JP2000079546A - Optical element member centering and edging grinding wheel and centering and edging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a loss at rise up time when a new grinding wheel is used, in centering and edging work of a lens. SOLUTION: A grinding wheel 10 has a centering and edging part 12a and chamfering parts 12b, 12c grinding the outer peripheral part of a lens, and these parts are constituted by an abrasive grain layer 14 electro-deposited in an abrasive grain fixed surface 13 of a grinding wheel main unit 11. A radial reference surface 15a and a thrust reference surface 15b are formed in a work process working the abrasive grain fixed surface 13 to the grinding wheel main unit 11, the grinding wheel 10 is rotated by mounting it in a spindle of a centering and edging machine, rotational deflection in a radial/thrust direction is measured by using the reference surfaces 15a, 15b, and a mounting part or the like of the grinding wheel 10 relating to the spindle is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element member centering grindstone and a centering method used for centering by grinding an outer peripheral portion of an optical element member such as various lenses.

[0002]

2. Description of the Related Art Centering of an optical element member such as a lens is performed by rotating the optical element member around its optical axis and grinding the outer peripheral portion with a rotary grindstone.

FIG. 12 shows a conventional centering whetstone used for centering a lens. The whetstone 100 includes an annular centering portion 112a formed at the center of the cylindrical surface of a whetstone main body 111, It has a pair of inclined chamfers 112b and 112c protruding on both sides thereof. In the lens centering process, first, the grindstone 100 is moved perpendicularly to the rotation axis of a rotating lens (not shown). (Cut feed),
The centering portion 112a contacts the outer peripheral edge of the lens. Thereby, the outer peripheral edge of the lens is ground so as to be a perfect circle centered on the optical axis.

Subsequently, the grindstone 100 is moved parallel to the optical axis of the lens (transverse feed), and chamfering is performed with one chamfered portion 112b abutting on one side of the lens. Further, if necessary, the grindstone 100 is moved in the direction of the optical axis of the lens in a direction opposite to the above, and the other chamfered portion 112c is chamfered in contact with the opposite side surface of the lens.

The centering of the lens generally includes centering by grinding the outer peripheral edge of the lens and chamfering the side edge of the outer peripheral portion.

[0006] The lens centering required for a high-precision lens system requires polishing the surface of the outer peripheral portion of the lens to 3 to 4 µm (Rmax) in addition to extremely high accuracy of the outer shape of the lens. This is to prevent ghost and flare caused by internal reflection (see the optical element processing technology “92” issued by the Japan Opto-Mechatronics Association).

[0007]

However, according to the above prior art, in the centering process of a lens or the like, in the centering process immediately after replacing a whetstone whose service life has expired with a new whetstone, generally a whetstone is used. Has a roughness of 5 μm (Rm
ax) or more, and damage due to chipping or the like of the processed surface occurs. Therefore, the processing time is required to obtain the surface accuracy required for the polished lens, ie, the roughness of the lens polished surface of 3 to 4 μm (Rmax). There is an unsolved problem that the length must be lengthened and so-called startup loss is large.

The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and reduces a loss at the time of starting when using a new grindstone, thereby greatly improving processing accuracy and processing efficiency. It is an object of the present invention to provide an optical element member centering grindstone and a centering method that can be performed.

[0009]

SUMMARY OF THE INVENTION To achieve the above object, an optical element member centering whetstone of the present invention is a rotary whetstone used in an optical element member centering step, and has a rotational deflection in a predetermined direction. A grinding wheel main body having a reference surface for measuring the particle size and an abrasive grain layer supporting surface, and an abrasive layer attached to the abrasive grain layer supporting surface of the grinding stone main body.

It is preferable that the grindstone main body has a first reference plane for measuring a rotational runout in a radial direction and a second reference plane for measuring a rotational runout in a thrust direction.

[0011] It is preferable that the reference surface of the grindstone main body and the abrasive grain layer supporting surface are formed by the same processing step.

[0012] It is preferable that the grindstone main body is provided with balance correcting means for reducing imbalance during rotation.

It is preferable that the unbalance amount during rotation is corrected by the balance correcting means to be 5 gf or less.

[0014] It is preferable that the apparatus is attached to the centering machine so that the rotational runout in a predetermined direction is 10 µm or less.

[0015] It is preferable to mount the apparatus on the centering machine such that the rotational runout in the radial and thrust directions is 10 µm or less.

According to the centering method of the present invention, the optical element member centering grindstone is mounted on a centering machine and rotated to measure rotational vibration using a reference surface, and the measured rotational vibration is reduced. The method is characterized in that it has a step of adjusting the whetstone mounting portion of the centering machine as described above.

[0017] It is preferable that the method further includes a step of adjusting the processing device for the grindstone main body of the new grindstone based on the measured rotational runout.

A step of dressing the abrasive layer to a predetermined surface roughness may be added.

[0019]

[Function] When processing the main body of a rotary grindstone to be mounted on a centering machine for an optical element member such as a lens, a reference surface for measuring rotational runout is processed in the same processing step as the abrasive layer support surface. deep. After correcting the static imbalance and dynamic imbalance of the rotating grindstone to, for example, 5 gf or less, the grindstone is mounted on a spindle or the like of a centering machine and rotated (test rotation), and rotated using the reference surface. Measure run-out. Based on the measured rotational runout, the bearing of the spindle of the centering machine is corrected, and the rotational runout of the grindstone is reduced by, for example, 10 μm.
m or less.

In this manner, the rotational runout of the rotary grindstone is reduced, and the surface of the abrasive grain layer is, for example, 3 to 4 μm (Rma
x) By performing dressing below, it is possible to shorten the processing cycle time at the time of startup when using a new grindstone, and to greatly improve processing accuracy and processing efficiency.

[0021]

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

FIG. 1 shows a centering machine for mounting an optical element member centering grindstone according to an embodiment, which comprises a fixed lens holder 1 and a movable lens holder 2 which are arranged coaxially. The fixed lens holder 1 is integrally connected to a spindle having a hollow portion, and the spindle is
It is rotatably supported by. The hollow portion of the spindle is connected to a vacuum source by a nipple, and generates a vacuum attraction force for attracting the lens to the lens contact portion 1a of the fixed lens holder 1. Further, a spindle integrated with the movable lens holder 2 is rotatably supported by a bearing 22.

The rotation drive unit for rotating both lens holders 1 and 2 controls the rotation of the drive shaft of the motor to the fixed side lens holder 1.
And a gear train for transmitting the rotation of the drive shaft of the motor to the spindle of the movable lens holder 2.

In a lens centering step of grinding an outer diameter portion of a lens which is an optical element member, forward rotation of a motor is transmitted to both spindles, and a lens sandwiched between both lens holders 1 and 2 is applied to a grindstone 10. In the lens centering step in the process of holding the lens between the lens holders 1 and 2, the motor is rotated in the reverse direction, and the rotation is transmitted only to the spindle of the movable lens holder 2, and the fixed side is rotated. The eccentricity is corrected by rotating the movable lens holder 2 relatively to the lens temporarily held by the lens holder 1.

The axial drive unit for moving the movable lens holder 2 in the axial direction has a cylinder and a pin-on-rack mechanism for transmitting the linear movement of the piston of the cylinder to the bearing 22 of the movable lens holder 2.

The drive unit of the grindstone 10, which is a centering grindstone (rotary grindstone) of the optical element member, includes a slider 10a in the feed direction and a slider 10b in the axial direction, which are arranged on the upper surface of the base 5 which is a support for the centering machine. , A grinding wheel rotating unit 10c, and the like, and the grinding wheel rotating unit 10c includes a belt driving unit 10f and the like for transmitting the rotation of the motor 10d to a spindle 10e as a grinding wheel mounting unit.

The base 5 has a notch 5a for mounting the lens holder grinding / polishing unit 6 shown in FIG. 1B with screws or the like as mounting means.

The lens holder grinding / polishing unit 6 is used in the step of grinding and polishing the lens contact portions 1a and 2a of the fixed lens holder 1 and the movable lens holder 2, and is provided with a cutout 5a of the base 5. It is configured to be detachable.

In the above-described lens centering process, if the lens contact portions 1a and 2a of the lens holders 1 and 2 have eccentricity or the like, accurate centering cannot be performed. If the sliding resistance when sliding the lens by pressing the lens contact portions 1a, 2a of the lens holder 2 on the lens is large, it takes time to center the lens, and in addition, the lens contact portions 1a, 2a is easily damaged. Furthermore, troubles such as damage to the lens due to the leading edges of the lens contact portions 1a and 2a occur. Then, with the lens holders 1 and 2 attached to each spindle, the lens holders 1 and 2 are rotated by the lens holder grinding and polishing unit 6.
Are ground and polished to obtain the inner diameter of the lens contact portions 1a and 2a and the surface roughness 1 μm (Rm
ax) A step for performing mirror finishing and the like are provided below.

As shown in FIG. 2, the grindstone 10 has an annular centering portion 12a formed at the center of the cylindrical surface of the grindstone main body 11.
And a pair of inclined chamfers 12b protruding on both sides thereof,
In the lens centering process, first, the grindstone 10 is moved perpendicularly to the rotation axis of the lens (not shown) with respect to the rotating lens (not shown), and the centering portion 12 is moved.
a is brought into contact with the outer peripheral edge of the lens. Thereby, the outer peripheral edge of the lens is ground so as to be a perfect circle centered on the optical axis.

Subsequently, the grindstone 10 is moved parallel to the optical axis of the lens (transverse feed), and chamfering is performed with one chamfered portion 12b abutting on one side of the lens. Further, if necessary, the grindstone 10 is moved in the direction of the optical axis of the lens in a direction opposite to the above, and the other chamfered portion 12c is chamfered by contacting the opposite side surface of the lens.

The centering of the lens generally includes centering by grinding the outer peripheral edge of the lens and chamfering the side edge of the outer peripheral portion.

The lens centering process required for a high-precision lens system requires not only extremely high outer shape accuracy of the lens but also polishing of the outer surface of the lens to a surface roughness of 3 to 4 μm (Rmax).

Centering portion 12a and double-sided portion 1 of grinding wheel 10
2b and 12c adhere an abrasive layer 14 by a known method such as electrodeposition to an abrasive layer fixing surface 13 which is an abrasive layer support surface formed by cutting a cylindrical surface of the grindstone main body 11 with a machine tool such as a lathe. Formed. After the abrasive layer 14 is formed by electrodeposition, the surface, that is, the centering portion 12 is formed.
a and dressing for adjusting the machined surfaces of the both-side chamfers 12b and 12c to an appropriate surface roughness. This is a whetstone 10
The roughness of the polished surface of the lens polished by the above method is such that the target surface roughness is 3 to 4 μm (Rm
This is for adjusting the roughness of the processing surface of the grindstone 10 so as to be close to ax), whereby the processing time (processing cycle time) at startup can be reduced.

The main body 11 of the grindstone 10 is provided with the abrasive grain fixing surface 1.
3 is a radial reference surface 15a, which is a pair of first reference surfaces cut in the same processing step as the cutting process.
And a thrust reference surface 15b, which is a pair of second reference surfaces. Each radial reference surface 15a is a cylindrical surface of a small width formed so as to be coaxial with the rotation center 0 of the grindstone 10, and each thrust reference surface 15b is perpendicular to the rotation center 0 of the grindstone 10. It is an annular end face formed so that it becomes.

These reference surfaces 15a, 15b
0 is attached to the spindle 10e of the centering machine, and is used as a reference for measuring the rotational runout of the grindstone 10. The radial reference surface 15a or the thrust reference surface 1
5b or both are used to measure the rotational runout of the grindstone 10 and adjust the rotational accuracy and the like of the spindle 10e so that the rotational runout of the grindstone 10 in the radial and thrust directions when polishing the lens is 10 μm or less. To be reduced.

By adjusting such rotational runout, it is possible to prevent troubles such as damage to the polished surface of the lens due to chipping. As a result, it is possible to further shorten the processing time at the time of start-up after replacing with a new grindstone, and to further extend the life of the grindstone.

It is to be noted that, by adjusting a mounting portion of the grindstone 10 with respect to the spindle 10e and the like, rotation runout is reduced, and
Alternatively, a processing device such as a lathe used for processing the new grindstone 10 may be adjusted instead.

FIG. 3 shows a modification in which the arrangement of the centering portion and chamfering portion of the grindstone and each reference surface is changed.

The grindstone 30 shown in FIG. 3A has a recess 35c formed of a radial reference surface 35a and a thrust reference surface 35b at both end surfaces of the grindstone main body 31, respectively. The grindstone 40 shown in FIG.
It has a pair of chamfered portions, and a radial reference surface 45a and a thrust reference surface 45b are provided on both end surfaces of the grindstone main body 41. The grindstone 50 shown in FIG. And 2
It has a pair of chamfered portions, and has a recess 55c formed of a radial reference surface 55a and a thrust reference surface 55b on both end surfaces of the grindstone main body 51, respectively.

As shown in FIG. 2, the grindstone 10 holds the grindstone main body 11 between a pair of flange members 16 and 17,
By fastening with a bolt 18, it is fixed to a shaft member 19 that is integral with one flange member 16. The shaft member 19 has a tapered hole 19a that fits into the spindle 10e of the grindstone 10.

The other flange member 17 is provided with three balance pieces 20 as balance correcting means disposed in the circumferential mounting groove 17a (see FIG. 4). Each balance piece 20 can be freely attached to an arbitrary position of the attachment groove 17a of the flange member 17 by a bolt 19a. As will be described later, a static balance unit that measures the static imbalance of the grindstone 10 using a leveling jig or a dynamic balancer that measures the dynamic imbalance of the grindstone 10 measures the imbalance during rotation. By adjusting the mounting position of each balance piece 20, the unbalance amount of the grindstone 10 is reduced to 5 gf or less.

After the amount of unbalance has been reduced in this way, as described above, by measuring the rotational runout using the radial reference surface and the thrust reference surface, the start-up time when a new grindstone is used is measured. The processing time can be further reduced, and the life of the grindstone can be greatly extended.

Next, an embodiment will be described.

(First Embodiment) First, a grindstone main body which can be fitted between two flange members shown in FIG. 2 is manufactured.
Subsequently, the grindstone main body is sandwiched between two flange members and fastened by bolts, and attached to a spindle of a machine tool having a lathe function with a work rotation accuracy of 1 μm or less,
The centering portion and the chamfered portion of the grindstone main body are cut, and at the same time, the radial reference surface and the thrust reference surface are cut. Subsequently, masking is performed on the centering portion and the chamfered portion of the whetstone main body, and the abrasive grains are electrodeposited.

As shown in FIG. 5, the grindstone 10 is attached to the spindle 10e of the centering machine, the grindstone 10 is rotated, and the grindstone surface roughness test piece 70 is moved toward the center of rotation.
It comes into contact with the surface of the grindstone 10. Thus, the roughness of the surface 70a of the test piece ground by the grindstone 10 was measured,
If the required accuracy is not reached, dressing is performed to reduce the processed surface of the grindstone 10 to a predetermined surface roughness.

Next, the static balance unit 80 shown in FIG.
The static imbalance is measured using the following procedure.

The static balance unit 80 includes a level 80a.
Is leveled using three leveling jigs 80b based on the reference.

The whetstone 10 has a static balance shaft 80c.
Incorporate.

The grindstone 10 incorporating the static balance shaft 80c is mounted on the horizontal plates 80d and 8 of the static balance unit 80.
0e, the unbalance position is confirmed, and the unbalance amount is removed using a balance piece.

Finally, the spindle 10e of the centering machine shown in FIG.
, A dial stand or the like equipped with a dial indicator (1 μm / div) or the like is fixed to the bearing of the spindle 10 e or the bearing 22 of the movable lens holder 2, and the radial reference surface 15 a of the grindstone 10 and the thrust reference are fixed. Rotational runout is measured using the surface 15b, and the spindle 10e is set so that the rotational runout in at least one of the radial direction and the thrust direction is 10 μm or less.
Adjust the rotation accuracy of.

When the measured rotational runout exceeds 10 μm, a method of checking and adjusting the rotational accuracy of the work of the machine tool for cutting the grinding wheel body may be adopted.

FIG. 9 shows the processing data according to the first embodiment. The processing conditions are as follows: lens shape: biconcave lens, lens diameter: φ25, Z coefficient: 0.2, degree of wear: 65, adjustment by balance piece FIG. 7 is a graph showing the results of examining the roughness of the polished surface of the lens and the processing time from the start-up after the replacement with a new grindstone, in which the unbalance amount after: 5 gf, the processing surface of the grindstone: electrodeposited abrasive grains. The roughness of the polished surface of the lens is
The test was performed using a carbon test piece.

The roughness of the polished surface of the lens and the roughness of the processed surface of the grindstone at points A, B, C and D in the graph of FIG. 9 are as shown in Table 1 below.

[0055]

[Table 1] FIG. 11 shows processing data according to one conventional example. The processing conditions are as follows: lens shape: biconcave lens, lens diameter: φ2
5, Z coefficient: 0.2, abrasion degree: 65, unbalance amount after adjustment by balance piece: 10 gf, working surface of grinding stone: electrodeposited abrasive, lens from start-up after replacement with new grinding stone 4 is a graph showing the result of examining the roughness of the polished surface and the processing time.

Table 2 below shows the roughness of the polished surface of the lens and the roughness of the processed surface of the grindstone at points A, B, and C in the graph of FIG.

[0057]

[Table 2] The effect of the present embodiment is clarified as follows as compared with the conventional example.

Since the start of use of the new grindstone, the number of machining is 100
The total processing time for up to 00 pieces is about 1/2 that of the conventional method.
It can be shortened to the following.

The tool life of the grindstone is 1.5 times longer than the conventional one.
Could be doubled.

With the extension of the tool life of the grindstone, it has become possible to reduce the tool cost and the machining cost.

(Second Embodiment) It is generally difficult to always maintain a constant rotation accuracy of the spindle of a grindstone. Therefore, in order to remove the dynamic imbalance amount when the grinding wheel is mounted on the spindle of the centering machine, using a dynamic balancer 82 of model SB-7002 manufactured by Sigma Electric Co. of FIG.
The acceleration sensor 82a provided in this device is
0 and fixed to the bearing of the spindle 10e.
2 is provided on the side surface of the shaft member 19 of the grindstone 10 so as to measure the rotation of the grindstone 10.

The grinder 10 is rotated by the motor 10d, and the balancer is operated by the rotation of the grindstone 10, whereby the controller & monitor 82 of the balancer is operated.
In step c, the balance position and the amount of unbalance are displayed, and the balance piece 20 of the grindstone 10 is moved to the designated position and fixed with bolts.

Alternatively, using a dynamic balancer 83 of model VM-20 manufactured by Balance System Co., Ltd. shown in FIG. 8, the acceleration sensor 83a provided in this apparatus is fixed to the bearing of the spindle 10e of the grindstone 10, and this balancer is used. The rotation sensor 83b provided is provided on the side surface of the shaft member 19 of the grindstone 10 so that the rotation of the grindstone 10 can be measured.

The balance piece unit 83c of the present balancer is fixed to the grindstone 10, and the balance piece unit 83c
The balance piece 83d is arranged in the inside, and the balance piece 83d can be moved to an arbitrary position and fixed by an instruction from the controller & monitor 83e of the balancer.

The grinder 10 is rotated by the motor 30d, and the balancer is operated by the rotation of the grindstone 10, whereby the controller & monitor 83 of the balancer is operated.
The balancer 83d is displayed on the unbalance position and the amount of unbalance, and the balance piece 83d is moved to an arbitrary position and fixed according to an instruction from the controller & monitor 83e of the balancer.

In this way, the dynamic imbalance of the grindstone is reduced. Other points are the same as the first embodiment.

FIG. 10 shows processing data according to the second embodiment. The processing conditions are as follows: lens shape: biconcave lens, lens diameter: φ25, Z coefficient: 0.2, abrasion degree: 65, after adjustment by balance piece Is a graph showing the results obtained by examining the roughness of the polished surface of the lens and the processing time from the time of startup after replacement with a new grindstone.

The roughness of the polished surface of the lens and the roughness of the processed surface of the grindstone at points A, B, C and D in the graph of FIG. 10 are as shown in Table 3 below.

[0069]

[Table 3] The effect of the present embodiment is clarified as follows as compared with the conventional example.

Since the start of use of the new grindstone, the number of machining is 100
Total machining time up to 00 pieces is about 1/3 of the conventional method
It can be shortened to the following.

Since the start of use of the new grindstone, the number of machining is 100
The machining time for 00 or later can be reduced by 25% compared to the conventional method.

The tool life of the grindstone could be extended 1.5 times as compared with the conventional one.

With the extension of the tool life of the grindstone, the tool cost can be reduced and the machining cost can be reduced.

[0074]

Since the present invention is configured as described above, it has the following effects.

The loss during startup when using a new grindstone can be reduced, and the processing accuracy and processing efficiency in the centering step for lenses and the like can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a centering machine according to an embodiment.

FIG. 2 is an enlarged partial sectional view showing a part of a grindstone of the apparatus of FIG.

FIG. 3 is a diagram showing three modified examples.

4 (a) is a side view showing three balance pieces, and FIG. 4 (b) is a cross-sectional view taken along line AA of FIG. 4 (a).

FIG. 5 is a view showing an apparatus for measuring the roughness of a processed surface of a grindstone.

FIG. 6 is a diagram illustrating a static balance unit.

FIG. 7 is a diagram illustrating a dynamic balancer.

FIG. 8 is a diagram illustrating another dynamic balancer.

FIG. 9 is a graph showing processing data of the first embodiment.

FIG. 10 is a graph showing processing data of the second embodiment.

FIG. 11 is a graph showing processing data according to a conventional example.

FIG. 12 is a partial cross-sectional view showing a part of a conventional grindstone.

[Explanation of symbols]

 Reference Signs List 1 movable lens holder 2 fixed lens holder 5 base 10, 30, 40, 50 grindstone 10d motor 10e spindle 11, 31, 41, 51 grindstone main body 12a core section 12b, 12c chamfer section 15a, 35a, 45a, 55a Radial reference surface 15b, 35b, 45b, 55b Thrust reference surface 16, 17 Flange member 19 Shaft member 20 Balance piece

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C034 AA01 BB32 BB62 BB77 CA24 CB01 DD20 3C047 AA10 AA31 CC11 FF01 FF11 3C049 AA03 AA09 AA19 AB04 AC02 BA07 CA01 CB01 CB03 CB10

Claims (10)

[Claims] 1. A grindstone used for a centering step of an optical element member, comprising: a grindstone main body having a reference surface for measuring rotational runout in a predetermined direction and an abrasive grain layer support surface; An optical element member centering whetstone comprising an abrasive layer attached to the abrasive layer support surface. 2. The whetstone main body has a first reference plane for measuring radial run-out and a second reference plane for measuring thrust rotational run-out. 2. An optical element member centering whetstone according to 1. 3. An optical element member centering whetstone according to claim 1, wherein the reference surface of the whetstone main body and the abrasive grain layer support surface are formed by the same processing step. 4. An optical element member centering whetstone according to claim 1, wherein the whetstone main body is provided with balance correcting means for reducing imbalance during rotation. 5. An optical element member centering whetstone according to claim 1, wherein the unbalance amount during rotation is corrected by a balance correcting means to be 5 gf or less. 6. The grinding wheel for optical element members according to claim 1, wherein the grinding wheel is mounted on the centering machine such that a rotational runout in a predetermined direction is 10 μm or less. 7. A centering machine attached to a centering machine so that rotational run-outs in a radial direction and a thrust direction are each 10 μm or less.
Item 6. An optical element member centering whetstone according to item 7. 8. The step of preparing an optical element member centering whetstone according to claim 1, wherein the prepared optical element member centering whetstone is mounted on a centering machine and rotated to set a reference surface. A centering method comprising: a step of measuring rotational runout by using the method; and a step of adjusting a grindstone mounting portion of the centering machine so as to reduce the measured rotational runout. 9. The centering method according to claim 8, further comprising the step of adjusting a processing device for a grindstone main body of the new grindstone based on the measured rotational runout. 10. The method according to claim 1, further comprising a step of dressing the abrasive layer of the optical element member centering whetstone to a predetermined surface roughness. 9. The centering method according to 9.