| 摘要 |
PURPOSE:To provide a manufacturing method wherein when a hollow body like a pipe or the like is continuously manufactured by extrusion molding of a synthetic resin, even for a thick wall molding, the molding which is little in deformation like a sink-mark, shrinkage on an edge face, etc., can be obtained in high productivity. CONSTITUTION:Extrusion covering is once or a plurality of times applied to an outer surface of a continuous hollow body for molding an inner layer consisting of crystalline resin by using the crystalline resin of the same composition while the continuous hollow body for molding the inner layer is being transferred in one direction to mold an outer layer. Thereby, a molding of a specific wall thickness is obtained. Then, a difference in cooling temperature between the outer layer and the inner layer in shaping decreases, and strain in molding is reduced. |
