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.

为了提高加工效率，航空航天和汽车工业中的弯曲薄壁零件通常形成为近似最终形状，然后将减法零件制造成其设计形状。由于较低的成型精度，某些区域的制造工艺坯料可能缺少去除材料，这会增加这些零件的废品率。但是，有可能通过使用部分公差范围来补偿原始坯料的形状误差来节省一些废钢。为了降低废品率并节省生产成本，本文尝试开发一种构造弯曲薄壁零件加工形状的新方法，该方法是在公差范围内略微改变其公称形状，以避免加工过程中出现底切处理。首先，配准算法用于在设计形状和在机测量点之间找到最佳位置。然后，建立了非线性约束优化模型，在公差范围内寻找可行点，并仔细考虑了轮廓占有率，厚度占有率和加工余量的不均匀性。最后，基于这些可行点构造了新的加工形状，可用于曲面薄壁零件的自适应加工。案例研究的结果验证了所提出的过程形状构建方法的可行性。建立了非线性约束优化模型，在公差范围内寻找可行点，并仔细考虑了轮廓占有率，厚度占有率和加工余量的不均匀性。最后，基于这些可行点构造了新的工艺形状，可用于曲面薄壁零件的自适应加工。案例研究的结果验证了所提出的过程形状构建方法的可行性。建立了非线性约束优化模型，在公差范围内寻找可行点，并仔细考虑了轮廓占有率，厚度占有率和加工余量的不均匀性。最后，基于这些可行点构造了新的加工形状，可用于曲面薄壁零件的自适应加工。案例研究的结果验证了所提出的过程形状构建方法的可行性。