中英文翻譯數(shù)控技術(shù)-預(yù)覽頁
【正文】 r drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece. StraightLine or Linear Control StraightLine control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining. It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined. This type of controlled motion is often referred to as linear control or a halfaxis of control. Machines with this form of control are also capable of pointtopoint control.Continuous Path or Contouring Control In continuous path control the motions of two or more of the machine axes are controlled simultaneously, so that the position and velocity of the can be tool are changed continuously. In this way curves and surfaces can be machined at a controlled feed rate. It is the function of the interpolator in the controller to determine the increments of the individual controlled axes of the machines necessary to produce the desired motion. This type of control is referred to as continuous control or a full axis of control.Some terminology concerning controlled motions for NC machines has been introduced. For example, some machines are referred to as fouror fiveor even sixaxis machines. For a vertical milling machine three axes of control are fairly obvious, these being the usual X, Y, Z coordinate directions. A fourth or fifth axis of control would imply some form of rotary table to index the work piece or possibly to provide angular motion of the work head. Thus, in NC terminology an axis of control is any controlled motion of the machine elements (spindles, tables, etc). A further plication is use of the term halfaxis of control。這種改變程序的能力使數(shù)控適合于中、小批量生產(chǎn)，寫一段新程序遠(yuǎn)比對加工設(shè)備做大的改動容易得多。數(shù)控系統(tǒng)由下列組件組成：數(shù)據(jù)輸入裝置，帶控制單元的磁帶閱讀機(jī)，反饋裝置和切削機(jī)床或其他形式的數(shù)控設(shè)備。撥號盤通常連到一個同步解析器或電位計的模擬裝置上。在傳統(tǒng)的數(shù)控系統(tǒng)中，八信道穿孔紙帶是最常用的數(shù)據(jù)輸入形式，紙帶上的編碼指令由一系列稱為程序塊的穿孔組成。帶子一旦安裝好，就可反復(fù)使用而無需進(jìn)一步處理。通常，必須要試走幾次來排除錯誤，才能得到一個可用的工作紙帶。 裝在控制單元里的紙帶閱讀機(jī)，通過其內(nèi)的硅光二極管，檢測到穿過移動紙帶上的孔漏過的光線，將光束轉(zhuǎn)變成電能，并通過放大來進(jìn)一步加強(qiáng)信號，然后將信號送到控制單元里的寄存器，由它將動作信號傳到機(jī)床驅(qū)動裝置。裝有這種直接反饋檢查裝置的數(shù)控機(jī)床有一個閉環(huán)系統(tǒng)裝置。有幾個理由可以說明步進(jìn)電機(jī)是一個自動化申請的非常有用的驅(qū)動裝置。 一些工業(yè)的機(jī)械手使用高抬腿運(yùn)步的馬乘汽車駕駛員，而且步進(jìn)電機(jī)是有用的在數(shù)字受約束的工作母機(jī)中。在這個系統(tǒng)中，沒有信息反饋到控制單元的自矯正過程。然而，盡管有可能損壞機(jī)床結(jié)構(gòu)或機(jī)械傳動系統(tǒng)，也有使用帶有特高轉(zhuǎn)矩步進(jìn)電機(jī)的其他系統(tǒng)，此時，電動機(jī)有足夠能力來應(yīng)付系統(tǒng)中任何偶然事故。
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