Results of the Experimental Study on Grain Separation Using a Flat Oscillating Sieve with Zigzag-Shaped Hole Arrangement

The aim of the research is to increase the efficiency of preliminary and primary screening of grain heaps obtained after harvesting by combines. Achieving this goal will allow obtaining high-quality grain to meet both food needs and further use for obtaining seed material. The study presents the results of experimental research based on multifactor planning methodology in the form of a central composite design with star points, implemented in the STATISTICA 12 software package. Experimental tests were carried out on the Petkus Wutha K 294 A laboratory separator, which enabled simulation of operational conditions typical for industrial grain cleaning machines. The effects of specific feed rate (qb), oscillation frequency (n), and the angle of deviation of hole axes from the sieve axis (β) on separation efficiency were examined. It was found that the most influential factors are feed rate and the deviation angle. Increasing β from 0° to 10° resulted in an average efficiency growth of 8…16%. The best separation results (Y ≈ 80%) were achieved at qb = 800…1150 kg/m·h, n = 400…500 oscillations/min, and β ≈ 10°. The experiments confirmed the hypothesis that the original sieve design with zigzag-arranged oblong holes activates intralayer processes in both longitudinal and transverse directions, leading to process intensification and improved cleaning performance. The conclusions emphasize that intensification of intralayer processes on flat oscillating sieves is the key factor in improving separation efficiency. The zigzag arrangement of holes ensures a more uniform distribution of the grain layer, enhances impurity removal conditions, and reduces surface overloading. The experimental results are of practical importance for the improvement of grain cleaning machine designs and can be applied in the development of new sieve separators. The proposed technical solution combines simplicity of implementation with high efficiency, confirming its feasibility for industrial application.