| Corn is the first grain crop,an important feed and industrial raw material,while soybean is an important oil crop and edible plant protein source in our country,which has a great influence on the development of the whole national economy.However,because large-scale planting in our country is less,mechanization level is relatively reduced,and agricultural production cost remains high.Increasing investment of intelligent agricultural machinery equipment of corn and soybean is one of the important ways to reduce planting cost and improve international competitiveness.Sowing operation is one of the most important links in the process of field agricultural production,which directly affects the subsequent germination,emergence,growth and yield of crops.Therefore,improving the quality of sowing operation is an important premise and basis for ensuring our food security and promoting agricultural increase and income through mechanization under the condition of limited cultivated land resources.In the process of high-speed sowing operation,due to the influence of different seed incidence angles,machine vibration,tilt and other factors,the seeds in the seed guide tube produce disorderly collision,so that it can not move according to the predetermined trajectory,resulting in poor uniformity and stability during the transfer of seeds,seriously affecting the sowing accuracy,with the increase of operation speed,this problem is more prominent.In order to reduce the disorderly collision of seeds in the guide tube and improve the uniformity and stability of seed transport,an active brush wheel type seed introduction mechanism is designed,which forces the seeds to slide down to the bottom of the seed groove in an orderly manner along the centerline of the back wall of the seed guide tube through the active guidance and secondary seeding of the active rotating brush wheel,so as to avoid disorderly collision in the guide tube and significantly improve the sowing accuracy under high-speed working conditions.The main research contents of this paper are as follows:(1)A kind of active brush wheel seed guide component was designed which could effectively improve the motion trajectory of seeds in the seed guide tube.Through theoretical calculation and kinematic analysis,the equation of seed guide curve was obtained:Y=-0.02x~2+3.9x,the optimal section size of U-shaped groove:height L=58 mm,width W=24mm,size range of flexible brush wheel:50～66 mm,and the motor control system of the flexible brush wheel and the speed of the seed dispenser is synchronized,which provides a reference for the structural design of the seed guide parts.(2)To obtain the optimal structural parameter range of the seed guide component of the active brush wheel and improve the working quality of the seed guide device,virtual simulation analysis was carried out on the seed delivery process of the seed guide device using EDEM simulation software,and the seed movement trajectory was observed.According to the size characteristics of different varieties of seeds,the gap size between flexible brush wheel and U-shaped groove guide tube was obtained.The best gap size was 7.1 mm for soybean seeds and8.0 mm for corn seeds.(3)According to the theoretical analysis,the main factors that affect the working performance are the working speed of seed separator,the diameter of brush wheel and the speed of brush wheel.An active brush wheel seed guide component test rig was built,and parameter optimization tests were carried out.The combined design method of three-factor and five-level quadratic regression orthogonal rotation test was adopted,and the qualified rate of grain spacing,seeding leakage rate and the coefficient of grain spacing variation were selected as evaluation indexes.The test results showed that:When the working speed,brush wheel diameter and brush wheel speed were 30 r/min,66 mm and 850 r/min,respectively,the seed guide uniformity and stability of soybean seeds were the best.The pass rate of seed spacing was 95.98%,the leakage rate was 0.36%,and the coefficient of variation of seed spacing was 15.58%.When the working speed,brush wheel diameter and brush wheel speed were 30 r/min,66 mm and 550 r/min,the seed guide uniformity and stability of corn seeds were the best.The pass rate of seed spacing was 95.75%,the leakage rate was 2.75%,and the coefficient of variation of seed spacing was17.23%.(4)The performance test of the active brush wheel seed guide mechanism was carried out.The test results showed that:Under the same operating speed,the operating effect of the active brush wheel type seed guide component was obviously better than that of the ordinary seed guide tube.At a higher speed(forward speed about 12 km/h),the active brush wheel type seed guide component could still maintain a higher qualified rate of 91%of the seed spacing,and the qualified rate of the active brush wheel type seed guide component could increase by 11.36%compared with the ordinary seed guide tube.At the same time,the experimental results show that the active brush wheel seed guide device has good adaptability under different seed types and different seed disperser types. |
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