Structural Design And Experimental Research Of Cyperus Esculentus Harvester

As an important oil crop,cyperus esculentus has gradually increased its planting area in China in recent years,which is of great significance to ensure the safety of edible oil in China.The fresh stems and leaves of cyperus esculentus at the growth stage can be used as excellent forage resources and have broad development prospects in animal feed processing.At present,the domestic special harvesting machinery for cyperus esculentus harvesting is still in the research and development stage.When cyperus esculentus is harvested,it is mainly crushed and returned to the field by straw returning machine,straw crusher and other working machines and tools,which not only wastes forage resources,but also makes the harvesting and screening operation of oil sedge harvester more difficult.It is of great significance to solve the problem of collecting and leaving the field of oil sedge during the harvest of cyperus esculentus and design a special harvester for cyperus esculentus,so as to promote the high-value utilization of cyperus esculentus and promote the whole process mechanized production of cyperus esculentus.Therefore,based on the study of the material characteristics of cyperus esculentus in the harvest period,according to the agronomic and operation requirements,this paper determines the design scheme of the whole cyperus esculentus harvester,and carries out the parameter design and motion analysis of key components;Using FLUENT-EDEM coupling simulation method,the best parameter combination under the working conditions of optimal pickup rate and crushing qualified rate of oil sedge harvester is obtained;Through the field test of the prototype,the operation performance of the machines and tools is evaluated to meet the quality requirements of cyperus esculentus harvesting.The main research contents and results are as follows:(1)The material characteristics of cyperus esculentus during harvest were studied.Taking the "Spanish round grain" variety popularized and planted in the experimental area as the research object,the physical characteristics,contact characteristics,accumulation characteristics,mechanical characteristics and suspension characteristics of cyperus esculentus during harvest were studied.Part of the test results are as follows: the density is 750 kg/m3,the moisture content is 43.25%,the stacking angle is 48.5°,the shear strength is 135 MPa,and the tensile strength is 105 MPa.The average suspension velocity of the upper section,the middle section and the lower section are 3.1 m/s,3.8 m/s and 4.7 m/s respectively.It provides a basis for the design parameters of crushing and picking up device,screw conveyor and fan throwing device of oil sedge harvester.(2)The motion analysis and parameter calculation of the key mechanism of the cyperus esculentus harvester were carried out.Based on the overall design scheme of the sedge harvester integrating crushing and picking up,screw conveying and fan throwing,the theoretical analysis and parameter calculation of the crushing and picking up device,screw conveying device and fan throwing device of the sedge harvester were determined.The minimum speed of the crushing and picking device is 1804 r/min,and the arrangement of crushing knives is a symmetrical double helix structure,etc.;the outer diameter of the blade of the screw conveying device is 310 mm,the pitch is 180 mm,etc.;the diameter of the impeller in the fan throwing device is determined.It is 500 mm,the fan speed is 2100 r/min,the size of the throwing channel is 250 mm × 250 mm,and the throwing height is 1.5 m,etc.(3)The transport law of cyperus esculentus material in cyperus esculentus harvester was studied.Using the FLUENT-EDEM coupling simulation method,the influence laws of the parameters of grinding knife shaft speed,feeding amount and grinding knife bending angle on the pick-up rate and grinding qualified rate are explored.The results show that the primary and secondary order of the influence of each factor on the pick-up rate and crushing qualified rate is the bending angle of the crushing knife,the feeding amount and the rotating speed of the crushing knife shaft;when the best parameter combination is the bending angle of the crushing knife 90°,the feeding amount 2.10 kg/s and the rotating speed of the crushing knife shaft 2100 r/min,the pick-up rate and crushing qualified rate of the oil sedge harvester are 91.05% and 86.40% respectively,which meet the design requirements.(4)The field operation test of cyperus esculentus harvester was carried out.Based on the optimal parameter combination,repeated tests were carried out,and the average pick-up rate of the cyperus esculentus harvester in the field operation was 89.34%,and the average crushing qualification rate was 82.44%.The relative errors are 1.88% and 4.58% respectively,which verifies the feasibility of the simulation test results.The cyperus esculentus harvester meets the operational quality requirements of NY/T 1004-2020 "Technical Specifications for Quality Evaluation of Straw Crushing and Returning Machines".