GB665418A - Improvements in the manufacture of insulated electric conductors - Google Patents

Abstract

665,418. Making electric conductors. BRITISH INSULATED CALLENDER'S CABLES, Ltd., KEEFE, E. J., and LORCH, H. R. Oct. 13, 1950 [Oct. 14, 1949], No. 26389/49. Classes 83 (ii) and 83 (iv). [Also in Group XXXVI] Drawing; soldering.-An electric conductor of the type comprising one or more wires enclosed in a tubular metal envelope and embedded in a body of compacted insulating powder is manufactured by a continuous process in which an envelope of substantially uniform thickness is formed around the wires and insulating powder by bending a thin strip of ductile metal transversely to produce two or more complete turns while the wires move continuously forward, accurately shaping the envelope by passing it through a die, securing the overlapping edges by soldering, and drawing the envelope through a reducing die to compress the powder. The. powder, which is preferably talc, may be extruded around the wires in the form of a paste which is dried prior to the formation of the envelope, or it may be fed in the dry state into the space between the wires and the envelope during the formation of the latter. In the former method the paste 1 (Fig. 1), is extruded on to the wire 2 from a press 3, the covered wire then passing through an oven 8 in which the covering 7 is dried. The covered wire then passes through ,a die 9, 10, the two parts of which form an annular conical space into which a metal strip 11 is fed. This strip. is preferably of solder-coated copper, and is folded in the die, emerging at 13 having the shape shown in Fig. 2 E-E. The sheathed wire then passes through a soldering die 15 which is heated to cause the solder to flow and impart a smooth finish to the metal sheath (Fig. 2 F-F). In the second method the press 3 and oven 8 are omitted, the dry insulating powder being fed to the inner cone of the folding die within which is a coaxial hollow feed screw through which the conductor passes. The sheathed wire then passes through a soldering die as before. In both processes the covered wire is finally passed through a reducing die to compress the powder within the envelope.