1999 Fiscal Year Final Research Report Summary
CHARACTERISTICS AND MECHANISM OF THREAD-LOOSENING BY REPETITION OF MINUTE SLIPPAGE OF BEARING SURFACE
| Project/Area Number |
10650140
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
設計工学・機械要素・トライボロジー
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| Research Institution | SHINSHU UNIVERSITY |
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Principal Investigator |
KASEI Shinji FACULTY OF ENG., SHINSHU UNIVERSITY, PROFESSOR, 工学部, 教授 (90016791)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUOKA Hirohito FACULTY OF ENG., SHINSHU UNIVERSITY, ASSISTANT, 工学部, 助手 (40209515)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Thread loosening / Minute slippage / Backward rotation / Impact load / Loosening mechanism / Loosening test / Locking design |
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| Research Abstract |
Thread loosening under repetition of the bearing surface slippage with order of micrometer or sub-micrometer was investigated. The research objects are loosening mechanism and loosening test method, and basic items for locking design are considered.
(1) With assumption that small change of torsion torque of a bolt shard generated by external force is the major factor to generate backward rotation, behavior from action of external force to occurrence of backward rotation is explained.
(2) Experiments are carried out by using the self-made apparatus. It can apply successive impacts to the joint fastened by a test bolt and nut in the one direction perpendicular to the bolt axis. Thread size for the experiments is M10 or M10 × 1.25. From the experimental results, it is clearly known that the rotational loosening can occur easily and progress in this condition, and it is ascertained that the way of thinking about loosening mechanism is roughly applicable to the case.
(3) Experimental results about some kinds of nut sample shows that relative merits between test samples can be evaluated by this method. This method also has possibility to enable more fine evaluation concerning locking performance, for instance discrimination between the non-rotational loosening and the rotational one.
(4) Fundamental items are presented for locking design. They are prevention of slip on a connecting surface between fastened bodies, permanent deformation of a bearing surface and shapes of bolt and nut. As one of the last item, FEM results being presented on pressure distribution on bearing surfaces, perhaps concerned with locking performance, high influence sensitivity given by angle of the bearing surface is shown.
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Research Products
(8 results)
