Study On The Facilities Vegetable Seedlings Mechanized Precision Seeding Technology

Sowing quality, which was decided by the seedling planter used in facility agriculture, has a direct effect on the yield of vegetables, therefore, it is urgently required that we should develop the high-quality and steadily-running seedling planter in line with the development of modern facility agriculture. The facility seedling industry has been developing in our country for a few years and has been up to large-scale, however, seeding farms adopting the mechanized seedling and sowing are not so many and it is still more common to use the traditional seedling method. Because the present seedling planters often lead the following phenomena to occur, such as serious seedling repeating, severe seedling leaking, low-accuracy seedling location, unstable operation, and so on, which would bring about low-rate emergence, uneven germination, hard follow-up thinning work and increased cost of seedling, meanwhile, it would cost high to import the steady foreign seedling planter machinery and rare seedling farms could handle the high prices, which has limited the mechanized planting and seedling to popularize and apply, thus, it is crucial to develop stable and reliable seedling planting machines suitable for China’s national conditions to solve the above problems.This thesis, according to the design schemes, analyzes the seedling theory, tries to work on the prototype, tests the sample and finds the better parameter combination.According to the sowing process, a seed has three states: the vibrant state in a disc, and adsorbed process state and the suction motion with nozzle state. Based on the states, this thesis has analyzed the motion, described the vibration process, analyzed the forces done to the seeds during the absorption process, found the basic conditions meeting the suction movement with nozzle and concluded the parameter influencing the above-mentioned states through the theory analysis finally.The design of the prototype adopts the way of vacuum-vibration absorption seeding, which produces negative pressure by using vacuum generator, absorbs the seed by nozzle. Besides, it increases seeds liquidity through the vibration way in order to reduce the friction between the seeds, uses the precise stepper motor and synchronous belt to drive plugs in order to improve positioning accuracy of plug during seeding, redesigns the delivering seeds structure for the low accuracy problems by using telescopic way which would lead the seed tube down into the hole and make the seeds falls directly onto hole bottom, use the programmable controller to control seedling to improve the operation stability and, adopts air-blast dropping seeds to improve the dropping stability and clear needle role in the air channel.After the completion, the prototype has been used for chili seeding experiments at the national precision agricultural research basement. Through the theoretical analysis and the preliminary experimental research, this study has chosen the selection of the suction nozzle aperture, negative pressure value and vibration flow as factors to test the influences on the test of single seed rate, leakage sowing rates and replay rate. Meanwhile, this study has chosen three levels for each factor on the basis of parameter range in the preliminary experimental research and designed three-factor and three-level orthogonal test which would be counted referring to GB/T 6973-2005 single grain (precision) seedling planter machine test method. According to the poor analysis and variance analysis of statistical results, the influence degree that each factor works on the indexes has been sorted. After comprehensive consideration, this study has selected the best combination of factors level and has redone the seedling experiments, with the results as the single grain rate 93.63%, the empty rate 4.04% and the replay rate 2.33%.Through the theoretical analysis and test analysis, some conclusions have been made according to the design of the prototype.Although, there is still some insufficient about the prototype, with the application popularization and of the research deepening, precisely mechanized seedling and planting technology still could get improved greatly and have a broad and promising development.