Physically-based adaptive control of cavity pressure in injection moulding process: packing phase

Cavity pressure plays an important role in determining the quality of injection moulded article. However, the non-linear and time varying behaviour of the process causes difficulties in implementing efficient control systems, since these generally employ linear time invariant design strategies. Conversely, advanced control methods, such as self-tuning, do not provide physical information about the process. A physically-based adaptive controller has been developed for cavity pressure control during the packing phase. Experimental results indicate that this control yields accurate results for the injection moulding of polyethylene. Different control algorithms with different tuning criteria were implemented on a microcomputer to control the cavity pressure. The results also show that this method is superior to the classical empirical control approach.