Design And Performance Test Of A Single Axial Flow Threshing And Separating Device For Millet

Millet harvesting is an important part of millet production.At present,millet harvesting has a low level of mechanization.Threshing and separating equipment as the core part of harvesting machinery have many problems such as low removal rate and high loss rate during operation.In order to improve the performance of millet threshing and separating equipment and the quality of millet harvesting,according to millet harvesting agricultural machinery and agronomic requirements,a millet uniaxial flow threshing and separation device test bench was developed for experimental research.1)Taking the millet variety Longgu No.31 in Daqing area as the research object,measuring the biological characteristics of millet,it was found that the ear of the variety was spindle-shaped,and there were three branches on the cob to form the valley code structure.Both the grain code and the grain were spherical;A self-made comprehensive testing device for mechanical characteristic parameters was obtained to measure the static friction coefficient,rolling friction coefficient,sliding friction coefficient,and collision recovery coefficient of millet grains.A tensile regression test of grain yard stems was performed to obtain a linear regression equation of the stem diameter of the grain yard and the connection force of the spike axis.2)The model of grain ears and stalks is established by the bonding model in EDEM software;design and calculate the structure and parameters of the separation drum,concave plate,and cover guide plate,and use CAD / CAM technology to build a three-dimensional model of each component of the device and perform virtual assembly;The threshing and separation simulation test was carried out.As a result,the optimized drum form was a bar-tooth combination type,and the selection range of millet threshing and separation parameters was obtained.3)Millet threshing and separation test bench with control system and parameter acquisition system were designed.The frequency conversion control is used to realize the start-stop control of the test bench and the smooth adjustment of the working parameters;the data acquisition and switching control software developed on the MCGS configuration software platform is used to realize the test bench working parameter acquisition;and the wireless transmission technology is used to implement the stress monitoring of the threshing and separation process.4)The single-factor test was conducted with the drum rotation speed,feed amount,and threshing clearance as test factors,and the removal rate,millet agglomerates rate,residual rate,entrainment loss rate,and non-stripping loss rate as evaluation indicators.The parameter selection range of various factors and the law of stress change are obtained: as the drum speed increases,the stress value and the frequency of stress change increase;as the feeding amount increases,the stress value increases,and the frequency of stress change decreases;as the threshing gap increases,the stress value decreases Small,the frequency of stress changes increases.5)Three factors and three levels of orthogonal experiments were carried out with the drum rotation speed,feeding amount and threshing clearance as test factors,and the removal rate,valley code rate,residual rate,entrainment loss rate,and non-stripping loss rate as evaluation indicators.According to the results of SPSS range and variance analysis,the sequence of each factor affecting the separation performance is obtained;the optimal parameter combination of the separation device is the drum rotation speed of 950 r / min,the feeding amount of 2kg / s,and the threshing gap of 8mm.A verification test was conducted,and the results showed that the clean-up rate was 90.3%,the millet agglomerates rate was 8.93%,and the loss rate was 0.77%,which met the national standard millet harvest loss rate of less than 8%.