A. Mentella ifu-hydro

Italian
Design…
Why make it
simple?
When you can
make it beautiful…
Source: Wikimedia commons Copyright © ESI Group, 2010. All rights reserved.

New Potential Applications for Tube and
Sheet Hydroforming
in Furnishing and Household Hardware

Dr. Alessia Mentella, ESI Italy
Prof. Matteo Strano, Politecnico di Milano
Dr. Martin Skrikerud, ESI Group

Fellbach-Stuttgart/Germany
May 6th , 2010
Copyright © ESI Group, 2010. All rights reserved. 2

About ESI

Provider of Virtual Prototyping for the Industrial World

ESI is a world leading software editor for the numerical simulation of prototype
and manufacturing process engineering in applied mechanics.


ESI Worldwide Operations

More than 30
countries

15 subsidiaries

Average
Headcount:
750 people

Tokyo, Japan

Paris, France Eschborn, Germany Pilsen, Czech Republic San Diego, CA, USA Beijing, China


Selected Customer References


AGENDA
Introduction
Stainless steel in household Aesthetical requirements and
hardware geometrical complexity

Forming processes with solid tools
Cruet stand Vase Sauce pan

Fluid forming processes
DSHF - Vase THF – Cruet stand

Comparison
Vase Cruetstand

Conclusions

INTRODUCTION
Stainless
Steel

Hygienic and Excellent
Corrosion
Surface look polished cold
resistance
surfaces formability


FORMING PROCESSES WITH
SOLID TOOLS
Conventional deep drawing

ADDITIONAL DRAWING INVERSE DRAWING


SOLID TOOLS
ALESSI’s Cruet stand
Production cycle
Initial blank:
AISI 304 disk
D=300mm
t=0.8mm.
1° deep drawing 2° deep drawing 3° deep drawing 1° trimming

global annealing 4° deep drawing 5° deep drawing 2° trimming
5 punch/die set,
2 annealing
3 necking.

Total: 8 dies and
partial annealing 1° necking 2° necking 3° necking 5 punches.


SOLID TOOLS
ALESSI’s “Babyboop” Vase
Production Cycle
Initial blank:
2 AISI 304 2B
rectangles;
428,5mm x 312,5mm
1° deep drawing 2° deep drawing
t=1mm for
EACH
HALF

trimming of the borders trimming of the hole

JOINING

welding of the two halves welding of the bottom


TOWARDS FLEXIBILITY

Rubber Forming of “Olympia” Saucepan

Production cycle

1st deep-drawn raugh-hewn 2nd deep-drawn raugh-hewn ending edge trimming.
and annealing. and calibrating.

formed part (left), polymeric punch (centre), semi-finished part (right)


FLUID FORMING PROCESSES

Double Sheet Hydroforming

Closing Forming Calibrating

Flexforming

Positioning Forming Relift


FLUID FORMING PROCESSES
Tube Hydroforming

1.The workpiece is 2.The die is closed 3.The fluid fills
positioned between the tube cavity
the dies

4.The tube ends are 5.The tube is formed by 6.The dies open and
sealed the increasing pressure the workpiece is
and the punch stroke removed



FEM Modeling of ALESSI’s “Babyboop” Vase

σ(εp)=K(ε0+ εp)n
4-nodes shell elements with 5 integration
points throughout the thickness

ρ E [GPa] ν K [GPa] ε0 n
AISI304
7.8·10E-06 210 0.3 1.1153 0.017 0.336

time [ms] 0 6 18 20
P [GPa] 0 0.025 0.035 0.13


ALESSI’s Vase - RESULTS


Tube hydroforming – axial feeding

1. DOUDLE SHEET HYDROFORMING WITH
Aesthetical
FLEXIBLE MEMBRANE
Welding line along the cruetstand axis, for the joining
requirements non
of the two shells completely fullfilled

2. TUBE HYDROFORMING - SELF FEEDING Lenght of the
1° Hydroforming – Annealing – 2°Hydroforming process quite hight

The system is complex
3. TUBE HYDROFORMING - AXIAL FEEDING but the part is formed in
a single operation



ρ E [GPa] ν K [GPa] ε0 n
AISI304
7.8·10E-06 210 0.3 1.1153 0.017 0.336

time [ms] 0 0.66 1 3 4 5
P [GPa] 0 0.01 0.0135 0.016 0.0161 0.08
time [ms] 0 2 3
vel DX [mm/ms] 20 20 0
vel SX [mm/ms] 2 2 0



ALESSI’s Cruet stand – Induced wrinkling

1 2

4 3



ALESSI’s Cruet stand – RESULTS


COMPARISON - Vase

“Babyboop Vase” Conventional DDR DSHF
Forming 4 (2 for each half) 1
Annealing 0 0
Special operation for
0 0
undercuts solving
3 (initial blank + border + hole)
Trimming 2 (border + hole) for each half
for each half
Welding 2 (two halves + bottom) 2 (two halves + bottom)
n° Dies 1 1
Total op. 10 8
20s x 2 (forming) + 25s (forming) +
25s (trimming) + 25s (trimming) +
Manufacturing Time 15s (welding of two halves) + 15s (welding of two halves) +
8s (bottom welding) = 88s 8s (bottom welding) = 73s


COMPARISON – Cruet stand

Tube Hydroforming
“Mami Cruetstand” Conventional DDR DSHF
Self feeding Active feeding
Forming 5 1 3 1
Annealing 1° global - 2° local 0 2 0
Special operation for
3 0 0 0
undercuts solving
Trimming 3 2 (1 for each half) 1 1
3 (upper ring + bottom 2 (upper ring + 2 (upper ring +
Welding 1 (upper ring)
+ body) bottom) bottom)
n° Dies 5 1 1 1
Total op. 14 6 8 4
60s (5 forming) +
25s (forming) + 50s (3 forming) +
14s (1°annealing) + 20s (forming) +
20s (2 trimming) + 20s (2 annealing) +
7s (2°annealing) + 5s (trimming) +
4s (top ring welding)+ 5s (trimming) +
Manufacturing Time 30s (3 necking) + 4s (top ring welding)+
6s (bottom welding) + 4s (top ring welding) +
10s (3 trimming) + 6s (bottom welding)
15s (body welding) 6s (bottom welding)
4s (top ring welding) = 35s
= 70s = 85s
= 125s


CONCLUSIONS

Aesthetics in manufacturing:
In the case studies discussed, the designer’s vision and its
aesthetic dictates have been successfully combined with
technological requirements:
• joints and welding lines are significantly reduced
• the production is simplified in terms of number of operation and
needed dies
• Problems with possible undercuts in deep drawing are eliminated
• if the press is available, the costs for the component production
could be lower.


CONCLUSIONS

Hydroforming processes, both THF and SHF, can be
successfully used in fields that is very different from the
classical automotive or aerospace
It offers a real alternative when paying respect to the
aesthetical aspect of the component, instead of resistance
or strength.

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A. Mentella ifu-hydro

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