JPS6211986B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polishing apparatus for lapping, and more particularly to a polishing apparatus that can efficiently process the dimensions of a transparent workpiece with high precision.

Lapping is usually used to improve the roughness and shape accuracy of a machined surface. On the other hand, in lap machining, the amount of machining per unit time varies greatly depending on changes in machining conditions. Therefore,
When processing the workpiece with high precision (dimensions in the direction perpendicular to the processing surface), polishing and measuring the dimensions of the workpiece must be repeated many times from the start of processing until the required dimensions are achieved. is being carried out. For this reason,
The disadvantage is that productivity is drastically reduced.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a polishing device that detects the end position of the workpiece through the workpiece when processing a transparent workpiece, thereby improving productivity. be.

In order to achieve the above object, in the present invention,
Penetrates a workpiece held in a workpiece that rotates around an axis eccentric from the center of rotation of the lap surface plate, allowing the workpiece to slide freely through the workpiece and perpendicularly to the machined surface of the workpiece. A hole is formed,
Machining is carried out by placing a weight provided with an objective lens in this through hole so that the focal point is located a predetermined distance below the lower end surface of the through hole, and irradiating the machined surface of the workpiece through the objective lens. , detects the thickness of the workpiece by receiving the reflected light from the processing surface and converting it into an electrical signal, and comparing this signal with a preset reference value, and compares the signal and the reference value. The polishing apparatus is characterized in that the polishing device is stopped when the two match.

An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 show an embodiment of the present invention. In the figures, reference numeral 1 denotes a base, which rotatably supports a shaft 3 via a bearing 2, and is connected between a pulley 4 and the shaft 3. The power is transmitted by a gear device (not shown). 5 is a motor, and reducer 6
The pulley 7 and belt 8 of the reducer 6
Power is transmitted to the pulley 4 via the pulley 4 to rotate the shaft 3. 9 is a wrap surface plate,
It is fixed to the upper end of the shaft 3, and a polishing cloth 10 is fixed to the upper surface. Reference numeral 11 designates a support member, one end of which has a U-shaped opening is fixed to the bearing 2, and the other end projects above the polishing cloth 10. A support shaft 12 projects from one end of the support member 11 to face the polishing cloth 10, and a work holder 14 is rotatably coupled to the tip of the support shaft via a bearing 13. A through hole 15 is formed in the work holder 14, and a workpiece 16 and a weight 17 are slidably accommodated in the through hole 15. The weight 17 is attached to the main body 1 as shown in FIG.
A stepped through hole 19 is bored in the center of the hole 8 . The bearing 20 protruding into the through hole 19 includes
A feed screw 22 with a handle 21 fixed to one end is rotatably supported. Numeral 23 is a cylinder that holds the lens 24, and a nut 25 protruding from the outer surface of the cylinder is screwed into the feed screw 22.
The lens 24 is raised and lowered by the rotation of the lens 24. Reference numeral 26 is a half mirror, which is placed above a point on the locus that the center of the lens 24 passes when the lap surface plate 9 rotates, and the laser oscillator 2
A part of the laser beam from 7 is reflected to the lens 24.
The machined surface is irradiated through the machined surface, and a part of the reflected light from the machined surface is transmitted and received by the photo sensor 28. 29 is a control means, based on the electric signal from the photo sensor 28,
The power to the motor 5 is cut off, the motor 5 is stopped, and the machining is completed. As shown in FIG. 3, the control means 29 includes an amplifying circuit 31 connected to the photo sensor 28 and amplifying the signal applied from the photo sensor 28 to a size that allows signal processing; A bandpass filter 32 is connected and removes noise from the signal applied from the amplification circuit 31.
, an A/D conversion circuit 33 connected to this bandpass filter 32 and converting the signal applied from the bandpass filter 32 into a digital signal, and an A/D conversion circuit 33 connected to this A/D conversion circuit 33 and connected to two contacts A. , B, and the A/D conversion circuit 34 is connected to the contact A of the changeover switch 34.
a holding circuit 35 configured to hold the maximum value of the digital signal applied from the holding circuit 35 as a reference value; a latch clear switch 36 connected to the holding circuit 35 for erasing the value held by the holding circuit 35; 34 is connected to the holding circuit 35, the reference value applied from the holding circuit 35 and the digital signal applied from the A/D conversion circuit 33 are compared, and when the values match, one signal is oscillated. It is composed of a comparison circuit 37 and a switch circuit 38 connected to the comparison circuit 37, manually connected, and turned off by a signal applied from the comparison circuit 37. A monitor circuit 39 is connected between the changeover switch 34 and the holding circuit 35 to display the voltage applied from the A/D conversion circuit 33.

In the above configuration, in order to set the reference value in the holding circuit 35, the latch clear switch 36 is first set.
Press to erase the old reference value set in the holding circuit 35 and switch the changeover switch 34 to the contact A side. Meanwhile, the lapping agent is supplied onto the polishing cloth 10 while rotating the lapping surface plate 9, and after the lapping agent is dispersed on the polishing cloth 10, the lapping surface plate 9 is stopped and the work holder 1 is
A master gauge machined to predetermined dimensions and a weight 17 are inserted into the through hole 15 of No. 4. Then, a laser beam is oscillated from the laser oscillator 27, and the contact surface between the master gauge and the polishing cloth 10 is irradiated through the half mirror 26 and the lens 24, and the reflected light is
The light is received by a photo sensor 28 via a lens 24 and a half mirror 26. In this state, handle 2
1 to adjust the focus of the laser beam focused by the lens 24 to the master gauge and polishing cloth 1.
Align with the contact surface of 0. This is the monitor circuit 39
This is achieved by positioning the lens 24 so that the output of the A/D conversion circuit 33 is maximized while watching the display. After setting the reference value in this way, the changeover switch 34 is switched to the contact B side. On the other hand, after removing the weight 17 and the master gauge and setting the workpiece 16 in the through hole 15, the weight 17 is placed on it. In this state, while supplying the lapping agent onto the polishing cloth 10, the motor 5 is operated to rotate the lapping surface plate 9. Then, the workpiece 16 is polished. At this time, since the work holder 14 is in an eccentric position with respect to the polishing cloth 10, the work holder 14 also
It rotates around the support shaft 12. Therefore,
Once every time the work holder 14 rotates once,
The workpiece 16 passes under the half mirror 26. When the workpiece 16 is located under the half mirror 26, it is irradiated with laser light, and the reflected light is received by the photo sensor 28 and converted into an electrical signal. The output of the photo sensor 28 is sent to the amplification circuit 3.
1. Bandpass filter 32, A/D conversion circuit 3
3 and a changeover switch 34 to a comparison circuit 37, where it is compared with a reference value set in a holding circuit 35. At this time, when the output of the A/D conversion circuit 33 and the reference value match, a signal is oscillated from the comparison circuit 37, and the switch circuit 38 is activated to stop the motor 5. In this way, the workpiece 10 is processed to a predetermined size.

Note that when setting the reference value, if a master gauge is not used, the lens 24 is adjusted so that the focal point is located below the lower end surface of the weight 17 by a predetermined dimension (dimension of the workpiece 16 after processing). , place it on the workpiece 10 or a dummy made of the same material, polish it until the output of the A/D conversion circuit 33 exceeds the maximum value, and set the maximum value as the reference value. do it.

As described above, according to the present invention, the processing position of the transparent workpiece is irradiated during the polishing process, and the amount of processing of the workpiece is detected by receiving the reflected light. Machining can be carried out continuously from start to finish without stopping the machine, greatly improving productivity. Furthermore, since the amount of processing is detected under the same conditions, it is possible to improve the quality of the processed workpiece after processing and obtain products with less variation.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of a polishing apparatus according to the present invention, FIG. 2 is an enlarged sectional view of a weight in FIG. 1,
FIG. 3 is a block diagram of the control means in FIG. 1. 9: Lap surface plate, 12: Support shaft, 14: Work holder, 15: Through hole, 16: Workpiece, 17:
Weight, 18: Main body, 19: Through hole, 24: Lens,
26: Half mirror, 27: Laser oscillator, 28:
Photo sensor, 29: control means.

Claims (1)

[Claims] 1. A polishing device that polishes a transparent workpiece held by a workholder that rotates around an axis eccentric from the center of rotation of a lap surface plate, with a weight slidably passing through the workholder. A through hole is formed perpendicular to the processing surface of the workpiece, and a weight is provided with an objective lens such that the focal point is positioned downward by a predetermined dimension from the lower end, and a weight is provided in the through hole. An optical means comprising a light source that illuminates the processing surface of the workpiece, a light receiving element that receives reflected light from the processing surface and converts it into an electrical signal, and a signal output from the light receiving element that is set in advance. 1. A polishing device comprising a control means for comparing the signal with a reference value and stopping the polishing device when the signal and the reference value match.