Apparatus for manufacturing coaxial cable

摘要

In the dual extrusion manufacture of an insulated coaxial cable having one or more spiral spacing ribs 2a wrapped around an inner conductor 1 and surrounded by a tubular sheath 2b, the longitudinal contraction of the sheath during cooling and the attendant warp curvature of the rib is avoided by providing a sizing device 7 having a central die portion 12 with vacuum exhaust holes 14 therein. Water from a cooling pool 8 is drawn in through the clearance space between the sheath and the die portion as the cable passes therethrough to pre-cool and lubricate it, and one or more dies 15 are provided in the cooling pool to prevent the longitudinal contraction of the sheath and thereby avoid any appreciable rib inclination or curvature.