Research and verification on neutral layer offset of bar in two-roll straightening process

A neutral layer must be existed in the metal material deformation. Traditional two-roll straightening theory ignores the migration phenomenon of neutral layer, especially for large cross-sectional bar in the straightening process. Neutral layer has a large impact on straightening springback and then affects the roller shape design, process parameters, and straightness accuracy of bar. In the present work, a neutral layer offset model was established in the bar straightening process based on the three-point bending and elastic-plastic pressure. The neutral layer migration phenomenon had been studied through the model in the bar straightening process, combined with room-temperature tensile test and bending test. The relationship of neutral layer offset values and reverse bending radius and plastic deformation capacity of the metal has been obtained. The neutral layer offset model provides a reference to further study of bar straightening mechanism and deformation.