presentation WAAM university of bath.pdf

wire arc welding process

1. Euspen2017 -University of Bath Department of
Mechanical Engineering
Fangda Xu, DrVimal Dhokia, Prof. Stephen T. Newman
Advanced Manufacturing Processes & Systems
University of Bath
RAWFEED Partners
Process Control For Wire-Arc Additive Manufacturing

2. Euspen2017 -University of Bath Department of
Mechanical Engineering
Process Control For Wire-Arc Additive Manufacturing
Fangda Xu
Vimal Dhokia
Stephen Newman
Andy Henstridge
Steve Porter
David Steer
Kelvin Hamilton
Johnny van der Zwaag
Jan Willem Gunnink
Anthony McAndrew
Paul Colgrove
Jon Pratt
Stewart Williams
RAWFEED Partners

3. Euspen2017 -University of Bath
Content
1Concept of WAAM
2Challenges to WAAM
3Rolling Assisted Wire Feed Direct Deposition
4Realisation of Multi-Sensor System
5Conclusions

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1Concept of WAAM
•WAAMis a arc-based Additive Manufacturing technique.
•WAAMcan build large part with low cost.
•WAAM can achieve high energy efficiency.
Schematic of WAAM process WAAM depositing process

5. Euspen2017 -University of Bath
1Concept of WAAM
Source: http://www.norsktitanium.com/

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2Challenges to WAAM
Distortion & Residual Stress are an challenges in WAAM
Shrinkage and uneven cooling rate are the main reasons
for distortion and residual stress
Too many factors are involved in the WAAM process, such
as welding voltage, welding current, feeding speed,
ambient temperature, protecting gas flow rate, etc.
Still lack of systematic metrology method for WAAM
Aeroplane near net-shape part
WAAM produced part tilts up due to the residual stress
~40mm

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3RAWFEED -Concept
•ROLLING every layer
after it was deposited to
improve the microstructure
and the mechanical property
of the material
Video Source: Cranfield University
•This method has been
proved to be effectively
reduced 30% ~ 50%
distortion.
Ref: Colegrove, P. a., et al.(2013).
Journal of Materials Processing

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3RAWFEED -Demo

9. 3RAWFEED -Platform

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4Multi-Sensor System –Requirements
Real-time monitoring system to monitor:
•Shape to provide feedback for rolling system
•Heat to avoid excess heat input/output which may
cause distortion
•Oxygen level to prevent part from oxidation

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4Multi-Sensor Framework –Aims
Factors monitored:
1 Oxygen Level2 Gas Flow Rate3 Current 4 Voltage 5 Temperature
6 Profile 7 Wire Feed Speed (WFS) 8 Welder Travel speed
Deformation
Shape
Oxidation Irregular bead

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4Multi-Sensor Framework –System Topology

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4Realization of Multi-sensor System

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Multi-Sensor System –Laser Scanner4

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Multi-Sensor System –Laser Scanner Result4

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4Voltage Sensor
Sampling Rate: 5Hz
Voltage Signal fluctuated within a small range.
The reason is under invertigation.
It might be due to the continuous periodic metal wire melting and dropping 0 20 40 60 80 100 120 140
22
24
26
28
30
32
34
Voltage (V)
Time (s)
Raw Voltage
0.01 Hz Low Pass fft filter of C
arc extinguished 0 20 40 60 80 100 120
27.5
28.0
28.5
29.0
29.5
30.0
30.5
31.0
31.5
Voltage (V)
Time
Raw Voltage -20 0 20 40 60 80 100 120 140
20
22
24
26
28
30
32
34
Voltage(V)
Time(s)
Raw Voltage
Voltage Sensor Result
Another two voltage result

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4Current Sensor0 20 40 60 80 100 120 140
-400
-300
-200
-100
0
100
200
300
Current (A)
Time (s)
Raw Current
arc extinguished
The signal data distribution roughly conforms to the Normal Distribution,
and the noise might be able to be eliminated by KilmanFilter
Approximate Trend (About 220
V) 0 20 40 60 80 100 120 140
-50
0
50
100
150
200
250


Current (A)
Time (s)
Kalman Filtered Current
Kalman Filtered Current

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4Average Height Variation along Y axis

19. Euspen2017 -University of Bath
4Realization of the System –Structure
Heat Monitoring Sub-system
Infrared Sensor
Arc Voltage/Current Sensor
Bead Geometry Control Sub-system
Laser Profilometer
Wire Feed Speed Sensor
Torch Travelling Speed
Environment Monitoring Sub-system
Oxygen Concentration Sensor
Shielding Gas Flow Sensor

20. Euspen2017 -University of Bath
5Conclusions
•The main problems in the WAAM process have been analysed and
a novel integrated monitoring solution proposed.
•A multi-sensor system has been built to monitor the WAAM
process.
•The specified system shows that for a WAAM machine with an
integrated rolling process to be monitored and controlled, a wide
range of sensors needs to be configured and used.

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Any Questions?