气吸式免耕播种机振动特性及其对排种性能的影响研究

发布时间：2019-01-05 05:33

【摘要】：为了提高气吸式免耕播种机在免耕地播种作业的质量,开展了气吸式免耕播种机振动特性对排种性能的影响研究。本研究测试分析了免耕播种机在不同免耕地的振动特性,建立了免耕播种机在振动条件下的数学模型,并分析其影响因素;利用离散元分析软件仿真分析了排种器内种群的运动和受力情况,优化了排种器的工作参数;搭建了振动式排种性能试验台;进行了排种性能试验,得出排种器工作和结构参数的最优组合。研究结果如下:1.通过分析播种机的振动特性,建立了气吸式免耕播种机振动的数学模型,分析了其影响因素,并求出了播种机振动固有频率,得出播种机垂直振动有两阶振型。同时分析了种子的气吸和振动耦合力学特性,得出吸附种子的临界真空度。2.对免耕播种机在不同免耕留茬地表作业时进行振动测试,获得了免耕播种机在不同免耕地表振动特性的共性和差异性。通过分析葵花、玉米、莜麦、荒地四种免耕地振动能量的密度分布和在不同播种速度下各免耕地振动频率和振幅的关系变化得出:(1)影响播种机垂直振动的因素主次顺序是播种机前进速度、垄向、播种深度。(2)排种器振动能量在免耕地的频率分布密度主要集中在低频段0～12Hz,且与根茬种类、土壤坚实度和含水量有直接关系,土壤坚实度和含水量越大的根茬免耕地,其振动能量越大。四种免耕地的振动能量主次顺序是葵花地玉米地莜麦地荒地。排种器的振动频率和振幅随着播种机前进速度的增大而增大。免耕地根茬的大小和密度是排种器振动频率和振幅的影响因素,免耕地作物根茬越大,密度越大,则振动频率和振幅随之增大。3.振动信号通过模态参数识别,确定了振动系统的物理参数。玉米茬地两个振型的自然频率为8.5Hz和38.5Hz,与之相应的模态阻尼比为0.075。4.对不同免耕地振动信号进行分解和重构。(1)分解信号显示免耕茬地和退耕荒地的振动信号由若干尺度函数基和正弦小波基组成。(2)重构信号显示免耕茬地的波形均出现间隔,而荒地的波形呈连续变化。原因是免耕地表存在规律的株距根茬,而荒地蒿草的根茬无规律。5.以振动频率、振幅、排种盘转速(即搅种轮转速)、种箱内种子的容种量为变量,种子速度、种子间作用力和离散度为目标函数,借助离散元软件仿真种箱内大豆种群运动,得出优化的工作参数范围为:排种盘转速应选择14.80～18.50r/min;频率应选择小于10Hz;振幅应选择小于5mm;容种量应选择60%～80%。这样可使种箱内种子处于利于吸种的松散状态,减小吸种时种子间的拖带和碰撞作用,提高种子吸附性能。工作参数对种子间作用力的交互作用分析结果佐证了上述单因素分析的正确性。该结论通过吸种率的单因素试验得到了验证。6.以排种器的工作和结构参数(排种盘转速、真空度、容种量、频率、吸种孔直径和吸种孔分布直径)为试验因素,合格指数、重播指数、漏播指数为评价指标,对排种器进行了排种性能的响应面法优化试验,以合格指数最大、漏播指数最小为响应值,响应面最优值结果为:吸种孔分布直径为170mm、吸种孔直径为3.77mm、真空度为3.88～3.97kPa、排种盘转速为11.02～15.96r/min、频率小于7Hz。本研究的结论对高寒干旱地区气吸式免耕播种机的设计具有一定的实际应用价值。
[Abstract]:In order to improve the quality of the air-suction type no-tillage seeding machine in the no-tillage land, the effect of the vibration characteristics of the air-suction type no-tillage seeder on the performance of the row is carried out. The vibration characteristics of no-tillage planter under the condition of no-tillage are analyzed and the mathematical model of no-tillage seeding machine under the condition of vibration is established, and the influencing factors are analyzed. The motion and the stress of the population in the no-tillage seeding machine are analyzed by using the discrete element analysis software. The working parameters of the seed bank are optimized, the vibration type row performance test bed is set up, and the performance test is carried out, and the optimal combination of the work and the structural parameters of the seed bank is obtained. The results of the study are as follows: 1. By analyzing the vibration characteristics of the seeding machine, the mathematical model of the vibration of the air-suction type no-tillage seeding machine is established, the influencing factors are analyzed, and the vibration natural frequency of the seeding machine is obtained, and the vertical vibration of the seeder is obtained with two-order modes. At the same time, the mechanical properties of the gas absorption and vibration of the seeds were analyzed, and the critical vacuum degree of the adsorption seed was obtained. The vibration test of no-tillage planter on the surface of the no-tillage and stubble-retaining surface is carried out, and the common and the difference of the no-tillage seeding machine in the different no-tillage ground surface vibration characteristics are obtained. By analyzing the density distribution of four no-tillage ground vibration energy of the sunflower, the corn, the wheat and the wasteland and the relationship between the vibration frequency and the amplitude of the no-tillage ground under different seeding speed, the main and secondary order of the vertical vibration of the seeding machine is the advancing speed of the seeding machine, the ridging direction, Sowing depth. (2) The frequency distribution density of the vibration energy of the seed bank in the no-tillage land is mainly concentrated in the low-frequency segment of 0-12Hz, and is directly related to the type of the root, the solid degree of the soil and the water content, and the greater the soil firmness and the water content, the greater the vibration energy of the root stubble with the greater soil firmness and water content. The primary and secondary order of vibration energy of four no-tillage land is the land of the ground and the ground in the ground of the sunflower. The vibration frequency and the amplitude of the seed bank increase with the increase of the advancing speed of the seeding machine. The size and density of the root stubble in no-tillage land are the influencing factors of the vibration frequency and the amplitude of the seed bank, and the greater the root stubble, the higher the density, and the increase of the vibration frequency and amplitude. The vibration signal is identified by the modal parameter, and the physical parameters of the vibration system are determined. The natural frequency of the two modes of corn stubble is 8. 5Hz and 38. 5Hz, and the corresponding modal damping ratio is 0.075.4. and the vibration signals of different no-tillage ground are decomposed and reconstructed. and (1) the decomposition signal shows that the vibration signal of the no-tillage stubble land and the uncultivated land is composed of a plurality of scale function groups and a sine small wave group. (2) The reconstructed signal shows the interval of no-tillage stubble, and the waveform of the uncultivated land is changed continuously. The reason is that there is no law on the surface of the no-tillage land, and the root of the grass in the wasteland has no rule. Based on the vibration frequency, the amplitude and the rotation speed of the seed plate (that is, the rotation speed of the stirring wheel), the capacity of the seed in the seed box is the variable, the seed speed, the seed-to-seed acting force and the dispersion degree are the objective function, the soybean population movement in the seed box is simulated by means of the discrete element software, and the optimized working parameters range is as follows: The speed of the seed plate shall be 14.80 ~ 180.50r/ min; the frequency shall be less than 10Hz; the amplitude shall be less than 5 mm; the volume of tolerance shall be 60% ~ 80%. so that the seed in the seed box is in a loose state which is beneficial to the seed absorption, the drag belt and the collision effect between the seeds are reduced when the seed is absorbed, and the adsorption performance of the seeds is improved. The results of the interaction between the working parameters and the seed-to-seed interaction support the correctness of the above-mentioned single-factor analysis. This conclusion was verified by the single factor test of the rate of seed absorption. taking the working and structural parameters of the seed bank (the rotation speed, the degree of vacuum, the volume of the seed, the frequency, the diameter of the seed suction hole and the distribution diameter of the seed suction holes) as the test factors, the qualified index, the replay index and the leakage index as the evaluation index, The response surface method was used to optimize the discharge performance of the seed bank, with the highest qualified index and the minimum leakage index as the response value. The best result of the response surface was that the distribution diameter of the seed suction holes was 170mm, the diameter of the seed suction holes was 3.77mm, the degree of vacuum was 3.88 ~ 3.97kPa, and the rotation speed of the discharge disk was 11.02 ~ 150.96r/ min, and the frequency was less than 7Hz. The conclusions of this study have some practical application value to the design of the air-suction type no-tillage seeding machine in the high and cold area.
【学位授予单位】：内蒙古农业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S223.2

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