In-process Monitoring of Tool Damage by Active Method

Behavior of Damping Ratio with Tool Wear Development

Abstract

For monitoring tool wear in machining process, a method of diagnostic impulse excitation was discussed. The dynamic characteristics of the tool vibration, especially, damping ratio of the tool in machining process, will change with the tool wear development. In order to measure the dynamic characteristics of the tool vibration in machining, the diagnostic impulse excitation was applied to the tool in the direction of feed and then the behavior of the tool vibration was measured under some wear conditions. The behavior was analyzed through FFT and the damping ratio of the tool was measured in machining process. The damping ratio was linearly increased with the development of flank wear. The increment of the damping ratio was different in each cutting condition, but it could be uniquely determined by the area of the flank wear. The feed rate did not affect on the increment of the relation between the damping ratio and the flank wear, but the parallel shift of the relation was seen, so that larger feed rate will give the larger damping ratio. The increment of the damping ratio will be caused from the interaction between wear and cut surface. As the vibration energy is consumed in the interaction, the energy consumption mechanism was discussed. And the widely available method to monitor the flank wear was proposed and discussed with the experimental ones.