抓斗結(jié)構(gòu)設(shè)計(jì)與優(yōu)化_畢業(yè)設(shè)計(jì)論文

1、抓斗結(jié)構(gòu)設(shè)計(jì)與優(yōu)化目錄1緒論 12抓斗設(shè)計(jì) 2 2 2 3 3 4 45 5 73起升機(jī)構(gòu)設(shè)計(jì) 8 8 8 9 10 11 12 13 14 15 164抓斗優(yōu)化17標(biāo)17設(shè)計(jì)變量1718196總結(jié) 215參考文獻(xiàn) 227致謝 238附錄 24 英文 24 中文翻譯 29抓斗結(jié)構(gòu)設(shè)計(jì)與優(yōu)化摘要 首先應(yīng)該對(duì)抓斗進(jìn)行設(shè)計(jì)計(jì)算，確定抓斗的各個(gè)參數(shù)，然后根據(jù)抓斗的型號(hào)、起重量和給定的起升高度、起升速度，確定起升機(jī)構(gòu)的布置方案，然后確定鋼絲繩的型號(hào)，選取適宜的卷筒、滑輪直徑。根據(jù)設(shè)計(jì)計(jì)算選定減速器、電動(dòng)機(jī)、制動(dòng)器和聯(lián)軸器。根據(jù)設(shè)計(jì)計(jì)算的結(jié)果，繪制出抓斗部件圖和起升機(jī)構(gòu)總體裝配圖。對(duì)抓斗的優(yōu)化主要是通過(guò)M

2、ATLAB語(yǔ)言，將前面已經(jīng)設(shè)計(jì)好的抓斗參數(shù)轉(zhuǎn)化為線性方程，這個(gè)過(guò)程和其它調(diào)式程序一樣，主要包括這樣幾個(gè)步驟：編輯.編譯.連接.以及執(zhí)行和調(diào)試。利用MATLAB軟件可以求解線性規(guī)劃、無(wú)約束規(guī)劃、二次規(guī)劃和有約束非線性規(guī)劃等優(yōu)化設(shè)計(jì)問(wèn)題.該軟件編程工作量小,初始參數(shù)輸入簡(jiǎn)單,符合工程設(shè)計(jì)語(yǔ)言,有著很大的優(yōu)越性.通過(guò)給出的優(yōu)化實(shí)例可以看出,應(yīng)用該軟件求解機(jī)械優(yōu)化設(shè)計(jì)問(wèn)題非常方便。主要詞匯：抓斗.優(yōu)化. Design and optimization for the grab of structuralAbstractFirst should carry on the design calculati

3、on to the grab, definite grab each parameter, then according to the grab model, the lifting capacity and assigns lifts, lifts highly the speed, determined lifts the organization scheme of arrangement, then the determination steel wire model, selects the appropriate reel, the pulley diameter. Accordi

4、ng to design calculation designation reduction gear, electric motor, brake and shaft coupling. According to the design calculation result, draws up the grab part chart and lifts the organization overall assembly drawing.To the grab optimization mainly is through the MATLAB language, front already wi

5、ll design the grab parameter transformed as the linear equation, this process and other mode procedure were same, mainly included such several steps: Edition.Translation.Connection.As well as execution and debugging. May solve the linear programming, the non-restraint plan, two plans using the MATLA

6、B software and has optimized design questions and so on restraint nonlinear programming.This software programming work load is small,The initial parameter input is simple,Conforms to the engineering design language,Has the very big superiority.Through the optimized example which gives may see,Solves

7、 the machinery using this software to optimize the design question to be extremely convenient.Main glossary: Grab. Optimization. Parameter. Procedure1緒論隨著社會(huì)的日益開(kāi)展，一些強(qiáng)度較大的體力勞動(dòng)逐漸被機(jī)械生產(chǎn)所替代，起重機(jī)那么是其中運(yùn)用較廣泛的機(jī)械，它對(duì)減輕勞動(dòng)強(qiáng)度，節(jié)省人力，降低建設(shè)本錢(qián)，提高施工質(zhì)量，加快建設(shè)速度，實(shí)現(xiàn)工程施工機(jī)械化起著十分重要的作用。抓斗是起重機(jī)上十分重要部件，它是用來(lái)裝卸物料的裝置，而抓斗的重量，形狀，大小也將對(duì)取物能力

8、有著重要影響，這里也將會(huì)對(duì)它進(jìn)行優(yōu)化，使它的性能得到進(jìn)一步的提高。通過(guò)司機(jī)室那的操作，抓斗能進(jìn)行抓取和開(kāi)卸動(dòng)作，大大提高了工作效率，所以廣泛的運(yùn)用于生產(chǎn)實(shí)踐中。在起重機(jī)中，用以提升或下降貨物的機(jī)構(gòu)稱(chēng)為起升機(jī)構(gòu)。起升機(jī)構(gòu)是起重機(jī)中最重要、最根本的機(jī)構(gòu)，其工作的好壞直接影響整臺(tái)起重機(jī)的工作性能。起升機(jī)構(gòu)一般由驅(qū)動(dòng)裝置、鋼絲繩卷繞系統(tǒng)、取物裝置和平安保護(hù)裝置等組成。驅(qū)動(dòng)裝置包括電動(dòng)機(jī)、聯(lián)軸器、制動(dòng)器、減速器、卷筒等部件。此次設(shè)計(jì)主要是針對(duì)抓斗的結(jié)構(gòu)設(shè)計(jì)、起升機(jī)構(gòu)的設(shè)計(jì)計(jì)算和對(duì)抓斗的優(yōu)化，首先應(yīng)該對(duì)抓斗進(jìn)行設(shè)計(jì)計(jì)算，確定抓斗的各個(gè)參數(shù)，然后根據(jù)抓斗的型號(hào)、起重量和給定的起升高度、起升速度，確定起升機(jī)構(gòu)

9、的布置方案，然后確定鋼絲繩的型號(hào)，選取適宜的卷筒、滑輪直徑。根據(jù)設(shè)計(jì)計(jì)算選定減速器、電動(dòng)機(jī)、制動(dòng)器和聯(lián)軸器。根據(jù)設(shè)計(jì)計(jì)算的結(jié)果，繪制出抓斗部件圖和起升機(jī)構(gòu)總體裝配圖。對(duì)抓斗的優(yōu)化主要是通過(guò)MATLAB語(yǔ)言，將前面已經(jīng)設(shè)計(jì)好的抓斗參數(shù)轉(zhuǎn)化為線性方程，這個(gè)過(guò)程和其它調(diào)式程序一樣，主要包括這樣幾個(gè)步驟：編輯.編譯.連接.以及執(zhí)行和調(diào)試。利用MATLAB軟件可以求解線性規(guī)劃、無(wú)約束規(guī)劃、二次規(guī)劃和有約束非線性規(guī)劃等優(yōu)化設(shè)計(jì)問(wèn)題.該軟件編程工作量小,初始參數(shù)輸入簡(jiǎn)單,符合工程設(shè)計(jì)語(yǔ)言,有著很大的優(yōu)越性.通過(guò)給出的優(yōu)化實(shí)例可以看出,應(yīng)用該軟件求解機(jī)械優(yōu)化設(shè)計(jì)問(wèn)題非常方便。此次設(shè)計(jì)的主要目的是要通過(guò)對(duì)抓斗和

10、起升機(jī)構(gòu)的設(shè)計(jì)計(jì)算到達(dá)了解起重機(jī)設(shè)計(jì)的過(guò)程的目的，為以后參加工作，從事設(shè)計(jì)工作打下一個(gè)堅(jiān)實(shí)的根底。熟練掌握了AUTOCAD的操作和利用MATLAB語(yǔ)言進(jìn)行優(yōu)化。2抓斗設(shè)計(jì)抓斗是起重機(jī)裝卸散料的一種取物裝置。主要用于大量散粒物品的裝卸工作，采用抓斗可免除繁重的人工勞動(dòng)，提高勞動(dòng)生產(chǎn)率。21抓斗類(lèi)型的種類(lèi) 為了便于設(shè)計(jì)和選用，可按抓取物料容重r，初選電動(dòng)機(jī)能夠滿足不過(guò)熱條件。 電動(dòng)機(jī)轉(zhuǎn)速 3-6傳動(dòng)比 查文獻(xiàn)3表15-11，選用ZQ650，中級(jí)工作制，同步轉(zhuǎn)速為750r/min時(shí)，許用功率N=95kw，i=，減速器自身質(zhì)量，輸入軸直徑 圓錐形軸端長(zhǎng)，輸出軸直徑，軸端長(zhǎng)。 圖8 減速器示意圖 貨物實(shí)

11、際起升速度：減速器輸出軸強(qiáng)度校核：輸出軸最大徑向力 3-7式中 為卷筒與軸的自身重力，減速器輸出軸最大徑向力許用值R=86700N輸入軸最大扭矩 3-8式中電動(dòng)機(jī)最大扭矩倍數(shù)；i為減速器的傳動(dòng)比；為減速器的效率。減速器輸出軸的許用扭矩?fù)?jù)此， 該減速器能滿足設(shè)計(jì)要求。制動(dòng)器的選擇起升機(jī)構(gòu)制動(dòng)器的制動(dòng)力矩必須大于由貨物產(chǎn)生的靜力矩，使貨物處于懸吊狀態(tài)時(shí)具有足夠的平安，下降靜轉(zhuǎn)矩為：查制動(dòng)器標(biāo)準(zhǔn)，選用YDWZ-300/45制動(dòng)器，其額定制動(dòng)轉(zhuǎn)矩制動(dòng)輪直徑D=400mm，制動(dòng)器自身質(zhì)量 圖9 制動(dòng)器高速軸的計(jì)算扭矩 3-11式中，n聯(lián)軸器平安系數(shù)，取 ； 剛性動(dòng)載系數(shù)，一般=1.8。根據(jù)電動(dòng)機(jī)軸和減速

12、器輸入軸的軸徑，分別選用CLZ2型半齒輪聯(lián)軸器和帶制動(dòng)輪的齒輪聯(lián)軸器。據(jù)聯(lián)軸器標(biāo)準(zhǔn)， CLZ2半齒輪聯(lián)軸器最大允許扭矩 ，飛輪矩，自身質(zhì)量 ，制動(dòng)輪直徑D=200的帶制動(dòng)輪齒輪聯(lián)軸器最大允許扭矩飛輪矩 ，自身質(zhì)量輸入軸直徑，輸出軸直徑。 圖10 聯(lián)軸器前面的計(jì)算都是考慮機(jī)構(gòu)處于穩(wěn)定運(yùn)動(dòng)狀態(tài)時(shí)的精力計(jì)算。眾所周知，起重機(jī)是一種間歇?jiǎng)幼鞯臋C(jī)械，工作是周期性的。在每個(gè)工作循環(huán)中，起升機(jī)構(gòu)也被斷續(xù)地開(kāi)動(dòng)與停止，而每次開(kāi) 動(dòng) 過(guò)程中又都包括有啟動(dòng)加速、穩(wěn)定運(yùn)動(dòng)等速及制動(dòng)減速三個(gè)時(shí)期。在啟動(dòng)和制動(dòng)時(shí)期，機(jī)構(gòu)作變速運(yùn)動(dòng)，因而 有加速度與慣性力的作用。當(dāng)啟動(dòng)、制動(dòng)時(shí)間過(guò)長(zhǎng)時(shí)，加速度固 然很小，但這會(huì)影響起重機(jī)

13、的生產(chǎn)率；而啟動(dòng)、制動(dòng)時(shí)間過(guò)短時(shí)，加速度太大，會(huì)給金屬結(jié)構(gòu)和機(jī)械局部帶來(lái)很大的動(dòng)力載荷。因而必須把啟動(dòng)與制動(dòng)時(shí)間控制在一定的范圍內(nèi)。起動(dòng)時(shí)間：機(jī)構(gòu)起動(dòng)時(shí)間電動(dòng)機(jī)必須發(fā)出較大的力矩，即起動(dòng)力矩，使原來(lái)靜止的質(zhì)量開(kāi)始運(yùn)動(dòng)。這時(shí)起動(dòng)力矩除了克服靜阻力矩外，還有一局部力矩使運(yùn)動(dòng)質(zhì)量加速。這局部力矩愈大，加速的時(shí)間就愈短。 3-9式中J-起升時(shí)換算到電動(dòng)機(jī)軸上的總轉(zhuǎn)動(dòng)慣量 3-10-高速軸上旋轉(zhuǎn)質(zhì)量的轉(zhuǎn)動(dòng)慣量。通常380t通用橋式起重機(jī)，=12s，上述起動(dòng)時(shí)間符合電動(dòng)機(jī)起動(dòng)要求。制動(dòng)時(shí)間驗(yàn)算制動(dòng)時(shí)間：制動(dòng)時(shí)，制動(dòng)器的制動(dòng)力矩促使運(yùn)動(dòng)質(zhì)量減速。下降制動(dòng)是制動(dòng)時(shí)間較長(zhǎng)，故通常計(jì)算下降時(shí)的制動(dòng)時(shí)間 3 -11

14、T所以制動(dòng)時(shí)間符合要求。 4 抓斗優(yōu)化優(yōu)化目標(biāo)抓斗抓取散料需要能量,長(zhǎng)撐桿抓斗的這個(gè)能量主要通過(guò)閉合繩拉力及抓斗重心的垂直運(yùn)動(dòng)引起的重力勢(shì)能的改變獲得。閉合繩拉力通過(guò)抓斗機(jī)構(gòu)產(chǎn)生抓取能力。假設(shè)合理匹配機(jī)構(gòu)幾何尺寸,使相同開(kāi)度下單位閉合繩拉力產(chǎn)生的抓取力提高,將有利于減輕抓斗自重,提高抓取比。因此,取抓斗單位閉合繩拉力產(chǎn)生的抓取力為抓斗機(jī)構(gòu)的優(yōu)化目標(biāo)。圖12為抓斗機(jī)構(gòu)簡(jiǎn)圖。閉合繩拉力在顎板張開(kāi)角為時(shí)的抓取力為: 圖12 抓斗機(jī)構(gòu)簡(jiǎn)圖 4-1式中 常數(shù)；閉合滑輪組單個(gè)滑輪效率；顎板底背角；閉合滑輪組倍率；抓斗最大開(kāi)度；其余符號(hào)意義見(jiàn)圖12。長(zhǎng)度均以m為單位,角度以弧度為單位。單位閉合繩拉力產(chǎn)生的抓

15、取力 4-2 抓斗機(jī)構(gòu)簡(jiǎn)圖式說(shuō)明,在抓斗閉合過(guò)程中,當(dāng)顎板張開(kāi)角不同時(shí),即使是同一抓斗機(jī)構(gòu), 也不相同。在抓斗閉合初期,增大有利于減緩閉合繩拉力的增加,可以在較小的閉合繩拉力時(shí)有較大的抓取力,增加抓斗的下沉力。在抓斗寬度不變時(shí),增加挖掘深度,提高深挖能力;或者可以采用較寬的抓斗。總之,可以提高抓斗在閉合初期的抓貨量。在抓斗閉合末期,增大可以獲得較大的水平閉合力,有利于將抓到的散料壓入顎板中,提高抓斗在閉合后期的填充能力。因此,一個(gè)理想的抓斗機(jī)構(gòu)應(yīng)當(dāng)具有這樣的特征:在抓斗閉合過(guò)程中的每一位置上, 均應(yīng)到達(dá)極大值。由于C為常數(shù),令 4-3那么,長(zhǎng)撐桿抓斗機(jī)構(gòu)的優(yōu)化函數(shù)為等價(jià)與 4-44.2設(shè)計(jì)變量

16、 決定優(yōu)化目標(biāo)的獨(dú)立變量只有, ,及,并令, , , ,它們構(gòu)成了抓斗機(jī)構(gòu)優(yōu)化設(shè)計(jì)的設(shè)計(jì)變量。4.3約束條件散料動(dòng)態(tài)堆積角,抓斗最大張開(kāi)度L=2734mm。=0.32, =0.5, =0.125, =0.43, =/5。a防止閉合滑輪組之間滑輪干預(yù),或防止繞入、繞出滑輪的鋼繩偏角過(guò)大,限制上、下橫梁滑輪組軸線之間最小距離。 4-5b防止閉合狀態(tài)下?lián)螚U力臂過(guò)小。 4-6(c)防止最大張開(kāi)度狀態(tài)下,撐桿力不產(chǎn)生抓取力。 (d)保證抓斗結(jié)構(gòu)緊湊。 4-7 4-8 4-9 4-10(e)保證目標(biāo)函數(shù)有意義,設(shè)計(jì)變量非負(fù)等其它要求。 4-11 4-12 (j=1,2,3,) 4-13其中,和控制閉合滑輪

17、組上、下滑輪軸閉合狀態(tài)下最小及最大距離,控制抓斗機(jī)構(gòu)最大寬度,與閉合滑輪組滑輪大小有關(guān),為散料動(dòng)態(tài)堆積角。根據(jù)設(shè)計(jì)需要，使用比擬常見(jiàn)MATLAB語(yǔ)言作為編程工具。首先用MATLAB編寫(xiě)目標(biāo)函數(shù)的m文件objfun.m，返回x處的函數(shù)值f。%抓斗優(yōu)化程序；function y=objfun(x)f=0.854*x2(sin(x(4)+0.628)-cos(x(4)+0.628)*(2743*x(2)sin(x(4)+0.628)-2743x(3)/(2775*x(1)2-(2743x(2)2*sin(x(4)+0265)-2743*x(3)2)0.5)；由于約束條件中有非線性約束，需要編寫(xiě)一個(gè)描

18、述非線性約束條件的M文件confun.m。%優(yōu)化約束；function c,ceq=confun(x)；c= x(1)2-(x(2)sin(x(4)-x(3)2-(x(2)cos(x(4)+0.32)2/x(2)sin(x(4)-x(3)/(x(1)+x(2)cos(x(4)-0.265)-x(3)/0.5-x(2)/0.125-x(3)/1.57-0.12-x(4)/(x(2)*sin(x(4)-x(3)2+9x(4)cos(x(4)+0.43)2-x(1)2/x(1)+x(3)-x(2)/x(4)-0.265; ceq=;x0=;options=optimset(largescale,of

19、f);x,fval=fmincon(objfun,x0,confun,options) 輸出最優(yōu)點(diǎn)和目標(biāo)函數(shù)值：x(1)= x(2)= x(3)=x(4)=與原設(shè)計(jì)方案x=(0.6079468,0.3895086,0.04861361,0.9827937)下目標(biāo)函數(shù)進(jìn)行比擬,在整個(gè)抓取過(guò)程中,優(yōu)化方案單位閉合繩拉力產(chǎn)生的抓取力比原方案提高25%31%?？?結(jié)經(jīng)過(guò)三個(gè)多月設(shè)計(jì)，對(duì)起重機(jī)抓斗有了比擬整體的認(rèn)識(shí)，了解起重機(jī)抓斗和起升機(jī)構(gòu)的根本組成和各局部的功用、原理。本次設(shè)計(jì)的任務(wù)主要是對(duì)起重機(jī)起升機(jī)構(gòu)設(shè)計(jì)及對(duì)抓斗的優(yōu)化。設(shè)計(jì)先對(duì)抓斗進(jìn)行系統(tǒng)的設(shè)計(jì)計(jì)算，然后根據(jù)抓斗計(jì)算出的參數(shù)和給定的參數(shù)再對(duì)起重機(jī)

20、的起升機(jī)構(gòu)進(jìn)行設(shè)計(jì)，參考相關(guān)書(shū)籍，選擇一個(gè)合理的布置方案。通過(guò)計(jì)算選用機(jī)構(gòu)中所需的標(biāo)準(zhǔn)部件如電動(dòng)機(jī)、制動(dòng)器、減速器、聯(lián)軸器、鋼絲繩等，對(duì)非標(biāo)準(zhǔn)零件還須作進(jìn)一步的強(qiáng)度與風(fēng)度計(jì)算校核。對(duì)抓斗的優(yōu)化主要是通過(guò)MATLAB語(yǔ)言，將前面已經(jīng)設(shè)計(jì)好的抓斗參數(shù)轉(zhuǎn)化為線性方程，這個(gè)過(guò)程和其它調(diào)式程序一樣，主要包括這樣幾個(gè)步驟：編輯.編譯.連接.以及執(zhí)行和調(diào)試。利用MATLAB軟件可以求解線性規(guī)劃、無(wú)約束規(guī)劃、二次規(guī)劃和有約束非線性規(guī)劃等優(yōu)化設(shè)計(jì)問(wèn)題.該軟件編程工作量小,初始參數(shù)輸入簡(jiǎn)單,符合工程設(shè)計(jì)語(yǔ)言,有著很大的優(yōu)越性.通過(guò)給出的優(yōu)化實(shí)例可以看出,應(yīng)用該軟件求解機(jī)械優(yōu)化設(shè)計(jì)問(wèn)題非常方便。通過(guò)本次設(shè)計(jì)，對(duì)機(jī)械

21、設(shè)計(jì)的過(guò)程和步驟有了一個(gè)很清晰的認(rèn)識(shí)。由于時(shí)間比擬倉(cāng)促，優(yōu)化效果并沒(méi)有到達(dá)最正確水準(zhǔn)，但是通過(guò)設(shè)計(jì)還是了解了制作的全部過(guò)程，到達(dá)了設(shè)計(jì)的預(yù)期目的。參 考 文 獻(xiàn)1 張質(zhì)文、虞和謙等. 起重機(jī)設(shè)計(jì)手冊(cè)M. 北京：中國(guó)鐵道出版社. 19982 東北大學(xué)?機(jī)械零件設(shè)計(jì)手冊(cè)?編寫(xiě)組. 機(jī)械零件設(shè)計(jì)手冊(cè)M. 北京：冶金工業(yè)出版社. 1994MM5 顧迪民. 工程起重機(jī)M. 北京：中國(guó)建筑工業(yè)出版社. 19886 M7 MM9 單祖輝. 材料力學(xué)M. 北京：高等教育出版社. 200110 洪家娣、李明、黃興元,機(jī)械設(shè)計(jì)指導(dǎo)M.南昌：江西高等學(xué)校出版社.2001.1211J致 謝 首先感謝我的指導(dǎo)老師程賢福

22、老師，感謝他給我無(wú)限的幫助和關(guān)心。感謝學(xué)校給我提供良好的設(shè)計(jì)環(huán)境，讓我有一個(gè)安靜的設(shè)計(jì)教室，給我一個(gè)可以隨時(shí)查閱資料的圖書(shū)館，感謝其它給過(guò)我?guī)椭睦蠋熀屯瑢W(xué)。他們認(rèn)真細(xì)心的改正我們?cè)O(shè)計(jì)上犯的錯(cuò)誤，身行言教的告訴我們?cè)诳茖W(xué)上要保持嚴(yán)謹(jǐn)、認(rèn)真的良好作風(fēng)，并為我在設(shè)計(jì)中出現(xiàn)的問(wèn)題提供了很好的建議。在我們遇到困難時(shí)，兩位指導(dǎo)老師會(huì)幫助我們克服困難，戰(zhàn)勝困難?？傊诩磳厴I(yè)之際，謹(jǐn)在此對(duì)指導(dǎo)老師致以最誠(chéng)摯的謝意。還要感謝同組的其他同學(xué)，大家相互幫助，共同努力，克服了一個(gè)又一個(gè)的困難，最終完成畢業(yè)設(shè)計(jì)。特別要感謝與我同做畢業(yè)設(shè)計(jì)的同學(xué)。在此我還要感謝我的家庭對(duì)我的支持，使我順利的完學(xué)業(yè)。 附錄A:外文資

23、料原文局部 Evaluating bridge and gantry cranesAbstract (Document Summary)Properly sized, designed, and installed bridge and gantry cranes dramatically increase production, significantly reduce material handling costs, and substantially lower the risk of employee injury. A properly maintained crane lasts

24、at least 20 years, could reach 50 years or more, and occasionally outlives the structure or company originally housing or using the equipment. Bridge cranes are available in top running and underhung configurations, and single or double girder, to match plant structural and lifting requirements. Gan

25、try cranes are constructed in single or double leg, single or double girder, and top running or underhung versions. Bridge cranes are usually used for high tonnages, long spans, and heavy duties. Gantry cranes are often a practical alternative to bridge cranes, and are capable of serving many of the

26、 same lifting, traveling, and duty classifications. Gantries are suitable if the plant structure cannot handle the bridge loadingFull TextRelates to build up to the assembly pulley that suspends the ministry on coop peak consists of admittedly stably that the master who suspends the ministry on coop

27、 peak being living advances idle wheel and two assisting direction idles wheel 。The wire rope on the hoister coil near the direction idle wheel on the hoister side load-bearing beam successively 、Suspend coop peak ministry the assisting direction idle wheel 、Master advances the idle wheel 、Another s

28、ide assisting direction idle wheel ，Admittedly afterwards being living stably on another load-bearing beam ，Constituteing suspends the coop to advance the system 。Suspending on the coop horn separately fixs berthhing the unit ，That unit stirs a string Gou in the interest of automate either hand ，Whe

29、n suspending the coop to berth ，Turns that unit causes it string to headframe master vertical column and fiercely fastens on the staff ，Geing up to ascend the wire rope does not accept force 。Once the wire rope snaps ，The automatic pellet of that unit is turned on buckleing at the primary vertical c

30、olumn and fiercely fastens on the staff ，Avert suspending the coop to drop 。Control cabin leans on a part of the body side to fix four idles wheel ，Cause to dominate the cabin may go up and down along the guide in shelf part of the body outside ，Convenient operator is living , and the hoister to sur

31、face of the earth of upper air is dominateeed 。Copyright Cahners Business Information, a division of Reed Elsevier, Inc. Apr 2001 Properly sized, designed, and installed bridge and gantry cranes dramatically increase production, significantly reduce material handling costs, and substantially lower t

32、he risk of employee injury. A properly maintained crane lasts at least 20 yr. could reach 50 yr or more, and occasionally outlives the structure or company originally housing or using the equipment. These overhead workhorses maneuver large, bulky loads through the plant for shipping and receiving, r

33、elocating and staging, or integrating with heavy-duty manufacturing operations. Computers and other control packages near the equipment or at a remote location allow the crane to closely match almost any size and type of load, where and when needed, and under all operational and environmental condit

34、ions. Hoisting speeds over 200 fpm, bridge speeds to 1000 fpm, and capacities over 1000 tons are available, although slower movements and smaller loads are the norm. Cranes are 15-30-ft overhead, but could be up to 200 ft to clear floor-mounted equipment, to place material where needed in the manufa

35、cturing operation, or for safety reasons. A variety of mechanisms, such as hooks, magnets, or buckets, are available on the hoist to match particular grabbing or lifting requirements. Types Bridge cranes are available in top running and underhung configurations, and single or double girder, to match

36、 plant structural and lifting requirements. Gantry cranes are constructed in single or double leg, single or double girder, and top running or underhung versions. Bridge cranes are usually used for high tonnages, long spans, and heavy duties. Although available in several forms, each crane design co

37、ntains several pieces of common equipment. * Hoists are used to lift and lower the load. * Trolleys consist of a frame, end trucks or wheels with side frames, and drive. They suspend or support the hoist, rope, and load block; and travel on one or more bridge rails or beams. * Girders are the princi

38、pal horizontal structural steel beams holding the hoist and trolley. They are supported by end trucks and are perpendicular to the runway. Very wide or large capacity cranes require two or more girders. * Runways consist of structural steel rails, girders, brackets, and framework. They support and a

39、llow movement of the crane through the plant. * End trucks are an assembly of structural members, wheels, bearings, and axles that support the girders or trolley cross members. * Bridges consist of girders, end trucks, walkways, cross bridge electrification controls, and drive mechanisms. They carry

40、 the trolley and travel along the runway rails. Gantry cranes are often a practical alternative to bridge cranes, and are capable of serving many of the same lifting, traveling, and duty classifications. This floor-mounted equipment essentially bridges the lifting and moving service area as the cran

41、e rolls down a predetermined path on legs. Gantries are suitable if the plant structure cannot handle the bridge loading, if the installation is temporary and may require relocation at a later date, or overhead runways are long, costly to erect, and difficult to maintain in alignment. The gantry is

42、common in situations where the crane itself does little or no traveling, and material transfer is handled almost exclusively by the trolley. Top-running double girder Top-running, double-girder cranes provide the greatest lifting capacities, highest tonnages, widest spans, and heaviest duties. Top-r

43、unning single girder Top-running, single-girder cranes have a one-beam bridge that rides on a rail atop the runway and handle loads up to 30 tons with spans up to 60 ft. Double-girder underhung Double-girder underhung cranes have the hoist mounted above the bridge to attain a bit more headroom and r

44、each capacities up to 50 tons. Single-girder underhung Single-girder underhung cranes have the bridge end trucks running on the lower flanges of the runway beams and are usually limited to 10 tons. Double-leg gantry Double-leg gantry cranes move along floor rails or guidepaths with a capacity typica

45、lly less than 30 tons, although units reaching several hundred tons are in service. Single-leg gantry Single-leg gantry cranes substitute a wall-mounted runway for the second leg and are usually designed to handle loads of less than 20 tons for a specific operation. Single and double-leg, single-gir

46、der cranes typically handle less than 20 tons, although models that accommodate up to about 60 tons are available with special construction features. The two double-girder types usually have capacities less than 30 tons, but again, exceptions exist and some versions moving several hundred tons are i

47、n service. Sidebar Safety first Sidebar Safe crane operation is an issue of paramount importance. Components such as redundant brake concepts for hoists, more reliable controls, and economical overload detection systems are engineered into the cranes to help in the safety process. Even with this equ

48、ipment available, safety starts with the operator. Whenever there is doubt as to safety, the operator should stop the crane, report the problem to a supervisor, and not operate the equipment until satisfied it is safe to do so, or is directed to proceed by a supervisor. Operators should be familiar

49、with the principal parts of the crane. Employees should receive hands- on training, read all instruction materials, and have a thorough knowledge of crane control functions and movements. The operator should test all crane controls at the beginning of each shift, and should perform a walk-around che

50、ck to look for loose or damaged parts before commencing work. There is a variety of other safety factors to consider. * When the load approaches the rated capacity, the operator should test the hoisting brakes by raising the load a few inches and applying the brakes. * The load should not be lowered

51、 below the point where less than two full wraps of wire rope remain on the hoist drum. Sidebar * The operator should land any attached load and place the controllers in the off position when leaving a crane unattended. * Loads should never be carried over workers heads. * Cranes should never be used

52、 for side pulling. * Hand signals between the operator and hooker should be clearly agreed upon and understood before moving a load. * The operator should never lift two separately rigged loads at the same time. * The operator should approach the desired position as far as possible at the main speed

53、 and use creeping for final positioning. Ropes,pulleys and drumsSteel Wire Ropes Steel wire ropes are used as flexible appliances to lift loads and transmit motion and forces.Such ropes are wound from steel wire from 0.5 mm to 2 mm in diameter and have an ultimate strength of 14002000N/mm2.Steel wir

54、e ropes are available in a great variety of designs. Machines used in amterials handling,construction and road making are provided mostly with round double lay (cross or regular lay)ropes from 11mm to 32 mm in dismeter.Double lay ropes are manufactured from preliminarily twisted spiral wire strands.

55、In a parallel (Long)lay rope the direction of twist of the direction of twist of the wires in the strand is the same as that of the atrands in the rope,while regular lay ropes are so constructed that the direction of twist of the wires in the strand is opposite to that of the strands in the rope.To

56、make the ropes more flexible and provde proper lubrication of wires the strands are laid on a hemp core impregnated with oil.Special locked-coil steel wire ropes find application in cable cranes and cable ways . These ropes ,used to carry trolleys,have the cross section.The outer specially shaped wi

57、res form a smooth surface.These ropes have a low flexibility and high resistance to wear and keep out moisture.According to the regulations of State Technical Inspector,ropes are selected from the formulaQ=S/nWhere： s:breaking load on the rope as a whole;Q:safe load on the rope;n:rope safety factor.

58、lleys and DrumsRopes are supported and guided by means of cast iron pulleys.The groove on the pulley rim is shaped so as not to pinch the rope.The nominal diameter of the pulley D is the diameter of the circle described by the exis of the rope.The pulley diameter appreciably affects the magnitude of

59、 the bending stresses and the rope servive life and for this reason the existing norms should be taken into account in selecting a pulley diameter.During lifting or other displacement of the load the rope may be wound around drums in the form of cylinders with a smooth or grooved surface.A rope rest

60、ing in a groove ensures, besides the proper direction , a smaller pressure on separate wires in the rop which increase the rop service life.The rope capacity of a drum with a single-layer winding can be found from the formulaL1=(D+d)ztWhere D:drum diameter;d:rope diameter;z:number of working turns o