Patent GB-449625-A (GB)
Title: Improvements in or relating to methods of and apparatus for the manufacture of conduit for carrying conductors for use in electrical circuits
IPC: B29C48/156
Filed: 1935-01-11
Abstract: 449,625. Conduits. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburgh, Pennsylvania, U.S.A.-(Assignees of Abbott, C. W.; 5, Acorn Lane, Larchmont, New York, U.S.A.) Jan. 11, 1935, No. 1009. Convention date, July 14, 1934. [Class 36] [See also Group V] An electric conduit is formed by extruding rubber or other plastic dielectric material from a die which so shapes the material that, after. subsequent curing and processing, it forms two or more conductorreceiving channels each having a deformable closure wall through which the conductor may be introduced. Fig. 22 shows a conduit comprising a rubber body 107 having a base portion 53, vertical walls 55, 54, 60, 56 and horizontal walls 57, 58 which co-operate to form channels 51, 52 for receiving bare or lightly insulated conductors 41, 42. The walls 57, 54 and 58, 60 are initially joined together and are subsequently slit apart to permit of insertion of the conductors 41, 42 into the channels 51, 52, the joint being restored by a rubber-coated tape 59 which is secured to the top of the conduit. The walls 54, 60 are separated by a narrow V-shaped slot 61 at the bottom of which is disposed an auxiliary conductor 250. A tape 90 is secured to the lower face of the conduit. The body 107 is formed by extruding rubber compound through a die 73, Fig. 3, of an extrusion machine 70, the body being extruded on, and carried forward by, the tape 90 which passes from a drum 81 to the lower edge of the die 73 and thence to a take-off drum 92 around which the tape and the extruded body are coiled one or more times before passing to a drum 100 which is adapted to receive, in a single layer, a manufacturing length of the conduit. The extruded body wound on the drum 100 is then vulcanized and the drum transferred to supports 115, Fig. 10, so that the vulcanized body 107 may be fed from the drum along a guideway 116. In passing along the guideway the body 107 is operated on by a buffing wheel 118 adapted to provide a surface on the upper face of the body suitable for receiving the tape 59, Fig. 22 ; knives 120, 121, Figs. 10 and 12, adapted to slit the upper walls of the conductor channels ; devices 122, 123, Fig. 10, for opening the slits, dusting the conductor channels with powdered soapstone and feeding conductors 41, 42 from reels 130, 131 into the opened conductor channels. The conduit thus formed is taken round a capstan 140 and passed to another section of the guideway 116, Fig. 14, on which the tape 59 is applied to the upper surface of the body 107. For this purpose a layer of latex or other adhesive material is applied to the upper surface of the body by a device 150 and, after partial setting of the latex layer by passage of the body 107 through a drying chamber 155, the tape 59, coated with latex by passage through a latex bath 163, is pressed on the latex layer by a wheel 166. The conduit then passes through a drying chamber 167 in which the latex is fully set and thence to apparatus for spraying a finish of lacquer on the sides and top of the conduit. The die 73, Figs. 3 and 6, for shaping the body 107 are adapted to form a body similar in shape to the finished conduit but with the two halves of the body tilted on either side of the vertical, as shown in Fig. 6, so that a V-shaped channel 61 is formed between the central walls of the body into which an auxiliary conductor 250, Fig. 22, may be laid. To prevent adhesion between the central walls 54, 60, the extruded body leaving the die 73 passes through a device 91 which applies powdered soapstone to the channel 61. The auxiliary conductor 250 may be fed from a drum 25, Fig. 3, through the worm of the extrusion machine 70 and through a hole in the die 73 into the channel 61 ; or the auxiliary conductor may be introduced into the channel 61 at the same time as the conductors 41, 42 are inserted into the conductor channels. The tape 90, Fig. 3, may pass through a slot in the die 73 so as to form the lower edge of the extrusion orifice. In a modified construction the die of the extrusion machine is so shaped as to produce a conduit body 30, Fig. 1, having open conductor-receiving channels 31, 32, which, after the insertion of the conductors 41, 42, are closed by flaps 37, 38 formed integrally with the side walls 35, 36 of the conductorreceiving channels. Specification 448,037 is referred to.