Benefits of stress superposition in combined bending-linear flow splitting process

P Groche,C Taplick,P Mahajan,M Özel,S Stahl

doi:10.1007/s12289-016-1325-4

P Groche, C Taplick + Show 3 more

Open Access

https://doi.org/10.1007/s12289-016-1325-4

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Abstract

Linear flow splitting is a multi-station sheet-bulk metal forming process which allows continuous production of bifurcated profiles without joining, lamination or external heating of sheet metal. This process induces high hydrostatic stresses in the forming zone which leads to an elevated formability of the workpiece material. The aim of this research is to bend linear flow split profiles in transverse direction in a continuous manner. This is achieved by combining the linear flow splitting process with a continuous bending process. An analytical and a numerical model are described in this paper which predict bending moments for different radii. Results from both models are validated with experimental results. It is found that combining the linear flow splitting with a bending process leads to a severe reduction in the bending moments due to superposition of stresses in the forming zone. The superposition maintains the cross sectional shape of the bent profiles.

Highlights

Demand for high strength steel profiles has increased strongly due to requirements to reduce fuel consumption by weight reduction [1]
The geometrical flexibility can be increased by preforms produced through the linear flow splitting process [2, 3]
The objective of this study is to propose a method which will allow for bending linear flow split profiles with a constant cross-section in a continuous manner without any expensive tool change costs

Summary

Introduction

Demand for high strength steel profiles has increased strongly due to requirements to reduce fuel consumption by weight reduction [1]. This is indicated by a statistic of the fabrication of flat rolled steel within Germany which has quintupled since the 1950s [2]. By arranging the rolls in a multi-station line, a continuous production of bifurcated profiles from the sheet metal is possible [5]. It is possible to use the roll formed linear flow split profile as a preform for hydroforming [7, 8]. A number of technologies are available to bend the profiles such as three-roll bending, stretch bending, laser bending (Fig. 1)

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Conclusion