升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì)
升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì),升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì),升降,舞臺(tái),液壓,系統(tǒng),設(shè)計(jì)
河南理工大學(xué)本科畢業(yè)設(shè)計(jì)(論文)中期檢查表指導(dǎo)教師: 職稱: 講 師 所在院(系): 機(jī)械與動(dòng)力工程學(xué)院 教研室(研究室): 機(jī)械設(shè)計(jì)教研室題 目升降舞臺(tái)的設(shè)計(jì)學(xué) 生姓 名專業(yè)班級(jí)學(xué)號(hào)一、選題質(zhì)量:(主要從以下四個(gè)方面填寫:1、選題是否符合專業(yè)培養(yǎng)目標(biāo),能否體現(xiàn)綜合訓(xùn)練要求;2、題目難易程度;3、題目工作量;4、題目與生產(chǎn)、科研、經(jīng)濟(jì)、社會(huì)、文化及實(shí)驗(yàn)室建設(shè)等實(shí)際的結(jié)合程度)(1)本課題符合專業(yè)培養(yǎng)的目標(biāo),通過設(shè)計(jì),可以鞏固所學(xué)的專業(yè)知識(shí),提高了綜合訓(xùn)練要求。(2)本課題偏難,但在所掌握的專業(yè)知識(shí)情況下,還可以完成設(shè)計(jì)目標(biāo)。(3)本課題工作量符合本科畢業(yè)生設(shè)計(jì)的要求。 (4)本課題在老師的指導(dǎo)下,和學(xué)生自己的努力下有一定可研究性。二、開題報(bào)告完成情況:在指導(dǎo)老師的指導(dǎo)下,設(shè)計(jì)者獨(dú)立按時(shí)完成了開題報(bào)告。三、階段性成果:(1)第一階段(前6周):搜集升降舞臺(tái)的相關(guān)資料。(2)第二階段(第7周):完成了相關(guān)的英文翻譯工作。(3)第三階段(第89周):完成了對(duì)升降舞臺(tái)的結(jié)構(gòu)分析及數(shù)據(jù)計(jì)算。(4)第四階段(第1011周):對(duì)升降舞臺(tái)進(jìn)行數(shù)據(jù)整理,并繪制相關(guān)圖。(5)第五階段(12周):完成設(shè)計(jì)說明書。(6)第六階段(13周):進(jìn)行設(shè)計(jì)說明書的工作。四、存在主要問題:(1)起初不能對(duì)升降舞臺(tái)有明確的認(rèn)識(shí)。在指導(dǎo)老師的指導(dǎo)下,以及在相關(guān)資料的輔助下,逐漸明白。(2)在英文翻譯過程中,不懂一些術(shù)語,以至不能正確翻譯其意思。通過閱有關(guān)資料以及詢問,能夠按時(shí)保質(zhì)地完成翻譯工作。(3)在繪圖過程中,遇到一些不懂的地方比如一些標(biāo)注的標(biāo)法,及一些零件的標(biāo)準(zhǔn)繪制經(jīng)查資料已解決。五、指導(dǎo)教師對(duì)學(xué)生在畢業(yè)實(shí)習(xí)中,勞動(dòng)、學(xué)習(xí)紀(jì)律及畢業(yè)設(shè)計(jì)(論文)進(jìn)展等方面的評(píng)語:指導(dǎo)教師: (簽名) 年 月 日河南理工大學(xué)畢業(yè)設(shè)計(jì)說明書前 言本次畢業(yè)設(shè)計(jì)是我們大學(xué)四年的最后一次設(shè)計(jì),同時(shí)也是對(duì)大學(xué)生四年來所學(xué)的知識(shí)系統(tǒng)總結(jié)和綜合應(yīng)用?,F(xiàn)在我們已經(jīng)進(jìn)入大學(xué)學(xué)習(xí)的最后階段,畢業(yè)設(shè)計(jì)作為本科學(xué)習(xí)最重要的組成部分之一,它能提高我們發(fā)現(xiàn)、分析、解決問題的能力,綜合檢驗(yàn)和鞏固我們所學(xué)知識(shí),同時(shí)又是對(duì)我們大學(xué)四年所學(xué)知識(shí)的全面復(fù)習(xí),更是向我們以后即將從事的專業(yè)性工作的正常過渡。我們可以緊緊抓住這個(gè)機(jī)會(huì)認(rèn)真學(xué)習(xí)并搞好畢業(yè)設(shè)計(jì),眾所周知,它對(duì)我們即將走上工作崗位或者更進(jìn)一步深造有非常重要的意義。它將把我們過去的理論學(xué)習(xí)引向一個(gè)更高、更深的層次,也就是參加工作,可以說我們?cè)谧鲆淮芜^渡性的嘗試。畢業(yè)設(shè)計(jì)是我在接受高等教育中的最后一次綜合性的實(shí)踐學(xué)習(xí),是實(shí)現(xiàn)學(xué)生綜合運(yùn)用知識(shí)的能力,是實(shí)現(xiàn)培養(yǎng)目標(biāo)、培養(yǎng)學(xué)生專業(yè)工作能力、提高學(xué)生綜合素質(zhì)的重要手段。當(dāng)然,畢業(yè)設(shè)計(jì)成果的質(zhì)量,也是學(xué)生畢業(yè)資格認(rèn)定的一個(gè)重要依據(jù),是對(duì)學(xué)校人才培養(yǎng)效果的全面檢驗(yàn),是學(xué)校教育教學(xué)質(zhì)量評(píng)價(jià)的重要內(nèi)容。畢業(yè)設(shè)計(jì)的目的主要是:(1)培養(yǎng)學(xué)生創(chuàng)造性地綜合運(yùn)用所學(xué)基本理論和技能,獨(dú)立完成本專業(yè)范圍內(nèi)工程設(shè)計(jì)或?qū)嶒?yàn)分析的專業(yè)工作能力;(2)學(xué)習(xí)科學(xué)的精神和創(chuàng)新能力;(3)學(xué)習(xí)調(diào)查研究、收集處理信息和查閱文獻(xiàn)的能力;(4)學(xué)習(xí)語言表達(dá)和撰寫科技報(bào)告(論文)的能力;(5)培養(yǎng)學(xué)生的效益意識(shí)、全局觀念和團(tuán)隊(duì)協(xié)作精神。在此基礎(chǔ)上,通過畢業(yè)設(shè)計(jì),培養(yǎng)學(xué)生的整體構(gòu)建設(shè)計(jì)的能力,全面的去考慮問題,幫助我們掌握工程設(shè)計(jì)中的一般產(chǎn)品設(shè)計(jì)的程序和方法。為我們?cè)谝院蟮膶?shí)際工作中,能更好的解決工程實(shí)際生產(chǎn)中遇到的實(shí)際問題打下堅(jiān)實(shí)的基礎(chǔ),而且還有助于我們分析問題和創(chuàng)造性的解決問題的能力,全面提高我們的素質(zhì)。畢業(yè)設(shè)計(jì)教學(xué)基本要求主要是通過畢業(yè)設(shè)計(jì),將思想道德素質(zhì)教育、業(yè)務(wù)素質(zhì)教育、文化素質(zhì)教育于一體,注重學(xué)生素質(zhì)的全面提高,以達(dá)到培養(yǎng)目標(biāo)的基本要求;注重培養(yǎng)學(xué)生嚴(yán)肅認(rèn)真的工作態(tài)度、勤奮鉆研的優(yōu)良學(xué)風(fēng)和獨(dú)立工作能力;注重開發(fā)學(xué)生的創(chuàng)新精神和創(chuàng)造能力,實(shí)現(xiàn)畢業(yè)設(shè)計(jì)的教學(xué)目的。我所選擇的畢業(yè)設(shè)計(jì)題目升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì)。由于升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì)要求很高,設(shè)計(jì)環(huán)節(jié)較多,而且我缺乏實(shí)際經(jīng)驗(yàn),再加上由于國內(nèi)升降舞臺(tái)的發(fā)展較晚關(guān)于升降舞臺(tái)的系統(tǒng)地、實(shí)際地、具有一定理論指導(dǎo)作用的專業(yè)書籍很少,所以在設(shè)計(jì)中存在很多的不足和疏漏,懇請(qǐng)老師和同學(xué)批評(píng)指正。1緒論1.1液壓傳動(dòng)發(fā)展概況液壓傳動(dòng)相對(duì)于機(jī)械傳動(dòng)來說,是一門發(fā)展較晚的技術(shù)。從17世紀(jì)中葉巴斯卡提出靜壓傳遞原理、18世紀(jì)末英國制成第一臺(tái)水壓機(jī)算起,液壓傳動(dòng)只有二三百年的歷史。19世紀(jì)末德國制成了液壓龍門刨床,美國制成了液壓轉(zhuǎn)塔車床和磨床。由于缺乏成熟的液壓元件,一些通用機(jī)床到20世紀(jì)30年代才用上了液壓傳動(dòng)。第二次世界大戰(zhàn)期間,由于軍事工業(yè)需要反應(yīng)快、動(dòng)作準(zhǔn)確的自動(dòng)控制系統(tǒng),促進(jìn)廠液壓技術(shù)的發(fā)展。戰(zhàn)后液壓技術(shù)迅速轉(zhuǎn)向民用。隨著工業(yè)水平的不斷提高,各種液壓九件的研制不斷完善井實(shí)現(xiàn)了各類元件產(chǎn)品的標(biāo)準(zhǔn)化、系列化和通用化,從而使它在機(jī)械制造、上程機(jī)械、農(nóng)業(yè)機(jī)械、汽車制造等行業(yè)得到推廣應(yīng)用。20世紀(jì)60年代以來,隨著原子能、空間技術(shù)、計(jì)算機(jī)技術(shù)的發(fā)展,液壓技術(shù)得到了很大的發(fā)展并滲透到各個(gè)工業(yè)領(lǐng)域中。液壓技術(shù)開始向高壓、高速、大功率、南效率、低噪聲、低能耗、經(jīng)久耐用、高度集成化等方向發(fā)展。從20世紀(jì)70年代開始,電子技術(shù)和計(jì)算機(jī)技術(shù)迅速發(fā)展井進(jìn)入了液壓技術(shù)領(lǐng)域,在產(chǎn)品設(shè)計(jì)、制造和測試方面采用廠這些先進(jìn)技術(shù),取得了顯著的效益。利用計(jì)算機(jī)輔助進(jìn)行液壓元件和液壓系統(tǒng)的設(shè)計(jì)計(jì)算、性能仿真、自動(dòng)繪圖以及數(shù)據(jù)的采集和處理,可提高液壓產(chǎn)品的質(zhì)量,優(yōu)化其性能,降低成本,并大大縮短其生產(chǎn)和交貨周期。在設(shè)備控制方面,利用計(jì)算機(jī)控制液壓系統(tǒng),可簡化操作提高勞動(dòng)生產(chǎn)率,提高自動(dòng)化水平,井增加產(chǎn)品的可靠性。因此,近年來,液壓行業(yè)對(duì)于計(jì)算機(jī)技術(shù)的應(yīng)用給予極大的關(guān)注,其中計(jì)算機(jī)輔助設(shè)計(jì)CAD(Computer aided design)的推廣使用和數(shù)字控制液壓元件的研制開發(fā)尤其突出。另外減小元件的體積和重量,提高元件的壽命,研制新介質(zhì)以及污染控制的研究,也是當(dāng)前液壓傳動(dòng)及液壓控制技術(shù)發(fā)展和研究的重要課題。我國的液壓工業(yè)開始于20世紀(jì)50年代,其產(chǎn)品最初只用于機(jī)床和鍛壓設(shè)備,后來又用于拖拉機(jī)和工程機(jī)械。自20世紀(jì)60年代開始,從國外引進(jìn)液壓元件生產(chǎn)技術(shù),問時(shí)自行設(shè)計(jì)液壓產(chǎn)品。我國生產(chǎn)的液壓元件已形成系列,并在各種機(jī)械設(shè)備上得到了廣泛的應(yīng)用。目前,我國在消化、推廣國外先進(jìn)液壓技術(shù)的同時(shí),大力開展國產(chǎn)液壓新產(chǎn)品的研制工作,并已取得一定成效。例如,已開發(fā)研制了中高壓齒輪泵、插裝式錐閥、電液比例閥、疊加閥以及新系列中、高壓閥等。盡管如此,我國的液壓元件和液壓產(chǎn)品與國外先進(jìn)的同類產(chǎn)品相比,在性能上,在種類、規(guī)格上仍存在著較大的差距。為了迅速趕超世界先進(jìn)水平我國已瞄準(zhǔn)世界發(fā)展主流的液壓元件系列型譜,有計(jì)劃地引進(jìn)、消化、吸收國外最先進(jìn)的液壓技術(shù)和產(chǎn)品,并對(duì)我國觀正生產(chǎn)的液壓產(chǎn)品進(jìn)行整頓,合理調(diào)整產(chǎn)品結(jié)構(gòu),大力開展產(chǎn)品國產(chǎn)化工作??梢灶A(yù)見,我國的液壓技術(shù)在21世紀(jì)必將獲得更快的發(fā)展。1.2液壓技術(shù)的應(yīng)用與特點(diǎn)1.2.1液壓技術(shù)的應(yīng)用液壓技術(shù)是涉及液體流動(dòng)和液體壓力規(guī)律的科學(xué)技術(shù)。近幾十年來,液壓技術(shù)發(fā)展非常快,廣泛應(yīng)用于工業(yè)、農(nóng)業(yè)和國防等各個(gè)部門。液壓傳動(dòng)主要應(yīng)用如下:(1)一般工業(yè)用液壓系統(tǒng):坯料加工機(jī)械(注塑機(jī))、壓力機(jī)械(鍛壓機(jī))、重型機(jī)械(廢鋼壓塊機(jī))、機(jī)床(全自動(dòng)六角車床、平面磨床)等;(2)行走機(jī)械用液壓系統(tǒng):工程機(jī)械(挖掘機(jī))、起重機(jī)械(汽車吊)、建筑機(jī)械(打樁機(jī))、農(nóng)業(yè)機(jī)械(聯(lián)合收割機(jī))、汽車(轉(zhuǎn)向器、減振器)等;(3)鋼鐵工業(yè)用液壓系統(tǒng):冶金機(jī)械(軋鋼機(jī))、提升裝置(電極升降機(jī))、軋輥調(diào)整裝置等;(4)土木工程用液壓系統(tǒng):防洪閘門及堤壩裝置(浪潮防護(hù)擋板)、河床升降裝置、橋梁操縱機(jī)構(gòu)和礦山機(jī)械(鑿巖機(jī))等:(5)發(fā)電廠用液壓系統(tǒng);渦輪機(jī)(調(diào)速裝置)、核發(fā)電廠等;(6)特殊技術(shù)用液壓系統(tǒng):巨型天線控制裝置、測量浮標(biāo)、飛機(jī)起落架的收放裝置及方向舵控制裝置、升降旋轉(zhuǎn)舞臺(tái)等;(7)船舶用液壓系統(tǒng):甲板起重機(jī)械(絞車)、船頭門、艙壁閥、船尾推進(jìn)器等;(8)軍事工業(yè)用液壓系統(tǒng):火炮操縱裝置、艦船減搖裝置、飛行器仿真等。上述的概略說明不包括所有應(yīng)用的可能性。用液壓系統(tǒng)傳遞動(dòng)力、運(yùn)動(dòng)和控制的應(yīng)用范圍相當(dāng)廣泛,它在當(dāng)今的各個(gè)領(lǐng)域中都占有一席之地。目前,液壓傳動(dòng)技術(shù)在實(shí)現(xiàn)高壓、高速、大功率、高效率、低晚聲、長壽命、高度集成化等方面都取得了很大的進(jìn)展。同時(shí),由丁它與微電子技術(shù)次緊密配合,能在盡可能小的空間內(nèi)傳送出盡可能人的功率并加以淮確地控制,從而更使得它在各行各業(yè):中發(fā)揮出廠巨大作用。在本設(shè)計(jì)中是將液壓傳動(dòng)應(yīng)用于舞臺(tái)的升降中,升降舞臺(tái)液壓系統(tǒng)是為某劇場配套而設(shè)計(jì)制造的。其升降功能由4根液壓缸頂升叉架完成, 4根液壓缸的同步由帶補(bǔ)正裝置的同步回路完成。升降臺(tái)是液壓系統(tǒng)的重要應(yīng)用領(lǐng)域,升降臺(tái)液壓系統(tǒng)也是比較成熟的技術(shù)。與機(jī)械傳動(dòng)相比,采用液壓傳動(dòng)可以大大地減少換向沖擊,降低能量消耗,井能縮短換向時(shí)間。采用液壓傳動(dòng)方式可有效利用現(xiàn)場的有限空間,盡可能地減少傳動(dòng)裝置的占地面積,可靠保證舞臺(tái)平穩(wěn)升降。液壓升降舞臺(tái)具有升降平穩(wěn)、噪音低、易于實(shí)現(xiàn)自動(dòng)化控制、可實(shí)現(xiàn)升降臺(tái)的無級(jí)調(diào)速。1.2.2液壓傳動(dòng)的特點(diǎn)液壓傳動(dòng)由于有許多特點(diǎn),才使得它被廣泛地應(yīng)用于各行行業(yè)之中。液壓傳動(dòng)相對(duì)于其它傳動(dòng)有以下些主要優(yōu)點(diǎn): (1)在同等體積下,液壓裝置能產(chǎn)生出更大的動(dòng)力。也就是說,在同等功率下,液壓裝置的體積小、重量輕、結(jié)構(gòu)緊湊,即:它具有大的功率密度或力密度,力密度在這里等于工作壓力;(2)按壓裝置容易做到對(duì)速度的無級(jí)凋節(jié),而且調(diào)速范圍大,并且對(duì)速度的調(diào)節(jié)還可以在工作過程中進(jìn)行;(3)液壓裝置工作平穩(wěn),換向沖擊小,便于實(shí)現(xiàn)頻繁換向;(4)液壓裝置易于實(shí)現(xiàn)過載保護(hù)能實(shí)現(xiàn)自潤滑,使用壽命長;(5)按壓裝置易于實(shí)現(xiàn)自動(dòng)化,可以很方便地對(duì)液體的流動(dòng)方向、壓力和流量進(jìn)行調(diào)節(jié)和控制,并能很容易地和電氣、電子控制或氣動(dòng)控制結(jié)合起來,實(shí)現(xiàn)復(fù)雜的運(yùn)動(dòng)、操作。(6)液壓元件易于實(shí)現(xiàn)系列化、標(biāo)準(zhǔn)化;和通用化,便于設(shè)計(jì)、制造和推廣使用當(dāng)然, 壓傳動(dòng)還存在以下一些明顯缺點(diǎn):(1)液壓傳動(dòng)中的泄漏和液體的可壓縮件,使這種傳動(dòng)無法保證嚴(yán)格的傳動(dòng)比;(2)液壓傳動(dòng)有較多的能量損失(泄漏損失、摩擦損失等),因此,傳動(dòng)效率相對(duì)低;(3)液壓傳動(dòng)對(duì)油溫的變化比較敏感不宜在較高或較低的溫度下工作:(4)液壓傳動(dòng)在出現(xiàn)故障時(shí)不易找出原因。1.2.3液壓系統(tǒng)的組成液壓傳動(dòng)裝置主要由以下五部分組成: 1)能源裝置把機(jī)械能轉(zhuǎn)換成油液液壓能的裝置。最常見的形式就是液壓泵,它給液壓系統(tǒng)提供壓力油。 2)執(zhí)行裝置把油液的液壓能轉(zhuǎn)換成機(jī)械能的裝置。它可以是作直線運(yùn)動(dòng)的液壓缸,也可以是作回轉(zhuǎn)運(yùn)動(dòng)的液壓馬達(dá)。 3)控制調(diào)節(jié)裝置對(duì)系統(tǒng)中油液壓力、流量或流動(dòng)方向進(jìn)行控制或調(diào)節(jié)裝置。例如溢流閥、節(jié)流閥、換向閥、開停閥等這些元件的不同組合形成了不同功能的液壓系統(tǒng)。 4)輔助裝置上述三部分以外的其它裝置,例如油箱、濾油器、油管等。它們對(duì)保證系統(tǒng)正常工作也有重要作用。5)工作介質(zhì):液壓系統(tǒng)中用量最大的工作介質(zhì)是液壓油,通常指礦物油2液壓升降舞臺(tái)結(jié)構(gòu)分析與設(shè)計(jì)2.1 升降舞臺(tái)簡介舞臺(tái)升降臺(tái)是劇場演出過程中使用的一種重要設(shè)備,它主要用于載人或載景升降,要求運(yùn)行平穩(wěn)、噪聲低、安全可靠。其臺(tái)面尺寸一般為16m2m,升降行程一般為 7.53.5m,升降速度為0.2m/s,承載能力應(yīng)能滿足劇場要求:靜載荷400kg/,動(dòng)載荷200kg/。目前,國內(nèi)外普遍采用的是滑動(dòng)螺母絲杠升降臺(tái)。普通滑動(dòng)螺母絲杠副的特點(diǎn)是可以按需要設(shè)計(jì)成自鎖,這對(duì)載人升降臺(tái)是一很好的優(yōu)點(diǎn),或者說是必須。但它在設(shè)計(jì)成自鎖下機(jī)械效率很低,理論上可達(dá)到40%,實(shí)際證明,由于加工精度、表面粗糙度、潤滑條件、安裝條件的限制,真正能達(dá)到的機(jī)械效率只有20%30%。而舞臺(tái)升降臺(tái)的載重較重,一般為 10 t左右,加上升降速度較快,最高達(dá)0.2m/s,這樣勢必要求所選電動(dòng)機(jī)的功率較大,一般為20 KW以上,同時(shí),由于舞臺(tái)升降臺(tái)一般要求變頻調(diào)速,這樣所選用的變頻器的容量也就較大。功率(容量)增大,成本上升,尤其是變頻器,隨容量的增大,成本急劇上升。為此,我們將金屬切削機(jī)床上采用的滾柱螺母絲杠副用于舞臺(tái)升降臺(tái)的升降傳動(dòng)中。滾珠螺母絲杠副具有較高的傳動(dòng)效率,但它不能自鎖,這對(duì)載人升降臺(tái)不安全;而滾柱螺母絲杠副的傳動(dòng)效率高于普通滑動(dòng)螺母絲杠副,且它能自鎖,常用于垂直移動(dòng)的傳動(dòng),如平面磨床的磨頭。滾柱螺母絲杠副要求絲杠直徑較粗,否則,絲杠螺紋與滾柱的環(huán)槽有可能發(fā)生干涉。這一要求在舞臺(tái)升降臺(tái)上是完全能滿足的,因?yàn)橛缮敌谐趟鶝Q定的絲杠長度較長,一般為57 m ,根據(jù)剛度要求,絲杠直徑本身就要求較粗。2.2 升降舞臺(tái)投影圖圖21升降舞臺(tái)平面圖2.3液壓升降舞臺(tái)的方案的確定2.3.1升降舞臺(tái)液壓系統(tǒng)升降舞臺(tái)液壓系統(tǒng)是為劇場配套而設(shè)計(jì)制造的。其升降功能由4根液壓缸頂升叉架完成,4根液壓缸的同步由帶補(bǔ)正裝置的同步回路完成。升降臺(tái)是液壓系統(tǒng)的重要應(yīng)用領(lǐng)域,升降臺(tái)液壓系統(tǒng)也是比較成熟的技術(shù),但此套大型系統(tǒng)與常規(guī)的小型升降臺(tái)系統(tǒng)相比有其特殊性,不能簡單套用,必須解決好以下問題:(1)保證動(dòng)作平穩(wěn),舞臺(tái)上載重量變化很大,且液壓缸在升降過程中隨叉架角度變化較大,因此液壓缸負(fù)載變化較大,液壓系統(tǒng)必須要能克服負(fù)載變化對(duì)速度產(chǎn)生的影響,確保機(jī)構(gòu)無沖擊地平穩(wěn)運(yùn)行;(2)根據(jù)舞臺(tái)承受的動(dòng)靜載荷、速度要求,經(jīng)過計(jì)算,得出上升過程中液壓缸無桿腔工作壓力約為13 MPa,單根液壓缸理論流量為32.739.5L/min; (3)下降過程主要靠自重,但必須加以控制,尤其是如此大型的設(shè)備,一旦失控極其危險(xiǎn)。2.3.2 常用升降機(jī)構(gòu)比較 (1)液壓升降臺(tái) 采用液壓技術(shù),升降平穩(wěn)、噪音低。 (2)垂直絲杠升降臺(tái) 采用絲杠傳動(dòng)方式,實(shí)現(xiàn)雙層臺(tái)面的升降。根據(jù)需要可多塊組成升降臺(tái)群,能在行程范圍內(nèi)組成不同的臺(tái)階,滿足會(huì)議和演出的需要,是在舞臺(tái)上搭設(shè)亭、臺(tái)、樓、閣的理想道具。 (3)水平絲杠升降臺(tái) 該結(jié)構(gòu)的升降臺(tái)具有土建量小、所需基坑淺、行程大,運(yùn)行平穩(wěn),噪音低定位準(zhǔn)確、造價(jià)低等優(yōu)點(diǎn)。采用水平絲杠傳動(dòng),通過剪叉結(jié)構(gòu)實(shí)現(xiàn)臺(tái)面的升降運(yùn)動(dòng),在行程范圍內(nèi)可任意停止。(4)鏈條式升降臺(tái)有良好的導(dǎo)向機(jī)構(gòu),保證設(shè)備運(yùn)行時(shí)無傾斜。 (5)齒輪齒條式升降臺(tái)傳動(dòng)精確,造價(jià)高。 (6)螺旋器升降臺(tái)具有普通升降臺(tái)的全部功能,主要特點(diǎn)是設(shè)備占用基坑小,行程大。設(shè)備高度僅200一500 mm行程可達(dá)14 m。當(dāng)舞臺(tái)建在2層以上的建筑物時(shí)因空間受到限制時(shí)尤為適合。2.3.3 升降臺(tái)機(jī)構(gòu)形式 如圖1所示,采用剪叉結(jié)構(gòu)達(dá)到放大行程的效果,而且要求基坑較淺,從而可節(jié)約投資。液壓缸左右對(duì)稱布置,工作時(shí)總體水平方向所受合力為零;使得臺(tái)面水平方向不發(fā)生運(yùn)動(dòng),只是垂直方向的往復(fù)運(yùn)動(dòng)。上下方向設(shè)置有高低位行程開關(guān),可保證升降高度。2.3.4 臺(tái)面結(jié)構(gòu) 如圖2所示,該臺(tái)面采用析架機(jī)構(gòu)可滿足整體剛度的要求,保證人踩上去不會(huì)產(chǎn)生晃動(dòng)和腳底不實(shí)的感覺。當(dāng)臺(tái)面比較窄時(shí),可并列設(shè)置2組彬架;當(dāng)臺(tái)面比較寬的時(shí)候,要采用多個(gè)并列;一般情況下間距為400一500 mm?;谝陨戏治觯驹O(shè)計(jì)主要是對(duì)舞臺(tái)升降技術(shù)中的1種形式的液壓升降臺(tái)進(jìn)行設(shè)計(jì)。3單層升降舞臺(tái)液壓系統(tǒng)的設(shè)計(jì)計(jì)算(左側(cè))3.1單層升降舞臺(tái)水平運(yùn)動(dòng)部分設(shè)計(jì)3.1.1 確定液壓系統(tǒng)的工作要求總體要求:(1)要求單層升降臺(tái)的伸出與縮回采用“快進(jìn)慢速接近快退”的動(dòng)作循環(huán)。(2)嚴(yán)格保證多缸的動(dòng)作同步。(3)在單層和三層的下降回路中應(yīng)保持平衡,使下降平穩(wěn)。(4)各動(dòng)作順序有相應(yīng)的互鎖關(guān)系,以保證 根據(jù)升降舞臺(tái)的動(dòng)作順序確定該系統(tǒng)的工作循環(huán)為:快速前進(jìn)工作進(jìn)給快速退回原位停止。根據(jù)具體工作要求計(jì)算得出,快速進(jìn)退時(shí)的速度約為4500mm/min(0.075m/s)。工作時(shí)的進(jìn)給速度應(yīng)為20120mm/min(0.00030.02m/s)范圍內(nèi)作無極調(diào)速運(yùn)動(dòng)部件的行程為4000mm,其中工作行程為3050mm。運(yùn)動(dòng)部件的自身重力為0.6t,啟動(dòng)換向時(shí)間為=0.05s,采用水平放置的平行導(dǎo)軌靜摩擦系數(shù)=0.2,動(dòng)摩擦系數(shù)為=0.1。3.1.2 分析液壓系統(tǒng)的工況 計(jì)算液壓缸在工作行程各階段的負(fù)載 啟動(dòng)加速階段: (+)/ N 工進(jìn)階段: N 快進(jìn)或快退階段: 653.3N 將液壓缸在各階段的速度與負(fù)載值列于表一中表32 液壓缸在各階段的速度與負(fù)載階 段速度v/(m/s)負(fù)載F/N啟 動(dòng) 加 速0.0752306.67工 進(jìn)0.00030.0026553.3快 進(jìn) 快 退0.0756553.33.2單層升降舞臺(tái)垂直部分的設(shè)計(jì)3.2.1確定液壓系統(tǒng)的工作要求 根據(jù)工作要求,確定該系統(tǒng)的工作循環(huán)為工進(jìn)工退原位停止。根據(jù)具體加工要求就計(jì)算得出:工作進(jìn)給時(shí)的速度應(yīng)在20120mm/min(0.00030.002m/s)范圍內(nèi)作無極調(diào)速,運(yùn)動(dòng)部件的最大行程為3m,其中工作行程為2m。運(yùn)動(dòng)部件的自身重為0.6t,啟動(dòng)換向時(shí)間為t=0.05t=0.05。系統(tǒng)豎直放置的垂直導(dǎo)軌的靜摩擦系數(shù)=0.2,動(dòng)摩擦系數(shù)為=0.1。3.2.2 分析液壓系統(tǒng)的工況工進(jìn)階段: F=6553.3N工退階段: F=6553.3N表3-3 液壓系統(tǒng)在各階段的速度和負(fù)載階段速度v/(m/s)負(fù)載F/N工進(jìn)0.00030.0026553.3工退0.00030.0026553.33.3確定液壓缸的主要參數(shù)1.初選液壓缸的工作壓力 根據(jù)計(jì)算得出各階段負(fù)載值的最大值,曲液壓缸的工作壓力為0.3MPa。2.確定液壓缸的主要結(jié)構(gòu)參數(shù)最大負(fù)載啟動(dòng)加速階段負(fù)載:N,求得 m 根據(jù)液壓缸內(nèi)徑系列將所計(jì)算的值圓整為標(biāo)準(zhǔn)值,取mm。 為實(shí)現(xiàn)快進(jìn)與快退速度相同,采用差動(dòng)連接。則,所以 mm 查得,符合活塞桿標(biāo)準(zhǔn)直徑系列,由mm, mm。算出液壓缸無桿腔有效工作面積為cm2,有桿腔有效工作面積為 工作進(jìn)給采用調(diào)速閥調(diào)速,調(diào)速閥最小穩(wěn)定流量,工進(jìn)速度則 +=+0.004 =Pa=24.35MPa 單向順序閥調(diào)節(jié)壓力為:P-=-4000=0.75Pa=0.75MPa 3.6.2 系統(tǒng)發(fā)熱及溫升計(jì)算1)發(fā)熱量估算 從整個(gè)工作循環(huán)看,功率變化較大,計(jì)算平均發(fā)熱量。從速度循環(huán)圖可近似計(jì)算各階段的時(shí)間:快速下降 =7.85s;慢速折彎啟動(dòng)時(shí)初壓 =1.25s 終壓 =0.83s快速退回 =3.77s循環(huán)周期 T=+ =7.85+1.25+0.83+3.77 =13.7s從功率循環(huán)圖可求出各階段液壓缸的輸出功率。但應(yīng)扣除液壓缸的機(jī)械效率因素的影響,因功率循環(huán)圖是液壓缸的輸入功率的變化規(guī)律??焖傧陆?0慢速,初壓 =0.3kW 終壓 該段較復(fù)雜,可從速度,負(fù)載循環(huán)圖來求均值: =Fv=(1000000+510000)(0.0120)22 =3150w=3.15kw快速退回0.87=0.870.91=0.79kW從壓力,流量循環(huán)圖求各階段液壓泵輸入流量??焖傧陆担?1.162=68.2L/min=1137cm2/s =+=0+0.142=0.14MPa(近似用快退工況壓力損失數(shù)據(jù)) =187W慢速折彎,初壓=1.132.5=35.75L/min=596cm2/s =0.61+0.04=0.65MPa =456W 終壓=17.88L/min=298cm2/s =12.76+0.03=12.8MPa =4488W快速退回:=0.83+0.142=0.97MPa =1.162.9=62.19L/min=1153cm2/s =1316W系統(tǒng)的發(fā)熱量為:H=(-)+(-)+(-)+(-)/T =(0.187-0)7.85+(0.456-0.3)1.25+(4.488-3.15)0.83+(1.316-0.79)3.77 /13.7 =0.347kW2)系統(tǒng)熱平衡溫度計(jì)算 設(shè)油箱邊長比為1:1:11:2:3范圍,油箱散熱面積為 A=0.065V=0.065378=3.4m2 假定自然通風(fēng)不好,取油箱散熱系數(shù)為 =0.008Kw/m2 室內(nèi)環(huán)境溫度為30攝氏度,系統(tǒng)熱平衡溫度為=+ =30+=43滿足t=50,油箱容量合適。4升降舞臺(tái)三層液壓系統(tǒng)的設(shè)計(jì)計(jì)算4.1確定液壓系統(tǒng)的工作要求根據(jù)工作要求,確定該系統(tǒng)的工作循環(huán)為工進(jìn)工退原位停止。根據(jù)具體加工要求就計(jì)算得出:工作進(jìn)給時(shí)的速度應(yīng)在20120mm/min(0.00030.002m/s)范圍內(nèi)作無極調(diào)速,運(yùn)動(dòng)部件的最大行程為3m,其中工作行程為2m。運(yùn)動(dòng)部件的自重為0.6t,啟動(dòng)換向時(shí)間為=0.05=0.05。系統(tǒng)豎直放置的垂直導(dǎo)軌的靜摩擦系數(shù)=0.2,動(dòng)摩擦系數(shù)為=0.1。4.2 分析液壓系統(tǒng)的工況工進(jìn)階段: F=6553.3N工退階段: F=6553.3N表4-1 液壓系統(tǒng)在各階段的速度和負(fù)載階段速度v/(m/s)負(fù)載F/N工進(jìn)0.00030.0026553.3工退0.00030.0026553.34.3確定液壓缸的主要參數(shù)1.初選液壓缸的工作壓力根據(jù)計(jì)算得出各階段負(fù)載值的最大值,并參照同類升降舞臺(tái)取液壓缸工作壓力為0.7MPa。2.確定液壓缸的主要結(jié)構(gòu)參數(shù) 最大負(fù)載為工進(jìn)階段負(fù)載F=6553.3N,求得 D=0.11m=110mm 根據(jù)液壓缸內(nèi)徑系列將所計(jì)算的值圓整為標(biāo)準(zhǔn)值,取D=110mm。 為規(guī)定工進(jìn)與工退速度相同采用差動(dòng)連接,則d=0.7D,所以 d=0.7110=77mm 根據(jù)液壓缸內(nèi)徑系列將所計(jì)算的值圓整為標(biāo)準(zhǔn)值。取d=80mm。由D=110mm d=80mm算出液壓缸無桿腔有效工作面積為=50.24cm2工作進(jìn)給采用調(diào)速閥調(diào)速,查產(chǎn)品樣本調(diào)速閥的最小穩(wěn)定流量=0.05L/min 工進(jìn)速度=20mm/min ,則 =25cm2+ + =3.75+0.5+0.5+0.5 =4.75MPa 3)快退 進(jìn)油路壓力總損失為: =0.2+0.5=0.082MPa 回油路總壓力損失為: =0.2+0.5+0.2=0.592MPa則快退階段,液壓泵的工作壓力Pp為=+=(1.5+0.082)=1.582MPa2 溫升驗(yàn)算以工進(jìn)時(shí)的消耗功率計(jì)算溫升。工進(jìn)時(shí),液壓缸的有效功率為: =0.0278kW發(fā)熱功率為:=0.556-0.0278=0.529kW油箱散熱面積 A=6.5V=2.85m2 溫升:=22.8 式中,取散熱系數(shù)。溫升在允許的范圍內(nèi),可不設(shè)冷卻裝置。升降舞臺(tái)總體液壓系統(tǒng)原理圖5液壓系統(tǒng)的設(shè)計(jì)與分析 擬定液壓系統(tǒng)原理圖是整個(gè)液壓系統(tǒng)設(shè)計(jì)中最重要的一環(huán)節(jié),它的好壞從根本上影響整個(gè)液壓系統(tǒng)。因此本次設(shè)計(jì)中對(duì)有些回路考慮了多個(gè)方案并進(jìn)行了分析比較。5.1液壓回路的選擇5.1.1 確定供油方式根據(jù)前幾節(jié)的工況分析,在本設(shè)計(jì)中選用限壓式變量葉片泵和蓄能器聯(lián)合供油的方式,蓄能器在系統(tǒng)中作為應(yīng)急能源,限壓式變量葉片泵可根據(jù)系統(tǒng)的負(fù)載變化自動(dòng)調(diào)節(jié)輸出流量具有降低能源消耗、限制油液溫升的特點(diǎn),還具有自吸能力好、輸出壓力脈動(dòng)小、對(duì)污染敏感度小、噪聲低,但粘度對(duì)效率的影響較大結(jié)構(gòu)復(fù)雜、功率損失大、價(jià)格較貴。5.1.2 確定調(diào)速方法調(diào)速方法有節(jié)流調(diào)速、容積調(diào)速和聯(lián)合調(diào)速。在本設(shè)計(jì)中選用選用限壓式變量葉片泵和調(diào)速閥組成的容積節(jié)流調(diào)速回路,容積節(jié)流調(diào)速回路由變量泵供油,用流量閥改變進(jìn)入液壓缸的流量,以實(shí)現(xiàn)工作速度的調(diào)節(jié),這時(shí)泵的供油量自動(dòng)與液壓缸所需的流量相所適應(yīng)。這種回路的特點(diǎn)是效率高、發(fā)熱小(比節(jié)流調(diào)速)速度穩(wěn)定性(比容積調(diào)速回路)好。常用于調(diào)速范圍大的中、小功率場合。5.1.3速度換接回路的選擇速度換接回路的形式常用行程閥或電磁閥來實(shí)現(xiàn)。行程閥具有換接平穩(wěn)、工作可靠、換接位置精度高,電磁閥具有結(jié)構(gòu)簡單、控制靈活、調(diào)整方便。在本設(shè)計(jì)中的快進(jìn)回路與慢速接近回路的換接是采用了由行程開關(guān)控制的電磁換向閥,具有換接位置精度高、換接靈活的優(yōu)點(diǎn)。5.1.4換向回路的選擇根據(jù)執(zhí)行元件對(duì)換向性能的要求選擇換向閥機(jī)能和控制方式。在本設(shè)計(jì)中多采用電磁換向閥實(shí)現(xiàn)回路的換向,它具有操作方便、便于布置、低速換向的特點(diǎn),在泵的卸荷回路中采用了手動(dòng)換向閥。5.1.5壓力控制回路的選擇本設(shè)計(jì)中采用了容積節(jié)流調(diào)速,常用溢流閥組成限壓、安全、保護(hù)回路。5.1.6其他回路的分析與選擇根據(jù)升降舞臺(tái)的要求,本設(shè)計(jì)中選用了多缸同步回路、順序動(dòng)作回路、平衡回路、瑣緊回路和卸荷回路等。在選擇中對(duì)同步回路和順序動(dòng)作回路做了詳細(xì)的分析。(1)多缸同步回路: 同步回路是保持兩個(gè)或兩個(gè)以上的液壓缸在運(yùn)動(dòng)中保持相同的位移或相同的速度,常用的有:(a)帶補(bǔ)償措施的串聯(lián)液壓缸同步回路;(b)調(diào)速閥控制的同步回路,;(c)機(jī)械連接同步回路,。(a)帶補(bǔ)償措施的串聯(lián)液壓缸同步回路在這個(gè)回路中液壓缸1的有桿腔面積與液壓缸2的無桿腔面積相等便可以實(shí)現(xiàn)兩液壓缸的升降同步。為了保證嚴(yán)格同步,采用取補(bǔ)償措施以避免誤差的累積,在每一次下行運(yùn)動(dòng)中能消除同步誤差。其原理為:當(dāng)換向閥1左位工作時(shí),兩缸下行,若缸2的活塞先運(yùn)動(dòng)到底,它就觸動(dòng)行程開關(guān)a使電磁鐵3YA通電,壓力油經(jīng)閥2的左位向缸一的有桿腔補(bǔ)油,推動(dòng)活塞繼續(xù)運(yùn)動(dòng)到底,誤差即被消除;若缸一先運(yùn)動(dòng)到底則觸動(dòng)行程開關(guān)b使電磁鐵4YA通電,壓力油經(jīng)閥二的右位,控制壓力油使液控單向閥3打開,缸2無桿腔的油液經(jīng)液控單向閥3和閥2回油箱,使活塞繼續(xù)運(yùn)行到底。這種串聯(lián)式的同步回路只適用于負(fù)載較小的液壓系統(tǒng),能保證嚴(yán)格同的步。(b) 調(diào)速閥控制的同步回路 在這個(gè)回路中,兩個(gè)調(diào)速閥分別調(diào)節(jié)兩液壓缸活塞的運(yùn)動(dòng)速度,仔細(xì)調(diào)整兩個(gè)調(diào)速閥的開口可使兩液壓缸在同一個(gè)方向上實(shí)現(xiàn)速度同步。這種同步回路的結(jié)構(gòu)簡單并且速度可調(diào),但是由于油溫變化及調(diào)速閥性能差異等影響,顯然這種回路不易保證位置同步,且調(diào)整麻煩,速度同步精度也比較低,一般在5%7%左右。(c) 機(jī)械連接同步回路 其特點(diǎn)是:回路結(jié)構(gòu)簡單、工作可靠,但只適用于兩缸載荷相差不大的場合,連接應(yīng)具有良好的導(dǎo)向結(jié)構(gòu)和剛性,否則,回出現(xiàn)卡死現(xiàn)象。根據(jù)以上分析,在本設(shè)計(jì)中對(duì)同步精度要求較高,所以選用a方案。(2) 順序動(dòng)作回路:常用的順序動(dòng)作回路可分為壓力控制、行程控制和時(shí)間控制三類,其中前兩類應(yīng)用的較多。(a)壓力控制的順序動(dòng)作回路:壓力控制就是利用液壓系統(tǒng)工作過程中的壓力變化來使執(zhí)行件按順序先后動(dòng)作,這是液壓獨(dú)具的控制特性。壓力控制的順序動(dòng)作回路一般用順序閥或壓力繼電器來實(shí)現(xiàn)。在本設(shè)計(jì)中采用的順序閥控制的順序動(dòng)作回路,其優(yōu)點(diǎn)在于動(dòng)作靈敏安裝連接方便。(b) 用行程控制的順序動(dòng)作回路行程控制就是利用執(zhí)行元件運(yùn)動(dòng)到一定位置時(shí)發(fā)出控制信號(hào),使下一個(gè)執(zhí)行元件開始動(dòng)作。行程控制可利用行程閥和行程開關(guān)來實(shí)現(xiàn)。利用行程閥實(shí)現(xiàn)的順序動(dòng)作回路可靠,但動(dòng)作順序一旦確定再改變就困難,且管道長、布置麻煩。5.1.7 舞臺(tái)升降液壓系統(tǒng)工作原理該系統(tǒng)采用變量葉片泵和蓄能器聯(lián)合供油的方式,液壓泵為限壓式變量葉片泵,最高工作壓力為6.3。溢流閥4作安全閥用,其調(diào)整壓力為7。手動(dòng)換向閥5用于卸荷,過濾器6的過濾精度為10,用于回油過濾,當(dāng)回油壓力超過0.3時(shí)系統(tǒng)報(bào)警,此時(shí)應(yīng)更換過濾器的濾芯。5.1.8液壓系統(tǒng)組成及工作原理舞臺(tái)升降:油泵電機(jī)啟動(dòng)后,雙聯(lián)油泵1開始工作,但大流量泵和小流量泵均處于卸荷狀態(tài)。舞臺(tái)上升時(shí),電磁鐵YA6得電,升降回路升壓,大流量泵輸出的液壓油分別通過換向閥48再經(jīng)四個(gè)液控單向閥1215進(jìn)入四個(gè)液壓缸無桿腔,產(chǎn)生推力,克服舞臺(tái)重量和導(dǎo)軌副摩擦推動(dòng)舞臺(tái)上升。因液壓缸尺寸較大,舞臺(tái)上升速度較慢(設(shè)計(jì)上升速度為0.02m/s),為減少液壓元件的數(shù)量,保障系統(tǒng)的可靠性,不設(shè)置調(diào)速元件而采取由油泵和液壓缸尺寸予以直接保證的設(shè)計(jì)方案;當(dāng)舞臺(tái)停止上升或到達(dá)最大行程時(shí),電磁鐵YA6失電,換向閥25處于左位,主回路卸壓。由于液控單向閥1215鎖死,舞臺(tái)停止在鎖死位置;舞臺(tái)下降時(shí),電磁鐵YA5、YA6得電,系統(tǒng)控制回路升壓,高壓油進(jìn)入液控單向閥1215的先導(dǎo)控制閥,將液控單向閥打開,同時(shí)YA1YA4得電,換向閥47接油箱,舞臺(tái)依靠自重下降。下降速度可由調(diào)速閥1215調(diào)定。同步控制:本系統(tǒng)四條同步支路所選用的元件型號(hào)相同、各支路輸入流量相同,可以較好的保證四個(gè)伸縮式油缸的同步上升、同步下降。 平衡控制:為使四個(gè)液壓缸產(chǎn)生相同的推力,系統(tǒng)中采用四個(gè)單向閥1619將四條支路隔離開,然后用一個(gè)溢流閥20進(jìn)行壓力控制,保證各支路設(shè)定壓力相同。 舞臺(tái)伸縮:考慮到施工現(xiàn)場場地有限,為節(jié)約空間,提高效率,本設(shè)計(jì)中采用了雙聯(lián)式油泵。大流量泵用于驅(qū)動(dòng)舞臺(tái)升降,小流量泵用于驅(qū)動(dòng)液壓馬達(dá)帶動(dòng)舞臺(tái)伸縮。兩種運(yùn)動(dòng)可以獨(dú)立控制,互不干涉。油泵啟動(dòng)時(shí),通過換向閥27卸壓;需要控制舞臺(tái)外伸時(shí),電磁鐵YA9、YA7得電,換向閥24處于左位。高壓油經(jīng)閥24進(jìn)入液壓馬達(dá)驅(qū)動(dòng)其伸縮,通過馬達(dá)輸出軸齒輪與齒圈傳遞舞臺(tái)以驅(qū)動(dòng)力矩。若YA9、YA7得電,則馬達(dá)驅(qū)動(dòng)舞臺(tái)反轉(zhuǎn)。單向閥22、23和溢流閥26組成液壓馬達(dá)過載保護(hù)回路。5.2 液壓元件的選擇5.2.1 液壓泵的選擇根據(jù)前三節(jié)對(duì)液壓系統(tǒng)的工況分析來確定泵的最高工作壓力和最大供油量:(1)液壓泵的最高工作壓力: =(3.60.6)=4.2(2)液壓泵的最大供油量: 取K=1.1 則:=1.1=1.139.1=43查液壓元件產(chǎn)品樣本手冊(cè),選用YBX-40B型限壓式變量葉片泵,其技術(shù)參數(shù)為: 驅(qū)動(dòng)功率:P=9.8 KW(3)確定電動(dòng)機(jī)功率: 限壓式變量葉片泵的驅(qū)動(dòng)功率可按流量特性曲線拐點(diǎn)處的流量、壓力值計(jì)算。一般情況下可取 :=0.8,。則:式中:液壓泵的總效率,查表取=0.7 液壓泵的最大工作壓力() 液壓泵的額定流量() 所以:=4.7 (KW)查手冊(cè)選擇Y系列三相異步電動(dòng)機(jī),Y132M4型,額定功率=7.5 KW同步轉(zhuǎn)速。5.2.2 液壓閥的選擇 根據(jù)液壓系統(tǒng)原理圖計(jì)算液壓閥在不同工況時(shí)的工作壓力和最大實(shí)際流量,將計(jì)算值填入表51、52、53中,最后確定液壓閥規(guī)格。表51液壓元件明細(xì)表(單層舞臺(tái)的伸縮回路)序號(hào)名 稱型 號(hào)規(guī) 格實(shí)際流量/ L快進(jìn)慢速接近快退1限壓式變量葉片泵YBX-40B6.391.416.50.20.3162單向閥AF2-Fa10B6.3100 0.216.50.23.2163單向節(jié)流閥MK10G126.3504溢流閥YF3-10L4635手動(dòng)換向閥22S-H10B31.51006過濾器RS60100A10CF1 0.27手動(dòng)換向閥22S-H10B31.51008三位四通電磁換向閥34DF3O16B-A6.380 0.216.50.23.2169三位四通電磁換向閥34DF3M16B-A6.325 0.216.50.23.21610單向調(diào)速閥QA-F10D-U6.340 0.216.50.23.21611兩位三通電磁換向閥23DF3-6B2A6.325 0.216.50.23.21612三位四通電磁換向閥34DF3O6B-A6.325 0.213液控單向閥YAF3-a10B6.340 0.214壓力繼電器ST-02-B-200.77表52液壓元件明細(xì)表(單層舞臺(tái)的升降回路)序號(hào)名 稱型 號(hào)規(guī) 格實(shí)際流量/ L上 升下 降15三位四通電磁換向閥34DF3M10B-A6.340 0.2 25 18.816單向順序閥(作背壓)AXF3-10B0.56.363背壓時(shí) 0.3 25 18.817三位四通電磁換向閥34DF3O6B-A6.325 0.218液控單向閥YAF3-a10B6.340 0.219調(diào)速閥Q-8H6.3252.5 0.3 25 18.820三位四通電磁換向閥34DF3O6B-A6.325 0.221液控單向閥YAF3-a10B6.340 0.222三位四通電磁換向閥34DF3O6B-A6.325 0.223液控單向閥YAF3-a10B6.340 0.224壓力繼電器ST-02-B-200.77表53液壓元件明細(xì)表(三層舞臺(tái)的升降回路)序號(hào)名 稱型 號(hào)規(guī) 格實(shí)際流量/ L上 升下 降25三位四通電磁換向閥34DF3O16B-A6.3100 0.2 80 7026單向順序閥(作背壓)AXF3-10B0.56.363背壓時(shí) 0.3 39 3127、31、33、57、42、40、三位四通電磁換向閥34DF3O6B-A6.325 0.228、32、34、38、43、41液控單向閥YAF3-a10B6.340 0.230、44調(diào)速閥Q-H206.310010 0.3 39 3135、47、48、45壓力繼電器ST-02-B-200.7736單向順序閥AXF3-10B0.56.363進(jìn)油時(shí) 0.2 39 3139單向順序閥(作背壓)AXF3-10B0.56.363背壓時(shí) 0.2 39 315.2.3蓄能器的選擇 根據(jù)蓄能器在液壓系統(tǒng)中的功用,確定其類型和主要參數(shù)。(1)在本設(shè)計(jì)中蓄能器用來作應(yīng)急能源,其有效工作容積為: = 式中:液壓缸有效工作面積() 液壓缸的行程()=1.17 油液損失系數(shù),一般取=1.2(2)氣囊式蓄能器總?cè)莘e的()的計(jì)算: 按等溫過程計(jì)算: 式中:充氣壓力(絕對(duì)壓力) () 最低工作壓力, 最高工作壓力, 有效工作容積查產(chǎn)品樣本手冊(cè),選用NXQ1-63/10型,公稱容積63 L,公稱壓力。5.2.4其它輔助元件的確定(1)油管:取 式中: 管道中最大流量,查手冊(cè),根據(jù)GB/T3683-1992,采用1 型公稱直徑為的一層鋼絲編織的液壓橡膠軟管。(2)過濾器:吸油過濾器:查產(chǎn)品樣本手冊(cè)采用10080型,額定壓力為:1.6,流量:100L/min,過濾精度8河南理工大學(xué)畢業(yè)設(shè)計(jì)說明書摘 要本次畢業(yè)設(shè)計(jì)是關(guān)于液壓升降舞臺(tái)的設(shè)計(jì)。首先對(duì)液壓升降舞臺(tái)作了簡單的概述;接著分析了液壓升降舞臺(tái)的選型原則及計(jì)算方法;然后根據(jù)這些設(shè)計(jì)準(zhǔn)則與計(jì)算選型方法按照給定參數(shù)要求進(jìn)行選型設(shè)計(jì);接著對(duì)所選擇的液壓升降舞臺(tái)各主要零部件進(jìn)行了校核。最后簡單的說明了液壓升降舞臺(tái)的安裝與維護(hù)。目前,液壓升降舞臺(tái)正朝著長距離,高速度,低摩擦的方向發(fā)展,近年來出現(xiàn)的液壓升降舞臺(tái)就是其中的一個(gè)。在液壓升降舞臺(tái)的設(shè)計(jì)、制造以及應(yīng)用方面,目前我國與國外先進(jìn)水平相比仍有較大差距,國內(nèi)在設(shè)計(jì)制造液壓升降舞臺(tái)過程中存在著很多不足。AbstractThe design is a graduation project about the hydraulic pressure lift proscenium. At first, it is introduction about hydraulic pressure lift proscenium. Next, it is the principles about choose component parts of hydraulic pressure lift proscenium. After that t hydraulic pressure lift proscenium abase on the principle is designed. Then, it is checking computations about main component parts of hydraulic pressure lift proscenium. At last, it is explanation about fix and safeguard of hydraulic pressure lift proscenium. Today, long distance, high speed, low friction is the direction of hydraulic pressure lift prosceniums development. Hydraulic pressure lift proscenium is one of them. At present, we still fall far short of abroad advanced technology in design, manufacture and using. There are a lot of wastes in the design of hydraulic pressure lift proscenium。1Grindiability comparison between conventional and nanostructured material coatings.Bi Zhang, Xianbing Liu, Zhaohui Deng and Jian MengDepartment of Mechanical Engineering, University of Connecticut, Storrs, CT 06269, USAEmail: zhangengr.uconn.eduABSTRACT This paper compares the grindability of conventionaland nanostructured material coatings in terms ofnormal grinding force, specific grinding energy, surfacefinish and surface topography. Material removalmechanism is correlated with the microstructures of thematerials such as material grain size. The effect of thedecreasing material grain size in nanostructuredmaterials on the grindability is studied.1 INTRODUCTION In grinding of ceramics, the effects of grindingprocess parameters have been extensively studied (e.g.,Kirchner and Conway, 1985;Tnshoff and Brinksmeier,1988; Blake et al., 1988). It is of equal importance tostudy the influence of material microstructure. One ofthe material microstructures is the grain size, whichinfluences the mechanical properties, such as hardnessand toughness, and therefore the grindability ofceramics. Few works have been done on this aspect. Intheir work, Roth and Tnshoff (1993) studied thegrindability of alumina with different grain sizes increep feed grinding and conventional surface grinding.Both hardness and toughness for n-Al2O3/13TiO2 andn-WC/12Co coatings are found higher than theirconventional counterparts due to the reduced grain sizeand richer binder phases. Hardness of a material is itsability to resist plastic deformation. Plastic deformationis induced by the dislocation movement. The richer binder phases in nanostructured materials constrainmaterial flow and therefore plastic deformation. Unlike in the conventional materials, the increase of hardness in nanostructured materials does not lead to thedecrease of toughness due to more bridging ligaments,higher in-situ flow stress and higher rupture strength (Jia, et al., 1998). The difference in hardness and toughness between nanostructured and conventional materials can be expected to influence the grindability of their coatings. The large quantities of voids, cracks and microcracks induced by the thermal spray process greatly influence the properties of coatings made of these materials. The difference in hardness and toughness between conventional and nanostructured material coatings are not as much as in their bulk counterparts. Table 1 shows the typical properties of conventional and nanostructured WC/12Co and Al2O3/13TiO2 coatings. Normally, grindability is evaluated based on material removal rate, grinding force, surface finish and integrity of ground samples. In this paper, normal grinding force, specific grinding energy and surface finish are compared for nanostructured and conventional coatings. In addition, the scanning electronic microscopy (SEM) is used to assess the effects of grain sizes on the material removal mechanisms. Table 1 Typical Properties of the Conventional and Nanostructured WC/12Co and Al2O3/13TiO2 Coatings.c-WC/12Con-WC/12Coc-Al2O3/13TiO2n-Al2O3/13TiO2Bonding strength, MPa 82.7 89.6 15.5 20.7Powder grain size, mm 1.3 0.04 2.5 0.05Mass density, g/cm3 14.2 14.5 3.5-4.0 3.7-4.1Vickers hardness, GPa 12.00 12.50 10.44 10.57Toughness, MPa m1/2 16.0 16.5 3.3 3.52 EXPERIMENTAL CONFIGURATION2.1 Sample preparation and characterization Conventional and nanostructured material coatings were made on low carbon steel substrates of dimensions of 25 75 4 mm3 that were cleaned and blasted before thermal spray. The conventional and nanostructured WC/12Co coatings were produced using the high velocity oxygen fuel method, and the conventional and nanostructured Al2O3/13TiO2 coatings were prepared by the plasma thermal spray method. All the coatings had a thickness of around 0.5mm. The coated samples were cut into 25 4 4 mm3 for grinding. Fig.1 shows the SEM observations of c/n-WC/12Co coatings. Fig.1 (b) indicates that the smaller grains of WC are bonded together by the binder material cobalt and a large quantity of porosities can be observed in both conventional and nanostructured WC/12Co coatings. There are no obvious cracks found in conventional and nanostructured WC/12Co coatings. Fig.2 shows the typical surface features of the thermally sprayed conventional and nanostructured Al2O3/13TiO2 coatings: pores, cracks, microcracks and segmented structures formed by the connected microcracks perpendicular to the coating surface. Priorto the formal grinding test, the coatings were preground 2 with a diamond wheel of a mean grit size of 15 mm under minimum loading to avoid damaging the coatings. This preparation process was effective in getting rid of the random influence from the thermal spray process and making the samples more uniform, although it was time-consuming and effortsdemanding.2.2 Grinding experiments Grinding experiments were conducted on a precision grinding machine (Dover Model 956-S) with the computer numerical control (CNC). The machine had aerostatic bearings for its spindle and x, y, z slideways. The spindle had an axial run-out of 0.05 mm and the three slideways had a straightness error of 0.1 mm/25mm. A laser interferometer was equipped to the machine that formed feedback loops for the x, y, z slideways with a resolution of 0.07 mm. The loop stiffness of the machine was measured to be 50 N/mm. In this study, a diamond grinding wheel SD600N100V (600V) was used to grind the coatings under different conditions, and the ground samples were compared. The wheel speed was set to 33 m/s or 3500 rpm. In order to investigate the effect of material removal rate (MRR) on residual stresses, depths of cut were set at 2, 5, 15 and 30 mm and feedrates at 1, 4, and 8 mm/s for the grinding experiments. Water-based synthetic solution (ITW fluid products Group, Rustlick G-10066D) was used as grinding coolant.2.3 Post-grinding evaluation A surface profilometer (Federal Products, Surfanalyzer 5000) was used to measure surface finish (Ra) of ground coatings along the directions perpendicular to the grinding direction. An SEM (JOEL, Model JSM 840) was used to observe the surfaces of the ground coatings. One issue in SEM observations was to differentiate grinding damage from the coating defects. A large quantity of defects such as voids, unmolten particles, cracks and microcracks were identified in the as-sprayed coatings (Fig.1 and Fig.2). Because some of these defects can be easily mistaken as grinding damage, SEM examinations of the assprayed coatings were conducted to identify the defects from the spray process. It can be found that the voids from the thermal spray process normally appeared with smooth edges. From Fig.1 and Fig.2 the cracks or microcracks on the as-sprayed coatings were connected to each other without obvious directionality. With the as-sprayed coatings as a reference, the grinding damage was identified.3 RESULTS AND DISCUSSIONS3.1 Comparison of normal grinding force The normal grinding forces are important in characterizing a grinding process. Fig.3 compares the normal grinding forces in grinding c/n-Al2O3/13TiO2 and c/n-WC/12Co coatings at the same grinding conditions. The normal grinding force is higher for n-Al2O3/13TiO2 than for its conventional counterpart. One can also observe that the break-in force for n-Al2O3/13TiO2 is larger. This shows that the resistance to wearing for n-Al2O3/13TiO2 is higher due to its enhanced mechanical properties such as hardness and toughness when compared to its conventional counterpart. A similar trend is observed in grinding c/n-WC/12Co coatings: higher grinding force and break-in force for nanostructured coatings. Fig.3 also shows that the difference between the grinding forces for the nanostructured and conventional coatings becomes smaller at a large wheel depth of cut. This means that the material grain size exerts stronger influence on the grinding force at a low material removal rate. When the wheel depth of cut or material removal rate increases, the influence of grain size becomes second to that of grinding process parameters.3.2 Comparison of tangential grinding force andspecific grinding energy Tangential grinding force is much smaller than normal grinding force due to large negative rake angles of abrasive grits in grinding. The grinding force ratio(a) c-WC/12Co (b) n-WC/12Co(a) c-Al2O3/13TiO2 (b) n-Al2O3/13TiO2Fig. 2 SEM observations of as-sprayed c/n-Al2O3/13TiO2 coatings. Fig. 1 SEM observations of as-sprayed c/n-WC/12Co coatings.222222000000 _mm 222222000000 _mm1200 _ _mm 1200 _ mm3 indicates the relative magnitude of the normal grinding force Fn to the tangential grinding force Ft and is defined astnFFl = (1) Fig.4 shows the grinding force ratio vs. wheel depth of cut for the four coatings. The grinding force ratio is higher for c/n-Al2O3/13TiO2 coatings than for c/n-WC/12Co coatings. c/n-Al2O3/13TiO2 coatings are more brittle than c/n-WC/12Co coatings. Under the same grinding conditions, brittle fracture is more obvious for c/n-Al2O3/13TiO2 coatings. The dominant ductile flow in grinding c/n-WC/12Co coatings results in a relatively high tangential grinding force and therefore a lower grinding force ratio. It is observed that the grinding force ratio of the n-Al2O3/13TiO2 coatings is distinctly different from that of the c-Al2O3/13TiO2 coatings while the difference for the grinding force ratios of n-WC/12Co and c-WC/12Co coatings is insignificant. The grinding force ratios for the four coatings decrease with the increase of material removal rate or wheel depth of cut. On the other hand, the grinding force ratios for the four coatings change over a relatively narrow range, which suggests that the material removal mechanism does not change much for the given range of the wheel depth of cut. The specific grinding energy U is defined as the energy required to remove a unit volume of material, which is derived from the tangential grinding force,ft cW d vF vU = (2) where vc the grinding speed; W the width of a workpiece; d the wheel depth of cut; vf is feedrate. Fig.5 presents the effect of grain size on the specific grinding energy and the change of specific grinding energy with wheel depth of cut. The specific grinding (a) Conventional and nanostructured Al2O3/13TiO2. (b) Conventional and nanostructured WC/12Co. Fig. 3 Comparison of normal grinding force in grinding conventional and nanostructured coatings.0 10 20 3002468Depth of cut, mmNormal grinding force, N/mm2Nano.Conv.Wheel speed: 33 m/sFeedrate: 4 mm/sWheel: 600V0 10 20 3002468Depth of cut, mmNormal grinding force, N/mm2Nano.Conv.Wheel speed: 33 m/sFeedrate: 4 mm/sWheel: 600VFig. 4 Comparison of grinding force ratio.00 10 20 3036912Depth of cut, mmGrinding force ratio, ln-WC/12Coc-WC/12Con-Al2O3/13TiO2c-Al2O3/13TiO2Wheel speed: 33 m/sFeedrate: 4 mm/sWheel: 600V Fig. 5 Comparison of specific grinding energy.0 10 20 300.00.51.01.52.02.5Depth of cut, mmSpecific grinding energy, 103 J/mm3n-WC/12Coc-WC/12Con-Al2O3/13TiO2c-Al2O3/13TiO2Wheel speed: 33 m/sFeedrate: 4 mm/sWheel: 600V4 Energy for four coatings decreases with the wheel depth of cut and asymptotically reaches a limit. The high value of specific grinding energy at small depth of cut suggests that only a part of the energy is associated with the chip formation (Malkin, 1989). Generally, the specific grinding energy consists of chip-forming energy Uch, sliding energy Upl and plowing energy Usl, ch pl sl U =U +U +U (3) Except Uch, the rest of the specific grinding energy is attributed to sliding and plowing between the workpiece and abrasive grits at a small depth of cut. At a larger depth of cut, sliding becomes insignificant and chip formation commen. However, plowing still exists, which reflects by the grinding marks and material pile-up on the ground surface. Only Uch is actually used in removing material and forming new surface. Theoretically, the asymptotical limit in Fig.5 is Uch. Relative flat curves for c/n-Al2O3/13TiO2 coatings in Fig.5 suggest that the energy expended in plowing is not dominant due to their high brittleness. The reduced grain size in nanostructured coatings apparently increases the specific grinding energy. More energy is needed for plowing due to enhanced hardness in nanostructured material coatings. The higher toughness also means more energy required for new surfaceformation in grinding.3.3 Comparison of surface roughness Surface roughness was measured to characterize the ground coatings. Fig.6 shows that the influence of grain size on surface roughness of both ground coatings is significant. Opposite to the grinding force and specific grinding energy, the reduced grain size results in the decrease of the surface roughness for both nanostructured coatings, which can be explained by material removal mechanism. As observed in SEM photos (Fig.7 and Fig.8), brittle fracture dominates in grinding c-Al2O3/13TiO2 coatings while ductile flow plays a main role in grinding n-Al2O3/13TiO2 coatings. Although ductile flow is the major material removal mechanism in grinding both c/n-WC/12Co coatings, the observed transgranular fracture may partially contribute to surface roughness in c-WC/12Co coatings.Similar to the grinding force, surface roughness for ground conventional and nanostructured coatings are closer to each other at a larger wheel depth of cut, which means that the effect of reduced grain size in nanostructured coatings disappears at a higher material removal rate.3.4 SEM surface observations and comparison Fig.7 shows the SEM observations of ground c/n-WC/12Co coatings under the same grinding conditions. The ground c-WC/12Co coating surface is more segmented and larger WC grains can be observed when compared to the ground n-WC/12Co coating surface. The ground n-WC/12Co coating surface is completely covered with a layer of plastically deformed material and the WC grain boundary is hardly observable. The comparison of the SEM surface observations of ground c/n-Al2O3/13TiO2 coatings is shown in Fig.8. Although the defects from thermal spray process are observable, the sound and smooth surface of ground n- Fig. 6 Comparison of surface roughness.n-WC/12Coc-WC/12Con-Al2O3/13TiO2c-Al2O3/13TiO2Wheel speed: 33 m/sFeedrate: 4 mm/sWheel: 600V0 10 20 3000.30.60.91.21.5Depth of cut, mmSurface roughness Ra, 102 nm(a) n-WC/12Co (b) c-WC/12CoFig. 7 SEM observations of ground c/n-WC/12Cocoatings.(a) n-Al2O3/13TiO2 (b) c-Al2O3/13TiO2Fig. 8 SEM observations of ground c/n-Al2O3/13TiO2 coatings.2121210 _mm 2121210 _mm2121210 _mm 2121210 _mm5 Al2O3/13TiO2 coating suggests that ductile flow is a predominant material removal mechanism. Brittle fracture results in rough and fractured surface of ground c-Al2O3/13TiO2 coatings. Chipping and transgranular fracture dominate the surface of ground c-Al2O3/13TiO2 coating. The surface observations explain the above difference in roughness.4 CONCLUSIONS From the comparisons done on grinding force, specific grinding energy, surface finish and surface topography of nanostructured and conventional coatings, it is concluded that the grain size plays a significant role in material removal for grinding.Grinding force, break-in force and specific grinding energy vary inversely with the grain size while the surface roughness increases with the grain size. Both ductile flow and brittle fracture occur during grinding. The grain size influences the extent of ductile flow in grinding, which dominates the final appearance of ground surface. The reduced grain size and richer binder phases enhance both hardness and toughness in nanostructured materials, and therefore influence the grinding of these materials. However, at a higher material removal rate, the influence of grain size becomes insignificant.REFERENCES1 H.P.Kirchner and J.C.Conway. “Mechanisms of material removal and damage penetration during single point grinding of ceramics”. Machining of Ceramic Materials and Components, ASME, NewYork, Vol.17, 1985, pp.55-612 H.K.Tnshoff and E.Brinksmeier. “Abrasives and their influences on force temperature and surface”. Proc. of SME Intl Grinding Conf., Philadelphia,1990, pp.10-123 P.Blake, T.Bifano, T.Dow and R.O.Scattergood. “Precision machining of ceramic materials”. Ceramic Bulletin, Vol.67, No.6, 1988, pp.1038-10444 P.Roth and H.K.Tnshoff. “Influence of microstructure on grindability of alumina ceramics”. Proceedings of the InternationalConference on Machining of Advanced Materials, Gaithersburg MD, July 1993, pp.247-2615 K.Jia, T.E.Fischer and B.Gallois. “Microstructure, hardness and toughness of nanostructured and conventional WC-Co composites”. Nanostructured Materials, Vol.10, No.5, 1998, pp. 875-8916 S.Malkin. “Grinding technology, theory and application of machining with abrasives”. Ellis Horwood Limited, Chichester, England, 1989
收藏