JP2007015199A - Method and apparatus for working optical element mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and apparatus for working an optical element mold which can form a recess in the shape of a lens with a small radius of curvature. <P>SOLUTION: In a working method for manufacturing a micro-lens mold 1 for molding the optical element having a plurality of independent optical function surfaces by working with the use of a diamond turning tool 3 for cutting a workpiece 1A, the diamond bit 3 is moved in the X-axis direction and simultaneously rotated around the Y-axis, and the workpiece 1A is moved in the Z-axis direction to cut the working surface 2 of the workpiece 1A. After that, the workpiece 1A is moved by a prescribed pitch in the Y-axis direction. The cutting and the movement are repeated to form the recess 2a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a processing method and a processing apparatus for an optical element mold.

  As a conventional processing method, a processing method using a fly-cut method described in JP-A-8-11223 is known.

  This processing method is as follows.

A diamond tool is attached to the main shaft and rotated using an ultra-precision processing machine with three or more axes simultaneously, while the work (workpiece) is fixed to a horizontal surface or a surface orthogonal to the shaft. While the diamond tool is scanned in the Z direction at a predetermined pitch, the workpiece is moved in the X and Y directions to remove a predetermined portion of the surface of the workpiece, thereby forming a recess corresponding to a desired lens shape.
JP-A-8-11223

  In order to form a concave portion having a small curvature radius, it is necessary to reduce the turning radius of the diamond tool.

  However, there is a limit in reducing the radius of curvature of the recess because the above-described processing method has problems such as interference between the main shaft to which the diamond tool is attached and the workpiece.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a processing method and a processing apparatus for an optical element mold capable of forming a recess having a small curvature radius.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a process for forming a mold for forming an optical element having a plurality of independent optical functional surfaces by processing using a tool for cutting a workpiece. In the method, movement of the workpiece in the direction of the Z axis perpendicular to the machining surface of the workpiece, movement of the tool in the direction of the X axis perpendicular to the Z axis on the horizontal plane, A machining step of machining the workpiece by simultaneously rotating the tool about a Y axis orthogonal to the Z axis and the X axis; and the workpiece in the direction of the Y axis with respect to the tool The moving step of relatively moving is repeatedly performed.

  The invention according to claim 2 is a processing method for forming a mold for forming an optical element having a plurality of independent optical functional surfaces by processing using a tool for cutting a workpiece. The workpiece is moved by simultaneously moving the workpiece in the direction of the Z axis perpendicular to the machining surface of the workpiece and moving the tool in the direction of the X axis perpendicular to the Z axis on the horizontal plane. It is characterized by repeatedly performing a machining step for machining a workpiece and a moving step for moving the workpiece relative to the tool in the direction of the Y axis perpendicular to the Z axis and the X axis. To do.

  According to a third aspect of the present invention, in the method of processing an optical element mold according to the second aspect, the clearance angle of the cutting edge of the tool is greater than the maximum tangent angle at the time of contact between the processed surface of the workpiece and the tool. It is large.

  The invention according to claim 4 holds the workpiece and is movable in the Z-axis direction substantially orthogonal to the machining surface of the workpiece and the Y-axis direction orthogonal to the Z-axis direction. In a processing apparatus having a workpiece holding part and a tool that is movable in the X-axis direction orthogonal to the Z-axis and the Y-axis and grinds the workpiece, when processing the workpiece, Simultaneously with the movement of the workpiece holding part in the Z-axis direction, control means is provided for moving the tool in the X-axis direction and then moving the workpiece holding part in the Y-axis direction. It is characterized by.

  According to a fifth aspect of the present invention, in the processing apparatus according to the fourth aspect, the control means moves the workpiece holding portion in the direction of the Z-axis and at the same time in a plane perpendicular to the Y-axis. The tool is rotated around the Y axis so that the tip of the tool draws an arcuate locus.

  According to the present invention, it is possible to form a recess having a small curvature radius.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a processing apparatus used for carrying out a method for processing an optical element mold according to one embodiment of the present invention, and FIG. 2 is a front view of a microlens mold created by the processing method.

  This processing apparatus includes a Z-axis slide 6, a Y-axis slide 7, an X-axis slide 5, and a B-axis rotary table 8.

  The machining apparatus according to this embodiment is, for example, an NC machining apparatus, and drives the Z-axis slide 6, the Y-axis slide 7, the X-axis slide 5, and the B-axis rotary table 8 according to instructions from an NC controller (control means) 10, for example. Control the start / stop and rotation speed of a motor (not shown), and move the Z-axis slide 6, Y-axis slide 7, X-axis slide 5 and B-axis rotary table 8 to any position determined by the program. Can do.

  The Z-axis slide 6 is disposed on a bed (not shown). The Z-axis slide 6 can move in the Z-axis direction on the bed. The position of the Z-axis slide 6 is detected by, for example, a laser interferometer (not shown), and the detection result is fed back to the NC controller 10.

  The Y-axis slide 7 is disposed on the Z-axis slide 6. The Y-axis slide 7 is movable in the Y-axis direction (height direction). The position of the Y-axis slide 7 is detected by, for example, a laser interferometer, and the detection result is fed back to the NC controller 10. A spindle spindle 9 is provided at the tip of the Y-axis slide 7 in the Z-axis direction.

  A workpiece 1A serving as a base material of a microlens mold (optical element mold) 1 (see FIG. 2) is fixed to a central portion (workpiece holding portion) of the spindle spindle 9 with a screw (not shown) or the like. Has been.

  The X-axis slide 5 is disposed adjacent to the Y-axis slide 7 on a bed (not shown). The X-axis slide 5 can move on the bed in the X-axis direction. The position of the X-axis slide 5 is detected by, for example, a laser interferometer, and the detection result is fed back to the NC controller 10.

  The B-axis rotary table 8 is disposed on the X-axis slide 5. The B-axis rotary table 8 can rotate about the Y axis orthogonal to the Z axis and the X axis as indicated by an arrow B. The rotation angle of the B-axis rotary table 8 is detected by a rotation angle detector (not shown), and the detection result is fed back to the NC controller 10.

  A diamond tool holder 4 for holding a diamond tool (tool) 3 is provided at the center of the B-axis rotary table 8. The diamond tool 3 is, for example, a single crystal diamond tool. The cutting edge of the diamond cutting tool 3 has a shape that does not interfere with anything other than the processing point of the workpiece 1A.

  The processing surface (XY surface) 2 of the workpiece 1A is cut using the diamond tool 3 to form a recess 2a corresponding to the lens shape of the microlens. The accuracy of the shape of the cutting edge 3-1 determines the accuracy of the shape of the microlens mold 1 as it is. Therefore, a diamond tool 3 having a high roundness accuracy of the cutting edge 3-1 is used, or a correction processing function is provided in the processing device to correct processing errors caused by meandering or thermal deformation of the slides 5, 6, and 7. It is necessary to have it. The correction processing function is a function of measuring the shape of the recess 2a after processing the processing surface 2, correcting the original processing program in consideration of the shape error, and trying to eliminate the processing error after the second time.

  When the diamond tool 3 is fixed to the diamond tool holder 4, the position of the diamond tool 3 in the height direction (Y-axis direction) coincides with the position of the center axis of the main spindle 9 in the height direction.

  Shaper processing using this processing apparatus includes simultaneous biaxial shaper processing and simultaneous triaxial shaper processing. The shaper processing is a processing method in which the workpiece 1A is fixed and the diamond tool 3 is moved.

  FIG. 3 is a diagram for explaining the shaper processing.

  First, simultaneous biaxial shaper processing will be described.

(1) Each slide so that the diamond cutting tool 3 is moved in the X-axis direction according to the radius of curvature of the concave portion 2a of the microlens mold 1 and at the same time, the workpiece 1A is moved in the Z-axis direction. The processing surface 2 of the workpiece 1A is cut by controlling the motor that drives the motors 5 and 6.

(2) After the workpiece 1A is cut by a predetermined amount, the Y-axis slide 7 is driven so that the workpiece 1A is moved in the Y-axis direction by a predetermined pitch without contacting the diamond tool 3. Control the motor.

(3) Similarly to (1), the diamond tool 3 is moved in the X-axis direction, and simultaneously with this movement, a motor that drives the slides 5 and 6 so as to move the workpiece 1A in the Z-axis direction. The processed surface 2 of the workpiece 1A is cut by control.

  Thereafter, the microlens mold 1 is created by repeating the steps (1) to (3).

  In this simultaneous biaxial shaper processing, it is necessary to make the clearance angle of the cutting edge 3-1 of the diamond cutting tool 3 larger than the maximum tangent angle at the time of contact between the processing surface 2 of the workpiece 1A and the diamond cutting tool 3.

  In the case of a single crystal diamond tool, it is very difficult to perform relief processing of 20 ° or more while maintaining the roundness of the cutting edge 3-1, due to the crystal orientation of the diamond, and the strength of the cutting edge 3-1 is reduced. Wear of the cutting edge 3-1 is accelerated. Therefore, when the maximum tangent angle exceeds 20 °, simultaneous three-axis shaper machining is preferable, in which not only movement in the X-axis and Z-axis directions but also rotation around the Y-axis is performed simultaneously.

  Next, simultaneous three-axis shaper processing will be described.

(1) The diamond cutting tool 3 is moved in the X-axis direction according to the radius of curvature of the concave portion 2a of the microlens mold 1, and simultaneously with this movement, the B-axis rotary table 8 is rotated around the Y-axis. The respective motors that drive the shaft slide 5 and the B-axis rotary table 8 are controlled, and the motor that drives the Z-axis slide 6 is simultaneously activated to cut the machining surface 2 of the workpiece 1A.

(2) After the workpiece 1A is cut by a predetermined amount, the Y-axis slide 7 is driven so that the workpiece 1A is moved in the Y-axis direction by a predetermined pitch without contacting the diamond tool 3. Control the motor.

(3) Similar to (1), the diamond bit 3 is moved in the X-axis direction, and in parallel with this movement, the X-axis slide 5 and the B-axis are rotated so that the B-axis rotary table is rotated around the Y axis. The respective motors that drive the table 8 are controlled, and the motor that drives the Z-axis slide 6 is simultaneously activated to cut the machining surface 2 of the workpiece 1A.

  Thereafter, the microlens mold 1 is created by repeating the steps (1) to (3).

  The present inventor conducted the following experiment in order to obtain data of the die machining result.

  As a material of the microlens mold 1, a workpiece 1A obtained by applying Ni-P (electroless nickel plating) to Starbucks (13Cr stainless steel manufactured by Woodeholm) was used. A so-called four-eye microlens mold 1 having a recess 2a radius and depth of 8 mm and 0.25 mm, respectively, was prepared.

  Hereinafter, the processing results are described together with the processing conditions.

Processing conditions: Single crystal diamond tool, radius 1mm
2. Finish feed rate X axis, Z axis 100mm / min
B axis 3rpm
3. Finish cut depth 2μm
4). Finishing pitch (Y axis direction) 8μm
5. Cutting oil White kerosene
6). Processing time 100 minutes Processing result: 1. Surface roughness 6.7NmRa (theoretical surface roughness (finishing pitch) ^2/8 * (edge radius)) = 8NmRa)
2. Swell 0.06nmRa
3. As 0.14 μm
4). Shape accuracy 0.1μm
5. Position accuracy (positional relationship between recesses) 0.5 μm or less.

  According to this embodiment, since the method of cutting the workpiece with the diamond cutting tool is different from the conventional example as described above, there is no problem such as interference between the spindle to which the diamond cutting tool is attached and the workpiece (workpiece), and the radius of curvature is reduced. Can be formed. Moreover, higher surface accuracy than the fly-cut method can be obtained from the above processing results. Furthermore, the positional accuracy can be increased to the submicron unit from the processing result.

FIG. 1 is a perspective view of a processing apparatus used for carrying out an optical element mold processing method according to an embodiment of the present invention. FIG. 2 is a front view of a microlens mold created by the processing method. FIG. 3 is a diagram for explaining the shaper processing.

Explanation of symbols

  1: Micro lens mold (optical element mold), 1A: work piece, 2: processing surface, 3: diamond tool (tool), 3-1: cutting edge, 5: X-axis slide, 6: Z-axis slide, 7: Y-axis slide, 8: B-axis rotary table, 10: NC controller (control means).

Claims (5)

In a processing method for forming a mold for forming an optical element having a plurality of independent optical functional surfaces by processing using a tool for cutting a workpiece,
Movement of the workpiece in the direction of the Z axis perpendicular to the machining surface of the workpiece, movement of the tool in the direction of the X axis perpendicular to the Z axis on the horizontal plane, and the Z axis And a machining step of machining the workpiece by simultaneously performing rotation of the tool about the Y axis perpendicular to the X axis;
A method of processing an optical element mold, comprising repeatedly performing a moving step of moving the workpiece relative to the tool in the Y-axis direction. In a processing method for forming a mold for forming an optical element having a plurality of independent optical functional surfaces by processing using a tool for cutting a workpiece,
The movement of the workpiece in the direction of the Z axis perpendicular to the machining surface of the workpiece and the movement of the tool in the direction of the X axis perpendicular to the Z axis on the horizontal plane are performed simultaneously. A processing step of processing the workpiece;
A method of processing an optical element mold, comprising repeatedly performing a moving step of moving the workpiece relative to the tool in a direction of the Y axis perpendicular to the Z axis and the X axis.   3. The method of processing an optical element mold according to claim 2, wherein a clearance angle of the cutting edge of the tool is larger than a maximum tangent angle at the time of contact between the processing surface of the workpiece and the tool. A workpiece holding section that holds the workpiece and is movable in a Z-axis direction substantially orthogonal to the processing surface of the workpiece and a Y-axis direction orthogonal to the Z-axis direction; In a processing apparatus having a tool capable of moving in the direction of the X axis perpendicular to the Z axis and the Y axis, and grinding the workpiece,
During the processing of the workpiece, the tool is moved in the X-axis direction simultaneously with the movement of the workpiece holding portion in the Z-axis direction, and then the workpiece holding portion is moved in the Y-axis direction. A processing apparatus comprising control means for moving in a direction.   The control means moves the workpiece holding portion in the Z-axis direction and simultaneously moves the tool so that the tip of the tool draws an arc-shaped locus in a plane orthogonal to the Y-axis. The processing apparatus according to claim 4, wherein the processing apparatus is rotated about the Y axis.

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