| 摘要 |
PURPOSE:To obtain easily the covered object by high foaming extrusion having the sound core shape without deformation by using the trumpet-shape one for the land of the exit tip of the die of an extrusion machine, when the covering of high foaming extrusion by gas-foaming process is carried out. CONSTITUTION:(1) In the covering method of high foaming extrusion using gas a foaming agent which is suitable for the production of the extruded and covered electric wire insulated by the foam with at least 3 of expansion ratio, the land of the exit tip of the die of an used extrusion machine has a trumpet shape on the part of the land has a trumpet shape, and (2) the thickness of the insulating layer is in the range of 2-7mm, (3) the expanded angle of the trumpet shape-land is 2-8 deg. and (4) the gaseous substance such as nitrogen, argon or carbon dioxide, etc., of the temperature of at least 100 deg.C and the pressure of at least 300kg/cm2 is used as the foaming gas. |
