The Significance and Impact of the Utilization Coefficient and Stiffness System in Rolling Mills

Here, we discuss two coefficients related to rolling mills—utilization coefficient and stiffness coefficient—and elaborate on their respective meanings and the methods used for their calculation.

The utilization coefficient of a rolling mill refers to the ratio of the theoretical rolling pace to the actual rolling pace achieved in practice. It is commonly used to reflect the degree of imbalance in the rolling pace of the mill and the difference between the practical hourly output and the theoretical hourly output.

In situations where the rolling mill operates without stopping, the loss of time is the fundamental cause of the imbalance in the rolling pace. Several factors contribute to the occurrence of time loss. On the one hand, it may result from operational errors by personnel, such as failure to feed the workpiece into the groove, slippage of the workpiece, or unsuccessful steel turning. On the other hand, it may be due to time delays caused by disharmony between preceding and succeeding processes. Additionally, time loss can occur during the production process due to malfunctions.

In summary, a higher utilization coefficient indicates better utilization and a higher level of operational proficiency for the rolling mill. Conversely, a lower utilization coefficient suggests poorer utilization and lower operational proficiency. To improve the utilization coefficient, it is necessary not only to enhance operational proficiency and the mechanization and automation of the production process but also to reduce the impact of human factors on the fluctuation of rolling pace and strengthen harmonious cooperation between preceding and succeeding processes.

The stiffness coefficient of a rolling mill represents the rolling force required to induce longitudinal unit elastic deformation in the mill, equivalent to the slope of the linear segment of the mill's elastic curve. This parameter can be calculated based on the slope of the mill's elastic curve.

In practice, due to the temperature rise of the rolling rolls and the entire mill under the load effect during rolling, the gap between the rolls undergoes changes, becoming a variable. Additionally, the roundness and installation errors of the rolling rolls can lead to periodic variations in the longitudinal thickness error of the rolled piece. Therefore, to enhance the accuracy of thickness control for rolled pieces, the stiffness coefficient of the rolling mill is generally determined through on-site measurement methods.