| The technique of winter wheat mechanical root cutting came from high-yield producing practice, and it's an important compounding technique for winter wheat precision planting. CAE academician Yu Songlie and other scholars, who are from SDAU, found that deep cultivation not only cut original fibers, accelerated new roots to grow deeply and widely, but also increased the rate of effective tillers, accelerated spike to grow bigger, accelerated kernels of each spike to be more, prevented premature senility, and it did have a remarkable increase-yield effect. It is a requirement for popularizing root-cutting technique to study and empolder new model of root-cutting machine, it is a key to develop wheat root-cutting production mechanization as well. This thesis based on wheat root-cutting theory, took use of the method of combining farming machinery with agriculture theory, finished the design of multifunctional wheat root-cutting machine for the first time at home. Based on the dynamic analysis to the machine, studied the operating stability, handling capability, root-cutting quality and effect completely and systemically, which solved the key technique to wheat root-cutting mechanization. 1. According to the agriculture request of wheat root-cutting technique, the main structure of the wheat root-cutting machine was designed and studied. The main structure characteristics and innovation points as follows: 1) Adopted root-cutting shovels and blades as operating parts for the first time. In order to fit different wheat planting models, different assembled configuration with root-cutting shovels and knives were designed, and the root-cutting distance between two near rows can adjust at a range of 100~500mm freely. 2) Designed a flexibility depth-control and profile-modeling wheel framework creatively, the profile-modeling wheel follows the surface of the earth under the press of profile-modeling spring, ensuring a steady root-cutting depth. The root-cutting depth can adjust at the range of 50~250mm freely. 3) Designed the flexibility-squash wheel framework to squash the soil after cutting roots, the squash force can be adjusted by changing the working length of the spring. 4) Designed triangle tooth-shape surfaces between root-cutting shovel and machine frame, which ensured the enter-soil angle keep steady in work. 5) Adopted two sets of driving wheels: rubber wheel and iron wheel, the tread(distance between the two driving wheels) can freely adjust at a range of 350-800mm. 6) Designed a ±120°-free-turning joint for driving wheel and axle connected, keeping the root-cutting machine to turn and handle flexibly. 7) Designed the type-new clutch that assembled with texrope pulley together, which characteristically by small size, compacted structure, steadily transmission of power and a longer longevity. 8) Used the texrope transmission, chain and gear to transmit the power, which had a simple structure and lower cost. 2. Studied and designed the key root-cutting parts—root-cutting shovel and root-cutting blade for the first time. The root-cutting shovel's parameters have an important effect on root-cutting quality. Through analyzing the structural parameters, for the first time proposed three main root-cutting mechanisms, and tested the root-cutting quality and effect with different parameters, finally got the best structural parameters. The test shows: the root-cutting power of a shovel mainly lies on soil-cutting angle β0, the sharp degree of blade and wing-open angle 2γ. Smash-soil angle βhas an assistant effect for wheat cutting root. With the increase of the wing-open angle and the soil-smash angle, the quantity of roots being cut increased continuously, but soil turnover, wheat seedlings injured and irregular earth surface will be serious. The bigger entering soil angle αis, the more both quantity of roots being cut and wheat seedling injured are, while α=3~10°, there is no soil turnover and wheat seedlings injured. The soil deformation area, root-cutting quantity and wheat seedings injured increased while the root-cutting shovel's breadth B and root-cutting depth increased. The test shows that the reasonable root-cutting shovel parameters are: γ=45°, β=12°, β0 =18°, α=8.5°, B=8cm. The root-cutting blade is a new-type wheat root-cutting operation part, its figure character can express by 4 sizes: curve radius r, height H, the length to protrude L, blade's handle crosssection d×C. The distance between root-cutting knife and wheat seedling, s , androot-cutting depth, h , are two important factors which effect on the root-cutting quality. The test shows that the reasonable configuration parameters of root-cutting blade are: h=120~150mm, s=30~50mm 3. Researched entirely working stability and handling capability of the wheat root-cutting machine, which ensured the design quality. Through analysing the dynamics of the wheat root-cutting machine and soil mechanics, the mass requirement and the centroid requirement of wheat root-cutting machine going forward steady and keeping the root-cutting depth steady were given in theory, as well the computational formulas were given, which provided a new theoretical basis to design the machine. The theoretical analysis and tests showed that the mass of the machine at the range of 60~125kg, and the centroid location is 15~40mm in front of driving shaft. The moving velocity is another important factor that influences the working stability and handling capability of the machine. The test showed that the woking stability decreased while over speeding, meanwhile deteriorated the handling capability, injured a great deal of wheat seedling ; but lower productivity with lower speed. The proper moving velocity is about 2.8~3.0km/h. 4. Studied entirely root-cutting quality and effect with different models of root-cutting parts assembled, and got the perfect root-cutting compages. The compages of working parts is an important factor that influences the root-cutting quality and effect. According to the requirement of agriculture, three different root-cutting testing projects were designed: cutting root with shovels compages, cutting root with blades compages, cutting root with both shovels and blades compages. The results showed that: all three projects have remarkable root-cutting and product-increase effect. Generally speaking, the rate of root-cutting of shovels compages is 25.8%, the rate of root-cutting of blades compages is 31.6%, the rate of root-cutting of shovels & blades is 42.1%; the average soil bulk weight decrease by 3.81~6.5%, and the average soil moisture content increase by 0.3~0.7% because of improving the soil surface condation. The root-cutting operation have an effect of restrain first and promote later, after jointing the roots weight evidently beyond the contrast which did not cut roots, and the deeper roots is also more. The three root-cutting methods all have remarkable production-increase effect. Spike number decreased, grain number per spike and 1000-grain weight increased evidently, the average grain yield increased by 9.96~11.41%. As a matter of fact, the combine of shovels & blades has the best root-cutting effect, and also has the most remarkable production increase. It showed that the more roots being cut, the higher production increased.
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