Study On Cutting Tool Material Compatibility Of Alloy Cast Iron For Diesel Engine Cylinder Block

As an important power source in the fields of automobile,ship,diesel locomotive,engineering machinery,military equipment and so on,the development of diesel engine plays a key role in the industrial progress,economic development and national defense construction.Compared with the gasoline engine,diesel engine has the characteristics of durability,energy saving,economy and environmental protection.By means of the addition of Cu,Cr,Sn,the mechanical properties and casting properties of alloy cast iron for cylinder block of WP10 diesel engine have been improved obviously.However,the addition of alloying elements also reduces the machinability of alloy cast iron,resulting in serious tool wear,which affects the machining efficiency and machining cost.Reasonable matching of the cutting tool material(including coating material)can effectively improve tool life,machining cost,machining efficiency.In this paper,the tool matching of alloy cast iron for cylinder block of diesel engine is studied,the main research contents are shown as following:(1)The chemical,physical and mechanical properties of alloy cast iron and cemented carbide is studied by means of diffusion test.Based on the matching of chemical properties,there are obvious element diffusion phenomena between the alloy cast iron and YG cemented carbide cutting tool materials at high temperature.It can be proved from the experiment that Fe in the alloy cast iron diffused a deeper distance with higher Co content of WC/Co cemented carbides and the diffusion of W element in the WC/Co cemented carbides the alloy cast iron was lighter.Based on the matching of physical and mechanical properties,YG6X.YG6A is suitable for finishing machining,semi finishing machining because of high hardness and balanced other performance indicators;YG8 is suitable for rough machining because of high impact toughness and bending strength.(2)The matching of alloy cast iron and coated cemented carbide tool is studied by means of diffusion test,oxidation test and cutting test.The result of high temperature diffusion experiments shows that diffusion between the CVD(TiCN)composite coating cemented carbide with alumina membrane and alloy cast iron is little and the diffusion inside tool only occurs at high temperature,therefore its diffusion resistance is outstanding.Diffusion between the PCVD(TiN),PVD(TiAIN)coating cemented carbide with alumina membrane and alloy cast iron is obvious and the diffusion inside tool occurs at lower temperature,therefore its diffusion resistance is bad.The cutting experiment results show that the wear rate of the cutting tool is smaller and the surface roughness of F40M((Ti,Al)N-Ti(C,N)-TiN)is lower than MK1500(Ti(C,N)-Al2O3),but it wear faster in the early stages of cutting and edge gap emerged.(3)The fracture morphology and mechanism of coated carbide tools in milling of alloy cast iron were analyzed.The main type of tool wear morphology is chipping,coating breakage,exfoliation,micro-extrusion,abrasive wear,adhesive wear and diffusion wear.This study have guide meaning to tool matrix and coating material selection of the manufacturing of alloy cast iron for diesel engine cylinder block.