Study Of Buckling In Continuous Annealing Process Line And The Improvements

The problem of buckling related to wide steel strip in continuous annealing process line is studied in this thesis. The structure of the continuous annealing furnace and the key control technical are introduced, and the annealing process for steel strip in the furnace is analyzed. The cold rolling conditions and annealing process are closely involved to the generation of buckling problem. Both the high-temperature and the low-temperature sections in the furnace are likely to produce buckling defect. The impacts of strip buckling such as: strip properties, furnace roll, temperature and tension parameters are analyzed.Heat transfer process of the steel strip in continuous annealing furnace is analyzed to study the influence of heating and cooling conditions on the strip surface quality. The forces exerted on the strip in the real annealing process line are calculated: Strip suffers large bending stress when it is rotated around the roller; the fluctuation of the furnace temperature leads to a greater thermal stress on the strip surface.According to the actual production process, some corresponding buckling control measures are proposed: Take regular inspection and maintenance of roller, replace the furnace roller which is badly worn in time to ensure a uniform distribution of forces when the strip runs around the furnace roller and also to prevent the strip snaking in the furnace; Use low-temperature annealing process to reduce the furnace temperature level to improve the anti-buckling capacity of the strip; Adopt the transverse uniform cooling technology, so the cooling air flow could be distributed reasonably. Make sure the strip is cooled uniformly to prevent the impact of thermal stress on buckling. The optimal scheduling strategy can be used to ensure the acceptable change of the strip scale, and stable production of the strip.The result shows that the wide strip buckling defect can be significantly reduced by applying the above measures.