Theoretical Analysis and Experimental Study of Springback Mechanism of Archwire Bending

Abstract

Archwire is the material with high elastic and high strength property. Archwire bending forming using robot belongs to the typical big curvature bending process. In order to ensure its one-step forming, it is really important to study its spring back mechanism. This study proposes a theoretical model to predict springback in archwire bending. This model which considering the neutral line does not coincide with central line is based on the true stress and strain data obtained from tensile test. The effection of bending moment arm on springback is also considered. The springback theoretical calculation formulas of archwires whose cross-section are rectangular and circular are derived, respectively. Then an archwire bending robot is used to bend archwire into different angle and a metallurgical microscopy is used to measure formed angle. The experimental results indicate that the proposed theoretical model could accurately predict the springback angle. Furthermore, the formed angle shows a general increase with the bend angle. And in elastic deformation clearly stage, although springback angle itself is small, the proportion of it in bend angle is very large. In plastic deformation clearly stage, although springback angle itself is large, the proportion of it in bend angle is relative small.