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In recent years, our government prohibit the burning of straw. Therefore, there are too many straws covered on fields which we have to deal with. The reserch proves that returning straw can not only refrain the environment pollution and traffic problem from burning of straw, but also improve soil fertility to reduce fertilizing amount. At the same time, the amount of middle and large power tractors(more than 70 hp) is increasing in south of china, but the quantity of agricultural machines which can match tractors is very limited. In that case, we should design one kind of machine which can mate big power tractors and can work in south fields as soon as possible.In this paper, the machine includes 8 seeding rows and 7 fertilizing rows, and it’s working breadth is 1.75m. Main parts of this machine include cardan joint, three point linkage, rotary till and returning straw part, seeding and fertilizing part, press wheel part. The machine can finish several procedures one time such as returning, seeding, fertilizing and pressing. Total power consumption of the machine is less than 25kw.In this paper, three point linkage system was simplified to two relative four bar mechanisms. Depend on linear programming theory and matrix theory, one mathematical model was established and optimized. The optimized three point linkage could keep the machine and tractor in coordination whether in working condition or in lifting condition, at the same time, it could save the material consumption by 14.7%.In this papar, power transmission line was optimized and transmission ratio was arranged reasonably. One type of square-tooth clutch was designed which could connect and cut the transmission line. In hence, the speed of seeding and fertilizing will meet with tractor’s speed. Compare to conditional fertilizer drills, working stability and uniformity of this machine were both increased.In this paper, when the blade shaft roll revolve and it’s speed is 240r/min, this machine could achieve the optimization level. The blade block arrangement was optimized, therefore, the power consumption of machine was descend, traffic ability of the machine were enhanced without grass and soil, and the service life of transmission parts would be increased because of less vibration. Blade shaft was optimized by linear programming theory, the section area of blade shaft was reduced by 21.6%.Fields test result show that the working quality of this machine was very good because of it’s excellent working stability and traffic ability. The key parameters of the machine could reach national standard, it could be popularized as a new kind of agricultural machine for environment protection.
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