土豆挖掘機的設計-馬鈴薯收獲機【三維SW】,三維SW,土豆,挖掘機,設計,馬鈴薯,收獲,三維,SW 本科畢業(yè)設計(論文) 題目：土豆挖掘機的設計 院 系： 機械工程學院 專 業(yè)： 機械設計制造及其自動化 學 號： 姓 名： 指導教師： 2016年4月 摘要 土豆作為人們的主要食品之一，具有豐富的營養(yǎng)價值，人們在日常生活中，人們都會圍繞土豆來做出各種不同的菜肴，例如炒菜，燉湯等等。而通過刀具切削土豆片會很麻煩，如果有能夠對土豆進行自動挖掘的機械，那樣在一定程度上會大大提高挖掘效率和質量。 該土豆挖掘機主要由機架、連接桿、擺臂、連接件、曲柄、抖動輪、挖掘鏟、定位軸、地輪等等零部件組成。動力是通過拖拉機帶動該土豆挖掘機在農(nóng)田里面進行自動挖掘作業(yè)。該機效率高，產(chǎn)能好，適合批量挖掘土豆的場所。 關鍵詞：土豆挖掘機；機架；挖掘鏟；產(chǎn)能 I Abstract potatoes as one of the main food of the people, with rich nutritional value, people in daily life, people will around the potato to make a variety of dishes, such as cooking, soup, and so on. And through the cutting tool cutting potato chips will be very troublesome, if there is to be able to peel the skin of the machine, then to a certain extent, will greatly improve the efficiency and quality of the peel. The potato peeler is through artificial potatoes into potato peeling machine barrel inside, at the bottom of the motor through the transmission gear to drive the transmission shaft to rotate, so as to drive the rotating body rotation, rotation body spot welding can be through the potatoes with a rotating body surface friction and skin small metal grinding, potatoes and with the rotary body to rotate together, and the inner wall of the cylinder body welding scraping knife, that comes with the rotation of the rotating body, the inside of the barrel body of potatoes has been constantly and the surface of a rotating body of small metal grinding blade and the inner wall of the barrel body scraping knife friction to the skin effect Key words:Potato peeling machine,cutting tool,rotating body, peeling II 目 錄 摘要 I Abstract II 1緒論 1 1.1 課題的來源與研究的目的和意義 1 1.2 本課題研究的內容 2 1.3 國內外發(fā)展現(xiàn)狀 2 2土豆挖掘機總體結構的設計 4 2.1 土豆挖掘機的總體方案圖 4 2.2 土豆挖掘機的工作原理 4 2.3 機械傳動部分的設計計算 5 2.3.1V帶傳動的設計計算 7 2.3.2軸承的設計計算 8 2.3.3軸的設計 8 3各主要零部件強度的校核 10 3.1機架強度的校核與計算 11 3.2轉軸強度的校核計算 12 3.3軸承強度的校核計算 14 4土豆挖掘機中主要零件的三維建模 15 4.1機架的三維建模 17 4.2挖掘鏟的三維建模 18 4.3擺臂的三維建模 20 4.4土豆挖掘機的三維建模 22 結 論 23 致 謝 24 參考文獻 25 III 1 緒論 1.1 課題的來源與研究的目的和意義 在英國，土豆挖掘設備等產(chǎn)業(yè)越來越多地將工場設在河邊，利用人工來對土豆進行挖掘。在這樣的生產(chǎn)需要下，19世紀初出現(xiàn)了新型的土豆挖掘機，1965年，德國人費倫斯發(fā)明了半自動的土豆挖掘機，降低了人工的浪費。1981年費倫斯又創(chuàng)制出提供回轉動力的土豆挖掘機，擴大了土豆挖掘機的應用范圍。土豆挖掘機的發(fā)明和發(fā)展，使土豆等類似食品的加工行業(yè)和工業(yè)生產(chǎn)都得以機械動力化。土豆挖掘機幾乎是20世紀唯一的加工土豆的機械。 當今社會，無論從挖掘數(shù)量、質量、經(jīng)濟效益等各方面來衡量，此次設計的新型土豆挖掘機，它已經(jīng)遠遠超越了以往的傳統(tǒng)的土豆挖掘機，并成為各國爭相發(fā)展的行業(yè)。1986年江蘇的永趕公司實現(xiàn)了土豆挖掘機的創(chuàng)新設計，并通過打入亞洲以及南美市場，取得了不錯的成績。從20世紀起，新型的土豆挖掘機不斷誕生，進入20世紀，出現(xiàn)各種實驗應力分析方法，人們已能夠通過機電的有機結合設計出智能化的土豆挖掘機，相信在不久的將來，改機電一體化智能產(chǎn)品，將會得到越來越廣闊的應用。土豆作為人們的日常的食品，是人們的生活的需要。為了實現(xiàn)土豆的自動化挖掘，從而來代替?zhèn)鹘y(tǒng)的人工削皮來提供勞工效率，適應現(xiàn)代化機械工業(yè)高速發(fā)展的需要，所以在機械設備中它們的挖掘設備的生產(chǎn)也有著嚴格的要求。傳統(tǒng)的土豆在沒有自動挖掘設備而需要人工挖掘的情況下，挖掘效率低下，勞動強度大，所以設計一個專用的土豆挖掘勢在必行。 通過對實際的生產(chǎn)設備進行考察，從而提出了新型土豆挖掘機的結構組成、工作原理，擬定了土豆挖掘機總的指導思想，得出了該新式土豆挖掘機的優(yōu)點是高效，經(jīng)濟且易維修的結論。 根據(jù)結合自身所學和本次所選課題的難易度，覺得無論是在知識層面還是在軟件的運用技能上面，該課題很適合我，加之本課題來源于當今社會機械工業(yè)土豆挖掘設備的創(chuàng)新和更新?lián)Q代基礎之上，通過設計出土豆挖掘機，從而來滿足當今社會土豆挖掘設備不足的缺陷。 1.2 本課題研究的內容 土豆作為人們的日常食物的一種，經(jīng)常出現(xiàn)在人們的餐桌上面。本次設計的土豆挖掘機主要是針對日常生活中見到的土豆來進行的，由于該土豆挖掘機的挖掘鏟采用焊接的形式，其形狀采用鏟形，所以它的強度和結構設計合理，并且能夠滿足對指定區(qū)域的土豆挖掘干凈的條件。 本次設計主要針對土豆挖掘機進行設計，從土豆挖掘機的整體方案出發(fā)，然后具體細化出具體內部結構，其具體內部結構主要包括以下幾個方面： 1、到圖書館里查閱大量相關知識的資料，搜集出各類土豆挖掘機的原理及結構，挑選相關內容記錄并學習。 2、分析土豆挖掘機的結構與參數(shù) 3、確定設計總體方案 4、確定具體設計方案（包括挖掘機構的設計，V帶傳動的設計，電機，軸承等的選型設計等等） 5、土豆挖掘機的三維圖的繪制、CAD裝配圖、零件圖的繪制。 6、說明書的整理 1.3 國內外發(fā)展現(xiàn)狀 我們在2002來自于王健的以前的資料，他數(shù)十年的廢寢忘食建造了一個簡單的土豆挖掘機機構，開純機械時代。王健更設計出多功能復合土豆挖掘機，在這之后，臺灣教授顏洪森以傳動的土豆挖掘機為基礎，開發(fā)了一系列的土豆挖掘機，如四連桿式，六連桿式等等土豆挖掘機，查建中和其他人一起以凸輪機構為對象，共同鉆研考慮怎樣改良按壓力引發(fā)的角度以及零部件的分理。總之，傳統(tǒng)的對象加上科學的分析和先進的理論，使得土豆挖掘機在國內的研究范圍和深度得到了極大的豐富和發(fā)展。 何人最先取得此項專利已無可知曉，只了解到外國科學家在十九世紀末建造出了一部類似于土豆挖掘機的機械，整體部分是用齒輪以及連接桿件機構組裝，但是卻沒有做出實物來加以佐證.20世紀初又有人運用齒輪以及連接桿件體系制造出類似的土豆挖掘機，然而相關資料中并沒有找到對這個作品的介紹，所以那個時候有關土豆挖掘機的研究還僅能思組成以及運動起來的規(guī)律。同期，又有兩位發(fā)明家麥吉以及弗蘭科創(chuàng)作了首部徹底用計算機操縱的土豆挖掘機。接下來幾年有關此機器的設計被充分的融入了運行操縱理論。1979年席羅思在行進土豆挖掘機里加入了操縱水平行走的儀器，同樣在腿上加入了保持和校對偏向的裝置。20世紀末布朗、羅布特以及莎普恩斯研究了加入了液壓部件和直流電機的相應土豆挖掘機。這都意味著人類對機械體系的認識已從簡單的考慮邁入了整體操縱、計算機和高新科技的相互融匯貫通的康莊大道。 從廣闊的視野、各種各樣的活動，還有和學術報告、規(guī)范標準以及另外別的角度的的詳細內容，我們得到了包含定位、性質以及應用土豆挖掘機的大環(huán)境。土豆挖掘機已發(fā)展到注重提高生產(chǎn)效率，成品質量穩(wěn)定性。最近，超多的市場已經(jīng)建立了土豆挖掘機的商業(yè)用途，像土豆挖掘機，它的應用已經(jīng)滲透到家庭家居生活等。出色的土豆挖掘機技術不僅實現(xiàn)創(chuàng)建一個新的市場，也為提高人們的生活水品做出了非常重要的貢獻。在一個國家或地區(qū)有土豆挖掘機具有普遍偏向的方式。今后，會更加流行正在蓬勃發(fā)展的土豆挖掘機。OMG國標早就認可中介范例，ISO資質也授與了能減少勞動力的土豆挖掘機。即使在大規(guī)模對土豆進行挖掘的活動，這是越來越多的土豆挖掘機的使用。根據(jù)土豆挖掘機技術應用在通訊，家電，汽車，醫(yī)療設備和其他，土豆挖掘機已被廣泛認可。它是一種動力，看來像它會導致一個新的行業(yè)。土豆挖掘機研發(fā)情況固然都在被上述所整理，然而這些仍然是顯示出要把土豆挖掘機推向消費者。歐美等發(fā)達國家成立有相應計劃，本國也需求更好的戰(zhàn)略，方能維持積極地有力發(fā)展。新服務土豆挖掘機對于市場具有應用性很強的領域，比如孜孜不倦的創(chuàng)新產(chǎn)品、醫(yī)療項目、相關福利以及防不勝防的自然性或人為性災難。在另一方面，雖然產(chǎn)自日本的工業(yè)土豆挖掘機依然是行業(yè)里最好的，但其他國家都在奮起直追。在關于實際使用中，美國提出了很多觀點。在美國有建立國家計劃項目，歐洲也是，如Horizon2020，我們的國家也需要更好的政策，才能保持健康的發(fā)展前景。傳統(tǒng)的土豆挖掘機產(chǎn)品圖片如下圖1,2所示： 圖1 圖2 2 土豆挖掘機總體結構的設計 2.1 土豆挖掘機的總體方案圖 土豆挖掘機屬于食品加工設備的一種，通常市面上用到的都是焊接框架式的，因為焊接框架式的土豆挖掘機結構強度足夠，其形狀很容易輕松地就將土豆從地里挖掘出來。該土豆挖掘機主要由機架、連接桿、擺臂、連接件、曲柄、抖動輪、挖掘鏟、定位軸、地輪等等零部件組成。動力是通過拖拉機帶動該土豆挖掘機在農(nóng)田里面進行自動挖掘作業(yè)。該機效率高，產(chǎn)能好，適合批量挖掘土豆的場所。 其總體方案圖如下圖1-1所示： 1-1 土豆挖掘機總體方案圖 2.2 土豆挖掘機的工作原理 該土豆挖掘機主要由機架、連接桿、擺臂、連接件、曲柄、抖動輪、挖掘鏟、定位軸、地輪等等零部件組成。動力是通過拖拉機帶動該土豆挖掘機在農(nóng)田里面進行自動挖掘作業(yè)。該機效率高，產(chǎn)能好，適合批量挖掘土豆的場所。 2.3 機械傳動部分的設計計算 2.3.1 V帶傳動的設計計算 （1）設計功率 ＝1.2 P－傳遞的功率 （2）選定帶型 根據(jù)和選取普通V帶C型，－小帶輪轉速，為1350r/min （3）傳動比 1.76 ＝＝ （4）小帶輪基準直徑（mm） 由B1表8－1－12和表8－1－14選定 ＝100mm>＝75r/min （5）大帶輪基準直徑（mm） 由B3表8－7得=150mm （6）帶速驗算 （7）初定軸間距（mm） （8）所需帶的基準長度（mm） ＝ ＝650mm 帶型選擇為A－900 （9）實際軸間距 （10）小帶輪包角 = = （11）單根V帶的基本額定功率 根據(jù)系統(tǒng)工況，我們可以取=0.37kw （12）時單根V帶型額定功率增量 根據(jù)系統(tǒng)工礦，在這里我們取=0.15kw （13）V帶的根數(shù)Z Z = －小帶輪包角修正系數(shù)取0.96 －帶長修正系數(shù)查取0.87 （14） 單根V帶的預緊力 = =134（N） m－V帶每米長的質量（kg/m）查B1表8－1－24，取0.1k/gm （15）作用在軸上的力 －考慮新帶初預緊力為正常預緊力的1.5倍 （16）帶輪的結構和尺寸 帶輪是傳動系統(tǒng)的傳動組件之一，需要有足夠的剛度和強度才能滿足要求。根據(jù)系統(tǒng)的需求，我們可以選擇鑄鐵作為帶輪的材料，因為鑄鐵的強度和剛度方面度能夠滿足系統(tǒng)的需求。 帶輪的材料為HT200，查B1表8－1－10得基準寬度制V帶輪輪槽尺寸，根據(jù)帶輪的基準直徑查B1。 2.3.2軸承的設計計算 已知軸承預計壽命20×365×8=58400小時； (1）已知nⅡ=458.2r/min?兩軸承徑向反力：FR1=FR2=500.2N； 初先兩軸承為深溝球軸承6208型。 根據(jù)課本P265（11-12）得軸承內部軸向力FS=0.63FR則FS1=FS2=0.63FR1=315.1N； (2)∵FS1+Fa=FS2Fa=0? 故任意取一端為壓緊端，現(xiàn)取1端為壓緊端 FA1=FS1=315.1N???FA2=FS2=315.1N； (3)計算當量載荷 P1、P2根據(jù)課本P263表（11-9）取f?P=1.5;根據(jù)課本P262（11-6）式得 P1=fp(x1FR1+y1FA1)=1.5×(1×500.2+0)=750.3N；? P2=fp(x2FR1+y2FA2)=1.5×(1×500.2+0)=750.3N；? (4)軸承壽命計算 ∵P1=P2故取P=750.3N；? ∵深溝球軸承 ε=3； 2.3.3軸的設計 軸作為機器的一個關鍵組成部分，其為各類傳動部件的安裝，傳動的扭矩和旋轉運動圍繞軸進行，而且經(jīng)過軸承和機架連接。為了滿足定位軸上的緊固件和容易加工和裝配的軸類零件和拆卸，通常軸設計成階梯軸。軸系的零件是由軸和它上邊的零部件構成一個裝配體系，研究軸的過程中不僅要研究軸體自己的數(shù)據(jù)，還要將系統(tǒng)里的全部零部件融合在一起。 因為用于振動的傳遞的軸體不僅要傳送扭矩，還得經(jīng)受住彎矩，是以本人研究的階梯性軸是轉動軸。因為確定了小帶輪的參數(shù)，相應的大帶輪隨之確定。接下來的工作就是計算軸體的直徑了。軸體的研究需要憑借扭轉強度來調整彎曲的強度，因為可用作軸的原料比較多，所以必須得明確軸的應用環(huán)境，還有規(guī)定諸如剛度，強度以及別的機構機能?？梢允褂脽崽幚磉@種方法，當然也要琢磨怎樣使加工簡單并且花費較少，用研究計算所得的數(shù)據(jù)以確定軸體的用料，故采取45號鋼當成軸體的原料，它需要40MPa的切應力。然后需要做正火或者調質處理來確保它的力學性能。 由前知：卷筒上傳遞的功率是12.9kw，轉速n=3.9m/min，選用鋼，為保證其機械性能，應進行調試處理。 軸徑的初步估算 估算公式： d≥A0 式中A0是與材料有關的系數(shù)，查[1]P表15-3 得A0=108 d≥A0=108×=15.76 圓整，取d=16mm 由于此軸是固定心軸，受力情況并不嚴重。因此，接上式估算的軸徑可作為軸的最大直徑。參考現(xiàn)有同類產(chǎn)品，取最小軸徑d=15mm。 （1）確定軸上零件的布置方式。為使結構緊湊，并考慮具體的工藝性和強度要求，將大齒輪與卷筒一側對稱地安裝在軸頸處。即大齒輪在卷筒右側，通過鍵與卷筒固聯(lián)在一起。軸承兩端裝有軸承蓋，內有檔油板和密封圈。軸承蓋用螺釘M1220與卷筒固定在一起。 （2）根據(jù)工藝和強度要求把軸制成階梯形，這樣可以使軸上零件定位可靠并且拆裝方便。 3 各主要零部件強度的校核 3.1機架強度的校核與計算 機架的選擇根據(jù)整個系統(tǒng)的總重量來定，方管機架受力分析得出，由分析得出底架在平衡狀態(tài)下只受地面對其的支撐力和在其表面上物體所給的壓力。見下圖： 即物料和底架上面的所有零部件等等給的壓力為G=20000N（10000Kg）+(1000X20N)=30000N; 根據(jù)方管承載力計算公式： M=Pac/L （僅用于截面) f=M/W≤材料的許用應力（彈性抗拉強度/安全系數(shù)）。 M=Pac/L=11960xL，本次設計初定L為1200mm 則M=13456N.M ，初定方管為40x40x5。計算W得出 折算后位270Mpa 查的普通碳素結構鋼Q235A的抗拉強度為375~500Mpa，由于270Mpa遠遠小于375Mpa，所以初定方管滿足要求。 3.2轉軸強度的校核計算 受力分析：卷筒部件的大齒輪和卷筒未與軸直接接觸，但其上的力通過軸承傳遞到了主軸上。因此，主軸所受軸承的力與卷筒所受軸承的力大小相等方向相反。另外，主軸兩端還受兩個支承架的支承力。若考慮重力的作用，主軸還受卷筒部件的重壓作用。 軸的空間受力圖： O X y z 圖3-2 軸的空間受力圖 由前知：R =392N，R=24500N；R=31642N，R35874N，估計卷筒重量約為154公斤，則G=1509N。將軸上作用力分解為水平面受力圖和垂直面受力圖，求出水平面上和垂直面上的支承點反作用力，并畫出彎矩圖： 支反力： 根據(jù)平衡方程R+R=R+G+R R．64+G．236+R．408=R．472 解得，R=5383.8N，R=28159.2N 彎矩圖： 圖3-3 彎矩圖 YX面受力圖： 支反力： 根據(jù)平衡方程 R′+R′=R′+R′ R′．64+R′．408=R′．472 解得，R′=26042.2N， R′=34331.8N 彎矩圖： 圖3-4 彎矩圖 合成彎矩圖M= 圖3-5 合成彎矩圖 對照結構圖，分析合成彎矩圖，可知主軸較危險的三個部面分別是：中間軸頸110的右端面Ⅰ，右端面軸承的中間部面Ⅱ，右端軸頸的左端面Ⅲ。（主軸結構圖）。 這三個合成彎矩分別是： M= = =2669644 M=2841782.4 M= = =1243279.8 因為Ⅰ、Ⅱ處的截面直徑相同，M＞ M，只需驗算M就行了。 直徑校核： 心軸的截面尺寸是根據(jù)彎曲強度來計算。其危險截面的尺寸可按下式確定。 d= 式中，M——最大彎矩 []——許用彎曲應力 ——對于實心軸=0，對于空心軸=，d：軸內徑，d：軸外徑，對于卷筒主軸，查[Ⅰ]P，45鋼，=355MP。取安全系數(shù)n=2.0，則[]===177.5 MP。主軸是實心軸，=0。 ∴d≥。 則d===53.18mm＜75mm d===54.29mm＜85mm 由以上計算可以看出，主軸強度足夠。 3.3軸承強度的校核計算 3.3.1滾動軸承的選擇 滾動軸承為雙列圓錐滾子軸承350324B，由文獻[2]表得KN，KN，，。 3.3.2壽命驗算 軸承所受支反力合力 N （4.1） 對于雙列圓錐滾子軸承，派生軸向力互相抵消。 ，N 由文獻[2]表得， ， N （4.2） 按軸承B的受力大小驗算 h （4.3） h=年 由于拖拉機減速箱的運轉平穩(wěn)，必須選擇較大壽命的軸承，軸承能達到所計算的壽命。 經(jīng)審核后，此軸承合格。 4 土豆挖掘機中主要零件的三維建模 4.1機架的三維建模 4-1 機架 4.2挖掘鏟的三維建模 4-2 挖掘鏟 4.3擺臂的三維建模 4-3 主動齒輪 4.4土豆挖掘機的三維建模 4-4 土豆挖掘機 結 論 到如今，畢業(yè)設計總算接近尾聲了，通過這次對于土豆挖掘機的設計，使我們充分把握的設計方法和步驟，不僅復習所學的知識，而且還獲得新的經(jīng)驗與啟示，讓我收益頗多。特別是針對機械的機構設計這部分，我感觸最深。對于次次設計的土豆挖掘機，主要的傳動的機構是齒輪傳動，針對這個機構的設計，我花費了較多時間和精力，通過查找相關的齒輪傳動的設計資料以及土豆挖掘機的相關問題來確定齒輪的模數(shù)和齒數(shù)，以及齒輪的內孔的設計，直到最后齒輪的強度校核部分。經(jīng)過這個過程的學習和設計，讓我印象尤為深刻。 在以后的工作中，我相信我還會遇到很多類似的問題，但是有了這次的學習和設計經(jīng)歷，我想我已經(jīng)初步具備了設計一個機械設備的能力，我已經(jīng)做好了準備，在以后的工作中，邊工作邊學習，爭取在工作中提高，在工作中學習，爭取做一個對于社會，對家庭有用的人。 通過本次設計,讓我學習到了許多知識，特別是對傳動機構的應用方面，是我收獲最大的地方。本次的設計的傳動機構包含了齒輪傳動機構這一最典型的機構，通過查找與它相關的設計資料，到計算帶動筒體轉動所需要在輸出扭矩從而對齒輪機構進行設計，包括傳動帶輪的選型，例如帶型，帶寬的確定以及之后的軸承強度校核部分的設計，都花費了我好多精力。同時，也讓我學到了好多知識。 在相關的實際問題的討論中，我的導師總是孜孜不倦的引導著我，幫助著我。每周一次的進度檢查和問題討論，促使我在正確的道路上大步前進，不僅工作的按時保質保量的完成得到了保證，我本人的研究能力，工作的態(tài)度也得到了充分的鍛煉和提高。這些寶貴的品質影響著我，毫無疑問，它們對我以后的工作，學習，生活都會起到深遠而長久的良好影響。也能為人生打下一個夯實地基礎！ 在具體的研究設計過程中，同學們也在平日的學習與生活中提供了無私與周到的幫助，充分用他們的工作熱情感染著我，鼓勵著我，讓我少走了很多彎路，再次一并致謝！另外也感謝我的父母，朋友和同學們的幫助。在做設計感覺受挫，枯燥與迷茫時，是他們在悉心的為我釋放壓力，鼓勵我不要氣餒，勇敢面對。每周一次和父母的通話，與朋友和同學的長談后都使我精神放松，斗志倍增，以飽滿的熱情重新投入到工作中去，感謝他們，正是他們的不懈支持和充分理解才能使我順利完成畢業(yè)設計。 最后，感謝學校各位領導與老師給了我在濱海學院學習生活四年以及參加這次畢業(yè)設計的寶貴的鍛煉機會，它使我深刻認識到在知識的汪洋大海面前我是多么無知和微不足道。這是一個最好的時代，也是尊重知識，充分學習知識，掌握知識的時代。只有持續(xù)的不間斷地學習，才不會在激烈的競爭中落后于別人，也才能用自己的真才實學為社會做出自己應有的貢獻。知識是無止境的，無價的，我愿在求真的道路上下而求索！ 致 謝 時間過得很快，論文總算完成了，我的心里感到特別高興和激動，在這里，我打心里向我的導師和同學們表示衷心的感謝！因為有了老師的諄諄教導，才讓我學到了很多知識和做人的道理，由衷地感謝我親愛的老師，您不僅在學術上對我精心指導，在生活上面也給予我無微不至的關懷支持和理解，在我的生命中給予的靈感，所以我才能順利地完成大學階段的學業(yè)，也學到了很多有用的知識，同時我的生活中的也有了一個明確的目標。知道想要什么，不再是過去的那個愛玩的我了。導師嚴謹?shù)闹螌W態(tài)度，創(chuàng)新的學術風格，認真負責，無私奉獻，寬容豁達的教學態(tài)度都是我們應該學習和提倡的。通過近半年的設計計算，查找各類土豆挖掘機的相關資料，論文終于完成了，我感到非常興奮和高興。雖然它是不完美的，是不是最好的，但在我心中，它是我最珍惜的，因為我是怎么想的，這是我付出的汗水獲得的成果，是我在大學四年的知識和反映。四年的學習和生活，不僅豐富了我的知識，而且鍛煉了我的個人能力，更重要的是來自老師和同學的潛移默化讓我學到很多有用的知識，在這里，謝謝老師以及所有關心我和幫助我的人，謝謝大家。 參考文獻 [1]張福學編著.土豆挖掘機的應用.北京：電子工業(yè)出版社，2000：59-62 [2]何發(fā)昌著，邵遠編著.土豆挖掘機的原理.北京：高等教育出版社，1996：77-80 [3]張利平著. 實用技術速查手冊. 北京：化學工業(yè)出版社，2006.12：15-18 [4]李寶仁著. 氣動技術—低成本綜合自動化. 北京：機械工業(yè)出版社，1999.9：80-82 [5]宋學義著. 土豆挖掘機速查手冊. 北京：機械工業(yè)出版社，1995.3：99-101 [6]陳奎生著. 氣與氣壓傳動. 武漢：武漢理工大學出版社，2008.5：208-212 [7]SMC（中國）有限公司. 土豆挖掘機實用技術. 北京：機械工業(yè)出版社，2003.10:230-232 [8]徐文燦著. 土豆挖掘機系統(tǒng)設計. 北京：機械工業(yè)出版社，1995：320-323 [9]高微,楊中平,趙榮飛等.土豆挖掘機結構優(yōu)化設計. 機械設計與制造2006.1：187-189 [10]馬光,申桂英.工業(yè)土豆挖掘機的現(xiàn)狀及發(fā)展趨勢. 中國期刊全文數(shù)據(jù)庫2002年:28-30 [11]李如松.土豆挖掘機的應用現(xiàn)狀與展望. 中國期刊全文數(shù)據(jù)庫1994年第4期:55-58 [12]李明.土豆挖掘機設計.制造技術與機床2005年第7期:77-79 [13]李杜莉，武洪恩，劉志海.土豆挖掘機的運動學分析. 煤礦機械2007年2月:52-55 [14]Technological study of liquid die forging for the aluminum alloy connecting rod of an air compressor[J].journal of materials processing technology，2003:462-464 [15] Hirohiko Arai, Kazuo Tanie, and Susumu Tachi. Dynamic Control of a Manipulator with Passive Joints in Operational Space:388-390 23 Effectiveness assessment of agricultural machinery based on fuzzy sets theoryRajko Miodragovic a, Milo Tanasijevic b, Zoran Mileusnic a, Predrag Jovanc ic baUniversity of Belgrade, Faculty of Agriculture, SerbiabUniversity of Belgrade, Faculty of Mining and Geology, Serbiaa r t i c l ei n f oKeywords:Agricultural machineryEffectivenessFuzzy setMaxmin compositiona b s t r a c tThe quality of service of agricultural machinery represents one of the basic factors for successful agricul-tural production. In this sense, there is a clear need for defining the exact indicator of the quality of thesemachines, according to which it could be possible to determine which machine is optimal for differentworking conditions. The concept of effectiveness represents one of synthesis indicators of the qualityof service of the technical systems. In this paper the effectiveness is defined using the fuzzy set theory,and reliability, maintainability and functionality are used as influence indicators of the effectiveness.In that sense the model for assessing the effectiveness of tractor as a typical representative of agromachinery has been formed. The model is based on integration of linguistic description of the above men-tioned influence indicators using fuzzy set theory and maxmin composition. The model was tested onthe example of three tractors of the same category, which are exploited in climatic and soil conditionsin the wider Belgrade (Serbia) area. Even if the conditions in this experiment were approximately equal,the difference of the achieved effects was attained and very significant, compared to other operationparameters.? 2012 Elsevier Ltd. All rights reserved.1. IntroductionRapid expansion of global demands for agricultural products hascaused much greater development of agricultural technique, apro-pos machines and equipments. It is widely recognized that contem-porary agricultural systems demand careful and detailed planningand control of all relevant biological, technical, technological andother processes. An accurate and reliable predicting of the final out-come for each specified operation, as well as for the complete cropproductionprocess,isofspecialimportance.Demandshaveintensi-fied the introduction of sophisticated experimental, mathematical,statistical, mechanical and other methods in agricultural sciencesduring the last few decades. Besides the demands described above,anadequatetechnicalsystemhastosatisfythecriteriaofproductiv-ity, imposed by the conditions of desired crop production. In mostcases, the capacity of tractor-machinery systems on farms in Serbiais much over the optimal level (Nikolic , 2005), increasing the costsof crop production.Nowadays, the existing mathematical optimiza-tion methods, supported by the high-performance computers, canefficiently resolve the optimization problems (Dette & Weber,1990; Duffy et al., 1994; Mileusnic , 2007; etc.). The formation ofan optimal technical system in order to produce cheaper food,highly impacted reliability of tractors, its maintainability, and thefunctionality of the system.With the beginning of systems sciences development, practicallyafter the II World War, in appropriate engineering and scientific liter-ature a series of concepts have been defined, with the idea to describeessential characteristics of technical systems from the point of theirquality of service. Reliability as the indicator of technical systembehaviors in operation, and maintainability as the indicator of techni-cal system behaviors during the period of failures can be stated as themost recognizable concepts. These two concepts and their implemen-tations had the most progressive development. The concept of effec-tiveness was defined later in attempt to describe simultaneouslytechnicalsystemsbehaviorsinoperationandinperiodsoffailure.Thisconceptconsideredreliabilityandavailabilityperformances,aswellasfunctionalityofproposedtechnicalsystemdesign(Papic&Milovanovic,2007). In other words, the effectiveness of a technical system can bearticulatedasprobabilitythatatechnicalsystemwillbeputinfunc-tionsuccessfullyand performrequiredcriterionfunctionwithinthelimits of allowed discrepancies for given time period and given sur-rounding conditions. Although in the same spirit, some authors havedefined effectiveness somewhat differently. In (Ebramhimipour &Suzuki, 2006) effectiveness was defined as overall indicator whichcontains efficiency, reliability and availability. These two citeddefinitionsinclude parallelconcerningofreliabilityandavailability,althoughavailabilityincludesreliabilityandmaintainability(Ivezic ,Tanasijevic ,&Ignjatovic ,2008).Thereforeitcanbeagreeduponthatthe effectivenessis influenced by reliability, maintainability and func-tionality. Reliability is defined as characteristic of a system to contin-uouslykeepoperatingabilitywithinthelimitsofalloweddiscrepancies0957-4174/$ - see front matter ? 2012 Elsevier Ltd. All rights reserved.doi:10.1016/j.eswa.2012.02.013Corresponding author.E-mail address: tanrgf.bg.ac.rs (M. Tanasijevic ).Expert Systems with Applications 39 (2012) 89408946Contents lists available at SciVerse ScienceDirectExpert Systems with Applicationsjournal homepage: the calendar period of time; maintainability as capacity of thesystemforpreventionandfindingfailuresanddamages,forrenewingoperating ability and functionality through technical attending andrepairs; and functionality as the degree of fulfilling the functionalrequirements, namely the adjustment to environment, or more pre-cisely to the conditions in which the system operates.In the case of monitoring reliability and maintainability it iscommon to monitor the time picture of state (Fig. 1) according towhich the functions of reliability and maintainability can be deter-mined, as well as the mean time in operation and the mean time infailure.The main problem that occurs in forming the time picture ofstate is data monitoring and recording. In real conditions the ma-chines should be connected to information system which wouldprecisely record each failure, duration and procedure of repair. Thisis usually expensive and improvised monitoring of the machineperformance, namely of its shut downs, is imprecise. Moreover,statistical data processing provided by the time picture of the staterequires that all machines work under equal conditions, which isdifficult to achieve. As for the functionality of the technical system,there is no common way for its measuring and quantification. Thisis the reason why in this paper, in order to assess the effectiveness,expertise judgments of the employed in the working process of theanalyzedmachineswillbeused.Applicationofexpertisejudgments has been largely used in literature, primarily for dataprocessing and the assessment of the technical systems in termsof: risk (Li & Liao, 2007), safety (Wang 2000; Wang, Yang, & Sen,1995) or dependability (Ivezic et al., 2008; Tanasijevic, Ivezic,Ignjatovic, & Polovina, 2011). Expertise judgment is naturally givenin linguistic form. Thereby, as the logical mathematical andconceptual model for processing the expertise judgments, namelyfor calculating with linguistic descriptions, the fuzzy set theorywas used (Klir & Yuan, 1995; Zadeh, 1996). Application of fuzzysets today represents one of the most frequently used tools forsolving the problems in various areas of optimization (Huang,Gu, & Du, 2006) andidentification (Chan, 1996) regardingengineering problems. Cai (1996) presents the overview of variousapplication aspects of fuzzy methodology in systemfailureengineering, which is a problem close to effectiveness assessment.Application of fuzzy logic theory and experts systems (Liao,2011; Liebowitz, 1988) in general is also used for solving theoptimizations problems from area of agro machinery. In article(Rohani, Abbaspour-Fard, & Abdolahpour, 2011) on the base ofneural networks application, failures on tractors were predicted.In article (Ye, Yu, & Zhao, 2010) fuzzy mathematics, reliabilitytheory and multi-objective optimization technology were appliedto design tractors final transmission. Predictability of machinedowntimes and reliability, significantly depends on its effective-ness of technical systems.The idea of this paper is to establish the model for effectivenessdetermination according to fuzzy sets theory utilization. Therebythe fuzzy sets were used to analyze reliability, maintainabilityand functionality performances (partial indicators of effectiveness)as well as for their integration into effectiveness. In this way effec-tive model for the quality assessment of the technical systems intheir working conditions is obtained. The model can be used as cri-teria for decision making related to any procedure in purchasing,operation or maintenance of the system, for prediction of repairand maintenance costs. Quality and functionality of the proposedmodel is shown in effectiveness determination of agriculturalmachinery, precisely tractors.2. Effectiveness performance assessment based on fuzzy setstheoryMathematical and conceptual model of effectiveness assess-ment is practically summarized in two steps: fuzzy propositionof effectiveness partial indicators; and fuzzy composition of men-tioned indicators into one synthesized. Fuzzy proposition is pro-cedure for representing the statement that includes linguisticvariables based on available information about considered techni-cal system. In that sense it is necessary to define the names of lin-guistic variables that represent different grades of effectiveness ofconsidered technical system and define the fuzzy sets that describethe mentioned variables. Composition is a model that providesstructure of indicators influences to the effectiveness performance.2.1. Fuzzy model of problem solvingThe first step in the creation of fuzzy model for effectiveness (E)assessment is defining linguistic variables related to itself and toreliability (R), maintainability (M) and functionality (F). Regardingnumber of linguistic variables, it can be found that seven is themaximal number of rationally recognizable expressions that hu-man can simultaneously identify (Wang et al., 1995). However,for identification of considered characteristics even the smallernumber of variables can be useful because flexibility of fuzzy setsto include transition phenomena as experts judgments commonlyis (Ivezic et al., 2008). According to the above, five linguistic vari-ables for representing effectiveness performances are included:poor, adequate, average, good and excellent. Form of these linguis-tic variables is given as appropriate triangular fuzzy sets (Klir &Yuan, 1995), and they are presented in Fig. 2.In Fig. 2, j = 1,.,5 practically represents measurement units ofeffectiveness.Thereby, partial indicators of effectiveness: R, M and F, pre-sented as membership functionl:lR l1R;.;l5R;lM l1M;.;l5M;lF l1F;.;l5F1In the next step, maxmin composition is performed on them. Maxmin composition, also called pessimistic, is often used in fuzzy alge-bra as a synthesis model (Ivezic et al., 2008; Tanasijevic et al., 2011;Wang et al., 1995; Wang 2000). The idea is to make overall assess-ment (E) equal to the partial virtual representative assessment. Thisassessment is identified as the best possible one between the worstpartial grades expected (R, M or F).It can be concluded that all elements of (R, M and F) that makethe E have equal influence on E, so that maxmin composition willbe used, which in parallel way treats the partial ones onto theFig. 1. Time picture of state, t time spent in operation,s time in failure, h time of planned shut down due to preventive maintenance.R. Miodragovic et al./Expert Systems with Applications 39 (2012) 894089468941synthetic indicator. In literature (Ivezic et al., 2008; Wang et al.,1995) maxmin compositions which by using operators ANDand OR provide an advantage to certain elements over the othersin the process of synthesis, are also used.Precisely, if we look at three partial indicators, namely theirmembership function (1), it is possible to make C = j3= 53combina-tions of their membership functions. Each of these combinationsrepresents one possible synthesis effectiveness assessment (E).E lj1;.;5R;lj1;.;5M;.;lj1;2;.5Fhi;for all c 1 to C2If we take into account only values iflj1;.;5R;M;F 0, we get combina-tions that are named outcomes (o = 1 to O, where O # C).Further, for each outcome its values are calculated (Xc). Theoutcome which would suit the combination c, it would be calcu-lated following the equations:XcPR;M;Ejhic33Finally, all of these outcomes are treated with maxmin composi-tion, as follows:(i) For each outcome search for the MINimum value oflR,M,Finvector Ec(2). The minimum which would suit the combina-tion o, it would be calculated following the equations:MIN0 minflj1;.;5R;lj1;.;5M.;lj1;.;5Fg;for all o 1 to O4(ii) Outcomes are grouped according to their valuesXc(3),namely the size of j.(iii) Find the MAXimum between previously identified mini-mums (i) for each group (ii) of outcomes. The maximumwhich would suit value of j, would be calculated followingthe equations:MAXj maxfMINog; for every j5E assessment of technical system is obtained in the form:lE MAXj1;.;MAXj5 l1E;.;l5E6This expression (6) is necessary to map back to the E fuzzy sets(Fig. 2). Best-fit (Wang et al., 1995), method is used for transforma-tion of E description (6) to form that defines grade of membershipto fuzzy sets: poor, adequate, average, good and excellent. This pro-cedure is recognized as identification. Best-fit method uses distance(d) between E obtained by maxmin composition (6) and each ofthe E expressions (according to Fig. 2), to represent the degree towhich E is confirmed to each of fuzzy sets of effectiveness (Fig. 2).diEj;Hi ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiX5j1ljE ?ljHj2vuut;j 1;.;5;Hi fexcellent;goodaverage;adequate;poorg7where is (according to Fig. 2):lexc.= (0,0,0,0.25,1);lgood= (0,0,0.25,1,0.25);laver.= (0,0.25,1,0.25,0);ladeq.= (0.25,1,0.25,0,0);lpoor= (1,0.25,0,0,0).The closerlE(6) is to the ith linguistic variable, the smaller diis.Distance diis equal to zero, iflE(6) is just the same as the ithexpression in terms of the membership functions. In such a case,E should not be evaluated to other expressions at all, due to theexclusiveness of these expressions.Suppose dimin(i = 1,.,5) is the smallest among the obtaineddistances for Ejand leta1,.,a5represent the reciprocals of the rel-ative distances (which is calculated as the ratio between corres-ponding distance di(7) and the mentioned values dimin). Then,aican be defined as follows:ai1di=dimin;i 1;.;58If di= 0 it follows thatai= 1 and the others are equal to zero. Then,aican be normalized by:biajP5m1aim;i 1;.;5X5i1bi 19Each birepresents the extent to which E belongs to the ith defined Eexpressions. It can be noted that if Eicompletely belongs to the ithexpression then biis equal to 1 and the others are equal to 0. Thus bjcould be viewed as a degree of confidence that Eibelongs to the ith Eexpressions. Final expression for E performance at the level of tech-nical system, have been obtained in the form (10)Eifbi1;poor;bi2;adequate;bi3;good;bi4;average;bi5;excellentg103. An illustrative exampleAs an illustrative example of evaluation of agriculture machin-ery effectiveness, the comparative analysis of three tractors A1B2,and C2is given in this article.In tractor A a 7.146 l engine LO4V TCD 2013 is installed. Thanksto the reserves of torque from 35%, the tractor is able to meet allthe requirements expected in the worst performing farming oper-ations in agriculture. Total tractor mass is 16,000 kg. According toOECD (CODE II) report maximum power measured at the PTO shaftis243 kWat2200 rpmwithspecificfuelconsumptionof198 g/kW h (ECE-R24). Maximum engine torque is 1482 Nm at en-gine regime of 1450 rpm. Transmission gear is vario continioustransmision. Linkage mechanism is a Category II/III with liftingforce of 11,800 daN.In tractors B2and C28.134 l engine 6081HRW37 JD is installed,with reserve torque of 40%, and this tractor was able to meet all therequirements expected in the worst performance of the farmingoperations in agriculture. Total tractor weight is 14,000 kg. Accord-ing to OECD (CODE II) report maximum power measured at thePTO shaft is 217 kW at 2002 rpm with specific fuel consumptionof 193 g/kW h (ECE-R24). Maximum torque is 1320 Nm at enginerevs of 1400 rpm. Transmission is AutoPower. Linkage mechanismis a Category II/III with lifting force of 10,790 daN.Both models have electronically controlled tractor engine andfuel supply system that meets the regulations on emissions.From the submitted technical characteristics of the tractor A, Band C it is seen that all three tractors are fully functional forFig. 2. Effectiveness fuzzy sets.1Tractor Fendt Vario 936.2Tractor John Deere 8520.8942R. Miodragovic et al./Expert Systems with Applications 39 (2012) 89408946performing difficult operations for different technologies of agri-cultural production. Tractors B and C have the same technical char-acteristics, and practice is the same type and model, except thatthe tractor B entered into operation in May 2007, a tractor C in June2007. A tractor on the experimental farm, which is the technicaldocumentation for the base model, comes into operation in July2009. The main task of maintaining agricultural techniques is toprovide functionality and reliability of machines. Maintenance ofall three tractors is done by machine shop owned by the user up-grade option.Ten engineers (analysts) working on maintenance and opera-tion of tractors were interviewed. Their evaluation of R, D and Fare given in Table 1.First, the effectiveness of tractor A is calculated. It can be seenthat the reliability was assessed as excellent by six out of ten ana-lysts (6/10 = 0.6), as average by three (0.3) and as good by one(0.1). In this way the assessment R is obtained in the form (11):R 0:6=exc; 0:3=good; 0:1=aver; 0=adeq; 0=poor11In the same way the assessments for M and F are obtained:M 0:4=exc; 0:4=good; 0:2=aver; 0=adeq; 0=poorF 0:5=exc; 0:5=good; 0=aver; 0=adeq; 0=poorIn the next step, these assessments are mapped on fuzzy sets (Fig. 1)in order to obtain assessment in the form (1). For example, Reliabil-ity in this example is determined as (11), where it is to linguisticvariable excellent joined weight 0.6. Thereby, fuzzy set excellentis defined as: Rexc= (1/0, 2/0, 3/0, 4/0.25, 5/1.0) (according toFig. 1). In this way the specific values of fuzzy set excellentRexc0.6= (1/(0 ? 0.6),2/(0 ? 0.6),3/(0 ? 0.6),4/(0.25 ? 0.6),5/(1.0 ? 0.6) are obtained. The remaining four linguistic variablesare treated in the same way. In the end for each j = 1,.,5 specificmembership functions (last row, Table 2) are added into the finalfuzzy form (1) of tractor A reliability:lRA 0;0:025;0:175;0:475;0:675In the same way, based on the questionnaire (Table 1) values formaintainability and functionality are obtained:lMA 0;0:05;0:3;0:55;0:5;lFA 0;0;0:125;0:625;0:62512These fuzzificated assessments (11) and (12) are necessary to syn-thesize into assessment of effectiveness, using maxmin logics. Inthis case it is possible to make C = 53= 125 combinations, out ofwhich the 48 outcomes. First outcome would be for combination2-2-3: E2-2-3= 0.025,0.05,0.125, where isX2-2-3= (2 + 2 + 3)/3 = 2(rounded as integer). Smallest value among the membership func-tions of this outcome is 0.025. Other outcomes and correspondingvalues ofXcare shown in Table 3. All these outcomes can begrouped around sizesX= 2, 3, 4 and 5.For example, for outcomeX= 5 it can be written:E4?5?5 0:475;0:5;0:625?;E5?4?5 0:675;0:55;0:625?;E5?5?4 0:675;0:5;0:625?;E5?5?5 0:675;0:5;0:625?Further, for each of them, minimum between membership functionis sought:Table 1Results of questionnaire.AnalystLinguistic variablesTractor ATractor BTractor CExcellentGoodAverageAdequatePoorExcellentGoodAverageAdequate