| 摘要 |
PURPOSE:To stabilize the viscosity of a resin and to make the length of a parison constant by measuring the temp. of the molten resin in an extruder to calculate the difference with the previous resin temp. and integrating a proportionality factor with this difference to calculate correction temp. and setting this correction temp. to the corrected set temp. of a heater to perform temp. correction. CONSTITUTION:The pellet like resin in a hopper 36 is supplied to the inner hole 33a of an extruder 33 and melted under heating while a screw 35 is rotated and the molten resin 15 is stored in an accumulator 32 while a plunger 38 is allowed to retreat. Next, when the plunger 38 is allowed to advance, the resin 15 is supplied to a die 10 through a resin passage 31 to be molded as a parison 50. At this time, the temp. of the molten resin 15 extruded from the extruder 33 is measured to calculate the difference with the previous resin temp. and a proportionality factor preliminarily obtained on the bases of a rule of thumb is integrated with this difference to calculate correction temp. This correction temp. is set to the corrected set temp. of a heater 37C to perform temp. correction. By this method, the viscosity of the resin is stabilized. |
