JPH09141670A - Mold for molding hollow rubber article and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To preclude flashes from occurring in manufacturing hollow rubber articles. SOLUTION: The movable mold and stationary mold 21 define a cavity 23, and in the cavity 23, a part of the core 24 is accommodation disposed in a manner being in contact with the inner surface of the stationary mold 21 for forming a cylindrical rubber infection space. In the mating surface of the core 24, an elastic sealing material 28 is kept so as to seal the interstice between the mating surfaces and prevent flashes from taking place. The elastic sealing material 28 is formed such that it is forced to leak out of the interstice between the mold mating surfaces of the core 24 into the sealing material forming recess by compressing and injecting a rubber material such as silicone rubber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow rubber product molding die having a core arranged in a cavity and a method for producing the same.

[0002]

2. Description of the Related Art A mold shown in FIG. 7 is known as a mold for molding a hollow rubber product, for example, a curved rubber pipe. This is a structure in which a cavity 3 is constituted by a fixed mold 1 and a movable mold 2, and a core 4 is housed and arranged in the cavity 3, and a rubber material is injected from a film gate 5 into the cavity 3 for molding. .

[0003]

However, in the molding die having the above structure, the tip of the core 4 is joined to the inner surface 1a of the cavity 3 of the fixed die 1, and the metal mating surface is used as a die mating surface. It is unavoidable that a minute gap is generated. The rubber material injected at a high pressure into the cavity 3 enters such a gap to generate a thin film-shaped burr, which takes a lot of time to remove the burr from the molded product, which causes a cost increase. There's a problem.

[0004] In order to prevent the occurrence of burrs, it is necessary to increase the mold clamping ability of the mold and to improve the machining accuracy of the mold, but these cause a large increase in cost. Even if the precision of the mold is improved, it is difficult to prevent burrs over a long period of time because the mold gradually wears.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a molding die for a hollow rubber product capable of preventing the generation of burrs, and another object is to efficiently manufacture the molding die. It is in the area of providing a manufacturing method.

[0006]

According to a first aspect of the present invention, there is provided a molding die comprising a movable die and a fixed die which form a cavity, in which a part of a core contacts an inner surface of the movable die or the fixed die. In such a case in which the cylindrical rubber injection space is formed by accommodating and arranging, the elastic seal material is attached to the mold matching surface with the core of the fixed mold or the movable mold.

In the manufacturing method according to the second aspect of the present invention, a cavity is formed by a movable die and a fixed die, and the cavity is housed and arranged so that a part of the core is in contact with the inner surface of the movable die or the fixed die. A method for producing a molding die, which comprises forming a cylindrical rubber injection space and arranging an elastic sealing material on a mating surface with a core of a fixed die or a movable die, wherein the elastic sealing material is a die. It is characterized in that it is formed by injecting the sealing material into the rubber injection space in a state where the sealing material forming concave portion is formed on the mating surface and the mold is clamped to leak the sealing material into the sealing material forming concave portion.

According to a third aspect of the present invention, there is provided a method of manufacturing a molding die according to the second aspect, wherein the movable member or the fixed mold has a mating surface with the core, and a recess for an anchor that is continuous with the recess for forming the sealing material. It has a feature in that it is formed.

[0009]

In the molding die according to the first aspect of the present invention, when a part of the core comes into contact with the movable die or the fixed die, the elastic sealing material is interposed on the die mating surface. Therefore, at the time of mold clamping, the core closely fits the elastic seal member, and it is possible to prevent the rubber material injected into the cavity from entering the gap between the mold matching surfaces and generating burrs.

In the method of manufacturing a molding die according to claim 2, when the movable die and the fixed die are clamped, and the sealing material is filled in the cavity in a state where a part of the core is in contact with the movable die or the fixed die. Due to the filling pressure, the sealing material leaks from the mating surface of the core and the movable mold or the fixed mold into the sealing material forming concave portion and fills the inside thereof. Therefore, when the mold is opened and the molded product is taken out after the sealing material is solidified, an elastic sealing material for preventing burrs is molded by the leaked portion in the sealing material forming recess.

According to the third aspect of the present invention, since the anchor recess is formed continuously with the seal material forming recess, the seal material that has entered the seal material forming recess enters the anchor recess. Therefore, the elastic seal material produced by solidifying the seal material is in a state of being fixed to the movable mold or the fixed mold by the anchor recesses, and therefore, simply,
By simply opening the mold and taking out the molded product, the elastic sealing material is fixed to a required position of the movable mold or the fixed mold, and the manufacturing and fixing of the elastic sealing material is extremely easy.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

<First Embodiment> An embodiment in which the present invention is applied to a molding die for manufacturing a rubber cap will be described below with reference to FIGS. 1 to 6. This rubber cap is used for a cable connected to a spark plug of an automobile engine, and its completed form is shown in FIG. As shown in FIG. 1, the rubber cap 10 is in the shape of a pipe bent into a substantially L-shape as a whole, and has a flange portion 11 at a tip portion to be inserted into a connection end of an ignition plug (not shown). An annular lip portion 12 for sealing is formed on the inner peripheral portion near the tip, and a tapered taper portion 13 is formed on the base end portion through which the cable is inserted.

A mold for manufacturing the rubber cap 10 is shown in FIGS. 1 to 3, and the lower fixed mold 2 is used.
1 and the movable die 22 located on the upper side are overlapped to form the cavity 2
3 is formed. A core 24 that bends in an L shape is housed in the cavity 23 with a predetermined gap from the inner peripheral surface, and a hollow cylindrical rubber injection space that bends in an L shape is formed. The cavity 23 has a sprue 25, a runner 26 and a film gate 27 shown in FIG.
The rubber is to be injected through.

The tip of the core 24 contacts the inner surface of the cavity 23 of the fixed mold 21 when the mold is clamped, so that the opening of the tapered portion 13 of the rubber cap 10 is formed. An elastic sealing material 28 is arranged on the die-matching surface of the fixed die 21 with which the core 24 abuts, as shown in FIGS. 4 and 5, and is manufactured as follows. .

First, a conical sealing material forming concave portion 29 is formed at the tip of the core 24, and, on the other hand, in the fixed die 21, an anchor concave portion is formed on the abutting surface of the core 24 and connected to the sealing material forming concave portion 29. 30 is formed. This anchor recess 30
Has a reverse taper-like depression shape that widens toward the bottom. With the recesses 29 and 30 formed as described above,
The core 24 is housed in the cavity 23 and clamped, and a rubber material made of, for example, silicon rubber or fluorine rubber is pressed and injected into the cavity 23.

By the way, this type of core 24 and fixed mold 21
In the case of adopting a mold-matching structure with, it is unavoidable that a slight gap is generated on the mold-matching surface due to restrictions on mold accuracy and mold clamping force, which has conventionally been a cause of burrs. Therefore, as described above, when the rubber material is pressed and pressed into the cavity 23, the rubber material enters the gap and gradually leaks into the seal material forming recess 29 of the core 24. Therefore, if the rubber material is kept under pressure for a longer time than the normal molding cycle, the sealing material forming recess 2 of the core 24 is formed.
The rubber material also flows into the anchor recesses 9 and the anchor recesses 30 connected to the plug 9 and fills the inside. Then, when the injected rubber material is cooled and hardened, the rubber cap 10 in the cavity 23 is made of a rubber material such as silicon rubber.
Is formed, and the elastic sealing material 28 is formed in the sealing material forming recess 29 of the core 24. Therefore, if the mold is opened and only the molded product molded in the cavity 23 is pulled out, the molded rubber cap 10 and the elastic sealing material 28
Is continuous with a thin film burr, and the elastic seal member 28 is formed with an anchor portion 28a that has entered the anchor recess 30 to prevent the elastic member 28 from coming off. Is easily broken and only the elastic seal material 28 remains fixed on the fixed mold 21 side (FIG. 4).
reference).

When the rubber cap 10 is molded with the molding die constructed as described above, the mold is clamped as shown in FIG. 1 and the cavity 23 is filled with the rubber material for the rubber cap 10. In the mold clamped state, the tip of the core 24 comes into contact with the elastic seal material 28 attached to the fixed mold 21, and due to its elasticity, a close contact state is formed and no gap is generated (see FIG. 5). Even if the cavity 23 is pressurized and filled, it is possible to reliably prevent the rubber material from entering between the core 24 and the fixed mold 21.
Therefore, it is possible to prevent the occurrence of burrs without spending a particularly large amount of money to improve the precision of the mold or the mold clamping capability of the molding device.

Moreover, particularly in the above-mentioned embodiment, the core 24
Since the sealing material forming concave portion 29 is formed in the elastic sealing material 28 by utilizing the leakage phenomenon of the filling material which is inevitably generated in the normal mold precision, the elastic sealing material 28 is separately manufactured. The manufacturing of the elastic sealing material 28 is extremely simple and rational as compared with the manufacturing method of attaching to the. Further, since the anchor recess 30 is formed in the fixed mold 21,
The rubber material for sealing leaking into the sealing material forming concave portion 29 can also be made to flow into the anchor concave portion 30 and used for fixing the elastic sealing material 28. Therefore, it is not necessary to employ a structure such as bolt tightening for fixing the molded elastic sealing material 28 to the fixed mold 21, and the manufacturing of the molding mold from this aspect is simple and more rational.

<Other Embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings. For example, the following embodiments are also included in the technical scope of the present invention. In addition to the following, various modifications may be made without departing from the scope of the invention.

(1) In the above embodiment, the core 24 is brought into contact with the fixed die 21, but the present invention is not limited to this, and the same applies to a structure in which the core 24 is brought into contact with the movable die 22. You can

(2) In the above embodiment, the cavity 23
Although the elastic sealing material 28 is molded by utilizing the leakage phenomenon of the rubber material filled in the above, the elastic sealing material 28 is not limited to this, and the separately molded elastic sealing material may be attached to the fixed mold or the movable mold.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding die showing an embodiment of the present invention.

FIG. 2 is a plan view showing a state in which the movable mold is also opened.

FIG. 3 is a sectional view of the same molding die.

FIG. 4 is a sectional view showing a molding process of the elastic sealing material.

FIG. 5 is a sectional view of the molding die, which also shows the clamped state.

FIG. 6 is a perspective view showing a similarly molded rubber cap.

FIG. 7 is a sectional view showing a conventional molding die.

[Explanation of Codes] 10 ... Rubber Cap 21 ... Fixed Type 22 ... Movable Type 23 ... Cavity 24 ... Core 27 ... Film Gate 28 ... Elastic Seal Material 28a ... Anchor Part 29 ... Seal Material Forming Recess 30 ... Anchor Recess

Claims (3)

[Claims] 1. A cylindrical rubber injection space is formed by arranging a cavity by a movable die and a fixed die, and accommodating the cavity so that a part of the core is in contact with the inner surface of the movable die or the fixed die. A mold for hollow rubber products, characterized in that an elastic seal material is attached to a mold mating surface with the core of the fixed mold or the movable mold. 2. A cavity is formed by a movable mold and a fixed mold, and a cylindrical rubber injection space is formed by arranging the cavity so that a part of the core is in contact with the inner surface of the movable mold or the fixed mold in the cavity. A method of manufacturing a molding die, in which an elastic sealing material is arranged on a mating surface of the fixed die or the movable die with the core, wherein the elastic sealing material is a sealing material on the die mating surface. A hollow rubber product characterized by being formed by injecting a sealing material into the rubber injection space in a state where a forming recess is formed and the mold is clamped to leak the sealing material into the sealing material forming recess. Mold manufacturing method. 3. The anchor recess, which is continuous with the seal member forming recess, is formed on the mold-matching surface of the movable die or the fixed die with the core.
A method for producing the hollow rubber molding die described.