JPH0939033A - Injection molding method having secondary injection mechanism at gate part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate after-processing in injection molding of rubber resin by removing waste of material for a sprue, a runner, and a gate to achieve ultimate rationalization for a yield. SOLUTION: In a injection molding of rubber resin, a gate 5 leading to a cavity 6 from a hot or cold runner 4 is constituted in a cylindrical shape. A hydraulically driven small piston 8 is provided therein. Material in the gate part 5 is sent into the cavity 6 to complete injection. Besides, a surface of a product is formed by an end surface of the small piston 8, and the runner 4 is held by blocking with a side surface. Thereby, a 100% yield can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber or resin mold structure and an injection molding apparatus.

[0002]

2. Description of the Related Art As shown in FIG. 2, a cavity (6) formed in a mold (1) (2) is injected at high pressure from a nozzle (7) through a sprue (3), a runner (4) and a gate (5). However, the material of the sprue / runner / gate portion is vulcanized or cooled together with the product, taken out, and then recycled or discarded. Although some improvements have been made in hot runners and cold runners, 100% of the materials have not been used.

[0003]

An object of the present invention is to utilize 100% of the material and to eliminate post-processing such as gate cutting which could not be achieved by the above-mentioned conventional techniques.

[0004]

[Means for Solving the Problems] A product gate is made into a cylinder and equipped with a piston that slides in the cylinder, and a material is injected from one end of the cylinder into the cylinder and the product portion from a cold or hot runner (primary injection). When the injection of the set volume is completed, the cylinder connected to the piston that slides in the cylinder operates and the piston presses the material in the cylinder into the cavity (secondary injection) and closes the gate at the same time when the molding is completed. . At this time, the product surface of the piston has a configuration that forms the product.

[0005]

Operation: The material of the capacity set by the injection function of the existing injection molding machine is injected into the cavity through the cylindrical gate equipped with the piston, and then the piston is advanced to completely fill the cavity and the gate disappears. The tips of shape the product.

[0006]

Since the present invention is constructed as described above,
It is possible to improve the yield up to 100% by pressing the gate part into the product part, which was left and discarded in the conventional molding method, and the final molding pressure is easy because it is done with a piston of a few millimeters or less. It is possible to obtain a high pressure
It is possible to save energy and simplify the injection unit as a whole.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. On the left side of the center line in FIG. 1, the small piston (8) is connected to the hydraulic cylinder (1
0) pulls it upward to form a gate (5) and links the runner (4) and the sprue (3). A certain amount of material injected from the nozzle (7) is injected into the cavity (6) through the sprue runner gate. (Primary injection) Then, on the right side of the center line, the material of the gate is pressed into the cavity by operating the hydraulic cylinder downward, and at the same time the small piston closes the gate and the end forms the product surface. Then the injection is completed. (Secondary injection) In this case, the mold part containing the sprue runner is cold runner for rubber and hot for resin.
By adopting a runner structure, the material in this part can be used as the next molding material, so that a yield of 100% can be achieved. At the same time, the gate part is eliminated, and post-processing such as gate cutting is also unnecessary, and ultimate rationalization can be achieved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a mold and an accessory device showing an embodiment of the present invention, in which a left side of a center line shows a state where primary injection is completed, and a right side shows a state where secondary injection is completed.

[Explanation of symbols]

1 Upper Mold 2 Lower Mold 3 Sprue 4 Runner 5 Gate 6 Cavity 7 Nozzle 8 Small Piston 9 Bracket 10 Hydraulic Cylinder 11 Insulation Board 12 Hot or Cold Runner Structure Part Constituting Sprue Runner 13 Block for Mold Holding 14 Molding Machine Fixed plate

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[Procedure amendment]

[Submission date] December 14, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Added

[Correction contents]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a mold and an accessory device showing an embodiment of the present invention, in which the left side of the center line is the primary injection and the right side is the second.
The state where the next injection is completed is shown.

FIG. 2 is a vertical sectional view of a conventional mold structure for injection molding rubber or molten resin.

[Explanation of symbols] 1 Upper mold 2 Lower mold 3 Sprue 4 Runner 5 Gate 6 Cavity 7 Nozzle 8 Small piston 9 Bracket 10 Hydraulic cylinder 11 Insulation board 12 Hot or cold runner structure that constitutes the sprue runner 13 To hold the mold Block 14 Fixed plate of molding machine

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

[Fig. 2]

Claims (1)

[Claims] 1. When rubber or molten resin is injection molded,
Generally, the material is injected into the cavity through the sprue runner gate in the mold, but a small cylinder that constitutes the gate is interposed between the runner and the molded product, and injection molding is performed in two stages. Control to eliminate post-processing such as gate cutting, while using a cold runner for rubber molding and a hot runner for resin molding.
A rubber or resin mold structure and a molding apparatus, which eliminates waste of materials due to runners and gates and achieves a molding yield of 100%.