Other

Ravinder Venugopal

Ananthakrishnan Surianarayanan

Sameer Anand Joshi

A method/system for achieving force control in externally driven hydraulic/gas-filled cylinders estimates effective flow parameters based on sensor measurements, and predicts desired flow parameters for force control objectives and determines required control actuation signals. The system selectively uses pressure sensors to measure the pressure of fluid in each (hydraulic) cylinder, displacement sensors to measure the displacement of the piston in each (hydraulic) cylinder, piston velocity sensors or piston velocity estimators, manifold pressure sensors or manifold pressure estimators, converters that digitize analog signals from the sensors, a microprocessor capable of storing data from the converters and producing actuator signals, and flow regulating actuators responsive to the actuator signals for regulating the flow of (hydraulic) fluid out of each cylinder by changing the effective flow-area of flow ports. The invention can be used in hydraulic or gas-filled cylinder arrangements applied to die-cushions in stamping presses and active/semi-active shock absorbers.

Method and system for achieving force control in externally driven hydraulic cylinders

A reconfigurable variable blank-holder force system (and method) for producing sheet metal stampings comprises a portable hydraulic unit, controlled by a digital control system and a knowledge-based expert system to enable reconfigurability and an easy transition from the try-out stage to production. The knowledge-base has a hierarchical structure and includes stored information about part geometry, material properties and press parameters. The expert system enables an operator to determine optimal blank-holder forces, and to fine-tune through a graphical interface unit. The optimal blank-holder forces are generated by hydraulic force actuators, using a controller running a nonlinear algorithm that accounts for valve nonlinearities, variable flow-rate and numbers of operational cylinders. The portable hydraulic unit preferably comprises hydraulic cylinders with quick disconnect hoses, a manifold, servo-valves and a pump unit. A structured method to utilize this system to produce sheet metal stampings is also described. An article embodying the method is included.

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Montréal, Canada

Ravinder Venugopal