Research And Simulation On The Roller Shape Of The Two-Roller Thin-Walled Tube Straightener

Because of light, sufficient strength, stiffness and toughness, the thin-walled tube has already become an important component in mechanical devices, widely used in the car, defense, aerospace and other high-tech fields in recent years. But it may generate different degree’s bending and deformation in its production and processing because of the influence of the external force, the changeful temperature and so on. Therefore, it is an very important procedure to straighten the thin-walled tube in metal processing.The tube mainly uses the cross-roller straightener for straightening. The cross-roller straightener is composed of the two-roller straightener and the multi-roller straightener. The multi-roller straightener relies on stagger bending of each roller to straighten. The two-roller straightener relies on the changeful curvature in the roller gap of a pair of roller to straighten and its straightening precision is higher than the multi-roller straightener. At present, few domestic scholars research on the thin-walled tube straightener. While the curvature of the existing tube straightener is larger, which may lead to the thin-walled tube produce some defects and cause a higher waste products rate when straightening it. This paper mainly studies the problem of the thin-walled tube straightening. In order to obtain a higher precision of straightening, this paper studies the two-roller straightener. The roller shape of two-roller straightener decides its straightening precision. Therefore, this paper focuses on the study of the roller shape.Firstly, this paper deduces the relationship between the curvature radius and the elastic region ratio from the straightening principle and calculates the critical minimum bending radius values before the defect of fracture, flattening of cross-section and medial wrinkling in straightening thin-walled tube. Compared to the bending radius value in the allowable elastic region ratio, it finally determines the design basis and the value range of the optimal curvature radius. Secondly, this paper compiles a calculation software of roller shape parameter by the Visual Basic programming software. Afterwards, according to the theory of elastic-plastic bending, this paper designs a new single curvature roller shape. This roller shape guarantees the inner wall of thin-walled tube have a certain elastic deformation zone during the straightening process, which is not easy to appear the phenomenon, such as the tube to be crushed. Finally, according to the specific example, this paper establishes the3D finite element model of the thin-walled tube straightening, simulates the straightening process and analyzes the change of all parameters in the straightening process based on the finite element ANSYS/LS-DYNA platform, which provides the theoretical guidance for practical application.