Embed Size (px)
Citation preview
w w w . a u t o s t e e l . o r g
SPRINGBACK AND SIDEWALL CURL CORRECTION ON DP600 AND TRIP 700 U-CHANNELS BY ELECTROMAGNETIC
PULSES
Edurne Iriondo LABEIN Tecnalia
w w w . a u t o s t e e l . o r g
OUTLINE
• Introduction• Electromagnetic Forming: Basic concepts• Springback• Springback correction
– Control of corner springback– Reshaping sidewall curvature
• Concluding remarks
w w w . a u t o s t e e l . o r g
INTRODUCTIONLABEIN Tecnalia
LABEIN is part ofTECNALIA Technology Corporation
w w w . a u t o s t e e l . o r g
INTRODUCTIONLABEIN Tecnalia - Automotive Unit
Operating in 5 markets:• Iron and steel• Automotive sector• Energy sector• Building• Regional Development
LABEIN is one of Europe’s most active organizations participating in European
Union R&D Programs
Bilbao, Spain
w w w . a u t o s t e e l . o r g
Automotive suppliers
ApplicationApplication FieldsFields• Forming Processes : sheet metal deep drawing, tubeforming (hydroforming), forging, punching / blanking, hot forming & electromagnetic forming.
• Functional development of components in chassismechanichs and fluid automotive systems
IntroductionLABEIN Tecnalia - Automotive Unit
w w w . a u t o s t e e l . o r g
Introduction
800 Ton Hydraulic Presswith hydroforming system
LABEIN Tecnalia - Automotive Unit
Capacitor BankMagneform ESCU 60 kJ
Biggest in Europe for R&D
w w w . a u t o s t e e l . o r g
OUTLINE
• Introduction• Electromagnetic Forming: Basic
concepts• Springback• Springback correction
– Control of corner springback– Reshaping sidewall curvature
• Concluding remarks
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF)
Rogowski Probe
Ring Specimen
Charging Circuit
Capacitor
Solenoid
Solenoid Current
Specimen Current
-20
-15
-10
-5
0
5
10
15
20
0 100 200 300 400
Cur
rent
(kA
)
Time (µs)
Primary current induces secondary current (in the part)
and the two fields repel causing part expansion.
Tube expansion
Primary current
Basic concepts
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF)
PROCESS CHARACTERISTICS:
• Deformation velocities achieved are : 50 - 250 m/sFor aluminium-steel and steel-steel couples impact pressures of 500Mpa and 1.4 Gpa are generated at velocity impact of 50 m/s.
• Strain rate in order of 103 & 104 s-1
• Total process time 200 µs
Basic concepts
w w w . a u t o s t e e l . o r g
Electromagnetic (EM) Forming
EM formed parts
EM Assembly Tube Compression Set up
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF) Tube compression
Solenoidal coil+
AA6063 Tube
Primary & Induced Currentsrunning in the coil and part
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF) Tube expansion
Numerical simulation gives force profileduring time interval defined by transient pulse
Current distributionon coil and tube
Force exerted in the piece
0
50000
100000
150000
200000
250000
300000
350000
400000
0 0,000005 0,00001 0,000015 0,00002
Time (seconds)
Forc
e (N
ewto
n)
Force acting on tube
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF) Sheet Metal Forming
Pressure distribution comparisons
3-bar coil
pancake coil
uniform pressure coil
Arrows indicate current direction
Energy: 0.8 kJ
Material: 0.13 mm Cu
w w w . a u t o s t e e l . o r g
Electromagnetic Forming (EMF)Sheet Metal Forming
Finite Element Analysis: Evolution during Forming
w w w . a u t o s t e e l . o r g
OUTLINE
• Introduction• Electromagnetic Forming: Basic concepts• Springback• Springback correction
– Control of corner springback– Reshaping sidewall curvature
• Concluding remarks
w w w . a u t o s t e e l . o r g
Springback
Higher strength ,
higher springback
Two channels made sequentially in the same die. Source www.worldauto.org
w w w . a u t o s t e e l . o r g
Springback
Angular change is caused by the stress difference in
the sheet thickness direction when a sheet
metal bends and unbends over a die radius. Complex stress state on the
sheet thickness.
w w w . a u t o s t e e l . o r g
OUTLINE
• Introduction• Electromagnetic Forming: Basic concepts.• Springback• Springback correction
– Control of corner springback– Reshaping sidewall curvature
• Concluding remarks
w w w . a u t o s t e e l . o r g
Springback correction Original idea
Why ?
through thicknessdeformation
(inertial ironing)
localized area
independent
+EM
pulse
=
The inertial ironing moves the neutral fiber out, controling the springback
w w w . a u t o s t e e l . o r g
Springback correction Control of corner
EXPERIMENTAL STUDY (I)Material:
- AA-5754 (1 and 2 mm thickness)
- DP-600 (0.8 and 1.95 mm thickness)
Blank measures: 100 X 170 mm
Electromagnetic coil
EM pulses in the radius area
Test configuration
w w w . a u t o s t e e l . o r g
Springback correction Control of corner
RESULTS
Energy vs. Springback angle
85
90
95
100
105
110
0 5 10 15
Energy (kJ)
Sprin
gbac
k an
gle
AA5754 - 1mmAA5754 - 2mmDP 600 - 0.8mmDP 600 - 1.95mm
w w w . a u t o s t e e l . o r g
Springback correction Control of corner
AA5754 of 1mm thickness.88°/ 2.4 kJ
89°/ 1.6 kJ
99°/ 0 kJ
90°/ 0.8 kJ
90°/ 14.4 kJ
91°/ 12.8 kJ
93°/ 9.6 kJ
97°/ 0 kJ
DP600 of 1.95mm thickness.
w w w . a u t o s t e e l . o r g
Springback correction Control of corner
MAIN PARAMETERS:
• CONDUCTIVITY OF THE MATERIAL. Aluminum’s conductivity is higher than steel’s. This is a key factor in the EMF.
The higher the conductivity of the sheet metal, the higher efficiency the system reaches higher peak currents obtained with the same input energy level
• THICKNESS. As the area of the pressure is constrained by the actuator’s geometry, the thickness of the material is an important parameter.
• STRENGTH.
w w w . a u t o s t e e l . o r g
Springback correction Reshaping sidewall curvature
SIDEWALL CURL Materials:
- DP-600 (1mm)
- TRIP-700 (1mm)
Blank measures: 100 X 300 mm
Test configuration
EM pulses to the sidewall curls as a second corrective step
EXPERIMENTAL STUDY (II)
w w w . a u t o s t e e l . o r g
Springback correction Reshaping sidewall curvature
14.4 kJ pulse Original
sidewall curl
90o
91o
Applying EM pulse only in one sidewall
Material: TRIP 700; 1mm thickness
w w w . a u t o s t e e l . o r g
Springback correction Reshaping sidewall curvature
19.2 kJ pulse
90o
Applying EM pulses in both sidewalls
Material: TRIP 700; 1mm thickness
90o
w w w . a u t o s t e e l . o r g
Springback correction Reshaping sidewall curvature
Plot comparing the different energy levels, averaged angles and materials
RESULTS: energy levels vs. angles
89.5
90
90.5
91
91.5
92
92.5
93
93.5
94
94.5
0 5 10 15 20 25 30
Energy (kJ)
Side
wal
l ang
le
DP 600TRIP 700
w w w . a u t o s t e e l . o r g
OUTLINE
• Introduction• Electromagnetic Forming: Basic concepts.• Springback• Springback correction
– Control of corner springback– Reshaping sidewall curvature
• Concluding remarks
w w w . a u t o s t e e l . o r g
• Springback can be corrected effectively on HSS by EM pulses
• The application of this innovative technique is very flexible and independent to other areas of the part.
• The tooling for this method is relatively simple and possible to couple it into an industrial system
Concluding remarks
