著者

橋村 真治 小松 恭一 大津 健史 関戸 裕二郎

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.62, no.3, pp.205-216, 2017-03-15 (Released:2017-03-16)

参考文献数

12

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In recent years, self-loosening detail mechanisms of bolted joints had been revealed using three dimensional FE analysis in which the bolts and the nuts have almost perfect configurations geometrically. However the configurations of actual bolts and nuts have certainly errors. Wear on contact surfaces also occurs in the actual bolted joint. Hence it is not easy to accurately simulate the actual bolted joint by only FEM. In this study, an influence of lubricants on self-loosening characteristics have been investigated in order to understand actual phenomena in self-loosening process. The self-loosening tests for a hexagon head cap screw M10 due to transverse vibration were performed under lubricated conditions by Machine oil ISO VG46, Molybdenum disulfide grease and Polyisobuthylene which is used as a special lubricant for bolt tightening. A bearing surface configuration of the bolt was controlled in this study. The results showed that the bolted joints lubricated by Polyisobuthylene had a higher resistance for self-loosening than the bolted joints lubricated by Molybdenum disulfide grease and Machine oil ISO VG46. The number of cycle until loosening depended on bearing surface configurations.

著者

橋村 真治 山田 直樹 戸田 均

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集A編 (ISSN:18848338)

巻号頁・発行日

vol.78, no.791, pp.1013-1022, 2012 (Released:2012-07-25)

参考文献数

10

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In this study, influence of nut configuration on fatigue characteristic of bolt/nut assembly under transverse vibration has been investigated. In the experiments, the apparent fatigue limits were investigated for two bolt/nut assemblies tightened with a flange nut and a tapered nut. The results showed that the apparent fatigue limit of the bolt/nut assembly tightened with the tapered nut was higher than that of the flange nut. Its causes were revealed by FE Analyses. As the result, it could be seen that a difference of nut inclinations when the assembly received the transverse load caused the difference of fatigue limits. It was also seen that the nominal stresses at root of the first thread were different even if the same transverse load was applied to the bolt/nut assembly.

著者

橋村 真治 伊藤 隼人 小松 恭一 大津 健史

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.61, no.12, pp.882-892, 2016-12-15 (Released:2016-12-15)

参考文献数

14

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It is well known that a main cause of tightening error on the torque control method is changes of the frictional coefficients in thread surfaces and bearing surfaces in bolt tightening. It has been shown in the previous study that the frictional coefficients depend on surface roughness of contact surface, lubrication conditions and bolt configuration errors. The frictional coefficients can be changed by the bolt configuration errors such as a bend of bolt shank and inclination of bolt bearing surface, if large wear and seizure do not occur on the lubricated surfaces.In this study, an influence of the squareness error of bolt bearing surface on the tightening accuracy has been investigated. Results clearly showed that the squareness error of bearing surface causes variations of torque coefficients and the clamping force error. It was shown by FEM analysis that the variation of torque coefficient between bearing surfaces is caused by change of an apparent frictional coefficient. Tightening accuracy also depended on the squareness error of bearing surface.

著者

大津 健史 小松 恭一 橋村 真治 今戸 啓二

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.855, pp.17-00319-17-00319, 2017 (Released:2017-11-25)

参考文献数

27

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This paper describes that the film formation and shear properties of screw tightening lubricant PIB (Polyisobutylene) under the oil starvation condition. The point contacted pure sliding tests were conducted, and the film thickness was measured using the interferometry method with the spacer layer. The result showed that the starvation region occurred at the inlet of the conjunction becomes large with time. It was also shown in the initial time of the test that the film thickness decreases due to the oil starvation, however, the thickness is thicker than the value equivalent to surface roughness. The friction coefficient depended on the starved area, and that showed the constant value of 0.16-0.17 in the fully starved condition. The relationship between the friction coefficient and the shear rate suggested that the coefficient in the high shear rate condition is the constant value, that revealed the film may be changed to the solid like film with the high shear strength in the fully starved condition. The long term test showed that the breakdown of film is appeared at about 120 s and then the wear area expands in the remainder of the test. The test results suggested that the PIB lubrication film has the high shear strength and enable to protect the contact surface in the tightening screw from the direct contact and the wear.

著者

橋村 真治 村上 敬宜

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 C編 (ISSN:03875024)

巻号頁・発行日

vol.68, no.671, pp.2137-2144, 2002-07-25 (Released:2008-02-26)

参考文献数

8

被引用文献数

3

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The clamping force of a bolted joint is usually controlled by torque or angle at tightening. However the fatigue failure of bolted joints occures if the clamping force is loosened in service. Therefore the clamping force in service after tightening must be checked to avoid failure of bolted joints. In this study, a new method to detect the clamping force of bolted joints after tightening has been proposed, in which the clamping force is detected by pulling the protruding thread of the bolt through the nut on a bolted joint. The relationship between the pulling force and the displacement at the pulling point is measured to detect the apparent spring constant of the bolt. When the pulling force reaches the clamping force of bolted joint, the apparent spring constant varies markedly. Thus the clamping force of the bolted joint can be defined on the basis of the variation of the apparent spring onstant. The basic theory and the experimental verifications are presented.

著者

橋村 真治 小松 恭一 藤岡 寛

出版者

一般社団法人日本機械学会

雑誌

年次大会講演論文集 : JSME annual meeting

巻号頁・発行日

vol.2008, no.4, pp.99-100, 2008-08-02

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In this study, influences of lubricants for self-loosening and Fatigue characteristics have been investigated. The self-loosening tests and the fatigue test under transverse vibration were performed using three lubricants, machine oil ISO VG46, MoS_2 grease and special lubricant for bolt tightening. The results showed that the special lubricant for bolt tightening had higher strength for the self-loosening than MoS_2 grease. The results also showed that the apparent transverse fatigue limits using the special lubricant and MoS_2 grease had higher than the apparent transverse fatigue limits using machine oil.