高效切削钛合金Ti-6Al-4V硬质合金刀具扩散磨损研究

Study of diffusion wear of carbide tool in high- efficiency cutting Ti-6Al-4V

钛合金化学活性高,在切削过程中与硬质合金刀亲和性大,导致刀具易于发生扩散磨损。在使用硬质合金刀具切削钛合金Ti-6Al-4V试验及切削仿真分析基础上,采用SEM的EDAX研究刀具的扩散磨损,通过研究切削温度及刀-屑/工件接触区压力对扩散磨损的影响,并借助相图分析刀-工件之间的元素亲和力,进而研究扩散磨损的形成机理。结果表明:钛合金切削温度高,并且随着切削速度的增加,切削温度上升;在刀-屑以及刀-工件接触区,最高温度处于刀尖部位靠前刀面的位置。钛合金的加工回弹,造成刀-工件接触面摩擦加剧,使得整个接触区域的最高压力位置位于刀尖附近靠近后刀面的位置。在接触区的高温高压下,硬质合金刀具前、后刀面均发生元素扩散,且前刀面扩散现象比后刀面较为严重;随着切削速度的增加,加剧了扩散现象的发生。

Titanium alloy has high chemical activity and has great affinity with cemented carbide tool material,which leads to serious tool wear. Based on the cutting experiments using carbide tool and FEM,the present paper aims at studying the tool diffusion wear with SEM and EDAX. The effect of cutting temperature and the pressure of the tool- chip / workpiece on the diffusion wear is studied. Furthermore,the formation mechanism of diffusion wear is studied by means of the phase diagram. The results show that the cutting temperature is very high and it increases with cutting speeds. At the interface of tool- chip and tool- workpiece,the highest temperature is located on rake face near tool tip. The resilience of workpiece material leads to serious friction between the machined surface and tool flank face. The highest pressure is located in tool flank face close to tool tip. Under the condition of high cutting temperature and high pressure at tool- workpiece / chip interface,diffusion occurs both in tool rake and flank face.Due to the higher temperature at tool rake face diffusion in tool rake face is more severe than that in tool flank face. The increased cutting speed accelerates the diffusion.