| Jujube industry is a characteristic and dominant industry in Xinjiang,and pruning is the key to improve the quality and increase production of jujube trees.Every year,up to 2 million tons of jujube branches are produced due to pruning.A huge amount of jujube branches can only be treated by accumulation and burning in gullies,which has great safety risks and is not sustainable.The function of the branch crushing and returning to the field developed by the research group in the early stage basically meets the needs of farmers,but there are still some prominent problems,such as insufficient pulverizing size and large pulverizing power.Therefore,based on the organizational structure and mechanical characteristics of jujube pruning branches in dwarf and dense planting jujube orchard,this paper designed the crushing device of jujube cutting and returning machine for dense planting jujube orchard through mechanical analysis and virtual simulation technology and completed the trial production.Through the design of related tests,the correlation and influence rule between the structural parameters and working parameters of the device and the crushing performance were analyzed,and the parameter optimization was completed,which improved the crushing performance of the jujube branch crushing device.The research was conducive to promoting the healthy and rapid large-scale development of the jujube industry in XinjiangThe main work of this paper is as follows:1.Study the material characteristics of jujube branches.Using related instruments and tools to determine the organizational structure,mechanical properties,dimensions,physical properties of jujube pruning branches.The results showed that jujube pruned branches had higher lignin content and hardness,which were different from straw materials.Densely planted jujube garden jujube tree pruning branches of its thickest diameter in 35mm or less;The sampling position and distance span of jujube branches have significant influence on the maximum bending force,and the maximum bending force is less than the maximum compression force.The transverse compression force is less than the longitudinal compression force;The density of jujube branches was 875kg/m~3;The impact recovery coefficient of jujube was 0.42.The impact recovery coefficient between jujube branches and steel is 0.45.The static friction coefficient between jujube branches was 0.91.The static friction coefficient between jujube branches and steel is 0.65.The rolling friction coefficient between jujube branches was 0.10.The rolling friction coefficient between jujube branches and steel is 0.125.These conclusions provide data support for device design and discrete element modeling.2.Design of crushing device.According to the results of the material test,the overall design scheme of the crushing device was formulated,the overall structure of the device was determined,the relevant theoretical analysis was carried out,and the structural parameters of the rotor assembly,the crushing sieve plate and other key components were determined.Through ANSYS software,modal analysis and static analysis were carried out on the key parts of the spindle and the sieve plate,and the structural strength of the device was preliminarily verified,and the design of the crushing device was completed.3.Simulation analysis of branch crushing process based on discrete element method.According to the parameters measured in the test,the contact parameters were selected and calibrated through a series of tests with the stacking Angle as the evaluation index.The bond parameters were calculated according to relevant formulas,and the bond parameters were selected and demarcated through bending tests.The discrete element Bond bond model of jujube pruning branches was established.The simulation model of jujube branch-pulverizing device was established,and the pulverizing process of jujube pruning branches in the pulverizing device was simulated and analyzed by using EDEM software.It was found that impact pulverizing,impact pulverizing and rubbing pulverizing occupied the main position in the pulverizing process of jujube branches.The main factors affecting the comminution performance are the structure of the sieve plate and the rotation speed of the cutter shaft,etc.These conclusions provide a support for the subsequent experimental research.4.Crushing device test.Processing manufacture crushing device,crushing length percent of pass,the average power as evaluation index,in the form of structure parameters of the mesh shape,the structure of the washboard,washboard arrangement form,the working parameters of speed,feed rate as test factors,according to the experiment aim combination parameter feature design and implementation of the orthogonal experiment,response surface test,It is concluded that the mesh shape has a significant effect on the pass rate of the grinding length,but not on the average power.The structure of washboard has a significant effect on the qualified rate of crushing length.It has no significant effect on the average power.The washboard arrangement has a significant effect on the qualified rate of the crushing length and the average power,and the optimal combination of structural parameters is the elliptical sieve,cylindrical washboard and inverted ladder washboard arrangement.The results show that,within the level range of design factors,the speed and feeding amount have significant effects on the qualified rate of the grinding length,the speed has significant effects on the average power,and the feeding amount has no significant effects on the average power.It is concluded that the optimal combination of working parameters is the feeding amount of 2.0kg and the grinding cutter shaft speed of 1973 r/min.Through verification test,it can be concluded that under the above optimal combination parameters,the qualified rate of the grinding length of the device can reach 91.23%,and the average grinding power can reach 4.72kW,which can meet the design requirements. |
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