Plating adhesion amount control mechanism and method for controlling an adhesion amount by comparing a plating adhesion amount estimation value at an upstream position and a plating adhesion actual amount at a downstream position

A plating adhesion amount control mechanism, comprising:

• a pair of gas wiping nozzles disposed such that a steel strip pulled up from a plating tank is transferred therebetween, the gas wiping nozzles being configured to blow a gas onto the steel strip;
• an upper setting position wherein a transferring direction of the steel strip is chanced to a horizontal direction;
• a distance sensor disposed at an upstream side position which is a position upstream to the upper setting position of the steel strip, the distance sensor being configured to detect a nozzle-strip distance which is a distance between the gas wiping nozzles and a strip surface;
• an upstream-side edge sensor disposed at the upstream side position the steel strip and configured to detect an upstream-side edge position which is a first edge position of the steel strip;
• a downstream-side edge sensor disposed at a downstream side position which is a position downstream of the upstream side position of the steel strip and configured to detect a downstream-side edge position which is a second edge position of the steel strip;
• a plating adhesion amount meter disposed at the downstream side position with respect to the upper setting position of the steel strip and configured to detect a plating adhesion amount of a metal plating layer formed on the steel strip and output a plating adhesion amount actual measurement value;
• and
• a plating adhesion amount controller having a plating adhesion amount estimation expression for calculating a plating adhesion amount estimation value of a first measurement surface portion which is a first position on the strip surface at which the plating adhesion amount is to be measured by the plating adhesion amount meter, when the first measurement surface portion passes the upstream side position using arithmetic elements including:
• the nozzle-strip distance;
• a blowing pressure of the gas;
• a steel strip passing speed;
• and a specific distance in a strip width direction between the upstream-side edge position and the first measurement surface portion, said specific distance is equal in distance in the strip width direction between the downstream-side edge position and the first measurement surface portion, wherein the plating adhesion amount controller is configured to obtain a difference between the plating adhesion amount estimation value which is calculated when the first measurement surface portion passes the upstream side position and the plating adhesion amount actual measurement value detected when the plating adhesion amount meter faces the first measurement surface portion and the first measurement surface portion passes the downstream side position, and correct the plating adhesion amount estimation expression so as to reduce the difference to zero.