Research On Critical Technologies Of Ultrasonic-Assisted Milling For Particle-Reinforced Titanium Matrix Composites

Particle-reinforced titanium matrix composites(PTMCs)are based on Ti-6Al-4V titanium alloys,and are a novel genre of metal matrix composites with high hardness and high modulus reinforcing phases.Excellent physical and mechanical properties such as high specific modulus have broad application prospects in aerospace,biomedical,automotive and marine industries,but in the actual processing process,there are serious tool wear and negative surface quality.technical challenge.Therefore,this paper adopts the ultrasonic-assisted milling method to carry out experimental research on the machinability of PTMCs from the aspects of material removal rate,cutting temperature,cutting force,surface roughness and tool wear,which provides theoretical and theoretical basis for ultrasonic-assisted milling of PTMCs.Technical support is of great significance to optimized cutting parameterand,improve surface quality and improve processing technology.The main research work and results obtained in this paper are as follows:(1)Based on the kinematics theory,the motion trajectory equation curve of the cutting edge of the tool is drawn,and the instantaneous cutting thickness and instantaneous cutting depth models are established.Combined with the motion trajectory length of the cutting edge,the mathematical model of the material removal rate is derived.Compared with ordinary milling,exert on the tool axis direction of ultrasonic high frequency vibration can improve the material removal rate.(2)The cutting temperature of conventional and ultrasonic-assisted milling PTMCs were investigated.With the increase of milling speed,milling width and feed per tooth,the cutting temperature of the two machining methods showed an upward trend,and decreased slightly with the increase of the content of reinforcing phase;the cutting temperature of PCD tool was about the same as that of carbide tool.Ultrasonicassisted milling can reduce the cutting temperature by about 4.2%～14.3%.For cemented carbide tools and PTMCs with a reinforced phase content of 8%,the cutting temperature is reduced by about 5.3%～10.3% and 10.4%,respectively.(3)The cutting forces of conventional and ultrasonic-assisted milling PTMCs were investigated.The cutting three-direction component force of both machining methods increases with the increase of milling speed,milling width,feed per tooth and reinforcing phase content.The cutting force of PCD tool is about 85%～90% of that of cemented carbide tool.Ultrasonic-assisted milling can reduce the cutting force by about3%～23.1%.The cutting force of the cemented carbide tool and the reinforced phase content of 8% is reduced by about 6.2%～10.9% and 6.4%,respectively.(4)The variation law of surface roughness,three-dimensional surface topography and typical tool wear characteristics of ordinary and ultrasonic-assisted milling PTMCs were explored.Tool wear is mainly caused by particle shedding on the rake face,micro chipping and abrasive wear on the flank face;the surface roughness obtained by using PCD tools is about 70% to 80% of that of carbide tools;The surface roughness of the machining method increases with the increase of milling speed,milling width and feed per tooth,and the surface roughness of ultrasonic milling is always low,and the reduction range is about 7.6%～17%;the surface roughness of ultrasonic milling.The peaks and troughs of the three-dimensional topography fluctuate more uniformly,the surface defects such as particle scratches and holes are reduced,and the surface quality obtained is more preferably.