| Popis: |
The mechanical state of a machined component surface was studied and three quantitative measures, namely, apparent strain energy density, strain hardening index, and residual stress distribution in a semi-infinite model, were established as parameters defining it. The surface generated by a sharp tool is discussed in the first paper of a two-paper sequence. Phase change was isolated by machining low-carbon steel in selected conditions, so as to reveal the basic mechanism controlling the surface mechanical state. The length of the shear plane (or cutting ratio) was found to be a unique parameter which determines the mechanical state of the surface layer. Mechanical state of the surface due to temperature effect cannot be separately considered from the chip-removal mechanism. The size effect appears to be significant in both removing the chip and deforming the surface. The cutting force obtained by extrapolating to zero depth of cut does not represent the force deforming the surface. |
