1. Structural composition and characteristics
Two-way double-row thrust cylindrical roller bearings, which are separable bearings, are composed of shaft rings, housing rings, clearance spacer rings, two-row circular rolling elements and cage components, mainly used in steel rolling mills as auxiliary bearings and multi-row cylindrical roller bearings (four-row cylinders), used to bear all the axial forces generated during steel rolling, so as to limit the two-way axial displacement of the shaft, prevent the relative displacement of the upper and lower rolls and the dislocation of the slots, so as to ensure the morphological specifications of the rolled products. 
Since bi-directional thrust tapered roller bearings are usually mounted loosely on the roll journal and roll housing, most bearings have one or two locating grooves in the housing ring. In this way, it is possible to use a key embedded in the positioning groove or a similar method to prevent the shaft seat ring from rotating on the shaft, the bearing does not have self-aligning performance, is more sensitive to misalignment, does not allow the shaft to tilt with the shaft of the shell after installation, and a large angular alignment error will produce additional stress, which will shorten the service life of the bearing.
2. Bearing clearance value setting
There is a clearance adjustment ring held in the middle of the seat ring in the structural composition, so the axial clearance of the bearing has been adjusted to a fixed value at the factory, and if the customer needs to adjust it in the process of use, the clearance value can be adjusted by increasing the height and shortening the height of the clearance adjustment ring. At the same time, due to the limitation of the bearing structure and the characteristics of low ultimate speed, the bearing is mainly used in the billet opener, rough rolling and middle rolling part of the long product rolling mill, and the bearing mainly bears the axial load and limits the two-way axial displacement of the shaft, so as to prevent the relative displacement of the upper and lower rolls and the dislocation of the slots, so as to ensure the shape specification of the rolled product. The size of the axial clearance determines the relative channeling momentum of the roll and the amount of slot dislocation, which affects the subsequent rolling process and the quality of the finished product, so the setting of the axial clearance value is particularly critical
Table 1 Recommended axial clearance values for bidirectional thrust tapered roller bearings in long product mills
Note: For clearance adjustment, please contact DMD Technical Department
3. Precautions for installation
The three dimensions of two-way thrust tapered roller bearings: DXDXH are all national standard sizes, and there will generally be no improper fit or error in design selection or installation, but the D1 value and DC value, that is, the inner diameter of the seat ring and the inner diameter of the cage assembly, multiple models involve a variety of sizes and the size of each factory standard in the improvement and optimization is not consistent with each other, which often leads to the problem of DC value and the outer diameter of the shoulder or sleeve during installation, so the D1 value must be considered together in the design, selection or installation. DC value to avoid installation interference issues. 
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