JPH038901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention allows the tip of a first slider sliding along the longitudinal direction of a first guide pivoted at the center of an approximate circle of an aspherical surface to draw an aspherical trajectory; An optical aspherical surface, characterized in that a second slider pivotally connected to the surface is positioned in the normal direction of the machined surface, and the positional fluctuation of the second slider is directly applied to the tool to form the optical aspherical surface. It concerns the creation method.

As is well known, in the field of optical technology and other technical fields, there is a high demand for aspheric lenses, aspheric mirrors, and the like.

The conventional method for creating an optical aspherical surface is shown in Figure 1a.
As shown in the figure, on the surface of the workpiece 1 rotating at high speed,
There is a method of forming the workpiece by bringing the tip 3 of the tool 2 rotating at high speed into contact with the workpiece and moving the tool 2 in the radial direction of the workpiece. In this case, the movement locus of the tip 3 of the tool 2 has an aspherical shape, and the movement locus of the tool is divided into the X-axis direction along the optical axis of the workpiece 1 and the Y-axis perpendicular to the X-axis direction. The direction must be controlled with high precision. Therefore, in control in both axial directions, the range in which the tool 2 moves is wide and errors are likely to occur, and it is difficult to obtain an aspheric surface with a preset shape.

Also, the tool 2 is positioned parallel to the X-axis direction and moves in the Y-axis direction (radial direction), but in this case, a part of the tip 3 of the tool 2 touches the machining surface 1' of the workpiece 1. Contact. If the tool 2 is moved in this state, a fine waveform will be formed on the machined surface 1' depending on the amount of feed of the tool 2 per rotation of the workpiece 1, so that a highly accurate aspherical surface will not be obtained.

In addition, Fig. 1b shows the case of machining an aspherical surface by always aligning the tool 2 with the normal direction of the approximate circle (circumcircle in the case shown) of the machining surface 1'. Since there is a difference Δr between 1' and the approximate circle a, a fine waveform still occurs and high precision cannot be obtained.

The present invention was proposed in view of the above, and is an aspherical surface creation method in which the aspherical surface is processed by bringing the tip of a tool into contact with the processing surface of a rotating workpiece.
Assuming a virtual workpiece that is the same or similar in shape to the target workpiece, a first slider that can freely slide along the length direction is placed at the center of a circle that approximates the virtual machining surface of the virtual workpiece. A first guide is rotatably provided, the tip of a second slider is pivotally connected to the lower part of the first slider, the second slider is slidably supported by the second guide, and the virtual A first cam whose outer periphery is formed into an aspherical shape of a virtual workpiece is provided at the center of a circle that approximates the machining surface, and a roller provided at an upper portion of the first slider faces the first cam; 1st guide and 1st guide
The slider is made to follow the first cam so that the movement locus drawn by the pivot points of both sliders matches the virtual machining surface of the virtual workpiece, and the second guide is aligned with the normal to the virtual machining surface. A second cam positioned in the direction is faced, and the tip of the tool for cutting the workpiece is made to correspond to the pivot point, and a coupling mechanism is interposed between the second guide and the tool to move the tool to the second cam. By moving the second slider in the same state as the first cam, the surface of the workpiece is processed into the aspherical shape of the first cam.

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

FIG. 2 is a schematic explanatory diagram of the present invention, and shows a case where an aspherical convex lens is created as the workpiece 11. A workpiece 11 is placed on a rotating turntable 12, and a tip 15 of a tool 14 is brought into contact with a processing surface 13 of the workpiece 11. The tip 15 is a hollow cylindrical diamond grindstone, fly cutter, or the like. If this tool 14 is rotated at high speed and moved in the radial direction of the workpiece 11 while always being positioned in the normal direction to the machined surface 13, the tip 15 of the tool 14 will turn the machined surface 13 into an aspherical surface. Can be processed. In this case, tool 1
4 is positioned in the normal direction of the machining surface 13 in order to improve machining accuracy by keeping the entire surface of the tip 15 in constant contact with the machining surface 13. Further, when the tool 14 moves along the radial direction of the workpiece 11, the aspherical shape of the machined surface 13 can be changed by changing the position along the length direction of the tool 14. That is, when the tool 14 is lowered in the length direction, the tip 1
The cutting allowance of the machined surface 13 by the tip 15 becomes large, and conversely, if the tool 14 is not lowered too much in the length direction, the cutting allowance of the machined surface 13 by the tip 15 becomes small.

Therefore, the direction and position of the tip 15, in other words, the direction and position of the tool 14 are factors in creating a highly accurate aspherical surface, and if these factors are controlled with high precision, the tip of the tool 14 The portion 15 allows the processing surface 13 to be processed into a desired aspherical surface with high precision.

Therefore, in the present invention, in order to control the direction and position of the tool 14, a control means 16 for detecting and setting the virtual machining surface 13' is provided. This control means 16 has a first guide 17, a second guide 21, and the like. Furthermore, in the present invention, assuming a virtual workpiece 11' having the same or similar shape to the target workpiece 11, a virtual approximation circle a (see FIG. In this case, the first guide 17 is pivoted to the center O of the circumscribed circle
The guide 17 can be rotated by an angle θ1 with respect to the X-axis direction (optical axis direction) of the virtual workpiece 11'.

The first guide 17 described above is a thin cylindrical or groove-shaped member that extends from the center O in the radial direction of the virtual approximate circle a. 1 slider 18 is provided. A distal end portion 20 of a second slider 19 supported slidably in the length direction of a second guide 21 is pivotally attached to the lower portion of the first slider 18 . The second slider is the pivot point 2 of the tip 20.
2 as a fulcrum, it can rotate by an angle θ2 with respect to the X-axis direction of the virtual workpiece 11', and θ2 is set from 0 degrees to 90 degrees.

Then, the second slider 19 described above and the tool 14 for cutting the processing surface 13 of the workpiece 11 are connected by a coupling mechanism 23. This coupling mechanism 23 is an electrical, mechanical, and optical device, and the second slider 19
The position and direction of the virtual workpiece 11' are directly transmitted to the tool 14 so that the coordinates of the second slider 19 are at the same position and in the same direction.
3', the tool 14 can also be moved in the same state.

Therefore, the pivot point 22 of the tip 20 of the second slider 19 is set at the same coordinate position as the tip 15 of the tool 14, and the movement locus drawn by the pivot point 22 is set to the virtual workpiece 11'. By matching the shape of the machining surface 13', that is, the pivot point 22 is aligned with the shape of the virtual workpiece 11'.
If the tool 14 is moved along the machining surface 13' of
The movement trajectory drawn by the tip 15 of the virtual machining surface 13'
It can be made into the same shape. In this case, by rotating the first guide 17 using the center O as a fulcrum, the position of the pivot point 22 in the Y-axis direction is set,
Furthermore, by sliding the first slider 18 in the length direction of the first guide 17, the position of the pivot point 22 in the X-axis direction is set. Furthermore, the second slider 19
By rotating the slider at the pivot point 22, the second slider can be positioned in the normal direction of the virtual machining surface 13'.

In the relationship between the control means 16 and the tool 14 as described above, when the workpiece 11 and the tool 14 are rotated at high speed, the tip 15 of the tool 14 follows the same trajectory as the pivot point 22, and the workpiece 11 The machined surface 13 can be processed to have the same shape as the virtual machined surface 13'. Further, since the tool 14 always faces in the normal direction to the processing surface 13, the processing surface 13 can be processed using the entire surface of the tip portion 15, making it possible to perform highly accurate processing.

The above explanation is for the case where the workpiece 11 is an aspherical convex lens, but as shown in FIG. 3, when the aspherical surface is a concave surface, processing can be performed in almost the same way as above. That is, in the case of a concave surface, the virtual workpiece 1
The center O of a virtual approximation circle a that approximates the virtual processing surface 13' of 1' is located above the virtual processing surface 13'. Therefore, the first guide 17 is pivotally attached to the fulcrum O in the middle of its length, and the position of the first slider 18 is adjusted in the length direction while changing both sliders 18 and 19 to desired angles. The point 22 can be made to coincide with the locus of the virtual machined surface 13'. Furthermore, if the position, direction, movement state, etc. of the second slider are transmitted to the tool 14 through the coupling mechanism 23, the tip end 15 of the tool 14 will be in the same state as the pivot point 22, and the machining surface 13 of the workpiece 11 will be virtually machined. It can be processed to have the same shape as surface 13'.

Note that the symbols not explained in FIG. 3 have the same configuration as the same symbols in the explanation of FIG.

Next, FIG. 4 shows a preferred example for carrying out the present invention. This figure shows the case where the workpiece 11 is a convex lens, and the first guide 17 is located at the center O of the virtual approximation circle a that approximates the virtual workpiece 11'.
The lower part of the gear 24 and the first gear 24 are integrally provided so as to be rotatable. A second gear 25 meshes with the first gear 24, and a third gear 26, which is coaxial with the second gear 25, meshes with a fourth gear 27, which is coaxial with the first gear 24 and can rotate freely. This fourth gear 27 is coaxially provided with a first cam 28 whose outer peripheral edge is formed multiple times (for example, 100 times) the aspherical shape of the virtual workpiece 11'. Since the second gear 25, the third gear 26, and the fourth gear 27 are a gear group for increasing speed, the rotation of the first gear 24, which is rotated by a drive source such as a motor, is accelerated and the first cam 2
8. Further, a fifth gear 29 for speed increase is meshed with the first gear 24, and the fifth gear 29 is engaged with the first gear 24.
The second cam 3 is coaxial with the sixth gear 30 that meshes with the gear 9.
1 will be provided. Therefore, when the first gear 24 rotates, the speed increases and the first cam 28 and the second cam 31 rotate.

The first guide 17 is provided with a first slider 18' and a third slider 32 on a straight line so as to be slidable in the length direction. The combination of the first slider 18' and the third slider 32 in FIG. 4 corresponds to the first slider 18 in FIG. 2. The tip 20 of the second slider 19 is pivotally attached to the lower part of the third slider 32, and the pivot point 22 between the third slider 32 and the tip 20 is connected to the virtual machining surface 13' of the virtual workpiece 11'. It is made to match. Further, a roller 33 facing the upper surface of the first cam 28 is provided at the upper end of the first slider 18', and a roller 33 facing the outer surface of the second cam 31 is provided on the second guide 21 that slidably supports the second slider 19. A roller 34 is provided.

A reduction mechanism 35 is interposed between the first slider 18' and the third slider 32. This reduction mechanism 35 is for restoring the first cam 28, which is multiple times larger than the virtual workpiece 11', to its original size. Lever 37 and third slider 32
The first lever 37 is swingable about a fulcrum 36 near the tip, and the second lever 39 is swingable about a fulcrum 38 near the base end. . Then, the tips of both levers 37 and 39 are connected. If the lever ratio of both levers 37 and 39 of this reduction mechanism 35 is set to 10:1, the overall reduction can be reduced to 1/100, and the sliding amount of the first slider 18' can be reduced to 1/100. 1
and can be transmitted to the third slider 32.

FIG. 5 shows an operational system diagram of the control means 16 described above. When the first gear 24 is rotated by the drive of the motor M, the first guide 17 rotates at a low speed about the center O as a fulcrum. Further, the rotation of the first gear 24 causes the first cam 28 to rotate via the second gear 25, third gear 26, and fourth gear 27, and the first cam 28
8 by the roller 33 facing the first slider 18'
slides inside the first guide 17, the first lever 37 is tilted at the fulcrum 36, the second lever 39 connected to this first lever 37 is tilted at the fulcrum 38, and the second lever 37 is tilted at the fulcrum 38.
The third slider 32 connected to the lever 39 is supported by the first guide 17 and slides. Then,
The third slider 32 slides along the virtual machining surface 13'. By sliding this third slider 32, the vertical position of the pivot point 22 can be set.

On the other hand, the rotation of the first gear 24 is caused by the rotation of the fifth gear 2.
9. The rotation is transmitted to the sixth gear 30 to rotate the second cam 31, the second guide 21 is tilted by the roller 34, and the direction of the second slider 19 is determined.
Due to the shape of the second cam 31, the direction of the second slider 19 is set so that it always faces the normal direction to the virtual machining surface 13'.

In short, the first cam 28 is the third slider 32
The second cam 31 is used to set the position of the pivot point 22 between the second slider 19 and the second slider 19, and the second cam 31 is used to set the direction of the second slider 19. These settings can be made as appropriate depending on the shape of the gear train and cam.

The direction and position of the second slider 19 described above are detected by a coupling mechanism 23 consisting of optical, electrical, or mechanical means, and the tool 14
can be conveyed to. In addition, the tool 14 is attached to the air turbine 4.
0, etc., and the tool 14 is brought into contact with the workpiece 11 rotated by the motor 41. Therefore, since the movement state of the pivot point 22 is directly transmitted to the tool 14, the workpiece 11 can be processed with high precision into the same shape as the virtual workpiece 11'.

Although the above explanation is for the case where the workpiece 11 is a convex lens, a concave lens can be processed in exactly the same manner. By changing the shapes of the first cam 28 and the second cam 31 and selecting the gear train appropriately, it is possible to create an aspheric surface of any shape, and it can be applied not only to lenses but also to mirror surface creation. Can be done.

In summary, according to the present invention, the position and direction of the first slider for detecting and setting the shape of the virtual machined surface are controlled by following the first cam, and the second slider is always positioned in the normal direction of the aspherical surface. By doing so, the entire tip of the tool interlocked with the second slider can be brought into contact with the machined surface, making it possible to create a highly accurate aspherical surface.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, FIG. 1 a and b are schematic explanatory diagrams of the conventional aspherical surface generation method, FIG. 2 is a schematic explanatory diagram of the present invention, and FIG. 3 is a schematic illustration of another example of the present invention. 4 is a partial sectional view showing a specific mechanism, and FIG. 5 is an operational system diagram of FIG. 4. 11... Workpiece, 13... Machining surface, 14...
Tool, 15... Tip, 17... First guide, 1
8...First slider, 19...Second slider, 21...Second guide, 22...Pivot point, 28
...First cam, 31...Second cam, 33...Roller.

Claims (1)

[Claims] 1 In the aspherical surface creation method, which involves machining an aspherical surface by bringing the tip of a tool into contact with the machining surface of a rotating workpiece, a virtual workpiece that is the same or similar to the target workpiece is assumed. , a first guide having a first slider that is slidable along the length direction is rotatably provided at the center of a circle that approximates the virtual machining surface of the virtual workpiece, and a lower portion of the first slider is rotatably provided. The tip of the second slider is pivotally attached to the
The second slider is slidably supported by a second guide, and the outer peripheral edge is formed in the aspherical shape of the virtual workpiece at the center of a circle approximating the virtual workpiece surface.
A cam is provided, the first cam faces a roller provided above the first slider, the first guide and the first slider are made to follow the first cam, and the pivot point of both sliders is drawn. The movement locus is made to match the virtual machining surface of the virtual workpiece, and a second cam that positions the second guide in the normal direction of the virtual machining surface faces the second guide, and the workpiece is cut. The tip of the tool corresponds to the pivot point,
By interposing a coupling mechanism between the second guide and the tool and moving the tool in the same state as the second slider, the machined surface of the workpiece is processed into the aspherical shape of the first cam. A method for creating optical aspheric surfaces characterized by the following.