The origin of end flare in roll formed profiles

M Moneke,P Groche

doi:10.1007/s12289-021-01640-w

M Moneke, P Groche

Open Access

https://doi.org/10.1007/s12289-021-01640-w

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Abstract

Roll forming is a continuous manufacturing process designed for large batch sizes. In order to economically produce roll formed parts with smaller batch sizes, the process setup times have to be reduced. During the setup, profile defects and especially the deformation caused by the release of the process-inherent residual stresses, also known as end flare, have to be counteracted. However, the knowledge regarding the creation of residual stresses is limited and the ability to reduce end flare usually depends on the experience of the process designer and the machine operator, which makes the setup time-consuming and cost-intensive. Therefore, in this paper the creation of end flare during the roll forming process is investigated in depth. As a result of this study explanation models for U-, C- and Hat-profiles, which link the creation of residual stresses to the local deformation during the forming process, are developed. Knowing how changes in the forming curve affect the creation of end flare allows to use a knowledge-based approach during the design and setup process, thereby reducing time and costs.

Highlights

Due to the global trend of increasing individuality within the product design process and shorter product life cycles, the industrial requirements of forming processes have changed
Plastic transversal strains at the band edge (PU,8) are not induced due to transversal bending, but rather due to transversal contraction resulting from the longitudinal strain
The creation of plastic strain and residual stresses is investigated for U, Hat- and C-profiles

Summary

Introduction

Due to the global trend of increasing individuality within the product design process and shorter product life cycles, the industrial requirements of forming processes have changed. In order for the serial production process roll forming to fulfill these requirements, the setup time after a change of the profile geometry has to be minimized. Roll formed products such as seat rails have to be manufactured with a high dimensional accuracy, which requires a high number of forming stations. Due to imperfect roll design and roll positions, wear and tear or fluctuations in the material properties, deviations from the dimensional accuracy and profile defects can occur, which have to be manually corrected before the Especially the profile deformation at the cut-off, which is known as end flare and occurs due to process-inherent residual stresses (Fig. 1), has to be precisely counteracted to satisfy production tolerances [1]. Since the creation of residual stresses during roll forming depends on the actual forming conditions at the roll forming machine, whereas the deformation can only be observed after the cutting, the correction process is time-consuming and creates waste

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