MANUFACTURE OF HOLLOW SYNTHETIC RESIN PRODUCT

PURPOSE:To obtain a hollow synthetic resin product with a double tubular structure by one process by a method wherein parison is constituted so as to have the double tubular structure consisting of inside parison and outside parison and, after the parison and a mandrel are introduced in a forming mo...

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1. Verfasser: NISHIGORI KAZUHIKO
Format: Patent
Sprache:eng
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Zusammenfassung:PURPOSE:To obtain a hollow synthetic resin product with a double tubular structure by one process by a method wherein parison is constituted so as to have the double tubular structure consisting of inside parison and outside parison and, after the parison and a mandrel are introduced in a forming mold, the mold is closed and finally blowing pressure is applied between the inside parison and the outside parison in the forming mold so as to expand the parison. CONSTITUTION:Parison 12 is lowered until the lower end bent part of inside parison 12a and outside parison 12b reaches the predetermined position or near the lower edge part of the mold surfaces 16 of a forming mold 14. Next, the forming mold 14 is closed so as to pinch the parison 12 between a mandrel 21 located at the center of the mold and the mold. Next, by projecting the tip part of the needle pipe 20 of one mold half 15a beyond the mold surface 16, the needle pipe is pierced in the outside parison 12b so as to feed air between the inside parison 12a and the outside parison 12b in order to expand the inside parison 12a along the surface of the mandrel 21 and simultaneously the outside parison 12b along the mold surfaces 16 of the forming mold 14. After that, the needle pipe 20 is retreated. Thus, a formed item with a double tubular structure consisting of an inner tube 3 having the shape along the surface of the mandrel 21 and an outer tube 5 having the shape along the mold surfaces 16 of the forming mold 14.