Plating coating amount control mechanism and plating coating amount control method

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 through therebetween, the gas wiping nozzles being configured to blow gas onto the steel strip;
• a distance sensor disposed at an upstream side position preliminarily determined with respect to a transferring direction 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 of the steel strip;
• an upstream-side edge sensor disposed at the upstream side position with respect to the transferring direction of the steel strip and configured to detect an upstream-side edge position which is an 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 with respect to the transferring direction of the steel strip and configured to detect a downstream-side edge position which is an edge position of the steel strip;
• a plating adhesion amount meter disposed at the downstream side position with respect to the transferring direction 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 control part having a plating adhesion amount estimation expression for calculating a plating adhesion amount estimation value of a measurement surface portion which is a position on a surface of the steel strip being transferred at which the plating adhesion amount is to be measured, using following arithmetic elements at the time when the measurement surface portion passes the upstream side position:
• the nozzle-strip distance;
• a blowing pressure of the gas;
• a strip passing speed of the steel strip;
• and a specific strip width direction distance between the upstream-side edge position and the measurement surface portion which has an equal relationship with a distance in a strip width direction between the downstream-side edge position and the measurement surface portion,
• wherein the plating adhesion amount control part is configured to obtain a difference between the plating adhesion amount estimation value which is calculated when the measurement surface portion passes the upstream side position and the plating adhesion amount actual measurement value detected in a state where the plating adhesion amount meter faces the measurement surface portion when the measurement surface portion passes the downstream side position, and correct the plating adhesion amount estimation expression so as to reduce the difference to zero.