Plate assembly effect and cross-section distortion of rectangular tube in rotary draw bending

Rotary draw bending is nowadays the most universal approach to produce thin-walled bent tubes. Cross-section distortion is inevitably avoided, and the plate assembly effect is a key influencing factor. To study the relevance, a 3D finite element (FE) simulation model for the rotary draw bending process of rectangular tube is established, and the cross-section distortion characters are investigated combined with experiment and FE simulation. And then, the plate assembly effect is carried out by different test schemes based on FE model. Finally, the effects of geometrical dimensions on the maximum concave distance of outer flange are derived, and the analytical function is validated to be credible and efficient. It is of significance to design process parameters and to control defects in bending process.