JP2003080570A - Mold for injection molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold for injection molding having a movable core including high durability with a simple constitution. SOLUTION: The mold for injection molding injection molds a molding having an undercut in a cavity formed by a plurality of mold sections 12 which can relatively move. The mold comprises a section 16 for forming the undercut, the movable core 14 having a pair of outer surfaces 20 and 22 parallel to each other and provided on the same side face as the side face provided with the section having the undercut and an opposite side face of the side face and movable to the mold section, and a pair of guide faces 24, 26 disposed in parallel oppositely to each other to guide the movable core between a molding position assembled in the mold section and a removing position projected from the mold section and deviated in an opposite direction to the section formed with the undercut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die, and more particularly to an injection molding die having a movable core.

[0002]

2. Description of the Related Art Generally, in injection molding, a mold having a fixed mold and a movable mold that is movable with respect to the fixed mold is used. A molten material is injected and cured in a cavity, which is a space formed between the molds, and the two molds are separated (mold open) to take out the product molded in the cavity.

When a molded product having a boss hole, an undercut portion, etc. is manufactured by injection molding, a boss hole portion, an undercut portion, etc. of the molded product (hereinafter collectively referred to simply as "undercut"). , It interferes with the separation of the movable mold and the fixed mold after the injection molding, or the removal of the product from the mold. Therefore, at the time of injection of the molten material, the tip portion is arranged at a predetermined position in the cavity to form an undercut, and at the time of opening the mold after curing the molten material, it is moved from the predetermined position in the cavity to the outside of the cavity. Thus, a movable core (movable core) is used that enables mold separation and product removal.

As such a movable core, a slide core is generally used in which a side core is separated from and close to a cavity by utilizing opening / closing movement of a mold. However, the slide core has a complicated mechanism and is not suitable for forming an undercut having a small size or an undercut located inside a product.

Therefore, when forming an undercut having a small size or an undercut located inside the product, a movable core is attached to the tip of a shank 101 made of a leaf spring as shown in FIGS. 1 and 2. A spring core 100 to which 102 is attached is used.

[0006]

[Problems to be Solved by the Invention] This spring core 1
As shown in FIG. 1, when the mold is closed, the movable core 102 is arranged in the concave portion 106 of one mold portion (core block) 104 so that the movable core 102 forms a cavity wall for molding the undercut portion 108. Is placed in the
Along with the ejector pin 110, it projects from the mold part 104, and at this time, the molded product 11 is automatically produced by the elasticity of the shank.
The second undercut portion 108 is attached to the mold portion 104.

For this reason, in the spring core 100, the movable core 102 is pressed against the wall surface of the recess 106 of the mold portion 104 by the shank 101 every time the mold portion 104 is opened and closed, and the recess 106 of the mold portion 104 is pressed.
Will come and go. Therefore, when the injection molding is repeated, the movable core 102 and the mold part 104 (that is, the mold) are worn out, and there is a problem that durability is deteriorated.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an injection molding die having a movable core having a simple structure and high durability.

[0009]

According to the present invention, there is provided an injection-molding die for injection-molding a molded article having an undercut in a cavity formed by a plurality of relatively movable die parts. A portion having the undercut and a side surface that is the same as the side surface on which the portion that forms the undercut is provided, and a pair of outer surfaces that are parallel to each other and that are provided on opposite side surfaces of the side surface, A movable core movable with respect to the mold part, and abutting on each of the pair of outer surfaces, the movable core being incorporated in the mold part, a molding position, and a protrusion from the mold part and the undercut. And a pair of guide surfaces arranged in parallel and facing each other for guiding between a portion forming the groove and a removal position displaced in the opposite direction. It is provided.

According to this structure, the outer surfaces of the movable core, which face in opposite directions, are sandwiched by the pair of guide surfaces and slide along the guide surfaces so that the outer surfaces of the movable core slide. Moves between the molding and unloading positions. Therefore, a large force does not act between the outer surface and the guide surface, and the wear between them is reduced.

According to a preferred aspect of the present invention, the movable core is connected to the tip of the flexible shank.
The flexibility of the shank is preferably such that it allows lateral displacement of the movable core to the removal position. With such flexibility, a large force does not act between the outer surface and the guide surface.

According to another preferred aspect of the present invention, the shank is arranged so as to extend in a direction orthogonal to a dividing surface of the mold.

According to another preferred aspect of the present invention, an ejector pin having a tip portion protruding from the mold portion to remove the molded article from the mold portion, and a proximal end portion of the ejector pin are attached to the mold. And an ejector plate that is movable with respect to the proximal end of the shank,
The movable core, which is attached to the ejector plate and is connected to the tip of the shank, is moved to the removal position in synchronization with the protrusion of the ejector pin.

With this structure, the molded product can be efficiently removed from the mold.

According to another aspect of the present invention, the metal mold used for an injection molding mold for injection molding a molded product having an undercut in a cavity formed by a plurality of mold parts capable of relative movement. A movable core that is movable with respect to the mold part, and is provided on the same side surface as the portion forming the undercut, the side surface on which the portion forming the undercut is provided, and the side surface opposite to this side surface. And a pair of outer surfaces that are parallel to each other. The movable core is preferably connected to the tip of the flexible shank.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An injection molding die according to a preferred embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 3 shows the movable mold 1 of the injection molding mold in the mold closed state.
4 is a schematic cross-sectional view showing 0, and FIG. 4 is a schematic cross-sectional view showing the movable mold 10 of the injection molding mold in the mold open state.

The injection molding die of this embodiment includes a fixed die (not shown) which is a fixed die and a movable die 10 which is a movable die movable with respect to the fixed die. Is equipped with. These fixed mold and movable mold 10 are injection molded so that they can be moved between a mold open position where they are separated from each other and a mold closing position where they are joined to form a cavity corresponding to the product shape. Mounted on a machine (not shown). This injection molding die, like a known injection molding die, injects a molten resin material into a cavity formed between the fixed die and the movable die 10 at the die closing position to perform injection molding. After that, the movable mold 10 is moved to the mold opening position (the mold is opened), and the cured product is removed from the mold.

As shown in FIGS. 3 and 4, the molded product (product) P molded by this injection molding die has a projection p1 extending inwardly on the inner side at one end side. However, this part is the undercut part.

The movable die 10 is movable with respect to the core block 12 and a core block (die portion) 12 that forms a part of a cavity for injection molding.
And a loose core (movable core) 14 forming a part of the.

The loose core 14 is a protrusion p1 of the molded product P.
Which is a component for molding, is provided with a recess 16 having a shape complementary to the protrusion p1, and is housed in a housing 18 formed in the core block 12. The lower end portion (cabinet block side) of the loose core 14 is the protrusion 1 of the molded product P.
A pair of outer surfaces 20 and 22 that extend parallel to each other and that are inclined in a direction away from the recess 16 are provided on the side of the recess 16 that forms 6 and the opposite side thereof. Further, the accommodating portion 18 of the core block 12 has a shape complementary to the lower end portion of the loose core 14 on which the outer surfaces 20 and 22 are formed, and a pair of parallel guide surfaces that come into contact with the outer surfaces 20 and 22. Two
4 and 26 are provided.

The loose core 14 has outer surfaces 20, 22
By sliding along the guide surfaces 24, 26 of the accommodating portion 18, the molding position (FIG. 3) where injection molding is performed by being incorporated in the core block 12 and a direction opposite to the concave portion 16 protruding from the core block 12 are performed. It is configured so that it can be moved to and from the removal position (FIG. 4) which is displaced to the right.
“Displaced in the direction opposite to the recess 16” means that the lateral position in FIGS. 3 and 4 is displaced from the molding position in the direction opposite to the recess 16 (arrow A direction, that is, leftward direction). Point to.

A flexible shank 28 is connected to the lower end of the loose core 14. The shank 28 has its tip portion inserted into a notch portion formed in the lower end portion of the loose core 14 and welded therein,
It is connected to the loose core 14. In addition, loose core 1
The connection method between the 4 and the shank 28 may be another method such as screwing. The base end 30 of the shank 28 is fixed between the upper ejector plate 32 and the lower ejector plate 34. These upper ejector plates 3
2 and the lower ejector plate 34, a molded product P
The base end 38 of the ejector pin 36 protruding from the core block 12 is also fixed. The shank 28 and the ejector pin 36 extend toward the upper ejector plate 32 and the lower ejector plate 34 through through holes 42 and 44 formed in the receiving plate 40 to which the core block 12 is attached. That is, the shank 28
The movable mold 10 of the injection molding die and the movable mold extend in a direction orthogonal to the dividing surface.

In this embodiment, the upper ejector plate 32 and the lower ejector plate 34 are the core block 1
2 is movable with respect to the upper ejector plate 3
2 and the lower ejector plate 34 approaching the core block 12, from the state shown in FIG.
The loose core 14 attached to the tip of the ejector pin 8 and the tip of the ejector pin 36 are configured to move to the state of FIG. And
In this embodiment, the outer surfaces 20, 22 of the loose core 14 are
When the loose core 14 is projected from the core block 12 by the shank 28, the loose core 14 laterally moves in the direction opposite to the concave portion 16 and the concave portions of the loose core 14 contact each other. The angle 16 is set so as to come off the projection p1 of the molded product P.

As described above, in the movable mold 10 of the injection molding die of this embodiment, the outer surface 20 of the loose core 14,
22 and the guide surfaces 24, 26 that come into contact with the concave surface 22
6 (that is, extending obliquely in a direction away from the projection p1 of the molded product P. Therefore, the injection molding is completed, the mold is opened, and the molded product P is removed from the core block 12 by the ejector pin 36. At this time, in synchronization with the movement of the ejector pin 36, the loose core 14 projects laterally in the direction opposite to the recess 16 shown by the arrow A in FIG. As a result, the concave portion 16 of the loose core 14 is formed in the molded product P.
Will be disengaged from the protrusion p1.

Since the displacement due to the lateral movement of the loose core 14 in the direction of the arrow A is absorbed by the bending of the shank 28, the shank 28 has the flexibility to allow the displacement of the loose core 14, The through hole 42 through which the shank 28 is inserted has an inner diameter that allows the shank 28 to flex.

The present invention is not limited to the above embodiment, and various changes and modifications can be made within the scope of the matters described in the claims.

In the above embodiment, the loose core is for forming the projection p1 of the molded product P, but the present invention is for injection molding provided with a loose core for forming another undercut portion. It can also be applied to molds.

In the above embodiment, the protrusion which is the undercut portion is formed inside the molded product. However, the present invention is a loose core for forming the undercut portion outside the molded product. It can also be used for an injection molding die having a (movable core).

[0029]

According to the present invention, there is provided a mold for injection molding having a movable core, which has a simple structure and high durability.

[Brief description of drawings]

1 is a schematic cross-sectional view showing a movable mold with a prior art spring core in a mold closed position.

FIG. 2 is a schematic cross-sectional view showing a movable mold with a prior art spring core in a mold open position.

FIG. 3 is a schematic cross-sectional view of a movable mold of the injection molding mold according to the embodiment of the present invention in a mold closed position.

FIG. 4 is a schematic cross-sectional view of a movable die of the injection molding die according to the exemplary embodiment of the present invention in a die open position.

[Explanation of symbols]

P: Molded product p1: protrusion 10: movable 12: Cabrock 14: Loose Core 16: Recess 18: Housing section 20, 22: outer surface 24, 26: guide surface 28: Shank

Claims (6)

[Claims] 1. An injection molding die for injection-molding a molded article having an undercut in a cavity formed by a plurality of relatively movable die parts, the portion forming the undercut, Movable movably with respect to the mold part, having a side surface provided with a portion forming the undercut and a pair of outer surfaces provided on opposite side surfaces of the side surface and being parallel to each other. A core and each of the pair of outer surfaces, abutting the movable core,
Guided between a molding position incorporated in the mold part and a removal position projecting from the mold part and offset in a direction opposite to the part forming the undercut, arranged parallel to each other. And a pair of guide surfaces, and an injection molding die. 2. The mold for injection molding according to claim 1, wherein the movable core is connected to a tip portion of a flexible shank. 3. The mold for injection molding according to claim 2, wherein the shank is arranged so as to extend in a direction orthogonal to a dividing surface of the mold. 4. An ejector pin having a tip portion protruding from the mold portion to remove the molded product from the mold portion, and an ejector pin to which a base end portion of the ejector pin is attached and is movable with respect to the mold portion. A plate, a base end portion of the shank is attached to the ejector plate, and the movable core connected to the tip end portion of the shank is moved to the removal position in synchronization with the protrusion of the ejector pin. The mold for injection molding according to claim 2 or 3. 5. A mold part used in an injection molding mold for injection molding a molded article having an undercut in a cavity formed by a plurality of mold parts that are relatively movable. A movable core, a portion forming the undercut, and a pair of outer surfaces provided on the same side surface on which the portion forming the undercut is provided and on opposite side surfaces of the side surface and being parallel to each other. A movable core having: 6. The movable core according to claim 5, wherein the movable core is connected to the distal end portion of the flexible shank.