Investigation On Processing Mechanism And Control Of Residual Stress In CMQL Machining

The residual stress on the machined surface is an important indicator of the surface quality of machined parts.Residual stress has a serious impact on the static strength,fatigue strength,corrosion resistance,and dimensional stability of the part,ultimately affecting the working life of the part.With the rapid development of green manufacturing technology,the use of green cooling lubrication technology to obtain a better quality of the machined surface,to achieve control and prediction of residual stress on the surface of the part has become an important research topic in the field of green manufacturing,and its research results to improve the quality of equipment And reliability is of great significance.Cryogenic Minimum Quantity Lubrication(abbreviated as CMQL)is a green cooling lubrication technology that combines low temperature technology and Minimum Quantity Lubrication(MQL).CMQL cutting,because of its low-temperature medium can be quickly forced cooling the surface of the material being processed,on the one hand can reduce the temperature of the workpiece cutting area,the workpiece material brittleness increases,reducing the plastic deformation during cutting;on the other hand will be formed in the material surface layer that the prestress field with cooling shrinkage is as its main feature,which superimposes nonlinearly with the stress field formed by the force and heat during the cutting process,suppresses the generation of residual tensile stress,or leads to the generation of residual compressive stress.This is also the advantage of the CMQL cutting on controlling residual stress.Based on the thermal-mechanical coupling theory of residual stress formation,the CMQL cutting residual stress is taken as the research object.Based on the analysis of the cooling lubrication mechanism of CMQL,the cutting force,cutting temperature and machining surface quality in the CMQL cutting process are studied through experiments.Degree,surface topography,and microstructural and micro-hardness and surface residual stress characteristics change,to explore CMQL cutting mechanism;through CMQL process parameters(medium temperature,injection method),cutting parameters(cutting speed,feed,depth of cut)The effect of blunt circle radius on cutting residual stress was studied.The residual stress of CMQL was investigated and the distribution law was established.The prediction model of residual stress on cutting surface of CMQL was established.The residual stress of CMQL was modeled by finite element and the CMQL was simulated and analyzed.The influence law of cutting residual stress;innovatively proposed the concept of tension-compression stress transition critical temperature of residual stress on the cutting surface,theoretically derived the critical temperature calculation formula.A compounding method of cutting residual stress in CMQL was proposed.By adjusting the temperature of CMQL medium and changing the radius of the radius of the tip,a composite process combining the residual stress of cutting surface of CMQL to the residual compressive stress can be realized.The research on improving the fatigue strength of workpieces has expanded a new idea.