Electrohydraulic system

• Main Authors: SILVERTHORN, RANDALL G, GUNDA, RAJAMOULI, EL-IBIARY, YEHIA M, SMITH, PAUL M, DAHROUG, MOHAMED E
• Format: Patent
• Language: English; French; German
• Published: 24.10.1990
• Subjects: AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; BLASTING; CASTING; CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES; CONTROL OR REGULATING SYSTEMS IN GENERAL; CONTROLLING; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR; FLUID-PRESSURE ACTUATORS; FLUID-PRESSURE ACTUATORS, e.g. SERVO-MOTORS; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; HEATING; HYDRAULICS OR PNEUMATICS IN GENERAL; LIGHTING; MECHANICAL ENGINEERING; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS ORELEMENTS; PERFORMING OPERATIONS; PHYSICS; POWDER METALLURGY; REGULATING; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; TRANSPORTING; WEAPONS; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL

In a die casting machine that includes a shot cylinder having a ram for injecting metal into a die cavity, an electrohydraulic system for controlling operation of the shot cylinder includes an actuator coupled to the shot cylinder ram. A valve supplies hydraulic fluid to the actuator cylinder as a function of valve control signals. Microprocessor-based digital control electronics includes memory for storing a desired ram velocity profile as an incremental function of ram position. The control circuitry is responsive to signals from a sensor coupled to the actuator, indicative of position at the ram, for retrieving corresponding velocity signals from memory and supplying control signals to the valve as a function of such profile velocity signals. The control circuitry further includes facility for adjusting impact of the shot cylinder ram at the end of a cavity-filling stroke as a function of ram and actuator position and/or pressure, independently of the velocity/position profile, to reduce separation and flashing at the die cavity, and to reduce impact wear and fatigue on the overall die casting machine. A keyboard and associated operator display provide operator programmability and selection from a plurality of velocity/position profiles. The actuator and cylinder ram may be advanced in a manual mode of operation for adjustment and calibration proposes. A display associated with the keyboard graphically illustrates desired and actual velocity/position profiles during operation, together with a profile of actuator drive pressure verses position.