lesson数字控制.doc

第49课 数字控制 Lesson 49 Numerical Control One of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control(NC). Prior to the advent [‘?dv?nt] of NC, all machine tools were manually operated and controlled. Among the many limitations associated with manual control machine tools, perhaps none is more prominent突出的，显著的than the limitation of operator skills. With manual control, the quality of the product are directly related to and limited to the skills of the operator. Numerical control represented the first major step away from human control of machine tools. 先进制造技术中的一个最基本的概念是数字控制(NC)。在数控技术出现之前, 所有的机床都是由人工操纵和控制的。在与人工控制的机床有关的很多局限性中,操作者的技能大概是最突出的问题。采用人工控制时, 产品的质量直接与操作者的技能有关。数字控制代表了从人工控制机床走出来的第一步。数控（英文名字：Numerical Control 简称NC）技术是指用数字、文字和符号组成的数字指令来实现一台或多台机械设备动作控制的技术。1952年，第一台数控机床问世，成为世界机械工业史上一件划时代的事件，推动了自动化的发展。现在，数控技术也叫计算机数控技术（CNC，Computerized Numerical Control）。这种技术用计算机按事先存贮的控制程序来执行对设备的运动轨迹和外设的操作时序逻辑控制功能。prominent 1.important; famous重要的；卓越的，著名的 She was a prominent member of the city council. 她是市政会重要人物。 2.projecting from something 突起的，凸出的 A man with big, prominent eyes like a bulls. 有公牛一样突眼的大眼睛男子。 3.outstanding; noticeable显眼的，显著的；突出的 The new housing estates are prominent landmarks. 新住宅群是显著的地标。 Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions符号指令. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions操纵指令 to the machine tool. For a machine tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader. 数字控制意味着采用预先录制的、存储的符号指令来控制机床和其他制造系统。一个数控技师的工作不是去操纵机床,而是编写能够发出机床操纵指令的程序。对于一台数控机床,其上必须安有一个被称为阅读机的界面装置,用来接受和解码出编程指令。rather than (要)…而不…, 与其…倒不如… 1. Well have the meeting in the classroom rather than in the hall. 我们与其在教室里开会, 不如在礼堂开会。 2. They thus increased their grain production rather than diminished it