JPH0232603A - Manufacture of reflecting mirror for parabolic antenna - Google Patents

Abstract

PURPOSE:To improve productivity and quality by employing a system in which a conductive coating material is applied on a metal mold and it is transferred at the time of injecting resin. CONSTITUTION:The conductive coating material is applied on the metal mold 11 that is the inner plane side of a reflecting mirror in advance with spray coating, etc. The metal mold is set after hardening the conductive coating material, and it is hardened by injecting polyurethane resin in the cavity part of the metal mold. A conductive coating layer is transferred on the inner plane when a molded product is taken out after the resin is hardened. An enamel coating material as a coating material with weatherability is applied on the entire plane of the molded product on which the conductive layer is transferred. In such a way, it is possible to obtain superior workability and to lower a fraction defective remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a reflecting mirror, which is a main component of a parabolic antenna of a satellite broadcast receiving system.

[Conventional technology]

Conventional VHF broadcasting is around 100MHz, so the wavelength is 3.
In contrast, satellite broadcasting uses a high frequency of the 12 GHz band, so the wavelength is only 2.5 cm (conventional Yagi antennas cannot receive satellite broadcasts).

Therefore, satellite broadcasting can be received by using a parabolic antenna that provides high gain. This parabolic antenna has the shape of a paraboloid of revolution, and is designed to concentrate and reflect radio waves at its focal point by pointing toward the broadcasting satellite. Generally, an offset parabolic antenna is used, which uses a part of a large paraboloid of revolution. The advantage of this method is that the primary radiator can be set around the reflector, and the reflector can be designed to be smaller accordingly.

Conventionally, there are the following methods for manufacturing a reflecting mirror for a parabolic antenna for this purpose.

First, a base body of a reflecting mirror having a paraboloid of revolution is created by a method such as injection molding. At this time, the resin used is FRP. Next, a metal foil or mesh made of aluminum or the like is cut and pasted along the inner surface of the reflector. Finally, apply weather-resistant paint to the entire interior and exterior surfaces.

In this case, in the process of cutting and pasting the metal foil or metal mesh, since the reflecting mirror is not made of a paraboloid of revolution, the metal foil or metal mesh must be cut and pasted by hand, resulting in extremely poor productivity. ing. Moreover, if the paste fails and wrinkles occur, the reality is that the reflector itself is disposed of as it cannot be repaired. For the above reasons, the production cost of parabolic antennas is extremely high.

Other manufacturing methods include 1. A method of deep drawing pressing a metal plate such as aluminum; 2. There is a method of setting metal foil, metal mesh, or metal woven fabric in the mold when injection molding resin, but the former cannot produce large diameter items due to cost issues, and the latter requires that the foil etc. be pressed. It may be disconnected at times.

[Problem that the invention seeks to solve]

The present invention was developed as a result of research into a method that improves workability and dramatically reduces the defective rate during the manufacturing of reflective mirrors.
It is completed.

[Means for Solving the Problems] The present invention has the following features: (1) In a method for manufacturing a reflecting mirror for a parabolic antenna, a mold corresponding to the inner surface is coated with a conductive paint and then dried, and then a polyurethane resin is coated with the gold. By injecting it into a mold and solidifying it, the conductive paint layer is simultaneously transferred to the inner surface of the resin layer to create a paraboloid-shaped molded product with a conductive paint layer on the inner surface, and then coated with weather-resistant paint. A method for manufacturing a reflector for a parabolic antenna, characterized by:

■In the method of manufacturing a reflector for a parabolic antenna, the mold corresponding to the inner surface is first coated with a weather-resistant paint and dried, then a conductive paint is coated and dried.
By injecting polyurethane resin into a mold and solidifying it, a weather-resistant paint layer and a conductive paint layer are simultaneously transferred to the inner surface of the resin layer. This is a method for manufacturing a reflecting mirror for a parabolic antenna, which is characterized by creating a molded product in the shape of an object surface.

[Function] The conductive paint as referred to in the present invention is a resin-based paint containing metal powder or carbon powder as a filler, and can be applied with a spray gun or with a brush. In this case, suitable metal powders are Ag powder, Cu powder, and Ni powder.

The resin may be acrylic, urethane, epoxy, phenol, etc., but must be able to withstand the temperature during injection of the urethane resin.

However, since the resin constituting the base is a polyurethane resin, a urethane-based paint is suitable to improve adhesion, and copper powder is suitable as a filler from the viewpoint of cost and performance.

The polyurethane resin referred to in the present invention is preferably a two-component curing type. In this case, the curing reaction is completed within 1 to 10 minutes after injecting the resin into the mold, so there is no need to inject the resin at high temperature and pressure as in normal injection molding, and relatively simple equipment is required.
Cheap molds can also be used.

〔Example〕

A method for manufacturing a reflecting mirror using the present invention will be explained with reference to the drawings. First, a conductive paint is applied in advance to the mold 11 corresponding to the inner surface of the reflecting mirror by spray painting or the like (Fig. 1). In this case, the film thickness may be 10 to 30 μm. Also, it is better to apply a mold release agent to the mold before applying the conductive paint. After the conductive paint has hardened, a mold is set, and polyurethane resin is injected into the cavity of the mold and allowed to harden (Figure 2). When the molded product is taken out after the resin has hardened, a conductive paint layer has been transferred to the inner surface. The surface of this conductive paint layer was smooth, and the adhesion between the conductive layer and the substrate (molded article) was also good. Enamel paint was applied as a weather-resistant paint to a film thickness of 11 over the entire surface of the molded article onto which the conductive layer had been transferred. (3rd
figure).

A parabolic antenna is completed by installing the primary reflector 23 and the BS converter 24 at the focal point of the reflector manufactured by the above method. (Figure 4).

By painting the mold with a weather-resistant paint before applying the conductive paint to the mold, it is possible to transfer the conductive paint layer and the weather-resistant paint to the valve opening when resin is injected, and the final painting process is completed. It is possible to simplify.

〔Effect of the invention〕

In the conventional method, metal foil or metal mesh was cut and pasted by hand, resulting in poor productivity and a high defect rate. In contrast, the present invention employs a method in which a conductive paint is applied to the mold in advance and transferred during resin injection, thereby significantly improving productivity and quality. In other words, in the method of the present invention, the radio wave reflecting surface is a replica of the surface of the mold, and if a flat foil was manually attached to a curved surface as in the conventional method, the surface would be uneven due to skill level. However, the dimensional accuracy and surface roughness are dramatically improved. Therefore, the reception characteristics are also improved.

As described above, the present invention greatly contributes to improving productivity and quality when manufacturing a reflecting mirror for a parabolic antenna.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are schematic diagrams each showing an embodiment of the present invention. FIG. 4 is an overall view of the parabolic antenna. 11.12 Mold 21 Resin injection port 22 Reflector 23 -
Next reflector 24BS converter 31 Conductive paint 3
2 Weather-resistant paint

Claims (2)

[Claims] (1) In the method of manufacturing a reflector for a parabolic antenna, a conductive paint is applied to a mold corresponding to the inner surface and dried, and then a polyurethane resin is injected into the mold and solidified, and at the same time a conductive paint layer is applied. Manufacture of a reflector for a parabolic antenna, characterized in that a paraboloid-shaped molded product having a conductive paint layer on the inner surface is created by transferring it to the inner surface of a resin layer, and then coated with a weather-resistant paint. Method. (2) In the method of manufacturing a reflector for a parabolic antenna, the mold corresponding to the inner surface is first coated with a weather-resistant paint and dried, then a conductive paint is coated and dried, and then a polyurethane resin is applied. By injecting into the mold and solidifying, the weather-resistant paint layer and conductive paint layer are transferred to the inner surface of the resin layer, thereby creating a paraboloid of revolution shape with a conductive paint layer and a weather-resistant paint layer on the inner surface. A method for manufacturing a reflector for a parabolic antenna, the method comprising: producing a molded product.