JPS6071160A - Method of working mirror surface of disk-like workpiece - Google Patents

Abstract

PURPOSE:To polish an aluminum workpiece to provide a high quality mirror surface in working the mirror surface of a magnetic disk for a computer by setting the relationship between the relative moving speed of abrasives, the rotational frequency of the workpiece and the outer peripheral dimension of the abrasives to a specified value or less. CONSTITUTION:In working a disk-like workpiece 1 of aluminum, the workpiece 1 is rotated by a jig 2, while abrasives 5 are pressed against both surfaces of the workpiece 1 with a predetermined press pressure and working liquid 7 is supplied from a supply path 6 through the abrasives 5 to the surface of the workpiece 1. Then abrasives 5 together with a holder 3 is moved in one direction or reciprocating direction vertically and circumferentially to the rotation of the jig 2. The working liquid 7 having a function of restraining the oxidation of aluminum surface has 60dyne or less/cm of surface tension, and the abrasives 5 used are of #1,500-#8,000 of grain size. And the relationship between the relative moving speed Vmm./mm. of the abrasives 5 to the workpiece 1, the rotational frequency Nrpm of the workpiece 1 and the outer peripheral dimension Hmm. of the abrasives 5 is set to V/(NH)<0.015.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for mirror-finishing a disc-shaped workpiece made of an aluminum material such as aluminum or its alloy using a machining fluid and an abrasive.
The purpose is to achieve a mirror finish of Rmax or less.

In general, disk-shaped workpieces such as magnetic disks for computers require a high degree of shape accuracy and mirror-finished surfaces in order to increase the density of recorded information, and high production efficiency is required in order to reduce production costs. desired.

By the way, one of the conventional production methods is the high-precision turning method using a diamond cutting tool, which produces high-quality workpieces, but the problem with this method is that it increases the scale of the equipment and reduces productivity. It is low.

Precision grinding using a rigid grinding wheel is also an example of a method that is used, but even with this method, a sufficient finished surface cannot be obtained due to grinding, etc., and ensuring the accuracy of the equipment is a problem. Become.

On the other hand, for aluminum materials such as aluminum and its alloys with a surface tension of 60 d3'n/m or less, a method of mirror-finishing aluminum materials using a machining fluid that has a surface oxidation suppressing function and an abrasive material that is water permeable. was invented by the present inventors (
(Japanese Patent Application No. 58-86441), and according to this method, a high-quality mirror surface can be stably obtained with less clogging of the abrasive material. Affected by abrasion conditions.

This invention was made with the above points in mind, and
Water-permeable abrasives are arranged at symmetrical positions on both sides of a rotating disk-shaped workpiece made of aluminum material, and while pressing both abrasives against both sides of the workpiece, the abrasives are perpendicular to the rotation axis of the workpiece. In a mirror finishing method for a disc-shaped workpiece that is machined by moving it in the direction, the surface tension is 60 dyn/crn.
In the following, using a machining liquid that has the function of suppressing surface oxidation of aluminum material and an abrasive material with an abrasive grain size of 1500 to #8000, the relative moving speed V (Mg 7 m) of the abrasive material with respect to the workpiece, and the rotation of the workpiece. A disk-shaped workpiece characterized in that the relationship between the number N Cr 1)Ill :) and the dimension 1(, wa) of the abrasive material in the outer circumferential direction of the workpiece is set to V/(NH) (0,015). This provides a method for mirror-finishing objects.

Therefore, according to the invention, the efficiency is <01pm R
A mirror surface of less than max can be obtained.

Finally, this invention, together with drawings showing its embodiments,
Explain in detail.

First, the machining of a disc-shaped workpiece will be explained with reference to FIG.

In the figure, (1) is a disc-shaped workpiece made of aluminum held by a rotating jig (2), (3) is a holder whose tip has a U-shaped cross section, and (4) is a holder (C). 3) is a pressing tool attached to the left and right inner surfaces of the tip, and (5) is a pressing tool attached to both sides (4).
) is a water-permeable flexible abrasive material containing abrasive grains, and both abrasive materials (5) are placed in symmetrical positions, and the abrasive grain size is 500 to 8,000. (6) are the machining fluid (7) supply holes formed by penetrating the tip end of the holder (3) and the pressing tool (4), respectively;
7) has a surface tension of 60 dy11/cm or less and has a function of suppressing surface oxidation of aluminum material.

During machining, the workpiece (1) is moved by the jig (2).
At the same time, the abrasive material (5) placed symmetrically on both sides of the workpiece (1) is pressed with a predetermined pressing pressure, and the machining fluid (7) is passed through the abrasive material (5) from the supply path (6). The abrasive material (5) is supplied to the surface of the workpiece (1) and moved together with the holder (3) in a direction perpendicular to the rotation axis of the jig (2) and in one direction or in a reciprocating direction in the outer circumferential direction.

FIG. 2 is an enlarged front view of a part of FIG. 1, and shows an abrasive material (
5) and an example of the shape and feed of the pressing tool (4) are shown.

Figure 3 shows the abrasive grain size in the abrasive material "1500 to #8000"
The relationship between the roughness (■) and the ratio V/N is summarized using the ratio V/N of the relative movement speed V indicating the abrasive grain rubbing movement and the rotational speed N of the disc-shaped workpiece (1) with AlE. Here, the dimensions of the abrasive material (5) in the circumferential direction of the crop (1) ■1
It can be seen that the dependence of the roughness R on the dimension H is reduced. This dimension H determines the number of abrasive grains applied to the workpiece (1). Note that the roughness of the base surface of the workpiece (1) is 0.2 to 0.4 μn1 n1aX.

Therefore, in order to explain the roughness generation mechanism after machining, the relationship between the abrasive material dimension H, the rotational speed N of the workpiece, and the relative movement speed of the abrasive material is summarized as V/(NH).
As shown in the figure, a relationship is obtained in which each machining condition determines the machined surface roughness R.

According to this FIG. 4, in a disc workpiece made of aluminum or its alloy material, a mirror surface of less than 0.1 mm L + aX can be obtained by V/(NH) i, ■/(■) < 0.015 f Al.

[Brief explanation of drawings]

The drawings show an embodiment of the mirror polishing method for a disc-shaped workpiece according to the present invention, and FIGS. 1(a) and (11) are a front view and a partially cutaway plan view, and FIG. 2 is a partial view of FIG. 1. The enlarged front view, FIG. 3, shows the ratio of relative movement speed V to rotational speed N, V7N. Figure 4 shows the relationship between the roughness and the ratio v/(Nl()) and the roughness of 1. Figure 1 (a) (b) Figure 2 Figure 3 Figure 4 Figure 0.002 0.0050.01 0.02 0.05
0.1υ1. ,, ,.

Claims (1)

[Claims] ■ Water-permeable abrasives are arranged at symmetrical positions on both sides of a rotating disc-shaped workpiece made of aluminum material, and the workpiece is pressed while pressing both of the abrasives against both sides of the workpiece. In a mirror finishing method for a disc-shaped workpiece, which is machined by moving the workpiece in a direction perpendicular to the rotation axis, the surface tension is 60 dyn/σ.
In the following, using a machining liquid that has the function of suppressing surface oxidation of aluminum material and an abrasive material with an abrasive grain size of 1500 to 500, the relative movement speed V (all, z
mt: ], the rotational speed N [rpH] of the workpiece, and the dimension of the abrasive material in the outer circumferential direction of the workpiece ■ [related]: V / (Nf () < 0.015. A mirror finishing method for a disc-shaped workpiece, which is characterized by: