US 11,685,984 B2
Method for controlling a coating weight uniformity in industrial galvanizing lines
Michel Dubois, Boncelles (BE); and Giuseppe Callegari, Warsage (BE)
Assigned to COCKERILL MAINTENANCE & INGENIERIE S.A., Seraing (BE)
Appl. No. 17/287,532
Filed by Cockerill Maintenance & Ingenierie S.A., Seraing (BE)
PCT Filed Oct. 14, 2019, PCT No. PCT/EP2019/077708
§ 371(c)(1), (2) Date Apr. 22, 2021,
PCT Pub. No. WO2020/083682, PCT Pub. Date Apr. 30, 2020.
Claims priority of application No. 18202302 (EP), filed on Oct. 24, 2018.
Prior Publication US 2021/0381092 A1, Dec. 9, 2021
Int. Cl. C23C 2/14 (2006.01); C23C 2/20 (2006.01); C23C 2/02 (2006.01); C23C 2/06 (2006.01); C23C 2/12 (2006.01)
CPC C23C 2/20 (2013.01) [C23C 2/02 (2013.01); C23C 2/06 (2013.01); C23C 2/12 (2013.01); C23C 2/14 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method for controlling and optimizing a transverse uniformity of a coating thickness on at least one side of a running metal strip in an industrial galvanization installation, the coating being deposited by hot dip coating in a pot containing a liquid metal bath, the method comprising at least the steps of:
heating the strip substrate to a temperature higher than a pot temperature;
passing the strip through the bath by wrapping the strip around at least a first deflector roll or sink roll followed by at least one second deflector roll, the second deflector roll being configured to improve a flatness of the strip;
wiping excess coating thickness carried away by the strip on one or both sides of the strip by wiping nozzles blowing a gas on the strip at an exit of the liquid metal bath;
measuring an actual distance profile between the nozzles and the strip along a direction transverse with respect to a running strip direction, and in a vicinity of the nozzles, so as to obtain an actual nozzle to strip distance profile curve;
using a computer, to calculate a first correction on the nozzle to strip distance profile curve based on a calculation of an average slope, comprising a 1st order linear regression straight line of the nozzle to strip distance profile curve, so as to apply the first correction based on a skewness of the nozzles and to set the nozzles parallel to the strip;
calculating a second correction on the first corrected nozzle to strip distance profile curve by subtracting from the curve a 2nd order linear regression quadratic line, a result thereof being a second corrected nozzle to strip distance profile curve, so as to apply the second correction to compensate for a crossbow by an adjustment of the deflector rolls in the pot; and
acting on the nozzles' position and transverse metal strip shape by physically transposing on the industrial galvanization installation the first and second calculated corrections, as a first corresponding physical correction and a second corresponding physical correction, by modifying firstly the position of the nozzles and secondly the shape of the strip respectively, so as to obtain a coated strip which is physically corrected in position and shape.