Patent ID: 11866829
Assignee: JOHN COCKERILL S.A.
Field: Surface technology, coating (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A gas wiping device for controlling a thickness of a coating layer deposited on a running strip, comprising a metal strip plated with molten metal in an industrial hot-dip installation, the device comprising:
a main nozzle unit and a secondary nozzle unit, configured to blow a wiping jet on a surface of the running strip, the main nozzle unit and secondary nozzle unit respectively comprising a main and secondary chamber fed by pressurized non-oxidizing gas and at least a main elongated nozzle slot formed in a tip of the main nozzle unit and a secondary elongated nozzle slot formed in a tip of the secondary nozzle unit, each tip having an external top side facing a downstream side of the running strip and making an angle with the surface of the running strip,
wherein the secondary nozzle unit is adjacent the main nozzle unit over the external top side of the main nozzle unit tip such that an upper external surface of the secondary nozzle unit forms an angle of between 5° and 45° with the surface of the running strip surface,
wherein a thickness of an opening of the secondary elongated nozzle slot is between 1.5 and 3 times a thickness of an opening of the main elongated nozzle slot,
wherein the external top side of the secondary nozzle unit tip is extended downstream by a first baffle plate making a first angle with respect to the running strip so as to form a gas confinement region, and
wherein the gas wiping device further comprises:
an actuator configured to adjust a distance between a tip of the first baffle plate and the running strip, the first baffle plate being mounted pivotably with respect to the upper external surface of the secondary nozzle unit using a hinge, such that the actuator is configured to modify an angle between the first baffle plate and the upper external surface of the secondary nozzle unit; and
an oxygen sensor in the gas confinement region, close to an opening of the secondary elongated nozzle slot of the secondary nozzle unit, the oxygen sensor being configured to measure an amount of oxygen close to the running strip, downstream of a nozzle location of the main nozzle unit, so as to provide a measurement for activating the actuator, wherein the actuator is configured to modify a geometry of the gas confinement region based on the measurement of the oxygen sensor by varying a distance in order to reduce an oxygen content in the gas confinement region or to keep the oxygen content in the gas confinement region below a predetermined threshold.