Pressure Profile Trace Control on Fully Electric Injection Molding Machine. (1st Report). Application of Learning Control for Flow Pressure Control.

Abstract

In case of plastic injection molding process, stable molding is the most required and pressure profile deviation under injection velocity control is used for a judgment factor of stable molding. Formerly pressure profile is controlled only during hold process (pressure controlled stage) and is not controlled during injection process (velocity controlled stage). To achieve the stable injection process, Pressure Profile Trace Control is developed. This control is able to trace the original pressure profile at good part produced by controlling pressure directly. To control pressure directly with fully electric injection molding machine, the force control of electric servomotor has to be used. Force control of electric servomotor is developed for various areas, especially robot application. But there is a little application at injection molding area. Simple closed loop force control was not able to get good result. To improve the functionality, learning system is introduced for force control.