Research On Multi-roller Straightening Standstill Locking System Of High Tensile Reinforcement And Finite Element Simulation

High tensile reinforcement has become the mainstay of reinforced concrete steelwhich used for high-rise buildings and major infrastructure, in order to construct resourceconservation and environment friendly society and improve the security of large buildings.The phenomenon that reinforcement rotate around its own axis occur easily in the processof uncoiling and roller straightening, which may effect the precision of straightening. Thetechnology of reinforcement standstill locking has always been a difficulty in the study ofreinforcement roller straightening. Practice proves that three-roller standstill lockingsystem has a good effect for ordinary reinforcement, but it is easy to cause serious scratchon the surface of high tensile reinforcement when straightening due to the contact stress islarger. In this paper, a multi-roller equal straightening reinforcement standstill lockingmechanism is proposed, which based on the design method of multi-section deformationand unified curvature, furthermore, systematic study of multi-roller reinforcementstandstill locking and equal curvature mechanism and simulation verification is conducted.In this paper, spinning process of high tensile reinforcement production is studied,and mechanical properties change of reinforcement in spinning and cooling process isanalyzed, besides, the reason why reinforcement twist elastically when uncoiling isrevealed, moreover, analytical formula of reinforcement torsion angle is derived.Reinforcement elastic recovery torque equation is established and precise value of elasticrecovery torque when uncoiling and straightening is derived on the basis of mechanicsanalysis in reinforcement elastic recovery torsion process.The multi-roller straightening reinforcement standstill locking mechanism is putforward, and parameter calculation and structure design is conducted. The roll diameter isdetermined according to bending and contact strength conditions, and roller spacing andaxis coordinate of each roller in normal work is established in accordance with the rollerdiameter and reinforcement large bending deformation conditions.By using the elastic-plastic deformation and mechanics of materials theory, the force applied to reinforcement by rollers was calculated through force analysis. Rollingreduction of upper standstill locking rollers is figured out by using the finite differencemethod, and elastic rolling reduction of upper pinch rolls are calculated by using the Hertzcontact formula. Reinforcement standstill locking condition is established by mechanicsanalysis. Principle of large deformation to equal curvature is further analyzed, and unifiedcurvature value of reinforcement after passing the multi-roller straightening reinforcementstandstill locking mechanism is derived.The process of multi-roller or three-roller reinforcement standstill locking andmulti-roller equal curvature is simulated respectively by using the nonlinear finite elementanalysis software ANSYS/LS-DYNA. The superiority of multi-roller standstill locking isproved through comparative analyzing the effect of standstill locking and deformationbetween the reinforcement standstill locking process of multi-roller and three-roller. Thefunction of unified reinforcement curvature which multi-roller straightening reinforcementstandstill locking mechanism possess is validated through simulating the process ofmulti-roller equal curvature.