基本的加工工序切削 鏜削和銑削

1、溝婁減慨黨持癭摭付鬈釉隸本科生畢業(yè)設(shè)計(jì) (論文)冂芽該袼賤媾澌苣疇杉脫蓍男胱貼蠔厚鬻喀郴汜葳抵臘外 文 翻 譯蕨鸞蜓颮愆次爺胬碌撟閿宋鰓幀蓰脈勖稗褸阻笨綈育典瘺挹蠓惰莨烽睿蛔葚錘袁針啉宀笳舵叮亓遲筑湓鰳摑愾原 文 標(biāo) 題靛釁冬亟蝸賢諷悝孝鸝然臘Basic Machining OperationsTurning ,Boring and Milling蒹碉如琛辛偶鐫幃幕膿應(yīng)輛譯 文 標(biāo) 題洫糅中螞鋌逅慝兵畏銥敉煊基本的加工工序切削 鏜削和銑削窆賅拇狄氆楔催道眉羞釹醺作者所在系別記睫绱宦綁諏賺訾恒盾梃孱機(jī)械工程系四匾侖腆輇戾炕紉素現(xiàn)謁蝽作者所在專業(yè)護(hù)相苫橛魑瞧緱閽字蝻麋麾機(jī)械設(shè)計(jì)制造及其自動(dòng)化靜敫虬

2、痄閘溉牟稟戤汔繽然作者所在班級(jí)瘼傭靛照壞春高獸會(huì)戚寡璽 漁徠假澆鑷怪爽胛俾鳊榪掏作 者 姓 名巢菥嶸易豬蚓氯歙澧隙體耩 可套獼曦踉厄涓夾翳溻綁舉作 者 學(xué) 號(hào)紀(jì)刻噍萬蠻癯尢渦既駟晟鶴 址瀾旅檐具晾畎徐璋蹭閂婊指導(dǎo)教師姓名浩垅事婿爬源鍪累疑翅臃庹 蔡佬危強(qiáng)隋鐐幔狄蛙魃緹蚴指導(dǎo)教師職稱彘釋垮碲懣齲育旱漸庠髂豪 教授凡稍想甚漱嶸髻銳纛袞裼弛完 成 時(shí) 間浞窠槌酯鮑重儀螺艇避氮氽 日唪井賃砍瘍螨燁屋鋌頁諦荮大琺蹩?jī)?cè)締艘虧惝哂州抵鉅 鱘罾然嘁鉤馓淑私僮塵跏靶譯文標(biāo)題秸砦鎬類頓獨(dú)咆陴瓊否磲囂基本的加工工序切削 鏜削和銑削樁鄞姜唄閔孀惦圖鼗叼括劃原文標(biāo)題硯蕹鉉莞搟褂踮鰲嘁峁咫和Basic Machining

3、 OperationsTurning ,Boring and Milling 晦馭珩劣硤寰鬼夂磯酵奕屁作 者廨笮壤孫鎊愷腮勺歙跺埡跌B.W.Nile趟禺稻湓蝦先刮猩攘敦酹舶譯 名雋暮獻(xiàn)貉族暴弛紳諏腥垤彩本.沃.聶邇胚葚岳崳疋闥腓漤地氘僂魄國(guó) 籍言照嬉淅既癱綠永凈詢肚械加拿大鯖覘等辟劓街本詈靡署弋風(fēng)原文出處攢攻龜腿強(qiáng)褐骶犟骯繡嚯硝Modern Manufacturing Process Engineering 介閹家塊貢虹話鬟淮裔蜈馀譯文：氤淋骶裙丁噩塢劍歿新癰癆基本的加工工序切削 鏜削和銑削析薨紉孩敏棄篇丿趁究旅已基本的加工工序謦碳杭詈摶鯖糗妲煥汛殮別機(jī)床是從早期的埃及人的腳踏動(dòng)力車床和約翰威

4、爾金森的鏜床發(fā)展而來。它們用于為工件和刀具兩者提供剛性支撐并且可以精確控制它們的相對(duì)位置和相對(duì)速度?；旧现v，在金屬切削中一個(gè)磨尖的楔形工具以緊湊螺紋形的切屑形式從有韌性工件表面上去除一條很窄的金屬。切屑是廢棄的產(chǎn)品，與其工件相比，它相當(dāng)短但是比未切屑的部分厚度有相對(duì)的增加。機(jī)器表面的幾何形狀取決于刀具的形狀以及加工過程中刀具的路徑。杉渾燈快駭淆锎櫞靴揖庹燉 大多數(shù)加工工序生產(chǎn)出不同幾何形狀的部件。如果一個(gè)粗糙的柱形工件繞中心軸旋轉(zhuǎn)而且刀具穿透工件表面并沿與旋轉(zhuǎn)中心平行的方向前進(jìn)，就會(huì)產(chǎn)生一個(gè)旋轉(zhuǎn)面，這道工序叫車削。如果以類似的方式加工一根空心管的內(nèi)部，則這道工序就叫鏜削。制造一個(gè)直徑均勻變化

5、的錐形外表面叫做錐體車削。如果刀具尖端以一條半徑可變的路徑前進(jìn)，就可以制造出象保齡球桿那種仿形表面；如果工件足夠短而且支撐具有足夠的剛性，仿形表面可以通過進(jìn)給一個(gè)垂直于旋轉(zhuǎn)軸的仿形刀具來制造。短的錐面或柱面也可以仿形切削。乜洫咖渲嶠頂諍櫸彝粼要優(yōu)常常需要的是平坦的或平的表面。它們可以通過徑向車削或端面端面車削來完成，其中刀具尖端沿垂直與旋轉(zhuǎn)軸的方向運(yùn)動(dòng)。在其他情況下，更方便的是固定工件不動(dòng)，以一系列直線方式往復(fù)運(yùn)動(dòng)刀具橫過工件，在每次切削行程前具有一定橫向進(jìn)給量。這種龍門刨削，和牛頭刨削是在刨窗上進(jìn)行的。大一些的工件很容易保持刀具固定不動(dòng)，而像龍門刨削那樣在其下面拉動(dòng)工件，再每次往復(fù)進(jìn)給刀具。

6、仿形面可以通過使用仿形刀具來制造。睥又蕙篡率娶獫瞧悚瘛髏辟也可以使用多刃刀具。鉆削使用兩刃刀具，空深可達(dá)鉆頭直徑的5-10倍。不管是鉆頭轉(zhuǎn)動(dòng)還是工件轉(zhuǎn)動(dòng)，切削刃與工件之間的相對(duì)運(yùn)動(dòng)是一個(gè)重要因素。在銑削作業(yè)中，有許多切削刃的旋轉(zhuǎn)銑刀與工件相接合，這種工件相對(duì)銑刀運(yùn)動(dòng)緩慢。根據(jù)銑刀的幾何形狀和進(jìn)給的方式，可以加工出平面和仿形面?？梢允褂盟交虼怪毙D(zhuǎn)軸，工件可以沿三個(gè)坐標(biāo)方向中的任意一個(gè)進(jìn)給。撞聳衛(wèi)截搿庫望曼匾窮辛塵基本的機(jī)床幺馴柃真炊崮跪猾殲蜂坫緇機(jī)床用于以切屑的形式從韌性材料上去除金屬來加工特殊幾何形狀和精密尺寸的部件。切屑是廢品，其變化形狀從像鋼這樣的韌性材料的長(zhǎng)的連續(xù)帶狀屑到鑄鐵形成的易

7、于處理、徹底斷掉的切屑，從處理的觀點(diǎn)來講，不想要長(zhǎng)的連續(xù)帶狀屑。機(jī)床完成5種基本的金屬切削工藝：車削、刨削、鉆削、銑削和磨削。其他所有金屬切削工藝都是這5種基本工藝的變形。例如：鏜削是內(nèi)部車削；鉸削、錐體車削和平底锪孔則修改鉆孔，與鉆削有關(guān)；滾齒與切齒是基本銑削作業(yè)；弓鋸削和拉削是銑削和磨削的一種形式；而研磨、超精加工、拋光和磨光是磨削和研磨切削作業(yè)的各種變化形式。因此，僅有4種使用專用可控幾何形狀的刀具基本機(jī)床：1. 車床，2. 刨床，3. 鉆床，4. 銑床。磨削工藝形成碎屑，但是磨粒的幾何形狀不可控制。剎鳩鄖科掠麗聒匝鈰脅夥囤不同加工工藝切削的材料的兩和速度卻不相同。可能極大，如大型車削作

8、業(yè)；或者極小，如磨削和超精加工作業(yè)，只有表面高出的點(diǎn)被去除。墚蛹娃起汛章鈣肩猿縛赧幢機(jī)床完成3種主要功能：1. 剛性支撐工件或工件夾具以及切削刀具；2. 提供工件與切削刀具之間的相對(duì)運(yùn)動(dòng)；3. 提供了一定范圍的速度進(jìn)給，通常每種4-32種選擇。廈焙諞林嶺愛夷劾辜鴝謖插加工中的速度和進(jìn)給倒隊(duì)南淦得鄰髹票救沐霍技切削速度、進(jìn)給和切深是經(jīng)濟(jì)加工的3個(gè)主要變量，其他變量還有工件和工具材料、冷卻劑以及切削刀具的幾何形狀。金屬切削的速率和加工所需的功率就決定于這些變量。夔朝昕朊拒企錘律謬煳蠹符切割深度、進(jìn)給和切削速率是任何金屬切削作業(yè)中必須都建立的設(shè)置。它們都影響切削力、功率和對(duì)金屬切削的速率。可以通過把

9、它們與留聲機(jī)的唱針和唱片相比較給出定義。切削速度（V）由任意時(shí)刻唱片表面相對(duì)于拾音器支臂內(nèi)部的唱針的速度來表示；進(jìn)給由唱針每圈徑向向內(nèi)的前進(jìn)量或者由兩個(gè)相鄰槽的位置差來表示。切削的深度是唱針進(jìn)入的量或者是槽的深度?？P束奄已褳息喧呋鴕偵頰篪切削廠杯槌眚順徹榍苔鞋曹捺昧 那些在外表面上用單刃刀具完成的工序叫車削。除鉆削、鉸削和錐體車削外，在內(nèi)表面的作業(yè)也由單刃刀具完成。峰贓耄兇找鮒垤揪全踹荇箏包括車削和鏜削在內(nèi)的所有加工工序都可以分為粗加工、精加工、和半精加工。粗加工工序的目的是盡可能迅速且高效地去除大量的材料，在工件上只留下少量的材料給精加工工序。精加工工序用以獲得工件最終的大小、形狀和表面光潔

10、度。有時(shí)，在精加工工序前進(jìn)行半精加工作業(yè)以便在工件上留下少的、預(yù)定的和均勻量的原材料供精加工去除。仝訐付誑奎鱔絆甏堿鍵疊篙通常，較長(zhǎng)的工件是在一個(gè)或兩個(gè)車床頂尖的支撐下進(jìn)行的。用于安裝車床頂尖的錐形孔叫做頂尖孔，它是在工件的端部鉆出的通常沿著柱形部件的軸心。與尾架鄰近的工件端部總是由尾架頂尖支撐，而挨著主軸箱的一端則由主軸箱頂尖支撐或裝在卡盤內(nèi)。工件的主軸箱一端可以裝在一個(gè)四爪卡盤或套爪卡盤內(nèi)。這種方法牢固地夾持工件并且把功率平穩(wěn)地傳送到工件；由卡盤提供的額外支撐減少了車削作業(yè)時(shí)發(fā)生震動(dòng)的傾向。如果仔細(xì)地將工件精確的固定在卡盤上，用這種方法將獲得精密的結(jié)果。舡福鼗矸淼航吸依兆屐榻嗯通過將工件支

11、撐在兩個(gè)頂尖之間可以獲得非常精確的結(jié)果。一個(gè)車床夾頭夾在工件上；然后由安裝在主軸前端的撥盤一起帶動(dòng)。先加工工件的一端，然后可以在車床上將工件掉頭加工另一端。工件上的頂尖孔是用作精確定位面以及承受工件重量和抵抗車削力的支撐面。在工件被拆下后，頂尖孔可以精確地將其裝回機(jī)床。工件千萬不要同時(shí)通過卡盤和頂尖安裝在主軸箱一端。雖然這樣似乎是一種快捷方法，但是這樣做使得工件受力不均勻，頂尖的對(duì)正作用不能維持，而且爪的壓力可能損壞頂尖孔、車床頂尖甚至車床主軸。幾乎被獨(dú)自用在大量生產(chǎn)工件上的補(bǔ)償或浮動(dòng)爪式卡盤是上述的一個(gè)例外。這些卡盤是自動(dòng)偏心夾緊卡盤不能起到普通三爪或四爪卡盤同樣的作用。鰲抬榀梨彘摶讀舞桊畜

12、厄邂直徑非常大的工件雖然有時(shí)安裝在兩個(gè)頂尖上，但是最好用花盤爪把它們固定在主軸箱端以獲得流暢的動(dòng)力傳輸；此外，可以把它們制造成專用部件，但是一般沒有提供足夠大的車床夾頭來傳輸動(dòng)力。除非是安裝在花盤上，花盤爪像卡盤爪，其主軸軸承上的外伸要比大卡盤上的也要少一些。舍述辜酪栝躬訌糙跪澶嫣佑鏜削羌扔笤貉惶鮞聃眺謖唁徵馗在車床上鏜孔的目的是：韜挽旭躇薊嶇鸕繰嬴皇崛螬1. 擴(kuò)孔；捕叱人療搔苫運(yùn)釕灌蓰痘胙2. 把孔加工到所需直徑；槿更餞詠胯夤锨垮咼磧逭啜3. 精確的為孔定位；詆吹汾嬪澄醋剔掀燦節(jié)據(jù)弘4. 在孔內(nèi)獲得好的表面光潔度。幛盾鮮串棟射嫗乞鰒韃石領(lǐng)當(dāng)拖板縱向移動(dòng)而工件繞車床的軸線旋轉(zhuǎn)時(shí)，鏜孔工具的運(yùn)動(dòng)

13、平行于車床上的軸線。當(dāng)菥挹砦委罾楓跟讒鈑鍰鯤弗兩種運(yùn)動(dòng)結(jié)合起來鏜孔時(shí)，就會(huì)與車床的旋轉(zhuǎn)軸同心。通過把工件固定在車床上可以精確定位孔的位置以使待加工孔所環(huán)繞的軸與車床的旋轉(zhuǎn)軸一致。當(dāng)鏜削工序與用于車削和刮削工序的供桌設(shè)置相同時(shí)，實(shí)際上可以達(dá)到理想的同心與垂直。瑋左淘鱉瞑魄姜闖帆髭匹桑鏜孔工具固定在一根由拖板通過進(jìn)給的鏜桿上。根據(jù)待做的工作來使用這一設(shè)計(jì)的變化形式。如果有的話，所用的倒角總是應(yīng)該小些。而且，鏜孔工具前端的半徑一定不能太大。用于鏜孔的切削速度可以等于車削速度。但是，在計(jì)算車床主軸速度時(shí)，應(yīng)當(dāng)使用完成后的或最大的孔徑。鏜削的進(jìn)刀速度通常比車削的小一點(diǎn)以補(bǔ)償鏜桿剛性的不足。相忮璞履嫁琛文

14、慚菟蘺狺姑鏜削工序一般分兩步完成，即粗鏜和精鏜。粗鏜工序的目的是快速，高效地去除多余的金屬；而精鏜工序的目的是獲得所需的尺寸、表面光潔度、和孔的位置?？椎某叽缤ㄟ^使用試切來獲得。孔的直徑可以用內(nèi)卡尺和為千分尺測(cè)量。測(cè)量?jī)x表或內(nèi)千分卡尺直接測(cè)量直徑。藪汾侯郄高倀糯簾萌諉挎踺型心孔和要鉆的孔有時(shí)相對(duì)與車床的旋轉(zhuǎn)是偏心的。當(dāng)鏜孔工具進(jìn)入工件時(shí)，鏜桿在孔的一邊切口比一邊深，當(dāng)才用這深切口時(shí)就會(huì)更偏斜，結(jié)果鏜的孔不與工件旋轉(zhuǎn)同心。這一影響通過利用淺切口在整個(gè)孔加工中進(jìn)行幾次加工來糾正。因?yàn)槊總€(gè)淺切口使形成的孔比使用先切口形成的孔更加同心。在完工前，進(jìn)行精加工，孔應(yīng)該與工件的旋轉(zhuǎn)同心以確保完工時(shí)孔會(huì)精確定

15、位。亠顙釷夕卜蚪銃佾揭擢潼謠肩，溝槽，輪廓， 錐度和螺紋也應(yīng)該在孔內(nèi)鏜出。內(nèi)槽是用與外部開槽工具相似的工具切削。鏜削內(nèi)槽的步驟非常類似于車削肩部的步驟。大的肩部使用前導(dǎo)裝置定位的鏜孔工具進(jìn)行刮削，使用橫向滑板進(jìn)給工具。內(nèi)部輪廓使用車床上的描摹附件加工。仿行板附件安裝在橫向滑板上，靠模指跟隨標(biāo)準(zhǔn)剖面板的輪廓線運(yùn)動(dòng)。這使刀具對(duì)應(yīng)于標(biāo)準(zhǔn)剖面樣板的輪廓線的路徑進(jìn)行移動(dòng)。這樣標(biāo)準(zhǔn)剖面樣板的輪廓就在孔內(nèi)的得到復(fù)制。標(biāo)準(zhǔn)剖面樣板精確安裝在一個(gè)專用的滑板上，滑板可以在兩個(gè)方向上進(jìn)行精確調(diào)整以使刀具與工件以正確的關(guān)系對(duì)正。這臺(tái)車床有一個(gè)偏心夾型的主軸前端，允許在任意一方向旋轉(zhuǎn)時(shí)進(jìn)行切削。正常的車削是在主軸逆時(shí)針

16、轉(zhuǎn)動(dòng)時(shí)進(jìn)行的；鏜削切削是在主軸順時(shí)針方向或“向后”轉(zhuǎn)動(dòng)時(shí)進(jìn)行的。這允許在孔的“后側(cè)”進(jìn)行鏜削切削，在車床前面，從操作者的位置易于看到后孔。在具有螺紋主軸前端的車床上不應(yīng)這么做，因?yàn)榍邢髁?huì)旋松卡盤。斑鶘懊架瘊顢槭裥胙沼靦殯銑削羈锿寬抿鍥玎樨稈螂締經(jīng)斂銑削是一種通過工件與多刃旋轉(zhuǎn)銑刀間的相對(duì)運(yùn)動(dòng)去除材料的加工工藝。在一些應(yīng)用中，工件固定而旋轉(zhuǎn)的銑刀以一定進(jìn)給速度移過工件（橫過）；在其他應(yīng)用中，工件與銑刀既彼此相對(duì)運(yùn)動(dòng)，又相對(duì)銑床運(yùn)動(dòng)。但是，更常見的是工件以一個(gè)相對(duì)較低的運(yùn)動(dòng)速度或進(jìn)給速度朝正在高速旋轉(zhuǎn)的銑刀前進(jìn)，而銑刀軸保持在一個(gè)固定位置。銑削工藝特有的性能是每個(gè)銑刀齒都以小的單個(gè)切屑的形式切去

17、一部分原料?？梢栽谠S多不同的機(jī)器上進(jìn)行銑削作業(yè)。揲賑雇鵓釜汾含遨描孺匐撿由于工件和銑刀都可以彼此相對(duì)運(yùn)動(dòng)，銑削可以獨(dú)立的或以組合方式完成各式各樣的作業(yè)。各種應(yīng)用包括平面或仿行面，縫，槽，退刀槽，螺紋和其他外形的加工。匙攫亡挨疸翕止憧羹爪異敖銑削是一種最為通用而又復(fù)雜的加工方法。該工藝比任何其他基本加工方法在所用機(jī)器的種類，工件運(yùn)動(dòng)以及加工工具種類方面都具有更多的變化。利用銑削去除材料的重要優(yōu)點(diǎn)包括原料切削速度高，能形成相對(duì)光滑的表面光潔度以及可應(yīng)用的刀具更為多樣。道具的切削刀刃可以仿行以形成任何復(fù)雜的表面。數(shù)黜北俊蹺變級(jí)影收莒拳俗主要的銑削方法有周銑和端銑，此外，還有許多相關(guān)方法，他們屬于這2

18、種方法的變化形式，這些變化形式取決于工件或刀具的類型。儺恃舟汆覯柜鎳閔服把能皚周銑竿闞蠡瞢觸汞氅炱狗鬮攴黼在周銑（有時(shí)也叫平面銑削）中，由位于銑刀主體外周上的尺或刀片銑削的面一般在一個(gè)與銑刀軸平行的平面上。使用鏟齒銑刀和成形銑刀完成的銑削工序包括在這一類。銑削面的界面與所使用的銑刀或刀具組合的輪廓線或輪廓相符。芏覓忽京殄位鏌帛嵋忤斡看周銑作業(yè)通常在帶有水平定位主軸的銑床上進(jìn)行。但也可以在帶有端面銑刀的主軸銑床上進(jìn)行。銑刀安裝在心軸上，尤其是由于設(shè)置的條件，銑刀或者若干銑刀位于距主軸前端一定距離處時(shí)，心軸一般在外端得到支撐來提高剛性。如果部件可以端銑，一般不應(yīng)進(jìn)行周銑。汨佗漉鹿炯艱籟膾髟蕙黨獍端

19、銑戢帙巒捎箸卯氫褙歷藩輯綺端銑在臥室銑床和立式銑床上進(jìn)行。由位于銑刀外周和端面的切削刃聯(lián)合銑削所形成的銑削面一般與銑刀軸成直角。除了在肩部銑削時(shí)外，銑削面是平的，與齒的輪廓形狀無關(guān)。一般講，無論何時(shí)何地，只要可能就應(yīng)使用端銑。通卮薺嘹齊冽饒嘹屨康狼峨傳統(tǒng)（上）端銑中鐵屑厚度是變化的，在銑刀齒進(jìn)入和退出處最薄，而在沿水平直徑處最大。銑削面由齒和專署轉(zhuǎn)速痕跡表現(xiàn)其特征，這與周銑銑刀情況相同。這些痕跡的起伏度由齒的端面切削刃的磨削 精度或由刀體/刀片在可以指標(biāo)化的刀具內(nèi)組合精度以及刀具安裝精度來控制，以使刀具在主軸上精確運(yùn)動(dòng)。起伏度還有機(jī)器及工件本身的剛性來控制。當(dāng)端面切削刃的長(zhǎng)度短于每轉(zhuǎn)的進(jìn)給量（

20、或銑刀每轉(zhuǎn)一圈工件的移動(dòng)量）時(shí)，在銑面上就會(huì)形成一系列的環(huán)形凹槽或環(huán)紋。當(dāng)后齒在工件的銑面上拖動(dòng)時(shí)，也會(huì)產(chǎn)生類似的標(biāo)記。這叫齒根拖動(dòng)。攖篙懈鵯寄徠癃焚匾膛墻搿在端銑中，如果想獲得最佳結(jié)果，重要的是選擇銑刀具有適于所建議的切削寬度的直徑。如果可能，應(yīng)避免切削寬度等與銑刀外徑，因?yàn)樵邶X的入口處，薄的銑屑界面會(huì)由于研磨加上銑屑有焊或粘到齒或刀片上并被帶來帶去或再次切削的趨向而導(dǎo)致齒的加速磨損。這對(duì)表面光潔度是有害的。好的銑刀直徑與工件或提議的切削路線寬度之比是5：3。該仔娣廟膝憊避妥蜥顴虱吆酞饜酶匱胯撓淇逑掘巡煙算僂惺鏇刪奄鷚神色鹿殊稆鶇乓賭蹭遺窗膺蝸迎心被問甬棲痞膠崞窶雌坎麼哇帥嘍貼 Basic

21、Machining OperationsTurning, Boring and Milling涎瓜監(jiān)殆囈諍慚擤酌韉踞郝Basic Machining Operations景翱體邳甲諮坎鈐騅蒴欲豳M(fèi)achining tools have evolved from the early foot powered lathe Egyptians and John Wilkinsons boring mill. They are designed to provide rigid support for both the workpiece and the cutting tool and cuttin

22、g tool and can precisely control their relative positions and the velocity of the tool with respect to the workpiece. Basically, in metal cutting, a sharpened wedge-shaped tool removes a rather narrow strip of metal from the surface of a ductile workpiece in the from of a severely deformed chip. The

23、 chip is waste product that is workpiece in the from of a severely deformed chip is a waste product that is considerably shorter than the workpiece from which it came but with a corresponding increase in thickness of the uncut chip. The geometrical shape of the machine surface depends on the shape o

24、f the tool and its path during the machining opration. 萌百戎甍雩郾薨窿纜鍰淪拮 Most machine operations produce parts of differing geometry. If a rough cylindrical workpiece revolves about a central axis and tool penetrates beneath its surface and travels parallel to the center of rotation, a surface of revolut

25、ion is produced, and the operation is called turning. If a hollow tube is on the machined on the inside in a similar manner, the operation is called boring. Producing an external conical surface of uniformly varying diameter is called taper turning. If the tool point travels in a path of varying rad

26、ius, a contoured surface like that of bowling pin can be produced; or, if the piece is short enough and the support is sufficiently rigid, a contoured surface could be produced by feeding a shaped tool normal to the axis of rotation. Short tapered or cylindrical surfaces could also be contour formed

27、.光嗆羧遨紉貉沔訐兢導(dǎo)烙韋 Flat or plane surface are frequently required. They can be generated by radial turning or facing, in which the tool point moves normal to the axis of rotation. In other cases, it is more convenient to hole the workpiece steady and reciprocate the tool across , it is series of straight-

28、line cuts with a crosswise feed increment before each cutting stroke. This operation is called planning and is carried out on a shaper. For larger pieces it is easier to keep the tool stationary and draw the workpiece under it as in planning. The tool is fed at each reciprocation. Contoured surfaces

29、 can be produced by using shaped tools.粥溷瞿鄹傅锏鉛瘢嗝詰噠直 Multiple-edged tools can also be used. Drilling uses a twin-edged fluted tool for holes with depths up to 5 to 10 times the drill diameter. Whether the drill turns or the workpiece rotates, relative motion between the cutting edge and the workpiece

30、 is the important factor. In milling operations a rotary cutter with a number of cutting edges engages the workpiece, which moves slowly with respect to the cutter. Plane or contoured surfaces may be produced, depending on the geometry of the cutter and the type of feed. Horizontal or vertical axes

31、of rotation may be used, and the feed of the work piece may be in any of the three coordinate directions.儺林多兩翰縵崽鍥幸獠鞫垌Basic Machine Tools賞踣磚鵓釤酋鋌炳蛔鹱曳衽Machine tools are used to part of a specified geometetrical shape and precise size by removing metal from a ductile material in the form chips. The latt

32、er are a waste product and vary from long continuous ribbons of a disposal point of view, to easily handed well-broken chips resulting from cast iron. Machine tools perform five basic metal-remove processes: turning, planning, drilling, milling, and grinding. All other metal-removal processes are mo

33、difications of these five basic processes. For example, boring is internal turning; reaming, tapping, and counter boring mollify drilled holes and are related to drilling; hobbling and gear cutting are fundamentally milling operations; hack sawing and broaching are a from of planning and honing; lap

34、ping, super finishing, polishing, and buffing are variants of grinding or abrasive removal operations. Therefore, there are only four types of basic machine tools, which use cutting tools of specific controllable geometry. The grinding process forms chips, but the geometry of the abrasive grain is u

35、ncontrollable.萜蕾櫳鄭米嘎趑擰遽矩英筠The amount and rate of material removed by the various machining processes may be large, as in heavy turning operations, or extremely small, as in lapping or superfinishing operations where only the high spots of a surface are removed.笈啻輯踢緬袱鑫碟本輕舂曖A machining tool performs t

36、hree major functions: 1. it rigidly supports the workpice or its holder and the cutting tool; 2. it provides relative motion between the workpice and the cutting tool; 3. it provides a range of feeds and speeds usually ranging from 4 to32 choices in each case.逖昶聳穰餼心磊套磺敞放蝙Speed and Feeds in Machining

37、 暌?guī)浤请睦邶r鑒蔣烹堀縈堆 Speeds, feeds, and depth pf cut are the three major variables for economical machining. Other variables are the work and tool materials, coolant and geometry of the cutting tool. The rate of metal removal and power required for machining depend upon these variables.棟歲甌瞼繾趾瘤慢洇凱薊慰The dept

38、hs of cut, feed, and cutting speed are machine setting that must be established in any metal-cutting operation. They all affect the forces, the power, and the rate of metal removal. They can be defined by comparing them to the needle and record of a phonograph. The cutting speed (V) is represented b

39、y the velocity of the record surface relative to the needle in the tone arm at any instant. Feed is represented by the advance of the needle radially inward per revolution, or is the difference in position between two adjacent grooves. The depth of cut is the penetration of the needle into the recor

40、d or the depth of the grooves.適粼褸禱咪鳥契曛鑲虛減趵Turning on lathe centers渡顥憔蟹澉州潭粒狹紺橢魔The basic operations operations performed on an engine lathe are illustrated in fig. 11-3. those operations performed on external surfaces with a single point cutting tool are called turning. Except for drilling, reaming,

41、and tapping, the operations on internal surfaces are also performed by a single point cutting tool.熒拘弄越雋駝網(wǎng)赳甘鮮沏棄All machining operate, including turning and boring, can be classified as roughing, finishing, or semi-finishing. The objective of a roughing operation is to remove the bulk of the material

42、 as rapidly and as efficiently as possible, while leaving a small amount of material on the work-piece for the finishing operation. Finishing operations are performed to obtain the final size, shape, and surface finish on the workpiece. Sometimes a semi-finishing operation will precede the finishing

43、 operation to leave a small predetermined and uniform amount of stock on the work-piece to be removed by the finishing operation.癟栓醅炕羨齟漶巰隅贓埭謝 Generally, longer workpieces are turned while supported on one or two lathe centers. Cone shaped holes, called center holes, which fit the lathe centers are d

44、rilled in the end of the workpiece-usually along the axis of the cylindrical part. The end of the workpiece adjacent to the tailstock is always supported by a tailstock center, while end near the headstock may be supported by a headstock center or held in a chuck. The headstock end of the workpiece

45、may be held in a four-jaw chuck, or in a collet type chuck. This method holds the workpiece firmly and transfers the power to the workpiece smoothly; the additional support to the workpiece provided by the chuck lessens the tendency for chatter to occur when cutting. Precise result can be obtained w

46、ith this method if care is taken to hold the workpiece accurately in the chuck.逐酮們糌庖汲登破筇雜源仳Very precise results can be obtained by supporting the workpiece between two centers. A lathe dog is clamped to the workpiece; together they are driven by the driver plate mounted on the spindle nose. One end

47、of the workpiece is machined; then the workpiece can be turned around in the lathe to machine to other end. The center holes in the workpiece serve as precise locating surfaces as well as bearing surfaces to carry the weight of the workpiece and to resist the cutting forces. After the workpiece has

48、been remove from the lathe for any reason, the center holes will accurately align the workpiece back in the lathe or in another lathe, or in a cylindrical grinding machine. The workpiece must never be held at the headstock end by both a chuck and a lathe center. While at first thought this seems lik

49、e a quick method of aligning the workpiece in the chuck, this must not be done because it is not possible to press evenly with the jaws against the workpiece while it is also supported by the center. The alignment provided by the center will not be maintained and the pressure of the jaws may damage

50、the center hole, the lathe center, and perhaps even the lathe spindle. Compensating or floating jaw chucks used almost exclusively on high production work provide an exception to the statements made above. These chucks are really work drivers and cannot be used for the same purpose as ordinary three

51、 or four-jaw chicks.澤筒畸具習(xí)憾襯磉咩倩御怠While very large diameter workpiece are sometimes mounted on two centers, they are preferably held at the headstock end by faceplate jaws to obtain the smooth power transmission; moreover, large lathe dogs that are adequate to transmit the power not generally availabl

52、e, although they can be made as a special. Faceplate jaws are like chuck jaws except that they are mounted on a faceplate, which has less overhang from the spindle bearings than a large chuck would have.匏級(jí)吣問踺專蘢鐒汩邶吡秘Boring氪笊丕薦蠛弛情護(hù)馨嚌惴紜The objective of boring a hole in a lathe is:躓籽塄呤置鮚搬怒汞騶摞弒1. To enla

53、rge the hole 葳肋效賊牟資鱗等智堆鈀械2. To machine the hole to the desired diameter圭纟榮輪敢缽非鰍驅(qū)貝崆歧3. To accurately locate the position of the hole 櫬嚆斡勘伸柿耗喳為敉僳林4. To obtain a smooth surface finish in the hole窗鵯跆諗廛踝肅盼逵蛺史烤The motion of the boring tool is parallel to the axis of the lathe when the carriage is moved in

54、 the longitudinal direction and the work piece revolves about the axis of the lathe. When these two motions are combined to bore a hole, it will be concentric with the axis of rotation of the lathe. The position of the hole can be accurately located by holding the work piece in the lathe so that the

55、 axis about which the hole is to be machined coincides with the axis of rotation of the lathe. When the boring operation is done in the same setup of the work that is used to turn and face it, practically perfect concentricity and perpendicularity can be achieved.籟煲綽攏崤刑樣綾趟饞蔡回The boring tool is held

56、in a boring bar which is fed through the hole by carriage. Variations of this design are used, depending on the job to be done. The lead angle used, if any, should always be small. Also, the nose radius of the boring tool must not be too large. The cutting speed used for boring can be equal to the s

57、peed for turning. However, when the spindle speed of the lathe is calculated, the finished, or largest, bore diameter should be used. The feed rate for boring is usually somewhat less than for turning to compensate for the rigidity of the boring bar.碚圇醉奕瓦預(yù)齪倍賠彗鏊茆The boring operation is generally perf

58、ormed in two steps; namely, rough boring and finish boring. The objective of the rough-boring operation is to remove the excess metal rapidly and efficiently, and the objective of the finish-boring operation is to obtain the desired size, surface finish, and location of the hole. The size of the hol

59、e is obtained by using the trial-cut procedure. The diameter of the hole can be measured with inside calipers and outside micrometer calipers. Basic Measuring Instrument, or inside micrometer calipers can be used to measure the diameter directly.頸科鳧颼似碲芤也妓迎暇措 Cored holes and drilled holes are sometimes eccentric with respect to the rotation of the l