Experimental Study On Surface Quality And Tool Wear Of Hot/Cold Assisted Titanium Alloy Cutting

Titanium alloy has the advantages of high specific strength,strong corrosion resistance and good high temperature performance.It has been widely used in aviation,aerospace,marine,medical and other fields.However,titanium alloy is a typical difficult-to-machine material due to its characteristics of stickiness,toughness,elasticity,and high chemical activity.The machining process has problems such as high cutting temperature,high cutting force,severe tool wear,and difficult to handle chips.Aiming at the difficult to process characteristics of titanium alloys such as high strength,low thermal conductivity,and high chemical activity,as well as the one-sidedness of traditional auxiliary cutting methods such as heating,cooling,and lubrication,and the limitations of existing combined auxiliary cutting methods,this paper proposes A new method for joint assisted turning of titanium alloys in a way that effects work together.The specific research content is as follows:?1?Dry cutting is carried out with tool wear and workpiece surface quality as evaluation indexes,test results are analyzed,and process parameters are optimized,so as to determine the parameters range of turning elements when assisted by cold and heat effects;In addition,the titanium alloy end faces are air-cooled,comparative tests of turning under oil mist lubrication and aerosol mixing conditions found that only by combining lubrication and cooling can the tool wear and surface quality be reduced at the same time.?2?Two cold-effect assisted cutting experiments of water-based cutting fluid micro-lubrication and Mo S₂ nano-fluid ultrasonic atomization were carried out respectively.Compared with dry cutting,both can significantly enhance the surface quality,reduce the build-up edge,and reduce the height of the tool flank wear.Compared with water-based cutting fluid MQL,in the low-speed cutting process with the same cutting parameters.The fluid ultrasonic atomization assist method can suppress the abrasive wear of the tool.With the increase of the cutting speed,the density and depth of the abrasive grain nicks on the flank face have not been significantly improved when MQL and ultrasonic atomization assist cutting titanium alloy.?3?Introduce high-power laser energy beam to dry turning and carry out laser thermal effect assisted cutting of titanium alloy.The effects of heating-assisted turning parameters on tool wear,tool morphology,tool wear patterns,and workpiece surface roughness were analyzed.The results show that the laser thermal effect-assisted cutting method can not only effectively reduce the depth and density of abrasive grain nicks,but also reduce the generation rate of abrasive grain nicks;the increase in laser power has improved the surface roughness of titanium alloys,but by SEM Analysis with EDS found that the higher the laser power,the higher the degree of oxidation reaction in the cutting zone,the more stickies generated,and the more pronounced the sticking knife phenomenon.?4?Combine the three cold effect assist methods of water-based cutting fluid ultrasonic atomization,Mo S₂ nano-fluid ultrasonic atomization and water-based cutting fluid MQL with laser thermal effect assisted cutting to develop titanium alloy assisted turning under the effect of thermal cooling test.The results show that the three heat-cooling composite cutting methods can not only reduce the depth and density of abrasive grain scoring,but also effectively suppress sticking and oxidative wear.When the laser power is 25W,the flank face under the combined effect of heat-cooling effect The wear height VB and the surface roughness Ra of the titanium alloy can be reduced by a maximum of 21.4%and 28.7%respectively;if the laser power is increased to 50W,the Ra of the first heat-cooling effect composite method is relatively smallest,compared with the pure laser-heat-assisted cutting,The surface roughness value decreased by 11.5%;and the second thermal cooling effect composite method,compared with the simple nano-particle ultrasonic atomization cooling effect,Ra after auxiliary cutting is relatively reduced by30.3%.It can be seen that this paper uses the method of heat-cooling effect combined processing,combining laser heating-assisted cutting and ultrasonic atomization lubrication and cooling,making full use of the advantages of material heating,tool lubrication and cooling,taking into account the high strength and low titanium alloy Thermal conductivity,while softening the strength of titanium alloy,can reduce cutting temperature,reduce tool wear,and improve machining quality.It is a green and efficient auxiliary cutting method.