ELECTROHYDRAULIC DRIVE FOR PROCESS LINE WINDERS,UNWINDERS AND OTHER EQUIPMENT

摘要

An electrohydraulic drive for process line equipment, especially a spooler that winds and pays out an indefinite length of metallic strand, varies the output torque of a hydraulic motor by controlling its displacement and the pressure differential between its inlet and outlet. A valve controlled by a proportional actuator reduces the supply pressure of the hydraulic fluid in a feed line for the motor. A sequence valve located in a return line from the motor maintains the pressure at the motor outlet at a preselected and adjustable value. During braking, fluid from the return line is directed to a regeneration circuit that includes a flow divider. A portion of the flow is returned to the feed line to conserve the fluid flow. Another portion is returned to a supply reservoir for cooling. A servo-amplifier circuit includes an integrating amplifier that compares the actual rotation speed of the motor to a speed command signal. An analog multiplier produces a control signal for the proportional actuator that is the scale product of the output signal of the "speed" amplifier and a pressure limit signal. In the preferred form a tensiometer monitors strand tension and produces an input signal to a computer that modifies the pressure limit signals. The computer interfaces with other input and output devices and also controls the speed command and displacement of the motor. An hydraulic cylinder controls the linear traversing movement of the spooler under the control of a high speed servo valve that in turn is controlled by electronic circuitry. Position, velocity and rotation speed transducers for the spooler and a position transducer for the strand provide input signals to the circuitry.