Clearance Adjustment Method of FAG Precision Cylindrical Roller Bearings
Cylindrical roller bearings with a tapered bore can be installed with positive clearance, zero clearance or preload (as shown in Table 8), and the FAG envelope circle measuring device can be accurate to 1 μm. In the following example, the installation of a tapered bore cylindrical roller bearing with removable outer ring (N10 and NN30) and a FAG MGA 31 enveloping circle gauge will be described. Enveloping circle gauges are used to precisely set the radial clearance or preload of cylindrical roller bearings. Use a conventional bore gauge to measure the raceway diameter of the outer ring (Figure 9). Transfer the measured diameter to the two hardened and ground surfaces of the enveloping circle gauge (Figure 10). Next, install the inner ring/roller assembly on the tapered shaft and place the envelope circle gauge on the assembly (Figure 11). Move the bearing axially on the shaft until the enveloping circle gauge shows the desired radial or negative clearance value. Then, measure the distance from the inner ring to the shoulder at 4 measuring points 90 apart on the circumference with a gauge block (Figure 12). Remove the bearing inner ring, grind the spacer to the distance determined above, and install it on the shaft. Finally, install the bearing inner ring again and lock it with a nut. If the above measuring equipment is not available, the clearance can also be adjusted more accurately by measuring the raised distance from the inner ring to the taper shaft (taper 1:12) shoulder end face. Mounting clearance/preload limiting speed single row cylindrical roller bearing 5 ... 0 [μm] 0.75 n* Grease lubricated 0 [μm] (zero clearance)) 0.75 ... 1.0 n* Grease lubricated 0 ... 5 [μm] 1 ... 1.1 n* Grease lubricated 0 ... 5 [μm] 1.0 n* Oil lubricated double row cylindrical roller bearing 5 ... 0 [μm] 0.50 n* Grease lubricated 2 10 5 dm [mm] 0.50 ... 0.75 n* Grease lubricated4 105 dm [mm] 0.75 ... 1.0 n* Grease lubricated1 104 dm [mm] 1.0 n* Oil lubricated* See bearing data table for limiting speeds dm u003d (d +D)/2 These values u200bu200bare used as reference values u200bu200bfor bearings with a temperature difference of T 5K between the inner and outer rings. When the temperature difference between the inner and outer rings is larger (electric spindle bearings), please consult Schaeffler. 8: Speed u200bu200bn of the cylindrical roller bearing. The lift distance is approximately 13 to 19 times the radial expansion (factor F). Surface finish, elastic expansion of the inner ring and shrinkage of the shaft all affect the F value. Refer to Table 13 to determine the coefficient F value. Lifting distance A u003d F GdB u003d inner diameter of hollow shaft d’ u003d shaft diameter in the middle of tapered shaft dB/d’ u003d ratio of hollow shaft to shaft diameter G u003d radial clearance change. Example: Cylindrical roller bearings should have zero clearance after installation. First, install the outer ring into the housing. Then, put the shaft with the inner ring into the bearing seat, and turn it slowly when putting it in to avoid scratches on the main shaft. Move the inner ring until the radial play reaches 20 μm, then slowly turn the spindle. The clearance measurement is carried out by moving the inner ring radially, eg by raising the main shaft, while holding the indicator near the bearing. Lifting distance A u003d coefficient F Radial clearance change G, example dB/d’ u003d 0.55, radial clearance change G u003d 20 μm Lifting distance A u003d 17 20 μm u003d 340 μmu003d 0.34 mm. Measure the axial distance between the inner ring and the adjacent shoulder. For example, use a gauge block to measure 4 points that differ by 90. Grind the spacer to the measurement and install against the shoulder. Finally install the bearing and check for zero clearance. When installing cylindrical roller bearings, as long as the inner ring is not tilted relative to the outer ring and the spindle rotates slowly during installation, no scratches will occur. It is best to simplify the installation process by heating the housing and outer ring. Installation according to the method described above can ensure that the clearance meets the requirements after installation, and the position of the inner ring will not change due to vibration during rotation.