Performance Analysis Of Heavy-Duty Gear And Research On Structural Optimization

Heavy-duty gear is widely used in various engineering machinery. In order to meet the demand of heavy load in large-scale projects, the original advantages of involute gear need to be maintained, carrying capacity need to be further improved, and dynamic load and impact in the complex condition is minimized. On the basis of understanding the heavy load gear transmission performance, optimizing the gear structure is suggested. At present, many scholars tend to study transient impact or steady-state gear contact. It is not comprehensive to understand the whole tooth surface dynamic contact performance.In this paper, by taking hub reducer gear in a certain type of excavator as the research object, in order to improve gear carrying capacity and transmission stability, combined with the result of dynamic analysis, contact analysis and thermal-structure coupled analysis, profile modification and longitudinal correction is done. Then operating the thermal contact analysis again is used to verify the feasibility of the modification. Thus, the main work of this paper is summarized as follows.1. The mathematical model and physical model of cylindrical gear contact are established. The gear space mesh mathematical theory is applied, and obtaining the gear contact model in rectangular coordinate system. Furthermore the basic theory of contact mechanics is used in gear contact.2. Based on the finite element analysis software ABAQUS, the technology of contact analysis and thermal-structure coupled analysis are implemented. First of all, to discrete the gear model; then, to judge the contact state constantly on the discrete entity model according to FEM; finally, to solve the contact state equation, the contact stress and displacement. In addition to this, thermal-structure coupled analysis need to solve temperature field. And then, in the same boundary and load, using the way of refined grids and calculation, the accuracy of finite element calculation is verified.3. The amount of deformation and tooth contact line stress curves are extracted from the finite element calculation results. That is used to understand the contact stress distribution of the whole tooth surface in the process of contact. And the main areas of modification are determined. Using the maximum amount of deformation in odd teeth alternately engaging as the main parameters, the maximum amount of modification is determined.4. Summarizing the existing modification programs, combining with the results of the finite element calculation, profile modification and longitudinal correction is applied to the sun gear tooth. Finally, a set of modification parameters for heavy load working conditions are proposed. And the modification sun gear model is created.In this paper, the whole tooth surface contact analysis and thermal-structural coupled analysis based on contact are practiced by FEM. Five contact lines are determined according to the AGMA standard, which are used to reflect the whole tooth surface contact stress distribution. The results of performance analysis give directions to heavy duty gear modification. And a set of modification parameters used for the very model are proposed.