REU 2010 – Mathematical Modeling of Cobbling Instabilities In Steel Rod Fabrication

In the manufacture of steel rod and bar, a steel billet (with cross-section area of approximately 200 – 250 cm2) get heated to more than 1000°C (1830°F) and then passed through a series of rolling stands. These stands have pairs of rollers with shaped grooves that deform the billet such that the cross-sectional area is reduced, while elongating it into a very long and relatively narrow workpiece. To maintain high productivity of the steel mill, the processing lines should run smoothly, with each billet running in a continuous manner. However, there are instances when the workpiece tangles within the equipment, causing the operation to stop and possibly damaging the rolling equipment. These failures are called “cobbles” in the industry. This project is focused on developing mathematical models in highly nonlinear geometries in order to help identify the dominant mechanisms of cobbling under different operating conditions.