Characterization of material flow mechanism for chamfered tools utilizing coupled slip-line-slab method

Abstract

Sintered carbide tools with their edge chamfered have superior resistance against brittle fracture of the main edge. Such advantage is mainly attributed to the formed built-up edge (BUE) anterior to the chamfer face. However, as the cutting process, certain materials including cracked BUE in that vicinity will inevitably flow aside along the chamfer face, which eventually causes severe notch wear and lateral burr formation. Given this deficiency, both theoretical and experimental works were carried out for the cutting process with chamfered tools in the current study. In the theoretical part, the material flow mechanism was analyzed and modeled by classifying the process into three typical modes concerning specific chip-tool contact patterns, for which three sets of modified slip-line solutions were developed accordingly. Furthermore, a unique solution to the three-dimensional (3-D) material flow status was achieved by combining slip-line theory with the slab method. On this basis, the effects of tool preparation factors, i.e. chamfer width, chamfer angle, tool-workpiece friction coefficient and rake angle, on the BUE extrusion were discussed in detail. The results indicate that with proper chamfered edge design, accumulative BUE will be flowing in an optimal condition. In this case, the lateral burrs were found effectively restrained as had been evidenced by conducting extensive orthogonal cutting experiments with chamfered tools. By comparing with released models and experimental measurements, the present model yields more accurate predictions of material flow states. These findings of present study can contribute to the optimal design of cutting tools with chamfered edge.