| The coating can improve the cutting performance and wear of the tool,prolong the service life of the tool,it can also improve the quality and positional accuracy of the machined surface quality of the workpiece.Therefore,it has been widely used in various fields of metal cutting.In this article,we based the Layer development and application of coated tools,design and make the TiN/MoN,TiAlN/MoN,TiAlN coating by Closed Field Unbalanced Magnetron Sputtering Ion Plating(CFUMSIP)equipment with the aim of improving tool hardness and reducing tool-chip and tool-workpiece friction coefficient,.These nano-gradient composite structure coating was studied on the drilling process of 304 stainless steel,a difficult-to-machine material.The drilling force,torque and temperature change,tool wear law and failure characteristics of uncoated and coated tools were analyzed to explore the coating.We aim to explore the modified effect of the twist drill processing and the failure mechanism of the designed coated tool,comprehensively evaluated the drilling performance of the coated cutter when cutting difficult-to-machining materials.Firstly,the properties of three kind of coating were measured.The composition and microstructure of the coating were observed by X-ray diffractometry and Scanning Electron Microscopy(SEM).The mechanical properties of the coating were measured using a nanoindentation machine,friction were measured using Friction and wear tester.The effects of different coating structures and different elements on their mechanical properties,friction and wear charactristic were analyzed,and then TiN/MoN and TiAlN/MoN coatings were selected.Secondly,using metal cutting principle and finite element theory,combined with Advant Edge simulation,a three-dimensional drilling model of 304 stainless steel was established.The analyzed results showed that the chisel edge and outer edge corner of the tool subjected to the highest temperature and stress,the coating can reduce the temperature in the tool-chip contact area,it can also reduce cutting force and torque of the tool effectively,as a result,the plastic deformation of the tool be reduced;The application of simulation methods can intuitively observe the stress and temperature during drilling.;for TiN/MoN and TiAlN/MoN coated twist drills The influence of coating thickness and cutting parameters on the cutting performance was studied,the optimal coating,optimal thickness and optimum processing parameter range of the theory during drilling were given.Finally,the wear mechanism was studied.It was found that when the coatings were thin,they did not play a good role in improving the tool life.When drilling the 304 stainless steel,the uncoated tools had wear failures after almost no stable wear stages,while the coated tool showed excellent wear resistance characteristic,and the wear phase of the TiN/MoN coating was longer;the coating can suppress both the rake and flank wear effectively,the sticking of the workpiece was also improved.The fine columnar structure and nano-multilayered gradient structure,low thermal conductivity and small friction coefficient greatly improve the cutting performance of the coating in the anti-abrasive and oxidative wear properties,which makes the coated tool show excellent cutting performance and longer service life. |
PDF Full Text Request