Research On Tool Wear Process And The Effects On Machining Process In Micro Milling

The tool worn rapidly in micro milling and the tool wear patterns are different from the conventional milling.In micro milling,tool wear can influence the cutting force,chatter stability and the quality of product.In this paper,the tool wear process of micro milling and its effects on machining process have been investigated.The contents of this paper include:(1)The current research status of tool wear,cutting force,chatter stability and burr formation in micro milling are introduced.In micro milling,the rapid wear of tool is the main problem that restricts the widespread application of micro milling.And the influence of tool wear on machining process and quality is the difficult problem.(2)The machining dynamics of micro milling is analyzed.The concepts of size effect and minimum chip thickness are introduced.The tool wear mechanism in micro milling is investigated.The method of chatter stability prediction in micro milling is analyzed,and the method of chatter stability prediction with process damping is established.(3)The measurement methods of tool wear are analyzed.The tool wear in micro milling is investigated experimentally.For a more complete explanation of the tool wear,a new tool wear measurement method based on the wear area is proposed.The influence of tool wear on micro milling forces and surface topographies is studied experimentally.(4)The models of tool trajectory and dynamic chip thickness are established.The ploughing and shearing force model with tool wear is established.And the ploughing coefficients and shearing coefficients are obtained by simulation using Deform-2D.The cutting force model with tool wear is established.(5)The model of time-varying chatter stability prediction in micro milling is established.The tool wear time varying model is established by fitting the experimental data.Combined with the ploughing force model,the time varying model of process damping coefficient is established which is used to predict the chatter stability.The influence of tool wear on chatter stability of micro milling is investigated experimentally.(6)A lot of burrs generate on the machined surface during micro milling,which will affect the quality of inspection and subsequent assembly.The mechanism of burr forming was analyzed.And the influence of machining conditions and tool wear on burr formation of micro milling is investigated experimentally.