NUMERICAL SIMULATION AND EXPERIMENTAL RESEARCH ON WRINKLE DEFECT DURING HOT BAR ROLLING PROCESS

In the paper, surface wrinkle defect occurring during hot bar rolling process is studied with the combination of FEM simulation method and experimental method. The effect of entry width and the fillet radii of billet on displacement velocity and profile on billet corner is simulating analyzed. The calculated results have the same regularity as the experiment with continuous casting billet. It is found that the shallow crack or deeply fissures on the surface of workpiece are observed with the increase of the entry width and decrease of fillet radii of billet. All of crack regions are ditches with different sizes on the surface in optical microscope. At the same time, the flowing velocity of metal on billet corner is quite different from FEM simulation, some have so negative movement that resulting in ditches in the profile. Simulated results had the same tendency of formation of crack as the experimental results. Either result reveals that the main reason inducing surface wrinkle defect to occur during hot bar rolling process is the opposite flowing velocity of metal on billet corner.