Characterization of the longitudinal bow during flexible roll forming of steel sheets

Woo, Young Yun; Han, Sang Wook; Hwang, Taehyun; Park, Ji Yeong; Moon, Young Hoon

doi:10.1016/j.jmatprotec.2017.10.048

Cited by 33 publications

(9 citation statements)

References 12 publications

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“…For concave blanks, a positive longitudinal strain is required at the flange zone. 18 Therefore, unlike the case of convex blanks, the longitudinal bow has a negative value. As shown in the figure, the presence of holes increases the longitudinal bow height as in the case of a convex blank.…”

Section: Resultsmentioning

confidence: 99%

“…Their results showed that the thickness reduction rolling process decreases the maximum bow height while the springback angle and end flare increase. Woo et al 18 investigated the effect of intermediate leveling rolls on the reduction of longitudinal bows in flexible roll forming. This research showed that the leveling rolls efficiently reduce the longitudinal bow for thick blanks, whereas edge wrinkles may occur in thin-walled blanks.…”

Section: Introductionmentioning

confidence: 99%

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Effects of circular holes on the web warping of perforated blanks in flexible roll forming

Kang

Woo

Moon

2018

Proceedings of the Institution of Mechanical Engineers, Part B:

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To meet the demands of highly functional parts, high-precision manufacturing technology that can provide sound semifinal perforated components having variable cross sections is frequently required. When a relatively short blank is formed into a variable section by a flexible roll forming process, web warping such as longitudinal bows and crossbows can be generated in the formed products. In this study, the characteristic features of web warping occurring in the flexible roll forming of perforated blanks were investigated both numerically and experimentally. In order to investigate the cause of web warping, the stress and strain variations during flexible roll forming are examined in terms of the shapes of blank and hole orientations of perforated blanks. The results show that longitudinal bows and crossbows are primarily caused by the nonuniformity of longitudinal and transverse strains between the flange and the web. In addition, the degree of web warping is sensitive to the shapes of the blanks and the hole orientations. From the process analysis, a guideline for the perforation of holes in convex, concave and trapezoid blanks is proposed to reduce web warping.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of circular holes on the web warping of perforated blanks in flexible roll forming

Kang

Woo

Moon

2018

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…Woo et.al Characterized the longitudinal bow during FRF of steel. They investigated the effect of leveling roll on longitudinal bowing, the results show that longitudinal bowing was reduced with the use of three blank shapes when leveling roll was applied to a FRF process [11]. Ruixue et.al investigated the Stretch bending and springback of profile in the loading method of prebending and tension.…”

Section: Fig 2 the Verticality Of Rollers In Different Positions On The Bending Curvementioning

confidence: 99%

Anisotropic Analysis of Springback in FRF Process With Variable Cross Section Using Hill and Barlat Criteria

Panahizadeh

Asl

Saeedi

et al. 2021

Preprint

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The Flexible Roll Forming (FRF) process with the ability to produce parts with variable width and depth was formed to be used in industries such as automotive, construction, and similar industries. One of the disadvantages of this process is the spring-back defect, which prevents the desired profile from being achieved. In this paper, experimental and numerical analysis of the spring-back phenomenon using Hill, Barlat, and Von Mises yield criteria. Also, the effect of bending angle, material, and sheet thickness parameters on this defect was investigated. The process for the three types of 1050 aluminum, low carbon steel, and 430 stainless steel was simulated using the VUMAT subroutine of Abaqus software. In these simulations, for each material, three thicknesses of 0.4, 0.7 and 1 mm with bending angles of 25 and 45 degrees were considered. Experimental experiments were performed using the FRF machine. Validation of numerical simulation results was performed by comparing experimental results. The results showed that the Barlat criterion has a more accurate prediction of spring-back than the other two criteria. The results also showed that the spring-back ratio of sheets with a thickness of 0.4 mm compared to 1 mm for low carbon, aluminum, and stainless steel are 1.5, 2.5, and 3.2, respectively.

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“…Channel products with constant and variable cross-sections can be formed by chain-die forming technique. The quality of sheet metal products is crucial for industrial applications, and springback and longitudinal bow are two of the most typical shape errors in gradual forming processes, especially for manufacturing AHSS products considering their large springback and complex material behaviors [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, they proposed that a downhill strategy is an effective method to eliminate the longitudinal bow. Woo et al [11] studied the characteristics of the longitudinal bow in flexible roll-formed U profiles using three different blank sheets, trapezoid, convex and concave, and the longitudinal bow defects were ascribed to the transversal non-uniformity of the longitudinal strain. Badr et al [20] studied the influence of two roll forming approaches (constant bend radius and constant arc-length method) on springback and longitudinal bow of Ti-6Al-4V sheet.…”

Section: Introductionmentioning

confidence: 99%

Springback and longitudinal bow in chain-die forming U and hat channels

Liang

Liu

Zou

et al. 2021

Int J Adv Manuf Technol

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Chain-die forming is an emerging sheet metal technique for manufacturing advanced high strength steel (AHSS) products. Springback and longitudinal bow are two of the major shape defects in gradual forming. In this study, the springback and longitudinal bow of AHSS in chain-die forming of hat and U profiles are investigated through experiment and finite element simulation. The disparity of springback along the longitudinal direction and disparate longitudinal bow signifies complex deformation processes of chain-die forming. Finite element simulation of the chain-die forming process gives an insight into the formation of non-uniform springback and longitudinal bow. The gradual forming process by one die block after another causes bending and reverse-bending deformation in the web area and the redundant deformation of the sheet metal, which further leads to non-uniform bending moment and accumulated stresses along the longitudinal direction. At the same time, the redundant deformation will also result in the longitudinal strain on the edge, while the 2 downhill deformation decreases the maximum longitudinal strain at the edge and introduces the longitudinal strain on the web. The different non-uniform longitudinal strain distribution along the transversal direction causes disparate longitudinal bow behaviors for chain-die formed AHSS hat and U profiles, downward bowing and upward bowing respectively. By the established model, the disparate springback and longitudinal bow behavior can be determined, which also contribute to the process design for chain-die formed AHSS products.

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Characterization of the longitudinal bow during flexible roll forming of steel sheets

Cited by 33 publications

References 12 publications

Effects of circular holes on the web warping of perforated blanks in flexible roll forming

Effects of circular holes on the web warping of perforated blanks in flexible roll forming

Anisotropic Analysis of Springback in FRF Process With Variable Cross Section Using Hill and Barlat Criteria

Springback and longitudinal bow in chain-die forming U and hat channels

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