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For sheet metal parts with the vertical-wall partially and irregularly distributed on the sides (VWPIS) that contains both the difficult-form-surface (i.e., vertical-wall) with large forming angle and easy-to-form surface (i.e., gently tilted surface) with small forming angle, a selective multi-stage two point incremental forming (SMTPIF) on the basis of the forming angle was proposed. This SMTPIF method performs multi-stage forming only for the difficult-form-surface and gives different forming strategies and forming parameters to the different surface regions according to the forming angle. The algorithms for surface zoning, generation of the small forming angle surface for vertical-wall, generation of one-stage forming model by combining the easy-form-surface and small forming angle surface were presented. Meanwhile, the algorithm for the generation of the toolpath that is suitable to the SMTPIF was also given. The effectiveness of the proposed algorithm and the SMTPIF was verified by using the case studies, the finite element analysis, and the forming experiments. The results indicate that the SMTPIF can fabricate the VWPIS with short forming time and no sinking phenomenon. [ABSTRACT FROM AUTHOR]

There are some problems in the CNC incremental forming with the sheet metal part containing vertical wall, such as excessive thinning and easy fracture. A new CNC incremental forming method was proposed based on the feature recognition for the multidirectional adjustment of the sheet metal posture. According to the feature recognition, the multi-feature of the sheet metal part was decomposed into a number of the forming feature units according to the size and distribution of the forming angles, so that the forming angles of the surface are less than the forming limit angle. The feature recognition and forming feature unit generation algorithm, sheet posture control method, and sheet posture surface generation algorithm were studied, and the finite element analysis and the forming experiments based on the proposed algorithms were also presented. The research results show that the proposed method can change the sheet metal posture in real time during the CNC incremental forming process and realize the non-rupture forming with the large forming angle parts such as vertical wall parts. [ABSTRACT FROM AUTHOR]