Lubricants

Research

17 pages, 11753 KiB

Open AccessArticle

Thermal Dynamic Exploration of Full-Ceramic Ball Bearings under the Self-Lubrication Condition

by Junxing Tian, Yuhou Wu, Jian Sun, Zhongxian Xia, Kexuan Ren, He Wang, Songhua Li and Jinmei Yao

Lubricants 2022, 10(9), 213; https://doi.org/10.3390/lubricants10090213 - 6 Sep 2022

Cited by 15 | Viewed by 3118

Abstract

A silicon nitride ceramic bearing has good self-lubricating characteristics. It still has a good operational status under the condition of a lack of oil. However, the temperature distribution of a silicon nitride ceramic bearing during its operation is unclear. To clarify the thermal [...] Read more.

A silicon nitride ceramic bearing has good self-lubricating characteristics. It still has a good operational status under the condition of a lack of oil. However, the temperature distribution of a silicon nitride ceramic bearing during its operation is unclear. To clarify the thermal distribution of a full-ceramic ball silicon nitride ceramic bearing under self-lubricating conditions, the changing trend of the rolling friction temperature between the rolling elements and channels with different accuracies is analyzed using the friction testing machine. The bearing heat generation model based on the silicon nitride material coefficient is established, and the life test machine measures the temperature of the bearing to verify the accuracy of the simulation model. The results show that the friction temperature between the ceramic ball and channel decreases with the increase in ceramic ball level. With an increase in the ceramic ball pressure and temperature, the friction temperature rises. Under self-lubrication, when the bearing bears a heavy load, the influence of the rotating speed on temperature rise tends to decrease. Under the condition of high speed, with the increase in load, the change range of temperature rise shows an upward trend. The important relationship between the bearing’s heat and bearing’s load and speed is revealed. It provides some theoretical guidance for the thermal analysis of a silicon nitride ceramic ball bearing under the self-lubricating condition to improve the service life and reliability of full-ceramic ball bearings. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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14 pages, 3757 KiB

Open AccessFeature PaperArticle

The Influence of Bearing Ring Inclination on Precision Ball Bearing Contact and Heat Generation Performance

by Bei Yan, Xiaohong Zhang and Zanfei Zhu

Lubricants 2022, 10(9), 206; https://doi.org/10.3390/lubricants10090206 - 29 Aug 2022

Cited by 2 | Viewed by 3098

Abstract

The assembly quality between bearing components will lead to an increase in the load imbalance of each rolling element, which becomes a factor that affects the heat generation of precision bearings. The motion and heat generation of angular contact ball bearing (ACBB) under [...] Read more.

The assembly quality between bearing components will lead to an increase in the load imbalance of each rolling element, which becomes a factor that affects the heat generation of precision bearings. The motion and heat generation of angular contact ball bearing (ACBB) under different assembly states were studied, and the quasi-static model of ACBB with outer ring tilting was established. The contact angle, contact load and motion posture of rolling elements were obtained. Then, the relative imbalance of the outer ring was experimentally simulated based on the outer spacer ring with poor end-parallelism, and the thermal characteristics of the spindle system were monitored. Through theoretical and experimental comparison, the influence of different skew degrees of rings on bearing heat generation and spindle rotation accuracy was discussed. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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19 pages, 10022 KiB

Open AccessArticle

Research on the Bearing Sliding Loss Based on Time-Varying Contact Angle between Ball and Raceway

by Shuaijun Ma, Ke Yan, Mengnan Li, Yongsheng Zhu and Jun Hong

Lubricants 2022, 10(8), 185; https://doi.org/10.3390/lubricants10080185 - 15 Aug 2022

Cited by 4 | Viewed by 2909

Abstract

Based on the mechanical model, the friction loss between the ball and the raceway along the major axis of the contact ellipse is analyzed. The result shows that this part of the loss accounts for about 13.67% of the overall loss, which is [...] Read more.

Based on the mechanical model, the friction loss between the ball and the raceway along the major axis of the contact ellipse is analyzed. The result shows that this part of the loss accounts for about 13.67% of the overall loss, which is mainly determined by the ball sliding length and cannot be ignored. The effects of the radial force, torque, rotational speed and groove curvature ratio on the sliding are all studied. Compared with other factors, radial force has the greatest influence on the sliding loss. As bearing speed gradually grows, the sliding on the inner raceway gradually increases while it gradually decreases on the outer raceway. Compared to the outer raceway curvature ratio, the sliding length is less sensitive to changes in the curvature ratio of the inner raceway. The paper provides theoretical guidance for the design and application of low-friction bearings. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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12 pages, 5326 KiB

Open AccessArticle

Flow Mechanisms and Lubrication Performance of Water-Lubricated Thrust Bearings with Herringbone Grooves

by Haifeng Ran, Peng Dai, Shuping Yan, Fengtao Wang, Xingjia Yao, Jianping Wang and Guizhong Zuo

Lubricants 2022, 10(8), 182; https://doi.org/10.3390/lubricants10080182 - 10 Aug 2022

Cited by 7 | Viewed by 2479

Abstract

Due to their excellent stability and zero leakage capability, thrust bearings with herringbone spiral grooves are frequently used in transmission mechanisms. However, the lubrication mechanism of thrust bearings has not been clearly understood and explained, preventing the optimization of the bearing performance. Thus, [...] Read more.

Due to their excellent stability and zero leakage capability, thrust bearings with herringbone spiral grooves are frequently used in transmission mechanisms. However, the lubrication mechanism of thrust bearings has not been clearly understood and explained, preventing the optimization of the bearing performance. Thus, this paper is devoted to solving this problem by building a three-dimensional finite element flow model. In this model, the change in viscosity temperature is considered using Roelands equation, and the turbulence and cavitation are taken into consideration. Using the established model, the influence of parameters such as spiral angle, groove width ratio, and rotational speed on the cavitation area of the thrust bearing are analyzed. The pressure contour and speed distribution are obtained inside the clearance, as well as the volume fraction of the gas phase at the end face. Finally, according to the analysis results, the optimum structural parameter for the herringbone spiral groove structure is proposed, which enables higher bearing stability and provides a reference for engineering practice. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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20 pages, 5830 KiB

Open AccessArticle

Study on Distribution of Lubricating Oil Film in Contact Micro-Zone of Full Ceramic Ball Bearings and the Influence Mechanism on Service Performance

by Jinmei Yao, Yuhou Wu, Jiaxing Yang, Jian Sun, Zhongxian Xia, Junxing Tian, Zhigang Bao and Longfei Gao

Lubricants 2022, 10(8), 174; https://doi.org/10.3390/lubricants10080174 - 1 Aug 2022

Cited by 4 | Viewed by 2877

Abstract

Compared with metal ball bearings, full ceramic ball bearings have more outstanding service performance under extreme working conditions. In order to reveal the lubrication mechanism and improve the operation performance and service life of full ceramic ball bearings, in this paper, the friction, [...] Read more.

Compared with metal ball bearings, full ceramic ball bearings have more outstanding service performance under extreme working conditions. In order to reveal the lubrication mechanism and improve the operation performance and service life of full ceramic ball bearings, in this paper, the friction, vibration, and temperature rise characteristics of 6208 silicon nitride full ceramic deep groove ball bearing, under the condition of oil lubrication, are studied experimentally. Based on the test results, and through theoretical calculation and simulation analysis, the distribution of the lubricating oil film in bearing contact micro-zone under different working conditions was simulated. After that, the surface of contact micro-zone of full ceramic ball bearing was analyzed. It was found that there is an optimal oil supply for full ceramic ball bearing oil lubrication in service. Under the optimal oil supply lubrication, full film lubrication can be achieved, and the bearing exhibits the best characteristics of friction, vibration, and temperature rise. Compared with the load, the rotational speed of the bearing has a decisive influence on the optimal oil supply. When the rotational speed and load are constant, the minimum oil film thickness and oil film pressure in the contact area of the rolling body decrease with the increase of angle ψ from the minimum stress point of the rolling body. Under the action of high contact stress, thin oil film will be formed in the bearing outer ring raceway. In the field of full ceramic ball bearings, the research content of this paper is innovative. The research results of this paper have an important guiding significance for revealing the oil lubrication mechanism of full ceramic ball bearing and enriching its lubrication theory and methods. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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19 pages, 6600 KiB

Open AccessArticle

Prediction of Remaining Service Life of Rolling Bearings Based on Convolutional and Bidirectional Long- and Short-Term Memory Neural Networks

by Zhidan Zhong, Yao Zhao, Aoyu Yang, Haobo Zhang and Zhihui Zhang

Lubricants 2022, 10(8), 170; https://doi.org/10.3390/lubricants10080170 - 26 Jul 2022

Cited by 10 | Viewed by 2451

Abstract

Predicting the remaining useful life (RUL) of a bearing can prevent sudden downtime of rotating machinery, thereby improving economic efficiency and protecting human safety. Two important steps in RUL prediction are the construction of a health indicator (HI) and the prediction of life. [...] Read more.

Predicting the remaining useful life (RUL) of a bearing can prevent sudden downtime of rotating machinery, thereby improving economic efficiency and protecting human safety. Two important steps in RUL prediction are the construction of a health indicator (HI) and the prediction of life. Traditional methods simply use the time-series characteristics of the vibration signal, for example, using root mean square (RMS) as HI, but this HI does not reflect the true degradation of the bearing. Meanwhile, existing prediction models often cannot consider both the time and space characteristics of the signal, thus limiting prediction accuracy. To address the above problems, in this study, wavelet packet transform (DWPT) and kernel principal component analysis (KPCA) were combined to extract HI from the original vibration signal. Then, a CNN-BiLSTM (convolutional and bidirectional long- and short-term memory) prediction network with root mean square as input and HI as output was constructed by combining convolutional neural network (CNN) and bi-directional long- and short-term memory neural network (BiLSTM). The network improved prediction accuracy by considering the temporal and spatial characteristics of the input signal. Experimental results on the PHM2012 dataset showed that the method proposed in this paper outperformed existing methods. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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12 pages, 2484 KiB

Open AccessArticle

An Investigation for the Friction Torque of a Tapered Roller Bearing Considering the Geometric Homogeneity of Rollers

by Yuwei Liu, Xingyu Fan, Jia Wang and Xiayi Liu

Lubricants 2022, 10(7), 154; https://doi.org/10.3390/lubricants10070154 - 12 Jul 2022

Cited by 5 | Viewed by 3890

Abstract

The geometric homogeneity of rollers, namely the dimension and shape deviations among rollers in a roller bearing, is one of the most important manufacturing errors. However, to the best of the authors’ knowledge, no specified investigation has been carried out on the effects [...] Read more.

The geometric homogeneity of rollers, namely the dimension and shape deviations among rollers in a roller bearing, is one of the most important manufacturing errors. However, to the best of the authors’ knowledge, no specified investigation has been carried out on the effects of the geometric homogeneity of rollers on the friction torque of tapered roller bearings (TRBs). By introducing the diameter deviation of rollers and the distribution form of rollers with a diameter deviation, this study presents a mathematic model to reveal the effects of the geometric homogeneity of rollers on the friction torque of TRBs. The geometric homogeneity of the rollers, although having only a minimal influence on the overall friction torque acting on rings, can lead to a significant increase in the slide friction force between the individual rollers and the inner raceway. By comparing the distribution form of rollers with a diameter deviation, the diameter deviation value of the roller shows a significant influence on the maximum sliding friction between the roller and the inner raceway. The impact of the geometric homogeneity of rollers on the sliding friction between the roller and the inner raceway is more pronounced under light load conditions. The above-mentioned comparisons and conclusions can be used in formulating machining error criteria for TRB rollers. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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18 pages, 7900 KiB

Open AccessArticle

Dynamic Performance Analysis of Cage in Four-Point Contact Ball Bearing

by Yeteng Li, Wenchao Li, Yongsheng Zhu, Gaobo He, Shuaijun Ma and Jun Hong

Lubricants 2022, 10(7), 149; https://doi.org/10.3390/lubricants10070149 - 11 Jul 2022

Cited by 8 | Viewed by 3641

Abstract

Due to the special structure of double-half inner rings, four-point contact ball bearings are prone to uneven forces in the inner raceway during movement, which affects the dynamic performance of the rolling element and cage, and even leads to cage sliding. Dynamic performance [...] Read more.

Due to the special structure of double-half inner rings, four-point contact ball bearings are prone to uneven forces in the inner raceway during movement, which affects the dynamic performance of the rolling element and cage, and even leads to cage sliding. Dynamic performance of the cage is an important factor affecting the working stability of bearings. In this paper, in order to grasp the operation law of the cage so as to guide the application of four-point contact ball bearings, the dynamic model of four-point contact ball bearings is established by the secondary development of Automatic Dynamic Analysis of Mechanical Systems (ADAMS). The dynamic performance of the cage is analyzed and evaluated with the indexes of vortex radius ratio and vortex velocity deviation ratio of the cage centroid trajectory. The results show the following: the cage stability increases and then decreases to a certain degree with rotating speed-rise; it increases and then decreases with the increase in the pure axial load; under a combination of axial and radial load, the cage moves more smoothly with smaller radial force. Rotating speed has little effect on cage stability, while radial force has a great influence on cage stability, followed by axial load. In order to verify the simulation results, a test bench for rolling bearing cages is developed, and the accuracy of the simulation results is verified by the test results. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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14 pages, 5205 KiB

Open AccessArticle

Research on the Effect of Spindle Speed on the Softening and Hardening Characteristics of the Axial Operating Stiffness of Machine Tool Spindle

by Jiandong Li, Qiang Wang, Xurui Sun, Jue Qu, Ang Qiu, Wei Kang and Shuaijun Ma

Lubricants 2022, 10(7), 132; https://doi.org/10.3390/lubricants10070132 - 22 Jun 2022

Cited by 3 | Viewed by 1940

Abstract

Spindle stiffness is one of the most critical indicators for evaluating and measuring the service performance of spindles. The traditional static stiffness indexes only involve static analysis and rarely focus on the study of spindle-carrying capacity under operating conditions. In this paper, the [...] Read more.

Spindle stiffness is one of the most critical indicators for evaluating and measuring the service performance of spindles. The traditional static stiffness indexes only involve static analysis and rarely focus on the study of spindle-carrying capacity under operating conditions. In this paper, the explicit solution approach is used to develop a mechanical model of the spindle’s axial operating stiffness. This model was then used to explore the influence of rotational speed on the softening and hardening features of the spindle axial operating stiffness, and experimental verification was carried out. According to studies, the speed of a fixed-position preload spindle can lead its operating stiffness to exhibit a “stiffness-hardening” feature. However, when the axial displacement of the spindle is small, the operating stiffness curve of the spindle displays a noticeable “fluctuation” phenomenon for low-speed spindles. Furthermore, the speed-induced preload has a significant impact on the test results when testing spindle axial operating stiffness. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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16 pages, 10532 KiB

Open AccessArticle

Research on the Mechanism of the Stiffness Performance of Rolling Bearings under Wrong Assembly State

by Yanfei Zhang, Yunhao Li, Lingfei Kong, Zhenchao Yang and Yue Si

Lubricants 2022, 10(6), 116; https://doi.org/10.3390/lubricants10060116 - 5 Jun 2022

Cited by 2 | Viewed by 2963

Abstract

In this paper, a quasi-static angular contact ball bearing model, considering assembly accuracy is constructed, while a numerical solution method for bearing stiffness under bad assembly state is established. A 7014C angular contact ball bearing is used as the research object and five [...] Read more.

In this paper, a quasi-static angular contact ball bearing model, considering assembly accuracy is constructed, while a numerical solution method for bearing stiffness under bad assembly state is established. A 7014C angular contact ball bearing is used as the research object and five groups of different spacer inclinations are designed to imitate the installation error of the spindle bearing. The bearing stiffness performance was comparatively analyzed, according to the five spacers. The effect of preload and rotation speed on bearing stiffness are systematically investigated, considering different parallelism errors, as induced by the spacers. The influence mechanism of the badly assembled bearing on the respective stiffness anisotropy is studied based on the proposed model. The results show that the variations of the inclination between the inner and outer rings of the bearing exhibit a very weak effect on the axial stiffness, while the influence on the radial and angular stiffness is more significant. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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20 pages, 3526 KiB

Open AccessArticle

Thermal Analysis Based on Dynamic Performance of Rocker Arm Full-Type Needle Bearings

by Guangtao Zhang, Bing Su, Fengbo Liu, Wenhu Zhang and Haisheng Yang

Lubricants 2022, 10(5), 104; https://doi.org/10.3390/lubricants10050104 - 23 May 2022

Cited by 3 | Viewed by 2561

Abstract

Based on a dynamic analysis of rolling bearings, the equations for rocker arm full-type needle bearings were established by considering the traction coefficients of FVA-M reference lubricating oil, and then they were solved by the GSTIFF (Gear Stiff) integer algorithm with variable steps. [...] Read more.

Based on a dynamic analysis of rolling bearings, the equations for rocker arm full-type needle bearings were established by considering the traction coefficients of FVA-M reference lubricating oil, and then they were solved by the GSTIFF (Gear Stiff) integer algorithm with variable steps. The influence of working conditions on friction power consumption and the lubricant’s convective coefficients were investigated. Then, on the basis of the heat generation and heat transfer mechanisms, the frictional power consumption was used as the boundary condition of the bearings’ simulation model. Finally, temperature fields were calculated by the finite element method. The results showed that the overall value of frictional power consumption increased gradually with the increase in either the radial load or the rotation speed. The presence or absence of lubricating oil film in the contact area affected the heat conduction of the bearing, resulting in a temperature difference. Compared with the temperature of the radial load exerted on the bearing, the maximum temperature was more sensitive to the variations in the rotation speed. When running under the conditions of a fatigue life test, the steady-state temperature value of the bearing gradually decreased from the outer raceway to the needle roller and the outer ring surface, and then to the central shaft. The maximum temperature rise was 25.9 °C relative to the ambient temperature. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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14 pages, 4016 KiB

Open AccessArticle

Hard Negative Samples Contrastive Learning for Remaining Useful-Life Prediction of Bearings

by Juan Xu, Lei Qian, Weiwei Chen and Xu Ding

Lubricants 2022, 10(5), 102; https://doi.org/10.3390/lubricants10050102 - 21 May 2022

Cited by 6 | Viewed by 2661

Abstract

In recent years, deep learning has become prevalent in Remaining Useful-Life (RUL) prediction of bearings. The current deep-learning-based RUL methods tend to extract high dimensional features from the original vibration data to construct the Health Indicators (HIs), and then use the HIs to [...] Read more.

In recent years, deep learning has become prevalent in Remaining Useful-Life (RUL) prediction of bearings. The current deep-learning-based RUL methods tend to extract high dimensional features from the original vibration data to construct the Health Indicators (HIs), and then use the HIs to predict the remaining life of the bearings. These approaches ignore the sequential relationship of the original vibration data and seriously affect the prediction accuracy. In order to tackle this problem, we propose a hard negative sample contrastive learning prediction model (HNCPM) with encoder module, GRU regression module and decoder module, used for feature embedding, regression RUL prediction and vibration data reconstruction, respectively. We introduce self-supervised contrast learning by constructing positive and negative samples of vibration data rather than constructing any health indicators. Furthermore, to avoid the subtle variability of vibration data in the health stage to aggravate the degradation features learning of the model, we propose the hard negative samples by cosine similarity, which are most similar to the positive sample. Meanwhile, a novel infoNCE and MSE-based loss function is derived and applied to the HNCPM to simultaneously optimize a lower bound on mutual information of the positive and negative sample over life cycle, as well as the discrepancy between true and predicted values of the vibration data, such that the model can learn the fine-grained degradation representations by predicting the future without any HIs as labels. The HNCPM is validated on the IEEE PHM Challenge 2012 dataset. The results demonstrate that the prediction performance of our model is superior to the state-of-the-art methods. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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25 pages, 38558 KiB

Open AccessArticle

A Novel Model for Evaluating the Operation Performance Status of Rolling Bearings Based on Hierarchical Maximum Entropy Bayesian Method

by Liang Ye, Yusheng Hu, Sier Deng, Wenhu Zhang, Yongcun Cui and Jia Xu

Lubricants 2022, 10(5), 97; https://doi.org/10.3390/lubricants10050097 - 13 May 2022

Cited by 2 | Viewed by 1969

Abstract

Information such as probability distribution, performance degradation trajectory, and performance reliability function varies with the service status of rolling bearings, which is difficult to analyze and evaluate using traditional reliability theory. Adding equipment operation status to evaluate the bearing operation performance status has [...] Read more.

Information such as probability distribution, performance degradation trajectory, and performance reliability function varies with the service status of rolling bearings, which is difficult to analyze and evaluate using traditional reliability theory. Adding equipment operation status to evaluate the bearing operation performance status has become the focus of current research to ensure the effective maintenance of the system, reduce faults, and improve quality under the condition of traditional probability statistics. So, a mathematical model is established by proposing the hierarchical maximum entropy Bayesian method (HMEBM), which is used to evaluate the operation performance status of rolling bearings. When calculating the posterior probability density function (PPDF), the similarities between time series regarded as a weighting coefficient are calculated using overlapping area method, membership degree method, Hamming approach degree method, Euclidean approach degree method, and cardinal approach degree method. The experiment investigation shows that the variation degree of the optimal vibration performance status can be calculated more accurately for each time series relative to the intrinsic series. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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13 pages, 4734 KiB

Open AccessArticle

Rheological and Frictional Properties of Lithium Complex Grease with Graphene Additives

by Yanshuang Wang, Xudong Gao, Jianghai Lin and Pu Zhang

Lubricants 2022, 10(4), 57; https://doi.org/10.3390/lubricants10040057 - 1 Apr 2022

Cited by 15 | Viewed by 3187

Abstract

Few-layer graphene (FLG) was added as a nano-additive to lithium complex grease (LCG) to explore the influence of FLG on the microstructure, viscoelasticity, friction and wear properties of LCG. Studies have found that the addition of FLG makes the microstructure of the thickener [...] Read more.

Few-layer graphene (FLG) was added as a nano-additive to lithium complex grease (LCG) to explore the influence of FLG on the microstructure, viscoelasticity, friction and wear properties of LCG. Studies have found that the addition of FLG makes the microstructure of the thickener more compact, which in turn leads to an increase in the viscoelasticity of LCG. FLG additives can improve the viscosity-temperature properties of the grease and change the elastic deformation response to temperature changes. Among the temperatures selected in this article, the effect of graphene is more obvious at 70 °C. During the friction process, a proper amount of FLG can quickly form a boundary film and is not easily damaged, thereby optimizing the friction and wear performance of LCG. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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10 pages, 3946 KiB

Open AccessArticle

Analysis of Grooves Used for Bearing Lubrication Efficiency Enhancement under Multiple Parameter Coupling

by Chao Wang, Mingkai Wang and Linbo Zhu

Lubricants 2022, 10(3), 39; https://doi.org/10.3390/lubricants10030039 - 7 Mar 2022

Cited by 2 | Viewed by 3073

Abstract

Adding axial groove structures to the surface of bearing inner ring is an effective way to enhance the bearing lubrication efficiency. In this paper, the angular contact ball bearing H7006C was taken as the research object, and through visual simulations and quantitative experiments, [...] Read more.

Adding axial groove structures to the surface of bearing inner ring is an effective way to enhance the bearing lubrication efficiency. In this paper, the angular contact ball bearing H7006C was taken as the research object, and through visual simulations and quantitative experiments, systematic analyses and discussions were carried out to find out the relationship between groove-enhancing performance and working conditions. Firstly, simulation models of standard bearing and groove-added bearing were established. By combining the Volume of Fluid (VOF) model, the enhancing mechanism of grooves was found. Secondly, the trend of groove-enhancing performance with the change of rotation speed was studied through simulations and quantitative experiments. On this basis, through multiple parameter coupling, the effects of oil supply amount and nozzle diameter on the groove performance were discussed. The results show that the bottom oil layer is the key for grooves to achieve the lubrication efficiency enhancement, and its distribution can reflect the groove-enhancing performance. The groove width that best adapts to the change of working conditions increases with the increase of oil supply amount and nozzle diameter. To maintain the stability of bottom oil layer, the nozzle diameter should be larger than the groove width. This research is of great significance to the application of grooves in the lubrication efficiency enhancement of high-speed bearing. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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18 pages, 2869 KiB

Open AccessArticle

SACGNet: A Remaining Useful Life Prediction of Bearing with Self-Attention Augmented Convolution GRU Network

by Juan Xu, Shiyu Duan, Weiwei Chen, Dongfeng Wang and Yuqi Fan

Lubricants 2022, 10(2), 21; https://doi.org/10.3390/lubricants10020021 - 3 Feb 2022

Cited by 12 | Viewed by 3709

Abstract

In recent years, the development of deep learning-based remaining useful life (RUL) prediction methods of bearings has flourished because of their high accuracy, easy implementation, and lack of reliance on a priori knowledge. However, there are two challenging issues concerning the prediction accuracy [...] Read more.

In recent years, the development of deep learning-based remaining useful life (RUL) prediction methods of bearings has flourished because of their high accuracy, easy implementation, and lack of reliance on a priori knowledge. However, there are two challenging issues concerning the prediction accuracy of existing methods. The run-to-failure sequential data and its RUL labels are almost inaccessible in real-world scenarios. Meanwhile, the existing models usually capture the general degradation trend of bearings while ignoring the local information, which restricts the model performance. To tackle the aforementioned problems, we propose a novel health indicator derived from the original vibration signals by combining principal components analysis with Euclidean distance metric, which was motivated by the desire to resolve the dependency on RUL labels. Then, we design a novel self-attention augmented convolution GRU network (SACGNet) to predict the RUL. Combining a self-attention mechanism with a convolution framework can both adaptively assign greater weights to more important information and focus on local information. Furthermore, Gated Recurrent Units are used to parse the long-term dependencies in weighted features such that SACGNet can utilize the important weighted features and focus on local features to improve the prognostic accuracy. The experimental results on the PHM 2012 Challenge dataset and the XJTU-SY bearing dataset have demonstrated that our proposed method is superior to the state of the art. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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18 pages, 32381 KiB

Open AccessFeature PaperArticle

A Study on Bearing Dynamic Features under the Condition of Multiball–Cage Collision

by Shuaijun Ma, Xiaohong Zhang, Ke Yan, Yongsheng Zhu and Jun Hong

Lubricants 2022, 10(1), 9; https://doi.org/10.3390/lubricants10010009 - 11 Jan 2022

Cited by 38 | Viewed by 4325

Abstract

Cage stability directly affects the dynamic performance of rolling bearing, which, in turn, affects the operating state of rotating equipment. The random collision between the rolling elements and the cage pocket is the main reason for cage instability. In this paper, from the [...] Read more.

Cage stability directly affects the dynamic performance of rolling bearing, which, in turn, affects the operating state of rotating equipment. The random collision between the rolling elements and the cage pocket is the main reason for cage instability. In this paper, from the perspective of the relative sliding velocity between the rolling elements and the bearing raceway, the interactions of the rolling elements and the cage pockets were analyzed, and the four zones with different collision features were defined. On this basis, and on the basis of the bearing dynamics model, the interaction of two adjacent rolling elements and the cage pockets in the a’–b’ area is discussed, and the peak impact force of the adjacent two balls and the cage pockets was investigated in terms of the rotation speed, radial load, acceleration/deceleration, and materials. When the ball runs close to the loaded zone, the probability of multiball random collision increases, which leads to an increase in the cage instability. At the entrance of the loaded zone, the peak impact force has the greatest impact on the cage stability during the acceleration process. Compared to the radial load applied to the bearing, the peak impact force is more sensitive to the bearing speed changes. The multiball collision analysis method provides a new idea for the research of cage stability. Full article

(This article belongs to the Special Issue Advances in Bearing Lubrication and Thermal Sciences)

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