DEVELOPMENT OF METHODS OF RELIABILITY ASSESSMENT FOR TURRET BALL BEARING RING OF A BMP-2 INFANTRY FIGHTING VEHICLE

A large part of BMP-2 Infantry Fighting Vehicles needs to replace turret ball bearing rings. Under realization of replacement of spare parts and components made in Russia with domestic ones, KNVO "Fort" MVO Ministry of Internal Affairs of Ukraine made an experimental batch of balls for turret ball bearing rings of infantry fighting vehicles BMP type. As a result of modernization of a turret ball bearing ring, steel balls were replaced with balls made of composite material. A turret ball bearing is a large radial thrust bearing, cages of which are turret races. A stabile lower race is fixed by means of screws to a top of the vehicle‟s hull. Above the fixed race there is a movable upper race to which the turret is bolted. A method for assessing the reliability of turret ball bearing rings of military armored vehicles was developed. The results of tests of turret ball bearing rings of BMP-2 infantry fighting vehicle tower are given. The reliability of turret ball bearing rings of armored vehicles was assessed taking into account the damage to the balls. The main types of damage to the balls: non-compliance of balls average diameter and non-compliance of the spherical shape of the ball to the requirements of operating documentation. The impact of the probability of no-failure operation of the balls on the durability of the ball bearing is determined. It is necessary to take into account the presence of damage to the balls when determining the durability of the ball bearing. To validate the adequacy of the method, it is necessary to increase the test time of the ball bearing by conducting tests during its operation.

Контроль натяга колец подшипников поверхностными волнами с использованием эффекта акустоупругости

In this paper, experimental and computational studies of the method of controlling the tension of bearing rings using the acoustoelasticity effect, based on measuring the characteristics of surface elastic waves propagating in a stressed medium, are carried out. Tuning samples of bearing rings tension on the axle neck of a freight car wheelset with an error of no more than 7 microns were developed and manufactured. Certification of a hydraulic stand for loading bearing rings, simulating their press fit on the axle, was performed. For surface waves, the acoustoelastic coefficient was measured by a Rayleigh wave pulse that repeatedly circled the ring. The correlation method for determining the delay time of a wave in a loaded ring relative to the unloaded one is optimized according to the condition of error minimization. The main reasons for the appearance of errors and uncertainties in the absolute time of propagation of a surface wave through the ring are considered: the influence of waves reflected from the boundaries, the curvature of the surface, and attenuation. The bearing ring tension was measured using the acoustoelasticity effect and the uncertainty of the stress measurement was estimated.

Assessment of Changes in Microstructure and Hardness of Bearing Steel for Operation at a High Temperature Caused by Short-Term Overheating

The paper presented research results of the impact of short-term overheating of samples collected from the outer bearing ring suitable for the operation at elevated temperature installed in the turbine engine on the microstructure and hardness of the material. The samples were annealed at the following temperatures: 500, 600, 700, 800, 900 and 1000°C; and then cooled in still air. Microstructure examinations were conducted under metallographic microscope and transmission electron microscope.