Control of an Injection Molding Machine: Adaptive Regulation During Filling

An adaptive control algorithm, the self-tuning regulator (STR), was applied to control the injection phase of an injection molding machine cycle. The objective was to control the hydraulic pressure and cause it to follow a predetermined profile. The information of the previous cycle was used to correct the controller parameters for the next cycle. This computation is done between cycles. The STR control was found superior to standard proportional-integral control of the same system when high density polyethylene was injected into a heat distortion temperature test mold. Both algorithms had trouble controlling when acrylonitrile-butadiene-styrene was injected into a flex bar mold. A number of potential directions are proposed to improve the control for the latter conditions.