JP2004202667A - Method of generating shape of grindstone for grinding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of generating the shape of a grindstone for grinding, which generates a ground surface at a desired curvature and with high profile irregularity. <P>SOLUTION: According to the method, the grindstone 4 for grinding, having an abrasive grain layer on the periphery of a rotating shaft and a columnar grindstone 8 for generating the shape, which has its rotating shaft located in a plane perpendicular to the former rotating shaft and has a hollow tip portion, are arranged such that the rotating shaft of the grindstone 4 for grinding and the rotating shaft of the grindstone 8 for generating the shape are twisted with respect to each other. Then while the grindstone 4 for grinding and the grindstone 8 for generating the shape are rotated on the respective rotating shafts, the tip of the grindstone 8 for generating the shape is abutted on a side surface of the grindstone 4 for grinding, to thereby generate the shape of the grindstone 4 for grinding. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a grinding wheel suitable for grinding an optical surface of an optical element such as a lens, a mirror, or a prism, or a grinding surface of a mold surface for forming the optical surface by press molding. And a method of creating the shape of
[0002]
[Prior art]
At present, with the advance of digital image processing technology of digital cameras and the like, higher precision of optical elements such as lenses, mirrors, and prisms is required.
Conventionally, in the grinding of the optical surface of an aspherical optical element, or in the grinding of the molding surface of a mold for press-molding the optical surface, the workpiece to be ground is rotated around the optical axis. By rotating the grinding wheel so that the grinding wheel surface is at a constant speed around the grinding wheel axis and scanning the workpiece to be ground or the grinding wheel in a certain direction, the surface to be ground has a desired shape. Processing was done to become. In this case, the actual processing locus of the grinding wheel moves spirally on the surface of the workpiece.
[0003]
The invention described in Patent Document 1 is a method for creating a shape of a grindstone used for grinding an optical surface of an optical element having an aspherical surface or a grinding surface of a mold for press-molding the optical surface. Is disclosed. Hereinafter, the present invention will be described with reference to FIG.
[0004]
As shown in FIG. 9 (a), the grinding wheel 108 is arranged so that the grinding wheel rotation axis AA of the grinding wheel 108 and the grinding wheel rotation axis BB of the grinding wheel 104 intersect. The wheel 104 and the shape creating grindstone 108 are relatively close to each other while rotating. Then, when the tip 108a of the grinding wheel 108 for forming a shape and the grinding surface 104a of the grinding wheel 104 are cut in line contact with each other, the grinding surface 104a of the grinding wheel 104 can be formed into a spherical shape. 9B is a diagram of the grinding wheel 104 and the shape creating wheel 108 shown in FIG. 9A as viewed from the left side in FIG. 9A.
[0005]
If the spherical grinding wheel formed in this way is used, regardless of whether the surface to be ground such as the optical surface of the optical element or the molding surface of the mold is convex or concave, or shallow or Regardless of whether it is a deep surface or not, whether or not there is an inflection point, the grinding position of the grinding wheel and the grinding position of the surface to be ground can always be brought into vertical contact, so grinding can be performed. There is an advantage that processing can be performed regardless of the shape of the processing surface.
[0006]
[Patent Document 1]
JP 2001-260023 A
[Problems to be solved by the invention]
For example, when the surface to be ground has an axisymmetric aspherical convex surface and does not have an inflection point and is processed with a spherical grinding wheel, the grinding surface and the grinding wheel are used. The center position of the curvature is on the opposite electrode side, and grinding is performed away from the center position of the curvature. When grinding is performed as described above to obtain a desired shape in this state, the curvature of the grinding wheel for the depth of cut in the direction perpendicular to the trajectory direction of the grinding wheel on the surface to be ground is increased. Since the transfer is performed, a wave-shaped roughness is generated on the surface to be ground. In addition, since the grinding wheel and the center of curvature of the surface to be ground are separated from each other, the scanning distance is long because the grinding wheel is scanned so as to go around the surface to be ground. The lead time will be longer.
[0008]
A similar problem also occurs when, for example, the surface to be ground is processed with a spherical grinding wheel for forming a shallow concave surface with an axisymmetric aspheric surface.
In order to cope with such a problem, it has been demanded to be able to create a grinding wheel having a free shape in addition to a simple spherical shape.
[0009]
The problem to be solved by the present invention is to provide a method for creating a shape of a grinding wheel for grinding capable of creating a ground surface with a desired curvature with high surface accuracy in view of the above-mentioned demands. .
[0010]
[Means for Solving the Problems]
A method for creating a shape of a grinding wheel for grinding, which is one aspect of the present invention, includes a grinding wheel having an abrasive layer on an outer peripheral portion of a rotating shaft, and a rotating wheel on a surface perpendicular to the rotating shaft. An axis is located and the tip is hollow and a cylindrical shape creating grindstone is arranged such that the rotation axis of the grinding wheel and the rotation axis of the shape creation grindstone are in a twisted position, The grinding wheel for grinding is applied by applying the tip of the grinding wheel for shape creation to the side surface of the grinding wheel for grinding while rotating the grinding wheel for grinding and the grinding wheel for shape creation each around its own rotation axis. The above-mentioned problem is solved by creating the shape of.
[0011]
By doing so, it is possible to create a grinding wheel having a free shape with a high surface accuracy without being limited to a simple spherical shape.
In the above-described method for creating a shape of a grinding wheel according to the present invention, the rotation axis of the grinding wheel is located at a position separated from the rotation axis of the shape creation wheel by a radius of the shape creation wheel. It can be arranged at the position closer to the sum of the radius of the grinding wheel and the radius of the shape creating wheel.
[0012]
By doing so, the ground surface of the grinding wheel can be formed into a concave shape having a desired curvature with high surface accuracy.
In the above-described method for creating a shape of a grinding wheel according to the present invention, the rotation axis of the grinding wheel is disposed at a position closer to the radius of the shape creation wheel from the rotation axis of the shape creation wheel. You can do so.
[0013]
By doing so, the grinding surface of the grinding wheel can be formed into a convex shape having a desired curvature with high surface accuracy.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the rotation axis of the grinding wheel and the rotation axis of the shape creation wheel are arranged at a twist position where they do not intersect, and the grinding wheel is rotated at that position and the shape creation wheel is also rotated. Let it. Then, in this state, by bringing the grinding wheel for grinding or the grinding wheel for shape creation close to and in contact with the surface, the grinding surface of the grinding wheel for grinding is formed into a desired curvature regardless of the concave convex surface and the deep shallow surface, and Creates a ground surface with high surface accuracy.
[0015]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Example 1]
First, the configuration of the first embodiment will be described.
FIG. 1 shows a configuration of a processing machine for processing a grindstone into an object for grinding an axisymmetric aspheric lens. This processing machine has an axis configuration in which the moving axis can be controlled in three orthogonal directions of an X axis, a Y axis, and a Z axis which are respectively orthogonal to each other as shown in FIG.
[0016]
The spindle 1 is held on a Z-axis table 2 that can be moved in the Z-axis direction, and the rotation axis A of the spindle 1 can be rotated by the spindle motor 3 about the Z-axis direction.
A tool motor 5 for rotating the grinding wheel 4 is held on an XY-axis table 6 that can be moved in the X-axis direction and the Y-axis direction.
[0017]
The tool motor 5 is arranged so that its rotation axis B rotates around the Y-axis direction orthogonal to the above-described main spindle rotation axis A. The tip of the tool motor 5 holds a grinding wheel 4 to which a tool shaft 10 is adhered. By operating the tool motor 5, the grinding wheel 4 is centered on the tool rotation axis B described above. Rotate.
[0018]
FIG. 2 shows the structure of the grinding wheel 4 created in the first embodiment.
As shown in FIG. 2, the grinding wheel 4 is provided with a thick abrasive layer 9 on the outer periphery of the grinding wheel shaft. In the present embodiment, the grinding surface 4a on the side surface of the grinding wheel shaft of the grinding wheel 4 is formed in a flat or concave shape. In the figure, T is the radius of the top of the concave surface of the grinding surface of the grinding wheel 4, and C is the axis at which the center of curvature of the concave portion of the grinding surface 4 a exists (curvature center position axis). And R is the radius of curvature of the concave portion of the ground surface 4a.
[0019]
Returning to the description of FIG. 1, the tip of the main spindle 1 holds a shape-creating grindstone 8 via a chuck device 7. At this time, the grinding wheel 8 for forming a shape is rotated around the spindle rotation axis A by operating the spindle motor 3. FIG. 3 shows the structure of the grinding wheel 8 for creating a shape.
[0020]
As shown in FIG. 3, the shape creating grindstone 8 has a hollow cylindrical cup shape, and diamond abrasive grains 8a are provided at the tip of the cup. In the drawing, S is the radius of the shape creating grindstone 8 and U is the radius of the inner diameter of the shape creating grindstone 8.
[0021]
Hereinafter, a method of creating the shape of the grinding wheel 4 in the first embodiment will be described with reference to FIGS. 4 and 5. 4 shows the grinding wheel 4 and the shape creating wheel 8 from the front side in the processing machine shown in FIG. 1, and FIG. 5 shows the grinding wheel from the top side in the processing machine shown in FIG. FIG. 4 is a view of a processing grindstone 4 and a shape creation grindstone 8.
[0022]
First, the XY-axis table 6 of the processing machine shown in FIG. 1 is moved in the Y-axis direction, and the height of the curvature center position axis C of the concave portion of the grinding surface 4a coincides with the height of the above-described main spindle rotation axis A ( It is set so that the positions in the Y-axis direction coincide (see FIG. 4).
Next, the XY-axis table 6 is moved in the X-axis direction this time, and the tool rotation axis B for rotating the grinding wheel 4 is at least separated from the position of the spindle rotation axis A by at least the radius S of the shape creation grinding wheel 8. The torsion position is set to a position that is a distance up to the sum of the radius T of the grinding wheel 4 for grinding and the radius S of the grinding wheel 8 for shape creation.
[0023]
Next, the spindle motor 3 and the tool motor 5 are operated to rotate the grinding wheel 4 and the shape creating wheel 8. Then, in this state, the Z-axis table 2 is moved and fed so that the grinding wheel 4 and the shape creating wheel 8 are relatively close to each other. When this moving feed is continued, the grinding surface 4a of the grinding wheel 4 and the outer peripheral portion of the cup portion of the shape creating grinding wheel 8 come into line contact with each other. When the Z-axis table 2 is further moved and fed, the line contact portion of the grinding surface 4a is cut by the diamond abrasive grains 8a. Thereafter, the moving feed of the Z-axis table 2 is continued until the entire grinding surface 4a of the grinding wheel 4 is cut so that the grinding surface 4a of the grinding wheel 4 is formed into a concave shape with high surface accuracy. It can be created.
[0024]
Here, since the height of the center position axis C and the height of the main spindle rotation axis A are matched, the center of curvature of the concave shape of the grinding wheel 4 is on the main spindle rotation axis A. Therefore, when the distance between the spindle rotation axis A and the tool rotation axis B is L, the radius of curvature R of the concave shape of the grinding surface 4a of the grinding wheel 4 is calculated using the L and the above-described S and T. What can be expressed by the equation is apparent with reference to FIG.
[0025]
R = T × {S / (LS)}
By setting each parameter in accordance with the above formula, it is possible to create a grinding wheel 4 with high surface accuracy, in which the grinding surface 4a has a concave shape with a desired curvature.
[Example 2]
Next, a second embodiment will be described. It should be noted that also in the second embodiment, the grindstone is processed using the same processing machine as that shown in FIG. Also, the shape creating grindstone 8 having the structure shown in FIG. 3 is used.
[0026]
Note that the reference numerals attached to the respective drawings are used in common, and description thereof is omitted. First, FIG. 6 will be described. FIG. 2 shows the structure of the grinding wheel 4 created in the second embodiment.
As shown in FIG. 6, the grinding wheel 4 is provided with a thick abrasive layer 9 on the outer periphery of the grinding wheel shaft. In the present embodiment, the grinding surface 4a on the side of the grinding wheel shaft of the grinding wheel 4 is formed in a convex shape. In the figure, V is the radius of the top of the convex shape of the grinding surface of the grinding wheel 4 for grinding, and C is the axis at which the center of curvature of the convex portion of the grinding surface 4a exists (curvature center position axis). And R is the radius of curvature of the convex portion of the ground surface 4a.
[0027]
Hereinafter, a method of creating the shape of the grinding wheel 4 in the second embodiment will be described with reference to FIGS. 7 and 8. FIG. 7 is a view of the grinding wheel 4 and the shape creating wheel 8 from the front side of the processing machine shown in FIG. 1, and FIG. 8 is a diagram showing the grinding wheel from the top side of the processing machine shown in FIG. FIG. 4 is a view of a processing grindstone 4 and a shape creation grindstone 8.
[0028]
First, the XY-axis table 6 of the processing machine shown in FIG. 1 is moved in the Y-axis direction, and the height of the curvature center position axis C of the convex portion of the grinding surface 4a of the grinding wheel 4 and the above-described spindle rotation axis A Is set so as to match the height (the position in the Y-axis direction matches) (see FIG. 7).
[0029]
Next, the XY-axis table 6 is moved in the X-axis direction this time, and the tool rotation axis B for rotating the grinding wheel 4 is at least the radius U of the inner diameter of the shape creation grinding wheel 8 from the position of the main shaft rotation axis A. Set so that the position is close to the twist.
Next, the spindle motor 3 and the tool motor 5 are operated to rotate the grinding wheel 4 and the shape creating wheel 8. Then, in this state, the Z-axis table 2 is moved and fed so that the grinding wheel 4 and the shape creating wheel 8 are relatively close to each other. When this moving feed is continued, the grinding surface 4a of the grinding wheel 4 and the inner peripheral portion of the cup portion of the shape creating grinding wheel 8 eventually come into line contact. When the Z-axis table 2 is further moved and fed, the line contact portion of the grinding surface 4a is cut by the diamond abrasive grains 8a. Thereafter, the moving feed of the Z-axis table 2 is continued until the entire surface of the grinding surface 4a of the grinding wheel 4 is cut so that the grinding surface 4a of the grinding wheel 4 has a convex shape with high surface accuracy. It can be created.
[0030]
Here, since the height of the center position axis C and the height of the main spindle rotation axis A are matched, the center of curvature of the convex shape of the grinding wheel 4 is on the main spindle rotation axis A. Therefore, assuming that the distance L between the main spindle rotation axis A and the tool rotation axis B is, the radius of curvature R of the convex shape of the grinding surface 4a of the grinding wheel 4 is represented by the following equation using this L and U and V described above. Can be clearly understood with reference to FIG.
[0031]
R = V × {U / (UL)}
By setting each parameter in accordance with the above formula, it is possible to create a grinding wheel 4 for grinding with high surface accuracy, in which the grinding surface 4a has a convex shape with a desired curvature.
[0032]
In addition, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.
[0033]
【The invention's effect】
As described above in detail, according to the present invention, the grinding of an optical surface of an optical element, or the grinding of a molding surface of a mold for forming the optical surface by press molding, etc. There is an effect that the shape of the grinding surface of the grindstone can be formed with a high surface accuracy with a desired curvature regardless of the concave convex surface or the deep shallow surface.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a processing machine.
FIG. 2 is a view showing the structure of a grinding wheel created in Example 1.
FIG. 3 is a view showing a structure of a shape creating whetstone.
FIG. 4 is a view (No. 1) for explaining a method of creating a shape of a grinding wheel in Example 1;
FIG. 5 is a diagram (part 2) for explaining the method of creating the shape of the grinding wheel in the first embodiment.
FIG. 6 is a view showing the structure of a grinding wheel created in Example 2.
FIG. 7 is a view (No. 1) for explaining a method of creating a shape of a grinding wheel in Example 2;
FIG. 8 is a diagram (part 2) for explaining the method of creating the shape of the grinding wheel in the second embodiment.
FIG. 9 is a diagram illustrating a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Spindle 2 Z-axis table 3 Spindle motor 4 Grinding wheel 4a Grinding surface 5 Tool motor 6 XY-axis table 7 Chuck device 8 Shape creation grinding wheel 8a Diamond abrasive grains 9 Abrasive layer 10 Tool shaft 104 Grinding wheel 104a Grinding surface 108 Shape creation whetstone 108a Tip

Claims (3)

A grinding wheel having an abrasive layer on the outer periphery of a rotating shaft, and a cylindrical grinding wheel having a hollow tip where the rotating shaft is positioned on a plane perpendicular to the rotating shaft. And arranged such that the rotation axis of the grinding wheel and the rotation axis of the shape creation grinding wheel are at the position of the twist,
The grinding wheel for grinding is formed by applying the tip of the grinding wheel for shape creation to the side surface of the grinding wheel for grinding while rotating the grinding wheel and the shape creating wheel each around its own rotation axis. Creating the shape of
A method for creating a shape of a grinding wheel for grinding. The rotation axis of the grinding wheel is located at a position farther than the radius of the shape creation wheel from the rotation axis of the shape creation wheel, the radius of the grinding wheel and the radius of the shape creation wheel. The method according to claim 1, wherein the grinding wheel is arranged at the position closer to the sum of The rotating shaft of the grinding wheel for grinding according to claim 1, wherein the rotating shaft of the grinding wheel for grinding is arranged at a position closer to a radius of the grinding wheel for shape creation from the rotating shaft of the grinding wheel for shape creating. Shape creation method.

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