JPH0671708A - Injection mold for thin molded form - Google Patents

Abstract

PURPOSE:To easily fill rubber or melted resin in a cavity with relatively low pressure by sliding part of a mold corresponding to an injection amount when the rubber or the melted resin is injected from a runner gate into the mold. CONSTITUTION:When rubber or melted resin is injected, a lower mold 2 is moved upward by a hydraulic cylinder 5. The mold 2 is moved down under the guidance of the mold 2 by an upper mold 1 simultaneously upon injection of the rubber or the mold. Thus, the rubber or the resin to be injected is released from resistance of a wall of the mold 2. The rubber or the resin is drawn by a frictional resistance of the mold 2 and fed to the mold 1. At the time of completing the injection, a complete mold is formed, and a molded form of high accuracy can be obtained by vulcanizing or cooling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus for molding a thin product of rubber or molten resin, which requires a high degree of precision that can only be obtained by molding.

[0002]

2. Description of the Related Art As shown in FIG. 3, a cavity formed by a mold is injected at a high pressure through a sprue and a runner. However, when the cavity is thin, the flow is obstructed by the resistance of the mold wall surface, causing scorching and solidification. Due to other reasons, the flow became insufficient and injection molding was not possible with the conventional technology. Therefore, in the case of rubber, it is necessary to perform extrusion molding at the expense of accuracy, or to extrude and vulcanize once and polish the surface to obtain accuracy, and in the case of resin, there is no choice but to ignore accuracy and blow molding. It was

[0003]

SUMMARY OF THE INVENTION In the above conventional technique,
The material is not fully filled due to turbulence and frictional resistance on the mold wall. It is an object of the present invention to solve the above problems and to easily fill a cavity with a rubber or a molten resin at a relatively low pressure.

[0004]

According to the present invention, when rubber or molten resin is injected, a part of a mold forming a cavity moves as necessary to eliminate frictional resistance of a wall surface and at the same time move a metal mold. The frictional resistance of the mold wall is used to supply the material to the fixed mold surface.

[0005]

[Function] Rubber or molten resin is injected from the runner, and injection into the cavity is started. At the same time, a part of the mold having guides that compose the cavity moves according to the injection amount, and the required amount is filled. Form a perfect cavity when played.

[0006]

Since the present invention is constructed as described above, there is no obstruction of the flow due to the wall surface during injection, and it is possible to easily fill the cavity with the rubber or the molten resin.
Therefore, as in the conventional case, it is possible to prevent short shots or burns caused by compression heat, and the guide forms a complete mold cavity at the time of completion of injection, so that a product with high accuracy can be manufactured. I can.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to the drawings. When injecting rubber or molten resin as shown in FIG. 1, the outer die is moved upward by a device such as a hydraulic cylinder, and simultaneously with the injection of rubber or molten resin, the outer die is lowered while being guided by the inner die. The rubber or molten resin injected by this not only eliminates the resistance of the outer mold wall surface, but the friction resistance of the outer mold pulls the rubber or molten resin into the inner mold, and when the injection is completed, it is completely removed as shown in FIG. By forming the mold and vulcanizing or cooling it, a product with high accuracy can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an injection device before molding showing an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the injection device after completion of molding, showing an embodiment of the present invention.

FIG. 3 is a vertical cross-sectional view of a conventional injection device.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Sprue 4 Runner 5 Hydraulic cylinder 6 Cavity (Product part)

Claims (1)

[Claims] 1. When a rubber or a molten resin is poured into a mold from a runner gate made to flow uniformly, a part of the mold slides in accordance with the injection amount to make the injection. By eliminating the turbulent flow on the injection surface and the frictional resistance on the wall that sometimes occur, thin-walled products can be easily molded by preventing the flow deficiency due to rubber scorch or resin solidification, etc. A molding device for rubber or molten resin.