Analysis of residual stress state in sheet metal parts processed by single point incremental forming

Author(s):  
F. Maaß ◽  
S. Gies ◽  
M. Dobecki ◽  
K. Brömmelhoff ◽  
A. E. Tekkaya ◽  
...  
Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 656 ◽  
Author(s):  
Fabian Maaß ◽  
Marlon Hahn ◽  
A. Erman Tekkaya

The residual stress state of a sheet metal component manufactured by metal forming has a significant influence on the mechanical properties, and thus determines the time until the component fails, especially for dynamic loads. The origin of the resulting residual stress state of incrementally formed parts with regard to the forming mechanisms of shearing, bending, and the normal stress component is still under investigation. The relationship between the process parameters, the forming mechanisms, and the resulting residual stress state for a complex part geometry manufactured by single point incremental forming (SPIF) is presented in this publication. For this purpose, a validated numerical process model is used to analyze the influence of the step-down increment Δz for truncated cones on the characteristics of the forming mechanisms and the resulting residual stress state. For the first time the forming mechanisms are evaluated numerically on both sides of the formed component. A relationship between the process parameters, forming mechanisms, residual stresses, and the mechanical properties of an incrementally formed component is shown. Shearing-induced hardening is identified as a relevant influence on the residual stress state of cones.


2009 ◽  
Vol 623 ◽  
pp. 37-48 ◽  
Author(s):  
Steeve Dejardin ◽  
Jean Claude Gelin ◽  
Sebastien Thibaud

The paper is related to the analysis of shape distortions and springback effects arising in Single Point Incremental Forming. An experimental set up has been designed and manufactured to carry single point incremental forming on small size sheet metal parts. The experimental set up is mounted on 3-axes CNC milling machine tool and the forming tool is attached and move with the spindle. Experiments have been carried out on sheet metal parts to obtain tronconical shapes. The forming strategy associated to the movement of the forming tool has been also investigated. The experiments indicate that shape distortions arising in the corners of the tronconical shape are clearly related to forming strategy. The springback of rings cut in the tronconical parts have been also investigated. It is shown that positive or negative springback could be also related to forming strategy. In order to enhance experimental investigations, Finite Element simulations of the incremental sheet forming have been performed. Results obtained from the simulations prove that if boundary conditions and forming strategy carefully are taking into account, the finite elements results are in good agreement with experiments. So it is then possible to use FEM as a design tool for incremental sheet forming.


2007 ◽  
Author(s):  
Shigekazu Tanaka ◽  
Tamotsu Nakamura ◽  
Kunio Hayakawa ◽  
Hideo Nakamura ◽  
Kazuo Motomura

CIRP Annals ◽  
2005 ◽  
Vol 54 (2) ◽  
pp. 88-114 ◽  
Author(s):  
J. Jeswiet ◽  
F. Micari ◽  
G. Hirt ◽  
A. Bramley ◽  
J. Duflou ◽  
...  

2021 ◽  
Vol 343 ◽  
pp. 04007
Author(s):  
Mihai Popp ◽  
Gabriela Rusu ◽  
Sever-Gabriel Racz ◽  
Valentin Oleksik

Single point incremental forming is one of the most intensely researched die-less manufacturing process. This process implies the usage of a CNC equipment or a serial robot which deforms a sheet metal with the help of a relatively simple tool that follows an imposed toolpath. As every cold metal forming process, besides the many given advantages it has also some drawbacks. One big drawback in comparison with other cold metal forming processes is the low accuracy of the deformed parts. The aim of this research is to investigate the sheet metal bending mechanism through finite element method analysis. The results shows that the shape of the retaining rings has a big influence over the final geometrical accuracy of the parts manufactured through single point incremental forming.


2020 ◽  
pp. 1-15
Author(s):  
Yue Lin ◽  
Wei Shen ◽  
Lifei Song ◽  
Enqian Liu

To meet the demand of automatic production, the multisquare punch forming has been improved to process complex curved plates. However, the improved forming equipment improves the processing quality to the maximum extent, and springback and residual stresses are inevitable phenomena in the cold bending process. Residual stress is an important factor that causes fatigue crack and stress corrosion crack. And the residual stress in machining will seriously affect the fatigue life of cold-pressed parts. Therefore, it is necessary to quantitatively and qualitatively analyze the residual stress caused by the cold forming equipment. Through theoretical derivation and finite element simulation methods, the residual stress distribution for thick plates in the cold forming process was analyzed and compared in this article. Meanwhile, the variation law of residual stress peak with thickness and forming radius was further discussed. The results show that the residual stress distributions obtained by the two theoretical models are in good agreement with the numerical results. The maximum error of peak residual stress is about 10%, which verifies the reliability of theoretical formulas. 1. Introduction A large number of complex curved sheet metal parts are used in aerospace, marine structure, automobile, and other manufacturing industries, which makes the processing and forming of complex curved sheet metal parts attract much attention. In the process of ship construction, the forming and processing of hull plates is an important part of the low intelligence, time-consuming, and serious constraint on shipbuilding automation. Strictly speaking, most of the parts in the hull plate are three-dimensional curved surfaces, most of which are composed of complex undevelopable spatial curved surfaces. It is a very difficult and urgent key technology to process a ship's steel plate into complex three-dimensional curved surface shapes. such as saddle shape or sailed shape (see Fig. 1A), to create a streamlined outer body of the ship. For many years, bending of plates with complex curvatures has been carried out by manual operation, i.e., the combination of heat line forming and rolling bending (see Fig. 1B). However, the production efficiency of the thermoforming process is relatively low, and environmental pollution is relatively serious with bad working conditions and high labor intensity. Moreover, the forming quality depends more on the experience of technicians, and quality cannot be guaranteed. With the increasing demand for automation, the multipoint forming equipment was developed and used for stamping and forming of curved plates.


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