The work rolls of large four-high rolling stands are driven via universal joint drive shafts. After every rolling cycle the height of the rolls is adjusted. The drive shafts must follow the adjusting movement. Therefore they have universal joints. Due to the height adjustment, the shaft length varies as well, which has to be compensated in a coupling sleeve. The universal joint shafts are generally very long to ensure that the deflection angles do not become too large. Because of the high torques which have to be transmitted they are strong and heavy.
In larger rolling mills, the weight of universal joint shafts is supported in split single or double row cylindrical roller bearings in order to relieve the joints and couplings from the weight. Changes in the position of the universal joint shafts are compensated in the housing suspensions. The split bearing design is necessary as the flanges forged to the universal joint shaft are considerably larger than the shaft diameter at the bearing seats. In the past few years, several rolling mills were already successfully converted from sliding bearings to rolling bearings. This has reduced the maintenance expenditure and, in particular, grease consumption siginificantly.
Publisher: Schaeffler Technologies AG & Co. KG