Cylindrical roller bearing installation, fit, clearance adjustment and installation
Installation: Cylindrical roller bearings can be installed separately, but they are usually used in conjunction with another cylindrical roller bearing, spherical roller bearing or tapered roller bearing. Figure 8 shows a coal mill grinding roller that uses a combination of double row spherical roller bearings and a row of cylindrical roller bearings. Cylindrical roller bearings in this application allow the shaft to float relative to the housing. Figure 9 shows a one-stage reducer with herringbone teeth. The input shaft is equipped with a row of tapered roller bearings and a row of cylindrical roller bearings. Two rows of cylindrical roller bearings are installed on the output shaft. Fitting: Tables 6 to 18 on pages 22 to 33 provide recommendations for the fit of cylindrical roller bearings. It is mainly based on the following conditions: The bearing is of ordinary accuracy grade. The bearing seat is thick and made of steel or cast iron. The shaft is a solid shaft and made of steel. The bearing mating surface is ground and the surface roughness is lower than 1.6um Ra. Suggested fitting symbols Comply with ISO 286 standard. If you need advice on the amount of coordination, please contact your t Timken representative. Figure 8. Coal pulverizer grinding roller diagram 9. The cylindrical roller bearing installation, fit, clearance adjustment and installation warning of the first-stage reducer. Correct maintenance and operation are very important. Always follow the installation instructions and maintain proper lubrication. It is strictly forbidden to rotate the bearing with compressed air, which may cause the bearing parts to eject at high speed. Failure to observe the following warning information may result in serious personal injury or death. Thermal gradient: The thermal gradient in the bearing is a function of the bearing speed. When accelerating, the thermal gradient also rises, the heat increases, and the radial clearance decreases. According to experience, when the actual speed exceeds 70% of the rated speed, the radial clearance should be increased. Please consult your Timken representative to choose the correct diameter. Clearance to the inside. Table 5 lists the radial internal clearance tolerances. Standard or non-standard radial internal clearance is specified when ordering cylindrical roller bearings. The standard radial internal clearance is C2, C0 (standard), C3, C4 or C5, which conforms to the ISO5753 standard. C2 represents the minimum clearance, and C5 represents the maximum clearance. Non-standard clearance can be provided according to specific requirements. The radial clearance is determined according to the required operating accuracy, bearing speed and matching amount of the application. Most applications choose standard clearance or C3 clearance. Larger clearances generally reduce the bearing area of u200bu200bthe bearing, increase the maximum roller load, and shorten the expected life of the bearing. However, the cylindrical roller bearing in the preloaded state may be scrapped prematurely due to excessive heat generation or material fatigue damage. A basic principle is that cylindrical roller bearings should avoid running under negative clearance. As a basic principle, the rotating inner ring should be an interference fit. Loose fit will cause the inner ring to skid and cause wear on the shaft and shaft shoulder. Such wear will cause the bearing assembly to be too loose and damage the bearing and shaft. In addition, metal abrasive particles generated by the inner ring running laps may enter the bearing and cause bearing damage or vibration. The fitting amount of the stationary inner ring depends on the load situation of the application. Use load conditions and bearing dimensions to select the shaft fit recommended in the table. Similarly, the application of outer ring rotation should make an interference fit between the outer ring and the bearing seat. The stationary outer ring usually adopts a loose fit to facilitate installation and disassembly. Thin-walled housings, light alloy housings, or hollow shafts must use a tighter interference fit than thick-walled housings, steel/cast iron housings, or solid shafts. When the bearing is installed on a relatively rough or unpolished surface, a tight fit is also required. Clearance adjustment: In order to obtain a suitable operating clearance, attention must be paid to the influence of the amount of fit and the effect of the thermal gradient of the bearing. Fit: The interference fit between the inner ring and the solid steel shaft will reduce the radial clearance in the bearing by approximately 85% of the fit. The interference fit between the outer ring and the steel or cast iron housing will reduce the radial clearance by approximately 60% of the fit.