elastomers as a flexible tooling surface - iom3 · reverse engineering of materials for ......

Elastomers as a flexible tooling surface

Vacuum Assisted Multipoint Tooling for Producing

Spatially Curved Single-Item CFRP Panels

Matthias Wimmer

Munich University of Applied Science

Hier wird der Titel der Präsentation wiederholt (Ansicht >Folienmaster)Elastomers as a flexible tooling surface

Matthias Wimmer, Department of Mechanical Engineering, [email protected]

... if a flat piece costs one dollar and a single curvature piece costs two dollars then a double curvature piece costs ten dollars. This is true for all materials wood,

metal, plastic, glass, concrete ...

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Lindsey, Bruce; Gehry, Frank O. (2001): Digital Gehry. Material resistance, digital construction. Basel: Birkhäuser



Overview

multipoint tooling

manufacturing of CFRP panels

challenges and solutions

conclusion and outlook

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MULTIPOINT TOOLING

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Basic Idea

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Curtis Lawrence (2008), Pinpression Animated, Youtube.com



Basic Idea

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First invention

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Cochrane, John (1862): Improvement in presses for bending metallic plates, US patent 39,886



Concept

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solid mould multipoint tool

interpolation layer

(elastomer)

pin array



Recent Developments

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3D Former for manufacturing PMMA windshields (Munich University of Applied Science, 2009)



MANUFACTURING OF CFRP PANELS

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Manufacturing Processes

wet layup vacuum bagging

vacuum infusion prepreg moulding

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Process Chain

Part design

•CAD design

Mould design

•warp calculation •CAD mould

design

CAM

•CNC programing

Mold manufacturing

•milling •grinding•polishing

Part manufacturing

•application of release agent•fabric layup•curing

Moulds end of life

•mold storage•mold revision•recycling

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1-5 days 1 day 1-2 days 1-2 days



CHALLENGES AND SOLUTIONS

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Challenges in tool design

existing tools are limited in geometric complexity

only convex shapes can be created

standard CFRP manufacturing processes are not usable

shape accuracy of at least .5 mm has to be achieved

elevated temperatures destroy interpolation layer

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Vacuum Assisted Multipoint Moulding

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interpolation layer in tenter frame

pin array

threaded rods

vacuum container

base plate actuator couplings



Challenges to achieve high quality

dimpling

shape deviation

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desired shape

actual shape

Source: Dunarea de Jos University of Galati



Ideal interpolation layer

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Single Layer IPL

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Single Layer IPL

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Single Layer IPL

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Dimpling [mm]



Simulation results

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30

35

40

45

50

55

0 10 20 30 40 50 60 70 80

Y [

mm

]

X [mm]

Sphere with radius 218 mm with different IPL thicknesses

24 mm

18 mm

12 mm

6 mm

desired shape



Exemplary measurements

15 mm

10 mm

5 mm

300mBar 600mBar 900mBar



Interpolation layer

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Shape deviation control

Closed Loop shape control using FEA model of theforming process

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Valjavec, Marco (1999): A Closed-loop Shape Control Methodology for Flexible Stretch Forming over a Reconfigurable Tool. Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts



Simulation results

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30

35

40

45

50

55

0 10 20 30 40 50 60 70 80

Y [

mm

]

X [mm]

Sphere shape (r=218 mm) with different IPL thicknesses –shape error corrected

24 mm

18 mm

12 mm

6 mm

desired shape



Proposed solutions

Multi layer IPL:

Soft, incompressible material in low layer too fillgaps

Hard material on top too smoothen out dimplesand create a viable surface

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Multilayer IPL

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30

35

40

45

50

55

0 10 20 30 40 50 60 70 80

Y [

mm

]

X [mm]

Sphere with radius 218 mm with 12 mm IPL (single/multilayer)

desired shape

multilayer 10+2

12 mm

Multilayer IPL

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Dsl

Dml

Serr_slSerr_ml



Manufacturing test

Picture of produced part (with grid on it?)

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Reference part

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CONCLUSION AND OUTLOOK

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Conclusion

Dimpling is a problem in vacuum assisted multipoint tooling.

With a single layer of the tested material an interpolation layer thickness equal to the pin diameter is sufficient to prevent dimpling in vacuum assisted multipoint tooling.

The multilayer approach can decrease dimpling more sufficiently than a single layer IPL.

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Outlook

testing of the IPL behaviour with real materials and measured material parameters

sensitivity analysis of different parameters influencing IPL behaviour

numeric optimization of the layer design

reverse engineering of materials for use in multilayer IPL

manufacturing and test of multilayer IPL

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Outlook

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Part design

•CAD design

CAM

•Warp calculation•Pin position

extraction

Tool setup

•Pin adjustment

Part manufacturing

•fabric layup•curing

1 hour 1-3 hours 1-2 days

Part design

•CAD design

Mould design

•warp calculation •CAD mould

design

CAM

•CNC programing

Mold manufacturing

•milling •grinding•polishing

Part manufacturing

•application of release agent•fabric layup•curing

Moulds end of life

•mold storage•mold revision•recycling



Outlook

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Thank you very much.

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Contact

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Matthias WimmerResearch Assistant

Project FlexForCFK

Competence Centre for Product- und Organisation Development

Dachauer Str. 98b | 80335 Munich | Germany Telephone: +49 (0) 89/1265 - 3389E-Mail: [email protected]

Competence CentreProduct and Organisation Development

elastomers as a flexible tooling surface - iom3 · reverse engineering of materials for ......

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