Instantaneous cutting-amount planning for machining deformation homogenization based on position-dependent rigidity of thin-walled surface parts

Thin-walled parts with curved surfaces are widely used in industrial applications, and the surface quality is a basic requirement to ensure the functional performance. Due to the thin-walled and curved geometric features, the rigidity for this kind of parts is not only low but also position-dependent. In this way, the deformation of such parts is easy to vary and complex along the toolpath in the machining process, which results in a poor dimensional quality for the thin-walled parts with curved surfaces. However, it is a novel idea that when the machining deformation is homogeneous, the deformation compensation is easily carried out and the improved machining quality can be obtained for the thin-walled curved surface parts. For the machining deformation is affected by the cutting force and the cutting force is affected by the instantaneous cutting-amount in essence, an instantaneous cutting-amount planning approach based on the position-dependent rigidity of thin-walled curved surface parts is proposed in this study, so as to homogenize the machining deformation thus improving the machining quality. Inspired by the generalized Hooke law, the instantaneous cutting-amount is planned here to be harmonious with the rigidity variation along the toolpath, so that the ratio between the cutting force and the rigidity, i.e. the deformation at certain cutting-position, can be kept as a constant value. For this sake, the instantaneous cutting-amount of thin-walled curved surface parts during the five-axis machining process is first modeled, and then, the position-depended rigidity of the parts is calculated. Finally, the instantaneous cutting-amount is scheduled according to the position-dependent rigidity. Experimental results verify the effectiveness of the presented method in homogenizing of the machining deformation. Achievements of this study are significant for enriching the high-quality machining technique of thin-walled parts with curved surfaces.