Study On The Machined Surface Quality In High Speed Turning 300M Steel Under Cryogenic Minimum Quantity Lubrication

With the development of technology,high speed cutting difficult-to-machine materials has become one of the hot spots in manufacturing industry.300 M steel has long been used in the manufacture of aircraft structural parts due to its high strength and high hardness.However,as a difficult-to-machine materials,its own characteristics make its cutting performance poor,which seriously affects the cutting efficiency and the quality of the machined surface.Traditional cutting methods not only cause waste of resources,but also bring environmental pollution and other problems.Therefore,this paper proposes to apply cryogenic minimum quantity lubrication technology to high speed cutting difficult-to-machine materials,which can effectively improve cutting environment,reduce cutting force,improve processed surfaces quality and avoid environmental pollution,and provides a theoretical basis for the application of cryogenic minimum quantity lubrication technology in actual machining.In this paper,firstly,the single-factor test of high speed turning 300 M steel under cryogenic minimum quantity lubrication environment is carried out.According to the test data,the tool geometry parameters and lubrication parameters are optimized,and the variation law of surface roughness with tool geometry parameters and process parameters are analyzed;According to the optimization results,the three-factor four-level orthogonal test under cryogenic minimum quantity lubrication environment is carried out,and the influence law of cutting parameters on surface roughness is obtained by the range method;The mathematical model of surface roughness is established and the significance of the model is tested.The results show that the mathematical model of surface roughness has a good predictive power.Secondly,the single comparison factor test of surface roughness and surface microstructure under dry and cryogenic minimum quantity lubrication environment is carried out to analyze the influence law and reasons of cutting environment and cutting parameters on surface roughness and surface microstructure;The influence law and reason of process parameters on surface microstructure under cryogenic minimum quantity lubrication condition is analyzed.Thirdly,the microhardness tester is used to measure the microhardness value of the specimen along the working depth direction,and the influence under dry and cryogenic minimum quantity lubrication on the work hardening of the specimen is analyzed;In the cryogenic minimum quantity lubrication environment,the influence of cutting parameters and lubrication parameters on work hardening is obtained.Finally,the residual stress value of the machined surface is obtained by X-ray stress meter,and the variation law and cause of surface residual stress with cutting environment,cutting parameters and lubrication parameters are analyzed;The finite element simulation software DEFORM-3D is used to simulate the 300 M steel turning process and the residual stress along working depth is analyzed.The residual stress simulation value is verified and the cause is analyzed.