Stability analysis for the crankshaft grinding machine subjected to a variable-position worktable

This paper serves to evaluate the dynamic performance and the cutting stability of the crankshaft grinding machine. The governing equations for the 7 degrees of freedom (DOF) lumped-mass model are formulated by the Lagrange energy method. The absolute value of the maximum negative real part of the overall dynamic compliance (MNRPODC) and the limiting chip width are the main performance indicators used to explore the structure's dynamic characteristics and the cutting stability of the grinding machine in various worktable positions. The effect on system performance of the distance between the mass center of the workpiece and the worktable module in the z direction is also analyzed. Based on the stability theory for regenerative chatter model, a computer program has been developed that utilizes the three-dimensional stability lobe diagrams of the multi-DOF system to automatically identify the stable and chatter zones. Time domain simulation of the cutting conditions is used to verify the stability lobe diagrams. Finally, an optimization analysis utilizing the particle swarm optimization method is carried out to obtain the optimal design variables. The results, in terms of |MNRPODC| or the limiting critical chip width, show improvements by a factor of 6.5 and are superior to that of the prototype machine.