| 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 the correction number of rotations and setting this correction number of rotations to the corrected set number of rotations of a screw 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 the correction number of rotations. The correction of the set number of rotations of the screw is performed on the basis of this correction number of rotations and the temp. of the molten resin is controlled so as to become desired temp. until the next extrusion supply. |
