JPH06845A - Injection mold - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a gate system with no gate remaining. [Structure] A pin 2 is provided on the side opposite to the product surface on which the gate is installed, and the tip shape of this pin is an acute angle. [Effect] Since the remaining gate on the cut surface of the gate can be reliably eliminated, there is no need to leave a convex shape on the mold to make a recess for the gate escape, which facilitates mold processing and does not require gate cutting after molding. become. Further, there is an effect that it is possible to prevent a gate disconnection defect that occurs when a large gate diameter is required or when a multi-point gate is used. A gate cut state suitable for various resins and gate dimensions can be obtained simply by adjusting the height of the acute angle pin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate system for a plastic injection mold (hereinafter referred to as a mold).

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional gate method in a mold 10 has a gate relief step H at the installation portion of a gate 11 of a product.

This is to prevent the functional problem and the deterioration of the appearance quality due to the protrusion due to the remaining gate protruding from the product surface F.

[0004]

However, in the conventional gate method, when molding nylon, polyurethane resin or the like, stringing occurs on the cut surface of the gate, so that the size of the convex portion of the gate remains uneven. , It was necessary to increase the step of the gate escape.

When the gate installation surface of the product is thin,
There was a problem that a step could not be made large and gate cutting had to be performed after molding.

In order to solve the above-mentioned conventional problems, the present invention provides a pin on the surface opposite to the gate installation surface of the product to reduce variations in the remaining gates and does not require a large gate relief process. It is an object to provide a gate method that does not require gate cutting.

It is another object of the present invention to provide a gate system which does not require the processing of the gate relief step which has been performed by the conventional gate system.

[0008]

The gate system of the injection molding die of the present invention is characterized in that a pin is provided on the side opposite to the product surface on which the gate is installed, and the tip shape of the pin is an acute angle. Is characterized by.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view showing a gate system of an injection molding die 5 of the present invention. Pins 2 are installed on the side opposite to the installation surface of the gate 1 of the product, and the pins 2 are installed with the gate 1. Move closer to product surface F.

FIG. 2 is an enlarged cross-sectional view of the gate 1, in which the pin 2 is installed to secure the minimum cross-sectional area S on the product installation surface of the gate 1.

Since the injected resin has the thinnest portion in the minimum sectional area S, solidification is rapidly promoted.

In the gate cutting step, when the gate 1 is pulled in the direction of arrow A, a pulling force acts on the minimum cross-sectional area S of the gate 1 and the product and the gate can be cut at the minimum cross-sectional area S.

By forming the minimum cross-section area at the intended cutting point, the solidification of the resin at the gate cutting point is promoted to prevent stringing due to the molten state of the resin and further prevent the variation at the cutting point. .

As shown in FIG. 2, the tip of the pin 2 is formed into an acute angle and the minimum cross-sectional area S portion is provided on the side opposite to the gate of the product surface F of the gate 1 so that the gate can be cut on the product side. As a result, the remaining gate on the product surface can be more surely eliminated, so that it is not necessary to process the mold in a convex shape in order to form the recess for the gate escape in the product, and the mold processing is facilitated.

By making the tip of the pin an acute angle, the pressure loss of the resin at the time of injection can be prevented, and at the same time the diameter of the pin can be increased, so that the strength of the pin can be secured.

Further, the size of the minimum sectional area can be easily adjusted by adjusting the height of the pin. If you increase the gate diameter for reasons such as delaying the gate sealing time due to the need for holding pressure, or if you increase the number of gate points, the gate cross-sectional area will increase and you will be able to cut with just the force pulling the gate during the gate cutting process. Is difficult.

In this case, although the gate system of the present invention can reduce the cross-sectional area of the gate cut surface,
Since the distance of the portion having a small cross-sectional area is short, the pressure loss in the injection process is small, the gate sealing time can be prevented from being shortened, and the effect on the pressure holding effect can be reduced.

The present invention has a simple structure in which only pins are provided, and the die machining cost is low.

In this embodiment, the pin gate is used, but it goes without saying that it can be applied to other gates such as a submarine.

[0021]

According to the gate method of the present invention, it is possible to surely eliminate the remaining gate on the cut surface of the gate. Therefore, it is not necessary to leave a convex shape in the mold to make a recess for the gate escape, and the mold can be processed. This has the effect of facilitating the process and eliminating the need for gate cutting after molding. Further, there is an effect that it is possible to prevent a gate disconnection defect that occurs when a large gate diameter is required or when a multi-point gate is used.

Further, according to the present invention, there is an effect that a gate cut state suitable for various resins and gate dimensions can be obtained only by adjusting the height of a pin having a sharp tip.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a gate system of the present invention.

FIG. 2 is an enlarged cross-sectional view of the gate method of the present invention.

FIG. 3 is a sectional view showing a conventional gate method.

[Explanation of symbols] 1 gate 2 pins

Claims (2)

[Claims] 1. An injection-molding die, wherein a pin having a part of its tip inserted into the gate is provided from the side opposite to the product surface on which the gate is installed. 2. The injection mold according to claim 1, wherein the tip of the pin has an acute angle.