Multimodal control of the main hydraulic directional control valve of a forging press under severe operating conditions
Abstract
This study aims to improve the stability and performance of control of the moving crosshead in the main hydraulic directional control valve of a 10,000-tf forging press manufactured by Ural Heavy Machinery Plant (UZTM, Russia). The press is used to produce rings of various profiles and materials as part of the ring-rolling process. Typical processes in the main system components were modeled using the TIA Portal software platform. Improved stability and control performance were achieved by developing and implementing specialized algorithms for processing signals from the manual joystick. The algorithms were tested on the actual equipment. A control signal generation algorithm was developed and implemented to limit the rate of signal change to a level sufficient to prevent hydraulic shock and to provide an S-shaped servo-valve flow characteristic through cascaded first-order lag elements, thereby minimizing transients. Testing confirmed that the processing block for joystick input completely eliminates the effect of the nonlinear region while maintaining a stable zero setpoint in the neutral position. The setpoint generation block ensures a smooth change in the servo-valve flow characteristic along an S-shaped trajectory without hydraulic shock. The modernization reduced equipment downtime for repairs by 7 %, confirming the practical effectiveness and economic feasibility of the proposed solutions. The developed algorithms and technical solutions were validated on actual equipment at an industrial facility in the Chelyabinsk Region. Implementation of the control system increased the operational reliability of the hydraulic directional control valve by 5–7 %, eliminated hydraulic shock, and provided accurate positioning with opening and closing times of up to 1.5 s. The proposed solution can be adapted to upgrade the control systems of similar hydraulic presses and other manually operated forging and stamping equipment, thereby extending their service life.