Design And Experimental Research On Key Components Of Small Pneumatic Vegetable Precision Seeder

Chinese vegetable planting area and output rank first in the world,but the comprehensive vegetable mechanization level is only about 20%,and the development of various production links is uneven.Because vegetable seeds are small,light and easily damaged,sowing is more difficult.Up to now,the mechanization level of vegetable planting is less than 10%.The backward technology of precise vegetable seeding and lack of equipment have severely restricted the development of China vegetable industry.Due to the advantages of greenhouses in coping with climate and geographical environment,the planting area is continuously expanding.However,the small vegetable planters currently used in greenhouses have the problems of single model,low planting efficiency,and poor adaptability of operating modes.In view of the above reasons,this paper designs a small positive and negative pressure double-acting vegetable precision planter,and Key components have been tested and researched,aiming to develop high-efficiency,high-quality,and adaptable small-scale vegetable seeding equipment,so as to improve the level of mechanization of vegetable seeding in greenhouses in my country.The specific research content is as follows:(1)Aiming at the problems of universal air chambers and large wind pressure loss of the existing pneumatic multi-row seed metering device,a single-disc multi-row independent air-channel type positive and negative pressure precision seed metering device based on the airway disk structure was designed.Relying on negative pressure suction seed,positive pressure assisted seed drop and impurity removal,to solve the problem of vegetable seeds sticking to the plate.The innovatively designed airway plate structure has three negative pressure airways on the front and positive pressure airways on the back.On the one hand,it reduces wind pressure loss,and on the other hand,it ensures the independent sealing of the positive and negative pressure airways.The structure of key components is designed such as airway disk,seeding disk,power disk,etc.The dynamic analysis of the working process of seeding,active seeding and forced seeding of the seed metering device shows that the main factors affecting the performance of the seed metering device are: negative pressure value,seed metering disc speed and positive pressure value.(2)The software is used to simulate and analyze the positive and negative pressure flow field of the seed metering device.The simulation results verify the reasonable design of the airway disk structure,which can provide a stable positive and negative pressure during the working process of the seed metering device,and reduce the size of the wind pressure required for work.In order to verify the rationality of the design of the seed mixing device,a discrete element simulation analysis was carried out through the software on the accumulation state of the seed freely falling to the seed box and the movement law of the population under the action of the high-speed mixing device.A single factor test of the stirring speed was carried out,and a suitable stirring speed was selected.(3)The metering performance bench test was carried out on the developed single-disc multi-row independent airway positive and negative pressure seed metering device.Through single factor test,it is found that the performance of the seed metering device is better in the range of negative pressure value of 1～2k Pa,seeding disk rotation speed of 15～25r/min,and positive pressure value of 150～250Pa.At the same time,the influence law of each influencing factor on the performance of the seed metering device was obtained,and it was found that the performance of the outer ring of the seed metering disk was slightly lower than that of the inner ring.In order to explore the influence of the interaction of various influencing factors on the seeding performance,a two-rotation orthogonal combination experiment was carried out.Obtained the parameter combination when the performance of the seed metering device is the best.The order of the primary and secondary effects on the missed seed index,replay index and qualified index is negative pressure value,seeding disk rotation speed,and positive pressure value.The seeding discs with different apertures were selected,and the variety adaptability test was carried out on the designed seeder.The missed seeding index of the three-circle seeding holes were all less than 3%,the replay index was less than 3%,and the pass index was greater than 95%,indicating The seed metering device has good variety adaptability.(4)Design and reasonable layout of other key components such as ditching and seeding device,suppression and sowing depth adjustment mechanism,completed prototype production and conducted field trials.Mainly inspect the index of planting plant spacing,planting depth and planting row spacing in the actual operation process.Through the analysis and investigation of field experiments,the indicators of the small pneumatic vegetable precision planter designed are better than the national standards,can meet the requirements of vegetable planting operations,and the planting mode is adaptable.