Biomimetic Blades For Soil-rototilling And Stubble-breaking

Mole rat, as a typical soil-burrowing animal, is called as"living grab"because its high working efficiency during digging procedure. It can dig a long tunnel in length over 91m within one night. The claws of mole rat are better biomimetic prototypes for the soil cutting and excavating tools. The geometrical characteristics of the claws of mole rat can provide useful biologic information for the biomimetic cutting technology and design of soil cutting and excavating tools.Compared with the traditional moldboard plowing, rotary tillage has some advantages, such as, improvement of the working quality and efficiency, reduction of the working times required for machine in farmland, and therefore, lightening the compaction of soil, as a result, a good surroundings for seed growth can be developed. Single soil-rototilling or stubble-breaking machine is dominant in the world at present. The machine which can run these two kinds of work (soil-rototilling and stubble-breaking) need to be equipped with two rotors and two sets of blades, resulting in higher manufacturing and using cost.In order to promote machines in operating efficiency, in reducing of the cost of production and utilization, in combination of the soil-rototilling and stubble-breaking operation on one machine, soil-rototilling and stubble-breaking universal blades (universal blade for short) and biomimetic blades learning from the geometrical structure feature of the claws of mole rat (Scaptochirus moschatus) were designed taking a precondition for requiring for agricultural production. The power consumption and working quality of these two kinds of blades were examined through experiments.The solid model of the claws of the mole rat were manufactured using reverse engineering and rapid prototype technology. The effects of the geometrical structure and arrangement of the claw's toes on soil-cuting and soil-excavating performance were investigated in an indoor soil bin. It was found that, the horizontal resistance of solid model of claw of mole rat was decreased by 12.80% as compared with the contrast model, because of the effects of geometrical structure of the cutting edge. The soil-cutting resistance of the models with arrangement in arc was reduced as compared as the models with arrangement in straight line.The bending angle, bending radius, sliding cutting angle of frontal cutting edge and working width of single blade were taken as structure parameters through analysis of the motion parameters of blade during soil-rototilling and stubble-breaking and nine kinds of soil-rototilling and stubble-breaking universal blades were designed based on the L-type stubble-breaking blade and the wide soil-rototilling blade. Power consumption per unit working width was taken as the evaluation index. The optimal structure parameters of the universal blade were determined through the experiments of soil-rototilling and stubble-breaking in an indoor soil bin. It was demonstrated that the optimal combination of structure parameters were as a bend angle of 67°, a bending radius of 20 mm, a sliding cutting angle of frontal cutting edge of 12°and a working width of single blade of 60 mm. The tillage depth, rotary speed of the rotor and the working speed of the machine were taken as the experimental factors. The interaction of rotary speed and tillage depth on the power consumption was considered. Power consumption tests of a single universal blade were performed in the indoor soil bin to determine the influences of working parameters that mentioned above on power consumption in soil-rototilling and stubble-breaking operations. Soil bin tests indicated that the parameter that had significant influence on power consumption is the rotary speed followed by the tillage depth and the working speed had less influence. There was significantly interaction of rotary speed and tillage depth. Using regression design method, the regression equations describing the relations between power consumption and the above parameters were established. Then the working parameters were substituted in the regression equations, it was concluded that the siol-rototilling torque of single blade were 26.75 N·m～40.82 N·m and 45.97 N·m～56.01 N·m during stubble–breaking operations. The rototilling contrast test between the soil-rototilling and stubble-breaking universal blade and national standard rototilling blade and stubble-breaking contrast tests between the soil-rototilling and stubble-breaking universal blade and the common stubble-breaking blade were performed. The results showed that the power consumption per unit working width of the soil-rototilling and stubble-breaking universal blade was less than that of national standard rototilling blade, but more than that of the typical stubble-breaking blade. When they had the same width, the power consumption of soil-rototilling and stubble-breaking universal blade was less than the national standard rototilling blade and the typical stubble-breaking blade, which proved that it was reasonable and feasible to select the structure parameters of the soil-rototilling and stubble-breaking universal blade. Then, in order to examine the working quality, the soil-rototilling and stubble-breaking universal blades were mounted on a rototilling-stubble -breaking machine to perform soil-rototilling and stubble-breaking tests respectively. Field tests showed that the stability of the tillage depth was over 93%, soil-crushing rate, stubble coverage rate and stubble-breaking rate were 87.9%, 81.8%, 87.2% on average respectively, which meet the agrotechnical requirements, and realize the an integrated structure of soil-rototilling and stubble-breaking.The geometrical structure of the claws of mole rat was applied for designs of the frontal cutting surface of soil-rototilling and stubble-breaking universal blade. 9 kinds of biomimetic blades for soil-rototilling and stubble-breaking learning from the geometrical structure featrues of the claws of mole rat (biomimetic blade for short) were designed. The optimal biomimetic structure of biomimetic blade were determined through the experiments of soil-rototilling and stubble-breaking in the indoor soil bin and the optimal combination of biomimetic structure parameters were as follows: three arc concave teeth was arranged in a identical distance on the frontal cutting surface with a central angle of 60°. The three arc concave teeth on frontal cutting surface could change the contact area between soil and biomimetic blade during rotating proceedure. The contact area between the biomimetic blade and soil was decreased as compared with the soil-rototilling and stubble-breaking universal blade. The decrescent area mainly happens at outside edge of frontal cutting surface, and the penetration performance of biomimetic blade was enhanced by the geometrically structured cutting edge. The comparative experiments between the biomimetic blade and common universal blade were conducted. The tests showed that, as compared with universal blade, the torque of biomimetic blade was decreased by 3.91 % during soil-rototilling and 1.62 % during stubble-breaking. And the working quality of biomimetic blade met the requirements of the national standard.The power consumption of biomimetic blade, national standard rototilling blade and common stubble-breaking blade were tested using electric measurement method. The power consumption of unit area of soil-cutting was taken as test index since the ranges of soil-cutting were different. The results of field tests showed that the working quality of soil-rototilling of biomimetic blade were better than that of the national standard rototilling blade during the experiments of soil-rototilling. Also the power consumption of unit area of soil-cutting of biomimetic blade were less than that of the common stubble-breaking blade, even though the working quality of stubble-breaking of biomimetic blade was worse than that of the typical stubble-breaking blade. The working quality of biomimetic blade during stubble-breaking still met the requirement of national standard of China.The abrasive wear of biomimetic blade was tested on JMM testing machine which can effectively imitate field testing conditions. Abrasive wear test results showed that the abrasive wear loss of mass of the national standard rototilling blade was less than biomimetic blade, but the abrasive wear mass rate were closed. And, while the size wear loss of spinous cutting edge of biomimetic blade was largest, the average size reduction due to abrasive wear of biomimetic blade was less than the national standard rototilling blade, because of the cancave parts of the biomimetical teeth were protected by the tooth tips of cutting edge.The research work described about the biomimetic blades for soil-rototilling and stubble-breaking in this dissertation provides a reference for unity of soil-rototilling and stubble-breaking operations and improvement and optimization and design of key soil-cultivating parts of agricultural machines. The results have a practical application value.