GB1167551A - Heaters and Methods of Making Same - Google Patents

Abstract

1,167,551. Coating cores by extrusion. TEXAS INSTRUMENTS Inc. 2 Nov., 1966 [1 Dec., 1965], No. 49155/66. Heading B5A. [Also in Divisions F2, H1 and H5] A tubular resistance heater 11 is made by moving a tube 12 of polytetrafluoroethylene or polyethylene into an extrusion head 14 at a speed of 25 ft./min., extruding at 450‹ F. a sleeve 16 of carbon black filled cross-linked polyethylene, helically winding about the tube two strips 24, 26 of perforated copper foil or wire mesh which are pressed into the sleeve 16 by pairs of rollers 28, 29, and 30, 31, heated to 250‹ F., and then passing the assembly through an extrusion head 32 to extrude a polyethylene sleeve 20 at 350‹ F. about strips 24, 26, and sleeve 16. A flat resistance heater is made by extruding a web 42 of resistance material from an extrusion head 40 at 350‹ F. and travelling at 25 ft./min., feeding perforated strip 50, 52, between die members 54 and web 42 to bend the strip into clamping engagement with the edges of web 42, passing the assembly through rollers 55, 56, 57, 58 at 300‹ F., and then passing through extrusion head 60 at 300‹ F. to extrude an outer polythene jacket 62. A further heater comprises a web 70 of resistance material preheated to 300-500‹ F., perforated strip 80, 82, pressed into the web by heated rollers 73, 74, which reduce the heater thickness, and an outer extruded jacket 86.