| 摘要 |
PURPOSE:To prevent the defective appearance of a molded product by injecting a circular parison out of circular die, expansion preforming the parison by means of a parison expanding means disposed on the lower end of a mandrel, pinching the same by a pinching device and again expansion preforming the parison into the flat shape by means of the parison expanding means after the completion of hanging between split molds. CONSTITUTION:A circular parison 13 is preformed into a flat parison 13 by extruding the parison 13 a little from a die 9, stretching piston rods 18bL and bR by means of cylinders 18aL and aR of a parison expanding device 18, and pinching devices 14a and (b) are brought close together, and the lower section of the parison 13 is pinched to form the closed-end parison 13. The piston rods 18bL and bR are moved back to the backward positions and the pinching device 14 is brought back to the open state after the expansion of the parison 13. Successively the lower end of the flat parison 13 is hung down to the state of positioning a little below split molds 10a and (b) and stopped thereon, and then the upper section of parison 13 is preformed from the circular parison 13 into the flat parison 13 by the parison expanding device 18. The pinching device 14 is left in the open state. |
