Meshing Characteristics Analysis of POM Gear Based on Thermoelastic-viscoplastic Constitutive Model

In order to reveal the influence of load, modification and temperature on the meshing characteristics of POM–POM gear pair, a three-dimensional finite element contact model of POM–POM gear pair based on thermoelastic-viscoplastic material constitutive model was established. At the same time, combined with the temperature-modulus effect of POM material, the steady-state thermal analysis of temperature-stress sequential coupling was carried out, and compared with the temperature service test results of POM–POM gear pair. Based on the steady-state thermal analysis, the fully coupled transient thermal contact analysis was carried out, and the transient temperature rise was compared with the Blok temperature results. Through the tooth root strain test, the validity of the tooth root strain calculation under different load conditions is verified. The results show that the steady-state temperature rise of the gear pair presents the distribution law of high tooth root, low tooth top and end face, and increases with the increase of load. Through the test comparison, the steady-state temperature rise of the gear calculated by the finite element method is consistent with the test results, and the transient temperature rise is consistent with the Blok formula. At the same time, the simulated tooth root strain of POM–POM gear pair is located in the strain error band of the experimental test, which shows that the thermoelastic-viscoplastic material constitutive considering the temperature-modulus effect can characterize the thermal and mechanical properties of POM plastic gear. In addition, the meshing line of POM–POM gear pair is extended and deviated from the theoretical position during the transmission process, and the temperature has little effect on the meshing line. The tooth surface modification can reduce the length of the meshing line, but can not improve the deflection degree. The meshing angle will change greatly when it is in and out of the meshing, and the temperature makes the meshing angle rise about in the double-tooth meshing area. The meshing stiffness is related to the load. As the load increases, the meshing stiffness decreases and the coincidence degree increases. Under the same conditions, the transmission error amplitude of POM–POM gear pair is about 10 times that of metal gear pair, and the temperature increases the transmission error amplitude by about 39%, and the tooth surface modification can reduce the transmission error amplitude by about 24%.