JPH09155930A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the removal of the undercut part by providing a wedge- like protrusion at the lower part of the laterally moving cam of an overhead core and a slide surface at the movable side mold core corresponding to the protrusion, laterally movably mounting the lower end of the overhead core at a lifting plate, and always urging the cam side by a spring. SOLUTION: When the molding is finished, a movable side mold core 2 descends, but a lifting plate 7 does not move. An overhead core 3 protrudes from the core 2 to release a molding 4 from the core 2. Further, when the core descends, a laterally moving cam 9 rides on a slide surface 10, and a wedge-like protrusion 11 simultaneously rises on a slide surface 12. As a result, the core 3 is urged by the surfaces 10, 12 to move in parallel with the rightward direction. In this case, a lifting pin 6 also moves rightward while compressing a spring 8 in a long hole. Thus, since the core 3 is not rotated but moves rightward in parallel, the undercut part 5 can be smoothly released. Further, when the core 2 descends, the plate 7 and core 3 descend as well, thereby removing the molding 4.

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, and more specifically, a mold incorporating a straight-up type core for molding a molded article having an undercut. Is related to the structure of.

[0002]

2. Description of the Related Art In injection molding, when a molded product has an undercut, a die structure such as a forced drawing type, a slide core type, or a split type is adopted, but a straight-up type core is often incorporated. is there.

A conventional example of a mold structure incorporating a direct-up core is described with reference to FIG. FIG. 2 is a cross-sectional view of an injection molding die, (a) is a cross-sectional view of a main part showing a state in which the die is closed,
FIG. 6B is a cross-sectional view of essential parts showing a state where the mold has started to open and the undercut portion has come off. The cavity is surrounded by the fixed-side template 1, the movable-side core 2, and the straight-up core 3 ′, and the undercut portion 5 of the molded product 4 is molded at the tip portion of the straight-up core 3 ′. The lower end of the straight-up core 3'is attached to the push-up plate 7 by the push-up core 6.

Molding is performed with this mold, and when the molding is completed,
The mold begins to open and the core 2 descends. At this time, since the push-up plate 7 has not moved yet, the molded product 4 is pushed out of the core 2 by the straight-up type core 3'and released from the mold, as shown in FIG. 2 (b). At the same time, the lateral-moving cam 9 of the straight-up core 3 ′ hits the lateral-cam sliding surface 10 of the core 2, and the straight-up core 3 ′ rotates to the right in the figure with the push-up core 6 as a fulcrum, thereby causing an undercut portion. 5 disengages from the straight-up core 3 '. After that, the push-up plate 7 also begins to retract, and the molded product 4 is taken out of the mold.

[0005]

However, in the above mold, when the direct-up core 3 is pushed out of the movable core 2 when the die is opened, as shown in FIG. The lateral movement cam 9 is in contact with the lower end of the lateral movement cam sliding surface 10 at one point, and is in contact with the upper end of the core 2 at one point on the opposite side, and the lower end of the straight-up core 3 is a push-up core. Since it is rotatably fixed to the push-up plate 7 by 6,
The straight-up core 3 is not parallel to the sliding surface of the movable core 2 and slides in a slightly inclined state. The same applies when the mold is closed.

As a result, the movement of the straight-up core 3'is not smooth when the mold is opened and closed, and in some cases so-called kinking occurs and the direct-up core 3'cannot operate.
Also, since the tip of the straight-up core 3'moves in an arc,
The undercut portion 5 may not be removed smoothly, and the molded product 4 may be damaged or whitened. Further, there are drawbacks that the bending force is applied to the straight-up type core 3'to be deformed and sufficient durability cannot be maintained. In the present invention, such a defect is eliminated, and the direct-up core moves parallel to the moving direction of the mold on the movable side at a right angle, facilitating the removal of the undercut portion, and at the same time, extruding the direct-up core. Also provides a mold for the purpose of performing smoothly.

[0007]

In order to achieve the above object, an injection molding die of the present invention is a molding die in which a straight-up core is incorporated. In addition to providing a wedge-shaped projection on the lower part of the, the sliding surface is provided on the movable side mold core corresponding to this wedge-shaped projection, and the lower end of the straight-up type core is attached to the push-up plate so that it can move laterally The feature is that the cam is always pressed toward the dynamic cam.

In the present invention, the straight-up type core means a core that operates in the same direction as the operating direction of the push-up plate. Also,
The wedge-shaped projection has almost the same height as the traverse cam, and at the same time as the traverse cam rides on the sliding surface, or slightly later,
The wedge-shaped protrusion must also be provided at a position to ride on the sliding surface. It is needless to say that when the lateral movement cam is operated, there must be a gap between the opposite surface of the straight-up core and the die core so that the straight-up core can laterally move.

The lower end of the straight-up type core is attached to the push-up plate by a push-up core, but the push-up core must be mounted on the push-up plate so as to be able to move laterally through an elongated hole or the like.
A spring is attached to the side surface of the push-up core so that the push-up core is constantly pressed toward the lateral movement cam.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an injection molding die of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing an example of an injection molding die of the present invention.
Is a cross-sectional view showing a state where the mold is closed, (b) is a cross-sectional view showing a state before the mold is opened, the movable-side mold core starts to descend, and the lateral movement cam of the direct-up core is activated, (c) FIG. 4 is a cross-sectional view showing a state in which a lateral movement cam of a straight-up type core has operated.

The cavity is surrounded by a fixed side mold plate 1, a movable side mold core 2 and a straight-up type core 3, and an undercut portion 5 of a molded product 4 is molded at the tip of the straight-up type core 3. . The lower end portion of the straight-up type core 3 is attached to a push-up plate 7 by a push-up core 6 through a long hole so that the push-up plate 7 can move in the lateral direction in the drawing. A spring 8 is mounted on the right side of the push-up core 6, and the push-up core 6, that is, the lower end portion of the straight-up core 3 is always pressed in the left direction in the drawing. Reference numeral 9 is a lateral movement cam, 10 is a sliding surface thereof, 11 is a wedge-shaped projection, and 12 is a sliding surface thereof.

When the molding is completed in the state of FIG. 1 (a), the movable die core 2 descends, but the push-up plate 7 does not move, so that the straight-up type core 3 projects from the movable die core 2. The molded product 4 is released from the movable mold core 2. Then, when the movable-side mold core 2 is further lowered, the lateral movement cam 9 rides on the sliding surface 10, and at the same time, the wedge-shaped projection 11 also rides on the sliding surface 12, as shown in FIG. 1 (c). As a result, the straight-up core 3 is pressed by the sliding surfaces 10 and 12 and moves in parallel to the right. At that time, the push-up core 6 also moves to the right while compressing the spring 8 in the elongated hole. In this way, the tip end portion of the straight-up core 3 does not rotate but moves in parallel to the right, so that the undercut portion 5 can be smoothly separated.

Further, when the movable mold core 2 descends, the push-up plate 7 also begins to descend and the direct-up core 3 also descends to take out the molded product 4. For subsequent molding, the mold begins to close, but the process is the reverse of when the mold is opened. Lateral cam 9
When the wedge-shaped protrusion 11 comes off the sliding surface 10 or 12,
The inclined surface 13 on the right side of the straight-up core 3 is pushed by the die core surface, and the spring 8 causes the straight-up core 3 to move in parallel to the left and return to its original position.

[0014]

As described above, when the injection molding die of the present invention is used, when the direct-raising type core operates,
Since the push-up core is moved laterally by being pressed by the sliding surface of the lateral cam and the sliding surface of the wedge-shaped projection, the straight-up type core moves in parallel instead of rotating, so that the opposite side of the straight-up type core is also movable. It is supported by the surface of the mold core, and the sliding between the direct-up core and the surface of the movable-side mold core becomes extremely smooth, and the direct-up core does not bend. Further, the undercut portion can be easily released, and defects such as scratches and whitening are reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an example of a mold for injection molding of the present invention, (a) is a cross-sectional view showing a state in which the mold is closed, and (b) is a mold core on the movable side when the mold is opened. Is a cross-sectional view showing that the horizontal movement cam has not started yet,
(C) is a sectional view showing a state in which the lateral movement cam is operated.

FIG. 2 is a cross-sectional view showing an example of a conventional injection-molding die incorporating a straight-up core, wherein (a) is a main-portion cross-sectional view showing a closed state of the die, and (b) is a die. It is sectional drawing which shows the state which started opening.

[Explanation of symbols]

 1 Fixed Side Mold Plate 2 Movable Side Mold Core 3, 3'Directly Raised Core 4 Molded Product 5 Undercut Part 6 Push Up Core 7 Push Up Plate 8 Spring 9 Traverse Cam 10 Traverse Cam Sliding Surface 11 Wedge Protrusion 12 Wedge Shape Sliding surface of protrusion 13 Sloping surface

Claims (1)

[Claims] 1. A molding die incorporating a straight-up core, wherein a wedge-shaped projection is provided at a lower portion of a lateral movement cam of the straight-up core, and the movable-side mold core is provided with the wedge-shaped projection in correspondence with the wedge-shaped projection. A sliding surface is provided, and the lower end of the straight-up core is
An injection molding die characterized in that it is attached to a push-up plate so as to be able to move laterally, and is constantly pressed to the side-moving cam side by a spring.