Research On Key Technology Of Scallion Conveying Device For Scallion Harvester

As an important economic crop in China,green onion needs to go through four stages of planting,transplanting,field management and harvesting.The harvesting process is the most important,and the harvesting efficiency directly affects the final quality.Although China’s green onion planting area,total output and total export volume rank first in the world,China’s green onion harvesting machinery started late,and the harvesting method is mainly based on artificial harvesting and semi-robot harvesting,which greatly increases the operating cost.The economic benefits of planting green onions are reduced,which directly affects the enthusiasm of people to grow green onions.In view of this,based on the research status of domestic and foreign onion harvesting machinery and the research status of gripping and conveying technology,this paper designs a new type of symmetrical flexible clamping conveying device through field research and the actual situation of harvesting of green onion in China;It is guaranteed that the designed device can meet the operation requirements,and has been deeply studied from four aspects: physical and mechanical properties testing of green onion,theoretical design of key mechanisms,simulation analysis of key components and optimization of key parameters.The main research contents and research results are as follows:(1)The physico-mechanical properties of the onion during harvest were studied experimentally.The physical properties of green onion and its soil environment were studied by mathematical statistics method,and soil hardness,soil water content,soil bulk density,plant height,stem height,stem diameter,root depth,stem water content,and natural dispersion were obtained.The variation range and distribution law of physical indicators such as opening range and quality;the stalk mechanics test of green onion was carried out by electronic universal testing machine,and the relationship between load and displacement was obtained,and the pull-out force of the stalk of green onion was obtained by regression analysis.The variation of the crushing force with the increase of the stem diameter;the pull-up force test of the green onion under natural growth condition and the green onion after excavating the shovel was carried out by digital display force gauge It was found that the pull-out force of the green onion was significantly reduced after the excavation shovel was loosened.The design of the grip conveying device was to follow the design principle of first excavating and then pulling out,and the optimal loose soil position was obtained through the response surface test.(2)The overall design and key mechanism research of the onion harvester clamping conveyor was carried out.The clamping conveying device adopts a double belt symmetrical design,which mainly includes a driving mechanism,a clamping mechanism,a soil removing mechanism,a frame and a conveyor belt;the designed clamping mechanism can automatically adjust the clamping force according to the diameter of the onion stalk.The size of the conveyor belt and the onion stalks are always in close contact to ensure the continuity and reliability of the harvest;the structure of the crank mechanism is used to design the soil removal mechanism,and the kinematic theory analysis is carried out,the mechanism will be eccentric The continuous rotation of the wheel is transformed into the reciprocating jitter of the shaker rod.The regularity of the shaker rod beats the onion stalk to achieve the purpose of shaking the soil;the force and analysis of the conveyor belt are used to obtain the torque and speed of the hydraulic motor required by the drive mechanism.Suitable hydraulic motor;the key operating parameters of the clamping conveyor angle,the forward speed of the whole machine,the clamping conveying speed and the eccentric speed are analyzed,and the value range is determined.(3)Numerical simulation study was carried out on the key components of the stalk harvester clamping conveyor.The UG and ANSYS Workbench co-simulation analysis method is used to analyze the structural statics of the frame,and the stress cloud and deformation cloud diagram of the frame are obtained.After analysis,the strength of the frame meets the working requirements;the same method is used to stabilize the frame.Sex analysis,the first six natural frequencies of the rack are obtained.After comparison with external excitation,the external excitation does not cause the resonance of the frame to meet the stability requirements.The UG and ADAMS co-simulation method is used to move the soil removal mechanism.The simulation analysis shows that the displacement,velocity and acceleration of the point E of the maximum amplitude of the shaker are change with time,which is basically consistent with the kinematics analysis of the de-soiling mechanism,which further verifies the continuity and stability of the work of the de-soiling mechanism.(4)The experimental research on the holding conveyor of the onion harvester was carried out and the key operating parameters were optimized.According to the design principle of Box-Behnken test,the forward speed,clamping conveying speed and eccentric rotation speed of the whole machine are taken as the test factors,and the response surface optimization test is carried out with the loss rate of green onion and the evaluation index of soil content.The design is tested by Design-Expert software.Results The analysis of variance and significance,the analysis of single factor effect and the influence of interaction factors were analyzed.Finally,the optimal parameter combination was obtained through parameter optimization and comprehensive analysis: the forward speed of the whole machine was 0.4m/s,and the clamping conveying speed was 0.56.The m/s and eccentric wheel speed is 200r/min.The test results show that the loss rate is 3.61%,the soil content is 5.74%,and the work performance is good,which meets the working requirements.