A first step towards an in-line shape compensation for UHSS roll forming

Roll forming is an important sheet metal forming process and is being used increasingly in the automotive industry for the manufacture of structural and crash components from Advanced High Strength Steel (AHSS) and Ultra High Strength Steel (UHSS). In AHSS and UHSS, the material properties can change from coil to coil or within the same coil and this can lead to varying part quality in roll forming. The effect of changes in material properties on part quality depends on the geometry of the part being formed as well as on the process parameters. There is a strong interest in developing in-line shape compensation for roll forming, and this will only be possible if the relationship between part quality, material properties, process- and part shape-parameters is understood. In this paper, the effect of material properties and both process and geometrical parameters on longitudinal bow is analysed. A new technique is introduced for the identification of variations in the longitudinal bow in a roll formed component based on roll load and torque measurements as well as process parameters and part geometry.