JPH10309601A - Manufacture of saw blade shape optical element forming die and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make form accuracy of a saw blade shape groove of a saw blade optical element forming die be extremely good. SOLUTION: In manufacture of a saw blade shape optical element forming die which is cut to the specified depth, putting a cutting edge ridge line 2d of a cutting bite 2 on a base material 1 of the saw blade shape optical element forming die, cutting edge angle θ of a cutting edge 2b which is changed by deflection of the cutting bite 2 during cutting is compensated in reverse direction of change by the deflection, and, by the same amount with a change amount Δθby the deflection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for manufacturing a saw-shaped optical element mold for processing a mold for an optical element having a fine shape such as a Fresnel lens or a grating lens with high precision.

[0002]

2. Description of the Related Art Conventionally, as a method for processing a mold for an optical element having a fine shape such as a Fresnel lens or a grating lens, a method shown in FIG. 12 is generally performed. That is, as shown in FIG. 12A, a cutting tool b is applied to a mold material a of a Fresnel lens molding die, and then, as shown in FIG. By removing b, as shown in FIG. 12C, cut surfaces c and d corresponding to the vertical surface and the inclined surface of the Fresnel lens mold are formed. Then, the cutting angle of the cutting bit b is changed in accordance with the change in the slope angle of the Fresnel lens mold.

However, in this cutting method,
Of the cutting surfaces c and d formed on the mold material a, the cutting surface d corresponding to the slope is transferred with the shape of the cutting edge of the cutting tool b,
Although the surface is finished smoothly, a cutting edge c of the cutting bit b which has been cut remains on the cutting surface c corresponding to the vertical surface. When a Fresnel lens is formed using a Fresnel lens mold having a cutting edge, cutting marks are transferred to the lens surface of the formed Fresnel lens. When this Fresnel lens is used, light is irregularly reflected by a cutting mark, and a line for each pitch of the Fresnel lens appears white. Further, when the molded resin-made Fresnel lens is released from the Fresnel lens mold, the resistance is so large that the Fresnel lens is not completely released from the Fresnel lens mold, which may damage the lens surface. . The same applies to not only the Fresnel lens but also an optical element having a finer shape such as a grating lens.

Therefore, as a solution to such a problem,
For example, a technique disclosed in Japanese Patent Publication No. 61-25481 is disclosed. This technique will be described with reference to FIG. In FIG. 13, a mold material 110 of a Fresnel lens molding die is fixed to a work table such as a lathe. FIG. 13 (A)
As shown in FIG.
11 are brought into contact with each other, and as shown in FIG.
Cut about 4 mm. At this time, one of the cutting edges 112a of the blade 112 abuts on the slope 114a of the cutting surface, and finishes the slope 114a.

After the cutting bit 111 is cut to a predetermined cutting depth, the cutting bit 111 is swung about the cutting edge of the cutting tool 112 so that the other cutting edge 11 of the cutting tool 112 is cut.
2b is a vertical surface 114 of the cutting surface as shown in FIG.
b, and the cutting surface 114b is finished in this contact state. After finishing the vertical surface 114b and the inclined surface 114a of the cutting surface, as shown in FIG.
The cutting tool 111 is removed from the cutting surface, and preparations are made for processing the next cutting surface. In this way, a cutting surface having a sawtooth cross section is sequentially formed on the surface of the mold material 110,
A Fresnel lens mold is manufactured.

Here, the geometrical characteristics of the Fresnel lens will be described. The Fresnel lens has a large number of concentric grooves, and each groove has a sawtooth-shaped cross section in the optical axis direction, and each sawtooth-shaped groove forms a right triangle. The width of each groove in the radial direction, that is, the pitch, is wider toward the optical axis and narrower toward the outer edge. The depth of the groove is constant. The slope of each groove depends on the pitch and depth of the groove. With respect to a plane perpendicular to the optical axis, the slope of the groove with a wider pitch is gentler, and the slope of the groove with a smaller pitch is steeper. ing.

[0007]

However, the prior art disclosed in Japanese Patent Publication No. 61-25481 has the following problems. In this conventional cutting method, after machining either the inclined surface or the vertical surface of the cutting surface, the cutting tool is rotated around the cutting edge,
By processing the cutting edge in contact with the entire surface on the other side,
This is to finish the cut surface smoothly without leaving any cutting marks on the cut surface of the Fresnel lens mold. However, in the method of performing the processing while controlling the cutting bit angle, since the rigidity of the cutting bit supporting portion is relatively low, the vertical drag on the slope formed in the mold material causes
Elastic deformation occurs in the cutting tool support and the cutting tool itself,
The slope cannot be formed at an exact angle.

[0008] Further, as the pitch width is wider, the slope is longer, so that the vertical reaction force applied to the cutting tool increases, and the bending of the cutting tool increases. When the cutting tool is bent, the cutting edge of the cutting tool is inclined with respect to the mold material. Therefore, a dimensional error occurs in the vertical dimension (groove depth) of the sawtooth-shaped groove, and the angle of the slope is not as designed. For example, in a grating lens formed using a mold having such inferior shape accuracy of the saw-tooth groove, light diffraction does not become as designed, and the resolution is remarkably deteriorated or flare is generated. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention according to claim 1 is to make the shape accuracy of a saw-shaped groove of a saw-shaped optical element molding die extremely good. It is an object of the present invention to provide a method for manufacturing a sawtooth-shaped optical element forming die capable of performing the above-mentioned steps. An object of the invention according to claim 2 or 3 is to provide an apparatus for manufacturing a saw-tooth-shaped optical element molding die capable of extremely improving the shape accuracy of the saw-tooth-shaped groove of the saw-toothed optical element molding die. is there.

[0010]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to cutting a cutting blade to a predetermined depth while applying a cutting edge ridgeline of a cutting tool to a base material of a saw-shaped optical element molding die. In the method for manufacturing a saw-shaped optical element forming die to be processed, the cutting angle of the cutting blade, which is changed by the bending of the cutting tool during the cutting, is changed in a direction opposite to the change due to the bending, and by the bending. The correction is performed by the same amount as the change amount. The invention according to claim 2 is a cutting tool having a base material holding part for holding a base material of the saw-shaped optical element molding die, a cutting blade for cutting a slope of the saw-shaped groove, and holding the cutting tool. A rotating mechanism for tilting the cutting tool with respect to the base material, and moving means for moving the base material or the cutting tool so as to cut the cutting tool with respect to the base material. In the apparatus for manufacturing a saw-shaped optical element molding die, the cutting angle of the cutting blade, which is changed by the bending of the cutting tool during the cutting, is changed in a direction opposite to the change due to the bending, and the amount of change due to the bending. And a control device for controlling the rotation mechanism so as to correct by the same amount as that described above. According to a third aspect of the present invention, there is provided a cutting tool having a base material holding portion for holding a base material of a saw blade optical element forming die, a cutting blade for cutting a slope of a saw blade groove, and holding the cutting tool. A rotating mechanism for tilting the cutting tool with respect to the base material, and moving means for moving the base material or the cutting tool so as to cut the cutting tool with respect to the base material. In the apparatus for manufacturing a saw-toothed optical element molding die, a sensing device for sensing a torque that the cutting edge of the cutting bit receives from a slope of the saw-toothed groove,
The cutting angle of the cutting edge, which is changed by bending of the cutting tool in proportion to the magnitude of the torque, is corrected in the direction opposite to the change due to the bending, and by the same amount as the amount of change due to the bending. A control device for controlling the rotating mechanism is provided.

In the operation of the invention according to the first aspect, the cutting angle of the cutting blade, which is changed by the bending of the cutting tool at the time of cutting, is changed in a direction opposite to the change caused by the bending.
In addition, by correcting by the same amount as the amount of change due to bending, the amount of bending of the cutting bit and the amount of correction are canceled out, and a desired saw-tooth groove is finished. In the operation of the invention according to claim 2, the cutting angle of the cutting blade, which is changed by the bending of the cutting tool at the time of cutting, is changed in the opposite direction to the change due to the bending, and by the same amount as the amount of change due to the bending. By providing the control device for controlling the turning mechanism to make the correction, the control device accurately controls the turning mechanism and corrects the cutting angle of the cutting tool. In the operation of the invention according to claim 3, a sensing device for sensing the torque received by the cutting bit of the cutting bit from the slope of the saw-shaped groove, and the sensing device is changed by bending of the cutting bit in proportion to the magnitude of the torque. By providing a control device for controlling the rotation mechanism so as to correct the cutting angle of the cutting blade in the direction opposite to the change due to the bending, and by the same amount as the amount of change due to the bending,
Upon receiving the torque signal sensed by the sensing device, the control device accurately controls the turning mechanism and corrects the cutting angle of the cutting tool according to the torque signal.

[0012]

1 to 8 show a first embodiment of the present invention. FIG. 1 is a front view of a manufacturing apparatus for a saw-shaped optical element forming die, and FIG. 2 is a saw-shaped optical element forming die. FIG. 3 is a plan view of the manufacturing apparatus of FIG. 3, FIG.
FIG. 4 is a plan view of the cutting tool, FIG. 5 is a diagram showing the relationship between the saw-shaped groove and the cutting edge ridge line, FIG. 6 is an initial view of the cutting process of the saw-shaped groove, and FIG. FIG. 8 is a diagram showing the elastic deformation of the diamond tip to be machined, and FIG. 8 is a diagram showing the movement of the cutting edge for machining the sawtooth groove.

First, an apparatus for manufacturing a saw-shaped optical element molding die will be described. In FIGS. 1 and 2, an NC lathe 50, which is an apparatus for manufacturing a saw-toothed optical element molding die, mainly holds a base material 1, and rotates a work serving as a base material holding unit that rotates around a rotation axis 5. Table chucking part 4 and cutting tool 2
, A rotation mechanism 7 for rotating the bite support 3, and a control device 8 connected to the rotation mechanism 7 and controlling the rotation. The turning mechanism is constituted by the cutting tool support portion 3 and the rotating mechanism 7. Further, the rotating mechanism itself also serves as a moving means. NC lathe 50
Are at least the following four operations: a rotating operation of the mold blank 1, an advancing and retreating operation of the cutting tool 2 in the direction of the rotation axis 5 of the mold blank 1, an adjustment of a cutting angle of the cutting tool 2 with respect to the mold material 1, and a feeding operation of the cutting tool 2. It is an axis control system.

As shown in FIG. 3, a mold material 1 is formed by depositing an electroless P-Ni chemical plating 1a having a thickness of 0.1 mm on a SUS-based cylindrical base material and then forming a surface roughness Rmax of 0.05 μm or less. Thus, a plane 1b orthogonal to the rotation axis 5 is cut. The cutting tool 2 has a tool material 1
Are supported so as to be able to advance and retreat in the direction of the rotation shaft 5. As shown in FIG. 4, the cutting tool 2 has a shank 2a to which a natural or synthetic diamond tip 2b having a side of about 3 mm is adhered.
The wing angle 2c is formed to be smaller by about 2 to 4 degrees than the groove angle of the sawtooth groove of the part to be cut. Further, as shown in FIG. 2, the cutting tool supporting portion 3 supporting the cutting tool 2 is provided with a cutting edge ridge 2 of the diamond tip 2b.
In order that the angle φ between d and the rotating shaft 5 (remaining angle with respect to the cutting edge inclination angle θ) can be freely changed,
A rotating mechanism 7 is provided on the bite support 3.

In FIG. 2, a control device 8 is connected to the rotating mechanism 7 and controls the rotating operation of the bite supporting portion 3 provided continuously on the upper surface of the rotating mechanism 7. This is the entered design value,
That is, the cutting angle, the cutting depth, and the cutting position of the cutting tool are controlled based on the desired numerical data of the sawtooth groove. The control device 8 sets the rotation angle of the bite supporting portion 3 to the original design value by changing the angle φ (remaining angle with respect to the bite cutting edge inclination angle θ) between the bite cutting edge 2d and the rotating shaft 5 of the die blank 1 to the original design value. A program has been input for controlling the angle Δθ calculated by the following equation (1) to a value obtained by subtracting the angle Δθ. Equation (1) is expressed in FIG. 5 and FIG.
The following is displayed. Δθ = tan ⁻¹ (K + H / P) −tan ⁻¹ (H / P) (1) where Δθ: Increasing amount of cutting edge inclination angle (unit: rad) K: Proportion coefficient determined by mold material H: Vertical surface height of the sawtooth groove (unit: mm) P: pitch of the sawtooth groove (unit: mm) The proportional coefficient K is the mold material 1 according to the first embodiment of the present invention.
When the cut part of is electroless P-Ni,
It is. However, it fluctuates from 0.0014 to 0.0018 due to fluctuations in conditions of electroless P-Ni and the like.

Next, a description will be given of a method of manufacturing a saw-toothed optical element molding die using the manufacturing apparatus having the above-described configuration and a procedure of numerical correction. (1) A design value, that is, numerical data of a saw-tooth groove is input to the control device 8, and processing is performed according to the design value (no correction). <Processing Order> The inclination angle of the cutting edge ridge line 2d with respect to the mold blank 1 is adjusted to (parallel to) the inclination angle θ ₀ of the saw-shaped groove to be processed. In FIG. 5, the inclination angle θ ₀ can be represented by Expression (2). θ ₀ = tan ^-1 (H / P) (2) H: Vertical surface height of the sawtooth groove (unit: mm) P: Pitch of the sawtooth groove (unit: mm) The cutting is started straight (in the direction of the rotating shaft 5) toward the mold blank 1 to start cutting. By cutting the tip of the cutting tool 2,
The vertical surface 1c of the saw-like groove is cut. At the same time, the slope 1d is cut by the cutting edge 2d. Repeat the above ~.

(2) The saw-toothed grooves formed on the mold base 1 are measured for each groove, and the error of each groove (the error in the optical axis direction and the error in the vertical direction with respect to a plane perpendicular to the optical axis) is measured. ). (3) The correlation between the pitch P of each groove and the error amount of each groove is obtained. In the case of electroless P-Ni, the error amount is represented by the following equation (3). Error amount = 0.0016 × P−7 × 10 ⁻⁶ (3) P: Pitch of saw-tooth groove (unit: mm) Here, (−7 × 10 ⁻⁶ ) in equation (3) is Since it is a very small value, it can be ignored. The correlation between the pitch P and the amount of error can be described in words: "The wider the pitch, the larger the contact length between the slope and the cutting edge of the cutting tool becomes larger. The greater the vertical force acting on the cutting tool becomes, the larger the cutting tool becomes. Greatly bent ".
From the above correlation, the proportional coefficient K of the change in the error amount due to the change in the pitch is obtained.

(4) From the proportionality coefficient K, the pitch P and the vertical plane height H, an equation (1) for obtaining the increase amount Δθ of the cutting edge inclination angle is derived. (5) Based on the equation (1), a tool cutting blade inclination angle increase amount Δθ for each groove is obtained. (6) After obtaining the increase amount Δθ of the cutting edge inclination angle, the processing is started. (7) The processing time of the byte cutting edge inclination angle theta in each groove, byte cutting edge inclination angle increment Δθ relative byte cutting edge inclination angle theta ₀ of each groove at the time of processing according to the design value The cutting tool 2 is inclined so as to have an angle obtained by adding. (8) Hereinafter, a specific procedure of the main processing will be described.

(9) First, equation (1) is input to the control device 8. (10) The control device 8 obtains a design value, that is, an increase amount Δθ of the cutting edge inclination angle which is a correction value of the cutting edge inclination angle θ ₀ for each groove, based on the equation (1). The cutting edge inclination angle θ for each groove to be machined is the angle obtained by adding the increasing amount of the cutting edge inclination angle Δθ to the cutting edge inclination angle θ ₀ for each groove when machining according to the design value. Then, the rotating mechanism is driven.

FIGS. 6 to 8 show the cutting process of the saw-shaped groove. In FIG. 6, a mold blank 1 is an NC lathe 5
0 is rotatably mounted on the chucking portion 4 of the work table.
It is rotating at a predetermined rotation speed. The cutting process of the saw-shaped groove is performed by moving the cutting tool supporting portion 3 supporting the cutting tool 2 in the direction of the rotating shaft 5 of the molding material 1 while making contact with the plane 1b of the molding material 1. At this time, as shown in FIG.
The angle θ formed by the cutting edge 2d of the cutting edge of the cutting bit 2 and the plane 1b orthogonal to the rotation axis 5 is the amount of increase in the inclination angle of the cutting edge of the cutting edge 2d in proportion to the pitch P of the sawtooth groove. Δθ is calculated so as to be a value obtained by adding Δθ to the design value θ ₀ input to the control device 8, and the angle is corrected. Thereafter, as shown in FIG. 8, the diamond chip 2b of the cutting tool 2 abutting on the plane 1b is cut in the direction of the rotating shaft 5 of the mold blank 1 from the plane 1b to a predetermined depth, and is turned back on the same locus. Retreat.

Actually, when the cutting edge 2d of the cutting tool is cut into the mold blank 1, elastic deformation occurs due to the vertical reaction force received from the cutting contact area 11 on the cutting tool 2 and the tool supporting portion 3, and the cutting tool 2 The cutting edge 2d of the cutting tool is the NC lathe 5
A trajectory having an error with respect to the trajectory set at 0 will be followed. However, the trajectory error is canceled by the above-described correction of the cutting edge inclination angle θ, and as a result, a sawtooth-shaped groove as designed is obtained. Even when machining adjacent saw-tooth grooves,
After moving the bite supporting portion 3 in the direction of the rotating shaft 5, the saw-shaped groove is machined by the same method as the present method. The above operation is repeated to finish to a predetermined shape.

According to the first embodiment of the present invention, the cutting angle of the cutting edge of the cutting bit is corrected by an amount proportional to the pitch of the saw-shaped groove, so that the saw of the saw-shaped optical element molding die is corrected. The shape accuracy of the blade-shaped groove can be made extremely good.

In the first embodiment of the present invention, an example in which the cutting tool is moved in the direction of the rotation axis of the mold material has been described, but the mold material may be moved with respect to the cutting tool.

[0024]

Second Embodiment FIGS. 9 and 10 show a second embodiment of the present invention. FIG. 9 is a plan view of a saw blade optical element forming die manufacturing apparatus, and FIG. 10 shows the elastic strain of a cutting tool. FIG. Embodiment 2 of the present invention has the same basic configuration as Embodiment 1 of the present invention, and only different portions are shown. The same members are denoted by the same reference numerals and description thereof is omitted.

In FIG. 9, the shank 2 of the cutting tool 2
a is provided with a strain sensor 12 for sensing elastic strain generated during cutting. This elastic strain is shown in FIG.
As shown in the first embodiment, as in the first embodiment of the present invention, this corresponds to the elastic deformation Δθ of the cutting edge 2d of the cutting bit at the tip of the cutting bit 2. The strain sensor 12 includes a strain amplifier 13
, And is electrically connected to the rotating mechanism 7 of the bite support unit 3 so that the calculated distortion amount can be fed back from the control unit 8. . Other configurations are the same as those of the first embodiment.

Next, a method for manufacturing a saw-shaped optical element mold using the above-described manufacturing apparatus will be described. When the cutting tool 2 comes into contact with the flat surface 1b of the mold material 1 and the cutting is started, the cutting tool 2 is elastically deformed by the vertical reaction acting on the cutting blade contact area 11. The amount of strain Δ at this time
θ is sensed by the strain sensor 12 and
Is converted to a voltage via The voltage value at this time is multiplied by an appropriate coefficient by the control device 8 and fed back to the rotating mechanism 7. The value output at this time corresponds to the angle θ formed between the cutting edge 2d of the cutting tool and a plane orthogonal to the rotation axis 5 of the mold material 1. Further, since the angle θ formed by the cutting tool 2 corresponds to the generated cutting resistance in real time, even if the cutting resistance varies due to the unevenness of the metal structure on the surface of the mold material 1, the correction corresponding to the variation is performed. Done.

According to the first embodiment of the present invention, in addition to the same effects as the first embodiment of the present invention, even if the metal structure on the surface of the mold material is uneven, the cutting force is sensed in real time, Feedback can be provided to the correction amount of the cutting edge angle.

In the first embodiment of the present invention, the strain sensor is attached to the cutting tool. However, the same effect can be obtained by attaching the strain sensor to the cutting tool support.

[0029]

Third Embodiment FIG. 11 shows a third embodiment of the present invention, and is a plan view of an apparatus for manufacturing a saw-shaped optical element forming die. Embodiment 3 of the present invention has the same basic configuration as Embodiment 1 of the present invention, and shows only different portions, and the same members are denoted by the same reference numerals and description thereof will be omitted.

In FIG. 11, the material of the mold material 21 is free-cutting brass, and no film such as chemical plating is formed on the surface. Further, it is the same as in the first embodiment of the present invention that the amount of increase Δθ of the angle θ formed between the cutting edge ridge line 2d and the plane orthogonal to the rotation axis 5 of the mold material 21 is expressed by the formula (1). However, since the material of the mold material 21 is free-cutting brass, the proportional coefficient K is 0.0008. Note that the proportional coefficient K varies from 0.0006 to 0.0010 depending on the composition of the free-cutting brass. The configuration of the manufacturing apparatus is the same as that of the first embodiment.

Next, a method for manufacturing a saw-shaped optical element forming die using the die material 21 will be described. The rotation mechanism 7 for controlling the rotation angle of the bite support 3 from the control device 8
Then, the increase amount Δθ, which is the correction amount of the bite angle obtained by the equation (1), is output. In this case, since the mold material 21 is a free-cutting brass, the cutting resistance is smaller and the elastic deformation of the cutting tool 2 and the like is smaller than in the case of P-Ni, which is a chemical plating, and the amount of correction Δθ is correspondingly increased. Is also smaller. Other procedures of the manufacturing method and the operation thereof are the same as those of the first embodiment of the invention.

According to the third embodiment of the present invention, in addition to the effects of the first embodiment of the present invention, the die material to be cut is made of SU.
Even for materials other than S-based materials, for example, free-cutting brass, formula (1)
Can be used to correct an angular error due to elastic deformation of a cutting tool or the like.

The present application includes the creation of the following technical idea. (1) The method of manufacturing a saw-toothed optical element according to claim 1, wherein the amount of change due to the bending is calculated by the following equation (1): Δθ = tan ⁻¹ (K + H / P) − tan ^-1 (H / P) (1) where, Δθ: Increasing amount of cutting edge inclination angle (unit: rad) K: Proportion coefficient determined by mold material H: Vertical plane height of saw-shaped groove (Unit: mm) P: Pitch of saw-tooth groove (unit: mm) By inputting equation (1) to the control device, it is possible to accurately and quickly correct the cutting angle of the cutting tool.

[0034]

According to the first aspect of the present invention, the amount of deflection of the cutting tool and the amount of correction are canceled out and a desired saw-tooth groove is formed, so that the saw blade of the saw-shaped optical element molding die is formed. The precision of the shape of the groove can be extremely improved. According to the second aspect of the present invention, since the control device accurately controls the turning mechanism to correct the cutting angle of the cutting tool, the shape accuracy of the saw-shaped groove of the saw-shaped optical element molding die is extremely good. Can be finished. According to the third aspect of the present invention, the torque signal sensed by the sensing device is received, and according to the torque signal, the control device accurately controls the turning mechanism to correct the cutting angle of the cutting tool. It is possible to finish the shape accuracy of the saw-shaped groove of the forming die extremely well and to cope with a change in cutting resistance due to unevenness of the metal structure of the die material.

[Brief description of the drawings]

FIG. 1 is a front view of a manufacturing apparatus for a saw-shaped optical element forming die according to a first embodiment of the present invention.

FIG. 2 is a plan view of a manufacturing apparatus for a saw-shaped optical element forming die according to the first embodiment of the present invention.

FIG. 3 is a front view showing a relationship between the die material and the cutting tool according to the first embodiment of the present invention.

FIG. 4 is a plan view of the cutting tool according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between a saw-toothed groove and a cutting edge ridge according to the first embodiment of the invention;

FIG. 6 is an initial view of a cutting process of the saw-shaped groove according to the first embodiment of the invention;

FIG. 7 is a diagram showing an elastic deformation of a diamond tip for processing a saw-tooth groove according to the first embodiment of the invention;

FIG. 8 is a diagram showing the movement of the cutting edge for processing the saw-like groove according to the first embodiment of the invention;

FIG. 9 is a plan view of a manufacturing apparatus for a saw-shaped optical element forming die according to a second embodiment of the present invention.

FIG. 10 is a diagram showing elastic strain of a cutting tool according to the second embodiment of the present invention.

FIG. 11 is a plan view of an apparatus for manufacturing a saw blade optical element molding die according to a third embodiment of the present invention.

FIG. 12 is a view showing a conventional method for processing a saw-tooth groove.

FIG. 13 is a view showing a conventional method for processing a saw-tooth groove.

[Explanation of symbols]

 1 type material 2 cutting bit 2b diamond tip 2d bit cutting edge ridge line θ bit cutting edge inclination angle Δθ bit cutting edge inclination angle increase

Claims (3)

[Claims] 1. A method for manufacturing a saw blade-shaped optical element forming die, wherein a cutting edge of a cutting bit is applied to a base material of the saw blade-shaped optical element forming die, and the cutting is performed to a predetermined depth. A saw blade-shaped optical element molding die, characterized in that the cutting angle of the cutting blade, which is changed by bending of the cutting tool, is corrected in the opposite direction to the change due to the bending, and by the same amount as the amount of change due to the bending. Manufacturing method. 2. A cutting tool having a base material holding portion for holding a base material of a saw blade optical element forming die, a cutting blade for cutting a slope of a saw blade groove, and holding the cutting tool and holding the cutting tool. A saw blade comprising a rotating mechanism for inclining the cutting tool with respect to the base material, and a moving means for moving the base material or the cutting tool so as to cut the cutting tool with respect to the base material. In the apparatus for manufacturing an optical element molding die, the cutting angle of the cutting blade, which is changed by the bending of the cutting tool during the cutting, is changed in the opposite direction to the change due to the bending, and is equal to the change amount due to the bending. A manufacturing apparatus for a saw-shaped optical element molding die, further comprising a control device for controlling the rotation mechanism so as to correct only the correction. 3. A cutting tool having a base material holding portion for holding a base material of a saw-shaped optical element forming die, a cutting blade for cutting a slope of a saw-shaped groove, and holding the cutting tool. A saw blade comprising a rotating mechanism for inclining the cutting tool with respect to the base material, and a moving means for moving the base material or the cutting tool so as to cut the cutting tool with respect to the base material. In the optical device mold manufacturing apparatus, a sensing device for sensing the torque received by the cutting blade of the cutting bit from the slope of the saw-like groove, and the cutting bit proportional to the magnitude of the torque is changed by bending. The cutting angle of the cutting blade to the direction opposite to the change due to the bending,
And a control device for controlling the rotating mechanism so as to correct the change amount by the same amount as the change amount due to the bending.