JPH0613167B2 - Master mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a master mold used for molding a molding die for manufacturing, for example, a suspension insulator.

(Prior Art) What is usually used as a molding die for manufacturing a suspension insulator or the like is a porous resin mold in which ceramic particles are hardened with plastic. As for such a molding die, it is usual that a large number of molds having the same shape are molded by using a metal master mold whose shape is reversed.

Conventionally, in order to release the resin mold immediately after molding from the master mold, the master mold containing the mold is turned upside down and the mold is used to remove the mold from the master mold. I was taking it out. However, as shown in FIG. 3, the forming die such as the suspension insulator has a thin projection corresponding to the central pin insertion hole and the surrounding ribs, and the forming die which is the work is used when releasing the die. Since it expands when returning from the master mold, there is a problem that these thin projections are likely to be separated during the mold release from the master mold.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and provides a master mold capable of releasing a molding die without separating a thin projection portion. It was completed in order to do.

(Means for Solving the Problems) The present invention made to solve the above problems is to provide an air hole through a molding surface of a master mold body, and a pin for closing the air hole inside the air hole. In a master mold that can be freely inserted and removed, an air hole is formed so as to reach a deep recess formed in the molding surface from the back surface of the mold, and at least a part of the pin for closing the air hole, It is characterized in that it has a stepped body consisting of a relatively large diameter main body portion and a small diameter tip portion according to the shape of the air holes.

(Example) Hereinafter, the present invention will be described in more detail with reference to an example of a master mold used for manufacturing a suspended insulator.

In FIG. 1, (1) is a metal master mold body, and its molding surface (2) corresponds to the inner surface shape of a suspension insulator, for example, and has a deep recess (3) corresponding to the central pin insertion hole.
Alternatively, a deep recess (4) corresponding to the surrounding ribs is formed, and a deep recess (5) corresponding to the lightning protection element housing is formed.

(6) is preferably provided so as to reach from the back surface of the master mold body (1) to the bottoms of the recesses (3), (4) and (5) formed in the molding surface (2) thereof. It is a straight air hole. A portion of each air hole (6) near the back surface of the master mold body (1) is defined as a diameter expansion portion (7). And the tip is each concave part (3), (4), (5)
Pins (8) for closing the air holes reaching the bottom of the pin (8) are inserted into the inside of each air hole (6), and the base (9) of the pin (8) is expanded (7).
It is supported so that it can be inserted and removed by engaging with. The tips of these pins (8) are the air holes as shown in Fig. 1.
Although closing (6), attach each pin (8) to the master mold body (1).
When it is pulled out in the rear direction, the inside thereof can be used as an air blowing hole as shown in FIG.

Of these air holes (6), the air holes formed in the recess (4)
(6) has a long distance from the back surface of the master mold body (1) to the molding surface (2), and it is not preferable to make the entire diameter small, so as shown in FIG. It is what The pin (8) for closing the air hole, which is inserted into the air hole (6) of the recess (4), has a relatively large diameter according to the shape of the air hole (6) as shown in FIG. Body part (8a)
It is provided with a step consisting of a small diameter tip portion (8b).

(Operation) In the master die of the present invention thus constructed, the forming die (10) is formed by a conventional method with the pins (8) inserted into the air holes (6) as shown in FIG. Since the pin (8) closes each air hole (6) at this time, the mold is the same as the conventional master mold shown in FIG. 3 without the air hole (6).
(10) can be molded.

When the mold (10) is released from the master mold after the molding is completed, the master mold is turned over and the pins that block the air holes (6) as shown in FIG.
(8) is pulled out to the back side of the master mold body (1), and air pressure is introduced into each air hole (6). As a result, the thin projections of the mold (10), which are in the recesses (3), (4), and (5) of the master mold during release, are pushed out by air pressure and smoothly. Mold release can be performed.

Particularly in the present invention, the pin (8) for closing the air hole, which is inserted into the air hole (6) of the recess (4), has a relatively large main body portion (8a) corresponding to the shape of the air hole (6). ) And thin tip (8b)
Since it is a stepped type consisting of and, the pin (8) is an air hole.
The main body (8a) having a large diameter can be linearly moved by using the main body (8a) having a large diameter as a guide when inserting / removing to / from (6), and there is no possibility of damaging the tip portion (8b) having a small diameter. Also, the air holes in the recess (4)
Since the pin (8) can be brought into close contact with the entire inner surface of (6), there is an advantage that the resin does not easily enter the inside of the air hole (6) during molding. If the resin enters between the air hole (6) and the pin (8), pull out the pin (8) and blow air from the air hole (6). Since it is possible to increase the flow velocity at the tip portion having a small diameter, there is an advantage that cleaning can be easily performed.

Therefore, by using the master mold of the present invention, it is possible to reliably prevent separation of the protruding portion at the time of mold release, and it is possible to achieve a molding yield of 100%, which was extremely low in the past.

(Effects of the Invention) As described above, according to the present invention, at least a part of the pins inserted into the air holes reaching the deep recesses of the molding surface has a relatively large main body part and a small diameter part. By using a stepped pin consisting of the tip part, it is possible to mold the mold with an accurate shape without being affected by the air holes during molding, and after molding, remove the pin to remove air from the air holes. By blowing, the mold release can be promoted. Therefore, according to the present invention, it is possible to perform the mold release without separating the thin projection portions corresponding to the pin insertion holes of the suspension insulator and the peripheral ribs.

Further, according to the present invention, since the large-diameter main body portion can be used as a guide when the pin is inserted into and removed from the air hole, there is no risk of damaging the thin-diameter tip portion. Further, there is an advantage that the resin does not easily enter the inside of the air holes during the molding and the resin can be easily cleaned even when the resin enters.

The master mold of the present invention is not limited to the one for suspension insulators, but has a wide range of application as a master mold for a mold having thin projections.

Therefore, the present invention, as a master mold that solves the conventional problems, has a great contribution to the industrial development.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view showing a state in which a pin is pulled out, and FIG. 3 is a sectional view showing a conventional example. (1): master mold body, (2): molding surface, (3), (4), (5): recess, (6): air hole, (8): pin.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shuji Naya 383 Aikicho, Matsuto City, Ishikawa Nikko Co., Ltd. (56) References JP-A-55-161608 (JP, A)

Claims (1)

[Claims] 1. A master mold having an air hole formed through a molding surface of a master mold body, wherein a pin for closing the air hole is freely inserted into and removed from the inside of the air hole. Is formed so as to reach a deep recess formed in the molding surface, and at least a part of the pin for closing the air hole is formed to have a relatively large main body portion and a small diameter portion according to the shape of the air hole. A master mold characterized by having a step consisting of the tip part.