發(fā)動機(jī)氣門生產(chǎn)工序工業(yè)機(jī)器人腰部機(jī)構(gòu)及傳動設(shè)計(jì)
購買設(shè)計(jì)請充值后下載,資源目錄下的文件所見即所得,都可以點(diǎn)開預(yù)覽,資料完整,充值下載可得到資源目錄里的所有文件。【注】:dwg后綴為CAD圖紙,doc,docx為WORD文檔,原稿無水印,可編輯。具體請見文件預(yù)覽,有不明白之處,可咨詢QQ:12401814
分 類 號 密 級 寧學(xué)院畢業(yè)設(shè)計(jì)(論文)發(fā)動機(jī)氣門生產(chǎn)工序工業(yè)機(jī)器人腰部機(jī)構(gòu)及傳動設(shè)計(jì)所在學(xué)院專 業(yè)班 級姓 名臧云鋒學(xué) 號指導(dǎo)老師朱火美 年 月 日誠 信 承 諾我謹(jǐn)在此承諾:本人所寫的畢業(yè)論文發(fā)動機(jī)氣門生產(chǎn)工序工業(yè)機(jī)器人腰部機(jī)構(gòu)及傳動設(shè)計(jì)均系本人獨(dú)立完成,沒有抄襲行為,凡涉及其他作者的觀點(diǎn)和材料,均作了注釋,若有不實(shí),后果由本人承擔(dān)。 承諾人(簽名): 年 月 日摘 要機(jī)器人既有人對環(huán)境的快速反應(yīng)和分析判斷能力,又有機(jī)器可長時(shí)間持續(xù)工作、精確度高、抗惡劣環(huán)境的能力,從某種意義上說它是機(jī)器的進(jìn)化過程產(chǎn)物,它是工業(yè)以及非產(chǎn)業(yè)界的重要生產(chǎn)和服務(wù)性設(shè)備,也是先進(jìn)制造技術(shù)領(lǐng)域不可缺少的自動化設(shè)備。如今,機(jī)器人工業(yè)已成為世界各國備受關(guān)注的產(chǎn)業(yè)。關(guān)鍵詞:機(jī)器人;工業(yè);傳動;強(qiáng)度31AbstractRobot people on the environment both rapid reaction and analytical skills, but also the machine can continue to work long hours,High accuracy, ability to resist bad environmental,In a sense it is a product of the evolution of the machine,It is the industrial and non-industrial sector, an important production and service equipment,Advanced manufacturing technology is indispensable automation equipment。Today, the robot industry has become the industry closely watched around the world.Key Words: Robot; industry; transmission; strength目 錄摘 要3Abstract4目 錄5第1章緒論71.1 機(jī)器人概念71.2 課題研究的背景和意義71.3 國內(nèi)機(jī)器人的研究81.4 本課題研究內(nèi)容9第2章機(jī)器人總體設(shè)計(jì)102.1 確定基本技術(shù)參數(shù)102.1.1 機(jī)械結(jié)構(gòu)類型的選擇102.1.2 額定負(fù)載112.1.3 工作范圍112.1.4 操作機(jī)的驅(qū)動系統(tǒng)設(shè)計(jì)122.1.5 控制系統(tǒng)選擇122.1.6 確定機(jī)器人手臂的配置形式132.2 機(jī)器人本體結(jié)構(gòu)設(shè)計(jì)14第3章機(jī)器人腰部結(jié)構(gòu)設(shè)計(jì)163.1 電動機(jī)的選擇163.2 計(jì)算傳動裝置的總傳動比和分配各級傳動比183.3 軸的設(shè)計(jì)計(jì)算183.3.1 計(jì)算各軸轉(zhuǎn)速、轉(zhuǎn)矩和輸入功率183.3.2 確定三根軸的具體尺寸193.4 確定齒輪的參數(shù)233.4.1選擇材料233.4.2 壓力角的選擇233.4.3 齒數(shù)和模數(shù)的選擇233.4.4齒寬系數(shù)243.4.5 確定齒輪傳動的精度243.4.6 齒輪的校核253.5 殼體設(shè)計(jì)283.6小結(jié)28總 結(jié)29參考文獻(xiàn)30寧波大紅鷹學(xué)院本科生畢業(yè)設(shè)計(jì)第1章 緒論1.1 機(jī)器人概念機(jī)器人(Robot)是自動執(zhí)行工作的機(jī)器裝置。它既可以接受人類指揮,又可以運(yùn)行預(yù)先編排的程序,也可以根據(jù)以人工智能技術(shù)制定的原則綱領(lǐng)行動。它的任務(wù)是協(xié)助或取代人類工作的工作,例如生產(chǎn)業(yè)、建筑業(yè),或是危險(xiǎn)的工作。它是高級整合控制論、機(jī)械電子、計(jì)算機(jī)、材料和仿生學(xué)的產(chǎn)物。在工業(yè)、醫(yī)學(xué)、農(nóng)業(yè)、建筑業(yè)甚至軍事等領(lǐng)域中均有重要用途。 本田公司ASIMO機(jī)器人現(xiàn)在,國際上對機(jī)器人的概念已經(jīng)逐漸趨近一致。一般來說,人們都可以接受這種說法,即機(jī)器人是靠自身動力和控制能力來實(shí)現(xiàn)各種功能的一種機(jī)器。聯(lián)合國標(biāo)準(zhǔn)化組織采納了美國機(jī)器人協(xié)會給機(jī)器人下的定義:“一種可編程和多功能的操作機(jī);或是為了執(zhí)行不同的任務(wù)而具有可用電腦改變和可編程動作的專門系統(tǒng)?!彼転槿祟悗碓S多方便之處。機(jī)器人是近30年發(fā)展起來的一種典型的、機(jī)電一體化的、獨(dú)立的自動化生產(chǎn)工具。在制造工業(yè)中,應(yīng)用工業(yè)機(jī)器人技術(shù)是提高生產(chǎn)過程自動化,改善勞動條件,提高產(chǎn)品質(zhì)量和生產(chǎn)效率的有效手段之一,也是新技術(shù)革命的一個(gè)重要內(nèi)容。1.2 課題研究的背景和意義機(jī)器人的出現(xiàn)和應(yīng)用是人類生產(chǎn)和社會進(jìn)步的需要,是科學(xué)技術(shù)發(fā)展和生產(chǎn)工具進(jìn)化的必然。機(jī)器人一詞最早出現(xiàn)于1920年捷克作家Karel Capek的劇本羅薩姆的萬能機(jī)器人中,在該劇中,機(jī)器人“Robota”這個(gè)詞的本意是指苦力,是劇作家筆下的一個(gè)具有人的外表、特征和功能的機(jī)器,是一種人造的勞動力。隨著現(xiàn)代科技的發(fā)展,機(jī)器人技術(shù)已經(jīng)廣泛應(yīng)用于人類生活領(lǐng)域,研制具有人類外觀特征、可模擬人類行走和其他動作的機(jī)器人一直是人類的夢想之一。機(jī)器人是一門綜合性很強(qiáng)的科學(xué),有著極其廣泛的研究和應(yīng)用領(lǐng)域。機(jī)器人技術(shù)是綜合了計(jì)算機(jī)技術(shù)、信息融合技術(shù)、機(jī)構(gòu)學(xué)、傳感技術(shù)、仿生科學(xué)以及人工智能等多學(xué)科而形成的高新技術(shù),它不僅涉及到線性、非線性、基于多種傳感器信息控制以及實(shí)時(shí)控制技術(shù),而且還包括復(fù)雜機(jī)電系統(tǒng)的建模、數(shù)字仿真技術(shù)及混合系統(tǒng)的控制研究等方面的技術(shù)。機(jī)器人是機(jī)器人技術(shù)中的一個(gè)重要研究課題,而雙足機(jī)器人是機(jī)器人研究的前奏。步行技術(shù)是人與大多數(shù)動物所具有的移動方式,是一種高度自動化的運(yùn)動,雙足步行系統(tǒng)具有非常復(fù)雜的動力學(xué)特性,對于環(huán)境具有很強(qiáng)的適應(yīng)性,它相對輪式、履帶式機(jī)器人具有無可比擬的優(yōu)越性,它可以進(jìn)入狹窄的作業(yè)空間,也可跨越障礙、上下臺階、斜坡及在不平整地面上工作,可以護(hù)理老人、康復(fù)醫(yī)學(xué)以及在一般家庭的家政服務(wù)都可以應(yīng)用。它適應(yīng)環(huán)境的能力更強(qiáng),因此具有更加廣泛的應(yīng)用前景。在機(jī)器人的研制中,機(jī)器人仿真是機(jī)器人研究的一項(xiàng)重要的內(nèi)容,它涉及機(jī)器人機(jī)構(gòu)學(xué)、機(jī)器人運(yùn)動學(xué)、機(jī)器人零件建模、仿真機(jī)器人三維實(shí)現(xiàn)和機(jī)器人的運(yùn)動控制,是一項(xiàng)綜合性有創(chuàng)新意義和實(shí)用價(jià)值的研究課題。仿真利用計(jì)算機(jī)可視化和面向?qū)ο蟮氖侄?,模擬機(jī)器人的動態(tài)特性,幫助研究人員了解機(jī)器人工作空間的形態(tài)及極限,提示機(jī)構(gòu)的合理運(yùn)動方案及有效的控制算法,從而解決在機(jī)器人設(shè)計(jì)、制造以及運(yùn)行過程中的問題,避免了直接操作實(shí)體可能會造成的事故或者不必要的損失。仿真也為機(jī)器人本體結(jié)構(gòu)方案設(shè)計(jì)提供參考依據(jù),并在這臺機(jī)器上模擬能都實(shí)現(xiàn)的功能,使用戶直接看到設(shè)計(jì)效果,及時(shí)找出缺點(diǎn)和不足進(jìn)行改進(jìn),避免了大量的物力、人力的浪費(fèi)1,2。1.3 國內(nèi)機(jī)器人的研究我國已在“七五”計(jì)劃中把機(jī)器人列人國家重點(diǎn)科研規(guī)劃內(nèi)容,撥巨款在沈陽建立了全國第一個(gè)機(jī)器人研究示范工程,全面展開了機(jī)器人基礎(chǔ)理論與基礎(chǔ)元器件研究。十幾年來,相繼研制出示教再現(xiàn)型的搬運(yùn)、點(diǎn)焊、弧焊、噴漆、裝配等門類齊全的工業(yè)機(jī)器人及水下作業(yè)、軍用和特種機(jī)器人。目前,示教再現(xiàn)型機(jī)器人技術(shù)已基本成熟,并在工廠中推廣應(yīng)用。我國自行生產(chǎn)的機(jī)器人噴漆流水線在長春第一汽車廠及東風(fēng)汽車廠投入運(yùn)行。1986年3月開始的國家863高科技發(fā)展規(guī)劃已列入研究、開發(fā)智能機(jī)器人的內(nèi)容。就目前來看,我們應(yīng)從生產(chǎn)和應(yīng)用的角度出發(fā),結(jié)合我國國情,加快生產(chǎn)結(jié)構(gòu)簡單、成本低廉的實(shí)用型機(jī)器人和某些特種機(jī)器人。國內(nèi)機(jī)器人的研究也在863計(jì)劃和自然科學(xué)基金的支持下持續(xù)開展了多年,如國防科技大學(xué)、哈爾濱工業(yè)大學(xué)、北京理工大學(xué)、清華大學(xué)、上海交通大學(xué)、中國科學(xué)技術(shù)大學(xué)等,都先后開始研制機(jī)器人樣機(jī)4。1.4 本課題研究內(nèi)容本課題的主要任務(wù)是對機(jī)器人的腰部及傳動進(jìn)行設(shè)計(jì),并完成總裝配圖和零件圖的繪制。要求對機(jī)器人模型進(jìn)行靜力學(xué)分析,估算各關(guān)節(jié)所需轉(zhuǎn)矩和功率,完成電機(jī)和減速器的選型。其次從電機(jī)和減速器的連接和固定出發(fā),設(shè)計(jì)關(guān)節(jié)結(jié)構(gòu),并對機(jī)構(gòu)中的重要連接件進(jìn)行強(qiáng)度校核。主要任務(wù):(1)機(jī)器人腰部機(jī)構(gòu)設(shè)計(jì)、三維造型(2)機(jī)器人腰部受力計(jì)算與校核(3)機(jī)器人腰關(guān)節(jié)傳動設(shè)計(jì)(4)重要零件圖及裝配圖繪制(5)伺服電機(jī)選型(6)撰寫1萬字以上設(shè)計(jì)說明書一份原始數(shù)據(jù):氣門電鐓成型工序電鐓機(jī)、摩擦壓力機(jī)與機(jī)機(jī)器人布置如下圖所示。以機(jī)機(jī)器人為中心,半徑為875mm的圓周上,布置三臺電鐓機(jī)和一臺摩擦壓力機(jī)。電鐓機(jī)工作平面高1500mm,摩擦壓力機(jī)工作平面高900mm,預(yù)留機(jī)器人基座高度500mm。電鐓機(jī)每29秒完成一個(gè)毛坯的電鐓工作,摩擦壓力機(jī)6秒可完成壓力成型工序。機(jī)器人的工作任務(wù)是將電鐓后的工件及時(shí)送入摩擦壓力機(jī)的工作區(qū)域,即每9.6秒需要完成從零件抓取到最后零件釋放的一系列動作。相關(guān)設(shè)備現(xiàn)場布置示意圖及機(jī)器人機(jī)構(gòu)簡圖根據(jù)以上工作要求,綜合考慮機(jī)器人的功能實(shí)現(xiàn)和通用性,確定采用六自由度結(jié)構(gòu)。整體方案確定各連桿長度(以轉(zhuǎn)動副的中心為端點(diǎn))數(shù)據(jù)如下,連桿1(即大臂)長650mm,連桿2(即小臂)長570mm,連桿3(即手爪)長280mm。初定各關(guān)節(jié)額定轉(zhuǎn)速為20r/min,手爪末端額定負(fù)載為5kg。機(jī)器人結(jié)構(gòu)簡圖如上圖所示,關(guān)節(jié)1為腰部旋轉(zhuǎn)關(guān)節(jié),關(guān)節(jié)2為大臂俯仰關(guān)節(jié),關(guān)節(jié)3為小臂俯仰關(guān)節(jié),關(guān)節(jié)4為小臂旋轉(zhuǎn)關(guān)節(jié),關(guān)節(jié)5為手腕俯仰關(guān)節(jié),關(guān)節(jié)6為手腕旋轉(zhuǎn)關(guān)節(jié),本課題的任務(wù)就是對機(jī)器人腰部機(jī)構(gòu)及傳動進(jìn)行設(shè)計(jì)。第2章 機(jī)器人總體設(shè)計(jì)2.1 確定基本技術(shù)參數(shù)2.1.1 機(jī)械結(jié)構(gòu)類型的選擇為實(shí)現(xiàn)總體機(jī)構(gòu)在空間的位置提供的6個(gè)自由度,可以有不同的運(yùn)動組合,根據(jù)本課題可以將其設(shè)計(jì)成以下五種方案:a.圓柱坐標(biāo)型 這種運(yùn)動形式是通過一個(gè)轉(zhuǎn)動,兩個(gè)移動,共三個(gè)自由度組成的運(yùn)動系統(tǒng),工作空間圖形為圓柱型。它與直角坐標(biāo)型比較,在相同的工作空間條件下,機(jī)體所占體積小,而運(yùn)動范圍大。b.直角坐標(biāo)型 直角坐標(biāo)型工業(yè)機(jī)器人,其運(yùn)動部分由三個(gè)相互垂直的直線移動組成,其工作空間圖形為長方體。它在各個(gè)軸向的移動距離,可在各坐標(biāo)軸上直接讀出,直觀性強(qiáng),易于位置和姿態(tài)的編程計(jì)算,定位精度高、結(jié)構(gòu)簡單,但機(jī)體所占空間體積大、靈活性較差。c.球坐標(biāo)型 又稱極坐標(biāo)型,它由兩個(gè)轉(zhuǎn)動和一個(gè)直線移動所組成,即一個(gè)回轉(zhuǎn),一個(gè)俯仰和一個(gè)伸縮運(yùn)動組成,其工作空間圖形為一個(gè)球形,它可以作上下俯仰運(yùn)動并能夠抓取地面上或較低位置的工件,具有結(jié)構(gòu)緊湊、工作空間范圍大的特點(diǎn),但結(jié)構(gòu)復(fù)雜。d. 又稱回轉(zhuǎn)坐標(biāo)型,這種機(jī)器人的手臂與人體上肢類似,其前三個(gè)關(guān)節(jié)都是回轉(zhuǎn)關(guān)節(jié),這種機(jī)器人一般由立柱和大小臂組成,立柱與大臂間形成肩關(guān)節(jié),大臂和小臂間形成肘關(guān)節(jié),可使大臂作回轉(zhuǎn)運(yùn)動和使大臂作俯仰擺動,小臂作俯仰擺動。其特點(diǎn)使工作空間范圍大,動作靈活,通用性強(qiáng)、能抓取靠進(jìn)機(jī)座的物體。 e.平面 采用兩個(gè)回轉(zhuǎn)關(guān)節(jié)和一個(gè)移動關(guān)節(jié);兩個(gè)回轉(zhuǎn)關(guān)節(jié)控制前后、左右運(yùn)動,而移動關(guān)節(jié)則實(shí)現(xiàn)上下運(yùn)動,其工作空間的軌跡圖形,它的縱截面為矩形的同轉(zhuǎn)體,縱截面高為移動關(guān)節(jié)的行程長,兩回轉(zhuǎn)關(guān)節(jié)轉(zhuǎn)角的大小決定回轉(zhuǎn)體橫截面的大小、形狀。在水平方向有柔順性,在垂直方向有較大的剛性。它結(jié)構(gòu)簡單,動作靈活,多用于裝配作業(yè)中,特別適合小規(guī)格零件的插接裝配。對以上五種方案進(jìn)行比較:方案一不能夠完全實(shí)現(xiàn)本課題所要求的動作;方案二體積大,靈活性差;方案三結(jié)構(gòu)復(fù)雜;方案五無法實(shí)現(xiàn)本課題的動作。結(jié)合本課題綜合考慮決定采用方案四:機(jī)器人。此方案所占空間少,工作空間范圍大,動作靈活,工藝操作精度高。2.1.2 額定負(fù)載目前,國內(nèi)外使用的工業(yè)機(jī)器人中,其負(fù)載能力的范圍很大,最小的額定負(fù)載在5N以下,最大可達(dá)9000N。負(fù)載大小的確定主要是考慮沿機(jī)器人各運(yùn)動方向作用于機(jī)械接口處的力和扭矩。其中應(yīng)包括機(jī)器人末端執(zhí)行器的重量、抓取工件或作業(yè)對象的重量和在規(guī)定速度和加速度條件下,產(chǎn)生的慣性力矩。本課題的任務(wù)要求是保證手腕部能承受的最大載荷是5kg。2.1.3 工作范圍工業(yè)機(jī)器人的工作范圍是根據(jù)工業(yè)機(jī)器人作業(yè)過程中的操作范圍和運(yùn)動的軌跡來確定的,用工作空間來表示的。工作空間的形狀和尺寸則影響機(jī)器人的機(jī)械結(jié)構(gòu)坐標(biāo)型式、自由度數(shù)和操作機(jī)各手臂關(guān)節(jié)軸線間的長度和各關(guān)節(jié)軸轉(zhuǎn)角的大小及變動范圍的選擇。2.1.4 操作機(jī)的驅(qū)動系統(tǒng)設(shè)計(jì)機(jī)器人本體驅(qū)動系統(tǒng)包括驅(qū)動器和傳動機(jī)構(gòu),它們常和執(zhí)行機(jī)構(gòu)聯(lián)成一體,驅(qū)動臂桿和載荷完成指定的運(yùn)動。通常的機(jī)器人驅(qū)動方式有以下四種: a.步進(jìn)電機(jī):可直接實(shí)現(xiàn)數(shù)字控制,控制結(jié)構(gòu)簡單,控制性能好,而且成本低廉;通常不需要反饋就能對位置和速度進(jìn)行控制。但是由于采用開環(huán)控制,沒有誤差校正能力,運(yùn)動精度較差,負(fù)載和沖擊震動過大時(shí)會造成“失步”現(xiàn)象。 b.直流伺服電機(jī):直流伺服電機(jī)具有良好的調(diào)速特性,較大的啟動力矩,相對功率大及快速響應(yīng)等特點(diǎn),并且控制技術(shù)成熟。其安裝維修方便,成本低。c.交流伺服電機(jī):交流伺服電機(jī)結(jié)構(gòu)簡單,運(yùn)行可靠,使用維修方便,與步進(jìn)電機(jī)相比價(jià)格要貴一些。隨著可關(guān)斷晶閘管GTO,大功率晶閘管GTR和場效應(yīng)管MOSFET等電力電子器件、脈沖調(diào)寬技術(shù)(PWM)和計(jì)算機(jī)控制技術(shù)的發(fā)展,使交流伺服電機(jī)在調(diào)速性能方面可以與直流電機(jī)媲美。采用16位CPU+32位DSP三環(huán)(位置、速度、電流)全數(shù)字控制,增量式碼盤的反饋可達(dá)到很高的精度。三倍過載輸出扭矩可以實(shí)現(xiàn)很大的啟動功率,提供很高的響應(yīng)速度。d.液壓伺服馬達(dá):液壓伺服馬達(dá)具有較大的功率/體積比,運(yùn)動比較平穩(wěn),定位精度較高,負(fù)載能力也比較大,能夠抓住重負(fù)載而不產(chǎn)生滑動,從體積、重量及要求的驅(qū)動功率這幾項(xiàng)關(guān)鍵技術(shù)考慮,不失為一個(gè)合適的選擇方案。但是,其費(fèi)用較高,其液壓系統(tǒng)經(jīng)常出現(xiàn)漏油現(xiàn)象。為避免本系統(tǒng)也出現(xiàn)同類問題,在可能的前提下,本系統(tǒng)將盡量避免使用該種驅(qū)動方式。常用的驅(qū)動器有電機(jī)和液壓、氣動驅(qū)動裝置等。其中采用電機(jī)驅(qū)動是最常用的驅(qū)動方式。電極驅(qū)動具有精度高,可靠性好,能以較大的變速范圍滿足機(jī)器人應(yīng)用要求等特點(diǎn)。所以在這次設(shè)計(jì)中我選擇了直流電機(jī)作為驅(qū)動器。因?yàn)樗哂畜w積小、轉(zhuǎn)矩大、輸出力矩和電流成比例、伺服性能好、反應(yīng)快速、功率重量比大,穩(wěn)定性好等優(yōu)點(diǎn)。本課題的機(jī)器人將采用直流伺服電動機(jī)。因?yàn)樗哂畜w積小、轉(zhuǎn)矩大、輸出力矩和電流成比例、伺服性能好、反應(yīng)快速、功率重量比大,穩(wěn)定性好等優(yōu)點(diǎn)。2.1.5 控制系統(tǒng)選擇對于焊接機(jī)器人這種精度要求不高的工業(yè)機(jī)器人,大多采用示教再現(xiàn)編程。示教方式作為一種成熟的技術(shù),易被熟悉工作任務(wù)的人員掌握。無論是手把手示教或示教盒示教,都是以在線編程,由示教操作人員操作移動末端執(zhí)行器和手臂到所需的位置。然后記錄(存儲)下這些操作和數(shù)據(jù)。示教過程完成后,即可應(yīng)用,機(jī)器人以再現(xiàn)方式重復(fù)進(jìn)行示教時(shí)存于存儲器的點(diǎn)位、軌跡和各種操作。再現(xiàn)過程的速度可以與示教時(shí)速度不同。利用示教手柄由人工引導(dǎo)末端執(zhí)行器經(jīng)過所要求的軌跡,此時(shí)位置傳感器就檢測出機(jī)器人操作機(jī)上各關(guān)節(jié)處的坐標(biāo)(或轉(zhuǎn)角)值,控制系統(tǒng)的裝置記錄(儲存)下這些數(shù)字化的數(shù)據(jù)信息。再現(xiàn)時(shí),機(jī)器人控制系統(tǒng)重復(fù)再現(xiàn)示教者示教的軌跡和操作技能。手把手示教也能實(shí)現(xiàn)點(diǎn)位控制,所不同的是它只記錄各軌跡程序段的兩端位置。軌跡運(yùn)動速度則按各軌跡程序段對應(yīng)的功能數(shù)據(jù)輸入。2.1.6 確定機(jī)器人手臂的配置形式手臂的配置形式反映了機(jī)器人操作機(jī)的總體布局。根據(jù)任務(wù)要求,要實(shí)現(xiàn)機(jī)器人焊接功能,則機(jī)器人的工作范圍要廣,所以我選擇了立柱式的配置方式。其特點(diǎn)是占地面積小,工作范圍大,機(jī)器人手臂可繞立柱回轉(zhuǎn)。根據(jù)分析,可將機(jī)器人的參數(shù)列在表2-1中:表2-1機(jī)器人的主要參數(shù)項(xiàng)目技術(shù)要求結(jié)構(gòu)型式自由度數(shù)6運(yùn)動范圍308314 292 578 244 534最大速度2ms腕部最大負(fù)荷5續(xù)表2-1項(xiàng)目技術(shù)要求驅(qū)動方式直流電機(jī)重復(fù)定位精度0.05mm2.2 機(jī)器人本體結(jié)構(gòu)設(shè)計(jì)圖2-2 機(jī)器人傳動原理圖圖2-2是整個(gè)機(jī)器人本體機(jī)械傳動系統(tǒng)的簡圖。機(jī)械傳動系統(tǒng)共有30個(gè)齒輪,為了實(shí)現(xiàn)在同一平面改變傳遞方向90,有10個(gè)齒輪為圓錐齒輪,有利于簡化系統(tǒng)運(yùn)動方程式的結(jié)構(gòu)形式。如果采用蝸輪蝸桿結(jié)構(gòu),則必然以空間交叉方式變向,就不利于簡化系統(tǒng)運(yùn)動方程式的結(jié)構(gòu)形式。機(jī)器人主要由立柱與基座組成的回轉(zhuǎn)基座以及大臂、小臂、手腕組成?;且粋€(gè)鋁制的整體鑄件,其上裝有關(guān)節(jié)1的驅(qū)動電機(jī),在基座內(nèi)安置了關(guān)節(jié)1的回轉(zhuǎn)軸及其軸承、軸承座等。大臂和小臂的結(jié)構(gòu)形式相似,都由內(nèi)部鋁制的整體鑄件骨架與外表面很薄的鋁板殼相互膠接而成。內(nèi)部鑄件既作臂的承力骨架,又作內(nèi)部齒輪組的輪殼與軸的支承座。大臂上裝有關(guān)節(jié)2,3的驅(qū)動電機(jī),內(nèi)部裝有對應(yīng)的傳動齒輪組。關(guān)節(jié)2,3都采用了三級齒輪減速,其中第一級采用錐齒輪,以改變傳動方向90。第二、三級均采用圓柱直齒輪進(jìn)行減速。關(guān)節(jié)2傳動的最末一個(gè)大齒輪固定在立柱上;關(guān)節(jié)3傳動的最末一個(gè)大齒輪固定在小臂上。小臂端部連接具有3R手腕,在臂的根部裝有關(guān)節(jié)4,5的驅(qū)動電機(jī),在小臂的中部,靠近手腕處,裝有關(guān)節(jié)6的驅(qū)動電機(jī)。關(guān)節(jié)4,5均采用兩級齒輪傳動,不同的是關(guān)節(jié)4采用兩級圓柱直齒輪,而關(guān)節(jié)5采用第一級圓柱直齒輪,第二級錐齒輪,使傳動軸線改變方向90。關(guān)節(jié)6采用三級齒輪傳動,第一級與第二級為錐齒輪,第三級為圓柱直齒輪,關(guān)節(jié)4,5,6的齒輪組除關(guān)節(jié)4第一級齒輪裝在小臂內(nèi)以外,其余的均裝在手腕內(nèi)部。所設(shè)計(jì)的機(jī)器人本體結(jié)構(gòu)特點(diǎn)如下:a.內(nèi)部鋁鑄件形狀復(fù)雜,既用作內(nèi)部齒輪安裝殼體與軸的支承座,又兼作承力骨架,傳遞集中載荷。這樣不僅節(jié)省材料,減少加工量,又使整體質(zhì)量減輕。手臂外壁與鑄件骨架采用膠接,使連接件減少,工藝簡單,減輕了質(zhì)量。b.軸承外形環(huán)定位簡單。一般在無軸向載荷處,載荷外環(huán)采用端面打沖定位的方法。c. 采用薄壁軸承與滑動銅襯套,以減少結(jié)構(gòu)尺寸,減輕質(zhì)量。d. 有些小尺寸齒輪與軸加工成一體,減少連接件,增加了傳遞剛度。e. 大、小臂,手腕部結(jié)構(gòu)密度大,很少有多余空隙。如電機(jī)與臂的外壁僅有0.5mm間隙,手腕內(nèi)部齒輪傳動安排亦是緊密無間。這樣使總的尺寸減少,質(zhì)量減少。f. 工作范圍大,適應(yīng)性廣。PUMA除了自身立柱所占空間以外,它的工作空間幾乎是他的長臂所能達(dá)到的全球空間。再加之其手腕軸的活動角度大,因此使它工作時(shí)位姿的適應(yīng)性強(qiáng)。譬如用手腕擰螺釘,手腕關(guān)節(jié)4,6配合,一次就能轉(zhuǎn)1112。g. 由于結(jié)構(gòu)上采用了剛性齒輪傳動,調(diào)整齒輪間隙機(jī)構(gòu),彈性萬向聯(lián)軸器,工藝上加工精密,多用整體鑄件,使得重復(fù)定位精度高。h. 機(jī)器人手臂材料的選擇:機(jī)器人手臂的材料應(yīng)根據(jù)手臂的工作狀況來選擇。根據(jù)設(shè)計(jì)要求,機(jī)器人手臂要完成各種運(yùn)動。因此,對材料的一個(gè)要求是作為運(yùn)動的部件,它應(yīng)是輕型材料。而另一方面,手臂在運(yùn)動過程中往往會產(chǎn)生振動,這將大大降低它的運(yùn)動精度。因此,在選擇材料時(shí),需要對質(zhì)量、剛度、阻尼進(jìn)行綜合考慮,以便有效地提高手臂的動態(tài)性能。機(jī)器人手臂材料首先應(yīng)是結(jié)構(gòu)材料。手臂承受載荷時(shí),不應(yīng)有變形和斷裂。從力學(xué)角度看,即要具有一定的強(qiáng)度。手臂材料應(yīng)選擇高強(qiáng)度材料,如鋼、鑄鐵、合金鋼等。機(jī)器人手臂是運(yùn)動的,又要具有很好的受控性,因此,要求手臂比較輕。綜合而言,應(yīng)該優(yōu)先選擇強(qiáng)度大而密度小的材料做手臂。其中,非金屬材料有尼龍6、聚乙烯和碳素纖維等;金屬材料以輕合金為主。在我們的設(shè)計(jì)中為減輕機(jī)器人本體的重量選用鑄鋁材料。第3章 機(jī)器人腰部結(jié)構(gòu)設(shè)計(jì)通過總體分析后,確定了機(jī)器人的結(jié)構(gòu)。所設(shè)計(jì)的腰關(guān)節(jié)部分采用二級齒輪減速傳動。圖3-1 機(jī)器人腰關(guān)節(jié)驅(qū)動器和齒輪傳動機(jī)構(gòu)簡圖3.1 電動機(jī)的選擇設(shè)兩臂及手腕繞各自重心軸的轉(zhuǎn)動慣量分別為JG1、JG2、JG3,根據(jù)平行軸定理可得繞第一關(guān)節(jié)軸的轉(zhuǎn)動慣量為: (3-1) 、分別為10kg、5kg、12kg。、分別為重心到第一關(guān)節(jié)軸的距離,其值分別為300mm、700mm、1500mm,在式(3-1)中、故、可忽略不計(jì)。所以繞第一關(guān)節(jié)軸的轉(zhuǎn)動慣量為: (3-2) = =同理可得小臂及腕部繞第二關(guān)節(jié)軸的轉(zhuǎn)動慣量: = =式中:小臂重心距第二關(guān)節(jié)軸的水平距離 。 腕部重心距第二關(guān)節(jié)軸的水平距離 。設(shè)主軸速度為219/s,則旋轉(zhuǎn)開始時(shí)的轉(zhuǎn)矩可表示如下 (3-3)式中:旋轉(zhuǎn)開始的轉(zhuǎn)矩 角加速度 使機(jī)器人主軸從到/s所需時(shí)間為:則: 若考慮繞機(jī)器人手臂的各部分重心軸的轉(zhuǎn)動慣量及摩擦力矩,則旋轉(zhuǎn)開始時(shí)的啟動轉(zhuǎn)矩可假定為 電動機(jī)的功率可按下式估算 (3-4)式中: 電動機(jī)功率 ; 負(fù)載力矩 ; 負(fù)載轉(zhuǎn)速 ; 傳動裝置的效率,初步估算取0.9; 系數(shù)1.52.5為經(jīng)驗(yàn)數(shù)據(jù),取1.5估算后就可選取電機(jī),使其額定功率滿足下式 (3-5)選擇QZD-08串勵(lì)直流電動機(jī)表3-1 QZD-08串勵(lì)直流電動機(jī)技術(shù)數(shù)據(jù)功率(W)額定電壓(V)額定電流(A)額定轉(zhuǎn)速(r/min)濾磁方式絕緣等級工作制(min)8002446.21750串勵(lì)B603.2 計(jì)算傳動裝置的總傳動比和分配各級傳動比根據(jù)經(jīng)驗(yàn)取主軸的轉(zhuǎn)速4rad/s。傳動裝置總傳動比取48,分二級傳動,第一級是加工在軸上的齒輪與小齒輪嚙合,傳動比=4;第二級傳動比為=12 (3-6)3.3 軸的設(shè)計(jì)計(jì)算3.3.1 計(jì)算各軸轉(zhuǎn)速、轉(zhuǎn)矩和輸入功率a.各軸轉(zhuǎn)速軸 (3-7)軸 (3-8)軸 n= (3-9)b.各軸輸入功率軸 (3-10) 制動器效率軸 (3-11) 齒輪嚙合的效率 角接觸球軸承的效率軸 P=748.90.98=733.9 W (3-12)c.各軸輸入扭矩軸 (3-13)軸 (3-14)軸 T3=9550 (3-15)3.3.2 確定三根軸的具體尺寸兩實(shí)心軸的材料均選用45號鋼,查表知軸的許用扭剪應(yīng)力= 30MPa,由許用應(yīng)力確定的系數(shù)為C=120.A. 第一根軸設(shè)計(jì)及校核a.此軸傳遞扭矩 (3-16)因?yàn)檩S是齒輪軸,所以可以將軸的軸徑加工的大一點(diǎn),以滿足齒輪嚙合時(shí)強(qiáng)度的要求。齒輪的分度圓直徑為50mm,齒輪兩端裝有軸承,加工一段軸肩來定位軸承.齒輪軸上裝型號為 滾動軸承7206AC,內(nèi)徑為30mm。具體尺寸如圖3-2所示。圖3-2 第一級齒輪軸結(jié)構(gòu)圖b.軸在初步完成結(jié)構(gòu)設(shè)計(jì)后,進(jìn)行校核計(jì)算。計(jì)算準(zhǔn)則是滿足軸的強(qiáng)度或剛度要求。進(jìn)行軸的強(qiáng)度校核計(jì)算時(shí),應(yīng)根據(jù)軸的具體受載及應(yīng)力情況,采取相應(yīng)的方法,并恰當(dāng)?shù)剡x取其許用應(yīng)力,對于用于傳遞轉(zhuǎn)矩的軸應(yīng)按扭轉(zhuǎn)強(qiáng)度條件計(jì)算,對于只受彎矩的軸(心軸)應(yīng)按彎曲強(qiáng)度條件計(jì)算,兩者都具備的按疲勞強(qiáng)度條件進(jìn)行精確校核等。 圖33軸的受力分析和彎扭矩圖求作用在齒輪上的力: (3-17) 畫軸的受力簡圖 見圖33計(jì)算軸的支承反力在水平面上 (3-18) (3-19)在垂直面上 (3-20)畫彎矩圖 見圖33在水平面上,剖面左側(cè) (3-21)剖面右側(cè) (3-21)在垂直面上 (3-22)合成彎矩,剖面左側(cè) (3-23)剖面右側(cè) (3-24)畫轉(zhuǎn)矩圖 見圖33 (3-25)判斷危險(xiǎn)截面 截面左右的合成彎矩左側(cè)相對右側(cè)大些,扭矩為T,則判斷左側(cè)為危險(xiǎn)截面,只要左側(cè)滿足強(qiáng)度校核就行了。軸的彎扭合成強(qiáng)度校核許用彎曲應(yīng)力, 截面左側(cè) (3-26) (3-27)c.軸的疲勞強(qiáng)度安全系數(shù)校核查得抗拉強(qiáng)度 ,彎曲疲勞強(qiáng)度,剪切疲勞極限,等效系數(shù), 截面左側(cè) (3-28)查得,;查得絕對尺寸系數(shù),;軸經(jīng)磨削加工,表面質(zhì)量系數(shù)。則彎曲應(yīng)力 , (3-29) 應(yīng)力幅 平均應(yīng)力 切應(yīng)力 (3-30) 安全系數(shù) (3-31) (3-32) (3-33)查許用安全系數(shù),顯然,則剖面安全。其它軸用相同方法計(jì)算,結(jié)果都滿足要求。B.中間軸設(shè)計(jì)此軸傳遞扭矩,轉(zhuǎn)速,傳遞功率為,則 (3-34)安裝軸承部分軸徑最小,由于整個(gè)軸上零件較復(fù)雜,在兩軸承之間有車在軸上的齒輪,還有安裝在軸上的小齒輪,以及軸套和軸承,所以可取大一點(diǎn),這里取,軸承部分,軸承選為單列角接觸球軸承,軸承型號為 滾動軸承7206AC,其余根據(jù)結(jié)構(gòu)確定.由于載荷不大,軸承選的較大,強(qiáng)度足夠,這里不再詳算。中間軸大體結(jié)構(gòu)及尺寸如圖3-4所示。圖3-4中間軸結(jié)構(gòu)圖C. 主軸的設(shè)計(jì)主軸是連接腰關(guān)節(jié)與大臂的結(jié)構(gòu),因結(jié)構(gòu)體積比較大,為節(jié)省材料減輕重量,故需設(shè)計(jì)成空心軸,主要承受軸向拉力,取內(nèi)徑,外徑,用圓錐滾子軸承支承,軸承型號為 滾動軸承30205。主軸材料選用型號為ZAlCu5Mn的鑄鋁合金。3.4 確定齒輪的參數(shù)3.4.1選擇材料根據(jù)表7-1,選擇齒輪的材料為45鋼,經(jīng)調(diào)質(zhì)硬度HBS可達(dá)229286。3.4.2 壓力角的選擇由機(jī)械原理知識可知,增大壓力角,能使輪齒的齒厚和節(jié)點(diǎn)處的齒廓曲率半徑增大,可提高齒輪的彎曲疲勞強(qiáng)度和接觸疲勞強(qiáng)度。此處,壓力角可取20。3.4.3 齒數(shù)和模數(shù)的選擇 對軟齒面的閉式齒輪傳動,其承載能力主要取決于齒面接觸疲勞強(qiáng)度。而齒面接觸應(yīng)力的大小與小齒輪的分度圓直徑有關(guān),即與齒數(shù)和模數(shù)的積有關(guān)。因此在滿足彎曲疲勞強(qiáng)度的前提下,宜選擇較小的模數(shù)和較多的齒數(shù)。這樣除能增大重合度,改善傳動的平穩(wěn)性外,還因模數(shù)的減小而降低齒高,從而減小金屬的切削量,減少滑動速度,減少磨損,提高抗膠合能力。軸上齒輪齒數(shù)取25,小齒輪齒數(shù)取100,軸上軸齒輪齒數(shù)取25,大齒輪齒數(shù)取300,模數(shù)m取2。3.4.4齒寬系數(shù) 由強(qiáng)度公式可知,當(dāng)載荷一定時(shí),增大齒寬可以減小齒輪直徑,降低齒輪圓周速度。但增大齒寬,齒面上的載荷分布不均勻性也將增大。查表7-7,中間軸上的齒輪與大齒輪嚙合時(shí)取齒寬系數(shù)為1.0;懸臂上的齒輪與小齒輪嚙合時(shí)取為0.5。根據(jù)公式 ,計(jì)算結(jié)果圓整為5的整數(shù)倍,作為大齒輪的齒寬,小齒輪齒寬取,以補(bǔ)償加工裝配誤差。所以軸上齒輪 與之嚙合的小齒輪齒寬 軸上的齒輪齒寬 ,與之嚙合的大齒輪齒寬3.4.5 確定齒輪傳動的精度 根據(jù)GB10095-1988規(guī)定,齒輪精度等級分為12級,1級最高,12級最低,常用69級。根據(jù)表7-8 選用7級精度的齒輪。表3-2 第一級嚙合齒輪的幾何尺寸名稱符號公式分度圓直徑齒頂高齒根高齒全高 齒頂圓直徑 齒根圓直徑 基圓直徑 齒距齒厚齒槽寬中心距頂隙表3-3 第二級嚙合齒輪的幾何尺寸名稱符號公式分度圓直徑齒頂高齒根高齒全高 齒頂圓直徑 齒根圓直徑 基圓直徑 齒距齒厚齒槽寬中心距頂隙3.4.6 齒輪的校核已選定齒輪采用45鋼,鍛造毛坯,軟齒面,齒輪滲碳淬火HRC5662,齒輪精度用7級,軟齒表面粗糙度為,對于需校核的一對的齒輪,齒數(shù)分別為,模數(shù)為2,傳動比,扭矩T=16.76Nm。a.設(shè)計(jì)準(zhǔn)則 按齒面接觸疲勞強(qiáng)度設(shè)計(jì),再按齒根彎曲疲勞強(qiáng)度校核。b.按齒面接觸疲勞強(qiáng)度計(jì)算 。 (3-35)式中:節(jié)點(diǎn)區(qū)域系數(shù),用來考慮節(jié)點(diǎn)齒廓形狀對接觸應(yīng)力的影響,取=2.5; 材料系數(shù),單位為,查表7-5,取189.8; 重合度系數(shù),取=0.90; 齒寬系數(shù),取=1; u齒數(shù)比,其值為大齒輪齒數(shù)與小齒輪齒數(shù)之比,u=12。選擇材料的接觸疲勞極限應(yīng)力為: 選擇齒根彎曲疲勞極限應(yīng)力為: 應(yīng)力循環(huán)次數(shù)N計(jì)算可得 437.5163008=10.08 (3-36)則 (3-37)查得接觸疲勞壽命系數(shù)為查得彎曲疲勞壽命系數(shù)為查得接觸疲勞安全系數(shù),彎曲疲勞安全系數(shù),又為試驗(yàn)齒輪的應(yīng)力修正系數(shù),按國家標(biāo)準(zhǔn)取2.0,試選1.3,求許用接觸應(yīng)力和許用彎曲應(yīng)力: (3-38) (3-39) (3-40) (3-41)將有關(guān)值帶入公式(3-35)得:= =29.78mm則 (3-42) (3-43)查圖得;查得,查得,取,則 (3-44)修正,mm取標(biāo)準(zhǔn)模數(shù)m=2mm,與前面選定的模數(shù)相同,所以m=2mm符合要求。c.計(jì)算幾何尺寸 , (3-45) , (3-46)d.校核齒根彎曲疲勞強(qiáng)度 查得,取校核兩齒輪的彎曲強(qiáng)度 (3-47) (3-48) 所以齒輪完全達(dá)到要求。圖3-5 大齒輪結(jié)構(gòu)圖圖3-6 小齒輪結(jié)構(gòu)圖3.5 殼體設(shè)計(jì)基座部分采用球墨鑄鐵材料,方形結(jié)構(gòu),壁厚在15mm左右。立柱采用鑄鋁,空心圓柱形狀,起固定軸承外圈的作用。其他部分具體尺寸由結(jié)構(gòu)確定,這里不一一敘述,詳見圖紙。 3.6小結(jié)本章針對腰部的齒輪、大齒輪軸、小齒輪軸進(jìn)行了設(shè)計(jì)和校核,另外還表述了設(shè)計(jì)上的見解。通過校核可知設(shè)計(jì)的齒輪、軸均符合強(qiáng)度要求???結(jié)我國機(jī)器人的研究和應(yīng)用起步較晚,但是隨著國內(nèi)外機(jī)器人的快速發(fā)展、社會需求的增大和技術(shù)的進(jìn)步,焊接機(jī)器人得到了迅速的發(fā)展,多品種、少批量生產(chǎn)方式和為提高產(chǎn)品質(zhì)量及生產(chǎn)效率的生產(chǎn)工藝需求,是推動裝焊接機(jī)器人發(fā)展的直接動力。機(jī)器人在輕型、較簡單且要求機(jī)器人價(jià)格較低的焊接作業(yè)中大顯了身手。本課題正是在這種背景下提出來的,這是一項(xiàng)具有重要意義的課題。本文主要完成了如下工作:進(jìn)行了機(jī)器人總體設(shè)計(jì)及腰關(guān)節(jié)的詳細(xì)設(shè)計(jì)機(jī)器人應(yīng)該具有外形簡單、傳動原理簡單等特點(diǎn),為此機(jī)器人設(shè)計(jì)成具有六自由度的結(jié)構(gòu),由機(jī)身、大臂、小臂、腕部組成。六個(gè)自由度均為旋轉(zhuǎn)關(guān)節(jié)。機(jī)器人六個(gè)關(guān)節(jié)均選直流電機(jī)驅(qū)動。第一個(gè)關(guān)節(jié)采用二級齒輪傳動,這種傳動方式具有精度高、定位安裝方便等優(yōu)點(diǎn);其他五個(gè)關(guān)節(jié)都采用了錐齒輪與直齒輪的傳動結(jié)構(gòu),充分利用了大臂和小臂的空間,結(jié)構(gòu)緊湊。參考文獻(xiàn)1 汪愷. 機(jī)械設(shè)計(jì)標(biāo)準(zhǔn)應(yīng)用手冊M. 機(jī)械工業(yè)出版社. 1997.8.2 成大先. 機(jī)械設(shè)計(jì)手冊M. 化學(xué)工業(yè)出版社 2002.1.3 徐灝. 機(jī)械設(shè)計(jì)手冊M. 北京:機(jī)械工業(yè)出版社 2002.4 徐錦康. 機(jī)械設(shè)計(jì)M .機(jī)械工業(yè)出版社 2001.5 殷際英,何廣平.機(jī)器人M. 北京:化學(xué)工業(yè)出版社 2003.6 周伯英. 工業(yè)機(jī)器人設(shè)計(jì)M. 北京:機(jī)械工業(yè)出版社 1995.7 陳秀寧,施高義.機(jī)械設(shè)計(jì)課程設(shè)計(jì)M.浙江大學(xué)出版社 1995.8.8 王宗榮.工程圖學(xué)M.機(jī)械工業(yè)出版社 2001.9.9 費(fèi)仁元,張慧慧.機(jī)器人設(shè)計(jì)和分析M.北京工業(yè)大學(xué)出版社 1998.9.10 龔振邦.機(jī)器人機(jī)械設(shè)計(jì)M.北京:電子工業(yè)出版社 1995.11.11 吳相憲,王正為,黃玉堂.實(shí)用機(jī)械設(shè)計(jì)手冊M.中國礦業(yè)大學(xué)出版社 1993.5.12 龐啟淮.小功率電動機(jī)應(yīng)用技術(shù)手冊M.機(jī)械工業(yè)出版社.13 馬香峰.工業(yè)機(jī)器人的操作機(jī)設(shè)計(jì)M.冶金工業(yè)出版社.編號: 畢業(yè)設(shè)計(jì)(論文)外文翻譯(原文)題 目:Dynamic load analysis and Design methodology of LCD transfer robot院 (系): 機(jī)電工程學(xué)院 專 業(yè):機(jī)械設(shè)計(jì)制造及其自動化學(xué)生姓名: 呂 強(qiáng) 學(xué) 號: 1000110125 指導(dǎo)教師單位: 機(jī)電工程學(xué)院 姓 名: 唐 焱 職 稱: 副教授 題目類型:理論研究 實(shí)驗(yàn)研究 工程設(shè)計(jì) 工程技術(shù)研究 軟件開發(fā) 2014年5月25日Dynamic load analysis and design methodology of LCD transfer robotJong Hwi Seo1, Hong Jae Yim2,*, Jae Chul Hwang1, Yong Won Choi1 and Dong Il Kim 11Robotics Technology Lab, Mechatronics & Manufacturing Technology CenterSAMSUNG Electronics Co., LTD. Suwon, South Korea2School of Mechanical and Manufacturing Engineering, Kookmin University SeongBuk-Gu, Seoul, South Korea(Manuscript Received July 20, 2007; Revised December 28, 2007; Accepted January 16, 2008)AbstractThe objective of the present study is to develop a design methodology for the large scale heavy duty robot to meet the design requirements of vibration and stress levels in structural components resulting from exposure of system modules to LCD (Liquid Crystal Display) processing environments. Vibrations of the component structures significantly influence the motion accuracy and fatigue damage. To analyze and design a heavy duty robot for LCD transfer, FE and multi-body dynamic simulation techniques have been used. The links of a robot are modeled as flexible bodies using modal coordinates. Nonlinear mechanical properties such as friction, compliance of reducers and bearings were considered in the flexible multi-body dynamics model. Various design proposals are investigated to improve structural design performances by using the dynamic simulation model. Design sensitivity analyses with respect to vibration and stresses are carried out to search an optimal design. An example of an 8G (8th-Generation) LTR (LCD Transfer Robot) is illustrated to demonstrate the proposed methodology. Finally, the results are verified by real experiments including vibration testing.Keywords: Flexible multibody dynamics; LTR (LCD Transfer Robot); Vibration fatigue1. IntroductionLCDs are widely used in TVs, computers, mobile phones, etc., because they offer some real advantages over other display technologies. They are thinner and lighter and draw much less power. Recently, the size of raw glass has greatly increased in new generation LCD (Liquid Crystal Display) technology. In order to handle bigger and heavier glasses, it is necessary to develop a large scale LTR (LCD transfer robot) to support various complicated LCD fabrication processes.It will cause many difficult design problems such as vibration, handling accuracy deterioration and high stresses due to heavier dynamic loads, resultingin inaccurate transfer motion and fatigue cracks. Therefore, it is necessary to establish a methodology for predicting deflections, vibrations, and dynamic stress time histories using virtual computer simulation models. An integrated design simulation method would be useful to validate a baseline design and to propose new improved designs. In this paper an integratedcomputer simulation methodology is presented to predict deflections, dynamic stresses due to vibrations design, based on the existing FEM and flexible body dynamics technology.The proposed methodology is applied to the LTR that handles 7G/8G LCD glasses. Vibration analysis is performed and validated with the vibration modal test to identify and to recapture the inherent phenomenon in the system. Some flexible components in the LTR may experience severe vibration to cause fatigue damage due to large dynamic loads. Modal characteristics are used to consider structural flexibility in flexible multi-body dynamic simulations. Tip deflection of the end-effecter can be calculated to see if design requirements are met. Dynamic loads and dynamic stress histories can be obtained from the dynamic simulation. Stress levels are investigated at the critical areas to predict if fatigue cracks might occur. If the stress level is not in a safe region, design change should be made based on the computer simulation results and design sensitivity study. Then a prototype LTR is built and tested for design validation.The present paper describes the CAE-based durability analysis that is being implemented and developed at SAMSUNG, to predict fatigue damage corresponding to durability tests. The proposed methodology can be used to develop a new large scale LTR robot in the early design stage.2. Introduction of LCD-transfer robotFig. 1 shows various types of LTRs. Telescope type LTR consists of a base frame, an R-frame, two Z-frames, two articulated arms with slender hands as shown in Fig. 1(a). The frame structures are fabricated with cast iron and aluminium. Hands with slender fingers are made of lightweight composite materials.It also has two arms (upper and lower arms) to handle two glasses simultaneously. The LTR has a cylindrical workspace to transfer glasses for various fabrication processes. For precision control of handling the glasses, static deformation at the tip of the finger must be less than 10 mm. Since the joints which connect the arms and links include bearings and reducers, joint compliance must be considered to predict the static deformation at the tip. Flexibilities of the arm itself are also important to both static and dynamic deformation, because the arm is a kind of cantilever type structure with a large lumped mass at the tip.LTR is supposed to repeat millions of cycles to perform LCD fabrication processes in real life. Therefore, it has to pass physical tests to ensure the survivability of the robot system when subjected to static and cyclic loadings. The durability test involves a cyclic loading apparatus that evaluates the durability characteristics of the component structure. Among the many different tests, one of the most critical is the hand motion of stretching out and pulling in with the zframes vertical motion. The critical motion simulates the jerking and twisting impact that an arm support bracket might experience when running with large glasses loaded. The arms and hands are synchronized and moved at a speed of about 4 m/s.(a) Telescopic type(b) Gate type(c) Link typeFig. 1. LCD Transfer robots (LTR).Since the LTR repeats millions of cycles of particular loading and unloading with various configurations,it may result in fatigue failure at a critical stress area.In this paper, to predict static and dynamic deformation at the tip of the finger and critical stress levels including vibration of the LTR, flexible multi-body dynamic simulations are presented. Link-frames,arms are modelled as flexible bodies. Static and dynamic deformation is assumed to be very small, therefore,within the linear elastic range. To represent the flexibility, vibration normal modes and static correction modes are obtained from the finite element vibration and static analysis for each flexible component.To represent the joint compliance, spring and damper force elements are used instead of kinematic joint elements 1.3. Flexible multi-body dynamicsThe main advantage of using modal coordinates in flexible multi-body dynamics is the reduction in the number of generalized coordinates that must be included in the analysis. Two types of modes are used in component mode synthesis for flexible multi-body dynamics 1, 2. One is a normal mode. The other is a static mode. All used normal modes and static modes must be normalized to have the same magnitude and be orthogonalized to be independent to each other.3.1 Kinematics of flexible componentsA typical flexible component is shown in Fig. 2. The flexible component i is discretized into a large number of finite elements. The global position of a point p in a flexible part i can be represented asWhere is the global position vector of the X-Y-Z body reference frame, is the coordinate transformation matrix from the body reference frame to the global inertial frame, is the initial position vector of the point p from the body reference frame, and is the displacement vector due to deformation.The displacement vector can be approximated by a linear combination of deformation modes like Eq. (2). Whereis a modal matrix and is the corresponding deformation mode of a flexible part i. is a 6N1 modalvector and is modal coordinates, M is the number of modal coordinates. The deformation modes can be normal modes, static modes, or combination of normal and static modes. Used M modes should be linearly independent to each other.3.2 Flexible multi-body dynamic equationsAs shown in Fig. 2, the nodal position vector of a typical point p in the global reference frame can thus be written as Eq. (3) by using Eq. (2)Where and the rotational displacementi of nodal point p is defined by . The combined set of kinematic and driving constraints of the multi-body dynamic system may be written in the form 3, 4Where the generalized coordinates ,t is the time, is the constraint equation. Using the Lagrange Multiplier Theorem, variational equations of motion of the multi-body system may be obtained by summing all bodies and constraints in the system as in the matrix form of Eq.This is a mixed system of differential-algebraic equations of motion for considering the elastic effect of the mechanical system. To solve mixed differential algebraic equations, many numerical algorithms have been developed 3. Using Eq. (5), dynamic stress history of a flexible component can be calculated 5.4. Dynamic modelling of an lcd-transfer robotThe 8G-Telescopic type LTR system shown in Fig.Fig. 3. Flexible multi-body dynamics model for 8G-TelescopicLTR.Fig. 4. Dynamic modeling of LTR arm system1(a) can be modeled with 86 rigid bodies, 30 flexible bodies, kinematic joints, and force elements 3. The flexible bodies considered in the multi-body dynamic simulation are named in the Fig. 1(a). Fig. 3 shows the flexible multi-body simulation model for 8GTelescopic LTR.For parallel rectilinear motion of the finger and hand-bracket, a timing belt at each arm system is modeled to drive at constant speed ratio. As shown in Fig. 4, to represent the elasticity and damping of the belt, spring and damping forces are approximated to be proportional to displacement and velocity of the belt length change. Even the joint compliances for bearing and reducers are modeled in a similar way with rotational-spring and damper elements. The experimental values from the components makers are shown in Table 1.Major components such as arms and link frames are made of cast iron or cast aluminium. Those structural components can be assumed to be linear elastic during normal operation. However, such a small elastic deformation may cause vibration and repeated dynamic stresses resulting in inaccurate transfer motion and fatigue cracks. Therefore, it is necessary to establish a methodology for predicting the deformation, vibration, and dynamic stress time histories with a virtual computer simulation model.Component mode synthesis technique 1-4, explained in the previous section, can be used for efficient computer simulation in large rigid body gross motion with small elastic deformation. Since the component mode synthesis method employs modal coordinates to consider the elastic deformation of flexible bodies, it is possible to execute a large multibodydynamic system analysis more effectively by using a small number of well-selected modes.Fig. 5 shows the 1st vibration modes of flexible components in the telescopic LTR in Fig. 1(a). Also,Fig. 5 shows a typical component mode and the number of modes used in the mode component synthesis method for the flexible multi-body dynamic analysis.Table 1. Joint stiffness for bearing and reducers.NoAxialStiffness RadialStiffness Part1180 KNm/rad2570 KNm/radReducer2250 KNm/rad3510 KNm/radReducer367 KNm/rad1000 KNm/radReducer46745 KNm/rad43840 KNm/radReducer50436360 KNm/radBearing(a) Finger (36) (c) Arm-Frame (42) (d) Z1-Frame (24) (e) Z2-Frame (24) (f) R-Frame (36)Fig. 5. Component modes of flexible bodies (number ofmodes used for dynamic simulation).5. Analysis and design improvement of LTR5.1. Modal analysis of 8G-telescopic LTRSince major structural bodies such as arms and link-frames are modelled as flexible bodies, the proper kinematic joints and force elements, fundamental vibration modes of the total LTR system can be investigated. The modes calculated from the vibration analysis can be used for searching for the structural weak point and used for the flexible multi-body dynamic simulation explained in the previous chapter. Fig. 6 shows the modal deformation from the vibration test of the LTR system. Analytical vibration modes calculated from the dynamic simulation model are compared with the experimental test results for validation. Comparison with the modal test results showed that simulation results correlate well with the test results. From the results of the analytical and experimental modal deformation, we found that the structural weak point was the R-frame. This information was very important to reduce the system vibration,as explained in the following section.5.2 Vibration analysis and design improvementDesign problems such as tip deflection and fatigue crack can be investigated with a valid simulation model. Among the various process events for LCD glass transfer motion, stretching out and pulling in motions of the hands with glass loaded are the most critical motions to cause severe vibration and high stresses at the supporting bracket structure. Using the proposed flexible multi-body simulation technology, the critical motion is regenerated to investigate how large deflection and stresses occur during the operation. Since we have a valid simulation model, we can investigate various design proposals.After the prototype robot was developed, undesirable vibration at the measure point was observed when the robot was running onto the guide rail, as shown in Fig. 7. The cause of the vibration was the insufficient stiffness of the R-frame, studying from the analysis of the system modal deformation, as explained in the previous section. In other words, the Rframe at the base of the LTR was known to be a critical component for the vibration.To increase bending and twisting stiffness, height and width of the beam cross section was enlarged,and ribs were added as explained in the Fig. 7. Even aluminium material is replaced with high strength steel to increase the elastic modulus. To verify the design modification, a dynamic simulation model was used. Fig. 6. Vibration modes by experiment and comparison of frequenciesFig. 7. Design study to reduce the vibration by dynamics simulation.Fig. 8. Comparison of vibration levels between the original and modified design. Fig. 9. An example of the crack fatigue.Fig. 8 shows a comparison of vibration displacements during the simulated motions between the original baseline design and the new improved design. More than 50% reduction of the vibration level is observed during the critical motion period from 5 to 10 seconds even at the prototype test as shown in Fig. 8.5.3 Stress analysis and design improvementAs the size of raw glass tends to become larger for productivity and manufacturing cost competitiveness,LTR robots need to be faster and bigger to handle the larger and heavier glasses with higher speed. This may result in increased dynamic loads causing fatiguecracks due to dynamic stresses.Fig. 9 shows an example of the fatigue cracks due to dynamic loads at the supporting arm-frame structure in the 7G-Gate LTR shown in Fig. 1(b). Using the flexible multi-body dynamic simulation, cause and effect for the fatigue crack can be analyzed prior to adoption in an actual spot. To reduce the level of dynamic stress at the critical area, the shape andthickness of the structure must be redesigned based on the validated simulation model. Experimental tests were executed to validate the accuracy of dynamic stresses predicted in virtual computer simulations, as shown in Fig. 10. And the result was exactly the sameas the point of occurrence of the crack. Fig. 11 shows the design modification. To reduce the stress concentration, the rectangular shape with sharp corners was changed to a round shape, and ribs were changed.Fig. 12 shows a comparison of maximum dynamic stresses between the modified shape and original shape with different metal thickness. The stress measure point of the part is the dotted circle area in the Fig. 10. This result shows the conclusion that the design was reasonably modified. Practically, the modified design was adopted for the 7G-Gate LTR in the actual spot. Fig. 10. Strain experiment and dynamic analysis for fatigue life prediction.Fig. 11. Design modification for avoiding stress concentration.Fig. 12. Stress analysis and design improvement5.4 Handling accuracy and design optimizationIf dynamic loads are increased, it might deteriorate the accuracy of the precision transfer motion due to deflection and deformation of major structural components 6. Fig. 13 shows the vertical deflections at the tip points of the fingers for the baseline design of the 8G-Telecscopic LTR.The tip deflection of the original design of the LTR was 42 mm. This exceeds the design specification requirement of 10 mm for the LCD fabrication process,and may be the cause of the collision between cassette and robot hands. The cause of the deflection was that the robot structure was very large and heavy. As a result, the deflection must be reduced and the transfer accuracy improved by using the dynamic simulation and optimized design techniques. To reduce the dynamic deflection, a thin-tapered circular plate, what we called a liner, was used, as shown in Fig. 14.The combination of the three liners thickness is very important to reduce the deflection and to optimize the transfer accuracy. So we used dynamic simulations and D.O.E (Design of experiment) for optimization. Fig. 15 shows the proposed simulation methodology which can be used to minimize the deflection at the tip of the finger. The object function was minimization of the differences of the vertical z-displacement of 4-points in Fig.13. The used D.O.E table was a central composite design table with 3-levels and 3-factors 7. Table 2 shows the regression analysis result (ANOVA table).Through the response surface model calculated from the regression analysis 7, the optimized liner thickness was t1=0.50, t2=0.48, t3=0.78 mm. The simulation results for the optimized variable (liner thickness) are shown in Fig. 16. The deflection was reduced only to 5.8 mm. But 42 mm deflection occurred in the baseline design as shown in Fig. 13.An experimental test using the laser tracker was carried out to validate the optimized simulation result.As shown in Fig. 17, the experimental result was about 6.1mm.The simulation results of dynamic deflection were very similar to the test results. This means that we reinforced the structural stiffness without any additional expense.Fig. 13. Vertical deflection of the fingers for baseline designFig. 14. Robot arm and liner (thin circular plate).Fig. 15. Process for design variable optimization.Table 2. ANOVA table for optimization. Fig. 16. Optimized design result using dynamic simulation and D.O.E.6. ConclusionsA computer simulation methodology was presented for vibration and fatigue analysis of the LTR system.Variable amplitude multi-axial loading conditions can be generated to investigate any structural deflection, vibration, and dynamic stress. Flexible bodies were modelled by using component mode synthesis technique.To represent joint compliance and
收藏