小四轮变速箱齿轮的接触分析及修形的研究

发布时间：2018-10-04 23:30

【摘要】：小四轮拖拉机在陕北、甘肃等丘陵地区仍然是应用很普遍的农用动力机械,但是小四轮拖拉机的振动噪声问题依然困扰着人们,变速箱噪声是小四轮拖拉机的主要噪声源之一,而变速箱的噪声源主要来自于齿轮传动。噪声与齿轮传动时的传递误差和啮合刚度有直接的关系,随着操作人员对拖拉机舒适性要求的提高,从而对齿轮传动的减振降噪提出了更高的要求。因此,为了减小齿轮啮合时的振动噪声,并且在不改变齿轮基本参数的前提下,齿轮修形则成为一种极其重要的减小噪声的方法。本文以东方红YTO-180小四轮变速箱齿轮为研究对象,针对其齿轮传动时的承载能力与平稳性问题,对齿轮接触分析进行了研究,探索了齿轮修形对齿轮传动承载能力与平稳性的影响,主要研究的内容及结论如下:首先,利用Pro/E建立参数化齿轮模型,结合齿轮啮合原理实现了齿轮副的无干涉装配。其次,借助ANSYS Workbench,将Pro/E齿轮模型导入有限元软件中,设定符合实际工况的边界条件和约束载荷,对齿轮进行了基本的有限元分析,包括静力学分析、模态分析、瞬时动力学分析,结合分析结果得出了齿轮接触应力应变的变化规律。然后,主要研究了齿廓修形对齿轮传动性能的影响,通过对直线修形的有限元分析可以得出,修形后的最大接触应力值变为2310MPa,修形后的接触压力是726.99MPa。齿廓修形后由于接触区域减小,这样有利于减小轮齿啮合齿数变化时临界点的应力值,避免了啮合齿数变化时引起的冲击现象;另外,最大接触应力值曲线过渡比较平滑,在啮入啮出位置避免了应力集中的问题,对齿轮系统传动平稳性起到了良好的作用,有利于减小振动噪声,延长了齿轮副的使用寿命。最后主要研究了鼓形修形对齿轮传动性能的影响,经过对齿向修形的轮齿进行分析比较,鼓形修形后的最大接触应力值降低了46.36%,减小了啮入啮出应力值偏大的情况,改善了轮齿啮合冲击现象;接触压力降低了20.75%。鼓形齿的齿向修形和齿端修薄可以减小啮入啮出时的最大接触应力值,从而避免在啮合齿数变化时的冲击现象,改善了载荷的分布,提高了传动的稳定性,有利于减小振动噪声。
[Abstract]:Small four-wheeled tractors are still widely used in hilly areas such as northern Shaanxi and Gansu, but the vibration and noise problems of small four-wheeled tractors still plague people. The transmission noise is one of the main noise sources of small four-wheeled tractors. The noise source of the gearbox mainly comes from the gear transmission. The noise is directly related to the transmission error and the meshing stiffness of the gear transmission. With the improvement of the operator's requirement for the tractor comfort, a higher demand is put forward for the vibration and noise reduction of the gear transmission. Therefore, in order to reduce the vibration noise in gear meshing, and without changing the basic parameters of gear, gear modification becomes an extremely important method to reduce noise. This paper takes the Dongfanghong YTO-180 small four-wheel gearbox gear as the research object, aiming at the bearing capacity and smoothness of the gear transmission, the contact analysis of the gear is studied. The influence of gear modification on the bearing capacity and smoothness of gear transmission is explored. The main research contents and conclusions are as follows: firstly, the parameterized gear model is established by using Pro/E, and the non-interference assembly of gear pair is realized by combining with gear meshing principle. Secondly, with the help of ANSYS Workbench, the Pro/E gear model is introduced into the finite element software, and the boundary conditions and constraint loads are set up in accordance with the actual working conditions, and the basic finite element analysis of the gear is carried out, including static analysis, modal analysis and instantaneous dynamic analysis. Combined with the analysis results, the change law of gear contact stress and strain is obtained. Then, the influence of tooth profile modification on gear transmission performance is mainly studied. Through the finite element analysis of straight-line modification, it can be concluded that the maximum contact stress value after modification is 2310 MPA, and the contact pressure after modification is 726.99 MPA. Due to the decrease of contact area after tooth profile modification, it is advantageous to reduce the stress value of the critical point when the tooth number changes, thus avoiding the shock phenomenon caused by the change of tooth number, in addition, the transition of the maximum contact stress curve is smooth. The problem of stress concentration is avoided in the position of gnawing in and out of the gear system, which plays a good role in the smoothness of the transmission of the gear system, and helps to reduce the vibration and noise and prolong the service life of the gear pair. Finally, the influence of drum shape modification on gear transmission performance is mainly studied. Through the analysis and comparison of gear teeth with tooth profile modification, the maximum contact stress value of drum shape modification is reduced by 46.36 and the large value of Erosion-out stress is reduced. The gear tooth meshing impact is improved and the contact pressure is reduced by 20.75. The tooth orientation modification and tooth end trimming of the drum tooth can reduce the maximum contact stress when the tooth is gnawed out, thus avoiding the impact phenomenon when the meshing tooth number changes, improving the distribution of the load and increasing the stability of the transmission. It is advantageous to reduce vibration and noise.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH132.41;S219

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