as long as can make stamping forming die main body 52 vertically X move, just its shape is not particularly limited.

In addition, the second push mechanism 58, be pushed opposition side end that face 52B side is connected an end and be connected with not shown the second drive unit.Therefore, when carrying out drawing, can by this second drive unit and via the second push mechanism 58 vertically X only promote stamping forming die main body 52 from disposing the second push mechanism 58 sides towards disposing stamping forming die main body 52 sides.

-glass material-

The glass material that uses in manufacture method as the glass blank of First embodiment, so long as have the physical property that is suitable for the magnetic recording media glass substrate, especially high thermal expansion coefficient and then high rigidity or thermotolerance etc., and easily drawing is tabular material by the direct punching press of level, just is not particularly limited.About thermal expansivity, preferably approach the thermal expansivity of the retainer that keeps magnetic recording media.Specifically, the average coefficient of linear expansion under 100 ℃～300 ℃ is preferably 70 * 10 ^-7/ ℃ more than, more preferably 75 * 10 ^-7/ ℃ more than, further preferably 80 * 10 ^-7/ ℃ more than, further preferably 85 * 10 ^-7/ ℃ more than.The higher limit of average coefficient of linear expansion is not particularly limited, still, from point of view of practicability preferably 120 * 10 ^-7/ ℃ below.

The deflection aspect that produces when reducing the magnetic recording media High Rotation Speed, the glass material of high rigidity preferably, specifically, Young modulus is preferably more than 70GPa, more preferably more than 75GPa, further preferably more than 80GPa, further preferably more than 85GPa.The higher limit of Young modulus is not particularly limited, still, from point of view of practicability preferably below 120GPa.

And then; by using the outstanding glass material of thermotolerance; can carry out pyroprocessing to substrate in the process of making magnetic recording media; therefore; the vitrification point of glass material is preferably more than 600 ℃; more preferably more than 610 ℃, further preferably more than 620 ℃, further preferably more than 630 ℃.In addition, the higher limit of vitrification point is not particularly limited, and still, the temperature during from the inhibition drawing becomes the practical aspects such as high temperature, preferably below 780 ℃.Use has high thermal expansion coefficient, high rigidity, stable on heating glass material concurrently, is effective for the glass substrate of the magnetic recording media that obtains being suitable for high record density.

Composition as glass material, can select aptly easily realization to be suitable for the composition of the physical property of magnetic recording media glass substrate, for example, can select aptly the glass of the glass material that uses in existing vertical directly punching press to form, but, preferred alumina silicate glass (alumino-silicate glass).In addition, about alumina silicate glass, from easily having the aspect that has evenly thermotolerance, high rigidity and high thermal expansion coefficient concurrently, especially be preferably composition shown below.

That is, in the situation that represent with molar percentage, the glass composition of this glass (below, be called " glass forms 1 ") comprising: 50%～75% SiO ₂, 0%～5% Al ₂O ₃, 0%～3% Li ₂O, 0%～5% ZnO, amount to 3%～15% the Na that is selected from ₂O and K ₂At least a composition of O, the ZrO that is selected from that amounts to 14%～35% at least a composition that is selected from MgO, CaO, SrO and BaO and amount to 2%～9% ₂, TiO ₂, La ₂O ₃, Y ₂O ₃, Yb ₂O ₃, Ta ₂O ₅, Nb ₂O ₅And HfO ₂At least a composition, and, mol ratio { (MgO+CaO)/(MgO+CaO+SrO+BaO) } in 0.8～1 scope, mol ratio { Al ₂O ₃/ (MgO+CaO) } in 0～0.30 scope.

The preferable range of the average coefficient of linear expansion under 100 ℃～300 ℃ of glass composition 1 is 70 * 10 ^-7/ ℃ more than, the preferable range of vitrification point is more than 630 ℃, the preferable range of Young modulus is more than 80GPa.Glass forms 1 and is suitable as and uses that high Ku (magnetic anisotropy energy) is magnetic material, the material of the magnetic recording media glass substrate power assist mode.

As have high thermal expansion coefficient, acid resistance and alkali resistance good, separate out less and be suitable for chemical enhanced glass material from the alkali of substrate surface, can enumerate and have the material that following glass forms (below, be called " glass forms 2 ").That is, in the situation that represent with molar percentage, glass forms 2 and comprises: amount to 70%～85% SiO ₂And Al ₂O ₃(wherein, SiO ₂Amount be more than 50%, Al ₂O ₃Amount be more than 3%), amount to the Li more than 10% ₂O, Na ₂O and K ₂O, amount to 1%～6% MgO and CaO (wherein, the amount of CaO is more than the amount of MgO) and amount to the ZrO that surpasses below 0% and 4% ₂, TiO ₂, La ₂O ₃, Y ₂O ₃, Yb ₂O ₃, Ta ₂O ₅, Nb ₂O ₅And HfO ₂

(manufacture method of magnetic recording media glass substrate)

The manufacture method of the magnetic recording media glass substrate of First embodiment is characterised in that, the grinding step that grinds through the first type surface of glass blank that the manufacture method of the glass blank by the First embodiment is made is at least made the magnetic recording media glass substrate.Below, thereby in further detail the concrete example of glass blank being processed each operation when making the magnetic recording media glass substrate is described.

At first, the glass blank that drawing is obtained rule (scribe).So-called " line " refers to: the scriber that utilization is made by superhard alloy or emery arranges the line of cut (wire score) of two concentric circless (inner concentric circle and outer concentric circle) shape on the surface of glass blank, forms the ring-type of given size with the glass blank after being shaped.Heat part for the glass blank that is scribed ss two concentric circles, thereby utilize the difference that glass heat expands and the Outboard Sections of outer concentric circle and the inboard part of inner concentric circle are removed, and thus, forms the disk-shaped glass of positive toroidal.

In addition, when the external diameter of the outside dimension under the glass blank state and final magnetic recording media glass substrate (glass substrate for disc) is roughly the same (in the time of only just size can being revised by end surface grinding described later), also can replace crossed process and to the central part that becomes circular hole of glass blank core (coring).

The roughness of glass blank first type surface adds man-hour ruling, as long as just can use scriber that line of cut is set aptly below 1 μ m.In addition, when the roughness of glass blank first type surface surpasses 1 μ m, sometimes scriber can't follow (imitateing) thus concave-convex surface is difficult to similarly arrange line of cut.In this situation, rule after the first type surface smoothing that makes glass blank.

Then, the glass after line is carried out shape processing.Shape processing comprises chamfering (chamfering of peripheral end and interior all ends).When carrying out chamfering, utilize skive to implement chamfering to peripheral end and interior all ends of ring-type glass.

Then, disk-shaped glass is carried out end surface grinding.When carrying out end surface grinding, grind by hairbrush interior all side end faces and the outer circumference side edge face of glass are carried out minute surface finishing.At this moment, use the slurry that contains the particulates such as cerium oxide as free abrasive particle.Thereby remove the damage of pollution, damage or the scuffing etc. of adhering to dust etc. on the glass end face by carrying out end surface grinding, the ion that can prevent from thus becoming the sodium of corrosion or potassium etc. is separated out.

Then, the first type surface of disk-shaped glass being implemented first grinds.The first purpose of grinding is to remove scar, the warpage that remains on first type surface.The first process redundancy that grinds is for example for about number μ m～10 μ m.Owing to can carrying out the large grinding process of process redundancy, therefore, scar that can be in generation grinding process on glass, warpage etc.Therefore, the process redundancy in the first grinding step is little also can.

Use double-side polishing apparatus in the first grinding step and the second grinding step described later.Thereby double-side polishing apparatus is the device that uses grinding pad and grind by disk-shaped glass and grinding pad are relatively moved.Double-side polishing apparatus has to grind uses planet carrier installation portion and top lap and lower abrasive disk, wherein, this grinding has annular wheel and the sun gear that is driven in rotation with the rotating ratio of stipulating respectively with the planet carrier installation portion, this top lap and lower abrasive disk are driven with the mode of the mutual reverse rotation of planet carrier installation portion to clip this grinding.Top lap and lower abrasive disk with opposed of disk-shaped glass on post respectively grinding pad described later.Carry out the planet wheel motion with the grinding of installing with the mode of annular wheel and sun gear engagement with planet carrier, thereby rotation is on one side revolved round the sun around sun gear on one side.

Grinding is with maintaining respectively a plurality of disk-shaped glass on planet carrier.Top lap can move towards above-below direction, thereby with on the first type surface of grinding pad by the surface that is pressed in disk-shaped glass and the back side.Then, supply with on one side and contain the slurry (lapping liquid) that grinds abrasive particle (abrasive material), carry out the planet wheel motion and make top lap and lower abrasive disk carry out reverse rotation disk-shaped glass and grinding pad are relatively moved by making to grind with planet carrier on one side, thereby the surface of disk-shaped glass and the first type surface at the back side are ground.In addition, in the first grinding step, use for example hard resin abrasive disk as grinding pad, use for example cerium oxide abrasive particle as abrasive material.

Then, carry out chemical enhanced to the disk-shaped glass after grinding through first.Can use fuse salt such as potassium nitrate etc. as chemical enhanced liquid.Carrying out when chemical enhanced, the glass after chemical enhanced liquid being heated to for example 300 ℃～400 ℃, cleaning is preheated to after for example 200 ℃～300 ℃, and glass was soaked in chemical enhanced liquid for example 3 hours～4 hours.When carrying out this immersion, carry out under the state during preferably maintained mode is accommodated in retainer with end face at multiple pieces of glass, so that two first type surface integral body of glass are by chemical enhanced.

Thus, by with glass immersion in chemical enhanced liquid, the sodion of surface layer of glass is by the displacement of the relatively large potassium ion of the ionic radius in chemical enhanced liquid, thereby forms approximately 50 μ m～200 thick compressive stress layers of μ m.Thus, thus glass is reinforced and possesses good impact resistance.In addition, the glass after chemical enhanced processing is cleaned.For example, after utilizing sulfuric acid cleaned, utilize pure water, IPA (isopropyl alcohol) etc. to clean.

Then, grind being implemented second by the glass after chemical enhanced and abundant cleaning.The second process redundancy that grinds is for for example about 1 μ m.

The second purpose of grinding is first type surface is finish-machined to mirror-like.In the second grinding step, similarly use double-side polishing apparatus that disk-shaped glass is ground with the first grinding step, still, in the lapping liquid that uses (slurry), the composition of contained grinding abrasive particle and grinding pad is different.Compare with the first grinding step, the particle diameter of the grinding abrasive particle that uses in the second grinding step is less, and the hardness of grinding pad is softer.For example, in the second grinding step, use for example flexible foam resin ground dish as grinding pad, use such as than the more tiny cerium oxide abrasive particle of the cerium oxide abrasive particle that uses in the first grinding step or silica gel etc. as abrasive material.

Polished disk-shaped glass in the second grinding step is cleaned again.Use neutral lotion, pure water, IPA during cleaning.Grind by second, obtain the flatness of first type surface for example at the glass substrate for disc of roughness (Ra) below 0.2nm of (in 4 μ m) and first type surface below 4 μ m.Then, form the various layers of (film forming) magnetosphere etc. on glass substrate for disc, thereby make disk.

In addition, chemical enhanced operation is to carry out between the first grinding step and the second grinding step, but is not limited to this order.So long as carry out the second grinding step after the first grinding step, just can configure aptly chemical enhanced operation.For example, can be also the order (below, be called " process sequence 1 ") of the first grinding step, the second grinding step, chemical enhanced operation.But, in process sequence 1, owing to can't removing issuable concave-convex surface in chemical enhanced operation, therefore, the process sequence of the first grinding step, chemical enhanced operation, the second grinding step more preferably.

In addition, when making the magnetic recording media glass substrate, also can make the flatness of the glass blank that uses in processing identical in fact with the flatness of prepared magnetic recording media glass substrate.Its reason is: in recent years, about to the desired flatness of magnetic recording media glass substrate, for example require its flatness at (in 10 μ m) below 10 μ m for the glass substrate of 2.5 inches, and the glass blank that the manufacture method of the glass blank by the First embodiment is made can easily reach above-mentioned flatness.

At this, so-called " flatness of the glass blank that uses in processing is identical in fact with the flatness of prepared magnetic recording media glass substrate " refers to: in the time will being made as 100% for the desired flatness of magnetic recording media glass substrate (glass substrate for disc), the flatness of glass blank is below 105%.

In addition, when the flatness of the flatness of the glass blank that uses in processing and prepared magnetic recording media glass substrate is identical in fact, can omit the operation that grinding process etc. is implemented as one of fundamental purpose to improve flatness.

(manufacture method of magnetic recording media)

The manufacture method of the magnetic recording media of First embodiment is characterised in that, forms operation through the magnetic recording layer that forms magnetic recording layer on the magnetic recording media glass substrate of making in the manufacture method of the magnetic recording media glass substrate by the First embodiment at least and makes magnetic recording media.

Magnetic recording media is called as disk, hard disk etc., and it is suitable for desk-top computer, server with the internal storage (fixed disk etc.) of computing machine, notebook computer, portable computer etc., with the internal storage of the potable recording regenerating unit of image and/or SoundRec regeneration, the record regenerator of vehicle audio etc.

Magnetic recording media for example can form following such structure; namely; on the first type surface of magnetic recording media glass substrate, from beginning to be laminated with at least successively adhesion layer, basalis, magnetosphere (magnetic recording layer), protective seam, lubricating layer near this first type surface one side.For example, the magnetic recording media glass substrate is imported in the film formation device of vacuum, and utilize direct current magnetron sputtering process to form successively (film forming) adhesion layer to magnetospheric various layers under argon gas atmosphere on the first type surface of magnetic recording media glass substrate.For example CrTi can be used as adhesion layer, for example CrRu can be used as basalis.After above-mentioned film forming, for example utilize CVD (chemical vapor deposition) method and use C ₂H ₄(ethene) gas forms (film forming) protective seam, and effects on surface imports the nitrogen treatment of nitrogen in same chamber, can form magnetic recording media thus.Then, utilize dip coating to apply for example PFPE (PFPE) on protective seam, can form lubricating layer thus.

Size for magnetic recording media is not particularly limited, but, because the magnetic recording media glass substrate is to be made of the outstanding glass material of impact resistance, therefore, be preferably the large size below 2.5 inches or 2.5 inches of possibility of being convenient to carry and suffer external impact.

The＜the second present embodiment 〉

(magnetic recording media glass substrate with the manufacture method of glass blank and the manufacturing installation that uses thereof)

the manufacture method of the magnetic recording media glass substrate use glass blank of the second present embodiment (below, sometimes referred to as " manufacture method of glass blank "), at least through the drawing operation make the magnetic recording media glass substrate with glass blank (below, sometimes referred to as " glass blank "), wherein, in this drawing operation, utilize the first stamping forming die and the second stamping forming die to carry out drawing to the fused glass block in falling, this first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with this fused glass block intersects.

At this, the at least the first stamping forming die is provided with stamping forming die main body and guiding parts at least, wherein, this stamping forming die main body has drawing face, this guiding parts has following function at least, namely, when drawing by when and second stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of the second stamping forming die configuration contact, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained the distance of roughly fixing.

And, the drawing operation comprises first step and second step, in first step, make the first stamping forming die and the second stamping forming die mutually near until the guiding parts of the first stamping forming die contact with the second stamping forming die, thus fused glass block is configured as plate glass, in second step, under the guiding parts of the first stamping forming die and state that the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press.

At this, in the first step of drawing operation, make the first stamping forming die and the second stamping forming die mutually close.Therefore, fused glass block is plate glass by the first stamping forming die and the second stamping forming die drawing.In addition, by making the first stamping forming die and the second stamping forming die mutually close, thereby the guiding parts of the first stamping forming die is contacted with the second stamping forming die.Therefore, at this moment, the distance between the drawing face of the first stamping forming die and the second stamping forming die is retained as roughly fixing distance.Therefore, can make the thickness deviation of the plate glass under state between the drawing face of being clamped in become very little.Therefore, also can make the thickness deviation of the glass blank that finally obtains very little.

But, after first step just finishes under soon state, hold yielding state thereby plate glass is in high temperature and mobility is high.Therefore, thus in the situation that first step just makes the first stamping forming die and the second stamping forming die be separated from each other the plate glass taking-up after just having finished soon, all not by any parts carry, thereby plate glass easily is out of shape due to the two sides of plate glass.The flatness variation of the glass blank that therefore, makes.

Therefore, think after first step finishes, the state that preferably also guiding parts and second stamping forming die of the first stamping forming die is in contact with one another is kept a period of time, thereby the drawing face of utilization is supported the two sides of plate glass.Its reason is: think to make plate glass cooling preventing the plate glass distortion with the state that utilizes drawing face that the two sides of plate glass is supported when, and in the situation that the mobility of plate glass reduces or lose after with its taking-up, can suppress the flatness variation of glass blank.

But, can shrink in absorbing the process be cooled thereby the plate glass that contacts with drawing face is stamped into shape mould at its heat.Therefore, in the situation that first step also continues to keep first step after finishing just finished after distance between soon drawing face, produce the gap between drawing face and plate glass.Therefore, consider the contraction of plate glass, be difficult to utilize drawing face to support the two sides of plate glass always.Therefore, even the state that further guiding parts and second stamping forming die of the first stamping forming die is in contact with one another after first step finishes is kept a period of time, also be difficult to the inhibition plate glass and deform.

Yet, in second step, under the guiding parts of the first stamping forming die and state that the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press.That is, further further continue plate glass is carried out punching press near the mode of the drawing face side of the second stamping forming die according to the stamping forming die main body that only makes the first stamping forming die.

Therefore, even plate glass shrinks at its thickness direction, drawing face also always with seamless unoccupied place, the two sides of plate glass close contact, thereby the two sides of plate glass is supported.Therefore, thereby in the situation that with the state that utilizes as mentioned above drawing face always the two sides of plate glass to be supported the cooling mobility of plate glass is reduced or lose after take out, can suppress more reliably the flatness variation of glass blank.

In addition, in second step, the drawing face of the stamping forming die that is made of higher than the solid components of the gases such as air that exist in the gap coefficient of heat conductivity and plate glass be seamless unoccupied place close contact all the time, therefore, can effectively absorb by stamping forming die the heat of plate glass.Therefore, and compare forming gapped situation between drawing face and plate glass, can further impel the mobility of the plate glass in drawing to reduce.Therefore, when plate glass separates with drawing face when finishing (second step), thereby plate glass is the lower state that is out of shape or can not be out of shape of being difficult to of mobility.Therefore, from this viewpoint, the plate glass after drawing also is difficult to deform, thereby can further dwindle the flatness of glass blank.

In addition, in the manufacture method of the glass blank of the second present embodiment, can be also that only the first stamping forming die is provided with stamping forming die main body and guiding parts at least.In this situation, the second stamping forming die is such as stamping forming die that can use the column that consists of drawing face by an end face to consist of etc.In this situation, in first step, the guiding parts of the first stamping forming die contacts with the drawing face of the second stamping forming die.Then, in second step, under the guiding parts of the first stamping forming die and state that the drawing face of the second stamping forming die contacts, utilize the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press (below, sometimes such process for stamping and forming is called " the first Sheet Metal Forming Technology ").

in addition, in the manufacture method of the glass blank of the second present embodiment, can be also that the first stamping forming die and the second stamping forming die are provided with respectively stamping forming die main body and guiding parts at least, wherein, the stamping forming die main body has drawing face, guiding parts has following function at least, namely, when drawing by when and stamping forming die side configuration opposite with drawing face promotes, with opposite with drawing face and the part of stamping forming die configuration contacts, thus the distance between the drawing face of the first stamping forming die and the second stamping forming die is remained roughly fixing distance.

In this situation, first step is implemented by following manner, that is, make the first stamping forming die and the second stamping forming die mutually close, until the guiding parts of the first stamping forming die contacts with the guiding parts of the second stamping forming die.And, second step is implemented by following manner, namely, under the guiding parts of the first stamping forming die and state that the guiding parts of the second stamping forming die contacts, utilize the stamping forming die main body of the stamping forming die main body of the first stamping forming die and the second stamping forming die further to continue plate glass is carried out punching press (below, sometimes such process for stamping and forming is called " the second Sheet Metal Forming Technology ").

In addition, aspect the enforcement of second step, that use in any technique of the first Sheet Metal Forming Technology and the second Sheet Metal Forming Technology, stamping forming die that be provided with at least stamping forming die main body and guiding parts, especially preferably have stamping forming die main body and guiding parts can be separately towards and another stamping forming die side shifting configuration opposite with it.

The manufacture method of the glass blank of the second present embodiment can be implemented by any technique of the first Sheet Metal Forming Technology and the second Sheet Metal Forming Technology.But, aspect the glass blank of the thickness deviation that obtains having same degree and flatness, can further shorten the required time of drawing from comparing the first Sheet Metal Forming Technology, for example can foreshorten to the viewpoint of 1/3 left and right of the first Sheet Metal Forming Technology required time, especially preferably implement by the second Sheet Metal Forming Technology.Its reason is: compare with the first Sheet Metal Forming Technology, the structure of a pair of stamping forming die that uses in the second Sheet Metal Forming Technology is more similar or identical, therefore, can implement cooling from the two sides to the plate glass between a pair of stamping forming die more symmetrically.

The manufacture method of the glass blank of the second present embodiment discussed above as long as comprise that at least the drawing operation just is not particularly limited, still, usually preferably includes fused glass block and forms operation.In addition, after through the drawing operation, thereby implement to make the first stamping forming die to separate the taking-up operation that plate glass is taken out with the second stamping forming die.

Below, in further detail to comprising that fused glass block forms operation and describes with each operation of taking out operation.In addition, omitted in the following description explanation about above-mentioned described aspect.

-fused glass block formation operation-

Form in operation at fused glass block, make the fused glass block as the drawing object.Manufacture method for fused glass block is not particularly limited, normally thereby the leading section with molten glass flow cuts off the formation fused glass block, wherein, this molten glass flow makes melten glass hang down and flow out continuously and form towards the vertical direction lower side from the glass flows outlet.In addition, can cut off with a pair of shear-blade the leading section of molten glass flow.In addition, about the viscosity of melten glass, so long as be suitable for the cut-out of leading section or the viscosity of drawing just is not particularly limited, usually preferably be controlled to be the fixed value in 500dPas～1050dPas scope.In addition, be about to carry out the viscosity of drawing fused glass block before also preferably in above-mentioned scope.

Next, the concrete example that in further detail fused glass block is formed operation with reference to the accompanying drawings describes.

Form in operation at fused glass block, as shown in figure 11, molten glass flow 120 flows out the bottom of pipe 110 from being arranged at melten glass glass flows outlet 112 lower side towards vertical direction are flowed out continuously, wherein, this melten glass upper end of flowing out pipe 110 is connected with not shown melten glass supply source.

On the other hand, both sides on the lower side of glass flows outlet 112 and molten glass flow 120, substantially vertical with the central shaft D of the direction that hangs down of molten glass flow 120 direction dispose respectively the first shear-blade (lower blade) 130 and the second shear-blade (upper blade) 140.And, lower blade 130 and upper blade 140 move towards arrow X1 direction and arrow X2 direction respectively, thus from the both sides of molten glass flow 120 near leading section 122 sides of molten glass flow 120, wherein, arrow X1 direction is vertical with central shaft D and be to advance towards the right side from the left side in the drawings, and arrow X2 direction is vertical with central shaft D and be to advance towards the left side from the right side in the drawings.In addition, the temperature that flows out the melten glass supply source of pipe 110 or its upstream by regulating melten glass is controlled the viscosity of molten glass flow 120.

In addition, lower blade 130 and upper blade 140 have roughly tabular main part 132,142 and blade part 134,144, this blade part 134,144 is arranged on main part 132,142 end side, and the leading section 122 of the molten glass flow 120 that will flow out continuously towards the vertical direction lower side from the direction substantially vertical with the direction that hangs down of molten glass flow 120 cuts off.

In addition, the upper surface 134U of blade part 134 and the lower surface 144B of blade part 144 form and surface level consistent face roughly, and the lower surface 134B of blade part 134 and the upper surface 144U of blade part 144 form the face that tilts in the mode that intersects with surface level.In addition, lower blade 130 and upper blade 140 are configured to: the upper surface 134U of blade part 134 and the lower surface 144B of blade part 144 are on the height and position of roughly the same degree with respect to vertical direction.

Then, as shown in figure 12, according to by lower blade 130 and upper blade 140 are further moved towards arrow X1 direction and arrow X2 direction respectively, thereby the lower surface 144B part of the upper surface 134U of blade part 134 and blade part 144 is the mode that overlaps of seamless unoccupied place almost, make lower blade 130 and upper blade 140 respectively along continuous straight runs move.That is, lower blade 130 and upper blade 140 are vertically intersected with respect to central shaft D.

Thus, lower blade 130 and upper blade 140 are inserted near the position of central shaft D of molten glass flow 120, thereby leading section 122 is cut into roughly spherical fused glass block 124.In addition, Figure 12 represents that leading section 122 is with the form of fused glass block 124 state from the main part time of releasing of molten glass flow 120.And as shown in figure 13, the fused glass block 124 after cutting off from molten glass flow 120 further falls towards the below of vertical direction Y1 side.

-drawing operation (first step)-

In first step, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block 124 in whereabouts shown in Figure 13 is configured as it tabular, wherein, this first stamping forming die and the second stamping forming die arranged opposite on the direction that the falling direction with fused glass block 124 intersects.At this, the first stamping forming die and the second stamping forming die are preferably with arranged opposite, especially preferably arranged opposite on the direction vertical with the falling direction of fused glass block 124 on the mode that forms 90 degree ± 1 degree angles with the falling direction of fused glass block 124 and the substantially vertical direction of the falling direction of fused glass block 124.Thus, by a pair of stamping forming die of falling direction arranged opposite with respect to fused glass block 124, being more prone to from both sides is tabular with fused glass block 124 drawings equably.

In addition, be about to implement the temperature of drawing face before first step, the first stamping forming die and the second stamping forming die, preferably below the temperature of the strain point of the glass material that consists of fused glass block 124+10 ℃, more preferably below the temperature of the strain point of the glass material that consists of fused glass block 124+5 ℃.By with the temperature setting of drawing face in above-mentioned scope, can suppress more reliably fused glass block 124 and drawing face generation welding when drawing.

The lower limit that is about to implement drawing surface temperature before first step, the first stamping forming die and the second stamping forming die is not particularly limited, but, cause glass blank to break, prevent from preventing because of the quenching of fused glass block 124 because viscosity sharply increases and the remarkable viewpoint of the practical aspect such as reductions of the extensibility that causes fused glass block 124 during drawing, preferably more than the strain point of the glass material of formation fused glass block 124.

In addition, be about to implement the absolute value of difference of temperature of drawing face of the temperature of drawing face before first step, the first stamping forming die and the second stamping forming die preferably in the scope of 0 ℃～10 ℃, more preferably in the scope of 0 ℃～5 ℃, especially be preferably 0 ℃.In this situation, can be suppressed at more reliably on the two sides that is formed tabular plate glass by fused glass block 124 being carried out punching press and produce temperature difference, thereby can further improve flatness.

In addition, the absolute value that is about to implement temperature difference in the face of drawing face before first step, the first stamping forming die and the second stamping forming die preferably in the scope of 0 ℃～100 ℃, more preferably in the scope of 0 ℃～50 ℃, especially is preferably 0 ℃.By the Temperature Distribution in drawing face is located in above-mentioned scope, be more prone to make fused glass block 124 to extend into equably when drawing lamellar.Consequently, even in the situation that the thinner glass blank of manufacturing thickness of slab also is more prone to obtain flatness well and the also little glass blank of thickness deviation.

Need to prove the temperature that so-called " face of drawing face in temperature " measured in referring to when drawing drawing face and extending into the maximum region that tabular fused glass block 124 contacts.

Then, more specifically first step is described with reference to the accompanying drawings.

At first, as shown in figure 14, fused glass block 124 shown in Figure 13 enters between first stamping forming die 150 and the second stamping forming die 160 of arranged opposite on the direction vertical with the falling direction Y1 of fused glass block 124.At this, implement drawing the first stamping forming die 150 before and be configured to the second stamping forming die 160: line is symmetrical and mode that be separated from each other on the direction vertical with falling direction Y1 is opposite to be with respect to falling direction Y1.

Then, thereby carry out drawing from both sides extrusion molten glass blocks 124 opportunity of position in order to arrive near central portion on the vertical direction of the first press forming dies 150 and the second press forming die 160 with fused glass block 124 with matching, make the first stamping forming die 150 towards vertical with falling direction Y1 and be that the arrow X1 direction of advancing towards the right side from the left side moves in the drawings, make the second stamping forming die 160 towards vertical with falling direction Y1 and be that the arrow X2 direction of advancing towards the left side from the right side moves in the drawings.

In addition, the translational speed that moves towards arrow X2 direction of the translational speed that moves towards arrow X1 direction of the first stamping forming die 150 and the second stamping forming die 160 is set to identical or roughly the same.

At this, stamping forming die 150,160 has and is roughly discoid stamping forming die main body 152,162 and guiding parts 154,164, and this guiding parts 154,164 is configured to this stamping forming die main body 152,162 outer circumference end are surrounded.In addition, because Figure 14 is sectional view, therefore, is depicted as guiding parts 154,164 and is positioned at stamping forming die main body 152,162 both sides up and down in Figure 14.In addition, omitted in the drawings about making stamping forming die 150 move, make the record of the driver part that stamping forming die 160 moves towards arrow X2 direction towards arrow X1 direction.

Stamping forming die main body 152, a face of 162 become drawing face 152A, 162A.And in Figure 14, the first stamping forming die 150 and the second stamping forming die 160 are configured in the relative mode of separately drawing face 152A, 162A opposite.In addition, guiding parts 154 is being provided with spigot surface 154A with respect to drawing face 152A on the height and position that the X1 direction is given prominence to a little, guiding parts 164 is being provided with spigot surface 164A with respect to drawing face 162A on the height and position that the X2 direction is given prominence to a little.Therefore, when carrying out drawing, spigot surface 154A and spigot surface 164A connect, thereby are formed with the gap between drawing face 152A and drawing face 162A.Therefore, the width in this gap is the thickness that is stamped into shape as tabular fused glass block 124, is the thickness of glass blank between the first stamping forming die 150 and the second stamping forming die 160.

In addition, drawing face 152A, 162A are formed: thus make between the drawing face 162A of fused glass block 124 at the drawing face 152A of the first stamping forming die 150 and the second stamping forming die 160 vertically when the extruding expansion is shaped as plate glass fully by implementing first step, and the zone that contacts with above-mentioned plate glass at least (melten glass elongated area) S1, the S2 of drawing face 152A, 162A are the face of general planar.

In addition, in example shown in Figure 14, comprise that it is 0 tabular surface that the drawing face 152A of melten glass elongated area S1 and the whole face that comprises the drawing face 162A of melten glass elongated area S2 form usually said curvature in fact.In addition, only exist small concavo-convex and do not exist and compare this small concavo-convex larger protuberance and/or recess on this tabular surface, wherein, this is small concavo-convex formed concavo-convex when referring to implement common smoothing processing or mirror ultrafinish processing etc. in making the drawing mold process.

Glass blank utilizes drawing face 152A, 162A extrusion molten glass blocks 124 to carry out drawing and make.Therefore, the surfaceness of the surfaceness of drawing face 152A, 162A and glass blank first type surface is almost identical.From carrying out the line processing of implementing as rear operation described later and the grinding aspect of carrying out with diamond chip, the surfaceness of glass blank first type surface (center line average roughness Ra) is preferably in the scope of 0.01 μ m～10 μ m, therefore, the surfaceness of drawing face (center line average roughness Ra) is also preferred in the scope of 0.01 μ m～10 μ m.

Fused glass block 124 shown in Figure 14 further falls towards the below, and enters between two drawing face 152A, 162A.Then, as shown in figure 15, near arriving substantial middle section on the above-below direction of drawing face 152A, the 162A parallel with falling direction Y1, fused glass block 124 during the position, the both side surface of fused glass block 124 is contacted with drawing face 152A, 162A.At this moment, preferred drawing face 152A roughly contacts with fused glass block 124 simultaneously as shown in figure 15 with drawing face 162A.

At this, so-called " roughly simultaneously contact " refers to: the absolute value of the mistiming between the time point that fused glass block contacts with a drawing face and fused glass block and time point that another drawing face contacts is in 0.1 second.The absolute value of this mistiming more preferably in 0.05 second, most preferably is 0 second (simultaneously).

In addition, as a reference, in vertical directly impact style, after contacting with the drawing face of counterdie from fused glass block to fused glass block so that with time required till the drawing face of patrix contacts, although also the condition according to drawing is different and different, generally about 1.5 seconds～3 seconds.

In addition, preferred drawing face 152A roughly contacts with fused glass block 124 simultaneously as shown in figure 15 with drawing face 162A, and, at least in during enforcement drawing operation, the temperature of the drawing face 152A of the first stamping forming die 150 is identical in fact with the temperature of the drawing face 162A of the second stamping forming die 160.Thus, the two sides that is shaped as the fused glass block 124 in tabular process and is clamped in the plate glass under state between a pair of stamping forming die 150,160 in first step in second step is continued cooling all the time symmetrically.

In this situation, with for comparing because produced the vertical direct punching press that fused glass block under the state of viscosity profile carries out drawing with the counterdie Long contact time, almost do not produce temperature difference on the two sides of the plate glass after drawing, thereby can suppress more reliably to cause because of the temperature difference on two sides flatness to reduce.

At this, so-called " identical in fact " refers to: the absolute value of the temperature difference of the temperature of the drawing face 162A of the temperature of the drawing face 152A of the first stamping forming die 150 and the second stamping forming die 160 is in 10 ℃.The absolute value of this temperature difference more preferably in 5 ℃, most preferably is 0 ℃.In addition, in the situation that have Temperature Distribution in drawing face 152A, 162A, so-called " temperature of drawing face " refers near the temperature of the position central part of drawing face.

In addition, as a reference, in vertical directly impact style, the absolute value of the temperature difference between the drawing face of the patrix when fused glass block being carried out drawing and the drawing face of counterdie, although also the condition according to drawing is different and different, generally 50 ℃～100 ℃ left and right.

In addition, become because the viscosity of the fused glass block 124 in falling increases when also considering when being difficult to carry out drawing or causing stamping position to produce the viewpoint of change because falling speed becomes too fast, distance of fall is preferably selected in the scope below 1000mm, more preferably select in the scope below 500mm, further select in preferred scope below 300mm, most preferably select in the scope below 200mm.In addition, the lower limit of distance of fall is not particularly limited, but from point of view of practicability preferably more than 100mm.

Need to prove, should " distance of fall " refer to: from as leading section as illustrated in Figure 12 122 with the form of fused glass block 124 separated moment, position that to be lower blade 130 overlap in vertical direction with upper blade 140 extremely as illustrated in Figure 15 begin to carry out drawing the time (beginning to carry out the moment of drawing) the substantial middle section that makes progress of the footpath of position, drawing face 152A, the 162A parallel with falling direction Y1 near distance till the position.

Then, as shown in figure 16, when utilizing the first stamping forming die 150 and the second stamping forming die 160 to continue extrusion molten glass blocks 124 from both sides, fused glass block 124 is extruded expansion with uniform thickness centered by fused glass block 124 and position that drawing face 152A, 162A begin to contact most.Then, utilize the first stamping forming die 150 and the second stamping forming die 160 to continue to push, until spigot surface 154A contacts with spigot surface 156A as shown in figure 17, form thus discoid between drawing face 152A, 162A or discoid plate glass 126 roughly.

At this, plate glass 126 shown in Figure 17 has shape and the thickness identical in fact with the glass blank that finally obtains.And the size and dimension on plate glass 126 two sides is consistent with the size and dimension of melten glass elongated area S1, S2 (not shown in Figure 17).In addition, from making the viewpoint of fused glass block 124 thin plates, state when beginning from drawing shown in Figure 15 becomes the required time of state that spigot surface 154A shown in Figure 17 contacts with spigot surface 164A (below, be sometimes referred to as " drawing time ") preferably in 0.1 second.

In addition, when carrying out drawing, spigot surface 154A and spigot surface 164A are contact condition, thereby easily keep the parastate of drawing face 152A and drawing face 162A.In addition, the lower limit of drawing time is not particularly limited, but from point of view of practicability preferably more than 0.05 second.

In addition, as Figure 14～shown in Figure 17, stamping forming die 150 has stamping forming die main body 152 and guiding parts 154, and stamping forming die 160 also has identical structure.At this, in first step, stamping forming die main body 152 is integratedly with guiding parts 154 and moves towards arrow X1 direction simultaneously, and stamping forming die main body 162 is integratedly with guiding parts 164 and moves towards arrow X2 direction simultaneously.

In addition, because stamping forming die 150,160 has respectively guiding parts 154,164, therefore, and under guiding parts 154 as shown in figure 17 and state that guiding parts 164 contacts, drawing face 152A and drawing face 162A keeping parallelism.Therefore, even as Figure 14～stamping forming die 150 is moved towards arrow X1 direction, make stamping forming die 160 drawing face 152A and drawing face 162A in the process that arrow X2 direction moves to keep parastate, also easily make the thickness deviation of the glass blank that obtains very little.Therefore, and do not require and drive the control ability that stamping forming die 150,160 drive unit have the exquisiteness of carrying out following control, that is, make drawing face 152A and drawing face 162A keep all the time parastate accurately in Figure 14～series of processes shown in Figure 17.

-drawing operation (second step)-

In second step, under the guiding parts 154 of the first stamping forming die 150 as shown in figure 17 and state that the guiding parts 164 of the second stamping forming die 160 contacts, the stamping forming die main body 152 that drives the first stamping forming die 150 moves towards arrow X1 direction, and the stamping forming die main body 162 that drives the second stamping forming die 160 moves towards arrow X2 direction.Thus, utilize stamping forming die main body 152,162 further to continue plate glass 126 is carried out punching press.

In addition, thus the high mobility of temperature high (viscosity is low) of plate glass 126 after first step has just finished soon.That is, thus plate glass is in very easily the state of the easy variation of distortion flatness.Therefore, in the situation that not sufficiently cooled with plate glass 126 and state that keep high fluidity finishes second step, after second step finishes, thus the flatness variation that plate glass 126 might deform and cause glass blank.Therefore, preferably continue to carry out second step until the temperature of plate glass 126 to be reduced at least the temperature of the strain point of the glass material that consists of plate glass 126+10 ℃ following.Namely, preferably after keeping first step shown in Figure 17 and just having finished in soon state, utilize stamping forming die main body 152 and stamping forming die main body 162 to continue plate glass 126 is carried out punching press, until that the temperature of plate glass 126 is reduced to the temperature of the strain point of the glass material that consists of plate glass 126+10 ℃ is following.

In this situation, thereby plate glass 126 is continued the punching press temperature range that in fact the mobility forfeiture can not deform until plate glass 126 is sufficiently cooled.That is, can be after keeping first step and just having finished make plate glass 126 sclerosis in soon the repressed state of distortion of plate glass 126.Therefore, can make the flatness of the glass blank that makes become better.

At this, the mode that preferably reaches (in 10 μ m) below 10 μ m according to the flatness of glass blank is controlled the duration of second step, and the mode that more preferably reaches (in 10 μ m) below 4 μ m according to the flatness of glass blank is controlled the duration of second step.In addition, when duration of second step more in short-term, can cause because of disturbance the plate glass 126 generation warpages in cooling procedure, this warpage easily causes the flatness variation of glass blank.Therefore, change the duration of second step, and the flatness of resulting glass blank is measured, when the flatness after it is measured reaches (in 10 μ m) below 10 μ m, be set as the duration of second step its duration, make thus glass blank comparatively desirable.

But the long meeting of the duration of second step causes throughput rate to reduce, thereby preferably sets the duration of second step after the flatness of considering glass blank and throughput rate.From the point of view, the duration of second step is preferred in the scope of 2 seconds～40 seconds, more preferably in the scope of 2 seconds～30 seconds specifically.

In addition, in second step, especially preferably select in the following manner the duration of second step, control to (in 10 μ m) below 10 μ m with the flatness with glass blank, wherein, aforesaid way refers to: thus continue plate glass is carried out punching press until the temperature of plate glass is reduced to the mobility of plate glass loses in the temperature range that in fact can not deform.In this situation, can be after keeping first step and just having finished make plate glass 126 sclerosis in soon the repressed state of distortion of plate glass 126.Therefore, can make the flatness of the glass blank that makes better.

At this, about the duration of second step, the mode that the temperature of the plate glass when preferably finishing according to second step becomes below the temperature of the strain point of the glass material that consists of plate glass+10 ℃ is selected, the mode that more preferably becomes below the temperature of strain point+5 ℃ according to the temperature of above-mentioned plate glass is selected, and further preferably selects according to the mode of temperature below strain point of above-mentioned plate glass.On the other hand, the lower limit temperature of the temperature of the plate glass when second step finishes is not particularly limited, but, the viewpoint that causes throughput rate to reduce because implement the second step required time to increase from suppressing, from point of view of practicability preferably more than strain point.Therefore, the higher limit of the duration of second step is also preferably selected from this viewpoint.

In addition, in during till when finishing to second step soon after the first step that contacts with fused glass block 124 from drawing face 152A, 162A has just begun, the temperature of the glass between drawing face 152A and drawing face 162A (fused glass block 124 and plate glass 126), although the difference of the glass material that also uses according to drawing and difference is generally significantly to be reduced to 480 ℃ ± 20 ℃ left and right from 1200 ℃ ± 50 ℃ left and right.Therefore, in second step, be accompanied by that temperature reduces so significantly and thermal shrinkage occurs plate glass 126 diametrically.And, in the situation that continue to carry out second step until the temperature of plate glass 126 reach low temperature more temperature range, especially consist of the temperature range below the temperature of the strain point of the glass material of plate glass 126+10 ℃, above-mentioned thermal shrinkage is more remarkable.

On the other hand, think in second step, thereby thereby the heat that the drawing face 152A, the 162A that contact with the two sides of plate glass 126 continue to absorb plate glass 126 has absorbed enough heats and no longer absorbs heat and stop on in-plane thermal expansion or transfer thermal shrinkage slowly in thermal expansion on in-plane or from plate glass 126.

That is, in second step, between the two sides and drawing face 152A, 162A of plate glass 126, the thermal expansion between two parts or the degree of thermal shrinkage are different.Therefore, in second step, by drawing face 152A, 162A, the two sides of the plate glass 126 in the thermal shrinkage process is applied the power wanting plate glass 126 is radially expanded, namely is reverse power with the thermal shrinkage direction.But, in second step, due to the mobility reduction of the plate glass 126 along with the carrying out of second step, therefore, plate glass 126 is applied too much stress easily causes plate glass 126 that brittle fractures occur.Therefore, apply when being reverse power with the thermal shrinkage direction when continue two sides to plate glass 126 always, produce too much stress on the in-plane of plate glass 126, thereby cause plate glass 126 to break.

In order to prevent breaking of plate glass 126 as described above, consider that (1) is as consisting of stamping forming die 150,160 material, use thermal expansivity to approach the material of the thermal expansivity of the glass material that consists of plate glass 126, and, (2) in second step, the temperature of plate glass 126 and the temperature of drawing face 152A, 162A are synchronously reduced.But, owing to being attended by significantly temperature variation in second step, therefore, want to implement as described above cooling, cooling velocity must be very little.But, in this situation, because the enforcement required time of second step significantly increases, therefore, lack practicality thereby might cause mass productivity significantly to reduce.

Consider aspect discussed above, preferably time dependent ground reduces stamping pressure in second step, breaks in second step to prevent more reliably plate glass 126.In this situation, along with reducing stamping pressure, the friction factor between the two sides of plate glass 126 and drawing face 152A, 162A reduces.So, produce between the two sides of plate glass 126 and drawing face 152A, 162A and slide, thus easily interrupt two sides to plate glass 126 apply become the reason of breaking be reverse power with the thermal shrinkage direction.

At this, so-called " time dependent ground reduction stamping pressure " not only is included in the situation that reduces stamping pressure in second step along with the process of time, also comprise following situation, namely, even the situation that stamping pressure temporarily increases or keep fixed value occurs along with the process of time, but its gradient is negative value when stamping pressure is similar to linear function with respect to the variation of time.In addition, stamping pressure can be reduced along with the process of time interimly, also stamping pressure can be reduced continuously along with the process of time.

In addition, in the situation that reduce stamping pressure along with the process of time interimly, reduction stamping pressure in the time of preferably in the temperature that is clamped in the plate glass 126 between the first stamping forming die 150 and the second stamping forming die 160 is reduced to the yield point of the glass material that consists of plate glass 126 ± 30 ℃ scope.Thus, can more effectively suppress breaking of plate glass 126 by the operation of fairly simple stamping pressure.In addition, in this situation, from making the state that breaks and suppress the flatness variation that suppresses reliably plate glass 126 have the viewpoint that realizes simultaneously evenly, in the time reducing front stamping pressure and be made as 100%, the stamping pressure after reduction is preferably in the scope of 1%～60% left and right.

-taking-up operation-

Taking out operation through after second step, take out in operation at this, the first stamping forming die 150 is separated with the second stamping forming die 160, and the plate glass 126 that will be clamped in thus between the first stamping forming die 150 and the second stamping forming die 160 takes out.This taking-up operation for example can be implemented according to following illustrated mode.

At first, as shown in figure 18, the first stamping forming die 150 is moved towards arrow X2 direction, the second stamping forming die 160 is moved towards arrow X1 direction, thereby the first stamping forming die 150 and the second stamping forming die 160 are separated from each other, drawing face 162A is separated with plate glass 126.

Then, as shown in figure 19, make drawing face 152A separate (demoulding) with plate glass 126, plate glass 126 is fallen towards the below of vertical direction Y1 side, thereby plate glass 126 is taken out.In addition, when the drawing face of making 152A separates (demoulding) with plate glass 126, thereby the mode that the power that can apply according to the peripheral direction from plate glass 126 is peeled off plate glass 126 is separated (demoulding).In this situation, need not that plate glass 126 is applied larger power and just it can be taken out.In addition, when taking out operation, can be also to separate (demoulding) to make afterwards drawing face 162A separate (demoulding) with plate glass 126 with plate glass 126 at the drawing face of making 152A.

At last, reduce or remove warpage thereby as required the plate glass 126 that takes out is carried out annealing in process, obtaining thus for the mother metal of processing the magnetic recording media glass substrate, be glass blank.

-glass blank-

The flatness of the glass blank that the manufacture method of the glass blank by the second present embodiment discussed above obtains can reach for example (in 10 μ m) below 10 μ m, and to reach 4 μ m following (in 4 μ m) be also extremely to be easy to.In addition, from omitting or shortening grinding process etc. take the viewpoint of the rear operation improving flatness and implement as fundamental purpose, flatness is preferably at (in 4 μ m) below 4 μ m.

In addition, the manufacture method of the glass blank of the second present embodiment also is suitable for making the glass blank that thickness of slab is thinner and flatness is good.Be suitable for specifically making thickness of slab and be the following and flatness of 2mm at the glass blank of (in 10 μ m) below 10 μ m.Preferred thickness of slab is below 1.5mm, and further preferred thickness of slab is below 1.2mm, and further preferred thickness of slab is below 1.0mm.

-stamping forming die-

The stamping forming die 150 that uses in the manufacture method of the glass blank of the second present embodiment has stamping forming die main body 152 and guiding parts 154 at least.And stamping forming die 160 also has stamping forming die main body 162 and guiding parts 164 at least, and it has the structure same with stamping forming die 150.Below, describe as an example of stamping forming die 150 example.

At first, the stamping forming die main body 152 of stamping forming die 150 and guiding parts 154 are separately to consist of.Therefore, in first step, can drive stamping forming die main body 152 and guiding parts 154 is integratedly towards opposite with it and stamping forming die 160 sides configuration move, and, in second step, can only drive with respect to guiding parts 154 stamping forming die main body 152 relatively towards opposite with it and the configuration stamping forming die 160 sides move.Thereby, because stamping forming die 150 has above-mentioned 26S Proteasome Structure and Function, therefore, can further dwindle thickness deviation and the flatness of glass blank.

In addition, in the situation that only pay attention to dwindle thickness deviation, can utilize stamping forming die main body 152 and guiding parts 154 to be the stamping forming die that forms.But, in the situation that utilize such stamping forming die, make stamping forming die main body 152 relatively towards opposite with it and stamping forming die 160 sides configuration move thereby can't only drive stamping forming die main body 152 with respect to guiding parts 154.Therefore, even continue to keep the state that guiding parts 154 contacts with guiding parts 164 after first step finishes, thus the two sides that also can't make drawing face 152A, 162A and plate glass 126 all the time seamless unoccupied place close contact the two sides of plate glass 126 is supported.Therefore, the easy variation of the flatness of glass blank.

In addition, in the situation that only pay attention to the reduced plan degree, can utilize the stamping forming die (without the shaping die of guiding parts) with guiding parts 154.In the situation that utilize such stamping forming die, even after fused glass block 124 drawings are plate glass 126, thus the two sides that also can make drawing face 152A, 162A and plate glass 126 all the time seamless unoccupied place close contact the two sides of plate glass 126 is supported.But, owing to there not being guiding parts 154,164, therefore, must extremely critically drive stamping forming die, otherwise be difficult to drawing face 152A and drawing face 162A exactly the state of keeping parallelism carry out drawing.Therefore, the thickness deviation of glass blank easily becomes large.

Consider above illustrated aspect, at least be provided with the guiding parts 154 that separately consists of and the stamping forming die 150 (with stamping forming die 160) of stamping forming die main body 152, can have the thickness deviation that improves evenly glass blank and flatness the two aspect very favourable.

As consisting of stamping forming die 150,160 material, consider its thermotolerance, processibility, permanance and be preferably metal or alloy.In this situation, when considering the temperature of melten glass, consist of the heat resisting temperature of stamping forming die 150,160 metal or alloy preferably more than 1000 ℃, more preferably more than 1100 ℃.As consisting of stamping forming die 150,160 material, be preferably specifically spheroidal-graphite cast iron (FCD), alloy tool steel (SKD61 etc.), high-speed steel (SKH), superhard alloy, colmonoy, stellite etc.In addition, when carrying out drawing, also the heat eliminating mediums such as water or air are carried out to stamping forming die 150,160 cooling, thereby suppress stamping forming die 150,160 temperature raises.

In addition, in order to make the Temperature Distribution in drawing face 152A, 162A face become even, also can utilize heat eliminating medium to carry out cooling near the position central portion of drawing face 152A, 162A, and/or, thereby heat at the peripheral edge side of the heater blocks such as stamping forming die 150,160 outer circumferential side configuration well heater to drawing face 152A, 162A.

In addition, the zone that contacts with plate glass 126 at least of drawing face 152A, the 162A of the first stamping forming die 150 and the second stamping forming die 160 (melten glass elongated area S1, S2), such as being the face that is formed with the larger jog such as protuberance, but, usually be preferably the face of general planar, wherein, the jog that raised part etc. is larger is used for forming the V-shaped valley etc. that its degree of depth is 1/4～1/3 left and right of thickness of slab on the surface of glass blank.

In addition, also the whole face of drawing face 152A, 162A can be formed the face of general planar.Its reason is: when being formed with larger V-shaped valley on glass blank, easily being presumed to is by the concentrated rift defect that causes of the stress of V-shaped valley part.In addition, when being formed with larger jog in melten glass elongated area S1, S2, can hinder that in second step, plate glass 126 carries out thermal shrinkage diametrically.Therefore, produce too much stress on the in-plane of plate glass 126, thereby easily cause plate glass 126 to break.

At this, should " face of general planar " except usually said curvature in fact is 0 tabular surface, also refer to form a little the face of the very little curvature of having of convex surface or concave surface.In addition, have on " face of general planar " that small concavo-convex yes allows, also can arrange as required and compare this small concavo-convex larger protuberance and/or recess, wherein, above-mentioned small concavo-convex be formed when making the common smoothing processing of stamping forming die implementation Process or mirror ultrafinish processing etc.

At this, about comparing small concavo-convex larger protuberance, so long as cause resistance to flow to reduce or promote that the cooling possibility of the locality of fused glass block is little and be highly below 20 μ m, be point-like and/or be in fact the protuberance of wire in fact, be allowed to.In addition, these are highly preferably below 10 μ m, more preferably below 5 μ m.

In addition, be not to be in fact point-like and to be in fact wire when comparing small concavo-convex larger protuberance, but the minimum widith of its end face is several millimeters or other trapezoidal protuberance of exceedance grade or when having dome-shaped protuberance with the height of this trapezoidal protuberance same degree or size, cause resistance to flow to reduce or promote the cooling possibility of locality of fused glass block to diminish due to as described above, therefore, as long as its height is allowed to below 50 μ m.In addition, these are highly preferably below 30 μ m, more preferably below 10 μ m.

In addition, produce the viewpoint in crack because the bottom surface of trapezoidal protuberance is concentrated with the intersection point stress partly of side from suppressing, the side of trapezoidal protuberance be preferably formed for its angle of inclination with respect to end face be 0.5 spend with the plane of lower angle or this planar shaped become the curved surface of concave surface.In addition, this angle is more preferably below 0.1 degree.

In addition, about comparing small concavo-convex larger recess, so long as thereby the degree of depth recess that to be 20 μ m following is in fact point-like and/or is in fact wire flows into the situation of the mobility variation of the melten glass in this recess etc. can drawing not occur the time, be to be allowed to.In addition, this degree of depth is preferably below 10 μ m, more preferably below 5 μ m.

In addition, be not to be in fact point-like and to be in fact wire when comparing small concavo-convex larger recess, but the minimum widith of its end face is several millimeters or other inverted trapezoidal recess of exceedance grade or when having the recess of falling the cheese with the degree of depth of this inverted trapezoidal recess same degree or size, because the possibility of mobility variation that causes as described above diminishes, therefore, as long as its degree of depth is allowed to below 50 μ m.In addition, this degree of depth is preferably below 30 μ m, more preferably below 10 μ m.

In addition, produce the viewpoint in crack because the bottom surface of inverted trapezoidal recess is concentrated with the intersection point stress partly of side from suppressing, the side of inverted trapezoidal recess be preferably formed for its angle of inclination with respect to the bottom surface be 0.5 spend with the plane of lower angle or this planar shaped become the curved surface of concave surface.In addition, this angle is more preferably below 0.1 degree.

In addition, as Figure 14～shown in Figure 19, stamping forming die 150 (with stamping forming die 160) is as long as have at least stamping forming die main body 152 and guiding parts 154 and can implement first step and second step, its concrete structure just is not particularly limited, but, preferably also be provided with the first push mechanism and the second push mechanism except stamping forming die main body 152 and guiding parts 154.At this, the first push mechanism has along the direction vertical with drawing face 152A at least towards opposite with drawing face 152A and stamping forming die 160 sides configuration promote the function of stamping forming die main body 152 and guiding parts 154 simultaneously.In addition, the second push mechanism has following function at least, namely, make by the first push mechanism guiding parts 154 with after the part (guiding parts 164) of the opposite stamping forming die that configures 160 of drawing face 152A contacts, along the direction vertical with drawing face 152A towards opposite with drawing face 152A and stamping forming die 160 sides configuration promote stamping forming die main bodys 152.

Figure 20 means the mode sectional drawing of an example of the stamping forming die that uses in the manufacture method of magnetic recording media glass substrate with glass blank of the second present embodiment, specifically represents the figure of an example of stamping forming die 150,160 more concrete structure.In Figure 20, for giving identical symbol with the parts that Figure 14～parts shown in Figure 19 are identical.In addition, stamping forming die 150S shown in Figure 20 is corresponding with stamping forming die 150, and stamping forming die 160 also can adopt same structure.

At this, the major part of stamping forming die 150S is made of stamping forming die main body 152, guiding parts 154, the first push mechanism 156 and the second push mechanism 158.The central shaft of each parts (illustrating with dot-and-dash line X in figure) is consistent, and central shaft is roughly consistent with horizontal direction.

At this, stamping forming die main body 152 is made of right cylinder, the conglobate drawing face 152A of this cylindrical end face structure.In addition, in example shown in Figure 20, the shape of stamping forming die main body 152 is cylindric, still, its shape so long as roughly cylindrical shape just be not particularly limited.In example shown in Figure 20, drawing face 152A forms the face of general planar.

Guiding parts 154 is made of cylinder, Length Ratio on the axial X of this cylinder is long by the length of stamping forming die main body 152 on axial X that right cylinder consists of, and in it, all sides contain stamping forming die main body 152, and an one end face (spigot surface 154A) contacts with the guiding parts (not shown in figure) that consists of another stamping forming die when being promoted by the first push mechanism 156.At this, the length of guiding parts 154 on axial X and stamping forming die main body 152 length on axial X poor, spigot surface 154A and the difference of height H of drawing face 152A on axial X are equivalent to the roughly length of half of prepared glass blank thickness of slab in other words.In addition, the shape of guiding parts 154 is cylindric, still, its shape so long as tubular just be not particularly limited.

The first push mechanism 156 is made of disc-shaped part.At this, the tabular surface formation that a face of this discoid the first push mechanism 156 (promote face 156A) is contacted by the other end (being pushed face 154B) with the other end (being pushed face 152B) of stamping forming die main body 152 and guiding parts 154.In addition, the first push mechanism 156, with a part of zone in the face that the is pushed 152B opposite zone of stamping forming die main body 152 in, be provided with the through hole 156H that through-thickness runs through the first push mechanism 156.In addition, the face 156B that promotes the opposition side of face 156A is connected with not shown the first drive unit.Therefore, when carrying out drawing, can by this first drive unit and via the first push mechanism 156 along the axial X in figure from disposing the first push mechanism 156 sides towards disposing stamping forming die main body 152 and guiding parts 154 sides promote stamping forming die main body 152 and guiding parts 154 simultaneously.

In addition, in example shown in Figure 20, the shape of the first push mechanism 156 is in the form of annular discs, and still, its shape is so long as roughly tabularly just be not particularly limited.In addition, through hole 156H is along the central shaft X of stamping forming die main body 152 and the first push mechanism 156 and be set to have the hole of circular open, but, can the first push mechanism 156, with the face that the is pushed 152B opposite zone of stamping forming die main body 152 in the optional position in part zone on the through hole 156H of any amount is set.

In addition, the opening shape of through hole 156H also can be selected aptly.But through hole 156H especially preferably is set to be point symmetry with respect to the central shaft X of stamping forming die main body 152.

The second push mechanism 158 is by being configured in through hole 156H and the bar-like member that is connected with the face that the is pushed 152B side of stamping forming die main body 152 consists of.In addition, in example shown in Figure 20, the second push mechanism 158 is cylindrical bar-shaped, still, as long as can make stamping forming die main body 152 vertically X move, just its shape is not particularly limited.

In addition, the second push mechanism 158, be connected with not shown the second drive unit with the opposition side end that is pushed a end that face 152B side is connected.Therefore, when carrying out drawing, can by this second drive unit and via the second push mechanism 158 vertically X only promote stamping forming die main body 152 from disposing the second push mechanism 158 sides towards disposing stamping forming die main body 152 sides.

In addition, when carrying out drawing, extend into equably thin plate in order easily to make fused glass block 124, preferably the Temperature Distribution in drawing face 152A face is controlled to be uniform Temperature Distribution.For this reason, (1) heater block that near the position peripheral edge side of drawing face 152A is heated can be set, and/or (2) can arrange the cooling runner with medium of circulation near the position central portion at least of the inside of stamping forming die main body 152 and drawing face 152A side.

At this, as heater block, for example can be the equally spaced configuration heater air flow pressure switch rod parallel with axial X at the well heater of the outer circumferential side of guiding parts 154 configuration tubular or along the circumferencial direction of guiding parts 154.In addition, above-mentioned well heater can be built in guiding parts 154, also can be configured according to the mode of the outer peripheral face side of imbedding stamping forming die main body 152.In addition, as coolingly can utilize the gases such as liquid, air such as water with liquid, gas after the liquid spraying is disperseed etc.

In addition, also can utilize the illustrated stamping forming die of Figure 21 as stamping forming die 150,160.Figure 21 represents another routine mode sectional drawing of the stamping forming die that uses in the manufacture method of magnetic recording media glass substrate with glass blank of the second present embodiment.In addition, in Figure 21, give same-sign for the parts with or similar functions identical in fact with parts shown in Figure 20.

At this, the major part of stamping forming die 200 shown in Figure 21 is made of stamping forming die main body 152, guiding parts 154, the first push mechanism 156 and the second push mechanism 158.The central shaft of each parts (illustrating with dot-and-dash line X in figure) is consistent, and central shaft is roughly consistent with horizontal direction.In addition, stamping forming die 200 shown in Figure 21 and stamping forming die 150S shown in Figure 20 be provided with on stamping forming die main body 152, guiding parts 154, the first push mechanism 156 and the second push mechanism 158 this point identical, mainly following different on some.

namely, compare with stamping forming die 150S shown in Figure 20, in stamping forming die shown in Figure 21 200, (1) stamping forming die main body 152 is separated in fact with the inner peripheral surface of guiding parts 154 with the outer peripheral face that guiding parts 154 is configured to stamping forming die main body 152, (2) stamping forming die main body 152 is separated in fact with the promotion face 156A of the first push mechanism 156 with the face that the is pushed 152B that the first push mechanism 156 is configured to stamping forming die main body 152, (3) be pushed between face 152B and the face of promotion 156A, dispose support unit 170 along the outer circumferential side that is pushed face 152B.

At this, stamping forming die main body 152 is made of disc-shaped part, the conglobate drawing face 152A of an end face structure of this disc-shaped part.In addition, in example shown in Figure 20, the shape of stamping forming die main body 152 is in the form of annular discs, still, its shape so long as roughly plate-like just be not particularly limited.In example shown in Figure 21, drawing face 152A forms the face of general planar.In addition, support unit 170 is fixed and is configured on any face that is pushed in face 152B or the face of promotion 156A, and can separate with another face.In addition, support unit 170 is such as using endless member etc.

And, in stamping forming die shown in Figure 21 200, can utilize the first push mechanism 156 towards with stamping forming die 200 opposite and the configuration another stamping forming die thruster action-oriented parts 154.Meanwhile, also via support unit 170 towards opposite with stamping forming die 200 and another stamping forming die side configuration promotes stamping forming die main body 152.In addition, can utilize the second push mechanism 158 towards with stamping forming die 200 opposite and the configuration another stamping forming die side only promote stamping forming die main body 152.

In addition, in example shown in Figure 20, when carrying out drawing, be pushed near the central portion of face 152B position or (2) peripheral edge portion for (1) of stamping forming die main body 152 near the position apply pressing force.Therefore, preferably according to no matter to applying pressing force on which position shown in above-mentioned (1) and (2), the mode that stamping forming die main body 152 can deflection is yet selected the punching press condition of intensity of thickness, material, intensity of stamping forming die main body 152 etc., support unit 170 etc. or stamping pressure etc.

In addition, Figure 14～example shown in Figure 19 means the example of the second Sheet Metal Forming Technology, but, when implementing the first Sheet Metal Forming Technology, as long as stamping forming die example stamping forming die 150S as shown in figure 20 or stamping forming die 200 shown in Figure 21 in a pair of stamping forming die.In this situation, can utilize as another stamping forming die the aftermentioned stamping forming die (for example, stamping forming die shown in Figure 23 310 described later) that is consisted of by the stamping forming die main part of simple disk shaped part or columnar part etc. such as in fact only.

In this situation, for example in first step, the part of another stamping forming die (for example drawing face) contacts with spigot surface 154A, in second step, further promote stamping forming die main body 152 towards another stamping forming die side under the part of another stamping forming die and state that spigot surface 154A contacts.

-glass material-

The glass material that uses in manufacture method as the glass blank of the second present embodiment, so long as have physical property, especially high thermal expansion coefficient and then high rigidity or the thermotolerance etc. that are suitable for the magnetic recording media glass substrate, and easily be stamped into shape as tabular material by the direct punching press of level, just be not particularly limited.About thermal expansivity, preferably approach the thermal expansivity of the retainer that keeps magnetic recording media.Specifically, the average coefficient of linear expansion under 100 ℃～300 ℃ is preferably 70 * 10 ^-7/ ℃ more than, more preferably 75 * 10 ^-7/ ℃ more than, further preferably 80 * 10 ^-7/ ℃ more than, further preferably 85 * 10 ^-7/ ℃ more than.The higher limit of average coefficient of linear expansion is not particularly limited, still, from point of view of practicability preferably 120 * 10 ^-7/ ℃ below.

The warpage aspect that produces when reducing the magnetic recording media High Rotation Speed, the glass material of high rigidity preferably, specifically, Young modulus is preferably more than 70GPa, more preferably more than 75GPa, further preferably more than 80GPa, further preferably more than 85GPa.The higher limit of Young modulus is not particularly limited, and still, is preferably below 120GPa from point of view of practicability.

And then; can at high temperature process substrate in the process of making magnetic recording media owing to using the outstanding glass material of thermotolerance; therefore; the vitrification point of glass material is preferably more than 600 ℃; more preferably more than 610 ℃; further preferably more than 620 ℃, further preferably more than 630 ℃.In addition, the higher limit of vitrification point is not particularly limited, and still, the temperature when suppressing drawing becomes the practical point of view such as high temperature preferably below 780 ℃.It is effective for the glass substrate of the magnetic recording media that obtains being suitable for high record density that use has high thermal expansion coefficient, high rigidity, stable on heating glass material concurrently.

Composition as glass material, can select aptly easily to realize to be suitable for the composition of the physical property of magnetic recording media glass substrate, for example, can select aptly the glass of the glass material that uses in existing vertical directly punching press to form, but, preferred alumina silicate glass.In addition, as alumina silicate glass, realize simultaneously evenly thermotolerance, high rigidity and high thermal expansion coefficient owing to easily having, therefore, especially preferred composition shown below.

That is, in the situation that represent with molar percentage, the glass composition of this glass (below, be called " glass forms 1 ") comprising: 50%～75% SiO ₂, 0%～5% Al ₂O ₃, 0%～3% Li ₂O, 0%～5% ZnO, amount to 3%～15% the Na that is selected from ₂O and K ₂At least a composition of O, the ZrO that is selected from that amounts to 14%～35% at least a composition that is selected from MgO, CaO, SrO and BaO and amount to 2%～9% ₂, TiO ₂, La ₂O ₃, Y ₂O ₃, Yb ₂O ₃, Ta ₂O ₅, Nb ₂O ₅And HfO ₂At least a composition, and then, mol ratio { (MgO+CaO)/(MgO+CaO+SrO+BaO) } in 0.8～1 scope, and, mol ratio { Al ₂O ₃/ (MgO+CaO) } in 0～0.30 scope.

The preferable range of the average coefficient of linear expansion under 100 ℃～300 ℃ of glass composition 1 is 70 * 10 ^-7/ ℃ more than, the preferable range of vitrification point is more than 630 ℃, the preferable range of Young modulus is more than 80GPa.Glass composition 1 is suitable as the material of the power assist mode magnetic recording media glass substrate that uses high Ku magnetic material.

In addition, as have high thermal expansion coefficient, acid resistance and alkali resistance outstanding, separate out less and be suitable for chemical enhanced glass material from the alkali of substrate surface, can enumerate and have the material that following glass forms (being called " glass forms 2 ").

That is, in the situation that represent with molar percentage, glass forms 2 and comprises: amount to 70%～85% SiO ₂And Al ₂O ₃(wherein, SiO ₂Amount more than 50%, Al ₂O ₃Amount more than 3%), amount to the Li more than 10% ₂O, Na ₂O and K ₂O, amount to 1%～6% MgO and CaO (wherein, the amount of CaO is more than the amount of MgO) and amount to the ZrO that surpasses below 0% and 4% ₂, TiO ₂, La ₂O ₃, Y ₂O ₃, Yb ₂O ₃, Ta ₂O ₅, Nb ₂O ₅And HfO ₂

(manufacture method of magnetic recording media glass substrate)

The manufacture method of the magnetic recording media glass substrate of the second present embodiment is characterised in that, the grinding step that grinds through the first type surface of glass blank that the manufacture method of the glass blank by the second present embodiment is made is at least made the magnetic recording media glass substrate.Below, thereby in further detail the concrete example of glass blank being processed each operation when forming the magnetic recording media glass substrate is described.

At first, the glass blank that drawing is obtained is rule.So-called " line " refers to: the scriber that utilization is made by superhard alloy or emery arranges the line of cut (wire score) of two concentric circless (inner concentric circle and outer concentric circle) shape on the surface of glass blank, forms the ring-type of given size with the glass blank after being shaped.Heat part for the glass blank that is scribed ss two concentric circles, thereby utilize the thermal dilation difference of glass and the Outboard Sections of outer concentric circle and the inboard part of inner concentric circle are removed, and thus, forms the disk-shaped glass of positive toroidal.

The roughness of glass blank first type surface adds man-hour ruling, as long as just can use scriber that line of cut is set aptly below 1 μ m.In addition, when the roughness of glass blank first type surface surpasses 1 μ m, sometimes scriber can't follow (imitateing) thus concave-convex surface is difficult to similarly arrange line of cut.In this situation, rule after the first type surface smoothing that makes glass blank.

Then, the glass after line is carried out shape processing.Shape processing comprises chamfering (chamfering of peripheral end and interior all ends).When carrying out chamfering, utilize skive to implement chamfering to peripheral end and interior all ends of ring-type glass.

Then, disk-shaped glass is carried out end surface grinding.When carrying out end surface grinding, grind by hairbrush interior all side end faces and the outer circumference side edge face of glass are carried out minute surface finishing.At this moment, use the slurry that contains the particulates such as cerium oxide as free abrasive particle.Thereby remove the damage of pollution, damage or the scuffing etc. of adhering to dust etc. on the glass end face by carrying out end surface grinding, the ion that can prevent from thus becoming the sodium of corrosion or potassium etc. is separated out.

Then, the first type surface of disk-shaped glass being implemented first grinds.The first purpose of grinding is to remove scar, the warpage that remains on first type surface.The first process redundancy that grinds is for example for about number μ m～10 μ m.Owing to can carrying out the larger grinding process of process redundancy, therefore, the scar that produces in grinding process, warpage etc. of can not forming on glass.Therefore, the process redundancy in the first grinding step is little also can.

Use double-side polishing apparatus in the first grinding step and the second grinding step described later.Thereby double-side polishing apparatus is to use grinding pad and make disk-shaped glass and device that grinding pad relatively moves and grinds.Double-side polishing apparatus has to grind uses planet carrier installation portion and top lap and lower abrasive disk, wherein, this grinding has annular wheel and the sun gear that is driven in rotation with the rotating ratio of stipulating respectively with the planet carrier installation portion, this top lap and lower abrasive disk are driven with the mode of the mutual reverse rotation of planet carrier installation portion to clip this grinding.Top lap and lower abrasive disk with opposed of disk-shaped glass on post respectively grinding pad described later.Carry out the planet wheel motion with the grinding of installing with the mode of annular wheel and sun gear engagement with planet carrier, thereby rotation is on one side revolved round the sun around sun gear on one side.

Grinding is with maintaining respectively a plurality of disk-shaped glass on planet carrier.Top lap can move towards above-below direction, thereby with on the first type surface of grinding pad by the surface that is pressed in disk-shaped glass and the back side.Then, supply with on one side and contain the slurry (lapping liquid) that grinds abrasive particle (abrasive material), use the planet wheel motion of planet carrier and the reverse rotation of top lap and lower abrasive disk that disk-shaped glass and grinding pad are relatively moved by grinding on one side, thereby the surface of disk-shaped glass and the first type surface at the back side are ground.In addition, in the first grinding step, use for example hard resin abrasive disk as grinding pad, use for example cerium oxide abrasive particle as abrasive material.

Then, carry out chemical enhanced to the disk-shaped glass after the first grinding.Can use fuse salt such as potassium nitrate etc. as chemical enhanced liquid.Carrying out when chemical enhanced, the glass after chemical enhanced liquid being heated to for example 300 ℃～400 ℃, cleaning is preheated to after for example 200 ℃～300 ℃, and glass was soaked in chemical enhanced liquid for example 3 hours～4 hours.When this soaks, carry out under the state during preferably maintained mode is accommodated in retainer with end face at multiple pieces of glass, so that two first type surface integral body of glass are by chemical enhanced.

Thus, by with glass immersion in chemical enhanced liquid, the sodion of surface layer of glass is by the displacement of the relatively large potassium ion of the ionic radius in chemical enhanced liquid, thereby forms approximately 50 μ m～200 thick compressive stress layers of μ m.Thus, thus glass is reinforced and possesses good impact resistance.In addition, the glass after chemical enhanced processing is cleaned.For example, after utilizing sulfuric acid cleaned, utilize pure water, IPA (isopropyl alcohol) etc. to clean.

Then, grind being implemented second by the glass after chemical enhanced and abundant cleaning.The second process redundancy that grinds is for example about 1 μ m.

The second purpose of grinding is first type surface is finish-machined to mirror-like.In the second grinding step, similarly use double-side polishing apparatus that disk-shaped glass is ground with the first grinding step, still, in the lapping liquid of use (slurry), the composition of contained grinding abrasive particle and grinding pad is different.Compare with the first grinding step, the particle diameter of the grinding abrasive particle that uses in the second grinding step is less, and the hardness of grinding pad is softer.For example, in the second grinding step, use for example flexible foam resin ground dish as grinding pad, use for example more tiny than the cerium oxide abrasive particle that uses in the first grinding step cerium oxide abrasive particle as abrasive material.

Disk-shaped glass after grinding in the second grinding step is cleaned again.Use neutral lotion, pure water, IPA during cleaning.Grind by second, the flatness that obtains first type surface is below 4 μ m and the glass substrate for disc of roughness below 0.2nm of first type surface.Then, form the various layers of (film forming) magnetosphere etc. on glass substrate for disc, thereby make disk.

In addition, chemical enhanced operation is to carry out between the first grinding step and the second grinding step, but is not limited to this order.So long as carry out the second grinding step after the first grinding step, just can configure aptly chemical enhanced operation.For example, can be also the order (below, be called " process sequence 1 ") of the first grinding step, the second grinding step, chemical enhanced operation.But, in process sequence 1, owing to can't removing issuable concave-convex surface in chemical enhanced operation, therefore, the process sequence of the first grinding step, chemical enhanced operation, the second grinding step more preferably.

In addition, when making the magnetic recording media glass substrate, also can make the flatness of the glass blank that uses in processing identical in fact with the flatness of the magnetic recording media glass substrate that makes.Its reason is: in recent years, about to the desired flatness of magnetic recording media glass substrate, for example require its flatness at (in 10 μ m) below 10 μ m for the glass substrate of 2.5 inches, and the glass blank that the manufacture method of the glass blank by the second present embodiment is made can reach above-mentioned flatness at an easy rate.

At this, so-called " flatness of the glass blank that uses in processing is identical in fact with the flatness of the magnetic recording media glass substrate of manufacturing " refers to: with the desired flatness of magnetic recording media glass substrate during as benchmark (100%), the flatness of glass blank is below 105%.

In addition, in the situation that the flatness of the glass blank that uses in making processing is identical in fact with the flatness of the magnetic recording media glass substrate that makes, can omit the operation that grinding process etc. is implemented as one of fundamental purpose to improve flatness.

(manufacture method of magnetic recording media)

The manufacture method of the magnetic recording media of the second present embodiment is characterised in that, forms operation through the magnetic recording layer that forms magnetic recording layer on the magnetic recording media glass substrate of making in the manufacture method of the magnetic recording media glass substrate by the second present embodiment at least and makes magnetic recording media.

Magnetic recording media is called as disk, hard disk etc., and it is suitable for desk-top computer, server with the internal storage (fixed disk etc.) of computing machine, notebook computer, portable computer etc., with the internal storage of the potable recording regenerating unit of image and/or SoundRec regeneration, the record regenerator of vehicle audio etc.

Magnetic recording media for example can form following such structure; namely; on the first type surface of magnetic recording media glass substrate, from beginning to be laminated with at least successively adhesion layer, basalis, magnetosphere (magnetic recording layer), protective seam, lubricating layer near this main surface side.For example, the magnetic recording media glass substrate is imported in the film formation device of vacuum, and utilize direct current magnetron sputtering process to form successively (film forming) adhesion layer to magnetospheric various layers under argon gas atmosphere on the first type surface of magnetic recording media glass substrate.For example CrTi can be used as adhesion layer, for example CrRu can be used as basalis.After above-mentioned film forming, by for example CVD method (chemical vapour deposition technique) and use C ₂H ₄(ethene) gas and form (film forming) protective seam, and, carry out the nitrogen treatment that effects on surface imports nitrogen in same chamber, can form magnetic recording media thus.Then, apply for example PFPE (PFPE) by dip coating on protective seam, can form lubricating layer thus.

The size of magnetic recording media is not particularly limited, but, because the magnetic recording media glass substrate is to be made of the outstanding glass material of impact resistance, therefore, be preferably the high size below 2.5 inches or 2.5 inches of possibility of being convenient to carry and suffer external impact.

The＜the three present embodiment 〉

(the magnetic recording media glass substrate manufacture method of glass blank)

the manufacture method of the magnetic recording media glass substrate use glass blank of the 3rd present embodiment (below, sometimes referred to as " manufacture method of glass blank "), thereby comprise and utilize opposite and configuration and the identical in fact a pair of stamping forming die of temperature carry out direct punching press to fused glass block it is configured as the forming process of plate glass, this magnetic recording media glass substrate glass blank (below, sometimes referred to as " glass blank ") manufacture method be characterised in that, in forming process, utilize a pair of stamping forming die to continue the extrusion molten glass blocks, until the temperature that the temperature of fused glass block is reduced to after the strain point of the glass material that consists of plate glass+10 ℃ is following.

Because the drawing product of high temperature easily are out of shape, therefore, by utilizing a pair of stamping forming die to continue the extrusion molten glass blocks until the temperature of fused glass block is reduced to below said temperature, thereby thereby can prevent from being out of shape the glass blank of making desired shape.In this situation, preferably utilize a pair of stamping forming die to continue the extrusion molten glass blocks until the temperature of fused glass block is reduced to below the vitrification point of glass material.

In addition, preferably at the state of keeping fused glass block and a pair of stamping forming die close contact until the temperature of fused glass block is carried out annealing in process after being reduced to below the strain point of glass material.

Thereby by in the situation that carry out the warpage that annealing in process is eliminated (release) glass blank inside after drawing, be reduced to the temperature of strain point+10 ℃ when following when only continuing to carry out the temperature of punching press to fused glass block, exist in the inner residual danger that warpage is arranged of glass blank.But the state by keeping fused glass block and a pair of stamping forming die close contact can be controlled the cooling procedure of glass blank, thereby can eliminate the warpage of glass blank inside until the temperature of fused glass block is reduced to below strain point.

Thus, carry out even can access the glass blank that the annealing in process flatness also is difficult for variation.In addition, so-called " state of close contact " can be to utilize a pair of stamping forming die to continue the state of extrusion molten glass blocks, can be also that a pair of stamping forming die is not to apply the mode of power and the state of fused glass block close contact to fused glass block.

In addition, forming process can be also following such operation, namely, comprise for the first stamping procedure of the thickness of slab of determining plate glass and be used for improving the second stamping procedure of the flatness of plate glass, and, use a pair of stamping forming die to carry out continuously the first stamping procedure and the second stamping procedure.And then, preferably reach below 2mm according to the thickness of slab of plate glass and mode that flatness reaches (in 10 μ m) below 10 μ m forms operation.

In addition, the manufacture method of the glass blank of the 3rd present embodiment is suitable for making thinner and more smooth glass blank, and therefore, thickness of slab is more preferably below 1.5mm, further preferably below 1.2mm, further preferably below 1.0mm.

In addition, the manufacture method of the glass blank of the 3rd present embodiment can make up with each form of the manufacture method of the glass blank of the manufacture method of the glass blank of First embodiment or First embodiment.In addition, the magnetic recording media glass substrate of the 3rd present embodiment also can make up with each form of the manufacture method of the glass blank of the manufacture method of the glass blank of the second present embodiment or the second present embodiment with the manufacture method of glass blank.

(manufacture method of magnetic recording media glass substrate)

The manufacture method of the magnetic recording media glass substrate of the 3rd present embodiment is characterised in that, the manufacture method of the glass blank by the 3rd present embodiment is made glass blank, thereby and glass blank is processed made the magnetic recording media glass substrate.

In addition, in the manufacture method of the magnetic recording media glass substrate of the 3rd present embodiment, except the glass blank this point that the manufacture method of using the glass blank by the 3rd present embodiment is made, other are created conditions can be identical with the manufacture method of the magnetic recording media glass substrate of the manufacture method of the magnetic recording media glass substrate of above-mentioned First embodiment and/or the second present embodiment.

(manufacture method of magnetic recording media)

The manufacture method of the magnetic recording media of the 3rd present embodiment is characterised in that, the manufacture method of the magnetic recording media glass substrate by the 3rd present embodiment is made the magnetic recording media glass substrate, and forms operation through the magnetic recording layer that forms magnetic recording layer on the magnetic recording media glass substrate at least and make magnetic recording media.

In addition, in the manufacture method of the magnetic recording media of the 3rd present embodiment, except the magnetic recording media glass substrate this point that the manufacture method of using the magnetic recording media glass substrate by the 3rd present embodiment is made, other are created conditions can be identical with the manufacture method of the magnetic recording media of the manufacture method of the magnetic recording media of above-mentioned First embodiment and/or the second present embodiment.

Embodiment

＜First inventive embodiment 〉

Below, describe for embodiment, First being invented, still, the First invention is not limited in following embodiment.

" manufacturing of glass blank "

In each embodiment and comparative example, made continuously the magnetic recording media glass substrate manufacturing that is of a size of 2.5 inches more than hundreds of with glass blank (diameter: approximately 75mm, thickness: approximately 0.9mm).

(embodiment A 1)

Utilize Fig. 1～technique shown in Figure 9 to implement fused glass block and form operation, the first stamping procedure, the second stamping procedure and take out operation, thereby make glass blank.In addition, will be adjusted to 700dPas from the viscosity that glass flows exports 12 melten glass that flow out, the first stamping forming die 50 and the second stamping forming die 60 will be configured to vertical with the falling direction of fused glass block 24, distance of fall will be set as 150mm.

At this, the main physical parameters of the glass material that uses in the manufacturing of glass blank and composed as follows:

Vitrification point: 495 ℃

Yield point: 550 ℃

Strain point: 490 ℃

Form: be equivalent to glass and form 2 composition

In addition, the stamping forming die 50 that uses in the concrete implementation condition of the first stamping procedure and the second stamping procedure and drawing, 60 details are as follows.

The implementation condition of the-the first stamping procedure-

The temperature that is about to implement the drawing face 52A before the first stamping procedure is made as 500 ℃, the temperature that is about to implement the drawing face 62A before the first stamping procedure is made as 500 ℃, in the face of drawing face 52A before the first stamping procedure, temperature difference is made as 50 ℃ with being about to implement, and in the face of the drawing face 62A before the first stamping procedure, temperature difference is made as 50 ℃ with being about to implement.In addition, will be set as drawing face 52A to stamping forming die 50,60 driving contacts with fused glass block 24 with drawing face 62A simultaneously.In addition, the drawing time is made as 0.07 second.

In addition, the temperature of drawing face 52A, 62A is measured by being configured in from the thermopair of the dark 1mm of drawing face 52A, 62A position.This thermopair disposes one at the central part of drawing face 52A, 62A, and is to dispose respectively a thermopair along circumferencial direction in the position that is 0 °, 90 °, 180 °, 270 ° on the circumference of 30mm at the radius of decentering section.

The implementation condition of the-the second stamping procedure-

In the duration of adjusting the second stamping procedure, and the flatness of resulting glass blank is measured rear discovery, more than 2 seconds the time, the flatness of glass blank reaches 4 μ m when duration of the second stamping procedure.Therefore, the duration with the second stamping procedure is made as 2 seconds.The temperature (taking-up temperature) of the plate glass 26 when the second stamping procedure finishes is 495 ℃.Stamping pressure in the second stamping procedure process of enforcement is set as remains 0.5MPa.In addition, the temperature of plate glass 26 is to be assumed to be the value that the temperature of the thermocouple measurement of the central part by being configured in drawing face 52A, 62A is obtained.Thus, control the duration of the second stamping procedure as index take the flatness of glass blank, thereby obtained the outstanding glass blank of flatness.

-stamping forming die-

Stamping forming die 50 uses are made of cast iron and stamping forming die main body 52 is with guiding parts 54 the one-piece type stamping forming die that consists of integratedly.In addition, stamping forming die 60 similarly also uses one-piece type stamping forming die with stamping forming die 50.In addition, the whole face of drawing face 52A, 62A all forms tabular surface.

In addition, be provided with the runner of circulation chilled water in the one-piece type stamping forming die 50 that uses, 60 stamping forming die main body 52,62 inside, and dispose well heater at stamping forming die 50,60 outer circumferential side, thereby can control the temperature of drawing face 52A, 62A and the Temperature Distribution in face thereof.At this, the flow of chilled water and the heating condition of well heater are controlled so that the difference of the temperature of the drawing face 62A of the temperature of the drawing face 52A of stamping forming die 50 and stamping forming die 60 maintain all the time ± 10 ℃ with interior scope.

(embodiment A 2)

Be made as 490 ℃ except duration of further prolongation the second stamping procedure and with the taking-up temperature of plate glass, similarly make glass blank with embodiment A 1.

(embodiment A 3)

Except stamping forming die 50,60 uses stamping forming die main body 52,62 and guiding parts 54, opened in 64 minutes the divergence type stamping forming die of formation, similarly make glass blank with embodiment A 1.

(embodiment A 4)

Stamping pressure in time dependent ground reduction enforcement the second stamping procedure process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take the second stamping procedure, stamping pressure became 50% when the temperature of plate glass 26 reaches the temperature of yield point-25 ℃.

(embodiment A 5)

Stamping pressure in time dependent ground reduction enforcement the second stamping procedure process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take the second stamping procedure, stamping pressure became 50% when the temperature of plate glass 26 reaches the temperature of yield point+25 ℃.

(embodiment A 6)

Stamping pressure in time dependent ground reduction enforcement the second stamping procedure process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take the second stamping procedure, stamping pressure became 50% when the temperature of plate glass 26 reaches the temperature of yield point+40 ℃.

(embodiment A 7)

Stamping pressure in time dependent ground reduction enforcement the second stamping procedure process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take the second stamping procedure, stamping pressure became 50% when the temperature of plate glass 26 reaches the temperature of yield point-40 ℃.

(embodiment A 8)

Stamping pressure in time dependent ground reduction enforcement the second stamping procedure process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take the second stamping procedure, stamping pressure became 50% when the temperature of plate glass 26 reaches yield point.

(embodiment A 9)

Except the taking-up temperature with plate glass 26 is made as 485 ℃, and stamping forming die 50,60 uses outside the stamping forming die of divergence types, similarly makes glass blank with embodiment A 2.

(Comparative examples A 1)

Except the duration with the second stamping procedure is made as lower than 2 seconds and the taking-up temperature of plate glass is made as 520 ℃, similarly make glass blank with embodiment A 1.

(Comparative examples A 2)

Except omitting the second stamping procedure, similarly make glass blank with embodiment A 1.

(Comparative examples A 3)

Use the glass material identical with the material of use in embodiment A 1, and make glass blank by vertical directly impact style.Use the decompressor that possesses rotary table when making glass blank, wherein, be along its neighboring on this rotary table and equally spaced dispose 12 counterdies, and, when carrying out punching press, this rotary table rotates facing one direction in the mode that alternately repeats to move every 30 degree angles and stop.

In addition, when giving the numbering of P1～P12 along sense of rotation pair 12 counterdie stop positions corresponding with 12 counterdies on the neighboring that is configured in rotary table of rotary table, on the stamping surface that is in the counterdie on following counterdie stop position or the counterdie side dispose respectively following parts.

Counterdie stop position P1: molten glass supply apparatus

Counterdie stop position P2: patrix

Counterdie stop position P9: withdrawing device (vacuum absorption device)

In this decompressor, at counterdie stop position P1 place, supply with the melten glass of ormal weight to counterdie, at counterdie stop position P2 place, utilize upper die and lower die that the melten glass drawing is plate glass, at counterdie stop position P9 place, plate glass (glass blank) is taken out.In addition, implement soaking, refrigerating work procedure when counterdie moves from stop position P2 to stop position P9, utilize well heater to carry out preheating to counterdie from stop position P9 at counterdie when stop position P12 moves.

The stamping forming die 50 that uses in the material of upper die and lower die and the smoothness of drawing face, flatness and embodiment A 1,60 identical.In addition, the viscosity that is about to supply to the melten glass on the counterdie that is in counterdie stop position P1 place is adjusted to 500dPas.

The implementation condition of-stamping procedure-

In addition, the detailed implementation condition of stamping procedure is as follows.The temperature that is about to implement the drawing face of the patrix before stamping procedure is made as 380 ℃, the temperature that is about to implement the drawing face of the counterdie before stamping procedure is made as 480 ℃, in the face of drawing face of the patrix before stamping procedure, temperature difference is made as 30 ℃ with being about to implement, and in the face of drawing face of the counterdie before stamping procedure, temperature difference is made as 30 ℃ with being about to implement.In addition, from melten glass from ormal weight to counterdie that supplied with through after 2 seconds towards below drive patrix.

In addition, will contact to patrix and time (drawing time) till counterdie separates from patrix and melten glass on counterdie and be made as 0.3 second.In the situation that implement stamping procedure according to condition discussed above, the temperature (taking-up temperature) of the plate glass when stamping procedure finishes is 500 ℃.In addition, the temperature of the drawing face of upper die and lower die is measured by being configured in from the thermopair of the dark 5mm of drawing face position.This thermopair disposes one at the central part of drawing face, and is to dispose respectively a thermopair along circumferencial direction in the position that is 0 °, 90 °, 180 °, 270 ° on the circumference of 15mm at the radius of decentering section.

(Comparative examples A 4)

Except having extended the drawing time according to the mode of taking out temperature and become 495 ℃, similarly make glass blank with Comparative examples A 3.In addition, thereby lack practicality because speed of production is very slow, therefore, stop carrying out punching press after the glass blank of having made tens of left and right.

(Comparative examples A 5)

Except also disposing cooling using patrix on the stamping surface at counterdie stop position P3 place, decompressor uses the device identical with the decompressor of use in Comparative examples A 3.In addition, cooling with mold have with the stamping surface that is configured in counterdie stop position P2 place on drawing with the identical in fact structure of patrix.At this, implement according to the condition identical with Comparative examples A 3 at the stamping procedure of counterdie stop position P2 place's enforcement.

In addition, counterdie stop at counterdie stop position P3 place during in keep following state, that is what, make that integral body is preheated to 480 ℃ of left and right is cooling with patrix and to be configured in distance between plate glass on counterdie be cooling with patrix and the plate glass distance of exposure level soon.

(evaluation)

Flatness, crack and throughput rate for the glass blank of making in each embodiment and comparative example are estimated, and its result as shown in Table 1 to Table 3.In addition, in all embodiment by the direct stamped glass blank of level and Comparative examples A 1, A2, the temperature of implementing between the drawing face in the first stamping procedure and the second stamping procedure process is up to 550 ℃, in the Comparative examples A 3～A5 by vertical directly stamped glass blank, the temperature between the drawing face in enforcement stamping procedure process is in the scope of 450 ℃～500 ℃.

[table 1]

[table 2]

[table 3]

In addition, the evaluation method of the flatness shown in table 1～table 3, crack and throughput rate and evaluation criterion are as follows.

-flatness-

Flatness is to use three-dimensional measuring instrument (OMS of Co., Ltd. C system, high-precision three-dimensional shape measure system, MAP-3D) to measure, and has obtained the mean value of the flatness of 10 samples.

-crack-

In the situation that made continuously 1000 glass blanks, the quantity that produces the crack in resulting glass blank is added up, and obtained the generation rate in crack.In addition, the evaluation criterion of evaluation result shown in table 1～table 3 is as follows:

A: the generation rate in crack is 0%

B: the generation rate in crack is over 0% and below 1%

C: the generation rate in crack is over 1% and below 2%

D: the generation rate in crack is more than 2%

-throughput rate-

The quantity of the glass blank of having produced in time per unit when having obtained 1000 glass blanks of continuous manufacturing.In addition, the evaluation criterion of evaluation result shown in table 1～table 3 is as follows:

A: the quantity of per hour producing is more than 3420

B: the quantity of per hour producing is more than 3240 and be less than 3420

C: the quantity of per hour producing is more than 3060 and be less than 3240

D: the quantity of per hour producing is less than 3060

" manufacturing of magnetic recording media glass substrate and magnetic recording media "

＜Embodiment B 1 〉

Each glass blank of making in embodiment A 1～A9 is annealed, thereby reduce or remove warpage.Then, the part of the periphery that becomes the magnetic recording media glass substrate and center pit is implemented line processing.Form the groove of two concentric circles in the outside and inboard by this processing.Then, the finished part of ruling is carried out spot heating, utilize the difference that glass heat expands and produce the crack along the groove that line is processed to form, thereby Outboard Sections and the inboard part of outer concentric circle are removed.Thus, obtain the disk-shaped glass of positive toroidal.

Then, by chamfering etc., disk-shaped glass is implemented shape processing, and then carried out end surface grinding.Then, after the first type surface of disk-shaped glass having been implemented the first grinding, carried out glass immersion chemical enhanced in chemical enhanced liquid.After chemical enhanced, the glass after abundant cleaning implemented second grind.After the second grinding step, make the magnetic recording media glass substrate thereby again disk-shaped glass is cleaned.The external diameter of resulting magnetic recording media glass substrate is that 65mm, center bore are that 20mm, thickness are that the roughness of 0.8mm, first type surface is below 0.2nm.

In addition, when making the magnetic recording media glass substrate, omitted as described above the operation that grinding process etc. is implemented as one of fundamental purpose to improve flatness.But the flatness of the glass blank of the embodiment A 1～A8 that uses in processing is 4 μ m, and the flatness of the magnetic recording media glass substrate that the glass blank of use embodiment A 1～A8 is made is 4 μ m, and both flatnesses are almost identical.In addition, the flatness of the glass blank of the embodiment A 9 of using in processing is 3 μ m, and the flatness of the magnetic recording media glass substrate that the glass blank of use embodiment A 9 is made is 3 μ m, and both flatnesses are almost identical.In addition, similarly measured the flatness of magnetic recording media glass substrate with the measurement of the flatness of glass blank.

Then, use the magnetic recording media glass substrate that makes and form successively adhesion layer, basalis, magnetosphere, protective seam, lubricating layer on the first type surface of this magnetic recording media glass substrate, thereby obtaining magnetic recording media.

At first, the film formation device after use vacuum draw (vacuum drawing), and utilize direct current magnetron sputtering process to form successively (film forming) adhesion layer, basalis and magnetosphere in argon gas atmosphere.At this moment, adhesion layer is to use CrTi target (target) to form the thick noncrystalline CrTi layer of (film forming) 20nm.

Then, use cluster or static opposed type film formation device, and the 10nm that utilizes direct current magnetron sputtering process to form in argon gas atmosphere to be consisted of by noncrystalline CrRu thick layer as basalis.In addition, magnetosphere is to use FePt or CoPt target to form the thick noncrystalline FePt of (film forming) 200nm or CoPt layer under the film-forming temperature of 400 ℃.The magnetic recording media that film forming till magnetosphere has finished is transferred in heating furnace from film formation device, and annealed with the temperature of 650 ℃～700 ℃.

Then, form by the CVD method take ethene as unstrpped gas the protective seam that is consisted of by hydrogenated carbon (Hydrogenated carbon).Then, form lubricating layer by dip coating and use PFPE (PFPE).The film thickness of lubricating layer is 1nm.Obtain magnetic recording media by above manufacturing process.

Using the flatness of the magnetic recording media that the glass blank of embodiment A 1～A8 makes is 4 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.In addition, using the flatness of the magnetic recording media that the glass blank of embodiment A 9 makes is 3 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.In addition, similarly measure the flatness of magnetic recording media with the measurement of the flatness of glass blank.

＜comparative example B1 〉

The glass blank of making in usage comparison example A1 has been made the magnetic recording media glass substrate.In addition, when making the magnetic recording media glass substrate, except end surface grinding after and implement also to have implemented grinding allowance before the first grinding and be made as the grinding process of 50 μ m, similarly make the magnetic recording media glass substrate with Embodiment B 1.The external diameter of prepared magnetic recording media glass substrate is that 65mm, center bore are that 20mm, thickness are that 0.8mm, first type surface roughness are below 0.2nm.In addition, the flatness of the glass blank that uses in processing is 15 μ m, and the flatness of resulting magnetic recording media glass substrate is 4 μ m, and visible flatness is significantly improved.

Then, use the magnetic recording media glass substrate and the Embodiment B 1 that obtain similarly to make magnetic recording media.The flatness of resulting magnetic recording media is 4 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.

＜comparative example B2 〉

Except omitting grinding (lapping) operation, similarly make magnetic recording media glass substrate and magnetic recording media with comparative example B1.The flatness of the glass blank that uses in the flatness of resulting magnetic recording media glass substrate and magnetic recording media and processing is identical in fact.

＜comparative example B3 〉

The glass blank of making, similarly make magnetic recording media glass substrate and magnetic recording media with comparative example B1 in usage comparison example A5.The external diameter of resulting magnetic recording media glass substrate is that 65mm, center bore are that 20mm, thickness are that the roughness of 0.8mm, first type surface is below 0.2nm.In addition, the flatness of the glass blank that uses in processing is 15 μ m, and the flatness of the magnetic recording media glass substrate that makes is 4 μ m, and visible flatness is significantly improved.

Then, use the magnetic recording media glass substrate and the comparative example B1 that obtain similarly to make magnetic recording media.The flatness of resulting magnetic recording media is 4 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.

＜comparative example B4 〉

Except omitting grinding process, similarly make magnetic recording media glass substrate and magnetic recording media with comparative example B3.The flatness of the glass blank that uses in the flatness of resulting magnetic recording media glass substrate and magnetic recording media and processing is identical in fact.

The＜the second embodiments of the invention 〉

Below, for embodiment, second the present invention being described, still, second the present invention is not limited in following embodiment.

" manufacturing of glass blank "

In each embodiment and comparative example, made continuously the magnetic recording media glass substrate manufacturing that is of a size of 2.5 inches more than hundreds of with glass blank (diameter: approximately 75mm, thickness: approximately 0.9mm).

(embodiment A 1)

Utilize Figure 11～technique shown in Figure 19 to implement fused glass block and form operation, drawing operation (first step and second step) and take out operation, thereby make glass blank.In addition, will be adjusted to 700dPas from the viscosity that glass flows exports 112 melten glass that flow out, the first stamping forming die 150 and the second stamping forming die 160 will be configured to vertical with the falling direction of fused glass block 124, distance of fall will be made as 150mm.

At this, the main physical parameters of the glass material that uses in the manufacturing of glass blank and composed as follows:

Vitrification point: 495 ℃

Yield point: 550 ℃

Strain point: 490 ℃

Form: be equivalent to above-mentioned glass and form 2 composition

In addition, the stamping forming die 150 that uses in the concrete implementation condition of first step and second step and drawing, 160 details are as follows.

The implementation condition of-first step-

The temperature that is about to implement the drawing face 152A before first step is made as 500 ℃, the temperature that is about to implement the drawing face 162A before first step is made as 500 ℃, in the face of drawing face 152A before first step, temperature difference is made as 50 ℃ with being about to implement, and in the face of the drawing face 162A before first step, temperature difference is made as 50 ℃ with being about to implement.In addition, will be set as drawing face 152A to stamping forming die 150,160 driving contacts with fused glass block 124 with drawing face 162A simultaneously.In addition, the drawing time is made as 0.07 second.

In addition, the temperature of drawing face 152A, 162A is measured by being configured in from the thermopair of the dark 30mm of drawing face 152A, 162A position.This thermopair disposes one at the central part of drawing face 152A, 162A, and is to dispose respectively a thermopair along circumferencial direction in the position that is 0 °, 90 °, 180 °, 270 ° on the circumference of 1mm at the radius of decentering section.

The implementation condition of-second step-

The temperature of the plate glass 126 when second step is finished (taking-up temperature) is made as 495 ℃, is set as and maintains all the time 0.5MPa implementing stamping forming die main body 152,162 stamping pressure in the second step process.In addition, the temperature of plate glass 126 is to be assumed to be the value that the temperature of the thermocouple measurement of the central part by being configured in drawing face 152A, 162A is obtained.

-stamping forming die-

Stamping forming die 150 uses are made of cast iron and stamping forming die main body 152 is with guiding parts 154 the one-piece type stamping forming die that consists of integratedly.In addition, stamping forming die 160 similarly also uses one-piece type stamping forming die with stamping forming die 150.In addition, the whole face of drawing face 152A, 162A all forms tabular surface.

In addition, be provided with the runner of circulation chilled water in the stamping forming die 150 that uses, 160 stamping forming die main body 152,162 inside, and dispose well heater at stamping forming die 150,160 outer circumferential side, thereby can control the temperature of drawing face 152A, 162A and the Temperature Distribution in face thereof.

(embodiment A 2)

Be made as 490 ℃ except taking out temperature, similarly make glass blank with embodiment A 1.

(embodiment A 3)

Be made as 505 ℃ except taking out temperature, similarly make glass blank with embodiment A 1.

(embodiment A 4)

Stamping pressure in time dependent ground reduction enforcement second step process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take second step, stamping pressure became 50% when the temperature of plate glass 126 reaches the temperature of yield point-25 ℃.

(embodiment A 5)

Stamping pressure in time dependent ground reduction enforcement second step process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take second step, stamping pressure became 50% when the temperature of plate glass 126 reaches the temperature of yield point+25 ℃.

(embodiment A 6)

Stamping pressure in time dependent ground reduction enforcement second step process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take second step, stamping pressure became 50% when the temperature of plate glass 126 reaches the temperature of yield point-40 ℃.

(embodiment A 7)

Stamping pressure in time dependent ground reduction enforcement second step process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take second step, stamping pressure became 50% when the temperature of plate glass 126 reaches the temperature of yield point+40 ℃.

(embodiment A 8)

Stamping pressure in time dependent ground reduction enforcement second step process, similarly make glass blank with embodiment A 3.In addition, control in the following manner stamping pressure, that is, when soon stamping pressure was as benchmark (100%) after just having begun take second step, stamping pressure became 50% when the temperature of plate glass 126 reaches yield point.

(embodiment A 9)

Be made as 485 ℃ except taking out temperature, similarly make glass blank with embodiment A 2.

(Comparative examples A 1)

Except stamping forming die uses stamping forming die 300 shown in Figure 22, basically make glass blank according to the condition identical with embodiment A 1.But in the process of implementing second step, stamping pressure puts on stamping forming die 300 on the whole.

In addition, stamping forming die 300 shown in Figure 22 is made of cast iron, and has and will consist of the stamping forming die main body 152 and the integrated structure of guiding parts 154 of stamping forming die 150S shown in Figure 20.This stamping forming die 300 is cylindric and one end becomes drawing face 300A.In addition, be arranged with the protuberance 302 of ring-type along the peripheral edge portion of drawing face, this protuberance 302 has the function identical with guiding parts 154.

In addition, on the face of the opposition side of drawing face 300A, bar-like member 304 is installed, the other end of this bar-like member 304 is connected with not shown drive unit.In addition, the axial X that is installed to be with stamping forming die 300 of bar-like member 304 is coaxial shape.In addition, the stamping forming die 150S shown in Figure 20 that uses in the size of the smoothness of the drawing face 300A of stamping forming die 300 and flatness and drawing face 300A and protuberance 302 each several parts and each embodiment is identical in fact.

(Comparative examples A 2)

Except stamping forming die uses stamping forming die 310 shown in Figure 23, basically make glass blank according to the condition identical with embodiment A 1.But first step is that the thickness at plate glass 126 finishes when becoming the identical thickness of thickness with the glass blank of wanting to make, then, reduces stamping pressure and implements second step.In addition, in the process of implementing second step, stamping pressure puts on stamping forming die 310 on the whole.

In addition, stamping forming die 310 shown in Figure 23 is made of cast iron, and has the structure of the stamping forming die main body 152 that is equivalent to consist of stamping forming die 150S shown in Figure 20.This stamping forming die 310 is cylindric and one end becomes drawing face 310A.In addition, on the face of the opposition side of drawing face 310A, bar-like member 312 is installed, the other end of this bar-like member 312 is connected with not shown drive unit.In addition, the axial X that is installed to be with stamping forming die 310 of bar-like member 312 is coaxial shape.

(evaluation)

Flatness, thickness deviation and crack for the glass blank of making in each embodiment and comparative example are estimated, and its result is as shown in table 4 and table 5.In addition, in embodiment and comparative example, the temperature of implementing two drawing faces in first step and second step process is all almost identical, and is up to 505 ℃.

[table 4]

[table 5]

In addition, the evaluation method in the flatness shown in table 4 and table 5, thickness deviation and crack and evaluation criterion are as follows.

-flatness-

Flatness is to use three-dimensional measuring instrument (OMS of Co., Ltd. C system, high-precision three-dimensional shape measure system, MAP-3D) to measure, and has obtained the mean value of the flatness of 10 samples.

-thickness deviation-

Thickness deviation is to utilize milscale that the central point of the glass blank that makes and radius are measured for the thickness that is in 0 °, 90 °, 180 °, 270 ° position along circumferencial direction on the position of 30mm, and obtains the standard deviation of above-mentioned five positions.Then, obtain the mean value of the standard deviation of 10 samples.

-crack-

In the situation that made continuously 1000 glass blanks, the quantity that produces the crack in the glass blank that obtains is added up and is obtained the generation rate in crack.In addition, the evaluation criterion of the evaluation result shown in table 4 and table 5 is as follows:

A: the generation rate in crack is 0%

B: the generation rate in crack is over 0% and below 1%

C: the generation rate in crack is over 1% and below 2%

D: the generation rate in crack is more than 3%

" manufacturing of magnetic recording media glass substrate and magnetic recording media "

＜Embodiment B 1 〉

Each glass blank of making in embodiment A 1～A9 is annealed, thereby reduce or remove warpage.Then, the part of the periphery that becomes the magnetic recording media glass substrate and center pit is implemented line processing.Form the groove of two concentric circles in the outside and inboard by this processing.Then, the finished part of ruling is carried out spot heating, and utilize the difference that glass heat expands and produce the crack along the groove that line is processed to form, thereby Outboard Sections and the inboard part of outer concentric circle are removed.Thus, obtain the disk-shaped glass of positive toroidal.

Then, by chamfering etc., disk-shaped glass is implemented shape processing, and then disk-shaped glass is implemented end surface grinding.Then, after the first type surface of disk-shaped glass having been implemented the first grinding, carry out glass immersion chemical enhanced in chemical enhanced liquid.After chemical enhanced, the glass after abundant cleaning implemented second grind.After the second grinding step, make the magnetic recording media glass substrate thereby again disk-shaped glass is cleaned.The external diameter of prepared magnetic recording media glass substrate is that 65mm, center bore are that 20mm, thickness are that the roughness of 0.8mm, first type surface is below 0.2nm.

In addition, when making the magnetic recording media glass substrate, omitted as described above the operation that grinding process etc. is implemented as one of fundamental purpose to improve flatness.But the flatness of the glass blank of the embodiment A 1～A8 that uses in processing is 4 μ m, and the flatness of the magnetic recording media glass substrate that the glass blank of use embodiment A 1～A8 is made is 4 μ m, and both flatnesses are almost identical.In addition, the flatness of the glass blank of the embodiment A 9 of using in processing is 3 μ m, and the flatness of the magnetic recording media glass substrate that the glass blank of use embodiment A 9 is made is 3 μ m, and both flatnesses are almost identical.In addition, similarly measure the flatness of magnetic recording media glass substrate with the measurement of the flatness of glass blank.

Then, use the magnetic recording media glass substrate that makes, and form successively adhesion layer, basalis, magnetosphere, protective seam, lubricating layer on the first type surface of this magnetic recording media glass substrate, thereby obtain magnetic recording media.

At first, the film formation device after the use vacuum draw, and utilize direct current magnetron sputtering process to form successively (film forming) adhesion layer, basalis and magnetosphere in argon gas atmosphere.At this moment, adhesion layer is to use the CrTi target to form (film forming) to be the thick noncrystalline CrTi layer of 20nm.

Then, use cluster or static opposed type film formation device, and the 10nm that utilizes direct current magnetron sputtering process to form in argon gas atmosphere to be consisted of by noncrystalline CrRu thick layer as basalis.In addition, magnetosphere is to use FePt or CoPt target to form (film forming) under the film-forming temperature of 400 ℃ to be 200nm thick noncrystalline FePt or CoPt layer.The magnetic recording media that film forming till magnetosphere has finished is transferred in heating furnace from film formation device, and annealed with the temperature of 650 ℃～700 ℃.

Then, form by the CVD method take ethene as unstrpped gas the protective seam that is consisted of by hydrogenated carbon (Hydrogenated carbon).Then, by dip coating and utilize PFPE (PFPE) to form lubricating layer, the film thickness of lubricating layer is 1nm.Obtained magnetic recording media by above manufacturing process.

Using the flatness of the magnetic recording media that the glass blank of embodiment A 1～A8 makes is 4 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.In addition, using the flatness of the magnetic recording media that the glass blank of embodiment A 9 makes is 3 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.In addition, similarly measure the flatness of magnetic recording media with the measurement of the flatness of glass blank.

＜comparative example B1 〉

The glass blank of making in usage comparison example A1 has been made the magnetic recording media glass substrate.In addition, when making the magnetic recording media glass substrate, except end surface grinding after and implement also to have implemented grinding allowance before the first grinding and be made as the grinding process of 50 μ m, similarly make the magnetic recording media glass substrate with Embodiment B 1.The external diameter of resulting magnetic recording media glass substrate is that 65mm, center bore are that 20mm, thickness are that 0.8mm, first type surface roughness are below 0.2nm.In addition, the flatness of the glass blank that uses in processing is 15 μ m, and the flatness of the magnetic recording media glass substrate that makes is 4 μ m, and visible flatness is significantly improved.

Then, use the magnetic recording media glass substrate and the Embodiment B 1 that obtain similarly to make magnetic recording media.The flatness of resulting magnetic recording media is 4 μ m, and the flatness of the magnetic recording media glass substrate that uses in the manufacturing of itself and magnetic recording media is almost identical.

＜comparative example B2 〉

Except omitting grinding process, similarly make magnetic recording media glass substrate and magnetic recording media with comparative example B1.In the flatness of resulting magnetic recording media glass substrate and magnetic recording media and processing, the flatness of the glass blank that uses is identical in fact.

Claims (45)

1. the manufacture method of a magnetic recording media glass substrate use glass blank, is characterized in that,

At least make magnetic recording media glass substrate glass blank through the first stamping procedure, the second stamping procedure and taking-up operation,

In described the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as described fused glass block tabular, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

In described the second stamping procedure, utilize described the first stamping forming die and described the second stamping forming die to continue the plate glass that forms between described the first stamping forming die and described the second stamping forming die is carried out punching press,

In described taking-up operation, after having passed through described the second stamping procedure, described the first stamping forming die is separated with described the second stamping forming die, thereby the described plate glass that will be clamped between described the first stamping forming die and described the second stamping forming die take out

Use in the manufacture method of glass blank at described magnetic recording media glass substrate, at least in during described the first stamping procedure of enforcement and described the second stamping procedure, make the temperature of drawing face of described the first stamping forming die identical in fact with the temperature of the drawing face of described the second stamping forming die

In described the first stamping procedure, roughly simultaneously with after described fused glass block contacts described fused glass block is carried out punching press at the drawing face of the drawing face that makes described the first stamping forming die and described the second stamping forming die,

Duration to described the second stamping procedure is controlled, so that described magnetic recording media glass substrate reaches below 10 μ m with the flatness of glass blank.

2. magnetic recording media glass substrate as claimed in claim 1 with the manufacture method of glass blank, is characterized in that,

Duration to described the second stamping procedure is selected, so that the temperature of the described plate glass of described the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ at least.

3. magnetic recording media glass substrate as claimed in claim 1 or 2 with the manufacture method of glass blank, is characterized in that,

Described magnetic recording media glass substrate comprises also that with the manufacture method of glass blank thereby the leading section with molten glass flow cuts off the fused glass block formation operation that forms described fused glass block, wherein, described molten glass flow is to make melten glass hang down and flow out continuously and form towards the lower side of vertical direction from glass flows outlet.

4. magnetic recording media glass substrate as claimed in claim 3 with the manufacture method of glass blank, is characterized in that, the viscosity of described melten glass is in the scope of 500dPas～1050dPas.

5. magnetic recording media glass substrate as described in any one in claim 1～4 with the manufacture method of glass blank, is characterized in that,

Described the first stamping forming die and described the second stamping forming die arranged opposite on the direction vertical with the falling direction of described fused glass block.

6. magnetic recording media glass substrate as described in any one in claim 1～5 with the manufacture method of glass blank, is characterized in that,

Be about to implement the temperature of drawing face of described the first stamping forming die before described the first stamping procedure and described the second stamping forming die below the temperature of the strain point of the glass material that consists of described fused glass block+10 ℃.

7. magnetic recording media glass substrate as described in any one in claim 1～6 with the manufacture method of glass blank, is characterized in that, makes the stamping pressure in described the second stamping procedure be time dependent ground reduction.

8. magnetic recording media glass substrate as claimed in claim 7 with the manufacture method of glass blank, is characterized in that,

When being reduced in the scope of the yield point of the glass material that consists of described plate glass ± 30 ℃, the temperature that is clamped in the described plate glass between described the first stamping forming die and described the second stamping forming die reduces described stamping pressure.

9. magnetic recording media glass substrate as described in any one in claim 1～8 with the manufacture method of glass blank, is characterized in that,

In the process of implementing described the second stamping procedure, the drawing face that makes a face of described plate glass and described the first stamping forming die is seamless unoccupied place close contact all the time, and the drawing face that makes another face of described plate glass and described the second stamping forming die seamless unoccupied place close contact all the time.

10. magnetic recording media glass substrate as described in any one in claim 1～9 with the manufacture method of glass blank, is characterized in that,

Duration to described the second stamping procedure is controlled, so that described magnetic recording media glass substrate reaches below 4 μ m with the flatness of glass blank.

11. magnetic recording media glass substrate as described in any one in claim 1～10 manufacture method of glass blank is characterized in that,

At least the zone that contacts with described plate glass of the drawing face of described the first stamping forming die and described the second stamping forming die is the face of general planar.

12. the manufacture method of a magnetic recording media glass substrate is characterized in that,

At least through the first stamping procedure, the second stamping procedure and take out operation make the magnetic recording media glass substrate with glass blank after, at least make the magnetic recording media glass substrate through grinding step that described magnetic recording media glass substrate is ground with the first type surface of glass blank

In described the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as described fused glass block tabular, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

In described the second stamping procedure, utilize described the first stamping forming die and described the second stamping forming die to continue the plate glass that forms between described the first stamping forming die and described the second stamping forming die is carried out punching press,

In described taking-up operation, after having passed through described the second stamping procedure, described the first stamping forming die is separated with described the second stamping forming die, thereby the described plate glass that will be clamped between described the first stamping forming die and described the second stamping forming die take out

In the manufacture method of described magnetic recording media glass substrate, at least in during described the first stamping procedure of enforcement and described the second stamping procedure, make the temperature of drawing face of described the first stamping forming die identical in fact with the temperature of the drawing face of described the second stamping forming die

In described the first stamping procedure, roughly simultaneously with after described fused glass block contacts described fused glass block is carried out punching press at the drawing face of the drawing face that makes described the first stamping forming die and described the second stamping forming die,

Duration to described the second stamping procedure is controlled, so that described magnetic recording media glass substrate reaches below 10 μ m with the flatness of glass blank.

13. the manufacture method of magnetic recording media glass substrate as claimed in claim 12 is characterized in that,

Duration to described the second stamping procedure is selected, so that the temperature of the described plate glass of described the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ at least.

14. the manufacture method of magnetic recording media glass substrate as described in claim 12 or 13 is characterized in that,

Described magnetic recording media glass substrate is identical in fact with the flatness of described magnetic recording media glass substrate with the flatness of glass blank.

15. the manufacture method of a magnetic recording media is characterized in that,

At least through the first stamping procedure, the second stamping procedure and take out operation make the magnetic recording media glass substrate with glass blank after, at least through described magnetic recording media glass substrate is made the magnetic recording media glass substrate with the grinding step that the first type surface of glass blank grinds, and then form operation and make magnetic recording media through the magnetic recording layer that forms magnetic recording layer on described magnetic recording media glass substrate at least

In described the first stamping procedure, thereby utilizing the first stamping forming die and the second stamping forming die to carry out punching press to the fused glass block in falling is configured as described fused glass block tabular, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

In described the second stamping procedure, utilize described the first stamping forming die and described the second stamping forming die to continue the plate glass that forms between described the first stamping forming die and described the second stamping forming die is carried out punching press,

In described taking-up operation, after having passed through described the second stamping procedure, described the first stamping forming die is separated with described the second stamping forming die, thereby the described plate glass that will be clamped between described the first stamping forming die and described the second stamping forming die take out

In the manufacture method of described magnetic recording media, at least in during described the first stamping procedure of enforcement and described the second stamping procedure, make the temperature of drawing face of described the first stamping forming die identical in fact with the temperature of the drawing face of described the second stamping forming die

In described the first stamping procedure, roughly simultaneously with after described fused glass block contacts described fused glass block is carried out punching press at the drawing face of the drawing face that makes described the first stamping forming die and described the second stamping forming die,

Duration to described the second stamping procedure is controlled, so that described magnetic recording media glass substrate reaches below 10 μ m with the flatness of glass blank.

16. the manufacture method of magnetic recording media as claimed in claim 15 is characterized in that,

Duration to described the second stamping procedure is selected, so that the temperature of the described plate glass of described the second stamping procedure when finishing becomes below the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ at least.

17. the manufacture method as claim 15 or 16 described magnetic recording medias is characterized in that,

Described magnetic recording media glass substrate is identical in fact with the flatness of described magnetic recording media glass substrate with the flatness of glass blank.

18. the magnetic recording media glass substrate manufacture method of glass blank is characterized in that,

At least through utilizing the first stamping forming die and the second stamping forming die to make magnetic recording media glass substrate glass blank to the drawing operation that the fused glass block in falling carries out drawing, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

At least described the first stamping forming die is provided with stamping forming die main body and guiding parts at least,

Described stamping forming die main body is provided with drawing face,

Described guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and described second stamping forming die side configuration opposite with described drawing face promotes, with opposite with described drawing face and the part of described the second stamping forming die configuration contacts, thus the distance between the drawing face of described the first stamping forming die and described the second stamping forming die is remained roughly fixing distance

Described drawing operation comprises first step and second step,

In described first step, make described the first stamping forming die and described the second stamping forming die mutually near until the guiding parts of described the first stamping forming die contact with described the second stamping forming die, thus described fused glass block is configured as plate glass

In described second step, under the guiding parts of described the first stamping forming die and state that described the second stamping forming die contacts, utilize the stamping forming die main body of described the first stamping forming die and described the second stamping forming die further to continue described plate glass is carried out punching press.

19. the magnetic recording media glass substrate as claimed in claim 18 manufacture method of glass blank is characterized in that,

Described the first stamping forming die and described the second stamping forming die are provided with respectively stamping forming die main body and guiding parts at least,

Described stamping forming die main body is provided with drawing face,

Described guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and another stamping forming die side configuration opposite with described drawing face promotes, with opposite with described drawing face and the part of another stamping forming die configuration contacts, thus the distance between the drawing face of described the first stamping forming die and described the second stamping forming die is remained roughly fixing distance

Described first step is implemented by following manner, aforesaid way refers to: make described the first stamping forming die and described the second stamping forming die mutually close, until the guiding parts of described the first stamping forming die contacts with the guiding parts of described the second stamping forming die

Described second step is implemented by following manner, aforesaid way refers to: under the guiding parts of described the first stamping forming die and state that the guiding parts of described the second stamping forming die contacts, utilize the stamping forming die main body of described the first stamping forming die and the stamping forming die main body of described the second stamping forming die further to continue described plate glass is carried out punching press.

20. magnetic recording media glass substrate as described in claim 18 or 19 manufacture method of glass blank is characterized in that,

Described magnetic recording media glass substrate comprises also that with the manufacture method of glass blank thereby the leading section with molten glass flow cuts off the fused glass block formation operation that forms described fused glass block, wherein, described molten glass flow is to make melten glass hang down and flow out continuously and form towards the lower side of vertical direction from glass flows outlet.

21. the magnetic recording media glass substrate as claimed in claim 20 manufacture method of glass blank is characterized in that the viscosity of described melten glass is in the scope of 500dPas～1050dPas.

22. magnetic recording media glass substrate as described in any one in claim 18～21 manufacture method of glass blank is characterized in that,

Described the first stamping forming die and described the second stamping forming die arranged opposite on the direction vertical with the falling direction of described fused glass block.

23. magnetic recording media glass substrate as described in any one in claim 18～22 manufacture method of glass blank is characterized in that,

Duration to described second step is controlled, so that described magnetic recording media glass substrate reaches below 10 μ m with the flatness of glass blank.

24. magnetic recording media glass substrate as described in any one in claim 18～23 manufacture method of glass blank is characterized in that,

Duration to described second step is selected, so that the temperature of the described plate glass of described second step when finishing becomes below the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ at least.

25. magnetic recording media glass substrate as described in any one in claim 18～24 manufacture method of glass blank is characterized in that,

Be about to implement the absolute value of difference of temperature of stamping forming die of the temperature of drawing face of described the first stamping forming die before described first step and described the second stamping forming die in the scope of 0 ℃～10 ℃.

26. magnetic recording media glass substrate as described in any one in claim 18～25 manufacture method of glass blank is characterized in that,

Be about to implement the absolute value of temperature difference in the face of drawing face of described the first stamping forming die before described first step and described the second stamping forming die in the scope of 0 ℃～100 ℃.

27. magnetic recording media glass substrate as described in any one in claim 18～26 manufacture method of glass blank is characterized in that,

At least implement described drawing operation during in, make the temperature of drawing face of described the first stamping forming die identical in fact with the temperature of the drawing face of described the second stamping forming die,

And, roughly simultaneously with after described fused glass block contacts described fused glass block is carried out drawing at the drawing face of the drawing face that makes described the first stamping forming die and described the second stamping forming die.

28. magnetic recording media glass substrate as described in any one in claim 18～27 manufacture method of glass blank is characterized in that,

Continue to carry out described second step until the temperature of described plate glass to become at least the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ following.

29. magnetic recording media glass substrate as described in any one in claim 18～28 is characterized in that with the manufacture method of glass blank, makes the stamping pressure in described second step be time dependent ground reduction.

30. the magnetic recording media glass substrate as claimed in claim 29 manufacture method of glass blank is characterized in that,

When being reduced in the scope of the yield point of the glass material that consists of described plate glass ± 30 ℃, the temperature that is clamped in the described plate glass between described the first stamping forming die and described the second stamping forming die reduces described stamping pressure.

31. magnetic recording media glass substrate as described in any one in claim 18～30 manufacture method of glass blank is characterized in that, described magnetic recording media glass substrate uses the flatness of glass blank below 10 μ m.

32. magnetic recording media glass substrate as described in any one in claim 18～31 manufacture method of glass blank is characterized in that, described magnetic recording media glass substrate uses the flatness of glass blank below 4 μ m.

33. magnetic recording media glass substrate as described in any one in claim 18～32 manufacture method of glass blank is characterized in that,

At least the zone that contacts with described plate glass of the drawing face of described the first stamping forming die and described the second stamping forming die is the face of general planar.

34. magnetic recording media glass substrate as described in any one in claim 18～33 manufacture method of glass blank is characterized in that,

Described the first stamping forming die and described the second stamping forming die also are provided with respectively the first push mechanism and the second push mechanism,

Described the first push mechanism along the direction vertical with described drawing face towards with described drawing face opposite and the configuration another stamping forming die side promote simultaneously described stamping forming die main body and described guiding parts,

After making described guiding parts by described the first push mechanism and a part with opposite another stamping forming die that configures of described drawing face contact, described the second push mechanism along the direction vertical with described drawing face towards opposite with described drawing face and another stamping forming die side configuration promotes described stamping forming die main body.

35. the manufacture method of a magnetic recording media glass substrate is characterized in that,

Make through the drawing operation at least the magnetic recording media glass substrate with glass blank after, make the magnetic recording media glass substrate through grinding step that described magnetic recording media glass substrate is ground with the first type surface of glass blank at least,

In described drawing operation, utilize the first stamping forming die and the second stamping forming die to carry out drawing to the fused glass block in falling, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

At least described the first stamping forming die is provided with stamping forming die main body and guiding parts at least,

Described stamping forming die main body is provided with drawing face,

Described guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and described second stamping forming die side configuration opposite with described drawing face promotes, with opposite with described drawing face and the part of described the second stamping forming die configuration contacts, thus the distance between the drawing face of described the first stamping forming die and described the second stamping forming die is remained roughly fixing distance

Described drawing operation comprises first step and second step,

In described first step, make described the first stamping forming die and described the second stamping forming die mutually near until the guiding parts of described the first stamping forming die contact with described the second stamping forming die, thus described fused glass block is configured as plate glass

In described second step, under the guiding parts of described the first stamping forming die and state that described the second stamping forming die contacts, utilize the stamping forming die main body of described the first stamping forming die and described the second stamping forming die further to continue described plate glass is carried out punching press.

36. the manufacture method of magnetic recording media glass substrate as claimed in claim 35 is characterized in that,

Described magnetic recording media glass substrate is identical in fact with the flatness of described magnetic recording media glass substrate with the flatness of glass blank.

37. the manufacture method of a magnetic recording media is characterized in that,

Make through the drawing operation at least the magnetic recording media glass substrate with glass blank after, at least through described magnetic recording media glass substrate is made the magnetic recording media glass substrate with the grinding step that the first type surface of glass blank grinds, and then form operation and make magnetic recording media through the magnetic recording layer that forms magnetic recording layer on described magnetic recording media glass substrate at least

In described drawing operation, utilize the first stamping forming die and the second stamping forming die to carry out drawing to the fused glass block in falling, wherein, described the first stamping forming die and described the second stamping forming die arranged opposite on the direction that the falling direction with described fused glass block intersects

At least described the first stamping forming die is provided with stamping forming die main body and guiding parts at least,

Described stamping forming die main body is provided with drawing face,

Described guiding parts has following function at least, above-mentioned functions refers to: when drawing by when and described second stamping forming die side configuration opposite with described drawing face promotes, with opposite with described drawing face and the part of described the second stamping forming die configuration contacts, thus the distance between the drawing face of described the first stamping forming die and described the second stamping forming die is remained roughly fixing distance

Described drawing operation comprises first step and second step,

In described first step, make described the first stamping forming die and described the second stamping forming die mutually near until the guiding parts of described the first stamping forming die contact with described the second stamping forming die, thus described fused glass block is configured as plate glass

In described second step, under the guiding parts of described the first stamping forming die and state that described the second stamping forming die contacts, utilize the stamping forming die main body of described the first stamping forming die and described the second stamping forming die further to continue described plate glass is carried out punching press.

38. the manufacture method of magnetic recording media as claimed in claim 37 is characterized in that,

Described magnetic recording media glass substrate is identical in fact with the flatness of described magnetic recording media glass substrate with the flatness of glass blank.

39. the magnetic recording media glass substrate manufacturing installation of glass blank is characterized in that possessing at least:

Melten glass flows out pipe, and it is provided with the flow export that molten glass flow is hung down towards the vertical direction lower side,

A pair of shear-blade, it is configured in the both sides of the direction that hangs down of described molten glass flow in opposed mode on the direction substantially vertical with the direction that hangs down of the molten glass flow that flows out the pipe outflow from described melten glass, and, leading section by inserting from the both sides of described molten glass flow with described molten glass flow cuts off, thereby the formation fused glass block, and

The first stamping forming die and the second stamping forming die, it is configured in the both sides of the falling direction of described fused glass block in opposed mode on the direction substantially vertical with the falling direction of the described fused glass block that falls towards the vertical direction lower side, and, thereby be plate glass by clamping described fused glass block with described fused glass block drawing from both sides

At least described the first stamping forming die possesses at least:

The stamping forming die main body, it is provided with drawing face,

Guiding parts, it has following function at least, above-mentioned functions refers to: when drawing by when and described second stamping forming die side configuration opposite with described drawing face promotes, with opposite with described drawing face and the part of described the second stamping forming die configuration contacts, thus the distance between the drawing face of described the first stamping forming die and described the second stamping forming die is remained roughly fixing distance

The first push mechanism, its along the direction vertical with described drawing face towards with described drawing face opposite and the configuration described the second stamping forming die side promote simultaneously described stamping forming die main body and described guiding parts, and

The second push mechanism, its after making described guiding parts by described the first push mechanism and a part with opposite described the second stamping forming die that configures of described drawing face contact, along the direction vertical with described drawing face towards opposite with described drawing face and described the second stamping forming die side configuration promotes described stamping forming die main body.

40. the magnetic recording media glass substrate manufacture method of glass blank, thereby it comprises that using a pair of stamping forming die to carry out direct punching press to fused glass block is configured as fused glass block the forming process of plate glass, wherein, a pair of described stamping forming die opposite and the configuration and temperature identical in fact

Described magnetic recording media glass substrate is characterised in that with the manufacture method of glass blank,

In described forming process, utilize a pair of described stamping forming die to continue the described fused glass block of extruding, until that the temperature of described fused glass block becomes the temperature of the strain point of the glass material that consists of described plate glass+10 ℃ is following.

41. the magnetic recording media glass substrate as claimed in claim 40 manufacture method of glass blank is characterized in that,

At the state of keeping described fused glass block and a pair of described stamping forming die close contact until after the temperature of described fused glass block becomes below the strain point of described glass material, carry out annealing in process.

42. magnetic recording media glass substrate as described in claim 40 or 41 manufacture method of glass blank is characterized in that,

Described forming process comprises for the first stamping procedure of the thickness of slab of determining described plate glass and is used for improving the second stamping procedure of the flatness of described plate glass,

And, use a pair of described stamping forming die to carry out continuously described the first stamping procedure and described the second stamping procedure.

43. magnetic recording media glass substrate as described in any one in claim 40～42 manufacture method of glass blank is characterized in that,

The mode that thickness reaches below 2mm and flatness reaches below 10 μ m according to described plate glass is implemented described forming process.

44. the manufacture method of a magnetic recording media glass substrate is characterized in that,

Make magnetic recording media glass substrate glass blank by the described manufacture method of any one in claim 40～43, thereby and described magnetic recording media glass substrate is processed with glass blank made the magnetic recording media glass substrate.

45. the manufacture method of a magnetic recording media is characterized in that,

Make described magnetic recording media glass substrate by the described manufacture method of claim 44, and make magnetic recording media through the magnetic recording layer formation operation that forms magnetic recording layer on described magnetic recording media glass substrate at least.

Images