Simulation And Experimental Research In Meso-scale Machining Process Of C45 Steel

With the feed rate decrease to the dimension of grain size and tool edge radius, and cutting process is often carried out in the grain interior and grain boundary. According to the examination of the microstructure of the work piece, the hot-rolled C45 is primarily a mixture of 60% vol. pearlite and 40% vol. ferrite phases which is suitable for modeling and simulation. Considering the limitations of continuum mechanics in macro-cutting when used for modeling and simulation in meso-cutting, the method to establish multiphase models are studied in this paper. Combining with the metallographic microstructure analysis of hotrolled C45 steel, several microstructure-based models are built up for the orthogonal cutting processes of hot-rolled C45. And the simulation models are compared with the orthogonal cutting experiments in terms of cutting force.The main contents are as follows:1. Key technologies for finite element simulation are elaborated and are used in the following modeling and simulations. The metallographic microstructure of hot-rolled C45 steel are analyzed. Multiphase geometric models including rectangular grain, Voronoi grain, real grain, are established based on the metallographic microstructure. At the same time, the problems are described during establishing the geometric modeling process.2. Modeling methods and theories used in this paper are introduced. Material constitutive model establishment, choice of chip separation criterion and friction model, meshing technology are also explained. Combining with the geometric models established in previous, five simulation models including equivalent homogeneous material model with rounded-edge cutting insert(Model I), rectangular grain model with sharp edge cutting insert(Model II), rectangular grain model with rounded-edge cutting insert(Model III), Voronoi grain model(Model IV) and real grain model(Model V) are also developed to investigate the effect of rounded-edge cutting insert, material microstructure and grain shape on cutting force.3. In order to prove the reliability of the simulations, the single-factor orthogonal cutting experiments are used to verify the simulation results. Cutting force measurement plan, BUE observation plan and chip observation plan are determined. Cutting force and chip are analyzed to investigate the effect of feed rate and cutting speed on cutting force and chip. Cutting force in simulations and cutting force in experiments are compared to verify the simulation results.4. Combining with the results of the simulation model calculations, five groups of models of cutting force, the stress and temperature fields are compared and analyzed. Five sets of models are compared to investigate the effect of rounded-edge cutting insert, material microstructure and grain shape on cutting force. Combining with the simulation models, stress field and temperature field are analyzed.