Electricity: conductors and insulators – Insulators – With terminal elements
Reexamination Certificate
1998-11-16
2001-05-08
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Insulators
With terminal elements
C174S209000
Reexamination Certificate
active
06229094
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an insulator having a torque-resistant or torque-prevailing crimped insulator end fitting. More particularly, the invention is also directed to a method of crimping an insulator end fitting so as to be resistant to torque tending to loosen mounting bolt connections of the insulator.
The utilization of rubber-covered insulators possessing fiberglass cores, and which incorporate metal end fittings, is widely known and employed in connection with an extensive variety of both overhead and underground electrical power transmission devices. For instance, one such device employing an insulator comprises a pad mount switch gear wherein the insulator is utilized as a support mechanism for hardware which is at line potential, with such insulators being frequently in the configuration of so-called post insulators, as is known in the technology.
Ordinarily, in order to mount the insulator to the hardware, arranged at each end of the post insulator are between two or four bolts which are engage able into tapped or threaded bolt holes. Suitable lock washers are arranged on the bolts in order to eliminate any bolt rotation or loosening subsequent to the application of the appropriate necessary tightening torque to the connector bolts of the end fitting.
The prevention of any bolt loosening is imperative, inasmuch as any loose bolts can readily result in the insulator performing improperly, and could also be conceivably the cause of radio noise or static. In essence, an important problem facing the industry in connection with the foregoing resides in the prevention of any loosening of the connections of the end fittings, and resultingly, the attachment of the insulators to the devices where the insulators are employed as support mechanisms.
2. Discussion of the Prior Art
Presently, various types of end fittings for piping or similar uses are known and widely employed in industry and commerce.
Whittle, et al., U.S. Pat. No. 5,228,721 discloses a pipe fitting wherein a pipe end is adapted to be inserted into a suitable end fitting. The fitting has a tubular section insertable into the pipe end, and has a plurality of axially spaced, radially outwardly extending circumferential ribs. The pipe fitting, with the end of the pipe extending thereover, has the pipe end encompassed by an annular sleeve. A crimping ring is mounted on the sleeve and then crimped inwardly so as to cause the ribs to bite into and grippingly engage the inner circumferential wall surface of the pipe end, thereby locking all of the elements together. This is basically a standard type of crimping arrangement for various types of piping or the like, necessitating numerous components which are not particularly suitable for post insulators.
Anderson, U.S. Pat. Nos. 5,364,134 and 5,364,135 each disclose an end fitting for flexible conduits, wherein a crimping ring is adapted to be positioned about an axially a projecting portion of the end fitting so as to be insertable into the essentially cylindrical conduit. Thereafter, the crimping ring is crimped radially inwardly so as to provide a gripping and axially locked contact with the conduit and the end fitting.
Hayward, U.S. Pat. No. 4,797,121 discloses a “tee” fitting for tapping into a coaxial cable network, wherein crimping sleeves or rings are slid over an external insulation segment of the conduits and then crimped so as to produce a gripping or clamping engagement with the insulation and the fitting.
Although the foregoing publications disclose various types of crimping rings, none of these are applicable to providing the torque-resistant fastening of piping or conduits to end fittings for insulators of the type described herein, inasmuch as the various prior art crimping rings are not torque-prevailing or torque-resistant, and in effect, permit for rotational movement between the various fitting components while concurrently possessing only a limited degree of strength against the effects of axial tensile forces.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides for post insulator structures which may be constituted of rubber and contain rubber-coated fiberglass cores, and possessing metallic end fittings at opposite ends of the post insulator. The essentially elongate tubular insulator may be equipped with a series of circumferential disk elements or fins forming weather sheds which are spaced along the length of the insulator, and with the metal end fittings being fastened to opposite ends of the post-shaped tubular insulator, the latter of which is adapted to receive the cylindrical fiberglass cores.
To facilitate the secure attaching of the insulator to various electrical power devices; for instance, such as pad mount switch gears or the like, wherein the insulator is basically employed as a support mechanism for hardware at line potential, the insulator is equipped with metallic end fittings at each end thereof. The fittings are each constituted of an essentially hollow cylindrical sleeve-like element having bosses spaced thereabout. The bosses are basically circular protrusions each tapped to provide bolt holes extending in parallel to the center axis of the fitting to a particular depth so as to form either blind or through-extending screwthreaded bores.
In order to provide for the fastening together of the various components comprising the post insulator, the fiberglass core located therein and which protrudes from the opposite ends of the insulator and has the end fittings seated thereon in close interference engagement, by mounting the insulator through the intermediary of the end fittings being attached to power devices by threaded bolts extending from the devices being engaged in the tapped bolt holes, and whereby radially inwardly directed crimping forces are applied to the cylindrical wall structure of the end fittings intermediate the locations of the bosses having the bolts tightened within the threaded bolt holes. The radial crimping forces intermediate the bolt hole locations produce a deformation of the bolt holes, in effect, the fitting material is crimped such that the tapped bolt holes in the bosses deviate or distort from their original round configurations in that the material is pushed radially inwardly to cause the bolt holes to assume a somewhat out-of-round or ovoid configuration. This crimping action causes the screwthreads of the tapped bolt holes to deform during crimping, creating a locking engagement with the screwthreads of the therein inserted bolts, and preventing the bolts from loosening by being rotated out of the bolt holes. This, in essence, provides the bolt locking action which eliminates the need for the provision of lock washers or other fastening elements.
Accordingly, it is an object of the present invention to provide an insulator of the post type as described herein, including end fittings for connection with power ground transmission devices, wherein connector bolts are locked into tapped bores in bosses on the end fittings of the insulator through the application of crimping forces to the end fittings.
Another object of the present invention resides in the provision of a method for securing a post insulator to hardware through the intermediary of crimping action tending to deform threaded bolt holes tapped in end fittings of the insulator, thereby locking connector bolts therein secured against loosening rotation so as to ensure appropriate latching of components upon the assembling of the insulator to power devices.
REFERENCES:
patent: 4797121 (1989-01-01), Hayward
patent: 5228721 (1993-07-01), Whittle et al.
patent: 5336852 (1994-08-01), Goch et al.
patent: 5364134 (1994-11-01), Anderson
patent: 5364135 (1994-11-01), Anderson
patent: 5977487 (1999-11-01), Kuhl
'Hubbell Incorporated
Nino Adolfo
Presser Leopold
Presson Jerry M.
Reichard Dean A.
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