Dynamic Characteristic Analysis And Structure Optimization Of The Main Shaft Of Heavy-Duty High-Precision Inertial Friction Welding Machine

Friction welding(FW)is a pressure welding method that utilizes the heat generated by relative frictional motion between the welding parts to achieve reliable material connection.With the continuous development of friction welding machine tools,Inertia Friction Welding(IFW)technology has been widely applied in the manufacturing of commercial large aircraft engines,which is a key process technology that restricts the development of China’s commercial large aircraft.One of the most important components that affects the performance of the machine tool is the machine tool spindle.To improve the accuracy and stability of the machine tool spindle,it is crucial to study its dynamic and static performance.Additionally,to meet the requirements of shortening analysis time and reducing costs,necessary research is needed in the analysis and optimization system of the spindle.This paper explored the variation law of critical speed and unbalanced response of the heavy-duty high-precision inertia friction welding machine spindle system at different node positions using rotor dynamics theory and optimized its dimensions to reduce costs.The work overview of the spindle in this paper was as follows:(1)To improve analysis efficiency,a method for equivalent concentrated mass modeling of the spindle system was proposed based on the detachable and combinable feature of the inertia flywheel of the IFW machine.By equivalently combining the inertia flywheel into a concentrated mass point and inserting it into the mass model of the spindle system,an equivalent model of the spindle-flywheel system was established.(2)Using the Riccati transfer matrix method,the critical speed of the established concentrated mass model of the spindle system was calculated and analyzed.The effects of bearing stiffness,inertia flywheel combination form,and bearing axial support position on the critical speed of the spindle system were explored.The analysis results showed that the critical speed of the spindle system was proportional to the bearing stiffness and inversely proportional to the mass of the flywheel combination.Additionally,the overhang length of the spindle was one of the key factors that affected the critical speed of the system.The closer the unbalanced mass distribution was to the front end of the spindle,the greater the vibration response of the spindle system at the second-order natural frequency.(3)A finite element model of the spindle system was established for static and dynamic simulation analysis.The analysis results of the equivalent concentrated mass model were compared with those of the finite element model.The results showed that the analysis error of the equivalent concentrated mass model was within 2% compared to the finite element analysis.Compared to the finite element method,which had a more detailed modeling but longer calculation time,the application of the equivalent concentrated model method not only guaranteed accuracy but also reduced calculation time,demonstrating the effectiveness and rationality of the proposed modeling method.(4)A standard second-order response surface model was established using the Optimal Space-Filling Design(OSF)algorithm,and the response surface was optimized using the Multi-Objective Genetic Algorithm(MOGA)algorithm in the Design Exploration module of ANSYS Workbench software.The maximum critical speed of the optimized spindle was increased by 12.22%,the weight was reduced by 13.53%,and the maximum deformation was reduced by 23.75%.The performance of the optimized spindle had been improved to a certain extent,providing a theoretical basis for the design of the IFW machine spindle system.