Quality Management

Temperature of moving wires

September 2013 — Pyrometers are ideal for measuring the temperature in wire and rod production. They monitor the temperature of the passing wires from a safety distance during the running operations without contact. The difficulty of the measurement is that the position of the wire or rod is not fixed. They will often move laterally, perpendicular to the axial direction.

When using a one-colour 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. Also changing wire diameters will affect the accuracy of the measurement when using a standard pyrometer: Measurement using a common portable pyrometer is therefore not really practicable. Aiming a hand-held pyrometer at a small moving object such as a thin wire is difficult. Holding the pyrometer steady enough to ensure that the wire remains within the target spot at all times is nearly impossible.

To meet the challenge of this application, the engineers at Keller MSR have come up with an innovative solution: the new “Cella Wire PT 143”. This pyrometer features a unique rectangular measurement area. Because this feature is part of the optical system, it is achieved without moving parts. The pyrometer is based on the two-colour or ratio method. 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.

The rectangular measurement area – rather than the common circular spot – makes manual targeting so much easier. The Cella Wire PT 143 captures the wire, even when it sways or when its diameter varies. It is supplied with through-the-lens, parallax-free sighting. The wide field of view makes it easy to focus on the target object. The rectangle in the viewfinder indicates the exact position and size of the measured target spot.

The pyrometer is infinitely adjustable to ensure superior precision across a wide focusing range from 0.4m to infinity. The ocular features a widened interpupillary distance, making it suitable for users who wear glasses or a helmet. As a two-colour pyrometer Cella Wire PT 143 produces very reliable temperature data even when dust, steam or a dirty lens might significantly obstruct the instrument’s line of sight.

The Cella Wire PT 143 features signal attenuation monitoring (SAM), a function which monitors if the amount of infrared energy detected is sufficient for a reliable temperature measurement. A traffic light status indicator is integrated in the viewfinder. It lets the user know when emitted infrared energy does not completely reach the sensor due to the pyrometer lens is dirty, the amount of signal attenuation caused by dust, steam and smoke is too high, the diameter of the wire is too small or the distance is to the target is too large. If the detected energy is reaching a crucial level the SAM avid to display a wrong measuring value.

The pyrometer is extremely simple to operate. Thanks to automatic temperature detection (ATD), the Cella Wire PT 143 starts measuring as soon as you switch it on and point it at the target. After a few seconds the measurement stops automatically. An audible alarm indicates the end of the measurement. The pyrometer shows the correct temperature reading at the display. For prolonged temperature data logging, the Cella Wire PT 143 can be mounted on a tripod and the data to can be transmitted to a PC by the USB interface The “Cella Mevis” software, which is supplied with the pyrometer, provides online graphical display and enables data analysis and archiving of the temperature value and time. “Cella Cast PT 143” comprises different models for temperatures ranging from 600°C to 3000°C. The pyrometer is supplied with one of four available lenses. The target size and distance you require will determine which lens is most suitable for your application for wire diameter from 2mm. By mounting an additional lens the pyrometer models can capture target spots as small as diameter 0.5mm.

Keller MSR Infrared Temperature Solutions
Carl-Keller-Strasse 2-10, 49479 Ibbenbüren/Germany
Phone: +49 5451 85-320
e-mail: albert.book@keller-hcw.de

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