Compensation of Disturbances on Force Signals for Five-axis Milling Processes

Products and hence processes for todays manufacturing industry sectors become more and more complex in terms of geometry. Increasing quality demands furthermore prove the need for deep process understanding, product-oriented process monitoring and adaptive control of the machining process. For all of these topics production-suitable sensor solutions are needed, especially the precise measurement of cutting forces. This paper describes the application of stationary force measurement platforms for five-axis milling processes with compensated force signals. The sensor system is developed for the use on a multi axis machining centre and suitable for all processes with non-stationary workpiece axis, e.g., turning operations and five-axis milling processes. The present paper focusses on the scientific and technical challenges for the develop- ment of an appropriate measurement system for five-axis milling processes. The main technical challenges are the compensation of the dynam- ic forces, the consideration of the gravity force and the changing mass due to the metal cutting process. For this reason, information about the current workpiece position, velocity and acceleration is used for compensating forces that are not resulting from the machining process itself. The compensation of these disturbance forces is executed by means of a suitable, intelligent calibration methodology. Test results on a machine tool in a production environment and the theory for compensation will be presented in this paper. Furthermore, details about the functional design of the system will be provided.