JPH10286771A - Grinding device and grinding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To grind an outer peripheral part of a surface to be worked similarly to an ordinary part, by changing the pressing force of a polisher corresponding to a position of the polisher. SOLUTION: When a polisher 30 reaches an outer edge of a face to be worked, and is extruded, the pressing force of the polisher 30 is reduced corresponding the extrusion amount. When the polisher is further moved, and a central axis of the rotation of a tool shaft is extruded, the angular moment acts on a grinding tool, which prevents the stable grinding, so that the upper limit value of the pressing force to stably perform the working even when the angular moment is generated, is determined in advance, and is built in a numerical arithmetic unit, and the grinding is executed by using this value. The shortage of the pressing force is compensated by increasing the number of revolution of the tool, shaft. When the polisher 30 is completely removed from the surface to be worked, and then is put to the surface to be worked again, the inverse working is executed. Whereby the grinding work of high accuracy can be easily performed.

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 suitable for mirror-finished curved surfaces of optical parts, semiconductor elements, ceramics, dies and the like.

[0002]

2. Description of the Related Art There has been known a polishing apparatus in which a polisher of a polishing tool is pressed against a surface to be processed and a relative motion is applied between the polisher and the surface to be processed to perform polishing.

For example, in the invention described in Japanese Patent Application Laid-Open No. 61-265257, polishing is performed while pressing a polisher at a constant pressure from the normal direction at each point on the surface to be processed.

In the invention disclosed in Japanese Patent Application Laid-Open No. 5-57606, the polishing tool is operated based on the error shape obtained from the shape measurement data of the surface to be processed so that the polishing removal shape becomes the same as the error shape. ing. At this time, the removal amount of polishing at each point on the surface to be processed is controlled by changing the time (residence time) for retaining the polishing tool at each point.

[0005]

[Problems to be solved by the invention]

<Problem 1> Generally, the removal amount of polishing is considered to be proportional to the relative speed V, pressure P, and processing time T of the polishing tool with respect to the surface to be processed. According to Preston's empirical formula, the polishing removal amount S is represented by (Formula 1).

[0006]

(Equation 1)

That is, in the above residence time control method,
By increasing the processing time T, the polishing removal amount S is increased,
An attempt is made to reduce the polishing removal amount S by shortening the processing time T.

However, as shown by the Preston's empirical formula, when the processing time T is increased, for example, to increase the amount of polishing removal, the relative speed of the polishing tool to the surface to be processed decreases by that much, and the polishing removal is rather performed. The amount may be reduced.

As described above, in the residence time control method, since it is necessary to operate two contradictory variables, it is very difficult to control the polishing removal amount.

<Problem 2> In the conventional polishing apparatus, since the polisher is moved only on the surface to be processed, as shown in FIG. 5, the traveling direction of the polisher is reversed at the outer peripheral portion of the surface to be processed. It is. On the other hand, in a normal portion of the work surface, the polisher is polished so as to pass over the normal portion. Accordingly, the outer peripheral portion of the processing surface cannot be polished in the same manner as the normal portion, and conventionally, the outer peripheral portion is a non-polished region.

In view of such a problem, an object of the present invention is to
An object of the present invention is to provide a polishing apparatus and a polishing method which are easy to control and can polish an outer peripheral portion of a processing surface in the same manner as a normal portion.

[0012]

According to a first aspect of the present invention for achieving the above object, a means for generating a pressing force for pressing a polisher against a surface to be processed, and the surface to be processed A polishing apparatus having means for moving the polisher pressed against the surface to be processed relative to the surface to be processed, comprising a control means for changing the pressing force according to the position of the polisher. An apparatus is provided.

In the first embodiment, the pressure (polishing pressure) applied to the surface to be processed by the polisher is used as a parameter for controlling the amount of polishing removed at each position of the surface to be processed.

The polishing pressure is different from the relative speed and the processing time, and changing the value has no effect on other parameters. Therefore, the control of the polishing removal amount is greatly simplified.

According to the first aspect, when the polisher protrudes from the surface to be processed, the pressing force is reduced according to the amount of protrusion, and when the polisher is completely detached from the surface to be processed. In the case where the pressing force is reduced to zero and the polisher re-enters the surface to be processed, the control may be such that the pressing force is gradually increased from the time when the polishing tool comes into contact with the surface to be processed, contrary to the above. It is possible. Thus, the outer peripheral portion of the processing surface can be polished in the same manner as the normal portion.

According to a second aspect of the present invention, there is provided a polishing apparatus, comprising: an expansion / contraction medium connected to a tool shaft of the polishing apparatus; And a driving means for changing the pressing force by changing the pressing force.

The second aspect is suitable for a hard polisher and controls the polishing pressure by the amount of expansion and contraction of an expansion and contraction medium (coil spring, air and oil filled in a cylinder).

According to a third aspect of the present invention for achieving the above object, the control means has a driving means for changing the pressing force by changing the amount of deformation of the polisher. A polishing apparatus is provided.

The third mode is suitable for a soft polisher. In this case, the crusher is controlled by a driving means by utilizing the elasticity of the polisher itself.

According to a fourth aspect of the present invention, there is provided a polishing method in which a polisher is pressed against a surface to be processed and the polishing is performed while the polisher is relatively moved with respect to the surface to be processed. In the method, there is provided a polishing method, wherein a pressing force of the polisher is changed according to a position of the polisher.

According to a fifth aspect of the present invention, there is provided a polishing method comprising reducing the pressing force when a part of a polisher protrudes from a surface to be processed. Provided.

According to a sixth aspect of the present invention, there is provided a polishing method comprising: when a part of a polisher protrudes from a surface to be processed, increasing the rotation speed of the polisher. Is provided.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a polishing apparatus 100 according to an embodiment of the present invention, a shape measuring apparatus 200 for measuring the shape of a workpiece 1, measured shape data, and a desired shape. And a numerical operation device 300 that calculates an error shape by calculating a difference between the two.

The polishing apparatus 100 is roughly divided into a mechanical section 2 for actually polishing the workpiece 1, and a control section 3 for controlling the mechanical section 2.

The workpiece 1 is fixed to a rotary table 10 which rotates around the W axis. The rotary table 10 is mounted on the X guide table 11, and linearly moves in the X direction along the X guide table 11 by driving of the motor 12. The X guide table 11 is mounted on a Y guide table 13, and is driven by a motor 14.
It moves directly in the Y direction along the guide table 13.

On the other hand, the Z slider 21 that moves linearly in the Z-axis direction
A rotating frame 23 that rotates around an axis is attached. The rotation frame 23 has A
A support 25 that rotates about an axis is attached. A rotation / linear movement mechanism 26 of a polishing tool is attached to the support 25.

When the shape of the workpiece 1 is non-rotationally symmetric, the rotary table 10 is stopped without rotating, and the polishing tool is pressed against the workpiece 1 by the rotation / linear motion mechanism 26. X-axis, Y-axis between workpiece 1 and polishing tool
The surface to be processed is polished by relatively giving a linear motion of each of the axes A and B and a rotational motion about each of the axes A, B and T. At this time, a polishing liquid is applied to the surface to be processed.

On the other hand, when the workpiece 1 is a rotationally symmetric object, the workpiece is rotated around the W axis by the rotary table 10, and the three axes of the X, Z, and A axes, or the Y, Z, axis,
Polishing is performed while sliding the polishing tool on one section on the surface to be processed by using one of the sets of the B axis.

Next, the rotation / linear motion mechanism 26 will be described.

The configuration of the rotation / linear motion mechanism 26 differs depending on the type of polisher used. When a hard polisher (for example, a resin represented by a urethane pad or a pitch) which is hardly elastically deformed is used, it is shown in FIG. With such a configuration,
When using a soft polisher that is easily elastically deformed,
The configuration is as shown in FIG.

In FIG. 2, a hard polisher 30 is fixed to a base plate 32 provided at a lower end of a tool shaft 31.
In the casing 33, the upper end of the tool shaft 31 is connected to the lower end of the coil spring 34 via a thrust bearing (not shown). A linear motion motor 35 is provided directly above the casing 33, and a push plate 38 attached to a tip of the linear motion shaft is connected to an upper end of the coil spring 34.

A rotating motor 36 is mounted on the side surface of the casing 33. The rotating shaft of the rotating motor 36 and the outer periphery of a ball spline (not shown) provided at the center of the tool shaft 31 , A belt 37. As described above, the tool shaft 31 is configured to be able to move up and down while rotating. In actual polishing, while rotating the tool shaft 31 around the T axis by the rotary motor 36, the linear motion motor 35 Changes the amount of expansion and contraction of the coil spring 34 to adjust the pressing force of the polisher. As the linear motor 35, for example, a voice coil motor is used.

On the other hand, in the case of a soft polisher, since the polisher itself has an elastic force, the pressing force of the polisher can be adjusted only by the amount of deformation of the polisher. In this case, as shown in FIG. 3, since the tool shaft 31 can be directly connected to the linear motion shaft of the linear motion motor 35 without using a coil spring, control accuracy of the pressing force is improved.

Next, a method of using the present processing system will be described.

First, the shape of the workpiece 1 is measured using the shape measuring device 200. FIG. 1 shows an optical interference measuring device as an example, but the present invention is not particularly limited as long as the measuring device can measure the shape of a workpiece. The shape measuring device can be roughly classified into a cross-sectional shape measuring type and a full-surface shape measuring type.In general, when the workpiece is a rotating object, the cross-sectional shape measuring type is used and the non-rotating object is used. In this case, use a full-surface shape measurement type.

When the measurement by the shape measuring device 200 is completed,
The shape data as the measurement result is transferred to the numerical calculation device 300 via the network.

The numerical operation device 300 calculates a difference between the transferred shape data and a desired target shape, and calculates an error shape. The calculation process of the error shape may be performed by the shape measuring device 200.

Further, the numerical operation device 300 determines a scanning method of the polishing tool for correcting the error shape based on processing conditions such as the shape and material of the workpiece, the shape and material of the polisher, and the material of the abrasive. Then, the file is transferred to the control unit 3 of the polishing apparatus 100 as a polishing tool control file.

The control unit 3 of the polishing apparatus 100 drives each motor in accordance with the transmitted polishing tool control file to cause the polisher 30 to slide on the surface to be processed and partially correct and polish the surface to be processed.

The specific operation of the polishing apparatus 100 is as follows.

In accordance with the contents of the transmitted polishing tool control file, the polishing apparatus 100 moves the three axes of the X axis, the Y axis and the Z axis and the A and B axes between the polishing tool and the workpiece 1. Polishing is performed by sliding the polisher 30 on the surface to be processed while giving a relative motion about two axes and keeping the tool shaft 31 in a posture coinciding with the normal direction of the surface to be processed. At this time, the linear pressure motor 35 adjusts the polishing pressure at each point to correct the error shape. That is, the moving speed of the polishing tool and the number of revolutions of the polishing tool are kept constant, and the increase and decrease of the polishing amount at each point on the surface to be processed are controlled only by the linear motion motor 35. Specifically, when a drive mechanism for a hard polisher as shown in FIG.
Adjust with the amount of expansion and contraction of 4. The relationship between the amount of expansion and contraction of the coil spring 34 and the pressing force for pressing the polisher 30 against the work surface is stored in the numerical calculation device 300 as a part of basic information for generating a polishing tool control file. I have. When a drive mechanism for a soft polisher as shown in FIG. 3 is mounted, the polishing pressure is adjusted by the amount of deformation of the soft polisher. These relationships are also stored in the numerical operation device 300.

When the polisher 30 reaches the outer edge of the work surface and the polisher 30 protrudes from the work surface, the pressing force for pressing the polisher 30 is reduced according to the amount of the protrusion. .

The relationship between the position of the polisher 30 and the pressing force is calculated by the numerical calculation device 300, and is, for example, as shown in FIG.

When the polisher 30 further moves and the rotation center axis of the tool axis protrudes (that is, when almost half of the polisher protrudes), in the state as it is,
A rotational moment acts on the polishing tool, and stable polishing cannot be performed. Therefore, the upper limit value of the pressing force that enables stable machining even when a rotational moment is generated is obtained in advance and incorporated in the numerical calculation device 300, and after the rotation center axis of the tool shaft protrudes, polishing is performed using this value. Is carried out. The insufficient pressing force is compensated for by increasing the number of rotations of the tool shaft. Since the number of rotations of the polishing tool is in a simple proportional relationship with the amount of polishing removal, the control is simple.

On the other hand, when the polisher 30 is completely separated from the surface to be processed and re-enters the surface to be processed, the reverse process is performed.

[0047]

According to the present invention, the increase or decrease of the polishing amount can be determined by using the polishing pressure that is independent of other control parameters, so that a highly accurate polishing operation can be performed more easily. Become.

Also, since the polishing pressure can be set arbitrarily at the outer peripheral portion of the workpiece, the outer peripheral portion can be polished in the same manner as the normal portion.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a processing system including an embodiment of a polishing apparatus according to the present invention.

FIG. 2 is a configuration diagram of a rotation / drive mechanism (No. 1) of one embodiment of the polishing apparatus according to the present invention.

FIG. 3 is a configuration diagram of a rotation / drive mechanism (part 2) of the polishing apparatus according to the embodiment of the present invention.

FIG. 4 is a graph showing a relationship between a pressing force and a polisher position used in one embodiment of the polishing apparatus according to the present invention.

FIG. 5 is an explanatory view showing the movement of a polisher of a conventional polishing apparatus.

[Explanation of symbols]

1: workpiece, 2: mechanical part of polishing apparatus, 3: control part of polishing apparatus, 10: rotary table, 11: X guide table, 12, 14, 20, 22, 24, 35, 36:
Motor, 13: Y guide table, 21: Z slider, 23: rotating frame, 25: support base, 26: rotation
Linear motion mechanism, 30: polisher, 31: tool shaft, 32: base plate, 33: casing, 34: coil spring, 37: belt, 38: push plate, 100: polishing device, 200: shape measuring device, 300: numerical value Arithmetic unit

Claims (6)

[Claims] 1. A polishing machine comprising: means for generating a pressing force for pressing a polisher against a surface to be processed; and means for moving the polisher pressed against the surface to be processed relative to the surface to be processed. The polishing apparatus according to claim 1, further comprising control means for changing the pressing force according to the position of the polisher. 2. The polishing apparatus according to claim 1, wherein said polishing apparatus includes means for generating said pressing force.
Polishing characterized by comprising an expansion / contraction medium connected to a tool shaft of the polishing apparatus, wherein the control means includes a driving means for changing the amount of expansion / contraction of the expansion / contraction medium in the tool axis direction to change the pressing force. apparatus. 3. The polishing apparatus according to claim 1, wherein said control means has a driving means for changing said pressing force by changing an amount of deformation of said polisher. 4. A state in which a polisher is pressed against a surface to be processed.
A polishing method for performing polishing while relatively moving the polisher with respect to a surface to be processed, wherein the pressing force of the polisher is changed according to the position of the polisher. 5. The polishing method according to claim 4, wherein the pressing force is reduced when a part of the polisher protrudes from the surface to be processed. 6. The polishing method according to claim 5, wherein when a part of the polisher protrudes from the surface to be processed, the rotation speed of the polisher is increased.