Design And Experiment Of Pneumatic Central Cylinder Hill Drop Hybrid Rice Direct-seeder

Hybrid rice has the characteristics of strong tillering ability and high yield,It is the main variety of rice production in China.which has made an important contribution to ensuring food security in China.At present,hybrid rice cropping mainly adopts two planting ways of mechanical transplanting and artificial transplanting,and the level of rice-planting mechanization is low.Mechanized direct sowing of rice is a light simplified rice cultivation technology,which has the advantages of labor-saving,time-saving,labor,good ventilation,less pests and diseases,low tillering node and good growth in the later period.According to the growth characteristics of hybrid rice,a small amount of precision sowing is required.The existing mechanical seed metering device is mainly sui Tab for medium-seeding amount varieties.Pneumatic seed metering device has the characteristics of less damage to buds and strong adaptability to the shape and size of rice seeds,which is widely used.According to the characteristics of small amount of precision direct seeding for hybrid rice,a kind of pneumatic central cylinder hill drop hybrid rice direct-seeder was designed in this paper.It mainly consists of the transplanter power,two sets of pneumatic cylinder sowing devices,seed delivery pipeline,integrated fan,airflow pipeline,synchronous furrowing and ridging chassis,etc.Relevant research has been carried out with the core of"precision direct-seeding"and"pneumatic centralization".The main research achievements are as follows:(1)The technical requirements for suction performance of pneumatic metering device for hybrid rice were determined.According to the hybrid rice agronomic characteristics of a small amount direct seeding,1?3 seeds per suction group were qualified,0 seed was missed and more than 4 grains were over sucked.The design parameters of the device were determined.The seed metering performance of the pneumatic central cylinder metering device was studied under different rotational speeds,negative pressures and and positive pressures.(2)The relationship between vacuum degree,rotational speed of the cylinder,clearing distance and qualified rate was studied by using the seed metering tester,and the regression model and response surface graph of qualified rate,missed rate andover suction rate were established.The method of combining DEM with HSP was used to determine the process of separating and absorbing rice seeds by different types of churning devices.The thickness of 2 mm churning device was chosen.The qualified rate can reach more than 95%,which improves the metering performance of the cylinder seeding device.(3)Based on computational fluid dynamics(CFD),the different types of air distributors and different angles of seed delivery tubes were analyzed by finite element method(FEM);the distribution of air flow field in different areas of the cylinder chamber was studied,and the cloud charts of air velocity and pressure distribution between different suction holes were determined;the movement trajectoryof rice seeds in different angles of delivery tubes was studied by high-speed camera technology,the distribution structure of seed delivery tubes tube was optimized.To reduce the probability of collision between rice seed and tubes,the air velocity was optimized.For C(maximum angle tube)seed delivery tube,the optimum airflow velocity is about 16 m/s;For B(second angle)seed delivery tube,the optimum airflow velocity of seed-feeding tube is about 32 m/s.(4)The centralized and distributed sowing method was put forward,the coordinate distribution of rice in the seed ditch was investigated with the factors of different angle delivery tubes different air velocity and speed of direct seeder.The seed coordinate distribution of C-tube is more concentrated under 16-24 m/s airflow velocity,The seed coordinate distribution of B-tube is more concentrated under 24 m/s airflow velocity.The seed coordinate distribution of A(straight tube)is more concentrated under 24 m/s airflow velocity.(5)The pneumatic central cylinder hill drop hybrid rice direct-seeder for hybrid rice was developed successfully.Four field experiments were conducted from 2017 to 2018.The yields of hybrid rice Jingliangyou 1212 were 7107.9 kg/hm2,7774.05 kg/hm2 and7435.45 kg/hm~2 respectively.The yields of Yongyou 1538 were 7830 kg/hm2.The experimental results show that the pneumatic central cylinder hill drop hybrid rice direct-seeder for hybrid rice has reached the design goal and met the demand of hybrid rice production.