Development of pneumatic collecting machine of red jujube in dwarfing and closer cultivation

Abstract: Production practice has proved that dwarfing and closer planting will be the main mode of jujube planting in Xinjiang and even in the whole country in the future. Generally, the yield of the dwarfing and closer planting is two times that of the conventional planting, which can reach 15 000 kg/hm2. At present, however, few matching machines are available to match the dwarfing and closer planting cultivation pattern of red jujube. The dwarfing and closer planting mode of 4 m×1.5 m (row spacing×plant spacing) is basically adopted in Xinjiang, and the dwarfing and closer planting mode of 3 m×2 m is adopted in some areas. The planting pattern was in line with the climatic conditions in Xinjiang, optimizing the spatial position of plants, improving the land utilization rate, facilitating the management of jujube gardens, enhancing the utilization rate of light energy, and thus improving red jujube production. However, this mode will cause problems such as narrow working space, narrow row spacing harvesting congestion and so on. Therefore, in order to meet the requirement of mechanization of jujube harvesting in dwarfing and closer planting, aiming at the main problems of low efficiency of jujube harvesting, vulnerable jujube harvesting and difficult sorting of jujube impurities, a pneumatic method of jujube harvesting was put forward, and a pneumatic collecting machine of red jujube in dwarfing and closer cultivation was developed. The machine was mainly composed of diesel engine, fan, dial sorting device, suction chamber, air trap, suction pipe, transmission system, walking system and vibration separation screen. The air suction collecting method was adopted to reduce the rate of wounded red jujube. The dial sorting device was responsible for sorting the red jujube leaves and the branches, after collecting and separating the jujube mixture, the second screening of jujube, gravel and soil is realized in the process of vibration and swing of the vibration screen separating mechanism. The vibration separation screen was designed and analyzed, and the eccentricity of vibration separation screen is 60 mm, the crank speed ranged from 131.61 to 160.62 r/min. By using Design-Expert 10.0.3.1 software, according to the Box-Benhnken center combination design method, the forward speed, fan speed, crank speed were selected as the influencing factor, and collecting rate and impurity rate of red jujube were selected as the response value for three factors , three levels two sub-regression orthogonal test was design. The test results showed that the order of influence of the test influence factors on the collecting rate and impurity rate of red jujube was that fan speed > crank speed > forward speed; verification test results indicated that when the forward speed was 0.60 m/s, the fan speed was 3 080 r/min and the crank speed was 140 r/min, the collecting rate of red jujube was 96.41% and the impurity rate of red jujube was 1.54%. The relative error between the field test value and the theoretical optimization value was 1.71% and 3.40%, respectively, which were less than 5%. This study provides a reference for the mechanization of red jujube picking.