油菜联合收割机割台模态分析及试验优化

Modal analysis and experimental optimization of the header of rape combine harvester

【目的】目前我国大部分的油菜联合收割机都是在水稻收割机割台驳接油菜割台的基础上改进而来,分析油菜联合收割机割台整体结构力学和振动特性并对其进行结构优化,有利于提高油菜收获效率.【方法】运用Workbench对油菜割台优化前、优化后分别进行有限元分析(静力学、模态分析),并使用CoCo-80动态信号分析仪与三轴加速度传感器进行田间振动试验.【结果】优化前第一阶模态频率为7.867 Hz,最大等效应力、变形量分别为92.587 MPa、8.344 mm,田间振动试验中第一阶模态频率为6.25 Hz,发动机激振频率的倍频对割台影响较大,优化后割台第一阶模态频率为11.555 Hz,且最大等效应力、变形量分别降低了14.775%,60.854%,有效的避开了割刀、链把式输送器的主动轮以及脱粒滚筒激励频率的激振范围,减缓了割台振动.【结论】文中提出的优化方法使得割台可满足强度和振动稳定性要求,为油菜割台优化改进提供了理论指导.

【Objective】At present,most of the rapeseed combine harvesters in China are improved on the basis of the rice harvester headers and the rapeseed headers,it is beneficial to improve the harvesting efficiency of rapeseed by analyzing the overall structural mechanics and vibration characteristics of the rapeseed combine harvester headers and optimizing its structural.【Method】The Workbench in the Finite Element Analysis was applied to the header(statics and modal analysis)before and after optimization of the rape header,and the vibration test was carried out in the field using CoCo-80 dynamic signal analyzer and three-axis acceleration sensor.【Result】Before optimization,the first-order modal frequency was 7.867 Hz,the maximum equivalent stress and deformation were 92.587 MPa and 8.344 mm,respectively.The first-order modal frequency was 6.25 Hz in the vibration test in the field,and the multiplication frequency of the engine excitation frequency had a greater influence on the header.After optimization,the first-order modal frequency of the header is 11.555 Hz,and the maximum equivalent stress and deformation are reduced by 14.775%and 60.854%,respectively,which effectively avoids the excitation range of the cutter wheel,the chain of the chain conveyor and the excitation frequency of the barrel,which also slows the vibration of the header.【Conclusion】The optimized header meets the requirement of strength and vibration stability,which provides theoretical guidance for the optimization of rapeseed headers.