JPH0349856A - Surface polishing method - Google Patents

Abstract

PURPOSE:To avoid a trouble of generating sagging in an end edge so as to improve polishing accuracy by setting the thickness of a workpiece holder almost equal to the thickness of a workpiece, after it is polished, and performing polishing work to this thickness. CONSTITUTION:Of the workpiece 14 to be polished, a polished part to a thick ness equal to the thickness t1 of a workpiece holder 7 is impeded thereby with no more polishing advanced. Accordingly, the workpiece 14 is placed in a condi tion that its total surface even to an end edge is equally polished to the thick ness of the workpiece holder 7, that is, finish thickness t2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a surface polishing method applied to polishing aluminum substrates for magnetic disks and other objects to be polished.

2. Description of the Related Art In this type of surface polishing method, as shown in FIG. Elastic grindstones (102) (103) based on synthetic resin such as polyvinyl alcohol (PVA) are pressed against one or both sides of the object to be polished (100), and in this state, the object to be polished (101) and the grindstone (102) ( A method is known in which the object to be polished (100) is polished by moving one or both of the objects (101'').

Problems to be Solved by the Invention However, if the problem arises, the elastic grindstone (102) (101)
When the grinding wheel is in pressure contact with the workpiece (100), as shown in FIG.
100) and deforms into a sunken state. If polishing is performed in this state, the edge of the object to be polished (100) may be subject to diagonal pressing force, or the fine abrasive grains (104) in the grindstone that have fallen off during processing may be concentrated on the edge. Combined with this, there is a problem in that the edges are polished into an inclined or arcuate shape, resulting in so-called end face sagging (1 (15)).

This invention was made in view of the above technical background, and an object of the present invention is to obtain a polished object whose polished surface is flat all the way to the edge and has no edge sag.

Means for Solving the Problems The above object, as shown with reference to the reference numerals in the drawings, is to move the workpiece (14) held in the workpiece holder (7) to the workpiece holder (7). In a surface polishing method in which the object to be polished (14) is polished by relative movement with elastic grindstones (3) and (4) pressed against one or both sides of the object to be polished, the object to be polished (7)
The thickness (t1) of the object to be polished (14) after polishing (
This is achieved by a surface polishing method characterized in that the thickness is set to be approximately the same as t2) and polishing is performed to the desired thickness.

The thickness of the workpiece holder (7) among the workpieces (14)
The part polished to the same thickness as t1) is blocked by the object holder (7) and cannot be polished any further. Therefore, the entire surface of the object to be polished (14) up to the edge is uniformly polished to the thickness of the object to be polished (7), that is, the finished thickness (t2).

Example Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 2 and 3 show an example of a surface polishing machine embodying the present invention. In the same figure, (A) is a flat surface polishing machine, and this polishing machine has a pair of upper and lower opposed surface plates (1) and (2).
and donut-shaped upper and lower elastic grindstones (3) (4) made of a synthetic resin base such as PVA attached to the inner surface of each surface plate, and placed between each grindstone (3) (4) at the center of the axis of the grindstone. a sun gear (5), an internal gear (6) disposed concentrically outward of the sun gear (5), and an outer peripheral surface of both the sun gear (5) and the internal gear (6). and one or more thin plate spur gear-shaped object holders (7) made of fiber-reinforced plastic arranged in mesh with each other. Further, each retainer (7) is formed with a plurality of holes, into which the disk-shaped object to be polished (14) is fitted and held. Furthermore, the upper and lower surface plates (1) and (2) are the drive shafts (la) (2a) and sprockets (lb).
(2b) is connected to the first motor (11), and is rotated by the drive of the motor (11). The upper surface plate (1) is supported by a cylinder (not shown) so as to be able to move up and down, and in the lowered position shown in FIG. , a rotational force is applied in the opposite direction to that of the lower surface plate (2). On the other hand, the sun gear (5) is connected to the second motor (12) via the drive shaft (5a) and sprocket (5b), and the internal gear (6) is connected to the second motor (12) via the drive shaft (6a) and sprocket (8b). Third motor (13)
These motors (12)
(13) rotate at different rotational speeds, thereby causing the retainer (7) to rotate and revolve like an idle gear. In addition, the upper and lower surface plates (1
)(2) The rotational speeds of the sun gear (5) and the internal gear (6) are set in advance at a desired ratio so that both sides of the object to be polished (B) can be processed equally.

In the illustrated surface polishing machine, the workpiece to be polished (14) is first set in the workpiece holder (7), and then the upper and lower surface plates (1) (
2) to bring the elastic grindstones (3) and (4) into pressure contact with the object to be polished (14) with a predetermined pressure. Next, the first to third motors (11), (12), and (13) are driven to rotate the upper and lower surface plates (1), (2), the sun gear (5), and the internal gear (6).

Due to the rotation of the sun gear (5) and the internal gear (6), the workpiece holder (7) rotates and revolves around the rotation centers of the upper and lower grindstones (3) and (4), and the rotating elastic grindstone (3) )(4)
The polishing process of the object to be polished (14) is performed by the action of.

By the way, the thickness (t1) of the polishing object holder (7) is set to be approximately the same as the thickness (t2) of the polishing object (14) to be obtained by polishing, as shown in FIG. has been done. Here, "habo" means to allow a slight error. Specifically, the finished thickness (t2) of the object to be polished (14)
If the error is within about minus 100μm,
In practice, this is hardly a problem. Preferably, the error range is 50 μm or less.

/ Using the polishing object holder (7) set to a thickness of
The workpiece (14) is adjusted to its final thickness, that is, the workpiece holder (7).
) until the thickness is equal to that of the In Figure 1 (
14a) is a polishing type.

During the polishing process, the edge of the object to be polished (14) is shaved in an inclined manner to form a sag (105) as shown in FIG. When it reaches the same height as the end face of the object holder (7), the progress of polishing of that part is stopped because it is obstructed by the object holder (7), and other protruding parts are polished. Become.

In this way, the entire object to be polished (14) is held in the object holder (7).
) The polishing is finished when the thickness (t1) is reached and further polishing becomes virtually impossible.

The workpiece (14) taken out from the workpiece holder (7) has a thickness that matches the desired finished thickness (t2) as shown by the chain line in FIG. 1, and reaches the edge. The result is a flat polished surface with no sag. Note that (31) and (41) in FIG. 1 are abrasive grains in the grindstone.

By the way, using the plane polishing apparatus shown in Fig. 2, as shown in Fig. 5, the diameter is 3.5 inches and the finished thickness (t2) is 1.
．． 250am magnetic disk aluminum substrate (14
) was held in a polishing object holder (7') with a thickness (tl') of 1.000 to 1.100 m and polished, an arc-shaped sag (15) occurred on the periphery of the substrate. did.

In order to judge the extent of this sag (15), the substrate (14
) and the distance from it to the center of the board (ρ)
Connect the positions of 5711111 with a line and draw a sag (1
When I measured the distance (h') to 4), it was 0.200
μm to 0.300 μm.

On the other hand, as shown in Fig. 4, the same aluminum substrate (14) was held in a polishing object holder (7) with a thickness (t1) of 1.250 mm and polished. The distance (h) to the sag was measured in the same way and was 0.100.
μm or less, and a good polished surface without sagging to the edges was obtained.

As described in detail, the present invention provides for grinding a workpiece held in a workpiece holder by relative movement between the workpiece holder and an elastic grindstone pressed against one or both sides of the workpiece. In the surface polishing method, the thickness of the object holder is
It is characterized in that the thickness is set to be approximately the same as the thickness of the object to be polished after polishing, and the polishing process is performed until the thickness reaches the set thickness. For this reason, the part of the workpiece that has been polished to the same thickness as the workpiece holder is blocked by the workpiece holder and polishing no longer progresses, so that the entire surface of the workpiece is polished. The object to be polished is polished to the thickness of the holder, that is, the finished thickness, all the way to the edge. As a result, it is possible to avoid the inconvenience of sagging at the edges, and it is possible to provide a high-quality polished object with high processing accuracy.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the dimensional relationship between the workpiece to be polished and the workpiece holder with the grindstone pressed against it before polishing, and FIG. 2 is a partial front cross-sectional view of a surface polishing machine embodying the present invention.
3 is a perspective view of the main parts showing the use state of the polishing machine shown in FIG. 2, FIG. Figure 5 is a cross-sectional view of main parts showing the workpiece and workpiece holder after polishing using the conventional method, and Figure 6 shows the grindstone and workpiece when polishing was performed using the conventional method. FIG. 3 is a cross-sectional view showing the relationship between a polishing object and a polishing object holder. (3) (4)... Elastic grindstone, (7)... Object holder, (14)... Object to be polished. Above Figure 4 Figure 6

Claims (1)

[Claims] The workpiece (14) held in the workpiece holder (7) is
In a surface polishing method for polishing by relative movement between the workpiece holder (7) and elastic grindstones (3) and (4) pressed against one or both sides of the workpiece (14), the workpiece holder ( 7) A surface polishing method characterized in that the thickness (t_1) is set to be approximately the same as the thickness (t_2) of the object to be polished (14) after polishing, and the polishing process is performed to this thickness.