Design And Experiment Of Key Components For Twin Screw Propelled Lotus Root Digger

In response to the problems of difficult,labor-intensive and inefficient lotus root harvesting,and based on the current research status that large lotus root diggers are difficult to move and small lotus root diggers are underpowered,this study proposes a twin screw propelled lotus root digger.Completed the overall design and calculation of the root digger.The key components of the root digger were analyzed based on virtual simulation technology.After completing the prototype trial,performance tests on the root digger were carried out.There are the main research elements of this paper.(1)The overall design of the twin screw propelled root digger and the selection of the key components were completed.The lotus root dredger was equipped with a twin screw drive chassis as a travelling part,a hydraulic scouring system,a power system,a hydraulic control system and an oscillating scouring adjustment mechanism to complete the lotus root harvesting.Based on the chassis balance analysis,the design of the chassis structure parameters and the structural layout of the components were completed.Based on the water jet theory,the selection and verification of the pump were completed.The selection of engines and hydraulic components were completed,and the design of the drive train and handling system were carried out.The design of the adjustment mechanism for the oscillating scouring operation of the root digger was completed based on the graphical method.(2)The optimal design of the nozzle of the root digger was completed based on Fluent simulation tests.The nozzle type,constriction section structure and nozzle structure parameters were optimized using the turbulence intensity at the nozzle exit section and the pressure loss between the nozzle inlet and outlet sections as performance indicators.The orthogonal test was carried out to investigate the significance of the relationship between the nozzle structure size and the scouring performance of the hydraulic scouring system,using the nozzle inlet inner diameter,constriction angle and outlet straight section length as test factors.The test results show that the cone-column nozzle produces a jet with good agglomeration,slow velocity decay and high scouring capacity.The better parameters of the nozzle were determined,which means that the nozzle has a better scouring performance when the inner diameter of the nozzle outlet of 16 mm,the inner diameter of the nozzle inlet of 40 mm,the contraction angle of 30° and the length of the straight cylindrical section of the outlet of 20 mm.(3)The key parameters of the travelling chassis of a twin screw propelled root digger were designed based on the Recur Dyn-EDEM coupled simulation test.And,the main factors affecting the travel performance of the twin screw drive chassis and their influence trends were investigated in order to obtain better structural parameters for the twin screw drive chassis.With reference to the theory related to ground travel machinery,the interaction between the helical blades and the soil during chassis propulsion was analyzed.The orthogonal test was carried out using the helix lift angle of the spiral blade,blade height to diameter ratio and float length to diameter ratio as test factors to investigate the trend and significance of each factor on the rotational resistance moment,propulsion slip rate and propulsion speed coefficient of variation of the drum.After the range analysis and the variance analysis of the simulation results,the optimal key parameters for the spiral drum were obtained using the integrated balance method: spiral drum diameter 500 mm,blade helix lift angle 30°,spiral blade height to diameter ratio 0.2 and drum length to diameter ratio 4.(4)The performance tests of the twin screw propelled root digger were carried out to analyze and study the working performance of the components.The factors influencing the performance of hydraulic flushing were investigated through single-factor tests and BoxBehnken central combined design tests.Experiments show that the nozzle outlet pressure of 0.30 MPa and above,nozzle and mud surface horizontal angle of 60 °,nozzle outlet close to the surface of the soil when the hydraulic flushing system has a better flushing performance.The propulsion performance test of the twin screw drive chassis was carried out to investigate the hydraulic motor inlet and outlet pressure,screw drum speed,screw propulsion distance,drum sinkage and propulsion slip rate under different motion conditions of the screw propulsion chassis,and to comprehensively evaluate the propulsion performance of the twin screw drive chassis.The test results of the key components of the root digger show that all components can meet the adaptation requirements of the root digger.