Patent GB-651623-A (GB)
Title: Improvements relating to the covering of electric conductors and cable cores with rubber or similar material
IPC: B29C48/00
Filed: 1948-10-11
Abstract: 651,623. Cable-making machines. BRITISH INSULATED CALLENDER'S CABLES, Ltd., RICHARDSON, A. B. F. G., TUNNICLIFF, E., and FISHER, I. K. Oct. 11, 1948, No. 26480. [Class 36] [Also in Group V] A continuous process'comprises the following steps :- (a) a covering of rubber or similar material is extruded on to the core &c. whilst the core is travelling at a constant linear speed; (b) the hot covering is cooled by contact with a fluid coolant; (c) the cooled covered core is passed into and through a vulcanizing chamber containing hot fluid under pressure; (d) the core with its vulcanized covering is passed, directly and without material change in the external pressure exerted upon it, into and through a cooling liquid maintained under a pressure substantially equal to that of the vulcanizing fluid; (e) finally the core with the cooled vulcanized rubber covering is reeled. A core 1 is drawn off a reel 2 by a capstan 3 and passed into a screw extruder 4 where a rubber covering is applied. The core may be subjected to vacuum before covering, by fitting a vacuum seal 39 to the core tube 40 or to an extension thereof and evacuating the tube. The core tube may be water-cooled. The covered core then passes through a long open trough 8 which is kept filled with cold water, over guide pulley 10, around capstan 9, over pulleys 13a, 13b, 14a and 14b, and through an inlet sealing gland 22 into a vulcanizing chamber 15. This gland 22 may be of the kind described in Specification 651,622, [Group XXVI], in which escape of steam from the vulcanizing chamber is prevented or reduced by water under pressure or other counter-pressure fluid, water escaping from the gland being collected in a catch box 23. Steam &c. is passed into the vulcanizing chamber 15 through an inlet pipe 18 and distributer sleeve 17, and condensate is removed through outlet pipe 24. The chamber 15 is surrounded by a jacket 16 which is fed with steam &c. at 19 and relieved of condensate at 25. The outlet end of the tube 15 is shown in Fig. 3 and includes the same fittings as those shown at the inlet end in Fig. 2. From the vulcanizing chamber 15 the covered core passes through an outlet gland 26 into a cooling tube 27 into which cooling water &c., at the same pressure as that of the steam in chamber 15, is fed by a pipe 29. The gland 26 may be of the kind described in Specification 651,634, [Group XXVI], in which escape of steam from the vulcanizing tube is prevented by rubber or other bushes which are pressed towards the covered core by pressure water from pipe 28. The covered core emerges from the cooling tube through a gland 30 similar to gland 26 but not fed with pressure water so that water from the cooling tube escapes therethrough. The cooled core passes around a capstan 35 and on to a reel 36. The three capstans 3, 9, 35 are driven by an electric motor 37. The peripheral speed of capstan 9 is slightly less than those of capstans 3 and 35. All three capstans may rotate at the same angular velocity, the variation in peripheral speed being obtained by making the surfaces of two of them, preferably 3 and 35, of stepped form, and making them axially slidable. The capstan 9 may be omitted.