Generation mechanism and forecast model of coil bulging defect

For the bulging defect of the hot rolling steel coil after discharging, through a large number of field tracking and theoretical research, combined with the support characteristics of the hot rolling steel coil after discharging, a simple analysis about the bulging defect mechanism was made from the point of mechanics, a new concept, the amount of bulging, was proposed for the first time to represent the degree of bulging defect. Considering the non-circular feature of each coil strip, the asymmetry of stress distribution along the circumferential direction, the influence of gravity and possible slip, the existing gap between layers, by starting from the internal stress model and strip bending deformation model of the hot rolling steel coil after discharging, a prediction model of the amount of bulging is put forward for the hot rolling steel coil, and it has been applied to the production practice and has achieved good effect. This model has realized quantitative forecast of "bulging" defect degree for the first time with prediction error within 15%, meeting the engineering requirements and laying a solid theoretical foundation for the comprehensive management of the bulging defect.