Systems for rail geometry measurement
Stringent rail geometry quality requirements require their measurement at various stages of their manufacturing process. Rail geometry quality assurance calls for their measurement at least at two stages, marked 1 and 2 in the picture below.
The first rail geometry measurement system in the finishing line is used for checking rail flatness, straightness, twist, and its transverse section dimensions. Laser triangulation probes and laser micrometers are mounted on a rigid steel structure, consisting of separate measurement beams and a measurement frame, ensuring high dimensional, long term stability of readings. Rails are carefully guided as they travel along the system, however, the rail guiding does not affect the rail profile in any way. After collecting measurement data the system processes it to obtain the true rail profile. This profile is then analysed according to the requirements of the pertinent standard.
A number of rails may require repair of their geometrical defects. Therefore, close integration of the measurement system with the gag press has been needed. Measurement system and the gag press are placed close to each other, so that the gag press operator does not have to lose much time to verify the rail repair effect. The gag press operator has all information needed to repair the rails. The final rail measurement results - after its successful repair - may be used to confirm the required rail quality.
Rail measurement philosphy acquired by GRAW consists in collecting the detailed rail geometry data, developing the true rail profile model based on the measurement data, and further - rail geometry quality assessment aqccording to the user specified standards. Therefore, the rail quality standards used do anot affect in any way the rail measurement technology, as they influence only the way in which the rail true profile is analysed - including rail ends geometry measured while the rail travels along the prodduction line. The important features of the measurement systems developed by GRAW are their built-in diagnostic functions, ease of calibration, high accuracy and repeatability as well as the excellent long term stability. Many years' long operation of the rail measurement systems developed by GRAW have provided good examples of the accuracy and repeatability of measurements like for the rail running surface (front end, body, back end) or for the rail side surface (front end, body, back end).