Application of advanced control theory to enhance molding machine performance

The computing power and system design of recent custom designed control systems makes possible the application of modern control theory in injection molding machines to achieve new standards of performance without expensive, special purpose equipment. The new line of controls from the Van Dorn Demag Corporation uses digital filters, state transition logic, and high order temperature state control to control more accurately the molding machine process. The use of digital filters together with state transition logic reduces the controller response time latency, improves cycle-to-cycle repeatability, and predicts future positions of the molding machine clamp for use in clamp braking. The temperature state control system uses real-time mathematical modeling of the barrel and tracking of estimated thermal disturbances to better control the barrel temperature, These techniques are applied to a wide variety of injection molding machine types and sizes and can be done in a way which makes the programming and operation of the machines less difficult than with traditional methods.