http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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°.
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.
( Shinji Ishii ),( Suguru Fukahori ),( Kimio Asagiri ),( Yoshiaki Tanaka ),( Nobuyuki Saikusa ),( Naoki Hashizume ),( Motomu Yoshida ),( Daisuke Masui ),( Naoko Komatsuzaki ),( Naruki Higashidate ),( 대한소화기기능성질환·운동학회(구 대한소화관운동학회) 2017 Journal of Neurogastroenterology and Motility (JNM Vol.23 No.4
Background/Aims The aim of this study is to investigate the degree of delayed gastric emptying (DGE) and evaluate how the severity of DGE affects gastroesophageal reflux disease (GERD) in neurologically impaired (NI) patients utilizing 24-hour multichannel intraluminal impedance pH measurements (pH/MII) and <sup>13</sup>C-acetate breath test (<sup>13</sup>C-ABT) analyses. Methods <sup>13</sup>C-ABT and pH/MII were conducted in 26 NI patients who were referred to our institution due to suspected GERD. At first, correlation analyses were performed to investigate the correlation between the <sup>13</sup>C-ABT parameters and the clinical or pH/MII parameters. Thereafter, all patients were divided into 2 groups (DGE and severe DGE [SDGE] group) according to each cut off half emptying time (t<sub>1/2</sub>, 90-170 minutes). Each pH/MII parameter was compared between the 2 groups in each set-up cutoff t<sub>1/2</sub>. Results The mean t<sub>1/2</sub> of all patients was 215.5 ± 237.2 minutes and the t<sub>1/2</sub> of 24 (92.3%) patients were > 100 minutes. Significant moderate positive correlations were observed between both t1/2 and lag phase time and the non-acid reflux related parameters. Furthermore, the patients in the SDGE group demonstrated higher non-acid reflux related parameters than those of the DGE groups when the cutoff was t<sub>1/2</sub> ≥ 140 minutes. Conclusion The present study demonstrated that GE with t<sub>1/2</sub> ≥ 140 minutes was related to an increase of non-acid exposure reaching up to the proximal esophagus in NI patients, and indicating that NI patients with SDGE might have a high risk of non-acid GERD. (J Neurogastroenterol Motil 2017;23:533-540)