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1、.Chapter 2 NC PART PROGRAMMING2.1、Introduction to NC part programming2.2、The codes used in CNC2.3、Manual part programming2.4、Automatic programming第1页/共106页.Chapter 2 NC PART PROGRAMMING2.1、Introduction to NC part programming The program of instructions is the detailed step-by-step commands that dire
2、ct the actions of the processing equipment.In machine tool applications,the program of instructions is called a part program,and the person who prepares the program is called a part programmer.Numerical control(NC)is a form of automatically operating a machine tool based on coded alphanumeric data.A
3、 complete set of coded instructions for executing an operation is called a program.The program is translated into corresponding electrical signals for input to servo motors that run the machine.第2页/共106页.Chapter 2 NC PART PROGRAMMING1、Introduction to NC part programming we call the whole process fro
4、m part graphics to finishing control medium the programming of numerical control manufacturing,or call it NC programming.When using numerical control machine tool to manufacture parts,the programming is very important.The program is not only correct and fast but also effective and economic第3页/共106页.
5、Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming The program can be inputted into CNC system and the CNC system controls CNC machine tools to manufacture automatically.Generally speaking,the main steps of NC programming are analyzing part graphics,determinin
6、g the manufacturing technological process,calculating numerical value,programming,verifying the program and inputting the program into CNC system.Figure2.1 illustrates the programming steps.第4页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming Before NC
7、 programming,the programmer should understand the numerical control machine specifications,characteristics,the functions and programming instructions format of the CNC system,etc.When programming,he should analyze the parts technical requirements,geometrical shape,dimensions and technological requir
8、ements.Then he can determine the manufacturing method and calculate numerical value,get cutter position.According to part dimension,cutter position value,cutting parameters(spindle speed,feed-rate,cutting depth)and auxiliary functions(ATC,CW,CCW,coolant on and off),the programmer can program.第5页/共10
9、6页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(1)AnalyzingpartgraphicsanddeterminingthemanufacturingtechnologicalprocessThisstepincludesanalyzingthepartgraphics,understandingthemachiningcontentsandrequirements.Thendeterminingtechnologicalprocesses,machi
10、ningplans,machiningsequence,machiningroutes,fixingmethods.Cuttingparametersandselectingcuttingtools,etc.Besidesthese,thenumericalcontrolmachinecodesshouldbeunderstoodclearlyandthenumericalcontrolmachinefunctionsshouldbeexploitedfully.第6页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and step
11、s of numerical control programming Analyzing part Analyzing part graphicsgraphicsTechnological Technological processprocessSelecting programing origin and Selecting programing origin and coordinate systemcoordinate system Calculating Calculating numerical valuenumerical valueWriting&verifying part W
12、riting&verifying part programsprograms NC machine NC machine tooltoolFigure 2.1 The steps of NC programming第7页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(2)CorrectlyselectingprogramoriginandcoordinatesystemInnumericalcontrolmachinetoolsmanufactur
13、ing,correctlyselectingprogramoriginandcoordinatesystemisveryimportant.OnNCprogramming,theprogramcoordinatesystemisthestandardcoordinatesystemascertainedontheworkpiece.第8页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(3)CalculatingnumericalvaluesAfte
14、rfinishingthetechnologicalprocess,thenextstepistogetthetoolpathaccordingtopartgeometricdimensionandthemethodofcutterradiuscompensation,sowewillobtainthecutterposition.第9页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(4)WritingpartprogramsAfterdeterm
15、iningmachiningroute,technologicalprocessandthecoordinatevalueoftoolpath,step-by-step,theprogrammercanwritetheprograminaccordancewiththespecifiedfunctioncodesandprogramformatofCNCsystem.第10页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(5)Fabrication
16、controlmediumTheprogramiscodedonasuitablemediumforsubmissiontothemachinecontrolunit.Formanyyears,thecommonmediumwas1-inchwidepunchedtape,usingastandardformatthatcouldbeinterpretedbythemachinecontrolunit.Today,punchedtapehaslargelybeenreplacedbynewerstoragetechnologiesinmodernshops.Thesetechnologiesi
17、ncludemagnetictape,diskette,andelectronictransferofpartprogramsformacomputer.第11页/共106页.Chapter 2 NC PART PROGRAMMING2.1.1 The contents and steps of numerical control programming(6)VerifyingpartprogramsBeforetheprogramisusedinrealproduction,wemustchecktheprogram.wedetecttoolpatherrorsthatcouldruinth
18、epart,damagethefixtures,breakthecuttingtoolorcrashthemachine,etc.Insomecases,wetesttheprogramthroughmanufacturingapartonamachine.Onthebasisofdetectingresult,theprogramisneededtobemodifiedandtobeadjusted,untiltheprogramsatisfiesthemachiningrequirementscompletely.第12页/共106页.Chapter 2 NC PART PROGRAMMI
19、NG2.1.1 The contents and steps of numerical control programmingThestepsabovementionedareprogrammedmanually.Thisprogrammingmethodiscalledmanualpartprogramming.Andwealsoknowthataprogrammernotonlymusthavetheknowledgeofthestructureofmachinetools,thefunctionsandstandardsofCNCsystem,butalsohavetheknowledg
20、eoftechnologicalprocess,suchasfixtures,cuttingtoolsandcuttingparameters,etc.第13页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods of NC ProgrammingPartprogrammingcanbeaccomplishedusingavarietyofproceduresrangingfrommanualmethodtohighlyautomatedmethod.(1).Manualpartprogramming(2).Automaticprogram
21、ming第14页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods of NC Programming(1).Manualpartprogramming The programming is called manual part programming which whole part programming is completed manually(including calculating numerical value on a computer).In many mechanical manufacturing trades,t
22、here are a large number of uncomplicated parts that are constituted only by the simple geometric elements of straight lines and circles.the numerical values of the parts are calculated simply.第15页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods of NC Programming(1).Manualpartprogramming The blo
23、cks of a program arent lot.And checking the program is easy.These part programs can be completed manually.So manual programming is still a very common programming method at home and abroad.But manual programming has difficulty or impossibility go program complicated parts that have non-circular curv
24、es and surfaces.So we must use the automatic part programming to program.第16页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods of NC Programming(1).Automaticprogramming Automatic programming is also called computer-aided programming.Most or all of the programming is completed by a computer,such
25、as calculating numerical values,writing programs,fabricating the control medium,etc.Automatic programming lightens programmer intensity of labor,shortens the programming time and improves the programming quality.第17页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods of NC Programming(1).Automatic
26、programming At the same time,it solves the complicated part programming which is impossible to program by manual programming.The more parts are complicated shape and technological process,the more superiority of automatic programming clear is.第18页/共106页.Chapter 2 NC PART PROGRAMMING2.1.2 The Methods
27、 of NC Programming(1).Automaticprogramming There are many methods of automatic part programming.According to the differences of input programming message and handling styles by a computer,they are divided into automatically programmed tool(APT)based on automatic programming language and part program
28、ming using CAD/CAM based on interactive graphics system.A CAD/CAM system is a computer interactive graphics system equipped with software to accomplish certain tasks in design and manufacturing.第19页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofN
29、CPartProgramming The location of a CNC machine tools at any time is controlled by a system of XYZ coordinates called Cartesian coordinates.This system is composed of three directional lines,called axes,mutually intersecting at an angle of 900.The point of intersection is known as the origin.(1).NCCo
30、ordinateSystems第20页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (1).NCCoordinateSystems Primary machine axes of movement should follow the right-hand rule.See left figure.Spindle movement is primarily along the Z axis.movement
31、 into the workpiece is along the Z axis and movement away from is along the+Z axis.第21页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (1).NCCoordinateSystems In a majority of milling machines,motion along the X axis is the longe
32、st travel perpendicular to Z.the X axis is parallel to the work holding and is in the horizontal plane.The+X axis moves to the right along a plane of the work as the operator looks at that plane.spindleworktable第22页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.The
33、GeometricBasisofNCPartProgramming (1).NCCoordinateSystems With regard to milling machines,motion along the Y axis is the shortest travel perpendicular to Z,the Y axis is in the same plane as the X axis.Looking at the plane,the operator will note that the Y is perpendicular to the X axis.spindleworkt
34、able第23页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (1).NCCoordinateSystems Most CNC milling machines can perform simultaneous motions along the X,Y and Z axes and are called three-axis machines.See left figure.第24页/共106页.Cha
35、pter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (1).NCCoordinateSystems More complex CNC machines have the capability of executing additional rotary motions as follows:vRotation about an axis parallel to the X axis or A-axis rotationvRotat
36、ion about an axis parallel to the Y axis or B-axis rotation.vRotation about an axis parallel to the Z axis or C-axis rotation第25页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (1).NCCoordinateSystems Rotary motion directions als
37、o follow the right-hand rule.See right figure.、第26页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPartProgramming (2).Programzeropoint第27页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.1.TheGeometricBasisofNCPar
38、tProgramming (3).Typesoftoolpositioningmodes第28页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.2.TheTechnologicalBasisofNCProgramming (1).Determiningthepartmachiningroutesrationally第29页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programming2.1.3.2.
39、TheTechnologicalBasisofNCProgramming (2).SelectingtoolsettingpointandtoolchangingpointrationallyvThe setting point makes operating easily and programming simply;vThe point is easy to find;vThe caused machining error is small.第30页/共106页.Chapter 2 NC PART PROGRAMMING2.1.3 The Basis of NC Part Programm
40、ing2.1.3.2.TheTechnologicalBasisofNCProgramming(2).Selectingtoolsettingpointandtoolchangingpointrationally boring boring tooltool drill drill end mill end mill face tool face tool figure toolfigure toolball nose ball nose endmillendmillTurning toolTurning tool第31页/共106页.Chapter 2 NC PART PROGRAMMING
41、2.1.3 The Basis of NC Part Programming2.1.3.2.TheTechnologicalBasisofNCProgramming (3).Rationallyselectingthemethodsoffixing,cuttingtoolsandcuttingparametersvSelecting standard and common fixtures as far as possible,avoiding selecting special fixtures;vFixing and removing parts quickly,conveniently
42、and rationally;vThe part surface to be machined should be exposed to outside.Dont let the fixture affect the rapid motion and machining of a tool.第32页/共106页.Chapter 2 NC PART PROGRAMMING2.2、THE CODES USED IN CNC There are many codes included in a program.Preparatory functions are G codes and auxilia
43、ry functions are M codes.They are the base of CNC programs.ISO has worked out the standards of G codes and M codes.Because new CNC systems and machines have been emerging,a lot of functions in many systems surpass ISO standards.Their codes are abundant and their formats are flexible.They arent restr
44、ained by ISO standards.第33页/共106页.Chapter 2 NC PART PROGRAMMING2.2、THE CODES USED IN CNC In addition,even if the same function,its code and format have a lot of differences among systems made in different companies.And codes and formats also have differences between new and old systems made in the s
45、ame company.But the preparatory functions codes and auxiliary functions codes in most of CNC systems are up to or similar to the ISO standards.Before introducing the G codes and M codes,we must understand programming langue formats first.第34页/共106页.Chapter 2 NC PART PROGRAMMING2.2.1 Programming Lang
46、uage Format AprogramformatisasystemofarranginginformationsothatitissuitableforinputtoACNCcontroller.Severaldifferenttypesofformatsexist.Theformattobeusedinthistextisknownasthewordaddress.(1)AddressesAnaddressisaletterthatdescribesthemeaningofthenumericalvaluefollowingtheaddress.第35页/共106页.Chapter 2
47、NC PART PROGRAMMING2.2.1 Programming Language Format (2)WordsWordsareusedtodescribesuchimportantinformation.asmachinemotionanddimensionsintheblock.Programwordsarecomposedoftwomainparts:anaddressfollowedbyanumber.TheFigure2.9illustratestheaddress,numberandwords.G17 Address NumberY-35.68 Address Numbe
48、rWords 第36页/共106页.Chapter 2 NC PART PROGRAMMING2.2.1 Programming Language Format (3)BlocksAblockisacompletelineofinformationtotheCNCmachine.Itiscomposedofonewordoranarrangementofwords.Blocksmayvaryinlength.Thus,theprogrammerneedsthosewordsinablocktoexecuteaparticularmachiningfunction.“N10 G01X-63.75
49、Y70.28F100.S1000M03;”.Each block is separatedfromthenextbyanendof-block(;)code.第37页/共106页.Chapter 2 NC PART PROGRAMMING2.2.1 Programming Language Format (3)BlocksTheend-of-blockcharacterisautomaticallygeneratedwhentheprogrammerpressesreturnkeyatthecomputer.Thesameholdstruewhentheend-of-blockkeyispre
50、ssedatthemachinepanelboardduringmanualdateentry.Thus,thischaracterwillnotappearintheregularprogramlistingsinthistext.第38页/共106页.Chapter 2 NC PART PROGRAMMING2.2.1 Programming Language Format (4)ProgramsAprogramisasequenceofblocksthatdescribeindetailthemotionsaCNCmachineistoexecuteinordertomanufactur