Study On Passivation Of Cemented Carbide Tools By Gas-solid Two-phase Abrasive Flow

The micro-defects such as irregular notch,indentation and pits at the tool edge are unavoidable in the process of tool grinding.For the tool itself,these defects will become the source of stress concentration in the process of metal cutting.Under the action of cutting force,it is easy to diffuse and produce cracks,which seriously affects the service life of the tool and the reliability of the tool.For the workpiece to be cut,these microscopic defects,especially the residual marks on the flank of the grinding tool,increase the compressive stress on the flank and the surface of the workpiece to be cut,aggravate the tool wear,and seriously affect the surface quality of the workpiece.In order to weaken or even eliminate these irregular defects,the tool was passivated.After passivation,the micro defects are improved and the irregular edge is changed from sharp to regular edge with a certain regular blunt radius,which greatly improves the strength of the edge.The extension of tool life and the improvement of workpiece surface quality meet the requirements of high speed,high precision and ultra precision metal cutting.In this paper,the passivation of tool edge by gas-solid two-phase abrasive flow was studied.Based on the particle dynamics theory and discrete element theory of gas-solid twophase flow,the EDEM-FLUENT coupling method was used to study the influence of inlet velocity,radius ratio,forward and reverse time ratio,abrasive particle size and abrasive sphericity on abrasive flow state,blade impact number,blade force and wear amount by numerical simulation system.The tool passivation experiment platform based on gas-solid two-phase flow abrasive particles was built.The orthogonal experiment was used to study the influence of passivation time,positive and negative time ratio,inlet pressure,radius ratio and rotating speed ratio on the passivation value of the front tool surface S?,the passivation value of the rear tool surface S? and the shape factor K when the tool asymmetric edge shape factor K<1 and K>1.Based on the energy absorption theory,the material removal model of single abrasive particle was established,and the mathematical model of asymmetric cutting edge of tool passivation was established according to the swept volume of tool positive and negative.By combining with the passivation experiment,the feasibility of the mathematical model of asymmetric cutting edge was verified,and the formation mechanism of asymmetric cutting edge of tool passivation was revealed.