Calibration Method for In-Process Identification of Tangential Specific Cutting Force in Milling

Abstract

The cutting forces that occur during machining cause static and dynamic deformations of the machine–tool–workpiece system. In general, the cutting force is spatial. However, knowledge of the tangential component of the cutting force is crucial for the optimum use of the power installed on the spindle. An important parameter for cutting force modeling is the tangential cutting force coefficient. This paper focuses on the approach of the in-process identification of the cutting and edge components of the tangential cutting force coefficient, using the spindle power signal read directly from the machine tool control system. Such procedures have already been described in the available literature. The key point for the successful implementation of these methods is the identification and avoidance of the passive torque signal. This paper describes the operational calibration of the spindle drive system. The calibration procedure is based on the tap test using modal hammer excitation and the spindle power signal response. The proposed procedure was successfully validated using a machine–machine comparison approach and a machine–dynamometer validation approach. The results are consistent with those in the available literature. With this method, we were able to determine the cutting component of the tangential specific cutting force with a deviation of 1% from the reference system and an edge component of 10%. The modal hammer method only enables the avoidance of dynamometers in the machine calibration procedure.