Numerical Computation Methods for Modeling the Phenomenon of Tool Extraction

Tool extraction is a phenomenon, where the end mill slips out of the shrink-fit chuck in axial direction during the cutting process. This leads to severe damage of the workpiece, the tool and in some cases even the machine spindle. So far, this is an unexplained problem with no repeatability. In this article, experimental investigations such as scanning electron microscopy (SEM) and residual stress measurements on the clamping surface of shrink-fit chucks affected by tool extraction are presented. Furthermore, results from experiments on a special testrig and a mathematical approach, which aims at the prediction of failures due to Process Machine Interaction, are described. Within the mathematical approach, a finite element model of the tool and the tool holder is linked with a cutting force simulation. The dynamic behavior of the spindle is determined by frequency response function measurements. From these measurements, a modal model is deduced and coupled with the finite element model of the tool holder. The presented mathematical model is used to compute the resulting stresses in the interface of those components due to process forces.