| Threshing and cleaning device is one of the most important parts of combine,its working performance have a major impact on combine's cleaning effect,power consumption,productivity and economic benefits.In view of the present research situation of threshing and cleaning device of rape combine,most of them are improved on the basis of the wheat and rice combine,with some empirical, not yet fully mature products be widely used.From the practical application point of view,dirt percentage and loss rate levels are difficult to achieve satisfactory results.Aim at the present research situation of threshing and cleaning device of rape combine,measured and analyzed the mechanical characteristic and aerodynamic characteristic of shedding materials, the wind velocity through top sieve surface in the cleaning room,the motion of shedding materials in airflow field and vibration sieve, structural optimization of vibration sieve as well as optimal combination of kinematical parameter of threshing and cleaning device by some measuring equipment, analysis cartography software, dynamic motion knowledges and indoor test, the main research contents and results was as follows:(1) Did quick formula fitting search for wind speed values which got from measure dot of top sieve surface through software lstopt,and obtained fitting equation of wind speed function of top sieve surface,then,utilize MATLAB to cartography for fitting equation found that velocity distribution on top sieve surface was high in the foreside,a little drop in the middle and gone up again in the tail,and vary of the fan rotate speed mainly affected the size of stream velocity of the top sieve surface and rarely affect on the distribution rule of airflow field.(2) Obtained material's motion mathematical model in airflow field and the range of cleaning index K's value when at a good cleaning effect condition through Kinematics and dynamics analysis for single material in airflow field and vibration sieve.(3) Utilized software ADAMS to establish virtual prototype model of vibration sieve slider-crank mechanism, regard the length of crank and different direction of motion of slider rod as design variable and took maximum the least transmission angle as design objective at the motion process of slider-crank mechanism,and made experimental design for virtual prototype model,came to a conclusion that the maximum least transmission angle was 84.7°when the length of crank is 25mm and direction of motion of slider rod is-10°.(4) Regarded loss rate and dirt percentage as main evaluating indicator,studied threshing drum rotate speed, centrifugal fan rotate speed and crank rotate speed's influence on riddle effects,and took the three kinematical parameter for single factor test and multi-factor orthogonal test, obtained the optimal combination of every kinematical parameters through analysis by synthesis was that centrifugal fan rotate speed is 1185r/min,crank rotate speed is 250r/min,threshing drum rotate speed is 700 r/min and centrifugal fan rotate speed is 1185r/min. |
