Research on the influencing factors of thermal characteristics of high-speed grease lubricated angular contact ball bearing

The high temperature rise of grease lubricated angular contact ball bearing under high speed operation will affect the working accuracy of the bearing, and even lead to the loss of accuracy. In this paper, a friction heat generation model for high-speed grease lubricated angular contact ball bearing was established. Based on the quasi-static analysis model, the thermal expansion of the bearing components is brought into the quasi-static equilibrium equation, and the modified quasi-static analysis model of high-speed grease lubricated ACBB is obtained. Under grease lubrication conditions, a local bearing heat-generation model was employed to assess power losses in different contact zones, in which bearing contact parameters, external loads, and rotation speeds conditions were fully considered. Moreover, the temperature distribution of grease lubricated high-speed bearing was analyzed by the multi node thermal network method. Through the analysis model of bearing dynamic and thermal characteristics considering the influence of thermal expansion established, bearing contact parameters have significant differences. The calculated values of outer ring temperature of grease lubricated angular contact ball bearing is in good agreement with the experimental values. The model can predict the temperature values of grease lubricated angular contact ball bearing under axial load at high speed.

Experimental Investigations to Analyze Surface Contact Fatigue Wear by Using a Dynamic Response of the Roller Bearing System

Bearings are used to reduce friction between two rolling /sliding members of the machines. Under normal operating conditions, an increase in the fatigue load cycles on the bearing contact surfaces results in surface defects viz. micro pitting, macro pitting, spalling and scuffing, thereby causing lubricant degradation. Hence, to maintain a better operating performance of rotating machines, it is essential to keep track of operating parameters. This paper describes the results of experimental investigations carried out to assess wear propagation on bearing contact surfaces using tribological and vibration parameters. Results obtained from experimental investigations provide a good correlation between the increase in surface fatigue wear and corresponding effects on transition in lubrication regimes, increased vibration levels, variations in rheological properties of lubricant and wear mechanisms developed on the contact surfaces of the roller bearing. The proposed approach can be used as a promising tool to assess incipient faults developed in roller bearing.

Software Application for Design of Straight Bevel Gear with Localization of Bearing Contact

Разработан программный комплекс для проектирования прямозубых конических передач с локализованным контактом. Предложена методика построения 3D-моделей активных поверхностей зубьев, обеспечивающая получение требуемой локализации контакта. Одно из колес передачи выполнено с эвольвентными прямыми зубьями. Выбор боковых поверхностей зубьев сопряженного колеса для реализации локализованного контакта осуществляется на основе решения задачи условной оптимизации. Представлен алгоритм оценки характеристик зацепления и контакта в модифицированной передаче. Целевой функцией, подлежащей минимизации, является максимальное контактное давление в период работы одной пары зубьев. Варьируемыми являются параметры синтеза, определяющие положение центра локализованного пятна контакта и его размеры. Ограничением при решении задачи выступает предотвращение кромочного контакта. Предложен итерационный эвристический алгоритм для решения задачи минимизации целевой функции. В начале работы алгоритма выбирается начальная точка. На каждой итерации с некоторым шагом рассчитываются несколько точек кандидатов для следующего начального приближения. Переход совершается в ту точку с наименьшим значением целевой функции, где отсутствует кромочный контакт. При невозможности перехода уменьшается шаг для расчета точек-кандидатов. Алгоритм завершает работу при невозможности найти подходящую точку или слишком малом шаге. Дан пример расчета.

Failure Life Prediction of Hub Bearing in Composite Tooling

Composite work tools have many components, and complex shapes when compared to standard tools such as rotaries and plows. In addition, the component durability for the tools is critical because the load varies severely according to the soil conditions. This study predicts the fatigue life of the hub bearing in composite work tooling. The loads acting on the tools were measured based on field tests, and the loads acting on the hub bearing were derived using the load reconstruction method. The static safety factor and fatigue life of the hub bearing, loads, and contact stress acting on the inner and outer raceways and presence of truncation were analytically predicted based on the derived loads. The fatigue life of the bearing changed depending on the preload amount of the hub bearing. The bearing life was more than 3000 h for preloads of less than 40 μm, which satisfied the target life of 1200 h. The load acting on the inner and outer raceways of the bearing decreased and then increased as the preload amount of the bearing rose. The bearing contact area, maximum contact stress, and number of balls increased as the load applied to the hub bearing rose. The fatigue life, load, contact stress, and static safety factor of the hub bearing met all requirements, and no truncation occurred on the inner and outer raceways of the bearing. The test verified the achievement of the target life of 1200 h and confirmed that there was no breakage, cracking, or deformation of the bearing.

Study on the influence of round pits arrangement patterns on tribological properties of journal bearings

Purpose The purpose of this paper is to investigate the effect of round pits arrangement patterns on tribological properties of journal bearing. In this paper, the tribological behaviors of journal bearing with different arrangement patterns under lubrication condition were studied based on M-2000 friction and wear tester. Design/methodology/approach The friction and wear of journal bearing contact surface were simulated by ANSYS. The wear mechanism of bearing contact surfaces was investigated by the means of energy dispersive spectrum analysis on the surface morphology and friction and wear status of the journal bearing specimens by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). Besides, the wearing capacity of the textured bearing was predicted by using the GM (1,1) and Grey–Markov model. Findings As the loads increase, the friction coefficient of journal bearing specimens decrease first and then increase slowly. The higher rotation speed, the lower friction coefficient and the faster temperature build-up. The main friction method of the bearing sample is three-body friction. The existence of texture can effectively reduce friction and wear. In many arrangement patterns, the best is 4# bearing with round pits cross-arrangement pattern. Its texturing diameters are 60 µm and 125 µm, and the spacing and depth are 200 µm and 25 µm, respectively. In addition, the Grey–Markov model prediction result is more accurate and fit the experimental value better. Originality/value The friction and wear mechanism is helpful for scientific research and engineers to understand the tribological behaviors and engineering applications of textured bearing. The wear capacity of textured bearing is predicted by using the Grey–Markov model, which provides technical help and theoretical guidance for the service life and reliability of textured bearing.