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4.1.4.2. Scanners
No matter how a scanner is designed,
its structural shape is such that the transducer does not
touch the surface of the product. Sensors can be adjusted
to optimise the focus.
Possible line configurations are covered with 2 basic methods
for mounting UMAC scanners:
a) Submerged operation: The
so-called A-scanners are completely immersed: they can be
directly "sunk" into available cooling troughs.
There is no need for any cable guide: they are completely
contact-free.
Such scanners are available for small cables (= 1 mm Ø)
and for heavy cables with OD up to 200 mm.
They can be also mounted directly into the vacuum calibration
tank following the extruder. A-scanners are extremely reliable
due to the simplicity of their corrosion-free design.
b) With autonomous water supply:
R-scanners are used where submerged
operation is impossible or difficult (e.g. if measurement
has to take place between two cooling sections or if there
is not enough available space for submerged operation). A
closed, circular chamber containing the ultrasonic transducers
is filled with water from an external supply. Cable guides
at the entry and exit points seal the ring and centre the
measured cable. A collecting basin for the water leaking through
the guides has to be provided.
4.1.4.3. High Test Coverage
The ultrasonic transducers are sampled
at a high frequency, i.e. the measurement process "rotates"
in a tight spiral around the running cable.
Example:
A 4-point scanner provides 300 measurement revolutions per
second at a sampling frequency of 1200/second. If the cable
is running at 100 m/min., the length of twist of the measurement
spiral is of the order of 5 mm. This means that the thickness
of the sheathing is tested nearly without any gap.
UMAC®
Scanner overview
 
4, 6, 8 Point Scanner with inlet for its own water supply |
|
Miniscanner for mounting in the existing cooling trough |
|
A-Scanner with its own Waterbath for attachment to the
start of the cooling trough. (with adjustable input and
output membrane seal) |
 |
|
 |
|
 |
| A-Scanner for submerged
operation |
Submerged or with own water supply
A-Scanner for submerged operation |
R-Scanner with its own water
supply inlet mounted between 2 cooling troughs |
4.1.4.4. Examples of Applications
The coating process used to lay the
coaxial sheathing during production may undergo some deviation
from a concentric distribution. Customers using automated
cable strippers require cables with especially narrow tolerances.
a) Solution
Continuous monitoring of the PVC, PE
and PU sheathing's centering of semi-finished coax cables
based on sheathing wall thickness measurement with 4 ultrasonic
sensors offset at 90°.
Scanner in operation |
UMAC®-ECOWALL |
b) Field of application
| Wall thickness range: |
0.4 - 1.5 mm |
| Cable OD Ø: |
3.2 - 12.5 mm |
| Line speed: |
10 - 80 m/min. |
c) Advantages
- Measurement remains accurate within
±0.03 mm, even with non-conducting braid or tape under
the sheath.
- Seamless documentation of the eccentricity.
- Measurement on warm products.
- Pay back < 1 year.
- Reduction of scrap, material consumption reduction
4.1.4.5. Example with CAT 5 Datacable
The extrusion of the sheathing with
expensive material must be controlled exactly. Reason is the
high material cost as well as the demand for quality documentation.
UTP cables (Unshielded twisted pairs) where there is no metallic
subconstruction available represent a typical Ultrasonic application.
a) Solution
A 4 point A-Scanner is flanged directly
on to the start of the telescopic cooling trough. It is in
its own water bath with adjustable input seal.
b) Field of application
LAN CAT 5 cable
| OD: |
< 10 mm |
| Wall: |
0.3 - 1 mm |
c) Advantage
See point 4.1.4.4
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