S Und S Essen 2009

© 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


Introduction

shoulder

pin

plunging in

friction heatis generated

welling

D

welding retractingProcess description

2 mm

NuggetTMAZHAZ


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


�� 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)


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


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


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)


supply of KR500 &optimization

experimentals,simulation & evaluation

evaluation &system integration

application

The „RoboFSW“ consortium for evaluation

Capability of a high payload articulated arm robot


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


EADS Laboratory



-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


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)



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



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



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'



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



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


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


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.


Results - capability of the robot welds

Casting Material

FSW welded

AlSi10Mg(Fe)


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


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


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 Reference Installation

S Und S Essen 2009

Automotive

Transcript of S Und S Essen 2009