【作者】 张亮；

【导师】 冯玮；

【作者基本信息】 武汉理工大学 ， 材料科学与工程， 2016， 硕士

【摘要】 准双曲面齿轮与一般的弧齿锥齿轮主要差别在于小齿轮的偏置,可以用于实现交错轴的运动以及动力传递。准双曲面齿轮可以实现双跨支撑,在传动比较大时增加小轮直径从而增强小轮刚度和齿轮副强度,提高齿轮副在传动过程中的稳定性。准双曲面齿轮多用于转速较高或者载荷较大的关键传动系统当中。工作环境使其在传动过程中具有较大的啮合接触冲击力,因此准双曲面齿轮啮合传动动力学特征的研究对于提高齿轮副啮合传动性能具有重要指导意义;齿根裂纹是轮齿疲劳断裂问题研究的主要对象之一,目前关于齿根裂纹问题的研究主要集中于裂纹前缘应力强度因子的有限元仿真计算,很少有研究涉及到啮合接触冲击状态下齿根弯曲应力的变化;另外由于准双曲面齿轮具有复杂的空间几何特点,齿轮副三维造型比较困难,在进行以上分析之前,必须建立准确、有效的准双曲面齿轮副三维模型。基于准双曲面齿轮应用研究中存在的这些问题,本文完成了以下工作,并得到了相应的研究结果:(1)提出了一种基于布尔运算的小齿轮造型方法,并建立了齿轮副三维模型。根据准双曲面齿轮的加工方法,结合啮合原理,利用MATLAB计算出了齿轮坯几何参数以及大轮齿面离散点参数,并通过三维造型软件建立了大齿轮的三维实体模型;基于准双曲面齿轮副中齿轮的空间相对位置关系,利用布尔减运算功能完成了小齿轮的三维造型。通过装配干涉以及动力学特性分析验证了齿轮副传动性能的可靠性。(2)研究了准双曲面齿轮传动的动力学特性以及啮合力的影响因素,揭示了摩擦、转速等对啮合冲击的影响。在齿轮副三维模型的基础上于Adams中建立了准双曲面齿轮动力学特性分析有限元模型,详细研究了摩擦条件和转动速度等在对啮合力的影响;并研究了啮合过程中瞬时冲击状态下啮合冲击力的特点。研究发现,啮合冲击剧烈程度随着转速的增加而迅速增加,随着载荷的增加逐渐降低;而摩擦对啮合冲击的影响比较微弱。(3)分析了啮合冲击对齿根弯曲应力以及齿根裂纹的影响。在ANSYS分析了齿轮静态接触时的齿根弯曲应力;利用Adams分析了动态接触状态下小齿轮的有效转矩,并计算了在此情况下的齿根弯曲应力;对比分析了啮合接触冲击对齿根弯曲应力的影响;并简要分析了啮合接触冲击对齿根裂纹的影响。研究发现啮合冲击对齿根弯曲应力的影响十分明显,在主动轮达到一定转速时,齿根弯曲应力值可以达到静弯曲应力的两倍。这也会对齿根裂纹产生明显的影响。更多还原

【Abstract】 The difference between hypoid gears and spiral bevel gears lies mainly at the offset of the pinion,and it is also why the hypoid gears can be used to transmit power and motion between alternating axes.Besides of the transmissioncharacteristics shared with spiral bevel gears like steadiness,efficiency and high bearing capacity,a hypoid gear set has some unique advantages because of the pinion offset.Thestiffness of the pinion grows as itsradius increases,moreover,when the transmission ration is large enough,a two sides support of the gears can be achieved as the strength of the gear set would be extended.A hypoid gear set is always used in a key systemin working environment of high speed and heavy load,which would lead to higher meshing stress.So the analysis of hypoid gear set transmission characters and the prediction of root crack growth can be an active guide to the designing,manufacturing and use of it.The root cracks of gear are one of the key points of gear fatigue failure,while the research of this problem has seldomreached the field of meshing impact.Also,the complicated geometry characteristics of hypoid gears lead to some difficulties in its 3D modeling process,a precise and efficacious model must be accomplished before the above analysis begins.Based on the problems mentioned above,this paper has mainly achieved the following tasks.(1)A new method of modeling the pinion is proposed based on Boolean operation and the 3D Model of the gear set is achieved.Based on the common hypoid gear machiningmethod and the meshing theory of gears,the geometry parameters of gear blanks and the coordinate values of points on gear teeth surface is computed by the MATLAB software,also the 3D model of gears set is accomplished by using the parameters above in Pro/E 3D modeling software.Moreover,a new method of hypoid gear set 3D modeling is proposed based on the geometry feature of the gear and the Boolean operation of 3D modeling software,with this method,a gear set is modeled,too.(2)The kinetic characteristics of hypoid gears as well as the influence factors of engaging force have been researched.A finite element modeling(FEM)is established in the software of Adams and the engaging force is analyzed.The effect of friction,angular velocity and load on engaging force has also been worked out.Moreover,the stress of temporary impact is studied.From the result we can see that the meshing impact intensity increases as the revolving speed grows,while it decreases as the load heightens.The effect of friction is small.(3)The effect of meshing impact on root bending stress and root crack is analyzed.A static finite element contact model of the hypoid gear is developed in ANSYS and the root bending stress is computed.The torque load of the pinion is simulated in Adams for the calculation of bending stress under impact.The effect of meshing impact on root bending stress and root crack is revealed that the meshing impact obviously affects the root bending which can be twice the value of static stress as the revolving speed reaches a certain level.更多还原