I used this method while employed with GE in the late 90's. Basically the system calibrates on an in-service part using the pitch-catch method. 2 sets of transducers are used. 1 set sends a pitch-catch through the thicknes in a v path to measure the transit time and calculate the velocity. The other set sends a surface wave in a pitch catch configuration. I don't exactly remember the purpose, but both setsd are used for velocity/thickness/transit time determinations. The entire purpose of the system is to measure the thickness or loss of thickness in cast parts of unknown velocity. I think the system worked quite well and we verified constantly by using spring calipers through the manhole to measure the thickness mechanically.
Hope this helps. I think the system was made by Krautkramer. ----------- Start Original Message ----------- : Has any one heard of the Auto V method for Dryer Rolls? ------------ End Original Message ------------
Thickness measurements by ultrasound are based on time measurements. The thickness is calculated with the measured time-of-flight of the pulse and the known sound velocity of the material. Problems arise when the velocity is not known or is changing at different locations on the test object. Cast materials, i.e. cast iron from which dryer rollers for the paper industry are made, show changing sound velocity. The Auto-V process overcomes this problem by determining the velocity on the location where the thickness has to be tested, calibrating the thickness gauge automatically to this velocity and determining the material thickness using the auto-calibrated velocity. For more information see the web page of GE Inspection Technologies (Thickness Gauge DMS 2)or contact a local GE IT dealer. http://www.geinspectiontechnologies.com/en/products/ut/thickness_guages/dms2.html
Best regards Udo Schlengermann GE Inspection Technologies GmbH Huerth, Germany
----------- Start Original Message ----------- : Has any one heard of the Auto V method for Dryer Rolls? ------------ End Original Message ------------