JPH0691506A - Spherical body grinding device - Google Patents

Abstract

PURPOSE:To provide a spherical body grinding device for improving the sphericity of the surface of a spherical body to be worked and the grinding efficiency. CONSTITUTION:An annular guide groove 12 which guides a spherical body 13 to be worked rotatably in the circumferential direction is provided on either one of two panel bodies 10 and 11 as a grinding tool. When the spherical body 13 to be worked is revolved on the periphery of the guide groove 12, the cross- section of the guide groove 12 is varied continuously in the direction of the panel bodies 10 and 11 so that the contact point of the guide groove 12 with the spherical body 13 to be worked is varied periodically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sphere grinding device for grinding (polishing) the surface of a sphere to be processed into a spherical shape.

[0002]

2. Description of the Related Art As a conventional spherical grinding device, for example, Japanese Patent Laid-Open No. 2-27971 is known. This is shown in FIG.
As shown in Fig. 1, by sandwiching the workpiece sphere 3 between two plate bodies 1 and 2 which are opposed to each other with a predetermined interval and serve as a grinding tool, and both plate bodies 1 and 2 are relatively rotated, The spherical body 3 to be machined rolls in a three-point contact state in an annular guide groove 4 having a V-shaped cross section provided on the disk body 1, and the surface thereof is ground into a spherical shape. . The cross-sectional shape of the guide groove 4 is continuous and uniform in the circumferential direction.

Further, as a mass-production type spherical grinding device, there is conventionally one shown in FIG. This is a grinding tool that stores a large amount of workpiece spheres 3 on the conveyor 5
The spheres 3 to be machined on the conveyor 5 are aligned and fed between the two boards 1 and 2 to be ground, and the sphere 3 to be machined makes one revolution between the boards 1 and 2 and then the sphere 3 is machined. The sphere 3 is returned to the conveyor 5 again and stored. By repeating this operation a number of times, the surface of the sphere 3 to be processed is ground into a spherical shape.

[0004]

In any of the conventional devices described above, when the sphere 3 to be machined makes one round between the boards 1 and 2 and returns to the original position, As a result of examining the grinding traces on the surface of the sphere 3 to be processed, most of them are only the grinding traces along substantially one direction as shown in FIGS. 14 (a) and 14 (b). It was found that the spheres 3 to be processed had little or no skew between them, or only a slight amount of skew was generated, and the grinding process was uneven.

Therefore, in order to uniformly grind the entire surface of the sphere 3 to be machined and improve its sphericity, the sphere 3 to be machined must pass between the disc bodies 1 and 2 many times. However, there is a problem in that the grinding processing efficiency becomes low.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a sphere grinding apparatus with improved sphericity and grinding processing efficiency.

[0007]

In order to achieve such an object, a sphere grinding apparatus of the present invention holds a sphere to be machined between two plate bodies facing each other with a predetermined distance therebetween, and In a sphere grinding device for grinding the surface of the sphere to be processed into a true sphere by rotating at least one of the two spheres, the sphere to be processed is circumferentially transferred to at least one of the two spheres. An annular guide groove for dynamic guidance is provided, and the cross-sectional shape of the guide groove is such that the contact point between the guide groove and the work sphere is periodic when the work sphere revolves around the guide groove on its circumference. It is characterized in that it is continuously changed in the circumferential direction of the board so as to change.

[0008]

Since the cross-sectional shape of the guide groove continuously changes in the circumferential direction, the position of the contact point between the sphere to be machined and the two plates changes from moment to moment, and the contact point changes accordingly. Since the peripheral speed of the board at and the peripheral speed at the contact point of the sphere to be machined are different from each other, the rotation axis of the sphere to be machined, which is determined by the frictional force and the peripheral speed of a plurality of contact points, changes momentarily. A sufficient skew is generated in the sphere to be processed between the two disc bodies. As a result, the entire surface of the sphere to be processed comes into contact with the disk body, which is a grinding tool, in an extremely short time, and is uniformly ground, so that the sphericity is improved. Further, since the rotation axis of the sphere to be machined largely changes as described above, the amount of relative slippage at the contact point between the sphere to be machined and the disk body increases, so that the grinding efficiency is improved.

[0009]

Embodiments of the present invention will be described below with reference to FIGS.

[First Embodiment] FIG. 1 is an explanatory view of a contact state between a workpiece sphere and two plates in a sphere grinding apparatus according to the first embodiment of the present invention. Are plate bodies facing each other at a predetermined interval, and one (upper in the figure) board (grinding stone board) 10 is fixed, and the other (lower in the figure) board (supporting board) 11 is the center. It is rotatable about an axis (not shown).

One side surface of the other board 11 (one board 10
An annular guide groove 12 is provided on the surface (opposing surface).
The guide groove 12 guides the sphere 13 to be machined, which is clamped in a state where a constant pressure is applied between the two disc bodies 10 and 11, in a circumferential direction. The cross-sectional shape of the guide groove 12 is a V-shape having an internal angle (opening angle) θ of 90 ° (it can be any number within the range of 50 ° to 120 °), and the processed spherical body 13
The revolution PCD is not changed, and the distance from the center of the sphere 13 to be processed to one board 10 and the distance to the rotation center axis of the other board 11 are constant over the entire circumference.

As shown in FIG. 2, the cross-sectional shape of the guide groove 12 is such that the sphere 13 to be machined is clamped between the two disc bodies 10 and 11 and rolls, so that a correct circular motion (processed when the circular motion is made) is performed. The locus of the center of the sphere 13 is shown by the alternate long and short dash line L in FIG. 2) and is guided to the circular donut virtual body 14 constituted by the envelope of the sphere 13 to be processed in the circumferential direction. The left and right inclined surfaces 12a and 12b of the groove 12 are in contact with each other, and the intersection point X of the left and right inclined surfaces 12a and 12b continuously changes by drawing a sine curve (sine curve) L ₁ with respect to a correct circle in the circumferential direction. To do.

That is, first, as shown in (a) of FIG. 1, the workable spherical body 13 which is sandwiched between the two disc bodies 10 and 11 and ground and processed is the contact point with the other disc body 11. B, C
From the contact points B and C and the rotation center O of the other plate 11 to the rotational speed of the peripheral speed proportional to the distances RB and RC, centering on the rotation axis O'-O '. Both boards 10,1
For contact points A, B, C with 1, contact points A, B, C
Between the rotation axis and the rotation axis O'-O 'ra, rb, rc
Rotates at a peripheral speed proportional to. In addition, each contact point A, B, C
Depending on the frictional force and the peripheral speed, the sphere 13 to be processed rotates while generating a slight relative slip between the spheres 10 and 11.

In the conventional apparatus described above, in this state, the sphere 13 to be machined returns to its original position after making one revolution with respect to the one plate that does not rotate. At that time, the sphere 1 to be machined
The traces of the grinding process added to the surface of No. 3 are shown in FIG.
As shown in (b), the traces of the unidirectional grinding process have almost no skew.

On the other hand, in the present invention, as shown in FIG. 1 (a), the left and right inclined surfaces 12 of the guide groove 12 which come into contact with each other at the contact points B and C between the sphere 13 to be machined and the other board 11.
The intersection X of a and 12b is the other board 11 as shown in FIG.
Draw a sine curve L ₁ with respect to a correct circle in the circumferential direction of the board 11 and continuously change in the circumferential direction of the board 11, and at a certain position on the circumference, as shown in (b) of FIG. The intersection of the left and right inclined surfaces 12a and 12b of the groove 12 is X (b), and the contact point between the workpiece sphere 13 and the left and right inclined surfaces 12a and 12b is B.
(B) and C (b), and the axis of rotation of the spherical body 13 to be processed becomes O'-O '(b).

Therefore, the sphere 13 to be processed is shown in FIG.
From the state of FIG. 1, the rotation axis O′-O ′ shown in (b) of FIG.
One plate body 1 which is a grinding tool rolling around (b)
0 is the contact point A (b), and the other board 11 is the contact point B
(B) and C (b) are brought into contact with each other, and the surface thereof is ground into a spherical shape.

The left and right inclined surfaces 12a of the guide groove 12 are
The intersection of 12b draws a sine curve for the correct circle, and at a certain position on the circumference, as shown in (c) of Fig. 1, X (c)
Therefore, the rotation axis of the workpiece sphere 13 is O′−
It becomes O '(c), and both discs 10 and 11 and the processed sphere 13
The contact points with are A (C), B (C), C (C),
In this state, the surface of the sphere to be processed 13 is ground into a spherical shape.

Therefore, the sphere 1 to be processed is assumed to be ground at the three positions of (a), (b) and (c) in FIG.
It is found that the trace of the grinding process on the surface of No. 3 is estimated as shown in FIG.

However, in reality, the intersection X of the left and right inclined surfaces 12a and 12b of the guide groove 12 is repeated a plurality of times within one circumference with respect to the correct circle to draw a sinusoidal curve and set the phase at the original position. Since it is designed to return together, while the sphere 13 to be processed makes one revolution between the two disc bodies 10 and 11,
Since a large number of skews are continuously repeated, the entire surface of the sphere to be processed 13 is uniformly ground and ground.

FIG. 3B is a view showing a trace of the grinding process added to the surface of the sphere 13 to be machined while the sphere 13 actually makes one revolution between the disc bodies 10 and 11. As is clear from the above, it is found that the entire surface of the spherical body 13 to be machined is evenly ground into a true spherical shape only by making one round between the two disc bodies 10 and 11.

FIG. 4 is a comparison diagram showing the relationship between the sphericity of the surface of the sphere to be machined and the grinding time between the grinding process by the device of the present invention and the grinding process by the conventional device. A) shows the case of the device of the present invention, and (B) shows the case of the conventional device. As is clear from the figure, the apparatus of the present invention significantly shortens the processing time for obtaining the same sphericity, and the final arrival accuracy is considerably improved, as compared with the conventional apparatus.

Next, the guide groove 12 having a V-shaped cross section as described above.
5 to 7 about the method of attaching the other board 11 to the other board 11.
It will be explained based on.

FIG. 5 is a perspective view of a cutting device for attaching a guide groove 12 having a V-shaped cross section to the other board 11 by cutting, and FIG. 6 is a block diagram of the cutting device. In the figure, 15 is a rotary main shaft to which the other board 11 is attached, and is driven by a drive motor 16. The drive motor 16 is controlled by a rotation speed control / phase control command from the control unit 23 and a feedback signal from the rotary encoder 17.

On the other hand, a cutting tool 18 for cutting the guide groove 12 on the other board 11 is attached to the swing shaft 19. This swing shaft 19 is connected to a cutting tool oscillation drive motor 21 via a crank mechanism 20,
It is driven by the drive motor 21. The cutting tool oscillation drive motor 21 uses the second rotary encoder 2 and the rotation speed control / phase control command from the control unit 23.
2 and the feedback signal from 2.

The cutting tool 18 has a V-shaped cross section which is in contact with the circular donut virtual body 14 formed by the sphere 13 to be machined having the preset dimensions shown in FIG. 2 which is supposed on the board surface of the other board 11. The guide groove 12 of is cut. Therefore, as shown in FIG. 7, due to the swinging of the cutting tool 18 within the swinging angle θ ₁ , (1) the state of the solid line → (2) the state of the broken line → (3) the state of the solid line → (4) 2 points State of chain line → (5)
The axis passing through the center O of the circular donut virtual body 14, that is, the circle 23 having a preset size in FIG. ₂
To match.

Therefore, the cutting tool 18 is swung to make a cross-section V.
Even if the V-shaped guide groove 12 is cut, the workable spherical body 13 having a predetermined size that rolls in the guide groove 12 is correct with respect to the center of the circumferential groove of the other board 11. It is capable of performing a circular motion.

By the way, in the cutting of the guide groove 12 having a V-shaped cross section, if the rotation of the rotary main shaft 15 and the cutting tool oscillation drive motor 21 are made constant, the inclined surfaces 12a and 12b of the guide groove 12 described above are formed. The locus of the intersection X, that is, the tip of the V-shaped cutting tool 18 is a sine curve, but is not limited to the sine curve. Further, the guide groove 12 having a V-shaped cross section needs to be aligned in the original phase when the other board 11 is rotated once in order to prevent scratches due to a sharp skew on the circumference. Therefore, the other board 1
The rotation speed and phase of both drive motors 16 and 21 are controlled so that the ratio of the total circumferential length of the first guide groove 12 to the cycle of the sine curve is a positive multiple.

The cyclic change of the width of the guide groove 12 in the circumferential direction and the contact points B and C of the sphere 13 to be processed in the guide groove 12 change in opposite phases, and the revolution PCD of the sphere 13 to be processed is cyclic. It does not change and is a perfect circle.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same parts as those in the first embodiment described above will be described with the same reference numerals in the drawings.

In the present embodiment, the cross-sectional shape is a partial arc-shaped portion 12'a on the surface of the other board 11 facing one board 10.
An annular guide groove 12 'having a U-shaped portion 12'b is provided on the bottom of the plate, and an annular shape whose cross-sectional shape is a partial arc on the surface of one plate body 10 facing the other plate body 11. The guide groove 24 is provided. The radius of the partial arc-shaped portion of the cross section of the guide groove 24 of one board 10 and the partial arc-shaped portion 1 of the cross section of the guide groove 12 'of the other board 11.
The radius of 2'a is set to approximately 1/2 of the diameter of the sphere 13 to be processed. The U-shaped portion 12'b of the guide groove 12 'of the other board 11 continuously changes in position in the left-right direction in a sinusoidal shape with respect to the correct circle in the circumferential direction of the other board 11. That is, FIGS. 8B and 8C show the position change of the U-shaped portion 12'b.

In FIG. 8A, the center of the position where the sphere 13 to be processed comes into contact with one board 10 is A, and the other board 11 is the center.
The centers of the positions that come into contact with B and C are B and C, respectively, so that the axis of rotation of the spherical body 13 to be machined is O'-O 'as in the first embodiment.

On the other hand, in FIG. 8B, the axis of rotation of the sphere 13 to be machined is O'-O '(B), and in FIG. 8C, the axis of rotation is O'-O' (C). The workpiece sphere 13 continuously changes its rotation axis between the two disc bodies 10 and 11 to generate a skew, and the entire surface of the workpiece sphere 13 is ground into a true spherical shape in a short time. .

Therefore, 3 in FIGS. 8A, 8B, and 8C.
The sphere 13 to be processed is assumed to be ground at a position.
9 (a) is estimated when the grinding trace of the surface of No. 1 is shown, but the grinding trace of the surface of the sphere 13 to be processed, which has been actually ground once between the two disc bodies 10 and 11, is shown. Figure 9
It becomes like (b).

Next, a method of attaching the guide groove 12 'to the other board 11 will be described with reference to FIG. First, the cutting tool 18'a of FIG. 11A is attached to the swing shaft 19 'which is linearly swung by the cutting tool oscillation drive motor 21, and the swing shaft 19' is guided without swinging. Groove 1
The 2'partially arcuate portion 12'a is cut (the guide groove 24 'can be attached to the other board 10 in the same manner). Next, the cutting tool 18 'of FIG. 11B is replaced with the swing shaft 19', and the swing shaft 19 'is swung to cut the U-shaped portion 12'b of the guide groove 12'. To do.

The rotation speed / phase control of the rotary main shaft 15 and the swing shaft 19 'is the same as in the first embodiment.

A guide groove 12 'for the other board 11
The U-shaped portion 12'b can be cut by an eccentric cutting method. Further, the installation of the partial arc-shaped portion 12'a of the guide groove 12 'on the other board 11 and the installation of the guide groove 24 on the other board 10 are performed in advance by acclimatization forming processing by the sphere 13 to be processed. There is also a method.

The cross-sectional shape of the guide groove attached to the other board in the present invention is not limited to the above-mentioned embodiments.
Various shapes such as arcuate shape, U-shape, trapezoidal shape, etc. can be selected.

Further, with respect to both boards, either one or both may be rotated. Further, the mode in which the cross-sectional shape of the guide groove continuously changes in the circumferential direction of the board is not limited to the one that changes in a sinusoidal curve, and can be changed cyclically in the revolution PCD of the sphere to be processed. Anything that changes by drawing a closed loop that returns to the original position may be used.

The requirements for the guide groove of the present invention are as follows.

First, when viewed from the periodic swinging of the contact point between the sphere to be processed and the board, the sphere of the sphere to be processed passes through the rotation center of the sphere to be processed, and is seen from the center of rotation. The swing axis that is 1/2 of the included angle of the line connecting the two contact points of the sphere to be contacted with the rotation center and the guide groove changes continuously and cyclically on the revolution PCD of the sphere to be machined. Must be a guide groove.

When one of the plates 10 is a flat surface, the revolution P is seen when seen from the periodic swing of the sphere to be processed.
The rotation center of the sphere to be revolved on the CD is the revolution PC
It may be a guide groove that changes periodically around D.

Further, in view of the continuity of the changing cycle, when the sphere to be processed revolves once on the revolving PCD, it is a guide groove in which the cycle is an integer cycle.

[0043]

As described above, according to the sphere grinding apparatus of the present invention, the entire surface of the sphere to be processed comes into contact with the plate body, which is a grinding tool, in an extremely short time, and is uniformly ground. The sphericity is improved. Further, since the rotation axis of the sphere to be machined largely changes, the amount of relative slippage at the contact point between the sphere to be machined and the disc body increases, so that grinding efficiency is improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a contact state between a workpiece spherical body and two plate bodies of a spherical body grinding apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a changed state of a cross-sectional shape of a guide groove in the same device.

FIG. 3 is a diagram showing a grinding trace of the surface of a sphere to be processed that has been ground in the same apparatus.

FIG. 4 is a comparison diagram showing a relationship between processing time and sphericity in the device of the present invention and the conventional device.

FIG. 5 is a perspective view of a cutting device for providing a guide groove to the other board in the device of the present invention.

FIG. 6 is a block configuration diagram of the cutting device.

FIG. 7 is a diagram showing a swinging state of a cutting tool in the cutting device.

FIG. 8 is an explanatory diagram of a contact state between a workpiece spherical body and two plate bodies of a spherical body grinding apparatus according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a grinding trace on the surface of a sphere to be ground that has been ground in the same apparatus.

FIG. 10 is a perspective view of a cutting device for providing a guide groove on the other board of the device.

FIG. 11 is a partially cutaway plan view of a cutting tool used in the cutting device.

FIG. 12 is a cross-sectional view of a conventional spherical grinding device.

FIG. 13 is a perspective view of a conventional spherical grinding device different from that of FIG.

FIG. 14 is a diagram showing a grinding trace of the surface of a sphere to be processed that has been ground by a conventional device.

[Explanation of symbols]

 10 One board 11 The other board 12, 12 'Guide groove 13 Worked sphere

Claims (1)

[Claims] 1. A surface of the sphere to be machined is held by sandwiching the sphere to be machined between two spheres facing each other with a predetermined distance therebetween and rotating at least one of the two spheres. In a spherical grinding device for grinding into a spherical shape, an annular guide groove for rollingly guiding the processed spherical body in a circumferential direction is provided on at least one of the two plate bodies, and the cross-sectional shape of the guide groove is When the sphere to be machined revolves around the guide groove on its circumference, the contact point between the guide groove and the sphere to be machined is changed continuously in the circumferential direction of the board so as to change periodically. Sphere grinding machine characterized by.