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文 獻 資 料 專 業(yè) 機械設計制造及其自動化 學 生 姓 名 張岳軍 班 級 BMZ 機制 031 學 號 0361440102 指 導 教 師 劉必榮 文 獻 資 料 1 咸斌 箱體類零件鉆鏜組合機床夾具 CAD 系統(tǒng) J 工具技術 2005 11 2 李春梅 崔鳳奎 組合機床 CAD 系統(tǒng) J 新技術新工藝 2004 10 3 李春梅 崔鳳奎 組合機床模塊化設計 CAD 系統(tǒng) J 機械工人 冷加工 2005 04 4 張滿囤 曹新國 林建平 組合機床總體方案 CAD 系統(tǒng)的設計與實現(xiàn) J 河 北工業(yè)大學學報 1999 04 5 吳樹青 夾具設計中的排屑問題 J 組合機床與自動化加工技術 1988 06 6 李春梅 崔鳳奎 組合機床模塊化設計 CAD 系統(tǒng) J 河南科技大學學報 自然 科學版 2004 05 7 佟璞瑋 戰(zhàn)略調(diào)整中的我國組合機床行業(yè) J 世界制造技術與裝備市場 1996 02 8 潘貴善 找準位置 突出重點 發(fā)展特色 振興行業(yè) 淺談 九五 組合機床 行業(yè)發(fā)展指導方針 J 組合機床與自動化加工技術 1996 01 9 裘愉 從幾個側(cè)面看組合機床的發(fā)展動向 J 組合機床與自動化加工技術 1994 11 10 羅文輝 組合機床在中小型工廠的應用 J 組合機床與自動化加工技術 1992 12 外 文 翻 譯 專 業(yè) 機械設計制造及自動化 學 生 姓 名 張 岳 軍 班 級 BMZ機制031 學 號 0361440102 指 導 教 師 劉 必 榮 外文資料名稱 MACHINE TOOLS 外文資料出處 Computer Aided Design 附 件 1 外文資料翻譯譯文 2 外文原文 指導教師評語 簽名 年 月 日 附件1 機 床 張岳軍譯 摘要 車床用于旋轉(zhuǎn)工件并從生成所需加工表面的所需方向進給切削刀具 最 常見的車床形式是以圖解方式顯示的六角車床 它由一個支撐床頭箱 拖板和 六角刀架的水平床身組成 工件夾在卡盤或夾頭中 或者安裝在機床主軸端部 的花盤上 關鍵字 機床 車床 機床基礎 許多情況下 初步進行成型加工出來的工件必須在尺寸和表面光潔度方面 進一步精整 以滿足它們的設計技術要求 為了滿足精密的公差 需要從工件 上去掉小量材料 通常機床就是用于這種加工的設備 在美國 材料切削業(yè)是一個很大的企業(yè) 費用每年超過36 109美元 包 括材料 勞動力 管理費 機床裝運費等所花的費用 由于60 機械和工業(yè)工 程以及技術等級評定工作都跟機械加工工業(yè)有某些關系 或者通過買賣 設計 或者機器車間中操作或在有關工業(yè)企業(yè)中加工 因此 對于工程專業(yè)學生來說 在他的學習計劃中集中一段時間去學習研究材料切削和機床 那是個好方法 機床通過切削工具去使工件成型以達到所需的尺寸提供了手段 機床通過 其基礎構件的功能作用 以控制相互關系方式支持 夾緊工具和工件 現(xiàn)將基 本部件列舉如下 a 床身 構架即機架 這是一個主要部件 該部件為主軸 拖板箱等提供 一個基礎和連接中介 在負載作用下 它必須使變形和振動保持最小 b 拖板箱和導軌 機床部件 如拖板箱 的移動 通常是在精確的導軌面 約束下靠直線運動來實現(xiàn) c 主軸和軸承 角位移是圍繞一個旋轉(zhuǎn)軸線發(fā)生的 該軸線的位置必須在 機床中極端精確的限度內(nèi)保持恒定 而且是靠精密的主軸和軸承來提供保證 d 動力裝置 電動機是為機床所普遍采用的動力裝置 通過對各個電機的 合適定位 使皮帶和齒輪傳動裝置減少到最少 e 傳動連桿機構 連桿機構是個通用術語 用來代表機械 液壓 氣動或 電動機構的 這些機構與確定的角位移和線性位移相關聯(lián) 加工工藝有兩個主要組成部分 a 粗加工工藝 粗加工 金屬切除率高 因而往往切削力也大 但所要求 的尺寸精度低 b 精加工工藝 精加工 金屬切除率低 因而往往切削力也小 但所要求 的尺寸精度和表面光潔度高 由此可見 靜載荷和動載荷 例如由不平衡的砂輪引起的動載荷 在精加 工中比粗加工中有著更為重要的意義 任何加工過程所獲得的精度通常將受到 由于力的作用引起發(fā)生的變形量的影響 機床座架一般是用鑄鐵制造的 然而有些也可能用鑄鋼或中碳鋼來制造 選用鑄鐵是因為它便宜 剛性好 受壓強度高 并且有減弱機床操作中產(chǎn)生的 振動的能力 為了避免床身鑄件碩大斷面 精心地設計筋條構架以便提供最大 的抗彎曲和抗扭轉(zhuǎn)應力的能力 筋條的兩種基本類型是 箱型結構和片狀斜支 撐式 箱型結構便于生產(chǎn) 箱壁上有孔口便于使型芯定位和取出 片狀斜支撐 筋條有較大的抗扭剛度亦能使截面上的碎屑掉落 它常常用于車床床身 機床 的拖板箱和導軌是支撐和引導彼此相對運動的零部件 通常是改變刀具相對于 工件的位置 運動一般以直線運動的方式 但也有時是轉(zhuǎn)動 例如對應于工件 的螺紋上的螺旋角方向而使萬能螺紋磨床上的砂輪頭轉(zhuǎn)動一個角度 拖板箱構 件的基本的幾何結構形狀是平的 V型槽形 燕尾槽形和圓柱形的 這些構件可 根據(jù)用途 以各種方法分別使用或結合使用 導軌的特性如下 a 運動精確 于此拖板是要按直線移動的 這直線必定是由兩個相互垂 直的平面形成而且拖板必定不存在轉(zhuǎn)動 機床導軌的直線度公差是每米0 0 02 毫米 在水平面上這個公差可以進行處理 以使得到凸形表面 這樣就抵消導 軌下凹的作用 b 調(diào)整手段 為了便于裝配 維護精度和在發(fā)生磨損后便于限制移動構 件之間的 竄動 有時在拖板內(nèi)裝入扁條 這扁條被叫做 鋃條 通常該 鋃條用穿過長孔的沉頭螺釘支住 而用平頭螺釘調(diào)整好后用鎖緊螺母上緊 c 潤滑 導軌可用以下兩種裝置進行潤滑 1 間歇潤滑 通過潤滑脂 嘴或油嘴進行 這是一種適于運動速度低而不頻繁場合的方法 2 連續(xù)潤滑 例如通過計量閥和管道將潤滑油泵送到潤滑點 用這種方法引入兩表面間的油 膜必定是很薄的 目的是避免使拖板 浮起 如果滑移表面似鏡面平滑 油 就會被擠出而導致表面粘貼 因而在實踐上 拖板滑移表面是用凹面砂輪的刃 進行磨削或進行刮研 兩種工藝都可產(chǎn)生微小的表面凹痕 它就成為存油凹陷 相配合的零件就不會處因 浮起 而發(fā)生分離 這樣使拖板確定保持接觸導軌 d 防護 為了維護導軌處于良好狀態(tài) 以下條件必須滿足 1 必須防 止外面物質(zhì) 如碎屑進入 具有某一形狀的導軌那是所期望的 在這種場合 是不可能進入雜物的 例如是倒V形的導軌時 那就不可能保存碎屑雜物在導軌 上 2 必須保存潤滑油 在垂直或傾斜的導軌面上使用的油要有粘性 那很重 要 為了這種使用目的已經(jīng)專門研制出多種有用的潤滑油 油的粘性也要保護 以免被切削液沖毀 3 必須用防護罩來防止意外的損壞 車床 一臺機床實現(xiàn)三個主要功能 1 牢固地支持工件或者刀架和刀具 2 在工件和刀具之間提供相對運動 3 提供一定的走刀和切削速度范圍 以去除切屑形式來加工金屬的機床一般被分為四大類 使用單點刀具切削 的機床 使用多點刀具切削的機床 使用隨機點刀具切削的機床 磨削 和考 慮用于特殊場合的機床 本質(zhì)上 使用單點刀具切削的機床包括 1 普通車床 2 塔式車床 3 仿形車床 4 單軸自動車床 5 多軸自動車床 6 牛頭刨床和 龍門刨床 7 鏜床 使用多點刀具切削的機床包括 1 鉆床 2 銑床 3 拉床 4 鋸床 5 齒輪切割機床 使用隨機點刀具切削的機床包括 1 外圓磨床 2 無心磨床 3 平面磨床 用特殊的方法進行金屬切削的機床包括 1 化學蝕刻銑削機床 2 電火花加工機床 3 超聲波加工機床 車床是借助于轉(zhuǎn)動的工件對著刀具來 切去金屬材料 以產(chǎn)生外圓柱面或內(nèi)圓柱面或錐形表面的 它借助端面切削也 普遍用于加工平面 在端面切削加工中 工件旋轉(zhuǎn) 而刀具作垂直于回轉(zhuǎn)軸線 方向移動 普通車床是基本的旋削機床 從這點出發(fā) 已經(jīng)研制出其他旋削機床 驅(qū) 動電機裝在床身基礎上并通過齒輪 皮帶相結合來驅(qū)動主軸 以提供每分鐘25 到1500轉(zhuǎn)的轉(zhuǎn)速 主軸是一根堅固的空心軸 裝在重型軸承之間 其前端用來 安裝驅(qū)動盤 花盤 以便把確定的運動傳到工件 該驅(qū)動盤可借助螺紋 凸輪鎖緊機構或借助一個螺紋墊圈和鍵固定在主軸 上 車床的床身是鑄鐵件 它提供精確的磨削的滑動表面 導軌 其上放有 拖板 該車床拖板是H型的鑄件 而刀具就安裝在拖板上的刀架上 溜板箱裝在 拖板前面 并裝有移動刀具的齒輪機構 而拖板順著導軌或橫過導軌以提供所 希望的刀具的運動 拖板上面的小刀架能使刀夾回轉(zhuǎn)所要求的任意角度 為使 刀具作線性運動 在小刀架上裝有手輪和絲桿 以手輪和使小刀架垂直于車床 導軌移動的絲桿來提供橫向進給 溜板箱中的齒輪系可為拖板沿著導軌和橫跨 導軌提供動力進給 進給箱齒輪將運動傳給拖板并控制刀具相對于工件的運動 速度 典型的車床進給范圍是主軸每轉(zhuǎn)從0 002到0 160英寸 大約有50級轉(zhuǎn)速 由于進給箱的移動運動是由主軸齒輪驅(qū)動的 因此進給量直接與主軸速度有關 進給箱齒輪傳動機構也用于加工螺紋并能加工每英寸4到224扣螺紋 進給箱和車床溜板箱之間的連結軸是光桿和絲桿 許多車床制造商把這兩 桿結合成一桿 實際上那就以精確的開支減少機器的費用 進給桿 光桿 用 于提供刀具的運動 它對于精確的工件和好的表面光潔度是很重要的 螺紋導 桿 絲桿 用于提供精確的 螺紋 導程 這對于螺紋切削是必需的 光桿是 通過摩擦離合器來驅(qū)動的 那樣在刀具切削超載情況下能夠打滑保護 這一安 全裝置不能裝在絲桿上 因為螺紋加工是不允許打滑的 由于螺紋全深很難一 次走刀加工完成 因此裝設一螺紋指示盤作為下幾次走刀加工時重新對刀用 車床裝有尾座 它具有一精確的軸 該軸有一錐孔 以便安裝鉆頭 鉆夾 鉸刀和車床頂針 尾座可以沿著車床導軌移動以適應工件的不同長度以及加工 錐體或錐形表面 轉(zhuǎn)塔車床基本上是具有某種附加特性的普通車床 提供作為半自動加工和 減少人工操作誤差的機會 轉(zhuǎn)塔車床的拖板設有T形槽以便在車床導軌兩端安裝 夾刀裝置 當轉(zhuǎn)塔轉(zhuǎn)入到合適位置時 要正確地裝設刀具以便進行切削 拖板 也裝設有自動停機裝置以便控制刀具行程和提供良好的切削的再生產(chǎn) 轉(zhuǎn)塔車 床的尾座是六角形結構 在六角頭中可以裝六把刀具 雖然裝刀和加工準備要 花大量時間 但轉(zhuǎn)塔車床一次裝刀以后無需熟練工人就可以連續(xù)地重復地操作 加工 直到刀具變鈍并需更換為止 這樣轉(zhuǎn)塔車床僅就生產(chǎn)工作在經(jīng)濟上是可 行的 合理的 于此 根據(jù)所制造零件的數(shù)量 為加工準備需要花一定數(shù)量的 時間那是合理的 無可非議的 跟蹤 重復加工車床裝有一個重復裝置以自動控制單點刀具縱向和橫向的 進給運動并可以一次或兩次走刀就生產(chǎn)出所需形狀和尺寸的光潔零件 單軸自動車床使用一個立式轉(zhuǎn)塔和兩個橫向溜板 工件通過機床主軸孔被 送入卡盤 而刀具是靠凸輪來自動操作控制 多軸自動車床裝有四 五 六或八根主軸 在每根主軸中裝一個工件 各 主軸圍繞著一根中心軸來轉(zhuǎn)換位置 以主刀具溜板去接近各主軸 每根軸位上 都裝有一側(cè)向可以獨立操作的刀具滑板 由于各刀具滑板都是靠凸輪操作的 因此加工準備可能花幾天時間 因而至少需要5000件的批量生產(chǎn) 它的使用才 是合理的 這種機床的主要優(yōu)點就是所有的刀具同時工作 因而一個工人可以 看管幾部機床 對于相對簡單的零件而言 多軸自動車床可以以每五秒鐘一件 的速度生產(chǎn)加工出成品來 附件2 MACHINE TOOLS Shigley J E Vicher J J Theory of machines and mechanisms New York MeGraw Hill Book Company 2000 Abstract Lathes are designed to rotate the workpiece and feed the cutting tool in the direction necessary to the required machined surface The most common form of lathe is the turret lathe it consists of a horizontal bed supporting the headstock the carriage and the turret The workpiece is gripped in a chuck or is mounted on a faceplate mounted on the end of the main spindle of the machine Keyword machine tools lathes Fundamentals of Machine Tools In many cases products from the primary forming processes must undergo further refinements in size and surface finish to meet their design specifications To meet such precise tolerances the removal of small amounts of material is needed Usually machine tools are used for such operation In the United States material removal is a big business in excess of 36 X 109 per year including material labor overhead and machine tool shipments is spent Since 60 percent of the mechanical and industrial engineering and technology graduates have something connection with the machining industry either through sale design or operation of machine shops or working in related industry it is wise for an engineering student to devote some time in his curriculum to studying material removal and machine tools A machine tool provides the means for cutting tools to shape a workpiece to required dimensions the machine supports the tool and the workpiece in a controlled relationship through the functioning of its basic members which are as follows a Bed Structure or Frame This is the main member which provides a basis for and a connection between the spindles and slides the distortion and vibration under load must be kept to a minimum b Slides and Slideways The translation of a machine element e g the slide is normally achieved by straight line motion under the constraint of accurate guiding surfaces the slideway c Spindles and Bearings Angular displacements take place about an axis of rotation the position of this axis must be constant within extremely fine limits in machine tools and is ensured by the provision of precision spindles and bearings d Power Unit The electric motor is the universally adopted power unit for machine tools By suitably positioning individual motors belt and gear transmissions are reduced to a minimum e Transmission Linkage Linkage is the general term used to denote the mechanical hydraulic pneumatic or electric mechanisms which connect angular and linear displacements in defined relationship There are two broad divisions of machining operations a Roughing for which the metal removal rate and consequently the cutting force is high but the required dimensional accuracy relatively low b Finishing for which the metal removal rate and consequently the cutting force is low but the required dimensional accuracy and surface finish relatively high It follows that static loads and dynamic loads such as result from an unbalanced grinding wheel are more significant in finishing operations than in roughing operations The degree of precision achieved in any machining process will usually be influenced by the magnitude of the deflections which occur as a result of the force acting Machine tool frames are generally made in cast iron although some may be steel casting or mild steel fabrications Cast iron is chosen because of its cheapness rigidity compressive strength and capacity for damping the vibrations set up in machine operations To avoid massive sections in castings carefully designed systems of ribbing are used to offer the maximum resistance to bending and torsional stresses Two basic types of ribbing are box and diagonal The box formation is convenient to produce apertures in walls permitting the positioning and extraction of cores Diagonal ribbing provides greater torsional stiffness and yet permits sward to fall between the sections it is frequently used for lathe beds The slides and slide ways of a machine tool locate and guide members which move relative to each other usually changing the position of the tool relative to the workpiece The movement generally takes the form of translation in a straight line but is sometimes angular rotation e g tilting the wheel head of a universal thread grinding machine to an angle corresponding with the helix angle of the workpiece thread The basic geometric elements of slides are flat vee dovetail and cylinder These elements may be used separately or combined in various ways according to the applications Features of slideways are as follows a Accuracy of Movement Where a slide is to be displaced in a straight line this line must lie in two mutually perpendicular planes and there must be no slide rotation The general tolerance for straightness of machine tool slideways is 0 0 02mm per 1000mm on horizontal surfaces this tolerance may be disposed so that a convex surface results thus countering the effect of sag of the slideway b Means of Adjustment To facilitate assembly maintain accuracy and eliminate play between sliding members after wear has taken place a strip is sometimes inserted in the slides This is called a gibstrip Usually the gib is retained by socket head screws passing through elongated slots and is adjusted by grub screws secured by lock nuts c Lubrication Slideways may be lubricated by either of the following systems 1 Intermittently through grease or oii nipples a method suitable where movements are infrequent and speed low 2 Continuously e g by pumping through a metering valve and pipe work to the point of application the film of oil introduced between surfaces by these means must be extremely thin to avoid the slide floating If sliding surfaces were optically flat oil would be squeezed out resulting in the surfaces sticking Hence in practice slide surfaces are either ground using the edge of a cup wheel or scraped Both processes produce minute surface depressions which retain pocket of oil and complete separation of the parts may not occur at all points positive location of the slides is thus retained d Protection To maintain slideways in good order the following conditions must be met 1 Ingress of foreign matter e g swarf must be prevented Where this is no possible it is desirable to have a form of slideway which does not retain swarf e g the inverted vee 2 Lubricating oil must be retained The adhesive property of oil for use on vertical or inclined slide surface is important oils are available which have been specially developed for this purpose The adhesiveness of oil also prevents it being washed away by cutting fluids 3 Accidental damage must be prevented by protective guards Lathes A machine tool performs three major functions 1 it rigidly supports the workpiece or its holder and the cutting tool 2 it provides relative motion between the workpiece and the cutting tool 3 it provides a range of feeds and speeds Machines used to remove metal in the form of chips are classified in four general groups those using single point tools those multipoint tools those using random point tools abrasive and those that are considered special Machines using basically the single point cutting tools include 1 engine lathes 2 turret lathes 3 tracing and duplicating lathes 4 single spindle automatic lathes 5 multi spindle automatic lathes 6 shapers and planers 7 boring machines Machines using multipoint cutting tools include 1 drilling machines 2 milling machines 3 broaching machines 4 sawing machines 5 gear cutting machines Machines using random point cutting tools include 1 cylindrical grinder 2 centreless grinders 3 surface grinders Special metal removal methods include 1 chemical milling 2 electrical discharge machining 3 ultrasonic machining The lathe removes material by rotating the workpiece against a cutter to produce external or internal cylindrical or conical surfaces It is also commonly used for the production of flat surfaces by facing in which the workpiece is rotated while the cutting tool is moved perpendicularly to the axis of rotation The engine lathe is the basic turning machine from which other turning machines have been developed The drive motor is located in the base and drives the spindle through a combination of belts and gears which provides the spindle speeds from 25 to 1500 rpm The spindle is a sturdy hollow shaft mounted between heavy duty bearings with the forward end used for mounting a drive plate to impart positive motion to the workpiece The drive plate may be fastened to the spindle by threads by a cam lock mechanism or by a threaded collar and key The lathe bed is cast iron and provides accurately ground sliding surfaces way on which the carriage rides The lathe carriage is a H shaped casting on which the cutting tool is mounted in a tool holder The apron hangs from the front of the carriage and contains the driving gears that move the tool and carnage along or across the way to provide the desired tool motion A compound rest located above the carriage provides for rotation of the tool holder through any desired angle A hand wheel and feed screw are provided on the compound rest for linear motions of the tool The cross feed is provided with a hand wheel and feed screw for moving the compound rest perpendicular to the lathe way A gear train in the apron provides power feed for the carriage both along and across the way The feed box contains gears to impart motion to the carriage and control the rate at which the tool moves relative to the workpiece On a typical lathe feeds range from 0 002 to 0 160 in per revolution of the spindle in about 50 steps Since the transmission in the feed box is driven from the spindle gears the feeds are directly related to the spindle speed The feed box gearing is also used in thread cutting and provides from 4 to 224 threads per in The connecting shaft between the feed box and the lathe apron are the feed rod and the lead screw Many lathe manufacturers combine these two rods in one a practice that reduces the cost of the machine at the expense of accuracy The feed rod is used to provide tool motion essential for accurate workpiece and good surface finishes The lead screw is used to provide the accurate lead necessary for the thread cutting The feed rod is driven through a friction clutch that allows slippage m case the tool is overloaded This safety device is not provided in the lead screw since thread cutting cannot tolerate slippage Since the full depth of the thread is seldom cut in one pass a chasing dial is provided to realign the tool for subsequent passes The lathe tailstock is fitted with an accurate spindle that has a tapered hole for mounting drills drill chucks reamers and lathe centers The tailstock can be moved along the lathe ways to accommodate various lengths of workpieces as well as to advance a tool into contact with the workpiece The tailstock can be offset relative to the lathe ways to cut tapers or conical surfaces The turret lathe is basically an engine lathe with certain additional features to provide for semiautomatic operation and to reduce the opportunity for human error The carriage of the turret lathe is provided with T slots for mounting a tool holding device on both sides of the lathe ways with tools properly set for cutting when rotated into position The carriage is also equipped with automatic stops that control the tool travel and provide good reproduction of cuts The tailstock of the turret lathe is of hexagonal design in which six tools can be mounted Although a large amount of time is consumed in setting up the tools and stops for operation the turret lathe once set can continue to duplicate operations with a minimum of operator skill until the tools become dulled and need replacing Thus the turret lathe is economically feasible only for production work where the amount of time necessary to prepare the machine for operation is justifiable in terms of the number of part to be made Tracing and duplicating lathes are equipped with a duplicating device to automatically control the longitudinal and cross feed motions of the single point cutting tool and provide a finished part of required shape and size in one or two passes of the tools The single spindle automatic lathe uses a vertical turret as well as two cross slides The work is fed through the machine spindle into the chuck and cams operate the tools automatically The multispindle automatic lathe is provided with four five six or eight spindles with one workpiece mounted in each spindle The spindles index around a central shaft with the main tool slide accessible to all spindles Each spindle position is provided with a side tool slide operated independently Since cams operate all of the slides the preparation of this machine may take several days and a production run of at least 5000 parts is needed to justify its use The principal advantage of this machine is that all tools work simultaneously and one operator can handle several machines For relatively simple parts multispindle automatic lathes can turn out finished products at the rate of 1 every 5 sec Shapers Drilling and Milling Machines A shapers utilizes a single point tool in a tool holder mounted on the end of the ram Cutting is generally done on the forward stroke The tool is lifted slightly by the clapper box to prevent excessive drag across the work which is fed under the tool during the return stroke in preparation for the next cut The column houses the operating mechanisms of the shaper and also serves as a mounting unit for the work supporting table The table can be moved in two directions mutually perpendicular lo the ram The tool slide is used to control the depth of cut and is manually fed It can be rotated through 90 deg on either side of its normal vertical position which allows feeding the tool at an angle to the surface of the table Two types of driving mechanisms for shapers are a modified Whitworth quick return mechanism and a hydraulic drive For the Whitworth mechanism the motor drives the hull gear which drives a crank arm with an adjustable crank pin to control the length of stroke As the bull gear rotates the rocker arm is forced to reciprocate imparting this motion to the shaper ram The motor on a hydraulic shaper is used only to drive the hydraulic pump The remainders of the shaper motions are controlled by the direction of the flow of the hydraulic oil The cutting stroke of the mechanically driven shaper uses 220 deg of rotation of the bull gear while the return stroke uses HO deg This gives a cutting stroke to return stroke ratio of 1 6 to 1 The velocity diagram shows that the velocity of the tool during the cutting stroke is never constant while the velocity diagram for a hydraulic shaper shows that for most of the cutting stroke the cutting speed is constant The hydraulic shaper has an added advantage of infinitely variable cutting speeds The principal disadvantage of this type of machine is the lack of a definite limit at the end of the ram stroke which may allow a few thousandths of an inch variation in stroke length A duplicating device that makes possible the reproduction of contours from a sheet metal template is available The sheet metal template is used in conjunction with hydraulic control Upright drilling machines or drill presses are available in a variety of sizes and types and arc equipped with a sufficient range of spindle speeds and automatic feeds to fit the needs of most industries Speed ranges on a typical machine are from 76 to 2025 rpm with drill feed from 0 002 to 0 020 in per revolution of the spindle Radial drilling machines are used to drill workpieces that are too large or cumbersome to conveniently move The spindle with the speed and teed changing mechanism is mounted on the radial arm by combining the movement of the radial arm around column and the movement of the spindle assembly al