Development of cone disc type shelling mechanism for peanut seeds

In China, the planting area of peanut is 5 million hm2 and the yield is 17 million kg. Seed shelling is an important part of peanut seed preparation before sowing, the quality of peanut seed after shelling affects the emergence, growth and yield of peanut. At present, peanut seed shelling is mainly based on the shape characteristics of peanut pods, mechanical actions such as kneading, extrusion and impact are used to crack and break the peanut pods to complete the shelling. However, the existing peanut shellers have some problems, such as low rate of shell removal, high rate of seed damage and poor adaptability to peanut varieties. In order to solve the above problems, a cone disc shelling mechanism for peanut seeds was designed. Taking Huayu 23 peanut as the experimental object, the EDEM software was used to simulate the shelling process of peanut pods, and the optimal structure parameters of the cone type shelling mechanism were obtained by simulation analysis and prototype testing. The best structural parameters of the shelling mechanism were obtained through simulation analysis and prototype test, that is, the inclination angle of the lower cone was 25°, and the inclination angle of the upper cone was 30°. In order to further reduce the damage rate of peanut seeds, the rubber spines were pasted on the shell surface of the upper and lower cones of the machine. The rotation speed of lower cone, the minimum shelling clearance and number of rubber bumps were taken as experimental factors, threshing rate and damage rate of peanut were taken as response values, single-factor test and Box-Behnken test were conducted. ANOVA was performed on the test results by Design-Expert 8.0.6 software, and the regression models of the threshing rate and the damage rate between the rotation speed of lower cone, the minimum shelling clearance, the number of rubber bumps were established. The optimal combination of the three factors were obtained by the dual objective optimization method, that was the rotation speed of lower cone 270 r/min, the number of rubber bumps within one squire meter 5 500 and the minimum shelling clearance was 11 mm，respectively, at this time, the highest predicted value of the threshing rate was 97.95%, and the lowest predicted value of the damage rate was 3.19%. The comparative experiment results showed that compared with the drum type sheller for peanut seeds, the threshing rate of the cone disc sheller without rubber spines was slightly higher and the damage rate was slightly lower. The threshing rate of the cone disc sheller with rubber spines was increased by 2.03 percentage points, and the damage rate was reduced by 0.67 percentage points..According to the fatigue damage analysis of rubber spines, after 90 hours of shelling operation, the rubber skin was seriously worn and the shelling quality was reduced, it should be replaced in time. The research results can provide reference for the development and improvement of peanut seeds sheller.