Deformation Property of Eccentric Tube in Press Bending Process

Tubes are widely applied as structural members and members for fluid transmission. However, there is a concern that the strength of the tube will decrease because thickness deviation will occur during bending and the thickness on the tension side will decrease. Therefore, the authors devised an eccentric tube that eccentric the inner diameter of the tube and increases or decreases the thickness in the tube. In this study, we conducted an experiment and Finite Element Analysis (FEA) for the purpose of researching the deformation property of the eccentric tube and evaluating the appropriate value of the eccentricity e. As a result, it was found that, as a deformation property of the eccentric tube, even if there is a difference in thickness in the same tube, the thickness deviation becomes large in the case of thin wall. Furthermore, it was found that the flattening was reduced by setting the thick part of the eccentric tube to the tension side. In addition, the target value of the thickness after processing was set, and the eccentricity e at which the thickness after bending was close to the target value was estimated by FEA. As a result of conducting an experiment using the obtained eccentricity e, it was found that the thickness after processing can be made close to the target value by adjusting the eccentricity e.