鋼坯火焰清理機(jī)中的翻板機(jī)構(gòu)設(shè)計(jì)[三維SW]【4張CAD圖紙】
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翻板裝置中各數(shù)據(jù)計(jì)算 一、雙臂曲柄搖桿式翻板機(jī)設(shè)計(jì)1.1概述翻板機(jī)是中厚板車間精整工段不可缺少的輔助設(shè)備之一。其作用是將鋼板翻轉(zhuǎn)180,用來檢查鋼板上、下表面的質(zhì)量。本次鋼坯火焰清理機(jī)設(shè)計(jì)中,對鋼板上、下兩表面進(jìn)行清理,采用的翻板機(jī)構(gòu)為雙臂曲柄搖桿式翻板機(jī)構(gòu)。雙臂曲柄搖桿式翻板機(jī)由電機(jī)、減速機(jī)、曲柄連桿機(jī)構(gòu)組成。電機(jī)、減速機(jī)提供低速大扭矩的動力,由兩個曲柄連桿機(jī)構(gòu)分別帶動翻板臂和接板臂的旋轉(zhuǎn),從而實(shí)現(xiàn)翻板的動作。1.2工作原理和結(jié)構(gòu)特點(diǎn)圖1.1為雙臂曲柄搖桿式翻板機(jī)的機(jī)構(gòu)示意簡圖。電機(jī)經(jīng)減速機(jī)減速后,由減速機(jī)的低速軸分別帶動兩套曲柄四連桿機(jī)構(gòu),兩個曲柄a1、a2有一定的角度位置差,兩搖桿軸上有若干個翻板臂和接板臂。低速軸帶動曲柄做逆時(shí)針轉(zhuǎn)動,曲柄a1帶動連桿b1,連桿b1帶動搖桿c1做逆時(shí)針轉(zhuǎn)動;同時(shí)曲柄a2帶動連桿b2,連桿b2帶動搖桿c2做順時(shí)針轉(zhuǎn)動。為了滿足空載啟動,在初始位置翻板臂(送料撥桿)先向下偏轉(zhuǎn)5,接板臂也位于水平面以下偏5,翻板臂逆時(shí)針旋轉(zhuǎn)托起鋼板直到與水平位置成85,與此同時(shí),接板臂(接料撥桿)由水平位置順時(shí)針旋轉(zhuǎn)處于與翻板臂平行和接近平行的位置。然后兩臂加持鋼板一起轉(zhuǎn)動,開始鋼板的交接(如圖2)。當(dāng)它們共同轉(zhuǎn)過10后,翻板臂開始返回到水平位置。此時(shí)接板臂也托起鋼板返回,當(dāng)處于水平位置時(shí),鋼板落到輥道上,完成180翻面。而此時(shí)接料臂仍繼續(xù)向下偏轉(zhuǎn)5,最后再回到水平位置。從而完成一次翻板,完成一次翻板的時(shí)間是21s。圖1.1 轉(zhuǎn)動角度初始位置圖 圖1.2 接送位置角度圖結(jié)構(gòu)特點(diǎn):1、 兩翻臂的擺動角度100,從水平線下5擺到過垂直位置5,當(dāng)減速器輸出軸的曲柄回轉(zhuǎn)360,通過兩連桿帶動兩搖桿在105來回?cái)[動一次,兩翻臂則在100來回?cái)[動一次,兩曲柄相位差22814,故主動翻臂以-5擺動托起鋼板到85時(shí),從動翻臂擺動100過垂直線5。2、 翻臂的擺動是由曲柄通過連桿、搖桿、撐桿在翻臂中部撐起而動,翻臂軸不承受翻板扭矩,可以做得較小,兩翻臂軸就可以靠的很近(因?yàn)樽畲箐摪搴?00mm,取600mm)。3、 翻轉(zhuǎn)鋼板時(shí)由于接送撥桿有10左右的平行移動過程,所以交接平穩(wěn),不產(chǎn)生沖擊4、 在翻臂上安裝自由轉(zhuǎn)動的小托輥,當(dāng)鋼板沒有到規(guī)定位置(翻臂止擋處)而翻板時(shí),當(dāng)翻臂稍成傾角,鋼板就會平穩(wěn)而輕快地滾移到位,避免了很大沖擊和噪聲的產(chǎn)生。1.3機(jī)構(gòu)尺寸確定1、兩套四桿機(jī)構(gòu)極位夾角的確定兩套四桿機(jī)構(gòu)用OA1B1C1和OA2B2C2表示(如圖1.3)圖1.3 兩套四桿機(jī)構(gòu)極位夾角圖因?yàn)殇撆鹘唤舆^程中,要平穩(wěn)可靠,兩翻轉(zhuǎn)臂加持鋼板需同時(shí)旋轉(zhuǎn),并基本保持同步旋轉(zhuǎn)。故兩套四桿機(jī)構(gòu)的極位夾角(如圖1.4)必須相同,并且當(dāng)其值為零時(shí),沒有機(jī)會運(yùn)動,同步性最優(yōu)。、即:1=2=0圖1.4 兩套連桿機(jī)構(gòu)的極位夾角圖二、機(jī)構(gòu)尺寸確定在設(shè)計(jì)中,由于場地等因素的限制,可預(yù)先確定L1、L2和h。即兩套四桿機(jī)構(gòu)的機(jī)架長度d1、d2。2.1第一套四桿機(jī)構(gòu)尺寸的確定 圖2.1 第一套四桿機(jī)構(gòu)極限位置圖預(yù)先確定搖桿長度c1,根據(jù)=0,機(jī)架長度d1及搖桿擺角可以作出圖2.1,從而求得其余桿件的尺寸。在圖5中,OB1=b1-a1,OB1=b1+a1,B1B1=OB1-OB1=2a1,a1,b1分別為曲柄和連桿長度。故a1= B1B1/2又因B1B1=2c1/sin(/2),所以a1=c1*sin(/2),設(shè)C1O長為d1,從圖5中可以求得d1=L12+H21/2 b1= d12-(c1*cos)2 取值L1=3000mm,H=500mm,C1=700mm, =105(在設(shè)計(jì)中,由于場地等因素的限制,可預(yù)先確定L1,L2和H,即兩套四桿機(jī)構(gòu)的機(jī)架長度d1和d2)故a1=c1*sin(/2)=555mm 連桿b1=L12+H2- (c1*cos)212 =9250000-181589.334=3011.4 d1= (L12+H2)12 =3041.42.2第二套四桿機(jī)構(gòu)尺寸的確定圖2.2 第二套四桿機(jī)構(gòu)極限位置圖按照確定第一套機(jī)構(gòu)尺寸同樣的方法,可方便的求得第二套機(jī)構(gòu)尺寸。預(yù)先確定C2=700mm,H1=H2=500mm。a2=c2sin=555mm d2= (L1+L2)2+H212=5024.9b2=d22-(c2cos)212=25250000-181589.312=5006.842.3曲柄存在條件及傳動角的驗(yàn)算當(dāng)兩套四桿機(jī)構(gòu)的尺寸確定以后,還要進(jìn)行曲柄存在條件及傳動角大小的驗(yàn)算。曲柄存在條件是:曲柄為最短桿;機(jī)構(gòu)中最短桿與最長桿之和小于或等于其余兩桿長度之和驗(yàn)算兩套機(jī)構(gòu)桿的尺寸:曲柄a1,a2、連桿b1,b2、搖桿c1,c2、連架桿d1,d2應(yīng)滿足下列條件:a1+d1c1+b1和a2+d2c2+b2 a1+d1=555+3041.4=3596.4c1+b1=700+3011.4+3711.4a1+d1 符合要求 a2+b2=555+5024.9=5579.9c2+d2=700+5006.8=5706.8a2+d2 符合要求傳動角的驗(yàn)算如下(見圖2.3)圖2.3 傳動角的極限大小圖7當(dāng)曲柄a轉(zhuǎn)到與連架桿g成一直線或重合的兩極限位置時(shí)傳動角u有最大值和最小值。 umax=cos-1b2+c2-(d+a)2/2bc umin=cos-1 b2+c2-(d-a)2/2bc若電動機(jī)力矩變化不大,為了提高效率,傳動角應(yīng)盡量在90附近一般umax150, umin30。代入第一套數(shù)據(jù)umax=143.2150、umin=36.8,umax=142.7150、umin=37.25。均滿足要求2.4 第三套機(jī)構(gòu)尺寸e的確定根據(jù)場地的條件限制,取定H2=2300mm,L4=400mm,f2=1200mm,(翻板臂整長為2400mm)當(dāng)手臂處于水平時(shí),支撐桿與翻臂垂直或接近垂直時(shí)受力最大,設(shè)定角F2E2D2為90。L3=L2/2-L4/2=800mm,f2-L2=D2O=400C2=(C2D2-D2O)1/2=(14002-4002)1/2=1341.67mme1=C2O+H2=3642搖桿擺角及板臂(以下簡稱撥桿)下偏角的選取原則根據(jù)翻板機(jī)的工作特性,為滿足兩撥桿在一定角度范圍內(nèi)(一般在85-95)基本上能同步旋轉(zhuǎn),除按上節(jié)介紹的方法設(shè)計(jì)外,還應(yīng)正確地選擇及,和不能隨意選取,事實(shí)上它們之間存在有某種聯(lián)系,現(xiàn)推導(dǎo)如下,如圖2.4圖2.4 搖臂的極限位置圖假設(shè)工藝要求兩撥桿在角度處開始交接鋼板,此時(shí)送料撥桿1所轉(zhuǎn)過的角度為A1=+2左側(cè)接料撥桿所轉(zhuǎn)過的角度為A2=-+由工作原理我們知道,當(dāng)兩撥桿開始鋼板交接時(shí),它們所轉(zhuǎn)過的角度相等。即:A1=A2由上面三式可得+2=-+由圖可知=-180-(-)整理以上式子,可知-2=90.1另外,為保證兩撥桿至少在85位置開始鋼板交接,即-952可以用1、2倆式來確定及的大小。三、整個曲柄連桿機(jī)構(gòu)的載荷計(jì)算3.1 e2載荷和大小計(jì)算為簡化計(jì)算,只考慮鋼板的荷載(鋼板重24噸),其它構(gòu)件的荷載忽略不計(jì),也不考慮加速度引起的動負(fù)荷。由于a1、b1、c1、d1、e1和a2、b2、c2、d2、e2是兩套一樣的連桿機(jī)構(gòu),算前面一套的數(shù)據(jù)就可以把另外一套的數(shù)據(jù)確定。除了b1、b2的根據(jù)布局不同選取的長度不同外,其它的數(shù)據(jù)都是一樣。3.1 翻轉(zhuǎn)臂是往下轉(zhuǎn)5脫離鋼板以后再通過e2給翻臂一個向上的力托起鋼板使其翻轉(zhuǎn)。由5到剛接觸鋼板的零界圖可以知道e2在垂直的往上頂?shù)臅r(shí)候所受到的荷載是最小的。如下圖: 圖3.1 局部受力和機(jī)座分布示意圖如圖3.1 按e2垂直翻轉(zhuǎn)臂和鋼板計(jì)算。連桿需要較高的屈服強(qiáng)度,綜合性能需求選45號鋼做連桿材料。GB/T699-1999標(biāo)準(zhǔn)規(guī)定的45鋼經(jīng)850正火、840淬火、600回火,達(dá)到的性能為屈服強(qiáng)度355MPa,= s/n,n為安全系數(shù),取5,則滿足要求。連架桿e2的載荷和大小計(jì)算過程如下:e2載荷:max=AF/= s/ns 取ns=5 , s=355MP。得到=71MP。F=24103Kg10N/kg=240000N,A=3380.28mm2,1d2/43380.28mm2d65.6mm,取80mm。3.2 搖桿d2、C2的載荷和大小計(jì)算:根據(jù)3.1圖所示可以知道兩機(jī)座之間的距離是2460mm,兩翻臂軸中心孔的距離是600mm。算出C2到G的距離:D2G=1200-(1230-300)=270mm根據(jù)圖上的受力分析可以知道搖桿C2D2在D2處的受力情況。利用三角形相似定理可得到連架桿作用在上面的力為24000N,垂直搖桿C2D2的力為F=2400010270140046285.71N。 一邊5套相同的C2D2,將力F除5得到單個力為9257.14N??古そ孛婺A縒t=D /16 T / Wt=FL / Wt =9257.141400(D /16)0.53555 D (9257.14140016)( * 35.5)=1856401.074mmD122.9mm ,取D為130mm。C2桿的計(jì)算:根據(jù)力矩守恒有F1*C2D2 = F2*C2B2 ,得到F2=2F1 ??古そ孛婺A縒t=D /16 T / Wt=FL / Wt 則有D31629257.1470035.53.141860230.88mm =D122.99mm。3.3 連架桿和搖臂直接的連接軸大小和載荷計(jì)算當(dāng)搖臂水平不動承受鋼板載荷時(shí),連架桿和搖臂直接的軸與搖桿d2與連架桿之間的軸是一樣的。5個搖臂受力分析得每個受力為24000105=48000N,取連桿軸長度為350mm,軸受到的最大剪應(yīng)力為=16T/D30.5s/5,得D3516FL/0.5s=516480003503.140.5355=2411411.14mm3D134.10mm3.4 連桿b與搖桿c之間的連接軸計(jì)算按上面受力分析得F2=29257.14N,軸還是取350mm長,則Wt=D /16 , T / Wt=FL / Wt,則有D31629257.1435035.53.14=930115.44mm3;D97.6mm。3.5連桿b的大小計(jì)算上面求得F2為29257.14N,受力分析得到F合為29257.141400270=95999.97N。max=AF/= s/ns 取ns=5 , s=355MP。得到=71MP。F合=95999.97N,A=1352.11mm2,1d2/41352.11mm2d41.5mm, 取100mm。3.6 曲柄a的大小和強(qiáng)度計(jì)算取曲柄長度為555mm,連桿機(jī)構(gòu)損耗率為0.8.由上面可以知道電動機(jī)輸出力矩為24000101.20.8=360000Nm,則曲柄的切線方向的力的大小為3600000.555N=648648.65N。則Wt=D /16 , T / Wt=FL / Wt =0.5s/5,則有D316648648.6555535.53.14=51673096.01mm3;D372.47mm。曲柄與連桿的連接軸取連接軸長為250mm,按上面受力分析得F=648648.65N,則Wt=D /16 , T / Wt=FL / Wt,則有D316648648.6525035.53.14=23276169.37mm3;D285.52mm。四. 電動機(jī)和減速器的選取 由前面講敘的翻臂翻轉(zhuǎn)一次再回到原來位置的要用21s,曲柄轉(zhuǎn)動一周也是t=21s。圓周長s=2r=23.140.555=3.4854m。曲柄切線方向的力為F=648648.65N,那電動機(jī)的輸出功率為P=FS/T=107657.1431w=107.66kw。選取電動機(jī)為YZR355M-10型號的額定功率為110Kw,轉(zhuǎn)速為581r/min。 曲柄21s內(nèi)完成一次循環(huán),一分鐘轉(zhuǎn)2.857圈,總傳動比i=5812.857204 將額定功率和傳動比告訴廠家可以定到符合規(guī)格的電動機(jī)和減速器。結(jié)論與展望本文對曲柄翻板機(jī)的一些關(guān)鍵數(shù)據(jù)進(jìn)行了計(jì)算,獲得了一些成果與結(jié)論。我們求出了翻版過程受力和四桿機(jī)構(gòu)中各個桿件的強(qiáng)度及大小,現(xiàn)已經(jīng)能夠熟練的操作SolidWorks制圖軟件。同時(shí)我們對機(jī)構(gòu)的尺寸確定、傳動角及各角度的驗(yàn)算、電動機(jī)的選取方法都有了一定的掌握。原本要通過比較繁瑣的單一的翻轉(zhuǎn)在這套機(jī)構(gòu)出現(xiàn)以后大大的改進(jìn)了生產(chǎn)流程,節(jié)約了時(shí)間和人力,也給工人們增強(qiáng)了安全保障。電機(jī)、減速機(jī)提供低速大扭矩的動力,由兩個曲柄連桿機(jī)構(gòu)分別帶動翻板臂和接板臂的旋轉(zhuǎn),由此帶動鋼板翻轉(zhuǎn)。翻轉(zhuǎn)工程中各桿件和搖臂的載荷、角度的變化迫切需要本文的出現(xiàn)。通過本文的研究分析得出的結(jié)論我們有理由相信:隨著我國制造業(yè)的不斷發(fā)展,不同類型的鋼板需求越來越大。這給鋼板生產(chǎn)家也帶來了技術(shù)更新的壓力,在結(jié)合生產(chǎn)經(jīng)驗(yàn)和各廠家場地的不同,曲柄四桿機(jī)構(gòu)翻板機(jī)將更加完善。在不久的將來曲柄連桿翻版機(jī)構(gòu)將會廣泛運(yùn)用于加工和檢測中,人工和維修性都會降低,生產(chǎn)效率將大大提高。參考文獻(xiàn)1秦大同機(jī)械傳動科學(xué)與技術(shù)北京:清華大學(xué)出版社,20032紀(jì)名鋼. 機(jī)械設(shè)計(jì).8版.北京:高等教育出版社,20063羅迎社.材料力學(xué).武漢:武漢理工大學(xué)出版社,20014吳宗澤.機(jī)械設(shè)計(jì)課程設(shè)計(jì)手冊.6版.北京:高等教育出版社,20065王勇勤.雙臂曲柄搖桿式翻板機(jī)機(jī)構(gòu)設(shè)計(jì)及改進(jìn).冶金設(shè)備94年第2期,20046 張錫玉 ,劉建波 ,湯武初. 曲柄搖桿式翻板機(jī)的仿真設(shè)計(jì)及改進(jìn). CFHITECHNOLOGY 09年第2期。20097胡堅(jiān).幾種中板翻轉(zhuǎn)機(jī)典型結(jié)構(gòu)的運(yùn)動分析.重鋼技術(shù).重鋼設(shè)計(jì)院,20088孫桓,葛文杰,陳作模.機(jī)械原理,第7版.高等教育出版社,20069 邵勝太,劉少陽. 翻板機(jī)曲柄連桿機(jī)構(gòu)的計(jì)算機(jī)設(shè)計(jì)及演示,河北冶金01年第3期.200110 于文妍. 翻板機(jī)構(gòu)的分析及其理論計(jì)算,內(nèi)蒙古科技與經(jīng)濟(jì)08年10月.2008致謝這次畢業(yè)設(shè)計(jì)即將完成的時(shí)候,其突然意識到四年的大學(xué)生涯即將畫上一個句號。當(dāng)我在外實(shí)習(xí)兩個月回來開始畢業(yè)設(shè)計(jì)時(shí),還不清楚留給我們將來可以還念的四年就要過去。在即將到來的工作崗位上所面臨的就是不同的生活方式,完全不同與之前的16年學(xué)生生涯。要是說原來的我們是學(xué)怎樣做人、怎樣做事、如何認(rèn)識和理解社會、如何學(xué)會感恩,那么,今后的日子里,我將真正成為一個有用的人,一個能與隊(duì)友合作或獨(dú)立完成任務(wù)的人,一個真正懂得世界、懂得感恩并真正付出的人。在這里首先要感謝我的指導(dǎo)老師胡自化老師,在本次設(shè)計(jì)開始到結(jié)尾過程中,一直跨度將近4個月時(shí)間,胡老師給我提供了寶貴的意見和資料。再者感謝我所有的組員,沒有他們的支持和鼓舞,我完成將更加困難。在組長提供的方案中選取曲柄翻轉(zhuǎn)機(jī)構(gòu)來作為本次的設(shè)計(jì)方向,這給我來將是種挑戰(zhàn)。我們組6個成員開始就到處查找資料,找到以后資源共享,這給本設(shè)計(jì)的完成提供了很大的幫助。很慶幸選擇胡老師和我其他的隊(duì)友一起走過大學(xué)的最后一段時(shí)光,我可以肯定這段時(shí)光將是我將來無比還念的大學(xué)生活。就是這段時(shí)光讓我認(rèn)識的團(tuán)隊(duì)合作的重要,學(xué)會了根據(jù)事實(shí)資料和理論知識來解決問題的方式,懂得了怎樣去查找資料,怎樣一步步的完成一個任務(wù)。這次設(shè)計(jì)真的讓我學(xué)到了很多。學(xué)無止境,無論每天往返于工廠和住所,還是奔走于圖書館和宿舍之間,作為一個職員或?qū)W生,無時(shí)無刻不在接受著新的知識、觀點(diǎn)、理念。即使是創(chuàng)造社會價(jià)值,也仍需不斷補(bǔ)給養(yǎng)分。于此,作為即將走出校園的人,我將銘記于心。最后,忠誠的希望每一個已經(jīng)出現(xiàn)在或是即將出現(xiàn)在我不同人生階段卻給我?guī)椭吞崾镜膸熼L、親友、同事們,能夠擁有美好幸福的生活狀態(tài),以及一顆熱衷于探索未知和真理的心,同時(shí)也是對自己未來生活的一種期冀。錄一:中文文獻(xiàn)字典一、聯(lián)動可能被定義為固體的,或鏈接,其中每一個環(huán)節(jié),是連接通過引腳連接(鉸鏈)或滑動關(guān)節(jié)至少有兩個人組合。為了滿足這一定義,必須形成一個聯(lián)動層出不窮,或關(guān)閉,或一個封閉的鏈條鏈系列。很明顯,有許多鏈接鏈的行為從為數(shù)不多的不同。這就提出了一個非常重要的問題,關(guān)于為運(yùn)動中的一臺機(jī)器傳輸給聯(lián)動的適用性。這是否適當(dāng)取決于鏈接的數(shù)量和接頭數(shù)量。 二、自由度。一個三桿機(jī)構(gòu)(含連在一起的三間酒吧)顯然是一個僵化的框架,沒有相對運(yùn)動之間的聯(lián)系是可能的。來描述一個四連桿機(jī)構(gòu),有必要才知道之間的任何連接兩個角度的聯(lián)系的相對位置。 (包括固定鏈接OQ的,在圖5c機(jī)制四個環(huán)節(jié),因此是一個四連桿機(jī)構(gòu)。)這種聯(lián)系是說,有一個自由度。兩個角度都必須在指定的五桿機(jī)構(gòu)的聯(lián)系的相對位置,它有兩個自由度 三、單自由度運(yùn)動的聯(lián)系,制約,也就是說,對所有的鏈接上所有的點(diǎn)都認(rèn)為是固定的,確定的其他鏈接路徑。路徑是最容易掌握的或假設(shè)上的路徑是必要的聯(lián)系是固定的,然后移動的方式與約束兼容其他環(huán)節(jié)的可視化。四、四桿機(jī)構(gòu)。當(dāng)一個約束聯(lián)系的成員之一,是固定的,聯(lián)動機(jī)制,執(zhí)行變成了機(jī)器中的一個有用的機(jī)械功能的能力。在針腳連接聯(lián)系的輸入(驅(qū)動器)和輸出(跟隨者)鏈接通常樞連接到固定的聯(lián)系;連接鏈路(耦合器)通常不投入,也沒有輸出。由于任何一個鏈接可以是固定的,如果鏈接的不同長度,四個機(jī)制,用不同的輸入輸出關(guān)系,每一個都可以得到以四桿機(jī)構(gòu)。這四個機(jī)制是說是基本的聯(lián)動反轉(zhuǎn)。五、當(dāng)最短的鏈接圖11(上)是固定的,鏈接B和D可以完成革命。這就是所謂的拖鏈接機(jī)制。如果曲柄在一個恒定速度b旋轉(zhuǎn),曲軸D將在同一方向旋轉(zhuǎn)的速度也不同。通過自身或與其他機(jī)制系列,拉桿可以提供有用的運(yùn)動效果。在圖中,曲柄B是司機(jī),在一個統(tǒng)一的旋轉(zhuǎn)速度逆時(shí)針;曲柄D掃過的角度,這是只有50度掃描。這意味著,曲柄d將曲柄移動速度比b當(dāng)移動從B到B和比掃過的角度,這是只有50度掃描。這意味著,曲柄d將曲柄移動速度比b當(dāng)移動從B到B和比B更快速移動時(shí)來自B到B如果曲柄D組附加到一個沙在包裝機(jī)英尺,例如,其議案,這與一些升油墨的比例幾乎是停頓或停留,緩慢的部分可利用的,必須在一個緩慢的速度進(jìn)行執(zhí)行操作。 六、四桿機(jī)構(gòu)第二反演得到利用最短的鏈接作為司機(jī)。如圖(下),連一個可以顯示完整的革命,而對面的鏈接,這可能是為B,C或D,只能通過振蕩角。這就是所謂的曲柄搖桿機(jī)構(gòu),它是產(chǎn)生振蕩運(yùn)動有快速回報(bào)的行動裝置,結(jié)合有用的結(jié)果的事實(shí),對于逆時(shí)針旋轉(zhuǎn)的,振蕩的C從B到B的對應(yīng)角1,而從Bto乙振蕩對應(yīng)angle2。由于曲軸在一個恒定的速度旋轉(zhuǎn),1較大than2,搖臂將需要更長的時(shí)間由右擺動比其他的方式離開了。機(jī)器上做有益的工作只有在活躍的成員是在一個方向移動,快速回裝置的成員迅速返回其初始位置。七、在極端的立場所示,虛線在圖(下),曲柄和連桿一個鏈路B一字排開(共線),如果C組的搖桿驅(qū)動程序,意味著將要進(jìn)行的追隨者提供鏈接過去這些死的立場。在腳踏式磨石腳踏板連接,連接C和砂輪軸連接答磨刀石的角動量是利用過去的死進(jìn)行位置的鏈接。八、在四桿機(jī)構(gòu),最短的鏈接是第三反演耦合器,以及其他運(yùn)動的聯(lián)系只能振蕩。這就是所謂的雙搖桿機(jī)構(gòu)。九、機(jī)構(gòu)綜合。圖形和分析方法,可以很容易地確定聘用的位移,速度,以及在一個聯(lián)動機(jī)制的聯(lián)系加速。設(shè)計(jì),或綜合的聯(lián)系,以滿足特定的要求是要困難得多。沒有設(shè)計(jì)一個拖放鏈接機(jī)制,以滿足輸入與輸出關(guān)系給予頻譜已知的方法。認(rèn)為做的最好的表現(xiàn)是調(diào)查一個特定的配置所選號碼的特點(diǎn),并挑選了最佳。十、在曲柄搖桿機(jī)構(gòu)的設(shè)計(jì)人員可以控制的搖桿和振蕩,角度在一定程度上的快速回報(bào)率。曲柄搖桿位移,速度,和加速度不能關(guān)聯(lián)十一、如果在一個四桿機(jī)構(gòu)的曲柄,總要在相同或旋轉(zhuǎn)方向相反,如果他們輪換限于大大低于180度,它可能會關(guān)聯(lián)曲柄在三,四輪換,五,或即使是大量的職位。這兩種方法的分析和圖形制作提供的相關(guān)性十二、圖12(左)顯示了函數(shù)發(fā)生器,相關(guān)的曲柄旋轉(zhuǎn)b在與旋轉(zhuǎn)60度以上D系列曲軸70度的范圍。這樣的相關(guān)關(guān)系,以滿足與X為Y = X2的不同從1到6和Y從1到36。 b的曲柄轉(zhuǎn)動的機(jī)械模擬X的,而旋轉(zhuǎn)曲柄D是Y的模擬X和Y之間的關(guān)系是準(zhǔn)確的在X= 1.19,2.54,4.46,和5.81;在它是錯誤的,但這個錯誤已經(jīng)被最小化的其他職位上述精確點(diǎn)多的間距。十三、函數(shù)發(fā)生器不是通常用來表示兩個功能相關(guān)的變量,如X和Y在圖12(左)所示的規(guī)模通常不提供相應(yīng)的值,他們已被添加到帶出一個最重要特征函數(shù)發(fā)生器,即規(guī)模是統(tǒng)一的,也就是說,在平等的師畢業(yè)。這意味著,由于為70度,而Y范圍為35,每兩個度旋轉(zhuǎn)曲柄對應(yīng)一個Y的單位,如果D是用來操作響應(yīng)B信號從一個閥門,相應(yīng)的三維旋轉(zhuǎn)到一個給定的Y的變化是在同一個范圍內(nèi)的所有點(diǎn)。十四、曲柄滑塊倒置。當(dāng)在一個四桿機(jī)構(gòu)的引腳連接都是由一名滑動聯(lián)合取代,一個有用的一些機(jī)制,可從產(chǎn)生的聯(lián)系。在圖13(上)之間的聯(lián)系1和4是一個滑動的接縫,允許4座,在幻燈片中鏈接的插槽連接1。這將不作任何區(qū)別,運(yùn)動學(xué),如果鏈路是在一個4孔或槽滑動鏈接1。十五、如果鏈接圖13(上)1是固定的,由此產(chǎn)生的曲柄滑塊機(jī)構(gòu)如圖13(中心)。這是一個往復(fù)引擎機(jī)制。該塊4代表活塞;鏈接1所示,陰影,是塊,它包含在A和汽缸的曲軸軸承;鏈接2是曲軸與連桿連接3。偏軸軸承是在B點(diǎn),在三腕銷軸承活塞的行程兩次AB公司,扔的曲柄。十六、曲柄滑塊機(jī)構(gòu)提供的手段轉(zhuǎn)換成曲軸的,或在一臺泵曲軸的旋轉(zhuǎn)運(yùn)動,旋轉(zhuǎn)運(yùn)動的活塞的運(yùn)動用在往復(fù)式發(fā)動機(jī)活塞成一個移動式的議案。在圖13(中心),當(dāng)B在位置B時(shí),會干擾連桿曲柄如果兩個人在同一平面上。這個問題解決了發(fā)動機(jī)和水泵來抵消從曲軸軸承曲柄銷軸承。通過使用一個地方的偏心和連桿機(jī)構(gòu)曲柄,沒有補(bǔ)償是必要的和非常小的拋出可以得到。十七、在圖13(下)在B點(diǎn)的偏軸軸承已成為一個巨大的圓形磁盤在A無所不能帶有偏心或扔AB型。連桿偏心桿,已成為一個帶的環(huán)繞和偏心幻燈片。在中部和底部圖圖13運(yùn)動學(xué)等效的機(jī)制。通過固定鏈接2,3,4而不是鏈接1,在圖13個連鎖有其他倒(上)獲得。十八、空間聯(lián)系。所考慮的聯(lián)系,到目前為止已全部平面,也就是說,它們的運(yùn)動一直局限在單一的平面或平行平面和軸平行,他們就可以了??臻g之間的聯(lián)系在三個層面,用于非平行軸之間傳遞運(yùn)動。雖然一些使用多年的著名空間聯(lián)動機(jī)制是特殊形式的聯(lián)系,但直到20世紀(jì)50年代的約kinematicians發(fā)展成為嚴(yán)重的描述,分析和綜合這些聯(lián)系程序感興趣。雖然在這一領(lǐng)域取得了一些進(jìn)展,許多問題仍未解決。十九、而一個平面連桿,或許可以用一個二維繪圖和分析,并與平面的幾何結(jié)構(gòu)合成的,這不是一個空間的聯(lián)系成為可能。至少有兩種觀點(diǎn)都是需要定義在三維空間的鏈接和其他方面復(fù)雜的速度和加速度分析。因此,空間聯(lián)系的分析涉及到高等數(shù)學(xué)的使用。二十、在平面上的聯(lián)系,只有兩種類型的連接器或接縫,即針或關(guān)節(jié)鉸鏈和滑動接頭(crossheads)。由于需要2個元素,使聯(lián)合,kinematicians稱之為運(yùn)動“對?!耙虼耍会樎?lián)合是一個旋轉(zhuǎn),或把對和一個滑動的接縫,是一個移動副。在空間上的聯(lián)系還有另外一些對,即一對圓筒,它允許兩個相對平移和旋轉(zhuǎn),螺旋對(螺絲和螺母),以及球形對(球窩關(guān)節(jié))。附錄1:英文文獻(xiàn)Linkages(連桿機(jī)構(gòu))1 A linkage may be defined as an assemblage of solid bodies, or links, in which each link is connected to at least two others by pin connections (hinges) or sliding joints. To satisfy this definition, a linkage must form an endless, or closed, chain or a series of closed chains. It is obvious that a chain with many links will behave differently from one with few. This raises the vitally important question regarding the suitability of a given linkage for the transmission of motion in a machine. This suitability depends on the number of links and the number of joints.2 Degrees of freedom. A three-bar linkage (containing three bars linked together) is obviously a rigid frame; no relative motion between the links is possible. To describe the relative positions of the links in a four-bar linkage it is necessary only to know the angle between any two of the links. (Including the fixed link OQ, the mechanism in Figure 5C has four links and is thus a four-bar linkage.) This linkage is said to have one degree of freedom. Two angles are required to specify the relative positions of the links in a five-bar linkage; it has two degrees of freedom.3 Linkages with one degree of freedom have constrained motion; i.e., all points on all of the links have paths on the other links that are fixed and determinate. The paths are most easily obtained or visualized by assuming that the link on which the paths are required is fixed, and then moving the other links in a manner compatible with the constraints.4 Four-bar mechanisms. When one of the members of a constrained linkage is fixed, the linkage becomes a mechanism capable of performing a useful mechanical function in a machine. On pin-connected linkages the input (driver) and output (follower) links are usually pivotally connected to the fixed link; the connecting links (couplers) are usually neither inputs nor outputs. Since any of the links can be fixed, if the links are of different lengths, four mechanisms, each with a different input-output relationship, can be obtained with a four-bar linkage. These four mechanisms are said to be inversions of the basic linkage.5 When the shortest link a in Figure 11 (top) is fixed, links b and d can make complete revolutions. This is known as a drag-link mechanism. If crank b rotates at a constant speed, the crank d will rotate in the same direction at a varying speed. By itself, or in series with other mechanisms, the drag link can provide useful kinematic effects. In the figure, crank b is the driver, rotating counterclockwise at a uniform rate; crank d is the follower. Both cranks make a complete revolution in the same time, but while b sweeps out the angle , which is 150 degrees the follower d sweeps out the angle , which is only 50 degrees. This means that crank d will move more slowly than crank b when moving from B to B and more quickly than b when moving from B to B. If crank d were attached to a sha ft in a packaging machine, for example, the slow part of its motion, which with some link proportions is almost a pause or a dwell, could be utilized for performing operations that must be done at a slow speed. 6 The second inversion of the four-bar mechanism is obtained by using the shortest link a as the driver. As shown in Figure (bottom), link a can make complete revolutions while the opposite link, which may be either b, c, or d, can only oscillate through the angle . This is called the crank-rocker mechanism; it is a useful device for producing oscillatory motion combined with a quick-return action that results from the fact that for counter-clockwise rotation of a, the oscillation of c from B to B corresponds with angle 1 , while oscillation from Bto B corresponds with angle2 . Since crank a rotates at a constant speed and 1 is greater than2 , the rocker will take longer to swing from right to left than the other way. On machines that do useful work only when the active members are moving in one direction, quick-return devices return the members quickly to their initial position.7 In the extreme positions, shown dotted in Figure (bottom), the crank a and the coupler link b are lined up (collinear), and if the rocker c were the driver, means would have to be provided to carry the follower link a past these dead positions. On foot-operated grindstones the foot pedal is attached to link c and the grindstone shaft to link a. The angular momentum of the grindstone is utilized to carry the links past the dead positions.8 On the third inversion of the four-bar mechanism, the shortest link a is the coupler; and the other moving links can only oscillate. This is called the double-rocker mechanism.9 Linkage synthesis. Graphical and analytical methods can be readily employed for determining the displacement, velocity, and acceleration of the links in a linkage mechanism. The design, or synthesis, of linkages to satisfy specific requirements is much more difficult. There is no known method for designing a drag-link mechanism to satisfy a given spectrum of input-output relationships. The best that can be done is to survey the performance characteristics of a selected number of specific configurations and pick the optimum.10 On the crank-rocker mechanism the designer can control the angle of oscillation of the rocker and, to a degree, the quick-return ratio. The crank and rocker displacements, velocities, and accelerations cannot be correlated.11 If the cranks in a four-bar mechanism always rotate in the same or in opposite directions, and if their rotations are limited to considerably less than 180 degrees, it may be possible to correlate the crank rotations in three, four, five, or even a larger number of positions. Both analytic and graphic methods are available for making the correlations.12 Figure 12 (left) shows a function generator that correlates the rotation of crank b over a 60-degree range with the rotation of crank d over a 70-degree range. The correlation is such as to satisfy the relationship Y=X2, with X varying from 1 to 6 and Y from 1 to 36. The rotation of crank b is the mechanical analogue of X, while the rotation of crank d is the analogue of Y. The relation between X and Y is accurate at X=1.19, 2.54, 4.46, and 5.81; at other positions it is in error, but the error has been minimized by the odd spacing of the above precision points. 13 A function generator is not ordinarily used to indicate corresponding values of two functionally related variables such as X and Y. The scales shown in Figure 12 (left) are not usually provided; they have been added to bring out the most important feature of a function generator, namely, that the scales are uniform; i.e., graduated in equal divisions. This means that, since is 70 degrees and the range of Y is 35, each two-degree rotation of crank d corresponds with one unit of Y, and if d is used to operate a valve in response to a signal from b, the rotation of d corresponding to a given change in Y is the same at all points in the range.14 Slider-crank inversions. When one of the pin connections in a four-bar linkage is replaced by a sliding joint, a number of useful mechanisms can be obtained from the resulting linkage. In Figure 13 (top) the connection between links 1 and 4 is a sliding joint that permits block 4 to slide in the slot in link 1. It would make no difference, kinematically, if link 4 were sliding in a hole or slot in link 1.15 If link 1 in Figure 13 (top) is fixed, the resulting slider-crank mechanism is shown in Figure 13 (center). This is the mechanism of a reciprocating engine. The block 4 represents the piston; link 1, shown shaded, is the block that contains the crankshaft bearing at A and the cylinder; link 2 is the crankshaft and link 3 the connecting rod. The crankpin bearing is at B, the wrist pin bearing at C. The stroke of the piston is twice AB, the throw of the crank.16 The slider-crank mechanism provides means for converting the translatory motion of the pistons in a reciprocating engine into rotary motion of the crankshaft, or the rotary motion of the crankshaft in a pump into a translatory motion of the pistons. In Figure 13 (center), when B is in position B, the connecting rod would interfere with the crank if both were in the same plane. This problem is solved in engines and pumps by offsetting the crankpin bearing from the crankshaft bearing. By using an eccentric-and-rod mechanism in place of a crank, no offsetting is necessary and very small throws can be obtained.17 In Figure 13 (bottom) the crankpin bearing at B has become a large circular disk pivoted at A with an eccentricity or throw AB. The connecting rod has become the eccentric rod with a strap that encircles and slides on the eccentric. The mechanisms in the center and bottom drawings of Figure 13 are kinematically equivalent.By fixing links 2, 3, and 4 instead of link 1, there other inversions of the linkage in Figure 13 (top) are obtained. 18 Space linkages. All of the linkages considered so far have been planar; i.e., their motions have been confined to a single plane or to parallel planes, and the shafts they connect have been parallel. Space linkages operate in three dimensions and are used to transmit motion between nonparallel shafts. Al
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