Injection molding is the most prominent way to produce components made of plastics. In the injection molding process, plastics is liquefied by means of heating and deformation of the granulate. The liquid plastics is accumulating in the screw antechamber. If the screw is moved forward, the liquid fluid is injected into the mold. After sufficiently cooling down, the final plastics part can be taken out of the mold and the process can begin again.
To obtain a high product quality during production, the stability of the injection process from one injection cycle to the next is of outmost importance. The main process variables in injection machines are the temperatures, the injection velocities and the injection pressures. Suitable control strategies are therefore necessary to obtain exact and reproducible tracking of the desired values for these quantities. In this research project in cooperation with Engel, optimal control strategies are developed for the injection and holding pressure phase (velocity, pressure) as well as the temperature for injection molding machines. One focus of this project lies on hydraulic actuated injection molding machines with hydraulic direct drive (servo-pump), which feature an improved energy efficiency compared to valve controlled machines. The control of these machines is particularly demanding due to the reduced dynamics of the actuation system.