Study On Vibration Characteristics Of Air Suction No-Tillage Planter And Its Effect On Seed Metering Performance

In order to improve the quality of air suction no tillage seeder in uneven no tillage sowing.This study tested and analyzed the vibration characteristics of no tillage planter in different free farmland,Deduced the mathematical model of the seeder and its seed metering device under vibration condition,the influencing factors are analyzed by mathematical model;With the help of discrete element analysis software,the movement and force of seeds group in the seed metering device are analyzed,optimizing the working parameters of seed metering device;A vibration type seeding test bed was set up,and the seeding performance test was carried out;Further optimization of work and structural parameters.The results are as follows:1.By analyzing the vibration mechanism,the mathematical model of the vibration of air suction no till seeder was established and its influencing factors were analyzed,the natural frequency of vibration of the planter is obtained,it is concluded that there are two modes of vertical vibration of the planter.At the same time,the mechanical characteristics of gas suction and vibration coupling are analyzed,the critical vacuum degree is obtained.2.The vibration test of different stubble of no-tillage farmland surface,Generality and difference of vibration characteristics of different no tillage farmland surface.Through the analysis of sunflower,corn,oats,wasteland four no tillage farmland vibration energy density distribution and the relationship between the vibration frequency and amplitude of the no tillage sowing at different speeds,draw the conclusion:(1)The primary and secondary order of the factors affecting the vertical vibration of the planter is the advance speed of the no-tillage planter,ridge direction and sowing depth.(2)The frequency distribution of the vibration energy of the seed metering device in no-till farmland is mainly concentrated in the low frequency 0-12Hz,and it was directly related to the type of root crop,soil firmness and water content,the root stubble no-till farmland greater of the soil hardness and water content,the greater the vibration energy.The primary and secondary order of vibration energy of four kinds of no tillage farmland is sunflower,corn,oats and wasteland.The vibration frequency and amplitude of the seed metering device increase with the increase of the advance speed.The size and density of root stubble are the factors that affect the vibration frequency and amplitude,the bigger the root stubble is,the bigger the density is,the more the vibration frequency and amplitude increase.3.Modal parameter identification of vibration signal,the physical parameters of the vibration system are determined.The natural frequencies of the two vibration models of maize stubble field are 0.085rad/s and 0.385rad/s,the corresponding modal damping ratio is 0.075.4.Using Matlab software to decompose and reconstruct the vibration signals of different no tillage farmland.(1)The decomposition signal shows that the vibration signal of no tillage stubble land and abandoned land is composed of several scale function and sine wavelet base.(2)The reconstructed signal showed that the wave shape of no tillage stubble farmland was interval.and the waveform of the wasteland is continuous and periodic change.The reason is that there is no tillage stubble with regular spacing,The wormwood stubbles of abandoned farmland get out of order.5.The vibration frequency and amplitude,the rotation speed of the seed wheel and the amount of seed in the seed box were taken as dependent variables,The seed velocity,the interaction force between seeds and the dispersion are the objective functions.Simulation of soybean seeds group movement in seed box with discrete element software,it is concluded that the optimized working parameters range:seed wheel speed should be selected from 14.80 to 18.50 r/min;the frequency should be less than 10 Hz;the amplitude should be less than 5 mm;the capacity of seeds should be selected from 60 to 80%.In this way,the seeds in the seed box are in a loose state which is favorable for sucking seeds,to reduce the effect of seed entrainment and collision when sucking seeds,Improve seed adsorption performance.The interaction analysis of the working parameters on the interaction force between seeds,which proves the correctness of the single factor analysis.The results were verified by the single factor test of the sucking rate.6.Taking the working and structure parameters of seed metering device as test factors,which are as follows:the rotation speed,the vacuum degree,the capacity of the seed,the diameter of the suction hole and the distribution diameter of the suction hole,qualified sowing index,repeat sowing index,and leakage sowing index were evaluating indicator,the response surface methodology was used to optimize the seed metering performance of seed-metering device.The maximum value of the qualified index and the minimum of the leakage index were the response values,response surface optimization results for:the diameter of the suction hole is 170mm,the diameter of the suction hole is 3.77mm,the vacuum degree is 3.88-3.97kPa,the speed of the seeding shaft is 11.02-15.96r/min,the frequency is less than 7Hz.The conclusion of this research has certain practical value for the design of air suction no tillage planter in cold and arid regions.