Design & Research Of Mechanism For Variable Sowing On 2BFQ-6 Rape Precision Combined Direct Planter

Mechanized planting operation for rape closely relates with different sowing density of rape under various sowing dates, the fertilizing amount, the amount of previous crop stalk, the soil moisture and so on. Feasible sowing density of rape under various sowing dates is vitally important, and the adjustment of sowing quantity directly affects the operating effect of the planter and the subsequent crop's yield. The planting quantity of crops had been counted by the unit of Jin, but it is counted by particle nowadays. The adjustment of sowing quantity can realize the precision sowing and sow seeds to ideal positions so that it makes crops grow better. The precision sowing has the advantages of making plants' density feasible, seeds saving, fertilizer saving, labor saving, time saving, light and ventilation, increasing production obviously.Based on different planting conditions and sowing time in the same place, there are different sowing density's requirements of rape respectively. So the mechanism for variable sowing on 2BFQ-6 rape precision combined direct planter has been developed depending on the theory that adjusting the engaging relations of gears can change the input shaft's speed of the metering device. The main research contents of this paper are as follows:(1) Systematically analyzed the status and the development of the mechanism for variable sowing of different types at home and abroad. On this basis, general technical scheme on the mechanism for variable sowing on 2BFQ-6 rape precision combined direct planter has been determined in consideration of the agricultural machinery and agronomical specific requirements. The mechanism for variable sowing that has the regulatory function with four planting densities has been designed. At the same time some main structural and performance parameters have been presented. Four planting densities that the mechanism for variable sowing could realize are:15.75 thousands plants/mu,22.50 thousands plants/mu,28.00 thousands plants/mu,40.00 thousands plants/mu.(2) By adopting kinematics and dynamics, the transmissing process of the mechanism for variable sowing has been analyzed and studied so as to obtain the scope of the gear-shafts'rotating rate and the peripheral speed of meshing gears. Then the analysis of angular speed and angular acceleration of driven gear have been analyzed and studied so as to achieve their mathematical expressions. Gear pairs have been simplified into the model of non-linear dynamics with single degree of freedom considering time-varying meshing rigidity and flank clearance. Through analysis of intensity, some conclusions have been reached that the influence of tooth number on the transmission capacity of the gears is regular and the carrying capacity of each gear was discovered.(3) The paper analyzed the stress distribution and the strain law of the gear engagement on the nonlinear contact using ANSYS software, so the displacement, strain and stress distribution produced by gear engagement have been obtained. At the same time, the displacement, strain and stress distribution of each gear-shaft have been obtained using the linear static analysis. Finally, modal analysis of each gear-shaft has been developed, and the results show that all the gear-shafts meet the working requirements of stiffness. Finally, some structural improving measures of the mechanism for variable sowing have been presented.(4) The bench tests on the adjusting error rate of the sowing amount for the variable sowing mechanism have been carried out. The influencing law of each factor on the test index is obtained by single factor experiment, and the best range combination of working parameters is also got by the orthogonal experiment. At the same time, the changing trends produced by the vacuum pressure and transmissing ratio have been obtained when the input-gear axis's speed is maximium or minimium. The inner rules on the adjusting error rate of the sowing amount have been presented too. The bench tests approved that the error ratio between the sowing amount of the metering device when the mechanism for variable sowing is not installed and the one of the metering device when it is installed is less than 10% at the same time and under the same conditions. It can satisfy the requirements of rape's variable sowing.