JPH0262348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a method of forming an insulator cap metal fitting having an engaging recess for engaging 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
In particular, since the engaging recess is not suitable for forging, the cost of machining increases, and from an economical point of view, it cannot compete with castable cap metal fittings.

Conventionally, there has been a method for forging insulator caps (cap fittings) 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 formed, 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. 2nd step, a 3rd step in which the hem of the main body obtained in the above 1st step is shaped and plasticized using an inner roll die and an outer roll die to form a retaining ridge, and a 1st step. The method consisted of a fourth step of fitting the partition wall into the main body via the engagement edge thus obtained, 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 step is required to weld the partition wall to each product to the engagement edge, which results in low work efficiency and makes it impossible to reduce the cost of the product.An inspection process for the welded part is also required, and the reliability of the welded part is reduced. There was also a problem.

In addition, in the conventional method for manufacturing an insulator cap 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 producing an insulator hanging device that requires strength. There was a problem in that the grain flow lines in the wall forming the engagement recess that engages were cut, reducing the strength, wasting material, and increasing the cost of the product.

Furthermore, in the conventional manufacturing method, in the third step, the hem of the main body is strongly pressed by the inner roll die and the outer roll die to form the retaining ridges, so a rotation drive device for the insulator cap body is required. , productivity decreases,
Also from this point of view, there is a problem that it is not possible to reduce the cost of the product.

(Means for Solving the Problems) In order to solve the above-mentioned conventional problems, the present invention uses an upper die and a lower die to form a material into a cylindrical skirt portion with an open outer end. and a cylindrical engagement wall portion with one side open, and a first step of integrally molding a partition wall at the boundary between the skirt portion and the engagement wall portion; a second step of pressing the mating wall portion from above and below to curve the tip end of the mating wall portion inward to form an engaging recess; and from the first step to the second step or after the second step. , a third step of forming an annular stepped portion that bulges outward at the hem of the skirt portion; and a third step of forming an annular stepped portion that bulges outward at the hem of the skirt portion, and curving the annular stepped portion inward around its base to form two steps on the inner peripheral surface of the hem of the skirt portion. A method is adopted which includes a fourth step of forming a retaining protrusion.

(Function) By employing the method described above, the present invention allows the partition walls to be 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. This increases the strength of the product, eliminates the need for welding work, and eliminates the need for a rotary drive device for the cap fittings, improving productivity.

(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 a knock pin 6 for extrusion to form a cap metal fitting 1, which will be described later.
Form the original form 7 of 8. 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. A skirt portion 7c is formed, and a partition wall 7d is integrally formed at the boundary between the engagement 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
The engagement wall portion 7b is made taller by forging into the cavity shape using a forging die consisting of 1, and
An annular stepped portion 7e having an L-shaped cross section that bulges outward is formed around the entire circumference of the bottom portion of the skirt portion 7c, and the partition wall 7b 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 presses 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, thereby forming the annular stepped portion 7e with its base E as the center. curve inward. In this way, the upper and lower two stages of retaining ridges 7i are formed on the inner circumferential surface of the hem portion of the skirt portion 7c.

Since the engaging recess 7g is forged, its dimensional accuracy is not high, so the surface may be finished with 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.
The original shape 7A is formed by molding into the capi- ty shape using a forging die.

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 engaging wall portion 7b of the original shape 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 flow line of the forging is not strained and the product has excellent strength.

(2) In the embodiment described above, the projections 7i are formed by pressing the upper surface S of the annular stepped portion 7e, but instead of this, the outer surface of the stepped portion 7e may be pressed inward.

(3) In the embodiment described above, the annular stepped portion 7e was formed in the step shown in FIG.
This must be done before forming the retaining prevention protrusion 7i shown in the figure.

Effects of the Invention As detailed above, the present invention integrally molds the partition wall of the cap metal fitting at the same time, eliminates the need for a rotary drive device for the cap metal fitting, increases productivity, improves strength, and improves the engagement wall part. It is possible to improve reliability by eliminating the need to cut the grain flow lines on the upper surface of the machine, and also to reduce the cost of the product by eliminating waste of materials.

[Brief explanation of the drawing]

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)

[Claims] 1. Forging the material into a cylindrical skirt part with an open outer end and a cylindrical engagement wall part with an open outer end and one side thereof opened, using an upper die and a lower die, and 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 move the tip of the engagement wall inward. a second step of curving to form an engagement recess; and a third step of forming an annular stepped portion that bulges outward at the hem of the skirt portion after the first step to the second step or after the second step. and a fourth step of curving the annular stepped portion inward around its base to form a two-stage slip-off prevention ridge on the inner peripheral surface of the hem of the skirt portion. How to form cap metal fittings.