METHOD AND APPARATUS FOR ZERO ADJUSTMENT OF PRESSURE DETECTOR IN INJECTION MOLDING MACHINE

摘要

A method and an apparatus for making a zero adjustment of a pressure detector on an injection molding machine, in which the external load acting on the pressure detector is completely removed without disassembling its injection mechanism. While a screw (7) is driven in a low output condition, a forward limit position (Qf) and a backward limit position (Qb) are detected to determine the intermediate position (Pm) between them. The screw (7) is then moved to the intermediate position (Pm) to completely remove resin reaction acting directly on the screw (7). Reciprocating motion the amplitude of which decreases progressively is applied to the screw (7) to generate a backlash, i.e., an equal play between a ball nut (9) and a ball screw (8) in both forward and backward directions, and thus a zero adjustment of a load cell (10) is carried out under the state where the pressure acting on the load cell (10) is completely removed.