Plastic sheaths for metal wires

摘要

In a process for making a plastic sheath for metal wires, a tube of plastics material of uniform wall thickness is injected on a hollow mandrel and the wire advances at a speed considerably greater than that of the tube injected concentrically on it. The plastic material is hardenable by a catalyst mixed with it and/or by elevated temperature and/or high energy radiation. The invention is esp. for plastic sheaths 100 mu thick covering wires of section 7 mm2. The wire is pref. heated before coating. The thermosetting material which is pref. liquid or plastic is pref. passed through a mixing head in which partial hardening takes place so that it achieves the viscosity required for injection. The plastic material pref. hardens without evolution of gases. Thin coverings for wires of small diameter can be produced at high speeds.