Automatic profile tracking of deformed surface in mirror milling based on ultrasonic measurement

Abstract

Mirror milling is an effective and environmentally friendly means to manufacture large thin-walled parts. The remaining wall thickness of such parts is supposed to be strictly controlled to balance strength and weight reduction. However, the clamping deformation will lead to overcut or undercut if the nominal tool path is directly utilized. To address this issue, it would be helpful to scan and reconstruct the deformed unknown workpiece surface and then adjust the nominal tool path. In this paper, an automatic profile tracking approach is proposed to adaptively sample the deformed surface and reconstruct the surface model, based on a multi-ultrasonic-probe measurement system. The adaptive sampling algorithm calculates the position and surface normal of the next sampling point simultaneously based on a curvature sphere, which utilizes the surface information of the local area covered by the multi-ultrasonic-probe system. Moreover, a boundary processing algorithm is proposed to ensure the sampling process is carried out inside the boundary. The feasibility of the proposed automatic measurement method was validated through experiment.