JP2006315873A - Methods for manufacturing glass blank and glass substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a flat ring-shaped glass blank, wherein drilling of its center is not required. <P>SOLUTION: In the method, the flat ring-shaped glass blank is manufactured using a first die and an extrusion member, wherein the first die has an annular passage through which molten glass passes and a flat first molding surface, and the extrusion member slides into the annular passage. The extrusion member sliding along the annular passage cuts and extrudes the molten glass present inside the annular passage, and the extruded annular glass gob is molded on the first molding surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a glass blank manufacturing method for manufacturing glass blanks used for glass substrates for information recording media and the like from molten glass.

  In general, glass blanks are made by sending molten glass from a cylindrical nozzle, and when the molten glass reaches a certain amount, the molten glass is cut with a cutting blade (shear) to produce a glass gob, and this glass gob is press-molded with a die. It is made by doing.

  In the conventional method for dividing molten glass, the cutting blade (shear) is placed further forward than the outlet portion of the cylindrical nozzle, that is, the nozzle opening, so that the shape of the glass gob is broken by cutting with the cutting blade (shear). However, there is a problem that only a stubby-shaped simple lump can be obtained and a complicated shape such as a donut shape cannot be obtained, or a cut trace remains in the obtained glass gob.

  By the way, a hard disk using a glass substrate has attracted a great deal of attention as a high-density information recording medium. A hard disk using a glass substrate is obtained by sequentially laminating a base layer, a recording layer, a protective layer, and the like on the surface of a flat ring-shaped glass substrate. Since the hard disk is rotationally driven by a motor, the central hole of the flat ring-shaped glass substrate is used as the center of the rotational drive.

  Conventionally, a flat ring-shaped glass substrate having a central hole is manufactured, for example, by the following method (see, for example, Patent Documents 1 to 3).

That is, the molten glass is fed from a nozzle, and when the molten glass becomes a certain amount, the molten glass is cut with a cutting blade (shear) to produce a glass gob. And this glass gob is press-molded with a metal mold | die, and disk-shaped glass blanks are produced. After that, by drilling the central portion of the disk-shaped glass blanks, a drilling process was performed to open a hole in the central portion. Such a drilling process cannot be performed on a large number of glass blanks at the same time, so it is difficult to increase the productivity and the cost is very high.
JP 2003-55001 A JP 2003-54965 A JP 2003-63831 A

  Therefore, the technical problem to be solved by the present invention is to provide a method for producing flat ring-shaped glass blanks that does not require drilling the central portion.

Means and actions / effects for solving the problem

  In order to solve the above technical problem, a flat plate ring using an annular passage through which molten glass flows and a first mold having a flat first molding surface, and an extrusion member that slides in the annular passage. The glass glass blanks are manufactured by cutting the extruded glass in the annular passage and extruding the extruded annular glass gob by sliding the extruded member along the annular passage. The manufacturing method of the glass blank characterized by shape | molding on a shaping | molding surface is provided.

  According to the above method, the molten glass is cut into an annular shape by sliding of the extruded member and extruded, and the extruded annular glass gob is molded on the flat first molding surface, thereby forming a flat first. A generally flat ring-shaped glass blank having the molding surface transferred can be produced. Therefore, at least one surface of the glass blank becomes a flat molding surface, and the time and cost of post-processing can be reduced.

  The flat second molding surface of the second mold is placed opposite to the first molding surface, and the extruded annular glass gob is pressed between the first molding surface and the second molding surface to make it flat. A flat plate-shaped glass blank having a surface on which the first molding surface is transferred and a surface on which the flat second molding surface is transferred can be produced. Therefore, the upper and lower surfaces of the glass blanks become flat molding surfaces, and the post-processing time and cost can be reduced.

  When considering the use for an information recording medium, since the central hole is used as a rotational drive reference hole when it is rotationally driven by a motor, it is necessary to accurately dimension the central hole. Therefore, the first inner diameter restricting portion and the second inner diameter restricting portion are provided in the center of the first die and the second die, respectively, and the annular glass gob that is unevenly supplied to the inner diameter side is press-molded, By restricting the inner diameter portion of the annular glass gob by the first inner diameter regulating portion and the second inner diameter regulating portions, it is possible to produce flat plate-shaped glass blanks having a precisely sized central hole diameter.

  When molding with the second mold, the glass gob expands toward the inner diameter regulating portion and the outer diameter portion while being crushed. The upper end of the inner diameter restricting portion is above the upper surface of the annular glass gob so that the molten glass enters inside from the inner diameter restricting portion when the second die and the first die are fitted and no burr is generated in the center hole corresponding portion. In addition, it is preferable that the inner diameter regulating portion moves downward when press molding with the second die.

  In order to flatly spread the annular glass gob extruded on the first molding surface, the first mold is driven to rotate, and the extruded annular glass gob is molded on the first molding surface by centrifugal force. A generally flat ring-shaped glass blank having a flat first molding surface transferred thereon can be produced. Therefore, at least one surface of the glass blank becomes a flat molding surface, and the time and cost of post-processing can be reduced.

  By rotating the first mold whose first molding surface is the bottom surface of the first cavity of the first mold, the outer diameter part of the annular glass gob that is expanded by centrifugal force is regulated by the side part of the first cavity. can do. Therefore, it is possible to produce flat plate-shaped glass blanks whose outer diameter is accurately dimensioned.

  A first inner diameter restricting portion is provided at the center of the first mold, and the annular glass gob is supplied unevenly to the inner diameter side so that the annular glass gob contacts the first inner diameter restricting portion. When the upper end of the portion is located above the upper surface of the annular glass gob, the inner diameter portion of the annular glass gob that is pushed and expanded by the centrifugal force can be regulated by the first inner diameter regulating portion. Accordingly, flat ring-shaped glass blanks having an accurately sized inner diameter can be produced.

  The glass blank manufacturing method described above is of a type in which molten glass is extruded by sliding the extruded member, but can also be a type in which the flow of pressurized molten glass is opened and closed by a valve member. That is, it is formed by a valve member that vertically drives a valve part that opens and closes the flow of molten glass that is fitted and inserted into an insertion hole provided in the center of the first mold, and the valve part and the insertion hole. A flat ring-shaped glass blank is manufactured using an annular passage through which molten glass flows and a first mold having a flat first molding surface, and when the valve portion is opened, the annular passage The pressurized molten glass inside flows out, and after a predetermined amount of molten glass flows out, the valve portion is closed to cut the molten glass, and the annular glass gob that has flowed out is molded on the first molding surface. A method for producing a glass blank is provided.

  According to the above method, when the valve portion is opened, the pressurized molten glass in the annular passage flows out, and after a predetermined amount of molten glass has flowed out, the valve portion is closed and the molten glass is cut out. By forming the annular glass gob on the first molding surface, it is possible to produce substantially flat ring-shaped glass blanks to which the flat first molding surface is transferred. Therefore, at least one surface of the glass blank becomes a flat molding surface, and the time and cost of post-processing can be reduced.

  The flat second molding surface of the second mold is placed opposite to the first molding surface, and the extruded annular glass gob is pressed between the first molding surface and the second molding surface to make it flat. A flat plate-shaped glass blank having a surface on which the first molding surface is transferred and a surface on which the flat second molding surface is transferred can be produced. Therefore, the upper and lower surfaces of the glass blanks become flat molding surfaces, and the post-processing time and cost can be reduced.

  In order to flatly spread the annular glass gob that has flowed out onto the first molding surface, the first mold is rotated and the extruded annular glass gob is molded on the first molding surface by centrifugal force, Flat plate-shaped glass blanks on which a flat first molding surface is transferred can be produced. Therefore, at least one surface of the glass blank becomes a flat molding surface, and the time and cost of post-processing can be reduced.

  Since the outer diameter portion of the mold includes the outer diameter restricting portion and the surplus glass escape portion, the outer diameter portion of the flat plate-shaped glass blanks is also restricted, and post-processing can be further reduced.

  When the molten glass is cooled, the molten glass and the mold are cooled together while the molten glass is in contact with the inner diameter restriction portion. It becomes difficult to release. Therefore, it is configured such that the thermal expansion coefficient of the inner diameter regulating portion of the mold is larger than the thermal expansion coefficient of glass.

  By processing the glass blanks manufactured by the method described above, a glass substrate for information recording media can be produced.

  Below, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 1st embodiment of this invention are demonstrated in detail, referring FIG. In addition, although this application demonstrates the glass blanks and glass substrate used for the glass substrate for information recording media, etc., it can utilize also for another flat ring-shaped glass product.

  FIG. 1 is a diagram schematically illustrating a method for producing flat plate-shaped glass blanks 6 according to the first embodiment of the present invention.

  The first mold 10 includes a cylindrical central guide shaft body 18 at the center of the cylindrical block body, and a first forming surface 15 obtained by processing the upper surface of the block body flat.

  A generally annular passage 12 is provided between the block body and the central guide shaft body 18. The substantially annular passage 12 is connected to a straight tubular introduction passage 12a connected to a tank (not shown) in which the molten glass 2 is stored. The molten glass 2 in the tank is supplied to the substantially annular passage 12 through the introduction passage 12a while being pressurized. The first molding surface 15 of the generally annular passage 12 is formed with an outflow hole 11 that opens in a generally annular shape. A generally annular pushing member 30 is inserted into the generally annular passage 12 so as to slide on the wall surface of the generally annular passage 12. The pushing member 30 moves up and down at a predetermined timing along the generally annular passage 12 by a driving means and a timing control means (not shown). The upper surface 32 of the generally annular pushing member 30 has a flat ring shape.

  Similarly, the 2nd metal mold | die 20 is provided with the 2nd formation surface 25 which processed the lower surface of the block body flatly.

  The first molding surface 15 is formed by a plurality of heaters 40 and temperature sensors respectively arranged around the first molding surface 15 of the first mold 10, the second molding surface 25 of the second mold 20, and the generally annular passage 12. In addition, the second mold 20 and the generally annular passage 12 are individually maintained at an appropriate temperature. The temperatures of the first molding surface 15 and the second mold 20 are maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  In the first mold 10, the second mold 20, and the extrusion member 30, cast iron can be used for a portion in contact with the molten glass 2.

  In the present specification, the term “substantially annular” means an annular shape itself, a superposition of two concentric hexagons having different sizes, or two concentric shapes having different sizes. A superposition of two star shapes, a superposition of two or more concentric polygons of different sizes, and a ratio of the major axis length to the minor axis length of about 1.1 to 2 And two concentric ellipses with different diameters are also included.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 1A, when the upper surface 32 of the pushing member 30 is pushed down along the generally annular passage 12 to a position below the introduction passage 12a, the molten glass 2 flows into the generally annular passage 12. Thus, a predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. As shown in FIG. 1B, the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and the upper surface 32, the first molding surface 15 and the center guide of the extrusion member 30 are positioned. The glass gob 4 is placed on the upper surface 18 a of the shaft body 18.

  The flat second molding surface 25 of the second mold 20 is disposed in parallel to the first molding surface 15 on which the glass gob 4 is placed, and the second mold 20 is moved downward to move the glass gob. 4 is press-molded between a flat first molding surface 15 and a flat second molding surface 25 to produce glass blanks 6. After press molding, a gas such as air is blown onto the molds 10 and 20 to cool the glass blanks 6. After cooling, the molds 10 and 20 are opened, and the glass blanks 6 are taken out from the molds 10 and 20.

  The taken-out glass blanks 6 have a flat ring shape in which the inner and outer side surfaces are free surfaces and the upper and lower surfaces are flat molding surfaces accurately transferring the flat molding surfaces 15 and 25 of the molds 10 and 20. The shape accuracy of the parallelism, flatness and inner / outer diameter is excellent. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 2nd embodiment of this invention are demonstrated in detail, referring FIG. Since the basic configuration is the same as that of the first embodiment described above, differences will be mainly described.

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. An excess space 16 is provided in the outer surface portion of the first cavity 14. The first mold 10 includes a cylindrical center guide shaft 18 at the center of the cylindrical block body. The center guide shaft body 18 includes a concave inner diameter restricting portion 18b on the upper surface thereof, and the bottom of the inner diameter restricting portion 18b constitutes a flat molding surface. The molding surface of the inner diameter regulating portion 18 b is on the same plane as the first molding surface 15. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The 2nd metal mold | die 20 is equipped with the concave 2nd cavity 24 in the lower part of a cylindrical block body. The second cavity 24 has a flat second molding surface 25 at the bottom thereof. A surplus space 26 is provided in the outer surface portion of the second cavity 24. A heater 40 is disposed above the block body, and the temperature of the second mold 20 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The depth of each of the cavities 14 and 24 is sized to be slightly larger than about half of the desired thickness of the glass blank 6.

  In the first mold 10, the second mold 20, and the extrusion member 30, cast iron can be used for a portion in contact with the molten glass 2. It is preferable that the thermal expansion coefficient of the center guide shaft body 18 of the first mold 10 is larger than the thermal expansion coefficient of the molten glass 2.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 2A, when the upper surface 32 of the pushing member 30 is pushed down along the generally annular passage 12 to a position below the introduction passage 12a, the molten glass 2 flows into the generally annular passage 12. A predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. 2B, the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and the upper surface 32, the first molding surface 15 and the center guide of the extrusion member 30 are positioned. On the molding surface of the inner diameter regulating portion 18b of the shaft body 18, the glass gob 4 that is unevenly arranged on the inner diameter side is placed.

  The flat second molding surface 25 of the second mold 20 is disposed in parallel to the first molding surface 15 on which the glass gob 4 is placed, and the second mold 20 is moved downward to move the glass gob. 4 is press-molded between a flat first molding surface 15 and a flat second molding surface 25 to produce glass blanks 6. After press molding, a gas such as air is blown onto the molds 10 and 20 to cool the glass blanks 6. After cooling, the molds 10 and 20 are opened, and the glass blanks 6 are taken out from the molds 10 and 20.

  The glass blanks 6 taken out have a molding surface whose inner surface is regulated by the inner diameter regulating portion 18b and the inner diameter regulating portion of the second mold 20, and the outer surface is a free surface due to the presence of the excess spaces 16 and 26. The upper and lower surfaces have a flat ring shape that is a flat molding surface that accurately transfers the flat molding surfaces 15 and 25 of the molds 10 and 20, and the shape accuracy of the parallelism, flatness, and inner and outer diameters is excellent. ing. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 3rd embodiment of this invention are demonstrated in detail, referring FIG. The basic configuration is the same as that of the second embodiment described above, but is different from that of the second embodiment in that the center guide shaft body 18 is configured to be elastically retractable. .

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. An excess space 16 is provided in the outer surface portion of the first cavity 14. The first mold 10 includes a cylindrical center guide shaft 18 at the center of the cylindrical block body. The side surface of the center guide shaft body 18 constitutes an inner diameter regulating portion. Behind the center guide shaft 18 is provided an urging means such as a spring for elastically urging the center guide shaft 18 upward. The center guide shaft 18 can take a protruding position where the upper surface protrudes above the upper surface of the glass gob 4 and a retracted position where the upper surface is retracted. At the protruding position, the center guide shaft body 18 protrudes elastically upward by the biasing means. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The 2nd metal mold | die 20 is equipped with the concave 2nd cavity 24 in the lower part of a cylindrical block body. The second cavity 24 has a flat second molding surface 25 at the bottom thereof. A surplus space 26 is provided in the outer surface portion of the second cavity 24. A heater 40 is disposed above the block body, and the temperature of the second mold 20 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The depth of each of the cavities 14 and 24 is sized to be slightly larger than about half of the desired thickness of the glass blank 6.

  In the first mold 10, the second mold 20, and the extrusion member 30, cast iron can be used for a portion in contact with the molten glass 2. It is preferable that the thermal expansion coefficient of the center guide shaft body 18 of the first mold 10 is larger than the thermal expansion coefficient of the molten glass 2.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 3A, when the upper surface 32 of the pushing member 30 is pushed down along the generally annular passage 12 to a position below the introduction passage 12a, the molten glass 2 flows into the generally annular passage 12. A predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. Then, as shown in FIG. 3 (B), the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and on the upper surface 32 of the extrusion member 30 and the first molding surface 15. The glass gob 4 that is unevenly arranged on the inner diameter side is placed. The inner surface of the glass gob 4 is in contact with the outer surface of the pushing member 30.

  The flat second molding surface 25 of the second mold 20 is disposed in parallel to the first molding surface 15 on which the glass gob 4 is placed, and the second mold 20 is moved downward to move the glass gob. 4 is press-molded between a flat first molding surface 15 and a flat second molding surface 25 to produce glass blanks 6. After press molding, a gas such as air is blown onto the molds 10 and 20 to cool the glass blanks 6. After cooling, the molds 10 and 20 are opened, and the glass blanks 6 are taken out from the molds 10 and 20.

  The glass blanks 6 taken out have an inner surface which is a molding surface regulated by the outer surface of the extrusion member 30 and an inner diameter regulating portion of the second mold 20, and the outer surface becomes a free surface due to the presence of the surplus spaces 16 and 26. In addition, the upper and lower surfaces have a flat ring shape that is a flat molding surface that accurately transfers the flat molding surfaces 15 and 25 of the molds 10 and 20, and the shape accuracy of parallelism, flatness, and inner and outer diameters. Is excellent. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, a glass blank manufacturing method and a glass substrate manufacturing method according to a fourth embodiment of the present invention will be described in detail with reference to FIG. Since the basic configuration is the same as that of the first embodiment described above, differences will be mainly described.

  The first mold 10 includes a cylindrical central guide shaft body 18 at the center of the cylindrical block body, and a first forming surface 15 obtained by processing the upper surface of the block body flat.

  A generally annular passage 12 is provided between the block body and the central guide shaft body 18. The substantially annular passage 12 is connected to a straight tubular introduction passage 12a connected to a tank (not shown) in which the molten glass 2 is stored. The molten glass 2 in the tank is supplied to the substantially annular passage 12 through the introduction passage 12a while being pressurized. The first molding surface 15 of the generally annular passage 12 is formed with an outflow hole 11 that opens in a generally annular shape. A generally annular pushing member 30 is inserted into the generally annular passage 12 so as to slide along the wall surface of the generally annular passage 12. The pushing member 30 moves up and down at a predetermined timing along the generally annular passage 12 by a driving means and a timing control means (not shown). The upper surface 32 of the generally annular pushing member 30 has a flat ring shape.

  The first molding surface 15 and the generally annular passage 12 are individually maintained at an appropriate temperature by a plurality of heaters 40 and temperature sensors respectively disposed around the first molding surface 15 and the generally annular passage 12 of the first mold 10. Has been. The temperature of the first molding surface 15 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  A rotation drive device such as a motor (not shown) is connected to the first mold 10, and the first mold 10 is configured to be rotationally driven together with the central guide shaft body 18.

  In the first mold 10 and the extruded member 30, cast iron can be used for a portion in contact with the molten glass 2.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 4A, when the upper surface 32 of the pushing member 30 is pushed down to a position below the introduction passage 12a along the generally annular passage 12, the molten glass 2 flows into the generally annular passage 12. A predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. As shown in FIG. 4B, the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and the upper surface 32, the first molding surface 15 and the center guide of the extrusion member 30 are positioned. The glass gob 4 is placed on the upper surface 18 a of the shaft body 18.

  As shown in FIG. 4C, by rotating the first mold 10 in a state where the glass gob 4 is placed on the first molding surface 15, the glass gob 4 is made flat by centrifugal force. The glass blanks 6 formed by pressing outward along the surface 15 are produced. After molding by centrifugal force, a gas such as air is blown onto the glass blank 6 or the first mold 10 to cool the glass blank 6. After cooling, the glass blanks 6 are taken out from the first mold 10.

  The taken-out glass blanks 6 have a substantially flat plate ring whose inner side surface, outer side surface, and upper surface are free surfaces, and whose lower surface is a flat molding surface accurately transferring the flat first molding surface 15 of the first mold 10. The shape accuracy of the parallelism, flatness and inner / outer diameter is excellent. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 5th embodiment of this invention are demonstrated in detail, referring FIG. Since the basic configuration is the same as that of the fourth embodiment described above, the differences will be mainly described.

  The first mold 10 includes a cylindrical central guide shaft body 18 at the center of the cylindrical block body, and a first forming surface 15 obtained by processing the upper surface of the block body flat.

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. The first mold 10 includes a cylindrical center guide shaft 18 at the center of the cylindrical block body. The center guide shaft body 18 includes a concave inner diameter restricting portion 18b on the upper surface thereof, and the bottom of the inner diameter restricting portion 18b constitutes a flat molding surface. The molding surface of the inner diameter regulating portion 18 b is on the same plane as the first molding surface 15. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  A generally annular passage 12 is provided between the block body and the central guide shaft body 18. The substantially annular passage 12 is connected to a straight tubular introduction passage 12a connected to a tank (not shown) in which the molten glass 2 is stored. The molten glass 2 in the tank is supplied to the substantially annular passage 12 through the introduction passage 12a while being pressurized. The first molding surface 15 of the generally annular passage 12 is formed with an outflow hole 11 that opens in a generally annular shape. A generally annular pushing member 30 is inserted into the generally annular passage 12 so as to slide along the wall surface of the generally annular passage 12. The pushing member 30 moves up and down at a predetermined timing along the generally annular passage 12 by a driving means and a timing control means (not shown). The upper surface 32 of the generally annular pushing member 30 has a flat ring shape.

  A rotation drive device such as a motor (not shown) is connected to the first mold 10, and the first mold 10 is configured to be rotationally driven together with the central guide shaft body 18.

  In the first mold 10 and the extruded member 30, cast iron can be used for a portion in contact with the molten glass 2.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 5A, when the upper surface 32 of the pushing member 30 is pushed down along the generally annular passage 12 to a position below the introduction passage 12a, the molten glass 2 flows into the generally annular passage 12. A predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. Then, as shown in FIG. 5B, the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and the upper surface 32, the first molding surface 15 and the center guide of the extrusion member 30 are positioned. The glass gob 4 is placed on the upper surface 18 a of the shaft body 18.

  As shown in FIG. 5C, the glass gob 4 is centrifuged by rotating the first mold 10 in a state where the glass gob 4 is placed on the upper surface 32 and the first molding surface 15 of the extrusion member 30. The glass blanks 6 are formed by pressing outwardly along the flat first molding surface 15 of the first cavity 14 by force. After molding by centrifugal force, a gas such as air is blown onto the glass blank 6 or the first mold 10 to cool the glass blank 6. After cooling, the glass blanks 6 are taken out from the first mold 10.

  The taken-out glass blank 6 has an inner surface and an upper surface that are free surfaces, a lower surface that is a flat molding surface that accurately transfers the flat first molding surface 15 of the first cavity 14, and an outer surface that is the cavity 14. It has a generally flat ring shape, which is a molding surface to which the outer surface is transferred, and has excellent parallelism, flatness, and shape accuracy of inner and outer diameters. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 6th embodiment of this invention are demonstrated in detail, referring FIG. The basic configuration is the same as that of the fifth embodiment described above, but is different from that of the second embodiment in that the center guide shaft body 18 protrudes from the upper end of the first mold 10. ing.

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. The first mold 10 includes a cylindrical center guide shaft 18 at the center of the cylindrical block body. The side surface of the center guide shaft body 18 constitutes an inner diameter regulating portion. The center guide shaft body 18 is in a projecting position where the upper surface projects upward from the upper surface of the glass gob 4. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  In the first mold 10, the central guide shaft body 18, and the extrusion member 30, cast iron can be used for a portion that contacts the molten glass 2. It is preferable that the thermal expansion coefficient of the center guide shaft body 18 of the first mold 10 is larger than the thermal expansion coefficient of the molten glass 2.

The inside of the introduction passage 12a connected to the first mold 10 arranged horizontally is filled with the molten glass 2 supplied from the tank. As shown in FIG. 6A, when the upper surface 32 of the pushing member 30 is pushed down along the generally annular passage 12 to a position below the introduction passage 12a, the molten glass 2 flows into the generally annular passage 12. A predetermined amount of the molten glass 2 is filled in the generally annular passage 12. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the upper surface of the pushing member 30 is pushed up along the generally annular passage 12 to a position above the introduction passage 12a, the molten glass 2 from the introduction passage 12a is cut and the molten glass to the substantially annular passage 12 is cut. 2 is blocked. As the pushing member 30 is further pushed up, the molten glass 2 in the generally annular passage 12 is also pushed up, and the molten glass 2 flows out from the substantially annular outflow hole 11. Then, as shown in FIG. 6B, the upper surface 32 of the extrusion member 30 is positioned so as to be on the same plane as the first molding surface 15, and the upper surface 32 of the extrusion member 30 and the first molding surface 15 are positioned. The glass gob 4 that is unevenly arranged on the inner diameter side is placed. The inner surface of the glass gob 4 is in contact with the outer surface of the pushing member 30.

  As shown in FIG. 6C, the glass gob 4 is placed on the upper surface 32 and the first molding surface 15 of the extrusion member 30, and the inner surface of the glass gob 4 is in contact with the outer surface of the extrusion member 30. By rotating the first mold 10, the glass blanks 6 are formed by the glass gob 4 being spread outwardly along the flat first molding surface 15 of the first cavity 14 by centrifugal force. After molding by centrifugal force, a gas such as air is blown onto the glass blank 6 or the first mold 10 to cool the glass blank 6. After cooling, the glass blanks 6 are taken out from the first mold 10.

  The glass blanks 6 taken out have an upper surface that is a free surface, a lower surface that is a flat molding surface that accurately transfers the flat first molding surface 15 of the first cavity 14, and an inner surface that is an outer surface of the extrusion member 30. The outer surface is a substantially flat ring shape that is the molding surface to which the outer surface of the cavity 14 is transferred, and the parallelism, flatness, and shape accuracy of the inner and outer diameters are excellent. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 7th embodiment of this invention are demonstrated in detail, referring FIG. Since the basic configuration is the same as that of the second embodiment described above, the differences will be mainly described.

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. An excess space 16 is provided in the outer surface portion of the first cavity 14. A valve member 50 having a substantially T-shaped cross section is disposed inside the insertion hole 13 at the center of the cylindrical block body of the first mold 10. The valve member 50 includes a generally disc-shaped valve portion 52 at the upper portion thereof. The valve portion 52 has an inner diameter regulating portion 54 having a flat molded bottom surface and a molded inner side surface, and the side portion of the valve portion 52 is in sliding contact with the wall surface of the insertion hole 13. The bottom surface of the inner diameter regulating portion 54 is on the same plane as the first molding surface 15. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The 2nd metal mold | die 20 is equipped with the concave 2nd cavity 24 in the lower part of a cylindrical block body. The second cavity 24 has a flat second molding surface 25 at the bottom thereof. A surplus space 26 is provided in the outer surface portion of the second cavity 24. A heater 40 is disposed above the block body, and the temperature of the second mold 20 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  The depth of each of the cavities 14 and 24 is sized to be slightly larger than about half of the desired thickness of the glass blank 6.

  In the first mold 10, the second mold 20, and the valve member 50, cast iron can be used for a portion in contact with the molten glass 2. It is preferable that the thermal expansion coefficient of the valve member 50 as the inner diameter regulating member is configured to be larger than the thermal expansion coefficient of the molten glass 2.

As shown in FIG. 7A, in the introduction passage 12a and the generally annular passage 12 connected to the first mold 10 arranged horizontally, the pressurized molten glass supplied from the tank is provided. 2 is filled. As shown in FIG. 7B, when the valve portion 52 of the valve member 50 is pushed up along the generally annular passage 12, the valve portion 52 comes into contact with the second mold 20 disposed so as to be opposed to the valve member 50. Annular passage 12 opens. The pressurized molten glass 2 flows out into the first cavity 14 from the opening circulation hole 11 in a substantially annular shape, and a predetermined amount of the molten glass 2 is filled into the first cavity 14. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the second mold 20 is pushed down, the valve portion 52 of the valve member 50 in contact with the second mold 20 is pushed down along the generally annular passage 12. As a result, the valve portion 52 cuts the molten glass 2 flowing out from the generally annular passage 12 and the valve portion 52 closes the flow hole 11. When the second mold 20 is pushed down to a predetermined press position, the molding bottom surface of the valve portion 52 of the valve member 50 is on the same plane as the first molding surface 15 as shown in FIG. The glass gob 4 is press-formed between the flat first molding surface 15 and the flat second molding surface 25 in a state where the glass melt is positioned and the molten glass 2 is unevenly distributed on the inner diameter side of the first cavity 14 and the second cavity 24. Glass blanks 6 are produced. After press molding, a gas such as air is blown onto the molds 10 and 20 to cool the glass blanks 6. After cooling, the molds 10 and 20 are opened, and the glass blanks 6 are taken out from the molds 10 and 20.

  The glass blanks 6 taken out have a molding surface whose inner side surface is regulated by the inner diameter regulation part 54 and the inner diameter regulation part of the second mold 20, and the outer side surface is a free surface due to the presence of the surplus spaces 16 and 26. The upper and lower surfaces have a flat ring shape that is a flat molding surface that accurately transfers the flat molding surfaces 15 and 25 of the molds 10 and 20, and the shape accuracy of the parallelism, flatness, and inner and outer diameters is excellent. ing. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, the manufacturing method of the glass blanks and the manufacturing method of a glass substrate which concern on 8th embodiment of this invention are demonstrated in detail, referring FIG. Since the basic configuration is the same as that of the seventh embodiment described above, the differences will be mainly described.

  The first mold 10 is provided with a concave first cavity 14 at the top of a cylindrical block body. The first cavity 14 has a substantially annular outflow hole 11 at the center thereof, and a flat first molding surface 15 at the bottom thereof. A substantially T-shaped valve member 50 is provided inside the insertion hole 13 at the center of the cylindrical block body of the first mold 10. The valve member 50 includes a generally disc-shaped valve portion 52 at the upper portion thereof. The valve part 52 has a flat molded upper surface, and the side part of the valve part 52 is in sliding contact with the wall surface of the insertion hole 13. The flat molding upper surface is flush with the first molding surface 15. A heater 40 is disposed below the block body, and the temperature of the first mold 10 is maintained at the glass transition temperature ± 50 ° C. of the molten glass 2.

  In the first mold 10 valve member 50, cast iron can be used for a portion in contact with the molten glass 2.

As shown in FIG. 8 (A), inside the introduction passage 12a and the generally annular passage 12 connected to the first mold 10 arranged horizontally, the pressurized molten glass supplied from the tank is provided. 2 is filled. As shown in FIG. 8B, when the valve portion 52 of the valve member 50 is pushed up along the generally annular passage 12, the generally annular passage 12 opens. The pressurized molten glass 2 flows out into the first cavity 14 from the opening circulation hole 11 in a substantially annular shape, and a predetermined amount of the molten glass 2 is filled into the first cavity 14. The viscosity of the molten glass 2 is, for example, 3 × 10 ^{2 to} 1 × 10 ³ poise.

  When the valve portion 52 of the valve member 50 is pushed down along the generally annular passage 12, the valve portion 52 cuts the molten glass 2 flowing out from the substantially annular passage 12 and the valve portion 52 closes the flow hole 11. When the first mold 10 is pushed down to a predetermined molding position, the molding upper surface of the valve portion 52 of the valve member 50 is on the same plane as the first molding surface 15 as shown in FIG. Positioned. The glass gob 4 is placed on the molding upper surface and the first molding surface 15 of the valve member 50.

  As shown in FIG. 8D, by rotating the first mold 10 together with the valve member 50 in a state where the glass gob 4 is placed on the molding upper surface of the valve member 50 and the first molding surface 15, Glass blanks 6 are produced in which the glass gob 4 is expanded outwardly along the flat first molding surface 15 of the first cavity 14 by centrifugal force. After molding by centrifugal force, a gas such as air is blown onto the glass blank 6 or the first mold 10 to cool the glass blank 6. After cooling, the glass blanks 6 are taken out from the first mold 10.

  The taken-out glass blank 6 has an inner surface and an upper surface that are free surfaces, a lower surface that is a flat molding surface that accurately transfers the flat first molding surface 15 of the first cavity 14, and an outer surface that is the cavity 14. It has a generally flat ring shape, which is a molding surface to which the outer surface is transferred, and has excellent parallelism, flatness, and shape accuracy of inner and outer diameters. Thereafter, the glass blanks 6 are subjected to grinding processing, polishing processing, and the like to be a glass substrate for an information recording medium. Accordingly, the flat ring-shaped glass blanks 6 can reduce the time and cost burden of post-processing such as grinding performed thereafter.

  Next, a glass blank manufacturing method and a glass substrate manufacturing method according to the ninth embodiment of the present invention will be described in detail with reference to FIG. 9, but the second embodiment, the third embodiment, and the third embodiment described above. In the seventh embodiment, the first mold and the second mold are additionally provided.

  The supply amount and supply location of the molten glass 2 delivered to the first cavity 14 are accompanied by some variation as a practical problem. In the case where only the inner diameter is restricted, this variation is allowed by changing the outer diameter. However, the outer diameter portion of the molded glass blanks 6 usually has a curved shape that is not completely circular, and is different from the generally flat ring shape that is originally required.

  Therefore, as shown in FIG. 9, in at least one of the first mold 10 and the second mold 20, the outer diameter regulating surfaces 16 a and 26 a and the surplus glass escape portions 17 and 27 are formed on the outer portions of the cavities 14 and 24. And are provided. The outer diameter regulating surfaces 16 a and 26 a extend in a circumferential shape so as to be orthogonal to the mold dividing surface, and are for regulating the outer diameter of the glass blanks 6. The surplus glass escape portions 17 and 27 are spaces extending in an annular shape on the outer portions of the outer diameter regulating surfaces 16a and 26a, and are used to absorb the excess molten glass 2 protruding from the cavities 14 and 24. Is. The volume of the surplus glass escape portions 17 and 27 depends on the supply accuracy of the molten glass 2 but is about 5% of the volume of the cavities 14 and 24.

  The molten glass 2 to the 1st cavity 14 is supplied a little more than the case in said 2nd embodiment, 3rd embodiment, and 7th embodiment so that it may reach to the outer diameter control surface 16a, 26a. While extending to the outer diameter regulating surfaces 16 a and 26 a in the cavities 14 and 24, the excess molten glass 2 protrudes into the surplus glass escape portions 17 and 27 and becomes the side surplus portion 8. Since the outer surface 7 of the glass blank 6 is also regulated by the outer diameter regulating surfaces 16a and 26a, it can be made closer to the shape of the desired glass blank for information recording medium and the glass substrate. Therefore, since the processing amount of the side surplus portion 8 is small, it is possible to further reduce the time and cost burden of post-processing such as grinding.

  In addition, in the 1st metal mold | die 10, the 2nd metal mold | die 20, the extrusion member 30, and the valve member 50, as a material of the part which contact | connects the molten glass 2, cast iron may be sufficient, but heat resistance is higher and it is hard to react with glass, A material having high hardness, high thermal conductivity, and being difficult to oxidize, or a material lined with other metals or ceramics to supplement the surface properties may be used. Moreover, ceramics etc. which are not metals may be sufficient. In addition, the method of cooling the glass blanks 6 after shaping | molding may be methods other than spraying gas.

It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 1st embodiment of this invention. It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 2nd embodiment of this invention. It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 3rd embodiment of this invention. It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 4th embodiment of this invention. It is a figure which illustrates typically the manufacturing method of the flat ring-shaped glass blanks which concern on 5th embodiment of this invention. It is a figure which illustrates typically the manufacturing method of the flat ring-shaped glass blank which concerns on 6th embodiment of this invention. It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 7th embodiment of this invention. It is a figure which illustrates typically the preparation methods of the flat ring-shaped glass blanks which concern on 8th embodiment of this invention. It is a figure which illustrates typically the manufacturing method of the flat ring-shaped glass blanks which concern on 9th embodiment of this invention.

Explanation of symbols

2 Molten glass 4 Glass gob 6 Glass blank 7 Outer side 8 Side surplus part 10 First mold 11 Outflow hole 12 Circular passage 12a Inlet passage 13 Insertion hole 14 First cavity 15 First molding surface 16 Excess space 16a Outer diameter regulating surface 17 Excess glass escape portion 18 Center guide shaft body 18a Upper surface 18b Inner diameter restricting portion 20 Second mold 24 Second cavity 25 Second molding surface 26 Excess space 26a Outer diameter restricting surface 28 Insertion hole 30 Extruding member 32 Upper surface 40 Heater 50 Valve Member 52 Valve portion 54 Inner diameter regulating portion

Claims (13)

A flat ring-shaped glass blank is manufactured using an annular passage through which molten glass flows and a first mold having a flat first molding surface, and an extruded member that slides in the annular passage. And
A glass characterized in that a molten glass in an annular passage is cut and extruded by sliding an extruded member along the annular passage, and the extruded annular glass gob is formed on a first molding surface. Blanks manufacturing method. Place the flat second molding surface of the second mold opposite the first molding surface,
The method for producing glass blanks according to claim 1, wherein the extruded annular glass gob is press-molded between the first molding surface and the second molding surface. A first inner diameter restricting portion and a second inner diameter restricting portion are provided in the center of the first die and the second die,
3. An annular glass gob distributed unevenly on the inner diameter side is press-molded, and an inner diameter portion of the annular glass gob is regulated by a first inner diameter regulating portion and a second inner diameter regulating portion. The manufacturing method of the glass blank of description.   4. The glass according to claim 3, wherein an upper end of the inner diameter regulating portion is located above an upper surface of the annular glass gob, and the inner diameter regulating portion moves downward when press-molding with the second mold. Blanks manufacturing method.   The method for producing glass blanks according to claim 1, wherein the first mold is rotated and the extruded annular glass gob is formed on the first molding surface by centrifugal force.   The method for producing glass blanks according to claim 5, wherein the first molding surface is a bottom surface of the first cavity of the first mold. Provide the first inner diameter restriction part in the center of the first mold,
The annular glass gob is supplied unevenly to the inner diameter side so that the annular glass gob contacts the first inner diameter regulating portion, and the upper end of the first inner diameter regulating portion is located above the upper surface of the annular glass gob. The manufacturing method of the glass blanks of Claim 5 characterized by the above-mentioned. A valve member that vertically drives a valve portion that opens and closes the flow of the molten glass that is fitted and inserted into an insertion hole provided in the center of the first mold;
An annular passage formed by the valve portion and the insertion hole, through which the molten glass flows,
A method of producing flat plate ring-shaped glass blanks using a first mold having a flat first molding surface,
When the valve portion is opened, the pressurized molten glass in the annular passage flows out, and after a predetermined amount of molten glass has flowed out, the valve portion is closed to cut the molten glass, and the annular glass gob that has flowed out is The manufacturing method of the glass blanks characterized by shape | molding on one shaping | molding surface. Place the flat second molding surface of the second mold opposite the first molding surface,
The method for producing glass blanks according to claim 8, wherein the extruded annular glass gob is press-molded between the first molding surface and the second molding surface.   The method for producing glass blanks according to claim 8, wherein the first mold is rotated and the extruded annular glass gob is formed on the first molding surface by centrifugal force.   The method for producing glass blanks according to any one of claims 2, 3, 4, and 9, wherein the outer diameter portion of the mold includes an outer diameter regulating portion and an excess glass escape portion. .   The method for producing glass blanks according to any one of claims 3, 4, and 7, wherein a coefficient of thermal expansion of an inner diameter regulating portion of the mold is larger than a coefficient of thermal expansion of glass.   A method for producing a glass substrate for an information recording medium, comprising processing a glass blank produced by the method according to claim 1 to produce a glass substrate for an information recording medium.

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