US3502792A - High voltage electrical insulator - Google Patents

Description

March 24, 1970 D. o. MISARE HIGH VOLTAGE ELECTRICAL INSULATOR Filed July 5, 1968 IJvEN oR Dor ALD O. MlARE ATTO NEjS.

United States Patent O 3,502,792 HIGH VOLTAGE ELECTRICAL INSULATOR Donald 0. Misare, Riverside, lll., assigor to Joslyn Mfg. and Supply Co., Chicago, Ill., a corpo'ation of Illinois Filed July 5, 1968, Ser. No. 742,758 Int. Cl. H01b 17/40 U.S. Cl. 174-188 3 Claims ABSTRACT OF THE DISCLOSURE An electrical insulator comprising a body of insulating material having a circular end face and retaining surface spaced inwardly on the *body from the end face. A terminal member of conducting material having a cuplike shape with an end wall facing the end face of the insulating body and a skirt portion outwardly of the body telescoped over the end portion of the body. The skirt includes an outer edge portion which is deformed in a spinning operation forcing the metal inwardly toward the center of the insulator body to bear tightly against the retaining surface thereof. An annular spring Washer is disposed between and exerts pressure against the end face of the insulator body and the end wall of the terminal means holding the deformed edge portion of the skirt tightly against the retaining surface and preventing rotation of the terminal means on the body.

In prior electrical insulators employing an insulator body of material such as glazed porcelain and a metal terminal mounted on one end of the body, many problems have arisen in providing suitable means for mounting and securing the metal terminal on the insulator body in a successful manner so as to readily accommodate relative expansion and contraction of the body and terminal caused 'by variations in weather conditions and temperature. One attempted solution is the use of resilient neoprene scaling gaskets or the like between the terminal and the insulator body material; however, the gaskets are generally unsatisfactory because of cold flow of the gasket material. The cold flow of the gasket material permits some relative movement between the confronting faces of the metal terminal and the insulator body resulting in the terminal becoming loosened on the body. Such loose terminals are a frequent source of radio interference when the insulator is subjected to high voltage stress and, in addition, such loosened terminals make it difficult for linemen to install the terminals in place and make connections thereto as well as make it diflicult to disconnect lines from terminals already installed. If the insulators have been stored for periods of time before installation, oftentimes during the storage period cold flow of the gasket material occurs and the lineman has difi'iculty in making the initial installation of the insulator and connecting lines to the terminal thereof. Such conditions generally necessitate the use of a wrench or other holding tool applied to the body of insulating material and oftentimes this results in breakage, cracking, or chipping of the insulator body, especially where porcelain or other more or less brittle materials are used for the body.

It is therefore an object of the present invention to provide a new and improved electrical terminal.

It is another object of the present invention to provide a new and improved method ofmaking an electrical terminal of the character described.

It is another object of the present invention to provide a new and improved electrical insulator of the character described employing new and improved means for se- 3,50Z,79Z Patented Mar. 24, 1970 ice a new and improved electrical terminal assembly for an electrical insulator which provides for a positive and tight mounting connection of the terminal on the insulating body so that no radio interference will occur.

Another object of the present invention is the provision of a new and improved electrical insulator of the type described which eliminates the need for a resilient sealing gasket between the terminal and the insulating body portion.

Another object of the present invention is the provision of a new and improved electrical insulator having means for preventing the terminal from loosening on the insulating body and therefore causes fewer problems for a lineman during installation of the insulator in the field and when making connections to or disconnecton from the electrical terminal of the insulator.

Another object of the present invention is to provide a new and improved electrical insulator wherein a lineman, when making a connection to or a disconnecton from the terminal, is not required to use wrenches or other holding devices applied to the body of the insulating material.

Another object of the present invention is to provide a new and improved method of making an electrical insulator of the character described which is rapid, low in cost, and which lends itself readily for mass production of said insulators.

Another object of the present invention is to provide a new and improved method of making an electrical insulator of the character described wherein the metal terminal portion is deformed in a spinning operation to firmly mount and connect the terminal to the insulator -body ina manner to accommodate relative expansion and contraction of the terminal and insulator body, due to temperature changes, without loosening of the terminal on the body or breakage or damage to the components of the insulator.

Another object of the present invention is the provision of a new and improved electrical insulator of the character described which does not require the formation of keyways, threads, or other torque resisting means on the insulator body itself, thus resulting in a lower cost in formng the insulator body and assembling the terminal thereon.

Another object of the present invention is to provide a new and improved electrical insulator of the character described which Will withstand extreme variations in weather conditions and temperature for long periods without having the terminal 'become loosely mounted on the insulator body.

These and other objects of the present invention are accomplished in one illustrative embodment thereof comprising an `electrical insulator including a body of insulating material, such as glazed porcelain or the like, having a circular end face and retaining surface spaced inwardly on the body from the end face. A terminal member of conducting metal having an end wall facing the end face of the insulator body and an annular skirt or wall portion outwardly.thereof is telescoped onto the body and extends between the end face and the retaining surface, and the outer edge portion of the skirt is deformed inwardly towards the center of the body against the retaining surface to firmly and securely hold the terminal in place. An annular spring washer means is disposed between the end face of the insulator body and the end wall of the terminal means to exert pressure therebetween, thus positively holding the deformed edge portion of the skirt tightly against the retaining surface on the body and thereby preventing loosening of the terminal and/or relative rotation between the terminal and the body.

The spring washer means permits relative expansion and contraction of the respective components of the insulator yet continuously maintains a secure and tight mounting connection of the terminal on the insulatng body portion.

In accordance with the method of the invention, the skirt of the terminal is slipped onto the end portion of the insulator body over the spring washer means, and the end wall is compressed toward the body end face, thereby exerting compression on the spring washer means. While compression is maintained, the skirt of the terminal is deformed inwardly against the retaining surface of the insulator body in a metal spnning operation, and the clamping pressure is subsequently released after the spnning operation is complete. The spring washer then exerts continuous pressure between the insulator body and the end wall of the terminal, thereby preventing relative rotation between the terminal and positively securing the terminal in a tight mounting connection. The washer permits expansion and contraction of the respective terminal and body when the insulator is subjected to extreme variations in temperature and weather conditions, yet still maintains a tight mounting connection of the terminal on the body.

For a better Understanding of the present invention, reference should be had to the following detailed description taken in conjunction with the drawings, in which:

FIG. 1 is a side elevational view of a new and improved electrical insulator constructed in accordance with the features of the present invention;

FIG. 2 is a longtudinal sectional View through the insulator of FIG. 1 taken substantially along line 2-2 thereof;

FIG. 3 is a fragmentary portion in section illustrating the terminal member, spring washer, and end portion of the insulator body before the terminal skirt is deformed by spnning to secure the terminal in place on the body; and

FIG. 4 is an exploded perspective view, with portions cut away, of the new and improved insulator of FIG. 1.

Referring now, more specifically, to the drawings, therein is illustrated a new and improved electrical insulator of the stand-off type especially adapted for outdoor, high voltage applications and constructed in accordance with the features of the present nvention. The insulator 10 includes an elongated body portion 12 constructed of insulatng material, such as glazed porcelain or the like, and the body is of a generally cylindrical shape including a plurality of annular rngs or ridges 14 thereon, intermediate the opposite ends. The upper end of the insulator body 12 includes a flat, annular end face 16 which forms one side of an annular end ridge or ring 18 having an outer peripheral surface 20 and an annular opposite side forming a retaining surface 22. The lower end of the insulator body includes an opposite annular end face 24 defining one side of an annular ring or ridge 28 having a peripheral surface 29 and an opposite side forming an annular retaining surface 30.

If a male type terminal assembly is to be mounted on the upper end of the insulator body 12, a shallow recess or hollow 32 is formed to extend axially inward -from the end of the body within the annular end surface 16, and in the lower end of the body a similar but deeper recess 34 is formed to accommodate a female type terminal assembly. If male terminals are to be mounted on both ends of the insulator body or female terminals, the recesses 32 and 34 can be identical in depth. However, in the customary application a male type terminal is usually provided at the upper end and a female type terminal mounted at the lower end thereof so that the insulator can be connected in series end-toend relation if desired.

The electrical insulator 10 includes an upper terminal assembly 40 of the male type and a lower terminal assembly 50 of the female type. The upper terminal assembly 40` includes a cuplike, metal terminal member having a circular end wall 42 at the upper end and an integrally formed downwardly depending annular skirt or sidewall 44. The end wall 42 is provided with several eccentrically positioned, upstanding, integrally formed bosses 42a thereon for aiding in preventing rotation of electrical components connected to the terminal, and a central, circular opening 46 is formed in the end wall to accommodate the lower end portion of a threaded terminal stud 48 having an enlarged head 48a at the lower end which is brazed, welded, or otherwise permanently fastened to the lower surface of the end wall. Preferably, the upper terminal member is fabricated from corrosion resistant material, such as stainless steel or the like, in a drawing or spnning process, and the material used should be suitable for forming and shaping in a metal spnning operation.

In accordance with the present invention, an annular frustoconical, "Belleville type spring washer 60 is inserted between the upper end face 16- of the insulator body 12 and the lower surface of the end wall 42 of the cuplike terminal member to provide spacng therebetween to accommodate expansion and contraction. Referring to FIG. 3, in assembling the cuplike terminal member onto the upper end portion of the insulator body 12, the "Belleville washer 60 is first placed on the end surface 16 and the cuplike terminal member is telescoped onto the insulator body with the skirt 44 extending downwardly and encircling the outer peripheral surface 20 of the end ridge 18 on the insulator body. Downward thrust is then applied to the terminal assembly 40 forcing the end wall 42 downwardly toward the end face of the insulator body and compressing the Belleville" washer 60 from a relaxed or normal position (FIG. 3) to a compressed condition (FIG. 2). While the "Belleville washer is thus compressed, the body 12 and the upper terminal assembly 40 are rotated together about the longtudinal axis of the insulator in a spnning chuck, and a spnning tool is applied to the lower edge portion 44a of the terminal skirt 44 to deform the skirt inwardly against the retaining lower surface 22 of the end ridge 18 on the insulator body. After the deformaton of the skirt has been accomplished as described (FIG. 2), the external axial clamping pressure on the end wall 42 of the terminal member is released and the washer 60' tends to return to its normal noncompressed condition (FIG. 3), thereby exerting continuous pressure between the end face 16 of the insulator body and the end wall 42 of the termnal assembly 40. This pressure insures that the lower deformed skirt portion 44a is securely held against the retaining annular surface 22 on the insulator body and positively prevents rotation of the terminal member on the insulator body. When a lineman s applying nuts or suitable connecting hardware to the threaded stud 48, the terminal assembly 40 is securely maintained against rotation on the body 12, thereby eliminating means for clamping or holding the body itself against rotation. As the component parts of the terminal assembly and the insulator expand and contract during temperature variations, the "Belleville washer 60 expands and contracts accordingly, but continuously eXerts end force between the end face 16 of the insulator body and the end Wall 42 of the terminal, thus preventing the terminal from loosening on the ridge portion 18 of the body. The mounting connection thus made between the insulator body and terminal assembly is permanent and no radio interference can occur because of corona discharge caused from a loose terminal on the insulator body. Furthermore, no resilient sealing gasket is used and when making connections to or disconnecting other components of the terminal stud 48, excellent holding torque ?between the insulator body 12 and the terminal assembly 40 is obtaned because of the relatively large area of annular contact between the deformed lower skirt portion 44a and retaining surface 22. In addition, during the spinning operation, the side of the' skirt 44 is stretched somewhat and is deformed to closely conforn to the outer peripheral surface 20 of the end ridge 18 on the insulator body, and this also aids in holding the terminal firmly in place on the insulator body. The Belleville Washer 60 thus maintans a continuous biasng force and spacng between the end wall 42 of the terminal member and the end face 16 of the insulator body and prevents any loosening of the terminal because of relative expansion and contraction of the terminal and body.

In extremely hot weather, for example, if the metal terminal assembly 40 has a coefiicient of expansion greater than that of the insulator body 12, the end wall 42 will tend to move away from the end face 16. This relative movement does not result in a loosening of the terminal assembly on the insulator body, however, because the Belleville" Washer 60 is initially compressed during assembly and thereafter continuously exerts pressure between the two surfaces 16 and 42, thereby maintaining the deformed lower edge portion 44a of the skirt tightly against the retaining surface 22 on the end ridge 18. The result is a permanent and tightly maintained attachment of the terminal assembly 40 on the insulator body 12, providing for the above enumerated advantages over prior art insulators having resilient sealing gaskets.

The lower female terminal assembly 50 is generally similar to the upper terminal assembly and includes a cuplike metal terminal member having a circular end wall 52 and an annular skirt wall 54 extending upwardly therefrom. In order to provide for the drainage of any condensed moisture which may collect or accumulate within the recess 34 in the lower end of the insulator body 12, one or more weep holes 52a are provided in the end wall for drainage of water. Because the terminal assembly 50 is of the female type, a hollow, internally threaded, tubular sleeve 58 is provided, rather than a stud, and the sleeve extends upwardly into the recess 34 in the insulator body. The lower end of the sleeve extends downwardly through a central aperture or opening 56 in the end wall 52 and is permanently affixed to the end wall by welding, brazing, stackrg, or other suitable means. The lower terminal assembly 50 similarly includes a Belleville Washer 60 disposed 'between the upper surface of the end wall 52 and the lower end face 24 of the insulator body. The lower terminal assembly is assembled onto the lower end portion of the insulator body in the same manner as the upper terminal assembly 40, and the upper edge portion of the skirt wall 54 is deformed inwardly in a metal spining operation until it is in tight contact against the annular retaining surface 30 on the upper side of the integral ridge portion 28 at the lower end of the insulator body.

From the foregoing, it will be seen that the electrical insulator of the present invention provides many advantages and improvements over pror art insulators which employ resilient gaskets, or the like (subject to cold flow), between the terminal and the insulator body. No keyways, holes, threads, or recesses are required in the insulator body, making its Construction Simpler and less expensive. In addition, no external fastening means are needed for attaching the terminal to the insulator body. Loosening of the terminal on the body and resulting radio interference and connection and disconnection problems are eliminated, and failure of the terminal or insulator body because of relative expansion and contraction is eliminated.

What is' claimed as new and desired to be Secured by Letters Patent of the United States is:

1. An electrical insulator comprising a body of insulating material having a circular end face and a retanng surface spaced inwardly on said body from said end face, a terminal member of conducting material having an end wall facing the end face of said bodyand a skirt portion outwardly of said body extending between said end face and said retaining surface, said skirt including an outer edge portion deformed inwardly toward the center of said body and bea-ring against said retaining surface and annular, "Belleville Washer means disposed directly between and exerting pressure directly against said end face of said body and said end wall of said terminal means for holding said edge portion of said skirt tightly against said retaining surface, thereby preventing rotation of said terminal means on said body.

2. The insulator of claim 1 wherein the end face of said body comprises an annular surface around an inwardly extending axial recess formed in said body, connector means mounted on said terminal member defined by an internally threaded tubular member axially disposed in said recess through the center of said Belleville' Washer and Secured adjacent its outer end to said end wall of said terminal member.

3. The insulator of claim 1 wherein said Belleville' Washer has an outer edge portion in contact against said end wall of said terminal member.

References Cited UNITED STATES PATENTS 547,931 10/1895 Meaker 174-211 X 1,193,075 8/1916 Schmidt 29-511 X 1,797,418 3/ 1931 Hothersall 29-511 2,()14,44l 9/1935 Matthews 174--188 X 3,214,624 10/1965 Misare 174-188 X FOREIGN PATENTS l39,052 10/1934 Austria.

665,413 9/ 1938 Germany.

,249 9/ 1936 Switzerland.

l85,250 1/ 1937 Switzerland.

LARAMIE E. ASKIN, Prima ry Examiner U.S. CI. X.R. 2`9--511, 631

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