| 摘要 |
PURPOSE:To improve the strength of bottom part of a drawing blow-molded vessel and thus obtain an excellent heat resistance deformability and inner pressure resistance by stretching the part situated lower than the step formed on the outside surface of continuous part of a first and second barrel part once in the longitudinal direction and diameter direction. and then heat-maintaining it higher than the crystallization temperature of plastic for its spontaneous contraction. CONSTITUTION:A preliminary molding 1(44) comprises two parts having different barrel parts in their diameter and, on the outer surface of a part wherein a first barrel part 12 and a second barrel part 13 are continued, a step 15 is formed. The preliminary molding 44 is installed within a mold 3 and, by releasing valves 41 and 42, the same compressed gases therewith are blown respectively into the gaps of the inner part and bottom lower side in the preliminary molding 44, thereby forming a preliminary molding 2. Next, while effecting gas-extraction from the gap of bottom lower part of the preliminary molding 2 and pressing a stretching rod 39 downward, gases are blown into the preliminary molding for conducting the orientation of a part lower than the step 25. Thereafter, gas pressures in the inner part of the preliminary molding is lowered and, while heating and maintaining the oriented barrel lower part 44 and bottom part within a mold 3 (bottom mold 33), the oriented barrel lower part and bottom part are subjected to spontaneous contraction. |
