GB855364A - Flexible conduits - Google Patents

Abstract

855,364. Flexible conduits. DAYCO CORPORATION, [formerly DAYTON RUBBER CO.]. Oct. 31, 1958 [Nov. 25, 1957], No. 35054/58. Class 99(2). In a flexible, fluid-impervious conduit, a helical coil of plastic or rubber coated wire 12 is surrounded and elastically embraced by a first elastomeric sheath 14 which is itself surrounded by a second coextensive elastomeric sheath 15 in partial elastically embracing contact with the sheath 14 and otherwise closely spaced therefrom. As shown, the sheath 14 consists of a corrugated tube having the crests 17 thereof fused to the turns of the coil 12 and in elastic contact with the crests 17a of a corrugated tube forming the sheath 15, the troughs 16, 16a of the sheaths 14, 15 being spaced from each other by a narrow air space 18. More than one additional sheath may surround the sheath 14, each being spaced from the other by an air space. The wire 12 is coated with plastic by passing through an extruder and the sheaths 14, 15 are formed by extrusion. The material for coating the wire 12 and of which the sheaths are made may be natural or synthetic rubber, polyamides, polyethylene, polyvinyl chloride, polyvinyl acetate, vinylidene chloride or a polyurethane. In making the conduit the sheath 14 is expanded in a vacuum expander box and the coil 12 previously tensioned is inserted in the sheath which is then allowed to contract over the coil. Fusion of the plastic coating of the coil with the sheath 14 is then obtained by passing electric current through the coil. The sheath 14 with the coil therein is then introduced in the sheath 15 which is similarly expanded in a vacuum expander and then allowed to contract over the sheath 14.