Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load
In a plastic gear pair, the low rigidity of plastics can lead to a higher actual contact ratio due to tooth deflection under load compared to the geometrical one. This phenomenon contributes to a decrease in tooth root stress. The effect of transmitted torque on the actual contact ratio under load i...
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| Language: | English |
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The Japan Society of Mechanical Engineers
2024-12-01
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| Series: | Journal of Advanced Mechanical Design, Systems, and Manufacturing |
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| Online Access: | https://www.jstage.jst.go.jp/article/jamdsm/18/8/18_2024jamdsm0101/_pdf/-char/en |
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| _version_ | 1846106986437935104 |
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| author | Ichiro MORIWAKI Akio UEDA Takao KOIDE |
| author_facet | Ichiro MORIWAKI Akio UEDA Takao KOIDE |
| author_sort | Ichiro MORIWAKI |
| collection | DOAJ |
| description | In a plastic gear pair, the low rigidity of plastics can lead to a higher actual contact ratio due to tooth deflection under load compared to the geometrical one. This phenomenon contributes to a decrease in tooth root stress. The effect of transmitted torque on the actual contact ratio under load is more noticeable in internal gear pairs than in external ones. Therefore, no regard for the contact ratio under load results in evaluating higher tooth root stresses in internal gear pairs. In other words, assessing the bending strength of plastic material through running tests of external gear pairs leads to underestimating the load capacity of internal gear pairs. Consistent tooth-root-stress evaluations in external and internal gear pairs require considering the actual contact ratio under load. The present study proposed a mechanical model applicable to spur gears, which enables considering the effect of the actual contact ratio under load in tooth-root-stress evaluations for plastic gears. This model extends the geometrical contact length by the Hertzian-contact semi-width at the tooth tip and defines the contact ratio under load as the extended contact length divided by the base pitch. Furthermore, the proposed model is also acceptable to helical gears through virtual spur gears with virtual overlap; i.e., an imaginary overlap in the virtual spur gear pair. Introducing a new factor, a contact ratio factor; i.e., the quotient of the geometrical and the actual contact ratios, reduced the evaluated tooth root stresses of plastic internal gear pairs and improved the consistency of the evaluations in external and internal gear pairs. |
| format | Article |
| id | doaj-art-571b7132d0c74d8789be7f927a8fc6ce |
| institution | Kabale University |
| issn | 1881-3054 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Journal of Advanced Mechanical Design, Systems, and Manufacturing |
| spelling | doaj-art-571b7132d0c74d8789be7f927a8fc6ce2024-12-27T01:29:34ZengThe Japan Society of Mechanical EngineersJournal of Advanced Mechanical Design, Systems, and Manufacturing1881-30542024-12-01188JAMDSM0101JAMDSM010110.1299/jamdsm.2024jamdsm0101jamdsmTooth-root-stress evaluation for plastic gears considering effect of contact ratio under loadIchiro MORIWAKI0Akio UEDA1Takao KOIDE2Gear Tech OneAMTEC Inc.Department of Engineering, Tottori UniversityIn a plastic gear pair, the low rigidity of plastics can lead to a higher actual contact ratio due to tooth deflection under load compared to the geometrical one. This phenomenon contributes to a decrease in tooth root stress. The effect of transmitted torque on the actual contact ratio under load is more noticeable in internal gear pairs than in external ones. Therefore, no regard for the contact ratio under load results in evaluating higher tooth root stresses in internal gear pairs. In other words, assessing the bending strength of plastic material through running tests of external gear pairs leads to underestimating the load capacity of internal gear pairs. Consistent tooth-root-stress evaluations in external and internal gear pairs require considering the actual contact ratio under load. The present study proposed a mechanical model applicable to spur gears, which enables considering the effect of the actual contact ratio under load in tooth-root-stress evaluations for plastic gears. This model extends the geometrical contact length by the Hertzian-contact semi-width at the tooth tip and defines the contact ratio under load as the extended contact length divided by the base pitch. Furthermore, the proposed model is also acceptable to helical gears through virtual spur gears with virtual overlap; i.e., an imaginary overlap in the virtual spur gear pair. Introducing a new factor, a contact ratio factor; i.e., the quotient of the geometrical and the actual contact ratios, reduced the evaluated tooth root stresses of plastic internal gear pairs and improved the consistency of the evaluations in external and internal gear pairs.https://www.jstage.jst.go.jp/article/jamdsm/18/8/18_2024jamdsm0101/_pdf/-char/engearsplastic gearsinternal gearstooth root stressload capacitycontact ratiohertzian contact |
| spellingShingle | Ichiro MORIWAKI Akio UEDA Takao KOIDE Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load Journal of Advanced Mechanical Design, Systems, and Manufacturing gears plastic gears internal gears tooth root stress load capacity contact ratio hertzian contact |
| title | Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load |
| title_full | Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load |
| title_fullStr | Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load |
| title_full_unstemmed | Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load |
| title_short | Tooth-root-stress evaluation for plastic gears considering effect of contact ratio under load |
| title_sort | tooth root stress evaluation for plastic gears considering effect of contact ratio under load |
| topic | gears plastic gears internal gears tooth root stress load capacity contact ratio hertzian contact |
| url | https://www.jstage.jst.go.jp/article/jamdsm/18/8/18_2024jamdsm0101/_pdf/-char/en |
| work_keys_str_mv | AT ichiromoriwaki toothrootstressevaluationforplasticgearsconsideringeffectofcontactratiounderload AT akioueda toothrootstressevaluationforplasticgearsconsideringeffectofcontactratiounderload AT takaokoide toothrootstressevaluationforplasticgearsconsideringeffectofcontactratiounderload |