Stability Analysis And Control During High-speed Milling Of Aerospace Thin-walled Parts

In recent years,with the rapid development of aerospace technology,people have continuously increased the requirements for the maneuverability and structural strength of aircraft and spacecraft.In order to reduce the weight of modern aircraft and spacecraft and improve their overall structural strength and performance,thin-walled integral structural parts have attracted widespread attention.However,due to the complex shape and poor rigidity of the thin-walled structure,the tool / workpiece system is prone to milling chatter during the overall milling process,and the processed workpiece is easily deformed,which in turn has many adverse effects on the surface processing quality of the workpiece and accelerates it.In order to reduce the wear of the milling tool,reduce the service life of the cutting tool,even in severe cases will lead to the scrapping of the milling tool.Therefore,studying the flutter mechanism during high-speed milling and establishing the dynamic model of the milling system are of great significance for analyzing the stability of the thin-walled part during the milling process.The main work of this article is reflected in the following aspects:First,the influence of different cutting parameters on the stability of the milling system was analyzed based on the semi-discrete method.In the milling system,parameters such as cutting parameters(radial depth of cut rate),modal parameters(stiffness,damping ratio and natural frequency),and structural parameters of the tool(number of teeth)are used as variables.On the premise that other parameters are unchanged The stability of the milling system is analyzed and compared.The stability of the milling system under different parameters is obtained through the analysis of MATLAB programming,which provides data support for the parameter selection in the milling process.Secondly,when predicting the flutter stability of the thin-walled workpiece processing system,the influence of material removal on the dynamic characteristics of the workpiece is considered,and a method of obtaining the dynamic parameters of the thin-walled workpiece through structural modification is proposed.This method only needs to perform dynamic modeling on the initial state of the workpiece,and obtain the dynamic model of the workpiece during milling by modifying the initial model structure.It avoids repeated modeling of the workpiece and modal analysis of large-scale equations caused by material removal,thereby improving the work efficiency in predicting the milling stability of thin-walled workpieces.Thirdly,a three-dimensional stability leaflet diagram was established with the tool /workpiece relative position,spindle speed,and axial cutting as coordinates.Based on the method of structural dynamic modification,the system stability of different relative positionsof the cutter / workpiece during the milling of thin-walled parts was predicted,and the two-dimensional and three-dimensional stability leaf maps of the milling system at different relative positions of the cutter / workpiece were obtained.Finally,the magnetorheological damper is used to suppress chatter vibration during milling of thin-walled parts.A magnetorheological damper structure is designed to effectively combine the constrained damping structure and the magnetorheological structure,which can more effectively absorb the vibration generated during the cutting process.The variation of the vibration displacement of the workpiece with / without magnetorheological damper is analyzed through simulation.A semi-discrete method is used to establish a comparison chart of the stability limit of a process with / without magnetorheological damping.Through analysis,it was found that the milling processing system with magnetorheological damper can effectively suppress milling chatter.The research in this paper provides basic research ideas and methods for the analysis and control of the stability of aerospace thin-walled parts during milling.In order to optimize the milling process of thin-walled parts,the appropriate cutting parameters are used to improve the accuracy of the milling system and the overall production efficiency.