Mechanics, dynamics and thermal analysis of hard turning process

Abstract

ABSTRACT In precision machining, due to the recent developments on the cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better and deeper understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. In order to enlarge the capability profile of the hard turning process, this thesis introduces to prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field of chip, tool and workpiece are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FERE-1 (Fiberoptic Ratio Pyrometer). ill