| Due to the scarcity of wild astragalus resources,and in order to improve the effective components in common astragalus,farmers started the cultivation of organic astragalus.Aiming at the problems of low mechanization level and high labor cost in the process of planting organic astragalus membranaceus,this thesis designed an integrated machine for transplanting astragalus membranaceus and drip irrigation,which can be used in actual production.In order to meet the requirements of structural strength,the static characteristics of the frame were analyzed based on ANSYS.The effect of transplanting mechanism on transplanting rate and missing rate was studied by numerical simulation.The main research contents and conclusions are as follows:(1)On the basis of field research on the planting operation requirements of organic astragalus membranaceus,the overall structure design of the integrated machine of astragalus membranaceus transplanting and drip irrigation was completed.CATIA 3D modeling was used to model the transplanting mechanism,film laying mechanism and drip irrigation mechanism and complete the assembly of the whole machine.The prototype of the integrated machine for astragalus membrane-laying drip irrigation was processed,and the field performance test was carried out.The results showed that the integrated machine could achieve the expected function.(2)The static analysis and modal analysis of the frame were carried out by ANSYS finite element analysis.The results of the static analysis showed that the maximum deformation of the frame was 0.10 mm,the maximum deformation position was located at the seedling platform,and the maximum stress of the frame was 7.38 MPa,which was located at the connection between the plastic film support and the frame of the whole machine.The maximum deformation of the frame under working conditions is 0.85 mm,and the maximum deformation position is located at the connection between the support of the furrow plow and the frame of the whole machine,and the maximum stress is 80.10 MPa,which is located near the film laying mechanism of the seedling carrying platform.The design of the frame under the two working conditions meets the requirements of structural strength.The results of modal analysis show that the external excitation frequency of the frame is less than the first six natural frequencies of the frame,and the resonance damage between the organic astragali and the supporting tractor can be effectively avoided during the planting operation,and the structure design of the frame can meet the requirements of the dynamic characteristics of the whole machine in the working process.(3)The basic physical parameters(geometric size,moisture content,density,Poisson’s ratio,elastic modulus)and contact parameters(collision recovery coefficient,static friction coefficient,rolling friction coefficient)of astragalus were determined by physical test method.The simulation test parameters were selected according to the physical test results,and the Plackett-Burman simulation test was carried out with EDEM.The significance of the simulation parameters affecting the rest-angle was screened.The significant parameters obtained from the test results were the seedling-seedling collision recovery coefficient,seedling-seedling static friction coefficient and seedling-steel plate static friction coefficient.The steepest climbing test was used to determine the optimal value interval of significant parameters.The Box-Behnken simulation test was used to obtain the optimal simulation parameter combination of astragalus as follows: the seedling-seedling collision recovery coefficient was 0.43,the seedling-seedling static friction coefficient was0.42,and the seedling-steel plate static friction coefficient was 0.14.The value of other non-significant parameters is the average value of physical test results.The results of the verification test showed that the relative error between the mean value of astragalus reposition angle measured by the simulation test of 26.46 ° and the physical test of astragalus reposition angle measured by the physical test of 26.83° was 1.06%,and there was no significant difference between the simulation test results and the physical test results.The optimal combination of simulation parameters could be used for discrete element simulation analysis of the performance of the transplanting mechanism.(4)In order to further improve the transplanting operation quality of astragalus membrane-laying drip irrigation integrated machine,the transplanting mechanism was improved.EDEM was used to simulate and analyze the working performance of the improved transplanting mechanism.The single factor and orthogonal simulation experiments were carried out by taking the dip angle of the bottom plate of the seedling feeder box,the rotation speed of the seedling chuck and the rotation speed of the seedling drum as experimental factors,and taking the transplanting rate and the missing rate as evaluation indexes.The results of simulation test proved the influence of working parameters of transplanting mechanism on the process and operation quality of astragalus membranaceus.The orthogonal test results showed that the bottom plate inclination angle of the seedling material box was 113°,the rotation speed of the seedling chuck was 14 rpm,and the rotation speed of the seedling drum was 16 rpm.The transplanting rate reached 95.20%and the missed planting rate was 5.96%,indicating good transplanting quality. |
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