科研之友
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摘要
The tool edge has a significant influence on a cutting process especially when it is comparable to uncut chip thickness. Generally, the cutting tool edge is considered rounded and is characterized by a tool edge radius. When the cutting tool edge geometry is not a symmetrical circle, the tool edge radius fitted with the former methods is not sufficient to describe the performance of the cutting edge. In this study, a parameter, which is different from the previous description method, is proposed to characterize the tool edge. Three different tool edges are reconstructed to investigate the effect of the proposed parameter on a nano-cutting process using molecular dynamics. Results show that combined with the former used tool edge radius, the newly proposed tool edge characterization parameter which is the tool edge radius fitted with the edge profile at the flank face side could be used to characterize the cutting performance of an asymmetric tool edge. The minimum uncut chip thickness, subsurface damage, and cutting force in feed direction investigated in this study tend to increase with the newly proposed characterization parameter. A stagnation region formed in front of the cutting edge acts as a new formed cutting edge making the material removed in shearing mechanism when the uncut chip thickness is larger than the minimum uncut chip thickness. However, when it is similar or smaller than minimum uncut chip thickness, the stagnation region is not tough enough to cut the materials making it to slide on the surface and part of the atoms in the upper layer of workpiece is removed by extrusion. Two models are proposed to describe the shearing and extrusion mechanism in a nano-cutting process.
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