JPS61182753A - Polishing plate - Google Patents

Abstract

PURPOSE:To perform high accurate polishing with no generation of a step difference in a workpiece to be polished, by changing a proportion of an effective contact surface with the workpiece in the diametric direction. CONSTITUTION:A polishing pad 1 is spirally placed existing on a supporter 2. And said pad 1, arranging the line width of its spiral line gradually narrower from the center part to the peripheral part, forms a distance between the neighboring lines almost to a fixed value. And the pad forms a portion between the spiral lines to a groove 3 of fixed width. As a result, an effective contact surface of the polishing pad with a workpiece to be polished provides a narrower area as the surface changes its position toward the peripheral part. That is, an effective contact area with the workpiece per unit area of a polishing plate gradually decreases from the center part to the peripheral part. Accordingly, the more in the center part is the polishing pad a contact time with the polishing pad is the longer, while the more in the peripheral part the contact time is the shorter. Consequently, correction polishing, planing a ring belt shaped convex part, can be well performed with no generation of a step difference because a polishing quantity is almost in proportion to said contact time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polishing plate, and particularly to a polishing plate suitable for polishing optical elements with high precision.

[Conventional technology]

Conventionally, in order to finish the surface of optical elements such as lenses, grisms, or reflectors to extremely high precision, the surface, which has been polished to a certain degree of precision, is partially corrected and polished using a small-diameter polishing plate. It will be done.

FIG. 7 is a schematic perspective view for explaining a specific example of such corrective polishing. In the figure, reference numeral 12 denotes an optical glass parallel flat plate which is an object to be polished, and the object to be polished 12 is circular. The object to be polished 12 is fixedly supported by bonding its lower surface to a support 14 . The support 14 is rotatable about an axis X, and the object 12 to be polished is fixed to the support 14 so as to be rotationally symmetrical about the axis X. The upper surface of the object to be polished 12 has been mirror-polished in advance by pre-processing. However, it is assumed that the illustrated ring zone Y has become convex due to this pre-processing.

In the correction polishing, a polishing plate 15 that is smaller than the size of the object 12 to be polished is used. The polishing plate 15 consists of a polishing plate 16 fixedly supported by adhering it to a support 18, and one end of a rod 20 is abutted against a recess formed in the center of the upper surface of the support 18. There is. The rod 20 is swingable in the radial direction of the object 12 to be polished by an appropriate width. 22 is a polishing liquid supply means.

While supplying the polishing liquid onto the upper surface of the object to be polished 12 from the polishing liquid supply means 22, the support body 14 is rotated in the direction of arrow A,
At the same time, corrective polishing is performed by swinging the support 18 in the direction of arrow B.

[Problem that the invention seeks to solve]

However, in conventional corrective polishing, the polishing process is performed while the polishing plate 16 of the polishing plate 15 contacts the object 12 with uniform pressure over the entire surface, so corrective polishing is performed on the upper surface of the object 12. There was a problem in that a difference in level was likely to occur between the receiving part and the non-receiving part.

FIGS. 8(a) and 8(b) are cross-sectional views of the object to be polished 12 corresponding to the section 1--2 in FIG.

Figure 8 (,) shows the state before corrective polishing, and Figure 8 (b)
2 shows the state after the corrective polishing, and as can be seen from the figure, a considerably large step 24 is formed in a position corresponding to the swing width of the polishing plate 15 during the corrective polishing.

In this case, the swing width of the polishing plate 15 is not fixed,
It has been proposed to prevent the occurrence of steps by gradually changing the swing width. However, such a mechanism for continuously changing the oscillation width is quite complicated and has the disadvantage that the polishing device becomes expensive.

[Failure to solve the problem]

According to the present invention, as a solution to the problems of the prior art as described above, there is provided a polishing plate characterized in that the ratio of the effective contact surface with the object to be polished changes in the radial direction. .

〔Example〕

Hereinafter, specific embodiments of the polishing plate of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic plan view showing a first embodiment of the polishing plate of the present invention, and FIG. 2 is a cross-sectional view taken along the line -■.

The polishing plate of this embodiment consists of a polishing pad 1 having a uniform thickness and its support 2. The polishing plate has a disk-like shape as a whole, and 2 is its axis of symmetry. The polishing A/rud is present in a spiral shape on the support 2, as shown in FIG. The width of the spiral line of the polishing nozzle 1 gradually becomes narrower from the center to the outer periphery.

The spacing between adjacent spiral lines is approximately constant. As shown in FIG. 2, the surface of the support 2 on the side to which the polishing pad is attached is smooth except for the part where the polishing pad 1 is actually attached (i.e., the area between the spiral lines).・Groove 3 with a constant width in the shape of the armpit
is formed.

In the polishing plate of this embodiment, the polishing pad 1 is uniformly pasted on the entire surface of the support 2 having a flat polishing pad pasting surface, and then cutting is performed using a numerically controlled lathe to form the polishing pad and the support at predetermined portions. It can be manufactured by removing the body surface.

In the polishing plate of this embodiment, the polishing/grid surface that effectively contacts the object to be polished has a narrow outer peripheral area.

That is, the effective contact area of the polishing plate with the object to be polished per unit area becomes gradually smaller from the center to the outer periphery of the polishing plate. Therefore, when polishing is performed using the polishing plate of this embodiment, the region of the surface of the object to be polished that comes into contact with the polishing plate has contact time characteristics with the polishing pad as shown in FIG. That is, among the contact areas with the polishing pad, the center portion has a longer contact time with the polishing pad, and the outer peripheral portion has a shorter contact time with the polishing pad.

FIGS. 4(a) and 4(b) are cross-sectional views showing changes in the object to be polished 12 when corrective polishing is performed using the polishing plate of this embodiment. Figure 4 (,) shows the state before corrective polishing;
Figure (b) shows the state after corrective polishing. According to the polishing plate of this embodiment, the contact time characteristics as shown in FIG. 3 can be obtained, and since the amount of polishing is approximately proportional to this contact time,
Correction polishing for flattening the annular convex portion can be performed satisfactorily without creating a step.

In this embodiment, the width of the spiral lines of the polishing pad 1 is gradually narrowed from the center to the outer periphery, and the interval between the spiral lines is approximately constant. The distance between the spiral lines of the polishing pad 1 may be made gradually wider from the center to the outer periphery.
Characteristics similar to those shown in the figure can be obtained.

FIG. 5 is a schematic plan view showing a second embodiment of the polishing plate of the present invention, and FIG. 6 is a sectional view taken along the line 1--2.

The polishing plate of this embodiment differs from the first embodiment only in that the polishing pad 1 is disposed concentrically on the support 2. The line width of the concentric lines of the polishing pad 1 gradually becomes narrower from the center to the outer periphery, and the intervals between the concentric lines are approximately constant.

The polishing plate of this example also has characteristics similar to those shown in FIG. 3.

In this embodiment, the width of the concentric lines of the polishing pad 1 is gradually narrowed from the center to the outer periphery, and the intervals between the concentric lines are approximately constant; however, It is also possible to make the line widths of the plurality of concentric lines of the polishing pad 1 substantially constant and the intervals between the concentric lines gradually widen from the center to the outer periphery. Similar properties are obtained.

Although the above embodiments have been explained by taking corrective polishing as an example, it goes without saying that the polishing plate of the present invention can also be used for other ordinary polishing.

Furthermore, the polishing plate of the present invention can also be used for creating and polishing an axially symmetric aspherical surface with a small amount of aspherical surface by appropriately setting the polishing time in the usage method described in the above embodiment. .

Furthermore, although a flat polishing plate was shown in the above embodiments,
Of course, convex polishing plates and concave polishing plates have similar effects.

〔Effect of the invention〕

According to the polishing plate of the present invention as described above, highly accurate polishing can be performed without creating a step on the object to be polished, without using a polishing device having a complicated mechanism.

[Brief explanation of drawings]

Figure 1 is a plan view of the polishing plate of the present invention, and Figure 2 is a plan view of the polishing plate.
−■ It is a sectional view. FIG. 3 is a graph showing the contact time characteristics between the polishing tool and the object to be polished. Figure 4 (&) and (b), and Figure 8 (a) and (
b) is a sectional view of the object to be polished. FIG. 5 is a plan view of the polishing plate of the present invention, and FIG. 6 is a cross-sectional view taken along the line -■. FIG. 7 is a perspective view showing the polishing method. 1: Polishing No.4 Rad, 2: Support, 3: Groove.

Claims (3)

[Claims] (1) A polishing plate characterized in that the ratio of the effective contact surface with the object to be polished changes in the radial direction. (2) The shape of the effective contact surface is a spiral or concentric circle, and the line width of the spiral or concentric line becomes gradually narrower from the center to the outer periphery, and The polishing plate of claim 1, wherein the spacing between the lines is substantially constant. (3) The shape of the effective contact surface is spiral or concentric, the line width of the spiral or concentric lines is approximately constant, and the distance between the spiral or concentric lines is from the center. The polishing plate according to claim 1, wherein the polishing plate gradually becomes wider toward the outer periphery.