数控技术外文文献翻译、中英文翻译

1、 numerical control technologyNUMERICAL CONTROLNumerical control(NC)is a form of programmable automation in which the processing equipment is controlled by means of numbers，letters，and other symbolsThe numbers，letters，and symbols are coded in an appropriate format to define a program of instructions

2、for a particular workpart or jobWhen the job changes，the program of instructions is changedThe capability to change the program is what makes NC suitable for low-and medium-volume productionIt is much easier to write programs than to make major alterations of the processing equipmentThere are two ba

3、sic types of numerically controlled machine tools：pointtopoint and continuouspath(also called contouring)Pointtopoint machines use unsynchronized motors，with the result that the position of the machining head Can be assured only upon completion of a movement，or while only one motor is runningMachine

4、s of this type are principally used for straightline cuts or for drilling or boring The NC system consists of the following components：data input，the tape reader with the control unit，feedback devices，and the metalcutting machine tool or other type of NC equipmentData input，also called“mantocontrol

5、link”，may be provided to the machine tool manually，or entirely by automatic meansManual methods when used as the sole source of input data are restricted to a relatively small number of inputsExamples of manually operated devices are keyboard dials，pushbuttons，switches，or thumbwheel selectorsThese a

6、re located on a console near the machineDials ale analog devices usually connected to a syn-chro-type resolver or potentiometerIn most cases，pushbuttons，switches，and other similar types of selectors aye digital input devicesManual input requires that the operator set the controls for each operationI

7、t is a slow and tedious process and is seldom justified except in elementary machining applications or in special casesIn practically all cases，information is automatically supplied to the control unit and the machine tool by cards，punched tapes，or by magnetic tapeEightchannel punched paper tape is

8、the most commonly used form of data input for conventional NC systemsThe coded instructions on the tape consist of sections of punched holes called blocksEach block represents a machine function，a machining operation，or a combination of the twoThe entire NC program on a tape is made up of an accumul

9、ation of these successive data blocksPrograms resulting in long tapes all wound on reels like motion-picture filmPrograms on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loopOnce installed，the tape is used again and again without further handlingI

10、n this case，the operator simply loads and unloads the partsPunched tapes ale prepared on type writers with special tapepunching attachments or in tape punching units connected directly to acomputer systemTape production is rarely error-freeErrors may be initially caused by the part programmer，in car

11、d punching or compilation，or as a result of physical damage to the tape during handling，etcSeveral trial runs are often necessary to remove all errors and produce an acceptable working tape While the data on the tape is fed automatically，the actual programming steps ale done manuallyBefore the coded

12、 tape may be prepared，the programmer，often working with a planner or a process engineer, must select the appropriate NC machine tool，determine the kind of material to be machined，calculate the speeds and feeds，and decide upon the type of tooling needed. The dimensions on the part print are closely e

13、xamined to determine a suitable zero reference point from which to start the programA program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specificationsThe control

14、 unit receives and stores all coded data until a complete block of information has been accumulatedIt then interprets the coded instruction and directs the machine tool through the required motionsThe function of the control unit may be better understood by comparing it to the action of a dial telep

15、hone，where，as each digit is dialed，it is storedWhen the entire number has been dialed，the equipment becomes activated and the call is completedSilicon photo diodes，located in the tape reader head on the control unit，detect light as it passes through the holes in the moving tapeThe light beams are co

16、nverted to electrical energy，which is amplified to further strengthen the signalThe signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drivesSome photoelectric devices are capable of reading at rates up to 1000 characters per secondHigh re

17、ading rates are necessary to maintain continuous machinetool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operationsThe reading device must be capable of reading data blocks at a rate faster than the control system can process the dataA feedback device is

18、 a safeguard used on some NC installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine toolAn NC machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop systemPositionin

19、g control is accomplished by a sensor which，during the actual operation，records the position of the slides and relays this information back to the control unitSignals thus received ale compared to input signals on the tape，and any discrepancy between them is automatically rectifiedIn an alternative

20、system，called an openloop system，the machine is positioned solely by stepping motor drives in response to commands by a controllersThere are three basic types of NC motions, as follows: Point-to-point or Positional Control In point-to-point control the machine tool elements (tools, table, etc.) are

21、moved to programmed locations and the machining operations performed after the motions are completed. The path or speed of movement between locations is unimportant; only the coordinates of the end points of the motions are accurately controlled. This type of control is suitable for drill presses an

22、d some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece. Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate s

23、uitable 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 ca

24、n be machined. This type of controlled motion is often referred to as linear control or a half-axis of control. Machines with this form of control are also capable of point-to-point control.Continuous Path or Contouring Control In continuous path control the motions of two or more of the machine axe

25、s 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

26、 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 four-or five-or even si

27、x-axis 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,

28、 in NC terminology an axis of control is any controlled motion of the machine elements (spindles, tables, etc). A further complication is use of the term half-axis of control; for example, many milling machines are referred to as 2.5-axis machine. This means that continuous control is possible for t

29、wo motions (axes) and only linear control is possible for the third axis. Applied to vertical milling machines, 2.5axis control means contouring in the X, Y plane and linear motion only in the Z direction. With these machines three-dimensional objects have to be machined with water lines around the

30、surface at different heights. With an alternative terminology the same machine could be called a 2CL machine (C for continuous, L for linear control). Thus, a milling machine with continuous control in the X, Y, Z directions could be termed be a three-axis machine or a 3c machine, Similarly, lathes

31、are usually two axis or 2C machines. The degree of work precision depends almost entirely upon the accuracy of the lead screw and the rigidity of the machine structureWith this systemthere is no self-correcting action or feedback of information to the control unitIn the event of an unexpected malfun

32、ction，the control unit continues to put out pulses of electrical currentIf，for example，the table on a NC milling machine were suddenly to become overloaded，no response would be sent back to the controllerBecause stepping motors are not sensitive to load variations，many NC systems are designed to per

33、mit the motors to stall when the resisting torque exceeds the motor torqueOther systems are in use，however，which in spite of the possibility of damage to the machine structure or to the mechanical system，ale designed with special hightorque stepping motorsIn this case，the motors have sufficient capa

34、city to“overpowerthe system in the event of almost any contingency The original NC used the closedloop systemOf the two systems，closed and open loop，closed loop is more accurate and，as a consequence，is generally more expensiveInitially，openloop systems were used almost entirely for light-duty applic

35、ations because of inherent power limitations previously associated with conventional electric stepping motorsRecent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applicationsNC technology development trendsSummary : Have introduced num

36、erical control technology and the development trend of the equipment and the current situations of the technical development of numerical control equipment and industrialization of our country of our times briefly , have discussed under the new environment further deepened in our countrys accession

37、to the WTO and opening to the outside world on this basis, develop technology of numerical control of our country and the importance of the information-based level of manufacturing industry of our country and international competitiveness equips , improves, and has put forward technology of numerica

38、l control of our country and some views equipped of developing from two aspects of strategy and tactics.The engineering level of equipment industry and modernized intensity are determining the level of the whole national economy and modernized intensity , numerical control technology and equip , dev

39、elop new developing new high-tech industry and most advanced industry To can make technology and basic equipment most (national defense industry industries , such as information technology and their industry , biotechnology , industry , aviation , spaceflight ,etc. ). Marx has ever said the differen

40、ces of different economic times, do not lie in what is produced, lie in how produce, with what means of labor produce . Manufacturing technology and equipping the most basic means of production that are that the mankind produced the activity, and numerical control technology to equip most central te

41、chnology. Nowadays the manufacturing industry all around the world adopts the technology of numerical control extensively; in order to improve manufacturing capacity and level, improve the adaptive capacity and competitive power to the changeable market of the trends. In addition every industrially

42、developed country in the world also classifies the technology and numerical control equipment of numerical control as the strategic materials of the country, not merely take the great measure to develop ones own numerical control technology and industry, and implement blockading and restrictive poli

43、cy to our country in high-grade, precision and advanced key technology and equipment of numerical control. In a word, develop taking technology of numerical control as the core advanced manufacturing technology become world all developed country; accelerate economic development already in a more cos

44、t-effective manner, important route to improve the comprehensive national strength and national position.Numerical control technology to go on technology that control with digital information to mechanical movement and working course, numerical control equipment whether represented by technology of

45、numerical control new technology make industry and new developing infiltration electromechanics integrated product that form of manufacturing industry to tradition, i.e. what is called 马棚网 gitization equip, its technological range covers a lot of fields: (1)Mechanical manufacturing technology; (2)In

46、formation processing , processing , transmission technology; (3)Automatic control technology; (4)Servo drive technology; (5)Transducer technology; (6)Software engineering ,etc. 1 Development trend of a numerical control technologyThe application of the technology of numerical control has not only br

47、ought the revolutionary change to traditional manufacturing industry, make the manufacturing industry become the industrialized symbol , and with the constant development of the technology of numerical control and enlargement of application, the development of he some important trades (IT , car , li

48、ght industry , medical treatment ,etc. ) to the national economy and the peoples livelihood plays a more and more important role, because these trade necessary digitization that equipped has already been the main trend of modern development. According to the technology of numerical control and equip

49、ment development trend in the world at present, its main research focus has the following several respect 14.1.1 A high-speed , high finish machining technology and new trend equippedEfficiency, quality are subjects of the advanced manufacturing technology. At a high speed, high finish machining tec

50、hnology can raise the efficiency greatly, quality and grade to raise product, shorten production cycle and improve the competitive power of market. Japan carry technological research association classify their as one of the 5 loud modern manufacturing technologies first for this reason, learn (CIRP

51、) to confirm it as the centre in the 21st century to study one of the directions in international production engineering. In the field of car industry, produce 40 second when beat such as production of 300,000 / vehicle per year, and many variety process it is car that equip one of the key problems

52、that must be solved; In the fields of aviation and aerospace industry, its processings spare parts are mostly the thin wall and thin muscle, rigidity very bad, material aluminum or aluminum alloy, in high to cut pace and cut strength very under the little situation only, could process these muscles,

53、 walls. Adopt large-scale whole aluminium alloy blank method of pay empty make the wing recently, large-scale parts such as the fuselage ,etc. come to substitute a lot of parts to assemble through numerous rivet , screw and other connection ways, make the intensity , rigidity and dependability of th

54、e component improved. All these requirement for processing and equipping and proposing high-speed , high and precise and high flexibility.According to EMO2001 exhibition situation, the high-speed machining center enters for the pace to can reach 80m/min, even high; air transport competent pace can r

55、each 100m/min about. A lot of car factories in the world at present, including Shanghai General Motors Corporation of our country, adopt, substitute and make the lathe up with high-speed machining center production line part that make up already. HyperMach lathe of Company , CINCINNATI of U.S.A. , e

56、nter , give pace to be most loud to reach 60m/min, it is 100m/min to be fast, acceleration reach 2g, the rotational speed of the main shaft has already reached 60 000r/min. Processing a thin wall of plane parts, spend 30min only, and same part general at a high speed milling machine process and take

57、 3h, process and need 8h with ordinary milling machine; The paces and acceleration of main shaft of dual main shaft lathes of Germany DMG Company reach 12* separately! 000r/mm and 1g. In machining accuracy, in the past 10 years, ordinary progression has accused of the machining accuracy of the lathe

58、 to already improve from 10m to 5m, accurate grades of machining center from 3- 5m, raise to 1- 1.5m, and ultraprecision machining accuracy begin , enter getting nanometer already. In machining accuracy, the past 10 years, ordinary progression accuse of machining accuracy of lathe raise to 5m , from

59、 3- 5m accurate grades of machining center from 10m already, improve to 1- 1.5m, and the ultraprecision machining accuracy has already begun to enter nanometer (0.01m )ly. In dependability, MTBF value of the foreign numerical control device has already reached above 6 000h, MTBF value of the servo system reaches above 30000h, demonstrate very high dependability . For realize at a high speed , high finish machini