| As the major cotton producing area in China,Xinjiang generally adopts film-covered planting technique,which leads to cotton being easily mixed with foreign fibers such as residual film during the mechanized harvesting.The quality grade of cotton is severely reduced by the influence of residual film.In this study,a kind of ejection and distribute material type unginned cotton residual film electrostatic separator was designed,which was mainly composed of material opening and ejection device,power transmission system,material distribute device,electrostatic separation device and other components.The separation of unginned cotton and residual film was realized through the operation method of opening and projecting,uniform material distribution and electrostatic separation.The main research contents were as follows:(1)The material and charging characteristics of unginned cotton and residual film were studied.The quality and suspension speed of unginned cotton in different states were analyzed,according to the different forms of the unginned cotton after picking,transportation and accumulation.The results of the charging test showed that: Unginned cotton and residual film can be quickly charged after passing through the high-voltage electrostatic field of corona discharge in a free-settling manner.In the randomly material samples,the average charge of the residual film was-32.91 n C;the average charge of the unginned cotton without contact with the ground electrode was-3.54 n C,and the average charge of the unginned cotton contact with the ground electrode was 1.18 n C.The research on material characteristics provides basic data and design guidance for subsequent machine construction.(2)The material characteristics of the unginned cotton and the functional requirements of the separator were analyzed,and the design of the separator was proposed.The virtual prototype was modeled with the3 D software Solid Works,and the overall design scheme was determined through comparative analysis.(3)The key components such as the opening and ejection device,material distribute device and electrostatic separation device were analyzed and designed,and the relevant parameters were optimized,according to the design principles and technical requirements of the ejection and distribute material type electrostatic separation machine for unginned and residual film.The working state of the nailing roller was simulated and analyzed by using ANSYS Workbench.The results showed that the normal working speed of the nailing roller was less than the first-order critical speed of the simulation results.The ANSYS static analysis was carried out on the distribute material grid and the electrostatic separation frame,and the unreasonable parts of the preliminary design were rectified.After the improvement,the equivalent stress and the largest variable of the parts all met the design requirements.(4)The engineering prototype was built based on the above design analysis.Taking the residual film separation rate as the response index,the optimal parameter combination was determined through the response surface analysis of three factors and three levels,and a mathematical model was established.The test results show that the optimal parameter combination is corona electrode angle 25.3°,corona electrode distance 17.23 cm,and discharge power 5.25 W.Taking the leveling effect as the evaluation index,the optimal combination parameters of the leveling effect are determined as follows: the speed of the projecting roller is 965 r/min,the speed of the leveling roller is 257 r/min,and the leveling grid distance is 30 mm.The obtained parameters were set in the engineering prototype,and the evaluation results of the field operation showed that the separation efficiency of the residual film of the projectile homogeneous unginned cotton residual film electrostatic separator can reach up to 78.3%,which meets the design requirements and the actual processing requirements. |
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