Improvement of accuracy for cutting force monitoring with estimated static displacement of tool spindle

Abstract

This paper proposes a method to monitor cutting force with high accuracy by combining multiple sensor signals based on a model approach. The cutting force cannot be accurately monitored by using only acceleration sensors mounted on the tool spindle because the static displacement of the tool spindle is not measured effectively. Thus, the proposed monitoring method effectively uses information on table motion to estimate the spindle's static displacement. Specifically, the relative table displacement is defined as the relative displacement between the motor encoder and the linear scale reads, from which the estimated cutting force is calculated for estimating the static displacement. Based on this, the method monitors the cutting force more accurately from the model on the tool spindle stiffness. The proposed method was evaluated in milling with the changes of cutting loads and directions. As a result, we achieved high accuracy in cutting force monitoring in milling with end mills. The experimental results confirmed that it is possible to improve the accuracy of cutting condition monitoring by using the encoder signals on the work table.