JP3002091B2 - Manufacturing method of optical element mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mold for molding an optical element having a discontinuous functional surface.

[0002]

2. Description of the Related Art Hitherto, an optical element (such as a prism) having a discontinuous functional surface has been manufactured by directly processing glass by grinding or polishing. However, due to the diversification of required functions, the shape is becoming more complicated and more precise, and it is becoming difficult to machine steps (such as edges) at discontinuous portions by conventional machining.

On the other hand, recently, a glass press molding method for obtaining an optical element by pressing a glass material using a mold having an optical mirror surface has been put to practical use. This method is effective in that an optical element can be manufactured at low cost.

[0004] Therefore, in the production of an optical element having such a discontinuous functional surface, it is considered that efficient mass production is possible by using a glass press molding method.

As a method of manufacturing a molding die for molding an optical element having a discontinuous functional surface, for example, Japanese Unexamined Patent Publication No. Hei 3-887
There is an invention described in JP-A-33-33. The above invention is a method of manufacturing a molding die by forming mold elements divided from boundaries of discontinuous individual molding surfaces individually by machining, and fixedly connecting and combining them with a heat-resistant inorganic adhesive or the like. .

[0006]

However, in the invention described in Japanese Patent Application Laid-Open No. 3-88733, it is necessary to increase the dimensional accuracy of each part other than the molding surface because the divided parts are combined. Further, in the accuracy of the assembly, each error becomes a total error. Therefore, it is not possible to cope with a case where the precision of the molded optical element alone requires high precision. In terms of cost,
Each of the divided molds is required to have high-precision dimensions, and cannot be reworked after being combined once, which is very expensive.

The object of the invention according to claims 1 and 2 is as follows.
An object of the present invention is to produce an optical element mold having a discontinuous molding surface as an integral mold.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing an optical element mold having a plurality of discontinuous flat surfaces as a molding surface. After forming the corners of the grinding wheel with a shaft to the edge with a truing dress while rotating the grinding wheel with the shaft held, individual forming of the mold material fixed to the main spindle of the processing machine by the edge of the grinding wheel with a shaft Process the surface in one piece. Each molding surface is manufactured by processing a mold material by rotating it by a predetermined angle. Alternatively, it is manufactured by moving a grinding wheel up and down to process.

According to the first aspect of the present invention, an optical element mold having a discontinuous molding surface can be integrally processed. The effect of claim 2 is that the end face of the grinding wheel with shaft is formed in a concave shape,
Chips and abrasive powder on the processing surface are stored in the concave portion and are not affected by the recess, so that the mirror surface and flatness of the molding surface can be improved.

[0010]

1 to 6 show this embodiment, FIG. 1 is a perspective view of a molding die, FIG. 2 is a perspective view of a molded optical element, and FIG.
4 is a plan view of the apparatus used for manufacturing, FIGS. 4 and 5 are front views of the apparatus, FIG.
FIG. 6B is an enlarged sectional view of a portion A in FIG. 6A.

The molding die 1 of this embodiment is used as an upper die or a lower die for molding the optical element (for example, a prism) shown in FIG. A molding surface 2 having a shape corresponding to the functional surface of the optical element is formed on the upper surface of the molding die 1. The molding surface 2 consists of two discontinuous surfaces 2a and 2b, which are inclined at equal angles in opposite directions toward the boundary 3 respectively.

Hereinafter, an apparatus configuration for manufacturing the mold 1 will be described. The molding die material 1a is held via a spindle drive motor 4 and an angle detection device (encoder) 5 on an ultra-precision NC processing machine so as to rotate coaxially with a rotation center 6a of a spindle 6 that rotates precisely.

The grinding wheel 7 has a diameter equal to or more than の of the outer diameter of the molding surface 2 of the molding die 1, and
Alternatively, 2b can be formed by one processing. Further, as shown in FIGS. 6A and 6B, the shape of the edge portion 7e composed of the outer peripheral portion 7a and the end face portion 7b is a concave shape. Further, the edge portion 7e was reduced to 0.05 mmR or less by truing and dressing using a grindstone for truing on a processing machine.

The grinding wheel 7 arranged opposite to the molding die material 1a is held by a grinding wheel rotating spindle 8 which rotates precisely at high speed, and the grinding wheel rotating spindle 8 is moved vertically (H direction in FIGS. 4 and 5). It is held by a grindstone rotating spindle holder 9 having a sliding function.
In addition, these show a part as a processing stage, and the whole is configured on an ultra-precision NC processing machine not shown.

The operation of this embodiment will be described below. In the molding die 1 and the grinding wheel 7 arranged as described above, the rotation center 6a of the molding material 1a and the edge portion 7e of the grinding wheel 7 are adjusted by adjusting the grinding wheel rotating spindle holder 9 in the vertical direction (H direction). Match (see FIG. 4). Further, in order to minimize the influence of the edge portion 7e on the boundary line 3, the end surface portion (edge portion 7e) of the grinding wheel 7 is adjusted so as to overlap by S (see FIG. 5). It is desirable that the amount of overlap S be at least twice the size of R at the edge 7e of the grinding wheel 7. However, it is up to a range of about 0.2 mm having no optical influence.

Next, the molding surface 2 (2a, 2a) will be described with reference to FIG.
The processing of b) will be described. And aθ ₁ = θ ₂ in which one of the discontinuous surface formed by the inclined angle A.theta. ₁ in the forming surface 2a and the end face portion 7b of the grinding wheel 7 tilts the grinding wheel rotation spindle 8 so as to be parallel (Fig. 3 ).
Thereafter, a tool path (arrow in FIG. 3) is set by the NC program so as to form a molding surface having a predetermined inclination angle (aθ ₁ ), and grinding is performed. Grinding is a grinding wheel 7
Is rotated, and the molding material 1a is fixed. In addition, programming is performed so that the angle (θ ₃ ) of the tool path is equal to the inclination angle (aθ ₁ ) of the molding surface 2a.
Thus, one molding surface 2a of the molding surface 2 is processed.

Next, the molding material 1a is rotated by 180 ° by an angle detector (encoder) 5, and the other molding surface 2b of the molding surface 2 is processed in the same manner as the molding surface 2a. Through the above steps, the molding die 1 having the external shape shown in FIG. 1 can be manufactured.

Specific results of the present embodiment are shown below. Mold 1 is made of sintered tungsten carbide,
Outer diameter 8mm, maximum step at boundary of discontinuous surface is approximately 0.00
3 mm, each having an inclination angle of 1 '. The grinding wheel 7 is a vitrified diamond wheel # 3000 with a shaft (outside diameter φ8 mm) with a shaft, and truing dressing is performed on an ultra-precision NC processing machine, and the overlap amount is S =
It processed as 0.1 mm.

As a result, each molding surface has an inclination angle of 1'1.
A molded surface with a 5 ″ surface roughness Rmax of 0.06 μm was obtained. The sag width of the step at the boundary between the molded surfaces was 0.05 mm or less. It is thought to have been caused by an error in the setting error of the grinding wheel or the grinding wheel and an error in the measurement.

According to this embodiment, an optical element mold having a discontinuous molding surface can be manufactured as an integral mold.
Processing can be performed again by the same processing method, and the total cost as a molding die can be reduced. Further, the blank shape of the molding die can be a simple shape as compared with the split die.

[0021]

Embodiment 2 FIGS. 7 to 14 show this embodiment, FIGS. 7 to 10 are process drawings, FIG. 11 is a perspective view of a molding die, and FIG.
FIG. 13 is a view as viewed in the direction of the arrow D in FIG. 1, FIG. 13 is a view as viewed in the direction of the arrow C in FIG. 11, and FIG. This embodiment will be described with reference to FIGS. In the present embodiment, machining is performed on the molding die 1 of the first embodiment while moving the grinding wheel 7 up and down.

The operation of this embodiment will be described below. First,
As shown in FIGS. 7 and 8, one discontinuous molding surface 2a is processed as in the first embodiment. Next, as shown in FIG. 9 and FIG. 10, the edge 7e (upper end in FIG. 9) of the grinding wheel 7 arranged oppositely is adjusted by adjusting the vertical direction (H direction) of the grinding wheel rotary spindle holder 9 to form the molding material 1a.
With the rotation center 6a. Further, similarly to the first embodiment, in order to minimize the influence of the edge portion 7e on the boundary line 3, the end surface portion (edge portion 7e) of the grinding wheel 7 is adjusted to overlap by S.

The tilting of the grinding wheel rotation spindle 8 as the other discontinuous molding surface 2b is formed by the inclined angle Bishita ₁ in the forming surface and the end surface portion 7b of the grinding wheel 7 is parallel (bθ ₁ 10 = Θ ₄ = aθ ₁ = θ ₂ ). Thereafter, a tool path is set by the NC program (arrow in FIG. 10) so as to form the molding surface 2b having a predetermined inclination angle (bθ ₁ ), and grinding is performed. At this time, the angle (θ ₅ ) of the tool path and the inclination angle (bθ) of the molding surface 2b
Program so that ₁ ) is equal to Through the above steps, the molding die 1 having the external shape shown in FIG. 1 can be manufactured.

According to this embodiment, as shown in FIG.
The relative angle between the molding surfaces 2a and 2b orthogonal to the boundary 3 can be set to zero. That is, in FIG. 12, the difference between the inclination angles of the molding surfaces 2a and 2b is zero.

As a modified example of this embodiment, according to the above-described processing method, it is also possible to process a molding die having three molding surfaces having different inclination angles as shown in FIG.

[0026]

Embodiment 3 FIG. 15 is a perspective view of a molding die according to this embodiment. This embodiment will be described with reference to FIG. In each of the above embodiments, processing of a mold having two discontinuous molding surfaces has been described. In this embodiment, processing of a mold having four discontinuous molding surfaces is performed.

The operation of this embodiment will be described below. In the present embodiment, as in the first embodiment, a method of processing while rotating the molding die material 1a is used, and the angle detection device (encoder) 5 rotates the molding die material 1a by a predetermined division angle of 90 °. Then, each molding surface is processed.

According to the present embodiment, as shown in FIG.
A mold having four mold surfaces can be machined with high precision. Further, in the present embodiment, not only the processing of the molding die having the four divided molding surfaces, but also the processing of the molding die having the desired divided molding surfaces by setting the number of divisions to three or more. Can be.

In order to achieve the object of the present invention, the following configuration can be adopted. That is, the grinding wheel with the shaft has a tool diameter wider than the forming surface. Alternatively, the grinding wheel with a shaft has a diameter of 1/2 or more of the outer diameter of the forming surface. According to the above-mentioned grinding wheel with a shaft, it is possible to machine each of the divided molding surfaces in one pass. Further, the grinding wheel with a shaft has its edge portion opposed to the molding surface so as to overlap the rotation center axis of the molding material by a predetermined amount. According to the above-mentioned arrangement of the grinding wheels with the shaft, the shape of the boundary portion of the discontinuous forming surface, that is, the shape of the step portion can be processed with desired accuracy.

Further, a method of integrally processing the molding surface is as follows.
The processing is performed by rotating the molding material fixed to the main shaft of the processing machine by a predetermined angle. In the method of integrally processing the molding surface, the angle of rotation of the molding material is detected by an angle detection device. The above-described method of integrally processing can be integrally processed even if the two divisions are three or more divisions from the base. Further, the method of integrally processing the molding surface is to move the grinding wheel with a shaft, which is arranged opposite, vertically. In the method of integrally processing, the relative angle of each molding surface orthogonal to the boundary line divided in the case of the division into two can be set to zero.

[0031]

According to the first and second aspects of the present invention, an optical element molding die having a plurality of discontinuous flat surfaces as a molding can be manufactured as an integrated mold. Further, the same mold can be processed again by the same processing method. Therefore, the total cost as a molding die can be reduced. In addition, since integral processing can be performed, the shape of the molding die is simpler than that of the split mold.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment.

FIG. 2 is a perspective view showing the first embodiment.

FIG. 3 is a plan view showing the first embodiment.

FIG. 4 is a front view showing the first embodiment.

FIG. 5 is a front view showing the first embodiment.

FIGS. 6A and 6B show the first embodiment, in which a is a half sectional view, and b is an enlarged sectional view of a portion A of FIG.

FIG. 7 is a process chart showing Example 2.

FIG. 8 is a process chart showing Example 2.

FIG. 9 is a process chart showing Example 2.

FIG. 10 is a process chart showing Example 2.

FIG. 11 is a perspective view showing a second embodiment.

FIG. 12 is a view as seen from an arrow D in FIG. 11;

13 is a view as viewed in the direction of arrow C in FIG. 11;

FIG. 14 is a perspective view showing a modification of the second embodiment.

FIG. 15 is a perspective view showing a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Molding surface 3 Boundary line 4 Spindle drive motor 5 Angle detector 6 Spindle 7 Grinding wheel 8 Wheel rotating spindle 9 Wheel rotating spindle holder

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C03B 11/08

Claims (2)

(57) [Claims] In producing an optical element mold having a plurality of discontinuous flat surfaces as molding surfaces, a grinding wheel with a shaft, which is disposed to face a molding surface of a molding material and held by a grinding turbine, is rotated. After forming the corners of the grinding wheel with shaft on the edge with a truing dress, the individual forming surfaces of the mold material fixed to the main spindle of the processing machine are machined by the edge of the grinding wheel with shaft. Method of manufacturing optical element molding die. 2. The grinding wheel with a shaft has a concave end face, and a corner-shaped R formed by the end face and the side face has a radius R of 0.05.
2. The method for manufacturing an optical element molding die according to claim 1, wherein the diameter is not more than mm.