Effect of Tension Rolling on Internal Compactness of Big Size Bars

With the help of the finite element simulation software Msc.Marc, through introducing the deformation theory of rigid plastic compressible materials, the internal rarefaction levels of workpieces were assessed by the relative density, a three-dimensional finite element model for the rolling of big size bars with internal rarefaction was established. The influences of different tensions on the workpieces internal relative density, rolling force and amount of spread were analyzed. The simulation results were verified by the actual continuous rolling experiments of big size bars. The results show that the internal rarefaction in big size bars was reduced effectively by using the negative tension rolling. However, the rolling force, rolling torque and amount of spread increased at the same time. When using negative tension rolling to improve the internal density of big size bars, the factors which determined the size of negative tension such as the mill capacity, the pass-filling degree and so on should be put into consideration. The negative tension stress should be controlled at about 4 MPa in continuous rolling. The simulation results were in general accord with field rolling results.