JPS6138856A - Surface machining - Google Patents

Abstract

PURPOSE:To perform polishing of work and surface correction of surface plate simultaneously thus to perform surface machining with high accuracy by moving the pressure plate radially to the side of low abrasion everytime when polishing predetermined number of works thereafter performing next polishing. CONSTITUTION:At first, every three works 4 are adsorbed to the underface of the plates 3A, 3B. Then they 3A, 3B are lowered to press the polishing face of work 4 againt the surface of pellet 2 with predetermined pressure. Thereafter, the surface plate 1 is rotated to perform polishing. Upon elapse of predetermined time to complete polishing, the plates 3A, 3B are lifted to remove the work 4 then new work is sucked and machined similarly. Upon reaching to predetermined number, the plate 3B is moved by predetermined distance to the side of the surface plate 1 and to repeat same polishing. Consequently, abrating amount at the side of the plate 3B will increase thus to enable control of abrating amount by means of the plate 3A.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides a flat processing method and apparatus for polishing a workpiece made of hard and brittle materials such as glass, top 2 mix, and quartz glass to obtain high flatness accuracy. Regarding.

[Prior art]

Conventionally, as this type of plane processing apparatus, those shown in FIGS. 1 and 2 are known. That is, FIG. 1 is a schematic plan view of the plane processing device, and FIG. 2 is a sectional view taken along the line II-II in FIG. A large number of diamond pellets 2 (not shown in FIG. 1) having a diameter of about 20 mmφ (not shown in FIG. 1), which are abrasive materials, are adhesively fixed at predetermined intervals (25 mm@degrees).

3A and 3B are pressure plates that respectively press a plurality of workpieces (for example, glass plates) 4 placed on the diamond pellet 2 onto the pellet 2, and these pressure plates 3A and 3B are designed so as not to interfere with each other. A rotating mechanism is provided on the shafts of the press plate 3A and 3B, and is disposed so as to be equidistant from the center 0 of the surface plate 1 in the radial direction, preferably on a straight line passing through the center 0. (not shown) rotates in the same direction as the surface plate 1. each pressure play)
A vacuum suction plate (not shown) having a large number of suction holes connected to a suction pump (not shown) is disposed on the lower surface of 3A, 3B, and the workpiece 4 is suctioned to this vacuum suction plate. There is.

The method of polishing the workpiece 4 using the flat surface Loe machine with such a configuration is as follows. First, the workpiece 4 is polished by a predetermined number of workpieces (in the figure) using the vacuum suction plates 3A and 3B (pressure plates). After suction and holding (showing the case of three pieces), these pressure plays (3A and 3B) are gradually lowered to press the workpiece 4, which is being suctioned and held, against the diamond pellet 2 with a predetermined pressing force. , the surface plate 1 is rotated at a predetermined rotation speed for a certain period of time, and the workpiece 4 is polished with a diamond pellet 2. After the polishing is completed, the pressure plates 3A and 3B are raised to their original heights to release the suction state of the polished workpiece 4. When the polishing is completed, the workpiece 4 is removed from the pressure plates 3A and 3B for one cycle. By repeating this cycle, the workpiece is continuously polished.

However, in such a conventional device, the distance from the center O of the surface plate 1 to the center of each pressure plate 3A, 3B is fixed, so as shown in FIG. (hereinafter referred to as π wear amount) differs depending on the distance from the center 0 of the surface plate 1.

In other words, assuming a model in which a workpiece 4 having a certain shape (a circle with radius RT) is polished on the surface plate 1 as shown in FIG. 4, the amount of wear on the surface plate 1 in this case is hω
(mm) is proportional to 2111 machining speed, pressure, and time, so it is expressed by the following formula.

ha+-Na+・(・,)・(lower,)royal rw),
tπ α(T,) is the contact ratio (ax-” (Cr, “-Ri+C
2)/2r, ・C)), N is the rotation speed of the surface plate, and t is time.

C is the distance from the center of the surface plate to the center of the workpiece.

RA is the radius of the surface plate, and R1 is the minimum effective polishing diameter of the surface plate.
N T Id Pressure plate rotation speed.

r(, , is the distance from the center of the surface plate to any point a on the diamond pellet.

So, now R = 400 mm, RB = 130 mm,
RT=185mm, Nω=NT=60r yP +m, and C'=250.260.270.280.290.
When calculating by substituting 300, 310, 315 into the above formula, as shown in Figure 3, the larger C becomes,
The amount of wear on diamond pellets is reduced. This is surface plate 1 and pressure plate 3A.

It is assumed that the direction of rotation of 3B is irrelevant.

As a result, the flatness accuracy of the surface plate 1 is transferred to the surface accuracy of the workpiece 40, so the amount of wear of the diamond pellets 2 near the center 0 of the surface plate 1 is greater than that of the diamond pellets 2 around the surface plate 10. However, this difference in wear amount has the disadvantage that the flatness of the workpiece 4 deteriorates.

Therefore, in the past, in order to correct the amount of wear on the diamond pellets 2, after polishing a predetermined number of workpieces 4, a correction plate (made of cast iron) having a diameter as large as the diameter of the surface plate 1 was used.
(pressure play) 3A and 3B are placed on the diamond pellet 2 and the surface plate 1 is rotated to polish the diamond pellet 2 so that the amount of polishing is uniform, but in the meantime, the workpiece Amount of polishing of object
There was a drawback that the work had to be temporarily suspended and productivity deteriorated.Before, instead of using diamond pellets, an abrasive material such as aluminum oxide was sprinkled on the surface plate to polish the workpiece. The apparatus also has the disadvantage that the same phenomenon as described above occurs, that is, the amount of wear of the surface plate itself is different between the center side and the peripheral side of the surface plate.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and its first purpose is to move the pressure plate to the side where the amount of wear of the surface plate is less in the radial direction of the surface plate every time a predetermined number of workpieces are polished. By moving the workpiece to the next polishing stage, polishing the workpiece and correcting the plane of the surface plate can be performed at the same time, making it possible to perform high-precision surface machining as well as correction work using the correction plate. The object of the present invention is to provide a flat surface machining method that is designed to improve productivity while keeping in mind the need for this.

A second object of the present invention is to maintain a high level of flatness of the surface plate by providing a pressure plate movable in the radial direction of the surface plate, thereby making it possible to perform highly accurate surface machining of the workpiece. DESCRIPTION OF THE PREFERRED EMBODIMENTS An object of the present invention is to provide a plane processing apparatus that can perform the following steps.

〔Example〕

FIGS. 5(a) and 5(b) are a longitudinal cross-sectional view and a plan view showing an embodiment of the flat processing apparatus according to the present invention. In addition,
In the figure, the same components as in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted. The difference in this figure from the conventional device shown in FIGS. 1 and 2 is that one of the pressure plates (3B) has a function to control the correction of the amount of wear on the diamond pellet 2. 3B is the other pressure play) Surface plate 1 moves closer to and away from 3A.
It is arranged to move freely in the radial direction. All other configurations are the same as the conventional device, and the distance L from the center 0 of the surface plate 1 to the center of the pressure play 3A is set to 260 mm. In addition, 10.11 is the pressure play) 3A, 3B shaft 12, 13 is the bearing, 14 is the rotation axis of the surface plate 1 (in the same figure, pressure play) 3A.

A vacuum suction plate disposed on the lower surface of the workpiece 3B for suctioning and holding the workpiece 4 is not shown.

Although the mechanism for moving the pressure play) 3B in the radial direction of the surface plate 1 is not shown in the drawings, various mechanisms such as manually or automatically moving the rotating shaft 11 using a ball screw, screw screw, etc. may be adopted. is possible.

Next, a polishing method using such a flat surface processing apparatus will be described in detail. First, the workpiece (for example, 127 mm x 127 r
Attach three glass plates (ys+n Next, the pressure plates 3A and 3B are lowered to press the main surface (polished surface) of the workpiece 4 against the surface of the diamond pellet 2 with a predetermined pressure. Next, the surface plate 1 is rotated to polish the workpiece 4. At this time, the center of surface plate 1 is 0
(pressure play) distance to center of 3B +11L
! l is set to be the same as Lm, that is, 260rnry+. When the polishing is completed after a certain period of time has elapsed, pressure plates 3A and 3B are raised to remove the workpiece 4.
After removing the workpiece and suctioning and holding a new workpiece, pressure plates 3A and 3B are lowered again to perform polishing. In this way, the workpieces are polished repeatedly, and when the number of workpieces reaches a predetermined number, the pressure plate 3B is moved a certain distance to the center 1 around the surface plate 10 to perform polishing. After polishing a predetermined number of workpieces at this moved position, the pressure plate 3B is further moved to the peripheral side of the surface plate 1 by a certain distance. The workpiece is polished by repeating these operations.

The table below shows the relationship between the number of workpieces 4 polished by the pressure plate 3B and the distance Lm of the pressure plate 3B when the number is polished 13 times.

Further, virtual planes 01, 02 . . . near the center of the surface plate 1 after polishing a predetermined number of sheets are shown. Diamond Beret 2 against O8
The relative wear amount of the two peripheral parts A and B is also shown.

The difference in the amount of wear is shown in FIG. When polishing without moving the pressure brake (pressure brake) 3B, the amount of wear on the diamond pellet 2 varies greatly depending on the distance from the center 0 of the surface plate 1, as shown in FIG. When the brake (brake) 3B is moved to the peripheral side where the amount of wear is less each time a predetermined number of sheets are polished, the amount of wear on the peripheral side caused by the plate 3B increases, and the amount of wear caused by the pressure play) 3A is controlled. As a result, there is no significant difference in the amount of wear of the diamond pellets 2 between the vicinity of the center and the periphery of the surface plate 1, and the workpiece can be polished with high precision. In addition, since the pressure play (3B) corrects wear, there is no need to use a correction plate as in the past, making continuous polishing possible and improving productivity. In the example, a total of 4080 workpieces were polished, but even when 20,000 workpieces were polished, the difference between the amount of wear near the center of the surface plate and the amount of wear around the peripheral portion of the diamond pellet 2 was within 10μ.

In addition, in the above example, two pressure plays) 3A
, 3B was used, and the pressure plate 3B was used to correct the amount of wear, but this is not limited to this, and only one pressure plate may be used. All you have to do is move it to the side with less amount. Further, the number may be three or more.

FIG. 7 is a longitudinal sectional view showing another embodiment of the present invention. 2
0.20 has a through hole 21 that accommodates the workpiece 4 and has a constant N
Pressure play with a holder placed on I) 3A
, 3B are configured to fit together. The above-mentioned diamond pellets are not fixed to the upper surface of the surface plate 1, and water mixed with aluminum oxide is sprayed as an abrasive to polish the workpiece 4. Therefore, in this case, the surface of the surface plate 1 itself wears out, but the amount of wear is controlled by pressure play (3B) every time a predetermined number of sheets are polished. It is almost uniform over the entire surface. In addition, since the movement of the workpiece 4 is restricted by the holders 20 and 20, there is no need for the pressure plates 3A and 3B to suction and hold the workpiece 4, and the structure of the brakes 3A and 3B is simplified. has been done.

In addition, although the above embodiments have all described cases in which workpieces having the same size are polished, the present invention is not limited to this, and workpieces having different sizes may be polished in each polishing process. Of course, it is possible. However, in order to easily correct the amount of wear, it is desirable that the size of the workpiece polished at one time by the two pressure plays 3A and 3B be small.

In addition, all of the above examples are pressure plays) 3A
, 3B were rotatably supported by the shaft 10.11,
Each pressure play does not necessarily require an axis)
It goes without saying that at least one pair of correction rollers may be brought into sliding contact with the river surfaces of 3A and 3B, and one of the pressure plates may be moved by the movement of the rollers themselves.
[Effects of the Invention] As explained above, according to the flat surface processing method according to the present invention, the pressure plate is moved to the surface plate or the side where the amount of wear of the diamond pellets fixed to the surface plate is less, every time a predetermined number of diamond pellets are polished. Since the amount of wear is corrected, the surface of the workpiece can be processed with high XF surface accuracy, and is suitable for manufacturing substrates such as photomask blanks used in the semiconductor industry. In addition, since the pressure plate is arranged to move freely, the structure of the device itself is simple, and there is no need for correction with a correction plate, which enables automatic continuous polishing and improves productivity. It's large.

[Brief explanation of drawings]

Figures 1 and 2 are a schematic plan view and cross-sectional view showing an example of a conventional flat surface 71111 device, Figure M3 is a diagram showing the wear amount of diamond pellets with respect to the distance from the center of the surface plate in the conventional device, and Figure 4. 5(a) and 5(b) are longitudinal cross-sectional views and plan views showing an embodiment of the flat processing apparatus according to the present invention, and FIG. 6 is a diagram for explaining the wear of diamond pellets. FIG. 7 is a longitudinal sectional view showing another embodiment of the present invention. 1... Surface plate, 2, @ fist, diamond pellet, 3
A, 3B@--pressure plate, 4--φφ workpiece, ()--center of surface plate, 20... holder.

Claims (2)

[Claims] (1) A workpiece placed on a surface plate that rotates at a constant speed is pressed against the surface plate with a pressure plate while polishing the surface of the workpiece that comes into close contact with the surface plate, and after polishing a predetermined number of surfaces. A flat surface machining method characterized in that a new workpiece is polished by moving the pressure plate in the radial direction of the surface plate to the side where the surface plate has less wear. (2) A surface plate on which a workpiece is placed and rotated at a constant speed, and a pressure plate that presses the workpiece against the surface plate, the pressure plate being movable in the radial direction of the surface plate. A plane processing device that is characterized by the following.