FORMATION MECHANISM OF DARK LINES IN SKIN PASS MILL
In view of the dark streak defect of strip steel in the production of a two-stand skin pass mill,the macroscopic appearance of the dark streak defect was analyzed,and the reason of the dark streak formation was inferred to be the obstruction of metal flow during skin pass rolling,the accuracy of the inference is further confirmed by comparing the disappearance of the dark lines after the unit has been reformed.First of all,through the analysis of the whole force of the strip,it is determined that the main force affecting the dark streak is the temper rolling force and the friction force between the strip and the work roll.By analyzing the force and deformation of roll system and strip during leveling process,the elastic deformation model of roll system,the thickness model of strip outlet and the plastic deformation model of metal are established respectively,the calculation method of rolling force distribution along the strip is further determined by means of the simultaneous model,and the back calculation method of friction coefficient is given according to the calculation model of rolling force during leveling.On the basis of this,the force model of strip ridges is analyzed under the assumption of semi-infinite plane,and the vertical and horizontal concentrated forces are considered,in this paper,a criterion forjudging dark grain is given and named Dark Grain Index.At last,the Dark Streak Index of strip steel with different sampling thickness is calculated,and the relationship between the sampling thickness and the dark streak defect is analyzed.
skin pass unitdark linerolling forcestress modelfriction force
万方数据
维普
