Ti40阻燃钛合金切屑形成和铣削力波动特性研究

Research on characteristics of chip formation and milling force fluctuation of Ti40 burn resistant titanium alloy

Ti40阻燃钛合金是beta型钛合金,在切削过程中,切削变形复杂、切削温度高、切削力大且波动大,使得刀具磨损破损十分严重。通过对切屑金相图片进行观察,研究Ti40切屑形态及形成机理,同时对Ti40阻燃钛合金的铣削力波动特性进行分析,分析切屑形成过程、机理与铣削力波动特性之间的关系。结果表明:晶粒内部生成大量绝热剪切带,切屑厚度呈不规则变化,形成的锯齿形切屑表面上有大量微锯齿和明显的微裂纹产生;随着切削速度升高,绝热剪切带形成频率提高,显著锯齿形切屑形成,剪切变形带之间亚晶粒数量显著增加和细化。铣削力在波峰上发生了显著波动,波动次数和幅度与显著锯齿形切屑形成相对应。铣削力波动是锯齿形切屑形成过程中发生了绝热剪切和振动导致的切削方向改变等综合因素引起。

Ti40 burn resistant titanium alloy is one kind of beta phase titanium alloy.There existed complex cutting deformation,higher cutting temperature,higher cutting force and fluctuations,and serious tool wear and damage in the process of machining Ti40 alloy.In this paper,the chip formation characteristics,chip formation mechanisms and their relationships with dynamic fluctuation force of Ti40 beta titanium alloy are analyzed.It is shown that shear bands are formed inside the deformation of each beta phase grain,its chip thickness varies irregularly,and there exists micro-serrated teeth and micro-cracks on the serrated chips.With cutting speed increasing,the formation frequency of adiabatic shear bands is lifted,notable serrated teeth are formed and the sub-grains are formed more obvious and fine among adiabatic shear bands.At peaks of milling force,notable fluctuation is shown,and the fluctuation times and amplitude are corresponded to the formation of notable serrated teeth.The fluctuation of milling force is caused by adiabatic shear and cutting direction change due to vibration.