Research On Final Rolling Rail Control Mechanism Of Curvature Before Straightening After Hot Pre-bending

Hot pre-bending is an important process in cooling process of the rail production,because the rail cross-section shape is complex and temperature distribution is not uniformin the cooling process, the rail generates a large bending deformation. Subsequentstraightening process is closely related to the pre-bending process. The smaller thecurvature of rail before straightening is, the smaller the change in cross-sectionaldimensions of the rail and the residual stress after cooling, it directly affects theperformance of the rail. Therefore, the study of rail curvature control mechanism beforestraightening to obtain ideal hot pre-bending process parameters, having an importanttheoretical and practical significance to enhance and improve the performance of rail.Firstly, based on the finite difference method to establish a mathematical model oftemperature field of rail cooling process, get a different final rolling temperature and finalsection of rail rolling temperature difference between the cooling process conditions. Theformula of rail curvature before straightening and section dimensions of change is derivedthrough the consideration of rail rolling bending and final section temperature field andfinal section temperature difference. And the temperature field during cooling processand the curvature before straightening can get by the C language program. Secondly, weget a reasonable amount of pre-bending acoording to the curvature before straightening;Finally, using the finite element analysis software ANSYS to simulate the cooling processof rail, and the article simulates different final rolling conditions of rail, such as straightrail, having final curvature rail and rail with different initial temperature, and gets thechanges of the rail section size under different final state of rail.Through the program computation and simulation analysis, the greater thetemperature difference between the rail section is, the greater the curvature beforestraightening is; the higher initial temperature of rail is, the greater section size of rail isafter cooling and the higher curvature before straightening is. If the temperature differencebetween the rail section is fixed, the greater curvature of rail bend to head is, the greatercurvature is; if the value of curvature final rolling bending to front is similar to the curvature before straightening, the curvature before straightening is smaller, the greaterthe difference is, the greater the curvature is. After analysis, if the pre-bending value isequals to the value of the curvature before straightening after cooling without pre-bending,the curvature before straightening is very low. Analytical calculations and finite elementsimulation results are similar after comparing the two results. Using the analyticalprocedures can quickly calculate the curvature, it is convenient to apply pre-bendingamount to rail and can achieve online calculation adjustments.