Dynamics Analysis Of The Parallel Linkage Forging Manipulator

The design and manufacturing level of large forgings is a concentrated reflection of a country’s industrial level,and the manufacturing of large forgings depends on the ability and level of heavy-duty manufacturing equipment represented by forging manipulators.As an important basic equipment for forging mechanization and automation,the core technology of forging manipulator design is still relatively dependent on foreign countries.The backwardness of heavy-duty manufacturing equipment has seriously restricted the manufacturing capacity and production efficiency of large forgings in China.Thus,it is of great significance to vigorously carry out research on the basic science and key technology of forging manipulator to improve the manufacturing level of large equipment in China.This paper closely focuses on the dynamics performance of the heavy-duty operating machine and the stability and safety of the braking conditions,and carries out the dynamics analysis of the operating machine to provide theoretical support and reference for the design of the buffer device of the parallel-linked forging manipulator.The main research works are as follows:Firstly,the physical model of forging manipulator dynamics has been established.In order to establish a physical model of dynamics that can truly reflect the interaction law of “forceposition” and “machine-hydraulic”,a study was conducted on the relationship between the forging process and the hanging system.The correlation between the forging process and the cushioning mechanism of the hanging system was studied.By establishing the inverse kinematic model of the operator under forging conditions,the influence of the press down and workpiece elongation on the operator during the forging process is clarified based on the process parameters of a typical forging process,the working mechanism of the passive compliance of the hanging system is determined,the design ideas of the buffer cylinder and associated structure of the hanging system are proposed,and the “full load and strong impact”single buffer system and double buffer system are simplified and established.Secondly,the action law of "mechanical structure-hydraulic device" on the dynamic stability of the operating mechanism was clarified.The kinetic equations of the single buffer system were established based on the Newton-Euler method,and the proxy model of nonlinear stiffness was obtained by quadratic curve fitting considering the nonlinear characteristics of buffer stiffness and damping;the multi-objective optimization of nonlinear buffer damping and accumulator initial inflation pressure was realized based on NSGA II,and the effects of constant and nonlinear buffer stiffness and damping on the braking stability of the system were compared and analyzed.The results show that considering the nonlinear stiffness effect of the accumulator,the vibration amplitude of the system when subjected to shock load is reduced by3 mm and the vibration convergence time is shortened by 2.5 seconds.Not only the stability of the operating machine is obviously improved,.Effectively solved the problems of nonlinearity and parameter time-variability brought by the hydraulic device also effectively combines and matches the practical application with the parameter design,providing a theoretical basis for the design of the operator’s buffer device.Again,it reveals the action law of the coupling of the double buffer system of the large car walking and hanging.For the coupling model of the double buffer system of the car walking and hanging,the kinetic differential equations are established based on the Lagrangian method,and the influence of the buffer stiffness and damping of the double system on the mechanical performance of the operator is analyzed.The results show that under the limitation of braking accuracy of the car walking system,the buffer stiffness and damping of the car walking in the coupling action of the double buffer system shorten the vibration convergence time of the pincer bar center of mass by 16.67%,no significant change in the amplitude range,but the vibration frequency is reduced by 50% compared with the effect of single-degree-of-freedom constant stiffness and damping.Thus,the coupled dynamics analysis of the double buffer system of carriage walking and hanging is not only closer to the actual working conditions,but also provides a theoretical basis for the design of the buffer device of the operator.Finally,the virtual prototype co-dynamics simulation of the forging operator was realized.After establishing the 3D geometric model of the forging operator,the mechanical subsystem and the hydraulic subsystem models were established based on ADAMS and AMESim respectively,and the data exchange and communication between the multidisciplinary models of the forging operator were realized by using the interface,so that the virtual prototype codynamics simulation model of the forging operator was built.It was verified that there is a positive coupling effect of the buffer between the traveling system of the car and the hanging system,and the initial inflation pressure and volume of the accumulator were determined,which provides theoretical support for the design of the buffer device of the operator.