| In recent years,the forage utilization of peanut seedlings has gradually increased owing to their advantages,such as better nutrition,softer texture and lower price.It can be used as an important source of high protein roughage for many livestock and some aquatic organisms.Peanuts are often cultivated with agricultural plastic film to improve the yields in many main production areas of China,however,which results in the harvested peanut seedlings wrapped in residual film.Those residual film can seriously affect the digestive system functions of animals and reduce the forage utilization value of peanut seedlings.What’s more,there are some obvious problems during the forage utilizing process of peanut seedlings wrapped with residual film at present,for example,lower residual film removal rates and higher material loss rates.Therefore,it is an urgent issue and is of great practical significance to conduct research on residual film-seedling separation for improve the performance of peanut seedlings forage utilizing machines.Financed by the Central-level Non-profit Research Institutes Special Basic Research Expenses(Grant No.S202011 and No.S201918),this paper taken the main peanut varieties harvested seedlings that cultivated with agricultural plastic film of main production areas as the object of study.On the basis of research on the components and airflow selection characteristics of peanut seedlings shredded materials,and the separation idea of “seedling materials graded by vibrating sieve and residual film removed by two fans”,a kind of residual film-seedling separating device of which combined centrifugal fans and vibrating sieve was studied.The analysis,design and discrete element simulation of key parts and structural parameters of the device were carried out.After that,the designed peanut seedlings forage utilizing machine were taken as the experiment platform,the performance experiments and parameters optimization of residual film-seedling separating device were designed and conducted,and the rationality of such device and accuracy of the optimized regression models were verified.This paper can provides a valuable reference for the research and development of high efficiency and quality peanut seedlings forage utilizing machine and related equipment.The main research work and conclusions are as follows:(1)The representative harvested peanut seedlings that cultivated with agricultural plastic film were taken to conduct the test of components and physical characteristics of peanut seedlings shredded materials.The composition of peanut seedlings shredded materials were studied,the relationships between suspension velocity and moisture content of different peanut seedling shredded materials were studied and that of different varieties of peanut seedlings were compared and analyzed.The results showed that there were significant differences between the suspended velocity of peanut seedlings shredded materials and the residual film,and the regression model of each shredded material’s suspended velocity with its moisture content was different,but less affected by peanut varieties.(2)According to the test results of components and airflow selection characteristics of peanut seedlings shredded materials,and based on the separation idea of “seedling materials graded by vibrating sieve and residual film removed by two fans”,the overall structure of residual film-seedling separating device was determined,then the key parts of residual film-seedling separating device were studied and designed,the dynamic analysis of the movement and transportation of peanut seedlings shredded materials on double-layer vibrating sieve was carried out,and the operation mode of centrifugal fans and double-layer vibrating sieve was designed reasonably.(3)Based on DEM(discrete element method)and EDEM simulation software,the DEM simulation platform for the research of screening process of peanut seedling mixture on double-layer vibrating sieve was built,the classification and transport mechanism of peanut seedlings shredded stalks in the process of residual film-seedling separation were analyzed,the movement trajectory and change regulations of displacement and velocity in the direction of X、Y、Z axis of peanut seedlings stalks on double-layer vibrating screen were studied,and the single-factor simulation experiments were designed and conducted to simulate and analyze the influence of key operating parameters of double-layer vibrating screen on its screening performance.(4)The overall structure of the peanut seedlings forage utilizing machine was determined.According to the requirements on the forage utilization of harvested seedlings that cultivated with agricultural plastic film,the feasibility of the fan-sieve combined residual film-seedling separation technology scheme and working effects of the equipment were verified by using the designed peanut seedlings forage utilizing machine as the experiment platform.Combined with the above analysis,design and simulation results,the three-factor and three-horizontal Box-Behnken experiments were designed and carried out by taking the rotational speed of upper fans,lower fans and the frequency of vibrating sieve as experimental factors,residual film removal rate and materials loss rate as response values.The quadratic polynomial response surface regression models were established and optimized via the optimization modules of Design-Expert 8.0.6.The parameters optimization and validation test results presented that the residual film removal rate was 91.24% and the materials loss rate was 8.51%when the rotational speed of upper fans was 760r/min,the rotational speed of lower fans was 670r/min,and the frequency of vibrating sieve was 4Hz.The relative error between the validation test results and the predicted values of the models were less than 5%,which proved that the models were reliable and the residual film-seedling separation performance of such machine were improved. |
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