Design Of Rice Hill Direct Seeding Machine

In this paper,a rice hill direct seeding machine was designed according to the operation requirements in Jianghuai area.Firstly,the structure of the whole machine was designed.On this basis,the motor drive control system was designed to realize the function of speed linkage.Then the physical and mechanical characteristics of the "Nanjing 5055"rice bud seeds were determined,and the seed metering device was designed.The effects of related factors on seeding performance were explored through bench test.The optimal combination of parameters was obtained by processing and analyzing experimental data.Finally,the EDEM software was used to simulate the seeding process of the seed metering device,and the microscopic motion law of the seed during the seeding process was explored.The main research contents and conclusions were as follows:(1)According to agronomic requirements,a seeder with a working width of 240 cm was designed.The paddy field four-wheel drive chassis of the Jingguan ride type high-speed rice transplanter was used for providing power for the rice hill direct seeding machine.The rice hill direct seeding tool was connected with it by suspension,and the motor control drive system,machine transmission system and seeding adjustment mechanism were designed.The three-dimensional model was built and the prototype was manufactured by SolidWorks software.(2)The motor drive control system collected the pulse signal through the speed sensor mounted on the speed measuring wheel of the machine,then inputted it into the microcontroller.After calculating the inputted signal,the microcontroller outputted the PWM signal to drive the motor driver.The motor driver drove the DC motor to drive the seed metering wheel to rotate,realizing the function of speed linkage.Microcontroller is the core controller of the motor drive control system.The components of driving module,speed detection module,display module and power conversion module were selected and designed.At the same time,Keil software was used to write programs and built test circuit for testing.The test results showed that hardware selection,circuit wiring and software design of the motor drive control system met the expected requirements and can achieve the required functions.(3)Physical and mechanical characteristics of "Nanjing 5055" rice bud seeds widely planted in Jianghuai area were measured.Firstly,rice buds were prepared.Then the moisture content,thousand-grain weight,density,three-dimensional sizes,static friction coefficient,restitution coefficient and shear modulus of seeds were measured.It provided data support for the design of seed metering device and numerical calculation of seeding process.(4)The diameter of seed metering wheel,the number of groove holes,the shape of groove holes and the spiral angle of groove holes were designed.Single factor experiment was used to analyze the influence of the forward speed of the tool(speed of the seed metering wheel),the shape of the groove holes and the spiral angle of the groove hole on the seed metering performance(the qualified rate of the number of hill grains and the qualified rate of hill diameter).Then,the influencing factors were determined,and the orthogonal test was carried out with the qualified rate of the number of hill grains(3-8 grains)and the qualified rate of hill diameter(<60 mm)as the evaluation indexes.The influence order and significance of each factor on each evaluation index were obtained by range analysis and variance analysis.The optimum parameters were obtained by multi-index optimization analysis:the forward speed of the tool is 0.4 m/s(the speed of the metering wheel was 22.22 r/min),the shape of the groove holes is spoon-shaped,and the spiral angle of the groove holes is 20°.Under this parameter,the qualified rate of the number of hill grains was 95.62%,the qualified rate of hill diameter was 91.58%.The order of influence of each factor on seed metering performance:the forward speed of the tool had the greatest influence on seed metering performance,the shape of groove holes took the second place,and the spiral angle of groove holes had the least influence on seed metering performance.(5)The three-dimensional CAD model of rice bud seed was obtained by using three-dimensional laser scanner to scan "Nanjing 5055" seed.The number of filling balls in the particle model is 338.In the process of simulation,the triaxial velocity of a seed in the seeding process was analyzed,then the qualified rate of hill diameter and the qualified rate of the number of hill grains were taken as evaluation indexes,the qualified and unqualified hill were analyzed and compared,the mechanism of unqualified hill was explored.Finally,the test data of bench test and simulation test were compared.The errors of each evaluation index were within 5%.It was clear that the application of discrete element method to simulation analysis of seeding process has certain credibility.