Bionic Soil Press Roller With Convex Geometrical Structure

In agricultural production, pression of soil after sowing is an important procedure.However, there are two problems, higher resistance and heavy soil adhesion, exist inconventional press rollers, which seriously affect operational effectiveness of theconventional press rollers. The press rollers which were designed in this work reachthe purpose of adhesion and resistance reduction, which will be meaningful inagricultural production. The two problems are directly related to contact interfacebetween rollers’ surface and soil and the material of the rollers. In addition, the weightand the forward speed of the roller also have the repressive effect.Innovative ideas were used to improve the press roller in order to reduceadhesion and resistance against soil. The main improvement of the press roller wasdivided into two aspects, changing the Geometrical structure and the material of thesurface. The ideas of this work was learnt from the Geometrical structure of the headsurface of dung beetle, which is a bionic method. The Geometrical structure at thecontact interface was changed by applying the convex domes to the surface of thepress roller. In addition, the domes made of ultra high molecular weight polyethylene(UHMWPE) were fixed on the surface of the conventional press roller. Bionic pressrollers were based on the combination of the Geometrical structure and the material ofthe surface.On the basis of the Geometrically structured surface and material improvements,the method of experimental optimization design was used to arrange the experiments.Height-diameter ratio, lateral spacing, angular spacing and weight were consideredas the factors. Each factor had three levels. The orthogonal tableL9(34)was used toarrange the experiments for reducing the number of tests and for comprehensivelystudying all factors.By using ABAQUS, the work contained finite element analysis on the processes,which used9convex bionic press roller and3conventional press rollers with differentweights. The orthogonal experiments were designed in the actual size of press rollers,examinating the resistance of the press rollers and the subsidence of the soil. The simulation results showed that the resistance of the bionic press rollers is better thanthe conventional press rollers. At the same time, the weight significantly affects thevalue of the two factors. Through analyzing the shape of the resistance curves, thevariations of resistance were summarized: at the beginning of the experiments, muchresistance was found. After a while, the resistance became stable, fluctuating within asmall range. Compared to the conventional press rollers, the convex bionic pressrollers in resistance stably vibrated in certain interval. With the increase weights of therollers, the resistance curves tended to be smoother.On the basis of the finite element analysis, soil bin tests were run in two moisturecontents,20%db and28%db. The resistance, adhesion, the moisture content of thesoil and soil bulk density were examined. The analyses of range and variance were forthe resistance and adhesion against soil. When the moisture content was20%db, thedrag reduction rate was between2.62%and35.59%, the adhesion reduction rate wasbetween23.65%and33.97%; when the moisture content was28%db, the dragreduction rate was between6.59%and36.94%, the adhesion reduction rate wasbetween26.68%and35.13%.The optimal combination from soil bin tests was used in field tests. In field tests,Geometrically structured surface, forward speed and weight were used as factors to dothe comprehensive experiments. Three indicators, resistance, soil bulk density and therate of emergence, were examined. The results showed that the resistance wasincreased with the increase of weight; the resistance was decreased with the increaseof the forward speed. The convex bionic press roller could achieve the purpose ofreducing the resistance against soil. The drag reduction rate was between12.92%and38.29%; adding weight could increase soil compaction extent; increasing speeddecreases soil compaction extent; using convex bionic press rollers decrease soilcompaction extent.