Three-dimensional Finite Element Coupled Thermal Analysis Of Hot Rolling Process And Plate Crown Variation

The modem industry requires much higher quality of the strip. The shape of the strip becomes one of the most important quality indexes which are used by the new time industry. With the requirements for the index of the strip shape become much higher by the modem industry, the precision of the longitudinal thickness of the strip is more and more high. The width of the strip, the temperature at the end of the rolling process, and the curl temperature are also strictly controlled; Compared with all the factors above, the strip shape question becomes more and more prominent. For a long time, restricted by the computer software and hardware, people doing the simulation research of the hot rolling process are mostly limited to the 2-D analysis, which cannot analyze the factors which affect the crown of the strip, while through the 3-D analysis, many important results which are related to the industrial hot rolling practice, such as the temperature field distribution of the strip, the shape of the strip, the shape of the rollers and the deficiency on the surface of the strip.The hot rolling process is a complex technology process which includes many non-linear factors such as geometric nonlinearity, material nonlinearity, and contact nonlinearity and so on. The paper has carried thermo-mechanical coupled analysis for the hot rolling process and mainly done the following research using MARC finite element analysis software.1. Based on the elastic-plastic theory and basic heat transfer formula, considered with the affection of the elastic-plastic deformation of the rolled strip and the rollers to the temperature field and the stress field, The 3-D finite element physical model was established using MARC software. Both the model and the applications of the boundary condition were similar to the reality, so that it could satisfy to the industrial requirements.2. By doing the heat simulation experiment to test the stress values corresponding to the strain values at a fixed strain rate of the material of the rolled trip, combining with the rheological stress model in the form of hyperbolic sine and including the deformation activation energy Q and deformation temperature T, which was put forward by other scholars, the constituent law of the strip material could be get.3. In order to prove the correctness of the model, the simulation of every pass was carried out. Many results such as the distribution of the temperature field and the stress field of the rolled strip, the distribution and the magnitude of the separating force could be get, which could be used to simulate and predict the crown magnitude of the strip.4. The changing law of the crown magnitude was researched by changing some technology parameters (the separating force, the bending force, the tensile force and so on), so that the method which is used to control the crown of the strip could be explored.5. The simulation of the hot rolling process which used several volumes of aluminum alloy strips was carried out. The simulation results showed that they agreed with the experiment results, which indicated that the simulation results can be used to the crown magnitude prediction in the industrial production and set the foundation for the following research.6. By doing the industrial experiments, on one hand, the boundary conditions and initial conditions needed in the hot rolling process simulation were provided, on the other hand, the correctness of the simulation results are proved. By compared with the simulation results and the experiment results, the simulation results could agree with the experiment results well, which prove that the simulation model was correct and the simulation results are authentic.