Abstract
Abstract: In Northeast black soil region, people always use small power equipment as their main mode in agricultural production at present, and deep tillage and subsoiling operation area is less and less, leading to the problems of shallow soil, plough layer thickened, reducing the number of effective soil layers, soil structure becoming poor, water storage capacity and adversity resistance weakened. It seriously restricts the increase of corn yield. Constructing reasonable plowing mode is the main way to solve the problem of "shallow, compact and less" cropland in the dry farming area of Northeast China. Therefore, it is an effective way to prevent soil degradation and increase grain yield by changing tillage measures to construct reasonable plough layer. The deep straw returning to the field and the "straw belt tight intercropping and loosening" plowing mode are used to achieve the soil improvement by embedding the straw on the surface between the rows and the seedling zone. It also has the advantages of deep burial of straw and the pattern of inter-row subsoiling in the plough layer, which is an important mode for the construction of soil fertile plough layer. The pneumatic 1JH-2 style straw deep burying and returning machine is mainly composed of rack, drive system, stubble breaking device, pickup pulverizing device, conveying device, ditching device, soil covering device, repressing device, and so on. Pneumatic conveying device is arranged at the rear of pickup pulverizing device, and it is mainly composed of auger, blower, pipeline and discharging pipe. A ditching device is installed under the dragline and the discharge pipe. The soil covering device which is composed of 2 cladding plates and the repressing device are installed at the rear of the unloading pipeline. It can finish straw pickup, ditching, deep straw burial, soil covering, and so on. The pickup pulverizing device pulverized the stubble and crushed straw on the surface by high velocity rotation and threw it into the conveying device to realize the crushing and collection. The working processes can be carried out in one operation, such as breaking stubble, picking up straw to smash, opening trenches and crushing soil, deep loosening between rows, deep burial of straw, compacting, and so on. The conveying device, which is one of the key components, is mainly composed of fan blade, wind machine shell, conveying pipe, discharging pipe and screw conveyor. After crushing, the pickup crushing device throws the crushed straw into the screw conveyor, which pushes the straw to the fan as the conveying device working. Then, the straw is thrown to conveying pipe with high velocity revolution fan blade, and the straw goes through the conveying pipe and discharging pipe under a certain initial velocity of airflow. At last, the straw is fed into the straw deep burial ditch behind the ditching device from the fan lies in the left side of the machine. . The motion process of straw in pneumatic conveying system at different velocity was numerically simulated by using the dynamic effect model with computational fluid dynamics (DEM-CFD). The results show that the minimum velocity of straw is 5.39 m/s, the velocity at exit is 6.27 m/s, and the velocity of air flow is 2-28 m/s at the rotational velocity of 1 850 r/min. The field test shows that, when the operating velocity is 3 km/h, the ditching width is 400 mm, the amount of straw is 1.6 kg/m2, and the ditching depth is 270 mm, the straw buried rate is 94%, the pass rate is 94.2%, the soil breaking rate is about 95.4%, and the buried depth reaches 200 mm; the technical indicators of stable operation can meet the technical requirements of agricultural machinery. This machine can realize the combined operation of stubble and straw pulverization, deep burial of straw and deep loosening between lines. It can enhance soil porosity, improve soil moisture and enhance soil organic matter, which can create good soil environment conditions for dryland sowing in Northeast China.
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