JPH06290663A - Molding metal mold for insulator and its molding method - Google Patents

Abstract

PURPOSE:To provide an insulator molding metal mold and its molding method which can prevent a core from being damaged while being held, and can provide excellent yield. CONSTITUTION:A insulator molding metal mold forms cap 23 and sheath 24 being composed of rubber around a core 21 by upper 1 and lower molds 2 having cavity 5. End caps 7 are installed at both the ends of the core 21, and are fixed at each specified position between the upper and the lower molds 1 and 2 with the covers closed, so that the core 21 is thereby positioned. Each end cap 7 is furnished with a tapered surface 7b, and is positioned by the action of the tapered surface 7b with respect to the molds 1 and 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die and a molding method for manufacturing a non-ceramic insulator having a shade made of rubber or resin, which is used for supporting electric wires.

[0002]

2. Description of the Related Art Conventionally, a transfer molding apparatus has been used for molding a housing of a non-ceramic insulator having many shades and sheaths. In this transfer molding apparatus, a core is horizontally fixed in a cavity, a vacuum is drawn, and in this state, a flowable rubber, which is a raw material, is injected under pressure to manufacture a rubber molded product. In the case of a transfer molding machine, a vacuum of 5 m is required for ultra-high voltage power transmission due to restrictions such as the size of the molding machine and the dimensional accuracy of the mold.
It was not possible to mold the insulator housing that crossed over at once. In order to solve such a problem, a method has been proposed in which a preform having a rubber layer formed concentrically on a core is compression-molded to form a shade and a sheath. As shown in FIG. 5, the mold 50 used in the step of compression-molding this preform is composed of an upper mold 50a and a lower mold 50b, and the upper mold 50a and the lower mold 50b each have a cavity 51.
have. The shade is formed by the cavity 51. The preform 52 is the mold 5
It is inserted into 0 and is compression molded into a predetermined shape by heating. Therefore, it is not necessary to evacuate the inside of the cavity 51, and a non-ceramic insulator having a housing length of 5 m or more can be easily formed.

[0003]

However, in the above-mentioned prior art, the rubber layer 54 of the preform 52 usually includes the rubber of the shade portion and is larger than the diameter of the sheath. Therefore, when the preform 52 is set on the mold 50, the end of the core 53 is not set on the mold surface but is held in a floating state. The upper and lower molds 50 in this state
When compression molding is performed by tightening a and 50b, the position of the core 53 may be displaced, and the core 53 itself may move up and down.
It was sometimes pinched by 50b and damaged.

The present invention has been made by paying attention to the problems existing in such a conventional technique, and an object thereof is an insulator having a good yield in which a core is not damaged by being sandwiched between molds. To provide a molding die and a molding method.

[0005]

In order to achieve the above object, in the first aspect of the invention, there is provided an insulator in which a rubber cap and a sheath are formed around a core by an upper mold and a lower mold having a cavity. The gist of the present invention is that a molding die is provided with positioning means attached to both ends of the core and fixed to a predetermined position between the two dies by closing the die to position the core.

Further, the gist of the second invention is that the positioning means has an inclined surface and is positioned with respect to the mold by the action of the inclined surface. Further, the gist of the third invention is that the positioning means is an end cap provided with a concave portion forming a ring-shaped protruding portion along the outer peripheral surface of the sheath end portion.

Further, in the fourth aspect of the invention, in a method of molding an insulator in which a cap and a sheath made of rubber are molded around a core by an upper mold and a lower mold having a cavity, a rubber layer is attached around the core. The positioning means is attached to the preform of the insulator, and the core is placed and set in the lower mold with the lower mold opened from the upper mold.The upper mold and the lower mold are heated to a predetermined temperature and The gist is that the mold and the upper mold are closed and compression-molded into a predetermined shape.

[0008]

With the above structure, the positioning means is attached to the core, and the core is placed and set on the lower mold with the lower mold opened from the upper mold. The lower mold and the upper mold are closed. At this time,
Even if the position of the core is deviated, as the lower mold and the upper mold are closed, the slant surface of the positioning means and the mold slide, and the core is moved to a predetermined position.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a molding die for a non-ceramic insulator will be described below with reference to the drawings.

As shown in FIG. 1, a molding die for an insulator is composed of an upper die 1 and a lower die 2. The upper mold 1 and the lower mold 2 are formed by stacking a plurality of divided upper mold pieces 1a, 1b, 1c and lower mold pieces 2a, 2b, 2c, respectively.
The uppermost mold pieces 1a and 1b and the lower mold piece 2 adjacent to the end portions
Except for a and 2b, the upper mold piece 1c and the lower mold piece 2c in the middle part all have the same shape. A long bolt 3 is inserted into each of the upper mold pieces 1a, 1b, 1c and the lower mold pieces 2a, 2b, 2c from one end, and is screwed by a nut 4 to be fastened and fixed to be integrated. There is. By arbitrarily changing the numbers of the upper mold piece 1c and the lower mold piece 2c in the middle portion, the length of the insulator to be molded can be freely adjusted.

The cavity 5 is formed by the upper mold 1 and the lower mold 2, and has a shape of a plurality of non-ceramic insulator caps and sheaths. The receiving parts 6a, 6b are the endmost parts and the upper mold pieces 1a, 1b adjacent to them and the lower mold pieces 2a,
2b. Both of the receiving portions 6a and 6b form a short cylindrical shape. The end cap 7 constituting the positioning means is housed in the receiving portions 6a and 6b. The end caps 7 are attached to both ends of the core 21 of the non-ceramic insulator 20, and the core 2 is attached at the time of molding.
Positioning 1 is performed. Further, the insertion hole 8 for the ejector pin is formed in the lower mold piece 2a, 2b at the end, and the ejector pin after the insulator is formed is inserted into the insertion hole 8 and the end cap 7 is pushed up. 7 can be taken out from the receiving portions 6a and 6b.

As shown in FIGS. 2 and 3, the end cap 7 is formed in a cylindrical shape and has a guide portion 7a having an outer diameter larger than the other at one end. Both end surfaces of the guide portion 7a are slightly inclined, and tapered surfaces 7b are formed. The receiving portions 6a and 6b are also formed with slopes along the tapered surface 7b. The molds 1 and 2 are designed so that their slopes are guided along the tapered surface 7b. The core gripping portion 7c is provided at the center of the end cap 7. The core 21 is set in the molds 1 and 2 while being fitted in the core gripping portion 7c. A screw hole 7d is formed at the other end of the guide portion 7a of the end cap 7, and a set screw member 9 is screwed onto the screw hole 7d. The core 21 can be easily taken out from the end cap 7 by removing the set screw member 9 and pushing the core 21 fitted in the end cap 7 with a rod-shaped take-out tool. Spacer 10
Is sandwiched between the end cap 7 and the set screw member 9 and held so as to close the through hole of the core gripping portion 7c. The core 21 may expand due to its temperature during the molding of the insulator, extend in the direction of the set screw member 9 and come into contact with the spacer 10. The spacer 10 is formed of a Teflon plate to prevent the end of the core from being scratched.

The sheath end forming recess 7e is formed into the core gripping portion 7c.
Is provided on the inlet side of the sheath and forms a portion at the end of the sheath 24 in contact with the grip of the insulator. O-ring molding recessed portions 7f are provided at two locations inside the taper surface 7b of the end cap 7 near the sheath end forming recessed portion 7e and inside the core gripping portion 7c. A rubber material is supplied to the O-ring forming recess 7f to mold the O-ring. The O-ring improves the sealing property between the gripping metal and the end of the sheath 24. Further, a groove is formed on the inner peripheral surface of the sheath end portion forming recess 7e to form a rubber flow stopper 7g. The rubber flow stopper 7g is for collecting the rubber leaking from the sheath end portion forming concave portion 7e during molding of the insulator so as to prevent the rubber from leaking further toward the core end portion. Since the rubber in the portion of the flow stopper 7g is not adhered to the core 21 by an adhesive, it is possible to obtain a neatly aligned end of the sheath 24 by cutting it off after forming the insulator.

Next, a method for forming a non-ceramic insulator using the insulator forming die having the above structure will be described. As shown in FIG. 4, first, the end cap 7 is attached to the insulator preform 25 having the rubber layer 22 attached around the core 21, and the core 21 is opened with the lower mold 2 opened from the upper mold 1. Place on the lower mold 2 and set. Since the outer diameter of the preform 25 is larger than the diameter of the cavity 5 for molding the sheath 24, the end cap 7 has a receiving portion 6
It is not housed in a and 6b but is held in a floating state. The upper die 1 and the lower die 2 are heated to a predetermined temperature, and the lower die 2 and the upper die 1 are closed by a press machine (not shown).
At this time, even if the position of the core 21 of the preform 25 is slightly deviated, as the lower mold 2 and the upper mold 1 are closed, the receiving portions 6a and 6b and the guide portion 7a are brought into sliding contact with each other and the guiding action thereof is performed. Thereby, the core 21 is moved to a predetermined position around the center of the cavity 5.

As shown in FIG. 1, the preform 25 is compression molded into a predetermined shape by the molds 1 and 2. Since the volume of the rubber layer 22 of the preform 25 is larger than the volume of the cavity 5, the rubber layer 22 fills all of the cavity 5 and expels air when compression-molded by the molds 1 and 2, and the rubber layer 22 causes the sheath to move. 24 and the shade 23 are molded. Further, the end portion of the sheath 24 is molded by the sheath end portion forming recess 7e of the end cap 7. The remaining rubber protrudes from the cavity 5 and is extruded on the mold splitting surface to form burrs.
The vulcanization temperature at the time of molding is usually selected between 150 ° and 180 ° C., and a vulcanized and bonded interface having a high electrical reliability is formed between the sheath 24 and the core 21.

The molded product of the non-ceramic insulator 20 is taken out from the molds 1 and 2 by inserting the ejector pin through the insertion hole 8 for the ejector pin of the lower mold pieces 2a and 2b and pushing up the end cap 7. Further, the end cap 7 is removed from the core 21, and the burr protruding at the end is removed to complete the finished product.

As described above, in the molding die of the non-ceramic insulator of this embodiment, since the positioning end cap 7 is provided, the core 21 stays at the predetermined position even if the position of the preform 25 is slightly displaced. You can move.

Further, since the end cap 7 is provided with an O-ring forming concave portion 7f forming a ring-shaped protruding portion along the outer peripheral surface of the sheath end portion, there is no parting line in the axial direction and waterproof with the gripping metal fitting. Can be performed more reliably.

The present invention is not limited to the structure of the above-mentioned embodiment, and for example, the present embodiment is applied to the compression molding die, but it may be used for an ordinary injection molding die. Further, instead of the cylindrical guide portion of the end cap, it may be embodied by making a spherical shape or the like without departing from the spirit of the present invention.

[0020]

As described above, according to the present invention, since the positioning end cap is provided, even if the position of the core is slightly displaced, it can be moved to a predetermined position by the guiding action of the guide portion, and the core can be moved up and down. It will not be caught in the mold and damaged,
This has the effect of improving the yield.

Further, since the end cap is provided with a recess forming a ring-shaped protrusion along the outer peripheral surface of the sheath end, there is no parting line in the axial direction, and waterproofing with the gripping metal is performed more reliably. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of an insulator molding die embodying the present invention.

FIG. 2 is a sectional view of an end cap.

FIG. 3 is an enlarged cross-sectional view showing the vicinity of a sheath end forming recess of the end cap.

FIG. 4 is a side view showing a state in which a preform of the insulator is set in a molding die.

FIG. 5 is a cross-sectional view showing a conventional molding die.

[Explanation of symbols]

1 upper mold, 2 lower mold, 5 cavities, 7 end caps as positioning means, 7b tapered surface, 21 cores, 23 shades, 24 sheaths.

Claims (4)

[Claims] 1. A molding die for an insulator, wherein a cap and a sheath made of rubber are molded around a core by an upper mold and a lower mold having a cavity, the mold being attached to both ends of the core, and the mold being closed between the molds. A molding die for an insulator, comprising a positioning means fixed to a predetermined position for positioning the core. 2. The molding die for an insulator according to claim 1, wherein the positioning means has an inclined surface and is positioned with respect to the die by the action of the inclined surface. 3. The molding die for an insulator according to claim 1, wherein the positioning means is an end cap provided with a concave portion that forms a ring-shaped protrusion along the outer peripheral surface of the sheath end portion. 4. A method for forming an insulator, comprising forming a shade and a sheath made of rubber around a core by means of an upper die and a lower die having a cavity, wherein a preform of the insulator having a rubber layer attached to the periphery of the core. The core is placed and set on the lower mold with the positioning means attached and the lower mold opened from the upper mold. The upper mold and the lower mold are heated to a predetermined temperature, and the lower mold and the upper mold are A method for forming an insulator which is closed and compression-molded into a predetermined shape.