Electricity: conductors and insulators – Insulators – With insulator-supporting or attaching means
Reexamination Certificate
1999-12-01
2001-12-04
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Insulators
With insulator-supporting or attaching means
C174S16300R, C174S154000, C174S188000
Reexamination Certificate
active
06326552
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to insulators and, more particularly, is concerned with an insulator end fitting with a non-machined annular attachment flange.
2. Description of the Prior Art
Insulators are widely used by the electric utility industry for a variety of applications. Heretofore, Ohio Brass, a subsidiary of Hubbell Incorporated, has manufactured and marketed a number of different types of insulators, sometimes referred to as polymer insulators, for different applications, such as deadend, suspension, transmission, line post and the like.
Referring to
FIGS. 1
to
12
, there is illustrated a typical prior art insulator
10
. The insulator
10
basically includes an elongated fiberglass rod
12
, a plurality of weathersheds
14
disposed end-to-end along the rod
12
and an end fitting
16
attached on each of a pair of opposite ends
12
A of the fiberglass rod
12
. The weathersheds
14
are typically made of rubber and are either molded directly around the rod
12
or slipped thereover with the use of a dielectric grease as a rubber-rod interface. The end fittings
16
are typically of various shapes, as seen in
FIGS. 2
to
6
, to serve a variety of utility applications and are normally made of ductile iron and fabricated by casting and either potted (glued) or crimped onto the ends of the fiberglass rod. Whether potted or crimped to the fiberglass rod, a hole
18
is first bored in one end
16
A of a solid cast body of the end fitting
16
to receive one of the ends
12
A of the rod
12
.
Where a crimp attachment is to be used the end fitting fabrication steps typically employed are as follows. First, a cast of the solid body of the end fitting is made, such as in a sand cast mold. Next, a first machining operation is performed on the end fitting to provide a precise known outside diameter on the one end of the end fitting to use later in boring the hole. Following next, the whole end fitting is hot dip galvanized. Then, a second machining operation is performed on the end fitting by boring the hole in the end thereof to accept the end of the fiberglass rod. By employment of the two machining operations, the flange portion left on the end fitting about the hole has the desired thickness appropriate for the crimping operation. Ductile iron is usually used for the cast portion of the end fittings and, if ductile iron is used, then low carbon steel is used for the annular attachment flange. However, cast aluminum could be used for an end fitting and then the annular attachment flange would also be aluminum.
The above-described fabrication steps, though effective in producing an end fitting having a suitable end flange portion adapted to receive an end of the fiberglass rod, are nonetheless costly and time-consuming to carry out Consequently, there is a need for innovation in the method of fabricating the end fitting that will overcome these problems without introducing new problems in place thereof.
SUMMARY OF THE INVENTION
The present invention provides an insulator end fitting designed to satisfy the aforementioned need. The end fitting of the present invention involves casting the body of the end fitting with a non-machined annular attachment flange that utilizes a preformed annular member. This provides a more cost-effective and less complicated way of fabricating the end fitting by eliminating the need for the two secondary machining operations and their associated high costs of the prior art method of fabricating the attachment flange portion of the end fitting to prepare the end fitting for receiving and crimping on a fiberglass rod of the insulator.
Accordingly, the present invention is directed to an end fitting for an insulator which comprises: (a) a main cast body for securement to an external structure; and (b) a non-machined annular flange rigidly attached at an end of the main cast body and defining a hole for receiving an end of a fiberglass rod to secure the annular flange to the fiberglass rod in assembling the insulator. At least a portion of the annular flange is comprised of a preformed annular member defining at least an interior diameter of the annular flange.
More particularly, the preformed annular member can take any one of three different embodiments. In a first embodiment, the preformed annular member is a section of pipe. The end of the main cast body has an annular recess receiving an end of the section of pipe such that the main cast body is rigidly attached to the end of the section of pipe. In a second embodiment, the preformed annular member is a precut metal tube disposed at interior diameter of the annular flange. The annular flange includes an annular cast body surrounding the precut metal tube and integrally attached to the main cast body at the end thereof and made of the same material as the main cast body. In a third embodiment, the preformed annular member is a prestamped metal tubular member having interior and exterior annular walls disposed at the interior and exterior diameters of the annular flange. The annular flange includes an annular cast body disposed between the interior and exterior annular walls of the prestamped metal tubular member and integrally attached to the main cast body at the end thereof and made of the same material as the main cast body.
The present invention is also directed to an insulator which comprises: (a) an elongated fiberglass rod having a pair of opposite ends; (b) a plurality of weathersheds disposed along the fiberglass rod between the opposite ends thereof; and (c) a pair of end fittings each crimped to one of the opposite ends of the fiberglass rod, each of the end fittings having the construction as described above.
These and other features and advantages of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
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Kester Jeffrey J.
Krause John A.
Hubbel Incorporated
Reichard Dean A.
Swartz Michael R.
Walkenhorst W. David
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