| 摘要 |
PURPOSE:To obtain the titled apparatus that gives a covered steel pipe having impact strength wherein the adhesion of resin is good, and the thickness of cover is uniform, by arranging a ring-shaped water-cooling apparatus in connection with a cylindrical extrusion die, and providing a resilient roll for pressing the foot section of the steel pipe bead section during the water cooling. CONSTITUTION:In covering a steel pipe with plastics using a cylindrical die, the ring-shaped water-cooling apparatus for cooling the plastic covered steel pipe is arranged in connection with the extrusion die, and to press the foot section of the bead section 1 of the steel pipe 3 during the water cooling, the solid resilient roll 6 that will conform with the outer diameter of the steel pipe 3 and has a recess 5 in conformity with the bead 1 is arranged to press the plastic film 4 at the bead section 1. Thus, the gap 2 between the bead section 1 and the plastic film 4 is eliminated to obtain the covered pipe wherein the adhesion between the steel pipe 3 and the film 4 is good. |
