| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 94 === The circular-arc curvilinear-tooth gear, which has curvilinear trace with circular-arc profile, is generated by a circular-arc disk-type cutter.
Gears with curvilinear traces ensure that the gear pair is operated in a point contact condition, which is different from the line contact type of a helical gear pair or spur gear pair. The point contact condition can not only avoid the tooth edge contact, decreases the kinematical errors and vibro-acoustic due to axial misalignments, but also increases the bearing strength of the contact gears. Moreover, a gear pair with curvilinear-tooth traces operates without axial thrust force.
The helical gears with circular-arc profile are used for transmitting with high load circumstance, because their loading capacity and lubricity are better than those of conventional helical gears. However, the circular-arc helical gear pair is quite sensitive to the central distance assembly errors.
This study adopts the rack cutter with circular-arc profile to modify the profile of involute-type curvilinear-tooth gear pair. The gear surface is generated by an imaginary circular-arc rack cutter with a curvilinear trace. According to theory of gearing, a mathematical model of the gears with circular-arc profile and curvilinear-tooth trace is developed. The undercutting of the gears can be avoided by a positive profile-shifted modification during the gear set generation process. The tooth contact analysis technique is utilized to the investigation on kinematical errors, contact ratios and contact patterns of the gear set under axial misalignments.
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