Infrared sensors monitor steel temperatures in rolling mill

At its Swinden Technology Centre in Rotherham, Corus has an experimental rolling mill that is approximately one-eighth the size of a conventional full-size mill. This is being upgraded with four non-contact, infrared temperature sensors from Micro-Epsilon to measure temperatures at various positions along the process line. This will enable Corus to make better, more informed decisions with respect to cooling methods for different steel strip products.

Four Micro-Epsilon thermoMETER CTM2 temperature sensors will be positioned at various points in the rolling and cooling process. Two of these sensors are already in position and have been used to measure temperatures on the high-temperature rolling side. The other two sensors will be located on the cooling conveyor, one at the start and another low-temperature version of the sensor at the end of the cooling system. The process temperatures on the rolling side vary from 850 to 1100degC, while temperatures on the cooling side are around 600degC. The sensors located on the rolling mill housing are positioned so that they point straight down into the centre of a steel block from a distance of around 400mm.

Garry Beard, Development Engineer at Corus Swinden Technology Centre, states: "The scale model rolling mill is being developed to test different cooling regimes for Corus' steel strip products. In early 2009, we decided that we needed some new non-contact temperature sensors on the rolling mill. These sensors needed to be small, robust and accurate. At the time, we were using temperature sensors that were relatively large in comparison to the Micro-Epsilon ones. We also wanted dedicated sensors that we could fix to the rolling mill."

Size, accuracy and repeatability

After evaluating Micro-Epsilon's range of non-contact infrared temperature sensors, Beard selected the thermoMETER CTM2 version. He comments: "The compact size, accuracy and repeatability of the sensors swayed our decision. Micro-Epsilon was also happy to lend us a trial sensor to enable our engineers to try it out on the rolling mill. We also had an onsite demonstration of the sensor and excellent technical support from Micro-Epsilon when we needed it."

Temperature measurement data collected by the four sensors is fed into the rolling mill's software program, where it is used to model and simulate the different cooling methods for the steel strip. Beard adds: "The sensors on the rolling stand have been installed for more than eight months now and are performing without any problems. As soon as our instrumentation team set up the sensors and controllers, it all seemed to work very well, with data being fed from the Micro-Epsilon controller to our own data logger. In fact, we are so confident in Micro-Epsilon's products that we have just ordered four similar sensors for use in plant process monitoring."

Micro-Epsilon's thermoMETER CTM2 range of infrared temperature sensors measure process temperatures from 250 up to 1600degC and so are appropriate for use with metals, metal oxides, ceramics and composites. The sensors benefit from double-precision laser sighting and a 40:1 or 75:1 optical resolution. Sensor response times are from 1ms. The sensor weighs just 40g and the controller 420g.

The thermoMETER CT laser M1/M2 can be used in ambient temperatures up to 100degC without any cooling required and has an automatic laser switch off at 50degC. The sensor measures at very short wavelengths (1.0-1.6um), which minimises temperature measurement errors on surfaces with either low or unknown emissivity.

Various accessories are available for the CTM1/M2 range to protect the sensor in harsh operating environments. These include air purging accessories, K or J type thermocouples outputs and a range of integrated digital communications interfaces - including Profibus DP, CANopen, USB, RS232, RS485 and Ethernet.

Follow the link for more information about Micro-Epsilon's thermoMETER range of non-contact temperature sensors.