JP2000280293A - Injection molding machine for rubber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the temperature decrease and temperature dispersion of an mold and a cavity, to eliminate the restriction of the arrangement position of a gate, and to improve the use efficiency of a material. SOLUTION: In an injection molding machine for rubber which has a cold runner block 6 and controls the packing of rubber in the cavity 9 of molds 7, 8 by reciprocating a valve pin 3, the tip of the valve pin 3 is positioned at the outlet of a material channel connecting the block 6 with the cavity 9, part of the channel is composed of a cold bush part 4 of a high thermal conductivity material which is cooled by a cooling medium, a bush cover 5 formed from a low thermal conductivity material is arranged is arranged on the periphery of the bush part 4, and an air gap G is formed between the bush cover 5 and the fixed mold constituting a mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus for rubber provided with a cold runner block, wherein the filling of rubber into a cavity in a mold is controlled by reciprocating a valve pin. The tip of the valve pin is positioned at the outlet of a material flow path that communicates with the cavity in the mold, and a part of the material flow path is constituted by a cold bush portion cooled by a cooling medium, and a bush cover The present invention relates to an injection molding apparatus for rubber in which the temperature of the mold is prevented from being lowered by interposing the mold.

[0002]

2. Description of the Related Art In a conventional rubber injection molding apparatus, since a rubber molded product needs to be vulcanized and cured, a mold is heated to vulcanize the rubber. For this reason, runner gate waste is generated as waste rubber vulcanized for each molding. Since the gate portion is taken out of the mold integrally with the rubber molded product, a finishing process is required after molding.

[0003] Japanese Utility Model Publication No. Sho 59-207 discloses a method for economically molding by minimizing the runner gate waste.
As shown in FIG. 6, a cold tip C is placed between the cavity C in the mold body and the runner R in the runner block RB.
C is interposed to form a spiral cooling water groove K inside the cold chip CC to prevent vulcanization of the rubber in the runner block RB, and to use the unvulcanized rubber in the next molding. Is what you do.

In Japanese Utility Model Publication No. 4-2025, a metal bush M is disposed on a heat insulating plate D interposed between a runner plate RP and a main body as shown in FIG.
The rubber injected from N into the cavity C via the metal bush M is supplied, and the heat insulating plate D is used to prevent the rubber of the runner RN from being vulcanized.

[0005]

SUMMARY OF THE INVENTION The above conventional Japanese Utility Model No. 59
In -207, the cold tip CC is cooled by the cooling water in the spiral cooling water groove K, and the rubber in the runner R is kept in an unvulcanized state, but the rubber in the gate portion is formed by a mold. Therefore, the problem of the gate waste and the problem of the gate treatment after molding remain. Further, since the cold chip CC is in contact with the mold, the heat of the mold is taken away, and the temperature of the cavity C decreases,
There was a problem of variation.

[0006] Further, in the conventional Japanese Utility Model Publication 4-2025, since the metal bush M is installed in the heat insulating plate D, a gate can be set only at a position distant from the mold surface (PL surface). Has disadvantages. That is, in the general mold forming, the gate is arranged on the mold splitting surface (PL surface). However, in the above-described configuration, when the gate is arranged at the boundary between the heat insulating plate D and the mold 2. The insulation plate D must be part of the mold for vulcanizing the rubber, but this is not practical.

[0007] In both of the above-described conventional apparatuses, there is a problem that the material of the gate portion after molding cannot be completely used in the next molding, and that a gate finishing process is required.

Accordingly, the present inventor has proposed that a part of a material flow path connecting a cold runner block and a cavity in the mold is constituted by a cold bush portion cooled by a cooling medium. Focusing on the technical idea of the present invention that enhances heat conduction and interrupts heat conduction from the cold bush portion to the mold, as a result of further research and development, the temperature decrease and temperature of the mold and cavity In addition, the present invention achieves the object of suppressing the variation in the above and eliminating the restriction on the arrangement position of the gate, thereby achieving the object of increasing the use efficiency of the material.

[0009]

According to a first aspect of the present invention, there is provided an injection molding apparatus for rubber, wherein a rubber is injected into a cavity in a mold by reciprocating a cold runner block and a valve pin. A rubber injection molding apparatus that controls the filling of the material flow passage, wherein the tip of the valve pin is located at an outlet of a material flow passage connecting the cold runner block and the cavity in the mold, and A part constituted by a cold bush part made of a high heat conductive material cooled by a cooling medium, and a bush cover made of a material having low heat conductivity inserted between the cold bush part and the mold. It is.

[0010] In the injection molding apparatus for rubber according to the present invention (the second invention according to claim 2), in the first invention, the bush cover is arranged on an outer peripheral portion of the cold bush portion and the bush cover is arranged. An air gap is formed between the cover and the fixed mold that forms the mold.

[0011] In the rubber injection molding apparatus according to the present invention (the third invention according to claim 3), in the second invention, a heat insulating cover made of a heat-resistant resin is arranged on an outer peripheral portion of the bush cover. Things.

The rubber injection molding apparatus according to the present invention (the fourth invention according to claim 4) is characterized in that, in the second invention, high strength and heat resistance are provided between the tip of the cold bush portion and the fixed mold. The heat-insulating bush made of a resin having such a configuration is disposed.

[0013] In the rubber injection molding apparatus according to the present invention (fifth aspect of the present invention), in the fourth aspect of the present invention, the heat insulating bush is formed of a metal having low thermal conductivity outside the outer peripheral portion of the heat insulating bush. A cover is to be placed.

[0014]

In the rubber injection molding apparatus according to the first aspect of the present invention, a part of the material flow path connecting the cold runner block and the cavity in the mold is formed by a cold bush portion made of a high heat conductive material. Since the material flow path is cooled by the cooling medium, the bush cover made of a material having low thermal conductivity is interposed between the cold bush portion and the mold. This has the effect of suppressing the temperature drop and the temperature variation of the mold and the cavity.

In the rubber injection molding apparatus according to a second aspect of the present invention, in the first aspect, the bush cover is disposed on an outer peripheral portion of the cold bush portion, and the bush cover and the mold are connected to each other. Since the air gap is formed between the stationary die and the stationary die, it is possible to effectively suppress a decrease in the temperature of the mold and the cavity and a variation in the temperature.

In the rubber injection molding apparatus according to a third aspect of the present invention, since the heat insulating cover made of a heat-resistant resin is disposed on the outer periphery of the bush cover in the second aspect of the invention, This has the effect of effectively suppressing the temperature drop and the temperature variation of the cavity.

The rubber injection molding apparatus according to a fourth aspect of the present invention is the rubber injection molding apparatus according to the second aspect of the invention, which is formed of a resin having high strength and heat resistance between the tip of the cold bush portion and the fixed mold. Since the heat-insulating bush is arranged, it is possible to suppress the temperature decrease and the temperature variation of the mold and the cavity, to eliminate the restriction on the arrangement position of the gate, and to increase the use efficiency of the material.

In the rubber injection molding apparatus according to a fifth aspect of the present invention, the heat insulating cover made of a metal having low thermal conductivity is arranged outside the outer peripheral portion of the heat insulating bush in the fourth aspect. In addition, it is possible to effectively suppress the temperature drop and the temperature variation of the mold and the cavity, eliminate the restriction on the gate arrangement position, and improve the material use efficiency.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention are described below.
This will be described with reference to the drawings.

(Embodiment) The rubber injection molding apparatus of this embodiment includes a cold runner block 6 as shown in FIG. 1 and reciprocates a valve pin 3 to a cavity 9 in dies 7 and 8. A rubber injection molding apparatus for controlling the filling of rubber, wherein a material flow path connecting the cold runner block 6 and the cavity 9 in the molds 7 and 8 is formed, and a part of the material flow path is formed. Is formed by a cold bush portion 4 made of a high thermal conductive material cooled by a cooling medium, and a bush cover 5 made of a material having low thermal conductivity is arranged on an outer peripheral portion of the cold bush portion 4. An air gap G is formed between the cover 5 and the fixed mold 7 constituting the mold. The tip of the valve pin is located at the outlet of the material flow path of the cold bushing portion 4.

The cold bush portion 4 in which the material flow path is formed is cooled by a cooling medium such as water or oil. Further, the cold bush portion 4 is formed using a high heat conductive material such as an aluminum alloy, and a bush cover 5 made of a SUS alloy or the like having a low heat conductivity is formed on an outer peripheral portion thereof while actively cooling the material flow path. And the air gap G are provided.

When the length of the cold bush portion 4 becomes longer, a heat insulating cover 51 made of a heat-resistant resin such as Teflon is further provided between the SUS bush cover 5 and the air gap G.

A heat-insulating bush 1 made of a thermoplastic resin such as a PEEK (polyether-ether-ketone) material having high strength and heat resistance is arranged at a parting-out portion of the material corresponding to the outlet of the material flow path. The tip of the valve pin 3 slides on the bush 1 and the inner diameter thereof to control the filling of the rubber into the cavity of the mold. A heat-insulating cover 2 made of a titanium alloy having low thermal conductivity is provided on an outer peripheral portion of the heat-insulating bush 1. The valve pin 3 is made of metal and is configured to be able to reciprocate by a driving device such as hydraulic pressure and pneumatic pressure.

The resin used in the heat insulating bush 1 has a considerably larger volume expansion due to heat than the heat insulating cover 2 made of titanium alloy on the outer periphery thereof. Usually, since the temperature of the rubber molding die is adjusted to 160 to 200 ° C. for vulcanization of the rubber, the heat-insulating bush 1 whose upper and lower and outer peripheral directions are regulated,
The material expands so that the material flow path becomes narrow. Since the outer diameter of the valve pin that slides on the inner diameter portion also increases due to thermal expansion, the clearance between the heat insulating bush 1 and the valve pin is eliminated, and the rubber remains on the inner diameter material flowing portion wall surface of the heat insulating bush 1. The material of the gate portion can be pushed into the cavity.

Due to this effect, the material flow path is cooled with water or oil, and the temperature is adjusted to 160 to 200 ° C. by a cold runner part for controlling the vulcanization reaction and a heater, etc., so that the mold is formed between the molds. It is possible to create a sufficient material parting-off part, leaving only a gate mark on the molded product that makes it almost unnecessary to finish, and the material of the runner gate part can be used almost completely in the next molding. Efficient molding becomes possible.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) The rubber injection molding apparatus of the first embodiment is provided with a cold runner block 6 as shown in FIGS. 2 to 5, and a mold 7 is formed by reciprocating the valve pin 3. 8. An injection molding apparatus for rubber in which the filling of rubber into a cavity 9 in a cavity 8 is controlled, and an outlet portion of a material flow path connecting the cold runner block 6 and the cavity 9 in the molds 7, 8. And a part of this material flow path is constituted by a cold bush portion 4 made of a high heat conductive material cooled by a cooling medium, and a heat conductive portion is formed on an outer peripheral portion of the cold bush portion 4. A bush cover 5 made of a material having low property is arranged. Further, an air gap G is formed between the bush cover 5 and the fixed mold 7 that constitutes the mold, and has high strength and heat resistance between the tip of the cold bush portion 4 and the fixed mold 7. A heat-insulating bush 1 made of resin is arranged, and a heat-insulating cover 2 made of a metal having low thermal conductivity is arranged outside the outer periphery of the heat-insulating bush 1.

The cold runner block 6 is inserted into a spacer 61 disposed above the fixed die 7 via a heat insulating plate 10 and is disposed above the cold bush portion 4.

Above the cold bush portion 4 and the spacer 61, a cylinder portion 62 for allowing the upper end portion of the valve pin 3 to move up and down by a supplied hydraulic pump is formed, and a disc spring 63 for determining the touch pressure is provided. Attachment plate 65 as a die plate having recess 64 inserted therein
Is arranged.

A movable mold 8 movable with respect to the fixed mold 7 is disposed below the fixed mold 7, and a cavity 9 is provided between the two.
Are formed.

The operation of the rubber injection molding apparatus according to the first embodiment having the above-described structure will be described in detail with reference to FIGS.

FIG. 2 shows a state where the rubber material has been started to be injected from a molding machine (not shown) into the dies 7 and 8 of the first embodiment. At this time, the valve pin 3 is shifted upward by hydraulic pressure or pneumatic pressure, and the gate, which is the inner diameter of the heat insulating bush 1, is open.

The material injected from the molding machine is used to cool the cold runner block 6, the cold runner block 6 of which temperature is controlled to 50 to 100 ° C. by hot water or hot oil in order to improve the fluidity without vulcanizing the material. The cavity 9 is filled through the bush 4 and the inner diameter of the heat insulating bush 1.

When the filling of the material in the cavity 9 is completed, as shown in FIG. 3, the valve pin 3 is shifted downward by hydraulic or pneumatic pressure. At this time, the heat transmitted from the fixed mold 7 whose temperature is controlled to 160 to 200 ° C. by a heater (not shown) causes the heat insulating bush 1 whose upper and lower outer peripheral portions are regulated to thermally expand toward the inner diameter side, and the valve pin 3 also becomes Since the outer diameter is increased due to thermal expansion, the gate can be closed by the valve pin 3 without any material remaining on the inner material flow wall surface of the heat insulating bush 1.

In this state, the material in the cavity 9 is held while being vulcanized, and then, as shown in FIG. 4, the mold is opened at the mold splitting surface (PL surface), and as shown in FIG. Next, the molded product is released from the cavity 9. At this time, the valve pin 3 is shifted upward to prepare for the next molding.

Thereafter, the mold is closed and the state returns to the state shown in FIG. By repeating this cycle, a rubber product is injection-molded.

In the rubber injection molding apparatus according to the first embodiment having the above-described operation, the bush cover 5 is arranged on the outer periphery of the cold bush portion 4, and the bush cover 5 and the mold are formed. Since the air gap G is formed between the fixed mold 7 and the fixed mold 7, the temperature of the dies 7, 8 and the cavity 9 can be effectively suppressed from being lowered and the temperature can be prevented from being varied.

The rubber injection molding apparatus of the first embodiment is
Since the heat-insulating bush 1 made of a resin having high strength and heat resistance is disposed between the tip of the cold bush portion 4 and the fixed mold 7, the temperature of the fixed mold 7 and the temperature of the cavity 9 are reduced and the temperature is reduced. In addition, the effect of suppressing the variation in the above and eliminating the restriction on the arrangement position of the gate is achieved, and the utilization efficiency of the material is improved.

Further, in the rubber injection molding apparatus according to the first embodiment, the heat insulating cover 2 made of a metal having low thermal conductivity is arranged outside the outer peripheral portion of the heat insulating bush 1, so that the fixed mold 7 is formed. In addition, there is an effect that the temperature drop and the temperature variation of the cavity 9 are effectively suppressed.

That is, the rubber injection molding apparatus according to the first embodiment repeats the above-described cycle, thereby removing the remaining material in the cold runner block 6, the cold bush 4, and the heat insulating bush 1 in the next molding. Can be used,
In addition, very small gate traces are left on the molded product, and very efficient molding can be performed, and a great effect can be obtained by reducing industrial waste and reducing costs.

(Second Embodiment) An injection molding apparatus for rubber according to a second embodiment is provided on the outer peripheral portion of the bush cover 5 disposed on the outer peripheral portion of the cold bush portion 4 of the first embodiment. The difference is that a heat insulating cover 51 made of a heat-resistant resin is disposed as shown in FIG.

In the rubber injection molding apparatus of the second embodiment having the above structure, the heat insulating cover 51 made of a heat-resistant resin is arranged on the outer periphery of the bush cover 5, so that the fixed mold 7 and the cavity are formed. 9 has an effect of more effectively suppressing the temperature drop and the temperature variation.

The above-described embodiments and examples have been described by way of example, and the present invention is not limited thereto. The present invention will be described with reference to the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention that can be recognized by those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an injection molding apparatus for rubber according to an embodiment of the present invention and a second example.

FIG. 2 is a sectional view showing a material injection state of the rubber injection molding apparatus according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing a valve pin closing operation of the rubber injection molding apparatus of the first embodiment.

FIG. 4 is a sectional view showing a mold opening operation after vulcanization of the rubber injection molding apparatus of the first embodiment.

FIG. 5 is a cross-sectional view showing a mold release operation of the rubber injection molding apparatus of the first embodiment.

FIG. 6 is a sectional view showing a first conventional rubber injection molding apparatus.

FIG. 7 is a sectional view showing a second conventional rubber injection molding apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat insulation bush 3 Valve pin 4 Cold bush part 5 Bush cover 7 Mold (fixed type) 8 Mold (movable type) 9 Cavity G Air gap

Claims (5)

[Claims] 1. An injection molding apparatus for rubber in which a cold runner block and a rubber pin in a mold are controlled by reciprocating a valve pin, wherein the cold runner block and the cavity in the mold are controlled. The tip of the valve pin is positioned at an outlet portion of a material flow path that communicates with a part of the material flow path, and a part of the material flow path is configured by a cold bush portion made of a high heat conductive material cooled by a cooling medium. An injection molding device for rubber, characterized in that a bush cover made of a material having low heat conductivity is interposed between the mold and the mold. 2. The air conditioner according to claim 1, wherein the bush cover is arranged on an outer peripheral portion of the cold bush portion, and an air gap is formed between the bush cover and a fixed mold forming the mold. An injection molding apparatus for rubber. 3. The rubber injection molding apparatus according to claim 2, wherein a heat-insulating cover made of a heat-resistant resin is arranged on an outer peripheral portion of the bush cover. 4. The rubber injection molding according to claim 2, wherein a heat-insulating bush made of a resin having high strength and heat resistance is arranged between the tip of the cold bush portion and the fixed mold. Molding equipment. 5. The rubber injection molding apparatus according to claim 4, wherein a heat insulating cover made of a metal having low thermal conductivity is disposed outside an outer peripheral portion of the heat insulating bush.