http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Vibration and Noise of Gears of Damping Alloy
Oda, Satoshi,Koide, Takao,Shimizu, Hisao,Miura, Kenzo 대한기계학회 1996 International Sessions in Celebration of the 50th Vol.1 No.1
This paper presents a study on vibration and noise of gears of damping alloy. The logarithmic decrements of damping alloy were measured and compared with those of conventional steel. Vibration acceleration and sound pressure of helical gear pairs and spur planetary gear units of the damping alloy were measured under various running conditions using a power-absorbing-type gear testing machine, and the results were compared with those for conventional steel gears. Furthermore, the sound intensities of planetary gear units of damping alloy and conventional steel were also measured. The vibration and noise characteristics of these gears were determined.
Bending fatigue strength of case-carburized helical gears (In the case of large helix angles)
Kengo Nojima,Kengo Ogata,Motomu Tanaka,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12
Case-carburizing enlarges the depth of the hardened layer at the tooth width end on the acute angle side of helical gears. For the helical gears with large helix angles (Exceeding 25°), this hardened layer may lower their bending fatigue strength. Therefore, we investigated the influence of this hardened layer on their bending fatigue strength through the bending fatigue tests. Our results suggest that this hardened layer might reduce the case-carburizing’s effect to enhance their bending fatigue strength. Thus, using only the maximum tooth root stress would be inadequate for evaluating their bending fatigue strength, and it would be necessary to consider the relationship between the hardened layer and the tooth root stress distribution (Especially, the stress applied at the tooth width end on the acute angle side) from the beginning of meshing to the end.
Bending fatigue strength of case-carburized helical gears with large helix angles up to 40 degrees
Mikiya Yamaoka,Motomu Tanaka,Masaya Kumada,Kengo Nojima,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12
Case-carburizing of helical gears with large helix angles may form too large hardened layers near the tooth width end on the acute angle side (ACUTE-END), and adversely affect the bending fatigue strength. We investigated the bending fatigue strength of casecarburized helical gears with large helix angles up to approximately 40° through a bending fatigue test, hardness test, and residual stress measurement. We found that the case-carburizing formed large hardened layers near ACUTE-END, reduced the compressive residual stress near ACUTE-END, and restricted the improvement of the bending fatigue strength in a meshing state where tooth root stress became large near ACUTE-END. Based on the obtained bending fatigue limits, we revealed that ISO 6336-3:2006 overestimated the rate of increase of the permissible circumferential loads for helix angles exceeding approximately 30°, and ISO/DIS 6336-3:2018 underestimated this rate for helix angles near 30°.
Tomoaki Ikuta,Kazuyoshi Takahama,Kengo Nojima,Ryosuke Nishi,Yuichi Ono,Takao Koide 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12
Discarding case-carburized gears with excessive case-depth causes financial and environmental losses. To save the losses, we experimentally investigated the applicability of case-depth modification by additional heat treatments (AHTs) to such gears in terms of bending fatigue and impact strength. The AHTs consisted of an intermediate softening treatment (IST) (vacuum normalizing, tempering, induction normalizing, or none) to case-carburized spur gears with an excessive case-depth, followed by induction heating and quenching. All the AHTs reduced the effective case-depth, maintained the surface residual stress, refined the microstructure near tooth root surfaces, and maintained the bending fatigue limit. Moreover, all the AHTs increased the impact limit because of the refinement of the microstructure, whereas omitting an IST reduced this increase. Thus, case-depth modification by AHTs is applicable in terms of bending fatigue and impact strength, and conducting an IST is highly recommended.