Immersion inspection systems for production and laboratory
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Systems
from 0.3 to over 20 metres long
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2
to 10 axis configuration
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Contour
following systems for complex curves
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Multi
probe systems for high throughput
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PC
based high gain - ultra low noise ultrasonics
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C scan and B scan,
thickness mapping, volume scan
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High
speed automated production units
A wide range of immersion systems is available for inspection
of discs, bars, forgings and fabrications - typical examples are shown below.
Six
axis system for inspection of forged discs and other roto-symmetrical parts to
Rolls Royce, Pratt & Whitney, GE and similar specifications. A full contour
following capability is incorporated, with special software for simple
implementation of daily calibration routines.
This
is a simplified version of the system shown above - this time with 4 motorised
axes (X, Y, Z and rotate) and a manual probe manipulator. The turntable has a
raise / lower mechanism for ease of loading. This particular system has special
software for processing C scan images generated from multiple gates, to
highlight "real" defects from other indications caused by
surface blisters, for example.
This is one of many systems installed at Rolls Royce for
inspection of titanium alloy fan blades during the production process. The tests
carried out include inspection of the diffusion bonded interfaces at different
stages, automated thickness mapping of the blades and bond inspection at the
blade root. The particular machine shown above is a 4 axis system for thickness
mapping, which uses a mechanical contact follower. Unlike machines supplied for
inspection at earlier stages, programmed non contact following is not necessary
for this application.
General
purpose 7 axis system with X, Y, and Z linear axes, A and B probe manipulator
axes, turntable and roller drive units. This unit was designed for a testing
laboratory, but is equally suited to production applications. Optionally, it can
be fitted with a Z axis yoke and squirters, for through transmission inspection
of composite panels held vertically and scanned in an X-Z mode.
This system is installed at TWI, Port Talbot. You can get more
information on TWI's general activities at http://www.twi.co.uk
, or more specific information about the Port Talbot site on: http://www.twi.co.uk/j32k/unprotected/band_1/ndt_index.html
Large system for inspection of titanium alloy plate
destined for engine fan blades. The system uses
multi-channel ultrasonics and focussed probes for testing to stringent
defect standards - typically 0.8mm FBH equivalent. The immersion tank is separated into two halves by a removable
plate. The water can be pumped from one side of the tank to the other in a few
seconds, to allow one side or the tank to be loaded whilst the other side is
scanning.
6 axis system for production inspection of composite
propeller blades, including full contour following and RF acquisition with
real time B scan imaging. A dual axis "goniometric" manipulator is
used, with the part shape programmed by a "teach and learn" procedure.
In this case an additional follower can be used to compensate for small local
variations in the surface profile.
Some immersion testing applications require more specialised
functions to facilitate the inspection of parts having an unpredictable shape.
For example, in some some systems used for the inspection of SPFDB (superplastically
formed - diffusion bonded) components, the scanning system is programmed to do a
coarse scan over each part in order to measure the actual surface profile. This
information is then used to automatically modify the main scanning program to
suit the shape of each component. One of these systems is shown below.
 
Many of these systems require dual axis probe manipulators for
programmed contour following - these have to be reliable for long periods with
more or less continuous immersion. One such manipulator is shown below:
 This
typical manipulator includes double sealed motors and a Harmonic Drive TM
zero-backlash gearbox. It is manufactured from machined stainless steel, or in
some cases titanium alloy for light weight. Manipulators can be configured for
tilt / tilt in two orthogonal axes, or tilt/swivel according to the requirements
of each system. Where necessary, more than 360 degrees of angular movement is
possible.
In other multi-channel systems, the surface profile of plates
is measured ultrasonically and the angle of the array probe is adjusted in
"real time". Also slight variations in plate thickness are
accommodated by measuring the actual thickness during the scan and dynamically
changing the monitor gate width to maintain a preset "near surface"
and "far surface" resolution.
These pictures show a large tank installation, one of three on
this site, for inspection of aerospace aluminium alloy plate up to 200mm thick.
The systems incorporate 6 scanning axes and a 2 axis
mechanical scriber which is used to mark the position of confirmed defects.
Other features include detection of plate size and
orientation, automatic following of random contours to maintain probe normality,
8 channel ultrasonics, "elastic" gates which follow the measured
thickness of the plates and continuous back wall monitoring.
This
is a 5 axis multi channel system for inspection of plate material. It is
designed for use with a motorised immersion tank which can be driven outside the
scanning unit for loading and unloading operations.
The scanning bridge and tank motions are interlocked so that
there is no risk of collision if, for example the operator tries to move the
tank when the Z axis manipulator is lowered. In addition, there is a collision
protection ring around the probe array to avoid collision damage when scanning,
if an incorrect scan plan is attempted.
System features
Mechanical
Systems with 2 to 10 axes
Any combination of linear, manipulator,
turntable, chuck rotate and bar rotate axes
DC or stepper motor drive
Rack and pinion, ballscrew or belt
drive
High quality linear bearings (NSK type)
giving long life under arduous conditions
Precision optical encoders - linear
scale (Renishaw type) available on long linear axes
Resolution down to 2um, repeatability
down to 5um (dependent on system type and application)
All immersed components are stainless
steel
or titanium alloy
Pulse echo and through transmission
systems
- simultaneous acquisition of data
Precision manipulators - gimbal/gimbal,
gimbal/rotate and goniometric
Ultrasonics
Fully integrated PC-based ultrasonics,
data acquisition and motion control
Fully production hardened for noise
immunity
Exceptional S/N ratio and near surface
resolution
Digital A scan display
with refresh rate >60Hz
Up to 8 independent gates per channel -
amplitude, time of flight and phase monitoring
Single and multi-channel operation
Multi-channel, multi-gate data
acquisition at PRF’s up to 20kHz. Higher PRF available with 2 or more
pulser receivers
Frequency from <0.5MHz to >50MHz
Software
Windows 2000 with simple operation using pull down menus
A, B and C scan display in real time
Storage, recall and automatic setup for
all test parameters
Programmed gate changes and auto gate
setting
Display of images from multiple gates
simultaneously
Full RF data acquisition and processing
On screen measurement and analysis
Multi axis motion control for complex
shapes
Generation
of scan profiles from CATIA files
Options for auto sensing of part shape
and self teaching capability
Interfaces to factory network and
mainframe computers
Custom software for special user
requirements
Virtual
Private Network (VPN) available for remote monitoring and support.
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