| Gear surface temperature is close related with different kinds of gear failure, measuring the gear surface quickly and accurately is of great importance in predicting gear failure and improving the lubrication system design. As a kind of non-contact temperature measurement technique, infrared thermal imaging is becoming more widely used, the accuracy of this technique has also been paid more attention to. In this paper, measurement of oil-jet-lubricated gear surface temperature based on infrared thermal imaging is analyzed.Firstly, mathematical model of infrared thermal imaging is derived, and then factors which influence the accuracy of infrared temperature measurement are analyzed theoretically and experimentally. The influence of surface emissivity, air transmissivity, observation distance and observation angle are analyzed.Secondly, an oil-jet lubricated gear surface temperature measurement test rig is designed. In order to overcome the interference of lubricating oil ejected from the nozzle, the test gears adopted the cantilever arrangement, a temperature measuring hole, a light passing hole and an observation hole are designed on the test gear box. In order to overcome the interference of oil mist, these holes are covered with glasses and blown with compressed air to ensure good visibility.Finally, on the basis of analysis of influencing factors, infrared thermal imager is used to measure the gear surface temperature. In order to improve the accuracy of temperature measurement, the tooth surface emissivity and the transmissivity of the air in test gear box are calibrated. Results showed that tooth surface temperature varied slightly with temperature, and air transmissivity in test gear box varied with oil-jet pressure. Gear surface temperature under different working conditions are measured, the influence of oil-jet pressure, rotation speed and load on gear surface temperature are acquired and analyzed. |
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