Research On Dynamic Response Characteristic And Speed Control Of Moving Beam Drive System For 300MN Die Forging Hydraulic Press

The 300MN die forging hydraulic press is key equipment of national defence and foundation construction of our country.Its moving beam's drive and control technology is one of its key technology.The flow of the beam's driving system is giant.The load and deformation of working house's system are giant.The forging force is continuously varing.A complex coupling relation exists in all kinds of its parameters.The drive and control system is a complex mechanical-electrical-hydraulic coupling system.There are't automation forging system or isothermal forging system in the hydraulic presses presently.The dynamics response characteristic of the driving system is unknown.Transient load,giant inertance,hysteretic control,low control accurancy and low robustness exist in the moving beam's speed control system.Therefore,this paper studied the speed drive and control system of the hydraulic press,based on its control mechanism,dynamic response characteristic and control strategies,to improve speed control accurancy and supply technical base for realization of die forging automation,isothermal forging or simulation isothermal forging.In this paper,these main research works and conclusions as following:(1)Based on analysis of present state and perspectives on the speed control technology of these domestic and foreign giant die forging hydraulic press,and such characteristics as control hysteresis,low robustness and low control accuracy because of giant inertia,transient load,long waterway,"oil control water" control mode was applied.A new control mode of the distributor's spools open gap was applied based on the mode of "hydraulic cylinder+gear and rack machnism+cam machnism+rotary displacement testing device",to control the flow and direction of the waterway distribution system.A double-closed-loops cascade control strategy was put forward that inner loop was used to control cam shaft angle by PID-H_∞control and external loop to control moving beam speed by PFC-(PID-H_∞)control.(2)Based on coercibility,viscosity resistance,leakage of the fluid, and working house system's deformation etc,flow equation of distribution spool,hydraulic tube and fluid cylinder were established, dynamics eqation of moving beam and upper beam were established, during back play stage,forging stage and hoisting stage.These hydraulic-mechanical coupling dynamics models of drive system for the moving beam were first established,and their simulations and tests were done.At the same time,during the forging stage,these dynamic response characteristics of speed and displacement for the moving beam,pressure of the working cylinder,and pressure difference of the distribution spool were simulated.These simulations and tests showed that these models are correct,speed is vibrating under the the transient load,control hysterisis time is 0.7 second,and the control accrancy is influenced.(3)The principle and structure were analysed on hydraulic operation control system of the 300MN die forging hydraulic press.The phenomenon that the transient load existed in the control system was discoverred,and the load was a main factor to influence the control robustness and accrancy.The hydraulic operation control model was established based on the giant transient load.These strategies based on the single PID control and PID-H_∞control were simulated and tested.The research result shows that PID-H_∞control can suppress the influence from the transient load.Based on giant and transient load,a new right cam-lifting curve was put forward which was a linear relation between open gap of spool and cam shaft rotary angle,and based on which target is maxmal pressure angle of the curve,its optimization model was established,simulated and designed.(4)Based on such characteristics as slow response speed,low accuracy and low robustness,a double-closed-loop PFC-(PID-H_∞) cascade speed control system was put forward and designed.Its simulations were done under the mismatched model and the disturbance. The result shows that there are good steady-state accuracy,dynamic characteristic,robustness and traceability in the control system.(5)Based on the main distributor's double-shaft synchronism, multi-channel and large flow,the open diagram of distributor,the structure and volume of the valve body were optimized.A speed control computer control system based on bus technique,multisystem cooperation,many main stations,complex network was put forward. Based on the control principle of proportional flow,the hydraulic operation system was developped.With WINCC configuration software, an upper computer intelligent speed monitoring and controlling system based on topology network structure,multi-window,grading man-machine interface was developped.These systems were originaly integrated.For the first time,the speed control of the 300MN die forging hydraulic press was developped.(6)The test on the PFC-(PID-H_∞)speed control system in 300MN die forging hydraulic press was carried out under different speeds and technical conditions,in order to prove the correctness,reliability and practicability of the application of the control theory,the establishment of the control model and the proposition of control strategy.The result shows that the test results coincide with the theory stimulation results. The test shows that dynamic and static rotary control accuracy of the cam shaft in the distributor is±1°.The static position control accuracy of the distributor spool is±0.2 mm,its dynamic accuracy is±0.5 mm,speed control accuracy is(0.26～1.35)mm/s under different load.