Investigation of clamping force for a high-speed shaft with toolholder using contact element analysis

The main characteristic of a motor built-in high speed spindle with ATC is to perform high-speed cutting. The drawbar mechanism of spindle provides the clamping force to grip the toolholder for machining. Poor connection between the shaft-taper hole and toolholder will cause the danger of toolholder to loose and slip. In this study, a solid modeling method is adopted to investigate the effects of clamping force provided by the drawbar mechanism. Contact analyses of the toolholder and shaft-taper hole using contact elements are conducted. The stresses distribution between the toolholder and shaft-taper hole is then obtained. The effects of pre-stress are then adopted for subsequent finite element modal analysis. The finite element modal analysis results are verified by the experimental modal testing. The results presented herein indicate that it is effective in simulating and analyzing the contact relationship between the toolholder and shaft-taper hole by using contact elements. Also, it is proved that the shaft-toolholder system can provide different friction torque to resist the cutting force due to different clamping forces and coefficients of friction.