JPH08183071A - Mold device - Google Patents

Abstract

PURPOSE: To obtain a molded piece having a good appearance without a gate remaining in the molded piece by a method wherein a top of a core pin is disposed movably forward and backward at a gate port part between a top of a runner for flowing a resin and an inlet of a cavity part for molding the resin into a molded piece, and the gate port part is closed with the core pin positioned at the forward position. CONSTITUTION: A mold device is closed, and a resin is charged into a cavity part 112 between a cavity plate and a core pin 9. At this time, an inner core pin 11 is disposed so that a reduced-diameter part 11d is positioned at a gate port part 3. A resin is charged into the cavity part 112 through a gap between the reduced-diameter part 11d and the gate port part 3. After that, by moving the inner core pin 11 forward by an air cylinder, an intermediate part 11d of the inner core pin 11 is fitted into the gate port part 3 to block the gate part 3. Simultaneously, a gate 113 is cut, and a runner 111 is separated from a molded piece. After completion of molding, the molded piece is discharged from a core pin 9 by opening the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold apparatus for injection molding or the like in which a gate opening is provided between a runner section through which a resin flows and a cavity section in which a molded product is molded. .

[0002]

2. Description of the Related Art An example will be described with reference to FIGS.
Inside the cavity plate 101, a cavity portion 102 for molding a molded product is formed. A gate opening 103 and a runner 104 are formed in front of the cavity 102 (hereinafter, the left direction in the drawing is referred to as the front). The runner portion 104 is composed of a vertical runner portion and a horizontal runner portion. In front of the cavity plate 101, a runner stripper plate 105 that discharges the runner after molding is attached. A fixed plate 106 fixed to the molding machine is attached to the front of the runner stripper plate 105. A runner lock pin 107 for temporarily holding the runner is fixed to the fixed plate 106.

On the other hand, behind the cavity plate 101 is a core plate 110 to which a stripper plate 108 for ejecting a molded product from a core pin described later after molding and a core pin 109 for forming a cavity in the molded product are fixed.
Is attached. The tip of the core pin 109 is adapted to be inserted into the holding hole formed in the cavity plate 101 in the 101a. This is to prevent bending of the core pin due to resin pressure or the like.

Next, the operation will be described. FIG. 11 shows a state where the mold device is closed and the resin is flowing into the cavity portion 102. At this time, the core pin 109 is not bent by the pressure of the resin because the tip of the core pin 109 is fitted into the holding hole 101a as described above. FIG. 12 shows a state when the mold device is opened. The runner 111 and the molded product 112 are torn off from the gate 113, and the runner 111 is attached to the runner lock pin 107.
The molded product 112 is held by the core pin 109. FIG.
3 is a state in which the mold is further opened. The runner 11
In No. 1, the runner lock pin 107 is discharged by the runner stripper plate 105, and the molded product 112 is discharged from the core pin 109 by the stripper plate 108.

[0005]

However, in the above-mentioned conventional technique, the gate remains at the location where the runner and the molded product are separated. Although these gates are minute projections, they are conspicuous especially for small molded products and significantly impair the appearance. In addition, in the case of a molded product that can be touched by the hand, the gate touches a finger or the like, which causes pain and discomfort, and if it is strong, the finger or the like may be scratched, which is dangerous.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a core pin is provided at a gate opening portion between a tip of a runner portion through which a resin flows and an inlet portion of a cavity portion where a molded product is formed. It is characterized in that the tip is disposed so as to be able to move back and forth, the resin flows into the cavity from the outer periphery of the core pin at the retracted position, and the gate opening is closed at the advanced position.

[0007]

[Function] The core pin is arranged in the gate opening so as to be able to move back and forth, the core pin is positioned so that there is a gap between the outer circumference of the tip of the core pin and the gate opening, and the resin flows from the outer circumference of the core pin into the cavity. After the inflow is completed, the core pin is moved forward to block the gate opening and the cavity.

[0008]

(Embodiment) A first embodiment will be described with reference to FIGS. 1 to 4. Inside the cavity plate 1, a cavity portion 2 for molding a molded product is formed. A conical gate opening 3 is formed in front of the cavity 2. A runner plate 5 having a runner portion (hole) 4 is attached to the front of the cavity plate 1, and a runner stripper plate 6 for ejecting the runner after molding is attached to the front of the runner plate 5. ing. A fixed plate fixed to the molding machine is attached to the front of the runner stripper plate 6, and a runner lock pin 7 for temporarily holding the runner is fixed to the fixed plate. On the other hand, behind the cavity plate 1, there is fixed a molding machine, a stripper plate 8 for discharging a molded product from a core pin described later, and a hollow core pin 9 for forming a hollow portion in the molded product. A plate 10 is attached. Inside the hollow core pin 9, a middle core pin 11 is slidably arranged.
The rear end 11a of the middle core pin 11 is located behind the core plate 10 and moves back and forth.
It is fixed to 2. Further, the intermediate portion 11b of the middle core pin 11 is formed to have the same diameter as the diameter of the gate opening portion 3, and the conical tip portion and the reduced diameter portion 11d are provided in front of the intermediate portion 11b via the conical portion 11c. 11e is formed. Reference numeral 13 is a rod of an air cylinder for moving the middle core plate 12. As means for moving the middle core plate 12, an appropriate means such as one using gear drive or opening / closing operation of die is adopted. it can.

Next, the operation will be described. The mold device is closed and resin is poured into the cavity portion 2. At this time, the position of the middle core pin 11 is adjusted so that the reduced diameter portion 11d is located at the gate opening portion 3 as shown in FIG. To place. By thus forming a gap between the reduced diameter portion 11d and the gate opening portion 3, the resin is poured into the cavity portion 2 through this gap. Next, after the resin is poured into the cavity 2 part, the air cylinder 13 is operated and the middle core pin 11 is advanced. By the forward movement of the middle core pin 11, the middle portion 11b of the middle core pin 11 is fitted into the gate opening portion 3 and the gate opening portion 3 is completely closed (see FIG. 3 and FIG. 4 which is an enlarged view of the main part of FIG. 3). ). By this operation, the gate 113 is cut and the runner 111 and the molded product 112 are separated. After the completion of molding, when the mold is opened as in the prior art, the runner 111 and the molded product 112 are discharged from the runner plate 5 and the core pin 9 by the runner stripper plate 6 and the stripper plate 8, respectively. Finally, the air cylinder 13 is returned.

A second embodiment will be described with reference to FIGS. 5 and 6.
The configuration that is particularly different from the first embodiment is the shape of the front portion of the core pin 14. The conical tip portion 14a is formed by continuously connecting without forming the reduced diameter portion as in the previous example. Then, at the time of molding (when the resin is poured into the cavity), the conical tip portion 14a is positioned at the gate opening 3. Thus, the conical tip 14
By arranging a in the gate opening 3, the position can be easily changed, and therefore, the area of the gap formed between the tip portion 14a and the gate opening 3 can be easily changed, so that The amount of resin flowing in can be easily changed.

A third embodiment will be described with reference to FIGS. 7 and 8.
The configurations that are particularly different from the first and second embodiments are the shape of the front portion of the core pin 15 and the setting position with respect to the gate opening 3. In the front of the core pin 15 in this embodiment, a plurality of vertical grooves 15a are formed in the circumferential direction. Then, at the time of molding, the gate opening 3 is fitted to the portion where the vertical groove 15a is formed. The resin flows into the cavity 2 through the vertical groove 15a.
In this embodiment, since the core pin 15 is fitted into the gate opening 3 when the resin flows in, it is possible to prevent the core pin 15 from bending due to the pressure of the resin. In this embodiment, the resin is poured into the cavity from a plurality of points, so that the resin may be different from that shown in FIG.
As shown in FIG.
(Generally called weld) may occur, but in the first and second embodiments, no weld is generated because the resin is poured from the circumferential direction. Although an example of forming a cylindrical object has been described above, FIG. 9 may be a box body 116 having a hole 116a in the fourth embodiment of the present invention, and FIG. 10 is a fifth embodiment of the present invention. It may be a flat plate 117 having holes 117a.
That is, a molded product having at least one hole may be used.

[0013]

According to the present invention, the tip of the core pin is disposed so as to be able to move back and forth at the gate opening between the tip of the runner portion through which the resin flows and the entrance of the cavity portion where the molded product is formed.
At the retracted position, the resin flows into the cavity from the outer periphery of the core pin, and at the advanced position, the gate opening is closed.
It is possible to provide a molded product which is excellent in safety without leaving a gate in the molded product and in which no weld (resin joint) is formed and which has a beautiful appearance.

[Brief description of drawings]

FIG. 1 is a front sectional view at the time of injection according to a first embodiment of the present invention.

FIG. 2 is an enlarged front sectional view of the gate opening portion of FIG.

FIG. 3 is a diagram when the core pin of FIG. 1 is advanced and the gate opening is closed.

FIG. 4 is an enlarged front sectional view of the gate opening portion of FIG.

FIG. 5 is a front sectional view at the time of injection molding of the second embodiment of the present invention.

6 is a front cross-sectional view when the core pin of FIG. 5 is advanced and the gate opening is closed.

FIG. 7 is a front sectional view of the third embodiment of the present invention during injection molding.

FIG. 8 is a sectional view taken along the line AA of FIG.

FIG. 9 is a front sectional view of a fourth embodiment of the present invention.

FIG. 10 is a front sectional view of a fifth embodiment of the present invention.

FIG. 11 is a front cross-sectional view at the time of injection molding of the related art.

FIG. 12 is a diagram when the mold of FIG. 11 is opened.

13 is a front sectional view of the molded product shown in FIG. 12 taken out.

FIG. 14 is an external perspective view of a molded product produced by a conventional device.

[Explanation of symbols]

 1 cavity plate 2 cavity part 3 gate opening part 4 runner part 5 runner plate 6 runner stripper plate 7 runner lock pin 9 core pin 10 core plate 11 middle core pin 11a rear end of middle core pin 11b middle part of middle core pin 11c middle core pin Conical portion 11d Medium core pin reduced diameter portion 11e Medium core pin tip portion 12 Medium core plate 14 Core pin 14a Core pin tip portion 15 Core pin 15a Vertical groove

Claims (1)

[Claims] 1. A gate port between a tip of a runner part through which a resin flows and an inlet of a cavity part where a molded product is formed,
A mold device in which the tip of the core pin is arranged so that it can move back and forth, resin flows into the cavity from the outer periphery of the core pin at the retracted position, and the gate opening is closed at the advanced position.