| Hydroponic leafy vegetable planting is easy to achieve automatic regulation,real-time monitoring,annual planting,and can save planting space and improve economic benefits through three-dimensional cultivation.However,the planting density of hydroponic leafy vegetables is high.At present,the harvest is mainly artificial,and there are problems such as high labour intensity,time consumption and low efficiency.Compared with foreign countries,domestic hydroponic harvesting technology is immature and in the research and development stage.Therefore,leafy vegetable harvesting has become a bottleneck restricting the development of China’s leafy vegetable industry,and there is an urgent need to develop leafy vegetable harvesting machinery with low loss and high efficiency.This study takes hydroponic leafy vegetables as the research object,and studies the key components and equipment of mechanized harvesting of leafy vegetables.The specific research contents are as follows:(1)The effects of different knife types and cutting speeds on the cutting force of leafy stalks were studied.In this paper,the single-factor test and multi-factor orthogonal test were carried out on the knife type and cutting speed that affect the cutting of leafy stalks.The results show that the knife type and cutting speed have a significant impact on the cutting force of the stalk.When it is 12m/min,the cutting force of the stem is the smallest;by fitting the cutting curve of the stem,the fitting equation of the cutting process of the stem by different knife types is obtained,and the fitting accuracy is over 90%.Cutting force and cutting energy,the results show that the average cutting force and cutting energy of the oblique knife on the stem are the smallest.(2)The effects of different compression ratios and loading speeds on the flexural and compressive properties of leafy stems were studied.In this paper,compression and bending tests were carried out on the stems of three leafy vegetables,Qingyejianye,Qingcui and Qingqi.The results showed that with the increase of the compression ratio,the maximum compressive load first increased and then decreased,and the stem changed from the deformation stage to the rupture stage.From the inside to the outside;the compression ratio of different leafy stalks is different.Qingqi breaks at a compression ratio of 30%,and Qingyejianye and Qingcui stems break at a compression ratio of 35%;Qingchun,Qingqi and Qingyejianye’s average maximum elastic moduli of the leaves are 22.18 MPa,14.73 MPa,and19.50 MPa,respectively,and the flexural strengths are 18.22 k N.mm~2,32.45 k N.mm~2,and16.55 k N.mm~2,respectively.(3)The morphological characteristics of 13 varieties of leafy vegetables at harvest period were screened for the varieties suitable for mechanization.In this paper,the morphological indicators of 13 varieties of leafy vegetables at the mature stage were tested and analyzed.The results showed that: 49-19,Qingchun,Qingqi and Xilan cabbage had erect plant types,concentrated leaves,small leaf expansion angle,long internodes,suitable for mechanization reward.(4)Structure design and experiment of mechanized harvesting equipment for hydroponic leafy vegetables.In this paper,the key mechanisms of the hydroponic leafy mechanized harvesting equipment,including the cutting mechanism,the gathering support mechanism,the pushing mechanism and the conveying mechanism,are designed,and a prototype is built.The cutting qualification rate,cutting loss rate and conveying success rate are indicators.The working effect of the prototype was tested.The results showed that the height of the support rod,the position of the push rod and the cutting speed had a significant impact on the working performance of the harvest equipment.When the height of the support rod was-10 mm,the cutting speed was 0.5m/s,and the height of the push rod was at 50 mm,the cutting pass rate is 84.38%,the cutting loss rate of the whole machine is 22.48%,and the conveying success rate of the whole machine is 71.88%. |
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