SELF-TUNING CAVITY PRESSURE CONTROL OF INJECTION-MOLDING FILLING

Cavity pressure is an important process parameter for injection molding control. However, the nonlinear and time-varying behavior of cavity pressure cause some difficulties in implementing a control system based on commonly used linear, time-invariant design strategies. In this work, the nonlinearity and time-varying characteristics of cavity pressure are examined for the mold filling phase. A self-tuning controller has been developed, implemented, and tested for both regulating and tracking purposes over a wide range of conditions. It is found that the proposed control system can automatically adapt itself to different operating conditions, yielding quite accurate control. (C) 1994 John Wiley & Sons, Inc.