JPH02247027A - Manufacture of accurate metallic disk - Google Patents

Abstract

PURPOSE:To turn the upside and downside faces of metallic disk into good flatness and smoothness by coining by making the surface roughness of the pressure face of a working die in the specified range rougher than the roughness of pressure face of a static die. CONSTITUTION:At press coining where the limit of expansion in the direction of diameter of metallic material is regulated with a die ring provided on the periphery of the pressure face of the static die, a disklike metallic material is coined by making the surface roughness of the pressure face of the working die rougher than the surface roughness of pressure face of the static die in the range of double and under. The material on the working die side of the material to be coined is liable to metal flow, but it is prevented by roughening the surface roughness. The accurate metallic disk with the good flatness and smoothness of the upside and downside face of metallic disk and the uniform and high quality is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing precision metal disks by coining.

(Prior art) Precision metal disks that require extremely smooth and flat surfaces, such as aluminum alloy substrates for memory disks, mirror plates, and rotary reflectors for encoders, are usually manufactured by precision cutting. Since the cutting process takes time and has low productivity, recently a method of performing this by coining has been proposed (Japanese Patent Laid-Open No. 61-5027287, JP-A No. 62-1.58532, JP-A No. 62-1.58532, Showa 62-157
325, JP-A-62-157326, JP-A-62-157327).

To manufacture precision metal discs by coining, a disc-shaped metal material is sandwiched between two dies with smooth pressurizing surfaces, pressurized, and a die ring placed around the dies is used to press the disc-shaped metal material in the radial direction of the metal material. A method is used in which the smooth surface of the die is coined onto the metal material with the spread limit regulated.

(Problem to be Solved by the Invention) Conventionally, in such coining processing, it is important to apply pressure to the disc-shaped metal material to cause the metal to flow uniformly in the radial direction. There is a difference in metal flow in the radial direction between the die side surface and the stationary die side surface, and as a result, the flatness and smoothness of the resulting precision metal disc differs on each surface, making it difficult to stabilize dimensional accuracy. It was difficult.

An object of the present invention is to solve the problems of the prior art described above and provide a method for manufacturing precision metal disks with stable dimensional accuracy.

(Means for Solving the Problems) The above objects of the present invention are (1) to produce a disk-shaped metal material between a moving die with a smooth pressurizing surface (hereinafter simply referred to as a moving die) and a stationary die (hereinafter simply referred to as a stationary die). When applying pressure by sandwiching the metal material between the pressurizing surfaces (called dies), a die ring placed around the pressurizing surface of the stationary die performs a coining process to limit the spread of the metal material in the radial direction, producing precision metal discs. A precision metal disc characterized in that the coining process is performed by roughening the surface roughness of the pressure surface of the movable die within a range of twice or less than the surface roughness of the pressure surface of the stationary die. (2) When a disc-shaped metal material having a hole in the center is sandwiched between a movable die with a smooth pressurizing surface and a stationary die and pressurized, the method is arranged around the pressurizing surface of the stationary die. A method for manufacturing a precision metal disk by performing a coining process to limit the spread of material in the radial direction on the outer circumferential surface of a mandrel disposed at the center of the inner circumferential surface and pressurizing surface of a die ring, the method comprising: This was achieved by a method for manufacturing a precision metal disk, characterized in that the coining process is performed by roughening the surface roughness of the pressurizing surface of the die to within twice the surface roughness of the pressurizing surface of the stationary die. .

In the present invention, as described above, the surface roughness of the pressing surface of the moving die is made rougher than that of the pressing surface of the stationary die. This is to prevent a difference in metal flow between the top and bottom surfaces of the material to be coined. On the other hand, when coining is performed using two dies with the same surface roughness,
When the material is set on the stationary lower die and the upper die is operated to perform the coining process, metal flow is easier on the upper surface than on the lower surface, and the way the microscopic surface irregularities are crushed is the same as that on the upper and lower surfaces. It will be different.

In addition, in the present invention, the surface roughness of the pressure surface of the movable die is made to be within twice the surface roughness of the pressure surface of the stationary die. This is because if the surface roughness is more than twice the surface roughness of the pressurizing surface, the difference in surface roughness will be too excessive and a precision metal disk with stable flatness and smoothness cannot be obtained.

Furthermore, in the present invention, a lubricant is applied to the surface of the material in order to suppress build-up (adhesion of material to the pressing surface of the die) during coining, and the preferred type of lubricant is oil with low viscosity. For example, G6316 manufactured by Nippon Craft Oil ■ etc. can be mentioned.

Further, the method of applying the lubricant is not particularly limited, but a method using an electrostatic coating device or a high-precision spray device is superior in terms of uniform coating.

The method of the present invention is particularly suitable for manufacturing aluminum alloy substrates for memory disks that require high dimensional accuracy.

Further, the above-mentioned contents also apply to the case where a precision metal disk having a hole in the center is manufactured by coining.

(Examples) Hereinafter, the present invention will be described in further detail based on Examples.

A circular blank material with an outer diameter of 65 mm was produced by punching out a plate material of 5086-0 (Aρ-Mg alloy) with a thickness of 1.5 mm.

Coining was performed using dies whose pressurizing surfaces had different surface roughnesses, keeping the pressurizing conditions constant, so that the outer diameter of the blank material was 66 mm.

The lubricant used is G6316 manufactured by Nippon Craft Oil, and the amount applied was 30mg/rr? It was held constant.

The surface roughness and flatness of five precision metal disks obtained after coining were measured for warpage, and the average values thereof are shown in Table 1. In the same table, the upper surface is the surface on the moving upper die side, and the lower surface is the surface on the stationary lower die side.

As is clear from the results in Table 1, in the samples of the present invention, there is no difference in surface roughness and flatness between the upper and lower surfaces. However, in the comparative example, there is a large difference in surface roughness and flatness between the upper and lower surfaces.

(Effects of the Invention) As described above, according to the present invention, it is possible to manufacture a precision metal disk with good flatness and smoothness on the upper and lower surfaces of the metal disk, and which is uniform and of high quality. The precision metal disk according to the present invention can be preferably used as an aluminum alloy substrate for memory disks, a mirror plate, a rotating reflector plate for encoders, and the like.

Patent applicant Furukawa Aluminum Industries Co., Ltd. Kawasaki Steel Corporation

Claims (2)

[Claims] (1) When pressurizing a disc-shaped metal material by sandwiching it between a moving die with a smooth pressurizing surface (hereinafter simply referred to as a moving die) and a stationary die (hereinafter simply referred to as a stationary die), A method for manufacturing a precision metal disk by performing a coining process that restricts the limit of radial spread of a metal material using a die ring disposed around the pressurizing surface of the die, the surface roughness of the pressurizing surface of the movable die being A method for manufacturing a precision metal disk, characterized in that the coining process is performed by making the surface roughness within twice the surface roughness of the pressurizing surface of the stationary die. (2) When pressurizing a disc-shaped metal material with a hole in the center between a movable die with a smooth pressurizing surface and a stationary die, the inside of the die ring placed around the pressurizing surface of the stationary die is used. A method for manufacturing a precision metal disk by performing a coining process to limit the spread of material in the radial direction on the outer circumferential surface of a mandrel disposed at the center of the circumferential surface and the pressurizing surface, the pressurizing surface of the movable die A method for manufacturing a precision metal disk, characterized in that the coining process is performed by increasing the surface roughness of the pressurizing surface of the stationary die to within twice the surface roughness of the pressurizing surface of the stationary die.