JP2002127204A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding capable of molding an article difficult to satisfy a consistency of a mold structure in a prior art due to a shape of the molding by an integral mold and reducing an overall molding cost. SOLUTION: The mold for injection molding molds the molding having first and second undercuts at two positions sandwiching a hook in a mold opening direction. The molds comprises an oblique core 4 movable in a direction perpendicular to the mold opening direction at an outside of the hook A2 as the first undercut, a lifting block 5 disposed at the inside of the part A2 as the second undercut. Thus, when the mold is opened, the first undercut is released from the mold by the core 4, and the inside of the part A2 to become the second undercut from the block 5 is forcibly released from the mold. The block 5 is disposed through a long hole of the oblique core. When the mold is opened, the movement of the oblique core can be lifted while allowing the core to move via the long hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mold for injection molding, and more particularly to a technique for treating an undercut portion when a molded article having two undercut portions is formed.

[0002]

2. Description of the Related Art Conventionally, when molding a molded product having an undercut portion in injection molding, for example, the inclined core is slid in conjunction with a mold opening operation of a movable die, whereby the inclined core causes an undercut. Many techniques for processing a cut portion and releasing a molded product have been provided (for example, see Japanese Patent Application Laid-Open No. 9-109194).

[0003] Therefore, for example, when a molded product A having a main body portion A1 and a hook-shaped portion A2 as shown in Fig. 6A is to be molded by injection molding, if the mold opening direction is the P direction, Since the upper part becomes the first undercut part X and the lower part becomes the second undercut part Y with the hook-shaped part of FIG. 6B interposed therebetween, such a molded product shape does not have a mold structure. There was no.

Therefore, conventionally, the shape of the molded product is changed, or as shown in FIG. 7, the main body portion A1 and the hook-shaped portion A2 are separately formed, and thereafter, the hook-shaped portion A2 is assembled to the main body portion A1. The method of performing the next processing was adopted.

[0005]

However, if the main body portion A1 and the hook-shaped portion A2 are separately formed as in the above-mentioned conventional case, it is necessary to form each member with a mold manufactured respectively. There has been a problem that the mold manufacturing cost increases and the molding cost also increases. In addition, there is a problem that an assembling operation cost for the secondary processing is required.

Further, as shown in FIG. 8, for example, the shape of the tip portion A3 of the hook-shaped portion A2 is changed so as to be straight in the mold opening direction, and the undercut portion is replaced with only the first undercut portion X. By changing to the molded product A to be formed, molding using the inclined core a becomes possible. However, in the mold for molding the molded article A having the above-mentioned shape by the inclined core a, when the inclined core a moves, as shown in FIG. 8, the molded article A is dragged by the inclined core a. That is, there is a problem that the so-called molded product A is likely to be taken up by the inclined core a, which causes a mold release failure of the molded product A. In addition, in FIG. 8, b is a fixed type, c
Is a movable type provided with the inclined core a.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to provide an inclined core and a push-up block even if it is conventionally difficult to establish a mold structure due to the shape of a molded product. Injection molding which can reduce molding costs by using a single mold by utilizing the above and can prevent poor mold release due to the inclined core. To provide a mold.

[0008]

According to a first aspect of the present invention, there is provided an injection molding die having a hook-like portion sandwiched in a mold opening direction.
An injection molding die for molding a molded product having first and second undercut portions at a location, the movable portion being movable in a direction orthogonal to a mold opening direction outside a hook-like portion serving as the first undercut portion. And a push-up block is disposed inside the hook-shaped portion serving as the second undercut portion. When the mold is opened, the first undercut portion is released from the first undercut portion by the inclined core and then pushed up. The inside of the hook-shaped portion serving as the second undercut portion is forcibly released from the block.

The injection molding die according to the second aspect of the present invention
The push-up block is disposed so as to penetrate an elongated hole formed in the inclined shaft portion of the inclined core, and is configured to be able to push up while allowing the inclined core to move by the elongated hole when the mold is opened.

[0010]

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

FIGS. 1 and 2 show the overall construction of an injection mold according to the present invention.

The injection molding die comprises a fixed die 1 and a movable die 2 which is provided so as to be able to clamp and open the die with respect to the fixed die 1.

A cavity 3 corresponding to the shape of a molded product is formed on a mold mating surface (parting line) PL between the fixed mold 1 and the movable mold 2. The cavity 3 is filled with a molten resin injected from an injection nozzle (not shown) through a sprue, a gate, and the like (not shown) formed on the fixed mold 1 side.

Here, the molded product A molded by the cavity 3 has the same shape as the molded product shown in FIG. The shape part A2 is formed integrally. This molded product A
Is for holding and fixing an electric wire harness, for example, and has a shape in which a tip A3 of a hook-like portion A2 is inclined toward the main body A1. That is, as shown in FIG. 6B, in the injection mold, the upper portion is the first undercut portion X and the lower portion is the second undercut portion Y with the hook portion A2 interposed therebetween.

Therefore, in the present invention, the inclined core 4 and the push-up block 5 are provided on the movable mold 2 side in order to process the first and second undercut portions X and Y.

The inclined core 4 is disposed outside the hook-shaped portion A2 of the molded article A, and the push-up block 5 is disposed inside the hook-shaped portion A2, and is fixed to the inclined core 4 and the push-up block 5. Mold A with mold 1 and movable mold 2
Is formed.

As shown in FIG. 1, the inclined core 4 is connected to a projecting plate 21 provided on the movable mold 2 via an inclined shaft portion 41. When the mold is opened, the projecting plate 21 is moved to the cavity 3 side. By moving the first undercut portion X by the action of the inclined shaft portion 41,
Is configured to slide horizontally to the right in FIGS. 1 and 2. The configuration in which the inclined core 4 is slid to the right side of the movable mold 2 in this manner is such that the top surface A4 of the molded product A is curved in the depth direction Q as shown in FIG. Therefore, a mechanism for sliding the inclined core 4 in the depth direction Q cannot be employed.

The push-up block 5 has a base end connected to the protruding plate 21 and a cavity passing through an elongated hole 42 formed in the inclined shaft portion 41 of the inclined core 4 as shown in FIG. 3, and is configured to be pushed up from the cavity 3 toward the fixed mold 1 while allowing the above-described inclined core 4 to slide by the elongated hole 42 with the movement of the protruding plate 21.

Next, the operation of molding the molded article A with the injection mold thus configured will be described.

First, the movable mold 2 is clamped to the fixed mold 1, and a cavity 3 is formed by the fixed mold 1, the movable mold 2, the inclined core 4, and the push-up block 5.
After the molten resin is filled and cooled and solidified, the movable mold 2 is opened and the molded product A is taken out.

In the mold opening operation of the movable mold 2, the projecting plate 21 is moved along with the mold opening operation of the movable mold 2 so that the cavity 3 is opened.
The inclined core 4 moves to the inclined shaft portion 41 by moving to the side.
As a result, the movable die 2 slides to the right in FIGS. 1 and 2 and the push-up block 5 moves so as to project toward the cavity 3. At this time, since the push-up block 5 penetrates the elongated hole 42 of the inclined shaft portion 41 and allows the inclined core 4 to slide, the push-up block 5 moves toward the cavity 3 without disturbing the sliding operation of the inclined core 4. I do.

When the mold opening is completed as shown in FIG. 4, the inclined core 4 is released from the first undercut portion X, and the push-up block 5 is moved to the molded product A.
The whole is in a state of being pushed up from the movable mold 2.

In this state, the release of the molded article A is completed by forcibly pulling the molded article A upward from the block 5 by an appropriate take-out device or operator.

As described above, the molded article A is formed by processing the first undercut portion X and the second undercut portion Y using the inclined core 4 and the push-up block 5 disposed on the movable mold 2. The molded article A having a special shape having the hook-shaped portion A2 can be molded by an integral injection mold.
As a result, it is possible to reduce the mold manufacturing cost and the molding cost, and the secondary processing is not required.

Since the operation of releasing the molded product A from the second undercut portion Y also serves as the operation of finally releasing the molded product A by a take-out device or the like, the two first and second molds are removed. Even when the undercut portions X and Y are processed, the operation at the time of opening the mold is the same as the conventional one, and the molding cycle is also the same as the conventional one.

Further, until the inclined core 4 slides and separates from the first undercut portion X, the push-up block 5 exists in the hook-shaped portion A2 serving as the second undercut portion Y. The push-up block 5 prevents the molded product A from sticking to the inclined core 4 due to the slide. As a result, a phenomenon in which the molded article A is taken off by the inclined core 4 at the time of mold release can be reliably prevented, and an error in taking out the molded article A by the take-out device can be reliably prevented. Can be.

Since the release of the push-up block 5 from the second undercut portion Y is forcibly performed,
At this time, in order to prevent whitening and cracking at the hook-shaped portion A2, the inclination angle θ of the tip A3 of the hook-shaped portion A2 is desirably 45 degrees or less (see FIG. 5).

Further, in order to prevent the mold from galling, it is preferable to use a hardened material for the push-up block 5 and to perform a nitriding treatment on the surface of the inclined core 4.

[0029]

As described above, according to the injection molding die of the present invention, a molded product having the first and second undercut portions at two places with the hook-like portion sandwiched in the mold opening direction. When forming the first undercut portion, an inclined core movable in a direction orthogonal to the mold opening direction is arranged outside the hook portion serving as the first undercut portion, and inside the hook portion serving as the second undercut portion, A push-up block is arranged, and at the time of opening the mold, after the first undercut portion is released by the inclined core, the inside of the hook-shaped portion serving as the second undercut portion is forcibly released from the push-up block. With this configuration, a specially shaped molded product having a hook-shaped portion can be molded by an integral injection mold, thereby reducing mold manufacturing costs and molding costs.
Secondary processing is not required.

Further, the sliding block of the inclined core causes the push-up block to prevent the molded article from sticking to the inclined core, thereby preventing the molded article from being taken up by the inclined core at the time of releasing the mold. As a result, it is possible to reliably prevent a molded product removal error by the removal device, so that stable continuous molding can be performed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall configuration of an injection mold according to the present invention.

FIG. 2 is an enlarged sectional view showing an inclined core and a push-up block provided on a movable die.

FIG. 3 is an enlarged perspective view showing an inclined core and a push-up block.

FIG. 4 is a cross-sectional view showing the overall configuration of an injection molding die in an open state.

FIG. 5 is an enlarged view showing the shape of the tip of a hook-like portion of a molded product.

6A and 6B are diagrams showing the shape of a molded product, wherein FIG. 6A is a perspective view and FIG. 6B is a cross-sectional view.

FIG. 7 is a perspective view showing each member of a molded product.

FIG. 8 is a cross-sectional view showing a conventional injection mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed mold 2 Movable mold 3 Cavity 4 Inclined core 41 Inclined shaft part 42 Long hole 5 Push-up block A Molded product X 1st undercut section Y 2nd undercut section

Claims (2)

[Claims] 1. An injection molding die for molding a molded product having first and second undercut portions at two positions with a hook-like portion sandwiched in a mold opening direction, wherein the first undercut portion is provided. An inclined core movable in a direction perpendicular to the mold opening direction is arranged outside the hook-shaped part serving as a second undercut part, and a push-up block is arranged inside the hook-shaped part serving as the second undercut part. At
After releasing the first undercut part by the inclined core,
A mold for injection molding, characterized in that the inside of a hook-like portion serving as a second undercut portion is forcibly released from the lifting block. 2. The push-up block is disposed so as to penetrate an elongated hole formed in the inclined shaft portion of the inclined core, and is configured to be able to push up while allowing the inclined core to move by the elongated hole when the mold is opened. The injection molding die according to claim 1, wherein: