DOI QR코드

DOI QR Code

선박용 디젤기관의 운동부 볼트 손상사례에 대한 연구

A case study on the bolt failure of the moving parts of a marine diesel engine

  • Kim, Jong-Ho (Division of Marine System Engineering, Korea Maritime and Ocean University) ;
  • Lee, Jae-Hyun (Division of Marine System Engineering, Korea Maritime and Ocean University)
  • 투고 : 2016.08.24
  • 심사 : 2017.01.06
  • 발행 : 2017.01.31

초록

본 연구대상 디젤기관의 연접봉 볼트, 크랭크 핀 베어링 볼트 등의 손상원인을 조사 분석하기 위하여 수행한 현장검사, 파손부에 대한 시험 및 고찰, 참고문헌 및 연구자의 경험 등을 통하여 다음과 같은 결론을 얻었다. 파손된 크랭크 핀 베어링 볼트는 연접봉 볼트보다 늦게 파손된 것으로 추정된다. 파손된 연접봉 볼트는 충격적인 하중에 의해서 취성파괴된 것이 아니고, 비정상적인 반복하중(예를 들어 체결 볼트의 풀림 등)에 의해서 피로파괴가 되었다는 것을 그 파단면의 모습을 통하여 알 수 있다. 파손된 연접봉 볼트용 U 너트는 윤활유(고착방지제)의 부적절한 사용, 각 실린더와 연접봉 별로 구분되어 사용되지 않았던 것 등으로 인하여 표면 상태가 불량하게 되었고, 이것은 연접봉 볼트의 파손사고에 영향을 미쳤을 가능성이 있다고 할 수 있다. 그리고 파손된 국내 제작품인 연접봉 볼트와 크랭크 핀 베어링 볼트의 기계적 성질, 전조공정 등은 해당 볼트의 설계요건에 적합하다고 할 수 있다.

To investigate and analyze the cause of the failure of the connecting rod bolt and the crank pin bearing bolt of the diesel engine of this study, the following results were obtained through site surveying, the investigation of literature referring to similar failures, testing and inspection of the fracture surface, and the experience of the researchers. The fractured crank pin bearing bolt of the diesel engine is estimated to be damaged later than the connecting rod bolt. From the shape of fracture surface, it is evident that the failed connecting rod bolt is fractured by fatigue failure due to abnormally repeated loads (e.g. loosening of the connecting bolt, etc.), and is not failed by brittle fractures due to the impact load. The surface of the U-nut on the fractured connecting rod bolt has been worsening due to the improper use of lubricant (agent for prevention of thread fixing) and no usage of separating the each connecting rod on each cylinder. Moreover, there is the possibility that those poor surface conditions of the fractured connecting rod bolt have affected the failure of the connecting rod bolt of the main engine. And it could be assumed that the mechanical characteristic and manufacturing process of the failed connecting rod bolt and crank pin bearing bolt, which were made by a domestic company, conform to the design requirements for those bolts.

키워드

참고문헌

  1. C. Scholey and R. R. Lintell-Smith, A Review of Crack and Fracture Mechanisms, Paper No. 3 Session Lloyd's Register of Shipping, United Kingdom, 1976.
  2. M. Fonte and M. de Freitas, Marine main engine crankshaft failure analysis: A case study, Engineering Failure Analysis, vol. 16, no. 6, pp. 1940-1947, 2009. https://doi.org/10.1016/j.engfailanal.2008.10.013
  3. J. H. Kim, "A study on failure cause of a Ssade type rudder stock," Proceedings of the 39th Korean Society of Marine Engineering Spring Conference, p. 27, 2015 (in Korean).
  4. J. H. Kim and J. H. Lee, "A study on failure cause of cam shaft of diesel engine," Proceedings of the 38th Korean Society of Marine Engineering Fall Conference, p. 217, 2014 (in Korean).
  5. M. K. Kang, J. H. Lee, and J. H. Kim, "A study on crank arm deflection and fatigue strength," Proceedings of the 38th Korean Society of Marine Engineering Spring Conference, p. 274, 2014 (in Korean).
  6. J. H. Kim, "A case study on the failure of exhaust valves for marine diesel generator engine," 8th International Symposium on Marine Engineering (ISME 2009), p. 79, 2009.
  7. H. Tsugi, Failure Analysis and Safety Measures ( For Nippon Kaiji Kyokai Registered Ships during 50 Years), Tokyo, Japan: Seizando-Shoten Publishing Company, 1999 (in Japanese).
  8. NYK Line Safety & Environmental Management Group, Cases Studies(Ships Engine Trouble), Tokyo, Japan: Seizando-Shoten Publishing Company, 2008 (in Japanese).
  9. R. C. Juvinall and K. M. Marshek, Fundamentals of Machine Component Design, New York, USA: John Wiley & Sons Inc., 2000.

피인용 문헌

  1. 워터제트 추진기 임펠러 체결용 볼트파손 원인 분석 연구 vol.18, pp.10, 2017, https://doi.org/10.14775/ksmpe.2019.18.10.048