Desgin And Experiment Of A Remote Controlled Self-propelled Plot Seeder For Rapeseed

The selection of high quality and high yielding crop varieties by breeding trials is one of the important ways to ensure food security in China.The growth characteristics of rapeseed and the agronomic requirements are combined for planting during rapeseed plot breeding trials,and research on a remote-controlled self-propelled plot seeder for rapeseed is carried out.An rapeseed plot seeder was developed with the following main research and conclusions:(1)The domestic and foreign development history and research status of plot seeders are systematically analyzed.The rapeseed plot seeder is developed,and its general structure,working process and main technical parameters are established and relevant parameter analysis is carried out.Rapeseed remote control self-propelled plot seeder mainly includes walking system and rapeseed pulse air-fed seeding system.The seeder is capable of sowing six rows simultaneously,with an operating width of1200 mm and a row spacing of 200 mm.It has the function of remote control selfpropelled and quick-disassembling type seed clearing;The power of the travel system is analyzed and the power required for the seeder is calculated to be 0.774 k W,and two3000 WS DC brushless motors are selected to meet the power requirement.The ultimate angle of decline of the seeder is obtained from the longitudinal stability analysis with the increase of the drag coefficient between the seeder tracks and the ground.When the drag coefficient is taken as 0.8,the ultimate decline angle of the seeder is 38°;Seeder ultimate downhill angle increases with increasing track ground length.When the track ground length is 550 mm,the ultimate downhill angle of the seeder is 30°.When the slope is less than 30°,the seeder is safe to drive.One-sided brake steering is chosen as the steering method of the seeder.The theoretical turning radius of the seeder increases with the increase of the center distance of the tracks on both sides.When the center distance of the tracks on both sides is 980 mm,the theoretical turning radius is 490 mm and the steering torque is 240.63 N·m.(2)The structure and parameters of key components of the rapeseed plot breeder seeder are designed and analyzed.Mainly includes:(1)The diameter of the seeding wheel is 30 mm,the thickness is 55 mm,the shape of the type hole is spherical,the diameter of the type hole is 3mm,a single row of type holes is evenly arranged on the cross section of the seeding wheel along the axis,the number of type holes is 6,and the center angle of adjacent type holes is 60°.It uses ABS material as a whole and is made by 3D printing.(2)The structure of the gas chamber is a cylindrical cavity with a wall thickness of 2mm,a chamber outlet diameter of 4mm,and a cross-sectional ratio less than 4.It is connected to the outlet of the air chamber by a seed guide tube with a conical disc-shaped seed delivery opening above it.(3)The incomplete gear has a modulus m of 2,a tooth number Z2 of 20,an index circle diameter d4 of 40 mm and a tooth thickness of 5 mm.(4)The main body of the pusher is a hollow cylinder with a diameter of 14 mm,which is open with a module of 2 and a tooth number of 7.A cylindrical tab is provided on each side of the end of the pusher to match the keyway opened on the housing of the pulse gas feeding mechanism,the diameter of the round end face of the front end of the pusher is 23 mm and the thickness is 7mm,and the working stroke of the pusher is 31.42 mm.(5)The sliding knife furrow opener is selected as the main body of the furrowing device of the rapeseed pulse air-feed seeding system,with the cutting edge angle of 22.5° and the angle of penetration 145°.(3)The mechanical analysis of the seed-metering device of the rapeseed pulse airfed seed discharger is carried out,and the analysis concluded that:(1)In the seed filling stage,when the angle between the lateral pressure and the friction force and the seed dispensing wheel speed are constant,the seed filling angle increases and then decreases with the increase of the angle between the support force and the positive half-axis of the x-axis;When the support force and the positive half-axis of the x-axis and the seed dispensing wheel speed are fixed values,the seeding angle increases and then decreases as the angle between the lateral pressure and the frictional force increases.When the support force and the positive half-axis of the x-axis and he angle between the lateral pressure and the friction force are fixed values,the seed filling angle decreases with the increase of seed dispensing wheel speed 1.The seed filling angle of the rapeseed pulse air-fed seed-metering device is obtained in the range of 57°～115°,and the minimum seed filling height of the seed-metering device is 15.58 mm.(2)In the seed protection stage,when the angle between the support force and the positive half-axis of the x-axis the seed-splitting wheel speed and the diameter of the seed-splitting wheel are fixed values,the combined force on the positive half-axis of the x-axis tends to decrease and then increase with the increase of the position angle of the rapeseed;The combined force on the negative half-axis of the x-axis tends to increase and then decrease with the increase of the position angle of the rapeseed.It is calculated that the seed guard stage and the rapeseed pulse air-fed seed-metering device can transport rapeseed steadily to the seed drop stage.(3)In the seeding stage,when the seeding position is certain,the rotational speed of the seeding wheel decreases with the increase of the angle between the support force and the positive half-axis of the x-axis in the seeding stage;When the seed-splitting wheel speed is certain,the larger the angle between the support force and the positive half-axis of x-axis the larger the rapeseed position angle in the seed-delivery stage.(4)In the aerodynamic acceleration stage,when the air chamber cross-section ratio is constant,the combined force on the rapeseed in the xaxis direction tends to increase and then decrease with the increase of the airflow incidence angle;When the airflow incidence angle is certain,the combined force on the rapeseed in the x-axis direction increases with the increase of the air chamber crosssection ratio.The values of the location angle of rapeseeds are 10°～30°.(4)A bench test of an impulse air-fed seed-metering device for rapeseed is conducted:(1)in which a single-factor test showed that the better values of each factor ranged from: The speed of the seeding wheel ranges from 40r/min to 70r/min,the air chamber cross-section ratio ranges from 2 to 4,and the airflow incidence angle ranges from 10° to 30°;Orthogonal test to obtain better parameter combinations: 55r/min of the seeding wheel speed,1/4 of the air chamber cross-sectional area ratio,and 30° of the airflow incidence angle.With this combination of parameters,the qualified index of rapeseed pulse air-fed seed-metering device is 90.74%,the multiple index is 3.70%and the missing seeding index is 5.56%.(2)A high-speed photography-based seed collision experiment with rapeseed was conducted,and the results were obtained as follows: The larger the air pressure,the higher the collision velocity of rapeseed and the higher the seed breakage rate of rapeseed.When the air pressure is less than 0.1MPa,the seed breakage rate is 0.(3)A verification test of the seed-metering device of rapeseed pulse air-fed seed discharger base on high-speed photography was carried out:after the rapeseed are pneumatically accelerated by the rapeseed pulse air-fed seedmetering device,the seed trajectory is approximated as a straight line and the seed speed is 1.40m/s.(5)Field trial of a remote-controlled self-propelled plot seeder for rapeseed:(1)Carried out the rapeseed remote-controlled self-propelled plot seeder through performance tests,the rapeseed remote-controlled self-plot seeder was able to complete the operational requirements of up and down ramps on an 18° ramp;The actual turning radius of the seeder was measured to be 955mm;the average straight row runout of the seeder was 0.16 m and the average offset was 0.53%.(2)Field trials of a remotecontrolled self-propelled plot seeder for rapeseed are conducted,mainly including field working condition measurement tests and field sowing tests,with the following results:the soil firmness of the test field is 3675.62 KPa and the soil moisture content is 19.4%;the average number of rapeseed seedlings is 11 and the average plant spacing was 95.54 mm within a 1 m interval.