| 摘要 |
PURPOSE:To form a hollow molding whose shoulder thickness in the circumferential direction is uniform by a method in which a temperature difference is produced between the head and shoulder of a parison and then the drawing blow molding of the parison is made. CONSTITUTION:The tip 36a of a blow core is inserted into and contacted with the inside diameter portion of the head 38a of a parison and thereby the head 38a of the parison is quickly cooled. At the same time as a draw rod 53 is lowered, compressed air is supplied to the shoulder 38b and torso 38c of the parison for drawing blow molding. Whereupon, a great temperature difference is produced in the boundary between the head 38a touched by the core 36 and the shoulder 38b not touched by the core 36, and the shoulder 38b and the torso 38c are sufficiently stretched by drawing blow molding to form a hollow molding 38' in which the thickness is abruptly changed between the head 38a' and the shoulder 38b' of the molding. Hollow moldings 38' having uniform thickness in the circumferential direction can thus be obtained. |
