Experimental study on high-speed hard cutting by PCBN tools with variable chamfered edge

The cutting edge structure of PCBN tools has an important influence on cutting force, chip morphology, and tool wear in hard cutting process. In order to evaluate the cutting performance of PCBN tools with variable chamfered edge, this paper carried out comparative experiments of high-speed hard cutting hardened steel GCr15 by PCBN tools, respectively, with variable chamfered edge and uniform chamfered edge, and proposed the detection index and measurement of macroscopic and microscopic morphological characteristics of chips, and found the variation rule of cutting force, chip morphology, and tool wear over cutting time. The experimental results showed that under the effect of helical cutting edge, the axial and radial load of the PCBN with variable chamfered edge, to a certain extent, was decomposed, which resulted in relatively smaller radial force and axial force; in the state of no tool wear, the macro morphologies of chips generated by the two cutting tools with different chamfered edges, were both wavy, however, with the increase of cutting time, the chip morphology of the cutting tool with uniform chamfered edge changed from being wavy into being irregularly curved, while the one of the cutting tool with variable chamfered edge remained invariable. In contrast, as for the cutting tool with variable chamfered edge, the margin of its rake crater wear is relatively far away from the cutting edge, and it has obvious advantages in improving the chip removal performance and tool life, and reducing the cutting resistance.