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Design and Safety Guidelines for Radial Cylindrical Roller Bearings

by:JNSN     2021-12-28
Design and safety guidelines Bearing capacity and working life using super-precision cylindrical roller bearings are usually used in the occasions with high load-bearing capacity, high rigidity and high precision requirements. In practice, it is rare for these bearings to fail due to fatigue. Therefore, the calculation of the rated life L10 according to DIN ISO 281 to determine the working life method is not accurate. Bearing equivalent static load The equivalent static load P0 is calculated based on the axial and radial loads of the bearing. Super-precision cylindrical roller bearings only support radial forces. For bearings subjected to static load, the following formula is used: P0 N bearing equivalent static load N bearing radial static load. Static load safety factor Whether the static load bearing capacity is sufficient for a given static load can be verified by the static load safety factor S0. S0 static load safety factor C0 N basic static load rating P0 N bearing equivalent static load. In order to take advantage of the high precision of the bearing, the static load safety factor S0 3 is necessary (S0 8 u003d anti-fatigue). Cylindrical roller bearing clearance adjustment Cylindrical roller bearings with a tapered bore can be installed in three situations with clearance, no clearance or preload. Please refer to the table on page 126. For vertical lathes, an interference of 5 m has proven effective. The limit speed nG given in the speed size table is only suitable for grease lubrication or minimum oil lubrication, and it is not allowed to exceed this speed. For cylindrical roller bearings, the achievable speed in motion is determined by the internal radial clearance, please refer to the table. Achievable speed dM u003d (d + D)/2 These values u200bu200bare guidelines when the temperature difference T between the inner and outer rings does not exceed 5 K. For applications with large temperature differences, please consult the Industrial Applications Department of the Schaeffler Group. Radial stiffness The radial stiffness cr is the ratio of the radial load to the radial displacement. cr N/ m radial stiffness, see dimension table Fr N radial force r radial displacement. The clearance or preload can reach the speed m min1 5 to 0 to 0.5 nG grease 2 105 dM 0.5 to 0.75 nG grease 4 105 dM 0.75 to 1 nG grease 1 104 dM 1 nG oil Bearing arrangement design In order to make full use of the performance of ultra-precision cylindrical roller bearings, adjacent structures must be properly designed, Figure 3. d u003d nominal diameter of the shaft d u003d diameter of the small end of the tapered shaft (u003d d + lower deviation, see table on page 129) d1 u003d diameter of the large end of the tapered shaft d1 u003d d + 1/12 · LL u003d cone Shaft length L u003d 0.95 · B (bearing width) t1 u003d Cylindricity conforms to DIN ISO 1101 t2 u003d Roundness conforms to DIN ISO 1101 t3 u003d Flatness conforms to DIN ISO 1101 t4 u003d Axial runout conforms to DIN ISO 1101 t5 u003d Coaxiality conforms DIN ISO 1101 ATD u003d Taper tolerance in accordance with DIN ISO 7178 Ra u003d Average surface roughness in accordance with DIN ISO 4768 Figure 3 Geometrical tolerances of shafts, machining tolerances of taper angles, Taper angle tolerances, ATD, measured perpendicular to the journal and defined as the differential diameter . If the taper measuring instrument MGK132 is used, the value of ATD in the table must be halved (inclination angle tolerance). For the taper shaft length table among the listed values, the taper angle tolerance ATD can be obtained by interpolation. Taper Deviation The taper angle deviation of the taper shaft mating surface, used for bearings with tolerance class SP, please refer to the table. The main dimensions of precision bearings comply with standard DIN 620-1. The dimensional tolerances and geometric tolerances conform to tolerance class SP. Super-precision cylindrical roller bearings with a higher tolerance class UP can also be provided through agreement. The bearings have cylindrical or tapered bores and have corresponding dimensional tolerances, see Figure 4 and the table on page 134. u003d Inclination angle of the cone end u003d 2° 23 9.4 2 u003d Cone angle of the cone end u003d 4° 46 18.8 B u003d Inner ring width d u003d Nominal diameter of the bearing bore d1 u003d Cone diameter dmp u003d Single The diameter deviation of the radial plane nominal diameter is shown in Figure 4 Tolerance of the tapered hole.
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