橋式起重機橋架結構設計

橋式起重機橋架結構設計,橋式起重機,結構設計 *學院*屆畢業(yè)設計說明書第一章 緒論1.1 課題的背景由于工業(yè)生產規(guī)模不斷擴大，生產效率日益提高，以及產品生產過程中物料裝卸搬運費用所占比例逐漸增加，促使大型或高速起重機的需求量不斷增長，起重量越來越大，工作速度越來越高，并對能耗和可靠性提出更高的要求。起重機已成為自動化生產流程中的重要環(huán)節(jié)。起重機不但要容易操作，容易維護，而且安全性要好，可靠性要高，要求具有優(yōu)異的耐久性、無故障性、維修性和使用經濟性,起重機的出現大大提高了人們的勞動效率，以前需要許多人花長時間才能搬動的大型物件現在用起重機就能輕易達到效果，尤其是在小范圍的搬動過程中起重機的作用是相當明顯的。橋式起重機作為起重機的一種，是現代工業(yè)生產和起重運輸中實現生產過程機械化、自動化的重要工具和設備，可減輕操作者的勞動強度，提高生產率。橋式起重機在工礦企業(yè)、鋼鐵化工、鐵路交通、港口碼頭以及物流周轉等部門和場所均得到廣泛的運用，它是人們生產活動中不可缺少的一種設備。1.2國內外橋式起重機現狀與發(fā)展前景1.2.1 國內起重機現狀經過幾十年的發(fā)展，我國橋式起重機行業(yè)已經形成了一定的規(guī)模，市場競爭也越發(fā)激烈。橋式起重機行業(yè)在國內需求旺盛和出口快速增長的帶動下，依然保持高速發(fā)展，產品幾近供不應求盡管我國起重機行業(yè)發(fā)展迅速，但是國內起重機仍缺乏競爭力。從技術實力看，與歐美日等發(fā)達地區(qū)相比，中國的技術實力還有一定差距。目前，過內大型起重機尚不具備大量生產能力。從產品結構看，由于技術能力所限，中國起重機在產品結構上也不完善，難以同國外匹敵。同時我國起重行業(yè)目前存在幾個突出問題，歸納如下： （1）整體技術含量偏低，突出表現在產品的品種規(guī)格少，性能、可靠性等指標低于發(fā)達國家同類產品的水平。 （2）知名品牌寥寥無幾，能打入國際市場并享有一定聲譽的知名品牌幾乎沒有。（3）產品低價惡性競爭嚴重，企業(yè)合理利潤難保，已嚴重制約企業(yè)生產技術的持續(xù)發(fā)展。1.2.2 國外起重機發(fā)展前景近年來，隨著國際合作的增加，國際起重機行業(yè)發(fā)展迅速。到目前為止，國際主要知名起重機制造廠商有德國的DEMAG起重機，芬蘭的Kone起重機，美國CM集團等。上述企業(yè)在起重機行業(yè)內較為知名。橋式起重機的更新和發(fā)展，在很大程度上取決于電氣傳動與控制的改進。將機械技術和電子技術相結合，將先進的計算機技術、微電子技術、電力電子技術、光纜技術、液壓技術、模糊控制技術應用到機械的驅動和控制系統(tǒng)，實現起重機的自動化和智能化。大型高效橋式起重機新一代電氣控制裝置已發(fā)展為全電子數字化控制系統(tǒng)。主要由全數字化控制驅動裝置、可編程序控制器、故障診斷及數據管理系統(tǒng)、數字化操縱給定檢測等設備組成。變壓變頻調速、射頻數據通訊、故障自診監(jiān)控、吊具防搖的模糊控制、激光查找起吊物重心、近場感應防碰撞技術、現場總線、載波通訊及控制、無接觸供電及三維條形碼技術等將廣泛得到應用。使起重機具有更高的柔性，以適合多批次少批量的柔性生產模式，提高單機綜合自動化水平。重點開發(fā)以微處理機為核心的高性能電氣傳動裝置，使起重機具有優(yōu)良的調速和靜動特性，可進行操作的自動控制、自動顯示與記錄，起重機運行的自動保護與自動檢測，特殊場合的遠距離遙控等，以適應自動化生產的需要隨著現代科學技術的發(fā)展，各種新技術、新材料、新結構、新工藝在橋式起重機上得到廣泛的應用。所有這些因素都有里地促進了橋式起重機的發(fā)展。根據國內外現有橋式起重機產品和技術資料的分析，近年來橋式起重機的發(fā)展趨勢主要體現在以下幾個方面：（1）重點產品大型化，高速化和專用化（2）系列產品模塊化、組合化和標準化（3）通用產品小型化、輕型化和多樣化（4）產品性能自動化、智能化和數字化（5）產品組合成套化、集成化和柔性化1.3 本設計的主要內容、目標和方法(1)主要內容：了解橋式起重機的發(fā)展和應用現狀，設計50/10t雙梁橋式起重機的橋架結構，并用Solidworks繪圖軟件繪制出橋架結構的三維結構圖和二維結構圖。設計開始時，根據橋式起重機的跨度和起重量查閱起重機設計手冊確定橋架結構的基本參數及主端梁的結構尺寸，再根據基本參數查閱起重機設計手冊確定主端梁所受的各種內力載荷、穩(wěn)定性及上拱度等并逐一進行校核。(2)目標：本文完成了50/10t25.5m偏軌雙梁橋式起重機主端梁等橋架結構各構件的設計驗算。功能實現合理，結構簡單適用，工作可靠。(3)方法：本設計采用規(guī)范的設計計算對橋式起重機各機構進行了分析。首先，通過查閱相關書籍和資料，學習橋式起重機的相關知識，了解橋式起重機的發(fā)展和應用現狀，掌握橋式起重機金屬結構的設計方法，學習并掌握Solidworks繪圖軟件的使用，掌握一般的繪圖方法和計算分析步驟；其次，根據現今國內外生產橋式起重機采用的各種結構類型，結合課本知識和參考文獻信息，設計符合使用要求的結構；然后，根據參考文獻8和參考文獻10，分析橋式起重機的受力情況，計算橋式起重機的自重載荷、起升載荷、水平慣性載荷，并對橋式起重機的抗傾覆穩(wěn)定性進行校核，檢驗結構的靜剛度、強度和穩(wěn)定性。本文還對結構進行了Solidworks三維和二維繪圖，便于生產制造。第二章 橋式起重機偏軌箱型雙梁橋架總體設計2.1 基本參數橋架形式為雙梁橋架，軌道放置為偏軌跨度L=25.5m，起重量mQ=50/10t由設計手冊查的起重量在3t50t范圍內起升高度取Hq=16/18m由通用起重機吊鉤類型為重級故取吊鉤起升速度（主/副）vq=13/20m/min根據起重機設計手冊表1-1-9查的，大車運行速度在（70120） m/min范圍內，取vd=90m/min小車軌距K=2.5m，小車軌道方鋼軌道根據起重機的載荷狀態(tài)和利用等級取其工作級別為A6該起重機在室內工作，工作溫度為-2040。2.2主梁尺寸 大車軸距 Bo=m取Bo=5.8m，端梁全長為6.7m。主梁高度 h=（）L=18211500 mm 取h=1600根據機械設計手冊查的：取腹板高度 h0=1600 mm 腹板厚度 1=8 mm副腹板厚度 2=6 mm 翼緣板厚度 0=10mm下翼緣板寬度 b1= b0+20+40=800mm上翼緣板寬度 b2=930主梁總高度 H1=+20=1620 mm主梁寬度 b=(0.40.5)=648810 mm腹板外側間距 b=760 mm=425 mm 且=540 mm，上下翼緣板不相同，分別為10mm930mm及10mm800mm主梁端部變截面長d=3187.5mm，取d=3.15m2.3端梁尺寸端梁高度 H2=810mm，取H2=900mm端梁翼緣板厚度 2=10mm端梁腹板厚度 3=8mm考慮大車輪安裝，端梁內寬b0=360mm總寬 B2=440mm，根據機械設計手冊得，當時，翼緣板處不需要設置任何加勁肋。2.4主、端梁的連接主、端梁采用焊接連接，端梁為拼接式。上翼緣板與主腹板間的承軌角焊縫采用雙面坡口熔透角焊縫，并用深熔焊或清根以保證根部的熔透。主腹板與下翼緣板間的角焊縫采用單面坡口封底焊縫坡口開在腹板外側。副腹板與上下翼緣板間的角焊縫采用外側開坡口，內側角焊縫。2.5橋架結構與主、端梁截面示意圖圖2-1 雙梁橋架結構 圖2-2 主梁截面與端梁截面第三章 主端梁的設計計算3.1 主梁的計算3.1.1載荷與內力計算主梁自重載荷包括：主梁、小車軌道、走臺、欄桿等重量載荷、主梁上的機電設備及操控室的重量載荷等。主梁截面積 A1=10930+160082+80010=39700mm2端梁截面積 A2=440102+90082=23200mm2主梁自重載荷 Fq=kAg=1.278500.039719.81N/m=3668.7N/m小車軌道重量 F=mg=38.869.81=381N/m欄桿等重量 Fl=mlg=1009.81=981N/m主梁的均布載荷 Fq=Fq+F+Fl=5031N/m起升載荷為 =g=490000 N小車自重載荷 =mg=12.129.811000=107910.2 N3.1.2動力效應系數起升沖擊系數 1=1.1動載系數 2=1+0.7vq=1+0.713/60 =1.1517運行沖擊系數 4=1.1+0.058vd =1.1+0.0581.5 =1.1871.193.1.3慣性力計算大、小車都是4個車輪，其中主動輪各占一半，按車輪打滑條件去確定大、小車運行的慣性力一根主梁上的小車慣性力為 Pxg=16343N大車運行起、制動慣性力（一根主梁上）為 FH=16343N PH=N/m =359.4N/m主梁跨端設備慣性力影響小可以忽略。3.1.4偏斜運行側向力一根主梁的重量為 PQ=Fq（L-0.4）=5031（25.5-0.4）N =126278N一根端梁單位長度的重量為 Fq1=kpAg=1.178500.0211849.81N/m =1794.5N/m一根端梁的重量為 PGd=Fq1B=1794.56.7N =12023N一組大車運行機構的重量（兩組對稱配置）為 PGj=mjg=8039.81N=7877N司機室及設備的重量（按合力記）為 PGs=msg=20009.81N=19620N（1）滿載小車在主梁跨中央圖3-1 端梁總輪左側端梁總靜輪壓壓計算 PR1=(PQ+PGx)+(2PQ)+PGs(1-)+PGj+PGd =(323730+107910)+126278+19620(1-)+7877+21023N =379310N由=4.397,查的=0.172側向力為 Ps1=PR1 =3793100.172N=32620.7N（2）滿載小車在主梁左端極限位置左側端梁總靜輪壓為 PR2=(PQ+PGx)（1-）+(2PQ)+PGs(1-)+PGj+PGd =561275.7N側向力為 Ps2=PR2=561275.70.172=48270N故選取大車車輪直徑為800 mm,軌道為QU703.1.5 扭轉載荷計算偏軌箱型梁由Pn和PH的偏心作用而產生移動扭矩，其它載荷PGj、PGs，產生的扭矩較小且作用方向相反，故不計算。 圖 3-2 扭轉載荷計算偏軌箱型梁彎心A在梁截面的對稱形心軸x上（不考慮翼緣外伸部分）彎心至主腹板中線的距離為 e1=(-) = (760-7)mm=322.7mm軌高hg=134mm，故小車軌道選用P38 h”=+hg=(1620+134)mm=944mm 移動扭矩 Tp=Pne1=228800322.7Nmm=73834Nm TH=PHh”=16343944Nmm =15428Nm3.1.6 內力 （1）垂直載荷計算大車傳動側的主梁。在固定載荷與移動載荷作用下，主梁按簡支梁計算，如圖5。圖3-3 主梁計算模型固定載荷作用下主梁跨中的彎矩為 Mq=4 =1.19 =530455Nm跨端剪切力為 Fqc4 =106307.5N移動載荷作用下主梁的內力1）滿載小車在跨中，跨中E點彎矩為 MP=輪壓合力Pn與左輪的距離為 b1= =1.344m則 MP=Nm =1557600Nm跨中E點剪切力為 FP4Pn(1-) =128960.8N跨中內扭矩為 Tn=(4TP+TH)=51645Nm2）滿載小車在跨端極限位置（z=e1）。小車左輪距梁端距離為 c1=e1-L1=0.7m跨端剪切力為 FPc= =1.19 =250447.5N跨端內扭矩為 Tn1=(4TP+TH)(1-) =(1.1973834+15428)Nm =95189Nm主梁跨中總彎矩為 Mx=Mq+Mp=(530455+1557600)Nm =2088055Nm主梁跨端總剪切力（支承力）為 FR=Fc=Fpc+Fqc =(106307.5+250447.5)N=356755N（2） 水平載荷1）水平慣性載荷。在水平載荷PH及FH作用下，橋架按剛架計算。因偏軌箱形梁與端梁連接面較寬，應采取兩主梁軸線間距K代替原小車軌距K構成新的水平剛架，這樣比較符合實際，因此 K=K+2x1=(2.5+20.331)m 3.16m b=K=1.58m a=(Bo-K)=1.32m 圖3-4 水平剛架計算模型 小車在跨中。剛架的計算系數為 r1=1+ =1+ =1.1342跨中水平彎矩（與單梁橋架公式相同） MH= =Nm =70299Nm跨中水平剪切力為 PPHPH=8171.5N跨中軸力為 NH= =N =-7866N小車在跨端?？缍怂郊羟辛?FcH= = =19643.5N2)偏斜側向力。在偏斜側向力作用下，橋架也按水平剛架分析。圖3-5 剛架側向力作用分析這時計算系數為 rs=1+= =1.2948小車在跨中。側向力為 Ps1=0.5PR1=32620.7N超前力為 =N=7419.6N端梁中點的軸力為 =3710N端梁中點的水平剪切力為 Fd1=Ps1=32620.7N =5786.4N主梁跨中的水平彎矩為 Ms= =Nm =4899.3Nm主梁軸力為 Ns1=Ps1-Fd1=26834N 主梁跨中總的水平彎矩為 My=MH+Ms=(70299+4899.3)Nm =75198.3Nm小車在跨端。側向力為 Ps2=48270N超前力為 Pw2=48270.5N =10979N端梁中點的軸力為 Nd=Pw2=5489.5N端梁中點的水平剪切力為 Fd2=Ps2()=48270N =8562.4N主梁跨端的水平彎矩為 Mcs=Ps2a+Fd2b =(482701.32+8562.41.58)Nm =77245Nm主梁跨端的水平剪切力為 Fcs=Pw2-Nd=0.5Pw=5489.5N主梁跨端總的水平剪切力為 FcH=FcH+Fcs=25133N小車在跨端時，主梁跨中水平彎矩組合值較小，不需要計算3.1.7強度需要計算主梁跨中截面危險點的強度(1)主腹板上邊緣危險點的應力主腹板邊至軌頂距離為 hy=hg+0=144mm主腹板邊的局部壓應力為 m=MPa50.57MPa垂直彎矩產生的應力為 01=MPa=101.2MPa水平彎矩產生的應力為 02=MPa=5.9MPa慣性載荷與側向力對主梁產生的軸向力較小且作用方向相反，應力很小，故不計算。主梁上翼緣的靜矩為 Sy=0B1(y1-o.50) =10930(783.6-5)mm3 =7240980mm3主腹板上邊的切應力為 = =MPa =6.84MPa該點的折算應力為 0=01+02=107.1MPa 1= =MPa =93.6MPa =175MPa (2)副腹板下邊緣危險點的應力 2= =MPa =117.3MPa =175MPa(3)下蓋板下邊緣危險點的應力 3=1.15 =MPa =134.5MPa =175MPa(4)主梁跨端的切應力主梁跨端截面變小。為便于主、端梁連接，取腹板高度等于端梁高度hd=900mm，跨端只需計算切應力。1)主腹板。承受垂直剪力Fe及扭矩Tn1.故主腹板中點切應力為 =+主梁跨端封閉截面面積為 A0=（b-7）(h0+0) =753910mm2 =685230mm2代入上式 =MPa =51.15MPa =100MPa副腹板中兩切應力反向可不計算2)翼緣板。承受水平剪應力FcH=25133N及扭矩Tn1=95189Nm =MPa =9.12MPa0根據工作級別A6，應力集中等級K1及材料Q235，查的-1=119MPa,b=370MPa.焊縫拉伸疲勞許用應力為 rl=1.67-1/1-(1-119/0.45370)0.2843MPa =216.3MPa max=108.1MPa0顯然，相同工況下的應力循環(huán)特性是一致的。根據A6和Q235，橫隔板采用雙面連續(xù)貼角焊縫連接，板底與受拉翼緣間隙為50mm，應力集中等級為K3，查的-1=71MPa拉伸疲勞許用應力 rl=1.67-1/1-(1-71/0.45370)0.2842MPa =141.7MPa max=101.6MParl (合格)由于切應力很小，忽略不計3.1.9主梁穩(wěn)定性（1）整體穩(wěn)定性 =2.1360需設置一條縱向加勁肋，不在驗算。翼緣板最大外伸部分=150/10=15 (穩(wěn)定)主腹板 副腹板 故需設置橫隔板及兩條縱向加勁肋，主、副腹板相同，其布置示于圖10。圖3-8 主梁加勁肋設置及穩(wěn)定性計算隔板間距a=1600mm,縱向加勁肋位置 h1=h2=0.2h0=0.21600mm=320mm1）驗算跨中主腹板上區(qū)格I的穩(wěn)定性，區(qū)格兩邊正應力為 1=01+02=(101.2+5.9)MPa=107MPa 2 =01-+02 =65.2MPa =65.2/107= （屬于不均勻壓縮板） 區(qū)格I的歐拉應力為 E=18.6MPa =116.25MPa (b=h1=320mm)區(qū)格分別受1、E和作用的臨界壓應力為 1cr=KE嵌固系數=1.2，=51,屈曲系數K=則 1cr=1.24.912116.25MPa =685.2MPa0.75s=176MPa需修正，則 1cr=s（）=235(1-)MPa =219.8MPa 腹板邊局部壓應力m=50.57MPa壓力分布長c=2hy+50=2(134+10)+50mm=338mm =53,按a=3b計算=3 =0.352區(qū)格I屬雙邊局部壓縮板，板的屈曲系數為 mcr=KmE =1.22.128116.25MPa =296.86Mpa0.75s需修正，則 mcr=235()MPa =200Mpa區(qū)格平均切應力 = =MPa =8.42Mpa由=1600/320=51,板的屈曲系數為 K=5.34+ cr=KE=1.25.5116.25MPa需修正 =767.25MPa =1329MPa0.75s需修正，則 Mpa =227.16MPa MPa=131.15MPa區(qū)格上邊緣的復合應力為 =MPa =93.85MPa=52,區(qū)格的臨界復合應力為cr= =MPa=160MPa cr=160/1.33MPa=120.3MPa cr區(qū)格的尺寸與區(qū)格I相同，而應力較小，故不需要再算。主腹板外側設置短加勁肋，與上翼緣板頂緊以支撐小車軌道，間距a1=400mm.1）驗算跨中副腹板上區(qū)格I的穩(wěn)定性副腹板上區(qū)格I只受1和的作用，區(qū)格兩邊的正應力為 1=01+02 =（101.2+5.9MPa =108.7MPa 2= =MPa =66.9MPa切應力 = =MPa =2.2Mpa（很?。﹨^(qū)格I的歐拉應力為 E=18.6 =18.6MPa =65.4MPa =0.6151 K=4.898 1cr=KE =1.24.89865.4MPa =384.4MPa 1cr0.75s需要修正，則 1cr=235()MPa=208MPa =51,Kr=5.34+=5.5 cr=KE=1.25.565.4MPa =431.6MPa 431.6MPa =747.55MPa0.75s需要修正，則 235()MPa =221MPa cr=MPa=127.6MPa復合應力為 =MPa =108.77MPa=52,區(qū)格I的臨界復合應力為 cr= =MPa =207.94MPa =108.77MPaIx(合格)主、副腹板采用相同的縱向加勁肋63635，A=614.3mm2，Ix1=231700mm4 縱向加勁肋對主腹板厚度中線的慣性矩為 Ix=Ix1+Ae2 =231700+614.349.62mm4 =1742976mm4 Ix= = =1679360mm4Ix Ix=1.5h03 =1.5160083mm4 =1228800mm4Ix (合格) 3.2 端梁計算端梁截面已初步選定，現進行具體計算端梁計算工況取滿載小車位于主梁跨端，大、小車同時運行起、制動及橋架偏斜3.2.1 載荷與內力（1）垂直載荷端梁按修改的剛架尺寸計算B0=5.8m,a=1.32m,b=1.58m,K=2b=3.16m,B=6.7m,a1=0.45m,a2=0.19m,主梁軸線與主腹板中線距離x1=0.33m,主梁最大支承力FR=356755N因為FR作用點的變動引起的附加力矩為 MR=FRx1=3567550.33Nm=117729Nm端梁自重載荷為FQ1=1794.5N/m端梁在垂直載荷作用下按簡支梁計算，如圖11所示圖3-9 垂直載荷下的端梁計算端梁支反力為 Fvd=FR+0.54Fq1B =(356755+0.51.191794.56.7)N =363908.8N截面1-1彎矩 Mx1=Fvd =N =597409Nm剪力Fv1=0截面2-2彎矩 Mx2=Fvda- =363908.81.32-0.51.191794.51.772+117719Nm =594743.5Nm剪力 Fv2=Fvd-4Fq1(a+a1) =363908.8-1.191794.5(1.32+0.45)N =360129N截面3-3 Mx3=0 Fv3=Fvd-4Fq1a1 =(363908.8-1.191794.50.45)N =362948N截面4-4（沿著豎定位板表面） Mx4Fvda2-4Fq1(a+a1)2 =363908.80.19-0.51.191794.5(0.45+0.19)2Nm =68705Nm Fv4Fvd-4Fq1(a1+a2) =363908.8-1.191794.5(0.45+0.19)N =362542N（2）水平載荷端梁的水平載荷有PH、FH、Ps2、Pxg等，亦按簡支梁計算，如圖12所示圖3-10 水平載荷下的端梁計算 截面1-1因Pxg作用點外移引起的附加水平力矩為 Mxg=Pxgx1=163430.33Nm =5393.2Nm彎矩 My1=Pxga+Mxg =(163431.32+5393.2)Nm =26966Nm支反力 FRH= = =12568.1N Fd2=8562.4N剪切力 FH1FRH+Fd2=(12568.1+8562.4)N=21130.5N軸力 Nd=FcH=25133N截面2-2在PH、FH、Ps2及Pxg 水平力作用下，端梁的水平反力為 FHd=FRHPs2+Pxg =(12568.148270+16343)N =77181N 水平剪切力 FH2 =FHd=77181N彎矩 My2=FH2a+Mxg =（771811.32+5393.2）Nm =107272Nm截面3-3水平剪力 FH3=FH2=77181N其他內力小，不計算。3.2.2 強度截面1-1的應力計算需待端梁拼接設計合格后方可進行（按凈截面計）截面2-2截面角點 = =MPa =157.5MPa=175MPa 腹板邊緣 = =MPa =148.92MPa翼緣板對中軸的靜矩為 Sy=8440(450-4)mm3 =1569920mm3 =MPa=15.07MPa 折算應力為 =MPa=151.2MPa截面3-3及4-4端梁支承處兩個截面很近，只計算受力稍大的截面4-4端梁支承處為安裝大車輪角形軸承座而切成缺口并焊上兩塊彎板（14mm130mm）,端部腹板兩邊都采用雙面貼角焊縫，取hj=8mm,支承處高度400mm，彎板兩個垂直面上都焊有車輪組定位墊板（16mm90mm440mm），彎板參與端梁承載工作，支撐處截面（3-及4-4）示于圖13。 圖3-11 端梁支承處截面 y1= =mm =199.6mm y2=200.4mm慣性矩 Ix=3.4296108mm4中軸以上截面靜矩 S=982197mm3上翼緣靜矩 S1=688512mm3下翼緣（彎板）靜矩 S2=703976mm3截面4-4腹板中軸處的切應力為 f=MPa =64.9MPa fS1，可只計算靠彎板的腹板邊的折算應力，該處正應力為 =MPa =37.3MPa切應力 =MPa =46.5MPa折算應力 MPa =88.76MPa (合格)假設端梁支承水平剪力只由上翼緣板承受，不計入腹板上翼緣板的切應力為 y=MPa =32.9MPa0焊縫拉伸疲勞許用應力為 rl= =MPa =89.57MPa r=0.26860按K0查的-1=133MPa，取拉伸式 rl= =MPa =234.8MPa r=166MPa = =0.2130可見，在相同的循環(huán)工況下，應力循環(huán)特性是一致的。根據A6和Q235及帶孔板的應力集中等級W2，查的-1=122MPa。翼緣板拉伸疲勞許用應力為 rl= =MPa =219.5MPa maxrl若考慮垂直載荷與水平載荷同時作用，則計算應力要大些腹板受力較小，不再計算3.2.4 穩(wěn)定性整體穩(wěn)定 =2.393 (穩(wěn)定)局部穩(wěn)定翼緣板 （穩(wěn)定）腹板 故只需要對著主梁腹板位置設置四塊橫隔板，=6mm3.2.5 端梁拼接端梁在中央截面1-1采用拼接板精制螺栓連接，翼緣用雙面拼接板8mm420mm440mm及8mm350mm440mm,腹板用單面拼接板8mm440mm860mm，精制螺栓選取M20mm,拼接構造及螺栓布置如圖14所示。 圖3-12 端梁拼接構造 （1）內力及分配滿載小車在跨端時，求的截面1-1的內力為 Mx1=597409Nm,剪力Fv1=0 My1=26966Nm,FH1=21130.5N Nd=25133N端梁的截面慣性矩為 Ix=2.32149109mm4 Iy=5.9251108mm4腹板對x和y軸的總慣性矩為 Ifx=9.2108108mm4 Ify=4.7894108mm4翼緣對x和y軸的總慣性矩為 Iyx=1.400408109mm4 Iyy=1.1358108mm4彎矩分配Mx1:腹板 Mfx=Mx1=237029.4Nm翼緣 Myx=Mx1=360379.6NmMy1:腹板 Mfy=My1=21797Nm 翼緣 Myy=My1=5169Nm水平剪切力分配剪力由上、下翼緣板平均承受，一塊翼緣板所受剪切力為 F1=0.5FH1=10565N軸力分配軸力按截面積分配一塊翼緣板受軸力 Ny=4176N一塊腹板受軸力 Nf=8390.3NA=21184mm2,Ay=3520mm2,Af=7072mm2（2）翼緣拼接計算 由Myx產生的翼緣軸力為 N”y=404013N一塊翼緣板總軸力為 Ny=Ny+N”y=408189N拼接縫一邊翼緣板上有8個螺栓，一個螺栓受力（剪切力）為 PyN=N =50123.6NMyy由上下翼緣板平均承受，一塊翼緣板的水平彎矩為 My=2585Nm拼接縫一邊翼緣板上螺栓的布置尺寸為=3，可按窄式連接計算x1=150mm,xi2=4(502+1502)mm2=100000mm2翼緣板角點螺栓的最大內力為 Py1=N=3877.5N角點螺栓順梁軸的內力和為 FN=PyN+Py1=(51023.6+3877.5)N=54901N水平剪切力F1由焊接縫一邊翼緣上的螺栓平均承受，一個螺栓的受力為 Fs=1320.6 *學院畢業(yè)設計任務書系 別：機械工程系專 業(yè)：機械設計制造及其自動化學 生 姓 名：學 號：設計題目：橋式起重機橋架結構設計起 迄 日 期:設計地點:指 導 教 師:系 主 任:發(fā)任務書日期: 年 月 日畢 業(yè) 設 計 任 務 書1畢業(yè)設計課題的任務和要求： 熟悉橋式起重機的結構和工作原理，完成某型號橋式起重機的結構設計計算，并利用Solidwork建立其關鍵件的三維模型和工程圖，相關參數依據起重機設計手冊。 2畢業(yè)設計課題的具體工作內容（包括原始數據、技術要求、工作要求等）：1 掌握Solidworks的使用技術；2 熟悉橋式起重機的工作原理；3 完成某型號橋式起重機的結構設計計算；4 完成橋式起重機的的三維建模，繪制關鍵零部件的二維工程圖； 5 撰寫設計說明書： (1)設計合理，語句通順，格式規(guī)范，圖表正確，表述清晰； (2)打印成冊。6 外文翻譯。畢 業(yè) 設 計 任 務 書3對畢業(yè)設計課題成果的要求包括畢業(yè)設計、圖紙、實物樣品等)：1 畢業(yè)設計說明書一本；2 圖紙一套。4畢業(yè)設計課題工作進度計劃：起 迄 日 期工 作 內 容2013年2月25日 3 月 23 日3月 24日 5月 9 日5月 10日 5月25日5月 25日 6月10日學習相關軟件，查閱資料，撰寫開題報告；熟悉開發(fā)環(huán)境，詳細設計；撰寫論文；論文答辯。學生所在系審查意見：系主任： 年 月 日 *學院*屆畢業(yè)設計中英文翻譯The Use and History of CraneEvery time we see a crane in action we remains without words, these machines are sometimes really huge, taking up tons of material hundreds of meters in height. We watch with amazement and a bit of terror, thinking about what would happen if the load comes off or if the movement of the crane was wrong. It is a really fascinating system, surprising both adults and children. These are especially tower cranes, but in reality there are plenty of types and they are in use for centuries. The cranes are formed by one or more machines used to create a mechanical advantage and thus move large loads. Cranes are equipped with a winder, a wire rope or chain and sheaves that can be used both to lift and lower materials and to move them horizontally. It uses one or more simple machines to create mechanical advantage and thus move loads beyond the normal capability of a human. Cranes are commonly employed in the transport industry for the loading and unloading of freight, in the construction industry for the movement of materials and in the manufacturing industry for the assembling of heavy equipment.1. OverviewThe first construction cranes were invented by the Ancient Greeks and were powered by men or beasts of burden, such as donkeys. These cranes were used for the construction of tall buildings. Larger cranes were later developed, employing the use of human treadwheels, permitting the lifting of heavier weights. In the High Middle Ages, harbor cranes were introduced to load and unload ships and assist with their construction - some were built into stone towers for extra strength and stability. The earliest cranes were constructed from wood, but cast iron and steel took over with the coming of the Industrial Revolution.For many centuries, power was supplied by the physical exertion of men or animals, although hoists in watermills and windmills could be driven by the harnessed natural power. The first mechanical power was provided by steam engines, the earliest steam crane being introduced in the 18th or 19th century, with many remaining in use well into the late 20th century. Modern cranes usually use internal combustion engines or electric motors and hydraulic systems to provide a much greater lifting capability than was previously possible, although manual cranes are still utilized where the provision of power would be uneconomic.2. HistoryAncient GreeceThe crane for lifting heavy loads was invented by the Ancient Greeks in the late 6th century BC. The archaeological record shows that no later than c.515 BC distinctive cuttings for both lifting tongs and lewis irons begin to appear on stone blocks of Greek temples. Since these holes point at the use of a lifting device, and since they are to be found either above the center of gravity of the block, or in pairs equidistant from a point over the center of gravity，they are regarded by archaeologists as the positive evidence required for the existence of the crane.The introduction of the winch and pulley hoist soon lead to a widespread replacement of ramps as the main means of vertical motion. For the next two hundred years, Greek building sites witnessed a sharp drop in the weightshandled, as the new lifting technique made the use of several smaller stones more practical than of fewer larger ones. In contrast to the archaic period with its tendency to ever-increasing block sizes, Greek temples of the classical age like the Parthenon invariably featured stone blocks weighing less than 15-20 tons. Also, the practice of erecting large monolithic columns was practically abandoned in favor of using several column drums.Although the exact circumstances of the shift from the ramp to the crane technology remain unclear, it has been argued that the volatile social and political conditions of Greece were more suitable to the employment of small, professional construction teams than of large bodies of unskilled labor, making the crane more preferable to the Greek polis than the more labor-intensive ramp which had been the norm in the autocratic societies of Egypt or Assyria.The first unequivocal literary evidence for the existence of the compound pulley system appears in the Mechanical Problems (Mech. 18， 853a32-853bl3) attributed to Aristotle (384-322 BC), but perhaps composed at a slightly later date. Around the same time, block sizes at Greek temples began to match their archaic predecessors again, indicating that the more sophisticated compound pulley must have found its way to Greek construction sites by then.Ancient RomeThe heyday of the crane in ancient limes came during the Roman Empire, when construction activity soared and buildings reached enormous dimensions. The Romans adopted the Greek crane and developed it further. We are relatively well informed about their lifting techniques.The simplest Roman crane，the Trispastos, consisted of a single-beam jib, a winch, a rope, and a block containing three pulleys. Having thus a mechanical advantage of 3:1, it has been calculated that a single man working the winch could raise 150 kg (3 pulleys x 50 kg = 150), assuming that 50 kg represent the maximum effort a man can exert over a longer time period. Heavier crane types featured five pulleys (Pentaspastos) or, in case of the largest one, a set of three by five pulleys (Polyspastos) and came with two, three or four masts, depending on the maximum load. The Polyspastos, when worked by four men at both sides of the winch，could already lift 3000 kg (3 ropes x 5 pulleys x 4 men x 50 kg = 30(H) kg). In case the winch was replaced by a treadwheel, the maximum load even doubled to 6000 kg at only half the crew, since the treadwheel possesses a much bigger mechanical advantage due to its larger diameter. This meant that, in comparison to the construction of the Egyptian Pyramids, where about 50 men were needed to move a 2.5 ton stone block up the ramp (50 kg per person), the lifting capability of the Roman Polyspastos proved to be 60 times higher (3000 kg per person).However, numerous extant Roman buildings which feature much heavier stone blocks than those handled by the Polyspastos indicate that the overall lifting capability of the Romans went far beyond that of any single crane. At the temple of Jupiter at Baalbek, for instance, the architrave blocks weigh up to 60 tons each，and one corner cornice block even over 100 tons, all of them raised to a height of about 19 m. In Rome, the capital block of Trajans Column weighs 53.3 tons, which had to be lifted to a height of about 34 m (see construction of TrajarTs Column).Middle AgesDuring the High Middle Ages, the treadwheel crane was reintroduced on a large scale after the technology had fallen into disuse in western Europe with the demise of the Western Roman Empire. The earliest reference to a treadwheel (magna rota) reappears in archival literature in France about 1225, followed by an illuminated depiction in a manuscript of probably also French origin dating to 1240. In navigation, the earliest uses of harbor cranes are documented for Utrecht in 1244，Antwerp in 1263，Brugge in 1288 and Hamburg in 1291, while in England the treadwheel is not recorded before 1331.Generally, vertical transport could be done more safely and inexpensively by cranes than by customary methods. Typical areas of application were harbors, mines, and, in particular, building sites where the treadwheel crane played a pivotal role in the construction of the lofty Gothic cathedrals. Nevertheless, both archival and pictorial sources of the time suggest that newly introduced machines like treadwheels or wheelbarrows did not completely replace more labor-intensive methods like ladders, hods and handbarrows. Rather, old and new machinery continued to coexist on medieval construction sites and harbors.Apart from treadwheels, medieval depictions also show cranes to be powered manually by windlasses with radiating spokes, cranks and by the 15th century also by windlasses shaped like a ships wheel. To smooth out irregularities of impulse and get over dead-spots in the lifting process flywheels are known to be in use as early as 1123.The exact process by which the treadwheel crane was reintroduced is not recorded, although its return to construction sites has undoubtedly to be viewed in close connection with the simultaneous rise of Gothic architecture. The reappearance of the treadwheel crane may have resulted from a technological development of the windlass from which the treadwheel structurally and mechanically evolved. Alternatively, the medieval treadwheel may represent a deliberate reinvention of its Roman counterpart drawn from Vitruvius De architectura which was available in many monastic libraries. Its reintroduction may have been inspired，as well，by the observation of the labor-saving qualities of the waterwheel with which early treadwheels shared many structural similarities.Structure and placementThe medieval treadwheel was a large wooden wheel turning around a central shaft with a treadway wide enough for two workers walking side by side. While the earlier compass-arm wheel had spokes directly driven into the central shaft，the more advanced clasp-arnV type featured arms arranged as chords to the wheel rim, giving the possibility of using a thinner shaft and providing thus a greater mechanical advantage.Contrary to a popularly held belief, cranes on medieval building sites were neither placed on the extremely lightweight scaffolding used at the time nor on the thin walls of the Gothic churches which were incapable of supporting the weight of both hoisting machine and load. Rather, cranes were placed in the initial stages of construction on the ground，often within the building. When a new floor was completed, and massive tie beams of the roof connected the walls, the crane was dismantled and reassembled on the roof beams from where it was moved from bay to bay during construction of the vaults. Thus, the crane grew and wandered with the building with the result that today all extant construction cranes in England are found in church towers above the vaulting and below the roof，where they remained after building construction for bringing material for repairs aloft.Harbor usageAccording to the present state of knowledge” unknown in antiquity, stationary harbor cranes are considered a new development of the Middle Ages. The typical harbor crane was a pivoting structure equipped with double treadwheels. These cranes were placed docksides for the loading and unloading of cargo where they replaced or complemented older lifting methods like see-saws, winches and yards.Two different types of harbor cranes can be identified with a varying geographical distribution: While gantry cranes which pivoted on a central vertical axle were commonly found at the Flemish and Dutch coastside, German sea and inland harbors typically featured tower cranes where the windlass and treadwheels were situated in a solid tower with only jib arm and roof rotating. Interestingly, dockside cranes were not adopted in the Mediterranean region and the highly developed Italian ports where authorities continued to rely on the more labor-intensive method of unloading goods by ramps beyond the Middle Ages.Unlike construction cranes where the work speed was determined by the relatively slow progress of the masons, harbor cranes usually featured double treadwheels to speed up loading. The two treadwheels whose diameter is estimated to be 4 m or larger were attached to each side of the axle and rotated together. Today, according to one survey, fifteen treadwheel harbor cranes from pre-industrial times are still extant throughout Europe.28 Beside these stationary cranes, floating cranes which could be flexibly deployed in the whole port basin came into use by the 14th century. RenaissanceMechanical principlesThere are two major considerations in the design of cranes. The first is that the crane must be able to lift a load of a specified weight and the second is that the crane must remain stable and not topple over when the load is lifted and moved to another location.Lifting capacityCranes illustrate the use of one or more simple machines to create mechanical advantage.The lever. A balance crane contains a horizontal beam (the lever) pivoted about a point called the fulcrum. The principle of the lever allows a heavy load attached to the shorter end of the beam to be lifted by a smaller force applied in the opposite direction to the longer end of the beam. The ratio of the loads weight to the applied force is equal to the ratio of the lengths of the longer arm and the shorter ami, and is called the mechanical advantage.The pulley. A jib crane contains a tilted strut (the jib) that supports a fixed pulley block. Cables are wrapped multiple times round the fixed block and round another block attached to the load. When the free end of the cable is pulled by hand or by a winding machine, the pulley system delivers a force to the load that is equal to the applied force multiplied by the number of lengths of cable passing between the two blocks. Thisnumber is the mechanical advantage.The hydraulic cylinder. This can be used directly to lift the load orindirectly to move the jib or beam that carries another lifting device.Cranes，like all machines, obey the principle of conservation of energy. This means that the energy delivered to the load cannot exceed the energy put into the machine. For example, if a pulley system multiplies the applied force by ten, then the load moves only one tenth as far as the applied force. Since energy is proportional to force multiplied by distance, the output energy is kept roughly equal to the input energy (in practice slightly less, because some energy is lost to friction and other inefficiencies).StabilityFor stability, the sum of all moments about any point such as the base of the crane must equate to zero. In practice，the magnitude of load that is permitted to be lifted (called the rated load” in the US) is some value less than the load that will cause the crane to tip (providing a safety margin).Under US standards for mobile cranes, the stability-limited rated load for a crawler crane is 75% of the tipping load. The stability-limited rated load for a mobile crane supported on outriggers is 85% of the tipping load. These requirements, along with additional safety-related aspects of crane design, are established by the American Society of Mechanical Engineers in the volume ASME B30.5-2007 Mobile and Locomotive Cranes.Standards for cranes mounted on ships or offshore platforms are somewhat stricter because of the dynamic load on the crane due to vessel motion. Additionally, the stability of the vessel or platform must be considered.For stationary pedestal or kingpost mounted cranes, the moment created by the boom, jib，and load is resisted by the pedestal base or kingpost. Stress within the base must be less than the yield stress of the material or the cranewill fail.The kinds of crane MobileMain article: Mobile craneThe most basic type of mobile crane consists of a truss or telescopic boom mounted on a mobile platform - be it on road, rail or water.FixedExchanging mobility for the ability to carry greater loads and reach greater heights due to increased stability, these types of cranes are characterized that they, or at least their main structure does not move during the period of use. However，many can still be assembled and disassembled.3. Overhead CranesUseThe most common overhead crane use is in the steel industry. Every step of steel, until it leaves a factory as a finished product, the steel is handled by an overhead crane. Raw materials are poured into a furnace by crane, hot steel is stored for cooling by an overhead crane, the finished coils are lifted and loaded onto trucks and trains by overhead crane, and the fabricator or stamper uses an overhead crane to handle the steel in his factory. The automobile industry uses overhead cranes for handling of raw materials. Smaller workstation cranes handle lighter loads in a work-area, such as CNC mill or saw.HistoryAlton Shaw, of the Shaw Crane Company, is credited with the first overhead crane, in 1874. Alliance Machine, now defunct, holds an AISE citation for one of the earliest cranes as well. This crane was in service until approximately 1980，and is now in a museum in Birmingham, Alabama. Over the years important innovations, such as the Weston load brake (which is now rare) and the wire rope hoist (which is still popular)，have come and gone. The original hoist contained components mated together in what is now called the built-up style hoist. These built up hoists are used for heavy-duty applications such as steel coil handling and for users desiring long life and better durability. They also provide for easier maintenance. Now many hoists are package hoists, built as one unit in a single housing, generally designed for ten-year life or less.第 14頁 共 14頁起重機的用途與歷史每當我們看到一臺正在運作的起重機，我們都會驚訝不已，這些機器有時碩大無比，能把成噸的貨物提升到空中?？吹竭@些龐然大物的時 候我們心理都帶著一種驚愕，有時甚至是有一點恐懼的心情，我們會去想如果吊著著的東西掉下來了或者起重機吊錯了位置會發(fā)生什么樣恐怖的情形。起重機的確是一種令人著迷的機械系統(tǒng)，無論是成人或者是孩子無不為止驚嘆。起重機的種類五花八門，并且歷史悠久。起重機是用一個或者幾個簡單的機器來組成一個機械結構并用于運送那些人無法搬動的物品。一般來說，起重機由一個卷筒、一束金屬繩或是一條金屬鏈組成來同時提升、放置成者足水平移動貨物。起重機的.工作領域 一般處在需要裝卸貨物的運輸業(yè)、需要搬運建材的建筑業(yè)和需要組裝重型設備的制造業(yè)。1.概況第一臺具有機械結構的起重機是由古希臘人發(fā)明的，并且由人或者牲畜比如驢，作為動力源。這種起重機被用于建筑的建造。這種起重機后來發(fā)展成了采用人力踏板驅動的更人性的起重機，用來提升更重 的物料。中世紀時港口起重機被叫來裝卸船上的貨物，有的港口起重機 為求更大的起重重量和更好的穩(wěn)定性被造在了石塔里。最早的起重機是用木頭制造的，工業(yè)革命之后，鑄鐵和鋼材就代替了木頭用于制造起重機。盡管水磨機和風車都可以利用自然的能源來驅動，但是幾個世紀以來，起重機的動力源一直是人力或者畜力。第一臺真正釆用機械能量的起重機用的是蒸汽機，最早的蒸汽起重機出現于18到19世紀，有一些甚至到了 20世紀末仍能很好地使用。雖然由于能源的供應仍不可及， 到現在有一些人力起重機還在使用，但是現代的起重機一般采用的內燃機、電動馬達、液壓系統(tǒng)能為起重機提供比之前大得多的提升力。2.歷史2.1古希臘時期用來提升重型貨物的起重機是希臘人在公元前六世紀晚期發(fā)明的。 考古記錄顯示最早在公元前515年提升夾具和鐵制的吊楔開始出現在古希臘人石塊結構的神殿里。由干這些是起重設備的核心裝置、也由于他 們在石塊的重心的中央或者趟在離重心上一點距離相等的兩頭被發(fā)現，他們被考古學家認為是起重機當時就存在的確鑿證據。絞盤與滑輪的的引入導致了人類之前用斜坡來向高處運送貨物的方法被廣泛替代。在接下來的兩百年中，希臘的建筑都采了這樣新型的提升物料的技術，它利用了一些小型的石塊來來代替人塊的石頭，這樣更具實用性。與更早先的古希臘人神殿的建筑材料的尺寸不斷變得越來越大趨勢相比較，希臘古典廟宇比如帕臺農神廟的石塊重景都小于15- 20噸。而且，要把巨型的石柱豎立起來的作業(yè)使希臘人實際上更喜歡用好幾塊像鼓一樣的圓柱石塊堆疊而成。盡管確切何時從斜坡運輸進入起重機提升技術時代的時間還不是很淸楚。但是當時古希臘不穩(wěn)定的社會周勢、和政治情況使得建造神殿更適合雇傭小觀的、更加專業(yè)的建筑團隊而不是像埃及和亞述那樣大量使用的沒有技術的分動力。這樣的情況使得起重機更像希臘城邦發(fā)明 的而非釆用純究動力斜坡運送貨物的埃及或是亞述那樣的獨裁國家。文學上第一次的明確的記載滑輪組的復合系統(tǒng)是出現在亞里士多德的機械難題中，但清楚組成文字可能還要稍晚一些。與此同時，用于建造希臘神廟的石塊尺寸再一次開始趕上他們的古代前輩了，這標志著當 時更多的久經考驗的的滑輪組在希臘建筑史上找到了它們的一席之地。2.2古羅馬時期起重機械在古代的全盛時期卻足在古羅馬帝國展幵的。當時建筑物的數景激增，而且這些建筑都達到了巨型的尺寸。羅馬人采用了希臘人的起重機并將其發(fā)揚光大。多虧了那些維特獸程師們撰寫的相當冗長 的文獻和亞歷山大帝的蒼鷺的巢，我們才得以如此詳細地了解到了它們的其中技術。三餅滑車是古羅馬最簡單的一種起重機，它是由一個單梁吊臂、一個 絞盤、一條繩子和一個三個滑輪組成的滑輪組組成的。經計算，假設一個人用盡力氣能夠長時間地提起相當于重 50千克的物體那么通過這樣的起重機械他以提升約150千克的物體(3 個滑輪X50千克= 150千克）。更加重型的起重機就擁有五個滑輪（五餅 滑車），最大的起重機會在兩根、三根甚至是四根桅桿上面裝上三餅和 五餅的復合滑輪組（復滑車），這足由最大的負載載荷決定的。復滑車工作的時候兩邊需要4個人：兩邊各站兩個已經可以提起重約3000千克的 物體（3條繩子X5個滑輪X4個人X50千克= 3000千克）。如果用踏車來代替絞盤的話，最大的起重載荷可以在人工減半的情況下達到兩倍一 6000千克，因為踏車有更大的直徑能夠提供多個人的力矩。這意味著，和建造埃及金字塔時50個人才能通過斜坡搬動2.5噸的石塊（50 千克每人）的情況相比，羅馬的復滑車的提升能力把工作的效率提高60 倍（3000千克每人）。然而，大量現存的古羅馬建筑中那些石塊的重量比復滑車所能操作的負載耍重得多。這表明古羅馬人全面的起重的能力要遠遠大于任何簡單的起重機。以Baalbek的Jupiter神廟為例，那些楣梁的石塊每塊都重達60 噸以上，每個檐口的石塊甚至達到了 100噸以上，所有這些石料都被提 升到了 19m的半空中。在羅馬Trajan之柱的主要石塊重達53. 3噸，而這些石塊必須被提升到34m的高度。（見Trajian之柱）2.3中世紀時期在中世紀時，隨著西羅馬帝國的滅亡，歐洲的科技技術水平一落千丈。這時踏車式的起重機再次被大范圍地使用。最早的提到踏車式是大約1225年法國的一部檔案文學作品，它在一份手稿上也說明敘述了直到 1240年法國人的血統(tǒng)起源。在航海方面，最大的港口起重機是在1244 年的 Utrecht、1263 年的 Antwerp、1288 年的 Brugge 和 1291 年的 Hamburg, 而在英格蘭踏車式的起重機直到1331年才有所記錄。一般來說，釆用起重機來垂直運輸比傳統(tǒng)的方法更加的安全和經濟。典型的應用領域就包括港口、礦井。值得一提的是在哥特式人教堂的建 造過程中，踏車式的起重機起到了一個不可成缺的重要作用。但是，檔 案和圖畫都顯示了當時新引進的機械系統(tǒng)如踏車、獨輪手推車等卻沒有完全替代那些樓梯、木桶、手推車等依賴勞動力的生產方法。這樣，舊式的和新式的機械在繼續(xù)在中世紀的建筑和港口共存。除了踏車，中世紀的文獻中也記載了由手動驅動帶幅輪和曲柄的絞盤的起重機，在15 世紀時也是由卷揚機發(fā)展成為了類似船輪的系統(tǒng)。為了緩沖這些不規(guī)則的沖擊力和解決提升過程中的死點問題，調速輪最早在1123年開始投入使用。踏車式起覓機具體以何種方式再次被釆用的已經無從考證，盡管它多次被使用在建筑領域，被毋庸置疑地認為和哥特式建筑的崛起有相當密切的關系。踏車式起重機的再次出現可能導致了卷揚機的技術發(fā)展，因 為卷揚機在踏車式起重機的結構和機械方面都有所發(fā)展。中世紀的踏車可以看作是羅馬Vitruvius De 工程師設計品的一個精心改造品，它們可以在很多寺廟館藏中看到。3.結構與用途中世紀的踏車結構是由一個木輪