On-line Inter-stand Tension Monitor System for Bar Mill

In wire rod and bar mills, it is important to optimize inter-stand tensions in order to prevent problems during rolling and to prevent dimensional variations in the longitudinal direction. The stabilization of inter-stand tension, however, has hitherto been dependent on the adjustment skills of operators. This paper relates to a method that was developed to estimate inter-stand tensions on the basis of a model for wire rod rolling. This model uses the values of motor current, which can easily and constantly be obtained during rolling without relying on the skills of the operators. A tension monitor system was newly developed to provide the rolling mill operators with inter-stand tension estimated in real time using the above method, and this monitor was introduced to the bar rolling mill at the Kobe Works of Kobe Steel. As a result, the system has facilitated the motor speed adjustment performed by the operators. This contributes to the stabilization of the inter-stand tension in actual operation and to the reduction of operational troubles.