US 2432868 A
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Description (OCR text may contain errors)
Dec. 16, 1947. J. A. EARL Er AL.
METHOD oF REMovING INSULATION Filed April 4, 1944 WEA/Toes J A. Ene/ GTI.. KW7-r1.5 5V ,d-M7 l, @NORA/EY Patented Dec. 16, 1947 UNITED lSTATES PATENT v(')FFICE METHOD F REMOVING INSULATION Application April 4, 1944, Serial No. 529,554
This invention relates to a method of removing insulation.
In the manufacture of electrical apparatus, it quite frequently becomes desirable to remove insulation from the ends of metallic conductors, thus to facilitate their attachment to various portions of the electrical apparatus. Heretofore, numerous methods have been proposed, such as mechanically stripping the insulation from the end of the wire, or burning it therefrom. When insulation such as enamel is the material to be removed and where a plurality of strands of wire are to have insulation removed from them, the complete removal of the insulation mechanically requires a great deal of skill and care and takes an appreciable length of time to prevent damage to the conductors. In the method where an open flame was used to burn the insulation from the' burned from the conductor and, since the cavity,
is substantially enclosed, the oxygen in the cavity Will be burned and there will be little chance of oxidation of the conductor while it is in the cavity. Immediately upon removal of the conductor from the cavity and before the conductor has sufficient time to oxidize to an appreciable extent, it is quenched in a conveniently located bath of trichlorethylene, which will cool the conductor to the point where its oxidation will be apprecably slowed down and which will thus prevent undue oxidation of the conductor.
A complete understanding of the invention may be had'by reference to the following detailed description when considered in conjunction with the accompanying drawing, wherein the single gure discloses an apparatus constructed in accordance with thev invention and which may be used in the practicing of the method of the present invention.
In the drawing, the apparatus is shown mounted upon a base I, which serves to support a suitable container 2 containing a, supply of trichlorethylene and a standard 3. suitably mounted adjacent the upper end of the standard 3 is a lava tube 4 having suitably fixed to its inner surface a sheet of mica 5, which may be applied in any suitable manner to the inner surface of the tube 4. One end of the tubular structure thus formed is closed by a plug 6 formed of .Alundum cement. A tubular metal element l, having one end closed, as shown at 8 and in engagement with the plug 6, is positioned in the center of the lava tube 4. The tubular element I has a layer of electrical insulation 9, which may be mica, applied to it and around the cylinder thus formed by the tubular element 'I` and its outside layer of insulation a resistance wire Ill is wound, most of the resistance being provided at the open end of the element 'I to supply more heat to the open end of the chamben than is necessary at the closed end thereof. A huantity of asbestos packing II is placed between the sheet of mica 5 and the windings of resistance wire Ill to supplyheat insulation whereby the heat generated by the resistance wire I9 will be retained in the apparatus and will thus reduce the amount of current necessary to heat the tubular element 1. The resistance wire I0 may be connected by suitable leads (not shown) to a rheostat I2, which is, in turn, connected to any suitable current supply.
In practicing the method of .the present in vention, the temperature in the closed end of the tube is raised to approximately 1500 F. to burn substantially all of the oxygen on the inside of the tube when an insulated conductor is inserted therein and since the tube is open at one end, it comprises, in eiiect, a small non-oxidizing furnace, the interior of which may be heated to a temperature sufcient to burn the insulation I3 from a conductor I4 when the conductor is inserted in the tube and held there for a short time. The surfaces of the conductor I4 will, in the course of burning the insulation I3 therefrom, be heated to incandescence. However, there will be practically no oxidation of the surface of the conductor so long as it is held in the tubular element 1. As soon as the insulation I3 on that portion of the conductor extending into the tubular element 'I has been burned therefrom, the conductor may be withdrawn from the tubular element I and quickly plunged into the trichlorethylene in the container 2. In this manner, the conductor will be quenched without exposing it to the atmosphere for a sufficiently long time to permit an excessive amount of oxidation of its surface and, hence,'the conductor may readily be connected to other conducting parts of an electrical apparatus and will form a good conductive connection therewith.
What is claimed is:
1. A method of removing heat destructible insulation from a conductor which comprises producing ameless heat in a confined but accessible space of suiiiciently high temperature to destroy said insulation when said insulation is in said space, and inserting the end of an insulated conductor into said space to `effect the deoxidation of the space and the destruction of the insulation by the reaction of the insulation with the oxygen in said space thereby to remove the insulation.
2. A method of removing heat destructible insulation from a conductor which comprises producing flamesless heat in a confined but accessible space of sufficiently high temperature to destroy said insulation when said insulation is in said space, inserting the end of an insulated conductor into said space to effect the deoxidation of the space and the destruction of the insulation by the reaction of the insulation with the oxygen in said space thereby to remove the insulation, and transferring said end of the conductor directly from said space into a non-oxidizing quench.
3. A method of removing heat destructible insulation from a conductor which comprises pro- REFERENCES CITED The following references iile of this patent:
UNITED STATES PATENTS are of record in the 20 Number Name Date 1,882,947 Rotherham Oct. 18, 1932 2,116,228 Akin May 3, 1938 496,208 Procunier Apr. 25, 1893 1,035,596 Johnson Aug. 13, 1912 25 1,481,065 Opperman Jan. 15, 1924 2,116,228 Akin, Jr. May 3, 1938 1,595,793
Levinger Aug. 10, 1926