Modeling and Suppression of Tilt Angle of Machined Surface under Constant Feed-Rate Vector in a Five-Axis Machining Center

With the recent proliferation of five-axis machining centers (5MCs), the precision-machining field requires consistently high machined accuracy and surface quality. 5MCs enable the production of complex-shaped parts such as aerospace components, which are difficult or impossible to machine using three-axis machining centers (1). In applications requiring high machined accuracy such as mold machining, both machined accuracy and surface quality are considered critical. Accordingly, attempts have been made to stabilize the cutting force and achieve higher machined accuracy by controlling feed rates and spindle speeds. However, since machine tools inherently exhibit orthotropic anisotropy, simply standardizing the magnitude of the cutting force may hinder the realization of high machined accuracy and consistent surface quality (2). This motivated the development of a control strategy that maintains a constant feed-rate vector at the cutting point. This strategy enables higher machined accuracy and improved surface quality because the relative position between the tool and the workpiece remains unchanged. Our previous research confirmed that the tilt angle of the machined surface occurs when machining with a constant feed-rate vector at the cutting point. This phenomenon is attributed to tool deflection caused by the cutting force acting on the tool. The tool deflection can be calculated from the cutting force derived using an instantaneous cutting-force model. This study demonstrated that by appropriately adjusting the tilt axis of the 5MCs, it is possible to suppress the tilt angle of the machined surface, leveraging the characteristic that the relative position between the tool and the workpiece remains unchanged.