Unit 3数控编程
Unit 3 Programming for Numerical Control
A program for numerical control consists of a sequence of directions that causes an NC machine to carry out a certain operation, machining being the most commonly used process. Programming for NC may be done by an internal programming department, on the shop floor, or purchased from an outside source. Also, programming may be done manually or with computer assistance.数控编程由一系列方向构成，这些方向导致数控车床执行某种操作，加工是最常用的进程。数控车床编程由内部编程部门来完成，在车间里，或者从外部源购买。编程还可以手动或者在计算机辅助下来完成。
The program contains instructions and commands. Geometric instructions pertain to relative movements between the tool and the workpiece. Processing instructions pertain to spindle speeds, feeds, tools, and so on. Travel instructions pertain to the type of interpolation and slow or rapid movements of the tool or worktable. Switching commands pertain to on/off position for coolant supplies, spindle rotation, direction of spindle rotation, tool changes, workpiece feeding, clamping, and so on.
程序包括指令和命令。几何指令涉及刀具和工件间的相对移动。进程指令涉及主轴速度，进给以及道具等。行动指令涉及插值的类型以及刀具或者工作台的缓慢和快速移动。切换命令涉及到开/关冷却液供给状况，主轴旋转，主轴方向，换刀，工件进给，夹具固定等等。
(1) Manual programming. Manual part programming consists first of calculating the dimensional relationships of the tool, workpiece, and worktable, based on the engineering drawings of the part, and manufacturing operations to be performed and their sequence. A program sheet is then prepared, which consists of the necessary information to carry out
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the particular operation, such as cutting tools, spindle speeds, feeds, depth of cut, cutting fluids, power, and tool or workpiece relative positions and movements. Based on this information, the part program is prepared. Usually a paper tape is first prepared for trying out and debugging the program. Depending on how often it is to be used, the tape may be made of more durable mylar.
（1）手工编程。手工编程包括根据部分工程图纸首先算出刀具，工件以及工作台的尺寸关系，继而决定执行的操作和工序。那么一个包括执行特定操作所需必要信息的程序表就准备好了，例如刀具切削，主轴转速，进给，切削深度，切削液，以及刀具或者工件间的相对位置或者移动。根据这些信息，部分程序就准备好了。通常一个纸带首先被准备好用于试用和调试程序。根据纸带被使用多久，纸袋通常用更耐用的聚酯薄膜制成。
Manual programming can be done by someone who is knowledgeable about the particular manufacturing process and is able to understand, read, and change part programs. Because they are familiar with machine tools and process capabilities, skilled machinists can do manual programming with some training in programming. However, the work involved is tedious, time-consuming, and uneconomical consequently, manual programming is used mostly in simple point-to-point applications.
手工编程可以由那些具有特定制造工艺知识和能够理解，阅读以及更改部分程序的人来完成。因为他们熟悉机床刀具和工艺流程，熟练的机械师可以做一些手工编程的编程培训。然而，所涉及的工作是乏味的，费时的，因此不合算。手工编程大多数用于简单的点对点应用上。
(2) Computer-aided programming. Computer-aided part programming involves special symbolic programming languages that determine the coordinate points of corners, edges, and surfaces of the part. Programming language is the means of communicating with the computer
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and involves the use of symbolic Characters. The programmer describes the component to be processed in this language, and the computer converts it to commands for the NC machine. Several languages having various features and applications are commercially available. The first language that used English-like statements was developed in the late 1950s and is called APT (for Automatically Programmed Tools). This language, in its various expanded forms, is still the most widely used for both point-to-point and continuous-path programming.（2）计算机辅助编程。计算机辅助编程是一种涉及到特殊符号的编程语言，这种语言可以决定角点的坐标，刀口以及工件的表面。编程语言是与计算机通信的方式并且涉及到符号字符。编程员用这种语言描述加工零件，而由计算机将零件程序转换为数控机床的执行指令。许多种商业应用上的语言有多种多样的特点和应用。第一种被使用的是类似于英语语句的语言，它在十九世纪五十年代末被开发出来并被称为APT语言。这种语言，由于它多种多样的扩展形式，一直是最广泛的用于点对点和连续路径编程的语言。
Complex parts are now machined using graphics-based, computer-aided machining programs. A tool path is created in a largely graphic environment that is similar to a CAD program. The machine code (G-Code) is created automatically by the program. 复杂的工件现在使用基本的绘图进行制造，计算机辅助制造程序。刀具的路径是在类似于一个CAD程序的大量的绘图环境下制造出来的。这种机器代码由程序自动生成。
Before production begins, the programs should be verified, either by viewing a simulation of the process on a monitor or by making the part from an inexpensive material (such as aluminum, wood, wax, or plastic), rather than from the actual material specified for the finished part. 在生产开始之前，程序应该被校验，还有就是通过一个显示器观看工艺流程的模仿或者使用廉价的材料（例如铝，木头，石蜡，或者是塑料）制作工件，而不是使用指定用于已加工零件
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的真实材料。
Computer-aided part programming has the following significant advantages over manual methods:
计算机辅助编程有以下几个优于人工方式的重要优点。 ● Relatively easy use of symbolic language.
● Reduced programming time. Programming is capable of accommodating a large amount of data concerning machine characteristics and process variables, such as power, speeds, feed, tool shape, compensation for tool shape changes, tool wear, deflections, and coolant use.
● Reduced possibility of human error which can occur in manual programming.
● Capability of simple changeover of machining sequence or from machine to machine.
● Lower cost because less time is required for programming. 比较容易使用的符号语言
缩短了编程时间。编程是一种容纳了大量关于机械特点和工艺变量数据的一种能力，例如动力，速度，进给，刀具形状，刀具形状改变的补给量，刀具磨损，偏转，以及冷却液的使用。 减少了在人工编程中出现人为错误的可能性。 因为编程时所需更少的时间，降低了成本。
The use of programming languages not only results in higher part quality but also allows for more rapid development of machining instructions. In addition, simulations can be run on remote computer terminals, to ensure that the program functions as intended. This method prevents unnecessary occupation of expensive machinery for debugging procedures. 编程语言的使用不仅导致更高的工件质量而且考虑到了机械指令的更加快速发展。另外，模拟可以
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在远程计算机的终端设备上运行，这就确保了程序按照既定来运行。这种方法可以防止昂贵的机器由于调试程序产生不必要的占用。
Selection of a particular NC programming language mainly depends on the following factors: 选择某一种数控机床编程语言主要取决于以下几个因素：
● Level expertise of the personnel in the manufacturing facility ● Complexity of the part
● Type of equipment and computers available
● Time and costs involved in programming 生产设施人员的专业水平级别 工件的复杂程度
设备的外形以及计算机的应用 涉及编程的时间及费用
Because numerical control involves the insertion of data concerning workpiece materials and processing parameters, programming must be done by operators or programmers who are knowledgeable about the relevant aspects of the manufacturing processes being used. Before production begins, programs should be verified, either by viewing a simulation of the process on a CRT screen or by making the part from an inexpensive material, such as aluminum, wood, or plastic, rather than the material specified for the finished part.
（无英语）因为数控涉及有关工件材料和加工参数的数据插入，编程必须由有制造业的相关方面知识的操作工和程序员来完成。在生产开始之前，程序应该被校验，还有通过一个CRT屏幕来观察工艺流程的模拟或者用廉价的材料制造工件，例如铝，木头或者塑料，而不是使用指定用于已加工零件的真实材料。
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