Research On Accurate Tracking Control Strategy Of Sliding Trajectory For Servo Press

The press is driven by a motor.The working mechanism of the press converts the torque of the motor into the acceleration of the punching slider and completes the stamping of the workpiece.For the traditional press,the ordinary three-phase motor provide power to drive the slider.As the output characteristics of ordinary motor is not adjustable,the working mechanism of the press once is determined,the trajectory of the lower slider is fixed,which caused the press cannot adjust the trajectory of the slider based on different processing technology.With the continuous updating and development of science and technology,it is possible to control the servo motor speed,torque precisely through the microelectronic control technology.This allows the press to control the trajectory of the lower slider according to the requirements of the different forming processes.Therefore,this paper carries on the simulation research and the experimental verification to the multi-link working mechanism,the acceleration and deceleration curve optimization control,the trajectory error control algorithm and the control system experiment platform development from the point of view of the slider trajectory control.The main contents of the thesis are as follows:1.The research status of servo press at home and abroad is introduced from the aspects of machine development,working mechanism,control system and control strategy.2.The kinematics and dynamics for the new multi-link working mechanism are analyzed,thus,the drive equation of crankshaft torque is established.According to the torque load in the processing,the crankshaft torque curve is acquired.3.The typical stamping process of the press is analyzed to develop the control strategy of the servo system adopting a five-step acceleration and deceleration motion control algorithm.Based on the control optimization algorithm,the typical processing curve is optimized.In order to improve the accuracy of the trajectory tracking control,the PID feedback and the sliding mode variable structure control are used to adjust the error.4.According to the practical needs of the servo press control system,the experimental platform of the servo press system of is designed using the virtual instrument technology which is composed mainly by the following two aspects:(1)Hardware:electrical cabinet design,motion control design,location detection,data acquisition and signal conversion modules.(2)Software:data acquisition procedures,data output procedures,system initialization procedures and experimental platform control interface.5.Based on the control strategy and control method,the trajectory of the slider is simulated with the acceleration and deceleration optimization as variable,and the error of slider trajectory is reduced obviously by the acceleration and deceleration algorithm.By the analysis of the motion trajectory and the vibration acceleration of the lower slider,the author find that the control effect of SMC is better than PID algorithms,and the experiment prove that the acceleration and deceleration algorithm can effectively reduce the vibration of the bed.According to the analysis of the signal from the sensor,PID control algorithm effectively reduce the error of slider trajectory compared with SMC algorithm.