环模制粒机齿轮减速器动力学特性分析

环模制粒机的内部激励会引起整机振动,振动是导致环模与压辊使用寿命降低的主要原因。该研究针对环模制粒机振动大、关键部件使用寿命短等问题,以SZLH420型环模制粒机减速器为研究对象进行动力学分析与试验。首先基于累积势能法计算齿轮时变啮合刚度,建立斜齿轮传动动力学模型,采用解析法对传动系统进行模态分析和非线性动力学求解,求得最大振幅Y向(水平径向)为0.008 mm、Z向(轴向)为0.004 2 mm、转角为0.000 87°,并通过有限元仿真验证动力学模型和固有频率。最后进行主轴扭矩测试与斜齿轮振动加速度试验。结果表明,整机振动加速度频率与斜齿轮一致,故斜齿轮传动系统对整机振动具有重要影响,其主要振动频率在4.25、9.17、13.86、18.13、23.86、47.53 Hz附近;齿轮振动最大幅值Y向为0.006 mm、Z向为0.004 mm,与动态响应计算对应振幅最大差值不超0.002mm,验证了理论计算的准确性。研究结果可为环模制粒机性能的提高提供理论与试验依据。

Dynamic characteristics analysis of the gear reducer of ring mold granulators

Abstract: Serious vibration in most mechanical equipment has posed a great impact on the production efficiency of agriculture goods and the service life of key parts. Much efforts have been made on the influence of external excitation on the vibration generation, transmission, and even reduction at present. However, there are only a few studies on the influence of internal excitation on the vibration in the ring mold granulator, such as the ring mold and pressing roller. Taking the gear reducer of 420 ring mold granulator as the research object, this study aims to analyze the dynamic characteristics on the complex transmission, large vibration, and short service life of key parts. The time-varying meshing stiffness and meshing error of helical gears were attributed to the internal excitation of transmission system. A cumulative integral potential energy was used to calculate the time-varying meshing stiffness of gear reducer in a ring mold granulator, thereby to determine the variation of meshing stiffness. Then, a six degree of freedom (DOF) dynamic model was established to determine some parameters for the helical gear transmission system in a ring mold granulator. Since the dynamic response clearly reflected the gear vibration, a modal analysis of transmission was made to effectively avoid the nonlinear dynamic resonance. At the same time, a systematic evaluation was carried out to explore the effects of meshing stiffness and comprehensive meshing error on the dynamic response of helical gear transmission. More importantly, the obtained meshing stiffness of helical gear was utilized to optimize the dynamic response of system for a higher installation accuracy in regular maintenance. Furthermore, a finite element (FE) software was used to verify the accuracy of natural frequency in the dynamic model. A spindle torque test of granulator was also carried out to measure the torque time-domain curve. Fourier transform (FT) was then utilized to transformed into the power spectrum curve. A spectrum analysis demonstrated that there was no resonance of main motor with the transmission system, although the complex internal excitation of a granulator from the torque fluctuation. Additionally, an acceleration vibration test was performed on the whole machine and helical gear transmission. The curve of vibration time domain was measured to transform into the vibration frequency domain. The vibration characteristics of helical gear transmission were analyzed to verify the internal excitation in the whole granulator. Finally, the curve of vibration time-domain was integrated to obtain the displacement fluctuation. The test and theoretical calculation of dynamic response indicated that the internal excitation was an important reason for the vibration of whole machine.