Abstract: An injection molding machine utilizing vector controlled AC induction motors in its servomechanism drive systems. Vector controlled AC induction motors provide a cost effective high power drive system which superior performance capabilities. Further system efficiencies are realized when the control is configured to run multiple motors by multiplexing the computer controller circuits for the power sections of each motor.

Abstract: A hydraulic injection molding machine incorporates a pump driven by a variable speed motor preferably of the brushless DC type. The machine controller outputs driving signals to adjust the speed of the motor so that the flow delivered by the pump substantially matches the hydraulic demand imposed during each phase of the machine operating cycle. The pump is preferably a variable displacement type and is connected to a fast responding pump control for selectively carrying out pressure compensation or flow compensation. The values of the motor driving signals are calculated so that the motor/pump combination is operated at or near maximum efficiency except when the pump control varies the displacement of the pump to effect pressure or flow compensation. Hydraulic transient response is further improved by connecting the output of the pump to an accumulator by way of a check valve.

Abstract: An injection molding machine utilizing brushless DC motors in its servomechanism drive systems. Brushless DC motors provide a cost effective high power drive system which has the simplicity of control of brush-type DC motors. By utilizing higher resolution encoders and controlling pressure with the servomotor velocity control loop, motor cogging and zero velocity oscillatiions are minimized.