Accurate temperature detection of moving wires

June 2013 — In steel wire and rod production, process temperatures have a significant effect on the quality and physical properties of the resulting product. The objective is to maintain constant temperatures during heat treatment. Pyrometers are ideal for this application, because they continuously monitor temperatures during running operations without contact. A wire or rod will often move laterally, perpendicular to the axial direction. A swaying or oscillating target object, however, poses a challenge to the measurement. When using a standard pyrometer which can focus on a round target spot, there is the risk of not always capturing the wire as it might move outside of the target. To solve this problem, pyrometers are commonly equipped with oscillating mirrors – either integrated or mounted as an auxiliary device. Such an oscillating mirror has the function of cyclically deflecting the radiation emitted from the target. The disadvantage of this technique is that it involves mechanical moving parts. To capture such a small object, the pyrometer is often positioned just a few cm from the target. Thus, the instrument is exposed to high ambient temperatures as well as dust and steam. The conditions in a harsh industrial environment reduce the service life of the oscillating mirror and increase the amount of maintenance required. Based on the new “Cella Temp PA” series, Keller MSR has developed a new two-colour (ratio) pyrometer which features a rectangular measurement area rather than a circular target spot. With this technique, the target object may be smaller than the measurement area. Regardless of where the wire or rod moves within this rectangular measurement area, the pyrometer will always capture the target and detect its precise temperature. Changing wire diameters will not have a bearing on the accuracy of the measurement. When excessive dust or oil settle on the optics, an integrated feature signals that the lens should be cleaned. The rectangular measurement area is a feature of the optics and is thus achieved without moving parts. With through-the-lens sighting, focusable precision optics, and the rectangular measurement area within the field of view, the pyrometer can be properly focused on the wire. The pyrometer is supplied with one of four different lenses – depending on the amount of lateral wire movement and the wire diameter of the specific application. A large-sized LED display on the pyrometer’s back panel makes it easy to see the temperature reading during installation and running operations. The temperature data can be viewed even at a distance of up to 10 meters.

Keller HCW GmbH – Division MSR
Phone: + 49 5451 85320

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