| With the improvement of the level of agricultural mechanization in my country,the application of small agricultural machinery is becoming more and more common,but this type of machinery is light in weight,large in vibration and unstable in performance.The field vibration of the fertilizer applicator causes a large coefficient of variation in the amount of fertilizer applied,and there are few reports on the effect of the vibration of the fertilizer applicator on the fertilization performance.Therefore,this paper analyzes the vibration characteristics of the small hole fertilizer machine,establishes a mathematical model of the vibration of the small hole fertilizer machine,and explores the influencing factors of its vibration.The mathematical model of the fertilization amount and the vibration factors of the fertilizer applicator is established,and the fertilization performance under the vibration condition is analyzed by using the EDEM discrete element simulation software.Based on the above analysis,the field vibration fertilizer discharge experiment was carried out,and the simulation results and mathematical model were verified by the experiment,which provided a reference for the research on the fertilizer discharge mechanism of the small hole fertilizer machine.The main research contents are as follows:1.Through the analysis of the vibration characteristics of the small hole fertilizer machine,the mathematical model of the fertilizer machine vibration was established,and its influencing factors were analyzed,and it was concluded that the driving speed was the most important factor affecting the vibration frequency and vibration acceleration of the fertilizer machine.The angle formed by the ridge(that is,the unevenness of the ground surface)mainly affects the vibration acceleration,and the counterweight mainly affects the vibration frequency of the machine.2.The fast Fourier transform analysis and wavelet transform analysis were carried out on the fertilizer discharge device and the handrail of the small hole fertilizer machine.(1)Using the method of fast Fourier transform analysis,the vibration characteristics of the fertilizer discharge device and the handrail of the fertilizer applicator at different driving speeds were analyzed.At the speed of 0.7m/s-1.5m/s,it increases with the increase of the speed;when v=0.5m/s,the vibration frequency of the fertilizer discharge device is close to its natural frequency,which will generate resonance.The natural frequency range of the fertilizer removal device is 4.39Hz-41.10 Hz,and the natural frequency range of the handrail is 5.01Hz-17.69 Hz.(2)The method of wavelet analysis was used to analyze the vibration signal of the fertilizer discharge device of the fertilizer applicator and the handrail,and it was found that the unevenness of the road surface was an important factor affecting the frequency of the vibration signal,and when driving at a high speed,the vibration signal The frequency and size change greatly,and the speed of 0.7m/s to 1m/s should be used as much as possible during work.In the decomposition and reconstruction of the vibration signal,the vibration signals of the fertilizer removal device and the handrail are composed of several sine wavelet bases.Singularities are detected in the detail signal of the 2-level wavelet decomposition of the handrail signal,which can be used to detect the fault of the transmission system.3.Mathematical models of fertilization amount and vibration factors were established,and fertilization simulation experiments were carried out under different vibration conditions.(1)The driving speed of the fertilizer applicator was fitted with the vibration frequency,vibration acceleration and amplitude,and it was found that the fitting effect was the best with the vibration acceleration.(2)Fertilizer discharge simulation tests were carried out with and without vibration condition setting respectively,and it was found that under the action of vibration,the kinetic energy of fertilizer was large,the vibration was large,and the smoothness of fertilizer discharge was good,and with the increase of vibration acceleration.The larger the amount,the larger the amount of fertilization.The coefficient of variation of fertilizer application increases first and then decreases with the increase of vibration acceleration.The first increase is because when the vibration acceleration increases,the amount of fertilizer discharge increases,and the amount of fertilizer changes greatly,and then decreases because of vibration.When the acceleration reaches a certain value,the amount of fertilizer discharge reaches saturation,so its change is small and the coefficient of variation decreases.(3)Simulation tests were carried out on fertilizer discharge performance of different groove section shapes of fertilizer discharge wheel shaft,in which B section shape had the lowest coefficient of variation and the best performance of single hole fertilizer discharge performance.Through the simulation test,it is found that the error between theoretical calculation value and experimental value increases with the increase of the working length of the fertilizer discharge wheel shaft.When the working length of the fertilizer discharge wheel shaft is 15 mm,30 mm and 50 mm,the mean relative error is 7.83%,4.84% and 3.86%,respectively.4.Field experiments were carried out and different excitation conditions were set.When the excitation conditions are 0 cm,3 cm and 6 cm,the mathematical model and simulation test of fertilizer application amount are verified.Under different excitation conditions,the errors of fertilizer application amount in field test and simulation test were 4.72%,4.33% and3.49%,respectively.The relative errors of theoretical calculation value and experimental value were 4.53%,3.84% and 2.85%,respectively. |
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