JP7228007B2 - Plate material for annealing treatment, method for manufacturing plate material for annealing treatment, and method for manufacturing substrate - Google Patents

Description

TECHNICAL FIELD The present invention relates to an annealing plate material used for annealing a blank material, a method for manufacturing the plate material for annealing processing, and a method for manufacturing a substrate.

2. Description of the Related Art Today, personal computers, DVD (Digital Versatile Disc) recording devices, and the like incorporate a hard disk device (HDD: Hard Disk Drive) for data recording. 2. Description of the Related Art A hard disk drive uses a magnetic disk having a magnetic layer on a substrate, and magnetically recorded information is recorded or read on the magnetic layer by a magnetic head slightly floated above the surface of the magnetic disk. As the substrate of this magnetic disk, a metal substrate (aluminum substrate) or a glass substrate having a property of being less likely to be plastically deformed than a metal substrate or the like is preferably used.

For example, a glass substrate for a magnetic disk is produced by subjecting a plate-shaped glass blank material to machining such as grinding and polishing. Glass blanks may be annealed to remove strain prior to machining. As a conventional annealing treatment, a method called a setter is known in which a laminate obtained by alternately stacking plate materials and glass blank materials is subjected to heat treatment (Patent Document 1). By performing such an annealing treatment, it is possible not only to remove the strain, but also to reduce the flatness of the glass blank and to improve the surface properties of the glass blank.

Japanese Patent No. 6238282

In the above-described conventional method, after the annealing treatment, the glass blank is recovered by alternately taking out the setter and the glass blank from the laminate. However, when the setter is taken out, the glass blank material may stick to the lower surface of the setter and be taken out of the laminate together with the setter. In this case, in order to recover the glass blank material, it is necessary to separate (remove) the glass blank material stuck to the setter from the setter, which reduces the work efficiency and the productivity of the glass substrate. In addition, the glass blank material stuck to the lower surface of the setter and lifted may fall and be cracked, chipped, or scratched. A glass blank material damaged in this manner becomes unsuitable as a base plate for glass substrates, and the yield of glass substrates may decrease.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plate material for annealing treatment that can be easily separated from the laminated plate material for annealing treatment and a blank material. Another object of the present invention is to provide a method for manufacturing such a plate material for annealing treatment, and a method for manufacturing a magnetic disk substrate using such a plate material for annealing treatment.

One aspect of the present invention is a plate material for annealing treatment,
One of a plurality of plate materials used for annealing treatment of a plate-shaped blank material and laminated so as to sandwich the blank material from both sides,
having a pair of main surfaces, at least one of which is in contact with the blank;
It is characterized by comprising one or a plurality of through-holes that are open to the main surface and pass through the plate member.

Preferably, the main surface has an arithmetic mean roughness adjusted so that air flows between the laminated plate material and the blank material.

It is preferable that the total arithmetic mean roughness of the main surface of the plate material and the main surface of the blank material in contact with the main surface is 0.2 μm or more.

It is preferable that the arithmetic mean roughness of the main surface of the plate material is larger than the arithmetic mean roughness of the main surface of the blank material in contact with the main surface.

The arithmetic average roughness of the main surface of the plate is preferably 0.2 to 1.0 μm.

At least one of the through-holes is preferably open to the main surface of the plate so that an edge of the plate surrounding the at least one through-hole abuts the main surface of the blank.

The shape of the through-hole opened in the main surface of the plate material is circular,
It is preferable that the through-hole has a diameter of 1 to 6 mm.

It is preferable that a plurality of through-holes are provided and are opened in a dispersed manner within the main surface of the plate member.

When the main surface of the plate member is divided into a plurality of regions having equal areas, it is preferable that the plurality of through holes are arranged in the same number in each of the regions.

A position where a circular hole is formed is set in the blank material,
It is preferable that the through-hole is opened in a region of the main surface of the plate material that contacts the portion of the blank material to which the position is set.

A side wall of the plate surrounding the through-hole is preferably chamfered so that a cross-sectional area of the through-hole along a direction parallel to the main surface of the plate increases as it approaches the main surface of the plate. .

Another aspect of the present invention is a method for manufacturing a plate material for annealing treatment,
A method for manufacturing one of a plurality of plate materials that are used for annealing a plate-shaped blank material and laminated so as to sandwich the blank material from both sides,
The plate material is
having a pair of main surfaces, at least one of which is in contact with the blank;
One or more through-holes that are open to the main surface and pass through the plate,
The manufacturing method includes a molding process for molding the raw material powder of the plate material filled in the molding die,
The molding die has a projecting portion projecting from an inner wall surface of the molding die so that the through hole is formed in the plate material.

Another aspect of the present invention is a substrate manufacturing method, comprising:
A laminate obtained by laminating at least two plate materials of the plate material for annealing treatment or the plate material for annealing treatment manufactured by the method for manufacturing the plate material for annealing treatment so as to sandwich a plate-like blank material from both sides is heated, and the blank is heated. Annealing treatment for annealing the material is provided.

According to the present invention, it is possible to easily separate the laminated plate material for annealing treatment and the blank material.

1 is an external perspective view showing an example of a plate material for annealing treatment; FIG. It is sectional drawing which shows the shape of the outer periphery of a board|plate material. (a), (b) is a figure which shows the state which took out the board|plate material from the laminated body. (a) to (d) are diagrams for explaining the flow of air passing through a through hole. (a) to (c) are diagrams for explaining another example of air flow through a through-hole. [Fig. 2] is a diagram showing a jig for loading and unloading plate materials from a stack. It is a figure which shows the cross section near the through-hole of a board|plate material. It is a figure which shows the modification of a board|plate material. It is a figure which shows the other modification of a board|plate material. 1. It is a figure explaining the annealing process performed using the board|plate material of FIG.

An annealing plate material, a method for manufacturing an annealing plate material, and a method for manufacturing a magnetic disk substrate according to embodiments of the present invention will be described below in detail.

(plate material for annealing treatment)
The plate material for annealing treatment (hereinafter referred to as plate material) of the present embodiment will be described. This embodiment includes various embodiments described later.
FIG. 1 shows a plate material 10 of this embodiment.
The plate member 10 is one of a plurality of plate members used for annealing a glass blank, which is an example of the blank. The plate materials 10 are laminated so as to sandwich a plate-shaped glass blank material from both sides when annealing is performed.

The plate material 10 has a pair of main surfaces 1a, 1b, at least one of which is in contact with the glass blank material. The main surfaces 1a, 1b of the plate member 10 are substantially circular. As used herein, the term “substantially circular” includes a perfect circular shape and an elliptical shape. It may consist of a circular arc.

The diameter of the plate material 10 is, for example, 1.05 to 1.5 times the diameter of the glass blank material. Here, if the diameter of the plate material 10 is smaller than the diameter of the glass blank material, the outer peripheral portion of the glass blank material laminated on the plate material 10 is deformed along the outer peripheral side end surface of the plate material 10 during the annealing treatment, By transferring the outer shape of the plate material 10 to the glass blank material 20, the main surface of the glass blank material is left with a mark (transfer mark), which may deteriorate the flatness of the glass blank material. On the other hand, if the diameter of the plate material 10 is too large, the number of laminates that can be placed in a heating furnace (described later) during the annealing process decreases, which may reduce the productivity of the glass blank material. In addition, when the glass blank material and the plate material 10 are laminated, the amount of mutual deviation between the center positions becomes large, and the center of gravity of the laminated body is biased, deteriorating the stability, and the laminated body may fall or tilt during transportation. be. From this point of view, the diameter of the plate material 10 is preferably 1.05 to 1.2 times the diameter of the glass blank material 20 .

The main surfaces 1a and 1b of the plate 10 are preferably larger than the main surfaces of the glass blank so that the glass blank laminated with the plate 10 does not protrude from the main surfaces 1a and 1b. As a result, the flatness can be reduced over the entire area of the glass blank, and the grinding allowance of the glass blank in the grinding process and the polishing process can be reduced, or the grinding process or the polishing process can be omitted. Therefore, the productivity of the magnetic disk glass substrate is improved.

The flatness of the plate member 10 is preferably smaller than the flatness of the glass blank in order to reduce the flatness of the glass blank. The flatness of the plate material 10 is, for example, 10 μm or less. Flatness is measured using a flatness measuring machine.

It is preferable that the coefficient of thermal expansion of the material of the plate material 10 is close to the coefficient of thermal expansion of the material of the glass blank material. If the difference in thermal expansion coefficient between the plate material 10 and the glass blank material is large, a large stress is generated in the glass blank material during the annealing process due to the difference in the amount of thermal expansion and the amount of thermal contraction between the two, and the glass blank material is deformed after the annealing process. may remain on the material. Therefore, the ratio of the coefficient of thermal expansion of the plate material 10 to the coefficient of thermal expansion of the glass blank material is preferably 0.9 to 1.1 in the temperature range from room temperature to the annealing temperature. A thermal expansion coefficient is a coefficient of linear expansion measured by thermomechanical analysis in accordance with JIS R1618:2002. When the material of the glass blank material 20 is aluminosilicate glass, the thermal expansion coefficient of the plate material 10 is, for example, 3 to 10×10 ^-6 /°C in the temperature range of 100°C to 300°C.

The thermal conductivity of the material of the plate material 10 is preferably greater than that of the material of the glass blank material 20 . Since the plate material 10 has a high thermal conductivity, heat can be sufficiently transferred to the glass blank material laminated with the plate material 10 during the annealing process. Thermal conductivity refers to a value calculated according to JIS R1611:2010. The thermal conductivity of the plate material 10 is, for example, 1 to 150 W/m·K at room temperature to 300°C.

Examples of materials for the plate material 10 include metal oxides, metal carbides, metal nitrides, metal borides, and materials containing two or more of these. Specific examples of these materials include alumina (Al ₂ O ₃ ), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), sialon (Si ₃ N ₄ ·Al ₂ O ₃ ), steatite, spinel, cordierite and the like. Among them, alumina (Al ₂ O ₃ ) and silicon carbide (SiC) are preferably used.

The thickness of the plate material 10 is, for example, 1 to 3 mm. A specific example of the thickness of the plate member 10 is 1.5 mm.

The end face shape of the plate member 10 may be a shape extending linearly perpendicular to the main surfaces 1a and 1b, or a chamfered shape at the ends intersecting the main surfaces 1a and 1b. Examples of the shape of the chamfered end surface include the cross-sectional shape shown in FIG. FIG. 2 is a cross-sectional view showing the shape of the outer circumference of the plate member 10. As shown in FIG. In the example shown in FIG. 2, the chamfered end has a convexly curved shape with respect to the interior of the plate member 10, and the length L1 of the chamfered end in the direction parallel to the main surfaces 1a and 1b is , for example 0.2 to 0.4 mm, preferably 0.3 mm. The length L2 of the chamfered ends in the direction orthogonal to the main surfaces 1a and 1b (thickness direction) is, for example, 0.05 to 0.2 mm, preferably 0.1 mm.

As shown in FIG. 1, the plate member 10 has one or a plurality of through holes 2 that are open to the main surfaces 1a and 1b and pass through the plate member 10. As shown in FIG. The through holes 2 are specifically opened at positions on the main surfaces 1a, 1b such that air flows into the gap between the laminated plate material 10 and the glass blank material. Since such through-holes 2 are provided in the plate material 10, when the plate material 10 is removed from the laminate 30 (see FIG. 10) after the annealing treatment, the plate material 10 and the glass blank material 20 are separated from each other as described below. (see FIG. 10), the glass blank material 20 is suppressed from sticking to the plate material 10 . From this point of view, at least one of the through-holes 2 is provided so that the edge of the plate member 10 surrounding the open end of the at least one through-hole 2 is in contact with the main surface of the glass blank 20 .

3(a) and 3(b) are diagrams showing a state in which the plate material is taken out from the laminate, and FIG. The case where the board|plate material 10 of a form is used is each shown.
The conventional plate material 100 is not provided with a through hole penetrating the plate material 100, and when the plate material 100 is lifted from the laminated body after the annealing treatment, as shown in FIG. It sticks to the lower surface of the plate material 100 and is lifted together with the plate material 100.例文帳に追加This is because a small gap between the lower surface of the plate 100 and the upper surface of the glass blank 20 tends to widen due to the weight of the glass blank 20, and the pressure in this gap becomes lower than the surrounding pressure (atmospheric pressure). It is thought that it will become Such sticking of the glass blank material 20 occurs more remarkably as the plate materials 100 are quickly loaded and unloaded in order to improve the working efficiency of recovering the glass blank material 20 .
On the other hand, as shown in FIG. 3B, the plate member 10 of the present embodiment is provided with the through holes 2. Therefore, when the plate member 10 is lifted, the gap between the plate member 10 and the glass blank member 20 Air can flow into through the through hole 2 . Therefore, the glass blank material 20 does not stick to the plate material 10, and only the plate material 10 is lifted. In the example shown in FIG. 3B, since the through-holes 2 are open to the atmosphere, when the plate member 10 is lifted, the air above the plate member 10 can flow downward through the through-holes 2. . Thus, according to this embodiment, sticking of the glass blank material 20 to the plate material 10 can be suppressed, and the plate material 10 and the glass blank material 20 can be easily separated. Therefore, the glass blank material 20 can be recovered efficiently. Moreover, it is possible to prevent the glass blank material 20 stuck to the plate material 10 from falling.

Here, with reference to FIG. 4, the flow of air passing through the through holes 2 will be described. 4(a) to 4(d), the plate materials 10A, 10B, 10C and the glass blank materials 20A, 20B are alternately stacked on the pedestal 60 as an example, and the air passing through the through hole 2 is shown. Flows are indicated by arrows. Two through holes 2 are provided in each of the plate members 10A to 10C. 4(a) to 4(d), the surface roughness of the main surfaces of the glass blank materials 20A and 20B is exaggerated. As used herein, surface roughness refers to arithmetic mean roughness Ra (JIS B0601:2001).
Between the main surfaces of the plate material and the main surface of the glass blank material facing each other, there is a gap due to the surface roughness of the plate material and the glass blank material, which communicates with the through hole 2 of the plate material. Therefore, air can flow between the plate material 10A and the glass blank material 20A as indicated by the double arrow in FIG. 4(a). Here, when the plate member 10A is lifted, air can flow from above the plate member 10A through the through holes 2 into the gap between the plate member 10A and the glass blank member 20A. At this time, an air flow is also formed that flows from the side of the glass blank material 20A into the through hole 2 through the gap between the plate material 10A and the glass blank material 20A. In this manner, air flows between the plate member 10A and the glass blank member 20A when the plate member 10A is lifted, thereby suppressing the glass blank member 20A from sticking to the plate member 10A.

Further, since the through-holes 2 of the plate material 10B communicate with the gap between the glass blank material 20A and the plate material 10B and the gap between the glass blank material 20B and the plate material 10B, the plate material 10A is removed from the laminate. In this state, air can flow as indicated by the double arrow in FIG. 4(b). Therefore, when the glass blank material 20A is lifted, the glass blank material 20A can be taken out without the plate material 10B sticking to the glass blank material 20A.
In addition, when the glass blank material 20A is removed from the laminate, air can flow as indicated by the double arrow in FIG. 4(c). Sticking of the material 20B is suppressed.

The through hole 2 of the plate material 10C communicates with the gap between the glass blank material 20B and the plate material 10C. No air flow is formed through it. Therefore, measures are taken as shown in FIGS. 5(a) to 5(c) so that air can flow between the plate member 10C positioned at the bottom of the laminate and the pedestal 60. is preferred.
In the example shown in FIG. 5A, the surface roughness of the main surface of the plate material 10C on the pedestal 60 side is large, and a gap exists between the plate material 10C and the pedestal 60. Air can flow, like an arrow. Therefore, when the glass blank material 20B is lifted, the glass blank material 20B can be taken out without the plate material 10C sticking to the glass blank material 20B.
In the example shown in FIG. 5B, the surface roughness of the pedestal 60 is large, and a gap exists between the plate member 10C and the pedestal 60. As indicated by the double arrow shown in FIG. air can flow. Therefore, when the glass blank material 20B is lifted, the glass blank material 20B can be taken out without the plate material 10C sticking to the glass blank material 20B.
In the example shown in FIG. 5C, a cavity region S is formed in a portion including the surface of the pedestal 60. In the example shown in FIG. The hollow region S communicates with the through hole 2 of the plate member 10C and also communicates with the space on the outer peripheral side of the plate member 10C. Therefore, air can flow as indicated by the double-headed arrow shown in FIG. 5(c). Therefore, when the glass blank material 20B is lifted, the glass blank material 20B can be taken out without the plate material 10C sticking to the glass blank material 20B.

The air flowing through the gaps and through-holes 2 described above is not limited to air in the atmosphere communicating with the gaps and through-holes 2, and may be air supplied from the outside separately from the atmosphere. Such air can be supplied, for example, using a jig 50 (see FIG. 6) for loading and unloading the board 10 . FIG. 6 shows a jig 50 for taking out the plate material 10 and the glass blank material from the laminate. The jig 50 includes suction cups 51 and a suction mechanism (not shown), and can convey the plate material 10 while sucking the main surface of the plate material 10 against the suction cups 51 . The jig 50 also has a supply mechanism (not shown) that supplies air toward the through hole 2 . Air is supplied from the jig 50 toward the through-holes 2, and air flows between the plate material 10 and the glass blank material 20 in contact with the plate material 10 through the through-holes 2. Therefore, the sucked plate material The glass blank material 20 can be suppressed from sticking to the plate material 10 when the plate material 10 is lifted, and the plate material 10 and the glass blank material 20 can be easily separated.

According to one embodiment, the sum of the arithmetic mean roughness Ra1 of the main surface of the plate material 10 and the arithmetic mean roughness Ra2 of the main surface of the glass blank 20 in contact with the main surface is 0.2 μm or more. preferable. When the total arithmetic mean roughness is 0.2 μm or more, a sufficient gap is secured between the laminated plate material 10 and the glass blank material 20, so that the plate material 10 and the glass blank material are separated through the through hole 2. Air can flow into the gap between the glass blank material 20 and the plate material 10, and sticking to the glass blank material 20 and the plate material 10 is suppressed. The arithmetic mean roughness Ra is measured by a stylus roughness meter (contact roughness measuring instrument) using a stylus.
In this embodiment, according to a further embodiment, it is preferable to satisfy Ra1>Ra2. By satisfying such a relationship, the effect of suppressing sticking of the glass blank material 20 to the plate material 10 is increased.

According to one embodiment, the arithmetic mean roughness Ra1 of the main surface of the plate 10 is preferably 0.2-1.0 μm. When Ra1 is less than 0.2 μm, it is difficult for air to pass between the plate material 10 and the glass blank material 20, and the glass blank material 20 easily sticks to the plate material 10. Therefore, it takes time to remove the glass blank material 20 from the plate material 10. As a result, work efficiency tends to decrease. Moreover, if Ra1 is less than 0.2 μm, the manufacturing cost of the plate material 10 for reducing the arithmetic mean roughness increases. On the other hand, if Ra1 exceeds 1.0 μm, fine particles may be detached from the plate material 10 due to contact between the glass blank material 20 and the plate material 10, and dust may be generated. Fine particles detached from the plate adhere to the surface of the glass blank material 20 , contaminate the glass blank material 20 , and sometimes damage the surface of the glass blank material 20 . Moreover, when Ra1 exceeds 1.0 μm, particularly when it is 1.3 μm or more, a special process is required to increase the arithmetic mean roughness, which increases the manufacturing cost of the plate material 10 . A preferable arithmetic mean roughness Ra1 of the main surface of the plate member 10 is, for example, 0.6 μm.

The arithmetic mean roughness Ra2 of the main surface of the glass blank material 20 is, for example, 0.001 to 1.3 μm. A preferred specific example of the arithmetic mean roughness Ra2 is 0.7 μm.

According to one embodiment, the shape of the through-holes 2 opened in the main surfaces 1a, 1b of the plate 10 is circular, and the diameter of the through-holes 2 is preferably 1-6 mm. When the diameter of the through-hole 2 exceeds 6 mm, the glass blank material 20 laminated with the plate material 10 is deformed so as to slightly enter the through-hole 2 during the annealing process, and the opening of the through-hole 2 is formed. The shape is transferred to the glass blank 20, and the main surface of the glass blank 20 may be left with a mark (transfer mark). For this reason, the flatness of the glass blank material 20 may deteriorate. The glass blank material 20 with such marks tends to be unsuitable as a base plate for a magnetic disk glass substrate. Moreover, when the diameter of the through hole 2 is less than 1 mm, it is difficult for air to flow between the plate material 10 and the glass blank material 20, and the air flow tends to deteriorate. For this reason, it takes time to separate the glass blank material 20 from the plate material 10, and there is a possibility that the work efficiency is lowered. Moreover, if the diameter of the through-hole 2 is less than 1 mm, the manufacturing cost of the through-hole 2 increases. The diameter of through hole 2 is more preferably 2 to 5 mm.

According to one embodiment, the position where the circular hole is formed (circular hole forming position) is set in the glass blank material 20 . The circular hole is, for example, a circular hole that is concentric with the outer circumference of the glass blank material 20 . In this case, it is preferable that through-holes 2 are provided in areas of main surfaces 1a and 1b of plate material 10 that are in contact with portions of glass blank material 20 where circular hole forming positions are set. When the through holes 2 are provided in such a region, even if the glass blank material 20 has a transfer mark, it is removed from the glass blank material 20, so the transfer mark of the glass blank material 20 has no influence. . In addition, the circular hole forming position is set to a portion including the center of the main surface of the glass blank material 20 .

According to one embodiment, as shown in FIG. 7, the side wall 3 of the plate member 10 surrounding the through hole 2 extends along the direction parallel to the main surface 1a or 1b of the plate member 10 (horizontal direction in FIG. 7). It is preferable that the cross-sectional area of 2 is chamfered so that it becomes larger as it approaches the main surface 1a or 1b of the plate member 10 . FIG. 7 is a diagram showing a cross section of the plate member 10 near the through hole 2. As shown in FIG. In the example shown in FIG. 7, the chamfered portion of the side wall 3 of the plate member 10 has an inclined wall surface 3a that is inclined with respect to the plate thickness direction of the plate member 10 . Since the side walls 3 of the plate material 10 are chamfered in this way, when the glass blank material 20 is deformed so as to leave the above-described transfer traces in the annealing process, the amount of deformation can be reduced. 20 can be prevented from deteriorating in flatness. Such an inclined wall surface 3a is effective when the through holes 2 are provided in the regions of the main surfaces 1a and 1b of the plate member 10 that are in contact with the portion of the glass blank member 20 excluding the positions where the circular holes are formed. The inclination angle of the inclined wall surface 3a with respect to the extending direction of the wall surface of the side wall 3 (the wall surface between the inclined wall surfaces 3a on both sides) excluding the inclined wall surface 3a is preferably 30 to 60°, for example, 45°. The cross-sectional shape of the chamfered portion of the side wall 3 of the plate member 10 is not limited to a linear shape as shown in FIG. It may be in shape.

According to one embodiment, the through-holes 2 are preferably provided in plurality and open distributed in the main surfaces 1a, 1b. This increases the effect of suppressing sticking of the glass blank material 20 to the plate material 10 . The number of through-holes 2 is, for example, 1, 2, 3, 4, 5 or more.
As for the plurality of through holes 2, as shown in FIG. 8, when the main surfaces 1a and 1b of the plate member 10 are divided into a plurality of regions having the same area, the same number of through holes 2 are arranged in each of the plurality of regions. Preferably, for example, one through-hole 2 is arranged in each region. FIG. 8 is a diagram showing a modification of the plate member 10. As shown in FIG. In the example shown in FIG. 8, each of the main surfaces 1a and 1b of the plate member 10 is divided into four regions by two imaginary lines (broken lines) perpendicular to each other at the center of the main surfaces 1a and 1b. 2 is arranged.
On the other hand, when the number of through-holes 2 increases, the possibility of generating transfer traces on the glass blank material 20 increases. Therefore, the preferable number of through-holes 2 provided in the plate member 10 is 1-4. Moreover, in this embodiment, as described above, it is also preferable to provide the through holes 2 in the regions of the main surfaces 1a and 1b that are in contact with the portions of the glass blank 20 where the circular hole forming positions are set. It is also preferable to reduce the opening area of each of the through holes 2 or to reduce the total opening area of the through holes 2 .

The opening shape of the through hole 2 of the plate member 10 is not limited to a substantially circular shape, and may be polygonal, or a shape extending in one or more directions along the extending direction of the plate member 10, or the like. As an example of the shape extending in one direction, a shape extending along the circumferential direction of the plate member 10 can be cited as shown in FIG. FIG. 9 is a diagram showing another modification of the plate member 10. As shown in FIG. Shapes extending in a plurality of directions include shapes extending in three or more directions (for example, a Y shape and a cross shape).
Further, the extending direction of the through hole 2 is not limited to the direction parallel to the plate thickness direction, and may be a direction inclined with respect to the plate thickness direction. Moreover, the through-hole 2 may extend curvedly or bent between the portions on both sides in the extending direction of the through-hole 2 .

The above-described plate material 10 can also be used for annealing treatment of blank materials other than glass blank materials, such as aluminum blank materials.

(Manufacturing method of plate material)
Next, a method for manufacturing the plate material of this embodiment will be described. This embodiment includes various embodiments described later.
The plate material manufacturing method is a method for manufacturing one of a plurality of plate materials that are used for annealing treatment of a glass blank material and are laminated so as to sandwich a plate-shaped glass blank material from both sides.
The plate member has a pair of main surfaces, at least one of which is in contact with the glass blank, and is provided with one or more through-holes that are open to the main surfaces and pass through the plate member. That is, the plate material is the same as the plate material 10 described above.
This manufacturing method includes a forming process for forming the raw material powder of the plate material filled in the forming die.
The molding die has a projecting portion projecting from the inner wall surface of the molding die so as to form a through hole in the plate material.
According to this manufacturing method, a plate material having through holes can be manufactured by the molding process, and can be manufactured at a lower cost than the case where a raw plate material without through holes is perforated to form through holes. can. For example, the plate material made of the metal compound material is hard, and it is costly to drill holes using a tool such as a drill or a laser.

In the molding process, for example, cold isostatic pressing (CIP) can be used for molding, followed by degreasing and sintering. The sintering may be performed by a normal pressure sintering method, but it is preferable to perform compaction by performing a gas pressure sintering method or hot isostatic pressing (HIP) after sintering.
Using the method for manufacturing a plate as described above, it is also possible to manufacture a plate used for annealing blanks other than glass blanks, such as aluminum blanks.

(substrate for magnetic disk)
Next, the magnetic disk substrate of this embodiment will be described. In this embodiment, a glass for magnetic disk having a nominal size of 2.5 to 3.5 inches (diameter of 65 to 95 mm) and a plate thickness of 0.1 to 1.5 mm, preferably a plate thickness of 0.3 to 0.9 mm Suitable for manufacturing substrates.
A glass substrate for a magnetic disk has a disk shape. The magnetic-disk glass substrate may be ring-shaped with a center hole concentric with the outer circumference of the magnetic-disk glass substrate. A magnetic disk is formed by forming magnetic layers (recording areas) in annular regions on both sides of a magnetic disk glass substrate.

(Blank material for magnetic disk)
A magnetic-disk glass blank material (hereinafter simply referred to as a glass blank material), which is an example of a magnetic-disk blank material, is a glass plate produced by a press molding process, and is before a grinding process to be described later. . The glass blank material is not limited to one produced by press molding, and may be one produced using a method such as a float method or a fusion method. The shape of the glass blank material is substantially circular. Further, the glass blank material may have circular holes formed by a circular hole forming process to be described later.
As a material for the glass blank material, aluminosilicate glass, soda lime glass, borosilicate glass, or the like can be used. In particular, aluminosilicate glass can be preferably used because it can be chemically strengthened and a glass substrate for a magnetic disk having excellent flatness of the main surface and strength of the substrate can be produced.

(Manufacturing method of substrate for magnetic disk)
Next, a method for manufacturing the magnetic disk substrate of this embodiment will be described. This embodiment includes various embodiments described later.
First, a glass blank material is produced by press-molding a molten glass lump that is a material for a plate-shaped glass substrate for a magnetic disk having a pair of main surfaces (press-molding process). Next, a heat treatment is performed to remove distortion of the glass blank material (annealing treatment). After the annealing treatment, a circular hole is formed in the central portion of the glass blank material to form a ring shape (annular shape) (circular hole forming process).
Next, shape processing is performed on the glass blank material by end face grinding (shape processing). Thereby, a ring-shaped (annular) glass substrate is produced. Next, the main surface is ground with fixed abrasive grains (grinding process), and the flattened glass substrate is edge-polished (edge-polishing process). Next, the main surface of the glass substrate is subjected to first polishing (first polishing process). Next, if necessary, the glass substrate is chemically strengthened (chemical strengthening treatment). Next, the chemically strengthened glass substrate is subjected to second polishing (second polishing process). A magnetic disk glass substrate is obtained through the above processes. Each process will be described in detail below.

(a) Press molding process A molten glass flow is cut by a cutter, and the cut molten glass gob is sandwiched between the pressing surfaces of a pair of molds and pressed to form a glass blank. In the present embodiment, as will be described later, after the tip of the molten glass flow is dropped on the upper surface of the lower mold, the molten glass flow is cut at a position on the upstream side to form a lump of molten glass. A glass blank material is molded by pressing the mass downward with an upper mold.
After pressing for a predetermined time, the mold is opened and the glass blank material is taken out.

(b) Annealing Treatment In the annealing treatment, the glass blank material is annealed by heating a laminated body in which a plurality of plate materials are laminated so as to sandwich the glass blank material from both sides. The plate member 10 described above is used as the plate member. Specifically, as shown in FIG. 10, the laminated body is configured by alternately stacking plate materials 10 and glass blank materials 20 . The number of plate members 10 is one more than the number of glass blank members 20 (for example, 10 to 30), and the plate members 10 are arranged at positions including the uppermost and lowermost steps of the laminate 30 . Annealing is performed by applying a load to the uppermost layer of the laminate 30 and keeping it warm in the heating furnace 40 .

(c) Circular hole forming process A disc-shaped glass blank material having circular holes is obtained by forming circular holes (circular holes) in the glass blank material by coring, scribing, or the like.

Coring is performed by cutting a glass blank material from one main surface with a cylindrical core drill with one end open, scraping off the circumference of the circular hole, hollowing out the glass in the center (core), and creating a through hole. It is a method of forming. It should be noted that the circular cutting line (outer circle), which is the outer contour line of the glass blank, may be scraped out with a core drill while scraping off the circumference (inner circle) of the circular hole. Thereafter, a disk-shaped glass blank is obtained by removing a portion outside the outer circle and a portion inside the inner circle of the glass blank.

In scribing, a cutter (scriber) made of cemented carbide or diamond particles is used to form a circular cutting line on one main surface of the glass blank material, and then the glass blank material is heated to form a circular cutting line on the glass blank. It is a method of stretching in the thickness direction and pressing the inside of the circular cutting line to separate. A circular cutting line, which serves as the contour line of the circular hole, may be formed at the same time as the circular cutting line, which serves as the outer contour line of the glass blank. In this case, a circular cutting line (outer circle) serving as the outer contour line of the glass blank and a circular cutting line (inner circle) serving as the contour line of the circular hole are formed so as to form concentric circles. After that, by partially heating the glass blank material, due to the difference in thermal expansion of the glass blank material, the portion outside the outer circle and the portion inside the inner circle of the glass blank material are removed, resulting in a disk-like shape. A glass blank is obtained.

(d) Shape Processing Processing In the shape processing processing, chamfering is performed on the outer peripheral end portion of the glass blank material. When a circular hole is formed in the glass blank material, chamfering is also performed on the inner peripheral edge of the circular hole.

(e) Grinding Process In the grinding process, the main surface of the glass blank material is ground using a double-side grinding device equipped with a planetary gear mechanism. Specifically, both main surfaces of the glass blank are ground while holding the outer peripheral side end face of the glass blank in a holding hole provided in a holding member of the double-sided grinding device. The double-sided grinding apparatus has a pair of upper and lower surface plates (an upper surface plate and a lower surface plate), and a glass substrate is sandwiched between the upper surface plate and the lower surface plate. Then, either one or both of the upper surface plate and the lower surface plate are moved to relatively move the glass blank and each surface plate, thereby grinding both main surfaces of the glass blank. This allows the plate thickness to be adjusted and the flatness to be improved.

(f) End face polishing process In the end face polishing process, the outer peripheral side end face of the glass substrate obtained by the grinding process of the glass blank material is mirror-finished by brush polishing. When a circular hole is formed in the glass substrate, the inner peripheral side end surface of the circular hole is also mirror-finished. At this time, an abrasive slurry containing fine particles of cerium oxide or the like as free abrasive grains is used.

(g) First polishing process The first polishing process is, for example, removing scratches and distortions remaining on the main surface when grinding with fixed abrasive grains, or fine surface unevenness (micro waviness, roughness). for adjustment purposes. Specifically, the main surfaces on both sides of the glass substrate are polished while holding the outer peripheral side end surface of the glass substrate in holding holes provided in a polishing carrier of the double-sided polishing apparatus.

In the first polishing process, the glass substrate is polished while applying polishing slurry using a double-side polishing machine having the same configuration as the double-side polishing machine used in the grinding process using fixed abrasive grains. In the first polishing process, polishing slurry containing loose abrasive grains is used instead of fixed abrasive grains, unlike grinding with fixed abrasive grains.

The double-side polishing machine has a pair of upper and lower surface plates (an upper surface plate and a lower surface plate), and a glass substrate is sandwiched between the upper surface plate and the lower surface plate. A flat plate polishing pad (for example, a resin polisher) having an annular shape as a whole is attached to the upper surface of the lower surface plate and the bottom surface of the upper surface plate. Both main surfaces of the glass substrate are polished by relatively moving the glass substrate and each surface plate by moving either or both of the upper surface plate and the lower surface plate.

The glass substrate may be chemically strengthened by immersing the glass substrate after the first polishing treatment in a chemical strengthening liquid (chemical strengthening treatment). As the chemical strengthening liquid, for example, a mixed molten liquid of potassium nitrate and sodium sulfate can be used.

(h) Second Polishing (Final Polishing) Treatment The purpose of the second polishing treatment is to mirror polish the main surface. Also in the second polishing, a double-sided polishing apparatus having the same structure as the double-sided polishing apparatus used in the first polishing is used. Specifically, the main surfaces on both sides of the glass substrate are polished while holding the outer peripheral side end surface of the glass substrate in holding holes provided in a polishing carrier of the double-sided polishing apparatus. The second polishing treatment differs from the first polishing treatment in that the type and particle size of free abrasive grains are different, and the hardness of the resin polisher is different. Specifically, a polishing liquid containing colloidal silica having a particle size of about 5 to 100 nm as free abrasive grains is supplied between the polishing pad of a double-sided polishing apparatus and the main surface of the glass substrate, and the main surface of the glass substrate is polished. be. A magnetic disk glass substrate is obtained by washing the polished glass substrate with a neutral detergent, pure water, isopropyl alcohol, or the like.

In the method for manufacturing a magnetic-disk glass substrate according to the present embodiment, the plate material 10 having the through holes 2 is used for the annealing treatment. The glass blank material 20 can be recovered efficiently. For this reason, the productivity of the magnetic disk glass substrate is also improved. Moreover, when removing the board|plate material 10 after annealing treatment, it can prevent that the glass blank material 20 falls. As a result, it is possible to suppress unsuitability as a base plate for magnetic-disk glass substrates, and to suppress a decrease in the yield of magnetic-disk glass substrates.

Substrates other than glass substrates for magnetic discs, such as aluminum substrates for magnetic discs, can also be manufactured using the above substrate manufacturing method.

(Experimental example)
In order to investigate the effects of the plate material of this embodiment, annealing treatment was performed using plate materials and glass blank materials of various specifications.
Annealing was performed by assembling a laminate by combining plate materials and glass blank materials having the specifications shown in Tables 1 to 3 below. For each sample, 61 plates of the same specification and 60 glass blanks of the same specification were alternately arranged on the pedestal to form a laminate, and a weight of 500 g was placed on the top plate. Annealing treatment was performed in the heating furnace 40 shown in FIG. In addition, the board|plate material and base which were arrange|positioned at the lowest stage were taken as the form shown in FIG.5(b).

As the plate materials of samples 1 to 25, substantially circular ones made of alumina and having a diameter of 110 mm were used.
The position on the main surface of the through-hole of the plate material was positioned inside a circle concentric with the outer periphery of the plate material and having a diameter half the length of the diameter of the plate material. The shape of the through hole was a shape extending cylindrically in the plate thickness direction.
A substantially circular aluminosilicate glass blank having a diameter of 100 mm was used as the glass blank material. The glass blanks of Samples 21 to 23 were produced by the float method, and the glass blanks of the other samples were produced by press molding.

After the annealing treatment, the number of occurrences of sticking, the number of occurrences of transfer marks, and the number of contaminated glass blanks were counted in the following manner.
(1) Number of sticking occurrences The number of sticking occurrences of the glass blank material is less than 3 times out of 60 when the plate materials are loaded and unloaded one by one from the top layer. A, B when 3 times or more and less than 10 times, C when 10 times or more, A and B were evaluated as being able to suppress sticking, and C was evaluated as being unable to suppress sticking. Loading and unloading of the planks took half the time normally required.
(2) Number of generated transfer marks When visually observing the main surfaces on both sides of 60 glass blank materials, the number of sheets with transfer marks caused by through holes was less than 3 out of 60 sheets. A + if 3 or more but less than 5, B if 5 or more and less than 10, C if 10 or more but less than 15, D if 15 or more, and A + ∼ C was evaluated as being able to suppress transfer marks, and D was evaluated as not being able to suppress transfer marks.
(3) Number of Contaminated Glass Blanks The main surfaces and end faces on both sides of 60 glass blanks were observed with a grazing incidence interferometry flatness tester (Nidek FT-17), and the size of dust generated from the plate was observed. If the number of glass blank materials with a size of 1 to 100 μm attached is less than 5 out of 60, A is 5 or more and less than 10, B is 10 or more. A case was evaluated as C, A and B were evaluated as being able to suppress contamination of the glass blank material, and C was evaluated as being unable to suppress contamination of the glass blank material.
The results are shown in Tables 1-3.

From the comparison of samples 6 to 25 and samples 1 to 5, it can be seen that sticking can be suppressed by having through holes in the plate material. In addition, when the experiment was conducted under the same conditions except that Samples 22, 23, and 25 were loaded and unloaded over about twice the time (usually required time), the evaluation of the number of occurrences of sticking was B. , it was found that sticking can be suppressed. On the other hand, when the experiment was conducted under the same conditions as in Samples 4 and 5, except that the loading and unloading of the plate materials took about twice as long, the evaluation of the number of occurrences of sticking was C, indicating that sticking could not be suppressed. have understood.

As can be seen from the results of Samples 6 to 10, the smaller the number of through-holes and the smaller the hole diameter of the through-holes, the greater the effect of suppressing transfer traces. In particular, when the number of through-holes is 2 or less, or when the hole diameter of the through-holes is 6 mm or less, the effect of suppressing transfer traces is particularly large. Also, the results of samples 11 to 15 and the results of samples 16 to 20 show the same.

From the comparison between Samples 1 to 3 and Samples 4 and 5, it can be seen that the number of contaminated glass blanks can be suppressed when the arithmetic mean roughness Ra1 of the main surface of the plate material is small.

In samples 9, 14, and 19, the diameter of the plate material was changed to 95 mm, 95 mm, and 90 mm, respectively, and the annealing treatment was performed. Among them, 15 or more were generated.

Although the plate material for annealing treatment, the method for manufacturing the plate material for annealing treatment, and the method for manufacturing the substrate according to the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and is within the scope of the present invention. , of course, may have various modifications and changes.

1a, 1b main surface 2 through hole 3 side wall 3a inclined wall surface 10, 10A, 10B, 10C plate material for annealing treatment 20, 20a, 20B glass blank material 30 laminate 40 heating furnace 50 jig 60 pedestal

Claims (6)

One of a plurality of plate materials used for annealing treatment of a plate-shaped blank material and laminated so as to sandwich the blank material from both sides,
having a pair of main surfaces, at least one of which is in contact with the blank;
One or more through-holes that are open to the main surface and penetrate the plate ,
The blank material has a portion to be removed after annealing,
A plate for annealing treatment, wherein the through-holes are open only in a region of the main surface of the plate that is in contact with the removed portion of the blank. 2. The plate material for annealing treatment according to claim 1 , wherein the arithmetic mean roughness of the main surface of said plate material is larger than the arithmetic mean roughness of the main surface of said blank material in contact with said main surface. 3. The plate for annealing treatment according to claim 1, wherein the main surface of said plate has an arithmetic average roughness of 0.2 [ mu]m or more. an opening shape of the through-hole in the main surface of the plate material is circular;
The plate material for annealing treatment according to any one of claims 1 to 3 , wherein the opening shape has a diameter of 1 to 6 mm. 5. The plate material for annealing treatment according to claim 1, wherein said blank material is a blank material for magnetic disk substrates. A method of manufacturing a substrate,
Using a plurality of the plate materials for annealing treatment according to any one of claims 1 to 5 , the blank material is annealed by heating the laminated body in which the plate-like blank material is sandwiched from both sides. A method of manufacturing a substrate, comprising:

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