JPS591772Y2 - Molding mold - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a mold for molding synthetic resin, etc.

Conventionally, when molding products such as synthetic resin using an injection molding machine, gas generated from the molten resin injected into the mold was forced out of the mold cavity through the gap between the split surfaces of the mold. or a part or all of the part facing the mold cavity is made of sintered metal, and there are small holes between the metal particles of the sintered metal that allow gas to pass through but not resin. A number of methods have been proposed, including one in which a

However, these conventional techniques have unresolved problems in practical use, such as resin entering the gap between the mold dividing surfaces, causing cracks in the molded product, and clogging of the sintered metal over time. Met.

The present invention was made to solve the above-mentioned drawbacks of the prior art, and its gist is that a mold cavity for forming a cylindrical molded product is constructed from an outer surface molding mold and an inner surface molding mold, and the cylindrical molded product is The part that forms the end face of the mold cavity is a dead end for the resin flowing inside the mold cavity, and the mold cavity face at the part where the resin ends is a small hole that communicates the mold cavity and the space outside the mold. One end is opened, and a gas venting pin is inserted into the small hole with its tip protruding into the mold cavity, allowing communication between the mold cavity and the space outside the mold in a state where the pin is protruded. A notch is formed from the vicinity of the tip to the rear end, and the tip retreats against the spring pressure by the resin injected into the mold cavity, closing the small hole and cutting the tip surface. The present invention resides in a mold characterized in that the mold is flush with the surface of the mold cavity.

Next, an embodiment of the molding mold of the present invention will be described in detail with reference to the drawings.

In Fig. 1, 1 is a fixed side mold mounting plate, 2 is a fixed side mold, and the fixed side mold 2 corresponds to the outer surface molding mold 3 for molding the outer surface of the left half of the cylindrical molded product. It consists of a mold 4 for molding the inner surface.

Reference numeral 5 denotes a movable side mold mounting plate, and 6 a movable side mold.The movable side mold 6 includes an outer molding mold 7 for molding the outer surface of the molded product, a corresponding inner molding mold 8, and a product ejection plate. 9 and a product ejection sleeve 10.

11 is a gate, and 12 is a mold cavity.

Therefore, one end of a small hole 14 is formed in the mold cavity surface 13 of the mold 4 for molding the inner surface at the part where the resin flowing to the left through the gate 11 reaches the end, that is, the part where the end face of the cylindrical molded product is molded. The small hole 14 is bent into an L shape along the fixed side mold mounting plate 1 from the middle, passes through the fixed side mold 2, and the other end is opened outside the mold, thus forming a mold cavity 12 and a space outside the mold. It is communicated with.

Further, as shown in FIG. 2, a gas venting pin 15 is fitted into one end opening of the small hole 14 with its tip 16 protruding into the mold cavity 12. Third
As shown in the figure, the tip portion 16 is made up of the tip portion 16 and a leg portion 17 having a smaller diameter and longer than the tip portion 16.
When this protrudes into the mold cavity 12, the mold cavity 12
The cutout part 1 is made so as not to obstruct the communication between the mold and the outside space of the mold.
B is provided.

A spring 19 is fitted around the outer periphery of the leg portion 17 of the gas venting pin 15, and the tip end 16 of the gas venting pin 15 is pressed against the spring 19 by the resin pressure of the resin 20 injected into the mold cavity 12.
It retreats inside the small hole 14 while resisting the spring pressure of the small hole 1.
4 is completely closed, and the distal end surface 21 is stopped when it becomes flush with the surface of the other mold cavity, and after the molded product is taken out, it is automatically advanced by the spring 19 and restored. being done.

In the present invention, the small holes for communicating between the mold cavity and the space outside the mold are provided only in a part of the part where the resin flowing inside the mold cavity becomes a dead end, as in the above-mentioned embodiment. It may be provided on the mold cavity surface of all parts.

In addition, when the tip of the degassing pin protrudes into the mold cavity, it maintains communication between the mold cavity and the space outside the mold, and also serves as a means to completely close the small hole when retreated by molten resin. Another method is to provide the gas venting pin itself with a tapered notch whose diameter gradually decreases from the tip to the rear end, and to provide a corresponding taper on the inner surface of the small hole.

Next, the operating state of the molding die of the present invention will be explained based on the above-mentioned embodiments.

When the stationary mold 2 and the movable mold 6 are in a closed state and before the molten resin is injected, the gas vent pin 15 is caused to protrude from the mold cavity surface 13 by the spring 19 as shown in FIG. Next, molten resin 20 is injected into the mold cavity 12 through the gate 11, and the molten resin 20 causes the tip portion 1 to be injected into the mold cavity 12.
Until 6 is pressed, the gas generated from the molten resin 20, together with the air remaining in the mold cavity 12, flows into the notch 18,
It is discharged via the small hole 14.

Therefore, the gas vent pin 15 is covered with the molten resin at the tip 16.
When pressed, it retreats inside the small hole 14 against the pressure of the spring 19, completely closing the small hole 14, and the tip surface 21 becomes flush with the surface of the mold cavity 12, as shown in FIG. It will be done.

When the molten resin 20 thus injected is cooled and solidified,
When the mold is split open, the molded product adheres to the inner molding mold 8 and is released from the mold cavity surface 13. At this time, the degassing pins 15 are automatically successively projected from the small holes 14 by the action of the springs 19. When the state as shown in FIG. 2 is restored and the molded amount is completely released from the mold by the action of the ejector plate 9, ejector sleeve 10, etc., the mold is closed again, and the same cycle is repeated thereafter.

According to the molding mold of the present invention, one end of the small hole that communicates the mold cavity with the space outside the mold is opened in the mold cavity surface at the part where the resin flowing inside the mold cavity becomes a dead end, and the small hole is opened at the opening. Until the resin injected into the mold cavity reaches the dead-end part of the mold cavity surface, gas is released from the small hole to the outside of the mold, and when it reaches the mold cavity, the resin pressure closes the small hole. , and because it has a structure in which a gas venting pin that can be automatically restored when the mold is released is inserted, a gap is provided for gas venting on the dividing surface of the mold when the mold is closed, as in the past. There is no need to do so, and since the split surfaces are in close contact, there is almost no formation of flakes on the molded product, and over time, the small holes and pins for degassing can become clogged, making it difficult to degas. There is no fear that functionality will deteriorate.

[Brief explanation of the drawing]

Fig. 1 is a partially omitted cross-sectional view showing one embodiment of the molding mold of the present invention, Fig. 2 is a perspective view showing only the left inner mold of the same mold, and Fig. 3 is the same as the above. It is a partially cutaway perspective view showing only the degassing pin taken out of the mold for molding the inner surface. 2 is a fixed side mold, 3 and 7 are molds for external molding, 4 and 8 are molds for internal molding, 6 is a movable mold, 12 is a mold cavity, and 13 is a mold cavity surface at the dead end part of the resin flowing to the left. , 14 is a small hole, 15
16 is a gas release pin, 16 is a tip, 18 is a notch, 19 is a spring, 20 is a resin, and 21 is a tip surface.

Claims (1)

[Scope of utility model registration request] A mold cavity for molding a cylindrical molded product is constituted by an outer molding mold and an inner molding mold, and a portion for molding an end face of the cylindrical molded product is a dead end portion of the resin flowing inside the mold cavity. , One end of a small hole that communicates the mold cavity and the space outside the mold is opened in the mold cavity surface where the resin ends, and a gas vent pin is inserted into the small hole with its tip inserted into the mold cavity. A notch is formed from the vicinity of the tip to the rear end so that the mold cavity can communicate with the mold cavity and the space outside the mold in the protruding state. A mold for molding, characterized in that the resin injected into the cavity retreats against spring pressure to close the small hole, and the distal end surface thereof is flush with the surface of the mold cavity.