TPT September 2012

68 / 156

Technology News
66 September 2012
CNN camera for 100 per cent
surface inspection at high speed
QUALITY control in high-speed
production processes poses a challenge
in many industrial areas such as
electronics, medical or automotive.
Tubes, wires or rods produced for
medical, telecommunications or
aerospace applications, for instance,
have to comply with high quality
standards. Here, immaculate surfaces
are required for functional or aesthetic
reasons and have to be achieved at very
high production rates. Fraunhofer IPM
has developed an inline measurement
system that guarantees 100 per cent
quality control of surfaces at high
production speeds.
Signal processing and camera speed
are the bottlenecks of a 100 per cent
quality control in such processes. Even
today, many manufacturers of high-tech
materials and components rely on visual
inspection at the end of the production
chain. Defects, which result from used-
up or damaged tools, for instance, may
concern every single work piece of a
whole production batch – which boosts
the reject rate. In this case, an effective
inline-control of production processes is
necessary to identify errors immediately
after they occur in order to be able to
fix the problem in due course. Random
defects such as scratches or disposals
may be reason enough for the customer
to reject the complete delivery. A 100 per
cent surface inspection makes it possible
for manufacturers of wires, tubes or steel
sheet to identify and document errors
and thus reduce the error rate in further
production steps.
The German Fraunhofer IPM, an
institute for applied research with a focus
on optical measurement techniques,
has developed an inline measurement
system, which guarantees 100 per
cent quality control of surfaces at high
production speeds. FlexFormCNN is
the first image based system capable
of completely surveying surfaces at
production speeds in the order of 10m
per second. The inline inspection system
uses pixel-parallel image processing
based on cellular neural networks
(CNN), which allow image evaluation up
to 10kHz.
A recent implementation of the
technology is an inspection system for
wire production, which has just been put
into operation. Typical surface defects
in wire production processes are cross
dents, drawing marks and so-called
chatter marks. Wires with diameters
from 0.4 to 2mm typically show such
defects ranging from a few millimetres
to 50m. Ordinary image processing
systems miss these defects when
inspecting the fast-moving wire surface.
In FlexFormCNN, Fraunhofer IPM has
developed an inline image processing
system which is able to recognise a
50m scratch on a wire whizzing by at
speeds of 10m/s and evaluate it at the
same time. This is possible thanks to
camera-internal pixel-parallel image
processing and a specially adapted
lighting system.
The image processing system relies on
a CNN camera in which each pixel has its
own processor. The camera processes
up to 10,000 images per second at a
176×144 pixel resolution. To inspect
moving surfaces, an image processing
system’s lens must fulfil many criteria:
first, the defects must be shown at such
high contrast and so brightly that the
exposure time is short enough to prevent
blurring. Secondly, both the depth of
field and the optical resolution must be
sufficient for the smallest relevant defects
to be shown sharply over the whole
measurement area. Thirdly, especially
on uneven metallic surfaces, disturbing
reflections must be prevented so that the
light intensity is uniformly distributed on
the object surface. Thus, the right lighting
is crucial for processing images of
moving objects. To guarantee sufficient
light intensity on a defined focal area,
special optics using dark field illumination
and high-power LEDs with a pulse length
of 10 µsec are employed.
Fraunhofer IPM – Germany
Website:
Prefabricated Piping
Over 250,000MT of Prefabricated Piping Experience and
10,000MT of Super Critical P91 and WB36 Piping experience
Annual Capacity - 34000MT and
Manufacturing Facility - 100,000 Sq. Ft.
Induction Bending
Capability – Thickness: Up to 120mm, Diameter: 2” - 48”,
Bend Radius: 76mm - 6500mm
Pipe Fittings
2400 MT Annual Capacity and of Capability to manufacture
up to a wall thickness of 120mm and 52” in diameter
Engineering Services
Dedicated team of over 30 engineers with a
combined experience of more than 160 years
ISO 9001:2008
ISO 14001:2004
OHSAS 18001:2007
Pressure Equipment Directive (PED)
ASME "S" & "PP" Stamps
NABL Accredited Laboratory
Approved by NPCIL
DEE DEVELOPMENT
ENGINEERS LIMITED
Pioneers of Pre-Fabricated
Piping Systems
Corporate Office / Manufacturing Facility -
Plot No 5327 & 6412 Prithla - Tatarpur Road,
Tatarpur Distt. Palwal, Haryana – 121102, India
Email:
Phone: +91-1275-248200/260
US Marketing Office: DDE Piping Systems LLC
2 Ravinia Drive, Suite 500, Atlanta - GA
Email:
Phone: +1-6788557069