| Rise,as one of the primary grain crops in China,with the annual planting area of 453 million mu,accounted for 27% of the total area of grain crops,the total output of over 200 million tons,32% of the total output of grain crops,is the highest grain crop in the country.However,the present level of rice planting mechanization in China is relatively low,which is a weak link in the whole process of rice production mechanization.In particular,hybrid rice transplanting emphasizes less sparse planting and relies on super tillering ability to increase yield.However,at present,transplanting is mainly done by manual transplanting,with great labor intensity and low seeding accuracy in the seedling stage of hybrid rice.Therefore,in order to improve the mechanical automation level of hybrid rice seedling raising,it is urgent to study the mechanism of the key technology of the precision breeding and seeding of hybrid rice,to provide a guarantee for mechanized transplanting and to make the yield advantage of hybrid rice play an important role.This paper,aiming at the problem of poor seeding stability and low accuracy in the precision plug seeding device of rice,designs a metering device with a combination of crossed diversion chamber and hill socket cylinder,with the methods of dynamics,bulk dynamics,theoretical analysis of particle flow,discrete element simulation and experimental research.The key technology of the device is systematically studied.The main contents and conclusions are as follows:(1)Based on the principle of cross species diversion,the dibble seeding device for indented cylinder chamber structure is designed.The overall structure and working principle of the cross guiding rice precision seeding device are introduced: accordingly,itis concluded that the key structural parameters affecting rice seed flow are the inclination angle of the seed plate,the transition radius of the crossing area,the opening gap and the incidence angle.It further clarifies the difference between the seed flow formation of the cross flow seed chamber and the formation of the seed flow in the direct acting seed chamber,which provides a theoretical basis for the design of the cross flow type room structure to provide a uniform seed flow for the precision seeding device of the rice precision cavern.(2)Based on the principle of particle flow,a kinetic model of rice seed particles in the seed chamber was established,the motion law of particle flow is analyzed,which leads to The obtaining of influence of seed chamber structure parameters on particle fluidity.The EDEM discrete element software is used to simulate the seed chamber flow,and the optimization of indoor structural parameters is realized.The kinematic model of the particle in the cross section of guide plate and diversion is established,and the influence of the inclination and length of the seeding plate on the seed layer is obtained,and the influence of the thickness of the seed layer on the guide plate and the opening gap in the crossing area on the flow of the indoor particles is obtained.By comparing the particle flow simulation results of different chamber structure parameters,it can be concluded that under the incident angle of 80 degrees,radius of the arc of 25 mm and 120 mm,a uniform particle flow can be formed in the indoor chamber,which is conducive to filling the seed rows of the hole seeding drum,and provides a theoretical basis for the structural design and optimization of the seed chamber.(3)Based on the principle of rice seeding drum filling,a kinematic model of rice seeds in filling area of seeding plant was established,and the influence of seeding device's structural parameters and working parameters on filling of rice seeds was analyzed.The discrete element software EDEM was used to simulate the filling performance of the seeding device,and the structural parameters of the seeding device were optimized.By establishing the dynamic model of the grain in the filling area,the filling and cleaning process of the hole rollers were analyzed,and the fillingcharacteristics of the sowing device under the conditions of different structures and parameters were obtained.The filling process of different structure seeding device was simulated,and the qualified rate of filling species in the hole was statistically analyzed.It shows that the qualified rate of the cross guide type chamber filling is%,and the filling rate of the sowing device with circular arc shaped hole sowing roller is 86%,and the filling performance of the hole roller is improved.All the achievements above provide the optimizing the structure parameters of the sowing device the theoretical basis.(4)According to the principle of Box-Behnken experiment design,the parameter optimization experiment of seeding device is carried out.Taking 3 structural parameters of seed chamber as experimental factors,we carried out the orthogonal regression test of seeding performance of three factors and three levels.The optimal combination of parameters are as follow: the radius of the transition arc of the crossing area is 42.8mm;the opening gap in diversion crossing area is 25 mm,and the vertical clearance between guide plates is 25 mm.With the best parameters above,the best working parameters were verified and the qualified rate of seeding reached 82.1%.The results showed that the optimized seeding chamber could effectively improve the seeding performance,and the seeding performance of the direct acting seeding device increased by 3.9%. |
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