| 摘要 |
PURPOSE:To stably mold a reinforcing rib even if the thickness of a product is 40mm or more by setting an initial blowing pressure to a specific value or less, slowly shaping resin, and then raising a blowing pressure to a specific value or more at a stage in which the shaping is substantially completed. CONSTITUTION:When a parison 10 of synthetic resin is inserted into blowing molds 11 and molds are clamped, a slide plate 14 is allowed to protrude inside the molds 11 to partly pressurize the parison 10, the pressurized part is molded in a plate state to obtain a reinforcing rib 9. Here, an initial blowing pressure is set to 3kg/cm<2> or less, the resin is slowly shaped, and a blowing pressure is raised to 4kg/cm<2> or more at a stage in which the shaping of the rib 9 is substantially completed. Since the parison 10 is slowly swelled under low pressure at the initial time, excess stress is not applied to the parison pressurized by the plate 14, and the blowing pressure is raised simultaneously upon completion of shaping of the rib 9, thereby stably obtaining a molded form. |
