JPH0514147U - Spacer for aluminum disk annealing - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to find better spacers by replacing the stainless steel spacers used in the annealing process of aluminum disks. [Structure] In the annealing work of a plurality of stacked aluminum disks 1, as a spacer to be interposed between the stacked aluminum disks 1, a ceramic spacer 2 having a thermal shock resistance ΔT of 300 ° C. or higher whose upper and lower surfaces are processed with high precision is used. It is a spacer for annealing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a spacer for aluminum disk annealing.

[0002]

[Prior Art]

 As computer functions become more precise, more complicated, and more processing is performed, demands for increased storage capacity and higher speeds of external devices are increasing year by year. As a result, many users are turning to hard disk drives (HDD), and the demand for hard disk drives is increasing rapidly. In order to improve the performance of hard disk drives, it is essential to improve the performance of magnetic disks, but the performance of magnetic disks is greatly affected by the accuracy of the anodized aluminum substrate that is the base material substrate. In order to increase the storage density of a hard disk drive, it is necessary to reduce the gap between the head and magnetic disk.

Therefore, it is essential to improve the flatness and flatness of the magnetic disk. In addition, an aluminum disc has an annealing process in which it is rapidly cooled by applying a pressure of several hundred kg / cm ² at 400 to 450 ° C during the manufacturing process. As shown in FIG. 3, the aluminum disc is annealed by stacking 10 to 15 aluminum discs 101 and pressurizing the aluminum discs 101 with a stainless spacer 102 interposed therebetween.

[0004]

[Problems to be solved by the device]

The problem with the conventionally used stainless steel spacers 102 is that the stainless steel spacers 102 are thermally deformed as the temperature changes. Next, the aluminum material is easily adapted to the stainless steel material, and the aluminum dust adheres to the stainless steel spacer 102 and scratches the aluminum disc 101. Further, since a pressure of several hundred kg / cm ² is applied, the stainless steel spacer 102 is deformed. Further, the aluminum disk 101 adjacent to the stainless spacer 102 is easily damaged and cannot be used as a product and can only be used as a dummy. Furthermore, the surface finish accuracy of the stainless steel spacer 102 cannot be maintained due to changes in temperature and pressure.

[0005]

[Means for Solving the Problems]

 In view of the above circumstances, the present invention has conducted various experiments to find out whether there is a better spacer in place of the stainless steel spacer used in the annealing process of the aluminum disc. As a result, they have found that it is best to use a ceramic material such as silicon carbide, silicon nitride, or mullite instead of the stainless spacer.

Since a ceramic material has a higher Young's modulus and a smaller coefficient of thermal expansion than a stainless material, the degree of deformation due to temperature and pressure is small, and the change of the finished surface is small. In addition, since the ceramic material has extremely poor wettability with aluminum, the adhesion of aluminum dust is small and the aluminum disc is not easily scratched. In addition, ceramic materials can be machined with higher accuracy than stainless steel materials, and since deformation is less likely to occur, it is possible to improve the accuracy of aluminum disks. However, among ceramics, ordinary alumina, unlike silicon carbide, silicon nitride, and mullite, has a thermal shock resistance ΔT of lower than 300 ° C, and thus cannot be used for annealing an aluminum disk.

[0007]

【Example】

 Hereinafter, the present invention will be described in detail. The present inventors conducted various experiments in order to solve problems such as thermal deformation of the stainless spacers interposed between the stacked aluminum disks in the annealing work of the stacked aluminum disks.

In the experiment, as shown in FIG. 1, 10 to 15 aluminum discs 1 were stacked and pressure P was applied at several hundred kg / cm ² with a ceramic spacer 2 interposed between them and the temperature was 400 to 450 ° C. Let it air cool from. As a result of the experiment, it was found that it is best to use silicon carbide, silicon nitride (including sialon), and mullite ceramic materials.

Next, experimental results are shown together with their material characteristics.

[0010]

[Table 1]

Here, the thermal shock resistance ΔT is a temperature difference until cracks occur when an object to be measured is heated to a high temperature and water-cooled, and the higher the value, the better the thermal shock resistance. Further, the ceramic spacer 2 used here has a surface roughness (Rmax) of 0.8 S or less, and the flatness was conventionally 1 to 3 μm, but by setting it to 0.5 μm or less, the aluminum disk 1 Can have excellent flatness. Further, the corners of the ceramic spacer 2 are chamfered at all 1R or higher to improve chipping resistance.

Further, as shown in FIG. 2, the maximum amount of deflection of the ceramic spacer 2 was measured by applying a load to the center of the upper surface while supporting the lower surface, and the following results were obtained.

[0013]

[Table 2]

In this measurement, the thickness of the spacer was 10 mm, the outer diameter was 150 mm, and the load was 500 kg / cm ² . The relative deflection amount is the value when 1.00 is used for stainless steel. From these results, it can be seen that the ceramic spacers 2 of the present invention have a small amount of deflection as compared with the conventional stainless spacers, and in particular, at 450 ° C., the relative amount of deflection is 0.5 or less and the deformation is small.

In the above embodiments, silicon carbide, silicon nitride, and mullite are shown as the ceramic spacer 2, but various ceramics having a thermal shock resistance ΔT of 300 ° C. or more can be used.

[0016]

[Effect of the device]

 As described above, the present invention uses a ceramic spacer having a thermal shock resistance ΔT of 300 ° C or higher whose upper and lower surfaces are precisely processed as a spacer to be interposed between the stacked aluminum disks in the annealing work of a plurality of stacked aluminum disks. Since it is a spacer for annealing a minium disk, the Young's modulus of the ceramic spacer is higher than that of the stainless spacer, and the coefficient of thermal expansion is small, so the degree of deformation due to temperature and pressure is small and the change in the finished surface is small. In addition, since the ceramic spacer does not have wettability with aluminum, the amount of aluminum dust adhered to the ceramic spacer is small, and the aluminum disk is not easily scratched. In addition, the ceramic spacers can be machined with higher precision than stainless steel spacers and are less deformed, so the precision of aluminum discs can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a specific embodiment of the present invention.

FIG. 2 is a view showing a state in which a bending test of the ceramic spacer of the present invention is performed.

FIG. 3 is a vertical cross-sectional view showing an annealing operation of a conventional aluminum disk having a plurality of stacked layers.

[Explanation of symbols]

 1 ... Aluminum disc 2 ... Ceramic spacer

Claims (1)

[Scope of utility model registration request] 1. A spacer which is interposed between a plurality of stacked aluminum disks in an aluminum disk annealing step, and is made of ceramics having a thermal shock resistance ΔT of 300 ° C. or higher whose upper and lower surfaces are processed with high precision. Aluminum disc annealing spacer