【正文】 ns and were used when only positional accuracy was necessary. As an example of pointtopoint motion on a machine tool for drilling operations, the typical movement might be fast traverse of the work piece under the drill39。 conversational input is also called userfriendly or prompted input. Later in this section examples of each of these programming formats in machining applications will be describes. CAM and CNC CAM systems have changed the job of the CNC programmer from one manually producing CNC code to one maximizing the output of CNC machines. Since CNC machine tools are made by a great number of manufacturers, many different CNC control units are in use. Control units from different manufacturers use a variety of program formats and codes. Many CNC code words are identical for different controllers, but a great number vary from one to another. To produce an identical part on CNC machine tools with different controllers such as one by FANCU, OKUMA or DYNAPATH, would require pletely different CNC codes. Each manufacturer is constantly improving and updating its CNC controllers. These improvements often include additional code words plus changes in how the existing code works. A CAM system allows the CNC programmer to concentrate on the creation of an efficient machining process, rather than relearning changed code formats. A CNC programmer looks at the print of a part and then plans the sequence of machining operations necessary to make it (Figure O3). This plan includes everything, from the selection of possible CNC machine tools, to which tooling to use, to how the part is held while machining takes place. The CNC programmer has to have a thoroughunderstanding of all the capacities and limitations of the CNC machine tools that a program is to be made for. Machine specifications such as horsepower, maximum spindle speeds, workpiece weight and size limitations, and tool changer capacity are just some of the considerations that affect programming. Another area of major importance to the programmer is the knowledge of machining processes. An example would be the selection of the surface finish requirement specified in the part print. The sequence of machining processes is critical to obtain acceptable results. Cutting tool limitations have to be considered and this requires knowledge of cutting tool materials, tool types, and application remendations. A good programmer will spend a considerable amount of time in researching the rapidly growing volume of new and improved tools and tool materials. Often the tool that was on the cutting edge of technology just two years ago is now obsolete. Information on new tools can e from catalogs or tool manufacturers39。 由資金耗費項目上的考慮，就 CNC 機床刀具而言，為了明確新計劃是否必要或證明在短期內(nèi)實現(xiàn)資金回收，一個公司必須進行可行性分析。新的控制器的產(chǎn)生便使公司可通過改變程序改變了一個工件外形。用這種方式，自動換刀特性使這加工中心高效的加工多種部件，用新刀具代替舊刀具或預選刀具，使得現(xiàn)今的加工過程循環(huán)操作。作為一個鉆操作的機床刀具的點至點移動例子，典型的運動是快速經(jīng)過在鉆主軸下的工件，鉆空后，迅速的滑移的運動可能過每軸以連續(xù)且獨立的方式獲得。辛辛那提機床刀具公司把他們的一個 28 英寸的“ Hydro— Tel”軍用機床改裝為三軸自動機床，改變了它們的外部輪廓。 數(shù)控機床刀具早期的發(fā)展 今天在機器化大生產(chǎn)領域中千形百態(tài)，結構復雜的刀具，起源于一些主要的工業(yè)國，開始很簡陋。一些 CAD 和 CAM 程序，如果在相同的計算機上下載，可同時使用一些按鍵、圖紙和程序，使其能相互匹配。若不只一個 CNC 機床可以來加工這工件，制作代碼和比較在加工總時間可以表示一個機床是否比另一個機床該更有效， CAM/CAD 另一個確立刀具路徑的方法是借助計算機輔助繪圖。運行時，指定機床的代碼發(fā)生器相當于四個不同的鍵。首先，在 CAM 中編譯已加工孔的外部輪廓，再把外部輪廓當成粗基準來加工內(nèi)孔。對鉆床而言，一旦孔的位置坐標和深度被給出，一個孔就給出現(xiàn)在那點。點控公司（ POINT CPNTROLL COMPANY）的 SMARTCAM 系統(tǒng)使用接下來的手段：首先設計人員使用一個金屬零件模型去加工。對于光潔度的加工， 零件在加工中最小進給量被選定，接著切削速度直到轉速與機床的最佳轉速相等時才不變。這個加工過程的程序是吹毛求疵地獲得符合的結果。這些改進通常包括附加的代碼語句在已有代碼如何工作上的變化。在很多情況下，一個 CNC 機床完成了要建立幾臺相同傳統(tǒng)機床才能做的操作。零件的設計變化通過改變控制機床的程序而相對容易實現(xiàn)。它的切削刀具是標準的刀具如磨床的刀具、鉆子、鉆探工具或車刀，這些刀具依賴于所使用的機床型號。 CNC 控制器能被用來驅(qū)動和控制多種機床和機構。 指導教師評語： 簽名： 年 月 日 先進的加工工藝 隨著先進科技的硬件變得復雜化，把原料加工成為有用產(chǎn)品的理想的、新的加工手段得到了普遍應用。由于計算機能力和容量的巨大增長，機床的控制技術很頻繁地發(fā)生著變化。數(shù)控機床不會在一次加工完成后停下來計劃下一次的運動，它不會疲勞，它是不中斷的機床，機床只 有在它切削的時候才有生產(chǎn)性。一旦程序準 備好并加工零件，每個零件都將花與第一個一樣的時間。各個不同的廠家的控制單 元使用各個不相同的程序與代碼。這個設計包括以下每個因素 ，從可能使用的 CNC 機床的選擇，到機床的使用選擇，再到加工時的零件裝夾的選擇。通常在切削方面使用兩年前的技術的刀具現(xiàn)在就是落后的。 為加工中心使用的軟件是 ENGERSOLL CUTTING TOOL 公司的 ACTUAL CHIP THICKNESS。被使用的裝夾夾具是虎鉗，抓盤還是卡盤？這些考慮之后，計算機輸出就可開始了。當一條直線被編入程序， TOOLPATH 就會生動的顯示，其錯誤也可立即被糾正。由于用不同的顏色代表不同的刀具，所以觀察不同刀具的軌跡是很容易的。這個文件可提供最大的進給速度、轉速、加工時間等等。這圖形可表示零件的外形輪廓、孔等等。用正確的方法提升重的工作部件，或固定重的切削刀具。問題是怎么樣來克服來自常規(guī)的加工方法和手工制作的不足。 1956 年更可靠的曲線路徑控制系統(tǒng)開始使用。最早的這些點到點機床長循環(huán)的球形螺絲釘，這就意味著那些運動必須很緩慢，移動中遇到的沖擊不可避免，關于這個問題下章有更詳細的敘述。這個運輸裝置讓工件放 在托盤上送至所需的機床刀具下。這些現(xiàn)實是： 集成電路的發(fā)展，它減少了電路的尺寸，使得維護便利且有利于設計的標準化。 lasers, plasmaarc, flame cutting, and waterjets for cutting of steel plate。s maximum horsepower for roughing cuts. For a finishing cut, the smallest diameter of the part being machined is selected and then the cutting speed varied until the RPM is equal to the maximum RPM of the machine. This helps in maximizing machining efficiency. Knowing the horsepower requirement for a cut is critical if more than one tool is cutting at the same time. Software for a machining center application would be Ingersoll Tool Company39。 this meant that the motions would be sluggish, and sideways would inevitably suffer from backlash, but more will be said about this topic later in the chapter. The early NC machines were, in the main, based upon a modified milling machine with this concept of control being utilized on turning, punching, grinding and a whole host of other machine tools later. Towards the end of the 1950s,hydrostatic sideways were often incorporated for machine tools of highl y precision, which to sonic extent overcame the section problem associated with conventional sideway response, whiles averagingout sideway inaccuracy brought about a much increased preasion in the machine tool and improved their control characteristics allows concept of the machining center was the product of this early work, as it allowed the machine to manufactu