Corrective measures

According to heat treatment process inspection and finite element calculation results, the transmission staggered helical gear is quenched and cast in sand mold, and the contact stress on the tooth surface exceeds the surface fatigue limit.Considering the surface hardening and centrifugal casting processes for the staggered helical gears of the parent type, the manual shows that the tooth surface fatigue limit Hlim=425MPa is larger than the calculated contact stress, which meets the requirements of application.

Therefore, improvement measures are taken for staggered helical gear: the driving wheel of staggered helical gear is changed to 20Cr Mn Ti, the tooth surface is carburized and hardened, and the driven wheel is ZCu Sn10P1, centrifugally cast.

Test verification

After replacement of transmission staggered helical gears with rectification measures, the unit carries out 500-hour operation test, in which there are checking items for changing high and low operating conditions.When the high and low operating conditions are changed, the speed of the helical gear drive wheel increases from 1930r/min to 2900r/min in a few seconds or changes in the opposite direction, and 100 times of bi-directional conversion are accumulated in the test.

After these rigorous test examinations, the staggered helical gears are disassembled and inspected as shown in the figure and the tooth thickness is measured.The tooth surface traces and tooth thickness measurements show that the staggered helical gears are wear-free and the corrective measures taken are reasonable and effective.