| 摘要 |
PURPOSE:To prevent a perform from deforming when a mold core is released from the preform by forming a number of fine recesses into which flowing of molten resin is difficult to be done and which allow the air to remain at the time of forming the preform on a surface layer on the side lower than a mouth section of the mold core. CONSTITUTION:A number of fine recesses 14 of 0.03mm or smaller into which the flowing of molten resin is difficult to be done and allow the air to remain at the time of forming a preform are formed all over a surface layer on the side lower than a mouth section forming section 11a of mold core 11. Such a mold core 11 runs through a lip mold 13 form above and is inserted into a cavity mold 10, and when molten resin is injection filled from a gate of a cavity mold bottom section into the cavity after mold clamping to form a preform 12, the air remains intermittently in the surface layer by means of respective recesses 14. Releasing is carried out while said preform is of high temperature and in the softened state. First the mold core 11 is moved upward together with the lip mold 13, and the preform 12 is released from the cavity mold 10, and further the mold core 11 is moved upward to release the preform 12 retained by the lip mold 13. |
