| Virtual prototyping technology, which is also called mechanical system dynamic simulation technology, was developed in 1980s. Adopting virtual prototyping technology in the process of product's developing, can not only decrease product development costs by saving capital and time, but also increase product's market competition with improved product quality. Thereby, studying the application of virtual prototyping technology in agricultural machinery performance design, by which actualize numeral development of agricultural machinery, can not only improve agricultural machinery design level, but also promote the development of agricultural mechanization. At the same time, it is useful to promote the development of agricultural mechanization discipline. Based on the relative theories and methods and appliance of virtual prototyping technology summarized, and the status and research issues of precision seeding technology at home and abroad generalized, the author implement the performance design and parameter optimization study of precision seeding metering device by virtual prototyping technology, and explore new method to decrease product development cost and improve product quality. Air-blowing vertical-rotor seed-metering device was investigated by methods of virtual prototyping simulation analysis and material prototype tests, and optimal parameters have been obtained. The major points the paper focuses on are as follows: 1. Introduced virtual prototyping technology in the design of seeding machine for the first time, to explore the application method of advanced CAD technology in the design of agriculture machinery. The technical line of virtual prototyping development based on Pro/E and ADAMS was proposed. The virtual prototype models of air-blowing vertical-rotor seed-metering device parts were constructed, and its dynamic simulation of was conducted. In order to analyze laws of motion of particulate seeds in seeding process, the author constructed the combined models with air-blowing vertical-rotor seed-metering device parts and seed granular particles by the combined analysis soft of distinct element method based on the boundary element of CAD models (DEMBCAD), and carried out the analysis and seeding process simulation of the united seed-metering device model. The DEMBCAD can study the interaction between the dynamics components of the seed-metering devices and seed granular particles, know the movement trend of the seeds, track the movement law of the tested seed, and analysis the seed-filling mechanism and the effects of design parameters on the performance of the seed-metering devices. The DEMBCAD can also study the influence of physical properties of the seeds on the performance of seed-metering device. The analysis and simulation results show that the internal friction coefficient of seeds has more effects. When the internal friction coefficient exceeds 0.5, miss index increase remarkably. 2. For the first time, the author investigated agricultural machines by uniform design method. Performance experiments of Air-blowing vertical-rotor seed-metering device was carried out, and mathematical models of the seeding performance of air-blowing vertical-rotor seed-metering device were established. The experiments in nature air state and in air-blowing states were studied under laboratory condition. According to the international measures based on the theoretical spacing, the performance indexes estimated in experiments include: quality of feed index, multiples index, and miss index and percent drop. Mathematical models of quality of feed index, precision, multiple index, miss index and drop index were put forward. Regress equations were set up, and optimal parameters were found out. Experiments nature air state showed that performances of air-blowing vertical-rotor seed-metering device were sensitive to the seed-filling include angle, the seed-clearing angle, and operating speed. The performances of theseed-metering device can be promoted by rational configure of the seed-filling include angle and the seed-clearing angle. The trend of quality of feed index and drop index are nearly the same, and the optimal points of them are in the same zone. Improve the drop index of seed-meters is the key technology to increase the performances of air-blowing vertical-rotor seed-metering device. The optimal parameters are seed-filling include angle by 46.35 degree and seed-clearing angle by 55 degree. In nature air state, with 46.35 degree seed-filling include angle and over 55 degree seed-clearing angle set, theatrical drops of approximately 100% were achieved in operating speed less than 6.0km/h. In air-blowing state, with 46 degree seed-filling include angle, over 55 degree seed-clearing angle and air press 1.4-1.8kpa set, theoretical drops of approximately 100% were achieved in operating speed over 8.0km/h. In air-blowing state, the seeding performance indexes are mainly influenced by air press and operating speed. The influence of seed-filling include angle and seed-clearing angle on seeding performance decrease greatly, and consequently, the seed-filling include angle and seed-clearing angle can be configure in bigger ranges to match the work in nature air and uneven field. The orientation of the air jet has no notable influence on the performance of the seeder, and can be arranged according to craftwork. Set up by uniform design, the mathematical models of the seeding performance of air-blowing vertical-rotor seed-metering device can open out e internal laws of the seeding process, and optimized performance parameters of the seed-metering device. The uniform design and experimental results can be referenced in development of other similar products. 3. Renovation of air-blowing vertical-rotor seed-metering device includes as follows: seed supplying tub, which replaces the seed baffle, can control the seed-filling include angle in nature air state. Combined seed cut board, which replaces the hair brush, is useful to decrease the broken index. Reformed seeding shell can meet the agricultural demand of 2-strip in 1 ridge sowing. 4. Movements of seeds were studied by high speed CCD video computer system. It was found out that the seeds in convolute zone flow in reverse clock orientation. In air state, there is a convolute zone in upper of seed-filling field. Seeds are bubbly in convolute zone, and come into a flow in reverse clock orientation. While the air press in 0~0.8 Kpa, seeds change into suspend state... |
PDF Full Text Request