Active error compensation in contour-controlled grinding

A new process chain for near-net-shape forged and immediately heat-treated crankshafts omits soft pre-machining by a direct grinding process. Due to distortions and allowance distribution, the forged workpiece axis differs from the optimum machining axis. In-process alignment regarding eccentricity and tilt errors is required. For tilt error compensation an active tailstock is presented here. Combined hydraulic and piezoelectric actuators move the tailstock center in two degrees of freedom to produce a workpiece counter-tilt. A varying tool engagement, cooling, workpiece deflections, control deviations and machine compliance affect the contour-controlled grinding process. Here, a model based approach for process pre-control is described.