| The tool edge preparation process,when administered properly,adds strength to the tool cutting edge,lengthens usable tool life,minimizes the propensity of the edge to chip,improves part quality and consistency,enhances work piece surface finish,and it heavily influences tool reliability and performance.Accordingly,the tool edge preparation technology has got extensive attention at home and abroad.several edge preparation technologies have been developed,an issue with the aforementioned processes is the significant inherent variability in the geometry of the generated edge,Further to problems with process control,mechanical edge preparation methods are somewhat limited in terms of their application to tool materials such as cemented carbide on account of their extreme hardness and toughness.In this context,the research detailed in this paper presents the proof-of-principle of the novel application of abrasive water jet machining for precision edge preparation of cutting tools.The correction theory of the novel application of abrasive water jet machining is analysis;the performance of edge preparation of cemented carbide with abrasive water jet is studied by experiments.The manufacturing processes and the operating characteristic are developed for cutting edge preparation by AWJM.Based on the theory of abrasive water jet,the mechanism for edge preparation of abrasive water jet machining was studied in detail.A mechanic model of edge material impacted by abrasive jet has been set up;material removal models of erosion by single abrasive particle are established.Theoretical study shows that in certain range of jet pressure,if contact shear stress of abrasive particles impacted is high enough,once upon exceeds the shear strength of the blade,the blade material fall off from parent.When cemented carbides are subjected to particles carried in a high water jet,the results suggested that erosion follows a rule of mixture;the erosion of the WC phase occurring by a Hertzian elastic fracture mechanism,and that of the Co phase by combined cutting and deformation mechanisms.When cemented carbide materials impacted by solid particle,fracture and ductile erosion occurs simultaneously.For the WC phase,the material is removed by brittle fractures,but for the Co phase,the material is removed by ductile erosion.By using design of experiment(DOE),the influence of the process parameters on the quantity of removed material and the characteristics of the surface of the cutting tool was observed.Aspect as radius of the cutting edge,chipping of the cutting edge,and microstructure of the cutting tool surfaces were considered for abrasive water jet process.Experimental investigations to observe the influence of flux and particle diameter of abrasive,water jet pressure,stand-off distance,and jet feed speed on the generated cutting edge radius and theroughness of the tool surfaces were carried out for cemented carbide cutting tools.The study shows that a notorious increase of the radius generated was observed by increasing the jet pressure,these behavior has nearly linear tendency.On the other hand,for the considered range of pressures,the roughness increases with the increase of pressures;an optimal value exists for the abrasive flux,the edge radius grows with the abrasive flux in certain range,then decreases when the flux over the optimal value;a decrease of the size of the abrasive particles,produces a decrease in the radius of the prepared cutting edge,these behavior has non linear tendency,Regarding the roughness,the decrease in particles size generates a decrease in the roughness,and the tendency is non linear too,and additionally the quality of the surface improves by using small grain size of abrasive.The edge radius decays with an increase of the jet feed.An optimal value exists for the stand-off distance,results that of more significance.This paper is focused on AWJM,through processing the study on the whole design of abrasive water jet machining device used for edge preparation.The structure of device includes the intensifier,the accumulator,and the system of abrasive feed,the parts of the NC workbench,the cutting head,and the parts of adjusting nozzle.The processes and the operating characteristic are developed for cutting edge preparation by AWJM. |
