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To enhance the machining efficiency, curved thin-walled parts in the aerospace and automobile industries are often formed to the near-net shapes and then subtractive manufactured to their design shapes. The billets for the manufacturing process may lack of the removal material in some regions due to low forming accuracy, which would increase the rejection rate of these parts. However, there is a chance that some rejected billets can be saved by using partial tolerance ranges to compensate the shape errors of the raw billets. Aiming to reduce the rejection rate and save the production cost, this paper attempts to develop a novel approach for constructing process shape of curved thin-walled part, in which its nominal shape was slightly changed within their tolerance ranges to avoid the undercut during the machining process. Firstly, a registration algorithm was used to find an optimal position between the design shape and the on-machine measurement points. Afterwards, a non-linear constrained optimization model was established to search for the feasible points in the tolerance ranges, in which the profile occupancy, thickness occupancy and non-uniformity of machining allowances were carefully considered. Finally, a new process shape was constructed based on these feasible points, which could be used for adaptive machining of curved thin-walled part. The results of a case study validated the feasibility of the proposed process shape construction approach. • The framework for a novel process shape construction approach was presented for adaptive machining. • A non-linear constrained optimization model was established to search for the feasible points in the tolerance ranges. • The profile occupancy, thickness occupancy and non-uniformity of machining allowances were carefully considered. [ABSTRACT FROM AUTHOR]

Localization plays an important role in manufacturing the curved thin-walled parts, which can determine the distribution of machining allowance and has great influence on the manufacturing accuracy. The registration algorithm is the most efficient way to locate the billet in the machining coordinate system of the machine tool by computing a transformation matrix. However, the localization of the curved thin-walled parts is complicated and challenging since the billets are individual, the shape and location of which are unknown. This paper attempts to develop an adaptive localization approach with the constraints of the profile and thickness based on on-machine measured data. The framework for constrained adaptive localization approach is illustrated, in which on-machine measurement, registration, isometric mapping and allowance optimization are involved. The details of the on-machine measurement for both the profile inspection and the thickness measurement are presented. An isometric mapping method is employed to build the separate point pairs between the measured points and the nominal shape of the part. A constrained optimization algorithm for the machining allowance is performed iteratively until meeting the constraints of the profile and thickness tolerance ranges. Finally, a case study of constrained adaptive localization was carried out, the results of which confirm the validity of the proposed approach. [ABSTRACT FROM AUTHOR]