The Profile Modification And Dynamics Simulation Analysis Of The Small Involute Gear

Due to its constant ratio and stable transmission, involute cylindrical gear is widely used in mechanical transmission, however, when the gear pair meshing, the load mutations, speed fluctuation and meshing impact are brought about inevitably by the factors:deformation caused by load, thermal deformation, manufacture and installation error and etc. A large number of theory and practice has shown that tooth profile modification can obviously reduce agglutination and shock, decrease the vibration and lower noise when gear pair meshing to make gear transmission technology better adapt to the development trend of high load, high speed and low noise. However, in previous research on profile gear modification, modification technology of "modification of tooth addendum and dedendum" was adopted, namely part of the profile was modified, at the same time the starting point, end point, degree and curve of modify, etc. were identified. The factors needed to control are more, which will bring about troubles to actual processing and is difficult to meet precision requirements. The new shock on the starting point and the end point of gear modification is also formed when the modified gears is meshed.According to deficiency in traditional gear modification, the similarity between arc decayed curve and involute is discovered by researching a large number of curve. Most importantly, arc decayed curve is of easy processing and nobody has tried to modify tooth profile using this curve. The method that arc decayed curve is approached to modify tooth profile by approximating gear involute is tried in this paper and the aim is to explore the method of tooth profile which is more suitable for the engineering practice.The main content of this paper is as follows:1. Modeling, loading and solving of finite element model for Standard gear is accomplish by APDL programming language. The entire process automatically generates through APDL language which can make alterations on model and load case expediently. The method avoiding another analysis software's effect not only can raise the efficiency of analysis but also proceed the process of analysis under ANSYS.2. Standard involute spur gear is simulated by ANSYS/LS-DYNA explicit dynamics software. It points out the distribution rule of gear contact stress of tooth profile. According to an analysis of the change regularity of the gear contact stress under different speeds, the necessity that tooth profile of the high-speed gear is modified is pointed out. Finally, the rule of driving and driven gear's speed fluctuations in gear transmission is researched. The results that ANSYS/LS-DYNA simulates the gear dynamic engagement process and reflects dynamic engagement characteristics of gear by the greatest degree indicate accurate and reliable. 3. The whole process of tooth profile for gear by arc decayed curve is introduced in particular. It analyzes the modified gear with dynamic simulation. By contrasting the contact stress distribution of the modified and standard gear and the speed fluctuation of the driving and the driven gear, it Draw a conclusion that tooth profile for gear by arc decayed curve can improve the performance of gear transmission.4. For obtaining the vibrating mode of the modified gear pair, the method of adopting coupling DOFS of nodal and contact are individually applied to modal analysis. Natural frequency and vibrating mode of the first 18 order are drew and analysed. At last, the effect of width of tooth for natural frequency of gear are analysed.