谷物联合收获打捆复式作业机振动分析与压缩装置结构优化

发布时间：2018-03-05 10:26

本文选题：收获打捆复式作业机　切入点：振动测试　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：我国农作物秸秆年产量近7亿吨,但秸秆的综合利用率只有33%。通常在田间对秸秆进行焚烧处理,而秸秆燃烧产生的烟雾会长期留在空气中,严重影响空气质量,所以提高秸秆的综合利用率迫在眉睫。本文根据现有沃得DC50C轮式联合收割机结构特点,设计了一种谷物联合收获打捆复式作业机,该机突破了传统收割机和打捆装置的简单对接方式,具有田间通过性好,转弯半径小等优点。此外,由于该复式作业机结构复杂,工作部件和传动部件较多,在恶劣环境下工作时,整机振动和噪音非常明显,而压缩装置作为该复式作业机核心工作部件,当其固有频率与整机各激振源频率临近时,易出现整机共振现象,影响整机可靠性和驾驶员舒适性,因此,研究谷物联合收获打捆复式作业机整机及压缩装置的振动特性尤为必要。本文主要研究内容如下:(1)对复式作业机整体结构和工作原理进行阐述与分析,对整机配置、传动系统、喂入装置和压缩装置等关键部件进行结构设计及参数计算,联合收获机与打捆装置间采用三级减速传动装置,喂入装置采用曲柄连杆拨叉机构,压缩装置采用对心式曲柄滑块机构,喂入装置和压缩装置工作频率设计为93r/min,对曲柄连杆拨叉机构进行运动学仿真,拨叉末端运动轨迹显示秸秆能够顺畅输送,该复式作业机相比与传统的牵引式打捆机,转弯半径更小,田间通过性更好。(2)对复式作业机整机7个测点的振动水平进行测试,获取其时域信号和频域信号的变化规律,重点对压缩装置进行振动特性分析,振动试验结果表明压缩装置存在共振的内在可能。因此,对压缩装置进行模态分析,通过有限元仿真得到压缩装置的前6阶模态频率及对应振型,结果表明压缩装置一阶固有频率与振动筛激振频率相临近,压缩装置三阶、四阶固有频率与发动机激振频率相临近。(3)利用PCB激振力锤、加速度传感器、动态信号采集仪、模态分析系统对复式作业机压缩装置进行试验模态分析,通过参数识别与信号分析得到压缩装置的前6阶模态参数,并与有限元计算结果对比分析,验证了压缩装置有限元仿真的准确性。最后以压缩装置有限元模型为基础,以改变压缩装置固有频率为目标进行结构优化,并对优化后的模型进行有限元验证,优化结果表明:优化后压缩装置的固有频率避开了各激振频率,验证了优化方案的可行性。(4)对复式作业机进行田间性能试验,试验结果表明:以规则草捆率为评价指标,下喂入装置可高效完成秸秆输送,压缩装置压缩效果好。草捆成捆率、规则草捆率、抗捆率、草捆密度、草捆截面尺寸、纯工作小时生产率均达到设计要求,整机样机作业协调性好,结构设计与参数选择合理,整机性能指标均能够达到生产需要。
[Abstract]:The annual yield of crop straw in China is nearly 700 million tons, but the comprehensive utilization ratio of straw is only 33. The straw is usually incinerated in the field, and the smoke produced by straw burning will stay in the air for a long time, which will seriously affect the air quality. Therefore, it is urgent to improve the comprehensive utilization ratio of straw. According to the structural characteristics of the existing DC50C wheeled combine harvester, this paper designs a kind of combined grain harvesting and bundling machine. This machine breaks through the simple docking mode of traditional harvester and baling device, and has the advantages of good field passing ability and small turning radius. In addition, because of the complex structure of the duplex machine, there are many working parts and transmission parts. When working in bad environment, the vibration and noise of the whole machine are very obvious. As the core working part of the duplex machine, when the natural frequency of the compressor is near to the frequency of the exciting source of the whole machine, it is easy to appear the whole machine resonance phenomenon. Affect the reliability of the whole machine and driver comfort, therefore, It is particularly necessary to study the vibration characteristics of the whole machine and the compression device of the combined harvest and bundling machine. The main contents of this paper are as follows: 1) the whole structure and working principle of the compound machine are expounded and analyzed, and the whole machine configuration and transmission system are described and analyzed. The structure design and parameter calculation of key parts such as feeding device and compression device are carried out. A three-stage deceleration drive is used between the combine harvester and the binding device, and the feeding device adopts a crank and connecting rod fork mechanism. The compression device adopts the countercore crank slider mechanism. The working frequency of the feeding device and the compression device is 93 r / min. The kinematics simulation of the crank and connecting rod fork mechanism shows that the straw can be transported smoothly. Compared with the traditional traction strapping machine, the compound machine has smaller turning radius and better field pass. The vibration level of 7 measuring points of the duplex machine is tested, and the variation law of its time-domain and frequency-domain signals is obtained. The vibration characteristics of the compression device are analyzed, and the results of vibration test show that there is inherent possibility of resonance in the compression device. Therefore, the modal analysis of the compression device is carried out. Through finite element simulation, the first 6 modes and corresponding modes of the compression device are obtained. The results show that the first natural frequency of the compression device is close to the exciting frequency of the vibrating screen, and the third order of the compression device is obtained. The fourth order natural frequency is near to the engine exciting frequency.) using the PCB exciting force hammer, acceleration sensor, dynamic signal collector and modal analysis system, the test modal analysis is carried out on the compression device of the compound operation machine. Through parameter identification and signal analysis, the first 6 modal parameters of the compression device are obtained, and compared with the finite element calculation results, the accuracy of the finite element simulation of the compression device is verified. Finally, the finite element model of the compression device is used as the foundation. The structure optimization is carried out with the aim of changing the natural frequency of the compression device, and the optimized model is verified by finite element method. The optimization results show that the natural frequency of the optimized compression device avoids all the exciting frequencies. The feasibility of the optimized scheme was verified. 4) the field performance test of the duplex machine was carried out. The results showed that with the regular straw bundle rate as the evaluation index, the feeding device could efficiently complete the straw conveyance, and the compression device had a good compression effect. The regular Bale rate, Bale Resistance rate, Bale density, Bale Cross Section size, working hour Productivity are all up to the design requirements, the whole prototype has good coordination, reasonable structure design and parameter selection, and the performance index of the whole machine can meet the production requirements.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S225.3

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