JPH05253978A - Injection mold - Google Patents

Abstract

PURPOSE:To enable molding of a through hole of an undercut part of a molded product without causing a mold trouble or flashes to be generated. CONSTITUTION:The title mold is comprised by providing with a slide core 4 provided with a tilted part 9 whose slope is faced in a mold release direction, a core pin 5 in which a return pin 12 wherein it possesses a tilted part 10 whose slope is faced in an antimold release direction by corresponding to the tilted part 9, its one end is provided with a protrusion 11 and the other end is fitted with a spring 13 is screwed and a core 3 which supports the spring 13 and is provided with a spring pad part 18 through which the return pin 12 is penetrated.

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 an undercut portion.

[0002]

2. Description of the Related Art In a molded product having a through hole, the pins are protruded from both the core and the cavity so that the push-cut surfaces of the pins are butted against each other with a slight gap, or the push-cut surface of the core pin is So that it touches the inner surface of the cavity,
Alternatively, it is injection-molded by using a mold in which the core pin is projected from the core so that there is a slight gap. The mold in which the core pin is protruded from the core is, for example, as shown in FIG. 3, when the molded product 1 has an undercut portion 22,
The slide core 24 is reciprocated in the X arrow direction so that the undercut portion 22 can be released from the mold, and the core pin 25 is moved from the core 23 to the push-cut surface 7 of the slide core 2.
The through hole 6 is formed so as to project so as to come into contact with the molding surface 8 of No. 4. Reference numeral 21 is a cavity.

[0003]

By the way, the molded article 1 is
As shown in FIG. 4, after the slide core 24 is actuated and slid in the Y arrow direction to allow the undercut portion 22 to be released from the mold, the slide core 24 is ejected in the Z arrow direction by an ejection pin or the like to be released from the die. However, when the slide core 24 slides in the direction of the arrow Y, the push-cut surface 7 of the core pin 25 is rubbed because the core pin 25 is fixed.
In this case, mold troubles such as surface sagging tended to occur and the core pin 25 was damaged in some cases. Further, in order to prevent the sagging of the push-cut surface 7 and the damage of the core pin 25, when a gap is provided between the push-cut surface 7 of the core pin 25 and the molding surface 8 of the slide core 24, a through hole formed Bali to 6,
There is a problem that burrs are likely to occur.

In view of the above points, it is an object of the present invention to provide an injection molding die capable of molding a through hole in an undercut portion of a molded product without causing mold troubles or burrs. And

[0005]

SUMMARY OF THE INVENTION An injection molding die according to the present invention comprises a slide core provided with an inclined portion whose inclined surface faces in the releasing direction, and the inclined surface corresponding to the inclined portion. A core pin having an inclined portion facing the mold direction, one end provided with a protrusion, and the other end screwed with a return pin having a spring attached thereto, and a spring receiving portion supporting the spring and penetrating the return pin. And a core provided with.

[0006]

When the mold is opened, the core pin is pulled back by the force of the spring attached to the return pin that is screwed to the core pin as the slide core slides, and the push-cut surface of the core pin is separated from the molding surface of the slide core. Be done. When the mold is closed, the slid part of the core pin pushes the slant part of the core pin against the slant part of the slide core, the core pin moves against the force of the spring, and the push-cut surface of the core pin abuts the molding surface of the slide core. To be done. This prevents the push-cut surface of the core pin from being rubbed by the slide core when the mold is opened and closed, and prevents the push-cut surface of the core pin from being out of order and the core pin from being damaged.

[0007]

EXAMPLES Examples will be described below with reference to the drawings. FIG. 1 is a partial sectional view of an embodiment of the injection molding die of the present invention when the die is closed. Reference numeral 1 is a molded product having an undercut portion 2 and provided with a through hole 6, 3 is a core, 4 is a slide core, 5 is a core pin, and 20 is a cavity. The lower side surface of the slide core 4 is provided with an inclined portion 9 whose inclined surface faces in the mold release direction (D arrow direction). On the lower side surface of the core pin 5, there is provided an inclined portion 10 having an inclination angle corresponding to the inclination angle of the inclined portion 9 and an inclined surface facing in the releasable direction (arrow B direction). The surface opposite to the surface having the inclined portion 10 is a sliding surface 15 that slides on the side surface 14 of the core 3. Molded product 1 of core pin 5
A protrusion 11 that forms the through hole 6 of the molded product 1 is provided on the side, and a return pin 12 having a spring 13 attached thereto is screwed on the opposite side. The core 3 is provided with a spring receiving portion 18 which supports the spring 13 and through which the return pin 12 penetrates. Further, the core 3 is provided with a recess 17 so that the core pin 5 can reciprocate.
And the spring receiving portion 18 is provided at the bottom of the recess 17. The depth of the recess 17 is appropriately determined according to the shapes of the slide core and the slide pin.

FIG. 2 is a partial sectional view of the mold of FIG. 1 when the mold is opened. When the slide core 4 operates from the state of FIG. 1 and slides in the direction of the arrow A, the inclined portions 9 and 10 are separated,
The core pin 5 slides in the direction of arrow B by the spring 13 and is pulled back until it comes into contact with the spring receiving portion 18 provided at the bottom of the recess 17 of the core 3. The pullback operation in the arrow B direction is started together with the movement of the slide core 4 in the arrow A direction, so that the push-cut surface 7 of the core pin 5 is not rubbed by the slide core 4. As a result, the sagging of the push-cut surface 7 of the core pin 5 and the damage of the core pin 5 are prevented. When the mold is clamped, the operation opposite to that when the mold is opened is performed. When the slide core 4 is actuated to slide the slide core 4 in the direction of the arrow C, the slanted portion 9 of the slide core 4 is pressed against the slanted portion 10 of the core pin 5, whereby the core pin 5 is resisted against the force of the spring 13. Is slid in the direction of the arrow D. The slide core 4 is slid further, and the mold clamping by the slide core 4 is completed in a state where the push-cut surface 7 of the core pin 5 is in contact with the molding surface 8 of the slide core 4.

[0009]

Since the push-cut surface of the core pin is not rubbed by the slide core when the mold is opened and closed, the sagging of the push-cut surface of the core pin and the damage of the core pin can be prevented. Since the through hole can be formed without providing a gap between the pressing surface of the core pin and the molding surface of the slide core, it is possible to prevent the occurrence of burrs and burrs in the through hole. As a result, the through hole in the undercut portion of the molded product can be molded without causing mold troubles and burrs.

[0010]

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an embodiment of an injection molding die of the present invention when a die is closed.

FIG. 2 is a partial cross-sectional view of the mold of FIG. 1 when the mold is opened.

FIG. 3 is a partial cross-sectional view of a conventional injection molding mold when the mold is closed.

FIG. 4 is a partial cross-sectional view of the mold of FIG. 3 when the mold is opened.

[0001]

[Explanation of symbols]

 1 Molded product 2,22 Undercut part 3,23 Core 4,24 Slide core 5,25 Core pin 6 Through hole 7 Push-off surface 8 Molding surface 9,10 Inclined part 11 Protrusion 12 Return pin 13 Spring 14 Side surface 15 Sliding surface 17 Recessed portion 18 Spring receiving portion 20, 21 Cavity

Claims (1)

[Claims] 1. A slide core in which an inclined surface is provided with an inclined portion facing in a releasing direction, and an inclined portion corresponding to the inclined portion has an inclined portion facing in a releasing direction, and a protrusion is provided at one end. And a core pin to which a return pin having a spring attached at the other end is screwed, and a core provided with a spring receiving portion that supports the spring and through which the return pin penetrates are provided. Mold for injection molding.