JPH10175150A - Curved surface polishing method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curved surface polishing method and device which improves the surface coarseness of a curved surface such as a nonspherical surface. SOLUTION: A polishing head 40 has a polishing tool 55 having a polisher function, and it moves freely in the Z-axis direction. A workpiece 100 is installed on a rotary table 80, and the rotary table 80 is installed on an inclined table 70. An X-axis table 20 and a Y-axis table 30 are loaded on a bed 10, and the inclined table 70 is installed on the Y-axis table 30. An (a) axis being the rotating center axis is provided parallel to the X-axis. By using this device, the coarsness of a curved surface such as a nonspherical surface which has been processed in a former process can be improved while maintaining the form accuracy of the curved surface.

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 rotating polyhedron, a lens, a mirror or the like having a curved surface, in particular, an aspherical surface having no axis of rotational symmetry (non-axisymmetrical aspherical surface), and a mold for molding the same. The present invention relates to a curved surface polishing method and apparatus for polishing a surface or the like with high accuracy.

[0002]

2. Description of the Related Art Conventionally, in the case of curved surface polishing, a method of applying a low-pressure load to a workpiece from a normal direction (a low-pressure load in the normal direction) has been used as a polishing method capable of keeping a processing amount constant in order to mirror finish without losing a shape. Polishing method) has been used. Especially,
For a workpiece with a non-axisymmetric aspherical shape without a rotational symmetry axis, the normal is controlled by synchronous control of a total of six axes, two axes for horizontal drive, two axes for tilt direction drive, tool rotation axis and tool vertical axis. Direction low pressure load polishing is performed. The following are the conventional techniques.

A table on which a workpiece is mounted is composed of two horizontal driving units (X and Y axes) and a three-axis driving unit of a c (θ) turning driving unit. The spherical polishing tool has a rotation axis and a tilt (tilt). Using a total 6-axis synchronous control polishing apparatus having three axes of an axis and a Z axis and a polishing apparatus having a shape measuring unit for measuring the surface shape data of the workpiece, and swinging the polishing head,
One that performs curved surface processing (Japanese Patent Application Laid-Open No. 5-57606). The table on which the workpiece is mounted is composed of two horizontal drive units (X and Y axes) and two tilt (tilt) drive units (a and b axes). Has two axes, a rotation axis and a Z axis.
Curved surface processing by an axis synchronous control device (Japanese Patent Laid-Open No. 8-19)
No. 2348). The table on which the workpiece is mounted is composed of two horizontal drive units (X and Y axes), a lateral rotation (θ) axis unit, and a tilt (tilt b axis) direction drive unit. A polishing tool that has two axes, a rotation axis and a Z axis, and performs curved surface processing by a total of six axes synchronous control device is also conceivable.

[0004]

However, the conventional polishing method and polishing apparatus have the following problems with respect to a workpiece having an aspherical shape (free-form surface shape) having no axis of rotational symmetry. there were. In any of the above-described techniques, only one non-axial aspherical surface can be polished, and a rotating polyhedron having a non-axially symmetric aspherical shape cannot be processed. In addition, although non-axial aspherical surfaces can be processed without losing the shape, there is a problem that the device becomes large and expensive, and the device is reduced in size. In this case, there is a problem that local deep digging occurs.
Accordingly, an object of the present invention is to provide a curved surface polishing method and a curved surface polishing apparatus capable of polishing a rotating polyhedron having an aspherical shape having no rotational symmetry axis (non-axisymmetric aspherical shape) with good shape accuracy. It is to be. Another object is to provide an inexpensive curved surface polishing apparatus.

[0005]

In order to solve the above-mentioned problems, the present invention provides a polishing head having a polishing tool having a substantially spherical shape and made of an elastic material, and a relative horizontal position of a processing surface with respect to the polishing head. A horizontal drive for moving, a turning drive for turning the workpiece around the center axis of the workpiece, a tilt drive for tilting the rotary drive, a synchronous control of the horizontal drive, the rotary drive, and the tilt drive. The present invention provides a curved surface polishing method and a curved surface polishing apparatus, comprising: a driving unit; and a processing surface that is always directed in a normal direction to a polishing head.

[0006] In addition to the above-mentioned configuration, the present invention also provides a method and an apparatus for polishing a curved surface, characterized in that a side surface of a processing surface is attached in parallel with a turning drive unit. By providing the above means, it is possible to keep the unit removal shape of a rotating polyhedron having an aspherical shape without a rotational symmetry axis, a constant,
Polishing can be performed with good shape accuracy. Further, an inexpensive curved surface polishing apparatus can be provided.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing the entire configuration of a curved surface polishing apparatus according to the present invention, FIG. 2 is a perspective view showing the configuration of a polishing head, and FIG. 3 is a cross-sectional view showing a main part of a polishing tool. . The curved surface polishing apparatus generally designated by reference numeral 1 has a first table 20 guided on a bed 10 along an X-axis along a guide (not shown), and the table 20 has an X-axis provided with a servomotor and a ball screw. Drive control is performed by the shaft drive device 22. On the first table 20, a second table 3 sliding on a Y axis orthogonal to the X axis along a guide (not shown)
The drive is controlled by a Y-axis drive device 32 equipped with a servo motor and a ball screw. Second table 3
The polishing head 40 is provided on the Z axis perpendicular to 0.

The polishing head 40 is disclosed in Japanese Patent Application Laid-Open No. 8-19234.
No. 8 has the same configuration as that disclosed in Japanese Patent Publication No. FIG.
As shown in FIG. 2, the polishing head 40 includes an air slide 41 that is swingable in the vertical direction, a spindle 42 fixed to the air slide 41, and a rotation shaft 43 of the spindle 42.
And a polishing tool 44 attached to the end of the polishing tool. The air slide 41 is connected to weights 47 via pulleys 45 a and 45 b and wires 46. The weight of the weight 47 is set so that the difference between the total weight of the air slide 41, the spindle 42, and the polishing tool 44 becomes a predetermined pressure. The polishing tool 44 is pressed against the processing surface of the workpiece by this pressing force.

FIG. 3 shows details of the polishing tool 44 and its spindle. The rotating shaft 43 of the spindle 42 has a bearing 49 fixed by housings 48a and 48b.
a, 49b rotatably held. One end of the rotating shaft 43 is connected to a servomotor 51 via a coupling 50, and the opposite end of the rotating shaft 43 is
4 is attached. The rotation speed of the servo motor 51 is controlled by a driver (not shown). Polishing tool 4
The mounting portion 4 has a rotation axis 43 and the same rotation center, and is removably mounted with a tool axis 53 that is made to rotate with the rotation shaft 43 by a fixing pin 52. Thus, the polishing tool can be changed according to the material and size of the workpiece. The tip 53a of the tool axis 53 has a spherical shape, and the periphery of the tip 53a has a hardness of 40.
The elastic body 54 is formed so as to be covered in a spherical shape by a soft elastic body 54 such as silicone rubber having a temperature equal to or less than 0 ° C. Further, a polisher for holding an abrasive and performing a polishing process is formed on the surface of the elastic body 54.

On the second table 30, which is a Y-axis table, a tilt table driving device 60 is provided. The third table 70 supported by the tilt table driving device 60 is tilt-driven around an a-axis parallel to the X-axis. The inclination angle is controlled by the driving device 60. On the third table 70, which is a tilt table, a fourth table 80, which is a rotary table, is provided. Rotary table 8
0 is driven to turn around the b-axis by a drive device provided in the tilt table 70, and the turning angle is controlled.

The rotary polyhedron 100 having a non-axial aspherical surface, which is a workpiece, is mounted on the rotary table 80 with its center of rotation C ₁ aligned with the rotary axis b of the rotary table 80. In this state, the polisher 55 as a polishing tool of the polishing head 40 is brought into contact with the processing surface 110 of the workpiece 100, and the processing surface 110 is polished using a polishing cloth and an abrasive. The polishing head 40 moves freely in the Z-axis direction. That is, the polisher 55 performs a polishing process for improving the surface roughness of the processed surface without changing the profile of the processed surface 110.

The NC data transferred from control software that can calculate the X coordinate, the Y coordinate, the tilt angle, and the vertical turning angle so that the processing surface always faces the normal direction with respect to the polishing head can be used as shown in FIG. The polishing apparatus 1 operates. This allows
Polishing can be performed efficiently with good shape accuracy and surface roughness. In addition, it is possible to polish a rotating polyhedron having an aspherical shape having no axis of rotational symmetry (non-axisymmetrical aspherical shape) with good shape accuracy.

[0013]

According to the present invention, when one surface having an aspherical shape having no rotational symmetry axis (non-axisymmetric aspherical shape) is machined, the shape accuracy is 0.8 μm and the surface roughness is 0 in the pre-machining. .
Do not break the shape created in 1 μmpv (shape accuracy of 0.
8 μm) and the surface roughness can be improved to 0.02 μm PV. In addition, an inexpensive curved surface polishing apparatus having a simple structure can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of a curved surface polishing apparatus according to the present invention.

FIG. 2 is a perspective view showing a configuration of a polishing head of the curved surface polishing apparatus of the present invention.

FIG. 3 is a sectional view showing a configuration of a polishing tool and a drive spindle.

[Explanation of symbols]

1 curved surface polishing apparatus, 10 heads, 20 X-axis table, 30 Y-axis table, 40 polishing head,
60 tilt drive, 70 tilt table, 80 turntable, 100 workpiece.

Claims (4)

[Claims] 1. A polishing head having a polishing tool having a substantially spherical shape and made of an elastic material, a horizontal drive section for moving a horizontal position of a workpiece, and a turning drive for rotating the workpiece about a central axis of the workpiece. A curved surface polishing method, characterized in that a processing surface is always directed in a normal direction with respect to a polishing head by synchronously controlling all of a driving unit and a tilt driving unit that tilts a turning driving unit. 2. The curved surface polishing method according to claim 1, wherein a side surface of the processing surface is attached in parallel to the turning drive unit. 3. A bed, a horizontal moving table driven and controlled along two axes orthogonal to each other on a bed, and a polishing head slidably disposed along an axis perpendicular to the horizontal moving table. A rotary polishing tool having a substantially spherical shape and made of an elastic material attached to a polishing head; a tilting table mounted on a horizontal moving table and moving around an axis parallel to one axis of the horizontal moving; It is equipped with a rotary table mounted on the table to support the work, and a control unit that controls each table synchronously, and controls the work surface of the work with respect to the polishing head so that it always faces in the normal direction. Curved surface polishing equipment. 4. The apparatus for polishing a curved surface according to claim 3, wherein said turntable includes means for supporting a workpiece on a side surface of a processing surface.