| 摘要 |
1479027 Curing polyolefin cable sheathing FUJIKURA CABLE WORKS Ltd 29 Aug 1974 [30 Aug 1973 30 Jan 1974 6 June 1974] 37800/74 Heading B5A An extruded cable sheathing comprising a polyolefin and cross linking agent, is extruded around the cable 1 from an extrusion die 5, to pass directly through a curing tube comprising upstream heating and downstream cooling zones 10, 16, through which silicone oil is circulated under a regulated pressure, and the sheathed cable exits from the curing tube through a die 20 provided with a means 19 which super-cools the silicone oil, e.g. to - 20‹ to - 40‹ C., to increase its viscosity and provide a seal between the die 20 and the sheathed cable 22. The silicone oil also acts to fill voids in the sheathing, and is cleared from the surface of the cable by a packing 21. The die 20 is exchangeably mounted. The embodiments relate to a bare cable core 1 to which is applied a semi-conductive inner sheath by a crosshead die 3, followed by insulating and semi-conductive sheathings applied by a crosshead die 5. In the Fig. 1 embodiment, the zones 10, 16, are separated by a seal packing 14 of foamed silicone rubber, and the silicone oil is separately circulated through each zone 10, and 16, by pumps 8, and 17, respectively delivering through a heater and through a cooling device 7, 18. The pressure is automatically regulated in each zone by a pump 23 delivering, via check and relief valves 11, 12 from a silicone oil tank 13 which is connected to a vacuum pump 24 to degass the oil. In the Fig. 2 embodiment (not shown) the packing 14 is replaced by a buffer zone comprising the silicone oil, e.g. along 0À5 to 1 m. length of the tube, cooled by water circulated through a cooling jacket (25) surrounding the tube. In this embodiment, the pressure from the pump (23) is applied only on the downstream side of the buffer zone, to the cooling zone. |
