The Design And Research Of The Cutter-type Orchard Branch Crushing Device

In view of the fact that it is difficult to deal with and utilize a large number of pruning branches in orchards in Xinjiang,and that there are few branch crushers suitable for orchards in Xinjiang,the branches are not completely crushed,and the labor intensity of manual picking and collecting branches is high.In this thesis,the orchard branches are selected as the research object.On the basis of exploring their organizational structure and shear mechanical properties,a rolling cutter type orchard branch crushing device is developed,and the structure of the crushing device is optimized by simulation software.The field experiment is carried out to further determine the optimal structure and working parameters of the branch crushing device.This study is conducive to improving the level of orchard mechanization and solving the problem of orchard biomass resource reuse.The main work and conclusions of this thesis are as follows:1.Study on the material characteristics of fruit tree branches.By studying and analyzing the hardness characteristics of grape,peach,pear,jujube,and apple branches of five kinds of Xinjiang characteristic forest and fruit crops,it is obtained that the hardness of the end surface of the five orchard branches is ranked from largest to smallest: jujube tree > apple tree > pear tree > peach tree > grape.The average hardness of the end face of jujube branch is the largest,and the maximum value is 7200.45 N.Therefore,jujube branches were selected as the research object of this study.The microstructure characteristics of jujube branches were observed by scanning electron microscopy.The results showed that the microstructure of jujube branches was composed of epidermis,phloem,cambium,xylem(catheter,wood ray,wood fiber)from outside to inside.The cross-sectional area of xylem was between 72 % and 77 %,that of phloem was between 15 % and 20 %,and that of pulp was between 4 % and 7 %.Combined with the microstructure of jujube branches and the force-displacement curve of shear test,it was found that the peak shear force occurred at the shear stage of xylem,which affected the visibility : the descending order of blade edge angle,shear angle and loading speed,the shear strength of branches increased with the increase of blade edge angle,and decreased with the increase of shear angle;through comprehensive consideration and optimal shear strength combination,the blade edge angle is 35° and the cutting angle is40°.2.Design the roller type orchard branch crushing device.Combined with the mechanical properties of jujube branches and the planting mode of orchard,the overall scheme of the cutter-type orchard branch crushing device was determined,the working process and principle of the cutter-type crushing device were expounded,and a cutter-type orchard branch crushing device was designed.The branch picking method of picking claws and combing teeth into the ground was used to determine the structural parameters of the key components of the whole machine.The speed of pickup shaft is 200 r / min,and the maximum rotation of pickup claw is 215 mm.The flat blade is selected for crushing hob.The blade angle is 35°,the thickness is 8 mm,and the blade width is 90 mm.The diameter of crushing hob is designed to be 390 mm,and the length is 990 mm.3.Simulation and structure optimization of crushing device.The sixth-order modal analysis of the crushing shaft was carried out by finite element software.The results show that the design of the crushing shaft meets the structural requirements of the device.The lightweight optimization design of the tool holder is carried out,and the weight of the crushing single tool holder is reduced by 73 %.The transient analysis verifies that the allowable stress of the material is greater than the transient impact force of the tool holder,which meets the design requirements.According to the jujube branches and mechanical properties,the discrete element simulation particle model of jujube branches was established.The discrete element method was used to simulate and analyze the crushing process of jujube branches,optimize the arrangement of hob cutters,and determine the arrangement of segmented dislocation double helix blades.4.The device was trial-produced and field experiments were conducted.A hob-type orchard branch crushing device was trial-produced,and a quadratic polynomial model of each factor affecting the two indexes was established by taking the branch recovery rate and the qualified rate of crushing length as the indexes,and the four-factor and three-level experiments were carried out with the factors of the soil depth of picking comb teeth,the rotational speed of crushing shaft,the rotational speed of feeding shaft and the clearance of stationary knife as the factors.The analysis of the two models shows that the order of the obvious aboriginality of the branch recovery rate from large to small is the soil depth of picking comb teeth,the rotational speed of feeding shaft,the rotational speed of crushing shaft and the spacing of stationary knife,and the order of the obvious aboriginality of the qualified rate of crushing length from large to small is the rotational speed of crushing shaft,the spacing of stationary knife,the rotational speed of feeding shaft and the soil depth of picking comb teeth.The regression data equation with the target of the recovery rate of branches and the qualified rate of crushing length was established;according to the model data,the optimal parameters of the device are determined by multi-factor parameter optimization : the rotational speed of the crushing shaft is 1400 r / min,the rotational speed of the feeding shaft is 350 r / min,the clearance of the fixed knife is 14 mm,and the depth of picking up the comb tooth into the soil is 31 mm.The verification test was carried out.The final test results showed that the branch recovery rate was91.57 %,and the qualified rate of crushing length was 90.19 %,which proved the feasibility of the test device and met the design requirements.