JPH0639880A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To provide a mold for injection molding having excellent dimensional accuracy, wherein gate cutting and a product take-out are easily, performed after molding and being useful for molding a molded item with a hole shape such as a ring. CONSTITUTION:A disc gate 2 corresponding to a hole shape is formed by a divisional type fixed part A and a mold pun and the mold pin consists of a fixed pin 3 and a movable sleeve pin 4 around it and gate cutting is done by the sleeve pin 4 and taking a product out and exclusion of a sprue are performed thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold. More specifically, the present invention provides a new metal useful for molding an injection-molded product having a hole shape such as a ring-shaped molded product, which has improved dimensional accuracy and can facilitate gate cutting and product removal after molding. It is about the type.

[0002]

2. Description of the Related Art Conventionally, a method for injection molding of various shapes and a mold and a mold used therefor have been devised and improved, and a product formed by this injection molding has a ring shape, a pipe shape, or the like. Shaped articles are also known. For molding of molded products with these hole shapes,
For example, as shown in FIG. 3, in order to mold a ring-shaped molded product (A), a normal means in injection molding such as resin injection from a side gate (A) or injection from a pinpoint gate (C). The gate forming method is adopted, and a mold equipped with a knockout pin or the like for that purpose is used.

[0003]

However, in the case of the method and the die using the resin material injection method by the conventional side gate method and pinpoint gate method,
The orientation of the inorganic fiber such as glass or the organic fiber has a great influence on the quality of the molded product, and the roundness of the hole-shaped product, especially the ring-shaped product tends to be reduced.

Therefore, such a conventional method is not preferable for product quality. Also, as in the past, in the case of molded products taken out of the mold with sprue and runner attached, the area near the gate tends to become smaller due to heat shrinkage, and the dimensions such as cylindricity are greatly affected. , The dimensional accuracy did not improve.

Therefore, in order to manufacture a molded product such as a hole-shaped, particularly a circular ring-shaped body or a pipe-shaped body by injection molding, it is possible to replace the conventional method with a better dimensional accuracy and also to have the structure. It has been desired to establish a simple mold and an injection molding method using the mold. The present invention has been made in view of the above circumstances, and provides a new injection molding die that solves the drawbacks of the conventional method, has excellent dimensional accuracy, and is easy and easy for gate cutting, product removal, and the like. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems by providing a mold for injection molding of a hole-shaped molded product, in which the fixing portion of the split mold and the mold pin have a hole shape. To provide an injection molding die characterized in that a corresponding disc gate is formed, a die pin is composed of a fixed pin and a movable sleeve pin around its periphery, and gate cutting is performed by the sleeve pin to perform product removal and sprue elimination. .

[0007]

In the mold of the present invention, the disc gate system which is completely different from the conventional system is adopted.
The orientation appears in the circumferential direction, and the roundness of the molded product is greatly improved. Moreover, since the disk gate is gate-cut by the movable sleeve pin around the fixed pin without using a knockout pin as in the conventional case, the gate is easily cut even if the pressure is small, and the molded product is clean. Since the sprue is removed when the product is taken out, there is no deterioration in cylindricity due to the difference in shrinkage, and post-finishing is easy.

Of course, the packing density in the molded product is also improved by adopting the disk gate, and the strength is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the accompanying drawings showing embodiments. FIG. 1 exemplifies an injection mold of the present invention, which is intended for molding a ring-shaped molded product (1).

As shown in FIG. 1, in this mold, the disk gate (2) is formed by fixing the fixed part (A) of the split molds (A) and (B) and the metal in the mold (B) facing the fixed part (A). It is formed by a mold pin. The mold pin in this case is composed of a fixed pin (3) and a movable sleeve pin (4) around its periphery. Of these, the movable sleeve pin (4) operates separately from the fixed pin (3) and gate-cuts the disc gate (2) after resin injection. In the case of FIG. 1, the sleeve pin (4) is moved upward to perform gate cutting, and further moved to take out the molded product (1) from the mold. At this time, the sprue (5) is also excluded from the mold.

FIG. 2 illustrates the ring-shaped molded product (1) taken out from the molds (A) and (B) and the sprue (5) removed from the mold. The entire circumference of the disc-shaped portion at the tip of the sprue (5) formed the disc gate (2). For example, in the mold of the present invention having the above-described configuration, the shape, size, and movement of the sleeve pin (4) are determined according to the shape and size of the molded product that is a product.

Of course, the present invention is not limited to the above examples, and various details can be made.

[0013]

As described in detail above, in the injection molding die of the present invention, since the knockout pin is not used as in the conventional case, the surface of the molded product is clean and the disc gate (2) has the sleeve pin ( Since it is cut according to 4), even if the pressure is small, the gate is cut well.

Since the resin is injected by the disc gate (2), as is clear from FIGS. 1 and 2, the orientation appears in the circumferential direction and the roundness is good. Further, since the gate is cut, the cylindricity does not deteriorate due to the difference in shrinkage as in the conventional case, and the post-finishing is easy. of course,
Since the packing density of the molded product is improved, the strength is improved.

The mold structure is simple and its operation is easy. A mold useful for various thermosetting moldings is provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a mold of the present invention.

FIG. 2 is a perspective view illustrating a molded product and a sprue.

3A and 3B are cross-sectional views showing a conventional gate method.

[Explanation of symbols]

 1 Ring-shaped molded product 2 Disc gate 3 Fixed pin 4 Sleeve pin 5 Sprue

Claims (2)

[Claims] 1. A mold for injection molding of a hole-shaped molded product, wherein a fixed part of the split mold and a mold pin form a disk gate corresponding to the hole shape, and the mold pin is the fixed pin and its peripheral part. The injection molding die is characterized by consisting of a movable sleeve pin, a gate cut by the sleeve pin, and product removal and sprue removal. 2. The injection molding die according to claim 1, wherein the hole-shaped molded product is a molded product of a ring-shaped body or a pipe-shaped body.