The Research On Evolution Of Strip Tensile Stress For Cold Rolling Process

Strip steel is the most widely rolled products in various sectors of the nationeconomy. With the continuous expansion purposes, strip steel gained rapid development,it have a very important purpose in the automotive, shipbuilding, bridges, buildings,machinery, metal products, petrochemicals and defense, and many other industrial andagricultural areas. Enterprise and customer’s requirements on geometry and mechanicalproperties of strip arc also increasing. Therefore, that more in-depth theoretical study andimprove the scientific level, improving the quality and market competitiveness of thesteel become extremely urgent.The flatness is an important quality indicators of cold rolled strip, strip shape controlis the key, cutting-edge and high-end technology of cold rolling strip. The core model offlatness control technology is the plastic deformation model of the strip, while improvingthe lateral distribution tension of the cold-rolling strip solution precision is greatimportance to perfect three-dimensional theory.This paper analyzed the characteristics of tension variation in the rolling process, theconcept of rheological tension around roll gap is proposed. According to the theory ofelasticity, in order to simplify the model the strip is treated as plane problem. The papercombines the relationship between plane stress relationship and model of the shapecontrol, and resolve rheological tension outside the roll gap zone by the finite differencemethod. In order to increase computing speed, analysis the characteristics of finitedifference calculations, the stress distribution is instead by the form fitting alternative, thecalculation accuracy is similar to finite difference method, calculate speed has improvedgreatly.This paper also studied the rolling process model. Basing on the law of volumeconstancy, a relationship between the entry and exit velocity model is established.Reference to the lateral displacement function and neutral formula as computationalmodel, the relationship between exit of gap with the neutral point velocity is established,we can get the lateral distribution of entry and exit velocity; The relation tensile stress with velocity model is putted forward, calculated by the relaxation factor iterative.Combining the model of rolling force with the elastic deformation model of rollscalculate exit gauge distribution, Making the gauge combine with the neutral model andentry and exit of velocity, and they are calculated by iterative, eventually the result willget the strip flatness and others parameters. The cold rolling6-H mill is taken as exampleto calculate and prove that iterative calculation method correctness and usability.Finally, the paper simulate offline the cold rolling6-H mill, and the offlinesimulation takes into account three main aspects, strip plastic deformation model, tensilestress rheological model and rolls elastic deformation model. Strip plastic deformationmodel consider the iterative relation velocity with strip flatness, the tensile stressrheological model calculate by finite difference method, the rolls elastic deformationmodel calculate be the segmentation model influence function method. The iterativecalculation results are more close to the actual.