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12Optimization of Combine Harvesting, Threshing, and Separating Systems for Reducing Corn LossRoohollah Mohammad Sanabadi Aziz , Sherwin Amini1. Research Instructor, Jihad Institute of Engineering (Located at 16km of Old Road Karaj, Tehran, Iran.2. MS Student in Mechanization Engineering, KhouzestanRamin Agriculture and Natural ResourcesUniversity, Khouzestan, Iran.Corresponding Author email: rohollahmohammadyahoo.comABSTRACT: Harvesting corn with a combine harvester leads to a certain degree of loss and thus reduces profits; although this loss cannot be fully eliminated, it can be controlled to areasonable degree. Preparing the combine for harvesting corn is a process involving the replacement of the harvest head and the concave and also the placement of cover plates on the threshing drum. A major obstacle in harvesting corn is the prevention of grain loss, which mostly occurs during the harvesting process at the combine head (when separating corn cobs from the stalks) and at the threshing drum and the concave (because of the corncobs breaking). The present research was conducted in a 400 acres farm property of the Seed and Plant Improvement Institute, Maize and Forage Crops Research Department, with prerequisites being a threshing drum speed of 750rpm and a crop moisture content of 11.6% on dry basis. The crop yielded and the amount of grain loss measured indicated that, when conventional heads exerting vertical force for separating the stalks are used, the degree of grain loss during harvesting becomes excessive; these heads cause a great amount of crop loss. Results of the present study were manifested on the combine cutter bars; therefore, for reducing harvest loss occurring at the combine header, headers made in Iran should be significantly modified. The first step taken in this respect was to design and implement necessary modifications to the two main parts of the machine, i.e. the “corn head” and the “feeder unit”.3Keywords: Corn Combine, Reducing Harvest Loss, Combine Header Modification, Threshing Drum and Concave, Feeder UnitINTRODUCTIONThe increasing population of the world is faced withshortageof food and thus needs to expand its production of high yielding crops such as corn in order to overcome it. MATERIALS AND METHODSThis project pursued to modify and optimize combine header systems and to achieve minimum grain loss in the production of corn; therefore, the first step was to purchase a combine corn head in order to study and analyze its systems. The source of corn loss occurring at the header was then identified along with other types of loss occurring at the system so as to identify their contributing mechanisms while taking all things into consideration and to then prepare for the standard testing and evaluation of the existing header. The next stage was to examine combine header operation mechanisms and to modify them according to the demonstrated causes of loss occurring in the combine for minimizing purposes. The final step was to conduct a trial run of the modified combine header on the farm so as to examine its degree of grain loss post modification and to compare it against its previous state.Examining combine headerThe examined system was a 4-rowcorn head that could be installed on John Deere 955 Combine Harvester. This head is designed to separate corncobs from their stalk and to then feed them to the feeder unit. This head has4 rows set at a fixed 75 cm distances of one another. The main parts of the system are:a) The Frameb) The Power transmission systemc) The Harvester (corn cutter)d) Grain conveyorCorn Head Technical Specificatio4ns: Required power: 45 hpInputrotation: 600rpmNumberofrows: 4Harvest rate: 4 5acres per 8 hours Weight: 1000 kgLength: 320 cmWidth: 280 cmHeight: 130 cmFigure 1. Overview of the corn headDesigning and proposing a proper mechanismAt this stage of the project, combine head mechanisms directly in contact with the crop and causing corn loss were first examined; then, based on the envisioned mechanisms, necessary modifications were made taking into account the functioning of the examined head components.Examining the combine headers feeder unit mechanismAs the combine harvester rides along the farm, the crop is fed to the feeder unit that then separates the cobs from their stalks. The feeder unit is responsible for the separating process; the movable parts of this unit derive their power from the mechanisms embedded gearbox. The parts enabling the separating and feeding of the corncobs are as below:6Figure 2. Feeder unit mechanismU-shapedframeCutterbarsChain conveyor mechanis7m Chain tightener spring mechanism SprocketStrawwalkerGearboxFeeder mechanism (of existing combine headers)The feeder unit parts can be divided into two general categories of fixed parts and movable parts. The fixed parts include the U-shaped frame, the chain tightener spring, the cutter bars and the straw walker. The movable parts include the chain, the roller chain and the sprocket wheel. The power transmission system transmits power to the gearbox.Separating corncobs from the stalksThe corn head was designed by the factory in such a way as to form an attack angle with the farm when installed on the combine. The examined 4-row corn head also boasts three head covers that direct the corn stalks into the feeder unit while the combine 8harvester is moving through the field. Thus as the combine moves along the corn fields, corn stalks flow into the feeder unit. Parts directly involved in separating the corncobs from the stalks are the cutter bars (1) and the sprockets (2). As formerly mentioned, the cutter bars are placed on the U-shaped frame and two sprockets are also placed under the frame. The sprockets rotate against each other by means of their movable gear. The direction in which the sprockets rotate is devised in a way that an opposite rotation against each sprocket draws the stalks down (into the cutting bars). Given the conical shape of the sprockets, upon flowing into the feeder unit, the corn stalks do not immediately contact the sprockets; rather, they only gradually get exposed to the sprockets while moving through the feeder unit. The sprockets are installed in such a way as to draw the corn stalks down into the cutting bars. The space between the cutter bars is adjusted based on the dimensions and size of the harvested corncobs in such a way that the cobs cannot freely move through these spaces; in addition, since the sprockets blades overlap each other, the stalk continues to be drawn and the corncob is thus separated from its stalk. The cob breaks along its own axis at its end so that the corncob ears also loosen from the stalk.Figure 3. System for separating the cobs from the stalkConveying corn cobs to the feeder unitOnce separated from the stalk, the cobs should be conveyed to the threshing drum and the concave. This moving is carried out through three conveyors, two of which are installed on the combine header and one inside the combine harvester. Once the crops have been fully separated, they should be conveyed to the header augerso as to be gathered; they are then sent through the conveyor. The first conveyor (“grain conveyor”) is installed in the feeder unit. Machine parts directly involved in conveying the corncobs to the feeder unit include:Conv9eyorchainMotorrollerchainMovingroller10chainBushings placed on the chainFigure 4. Grain conveyorProposed mechanism for reducing lossAs previously mentioned, reducing the amount of loss can be achieved by decreasing the axial tensile force to the minimum effective degree possible, which means that a variance should be created between the cutter bars altitudes in the feeder unit. To create this variance, filler plates are installed underneath a cutter bar in order to place it higher above the other cutter bar.Figure 7. Filler plates11It should be noted that the chain conveyor mechanism and the chain tightener spring mechanism are also positioned on the cutter bars. Moving the position of the cutter bars repositions these mechanisms as well; therefore, changes that should be made to all three parts are described:Creating variance in the altitude of a cutter barThe intended variance to be createdbetween the cutter bars altitudes for testing the reduced rate of corn loss was 10 and 15mm; the filler plates used for creating this altitude variance had a diameter of 5mm.Figure 8. The feeder unit frameThe corn head has 4 rows, that is, four separating mechanisms; one mechanism received 10mm of altitude variance, another one received 15mm of it, and the other mechanisms remained intact so that the amount of loss in each harvesting path could be examined and the effect of the amount of altitude variance on the degree of grain loss could be measured.Figure 9. Cutter bars12Repositioning the chain tightener spring mechanismThe chain tightener spring is placed on top of the cutter bars; changing the position of the cutter bars thus repositions this spring as well. The chain tightener spring can only be moved vertically; therefore, the mechanism itself will not be modified, instead, the screws mounting the mechanism on the U-shaped frame will only be placed 20mm higher than their previous position.Figure 10. Chain tightener spring mechanismGrain conveyor chain mechanism installation and set upThe conveyor chain mechanism is also placed on top of the cutter bars; therefore, changing the position of the cutter bars repositions this mechanism as well. As previously mentioned, the grain conveyor chain mechanism consists of two roller chains (a motor roller chain and a movable roller chain) and a chain, and each feeder unit contains two grain conveyor mechanisms. The movable roller chain is placed on the L-shaped tightener spring mechanism; moving the latter results in the modification and repositioning of the movable roller chain. The grain conveyors motor roller chain is positioned along the axis of the movable gear of the gearbox conveyor chain. Given that the motor roller chain should also be repositioned along the aforementioned axis once the position of the cutter bars changes, the length of the axis should be adjusted and suitable filler gaskets should be designed for the accurate adjustment of the space.Figure 11. Mounting the chain mechanism on the feeder unit frame13As previously mentioned, modifications are only made totwoout of the four units existing in the feeder unit; in one of the units, one cutter bar is placed 10mm higher above the adjacent cutter bar and, in another unit, one other cutter bar is placed 15mm higher above the adjacent one. Therefore, the length of the axis of the gearbox conveyor chains movable gear should be increased by 20mm.Figure 12. Mounting the gearbox when the axes altitudes varyThis axis, which was welded to the center of the gearbox, is removed; a new axis with more suitable length is designed and welded instead to the gearbox. Modifications are only made to two out of the four units of the header feeder unit.Figure 13. Mounting the sprockets and the gearboxFiller gaskets with a diameter of 5mm were used to mount the roller chains up to the desired altitude. The present study employs a sample altitude variance of 10 and 15mm. In order to place the conveyors motor roller chains in the two chosen units of the feeder unit, two filler gaskets were used in one unit and three in the other one.14Figure 14. Mounting the roller chain when the altitudes varyMounting the movable and the motor roller chains higher up to the desirable altitude made the installation of all parts of the feeder unit in the desirable positions possible.Figure 15. Mounting all feeder unit platesExamining farm operations including system settings and method of information collectionOnce the harvesting unit of the combine harvester is prepared and properly installed by replacing the defective pieces with new ones adjusted to the metallurgical structure in mind, the combine harvester was transferred to the 400 acres farm property of Seed and Plant Improvement Institute in order to be evaluated based on its harvesting performance. It is worth noting that the initial investigations revealed that the sensitive pieces of the header were made of ordinary iron materials and their excessive corrosion was owing tothe use of poor material; however, the material used in making the pieces was modified and the new pieces were installed on the harvesting unit.In the trial run of the new pieces installed on the combine, 2 differentareason the farm were harvested;the below Figures displays the second area harvested and the movement of the combine on the rows.15Figure 16. The harvesting head during the trial run on the farmPrior to harvesting the crops in the 400 acres farm property of Seed and Plant Improvement Institute, hygrometry tests were conducted on the crops. The hygrometry test was carried out in 2 to 3 different areas in each patch of the land so as to measure the correct harvesting moisture content.Below Figures s show the corn kernels being removed and their moisture content being examined.Figure 17. Hygrometry test on the farmIn addition, the rotation of the threshing drum was tested prior to harvesting the crops so as to ensure its reliability. The threshing drums rotation as shown on the telemeter was read several times and its approximate rotation was set at 780rpm so as to prepare for the harvesting operation.Figure 18. Reading the threshing drums rotation and optimizing it for harvestThe entire crop in the two areaspresented by theSeed and Plant Improvement Institute were harvested; sampling and combining the remainder of the harvested crop was performed and measured with standard methods.16Figure 19. Post harvest farmThe prerequisites for performing this research in the 400 acres farm property of the Seed and Plant Improvement Institute, Maize and Forage Crops Research Department, were: Threshing drum speed of 750rpm and crop moisture content of 11.6% on dry basisTable 1. Comparison of mean, standard deviation, and standard error of the meanPaired Samples StatisticsMean Std. DeviationStd. Error MeanGL3 GL412.95809.428011.763188.677163.037242.24043As shown in Table 1, the mean combine loss at the header is higher in GL3treatment compared to GL4; in other words, the amount of loss in GL4 treatment is lower than GL3. That is to say, there is a lower amount of loss at the header when the space between the cutter bars is 15mm rather than 10mm.Table 2. Comparison of means and mean differences of the two treatments using a 2-tailed paired t testPaired Samples TestPaired DifferencesTreatmentsMean Std. DeviationStd. Error Mean95% Confidence Interval of the Differencet df Sig. (2-tailed)17Lower UpperGL3 - GL4 3.5300 4.17792 1.07873 1.2163 5.8437 3.27 * 14 .006Table 2 shows that, for the paired data, the mean difference is 3.53 g/m2 , the standard deviation 4.18 and the standard error of the mean 1.08 g/m2. The minimum and maximum confidence intervals are 1.22 g/m2 and 5.84 g/m2 respectively. The 2-tailed paired t test showed that, at a probability level of 1%, the measured is 3.27 g/m2 with an alpha lower than 5%. In other words, there is a significant difference between the treatments.Figure1. Mean grain loss with the combine corn headAs shown in Diagram 1, treatment with the 15mm filler has a lower amount of grain loss compared to the treatment with the 10mm filler and the one without any.In Iran, corn harvesting is accompanied with a great amount of grain loss. Harvesting machines can significantly contribute to the reduction of grain loss in the process of harvesting; however, improper machine design and the use of poor material in their construction has led to a great degree of difficulty in harvesting, which is why examining these machines is of great importance.CONCLUSIONSResults obtained from the harvests and their amounts of grain loss indicate that, in conventional headers wherein a vertical force is exerted to separate the stalks, damage to the crops is too great and the amount of less excessive. Given results of the present study and their significance as manifested on the cutter bars, it is necessary to make modifications to combine headers made in Iran so as to reduce the amount of grain loss in them. Attention should be paid to the materials used for the construction of headers, particularly the cutter bars, the straw walkers, the pulling chains and the axes so as to reduce the amount of loss at the combine header. Measuring grain moisture content, 18ensuring the proper rotation of the threshing drum and the concave and adjusting the space between them prior to starting the harvesting process greatly contribute to reducing the amount of grain loss we currently experience with combine corn heads.19联合收割，脱粒和分拣系统的优化用以降低玉米损失Roohollah Mohammad Sanabadi Aziz，Sherwin Amini摘要：用联合收割机收割玉米会导致一定程度的损失，从而降低利润;虽然这种损失不能完全消除，但可以控制在合理的程度。准备用于收获玉米的联合收割机是一个包括更换收割头和凹入以及盖板放置在脱粒滚筒上的过程。收获玉米的一个主要障碍是防止谷物损失，谷物损失主要发生在联合收割机头（将玉米穗轴与秸秆分离时）以及脱粒滚筒和凹面（因为玉米芯断裂）的收获过程中。目前的研究是在种子和植物改良研究所，玉米和饲料作物研究部门的一个 400 英亩的农场中进行的，其前提条件是脱粒滚筒转速为 750rpm，作物含水量为干基的 11.6。作物产量和测量的谷物损失量表明，当使用传统的施加垂直力来分离茎的头部时，收获期间谷物损失的程度变得过大;这些头部造成大量的作物损失。本研究的结果表现在联合刀杆上;因此，为了减少联合收割机收割损失，伊朗制造的联合收割机应该进行重大修改。在这方面采取的第一步是设计和实施对机器的两个主要部分即“玉米头”和“进料器单元”的必要修改。关键词：玉米联合收割机 减少 收割机联合 改造脱粒鼓和凹槽喂料机组1.简介世界上越来越多的人口面临粮食短缺的问题，因此需要扩大玉米等高产作物的生产，以克服这一问题。2.材料和方法该项目旨在优化联合收割机头系统，并实现玉米生产中的最小谷物损失;因此，第一步是购买玉米联合收割机以研究和分析其系统。然后确定在头部发生的玉米损失的来源以及系统中发生的其他类型的损失，以便在考虑所有因素的情况下确定它们的贡献机制，然后准备对现有头标进行标准测试和评估。下一阶段是检查联合收割机的运行机制，并根据联合收割机出现损失的原因对其进行修改以实现最小化目的。最后一步是对农场修改后的联合收割机头进行试运行，以便检查修改后的粮食损失程度，并将其与以前的状态进行比较。检查组合标题20被检查的系统是可以安装在约翰迪尔 955 联合收割机上的 4 排玉米头。这个头被设计用来将玉米棒从茎秆中分离出来，然后将它们喂给装置。这个头有4 行，彼此间固定的距离为 75 厘米。该系统的主要部分是：a）框架b）电力传输系统c）收割机（玉米切割机）d）谷物输送机玉米头技术规格：所需功率：45 马力输入旋转：600 rpm 行数： 4收获率：每 8 小时 4 英亩重量：1000 公斤长度：320 厘米宽度：280 厘米身高：130 厘米图 1.玉米头的概况设计并提出一个合适的机制在项目的这个阶段，首先检查直接与作物接触并造成玉米损失的头部机制; 然后根据设想的机制，考虑到被检查的头部部件的功能进行了必要的修改。检查组合头的进料器单元机构当联合收割机沿着农场运行时，农作物在喂给单元，然后将玉米棒从秸秆中分离出来。进料单元负责分离过程; 该装置的可移动部件从机械嵌入式齿轮箱获得动力。能够分离和喂入玉米芯的部分如下：21图 2.馈线单元机构U 形框架刀杆链式输送机构链条张紧器弹簧机构链轮稻草步行者变速箱饲养机构（现有联合收割机头）馈线单元部分可分为固定部分和可移动部分两大类。 固定部分包括 U 形框架，链条紧固器弹簧，刀杆和吸管助行器。活动部件包括链条，滚子链条和链轮。 动力传动系统向变速箱传递动力。从茎中分离玉米芯玉米头是由工厂设计的，当安装在联合收割机上时与农场形成一个攻角。被检查的四行玉米头还拥有三个顶盖，当联合收割机在田间移动时，玉米秸秆直接进入进料器单元。因此，当联合收割机沿着玉米田移动时，玉米秸秆流入馈线单元。直接涉及将玉米棒从茎上分离出来的部件是切割条（1）和链轮（2 ）。如前所述，刀杆放置在 U 形框架上，两个链轮也放置在框架下。链轮通过其可动齿轮相互转动。链轮旋转的方向被设计为使得相对于每个链轮的相反旋转将茎向下（进入切割条）。鉴于链轮的圆锥形状，在流入进料器单元时，玉米秸秆不会立即接触链轮;相反，它们在通过进料器单元时仅逐渐暴露于链轮。链轮的安装方式可以将玉米秸秆拉入切割棒中。根据收获的玉米芯的尺寸和大小调整切割器棒之间的空间，使得玉米棒不能自由地穿过这些空间;此外，由于链轮的叶片彼此重叠，所以茎杆继续被拉伸，并且玉米芯因此与茎分离。玉米棒的末端沿其自身轴线断开，以使玉米芯耳朵也从茎上松开。22图 3.从茎中分离玉米棒的系统将玉米棒输送到进料器一旦从茎中分离出来，应将玉米棒输送到脱粒滚筒和凹部。 这种移动是通过三台输送机完成的，其中两台安装在联合收割机上，另一台安装在联合收割机内。 一旦农作物完全分开，它们应该被运送到联合收割机并收集起来; 然后它们通过传送带被送出。 第一台输送机（“谷物输送机”）安装在进料装置中。直接涉及将玉米芯输送到进料单元的机器部件包括：输送链条电机滚子链条移动滚子链条套在链条上图 4.谷物输送机建议减少损失的机制23如前所述，可以通过将轴向拉力减小到可能的最小有效程度来实现减少损失量，这意味着在进料器单元中的切刀棒的高度之间应该产生变化。 为了产生这种差异，填料板安装在切刀杆下方，以便将其放置在其他切刀杆的上方。图 7.填充板应该注意的是，链式输送机构和链条张紧器弹簧机构也位于刀杆上。 移动刀杆的位置也重新定位了这些机制; 因此，应该对所有三个部分进行更改：创建切割条高度的差异为了测试减少的玉米损失率，在切割杆高度之间创建的预期差异是 10 和15mm; 用于产生这种高度变化的填充板具有 5mm 的直径。图 8.馈线单元框架玉米头有 4 排，即四个分离机构; 一个机制接受 10 毫米的高度变化，另一个机制接受 15 毫米的高度变化，其他机制保持完好，以便可以检查每个收获路径的损失量，并且高度变化量对谷物损失程度的影响可以 被测量。24图 9.切刀条重新定位链条张紧器弹簧机构链条张紧器弹簧放置在切刀条的顶部; 因此改变刀杆的位置也重新定位了这个弹簧。 链条张紧器弹簧只能垂直移动; 因此，该机构本身不会被修改，相反，将该机构安装在 U 形框架上的螺钉只会比其之前的位置高出 20mm。图 10.链条张紧器弹簧机构粮食输送链机制的安装和设置输送链机构也放置在刀杆的顶部; 因此，改变刀杆的位置也会重新定位该机构。 如前所述，谷物输送链机构由两个滚子链（电机滚子链和可移动滚子链）和一个链条组成，每个馈送单元包含两个谷物输送机构。 活动滚子链置于 L 形紧固件弹簧机构上， 移动后者导致可移动滚子链的修改和重新定位。 谷物输送机的电机滚子链条沿齿轮箱输送机链条的活动齿轮轴线定位。 考虑到一旦切刀条的位置发生变化，电机滚子链也应该沿着上述轴重新定位，轴的长度应该被调整，并且适当的填充垫应该被设计用于精确调整空间25图 11.将链条机构安装在供纸单元框架上如前所述，仅在馈线单元中存在的四个单元中进行修改; 在其中一个单元中，一个刀杆位于相邻刀杆上方 10mm 处，另一个单元中另一个刀杆位于相邻刀杆上方 15mm 处。 因此，变速箱输送链的可动齿轮的轴线长度应增加20mm。图 12.当轴的高度变化时安装齿轮箱该轴被焊接到齿轮箱的中心，被移除; 设计一个更合适长度的新轴并将其焊接到齿轮箱上。 仅对标题进纸单元的四个单元中的两个进行修改。图 13.安装链轮和齿轮箱26使用直径为 5mm 的填料垫片将滚子链安装到所需的高度。 本研究采用 10和 15mm 的样本高度变化。 为了将输送机的电机滚子链放置在供料单元的两个选定单元中，一个单元使用两个填充垫圈，另一个单元使用两个填充垫圈。图 14.海拔高度变化时安装滚子链将可动链轮和电动滚筒链条安装到理想的高度，可以将喂纱装置的所有部件安装在理想的位置。图 15.安装所有进料器单元板检
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