Tools – Wire stripper
Reexamination Certificate
1998-10-22
2001-09-25
Smith, James G. (Department: 3723)
Tools
Wire stripper
Reexamination Certificate
active
06293171
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to a wire stripper and, more specifically, to a wire stripper, which may be referred to as a FARENSTRIPPER™, for thermocouple cable.
BACKGROUND OF THE INVENTION
In the specialized field of thermocouple manufacture, the stripping of insulation from 30/36 gauge (0.010″/0.005″ diameter) wire presents a significant problem. In one embodiment, a thermocouple is formed from two dissimilar metal wires manufactured with a very thin insulation of TEFLON®, about each individual wire, with an additional insulation wrap about both wires.
To form the thermocouple, one who is skilled in the art must strip a length of insulation from both wires, then twist the bare wires and weld them. Because the wires are extremely delicate, they are easily damaged. A sharp edge on the stripping tool may cause a nick in the wire that will result in premature failure of the thermocouple.
Conventional, all-purpose, wire strippers, such as used by commercial electricians, are much too rugged for the delicate wires of a thermocouple. “No-nick”, plier-like, stripping tools are available, but the precision available for stripping thermocouple cable is only useable on a single wire, necessitating splitting the outer insulation so that each wire may be stripped individually a tedious and time intensive process to remove three pieces of insulation.
It is also possible to use heat from a flame to burn the insulation away. However, this is very imprecise and somewhat dangerous. A specialized thermal wire stripper is available, but the retail price is in excess of $200—not very cost effective and not portable. One last resort for this process is to pinch the insulation between a finger and the thumbnail, and to pull the insulation off of the wires after removing the outer layer and splitting the conductor pair. Unfortunately, this method becomes difficult, time consuming, and the fingernail eventually wears from repeated usage.
Accordingly, what is needed in the art is an inexpensive wire stripping apparatus that reliably and simultaneously removes the insulation from both wires of duplex thermocouple cable without damaging the wire and to eliminate the need for replacement cutting blades.
SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides an apparatus for, and method of, stripping insulation from an electrical wire. In one embodiment, the apparatus includes: (1) a stripping member having a curved (perhaps cylindrical or conical), irregular surface thereon that is frictionally engageable with the insulation to apply a stripping force thereto and (2) a handle, coupled to (connected to or surrounding) an end of the stripping member, that allows a stripping force to be applied to the stripping member.
The present invention therefore introduces a simple, portable, perhaps one-piece tool, with no moving parts being necessary, for removing the insulation from a wire. For purposes of the present invention, “irregular surface” is defined as a surface (1) having bumps or indentations (perhaps knurls) of such number, height and/or depth that frictional engagement with insulation is sufficient to support a stripping force and (2) lacking sharp surface discontinuities that would tend to nick a wire while stripping it.
In one embodiment of the present invention, a radius of curvature of the surface is less than about 0.0625 inch. This translates to an overall diameter for the stripping member of about 0.125 inch. Of course, the present invention is not restricted to such a range in its broadest form. Further, the optimal curvature for the surface is related to the gauge and strand count of the wire being stripped.
In one embodiment of the present invention, the wire has two layers of insulation, the surface frictionally engageable with both of the two layers to apply the stripping force thereto. In an embodiment to be illustrated and described, the wire to be stripped is a thermocouple cable having first and second wires surrounded by first and second inner insulation and outer insulation.
In one embodiment of the present invention, the stripping member is composed of a material selected from the group consisting of: (1) metal (perhaps powdered), (2) ceramic and (3) plastic. Those skilled in the art will recognize the materials that have the appropriate physical attributes to act as a stripping member. The present invention contemplates all such materials.
In one embodiment of the present invention, the handle is separable from the stripping member. Alternatively, the handle may be integrally formed with the stripping member as a single piece.
In one embodiment of the present invention, the stripping member is laterally moveable with respect to the insulation to apply the stripping force (usually in the direction of the end to be welded). In the embodiment to be illustrated and described, the apparatus is held laterally (perhaps about 90°) with respect to the wire to be stripped and moved generally along the axis of the wire.
In one embodiment of the present invention, the stripping member urges the insulation against a compliant surface to apply the stripping force. The compliant surface may be a human digit or any other suitable surface for holding the insulation against the stripping member.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same (perhaps automated) purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
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Avaya Technology Corp.
Shakeri Hadi
Smith James G.
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