| Jujube has good medicinal value and economic value.It has a long history of planting in China,and its varieties are rich and varied.Its planting area and yield are the first in the world.Shihezi University independently developed a dwarf and dense planting jujube harvester,in which the exciting device is the core component.In order to improve the harvesting efficiency of jujube harvester in the field,this paper optimizes the exciting frequency,amplitude and structure of the exciting device.The main conclusions are as follows:(1)With reference to domestic and foreign research literature,it is known that the vibration excitation generation methods of vibrating fruit harvesting machinery at home and abroad mainly consist of two kinds of eccentric rotating mechanism and crank slider mechanism,and the factors affecting of fruit harvesting rate and damage rate during vibration harvesting.The factors mainly include the location of the excitation frequency,amplitude and excitation force on the fruit tree.Meanwhile,in the process,learn and master the classical theoretical model establishment,software simulation analysis and field experiment of the vibrating forest fruit harvesting machine.The method lays the foundation for the research of this thesis.(2)Selecting the jujube planting mode suitable for the operation of dwarf dense planting jujube harvesting machine,and measuring the growth characteristics of jujube trees such as jujube tree height,canopy diameter,trunk height and diameter of three-year,five-year and eight-year-old;Based on the research status at home and abroad,the structure and working principle of the excitation device,and the field investigation results,the parameters and requirements for the optimization of the excitation device are proposed.(3)Three-dimensional modeling software,Solid Works,was used to establish threedimensional models of three-year,five-year and eight-year-old jujube trees.The ANSYS finite element simulation analysis software was used to analyze the modal analysis of the jujube model.The best excitation frequency range of the jujube vibration harvest is 12~18 Hz.A fiveyear-old jujube tree is selected for indoor test verification by electric vibration test rig.The test results are basically consistent with the ANASY simulation analysis results of the jujube threedimensional model.The results obtained from the ANSYS simulation analysis of the jujube model can provide theoretical basis and guidance for the selection of the excitation frequency parameters of the excitation device.(4)According to the structural composition and working principle of the excitation device,the crank-slider excitation mechanism and the jujube vibration system model are established,and the system vibration differential equation is obtained.Combined with the ANSYS simulation analysis conclusion and known reference conditions of the jujube three-dimensional model.The amplitude of the excitation device is 50 mm.The vibration device with improved amplitude is modeled by Solid works of 3D modeling software and imported into the ADAMS software environment for kinematics simulation analysis.The results show that the motion of the excitation device meets the requirements.(5)The structural parameters and frequency parameters of the excitation device are optimized by field trials.Adjust the number of different installation groups and different installation positions of the excitation disc of the excitation device to conduct field trials,record the harvesting rate and damage rate data of jujube,and compare the data between different groups of tests and the different treatments of the same group.Factor analysis of variance,Duncan's difference significance analysis and regression analysis showed that the optimal installation number of the excitation disc was three groups,the best excitation frequency range was 10Hz~15Hz.The jujube harvesting rate of jujube harvesting machine was 86.15%~92.27%,and the jujube injury rate was 2.03%~6.14%. |
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