| 摘要 |
PURPOSE:To manufacture a blow molded product of uniform wall thickness by applying the pressure resistant to the pressure of pressurized fluid at a flowing end where molten resin is pushed and moved by the pressurized fluid. CONSTITUTION:Molten resin is injected into a cavity. Then, pressurized fluid, preferably pressurized gas, is injected directly into the molten resin. To carry out the injection, a needle 6 with its end positioned in the cavity is provided in a mold. As the pressurized fluid is injected, a hollow is generated in the molten resin, and the hollow grows up and simultaneously the molten resin is pushed toward a cavity space 7 and moved. At that time, the pressure of pressurized gas in the cavity space is applied resistively to the flowing end of resin. Thus a hollow is formed in the molten resin. When the flowing end of resin gets close to the end of the cavity, or while the resin flows through the end already, the gas pressure at the end of the cavity is released. Then the resin reaches the end of the cavity to form a hollow mold material. |
