JP2638926B2 - Spherical grinding machine and shape accuracy maintenance method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spherical grinding apparatus used for spherical grinding of hard and brittle materials such as optical glass lenses, and a method for maintaining shape accuracy in continuous processing. .

2. Description of the Related Art In a conventional spherical grinding apparatus for optical glass lenses (see, for example, JP-A-58-151236), as shown in FIG.
The lens 3, which is attached to the rotary spindle 2 and is rotated at a low speed, is tilted at a predetermined tilt angle by the tilt rotation shaft 4, and further mounted on the high-speed rotary spindle 6, which is placed at a predetermined position by the parallel slide shaft 5, and is rotated at a high speed. The rotating diamond grindstone 7 is fed by a drive motor 8 and is ground into a spherical surface having a predetermined radius of curvature.

The method of maintaining shape accuracy during continuous processing using the spherical grinding device for a lens configured as described above, first,
Before starting the continuous machining, the trial machining is performed by the above-described operation, and the inclination angle of the inclined turning shaft 4 is corrected and the index position of the parallel slide shaft 5 is corrected so that the curvature shape of the workpiece has a predetermined accuracy. Further, the feed amount of the lens to the grindstone 7 by the drive motor 8 is corrected so that the center thickness of the workpiece becomes a predetermined size.

Next, continuous machining is started. However, the tip of the grindstone 7 wears little by little each time it is used for grinding, so that a curvature shape error and a center thickness error of the processed lens occur. Therefore, the accuracy of the shape of the processed lens is periodically measured, and the above-mentioned respective axes are corrected when the quality exceeds the quality control range.

SUMMARY OF THE INVENTION However, in the conventional spherical grinding apparatus and the method of maintaining the shape accuracy having the above-described configuration and operation, as shown in FIG. In addition, the correction of the center thickness error requires correction operation of a total of three axes, such as correction of the tilting rotation axis a, correction of the parallel slide axis b, correction of the feed amount of the workpiece to the grinding wheel c, and so on. The shape quality at the time of processing is as shown in FIG.

Further, as shown in FIG. 5, as described above, the number of correction axes for securing the shape accuracy is as many as three, and in addition to the heat generated by the heat generated by the bearings and the drive motor of the high-speed rotary drive grindstone rotary spindle. In some cases, the position of the tip of the grindstone changes due to deformation, and the correction of the shape error of the workpiece does not go as intended.

Therefore, there is a problem that a great deal of labor is required to secure the shape accuracy of the workpiece, that is, the curvature shape accuracy and the center wall thickness accuracy, and to maintain them.

SUMMARY OF THE INVENTION The present invention provides a spherical grinding apparatus and a method for maintaining the shape accuracy, which can extremely easily secure the shape accuracy of a workpiece at a high level and can easily maintain the shape accuracy during continuous machining. is there.

Means for Solving the Problems To solve the above problems, the spherical grinding apparatus of the present invention comprises a cup-shaped grinding wheel, a grinding wheel rotating spindle for rotating the grinding wheel at a high speed, and a predetermined curvature shape of the rotating grinding wheel. A turning mechanism that tilts and arranges the workpiece at a predetermined angle so as to be processed, a slide mechanism that shifts and arranges the grinding wheel so that the grinding wheel contacts the rotation center of the workpiece, and a rotation mechanism of the workpiece that opposes the grinding wheel arranged in this way. The grinding wheel rotary spindle is provided with a slide mechanism capable of processing operation in the direction of the rotation axis, and further supplies a temperature-controlled grinding fluid directly to the grinding portion, and further, through the center of the rotation shaft of the grinding wheel rotary spindle. It is supplied to the grinding work through the hole and further supplied to the inside of the grindstone rotary spindle main body to cool the bearing and the drive motor.

Further, the shape accuracy maintaining method of the present invention is characterized in that the NC automatic correction of the axial operation position of the grindstone rotating spindle is performed for each workpiece or every several pieces according to the wear speed of the cup-shaped grindstone tip in the rotational axis direction. By maintaining the absolute position of the tip,
This maintains the shape accuracy of the workpiece, that is, the curvature shape accuracy and the center thickness accuracy.

Operation The present invention makes it possible to arbitrarily change the axial operation position of the grindstone rotating shaft at the tip of the grindstone acting on the workpiece of the cup-shaped grindstone by NC data and to reduce the thermal deformation of the main mechanism by the above configuration. Thus, the above operation accuracy is stabilized.

Further, according to the present invention, according to the above-mentioned method, either the curvature shape error of the processed workpiece during the continuous processing or the data of the center thickness error and the number of processed workpieces, and the whetstone tip The wear rate in the direction of the rotation axis of the part is calculated,
The absolute position of the tip of the grinding wheel is maintained by performing NC automatic correction of the operating position in the axial direction of the grinding wheel rotary spindle for each workpiece or every several pieces, thereby maintaining the curvature shape of the workpiece. Accuracy and center thickness accuracy are automatically maintained.

Embodiment Hereinafter, a spherical grinding apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

First, FIG. 1 is a perspective view of an optical glass lens spherical grinding device, and FIG. 2 is a cross-sectional view of an upper portion of the optical glass lens spherical grinding device. 9 is a cup-shaped diamond whetstone, 10 is this diamond whetstone attached and this is 20,0
A grindstone rotating spindle that rotates at a high speed of 00 rpm to 40,000 rpm. Reference numeral 11 denotes a slide base, which has a turning mechanism in the a-direction about a shaft 12 as a center of rotation. The slide base 11 is disposed at a predetermined angle via a gear 14 using a handle 13. A slide mechanism in the direction b is provided between the slide base 11 and the slider 15, and the handle 16
Turn the ball screw 17 to displace it horizontally. The lens 18 to be processed is clamped and rotated by a collet chuck 21 attached to a rotating mechanism composed of a rotating spindle 19 and a driving motor 20. The above-mentioned whetstone rotating spindle 10
Is fixed to a spindle holder 22, which is incorporated in a slider 23. The grindstone rotating spindle 10 performs an indexing operation in the grindstone rotating shaft direction, that is, the d direction via a nut 26 by a ball screw 25 driven by a drive motor 24.

The operation of the drive motor 24 is controlled by an NC device (not shown), and controls the feed speed and position of the grindstone rotating spindle 10 in the d direction.

A built-in type high frequency motor, that is, a stator 27 and a rotor 28 are incorporated in the grindstone rotating spindle 10 to rotate a cup-shaped diamond grindstone attached to a rotating shaft at high speed. In order to suppress the heat generated by the stator at this time, a grinding liquid or city water whose temperature is controlled is circulated to the cooling jacket portion 29. The grindstone rotating spindle 10 has a through hole at the center of the rotating shaft, and supplies a temperature-controlled grinding fluid to the grinding section through this hole.

The operation of the optical glass lens spherical grinding apparatus having such a configuration will be described below.

First, the lens 18 to be processed is clamped by the collet chuck 21, and the rotating spindle is driven by the drive motor 20 to rotate at low speed. The grinding wheel rotating spindle 10 is tilted by rotating the slide base in the direction a so that the cup-shaped diamond grinding stone 9 processes the lens 18 to be processed into a predetermined curvature shape. Further, when the grinding wheel rotating spindle is fed to a predetermined position, the slider 15 is slid in the direction b so that the tip of the diamond grinding stone is in contact with the rotation center of the lens 18 to be processed, and the grinding wheel rotating spindle 10 is shifted laterally. As described above, the diamond grindstone 9 mounted on the grindstone rotating spindle arranged at a predetermined position and rotating at a high speed is fed to the lens 18 rotating at a low speed by the drive motor 24 for processing.

The operation of the drive motor 24 is controlled by an NC device (not shown), and the diamond grindstone 9 cuts into the lens 18 to be processed at a predetermined feed speed to a predetermined cutting position. Then, when cutting is performed to a predetermined cutting position, the position is maintained for a certain period of time to finish the shape of the lens to be processed 18 in a rotationally symmetric manner. Thereafter, the grindstone is separated from the lens to complete the processing.

Cooling jacket during rotation of grindstone rotating spindle 10
The grinding fluid is circulated to 29, and the grinding fluid is supplied from the spindle rotation center hole during lens processing.

As described above, according to this embodiment, the curvature shape and the center thickness of the lens can be simultaneously finished by cutting the diamond grindstone by controlling the operation from the direction of the grindstone rotating spindle rotation axis. Further, the error of the shape due to the wear of the grinding wheel can be corrected only by correcting the NC data in the direction of the rotating shaft of the grinding wheel.

 Next, the shape accuracy maintaining method of the present invention will be described.

First, the curvature depth error of the processed lens is measured.
The correction amount of the indexing position at which the cutting operation of the diamond grindstone 9 is stopped is calculated from the curvature depth error. The correction amount is added to the NC data at the d-direction feed stop position of the NC device (not shown) to correct the curvature shape of the lens. At this time, since the curvature depth error and the center thickness error of the lens to be processed due to the wear of the diamond grindstone 9 are proportional, the correction corrects the center thickness error of the lens.

In addition, the wear speed in the rotation axis direction of the diamond grindstone is calculated from the relationship between the number of continuous machining and the curvature depth error, and the grindstone wear amount per machining is obtained from this. This grindstone wear amount is added to the feed stop position in the d direction of the NC data for each processing.

As described above, according to the method of the present invention, the feeding absolute position of the tip portion of the diamond grindstone is maintained, the curvature depth and the shape quality of the center wall thickness are extremely stable as shown in FIG. Decrease. Further, since the correction is performed only for one axis in the d direction, the correction time required for one correction is greatly reduced. For the reasons described above, it is possible to reduce the loss time due to the correction at the time of continuous processing production.

Effects of the Invention As described above, the first invention of the present invention provides a cup-shaped grindstone, a grindstone rotating spindle for rotating the grindstone at high speed,
A turning mechanism that inclines and arranges the rotating whetstone at a predetermined angle so that a predetermined curvature shape is processed, a slide mechanism that displaces the whetstone sideways so that the whetstone is in contact with the rotation center of the workpiece, and a whetstone arranged in this manner. By providing a spherical grinding machine having a rotating mechanism for an opposed workpiece and a sliding mechanism capable of indexing the grinding wheel rotary spindle in the direction of the rotation axis, the grinding wheel is fed by the indexable slide mechanism to perform machining. This is to correct the shape error due to the wear of the grindstone with only the slide shaft.

The second invention of the present invention achieves the above effects by providing a spherical grinding apparatus provided with a slide mechanism for NC-operating the grindstone rotating spindle in the rotation axis direction in the above-described processing method.

According to a third aspect of the present invention, a grinding fluid whose temperature is controlled in the above-described processing method is directly supplied to a grinding section,
By supplying the grinding wheel through the center through hole of the rotating shaft of the grindstone rotating spindle to the grinding portion and further to the inside of the grindstone rotating spindle main body, the bearing portion of the spindle and the drive motor are cooled.

According to a fourth aspect of the present invention, the index position in the axial direction of the grindstone rotating spindle is corrected for each workpiece or every several pieces in accordance with the wear speed of the tip of the cup-shaped grindstone in the rotational axis direction, and By maintaining the absolute position, the machining shape accuracy is maintained, the number of corrections and the correction time are reduced, and the loss time due to the correction during continuous processing is greatly reduced, and the depth of curvature of the processed workpiece is realized. By calculating the axial index position correction amount of the grindstone rotating spindle from the error and performing the correction, the curvature depth error and the center thickness error of the workpiece are simultaneously corrected to obtain the above-described effect.

According to a fifth aspect of the present invention, an axial position correction amount of a grindstone rotating spindle is calculated and corrected from a center thickness error of a workpiece processed by the above method,
The above effect is obtained by simultaneously correcting the curvature depth error and the center thickness error of the workpiece.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a workpiece machined by the above-described method, in which a curvature depth error or a center thickness error, and the number of workpieces machined so far, the wear of the tip portion of the grinding wheel in the rotation axis direction. The above effect is obtained by calculating the speed and correcting the indexing position in the axial direction of the grindstone rotating spindle according to the speed.

[Brief description of the drawings]

FIG. 1 is a perspective view of a spherical grinding apparatus for an optical glass lens according to a first embodiment of the present invention, FIG. 2 is a top sectional view of the apparatus, FIG. 4th
FIG. 5 is a view showing the configuration of a conventional lens grinding apparatus, FIG. 5 is a view showing the shape quality during continuous processing by the conventional apparatus, and FIG. 6 is a view showing the correction direction in the conventional apparatus. 9 ... cup-shaped diamond whetstone (working tool), 10 ...
Grinding wheel rotary spindle, 18 ... lens to be processed (workpiece), 19 ... rotary spindle, 20 ... drive motor, 21
... Collet chuck, 24 ... Drive motor, 27 ... Stator, 28 ... Rotor, 29 ... Cooling jacket part.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoshi Mayahara 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Katsuyoshi Shingu 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-62-188664 (JP, A)

Claims (6)

(57) [Claims] 1. A cup-shaped grindstone, a grindstone rotating spindle for rotating the grindstone at a high speed, a turning mechanism for inclining the rotating grindstone at a predetermined angle so as to form a predetermined curvature shape, and a workpiece A slide mechanism for laterally displacing the grindstone so that the grindstone is in contact with the rotation center of the work piece, and a slide mechanism for rotating the workpiece opposed to the grindstone arranged in this way, and capable of indexing the grindstone rotating spindle in the rotational axis direction. A spherical grinding machine with a mechanism. 2. A spherical grinding apparatus according to claim 1, further comprising a slide mechanism for NC-operating the grinding wheel rotary spindle in the direction of the rotation axis. 3. A grinding liquid whose temperature is controlled is directly supplied to the grinding section, and is supplied to the grinding section through a central through hole of a rotating shaft of the grinding wheel rotating spindle, and further supplied to the inside of the grinding wheel rotating spindle body. The spherical grinding device according to claim 1, wherein the bearing and the drive motor are cooled. 4. The indexing position in the axial direction of the grinding wheel rotary spindle is corrected for each workpiece or every several pieces according to the wear speed of the tip of the cup-shaped grinding wheel in the rotation axis direction, and the absolute position of the grinding wheel tip is maintained. By maintaining the processing shape accuracy, the processed workpiece is calculated from the curvature depth error by calculating the indexing position correction amount in the bearing direction of the grindstone rotary spindle and performing the correction, thereby correcting the curvature depth error and the workpiece. Shape accuracy maintaining method for simultaneously correcting the center thickness error of 5. A curvature depth error and a center thickness error of a workpiece are simultaneously determined by calculating and correcting an axial position correction amount of a grinding wheel rotary spindle from a center thickness error of the processed workpiece. 5. The method according to claim 4, wherein the correction is performed. 6. A wear speed in a rotation axis direction of a tip portion of a grindstone is calculated from a curvature depth error or a center thickness error of a machined workpiece and the number of workpieces machined so far. The shape accuracy maintaining method according to claim 4, wherein the indexing position in the axial direction of the grindstone rotating spindle is corrected according to the following.