JPH1148116A - Working method for spherical form such as lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously machine stably a spherical surface such as a lens into a spherical surface of fixed curvature radius from an initial stage of production starting by keeping form accuracy of a former tool. SOLUTION: A ΔH (dimension) of each process is set so that a set value (ΔHy) of ΔH in a preceding process relating to a set value (ΔHx) of ΔH in own process is set to get small by a numeric value which is total value of one half of allowable tolerance width (±a) of ΔH in own process, one half of allowable tolerance width (±b) of ΔH in the preceding process and 0-1 μm, taking tolerance relating to a target ΔH (dimension) in an actual working into account. Difference ΔH between a spherical form 2 (ΔHy, that is, curvature radius Ry) such as a spherical lens and a formed tool 1 (ΔHx, that is, curvature radius Rx) is thereby reduced to required minimum to attain a proper contacting condition in an initial stage working, and thereby a worked lens is continuously worked stably without generating uneven abrasion of the formed tool.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for processing a spherical shape such as a spherical lens used for a camera or a video camera.

[0002]

2. Description of the Related Art Conventionally, in processing a spherical shape such as a spherical lens used for a camera or a video camera, a material such as an optical glass formed by press molding is subjected to several processes such as rough grinding, fine grinding and polishing. By performing the process, the surface roughness of the spherical shape is gradually improved and processed into a desired spherical shape. As shown in FIG. 2, the allowance for each step is a polishing allowance 111 for the polished (completed) surface 101 and a fine allowance (or sanding) allowance 11 for the polished (completed) surface 101.
2 and rough grinding allowance 113, polishing (completion) surface 1
The sum of these allowances and 01 is set to be the thickness and radius of curvature of the pressed material.
That is, when a predetermined specification of a lens having a radius of curvature of R ₀ is presented in advance, in the fine grinding step which is a step before the polishing step which is the final step, the polishing is performed to a polished surface radius of curvature (R ₀ ). The radius of curvature of the finely ground surface (R ₁ ) with the addition of the allowance 111 (ΔR ₀ ) and the same center of curvature o is defined as the radius of curvature of the finely ground surface (R ₁ ). (R ₁ ) fine grinding allowance 112
([Delta] R ₁₎ to the added and the same center of curvature o a with those rough grinding surface radius of curvature (R _{2), i.e., R 1 = R 0 + ΔR} 0 R 2 = R 1 + ΔR 1 R 3 = R 2 + ΔR ₂ = R ₀ + ΔR ₀ + ΔR ₁ + ΔR ₂ The curvature dimension of each step is set by adding the allowance for the surface defect layer in each step to the predetermined curvature dimension (R ₀ ) presented in advance. Each step is processed based on the set curvature dimension of each step.

[0003] When setting the steps of the spherical shape of these lenses and the like, a simple ring-type curvature meter is used to manage the shape and curvature in each step, and a spherical prototype having a reference radius of curvature is used. The curvature radius accuracy is managed by comparative measurement with a spherical shape of a lens or the like to be compared.

As shown in FIG. 4, this kind of ring-type simple curvature meter 150 has a cylindrical measuring ring 151 having an open portion 151a at one end and a dial gauge 152 attached to the measuring ring 151, and has an axial direction. A movable measuring element 153 is provided, and when measuring the spherical shape of a lens as an object to be measured having, for example, a concave spherical surface using the ring-type simple curvature meter 150, first, FIG. As shown in the figure, the outer peripheral edge of the ring opening 151a of the ring-type simple curvature meter 150 and the tracing stylus 153 are pressed against the spherical prototype Wo, which is the master gauge, to adjust the scale of the dial gauge 152 to zero point. Then, as shown in FIG. 4B, the simple curvature meter 150 that has been subjected to the zero-point adjustment is pressed against the lens W as the object to be measured instead of the spherical prototype Wo,
The scale of the dial gauge 152 is read. By measuring as described above, the difference ΔH (= H−H) between the height Ho from the vertex of the spherical surface of the spherical prototype Wo to the chord and the height H from the vertex of the spherical surface of the lens W to be measured to the chord is obtained. Ho) can be read from the scale of the dial gauge 152.
Then, the difference ΔH (= H−Ho) between the height from the vertex of the spherical surface to the chord and the spherical prototype Wo.
(Hereinafter, this difference is simply referred to as ΔH.)
As shown in the above, the difference ΔR (= R−Ro) between the radius of curvature R of the spherical shape and the radius of curvature Ro of the spherical prototype can be converted by the following equation (1).

H = R− {R ² − (d / 2) ² } ^0.5 ΔH = ΔR {(1−cos θ) / cos θ} (1) where Ro: radius of curvature of spherical prototype Wo R: The radius of curvature d of the measurement lens W: the diameter of the measurement ring θ: sin ^-1 (d / 2Ro) In the above-described conventional process setting method for processing a spherical shape, for example, in the polishing process shown in FIG. The lens 202 having a radius of curvature R ₁ processed by the precision grinding process, which is a pre-process of the polishing process, has a target radius of curvature R ₀ in the polishing process, which is its own process, and has a processed lens having a concave-convex inversion. Polishing is performed by pressing the mold tool 201, and the difference in curvature radius ΔR (ΔR ₀ = R ₁ −R ₀ ) is used as a polishing allowance. 3 (a) in FIG.
As shown in the figure, a lens 202 to be machined having a radius of curvature R ₁ in the previous process and a forming tool 201 having a target radius of curvature R ₀
The difference ΔR _{0 in the} curvature dimension, that is, the difference ΔH in the process, is large, so that the initial contact between the lens 202 to be processed and the forming tool 201 at the initial stage of the processing is extremely strong, and in some cases, the contact between the lens and the die 201 in FIG. As shown in (b) and (c), the outer peripheral portion of the forming tool 201 has an initial radius of curvature (R) due to uneven wear.
_{Since the} curvature radius (R _i ) different from that of ( ₀ ) is formed, the shape accuracy cannot be maintained, and as a result, it is difficult to stably produce a lens to be processed for processing and transferring the curvature shape of the forming tool.
For this reason, there are cases where a skilled worker corrects the setting of the allowances ΔR and ΔH based on experience and intuition while actually processing the lens, and adjusts the uneven wear of the die tool.
The settings were inconsistent and did not lead to stable production.

In particular, in a lens to be processed having a large half-opening angle θ (θ = sin ⁻¹ (d / 2r)) represented by the effective radius of curvature (d) with respect to the radius of curvature (r) of the lens, In order to emphasize the removal efficiency of the lens to be processed, the ΔH difference in each process was often set to be large, so that the degree of contact between the lens to be processed and the tool was strong, and the tool was unevenly worn. Could not maintain the shape accuracy.

[0007]

As described above, it is extremely difficult to continuously produce a lens having a constant radius of curvature in the processing and production of a spherical lens.
In particular, uneven wear of the mold tool occurs due to the ΔH difference between each step from the pressing material grinding to the final polishing step, and
A change in the radius of curvature of the lens to be processed becomes a problem due to a change in the curvature dimension of the forming tool. Therefore, in order to maintain the curvature and dimensions of the forming tool, setting ΔH in each step is an important matter. However, in the prior art, the radius of curvature of the processed spherical surface which has been processed during the manufacture of the spherical lens is measured, and a change value of the radius of curvature is obtained by comparing with the measured value of the previously processed spherical surface. Alternatively, a method of modifying the setting of ΔH in the preceding process, or a method of adjusting the value based on the experience and intuition of a skilled person, and the like are customary. In order to set ΔH in this way, the degree of ΔH difference in each process for maintaining the shape accuracy of the forming tool should be determined. There were challenges.

(1) For a forming tool whose shape has exceeded the allowable range due to wear, it must be corrected by a master tool having the same radius of curvature as the workpiece material. It is necessary to modify the master tool because the master tool itself wears by repeating,
This is a factor in reducing productivity. In addition, these correction operations cannot be easily performed unless the technician has a certain level of skill.

(2) When the change of ΔH due to tool wear is remarkable, the setting of ΔH in the previous process or the own process is changed. In this case, even if the setting of ΔH in one process is changed, the change in ΔH in the preceding and following processes is performed. In order to influence the tendency of the change, it is necessary to review the ΔH setting throughout the entire process.
As a result, the tool must be remanufactured, resulting in a large loss in production start-up.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and maintains the shape accuracy of a forming tool so that a spherical lens can be stably produced from the beginning of production. It is an object of the present invention to provide a method of processing a spherical shape such as a lens capable of continuously processing a spherical shape having a constant radius of curvature.

[0011]

Means for Solving the Problems The present inventor has conducted intensive studies on continuous and stable machining in the machining of a spherical shape such as a spherical lens, and has conducted various experiments. As a result, the radius of curvature of the lens to be machined is determined. The difference between the rate of change (the amount of change in the radius of curvature per lens to be processed) and the set value of ΔH (ΔHx) targeted in the own process and the set value of ΔH (ΔHy) in the previous process, ΔH difference (= ΔHx−) between the set value of ΔH in the previous process and the set value of ΔH in the process
ΔHy) and the following (1) to (3) have been found, and the present invention has been completed.

(1) The smaller the difference ΔH in the previous process from the process, the more stable the ΔHx of the process.

(2) When the difference ΔH in the previous step with respect to the own step is (+), ΔHx in the own step is not stable. Causes a variation in curvature.

(3) The ΔH difference between the self-process and the preceding process is zero.
The case of −１-1 μm is most effective in the stable processing of ΔHx in the own process.

That is, in the method of processing a spherical shape according to the present invention, a plurality of processing steps are performed to gradually improve the surface roughness of a material to be processed and finish the spherical shape. The setting of the radius of curvature of the spherical surface in the process is managed by the difference ΔH from the spherical base plate as the master for the height from the vertex to the chord of the spherical surface by the simple curvature meter, and the value of the previous process with respect to the set value of ΔH in the own process is managed. The set value of ΔH is set to the sum of の of the allowable tolerance width of ΔH of the own process and の of the allowable tolerance width of ΔH of the previous process.
It is characterized in that it is set to be smaller by a value obtained by adding を 1 μm.

Further, the method for processing a spherical shape according to the present invention is suitable for processing an optical lens, and further, optical glass is suitable as a material of a material to be processed.

[0017]

[Working] Spherical processing to finish the spherical shape by gradually improving the surface roughness of the material to be processed by applying a plurality of processing steps to the material to be processed such as a spherical lens used in cameras and video cameras. In the method, the setting of the radius of curvature of the spherical surface in each processing step is managed by the difference ΔH from the master spherical surface standard with respect to the height from the vertex to the chord of the spherical surface using a simple curvature meter, and the target ΔH ( Considering the tolerance to the dimension, the set value (Δ
The set value (ΔHy) of ΔH in the previous process with respect to Hx) is set to １ ／ of the allowable tolerance width (± a) of ΔH of the own process.
And 1 of the allowable tolerance width (± b) of ΔH in the previous process.
/ Hy = ΔHx − ｛(a + b) + (0
1) By setting ΔH in each process based on｝, the difference ΔH between the spherical shape of a spherical lens or the like (= ΔHy in the previous process) and the mold tool (= ΔHx in the own process) is minimized. When the initial contact state is appropriate, the lens to be processed can be continuously and stably processed without causing uneven wear of the forming tool.

[0018]

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

FIG. 1 is a schematic view for explaining the machining method of the present invention, and uses a forming tool 1 provided with a spherical surface having a target set radius of curvature Rx in its own process to set a set curvature in a previous process. A mode of processing a lens 2 as a workpiece having a spherical surface with a radius Ry is illustrated.

The inventor of the present invention has conducted intensive studies on continuous and stable machining in the machining of a spherical shape such as a spherical lens used in a camera or a video camera, and has conducted various experiments. Rate of change of radius of curvature of lens (change of radius of curvature per lens to be processed)
Is ΔH which is the target of grinding or polishing in its own process.
Set value (ΔHx) and the set value of ΔH in the previous process (ΔHx)
Hy), that is, ΔH of the preceding process with respect to the own process.
It was found that the difference (= ΔHx−ΔHy) had the following correlation.

(1) The smaller the difference ΔH in the previous process from the process, the more stable the ΔHx of the process.

(2) When the difference ΔH in the previous step with respect to the own step is (+), ΔHx in the own step is not stable. Causes a variation in curvature.

(3) The difference ΔH in the preceding process from the own process is 0
The case of −１-1 μm is most effective in the stable processing of ΔHx in the own process.

From the above, the ΔH difference in the preceding process with respect to the own process is preferably (0) or (−). Further, since the ΔH setting in each process is provided with a manufacturing tolerance, for example, , ΔA tolerance of the own process ± a, ΔH of the previous process
When the tolerance is ± b, the ΔH setting is preferably ΔHy = ΔHx− (a + b) in order to maintain the above relationship, and the smaller the ΔH difference in the preceding process with respect to the own process, the more particularly the range from 0 to −1 μm Is effective for stable processing of ΔHx in its own process. Therefore, the target Δ in actual machining
Considering the tolerance for H (dimension), the set value of ΔH in the previous process (ΔHy) with respect to the set value of ΔH in the own process (ΔHx)
To the allowable tolerance width (± a) of ΔH in the process.
/ 2 and the allowable tolerance width of ΔH in the previous process (± b)
Is preferably set to be smaller by a value obtained by adding 0 to 1 μm to the sum of １ ／, that is, this relationship can be expressed by the following equation (2).

ΔHy = ΔHx − {(a + b) + (0 to 1)} (2) Then, the radius of curvature (Ry) corresponding to ΔHy in the previous process, which is obtained by Expression (2), is shown in FIG. As shown, the center allowance is set so as to satisfy the necessary allowance (ΔRx) in the own process.

By setting and working as described above, the difference ΔH between the lens 2 (= ΔHy in the previous process) and the forming tool 1 (= ΔHx in the own process) in the working can be minimized. In addition, by making the contact condition in the initial stage of processing appropriate, stable production of the lens 2 to be processed becomes possible without causing uneven wear of the forming tool 1.

By setting ΔH in each step as described above, it is possible to secure a worn state of the tool that does not cause a change in ΔH, and to realize stable machining of the lens.

On the other hand, in the conventional method of setting ΔH, as shown in FIG. 3 and described above, the ΔH difference between the steps often increases in order to emphasize the removal efficiency of the lens to be processed. The contact condition at the beginning of processing is a strong edge contact,
In some cases, stable production of the lens to be processed was difficult due to uneven wear of the mold tool.

[0029]

【Example】

(First embodiment) Next, ΔH based on the processing method of the present invention
The comparison between the setting and the ΔH setting in the related art will be described with reference to an example of a shape stability result in actual processing of a lens having a lens half-open angle of 40 °.

The general processing steps from the pressing of the lens made of optical glass or the like to the final curvature shape include the rough grinding, first fine grinding, second fine grinding, and polishing of the pressed material. The general outline of each step will be described below.

(1) In a rough grinding step (hereinafter, also referred to as a CG step), as shown in FIGS. 5A and 5B, a spherical diamond wheel 11 is generally rotated to form a spherical surface. Refers to curve generator processing to create grinding.

In the processing by the curve generator, the cup-shaped diamond grinding stone 11 is pressed against the lens 12 to be processed held by the lens holder 15 at an inclination angle θ. That is, when the diameter of the grindstone 11 is D, the radius of the roundness of the grinding end of the grindstone 11 is p, and the radius of curvature of the spherical surface is R, the positional relationship is sin θ = D / 2 (R ± p). set.

Then, the cup-shaped diamond grindstone 11 having an abrasive grain size of about # 150 to # 320 is rotated at a grinding wheel shaft rotation speed of about 4000 to 15000 rpm, and the lens shaft 13 holding the lens 12 to be processed is rotated at a rotation speed of 1 to 30 r.
The lens to be processed 1 is fed while rotating at about pm to a predetermined lens thickness in the lens axis direction.
2 is processed into a spherical shape. The surface roughness of the lens to be processed is
Rmax is targeted at about 6 to 10 μm.

FIGS. 5A and 5B show a convex lens 12a and a concave lens 12a by a curve generator.
It is the schematic which illustrates the aspect which processes each b.

(2) The first step of fine grinding (hereinafter also referred to as SM1 step) is, as shown in FIG. 6 and FIG. The processing target lens 22 held by the lens holder 25 is pressed against the forming tool 21 of about # 1200 via the lens receiving member 27 at a processing pressure of ² to 5 kg / cm ² , and the forming tool 21 is rotated at 200 to 1500 rpm. Then, relative motion is given to the mold tool 21 and the lens 22 to be machined,
In addition, this is a spherical-shaped processing step of processing the workpiece lens 22 by giving the shaping tool 21 or the workpiece lens 22 a swinging motion of about 60 times / minute in a tangential direction of the tool spherical surface. The target roughness is about Rmax2 to 5 μm.

FIG. 6 (a) shows an SM for convex lens processing.
FIG. 6B is a schematic view illustrating a processing mode in which the tool axis 24 tilted at an angle θ with respect to the lens axis 23 is swung at a swing angle θa in one step, and FIG. FIG. 7 is a schematic diagram illustrating a processing mode of swinging a tool axis 24 inclined at an angle θ with respect to a lens axis 23 at a swing angle θa in an SM1 step, and FIG. Axis 24 is lens axis 2
3 and the lens 22 to be processed
Holder 2 for holding the lens through lens receiving member 27
FIG. 11 is a schematic diagram illustrating a processing mode of a type in which a kansetsu 28 that pivotally supports the wing 7 is pivoted at a pivot angle θa.

(3) The fine grinding second step (hereinafter also referred to as SM2 step) is performed to obtain a finer surface roughness than the SM1 step. It is set to about 1500 to # 3000, and other conditions are in accordance with the SM1 process. The target surface roughness of the lens to be processed is Rmax of about 0.2 to 1 μm.

(4) As shown in FIGS. 8A and 8B, the polishing step (hereinafter also referred to as the PP step) is performed by the forming tool 31 having a curvature radius R in which the concave and convex of the processed lens is inverted. Lens holder 35 via lens receiver 37
Of the lens 32 to be processed held at a processing pressure of 2 to 5 kg / c.
pressing in m ^2, 200~1500rp the total mold tool 31
m to impart relative motion to the forming tool 31 and the lens 32 to be machined, and
Is a spherical machining step of machining the lens 32 by giving a swinging motion of about 60 times / minute in the tangential direction of the tool spherical surface, and the surface roughness of the lens is Rmax
The target is about 0.01 μm or less. The contact surface of the mold tool 31 with the lens 32 to be processed is a polyurethane sheet 31b having a thickness of about 0.3 to 1 mm, and the radius of curvature in consideration of the thickness of the polyurethane sheet 31b from the radius of curvature which is the final target of the lens to be processed. Is adhered to the tool holder plate 31a.

FIG. 8A shows a convex lens processed PP.
In the process, the tool shaft 34 is pivoted with respect to the lens
FIG. 8 is a schematic view illustrating a machining mode in which the tool shaft 34 is tilted at a swing angle θa and the tool shaft 34 is swung at a swing angle θa.
(B) is a PP process of concave lens processing, in which the tool axis 34 is inclined with respect to the lens axis 33 at the pivot center angle θ, and the screw 38 that pivotally supports the lens holder 37 that holds the lens 32 to be processed is pivoted. It is the schematic which illustrates the working mode of the form which rock | fluctuation by angle (theta) a.

Next, a procedure for setting ΔH in each step in consideration of the tolerance of ΔH in each step with respect to the ΔH set value in the polishing step that results in the final curvature shape of the lens will be described. Note that the general ΔH tolerance of each step is as shown in Table 1 below.

[0041]

[Table 1] Therefore, when the ΔH set value in the polishing step that results in the final curvature shape of the lens having a lens half-open angle of 40 ° is −0.66 μm, the ΔH set value in the second fine grinding step is given by ΔH = −0.66-{(0.33 + 0.5) + (0-1)} = − 1.5 (〜−2.5) The ΔH set value in the first step of the fine grinding is similarly calculated using the above-described equation ( From 2), ΔH = (− 1.5 to −2.5) − {(0.5 + 0.5) + (0 to 1)} = − 2.5 (to −4.5) Is set to ΔH = (− 2.5 to −4.5) − {(0.5 + 1.0) + (0 to 1)} = − 4.0. (~ -7.0) From the above calculations, the setting of ΔH in each step according to the present invention is as shown in Table 2. (In the column of ΔH set value in Table 2, the upper row shows the value under the condition that each process set width is 0, and the lower row shows the value under the condition that each process set width is 1 μm.)

[0042]

[Table 2] On the other hand, the setting of ΔH by the conventional setting method is shown in Table 3
become that way. (Note that, in the column of the ΔH set value in Table 3, the lower row shows the value of a modification example in actual machining.)

[0043]

[Table 3] Based on these settings, the processing stability of the lens to be processed in actual processing was compared. FIG. 9 shows the result of continuous machining using the rough grinding to fine grinding first (CG to SM1) process having a large ΔH difference between the previous process and the own process as an example. ΔH in the pre-process of each setting uses a lens processed to the setting ΔH in the coarse grinding process, and the fine grinding first process, which is its own process,
ΔH of the lens to be processed in the initial processing is set to ΔH
Finish the shape of the forming tool so that
00 pieces were continuously processed.

As a result, in the conventional setting method having the largest ΔH difference, the number of continuous machining within ± 0.5 μm which is the ΔH tolerance standard in the first step of fine grinding was 20 or less. With the setting width 0 of the setting of the present invention having the smallest ΔH difference, stable processing within the ΔH tolerance standard was possible even at the end of processing 300 pieces. In addition, even in the setting width of 1 μm according to the present invention, about 200 continuous stable machining could be performed within the ΔH tolerance standard.

Next, Table 4 shows the allowance for centering the lens in the setting of the present invention. (In the column of the lens centering allowance in Table 4, the upper row shows the value under the condition that each process setting width is 0, and the lower row shows the value under the condition that each process setting width is 1 μm.)

[0046]

[Table 4] As shown in the allowance margin in Table 4, each process setting width was 1
By setting μm, the allowance can be reduced by about 1.5 μm. This can be said to be effective in shortening the processing time in the fine grinding second step and the polishing step having a small removal ability. As described above, by setting each process setting width to 1 μm or less, the superiority of continuous stable processing is secured over the conventional setting method, and productivity is improved even when each process setting width is set to 0. Can be achieved.

(Second Embodiment) FIG. 10 is a table showing the ΔH setting based on the present invention and the ΔH setting based on the prior art for each step of a commonly used lens having a half-open angle of 10 ° to 60 °. It is. In the ΔH setting based on the prior art, the ΔH difference in each step increases as the lens half-opening angle increases, whereas in the ΔH setting according to the present invention, the ΔH difference in each step hardly changes. I understand.

Next, the effect of the ΔH difference in each step on the processing stability will be described below. Table 5 shows the lens half-open angle 2
This is a comparison between the ΔH setting based on the present invention and the ΔH setting based on the prior art at 0 °.

[0049]

[Table 5] Rough grinding to fine grinding first (CG to S based on ΔH setting in Table 5)
FIG. 11 shows a comparison of the processing stability of the lens to be processed in the actual processing in the M1) step. 200 pieces were continuously processed in the same manner as in the first embodiment. In contrast to the ΔH tolerance standard of ± 0.5 μm in the first step of the fine grinding, the continuous processing was 120 in the setting according to the conventional technique, whereas the setting in the present invention enabled stable processing even at the end of processing 200 pieces. .

Table 6 shows a comparison between the ΔH setting based on the present invention and the ΔH setting based on the prior art when the lens half angle is 60 °.

[0051]

[Table 6] Fine grinding first to fine grinding second (SM based on ΔH setting in Table 6)
FIG. 12 shows a comparison of the processing stability of the lens to be processed in the actual processing in steps 1 to 2). 200 pieces were continuously processed in the same manner as in the first embodiment. In contrast to the ΔH tolerance standard of ± 0.5 μm in the first step of the fine grinding, the number of continuous machining in the conventional setting was 20, whereas in the setting of the present invention, stable machining was possible even at the end of the machining of 200.

As described above, the setting of ΔH according to the present invention can be applied to various lens shapes such as lenses having different lens half-open angles and various processes, and enables continuous stable processing of spherical shapes such as spherical lenses. It is effective for

[0053]

As described above, the method for processing a spherical shape such as a spherical lens according to the present invention can suppress uneven wear of a mold tool in continuous processing, and reduce the stability of ΔH of a lens to be processed. And productivity can be improved.

Further, it is not necessary to frequently correct the shape of the forming tool as in the prior art, so that it is possible to save labor and to greatly reduce the manufacturing cost of the lens.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a ΔH difference between a self-process and a preceding process by process setting based on a processing method of the present invention.

FIG. 2 is a conceptual diagram for explaining a process setting and a necessary allowance for each processing step in the conventional processing of a spherical shape.

FIG. 3 is a schematic diagram showing a contact state and a change in shape of a forming tool and a lens to be processed in an initial stage of processing by setting a process in processing of a conventional spherical shape.

FIG. 4 is an explanatory diagram for explaining ΔH and a relationship between ΔH and a radius of curvature by a simple curvature meter used for setting a process of processing a spherical shape.

FIGS. 5A and 5B are schematic diagrams illustrating a manner in which a convex lens and a concave lens are processed by a curve generator, respectively.

FIGS. 6 (a) and (b) are schematic views illustrating a processing mode of a fine grinding step of finely grinding a convex lens and a concave lens, respectively.

FIG. 7 is a schematic view illustrating a processing mode of a fine grinding step for finely grinding a concave lens.

FIGS. 8 (a) and (b) are schematic views illustrating a processing mode of a polishing step of polishing a convex lens and a concave lens, respectively.

FIG. 9 shows a pre-process (CG process) and a self-process (S process) with respect to ΔH set based on the present invention and the prior art.
5 is a table for comparing processing stability due to a difference in ΔH difference in the M1 step).

FIG. 10 is a table for comparing ΔH of each step set according to the lens half-open angle based on the present invention and the prior art.

FIG. 11 is a table comparing processing stability in the CG step to the SM1 step with respect to ΔH set when the lens half-open angle is set to 20 ° based on the present invention and the prior art.

FIG. 12 is a table comparing machining stability in the SM1 process and the SM2 process with respect to ΔH set when the lens half-open angle is set to 60 ° based on the present invention and the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold tool 2 Lens (workpiece) 11 Cup-shaped diamond grindstone 12 Workpiece lens 13 Lens axis 14 Grindstone axis 15 Lens holder 21, 31 Mold tool 22, 32 Workpiece lens 23, 33 Lens axis 24, 34 Tool Shaft 25, 35 Lens holder 26, 36 Oscillation center 28, 38 Kansashi 31a Polyurethane sheet 31b Mold tool plate 100 Lens 101 Polished surface 102 Fine ground surface 103 Rough ground surface 104 Press surface 111 Polishing allowance 112 Fine grinding allowance 113 Rough grinding allowance 150 Simple curvature meter 151 Measuring ring 152 Dial gauge 153 Measuring element

Claims (3)

[Claims] 1. A method of processing a spherical shape, in which a plurality of processing steps are performed to gradually improve the surface roughness of a material to be processed to finish a spherical shape, wherein a radius of curvature of a spherical surface in each processing step is set. The height from the vertex to the chord of the spherical surface by the simple curvature meter is managed by the difference ΔH from the master spherical prototype, and the set value of ΔH in the previous process with respect to the set value of ΔH in the own process is stored in the own process. 1/2 of the allowable tolerance width of ΔH and Δ of the previous process
A method of processing a spherical shape, characterized in that the value is set to be smaller by a value obtained by adding 0 to 1 μm to a sum of 許 容 of an allowable tolerance width of H. 2. The method according to claim 1, wherein the material to be processed is an optical lens. 3. The method for processing a spherical shape according to claim 1, wherein the material to be processed is optical glass.