Computer Numerical Controlled Machines,Unit 8,数控机床,CNC machines,华中数控面板,数控机床,CNC Machines,Unit 8 CNC machines Early machines 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 (NC). NC has been defined by the Electronic Industries Association (EIA) as “A system in which actions are controlled by the direct insertion of numerical data at some point. The system must automatically interpret at least some portion of this datadj.”.,In the past, machine tools were kept as simple as possible in order to keep their costs down. Because of the ever-rising cost of labor, better machine tools, complete with electronic controls, were developed so that industry could produce more and better goods at prices that were competitive with those offshore industries. NC is being used on all types of machine tools, from the simplest to the most complex. The most common machine tools are the single-spindle drilling machine, lathe, milling machine, turning center, and machining center.,1. Single-Spindle Drilling Machine One of the simplest numerically controlled machine tools is the single-spindle drilling machine. Most drilling machines are programmed on three axes: a. The X-axis controls the table movement to the right and left. b. The Y-axis controls the table movement toward or away from the column. c. The Z-axis controls the up or down movement of the spindle to drill holes to depth.,2. Lathe The engine lathe, one of the most productive machine tools, has always been a very efficient means of producing round parts (Fig.7-1). Most lathes are programmed on two axes: a.The X-axis controls the cross motion (in or out) of the cutting tool. b.The Z-axis controls the carriage travel toward or away from the headstock .,3. Milling Machine Fig. 7-2 the vertical knee and column milling machine The milling machine has always been one of the most versatile machine tools used in industry (Fig.7-2). Operations such as milling, contouring, gear cutting, drilling, boring, and reaming are only a few of the many operations that can be performed on a milling machine4. The milling machine can be programmed on three axes: a. The X-axis controls the table movement left or right. b. The Y-axis controls the table movement toward or away from the column. c. The Z-axis controls the vertical (up and down)movement of the knee or spindle.,4. Turning Center Turning Centers were developed in the mid-1960s after studies showed that about 40 percent of all metal cutting operations were performed on lathes. These numerically controlled machines are capable of greater accuracy and higher production rates than were possible on the engine lathe. The basic turning center operates on only two axes: a. The X-axis controls the cross motion of the turret head. b. The Z-axis controls the lengthwise travel (toward or away from the headstock) of the turret head.,5. Machining Center Machining centers were developed in the 1960s so that a part did not have to be moved from machine to machine in order to perform various operations. These machines greatly increased production rates because more operations could be performed on a work-piece in one setup. There are two main types of machining centers, the horizontal and the vertical spindle types. a. The horizontal spindle-machining center operates on three axes: (a) The X-axis controls the table movement left or right. (b) The Y-axis controls the vertical movement (up and down) of the spindle. (c) The Z-axis controls the horizontal movement (in or out) of the spindle. b. The vertical spindle-machining center operates on three axes: (a) The X-axis controls the table movement left or right. (b) The Y-axis controls the table movement toward or away from the column. (c) The Z-axis controls the vertical movement (up and down) of the spindle.,punch pnt n. 冲压机；钻孔机vt. 开洞；以拳重击vi. 用拳猛击 interpret int:prit vt. 说明；口译vi. 解释；翻译 electronic ,ilektrnik adj. 电子的 drill dril n.训练；钻孔机vi. 钻孔；训练 carriage krid n.（机床的）滑板；刀架 headstock hedstk n. 主轴箱 milling mili n. 铣削 contouring knturi n. 成形加工 boring b:ri n. 镗孔；镗削加工 reaming ri:mi n. 铰孔 knee ni: n. 升降台 turning t:ni n. 车削,knee ni: n. 升降台 turning t:ni n. 车削 headstock hedstk n. 主轴承 accuracy kjursi n. 精确性，准确度，精度 work-piece w:kpi:s n. 工件 horizontal hrizntl adj. 水平的 vertical v:tikl adj. 垂直的，直立的 production rate 生产率 numerical control (NC) 数字控制 a punched tape 穿孔纸带,the Electronic Industries Association (EIA) （美国）电子工业协会 drilling machine 钻床 engine lathe 卧式车床 gear cutting 齿轮加工 turning center 切削中心 machining center 加工中心 turret head 转塔头 metal cutting 金属切削 cross motion 横向运动 lengthwise travel 纵向运动,1. Early machines were operated by craftsmen who decided many variables such as speeds,