Upgraded Kalman Filtering of Cutting Forces in Milling

Giovanni Totis,Zoltan Dombovari,Marco Sortino

doi:10.3390/s20185397

Abstract

Advanced piezoelectric dynamometers with a wide frequency bandwidth are required for cutting force measurement in high-speed milling and micromilling applications. In many applications, the signal bandwidth is limited by the dynamic response of the mechanical system, thus compensation techniques are necessary. The most effective compensation techniques for a full 3D force correction require an accurate and complex identification phase. Extended Kalman filtering is a better alternative for input force estimation in the presence of unknown dynamic disturbances. The maximum bandwidth that can be currently achievable by Kalman filtering is approximately 2 kHz, due to crosstalk disturbances and complex dynamometer’s dynamics. In this work, a novel upgraded Kalman filter based on a more general model of dynamometer dynamics is conceived, by also taking into account the influence of the force application point. By so doing, it was possible to extend the frequency bandwidth of the device up to more than 5 kHz along the main directions and up to more than 3 kHz along the transverse directions, outperforming state-of-the-art methods based on Kalman filtering.

Highlights

Measuring the cutting forces during milling operations plays a fundamental role in the development of advanced cutting tools that should enhance the cutting process performance
According to the classical calibration procedure, the dynamometer should be loaded along different directions in order to derive the entire map between the applied input Rk and the sensed output Rdyn,i components of the resultant force R
RCSA and TPA techniques to predict the combined dynamics of the workpiece–dynamometer system

Summary

Introduction

Measuring the cutting forces during milling operations plays a fundamental role in the development of advanced cutting tools that should enhance the cutting process performance. For this purpose, special dynamometers having a wide frequency bandwidth are required [1]. Special dynamometers having a wide frequency bandwidth are required [1] This is even more critical in modern applications, where the use of small cutter diameters at high cutting speeds is not restricted to micromilling applications. Cutting force sensors will probably be integrated into next-generation machine tools. Together with other additional sensors, they will allow the effective application of in-process advanced control strategies based on the digital twin concept [2].

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Conclusion