JPH09300371A - Mold for optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for an optical element capable of inexpensively producing a matrix within a short time. SOLUTION: A liquid plastic raw material is injected into the cavity formed by two matrices (projected matrix 11, recessed matrix 12) and the molding gasket 1 held between them and cured to mold an optical element. The projected matrix 11, the recessed matrix 12 and the molding gasket 1 are grasped by a press spring 4. As the molding gasket 1 and the press spring 4, ones used heretofore are used as they are but the projected matrix 11 and the recessed matrix 12 are different from conventional ones and produced by the injection molding of a synthetic resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic optical element, and more particularly to a mold for a plastic lens for spectacles.

[0002]

2. Description of the Related Art As a conventional method for molding a plastic lens for eyeglasses, there is a casting method using a molding gasket. FIG. 5 shows an outline of the conventional casting method. Here, a molding die 1 is composed of a synthetic resin molding gasket 1 manufactured by injection molding, a glass convex mold 2, a concave mold 3, and a metal pressing spring 4. Convex mold 2
The convex surface side and the concave surface side of the concave mother die 3 are optically polished.

First, in the mold assembly step, the above-mentioned two mother molds 2 and 3 are fitted into the molding gasket 1, and these are pressed by the pressing springs 4 to form a molding die. Then, in a pouring step, a liquid plastic material (for example, a monomer) 5 is put inside a molding die (hereinafter referred to as a cavity). After injecting the monomer 5, the mold is put in a polymerization furnace to cure the monomer 5. In the releasing process, the molding die is disassembled and the plastic lens 6 is taken out.

Injecting the monomer 5 in the injection step,
For example, a method of turning over a part of the molding gasket 1 to insert an injection pipe, or a method of providing an injection port in the molding gasket 1 and inserting the injection pipe into the injection port to inject it are used.

[0005]

However, since the glass mold is used in the conventional molding die, in the manufacturing of the glass mold, a grinding step using a curve generator, a sanding step, a polishing step, etc. Various steps were required. Further, optical elements such as plastic lenses for spectacles are usually mass-produced, and in this case, a large number of molding dies that match the manufacturing takt time are prepared. It would be costly to perform each of the above steps by a number. Also, the glass matrix is
It is often damaged during demolding, and new mother molds are frequently replenished.

In view of the above problems, it is an object of the present invention to provide a molding die for an optical element, which is inexpensive and allows the master die to be manufactured in a short time.

[0007]

According to one aspect of the molding die of the present invention for solving the above problems, a liquid is formed in a cavity formed by two mother dies and a molding gasket sandwiched between them. In the molding die for injecting the plastic raw material, and curing the plastic raw material in the cavity to mold an optical element, each of the two mother dies is made of a synthetic resin. Will be provided.

According to another aspect of the molding die of the present invention for solving the above problems, a liquid plastic raw material is injected between two mother die portions arranged at regular intervals by a gasket portion, In a mold for curing the injected raw material into the shape of the target optical element, one of the two mold parts and the gasket part are integrally molded using a synthetic resin, A mold is provided, wherein the other master mold part of the two master mold parts seals an opening of an integrally molded product composed of the one master mold part and the gasket part. .

[0009]

FIG. 1 shows a first embodiment of a molding die according to the present invention.

The main mold has two master molds (convex master mold 11,
A liquid plastic raw material is injected into a cavity formed by the concave mother die 12) and the molding gasket 1 sandwiched between these, and the plastic raw material is cured in the cavity to mold an optical element. In the present embodiment and each embodiment described later, a plastic lens is taken as an example of the optical element. The convex mother die 11, the concave mother die 12, and the molding gasket 1 are the pressing springs 4.
Have been struck by. As the molding gasket 1 and the pressing spring 4, those conventionally used (see FIG. 5) are used as they are. On the other hand, unlike the conventional case, the convex mother die 11 and the concave mother die 12 are manufactured by injection molding using a synthetic resin. In this embodiment, a monomer is used as the plastic raw material, and the convex mother die 11,
An olefin resin is used for the concave mother die 12.

If a synthetic resin is used as the matrix material, the convex matrix 11 and the concave matrix 12 can be manufactured by injection molding.
By doing so, it is not necessary to perform different processes such as a grinding process, a sanding process, and a polishing process which are conventionally performed, and it becomes possible to produce a large number of mother dies in a short time.

FIG. 2 shows a second embodiment of the molding die according to the present invention.

In the first embodiment, the molding gasket 1
I turn over a part of it and inject the plastic raw material from here, but this work is a little complicated. Therefore, in this embodiment, the injection port 22 for injecting the plastic raw material is formed in the molding gasket 22 to improve workability at the time of injecting the raw material.

FIG. 3 shows a third embodiment of the molding die according to the present invention.

In the figure, the mother die portion 33 and the gasket portion 31 are integrally molded using synthetic resin, and the opening of this integrally molded product is sealed by the mother die portion 34. Mother part 3
By integrally molding 3 and the gasket portion 31, the number of parts can be reduced. The mother die 34 is fixed by the pressing spring 4. Specifically, the mother die part 33 and the gasket part 31 are manufactured by injection molding the above-mentioned olefin resin. An injection port 32 for injecting the plastic raw material is formed in the gasket portion 31. Mother part 3
4 is a glass concave mold 3 that is conventionally used
(See FIG. 5). If one surface of the plastic lens has a complicated aspherical shape such as a progressive focus lens,
Such recycling is useful because the cost of producing the master mold required for forming this surface shape is high. Further, when the surface shape of the molded plastic lens is further adjusted in a later step, it is not necessary to manufacture the cavity formed by the mother die parts 33 and 34 and the gasket part 31 with high accuracy. In such a case, the synthetic resin concave die 12 used in the first embodiment may be used as the die 34 to further reduce the manufacturing cost.

FIG. 4 shows a fourth embodiment of the molding die according to the present invention.

In the figure, the mother die portion 43 and the gasket portion 41 are integrally molded using a synthetic resin as in the third embodiment, and the opening of this integrally molded product is sealed by the mother die portion 44. are doing. The mother die part 44 is a concave mother die 3 made of glass.
(See FIG. 5) or the resin-made concave mold 12 used in the first embodiment. An injection port 42 for injecting a plastic raw material is formed in the gasket portion 41.

In the present embodiment, the gasket portion 41
A fitting groove 45 into which the peripheral portion of the mother die portion 44 is fitted is formed in the. The protrusion 46 located outside the fitting groove 45 is
When the mother die portion 44 is mounted on the gasket portion 41, the mother die portion 44 is elastically deformed and pushed outward, so that the fitting groove 4 of the gasket portion 41 is inserted.
After the peripheral portion of the mother die portion 44 is fitted in 5, the mother die portion 44 returns to its original shape and is fixed.

With this structure, the above-mentioned pressing spring can be omitted.

[0020]

According to the present invention, one or both of the two master mold parts are made of synthetic resin, so that the two master mold parts can be formed in a shorter time than the conventional one. Molding can be produced at low cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of a molding die according to the present invention.

FIG. 2 is a cross-sectional view of a second embodiment of a molding die according to the present invention.

FIG. 3 is a cross-sectional view of a third embodiment of a molding die according to the present invention.

FIG. 4 is a cross-sectional view of a fourth embodiment of the molding die according to the present invention.

FIG. 5 is an explanatory view showing an outline of a conventional casting method.

[Explanation of symbols]

 1, 21 ... Molding gasket, 4 ... Pressing spring, 11 ... Convex mother die, 12 ... Recessed mother die, 22, 42 ... Injection port, 31, 41 ... Gasket Part, 33, 34, 43, 44 ... Mother mold part, 46 ... Elastic protrusion

Claims (5)

[Claims] 1. A liquid plastic raw material is injected into a cavity formed by two mother dies and a molding gasket sandwiched between them, and the plastic raw material is cured in the cavity to mold an optical element. In the molding die, each of the two mother dies is made of synthetic resin. 2. Two gaskets arranged at regular intervals by a gasket portion.
Liquid plastic material is injected between the two mold parts,
In a mold for curing the injected raw material into the shape of an intended optical element, one of the two mold parts and the gasket part are integrally molded using a synthetic resin, A molding die, wherein the other master die portion of the two master die portions seals an opening of an integrally molded product including the one master die portion and the gasket portion. 3. The molding die according to claim 2, wherein the gasket portion is formed with a fitting groove into which the other mother die portion is fitted. 4. The molding die according to claim 2, wherein the gasket portion is provided with an injection port for injecting the liquid plastic raw material. 5. The molding die according to claim 1, 2, 3, or 4, wherein the synthetic resin is an olefin resin.