高速切削Ti6Al4V锯齿形切屑形成的表征

深入研究锯齿形切屑的形成过程及表征有利于工业生产中的切屑控制。用锯齿频率、锯齿化程度及绝热剪切带间距来对锯齿形切屑进行表征。鉴于Ti6Al4V在加工过程中易于形成锯齿形切屑,因此选择Ti6Al4V作为工件材料,通过高速切削Ti6Al4V实验,收集不同切削速度和每齿进给量下的锯齿形切屑;将获得的锯齿形切屑进行抛磨及腐蚀后,在VHX-600 ESO数码显微镜下观察切屑形貌,计算不同切削条件下锯齿频率、锯齿化程度及绝热剪切带间距。结果表明:随着切削速度的提高,锯齿频率及锯齿化程度增大,绝热剪切带间距减小;随着每齿进给量的增大,锯齿频率减小,锯齿化程度及绝热剪切带间距增大。锯齿化程度可以作为普通切削、高速切削及超高速切削的判据。

Characteristics of serrated chip formation in high speed machining Ti6Al4V

A deep understanding of the generation and characteristics of serrated chip formation can obtain some practical advices of controlling this type chip in engineering applications. The characteristics of serrated chip including the frequency of serration, the degree of segmentation and the space of adiabatic shear band are comprehensively investigated in this paper. Experiments of high speed milling Ti6Al4V were performed. The investigated material is Ti6Al4V since it is prone to form serrated chip in machining process. The chips of Ti6Al4V under different cutting speeds and feed per tooth were collected during machining. After inlay and polishing process for the collected chips, the chip morphology could be observed by VHX 600 ESO digital microscope. The expressions of the frequency of serration, the degree of segmentation and the space of adiabatic shear band were determined through microcosmic observation. The results show that the space of adiabatic shear band gets decreased with the increase of cutting speed and the feed per tooth. On the contrary, the frequency of serration will get increased with the increase of the cutting speed and it will get decreased with the increase of the feed per tooth. The increase of cutting speed or the feed per tooth could intensify the degree of chip segmentation. The degree of segmentation can be used as the criterion of ordinary cutting, high speed cutting and ultra high speed cutting.