JPH08356B2 - Method and device for polishing lens - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the field of polishing, and mainly relates to a polishing method and apparatus for polishing optical elements such as lenses.

[0002]

2. Description of the Related Art As a conventional technique, there are various methods for polishing a lens. When classified according to the pressing force applied to the lens, an Oscar system and a diagram in which the pressing force changes as shown in FIG. As shown in FIG. 7, there is a ball-core polishing method in which the pressing force is constant, and the target technology of the present invention relates to the latter ball-core polishing method.

In any of the polishing methods, the fundamental means in polishing is performed by friction between the lens 17 to be processed and the polishing surface of the polishing tool (polishing plate 1), and the radius of curvature of the polishing surface of the polishing plate 1 is adjusted. As long as it is the processing method of reflecting on the lens 17 to be processed, the polishing surface of the polishing plate 1 changes every moment due to various factors, and the radius of curvature of the lens 17 to be processed changes accordingly. Currently, to address this issue,
The operator corrects and restores the polishing surface of the polishing plate 1 at appropriate times while measuring the change in the radius of curvature of the processed lens. However, this correction / restoration work is a work that requires skill, has a large time loss, and has an inherent problem that an extra jig is required.

The change in the polishing surface of the polishing plate 1 is caused by the difference in the partial wear amount at a certain portion. The factors that can be cited as the causes are the pressing force P, the peripheral velocity V, and the retention. Time (it can be captured by rocking speed) ΔT,
Empirically, the product of these, that is, P · V · ΔT, is judged to be proportional to the partial wear amount.

[0005]

In view of the above, the present invention has been made.
In the spherical core polishing method in which the pressing force P is constant, the residence time Δ corresponds to the change of the peripheral velocity V of the polishing plate in the rocking means.
It is an object of the present invention to provide a lens polishing method and device capable of processing a lens having a stable radius of curvature by changing T to suppress changes in the polishing surface of the polishing plate.

[0006]

According to a first aspect of the present invention, there is provided a lens polishing method, wherein a polishing surface of a lens to be processed is brought into contact with a rotating polishing tool to press the polishing surface, and a center of a radius of curvature is used as a swing center. In the ball-core polishing method in which the polishing tool is oscillated to perform polishing, the pressing force applied per unit surface area of the polishing surface of the lens to be processed is P, and the polishing surface of the lens to be processed is in contact with the polishing tool. When the peripheral speed V of the polishing tool at the position and the relative residence time of the lens to be processed which changes due to the rocking at the position where the polishing surface of the lens to be contacted with the polishing tool are ΔT, P × V It is formed by rocking the polishing tool in a state where × ΔT = constant.

In the lens polishing apparatus of the second invention, the polishing tool is pivotally supported by the swing shaft at the center of the radius of curvature of the lens to be processed, the lens to be processed is attached to the subordinate rotary member, and the rotary member is attached. In a spherical core polishing apparatus in which a holder supporting the shaft is pressed and supported by a predetermined pressing force, the swing shaft is swung by a swing mechanism such that P × V × ΔT = constant described in the first invention. It consists of

According to a third aspect of the invention, the swing mechanism of the second aspect is
It comprises a pinion that is pivotally supported by a swing shaft, a rack that meshes with the pinion, a cam that gives a predetermined reciprocating rectilinear motion to the rack, and a drive unit that drives the cam. Here, the cam includes those arranged in a single stage to multiple stages.

A fourth aspect of the present invention is the second or third aspect of the present invention, wherein an air jet flow region is formed between the front end surface of the holder that pivotally supports the rotating body and the rotating body.

A fifth aspect of the invention is the second or third or fourth aspect of the invention, in which the weight of the holder including the rotating body is borne by the support system, and a pure pressing force is applied to the lens to be processed. .

[0011]

In the first invention and the second invention, P × V × ΔT =
The residence time ΔT is automatically adjusted with respect to the peripheral velocity V so as to be constant.
Therefore, the polishing surface of the polishing tool wears uniformly.

In the swing mechanism of the third invention, the cam changes the residence time of the polishing tool.

The air jet flow region of the fourth invention prevents wear dust from adhering to the rotating surface of the subordinate rotating body.

Removing the own weight of the holder including the rotating body of the fifth aspect of the invention ensures a pure pressing force to the lens to be processed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The lens polishing apparatus a of the present invention will be explained based on an embodiment. As shown in FIGS. 1 and 2, the rotating means of the polishing plate 1 which is a polishing tool is based on the conventional ball-core polishing method. A motor 3 and a housing 4 are attached to the swing arm 2, the lower end of a main shaft 5 pivotally supported by the housing 4 is directly connected to the motor 3, and the polishing plate 1 is screwed onto the upper end. The swing arm 2 is detachably attached to the tip end of the swing shaft 6, and the swing shaft 6 is rotatably supported by a housing 8 attached to the main body 7 of the apparatus so as to be rotatable. A pinion 9 is pivotally attached to the rear end of the device, and a rack 10 meshes with the pinion 9. The rack 10 is attached to a slide unit 11 attached to the apparatus body 7, and a cam follower is attached to one end of the slide unit 11. 12 is attached, a spring is attached to the other end, and the spring 10 pushes the rack 10 toward the cam follower 12 side.
The cam follower 12 has a cam 13 having a contour described later.
The cam shaft 14 which abuts the peripheral surface of the cam 13 and is fitted with the cam 13 is rotatably supported by a bearing unit 15, and the bearing unit 15 is attached to a pedestal 16 fixed to the main body 7 of the apparatus. The motor 3 attached to the pedestal 16 is directly connected to the rear end of the shaft 14.

Here, first, regarding the residence time ΔT corresponding to the peripheral velocity V at the position of the polishing plate 1 which is in contact with the center point of the lens 17 to be processed (hereinafter, simply referred to as the lens 17),
This will be described with reference to FIG. In general, the amount of wear caused by friction of an object is often expressed as the coefficient of friction x PV value, and the amount of wear in polishing is also this PV.
Represented as a value. Therefore, the amount of wear is proportional to the pressing force P at the abutting position and also to the peripheral speed V.
Here, when the pressing force P is constant and the abutting position moves by swinging, the peripheral speed changes from V ₁ to V ₂ . FIG.
At the center line segments OA ₁ and OA ₂ connecting the points A ₁ and A ₂ which are the centers of the polishing surface of the polishing plate 1 moved by the swing and the points O which is the center of the radius of curvature. Lens 17
Vertical lines are drawn from positions B where the center of the contact point and the polishing surface of the polishing plate 1 contact each other, and the intersection points are C ₁ and C _2, and ∠A ₁ OB =
If θ ₁ and ∠A ₂ OB = θ ₂ and the rotation number of the polishing dish 1 is N, then V ₁ = 2πN × line segment BC ₁ V ₂ = 2πN × line segment BC ₂ . Here, when the radius of curvature of the polishing surface of the polishing plate 1 is R, the line segment OA ₁ = line segment OA ₂ = R, and the line segment BC ₁ = Rsin θ ₁ line segment BC ₂ = Rsin θ ₂ . Therefore, V ₁ = 2πNRsin θ ₁ V ₂ = 2πNRsin θ ₂ , and it can be seen that the PV value represented as the amount of friction changes due to the change in the peripheral speed V due to the swing. Therefore, if the mechanism that can cancel the change in the peripheral speed V is used, the change in the polishing surface of the polishing plate 1 can be suppressed. Therefore, the present invention employs a swinging device in which the change of the residence time ΔT is inversely proportional to the change of the peripheral velocity V in a predetermined functional relationship.

That is, the rate of change ΔV of the peripheral speed V is expressed by the equation V =
In 2πNRsinθ, if 2πNR = C, then ΔV = V ′ = (Csinθ) ′ = Ccosθ. By the way, since O ≦ C cos θ ≦ C, the rate of change Δ ² T of the residence time ΔT that can cancel the rate of change ΔV is
Since ΔV + Δ ² T = C must be satisfied, Δ ² T = C−C cos θ = C (1−cos θ), as shown in FIG. However, since this change rate Δ ² T is given by the shape of the cam 13, it is equal to the change rate ΔL of the movement width of the cam 13. Therefore, ΔL = C (1-cos θ). By the way, the polishing plate 1 swings from the swing angle widths θ ₁ to θ ₂
While swinging up to, the cam 13 moves to θ ₁ as shown in FIG.
From is intended to 1 rotates toward the theta _2, the coordinates of the cam 13 corresponding to an arbitrary angle theta in the range of theta ₂ from the rocking angle range theta ₁ and G, and the line segment OG = L, The mathematical formula shown in Formula 1 below is established.

[0018]

[Equation 1] Therefore, the movement width (L ₂ −L ₁ ) of the cam 13 for satisfying the required swing angle width (θ ₂ −θ ₁ ) is represented by the following mathematical formula 2.

[0019]

[Equation 2] Further, since the movement width (L ₂ −L ₁ ) of the cam 13 is also the movement width of the rack 10, assuming that the pitch circle diameter of the pinion 9 driven by the rack 10 is φD, the following mathematical formula 3 is given. Represented.

[0020]

(Equation 3) Therefore, from the equations (2) and (3), the following equation 4 is established.

[0021]

[Equation 4] Therefore, the following formula 5 is obtained from the formula (1).

[0022]

(Equation 5) Therefore, the locus of L, which is a function of θ, becomes the shape of the cam 13. The phase of the swinging angle width of the polishing plate 1 determined by the cam 13 can be changed by moving the shaft center of the cam 13, or by arranging the cams 13 of a required phase in multiple stages. It can be changed easily.

As described above, in this embodiment, P × V × ΔT =
In order to obtain a constant operation, the dwell time ΔT is changed by the rocking device, but the present invention is not limited to this, and the pressing force P of the spring or the like is changed by the cam 13 of the same shape. The same effect can be obtained by changing it, or the peripheral speed V of the polishing plate 1 can be controlled as required.

Next, the invention of the holder portion 18 in the lens polishing apparatus a will be described. As shown in FIG. 9, a small hole 22 is dug in the shaft 20 of the rotary member 19 to reach the neck portion of the flange 21. The air that is communicated with the small hole 22 from the peripheral surface of the neck portion to the discharge hole 23 that is provided in a cross shape and is guided to the ventilation hole 25 that penetrates the shaft center of the holder 24 is the rotating body 1.
Discharge from the discharge hole 23 through the small hole 22 of the holder 9
An air jet flow region 26 is formed between the front end face of No. 4 and the flange 21 of the rotating body 19. This jet basin 26
As a result, wear dust during polishing will not enter the rotary bearing, and smooth rotation will be maintained.
The polishing accuracy is remarkably improved.

Further, the holder portion 18 in the present invention is one in which the weight of the holder 24 is erased and only the pure pressing force P is applied to the lens 17, and the structure thereof is shown in FIGS. 8 and 9. That is, the projecting piece 27 protruding to the upper end of the holder 24 is guided by the guide groove 30 which is vertically provided so as to penetrate through the guide plate 29 integrated with the support body 28 of the holder 24, and the screw shaft 31 is screwed to the projecting end portion. It is fixed,
One end of a spring 32 is engaged with the upper end of a part of the screw shaft 31, and the other end is moved up and down in the guide groove 30 to fix the screw 3.
3 is engaged with an adjusting body 34 fixed at an appropriate position, one end of a plurality of (three) springs 35 is engaged with the lower end of the screw shaft 31, and the other end is similar to the above. Regulator 3
It is made by fastening to 6.

The pressing force adjusting mechanism b having the above structure is
When the upper adjusting body 34 is pulled up while the lower adjusting body 36 is loosened with respect to the guide groove 30, the holder 24 is pulled up through the spring 32, but the upper adjusting body 34 is pulled up in a slightly floating state. The body 34 is fixed to the guide plate 29. In this state, pulling down the lower adjustment body 36 causes the spring 35
The holder 24 is pressed by a predetermined pressing force in the state where the weight is not applied, and the lower adjusting body 36 is fixed to the guide plate 29 at a position where the set pressing force P is generated. In this way, in the state where the own weight of the holder 24 is erased, the spring 35 having a predetermined spring constant is converted into a load corresponding to the deflection and a pure pressing force is applied to the holder 24.
Therefore, a surely grasped pressing force acts on the lens 17 held by the rotating body 19 rotatably supported by the holder 24.

[0027]

As described above, according to the present invention, in the polishing process of the lens, since the driven rotation of the lens is smoothed by applying an accurate pressing force, the polishing accuracy is remarkably improved. Moreover, since the polishing work acting on the lens can be kept constant, there is an effect that a lens having a stable radius of curvature can be processed for a long period of time.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a main part of a lens polishing apparatus a of the present invention.

FIG. 2 is a schematic right side view of a main part in FIG.

FIG. 3 is an explanatory view of the principle of the polishing method to which the present invention belongs.

FIG. 4 is a characteristic curve diagram showing a change rate ΔV of the peripheral velocity V and a calculated change rate Δ ² T of the residence time ΔT.

FIG. 5 is an explanatory diagram of a contour of a cam.

FIG. 6 is a schematic vertical sectional view of a main part in a conventional Oscar system.

FIG. 7 is a schematic vertical sectional view of a main part in a conventional ball-core polishing method.

FIG. 8 is a side view of a holder portion in the lens polishing apparatus a.

9 is an enlarged vertical cross-sectional view of the main part of FIG.

[Explanation of symbols]

 1 Polishing Plate 2 Swing Arm 4 Housing 5 Spindle 6 Swing Shaft 8 Housing 9 Pinion 10 Rack 11 Slide Unit 12 Cam Follower 13 Cam 15 Bearing Unit 16 Pedestal 17 Worked Lens 18 Holder 19 Rotating Body 20 Shaft 21 Flange 22 Small Hole 23 Discharge hole 24 Holder 25 Vent hole 26 Jet flow field 27 Projecting piece 28 Supporting body 29 Guide plate 30 Guide groove 31 Screw shaft 32 Spring 33 Fixing screw 34 Adjusting body 35 Spring 36 Adjusting body P Pressing force V Circumferential speed ΔT Residence time L cam Trajectory a Lens polishing device b Pressing force adjustment mechanism.

Claims (5)

[Claims] 1. A spherical core polishing method in which a polishing surface of a lens to be processed is brought into contact with and pressed against a rotating polishing tool, and the polishing tool is oscillated with the center of a radius of curvature as a swing center. , P is a pressing force applied per unit surface area of the polishing surface of the lens to be processed, V is a peripheral speed of the polishing tool at a position where the polishing surface of the lens to be processed and the polishing tool are in contact, V of the lens to be processed is When the relative residence time of the lens to be processed, which changes due to the swing at the position where the polishing surface and the polishing tool are in contact with each other, is ΔT, the polishing tool is swung with P × V × ΔT = constant. Polishing method for the lens. 2. A polishing tool is pivotally supported by a swing shaft at the center of the radius of curvature of the lens to be processed, the lens to be processed is attached to a subordinate rotary body, and a holder for axially supporting the rotary body is pushed to a predetermined position. A spherical core polishing apparatus which is pressed and supported by pressure, wherein the swing shaft is swung by a swing mechanism having P × V × ΔT = constant according to claim 1. 3. A swing mechanism comprising: a pinion pivotally supported by a swing shaft; a rack that meshes with the pinion; a cam that gives the rack a predetermined reciprocating rectilinear motion; and a drive unit that drives the cam. The lens polishing apparatus according to claim 2, which comprises: 4. The lens polishing apparatus according to claim 2, wherein an air jet flow region is formed between the front end surface of the holder that axially supports the rotating body and the rotating body. 5. The method according to claim 2, wherein the supporting system is made to bear the self-weight of the holder including the rotating body, and the self-weight is eliminated to apply a pure pressing force to the lens to be processed. Alternatively, the lens polishing apparatus according to claim 4.