JP2002113748A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding for a molded article with an undercut part. SOLUTION: A slide core 4 movable provided on a fixed side mold 2 by being interlocked with mold opening and mold closing of a movable side mold 3 is constituted of the first slide core 41 and the second slide core 42 connected with this first slide core 41 through a stopper bolt 5 so as to be relatively movable to the first slide core 41 and an elastic body 6 is provided between the first slide core and the second slide core and a slide core pin 7 which can be inserted into the cavity of the second slide core is provided on the first slide core. Therefore, when the first slide core is moved within a set range by being interlocked with the mold opening of the movable side mold, the movement of the slide core is regulated by means of the elastic body and the apex part of the slide core pin is separated from the undercut part 101 of the molded article. Thereafter, the second slide core moves with the first slide core and is separated from the undercut part of the molded article.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold, and more particularly to an injection mold suitable for molding a molded article having an undercut portion such as a boss.

[0002]

2. Description of the Related Art In general, an injection molding die includes a fixed side die,
The movable mold includes a movable mold that can be clamped and opened with respect to the fixed mold, and a cavity is formed by the clamped fixed mold and the movable mold. Then, a molded product corresponding to the shape of the cavity can be formed by injecting the molten resin into the cavity and solidifying it.

[0003] By the way, as shown in FIG.
Has a relatively long boss 101 protruding laterally, this boss 101 becomes an undercut portion when the mold is opened.

[0004] Such a boss portion (undercut portion)
When molding the molded article 10 having 101, as shown in FIG. 5, a fixed-side mold a is provided with a slide core c which is movable in a direction orthogonal to the mold-opening and mold-clamping directions of the movable-side mold b. The slide core c has a cavity for forming the outer periphery of the boss 101 described above. A driven plate d arranged at a predetermined distance from the slide core c is continuously provided on the slide core c. The driven plate d abuts on the inner side of the driven plate d with the outer peripheral surface of the movable mold b during mold clamping. A contact plate e comprising a first plate e1 and a second plate e2 is provided so as to be detachable via an elastic body f, and comes into contact when the slide core c moves outward by a predetermined amount when the mold is opened. A stopper g for moving the contact plate e outward is provided on the contact plate e. Further, when the mold is opened, a stopper hole for forming a pin hole in the boss portion 101 which is an undercut portion of the molded product 10 is provided. The slide core pin h is connected to the driven plate d through the contact plate e. As a result, when the injection molding die is opened, the slide core pin h is moved by the elasticity of the elastic body f.
The operation of the sleeve pin i that guides the
After retracting the slide core pin h from the undercut portion of the molded product 10, the sleeve pin i is retracted together with the slide core pin h, and the slide core c is detached from the boss portion 101 which is the undercut portion. (See, for example, JP-A-2000-94482).

[0005]

However, in the above-described injection molding die, the driven plate d and the first plate e1 are used as a mechanism for quickly releasing the undercut portion.
And a contact plate e composed of the second plate e2 and a number of other parts are required, so that not only the number of parts is increased, the structure becomes complicated, but also the mold cost is increased.

Also, since various components other than the slide core C are arranged outside the slide core c, an operation stroke of the quick release mechanism is required in addition to the operation stroke of the slide core c. It is necessary to consider a mold size corresponding to this stroke.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an inexpensive injection molding die capable of reliably molding a molded article having an undercut portion with a simple structure. is there.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a cavity corresponding to the shape of a molded article having an undercut portion is formed on a mating surface of a fixed mold and a movable mold, and the movable mold is clamped. In an injection molding die in which a slide core is provided on a fixed mold so as to move in a direction orthogonal to a moving direction of a movable mold in conjunction with opening of the mold, the slide core includes a first slide core and a second slide core. A second slide core connected so as to be able to move relative to only one set of slide cores until it is restricted by the stopper, and between the first slide core and the second slide core. An elastic body that presses in a direction away from each other is provided, and a second slide core is passed through the first slide core and a second slide core corresponding to the undercut portion of the molded product is provided.
A slide core pin that can be inserted into the cavity of the slide core is provided. When the first slide core moves in the set range in conjunction with the opening of the movable mold during injection molding, the second slide pin is provided.
In a state where the movement of the slide core is stopped by being pressed by the elastic body, the tip of the slide core pin is separated from the undercut portion of the molded product, and thereafter, when the first slide core moves together with the second slide core, The two slide cores are detached from the undercut portion of the molded product.

According to the present invention, after the molten resin is injected and filled into the cavity formed by the fixed mold and the movable mold and solidified, and then the movable mold is opened, the movable mold can be moved. The first slide core starts moving in conjunction therewith. in this case,
The second slide core also tries to move,
The movement of the slide core is restricted because the slide core is pressed against the fixed mold by an elastic body disposed between the slide core and the first slide core. Then, when the first slide core moves in the set range, the slide core pin provided on the first slide core moves through the second slide core, and the tip of the slide core pin separates from the undercut portion of the molded product. First
When the slide core moves within the set range, the first slide core comes into contact with the stopper, and the second slide core connected to the first slide core via the stopper moves together with the first slide core. The core comes off from the undercut portion of the molded product.

On the other hand, when the movable mold is closed, the first slide core moves in conjunction with the movement of the movable mold. At this time, the first slide core and the second slide core are pressed by elastic members to a position where they come into contact with the stopper, and the first slide core and the second slide core move together with a set range. If the second slide core is positioned on the fixed mold, further movement of the second slide core is restricted, so that only the first slide core compresses the elastic body between the second slide core and the second slide core. While moving, it comes into contact with the second slide core. At this time, a cavity corresponding to the shape of the molded product is formed, and a slide core pin provided on the first slide core moves through the second slide core, and a tip end thereof corresponds to an undercut portion of the molded product. 2 Inserted into the cavity of the slide core.

As a result, a slide core is constituted by the first slide core and the second slide core which are slidably connected to each other only within a set range, and a stopper is provided between the first slide core and the second slide core. In addition, it is possible to form an injection mold of a molded product having an undercut portion with a simple configuration only by providing an elastic body. Therefore, an inexpensive injection mold having a small number of parts can be obtained, and there is no member for restricting the movement of the slide core outside the slide core. The size of the mold can be determined, and it can be formed compact.

[0012]

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

FIG. 1 shows an injection mold 1 of the present invention.

The injection molding die 1 is used when molding a molded product 10 having a relatively long boss portion (undercut portion) 101. The injection molding die 1 includes a fixed side die 2 and a fixed side die 2. On the other hand, a movable mold 3 that moves up and down to perform mold clamping and mold opening, and a slide core 4 movably provided on the fixed mold 2 in conjunction with mold clamping and mold opening of the movable mold 3. , And a cavity having a shape corresponding to the molded product 10 is formed between the fixed mold 2 and the movable mold 3. The portion corresponding to the boss 101 of the molded product 10 is formed on a second slide core 42 constituting the slide core 4 as described later.

The slide core 4 can be moved in a direction orthogonal to the moving direction of the movable mold 3 by an angular pin or an angular cam (not shown). First slide core 41
And a second slide core 42 connected to the first slide core 41 via the stopper bolt 5 and having a cavity corresponding to the boss 101 of the molded product 10.

The first slide core 41 is provided on the left and right sides of the first slide core 41 with the elastic body 6, specifically, a housing hole 41 a capable of housing a coil spring, and a head of the stopper bolt 5. A sliding hole 41b through which the portion 51 can move is formed, and the accommodation hole 41a and the sliding hole 41b are formed.
Is defined by a seat 411 having a constant thickness. In the seat 411, an insertion hole 41c in which the shaft portion 52 of the stopper bolt 5 is slidable is formed on the same axis as the axis of the accommodation hole 41a and the slide hole 41b. In addition, the second slide core 42 includes the first slide core 41.
A female screw 42a is formed on the shaft center of the insertion hole 41c formed in the seat 411, and can be screwed with a male screw formed in the shaft portion 52 of the stopper bolt 5.

Further, an insertion hole 41d having a diameter corresponding to the boss hole 101a formed in the boss portion 101 of the molded product 10 is formed in the first slide core 41, and the insertion hole 41d has a base end. The slide core pin 7 whose part is fixed to the first slide core 41 is inserted therethrough and protrudes forward by a predetermined length. The second slide core 42 is located on the same axis as the insertion hole 41 d of the first slide core 41, is continuous with the cavity corresponding to the boss 101 of the molded product 10, and has the insertion hole. An insertion hole 42b having a diameter slightly larger than that of the insertion hole 41d is formed.
2b, a sleeve 421 having an inner diameter corresponding to the boss hole 101a described above is provided.

Here, the length of the slide core pin 7 is such that when the first slide core 41 and the second slide core 42 are joined, the tip of the slide core pin 7 Boss part 10 of molded article 10
1 is set so as to be inserted into the cavity formed corresponding to 1.

The elastic member 6 may be a coil spring, a spiral spring, a leaf spring, a leaf spring, or the like.

The insertion hole 42 of the second slide core 42
It is not always necessary to dispose the sleeve 421 in b, and the slide core pin 7 may directly slide in the insertion hole 42b.

In order to assemble the slide core 4 configured as described above, the elastic body 6 is disposed in the accommodation hole 41a of the first slide core 41, and the sleeve 421 is fitted in the insertion hole 42a of the second slide core 42. After the insertion, the first slide core 41 and the second slide core 42 are
The slide core pin 7 provided on the slide core 41 is inserted through the sleeve 421 and the first slide core 41
The shaft portion 52 of the stopper bolt 5 is inserted through the sliding hole 41b of the second member, and the male screw is inserted through the insertion hole 41c of the seat 411 into the second hole.
By screwing into the female screw 42a of the slide core 42, both can be connected integrally.

At this time, the first slide core 41 is attached to the head 51 of the stopper bolt 5 with respect to the second slide core 42.
Can be slid along the shaft portion 52 of the stopper bolt 5 until the abutment with the seat 411. Also, the slide core pin 7 provided on the first slide core 41 is
The slide core 42 can slide along the sleeve 421 provided in the insertion hole 42b.

Since the elastic body 6 is provided between the first slide core 41 and the second slide core 42, the first slide core 41 and the second slide core 42 are provided.
Are pressed away from each other so that the head 51 of the stopper bolt 5 comes into contact with the seat 411.

Next, the operation of the injection mold 1 having the slide core 4 configured as described above will be described.

As shown in FIG. 1, while the movable mold 3 is clamped to the fixed mold 2, a molten resin is injected and filled into the cavity, and the molten resin is solidified.
When the mold is opened, first, the first slide core of the slide core 4 starts moving in conjunction with the mold opening of the movable mold 3.
At this time, the second slide core 42 also attempts to move following the first slide core 4.
1 is pressed by the fixed side mold 2 by the elastic body 6 disposed between them, and the movement thereof is restricted.

Here, when the first slide core 41 moves within the set range, the slide core pin 7 provided on the first slide core 41 also moves along the sleeve 421 provided in the insertion hole 42b of the second slide core 42. It slides, and its tip is separated from the boss 101 of the molded product 10 (see FIG. 2). Therefore, the boss hole 101a can be formed in the boss portion 101.

The first slide core 41 moves the set range,
When the seat 411 abuts against the head 51 of the stopper bolt 5, the second slide core 42 connected to the first slide core 41 via the stopper bolt 5 also moves together with the first slide core 41. Therefore, the second slide core 42 can be detached from the boss 101 serving as an undercut portion of the molded product 10 (see FIG. 3).

On the other hand, when the movable mold 3 is clamped, the first slide core 41 moves in conjunction with the movement of the movable mold 3. At this time, the first slide core 41 and the second slide core 42 are connected to the head 5 of the stopper bolt 5 by the elastic body 6.
1 and the seat 411 are pressed to a position where they come into contact with each other.
The slide core 41 and the second slide core 42 move together with the set range. When the second slide core 42 is positioned on the fixed mold 2, further movement of the second slide core 42 is restricted, so that only the first slide core 42 attaches the elastic body 6 to the second slide core 42. The second slide core 42 moves while compressing between
Abut. Here, a cavity corresponding to the shape of the molded product 10 is formed between the fixed mold 2 and the movable mold 3, and the slide core pins 7 provided on the first slide core 42 are attached to the second slide core 42. It slides along the provided sleeve 421, and its tip is inserted into the cavity of the second slide core 42 corresponding to the undercut portion of the molded product 10.

In the above-described embodiment, the first
Although the case where the elastic body 6 is accommodated in the slide core 41 and the seat 411 that contacts the stopper bolt 5 is formed has been illustrated, the sliding of the first slide core 41 and the second slide core 42 is relative. Alternatively, the elastic body 6 may be housed in the second slide core 42, and a seat that can abut against the stopper bolt may be formed.

The use of the stopper bolt 5 allows the head 51 to be used as a stopper that can abut on the seat 411, and the shaft 52 to serve as a guide member for the first slide core 41 with respect to the second slide core 42. Although the case where it is used has been described, the guide member and the stopper may be separately provided.

[0031]

As described above, according to the present invention, a slide core is constituted by a first slide core and a second slide core which are slidably connected to each other only within a set range. With a simple configuration in which only a stopper and an elastic body are provided between the second slide core and the second slide core, it is possible to form an injection mold of a molded product having an undercut portion. Therefore, an inexpensive injection mold having a small number of parts can be obtained, and there is no member for restricting the movement of the slide core outside the slide core. The size of the mold can be determined, and it can be formed compact.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view illustrating a state in which the injection mold of FIG. 1 is opened.

FIG. 3 is a cross-sectional view illustrating a state in which the injection mold of FIG. 1 is opened.

FIG. 4 is a perspective view showing a partly omitted molded product having a boss portion serving as an undercut portion.

FIG. 5 is a partial cross-sectional view showing a part of a conventional injection mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection mold 2 Fixed side mold 3 Movable mold 4 Slide core 41 First slide core 42 Second slide core 5 Stopper bolt 51 Head 52 Shaft 6 Elastic body 7 Slide core pin 10 Molded product 101 Boss (undercut) Part) 101a boss hole

Claims (1)

[Claims] 1. A cavity corresponding to the shape of a molded product having an undercut portion on a mating surface of a fixed mold and a movable mold is formed, and a movable side is interlocked with mold clamping and mold opening of the movable mold. In an injection molding die in which a slide core is provided on a stationary mold so as to move in a direction orthogonal to the direction of movement of the mold, the slide core is a first slide core and a stopper is provided with respect to the first slide core. And a second slide core connected so as to be relatively movable only in a set range up to the restriction. The first slide core and the second slide core are pressed in a direction away from each other. An elastic body is provided, and a slide which can be inserted into the first slide core through the second slide core and inserted into a cavity of the second slide core corresponding to the undercut portion of the molded product. A core pin is provided, and during injection molding, when the first slide core moves in the set range in conjunction with the opening of the movable mold, the movement of the second slide core is pressed by the elastic body and is prevented. , The tip of the slide core pin is separated from the undercut of the molded product,
Thereafter, when the first slide core moves together with the second slide core, the second slide core is separated from the undercut portion of the molded product.