| China is one of the countries with the highest cotton planting and production in the world,and its production has maintained a leading position for many years.In recent years,due to the rapid growth of production and the shortage of labor force,mechanized harvesting of cotton has developed rapidly.However,there are some differences between mechanized picking and manual picking.Artificial picking can improve the picking rate of cotton by picking out impurities such as cotton stalk,cotton peach,cotton shell and three silks,while mechanized picking cannot meet these requirements.Therefore,the cotton picked by mechanization will contain more impurities,and the time period of mechanized picking is short.Some of them are picked at night,so the moisture content of the cotton after picking is higher,and the cleaning and processing of the cotton picked by machine will be more difficult.Therefore,based on the existing machinepicked cotton cleaning processing technology,equipment and process,a new machine-picked cotton cleaning processing device is designed.Through theoretical calculation,fluid simulation analysis and experimental verification,the device was optimized and improved,and a dynamic compensation test device was built.The impurity removal efficiency of the device was tested and analyzed.The main research contents are as follows:(1)Through the investigation of the southern region of Xinjiang,it is learned that in the process of cleaning and removing impurities of machine-picked cotton,most of the materials are transported at constant time and constant speed.This method can easily lead to power loss of the pipeline and cause pipeline blockage.In order to solve the problems of high energy consumption,easy blockage and low impurity removal efficiency,the cleaning and impurity removal conveying device of machine-harvested cotton was optimized.After optimization and improvement,these problems are effectively solved.The device can not only effectively avoid pipeline blockage,but also improve the impurity removal efficiency of machineharvested cotton and reduce energy consumption.(2)The physical properties of machine-picked cotton were measured and analyzed.It was concluded that there were many kinds of impurities in machine-picked cotton,such as cotton stalk,cotton shell,cotton leaf,immature cotton peach,plastic film and hair.At the same time,a test platform was built to determine the critical suspension speed of the material.In the actual conveying process of machine-picked cotton,considering that the physical characteristics of machine-picked cotton are different from other materials,it is necessary to set the velocity of the conveying airflow to 1.8-2 times of the suspension velocity.This can ensure that the machine picked cotton can maintain the suspension state during the conveying process and avoid clogging.So the air velocity is set to 18-22m/s range between the best;through theoretical analysis and calculation,the basic structural and dynamic parameters of the conveying system are determined.(3)Based on the investigation and test results,the power loss and conveying parameters of the conveying system are calculated and analyzed.The Fluent fluid dynamics software is used to simulate the flow field of different pipe curvatures of the conveying system,and the optimal pipe curvature radius,elbow type and related parameters are selected.Through Solidworks three-dimensional drawing software,a machineharvested cotton cleaning and impurity removal device was designed,and the parameters were adjusted to determine the rationality of the device design.The key mechanism is analyzed theoretically and the appropriate device is selected.(4)The orthogonal test was carried out on the test platform of the machine-picked cotton impurity removal power compensation device.The test results showed that the impurity removal efficiency was increased by 8.29% after the power compensation system was used.When the conveying wind speed is 20m/s,the rotation speed of the spike roller is 600r/min,and the grid gap is 16 mm,it is the optimal parameter combination.The data were analyzed by variance analysis.It was found that the inlet wind speed had a significant effect on the impurity removal efficiency,the speed of the spike roller had a significant effect on the impurity removal efficiency,and the grid gap had a significant effect on the impurity removal efficiency.Among the parameters affecting the impurity removal efficiency,the inlet wind speed has the greatest influence,followed by the speed of the spike roller,and finally the grid gap. |
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