JPS61131837A - Manufacturing method of forming mold - Google Patents

Abstract

PURPOSE:To make a forming mold excellent in surface accuracy securable inexpensively, by cutting a forming surface of the forming mold in a state of having heated the forming mold to the extent of temperature in a molding material requiring its hardening by pressure and heating. CONSTITUTION:A heater 4 is installed at the side opposite to a forming surface 3 of a forming mold 1. With this heater 4, the forming mold 1 is heated to the extent of hardening temperature in an FRP material used as a surface material for a parabola reflector. With this heating, the forming mold 1 is expanded to some extent whereby the forming surface 3 is cut in this expanded state. When cutting of the forming surface 3 is over, heating by the heater 4 is stopped. Accordingly, such a forming surface becoming an ideal parabola surface under the hardening temperature of the FRP materail is easily formed up. In addition, even in the case where the parabola reflector is formed with the forming mold 1, the forming surface of the forming mold 1 is cut into highly surface accuracy in a state of being thermally expanded in a manner conformable to the hardening temperature so that the FRP material may copy a curved surface in excellent surface accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention particularly relates to a method for manufacturing molds for articles that are lightweight and require high surface precision, such as articles mounted on satellites.

[Prior art and its problems]

For example, parabolic reflectors used for satellite-mounted items are required to have the necessary strength and rigidity as well as be lightweight. A sandwich plate structure using materials such as wood is often used.

The FRP (fiber-reinforced plastic) material used here must be a high-temperature curing material in order to satisfy the harsh temperature conditions in the space environment, especially heat resistance.

Therefore, as shown in Fig. 2, the uncured FRP material 2 is placed on top of the mold 1, and the FR is molded by applying pressure and heating.
The P material is cured and the curved surface of the mold l is copied.

On the other hand, especially in parabolic reflecting mirrors and the like that transmit and receive in high frequency bands such as the sub-millimeter wave band, high surface precision is required of the reflecting mirror surface due to electrical characteristics.

Therefore, the mold for this type of parabolic reflecting mirror requires particularly high surface precision.

However, when molding a high temperature curing type FRP material, the mold is also exposed to the curing temperature of the FRP material, and during curing, the mold expands thermally and deforms.

Therefore, if the mold is cured in a deformed state, the FRP material will also be formed with a curved surface different from the ideal parabolic surface, and as a result, the requirements for high surface accuracy may not be satisfied.

Conventional manufacturing methods for avoiding such deformation of the molding surface due to thermal expansion include a method of using a material with a particularly low coefficient of thermal expansion, such as Invar, CFRP, special ceramic, etc., for the mold material.

However, since this type of material has a low thermal conductivity, the temperature distribution tends to vary during molding, and the FRP material to be molded is likely to be distorted. In addition, this type of material has poor machinability,
It takes a lot of man-hours to obtain a highly accurate curved surface, and the materials themselves are also very expensive.

Other manufacturing methods include cutting the curved surface by considering thermal expansion at the curing temperature, regardless of the material used for the mold. In other words, this is a method of calculating the curved surface in a state of thermal expansion at high temperature and manufacturing the curved surface in that state.

However, in this case, the shape of the molded surface is a complicated curved surface different from a simple parabolic surface, so that its manufacture, inspection, etc. are complicated. Furthermore, the work of calculating a curved surface in a state of thermal expansion is complicated and prone to errors.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a method of manufacturing a mold for easily and inexpensively realizing a highly accurate reflective mirror surface.

[Structure of the invention]

The present invention is a method for manufacturing a mold for an article using a material that requires curing by pressure and heat, characterized by cutting the molding surface while the mold is at the curing temperature of the material. It is said that

〔Example〕

FIG. 1 is a diagram for explaining a method of manufacturing a mold for a parabolic reflecting mirror according to an embodiment of the present invention.

A heater 4 is provided on the side of the mold 1 opposite to the molding surface 3. This heater heats the mold 1 to the curing temperature of, for example, an FRP material used as a surface material of a parabolic reflecting mirror. This heating causes the mold 1 to expand, and the molding surface 3 is cut in the expanded state. When cutting of the forming surface 3 is completed, heating by the heater 4 is stopped.

By doing so, it is possible to easily form a molding surface that becomes an ideal parabolic surface with a high degree of area at the curing temperature of the FRP material.

When molding a parabolic reflector using the mold 1 obtained as described above, a high temperature curing type FRP material (not shown) is placed on the molding surface 3 of the mold 1 and pressurized. The FRP material is hardened by heating. At this time, the mold 1 is exposed to the curing temperature of the FRP material and thermally expands.

Since the molding die 1 has a molding surface cut with high surface precision while being thermally expanded to this curing temperature, the FRP material can copy curved surfaces with high surface precision.

According to this embodiment, there is no need to be particular about the coefficient of thermal expansion of the material of the mold 1, so it is possible to use a commonly used material such as aluminum, which is inexpensive, has good machinability, and has good thermal conductivity. can. In this case, it is possible to obtain a high-area reflector with less variation in the temperature distribution of the mold at the curing temperature and less distortion during molding.

In addition, the shape of the molding surface can be easily manufactured as a simple parabolic surface shape is sufficient during cutting.

From the above, according to this embodiment, it is possible to easily manufacture a mold for a parabolic reflecting mirror with high surface accuracy.

On the other hand, the heater installed inside the mold is used for FRP during molding.
It can be used as is to bring the material up to the curing temperature, making heating during molding easier.

Although the method for manufacturing a mold for a parabolic reflector has been described above, the present invention is not limited to the mold for a parabolic reflector, and can be generally applied to a method for manufacturing molds for articles that require high surface accuracy. it is obvious.

Further, the heating of the mold is not limited to the heater provided inside, and any means that can heat the mold may be used.

〔Effect of the invention〕

As explained above, according to the present invention, cutting of the molding surface of the mold is carried out while the mold is heated to the temperature of the molding material that requires curing by pressure and heating. It becomes possible to easily and inexpensively obtain a mold with surface accuracy.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a mold for explaining an embodiment of the present invention, and FIG. 2 is a diagram for explaining a conventional method for manufacturing a mold. 1...Molding mold 2...FRP material 3...Molding surface 4...Heater Fig. 2

Claims (1)

[Claims] (1) A method for manufacturing a mold for an article using a material that requires curing by pressure or heat, characterized by cutting the molding surface while the mold is at the curing temperature of the material. A method for manufacturing a mold.