Research on the CNC incremental forming based on multidirectional real-time adjustment of the sheet posture
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ORIGINAL ARTICLE
Research on the CNC incremental forming based on multidirectional real-time adjustment of the sheet posture Hu Zhu 1 & Jilong Li 1 Received: 25 November 2019 / Accepted: 10 August 2020 # Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract 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. Keywords CNC incremental forming . Multidirectional sheet metal posture . Vertical wall . Forming angle
1 Introduction The sheet metal CNC incremental forming is a flexible and dieless forming technology developed in recent years [1, 2]. This technology uses a squeezing tool to form the sheet metal parts by pressing the sheet layer by layer according to the forming toolpath, which can be widely used in prototype trial production and multi-variety small batch production, and has broad application prospects in aviation, automobile, and shipbuilding industries [3, 4]. However, at present, the difficulty in incremental forming is the forming of the vertical wall part with large forming angle, and the technology still has problems in the forming of the vertical wall part with large forming angle such as excessive thinning and rupture, which seriously restricts the further development of the technology [5, 6]. To overcome the maximum wall angle constraint observed in incremental forming, researchers have explored a variety of multi-stage or multi-pass, toolpath strategies that can improve formability but often cause undesirable stepped features [7]. * Hu Zhu [email protected] 1
College of Mechanical and Electrical Engineering, Shenyang Aerospace University, Shenyang 110136, Liaoning, China
The existing researches [8, 9] show that the thickness t of the sheet is thinned according to the cosine law t = t0 cos θ, in which t0 is the original sheet thickness and θ is the forming angle. In order to solve the problems mentioned above, it is necessary to reduce the forming angle of the vertical wall surface to be less than the forming limit angle. The forming angle θ is the angle be
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