JPH1199454A - Polishing device and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent nonuniformity of polishing quantity on a marginal part, etc., of a work small in a radius of curvature. SOLUTION: Feeding of a work W1 of a toric mold, etc., in the X, Y axial direction is carried out by oscillating a work holding base 20 to hold the work W1 around a Y axis by an X oscillating mechanism 30 and oscillating the X oscillating mechanism 30 around an X axis by an Y oscillating mechanism 40. It is possible to maintain a pressure direction of a polishing tool 10 vertical against a working surface of the work W1 even at a marginal part of the work W1 and to make polishing quantity constant by matching a center of such oscillating motion with a center of curvature or approximate curvature of a mother line direction and a child line direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus and a polishing method for polishing a curved work surface having a curvature or an approximate curvature different from each other in two orthogonal directions such as a toric shape. is there.

[0002]

2. Description of the Related Art For example, when manufacturing a mold (a toric mold) for a toric lens or the like, after a diamond precision cutting process or the like, a curved surface having different curvatures or approximate curvatures in directions of two orthogonal axes. A step of polishing the processed surface to a mirror surface is required. As a polishing apparatus used in such a case, a polishing apparatus shown in FIG. 9 has been conventionally used. This presses the polishing tool 101 to the processed surface of the workpiece W ₀ toric mold etc., work direction radius of curvature of the surface to be processed of the workpiece W ₀ is the maximum (hereinafter, referred to as. "Generatrix direction") to a feed in the Y-axis direction for moving the W _0, the direction of curvature radius of the surface to be processed of the workpiece W ₀ is the minimum (hereinafter referred to as "sagittal direction".) the polishing tool 101 is moved in the X-axis direction feed The work W ₀ and the polishing tool 101 are rubbed together.

[0003] X-axis direction of the feed of the grinding tool 101, the hairpins 102 tip is a pin joint for pressing the polishing tool 101 to the processed surface of the workpiece W _0, X-axis direction by the X stage straight driving (not shown) Is carried out. Further, Y-axis direction of feed of the workpiece W ₀ is the workpiece holding table for holding a workpiece W _0, is performed by moving the Y-axis direction by the linear driving of the Y stage (not shown).

[0004] Typically, the workpiece W by sending a workpiece W ₀ while swinging the polishing tool 101 in the sagittal direction in the generatrix direction
_The step of polishing the _0- processed surface into a band shape is repeated.

[0005]

However, according to the above-mentioned prior art, the polishing tool pressed against the work surface of the work by the kansashi can freely tilt in any direction following the inclination of the work surface. However, if the radius of curvature of the work surface is small in both the sagittal direction and the generatrix direction and the inclination of the work surface is large, when the polishing tool moves to the peripheral portion of the work, The polishing tool tilts greatly.
For this reason, the polishing load on the peripheral portion of the work is reduced,
As a result, there is an unsolved problem that the polishing amount is locally reduced and uniform polishing cannot be performed.

More specifically, as shown in FIG.
When the radius of curvature of the work surface of the work W ₀ is small, the pressing force T _{1 of the} kansashi pressed in the Z-axis direction increases from the state perpendicular to the work surface of the work W _{0 at} the peripheral edge thereof. I will tilt. Therefore polishing load T ₂ acting in the normal direction of the surface to be processed of the workpiece W ₀ to (T ₁ cos [theta]) is significantly reduced compared to the central portion of the workpiece W _0, the polishing amount becomes uneven.

[0007] Once the amount of polishing in this manner nonuniform central portion and peripheral portion of the workpiece W _0, it is impossible to finish the curvature of the surface to be processed of the workpiece W ₀ after polishing the same as before polishing.

[0008] This tendency is a serious disadvantage particularly in a situation where the width of the polishing tool in the X-axis direction must be reduced to perform polishing. For example, when polishing a work surface having an aspherical shape in the generatrix direction or the sagittal direction, it is necessary to use a polishing tool having a small contact area with the work surface, so that uniform polishing is extremely difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art. Even when the radius of curvature of a work surface of a workpiece is small, troubles such as a reduction in the amount of polishing at the peripheral edge thereof are caused. It is an object of the present invention to provide a high-performance polishing apparatus and a high-performance polishing method capable of extremely uniformly polishing the entire surface to be processed while avoiding the problem.

[0010]

In order to achieve the above object, a polishing apparatus according to the present invention comprises a work holder for holding a work, and a work holder for pivoting the work holder about a first axis. A first drive unit, a second drive unit for pivoting the work holding table around a second axis, a polishing tool for polishing a work surface of the work, and a third And a rotating means for rotating the polishing tool.

Also, a first swing stage pivotally supported on a base plate around a first axis, first driving means for pivoting the first swing stage, and the first swing stage. A second swing stage pivotally supported on a second stage about a second axis, and a second swing stage for pivoting the second swing stage;
Driving means, a work holding table supported by the second swing stage, a polishing tool for polishing a work surface of the work held by the work holding table, and the polishing tool being mounted on a third shaft. A third driving means for reciprocating the polishing tool along with a rotating means for rotating the polishing tool may be provided.

It is preferable that an inclination angle adjusting means for changing the inclination angle of the polishing tool is provided.

It is preferable that a separation distance adjusting means for adjusting a separation distance of the work holding table with respect to the first axis is provided.

It is preferable that a second separation distance adjusting means for adjusting a separation distance of the work holding table with respect to the second axis is provided.

The rotating means may include a revolving mechanism for revolving the polishing tool around a third axis and a rotating mechanism for revolving the polishing tool.

[0016]

The polishing tool is pressed against a work having a curved work surface such as a toric shape, and the work holding table for holding the work is swung about the first and second axes, thereby generating a bus of the work. The feed is performed in the machine direction and the sagittal direction, and the entire surface to be processed is polished. The pressing force of the polishing tool on the work surface is
It is controlled by the third driving means. If the first and second axes are located at the center of curvature or approximate curvature in the generatrix direction and the sagittal direction of the work, when polishing the peripheral portion of the work,
There is no possibility that the pressing force of the polishing tool is inclined with respect to the work surface of the work.

Even if the radius of curvature of the work surface of the work is small, the polishing load on the entire work surface can be made extremely uniform without reducing the polishing load at the peripheral edge of the work.

It is possible to prevent the amount of polishing from becoming uneven between the central portion and the peripheral portion of the work, and to polish and finish the mirror surface portion and the like of the toric mold with high accuracy.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

[0020] Figure 1 is a perspective view showing a polishing apparatus according to an embodiment, which is to be processed surface of the workpiece W ₁ is a toric mold after diamond precision cutting, polishing tool 10 of hemispherical while rotating against a workpiece and generating line direction (Y-axis direction) the radius of curvature of the surface to be processed of the workpiece W ₁ is the maximum, in the sagittal direction the radius of curvature of the surface to be processed is the minimum (X axis direction) By sending W ₁ , the work W ₁ and the polishing tool 10 are rubbed.

Work holding table 20 on which work W ₁ is placed
Is supported by a free end of an arm 31 which is a second swing stage projecting from the X swing mechanism 30,
Is supported by a free end of an arm 41 which is a first swing stage protruding from the Y swing mechanism 40.

The Y swing mechanism 40 has a substantially U-shape suspended on the upper ends of a pair of supports 51 erected on a base 50 so as to be pivotable.
It has a character-shaped frame, and an arm 41 protrudes from one side edge of the frame in the Y-axis direction. A linear slide 42, which is a separation distance adjusting means disposed at a free end of the arm 41, supports the support 43 of the X swing mechanism 30, and adjusts the position of the X swing mechanism 30 in the vertical direction (Z axis direction). It is adjustable. Support 4
An X swinging mechanism 30 is suspended at the upper end of 3 so as to be pivotable.

The generatrix direction of feed of the workpiece W ₁ is pivotally the Y swing mechanism 40 with X swinging mechanism 30, about an axis 40a which is a first shaft by a pulse motor M ₁ is a first driving means It is performed by moving (swinging).

[0024] In addition, the sagittal direction of the feed of the workpiece W ₁ is, Y
Is performed by pivoting (swinging) the X swing mechanism 30 on the swing mechanism 40 about the second by a pulse motor M ₂ is a driving means which is a second shaft axis 30a.

[0025] The swing radius of the generatrix direction of the work W ₁ configuration, the linear slide 42 to the position of the support 43 of the X rocking mechanism 30 as described above is performed by adjusting the Z-axis direction.

The swing radius of the work W ₁ in the sagittal direction is the second swing distance between the work holding table 20 and the work W ₁ .
Is adjusted by changing the thickness (height) of the jig 21 which is the separation distance adjusting means. Thus, by matching the center of rocking motion of the center and the sagittal direction of the workpiece W ₁ of the curvature or approximate the curvature of the sagittal direction of the processed surface of the workpiece W _1, the work W ₁ in the sagittal direction swing Even polishing tools 10
Can pressurization direction is adjusted to always coincide with the normal direction of the surface to be processed of the workpiece W _1. If the aspherical amount of the work W ₁ is large, the aspherical surface displacement from spherical to set the swing radius so that the most decreases. The adjustment in the generatrix direction is similarly performed using the linear slide 42.

When the thickness of the jig 21 is changed, the swing radius in the generatrix direction also changes.
To finely adjust the swing radius in the generatrix direction is required.

The polishing tool 10 includes a motor M as a rotating means.
_The polishing head 11 is held by a polishing head 11 which is rotated by an air cylinder 1.
2 pressurizes in the Z-axis direction. Air cylinder 12
Moves the slide 13a supported on the side surface of the column 13 erected on the base 50 in the Z-axis direction. Slide one
Reference numeral 3a supports a support 14 which is a tilt angle adjusting means for supporting the polishing head 11 in a cantilever manner so as to be rotatable around an axis 11a. By rotating the support 14 about the axis 11a, the inclination angle of the polishing head 11 can be changed.

[0029] When the workpiece W ₁ is a toric mold, since the polishing load required by the small, used friction-less air cylinders so that there is no influence of the friction by the air cylinder 12. If the weight of the polishing head 11 is too large, a reverse pressure is applied to the air cylinder 12 to adjust the pressure to an appropriate value.

[0030] Figure 2 shows a polishing tool 10, which has a shaft 10a which is rotated by a motor M _3, the hemispherical abrasive pad 10b held in the tip. As the polishing pad 10b, a material in which a material having a polishing ability such as a thin-walled pitch or urethane is adhered to a hemispherical elastic body is used. As described above, the polishing head 11 is
When rotated about the polishing tool 10 is inclined, the contact portion is the motor M of the polishing pad 10b for the workpiece W _{1
Since the} center of rotation of the polishing tool 10 by ₃ is deviated, the rotational peripheral speed at the contact portion changes continuously without an inflection point. Therefore, it is possible to perform smooth polishing while avoiding a sharp change in the polishing amount.

The contact area between the polishing tool 10 and the work W ₁ is:
Since it changes depending on the curvature and the pressing force of the polishing pad 10b, a desired contact area can be obtained by changing either one.

The polishing operation is pressing the polishing tool 10 to the work surface of the workpiece W ₁ on the workpiece holding table 20, while the polishing tool 10 is rotated, and sends the work holding base 20 in the X-axis direction and the Y-axis direction It is done by doing. As a pattern for controlling the feeding, three types of feeding patterns are generally used as described later (see FIG. 5).

[0033] X-axis direction of the feeding is performed by swinging about the Y-axis direction of the shaft 30a in the X rocking mechanism 30 in the sagittal direction of the radius of curvature of the center of the workpiece W _1.
Feeding in the Y-axis direction is also performed by swinging the Y swing mechanism 40 around an axis 40a in the X-axis direction. Thus, even at the end portion of the X-axis direction of the work W _1,
Even at the end portion of the Y-axis direction, pressure of the polishing tool 10 acts perpendicularly to the work surface of the workpiece W _1. As a result, the polishing load is always constant, and the amount of polishing on the entire surface to be processed can be made uniform.

Furthermore, and with the polishing surface of the small spherical with the contact area on the polishing tool 10, which, because it is held inclined with respect to the processed surface of the workpiece W _1, the workpiece W ₁ treated surface of the Even if the radius of curvature is small, extremely uniform polishing can be performed at a high speed.

[0035] Figure 3, the outer shape is circular or rectangular shape, showing a polishing tool 60 used when the processed surface of the workpiece W ₂ is relatively large. This is the tip of the shaft 61a, an elastic body 60a of the inner rubber, in which the surface layer 60b having a polishing pad 61b of double structure having the polishing ability, the curvature of the contact portion between the workpiece W _2, a polishing tool of toric shape that the respective average curvature sagittal direction and the generatrix direction of the work surface of the work W ₂ is a toric mold.

In this case, an orbital rotation mechanism 62 as shown in FIG. 4 is used, and only the revolving motion is given without substantially rotating the polishing tool 60 so that the direction of the polishing tool 60 does not change. . That is, the elastic deformation of the contact surface of the polishing tool 60 is minimized, and the polishing removal efficiency is increased by the orbital motion. The rotating circle mechanism 62 rotates the rotating shaft 62a by a motor which is a revolution mechanism, and rotates the pin joint 62b.
The revolving motion is transmitted to the polishing tool 60 via the. Tool axis 61
The gear 62c, which is a rotation mechanism integrated with the gear a, meshes with the internal gear 62d on the fixed side, and the polishing tool 60 makes one rotation while the gear 62c makes one revolution.
It is configured so that the direction of 0 does not change.

When the external shape of the workpiece is rectangular, the external shape of the polishing tool is also rectangular, and a linear reciprocating motion is added instead of the motion of the rotating circle, so that the polishing amount is uniform at the corner of the surface to be processed. To be able to

In some cases, the tool shaft is rotated at the center of the polishing tool to increase the removal efficiency and scan the surface to be machined without adding a rotating circle or a linear reciprocating motion to the tool shaft.
The shape of the spherical body having the entire mean curvature of the sagittal wire or the elasticity of the tool material is further reduced and softened, so that the polishing tool can easily follow the shape of the work even if the direction changes due to the rotation of the polishing tool.

An embodiment in which polishing is performed using the polishing apparatus shown in FIG. 1 will be described below.

(Example 1) The outer shape is 8 x 16 mm, the radius of curvature in the generatrix direction is concave 30 mm, and the radius of curvature in the sagittal direction is concave 2
0mm KN plated toric mold surface, 6mm outer shape
Oscillating polishing was performed in the generatrix direction and the sagittal direction using a rectangular plate-like polishing tool having a convexity of 20 mm with a corner and a contact surface with a radius of curvature of 0.5 mm with a period of 0.5 sec.

The construction of the polishing tool is a urethane foam sheet having a surface of 0.5 mm and neoprene rubber having a thickness of 3 mm inside.

Example 2 The outer shape is 6 × 12 mm, the radius of curvature in the generatrix direction is 25 mm, and the radius of curvature in the sagittal direction is 1 concave.
The radius of curvature is 1 on the 8 mm KN plated toric mold surface.
An 8 mm urethane resin hemispherical polishing tool was inclined by 30 degrees, and polished while applying a load of 200 g and rotating at a rotation speed of 60 rpm with a contact width of 3 mm.

Example 3 The outer shape is 8 × 16 mm, the radius of curvature in the generatrix direction is 30 mm, and the radius of curvature in the sagittal direction is 2 concaves.
5m diameter on 0mm KN plated toric mold surface
m, a disk-shaped polishing tool with a contact surface radius of curvature of 20 mm for 30 r
While rotating at pm and pressing at 100 g, the entire surface of the mold was scanned and polished. The swing cycle for scanning is 1 in the sagittal direction.
The entire surface was scanned twice in 10 seconds in the generatrix direction.

Next, the above-described workpiece feed pattern will be described. As shown in FIG. 5A, the process of repeating the zigzag movement of the work in the generatrix direction is repeated, and as shown in FIG. 5B, the work is scanned in the generatrix direction and then slightly moved in the sagittal direction. In general, there are three types: a process of moving the workpiece in the generatrix direction and a process of scanning the workpiece in the generatrix direction, as shown in FIG.

FIG. 6 is a flowchart showing a control program based on the feed pattern shown in FIG. In step S1, the rotation of the polishing tool is started. In step S2, the air cylinder is driven to lower the polishing tool. In step S3, swinging in the sagittal direction is started. In step S4, the polishing tool is advanced in the generatrix direction. To stop the feed in the generatrix direction, and in step S6, to feed a fixed amount in the sagittal direction.
7, the position in the sagittal direction is confirmed. In step S8, the vehicle is moved backward in the bus direction. In step S9, the feed in the bus direction is stopped.
In step S10, the sheet is sent in the sagittal direction. In step S11, the position in the sagittal direction is confirmed. If the position is not the end point in the sagittal direction, the process returns to step S4. When the end point in the sagittal direction is reached, the feed in the sagittal direction is stopped in step S12, the rotation of the polishing tool is stopped in step S13, and the polishing tool is raised in step S14, and the process is terminated.

FIG. 7 is a flowchart showing a control program based on the feed pattern shown in FIG. 5B. In step S21, rotation of the polishing tool is started, and in step S2
In step S2, the air cylinder is driven to lower the polishing tool. In step S23, the feed in the generatrix direction is started.
In step 4, advance in the generatrix direction is stopped, and in step S25, feed is performed in the sagittal direction by a fixed amount. In step S26, feed is stopped.
In step S27, the position in the sagittal direction is confirmed.
At 28, the vehicle is moved backward in the bus direction, and the process returns to step S23.
If the end point in the sagittal direction has been reached in step S27, the rotation of the polishing tool is stopped in step S29, and step S3
At 0, the polishing tool is raised and the process is terminated.

FIG. 8 is a flowchart showing a control program based on the feed pattern shown in FIG. In step S41, the rotation of the polishing tool is started, and in step S4
In step 2, the air cylinder is driven to lower the polishing tool, and in step S43, the polishing tool is advanced in the generatrix direction. In step S44, the polishing tool is sent in the sagittal direction. In step S45, the position in the sagittal direction is confirmed. If not, the flow goes back in the bus direction in step S46 and returns to step S44. Step S
If the end point in the sagittal direction has been reached at 45, step S4
7, the feed in the sagittal direction is stopped, the rotation of the polishing tool is stopped in step S48, and the polishing tool is raised in step S49, and the process ends.

[0048]

Since the present invention is configured as described above, it has the following effects.

Even if the radius of curvature of the work surface of the work is small, the amount of polishing at the peripheral portion can be prevented from being significantly reduced, and the entire work surface can be uniformly polished. In particular, it is most suitable for polishing the mirror surface of the toric mold after the diamond precision cutting, and can greatly contribute to high performance of a lens having a toric shape or the like.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a polishing apparatus according to an embodiment.

FIG. 2 is an elevational view showing only the polishing tool of the apparatus of FIG. 1;

FIG. 3 is a cross-sectional view illustrating a polishing tool according to a first modification.

FIG. 4 is a sectional view showing the polishing tool of FIG. 3 and a drive unit thereof.

FIG. 5 is a diagram showing three feed patterns.

FIG. 6 is a flowchart illustrating a feed pattern of FIG.

FIG. 7 is a flowchart illustrating a feed pattern of FIG. 5 (b).

FIG. 8 is a flowchart illustrating a feed pattern of (c) of FIG. 5;

FIG. 9 is a diagram illustrating a polishing apparatus according to a conventional example.

FIG. 10 is a diagram illustrating a polishing load in the apparatus of FIG. 9;

[Explanation of symbols]

 10, 60 Polishing Tool 11 Polishing Head 12 Air Cylinder 20 Work Holder 30 X Swing Mechanism 40 Y Swing Mechanism 50 Baseboard 62 Circulation Circular Mechanism

Claims (7)

[Claims] A work holding table for holding a work, and a first table for pivoting the work table about a first axis.
Driving means, a second driving means for pivoting the work holding table around a second axis, a polishing tool for polishing a work surface of the work, and a third axis for the polishing tool. A polishing apparatus comprising: third driving means for reciprocating along the axis; and rotating means for rotating the polishing tool. 2. A first oscillating stage pivotally supported on a base plate around a first axis, first driving means for pivoting the first oscillating stage, and the first oscillating stage. A second swing stage pivotally supported on a second stage around a second axis, second driving means for pivoting the second swing stage, and a second swing stage supported by the second swing stage; A work holding table, a polishing tool for polishing a work surface of a work held by the work holding table, third driving means for reciprocating the polishing tool along a third axis, A polishing apparatus having a rotating means for rotating a polishing tool. 3. The apparatus according to claim 1, further comprising an inclination angle adjusting means for changing an inclination angle of the polishing tool.
Or the polishing apparatus according to 2 above. 4. The polishing apparatus according to claim 1, further comprising a separation distance adjusting means for adjusting a separation distance of the work holding table with respect to the first shaft. 5. The polishing device according to claim 1, further comprising a second separation distance adjusting means for adjusting a separation distance of the work holding table with respect to the second shaft. apparatus. 6. The apparatus according to claim 1, wherein said rotating means includes a revolving mechanism for revolving the polishing tool about a third axis, and a rotating mechanism for revolving the polishing tool. The polishing apparatus according to the above item. 7. A step of feeding the work in two orthogonal directions while bringing a polishing tool into contact with the work surface of the work, wherein the work is formed around an axis located at the center of curvature of the work surface. A polishing method characterized in that feed is performed in each axial direction by pivoting a shaft.