《机电工程英语》PPT课件.pptVIP

Lesson 9 The Principle of Numerical Control(NC) 数控技术原理 Section I Words and Phrases Section II Text and Translation Section III Exercises and Answers End Next Section I Words and Phrases craftsman5krB:ftsmEn n.工匠；手艺精巧的 人 variable 5vZEriEbl n.变数，可变物 adj.可变 的,不定的 perform pE5fC:m vt.履行，执行 supervision 7sju:pE5viVEn n.监督，管理 via 5vaiE, 5vi:E prep.通过，经由 constitute 5kCnstitju:t vt.制度，建立 identical ai5dentikEl adj.同一的，同样的 flexibility 7fleksE5biliti n.弹性，适应性 Topic Above Next End Section I Words and Phrases spindle 5spindl n.轴，锭子 drill dril n.钻孔机，钻子，军事训练，（反复） 练习；v.训练，钻孔 lathe leiT n.车床；vt.用车床加工 milling 5miliN n.磨, 制粉, 机轧齿边 grinder 5raindE n.磨工, 尤指磨刀具的工人, 脱衣舞女演员 vertical 5vE:tikEl adj.垂直的；n.垂直线, 垂直 面, 竖向 horizontal 7hCri5zCntl adj.地平线的, 水平的 inspection in5spekFEn n.检查，视察 Topic Above Next End Section I Words and Phrases assembly E5sembli n.集合，装配，集会，集结 ，汇编 rotaterEu5teit v.(使)旋转 mechanism 5mekEnizEm n.机械装置，机构， 机制 auxiliary C:5ziljEriadj.辅助的，补助的 hydraulic hai5drC:likadj.液压的 lubrication 7lu:bri5keiFEn n.润滑油 column 5kRlEm n.立柱 magazine 7mAE5zi:n n.刀库；杂志 majority mE5dVCriti n.多数 intervention 7intE(:)5venFEn n.干涉 Topic Above Next End Section I Words and Phrases numerical control（NC） 数字控制 a punched tape穿孔纸带 turning center 切削中心 vertical-spindle machine center卧式加工中心 horizontal-spindle machine center 立式加工中心 electrical discharge machine 电火花加工机床 flame cutter线切割机床 serve drive system 伺服驱动系统 lead screw 丝杠，螺杆 automatic tool changer（ATC） 自动换刀装置 Topic Above Next End Section II Text Early machine tools were operated by craftsmen who decided many variables such as speeds, feeds, and depth of cut, etc1. With the development of science and technology, a new term, numerical control (NC) appeared. Controlling a machine tool using a punched tape or stored program is known as numerical control. When numerical control is performed under computer supervision, it is called computer numerical control (CNC). Computers are the control units of CNC machines, they are built in or linked to the machines via communications channels. CNC means the operation of machine tools and other processing machines by a series of commands of the tool to the work-piece2. An organized list of commands constitutes a CNC program. The program may be used repeatedly to obtain identical results. When the job changes, we can only change the program of instructions. The capability to change the program for each new job gives CNC its flexibility. Topic Above Next 汉 End Section II Text CNC technology is being used on all types of machine tools, from the simplest to the most complex, including the single-spindle drilling machine, lathe and turning center, vertical or horizontal-spindle machine center and milling machine , punches, electrical discharge machines (EDM), flame cutters, grinders, and testing and inspection equipment3. CNC machine tools are complex assemblies. However, in general, Figure3-1 shows how any CNC machine is to work: Topic Above Next 汉 End Prog- ram Prog- ram Prog ram Numerical Controlled device Serve drive system Machine Measure device Feed back Fig3-1 CNC Structure Section II Text Through the figure 3-1, we can see any CNC machine tool consists of the followings units: CNC device: Serve drive system: including driver and serve motor Machine: 1.CNC device As with all computers, the CNC device works on a binary principle using only two characters 1 and 04. Series of ones and zeros which is so-called machine language is the only language the computer understands. When creating the program, operators use a list of codes and keys to express the job information. After inputting the program, CNC device will first compile it into machine language with special Topic Above Next 汉 End Section II Text built-in software, then the computer will calculate all the points and send out the control commands (electronic pulse signals) to serve drive system5. 2.Serve drive system This system includes drives and serve motors, Which is the bridge connecting CNC device and machine. Drives transform pulse signals sent out from CNC device into motor signals, which tell the serve motor to rotate with each pulse6. The rotation of the serve motor in turn rotates the lead screw which drives the linear axis. With each step of movement, the measure device sends a signal back to CNC device, which compares the current position of the drive axis with the programmed position. Topic Above Next 汉 End Section II Text 3.Machine The mechanism of numerical control machine tools consists of two parts. Except the common parts, such as the host movement part, the feed movement part (work table, tool rest), the auxiliary body (hydraulic, cooling and lubrication apparatus ) and the strut part (lathe bed, column) and so on, it also includes some special parts, like magazines and automatic tool changers7. Most of the time, several different cutting tools are used to produce a part. The tools must be replaced quickly for the next machining operation. For this reason, the majority of CNC machine tools are equipped with automatic tool changers. They allow tool changing without the intervention of the operator. Typically, an automatic tool changer grips the tool in the spindle, pulls it out , and replaces it with another tool. On most Topic Above Next 汉 End Section II Text machines with automatic tool changers, the magazine can rotate in eithedirection, forward or reverse(fig.3-2). Topic Above Next 汉 End Fig3-2 The ATC used most often Section II Translation Topic Above Next 英 End 老式机床通常是由工人操作并由他们决定机床速度、进给量 、切削深度等。随着科学技术的发展，一个新术语-数字控制（ NC）诞生了。数字控制就是利用穿孔纸带或存储的程序来控制机 床。当数控机床在计算机监控下工作时，它就被称为计算机数控 机床。计算机是CNC机床的控制单元，它们内嵌于数控机床中或通 过通信渠道与数控机床相连。CNC就是通过一系列的刀具与工件的 动作指令来实现机床或其他加工设备的操作。这些指令的有序组 织构成了一个数控程序，该程序可重复使用而获得完全一致的结 果。只需修改程序指令就可得到新的零件，这种能力给CNC带来灵 活性。 从最简单到最复杂的机床都会用到数控技术，包括单轴钻床 、车床和车削中心、铣床和立式或卧式加工中心、冲床、电火花 加工机床、线切割机床、磨床以及测试检测装置等。 Section II Translation CNC机床结构较为复杂，然而，一般来说，任何CNC机床的 工作过程都可由图3-1表示。 通过上图，我们可以看出一台数控机床包括了下面几部分： 数控系统；伺服驱动系统，包括驱动器和伺服电机；机床本体。 Topic Above Next 英 End 数控程序数控系统 伺服驱 动系统 机床本体 检测装置 反馈 Section II Translation 1、数控系统 象所有的计算机一样，数控系统只能工作在仅由0和1组成的二进制 下。由一系列0和1构成的机器语言是计算机唯一能识别的语言。编程的 时候，操作人员用一段段的代码和指令来表达工件的信息。将程序输入 后，数控系统通过内部的软件首先将其编译成机器语言，然后计算机将 计算各坐标点，并送出控制命令（电子脉冲信号）到伺服驱动系统。 2、伺服驱动系统 此系统包括驱动器和伺服电机，它是连接数控系统和机床本体的桥 梁。驱动器将数控装置送出的脉冲信号转化成电机信号，此信号控制伺 服电机跟随脉冲信号而旋转。电机旋转反过来又带动丝杠旋转，从而控 制各线性轴的运行。随着每一步的运行，检测装置将各轴当前位置信号 送回数控装置，数控装置将反馈信号和编程的位置值进行比较从而调整 它的输出信号。 Topic Above Next 英 End Section II Translation 3、机床本体 数控机床的机械结构包括两部分。除了主运动部件、进给运 动部件（工作台、刀架）、辅助部分（液压、冷却和润滑部分等 ）和支撑部件（床身、立柱）等一般部件外，还有些特殊部件， 如刀库和自动换刀装置等。通常加工一个零件需要使用几把不同 的刀具。加工过程中必须为下一步加工工序迅速换刀。为此，大 部分CNC机床配备了自动换刀装置。它们无需操作者干预，即可 换刀。较为典型的是，自动换刀装置会卡紧车床主轴内的刀具， 将其拉出，然后用另一把刀具代替。在具有自动换刀装置的大部 分机床上，刀架可以进行旋转，或正向反向均可（图略）。 Topic Above Next 英 End Section III Exercises . Answer the following questions according to the text. 1.What is the difference between the early machine tools and the NC machine tools? 2.Give the list of NC/CNC technology in application. 3.After inputting the program, what CNC device will do? 4.What is the function of the measure device? 5.Why are the majority of CNC machine tools equipped with automatic tool changers? Topic Above Next 答 End Section III Exercises . Review the text and translate the following phrases into Chinese or English. 1. machine tool 7. 电火花加工机床 2. numerical control（NC） 8. 线切割机床 3. a punched tape 9. 伺服驱动系统 4. turning center 10.卧式加工中心 5. lead screw 11.立式加工中心 6. work table 12.自动换刀装置 . Topic Above 答Next End Section III Exercises .Translate the following sentences into Chinese. 1.Controlling a machine tool using a punched tape or stored program is known as numerical control. 2.The capability to change the program for each new job gives CNC its flexibility. 3.After inputting the program, CNC device will first compile it into machine language with special built-in software. 4.The rotation of the serve motor in turn rotates the lead screw which drives the linear axis. 5.Most of the time, several different cutting tools are used to produce a part. Topic Above 答Next End Appendix Topic Above Next Return End 1.Early machine tools were operated by craftsmen who decided many variables such as speeds, feeds, and depth of cut, etc. 老式机床通常是由工人操作并由他们决定机床速度、进给量、切削深度等 。 2.CNC means the operation of machine tools and other processing machines by a series of commands of the tool to the work-piece. CNC就是通过一系列的刀具与工件的动作指令来实现机床或其他加工设备 的操作。 3.CNC technology is being used on all types of machine tools, from the simplest to the most complex, including the single-spindle drilling machine, lathe and turning center, vertical or horizontal-spindle machine center and milling machine , punches, electrical discharge machines (EDM), flame cutters, grinders, and testing and inspection equipment. Appendix 从最简单到最复杂的机床都会用到数控技术，包括单轴钻床、车床和 车削中心、铣床和立式或卧式加工中心、冲床、电火花加工机床、线 切割机床、磨床以及测试检测装置等。 4. As with all computers, the CNC device works on a binary principle using only two cha