JPH0262347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method for forming an insulator cap metal fitting, which is provided with a socket part for securing an insulator pin metal fitting, and an insulator holding skirt part. It is something.

(Prior art) In general, most cap fittings for insulators are manufactured by casting (mallable or ductile).
Only a few are forged. The reason for this is that forged insulator cap fittings are basically superior in quality and reliability compared to cast ones, but the structure of the cap fittings
This is because the socket part in particular is not suitable for forging, which increases the cost of machining and cannot compete with forgeable cap metal fittings from an economic point of view.

Conventionally, there has been a method for forging an insulator cap body (cap metal fitting) as disclosed in, for example, Japanese Patent Laid-Open No. 49-61696. This consists of a first step in which the inner and outer diameters of the top of the main body of the cap are shaped and plasticized, and a second step in which a through hole for fitting the hanging device is made on the top surface of the shaped product obtained in this first step using a punch die. a third step of shaping and plasticizing the bottom of the main body using an inner roll mold and an outer roll mold, and partitioning the bottom of the main body through the engaging edge obtained in the first step; The fourth step consisted of fitting the wall and welding the peripheral edge to the main body.

(Problems to be Solved by the Invention) However, the above-mentioned conventional method for manufacturing an insulator hat body is
A fourth process of welding a partition wall to the engaging edge for each product is required, resulting in low work efficiency, making it impossible to reduce product costs, requiring an inspection process for the welded area, and further reducing the reliability of the welded area. There was also a problem.

In addition, in the conventional method for manufacturing an insulator hat body, a second step is performed in which a punch die is used on the top surface of the shaped product to create a through hole for fitting a hanging device such as a pin fitting, thereby making it possible to create an insulator hanging device that requires strength. There was a problem in that the grain flow lines in the wall forming the engagement recesses that engage were cut, resulting in reduced strength, wasted material, and increased product cost.

(Means for solving the problems) In order to solve the above-mentioned conventional problems, the first invention includes:
The material is forged by an upper mold and a lower mold into a cylindrical skirt portion with an open outer end and a cylindrical engagement wall portion with an open outer end and one side thereof, and the above-mentioned A first step of integrally forming a partition wall at the boundary between the skirt portion and the engagement wall, and further pressing the engagement wall from above and below to curve the tip of the engagement wall inward. The second step is to form an engagement recess by bending the skirt portion, and the third step is to curve the lower end of the skirt portion inward to form a retaining prevention protrusion.

In addition, the second invention solves the above-mentioned conventional problems, and in order to accurately mold the engaging recess, the material is formed into a cylindrical skirt portion with an open outer end using an upper mold and a lower mold, and the outer end is is forged into a cylindrical engagement wall with an open side, and a curved annular step with a rapidly changing wall thickness is formed on the outer periphery of the middle part of the engagement wall. , a first step of integrally molding a partition wall at the boundary between the skirt portion and the engagement wall, and further pressing the engagement wall from above and below to curve the tip of the engagement wall. a second step of curving inward around the annular stepped portion to form an engagement recess; and a third step of curving the lower end of the skirt portion inward to form a retaining prevention protrusion. I am adopting a method.

(Function) In the first invention, by adopting the above-mentioned means, the partition walls are integrated, and the engagement recess is formed by curving the engagement wall portion without cutting it in the direction perpendicular to the grain flow line. Therefore, the strength of the product increases, and welding work becomes unnecessary, improving productivity.

Moreover, the second invention, in addition to the effects of the first invention,
The engagement wall portion is accurately curved inward during forging, centering on the curved annular step, and the shape of the engagement recess is accurate.

(Example) Hereinafter, an example embodying the present invention is shown in Figs.
This will be explained based on FIG. 17.

First, a long round bar is cut into a predetermined length to form a cylindrical material 1 as shown in FIG.

Next, the same material 1 is pressed from above and below by upper and lower forging dies (not shown) to forge a flat material 2 having a protrusion 2a at the center of the lower surface as shown in FIG.

After that, as shown in FIGS. 3 to 5, the upper mold 3,
The raw material 2 is forged into the cavity shape of the same mold using a forging mold consisting of a lower mold 4, a core 5, and an extrusion knock pin 6 to form a cap metal fitting 18, which will be described later.
The original form 7 is formed. During molding of this original form 7, a horse-shaped engagement wall part 7b having an opening 7a on one side is formed at the lower end of the original form 7, as shown in FIG. 4, and a cylindrical skirt is formed at the upper part. A partition wall 7d is integrally formed at the boundary between the engaging wall portion 7b and the skirt portion 7c.

Next, as shown in FIGS. 6 to 8, the original form 7
, upper mold 8, lower mold 9, core 10 and knock pin 1
1, the engaging wall portion 7b is made high by forging it into a cavity shape using a forging die, and an annular step portion 7e having an L-shaped cross section that bulges outward is formed on the entire circumference of the hem portion of the skirt portion 7c. , the partition wall 7d is made thin. Further, a curved annular stepped portion 7f whose thickness changes rapidly is formed on the outer periphery of the intermediate portion of the engagement wall portion 7b.

Thereafter, as shown in FIGS. 9 to 11, the upper mold 13, the lower mold 14, and the lower mold 1 fixed to the mounting member 12
A forging die consisting of a lower mold 15 and a core 16 fitted into the lower part of the original shape 7 is used to curve the lower half of the engagement wall portion 7b of the original shape 7 inward around the curved annular step portion 7f, An engagement recess 7g is formed inside the wall 7b. As shown in FIG. 12, the lower mold 15 is formed with a molding surface 15a in the shape of an inverted truncated cone, and a recess 15b is cut out from the center to the side of the molding surface 15a, and the recess 15b has an opening. The molding core 16 of 7a is inserted so as to be slidable in the vertical direction.
Then, during forging, the engaging wall portion 7b is curved inwardly around the curved annular step portion 7f by the forming surface 15a.

Next, as shown in FIGS. 13 to 16, in place of the lower mold 15 and the core 16, a lower mold 15A with a curved molding surface 15a, and a curved molding surface 16 are used.
Using the core 16A in which a is formed, the original shape 7 is
The outer surface of the engaging wall portion 7b is rounded. After the mold is released, a hole 7h for passing a pin is drilled in a part of the engaging wall portion 7b, as shown in FIG. 15.

Finally, lower molds 12', 1 as shown in FIG.
3', and press the upper surface S of the annular stepped portion 7e with an upper mold 17 having a bore that contacts at least the outer side of the hem of the skirt portion 7c, so that the annular stepped portion 7e is centered around its base E. curve inward. In this way, two upper and lower levels of retaining ridges 7i are formed on the inner circumferential surface of the hem portion of the skirt portion 7c.

Note that since the engaging recess 7g is forged, its dimensional accuracy is not high, so the surface may be finished by a milling cutter if necessary, but in this case, it is cut parallel to the grain flow line. , there is almost no problem in terms of strength.

The manufacturing of the cap fitting 18 is completed through the steps described above. Cap fitting 18 thus obtained
is fitted and fixed, for example, to the head 19a of the suspension insulator 19 with cement 20, as shown in FIG. A pin fitting 21 fixed to the lower part of another suspension insulator 19 is engaged with the engagement recess 7g in the upper part of the cap fitting 18.

Note that the present invention can also be embodied in the following embodiments.

(1) As shown in FIG. 19, the above-described material 1 is pressed to form a thick material 2A having a recess 2b on the upper surface.
form. As shown in FIG.
Next, as shown in FIG. 21, a forging die consisting of an upper die 26, a lower die 27, a core 28, and a knock pin 29 is used to form the original shape 7A. Engagement wall portion 7b of the original form 7A
and raise the skirt portion 7c. The subsequent forging process is almost the same as the process described above, but in this other example, the material 2A is not made extremely flat, so the forge flow lines are not strained and the strength is excellent.

(2) In the above embodiment, two upper and lower retaining prevention protrusions 7i were formed, but the hem of the skirt portion 7c at the forging stage shown in FIG. 3 is simply curved to form only one protrusion 7i. thing.

(3) In the embodiment described above, the curved annular stepped portion 7f was formed, but an embodiment in which this forming step is omitted constitutes an embodiment of the first invention.

Effects of the Invention As detailed above, the first invention improves productivity and strength by integrally molding the partition wall of the cap metal fitting, and improves the strength by cutting the grain flow line on the upper surface of the engaging wall. This has the effect of improving reliability by eliminating waste, and reducing product costs by eliminating waste of materials.

Moreover, the second invention has, in addition to the effects of the first invention,
This has the effect of accurately curving the engaging wall portion around the curved annular stepped portion forming the engaging wall portion, increasing the molding precision of the engaging recess, and improving the quality of the product.

[Brief explanation of drawings]

Figures 1 and 2 are front views of the material, Figure 3 is a sectional view showing the forging process of the original cap metal fitting, Figure 4 is a bottom view of only the original shape, and Figure 5 is a partial sectional view of the original shape. Fig. 6 is a sectional view showing the forging process of the original cap metal fitting, Fig. 7 is a bottom view of the same original only, Fig. 8 is a partial sectional view of the same original, and Fig. 9 is a cross section showing the forging process of the original cap metal fitting. Figure 10 is a bottom view of only the original shape, Figure 11 is a partial sectional view of the original shape, Figure 12 is an exploded perspective view of the lower mold and core, and Figure 13 shows the forging process of the original cap metal fitting. Cross section, 14th
The figure is a bottom view of only the same original form, Fig. 15 is a partial sectional view of the same original form, Fig. 16 is an exploded perspective view of the lower mold and core,
Fig. 17 is a cross-sectional view showing the forging process of the retaining ridge, Fig. 18 is a cross-sectional view showing how the cap metal fitting is used, and Fig. 19 is a cross-sectional view of the material showing another embodiment of the present invention. FIG. 20 is a cross-sectional view showing the forging process of the original cap metal fitting, and FIG. 21 is a cross-sectional view showing the forging process of the original cap metal fitting. 7,7A...original form, 7a...opening, 7b...
Engagement wall part, 7c... Skirt part, 7d... Partition wall, 7e... Annular step part, 7f... Annular step part for curving, 7g... Engagement recessed part, 7i... Retention prevention protrusion, 18 ...Cap metal fittings.

Claims (1)

[Scope of Claims] 1. A cylindrical skirt portion whose outer end is open using an upper mold and a lower mold, and a cylindrical engagement wall portion whose outer end is open and one side thereof is open. a first step of integrally forming a partition wall at the boundary between the skirt portion and the engaging wall portion; It is characterized by comprising a second step of curving the tip inward to form an engagement recess, and a third step of curving the lower end of the skirt portion inward to form a retaining prevention ridge. A method for forming cap fittings for insulators. 2 The material is forged into a cylindrical skirt part with an open outer end and a cylindrical engagement wall part with an open outer end and one side opened, using an upper die and a lower die. a first step of forming a curved annular stepped portion with a rapidly changing wall thickness on the outer periphery of the intermediate portion of the mating wall portion, and integrally molding a partition wall at the boundary portion between the skirt portion and the engaging wall portion; a second step of pressing the engagement wall from above and below to curve the distal end of the engagement wall inward around the curved annular step to form an engagement recess; A method for forming an insulator cap fitting, comprising a third step of curving the lower end of the insulator inward to form a retaining ridge.