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Li Y.,Taiyuan University of Science and Technology | Ju L.,Taiyuan University of Science and Technology | Qi H.,Taiyuan University of Science and Technology | Zhang F.,Taiyuan University of Science and Technology | And 2 more authors.
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2014

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named "casting-rolling compound forming technology" is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency. © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2014.


Li Y.,Taiyuan University of Science and Technology | Qi H.,Taiyuan University of Science and Technology | Li Q.,Taiyuan University of Science and Technology | Chen G.,Luoyang LYC Bearing Co. | And 2 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013

Aiming at many disadvantages such as long process, more heating times and wasting materials and energy in technology of manufacturing ring parts currently in use, a new cast-rolling forming technology of ring parts is put forward and researched. A cast ring blank is directly rolled into ring part in this new technology, so it possess many advantages such as saving energy, saving materials and shorten the process. In this new technology, the cast quality, organization and performance of cast blank has important influence to rolling process and the quality of ring part. Take 42CrMo commonly used in bearing ring for example, the smelt and casting process for producing high-quality ring casts is researched by means of theoretical analysis and simulation. The industrial test on blank cast of bearing rings is completed in Luoyang LYC Co. ltd. It is shown from the results of experiments and tests that the ring blank produced by this cast process possess favorable quality, microstructure and mechanical character and can provide high quality cast blanks for new cast-rolling forming technology. © 2013 Journal of Mechanical Engineering.


Wu Y.Z.,University of Sichuan | Wang Q.Y.,University of Sichuan | Ouyang Q.L.,Luoyang LYC Bearing Co.
Applied Mechanics and Materials | Year: 2012

Using the ultrasonic fatigue test method, the influence of subjection to plasma nitriding surface modifications on the ultra-high cycle fatigue behavior of Ti-6Al-4V was investigated, then a comparison with corresponding behaviors of the normal Ti-6Al-4V was made. The results show the S-N curve of Ti-6Al-4V with plasma nitriding surface modifications still continuously declines, no conventional fatigue limit exists for Ti-6Al-4V. Plasma nitriding surface modifications enhance surface hardness, but they make the material fatigue strength decrease by about 17 %. The fractography of fatigue failure has been observed by scanning electron microscopy. The observation shows that fatigue failure initiates from internal of specimen after the fatigue life of 10 8 cycles and fatigue cracks mainly initiate from the surface of specimen before the fatigue life of 10 8 cycles. © (2012) Trans Tech Publications.


Song H.,Luoyang LYC Bearing Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2016

Effect of subzero treatment and cryogenic treatment on carbide morphology, Rockwell hardness, hardness gradient and the depth of the G20Cr2Ni4A steel carburized layer was investigated by means of SEM, hardness tester and micro-hardness tester. The results indicate that subzero treatment and cryogenic treatment can increase dispersed precipitation of the carbides, reduce retained austenite, thus the hardness of the carburized layer increases, while the effect of subzero treatment on depth may be very small. © 2016, Editorial Office of "Jinshu Rechuli". All right reserved.


Wang H.,Nanjing University of Technology | Wang H.,Luoyang LYC Bearing Co. | Hong R.,Nanjing University of Technology | Chen J.,Nanjing University of Technology | Tang M.,Nanjing University of Technology
International Journal of Engineering, Transactions A: Basics | Year: 2015

Slewing bearing, which is widely applied in tank, excavator and wind turbine, is a critical component of rotational machines. Standard procedure for bearing life calculation and condition assessment has been established for general rolling bearings. Nevertheless, relatively less literatures in regard to the health condition assessment of slewing bearing has been published in past. Real time health condition assessment for slewing bearing is used for avoiding catastrophic failures by detectable and preventative measurement. In this paper, a new strategy is presented for health evaluation of slewing bearing based on multiple characteristic parameters, and ANN (Artificial Neural Network ) and ANFIS(Adaptive Neuro-Fuzzy Inference System ) models are demonstrated to predict the health condition of slewing bearings. The prediction capabilities offered by ANN and ANFIS are shown by data obtained from full life test of slewing bearings in NJUT test System. Various statistical performance indexes have been utilized to compare the performance of two predicted models. The results suggest that ANFIS-based prediction model outperforms ANN models.


Xia X.,Henan University of Science and Technology | Fan J.,Henan University of Science and Technology | Chen L.,Henan University of Science and Technology | Liu J.,Luoyang LYC Bearing Ltd Company | Wang J.,Luoyang LYC Bearing Ltd Company
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2012

Based on the information poor theory, the relationship between the starting friction torque of the slewing bearing and the load was discussed to reveal nonlinear evolution characteristics of the estimated true value, fluctuation range, information entropy, variation coefficient, and probability density function of the starting friction torque. In the simulated experiment, two different slewing bearings were adopted, the load was changed five times for each bearing, the starting friction torques of six points which were evenly distribution on the surface of the inner ring were measured simultaneously, and variation analysis of the test data was made. The test result showed that with the rise of the load, the estimated true value nonlinearly increased and the variation coefficient nonlinearly decreased in view of the overall situations, at which there was a sensitive spot where the variation coefficient increased abnormally. This indicated that the starting friction torque of the slewing bearing had the uncertainty of the variable and the polytropy of the function. The findings provide a reference for analyzing the measuring system and improving the bearing performance.


Liu Y.-J.,Sichuan University | Ouyang Q.-L.,Luoyang LYC Bearing Co. | Tian R.-H.,Sichuan University | Wang Q.-Y.,Sichuan University
Yiyong Shengwu Lixue/Journal of Medical Biomechanics | Year: 2011

Objective: To study the ultra-high cycle fatigue behaviors of the Ti-6Al-4V alloy implant after subjection to simulated body fluid (SBF) environment exceeding 107 cycles, and to predict its service life. Method: The Ti-6Al-4V alloy specimens were subjected to SBF in two groups for two days and six days respectively; using the ultrasonic fatigue testing technique, the ultra-high cycle fatigue properties of Ti-6Al-4V alloy after subjection to SBF in body temperature were studied and the initiation mechanisms of fatigue cracks were investigated and analyzed with scanning electron microscopy (SEM) and energy dispersive atomic X-ray (EDA X-ray). Then, a comparison with corresponding behaviors of the normal Ti-6Al-4V alloy was made. Results: The S-N curve of the Ti-6Al-4V alloy after subjection had the similar tendency as that of the normal one, showing that they descended continuously during 104 and 108 cycles and the descending tendency was lower in the region of 107~108 cycles; the life of the specimens after subjection dropped before the fatigue life of 107 cycles and was smaller after the fatigue life of 107 cycles than that of the normal ones; the life of the specimens subjected for six days had little difference with that subjected for two days; fracture could still occur beyond 107 cycles, showing that there was no fatigue limit as the traditional fatigue conception described. Fatigue cracks mainly initiated from the surface of specimen before the fatigue life of 107 cycles and some specimens had multiple crack initiation sites; fatigue failure initiated from internal inclusion where mostly the element Al aggregated after the fatigue life of 108 cycles. Conclusions: The ultra-high cycle fatigue properties of the Ti-6Al-4V alloy decreas a little with SBF subjection; the initiation site of the fatigue crack changes from the surface to the internal defect with the increase of the number of cycle.


Li Y.,Taiyuan University of Science and Technology | Qi H.,Taiyuan University of Science and Technology | Fu J.,Taiyuan University of Science and Technology | Chen G.,Luoyang LYC Bearing Co. | And 2 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2014

As compared with commonly used manufacturing process, the new cast-rolling forming technology of ring parts has many advantages such as saving energy and material and shortening production process. Taking 42CrMo steel commonly used in bearing ring for example, the rolling forming mechanism and process of bearing rings based on cast blanks is investigated. Microstructure evolution mechanism and laws of 42CrMo during deformation is revealed by means of thermal simulation experiments and microstructure analysis. Forming process parameters and their influence on metal deformation and microstructure evolution during rolling forming of cast ring are researched by theoretical analysis and numerical simulation. The integration regulation of shaping and performance in cast-rolling process of ring part is achieved. The industrial test on cast-rolling forming of bearing rings is completed in Luoyang LYC Co., Ltd. It is shown from the results of experiments and performance tests that the ring parts produced by this new technology possess favorable mechanical character and meet the requirement of industrial use. © 2014 Journal of Mechanical Engineering.


Xia X.,Henan University of Science and Technology | Liu J.,Luoyang LYC Bearing Ltd Company | Chen L.,Henan University of Science and Technology
Advanced Materials Research | Year: 2011

By simulation experiments, the relation between the starting friction torque of a blade bearing and the overturning moment is explored in order to disclose the nonlinear evolution characteristics of the sample mean and variation coefficient of the starting friction torque. Via the variation analysis of the test data, the result indicates that with the rise of the overturning moment, the sample mean is nonlinearly increased and the sample variation coefficient is nonlinearly decreased in view of the overall situation, at which there is a sensitive spot where the sample variation coefficient makes larger abnormally. This is a new discovery. Perhaps it can lay the foundation for analyzing the starting friction torque measurement system and for designing the blade bearing system. © 2011 Trans Tech Publications, Switzerland.


Dong H.,Luoyang LYC Bearing Co. | Shen W.,Luoyang LYC Bearing Co. | Wang M.,Luoyang LYC Bearing Co. | Yuan X.,Luoyang LYC Bearing Co.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2015

The chemical composition and microstructure of the main bearing's roller used for import shield machine were analyzed, and heat treatment processes of the roller at different isothermal temperature and different isothermal time were tested and analysed. The results show that the optimum process is heating at 885 ℃ for 3 h and isothermal at 220 ℃ for 5 h. The chemical composition and microstructure of the roller are correspond to the technical level of import main bearing's roller. ©, 2015, Chinese Mechanical Engineering Society of Heat Treatment. All right reserved.

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