Design And Experimental Study On Key Components Of Leaf Vegetable Harvester

In the 14th Five Year Plan,it is clearly proposed to strengthen the support of agricultural science and technology and equipment and build smart agriculture.Vegetable industry is an indispensable part of smart agriculture.In the process of vegetable production,the harvesting process plays a connecting role in the total production process.Therefore,the leafy vegetable harvester is an important equipment to optimize the harvesting process and build smart agriculture.At present,most of the leafy vegetables harvesters developed in China have some problems,such as high damage rate and poor harvest quality.In order to break through the bottleneck of the development of leafy harvester,this paper has carried out in-depth research on the key parts of the harvester(cutting device,clamping and conveying device),the main work is as follows:(1)Taking Suzhou green as the research object,the geometric parameters(plant height,expansion,stem diameter,stem length)of Suzhou green were measured and statistically analyzed.The quasi-static cutting experiments of Suzhou green stalk were carried out by texture analyzer,and the data were analyzed.The results showed that the radial elastic modulus of the stalk was 1.03Mpa～1.96Mpa,the axial elastic modulus was 2.74Mpa～5.13Mpa,and the shear strength was 0.79Mpa～2.10Mpa.At the same time,the density of stem was measured by measuring cylinder and electronic scale,and the average density was 0.895g/cm~3.The above measurement and test data provide a reference for the design and parameter optimization of the key components of the leaf vegetable harvester,such as cutting device,clamping and conveying device.(2)Combined with the geometric parameters obtained from the experiment,the working principle of the cutting device is analyzed theoretically,the structure of each part of the cutting device is designed innovatively,and the 3D model is carried out by using Solid Works software;meanwhile,on the basis of the mechanical parameters of Suzhou Green stalk,the established 3D model of stem cutting is introduced into ANSYS Workbench/Ls-dyna to carry out dynamic simulation analysis,taking the machine forward speed and cutting speed as independent variables,the single factor simulation test is carried out,and the stress variation trend with forward speed and cutting speed is obtained.Based on the results of single factor test,the regression equation is established with a complete cutting time as the evaluation index,and the global optimization algorithm is used to optimize the cutting combination parameters with the shortest complete cutting time as the objective.The optimal cutting combination parameters are obtained as follows:forward speed 0.143m/s,cutting speed10m/s.Based on the optimal cutting combination parameters under the simulation conditions,it is proved that the selection of the initial cutting motor can meet the working needs of the harvester.The experimental results provide a theoretical basis for the selection of relevant parts of the cutting device and the optimization of working parameters.(3)Based on the measurement results of the geometric parameters of Suzhou Green,the theoretical design and component selection of the clamping conveying device are carried out,and its 3D model is carried out.A self-made single gripping conveying test bench,a multi-factor orthogonal test on the working and structural parameters of the gripping conveying device,a range analysis table is drawn,and a contour map of the interaction of influencing factors is drawn,the test results show that the damage rate of leafy vegetables is the lowest when the conveying speed is 0.2m/s,the inclination angle is 30°and the belt distance is 96mm.The above test results have a certain reference significance for the working and structural parameters of the clamping conveying device of the whole machine.(4)The processing and assembly of the prototype are completed in the factory;the accuracy of stem cutting simulation test results was verified by the prototype field test in the planting base,the results show that the simulation test is basically consistent with the field test;meanwhile multi factor orthogonal experiment was designed to explore the best combination of working parameters of machine forward speed,cutting speed and conveying speed.The results show that the forward speed has the greatest influence on the harvesting effect of the machine,followed by the conveying speed,and the cutting speed is the smallest.With the goal of low loss rate,the design-expert software is used to optimize the above three working parameters,and the optimal working parameters are obtained:the forward speed is 0.14m/s,the cutting speed is 10m/s,and the conveying speed is 0.23m/s.Finally,the machine performs multiple verification tests with this operating parameter.The test results show that the cut ends of the stems are smooth and smooth,without obvious peeling and burrs,the leafy vegetables stand upright and no obvious damage during the clamping and conveying process,the leafy vegetables after harvest have a low loss rate,and the appearance is good.