Study on anti-blocking law of variable amplitude screening under multipoint feeding of materials

Abstract

The cleaning process in crop harvesting is crucial, with sieve vibration parameters significantly impacting cleaning quality. However, low load thresholds and high feed rates of sieve can cause material buildup and blockages. To address this challenge, the screening mechanism can be enhanced using the principle of variable amplitude. The anti-blocking screening process with variable amplitude is simulated under multi-point material feeding by Multi-Body Dynamics and Discrete Element Method, where the feed rate of the grain mixture, and the angle of the guide chute, are treated as variables. The study then analysed the average velocity of the particle groups on the screen surface, the material mass ratio, screening efficiency, and impurity content. The results indicated that as the guide chute angle increased, the screening time, decreased progressively, which suggested that variable amplitude can effectively enhance screening efficiency and mitigate material accumulation. More critically, variations in the feed rate, significantly impact screening performance, thereby changing both screening efficiency and anti-blocking capabilities. Based on these optimised parameters, a mathematical model was developed and validated experimentally. High-speed photography and image processing were used to analyse the material distribution on the screen surface, confirming the reliability of the amplitude adjustment mechanism. The findings demonstrate that amplitude screening offers substantial benefits in improving efficiency and reducing blockages. Ultimately, the model's R² value of 0.884 confirms its high reliability, and the consistency between the simulation and experimental results underscores the effectiveness and feasibility of the proposed amplitude screen method.