修枝机齿轮箱系统的振动与噪声研究

发布时间：2018-07-24 19:54

【摘要】：修枝机是园林美化工作中的一项重要工具,可以大大提高园林工人对植物的修剪工作。但是传统的设计方法过多考虑修枝机的外形和强度,而忽视其动态特性,使生产出来的产品振动噪声过大,给园林工作者的身体和心理造成了很大的伤害。齿轮箱是修枝机的关键传动部件,其设计制造的不足会造成齿轮箱振动剧烈,从而产生较大的辐射噪声。本文以某型号园林修枝机的齿轮箱系统为研究对象,对其振动特性及由此产生的噪声展开研究,并通过改进结构的措施达到降低齿轮箱系统振动噪声的目的。本文对修枝机齿轮箱系统振动噪声的分析工作如下:(1)修枝机齿轮箱的激励力提取。利用三维软件Solidworks强大的建模功能,建立修枝机齿轮箱的三维CAD模型,进行必要的简化和删减,并且把得到的修枝机齿轮箱传动结构导入ADAMS中。基于多刚体动力学理论,结合修枝机齿轮箱的实际运动情况,设置各零件间的运动约束和接触参数,建立齿轮箱传动系统的多刚体动力学模型。施加驱动,对修枝机齿轮箱的运动过程进行仿真,提取修枝机齿轮箱箱体内两对啮合齿轮的啮合力。(2)修枝机齿轮箱模态分析与实验验证。有限元模型的建立是模态分析的基础,首先,利用Hypermesh对修枝机齿轮箱CAD模型进行前处理;然后,根据齿轮箱的几何特征和大小,采用合适的网格标准,进行网格划分,建立齿轮箱的结构有限元模型。最后再利用ANSYS Workbench对齿轮箱结构的约束模态和自由模态进行计算,约束模态分析得到修枝机齿轮箱实际工作状态下的模态。另外,通过力锤法敲击齿轮箱得到频响函数曲线,基于频响曲线提取试验模态频率。将修枝机齿轮箱的试验自由模态与仿真自由模态进行比较,两者模态频率一致,验证了有限元模型的正确性。(3)修枝机齿轮箱谐响应分析。将前文获取的齿轮箱齿轮啮合力作为激励,加载到修枝机齿轮箱有限元模型上,进行修枝机齿轮箱谐响应分析,得到各个频率下的振动响应,并且通过ANSYS Workbench求得关键参考点X、Y、Z方向的振动位移数据,分析其振动特征。(4)修枝机齿轮箱辐射噪声预测。将修枝机齿轮箱的声学有限元模型导入到LMS Virtual lab中,同时将修枝机齿轮箱的振动结果映射到声学网格上作为辐射噪声分析的边界条件,结合FEM(Finite Element Method)和AML(Automatic Matched Layer)的方法,对修枝机齿轮箱辐射噪声进行预测。(5)修枝机齿轮箱辐射噪声的优化改进。首先介绍噪声对人类的危害,然后根据仿真结果确定在齿轮箱下箱体增加对称加强筋,对修改后的模型重新进行谐响应分析,并基于ATV(Acoustic Transfer Vector)和MATV(Model Acoustic Transfer Vector)理论,运用FEM和AML的方法预测箱体结构优化后的辐射噪声,降噪效果比较明显。
[Abstract]:Pruning machine is an important tool in landscaping, which can greatly improve the pruning of plants by garden workers. But the traditional design method considers the shape and strength of the pruning machine too much, but neglects its dynamic characteristic, which makes the product vibration and noise too big, and causes great harm to the body and psychology of the garden workers. The gearbox is the key transmission part of the pruning machine. The deficiency of its design and manufacture will cause the gearbox to vibrate violently, thus produce the bigger radiation noise. In this paper, the gearbox system of a garden pruning machine is taken as the research object, the vibration characteristics and the resulting noise are studied, and the purpose of reducing the vibration noise of the gearbox system is achieved by improving the structure of the gearbox system. The analysis of vibration and noise of pruning machine gearbox system is as follows: (1) excitatory force extraction of pruning machine gearbox. Using the powerful modeling function of 3D software Solidworks, the 3D CAD model of pruning machine gearbox is established, and the necessary simplification and deletion are carried out, and the obtained gearbox transmission structure of pruning machine is imported into ADAMS. Based on the theory of multi-rigid body dynamics and the actual motion of gear box of pruning machine, the dynamic model of multi-rigid body of gear box transmission system is established by setting up the motion constraints and contact parameters among the parts. The motion process of the gear box of the pruning machine is simulated and the meshing force of two pairs of meshing gears in the gear box of the pruning machine is extracted. (2) Modal analysis and experimental verification of the gear box of the pruning machine. The establishment of finite element model is the basis of modal analysis. Firstly, the CAD model of pruning machine gearbox is pre-processed by Hypermesh, then, according to the geometric characteristics and size of gearbox, the mesh is divided according to the appropriate mesh standard. The finite element model of gearbox structure is established. Finally, the constrained mode and the free mode of the gearbox structure are calculated by ANSYS Workbench, and the modal of the gearbox of the pruning machine under the actual working condition is obtained by the constrained modal analysis. In addition, the frequency response function curve is obtained by tapping the gearbox with the force hammer method, and the test mode frequency is extracted based on the frequency response curve. The experimental free mode of pruning machine gearbox is compared with the simulated free mode, and the modal frequency is the same, which verifies the correctness of the finite element model. (3) Harmonic response analysis of pruning machine gear box. The gearbox gear meshing force obtained in the previous paper is taken as the excitation, and loaded into the finite element model of the pruning machine gearbox, and the harmonic response of the pruning gear box is analyzed, and the vibration response at various frequencies is obtained. The vibration displacement data of the key reference point XNY Z are obtained by ANSYS Workbench, and the vibration characteristics are analyzed. (4) noise prediction of pruning machine gearbox. The acoustic finite element model of pruning machine gearbox is introduced into LMS Virtual lab, and the vibration results of pruning machine gearbox are mapped to acoustic mesh as boundary conditions for the analysis of radiated noise. The method of FEM (Finite Element Method) and AML (Automatic Matched Layer) is combined. The radiated noise of pruning machine gearbox is predicted. (5) the optimization improvement of pruning machine gearbox radiation noise. Firstly, the harm of noise to human being is introduced, and then according to the simulation results, the symmetrical stiffeners are added to the box body under the gearbox, the harmonic response of the modified model is analyzed again, and based on the theory of ATV (Acoustic Transfer Vector) and MATV (Model Acoustic Transfer Vector), the harmonic response of the modified model is analyzed again. The method of FEM and AML is used to predict the radiation noise after the optimization of the box structure, and the noise reduction effect is obvious.
【学位授予单位】：中北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU986.32

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