| 摘要 |
1,150,517. Coating cores by extrusion. PHELPS DODGE COPPER PRODUCTS CORP. 22 Sept., 1967 [28 Sept., 1966], No. 43343/67. Heading B5A. [Also in Division H1] A core 10, e.g. an electrical conductor, is provided with a helical web 12 of thermoplastic or thermosetting resin, by extrusion of the resin through a rotating die 38 via a passageway 42 which extends radially from a bore 40 to a position within the periphery of the die, see also Fig. 4 (not reproduced). Bore 40 accommodates core 10 and may be of such a diameter that a sheath of resin is formed on the core in addition to the web. Die 38 is mounted for rotation with a carrier 44 by means of a key 45 and the carrier is rotated by a variable speed electric motor 53 via gearing 50, 54. The pitch of helical web 12 may be varied by changing the ratio of the speed of operation of core transport mechanism (26), Fig. 2 (not shown), and the speed of rotation of die 38. A speed control (30) co-ordinates the speed of operation of the core transport mechanism and the feed of resin to the die, e.g. by change of speed of feed screw 36, so that the web remains of uniform thickness. The various speed changes may be effected automatically. Specific thermoplastic resins mentioned are polyethylene and polysulfone and a cooling apparatus (24), Fig. 2 (not shown), may be provided.
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