Abstract
This paper reports on the investigation we conducted into the mechanical cause of the pinch mark defect called heat buckling which can occur during the processing of thin steel strip in continuous annealing and processing lines. The major cause of heat buckling is the convex crown of hearth rolls. A revolving roll generates a force which compresses strip width. This in turn causes the strip to buckle and produce wrinkles. When wrinkles are crushed on the roll, heat buckling results.
We obtained a formula which shows that the critical tension at which heat buckling starts to develop is proportional to the square of the ratio between (strip thickness·yield stress) and (roll crown·friction coefficient·yield stress). Transverse temperature deviation is a cause of strip buckling, ie, center wave or edge wave. Center wave reduces the critical tension of pinch mark defect.
