US2014441A - Insulator and method of assembly - Google Patents

Description

Sept. 17, 1935. G. A. MATTHEWS INSULATOR AND METHOD OF ASSEMBLY Filed Feb. 2, 1933 Patented Sept. 17, 1935 UNITE stares re n 2,014,441 INSULATOR, ANDMETHOD 0F ASSEMBLY (George A. Matthews, Detroit, Mich. Application February 2, 1933, Serial No. tamer 3 Claims. (0119482)" The present invention relates in general to insulators and is particularly concerned with the details of construction of insulator hardware and fittings, and a novel method of securing the fit- 5 ting to the insulating medium.

In the prior art constructions, it has in the main, been the custom to utilize one of two'principal methods for securing caps, bases and other fittings of metallic material to an insulating body of such material as porcelain, glass and the like. In one of these arrangements, the metal hardware is cemented. to the porcelain whereas in the other arrangement the hardware is secured with the metal in direct contact with the insulating onto the insulating medium, casting the insulating medium in the fitting during the molding process, and by various other ways which are well known in the art.

The arrangement wherein the metallic fitting is cemented to the insulating medium has proved unsatisfactory due to the difference in the coeificients of expansion between the metal and the insulating medium. This reaction to the changes of temperature causes the cement to crack and deteriorate, the result being that the'operating characteristics of the insulator are decreased to such an extent that it must either be repaired or replaced; Moreover, this arrangement is objectionable in that the dehydration of the cement results in an inferior joint between the insulating medium and the fitting.

' In the other arrangement wherein the metal is in direct contact with the insulating medium,

the different coefficients of expansion of the metal and insulating substance is apt to cause cracking of the insulator or loosening of the joint. Further, it has been found to be very difiicult to shrink the metal aboutthe insulating 40 a medium and form a tight joint, since the shrinking process is apt to result in damage to the insulating substance. Moreover, the arrangement wherein the insulator ismolded into the fitting is subject tn the same inherent disadvantages as in the other cases where the metal fitting is in direct contact with the insulating medium.

With the foregoing in mind, the present invention seeks to overcome the disadvantages of the prior art constructions, and to' this end proposes to secure the metal fitting to the insulating medium in such a manner that a substantially rigid joint will be attained, and which at the same time will be sufliciently flexible to enable 55 the insulating medium and the metallic fitting medium, either by clamping, shrinking the metal to individually respond to temperature changes withoutimpairing the joint between the insulating medium and the metallic fitting. v v It is therefore a principal object of the present invention to provide a simple and novel means 5,

whereby an insulating medium such as porcelain, glass and the like may be secured to a metallic member.

It is a further object of the present invention to provide improved means for joining a metallic 10 member and insulating medium such as glass, porcelain and the like, which are so constructed and designed as to form a fluid tight joint therebetween. It is a further object of the invention to provide an improved support for an insulating 15 body and novel connecting means for connecting the insulating body and support in such a manner as to form a flexible and-fluid tight joint therebetween. v

It is a still further object of the invention to 20 provide an improved method for securing a metallic fitting to an insulating medium of glass, porcelain and the like.

V In accordance with the general features of this invention, it is proposed to provide an in- 5 sulating medium of porcelain, glass and the like having a portion which is substantially cylindrical in shape. The surface of this portion is grooved or otherwise roughened and surrounded with a layer of resilient material such as rubber. 0 The fitting is constructed with a band or collar portion which is placed around the resilient material, after which the band or collar '18 spun or rolled so as to conform to the grooves or other irregularities in the surface of the cylindrical portion of the insulating medium. rolling or spinning of the metal causes the resilient layer to also conform to the irregularities of this surface and seal the space between the metal and I the insulating medium, whereby a substantially rigid andfluid tight joint is attained between the metal and the insulating medium, the resilent layer of material enabling the insulating medium and metal to physically respond to changes" in temperature without impairing the joint therebetween.

Other objects and features of this invention willmore fully appear from the following detailed description taken in connection with the accompanying drawing which illustrates a single embodiment thereof, and in which:

Figure 1 is an enlarged elevation partly in section of an insulator assembly embodvin he present invention; and

Figures 2 and 3 illustrate different steps in the 55 method of securing a metallic fitting to an insulating medium in accordance with this invention.

As shown on the drawing:

As illustrative of the present invention, there is disclosed in Figure 1 an insulator assembly which embodies the features of the invention. This insulator assembly comprises an elongated body- ID of insulating material such as porcelain, glass and -the like, which in this instance has a central opening II to enable a conductor to be carried therethrough. Although the invention is shown in connection with a hollow cylindrical insulating body, it will be apparent to those skilled in the art that it may with equal facility be applied to a solid insulating body such as maybe used in connection with a bus support and the like.

The insulating body I!) is formed adjacent its lower end with a cylindrical portion l3 which is circumferentially grooved adjacent its end extremities as shown at M.

The insulating body is supportedby means of a bracket fitting generally indicated by the numeral I5. This fitting comprises a sleeve portion l6 which is disposed circumferentially around the cylindrical portion l3 of the insulating body and terminates at its upper end in an outwardly extending flange IT and at its lower end in an outwardly extending flange l8. Intermediate the flanges l1 and I8, the sleeve I6 is provided with circumferentially extending grooves l9 which are so positioned as to overlie and be in registration with the grooves M of the cylindrical portion [3 of the insulating body.

The sleeve I6 of this supporting bracket, it will be observed, is not in direct contact with the cylindrical portion of the insulating body but in cushioned thereon by means of circumferentially extending gaskets which are disposed between the grooved portions of the sleeve and the grooved portions of the insulating body, the grooves of the sleeve compressing these gaskets into the grooves of the insulating body. Although the drawing discloses an individual gasket for each groove, it will be apparent that a single sleeve of elastic material such as rubber and the like may be disposed around the cylindrical portion of the insulating body between this portion and the metallic sleeve. It will be apparent that this arrangement interlocks the metallic fitting to the insulating body and produces a substantially rigid joint therebetween which is fluid tight, thereby enabling this arrangement to be eifectively used where the joint is to be submitted to fluid pressure.

The downward thrust of the above described insulating body is additionally resisted by the flanged portion ll of the sleeve of the fitting, this flange being in engagement with a resilient gasket 2| which is disposed between the flange I1 and the lowermost petticoat of the insulating body.

The annular flange l8 may be provided with a plurality of apertures for receiving therethrough bolts 22 for securing the fitting to a supporting structure such as shown at 23.

From the above description, it will be apparent that fittings for the upper end of the insulating body may be secured thereto in the same manner as just described in connection with the supporting bracket. The upper end of the insulator is similarly provided with a cylindrical portion 24 which is circumferentially grooved as shown at 25. In this particular instance, a terminal connection generally indicated at 2B is shown as being secured at the upper end of the insulating body. This fitting includes a cap portion 21 which is adapted to fit over the end of the insulating body and embrace the circumferentially grooved por- 0 tion 24. This cap is circumferentially grooved as shown at 28 in the-same manner as in the case of the sleeve l6 previously described, the cap grooves and the grooves of the insulating body being separated by gaskets of resilient material as shown 10 at 29. It has also been found desirable to provide a resilient gasket 30 between the upper end of the insulating body and the top portion of the cap.

It will be apparent that, although inwardly ex- 15 tending grooves are disclosed on the insulating body and the metallic fittings, any number of grooves maybe used and that these grooves may be of any desired shape, and further, that the grooves may extend outwardly rather than inwardly, the purpose of these grooves being to in terlock the metallic fittings and the insulating body against axial relative movement, except insofar as flexibility is permitted by the resilient gasket. While the invention in its broad aspectcontemplates that these grooves may be of any desired shape, it' is preferable that the grooves of both the insulating medium and the metallic fitting 0 shall be of such shape as to not be readily affected by changes in temperature of the medium containing the grooves. Moreover, the grooves in the metallic fittings and the grooves in the insulating medium are preferably disposed relative to each other in such a manner that ii any expansion should occur in one relative to the other, the joint will not be impaired and the insulating medium and metallic fitting are free to respond individually. 40

It will also be apparent that, where the insulating medium is to be used in connection with a container having a liquid such as oil therein, the lower end of the fitting may be formed so as to extend past the lowermost gasket and cooperate r with the insulating medium to form an air pocket or space as shown at 29a. Should the liquid in the container rise to such an extent as to reach the lowermost gasket, air will be entrapped in the space 29a and prevent the liquid from com- 0 ing in contact with the gasket.

The method of assembling the insulating body and fittings, and the manner in which a fitting is secured to the insulating body will be more fully understood by reference to Figures 2 and 3.

It is thought that the description of the method of securing the cap fitting to the insulating body will be sufficient to enable the method to be practiced in securing other fittings to the insulating body. It is therefore not deemed necessary to describe the method in connection with the supporting bracket.

The fitting 26 as previously described is provided with a cap portion, this portion initially being a plain surface without grooves therein as 5 shown in Figure 2. The fitting is inserted over the end of the insulating body with the side portion 21 extending over the grooves 25 and with the resilient gaskets disposed between the metal and insulating body.

A mandrel 3! as shown in Figure 3 is inserted within the insulating body in order that the body and fitting may be revolved together. The metal comprising the side portion of the fitting is then spun or rolled by a tool as indicated at 32, this tool being so formed as to produce the circumferential grooves in the metal'during the working operation.

It will be observed, as shown in Figure 3 that as the spinning operation progresses, the metal is pushed into the grooves in the insulating body and the resilient gaskets are, moreover tightly compressed between the metal and the insulating material. In this manner, a substantially rigid insulating medium such as porcelain or glass may be secured to a metallic fitting; which is so constructed and designed as to form a fluid tight joint, which enables the insulating medium and metallic fitting to individually respond to temperature changes without impairing the joint therebetween; and an improved method for securing the metallic fitting to an insulating medium.

Now, it is of course to be understood that although I have described in detail the preferred embodiment of my invention, the invention is not to be thus limited only insofar as defined by the scope and spirit of the appended claims.

I claim as my invention:

1. In the method of supporting a porcelain insulator and in assembling said insulator with a metallic support to make said metallic support substantially integral with said insulator but in spaced and fluid tight relation to the porcelain thereof, the steps of providing an elongated cylindrical portion of said porcelain insulator with an irregular surface, placing a layer of an elastic material, such as rubber, over said irregular surface, telescoping a cylindrical metallic sleeve having a pair of outwardly extending terminal flanges over said layer. of elastic material, spinning the metal of the sleeve to cause it and the layer of elastic material to substantially conform to the surface of said cylindrical portion of said insulator and thereby make said sleeve a substantially integral part of said insulator, and securing one of said flanges to a support to thereby support the assembled insulator and sleeve as a unit.

2. In the method of forming a porcelain insulator and a metallic support therefor into a single unitary structure by making the support a substantially integral part of the insulator but in spaced and fluid tight relation thereto, the steps of providing an elongated and cylindrical portion of said porcelain insulator with an irregular sur= in face, placing a layer of an elastic material, such as rubber, over said irregular surface, providing an outstanding annular boss on said insulator, telescoping a metallic bobbin having upper and lower outstanding terminal flanges over said layer 15 of elastic material, placing a gasket of non-metallic material between the upper flange of said bobbin and said outstanding boss, spinning the metal of said bobbin to cause it and the layer of elastic material to substantially conform to the surface 20 of said cylindrical portion and make said bobbin an integral part of said insulator and whereby the resulting unitary structure is supportable as a unit by resting only said lower flange on a support. 26

3. The method of connecting a metallic supporting member to a porcelain insulator through an elastic bond whereby said metallic member is made substantially integral with said insulator and whereby the resulting unitary structure is 30 adapted for support as a unit by securing only said metallic member to suitable external supporting means, said method comprising providing a cylindrical portion of said porcelain insulator with an irregular surface, placing a layer of an elastic material, such as rubber, over said roughened surface, telescoping a metallic sleeve over said layer of elastic material, spinning the metal of said metallic sleeve to cause it and the layer of elastic material to substantially conform to the surface of said cylindrical portion and make said sleeve an integral part of said insulator, and providing said sleeve with an integral outstanding member whereby said insulator and sleeve are adapted to be supported as a unit when only said outstanding member is secured to external supporting means.

- GEORGE A. MATTHEWS.

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