摘要
齿轮传动由于受制造和安装误差、齿轮弹性变形及热变形等因素的影响,在啮合过程中不可避免地会产生冲击、振动和偏载,从而导致齿轮早期失效的概率增大。如果对轮齿齿向作适当的修形,对改善其运转性能、提高其承载能力、延长其使用寿命有着明显的效果。因此利用先进的计算分析软件——ANSYS对轮齿的齿向修形进行研究具有特别重要的意义。本文利用有限元方法,就直齿圆柱齿轮的修形参数对轮齿啮合过程中接触线上载荷分布的影响进行了认真深入的分析,建立了一种寻求最优齿向修形参数以获得合理齿向形状使齿向载荷分布均匀的方法。
本文利用ANSYS有限元软件,建立直齿圆柱齿轮三维参数化有限元模型。整个三维模型通过APDL自动生成,实现了有限元分析模型的参数化,可以快捷方便地对不同修形参数的齿向形状进行有限元计算和分析。
对直齿圆柱齿轮接触线上的应力分析表明,接触应力沿接触线方向分布不均匀,且在接触母线的端点处存在较大的应力。为使在接触区内应力沿接触线方向分布较均匀,需改变不同的齿向形状参数,对齿向形状进行优化分析。
本文采用二次曲线作为鼓形齿的修形曲线,考虑鼓形量对曲线的约束,运用零阶优化算法,建立了修形齿轮的数学模型,对接触轮齿进行形状优化。优化结果显示:进行接触轮齿齿向方向的形状优化后,最大应力值减小并且应力分布比较均匀,大大提高了轮齿的接触强度,为工程设计提供了有力的依据。本文还采用文献[2]中的中央鼓形曲线对接触轮齿进行形状优化,其优化结果与二次修形曲线的优化结果进行比较。得出结论:采用二次曲线对轮齿进行优化的优化结果要略优于用中央鼓形曲线对轮齿进行优化的优化结果。从而验证了用二次曲线对轮齿进行优化的优越性。
Shock, vibration and offset load are generated unavoidably during gear transmission period due to the influence of manufacturing error and setting up error, elastic deformation of gear, hot deformation and so on, which lead to increase probability of early failure of gear. If shape of gear along gear trace were modified , transmission performance and bearing capacity would have been improved and service life would have been prolonged. Therefore, it is very important to study shape optimization of gear by means of modern computer analysis software—ANSYS. According to the effect of the parameters to the load distribution along the contact line of spur gear,this paper applies the finite element method(FEM) to analysis and study further,in order to establish a method of the correct shape along contact line by finding the optimum shape parameters.
In this paper, the three dimensional parameterized FEM model of spur gear is established by ANSYS. The three dimensional model is generated automatically by APDL, which accomplish the parameterized FEA model. It can be analyzed by FEM efficiently and conveniently on the shape along gear width of different shape parameters.
According to stress analysis of contact line, contact stress along contact line is not equally distributed, and the bigger stress concentration is produced on the two sides of the contact line. In order to distribute equally stress on the contact line, the shape parameters are changed and the shape of tooth trace is optimized.
Shape of contcact gear is optimized using zero-stepped method by adopting quadratic curve as shape-modified curve, considering restriction of the drum-shaped quantity to it and establishing the mathematical model .The result of optimization is displayed : the max stress value of contact line is decreased and stress value is equally distributed on contact line after optimization the shape of gear,which enhanced contact strength of gear and providing the evidence for engineering design .the paper also adopt the central drum-shaped curve of document [2] to optimize the shape. Compared with the optimization result of quadratic shape-modified curve, the optimization result of quadratic shape-modified curve is predominant in the stress distribution of contact line.
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