Synchronized Injection Molding Machine with Servomotors

Injection Molding Machine (IMM) is one of the most important equipment in plastic industry. As a cyclic process, injection molding can be divided into three steps includes filling process, packing-holding process and cooling process, among which filling process and packing process are both most important phases for the quality of part, and the corresponding crucial process variables are injection velocity and packing pressure in filling and packing phases. Moreover the determining a suitable injection time, screw position and cavity pressure for transfer from injection velocity control to packing pressure control which is commonly called filling to packing switchover point is also critical for high quality part. This study is concerned with two research aspects: double servomotors synchronization control for injection unit, and filling to packing switchover methods. The simulation result of switching method based on injection time and ball screw position those are similar, and the result of switching method based on the cavity pressure that is better.