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The soil-covering and press wheel are the main parts of the corn planter, and their performances are directly related to the growth and the output of the corn. The device with the functions of soil covering and soil compaction can improve the soil moisture content after planting and simplify the structure of machine. The squeeze-type coverer is a typical device with the functions of soil covering and soil compaction. But due to that the contact area is too small to bring the poor stability of soil-covering and soil-compacting during work process, the squeeze-type coverer is often used on no-till planter. A new type of soil-covering and soil-compacting device for corn planter was designed in this paper. The device was composed of 2 soil-covering-pressing wheels with cone-shaped structure, and realized the functions of soil-covering and soil-compacting depending on the extrusion force of soil produced by soil-covering-pressing wheel during planting. The main structure parameters of the soil-covering and soil-compacting device were determined through theoretical analysis and experiment of double-disk opener, which were mean diameter of 350 mm, width of the horizontal part of single soil-covering-pressing wheel of 20 mm, width of the inclined surface of single cover-press wheel of 70 mm, and the value range of horizontal interval of left and right soil-covering-pressing wheel of less than 29 mm. The leaning angle of soil-covering-pressing wheel was determined through theoretical analysis of soil-covering process based on the shape of soil furrows, which meant the leaning angle was about less than 20°. Based on the agronomic requirement of soil-compacting, the range of external load was about 609-790 N. Through analyzing, it was found that the external load, the horizontal interval between left and right soil-covering-pressing wheel and the leaning angle were the main influencing factors on the functions of soil-covering and soil-compacting of the device. Taking the 3 indices as the experimental factors using Design-Expert software, the Box-Benhnken experiments of 3 factors and 3 levels were conducted, and the results showed that the order of the influence of the factors on the soil compactness in the top 5 cm soil layer of the seed furrow from high to low was the external load, the horizontal interval between left and right soil-covering-pressing wheel and the leaning angle. The order of the influence of the factors on thickness of covering soil was the leaning angle, the load and the horizontal interval between left and right soil-covering-pressing wheel. The optimal parameter combination of the device was the external load of 900 N, the horizontal interval between left and right soil-covering-pressing wheel of 13 mm and the leaning angle of 16°. Verification testing indicated that the soil compactness in the top 5 cm soil layer of the seed furrow was (43.8±1.9) kPa, the coefficient of variation was 4.3%, and the thickness of covering soil was (32.9±2.3) mm with the coefficient of variation of 6.9%. The soil-covering and soil-compacting device designed in this paper has good performance of soil-covering, soil-compacting and working stability. This study can provide a reference for the design of planters. [ABSTRACT FROM AUTHOR]

Rice is the most important crop in China, which has the largest planting area, the highest per unit area yield and the most total output. The production scale of rice has important significance to the development of grain production safety. Solid ridge is important guarantee for irrigation and rice growth. It can improve the yield of grain crops and reduce the waste of water resources, which is conducive to the construction of standardized farmland in China. At present, the ridge are built still by manual labor in some regions. The ridge building by manual labor have some problems such as poor quality, long operation period, and repeated labor intensity. Ridging operation belongs to a part of tillage operation in the whole production process. With the development of paddy field mechanization, the paddy field machinery ridging technology has become the bottleneck problem for production. Paddy field mechanization ridging is constructed by agricultural machinery to meet the production requirements of rice irrigation and ridge technology. Some Chinese scientific research institutes and agricultural machinery enterprises have carried out researches and designed paddy field ridge machines. These machines take the soil on both sides through the plow or rotary blade and other parts, and compact soil to build ridge by double disc rolling, but they have shortcomings of heavy body, poor flexibility, high power consumption, and limits to the sampling position, which affect the follow-up planting and soil leveling operations. This kind of machine can not fully meet the actual production demands in China. In order to improve the quality and the efficiency of ridging operation in paddy field, and to reduce the labor intensity, the 1DSZ-350 type hanging unilateral rotary tillage compacting ridger was designed, in view of meeting the agronomic requirements of rice planting in the northeast region of China. The overall structure and working principle of the ridger were illustrated and analyzed. The structural design and the theoretical analysis were conducted for key components, such as partial traction hanging adaptive mechanism, rotary tillage ridging adjustable depth transmission assembly, rotary tillage soil- collecting roller assembly and compacting ridging circular assembly. To improve the working performance of ridger and to obtain the best operation parameters, the quadratic general rotary unitized design experiment was carried out with the forward speed and the rotational speed as the impact factors, and the average value of ridge density and the variation coefficient of ridge height as the response indices. Based on experimental data, a mathematical model was built by using the Design-expert 6.0.10 software, the experimental factors were optimized, and the best combination was achieved. Test results showed that the forward speed of the ridger was 1.33 km/h, the rotational speed was 525 r/min, and the average of ridge density was 2 160 kPa, the variation coefficient of ridge height was 4.01%. On the basis, the field test was carried out, and the test results showed that the ridger was characterized by its compact-sized reasonable structure and simple operation. And its ridge had good quality, which was solid and smooth and could meet the requirement of paddy field production. The research results in this paper can provide the theoretical basis and direction for the research of mechanical ridger and its key parts for paddy field. [ABSTRACT FROM AUTHOR]