| 300M ultra-high strength steel(40CrNi2Si2 MoVA)is a landing gear steel with excellent comprehensive mechanical properties(high strength,high toughness,etc.),which is a typical aviation hard to process material,which contains a large number of Ni elements(1.65%-2.0%),and the thermal conductivity of the material(21.6 w/(m·?)is reduced when the rigidity and hardness of the materials are increased(52HRC).Under the complex thermal stress field in the actual cutting process,the surface integrity of 300 M ultra-high strength steel is difficult to be effectively controlled.The special use of aviation parts determines that the surface integrity index such as surface roughness and residual stress is high,and the complex service environment of aircraft landing gear can cause safety accidents due to any surface defects.The outstanding surface integrity of processed surface is an important guarantee for the excellent safety performance of landing gear.The mechanical properties,high speed milling technology and optimization of 300 M ultra-high strength steel are studied in depth.Firstly,the dynamic mechanical properties of 300 M ultra-high strength steel are investigated by SHPB test device,the sensitivity of 300 M ultra-high strength steel to the main influencing factors of flow stress is studied,and the plastic deformation behavior of SHPB samples at high temperature is analyzed;the J-C constitutive equation parameters of 300 M ultra-high strength steel are determined by static and dynamic compression test data,and the JC constitutive equation parameters of 300 M ultra-high strength steel are determined based on orthogonal design The cutting test data and optimization algorithm optimize the constitutive model parameters,obtain J-C constitutive equation suitable for the actual high strain rate milling.Based on the J-C constitutive equation,the milling process of 300 m ultra-high strength steel is verified by numerical simulation,and the simulation accuracy is greatly improved.Secondly,orthogonal and single factor experiments were designed to explore the cutting force variation of 300 M ultra-high strength steel under different milling parameters by milling and finite element simulation.Based on the Oxley analytical machining prediction theory,the model of Zhuzhou Diamond FMR01-040-XP32-RC12-03 cutter was established,and the milling force simulation was carried out;the box Behnken ring was designed Based on the milling test data,the regression models of cutting force and cutting temperature of 300 M ultrahigh strength steel were established and tested.In addition,the wear patterns and wear mechanism of 300 M ultra-high strength steel milling by carbide cutters of different brands and models such as Zhuzhou Diamond,yamagao and Sumitomo are analyzed by using the help of the ultra-field microscope and energy spectrometer.The influence of different wear stages and states on the material quantity(cutting force,cutting temperature,etc.)in the milling process is studied.The surface roughness,surface morphology,micro hardness are used to analyze the wear patterns and wear mechanism of300 M ultra-high strength steel As the evaluation index of surface integrity,the surface integrity of 300 M ultra-high strength steel under different milling conditions is studied by single factor and orthogonal test.Finally,based on the milling test data of 300 M ultra-high strength steel,GA-BP neural network model of cutting force and surface roughness is established,and the prediction accuracy of different models is compared and tested.In order to realize the high efficiency and high quality milling of 300 M ultra-high strength steel,the surface integrity(surface roughness)and processing efficiency(material removal rate)are optimized,and the multi-objective particle swarm optimization is adopted The optimization algorithm optimizes the milling process,obtains the combination of cutting parameters suitable for the actual cutting conditions,and the surface integrity is improved significantly by experiments. |
PDF Full Text Request