Under the ideal oil lubricated meshing condition, the big and small gear teeth will be completely separated by the oil film. At this time, the two tooth surfaces do not contact and the friction coefficient is very small, so there will be no scuffing or wear. However, in the actual meshing process, if the elastohydrodynamic oil film between gear teeth is thin, the two gears will inevitably contact directly, which may lead to tooth surface wear and scuffing. Because scuffing failure is transient compared with pitting and fatigue fracture with obvious development cycle, it is necessary to avoid gear scuffing failure through flash temperature study.
Figure 1 shows the flash temperature curve of helical gear pair of No. 0 unmodified, No. 1 optimization scheme and No. 9 optimization scheme. It can be seen that the flash temperature of helical gear pair after modification of No. 1 optimization scheme has decreased significantly as a whole, and the peak temperature has decreased from 15.85 ℃ before modification to 10.62 ℃ after modification, down 5.23 ℃; Although the flash temperature peak temperature of the meshing section (CE) of the helical gear pair modified by the No. 9 optimization scheme has not decreased, the meshing section (AC) overall decreases significantly, because a pair of gears will first engage at the root of the driving gear and the top of the driven gear, while the No. 9 scheme is to improve its meshing performance by modifying the top of the driven gear. Therefore, it can be considered that the instantaneous meshing temperature of helical gear pair after optimized modification is significantly reduced, which effectively avoids the occurrence of thermal deformation of tooth profile and scuffing failure.
The tooth surface contact temperature is the sum of the helical gear temperature (greatly affected by the lubricating oil temperature and average flash temperature) and flash temperature, and is an important indicator reflecting the relative sliding degree of the meshing gear pair. Figure 2 shows the contact temperature curve of helical gear pair tooth surface of No. 0 unmodified, No. 1 optimized and No. 9 optimized schemes. It can be seen from the figure that the tooth surface contact temperature of helical gear pair after the modification of No. 1 optimization scheme decreases significantly, the maximum value is 74.87 ℃, which is 4.6% lower than that before the modification (78.44 ℃); As the No. 9 optimization scheme only modifies the passive wheel, the temperature of the meshing section (CE) does not decrease, but the meshing section (AC) decreases significantly.