A Methodology for Temperature Correction When Using Two-Color Pyrometers - Compensation for Surface Topography and Material
Journal article, 2014
In this investigation, the applicability of the twocolor
pyrometer technique for temperature measurements in
dry hard turning of AISI 52100 steel was studied, where both
machined surfaces as well as cutting tools were considered.
The impacts of differing hard turned surface topography on
the two-color pyrometer readings was studied by conducting
temperaturemeasurements on reference samples created using
cutting tools with different degrees of tool flank wear. In order to conduct measurements in a controlled environment, a specially designed furnace was developed in which the samples were heated step-wise up to 1,000 °C in a protective atmosphere. At each testing temperature, the temperatures measured by the two-color pyrometer were compared with temperatures recorded by thermocouples. For all materials and surfaces as studied here, the two-color pyrometer generally recorded significantly lower temperatures than the thermocouples;for the hard turned surfaces, depending on the surface topography, the temperatures were as much as ~20 % lower and for the CBN cutting tools, ~13 % lower. To be able to use the two-color pyrometer technique for temperature measurements in hard turning of AISI 52100 steel, a linear approximation function was determined resulting in three unique equations, one for each of the studied materials and surfaces.
By using the developed approximation function, the measured
cutting temperatures can be adjusted to compensate for differing materials or surface topographies for comparable machining conditions. Even though the proposed equations are
unique for the hard turning conditions as studied here, the
proposed methodology can be applied to determine the temperature compensation required for other surface topographies, as well as other materials.