JPH06312432A - Transfer molding machine for rubber - Google Patents

Abstract

PURPOSE:To reduce residual rubber to become industrial waste consuming material rubber without waste and molding a low-cost rubber product. CONSTITUTION:Six cavities 4 are provided in upper and lower molds 2, 3. A large core 5 and a small core 6 for shaping hollow parts of a pair of rubber boots are disposed in the cavities 4. Two stripes of pots 8 for containing material rubbers 7 are formed in a slender width of about half of a width of the cavity 7 in the mold 2. One sprue gate 9 is so provided in the one cavity 4 as to extend from a lateral center of the pot 8 to connecting parts of the cores 5, 6, and the pot 8 is connected to the cavity 4. A plunger 10 is vertically movably provided above the mold 2, and the rubber 7 of the pot 8 is pressurized by its pressing part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber transfer molding apparatus for molding a rubber product by injecting a material rubber contained in a pot into a cavity through a sprue gate by a plunger.

[0002]

2. Description of the Related Art A pair of hollow portions 1a, 1 as shown in FIG.
When molding the rubber boot 1 provided with b (the same figure shows the rubber boot of the load-saving valve for trucks),
Conventionally, a rubber transfer molding apparatus as shown in FIGS. 6 and 7 has been used. In this molding device,
A plurality of cavities 54 are provided by the upper mold 52 and the lower mold 53. Each cavity 54 has a large core 55 for shaping the hollow portion 1a and a small core 5 for shaping the hollow portion 1b.
6 and 6 are arranged.

A pair of pots 58 for accommodating the material rubber 57 are formed in the upper mold 52 so as to be slightly wider than the cavity 54. In addition, the upper mold 52 has a sprue gate 59 for connecting the pot 58 to the cavity 54.
Four are provided around the. Then, the material rubber 57 is heated and pressed by the pressing portion 50a of the plunger 50,
The rubber boot 1 is shaped by being injected into the cavity 54 through the sprue gate 59.

[0004]

However, according to the conventional transfer molding apparatus for rubber, since the pot 58 is formed wider than the cavity 54, the pot 5 is formed.
8 has a large bottom area. Therefore, after pressing the material rubber 57, a wide area sheet-like residual rubber 57a as shown in FIG. 8 remained at the bottom of the pot 58. This residual rubber 57
Since a is discarded although it becomes a considerable amount when accumulated, it was a great waste.

Therefore, an object of the present invention is to provide a rubber transfer molding apparatus which consumes material rubber as little as possible, can mold a rubber product at low cost, and can reduce residual rubber that becomes industrial waste. Especially.

[0006]

In order to solve the above-mentioned problems, according to the present invention, a material rubber contained in a pot is pressurized by a plunger and injected into a cavity through a sprue gate to shape a rubber product. In the transfer molding apparatus, a means is adopted in which the pot is arranged above the cavity and the pot is formed narrower than the cavity.

[0007]

According to the rubber transfer molding apparatus of the present invention, since the pot is formed narrower than the cavity, the bottom area of the pot is small, and therefore the material rubber remains at the bottom of the pot after being pressed. The sheet-shaped residual rubber also becomes narrow and has a small area. In addition, since the pressing force per unit area is high even if the total pressing force of the plunger is the same as the conventional one, the residual rubber is thinner than the conventional one. Therefore, the residual rubber is reduced, and almost the entire amount of the material rubber is injected into the cavity without waste.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 3, the rubber transfer molding apparatus of this embodiment is configured to mold six rubber boots 1 (see FIG. 4) in one shot. The upper mold 2 and the lower mold 3 are provided with six cavities 4, and each cavity 4 has a hollow portion 1 a of the rubber boot 1.
The large core 5 for shaping the hollow core 1 and the small core 6 for shaping the hollow portion 1b are arranged. The large core 5 is supported by the support plate 11 sandwiched between the upper mold 2 and the lower mold 3, and the small core 6 is supported by the lower mold 3.

On the upper mold 2, two pots 8 for accommodating the material rubber 7 are formed in an elongated shape with a width of about half the width of the cavity 4. The upper mold 2 is provided with sprue gates 9 for connecting the pots 8 to the cavities 1 in each of the cavities 4, the upper end of the sprue gate 9 being at the center of the pot 8 in the width direction, and the lower end of each of the cores 5. It is located at each of the 6 connecting portions. A plunger 10 is provided above the upper mold 2 so as to be movable up and down, and a pressing portion 10a for pressing the material rubber 7 of the pot 8 is provided on the lower surface of the plunger 10 so as to project.

At the time of molding, the upper mold 2, the lower mold 3, the large core 5,
The small core 6 is assembled as shown in FIG. 2, and the material rubber 7 is housed in the pot 8. Then, as shown in FIG. 3, the material rubber 7 is pressurized by the plunger 10 in a heated state and injected into the cavity 4 through the sprue gate 9. At this time, the sheet-shaped residual rubber 7a remains on the bottom of the pot 8.

According to the molding apparatus of this embodiment, since the pot 8 is formed with a width of about half the width of the cavity 4,
The bottom area of the pot 8 is small, and therefore, the sheet-shaped residual rubber 7a remaining at the bottom of the pot 8 after the material rubber 7 is pressed.
Also, as shown in FIG. 5, the width becomes narrow and the area becomes small. Moreover, even if the total pressure of the plunger 10 is the same as the conventional pressure, the pressure per unit area is high, so that the residual rubber 7a is thinner than the conventional one. Therefore, the residual rubber 7a is reduced in weight ratio to 1/3 to 1/4 of the conventional one, and the material rubber 7a is reduced.
Is injected into the cavity 4 without waste.

Furthermore, the flow resistance of the material rubber 7 at the bottom of the pot 8 becomes small, and a high injection pressure can be obtained without increasing the total pressure of the plunger 10. Then, the number of sprue gates 9 can be reduced to one to reduce the amount of residual material in this portion, and the material rubber 7 can be filled in every corner of the cavity 4 via the single sprue gate 9. In particular, the sprue gate 9 is located at the center of the pot 8 in the width direction and the cores 5, 6
Since it is provided between the cores 5 and 6, the material rubber 7 can be smoothly supplied to the cavity 4 around the entire circumference of the cores 5 and 6, and a pair of hollow portions 1a and 1b as shown in FIG. 4 are provided. The rubber boot 1 having a relatively complicated shape can be accurately molded with the minimum necessary material rubber 7.

The present invention is not limited to the above embodiment, but can be embodied by appropriately changing the shape and configuration of each part, as illustrated below. (1) To increase the number of sprue gates according to the shape or size of rubber products. (2) The present invention is applied to a rubber product having one or three or more hollow portions. (3) Applying the present invention to a rubber product composed of a solid body. (4) Applying the present invention to a single-piece transfer molding apparatus.

[0014]

As described in detail above, according to the transfer molding apparatus for rubber of the present invention, the material rubber can be consumed without waste, the rubber product can be molded at a low cost, and the residual rubber which becomes industrial waste can be removed. It has an excellent effect that it can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded plan view of a transfer molding apparatus for rubber according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an assembled state of the molding apparatus taken along the line AA in FIG.

3 is a cross-sectional view showing a material injection state of the molding apparatus taken along line BB in FIG.

FIG. 4 is a perspective view showing a rubber boot molded by the molding apparatus.

FIG. 5 is a perspective view showing residual rubber remaining in the molding apparatus.

FIG. 6 is a plan view of a conventional transfer molding device for rubber.

FIG. 7 is a cross-sectional view showing an assembled state of the conventional molding apparatus taken along the line CC of FIG.

FIG. 8 is a perspective view showing residual rubber remaining in the molding apparatus.

[Explanation of symbols]

1 rubber boots 1a, 1b
Hollow part 2 Upper mold 3 Lower mold 4 Cavity 5 Large core 6 Small core 7 Material rubber 7a Residual rubber 8 Pot 9 Sprue gate 10 Plunger

Claims (1)

[Claims] 1. A transfer molding apparatus for a rubber, wherein a material rubber contained in a pot is pressed by a plunger and injected into a cavity through a sprue gate to shape a rubber product, and the pot is disposed above the cavity. A transfer molding device for rubber, wherein the pot is formed narrower than the cavity.