US 2154551 A
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April .1 1939- H. v. WODTKE 2,154,551
v FLEXIBLE STRANDED CONDUCTOR Filed March 28, 1936 I mammal FIBROUJ mum Rwuinr .Srmos RUBBER 7 F6 19' I METALLIC 5mm:
' msuu'non lusuumou ummc 5mm INV ENT OR.
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0 quent bending or flexing.
Patented Apr. L8, 1939 v UNITED STATES PATENT OFFICE STRANDED CONDUCTOR Hans V. Wodtke, Marlon, Ind
or to Anaconda Wire & Cable Company, New York, N. Y., a corporation of Delaware My invention relates to stranded metallic conductors of electricity having a high degree of flexibility and more particularly to a stranded conductor in which all of the strands are twisted in a group in the same direction to form the finished conductor. Conductors oi the above type are commonly used with portable electric tools such as drills and grinders and lamps and are subject to he- In these cables, as heretofore constructed; each bending or fiexure tends to cause certain strands to bind against others. Moreover, the sliding incident to the flexing of the conductor causes friction and abrasion of one strand on an adjacent one.
My present invention provides a stranded conductor in which the binding of one strand on another and friction between the strands is avoided or largely eliminated.
The various features of the invention are iilustrated in connection with the accompanying drawing, in which l is a longitudinal view of a length of conductor cable embodying my invention, parts of the insulation being progressively cut away to show the construction; and Fig. 2 is a cross section of the cable shown in Fig. 1.
In my invention, I provide cushioning strands intermingled with the metallic strands of which the conductor is composed. These cushioning strands may be made of cotton or other textile or other material having suilicient impressibility and resilience so that any tendency to binding between the metallic strands will be ved by a compression or distortion of the ermingled resilient strands. In manufacshown in the accompanying drawing, the condoctors iii and l I covered by individual sheaths it it of insulating material, such asrubber,
are twisted together in helical turns. The spaces or valleys between the twisted conductors are then filled to an approximately circular cross .g the conductor, a number of cotton or other I section by means of a filling ll of suitable material, such as a fibrous or textile mass. The entire assembly is then enclosed in asheath l! of non-metallic material, such as rubber. It will be understood, howeventhat the conductors may be employed in various other cable constructions than that specifically shown in the drawper wires 66 and a number of strands ii, of resilient or fibrous material such as cotton thread. The threads I? may be of very low tensile strength, as they form merely a butler or number of buffers between the individual metallic strands l6. Shey may be incorporated most convenient- 1y by inter-mingling them with the metallic threads or wires, as the latter are being assembled and twisted so that in the twisting operation the threads will become and remain. scattered throughout the strand. It will be understood that the position of any particular thread may vary at different intervals in the length of the conductor and may at'successive intervals occupy any position from the center to the outer periphery oi the conductor..
several threads or strands of resilient material act as buffers, that when any two er more strands tend to crowd together when on the inside or outside of a turn the necessary space to prevent binding is made by a compressicn of the fibrous material. The sharpness of 1 the bending for any particular wire of the strand is generally lessened by relieving the binding of the wires.
Bering the bending or flexing of the conduc tor, displacement of the individual metallic wires is liable to take place. Such displacement either longitudinal or crosswise tends to rub the sur face of one wire against the surface of an Jacent wire. The interposition of the resilient strands, however, tends to lessen the direct contact of one wire on another and the consequent direct rubbing of the wires. The relative movement of the strands may take place on opposite sides of a resilient thread and the friction largely avoided. This friction may be still furtherlessened by impregnating the resilient strands with lubricating oils or solid such as graphite. These materials also tend to form a preservative coating on the wires protecting them against corrosion, particularly in those cases in which an impervious protective outer Jacket is not used.
What I claim is:
1. A stranded eiectrical conductor for flexible cords comprising a plurality of metallic conducting strands twisted into a common with strands of said assembly in conductive contact with other strands and strands oi resilient material irregularly interspersed and twisted with said metallic strands in said conductor to vary in cross sectional position in the conductor and in relation to other strands at successive longitudinal distances. I
2. The conductor of claim 1, in which said strands of resilient material are of fibrous textile materim.
3. 'meconductcrotclalmLinwhichsaidresilient strands are oi cotton.
4. The conductorot claim Linwhichsaidrcsilient strands are oi. relatively low tensile strength.
5. The conductor of claim 1, in which said nesilient strands carry a lubricant.
6. The conductor of claim 1, in which said strands are impregnated. with an oil.
HANS V. WODTKE.