Optimization Design Of Backup Roll Curve On Finishing Train Of 1780mm Hot Strip Mill

The shape curve of back-up roll has an important influence on the wear of roll and strip shape control.In order to solve the problems of uneven wear and tear of the back-up roll surface and roll surface falling off in the finishing mill of Chengde Iron and Steel company.and to improve the effective service life of the back-up roll,a large number of simulation calculations were carried out by using the influence function method,and various factors for strip crown and rolling were summarized.According to the influence law of contact stress distribution between rolls,a new optimum design scheme for the shape curve of supporting rolls is proposed,which takes into account the thermal expansion and transverse displacement of rolls,aims at uniform contact stress distribution between rolls and eliminating the peak value of stress between rolls.The main contents are as follows:(1)Digest the Siemens secondary process control model,analyze the role of thermal crown module in flatness control and the calculation method of roll thermal crown based on the characteristics of field process and equipment;(2)Collect and analyze the wear data of the back-up roll of the hot rolling line finishing mill,analyze the wear reason of the back-up roll and put forward the solution based on the relevant literature;add a new thermal crown calculation module for the simulation program of the elastic deformation of the roll based on the thermal crown theory,study and analyze the roll transverse movement and bending.The influence of different factors,such as roll force and strip width,on the distribution of contact stress between rolls and the crown of strip steel plate provides a theoretical basis for the design of back-up roll profile curve;(3)Based on the field data,the distribution curve of roll thermal crown with time is drawn,the thermal crown and transverse displacement are added to CVC curve,and the roll surface curves of working rolls in different time periods are fitted by least square method;the curve of back-up roll is coincided with the curve of new working roll,and a new shape curve of back-up roll is designed.line;(4)According to the eight new types of roll shape curves of back-up roll obtained from different thermal crown curves,the contact pressure distribution between rolls is calculated by using the developed elastic deformation simulation calculation program.The optimal form of the new type of roll shape curve is obtained with the goal of uniform contact stress distribution between rolls and eliminating the peak stress between rolls;(5)Compared with the roll shape curve of the back-up roll of Continuous Variable Crown,which was designed and applied in the field before,Comparing the contact stress distribution between rolls,the smoothness of roll curve and the difference of end radius.The improvement and feasibility of the new curve are verified.