New system monitors aluminium extrusion billet temperatures

Citation

(2000), "New system monitors aluminium extrusion billet temperatures", Sensor Review, Vol. 20 No. 3. https://doi.org/10.1108/sr.2000.08720cad.003

New system monitors aluminium extrusion billet temperatures

New system monitors aluminium extrusion billet temperatures

Keywords: Aluminium, Temperature sensors

Land Infrared has developed a dedicated system for non-contact measurement of billet temperature profiles in aluminium extrusion (see Plate 3).

Faster and more accurate than conventional thermocouples, the new aluminium billet thermometer system (ABTS) is a simple, low-cost means of monitoring temperature profiles (or "tapers") continuously, and without interrupting production.

Plate 3Land Infrared has developed a dedicated system for non-contact measurement of billet temperature profiles in aluminium extrusion

By controlling the taper along the length of the billet, extruders can compensate for the heat generated by friction in the die to produce a consistent optimum temperature at the point of extrusion. Benefits include increased efficiency, better product quality and reduced die wear.

Until now, temperatures have usually been monitored by prodder thermocouples that make contact with the billet at a limited number of fixed points - but thermocouples are slow to respond, inaccurate if metal builds up on the tips, costly and time-consuming to replace.

By contrast, Land's non-contact ABTS simply views each billet as it passes from heater to loader, transmitting the temperature - typically between 300 and 600°C - as a 4 to 20mA analog signal.

The system's 20 millisecond response time is sufficient to keep pace with the speed of the billet, giving a measurement accuracy of better than ±5°C on 6000 series alloys.

Robust and simple in design, the ABTS has three component parts. The optic head is mounted 15 to 20mm from the billet surface and linked by a fibre optics light guide to the thermometer and signal processor, which are located in a convenient position away from the heat of the extrusion line.

The optic head incorporates the latest version of Land's unique emissivity enhancer, which minimises measurement inaccuracies caused by variations in billet surface finish such as weathering, paint markings and scratches.

For even greater efficiency, the aluminium billet thermometer system can be integrated with Land Infrared's AETS thermometer, which monitors extrusion temperature at the die exit.

Enquiries to: Tom McDougall, Land Infrared, Dronfield S18 1DJ, England. Tel: +44 (0)1246 417691; Fax: +44 (0)1246 410585; Email: infrared@landinst.com URL: http://www.landinst.com