Extrusion International 2-2016

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Extrusion International 2/2016 35
Stagnation is a foreign word to the 200 SIKORA
employees worldwide. Regarding this background,
a new product of groundbreaking innovation was
created, the CENTERWAVE 6000. The core: Several
transceivers, arranged around the circumference of a
tube, sending and receiving continuous frequency
modulated millimeter waves for a non-contact and
µm-precise online measurement of diameter, ovality
and wall thickness for larger plastic tubes during the
extrusion.
During the last years, enormous successes regarding measur-
ing accuracy were achieved by researching metrological ap-
plications with frequencies in the millimeter waves range.
Nevertheless, the results could not yet be used for the coating
thickness measurement of cylindrical products. With the novel,
innovative measuring system, the CENTERWAVE 6000, SIKORA
creates completely new preconditions for the reliable measure-
ment of the nominal size as well as the outer diameter, ovality
and wall thickness of all kinds of extruded DIN-tubes.
Advantages of the new millimeter waves technology
Even without any knowledge of the properties of the extruded
materials and its temperatures, the CENTERWAVE 6000 meas-
ures the outer contour as well as the wall thicknesses simulta-
neously at several places of the circumference, providing a
precision to a previously unknown degree. Layer thicknesses of
multi-layer tubes can also be measured precisely.
Several sensors, so-called transceivers, arranged around the cir-
cumference of a tube, continuously send and receive frequency
modulated millimeter waves. Boundary layers, as for example
each front and back site of a plastic, reflect these waves, which
are detected and demodulated by the receive unit of the re-
garding transceiver. These receive signals contain information
regarding the distance between boundary layers of different ma-
terials. After an algorithmic processing of the receive signals of
each sensor, the requested measuring values are ready for visu-
alization within only a few milliseconds. The values can as well
be used for the control of the different dimensions of a tube in
the extrusion line.
Replacement of conventional technologies
For the development of the technology on the basis of a
CW-millimeter wave chip, the goal of creating a non-contact
measuring device at the extrusion of tubes that is maintenance-
free and durable, was decisive. By independently identifying the
characteristic values of the material, the CENTERWAVE 6000
generates the measuring values with highest precision, without
the need for specifications regarding the material parameters.
The CENTERWAVE 6000 is going to provide highly precise meas-
uring values at different positions of the production line (even in
the hot area) as there are no coupling mediums needed, tem-
peratures are not decisive and no calibrations are necessary
Produckt Spectrum
Two stand-alone gauge heads for different tube diameters from
120 to 400 mm and 250 to 1.000 mm were created. The in-
dustrial PC ECOCONTROL 6000 offers, besides a numeric pres-
entation of the measuring values, also a graphic visualization as
well as extensive trend and statistic data features. The calculation
of virtual measuring values at the position of the extruder allows
the line manager to react quickly to changes. Even with larger
delay times between the position of extrusion and the meas-
urement an effective and fast control of the wall thickness and
especially the elimination of excessive consumed material is
guaranteed.
CENTERWAVE 6000: Key technology for quality
assurance during the extrusion of big tubes
Quality assurance during
the extrusion of big tubes