GB2104171A

GB2104171A - Method of joining an insulating rod to a metal end piece

Info

Publication number: GB2104171A
Application number: GB08218607A
Authority: GB
Inventors: Jacques Bouchez
Original assignee: Ceraver SA
Current assignee: Ceraver SA
Priority date: 1981-06-30
Filing date: 1982-06-28
Publication date: 1983-03-02
Also published as: CA1207135A; FR2514546A1; FR2514546B1; IT1155704B; IT8267820A0

Abstract

A method of joining an insulating rod to a metal end piece comprises: providing a tube of ductile metal (3); inserting end portions of the rod (2) and the end piece (4) into respective ends of the metal tube; and coupling said end portions together by deforming the tube. The tube is advantageously obstructed in between said end portions, eg. by an elastomer plug (5). <IMAGE>

Description

SPECIFICATION Composite insulator and method of joining an insulating rod to a metal end piece therein The present invention relates to a method of joining an insulating rod to a metal end piece in a composite insulator. It also relates to a composite insulator obtained using the method.

A composite insulator comprises a rod of synthetic material fitted with metal end pieces. One way of fitting the end pieces to the rod is for each end piece to have a rod-receiving blind hole, and for the ends of the rod to be jammed in two such blind holes by reducing the size ofthe hole around the rod. This can be difficult to achieve when the end pieces are made of a particularly hard material such as forged steel.

The present invention avoids this difficulty.

The present invention provides a method of joining the end of an insulating rod to a metal end piece in a composite insulator, the method comprising: providing a tube of ductile metal; inserting end portions of the rod and the end piece into respective ends of the metal tube; and sleeve coupling said ends together.

The sleeve coupling may be obtained by any suitable forming process such as compression or drawing. This may be done with a machine of the kind used for putting sleeves on cables for transporting electricity, alternatively it may be done by magnetoforming orby isostatic compression using a rubber sleeve.

The tube may include mechanical reinforcement in its middle portion, in the form of ribs, for example, of an extra thickness of metal which could be made integrally with the tube or else added subsequently.

In one embodiment, a seal is disposed inside the tube in between the facing ends ofthe insulating rod and the metal end piece. The seal may be an elastomer plug inserted in the tube before the sleeve coupling operation; advantageously a neck is formed in the tube wall where it surrounds the plug by reducing the diameter of the tube.

In another variant, the seal is made of resin which is injected after the sleeve coupling operation through a hole in the wall of the tube between the ends of the rod end the end piece.

In another variant the tube may be initially obstructed in the middle by a metal washer or disk.

In order to avoid damaging the insulating rod during the sleeve coupling operation, its surface may be initially covered with a resin that acts as a lubricant before setting, or else it may be covered with a sheet of resin-impreganted glass fibre or with a layer of talc acting as a lubricant, or the like.

Two embodiments of the invention are described by way of example with reference to the accompanying drawing, in which Figures 1 and 2 are longitudinal partial sections through two respective embodiments.

In Figure 1, a tube 3 of ductile metal has been sleeve coupled both to a rod 2 of synthetic material, and to a metal end piece 1, made of forged steel for example. In Figure 1 the portion of the end piece outside the tube is shown as knob 4, but many other shapes are possible, eg. a fork, a tenon, or a ballsocket. A rubber plug seal 5 is interposed between the rod and the end piece, and the tube 3 is drawn down to form a neck 6 around the plug 5 to ensure sealing.

In Figure 2, a tube 13 is sleeve coupled both to a rod 12 and to an end piece 11 which is terminated with a fork 14. The end piece 11 has circumferential grooves 19 at its inserted end, and likewise, the rod 12 has an anchoring zone 18. A hole 17 through the neck 16 in the tube 13 serves for the insertion of resin 15 which provides sealing and also blocks the hole 17.

The present invention is particularly applicable to providing insulators for the following applications: hanging insulators, rigid insulators, line posts, phase separator arms.

1. A method of joining the end of an insulating rod to a metal end piece in a composite insulator, the method comprising: providing a tube of ductile metal; inserting end portions ofthe rod and the end piece into respective ends of the metal tube; and sleeve coupling said ends together.

2. A method according to claim 1, wherein the sleeve coupling is performed using one of the following procedures: forming; drawing; magnetoforming; and isostatic compression.

3. A method according to claim 1 or 2, wherein an elastomer plug is disposed between the facing ends of the insulating rod and the metal end piece prior to said sleeve coupling operation.

4. A method according to claim 1 or 2, wherein the tube has a hole through its wall between the facing ends of the insulating rod and the metal end piece, and wherein resin is injected via said hole to fill the space between said facing ends after said sleeve coupling operation.

5. A method according to claim 1 or 2, wherein the middle of the tube is initially obstructed by a metal disk.

6. A method according to claim 1 or 2, wherein the middle portion ofthe tube is mechanically reinforced by means of ribs, or by means of an extra thickness of the original tube-forming metal, or by means of an extra thickness of metal added to the tube.

7. A method according to any preceding claim, wherein the insulating rod is provided with a protective surface covering before being inserted into the tube, said covering being a layer of resin that serves as a lubricant before it sets, a sheet of resinimpregnated fibreglass, of a layer of talc.

8. A method ofjoining an insulating rod to a metal end piece in a composite insulator, substantially as herein described with reference to the accompanying drawing.

9. A composite insulator made according to the method of any preceding claim.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Composite insulator and method of joining an insulating rod to a metal end piece therein The present invention relates to a method of joining an insulating rod to a metal end piece in a composite insulator. It also relates to a composite insulator obtained using the method. A composite insulator comprises a rod of synthetic material fitted with metal end pieces. One way of fitting the end pieces to the rod is for each end piece to have a rod-receiving blind hole, and for the ends of the rod to be jammed in two such blind holes by reducing the size ofthe hole around the rod. This can be difficult to achieve when the end pieces are made of a particularly hard material such as forged steel. The present invention avoids this difficulty. The present invention provides a method of joining the end of an insulating rod to a metal end piece in a composite insulator, the method comprising: providing a tube of ductile metal; inserting end portions of the rod and the end piece into respective ends of the metal tube; and sleeve coupling said ends together. The sleeve coupling may be obtained by any suitable forming process such as compression or drawing. This may be done with a machine of the kind used for putting sleeves on cables for transporting electricity, alternatively it may be done by magnetoforming orby isostatic compression using a rubber sleeve. The tube may include mechanical reinforcement in its middle portion, in the form of ribs, for example, of an extra thickness of metal which could be made integrally with the tube or else added subsequently. In one embodiment, a seal is disposed inside the tube in between the facing ends ofthe insulating rod and the metal end piece. The seal may be an elastomer plug inserted in the tube before the sleeve coupling operation; advantageously a neck is formed in the tube wall where it surrounds the plug by reducing the diameter of the tube. In another variant, the seal is made of resin which is injected after the sleeve coupling operation through a hole in the wall of the tube between the ends of the rod end the end piece. In another variant the tube may be initially obstructed in the middle by a metal washer or disk. In order to avoid damaging the insulating rod during the sleeve coupling operation, its surface may be initially covered with a resin that acts as a lubricant before setting, or else it may be covered with a sheet of resin-impreganted glass fibre or with a layer of talc acting as a lubricant, or the like. Two embodiments of the invention are described by way of example with reference to the accompanying drawing, in which Figures 1 and 2 are longitudinal partial sections through two respective embodiments. In Figure 1, a tube 3 of ductile metal has been sleeve coupled both to a rod 2 of synthetic material, and to a metal end piece 1, made of forged steel for example. In Figure 1 the portion of the end piece outside the tube is shown as knob 4, but many other shapes are possible, eg. a fork, a tenon, or a ballsocket. A rubber plug seal 5 is interposed between the rod and the end piece, and the tube 3 is drawn down to form a neck 6 around the plug 5 to ensure sealing. In Figure 2, a tube 13 is sleeve coupled both to a rod 12 and to an end piece 11 which is terminated with a fork 14. The end piece 11 has circumferential grooves 19 at its inserted end, and likewise, the rod 12 has an anchoring zone 18. A hole 17 through the neck 16 in the tube 13 serves for the insertion of resin 15 which provides sealing and also blocks the hole 17. The present invention is particularly applicable to providing insulators for the following applications: hanging insulators, rigid insulators, line posts, phase separator arms. CLAIMS

9. A composite insulator made according to the method of any preceding claim.