Development of a reversible top-hat forming approach for reducing flange wrinkling in flexible roll forming

Sreenivas, Achuth; Abeyrathna, Buddhika; Rolfe, Bernard; Weiß, Matthias

doi:10.1016/j.ijmecsci.2023.108359

Cited by 7 publications

(12 citation statements)

References 45 publications

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“…Previous work aimed at FRF has shown that while a stable buckle can be formed out [25] a wrinkle will always lead to an increasing wrinkling severity with continuous forming.…”

Section: Proposed Mechanism For the Ms900 Showing Wrinkling In The Angementioning

confidence: 99%

Flange buckling mechanism in incremental shape rolling of an automotive-type variable width component

Essa,

Abeyrathna,

Rolfe

et al. 2024

Preprint

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Automotive structural components from Advanced High Strength Steels (AHSS) can be manufactured with Flexible Roll Forming (FRF). The application of FRF in the automotive industry is limited due to flange wrinkling defects that increase with material strength. The new Incremental Shape Rolling process (ISR) has been shown to reduce wrinkling severity compared to FRF and therefore presents a promising alternative for the manufacture of high-strength automotive components. The current work analyses for the first time the mechanisms that lead to wrinkling reduction in ISR based on the critical stress conditions that develop in the flange. For this, finite element process models are validated with experimental forming trials and used to investigate the material deformation and the forming stresses that occur in FRF and ISR when forming a variable width automotive component. The results show that in ISR, the undeformed flange height decreases with increasing forming; this increases the critical buckling and wrinkling stresses with each forming pass and prevents the development of wrinkles towards the end of the forming process. In contrast, in FRF, the critical buckling or wrinkling stress is constant, while the longitudinal compressive stress in the flange increases with the number of forming passes and exceeds the critical stress. This leads to the development of severe wrinkles in the flange.

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“…Previous work aimed at FRF has shown that while a stable buckle can be formed out [25] a wrinkle will always lead to an increasing wrinkling severity with continuous forming.…”

Section: Proposed Mechanism For the Ms900 Showing Wrinkling In The Angementioning

confidence: 99%

Flange buckling mechanism in incremental shape rolling of an automotive-type variable width component

Essa,

Abeyrathna,

Rolfe

et al. 2024

Preprint

Self Cite

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show abstract

“…Where 𝐿 𝐷 is the effective compression length [27] which for a component with 𝐹 = 75mm has been identified to be approximately 60mm for this type of profile shape. [11]. 𝐿 ̅ 1111 and 𝐿 ̅ 1212 are the tangential moduli (Appendix).…”

Section: Stability Of Formingmentioning

confidence: 99%

“…The stability of the forming is analysed theoretically using the 'stress ratio' parameter developed in [11]. This parameter is a direct measure of the expected wrinkling shape error (MAE), that occurs in each individual flange forming pass.…”

Section: Stability Of Formingmentioning

confidence: 99%

“…Abeyrathna showed that the forming of a top-hat profile can shape out wrinkles from the previous flange forming passes [10]. Another approach used a reversible top-hat forming approach to eliminate wrinkling [11]. These previous studies aimed at improving the internal resistance of the material by increasing the cross-sectional stiffness.…”

mentioning

confidence: 99%

“…To investigate this hypothesis, the peak strain in the flange edge of a non-developable variable depth and of a developable component profile shape are calculated with a model developed in a previous study [16]. Using the calculated peak strain values, the stability parameter, 'stress ratio', is determined for each forming pass [11] to get a measure for the expected wrinkling shape error in each pass. This is followed by experimental part forming trials using high-strength steels combined with part shape measurement.…”

mentioning

confidence: 99%

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Wrinkling compensation by Flexible Roll Forming a developable profile

Sreenivas

Abeyrathna²,

Rolfe³

et al. 2023

Preprint

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Flexible Roll Forming (FRF) can form complex shapes with variable cross-sections along the length from high-strength steel. Widespread application of the FRF process in automotive manufacturing is however limited due to wrinkling defects that occur in the flange. Flange wrinkling can be eliminated by reducing the required level of membrane deformation and compressive stresses that develop in the longitudinal direction. This is conventionally achieved by reducing the severity of the transition regions but also limits the overall complexity of the parts that can be formed. Developable profiles can be created from curved creased folding without membrane stretching or compression. In FRF, such types of profiles can be formed by combining a variation in width and depth over the length of the part. This reduces the required longitudinal deformation while at the same time providing shape complexity. This study presents, for the first time, the analyses of forming a developable shape in a FRF operation. For this, first analytical equations are applied to calculate the deformation and forming stability of a developable component and of a reference variable depth component without a developable shape. This is followed by experimental FRF trials and shape deviation analysis for both forming conditions. Finally, Finite Element Analysis is used to investigate the forming behaviour of the two types of developable profiles. The results indicate that the forming of a surface developable can reduce wrinkling issues in the FRF process. However, the intermediate forming stages are non-developable, and this can lead to longitudinal compression and wrinkling issues that, if too severe, remain in the flange when the final developable shape is formed.

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Numerical and experimental analysis of edge wave defect control during TA2 circular tube cold roll forming

Yue,

Zhang,

Xiao

et al. 2024

Engineering Reports

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The increasing application of TA2 titanium profiles in marine and petrochemical industries has spurred in a growing demand for diverse forms, including U‐shaped, rectangular, and tubular thin‐walled profiles. Traditional methods like mechanical subtractive processing and extrusion, despite their prevalence, suffer from high production costs and low efficiency. As a metal sheet forming technology, roll forming stands out for its efficiency, accuracy, and capability of producing complex shapes continuously. Nevertheless, the application of cold rolling to TA2 profiles is challenging primarily due to its low elastic modulus and high yield strength. In view of this, this study employed finite element simulation to analyze the stress and strain distribution during the TA2 roll forming process, aiming to have a better understanding of edge wave defect formation mechanism. Orthogonal experiments were performed to assess the influence of frame spacing, forming speed, roll gap, and downhill amount, on edge wave defects. The findings revealed a predominant influence of the downhill amount. Maintaining the downhill volume at 0.6 times the tube diameter kept the longitudinal strain below 0.9%, effectively mitigating edge wave defects. Implementation of these optimized parameters in an actual TA2 roll forming process confirmed the reliability of the simulations. This study establishes a solid foundation for advancing the TA2 tube cold roll forming process, enhancing the production efficiency of titanium profiles, and shedding some light on current energy conservation and emission reduction.

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Development of a reversible top-hat forming approach for reducing flange wrinkling in flexible roll forming

Cited by 7 publications

References 45 publications

Flange buckling mechanism in incremental shape rolling of an automotive-type variable width component

Flange buckling mechanism in incremental shape rolling of an automotive-type variable width component

Wrinkling compensation by Flexible Roll Forming a developable profile

Numerical and experimental analysis of edge wave defect control during TA2 circular tube cold roll forming

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