Investigation of the effect of roll forming pass design on main redundant deformations on profiles from AHSS

The tooling design in the roll forming process plays a major role in the quality and successful mass production of a variety of complex profiled products, in many industrial sectors. The roll forming line is comprised of consecutive forming passes. Each roll forming pass consists of a set of rotating rollers able to bend the material as it passes through them. The roll forming pass design plays a major role in the production of profiles. The introduction of advanced high strength steels (AHSS), such as the DP-series and TRIP-series, has also posed new challenges for the design of the roll passes. The current paper exploits explicitly the finite elements (FE) method and investigates the effect of the roll forming passes design on main redundant deformations, such as longitudinal stains at the edge of the profile, shear strains on strips plane, thickness reduction, and final produced cross section with springback. The profiles discussed are symmetrical V-and U-sections from the AHSS Dual Phase series (DP780). The gradual lowering of the flower pattern design, known as "downhill pass flow", is discussed. The calculated decrease in the peak longitudinal strains of up to 28%, and the decrease in thickness of up to 38% are also presented and discussed.