New Class of High-Speed Steels for Aero Rolling Bearings

2017 ◽  
pp. 260-274 ◽  
Author(s):  
Bryan D. Allison ◽  
Jean-Baptiste Coudert ◽  
Gaël Guétard ◽  
Alexandre Mondelin ◽  
Renaud Vermoere ◽  
...  
Keyword(s):  
High Speed ◽  
Rolling Bearings ◽  
New Class

Oil Pumping in High Speed and High Loaded Ball Bearings

2004 ◽  
Author(s):  
Michael Flouros
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Research Programme ◽  
Aircraft Engine ◽  
Ball Bearings ◽  
European Research ◽  
Rolling Bearings ◽  
Engine Design ◽  
Oil Flow ◽  
Total Oil

Trends in aircraft engine design cause increased mechanical stress requirements for rolling bearings. Consequently high amounts of heat are rejected which results in high oil scavenge temperatures. The direction of oil flow in the bearing can considerably affect the heat transported by the oil. An RB199 turbofan bearing and its associated chamber were modified to carry out the survey. The test bearing was a 124mm PCD ball bearing. The bearing has a split inner-ring employing under-race lubrication by two individual jets. The total oil flow could be devided to any ratio through the jets. This had an impact on the oil scavenge temperatures and the scavenge flows on both sides of the bearing. Significant reduction in the ‘heat to oil’ was achieved when oil was fed at certain proportions (ratio). This work is part of the European Research programme Brite Euram ATOS (Advanced Transmission and Oil Systems).

scholarly journals A new model for predicting the mechanical efficiency of ball screws based on the empirical equations for the friction torque of rolling bearings

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401880017 ◽  
Author(s):  
Chang-Guang Zhou ◽  
Hu-Tian Feng ◽  
Yi Ou
Keyword(s):  
Rotational Speed ◽  
Axial Load ◽  
High Speed ◽  
Mechanical Efficiency ◽  
Friction Torque ◽  
Numerical Control ◽  
Measuring System ◽  
Empirical Equations ◽  
Rolling Bearings ◽  
New Model

Based on the empirical equations for the friction torque of rolling bearings, this article proposes a new model for predicting the friction torque and mechanical efficiency of ball screws. Meanwhile, a novel measuring system is constructed to obtain the mechanical efficiency of ball screws, where both the axial load and rotational speed are stable and adjustable. The experimental results at a rotational speed of 1000 r/min agree well with the theoretical values calculated by the present method, which show that the mechanical efficiency of ball screws increases with increasing axial load. Moreover, the model built in this article is more applicable to a relatively high-speed condition. The new model can be easily used to obtain the friction torque and mechanical efficiency for ball screws, which is essential for improving the performance of ball screws and the computer numerical control machine tools.

scholarly journals Ultrafast optical imaging technology: principles and applications of emerging methods

Nanophotonics ◽  
2016 ◽  
Vol 5 (4) ◽  
pp. 497-509 ◽  
Author(s):  
Hideharu Mikami ◽  
Liang Gao ◽  
Keisuke Goda
Keyword(s):  
Optical Imaging ◽  
High Speed ◽  
Image Sensors ◽  
Frame Rate ◽  
High Temporal Resolution ◽  
New Class ◽  
Advantages And Disadvantages ◽  
Ultrafast Optical ◽  
Small Field Of View ◽  
Shutter Speed

AbstractHigh-speed optical imaging is an indispensable technology for blur-free observation of fast transient dynamics in virtually all areas including science, industry, defense, energy, and medicine. High temporal resolution is particularly important for microscopy as even a slow event appears to occur “fast” in a small field of view. Unfortunately, the shutter speed and frame rate of conventional cameras based on electronic image sensors are significantly constrained by their electrical operation and limited storage. Over the recent years, several unique and unconventional approaches to high-speed optical imaging have been reported to circumvent these technical challenges and achieve a frame rate and shutter speed far beyond what can be reached with the conventional image sensors. In this article, we review the concepts and principles of such ultrafast optical imaging methods, compare their advantages and disadvantages, and discuss an entirely new class of applications that are possible using them.

Dynamic loads and cage wear in high-speed rolling bearings

Wear ◽  
1991 ◽  
Vol 147 (1) ◽  
pp. 119-134 ◽  
Author(s):  
Pradeep K. Gupta
Keyword(s):  
High Speed ◽  
Dynamic Loads ◽  
Rolling Bearings

Development of Test Rig for High-Speed Railway Rolling Bearings

2011 ◽  
Vol 101-102 ◽  
pp. 702-707 ◽  
Author(s):  
Zhao Dong Huang ◽  
Bo Qian Fan ◽  
Xiao Ping Ouyang ◽  
Ling Ling Xu ◽  
Zhi Gang Wang
Keyword(s):  
High Speed ◽  
High Performance ◽  
Rolling Bearing ◽  
Main Shaft ◽  
Heavy Vehicles ◽  
Test Rig ◽  
Rolling Bearings ◽  
Heavy Load ◽  
High Speed Railway ◽  
Mechanical Structure

The rolling bearing test rig for heavy vehicles often works under heavy load and high speed, thus it requires high performance for the main shaft and mechanical structure. In this paper a design of test rig for high-speed railway rolling bearings is presented, in which a new structure is adopted to reduce the load on the support bearings. The basic idea is to position the load in a way that they can be balanced by each other.

scholarly journals Study on the Thermal Distribution Characteristics of High-Speed and Light-Load Rolling Bearing Considering Skidding

2018 ◽  
Vol 8 (9) ◽  
pp. 1593 ◽  
Author(s):  
Junning Li ◽  
Jiafan Xue ◽  
Zhitao Ma
Keyword(s):  
Temperature Distribution ◽  
Power Loss ◽  
High Speed ◽  
Roller Bearing ◽  
Transient Temperature ◽  
Rolling Bearings ◽  
Slip Ratio ◽  
Friction Power ◽  
Thermal Distribution ◽  
Light Load

Skidding, which frequently occurs in high-speed rolling bearings, has a significant effect on the thermal distribution and service reliability of the bearings. An improved theoretical model of friction power loss distribution in high-speed and light-load rolling bearings (HSLLRBs) considering skidding is established, and the effects of various operating parameters on the friction power loss are investigated. The results show that the friction power loss of the inner ring and outer ring as well as the total friction power loss of the bearing increase as the slip ratio increases, but that the friction power loss of the cage guide surface and roller oil churning show a reverse trend. In addition, the increase in inner ring speed and kinematic viscosity leads to an increase in bearing friction power loss. The steady and transient temperature field distribution of HSLLRBs is obtained by the finite element method (FEM), and the results show that the inner ring raceway has the highest temperature, whereas the cage has the lowest. The temperature distribution test rig of a full-size roller bearing is constructed, and the influence mechanism of the slip ratio, rotation speed, load, lubrication, and surface topography on the bearing temperature distribution are obtained. The experimental results are consistent with the theoretical results, which also validates the theoretical method.

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