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Currently, more and more tailor-welded blanks (TWBs) are used in the automobile industry. It is very important to locate the weld line and predict its movement during the forming process. The initial weld line can be predicted by one-step finite-element analysis according to the desired weld line in the final workpiece. Meanwhile, weld line movement during the deformation process can be evaluated in advance. In this paper, the procedures of finite-element analysis of one-step FEM with TWBs are established. The contact between tool and blank and the effect of restraining forces under the blankholder due to drawbead and blankholder pressure are considered as well. Forming limit diagram (FLD) is used to show not only the tendency of reduction in thickness and fracture but also of increase in thickness and wrinkle. Hydraulic controlled pads used to clamp the weld line during the deep drawing process are simplified as static external force to eliminate the movement of the weld line. In order to speed up and ensure the convergence of Newton-Raphson iterations, energy-based 3D mesh mapping algorithm is introduced to obtain the initial solution. The above-mentioned methods have been implemented in the authors’ in-house one-step FEM code InverStamp. A rectangular cup drawing case demonstrates that this approach can be easily implemented to evaluate weld line movement and develop initial blank in sheet metal stamping with tailor-welded blanks. [ABSTRACT FROM AUTHOR]

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]