JPH0326504A - Master mold - Google Patents

Abstract

PURPOSE:To release from a mold without performing separation of a thin protrusion, by a method wherein a pin whose tip reaches a recessed part is inserted freely extractably within an air hole reaching to the deep recessed part of a molding surface and air is blown into through an air hole by removing the pin after molding. CONSTITUTION:A master mold main body 1 possesses linear air holes 6 which are formed extending from the rear to a molding surface 2, reached up to the bottoms of recessed parts 3, 4, 5 each and penetrated through. Parts of the air holes 6 each close to the rear of the master mold main body 1 become ones 7 where diameters are expanded and pins 8 whose tips reach the bottoms of the recessed parts 3, 4, 5 each are inserted respectively within the air holes 6 each. A base part 9 of the pin 8 is supported extractably by fitting into the part 7 where the diameter is expanded. Although the tips of these pins 8 close the air holes 6 each, the insides of the holes are used as an air blowing-in hole, by pulling out the pins 8 each in the direction of the rear of the master mold main body 1. Consequently, thin protrusions of a molding tool 10, which are in a state penetrating into the recessed parts 3, 4, 5 each of the master mold 1 are extruded with air pressure at the time of mold release and the mold release is performed smooth.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a master mold used, for example, to form a precept mold for manufacturing a suspended insulator.

(Prior art) The mold normally used for manufacturing suspended insulators is a porous resin mold made by hardening Seracus particles with plastic. Usually, a large number of molds having the same shape are formed using a metal master mold whose shape is reversed.

Conventionally, in order to release such a resin mold from the master mold immediately after forming the mold, the master mold containing the mold was turned upside down, and using its own weight, the mold was released from the master mold. It was taken out of the mold. However, as shown in Figure 3, molds for suspension insulators, etc. have thin protrusions that correspond to the central pin insertion hole and the surrounding ribs, and when the mold is released, the workpiece, the mold, is damaged. The problem was that these thin protrusions tend to break off when released from the master mold because they expand as they try to return to their normal state. (iiilfi to be solved by the invention) The present invention solves these conventional problems and provides a master mold that can release the mold without separating the thin protruding parts. It has been perfected for the purpose of

(Means for Solving the Problems) The present invention, which has been made to solve the above problems, has an air hole extending from the back side of the master mold body to a deep recess formed in the molding surface thereof, It is characterized in that a bottle whose tip reaches the bottom of the recess is inserted into and removed from each air hole. (Example) The present invention will be explained in more detail below 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) has a shape corresponding to, for example, the inner surface shape of a suspension insulator.
In addition to forming a deep recess (3) corresponding to the central pin insertion hole and a deep recess (4) corresponding to the surrounding ribs,
A deep recess (5) and the like corresponding to the lightning arrester housing are formed.

(6) is preferably transparent so as to reach from the back side of the master mold body (1) to the bottom of each recess (3), (4), and (5) formed in its molding surface (2). It is a straight air hole. Master mold body (1) for each air hole (6)
The part near the back of is the enlarged diameter part (7). Then, pins (8) whose tips reach the bottoms of the recesses (3), (4), and (5) are respectively inserted into the air holes (6), and the bases (9) of the pins (8) are expanded in diameter. It is supported so that it can be inserted and removed freely by engaging with the section (7). These pins (
The tip of the pin 8) closes each air hole (6) as shown in Figure 1, but when each pin (8) is pulled out toward the back of the master mold body (1), it closes as shown in Figure 2. It has a structure that allows the inside to be used as a hole for blowing air.

(Function) The mask 1 mold of the present invention constructed as described above is manufactured by inserting an oval mold Ol in the conventional manner with the pins (8) inserted into each air hole (6) as shown in Fig. 1. At this time, the pins (8) block each air hole (6), so molding is performed in the same way as the conventional master mold shown in Fig. 3, which does not have air holes (6). When mold OII1 is released from the master mold after shaping is completed, the entire master mold is turned over and each air hole ( 6) 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, when releasing the mold, the master mold is Each recess (3), (4),
(5) The thin protruding portion of the mold 0ω that is stuck inside is pushed out by air pressure, allowing for smooth mold release. Therefore, by using the master mold of the present invention, it is possible to reliably prevent the protrusion from breaking off during demolding, and the yield rate of the mold, which was previously extremely low, can be increased to 100%. (Effects of the Invention) As explained above, the present invention has a pin whose tip reaches the deep recess of the preforming surface, which can be freely inserted into and removed from the air hole. The mold can be molded into an accurate shape without being affected by the mold, and after molding, the pins can be removed and air can be blown through the air holes to promote mold release. Therefore, according to the present invention, it is possible to release the suspended insulator from the mold without tearing off the thin protruding portions corresponding to the bottle insertion holes, surrounding ribs, etc. Furthermore, the master mold of the present invention is not limited to those for suspended insulators, but has a wide range of applications as a master mold for large-sized molds having thin protrusions. Therefore, the present invention can greatly contribute to the development of industry as a master mold that solves the conventional problems.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view with the bottle pulled out, and FIG. 3 is a sectional view showing a conventional example.

Claims (1)

[Claims] Air holes (6) reaching deep recesses (3), (4), and (5) formed in the molding surface (2) from the back side of the master mold body (1) are transparently provided, and each air hole ( Inside the pin (6), the tip reaches the bottom of the recesses (3), (4), and (5).
8) A master mold characterized by being inserted and removed freely.