Pressure abnormality detecting device for injection molding machine

摘要

An injection screw position Xa, injection speed Va, and injection pressure Pa are read. A deceleration distance D the injection screw moves from the point where the injection operation has been stopped at the current moment to be decelerated by_maximum deceleration till the point where the injection speed is reduced to zero is determined from a corrected deceleration in which the amount of correction α is added to a predetermined deceleration A inherent in the machine and the read injection speed Va. The determined deceleration distance D is multiplied by the amount of change in injection pressure with respect to the amount of change in the injection screw position to determine a predicted increment in pressure (D·ΔP/ΔX). The predicted increment in pressure is added to the current injection pressure Pa to determine an injection pressure Pa* predicted when the screw is suddenly decelerated at the current moment. If the predicted injection pressure Pa* exceeds the predetermined limit pressure Pmax, the injection operation is stopped to decelerate the screw.