The hot preflex cooling and compound straightening are the last two consecutive deformation processes and determine the straightness, residual stress and cross-sectional size for fabricating hundred-meter heavy rail products. The compound straightening process needs to be adjusted by the preflex cooling status. For studying the straightness, residual stress and cross-sectional size of heavy rail products, the preflex cooling model (including the residual stress) of heavy rail after cooling should be taken as straightening model for studying the compound straightening. In this paper, the results by ANSYS implicit analysis (geometry model and stress state of the cold heavy rail) is fully imported to the compound straightening by ANSYS/LS-DYNA explicit analysis through an implicit-explicit conversion method, which resolved the connection problem of coupling and analysis models for solving complex models in multi-physical fields. It is very significant for solving the similar problems in engineering.

The cooling process of heavy rail is the important step to the output, that the preflexed rail is cooled on the stepping-type cold bed which has been carried by the chain transmission device. We employed the finite element method to analyze the bending deformation of the U75V rail through natural cooling process, the effected factors including the rail side-laying on the cold bed, the latent heat of phase change, and the thermal radiation are considered in the analysis. In the paper, we discussed the establishment of the heavy rail cooling model, the cooling parameters and the boundary condition, and emphatically analyzed the rail bending deformation changes and its principles through the cooling process. The study of the hundred-meter high speed heavy rail can provide the theoretical foundation and reference value to the formulation of cooling technical parameters and preflex technical schedule.

When rolled heavy rail is on the cooling bed for natural cooling, the heat transfer coefficient has important effect on the bending and section sizes of cooled heavy rail. In the paper, the heat-stress couple module ofANSYS software is adopted to carry on numerical simulation on the cooling process of 60kg/m U75V heavy rail, and we obtain the change rule that heat transfer coefficient has effect on bending curvature and section sizes of cooled heavy rail. This study is of great reference value on cooling bed design and the formulation of cooling technological parameters for high speed heavy rail.

Uneven distribution of temperature is one of the important factors which influences heavy rail bending changes during the cooling process. Through the research of temperature field can reasonable analysis the heavy rail bending change rule, so it is necessary to study the temperature change rule during heavy rail cooling process. This paper adopts finite element analysis software ANSYS to set up three-dimensional models of U75V heavy rail and the cooling bed, and numerical simulate the cooling process. In which, it is studied the temperature changing rules and its distribution rules, emphatically analyzed temperature changing rule during the phase transition phase, and got the temperature changing rules and distribution rules in final cooling time. Especially, it is considered that the heavy rail placed on its side, the latent heat of phase transition and thermal radiation. This research can provide the theory basis and the advisory opinion on the formulation of cooling technological parameters and preflex regulations of the rail.