Design and test of wind-sieve type cleaning device for cumin threshing machine

Cumin grains face significant challenges during cleaning, due mainly to their small particle size and similar external dimensions. Specialized cleaning devices are necessary to improve a high impurity content rate and low cleaning efficiency. In this study, a wind-screen cumin cleaning device was designed, according to the unique physical characteristics of cumin seeds and the working principles of existing cleaning devices. The key components of the cleaning device encompassed the structural and parameter design of the composite double-deck sieve, the cross-flow fan, and the wind-blocking and intercepting device. Gas-solid coupling simulation was utilized to ensure its effectiveness. The pressure distribution was examined in the scavenging flow field, the airflow velocity, and the solid-phase movement of scavenging materials. The device structure was verified after the simulation. The main influencing factors on the scavenging effect were determined as the wind speed, vibration frequency, and air inlet angle. The three-factor and three-level orthogonal test was conducted as the test factors with the loss rate and the evaluation index as the impurity rate. A quadratic polynomial response surface regression model was obtained to further investigate the relationship between the independent variables and the scavenging effect. The optimal working parameters were identified for the scavenging device, with a wind speed of 10.27 m/s, a vibration frequency of 4.07 Hz, and an inlet angle of 20.26°. A homemade test stand was utilized to validate the optimal parameters. The combination of working parameters was tested as well. The average loss rate and impurity rate after cumin seed cleaning were 3.40% and 5.28%, respectively. The theoretical prediction value was close to the test ones, indicating the high accuracy of a regression model. Furthermore, the composite double-deck sieve was carefully considered to ensure efficient cleaning while minimizing loss. The cross-flow fan and wind-blocking-intercepting device also contributed to the overall effectiveness of the cleaning device. In conclusion, the wind-screen cumin cleaning device can serve as an effective solution to the challenges during cleaning. The optimal working parameters can be expected to minimize the grain loss and impurity rates. The gas-solid coupling simulation was used to further validate the structure design. The findings can provide a strong reference for the practical application and effectiveness of the cleaning device.