A handheld profile measurement system for high accurate wear measurement of railway wheels

Wear of railway wheels - especially for engines - has to be checked in regular intervals. For this check, some key dimensions of the cross section of the running surface like flange height, flange gradient or flange thickness have to be measured with accuracies in the range of 0.1 mm. State of the art is either the use of mechanical gauges or stationary optical measurement systems where the carriage has to be driven to a maintenance stand in a servicing centre. We present a new technique for building up a small portable hand held measurement system, which allows to perform data acquisition and dimension evaluation in an easy and convenient way by simply freehand scanning the interesting section of the wheel. The technique is based on the laser light sectioning technique. A special setup with multiple laser lines in combination with appropriate algorithms allows to correct errors due to inaccurate sensor slant as well as fusion of measurement data to generate a cross section of the wheel out from multiple partial measurements.