JPH07186202A - Injection molding die - Google Patents

Abstract

PURPOSE:To ensure that a spool runner can be taken out surely by forming a recessed part in a surface facing the spool runner forming part of a runner stripper plate. CONSTITUTION:A recessed part 22b is provided on a surface 22a facing the runner forming part 52 of a runner stripper plate 22. The recessed part 22b is so designed that a protrusion is formed in the part 22b by a molten resin flowing into the recessed part when injection-molded. That is, a runner part 82 comes to have a protrusion 82b formed by the molten resin flowing into a gate part 82a and the recessed part 22b. Consequently, if a spool runner 8 is activated to rotate centering around a spool shaft 81 by the self-weight of the gate part 82b when a die is opened, the rotation centering around the spool part 81 of a spool runner 8 is inhibited since the protrusion 82b is insetted in the recessed part 22b. Thus the gate part 82a is constantly maintained at a fixed position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold.

[0002]

2. Description of the Related Art An injection molding die having a pin point gate does not leave a scar on the molded product, and the gate is cut and taken out from the die, which saves the trouble of cutting the gate and solidifies the gate. Since it is fast, it has the advantage that there are few internal defects near the gate of the molded product.

As this type of injection molding die, for example, a die having a three-plate structure as disclosed in Japanese Patent Publication No. 4-19009 is generally used. As shown in FIG. 3, a three-plate structure mold generally includes a fixed mold 100 and a movable mold 200, and the fixed mold 100 is composed of a fixed-side mold plate 101 and a runner stripper plate 102.

Then, as shown in FIG.
When separating the movable mold 200 and the movable mold 200 and taking out the molded product 300, the stationary mold plate 101 and the runner stripper plate 1
02 and 02 are split at the same time so that the sprue runner 400 can be removed. That is, the sprue runner 40
As shown in FIG. 4 and FIG. 5, the reference numeral 0 holds the gate portion 402 of the runner portion 401 by the holding means 500 such as a magic hand hanging from directly above the gate portion 402, and the holding means in the direction of the arrow in FIG. Move 500 to remove it from the mold. Next, the removed sprue runner 400 is sent to a conveyance means such as a belt conveyor to be collected and reused as a raw material.

[0005]

However, as shown in FIGS. 4 and 5, since the sprue portion 403 and the gate portion 402 of the runner portion 401 are in the eccentric position, the gate portion 4
With the weight of 02, the sprue runner 400 rotates around the sprue portion 403 in the direction of the arrow, and the gate portion 402 is no longer located directly below the holding means 500, so that the holding means 500 can hold the gate portion 402 well. There is a risk of disappearing.

In view of such circumstances, it is an object of the present invention to provide an injection molding die capable of reliably taking out the sprue runner.

[0007]

In order to achieve such an object, an injection molding die according to the present invention comprises a fixed-side mold plate and a runner stripper plate. The fixed-side mold plate and the runner stripper are provided. In the injection molding die in which the plate and the sprue runner forming portion are formed inside, the recess is formed on the surface of the runner stripper plate facing the sprue runner forming portion.

[0008]

According to the above structure, the molten resin is injected into the mold to fill the molten resin from the sprue runner forming portion to the cavity, and the sprue runner forming portion and the molded product are formed in the cavity. It In addition, the molten resin also enters the concave portion provided on the surface of the runner stripper plate that faces the sprue runner forming portion, and the protrusions are formed on a part of the sprue runner.

Since the projections are still fitted in the recesses of the runner stripper plate when the mold is opened, the rotation of the sprue runner about the sprue portion is suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 shows one embodiment of an injection molding die according to the present invention when viewed in cross section.
As shown in the drawing, the mold 1 includes a fixed mold 2 and a movable mold 3, and a cavity 4 is formed by closing the fixed mold 2 and the movable mold 3 together.

The fixed mold 2 is composed of a fixed mold plate 21 and a runner stripper plate 22.
The sprue runner forming portion 5 is formed by closing the runner stripper plate 22 and the runner stripper plate 22.
The sprue runner forming portion 5 includes a sprue forming portion 51 and a runner forming portion 52.

A recess 22b is provided on a surface 22a of the runner stripper plate 22 which faces the runner forming portion 52. The recessed portion 22b is formed with a protrusion, which will be described later, by the molten resin entering during the injection molding. In the figure, 11 is a protruding pin of the molded product, 2
Reference numeral 3 is a fixed die mounting plate, and 31 is a movable side die plate.

Next, a method for manufacturing an injection-molded product using the mold 1 will be described in detail in the order of steps. That is, first, as shown in FIG. 1, the fixed mold 2 and the movable mold 3 are closed, and then the molten resin is injected into the mold 1 from an injection nozzle (not shown) of the injection molding machine. The injected molten resin passes through the sprue runner forming portion 5 and is densely filled in the cavity 4. As shown in FIG. 2, a molded product 7 and a sprue runner 8 are formed by the filled molten resin.

The sprue runner 8 includes a sprue portion 81,
The runner portion 82 includes the gate portion 82a and the projection 82b formed of the molten resin that has entered the recess 22b. After the filling is completed, the fixed mold 2 and the movable mold 3 are opened. Before the fixed mold plate 21 of the fixed mold 2 and the movable mold plate 31 of the movable mold 3 are opened, first, the fixed mold is fixed. After the mold mounting plate 23 and the fixed-side mold plate 21 and the fixed-side mold plate 21 and the runner stripper plate 22 are opened in that order, as shown in FIG. Template 3
1 and are released.

When the fixed mold 2 and the movable mold 3 are released in this manner, the molded product 7 is moved to the movable side mold plate 31 as shown in FIG.
On the side, sprue runner 8 is runner stripper plate 2
It will be in a state of being attached to each of the two sides. Next, molded product 7
The sprue runner 8 is removed from the mold 1, but the molded product 7 can be taken out from the mold by a projecting pin 11 projecting in the direction of the fixed mold 2 and a taking-out means or the like (not shown) provided at the tip. You can do it. The molded product 7 taken out can be carried to a predetermined place by a carrying means such as a belt conveyor.

On the other hand, as shown in FIG. 2, the sprue runner 8 can be removed from the runner stripper plate 22 by holding the gate portion 82a by the holding means 9 and pulling it out to the movable side mold plate 31 side. There is. According to the above injection molding die 1, when the die is opened,
Even if the sprue runner 8 tries to rotate around the sprue portion 81 as a central axis due to the weight of the gate portion 82a, the protrusion 82
Since b has entered the recess 22b, rotation of the sprue runner 8 about the sprue portion 81 is suppressed. That is, the protrusion 82b serves as a detent.

Therefore, the gate portion 82a is always held at a fixed position, and if the holding position of the holding means 9 is set at the position of the gate portion 82a, the fixed die 2 and the movable die 3 are opened each time. The gate portion 82a can be reliably held by the holding means 9 and the sprue runner 8 can be taken out from the mold 1. The injection-molding die concerning the present invention is not limited to the above-mentioned example. For example, although the protrusion 22b is provided at one place in the above embodiment, it may be provided at two or more places. Further, in the above embodiment, the cavity is a single-cavity mold, but
A multi-cavity mold provided with a plurality of cavities may be used.

[0018]

As described above, in the injection molding die according to the present invention, when the die is opened, the projection provided on the sprue runner is fitted into the recess provided on the runner stripper plate. The protrusion serves as a detent to prevent the sprue runner from rotating due to the weight of the gate portion.

Therefore, if the holding position of the holding means is set at the gate portion, the sprue runner can be reliably removed by holding the gate portion by the holding means each time the mold is opened. In addition, since the posture of the sprue runner when pinched by the pinching means is always constant, the sprue runner taken out can be placed neatly at a predetermined position such as on the belt conveyor in a state always facing in a fixed direction. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of an injection molding die according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which the injection mold of FIG. 1 is opened.

FIG. 3 is a cross-sectional view showing an example of a known injection molding die.

FIG. 4 is a cross-sectional view showing a state where the injection mold of FIG. 3 is opened.

5 is a view of the runner stripper plate of the injection molding die of FIG. 3 viewed from the movable die side.

[Explanation of symbols]

 1 Injection Mold 5 Sprue Runner Molding Part 8 Sprue Runner 9 Clamping Means 51 Sprue Forming Part 52 Runner Forming Part 81 Sprue Part 82 Runner Part 22b Recess 82b Protrusion

Claims (1)

[Claims] 1. An injection molding die comprising a fixed-side mold plate and a runner stripper plate, wherein the fixed-side mold plate and the runner stripper plate are overlapped with each other to form a sprue runner forming portion. 2. An injection molding die, wherein a concave portion is formed on a surface of the sprue runner forming portion facing.