拔秆粉碎机粉碎装置优化及液压系统设计

【作者】 杨康；

【导师】 赵丽梅；

【作者基本信息】 贵州大学 ， 机械工程， 2018， 硕士

【摘要】 烟秆是烟叶采摘后的特殊副产物,目前我国烟草种植业机械化回收水平较低,主要由人工进行拔秆,费时费力,且现有的拔秆装备不能够进行拔秆粉碎一体化作业,生产效率较低。本课题研制的拔秆粉碎机,可以一次性完成拔秆、输送、清理和粉碎作业,提高烟秆拔秆、回收以及粉碎的生产效率。本文的主要研究内容为移动式拔秆粉碎机的喂料装置设计、粉碎机刀片和粉碎室的优化、液压系统的设计以及样机田间实验。为了有效防止粉碎室内的负压将烟秆过快吸入粉碎机中导致粉碎效果差,设计了粉碎机的喂料装置来控制烟秆的喂入速度;为了保证粉碎质量,设计了喂料试验装置并进行虚拟装配与运动仿真,加工实现喂料试验装置,并试验研究了粉碎质量与喂料速度的关系。为了解决粉碎机的切割功耗和震动幅度大、切割时受力不均等问题,首先,采用对数螺线方程设计了粉碎机切割刀片的等滑切角刀刃曲线,然后,为获得低能耗的刀刃曲线,通过对烟秆秸秆质点的运动学分析建立了切割烟秆的功耗模型,提出了基于能耗模型的等滑切角刀片优化设计方法并得到了理论最优的滑切角,最后,通过对比切割试验验证了优化效果。为提高粉碎机的粉碎效率,改善粉碎质量,采用ANSYS Fluent软件,使用多重参考坐标模型(MRF)和k-ε湍流模型对粉碎室流场进行仿真。得到了原有粉碎机粉碎室的压力图,速度矢量图,气流迹线图。根据粉碎室流场的分析结果,提出粉碎机粉碎室排料口位置和粉碎室结构的优化方案,优化后的粉碎机粉碎室内的环流现象减弱,排料口的排料情况也有所改善。为了将流量合理地分配到拔秆粉碎机的各执行机构,提出了在单泵多马达液压系统的支路上安装电液比例调速阀的流量分配方法,采用AMESim软件建立流量分配系统的仿真模型,并对该流量分配方案的流量分配和抗饱和能力进行了仿真研究。基于提出的流量分配方法,设计实现了拔秆粉碎机液压系统。为了验证拔秆粉碎机设计方案的可行性并考察其工作性能,进行了田间试验。研究了不同输送马达转速下的粉碎质量并确定了最佳转速,匹配了拔杆马达和输送马达的转速,验证了液压系统的设计方案的可行性并对整机的工作性能进行了研究。更多还原

【Abstract】 Tobacco stalk is a special by-product of tobacco leaves after being harvested.At present,the technology level of mechanized recovery in tobacco planting industry in China is relatively backward,as most of tobacco stalk pulling are carried out by manpower,which consumes too much time and labor.As the existing stalk pulling equipment cannot integrate pulling with shredding stalks at a time,which makes the low production efficiency.Movable tobacco stalk pulling and shredding machine developed in this subject integrates functions of stalk pulling,cleaning,stalk conveying,and shredding,all of them can be finished at one time,Thus,it can improve the production efficiency of tobacco stalks from three processes respectively,stalk pulling,recovery and shredding.The main contents of this paper are as follows: designing a feeding device for the movable tobacco stalk pulling and shredding machine,optimizing the shredder’s cutting blade,improving the performance of the shredder’s chamber,as well as the design of the hydraulic system and the trials of the prototype in the field.In case of appearing that the stalks being sucked into the shredder’s chamber too quickly which results in poor shredding quality because of too much negative pressure in the crushing chamber.A feeding device of the shredder is designed to control the feeding speed of the tobacco stalks;To ensure the shredding quality,a feeding test device is designed,virtual assembly and the movement simulation is also carried out.After that,the feeding device for trial is produced and it is used to study on the relationship between the shredding quality and feeding speed by trails.To reduce the cutting power consumption and solve the problems of vibration,unbalanced force during cutting,according to the Gaolveqijin Theorem,an optimized design method of equal sliding-cutting angle blade which is based on energy consumption model is proposed.Firstly,the equal sliding-cutting curve of the cutting blade of the shredder is designed using the logarithmic spiral equation.Then,in order to obtain the blade curve with a low energy consumption,a power consumption model of cutting tobacco stalks based on the kinematics analysis of the straw stalk mass point is established and then the theoretical optimal sliding-cutting blade angle is obtained.Finally,a comparative cutting test is performed on the cutting edges with different sliding-cutting angles to verify the practical working effect of the designed equal sliding-cutting angle cutting edge with τ=48°.In order to distribute the flow to the actuators of the stalk pulling and shredding machine reasonably,a flow distribution method of installing the electro-hydraulic proportional speed regulating valve on the branch of the single-pump and multi-motor hydraulic system is proposed.The flow distribution simulation model of the hydraulic system is established using AMESim software,and the simulation analysis of the flow distribution and anti-saturation capability of the hydraulic system is conducted with the software.Based on the proposed flow distribution method,a hydraulic system for movable tobacco stalk pulling and shredding machine is designed and produced.Finally,for verifying the feasibility and performance of the design for the movable stalk pulling and shredding machine,the field trials are conducted.Through trials,the shredding quality at different conveying motor speeds is studied and the optimal rotation speed is also determined,the rotation speeds of the pulling motor and the conveying motor also get matched.The design scheme of the hydraulic system and the performance of the whole machine are verified in the end.更多还原