Patent GB-1375016-A (GB)
IPC: B29C48/09
Filed: 1971-11-02
Abstract: 1375016 Helically reinforced extruded tube DAYCO CORP 2 Nov 1971 [13 Nov 1970] 50878/71 Heading B5A [Also in Divisions F2 and B3] A reinforced tube is continuously formed by delivering a wire W, Fig. 3, through a device which forms it into a helical coil S which is delivered, without rotation about its axis, to an extruder head 60 through which it is also delivered without rotation by an internally engaging helical screw thread 90, Fig. 6, to be incorporated as the reinforcement within a tubular plastics or rubber sheath, extruded from a surrounding tubular extrusion outlet 88 and which is drawn by a vacuum into contact with, and into corrugated form between, the coils of the wire S. The vacuum is applied via passages 108, 110, 112. The tube is delivered from the extruder through a device where cooling is effected by a water filled trough or water nozzles, and drying by hot air nozzles. The screw 90 is supported within a bore 80 of the extrusion head 60 by press fitted bearings 94, 96, the outer race of the latter being axially adjusted by a member 99 to eliminate play, and rotation of the screw 90 is effected by a pulley 103 press-fitted thereto. The extrusion outlet 88 is defined between a radially adjustable die 85, and an inner sleeve 81 through which the bore 80 extends, and extrudate is supplied to the outlet 88 via head inlet 67 and a frusto-conical passage 78. The tube may be wound into a roll, or cut into lengths, but is preferably delivered, Fig. 7, not shown, through a braiding or knitting machine which applies a tubular fabric to the extruded tubular sheath and to which is applied a further extruded sheath (similarly under vacuum) upon following passage through a further extruder and cooling device, to which and from which it is delivered by endless belt devices. The extruded tubular sheaths, and a pre-coating which may be applied to the wire W, may comprise a vinyl polymer, a polyolefine or a natural or synthetic rubber. The wire W may comprise two or three insulated electrical wires formed into two or three co-extensive helical coils by the device and fed through the extrusion head 60 by a two or three start screw 90, and such a tube may be employed in a vacuum sweeper for transmitting power to a portable suction head incorporating a motor driven beater. Longitudinally extending wires or cords may also be incorporated during extrusion into the tube between the extruded sheath and either the coil S or the tubular fabric. The device for forming the coil S comprises a base 20 having a tubular inlet 21 and a tubular outlet 23 respectively for the uncoiled W and coiled wire S. Coiling is effected by delivery of the wire W within peripheral grooves of a freely rotatable roller set 52, 53 effected by a wheel 30 rotated about shaft 33 by bevel gearing 38, 39 and a drive pulley 42, and around which wheel 30 the wire W is wrapped within a wheel groove 31 into which the wire W is urged by resiliently surfaced rollers (48), Fig. 1 (not shown) located around the wheel periphery. Rotation of the coil S about its axis is avoided during formation forming of the coils by rotation of the device about the axis of the inlet and outlet 21, 23, effected by drive pulley 27 and within bearings 22, 24. The pulleys 27, 42, and 103 are each driven by a separate motor, the speeds of which are independently variable from a controller to ensure the necessary non-rotative delivery of the coil S.