In order to increase the steel output, the steel mill has increased the rolling force to 5000-9000T, which means that the load of each bearing is as high as 2500-4500T (without impact coefficient). The rated dynamic load of the rolling bearing can not meet the increased load. In the use of the requirements, the technical reform was forced to replace the rolling bearing with a sliding bearing. Since the investment of the hydraulic bearing of the sliding bearing is more than 20 million yuan, and the friction loss is more than 10 times higher than that of the rolling bearing, the annual energy loss of a rolling mill is hundreds of thousands of yuan. In addition, the oil gap of the static and dynamic sliding bearing is greatly affected by the load variation, which affects the uniformity of the thickness of the rolled sheet. To solve this problem, it is necessary to add a complicated control system and investment.
In response to the above problems, four kinds of four-row tapered roller bearings with high dynamic load ratings were designed for domestic and foreign host users.

1. Selection analysis Four-row cylindrical and four-row tapered roller bearings capable of withstanding high rated loads are usually used for rolling mills and oil drilling rigs that are subjected to radial loads. However, in addition to large radial loads, these mainframes are often accompanied by small and indefinite axial loads. When four-row cylindrical roller bearings are selected, double-row tapered roller bearings should also be used for axial positioning and withstand small axial forces, which occupies the axial design space of the shaft and axle box, so that four The reduced axial (width) dimensions of the cylindrical roller bearings limit the design of the bearing's effective design space to maximize the bearing's rated load.
The four-row cylindrical roller bearing has no self-aligning properties, and it also has two major drawbacks: uneven force and the inability to adopt a sealing structure. Considering the convenience of installation and disassembly of the main machine, the four-row cylindrical roller bearing adopts the outer ring with the rib, the inner ring has no rib structure, and the inner ring is tightly sleeved on the journal, often from the bearing outer assembly mounted on the axle box. The push-in and pull-out are not possible, and the sealing structure cannot be used. The rolling mill bearing adopts four-row tapered roller bearing, which can overcome the drawbacks that the above four-row cylindrical roller bearing can only bear radial load. This eliminates the width of the double row tapered roller bearing or the radial thrust tapered roller bearing for axial positioning, which lengthens the roller and increases the rated load. In addition, the four-row tapered roller bearing also has a certain degree of self-aligning property, and is suitable for a sealing structure, thereby reducing grease consumption and reducing environmental pollution.
2. Four-row tapered roller bearings with high dynamic load rating are designed and developed with "rolling bearing limit design method". Ten kinds of four-row tapered roller bearings (see table) suitable for heavy load conditions are used for 6000~9000T rolling. The use of force rolling mills.