Investigation of twist in curved hat channel products by elastic-plastic finite element analysis

This study concerns twist phenomena occurring in curved hat channel products and aims to clarify the causes of twist using physical quantities obtained by finite element analysis. Several drawing heights were examined. We evaluated the torque around the longitudinal axis, which can be regarded as the driving force of the twist. In addition, transitions of the torque during the process of tool removal were analyzed. After removing the die and blank holder, the twist torque in models with larger drawing heights became negative, accounting for the positive twist, which occurs after punch and pad removal. On the other hand, the twist torque in models with smaller drawing heights remained positive, accounting for the negative twist. Such analyses of the transition of twist torque provide useful information when considering measures for reducing twist.