| 摘要 |
PURPOSE:To form uniform and even rugged surface on a whole peripheral surface of a rod member by a method wherein a step is provided between fore and aft land portions of a metallic mold for an extrusion molding machine and polyethylene resin, added with a forming agent, is covered on a rod member during extrusion and is foamed at the fore land portion. CONSTITUTION:Polyethylene resin material, added and blended with a forming agent, is thrown into a hopper, not shown in a diagram, for an extrusion molding machine, and is heated and softened by a heater 11 provided on an outer peripheral surface of a cylinder 2, thereafter, is supplied sequentially into a resin passageway 8 at a molding portion 4 by rotation of a screw 1. On the other hand, a rod member 12 of a metal or the like is supplied from right to left through core member passageway 7 in a nipple 5, while the resin A is covered sequentially on the surface of the rod member 12 at an aft land portion 9 in the molding portion 4. Subsequently, the resin A is formed in a fore land portion 10, formed to have a bigger diameter, and thereby, an uniformly rugged covering for the rod member 12 may be formed. |
