機械工程專業(yè)英語第11課

1、1TECHNICAL ENGLISHMECHANICAL ENGINEERINGYAN NU211 Computer Numerical ControlCenterpiece：The central or most important feature. And please have a centerpiece for every table. Ball screw 滾珠絲杠副311 Computer Numerical ControlServomotor ：A motor that controls the action of the mechanical device in a servo

2、mechanism.mechanical position or other parameters. For example, an automotive power window control is not a servomechanism, as there is no automatic feedback that controls positionthe operator does this by observation. Servomechanism, is an automatic device that uses error sensing feedback to correc

3、t the performance of a mechanism. The term correctly applies only to systems where the feedback or error-correction signals help control 411 Computer Numerical ControlThe drive system is comprised of screws and motors that will finally turn the part program into motion. The first component of the ty

4、pical drive system is a high-precision lead screw called a ball screw.Screw ：絲杠驅(qū)動系統(tǒng)由絲杠和電動機組成，它最終會把零件加工程序轉(zhuǎn)化為運動。511 Computer Numerical Control Drive motors are the second specialized component in the drive system. The turning of the motor will turn the ball screw to directly cause the machining table

5、to move. Several types of electric motors are used on CNC control systems, and hydraulic motors are also occasionally used.電動機的轉(zhuǎn)動會使?jié)L珠絲杠副轉(zhuǎn)動，并使機床工作臺產(chǎn)生運動。611 Computer Numerical ControlThe simplest type of electric motor used in CNC positioning systems is the stepper motor (sometimes called a stepping m

6、otor). A stepper motor rotates a fixed number of degrees when it receives an electrical pulse and then stops until another pulse is received.步進電機接收到一個電脈沖就會轉(zhuǎn)動一個固定的角度，然后停止轉(zhuǎn)動，直至接收到另一個脈沖。711 Computer Numerical ControlAlternating current (AC) servomotors are currently the standard choice for industrial C

7、NC machine tools.Alternating current servomotor 交流伺服電動機目前，工業(yè)生產(chǎn)中使用的計算機數(shù)控機床上通常選用交流伺服電動機。811 Computer Numerical ControlThe function of a feedback system is to provide the control with information about the status of the motion control system, which is described in Figure 1.Fig.1 Typical motion control

8、system of a CNC machine tool911 Computer Numerical Control There are two main types of control systems: open-loop and closed-loop. An open-loop system does not have any device to determine if the instructions were carried out. For example, in an open-loop system, the control could give instructions

9、to turn the motor 10 revolutions. 主要有兩種類型的控制系統(tǒng)：開環(huán)系統(tǒng)和閉環(huán)系統(tǒng)。開環(huán)系統(tǒng)沒有任何裝置決定是否運行指令。例如，在開環(huán)系統(tǒng)中，控制裝置可以發(fā)出讓電動機轉(zhuǎn)動10轉(zhuǎn)的指令。10Gear Manufacturing Methods Gear planing uses a reciprocating rack, stroking in the direction of the helix on a gear with a gradual generation of form as the rack effectively rolls round the g

10、ear blank. The rack is relieved out of contact for the return stroke as in normal shaping or planing. 刨齒采用往復(fù)運動的齒條刀，當(dāng)齒條刀繞齒輪坯料滾切并沿其螺旋線方向運動時，齒形就會被逐漸展成。與普通的刨削加工相同，在回程中齒條刀與齒輪脫離接觸。11Gear Manufacturing Methods Gear shaping is inherently similar to gear planing but uses a circular cutter instead of a rack a

11、nd the resulting reduction in the reciprocating inertia allows much higher stroking speeds.插齒加工在本質(zhì)上與刨齒加工類似，只是采用了圓形刀具來取代齒條刀，其結(jié)果是減少了往復(fù)運動慣性，在加工過程中可以采用高得多的行程速度。12 Gear hobbing, the most used metal cutting method, uses the rack generating principle but avoids slow reciprocation by mounting many “racks” on a rotating cutter. The “racks” are displaced axially to form a gashed worm. Metal removal rates are high since no reciprocation of hob or workpiece is required.滾齒是最常見的金屬切削方法。它采用齒條展成原理，但是通過安裝在旋轉(zhuǎn)刀