| As one of the major crops in China,rice production determines food security in China and the world.There is a big gap between the mechanization level of rice planting in China relative to Japan and South Korea,so it is of great significance to improve the mechanization level of rice planting in China for rice production and food security.The transplanting mechanism with planetary elliptic gears is the main working part of the high-speed rice transplanter,and its working performance directly determines the comprehensive level of high-speed rice transplanter.At present,the transplanting mechanism with planetary elliptic gears of high-speed rice transplanter has problems such as fluctuation of the working speed of the transplanting mechanism due to vibration,deviation of the running trajectory and poor planting quality.Therefore,in this thesis,the vibration response of the seedling pushing device of the transplanting mechanism with planetary elliptic gears is analyzed,and on this basis,the single-factor and three-factor five-level orthogonal test are carried out.A regression analysis of the simulation test results is accomplished,and the simulation optimization results are verified through bench tests.The main research contents and results of this paper are as follows.(1)Analysis of the dynamic performance and vibration response of the transplanting mechanism with planetary elliptic gears.Based on the structure and working principle of the transplanting mechanism with planetary elliptic gears,the working process of the transplanting mechanism is analyzed,the main structure and process of the vibration generated by the transplanting mechanism are determined,and a two-degree of freedom vibration response model is established and the model is analyzed and calculated.The results show that the operating speed,counterweight mass and spring stiffness of the transplanting mechanism with planetary elliptic gears have significant effects on the vibration response of the planting arm casing of the transplanting mechanism with planetary elliptic gears.As the operating speed and the stiffness of the pushing spring increase,the vibration response of the transplanting mechanism increases;as the mass of the counterweight increases,the vibration response of the transplanting mechanism decreases.(2)Simulation test and analysis of the transplanting mechanism with planetary elliptic gears.A multi-body dynamics model of the transplanting mechanism with planetary elliptic gears was established,and the variation of the maximum contact force and unevenness coefficient with operating speed,counterweight mass and spring stiffness were obtained through single-factor tests,and the optimal intervals of the three were obtained.A regression analysis was fulfilled to establish the regression equations between the operating speed,counterweight mass,spring stiffness and the contact force and unevenness coefficient,and the variance analysis was carried out on the regression equations.The regression equation was analyzed for variance and two optimal combinations of parameters were obtained by multi-objective parameter optimization: Optimization group 1: operating speed of 250.0 r/min,counterweight mass of 0.9 kg and pushing spring stiffness of 140.0 N/m;Optimization group 2:operating speed of 200.0 r/min,counterweight mass of 1.0 kg and pushing spring stiffness of 200.0 N/m,where the contact force was 5.21 N and the inhomogeneity coefficient was 3.025.The maximum stress and uprightness were used as indicators to verify the planting quality of the optimized group parameters.The results showed that compared to the control group,the maximum stress in the optimized group 1 and 2was reduced by 17.8% and 12.5% respectively,and the uprightness was increased by4.4% and 2.2% respectively,indicating that the results of the simulation test parameters of the optimized group could reduce the damage to the seedlings and improve the planting quality of the seedlings.(3)Bench verification test of the transplanting mechanism with planetary elliptic gears.A high-speed rice transplanter splitting and transplanting mechanism comprehensive performance test bench is designed and its structural composition and working principle are introduced.The maximum stress value of the test bench is less than 5.41%,the uprightness is less than 3.10% and the unevenness coefficient is less than 6.12%,i.e.the simulation and bench test results are consistent.The results show that when the operating speed is 250.0 r/min,the counterweight mass is 0.9 kg and the spring stiffness is 140.0 N/m,the working performance and planting effect are the best,with a maximum stress value of 6.05 MPa,uprightness of 93.58% and an unevenness coefficient of 3.16,which is 18.79% lower than the maximum stress value of the control group.The maximum stress value was 18.79% lower,the degree of uprightness was 5.99% higher and the unevenness coefficient was 28.67% lower than that of the control group,which effectively reduced the force of the transplanting mechanism with planetary elliptic gears on the seedlings and improved the operational quality effect. |
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