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© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 1 www.kuka.com
3-DIMENSIONAL FRICTION STIR WELDING USING A KUKA HIGH PAYLOAD ROBOT
Details and contact
Otto Kellenberger, M.Eng. – KUKA Roboter GmbH
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 2 www.kuka.com
Introduction
shoulder
pin
plunging in
friction heatis generated
welling
D
welding retractingProcess description
2 mm
NuggetTMAZHAZ
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 3 www.kuka.com
Special FSWmachines
CNCmilling machines
source: Heller
ParallelkinematicSystems(Tripods,
Hexapods)
Articulated armrobots
source: ESAB
Different machine concepts suitable for FSW
Introduction - Relevant machine types for FSW
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 4 www.kuka.com
���� Articulated arm robots represent a flexible tool, which are suited for FSW
on thin profiles (0,3 mm to 8 mm Al alloy, 2xxx, 5xxx, 6xxx, 7xxx).
Comparison
advantageousadvantageous balancedbalanced less advantageousless advantageous
control
stiffness
space requirement
working area
3D-capability
welding depth
invest
FSWmachine
millingmachine
parallel-kinematics
articulatedarm robot
k.o.criterium
Introduction - Relevant machine types for FSW
Not anymore)
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 5 www.kuka.com
automotive
structural component ofthe Panoz Esperante
(source: Friction Stir Link)shipbuilding
railway manufacturing
Shinkansen(HSC Gotland Ferry)
Further applications
Introduction
welding of fuselage of the Eclipse 500 Business Jet
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 6 www.kuka.com
elongationte
nsio
n
FSW joint
base material
• well suited especially for Al-alloys
• high seam quality
• low welding distortion
• no filler metal needed
• intermetallic joints possible
• high process effectivity
• …
source: Airbus
Advantages of the process
Introduction
3-DIMENSIONAL FRICTION STIR WELDING USING A MODIFIED HIGH PAYLOAD ROBOT
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 7 www.kuka.com
Introduction - process notes
• well suited especially for Al-alloys
• high seam qualities achievable
• high welding depths up to 50mm and more
• low welding distortion
• no filler metal needed
• intermetallic joints possible
• no fumes, dust or spatter
• no specially trained staff required
Advantages of the process Disadvantages
• high process forces (depth limitation)
• well disigned clamping technique required
• corrosion behaviour of some weldedstructures (2xxx, 7xxx series)
• License required from TWI (patented: 1991)
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 8 www.kuka.com
supply of KR500 &optimization
experimentals,simulation & evaluation
evaluation &system integration
application
The „RoboFSW“ consortium for evaluation
Capability of a high payload articulated arm robot
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 9 www.kuka.com
Robot• KUKA KR500 MT• modified to realize higher process forces
Welding head• Electrical/hydraulically driven• rotation speed up to 5000 rpm
Process forces• force sensor between flange and welding head• process force controlled without any additional axes
Actual FSW system
Capability of a high payload articulated arm robot
EADS Laboratory
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 10 www.kuka.com
Capability of a high payload articulated arm robot
-4.000
-2.000
0
2.000
4.000
6.000
0 10 20 30 40 50 60 70 80 90 100 110 120 130
time [s]
forc
e [
N]
-4
-2
0
2
4
6
dis
tan
ce [
mm
]
Fx
Fy
Fz
axial toolposition
Force controlled welding mode without additional axes
plunge in phase
welding phase
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 11 www.kuka.com
material: Al6156-T6
thickness: 3.4 mm
joint geometry: butt joint
welding position: horizontal (-Z)
welding direction: -X (to the robot base)
rot. speed: 1800 rpm
welding speed: 240 mm/min
Recent welding sample (without seam tracking system)
Capability of a high payload articulated arm robot
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 12 www.kuka.com
yield strength: 190 N/mm2 (bm: 310 N/mm2)
tensile strength: 270 N/mm2 (bm: 350 N/mm2)
elongation: 4 % (bm: 8 %)
fracture: HAZ
bending test: 180 °
hardness: 75HV0.5 (bm: 130HV0.5)
faults: not detected
cross section: overview
hardness 180°- bending test cross section: root
Results
0
20
40
60
80
100
120
140
ha
rdn
es
s H
V 0
.5Capability of a high payload articulated arm robot
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 13 www.kuka.com
Capability of a high payload articulated arm robot
AW-6056-T6, 5mmbutt joint
process force: 9 kNwelding speed: 600 mm/min
0
20
40
60
80
100
120
140
160
-25 -20 -15 -10 -5 0 5 10 15 20
position [mm]
HV
1
specimen 1
specimen 2
specimen 3
NuggetHAZ HAZ
Linear butt joint
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 14 www.kuka.com
Capability of a high payload articulated arm robot
AW-6056-T6, 5 mmbutt joint
threaded cone shaped tool pinØ3.5 mm to Ø5 mm
Intentional lateral tooldisplacement:-1.5 mm to +1.5 mm
process force: 9 kN
welding speed: 600 mm/min
UTS of 290 MPa with tooldisplacements of ±1 mm
joint surface
specimen ‘+1.2‘ specimen ‘0‘
0
50
100
150
200
250
300
350
0,0 1,0 2,0 3,0 4,0 5,0
elongation [%]
ten
sio
n [
MP
a]
specimen '-1.2'
specimen '-0.9'
specimen '-0.6'
specimen '-0.3'
specimen '0'
specimen +'0.3'
specimen '+0,6'
specimen '+0.9'
specimen '+1.2'
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 15 www.kuka.com
Capability of a high payload articulated arm robot
AW-6061-T6, 1.8 mm, bead-on-plate, convex-concavejoint line; 3D capability
� high process robustness in different welding directions
0
20
40
60
80
100
120
0 10 20 30 40
position [mm]
ha
rdn
ess
[H
V 1
]
hardness +X /C
hardness -X / F
hardness +Y / M
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 16 www.kuka.com
Capability of a high payload articulated arm robot
AW-6061-T6, 1.8 mmbead-on-plateconvex-concave joint linewelding speed: 700 mm/min
angular distortion < 1.5°
3 welding directions:
• radial from the robot base• radial to the robot base• tangential
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 17 www.kuka.com
Capability of a high payload articulated arm robot compared with CNC Machines (Heller and ESAB)
Without Quality difference between the machines:
- modified milling mashine- KUKA articulated arm- esab FSW labor mashineFx
Fz
Mz
FyFx
Fz
Mz
FyFx
Fz
Mz
FyFx
Fz
Mz
Fy
Quelle: Heller
Picture: EADS
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 18 www.kuka.com
0
5
10
15
20
25
30
0 2000 4000 6000 8000 10000 12000 14000
Applied force [N]
Mo
st
loa
de
d e
ng
ine
cu
rre
nt
[A]
direction "+X"
direction "+Y"
direction "-Z"
Results - capability of KUKA robot
Engine currents at different loads
(most loaded engine, medium range)
max. continuouscurrent
���� process forces of up to 10 kN can be achieved in every basic end-
effector orientation.
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 19 www.kuka.com
Results - capability of the robot welds
Casting Material
FSW welded
AlSi10Mg(Fe)
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 20 www.kuka.com
Evaluation of a high payload articulated arm robot
Fx
Fz
Mz
FyFx
Fz
Mz
FyFx
Fz
Mz
FyFx
Fz
Mz
Fy
process forces lead to tool deviations optically controlled lateral tool positioning
Options: compensation of the tool deviation – seam tracking
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 21 www.kuka.com
1. Different machine concepts are suitable for FSW. The
optimal use of each concept is defined by the
requirements of the welding job (e.g. welding depth,
material).
2. High playload articulated arm robots are suited for
welding depths up to 5 mm (and more) because of their
limited engine and structure stresses.
3. The actual FSW system is able to provide process
forces of up to 10 kN in any basic end-effector direction.
Welding in a force controlled mode is possible.
4. The high process forces lead to deviations of the tool
from the programmed path.
Fz(t),
Mz(t)
Fy(t)
Fx(t)
Fz(t),
Mz(t)
Fy(t)
Fx(t)
time
forc
e
Summary
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 22 www.kuka.com
Fz(t),
Mz(t)
Fy(t)
Fx(t)
Fz(t),
Mz(t)
Fy(t)
Fx(t)
time
forc
e
Summary – processing system (for 800 N and more)
© KUKA Roboter GmbH, KTM | 25.08.2009 | Seite 23 www.kuka.com
KUKA Reference Installation