Design And Experimental Study Of Gas Suction Needle Type Precision Seed-metering Device For Panax Notoginseng

Panax notoginseng is a valuable Chinese herbal medicine in China,and its cultivation is still mainly done by hand-on-demand.Panax notoginseng seeding mechanization is in its infancy,and the existing mechanical precision planter has serious problems in injury and has limited the development of the Panax notoginseng industry.In order to solve the problem of mechanical seeding machine injury,this paper designed a gas suction needle type Panax notoginseng precision metering device.The structure and basic parameters of the seed metering device were determined by consulting the literature in the early stage.The seed metering device was tested on the bench test bench.According to the test results,the seed meter was improved,the vibration condition was applied to the seed box in the filling process,and the vibration of the seed box was simulated by the discrete element method.The reliability of the simulation results is verified by a threefactor quadratic rotation orthogonal combination test.The main research contents are as follows:(1)Based on the mechanical and physical characteristics of the seeds of the Panax notoginseng and the agronomic planting requirements,design the key components of the seed metering device,and use the crank rocker without the quick return characteristic as the swinging mechanism of the seed metering device,and the cam by the mapping method.The contour curve is designed,and the internal flow field of different types of gas needles is simulated by FLUENT software,which provides a reference for selecting the optimal type of gas suction needle.(2)In order to verify the seeding performance of the gas suction needle type seed metering device,a single factor test is carried out on the seed metering speed,the suctioning negative pressure and the suction hole diameter respectively,and the optimal value range of the above factors is obtained.Through the orthogonal test of three factors and four levels,the qualified index,the missed broadcast index and the replay index are used as the indicators for testing the seeding performance,and the primary and secondary order of the influencing test factors are finally determined,followed by the suction negative pressure,the seeding speed,Suction hole diameter.The test results were processed and analyzed by Design-Expert8.0.6 software.The parameters were optimized.When the seed meter speed was 70r/min,the suction negative pressure was 1250 Pa,and the suction hole diameter was 4mm,the seeding was qualified.The qualified index is 90.7%,the missing index is 8.6%,and the multiple index is 0.7%.(3)In order to improve the filling performance of the seed metering device,vibration conditions are applied outside the seed box to cause a "boiling" phenomenon inside the population to facilitate seeding.Based on the discrete element method,the EDEM software was used to establish the Panax notoginseng model and the particle factory model.The vibrating state was simulated in the horizontal and vertical directions of the seed box,and the vibration frequency and vibration amplitude applied to the population in different directions were observed.According to the inter-species average normal stress variance of the simulation results,it is concluded that the application of vibration in the vertical direction is better for the dispersion of the population than for the horizontal direction,which is beneficial to improve the filling performance of the seed meter.(4)In order to verify the reliability of the simulation results,the seeding device was tested for performance.The vibration frequency,vibration amplitude and seed layer height were used as test factors,and the qualified index,missing index and multiple index were used as test indicators.The three-factor five-level quadratic rotation orthogonal combination test method was used to calculate the response surface by DesignExpert8.0.6 software.The regression mathematical model was established for the experimental factors and test indicators,and the influence of test factors on the test indicators was analyzed.The test results show that when the vibration frequency is 115 Hz,the vibration amplitude is 1.5-2mm,and when the seed layer height is 45-50 mm,the qualified index is greater than 93%,the missing index is less than 6%,and the multiple index is less than 1%.The test results were verified and the results obtained were basically consistent with the optimization results.The conclusions obtained can provide a theoretical basis and key parameters for the subsequent development of the gas suction needle type Panax notoginseng precision seeding machine.