MANUFACTURE OF FORMING FLUORINATED RESIN INSULATIVE WIRE

摘要

PURPOSE:To improve foaming ratio and contactness of a stranded wire and a foaming layer by using the stranded wire as a core wire, preheating the stranded wire and decompressing the inside of a nipple in a cross head. CONSTITUTION:A stranded wire of copper or aluminium is used as a core wire 11. A heater 17 is arranged before a cross head 14 for preheating a stranded wire 11 and a decompressor 18 is arranged at an inlet of a nipple 15 for decompressing the inside of the nipple 15. The decompressor 18 is provided with a pressure-difference exhausting chamber 19 and a vacuum exhausting chamber 20 to be vacuumed out respectively by a vacuum pump in order to keep the inner pressure of the nipple 15 under 700Torr while the stranded wire 11 is passed through the nipple 15. A temperature for preheating the stranded wire 11 is such as about 150 deg.C. Accordingly, a fluorinated resin including foaming agent 12 extruded and coated sufficiently foams without thermal conduction to the stranded wire 11. Foaming gas is passed through the gap in the stranded wire 11 and absorbed backwards to form a thin membrane 12c on the surface of the stranded wire 11. Contactness of a foaming layer 12b and the stranded wire 11 is thus improved.