Research On Dynamic Modeling And Stability Prediction Method Of Spiral Surface Milling System

Because of its excellent pressurization performance,screw pumps and screw drilling tools have been widely used in the petroleum industry.As the core component of screw pumps and screw motors,screw rotors play an important role.Therefore,the machining accuracy of the screw rotor has attracted attention in the industry.Usually,special equipment such as a screw milling machine is used to complete the forming and processing of the rotor.Because of the vibration phenomenon generated in the process of screw rotor machining,the source of vibration is analyzed,combined with the special structure of the special tool,the tool is modal simulation analysis,the main vibration mode of the tool is analyzed,and the modal parameters of the tool are obtained through modal experiments.A three-degree-of-freedom dynamic equation is established,and the Implicit Adams method(IAM)is used to predict the stability of the screw rotor milling process.A linear time-lag differential equation is used to express the milling dynamics model of the influence of regenerative chatter,and the cutter tooth milling cycle is discretized.The dynamic equation is numerically solved,and the Floquet stability criterion is used to judge the stability of the spiral surface milling system and obtain the stable lobe diagram.According to the stability of the lobe diagram,the processing parameters are selected for experiments to verify the applicability of the implicit Adams method in the spiral surface milling system.Firstly,research on the machining mechanism of screw rotor milling,establish a mathematical model of milling force based on instantaneous rigid cutting theory and establish a three-degree-of-freedom dynamic model.Secondly,the dynamic characteristics of the disc milling cutter are analyzed,and the three-dimensional model of the disc milling cutter is established.The modal information and mode shapes of the disc milling cutter were obtained using modal simulation analysis and harmonic response analysis.Then the transfer function curve and coherence curve of the disc milling cutter under assembly condition was obtained by modal experiment to verify the simulation results.The modal parameters are extracted to provide a theoretical basis for further research.Finally,the average milling force coefficient identification method is used to calculate the milling force coefficient,and the milling force coefficient is regressed by the multiple regression method.The linear time-lag differential equation is used to express the milling dynamics model affected by regenerative chatter,and the implicit Adams method is used to solve the model equations.The Floquet theory is used to judge the stability of the system and obtain the stable lobe diagram.The stability lobe diagram verifies the selected milling processing parameters.The controlled variable method is used to explore the influence of modal parameter changes on the stability area.