| With development of China's corn mass production and high-level concern over corn yield,higher demand on seeding quality had been drawn by large-scale manager,specially,precision planting was realized under the condition of high density,high speed and high efficiency,which could be met by high quality corn seed-metering device.The top working speed of seed-metering was between 6km/h and 8km/h in china,the main factor was seed-metering performance at high working speed and it is hard to realize high speed sowing.To solve this problem,a new type corn precision seed-metering device with double spoon wheel was developed,which could improve single grain performance:(1)The double spoon wheel corn precision seed-metering device is studied on the basis of the traditional type spoon wheel seed metering device,which combines the double spoon wheel with the double delivery wheel.To ensure the stability of the grain in the spoon wheel and induce the qualified index by reducing the rotational speed of the seed-metering device.(2)The basic form of seed-metering device is determined by analyzing the force and the movement about the process of seed filling,seed cleaning,seed delivery,seed protecting and seed throwing.The mathematical model of the seed-metering device in each movement process is established.(3)Through theoretical calculation,the main structural parameters are determined: the bulkhead angle of the seed metering device is 75 degrees,the initial delivery position is 55 to 75 degrees,the position of the seed throwing is 40 to 55 degrees,and the limit rotational speed is 73.1 r/min.Through the simulation analysis of the discrete element software EDEM,it is proved that the seed filling is filled with three ways of filling space,opposite direction movement and same direction movement,and the rate of seed filling can reach 100%.The test shows that the position of the seed delivery determines the effect of the seed clearing,the grain slips and jumps in the seed delivery wheel before the seed throwing and the grain bounces,rolls and slides on the seed bed after throwing.(4)Several parameters were fixed including the best position of the seed throwing,the optimum range of rotational speed and the most optimal position of the seed delivery by single factor experiment of position and speed of spoon-wheel,the reason why seed-missing index decreased sharply was found out at high rotational speed by comparison between seed-missing index and seed-filling index.(5)The effects of speed fluctuation,vibration and seed bed topography are analyzed to research on the homogeneity of plant spacing.The experimental results show that the rotational speed can affect the spacing of the plant spacing by throwing distance,the beneficial vibration can improve the performance of the seed row and the uniformity of the ground surface is beneficial to the improvement of the uniformity of the plant spacing.The simulation was done to get governing equation of qualified index by regression analysis,and accuracy of governing equations' prediction was validated.(6)The results show that the performance of the double spoon wheel seeding device is close to the picker finger and single spoon wheel under the medium and low speed conditions.When the speed is 10.152km/h,the qualification index of the double spoon wheel seeding device is 86.63%,which is obviously higher than the picker finger and single spoon wheel.The operation effect of double spoon wheel seed-metering device meets the requirement of 80% in the technical condition of single grain(precision)seeder. |
PDF Full Text Request