Theoretical research on sector oil-pads’ mechanical property in hydrostatic thrust bearing based on constant flow

2017 ◽  
Vol 69 (4) ◽  
pp. 491-506 ◽  
Author(s):  
Xibing Li ◽  
Tian Cheng ◽  
Ming Li ◽  
Mingjian Li ◽  
Ruren Wu ◽  
...  
Keyword(s):  
Pressure Difference ◽  
Thrust Bearing ◽  
Rapid Development ◽  
Numerical Control ◽  
Theoretical Research ◽  
Mechanical Equipment ◽  
Content Type ◽  
Large Size ◽  
Lubrication Performance ◽  
Oil Flow

Purpose The purpose of this study with the rapid development of the heavy/large mechanical equipment, the heavy computer numerical control (CNC) vertical lathe has become the ideal processing equipment for the parts of those mechanical equipments. The main factor which affects the machining quality and efficiency of heavy CNC vertical lathe is the mechanical properties of the hydrostatic thrust bearing. Design/methodology/approach This paper did the research based on the large size sector oil pad’s lubrication performance of the hydrostatic thrust bearing in the heavy/large equipments, establishing the lubrication performance distribution mathematical model of the velocity field, flow field, pressure field and so on, analyzing the bearing behavior of the large size sector oil pad. Findings The results show that the oil flow generated by the plate relative motion will be greater than that generated by the pressure difference in area B, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. The oil flow generated by the centrifugal force will be greater than that generated by the pressure difference in area C, with the rotational speed’s increasing of the hydrostatic thrust bearing, and the direction is opposite. When the rotational speed of the hydrostatic thrust bearing is too high, the friction heat will be not easy to be sent out. The bearing rotating speed should be lower than the comparatively smaller one of ω1 and ω2, which can help avoid the rise of too high temperature. Originality/value The research provides powerful theoretical foundation for practical application of the large size sector oil pad hydrostatic thrust bearing, its structure design and operating reliability, realizing the lubrication performance prediction of the large size hydrostatic thrust bearing.

Theoretical research on mechanical property of rectangular oil pad in hydrostatic thrust bearing based on constant flow

2016 ◽  
Vol 68 (3) ◽  
pp. 392-403 ◽  
Author(s):  
Xibing Li ◽  
Tian Cheng ◽  
Ming Li ◽  
Mingjian Li ◽  
Ruren Wu ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Structure Design ◽  
Numerical Control ◽  
Theoretical Research ◽  
Content Type ◽  
Rotating Speed ◽  
Large Size ◽  
Lubrication Performance ◽  
Oil Flow ◽  
Bearing Behavior

Purpose This paper aims to research the lubrication performance of large-size rectangular oil pad in hydrostatic thrust bearing for heavy computer numerical control (CNC) vertical lathe. Design/methodology/approach The research establishes the mathematical models of velocity, flux and pressure fields, etc., for lubrication performance distribution, and analyzes its load-bearing behavior. Findings When hydrostatic thrust bearing’s rotating speed is within ω1-ω2, the oil flow generated by plate’s relative motion is greater than that generated by pressure difference and centrifugal force, and in the opposite direction, making it not easy to emit friction heat, so the rotating speed range ω1-ω2 should be avoided for bearing. Originality/value The research provides powerful theoretical basis for the structure design, operating reliability and practical application of large size rectangular oil pad hydrostatic thrust bearing, and realizing the prediction of its lubrication performance.

Effect of recess depth on lubrication performance of annular recess hydrostatic thrust bearing by constant rate flow

2018 ◽  
Vol 70 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Jun-peng Shao ◽  
Guang-dong Liu ◽  
Xiao-dong Yu ◽  
Yan-qin Zhang ◽  
Xiu-li Meng ◽  
...  
Keyword(s):  
Thrust Bearing ◽  
Simulation Method ◽  
Content Type ◽  
Oil Film ◽  
Constant Rate ◽  
Lubrication Performance ◽  
Optimal Value ◽  
Improved Performance ◽  
Lubrication Characteristics ◽  
Volume Method

Purpose The purpose of this paper is to describe a simulation and experimental research concerning the effect of recess depth on the lubrication performance of a hydrostatic thrust bearing by constant rate flow. Design/methodology/approach The computational fluid dynamics and finite volume method have been used to compute the lubrication characteristics of an annular recess hydrostatic thrust bearing with different recess depths. The performances are oil recess pressure, oil recess temperature and oil film velocity. The recess depth has been optimized. A test rig is established for testing the pressure field of the structure of hydrostatic thrust bearing after recess depth optimization, and experimental results show that experimental data are basically identical with the simulation results, which demonstrates the validity of the proposed numerical simulation method. Findings The results demonstrate that the oil film temperature decreases and the oil film pressure first increases and then decreases with an increase in the recess depth, but oil film velocity is constant. To sum up comprehensive lubrication performance, the recess depth of 3.5 mm is its optimal value for the annular recess hydrostatic thrust bearing. Originality/value The computed results indicate that to get an improved performance from a constant flow hydrostatic thrust bearing, a proper selection of the recess depth is essential.

Influence of recess shape on comprehensive lubrication performance of high speed and heavy load hydrostatic thrust bearing

2019 ◽  
Vol 71 (2) ◽  
pp. 301-308
Author(s):  
Mubing Yu ◽  
Xiaodong Yu ◽  
Xuhang Zheng ◽  
Hang Qu ◽  
Tengfei Yuan ◽  
...  
Keyword(s):  
High Speed ◽  
Thrust Bearing ◽  
Great Influence ◽  
Constant Flow ◽  
Heavy Load ◽  
Content Type ◽  
Lubrication Performance ◽  
Improved Performance ◽  
Volume Method ◽  
Selection Of

Purpose This paper aims to describe a theoretical and experimental research concerning influence of recess shape on comprehensive lubrication performance of high speed and heavy load hydrostatic thrust bearing with a constant flow. Design/methodology/approach The lubrication performance of a hydrostatic thrust bearing with different recess shape under the working conditions of high speed and heavy load has been simulated by using computational fluid dynamics and finite volume method. Findings It is found that the comprehensive lubrication performance of a hydrostatic thrust bearing with circular recess is optimal. The results demonstrate that recess shape has a great influence on the lubrication performance of the hydrostatic thrust bearing. Originality/value The simulation results indicate that to get an improved performance from a hydrostatic thrust bearing with constant flow, a proper selection of the recess shape is essential.

Study on Mechanical Properties of Lost Foam Pattern in Machining

2021 ◽  
Vol 904 ◽  
pp. 148-153
Author(s):  
Hong Qi Luo ◽  
Xia Liu ◽  
Po Wang
Keyword(s):  
Mechanical Properties ◽  
Manufacturing Industry ◽  
Rapid Development ◽  
Numerical Control ◽  
Processing Technology ◽  
Lost Foam Casting ◽  
Mechanical Equipment ◽  
Theoretical Support ◽  
Foam Pattern ◽  
Lost Foam

Lost foam casting has special requirements on the process performance of molding machinery, and the processing technology of Lost foam casting pattern is one of the core and key technologies of Lost foam casting. The research status of lost foam pattern and the safety problems existing in the process of lost foam casting were analyzed. The mechanical properties of lost foam pattern and its mechanical property model were studied, which provided theoretical support for the research of numerical control processing and safe casting of lost foam pattern. The development of Lost foam casting pattern NC processing technology is conducive to the use of information technology, digital technology to enhance the technological progress of traditional industries, promote the clean production of Lost foam casting, realize energy saving and emission reduction, and promote the rapid development of mechanical equipment manufacturing industry.

Experimental and numerical analysis of a self-circulating oil bearing system for gear pumps

2018 ◽  
Vol 70 (1) ◽  
pp. 115-125 ◽  
Author(s):  
Mo Jintao ◽  
Gu Chaohua ◽  
Pan Xiaohong ◽  
Zheng Shuiying ◽  
Ying Guangyao
Keyword(s):  
Flow Rate ◽  
Pressure Difference ◽  
The Self ◽  
Gear Pump ◽  
Moderate Pressure ◽  
Test Rig ◽  
Content Type ◽  
Oil Flow ◽  
Gear Pumps ◽  
Bearing System

Purpose For moderate pressure and high pressure gear pumps, the temperature failure problem of bearings is now of considerable concern because of their heavy loads. However, the compact structure and the efficiency consideration make it extremely difficult to improve the bearing cooling. A self-circulating oil bearing system is developed for gear pumps with self-lubricating bearings to solve this problem. The oil is aspirated in from the low pressure chamber of the gear pump and discharged to the same chamber by using the pressure difference in the journal bearing, thus achieving the self-circulation. Design/methodology/approach An experiment test rig has been built for the feasibility study. The oil flow rate under different speeds has been recorded. Furthermore, the temperatures of the bearings with or without the oil circulation have been compared. Additionally, the oil flow in the test rig has been simulated using computational fluid dynamics codes. Findings The experimental and numerical results agree well. The experimental results indicate that the oil flow rate increases approximately linearly with the speed and the bearing temperature can be lowered successfully. The calculation results indicate that the bearing load capacity is nearly the same. Both the experimental and numerical studies establish that the self-circulating oil bearing system works successfully. Originality value As far as the authors know, it is the first time to find that the self-circulation can be built using the pressure difference in the bearing oil film, and this principle can be applied in the cooling and lubrication of the gear pumps to solve the temperature failure problem.

Analysis of tilting-pad thrust bearing static instability and lubrication performance under the bistability

2014 ◽  
Vol 66 (5) ◽  
pp. 584-592 ◽  
Author(s):  
Ouyang Wu ◽  
Yuan Xiaoyang ◽  
Jia Qian
Keyword(s):  
Working Conditions ◽  
Thrust Bearing ◽  
Equilibrium Points ◽  
Static Equilibrium ◽  
Distribution Area ◽  
Acceptance Test ◽  
Content Type ◽  
Lubrication Performance ◽  
Tilting Pad ◽  
Static Instability

Purpose – The purpose of this paper is to analyze the problems of tilting-pad thrust bearing static instability and lubrication performance under static bistability. Design/methodology/approach – The static equilibrium state of tilting-pad thrust bearing is analyzed, and key parameters are extracted from the general lubrication model. Then, a distribution area of bearing static equilibrium points is achieved by solving the model. The area is divided into three sub-areas which represent monostabillity, bistability and instability, and an unstable boundary of the area is discovered. By these findings, a reversible lubrication failure phenomenon is explained. A calculation method is proposed to obtain bearing lubrication performance under the bistability. Findings – The variation of working conditions can lead to migration of unstable boundary and static instability. After resuming the working conditions, unstable boundary will resume in situ, and the bearing will operate steadily again. Moreover, there is a big difference between the two groups of lubrication performance solutions under the bistability. Practical implications – The static stability acceptance test of tilting-pad thrust bearing should be implemented under start–stop, accidental excitation and other conditions before service to prevent such lubrication failure phenomenon. Moreover, fulcrum position of the bearing pad should be kept away from the bistable area. Originality/value – This paper has preliminarily revealed a static instability mechanism of tilting-pad thrust bearing, analyzed bistability lubrication performance and proposed some suggestions to improve the bearing stability.

Study on Software Reliability of Numerical Control System

2013 ◽  
Vol 278-280 ◽  
pp. 2085-2089
Author(s):  
Chong Peng ◽  
Yu Jie Meng ◽  
Li Yun Lan
Keyword(s):  
Software Reliability ◽  
Rapid Development ◽  
Numerical Control ◽  
Theoretical Research ◽  
Engineering Practice ◽  
Cnc System ◽  
Servo Drive ◽  
Failure Data ◽  
Hardware Reliability ◽  
Servo Drive System

With the rapid development of electronic components manufacturing technology and the application of reliability technology, the hardware reliability of the CNC system and servo drive system has been greatly improved. Currently, the performance and functionality of CNC system, which achieved gradually by the software instead of hardware, is becoming increasingly complex. However, very few researches on the reliability of CNC system software was presented. In this paper, the basic conceptions and important of CNC software reliability were discussed, and comparative analysis on the research status at domestic and abroad were studied from the view of theoretical research and engineering practice. Meanwhile, the paper collected field failure data on 30 CNC systems in six months, and reliability analysis was made based on the data.

Load carrying capacity of a novel magnetic-liquid double suspension fixed pad thrust bearing

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shengtong Wang ◽  
Ouyang Wu ◽  
Zhe Li ◽  
Bin Wang
Keyword(s):  
Peer Review ◽  
Magnetic Force ◽  
Thrust Bearing ◽  
Hydrodynamic Pressure ◽  
Magnetic Liquid ◽  
Content Type ◽  
High Speeds ◽  
Halbach Array ◽  
Lubrication Performance ◽  
New Type

Purpose Proposing a new type of water-lubricated thrust bearing meets the load-bearing requirements of high-power shaft-less rim driven thrusters. Design/methodology/approach The designs were tested by establishing a bearing thermal-fluid-magnetic comprehensive simulation model and developing bearing fluid film force and magnetic simulation. Lubrication performance tests were carried out on the bearing test rig. Findings The Halbach array of magnet blocks is able to reach the maximum magnetic force. The material of sheath can help increase the magnetism. The magnetism is able to reduce wear during low-speed and the start-stop phase, while the eddy current loss at high speeds will lead to a decrease in magnetic force. The experiment found that the bearing was more stable at low speeds and would not demagnetize due to the temperature rise, but it is necessary to pay attention to the running stability at high speeds to prevent rubbing and impact. Originality/value An innovative combination of hydrodynamic pressure and permanent magnetic repulsion was observed to form a magnetic-liquid double suspension bearing with large bearing capacity. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0295

Achieving productive reliability through applying statistical distribution functions

2019 ◽  
Vol 37 (8) ◽  
pp. 1125-1149
Author(s):  
Mahdi Karbasian ◽  
Ramin Rostamkhani
Keyword(s):  
Failure Time ◽  
Distribution Functions ◽  
Statistical Distribution ◽  
Numerical Control ◽  
Theoretical Research ◽  
Content Type ◽  
Equipment Reliability ◽  
Efficiency And Effectiveness ◽  
Statistical Distribution Function ◽  
Efficient Option

Purpose The purpose of this paper is to find the proper statistical distribution function, which can cover the failure time of a single machine or a group of machines. To this end, an innovative program is written in an Excel software, capable of assessing at least six statistical distribution functions. This research study intends to show the advantages of applying statistical distribution functions in an integrated model format to create or increase productive reliability machines. Productive reliability is a simultaneous combination of efficiency and effectiveness in reliability. Design/methodology/approach The method of theoretical research methodology comprises data collection tools, reference books and articles in addition to exploiting written reports of the Iranian Center for Defence’s Standards. The practical research method includes deploying and assessing the proposed model for a selected machine (in this case a computerized numerical control machine). Findings A comprehensive program in an Excel software having the capability of assessing at least six statistical distribution functions was developed to find the most efficient option for covering the failure times of each machine in the shortest time with the highest precision. This is regarded as the most important achievement of the present study. Furthermore, the advantages of applying the developed model are discussed and a large group of which have direct influences on the productivity of equipment reliability. Originality/value The originality of the research was ascertained by managers and experts working in maintenance issues at the different levels of the Defense Industries Organization.

Recent Patents on the Angular Contact Ball Bearing of High-Speed Motorized Spindle

2020 ◽  
Vol 13 ◽  
Author(s):  
Yudong Bao ◽  
Linkai Wu ◽  
Yanling Zhao ◽  
Chengyi Pan
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Rapid Development ◽  
Ceramic Materials ◽  
Development Trend ◽  
Numerical Control ◽  
Angular Contact Ball Bearing ◽  
Practical Applications ◽  
High Speed Cutting ◽  
Advantages And Disadvantages

Background:: Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers, The performance of the bearing directly affects the machining efficiency of the machine tool, Obtaining a higher value is the direction of its research and development. Objective:: By analyzing the research achievements and patents of electric spindle angular contact bearings, summarizing the development trend provides a reference for the development of electric spindle bearings. Methods:: Through the analysis of the relevant technology of the electric spindle angular contact ball bearing, the advantages and disadvantages of the angular contact ball bearing are introduced, and the research results are combined with the patent analysis. Results:: With the rapid development of high-speed cutting and numerical control technology and the needs of practical applications, the spindle requires higher and higher speeds for bearings. In order to meet the requirements of use, it is necessary to improve the bearing performance by optimizing the structure size and improving the lubrication conditions. Meanwhile, reasonable processing and assembly methods will also have a beneficial effect on bearing performance. Conclusion:: With the continuous deepening of bearing technology research and the use of new structures and ceramic materials has made the bearing's limit speed repeatedly reach new highs. The future development trend of high-speed bearings for electric spindles is environmental protection, intelligence, high speed, high precision and long life.

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