The contact spots of three new bevel gears are shown in Figure 1. It can be seen that for single point contact conjugate curve bevel gears, the contact spots are still located in the middle of the tooth surface after assembly. For the multi-point contact bevel gear, after assembly, its tooth surface shows a contact line, which shows that the multi-point contact conjugate curve bevel gear is more sensitive to error. However, in the process of light load operation, the vibration of single point contact conjugate curve bevel gear is greater than that of multi-point contact conjugate curve bevel gear, which shows that multi-point contact conjugate curve bevel gear has greater advantages than single point contact conjugate curve bevel gear in terms of operation stability.
After the tested gearbox is running and, replace the lubricating oil in the gearbox and clean the gear pair and box, and conduct efficiency test on the prototype under different working conditions. The test conditions are as described in subsection 6.3.1: the input speeds are 500 R / min, 750 R / min, 1000 R / min and 1200 R / min respectively; The output torques are 54nm, 108nm, 162nm, 216nm, 270nm, 324nm, 378nm, 432nm, 486nm and 540nm respectively. Under the above conditions, the transmission efficiency and temperature rise of conjugate curve bevel gear are tested, and the test results are shown in Fig. 2 and Fig. 3. In simultaneous interpreting the traditional arc bevel gears, the experimental results of arc efficiency and temperature rise under the same working conditions and SEW V230 decelerator are shown in figures 2 and 3.
It can be seen from the test results that when the load is low, the transmission efficiency of the gearbox is also low. This is because under low load, the inherent power loss of the system, such as oil mixing loss and bearing friction loss account for a large proportion. With the increase of load, the inherent power loss of the system is basically unchanged, and it gradually decreases in proportion in the power flow. Therefore, the transmission efficiency of the gearbox is also gradually increasing. At this time, the transmission efficiency is gradually approaching the transmission efficiency of the gear body under this lubrication condition.
It can also be seen from the test results that basically, when the speed is low, the transmission efficiency of the gearbox is low, and with the increase of the speed, the transmission efficiency is gradually increasing. This phenomenon can be explained in tribology. In tribology, there is a formula for calculating the minimum oil film thickness of Dowson Higginson:
In the above formula, α 1 represents the viscosity pressure coefficient of lubricating oil, η 0 represents the viscosity of the lubricating oil under the current ambient pressure, u represents the average entrainment speed, e ‘represents the converted elastic modulus, R represents the relative radius of curvature, and W represents the load per unit length.
It can be seen from the formula that with the increase of speed, the average entrainment speed increases, so the minimum oil film thickness increases and the lubrication conditions are improved, so as to reduce friction loss and improve transmission efficiency.
When the load reaches the rated working condition of the reducer, the transmission efficiency of pure rolling contact bevel gear is 98.2%, that of equiangular helix non pure rolling single point contact bevel gear is 96.6%, and that of five point contact equiangular helix bevel gear is 96.8%. It can be seen that the transmission efficiency of conjugate curve bevel gear is still high under general assembly conditions. This is because the theoretical contact point of conjugate curve bevel gear is controlled near the pitch line. In this area, the relative sliding speed between the two tooth surfaces is small, and the friction loss between the tooth surfaces is small, so the transmission efficiency is high.
During operation, the oil temperature in the reducer is shown in Figure 3. It can be seen that when the tested reducer reaches the rated power, its oil temperature is closely related to the transmission efficiency. When the transmission efficiency of the tested reducer is high, its oil temperature is low, and when the transmission efficiency of the reducer is low, its oil temperature is high. This is because the temperature rise of lubricating oil is mainly caused by the internal friction loss of the tested reducer. The lower oil temperature of conjugate curve bevel gear also reflects the higher efficiency of conjugate curve bevel gear compared with traditional circular arc bevel gear.