JPS6350088Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding mold that effectively discharges gases in the mold cavity and gases generated from injected materials such as plastics and metals during molding.

During plastic molding, die casting, etc., the gas in the mold cavity and the gas generated from the molding material create cavities in the molded product and cause discoloration in plastic molding.

Conventionally, in order to exhaust such gases from the mold cavity, air vents have been usually provided on the mold mating surfaces and around the ejector pins, but in this case, molten material may enter the air vents and cause damage to the molded product. This often results in burrs, so it is necessary to post-process the molded product, clean the mold, and sometimes repair it.

Compared to conventional molds, this invention can effectively exhaust gas inside the cavity and gas generated from materials such as plastic and metal during molding.
Moreover, the purpose is to provide a molding die that does not have a negative effect on the mold or the molded product.The gist of the mold is that a recess is formed in the mold cavity, and a core pin is provided so as to protrude into the recess during molding. In the molding mold, a hole communicating from the mold cavity to the outside of the mold is provided around the core pin at least in the vicinity of the mold cavity, and a hollow part in the center of the plug is provided at the mold cavity opening of the hole. This is a molding die into which a plug made of sintered alloy penetrated by a core pin is fitted.

Next, the present invention will be explained with reference to the drawings in the case of plastic molding. FIG. 1 shows an example of the mold for plastic molding of the present invention, FIG. 2 is an enlarged view of the main part of FIG. 1, and FIG. 3 is a perspective view of a plug used in the present invention. FIG. 4 is an enlarged view of the main parts of an example of a conventional mold. In FIG. 1, the injected plastic material passes through a runner 1, a gate 2, and is filled into a mold cavity 3. At this time, the gases in the mold cavity and the gases generated from the molten plastic move into the narrow space of the mold cavity due to the injected material. In particular, in the case of a mold in which the molded product has a convex portion and a concave portion is formed in the convex portion of the molded product using a core pin as shown in Figures 1, 2, or 4, gas is generated around the core pins 5, 5', 4, 4'. They move and stay.

In the conventional mold shown in FIG. 4, the gas remaining in the portion 4' escapes to the outside of the mold from the interface between the pin 5' and the mold.
Solidification occurs faster, and residual gas causes defects in the molded product. Therefore, in the mold of this invention, as shown in Fig. 2, a hole 6 is provided from the mold cavity 3 to the outside of the mold, and this hole 6 is provided so as to surround the core pin 5 near the mold cavity, and a donut-shaped plug 7 made of sintered alloy is fitted into the mold cavity opening of the hole 6, and the pin 5 penetrates and fits into the central hollow part of this plug 7. With this structure, gas remaining in part 4 passes through the plug 7 and through the hole 6 to be quickly discharged to the outside of the mold. Fig. 3 shows the donut-shaped plug 7.
This doughnut-shaped plug is made of sintered alloy, so gas generated in the mold cavity can pass through it, but the molten plastic material does not penetrate into the plug at all. Therefore, the molded product obtained does not have defects as in the case of the conventional mold, and post-processing of the molded product is not required.
There is absolutely no need to disassemble the mold and clean it, as is the case when exhausting gas from the mold mating surfaces.

The donut-shaped plug made of a sintered alloy used in the present invention may be made of a normal sintered alloy, but it is preferable to use one having a large number of linear micropores in the axial direction because it is extremely easy for gas to pass through. Particularly preferred.

In addition, in the mold of the present invention, gas can be discharged more quickly by reducing the pressure from the outside.

As described above, since the molding mold of the present invention quickly and effectively discharges the gas in the mold cavity, there is no risk of causing defects in the molded product, and furthermore, it does not have any negative effect on the mold. It's something that doesn't exist.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an example of the molding die of the present invention, Fig. 2 is an enlarged view of its main parts, and Fig. 3 is a donut-shaped plug made of a sintered alloy used in the present invention. FIG. FIG. 4 is an enlarged view of a main part of a cross section of a conventional mold.

Claims (1)

[Scope of utility model registration request] In a molding die in which a recess is formed in the mold cavity and a core pin is provided so as to protrude into the recess during molding, the hole leading from the mold cavity to the outside of the mold is at least near the mold cavity. A molding die, in which a plug made of a sintered alloy is fitted into a mold cavity opening of the hole, the hollow part of which is penetrated by the core pin.