Numerical Control and NC Tools——数字控制和数控机床

发布日期:[10-11-28 16:51:47] 浏览人次:[]

5    Numerical Control and NC Tools

A    Numerical control

Numerical control refers to the operation of machine tools form numerical data stored on paper or magnetic tape, tabulating cards, computer storage disks, or direct computer information. A historical example of using instructions punched on paper tape is the player piano. Notes to be played (instructions) are defined as a series of holes on a piano roll (punched paper tape), then sensed by the piano (using a pneumatic system powered by a foot-operated bellows), which plays the notes (executes the instructions).

Because mathematical information is used, the concept is called numerical control (NC). NC is the operation of machine tools and other processing machines by a series of the tool too the workpiece. An organized list of commands constitutes an NC program. The program may be used repeatedly to obtain identical results. Manual operation of machine tools may be unsurpassable in producing fine-quality work, but such qualities are not consistent. NC is not a machining method; it is a means for machine control. NC is considered as one of the most dramatic and productive developments in manufacturing in this century.

identical 相同的、一样的 adj.

note 音符 n

instruction 指令 n

pneumatic 风动的;气动的 adj.

power 提供动力 v

punch 冲孔 v

sense 检测,辨别 v

tabulate 平面的,列表的 adj.

unsurpassable 无法超越的 adj.

coded instruction 编码指令

fine-quality 优质

manual operation 手动操作

numerical control 数控

relative positioning 相对定位

tabulating card 列表卡,magnetic tape 磁带,paper tape 纸带:均为早期使用过的出具或程序记录媒介,现在已基本被淘汰了。

a player piano 这里指"可自动弹奏的钢琴"

foot-operated bellows 用脚控制的鼓风管

an NC program 一个NC程序

B    Numerical Control Tools

Early NC design placed control units on existing machine tool structures to accomplish numerical control. As experience was gained, it was apparent that NC machines were more efficient in the overall operation than conventional machines. But the controls became more adaptable to production equipment. Inspection, pipe bending, flame cutting, wire-wrapping, circuit board stuffing of electronic chips, laser cutting of fabric, drafting machines, and production processes have proven applications. In some instances the added controls cost more than the basic machine tool, but it is often a worthwhile expense. Solid-state circuitry has provided more reliable control at lower cost than previous electronic technology.

NC should be considered whenever there is similar raw material and work parts are produced in various sizes and complex geometries. Applications are in low-to medium-quantity batches, and similar processing sequences are required on each workpiece. Those production shops having frequent changeovers will benefit.

NC machine tools incorporate many advances such as programmed optimization of cutting speeds and feeds, work positioning, tool s

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