| 摘要 |
A wide-mouthed container bottom molding method using stretch blow molding, wherein the barrel and bottom of a preform are separately stepwise stretched, whereby the bottom, like the barrel, of a wide-mouthed container can be molded to have an optional bottom surface that is thin-walled with a uniform thickness distribution. A blow mold (11) is used for subjecting a preform (1), obtained by integrally forming a short cylindrical thick-walled barrel (2) and a sheet-like thin-walled bottom (3) connected to the lower end of the barrel, to stretch blow molding to provide a wide-mouthed container (4, 5), the blow mold (11) having a bottom form (13) that is movable in a cavity (12). A stretch rod (16) is used that has both a core member (18) for pressing the central portion (3b) of the bottom (3) and a skirt member (19) positioned around the core member (18) to press a corner (2a). Stretching by the stretch rod (16) is applied to the barrel (2) and bottom (3) of the preform (1) separately such that either is stretched first until the barrel (2) reaches a cavity bottom edge (11b). The bottom (3) positioned on the bottom form (13) sunk onto the cavity bottom is further stretched such that it is pushed back into the cavity by the bottom form (13) and turned upward from a cavity bottom edge (11b).
|
