Study Of Surface Cleanliness On 2030mm Cold Rolled Strip

With the rapid development of automobile,home appliance and other industries,the market competition for cold rolled products is becoming increasingly fierce.Users have put forward higher requirements for the surface quality of cold rolled products,and the surface cleanliness of cold rolled strip steel is also being paid more and more attention.Since putting into operation of Xichang Vanadium Sulphate Rolling and Retreat Unit in Panzhihua Iron and Steel Co.,Ltd.,the strip steel residue after rolling is too high,the average surface reflectivity is between 55%and 57%,and the surface cleanliness of strip steel is too low to meet the user's requirements.In order to improve the product quality and meet the user's requirements,this paper aims to improve the surface cleanliness of Xichang Vanadium Sulphate Rolling and Retreat Unit in Panzhihua Iron and Steel Co.,Ltd.,from the aspects of improving the process technology and improving the equipment function,the following aspects of research work are mainly carried out:(1)Through statistical analysis of production data and on-site follow-up observation,it is determined that the main reason for the low cleanliness of strip surface is the influence of rolling lubrication process.(2)The influence of iron powder content in emulsified liquid on rolling friction coefficient was studied.The problem of large deviation between calculated rolling force and actual rolling force was solved,and the accuracy of rolling force calculation was improved.The deviation of rolling force was controlled within 100 tons,which reduced the wear of grinding rolls in rolling process.(3)The working mechanism and control mode of the electromagnetic filter are studied,and the control logic and process of the electromagnetic filter are optimized.The problems of low filtering efficiency and high iron content in the emulsified liquid are solved.The filtration efficiency of the electromagnetic filter is increased from 28%to 42%,and the filtration efficiency is increased by nearly 50%.The iron powder content in the emulsified liquid is controlled steadily.(4)The physical and chemical indexes of the emulsion were optimized and solidified,the rolling emulsification process of high-surface automobile plate and high-strength steel was formulated,and the SPC control technology was implemented.The qualified rate of the main indexes was over 98%.The stable control of the technological parameters of the emulsion was realized.(5)The design and modification of emulsion injection system have been completed.The consistency of emulsion injection angle has reached 100%.The rolling lubrication condition has been effectively improved.After rolling,the longitudinal strip defect rate of strip surface has been reduced from 25%to 0,the color difference defect rate and scratch defect rate have been reduced from 6.7%to 1.1%,and the rolling stability has been improved.Through the research and implementation of the above contents,the reflectivity of strip steel surface is obviously improved,the residual oil and iron on the plate surface are reduced,and the surface cleanliness of rolled strip steel is above 65%on average,meeting the requirements of users and reaching the advanced level in the same industry.