GB1292609A - Improvements in or relating to methods of making insulated tinsel conductors and cords - Google Patents

Abstract

1292609 Flexible insulated conductor WESTERN ELECTRIC CO Inc 10 Dec 1969 [27 Dec 1968] 60267/69 Heading H1A A conductor 2, Fig. 2 (not shown), comprises tinsel ribbons wound on a cotton strand or polymer monofilament, the winding being in the form of single or double lay helices with butting or overlapping edges, or more than one helix per lay, a typical ribbon being À020 inches wide and À001 inches thick. A polymer tube 8 is extruded on to the conductor 2, by a tubing mill 5, with a clearance between the conductor and the tube, and after passing through cooler 9, the insulated conductor passes through a heat chamber 13 where it is heated to about 320‹ F., followed by a cooling trough 14 which cools the insulated conductor to 100‹ F. Capstan 12 is driven faster than capstan 10, so that the insulated conductor is stretched by up to 10%, preferably from 4 to 5%, causing the tube 8 to become stress oriented, increasing its tensile modulus and reducing the clearance to À001 inches. It is stated that such a treatment makes it possible for the polymer to recover an original helical set after extensions up to several times its original length. The insulator material may be a polyamide, polypropylene or polyethylene. The chamber 13 may be heated by gas, superheated steam, or an inductive heating coil. An outer jacket (16), Fig. 2, (not shown), may be applied over a number of the above conductors, and by winding such a cord on a mandrel, heating it to about 320‹ F. for about 9 minutes to heat set it, and subsequently reversing the direction of the helix a retractile cord may be made, see Fig. 3 (not shown).