| 摘要 |
PURPOSE:To manufacture a resin-coated steel pipe efficiently, whose dimensions of an external diameter and roundness are accurate, by a method wherein a heated steel pipe is sent into the titled device, on the surface of which molten resin is extruded and coated, and compression sizing is done further. CONSTITUTION:Resin B molten and plasticised by a material supply part 11 of an extruder 1 passes through a flow path 124 provided between an inner die 122 and an outer die 123 incorporated into a head die such as a crosshead die or an angle head die and supplied to a front die 13 continuously. When coating resin B is moved simultaneously with movement of a steel pipe after the same is come out of the front die, a temperature of the surface of the resin B is lowered through discharge of heat into the air, curing is progressed and led to a sizing device further. Each throttle ratio of an extruder and a sizing device is made into 0.90-0.98 and a length of a flow part of the front die of the extruder is made into 3-8 times of a necessary coated resin thickness. |
