JPS60114457A - Spherical face forming grinder - Google Patents

Abstract

PURPOSE:To automate the spherical face forming grinding process by correcting the setting position of cup-shaped grinding wheel with correspondence to a signal detected through a spherical face gauge provided movably thereby enabling automatic correction of gauging and setting of spherical face accuracy. CONSTITUTION:Upon reaching to specific count, gauging operation is started to rotate a gauging arm thus to position a spherical face gauge 17 onto a lens 3 then the arm is moved axially to contact the referential ring 20 of said gauge 17 against the lens face thus to gauge the differential sag of lens face. Then any one of proximity switches SW1, SW2 is turned on and if is decided to require correction, corrective position of cup-shaped grinding wheel 6 is operated by an arithmetic unit 15B on the basis of an output signal from proximity switch under on-state to turn the grinding wheel by the operated amount thereafter it is set again to work the lens face again and to complete the work upon reaching to specific count. Consequently, automation and unattended working can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a spherical surface grinding and generating device that forms a spherical surface such as a lens using a rotating cup-shaped grinding wheel.

[Background of the invention]

The 1/2-inch ground surface created by the spherical surface creation method, in which a rotating cup-shaped grinding wheel is brought into contact with the surface of a rotating lens blank to create a spherical surface, is usually created in the next step by:
Furthermore, the sand plate is polished and polished using a polishing plate.
As a result, the 1/lens surface is finally finished with a predetermined radius of curvature. In this case, the machining efficiency of the finished surface of the lens is greatly influenced by the grinding accuracy of the spherical surface created in the previous process, so extremely high precision is required for the grinding surface of the spherical surface created in the previous process. required.

In addition, in general, a cup-shaped diamond grinding wheel is used as the grinding wheel in a spherical grinding machine, so once the cup-shaped grinding wheel is centered on the lens surface, it grinds a relatively large number of 1/lens surfaces. However, the precision of the ground surface can be maintained sufficiently stably. However, the grinding surface also
The surface accuracy changes by a small amount of L2 due to the wear of the grindstone due to generation grinding of a large number of lens surfaces, thermal deformation of the spherical surface grinding generator due to continuous operation for a long time, etc. In addition, sometimes an accident such as a chuck of a lens blank may damage the grinding wheel or the like, and the surface accuracy may be seriously disrupted.

Therefore, conventionally, in the spherical surface generation grinding process, it was necessary to perform a sampling inspection on lenses whose spherical surface was generated at a certain number of cases or at a certain period of time, and each time, a dial indicator was used to inspect the lens surface of the reference lens. The error had to be measured. In addition, if the surface accuracy deviates from the specified tolerance range, the settings such as the position and angle of the cup grinding wheel relative to the 1/2-lens surface are adjusted again each time by operating the handle of the spherical grinding machine. However, it was necessary to perform trial grinding. Therefore, inspection of the grinding surface and setting of the grinding wheel have traditionally been a bottleneck in automating and unmanning the spherical surface generation grinding process.

[Purpose of the invention]

In view of the actual situation of spherical surface grinding using the above-mentioned conventional spherical surface grinding generating machine, the present invention automatically measures the spherical surface accuracy in a short time during the process of spherical surface generating grinding, and sets the grinding wheel based on the measured value. The purpose of the present invention is to provide a spherical grinding generating machine that can be automatically corrected.

[Summary of the invention]

To achieve the above object, the present invention compares a spherical surface generated by grinding with a spherical surface of a master lens having a desired radius of curvature, and determines whether the spherical surface generated by grinding is within a tolerance range. A spherical surface measuring instrument for detecting whether or not is movably provided,
The system is configured to be able to measure the 1/2-inch generating spherical surface held on the work shaft, and to move the cup-shaped grinding wheel set at a predetermined position from the set position in response to the detection signal of the spherical surface measuring device. [Embodiments] Hereinafter, embodiments of the present invention shown in the accompanying drawings will be described in detail.

FIG. 1 is a block diagram of an automatic spherical grinding generation device showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the setting of the grinding wheel in FIG. 1.

In FIG. 1, a lens 3 held by a chuck 2 provided at the tip of a work shaft 1 is rotated at low speed by a work shaft rotation motor M1 supported by a work head 4. As shown in FIG. The work head 4 is driven by a reversible work feed motor (not shown) and moves left and right in FIG. On the other hand, a cup-shaped grinding wheel 6 such as a diamond cup wheel is removably installed at the tip of the tool shaft 5.
is a grindstone rotation motor M2 supported by the sole head 7.
rotated at high speed. The tool head 7 is mounted on a rotating table 9 that can rotate around a table axis 8, and is moved by a tool head moving motor M3 via a feed screw 10 and an interlocking gear 11 to
It is constructed so that it can slide in the direction. Further, the turning table 9 is configured to turn in the direction of arrow Y by a turning table motor M4 via a worm gear mechanism 12 and an interlocking gear 13. Further, a spherical surface measuring instrument 17, which will be described in detail later, is movably provided near the chuck 2 in order to measure the precision of the ground surface of the lens whose spherical surface has been generated.

Motor M is a low speed motor, motor M2 is a high speed motor,
Both driving and stopping are controlled by the control circuit 14. Further, the tool head moving motor M3 and the turning table motor M4 are both reversible pulse motors, and are driven and controlled by pulse signals from the control circuit 14.

Furthermore, this control circuit 14 is configured to control the motors M and -M4 in accordance with an output signal from a CPU 15 including a memory unit 15, a calculating unit 15B, and a determining unit 15C. Also, the radius of curvature R8 of the desired lens surface
and the grinding diameter Dg of the cup-shaped grinding wheel (see Figure 2)
, the rotational speed of the work shaft 1 and the tool shaft 5, and other necessary data are stored in the memory means 15A via the keyboard 16.

Now, the moving direction of the tool shaft 5, that is, the moving direction of the grinding wheel 6 is the Y axis (the direction of convex surface grinding is positive, and the opposite direction is negative).

), the rotating direction of the rotating table 9, that is, the rotating direction of the grinding wheel 6, is the Y axis, and the moving direction of the work shaft 1, that is, the grinding feeding direction of the lens is the Z axis. The position of the grinding wheel 6 with respect to the Z axis is determined by a pulse signal output from the control circuit 14.

The second cup-shaped grinding wheel 6 is set in a spherical surface generating state.
In the figure, the position of the cup-shaped grinding wheel 6 is represented by (x, y), and the angle formed by the rotation axis 11 of the cup-shaped grinding wheel 6 and the work rotation axis (1/2 inch rotation axis) is y1 on the rotating table. 9 rotation center (center of rotation axis 8) 0 and workpiece rotation axis 1
2 is the distance from the rotation axis 1.2, when x=o + y=o, the rotation axis 1. and 12 match. The position of the cup-shaped grinding wheel 6 on the Z coordinate axis (rotary axis 12) in this state becomes the origin position of the grinding wheel.

On the other hand, the radius of curvature of the ground surface (finished surface) of the lens is Ro,
The radius of curvature of the edge of the cup-shaped grinding wheel 6 is rl, and the diameter of the grinding wheel at the center of curvature of the edge is Dg. These values are CP
The information is input from the keyboard 16 into the memory means 15A of U15 and stored. Also, when the midpoint of the diameter connecting the center of curvature of the edge is G, and x = 0 + y = o, the coordinates of the midpoint G and the turning center O on the two axes are Zg, Zo torst, and turning angle, respectively. The setting position (Xa, ya) of the cup-shaped grinding wheel when α is expressed by the following equation.

y,, -=sh-1Dg/(Ro+Kr) (=J-(
1) However, K is a coefficient, and when the ground surface is a convex surface, =l, and when the ground surface is a concave surface, =-1.

The above equations (1) and (2) are calculated by the calculation means 1.5B of the CPU 15, and pulse signals from the control circuit 14 based on the calculation results are used to control the tool head moving motor M3 and the turning table motor M4. is driven and controlled, and the setting of the cup-shaped grinding wheel 6 is completed.

The lens surface ground by the cup-shaped grinding wheel 6 centered as described above is measured by a spherical surface measuring device 17, which will be described later. FIG. 3 is a diagram showing the principle of spherical surface measurement.

In Fig. 3, if Ro is the standard radius of curvature of master 1/nzu, Rj is the radius of curvature of test 1/n, and Ds is the diameter of the reference ring of the spherometer for measuring spherical surfaces, then the requirements for the ground surface by the spherical surface generation method are as follows: (9) Accuracy, that is, the sag amount hs of the master lens and the test subject 1/
The difference δ (tolerable error) from the contact height ht of the lenses is δ=±5μ
m (target value).

Now, if the radius of curvature Rt of the test lens is corrected to the reference radius of curvature of the master 1/lens using the difference δ in the sag amount as the correction amount, then the change in the radius of curvature of 1/lens ΔR
(Rt-Ro) is approximately 1R=(8Ro' ”δ
)/(8Roδ10kDI)・・・・・・・・・・・・(
3). Here, Ro - target radius of curvature (radius of curvature of master 1/lens) k
-+1 (convex), -1 (concave) Ds = diameter of the measurement reference ring of the spherometer.

Also, if the amount of grinding wheel setting angle correction required to change the radius of curvature of the 1/lens by ΔR is Δθ, then from the above equation (1), (10) where Dg is the center of the edge radius of the grinding wheel. The diameter r is the radius of curvature of the edge of the cup-shaped grinding wheel.

Therefore, the setting angle correction amount Δθ is calculated from equations (3) and (4), and the motor M4 is
is driven and controlled, and the setting position of the cup-shaped grinding wheel 6 is corrected.

FIG. 4 is a cross-sectional view of the spherical surface measuring device 17 that measures whether the difference δ in the sag amount for correcting the radius of curvature of the 1/lens surface is within the allowable range. This spherical surface measuring device 17 is provided with a stylus 18 that penetrates inside a threaded portion 17B provided at the right end of the measuring device main body 17A and slides from side to side in FIG. The sliding displacement is configured to move the switch actuating member 19 from side to side via an enlargement mechanism (not shown) provided in the measuring instrument main body 17A. Two proximity switches Sw, 8w2 are provided with this switch actuating member 19 in between.

Further, the measurement reference ring 20 that is screwed onto the threaded portion 17B is configured so that the relative position between the tip of the stylus 18 and the left end surface of the measurement reference ring 20 can be adjusted, and the position is fixed by a lock nut 21. It is formed. Also,
The distance between the two proximity switches Swl and Swl is also adjustable. When one proximity switch Sw1 is activated, the 1/lens surface is too high, and when the other switch Sw2 is activated, the lens surface is too low. When there is 19, 1
/ lens surface is within the permissible range. Therefore, each time the curvature of the 1/lens surface to be machined changes, the ends of the measurement reference ring 20 and the stylus 8 are attached to the spherical surface of the master lens 3' having the desired radius of curvature, as shown in FIG. contact,
At that time, the position of the measurement reference ring 20 is adjusted so that the switch actuating member 19 is located between the proximity switches Swl and 8w2.

FIG. 5 is a front view of the autoload device section that holds the spherical surface measuring device 17, and FIG. 6 is a side view of FIG. 5. In FIG. 1, this autoload device section is omitted.

5 and 6, an autoloading device 22, a workpiece supplying device 23, and a workpiece unloading device 24 each having a rotatable loading arm 21, 21' are attached to the workhead 4, and the two loading arms are attached to the workhead 4. The arms 21 and 21' each have a lens suction device 25.
25' is provided. Further, a measuring arm 26 is provided integrally with the loading arm 21, 21', and the spherical surface measuring instrument 16 is mounted on the measuring arm 26 with an elastic member 27.
It is attached to the fuselage via etc. Further, the measuring arm 26 is provided with an air gun 28 for removing adherents such as grinding fluid and glass powder adhering to the 1/2 lens surface using a jet of air before measurement.

During the grinding process, the loading arm 2 is in the position shown in Figure 5.
1.21' and the measuring arm are constructed so that they can swing together and move to the right in FIG. In addition, in FIG. 5, the loading arms 21 and 21' rotate clockwise by about 4 f, and one of the unloading loading arms 21 is placed over the processed l/lens 3 held by the air chuck 2 of the work shaft 1. 5, the other feeding loading arm 21' is located on the workpiece feeding device, and conversely from the position shown in FIG.
When ' is rotated counterclockwise and the supply loading arm 21' is positioned above the 1/2 lens 3, the other unloading loading arm is configured to move up to above the workpiece unloading device 24.

The structure and operation of this loading device are similar to those of the conventionally known 1/2-inch loading device, so a detailed explanation thereof will be omitted.

When the supply loading arm 21' and the unloading loading arm 21 swing a predetermined number of times to feed the 17 lens blank toward the work shaft side and send the ground lens 3 to the unloading device, the loading arms 21°21' and the measurement arm 26 rotate together, and the measurement arm 26 moves up to above the lens 3 and stops.

In this state, air is injected from the air gun 28,
1/ deposits on the lens surface are removed. Next, the measuring arm 26 moves to the right in FIG. 6, the measurement reference ring 2o of the spherical surface measuring device 17 comes into contact with the spherical surface of the lens 3 as shown in FIG. Toward the center of curvature,
It touches the vertex of the sphere. At this time, when both the proximity switches Sw1 and 8w2 of the spherical surface measuring device 17 are in the OFF state, the measuring arm 26 returns to its original position and the lens is sucked by the lens suction device 25 of the loading arm 21 for carrying out. The l/lens blank is taken out and instead is sucked by the l/lens suction device 25' of the supply loading arm 21' and supplied to the work shaft.

Furthermore, if the proximity switch Swl or 8w2 is turned on, the detection signal is sent to the control circuit device 14, and the grinding wheel setting angle correction amount Δθ is calculated by equation (4), and the control circuit based on the result The motor M4 is driven by the pulse signal from the grinding wheel 14, and the position of the cup-shaped grinding wheel 6 is corrected. The 1/2 inch lens 3 is again ground to create a spherical surface by the grinding wheel 6 whose position has been corrected.

Next, the lens surface measurement and correction process in the above embodiment apparatus will be explained based on the flowchart of FIG.

When the lens blank is suctioned and held by the air chuck 2 of the work shaft 1 and the position of the cup-shaped grinding wheel 6 of the tool shaft 5 is set, the spherical surface generating grinding operation is started. A lens is ground (step 101), and each time the ground lens is carried out by the autoloading device 22, the number of processed lenses is counted by a counter (not shown) provided in the autoloading device (step 102).
It is stored in the memory means 15A of the CPU 15. Here, the determining means 15C determines whether the count number (6) has reached the total number of machinings stored in advance via the keyboard 16 (step 103). When this is reached, the processing operation is terminated.

In addition, when the count number does not reach the total number of pieces processed, the count number (company) further determines whether or not it has reached a predetermined number that is predetermined for spherical surface measurement and is stored via the keyboard 16. The determination means 15C makes a determination (step 104), and if the counted number does not reach the predetermined number, the process returns to step 101 to continue processing. When the count reaches a predetermined number to be measured, the measurement operation is started (step 105), the measurement arm 26 rotates, and the spherical surface measuring instrument 17 is positioned above the lens 3. Then, the measurement arm 26 moves in the axial direction, and the measurement reference ring 20 of the spherical surface measuring instrument 17 comes into contact with the 1/lens surface, and the difference δ in the amount of sag on the 1/lens surface is measured. This spherical surface measuring instrument 17 determines whether or not it is necessary to correct the 1-nons surface (step 1o6).

If both proximity switches Swl and 8w2 are OFF
If it is determined that there is no need to correct the surface, the process returns to step 101 to continue machining.

In addition, if either the proximity switch Swl or 8w2 is in the ON state and it is determined that correction is necessary, the calculation means 15B uses the cup shape based on the output signal from the proximity switch in the ON state. Calculation for correcting the position of the grinding wheel 6 is performed (step 107), the grinding wheel 6 is pivoted by the corrected value Δθ, and resetting is performed (step 108).

When this resetting is completed, step 101 is performed again.
The lens surface is reprocessed by returning to , and processing of yet another lens surface is continued. The number of processed pieces is counted (step 102), and when the counted number matches the total number of processed pieces, the spherical surface generating grinding operation is completed.

Note that the number of lenses processed by the time of measurement with the spherical measuring device 17, that is, the number counted by the counter, depends on the degree of wear of the cup-shaped grinding wheel, the hardness and softness of the lens material, etc.
This varies depending on the amount of grinding/cutting of the lenses, etc., and is stored in the memory means 15A via the keyboard 16 prior to the machining operation.

Furthermore, in the above embodiment, both the position setting and the correction amount of the cup-shaped grinding wheel are calculated by the CPU, and the position of the grinding wheel is adjusted based on the calculated values.
The initial position of the grinding wheel is manually set, and the position of the cup-shaped grinding wheel is set based on the value calculated by the CPU only when the position is corrected due to wear of the cup-shaped grinding wheel. Good too.

〔Effect of the invention〕

As described above, according to the present invention, a spherical surface measuring device is provided to detect whether the spherical surface of a lens created by grinding is within the tolerance range of a desired radius of curvature, and Since the cup-shaped grinding wheel correction set is used, even if the spherical surfaces of a large number of lenses are continuously created, the spherical surfaces will not deviate from the tolerance range, and work efficiency can be improved. Further, once the grinding wheel is set, the setting can be automatically corrected, so the spherical surface generation grinding process can be automated or unmanned.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the setting of the grinding wheel shown in Fig. 1, Fig. 3 is an illustration of the principle of tolerance measurement of a spherical surface, and Fig. 4 is a diagram of the setting of the grinding wheel shown in Fig. 1. An enlarged sectional view of the spherical surface measuring device in the example, FIG. 5 is a front view of the autoloading device that supports the spherical surface measuring device shown in FIG. 4, FIG. 6 is a side view of FIG. 5, and FIG. 7 is a spherical surface measuring device. It is a flowchart of measurement process work. [Explanation of symbols of main parts] 1 Work axis, 3 Lens 3' Master lens, 6 Cup-shaped grinding wheel, 15 CPU. 17 Sphere measuring instrument, Applicant Nippon Kogaku Kogyo Co., Ltd. Agent Takao Watanabe , Figure 7'5 Figure 6 JP-A-Sho GO-114457 (7)

Claims (3)

[Claims] (1) In a spherical grinding machine that automatically creates a lens surface with a desired radius of curvature by bringing a lens into contact with a cup-shaped grinding wheel set at a predetermined position, the spherical surface of the lens held on the work shaft is The present invention is characterized in that a spherical surface measuring device is provided for detecting whether or not the spherical surface measuring device is within an allowable error range, and the cup-shaped grinding wheel is configured to be corrected and moved from a set position in response to a detection signal of the spherical surface measuring device. Spherical surface generating grinding device. (2) The spherical surface measuring device (17) moves and measures the spherical surface of the lens (3) when the number of processed lenses for spherical surface creation reaches a predetermined value. When it is within the range, spherical surface creation is continued, and when it is outside the allowable range, it is configured to output a detection signal for correcting the set position of the cup-shaped grindstone (6). A spherical surface generating grinding device according to claim 1, characterized in that: (3) The spherical surface measuring instrument (17) is attached to a flexible measuring arm (26) that is provided so as to move integrally with the loading arms (21, 21) of the autoloading device (22) that feeds and ejects the lens (3). The loading arm ('21.21') is installed on the workpiece axis (1).
Claim 1, wherein the spherical surface measuring device (17) is configured to move to a position opposite to the 17 lens (3) when the lens is retracted from the position of the 1/1 lens (3). The spherical surface generating grinding device according to item 1 or 2.