DOI QR코드

DOI QR Code

Estimation of the Overhaul Cycle Time for KTX Wheelset Bearing by RCF Test

RCF 시험을 통한 KTX 윤축베어링의 분해 정비 주기 평가

  • Sim, Dae-Sop (Dept. of Railway System, Graduate School of Railway, Seoul National University of Science and Technology) ;
  • Heo, Tae-Hyeon (Dept. of Mechanical Engineering, Graduate School, Seoul National University of Science and Technology) ;
  • Park, Young-il (Dept. of Mechanical System Design Engineering, Seoul National University of Science and Technology) ;
  • Kim, Hong Seok (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology) ;
  • Shin, Ki-Hoon (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology) ;
  • Cheong, Seong Kyun (Dept. of Mechanical and Automotive Engineering, Seoul National University of Science and Technology)
  • 심대섭 (서울과학기술대학교 철도전문대학원 철도시스템학과) ;
  • 허태현 (서울과학기술대학교 일반대학원 기계공학과) ;
  • 박영일 (서울과학기술대학교 기계시스템디자인공학과) ;
  • 김홍석 (서울과학기술대학교 기계.자동차공학과) ;
  • 신기훈 (서울과학기술대학교 기계.자동차공학과) ;
  • 정성균 (서울과학기술대학교 기계.자동차공학과)
  • Received : 2016.01.05
  • Accepted : 2016.02.12
  • Published : 2016.02.29

Abstract

KTX wheelset bearings have thus far been maintained in accordance with the maintenance system of French national railway company, SNCF. The overhaul cycle time (OCT) of KTX wheelset bearings is now 1.4 million km in mileage. This value, however, has not been validated in Korea that has much different railway environments with France. In fact, it is impossible to validate OCT of wheelset bearings directly because they are disassembled and cleaned only when some faults are detected. In this paper, the accuracy of the current OCT value was evaluated indirectly by investigating the effect of grease lubricants on the bearing life. Five grease samples (one new and four aged greases) were used in this study. Four aged greases of different conditions were obtained from four wheelset bearings whose mileages were about 0.3, 1.2, 1.3, and 1.8 million km, respectively. Each grease sample was then injected into the RCF (Rolling Contact Fatigue) tester and fatigue lifetime was experimentally estimated. In addition, the wt% of Fe in each grease sample was analysed. The experiment results reveal that the bearing lifetime is inversely proportional to the mileage of grease sample while the wt% of Fe increases with the mileage of grease sample. Based on the experimental results, it can be concluded that the current OCT value is appropriate for the first overhaul of wheelset bearings. However, further validation is required to determine the second and third OCT values.

Keywords

References

  1. TIMKEN, "Taper Roller Bearing Guide Book", pp. 3, 1998.
  2. Quality Control Division at Korail Metropolitan Railroad, "Reliability Analysis of KTX Axle Bearings", pp. 60-61, 2012.
  3. International Organization for Standardization, "Rolling Bearings-Dynamic Load Ratings and Rating Life", ISO 281, 2007.
  4. Y. Choi and C. R. Liu, "Rolloing Contact Fatigue Life of Finish Hard Machined Surfaces: Part 1. Model Development", Wear, Vol. 261, pp. 492-499. 2006. https://doi.org/10.1016/j.wear.2005.12.003
  5. F. Sadeghi, B. Jalalahmadi, T. S. Slack, N. Raje and N. K. Arakere, "A Review of Rolling Contact Fatigue", Journal of Tribology, Vol. 131, pp. 041403, 2009. https://doi.org/10.1115/1.3209132
  6. K. L. Johnson, "Contact mechanics", Cambridge University Press, 1985.
  7. H. R. Hertz, "Ueber die Beruehrung elastischer Koerper (On Contact Between Elastic Bodies)", Gesammelte Werke (Collected Works), Vol. 1, Leipzig, Germany, 1895.
  8. D. A. H. Hanaor, Y. Gan and I. Einav, "Contact Mechanics of Fractal Surfaces by Spline Assisted Discretisation", International Journal of Solids and Structures, Vol. 59, pp.121-131, 2015. https://doi.org/10.1016/j.ijsolstr.2015.01.021
  9. J. E. Shigley and C. R. Mischke, "Mechanical Engineering Design 5th Edition", McGraw-Hill, 1989.
  10. J. P. Hong, "Mechanical Design 6th Edition: Theory and Practice", Kyobobook, 2013.