Indirect Force Measurement Using Spindle Currents for Grinding Processes in Aerospace Industry

Abstract

In aerospace industry grinding is an essential manufacturing process for the production of turbine blades. After casting the blades, several millimeters of stock material are removed by profile grinding processes. In order to maximize productivity, high depth of cut values are achieved leading to considerably high process forces. By measuring and monitoring grinding forces, important information about the process can be gained, e.g., about the mechanical load acting on the component and the wear development of the tool. However, it is difficult to measure these forces directly in serial production. Therefore, this paper presents an approach for an indirect force measurement determining grinding forces using the spindle current. For this purpose, extensive experimental surface grinding tests were conducted measuring the process forces with a dynamometer and the spindle current with current clamps. A cross validation was subsequently performed in order to evaluate the best regression model for the indirect force measurement. The proposed model was validated on surface and profile grinding processes as well as on the grinding process of a turbine blade from serial production. The paper shows that for the high process forces common in aerospace industry, the model achieves good results even with simple models. The presented model can be calibrated quickly and easily, which makes this approach particularly interesting and attractive for industrial applications.

Keywords: Grinding; Force; Measurement; Spindle Current