PROE-NC-高速加工概述課件

1、Utilizing Pro/NC High Speed Machining StrategiesHigh Speed MachiningOverviewWhy High Speed Machining ?Components of High Speed MachiningMisconceptions about High Speed MachiningWhat is High Speed Machining? The High Speed MachiningProcessHow to Start?Why High Speed Machining?Reduces machining timeSh

2、ortens lead timeReduces, even eliminates, post-machining processesShortens preparation timeEnhances the quality of the finished partHSM: Machining TimeReduces machining timeFor various materialGraphiteAluminumCast ironMild steelPre-hardened steelTough-to-cut material Hardened steel, Titanium, Incone

3、l, etc.Greater rate of material removalHigher speed advantages offset disadvantages of greater number of slicesWhy High Speed Machining?Reduces machining timeShortens lead timeReduces, even eliminates, post-machining processesShortens preparation timeEnhances the quality of the finished partHSM: Lea

4、d TimeShortens lead timeEven for hardened steelConventional ProcessPolishingEDMBurningHeat Treat Roughing Making Electrodes High Speed Machining ProcessRough to finish operations in one machining processHigh Speed MachiningWhy High Speed Machining?Reduces machining timeShortens lead timeReduces, eve

5、n eliminates, post-machining processesShortens preparation timeEnhances the quality of the finished partHSM: Post-Machining ProcessesReduces, even eliminates, post-machining processesHigh quality machined surfacesSuperb machining accuracyMirror quality finishNo need for bench work and polishingLess

6、time spent on adjustments during insert or mold base assemblyWhy High Speed Machining?Reduces machining timeShortens lead timeReduces, even eliminates, post-machining processesShortens preparation timeEnhances the quality of the finished partHSM: Preparation TimeShortens preparation timeReduces the

7、requirement for different toolsConventional machining requires 3 tools to make an entry hole and pocketHSM can make use of one tool onlyCorners of differing radii can be machined with one toolConventional Machining:High Speed Machining:Spot DrillDrillMillBall Nose EndmillHelical Cutting of the holeW

8、hy High Speed Machining?Reduces machining timeShortens lead timeReduces, even eliminates, post-machining processesShortens preparation timeEnhances the quality of the finished partHSM: Part QualityEnhances the quality of the finished partLess tool deflectionLess warpage on thin wallsEliminates bench

9、 workMaintains accuracy of small detailed geometry Eliminates blending of electrode marginsMaintains accuracy of radiiMore consistent geometryLess tool wearComponents of High Speed CuttingComponents of High Speed CuttingMachine Tool & ControllerComponents of High Speed CuttingSpindles, Holders and C

10、utting ToolsControlled temperatureHigh precision bearingsGood concentricityQuick acceleration and decelerationComponents of High Speed CuttingMachine StructureWithstand heavy loadsHigh responsiveness & high feed ratesThe bed, column & table ensure a high structural rigidityComponents of High Speed C

11、uttingLinear Guide Ways Linear MotorsNo ballscrewsMinimumbacklashHigh responsivenessComponents of High Speed CuttingController SystemGood control software for data handlingGeometric errors arising from the servo lag can be overcomeServo LagAxis Reversal ErrorsErrors when movement direction is revers

12、edFast Data ProcessingAt high feed, tool can finish the move before the next move is ready, or vice-versaTool dwells, undershoots or overshootsLook AheadAnticipate tool path changes, & vary the feed accordinglyGouge AvoidanceSmoother Acceleration & DecelerationComponents of High Speed CuttingSpeedin

13、g in the cornersHow Fast ?Arc the CornersBlindly adding arcs on toolpath corners is NOT High Speed MachiningFor this example, a distance between the path of 1 mm became 1.5 mm at the corners50% more loadConsidering the heavier material at the corner, and the load shoots up to more than 100%More seve

14、re conditions for sharper cornersSpline / NURBS dataNURBS or Spline interpolation is NOT High Speed MachiningStraight lines can be represented in NURBSNURBS is not exact data from the CAD systemEven if CAD data was in NURBSCannot offset easily NURBS curve or surfaceToolpath seldom follows UV linesNU

15、RBS are controller requirementsUse if the controller behave better with NURBS, rather than linear, circular or helical interpolationWhat is High Speed Machining?Stable Cutting ConditionsMaintain low temperatures at the tool cutting edgeShallow cuts, both in depth and radial directionSmall cutting lo

16、adAdditional advantages for low rigidity workpiecesMaintain constant cutting loadConsistent tool deflectionLess vibration and chatterLess tool wearEffectively remove the cut chipsThru-spindle coolant or airThru-tool coolant or air (deep cavity)Axial DepthAxial DepthRadial DepthRadial DepthStable Cut

17、ting ConditionsMaintain low temperatures at the tool cutting edgeShallow cuts, both in depth and radial directionSmall cutting loadAdditional advantages for low rigidity workpiecesStable Cutting ConditionsTool BreaksTool BurnsIdealLoadConditionMaintain constant cutting loadConsistent tool deflection

18、Less vibration and chatterLess tool wearMaximizedTool LifeStable Cutting ConditionsEffectively remove the cut chipsThru-spindle coolant or airThru-tool coolant or air (deep cavity)High Speed MachiningTOOLSHigh stressHigh Speed MachiningTOOLSMore Constant Material Removal ProcessHigh Speed RoughingCo

19、nstant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of sudden tool direction changes Reduction of repositioning movesBalancing all these sometimes-contradictory requirementsRoughing: Cutting ConditionConstant Cutting ConditionClimb CuttingLe

20、ss heat is generatedSmaller forces on toolWork hardening is minimized, even eliminatedBetter surface finishHigh Speed RoughingConstant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of sudden tool direction changes Reduction of repositioning m

21、ovesConstant Chip LoadRate of material removal as constant as possibleMaintains constant chip sizeBetter heat transferBoth tool and workpiece stay coolNo need to manipulate feedrates and spindle speedsLonger tool lifeBetter part qualityNever bury in the materialRoughing: Chip LoadHigh Speed Roughing

22、Constant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of sudden tool direction changes Reduction of repositioning movesRoughing: Approaching the CutsApproach from outside the material, when possibleFor regions with open wallsReal-time analys

23、is of the cut materialClosed regionsAll regions with no open wallsHelical plunging approachOpens up an approach locationHigh Speed RoughingConstant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of sudden tool direction changes Reduction of re

24、positioning movesRoughing: Tool EngagementContinuous tool engagementWhenever possibleWithout breaking prior rulesClimb machiningConstant loadDo not bury the toolHigh Speed RoughingConstant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of sudd

25、en tool direction changes Reduction of repositioning movesRoughing: Minimize Sudden MovesMinimization of sudden tool direction changesRetrofitted machines will always overshoot or undershootHSM machines have no overshoot/undershoot problemsAutomatically slow down in cornersLonger-than-planned cycle

26、timeChip size at the corner goes down Volume of chip material too small to carry heat Tool heats up Premature failuresLook Ahead Functionality Alone is Not Enough!High Speed RoughingConstant cutting conditionConstant chip loadApproach from outside materialContinuous tool engagementMinimization of su

27、dden tool direction changes Reduction of repositioning movesRoughing: Minimize Repositioning MovesReduction of repositioning movesPrevent retract movesMinimize non-cutting time Without breaking prior rulesClimb machiningConstant loadDo not bury the toolHSM rapid at rates around 50 000 MMPM.Help the

28、machine reach maximum speed on repositioning movesReduce the need for great accelerations / decelerationsSmooth repositioning movesRoughing: Closed Areas BehaviorHelical spline approach to open up the materialTangent to both the approach move and the cutOnce open, the helical location is now an open

29、 wallContinuous spiral cut, until a wall is reachedConstant loadConstant cutting conditionContinuous cuttingRemainder material is treated as open areasOpening 5Material boundaryOn approach, tool load goes up greatlyOn outside corners, tool load goes downOn inside corners, tool load goes up greatlyTr

30、aditional Cutting ApproachTool load changes are quite severeGuard against critical tool conditions by artificially lowering cutting expectationsExampleApproach: load up rapidly from 0 to 2x cutting load Outside corners: load down to 0 tool moves outside material when turning the cornerInside corners

31、: load up from cutting load to 2x cutting load tool catches material on the front wall before turning the cornerTool Load ProfileTool Load ProfileBalanced-load Cutting ApproachEliminates load spikes Allows for a more aggressive roughing strategyHigher performance roughing approachAnalyzing the mater

32、ial Building tool path based on material rather than resultant geometryRunning machines at their optimal speed Additional Roughing ScansMaintain CUT_TYPE (Climb/Conventional)Ideal for pockets with aspect ratio 5Climb boundaries, maintain cut typeControl of wall profile feeds and speeds Maintain CUT_

33、DIRECTION Ideal for pockets with aspect ratio 5Climb material, maintain cut direction Control of wall profile feeds and speeds Follow Hard WallsIdeal for core parts with minimal concave corners (bad for concave corners)Offset only of hardwalls“S”-connection moves for closed contour transitionsHigh S

34、peed Roughing3421234Maintain Cut Type ScanVolume NC sequencesParameters:ROUGH_OPTION = ROUGH_ONLYSCAN_TYPE = MAINTAIN_CUT_TYPECUT_TYPE = CLIMBSTEP_DEPTHSTEP_OVER Must be 1/2 of TOOL_DIAMETERCLEAR_DISTOptional controls:RAMP_ANGLE HELICAL_DIAMETERCORNER_ROUND_RADIUSTRIM_TO_WPMaintain Cut Direction Sca

35、nVolume NC sequencesParameters:ROUGH_OPTION = ROUGH_ONLYSCAN_TYPE = MAINTAIN_CUT_DIRECTIONCUT_TYPE = CLIMBSTEP_DEPTHSTEP_OVER Must be 1/2 of TOOL_DIAMETERCLEAR_DISTOptional controls:RAMP_ANGLE HELICAL_DIAMETERCORNER_ROUND_RADIUSTRIM_TO_WPFollow Hardwalls ScanVolume NC sequencesParameters:ROUGH_OPTIO

36、N = ROUGH_ONLYSCAN_TYPE = FOLLOW_HARDWALLSCUT_TYPE = CLIMBSTEP_DEPTHSTEP_OVER Must be 1/2 of TOOL_DIAMETERCLEAR_DISTOptional controls:RAMP_ANGLE HELICAL_DIAMETERCORNER_ROUND_RADIUSTRIM_TO_WPHigh Speed Re-roughingNC sequences: Local / Prev SequenceParameters:SCAN_TYPE = CONST_LOADCUT_TYPE = CLIMBSTEP

37、_DEPTHSTEP_OVER Must be 1/2 of TOOL_DIAMETERCLEAR_DISTOptional controls:RAMP_ANGLE HELICAL_DIAMETERCORNER_ROUND_RADIUSTRIM_TO_WPHigh Speed FinishingTool contact point determines finishing strategyClassification of sections of surfaces Shallow Steep FlatFor a given RPM and feed, higher surface footag

38、e on steep wallsMinimize sharp movesMinimum arc value ( 1.5 x tool radius)Leave sharp concave corners for post-finishing operationsCorner clean-upStay in cut when possibleSlope AngleHigh Speed FinishingTrue Scallop Height2D Scallop Height Computation3D Scallop Height ComputationClassify surfaces for

39、 finishing based on slopeCreate 2 Mill Surfaces (Steep and Shallow)Mill Surface Type: Advanced / SlopedDirection PlaneSlope AngleSelect whether to keep the shallow or steep portionUse the mill surface for machining strategyFlat horizontal planesSequence type = VolumeROUGH_OPTION = FACES_ONLYFinishin

40、g: Surface ClassificationShallowShallowSteepAngle = 10 - 30Finishing: Steep AreasContinuous profile finishing Maintain the tool in cut transitions between slices or cuts with 2D or a 3D “S” move for closed connections Smooth and continuous finishing toolpathHigh Speed friendly approaches and exits T

41、angent SplineHelical or Tangent arcAny approach/exit that yields little direction changeSteep Areas Finishing: SettingsVolume NC sequencesParameters:ROUGH_OPTION = PROFILE_ONLYSCAN_TYPE = CONST_LOADSTEP_DEPTHCLEAR_DISTOptional controls:NUM_PROF_PASSESPROF_INCREMENTCORNER_ROUND_RADIUSHigh Speed Machi

42、ning: Corner ConditionFor both roughing and profile finishingGuards against undesirable corner conditionsMinimum Corner RoundsKeeps the tool from getting into dead-stop state in cornersFinishing: Shallow AreasProjected type methodologyStraight machiningFlowline cut machiningProjected spiralMinimize

43、directional changesArc connectionsLoop connectionsSmooth approaches and exitsTangent SplineHelicalTangent arcAny approach/exit that yields little direction changeAdvantages for machines with rotary axes Shallow Areas Finishing: SettingsSurface Mill NC sequencesSequence Setup / Define Cut / Cut typeS

44、traight CutCutlineParameters:SCAN_TYPE = TYPE_3LACE_OPTION = ARC_CONNECTor LOOP_CONNECTSTEP_OVERShallow Areas Finishing: SettingsLoop Connections for Closed CutlinesCutlineSCAN_TYPE = TYPE_3LACE_OPTION = LOOP_CONNECTContinuous Helical CutlinesCutlineSCAN_TYPE = TYPE_HELICALFlat Areas Finishing: Sett

45、ingsVolume sequence for Flat surfacesParametersROUGH_OPTION = FACES_ONLYSCAN_TYPE = MAINTAIN_CUT_DIRECTIONor TYPE_SPIRALCUT_TYPE = CLIMBSTEP_OVER Must be 1/2 of TOOL_DIAMETERCLEAR_DISTOptional controls:RAMP_ANGLE CORNER_ROUND_RADIUSRest MillingNC sequences: Local / Prev ToolParametersSCAN_TYPE = TYP

46、E_1CUT_TYPE = CLIMBMACHINING_ORDER = CORNERS_FIRSTSURFACE_CLEANUP = SINGLE_PASSCORNER_CLEANUP = Z_PLANE_CUTSRETRACT_OPTION = SMARTSLOPE_ANGLE = 30STEP_DEPTH STEP_OVER RAMP_ANGLE CUT_ENTRY_EXT = HELIXCUT_EXIT_EXT = NONEINITIAL_ENTRY_EXT = HELIXFINAL_EXIT_EXT = NONELeftover materialPrevious ToolCurrent ToolPartPencil TracingNC sequences: Local / Pencil TracingParametersCUT_TYPE = CL