本科毕业设计(论文) 外文翻译
姓 名: 王文超
学 号： [1**********]0
专 业: 电气工程及其自动化
班 级: 电气071502
指导教师: 智泽英
职 称： 副教授
日 期: 2011年6月12日
电子信息工程学院
The basics of Computer Numerical Control
While the specific intention and application for CNC machines vary from machine type to
another, all forms of CNC have common benefits. Though the thrust of this presentation is to teach you CNC usage, it helps to understand why these sophisticated machines have become so popular. 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 a 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-overs. Since these machines are very easy to setup and run, and since programs can be easily loaded, they allow very short setup time. This is imperative with today’s Just-In-Time product requirements.
1. Motion control-the heart of CNC
The most basic function of any CNC machine is automatic, precise, and consistent motion. 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 manner. 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.
Accurate positioning is accomplished by the operator counting the number of revolutions made on the handwheel plus the graduations on the dial. The drive motor is rotated a corresponding amount, which in turn drives the ball screw, causing linear motion of the axis. A feedback device confirms that the proper amount of ball screw revolutions has occurred.
A CNC command executed within the control (commonly through a program) 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 causes drives the linear axis. A feedback device at the opposite end of the ball screw allows the control to confirm that the commanded number of rotations has taken place.
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 amount. (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 move popular of these two is the rectangular coordinate system, and we ’ll use it for all discussions made during this presentation.
One very common application for the rectangular coordinate system is graphing. Almost everyone has had to make or interpret a graph. Since the need to utilize graphs is so commonplace, and since it closely resembles what is required to cause axis motion on a CNC machine, let ’s review the basics of graphing.
As with any two dimensional graphs, this type of graph has two base lines. Each base line is used to represent something. What the base line represents is broken into increments. Also, each base line has limits. In our productivity example, the horizontal base line is being used to represent time. For this base line, the time increment is in months. Remember this base line has limits-it starts at January and end with December. The vertical base line is representing productivity. Productivity is broken into ten percent increments and starts at zero
percent productivity and ends with one hundred percent productivity.
The person making the graph would look up the company ’s productivity for January of last year and at the productivity position on the graph for January, a point is plotted. This would when be repeated for February, March, and each month of the year. Once all points are plotted, a line or curve can be drawn through each of the points to make it more clear as to how the company did last year.
Let ’s take what we now know about graphs and relate it to CNC axis motion. Instead of plotting theoretical points to represent conceptual ideas, the CNC programmer is going to be plotting physical end points for axis motions. Each linear axis of the machine tool can be thought of as like a base line of the graph. Like graph base lines, axes are broken into increments. But instead of being broken into increments of conceptual ideas like time and productivity, each linear axis of a CNC machine’s rectangular coordinate system is broken into increments of measurement. In the inch mode, the smallest increment is usually 0.0001 inch (in). In the metric mode, the smallest increment is 0.001 millimeter (mm). (By the way, for rotary axes the increment is 0.001).
Just like the graph, each axis within the CNC machine’s coordinate system must start somewhere. With the graph, the horizontal base line started at January and the vertical base line starter at zero percent productivity. This place where the vertical and horizontal base lines come together is called the origin point of the graph. For CNC purposes, this origin point is commonly caller the program zero point (also called work zero, part zero, and program origin).
For this example, the two axes we happen to be showing are labeler as X and Y but keep in mine that program zero can be applied to any axis. Though the names of each axis will change from one CNC machine type to another (other common names include Z, A, B, C, U, V, and W), this example should work nicely to show you how axis motion can be commanded.
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, is 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 commander destination point. This lets the programmer command axis motion in a very logical manner.
With the examples given so far, all points happened to be up and to the right of the program zero point. This area up and to the right of the program zero point is called a quadrant (in this case, quadrant number
one). It is not uncommon on CNC machines that end points needed within the program fall in other quadrants. When this happens, at least one of the coordinates must be specified as minus.
2. Understanding absolute versus incremental motion
All discussions to this point assume that the absolute mode of programming is used. 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.
3. 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 another. 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 (orG50) 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. 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. More on how program zero can be assigned will be
presented during key concept number four.
4. Other points about axis motion
To this point, our primary concern has been to show you how to determine the end point of each motion command. As you have seen, doing this requires an understanding of the rectangular coordinate system. However, there are other concerns about how a motion will take place. Fore example, the type of motion (rapid, straight line, circular, etc.), and motion rate (feedrate), will also be of concern to the programmer. We ’ll discuss these other considerations during key concept number three.
5. Telling the machine what to do-the CNC program
Almost all current CNC controls use a word address format for programming. (The only exceptions to this are certain conversational control.) By word address format, we mean that the CNC program is made up of sentence-like commands. Each command is made up of CNC words. Each CNC word has a letter address and a numerical value. The letter address (X, Y, Z, etc.) tells the control the kind of word and the numerical value tells the control the value of the word. Used like words and sentences in the English language, words in a CNC command tell the CNC machine what we wish to do at the present time.
One very good analogy to what happens in a CNC program is found in any set of step by step instructions. Say for example, you have some visitors coming in from out of town to visit your company. You need to write down instructions to get from the local airport to your company. To do so, you must first be able to visualize the path from the airport to your company. You will then, in sequential order, write down one instruction at a time. The person following your instructions will perform the first step and then go on to the next until he or she reaches your company.
In similar manner, a manual CNC programmer must be able to visualize the machining operations that are to be performed during the execution of the program. Then, in step by step order, the programmer will give a set of commands that makes the machine behave accordingly.
Though slight off the subject at hand, we wish to make a strong point about visualization. Just as the person developing travel directions MUST be able to visualize the path taken, so MUST the CNC programmer be able to visualize the movements the CNC machine will be making BEFORE a program can be successfully developed. Without this visualization ability, the programmer will not be able to develop the movements in the program correctly. This is one reason why machinists make the best CNC users. An experienced machinist should be able to easily visualize any machining operation taking place.
Just as each concise travel instruction will be made up of one sentence, so will each instruction given within a CNC program be made up of one command. Just as the travel instruction sentence is made up of words (in
English), so is the CNC command made up of CNC words (in CNC language).
The person following your set of travel instructions will execute them explicitly. If you make a mistake with your set of instructions, the person will get lost on the way to your company. In similar fashion, the CNC machine will execute a CNC program explicitly. If there is a mistake in the program, the CNC machine will not behave correctly.
While the words and commands in this program probably do not make much sense to you (yet), remember that we are stressing the sequential order by which the CNC program will be executed. The control will first read, interpret and execute the very first command in the program. Only then will it go on to the next command. Read, interpret, execute. Then go to the next command. The control will continue to execute the program in sequential order for the balance of the program. Again, notice the similarity to giving any set of step by step instructions.
6. Other notes about program makeup
As stated programs are made up of commands and commands re made up of word. Each word has a letter address and a numerical value. The letter address tells the control the word type. CNC control manufacturers do vary with regard to how they determine word names (letter addresses) and their meanings. The beginning CNC programmer must reference the control manufacturer ’s programming manual to determine the word names and meanings. Here is a brief list of some of the word types and their common letter address specifications.
7. M-Miscellaneous function (See below)
As you can see, many of the letter addresses are chosen in a rather logical manner (T for tool, S for spindle, F for federate, etc.). A few require memorizing.
There are two letter addresses (G and M) which allow special functions to be designated. The preparatory function (G) specified is commonly used to set modes. We already introduced absolute mode, specified by G90 and incremental mode, specified by G91. There are but two of the preparatory functions used. You must reference your control manufacturer’s manual to find the list of preparatory functions, miscellaneous functions for your particular machine.
Like preparatory functions, miscellaneous functions (M words) allow a variety of special functions. Miscellaneous functions are typically used as programmable switches (like spindle on/off, coolant on/off, and so on). They are also used to allow programming of many other programmable functions of the CNC machine tool.
To a beginner, all of this may seem like CNC programming requires a great deal of memorization. But rest assured that there are only about 30-40 different words used with CNC programming. If you can think of learning CNC manual programming as like learning a foreign language that has only 40 words, it shouldn’t seem too difficult.
计算机数字控制基础
CNC 机器的特别目的和应用，他们的类型是不断地从这变化到另外的。但实际上，所有形式的 CNC 都是有共同的特点，有共同的用处。 从插口的说明指导书可以教你 CNC 的使用方法, 它可以帮助你了解为什么这些复杂的机器现在已经变得这么流行。下面列举出来的是 CNC 设备所提供出来的一些重要的用处。
第一，从所有形式的 CNC 工作母机得到的第一种好处就是经过改造后可实现全自动化。从而生产工件的操作员将会被大大减少或者干脆不用。许多 CNC 机器能不需要操作员就可以自动地在它的机器周期里安全运转，从而这也就解放了一些操作员，使他们有时间可以去做别的事情。这样给CNC 的使用者带来几种好处：既可以降低了操作员的疲累度，又可以减少由于人工所引起的错误，每个工件的加工时间就可以预期和统一。因为机器是利用程序来控制，所以CNC 的使用者的技术要求水平相对传统的机械师使用机械工具来生产工件的要求也有所下降（相关的机器练习）。
第二，另外的好处是CNC 技术基础是统一的，对工件的加工精度也比较高。 现在的 CNC 机器都有几乎难以置信的精度和重复性规格。这也就意味着，一旦一个程序经过验证，就会有两个或者十个甚至上千个同样的工件可以轻松得按高精度统一来生产。
第三，CNC 工作母机得到的第三种好处是设计具有弹性，有机动性。因为这些机器是按照程序来运行控制的，改造一个工件几乎就像装载一个不同的程序那么简单。一旦有一段程序被验证成功并且用来指导生产工件，下次还可以调出来使用，对工件进行加工。这样就又有另外一个好处：快速变化。因为这些机器的装配和运转比较容易，程序装载容易，所需要的时间短。这些可以满足了当今产品的即时生产要求。
1、运动控制-CNC 的核心
大部分的 CNC 机器的最基本功能是自动化，高精确度和一致协调的运动。并非像应用完整的传统机器设备来产生运动，CNC 机器的运动使用了一个全新的
方式。即所有的CNC 机器设备具有两个或两个以上的运动方向，也就是通常所说的轴向运动。这些轴可以精确地，自动地沿着它们的长度运动。最常见的两种轴是：一种是线性的（沿一条直线的路径驱动），另一种是旋转式的（沿着一条圆形的路径驱动）。
CNC 机器设备是按照程序的要求来运动，并非由曲柄和手轮需要在传统的工作母机上引起运动。一般来说, 运动类型 (快速，直线，圆形) 、轴的移动方向、轴运动的数量和速率几乎都是可以通过 CNC 工作母机编程来设计得到。
正确配置的完成也需要操作员计算手轮上面的刻度旋转的数值，轮流驱动螺旋桨的引起沿着轴直线运动的旋转马达的相应数量，还有一个反馈装置用以确定螺旋桨的适当数量。
一条CNC 控制的指令（一般是在一段程序内）告诉马达在一个时段内驱动一个精确的数量。马达轮流驱动螺旋桨，然后螺旋桨驱动线性的轴承。在相反端的螺旋桨的反馈设备允许控制以确定所要求的数量的旋转运动的发生。
虽然类推的方法比较粗糙，但是同样的基本线性运动可以在普通的虎头钳曲柄找到。当你旋转虎头钳曲柄时候，你可以引领螺丝钉，驱动虎头钳活动的钳叉。通过比较，在一个 CNC 工作母机上的一个线性的非常地精确，许多的轴旋转来驱动，精确地控制轴上面的线性运动。
轴的运动如何，它们可以被命令和了解并接受同等的系统。它会让 CNC 使用者尝试去编程实现告诉引起轴如何去运动，每个轴驾驶马达如何替换，替换多少次。以达到要命令一个给定的线运动总量. (这会像必须理解柄的旋转在一个桌子虎头钳，将会导致可动的钳叉完全地精确的移动一寸!) 相反的, 所有的 CNC 控制利用一些形式的同等的系统在一个比较简单和更多很多合乎逻辑方法命令让轴运动。被 CNC 机器用的二个最流行的同等系统是矩形的同等系统和两极的同等系统。显然, 到目前为止，这两种同等系统比较流行的是矩形的。我们将会使用它作为在这发表期间做的所有的讨论。
一个的普遍的通常的应用矩形的同等系统是曲线图。几乎每个人必须制造或者解释一个曲线图。自从以后需要利用曲线图如此平凡, 而且自从它之后，更加接近一部 CNC 机器上的轴运动，下面让我们复习以下曲线图的基本。
关于任何的二个空间的曲线图, 这类型的曲线图有二条基线. 每个基线用
来表现某件事或者某个量。每个基线代表的是一个突然的增量。同时，每个线都是有个极限的，在我们的生产例子中, 水平的基线是用来表示时间。 对于这一条基线, 所有的增量都是以月来算。务必记得这一条基线是有极限，它以一月份开始，以十二月份做为结束。垂直的基线表示生产总量，以百分之十作为增量单位。从百分之零开始，以百分之百作为生产总量的结束。
制造曲线图的人会对于去年一月份公司的生产总量调查清楚，在生产总量所表示的曲线图上对应于一点, 这点可能会在二月，三月甚至在一年中的每个月中重复出现, 一经所有的点被标注后，一条由这些点组成的直线或者曲线就能通过每个点表示关于公司如何去年生产如何，使它变成更一目了然。
让我们拿我们现在知道曲线图而且使它和 CNC 轴上的运动产生关联。理论上的点只能表现概念上的意思, CNC 程序师要为轴运动设计实际运动的结束点。
工作母机的每个线轴能被设想到为同类曲线图的一条基线。 相似的曲线图以线作基础, 轴可以加入增量。 但是而非加入的增量与之前提到的增量时间和生产总量不同。一个 CNC 机器的矩形同等的系统的每个线轴所测量到的增量，在寸模态中, 最小的增量通常是 0.0001 寸。在公制的模态中, 最小的增量是 0.001 毫米。(顺便一提, 旋转的轴增量是 0.001)。
正如曲线图, CNC 机器的里面的每个轴同等的系统一定从某处开始。同曲线图, 在零的百分比生产力的在一月和垂直的基线起动器被开始的水平基线.
这一个地方，垂直的和水平的基线交点被称为曲线图的起源点。对于 CNC 的目的而言， 这起源点普遍被称为零点 (也叫做工作零，部份零和源点) 。
对于这一个例子, 二个轴我们可以分别贴标签为 X轴 和 Y轴 ，但是在我们的意念中零点适用于任何的轴。虽然每个轴的名字将会从一个 CNC 机器类型变成另外的 (其他的通常名字包括 Z ， A ， B ， C ， U ， V 和 W等等) ，但前提条件是这一个例子应该很好地工作来表示轴运动能如何被命令。
程序的零点建立涉及到了在CNC 中的运动指令，这让程序师叙述来自一个通常的位置的运动。如果零点被选择好, 通常程序的的匹配点就会直接得到。
因为有了这技术, 如果程序想要把工具送到一个一寸的地方，在零点的右边，X1.0就被确定了。如果程序想要把工具送到零点的上面一寸的地方，Y1.0就被确定了。这样控制点就会自动地定义旋转多少次轴去驱动电机和旋转轴来使
轴到达要求的目的地。这可以让程序师以非常合乎逻辑的样子命令轴运动。
在到现在为止被举出的例子中, 所有的点碰巧是在零点的上面或者右方。在这上面或者右边的空间就叫做一个象限（在这种情况下，第一象限）很难见到CNC 机器的终点需要在别的象限的程序中。当这发生的时候, ，至少有一个坐标被表示为负。
2. 了解绝对的逐渐增量的运动
对这点的所有讨论都是假设在绝对摸态的使用状态。最通常的 CNC 字过去一直指定绝对的模态是 G90 。 在绝对的模态中，所有运动的的结束点从程序的零点详细说明。对于初学者, 这通常是为运动指令叙述结束点的最好和最容易方法。然而，为轴运动叙述结束点还有另一个方法。
在逐渐增加的模态 (普遍被 G91 指定) 中，运动的结束点指出，从工具的现在位置被指定, 而表示不是零点。因为有指挥运动的这一个方法, 程序师必须总是问 "我应该移动工具多远? ” 当有时候逐渐增加的模态可能是非常有帮助的，一般来说，这应是叙述运动和初学者的更讨厌和更困难的方法，应该专注于使用绝对的模态。
当编写运动指令的时候，要小心。初学者应逐渐增加地去考虑的运动的趋向。如果是在绝对的模态 (如初学者) 中的工作，程序师总是应该考虑 "到什么位置工具应该被移动吗? ” 这一个位置应该和零点相关，而不是与工具现在的位置相关。
除了使任何的指令决定现在的位置是非常容易的之外, 在绝对的模态中工作的另一种好处是可以在运动指令期间处理所犯的错误。在绝对的模态中，如果一个在程序的指令中运行错误，那么只有一个运动是不正确的。从另外一个方面来说，如果一个错误在逐渐增加的运动期间发生，来自错误的点的所有的运动也将会是不正确的。
3. 分配程序零点
务必清醒地意识到， CNC 控制必须指出零点的位置，可以通过一种或者多种的方法。
如何处理，引人注目的改变CNC 机器和控制另外的机器，一个方法是分配程序的零点进入程序中。通过这种方法，程序员会告诉控制器从零点到机器开始的地方
有多远。这些一般在G92 (或者G50) 指令在程序的开头或者在每个工具的开头完成。
另外，更新和更好的方法来安排程序零点是通过一些偏移量的形式来安排。一般情况，机器控制中心呼叫偏移量，习惯以程序零点固定装置来弥补。旋转中心的制造者一般呼叫偏移程序零点对于每个工具的几何偏移。更多关于程序零点用以安排的零点将会在第四点那里的概念有所呈现。
4. 关于轴运动的其他点
对这点, 我们的主要关心是该如何决定每个运动指令的结束点。你应该已经知道，做这些需要明白了解矩形同等的系统。然而，有其他的因数关系到运动怎么样发生。例如，运动的类型（迅速的, 直线, 圆形的, 及其他.) ，运动的速率，还有程序本身。我们将会在第三点的概念那里讨论这些其他的考虑。
5. 告诉机器该如何运行CNC 程序
几乎所有现在的 CNC 控制使用一个字格式作为编程。(唯一的例外对这是特定的会话控制。) 由字格式, 我们意指 CNC 的程序像句子一样的指令组成. 每个指令由 CNC 字组成.
每个 CNC 字有一个字母地址和数字的值。字母地址 (X ，Y ，Z, 及其他.) 告诉控制字和数字的值类型和告诉控制字的数值。 就像运用的英语中的词和句子一样，一个 CNC 指令的字告诉 CNC 机器我们想要目前做的目的。
一个很好的例子，就像一个 CNC 程序中的在一步一步地指导。举个例子，你有一些采访者将来到这个城镇来参观你的公司。你需要写下从本地机场到你公司的详细路线说明。为了做好，你必须首先可以指引从机场到你公司的路径。然后，接下来，写下每次的说明。
那些人可以根据你的说明将可以完成第一步然后下一步，直到他或者她到达你的公司。
相似的样子, 一个 CNC 程序师一定能够看得见机制操作是在程序的执行期间被运行. 然后, 在一步一步地次序中, 程序师将会提供一系列指令适当地使机器的行为表现为连续。
正如发展旅行的人一定能够使拿的路径看得见，因此，必须使 CNC 程序师能够在一个程序是否成功地发展之前， CNC 机器将会产生的运动看得见。没有这
一种使看得见的能力, 程序师将不能够正确地在程序中命令轴运动。这是为什么机械师制造最好的 CNC 使用者的一个理由。一个富有经验的机械师应该能够容易地使任何的机制操作发生。
正如每个简洁的旅行指引，将会由一个句子组成。每个指引也会在一个 CNC 程序里面由一个指令组成。正如旅行指引的句子由字 (用英语) 组成, 也是被由 CNC 字组成的 CNC 指令 (以 CNC 语言) 。
跟随你的旅行指引的人将会明确旅游观光路线。如果你的指引路线出现错误, 被指引的人将会在前往你的公司的途中迷路。相似的例子, CNC 机器将会明确地运行一个 CNC 程序，如果在程序中有一个错误, ，CNC 机器将不能正确地执行任务。
当字和指令在这一个程序中或许没有让你引起注意 (仍然) 的时候, 要记得我们正在强调在 CNC 程序将会依据的指令的次序继续运行。控制系统将会首先写入，编译和运行程序中的第一指令，然后才执行下一步。控制系统就是不断地写入，编译，运行重复这些动作。然后跳到下一条指令。控制会继续在程序中平衡地继续的运行。同样，要注意给出的一步一步的指令。
6，关于程序的说明
就像程序是由指令组成一样，指令也是由一大串字来组成。每个字有一个字住址和数字值。字住址告诉控制字类型， CNC 控制器的制造者决定字名称 (字住址) 和他们的含义。CNC 初学编程者必须叁考控制制造者程序手册所定义的字名字和意义。这里是一本关于一些字类型的简短目录和他们的通常字住址。
7. M-各种功能 (在下面见到)
正如你所见, 许多字住址以相当合乎逻辑的形式来选择 (T 为工具， S 为纱锭， F 为同盟的, 及其他.). 一些需要记住.
有两种字地址(G 和 M).被允许指定特别的功能。(G) 普遍用来设定模态，我们已经介绍了被 G90 指定的绝对模态和被 G91 指定的逐渐增加的模态。有且只有两个预备的功能可用。你必须叁考你的控制制造者的手册，查找预备功能的目录, 还有你的机器的各种特别功能。
相似的预备功能, 各种的功能 (M 字) 允许多种特别的功能。各种的典型功能被来当设计的开关 (相似的纱锭 ON/OFF ，冷冻剂 ON/OFF, 等等). 他们也
用做CNC 机器工具的允许的许多其他可设计功能的编程。
对一位初学者, 好象CNC 的编程要记住很多东西。但实际上在CNC 编程中真正所用到的也只有大概30-40个不同的字。如果你把CNC 的编程看成像学习外语一样，它也就是40个字而已，那么学习起来不应该有困难。
本科毕业设计(论文) 外文翻译
姓 名: 王文超
学 号： [1**********]0
专 业: 电气工程及其自动化
班 级: 电气071502
指导教师: 智泽英
职 称： 副教授
日 期: 2011年6月12日
电子信息工程学院
The basics of Computer Numerical Control
While the specific intention and application for CNC machines vary from machine type to
another, all forms of CNC have common benefits. Though the thrust of this presentation is to teach you CNC usage, it helps to understand why these sophisticated machines have become so popular. 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 a 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-overs. Since these machines are very easy to setup and run, and since programs can be easily loaded, they allow very short setup time. This is imperative with today’s Just-In-Time product requirements.
1. Motion control-the heart of CNC
The most basic function of any CNC machine is automatic, precise, and consistent motion. 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 manner. 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.
Accurate positioning is accomplished by the operator counting the number of revolutions made on the handwheel plus the graduations on the dial. The drive motor is rotated a corresponding amount, which in turn drives the ball screw, causing linear motion of the axis. A feedback device confirms that the proper amount of ball screw revolutions has occurred.
A CNC command executed within the control (commonly through a program) 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 causes drives the linear axis. A feedback device at the opposite end of the ball screw allows the control to confirm that the commanded number of rotations has taken place.
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 amount. (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 move popular of these two is the rectangular coordinate system, and we ’ll use it for all discussions made during this presentation.
One very common application for the rectangular coordinate system is graphing. Almost everyone has had to make or interpret a graph. Since the need to utilize graphs is so commonplace, and since it closely resembles what is required to cause axis motion on a CNC machine, let ’s review the basics of graphing.
As with any two dimensional graphs, this type of graph has two base lines. Each base line is used to represent something. What the base line represents is broken into increments. Also, each base line has limits. In our productivity example, the horizontal base line is being used to represent time. For this base line, the time increment is in months. Remember this base line has limits-it starts at January and end with December. The vertical base line is representing productivity. Productivity is broken into ten percent increments and starts at zero
percent productivity and ends with one hundred percent productivity.
The person making the graph would look up the company ’s productivity for January of last year and at the productivity position on the graph for January, a point is plotted. This would when be repeated for February, March, and each month of the year. Once all points are plotted, a line or curve can be drawn through each of the points to make it more clear as to how the company did last year.
Let ’s take what we now know about graphs and relate it to CNC axis motion. Instead of plotting theoretical points to represent conceptual ideas, the CNC programmer is going to be plotting physical end points for axis motions. Each linear axis of the machine tool can be thought of as like a base line of the graph. Like graph base lines, axes are broken into increments. But instead of being broken into increments of conceptual ideas like time and productivity, each linear axis of a CNC machine’s rectangular coordinate system is broken into increments of measurement. In the inch mode, the smallest increment is usually 0.0001 inch (in). In the metric mode, the smallest increment is 0.001 millimeter (mm). (By the way, for rotary axes the increment is 0.001).
Just like the graph, each axis within the CNC machine’s coordinate system must start somewhere. With the graph, the horizontal base line started at January and the vertical base line starter at zero percent productivity. This place where the vertical and horizontal base lines come together is called the origin point of the graph. For CNC purposes, this origin point is commonly caller the program zero point (also called work zero, part zero, and program origin).
For this example, the two axes we happen to be showing are labeler as X and Y but keep in mine that program zero can be applied to any axis. Though the names of each axis will change from one CNC machine type to another (other common names include Z, A, B, C, U, V, and W), this example should work nicely to show you how axis motion can be commanded.
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, is 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 commander destination point. This lets the programmer command axis motion in a very logical manner.
With the examples given so far, all points happened to be up and to the right of the program zero point. This area up and to the right of the program zero point is called a quadrant (in this case, quadrant number
one). It is not uncommon on CNC machines that end points needed within the program fall in other quadrants. When this happens, at least one of the coordinates must be specified as minus.
2. Understanding absolute versus incremental motion
All discussions to this point assume that the absolute mode of programming is used. 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.
3. 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 another. 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 (orG50) 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. 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. More on how program zero can be assigned will be
presented during key concept number four.
4. Other points about axis motion
To this point, our primary concern has been to show you how to determine the end point of each motion command. As you have seen, doing this requires an understanding of the rectangular coordinate system. However, there are other concerns about how a motion will take place. Fore example, the type of motion (rapid, straight line, circular, etc.), and motion rate (feedrate), will also be of concern to the programmer. We ’ll discuss these other considerations during key concept number three.
5. Telling the machine what to do-the CNC program
Almost all current CNC controls use a word address format for programming. (The only exceptions to this are certain conversational control.) By word address format, we mean that the CNC program is made up of sentence-like commands. Each command is made up of CNC words. Each CNC word has a letter address and a numerical value. The letter address (X, Y, Z, etc.) tells the control the kind of word and the numerical value tells the control the value of the word. Used like words and sentences in the English language, words in a CNC command tell the CNC machine what we wish to do at the present time.
One very good analogy to what happens in a CNC program is found in any set of step by step instructions. Say for example, you have some visitors coming in from out of town to visit your company. You need to write down instructions to get from the local airport to your company. To do so, you must first be able to visualize the path from the airport to your company. You will then, in sequential order, write down one instruction at a time. The person following your instructions will perform the first step and then go on to the next until he or she reaches your company.
In similar manner, a manual CNC programmer must be able to visualize the machining operations that are to be performed during the execution of the program. Then, in step by step order, the programmer will give a set of commands that makes the machine behave accordingly.
Though slight off the subject at hand, we wish to make a strong point about visualization. Just as the person developing travel directions MUST be able to visualize the path taken, so MUST the CNC programmer be able to visualize the movements the CNC machine will be making BEFORE a program can be successfully developed. Without this visualization ability, the programmer will not be able to develop the movements in the program correctly. This is one reason why machinists make the best CNC users. An experienced machinist should be able to easily visualize any machining operation taking place.
Just as each concise travel instruction will be made up of one sentence, so will each instruction given within a CNC program be made up of one command. Just as the travel instruction sentence is made up of words (in
English), so is the CNC command made up of CNC words (in CNC language).
The person following your set of travel instructions will execute them explicitly. If you make a mistake with your set of instructions, the person will get lost on the way to your company. In similar fashion, the CNC machine will execute a CNC program explicitly. If there is a mistake in the program, the CNC machine will not behave correctly.
While the words and commands in this program probably do not make much sense to you (yet), remember that we are stressing the sequential order by which the CNC program will be executed. The control will first read, interpret and execute the very first command in the program. Only then will it go on to the next command. Read, interpret, execute. Then go to the next command. The control will continue to execute the program in sequential order for the balance of the program. Again, notice the similarity to giving any set of step by step instructions.
6. Other notes about program makeup
As stated programs are made up of commands and commands re made up of word. Each word has a letter address and a numerical value. The letter address tells the control the word type. CNC control manufacturers do vary with regard to how they determine word names (letter addresses) and their meanings. The beginning CNC programmer must reference the control manufacturer ’s programming manual to determine the word names and meanings. Here is a brief list of some of the word types and their common letter address specifications.
7. M-Miscellaneous function (See below)
As you can see, many of the letter addresses are chosen in a rather logical manner (T for tool, S for spindle, F for federate, etc.). A few require memorizing.
There are two letter addresses (G and M) which allow special functions to be designated. The preparatory function (G) specified is commonly used to set modes. We already introduced absolute mode, specified by G90 and incremental mode, specified by G91. There are but two of the preparatory functions used. You must reference your control manufacturer’s manual to find the list of preparatory functions, miscellaneous functions for your particular machine.
Like preparatory functions, miscellaneous functions (M words) allow a variety of special functions. Miscellaneous functions are typically used as programmable switches (like spindle on/off, coolant on/off, and so on). They are also used to allow programming of many other programmable functions of the CNC machine tool.
To a beginner, all of this may seem like CNC programming requires a great deal of memorization. But rest assured that there are only about 30-40 different words used with CNC programming. If you can think of learning CNC manual programming as like learning a foreign language that has only 40 words, it shouldn’t seem too difficult.
计算机数字控制基础
CNC 机器的特别目的和应用，他们的类型是不断地从这变化到另外的。但实际上，所有形式的 CNC 都是有共同的特点，有共同的用处。 从插口的说明指导书可以教你 CNC 的使用方法, 它可以帮助你了解为什么这些复杂的机器现在已经变得这么流行。下面列举出来的是 CNC 设备所提供出来的一些重要的用处。
第一，从所有形式的 CNC 工作母机得到的第一种好处就是经过改造后可实现全自动化。从而生产工件的操作员将会被大大减少或者干脆不用。许多 CNC 机器能不需要操作员就可以自动地在它的机器周期里安全运转，从而这也就解放了一些操作员，使他们有时间可以去做别的事情。这样给CNC 的使用者带来几种好处：既可以降低了操作员的疲累度，又可以减少由于人工所引起的错误，每个工件的加工时间就可以预期和统一。因为机器是利用程序来控制，所以CNC 的使用者的技术要求水平相对传统的机械师使用机械工具来生产工件的要求也有所下降（相关的机器练习）。
第二，另外的好处是CNC 技术基础是统一的，对工件的加工精度也比较高。 现在的 CNC 机器都有几乎难以置信的精度和重复性规格。这也就意味着，一旦一个程序经过验证，就会有两个或者十个甚至上千个同样的工件可以轻松得按高精度统一来生产。
第三，CNC 工作母机得到的第三种好处是设计具有弹性，有机动性。因为这些机器是按照程序来运行控制的，改造一个工件几乎就像装载一个不同的程序那么简单。一旦有一段程序被验证成功并且用来指导生产工件，下次还可以调出来使用，对工件进行加工。这样就又有另外一个好处：快速变化。因为这些机器的装配和运转比较容易，程序装载容易，所需要的时间短。这些可以满足了当今产品的即时生产要求。
1、运动控制-CNC 的核心
大部分的 CNC 机器的最基本功能是自动化，高精确度和一致协调的运动。并非像应用完整的传统机器设备来产生运动，CNC 机器的运动使用了一个全新的
方式。即所有的CNC 机器设备具有两个或两个以上的运动方向，也就是通常所说的轴向运动。这些轴可以精确地，自动地沿着它们的长度运动。最常见的两种轴是：一种是线性的（沿一条直线的路径驱动），另一种是旋转式的（沿着一条圆形的路径驱动）。
CNC 机器设备是按照程序的要求来运动，并非由曲柄和手轮需要在传统的工作母机上引起运动。一般来说, 运动类型 (快速，直线，圆形) 、轴的移动方向、轴运动的数量和速率几乎都是可以通过 CNC 工作母机编程来设计得到。
正确配置的完成也需要操作员计算手轮上面的刻度旋转的数值，轮流驱动螺旋桨的引起沿着轴直线运动的旋转马达的相应数量，还有一个反馈装置用以确定螺旋桨的适当数量。
一条CNC 控制的指令（一般是在一段程序内）告诉马达在一个时段内驱动一个精确的数量。马达轮流驱动螺旋桨，然后螺旋桨驱动线性的轴承。在相反端的螺旋桨的反馈设备允许控制以确定所要求的数量的旋转运动的发生。
虽然类推的方法比较粗糙，但是同样的基本线性运动可以在普通的虎头钳曲柄找到。当你旋转虎头钳曲柄时候，你可以引领螺丝钉，驱动虎头钳活动的钳叉。通过比较，在一个 CNC 工作母机上的一个线性的非常地精确，许多的轴旋转来驱动，精确地控制轴上面的线性运动。
轴的运动如何，它们可以被命令和了解并接受同等的系统。它会让 CNC 使用者尝试去编程实现告诉引起轴如何去运动，每个轴驾驶马达如何替换，替换多少次。以达到要命令一个给定的线运动总量. (这会像必须理解柄的旋转在一个桌子虎头钳，将会导致可动的钳叉完全地精确的移动一寸!) 相反的, 所有的 CNC 控制利用一些形式的同等的系统在一个比较简单和更多很多合乎逻辑方法命令让轴运动。被 CNC 机器用的二个最流行的同等系统是矩形的同等系统和两极的同等系统。显然, 到目前为止，这两种同等系统比较流行的是矩形的。我们将会使用它作为在这发表期间做的所有的讨论。
一个的普遍的通常的应用矩形的同等系统是曲线图。几乎每个人必须制造或者解释一个曲线图。自从以后需要利用曲线图如此平凡, 而且自从它之后，更加接近一部 CNC 机器上的轴运动，下面让我们复习以下曲线图的基本。
关于任何的二个空间的曲线图, 这类型的曲线图有二条基线. 每个基线用
来表现某件事或者某个量。每个基线代表的是一个突然的增量。同时，每个线都是有个极限的，在我们的生产例子中, 水平的基线是用来表示时间。 对于这一条基线, 所有的增量都是以月来算。务必记得这一条基线是有极限，它以一月份开始，以十二月份做为结束。垂直的基线表示生产总量，以百分之十作为增量单位。从百分之零开始，以百分之百作为生产总量的结束。
制造曲线图的人会对于去年一月份公司的生产总量调查清楚，在生产总量所表示的曲线图上对应于一点, 这点可能会在二月，三月甚至在一年中的每个月中重复出现, 一经所有的点被标注后，一条由这些点组成的直线或者曲线就能通过每个点表示关于公司如何去年生产如何，使它变成更一目了然。
让我们拿我们现在知道曲线图而且使它和 CNC 轴上的运动产生关联。理论上的点只能表现概念上的意思, CNC 程序师要为轴运动设计实际运动的结束点。
工作母机的每个线轴能被设想到为同类曲线图的一条基线。 相似的曲线图以线作基础, 轴可以加入增量。 但是而非加入的增量与之前提到的增量时间和生产总量不同。一个 CNC 机器的矩形同等的系统的每个线轴所测量到的增量，在寸模态中, 最小的增量通常是 0.0001 寸。在公制的模态中, 最小的增量是 0.001 毫米。(顺便一提, 旋转的轴增量是 0.001)。
正如曲线图, CNC 机器的里面的每个轴同等的系统一定从某处开始。同曲线图, 在零的百分比生产力的在一月和垂直的基线起动器被开始的水平基线.
这一个地方，垂直的和水平的基线交点被称为曲线图的起源点。对于 CNC 的目的而言， 这起源点普遍被称为零点 (也叫做工作零，部份零和源点) 。
对于这一个例子, 二个轴我们可以分别贴标签为 X轴 和 Y轴 ，但是在我们的意念中零点适用于任何的轴。虽然每个轴的名字将会从一个 CNC 机器类型变成另外的 (其他的通常名字包括 Z ， A ， B ， C ， U ， V 和 W等等) ，但前提条件是这一个例子应该很好地工作来表示轴运动能如何被命令。
程序的零点建立涉及到了在CNC 中的运动指令，这让程序师叙述来自一个通常的位置的运动。如果零点被选择好, 通常程序的的匹配点就会直接得到。
因为有了这技术, 如果程序想要把工具送到一个一寸的地方，在零点的右边，X1.0就被确定了。如果程序想要把工具送到零点的上面一寸的地方，Y1.0就被确定了。这样控制点就会自动地定义旋转多少次轴去驱动电机和旋转轴来使
轴到达要求的目的地。这可以让程序师以非常合乎逻辑的样子命令轴运动。
在到现在为止被举出的例子中, 所有的点碰巧是在零点的上面或者右方。在这上面或者右边的空间就叫做一个象限（在这种情况下，第一象限）很难见到CNC 机器的终点需要在别的象限的程序中。当这发生的时候, ，至少有一个坐标被表示为负。
2. 了解绝对的逐渐增量的运动
对这点的所有讨论都是假设在绝对摸态的使用状态。最通常的 CNC 字过去一直指定绝对的模态是 G90 。 在绝对的模态中，所有运动的的结束点从程序的零点详细说明。对于初学者, 这通常是为运动指令叙述结束点的最好和最容易方法。然而，为轴运动叙述结束点还有另一个方法。
在逐渐增加的模态 (普遍被 G91 指定) 中，运动的结束点指出，从工具的现在位置被指定, 而表示不是零点。因为有指挥运动的这一个方法, 程序师必须总是问 "我应该移动工具多远? ” 当有时候逐渐增加的模态可能是非常有帮助的，一般来说，这应是叙述运动和初学者的更讨厌和更困难的方法，应该专注于使用绝对的模态。
当编写运动指令的时候，要小心。初学者应逐渐增加地去考虑的运动的趋向。如果是在绝对的模态 (如初学者) 中的工作，程序师总是应该考虑 "到什么位置工具应该被移动吗? ” 这一个位置应该和零点相关，而不是与工具现在的位置相关。
除了使任何的指令决定现在的位置是非常容易的之外, 在绝对的模态中工作的另一种好处是可以在运动指令期间处理所犯的错误。在绝对的模态中，如果一个在程序的指令中运行错误，那么只有一个运动是不正确的。从另外一个方面来说，如果一个错误在逐渐增加的运动期间发生，来自错误的点的所有的运动也将会是不正确的。
3. 分配程序零点
务必清醒地意识到， CNC 控制必须指出零点的位置，可以通过一种或者多种的方法。
如何处理，引人注目的改变CNC 机器和控制另外的机器，一个方法是分配程序的零点进入程序中。通过这种方法，程序员会告诉控制器从零点到机器开始的地方
有多远。这些一般在G92 (或者G50) 指令在程序的开头或者在每个工具的开头完成。
另外，更新和更好的方法来安排程序零点是通过一些偏移量的形式来安排。一般情况，机器控制中心呼叫偏移量，习惯以程序零点固定装置来弥补。旋转中心的制造者一般呼叫偏移程序零点对于每个工具的几何偏移。更多关于程序零点用以安排的零点将会在第四点那里的概念有所呈现。
4. 关于轴运动的其他点
对这点, 我们的主要关心是该如何决定每个运动指令的结束点。你应该已经知道，做这些需要明白了解矩形同等的系统。然而，有其他的因数关系到运动怎么样发生。例如，运动的类型（迅速的, 直线, 圆形的, 及其他.) ，运动的速率，还有程序本身。我们将会在第三点的概念那里讨论这些其他的考虑。
5. 告诉机器该如何运行CNC 程序
几乎所有现在的 CNC 控制使用一个字格式作为编程。(唯一的例外对这是特定的会话控制。) 由字格式, 我们意指 CNC 的程序像句子一样的指令组成. 每个指令由 CNC 字组成.
每个 CNC 字有一个字母地址和数字的值。字母地址 (X ，Y ，Z, 及其他.) 告诉控制字和数字的值类型和告诉控制字的数值。 就像运用的英语中的词和句子一样，一个 CNC 指令的字告诉 CNC 机器我们想要目前做的目的。
一个很好的例子，就像一个 CNC 程序中的在一步一步地指导。举个例子，你有一些采访者将来到这个城镇来参观你的公司。你需要写下从本地机场到你公司的详细路线说明。为了做好，你必须首先可以指引从机场到你公司的路径。然后，接下来，写下每次的说明。
那些人可以根据你的说明将可以完成第一步然后下一步，直到他或者她到达你的公司。
相似的样子, 一个 CNC 程序师一定能够看得见机制操作是在程序的执行期间被运行. 然后, 在一步一步地次序中, 程序师将会提供一系列指令适当地使机器的行为表现为连续。
正如发展旅行的人一定能够使拿的路径看得见，因此，必须使 CNC 程序师能够在一个程序是否成功地发展之前， CNC 机器将会产生的运动看得见。没有这
一种使看得见的能力, 程序师将不能够正确地在程序中命令轴运动。这是为什么机械师制造最好的 CNC 使用者的一个理由。一个富有经验的机械师应该能够容易地使任何的机制操作发生。
正如每个简洁的旅行指引，将会由一个句子组成。每个指引也会在一个 CNC 程序里面由一个指令组成。正如旅行指引的句子由字 (用英语) 组成, 也是被由 CNC 字组成的 CNC 指令 (以 CNC 语言) 。
跟随你的旅行指引的人将会明确旅游观光路线。如果你的指引路线出现错误, 被指引的人将会在前往你的公司的途中迷路。相似的例子, CNC 机器将会明确地运行一个 CNC 程序，如果在程序中有一个错误, ，CNC 机器将不能正确地执行任务。
当字和指令在这一个程序中或许没有让你引起注意 (仍然) 的时候, 要记得我们正在强调在 CNC 程序将会依据的指令的次序继续运行。控制系统将会首先写入，编译和运行程序中的第一指令，然后才执行下一步。控制系统就是不断地写入，编译，运行重复这些动作。然后跳到下一条指令。控制会继续在程序中平衡地继续的运行。同样，要注意给出的一步一步的指令。
6，关于程序的说明
就像程序是由指令组成一样，指令也是由一大串字来组成。每个字有一个字住址和数字值。字住址告诉控制字类型， CNC 控制器的制造者决定字名称 (字住址) 和他们的含义。CNC 初学编程者必须叁考控制制造者程序手册所定义的字名字和意义。这里是一本关于一些字类型的简短目录和他们的通常字住址。
7. M-各种功能 (在下面见到)
正如你所见, 许多字住址以相当合乎逻辑的形式来选择 (T 为工具， S 为纱锭， F 为同盟的, 及其他.). 一些需要记住.
有两种字地址(G 和 M).被允许指定特别的功能。(G) 普遍用来设定模态，我们已经介绍了被 G90 指定的绝对模态和被 G91 指定的逐渐增加的模态。有且只有两个预备的功能可用。你必须叁考你的控制制造者的手册，查找预备功能的目录, 还有你的机器的各种特别功能。
相似的预备功能, 各种的功能 (M 字) 允许多种特别的功能。各种的典型功能被来当设计的开关 (相似的纱锭 ON/OFF ，冷冻剂 ON/OFF, 等等). 他们也
用做CNC 机器工具的允许的许多其他可设计功能的编程。
对一位初学者, 好象CNC 的编程要记住很多东西。但实际上在CNC 编程中真正所用到的也只有大概30-40个不同的字。如果你把CNC 的编程看成像学习外语一样，它也就是40个字而已，那么学习起来不应该有困难。