| Seeding accuracy is one of the main factors affecting the effect of precision sowing.At present,precision seeders in China mainly use ordinary circular seed guide tubes as seed guide devices,during the operation process,the disorderly collision between the seed and the inner wall of the seed guide tube leads to an increase in the variation coefficient of seed pitch and reduces the sowing quality.In this paper,we design an adaptive seed guide device that can automatically adjust the seed guide curve and the installation angle of the seed guide tube according to the change of the rotational speed of the seed discharge shaft.The main research of the paper is as follows:(1)Determination of physical characteristics of maize seeds.In order to analyse the movement of the seeds in the seed guide tube and to set the parameters in the simulation,the physical characteristics of three types of maize seeds,namely Zhengdan 958,Zhongke Dongyu 215 and Xiangyu 998,such as triaxial size,moisture content,100 grain weight,density,static friction coefficient,dynamic friction coefficient and collision recovery coefficient,were measured.The results of the measurements showed that the physical characteristics of the maize seeds differed little from each other,so Zhengdan 958 seeds were selected for the subsequent study.(2)Design of key components of the adaptive seed guide.An adaptive seed guiding device was designed to monitor the rotational speed of the seed discharge shaft in real time and adjust the seed guiding curve and the installation angle of the seed guiding tube according to the rotational speed of the seed discharge shaft.The size of the seed guide tube is designed according to the installation space of the seed guide tube in the notill planter,and the seed guide tube adjustment device and the supporting electronic control system are designed to improve the seed guide uniformity of the no-till planter.(3)Simulation and optimisation of seed guide components based on EDEM discrete element software.The contact model between the maize seed,seed rower and seed guide was established,and the central combination(CCD)test with seed rowing shaft speed,seed guide installation angle and seed sphericity as factors,grain spacing variation coefficient and seeding pass rate as indicators was carried out by means of discrete element numerical simulation,and the test data was processed by Design-Expert software.The test results showed that in the low-speed seed guide test,the seed guide performance was optimal when the seed discharge shaft speed was30r/min,the seed guide tube installation angle was 80°,and the seed sphericity was greater than0.78%,and the pass index and the coefficient of variation of grain spacing were 94.45% and8.15% respectively.In the high-speed seed guide test,the seed guide performance reached the optimum state when the speed of the seed discharge shaft was 50r/min,the installation angle of the seed guide tube was 70°,and the seed sphericity was more than 0.78.(4)Field test of the adaptive seed guide.In order to verify the actual operation effect of the adaptive seed guide device,a field comparison test was designed to compare the operation effect of the adaptive seed guide device with that of the common circular seed guide tube.When the sowing speed was 4km/h,the seeding quality of the adaptive seed guide and the common arc seed guide were 92.23% and90.62% respectively,and the coefficient of variation of plant spacing was reduced by 5.86%;when the sowing speed was 8km/h,the seeding quality of the adaptive seed guide and the common arc seed guide were 89.25% and 86.52% respectively,and the coefficient of variation of plant spacing was reduced by 4.69%;when the sowing speed was 12km/h,the seeding quality of the adaptive seed guide and the common arc seed guide was reduced by 4.69%.the seeding speed was 12km/h,the seeding quality of the adaptive seed guide device and the ordinary circular seed guide tube were 85.43% and 74.32% respectively,and the variation coefficient of plant spacing was reduced by 9.54%;... |
PDF Full Text Request