JPH0788903A - Injection mold - Google Patents

Abstract

PURPOSE:To provide an injection mold capable of accurately and simply molding a molded product having an undercut. CONSTITUTION:At least one of the front male mold A1 and rear male mold constituting a male mold is constituted of a piramidal core 1, the wedge-shaped cores 2, 2' arranged to the inclined surfaces 1a, 1b of the core 1 and the side cores 3, 3' coming into contact with the front inclined surfaces 1c, 2c and rear inclined surfaces of both cores and ridges 4 are provided to the inclined surfaces of the core 1 and one of the inclined inner surfaces of the wedge-shaped cores in parallel to the inclined surfaces while the guide grooves 14 receiving the ridges 4 are provided to the other one of the inclined inner surfaces 2a of the wedge-shaped cores and undercuts 12, 13 are continuously provided to the outer peripheral surfaces 2b of the wedge-shaped cores and the outer peripheral surfaces 3b of the side cores. Further, the wedge-shaped cores are slid toward the head part accompanied by the separation of the core by a control device inserting the male mold movable plate in the through-holes provided to the wedge-shaped cores to engage the same with the through-holes to be separated along with the core and, after the core and the wedge-shaped cores are separated, the side cores can be allowed to approach each other toward the center.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for injection molding of synthetic resin products having an undercut on the outer circumference.

[0002]

2. Description of the Related Art In a synthetic resin product having an undercut on its outer circumference, the undercut portion is engaged with a male die and a female die, so that the male and female dies are divided. Among them, the female mold can be easily divided because it fits on the outside of the molded product, but the male mold must be made smaller than the inside of the molded product, so various ideas have been elaborated. . For example, a male mold is composed of a tapered core and a split mold arranged on the outer periphery thereof, and the split mold is divided into a mold that recedes first and a mold that recedes later. (For example, Japanese Utility Model Publication No. 53-42618, Japanese Patent Publication No. 59-1.
4333, JP 59-150715, JP 59-38032
Issue)

A male die is formed of a pyramidal core, first split cores and second split cores arranged alternately on the outer peripheral surface of the core, and in the mold clamping direction interposed between the outer peripheral surface of the core core and the first split core. A tapered core, a split core that approaches the inner circumference when the wedge is removed, a rectangular pyramid core, first split cores arranged on the left and right side surfaces thereof, and a core and a first split It is known that the core is composed of a second split core arranged on both sides of the core. (For example, Japanese Patent Publication No. 1-34622, Japanese Patent Publication No. 3-69
(697 publication)

[0004]

A male die in which a core core is formed in a pyramid shape or a rectangular pyramid shape, a split core is arranged on the outer peripheral surface of the core core, and the split core is controlled at one time by following the reciprocation of the core core. In that case, there are problems that the shape of the molded product and the size of the undercut are limited, and that the mold structure becomes complicated and the cost becomes high. Even in the male mold that divides the split core into two parts, that is, the first operation group and the second operation group, there are substantially the same problems.

In any of the male molds, since all of the split cores are controlled by the core core, when the molten resin infiltrates between the core core and the split cores or between the split cores and the resin is solidified. There was a problem that caused a failure. Therefore, the present invention has been made in view of the above problems of the prior art, and an object of the present invention is to accurately and easily mold an injection-molded article having an undercut. To provide the mold.

[0006]

In order to achieve the above object, in the injection molding die of the present invention, at least one of the front male die and the rear male die forming the male die is a pyramidal core. A core, a wedge-shaped core arranged on the left and right inclined surfaces of the core core, and a side core that is in contact with the front slope and the rear slope of both cores. The wedge-shaped core outer peripheral surface and the core core outer peripheral surface are continuously undercut. On the other hand, a core control device that slides the wedge-shaped core to the front side with the detachment of the core core and separates together with the core core is provided on the male mold movable plate, and the side cores are mutually connected after the core core and the wedge-shaped core are detached. It is designed to be accessible.

A wedge-shaped core is provided by providing a ridge parallel to the inclined surface on one of the left and right inclined surfaces of the core core and an inclined inner surface of the wedge-shaped core facing the inclined surface, and a guide groove for inserting the protrusion on the other. It is designed to be slidable along the inclined surface of the core core, and a through hole parallel to the inclined surface of the core core is formed in the wedge-shaped core, and the male die movable plate is inserted and locked in the through hole of the wedge-shaped core. With a rod
A core control device including a spring for pressing the wedge-shaped core to the tapered side of the core is attached.

[0008]

At least one of the front male mold and the rear male mold forming the male mold has a pyramidal core core, a wedge-shaped core arranged on the left and right inclined surfaces of the core core, and a front slope of the core core and the wedge-shaped core. ,
In addition, the wedge-shaped core is configured to be slidable along the left and right inclined surfaces of the core core, the side core being in contact with the rear slope, and the wedge-shaped core is slid to the front side by the core control device when the core core is separated. They approach each other toward the center of the male mold, are locked to the core core, and are separated from each other. The side cores are brought close to each other after the core core and the wedge core have been separated to enable injection of the undercut molded product.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the structure of an injection molding die according to the present invention will be described with reference to FIGS.
A2 and female dies B1 and B2 that are divided into left and right or up and down, and at least one of the front male die A1 and the rear male die A2 and the pyramidal core core 1 as shown in FIGS. Wedge-shaped cores 2, 2'arranged on the left and right inclined surfaces 1a, 1b of the core core 1, and the front slopes 1c, 2c and the rear slopes 1d, 2d of the core core 1 and the wedge-shaped cores 2, 2 '. The side cores 3 and 3'are divided and the undercuts 12 and 13 are continuously formed on the wedge-shaped core outer peripheral surface 2b and the side core outer peripheral surface 3b.

Since the structures of the female dies B1 and B2 which are divided into left and right or up and down are the same as the conventional ones, the description thereof will be omitted. The present invention is characterized in that at least one of the front male mold A1 and the rear male mold A2 is further divided and configured, and the drawings show the case where the front male mold A1 is dividedly configured. Based on the description, the core core 1 that constitutes the front male mold A1 has the left and right inclined surfaces 1a and 1b with an inclination angle θ that spreads toward the rear end from the front end.
And the front and rear slopes that also slightly expand toward the rear end
Formed from 1c and 1d, it has a pyramidal shape and the left and right inclined surfaces 1
Protrusions 4 are provided on a and 1b, respectively, and the main cylinder P1 is provided at the rear.
Attach and reciprocate.

The wedge-shaped core 2 is thinned from the front end toward the rear end by an inclined inner surface 2a having an inclination angle θ opposed to the left inclined surface 1a of the core core 1 and an outer peripheral surface 2b having the center of the front male mold A1 as a fulcrum. The front slope 2c and the rear slope 2d are widened toward the rear end from the front end similarly to the front and rear slopes 1c and 1d of the core 1 and are flush with the front and rear slopes 1c and 1d of the core 1. The slanting inner surface 2a is provided with a guide groove 14 to be inserted into the protrusion 4 of the core core slanting surface 1a, the outer peripheral surface 2b is formed with an undercut 12, and the wedge-shaped core 2 is parallel to the slanting inner surface 2a. The through holes 5 are formed respectively. The wedge-shaped core 2 ′ has a symmetrical shape with the wedge-shaped core 2, and thus the description thereof will be omitted.

The through hole 5 formed in the wedge-shaped cores 2, 2'is
As shown in FIG. 4, a small diameter portion 5a is formed in the middle portion of the wedge-shaped cores 2, 2 ', and large diameter portions 5b, 5c are formed on the front and rear sides to form a step. Male die movable plate integrally formed with the core 1 in the through hole 5.
The core control device 20 is inserted and locked by means of the core control device 20. The core control device 20 inserts the rod 8 into the through hole 5 of the wedge-shaped cores 2 and 2'and the wedge-shaped cores 2 and 2'which are fitted and inserted into the rods 8. Core 1
The rod 8 is provided with a head 9a which is inserted into the front side large diameter portion 5b of the through hole 5 and the rear side large diameter portion 5c of the through hole 5 is provided with a spring. Insert 9.

The core control device 20 presses the wedge-shaped cores 2 and 2'by the spring 9 so that the wedge-shaped cores 2 and 2'are tapered as the core cores 1 are separated as shown in FIG. 1 and slides to the tapered side of the inclined surfaces 1a and 1b, the small diameter portion 5a of the through hole 5 is locked to the rod head 8a,
The core core 1 and the core core 1 are separated as shown in FIG. As the wedge-shaped cores 2 and 2'slide toward the tapered sides of the core core inclined surfaces 1a and 1b, the wedge-shaped cores 2 and 2'approach each other toward the center of the front male die A1, and the wedge-shaped cores 2 and 2 ' The outer peripheral surface 2b of the'is released from the molded product D.

The side cores 3 are wedge-shaped cores 2 and 2 arranged on the front sloped surface 1c of the core core 1 and the left and right inclined surfaces 1a and 1b of the core core 1.
'The inner slope 3a that is in contact with the front slope 2c and the front male type
Due to the outer peripheral surface 3b with the center of A1 as the fulcrum, it becomes thinner from the tip toward the rear end, and has a substantially semi-cylindrical shape.
Is the front slope 1c of the core core 1 and the front slope of the wedge-shaped cores 2, 2 '.
2c is formed at the same angle, the outer peripheral surface 3b is formed concentric with the wedge-shaped cores 2 and 2 ', and an undercut 13 continuous with the undercut 12 of the wedge-shaped cores 2 and 2'is formed on the outer peripheral surface 3b. ing.

The side core 3'is symmetrical to the side core 3 and will not be described. Both side cores 3, 3
'Is moved toward the center of the front male mold A1 by the sub-cylinder P2 as shown in FIG. 11 after the core 1 and the wedge-shaped cores 2 and 2'are separated, approaching each other, and the outer periphery of the side cores 3 and 3'. surface
3b is released from the molded product D. The molded product D is injected by the mold release of the side cores 3 and 3 ', and is separated and returned after the molded product D is injected.

Inclination angle θ of the core core inclined surfaces 1a and 1b and the through hole 5
The large-diameter portion length L on the front side of the wedge-shaped cores 2, 2'undercut 12 and the side cores 3, 3'undercut 13
It is formed according to the size of the core core inclined surface 1a, 1b
As the inclination angle θ of the wedge-shaped cores 2 and 2 ′ is increased, the entrance / exit dimension T of the wedge-shaped cores 2 and 2 ′ can be increased, and as the length L of the large diameter portion on the front side of the through hole 5 is increased / decreased. The dimension T can be increased.

Pins 6 are provided on the front ends of the front and rear slopes 2c and 2d of the wedge-shaped core 2, and pins 16 are also projected on the front and rear slopes 2c and 2d of the wedge-shaped core 2 ', and the inner slope 3a of the side cores 3 and 3'is Wedge-shaped cores 2 and 2
It is desirable to form the hook-shaped grooves 7 and 17 into which the pins 6 and 16 of '1 are inserted respectively. The hook-shaped grooves 7 and 17 are formed by a horizontal portion 7a parallel to the mold clamping direction, and the wedge-shaped cores 2 and 2 from the tip of the horizontal portion 7a.
'' Consists of a vertical part 7b that bends in and out, and a horizontal part 7a.
Is formed on the inner slope 3a of the side cores 3, 3 ', so that it becomes shallower toward the rear end from the front end. The pins 6 and 16 of the wedge-shaped cores 2 and 2'are guided along the vertical portion 7b of the hook-shaped grooves 7 and 17 as the core core 1 reciprocates, and the wedge-shaped cores 2 and 2'are
When it is detached together, it is guided along the horizontal portion 7a of the hook-shaped grooves 7,17.

Since the injection molding die according to the present invention has the above-mentioned structure, the front male die A1 and the rear male die A2 are combined, and the female die B1 and B2 are combined as shown in FIG. In this state, the wedge-shaped cores 2 and 2 ′ are located on the rear end side of the core core 1, and the side cores 3 and 3 ′ are the front slopes 1c and 2c and the rear slope 1d of the core core 1 and the wedge-shaped cores 2 and 2 ′. Outer peripheral surface 2b of wedge-shaped cores 2 and 2'having an undercut 12 and having a face-to-face contact over 2d
Then, the cavity C is formed by the outer peripheral surfaces 3b of the side cores 3, 3'having the undercuts 13.

After the molten resin is injected into the cavity C and the molten resin is solidified, the core core 1 is first retracted as shown in FIG. 9, so that the wedge-shaped cores 2 and 2 ′ extend along the left and right inclined surfaces 1 a and 1 b of the core core 1. It becomes slidable and the spring 9 of the core controller 20
Since the core core 1 is pressed against the front side of the core core 1, the core core 1 is retracted leaving the wedge-shaped cores 2 and 2 ', and the wedge-shaped cores 2 and 2'are slid to the front side with the retraction. That is, the wedge-shaped cores 2, 2'approach each other toward the center of the front male mold A1 and are released from the molded product D.

When the wedge-shaped cores 2, 2'are completely released from the molded product D, the rod head 8a of the core control device 20 is locked to the through-hole small-diameter portion 5a of the wedge-shaped cores 2,2 '. It is released from the molded product D together with the retracting core 1. After the core core 1 and the wedge-shaped cores 2 and 2'are released from the molded product D, the sub cylinder P2
Then, the side cores 3 and 3'approach toward each other toward the center of the front male mold A1, and when completely separated from the molded product D, they are released from the molded product D.

At the front of the front slope 1c and the rear slope 1d of the core core 1,
As shown in FIG. 3, a stepped recess 21 is provided which bites toward the center, and the front ends of the front slope 2c and the rear slope 2d of the wedge-shaped cores 2 and 2'are aligned with the step recess 21 of the core 1 as shown in FIG. Stepped recesses 22 are provided respectively, and, on the contrary, the inner slope 3a of the side cores 3, 3 '
As shown in FIG. 7, if a convex portion 23 that engages with the stepped recessed portion 21 of the core 1 and the stepped recessed portion 22 of the wedge-shaped cores 2 and 2 is provided at the front end of the core core, the front male type It is easy to insert and remove A1.

In FIG. 12A, guide grooves 14 in the form of dovetail grooves are provided on the inclined inner surfaces 2a of the wedge-shaped cores 2 and 2 ', and the dovetail guide grooves 14 are fitted to the right and left inclined surfaces 1a, 1b of the core core 1. Ant ridge 4 to insert
Are provided so that the reciprocating motions of the wedge-shaped cores 2 and 2'are made more stable. In FIG. 12B, dovetail-shaped guide grooves 14 and 24 are provided on the left and right inclined surfaces 1a and 1b of the core 1 and the inclined inner surfaces 2a of the wedge-shaped cores 2 and 2 ', respectively. The dovetail ridge 4 is inserted into one side.

The injection molding die according to the present invention is not limited to the above-mentioned embodiment, and for example, the female dies B1 and B2 can be released before and after the retraction of the core 1. However, it is also possible to perform it before and after the side cores 3 and 3'are retracted. Further, even if the ridges 4 of the core core 1 and the guide grooves 14 of the wedge-shaped cores 2 and 2'are provided opposite to each other, the same purpose can be achieved, and the core core 1 and the wedge-shaped core 2, which form the front male mold A1, can be achieved. 2 ', the side cores 3 and 3', and the shape and structure of the core control device 20 can be appropriately changed without departing from the scope of the present invention.

[0024]

Since the injection molding die according to the present invention has the above-mentioned structure, it has the following effects. At least one of the front male mold and the rear male mold constituting the male mold,
It is composed of a pyramid-shaped core core, wedge-shaped cores arranged on the left and right inclined surfaces of the core core, and side cores that face the front and rear slopes of both cores, and the wedge-shaped core slides toward the front side when the core core is removed. Since the side core approaches the center side of the male mold after being separated together with the core core, a large undercut molded product can be injection-molded accurately and reliably.

At least one of the front male part and the rear male part is divided, but the number of divisions is the minimum, and the wedge-shaped cores arranged on the left and right inclined surfaces of the core core have a symmetrical shape. Since the side cores that come into contact with the front and rear slopes of the wedge-shaped core also have a symmetrical shape, not only the manufacturing is simple and the drilling of cooling water holes is easy, but also the disassembling and assembling of the mold is remarkably easy, and the cost is low. obtain. Furthermore, since the side core is released after the core core and the wedge-shaped core are separated, the molten resin rarely infiltrates between the cores and solidifies. Even if the molten resin infiltrates and solidifies between the cores, the side core Can be easily removed in the mold release state.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a structural example of an injection molding die according to the present invention.

FIG. 2 is a cross sectional view thereof.

FIG. 3 is an exploded perspective view showing a structural example of a front male type.

4A and 4B are a vertical sectional view and a plan view of the wedge-shaped core of FIGS.

5A and 5B are a front view and a plan view of a wedge-shaped core provided with (A) and (B) engaging portions.

6A and 6B are a plan view and a front view of (A) and (B) of the side core.

FIG. 7 is a plan view of a side core provided with an engaging portion.

FIG. 8 is a sectional view of (A) and (B) in a mold clamped state.

FIG. 9 is a sectional view of (A) and (B) when the core core is retracted.

10 (A) and (B) are a cross-sectional view of the core core and the wedge-shaped core at the time of mold release, and a front view of the core core.

FIG. 11 is a cross-sectional view showing a mold release example of the side cores (A) and (B).

FIG. 12 is a front view showing a fitting structure example of (A) and (B) core cores and wedge-shaped cores.

[Explanation of symbols]

1 core, 1a, 1b inclined surface 2, 2'wedge-shaped core, 2a inclined inner surface, 1c, 2c front inclined surface,
1d, 2d rear slope 3, 3'side core, 3a inner slope, 2b, 3b outer peripheral surface 4 ridge 5 through hole 6, 16 pin 7, 17 hook groove 8 rod 9 spring 11 movable plate, 12, 13 undercut 20 Core control device, 21, 22 stepped recess, 23 raised part, 1
4,24 Guide groove A1 front male mold, A2 rear male mold B1, B2 female mold D molded product, C cavity P1 main cylinder, P2 secondary cylinder L length of large diameter part of through hole, T wedge core Ingress / egress dimensions θ Angle of inclination of core core inclined surface

Claims (2)

[Claims] 1. A pyramidal core (1) having at least one of a front male mold (A1) and a rear male mold (A2) constituting a male mold, and a left and right inclined surface (1a, 1b) wedge-shaped cores (2, 2 '), side cores (3, 3') arranged across the front slopes (1c, 2c) and the rear slopes (1d, 2d) of the core core and the wedge-shaped cores. ) And the undercut (1b) on the outer peripheral surface (2b) of the wedge-shaped core and the outer peripheral surface (3b) of the side core.
2 and 13) are provided continuously so that the wedge-shaped core can be guided and slid along the inclined surface of the core core, while the wedge-shaped core is attached to the male mold movable plate (11) when the core core is removed. Provided with a core control device (20) that slides toward the tip side and separates together with the core.
In addition, an injection molding die in which the side cores can approach each other after the core core and the wedge-shaped core are separated. 2. Left and right inclined surfaces (1a, 1b) of the core (1)
And one of the slanted inner surfaces (2a) of the wedge-shaped cores (2, 2 ') facing the slanted surface, the ridge (4) parallel to the slanted inner surface (2a).
On the other side, a guide groove (14) to be inserted into the ridge is provided so that the wedge-shaped core can be guided and slid along the inclined surface of the core,
The wedge-shaped core is provided with a through hole (5) parallel to the inclined inner surface (2a), and the core control device (20) is attached to the male mold movable plate (1).
1) A rod (8) inserted and locked in the through hole of the wedge-shaped core
And a spring (9) for pressing the wedge-shaped core to the tapered side of the core, the injection molding mold according to claim 1.