JPH08229796A - Polishing plate - Google Patents

Abstract

PURPOSE: To provide a polishing plate for an optical element and for a molding metal die with curvature adjustable. CONSTITUTION: An adjusting part 20 is constituted by a bolt 22 fixed to a holding part 14, spring 24 and a nut 26. The spring 24 is mounted to be compressed, and force can be given to an end part 12b of a polishing part 1 from the holding part 14 by repulsive force of this spring 24. The nut 26 is rotated to change its position in a point end of the bolt 22, and a compression amount of the spring is changed, so that a level of tension can be adjusted. By the adjusting part 20, when force is applied to the polishing part 12 from the holding part 14, the polishing part 12 is deformed with a fixed part 16 serving as the support point, to change a transcription surface 12a in a direction of increasing its curvature R in the polishing part 12. The curvature can be changed by a mechanism thus simplified and further quickly. In order to change the polishing part 12 in a direction of decreasing the curvature R, reversely pulling force to a side of the holding part 14 is given to the end part 12b of the polishing part 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element such as a lens and a mirror and a polishing dish used for polishing a molding die for the optical element.

[0002]

2. Description of the Related Art The structure of a conventional polishing device for polishing an object to be processed such as an optical element and a molding die thereof will be described with reference to FIG. This device includes a holder 2 for holding a work piece 1.
And a polishing dish 3 having a transfer surface 3a having a finish shape curvature R of the workpiece, and the workpiece 1 and the holder 2 are pressed against the polishing dish 3 and shaken along the transfer surface 3 of the polishing dish 3. It is composed of a moving kanzashi 4. The holder 2 also plays a role of a guide when swinging. In the conventional apparatus configured as described above, the transfer surface 3a of the polishing dish 3 is relatively oscillated by pressure on the processing surface 1a of the workpiece 1, thereby polishing the processing surface 1a and removing the processing surface 1a. The shape has the same curvature R as the transfer surface 3a.
To finish.

[0003]

However, in reality, it is difficult to accurately match the curvature R of the transfer surface 3a of the polishing dish 3 with the curvature R'of the target shape. Further, since the work piece 1 and the polishing dish 3 are slag-working, the shape of the transfer surface 3a of the polishing dish 3 changes as the working progresses, and thus the shape of the work surface 1a of the work piece 1 also becomes the target shape. Will change. In particular, the pre-processing shape curvature R ″ of the workpiece 1 and the polishing dish 3
The curvature changes due to the disagreement with the curvature R of the transfer surface 3a. When R ″> R≈R ′, the curvature R of the transfer surface 3a changes in the direction of increasing, so that the curvature of the finish becomes larger than the target curvature. On the contrary, when R ″ <R≈R ′, the finished curvature becomes smaller than the target curvature.

For this reason, it is necessary to constantly manage the curvature of the processed surface 1a of the work piece 1 and the transfer surface 3a of the polishing dish 3 and correct the curvature. This correction processing is performed by the experience of the operator and requires time and skill to adjust it repeatedly. Further, when the workpiece is a molding die, it is necessary to correct the curvature of the molding die according to the shrinkage of the product during molding. Since the shrinkage varies depending on the product material, the product shape, and the molding conditions, an operation of correcting the curvature R of the transfer surface 3a of the polishing dish 3 occurs each time these changes. However, this requires a new processing of the transfer surface 3a of the polishing dish 3, which is time-consuming and expensive.

Therefore, Japanese Utility Model Laid-Open No. 5-60762 proposes a polishing dish in which a curvature is corrected by providing a piezoelectric element between the support of the polishing dish and the polishing layer. However, this polishing dish has a problem that a large number of piezoelectric elements are required to correct the curvature of a wide area and the mechanism becomes complicated and expensive. Further, since the characteristics of the piezoelectric element drift due to the temperature change, the curvature changes due to the temperature rise during the polishing process. Furthermore, there is a problem that the curvature correction is not smooth and is corrected to a polygonal shape. Then, this invention makes it a subject to provide the polishing dish which can correct a curvature quickly with a simple mechanism.

[0006]

In order to solve the above-mentioned problems, a polishing dish according to a first aspect of the present invention is a polishing dish which is oscillated under pressure with respect to a work surface of a workpiece to polish the workpiece. And a polishing unit for polishing and polishing, a holding unit for pressing and holding the polishing unit, a fixing unit for connecting and fixing the polishing unit and the holding unit, and an adjustment for applying force from the holding unit to the polishing unit so that the polishing unit is deformed. It is characterized by having a section. A second aspect of the invention is characterized in that, in the polishing dish according to the first aspect of the invention, the gap size between the holding part and the polishing part is measured, and the magnitude of the force of the adjusting part is controlled by the value of the measured gap size. And

A third aspect of the invention is a polishing dish according to the first aspect of the invention, wherein an adjusting tool having an arbitrary thickness is sandwiched between the polishing part and the holding part, whereby the force between the polishing part and the holding part is reduced. It is characterized by adjusting the gap size. A fourth aspect of the present invention is the polishing dish according to the third aspect of the present invention, wherein in the adjusting section, the adjusting tool having a thickness changed with respect to the curvature direction of the polishing dish is moved in the curvature direction so as to move between the polishing section and the holding section. It is characterized by controlling the force and the gap size. A fifth aspect of the present invention is the polishing dish according to the first aspect of the present invention, including a control unit that pressurizes the force of the adjusting unit by liquid pressure to change the magnitude of the liquid pressure. A sixth invention is characterized in that, in the polishing dish according to the first invention, the second moment of area of the polishing portion is changed.

[0008]

According to the polishing dish of the first aspect of the present invention, the curvature can be corrected quickly with a simple mechanism by applying a force to the polishing section from the adjusting section to deform the polishing section. According to the second aspect of the present invention, the magnitude of the force is controlled by the actual degree of deformation of the polishing section due to the force from the adjusting section, so that highly accurate and stable curvature correction can be performed.
According to the third and fourth aspects of the invention, the amount of deformation of the polishing portion is directly controlled not by the magnitude of the force but by the size of the gap between the holding portion and the polishing portion, so the curvature can be corrected accurately.

According to the fifth aspect of the present invention, by controlling the liquid pressure, the curvature can be corrected uniformly with a simpler mechanism and a smaller space. According to the sixth aspect, the amount of deformation of the polishing portion with respect to the direction of curvature can be brought close to the target amount of shape deformation when the curvature is changed, and the curvature can be corrected accurately.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a sectional view of a polishing dish during polishing according to the present invention, and FIG. 2 is a diagram when a force is applied to the polishing section from an adjusting section to deform the polishing section and correct the curvature. The workpiece 1 is held by the holder 2 such that the processing surface 1a is in contact with the transfer surface 12a of the polishing dish 10, and is pressed and rocked by the hammer 4 to be polished.

The polishing dish 10 includes a polishing section 12 having a transfer surface 12a and a holding section 14 for holding the polishing section 12 under pressure.
A fixing part 16 for connecting and fixing the polishing part 12 and the holding part 14, and an adjusting part 20 for applying a load from the holding part 14 to the polishing part 12 so that the polishing part 12 is deformed. The adjusting unit 20 includes a bolt 22 fixed to the holding unit 14.
, A spring 24 attached to the tip of the bolt 22, and a nut 26. The spring 24 is compressed and attached, and the repulsive force of the spring 24 causes the holding portion 1 to move.
It is possible to apply a force from 4 to the end portion 12b of the polishing portion 12. By rotating the nut 26 to change the position of the nut 26 at the tip of the bolt 22 and change the compression amount of the spring, the magnitude of the force can be adjusted.

When a force is applied to the polishing section 12 from the holding section 14 by the adjusting section 20, the polishing section 12 is deformed around the fixed section 16 as a fulcrum, and the curvature R of the transfer surface 12a of the polishing section 12 is changed to increase. To do. With such a simple mechanism, the curvature can be corrected quickly. In order to deform the polishing portion 12 in the direction in which the curvature R decreases, conversely, a force pulling toward the holding portion 14 side may be applied to the end portion 12b of the polishing portion 12. Further, the fixing portion 1 is attached to both end portions 12b of the polishing portion 12.
6, the fixed portion 16 and the polishing portion 12 may be rotatably supported, and the adjusting portion 20 may be provided at the center of the polishing portion 12.

Although the accuracy of curvature required for the optical element and the magnitude of the required curvature correction value differ depending on the type, generally, the curvature accuracy is ± several tens μm and the curvature correction value is several hundreds μm. For example, the curvature of the cylindrical surface is 100.0 mm
To 99.9 mm, the displacement Δ is about 15 μm in the polishing dish with L = 50 mm. On the other hand, in order to displace the polishing part by about 15 μm, if the material of the polishing part is cast iron (elastic modulus E = about 98 GPa) and the thickness b = 5 mm,
A force of about 0.4 N / mm (about 40 g / mm) may be applied per unit length.

FIG. 3 is an explanatory diagram showing a second embodiment of the present invention. The polishing dish 10A includes a holding portion 14 and a transfer surface 12a.
And a holding part 14 supports the polishing part 12 via a fixing part 16. The adjusting portion has the bolt 22 similar to that shown in the first embodiment, and the spring 24 is arranged at the tip of the bolt 22. A nut 26 screwed onto the bolt 22 adjusts the compression amount of the spring 24. Nut 26
The outer peripheral surface of is formed in a gear shape. The stepping motor 30 attached to the holding portion 14 has a motor shaft 34
The gear 36 is attached to the. This gear 36 is nut 2
It meshes with the 6th gear.

Therefore, by sending a pulse signal to the stepping motor 30, the nut 26 is rotated by a predetermined rotation angle and the compression amount of the spring 24 is adjusted to adjust the curvature R of the polishing portion 12.
Can be changed. The measuring unit 40 attached to the holding unit 14 uses, for example, the light beam 40a to polish the polishing unit 1.
The gap size between the two ends 12b is detected to achieve highly accurate adjustment. As the structure of the adjusting portion, instead of the nut and the spring, an adjusting tool having an arbitrary thickness may be sandwiched between the polishing portion and the holding portion.

FIG. 4 is an explanatory view showing a third embodiment of the present invention. The polishing dish 10B includes a holding unit 14 and a polishing unit 12 having a transfer surface 12a, and the holding unit 14 supports the polishing unit 12 via a fixing unit 16. The stepping motor 50 attached to the holding portion 14 drives the ball screw 52 to rotate. The slider 54 screwed onto the ball screw 52 slides in the axis X direction by the rotation of the ball screw 52. The upper surface of the slider 54 is formed as a tapered surface 56. Therefore, by adjusting the position of the slider 54 via the stepping motor 50, the curvature R can be adjusted by elastically deforming the end 12b of the polishing section 12.

5 and 6 are explanatory views showing a fourth embodiment of the present invention. The polishing dish 10C includes a holding portion 14 and a transfer surface 1.
2a is provided, and the holding portion 14 is the fixed portion 1.
The polishing part 12 is supported via 6. A groove 14a is provided at a position facing both ends 12b of the polishing section 12 of the holding section 14, and an elongated bag-shaped elastic member 60 is arranged in the groove 14a. This elastic member 60 is
It is connected to a liquid supply source via 2a and 62b. Therefore, the elastic member 60 that press-fits the liquid into the elastic member 60 through the injection ports 62a and 62b expands, and elastically deforms both end portions 12b of the polishing portion 12. The liquid pressure is controlled by a control unit (not shown). As a result, a uniform force can be applied to any part of the polishing dish 10C, and the force can be kept constant without being affected by the deformation of the polishing portion 12.

7 and 8 show a fifth embodiment of the present invention. FIG. 7 is a sectional view of the polishing dish, and FIG. 8 is a diagram of a deformation amount curve in the polishing dish. The polishing section 12 of the polishing dish 10D is
The thickness b becomes smaller toward both ends 12e. As a result, the second moment of area I at each value of the polishing section 12 is X =
If 0 and the end is X = L, the value changes in proportion to LX. FIG. 8 shows an example of the deformation amount curve when L = 50 mm. At this time, the amount of deformation Δ can be brought closer to the target amount of deformation when the curvature is changed more than in the case of a polishing dish in which the thickness of the polishing portion 12 is constant, that is, the second moment of area I is constant. The curvature can be corrected well.

[0019]

As described above, according to the first aspect of the present invention, since the adjusting portion for applying a force to the polishing portion to deform the polishing portion is provided, the curvature can be corrected simply by a mechanism. There is an effect that can be. According to the second aspect of the present invention, the magnitude of the force is controlled according to the actual degree of deformation of the polishing section due to the force from the adjusting section, so that it is possible to perform highly accurate and stable curvature correction. .

According to the third and fourth aspects of the invention, the amount of deformation of the polishing portion is directly controlled by the size of the gap between the holding portion and the polishing portion instead of the magnitude of the force, so that the curvature is corrected accurately. There is an effect that can be. According to the fifth invention, since the adjusting portion for deforming the polishing portion by the liquid pressure is provided, there is an effect that the curvature can be corrected uniformly with a simpler mechanism and space saving. According to the sixth aspect, since the second moment of area of the polishing portion is changed with respect to the curvature direction, it is possible to bring the deformation amount of the polishing portion close to the target shape deformation amount when the curvature is changed. The effect that the curvature can be corrected well is exhibited.

[Brief description of drawings]

FIG. 1 is a sectional view of a polishing dish during polishing according to a first embodiment of the present invention.

FIG. 2 is a view when a force is applied to the polishing section according to the first embodiment of the present invention from the adjusting section to deform the polishing section and correct the curvature.

FIG. 3 is a sectional view of a polishing dish according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a polishing dish according to a third embodiment of the present invention.

FIG. 5 is an overall view of a polishing dish having a cylindrical surface shape according to Example 4 of the present invention.

FIG. 6 is a sectional view of a polishing dish according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view of a polishing dish according to a fifth embodiment of the present invention.

FIG. 8 is a diagram of a deformation amount curve of a polishing dish according to a fifth embodiment of the present invention.

FIG. 9 is a front view of a conventional device.

[Explanation of symbols]

1 Workpiece, 2 Holder, 3 Polishing Plate, 3a
Transfer surface, 4 Kanzashi, 10, 10A, 10B, 1
0C, 10D polishing dish, 12 polishing part, 14 holding part, 16 fixing part, 20 adjusting part.

Claims (6)

[Claims] 1. In a polishing dish for polishing by swinging under pressure with respect to a work surface of a workpiece, a polishing section for contacting and polishing the workpiece, a holding section for holding the polishing section under pressure, and a polishing section. A polishing dish, comprising: a fixing part that connects and fixes the holding part and the holding part; and an adjusting part that applies a force from the holding part to the polishing part so that the polishing part is deformed. 2. The polishing dish according to claim 1, wherein the size of the gap between the holding part and the polishing part is measured, and the magnitude of the force of the adjusting part is controlled by the value of the measured gap size. 3. In the adjusting section, an adjusting tool having an arbitrary thickness is sandwiched between the polishing section and the holding section to adjust the force and the gap size between the polishing section and the holding section. The polishing dish according to claim 1, which is characterized in that. 4. The adjusting unit controls the force and the gap size between the polishing unit and the holding unit by moving the adjusting tool whose thickness has changed in the curvature direction of the polishing dish in the curvature direction. The polishing dish according to claim 3, which is characterized in that. 5. The polishing dish according to claim 1, further comprising a control unit that pressurizes the force of the adjusting unit by a liquid pressure to change the magnitude of the liquid pressure. 6. The polishing dish according to claim 1, wherein the second moment of area of the polishing portion is changed.