The measurement and analysis of "dogbone" and lateral spread phenomena on a universal slabbing mill

Abstract

The term "dogbone" is used to describe the shape of the cross section of a steel slab having undergone a reduction in width as a result of a vertical edger draft. Specifically, the deformation of the edges of a slab which is (by definition) of greater magnitude in width than thickness, results in the upsetting of the edges in the vertical direction, such that the slab thickness is no longer uniform. The presence of this additional dogbone thickness causes unequal and often excessive loading of the horizontal rolls in the forward pass portion of the rolling sequence of an uncompensated schedule. Inherently necessary to the study of slab dogbone is the measurement and analysis of lateral spread, for it is precisely the occurrence of spread, induced by the horizontal mill drafts, which contributes a significant portion to the total dogbone magnitude. In fact, the two effects are mutual in nature inasmuch as dogbone also uniquely contributes to the overall spread during the forward pass thickness reduction. The study presented herein illustrates a technique of measuring the described effects and analyzing the resultant data for the purpose of developing compensating equations. Furthermore, it is shown how the resultant model is implemented in an actual on-line computer controlled slabbing mill.