Research And Application Of High Speed Stable Technology Of Cold Rolling Continuous Annealing Line

Cold rolled strip steel have the advantages of smooth surface,smooth,high dimensional precision,and good mechanical performance,and have the characteristics of high stamping performance,unageing and low yield point.It is mainly used in automobile,household appliances,food packaging,motor and transformer manufacturing,building materials,hardware products and other fields.SGJT company third cold rolling line products are mainly positioned as high-grade food packaging electric tin plate and high-end household appliances plate.But from the first coil on Sep.2013,the work efficiency of this line was seriously influenced by abnormal accidents which happened very frequently,In view of this situation,this paper summarizes and analyzes the problems in cleaning section,furnace section and export section.Focus on solving the problems which affects the stable production of the unit.The main work implements as follow:(1)Focus on the strip running deviation problem in cleaning section,to increase the roll convex and use double helix roll surface design are good for the control of strip running deviation according to analyzing of roll convex and roll surface form.Tension and alkali discharge are also important factors that affect running deviation of steel strip.With the increasing of rolling time,the roughness and hardness of the roller surface will also be attenuated to different degrees.In order to ensure the stable operation of strip,the cycle of roller changing will be shortened,and the installation accuracy of the roller must be measured after each roller change.(2)Work on strip breakage problem during high speed running in the cleaning section from two aspects:the cause of breakage and the control after breakage.By increasing the distance of electrode plate and removing the electrode plate lining,the strip break times during high-speed running in the cleaning section is greatly reduced.The problem that the strip head is running into furnace after strip break during high speed is solved by the modification of looper brake and optimization of line off sequence,which greatly reduces the processing time of the strip break.(3)By analyzing the deviation of steel in the furnace and exploring the mechanism of ladysong,optimizing the temperature control in each region,formulating different heating and cooling strategies for different specifications,and reducing the frequency of in-furnace deviation and ladysong.(4)For the welding seam break problem at temper mill,the emergency operation procedure is made,the precision of mechanical equipment is measured and adjusted,the function of automatic tension reduce is developed,and the shape control is optimized.(5)For the temper mill,changing rotary joint shaft to ball cage universal shaft,adjusting the gap between back up roll driving shaft sleeve and the flat head,making new changing cycle,which solves the vibration problem of temper mill.Through the work of this paper,the downtime of 1420 mm CAL is reduced,the stable running speed of the units is improved,which provides basis for the improvement of output and quality.