Parameter optimization and experiment of the negative pressure precision seed-metering device for wheat

In order to ensure the most reasonable distribution of wheat seeds in the field to improve seeding quality and uniformity,a set of negative pressure precision seed-metering device was designed,which shares a hollow shaft.Every seed-metering device can sow two rows of wheat.By the STAR-CCM+,the analysis of nephogram,vectogram and streamline graph showed that more ideal structural parameters of the seed-metering device are 0.5 mm width of the slit sucking seed(WSS),150-200 mm diameter of the seed-metering disc(DSD),2.0 mm axial depth of air chamber in the seed-metering disc(ADS),and arc-shaped cross-section shape of the ring groove sucking seed(CSGS).Single-factor test on the JPS-12 test-bed analyzed the influence of the CSGS,WSS,DSD,and ADS on the qualified index(Iq),multiple index(Imul),miss index(Imiss)and coefficient of variation of qualified seed spacing(CV).Through the orthogonal on the JPS-12 test-bed,it is found that the influence of vacuum negative pressure and seed-metering device shaft speed is significant on the Iq,Imiss and Imul.Based on these,the structural parameters of the seed-metering device were optimized.The DSD is 180 mm,the WSS is 0.7 mm,the ADS is 2.5 mm,and the CSGS is arc-shaped.The optimization seed-metering device was tested on the JPS-12 test-bed.The Iq is 86.66%,the Imiss is 5.09%,the Imul is 8.25%,and the CV is 24.50%.These testing results fully coincide with the standard JB/T 10293-2013 Specifications of single seed drill(precision drill).The seed-metering device meets fully the requirements for wheat precision seeding.

Optimized design of the pneumatic precision seed-metering device for carrots

The small size, light weight, irregular shape, and impurities that characterize seed groups increase clogging tendencies in the traditional seed-metering device thereby making it difficult to achieve high-speed precision seeding. A pneumatic seed-metering device with good seed-filling performance for carrot was designed in this study. By analyzing the movement state of seeds in the device under the theoretical condition, it was concluded that the minimum critical negative pressure value of air chamber was 0.32 kPa, which provided a theoretical basis for simulation and testing. ANSYS 17.0 Software was used to simulate the shape of the seeding plate hole. By comparing the pressure, air flow stability between the suction surface and the plug removal surface of the convection field, it was concluded that the conical hole was optimal. A bench verification test was conducted on the device. The average qualified rate, missing rate, and replaying rate were 81.48%, 4.07%, and 14.45%, respectively, which provided a strong reference for the design of carrot precision seed-metering device.

Design and test of an inside-filling pneumatic precision centralized seed-metering device for rapeseed

The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research confirmed that the inside-filling pneumatic precision centralized seed-metering device satisfied the agronomic requirements of rapeseed planting and can be a reference for the development of precision seed metering devices.

Design and experimental study of the control system for precision seed-metering device

The precision seeding technique has been developed at full speed along with the continuous development of new agricultural technologies,especially those concerning cultivated patterns.The seed-metering device is the key component of a precision seeder.A ground wheel is used to drive the seed-metering device of the conventional direct seeder.However,the wheel bears high resistance and easily slips.Moreover,the adjustment of the precision seeder’s seeding rate is more difficult.In order to solve these problems,a control system which could keep the rotational speed of the seed-metering device consistent with the seeder’s working speed for the precision seed-metering device was designed.The control system includes a Hall sensor,a single chip microcomputer system,a motor control module,a stepper motor and a display.The control system used a Hall sensor to measure the seeder’s working speed and employed a single chip microcomputer system to predict the rotational speed of seed-metering device.It would then determine the relationship between the seeder’s working speed and the rotational speed of the seed metering-device according to the seeder’s working state,distance between seeds and the requirement of sowing rate.The system could effectively reduce the influence of inhomogeneous sowing caused by the ground wheel’s slipping.The system was found to be reliable by the experiment.The seeding control system could also make the speed of the seed-metering device and seeder’s uniform,improving the uniformity of the amount of seeding,and achieving the goal of design.This new design provides a platform to solve problems of the seed-metering device and the seeder.

Study on multi-size seed-metering device for vertical plate soybean precision planter

Aiming to solve the problem of small range of the appropriately sowing seeds existing in a vertical disc seed-metering device,the planter plate series with four sizes were developed according to the variety and size distribution of all soybeans in China.The structure and working principle of the vertical disc soybean seed-metering device were detailed,and the influence of the diameter of soybean on the working performance of the seed-metering device was analyzed through the software EDEM virtual simulation,so as to achieve the goal of covering the soybean seeds with all sizes by the minimum planter plate series as well as to obtain the most appropriate operating speed of each planter plate by optimization.For the planter plates with the hole diameter of 7,9,12,16 mm,the appropriate size ranges of sowing seeds are 4.5-6.0,6.0-8.0,8.0-10.5,10.5-13.0 mm,respectively,and the appropriate operating speeds are 9,8,7,6 km/h,respectively.The results show that this planter plate series can meet the requirements of seeding with all sizes of soybeans at the range of the most appropriate operating speed.The study method can provide a reference for design and optimization of precision planters.

Design and experiment of pneumatic seed clearing mechanism for pin-hole tube wheat plot precision sowing device

For the problem that when wheat is sucked up by the air suction method,the seeds are aligned in a small area,making it difficult for the contact seed cleaning mechanism to clean the seeds.The mechanism of seed cleaning airflow on wheat seed was studied,the flow velocity distribution relationship of the jet section was defined,the mathematical model of the jet velocity of circular and plane sections was established,and the key factors that could have a significant influence on seed cleaning effect were explored.A non-contact positive pressure air flow seed cleaning method was proposed.After theoretical calculations,it is concluded that the core section lengths of the circular section jet and the inline jet are 24.8 mm and 28.8 mm,respectively.The clearing distance is set to 20 mm.Through the single-factor test,the best air tube nozzle shape was clarified as a vertical inline nozzle.The angle of seed cleaning,the air velocity of seed cleaning,and the negative supply pressure were selected as influencing factors,and the seed leakage index,seed reabsorption index,and seed qualification index as the evaluation indicators to conduct a 3-factor 5-horizontal rotation test.A mathematical regression model of influencing factors and evaluation indexes was established to analyze the influence of these factors and indexes.The optimal operation parameters were obtained as the seed cleaning Angle of 19°,the seed cleaning air velocity of 58 m/s,and the negative pressure of 8.5 kPa.Under the optimal parameters,the seed leakage suction index is 8.23%,the seed reabsorption index is 0.33%,and the seed qualification index is 91.44%,which meets the design requirements.

Design and experiment of an air-suction potato seed metering device

An air-suction potato seed metering device was designed to improve the performance of the large-size seed crops planting equipment and provide a solution for problems on the mechanical potato seeder,such as high multiple-seeding index,high missing-seeding index,low qualified index,and limited versatility.The main structure and operation parameters in terms of rotating speed of the device,seeds height and pickup vacuum pressure were determined by theoretical analysis.Two orthogonal tests,conventional tuber(the triaxial average diameter is about 38-57 mm)test and mini-tuber(the triaxial average diameter is about 12-36 mm)test,were conducted to analyze the influences of these factors on the quality of seeding.The multiple-seeding index,missing-seeding index and qualified index were chosen for evaluating the working performance.The results of conventional tuber test showed that,the multiple-seeding index was 1.1%,the missing-seeding index was 0.8%and the qualified index was 98.1%under conditions of the 30 r/min rotating speed,25 cm seeds height and 10 kPa pickup vacuum pressure.The results of mini-tuber test showed that the multiple-seeding index was 0.5%,the missing-seeding index was 0.6%and the qualified index was 98.9%under conditions of 35 r/min rotating speed,17 cm seeds height and 3.5 kPa pickup vacuum.The working performances of the device can meet the requirements of precision seeding.