The roundness of rollers is necessary in the production of tapes and foils. During production, speeds of up to 2700 m/min can be achieved and this can lead to an increased vibration tendency in the roller stands. A small micron range irregularity in the rolling contour can lead to cross-grooves on the rolled material and reduce the quality of the product. For quality assurance a high-precision roundness measuring system for rollers is required.
The multiNCDT measurement systems, from Micro-Epsilon and available from Bestech Australia , are suitable to measure roundness or ovality. They are eddy-current displacement sensors which measure the surface contour of the roller. With computer support, the angular position of roundness errors and the accumulation and periodicity of circularity errors can be documented.
Eddy currents are generated in the target material using a coil and the impedance variation results in a linear electrical signal proportional to the distance of the target from the sensor. The sensor has a measuring range of 1000µm and accuracy of below 0.2% non-linearity. Resolution is down to 1µm and a bandwidth of 10kHz is used.
This means that the eddy-current sensor makes it easy to measure reliably and accurately, without contact. They are also non-wearing and require minimal maintenance. Any obstructions in the measuring gap, such as dirt, dust, moisture, oil and dielectric materials are not detected.