| 摘要 |
538,827. Coating cables by extrusion. TELEGRAPH CONSTRUCTION & MAINTENANCE CO., Ltd., DEAN, J. N., and WEBSTER, J. Nov. 13, 1939, No. 30004. [Class 87 (ii)] [Also in Group XXXVI] Thermoplastic insulation is treated in the plastic condition in vacuo on its way to, and while being applied to, the conductor, so as to remove voids and occluded gases. Figs. 1 and 6 show alternative means for treating the insulation and Fig. 7 shows a means for leading the conductor to the point where the insulation is extruded thereon from the means shown in Fig. 1 or 6. The screw-type forcing machine A is connected by a pipe B to a heated die B' which is flared in the direction normal to the plane of the drawing so as to produce a ribbon C of plastic material which is passed by feed rolls E in a vacuum chamber D through the pipe G to another extrusion machine F, which is shown as a gear pump mechanism but may be similar to A. The solid material passes to a heated die H and through ports J whence it passes to the die proper for application to the conductor. In Fig. 6 vacuum chambers D, D and rolls I, L, M are provided for passing the material to a screw extrusion device O, boats P being provided in both Figs. to seal the passage of the material from the rolls. In Fig. 7, the material is fed through orifices 2 to the die 1 which is connected with the die H or O of Fig. 1 or 6. The conductor passes through one or more sets of dies 13 screwed to plates 12 which in turn are screwed to walls of high-vacuum chambers 7, 8, which, as also the parts A, B, F of Fig. 1, may be either steam or oil-jacketed or electrically heated. The material may be gutta percha, synthetic resins, or the preparations described in Specifications 322,208, [Class 70], 346,382 and 373,134.
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