Material Movement And Experimental Study Of Air-and-Screen Cleaning Unit For Combine Harvester

This dissertation briefly introduced the kinds of structural style of the combine harvester for cleaning unit, as well as the theory study and simulation analysis methods about the movement of the material in the air-and-screen cleaning unit in domestic and foreign at present.Through the movement analysis of the material in the airflow and on the seives, synthetically considered the function of the airflow and the seives to the material,then seeked the formula of the material moving in the cleaning unit.On the basia of this, analyzed the material motion state in the cleaning unit. On the basis of analyses over the collision theory, a motion mathematical model of the mixture on the vibration sieve is established with proper assumption.By analyzing the major factor effect the motion state and motion stability of grain the motion regularity of grain with different ejection intensity is founded. And then proceed from collision theory of the particle, set up speed formula of the material group, analysed material moving law and the theory of delamination on this basis.The subject researched about the theory of material vibration lamination and horizontal motion lamination. The material fluctuates loosely when it received the screen surface inspiring. the material moves along the screen surface to the front and motions relatively between the material when it received the horizontal controlling force in the screen surface . These all caused interspace between the material and the interspace unceasingly changed. As the result of the opportunity is bigger that the small grain filled in the interspace, the small grain gradually sinks and the big grain gradually moves on. This makes the material lamination gradually and it works to the material passing through the sieves.Then reseached about the theory of the material passing through the sieves.Used ADAMS, one of the virtual prototype softwares, to construct its virtual three-dimensional entity model and carried on a simulation and virtual test on it. Simulated out material movement orbit and movement situation between the groups of different layers on sieve surface, Found out some parameters which influence cleaning course the most through studying further, including the force of airflow, the amplitude and the vibration frequency of sieve, etc. This offered the basis for following real test.Finally on the basis of experimental platform of thresh,separate,cleaning,Simulation and control of DF-3, tested through the single factor of carrying on organization's parameters and working parameters in the experimental platform, looked for and verified the parameters which influence the cleaning course the most and the influence degree, and through the rhombic finding the best suitable parameter of rice cleaning.