The Effect of Forming Strategy on the Longitudinal Bow in Roll Forming of Advanced High Strength Steel

摘要

In roll forming, the sheet is deformed gradually in successive roll stands. The tooling design plays a major role in the quality of the roll formed parts. Two design strategies are possible, constant arc length and constant bend radius. The former offers an overall bending curvature greater than that from the latter. This implies a larger compression and stretching in the profile along the forming process is possible. This has a significant effect on the final quality of the roll formed parts. Although a wide range of research has been carried out on roll forming process, up till now no case has been found in the literature considering this effect. Therefore, the key significance of this paper is to investigate the optimal roll forming process design, and hence improve the quality of the rolled products in terms of longitudinal bow. For this purpose, Finite Element Analysis (FEA) was used to model the roll forming process with two design approaches, constant arc length and constant bend radius, by using Abaqus standard. A material hardening model was imported from a developed inverse routine of cyclic pure bending test, and then integrated into FEA- model of roll forming. A forming radius R15 mm of V- shaped profile made of DP78 has been formed using five forming stations. Longitudinal bow was determined and analyzed. It was observed the longitudinal bow has been decreased by 50% for the constant bend radius compared to the rival one. This study assists the roll forming process designer to improve the final quality of the products.