Prediction and Control of Thermal Scratch Defect on Surface of Strip in Tandem Cold Rolling

Abstract

The thermal scratch significantly influences the surface quality of the cold rolled stainless steel strip. In order to establish a precise mathematical model of oil film thickness in deformation zone, the lubrication in cold rolling process of B443NT stainless steel strip was studied in the laboratory. According to the principle of statistics, a mathematical model of critical oil film thickness in deformation zone for thermal scratch was built, with fitting and regression analytical method, and then based on temperature comparison method, the criterion for deciding thermal scratch defect was put forward. Storing and calling data through SQL Server 2005, a software on thermal scratch control was developed in the Microsoft Visual Studio 2008 environment by MFC technique for stainless steel in tandem cold rolling, and then it was used into the practical production. Statistical results demonstrated that the hit rate of thermal scratch arrives at 91.47%, the occurrence rate of thermal scratch is decreased by 87.81%, and rolling speed is increased by 7.3%. The developed software is of significance to the control of products quality of stainless steel strips, and the analysis and solution to the problem of thermal scratch defects in tandem cold rolling.