【正文】 milling cutters, drills, boring tools, or lathe tools depending on the type of machine used. Cutting speeds and feeds need to be correct as in any other machining operation. The greatest advantage in CNC machining es from the unerring and rapid positioning movements possible. A CNC machine does dot stop at the end of a cut to plan its next move。s Actual Chip Thickness, a program used to calculate the chip thickness in relation to feedpertooth for a milling cutter, especially during a shallow finishing cut. Ingersoll39。 that general purpose puters were reduced in size coupled to the fact that their cost of production had fallen considerably. The multipie benefits of cheaper electorics with greater reliability have result in the CNC fitted to the machine tools today, with the power and sophistication progtessing considerably in the last few years, allowing an almost artificial intelligence(AI) to the latest systems. Over the years, the machine tools builders have produced a large diversity in the range of applications of CNC and just some of those development will be reviewed in Volume Ⅲ 。本書的這個(gè)部分僅是一般介紹 而不能作為專業(yè)機(jī)床的設(shè)計(jì)手冊(cè)。 CNC 機(jī)床的最大優(yōu)勢(shì)來自無錯(cuò)的和快速的可能運(yùn)動(dòng)的控制。 CNC 機(jī)床不需要額外的時(shí)間和特別的預(yù)防就可生產(chǎn)高精度的嚴(yán)格公差的零件。 CAM 和 CNC CAM 系統(tǒng)改變了 CNC 程序員的工作，即從手工編制 CNC 代碼到 CNC 機(jī)床的輸出最大值。 CAM 系統(tǒng)允許 CNC 程序員在高效的加工過程的建立上濃縮、精選、而不重新學(xué)習(xí)已改變的代碼格式。機(jī)床極限能力必須考慮全面，這就需要刀具材料，刀具類型，和其推薦應(yīng)用的知識(shí)。這就幫助最大提高了機(jī)床效率。這包括的加工方式是 車或磨。如果其位置是錯(cuò)的，其撤消命令選擇這一記錄，并允許你給這個(gè)工序新的值。根據(jù)輸入切削的寬和深以及完成切削需切去的材料，計(jì)算機(jī)產(chǎn)生粗切削的加工程序。JOBPLAN 文件運(yùn)行時(shí)，表示刀具信息， GRAPHICS 文件表示刀具路徑和切削順序。大多數(shù)的機(jī)械繪圖使用電腦存儲(chǔ)了零件平面圖形及其注釋。 機(jī)床周圍應(yīng)該保持清潔，并且無導(dǎo)致絆倒或打滑的障礙物。這個(gè)領(lǐng)域中，最早的一些研究和發(fā)展完成于美國(guó)，并記載了 UK 關(guān)于數(shù)控發(fā)展方面的貢獻(xiàn)。在控制桌面位置，典型的機(jī)床是三軸連續(xù)曲線的機(jī)床刀具，它能產(chǎn)生一個(gè)所需要的形狀或曲線，可能的話，通過一個(gè)連續(xù)的滑移實(shí)現(xiàn)。分開的控制可由每軸完成，在早期的點(diǎn)到點(diǎn)機(jī)床中，選取路徑不很重要，但它必須避免在獲得多需要精度中所產(chǎn)生的沖擊。 在 19 世紀(jì) 60 年代中時(shí)，一個(gè) UK 公司， Molins 介紹他們獨(dú)特的“系統(tǒng) 24”意思是一天能加工 24 小時(shí)。微型技 術(shù)的發(fā)展，可成功的加工一批或一個(gè) 2 全件。這些想法及重要的決定將會(huì)成為考慮 CNC 系統(tǒng)經(jīng)濟(jì)性調(diào)整問題的主題。這些現(xiàn)實(shí)是： 集成電路的發(fā)展，它減少了電路的尺寸，使得維護(hù)便利且有利于設(shè)計(jì)的標(biāo)準(zhǔn)化。這個(gè)運(yùn)輸裝置讓工件放在托盤上送至所需的機(jī)床刀具下。最早的這些點(diǎn)到點(diǎn)機(jī)床長(zhǎng)循環(huán)的球行螺絲釘，這就意味著那些運(yùn)動(dòng)必須很緩慢，移動(dòng)中遇到的沖擊不可避免，關(guān)于這個(gè)問題下章有更詳細(xì)的敘述。 1956 年更可靠的曲線路徑控制系統(tǒng)開始使用。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。用正確的方法提升重的工作部件，或固定重的切削刀具。這圖形可表示零件的外形輪廓、孔等等。這個(gè)文件可提供最大的進(jìn)給速度、轉(zhuǎn)速、加工時(shí)間等等。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。當(dāng)一條直線被編入程序， TOOLPATH 就會(huì)生動(dòng)的顯示，其錯(cuò)誤也可立即被糾正。被使用的裝夾夾具是虎鉗，抓盤還是卡盤？這些考慮之后，計(jì)算機(jī)輸出就可開始了。 為加工中心使用的軟件是 ENGERSOLL CUTTING TOOL 公司的 ACTUAL CHIP THICKNESS。通常在切削方面使用兩年前的技術(shù)的刀具現(xiàn)在就是落后的。這個(gè)設(shè)計(jì)包括以下每個(gè)因素，從可能使用的 CNC 機(jī)床的選擇，到機(jī)床的使用選擇，再到加工時(shí)的零件裝夾的選擇。各個(gè)不同的廠家的控制單元使用各個(gè)不相同的程序與代碼。一旦程序準(zhǔn)備好并加工零件，每個(gè)零件都將花與第一個(gè)一樣的時(shí)間。 當(dāng)切削過程被適當(dāng)?shù)倪M(jìn)給量和切削速度控制時(shí)，時(shí)間的節(jié)約可以通過快速的進(jìn)給率來完成。在機(jī)床控制發(fā)展中的精彩部分是在每個(gè)先進(jìn)技術(shù)上的使用變得很容易了。這已經(jīng)成為近幾年機(jī)床加工的發(fā)展趨勢(shì)。s SmartCam system uses the following approach. First, the programmer makes a mental model of the part to be machined. This includes the kind of machining to be performedturning or milling. Then the part print is studied to develop a machining sequence, roughing and finishing cuts, drilling, tapping, and boring operations. What workholding device is to be used, a vise or fixture or clamps? After these considerations, puter input can be started. First es the creation of a JOBPLAN. This JOBPLAN consists of entries such as inch or metric units, machine type, part ID, type of workpiece material, setup notes, and a description of the required tools. This line of information describes the tool by number, type, and size and includes the appropriate cutting speed and feed rate. After all the selected tools are entered, the file is saved. The second programming step is the making of the part. This represents a graphic modeling of the projected machining operation. After selecting a tool from the prepared JOBPLAN, parameters for the cutting operation are entered. For a drill, once the coordinate location of the hole and the depth are given, a circle appears on that spot. If the location is incorrect, the UNDO mand erases this entry and allows you to give new values for this operation. When an end mill is being used, cutting movements (toolpath) are usually defined as lines and arcs. As a line is programmed, the toolpath is graphically displayed and errors can be corrected instantly. At any time during programming, the mand SHOWPATH will show the actual toolpath for each of the programmed tools. The tools will be displayed in the sequence in which they will be used during actual machining. If the sequence of a tool movement needs to be changed, a few keystrokes will to that. Sometimes in CAM the programming sequence is different from the actual machining order. An example would be the machining of a pocket in a part. With CAM, the finished pocket outline is programmed first, then this outline is used to define the roughing cuts to machine the pocket. The roughing cuts are puter generated from inputs such as depth and width of cut and how much material to leave for the finish cut. Different roughing patterns can be tried out to allow the programmer to select the most efllcient one for the actual machining cuts. Since each tool is represented by a different color, it is easy to observe the toolpath made by each one. A CAM system lets the programmer view the graphics model from varying angles, such as a top, front, side, or isometric view. A toolpath that looks correct from a top view, may show from a front view that the depth of the cutting tool is incorrect. Changes can easily be made and seen immediately. When the toolpath and the sequence of operations are satisfactory, machine ready code has to be made. This is as easy as specifying the CNC machine that is to be used to machine the part. The code generator for that specific CNC machine during processing accesses four different files. The JOBPLAN file for the tool information and the GRAPHICE file for the toolpath and cutting sequence. It also uses the MACHINE DEFINE file which defines the CNC code words for that specific machine. This file also supplies da