Abstract: The invention resides in a rotary blow molding machine in which under an extruder for extruding a parison, a turntable is arranged which has plural sets of molds mounted thereon for holding the parison therebetween and blow-molding the parison, the turntable is rotated by a motor, an annular driven gear is provided on the turntable, and one pair of idle gears are made to intervene between the driven gear and a driving gear for transmitting the rotation of the motor so as to intermesh with both the gears.

Abstract: The invention resides in a rotary blow molding machine in which under an extruder for extruding a parison, a turntable is arranged which has plural sets of molds mounted thereon for holding the parison therebetween and blow-molding the parison, the turntable is rotated by a motor, an annular driven gear is provided on the turntable, and one pair of idle gears are made to intervene between the driven gear and a driving gear for transmitting the rotation of the motor so as to intermesh with both the gears.

Abstract: A parison thickness control system includes an extruder die and a mandrel which are movable relative to each other to change wall thickness of a parison extruded between the extruder die and the mandrel during an extrusion or forming cycle of the parison. A parison control pattern is derived by manually inputting master points each defined in terms of a target parison wall thickness and an elapsed time during the parison extrusion cycle. A further parison control pattern is derived by performing the spline interpolation to interpolate between the master points. A still further parison control pattern is derived by correcting the above-noted further parison control pattern to allow the maximum or minimum value of the master points to indicate a limit value for the target parison wall thickness during the parison extrusion cycle. The parison extrusion cycle is divided into a given number of equal time intervals to define cycle points.