JPH05285996A - Injection molding method for rubber products - Google Patents

Abstract

(57) [Summary] [Purpose] Easily remove injection burrs and improve mass productivity. 6 [Structure] An injection burr such as a sprue 3 and a gate 2 is attached to the injection nozzle 4 so as to be separated from the mold 5.
After opening the so that the injection nozzle 4 is separated from the mold 5,
The injection burrs such as the sprue 3 and the gate 2 are attached to the nozzle 4 and taken out, and in parallel with the taking-out of the product 7, the injection burrs such as the sprue 3 and the gate 2 are removed from the nozzle 4 at the same time. ing. The injection burrs such as the sprue 3 and the gate 2 can be easily removed because the portion attached to the nozzle 4 is in an unvulcanized state.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for injection molding rubber products. More specifically, the present invention relates to an injection molding method suitable for molding small seal parts such as oil seals and seal caps.

[0002]

2. Description of the Related Art Conventionally, when injection molding a small rubber product such as an oil seal or a seal cap, as shown in FIG. 5, the center of a movable mold 106, that is, the center of a cavity (in other words, a molded product) 101. An injection nozzle 104 is arranged at the position so that the sprue 102 and the cavity 101 are connected by a radial film gate 103. Sprue 102
A nozzle 104 is pressed against and the molten molding material (unvulcanized molten rubber) is injected. And after injection molding is completed,
The nozzle 104 is separated from the movable mold 106 and then the mold 1
The molded product 108 is taken out by opening 06 and 107. At this time, the molded product 108 has a film gate 1
03, sprue 102 and other injection burrs are attached,
This is cut or stripped using a cutting tool or device.

[0003]

However, since injection burrs remain on the product in this conventional injection molding method, it is necessary to perform deburring after taking out the product, which requires two steps. Usually, a deburring tact that is about the same as or slightly shorter than the product take-out tact is required, which reduces productivity.

Further, the need for a device for deburring leads to an increase in equipment cost. Even when the injection burr is stripped from the product, some of the gates and sprue near the product have already been vulcanized together with the product, which requires considerable force. May be attached.

Further, as shown in the drawing, the injection nozzle 1 is provided at the center of the product.
When 04 is arranged and the sprue 103 and the cavity 101 are connected by the radial product-size film gate 102, many injection burrs are generated, the yield of the material is deteriorated, and the removal from the product 108 is not easy.

[0006] It is an object of the present invention to provide an injection molding method in which injection burrs can be easily removed and mass productivity can be improved.

[0007]

In order to achieve the above object, the injection molding method for a rubber product of the present invention attaches an injection burr such as a sprue or a gate to an injection nozzle and separates it from the mold.

Further, in the injection molding method for a rubber product of the present invention, the injection nozzle is separated from the mold after the mold is opened.

[0009]

Therefore, the injection burr adheres to the nozzle and is taken out, and does not exist in the product taken out from the mold when the mold is opened. Therefore, the removal of the injection burr from the nozzle is performed simultaneously with the removal of the product. At this time, the injection burr can be easily removed because the portion attached to the nozzle is in an unvulcanized state.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows an embodiment of an injection molding apparatus for carrying out the injection molding method of the present invention. This injection molding apparatus has at least two molds 5 and 6 that can be divided, and an injection nozzle 4 that injects a molten injection molding material (unvulcanized molten rubber material) into a cavity 1 formed between them. One movable mold 5 has a sprue 3 and the sprue 3 and the cavity 1.
A pin gate 2 is formed at one location for connecting between the sprue 3 and the sprue 3 so as to directly inject the molten molding material into the cavity 1 from one location through the pin gate 2.

A rubber product is molded as follows using the molding die constructed as described above.

First, if necessary, a reinforcing metal ring is set at a predetermined position in the cavity 1 of the molds 5 and 6 in the divided state. Next, the molds 5 and 6 are closed and the nozzle 4 is pressed against the mold 5 to inject the molten molding material. Melt molding material is sprue 3
Is directly injected into the cavity 1 through the pin gate 2. Then, the inside of the cavity 1 is distributed in the circumferential direction to fill the inside of the cavity 1. As a result, the specified product 7
Is obtained (see FIG. 1A).

After the completion of injection molding, the molds 5 and 6 are opened first, and the injection burr (sprue 3 and pin gate 2) and the product 7 are separated by the mold opening force at that time (see FIG. 1B).

Next, the injection nozzle 4 is separated from the movable die 5 and the injection burr (sprue 3 and pin gate 2) is injected into the nozzle 4.
It is taken out from inside the movable mold 5 in a state of being attached (see (C) of FIG. 1).

Then, in parallel with the removal of the product 7 from the fixed lower mold 6, the injection burr from the nozzle 4 is removed at another place at the same time. Generally, it takes less time to remove the injection burr than to remove the product 7.
The deburring and the removal of the injection burr are completed almost simultaneously or the deburring is completed first.

FIG. 2 shows another embodiment. In this embodiment, the injection nozzle 4 is used more than the fixing force between the injection burrs 2 and 3 and the product 7.
This method is used when the fixing force between the injection burr 2 and the injection burr 2 is superior. That is, after the desired product 7 is injection-molded in the same manner as in the method of FIG. 1 (see FIG. 2A), the injection nozzle 4 is first separated from the movable mold 5 and the sprue 3 and the pin gate 2 are removed.
The injection burr made of is attached to the nozzle 4 and taken out (see FIG. 2B). Then, the molds 5 and 6 are opened and the product 7 is taken out from the fixed lower mold 6.

Furthermore, FIG. 3 shows another embodiment. In this embodiment, the injection nozzle 4 and the sprue 3 are arranged in the center of a molded product (product 7). This embodiment is different from FIG. 1 in that the positional relationship between the product 7 and the injection nozzle 4 and the like is different, and the product removal and injection burr removal steps are similar to those of the embodiment of FIG.

Furthermore, FIG. 4 shows another embodiment. In this embodiment, the injection nozzle 4 and the sprue 3 are arranged in the center of a molded product (product 7). This embodiment is different from FIG. 2 in that the positional relationship between the product 7 and the injection nozzle 4 and the like is different, and the product removal and injection burr removal steps are similar to those of the embodiment of FIG.

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention. For example, although the sprue 3 and the cavity 1 are connected to each other by the pin gate 2 in this embodiment, the present invention is not particularly limited to this, and the position of the sprue or the like is not particularly limited. Further, when the injection is performed at one location by the pin gate as in this embodiment, the injection burr can be reduced and the yield of the material can be improved, but the present invention is not particularly limited to this, and the molten molding material can be injected from a plurality of locations. You can

[0021]

As is apparent from the above description, in the injection molding method for a rubber product of the present invention, the injection burr such as a sprue or a gate is attached to the injection nozzle to separate it from the mold. It does not exist on the product side. Therefore, the removal of the injection burr from the nozzle can be performed simultaneously with the removal of the product. Moreover, the injection burr can be easily removed because the part attached to the nozzle is in an unvulcanized state. For example, in the case of the oil seal shown in FIG. 1, conventionally, each work time for taking out the product and removing the burr was required, but in the case of the injection molding method of the present invention, at the same time, taking out the product and removing the burr are performed at different places. Since it is done, it is possible to shorten the time.

Further, when the injection nozzle is separated from the mold after the mold is opened, the product and the injection burr are reliably separated by the force of the mold opening, so that the product and the injection burr can be easily removed even if they have a strong fixing force. be able to.

[Brief description of drawings]

FIG. 1 is an explanatory view illustrating an injection molding method for a rubber product of the present invention, in which (A) is an injection molding state, (B) is a mold opening state,
(C) shows the injection | pouring burr removal state, respectively.

2A and 2B are explanatory views for explaining another embodiment of the injection molding method for a rubber product of the present invention, where FIG. 2A is an injection molding state, FIG. 2B is a mold opening state, and FIG. Shown respectively.

FIG. 3 is an explanatory view for explaining another embodiment of the injection molding method for a rubber product of the present invention, in which (A) is an injection molding state, (B) is a mold opening state, and (C) is an injection burr removal state. Shown respectively.

4A and 4B are explanatory views illustrating another embodiment of the injection molding method for a rubber product according to the present invention, in which FIG. 4A is an injection molding state, FIG. 4B is a mold opening state, and FIG. Shown respectively.

FIG. 5 is an explanatory diagram showing a conventional injection molding method of an annular seal material.

[Explanation of symbols]

 2 Pin gate as injection burr 3 Sprue as injection burr 4 Injection nozzle 5 Movable type 6 Fixed type 7 Products

Claims (2)

[Claims] 1. A method of injection molding a rubber product, comprising:
An injection molding method for a rubber product, characterized in that an injection burr such as a sprue or a gate is attached to an injection nozzle and separated from a mold. 2. The injection molding method for a rubber product according to claim 1, wherein the injection nozzle is separated from the mold after the mold is opened.