Abstract: A preform heating method for heating a preform for a stretch blow molding is executed by an apparatus which comprises an outer heating die having a cavity for the preform, a thermal-insulating pot surrounding the outer heating die and a high-frequency heating unit installed around to the thermal-insulating pot. The heating of the preformed is executed by locating the heating die around the preform, applying alternating magnetic flux to the heating die to heat the preform through the heating die, and controlling the magnitude of the alternating magnetic flux to control the temperature of the preform.

Abstract: A method of controlling a blow molding machine from a completion of production of one product to a start of production of a next product comprises controlling a temperature of a resin within the blow molding machine, controlling an operation of devices from the completion of production of the one product to the start of production of the next product, controlling a sequent transport of some of the devices in predetermined positions, and controlling a change of the resin in accordance with a supply stop thereof and a data on the next product.

Abstract: A method of controlling a blow molding machine from a completion of production of one product to a start of production of a next product comprises controlling a temperature of a resin within the blow molding machine, controlling an operation of devices from the completion of production of the one product to the start of production of the next product, controlling a sequent transport of some of the devices in predetermined positions, and controlling a change of the resin in accordance with a supply stop thereof and a data on the next product.

Abstract: A method of controlling a blow molding machine from a completion of production of one product to a start of production of a next product comprises controlling a temperature of a resin within the blow molding machine, controlling an operation of devices from the completion of production of the one product to the start of production of the next product, controlling a sequent transport of some of the devices in predetermined positions, and controlling a change of the resin in accordance with a supply stop thereof and a data on the next product.

Abstract: A parison length control method for a blow molding machine in which a parison is extruded vertically, the end of the parison is closed, and a blowing gas is blown into the closed parison. The method includes the step of deriving a relationship between parison length and extruder screw rotation speed during a test molding process. Current parison length is then detected during normal molding operation, and the difference between the current parison length and a target parison length is derived. The extruder screw rotation speed is then controlled by calculating a correction amount for the extruder screw rotation speed based on the parison length difference in combination with the relationship between parison length and extruder screw rotation speed. The extruder screw rotation speed is then adjusted by the correction amount so as to attain the target parison length.

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.