联合收获机清选筛箱轻量化设计与试验

Lightweight Design and Test of Cleaning Sieve for Combine Harvester

摘要:

清选筛箱通过往复运动对脱粒后的混合物进行筛分，是组成联合收获机的核心部件之一。针对谷物联合收获机清选筛箱存在整体质量偏重、强度富余的问题进行轻量化设计。基于清选筛箱动力学分析，分析在工作状态下清选筛箱固有频率和结构强度，确定了最大等效应力位置及主要应力分布区域。基于等效静态法将动态响应转化为静态响应，以柔顺度最小为优化目标，以结构强度和质量响应约束条件对清选筛箱侧壁进行拓扑优化。采用尼龙作为轻质材料对抖动板结构进行设计，以拓扑优化结果为基础，提取主要结构特征进行模型重构和动力学分析。结果显示，优化后清选筛箱前6阶固有频率变化最大为1.68Hz，最大等效应力由56.59MPa下降至52.46MPa，降幅为7.29%，质量由75kg降至66.85kg，降低10.86%。在此基础上，利用优化后的清选筛箱搭建了试验台架，开展实际工况下的应变试验和耐久性试验，试验结果验证了优化后的清选筛箱满足实际工作强度、刚度要求，有效提高了清选筛箱的工作性能。

Abstract:

The cleaning sieve is one of the core components of the combine harvester, which screens the threshed mixture through reciprocating motion. Focusing on the lightweight design of the cleaning sieve of the grain combine harvester, which has the problems of overall weight bias and excess strength, based on the dynamics analysis of the cleaning sieve, the natural frequency and structural strength of the cleaning sieve in working condition were analyzed by using the equivalent static method. The maximum equivalent stress position and main stress distribution area were determined. The dynamic response was transformed into static response by using the equivalent static method. By minimizing the compliance and subject to constraints of structural strength and mass response, the topological optimization of the side wall of the cleaning sieve was conducted. Finally, nylon was chosen as a lightweight material for the design of the jitter plate structure. Based on the results of topological optimization, the main structural features were extracted for model reconstruction and dynamic analysis. The results showed that the maximum variation of the first six natural frequencies of the optimized sieve box was 1.68Hz, and the maximum equivalent stress was decreased from 56.59MPa to 52.46MPa, resulting in a reduction of 7.29%. The mass also was decreased from 75kg to 66.85kg, representing a reduction of 10.86%. Based on these results, an experimental platform was built by using the optimized sieve box, and strain tests and durability tests were conducted under actual working conditions. The test results verified that the optimized cleaning sieve met the strength and stiffness requirements for actual operation, effectively improving the working performance of the cleaning sieve.