数控技术双语4.ppt

1、1,Electromechanical Engineering CollegeHenan University of Science and Technology,NUMERICAL CONTROL TECHNOLOGY,韩建海,2,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction 4.2、Hardware Architecture of CNC Unit4.3、CNC System Software4.4、PLC functions in CNC Unit4.5、Human-M

2、achine Interface and Operation Sequence of CNC System4.6、Open Architecture System for CNC Unit,3,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,Today,computer numerical control(CNC)machines are found almost everywhere,from small job shops in rural communities to Fortune 500 compan

3、ies in large urban areas.Truly,there is hardly a facet of manufacturing that is not in some way touched by what these innovative machine can do.Everyone involved in the manufacturing environment should be well aware of what is possible with these sophisticated tools.,4,数控技术,Chapter 4 CNC Unit,Chapte

4、r 4 COMPUTER NUMERICAL CONTROL UNIT,In this chapter,we will explore the basics of the core of CNC machine tool CNC unit,showing you much of what is involved with its functions,working principles,hardware configuration and software structure.With so many types of CNC machine tools and CNC units in ex

5、istence,it is next to impossible for this chapter to be extremely specific about any one particular type.The key concepts allow us to view the main features of CNC unit in more general terms,stressing why things are handled the way they are even more than the specific techniques used with any one pa

6、rticular CNC machine tool.With this broad background,you should be easily zero in on any kind of CNC machine tool you will be working with.,5,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Machine controls are divided into two types:numerical control(NC)and comput

7、er numerical control(CNC).NC controls have to read the program each time a part is run;they have no means of editing existing programs.CNC controls can store and allow editing of loaded programs.All machines built today are CNC machines.CNC unit is the heart of CNC machine.Nevertheless,in order to a

8、id to understand the working principles of CNC unit,it is necessary that the principles of NC system be introduced firstly.,6,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,The NC machine can be divided into three basic areas.The first area is the control unit,whi

9、ch processes the command from the input media.The second area is the drive mechanisms,and the last area is the machine itself.,4.1.1 NC system,7,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,The most basic function of any NC machine is automatic,precise,and consi

10、stent motion control.All forms of NC equipment have two or more directions of motion,called axes.These axes can be precisely and automatically positioned along their lengths of travel.The two most common axis types are linear(driven along a straight path)and rotary(driven along a circular path).,4.1

11、.1 NC system,8,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Instead of causing motion by manually turning cranks and handwheels as is required on conventional machine tools,NC machines allow motions to be actuated by servomotors under control of the NC and guide

12、d by the part program.Generally speaking,the motion type(rapid,linear,and circular),the axes to move,the amount of motion and the motion rate(feed rate)are programmable with almost all NC machine tools.Figure 4.1 shows the makeup of a linear axis of an NC machine.,4.1.1 NC system,9,数控技术,Chapter 4 CN

13、C Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,An NC command executed within the control(commonly through a program)tells the drive motor to rotate a precise amount of angle.The rotation of the drive motor in turn rotates the ballscrew.And the ballscrew drives the linear axis.A fe

14、edback device at the opposite end of the ballscrew allows the control to confirm that the commanded number of rotations has taken place.,4.1.1 NC system,10,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,All NC machine tools need numerical data for controlling the

15、relative motion between cutting tool and piece part,the component dimensions normally emanating directly from engineering drawings the geometric data.Other digitized numerical data define feed rates,spindle speeds,tool identification numbers,and miscellaneous functions to perform such operations as

16、tool or work changing,or coolant control the technological data.,4.1.1 NC system,11,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,The combination of all this numerical information in a sequence understood by the machine tools controller is called a part program,a

17、nd the process of creating the data in a correctly structured format is called programming.,4.1.1 NC system,12,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Numerical controls use standard microelectronic modules that have been developed for computer hardware.Exc

18、ept for special modules needed in servocontrol circuits,no individual modules are necessary,in contrast to traditional controls,which employ only components tailored to suit one specific control function.In modern NC controllers extensive control and calculation tasks are performed by one or more in

19、tegral microprocessors.These are termed computer numerical control system(CNCs).,4.1.1 NC system,13,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Control systems based on industrial PC(abbreviation for personal computer)are increasingly used in automation technol

20、ogy.Machine controls have changed greatly with the“age of the computer”.Controls today are“soft-wired”,which allows greater flexibility in changing and upgrading the computer control.,4.1.2 CNC system and function of CNC unit,14,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、I

21、ntroduction,In fact,many of machines operating characteristics can be changed by the operator,so that the machine operates the way he/she wants it to.Parameter tables in CNC machines today allow each machine to be personalized to the needs of the job to be run.The modern CNC machine tool is software

22、 driven.Simply speaking,computer controls are programmed instead of hard-wired.,4.1.2 CNC system and function of CNC unit,15,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Definition:According to Electronic Industrial Association(EIA),CNC system is a special compu

23、ter system that is equipped with certain interface circuits and servo drivers,and can do part or all the works an NC system do by running the software stored in its memories.,4.1.2 CNC system and function of CNC unit,16,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introducti

24、on,CNCs have expandable memories that can store large number of programs,plus subroutines and correction data.Sophisticated graphic displays and dynamic simulation have also now become available as a result of the extensive memory capacity being built into current CNCs.,4.1.2 CNC system and function

25、 of CNC unit,17,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Within only few years,the capability and efficiency of machine controllers has increased to such an extent that the name“numerical control”is no longer appropriate;“computer numerical control”is more a

26、ccurately descriptive.,4.1.2 CNC system and function of CNC unit,18,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,Generally,CNCs comprises CNC unit,feed motion servo subsystem,spindle servo subsystem and some auxiliary control cells,as show in Figure 4.2,CNC unit

27、 is the core of the whole CNC system.It is composed of hardware and software.The hardware comprising a CNC unit is made up of microprocessors,electronic memory modules,I/O interfaces,and position control modules,etc.,4.1.2 CNC system and function of CNC unit,19,数控技术,Chapter 4 CNC Unit,Chapter 4 COMP

28、UTER NUMERICAL CONTROL UNIT,4.1.2 CNC system and function of CNC unit,20,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,CNC software controls all functions of the machine and its efficiency of operation,and manages all local programming at the machine tool and gra

29、phic simulation of the cutting process if available.,4.1.2 CNC system and function of CNC unit,21,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,The hardware and the software work together to do all function of CNC unit,which an ordinary NC system can never do,suc

30、h as graphic display HMI(Human-Machine Interface),system diagnosis,implementing of various complex toolpath controlling and compensation algorithms,intelligent controlling,online programming,and Web communications,etc.,4.1.2 CNC system and function of CNC unit,22,数控技术,Chapter 4 CNC Unit,Chapter 4 CO

31、MPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,4.1.2 CNC system and function of CNC unit,Operation panel,PLC,Spindle serve cell,Spindle driver,MachineTool,I/O Devices,CNC Control Unit,Feed motion servo cells,Detect device,Feed drivers,Keyboard,Machine tool I/O circuits and devices,CNC system,23,数控技术

32、,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,(1)Controlling function(the number of control axes and synchronously control axes),4.1.2 CNC system and function of CNC unit,Controlling function indicates the maximum axis-number the CNC unit can control and the number o

33、f axes the CNC unit can control synchronously.It is also the main features of CNC machine.Axes to be controlled by CNC unit have linear axes and rotate axes,basic axes and auxiliary axes.Generally,CNC machine needs only 2 axes to be controlled synchronously.In case of double tool-slide,four axes are needed.,24,数控技术,Chapter 4 CNC Unit,Chapter 4 COMPUTER NUMERICAL CONTROL UNIT,4.1、Introduction,(1)Co