Theoretical Model And Experimental Study Of Residual Stress In Nano-Fluid Micro-Lubrication Grinding Of Cemented Carbide

Green sustainable development is the mainstream trend of manufacturing industry nowadays.In order to solve the problems of high cost,waste of resources and environmental pollution in traditional manufacturing industry,Made in China 2025 puts forward the requirement of cleaner production and sustainable manufacturing in manufacturing industry.The 13 th Five-Year Plan and the transformation of new and old kinetic energy in Shandong Province both put forward the concept of technological innovation and green low carbon.Grinding is an indispensable processing method in mechanical processing.Dry grinding is the earliest and most widely used green processing method in the development of grinding.However,due to the lack of grinding fluid,high temperature often occurs,resulting in thermal damage to the workpiece surface.Reasonable grinding conditions can make the workpiece surface have large residual compressive stress,which can effectively improve the fatigue strength of the workpiece,while high temperature under dry grinding conditions often reduces the residual compressive stress on the workpiece surface.According to the above problems,the theoretical model and experimental study of residual stress in nano-fluid Micro-lubrication grinding of cemented carbide were carried out.The prediction model of surface grinding temperature field under different working conditions was established and simulated numerically,and the validation test of the prediction model was further carried out.In order to predict the residual stress on the workpiece surface more accurately,the load of grinding process is systematically studied and analyzed.The theoretical models of mechanical load and thermal load are established respectively for different forms of application,and the thermal load model of grinding process is simulated numerically.Based on the theoretical model of mechanical load and thermal load,the theoretical model of residual stress is established based on the coupled effect of mechanical and thermal loads,and the theoretical model of residual stress is simulated numerically.Finally,the specific sliding grinding force,the specific friction coefficient and the grinding temperature are taken as the evaluation parameters to evaluate the cooling and lubrication performance under four different working conditions.Specific research work is as follows:(1)The prediction model of the temperature field in plane grinding is established.The numerical simulation of the temperature field in plane grinding is carried out based on the finite difference method of discrete mathematics.The variation law of grinding temperature is analyzed from four angles: cooling condition,grinding depth,grinding wheel speed and workpiece feed speed.The distribution law of grinding temperature field is studied by taking nano-fluid Micro-lubrication condition as an example.(2)Four different cooling conditions were adopted to study the temperature field of grinding cemented carbide,verify the prediction model of plane grinding temperature field,collect grinding force,grinding temperature and surface morphology of grinding wheel in the experiment process,and evaluate the cooling lubrication performance of four different working conditions with specific grinding force,energy proportionality coefficient of incoming workpiece and grinding wheel wear degree as evaluation parameters.The comparison between the simulated temperature curve and the measured temperature curve proves the accuracy of the temperature field prediction model,and also proves the feasibility of grinding cemented carbide under nano-fluid Micro-lubrication condition.(3)Based on the conical abrasive,the cutting force model of a single abrasive is established.Combining with the number of effective abrasive particles on the surface of the grinding wheel,the total cutting force model in the grinding process can be obtained,and the total sliding friction model can be obtained by combining the effect of the grinding force.Because the grinding distribution on the grinding wheel surface conforms to the normal distribution law,the distribution law of abrasive particles on the grinding wheel surface can be obtained.Since the mechanical load on the workpiece surface mainly comes from the normal cutting force of each abrasive particle,the distribution model of the mechanical load on the grinding wheel surface can be determined by combining the cutting force model of single abrasive particle.According to the stress-strain law of material and the constitutive relation of material,the thermal load model in grinding process can be obtained.The thermal load model in grinding process is simulated numerically.The distribution of thermal stress is analyzed from three directions of X,Y and Z of workpiece surface,and the variation of stress with temperature is also analyzed.(4)According to the loading and releasing law of mechanical load and thermal load,the theoretical model of residual stress in grinding process is established,and the theoretical model of plane grinding is simulated numerically.The surface residual stress under different cooling conditions,different grinding wheel speed and different workpiece feed speed is analyzed from the X and Y directions of workpiece surface.Distribution of residual stress at different depths from the workpiece surface.(5)Planar grinding experiments of cemented carbide under four different working conditions were carried out.The grinding force and temperature during grinding and the residual stress on the surface of the workpiece after grinding were collected.Through analysis,the specific sliding grinding force and friction coefficient were obtained,and the cooling and lubrication effects under different working conditions were evaluated.The accuracy of the surface residual stress model and the advantages of nano-fluid Micro-lubrication grinding of cemented carbide are verified.