KR100757627B1 - Lens grinding method and lens grinding apparatus - Google Patents

Abstract

An object of the present invention is to propose a lens grinding method capable of efficiently cutting a cutting material and processing a spherical lens surface having a small curvature with high precision.

In order to solve the said subject, in the lens grinding apparatus 1 of this invention, the tool tray 4 for lens grinding in which the grinding surface 4a becomes a spherical surface is made into the spherical core ( It rotates about the rotation center line 4A passing through the ball (O), and at the same time, the rotation center line 4A causes the centripetal oscillation so as to draw a cone surface with the vertex as the vertex, and the lens material ( W) is sent out at a predetermined feed speed in the feed direction 5A passing through the centripet O, pressurized to the tool tray grinding surface 4a that is rotating and centripetally swinged, and the lens pressed on the tool tray 4. The lens material W is ground while the material W is fed at a predetermined cutting feed rate, and the cutting feed rate is changed according to the feeding amount of the lens material.

Description

Lens grinding method and lens grinding device {LENS GRINDING METHOD AND LENS GRINDING APPARATUS}

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram which shows the principal part of the grinding apparatus of the spherical glass lens which applied this invention.

It is explanatory drawing which showed the grinding | polishing operation by the grinding apparatus of FIG.

3 is an explanatory diagram showing grinding by a conventional spherical formation method.

* Description of the symbols for the main parts of the drawings *

1: lens grinding device 3: lens holder

4: Tool Tray 4a: Spherical Grinding Surface

4A: center line of rotation of the tool tray 5: lens spindle axis

5A: lens rotation center line 20: workpiece lifting mechanism

21: horizontal arm 31: centripetal oscillator

33: support plate 33a: toroidal inner peripheral surface

33b: compressed air jet hole or groove 35: swing width adjusting unit

36A: rotation center line 37: swing angle adjustment unit

W: Lens Material O: Centripetal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens grinding method and a lens grinding apparatus for grinding an optical spherical lens. More particularly, the spherical lens can be ground with high precision without generating uneven wear in a tool tray. In addition, the present invention relates to a lens grinding method and a lens grinding apparatus capable of performing grinding processing efficiently in a short time.

As a grinding method of an optical spherical lens, a spherical surface forming method using a cup grinding wheel is widely known. According to this method, as shown in FIG. 3, the spherical surface of the cup-like grindstone 103 which rotates around the axis 102 to the glass raw material 101 which becomes the object of processing which rotates around the axis 100 is centered. Grinding is performed while pressing the grinding surface 104 to form a spherical surface 105 having the intersection of the axes 100 and 102 as the center. Although this processing method is a complete spherical surface formation method, there exist problems, such as a curvature error by the wear of the cup-like grindstone 103, and the ungrinded part generate | occur | produced in the grinding surface center part of the glass material 101.

The applicant of the present application has proposed a diamond tool rocking rotary lens grinding method in JP-A 2003-340702. By employing the lens grinding method disclosed herein, the problem arising in the spherical surface formation method by the cup grinding wheel can be solved. In particular, when grinding the lens surface having a large curvature, there is also an advantage that the curvature deviation in the obtained lens surface can be made relatively small.

However, when grinding a lens surface with a small curvature, the tolerance of curvature is narrow as the curvature is small. For this reason, even when the said lens grinding method proposed by the applicant of this application is used, there exists a problem that the precision of a lens surface falls due to the slight uneven wear of a tool tray.

In addition, when using the cutting material obtained by cutting the rod-shaped material which has a rectangular cross section as a lens material to be processed, the cutting amount will change significantly with progress of grinding processing. That is, at the beginning of the cutting process, as shown in Fig. 2A, since only both ends of the lens material contact the grinding surface of the tool tray, the cutting amount is small. As cutting progresses, as shown in Fig. 2B, both end portions of the lens material are cut into spherical shapes, and the surface is brought into surface contact with the grinding surface of the tool tray, thereby increasing the cutting amount. In the final stage of cutting, as shown in Fig. 2C, the machining surface of the lens material becomes spherical, and the machining surface is brought into surface contact with the grinding surface of the tool tray as a whole. do. However, conventionally, machining is performed at the same cutting speed, and no consideration has been given to this point, and loss occurs in the machining time.

Disclosure of the Invention An object of the present invention is to propose a lens grinding method and a lens grinding apparatus that can process a spherical lens surface having a small curvature with high precision.

Another object of the present invention is to propose a lens grinding method and a lens grinding apparatus capable of efficiently cutting a cutting material and processing a spherical lens surface having a small curvature with high precision.

In order to solve the above problems, the lens grinding method of the present invention,

A lens grinding tool tray having a grinding surface is spherical, is rotated about a rotation center line passing through the center of the sphere, and at the same time, the rotation center line pivots so as to draw a cone surface with the center as the vertex,

The lens material is sent out at a predetermined feed speed in the conveying direction passing through the centripet, pressurized to the grinding surface of the tool tray which is rotating and centripetal swinging,

Grinding the lens material while feeding the lens material pressed into the tool tray at a predetermined cutting feed rate,

The cutting feed speed is changed according to the feeding amount of the lens material.

In the lens grinding method of the present invention, the lens material is ground with a tool tray having a spherical grinding surface, while the rotational center line draws a conical surface with the center of the spherical grinding surface as the vertex. By swinging the tool tray in this manner, the spherical lens surface having a small curvature can be processed with high precision. In addition, the cutting feed rate is changed according to the feeding amount of the lens material. For example, in the case of grinding a spherical lens surface on a cutting material having a rectangular cross section, the cutting amount is small at the beginning of the processing, so that it is sent out at a high feed rate, and after a certain amount of cutting has been carried out, it is sent out at a slower feed rate. If it does so, it can process efficiently.

In this case, the cutting feed speed may be steplessly decelerated or decelerated stepwise according to the feed amount. Generally, what is necessary is just to make the said cutting feed speed into a 1st speed until the said feed amount reaches a predetermined quantity, and to switch to a 2nd speed slower than a 1st speed after that.

In this case, the machining start position can be set accurately by sending out the lens material and detecting the position where it touches the tool tray prior to the grinding process. Moreover, based on the said processing start position, while setting the switching position of the said cutting feed speed, and setting the position calculated | required by adding a machining allowance to the said processing start position as a machining completion position, waste of processing time is eliminated, Efficient grinding can be realized.

In order to detect the processing start position with high accuracy, the workpiece transfer table for dispensing the lens material is joged toward the tool tray, and after confirming that the lens material is in contact with the tool tray, the workpiece is transferred. The jog transfer of the table may be stopped, and then, the workpiece transfer station may be returned to the ultra low speed in the direction away from the tool tray, and the position at the moment when the lens material is separated from the tool tray may be set as the machining start position.

Here, the tool tray is supported in a rotatable state by a centripetal oscillator, and a spherical shape supporting the center of the grinding surface of the tool tray with the outer circumferential surface as the spherical surface of the spherical oscillator as a spherical surface. It is preferable to place on the surface, to supply the compressed air between the outer peripheral surface and the support surface to float the centripetal oscillator, and to maintain the injured state.

In this way, when the centrifugal oscillator is floated by the compressed air, the resistance during the oscillation can be greatly reduced, and the wear on the support surface can also be suppressed. Therefore, the centripetal oscillator can be smoothly and smoothly centripetally shaken. As a result, the tool tray supported thereon can be accurately centripetally shaken, so that the spherical lens surface can be processed with high precision.

On the other hand, the present invention relates to a lens grinding device for grinding a lens material by the above grinding method, the lens grinding device according to the present invention,

A tool tray having a spherical grinding surface,

A tool tray spindle supporting the tool tray in a rotatable state about a center of rotation passing through the center of the grinding surface;

A centrifugal oscillator supporting the tool tray spindle,

A swinging mechanism for causing the centripetal oscillator to oscillate so that the center line of rotation of the tool tray rotates on a cone surface having the center as the vertex;

A tool tray rotating mechanism for rotating the tool tray spindle about the center of rotation;

Lens holder which keeps lens material targeted for processing,

A workpiece transfer mechanism for sending the lens holder along a transfer axis passing through the centroid;

A workpiece rotating mechanism for rotating the lens holder around the feed axis;

It has a numerical control unit for numerically controlling the transfer operation of the lens holder by the workpiece transfer mechanism,

The numerical control unit is characterized in that the cutting feed speed of the lens material held in the lens holder is changed in accordance with the feeding amount of the lens material.

The numerical control unit is characterized in that the cutting feed rate is set to the first speed until the feed amount reaches a predetermined amount, and thereafter, the numerical control unit switches to the second speed which is slower than the first speed. have.

In addition, the lens grinding apparatus of the present invention includes a support plate for supporting the centrifugal oscillator in a state capable of oscillation, and a compressed air supply mechanism, wherein the centrifugal oscillator has a spherical outer circumferential surface,

The support plate has a spherical annular inner circumferential surface centered on the center of the grinding surface of the tool tray, and compressed air is supplied between the outer circumferential surface and the annular inner circumferential surface by the compressed air supply mechanism. A centripetal oscillator is held in a state of being floated from the annular inner circumferential surface of the support plate.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the grinding apparatus of the optical spherical lens to which this invention is applied is described, referring drawings.

1 is a schematic configuration diagram showing a main part of a grinding device of an optical spherical lens according to the present embodiment. Referring to this drawing, the grinding apparatus 1 includes the lens holder 3 for holding the lens material W to be processed and the lens material W held by the lens holder 3. It has the tool tray 4 provided with the spherical grinding surface 4a to grind.

The lens holder 3 is fixed to the lower end of the vertical lens axis spindle 5 in a state where the holding surface 3a is held horizontally so as to face downward. At the center of the lens axis spindle 5 is formed a suction passage 5a extending in the axial direction, the lower end of which is opened to the center of the holding surface 3a of the lens holder 3, the upper end of which rotates. It is connected to the suction side of the vacuum generator 8 via the joint 6 and the air filter 7. By suctioning the suction passage 5a by the vacuum generator 8, the lens material W is adsorbed and held by the holding surface 3a of the lens holder 3.

The lens spindle shaft 5 is coaxially disposed inside the cylindrical vertical holding container 9 whose upper end is sealed, and the vertical holding container is rotatable through a pair of upper and lower bearings 10 and 11. It is supported by (9). In addition, the lens spindle shaft 5 is driven to rotate around the lens rotation center line 5A, which is its vertical center line, by the lens shaft rotation motor 12. An air cylinder 13 is connected to the upper end of the vertical holding cylinder 9, and the air cylinder 13 is fixed inside the support cylinder 14 in which the upper end is sealed. The vertical cylinder 9 is pressurized downward by the air cylinder 13 by a predetermined force.

The lens spindle shaft 5 is moved up and down by the workpiece conveyance mechanism 20. The workpiece conveyance mechanism 20 is provided with the horizontal arm 21, The vertical holding cylinder 9 is inserted in the coaxial state to the vertical cylindrical part 22 attached to the front-end | tip of this horizontal arm 21, , The support cylinder 14 is fixed to the upper surface of the horizontal arm 21. The horizontal arm 21 is moved up and down along the vertical linear guide 26 by a lifting mechanism provided with a feed screw 23, a nut 24, and a servo motor 25.

Here, in the support cylinder 14 which supports the lens spindle shaft 5 via the air cylinder 13, the proximity sensor for detecting the upper end 9a of the vertical holding cylinder 9 mounted in the inside ( 27) is attached. Typically, the proximity sensor 27 is in an off state, and when the vertical holder 9 is raised relative to the support cylinder 14, the upper end 9a of the proximity sensor 27 is connected to the proximity sensor 27. Is detected, and the sensor output is turned on.

Next, as for the tool tray 4 arrange | positioned under the lens holder 3, the centroid O of the spherical grinding surface 4a is on the extension line of the lens rotation center line 5A of the lens holder 3 side. It is arranged to be located. A spindle 4b is integrally formed on the rear surface of the tool tray 4, and the spindle 4b is supported in a rotatable state by a centrifugal oscillator 31. As shown in FIG. Here, the spindle 4b is a centripetal oscillator so that the center of rotation 4A of the tool tray 4 intersects at an acute angle θ with respect to the lens center of rotation 5A extending vertically in the center of gravity O. It is supported by (31).

The centrifugal oscillator 31 has a hemispherical cup portion 31a and a cylindrical portion 3lb protruding radially outward from the outer peripheral surface portion of the bottom center of the cup portion 31a. The spindle 4b is rotatably attached to 3 lb) in a coaxial state. Moreover, the flange 31c extends in the horizontal direction from the lower end part of the cylindrical part 3lb, and the spindle drive motor 32 is mounted here.

The cup part 31a of the centrifugal oscillator 31 is supported by the annular inner circumferential surface 33a formed in the support plate 33 in a state capable of centripetal oscillation. The annular inner circumferential surface 33a is a spherical surface having the center of gravity O as the center, and the cup portion 31a whose outer circumferential surface 31d is placed on this annular inner circumferential surface 33a is spherical, centering on the center of gravity O. Swinging is possible. In this example, the compressed air ejection hole or the groove 33b is formed in the annular inner circumferential surface 33a, and the compressed air is supplied through the compressed air supply path 33c. Therefore, the cup part 31a is maintained in the state which floated from the annular inner peripheral surface 33a. Therefore, the centripetal oscillator 31 can be smoothly oscillated around the centripet O. As shown in FIG.

The lower end of the centrifugal oscillator 31 is connected to the output shaft of the electric motor 36 through the link joint 34 and the swing width adjustment unit 35, and thus the link joint 34, the swing width adjustment unit 35 and the motor. 36 constitutes a rocking mechanism that participates in rocking of the rocking body 31. The connection point 34a of the centrifugal oscillator 31 and the link joint 34 is located on the extension line of the tool tray rotation center line 4A, and the rotation center line 36A of the electric motor 36 always faces the center (O). It is kept in a state. When the adjustment knob 35a of the swing width adjustment unit 35 is operated, the distance between the connection point 34a and the rotation center line 36A of the electric motor 36 is changed. Therefore, the rocking width of the rocking motion of the centrifugal rocking body 31 can be adjusted.

Next, the electric motor 36 is supported by the swing angle adjustment unit 37. The swing angle adjustment unit 37 is provided with the cam-shaped cam 38 arrange | positioned at the fixed position, This cam 38 has the circular arc shape centering on the centroid (O). The support member 39 is attached in the state which can slide along the said cam 38, and the electric motor 36 is attached to this. The nut 40 is fixed to the support member 39, and the feed screw 41 is screwed to the nut 40. An end of the feed screw 41 is connected to the handle 42.

When the handle 42 is turned, the support member 39 moves along the cam 38. That is, the tool tray spindle 4b supported by the centrifugal oscillator 31 oscillates by a predetermined amount around the centripet O. As shown in FIG. Therefore, the swing angle adjustment unit 37 can change the angle θ formed by the rotation center line 4A of the tool tray 4 with respect to the vertical lens rotation center line 5A, that is, the angle of the swing center line. .

Here, drive control of each part is performed by the numerical-control controller 50. As shown in FIG. In addition, the input device 51 is connected to the controller 50. Through the input device 51, the operation of sending out the lens material by manual operation is possible, and it is possible to set the cutting amount and the like.

With reference to FIG. 2, the operation | movement of the lens grinding apparatus 1 of this structure is demonstrated. First, the lens material W is attracted to and held by the lens holder 3. Then, the servo motor 25 is driven by manual operation, and the lens material W is transferred to the tool tray 4 by the jog JOG. When the lens material W is in contact with the tool tray 4, the lowering of the lens axis spindle 5 is stopped. Next, only the horizontal arm 21 (workpiece conveying table) descends by jog conveyance. As a result, the lens axis spindle 5 and the vertical holder 9 rotatably supporting it rise relative to the horizontal arm 21, and the proximity sensor 27 of the vertical holder 9 The upper end 9a is detected and turned on.

After confirming that the proximity sensor 27 is turned on, jog transfer is stopped once. Then, the feed speed of the servo motor 25 is made into the ultra low speed, and the horizontal arm 21 is raised. When the horizontal arm 21 ascends, the stationary lens spindle axis 5 and the vertical holder 9 lower relative to the proximity sensor 27. As a result, the upper end 9a of the vertical holding container deviates from the detection position of the proximity sensor 27, and the proximity sensor 27 returns to off again. The controller 50 stores the position at the moment when the switch is turned off as the machining start position.

The controller 50 adds a machining allowance from the machining start position to set a machining completed position. Moreover, only a 1st cutting amount is added to a machining start position, and a speed change point is set. After setting each point in this way, when a process start command is input, rotation of the lens material W fixed by suction to the tool tray 4 and the lens holder 3 will be started. Then, the lens material W is sent out to the machining start position at a high speed.

After the machining start position is reached, the speed is switched to the first cutting speed, and grinding is performed while feeding the lens material W at this speed. FIG.2 (a) has shown the state at the time of starting grinding.

After the lens material W is cut by the first cutting amount to reach the first cutting position, that is, after reaching the cutting state as shown in Fig. 2B, the swinging of the centripetal oscillator 31 is performed. The cutting is started while cutting the lens material W at a finishing speed slower than the first cutting speed. As a result, the lens material W is ground, and as shown in Fig. 2C, a spherical lens surface Wa is formed.

When it is confirmed that the machining completion position has been reached, the shaking by the centripetal oscillator 31 is stopped, and then the horizontal arm 21 is raised to the upper end position. Then, the rotation of the tool tray 4 and the lens material W is stopped.

In the lens grinding method and the lens grinding apparatus of the present invention, the lens material is subjected to a centripetal fluctuation while the tool tray including the spherical grinding surface draws a concentric surface whose center of rotation is the vertex of the spherical grinding surface. By swinging the tool tray in this manner, the spherical lens surface having a small curvature can be processed with high precision.

In addition, the cutting feed rate is changed according to the feeding amount of the lens material. For example, in the case of grinding a spherical lens surface on a cutting material having a rectangular cross section, the cutting amount is small at the beginning of the processing, so that it is sent out at a high feed rate, and after a certain amount of cutting has been carried out, it is sent out at a slower feed rate. Doing. Therefore, no waste is generated in machining time, and the spherical lens surface can be efficiently cut.

In addition, the starting position of cutting process is correctly grasped | ascertained and based on this, the switching time point of a cutting feed speed and the cutting completion time point are set. As a result, the spherical lens surface can be efficiently cut without wasting processing time.

And the centrifugal oscillator which supports the tool tray rotatably is supported in the state which floated by the compressed air. Therefore, the resistance at the time of oscillation of a centrifugal oscillator can be reduced significantly, and the abrasion of the support surface can also be suppressed. Therefore, since the tool tray supported by the centrifugal oscillator can be precisely centripetally oscillated, the effect of machining the spherical lens surface with high accuracy can be obtained according to this.

Claims (8)

The lens grinding tool tray 4 whose grinding surface 4a is spherical is rotated about the rotation center line 4A which passes through the spherical center O, and the said rotation center line 4A is the said Centripetal oscillation to draw a cone with the center of gravity (O) as the vertex, The lens material W is sent out at a predetermined feed speed in the conveying direction passing through the centripet O, and is pressed against the grinding surface 4a of the tool tray 4 that is rotating and centripetally swinged, The lens material W is ground and processed while feeding the lens material W pressed on the tool tray 4 at a predetermined cutting feed rate, The said cutting feed speed is made into a 1st speed until the said feed amount reaches a predetermined quantity, and after that, it switches to the 2nd speed slower than a 1st speed, The lens grinding method characterized by the above-mentioned. delete The method of claim 1, Prior to the grinding process, the lens material W is sent out to detect a position of touching the tool tray 4, Set the position as the machining start position, And a position obtained by adding a machining allowance to the machining start position, as a machining completion position, while setting the switching position of the cutting feed speed based on the machining start position. The method of claim 3, wherein At the time of detection of the said processing start position, The workpiece conveyance table 21 for discharging the lens material W is jog-feeded toward the tool tray 4, and after confirming that the lens material W is in contact with the tool tray 4, the workpiece is conveyed. Stop jog feed of the table 21, Thereafter, the workpiece transfer table 21 is returned to the ultra low speed in the direction away from the tool tray 4 to set the position at the moment when the lens material W is separated from the tool tray 4 as the machining start position. A lens grinding method characterized by the above-mentioned. The method according to any one of claims 1, 3 and 4, The tool tray 4 is supported in a rotatable state by the centrifugal oscillator 31, The outer peripheral surface 31d of the centrifugal oscillator 31 is made into a spherical surface, The outer peripheral surface 31d is placed on a spherical support surface 33a having the center of gravity O of the grinding surface 4a of the tool tray 4 as the center, Compressed air is supplied between the outer circumferential surface 31d and the support surface 33a to float the centripetal oscillator 31, Lens centrifugation characterized in that the centripetal oscillator (31) is centrifuged while maintaining the injured state. A tool tray 4 having a spherical grinding surface 5a, A tool tray spindle 4b supporting the tool tray 4 in a rotatable state about a center of rotation 4A passing through the center O of the grinding surface 4a; A centrifugal oscillator 31 supporting the tool tray spindle 4b; As a swing mechanism 34, 35, 36 for centripetally swinging the centrifugal oscillator 31 such that the rotational center line 4A of the tool tray 4 rotates on a cone surface with the vertices O as a vertex. , The link joint 34, the swing width adjustment unit 35 and the electric motor 36, and the lower end of the centrifugal swinging body 31 is connected to the link joint 34 and the swing width adjustment unit 35 by an electric motor ( Rocking mechanisms (34, 35, 36) connected to the output shaft of the cylinder 36; A tool tray rotating mechanism 32 for rotating the tool tray spindle 4b about the rotation center line 4A; A lens holder 3 for holding a lens material W to be processed, and A workpiece conveyance mechanism 20 for discharging the lens holder 3 along the conveyance axis 5a passing through the centroid O; Workpiece rotating mechanisms 5 and 12 for rotating the lens holder 3 around the feed axis; It has a numerical control unit 50 for numerically controlling the transfer operation of the lens holder 3 by the workpiece transfer mechanism 20, The numerical control section 50 sets the cutting feed rate of the lens material W held by the lens holder 3 to be the first speed until the feeding amount reaches a predetermined amount, and thereafter A lens grinding apparatus, characterized in that switching to a second speed slower than the first speed. delete The method of claim 6, A support plate 33 for supporting the centripetal swinging body 31 in a swingable state; Compressed air supply mechanism (33b, 33c), The centrifugal oscillator 31 has a spherical outer peripheral surface 31d, The support plate 33 is provided with a spherical annular inner peripheral surface 33a having the center of gravity O of the grinding surface 4a of the tool tray 4 as the center, Compressed air is supplied between the outer circumferential surface 31d and the annular inner circumferential surface 33a by the compressed air supply mechanism, so that the centripetal oscillator 31 is the annular inner circumferential surface 33a of the support plate 33. A lens grinding apparatus, which is held in an injured state from the lens.

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