The Reliability Function of Case-Hardened Cylindrical Gears

An improved approach to the reliability function calculation of case-hardened spur and helical gears is presented in the paper. The calculation of the reliability function based on six possible gear failures is substantiated: the pitting of a pinion or wheel, the tooth breakage of a pinion or wheel, the tooth flank fracture of a pinion or wheel. The methodology for the reliability function calculation according to the criterion of surface durability (pitting) takes into account the random nature of the misalignment of the teeth in the mesh, caused by the deformation of the gear elements under the action of the transmitted torque (force misalignment). In the given method under the criterion of bending durability (tooth breakage), applied formulas allow calculating an allowable stress number for bending of the tooth through the parameters of the hardened case. Verification of the calculation formulas for the allowable stress number for bending, taking into account the parameters of the hardened case, was carried out according to the experimental data. The calculation methods analysis of deep equivalent stresses is carried out by the authors. The accuracy of the hardness depth profiles (carbonization, carbonitriding) is estimated. The technique has been developed for the reliability function calculation of case-hardened gears according to the criterion of deep equivalent durability. The verification of the developed methods for calculating the reliability function according to the operation data of case-hardened gears is performed.