Design And Test Of Rasp-bar Thresh For Maize

China is a big country of corn planting,and the planting area and yield of corn are the second in the world,so the demand for corn seeds is huge.In the process of corn seed processing,the most important is corn seed ear threshing,and all corn seed companies use machinery to thresh,so the quality of corn seed depends on the performance of the thresher.In order to further reduce the threshing loss of corn seeds,it is of great significance to deeply study the structure parameter optimization of the strip-type corn seed thresher.In this paper,through a series of methods such as mechanical test,structural design,response surface optimization test and so on,the structure parameters of a grain stalk type maize seed thresher are formed,the rate of threshing and breaking of maize seed ear is reduced,and the expected goal is achieved.The main research contents are as follows:(1)The experiment on the geometrical and mechanical properties of corn seeds shows that the physical properties of corn seeds are related to threshing.The experimental results show that the statistical results of the average grain size of corn seed from yayu 988 chengdan 30(27% of moisture content)are as follows: the length is 12.1mm,the width is 7.9mm and the thickness is 4.0mm,the probability distribution of triaxial size roughly shows the trend of normal distribution.The mean value of grain weight is directly proportional to water content.For corn with the same moisture content,the mean value of kernel weight of corn ear was > in the upper part and > in the middle part.(2)The experiment on the geometrical and mechanical properties of corn seeds shows that the physical properties of corn seeds are related to threshing.The results showed that both ends of corn ear were easy to take off,and the big end was easier to fall off than the small end.No matter which way of threshing force is adopted,the force required for threshing increases obviously with the number of supporting rows or grain number increasing.In the same situation,the degree of threshing difficulty: pressure threshing > laterally curved threshing > longitudinally curved threshing.Corn should be fed in a certain direction when threshing.First,the longitudinal bending force of grains is adopted to thresh,and some grains are removed,so as to reduce the number of supports and damage of grains and improve efficiency.(3)According to the above test results and related theories of agricultural machinery manual,the key components of the strike-stalk corn seed threshing device were designed,checked and calculated,and the prototype was tested.In this paper,a small-sized roller with diameter of 300 mm is adopted,and the small-diameter roller and high speed are favorable for grain separation.The length of the roller is 443 mm,and the structure is small and light,select the D-type striated bar teeth,the height is 13 0.5mm,and the mounting Angle is 23.The drum power P is 1.12 kw,Select the grid concave plate with the best separation effect,the arc length L of the concave plate is 300 mm,and the Angle Angle of the concave plate is 150,The inlet clearance is 45 mm and the clearance ratio is between 2 and 4.The clearance can be adjusted and the cleaning device is designed according to the size of feeding roller.(4)The single-factor and response surface optimization threshing test was carried out based on the grain stalk type corn seed threshing device.The results showed that the influence of various factors on maize threshing was > threshing rate > threshing clearance,Optimum threshing parameters of grain-stalk maize seed thresher show Threshing speed is 16.3m/s,water content is 18.42%,cylinder-concave clearance is 14 mm.Through the repeated validation test,it is concluded that the grain rate is 0.15% and the crushing rate is 0.85%,which provides a reference for the optimization and improvement of the stripper corn seed thresher.