3083 連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì)
3083 連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì),連桿,加工,工藝,關(guān)鍵,癥結(jié),樞紐,工序,工裝,設(shè)計(jì)
南京理工大學(xué)泰州科技學(xué)院畢業(yè)設(shè)計(jì)說明書摘要作 者 : 趙彧學(xué) 號:05010150系 部 : 機(jī)械工程系專 業(yè) : 機(jī)械工程及自動化題 目 : 連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì)1 緒論本設(shè)計(jì)是連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì),并在此基礎(chǔ)上選擇關(guān)鍵工序之一進(jìn)行專用夾具及加工用組合機(jī)床設(shè)計(jì)。因此需要研究和解決以下幾個問題:(1)連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì);(2)關(guān)鍵工序之一的專用夾具設(shè)計(jì);(3)關(guān)鍵工序之一的加工用組合機(jī)床設(shè)計(jì)。2 連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì)2.1 連桿合件加工工藝設(shè)計(jì)2.1.1 生產(chǎn)綱領(lǐng),生產(chǎn)類型生產(chǎn)綱領(lǐng)為 50000 件/年,屬大批量生產(chǎn)。大批量生產(chǎn),零件具有廣泛的互換性,少數(shù)裝配精度較高處,采用分組裝配法和調(diào)整法;毛坯廣泛采用金屬模機(jī)器造型,精度高,加工余量??;廣泛采用專用機(jī)床及自動機(jī)床;廣泛采用專用夾具,專用組合機(jī)床,專用刀具,專用量具或自動檢驗(yàn)裝置,靠調(diào)整法達(dá)到精度要求;生產(chǎn)率高。2.1.2 工藝分析(1)零件材料:QT450—10。球墨鑄鐵切削性能較差,宜采用高速鋼(較低切削參數(shù)下) 、硬質(zhì)合金鋼刀具(較高切削參數(shù)下)以降低成本。刀具幾何參數(shù)可根據(jù)不同刀具類型依據(jù)相關(guān)手冊查取;(2)零件的表面組成:兩端面,大小兩個通孔,螺紋、螺栓孔,鍵槽,倒角,連桿體、連桿蓋結(jié)合面;(3)主要表面分析:Φ20mm 的小頭孔表面、Φ81mm 的大頭孔表面為零件最重要的工作面;(4)主要技術(shù)要求:小頭孔精度要求為 IT7、粗糙度要求 Ra1.6μm,大頭孔精度要求為 IT6、粗糙度要求 Ra1.6μm,大小頭孔中心距為 mm。大小頭孔之一為1.085?零件上的重要基準(zhǔn),兩側(cè)端面也為重要基準(zhǔn);(5)零件總體特點(diǎn):連桿合件由連桿體和連桿蓋兩部分組成。2.1.3 定位基準(zhǔn)的選擇在連桿機(jī)械加工工藝過程中,加工小頭孔時,工序選用連桿的一側(cè)端面作為主要基準(zhǔn)。加工連桿蓋時,選用連桿蓋的一個指定的端面、連桿蓋上的大頭孔及連桿蓋側(cè)面作為基準(zhǔn)。加工連桿體時,選用連桿體的一個指定端面、連桿體小頭孔及連桿體側(cè)面作為基準(zhǔn)。加工大頭孔時,選用連桿體的一個指定端面、連桿體小頭孔及連桿側(cè)面作為基準(zhǔn)。這是由于:端面的面積大,定位比較穩(wěn)定;用連桿蓋上的孔定位可直接控制大小孔的中心距;連桿側(cè)面限制轉(zhuǎn)動。這樣就使各工序的定位基準(zhǔn)統(tǒng)一起來,減少定位誤差。2.1.4 工藝路線方案的確定制定工藝路線主要是確定加工方法和劃分加工階段。選擇加工方法應(yīng)以零件加工表面的技術(shù)條件(主要是加工面的尺寸精度、形狀精度、表面粗糙度)為依據(jù),并綜合考慮各個方面工藝因素的影響,一般是根據(jù)主要表面的技術(shù)條件先確定終加工方法,接著再確定一系列準(zhǔn)備工序的加工方法,然后再確定其他次要表面的加工方法;在各表面加工方法選定以后,就需進(jìn)一步考慮這些加工方法在工藝路線中的大致順序,以定位基準(zhǔn)面的加工為主線,妥善安排熱處理工序及其他輔助工序。本零件加工工藝路線如下:工序 I:制備毛坯工序 II:同時銑連桿大小頭孔兩側(cè)端面工序 III:鉆、擴(kuò)、鉸連桿小頭孔工序 IV:分離連桿體和連桿蓋工序 V:銑連桿體結(jié)合面工序 VI:銑連桿蓋結(jié)合面工序 VII:加工連桿體的螺紋工序 VIII:加工連桿蓋的螺栓孔工序 IX:人工裝配連桿體和連桿蓋工序 X:粗鏜、半精鏜大頭孔工序 XI:精鏜大頭孔及大頭孔內(nèi)鍵槽工序 XII:鏜削小頭孔內(nèi)槽工序 XIII:銑小頭孔 R67mm 的槽工序 XIV:倒角,檢驗(yàn)2.1.5 工藝裝備的確定工藝裝備如表 1 工藝裝備表表 1 工藝裝備表工序號工序內(nèi)容 機(jī)床 夾具 刀具 量具I 制備毛坯II同時銑連桿大小頭孔兩側(cè)端面專用組合銑床專用夾具硬質(zhì)合金端銑刀專用量具鉆連桿小頭孔 高速鋼直柄麻花鉆擴(kuò)連桿小頭孔 高速鋼直柄擴(kuò)孔鉆III鉸連桿小頭孔專用組合鉆床專用夾具硬質(zhì)合金直柄機(jī)用鉸刀 塞規(guī)IV 分離連桿體和連桿蓋專用組合銑床專用夾具高速鋼鋸片銑刀V 銑連桿體結(jié)合面 專用組合銑床專用夾具硬質(zhì)合金端銑刀專用量具VI 銑連桿蓋結(jié)合面專用組合銑床專用夾具硬質(zhì)合金端銑刀專用量具VII 加工連桿體的螺紋專用組合鉆床專用夾具高速鋼直柄階梯麻花鉆高速鋼細(xì)長柄機(jī)用絲錐專用量具VIII 加工連桿蓋的螺栓孔專用組合鉆床專用夾具高速鋼直柄階梯麻花鉆高速鋼帶整體柱直柄平底锪鉆專用量具IX 人工裝配連桿體和連桿粗鏜大頭孔專用量具X半精鏜大頭孔專用組合鏜床專用夾具硬質(zhì)合金鏜刀專用量具XI 精鏜大頭孔 專用組 專用 硬質(zhì)合金鏜刀 專用量具鏜大頭孔內(nèi)鍵槽合鏜床 夾具 專用量具XII 鏜削小頭孔內(nèi)槽專用組合鏜床專用夾具硬質(zhì)合金鏜刀專用量具XIII 銑小頭孔 R67mm 的槽專用組合銑床專用夾具硬質(zhì)合金錯齒三面刃銑刀專用量具XIV 倒角,檢驗(yàn)2.2 連桿合件關(guān)鍵工序工裝設(shè)計(jì)本夾具主要用來鏜 Φ81 的大頭孔,大頭孔軸線相對于小頭孔軸線有一定的尺寸精度要求。由于本工序是粗鏜、辦精鏜,本夾具可用于本工序內(nèi)的所有工步。設(shè)計(jì)夾具主要考慮在滿足合理性的條件下,如何提高勞動生產(chǎn)率降低勞動強(qiáng)度。2.2.1 工藝裝備本工序的工藝裝備含專用夾具、硬質(zhì)合金鏜刀及專用量具。此處主要設(shè)計(jì)專用夾具。2.2.2 夾具設(shè)計(jì)(1)定位基準(zhǔn)的確定加工的大頭孔為通孔,沿 Z 方向的位移自由度可不予限制,但實(shí)際上以工件的端面定位時,必須限制該方向上的自由度,故應(yīng)按完全定位設(shè)計(jì)夾具。為了降低定位誤差,按基準(zhǔn)重合原則選小頭孔軸線、基面(連桿一側(cè)端面)為基準(zhǔn)。連桿以小頭孔表面、基面(連桿一側(cè)端面)及連桿側(cè)面定位,屬完全定位。(2)夾具的設(shè)計(jì)小頭孔、連桿端面加工完畢可以使用,因此選小頭孔軸線、基面(連桿端面)為定位基準(zhǔn),因此連桿可以使用圓柱銷、夾具體表面及一側(cè)面定位塊來定位,同時為了裝卸方便及提高效率,采用液壓夾具帶動推動塊提供夾緊力,夾緊力施加于連桿另一側(cè)面,以定位塊來平衡夾緊力。(a)定位元件小頭孔圓柱銷小頭孔尺寸為 mm(即 mm) ,采用基孔制。由于本工序之前小頭023.??70H孔已經(jīng)加工完畢,達(dá)到了尺寸要求。小頭孔圓柱銷應(yīng)該能和小頭孔相配合,根據(jù)基孔制常用、優(yōu)先配合可得尺寸 mm ( mm)。連桿體大、小孔中心距為620h?013.?mm,以小頭孔的軸線為定位基準(zhǔn),雖屬“基準(zhǔn)重合” ,無基準(zhǔn)不重合誤差,但1.085?由于定位元件與定位面間存在間隙,造成的基準(zhǔn)位置誤差即定位誤差,其值為:(2-min????dD??1)= 0.023+0.013+0= 0.036 mm —— 定位誤差?D?—— 工件孔的直徑公差?—— 定位銷的直徑公差d—— 孔和銷的最小保證間隙min?此項(xiàng)中心距加工允許誤差為 0.1mm,因此工件在加工過程中能夠保證加工精度要求。(b)夾具體夾具體的作用是將定位、夾緊裝置連成一體,為工件提供一個加工平臺,并能正確安裝在機(jī)床上,加工時,能承受部分切削力。夾具體的尺寸依據(jù)工件、定位元件等相關(guān)零件的尺寸來確定。(c)夾緊元件及夾緊裝置通過查手冊及查閱《金屬切削原理》 ,計(jì)算得鏜削加工的切削力為 1260N。夾具夾緊力至少為 1260N。由于連桿零件屬大批量生產(chǎn)類型,為了提高加工效率,縮短輔助時間,采用液壓缸提供夾緊力,通過動 V 型塊施加夾緊力,裝卸工件方便、迅速。綜上,通過查閱相關(guān)資料選擇 YG 系列液壓缸。3 組合機(jī)床設(shè)計(jì)3.1 組合機(jī)床設(shè)計(jì)的要求本組合機(jī)床主要用來鏜 Φ81 的大頭孔,本工序由粗鏜、辦精鏜大頭孔,本組合機(jī)床用于本工序內(nèi)的所有工步。設(shè)計(jì)組合機(jī)床主要考慮如何布局。本設(shè)計(jì)采用具有移動夾具的多工位組合機(jī)床。并繪制組合機(jī)床“三圖一卡” (就是針對具體,在選定的工藝和結(jié)構(gòu)方案的基礎(chǔ)上,進(jìn)行組合機(jī)床總體方案圖樣文件設(shè)計(jì)) 。其內(nèi)容包括:繪制被加工零件工序圖、加工示意圖、機(jī)床聯(lián)系尺寸總圖和編制生產(chǎn)率計(jì)算卡。(1)被加工零件工序圖被加工零件工序圖是根據(jù)制訂的工藝方案,表示所設(shè)計(jì)的組合機(jī)床(或自動線)上完成的工藝內(nèi)容,加工部位的尺寸、精度、表面粗糙度及技術(shù)要求,加工用的定位基準(zhǔn)、夾壓部位以及被加工零件的材料、硬度和在本機(jī)床加工前加工余量、毛坯或半成品情況的圖樣。(2)加工示意圖加工示意圖是在工藝方案和機(jī)床總體方案初步確定的基礎(chǔ)上繪制的,是表達(dá)工藝方案具體內(nèi)容的機(jī)床工藝方案圖;是設(shè)計(jì)刀具,輔具,夾具,多軸箱和液壓、電氣系統(tǒng)以及選擇動力件,繪制機(jī)床總聯(lián)系尺寸圖的主要依據(jù);是對機(jī)床總體布局和性能的原始要求;也是調(diào)整機(jī)床和刀具所必需的重要技術(shù)文件。(a)刀具的選擇選用硬質(zhì)合金鏜刀配合通用鏜刀桿。鏜刀刀桿直徑至少為 65mm,鏜刀刀桿伸出長度至少為 53mm,鏜刀刀桿伸出長度取 163mm。(b)確定切削轉(zhuǎn)矩、軸向力和切削功率確定切削轉(zhuǎn)矩、軸向力和切削功率是為了分別確定主軸及其他傳動件尺寸、選擇滑臺、主電動機(jī)提供依據(jù)。(c)確定相關(guān)部件鏜削頭選用 1TA20 型頂置式齒輪傳動鏜削頭,選用 1HY25MⅠ型液壓滑臺,以及相配套的 1CL25M 型立柱、1CD251M 型立座側(cè)底座 1AYU63 型多工位移動工作臺。(3)機(jī)床聯(lián)系尺寸總圖機(jī)床聯(lián)系尺寸總圖是以被加工零件工序圖和加工示意圖為依據(jù),并按初步選定的主要通用部件以及確定的專用部件的總體結(jié)構(gòu)而繪制的,是用來表示機(jī)床的配置型式、主要構(gòu)成及各部件安裝位置、相互聯(lián)系、運(yùn)動關(guān)系和操作方位的總體布局圖,用以檢驗(yàn)各部件相對位置及尺寸聯(lián)系能否滿足加工要求和通用部件選擇是否合適;它為多軸箱、夾具等專用部件設(shè)計(jì)提供主要依據(jù);它可以看成是機(jī)床總體外觀簡圖,由其輪廓尺寸,占地面積、操作方式等可以檢驗(yàn)是否適應(yīng)用戶現(xiàn)場使用環(huán)境。(4)生產(chǎn)率計(jì)算卡生產(chǎn)率計(jì)算卡是反映所設(shè)計(jì)機(jī)床的工作循環(huán)過程、動作時間、切削用量、生產(chǎn)率、負(fù)荷率的技術(shù)文件。通過其可以分析所擬定的方案是否滿足要求。實(shí)際生產(chǎn)率小于理想生產(chǎn)率,因此本設(shè)計(jì)滿足要求。4 總結(jié)連桿件外形較復(fù)雜,且剛性較差。且其加工技術(shù)要求很高,所以適當(dāng)定位基準(zhǔn),是保證連桿能否正確加工的重要問題。在設(shè)計(jì)的過程中我充分體會到了“先基準(zhǔn)后一般” “先面后孔” “先主要表面后次要表面”的加工原則。專用組合機(jī)床,突出“專用”二字,是針對具體工序而特制的。切削力、切削轉(zhuǎn)矩、切削功率是專用組合鏜床設(shè)計(jì)的基礎(chǔ),求出以上幾個量鏜床最核心部位——鏜削頭就可以確定了,之后的設(shè)計(jì)圍繞鏜削頭和工件的相對位置及其一些關(guān)鍵件尺寸來選擇其它部件并確定它們的相對位置。通過對汽車連桿合件加工工藝及關(guān)鍵工序工裝的設(shè)計(jì),使我擴(kuò)充了知識庫和經(jīng)驗(yàn),同時增加了完成具體工程的信心。南京理工大學(xué)泰州科技學(xué)院畢業(yè)設(shè)計(jì)(論文)前期工作材料學(xué) 生 姓 名 : 趙彧 學(xué) 號: 05010150系 部 : 機(jī)械工程系專 業(yè) : 機(jī)械工程及自動化設(shè) 計(jì) (論 文 )題 目 : 連桿合件加工工藝及關(guān)鍵工序工裝設(shè)計(jì)指 導(dǎo) 教 師 : 王栓虎 副教授材 料 目 錄序號 名 稱 數(shù)量 備 注1 畢業(yè)設(shè)計(jì)(論文)選題、審題表 12 畢業(yè)設(shè)計(jì)(論文)任務(wù)書 13 畢業(yè)設(shè)計(jì)(論文)開題報(bào)告〔含文獻(xiàn)綜述〕 14 畢業(yè)設(shè)計(jì)(論文)外文資料翻譯〔含原文〕 15 畢業(yè)設(shè)計(jì)(論文)中期檢查表 12009 年 5 月 南京理工大學(xué)泰州科技學(xué)院畢業(yè)設(shè)計(jì)(論文)外文資料翻譯系 部: 機(jī)械工程系 專 業(yè): 機(jī)械工程及自動化 姓 名: 趙彧 學(xué) 號: 05010150 外文出處: http://www.wikipedia.org/ 附 件: 1.外文資料翻譯譯文;2.外文原文。 指導(dǎo)教師評語:簽名: 年 月 日附件 1:外文資料翻譯譯文連桿在活塞往復(fù)式發(fā)動機(jī)內(nèi),連桿連接著裝在曲柄或曲軸上的活塞。 《巧妙的機(jī)械裝置知識》一書這樣寫道:“連桿發(fā)明于 1174 年至 1200 年的某個時候,當(dāng)一個名為阿拉-賈扎里的穆斯林發(fā)明家、工程師和工匠,制造了 5 個機(jī)器來為土耳其阿爾圖格王朝的一位國王泵水——這些機(jī)器的其中之一就使用了連桿。將旋轉(zhuǎn)運(yùn)動轉(zhuǎn)變成往復(fù)運(yùn)動可能需要依靠連接到曲柄上的連桿。 ”雙作用往復(fù)活塞泵是第一個提供自動運(yùn)動的機(jī)器,但其機(jī)構(gòu)和其他如凸輪一類的機(jī)構(gòu)也有助于工業(yè)革命的開啟。內(nèi)燃機(jī)在現(xiàn)代汽車內(nèi)燃發(fā)動機(jī)里,用于發(fā)動機(jī)的連桿通常由鋼制造,但也可以用鋁(目的是為了減輕重量和獲得在犧牲耐久度的條件下吸收強(qiáng)沖擊的能力)或鈦(目的是為了在需要支持力時提供一種既輕又有足夠強(qiáng)度的組合)來制造高性能發(fā)動機(jī)的連桿,或使用鑄鐵,如制造摩托車連桿時就使用鑄件。它們不會嚴(yán)格地固定于一端,于是當(dāng)連桿作上下運(yùn)動和繞曲柄旋轉(zhuǎn)時連桿與活塞之間的夾角就發(fā)生改變。連桿較小的一端連接活塞銷,活塞銷(英國用語)或腕銷,這通常會給連桿以經(jīng)常性的壓力,但連桿仍能相對于活塞轉(zhuǎn)動即“浮動腕銷” 。連桿的大端連接于曲柄上的軸頸處,并隨著由連桿螺栓固定的可更換的軸瓦轉(zhuǎn)動,螺栓將軸承“蓋”固定在連桿的大端處;通常要鉆一個通過軸瓦和連桿的大端小孔,以便使增壓潤滑油能噴到筒壁的一側(cè),來使活塞和活塞環(huán)的運(yùn)動得到潤滑。連桿承受著巨大的壓力,這些壓力來自于由活塞產(chǎn)生的循環(huán)載荷,而事實(shí)上這些壓力來自于每次旋轉(zhuǎn)時的拉伸與松弛,以及隨發(fā)動機(jī)轉(zhuǎn)速增大而急劇增大的載荷。一個失效的連桿,通常被稱為“扔棒” ,它是引起汽車引擎災(zāi)難性故障最常見的原因之一,經(jīng)常使失效的連桿穿過曲軸軸箱的一側(cè),發(fā)動機(jī)會遭受無法彌補(bǔ)的損壞;它可能源于連桿的疲勞缺陷、軸瓦失去潤滑而導(dǎo)致的失效,或源于連桿螺栓的缺陷、不適當(dāng)?shù)木o固,或重復(fù)利用已經(jīng)使用過的(已變形的)螺栓(這是不允許的) 。盡管這些經(jīng)常發(fā)生在競爭激烈的汽車運(yùn)動中,但在為日常駕駛生產(chǎn)的汽車中,這種失效是十分罕見。這是因?yàn)槠嚵悴考纳a(chǎn)中要使用一個比較大的安全系數(shù),同時往往還使用更系統(tǒng)的質(zhì)量控制體系。當(dāng)制造一個高性能發(fā)動機(jī)時,連桿應(yīng)給予極大的關(guān)注,應(yīng)采取一些技術(shù)來消除應(yīng)力,例如磨削連桿的邊緣以達(dá)到表面粗糙度的要求,噴丸以使表面產(chǎn)生壓應(yīng)力(防止裂紋萌生) ,裝配時平衡所有連桿、活塞組合件的重量使每對的重量相同以及采用磁力探傷法來探測材料內(nèi)部的微小裂紋,這些看不見的微小裂縫將會產(chǎn)生破壞應(yīng)力造成連桿失效。此外,扭緊連桿螺栓時,應(yīng)非常注意扭矩的大小;通常這些螺栓必須更換,而不是重復(fù)使用。連桿的大端被制造成一個整體,并使其在機(jī)械加工之后能與大端軸瓦準(zhǔn)確裝配。因此,大端的“帽子”在連桿與連桿之間不具有互換性,而且當(dāng)重新制造一個引擎時,必須小心,以確保不同連桿的軸瓦不被亂用。無論是連桿還是與其相配合的軸瓦,通常都會在發(fā)動機(jī)缸體上刻上相應(yīng)的型號。目前有一些發(fā)動機(jī)(如福特的 4.6 升引擎,還比如克萊斯勒的 2.0 升引擎)其連桿采用粉末冶金技術(shù)制造,粉末冶金技術(shù)不僅能精確控制尺寸和重量以減少機(jī)械加工工作量而且還能減少額外的機(jī)械配平。軸瓦因擠壓而與連桿分離,結(jié)果導(dǎo)致了不平滑的斷裂面,這是由于粉末金屬的顆粒造成的。這確保了重新裝配后,軸瓦能與連桿精確地配合,而傳統(tǒng)加工方法制造的連桿與軸瓦,只有當(dāng)兩者的接觸面表面的表面粗糙度都很小時才能達(dá)到較小的誤差。發(fā)動機(jī)磨損的一個主要原因是由于曲軸通過連桿施加于活塞的側(cè)向力,通常將汽缸磨成橢圓形截面,而不是圓形截面,因此不可能使活塞環(huán)與氣缸側(cè)壁緊密接觸。從力學(xué)角度來說延長連桿的長度可相應(yīng)地減少上述側(cè)向力,這樣一來會使引擎壽命延長。然而,對一已知的發(fā)動機(jī)缸體來說,連桿的長度加上活塞行程,其和是一個固定的值,這個固定值由曲軸和氣缸座(氣缸座用來固定活塞蓋)頂部之間的固定距離來決定。因此,對一個已知的氣缸而言能得到更長的行程,可提供更大的排量和功率。相反,較短的連桿(或較小壓縮行程的活塞) ,會導(dǎo)致氣缸加速地磨損。復(fù)合連桿眾多多缸布局的發(fā)動機(jī)——如 V – 12 型發(fā)動機(jī)——幾乎沒有可用于在有限長度的曲軸上安裝連桿軸頸的空間。這是一個難以調(diào)和的矛盾,而且若按普通的方式安裝,其往往會導(dǎo)致發(fā)動機(jī)的失敗。 最簡單的解決辦法是使用簡單的連桿,這種最簡單的方法通常用于汽車引擎。這就要求連桿軸瓦要更窄,但對于一個高性能的引擎來說其會增加軸瓦的負(fù)荷及失效的風(fēng)險(xiǎn)。這也意味著對置的氣缸不完全位于一條直線上。在某些類型的引擎內(nèi),主動連桿帶有一個或多個環(huán)形銷,環(huán)形銷用來連接其他氣缸上的從動連桿相對小一些的大端。徑向引擎的每一邊通常是一個氣缸有一個主動連桿,余下的其它氣缸則配有從動連桿。對于確定設(shè)計(jì)的 V 形引擎,一對對置的氣缸使用一對主/從動連桿。這樣的一個缺點(diǎn)是,輔助連桿的行程稍微短于主動連桿,從而使 V 形發(fā)動機(jī)產(chǎn)生更大的振動。高性能航空發(fā)動機(jī)的通常解決方案是使用一個“叉狀”連桿。一個連桿在大端處一分為二,另一個變薄以與這個叉狀連桿相配。軸頸仍然由多個氣缸共用。勞斯萊斯默林發(fā)動機(jī)就使用這種形式。曲柄連桿機(jī)構(gòu)的類型及特點(diǎn)內(nèi)燃機(jī)中采用曲柄連桿機(jī)構(gòu)的型式很多,按運(yùn)動學(xué)觀點(diǎn)可分為三類,即:中心曲柄連桿機(jī)構(gòu)、偏心曲柄連桿機(jī)構(gòu)和主副連桿式曲柄連桿機(jī)構(gòu)。中心曲柄連桿機(jī)構(gòu)的特點(diǎn)是氣缸中心線通過曲軸的旋轉(zhuǎn)中心,并垂直于曲柄的回轉(zhuǎn)軸線。這種型式的曲柄連桿機(jī)構(gòu)在內(nèi)燃機(jī)中應(yīng)用最為廣泛。一般的單列式內(nèi)燃機(jī),采用并列連桿與叉形連桿的 V 形內(nèi)燃機(jī),以及對置式活塞內(nèi)燃機(jī)的曲柄連桿機(jī)構(gòu)都屬于這一類。偏心曲柄連桿機(jī)構(gòu)的特點(diǎn)是氣缸中心線垂直于曲軸的回轉(zhuǎn)中心線,但不通過曲軸的回轉(zhuǎn)中心,氣缸中心線距離曲軸的回轉(zhuǎn)軸線具有一偏移量 e。這種曲柄連桿機(jī)構(gòu)可以減小膨脹行程中活塞與氣缸壁間的最大側(cè)壓力,使活塞在膨脹行程與壓縮行程時作用在氣缸壁兩側(cè)的側(cè)壓力大小比較均勻。主從連桿式曲柄連桿機(jī)構(gòu)的特點(diǎn)是:內(nèi)燃機(jī)的一列氣缸用主動連桿,其它各列氣缸則用從動連桿,這些連桿的下端不是直接接在曲柄銷上,而是通過從動連桿銷裝在主連桿的大端上,形成了“關(guān)節(jié)式”運(yùn)動,所以這種機(jī)構(gòu)有時也稱為“關(guān)節(jié)曲柄連桿機(jī)構(gòu)” 。在關(guān)節(jié)曲柄連桿機(jī)構(gòu)中,一個曲柄可以同時套上幾副連桿和活塞,這種結(jié)構(gòu)可使內(nèi)燃機(jī)長度縮短,結(jié)構(gòu)緊湊,廣泛地應(yīng)用于大功率的坦克和機(jī)車用 V 形內(nèi)燃機(jī)。鏜在機(jī)械加工,鏜削加工的過程是一個擴(kuò)孔的過程,這個孔可以是鉆出來的(或鑄造得到的) ,鏜孔通過單點(diǎn)切削刀具(或一個鏜頭含有若干個這樣的刀具)來加工,例如用鏜削方法加工炮桶。鏜削加工能使孔達(dá)到更精確的尺寸,而且還可以用于錐形孔的加工。 鏜削有時也用于孔的加工。鏜孔機(jī)對較小的鏜削加工過程可以在車床上進(jìn)行,但對于較大工件的加工則需要使用特殊的鏜床(工件圍繞一個垂直軸旋轉(zhuǎn))或臥式鏜床(圍繞水平軸旋轉(zhuǎn)) 。通過轉(zhuǎn)動變換刀具的安裝角度也可以加工錐形孔。鏜床(類似于銑床,如經(jīng)典的范諾曼型)擁有多種尺寸和類型。工件直徑通常是 1 – 4 米( 3-12 英尺) ,但也可達(dá) 20 米(六十英尺) 。對電力的需求可高達(dá) 200 匹馬力。其控制系統(tǒng)可以以計(jì)算機(jī)為基礎(chǔ),允許自動控制和提高一體性。由于鏜削加工可以降低產(chǎn)品上已有孔的公差,因此一些設(shè)計(jì)的注意事項(xiàng)必須得注意。首先,大的長徑比是不希望的,因?yàn)檫@樣會使刀具變形。其次,不能加工盲孔(孔的深度不超過工件的厚度) 。中斷的內(nèi)部工作表面(即在刀具與加工表面間有不連續(xù)的接觸)應(yīng)該避免。裝有刀頭的鏜桿是一個懸臂梁,必須有非常高的剛度。鍛造鍛造是一種利用局部壓力使金屬成型的方法。冷鍛是在室溫下或接近室溫下進(jìn)行的鍛造。熱鍛是在高溫下進(jìn)行,高溫使金屬更容易成形和降低斷裂的可能性。溫鍛是在室溫和熱鍛溫度之間的溫度下進(jìn)行。鍛造可對從不足 1 千克到 170 噸的工件進(jìn)行加工。經(jīng)鍛造加工的零部件通常還需作進(jìn)一步處理,以便得到最終的產(chǎn)品。附件 2:外文原文Connecting rodIn a reciprocating piston engine, the connecting rod or conrod connects the piston to the crank or crankshaft. The connecting rod was invented sometime between 1174 and 1200 when a Muslim inventor, engineer and craftsman named al-Jazari built five machines to pump water for the kings of the Turkish Artuqid dynasty — one of which incorporated the connecting rod. Transferring rotary motion to reciprocating motion was made possible by connecting the crankshaft to the connecting rod, which was described in the "Book of Knowledge of Ingenious Mechanical Devices". The double-acting reciprocating piston pump was the first machine to offer automatic motion, but its mechanisms and others such as the cam, would also help initiate the Industrial Revolution.Internal combustion engines In modern automotive internal combustion engines, the connecting rods are most usually made of steel for production engines, but can be made of aluminium (for lightness and the ability to absorb high impact at the expense of durability) or titanium (for a combination of strength and lightness at the expense of affordability) for high performance engines, or of cast iron for applications such as motor scooters. They are not rigidly fixed at either end, so that the angle between the connecting rod and the piston can change as the rod moves up and down and rotates around the crankshaft.The small end attaches to the piston pin, gudgeon pin (the usual British term) or wrist pin, which is currently most often press fit into the conrod but can swivel in the piston, a "floating wrist pin" design.The big end connects to the bearing journal on the crank throw, running on replaceable bearing shells accessible via the con rod bolts which hold the bearing "cap" onto the big end; typically there is a pinhole bored through the bearing and the big end of the con rod so that pressurized lubricating motor oil squirts out onto the thrust side of the cylinder wall to lubricate the travel of the pistons and piston rings.The con rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and relaxing with every rotation, and the load increases rapidly with increasing engine speed. Failure of a connecting rod, usually called "throwing a rod" is one of the most common causes of catastrophic engine failure in cars, frequently putting the broken rod through the side of the crankcase and thereby rendering the engine irreparable; it can result from fatigue near a physical defect in the rod, lubrication failure in a bearing due to faulty maintenance, or from failure of the rod bolts from a defect, improper tightening, or re-use of already used (stressed) bolts where not recommended. Despite their frequent occurrence on televised competitive automobile events, such failures are quite rare on production cars during normal daily driving. This is because production auto parts have a much larger factor of safety, and often more systematic quality control.When building a high performance engine, great attention is paid to the con rods, eliminating stress risers by such techniques as grinding the edges of the rod to a smooth radius, shot peening to induce compressive surface stresses (to prevent crack initiation), balancing all con rod/piston assemblies to the same weight and Magnafluxing to reveal otherwise invisible small cracks which would cause the rod to fail under stress. In addition, great care is taken to torque the con rod bolts to the exact value specified; often these bolts must be replaced rather than reused. The big end of the rod is fabricated as a unit and cut or cracked in two to establish precision fit around the big end bearing shell. Therefore, the big end "caps" are not interchangeable between con rods, and when rebuilding an engine, care must be taken to ensure that the caps of the different con rods are not mixed up. Both the con rod and its bearing cap are usually embossed with the corresponding position number in the engine block.Recent engines such as the Ford 4.6 liter engine and the Chrysler 2.0 liter engine, have connecting rods made using powder metallurgy, which allows more precise control of size and weight with less machining and less excess mass to be machined off for balancing. The cap is then separated from the rod by a fracturing process, which results in an uneven mating surface due to the grain of the powdered metal. This ensures that upon reassembly, the cap will be perfectly positioned with respect to the rod, compared to the minor misalignments which can occur if the mating surfaces are both flat.A major source of engine wear is the sideways force exerted on the piston through the con rod by the crankshaft, which typically wears the cylinder into an oval cross-section rather than circular, making it impossible for piston rings to correctly seal against the cylinder walls. Geometrically, it can be seen that longer con rods will reduce the amount of this sideways force, and therefore lead to longer engine life. However, for a given engine block, the sum of the length of the con rod plus the piston stroke is a fixed number, determined by the fixed distance between the crankshaft axis and the top of the cylinder block where the cylinder head fastens; thus, for a given cylinder block longer stroke, giving greater engine displacement and power, requires a shorter connecting rod (or a piston with smaller compression height), resulting in accelerated cylinder wear.Compound rodsMany-cylinder multi-bank engines such as a V-12 layout have little space available for that many connecting rod journals on a limited length of crankshaft. This is a difficult compromise to solve and its consequence has often led to engines being regarded as failures.The simplest solution, almost universal in road car engines, is to use simple rods. This requires the rod bearings to be narrower, increasing bearing load and the risk of failure in a high-performance engine. This also means the opposing cylinders are not exactly in line with each other.In certain types of engine, the master rod carries one or more ring pins to which are bolted the much smaller big ends of slave rods on other cylinders. Radial engines typically have a master rod for one cylinder and slave rods for all the other cylinders in the same bank. Certain designs of V engines use a master/slave rod for each pair of opposite cylinders. A drawback of this is that the stroke of the subsidiary rod is slightly shorter than the master, which increases vibration in a vee engine.The usual solution for high-performance aero-engines is a "forked" connecting rod. One rod is split in two at the big end and the other is thinned to fit into this fork. The journal is still shared between cylinders. The Rolls-Royce Merlin used this style.Crank linkage of the type and characteristicsThe use of the internal combustion engine crank linkage of many types, according to kinematics perspective can be divided into three categories, namely: Heart crank linkage, the eccentric crank linkage and the main vice-link crank linkage. Centre crank linkage is characterized by the cylinder through the centerline of the crankshaft rotation centre and perpendicular to the axis of rotation of the crank. This type of linkage in the internal combustion engine crank in the most widely used. The single-engine general, tied for linkage with the use of the V-shaped chaxing link the internal combustion engine, and the home of the piston internal combustion engine crank linkage fall into this category. Eccentric crank linkage is characterized by vertical cylinder centerline of the crankshaft rotating in the center, but not by crankshaft rotary centre, the cylinder centerline distance between the crankshaft with a rotary axis offset e. This crank linkage institutions can reduce the swelling in the itinerary of the piston and cylinder intramural largest lateral pressure so that the pistons in the expansion programme and pressure reduction programme in the cylinder wall at the role of lateral pressure on both sides of the relatively uniform size. Vice-link the main crank linkage is characterized by: the internal combustion engine cylinder with a main link, the other out vice-link cylinder used, these are not direct link to the bottom of the crank pins, but on sale through the deputy link with in the main link of the big heads, formed a "joint" movement, such institutions also sometimes referred to as "joint song stalk linkage ".Crank linkage in the joint, a crank can put a few of connecting rod and piston, This structure will shorten the length of the internal combustion engine, compact and widely used in high-power locomotives used tanks and V-shaped internal combustion engine.Boring In machining, boring is the process of enlarging a hole that has already been drilled (or cast), by means of a single-point cutting tool (or of a boring head containing several such tools), for example as in boring a cannon barrel. Boring is used to achieve greater accuracy of the diameter of a hole, and can be used to cut a tapered hole.The term boring is also sometimes used for drilling a hole.Machine BoringThe boring process can be carried out on a lathe for smaller operations, but for larger production pieces a special boring mill (work piece rotation around a vertical axis) or a horizontal boring machine (rotation around horizontal axis) are used. A tapered hole can also be made by swiveling the head.The boring machines (similar to the milling machines such as the classic Van Norman) come in a large variety of sizes and styles. Work piece diameters are commonly 1-4m (3-12 ft) but can be as large as 20m (60ft). Power requirements can be as much as 200 hp. The control systems can be computer-based, allowing for automation and increased consistency.Because boring is meant to decrease the product tolerances on pre-existing holes, several design considerations must be made. First, large length-to-bore-diameters are not preferred due to cutting tool deflection. Next, through holes are preferred over blind holes (holes that do not traverse the thickness of the work piece). Interrupted internal working surfaces—where the cutting tool and surface have discontinuous contact—should be avoided. The boring bar is the protruding arm of the machine that holds cutting tool(s), and must be very rigid.ForgingForging is the term for shaping metal by using localized compressive forces. Cold forging is done at room temperature or near room temperature. Hot forging is done at a high temperature, which makes metal easier to shape and less likely to fracture. Warm forging is done at intermediate temperature between room temperature and hot forging temperatures. Forged parts can range in weight from less than a kilogram to 170 metric tons.Forged parts usually require further processing to achieve a finished part.
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