JP2003026430A - Mold for molding high-precision prism, method for manufacturing the same and method for manufacturing high-precision prism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low-cost prism by realizing cost reduction and stability of dimensional accuracy of a mold in simultaneously molding three surfaces of a prism with the mold composed of crystallized glass replicated with a master block. SOLUTION: Replica molding is carried out by using the crystallized glass with high heat resistance as a mold material. Thereby both cost reducing effect owing to the molding and cost reduction owing to the stability of the dimensional accuracy are made possible and furthermore, contribute to the cost reduction of the prism.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism molding die for manufacturing a highly accurate prism by press molding, a manufacturing method thereof, and a highly accurate prism manufacturing method using the prism molding die. .

[0002]

2. Description of the Related Art Conventionally, as a prism molding die and a method for manufacturing the same, the inventions disclosed in, for example, Japanese Patent Application Laid-Open Nos. 9-187821 and 9-25132 are disclosed.

The invention described in Japanese Patent Application Laid-Open No. 9-187821 discloses a molding die formed of one member which is not divided and has both planes sandwiching a roof ridge line forming portion of a roof prism at a predetermined angle. With a mold, the manufacturing method is to form a plating film that can be cut with a soft metal or diamond cutting tool, and precisely cut the desired roof ridge line forming part and both planes sandwiching the ridge line part by precision cutting method. ,
It is intended to realize a die for molding a roof prism that is injection-molded mainly using a resin material.

The invention described in Japanese Patent Application Laid-Open No. 9-25132 relates to a method for manufacturing a glass prism and an apparatus for manufacturing the glass prism, and a molten glass gob is heated by a centrifugal force to a receiving mold having at least adjacent receiving surfaces. It is characterized in that they are closely contacted with each other and molded. As a receiving material, a material having low heat resistance, mirror surface workability, and reactivity with molten glass, such as a sintered body of AlN, BN, or Cr ₂ O _3, or the surface of the sintered body is coated. A mold is used. In addition, by preparing a receiving mold with multiple nesting molds, we have realized an inexpensive glass prism by rationalizing the molding.

However, the above-mentioned prior art has the following problems.

Although the invention described in Japanese Patent Application Laid-Open No. 9-187821 has an effect of suppressing burrs at the roof ridge line forming portion, Since the cutting tool R is extremely small, it is difficult to obtain a stable machined surface due to large tool wear. 2. Since the bite R is small, it is necessary to suppress the cutting speed in order to obtain a desired optical mirror surface, and thus the processing time becomes long. 3. Not suitable for prism molds made of glass.

The invention described in Japanese Patent Application Laid-Open No. 9-25132 is a molding that can be performed in the air according to the wording of the specification, and although only two surfaces of the prism have an effect of efficient productivity, 1. Conventional polishing is required on the remaining one surface to obtain the final prism. 2. Even if a mold material having excellent heat resistance and mirror surface workability is used, under the conditions of air, surface oxidation occurs due to the high temperature of oxidation or molten glass, and depending on the glass material to be molded, it may not be a mold. Reaction occurs. 3. Although the molding productivity is high, the overall productivity remains questionable in combination with conventional polishing.

[0008]

In view of the problems in the prior art, in order to directly press all of the highly accurate prism surfaces, the mold material is excellent in heat conductivity and heat resistance, and the press molding optics is used. It is necessary to have a material that is inert to the element material and has high-temperature strength so that the pressing surface shape of the die does not collapse when pressed. On the other hand, it has excellent workability,
It also has problems such as precision processing being easy and inexpensive to manufacture.

As a material satisfying the conditions necessary for the mold as described above to some extent, a cemented carbide containing WC as a main component is used as a mold material, and the mold material is coated with a noble metal protective film. There is a mold, and by using this mold, mass production by press molding becomes possible.

However, it is difficult to perform precision machining of a cemented carbide used as a die material, a special machining device is required, and polishing is sometimes required after the machining to improve the surface roughness.

Further, since the processing is mainly performed by grinding with a diamond grindstone, there is a problem that the cutting amount at the time of processing cannot be increased due to the abrasion of the grindstone, the processing time is long, and the processing cost is very high. Further, due to the difficulty of processing, there are large variations in the shape of the mold, which is a factor that makes the mold cost very high.

[0012]

[Means for Solving the Problems] A means for solving the above-mentioned problems is to use, as a base material, a cemented carbide containing tungsten-carbide (WC) as a main component, and to form a molding surface having the same shape as a prism shape on the base material. After grinding and polishing, a master having a protective film having high strength, durability and no reactivity with glass is formed on the molding surface, and the crystal of the crystallized glass is formed using the master. After softening the material before heat treatment, it is pressed and molded into the inverted shape of the prism, then subjected to crystallization treatment, and then the surface formed into the inverted shape has high strength and heat resistance and glass. A solution is to provide a nested mold for prism molding obtained in a manufacturing process for forming a protective film having no reactivity.

Next, it is composed of an optical material, upper and lower nesting molds, and a receiving mold that encloses the upper and lower nesting molds, and the heat shrinkage amount of the receiving mold is the total heat of the optical material and the upper and lower nesting molds. The solution is to provide a mold set to be larger than the shrinkage amount.

Next, an optical material is put into a prism molding die including a nesting die to form a molding block, and the entire molding block is heated, and when the optical material is softened, the surface of the nesting die is transferred. The present invention provides a means for solving the problem by providing a method for manufacturing a prism that is obtained by subjecting the shaped block to cooling by performing the pressing deformation.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a highly precise prism molding die and a manufacturing method thereof according to an embodiment of the present invention.
This will be described with reference to (A), (B) and FIGS. 2 (A) to (E).

FIG. 1 (A) is a vertical cross-sectional view of a prism molding die 1 of the present invention, which comprises a nesting die of an upper die 2 and a lower die 3 contained in a receiving die 4 made of a metal member. Has been done.

The upper mold 2 and the lower mold 3 are made of a crystallized glass material, and the S0 surface of the upper mold 2 and the S2 surface and the S3 surface of the lower mold 3 are inactive and reactive with the molding material 7 serving as a prism. There is no protective film.

FIG. 1 (B) is a vertical cross-sectional view showing a state where a prism is molded by using the molding die 1. The entire molding die 1 is heated in an inert gas to soften the molding material 7. By pressing the upper mold 2 at a temperature, the three surfaces S0, S2, and S3 of the upper and lower molds are simultaneously precisely transferred to obtain the prism 8.

The crystallized glass used for the upper and lower molds 2 and 3 had a composition of lithium silicate and had thermal characteristics before crystallization of a yield point of 518 ° C. and a glass transition point of 472 ° C. After crystallization, no softening point or transition point is shown and the softening temperature is remarkably improved. The thermal expansion coefficient is 98 × 10 ⁻⁷ / ° C., and the micro Vickers hardness at room temperature is 700.

On each surface of S0, S2, and S3, a noble metal alloy film which is inert to the forming material and has a good releasability is formed by a sputtering method to a film thickness in the range of 0.5 to 2 μm. The material of the receiving mold 4 has a coefficient of thermal expansion of 165 × 10 ^-7
/ ° C stainless steel material is used, and the U-shaped inner surface and both upper and lower surfaces are precisely ground.

The reason for this is to maintain precise parallelism between the upper and lower molds and the receiving mold during molding.

Incidentally, Japanese Unexamined Patent Publication No. 9-187821 also discloses a forming die having both surfaces sandwiching a predetermined angle like the lower die 3, but the conventional forming die is a soft metal. In contrast, the present invention is composed of crystallized glass having high heat resistance and an inactive film on the surface thereof, so that it can be applied to either resin or glass as an optical material. It is a mold structure that enables highly accurate prism molding.

2 (A) to 2 (E) illustrate a method of manufacturing a nested mold for obtaining a highly accurate prism molding mold.

FIG. 2A shows a perspective view of a matrix 11 made of cemented carbide containing WC in an amount of 80 wt% or more.

It has a rectangular shape, and in the drawing, the apex angle 2θ and both plane portions of S2 surface and S3 that sandwich it are the same as the prism shape to be finally obtained. S2,
Both surfaces of S3 are symmetrically arranged with the S1 surface as a reference surface, and the S4 and S5 surfaces are machined at right angles to and parallel to the S1 surface. The master block 11 has stepped portions 12 at both ends in the longitudinal direction.
And functions as a holding portion when the protective film is formed.

FIG. 2B is a vertical sectional view for explaining an important processing method performed for obtaining the master block 11 described above.

The tilt table 14 of the surface grinder adjusts the tilt angle θ. The mother die material 11 preliminarily preliminarily processed was adhered precisely using S1 as a reference and using wax as the surface plate 13. As the mother die material 11, a backing plate 15 for ensuring straightness in a direction orthogonal to the grindstone shaft 17 was used, and it was attached to the electromagnetic chuck of the tilt table.

Precision grinding is performed while cutting the grindstone shaft 17 downward to a predetermined position by the resinoid-bonded diamond grindstone 16. Grinding is performed by traversing the table in a direction orthogonal to the grindstone axis and in the direction of the arrow shown in the figure. The drawing shows a state in which the S2 surface is processed, but both sides of S2 and S3 are evenly distributed and processed by reversing the mother die and cutting to the same predetermined position.

Thereafter, the grinded S2 and S3 were individually subjected to polishing processing to perform plane processing. The polishing was carried out by using a polishing jig (not shown) while supplying a diamond turbid liquid having an average particle diameter of 1 μm as a slurry to a rotating platen made of a soft metal whose flatness was controlled. The apex angle of the polished mother die is processed at an angle of 2θ.
Both surfaces of S2 and S3 had a surface roughness Rmax of 0.01 μm and a flatness of less than 1 Newton (convex shape).

After that, the mother die material 11 was precisely cleaned, and the jig 12 of the sputtering apparatus was engaged with the step portion 12 and loaded. The apparatus is a magnetron high-frequency sputtering method, a platinum (Pt) -iridium (Ir) alloy film is used as a target, and both S2 and S3 are 1 μm at the same time under the conditions of a vacuum degree of 5 × 10 ⁻⁴ Torr and an electric power of 600 W. Formed into a film thickness,
The matrix 11 shown in (A) could be obtained.

Although the surface roughness and the flatness after the film formation changed slightly, they were within the desired accuracy range.

The above-mentioned mother die 11 has a structure shown in FIG.
Although the process for making the nested mold of the lower mold 3 shown in (B) is shown, the mother mold for making the upper mold 2 can also be obtained by the same process and processing method as above, but it is a simple planar shape. Detailed description is omitted.

2 (C), (D) and (E) are shown in FIG.
FIG. 6 is a front cross-sectional view of an essential part for explaining a step of press-molding the lower mold 3 that is the nesting mold described in (A).

Upper heating plate 2 in which heaters 24 are embedded at the top and bottom
The receiving die 22 was arranged between the No. 5 and the lower heating plate 26, and the molding material 23 was put into the receiving die 22. The mother mold 11 described above has a predetermined angle 2 formed by the molding surfaces of S2 and S3.
θ is formed, and it is fitted into the holding die 21 machined by WC of the same material and is in contact with the upper heating plate 25.

The receiving die 22 is made of WC made of the same material as the mother die 11 and the holding die 21. The forming material 23 is a glass before crystallization (depression point: 518 ° C.
The glass transition point: 472 ° C.) is previously processed into a rectangular shape, and the surface in contact with the molding surfaces of S2 and S3 is mirror-polished.

All of them are arranged in a chamber (not shown) capable of being heated in an inert gas, and a pressing force F is applied via an upper heating plate 25 by a pressurizing mechanism (not shown) (for example, an air cylinder). It is a thing.

First, the upper and lower heating plates 2 in the state of FIG.
Turn on the heaters 24 of Nos. 5 and 26 and heat to 580 ° C.
After holding for a minute, a pressing force of 8000 N was applied.

FIG. 2D shows a molding material 2 formed by the mother die 11.
Reference numeral 3 indicates a deformed state. 5 more in this state
After holding for a minute, the upper and lower heating plates 25 while continuing to press,
The temperature of 26 was raised to 750 ° C. and kept for 2 hours to crystallize the molding material 23.

Thereafter, while the pressing was continued, the power supply to the upper and lower heating plates was cut off, and when the temperature was cooled down to 400 ° C., the pressure was released and further cooled down to room temperature. Molding material 2
No. 3 was transparent at the beginning, but when taken out, it showed a completely opaque state and sufficient crystallization was performed.

In FIG. 2 (E), the molding surface of the molding material taken out from the receiving mold 22 has a shape opposite to that of the prism and the mother mold. Both surfaces of S2 and S3 form an angle of 2θ. It was possible to obtain a nested type. Forming surface S
2 and S3 are slightly worse than the accuracy of the matrix, Newton = 1.5
The book (concave shape) was transferred.

After that, Pt-Ir, which is a noble metal alloy, was formed into a film having a thickness of 1 μm on the molding surfaces S2 and S3 by a sputtering method to obtain the lower mold 3. The condition of the present embodiment, that is, 10 lower molds 3 were created with one matrix,
Almost the same accuracy was confirmed. Although a detailed description is omitted, the required upper surface accuracy of the prism is obtained by the same process and method for the upper mold 2 which is a nested mold.

3A to 3C illustrate a method of manufacturing a glass prism using the prism molding die obtained as described above.

FIG. 3A shows the molding block 31.
A lower mold 3 and an upper mold 2 made of crystallized glass are contained in a U-shaped receiving mold 4 made of stainless steel material (coefficient of thermal expansion 165 × 10 ⁻⁷ / ° C.). A molding material 7, which is an optical glass material, is placed in between.

The molding material 7 is crown borosilicate glass (Tg point: 501 ° C., At point: 549 ° C.) with an outer diameter of 5 mm.
The rod was shaped like a bar and its outer diameter was centerless polished.

The entire molding block 31 is energized by the upper and lower heating plates 25 and 26 in which the heater 24 is embedded, and the temperature is raised to 590 ° C. At the same time as the temperature rise, a pressing force F of 7,000 N is used by a pressurizing mechanism (not shown). And pressed to deform the molding material 7.

FIG. 3B shows a state in which the deformation has been completed. The molding material 7 has already been molded into a prism shape, and three molding surfaces S0, S2 and S3 are simultaneously formed.

At this time, the upper end surface of the receiving mold 4 is in contact with the upper heating plate, and in this state, the heater power of the upper and lower heating plates 25 and 26 is turned off while maintaining the pressing force, and 480 ° C.
And the pressure was released. The receiving die 4 is set to have a size such that a contraction amount larger than the contraction amount of the upper and lower molds 2 and 3 and the molding material 7 as it cools is obtained, and the molding material follows the contraction of the receiving mold 4. Pressing is continued until it is sufficiently solidified, and highly accurate transferability can be obtained.

After releasing the pressure, the glass prism 8 shown in FIG. 3C could be obtained by further cooling to room temperature.

The obtained glass prism 8 has a length of 30 m.
The transferability was 4 to 5 Newton's when evaluated by optical flat. Further, after depositing a predetermined optical film on the glass prism 8, the longitudinal direction was cut into a desired dimension and mounted in an optical system of an optical pickup, and the accuracy in a practical range was confirmed.

[0050]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, a master die is prepared, and by using the master die, a crystallized glass is replicated, so that a molding die having high accuracy and high heat resistance is stable and can be manufactured at a lower cost. Therefore, the cost of the prism can be greatly reduced. Therefore, the prism molding die of the present invention, the manufacturing method thereof, and the prism manufacturing method using the molding die can be provided with high industrial utility value.

[Brief description of drawings]

1A and 1B are vertical cross-sectional views of a prism molding die described in an embodiment of the present invention.

2A to 2E are process diagrams illustrating a method for manufacturing a prism molding die described in an embodiment of the present invention.

3A to 3C are cross-sectional views of a main part for explaining a method of manufacturing a prism described in an embodiment of the present invention.

[Explanation of symbols]

1 Mold 2 Upper mold 3 Lower mold 4,22 Receiving type 7,23 Molding material 8 prism 11 mother pattern 21 holding type 25 Upper heating plate 26 Lower heating plate 31 Molded block S0, S2, S3 Prism molding surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Makoto Umeya             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Hiroshi Ryouchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2H042 CA15 CA17

Claims (3)

[Claims] 1. A method of manufacturing a molding die for press-molding a prism using an optical material, the method comprising:
Carbide (hereinafter referred to as WC) as a main component is used as a base material, and the base material is composed of two forming surfaces that form a predetermined angle, and is formed into the same shape as the prism, and then the forming is performed. A mother die having a protective film having high strength, durability and reactivity which is formed on the surface is formed, and the material before crystallization of the crystallized glass is softened by heating using the mother die, followed by press molding. A prism characterized by being subjected to crystallization treatment after being formed into an inverted shape of the prism, and forming a protective film having high strength, heat resistance, and no reactivity with the optical glass on the surface formed into the inverted shape. A method for manufacturing a nested mold for molding. 2. A molding die for press-molding a prism using an optical material, wherein the nesting mold according to claim 1 is arranged vertically to form the entire surface of the prism, and the upper and lower nests. A prism molding, characterized in that it is constituted by a receiving mold enclosing a mold, and the heat shrinkage of the receiving mold is larger than the total heat shrinkage of the upper and lower nesting molds and the optical glass. Type. 3. A method for manufacturing a prism using the molding die according to claim 2, wherein the upper and lower nesting molds and the optical material sandwiched between the nesting molds are contained and accommodated. A step of forming a molding block with a mold; a step of heating the entire molding block to deform when the optical material is softened; and a step of cooling the entire molding block while pressing the entire molding block. And a method for manufacturing a prism.