03_springbackcompensationseminar_stepbystep

Springback Springback CompensationCompensation SeminarSeminar

StepStep byby StepStep

Springback Springback CompensationCompensation Seminar, ChennaiSeminar, Chennai, July 9, 2010, July 9, 2010

2

Current Challenges

Physical tool geometry correction loops are timePhysical tool geometry correction loops are time-- and and costcost--intensiveintensiveSimulationSimulation--based springback compensation eliminates based springback compensation eliminates compensation loopscompensation loops

Accurate simulation Accurate simulation of springback of springback

Effective compensationEffective compensationof active surfaces of active surfaces

StartStart

Physical tryoutPhysical tryout

Simulation Simulation based tryoutbased tryout

Part geometryPart geometrySpringback resultSpringback result


3

Springback Compensation - Workflow

ToleranceToleranceokayokay??

CompensationCompensationstrategystrategy

* * SurfaceSurface constraintsconstraints* * CompensationCompensation factorfactor

CompensationCompensationactiveactive surfacessurfacesAF-Compensator

Process optimal?

Spring-back

robust?

Simulation ofSimulation ofRobustnessRobustness

AF-Sigma

Simulation ofSimulation ofSpringbackSpringback

AF-Incremental

Simulation Simulation ofofthethe processprocess

AF-IncrementalAF-DieDesigner

AF-Trim

Export ofExport ofcompensatedcompensated

active surfacesactive surfacesor vector field or vector field

Process & Geometry optimizationProcess & Geometry optimizationAF-Incremental, AF-DieDesigner

Springback Springback evaluationevaluation

Confirmation Confirmation Simulation Simulation

AF-Incremental


Springback Compensation The Principles

Principle 1: You require a proper basic simulationPrinciple 1: You require a proper basic simulationPrinciple 2: In order to execute a springback simulationPrinciple 2: In order to execute a springback simulation

Final Validation Settings are requiredFinal Validation Settings are requiredPrinciple 3: Evaluate springback in a well defined andPrinciple 3: Evaluate springback in a well defined and

repeatable wayrepeatable wayPrinciple 4: Ensure the process is stablePrinciple 4: Ensure the process is stablePrinciple 5: Compensation just does; it doesntPrinciple 5: Compensation just does; it doesnt

interpret or evaluateinterpret or evaluate

4


Springback Compensation Step by Step

Step 1: Proper Basic SimulationStep 1: Proper Basic SimulationStep 2: Simulation of SpringbackStep 2: Simulation of SpringbackStep 3: Springback EvaluationStep 3: Springback EvaluationStep 4: ProcessStep 4: Process-- and Geometryand Geometry--improvement improvement Step 5: Process RobustnessStep 5: Process RobustnessStep 6: Compensation StrategyStep 6: Compensation StrategyStep 7: Compensation active SurfacesStep 7: Compensation active SurfacesStep 8: Export Compensation ResultsStep 8: Export Compensation ResultsStep 9: Confirmation SimulationStep 9: Confirmation Simulation

5


Example

Springback Compensation Springback Compensation Step by Step will Step by Step will be be illustrated on one example: Sillustrated on one example: S--RailRailWe will make use of both:We will make use of both:

Slide PresentationSlide PresentationAutoForm Software DemonstrationAutoForm Software Demonstration

6


Step 1: Proper Basic Simulation

Step 1 identical to Principle 1Step 1 identical to Principle 1

Part must met the final quality demands before an accurate Part must met the final quality demands before an accurate springback simulation will be executedspringback simulation will be executed

Free of splitsFree of splitsFree of wrinklesFree of wrinklesFinal blank shapeFinal blank shape

Development of an optimal forming process using AutoFormDevelopment of an optimal forming process using AutoFormProcess layout, concept, draw die geometryProcess layout, concept, draw die geometryConsideration of all OPConsideration of all OPs, optimal Process parameters, optimal Process parameterClamping conditions of measuring deviceClamping conditions of measuring device

7


Preprocessing

Simulation setSimulation set--up of inner partsup of inner partsGeometry / Tools definitionsGeometry / Tools definitionsBlankBlank

Material dataMaterial dataBlank shapeBlank shape

Process definitionProcess definitionTool penetration Tool penetration kinematic checkkinematic checkDraw beadsDraw beadsSecondary operationsSecondary operations

8


Evaluation of Inner PartsEvaluation of Inner PartsGeneral Overview: General Overview: Formability Formability Analyze the Analyze the SplitsSplitsAnalyze the Distribution of Sheet ThicknessAnalyze the Distribution of Sheet ThicknessAnalyze the Analyze the Occurrence of WrinklesOccurrence of WrinklesAnalyze the Punch ImpactAnalyze the Punch ImpactAnalyze the Binder ClosureAnalyze the Binder ClosureAnalyze the Analyze the DrawDraw--InInCheck Check BlankholderBlankholder Pressure DistributionPressure Distribution

PostprocessingVersion 1.1

9


Forming of S-RailVersion 1.1

10

Part from AutoFormPart from AutoFormMaterial and thicknessMaterial and thickness

SPCC (2.00 mm)SPCC (2.00 mm)Binder TravelBinder Travel

100 mm100 mmBinder ForceBinder Force

600 KN (600 KN (apprappr. 60 ton). 60 ton)


Forming of S-RailVersion 1.1

11

Second Operation: Second Operation: CuttingCutting

FinallyFinally, Springback, Springback

First Operation: DrawingFirst Operation: Drawing


Software demo Step 1Version 1.1

12

Simulation setSimulation set--up Sup S--RailRail

ResultResult evaluation of Sevaluation of S--RailRail


Step 2: Springback Simulation

Final Validation SettingsFinal Validation SettingsConvergence behaviorConvergence behaviorFree springback vs. Constrained springbackFree springback vs. Constrained springback

Local best fitLocal best fitPositioning of clamps and pilotsPositioning of clamps and pilots

13


Version 1.1

14

Step 2: Springback simulation

Checklist: Checklist: Final ValidationFinal ValidationChecklist: Checklist: Final ValidationFinal Validation-- ElasticElastic PlasticPlastic ShellShell-- StandardStandard--settingssettings plus:plus:-- Initial Initial elementelement sizesize: :

2 2 * min. * min. DieDie--radiusradius (max(max. 20 . 20 mm)mm)-- Max Max refinementrefinement levellevel:: 5 5 -- Max Max elementelement angle: angle: 22.522.5-- EndTimeStepEndTimeStep: 0.4 : 0.4 --

AutoForm developed Final Validation Settings for a fast and AutoForm developed Final Validation Settings for a fast and accurate springback resultaccurate springback result

Starting point of Step 2 is Principle 2Starting point of Step 2 is Principle 2


Springback (x mm)Springback (x mm)Springback (x mm)

Compensation Strategy Influence of clamping conceptVersion 1.1

15

Springback (x mm) Springback(x mm)

StartingStarting Point Point Free SpringbackFree Springback

Constrained springback is always recommended in the Constrained springback is always recommended in the springback compensationspringback compensationTry to minimize the clamping pointsTry to minimize the clamping pointsTry to define the clamping concept with minimum Try to define the clamping concept with minimum springback deviation which aims at minimizing the surface springback deviation which aims at minimizing the surface change during the compensationchange during the compensationClamping concept influences the springback resultsClamping concept influences the springback results

ConstrainedConstrainedSpringbackSpringback

ConstrainedConstrainedSpringbackSpringback


Positioning of Clamps

In reality,In reality, the the Sheet has a certain Sheet has a certain thicknessthicknessClamp position is well definedClamp position is well defined

In the simulation, only the In the simulation, only the mid plane of the sheet is mid plane of the sheet is representedrepresentedThe clamp position must The clamp position must be defined carefully:be defined carefully:TopTop -- Mid Mid -- BottomBottom

16


Step 3: Springback Evaluation

Clamping Concept & Clamping ForcesClamping Concept & Clamping ForcesReference GeometryReference GeometrySpringback resultsSpringback results-- distance from referencedistance from reference

Springback result variables are always measured from part to Springback result variables are always measured from part to reference geometryreference geometry

Reference GeometryReference Geometry

Part after SpringbackPart after Springback

17


Software Demo Step 2 & 3

Step 2: Springback SimulationStep 2: Springback SimulationStep 3: Springback EvaluationStep 3: Springback Evaluation

Evaluation of clamping forcesEvaluation of clamping forcesEvaluation of springback values Evaluation of springback values

The shape deviation varies from -3.5mm to 0.4mm, which exceeded the given tolerance, therefore, springback compensation is necessary.

18


Step 4: Process- & Geometry- improvement

Modification of:Modification of:Process settingsProcess settingsTool GeometryTool GeometryPart GeometryPart Geometry

in order to reduce or even eliminate springbackin order to reduce or even eliminate springback

In case of the SIn case of the S--Rail, Rail, blankholderblankholder force just before bottom force just before bottom stroke has been increasedstroke has been increased

19


Part 1: accurate springback simulationPart 1: accurate springback simulationStep 1: Proper Basic SimulationStep 1: Proper Basic SimulationStep 2: Springback SimulationStep 2: Springback SimulationStep 3: Springback EvaluationStep 3: Springback EvaluationStep 4: ProcessStep 4: Process-- and Geometryand Geometry--Improvement Improvement

Part 2: effective springback compensationPart 2: effective springback compensationStep 5: Process RobustnessStep 5: Process RobustnessStep 6: Compensation StrategyStep 6: Compensation StrategyStep 7: Compensation active SurfacesStep 7: Compensation active SurfacesStep 8: Export Compensation ResultsStep 8: Export Compensation ResultsStep 9: Confirmation SimulationStep 9: Confirmation Simulation

20


Version 1.1

21

Step 5. Process Robustness

InputInput

O

u

t

p

u

t

O

u

t

p

u

t

RobustnessRobustnessThe characteristic of the process to be insensitive The characteristic of the process to be insensitive to the variation of the inputto the variation of the input

Initial SimulationInitial Simulation

Improved simulationImproved simulation

Material variation at Material variation at improved simulationimproved simulationNew SimulationNew SimulationMaterial variation at Material variation at new Simulationnew Simulation

RobustnessRobustnessAnalysisAnalysis

Process Process improvementimprovement


Version 1.1

22

Robustness Analysis - how does it work?

Noisevariables

Definition of Process Environment Multiple Simulations

Evaluation, Statistic process control

Influence and sensitivity

Process potential

Dominant variable


Version 1.1

23

Industrial Application of Robustness Analysis

Front Front sideside membermember innerinner Volvo C30/S40/V50 Volvo C30/S40/V50 ((**))

((**

) ) Influence on simulation results from material and process scatter, Sigvant & Carleer, IDDRG, Porto 2006Influence on simulation results from material and process scatter, Sigvant & Carleer, IDDRG, Porto 2006


Version 1.1


FailureFailure

Simulation showed a feasible Simulation showed a feasible partpart

1.01.00.80.80.60.6

24


Version 1.1


but despite of a safe simulation occurrence of but despite of a safe simulation occurrence of problems problems in productionin production

25


Version 1.1


InputInput OutputOutput

Specificationlimit

26


Version 1.1

Industrial Application of Robustness AnalysisModification of radius in critical zone resulted Modification of radius in critical zone resulted in a more stable production processin a more stable production process

OutputOutput

Specificationlimit

OutputOutput

Specificationlimit

27


Version 1.1

Industrial Application - Summary

InputInput

O

u

t

p

u

t

O

u

t

p

u

t

OutputOutput OutputOutput

Process improvement II &Process improvement II &Robustness analysis IIRobustness analysis IIpart is feasible and part is feasible and production is reliableproduction is reliable

Robustness analysis IRobustness analysis Ipart production is not part production is not reliable reliable

Process improvement IProcess improvement Ipart is feasible part is feasible

28


Step 5. Process RobustnessVersion 1.1

29

InputInput OutputOutput

It is strongly recommended to assure that your process is stable by It is strongly recommended to assure that your process is stable by using AutoFormusing AutoForm--Sigma. Compensations is only reasonable with a Sigma. Compensations is only reasonable with a robust springbackrobust springback

FormingFormingprocessprocess

4.31.0 8.7

(Springback,(Springback,mm)mm)

How much must the tool be compensated?How much must the tool be compensated?Compensation doesnt guarantee success Compensation doesnt guarantee success

AutoForm developed an inputAutoForm developed an input--set for AutoFormset for AutoForm--Sigma in order to Sigma in order to properly represent the real life result variationproperly represent the real life result variation

Step 5 is identical to Principle 4: ensureStep 5 is identical to Principle 4: ensure the process is stablethe process is stable


Robustness Analysis - InputVersion 1.1

30

Parameters & Ranges forParameters & Ranges for robustness analysisrobustness analysisThickness, Thickness, Norm Norm 10% 10% Mechanical Properties, Rp0.2 Mechanical Properties, Rp0.2 20MPa, 20MPa, RmRm 20MPa (dependent )20MPa (dependent )RR--Values, Values, 20% (dependent ) 20% (dependent ) Blank holder pressure, Blank holder pressure, 10%10%Lube, Lube, 10%10%Blank position, Blank position, 1mm1mm


Software Demo Step 5: Process Robustness

Process Robustness with respect to:Process Robustness with respect to:FeasibilityFeasibilitySpringbackSpringback

31


Step 6. Compensation strategy

Carefully consider how to compensate the forming Carefully consider how to compensate the forming processprocess

Which operation etc.Which operation etc.Surface constraintsSurface constraintsCompensation factor (Default = Recommendation = 1)Compensation factor (Default = Recommendation = 1)

32


Version 1.1

33

Compensation Strategy A: Structural Parts

OP20:OP20:GravityGravityClosingClosingDrawingDrawing

OP40:OP40:CuttingCutting


OP60:OP60:CuttingCuttingSpringbackSpringback


Vector Vector field of OP60 is processed on part geometry field of OP60 is processed on part geometry ((--> > all operations are compensated same as OP20)all operations are compensated same as OP20)After After OP60 springback of part should be within required tolerances OP60 springback of part should be within required tolerances otherwise additional otherwise additional compensation loops are compensation loops are requiredrequiredBecause of different springback at the end of each operation, Because of different springback at the end of each operation, problems while loading following die might occurproblems while loading following die might occur


Version 1.1

34

Compensation Strategy B: Structural Parts

Each Each forming operation forming operation is compensated individually is compensated individually After After OP50 springback of part should be within required OP50 springback of part should be within required tolerances tolerances otherwise additional compensation loops are requiredotherwise additional compensation loops are requiredBecause of different compensation geometries of each operation, Because of different compensation geometries of each operation, positioning in next tool must be done carefullypositioning in next tool must be done carefully

OP20:OP20:GravityGravityClosingClosingDrawingDrawingSpringbackSpringback


OP40OP40::PositioningPositioningClosingClosingFormingFormingSpringbackSpringback

OP50OP50::PositioningPositioningClosingClosingFormingFormingSpringbackSpringback


Compensation StrategyVersion 1.1

35

Springback (x mm)

Free springback)Free springback)

OP20:OP20:GravityGravityClosingClosingDrawingDrawing


OP40OP40::FormingForming

OP50OP50::FormingFormingSpringbackSpringback

Springback (x mm)

ConstrainedConstrained springbackspringback


1ste Iteration (x mm)




First First compensationcompensation looploop

Strategy A -Version 1.1

36

StartingStarting pointpoint

Springback(x mm)

Springback (y mm)

2te Iteration (y mm)




Second Second compensationcompensation looploop

Springback OK


Step 7: Compensation of Active Surfaces

Application of AutoFormApplication of AutoForm--CompensatorCompensator

Keep in mind Principle 5: Keep in mind Principle 5: Compensation just does; it doesnt interpret or evaluateCompensation just does; it doesnt interpret or evaluate

37


Version 1.0

Springback Compensation

ExampleExample: : CompensationCompensation ofof a Cross a Cross membermember

The The formingforming, , cuttingcutting andand springback springback hashas to to bebe calculatedcalculated asas basisbasis forfor thethecompensationcompensation..

As As thethe entireentire tooltool geometrygeometry isis to to bebe compensatedcompensated in in thethe DrawDraw stagestage, , ModMod 22 hashas to to bebe selectedselected..

38


Version 1.0


ExampleExample: : CompensationCompensation atat a Cross a Cross membermember

UsingUsing thethe PredefinePredefine compensationcompensation regionsregions, , thethe areasareas forfor thethecompensationcompensation areare determineddetermined automaticallyautomatically..

BinderBinder: The : The defineddefined binderbinder isis fixedfixed ((FixedFixed).).PartPart: The original : The original partpart datadata areare compensatedcompensated accordingaccording to to thethe springback springback resultsresultsbyby thethe factorfactor 11. . FillFill andand AddendumAddendum definedefine thethe transitiontransition areaarea..

39


Version 1.0


Example: Compensation at a Cross memberExample: Compensation at a Cross memberAfter After ApplyApply the tool surfaces are modified.the tool surfaces are modified.

In the section, the sprung back part, the reference geometry and the In the section, the sprung back part, the reference geometry and the compensated punch are shown. compensated punch are shown. The part is sprung back upwards with respect to the reference The part is sprung back upwards with respect to the reference geometry. geometry. Thus, the geometry is corrected in the opposite direction, Thus, the geometry is corrected in the opposite direction, accordingly. The punch (as all the other tools in the Process accordingly. The punch (as all the other tools in the Process generator) is automatically adopted and is positioned below the generator) is automatically adopted and is positioned below the reference geometry.reference geometry.

StempelStempelReferenzgeometrieReferenzgeometrie

aufgefedertes Bauteilaufgefedertes Bauteil

Reference GeometryReference GeometryNew PunchNew Punch

Sprung back PartSprung back Part

40


Springback CompensationVersion 1.1

41

Compensation area of the SCompensation area of the S--RailRailDirect compensation is only possible in those area where springback Direct compensation is only possible in those area where springback results are available.results are available.


Principle 5: Compensation just doesVersion 1.1

42

First compensation loopFirst compensation loopStraight forward compensation gives swinging of the Straight forward compensation gives swinging of the blankholderblankholderManual manipulation necessaryManual manipulation necessary

Think of principle 5: compensationThink of principle 5: compensation just doesjust doesThe compensation just takes the available springback result to The compensation just takes the available springback result to extract the toolextract the tool geometry, no further interpretation or evaluation has geometry, no further interpretation or evaluation has been done been done

For beam-like part or the case of part on binder, the quality of binder surface after compensation is the typical issue.

Improve the distorted binder surface


Smooth Binder SurfaceVersion 1.1

43

Desired shape

Improved binder surface

Manual manipulationManual manipulation executed with morphing functionality of executed with morphing functionality of AutoFormAutoForm--DieDesignerDieDesignerBlankholderBlankholder looks smooth nowlooks smooth now


The max. shape deviation still exceeded the given The max. shape deviation still exceeded the given tolerance after one compensation loop.tolerance after one compensation loop.Introduce 2Introduce 2ndnd and 3and 3rdrd compensation until given tolerance is compensation until given tolerance is reachedreached

Version 1.1

44


Convergence of Compensation LoopsThe convergence behavior can be both oscillating or The convergence behavior can be both oscillating or asymptotic (impossible to say in advance what it will be)asymptotic (impossible to say in advance what it will be)

0 1 2 3 4 5# iteration loop

D

i

s

t

a

n

c

e

f

r

o

m

r

e

f

e

r

e

n

c

e

0

oscillating oscillating convergenceconvergenceasymptotic asymptotic convergenceconvergence

45


Software demo Step 6 & 7

Step 6: Compensation StrategyStep 6: Compensation StrategyStep 7: Compensation Active SurfacesStep 7: Compensation Active Surfaces

The final shape deviation after 4 compensation loops The final shape deviation after 4 compensation loops The shape deviation is wellThe shape deviation is well--controlled under 0.25mmcontrolled under 0.25mm

Version 1.1

46


Software demo Step 6 & 7

The final shape deviation after 4The final shape deviation after 4thth Compensation loops Compensation loops The shape deviation is wellThe shape deviation is well--controlled under 0.25mmcontrolled under 0.25mm

Version 1.1

47

Starting point 1st Iteration

4th Iteration


Step 8: Export Compensation Results

How to get the data out of AF into a CAD system?How to get the data out of AF into a CAD system?Export compensated meshExport compensated meshImport in CADImport in CADReRe--design in CAD based on imported AFdesign in CAD based on imported AF--compensatedcompensated meshmeshIn special cases, use vector field to deform existing CADIn special cases, use vector field to deform existing CAD--surfacessurfaces

48


Step 9: Confirmation Simulation

49

Execute anExecute an AutoForm simulation based on the AutoForm simulation based on the compensated tool surface as final check before millingcompensated tool surface as final check before milling


Version 1.1Version 1.1

50

Springback Compensation - Workflow

ToleranceToleranceokayokay??

CompensationCompensationstrategystrategy

* * SurfaceSurface constraintsconstraints* * CompensationCompensation factorfactor

CompensationCompensationactiveactive surfacessurfacesAF-Compensator

Process optimal?

Spring-back

robust?

Simulation ofSimulation ofRobustnessRobustness

AF-Sigma

Simulation ofSimulation ofSpringbackSpringback

AF-Incremental

Simulation Simulation ofofthethe processprocess

AF-IncrementalAF-DieDesigner

AF-Trim

Export ofExport ofcompensatedcompensated

active surfacesactive surfacesor vector field or vector field

Process & Geometry optimizationProcess & Geometry optimizationAF-Incremental, AF-DieDesigner

Springback Springback evaluationevaluation

Confirmation Confirmation Simulation Simulation

AF-Incremental


Version 1.1

51

Influence on your Working-Process

ToolProduction Tryout

Tool Design

ProcessPlanningFeasibility

Future Procedure:Future Procedure:The process engineer develops a compensationThe process engineer develops a compensationstrategy at an early stagestrategy at an early stageThe necessary springback and compensation The necessary springback and compensation knowknow--how has been developedhow has been developedThe active surfaces are already compensated The active surfaces are already compensated in the engineering department. in the engineering department.

Tryout samples have been measuredTryout samples have been measuredA compensation strategy is determinedA compensation strategy is determinedGenerally the process engineer is not involvedGenerally the process engineer is not involved

Present Procedure:Present Procedure:


Tips for Successful Implementation

Before Springback compensationBefore Springback compensationThe base simulation should have no splits, no wrinkles and no The base simulation should have no splits, no wrinkles and no issues of blank size change;issues of blank size change;Springback should be minimized through process improvement.Springback should be minimized through process improvement.

Springback compensationSpringback compensationThe distortion of binder surface after compensation is the typical The distortion of binder surface after compensation is the typical issue of compensation for beamissue of compensation for beam--like part, or the case of part on like part, or the case of part on binder;binder;To improve the binder surface, additional morph has to be To improve the binder surface, additional morph has to be introduced.introduced.Attention: Only the fix region and transition region can be Attention: Only the fix region and transition region can be modified after compensation. The region of direct compensation modified after compensation. The region of direct compensation is not allowed to be changed after compensation. is not allowed to be changed after compensation.

Version 1.1

52


Tips for Successful Implementation

After Springback compensation, After Springback compensation, Inform the tryInform the try--out worker that this is a compensated tool so the out worker that this is a compensated tool so the process must be adjusted to the simulation as much as possibleprocess must be adjusted to the simulation as much as possibleBe present at the tryBe present at the try--out to learn and to discus any additional out to learn and to discus any additional change of tool surfaceschange of tool surfaces

Version 1.1

53


Version 1.1

54

Summary and Perspective

Springback simulations can reliably be performed with Springback simulations can reliably be performed with AutoForm Final Validation settingsAutoForm Final Validation settingsSpringback compensation can productively be applied using Springback compensation can productively be applied using AutoFormAutoFormCompensation strategies can be complexCompensation strategies can be complexSpringback simulation and springback compensation require Springback simulation and springback compensation require additional expertise of the useradditional expertise of the user

AutoForm offers you support AutoForm offers you support for the implementation of for the implementation of this leading edge technology this leading edge technology


Version 1.1

55

Thank YouThank You

03_springbackcompensationseminar_stepbystep

Documents

based springback compensation

springback compensation

springback simulationprinciple

springback evaluationstep

compensation strategystep

simulation of springbackstep

process robustnessstep

proper basic simulationstep