Research And Simulation On Straightening Shear Bending For The Steel Bar

With the development of production and technology in our nation, the government pay more attention to the infrastructe construction. The need for steel bar, which as an indispensable building material, grows year by year. The HRB400 steel bar, which is popularized by Buildings Department, has a high yield stress. The statistical data of completed project shows that, the usage of HRB400 steel bar is about 15% less than the usual bar. The traditional machine tool can not guarantee the quality of bar because of the high yield stress. Therefore, the study on straightening, bending and slitting of high yield bar has important theoretical value and practical significance.Based on the straightening theory, analyzed the relationship between curvature and stress and strain during the process of straightening. Introduced the theory of roll straightening and tension-leveling. Established the the finite element model and straighten the bar with different elongation rate. Compared the straightening force, straightness and residual stress of straightening, and choosed the optimal elongation rate.According to the hoop-bending machine with profile modeling, the relation was deduced between rotation of rotary-table and hoop angle. Based on the spring-back theory, the relation was deduced between hoop angle and spring-back angle. Establish the model of hoop based on the finite element analysis software, analysed the influence on spring-back angle under different hoop speed, different radius of gyration and different diameters, the result can be used as reference for the design of hoop-bending machine and the precision of the hoop.The shear deformation of the steel bar and the changing process of shear force have been analyzed. Establish the model of shear and sheared the steel bar with different clearance and shear velocity. The curve of shear force has been extracted. Compared the curves under different clearance, the optimal clearance were confirmed. The unit resistance curve under different shear velocity has been producted after data processing. Analysed the influence of shear velocity on relative cutting depth and the largest unit resistance.