Finite Element Analysis of Failure Mechanism of Sugarcane Harvester Transfer Case Transmission Shaft

分动箱在运行一段时间后,出现了轴承内圈被压坏、轴承滚珠脱落、传动轴键槽崩裂失效等现象。针对现有的甘蔗收获机分动箱传动轴存在的问题,本文以失效最严重的砍蔗剥叶齿轮的动力输出轴为研究对象,对其进行有限元分析。有限元静力学分析结果表明动力输出轴在强度和刚度上满足生产要求;结合虚拟样机技术,仿真分动箱齿轮在平行不同轴情况下的动载荷曲线啮合情况,获得动力输出轴的动载荷曲线,进而加载在动力输出轴上进行有限元瞬态动力学分析,分析结果表明最大应力集中值出现在小轴颈端的键槽处,超出了材料的许用范围,必然造成传动轴的失效。甘蔗收获机分动箱传动轴的有限元分析结果揭示了传动轴失效的原因。Transfer case after operation for a period of time, the bearing inner ring is shedding crushing, ball bearing, the drive shaft keyway cracking failure phenomenon. In view of the problems existed in the axle of existing sugarcane harvester transfer gear transmission. In this paper, the failure of the worst cutting sugarcane peeling leaf gear of the power output shaft as the research object, the for finite element analysis. Finite element static analysis results show that the power output shaft in strength and stiffness to meet the need of production, combined with the virtual prototype technology, simulation transfer case gear in different parallel axis of dynamic load curve mesh, the power output shaft of dynamic load curve and loading on the power output shaft were finite element transient dynamic analysis. Analysis results show that the maximum stress focus appears at the end of the neck of a small shaft keyway place, beyond the material allowable range. As a result, the transmission shaft failure. Sugarcane harvester transmission shaft of the transfer case of finite element analysis results reveal the causes of shaft failure.国家自然科学基金资助项目(E050303);广西制造系统与先进制造技术重点实验室开放课题(11-031-12S04

Analysis and improvement of transportation performance of sugarcane cutter spiral lifting mechanism

为改善甘蔗收割机物流系统的堵塞问题,以切割器螺旋提升机构为主要研究对象,通过仿真模拟分析与试验研究手段,探讨了摩擦系数等因素对甘蔗物流堵塞的影响,通过UG和ADAMS建立虚拟样机仿真模型,仿真结果表明,增大螺旋的摩擦系数可以提高甘蔗的输送速度,减少甘蔗平均滞留时间。高速摄影试验表明,螺旋选用摩擦系数大的轮胎胶作为覆盖层时、当切割器转速在750 r/min左右时,甘蔗的滞留时间较原钢筋螺旋缩短了17%左右,可以改进切割器物流系统堵塞问题。基于上述机理,设计了平面螺旋结构,其与甘蔗的接触方式由原来的点接触变为线接触,仿真分析表明,面宽为20 mm的螺旋与原圆柱型螺旋相比,甘蔗滞留时间缩短了32%,说明平面螺旋可以有效地抑制前端输送系统的堵塞现象;适当加宽螺旋提升机构的面宽有利于减少甘蔗滞留时间,单位时间内甘蔗输送更快、更稳定。该研究为后续试验研究及物理样机的改进设计提供了参考。 In order to improve the blocking issue of logistics system in sugarcane harvester, by the methods of simulation analysis and experimental research, the cutter spiral lifting mechanism and the effects of friction coefficient and working parameters on the sugarcane material flow were studied and discussed. The average residence time of sugarcane in the transmission device of the screw conveyor was considered as test index and the virtual prototype simulation model was established by the software ADAMS and Unigraphics. Simulation results indicated that increasing friction coefficient of cutter spiral lifting mechanism could improve the delivery rate of the sugarcane and effectively inhibit the clogging problem. The high-speed photography results of experimental prototype showed that while a tyre rubber with high friction coefficient was used as the covering layer for the cutter spiral lifting mechanism and the cutter speed was about 750 r/min, the retention time of sugarcane was shortened by 17% compared to original rebar spiral lifting mechanism. This characteristic could improve the congestion problem of logistics system, and verify that the friction coefficient was exactly the main affecting factor. Based on this principle, this paper worked out the structure improvement of the cutter spiral lifting mechanism. The helical circular cross section was changed into a helical rectangular cross section, which made the contact way of the cutter spiral lifting mechanism and sugarcane change from point contact originally to line contact. The computer simulation experiments under different structures＇ transmission speed, displacement, force and so on were conducted, and the analysis indicated that for the 20 mm cutter spiral lifting mechanism that was improved, the sugarcane residence time was shortened by 32% comparing with the original cylindrical spiral. Meanwhile, after the sugarcane head entered the spirals, the loading time from the spiral to the sugarcane head relatively decreased and the time of the loading proce国家自然科学基金资助项目(51465006

小型甘蔗收获机分动箱性能优化及试验研究

针对小型甘蔗收获机分动箱工作过程中的因受力变形而导致振动过大和工作失效问题,根据分动箱的薄弱环节,提出了分动箱结构改进方案,并对结构改进优化前后的分动箱进行振动测试分析。试验结果表明:振动加速度强度峰峰值同比下降15.4%~32.2%,有效值下降6.5%~30.1%;改进后箱体有效避开了发动机的振动频率,分动箱性能得到了提高,并且得出了分动箱的主要振源,为分动箱的减振处理提供了依据。国家自然科学基金项目(E050303);广西制造系统与先进制造技术重点实验室开放项目(11-031-12S04

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^