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南 京 理 工 大 學(xué) 紫 金 學(xué) 院
畢業(yè)設(shè)計(論文)外文資料翻譯
系 ： 機械工程系
專 業(yè)： 機械工程及自動化
姓 名：
學(xué) 號：
(用外文寫)
外文出處： Journal of Manufacturing Science
and Engineering
附 件： 1.外文資料翻譯譯文；2.外文原文。
指導(dǎo)教師評語：
通過指導(dǎo)該生對翻譯進行多次修改以后，該翻譯語句比較正確，全文能夠較好地忠實于原文原意，全文格式正確，用詞恰當(dāng)，全文的翻譯的工作量符合學(xué)生規(guī)定的基本要求，圖表表達正確，是一篇較好的外文翻譯。綜合評定為良好。
簽名：
2010年 3 月 25日
附件1：外文資料翻譯譯文
數(shù)控機床
Outrata, J. and Jowe, J.
雖然數(shù)控機床的具體用途和應(yīng)用不盡相同，但所有形式的數(shù)控系統(tǒng)都有共同的優(yōu)點。這里有一些數(shù)控裝備提供的更加重要的好處：
第一個優(yōu)點是所有的數(shù)控機床被改進成自動化。操作員可以減少或消除對生產(chǎn)工件的干預(yù)。許多數(shù)控機床可以自動運行整個加工循環(huán)，而讓操作員做其他的工作。這給數(shù)控機床用戶帶來了幾方面的好處包括減少操作人員的疲勞、減少人為所犯的錯誤、可以預(yù)測每個工件的加工時間等。由于機器是在程序控制下運行，降低了數(shù)控機床操作員傳統(tǒng)機械加工要求（機械加工的基本做法）。
第二個優(yōu)點是一致性和準確性?，F(xiàn)在的數(shù)控機床擁有令人難以置信的準確性和可重復(fù)性。這意味著一旦一個程序被確認，那么兩個、十個或一千個相同的工件可以很容易地達到規(guī)定精度并保持一致性。
第三個優(yōu)點是由數(shù)控系統(tǒng)最靈活的形式提供的。由于數(shù)控機床運行的是程序，所以加工不同的零件和加載不同的程序都很簡單。一旦一個程序確認被用來加工零件后，下一次要再加工同樣零件時就很容易拿來運用。這就會產(chǎn)生另外一個好處。由于這些設(shè)備非常容易設(shè)置和運行，所以它們可以用很短的時間進行設(shè)置，使程序很容易的被加載。這對現(xiàn)在的實時（JIT）的產(chǎn)品需求是非常有必要的。
運動控制—數(shù)控的核心
任何數(shù)控機床最基本的功能是自動的、精確的、一致的運動控制。而不像多數(shù)常規(guī)機床完全運用機械部件運動，數(shù)控機床的改革之處在于它用計算機控制。數(shù)控設(shè)備兩個或兩個以上的方向運動的形式，稱為軸。這些軸可以用來精確定位和自動沿規(guī)定長度行走。兩個最常見的類型是線性軸（驅(qū)動沿直線路徑）和旋轉(zhuǎn)軸（沿圓形軌跡驅(qū)動）。
與傳統(tǒng)機床加工中的由曲柄和手輪組成的加工工序相比較，數(shù)控機床的加工工序是由程序控制的。一般來說，運動類型（快速，線性和圓形）、軸走動、運動量和運動速度（進給速度）都是用由程序來控制的。
在運行過程中數(shù)控命令告訴驅(qū)動馬達精確轉(zhuǎn)動的次數(shù)。反過來驅(qū)動馬達旋轉(zhuǎn)滾珠絲桿，而球螺桿驅(qū)動線性軸。反饋設(shè)備（線性比例在幻燈片）是用來確認是否有誤差。參照圖1.
圖1. 經(jīng)典的數(shù)控機床傳動系統(tǒng)
用一個比較簡單的類比，相同的基本直線運動可以在一個普通的老虎鉗上找到，當(dāng)你旋轉(zhuǎn)老虎鉗，絲桿旋轉(zhuǎn)，反過來，臺鉗上的驅(qū)動器也可移動老虎鉗下顎。相比之下，在數(shù)控機床直線軸是非常準確的。驅(qū)動電機的轉(zhuǎn)數(shù)精確地控制著軸直線運動的量。
如何控制多軸運動 - 理解坐標(biāo)系統(tǒng)
對于操作員來說，控制定量的直線運動時他是不可能告訴每個驅(qū)動電機旋轉(zhuǎn)多少次來驅(qū)動軸的。相反（這就像不得不搞清楚如何使老虎鉗的下顎精確的移動1英寸?。?，如果利用某種形式的坐標(biāo)系，那么所有的多軸運動將被更為簡單和合理的方式控制。數(shù)控機床最常用是直角坐標(biāo)系和極坐標(biāo)系。目前為止，這兩個中比較常用的是直角坐標(biāo)系。
在一個數(shù)控程序中程序零點是運動參考零點，這可以使程序員指定從一個共同的地點運動。如果零點被正確的選擇，那么程序采用的坐標(biāo)可以直接顯示出來。
利用這種技術(shù)，如果程序員想讓機床移動到零點右邊1英寸的地方，那么就輸入X 1.0，如果程序員想讓機床移動到零點上方1英寸的地方，那么就輸入Y 1.0。程序會自動控制驅(qū)動電機運轉(zhuǎn)多少次和滾珠絲桿，使軸到達目標(biāo)位置。這是程序員控制多軸運動非常常用的方式。參照圖2、圖3。
理解絕對與相對的概念
所有的討論集中于這一點，假設(shè)編程使用絕對模式。設(shè)置絕對模式最常用的指令是G90。在絕對模式下，所有程序運行終點都是以零點為起始點。對于初學(xué)者來說，運動指令開始通常最好的和最容易的方法是指定端點。但是，還有另一種指定的多軸運動結(jié)束點的方法。
圖2.從網(wǎng)格圖中觀察X.Y坐標(biāo) 圖3.X.Y和Z坐標(biāo)軸
在增量模式（通常指定G91）下，程序最終點的指定是從程序的當(dāng)前位置，而不是從程序的零點。用這樣的程序指令方法時，程序員必須時刻問：“我應(yīng)該如何移動機床？”雖然有些時候的增量模式，可以是非常有幫助，一般來說，這種指令模式對初學(xué)者來說更麻煩和困難，所以要集中使用絕對模式。
當(dāng)你做出運行指令時要小心，初學(xué)者要有增量的思維。如果工作在絕對模式（作為初學(xué)者應(yīng)該使用），程序員應(yīng)該想：“機床應(yīng)該移到那個點？”這個點是程序零點相關(guān)，與機床當(dāng)前位置無關(guān)。
對于任何命令除使它非常容易確定當(dāng)前位置之外，另一個好處是與工作在絕對方式下和在行動命令期間犯的錯誤有關(guān)。在絕對模式下，如果運行錯誤由于一個程序的命令導(dǎo)致，只有一個運動是不正確的。從另一方面說，如果錯誤是在增量運動模式下發(fā)生，那么從這一點開始，接下來所有的程序運行都是錯誤的。
分配程序零點
請記住，數(shù)控系統(tǒng)必須通過一種或多種方式告訴它零點的位置?？刂撇煌臋C床要做到這一點有很大的差異。一種(或一種以上)的方式是通過數(shù)控程序來設(shè)置的。使用這種方法，程序員要計算程序起始點到程序零點的距離。通常的做法是在程序起始和運行開始之前時用G92(或G50)指令設(shè)置。
另外，更新和更好的方法去設(shè)置程序零點是通過某種形式的偏移。請參照圖4，通常機床制造商通過利用分配偏移夾具來抵消程序零點誤差。制造商稱這種方式為利用程序零點分配每個機床的幾何偏移。
圖4.通過G54指令來設(shè)定系統(tǒng)零點
柔性制造單元
一個柔性制造單元（FMC）是一個柔性制造子系統(tǒng)。以下是柔性系統(tǒng)之間存在的差異：
1.一個柔性制造單元是由一個中央計算機直接控制的。相反，指令從中央電腦傳遞到單元控制器。
2. 該單元是整個系統(tǒng)的一部分。
柔性制造單元中通常包含以下單元：
. 單元控制器
. 可編程邏輯控制器（PLC）
. 多個個機床
. 一個材料處理設(shè)備（機器人或托盤）
高速機械加工
高速機械加工是指很高的加工速度和高的表面加工質(zhì)量。例如，具有非常高的材料去除率請參考圖5的切削參數(shù)名稱。在過去60年來，高速加工已經(jīng)應(yīng)用于金屬和非金屬等各種材料，包括表面加工質(zhì)量和用機器制造硬度50HRC以上的堅硬材料。大部分鋼鐵部件硬化程度非常高，大約32-42HRC。
圖5.切割數(shù)據(jù)
在粗加工和半精加工時，用電極加工和電火花加工硬度為63HRC的材料(特別是在加工小半徑和金屬切削難加工到的深孔)。在精加工和超精加工時表面適當(dāng)添加些硬質(zhì)合金、金屬陶瓷、整體硬質(zhì)合金、混合陶瓷或聚晶立方氮化硼（PCBN）。
對于許多組件，生產(chǎn)過程中都需要涉及到這些加工方式，在模具生產(chǎn)時還包括費時的手工拋光。因此，會導(dǎo)致生產(chǎn)成本過高。
這是個典型的模具生產(chǎn)環(huán)節(jié)或只是一些相同的設(shè)計工具。這一過程涉及到設(shè)計的不斷變化，由于這些變化也可用于測量和逆向工程相應(yīng)的需要中。
模具的質(zhì)量水平高低的主要標(biāo)準是三維幾何精度和表面準確性。如果加工后的質(zhì)量低不能滿足要求，將消耗許多的人工去彌補。而高速機械加工能產(chǎn)生令人滿意的表面精度，但它會產(chǎn)生尺寸和幾何精度誤差。
模具工業(yè)發(fā)展的主要目標(biāo)之一是，減少或消除手工拋光的需要，從而提高質(zhì)量，減少了生產(chǎn)成本和交貨時間。
經(jīng)濟和技術(shù)因素為高速加工的發(fā)展提供了基礎(chǔ)。
生存
市場競爭的不斷加劇也樹立了新的標(biāo)準。它對時間和成本效率的要求越來越高。這使新的工藝和生產(chǎn)技術(shù)的發(fā)展得以進行。高速加工提供為此希望和解決辦法。
材料
新的、更難加工的材料要求我們必須發(fā)展去尋找新的加工方案。航空航天工業(yè)有耐熱合金和不銹鋼；汽車行業(yè)有不同的雙金屬成分，緊湊型石墨鐵和鋁的成分不斷增加；模具工業(yè)的主要面對硬質(zhì)材料粗加工到精加工的問題。
質(zhì)量
持續(xù)競爭的結(jié)果是提高了產(chǎn)品的結(jié)構(gòu)和質(zhì)量。如果能正確使用高速加工，就能解決這方面的一些問題。代替手工精加工就是一個很好的例子，特別是在加工精密模具和復(fù)雜三維幾何體時。
過程
在這個快速和高效的時代要求下，簡化流程（物流）大多數(shù)時候可以用高速加工來解決。在模具和模具工業(yè)中典型的例子就是用設(shè)定好的機器去制造難加工的工具。隨著高速切削加工的應(yīng)用，昂貴和費時的電火花加工過程也可以減少或被消除。
設(shè)計與開發(fā)
現(xiàn)代產(chǎn)品競爭的主要方法之一就是創(chuàng)新的設(shè)計。今天產(chǎn)品的平均生命周期是汽車4年，電腦及配件1.5年，手機3個月...設(shè)計快速的發(fā)展和減少產(chǎn)品開發(fā)時間的先決條件是高速加工技術(shù)。
復(fù)雜的產(chǎn)品
一個有多個加工表面的部件，如為渦輪葉片設(shè)計新的優(yōu)化功能和特性。早期的設(shè)計允許利用手或機器人進行拋光。新的、更加復(fù)雜的渦輪葉片的設(shè)計和加工必須都通過高速加工?，F(xiàn)在有越來越多的薄壁工件需要用機器來加工如（醫(yī)療設(shè)備，電子，國防產(chǎn)品，電腦配件）。
生產(chǎn)設(shè)備
大力發(fā)展切削材料，夾具，機床和數(shù)控系統(tǒng)，特別是CAD/CAM功能和設(shè)備。必須以開放的思想去接受新的生產(chǎn)方式和技術(shù)。
高速加工的定義
所羅門的理論，1931年德國對機械高速切削的定義為：假定“在某個切削速度（是傳統(tǒng)機械加工的5-10倍），排屑時切削刃的溫度將減少?！眳⒁妶D6.
所以給出結(jié)論:“需提供一個機會以提高加工生產(chǎn)效率相對傳統(tǒng)切割工具”。
在切削不同材料時切口溫度相對減少，不幸的是現(xiàn)代研究未能完全證實這一理論。
溫度對于鋼鐵和鑄鐵是逐漸變小的，但對于鋁和有色金屬是增大的。所以高速加工的定義必須基于其他因素。
鑒于目前的技術(shù)，“高速”概念普遍平均速度是1至10公里每分鐘，約3 300至33 000英尺每分鐘。速度超過10公里/分鐘是超高速，大部分用在金屬切削實驗領(lǐng)域。顯然，要實現(xiàn)工件表面的切割速度，主軸旋轉(zhuǎn)速度直接與工件的直徑有關(guān)?，F(xiàn)在一個很明顯的趨勢就是運用大直徑刀具，這對模具設(shè)計有重要意義。
圖6. 芯片根據(jù)切割速度控制溫度
有許多不同的觀點和不同的方法來定義高速加工。
維護保養(yǎng)和故障排除
維修管理成員
下面是一個需要定期保養(yǎng)的臥式加工中心的名單，如圖7所示。列出的是工作頻率、需要的電流的容量和類型。必須遵循這些要求，以保持您的機器有良好的工作秩序，同時也使保修安全。
圖7.臥式加工中心
每天要做的事情
頂部冷卻水每8小時換一次（尤其在重型機床上要特別注意）
檢查機油潤滑的位置
從封口利用最佳方法清潔芯片
從換刀處清潔芯片
主軸錐度要擦拭干凈
每周要做的事情
請檢查過濾減壓閥自動排水是否正常運作。見圖。 8
圖8.潤滑和氣動方式
在處理TSC機型時，要清洗儲存冷卻液的罐子。
打開油箱蓋和去除油箱內(nèi)的所有沉積物。斷開冷卻泵之前，要小心控制冷卻液并切斷電源。除了TSC機型每個月都做做這個工作。
檢查空氣壓力/安全為85 psi。
為了與TSC機型相匹配，應(yīng)該把潤滑油放在法蘭邊緣。除了TSC機型每個月都做這個工作。
清潔機器表面要溫和清潔。不要使用溶劑。
根據(jù)機器的規(guī)格檢查液壓平衡壓力。
用手指涂抹油脂或工具對對刀邊緣潤滑。
每月要做的事
檢查變速箱機油的水平。添加機油，直到油開始從廢油管出口流出。
清理托盤底部的清潔墊。
清潔定位軸和負載箱時需要拆除托盤。
如果有必要請檢查正常運行的方式和輕質(zhì)潤滑油。
每半年要做的事
更換冷卻劑和徹底清洗水箱中的冷卻劑。
檢查所有的軟管和潤滑線路是否堵塞。
每年要做的事
更換變速箱油。從變速箱油排除廢油，然后慢慢填充2夸脫美孚DTE 25油。
檢查潤滑油過濾器并清除過濾器底部殘渣。
每2年更換控制箱中的空氣過濾器。
礦物乳化油將損壞在機器中的橡膠成分。
疑難解答
本節(jié)的目的是解決使用過程中已知的問題。給出的解決方案是為了給個人提
供開放式CNC模式服務(wù)，首先，確定問題的來源，第二，解決問題。
利用常識
許多問題通過正確的評估很容易得到解決。所有的機器都是由程序，機身與
工作部件構(gòu)成。遇到故障時你必須檢查這三個部分中的任何一個。不要指望機器能過改正由于一個小縫隙而導(dǎo)致的桿抖動。
不要懷疑機床的準確性在臺鉗彎曲的部分。如果你不首先中心鉆孔那么孔的中心定位就達不到要求。
首先發(fā)現(xiàn)問題
許多技工在搞清問題之前把事情搞砸了，所以他們希望回到過去。我們所知道的事實是，超過一半的零件修理之后仍能保持良好的工作狀態(tài)。如果主軸不轉(zhuǎn)，記住，主軸連接到齒輪箱，它是由主軸驅(qū)動器連接到主軸電機，它連接到I / O板，這是都是由處理器驅(qū)動。如果傳送帶是壞的，那么它就不能為主驅(qū)動器傳動。首先發(fā)現(xiàn)問題，不要去只想到簡單的問題。
不要擺弄機器
你可以在機器上更改參數(shù)，電線和開關(guān)等。不要隨意更改啟動部件和參數(shù)。記住，如果你想更改什么，但沒有正確改動那么你會弄壞其他東西。認真考慮改變處理器參數(shù)的時間。首先，你必須下載所有參數(shù)，刪除12個連接器，取代主機，重新連接并重新加載，如果你犯了一個錯誤那么它將無法工作。不管什么時候你在操作機器時你都應(yīng)該考慮可能發(fā)生意外會使機器損壞。檢查你認為有問題的部位，這是個廉價的保險措施。機器工作越好那么你做的工作就越少。
附件2：外文原文（復(fù)印件）
CNC machine tools
Outrata, J. and Jowe, J.
While the specific intention and application for CNC machines vary from one machine type to another, all forms of CNC have common benefits. Here are but a few of the more important benefits offered by CNC equipment.
The first benefit offered by all forms of CNC machine tools is improved automation.
The operator intervention related to producing workpieces can be reduced or eliminated.Many CNC machines can run unattended during their entire machining cycle, freeing the operator to do other tasks. This gives the CNC user several side benefits including reduced operator fatigue, fewer mistakes caused by human error, and consistent and predictable machining time for each workpiece. Since the machine will be running under program control, the skill level required of the CNC operator (related to basic machining practice) is also reduced as compared to a machinist producing workpieces with conventional machine tools.
The second major benefit of CNC technology is consistent and accurate workpieces.Today's CNC machines boast almost unbelievable accuracy and repeatability specifications. This means that once a program is verified, two, ten, or one thousand identical workpieces can be easily produced with precision and consistency.
A third benefit offered by most forms of CNC machine tools is flexibility. Since these machines are run from programs, running a different workpiece is almost as easy as loading a different program. Once a program has been verified and executed for one production run, it can be easily recalled the next time the workpiece is to be run. This leads to yet another benefit, fast change over. Since these machines are very easy to set up and run, and since programs can be easily loaded, they allow very short setup time.
This is imperative with today's just-in-time (JIT) product requirements.
Motion control - the heart of CNC
The most basic function of any CNC machine is automatic, precise, and consistent motion control. Rather than applying completely mechanical devices to cause motion as is required on most conventional machine tools, CNC machines allow motion control in a
revolutionary manner2. All forms of CNC equipment have two or more directions of motion,called axes. These axes can be precisely and automatically positioned along their lengths of travel. The two most common axis types are linear (driven along a straight path) and rotary (driven along a circular path).
Instead of causing motion by turning cranks and handwheels as is required on conventional machine tools, CNC machines allow motions to be commanded through programmed commands. Generally speaking, the motion type (rapid, linear, and circular),the axes to move, the amount of motion and the motion rate (feedrate) are programmable with almost all CNC machine tools.
A CNC command executed within the control tells the drive motor to rotate a precise number of times. The rotation of the drive motor in turn rotates the ball screw. And the ball screw drives the linear axis (slide). A feedback device (linear scale) on the slide allows the control to confirm that the commanded number of rotations has taken place3. Refer to fig.1.
Though a rather crude analogy, the same basic linear motion can be found on a common table vise. As you rotate the vise crank, you rotate a lead screw that, in turn,drives the movable jaw on the vise. By comparison, a linear axis on a CNC machine tool is extremely precise. The number of revolutions of the axis drive motor precisely controls the amount of linear motion along the axis.
How axis motion is commanded - understanding coordinate systems
It would be infeasible for the CNC user to cause axis motion by trying to tell each axis drive motor how many times to rotate in order to command a given linear motion amount4.(This would be like having to figure out how many turns of the handle on a table vise will cause the movable jaw to move exactly one inch!) Instead, all CNC controls allow axis motion to be commanded in a much simpler and more logical way by utilizing some form
of coordinate system. The two most popular coordinate systems used with CNC machines are the rectangular coordinate system and the polar coordinate system. By far, the more popular of these two is the rectangular coordinate system.
The program zero point establishes the point of reference for motion commands in a CNC program. This allows the programmer to specify movements from a common location. If program zero is chosen wisely, usually coordinates needed for the program can be taken directly from the print.
With this technique, if the programmer wishes the tool to be sent to a position one inch to the right of the program zero point, X1.0 is commanded. If the programmer wishes the tool to move to a position one inch above the program zero point, Y1.0 is commanded. The control will automatically determine how many times to rotate each axis drive motor and ball screw to make the axis reach the commanded destination point. This lets the programmer command axis motion in a very logical manner. Refer to fig.2, 3.
Understanding absolute versus incremental motion
All discussions to this point assume that the absolute mode of programming is used6.The most common CNC word used to designate the absolute mode is G90. In the absolute mode, the end points for all motions will be specified from the program zero point. For beginners, this is usually the best and easiest method of specifying end points for motion commands. However, there is another way of specifying end points for axis motion.
In the incremental mode (commonly specified by G91), end points for motions are specified from the tool's current position, not from program zero. With this method of commanding motion, the programmer must always be asking "How far should I move the tool?" While there are times when the incremental mode can be very helpful, generally speaking, this is the more cumbersome and difficult method of specifying motion and beginners should concentrate on using the absolute mode.
Be careful when making motion commands. Beginners have the tendency to think incrementally. If working in the absolute mode (as beginners should), the programmer should always be asking "To what position should the tool be moved?" This position is relative to program zero, NOT from the tools current position.
Aside from making it very easy to determine the current position for any command, another benefit of working in the absolute mode has to do with mistakes made during motion commands. In the absolute mode, if a motion mistake is made in one command of the program, only one movement will be incorrect. On the other hand, if a mistake is made during incremental movements, all motions from the point of the mistake will also be
incorrect.
Assigning program zero
Keep in mind that the CNC control must be told the location of the program zero point by one means or another. How this is done varies dramatically from one CNC machine and control to another8. One (older) method is to assign program zero in the program. With this method, the programmer tells the control how far it is from the program zero point to the starting position of the machine. This is commonly done with a G92 (or G50) command at least at the beginning of the program and possibly at the beginning of each tool.
Another, newer and better way to assign program zero is through some form of offset. Refer to fig.4. Commonly machining center control manufacturers call offsets used to assign program zero fixture offsets. Turning center manufacturers commonly call offsets used to assign program zero for each tool geometry offsets.
Flexible manufacturing cells
A flexible manufacturing cell (FMC) can be considered as a flexible manufacturing subsystem. The following differences exist between the FMC and the FMS:
1. An FMC is not under the direct control of the central computer. Instead, instructions from the central computer are passed to the cell controller.
2. The cell is limited in the number of part families it can manufacture.
The following elements are normally found in an FMC:
? Cell controller
? Programmable logic controller (PLC)
? More than one machine tool
? A materials handling device (robot or pallet) The FMC executes fixed machining operations with parts flowing sequentially between operations.
High speed machining
The term High Speed Machining (HSM) commonly refers to end milling at high rotational speeds and high surface feeds. For instance, the routing of pockets in aluminum airframe sections with a very high material removal rate1. Refer to fig.5 for the cutting data designations and for mulas. Over the past 60 years, HSM has been applied to a wide range of metallic and non-metallic workpiece materials, including the production of components with specific surface topography requirements and machining of materials
with hardness of 50 HRC and above. With most steel components hardened to approximately 32-42 HRC, machining options currently include:
rough machining and semi-finish l in its soft (annealed) condition
heat treatment to achieve the final required hardness = 63 HRC machining of electrodes and Electrical Discharge Machining (EDM) of specific parts of dies and moulds (specifically small radii and deep cavities with limited accessibility for metal cutting tools) finishing and super-finishing of cylindrical/flat/cavity surfaces with appropriate cemented carbide, cermet, solid carbide, mixed ceramic or polycrystalline cubic boron nitride (PCBN).
For many components, the production process involves a combination of these options and in the case of dies and moulds it also includes time consuming hand finishing .Consequently, production costs can be high and lead times excessive.
The main criteria is the quality level of the die or mould regarding dimensional geometric and surface accuracy. If the quality level after machining is poor and if it cannot meet the requirements, there will be a varying need of manual finishing work. This work produces satisfactory surface accuracy, but it always has a negative impact on the dimensional and geometric accuracy.
One of the main aims for the die and mould industry has been, and still is, to reduce Or eIiminate the need for manual polishing and thus improve the quality and shorten the production costs and lead times.
Survival
The ever increasing competition in the marketplace is continually setting new standards. The demands on time and cost efficiency is getting higher and higher. This has forced the development of new processes and production techniques to take place. HSM provides hope and solutions...
Materials
The development of new, more difficult to machine materials has underlined the necessity to find new machining solutions. The aerospace industry has its heat resistant and stainless steel alloys. The automotive industry has different bimetal compositions Compact Graphite Iron and an ever increasing volume of aluminum3. The die and mould industry mainly has to face the problem of machining high hardened tool steels, from roughing to finishing.
Processes
The demands on shorter throughput times via fewer setups and simplified flows
(logistics) can in most cases, be solved by HSM. A typical target within the die and mould industry is to completely machine fully hardened small sized tools in one setup. Costly and time consuming EDM processes can also be reduced or eliminated with HSM.
Design & development
One of the main tools in today's competition is to sell products on the value of novelty. The average product life cycle on cars today is 4 years, computers and accessories 1.5 years, hand phones 3 months... One of the prerequisites of this development of fast design changes and rapid product development time is the HSM technique.
Complex products
There is an increase of multi-functional surfaces on components, such as new design of turbine blades giving new and optimized functions and features. Earlier designs allowed polishing by hand or with robots (manipulators). Turbine blades with new, more sophisticated designs have to be finished via machining and preferably by HSM . There are also more and more examples of thin walled workpieces that have to be machined medical equipment, electronics, defence products, computer parts).
Production equipment
The strong development of cutting materials, holding tools, machine tools, controls And especially CAD/CAM features and equipment, has opened possibilities that must be met with new production methods and techniques5.
Definition of HSM
Salomon's theory, Machining with high cutting speeds..." on which, in 1931, took out A German patent, assumes that "at a certain cutting speed (5-10 times higher than in conventional machining), the chip removal temperature at the cutting edge will start to decrease...".See fig.6.
Given the conclusion:" ... seems to give a chance to improve productivity in machining with conventional tools at high cutting speeds..."
Modern research, unfortunately, has not been able to verify this theory totally. There Is a relative decrease of the temperature at the cutting edge that starts at certain cutting speeds for different materials.
The decrease is small for steel and cast iron. But larger for aluminum and other non-ferrous metals. The definition of HSM must be based on other factors.
Given today's technology, "high speed" is generally accepted to mean
Surface speeds between 1 and 10 kilometers perminute, or roughly 3 300 to 33 000 feet per minute. Speeds above 10 km/min are in the ultra-high speed category, and are largely the realm of experimental metal cutting. Obviously, the spindle rotations required to achieve these surface cutting speeds are directly related to the diameter of the tools being used.One trend which i