Study On Contact Properties And Kinetic Simulation For Micro-gear Transmission

Micro-gear is a very important part which is used to transmit torque , rotary motion and power in micro-machine and its application covers many fields. Currently, a lot of researches on micro-gear are done and mainly focus on the fabrication of micro-gear, but the researches on the basic design theories of micro-gear hardly exist, for example, the friction between two micro-gears. The following is researched.The stress and strain of micro-gears are induced when they mesh and transmit power. Because of size effect the effect of micro-forces on the stress and strain is taken into account. In this paper, the mathematic model of an optional involute in two dimensions is reasoned and simplified based on Taylor Expression and the simplified mathematic model of an involute is got. Based on the simplified mathematic model, Hamaker Assumption, Morse potential and the cutting-off radius in molecular dynamics, a continuous computational method of van der waals force between the just contacting gear profiles is presented. A program is programmed using Matlab and a series of van der waals forces are computed using this program. Micro-forces are taken into account in the equation used to check the static bending strength of a gear tooth and the corrected equation is obtained. The difference between the results which are got individually using the corrected equation and ANSYS is small.A lot of researches on micro-tribology are done, but the researches on the friction between micro-gears hardly exsit. In this paper, molecular dynamics is utilized to simulate the frictional properties when a pair of nano-teeth only meshed. The results are follows. When a pair of nano-teeth only meshes, the change of the frictional force is similar to one between macro-gears, the fictional force in node isn't 0．When the number of the atomic layer in z direction increases, the maximum of the frictional force is larger and the minimum of the frictional force is smaller, so the curve of the frictional force becomes steeper. When the angular velocity of the powered gear increases, the maximum and the minimum of the frictional force are invariable, but the curve of the frictional force becomes steeper. When the resisting torque increases, the curve of the frictional force doesn't alter.In the end, a mathematic model of a fillet in two dimensions is reasoned, the installation and the kinetic model of planetary micro-gear system are introduced and the kinetic program flow diagram of planetary micro-gear system is drawn. Based on the foregoing, the kinetic program of planetary micro-gear system is programmed by Java. The program can not only manually or automatically design a planetary micro-gear system also be expanded.