| As a new type of cylindrical gear,the involute thick gear has many advantages such as smooth transmission,high load capacity,high precision and automatic gap adjustment,etc.It has wide application prospects and obvious technical advantages in power transmission fields such as speedboats,precision robots and full-drive automobiles.However,due to the special tooth surface shape of variable-thickness gears,their dynamic meshing behavior is very complex,which seriously restricts the application and development of variable-thickness gears.Therefore,a systematic analysis of the dynamic meshing behavior of variable-thickness gears has become a key issue in their application development.This topic takes the parallel axis involute variable tooth thickness gear as the research object,and adopts a combination of theoretical calculation,simulation and transmission test to analyze the dynamic meshing characteristics of the involute variable tooth thickness gear transmission system in a more systema tic way.The specific research contents of the thesis are as follows:(1)Based on the principles of gear meshing and gear geometry,the tooth surface equation of the involute variable tooth thickness gear is derived.Using gear surface reconstruction and discretization techniques,a relatively accurate digital model of the gear is constructed,laying the foundation for subsequent analysis.Secondly,the ADAMS virtual prototype simulation software is used to establish a dynamic simulation model of the variable tooth thickness gear and to explore the variation law of dynamic meshing force under different working conditions(damping,load,stiffness,rotational speed).(2)According to Hertz contact theory,the improved calculation formulas of contact stress and bending stress are derived,and the influence of different design parameters on contact stress is analyzed.The finite element simulation software is used to establish the load-bearing contact model of the involute variable tooth thickness gear.Through the finite element loading analysis,the variation law of the normal force and the comprehensive elastic deformation on the working tooth surface is obtained.At the same time,the time-varying excitation characteristics such as time-varying meshing stiffness and transmission error are studied,and the evolution law of geometric design parameters on time-varying excitation characteristics is discussed.Finally,using the GUI interface design function,the design and analysis program of the variable tooth thickness gear is packaged,and the design and analysis system module of the variable tooth thickness gear is obtained.(3)Based on the theory of elastic contact dynamics,the meshing impact model of involute variable tooth thickness gear is established to study the variation law of impact stress and impact force of gear teeth under different rotational speeds and different impact positions,so as to analyze the distribution of meshing characteristics of variable tooth thickness gear.The results show that with the increase of rotational speed,the impact force and impact stress show an increasing trend,but at different impact positions,they show the opposite variation law,which indicates that the gear meshing impact state is related to rotational speed,load and contact form.(4)Based on the five-axis linkage machining center,the solid model of the gear is processed,and the accuracy of the processed gear is tested.The point cloud data is compared with the 3D model to ensure its machining accuracy.At the same time,an involute variable tooth thickness gear transmission test bench is built.Through data acquisition at the input end and data analysis at the output end,the variation law of transmission error at different speeds is obtained.The results s how that the experimental results are consistent with the theoretical analysis,which verifies the correctness of the geometric design,transmission characteristics and related theoretical research of the involute variable tooth thickness gear.The above research provides a theoretical basis for the study of dynamic contact meshing characteristics of involute variable-thickness gears,which can provide a certain scientific reference basis for the optimal design of gear teeth and industrial applications. |
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