Optimum Design And Dynamic Characteristic Analysis Of Six-Bar Main Drive Mechanism Of 8000kN Warm Forging Servo Press

The birth of warm forging servo press provides a new processing technology for equipment manufacturing industry.It not only has the advantages of high material utilization and production efficiency,good processing quality and large slider stroke,but also obtains different motion curves by changing the output program of servo motor to meet different processing technology and achieve the purpose of flexible production.The research of main drive mechanism has always been the difficulty and key point in the design of warm forging servo press.In this paper,the six-bar main drive mechanism with center arrangement of crank and slider for 8000 kN warm forging servo press was taken as the research object,and its kinematic and dynamic characteristics were mainly analyzed.The specific research contents are as follows.(1)Kinematics formula derivation of six-bar main drive mechanism with center arrangement of crank and slider for 8000 kN warm forging servo press and creation of man-machine interface.Aiming at the six-bar main drive mechanism,the kinematics mathematical model was established by using vector complex method,and the kinematics expressions of the slider and the hinge points of the rod were derived.Then,according to the user's requirements,the kinematics man-machine interface of the sixbar main drive mechanism was created by using MATLAB software.(2)Parameter optimization of six-bar main drive mechanism of warm forging servo press.According to the characteristics of warm forging process and considering the cost of products,the objective function of minimize the output torque of crank,the speed,the acceleration of slider in forging stage and the "product economy" were determined.The conditions of crank existence,the angle and swing angle of upper connecting rod,the lateral force of lower dead point and the stroke of slider were the constraints.The multi-objective parameter optimization mathematical model was constructed by using hierarchical sequence method and genetic algorithm,and the optimized parameters were obtained by solving and calculating with MATLAB software.(3)Dynamic characteristic analysis of six-bar main drive mechanism of warm forging servo press.The dynamic static equation of the six-bar main drive mechanism was constructed by using Darumbell's principle,and the dynamic static analysis was carried out.The force changing trend of each hinge point of the six-bar main drive mechanism under no-load and load conditions and the output characteristics of crank torque were explored.It was concluded that the force situation in the return stage under no-load condition was more complex than that in the push stage,and the maximum force occurs in the return stage.Under load condition,the dynamic characteristics of six-bar main drive mechanism were mainly affected by load.And the influence of gravity,inertia force and inertia moment of the rod could be neglected.The first six modes and natural frequencies of the six-bar main drive mechanism were obtained by modal analysis with finite element software,and the rigidity of the three joints of crank and angle bracket was poor.The six-bar main drive mechanism will not produce resonance phenomenon in practical work.(4)Virtual prototype simulation and load capacity test of six-bar main drive mechanism of warm forging servo press.In kinematics simulation,the angle frame and slider were taken as the research object,and the influence of the motion law of the three hinge points of the angle frame on the motion characteristics of the slider was analyzed.It was concluded that the motion of the hinge points of the angle frame and the upper connecting rod mainly play a role in regulating the speed of the slider,and the motion of the hinge points of the angle frame and the lower connecting rod mainly plays a role in transmitting the motion.In dynamics simulation,the crank and slider were taken as the research object,and the base was obtained.Based on Hertz contact theory,the influence of clearance collision force on the dynamic characteristics of six-bar main drive mechanism was analyzed.It was concluded that clearance collision force has a great influence on the mechanical characteristics of space travel stage.Under load condition,clearance collision force has a relatively large impact on the mechanical characteristics of horizontal direction,but a relatively small impact on vertical direction.Finally,the load of warm forging servo press was tested by a digital load tester.The conclusion was drawn that the load capacity basically meets the design requirements.