Study On Controlling Deviation In The Course Of Roll Zeroing On Baosteel's 1580PC Mill

1580PC mill introduced by BaoSteel company is a new type of hot rolling mill, and it can effectively control the profile and crown. It has advantages as below:large range and high accuracy to control the strip crown;control the strip profile infinitely.However,as the output has gradually increased,the equipment under the high-load critical state for a long time, equipment deterioration trend is intensified obviously,roll zeroing precision and rolling stability are gradually lower.Excessive force deviation when roll zeroing,roll gap deviation after roll zeroing, often seriously affected production.This paper will do research on the problems of excessive deviation of rolling force on two sides of the rolling mill when roll zeroing of the BaoSteel 1580PC mill.Firstly, on the base of previous study researching the whole roll zeroing process.By analysing the gap impact on the roll system state, obtain the work roll with backup roll and work roll with work roll crossing system state when gap exists.Talk about the reason for static deviation from mill rigidity,vertical direction deviation,hydraulic screw-down system,roll system's crossing and so on;Talk about dynamic deviation from axial force on the roll.And the same time use theory of preliminary displacement to calculate the axial force produced by roll crossing when roll zeroing.Using the finite element software ANSYS to calculate the static deviation caused by work roll and backup roll crossing under different gap state,and the dynamic deviation caused by different cross angle when rolling.The conclusion indicate that the main reason for unparallel gap is dynamic force deviation ,while the main reason for dynamic deviation is unparallel roll system.As for this problem,this paper issued controlling the rigidity difference and dimension difference in vertical direction of the roll system and a new method which is Cross Head Gap Self-Compensated. In theory analysis,when roll chock and the liners have a ideal function dimension,using the Cross Head Gap Self-Compensated can significantly improve the unnormal roll Cross, thereby reducing or eliminating the rolling force deviation produced by axial force.On the basic of the above theory,this paper has developed a new type of axial force sensor which is suit for the PC mill,and tested rolling force deviation and axial force of 1580PC mill when roll zeroing and rolling.Test results show that dynamic deviation is direct relation to the axial force of the roll,this is consistent to the theory.Moreover ,the tested data indicate that adjusting PC angle can influence the rolling force deviation sharply.