外文翻译--机床坐标轴-数控机床

14. CNC MACHINES Computer Numerical Control machines use a computer to guide a process that might otherwise be done manually. 14.1 MACHINE AXES14.2 NUMERICAL CONTROL (NC) The use of numerical data to drive a machine for processes such as,- milling- turning- drilling- grinding- shot peening- tube bending- flame cutting- automated knitting machines- automatic riveting- etc. Basic components of NC systems,- program- controller unit- machine tool Most suited to,- parts are pr ocessed frequently in small lot sizes- complex part geometry- close tolerances on workpart- many oper ations on part in processing- large amounts of metal to be removed- engineering design will possibly change- parts that are too expensive for mistakes The methods for developing NC programs include,- manual part programming- computer-assisted part programming- computer gener ated programs The manual and computer aided methods use various NC programming languages,- APT (Automatically Programmed Tools)- AUTOSPOT (Automatic System for Positioning Tools)- SPLIT (Sundstrand Processing Language Internally Translated)- COMPACT II- ADAPT (ADaptation of APT)- EXAPT (Extended Subset of APT)- UNIAPT These languages are used by a parts programmer to define the motion of the cutting tool. The languages may be preprocessed, and then used for a number of various control types, such as,- punched paper tape- Computer Numerical Control (CNC)- Direct Numerical Control (DNC) The automatic methods work with geometry created in a CAD program.14.2.1 NC Tapes NC Progr ams are preprocessed on computers, and punched onto paper or mylar tapes. Simple NC machines can use a tape reader to direct the machine. Problems,- required storage, transportation, and manual loading of NC tapes- has to reread the tape for each new part- tapes tend to wear, and become dirty, thus causing misreadings- the mechanical parts in the readers reduced reliability- testing had to be done on the NC machine- no program editing abilities (increased lead time) The end of tapes was the result of two competing developments- DNC used remote computers to replace tape readers, these were displaced in most cases by CNC- CNC allowed the use of a local computer to overcome problems with tapes, and the problems with distant computers. While CNC was used to enhance tapes for a while, they eventually allowed the use of other storage media, and cur rently program transfer media are not required. 14.2.2 Computer Numerical Control (CNC) A computer controller is used to drive an NC machine directly. Characteristics are,- controls a single machine- located very close to machine tool- allows storage/retrieval/entry of NC programs without preprocessing of NC code Advantages of CNC,- progr am is only entered into memory once, so it is more reliable- the programs can be tested and altered at the machine- increased flexibility and control options on the local computer- easy to integrate into FMS systems The Background,- the problems with NC tapes were approached using DNC networks- the communication problems with DNC systems became obvious, and local computers were added to act as tape readers which would read tapes once, and play them back to the NC machine indefinitely- CNC controllers began using other storage media like magnetic tapes, and floppy disks- CNC now offers features like,- local programming,- communication over interfaces,- hard disk storage,- program simulation- etc. ASIDE: Direct Numerical Control is similar to CNC, except a remote computer is used to control a number of machines. This gives the advantage of more computer power. This approach is no longer popular, as the dropping cost of computers offsets any advantages. Some companies use proprietary NC Languages,such as the example of DYNA Mill NC code shown later These machines are often programmed by downloading NC code from a computer, or manually programming the controller computer. Future trends involve,- adaptive feed rates to increase speeds as the metal removal rate varies- tool wear detection 14.2.3 Direct/Distributed Numerical Control (DNC) Uses a few methods,- the oldest methods used modems, and a mainframe which emulated a tape reader, to control the NC machine (no storage)- a more recent advance used a local computer which acts as a storage buffer. Programs are downloaded from the main DNC computer, and then the local controller feeds instructions to the hardwired NC machine, as if they have been read from tape.- the newer methods use a central computer which communicates with local CNC computers (also called Direct Numerical Control) DNC controllers came before CNC machines, but as computer technology impr oved it became practical to place a computer beside the NC machine, and DNC changed in form. Characteristics of modern DNC systems are,- uses a server (with large storage capacity) to store a large number of part programs。- the server will download part programs on demand to local machines- may have abilities to,- display and edit part programs- transmit operator instructions and other data needed at the machines- collect and process machine status information for management purposes Advantages are,- eliminates the need for NC tapes (the advantages are obvious)- design changes are immediate- NC programs may be edited quickly- can be used to support an FMS system- increase efficiency of individual machine tools- more shop up-time than with stand alone machines- simplifies implementation of group technology, computer aided process planning, and other CIM concepts-reduces peripheral costs with NC tapes A Brief History, Mid 60s- concept proved by Cincinnati Milacron and G.E.- telephone links used to send instructions from large computers to hard wired NC machines. Basically replaced a tape reader. 1970- several commercial DNC systems announced. Mid 70s- Aerospace companies used DNC because of the large number of distributed -machines in their facilities. Initial resistance to DNC technology was (previously) based on,- high cost of computer hardware- the number of machines which could be controlled by one computer was limited- computer sof tware was limited for maintenance, scheduling, control, and data collection- a backup computer was usually required- was hard to justify on the basis of downloading parts programs when downloading programs there are two popular opinions,- a program should only be downloaded in part, this accommodates easy engineering changes in a real-time environment.- many programs should be downloaded to the local controller to provide protection against system failure, and eliminating the cost of real-time response in the DNC centr al computer.14.3 EXAMPLES OF EQUIPMENT The number of NC machines available commercially will be well into the thousands. 14.3.1 EMCO PC Turn 50 This is a small desktop lathe capable of turning parts in metal. The basic physical specifications are, Cutting volume radial travel 48mm rad axial travel 228mmMax.holding volume radial 30-65mm axial 300mm 12mm by 12mm Max.tool size max 80mmm diaChuck 130-3000rpmSpindle 0.001mmResolution 0-750mm/minFeed =600N below 500mm/minFeed force 100/110/230VAC,0-6KVAPower 840 by 695 by 345 mm The basic sequence of operations for this machine are,1. Unpack components.2. Connect devices to power, air supply, and attach interface cables 3. Install RS-485 card in PC.4. Install software.5. Test basic system (Done initial setup here).6. Start and initialize lathe and PC with software.7. Setup tools for new job. Find zero positions/offsets, and enter values for turret.8. Load NC code.9. Simulate program.10.Load stock and close automatic chuck.11.Close door.12.Run program on Lathe.13.Open door and open chuck.14.If cutting a similar part go to step 8, if doing a new setup go to step 7. 14.3.2 Light Machines Corp. proLIGHT Mill This is a small desktop lathe capable of turning parts in metal. The basic physical specifications areCutting Volume Max. Holding VolumeMax. Tool SizeSpindle 200-5000rpmResolutionFeed 50ipm x,y and 40ipm zFeed ForcePowerDimensionsWeightController IBM compatible computerControl Interface IBM compatible computerProgramming G-Codes and Dos softwarSpindle 1 H.P. The basic sequence of operations for this machine are,1. Unpack components.2. Connect devices to power, air supply, and attach interface cables.3. Install software.4. Test basic system (Done initial setup here).5. Start and initialize mill and PC with software.6. Setup tool for new job. Find zero position/offset.7. Load NC code.8. Simulate program.9. Run pr ogram on Mill.10. If cutting a similar part go to step 7, if doing a new setup go to step 14.4 PRACTICE PROBLEMS14.5 TUTORIAL - EMCO MAIER PCTURN 50 LATHE (OLD) The lathe is shipped with software that is meant to emulate shop floor interfaces. We donnot have the standard keyboard, so we need to use special key stroke sequences on the PC keyboard. Procedure:1. Connect the air supply to the lathe and make sure that the regulator on the lathe is between 25 and 75 psi - 50 psi is good. Ensure that the lath is connected to the PC with the DNC cable. The computer card must also have a terminator on the second connector - this is an empty connector. Turn on the lathe, and the PC.2. Once the PC is booted, run the emco control software. The screen may come up with warnings. If these warnings dont disappear when you hit ESC call the instructor.3. First we must zero the lathe. To do this first hit F1 and then F7?-ZRN. A small label ZRN should appear near the bottom of the screen. Press 4 on the number pad of the keyboard - the lathe should move in the x dir ection. Next, press 8 on the keyboard, the lathe should move in the z direction. After all motion has stopped the lathe is calibrated, and it will be put in jog mode.4. You can move the lathe with the keys on the number pad as well as perform other function.4 - move carriage left6 - move carriage right2 - cross slide out8 - move cross slide in7 - turn spindle on6 - turn spindle off2 - turn on/off chip blower1 - turn tool turret+/- - increase/decrease feed5. You can now put the mill in MDI mode by pressing F1 then F6?-MDI. Push the door open and hold it for a second, it will then stay open. Clear the error on the screen with ESC and press the chuck should open and close. Mount a work piece and then close the door.6. Put the computer in program mode -14.6 TUTORIAL - PC TURN 50 LATHE DOCUMENTATION: (By Jonathan DeBoer) SETUP:The lathe is controlled by a computer through an RS485 port. RS485 is a serial data bus that can be chained from one device to another and must be terminated.The controlling computer must be running Windows 3.1 or 3.11 and must have the RS485 card installed. Windows 95 will not get along with the interface card, and the software refuses to use an RS232 port with an RS485 adapter. The machine should have as few peripherals as possible; if one device happens to use any of the IRQs/DMAs/IO ports as the RS485 card, there will be problems. So remove sound cards, extra interface cards, etc. The RS485 card has two DB9F connectors on the back, plug the cable from the lathe in one and a terminator in the other.Install WinNC (the control software) under Windows 3.1. There are two disks; the installer and a machine data disk.The lathe needs to be plugged in to the computer, to a power outlet (of course), and to an air supply at 50-75 psi (less than 50 and there isnt enough pressure to open the door). A pressure gauge is on the left side of the machine, all plugs/etc are on the right. POWER ON/OFF:To Turn On: Turn on the computer and machine. To turn on the machine, turn the key on the right side. On the computer, launch Windows if neccisary. Once windows is running, launch WinNC. Make sure NumLock is on befo re launching WinNC. WinNC will then establish communication with the machine.To Turn Off: To just shut off the lathe but not the computer, just turn the key on the lathe. An error will co me up in WinNC indicating it lo st RS485 communication. Not to worry; when the lathe is turned back on later, hit ESC and the error will go away.To turn off both, exit WinNC by hitting Alt-F4 and then exit Windows. Then Simply switch off both the machine and the computer. OPERATION:Some notes:The EMCO software is distinguished by having the most counter-intuitive, unnatu-ral, information-withholding, and ornery interface known to man. Most technical references available are in German。The software periodically pops up error messages for minor and major errors. Errors can be dismissed by pressing ESC. If they dont go away, there is a problem that needs to be looked into.At the bottom of the screen is a menu of options you can select with the F3-F7 keys. This is called the softkey list by the Emco documentation, and will henceforth be referred to as the menu.A note on coordinates: The X axis is into/out of the material. X = 0 should be the center of rotation. As long as X is a positive value, moving along X in the positive is moving the tool out of the material and away from center. Moving along X in the negative is moving into the material and toward center.The Z axis is along the length of the part (along the axis of rotation). Moving along Z in the negative direction is moving toward the spindle head (to the left, facing the machine). Moving along Z in the positive direction is moving away from the spindle head (to the right, facing the machine)。Modes:The software is ruled by mo des. What mode the software is in determines what it can do and what it displays. I f something doesnt work or doesnt look right, check what mode the software is in. Remember operational modes are set independently of display modes. The operational mode can be EDIT but programs cannot be edited until the view mode is set to PRGRM, and vice versa.Hit F1 to get a menu of operational modes: ZRN mode is used for zeroing the tool position. This should be done the first thing afterthe machine is turned on. JOG is used for manual control of the lathe. MDI is used for changing tools, opening chuck, etc. (actually, you can do all this with JOG) EDIT is used for editing, loading, and exporting programs. AUTO is used for running programs.Hit F12 to get display modes:Note: when you switch view modes, the menu changes.The default is ALARM mode, which displays operator messages and alarms. Hit F3 to display alarms, F5 to display operator messages.POS mode displays positions.Hit F3 to display the current absolute position, F4 for the current relative position, and F5 for a variety of details. PRGRM mode displays the program. Hit F3 to display the program code, hit F4 for a list of all the programs available. If the operational mode is EDIT, you can also edit the code when you hit F3 。 OFFSET is used for displaying and changing offset values. Hit F3 for wear adjustment and F4 for geometry. These are both parameters for tools.Data for up to 16 tools can be stored at once. Hit F5 for work shift. This is how the working reference point is set. See below. PARAM is used for changing setup parameters and viewing system information. Hit F3 for setup see below for details. Hit F4 for diagnostics on the RJ485 por t and the software version。 GRAPH is used to simulate output with a graphThe fact that all these modes must share the menu can cause confusion.Remember that if you should be seeing a menu and you arent, the menu you are looking for may be behind the one you are seeing. For example, when you switch to a display mode, you should see the menu f or that display mode. If you hit F1, that menu is covered up by the menu to select an operational mode. Once you select something from that menu, you will see the view modes menu again.Keyboard control:Note on keyboard control: Many of the keys outlined in the manual are for German keyboards only and are mapped differently on US keyboards. Use this as reference, NOT the manual:Alt-F4 - ExitESC - Dismiss error messageF1 - mode menuF3 thru F7 - select item from current menuF11 - scroll through menus when they are too wide to fit on the screen (like the MORE key on a Ti-85 calculator)F12 - function key menuCtrl- - open/close chuck (must not be in EDIT mode, door must be open)Ctrl- - open/close door (spindle must be off)Ctrl-1 - change tool (must not be in EDIT or ZRN mode, door must be closed)Ctrl-2 - Turn on/off blowerCtrl-6 - Turn off spindle (JOG mode)Ctrl-7 - Turn on spindle (JOG mode, door must be shut)arrows - move cursor in the editoron the numeric keypad:4 - move -Z in JOG mode, or zero Z axis in ZRF mode6 - move +Z in JOG mode, or zero Z axis in ZRF mode2 - move -X in JOG mode, or zero X axis in ZRF mode8 - move +X in JOG mode, or zero X axis in ZRF mode5 - zero both axis in ZRF mode From：Integration and Automation of Manufacturing Systemsby Hugh Jack14.数控机床计算机数控机床使用一台计算机引导一个可能需要手工完成的过程14.1机床坐标轴14.2 数字化控制使用数字数据驱动机器进行的加工过程如下-铣削-车削-钻削-磨削-喷丸加工- 折弯-火焰切割-自动化编制机-自动铆接-等数控系统的基本组成部分-程序-控制器单元-机床设备最适合于-频繁加工的小批量零件-复杂的部分几何体-工件上的紧公差部分-加工过程中操作量大的部分-大量的金属切削-工程设计可能变化时-价值昂贵不允许报废的零件开发数控程序的方法包括-手工零件编程-计算机辅助编程-计算机编程 手工和计算机辅助方法采用各种数控编程语言-自动编程工具-用于工具定位的自动化系统-桑斯川特内部转换处理语言-紧凑型 2- APT改编语言- APT 的扩展子集- UNIAPT这些语言是通过一部分编程人员定义切削刀具的动作来使用的这些语言可以进行预处理，然后为一系列不同的控制类型所使用，例如-穿孔纸带-计算机数字控制（CNC）-直接数字控制（DNC） 自动化方法与CAD程序中创建的几何体一起工作14.2.1数控条带数控程序在计算机上进行预处理，并在纸条或胶带上打孔简单的数控机床可以使用条带带阅读器来指挥机器相关问题-数控条带所必需的存储，传输，手动装载-必须为每个新零件重读条带-磁带往往磨损，变脏，从而导致误读-阅读器很慢，并且可能在复杂零件上产生滞留标记-阅读器里的机械零件降低了可靠性-测试必须在数控机床上完成-没有程序编辑能力（增加了所需的时间）条带的结束是两种发展相互竞争的结果-分布式数控使用远程计算机来代替条带阅读器，但这些在大多数情况下被计算机数控所取代-计算机数控还允许在本地计算机上使用以克服条带和远程计算机的问题。虽然一段时间内计算机数控被用来加强条带性能，但计算机数控最终被允许使用其他存储介质，并且目前不需要程序传输介质14.2.2计算机数字控制一个电脑控制器是用来直接驱动数控机床的特点是-控制一台机器-位于非常接近机床的地方-允许没有预处理的数控代码进行数控程序存储/输入/检索数控的优势， - 程序只输入到内存中一次，所以它更可靠 - 该程序可以在机器测试和修改 - 在本地计算机上增加了控制选项增强了灵活性- 易于集成到柔性制造系统 相关背景-使用DNC网络处理与数控条带有关的问题-使用DNC系统的通讯问题变得显著，并且本地计算机被添做能读取条带一次并可以让数控机床无限回放的的条带阅读器-数控控制器开始使用其他像磁带，软盘之类的存储器-数控现在提供的功能如下 -本地程序 -接口通信 -硬盘存储 -程序仿真 -等旁白：除了一台远程计算机用来控制许多机器之外，直接数控与计算机数控很相似。这给出了更强大的计算机功能的优势。由于电脑成本下降抵消了任何优势，这种方法不再流行。有些公司使用专用的数控语言，例如最近展示的德纳铣削数控代码这些机器经常冲电脑上下载数控代码编程，或手工对控制器电脑进行编程。 未来走向涉及- 根据不同的金属切削速率自动调整进给速度以提高加工速度- 刀具磨损检测14.2.3直接/分布式数控（DNC） 使用了以下几种方法-最古老的是使用调制解调器和一台仿效条带阅读器的主机来控制数控机床（不能存储）-一个新近的方法是使用一台用作存储缓冲的本地电脑。从主计算机数控主机上下载程序，然后本地控制器像从纸带上读取程序一样把程序提供给数控机床-较新的方法是使用一台能与本地数控电脑交互的核心电脑（也称作直接数字控制） DNC控制器产生于CNC机床之前，但由于计算机技术的发展DNC变的比在数控机床旁放置计算机实用并且DNC在形式上产生了变革现代的DNC系统的特点是-使用服务器（有很大的存储容量）来存储大量的零件程序 -服务器将根据需要把零件程序下载到本地机床上 有能力- 显示和编辑零件程序- 传送机床上需要的操作指令和其他数据- 收集和处理用来操纵机床的状态信息 优点- 不再需要数控条带（优点是显而易见的）- 即时的设计变更- 数控程序编辑快速- 可以用来支持FMS系统- 提高了单个机床的效率- 比单个机床有更多的工厂运行时间- 简化成组技术，计算机辅助工艺规划和其他计算机集成制造内容的实施- 减少使用数控纸带的额外花费 历史概述,60年代中期- 辛辛那提米拉克龙概念和GE证明- 电话链接用来从大型计算机向硬件连接的数控机床发送指令，这从根本上取代了读带器 1970- 几个商业的DNC系统公布 70年代中期- 航天公司因为他们工厂里有大量的分布式机床而使用DNC DNC技术最初的阻碍是（以前）基于-计算机硬件的高额成本-一台计算机能控制的机器数量是有限的- 计算机软件因为维护调度控制和数据收集而受限制- 通常需要一台备份计算机- 在下载部分程序的基础上很难调整 下载程序时，有两种流行的观点- 一个程序只能被部分下载, 这在现实环境中很容易改变原