JPH0583366B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a molding method for obtaining a product by injecting material, and more specifically, it relates to an improvement in a molding method to obtain a product by injecting material, and more specifically, to improve a molding method in which the material injected into the mold cavity flows evenly. This invention relates to improvements in molding methods that prevent air scratches and flow defects.

[Conventional technology]

Conventionally, in material injection molding using materials such as synthetic rubber and synthetic resin, a core metal etc. is inserted into the molding mold if necessary, and the material is injected into the cavity using the material injection pot method or injection method. In many cases, a molding method was used in which the product was obtained by filling the material and waiting for it to harden.

[Problem that the invention seeks to solve]

However, when the cavity of the mold used in the above or the core metal is a molded object with a complicated shape, the opposing cavities constituting the cavity space of the mold have a surface area up to the parting surface, which is the dividing surface of the mold. Since the filling amount and amount of material are different from each other, when the injected material flows at the same speed along each cavity surface, it joins at a point away from the parting surface where air is released, and air is released to that point. This caused problems such as jamming or flow defects, which greatly increased the defective rate.

As a method to overcome this drawback, methods such as reducing the pressure inside the cavity to make it a semi-vacuum and injecting material into it to prevent air entrapment have been implemented.

However, this method has the major drawback that it requires a large investment in depressurization equipment, molds, and even molding machines, and its maintenance cannot be done at a low cost.The purpose of this method is to provide large quantities of low-priced products. cannot be used.

The present invention eliminates many of these drawbacks and provides an excellent molding method that has a simple and inexpensive configuration, freely controls the flow resistance of the injected material, and greatly reduces molding defects such as air trapping and flow defects. It is something to do.

A detailed description will be given below with reference to the drawings.

[Means for solving problems]

In the present invention, as shown in Fig. 1, a material C such as synthetic rubber or synthetic resin is injected into the cavity B of a mold A consisting of multiple parts (an upper mold and a lower mold in the figure) and heated. Or a molding method using a material injection mold A to obtain a product in a desired shape by cooling, as shown in FIG. The mold A1 having a cavity portion with a small surface area divided by
Or by applying appropriate resistance to the injection speed of the material injected from the vicinity, the material C flowing on the cavity surface B1 with a small surface area and the material C flowing on the cavity surface with a large surface area are merged near the parting surface 2 of the mold A. This feature eliminates air pockets within the mold A.

Further, as shown in FIG. 3, when the core metal 1 etc. is installed in the cavity B, the entire core surface 1a of the cavity side which is divided into upper and lower halves by the core metal 1 and has a smaller amount of material filled or A large number of depressions and depressions D are provided on one surface using the same method as described above, and each of the depressions and depressions D provides appropriate resistance to the inflow speed of material C, so that material C flows through parts with a large amount of filling and material C flows through parts with a small amount. This configuration makes it possible to eliminate air pockets within the mold A by merging them near the two parting surfaces of the mold A.

[Effect]

With this configuration, many excellent effects such as the following were obtained.

That is, as shown in Fig. 1, there is a difference in the injection distance to the parting surface 2 from which air escapes between the upper and lower sides of the cavity B in the mold A, and when the core metal 1 is installed, the injection distance between the upper and lower sides of the cavity B is different. There is also a difference in the amount of material filling on the lower side, and as it is, material C
When injected, it passes through the parting surface 2 in the middle and intersects at a point 3 where the distance and amount of the partner are equal. In order to eliminate air trapping under such circumstances, it is necessary to complete the filling of parts of the parting surface 2 with unequal distances and amounts, and to bleed air from the parting surface 2.

Therefore, as shown in FIGS. 2 and 3, the present invention provides a cavity surface B1 where material C flows faster than the other side.
Alternatively, the core metal surface 1a is surface-treated to have an uneven shape, and the flow rate of the material is suppressed by the resistance of the unevenness D, and filling is completed on the parting surface 2 portion, thereby completely removing the air and gas contained therein. In other words,
As shown in Fig. 4, the material C injected from the injection port 4 tries to flow at an equal flow rate as shown in Fig. A, but as shown in Fig. Since the short cavity part has unevenness D formed on the wall portions B1 and 1a, the flowing material C is forced to rapidly decelerate due to the uneven resistance, and the material C flowing through the other cavity part
later than that. This delay continues until the filling of material C is completed, and as shown in Figure C, the material meets near the parting surface 2 in cavity B.
If this happens, the air 5 remaining in the cavity B
are all pushed out to the outside by the material C filling the parting surface 2, thereby realizing material filling completely free of air, gas, etc.

After this, if material C is heated or cured, a perfect molded product can be obtained.

At this time, if a slight delay is sufficient to control the flow of the material, the number of irregularities D should be reduced or shallow; on the other hand, if the cavity B requires a large delay time, the number of irregularities D should be increased or the number of irregularities D should be increased.
By making the valley deeper, the optimum speed and flow rate can be obtained for various shapes and filling amounts, and molding defects in complex molds such as A can be greatly reduced.

〔Effect of the invention〕

As explained above, the present invention is a molding method using an ideal material injection mold, which has a simple structure, freely controls the flow rate and amount of the injected material, and greatly reduces molding defects. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional mold. Second
The figure is a cross-sectional view of a mold that has been subjected to the unevenness treatment of the present invention. FIG. 3 is a sectional view of a metal core subjected to the unevenness treatment of the present invention. FIG. 4 is a sectional view showing the progress of implementing the present invention. A...Mold, B...Cavity, C...Material,
D...Irregularities, 1...Core metal, 2...Parting surface.

Claims (1)

[Claims] 1. A material injection mold that injects and fills a material such as synthetic rubber or synthetic resin into the cavity of a mold consisting of a plurality of parts, and heats or cools the material to obtain a product with a desired shape. In the molding method, a large number of unevenness is provided on the entire or partial surface of the cavity surface of the mold, which has a cavity portion with a small surface area divided by a dividing surface of the mold, among the opposing molds constituting the cavity. to provide an appropriate resistance to the material injection speed injected from the parting surface or its vicinity, and to cause the material flowing through the cavity surface with a small surface area and the material flowing through the cavity surface with a large surface area to merge near the parting surface of the mold. A molding method using a material injection mold, which is characterized by eliminating air pockets in the mold. 2. After inserting a core metal into the cavity of a mold consisting of multiple parts, a material such as synthetic rubber or synthetic resin is injected and filled from the thickness direction of the core metal, and this is heated or cooled to form a desired shape. In a molding method using a material injection mold to obtain a product; of the cavity divided into upper and lower halves by the core metal, the entire surface or part of the core metal on the side of the divided cavity with a smaller amount of material filled is By providing a large number of irregularities on the part surface to provide a suitable resistance to the material injection speed that is injected from the parting surface or the vicinity thereof, the material flowing on both sides of the core metal joins near the parting surface of the mold. A molding method using material injection gold that eliminates air pockets inside.