1991 Fiscal Year Final Research Report Summary
Research on Austempered Ductile Iron Gear
| Project/Area Number |
02555035
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械要素
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| Research Institution | Kyushu University |
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Principal Investigator |
ARIURA Yasutsune Kyushu Univ., Faculty of Eng., Professor, 工学部, 教授 (10038044)
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| Co-Investigator(Kenkyū-buntansha) |
UMEZAKI Yoji Kyushu Univ., Faculty of Eng., Research Associate, 工学部, 助手 (70038066)
YANO Mitsuru Oita Univ., Faculty of Eng., Professor, 工学部, 教授 (10230286)
NAKANISHI Tsutomu Miyazaki Univ., Faculty of Eng., Professor, 工学部, 教授 (40038055)
ODA Satoru Tottori Univ., Faculty of Eng., Professor, 工学部, 教授 (50032016)
OZAKI Tatsuo Kyushu Univ., Faculty of Eng., Professor, 工学部, 教授 (40037742)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Austempered ductile iron / Gear / Hyobbing / Rolling / Load-carrying capacity / Bending fatigue strength / Tooth surface durability / Tooth surface failure |
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| Research Abstract |
This research aims at investigation of the strength and the machinability of austempered ductile iron (ADI) for its application to gears.
1. Development of the new ADI ; By investigating the metallic structures and the mechanical properties of new ADI, the ADI that has enough strength and superior machinability for gear material is developed, that is, the mechanical properties are 100Kgf/mm^2 in tensile strength, 10% in eloggation, 300 in Brinell hardness and the number of graphite grains is approximately 250/mm^2.
2. Machinability tests ; (1) Hobbing tests ; The hob with relief angle of 15ﾟ and rake angle of 5ﾟ and/or the cooling of the hob teeth by the compressed air are effective in the improvement of hob life. The ADI gears finished with a cermet finishing hob result in JIS class 0 in tooth profile accuracy and Rmax 2-3mum in tooth surface roughness. In fundamental tests using a fly-tool, this ADI is able to be cut at cutting speed of 100m/min. (2) Rolling of the tooth fillet ; The m
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ethod and the conditions of the rolling of the tooth fillet are investigated in detail. The rise of the surface hardness of the ADI gear rolled is shown, which has a great influence on the bending fatigue strength of gear teeth.
3. Load-carrying capacity ; (1) Bending strength ; In bending fatigue tests with a pulsator, the bending strength of the hew ADI is sufficient for the gear material. The bending strength of the ADI gear after shot-seening treatment is nearly equal to. that of the carburized steel gear. (2) Tooth surface durability ; Roller tests using a 2-roller-type fatigue tester clarifieds that the increase of the surface hardness of the ADI gear contributes to improvement of the surface durability, and that the number of graphite grains relates to the surface damage of the ADI gear. Gear tests represents that the ADI gears hobbed have sufficient surface durability, and that the durability increases by finishing the ADI gear with the cermet hob.
4. Conclusions ; The new ADI concerned is possible to be manufactured as a gear material efficiently by the optimization of tool materials and tool geometries and the cutting conditions in manufacturing aspects. The ADI has sufficient strength in the region of medium hardness gears in aspects of the material strength. The Improvement of the tooth surface roughness with the cermet finishing hob and the work-hardening of the tooth fillet by the rolling and the shot-seening represent the possibility of application of the ADI gear to the region of high hardness gears such as case-carburized or inductionhardened gears. Less
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