Bionic Blade Of Corn Harvester For Leaving High Stubble And Its Cutting Mechanism

With conventional tillage and straw burning caused soil erosion increasing,declining soil fertility, increased air pollution haze, people gradually realized that theimportance and urgency of protecting arable land and environment. Straw as waste ordirectly burn up brings waste of resources and environmental pollution of soil, andmany suggestions to deal with straw were bring up. Meanwhile conservation tillage asan advanced farming technology mainly to protect arable land as the main objective,and to achieve high-yield crops and sustainable development, obtained more and morepeople’s attention, that important for straw back to field has been widely recognized bythe people, therefore more and more countries and regions are actively promotingconservation tillage. In addition to the connotation of conservation tillage for no-tillageand less-tillage, also includes straw back to field, it is widely believed straw caneffectively increase soil organic matter content, loose soil and can increase the capacityof the soil moisture conservation, and promote the crop yield. And the straw mulchingsolid earth could protect against wind, and effectively reduce soil water and winderosion phenomenon. However, crop stalks are also important sources of biomass, inthe case of non-renewable resources are depleted, and biomass energy obtained moreand more people’s attention. With the utilization technology of straw developed, moreand more utilization of straw will be used, but we cannot simply all be returning to thefield, especially in the Northeast, the cold weather is difficult to ensure effective stalkrotting increasing organic matter in field. Meanwhile, in order to meet conservationtillage on straw agronomic requirements, the paper advocates comprehensive utilizationof partial stalk, the other was put back to field. On this basis, the promotion of highstubble mulching conservation tillage mode is appropriate.It can be seen, when harvesting corn Northeast a more reasonable process is: whilethe corn harvest corn straw stubble cutting, leaving high stubble (stubble height of300~500mm) to meet conservation tillage straw requirements, while cutting down thestraw which would be bale collected, then utilization. So cutting the stalks must becompleted before the straw back to field and straw utilization operations. Currently, corn harvester mainly to smash all the corn stalks at harvest or no treatment, has notbeen able to stay high stubble operating models. Thus, this paper focused on the stubblecutting operating components of corn harvester, especially for the cutting blade carriedout using bionic design.（1）In a basis of the existing laboratory type4YZB-2corn combine harvester,removed the straw chopper off the device and designed the cutting stalk componentsunder snapping rolls. The cutting part uses the rotary disc cutting apparatus for cutting,the power source output shaft of the engine power, the power of the engine through thetransmission box and the power output shaft of the sprocket is transmitted to the cuttingdevice. Through self-made gripping device corn stalks were cut, results showed thatthe stubble cutting device reasonably designed to achieve high stubble designrequirements.（2）Atthesametimepartofthecuttingmechanismforcuttingwerebionicdesign.Nature, cutting phenomenon is very common, many animals or insects will tear or cutfood (biting) are all cutting areas, such as to endanger the silverfish eats holes, evenrodents mice and insects eat the leaf and stems. The plant-eating insects, especially thefamous locust plague of locusts is represented through a long evolutionary history ofits excellent eating mouthparts (chewing) can effectively feeding on stems and leavesof plants. The observation that when eating locusts can effectively cut off food.Therefore, mouthparts of locusts were observed, especially for the upper jaw with teethcut function. The locust’s palate samples observed under stereo microscope camera andtake photos with Matlab software for processing to extract the coordinates of the upperincisors, and the outer contour points by curve fitting software Origin, fitting into fivesegments curve. The fitting curve is the prototype of the bionic design cutting parts.（3）Based on the prototype linear and disc type bionic cut parts were designed,and traditional serrated blade as control, corn stalks were cut test.For linear bionic serrated blade, universal testing machine as the power to pullstraight serrated blade cutting fixed corn stalks, in the space of a Cartesian coordinatesystem in place at YOZ straight blade angle between the plane and the Z axis12degreesfixed in the fixture beams connected with universal testing machine, corn stalks in ahorizontal plane and fixed XOZ connected with the universal testing machine base inhomemade fixture. Straight blade speed of2mm/s cutting corn stalk from the bottomupward movement, in real time via computer software recorded the cutting force andthe displacement of saw blade, cutting test independently repeated12times.By contrast to conventional serrated blade, results showed bionic serrated blade significantly decrease the cutting force (P <0.05), using conventional serrated cuttingblade cutting corn stalks average force of71.78N, and the average cutting bionicserrated blade force of51.56N,28.17%cutting force was removed. Bionic serratedblade could reduce power consumption, compared with conventional serrated blade,bionic serrated blade cutting a stalk of corn consumed from10.27J reduced to8.95J.But for bionic serrated cutting blade, the cutting time is longer compared toconventional serrated blade, the average cutting time extended from37.52s to43.47s,17.83%extended cutting time.Through the slow motion video can be seen traditional serrated blade when cuttingcorn stalks are mainly part of the tooth tip hooked corn stalks, with the continuedpulling the blade gradually pulled straw after stripping off until cut off. Bionic serratedblade while cutting in addition to pull off the role mainly by sliding cut.（4）For disk bionic serrated blade, because it isn’t work using universal testingmachine to test, the author designed the corn stalk cutting test bench. The test rig drivenby an electric motor test disc blade for cutting corn stalk, the process of cutting bladecutting through the torque sensor to measure torque variation, by adjusting pulley gearratio change disc blade cutting speed, change of corn pulling velocity by continuouscurrent motor and measured the pull force by pulling the sensor, and data acquisitionand processing through dynamic signal acquisition and analysis system. Experimentalstudy of the circular saw blade cutting speed, corn stalks forward speed, and cuttingangle affecting the cutting force, cutting power, pulling force and cutting stalks of time.A full factorial experimental trials was conducted, each test was repeated three times,the test showed that the cutting time is not significantly different，the cutting torqueand the cutting power consumed have significant effects (P <0.05).Cutting speed is600rpm, cutting angle is75°, stalk pulling speed under1.3m/sconditions, bionic serrated blade and traditional serrated blade were used for cuttingcorn stalks comparative test, the test is repeated20times independently. The resultsshowed that the bionic serrated blade and traditional serrated blade can be achievedgeneral effective cutting, using traditional blade cutting corn stalks the mean cuttingtorque is1.691±0.226N·m, while the use of sharp teeth staggered double-sidedsharpening bionic serrated blade B cutting average cut corn stalks when torque is1.439±0.214N·m, relative to the traditional serrated blade cuts reduced14.89%.Traditionalblade cutting energy consumption of corn stalks is34.034±5.224J, use sharp teethstaggered double-sided sharpening bionic serrated blade B cutting corn stalkssignificantly reduce the energy consumption to27.741±6.181J,18.49%lower, and the cutting time is not significantly changed. While cutting through the high-speed camerato observe the process, the results showed that the debris generated by bionic serratedblade cutting corn stalk is less than traditional blade, which indicated the cutting planeis more flat.（5）Placetheserratedbladedisc bionicdevicetothecornharvest stubblecuttingmechanism, in the fall of2013at Jilin University, conducted a field test corn harvestingand cutting stalk tests. The test results showed that: Bionic serrated blade disc caneffectively cut corn stalks, no push over corn stalk phenomenon, as opposed to thetraditional serrated blade, with a stubble neat features. During the test no congestionphenomenon was found, no adverse effects on the quality of the harvest, stubble leavingparts confirmed the rational design of the original system does not have a negativeimpact on the harvest, and to meet the requirements of conservation tillage to remainhigh stubble. Field test results showed that the corn stalk stubble height of399.5±24.9mm, between300~500mm, with a pass rate of100%, due to the topography andnatural straw lodging affect, stalks cut ratio was93%.we try to solve the problem which come from actual production, namely, how toleave high stubble for corn harvester when harvesting corn, and designed the cuttingstalk components which was believed reasonableness. While the use of biomimeticapproach to the design of the bionic cut parts, cutting corn stalks tests showed bionicparts have reduced the cutting power consumption. Therefore, the research content ofthis paper are in terms of the promotion of conservation tillage, in addition to cuttingparts bionic design has important implications in terms of energy saving for the futuredesign of the cutting unit provides a reference.