Patent ID: 6468449
Filing Date: 2002-10-22
Classification: B29C

Abstract:
A mold opening control method for an injection molding machine, said injection molding machine performing mold opening and closing by moving a mold clamping axle of a movable platen with a mold opening and closing screw rotating by a servo motor, performing mold clamping by pushing a mold clamping ram in a support platen hydraulically with a half nut device closed, said half nut device having half nuts attached to the mold clamping ram, and said half nuts meshing with protuberances of the mold clamping axle, and performing a mold thickness adjustment by a first detection device for detecting the relative position of the mold clamping ram with respect to a support platen, a second detection device for detecting the position at which the half nut device engages the mold clamping axle, and a mold clamping ram position control device for hydraulically controlling a position of the mold clamping ram with respect to the support platen, comprising:making a selection between two mold opening modes: a standard mold opening mode in which the mold opening operation is performed by the servo motor with the half nut device open, and a strong mold opening mode, said mode comprising the step of: initially retracting the mold clamping ram hydraulically and strongly with the half nut device continuing to be closed and with the first detection device detecting the mold clamping ram position, stopping the mold clamping ram at an initial mold opening position where the movable platen actually opens, returning the mold clamping ram to a return position where the half nuts opens without contacting the protuberances of the mold clamping axle, stopping the mold clamping ram at the return position, opening the half nuts, returning the mold clamping ram to the mold thickness adjustment position hydraulically, and, shifting to the strong mold opening mold step to the standard mold opening mold step.