US 11,885,615 B2
Method for thickness measurements of a work item in a rolling mill
Jarl Sobel, Bagarmossen (SE); and Martin Haldin, Västerås (SE)
Assigned to ABB Schweiz AG, Baden (CH)
Filed by ABB Schweiz AG, Baden (CH)
Filed on Mar. 11, 2021, as Appl. No. 17/198,348.
Claims priority of application No. 20170575 (EP), filed on Apr. 21, 2020.
Prior Publication US 2021/0325167 A1, Oct. 21, 2021
Int. Cl. G01B 7/06 (2006.01); B21B 38/04 (2006.01)
CPC G01B 7/107 (2013.01) [B21B 38/04 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method for determining a present thickness of a work item while being processed in a rolling mill, the method comprising:
acquiring a data signal reflecting a time dependence of an eddy current decay in the work item caused by an applied pulsed magnetic field,
determining a thickness parameter value based on the data signal, the thickness parameter value being determined from samples in the data signal, the thickness parameter value being dependent on a ratio between a thickness of the work item and a resistivity of the work item,
computing a ratio between a reference thickness value of the work item and the thickness parameter value to thereby provide an instantaneous resistivity value,
determining a mean resistivity value based on the instantaneous resistivity value, and
providing an output signal based on the mean resistivity of the work item and the thickness parameter value, the output signal being indicative of the present thickness of the work item.