Design And Experiment Of Mud-taking Device For Self-propelled Rice Field Seedling Machine

Rice machine transplanting can alleviate stubble conflicts in multi-crop areas and achieve high and stable yields.The problems of difficult preparation of rice seeding soil and more labor for rice seedling still exist in the factory and traditional field rice seedling currently used in China,restricting the promotion and application of machine transplanting technology.This thesis combines the requirements of agricultural machinery and agronomy,through experimental determination of physical parameters,theoretical modeling,structural design,simulation optimization and soil-bin/field verification tests,to develop self-propelled field mud-taking device,the main contents and conclusions are as follows:（1）Experimental study of paddy soil material properties testing.The measured sample mud had a plastic limit of 15.67%,a liquid limit of 26.10%and a plasticity index of 10.63%,a mean particle size of 0.02 mm,and the percentages of clay,powder and sand were 23.11%,30.78%and 46.11%,respectively,the rheological properties showing a characteristic shear dilution thixotropic effect,which was in high agreement with the H-B rheological model.（2）Overall design of mud-taking device for self-propelled rice field seedling raising machine.The overall structure,key and main components of the mud-taking device were designed,and the force power consumption and movement process of the auger for mud-taking were analyzed,which resulted in the spiral outer diameter D of 240 mm,pitch S of192～288 mm,shaft diameter d of 70 mm,rotational speed n of 60～140 r/min,and mud-taking depth H of 60 mm;the first 6th order inherent frequency of the auger for take mud was between 141.75～275.56 Hz,and the excitation frequency of 1.00～2.33 Hz was much smaller than the intrinsic frequency,and the deformation was much smaller than the theoretical value,so the structure will not be deformed and damaged by resonance.（3）Simulation experiment of the operational performance of the mud-taking device.The discrete element model parameters of the paddy mud with a water content of 38%were calibrated by combining the virtual simulation and physical measurement tests.A discrete element simulation model of mud extraction device-mud interaction is established based on EDEM 2018 software,including the single-factor simulations,and multi-factor of response surface test simulations were conducted with the pitch,rotational speed and forward speed of the auger for mud-taking as the test factors.Afterwards,the results are processed and optimized using Design-Expert 12 software to obtain the optimal combination of structural and operating parameters:the auger pitch of 192 mm,the rotational speed of132 r/min and the forward speed of 0.19 m/s,and the average value of the software-optimized of mud-taking weight Y₁ was 7.98 kg and the coefficient of variation Y₂ was 1.28%;The optimal combination of parameters for the simulation test with average value of the mud-taking weight Y₁ was 8.18 kg,and the coefficient of variation Y₂ was 1.31%,with the relative errors to the software optimized values were 2.44%and 2.29%,respectively.（4）Soil trough and field trials of the mud-taking device.The self-propelled rice seedling raising for mud-taking performance test bench was built to verify the optimal performance under the optimal parameters combination,with the mean value of mud-taking weight in soil-bin test was 7.82 kg,with the coefficient of variation was 1.38%,and the error of actual simulation test were 4.60%and 5.07%,respectively.The surface flatness was 10 mm and the mean torque value was 218 N·m.The actual operating performance and adaptability of the whole machine were verified through field performance tests.