Research On Cutting Performance Of CFRP And CFRP/Ti Stacks In Unit Edge End Milling Cutter

Carbon fiber composite(carbon fiber reinforced plastics,CFRP)is an advanced structural material with high specific strength,high specific modulus,fatigue resistance,corrosion resistance and excellent comprehensive properties.But it has the characteristics of anisotropy,heterogeneity,high hardness and brittleness and low heat dissipation.Especially in the slotting process,burr and other damages and serious tool wear are easy to occur.Superior comprehensive properties of CFRP/Ti stacks can be obtained by the synergistic effect of the two materials on their properties.Its application in aircraft structure is more and more extensive.While titanium alloy has poor thermal conductivity,high temperature chemical property and low elastic modulus.Due to the great difference in properties of the two materials,the surface quality in milling is difficult to guarantee,the tool wear is serious and the durability is low.The chip removal performance and heat dissipation of the unit edge end milling cutter are improved by the chip break groove structure.It can effectively restrain the fiber defect and reduce the effect of the temperature produced by cutting titanium alloy on the surface integrity.In this paper,the cutting experiments of CFRP single layer plate and CFRP/Ti stacks material are carried out by using the unit edge end milling cutter.The main contents of the research include the following aspects.Firstly,according to the material properties of CFRP and titanium alloy,the unit edge end milling cutter was analyzed from the aspects of reducing fiber defect and cutting temperature.At the same time,the experimental schemes of CFRP single-layer plate grooving and CFRP/Ti stacks material side milling were designed respectively.It laid the foundation for the study of tool wear,surface quality and cutting force.Secondly,the evolution process of tool wear in CFRP slot milling process was studied.It was found that the wear of the coated end milling cutter with unit blade has experienced two stages,i.e.coating particle wear and coating shedding.The microstructure of slot wall and burr defects of CFRP single-layer plate with different fiber orientation were analyzed.The influence of cutting tool wear and cutting parameters on cutting force was also studied.Thirdly,the wear process and mechanism of CFRP/Ti stacks material were studied.It was found that the wear patterns at both ends of the cutting edge wear band became more and more different with the cutting.Due to wear mechanism such as abrasive and adhesive wear in the cutting edge of titanium alloy,the surface of the cutting tool was mainly composed of layer adhesion of titanium alloy material and coating tear.The wear in the cutting edge of carbon fiber was relatively slight,and the cutting edge of carbon fiber was mainly bluntness under the action of hard abrasive particles of carbon fiber.With the aggravation of tool wear,the breakage of titanium alloy cutting edge appeared gradually under the action of mechanical stress and thermal stress.Finally,the evolution process of machined surface morphology of CFRP/Ti stacks with unit edge milling cutter was studied.At the beginning of milling,the surface morphology of titanium alloy and CFRP workpiece were relatively smooth.However,as tool wear intensified,the surface of titanium alloy workpiece first appeared cutting tool ripple and scratching trace.At this time,the thermal load on the machined surface was gradually increasing.With the continuous accumulation of thermal load,the surface morphology of CFRP became irregular,and the defects such as resin coating and fiber residue appeared gradually.