JPH07195448A - Mold assembly for injection molding - Google Patents

Abstract

PURPOSE:To prevent wear of a cavity and occurrence of a flash by a method wherein in a guide hole holding a cylinder part on the top of a core pin forming a hollow of a molded article, a guide member with a conical hole to be filled with a top conical part of the core-pin-top guide cylinder part is slidably provided. CONSTITUTION:In a mold 1, a guide hole 3 to which a core pin is guided to be positioned is so provided as to be connected to a cavity 2. On the top of the guide hole, a member 4 with a conical recess 4a is so disposed as to be slid by being urged by a resilient member 5. In the cavity 2, a core pin 7 for forming a hollow in a molded article is slidably disposed. In the vicinity of the top of the core pin 7, a guide cylinder part 8 to be fitted into the guide hole 3 is formed. The top of the guide cylinder part 8 is formed into a conical part 9 for the easy insertion thereof into the conical recess 4a of the guide member 4. In the process of closing the mold, the conical part 9 is fitted into the conical recess 4a upon completion of positioning the core pin 7. Furthermore, the guide cylinder part 8 is fitted into the guide hole 3, whereby the core pin 7 is completely positioned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cavity in which a molded product is molded, a core pin for forming a cavity in the molded product, and a guide hole for positioning the core pin. The present invention relates to a mold device.

[0002]

2. Description of the Related Art An example of a conventional mold apparatus for injection molding is shown in FIG.
And will be described below. Inside the die 101, a cavity 102 is formed in which the resin flows and the molded product A is molded. A guide hole 103 for guiding and positioning a core pin, which will be described later, is formed in the mold 101 so as to be continuous with the cavity 102. On the other hand, the cavities 102
A core pin 104 that forms a hollow portion in the molded product A is slidably arranged therein. A guide tube 105 fitted into the guide hole 103 is provided near the tip of the core pin 104.
Is formed, and the tip of the guide cylinder 105 is formed in a conical (part) shape 106 so as to be easily fitted.

Next, the operation will be described. When the molding is completed and the mold 101 is closed, the core pin 104 enters the cavity 102. When the closing operation of the die 101 further progresses, the guide cylinder 105 of the core pin 104 moves into the guide hole 103.
And the positioning of the core pin 104 is started. Then, the positioning of the core pin 104 is completed near the middle portion where the mold 101 is completely closed.

[0004]

By the way, the core pin 1
When the core pin 104 is positioned by the guide hole 103, the tip 105a of the guide cylinder 105 is first displaced from the guide hole 1 when the core pin 104 is positioned by the guide hole 103.
03 abuts on the end bottom surface 103a. Such a phenomenon is particularly remarkable in a mold for molding a thin and long shaft such as a writing instrument. Therefore, when the injection molding is repeated by the above operation, the tip portion 105a of the guide tube portion 105 and the guide hole 1 are formed.
The bottom surface 103a of 03 is worn. Due to these wear phenomena, especially due to the wear phenomenon of the bottom surface 103a of the guide hole 103, the resin also enters the worn part, and the molded product A having the burrs a is formed as shown in FIG. Further, these molded products have a problem that not only the value as a product is reduced, but also it takes time and effort to fix them.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a core pin tip guide tube portion is provided in a guide hole for holding a core pin tip guide tube portion forming a cavity of a molded product. A first feature is that a guide member having a conical hole into which a tip conical portion is fitted is slidably arranged, and a guide hole rear end surface that holds a core pin tip guide cylinder portion that forms a cavity of a molded product is provided. A second feature is that a second guide hole, which is larger than the guide hole and smaller than the cavity, is formed between the tip end surface of the cavity and the cavity.

[0006]

1 and 2 show a first embodiment of the present invention. Inside the mold 1, a cavity 2 is formed in which the resin flows and the molded product A is molded. A guide hole 3 for guiding and positioning a core pin, which will be described later, is formed in the mold 1 so as to be continuous with the cavity 2. In the guide hole 3, a guide member 4 having a conical recess 4a formed at its tip is slidably arranged by being biased by an elastic member 5 such as a spring. Reference numeral 6 is a prevention protrusion for preventing the guide member 4 from falling out of the guide hole 3. On the other hand, inside the cavity 2, a core pin 7 forming a hollow portion in the molded product A is slidably arranged. A guide tube portion 8 to be fitted into the guide hole 3 is formed near the tip of the core pin 7, and the tip of the guide tube portion 8 is conical so that it can be easily fitted into the conical recess 4 a of the guide member 4. It is formed in a (part) shape 9.

Next, the operation will be described. At the time of injection molding, the conical portion 9 at the tip of the guide tubular portion 8 abuts and fits into the conical concave portion 4a of the guide member 4 in the process of closing the mold. In this state, the positioning of the core pin 7 is completed. Further, when the mold is closed, the guide member 4 retracts against the elastic member 5 (see FIG. 2), the guide tube portion 8 is fitted into the guide hole 3, and the core pin 7 is completely positioned. At this time, since the positioning of the core pin 7 is performed in advance, the guide tube portion 8
The tip 8a of the guide does not come into contact with the end bottom surface 3a of the guide hole 3. In other words, with the core pin 7 positioned,
The guide tube portion 8 is fitted into the guide hole 3.

3 to 5 show a second embodiment of the present invention. As in the case of the first embodiment, a cavity 2 is formed inside the mold 1 in which a resin flows and a molded product A is molded. A guide hole 3 for guiding and positioning a core pin, which will be described later, is formed in the mold 1 so as to be separated from the cavity 2. The guide hole 3 and the cavity 2 are connected by a conical hole 10 which is a second guide hole formed in the same shape as the outer shape of the core pin. On the other hand, in the cavity 2, a core pin 7 that forms a hollow portion (cylindrical molded product A) in the molded product A is slidably arranged. A guide tube portion 8 to be fitted into the guide hole 3 is formed near the tip of the core pin 7, and the tip of the guide tube portion 8 is formed into a conical (part) shape 9 so as to be easily fitted into the guide hole 3. Is formed in.

Next, the operation will be described. At the time of injection molding, the conical portion 9 at the tip of the guide tube portion 8 comes into contact with the bottom surface 3a of the end portion of the guide hole 3 in the process of closing the mold. When the die is further closed, the eccentricity of the core pin 7 is corrected by the guide hole 3, and the guide tube portion 8 is fitted into the guide hole 3 to position the core pin 7 (see FIG. 4). In this state, the core pin 7 is fitted until it is located in the conical hole 10. At this time, since the core pin 7 is preliminarily positioned, the tip 7a of the core pin 7 does not come into contact with the end bottom surface 10a of the conical hole 10. That is, the core pin 7 is fitted into the conical hole 10 with the core pin 7 positioned (see FIG. 5).

[0010]

According to the present invention, there is provided a guide member having a conical hole into which a tip conical portion of a core pin tip guide cylinder is fitted in a guide hole for holding a core pin tip guide cylinder forming a cavity of a molded product. A second guide which is slidably arranged and which is larger than the guide hole and smaller than the cavity between the rear end face of the guide hole and the front end face of the cavity for holding the core pin tip guide tubular portion forming the cavity of the molded product. Since the holes are formed, the cavities are not worn, so that a molded product (product) of excellent value in which burrs are not formed can be molded.

[Brief description of drawings]

FIG. 1 is a front sectional view of a main part before mounting a core pin according to a first embodiment of the present invention.

FIG. 2 is a diagram when the core pin mounting of FIG. 1 is completed.

FIG. 3 is a front sectional view of a main part before mounting a core pin according to a second embodiment of the present invention.

FIG. 4 is a diagram when the core pin of FIG. 3 is further advanced.

5 is a diagram when the core pin mounting of FIG. 4 is completed.

FIG. 6 is a front sectional view of a main part of a conventional device.

FIG. 7 is a front cross-sectional view of a molded product by a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Cavity 3 Guide hole 4 Guide member 4a Conical recessed part 7 Core pin 8 Guide cylinder part 9 Conical part at the tip of guide cylinder part 10 Conical hole

Claims (2)

[Claims] 1. A guide member having a conical hole into which a conical tip of a core pin tip guide cylinder is fitted, is slidable in a guide hole that holds a core pin tip guide cylinder that forms a cavity of a molded product. A mold device for injection molding, which is characterized by being provided. 2. A second guide hole, which is larger than the guide hole and smaller than the cavity, is formed between the rear end surface of the guide hole for holding the core pin tip guide cylinder forming the cavity of the molded product and the tip end surface of the cavity. A mold device for injection molding characterized by: