JPH0262722A - Production of aluminum substrate for memory disk - Google Patents

Abstract

PURPOSE:To produce an aluminum substrate for memory disks having small surface roughness and high flatness and to improve productivity by applying a lubricating agent on the pressurizing surfaces of dies and executing coining. CONSTITUTION:The lubricating agent is applied from a spraying device on the respective pressurizing surfaces of the upper and lower dies 2, 3 of a coining device and an aluminum blank material 4 is placed on the lower die 2. The upper die 3 is disposed to face the material and the pressurizing force of the upper die 3 is set at 4 times the tensile strength of the blank material 4 to pressurize the material in a die ring 1. The surface roughness and flatness after the coining are better than in the case of applying the lubricating agent on the surface of the aluminum blank material 4 according to this production. In addition, the number of the coined sheets before the generation of build-up is increased. The aluminum substrate for memory disks having the small surface roughness and the high flatness is produced in this way and since the number of the coined sheets before the generation of the built-up is increased, the number of die exchange is decreased and the productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing an aluminum substrate for a memory disk with a smooth surface from an aluminum blank material.

Note that the aluminum blank material herein means a blank material made of aluminum, an aluminum alloy, or a composite material thereof, and the aluminum substrate also has the same meaning.

[Conventional technology and its issues]

Memory disks used in external storage devices for electronic computers usually have a structure in which the surface of an aluminum substrate is coated with a magnetic material.

Memory disks require a high level of flatness and smoothness in order to accurately read and write with a magnetic head, but the surface condition of a memory disk depends on the surface condition of the aluminum substrate, so the aluminum substrate has extremely high dimensions. Precision and high quality surface condition are required.

Conventionally, methods for manufacturing such aluminum substrates for memory disks include (a) ultra-precision cutting of an aluminum blank material using a natural diamond cutting tool; A method of simultaneously polishing both sides with abrasive grains and hot water using
However, since all of these processes involve cutting or grinding, they have the problem of being time-consuming and low productivity.

[Means for solving problems and their effects]

For this reason, recently, a method of manufacturing aluminum substrates for memory disks by coining has been studied.

As shown in Figure 1, this method uses aluminum blank material l
is sandwiched between two dies 3 and 4 with smooth pressing surfaces in a die ring 2 that regulates the spread limit of the material, and pressurized.
An aluminum substrate for a memory disk is manufactured by coining the smooth surfaces of the dies 3 and 4 onto an aluminum blank material 1. Since this method is a press method, it has the advantage of being much more productive than cutting or grinding.

When implementing this method, it is necessary to interpose a lubricant between the die and the aluminum blank to prevent seizure, etc., but initially this lubricant was It was applied to the surface of aluminum blank material. However, various experiments have shown that when the same amount of lubricant is applied to the surface of an aluminum blank material, and when it is applied to the pressurized surface of a die, the latter has a smaller surface roughness and a lower flatness. It has become clear that high quality aluminum substrates for memory disks can be manufactured, and build-up (adhesion of aluminum to the pressurized surface of the die) is less likely to occur. This is thought to be because the pressurizing surface of the die is extremely smooth, so that an extremely uniform lubricating film is formed.

The present invention was made based on the above findings, and involves inserting an aluminum blank material between two dies with smooth pressing surfaces in a die ring that regulates the limit of material spread, and performing coining processing. The method for manufacturing an aluminum substrate for a memory disk is characterized in that a lubricant is applied to a pressurizing surface of the die.

Note that the method of applying the lubricant is not particularly limited, but it is desirable to use a high-precision coating device that can reduce variation in the amount of application to 20% or less of the average amount of application.

〔Example〕

The present invention will be explained in detail below.

A circular blank material was manufactured from a plate material of J I 55086 (AI-Ag alloy)-0 material (tensile strength σ-27 Kg/e1 m') with a thickness of 1 and 5 ms. The outer diameter of the blank material is the inner diameter of the die ring 1 (A-65+u+
), the rate of decrease in thickness of the blank material due to coining was set to be 0.5%.

Using a spray device, apply 30 mg of lubricant to the pressure surfaces of the upper and lower dies 2 and 3 of the coining device as shown in Figure 1.
The aluminum blank material 4 is placed on the lower die 2, the upper die 3 is opposed to it, and the pressing force of the upper die 3 is applied in the die ring 1 to 108 kg/m+s" (the tensile strength of the blank material 4 is The pressure was set to 4 times the height of the The surface roughness Ra of the pressing surfaces of the dies 2 and 3 was 0.020 μm, and the surface roughness Ra of the aluminum blank 4 was 0.20IJIw. As the lubricant, 06316 manufactured by Nippon Craft Oil Co., Ltd. was used.

For comparison, no lubricant was applied to the pressurizing surface of the die, but the same amount (30 mg/+++'') of the same lubricant as above was applied to the surface of the aluminum blank material 4, and pressure was applied under the same conditions as above. did.

The surface roughness Ra and warpage (flatness) of the aluminum substrate obtained by coining were measured. In addition, we continuously coined aluminum blanks, observed the occurrence of build-up on the pressing surface of the die, and determined the number of coins until build-up occurred.

The results were as shown in Table-1.

Table 1 As is clear from Table 1, applying lubricant to the pressure surface of the die provides better surface roughness and flatness after coining than applying lubricant to the surface of the aluminum blank. It can also be seen that the number of coined sheets until build-up occurs also increases.

〔Effect of the invention〕

As explained above, according to the present invention, when manufacturing an aluminum substrate for a memory disk by coining, by applying a lubricant to the pressing surface of the die, the surface roughness can be reduced (and the memory disk with high flatness can be manufactured). Since it is possible to manufacture aluminum substrates for use in aluminum substrates, and the number of sheets to be coined can be increased before build-up occurs, the number of die exchanges can be reduced, which has the advantage of further improving productivity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a coining machine. 1: die ring, 2: lower die, 3: upper die, 4 aluminum blank material. Figure-

Claims (1)

[Claims] 1. In a method of manufacturing an aluminum substrate for a memory disk by sandwiching an aluminum blank material between two dies with smooth pressure surfaces in a die ring that regulates the spread limit of the material, and performing a coining process, the above-mentioned die A method for manufacturing an aluminum substrate for a memory disk, the method comprising applying a lubricant to the pressurized surface of the memory disk.