JPH05124064A - Mold for injection molding - Google Patents

Abstract

PURPOSE:To eliminate trouble, in which resin releasing properties in an injector are deteriorated and the general-purpose properties of the injector are narrowed. CONSTITUTION:An opening-closing device 13 opening and closing a runner 6 is mounted, and leakage from a runner 6 section of a molten resin injected into a cavity 8 and a gas is prevented by the opening-closing device 13.

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 used for producing resin products.

[0002]

2. Description of the Related Art Generally, when a resin product is manufactured by injection molding, a unit in which a nozzle 2 of an injection device 1 is joined to a sprue 4 of a mold 3 for injection molding is used as shown in FIG. The resin that is heated and melted in the cylinder 5 of No. 1 is spouted from the nozzle 2 at high pressure by the sprue 4 of the mold 3 for injection molding.
The molten resin is thereby injected into the cavity 8 via the runner 6 and the gate 7. Then, after this, the molten resin is cooled while the pressure inside the cavity 8 is kept constant, and after the resin inside the cavity 8 is solidified, the injection molding die 3 is opened and the product is taken out. The injection device 1 shown in the figure has an opening / closing valve 9 incorporated in the nozzle 2, and by closing the opening / closing valve 9 at the time of holding pressure after injection, the resin or gas (in the cavity 8) in the mold 3 is closed. The so-called hollow molding method in which a high-pressure gas is injected into the resin after injecting the molten resin is prevented from leaking from the injection device 1 portion.

Incidentally, this similar structure is disclosed in, for example, Japanese Patent Laid-Open No. 3-3.
No. 6010 publication and the like.

[0004]

However, when the opening / closing valve 9 is provided in the portion of the injection device 1 facing the resin passage as shown in FIG. 5, the resin easily adheres to and stays in the opening / closing valve 9 portion, and the injection resin However, there is a problem in that the resin is not easily removed from the inside of the injection device 1 when replacing Further, when the opening / closing valve 9 is installed in the injection device 1, the injection device 1 cannot be applied as it is to injection molding that does not require the opening / closing valve 9, so that the versatility of the injection device 1 is complicated and expensive. This will result in narrowing and increase in capital investment.

Therefore, the present invention is for injection molding which can improve the economical efficiency of factory equipment by improving so as not to deteriorate the resin removal property inside the injection device and to narrow the versatility of the injection device. It is intended to provide a mold.

[0006]

Means for Solving the Problems As a means for solving the above problems, the present invention relates to an injection molding die for introducing a heated and melted high-pressure resin into a cavity through a resin injection passage. An opening / closing device for opening / closing the injection passage was provided.

[0007]

When performing injection molding, first, the high-pressure resin heated and melted is injected into the cavity with the opening / closing device opening the resin injection passage, and then the opening / closing device closes the resin injection passage. Prevents resin and gas from leaking from the cavity.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described with reference to FIGS. Incidentally, the same parts as those of the conventional one shown in FIG.

In FIGS. 1 and 2, 10 is a fixed die supported by a fixed plate of a mold clamping device (not shown), and 11 is a movable die supported by a movable plate of the mold clamping device. The movable mold 11 and the movable mold 11 constitute an injection molding mold 12 according to the present invention. Between the fixed mold 10 and the movable mold 11 that have been clamped, a cavity 8 for molding the outer shape of the molded product is formed.
The runner 6 for introducing the molten resin and the gate 7 are formed in the cavity 8, and the sprue 4 formed in the fixed mold 10 is connected to the end of the runner 6. The resin injection passage in the present invention is composed of the sprue 4, the runner 6, and the gate 7.

Numeral 13 is an opening / closing device fixedly installed on the movable die 11. The opening / closing device 13 is the runner 6 described above.
A shield plate 14 that can close the middle of the space is formed, and a drive cylinder 15 that moves the shield plate 14 back and forth in a direction perpendicular to the runner 6. One through hole 16 is formed in the shielding plate 14, and the runner 6 communicates through the through hole 16 only when the shielding plate 14 is in the retracted state shown by the solid line in the figure.

In the drawings, reference numeral 17 is a guide groove formed in the fixed mold 10 and the movable mold 11 so that the shield plate 14 can be moved back and forth, and 18 is an ejector plate for supporting a push pin (not shown). 2 is a nozzle of the injection device 1 joined to the sprue 4.

In the above construction, when injection molding is performed, first, the fixed die 10 and the movable die 11 are in a state where the shielding plate 14 of the opening / closing device 13 is retracted (state shown by a solid line in the figure).
After that, the high-pressure molten resin is injected from the nozzle 2 of the injection device 1 into the sprue 4, and this molten resin is injected into the cavity 8 via the runner 6 and the gate 7. After completely injecting the molten resin into the cavity 8 in this way, the shield plate 14 of the opening / closing device 13 is moved forward to close the runner 6 (indicated by the chain double-dashed line in the figure) to keep the resin pressure in the cavity 8 constant. The molten resin is cooled in this state. At this time, when the runner 6 is closed by the shielding plate 14, the reverse flow of the molten resin in the cavity 8 (leakage to the injection device 1 side) is reliably prevented. After that, when the resin in the cavity 8 is solidified, the fixed mold 10 and the movable mold 11 are opened to take out the molded product, and the molding is completed.

Further, when this injection molding die 12 is applied when performing the so-called hollow molding method, the molten resin is injected into the cavity 8 and the runner 6 is closed by the opening / closing device 13. Even if the high-pressure gas is injected into the runner, there is no fear that the high-pressure gas will leak from the runner 6 portion to the outside.

As described above, when the injection molding die 12 according to the present invention is used, the molten resin and the high-pressure gas are runners 6.
Since it is possible to reliably prevent the leak through to the outside through the opening / closing device 13, there is no need to provide a valve or the like for preventing leakage on the injection device 1 side. This makes it difficult for the resin to adhere and stay inside the injection device 1, and improves the resin removal property when changing the injection resin.
Since the same injection device 1 can be used for injection molding that does not require resin leakage countermeasures, the versatility of the injection device 1 is enhanced.

The embodiment of the present invention is not limited to the one shown in FIGS. 1 and 2, but a pair of drive cylinders 15 on both sides of the runner 6 as shown in FIGS. 3 and 4, for example.
a and 15b are arranged so as to face each other, and the shield plates 14a and 14b supported by the drive cylinders 15a and 15b are moved forward and abutted at the center of the runner 6, thereby closing the runner 6. May be.

[0016]

As described above, according to the present invention, the opening / closing device for opening / closing the resin injection passage is provided, and this opening / closing device reliably prevents the molten resin or gas injected into the cavity from leaking from the resin injection passage. Since it is possible to do so, it is no longer necessary to provide a valve or the like to prevent leakage of molten resin or gas in the injection device, which deteriorates the resin removal property inside the injection device or narrows the versatility of the injection device. Will not happen. As a result, the injection resin can be replaced easily and quickly, and the complicated and expensive injection equipment can be directly applied to various injection moldings, improving the economic efficiency of factory equipment. Can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view corresponding to a portion AA in FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the same embodiment.

FIG. 3 is a plan view showing another embodiment.

FIG. 4 is a side view taken along the arrow B of FIG.

FIG. 5 is a sectional view showing a conventional technique.

[Explanation of symbols]

4 ... Sprue (resin injection passage), 6 ... Runner (resin injection passage), 7 ... Gate (resin injection passage), 8 ... Cavity, 12 ... Injection mold, 13 ... Opening / closing device.

Claims (1)

[Claims] 1. An injection molding die for introducing a heated and melted high-pressure resin into a cavity through a resin injection passage, wherein an opening and closing device for opening and closing the resin injection passage is provided. Mold.