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This paper is mainly to study and test wear and accuracy of gear tooth surface of spur gear group and helical gear group after generation of operational wear. The wear of gears usually occurs under long operating time and high load. In this study, two planetary reducers of experiment groups A and B and two planetary reducers of control groups C and D were used to carry out comparison. Under the circumstances of same frame diameter and same specific speed, this study designed and manufactured the spur gear planetary reducers and helical gear planetary reducers separately, and confined axial movement space of the three planetary gears inside the reducers in order to reduce the factors of effect such as axial thrust when helical gear is running. Operating under same material, same modulus, same gear accuracy level, using same lubricating grease, same heat treatment and same rated load, and through same test conditions and method, this study examined and observed the relative wears of spur gear and helical gear and made comparisons, and improved shortcomings of experimental groups through changing gear crowning design. Through researching and understanding that helical gear would generate axial thrust in a confined space, and its gear engaging contact line of helical gear is longer than that of spur gear, this study investigated whether wear speed of helical gear is the same as that of spur gear. Through analyzing the experimental data obtained from 18 million revolutions of actual test, it is confirmed that under the circumstances of confined space and generating axial thrust, the average wear rate of tooth surface of helical gear groups is not faster than that of spur gear groups. However, the positioning error accuracy of helical gear groups changed 9.88 arc minutes from 1.46 arc minutes before operation to 11.34 arc minutes after load operation. Although it could be slightly retarded through changing tooth profile of experiment groups after trimming 0.01mm of design, there is still an obvious gap compared to the change of approximately 2 arc minutes of positioning accuracy of spur gear before and after operation.
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