Transient Thermal Analysis Of Spiral Bevel Gear Under The Condition Of Dry Operation

The transmission system of a military helicopter comes into the oil-free working condition, as it is shot and leaking, which may cause failures such as locking or agglutination. The gear transmission system will lose transmitting ability in a short time, which in turn may cause the clash of the helicopter.It is significant to study how to improve the ability of the transmission system to run without oil and how to ensure at least 30 minutes transmitting ability under the condition of losing lubrication when leaking, which may reduce financial loss and guarantee the safety of the crew.As they are widely used in military helicopters, this paper conducts a study about spiral bevel gears. This paper obtains the distribution of transient temperature field on the tooth surface of gears through solving partial differential equation of 3D transient thermal conductivity, based on the principle of gear engagement, on the theory of heat transmission and on tribology, by means of combining theoretical analyzing computation and the finite element analysis. The main points of this paper are listed as follows:1. This paper establishes a solid model of one tooth under ANSYS0.0 according to the equation of the tooth surface of the spiral bevel gears, which is then transformed into a finite element one by means of mapped meshing.2. This paper respectively computes the convective heat transfer coefficient of the incoming side, the end and other sides of gears under the condition of dry operation. It also makes contrast analysis of the changing trends of the convective heat transfer coefficient which may vary with different temperature and speeds.3. This paper computes the relative sliding friction coefficient and defines the heat source intensity of the tooth surface friction under the condition of dry operation by employing the basic meshing principle of spiral bevel gears, tribology and the theory of heat transmission.4. This paper also computes the transient temperature field of the tooth with ASNSYS10.0 using the heat flux and convective heat transfer coefficient as the incoming surface loading, and describes the principle that the temperature at the crucial point of meshing trace on the tooth surface varies with time.5. According to the theory of Block flash temperature, this paper analyzes the temperature raising curve of the meshing point at two different speed when the pinions rotate and finds out the time when the scuffing failure of the tooth surface happens. The study presents a reference for the predication of the spiral bevel gears'lifespan under the condition of oil-free lubrication.