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SHEET METAL PART QUALITY IMPROVEMENT THROUGH DIE

OPTIMIZATION USING AUTOFORM

AIRIC2015

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OBJECTIVES:

Improvement of simulation accuracy and standardizing of sheet metal forming simulation

Phase transition of die quality improvement from final design to simulation and early CAD surface design

Decreasing of part development time Decreasing of part total cost

3Causes of project

Need in improvement of AUTOFORM predictions and results

Time and cost waste during manufacturing and sheet metal part development

Poor dimensional accuracy in past projects

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1. Past method of simulation in AIRIC2. Important effective parameters3. Numerical and simulation investigations4. Experimental and real results 5. Results verifications

1. Optimization methodology2. Optimization of die surface based on successful try-out3. Optimization of die surface based on successful high production

rate

First part

Second part

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Current method of simulation in AIRIC

There is no difference in simulation setup considering type of operation and die size

First part

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Effective ParametersParameter G1 G2 G3 G4 G5

Error tolerance 0.1 0.1 0.1 0.05 0.05Max side length 30 30 20 10 10

Global sharp & fillet edge 1 1 1 1 1Global radius 3 3 3 3 3Max radius D D D D D

Max element angle 20 20 20 20 20Max radius penetration 0.16 0.16 0.16 0.16 0.16

Initial element size 2*R min 2*R min 2*R min 2*R min 2*R minInitial number of element          

Max refinement level 7 7 6 5 5Max displacement 0.22 0.22 0.22 0.16 0.16

Refinement extension D D D 2.5 2.5Tangential refinement ON ON ON ON ONBoundary penetration 0.11 0.11 0.11 0.11 0.11

Stiffness value <10 30 50 100 >100Transient softening D D D D D

Stagnation ratio D D D D DYoung reduction factor D D D D DYoung reduction rate D D D D D

Number of end time step s 6 4 4 4 4End time step 0.2 0.4 0.4 0.4 0.4

Drawbead plastification ON ON ON ON ONBinder wrap steps          

Crack limit D D D D DTool opening ON ON ON ON ON

Tool penetration to post D D D D D

D: dependent

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Criteria of parameters categorizing

Type of operation Thickness of sheet metal Part complexity

HOLDER BRKT – G5REINF-ANCHORAGE LWR– G3

WHEEL HOUSE-G3

Standard simulation is the current method of simulationModified simulation is simulation based on parameters and values were listed in page 6

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REINF-ANCHORAGE LWR

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Verification of simulation results

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FEM correlation OF wheel house

Experimental data:

Standard setting( 3.848mm)

Fine Setting(3.475mm)

User defined setting(2.734 mm)

×

11STROCKE AT ONCET OF FAILURE (SOF)

SOF: 53 mmMesh size: 4mm

SOF: 54.8 mmStandard setting of Autoform

MAT: SAPH 440Thickness: 2mmTonnage: 65 TN

SOF: 52 mmMesh size: 3mm

SOF:55.764 mmMesh size: 6mm

SIMPLE CUP DRAWING COMPARISON IN ONCET OF FAILURE USING AUTOFORM AND ABAQUS PREDICTIONS

SOF: 40 mmMesh size : 3 mm

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Load - displacement

0 10 20 30 40 50 60 70 80 900

10000

20000

30000

40000

50000

60000

70000

AUTOFORM-ROUGH.AUTOFORM-FINEABAQUS-MESH3AUTOFORM-MESH4AUTOFORM-MESH3

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COMPARISON OF THICKNESS DISTRIBUTION BETWEEN ABAQUS AND AUTOFORM MODIFIED

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Sample done projects

1. Feasibility phase

2. Die surface design

3. Manufactured die

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REINF RR HANGER BRKT, LH

DRAWBEADUNKNOWN

Drawbead design and optimization

Effect of drawbead design on failure prevention

Existence of failure on part

Feasibility phase

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FR DOOR OTR RR VIEW MIRROR MTG PLATE UPR, LH

Existence of failure on part

Subjected fillet design and optimization

Feasibility phase

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C-PILLAR UPRDie surface design

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Extreme failure all around drawn part

Die surface design

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Defect source

Absence of material flow

Lowest price solution

Drawbead design and optimization

Presence of flow and successful drawing

Die surface design

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COMPARISON OF FLOW BEFORE AND AFTER OPTIMIZATION

Die surface design

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Die surface design

Improvement part quality

Three different area optimization

Reaching minimum springback amount of 0.75 mm

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BUMPER CENTERDie surface design

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SPRING BACKDie surface design

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Problem on part: severe failure & wrinkle on part

Solution: drawbead optimization based on lowest cost in order To eliminate failure and minimized springback

WHEEL HOUSE,RR Manufactured die

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unknown38%

B12%B2

4%

B39%

B47%B5

4%

B67%

B73%

B82%

B92%

B103%

D14%

D23% D3

7%

D52%

D63%

D72%

formability objecftive function

B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 D1 D2 D3 D4 D5 D6 D70

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2

3

4

5

6

7

8

9

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Manufactured die

Here there are parameters which affect formability of part

Above parameters are sections of drawbead

B-PILLAR-INR-EXTENSION Manufactured die

Manufactured die

Existence of severe failure on part

Manufactured die

Optimized areas Successful product

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Distance blocks thicknessCushion pin variable Blank locators (Blank position deviation)

Optimization of die surface based on successful high production rate

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SPRING BACK DURING TRY-OUT

Cpk = 1Cpk = 1.33Cpk = 0.66

SPRING BACK DURING PRODUCTION

UNKNOWN21%

X-B72%

Y-B5%

X-D1%

Y-D2%

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Thank you for your attention