JPH07144346A - Injection mold - Google Patents

Abstract

PURPOSE:To provide an injection mold reduced in the production cost, eliminating trouble such as the scoring of the mold and capable of easily performing the correction processing of the quantity of a boss part. CONSTITUTION:In an injection mold, a cavity molding the boss 12 provided to a molded product 1 in a protruding state is formed by the cylindrical core 4 fitted in a movable mold 3 and the core 4 is fitted so that the leading end part thereof penetrates into the cavity partially. A sleeve core pin 5 for forming the boss hole 14 of the boss 12 is inserted in the core 4 up to the almost leading end thereof and the sleeve pin 7 thrusting out the boss 12 is inserted in the core 4 so as to be slidable along the inner surface of the core 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold for a plastic molded product having a boss portion.

[0002]

2. Description of the Related Art Conventionally, in an injection molding die for a plastic molded article having a boss, in order to prevent sink marks from being generated on the surface of the molded article on the back surface of the boss, a meat thin portion is provided on the rising outer peripheral portion of the boss. A mold having a movable mold is adopted. In order to form this meat-thinned portion, so-called leaving processing is performed in which the convex portion which becomes the meat-thinned portion is left in the movable die during the die processing.

The injection molding die will be described below with reference to the drawings. FIG. 2 is a sectional view showing an example of a conventional mold provided with a boss portion. In FIG. 2, reference numeral 10 denotes a molded product. The molded product 10 is provided with a boss 101 protruding from the boss 101.
2 is formed. Reference numeral 20 denotes a movable die, and a convex portion 2 is provided at an upper end portion forming an outer peripheral portion of the boss 101 of the movable die 20.
01 is provided. Reference numeral 30 is a sleeve pin for protruding the boss 101, and 40 is a sleeve core pin for forming a boss hole of the boss 101.

A convex portion 201 provided on the movable die 20.
Since it is formed integrally with the movable die 20, so-called leaving processing is performed, which is left during the die processing as described above.

[0005]

However, the movable injection molding die structure as described above has various problems as described below. 1) It takes a lot of man-hours for die manufacturing. 2) When the moving die is not hardened by heat treatment or the like, a galling phenomenon occurs with the sleeve pin. 3) In the case of insufficient meat stealing, there is no choice but to perform welding by overlaying with welding to affect the strength and durability of the mold.

The present invention has been made by paying attention to the above-mentioned problems, and solves these problems, reduces the manufacturing cost of the mold, and eliminates the trouble such as galling of the mold. Further, the present invention provides an injection molding die structure capable of easily performing correction processing of the amount of thinned meat at the boss portion.

[0007]

In the injection molding die structure of the present invention, a cavity for molding a boss projectingly provided on a molded product is formed by a cylindrical nest fitted in a movable mold, and A sleeve core pin for forming a boss hole at the center of the boss is fitted into the cavity so that the tip of the nest forms a part of the inside of the cavity on the side forming the back surface of the molded product of the cavity. A cylindrical sleeve pin that is formed so as to penetrate almost to the tip position and that forms the upper end surface of the boss and projects the boss portion is inserted between the inner cylinder surface of the insert and the sleeve core pin. It is characterized by

[0008]

In the injection molding die of the present invention, the cavity for molding the boss that is provided so as to project on the molded product is formed by the tubular nest fitted in the movable die, and the tip of this nest is the cavity. On the side that forms the back surface of the molded product, the sleeve core pin that is fitted so as to partially penetrate into the cavity and that forms the boss hole at the center of the boss penetrates almost to the tip position of the nest. Further, a cylindrical sleeve pin for forming the upper end surface of the boss and projecting the boss portion is provided by being inserted between the inner cylinder surface of the insert and the sleeve core pin. The manufacturing cost can be reduced, troubles such as galling of the mold due to the sleeve pin can be eliminated, and correction of the amount of thinned meat at the boss can be easily performed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a main part of an example of an injection molding die of the present invention. In FIG. 1, reference numeral 1 denotes a molded product, which is composed of a molded product main body 11 and a boss 12 provided so as to project from the molded product main body 11. 2 is a fixed type and 3 is a mobile type. The cavity for molding the boss 12 is a cylindrical insert 4 fitted in the movable die 3.
The front end portion 41 of the insert 4 partially penetrates into the molded product body 11 on the rear surface side of the molded product body 11 to form the meat thinning portion 13 on the rising outer peripheral portion of the boss 12. ing.

Reference numeral 5 is a sleeve core pin, and the sleeve core pin 5 is erected from a mounting plate 6 of the movable die 3. The tip end portion 51 of the sleeve core pin 5 is inserted into the center portion of the boss portion 12 to a position almost the same as the tip end portion 41 of the insert 4, and the boss hole 14 is formed.

Reference numeral 7 denotes a sleeve pin, which is erected from a projecting plate 8 and slidably inserted into the inner surface of the insert 4. The depth of insertion of the tip portion 71 of the sleeve pin 7 into the insert 4 at the time of molding by closing the mold is determined by the boss portion 1.
Set by 2 boss heights. Further, the upper end surface of the tip portion 71 of the sleeve pin 7 coincides with the upper end surface 15 of the boss portion 12, the tip portion 71 is a part of the molding die, and when the die is opened after molding, the boss portion 12 is opened. To allow the molded product 1 to be released from the mold.

A sleeve pin 7 is provided on the inner circumference of the insert 4.
The outer periphery of the sleeve pin 7 slides smoothly, and the sleeve core pin 5 slides smoothly on the inner periphery of the sleeve pin 7.
When the mold is opened during molding, the protrusion of the boss portion 12 and the release of the molded product 1 can be made smooth and reliable.

As a material used for the insert 4, it is preferable to use a hardenable steel material, and by hardening the insert 4, it is possible to use a non-hardened steel material for the movable die 3. Also, since the insert 4 is used by being press-fitted into the movable die 3, it can be attached and detached, and the design change and the shape of the boss portion 12
It is possible to easily deal with changes in dimensions.

The shape and dimensions of the insert 4 are not particularly limited to the embodiment, and, for example, in this embodiment,
The outer diameter of the insert 4 is the thinned-out portion 1 of the boss portion 12 of the molded product 1.
The outer diameter of the insert 4 can be larger than the outer diameter of the meat-thinned portion 13, although it does not necessarily need to be the same.

[0015]

In the injection molding die of the present invention, the cavity for molding the boss projectingly provided on the molded product is formed by the cylindrical nest fitted in the movable die, and
A sleeve core pin for forming a boss hole at the center of the boss is fitted into the cavity so that the tip of the nest forms a part of the inside of the cavity on the side forming the back surface of the molded product of the cavity. A cylindrical sleeve pin that is formed so as to penetrate almost to the tip position and that forms the upper end surface of the boss and projects the boss portion is inserted between the inner cylinder surface of the insert and the sleeve core pin. By doing so, it is possible to reduce the manufacturing cost of the die, eliminate the trouble such as the galling of the die by the sleeve pin, and easily perform the correction processing of the amount of the thinned meat at the boss portion. Therefore, it is suitable as an injection molding die for a molded product having a boss portion.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an example of an injection molding die of the present invention.

FIG. 2 is a sectional view showing an example of a conventional mold provided with a boss portion.

[Explanation of symbols]

 1 Molded Product 11 Molded Product Main Body 12 Boss 2 Fixed Mold 3 Moving Mold 4 Nesting 5 Sleeve Core Pin 6 Sleeve Pin

Claims (1)

[Claims] 1. An injection molding die for a molded product comprising a fixed mold and a movable mold, wherein a cavity for molding a boss projecting from the molded product is formed by a cylindrical nest fitted in the movable mold, The sleeve core pin for forming a boss hole at the center of the boss is fitted so that the tip of the nest inserts into the cavity on the side forming the back surface of the molded product of the cavity. A cylindrical sleeve pin that is provided so as to penetrate almost to the tip of the insert and that forms the upper end surface of the boss and projects the boss is inserted between the inner surface of the insert and the sleeve core pin. An injection mold which is characterized by being