Optimized Design Of Eight-bar Linkage Press Mechanism

With the rapid development of the automotive industry in recent years,the requir ements for mechanical press performance are also getting higher and higher.When a t raditional crank press is used to stamp a large thin-walled cover,it will be damaged d ue to high stamping speed or excessive fluctuation of drawing speed.In order to solve this problem,an eight-bar linkage mechanism was optimized and designed in this arti cle,which was combined with the actual project.Firstly,press overall structure plan was analysed,the rod parameters of the nominal pressure 25000kN press were obtained by the analogy method,to get the kinematics o f the slider of the eight-bar linkage mechanism,the kinematics equations of the mechan ism were established,and the displacement,velocity and acceleration equations of the sli der were obtained.The slider displacement,velocity,acceleration curves were drew by M ATLAB.The advantages and shortcomings of mechanism were analysed by the motion curve analysis.Secondly,compared with the previous genetic algorithm,a genetic algorithm with g ood convergence and strong global search ability was proposed.Then parameters of the mechanism were regarded as the design variables,the possible constraints were tapped,reducing the standard deviation(STDEV)of speed in the drawing stroke was regardedas the optimization target,the improved genetic algorithm was used to optimize this p roblems.After optimization,the STDEV of deep-drawing speed decreased from 100.5822 mm/s to 84.0684mm/s,and the maximum speed decreased from 488.8691mm/s to 423.0235mm/s.Thirdly,through the three-dimensional modeling of the bars,the quality of the bars,t he centroid position and the moment of inertia were analysed.The movement law of t he mass center was gave by the kinematic analysis of the mass center.To establish the matrix equation of dynamic statics,through the analysis of dynamic statics about linka ge,inertial force and moment were took into the equation of force balance by the fron t analysis.According to the 25000kN's nominal pressure,the maximum crank torque wa s calculated by the matrix equation of dynamic statics,and then the mechanism's stamp ing capacity curve was obtained,the press drawing capacity was verified.According to t he bars' quality,the total weight of the mechanism was calculated,the balance cylinderpressure value was got by he total weight of the mechanism.Finally,to develop the fast optimization system,the system's functions were analys ed,and system functions' flow,interactive interface,control response programs were d esigned.After that,a example was applied to verify the implementation of system functi ons,software running speed was optimized.