NOZZLE TOUCH DEVICE FOR INJECTION MOLDING MACHINE

摘要

A nozzle touch device (5) for an injection molding machine, which can automatically regulate in multiple stages the nozzle touch force during the execution of an injection molding cycle includes a guide rod (52) which is integral with a ball nut (54) meshing with a ball screw (52) connected to a servo motor (51) and which passes through a hole (43a) bored in an extension (43) of an extruder base of an injection unit (4); a spring (56) which is fitted over the guide rod and interposed between the ball nut and the extension; and a servo circuit (63) to which a signal representing an actual nozzle touch force from a strain gauge (61) disposed on the extension and a signal representing a predetermined nozzle touch from a numeric controller (64) are supplied. The servo circuit drives the servo motor in accordance with the difference between these signals to move the guide rod, and compresses the spring to a compression state where an actual nozzle touch force in conformity with the predetermined nozzle touch force is generated. Deformation of the mold at the time of mold opening is prevented by changing the predetermined nozzle touch force to a smaller value at the time of shift from mold closing to mold opening.