| China’s pepper production and consumption level ranks first in the world,and the planting area accounts for 40%of the world’s pepper planting area.Precise sowing of pepper seeds is a key link in the mechanization of pepper production.Pepper seeds are light and thin as a whole and are flat and short kidney-shaped.Their non-circular and poor fluidity properties restrict the application of vegetable seeding machinery in pepper sowing.In view of the problems of complex structure,poor versatility and low qualification rate of the current vegetable seed precision metering device in pepper sowing,through the investigation of vegetable planting bases in Hunan,the theoretical analysis,mechanical design,control system design,Combining various methods such as trial production of experimental prototypes and bench tests,the mechanism analysis and experimental research of the mechanical precision seed metering device for pepper plug seedlings are carried out.The main research contents of the mechanical precision seed metering device for precision sowing are as follows:（1）Determination of physical properties of pepper seeds.Taking Xingshu wrinkled pepper,which is widely grown in Hunan area,as the research object,the physical properties of pepper seeds were studied,and their basic physical properties（triaxial size,thousand-grain weight）and related friction properties（sliding friction angle,static friction coefficient,natural angle of repose）were determined to provide a theoretical basis for the design and optimization of key components of the seed metering device.（2）Theoretical analysis and structural design of mechanical precision seed metering device for pepper plug seedlings.Based on the seeding principle of the magnetic return type seedling metering device,a mechanical precision seeding metering device for pepper plug seedlings was developed.The structure of its key components was studied and analyzed.Theoretical analysis and structural design of the reciprocating motion mechanism,the rotating mechanism and the seed-dropping mechanism are carried out,and the theoretical support for the prototype of the seed-metering device and the bench test are provided by analyzing the series of operations of seed-metering device filling,seeding,and seed-dropping.（3）Seed meter control system design.The hardware of each module of the control system of the seed metering device is selected.According to the seeding process of the seed metering device,the stm32 single-chip microcomputer is used as the microcontroller,and the hardware circuit including the power supply module and the execution part is designed and the program is designed.（4）Experimental research on the performance of the seed metering bench.Combined with the prototype,the performance test research of the mechanical precision seed metering device for pepper plug seedlings was carried out.Taking the single-grain qualification index,re-seeding index and missing-seeding index as the test indicators,the working speed of the crank motor,the angular speed of the rotating motor,the angular speed of the rotating motor,the Appropriate horizontal range for thousand kernel weight（seed weight）,crank diameter,and rotational inclination.According to the single factor test results,the interaction among the three factors of crank motor working speed,seed quantity and crank diameter was studied by Box-Behnken test method.The results show that when the diameter of the crank is30mm,the seed weight is 4 thousand-grain weight,and the working speed of the crank motor is 230 r·min-1,the performance of the seed metering device is the best,and the single-grain qualified index,replay index and missed seeding index are 92.30%,3.20%and 4.50%,and the verification test results were 91.04%,5.21%and 3.75%,respectively. |
