JP2003039294A - Curved surface processing device and curved surface processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process a workpiece such as an optical element having a non-axisymmetric surface having a large or complex shape with a large asymmetric component with a good surface roughness. In a processing apparatus, a processing tool 27 is set to P
It is installed on the TZ stage 26a so that the processing tool can control the volume change of the PTZ during the processing and make a small displacement. The PTZ stage 26a is driven and controlled in synchronization with the rotation of the main spindle on which the non-workpiece is mounted, and the processing tool 27 is displaced in parallel with the main spindle by a displacement amount corresponding to the rotation position of the rotating workpiece. Perform processing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved surface processing apparatus and method for processing a non-processed object having a curved surface, for example, an asymmetrical processed surface such as an optical element.

[0002]

2. Description of the Related Art For example, in a recording / reproducing apparatus for a CD, a DVD, etc., a non-axial symmetry (analog) is used for high efficiency use of a recording system laser in an optical pickup and correction of a reproducing system laser AS (astigmatism). Morphic, toroidal, etc.)
Many optical elements are used. Further, even in an imaging optical system such as a camcorder, a non-axisymmetric optical element is required in order to cope with a high angle of view, so that the demand for a non-axisymmetric optical element has been particularly increased in recent years. By the way, in order to obtain a non-axisymmetric optical element, currently, for example, (1) a direct cutting method for directly processing a material to obtain a predetermined shape,
(2) There is a method of molding using a mold (plastic injection molding, glass reheat press molding, etc.).

FIG. 5 is a perspective view schematically showing a conventional processing apparatus. The processing apparatus 10 is roughly a first base 1
4, a Z-direction stage 13 slidably provided on the spindle 4, a spindle 11 on the Z-direction stage 13, a second base 22 of the processing tool side portion 20, an X-direction stage 21 on the base 22,
The processing tool 27 is mounted on the X-direction stage 21. A ridge 15 for guiding the Z-direction stage 13 is provided on the upper surface of the base 14, while a groove 16 corresponding to the ridge 15 is formed on the lower surface of the Z-direction stage 13. The Z-direction stage 13 is reciprocally displaced by being guided by the protrusion 15 on the base 14 by the rotation of the rotary shaft 19b which is rotationally driven by the motor 19 via the transmission mechanism 19a, and at the same time, the main shaft 11 and the workpiece. The mounting spindle plate 17 is similarly displaced. A main shaft 11 and a motor 18 for rotating the main shaft 11 are arranged on the Z-direction stage 13, and an angle sensor (C axis) 12 for detecting a rotation angle of the main shaft 11 is provided at a rear portion of the main shaft 11. It is built in.

Base 2 of the processing tool side portion 20 of the processing apparatus
2 A ridge 2 for guiding the X-direction stage 21 on the upper surface
3 is provided, while a groove 24 corresponding to the protrusion 23 is provided on the lower surface of the X-direction stage 21. The X-direction stage 21 can be reciprocally displaced by being guided by the protrusion 23 on the second base 22 by the rotation of the rotating shaft 28b that is rotationally driven by the motor 28 via the transmission mechanism 28a. On the upper surface of the base 22, there is a B axis 25 for constantly controlling the attitude of the processing tool 27 in the normal direction to the processing surface, and a tool stage 26 is installed on the upper surface thereof.

The processing tool 27 is the tool stage 2 described above.
6 and 6 on the X-direction stage 21. Here, the X-direction stage 21 is arranged orthogonally to the Z-direction stage 13 and performs radial positioning of the position of the processing tool 27 with respect to the workpiece to be processed.

When performing non-axisymmetric processing using the processing apparatus 10 described above, the object to be processed is mounted on the spindle face plate 17 of the spindle 11 and rotated by the motor 18,
The Z-direction stage 13 is slightly displaced by driving a motor 19 in synchronization with the rotation of the main shaft 11 in accordance with a non-axisymmetric machining surface shape, and the tool 2 positioned in the radial direction of the non-machining object.
The object to be processed is cut (cut) with respect to 7. Figure 6
Shows the relationship between the rotation angle of the spindle 11 during processing and the displacement (sag deviation) of the Z-direction stage 13 in the Z direction (sag referred to as the processing target). When machining a non-axisymmetric surface such as an anamorphic or toroidal surface, the Z-direction stage 13 rotates the main shaft 11 one revolution (360
It moves in the Z direction during the rotation. Considering a certain diameter of the workpiece around the spindle 11, the Z-direction displacement is sin wave-like with respect to the rotation angle, and the displacement of the Z-direction stage during one rotation is large toward the outer periphery, and near the center. Conversely, it becomes smaller and the center becomes 0. In the figure, for example, φ = 4.
As is clear from the relationship between the rotation angle and the sag deviation at 0, φ = 2.0, and φ = 1.0, it can be seen that the sag deviation decreases as φ decreases.

As described above, in the conventional processing apparatus, in order to process an axisymmetric optical element, the Z-direction stage 13 is reciprocally displaced in the Z direction in a sin wave shape while the main shaft 11 is rotated once. However, since the spindle 11 including the motor 18 and the like and the weight of the object to be machined are added on the Z-direction stage 13, the weight becomes large, and the deterioration of the responsiveness due to the inertia is unavoidable, and as the rotation speed of the spindle 11 is increased. The problem of displacement delay is exacerbated. In other words, it becomes difficult to follow the Z-direction stage 13 while the main shaft 11 is rotating at a high speed, and the surface roughness is disadvantageous particularly in the cutting process.

Next, description will be made on a case where grinding is performed by using the conventional processing apparatus. Since the grindstone, which is a processing tool, can be rotated in the grinding process, there is an advantage that the relative rotation speed is increased and the spindle 11 does not have to be rotated at a high speed in terms of surface roughness. However, even if it is a non-axisymmetric surface that takes a large amount of displacement, the Z-direction stage has a problem of responsiveness as in the case of cutting, and the same problem still occurs. In the optical element, since the final surface roughness of the element is increased to the optical mirror surface, it is particularly necessary to increase the relative speed between the object to be processed and the processing tool, although it depends on the material to be processed and the material of the processing tool. However, from the problem of displacement response of the Z stage described above,
In reality, the spindle rotation speed cannot be increased even in the non-axisymmetric grinding process.

The problems in the conventional processing apparatus are summarized as follows. Since the optical surface of the processing object needs to have a mirror surface, it is necessary to increase the relative speed between the processing object and the processing tool. However, in non-axisymmetric processing, displacement occurs because the Z direction displacement occurs for each rotation of the spindle. The weight of the object affects the displacement response. Even in the grinding process in which the relative speed of the Z stage can be changed, if the displacement stroke of the Z-direction stage becomes large, it becomes disadvantageous if the weight is large.

[0010]

Therefore, an object of the present invention is to eliminate the drawbacks of the conventional machining apparatus. Conventionally, the main spindle and the non-machined object are mounted during machining. In view of the fact that the responsiveness of the Z-stage has been affected by the rotational speed of the spindle due to the slight displacement, the structure of slightly displacing the lightweight machining tool instead of the spindle allows the Z-stage to respond. By solving the problem of reliability and increasing the rotation speed of the spindle 11, the machining efficiency and the surface roughness of the machined surface are improved, and at the same time, it is possible to sufficiently cope with the processing of a large non-axisymmetric component surface or a complicated surface. The purpose is to

[0011]

According to a first aspect of the present invention, a rotating means for rotating a workpiece, a machining tool driving means for displacing a machining tool of the workpiece, and a rotation of the rotating means are synchronized. And a means for driving and controlling the processing tool driving means, and the displacement tool drives the processing tool by a displacement amount according to the rotational position of the rotating workpiece.

A second aspect of the present invention is the curved surface machining apparatus according to the first aspect, wherein the machining tool is driven to be displaced in the direction of the rotation axis of the workpiece.

A third aspect of the present invention is the curved surface machining apparatus according to the first or second aspect, wherein the machining tool driving means includes a piezoelectric body.

According to a fourth aspect of the present invention, there are provided a step of rotating the work piece, and a step of displacing and driving the working tool in synchronization with the rotation of the work piece by a displacement amount corresponding to the rotational position of the non-work piece. It is a curved surface processing method characterized by having.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view schematically showing a processing tool side portion 20 of a processing apparatus 10 of the present invention.
Other configurations of 0 are the same as the conventional one. In the configuration shown in the figure, the same parts as the conventional ones are given the same numbers.
That is, the B axis 25 is installed on the X-direction stage 22, and the tool stage 26 and the processing tool 27 are placed on the B axis 25. Although this configuration is similar to that of the conventional processing apparatus described above, in the present embodiment, a piezoelectric material such as PZ is provided between the B axis 25 and the tool stage 26.
Stage made of T (lead zirconate titanate) (PTZ
Stage 26a is arranged.
The PZT stage 26a utilizes the fact that the PZT is distorted in accordance with the potential difference, and controls the PZT by the applied voltage so that the tool stage 26, and hence the machining tool 27, is slightly displaced in the Z direction by a desired amount. That is, during processing, the Z-direction stage 13 is used in the conventional processing apparatus.
Instead of performing the small displacement in the Z direction, in the present embodiment, the processing tool is slightly displaced in the Z method to perform cutting or grinding.

In the present embodiment, the PZT stage 26a is adopted to displace the machining tool side to enhance the displacement response, and the machining tool can be displaced in the same direction as the workpiece cutting direction with good responsiveness. With the improvement of the degree, it is possible to machine a surface with a large amount of non-axisymmetric displacement or a complicated surface.

FIG. 2 is a diagram (graph) showing the relationship between the rotational speed of the spindle 11 and the surface roughness in this embodiment. Here, FIG. 2A shows the relationship between the surface roughness Ra and the spindle rotation speed in the cutting process, and FIG. 2B shows the surface roughness Ra and the grindstone shaft rotation when the spindle speed is constant at 100 rpm in the grinding process. It shows the relationship with the number. The surface roughness Ra can be set to about 0.01 μm when the spindle speed is set to about 500 rpm during cutting, and the grinding wheel spindle speed reaches 4000 rpm when the spindle rotation is set to 100 rpm during grinding. Surface roughness Ra at the stage
It can be seen that can be made in a good state of about 0.01 μm. The machining control is based on the rotation of the spindle 11 by the spindle angle sensor (C
(Axis) 12 and the PZT stage 26a is displaced in synchronism with the rotation so that the desired non-axisymmetric optical element can be ground or cut. This displacement control is X,
The NC unit controls the Z and C axes in total, and the control itself is well known in the art.

Next, examples of the present invention will be described. A case will be described in which the optical surface (S2) on the disk side for correcting the astigmatic difference of the LD, which is the light source, in the finite CD objective lens is axisymmetric. Each coefficient of the aspherical expression of the non-axisymmetric S2 is, for example, R = −4.202019 K = −6.97 A4 = 0.00070 A6 = −0.0002 A8 = 2.15E-5 A10 = −1 in the X direction. .2E-6 Y direction R = -4.19595 K = -6.97 A4 = 0.00070 A6 = -0.0002 A8 = 2.15E-5 A10 = -1.2E-6

FIG. 3 is a diagram showing the relationship between the rotation angle of the spindle and the sag deviation during machining in this embodiment. As shown in the drawing, also in this embodiment, it can be confirmed that the sag deviation fluctuates like a sin wave during one rotation of the main shaft, and that the deviation fluctuates from the center toward the outer circumference. Further, R = 2.57 for the LD side optical surface S1.
It is an axisymmetric aspherical surface having 6. The symmetrical product is a SUS material plated with electroless nickel, and the plating layer was cut. As the processing conditions, processing was performed at a spindle speed of 500 rpm. Also, the PZT used was a flexure type from German PI, and the processing equipment was ULG-100C manufactured by Toshiba Machine.
P using the FANUC NC device using H3 (trade name)
The ZT was controlled.

4A and 4B are views showing the measurement results of the axisymmetric surface obtained as a result. X, Y as shown
It can be seen that the shape can be processed to be non-axisymmetric when the fitting is performed at the middle R of the direction. The surface accuracy when fitting in each direction is about 0.1 μm, which is good.
The surface roughness was Ra = 0.01 μm, which was good. In addition,
The case of processing a non-axisymmetric optical element has been described above, but the present invention is not limited to this, and for example, processing of a mold for molding the optical element, such as processing of a non-axisymmetric processing surface, is performed. It can be widely applied to objects.

[0021]

As described above, according to the present invention, a lightweight tool is displaced for machining. Therefore, even if the spindle is rotated at a high speed, the delay in response as in the case of displacing the conventional Z-direction stage does not occur, and the cutting is performed. In any of the grinding and grinding processes, it is possible to obtain a non-processed product having a good surface roughness. Also,
It is possible to easily form a surface having a large non-axisymmetric component, and it is possible to sufficiently process a complicated surface such as 4-rotation symmetry and 6-rotation symmetry.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing a processing tool side portion of a processing apparatus of the present invention.

FIG. 2 is a diagram for explaining the relationship between the rotational speed of the spindle and the surface roughness by the processing device.

FIG. 3 is a diagram showing a relationship between a rotation angle of a main shaft and a sag deviation in the embodiment of the present invention.

FIG. 4 is a diagram showing measurement results of an axisymmetric surface obtained by carrying out the present invention.

FIG. 5 is a perspective view schematically showing a conventional processing apparatus.

FIG. 6 is a diagram showing a relationship between a rotation angle of a spindle and a sag deviation in a conventional processing device.

[Explanation of symbols]

10 ... Processing device, 11 ... Spindle, 12 ... Angle sensor (C
Axis), 13 ... Z-direction stage, 14 ... base, 15 ... ridge, 16 ... groove, 17 ... spindle face plate, 19 ... motor, 19a
... Reduction mechanism, 22 ... Base, 23 ... Projection, 24 ... Groove, 25
... B axis, 26 ... Tool stage, 26a ... PTZ stage, 27 ... Machining tool, motor 28, reduction mechanism 28a, rotary shaft 28b,

Claims (4)

[Claims] 1. Rotating means for rotating a workpiece, machining tool driving means for displacing and driving a machining tool for the workpiece, and driving control of the machining tool driving means in synchronization with rotation of the rotating means. And a means for displacing and driving the machining tool by a displacement amount according to a rotational position of a rotating workpiece. 2. The curved surface processing apparatus according to claim 1, wherein the processing tool is displaced and driven in a direction of a normal to a processing surface of a workpiece. 3. The curved surface processing apparatus according to claim 1, wherein the processing tool driving means includes a piezoelectric body. 4. A step of rotating a work piece, and a step of displacing and driving the working tool in synchronization with rotation of the work piece by a displacement amount according to a rotational position of the non-work piece. Curved surface processing method.