Effect of forming sequence on product straightness and springback in roll forming

In roll forming a given profile, it is well-know that the selection of increments in deformation
in each pass can influence shape defects in the final product. In this work, the forming of a simple vee-channel
in a dual phase steel sample was studied. Four different roll pass designs were used and the distribution of
edge strain in the flange measured using electrical resistance strain gauges. Bow and springback were
measured for each setting.
It was found that, as expected, the greatest peak strain at the edge of the flange occurred where the bend angle
increment was greatest. For uniform bend angle increment, bow was least, while for springback, the setting
that gave the greatest increment in strain in the last two passes resulted in the least springback. In this work,
those settings that had the highest strain gradients at the start and the end of the process resulted in the greatest
bow.