The narrow strip steel production line of Taishan Iron & Steel Co., Ltd. has been built for several years. The finishing mill group of the production line is composed of 2 vertical roll mills and 6 flat roll mills. Among the 6 flat roll mills, 3 were short-stress two-high 450 mills and 3 were four-high 450 mills. With the continuous increase of production, more and more phenomenon of on-line burning of bearings in the work roll of four-high 450 rolling mill, the main reason is that the rolling roll axial channeling makes the operation side thrust bearing force is too large and caused by (when the roll through the steel, the work roll channeling to the operation side, the support roll channeling to the drive side, channeling momentum is 5~6mm). On-line burning of bearings not only affects the output, but also increases the cost, so reducing the number of on-line burning of bearings has become an urgent problem to be solved.

1 Analysis of axial channeling of roll 

       The axial shifting of the rolling roller is the main reason for the damage of the thrust bearing of the work roll of four-high 450 rolling mill, because the axial force of the thrust bearing has exceeded its rated load. The damage of thrust bearing will cause the damage of four columns of cylindrical bearings. Under normal conditions, the causes of axial force can be found out through force analysis. The assembly of the roll system is shown in Figure 1 (the working roll and the upper support roll among the four rolls are taken as research objects). FIG. 2 shows the stress of the roll system when the steel is crossed. According to the principle of force balance, the resultant force of the work roll and the support roll in normal operation is zero, and their axes are parallel. Work roller: ∑Fx=F1-N1=0, ∑Fy=P1-P1 '=0; Support roller: ∑Fx=N2-F2=0, ∑Fy=P2-P2 '=0. The phenomenon of rolling roller axial channeling occurs when the steel is passed, which indicates that the roll is acted by axial force. According to the channeling direction indicates that the work roll is subjected to the axial force to the operating side, and the supporting roll is subjected to the axial force to the driving side. The rotation direction of the roll system during work is shown in Figure 3 on the next page (taking the upper work roll and the upper support roll among the four rolls as the research object), and the axial force on the work roll and the support roll is shown in Figure 4 on the next page.

According to the analysis of the running direction of the work roll and the support roll, there are two possibilities as shown in Figure 4-1, 4-2 when passing steel. Figure 4-1 shows that if the work roll line is perpendicular to the rolling center line, the support roll will have the deviation as shown in the figure. Figure 4-2 shows that if the support roll line is perpendicular to the rolling center line, the work roll will have the deviation shown in the figure. These two cases indicate that the projection of the axis on the horizontal plane has crossed phenomenon or the extension of the axis has crossed, so that the work roll and the support roll produce a huge axial force.