JPS6084723A - Resin molding part with metal insert - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a molded part having a metal insert such as a resin insulator in, for example, heavy electrical equipment.

[Technical background of the invention and its problems]

In order to stabilize the quality of resin molded parts,
It is desired that the filler be uniformly distributed throughout the molded part.

However, in the case of an insulator made of epoxy resin with a metal insert, since the thermal expansion coefficients of the metal and epoxy resin are significantly different, peeling occurs between the insert and the epoxy resin, resulting in poor mechanical strength or There were drawbacks such as deterioration of electrical characteristics. Further, various properties of resin molding materials are significantly improved by adding fillers. Among these, effects such as improving flame resistance, chemical resistance, mechanical strength, electrical properties, and wear resistance are more effective near the surface of the molded part, and the general method of uniformly distributing filler material It cannot be said that the advantages of adding filler are being effectively utilized.

As a method to improve these drawbacks, the quality of molded parts has been improved by combining resins with different characteristics, such as a two-stage casting method. In other words, injecting a resin with low thermal conductivity between the outer resin and metal,
Alternatively, the outer resin is cast as a material with higher strength than the inner resin to improve mechanical properties.

However, this method requires multiple resin materials, and also creates an interface between different types of resin in the resin molded part. Peeling of this part deteriorates the mechanical and electrical properties of the part and reduces product reliability. This results in a decrease in

[Purpose of the invention]

An object of the present invention is to provide a molded part that prevents peeling of the metal insert and resin from occurring due to heat and the occurrence of cracks, and increases the overall strength by improving the properties of the surface of the molded part.

[Summary of the invention]

The present invention relates to a resin molded part having a metal insert, and the concentration of filler in the resin is adjusted such that the filler content is high near the metal insert and near the surface, and the filler content is low in other parts. By providing a continuous slope, the strength against mechanical and electrical stress caused by the difference in thermal expansion coefficient with the metal insert, as well as against heat and chemicals on the surface area, is improved.

Examples of the invention] The present invention will be described in detail below with reference to Examples.

In this example, an epoxy resin is used as the reinforcing resin, but the epoxy resin alone or a commonly used resin composition containing an inorganic filler has a coefficient of thermal expansion of 30 to 50.
xlO/°C, which is extremely large compared to the coefficient of thermal expansion of metals such as mild steel. The epoxy resin used here uses inorganic powder as a filler, and fused quartz with a low coefficient of thermal expansion for the ribs.
Contain 70-80% of it. In this way, the coefficient of thermal expansion of this resin becomes as small as 15 to 30 x 10-'/°C. According to experiments, when the coefficient of thermal expansion is 30×10/'G or less, peeling or cracking from metal becomes less likely to occur.

Naturally, the closer the coefficient of thermal expansion is to that of metal, the more difficult it is to peel off even when subjected to severe cooling and heating cycles. Therefore, the content of fused silica powder in the resin near the metal insert was reduced to 70%.
or more, and the coefficient of thermal expansion is set to be 30 x 10 fG or less.

Additionally, by adding fillers, various properties are improved as shown in the table below. Furthermore, other experiments have shown that flame resistance and chemical resistance are improved. These effects can be further improved by increasing the amount of filler, but if too much is added, for example, the content of fused silica powder will increase to 83
% or more, it will not mix sufficiently with the resin and the viscosity will increase, making casting work difficult. Therefore, the concentration of the filler should be increased near the surface of the molded part and near the metal insert, where the effect of filler injection is greatest, and the concentration of the filler should be lowered in other areas to facilitate the casting process. The idea was to avoid reducing the overall workability.

At that time, as mentioned above, the multi-stage casting method using different resins
This is not preferable because an interface is formed. Therefore,.

The present invention is intended to maximize the effect of the filler by creating a continuous gradient in the concentration of the filler in the resin, as shown in FIG.

Next, a specific example of the configuration will be explained using FIG. 2.

In the insulator 5 as shown in Fig. 2, the filler content is adjusted so that the quartz filler concentration in the vicinity of the screw-fixing embedding fitting 6 that becomes the metal insert and in the outer creeping area is about 75 to 80%. It is created with a slope as shown in Figure 1. In the figure, 9 is a loading jig, 7 is a hexagonal bolt, and 10 is a support frame. After this insulator was subjected to 20 cooling/heating cycles of 1 hour in 0°C water and 1 hour in 100°C water, even when a load W was applied as shown in Fig. 2, the embedded fitting 6 did not peel off or No cracks caused by this were observed. On the other hand, for insulators made under uniform conditions with no filler concentration gradient, about half of the test samples were
Cracks were observed due to decreased adhesion between the embedded metal fittings and the resin. Further, even when no cooling/heating cycle is performed, the products of the present invention have significantly improved properties such as dielectric strength, bending strength, chemical resistance, flame resistance, and abrasion resistance.

[Effects of the Invention] As described above, according to the present invention, the properties can be improved by adding a filler to 111% without reducing the overall workability.
The mechanical and electrical strength is greatly improved without causing cracks due to heat.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the distribution of the filler content in the resin between the metal insert and the surface of the resin molded part according to the present invention, and FIG. It is a figure showing one example of parts. 5... Insulator 6... Embedded metal fitting 7... Hexagonal bolt 8... Load 9... Loading jig 10... Supporting frame (73
17) Agent Patent attorney Kensuke Chika (and 1 other person) Figure 1

Claims (1)

[Claims] In a resin molded part having a metal insert, there is a continuous gradient in the concentration of the filler in the resin such that the filler content is high near the metal insert and near the surface, and the filler content is low in other parts. A resin molded part with a metal insert.