Van Dorn Demag Corporation

Thomas H Richards

Thomas Christopher Bulgrin

George L Eterovich

Alexander M Galan

An energy efficient general purpose injection molding employs a hydraulic drive for injection and clamp machine functions and an electric drive for screw recovery. Both drives use AC &ldquo;squirrel cage&rdquo; induction motors under vector control. Speed command signals for the vector controls are generated by the machine's controller utilizing state transition and predictive signal techniques to account for motor and motor/pump response latencies. Hydraulic drive efficiency is improved by varying motor speed/pump output to match cycle requirements to retain hydraulic drive advantages for mold clamp and injection functions while improving the electric drive performance for screw recovery.

Hybrid injection molding machine

An energy efficient general purpose injection molding employs a hydraulic drive for injection and clamp machine functions and an electric drive for screw recovery. Both drives use AC 'squirrel cage' induction motors under vector control. Speed command signals for the vector controls are generated by the machine's controller utilizing state transition and predictive signal techniques to account for motor and motor/pump response latencies. Hydraulic drive efficiency is improved by varying motor speed/pump output to match cycle requirements to retain hydraulic drive advantages for mold clamp and injection functions while improving the electric drive performance for screw recovery.

A control system utilizing a programmable controller for an injection molding machine in which the controller is periodically scanned in response to input signals to produce output control signals is provided with an impulse response filter arrangement. The impulse response filter senses a plurality of current and past sensor input signals to accurately predict the occurrence of a variable triggering event which will in fact be sensed by a sensor. A predictive sensor signal is then generated which is inputted to the controller in advance of the occurrence of the triggering event and at a time which corresponds to the processor scan time so that the controller generates the desired output at the precise time the triggering event occurs thus eliminating controller response latency from the control system.

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Brunswick Hills, OH, United States of America

Thomas H Richards