Nozzle touch apparatus in an injection molding machine

Abstract

A nozzle touch apparatus (5) for use in an injection molding machine, which is capable of automatically adjusting a nozzle touch force in a multi-stage fashion during execution of an injection molding cycle, having springs (56) each fitted on a guide rod (52) and disposed between a ball nut (54) and an extension portion (43) of an extruder base of an injection unit (4), the guide rod being formed integrally with the ball nut which is threadedly engaged with a ball screw (52) coupled to a servomotor (51) and inserted through a hole (43a) formed in the extension portion. The nozzle touch apparatus further includes a servo circuit (63) supplied with a signal from a strain gauge (61) provided on the extension portion and indicative of an actual nozzle touch force, and a signal supplied from a numerical control unit (64) and indicative of a predetermined nozzle touch force. The servo circuit is operable to drive the servomotor in accordance with a deviation between these signals to cause the guide rods to move, whereby the springs are brought into a compressed state in which the actual nozzle touch force consistent with the predetermined nozzle touch force is generated, the predetermined nozzle touch force being changed to a smaller value upon shift from a mold closing process to a mold opening process, thereby preventing deformation of a mold in the mold opening.

Dependencies are inferred from the claim text.