Research On The Motion Of Grain In 3-DOF Air-and-Screen Cleaning Device Virtual Prototype

This paper introduces the domestic and oversea researching progress and development of screening machine and cleaning device of the combine.The moving state of grain in cleaning device is determined by the movement of air and cleaning screen.The motion analysis of grain in cleaning device is the foundation of studying the cleaning ability of cleaning device.The conventional reciprocating vibrating screen is difficultly to separate the grain on the screen surface quickly,it is unbeneficial to the screening effect and efficiency.So the author comes up with the conception of 3-DOF air-and-screen cleaning device and the motion equation of screen,and designs the virtual prototype of this device.The force loaded on the grain by the screen and air flow is analyzed theoretically.The moving state of the grain in the virtual prototype decomposed along axial,normal and radial direction is researched.The positive,negative sliding indexes and the throwing index formulas about grain in the virtual prototype along the screen surface axial direction,the nonlinear vibration index formulas and motion law about grain along the screen surface normal direction,are deduced.Based on the theory of rigid-body collision with friction,the motion law of the grain along radial direction after impacting is obtained,and the formula of velocity variation along radial direction is gained during the pre and post-impact.Based on above theory analysis,the motion model of gain in the 3-DOF air-and-screen cleaning device virtual prototype is built by ADAMS.Analyzing and comparing with conventional reciprocating vibrating screen,the work parameters of 3-DOF air-and-screen cleaning virtual device are obtained.The parameters include: amplitude and frequency in the three directions,gradient of screen surface,direction angle of airflow,airflow velocity.Then the value ranges of all these parameters are determined and orthogonal experiment table is established in the basis of above,furthermore,the moving state of grain in the cleaning device is attained under the condition of various parameter combinations by simulation experiment.The primary-secondary factors affecting the moving state of grain in the three directions are figured out by analyzing the experimental results.The optimal work parameter scheme of the 3-DOF air-and-screen cleaning device virtual prototype,can separate the grain on the screen surface quickly,is obtained.Meanwhile the motion theory of grain in the 3-DOF air-and-screen cleaning device virtual prototype deduced above is verified.The researched 3-DOF air-and-screen cleaning device virtual prototype can make the grain on the screen surface quickly separate and uniformly distribute,it's beneficial to improve the utilization ratio of screen surface and cleaning efficiency.The work offers a reference and theory foundation for researching on the physical prototype of 3-DOF air-and-screen cleaning device,opens up a way for developing new cleaning device.However,as an independent system,the device is applied not only for the combined harvester but also many other fields.