JP2002234061A - Stack mold and method for manufacturing injection molding using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack mold capable of stably manufacturing injection moldings of the same shape in a large quantity with good productivity and a method for manufacturing the injection moldings using the same. SOLUTION: The stack mold comprises a first sprue bush 11 having a first sprue 11 for communicating with a first cavity C1 through a first rubber R1 at an inner periphery and provided at a fixed side mold plate 1, a second sprue bush 21 having a second sprue 211 for communicating with a second cavity C2 through a second runner R2 at an inner periphery and provided at an intermediate mold plate 2, and a slide core 24 provided adjacent to the second bush 21. At the mold opening or closing time, the core 24 is set slidable in association with a movement of the plate 2. At the mold opening time, the second bush 21 is set extrudable to the plate 1 side in cooperation with sliding of the core 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stack mold for mass-producing injection moldings of the same shape such as pipe joints, gutter parts, OA parts, etc. with high productivity, and production of injection moldings using the same. It is about the method.

[0002]

2. Description of the Related Art Conventionally, a stack mold includes a fixed mold plate, a movable mold plate, and an intermediate mold plate provided therebetween, and a mold for fixing a runner to the mold plate is provided. Engrave the resin puddle in the undercut shape on the open side,
In general, a method is adopted in which a sprue and a runner in an intermediate mold plate are separated by using a mold opening at the time of forming to release the sprue.

[0003] Such a stack mold includes, for example, as shown in FIG. 7, a fixed mold plate a and an intermediate mold plate b.
A first sprue lock f and a second sprue lock g are formed by engraving a resin pool in an undercut shape on the first mold opening surface d and the second mold opening surface e of the movable mold plate c.

When the resin is filled in the stack mold, the first sprue runner h and the second sprue runner i become the first sprue lock f provided on the first mold opening surface d and the second mold opening surface e. , And is fixed by the second sprue lock g.
When the mold is opened, the first sprue lock f and the second sprue lock g are designed to have a mold holding force more than the respective necks of the first sprue j and the second sprue k. The injection-molded product was released from the mold by tearing off the neck of the sprue k.

However, in the case of such a conventional stack mold, there is a problem that the cutting position of the neck portion of the second sprue k tends to vary, and the release operation of the injection molded product tends to become unstable. .

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a stack mold capable of stably producing a large number of injection molded articles of the same shape with high productivity and a stack mold using the same. The purpose of the present invention is to provide a method for manufacturing an injection molded product.

[0007]

The invention according to claim 1 of the present application (the present invention 1) includes a fixed mold plate, a movable mold plate, and an intermediate mold plate provided therebetween. A first cavity having an inner shape corresponding to an outer shape of an injection-molded product to be molded is provided between the fixed mold plate and the intermediate mold plate at the time of mold clamping; A stack mold provided with a second cavity having an inner shape corresponding to the same outer shape as that of the injection-molded product, between the side mold plate and the fixed mold plate via a first runner. A first sprue bush having an inner peripheral portion with a first sprue communicating with the first cavity is provided, and a second sprue communicating with the second cavity through a second runner is provided on the intermediate mold plate. And the second sprue bushing A slide core is provided adjacent to the second sprue bush. The slide core is slidable with movement of the intermediate template when the mold is opened and closed. A stack mold in which the second sprue bush can be pushed out to the fixed mold plate side in conjunction with the slide of the slide core during operation.

The invention described in claim 2 of the present application (Invention 2)
Is a method for manufacturing an injection-molded article using the stack mold according to the first aspect of the present invention, wherein the molten resin is injected into the first cavity of the closed mold through the first sprue and the first runner. A step of injecting molten resin into the second cavity through the second sprue and the second runner while injecting, and opening a mold between the fixed side mold plate and the intermediate mold plate to form a mold. The slide core is slid along with the movement of the intermediate mold plate at the time of opening, and the second sprue bush is pushed out toward the fixed mold plate in conjunction with the slide, whereby the solidified resin in the second sprue is removed. A step of separating the neck portion from the solidified resin in the first sprue or the first runner; further opening the mold between the fixed mold plate and the intermediate mold plate; And mold opening between the mold plate, said first
This is a method for manufacturing an injection-molded product, in which the injection-molded product is released from the cavity and the second cavity.

[0009]

According to the first aspect of the present invention, in the stack mold, a first sprue bush having an inner peripheral portion of a first sprue communicating with the first cavity via a first runner is provided on the stationary mold plate. A second sprue bush having an inner peripheral portion with a second sprue communicating with the second cavity via a second runner is provided on the intermediate mold plate.
A slide core is provided adjacent to the sprue bush. When the mold is opened and closed, the slide core is slidable along with the movement of the intermediate mold plate. When the mold is opened, the slide core is moved along with the mold opening operation of the intermediate mold plate. Since the second sprue bush can be pushed out toward the fixed mold plate side in conjunction with the slide of the slide core, the neck portion of the resin in the second sprue is removed from the resin in the first runner. It is possible to stably cut off at a predetermined position and stably produce a large number of injection molded products of the same shape with high productivity.

The method of manufacturing an injection-molded article according to the second aspect of the present invention is the method of manufacturing the injection-molded article, wherein the first sprue and the first
A step of injecting the molten resin into the first cavity through the runner, and further injecting the molten resin into the second cavity through the second sprue and the second runner; The mold is opened between the mold plate, and the slide core is slid along with the movement of the intermediate mold plate at the time of mold opening, and the second sprue bush is pushed out to the fixed mold plate side in conjunction with the slide. Thereby, the step of separating the neck portion of the solidified resin in the second sprue from the solidified resin in the first sprue or the first runner, and further forming a mold between the fixed mold plate and the intermediate mold plate. By opening the mold between the intermediate mold plate and the movable mold plate and releasing the injection molded product from the first cavity and the second cavity, the second sprue is opened. When the shell is extruded toward the fixed-side mold plate side, the base end surface presses the surface of the solidified resin formed in the first runner, and the solidified resin formed in the second runner is pressed in the second runner. , The solidified resin formed in the second sprue can be released from the second sprue, and its neck can be stably and reliably cut at a predetermined position. ,
It is also possible to prevent the injection molded product on the first runner side from falling during opening of the mold, and it is possible to stably produce a large quantity of the same injection molded product with high productivity.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are explanatory views of an example of a stack mold according to the present invention. FIG. 1 is a cross-sectional view showing a clamped state, FIG. 2 is a cross-sectional view showing a state in which the mold is being opened, and FIG. It is sectional drawing which shows a mold opening state.

As shown in FIG. 1, this stack mold is
The apparatus includes a fixed template 1, a movable template 3, and an intermediate template 2 provided therebetween. This stack mold is provided with a first cavity C1 having an inner shape corresponding to the outer shape of an injection molded product to be molded between the fixed mold plate 1 and the intermediate mold plate 2 at the time of mold clamping, A second cavity C2 having an inner shape corresponding to the outer shape of the injection molded product is provided between the intermediate mold plate 2 and the movable mold plate 3.

The fixed mold plate 1 is provided with a through hole 12 into which the first sprue bush 11 is fitted.
The first sprue bush 11 is fitted therein. First
The sprue bush 11 has a first sprue 111
Is provided. A first runner R1 communicating from the first sprue 111 to the first cavity C1 is provided between the fixed mold plate 1 and the intermediate mold plate 2. Fixed side template 1
Is provided with a protruding plate 13 and a protruding pin 14.

The intermediate mold plate 2 is provided with a hole 22 in which the second sprue bush 21 is mounted from the fixed mold plate 1 side to the movable mold plate 3 side. The two-sprue bush 21 has its base end directed toward the fixed mold plate 1 and its distal end directed toward the movable mold plate 3,
It is mounted so as to be able to move in and out by means described later. The second sprue bush 21 is provided with a second sprue 211 on an inner peripheral portion.

The intermediate template 2 has a movable side template 3
A second sprue 211 extending toward the side extends. A second runner R2 communicating from the second sprue 211 to the second cavity C2 is provided between the intermediate mold plate 2 and the movable mold plate 3. The movable mold plate 3 is provided with a protruding plate 31 and a protruding pin 32. The movable mold plate 3 is provided with an undercut-shaped resin reservoir 33 on the runner surface. However, the resin reservoir 33 is not essential.

At the tip of the second sprue bush 21,
A stopper flange 2 protruding outwardly along the circumferential direction
12 are provided. On the base end side of the second sprue bush 21, a leg 213 having an inclined surface 213a whose diameter gradually increases toward the fixed mold plate 1 side is provided. The intermediate portion of the second sprue bush 21 is formed in a cylindrical shape having the same outer diameter.

A slide core slide groove 23 is provided in a portion of the intermediate mold plate 2 adjacent to the base end of the second sprue bush 21, and a slide core 24 is mounted in the slide core slide groove 23. Have been. In the slide core 24,
Inclined surface 221 of leg 212 of second sprue bush 21
An inclined surface 241 corresponding to a is provided. The slide core 24 is provided with an angular pin sliding hole 242 through which the distal end of the angular pin 4 whose base end is fixed to the fixed side template 1 is inserted.

As shown in FIG. 2, when the mold is opened and closed, the angular pin sliding hole 242 slides on the angular pin 4 with the movement of the intermediate mold plate 2. This allows
The slide core 24 moves toward the second sprue bush 21 while sliding in the slide core sliding groove 23. As a result, the inclined surface 241 of the slide core 24 and the inclined surface 213a of the leg 213 of the second sprue bush 21 slide with each other, so that when the mold is opened, the slide core slides by the mold opening operation of the intermediate mold plate 2. The second sprue bush 21 is pushed out to the fixed side template 1 side in conjunction with
The second sprue bush 21 is pushed back into the hole 22 in conjunction with the slide of the slide core by the mold clamping operation. The extrusion length of the second sprue bush 21 is preferably about 1 to 3 mm.

The portion of the hole 22 in which the tip end side of the second sprue bush 21 is mounted has an inner diameter corresponding to the outer diameter of the stopper flange 212 of the second sprue bush 21.
A space 211a having a length obtained by adding an extension stroke to the wall thickness is formed. The stopper flange 212 is hooked, and the second sprue bush 21 is pushed out to the fixed mold plate 1 side more than necessary. It has a stopper mechanism that prevents

As shown in FIG. 3, the gap between the fixed mold 1 and the intermediate mold 2 is further increased, and the gap between the intermediate mold 2 and the movable mold 3 is greatly increased. Is available.

Hereinafter, an example of a method for manufacturing an injection-molded article of the present invention using the stack mold described with reference to FIGS. 1 to 3 will be described with reference to FIGS. First, in the first step, as shown in FIG. 4, the molten resin is injected into the first cavity C1 through the first sprue 111 and the first runner R1 of the clamped stack mold, and The second through the sprue 211 and the second runner R2
A resin is injected into the cavity C2. At this time, the molten resin is also injected into the resin reservoir 33.

In the second step, the mold is opened between the fixed mold 1 and the intermediate mold 2 as shown in FIG. When opening and closing the mold,
As the intermediate template 2 moves, the angular pin sliding hole 242 slides with respect to the angular pin 4. Thereby, the slide core 24 is connected to the second sprue bush 2.
Move to one side. Slope 241 of slide core 24 and slope 213 of leg 213 of second sprue bush 21
a and the second sprue bush 21 is pushed out toward the fixed mold plate 1.

When the second sprue bush 21 is pushed out to the fixed mold plate 1 side, its base end surface is the first runner R
2. Pressing the surface of the solidified resin formed inside,
Since the solidified resin formed in the second runner R2 is fixed in the second runner R2, the second sprue 21
The solidified resin formed in 1 can be released from the second sprue 211, and its neck can be stably and reliably cut at a predetermined position. If the solidified resin is present in the resin reservoir 33 of the movable mold plate 3, the solidified resin serves as an anchor for the resin in the second sprue. Is more preferable because the cleavage of the compound can be further stabilized.

In the final step, as shown in FIG. 6, the mold between the fixed mold 1 and the intermediate mold 2 is further opened,
After the mold between the intermediate mold plate 2 and the movable mold plate 3 is greatly opened, the projecting plates 13 and 31 and the projecting pins 14 and 32 are protruded so that the injection molded product in the first cavity C1 and the first runner R1 and the first sprue 111 are protruded, and the injection molded product in the second cavity C2 and the second runner R2 and the second sprue 211 are released so as to protrude to obtain a plurality of injection molded products having the same shape.

[0025]

The method for manufacturing a stack mold and an injection-molded article according to the present invention is configured as described above, so that a large number of injection-molded articles of the same shape can be stably manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a closed state of an example of a stack mold according to the present invention.

FIG. 2 is a sectional view showing a state in which the stack mold shown in FIG. 1 is being opened.

FIG. 3 is a cross-sectional view showing a state in which the stack mold shown in FIG. 1 is opened.

FIG. 4 is a cross-sectional view illustrating a first step of an example of the method for producing an injection-molded article of the present invention.

FIG. 5 is a cross-sectional view illustrating an intermediate step of an example of the method for manufacturing an injection-molded product of the present invention.

FIG. 6 is a cross-sectional view illustrating a final step of an example of the method for manufacturing an injection-molded product of the present invention.

FIG. 7 is a sectional view showing an example of a conventional stack mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed side mold plate 2 Intermediate mold plate 3 Movable side mold plate 4 Angular pin 11 1st sprue bush 21 2nd sprue bush 24 Slide core 111 1st sprue 211 2nd sprue 213a, 241 Slope C1 First cavity C2 2 cavities R1 First runner R2 Second runner

Claims (2)

[Claims] 1. A fixed mold plate, a movable mold plate, and an intermediate mold plate provided between the fixed mold plate and the movable mold plate.
A first cavity having an inner shape corresponding to the outer shape of the injection molded product to be molded is provided between the fixed mold plate and the intermediate mold plate, and a first cavity is provided between the intermediate mold plate and the movable mold plate. A stack mold provided with a second cavity having an inner shape corresponding to the same outer shape as the injection-molded product, wherein the fixed side mold plate is provided with a first runner via a first runner.
A first sprue bush having an inner peripheral portion having a first sprue communicating with the cavity is provided.
A second sprue bush having an inner periphery with a second sprue communicating with the second cavity via a runner is provided, and a slide core is provided adjacent to the second sprue bush. The slide core is slidable with the movement of the intermediate template,
A stack mold, wherein the second sprue bush can be pushed out to the fixed mold plate side in conjunction with the slide of the slide core accompanying the mold opening operation of the intermediate mold plate when the mold is opened. . 2. A method for manufacturing an injection-molded product using the stack mold according to claim 1, wherein the first cavity of the clamped stack mold passes through the first sprue and the first runner. Injecting the molten resin into the mold, further injecting the molten resin into the second cavity through the second sprue and the second runner, and forming a mold between the fixed mold plate and the intermediate mold plate. The second sprue is opened by sliding the slide core in accordance with the movement of the intermediate mold plate when the mold is opened, and pushing out the second sprue bush toward the fixed mold plate in conjunction with the slide. Separating the neck portion of the solidified resin inside from the solidified resin inside the first sprue or the first runner;
The mold is further opened between the fixed mold plate and the intermediate mold plate, and the mold is opened between the intermediate mold plate and the movable mold plate, from within the first cavity and the second cavity. A method for producing an injection-molded article, comprising releasing an injection-molded article.