Trochoidal Milling Stability And Influencing Factors Analysis In Surface Quality Of The Aircraft Landing Gear Cavity

The aircraft landing gear is known for large zize,multi-cavity structure,large material removal rate,and its high surface quality requirement.Adopting new processing techniques has become effective methods for improving surface quality.Trochoidal trajectory can be used to machine cavities.To avoid interference during trochoidal milling,it is necessary to use thin and long tools which cause poor processing system dynamics.The irrationally large trochoidal step usually leads to chatter,while the conservative trochoidal step constrains the machining efficiency.It is necessary to establish a corresponding stability model for predictive analysis,which provides a theoretical basis for optimizing the processing parameters of the landing gear cavity.The landing gear is one of the aerospace hard-to-machine material.The poor cutting performance will seriously affect the surface quality,while reducing the service performance of the entire landing gear.The mininum quantity lubrication(MQL)is used to study and analyze the effects of lubrication conditions and cutting parameters on the surface quality of the cavity machining.It provides the basis for optimizing the processing parameters and improving the surface quality of the landing gear cavity.In this paper,a stability prediction model of trochoidal milling is established to solve the above problems.An approach considering trochoidal steps and spindle speeds is presented to predict stability boundary of trochoidal milling.According to the characteristics of trochoidal milling geometric model,the varying cutter-workpiece engagements are analysed.Based on the lowest envelope of the stability boundary at different tool positions of trochoidal tool path,the limit value of the stability prediction during the trochoidal milling process can be obtained to ensure processing stability.In order to improve processing efficiency,verification experiments of trochoidal tool path stability model are performed on the machining center GMC 1600H/2,and the accuracy of the trochoidal milling stability prediction model is verified.Based on the stability boundary,the optimization strategy of trochoidal step is proposed.The simulation analysis is performed,and simulation results show that the use of an optimized trochoidal step can effectively improve the cavity stable machining efficiency of the trochoidal milling.Considering the service performance of the landing gear,MQL is used to conduct comparative analysis experiments.The effects of machining lubrication conditions(dry cutting,MQL)and cutting parameters on the surface quality(surface roughness,surface residual stress,microhardness)of the cavity processing are studied and analyzed,so as to optimize the machining parameters and improve the quality of the machined surface of the workpiece.Based on the trochoidal milling theory of the cavity and the MQL process,the theoretical and experimental results of both are applied to the actual processing of the aircraft landing gear cavity.In this way,the machining stability and surface quality of the landing gear cavity can be improved in the actual processing conditions.