JPH0547376B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for forming a cylindrical part of a cylindrical suspension insulator suitable for use as a suspended type lightning arrester insulator with a lightning protection function by embedding a lightning arrester in the shade part. It is related to.

(Prior art) In order to prevent the insulator device from being destroyed by high voltage when lightning strikes a power transmission line, etc., a lightning arrester element with voltage non-linear characteristics, whose main component is zinc oxide, etc. is placed in parallel with the insulator. However, it is already known to release lightning voltage to the ground, as shown in, for example, Japanese Utility Model Publication No. 31456/1983. Conventionally, such lightning arresting elements were usually provided separately from the insulator, but recently attempts have been made to incorporate the lightning arresting element into the insulator shade.

However, in this case, it is necessary to provide an insulating tube in the insulator cap to house the lightning arrester, so holes are made in the raw material of the insulator cap, which has been rotary press-molded using a forming trowel called a round trowel. After firing, the holes were polished, and an insulating support tube formed and fired in a separate process was embedded in the holes, coated with glaze, etc., and then re-fired and joined. This has resulted in a disadvantage that the manufacturing process becomes complicated and the manufacturing cost increases.

Therefore, the present inventors first invented a method of integrally molding an insulator having a cylindrical part such as a lightning arrester storage part,
It was filed as Japanese Patent Application No. 1983-7205. In this method, as shown in FIG. 13, after pre-forming the socket put into a lower mold 53, an upper mold 52 having a cylindrical protrusion 51 corresponding to a cylindrical part such as a lightning arrester storage part is used.
In this method, the molded product is press-molded in a stationary state, and while the molded product is still soft, the clay remaining at the bottom of the projection 51 is removed and a hole is made in the cylindrical part that forms the lightning arrester housing part. However, insulators manufactured by this method have a marked disorder in the orientation of particles in the clay in the holes, which causes breaks in the holes, resulting in low strength in these areas, and the inner cavity of the drilled areas. It was found that there were many problems such as the need for finishing after drying.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and provides a suspension insulator having a cylindrical portion that forms a lightning arrester storage portion etc. The purpose of this work was to develop a method for forming the cylindrical part of a cylindrical suspension insulator that can be manufactured without causing any breakage by reducing the disturbance in the particle orientation of the cylindrical suspension insulator, and without the need for finishing the inner part of the hole after drying. It is something that

(Means for Solving the Problems) The present invention, which has been made to solve the above problems, has a structure in which a cylindrical core is set in a lower mold at a position corresponding to a cylindrical part forming a lightning arrester storage part. Put the clay into the core, press-form the clay using an upper mold with a cylindrical protrusion concentrically with the core, form a cylindrical part with a partition wall in the center integrally with the insulator body, and form a cylindrical blade. This method is characterized in that the inner surface of the cylindrical portion is cut together with the partition walls by the cutting method, and then the molded body is removed from the lower mold together with the core.

The present invention will be described in more detail below along with an embodiment of a method of forming a lightning arrester housing portion of a suspended type lightning arrester insulator.

(Embodiment) In a preferred embodiment of the present invention, the first
As shown in the figure, kneaded clay 1 as a raw material is molded using a rotating upper mold for molding 2 of a baking iron type and a porous lower mold 3 for molding. Next, the molded clay 1 is turned over while being adsorbed by the lower mold 3 for molding, and is placed into a porous lower mold 4 as shown in FIG.

As shown in the figure, the lower mold 4 has a recess 5 corresponding to the outer surface shape of the insulator, and a cylindrical core 6 is set at a position corresponding to the cylindrical part forming the lightning arrester storage part. It is. The core 6 is less than half the length of the lightning arrester housing, has a height that at least maintains the wall thickness that follows the shape of the cap of the insulator body, and its diameter is slightly smaller than the inner diameter of the lightning arrester housing. shall be. The lower end of the core 6 preferably has a brim shape and has a slightly larger diameter.

Next, the clay 1 goes through the preliminary pressing process shown in FIG. 3 and the preliminary forming process shown in FIG. Here, press molding is performed using a main molding upper mold 7 having a shape corresponding to the inner surface shape of the insulator. This upper mold 7 for main molding has a cylindrical protrusion 8 concentrically with the core 6 of the lower mold 4 described above. The interval formed is less than half the length of the required lightning arrester housing part to maintain a wall thickness slightly thicker than the cap wall thickness of the insulator body. When the clay 1 inside the lower mold 4 is press-molded by the upper mold 7 for main molding, a cylindrical portion 10 having a partition wall 9 in the center is formed into an insulator body 11 as shown in FIG.
It is molded integrally with. Note that the upper mold 7 for main molding is also porous, and during press molding, the molding surfaces of the upper mold 7 for main molding and the lower mold 4 for molding are both depressurized from the inside to remove air. , to obtain an accurate shape that matches the surface of each mold. After molding, the inside of the upper mold 7 for main molding is air blown to create a positive pressure with pressurized air, the upper mold 7 for main molding is separated from the molded product, and the molded product is left in the lower mold 4 for main molding. Raise the upper mold 7.

Next, as shown in FIG. 6, a cylindrical portion 10 forming a lightning arrester storage portion by a rotating cylindrical blade 12
This partition wall 9 is removed by cutting the inner surface of the partition wall 9. The diameter of the cylindrical blade 12 is slightly larger than the diameter of the press-formed cylindrical part 10, and the inner surface of the cylindrical part 10 is slightly cut.
Make sure that about 0.5 mm of clay remains on the bottom surface. In addition, since the diameter of the cylindrical blade 12 is molded to be slightly larger than the diameter of the core 6 of the lower mold 4, the inside of the cylindrical blade 12 is left uncut while the core 6 remains uncut and the partition wall 9 is cut. will remain.

Next, the cylindrical blade 12 is raised, the vacuum suction cup 13 is brought into close contact with the upper surface of the molded product as shown in FIG. 7, and the molded product is taken out from the lower mold 4 while being blown with air. At this time, since the lower surface of the cylindrical portion 10 forming the lightning arrester storage portion is covered by the core 6, the molded product is smoothly removed from the lower mold 4 together with the core 6. Then, the cut partition wall 9
At the same time, the core 6 is removed downward from the molded product to form a penetrating cylindrical portion 10. This state is shown in FIGS. 9 and 10.

Next, as shown in FIG. 8, the inner surface of the cylindrical portion 10 forming the penetrating lightning arrester housing portion is finished by a rotating trowel 14. As shown in the figure, the trowel 14 has a cylindrical shape with a large number of shallow grooves 15 in the vertical direction, and is rotated while supplying oil into these grooves 15 to obtain a smooth inner surface. Through the above steps, a suspended insulator including the cylindrical portion 10 is formed.

As described above, according to the method of the present invention, the cylindrical core 6 of the lower molding mold 4 and the cylindrical protrusion 8 of the main molding upper mold 7 form a material in the center part that is thicker than the thickness of the insulator cap part. A thin cylindrical portion 10 is molded with the somewhat thick partition wall 9 remaining. Therefore, the flow of clay in this part is illustrated as shown in FIG. 11, and the flow of clay near the surface of the vertically protruding portion of the cylindrical portion 10 is almost parallel to the surface. Therefore, the cylindrical blade 1
Even when the inner surface of the cylindrical part 10 is cut by 2,
The cylindrical blade 12 slightly cuts the flow of clay. On the other hand, the lower mold 4 without the core 6
When the cylindrical blade 12 is used to cut the inner surface of the cylindrical part 10, the cylindrical part 10 becomes thick, and the clay flows as shown in FIG. be done. As a result, according to the conventional method, cuts are likely to occur on the inner surface of the cylindrical portion 10, but according to the present invention, cuts on the inner surface of the lightning arrester housing portion 10 can be almost completely prevented.

In addition, according to the present invention, the flow of the clay near the cylindrical surface can be made almost parallel to the surface, so there is no disturbance in the orientation of the particles forming the clay within the hole, and the strength is increased. Large cylindrical part 1
You can get 0.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, a suspended insulator having an integral cylindrical portion can be produced without causing cuts in the hole, and in drying the inner cavity of the hole. It can be manufactured without the need for subsequent finishing processing. Furthermore, according to the present invention, the molded product after drilling can be taken out from the lower mold using the core with a vacuum suction cup, so that the drilling process can be performed inside the lower mold, There is no need to drill holes in the cylindrical portion in post-processing after drying as in the conventional method.

Therefore, the present invention greatly contributes to the development of industry as a method for forming the cylindrical portion of a cylindrical suspension insulator that solves the conventional problems.

[Brief explanation of the drawing]

FIGS. 1 to 8 are all cross-sectional views explaining the process of the embodiment of the present invention, FIGS. 9 and 10 are partially enlarged cross-sectional views explaining the process of making holes in the cylindrical part, and FIG. is a cross-sectional view showing the flow of clay in the cylindrical part before drilling, Figure 12 is a cross-sectional view showing the flow of clay in the same part formed by the conventional method, and Figure 13 is a cross-sectional view showing the flow of clay in the same part formed by the conventional method. FIG. 1... Clay, 4... Lower mold for molding, 6... Core,
7... Upper mold for main molding, 8... Protrusion, 9... Partition wall,
10... Cylindrical part.

Claims (1)

[Claims] 1 A cylindrical core 6 is placed at a position corresponding to the cylindrical portion 10.
The clay 1 is put into the lower mold 4 in which the mold is set, and the clay 1 is press-formed by the upper mold 7 having a cylindrical protrusion 8 concentrically with the core 6 to form a partition wall 9 in the center.
A cylindrical part 10 having a cylindrical shape is formed integrally with the insulator body, and the inner surface of the cylindrical part 10 is cut together with the partition wall 9 by a cylindrical blade 12.
A method for forming a cylindrical part of a cylindrical suspension insulator, characterized in that the cylindrical part is removed from the cylindrical suspension insulator.