果園水果采摘升降平臺的設(shè)計(jì)

果園水果采摘升降平臺的設(shè)計(jì),果園水果采摘升降平臺的設(shè)計(jì),果園,水果,生果,瓜果,采摘,升降,平臺,設(shè)計(jì) 塔里木大學(xué)畢業(yè)論文（設(shè)計(jì)）任務(wù)書學(xué)院機(jī)械電氣化工程學(xué)院班級農(nóng)機(jī)12-2班學(xué)生姓名學(xué)號課題名稱果園水果采摘升降平臺的設(shè)計(jì)起止時(shí)間2012年03月01日2012 年 05月 28日（共 14 周）指導(dǎo)教師職稱副教授課題內(nèi)容 課題內(nèi)容主要是果園水果采摘升降平臺的設(shè)計(jì)，首先對果園水果采摘升降平臺總體進(jìn)行設(shè)計(jì)，主要對現(xiàn)有升降平臺改進(jìn)，進(jìn)而用CAD軟件進(jìn)行實(shí)體繪制，并對實(shí)體圖進(jìn)行分析計(jì)算，達(dá)到實(shí)體工作狀態(tài)的目的。擬定工作進(jìn)度（以周為單位）第1-2周 查閱相關(guān)文獻(xiàn)，撰寫開題報(bào)告。第3-4周 走訪周邊團(tuán)場專家、進(jìn)行調(diào)查，比較分析，決定最優(yōu)設(shè)計(jì)方案。第5-6周 根據(jù)工作要求，查閱相關(guān)手冊，對機(jī)器總體設(shè)計(jì)、布局。第7-10周 運(yùn)用AutoCAD軟件，設(shè)計(jì)零件圖，裝配圖，進(jìn)行數(shù)據(jù)處理。第11-12周 對實(shí)體圖進(jìn)行仿真。第13-14周 完成設(shè)計(jì)說明書。主要參考文獻(xiàn)1.仆炎主編. 機(jī)械傳動裝置設(shè)計(jì)手冊上冊M. 北京:機(jī)械工業(yè)出版社, 1999。2.濮良貴等.機(jī)械設(shè)計(jì).北京：高等教育出版社，2006。3.孫恒等.機(jī)械原理.北京：高等教育出版社，2006。4.左鍵民.液壓與氣壓傳動.北京：機(jī)械工業(yè)出版社，2008。5.章宏甲.液壓傳動.北京：機(jī)械工業(yè)出版社，2002。6.楊黎明.機(jī)械零件設(shè)計(jì)手冊.北京：國防工業(yè)出版社，1996。7.徐灝.機(jī)械設(shè)計(jì)手冊.北京：機(jī)械工業(yè)出版社，1995。8.劉新德.袖珍液壓氣動手冊.北京：機(jī)械工業(yè)出版社，2004。9.葉玉駒等.機(jī)械制圖手冊.北京：機(jī)械工業(yè)出版社，2008。10.成大先.機(jī)械設(shè)計(jì)手冊單行本液壓傳動.北京：化學(xué)工業(yè)出版社，2004。11.李壯云.中國機(jī)械設(shè)計(jì)大典5.南昌:江西科學(xué)技術(shù)出版社，2002。12.王昆等.機(jī)械設(shè)計(jì)課程設(shè)計(jì)手冊.北京：高等教育出版社，2004。13.周元康等.機(jī)械設(shè)計(jì)課程設(shè)計(jì).重慶：重慶大學(xué)出版社，2001。任務(wù)下達(dá)人（簽字） 年 月 日任務(wù)接受人意見任務(wù)接受人簽名 年 月 日注：1、此任務(wù)書由指導(dǎo)教師填寫，任務(wù)下達(dá)人為指導(dǎo)教師。2、此任務(wù)書須在學(xué)生畢業(yè)實(shí)踐環(huán)節(jié)開始前一周下達(dá)給學(xué)生本人。3、此任務(wù)書一式三份，一份留學(xué)院存檔，一份學(xué)生本人留存，一份指導(dǎo)教師留存。 12 屆畢業(yè)設(shè)計(jì)果園水果采摘升降平臺的設(shè)計(jì)設(shè)計(jì)說明書學(xué)生姓名 學(xué) 號 所屬學(xué)院 機(jī)械電氣化工程學(xué)院 專 業(yè) 農(nóng)業(yè)機(jī)械化及其自動化 班 級 12-2 指導(dǎo)教師 日 期 2012.6 塔里木大學(xué)教務(wù)處制2012屆畢業(yè)設(shè)計(jì)畢業(yè)設(shè)計(jì)（論文）開題報(bào)告題目 果園水果采摘升降平臺的設(shè)計(jì)學(xué)生姓名 學(xué) 號 所屬學(xué)院 機(jī)械電氣化工程學(xué)院 專 業(yè) 農(nóng)業(yè)機(jī)械化及其自動化 班 級 指導(dǎo)教師 日 期 2012.4 果園水果采摘升降平臺的設(shè)計(jì)開題報(bào)告一、 選題的依據(jù)及意義：果園水果采摘是農(nóng)業(yè)生產(chǎn)鏈中最耗時(shí)耗力的一個(gè)環(huán)節(jié),其成本高、季節(jié)性強(qiáng)、需要大量勞動力高強(qiáng)度的工作。但是由于工業(yè)生產(chǎn)的迅速發(fā)展分流了大量農(nóng)業(yè)勞動力以及人口老齡化加劇等原因,使得能夠從事農(nóng)業(yè)生產(chǎn)的勞動力越來越少,單靠原始的采摘方式越來越不適應(yīng)大量水果的采摘，加之水果的生長不固定，果樹的分散性，使水果采摘存在采摘困難以及部分無法采摘等問題。隨著當(dāng)代機(jī)械制造業(yè)與液壓技術(shù)的不斷發(fā)展，社會生產(chǎn)對生產(chǎn)率的要求也越來越高，因此，在農(nóng)業(yè)機(jī)械化的發(fā)展中，具有結(jié)構(gòu)緊湊，操作方便，升降平穩(wěn)等優(yōu)點(diǎn)的果園水果液壓升降機(jī)起著極其重要的作用。果園水果采摘液壓升降平臺是一種新型的液壓升降機(jī)，主要由機(jī)械元件和液壓泵等組成。因此我們有必要對它進(jìn)行深入研究。本次畢業(yè)設(shè)計(jì)的題目來源于水果采摘第一道工序，所設(shè)計(jì)的產(chǎn)品具有實(shí)用價(jià)值，已經(jīng)有成熟產(chǎn)品生產(chǎn)。我們可以參考現(xiàn)有產(chǎn)品做出的改進(jìn)設(shè)計(jì)，使產(chǎn)品機(jī)構(gòu)更合理、更實(shí)用、更可靠。 畢業(yè)設(shè)計(jì)涉及的內(nèi)容比較多，它是基礎(chǔ)課、技術(shù)基礎(chǔ)課以及專業(yè)課的綜合，是在學(xué)完機(jī)械設(shè)計(jì)制造及其自動化專業(yè)的全部課程，并進(jìn)行了專業(yè)生產(chǎn)實(shí)習(xí)的基礎(chǔ)上進(jìn)行的，是我們對所學(xué)的所有課程的一次深入的綜合性的總復(fù)習(xí)，也是一次理論聯(lián)系實(shí)際的訓(xùn)練，因此，它在我們的四年大學(xué)生活中占有重要的地位。本次畢業(yè)設(shè)計(jì)使我們能綜合運(yùn)用機(jī)械設(shè)計(jì)課程和其他先修課程的知識，分析和解決機(jī)械設(shè)計(jì)問題，進(jìn)一步鞏固、加深和拓寬所學(xué)的知識。通過設(shè)計(jì)實(shí)踐，逐步樹立正確的設(shè)計(jì)思想，增強(qiáng)創(chuàng)新意識和競爭意識，熟悉掌握機(jī)械設(shè)計(jì)的一般規(guī)律，培養(yǎng)分析問題和及決問題的能力。通過設(shè)計(jì)計(jì)算、繪圖以及運(yùn)用技術(shù)標(biāo)準(zhǔn)、規(guī)范、設(shè)計(jì)手冊等有關(guān)資料，進(jìn)行全面的機(jī)械設(shè)計(jì)基本技能的訓(xùn)練。二、國內(nèi)外研究概況及發(fā)展趨勢：1、國內(nèi)外研究概況目前，我國水果采摘大部分單憑人工爬樹或使用梯子采摘，移動較為困難并存在安全問題，大大降低了采收效率。因水果的成熟期較短，采收效率低直接影響水果的品質(zhì)及貯藏。然而，在工廠用很多先進(jìn)的升降平臺，如固定式液壓裝卸平臺，折臂式升降平臺，移動式升降平臺等，對其進(jìn)行簡單改裝，使其適應(yīng)果園環(huán)境，有利于實(shí)現(xiàn)采收的方便性，安全性及及時(shí)性。液壓升降平臺的核心部件在于液壓提升設(shè)備,因此國內(nèi)外對液壓提升設(shè)備主要進(jìn)行動力分析和運(yùn)動分析，確定液壓缸的主要性能參數(shù)和主要尺寸。如液壓缸的推力速度，作用時(shí)間，內(nèi)徑，液壓升降機(jī)行程及活塞桿直徑等。體積大且沉重、不便拆裝、用途單一、價(jià)格高、長時(shí)間暴露在外面易老化腐蝕，造成無謂的損害，久后會使連接處漏水。它通常采用35、34號或無縫鋼管做成實(shí)心桿或空心桿，為了提高耐磨性的防銹蝕，目前國內(nèi)傳統(tǒng)工藝是表面鍍硬鉻（鍍層厚度0.020.05mm）并拋光，其表面粗糙度Ra為1.60.4m。由于鍍鉻對人、環(huán)境污染嚴(yán)重，屬國家環(huán)保線值項(xiàng)目，且鍍層不均勻，液壓提升設(shè)備的工作液壓提升設(shè)備其實(shí)也就是個(gè)最簡單的油缸了.通過手動增壓稈(液壓手動泵)使液壓油經(jīng)過一液壓提升設(shè)備是液壓缸的重要部件，由于鍍鉻對人、環(huán)境污染嚴(yán)重，屬國家環(huán)保線值項(xiàng)目，且鍍層不均勻，孔隙率高，容易起皮，鍍鉻費(fèi)用也比較高，不能滿足生產(chǎn)上的需要。2、發(fā)展趨勢隨著全球科學(xué)技術(shù)的迅猛發(fā)展，世界液壓升降臺工業(yè)相繼發(fā)生了一系列重大的技術(shù)革命，極大地提高了勞動生產(chǎn)率和產(chǎn)品質(zhì)量，擴(kuò)大了生產(chǎn)規(guī)模，降低了產(chǎn)品熱耗、能耗，有效控制了煙塵、粉塵、有害氣體的排放，由此引發(fā)了世界液壓技術(shù)工業(yè)快速發(fā)展，解決了全球?qū)σ簤寒a(chǎn)品的巨大需求。在最近20年，世界液壓工業(yè)新技術(shù)絕大部分是在上世紀(jì)幾大創(chuàng)新技術(shù)的基礎(chǔ)上開發(fā)或發(fā)展的，這些新技術(shù)包括降低熱耗、提高自動化程度、擴(kuò)大生產(chǎn)規(guī)模、利用廢物、環(huán)境保護(hù)、產(chǎn)品深加工等方面。其中玻璃鋼/復(fù)合材料的技術(shù)有著良好的發(fā)展前景，就是要大力開拓玻璃鋼/復(fù)合材料的應(yīng)用范圍，不斷提高先進(jìn)性能。此外，隨著人們生活水平的提高，建筑面積不段增加，像車間、倉庫等面積小又急需節(jié)省人力資源，提高勞動效率高，減少噪音和污染的場所，腳踏式液壓升降平臺車應(yīng)運(yùn)而生。國內(nèi)外研究人員正針對這些場所，根據(jù)人們的不同需要在不斷的完善升降平臺車的結(jié)構(gòu)性能，改變體積的大??！研發(fā)出能夠更加實(shí)現(xiàn)重物的平穩(wěn)升降、節(jié)省人力、占用空間小、安全可靠并能迅速地對承載物重量的改變做出反應(yīng)的液壓升降平臺車。三、研究內(nèi)容及實(shí)驗(yàn)方案： 1、研究內(nèi)容: 首先對液壓升降技術(shù)參數(shù)進(jìn)行分析研究，結(jié)合具體實(shí)例，對機(jī)構(gòu)中兩種液壓缸布置方式分析比較，并根據(jù)要求對液壓傳動系統(tǒng)個(gè)部分進(jìn)行設(shè)計(jì)計(jì)算最終確定液壓執(zhí)行元件-液壓缸，通過對叉桿的各項(xiàng)受力分析確定臺板與叉桿的載荷要求，最終完成液壓升降臺的設(shè)計(jì)要求。四、目標(biāo)、主要特色及工作進(jìn)度1、目 標(biāo)：根據(jù)老師給定的數(shù)據(jù)和技術(shù)要求，結(jié)合自己所學(xué)知識，運(yùn)用計(jì)算機(jī)CAD軟件等繪圖手段設(shè)計(jì)一款經(jīng)濟(jì)實(shí)用、安全可靠的液壓升降臺。2、工作進(jìn)度：(1)第1-2周 查閱相關(guān)文獻(xiàn)，撰寫開題報(bào)告。(2)第3-4周 總體方案設(shè)計(jì) (3)第58周 根據(jù)工作要求，查閱相關(guān)手冊，對各部分機(jī)構(gòu)設(shè)計(jì)、計(jì)算，畫草圖。 (4)第9-10周成本核算，從工藝性能，經(jīng)濟(jì)性能，實(shí)用性能等方面對產(chǎn)品進(jìn)行綜合評價(jià)，校核，修正。 (5)第11-12周 撰寫畢業(yè)設(shè)計(jì)論文說明書 五、參考文獻(xiàn)1 機(jī)械設(shè)計(jì)，濮良貴，紀(jì)名剛主編。第八版。北京：高等教育出版社，2006。2 機(jī)械原理，孫恒，陳作模主編。第七版。北京：高等教育出版社，2006。3 液壓與氣壓傳動，左鍵民主編。第4版。北京：機(jī)械工業(yè)出版社，2008。4 機(jī)械零件設(shè)計(jì)手冊，楊黎明主編。北京：國防工業(yè)出版社，1996。5 機(jī)械設(shè)計(jì)手冊，徐灝主編。北京：機(jī)械工業(yè)出版社，1995.12。6 機(jī)械設(shè)計(jì)課程設(shè)計(jì)手冊，王昆等主編。北京：高等教育出版社，2004。7 機(jī)械設(shè)計(jì)課程設(shè)計(jì)，周元康、林昌華、張海兵主編。重慶：重慶大學(xué)出版社，2001。8 機(jī)械制造專業(yè)畢業(yè)設(shè)計(jì)指導(dǎo)與范例，何慶主編。北京：化學(xué)工業(yè)出版社，2008.9 機(jī)械專業(yè)畢業(yè)設(shè)計(jì)寶典，孫波主編。西安：西安電子科技大學(xué)出版社，2008.10 理工類學(xué)生專業(yè)論文導(dǎo)寫，歐陽周，劉道德主編。長沙：中南工業(yè)大學(xué)出版社，2000 11 液壓傳動，章宏甲主編。北京：機(jī)械工業(yè)出版社，2002 塔里木大學(xué)畢業(yè)設(shè)計(jì)目 錄1緒論11.1課題研究的目的及意義11.2國內(nèi)外研究概況及發(fā)展趨勢11.3本課題研究內(nèi)容12果園水果采摘升降平臺的設(shè)計(jì)的總機(jī)設(shè)計(jì)12.1總體方案的分析比較和確定12.2液壓升降平臺車的結(jié)構(gòu)及運(yùn)動原理23升降臺尺寸初步分析計(jì)算33.1升降臺高度的計(jì)算33.2相關(guān)角度的計(jì)算34升降臺受力及力矩分析34.1整體受力分析圖34.2外鉸架受力分析圖44.3內(nèi)鉸架受力分析圖44.4力和力矩的分析計(jì)算54.5液壓缸受力分析55液壓系統(tǒng)的分析75.1 受載分析75.2 液壓系統(tǒng)方案設(shè)計(jì)76液壓缸液壓泵具體選型86.1液壓缸的選擇86.2液壓泵設(shè)計(jì)計(jì)算及選型86.3油量的校核87各構(gòu)件參數(shù)設(shè)計(jì)87.1內(nèi)、外鉸架材料及設(shè)計(jì)尺寸選擇87.2滾道材料及設(shè)計(jì)尺寸選擇87.3升降工作臺材料及設(shè)計(jì)尺寸選擇87.4底座材料及設(shè)計(jì)尺寸選擇88應(yīng)力計(jì)算及強(qiáng)度校核88.1 內(nèi)、外鉸架力的分解88.2 外鉸架軸力圖、剪力圖和彎矩圖分析98.3內(nèi)鉸架軸力圖、剪力圖和彎矩圖分析108.4 鉸架應(yīng)力強(qiáng)度校核11致 謝13參考文獻(xiàn)141緒論1.1課題研究的目的及意義1.1.1果園水果采摘液壓升降平臺設(shè)計(jì)的目的 1、理論目的：綜合運(yùn)用機(jī)械設(shè)計(jì)課程、液壓技術(shù)，材料力學(xué)及其他與相關(guān)課程的理論知識和生產(chǎn)實(shí)際，進(jìn)行液壓升降臺設(shè)計(jì)實(shí)踐，使理論知識和生產(chǎn)實(shí)踐緊密結(jié)合起來，并得到進(jìn)一步的鞏固和提高。 2、實(shí)踐目的：在設(shè)計(jì)實(shí)踐中學(xué)習(xí)和掌握通用液壓元件，尤其是各類標(biāo)準(zhǔn)元件的選用原則和回路的組合方法，培養(yǎng)設(shè)計(jì)技能，提高分析和解決生產(chǎn)實(shí)際問題的能力，為今后的設(shè)計(jì)制造工作打好的基礎(chǔ)。1.1.2果園水果采摘升降平臺車設(shè)計(jì)的意義 隨著當(dāng)代農(nóng)業(yè)機(jī)械化及其自動化的不斷發(fā)展，農(nóng)業(yè)生產(chǎn)對生產(chǎn)率的要求也越來越高，因此，在農(nóng)業(yè)機(jī)械化的發(fā)展中，具有結(jié)構(gòu)緊湊，操作方便，升降平穩(wěn)等優(yōu)點(diǎn)的果園水果液壓升降機(jī)起著極其重要的作用。果園水果采摘液壓升降平臺是一種新型的液壓升降機(jī)，主要由機(jī)械元件和液壓泵等組成,我們有必要對它進(jìn)行深入研究。本次畢業(yè)設(shè)計(jì)的題目來源于水果采摘第一道工序，所設(shè)計(jì)的產(chǎn)品具有實(shí)用價(jià)值，針對已有成熟產(chǎn)品的廣泛使用,分析其存在的優(yōu)缺點(diǎn)并對現(xiàn)有產(chǎn)品做出的改進(jìn)設(shè)計(jì)，使產(chǎn)品機(jī)構(gòu)更合理、更實(shí)用、更可靠。1.2國內(nèi)外研究概況及發(fā)展趨勢1.2.1研究現(xiàn)狀 目前，我國水果采摘大部分單憑人工爬樹或使用梯子采摘，移動較為困難并存在安全問題，大大降低了采收效率。因水果的成熟期較短，采收效率低直接影響水果的品質(zhì)及貯藏。然而，在工廠用很多先進(jìn)的升降平臺，如固定式液壓裝卸平臺，折臂式升降平臺，移動式升降平臺等，對其進(jìn)行簡單改裝，使其適應(yīng)果園環(huán)境，有利于實(shí)現(xiàn)采收的方便性，安全性及及時(shí)性。升降平臺的核心部件在于液壓提升設(shè)備。因此，國內(nèi)外對液壓提升設(shè)備主要進(jìn)行動力分析和運(yùn)動分析，確定液壓缸的主要性能參數(shù)和主要尺寸。如液壓缸的推力速度，作用時(shí)間，內(nèi)徑，液壓升降機(jī)行程及活塞桿直徑等。1.2.2發(fā)展趨勢 隨著全球科學(xué)技術(shù)的迅猛發(fā)展，世界液壓升降臺工業(yè)相繼發(fā)生了一系列重大的技術(shù)革命，極大地提高了勞動生產(chǎn)率和產(chǎn)品質(zhì)量，擴(kuò)大了生產(chǎn)規(guī)模，降低了產(chǎn)品熱耗、能耗，有效控制了煙塵、粉塵、有害氣體的排放，由此引發(fā)了世界液壓技術(shù)工業(yè)快速發(fā)展，解決了全球?qū)σ簤寒a(chǎn)品的巨大需求。在最近20年，世界液壓工業(yè)新技術(shù)絕大部分是在上世紀(jì)幾大創(chuàng)新技術(shù)的基礎(chǔ)上開發(fā)或發(fā)展的，這些新技術(shù)包括降低熱耗、提高自動化程度、擴(kuò)大生產(chǎn)規(guī)模、利用廢物、環(huán)境保護(hù)、產(chǎn)品深加工等方面。其中玻璃鋼復(fù)合材料的技術(shù)有著良好的發(fā)展前景，就是要大力開拓玻璃鋼復(fù)合材料的應(yīng)用范圍，不斷提高先進(jìn)性能。此外，隨著人們生活水平的提高，建筑面積不段增加，像車間、倉庫等面積小又急需節(jié)省人力資源，提高勞動效率高，減少噪音和污染的場所，液壓升降平臺車應(yīng)運(yùn)而生。國內(nèi)外研究人員正針對這些場所，根據(jù)人們的不同需要在不斷的完善升降平臺車的結(jié)構(gòu)性能，改變體積的大小！研發(fā)出能夠更加實(shí)現(xiàn)重物的平穩(wěn)升降、節(jié)省人力、占用空間小、安全可靠并能迅速地對承載物重量的改變做出反應(yīng)的液壓升降平臺車。1.3本課題研究內(nèi)容 首先對液壓升降技術(shù)參數(shù)進(jìn)行分析研究，結(jié)合具體實(shí)例，對機(jī)構(gòu)中兩種液壓缸布置方式分析比較，并根據(jù)要求對液壓傳動系統(tǒng)個(gè)部分進(jìn)行設(shè)計(jì)計(jì)算最終確定液壓執(zhí)行元件-液壓缸，通過對叉桿的各項(xiàng)受力分析確定臺板與叉桿的載荷要求，最終完成液壓升降臺的設(shè)計(jì)要求。2果園水果采摘升降平臺的設(shè)計(jì)的總機(jī)設(shè)計(jì)2.1總體方案的分析比較和確定 經(jīng)過多方面考慮，對液壓升降平臺車的設(shè)計(jì)初擬定兩種方案方案一分析：如圖2-1所示，液壓升降臺采用的液壓缸兩端都可在一定空間內(nèi)自由活動，這樣一來對液壓缸易受到徑向剪切力和較大彎矩，從而對其壓桿穩(wěn)定性要求很高。從外形結(jié)構(gòu)上來說，尺寸設(shè)計(jì)計(jì)算和力的計(jì)算都很復(fù)雜，而且要滿足升降臺升降時(shí)的最大最小高度，需要較大的液壓缸行程。此外從安全方面考慮，與液壓缸上端作用點(diǎn)相連接的肋板部分作用在連接鉸架的軸上，則軸對該處鉸架截面作用力將很大，則該截面可能成為危險(xiǎn)截面。且當(dāng)液壓缸活塞到底部時(shí)，升降臺還可能將有較大高度，不能滿足升降臺的設(shè)計(jì)要求。 圖2-1 液壓升降平臺方案一 方案二分析：如圖2-2所示，該方案和方案一不同之處之一在于，液壓缸一端通過軸固定在底座上，另一端通過肋板固定在鉸架上，這樣液壓缸的一端繞另一端在某個(gè)較小角度內(nèi)旋轉(zhuǎn)，能保證液壓缸具有較好的壓桿穩(wěn)定性，而且液壓缸作用在鉸架的實(shí)心截面處，使鉸架受力分配較均勻。另外，在此方案中，液壓缸的作用點(diǎn)較低，那么的液壓缸的行程只需變化很小，便載物臺就可以實(shí)現(xiàn)較大幅度的升降，易于滿足設(shè)計(jì)要求，因此它能節(jié)省工作人員的體力，提高工作人員的工作效率。通過以上的方案分析，果園水果采摘液壓升降平臺采用方案二設(shè)計(jì)。圖2-2 液壓升降平臺方案一2.2液壓升降平臺車的結(jié)構(gòu)及運(yùn)動原理 液壓升降平臺主要由動力源和機(jī)架兩部分組成，動力源部分主要由液壓泵和單作用液壓缸組成，機(jī)架部分由工作平臺，內(nèi)外剪式鉸架板和底座導(dǎo)軌槽，支撐板等構(gòu)件組成(如圖2-3所示)。 圖2-3 液壓升降平臺車結(jié)構(gòu) 1鏈輪鋼架，2滑輪，3液壓升縮機(jī)構(gòu)，4內(nèi)腳架，5載物平臺， 6鉸接軸7外鉸架，8液壓缸轉(zhuǎn)軸，9肋板，10導(dǎo)軌，11底座 果園水果采摘液壓升降平臺的運(yùn)動原理如下所述： 首先，升降平臺的升降是通過液壓缸的伸縮運(yùn)動來實(shí)現(xiàn)地的。液壓缸一端通過軸和兩肋板與外鉸架相連。另一端通過軸固定在底座導(dǎo)軌槽的中部位置；其次，內(nèi)、外鉸架與導(dǎo)軌槽連接的方式為：圖示鉸架右端通過安裝了軸承的滾輪與上下導(dǎo)軌槽相連接，圖示鉸架左端通過鉸支連接固定在上下導(dǎo)軌槽左部；液壓泵經(jīng)過油管與液壓缸相連，則當(dāng)手拉液壓泵滑輪時(shí)，油壓將頂起液壓缸使柱塞伸出，當(dāng)卸荷時(shí)，重物的重力將使肋板壓縮柱塞，使柱塞回縮進(jìn)去。由前述的連接方式得，與外鉸架7右側(cè)，內(nèi)鉸架4右側(cè)相連接的滾輪將左右滾動，從而工作平臺將上升或下降，起到升降貨物的作用。3 升降臺尺寸初步分析計(jì)算3.1升降臺高度的計(jì)算 （1）、設(shè)計(jì)升降臺最大高度為950至1050mm之間，可取=1000mm左右，而升降臺最小高度設(shè)計(jì)為=435mm； （2）、選用滾輪時(shí)，因滾輪為標(biāo)準(zhǔn)件，可選取其直徑為250mm，則輪子底部至升降臺底座支撐板底部的距離，即滾輪機(jī)構(gòu)總體高度可選為t=300mm； （3)、試選上端導(dǎo)軌槽整體高度=50mm,底座導(dǎo)軌槽整體厚度=60mm,則未考慮平臺厚度的情況下，上端導(dǎo)軌槽固定鉸支中心與底座固定鉸支中心的距離為：a升降臺處于最大高度時(shí)，=-（t+）=1000-(200+)=645mmb升降臺處于最小高度時(shí)，=-（t+）=435-(200+)=80mm3.2相關(guān)角度的計(jì)算 若設(shè)液壓缸作用點(diǎn)中心與平臺底部距離為=10mm,則底座固定鉸支中心至液壓缸作用點(diǎn)中心的垂直距離為：g=-=180-10-=145mm。 由升降平臺尺寸為1010520mm,則可設(shè)升降臺處于最低高度時(shí)，底座固定鉸支中心與活動鉸支中心兩點(diǎn)距離為d=850mm。則tan=0.2117 =則2L=869mm，從而sin=0.8575 =以上2L- 鉸架長度；- 升降臺最低高度時(shí)鉸架中心線與底座導(dǎo)軌中心線夾角；- 升降臺最大高度時(shí)鉸架中心線與底座導(dǎo)軌中心線夾角； 此時(shí)升降臺處于最大高度時(shí)有，底座固定鉸支中心與活動鉸支中心兩點(diǎn)距離為e=448mm=435mm。這說明當(dāng)升降臺處于最大高度時(shí)，所承受重物作用中心仍介于平臺固定鉸支中心與活動鉸支中心之間，使得平臺傾覆的可能性極小，滿足穩(wěn)定性要求。4 升降臺受力及力矩分析4.1整體受力分析圖 升降臺在整體受力如圖4-1，圖4-1 整體受力分析圖4.2外鉸架受力分析圖外鉸架L1受力分析如圖4-2，圖4-2 外鉸架受力分析圖圖中： , ; , ;4.3內(nèi)鉸架受力分析圖 內(nèi)鉸架L2受力分析如圖4-3，圖4-3 內(nèi)鉸架受力分析圖 圖中; , ; ; 以上了圖中所示力的方向皆為事先假設(shè)力的方向，其中規(guī)定水平方向（x方向）向上為正，向下為負(fù)；豎直方向（y方向）向右為正，向左為負(fù)。4.4力和力矩的分析計(jì)算4.4.1鉸架上端鉸支受力先忽略平臺自重，則由上圖因?yàn)椋?所以 而 （令，且有，為軸承滾輪與平臺導(dǎo)軌槽間的摩擦系數(shù)） ，則至此能計(jì)算出 、 、 、4.4.2整體受力分析計(jì)算 對平臺，重物及兩鉸架組成的整體進(jìn)行受力分析：（4.1） =0 =0 （1） =0 （2）4.4.3內(nèi)、外鉸架單獨(dú)受力分析 對L1單獨(dú)進(jìn)行受力平衡分析： =0 =0 （3） =0 =0 （4） 由（）、（）得 （5） 由（）、（）得 （6） . 對L2單獨(dú)進(jìn)行受力平衡分析： =0 =0 （7） =0 =0 （8）4.4.4力矩平衡分析 若規(guī)定逆時(shí)針為正，順時(shí)針為負(fù)，則對L1的c點(diǎn)的轉(zhuǎn)矩平衡得： =0 =0 （a)對L2有： （1），d點(diǎn)的轉(zhuǎn)矩平衡得： =0 =0 (b) （2），o點(diǎn)的轉(zhuǎn)矩平衡得： =0 =0 (c) =0 (d)又因?yàn)?軸承滾輪與底座導(dǎo)軌槽間的摩擦系數(shù)4.5液壓缸受力分析 4.5.1液壓缸受力公式的導(dǎo)出 由（c），（d）兩式得： 則至此能算出由上(5) 、(6)式分別可得： (e) =- （f） 將以上（e）、（f）式代入至（a）式得： F= = （g） 至此可算出力F，由于這些力是按對稱鉸架的一邊來考慮的，所以F為鉸架與底座成時(shí)液壓缸所承受的一半力的大小。則T=2F=其中：T-液壓缸受力大小4.5.2液壓缸最大受力時(shí)數(shù)值及角度計(jì)算 分析液壓缸產(chǎn)生最大力時(shí)，鉸架與底座所成角度大小 根據(jù)上面一系列的式子有，當(dāng)為不同大小時(shí)，對應(yīng)各鉸支點(diǎn)受力大小不同，從而液壓缸受力大小相應(yīng)不同?，F(xiàn)根據(jù)以上所列式子將部分關(guān)鍵數(shù)據(jù)輸入如下表4-1, 表 4-1 關(guān)鍵數(shù)據(jù)計(jì)算121824303642485459-24.5-24.4-24.4-24.4-24.3-24.3-24.2-24.2-24.12447.72375.22268.92122.01923.61657.11295.8794.4212.312.212.613.113.814.816.117.920.423.21223.61258.41310.11382.01479.41610.51788.72036.22322.864.887.6106.8122.9136.3147.1155.3161.0163.8305.0270.0239.8212.9187.6163.3139.8116.998.428.3529.4029.9530.0729.8429.3228.5527.5726.62435435435435435435435435435(N)206351939418310172841625315170139971270511517此外經(jīng)過更精確的計(jì)算得，液壓缸受力曲線圖如下圖4-4，圖4-4 液壓缸受力曲線圖 由上圖得，當(dāng)升降臺處于最低位置，即 =時(shí)，液壓缸受力最大，此時(shí)有有 T = 20635 N，考慮到工作平臺，工作平臺導(dǎo)軌槽，內(nèi)、外鉸架等的重量，經(jīng)咨詢，可取一系數(shù)=1.3，則液壓缸所受最大壓力為 = T= 20635 1.3 =26825.5 26826N 5 液壓系統(tǒng)的分析5.1 受載分析 該液壓升降臺的工作循環(huán)過程是：當(dāng)工作平臺處于最低位置時(shí)，手拉液壓升降機(jī)構(gòu)，升降臺升起，當(dāng)?shù)竭_(dá)最大高度時(shí)，升降臺停止上升，液壓系統(tǒng)進(jìn)入保壓階段；在升降臺上升的過程中，升降臺的傾角不斷地發(fā)生變化；升降臺開始下降，下降到最低點(diǎn)停止運(yùn)動，至此升降臺一個(gè)工作循環(huán)結(jié)束。在升降臺的整個(gè)工作循環(huán)過程中，在最低位置時(shí)液壓缸推力最大。隨著上平臺高度的增加，液壓缸的推力將逐漸減小。5.2 液壓系統(tǒng)方案設(shè)計(jì)5.2.1設(shè)計(jì)要求 結(jié)合設(shè)計(jì)要求，液壓升降平臺車的動力元件為手動式液壓泵，執(zhí)行元件為單作用液壓缸，其中手動液壓泵自帶油箱和卸荷閥，其內(nèi)部已有一部分液壓回路，原理如下：1， 當(dāng)要使工作平臺上升時(shí)，換向閥7左位接通，液壓泵3，1中油液進(jìn)入液壓缸下端，從而將液壓缸活塞頂出，平臺上升。2，當(dāng)要使工作平臺下降時(shí)，換向閥7右位接通，液壓缸6中的油液因重物產(chǎn)生的壓力而被壓出，經(jīng)由換向閥和節(jié)流閥流回油箱，節(jié)流閥8則控制油液的流速，從而使升降臺能緩慢卸載。5.2.2 液壓系統(tǒng)原理圖綜上所述，只需用油管將液壓泵出油口連接至液壓缸的進(jìn)油口即可組一完整的液壓回路，如圖5-1所示，圖5-1 液壓系統(tǒng)原理圖1油箱 ，2單向閥 ，3手動液壓泵 ，4單向閥 ，5溢流閥 ，6液壓缸，7手動換向閥 ，8節(jié)流閥 其中1、2、3、4、5、7、8都集中在液壓泵中6液壓缸液壓泵具體選型6.1液壓缸的選擇 由以上計(jì)算得出：液壓升降平臺車平臺處于最低高度，即 =時(shí)，液壓缸受力最大，此時(shí)液壓缸所受的力是= 26826 N。選擇缸徑為的液壓缸，其所能提供的最大推力為= 31420 N。其輸出壓力位700kgf/cm2，儲油量為1升，重量為12kg;此外液壓泵配有1m高壓油管/接頭。6.2液壓泵設(shè)計(jì)計(jì)算及選型 由于液壓缸承受的最大壓力為26826 N, 所以腳液壓泵至少要提供26826 N的力，根據(jù)以上要求選擇油壓泵F-1000型，其外形尺寸為Lbh=530160200mm。6.3油量的校核 由上得液壓缸需滿足的行程為180mm，而液壓缸直徑為50mm，則當(dāng)升降臺達(dá)最高位置時(shí)液壓缸內(nèi)儲油儲油=18010 = 0.353 L。 此外，此時(shí)油管中也儲存有一定的油量，而液壓缸所配油管為1m，內(nèi)徑為20mm，則油管儲油量為=10 = 0.314 L。則液壓缸所需出油量至少應(yīng)為= + =0.353+0.314 = 0.667L ，小于液壓缸而儲油量1L，故液壓缸儲油量足夠，滿足要求。7 各構(gòu)件參數(shù)設(shè)計(jì)7.1內(nèi)、外鉸架材料及設(shè)計(jì)尺寸選擇 內(nèi)外鉸架主要用于支撐升降臺面，是該液壓升降臺的重要組成構(gòu)件，因此其使用材料的性能至關(guān)重要，選擇型號為Q235的普通碳素鋼，初選實(shí)心處截面基本尺寸為3060mm，長度已確定約為870mm。7.2滾道材料及設(shè)計(jì)尺寸選擇 根據(jù)滾道的工作情況，并且考慮到滾輪的直徑，選擇熱軋普通槽鋼，型號為5。7.3升降工作臺材料及設(shè)計(jì)尺寸選擇 工作臺的，對于翻轉(zhuǎn)工作臺骨架，基本尺寸為LB=1010520，翻轉(zhuǎn)平臺面則用熱軋普通鋼板，公稱厚度為5mm。7.4底座材料及設(shè)計(jì)尺寸選擇 底座主要用于支撐作用，選用熱軋不等邊角鋼8 應(yīng)力計(jì)算及強(qiáng)度校核8.1 內(nèi)、外鉸架力的分解 首先外鉸架L1和內(nèi)較架L2受的力分解成沿鉸架方向（稱方向1）的力和垂直于該方向的方向（稱方向2）上的力 在上述分解合成力的過程中，由于豎直均很小，故這些力在1、2方向上的分解力可忽略不計(jì)。8.2 外鉸架軸力圖、剪力圖和彎矩圖分析圖8-1 外鉸架L1受力分析圖8-2 外鉸架L1軸力圖圖8-3 外鉸架L1縱向剪力圖圖8-4 外鉸架L1縱向彎矩圖 由上述圖有： 其中， 則外鉸架L1所受最大拉應(yīng)力為 或 ；其中=外鉸架L1所受最大壓應(yīng)力為 上式中、產(chǎn)生于液壓缸作用點(diǎn)截面處，產(chǎn)生于o點(diǎn)截面處。分別記為L1：拉、L1：壓、L1：拉。8.3內(nèi)鉸架軸力圖、剪力圖和彎矩圖分析 圖8-5 內(nèi)鉸架L2受力分析圖8-6 內(nèi)鉸架L2軸力圖圖8-7 內(nèi)鉸架L2縱向剪力圖圖8-8 內(nèi)鉸架L2縱向彎矩圖由上述圖有： ；其中 則內(nèi)鉸架L2所受最大拉應(yīng)力為 ； 其中內(nèi)鉸架L2所受最大壓應(yīng)力為 ； 其中上式中產(chǎn)生于o點(diǎn)處上半部分界面，產(chǎn)生于o點(diǎn)處下半部分界面。分別記為L2：拉、L2：壓。8.4 鉸架應(yīng)力強(qiáng)度校核8.4.1鉸架截面尺寸的確定 經(jīng)過精確計(jì)算和篩選，已選取內(nèi)外鉸架實(shí)心截面為3060mm，經(jīng)更詳細(xì)的計(jì)算發(fā)現(xiàn)，所選截面寬度太長，考慮到材料的節(jié)省和強(qiáng)度要求，現(xiàn)可將截面尺寸暫定為=2060mm。此外，在內(nèi)外鉸架相連接處，鉸架截面處應(yīng)加工有一孔，其直徑經(jīng)過計(jì)算可選取為=30mm。8.4.2鉸架截面應(yīng)力分析校核 結(jié)合8.3中內(nèi)容，可能產(chǎn)生的最大拉應(yīng)力為 L1：拉，L1：拉，L2：拉。可能產(chǎn)生的最大壓應(yīng)力為L1：壓，L2：壓。此外，在鉸架與水平線所成角度不同的時(shí)候，這些力又相應(yīng)地發(fā)生變化，結(jié)合相關(guān)數(shù)據(jù)得，其變化曲線如以下各圖所示，圖8-11 外鉸架L1中產(chǎn)生的可能最大拉應(yīng)力變化曲線圖8-12 外鉸架L1中產(chǎn)生的可能最大拉應(yīng)力變化曲線圖8-13 外鉸架L1中產(chǎn)生的可能最大壓應(yīng)力變化曲線圖8-14 內(nèi)鉸架L2中產(chǎn)生的可能最大拉應(yīng)力變化曲線圖8-15 內(nèi)鉸架L2中產(chǎn)生的可能最大壓應(yīng)力變化曲線 鉸架所選材料為Q235普通碳素鋼，其屈服極限=216235Mpa，若選取安全因數(shù)=2，則鉸架許用應(yīng)力=108117.5Mpa。 以上數(shù)據(jù)比較有,且,則校核得內(nèi)外鉸架所受應(yīng)力小于許用應(yīng)力，因此滿足內(nèi)、外鉸架支撐起貨物的強(qiáng)度要求而不至于鉸架斷裂，故所選用鉸架滿足設(shè)計(jì)要求。致 謝 經(jīng)過幾個(gè)月的努力，最終還是順利地完成了此次畢業(yè)設(shè)計(jì)。值此畢業(yè)設(shè)計(jì)論文完成之際，當(dāng)我再次回首這幾個(gè)月的經(jīng)歷時(shí)，真是頗有感慨，當(dāng)然最多的還是成就感。 通過本次畢業(yè)設(shè)計(jì)，我從中受益匪淺，不僅學(xué)會應(yīng)用大學(xué)里所學(xué)到的一些基礎(chǔ)知識去解決設(shè)計(jì)中遇到的問題，而且比較全面系統(tǒng)的理解了機(jī)械設(shè)計(jì)的一些設(shè)計(jì)方法和設(shè)計(jì)步驟，同時(shí)還認(rèn)識到作為一個(gè)設(shè)計(jì)人員必須具備的一些素質(zhì)。 在設(shè)計(jì)過程中也會遇到一些自己解決不了的問題，通過查閱相關(guān)資料文獻(xiàn)以及在王旭峰老師的悉心的指導(dǎo)和幫助下，問題都迎刃而解。 至此，我衷心地感謝我的指導(dǎo)老師王旭峰老師，在整個(gè)設(shè)計(jì)過程中他都給予了我悉心的指導(dǎo)和一次又一次的幫助。此外還要感謝和我一起做畢業(yè)設(shè)計(jì)的同學(xué)們，他們在本次設(shè)計(jì)中給予了我很大的幫助和支持。在設(shè)計(jì)的過程中，我也得到了許多同學(xué)的寶貴建議和不斷的啟發(fā)，和幾位課題相近的同學(xué)學(xué)習(xí)探討畢業(yè)設(shè)計(jì)時(shí)，我學(xué)到了不少的設(shè)計(jì)知識和創(chuàng)作方法，正是因?yàn)橛辛四銈兊膸椭抛屛也粌H學(xué)到了本次課題所涉及的新知識，更讓我感覺到了知識以外的東西。同時(shí)我還要感謝我的學(xué)校，在我們即將離校的最后一段時(shí)間里，能夠更多地讓我們學(xué)會一些實(shí)踐應(yīng)用知識，增加我們實(shí)踐操作和動手能力。再一次對我的母校表示感謝！ 最后，向在百忙中抽出時(shí)間對本論文進(jìn)行評審的各位老師表示衷心地感謝！謝謝你們的評審和教誨。四年的大學(xué)生活在這個(gè)季節(jié)即將劃上一個(gè)圓滿的句號，我將帶著你們的期盼和對自己的承諾再次起航。 參考文獻(xiàn)1.仆炎主編. 機(jī)械傳動裝置設(shè)計(jì)手冊上冊M. 北京:機(jī)械工業(yè)出版社, 1999。2.濮良貴等.機(jī)械設(shè)計(jì).北京：高等教育出版社，2006。3.孫恒等.機(jī)械原理.北京：高等教育出版社，2006。4.左鍵民.液壓與氣壓傳動.北京：機(jī)械工業(yè)出版社，2008。5.章宏甲.液壓傳動.北京：機(jī)械工業(yè)出版社，2002。6.楊黎明.機(jī)械零件設(shè)計(jì)手冊.北京：國防工業(yè)出版社，1996。7.徐灝.機(jī)械設(shè)計(jì)手冊.北京：機(jī)械工業(yè)出版社，1995。8.劉新德.袖珍液壓氣動手冊.北京：機(jī)械工業(yè)出版社，2004。9.葉玉駒等.機(jī)械制圖手冊.北京：機(jī)械工業(yè)出版社，2008。10.成大先.機(jī)械設(shè)計(jì)手冊單行本液壓傳動.北京：化學(xué)工業(yè)出版社，2004。11.李壯云.中國機(jī)械設(shè)計(jì)大典5.南昌:江西科學(xué)技術(shù)出版社，2002。12.王昆等.機(jī)械設(shè)計(jì)課程設(shè)計(jì)手冊.北京：高等教育出版社，2004。13.周元康等.機(jī)械設(shè)計(jì)課程設(shè)計(jì).重慶：重慶大學(xué)出版社，2001。14.何慶主編.機(jī)械制造專業(yè)畢業(yè)設(shè)計(jì)指導(dǎo)與范例.北京：化學(xué)工業(yè)出版社，2008。15.孫波.機(jī)械專業(yè)畢業(yè)設(shè)計(jì)寶典.西安：西安電子科技大學(xué)出版社，2008。16.歐陽周.理工類學(xué)生專業(yè)論文導(dǎo)寫.長沙：中南工業(yè)大學(xué)出版社，2000。 142012屆畢業(yè)生畢業(yè)論文（設(shè)計(jì)）資料學(xué)生姓名 學(xué) 號 所屬學(xué)院 機(jī)械電氣化工程學(xué)院 專 業(yè) 農(nóng)業(yè)機(jī)械化及其自動化班 級 12-2 塔里木大學(xué)教務(wù)處制前 言 本課題是農(nóng)業(yè)生產(chǎn)果園設(shè)施農(nóng)業(yè)等場所為方便水果的采摘而設(shè)計(jì)的液壓升降臺，是農(nóng)業(yè)機(jī)械化、自動化的必然產(chǎn)物。液壓升降平臺由優(yōu)質(zhì)鋼材、液壓泵、液壓缸、油管、軌道輪等有機(jī)組合而成，可以較為安全方便的進(jìn)行果園水果的修剪、采收等作業(yè)，改善勞動條件，提高勞動生產(chǎn)率和自動化水平。 本文所介紹的液壓升降臺最大載重量是500kg，該升降臺由兩部分組成：機(jī)構(gòu)本體和液壓系統(tǒng)。升降臺升降的操作控制是由一套液壓系統(tǒng)和液壓缸來完成的，而組合而成的液壓系統(tǒng)全部放在液壓油泵中。液壓泵和液壓缸都采用標(biāo)準(zhǔn)件，其中液壓缸為單作用液壓缸，本文首先通過支撐鉸架的受力分析詳細(xì)闡述了要提升起貨物，液壓缸所需承受的最大壓力。接著以之作為根據(jù)說明液壓泵、液壓缸等標(biāo)準(zhǔn)件的選用及型號，并介紹液壓泵內(nèi)部相關(guān)液壓系統(tǒng)原理以及對液壓泵儲油量進(jìn)行核算。此外在強(qiáng)度校核方面，主要通過材料力學(xué)知識對鉸架以及液壓缸作用兩端的軸進(jìn)行強(qiáng)度校核，最后對本升降臺進(jìn)行重量和成本核算。本畢業(yè)設(shè)計(jì)借鑒了大量的資料，采用了許多國家標(biāo)準(zhǔn)，充分的吸收了各行業(yè)的寶貴經(jīng)驗(yàn)。 systems. assessing the example of three tractors of the same category, which are exploited in climatic and soil conditions 1. Introduction for agricultural agricultural recognized careful technical, predicting ofcropproduction.Nowadays,theexistingmathematicaloptimiza- tion methods, supported by the high-performance computers, can efficiently resolve the optimization problems (Dette Duffy et al., 1994; Mileusnic, 2007; etc.). The formation of an optimal technical system in order to produce cheaper food, highly impacted reliability of tractors, its maintainability, and the functionality of the system. rounding conditions. Although in the same spirit, some authors have defined effectiveness somewhat differently. In (Ebramhimipour maintainabilityascapacityofthe systemforpreventionandfindingfailuresanddamages,forrenewing operating ability and functionality through technical attending and repairs; and functionality as the degree of fulfilling the functional requirements, 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 is common to monitor the time picture of state (Fig. 1) according to their 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 repair and maintenance costs. Quality and functionality of the proposed model is shown in effectiveness determination of agricultural machinery, precisely tractors. R. Miodragovic et al./Expert Systems with Applications 39 (2012) 89408946 8941 which the functions of reliability and maintainability can be deter- mined, as well as the mean time in operation and the mean time in failure. The main problem that occurs in forming the time picture of state is data monitoring and recording. In real conditions the ma- chines should be connected to information system which would precisely record each failure, duration and procedure of repair. This is usually expensive and improvised monitoring of the machine performance, namely of its shut downs, is imprecise. Moreover, statistical data processing provided by the time picture of the state requires that all machines work under equal conditions, which is difficult to achieve. As for the functionality of the technical system, there is no common way for its measuring and quantification. This is the reason why in this paper, in order to assess the effectiveness, expertise judgments of the employed in the working process of the analyzed machines will be used. Application of expertise judgments has been largely used in literature, primarily for data processing and the assessment of the technical systems in terms of: risk (Li Wang, Yang, Tanasijevic, Ivezic, Ignjatovic, Zadeh, 1996). Application of fuzzy sets today represents one of the most frequently used tools for solving the problems in various areas of optimization (Huang, Gu, Liebowitz, 1988) in general is also used for solving the optimizations problems from area of agro machinery. In article (Rohani, Abbaspour-Fard, and fuzzy composition of men- tioned indicators into one synthesized. Fuzzy proposition is pro- cedure for representing the statement that includes linguistic variables 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 of considered technical system and define the fuzzy sets that describe the mentioned variables. Composition is a model that provides structure of indicators influences to the effectiveness performance. 2.1. Fuzzy model of problem solving The first step in the creation of fuzzy model for effectiveness (E) assessment is defining linguistic variables related to itself and to reliability (R), maintainability (M) and functionality (F). Regarding number of linguistic variables, it can be found that seven is the maximal number of rationally recognizable expressions that hu- man can simultaneously identify (Wang et al., 1995). However, for identification of considered characteristics even the smaller number of variables can be useful because flexibility of fuzzy sets to include transition phenomena as experts judgments commonly is (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 .;l 5 R ; l M l 1 M ; .;l 5 M ; l F l 1 F ; .;l 5 F 1 In the next step, maxmin composition is performed on them. Max min 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. This assessment is identified as the best possible one between the worst partial grades expected (R, M or F). It can be concluded that all elements of (R, M and F) that make the E have equal influence on E, so that maxmin composition will be used, which in parallel way treats the partial ones onto the h time of planned shut down due to preventive maintenance. 1995) and OR R M F If we tions that is (according to Fig. 2): with 39 (2012) 89408946 Further, for each outcome its values are calculated (X c ). The outcome which would suit the combination c, it would be calcu- lated following the equations: X c P R;M;E j hi c 3 3 Finally, all of these outcomes are treated with maxmin composi- tion, as follows: (i) For each outcome search for the MINimum value of l R,M,F in vector E c (2). The minimum which would suit the combina- tion o, it would be calculated following the equations: MIN 0 minfl j1;.;5 R ;l j1;.;5 M .;l j1;.;5 F g;for all o 1toO 4 (ii) Outcomes are grouped according to their values X c (3), namely the size of j. (iii) Find the MAXimum between previously identified mini- mums (i) for each group (ii) of outcomes. The maximum which would suit value of j, would be calculated following the equations: MAX j maxfMIN o g; for every j 5 E assessment of technical system is obtained in the form: l E This expression (Fig. 2 tion of to fuzzy cedure (d) between the E which d i E j ;H take into account only values if l j1;.;5 R;M;F 0, we get combina- are named outcomes (o =1toO, where O # C). in the process of synthesis, are also used. Precisely, if we look at three partial indicators, namely their membership function (1), it is possible to make C = j 3 =5 3 combina- tions of their membership functions. Each of these combinations represents one possible synthesis effectiveness assessment (E). E l j1;.;5 ;l j1;.;5 ; .;l j1;2;.5 hi ; for all c 1toC 2 maxmin compositions which by using operators AND provide an advantage to certain elements over the others synthetic indicator. In literature (Ivezic et al., 2008; Wang et al., Fig. 2. Effectiveness fuzzy sets. 8942 R. Miodragovic et al./Expert Systems MAX j1 ; .;MAX j5 l 1 E ; .;l 5 E 6 (6) is necessary to map back to the E fuzzy sets ). Best-fit (Wang et al., 1995), method is used for transforma- E description (6) to form that defines grade of membership sets: poor, adequate, average, good and excellent. This pro- is recognized as identification. Best-fit method uses distance E obtained by maxmin composition (6) and each of expressions (according to Fig. 2), to represent the degree to E is confirmed to each of fuzzy sets of effectiveness (Fig. 2). i X 5 j1 l j E C0l j H j 2 v u u t ; j 1; .;5;H i fexcellent;goodaverage;adequate;poorg7 E i fb i1 ;poor;b i2 ;adequate;b i3 ;good; b i4 ;average;b i5 ;excellentg 10 3. An illustrative example As an illustrative example of evaluation of agriculture machin- ery effectiveness, the comparative analysis of three tractors A 1 B 2 , and C 2 is given in this article. In tractor A a 7.146 l engine LO4V TCD 2013 is installed. Thanks to the reserves of torque from 35%, the tractor is able to meet all the requirements expected in the worst performing farming oper- ations in agriculture. Total tractor mass is 16,000 kg. According to OECD (CODE II) report maximum power measured at the PTO shaft is 243 kW at 2200 rpm with specific fuel consumption of 198 g/kW h (ECE-R24). Maximum engine torque is 1482 Nm at en- gine regime of 1450 rpm. Transmission gear is vario continious transmision. Linkage mechanism is a Category II/III with lifting force of 11,800 daN. In tractors B 2 and C 2 8.134 l engine 6081HRW37 JD is installed, with reserve torque of 40%, and this tractor was able to meet all the requirements expected in the worst performance of the farming operations in agriculture. Total tractor weight is 14,000 kg. Accord- ing to OECD (CODE II) report maximum power measured at the PTO shaft is 217 kW at 2002 rpm with specific fuel consumption of 193 g/kW h (ECE-R24). Maximum torque is 1320 Nm at engine revs of 1400 rpm. Transmission is AutoPower. Linkage mechanism is a Category II/III with lifting force of 10,790 daN. Both models have electronically controlled tractor engine and fuel supply system that meets the regulations on emissions. From the submitted technical characteristics of the tractor A, B and C it is seen that all three tractors are fully functional for l exc. = (0,0,0,0.25,1); l good = (0,0,0.25,1,0.25); l aver. = (0,0.25,1,0.25,0); l adeq. = (0.25,1,0.25,0,0); l poor = (1,0.25,0,0,0). The closer l E (6) is to the ith linguistic variable, the smaller d i is. Distance d i is equal to zero, if l E (6) is just the same as the ith expression in terms of the membership functions. In such a case, E should not be evaluated to other expressions at all, due to the exclusiveness of these expressions. Suppose d imin (i =1,.,5) is the smallest among the obtained distances for E j and leta 1 ,.,a 5 represent the reciprocals of the rel- ative distances (which is calculated as the ratio between corres- ponding distance d i (7) and the mentioned values d imin ). Then, a i can be defined as follows: a i 1 d i =d imin ; i 1; .;5 8 If d i = 0 it follows that a i = 1 and the others are equal to zero. Then, a i can be normalized by: b i a j P 5 m1 a im ; i 1; .;5 X 5 i1 b i 1 9 Each b i represents the extent to which E belongs to the ith defined E expressions. It can be noted that if E i completely belongs to the ith expression then b i is equal to 1 and the others are equal to 0. Thus b j could be viewed as a degree of confidence that E i belongs to the ith E expressions. Final expression for E performance at the level of tech- nical system, have been obtained in the form (10) where Applications 1 Tractor Fendt Vario 936. 2 Tractor John Deere 8520. performing 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 that the tractor B entered into operation in May 2007, a tractor C in June 2007. A tractor on the experimental farm, which is the technical documentation for the base model, comes into operation in July 2009. The main task of maintaining agricultural techniques is to provide functionality and reliability of machines. Maintenance of all 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 F are given in Table 1. First, the effectiveness of tractor A is calculated. It can be seen that 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=poor11 In the same way the assessments for M and F are obtained: M 0:4=exc; 0:4=good; 0:2=aver; 0=adeq; 0=poor F 0:5=exc; 0:5=good; 0=aver; 0=adeq; 0=poor In 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 linguistic variable excellent joined weight 0.6. Thereby, fuzzy set excellent is defined as: R exc = (1/0, 2/0, 3/0, 4/0.25, 5/1.0) (according to Fig. 1). In this way the specific values of fuzzy set excellent R exc0.6 = (1/(0 C2 0.6), 2/(0 C2 0.6), 3/(0 C2 0.6), 4/(0.25 C2 0.6), 5/(1.0 C2 0.6) are obtained. The remaining four linguistic variables are treated in the same way. In the end for each j =1,.,5 specific membership functions (last row, Table 2) are added into the final fuzzy form (1) of tractor A reliability: l RA 0;0:025;0:175;0:475;0:675 In the same way, based on the questionnaire (Table 1) values for maintainability and functionality are obtained: l MA 0;0:05;0:3;0:55;0:5; l FA 0;0;0:125;0:625;0:62512 These fuzzificated assessments (11) and (12) are necessary to syn- thesize into assessment of effectiveness, using maxmin logics. In this case it is possible to make C =5 3 = 125 combinations, out of which the 48 outcomes. First outcome would be for combination 2-2-3: E 2-2-3 = 0.025,0.05,0.125, where is X 2-2-3 = (2 + 2 + 3)/3 = 2 (rounded as integer). Smallest value among the membership func- tions of this outcome is 0.025. Other outcomes and corresponding values of X c are shown in Table 3. All these outcomes can be grouped around sizes X = 2, 3, 4 and 5. For example, for outcome X = 5 it can be written: E 4C05C05 0:475;0:5;0:625C138;E 5C04C05 0:675;0:55;0:625C138;E 5C05C04 0:675;0:5;0:625C138;E 5C05C05 0:675;0:5;0:625C138 Further, for each of them, minimum between membership function is sought: Table 1 Results of questionnaire. Average x x xx x xx x R. Miodragovic et al./Expert Systems with Applications 39 (2012) 89408946 8943 Analyst Linguistic variables Tractor A Tractor B Excellent Good Average Adequate Poor Excellent Good 1R x x Mx x Fxxx 2R x Mx x Fx 3R x x Mx Fx 4R x x Mx Fx x 5R x x Mx Fxxx 6R x x Mx Fx x 7R x Mx Fx 8R x x Mx x Fx x 9R x x Mx x Fx x 10 R x x Mx x Fx x Tractor C Adequate Poor Excellent Good Average Adequate Poor x x x x x x x x x x x xx x x x x x x x x x with Table 2 Calculation of specific values of fuzzy sets. 12345 0.6/exc. 0 C2 0.6 0 C2 0.6 0 C2 0.6 0.25 C2 0.6 1.0 C2 0.6 0.3/good 0 C2 0.3 0 C2 0.3 0.25 C2 0.3 1.0 C2 0.3 0.25 C2 0.3 8944 R. Miodragovic et al./Expert Systems MINE 4C05C05 minf0:475;0:5;0:625g0:475;MINE 5C04C05 0:55;MINE 5C05C04 0:5;MINE 5C05C05 0:5 Between these minimums, in the end it seeks maximum: MAXX d5 maxf0:475;0:55;0:5;0:5g0:55 Also for other values: X: MAX X =2 = 0.025; MAX X =3 = 0.175; MAX X =4 = 0.55 (Table 1.) 0.1/aver. 0 C2 0.1 0.25 C2 0.1 1.0 C2 0.1 0.25 C2 0.1 0 C2 0.1 0/adeq. 0.25 C2 0 1.0 C2 0 0.25 C2 00C2 00C2 0 0/poor 1.0 C2 0 0.25 C2 00C2 C2 C2 0 P R 0 0.025 0.175 0.475 0.675 Table 3 Structure of MAXMIN composition. Comb. X l MIN 2345 2-2-3 2 0.025,0.05,0.125 0.025 2-2-4 3 0.025,0.05,0.625 0.025 2-2-5 3 0.025,0.05,0.625 0.025 2-3-3 3 0.025,0.3,0.125 0.025 2-3-4 3 0.025,0.3,0.625 0.025 2-3-5 3 0.025,0.3,0.625 0.025 2-4-3 3 0.025,0.55,0.125 0.025 2-4-4 3 0.025,0.55,0.625 0.025 2-4-5 4 0.025,0.55,0.625 0.025 2-5-3 3 0.025,0.5,0.125 0.025 2-5-4 4 0.025,0.5,0.625 0.025 2-5-5 4 0.025,0.5,0.625 0.025 3-2-3 3 0.175,0.05,0.125 0.05 3-2-4 3 0.175,0.05,0.625 0.05 3-2-5 3 0.175,0.05,0.625 0.05 3-3-3 3 0.175,0.3,0.125 0.125 3-3-4 3 0.175,0.3,0.625 0.175 3-3-5 4 0.175,0.3,0.625 0 0.175 3-4-3 3 0.175,0.55,0.125 0.125 3-4-4 4 0.175,0.55,0.625 0.175 3-4-5 4 0.175,0.55,0.625 0.175 3-5-3 4 0.175,0.5,0.125 0.125 3-5-4 4 0.175,0.5,0.625 0.175 3-5-5 4 0.175,0.5,0.625 0.175 4-2-3 3 0.475,0.05,0.125 0.05 4-2-4 3 0.475,0.05,0.625 0.05 4-2-5 4 0.475,0.05,0.625 0.05 4-3-3 3 0.475,0.3,0.125 0.125 4-3-4 4 0.475,0.3,0.625 0.3 4-3-5 4 0.475,0.3,0.625 0.3 4-4-3 4 0.475,0.55,0.125 0.125 4-4-4 4 0.475,0.55,0.625 0.475 4-4-5 4 0.475,0.55,0.625 0.475 4-5-3 4 0.475,0.5,0.125 0.125 4-5-4 4 0.475,0.5,0.625 0.475 4-5-5 5 0.475,0.5,0.625 0.475 5-2-3 3 0.675,0.05,0.125 0.05 5-2-4 4 0.675,0.05,0.625 0.05 5-2-5 4 0.675,0.05,0.625 0.05 5-3-3 4 0.675,0.3,0.125 0.125 5-3-4 4 0.675,0.3,0.625 0.3 5-3-5 4 0.675,0.3,0.625 0.3 5-4-3 4 0.675,0.55,0.125 0.125 5-4-4 4 0.675,0.55,0.625 0.55 5-4-5 5 0.675,0.55,0.625 0.55 5-5-3 4 0.675,0.5,0.125 0.125 5-5-4 5 0.675,0.5,0.625 0.5 5-5-5 5 0.675,0.5,0.625 0.5 MAX 0.025 0.175 0.55 0.55 Finally, we get expression for membership function of effective- ness of tractor A: l EA 0;0:025;0:175;0:55;0:55 Best-fit method (79) and proposed E fuzzy set (Fig. 1) give the final effectiveness assessment for the tractor A: d 1 E;exc X 5 j1 l j E C0l j exc 2 v u u t 0C00 2 0:025C00 2 0:175C00 2 0:55C00:25 2 0:55C01 2 q 0:56899 where is : l E 0;0:025;0:175;0:55;0:55 l exc 0;0;0;0:25;1 For other fuzzy sets: d 2 (E, good) = 0.54658, d 3 (E, aver) = 1.06007, d 4 (E, adeq) = 1.27426, d 5 (E, poor) = 1.29856. for d min d 2 : a 1 1 d 1 =d 2 1 0:56899=0:54658 0:96061; a 2 1:00000;a 3 0:51561;a 4 0:42894;a 5 0:42091: b 1 a 1 P 5 i1 a i 0:96901 0:96901 1 0:51561 0:42894 0:42091 0:28881; b 2 0:30065;b 3 0:15502;b 4 0:12896;b 5 0:12655: Finally, we get the assessment of effectiveness of tractor A, in form (10): E A =(b 1 , excellent), (b 2 , good), (b 3 , average), (b 4 , ade- quate), (b 5 , poor) = (0.28881, excellent), (0.30065, good), (0.15502, average), (0.12896, adequate), (0.12655, poor) In the same way, we get the assessments for other two tractors B and C: E B = (0.23793, excellent), (0.27538, good), (0.20635, aver- age), (0.14693, adequate), (0.13342, poor) E C = (0.17507, excellent), (0.25092, good), (0.25468, aver- age), (0.17633, adequate), (0.14300, poor). Tractor A is in great extent of 0.30065 (in relation to 30 %) as- sessed as good, tractor B in great extent of 0.27538 (27.5%) as- Applications 39 (2012) 89408946 sessed as good, while tractor C is in great extent of 0.25468 (25.5%) assessed as average. It can be concluded that C is the worst, while tractor A is only somewhat better than B, especially if we see with that A is assessed as excellent in the extent of 28.8% while B in the extent of 23.8%. Effectiveness of analyzed tractors can be presented as in Fig. 3., where it can be more clearly seen that tractor A has the biggest effectiveness. If this assessment (E A , E B , E C ) is defuzzificated by center of mass point calculation Z (Bowles if calculated on 10,000 moto-hours, Fig. 3. Relationship of effectiveness of observed tractors. R. Miodragovic et al./Expert Systems it would spend in work 9244 moto-hours. As of the tractor B, out of 10,004 available moto-hours, it spent 9069 moto-hours in work, and tractor C out of 9981 available moto-hours spent 9045 in work. The experiment showed that the more reliable and efficient tractors are the less frequent are delays. In part, this initial advan- tage wiped out worse logistics of delivery of spare parts when it comes to tractor A. in 1100 moto-hours work of the tractor, due to poor logistics in maintaining hoped to eight working days, and it greatly influenced the decline in benefits of maintainability of a given tractor and thus the decline in total exploitation of the same efficiency (Internal technical documentation PKB). 4. Conclusion This paper presents a model for effectiveness assessment of technical systems, precisely agricultural machinery, based on fuzzy sets theory. Effectiveness performance has been adopted as overall indicator of systems quality of service, i.e. as entire measure of technical system availability. Reliability, maintainability and func- tionality performances have been recognized as effectiveness parameters or indicators. Linguistic form can be appointed as the References Bowles, J. B., & Pelaez, C. E. (1995). Fuzzy logic prioritization of failures in a system failure mode, effects and criticality analysis. Reliability Engineering and System Safety, 50(2), 203213. Cai, K. Y. (1996).