JP2000102953A - Die for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die for injection molding which has a simple construction and does not require the use of a hydraulic pump or the like. SOLUTION: The die for injection molding comprises a fixed side die 1 and a moving side die 2, and when both the dies are combined with each other, a cavity 3 is formed between both the dies 1, 2. An insert 53 for forming an undercut part is provided in the die 1 so as to be moved back and forth in the cavity 3 by a fluid pressure cylinder 5. A fluid cylinder 4 is provided in the die 1 so as to act in association with the cylinder 5, and an operation rod 42 extends from a piston 41 in the cylinder 4 so that when the dies 1, 2 are combined, the insert 53 is put into the cavity 3 by the action of the rod 42.

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 metal mold suitable for use in molding a molded article having an undercut portion.

[0002]

2. Description of the Related Art Conventionally, as an injection molding die used for molding a molded article having an undercut portion, for example, a slide core as described in JP-A-2-107419 or the like is used. There is known a slide core in which a core pin for forming an undercut portion of a molded product is protruded from a slide core.

[0003] As such an injection molding die, for example, an inclined pin is inserted into an inclined hole provided in a slide core to move the slide core when the die is opened. The slide core is moved by sliding the inclined pin in the inclined hole, and the core pin of the slide core is detached from the undercut portion of the molded product.

[0004] Other injection molding dies used for molding other molded products having an undercut portion include:
2. Description of the Related Art There is known a structure in which a core pin for forming an undercut portion is connected to a piston of a hydraulic cylinder, and the core pin is moved into and out of a cavity by operation of the hydraulic cylinder.

[0005]

However, the conventional mold for injection molding using a slide core has many drawbacks such as a large number of parts, a complicated structure, and many failures.

An injection molding die in which a core pin for molding the above described undercut portion is connected to a piston of a fluid pressure cylinder has a simple structure and has few advantages in terms of fluid pressure. A hydraulic pump or the like is indispensable as a power source of the cylinder, and there is a problem that much work time is required for connection and mounting between the hydraulic cylinder and the hydraulic pump and the like, and a reduction in productivity is unavoidable.

[0007] The present invention has been made in view of the above-mentioned problems in the conventional injection mold, and an object thereof is to solve the problems in the conventional injection mold. An object of the present invention is to provide an injection molding die which has a simple structure and does not require the use of a hydraulic pump or the like.

[0008]

Means for Solving the Problems In order to achieve the above-mentioned object, in the injection mold of the present invention, a fixed mold and a movable mold are provided, and the fixed mold and the movable mold are provided. A mold for injection molding in which a cavity is formed between both dies when the dies and the mold are closed at the dividing surface, and at least one of the two dies is provided in the cavity with a fluid pressure cylinder. A nest for forming an undercut portion that moves forward and backward is provided, a fluid cylinder that is interlocked with a fluid pressure cylinder is provided in a mold provided with the nest for forming an undercut portion, and an operating rod extends from a piston in the fluid cylinder. When the mold is closed, the nest for forming the undercut portion enters into the cavity by the operation of the operating rod.

In the injection molding die of the present invention, the fluid pressure cylinder may be an air cylinder operated by compressed air or a hydraulic cylinder operated by hydraulic pressure.

In the injection mold of the present invention, the nest for forming the undercut portion may be provided in one of the fixed mold and the movable mold. It may be provided.

In the present invention, at least one of the two dies is provided with a nest for forming an undercut portion which moves into and out of the cavity by a fluid pressure cylinder. A fluid cylinder interlocking with the fluid pressure cylinder is provided in the provided mold, and an operating rod is extended from a piston in the fluid cylinder. When the mold is closed, the nest for forming the undercut portion is inserted into the cavity by the operation of the operating rod. Since it is designed to enter, the structure is simple, there are few failures, and the hydraulic cylinder does not require a special power source such as a hydraulic pump.

[0012]

FIG. 1 is a cross-sectional view showing an example of an injection mold according to the present invention when the mold is closed, and FIG. 2 is a cross-sectional view at the start of mold opening. In these figures, 1 is a fixed mold, 11 is a locate ring of the fixed mold 1, 12 is a mold mounting plate of the fixed mold 1, 13 is a mold plate of the fixed mold 1,
Reference numeral 14 denotes a guide pin mounted on the mold mounting plate 12.

Reference numeral 2 denotes a movable side mold, 21 denotes a mold mounting plate of the movable side mold 2, 22 denotes a mold plate of the movable side mold 2, 23 denotes a spacer block, and 24 denotes a guide pin attached to the mold plate 22. , 25 are ejector pin mounting plates, and 26 is an ejector pin mounted on the ejector pin mounting plate.

When the fixed mold 1 and the movable mold 2 are closed, the mold plate 13 of the fixed mold 1 and the mold plate 22 of the movable mold 2 are closed.
Between them, a cavity 3 having a shape corresponding to the shape of the container-like molded product 6 to be molded as shown in FIG. 4 is formed.

A recess 131 is formed in the mold plate 13 of the fixed mold 1, and a compression coil spring 132 is inserted between the bottom of the recess 131 and the mold mounting plate 12 of the fixed mold 1. As shown in FIG. 2, when the mold opening between the fixed mold 1 and the movable mold 2 starts, the restoring force of the compression coil spring 132 causes the mold plate 13 and the mold mounting plate 12 of the fixed mold 1 to move. Is formed between them.

A fluid cylinder 4 and a hydraulic cylinder 5 are mounted on a mold plate 13 of the fixed mold 1. As shown in FIG. 3 in an enlarged manner, a piston 41 is inserted into the fluid cylinder 4 so as to be able to reciprocate as shown by arrows a and b, and an operating rod 42 is attached to the piston 41.
A lid 43 is attached to one end of the fluid cylinder 4, and a compression coil spring 4 is provided between the lid 43 and the piston 41.
The piston 41 is moved to the other end of the fluid cylinder 4 as shown by an arrow a by the restoring force of the compression coil spring 44, and the operating rod 4 is moved by the movement of the piston 41.
2 protrudes as shown by arrow a. Fluid flow holes 45 and 46 are formed near both ends of the fluid cylinder 4.

At the tip of the operating rod 51 of the hydraulic cylinder 5, there is provided a guide plate 52 which can move within a recess 133 provided in the template 13. A nest 53 for forming an undercut portion projects from the guide plate 52. Have been.

The hydraulic cylinder 5 and the fluid cylinder 4 are connected by hydraulic hoses 54, 55. As shown in FIG. 1, when the fixed mold 1 and the movable mold 2 are closed, the tip of the operating rod 42 abuts against the mold mounting plate 12, so that the operating rod 42 and the piston 41 are retracted in the direction of arrow b. When the piston 41 is retracted, oil (not shown) in the fluid cylinder 4 is discharged from the fluid communication hole 46, and the pressure of the discharged oil is transmitted to the hydraulic cylinder 5 by the hydraulic hose 55, so that the nest for forming the undercut portion is formed. 53 is made to enter the cavity 3.

As shown in FIG. 2, a gap S is formed between the mold plate 13 of the fixed mold 1 and the mold mounting plate 12 when the fixed mold 1 and the movable mold 2 start opening. Operating rod 42
Is separated from the mold mounting plate 12, the piston 41 in the fluid cylinder 4 advances in the direction of arrow a by the restoring force of the compression coil spring 44, and the oil (not shown) in the fluid cylinder 4 The pressure of the discharged oil is discharged from the hole 45 and transmitted to the hydraulic cylinder 5 by the hydraulic hose 54, whereby the nest 53 for forming the undercut portion is retracted from the inside of the cavity 3.

Since the injection mold of the present invention shown in FIGS. 1 and 2 has the above-described structure, the fixed mold 1 and the movable mold 2 are connected to each other as shown in FIG. When the mold is closed, the tip of the operating rod 42 provided in the fluid cylinder 4 abuts on the mold mounting plate 12, and the nest 53 for forming the undercut portion enters the cavity 3 by the action of the hydraulic cylinder 5.

As a result of the injection of the molten resin into the cavity 3 in such a state, the container-like molded product 6 shown in FIG. 4 is formed in the cavity 3 and becomes an undercut portion by the nest 53 for forming the undercut portion. The through hole 61 is formed.

Next, as shown in FIG.
When the mold opening between the movable mold 2 and the movable mold 2 starts, a gap S is formed between the mold plate 13 of the fixed mold 1 and the mold mounting plate 12,
When the mold mounting plate 12 is separated from the tip of the operating rod 42, the nest 53 for forming the undercut portion retreats from the inside of the cavity 3 by the action of the hydraulic cylinder 5, and the mold of the fixed mold 1 and the movable mold 2 is formed. After opening, the container-shaped molded article 6 shown in FIG.

In the injection mold of the present invention shown in FIGS. 1 and 2, a fixed mold 1 is provided with a nest 53 for forming an undercut portion which advances and retreats into the cavity 3 by the operation of the hydraulic cylinder 5. Fluid pressure cylinder 5 in side mold 1
And a fluid cylinder 4 interlocked with the fluid cylinder 4 is provided.
An operating rod 42 is extended from a piston 41 in the inside, and when the mold is closed, the nest 42 for forming the undercut portion enters the cavity 3 by the operation of the operating rod 42, so that the structure is simple. There are few failures, and the hydraulic cylinder does not require a special power source such as a hydraulic pump.

Although the embodiment of the present invention has been described with reference to the drawings, the specific configuration of the present invention is not limited to the illustrated embodiment, and the design change within a range not departing from the gist of the present invention. Are included in the present invention.

For example, instead of being applied to a so-called vertical injection molding die in which the movable die is moved vertically from the fixed die as in the illustrated embodiment, the movable die is fixed. The present invention may be applied to a so-called horizontal injection mold which is moved in a lateral direction from a side mold.

Also, instead of making the tip of the operating rod of the fluid cylinder abut the mounting plate of the fixed mold as in the illustrated embodiment, the tip of the operating rod of the fluid cylinder is attached to the moving mold. You may make it contact | abut on a parting surface.

[0027]

According to the injection molding die of the present invention, the structure is simple, there are few failures, and the fluid pressure cylinder does not require a special power source such as a hydraulic pump. Improvement and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a state of an example of an injection mold according to the present invention when the mold is closed.

FIG. 2 is a cross-sectional view showing a state of the injection mold of the present invention shown in FIG. 1 at the start of mold opening.

FIG. 3 is an enlarged sectional view showing a fluid cylinder of the injection mold of the present invention shown in FIGS. 1 and 2;

FIG. 4 is a perspective view of a molded product formed by the injection molding die of the present invention shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed side mold 11 Locating ring 12 Mold mounting plate 13 Mold plate 14 Guide pin 2 Moving mold 21 Mold mounting plate 22 Mold plate 23 Spacer block 24 Guide pin 25 Ejector pin mounting plate 26 Ejector pin 3 Cavity 4 Fluid Cylinder 41 Piston 42 Operating rod 5 Fluid pressure cylinder 51 Operating rod 52 Guide plate 53 Nest for forming undercut portion 6 Molded product 61 Through hole serving as undercut portion

Claims (1)

[Claims] 1. A fixed mold and a movable mold are provided,
An injection molding mold in which a cavity is formed between the fixed mold and the movable mold when the mold is closed.
At least one of the two dies is provided with a nest for forming an undercut portion which moves into and out of the cavity by a fluid pressure cylinder, and the mold provided with the nest for forming the undercut portion is interlocked with the fluid pressure cylinder. A fluid cylinder is provided, an operating rod is extended from a piston in the fluid cylinder, and when the mold is closed, the nest for forming the undercut portion enters the cavity by the operation of the operating rod. Mold for injection molding.