A hot dip coating device to provide a metal coating on a moving metal sheet, containing a liquid bath of metal coating material in use. The metal coating material on the moving metal sheet in use, including a container for the liquid bath, a guide or sink roll in the container below liquid bath surface level in use to guide the moving metal sheet through the bath, and a gas knife, above the liquid bath in use, having an outlet to project wiping gas on the metal coating on the metal sheet. At least one supporting roll with the guide or sink roll in use influence metal sheet shape in its width direction at the gas knife location. The one supporting roll is above liquid bath surface level to operate on the metal sheet before the metal sheet enters the bath. A method for use of the device.

The present invention relates to an apparatus and a method of manufacturing a hot dipped galvanized steel sheet that is excellent in corrosion resistance and has no linear defects, thereby being available for automobile bodies, household appliances, construction materials, and the like which need aesthetic surfaces. The apparatus for manufacturing a hot dipped galvanized steel sheet includes: a plating pot filled with a galvanizing bath for coating of a steel sheet; a sink roll; a wiping device adjusting the thickness of the coating on the steel sheet; a top roll; an oxidation process chamber; and an air cooling device. According to the present invention, after an excess molten coating solution attached to the steel sheet is evenly removed, an oxide film is made to be 0.1 μm to 0.3 μm thick before a coating layer starts to solidify. Thus, linear defects can be prevented.

A method for monitoring a manufacturing of a metal product, the metal product being manufactured according to a manufacturing process, is implemented by an electronic monitoring device. This method includes acquiring (100) a measured value of at least one representative parameter, each representative parameter being a parameter relating to the metal product or a parameter relating to the manufacturing process, determining (130) a status of the metal product among a compliant status and an analysis status, depending on the at least one acquired value and on at least one target, and when the determined status is the analysis status, computing (150) a corrective action to be applied to the product, among a set of corrective actions and depending on the at least one acquired value, the set of corrective actions including a product repair, a product downgrading, a product expertise and a product acceptance.

An apparatus for cooling a steel sheet includes: an apparatus body provided spaced apart from a steel sheet in the conveying path of the steel sheet; and a cooling unit provided in the apparatus body to supply a cooling fluid. The apparatus body includes: a first edge body that faces a first edge portion extending a certain distance from one side end of the steel sheet toward the center of the steel sheet; and a second edge body that faces a second edge portion extending a certain distance from the other side end of the steel sheet toward the center of the steel sheet. The first and second edge bodies may have stepped cross-sections in a direction perpendicular to the conveying direction of the steel sheet.

Provided is a plated steel sheet having an excellent quality with fine and even plating texture, the plated steel sheet including a base steel sheet and a Zn plating layer formed on the base steel sheet, wherein a Zn crystal in the plating layer has a size of 5 μm or less.

Provided is a continuous hot-dip galvanizing apparatus comprising: a vertical annealing furnace having heating, soaking zone, and cooling zones therein; and a hot-dip galvanizing line downstream of the cooling zone. The heating, soaking, and cooling zones each have, in its upper portion, at least one upper hearth roll and, in its lower portion, at least one lower hearth roll. The soaking zone has a first and second humidified gas supply ports to supply a humidified gas having a dew point of 10° C. to 30° C. to the soaking zone. The first and second humidified gas supply ports are 1.0 m to 5.0 m lower than the center of the lower and upper hearth rolls, respectively, and overlap the steel sheet. The first humidified gas supply port is provided only for an ascending pass and the second humidified gas supply port is provided only for a descending pass.

A method manufacturing a steel strip, including the subsequent steps of hot rolling the strip into a hot rolled strip, cold rolling the hot rolled strip and hot dip coating the cold rolled strip with a Zn based coating by leading the strip through a bath including molten zinc and wiping the strip after the coating using a gas knife having a knife slot from which a wiping gas is projected and the steel strip is cold rolled to a final cold rolled thickness of between 0.40 mm and 1.00 mm in a multi-stand cold rolling mill, and the coated steel sheet includes a steel substrate provided with a hot dip metal coating.

A wiping device 14 includes a pair of wiping nozzles 141, a nozzle mask 142, a rotating pin 1431a, a holding portion 1431b, and an arm portion 1432. The pair of wiping nozzles 141 is disposed such that nozzle ports 141a face each other, the nozzle mask 142 is disposed at both ends of the nozzle ports 141a of the wiping nozzles 141, the rotating pin 1431a is connected to an upper portion of the nozzle mask 142, the holding portion 1431b holds the rotating pin 1431a, the arm portion 1432 fixes the holding portion 1431b from above, and the rotating pin 1431a is rotatable around an axis and adjusts the position of the nozzle mask 142.

Disclosed is a treatment line for the continuous treatment of metal strips having a dual purpose, i.e. for producing strips that are annealed and dip-coated with a metal alloy and for producing strips that are annealed and not coated, comprising a dual-purpose cooling tower, i.e. for cooling strips that are annealed and not coated in a non-oxidizing atmosphere and for air-cooling strips that are annealed and coated.

A device for removing foreign material from a molten metal surface in a steel sheet hot-dip galvanizing process, of the present invention, comprises: a snorkel part of which the end portion is submerged under the molten metal surface of a hot-dip galvanizing bath so as to encompass a steel sheet inserted into the hot-dip galvanizing bath, in order to prevent the oxidization thereof; a snout including a dam unit having a dam forming part which encompasses the steel sheet from the end portion of the snorkel part so as to be spaced a predetermined gap from same, and which allows a molten galvanizing solution inside the hot-dip galvanizing bath to flow over toward the inner peripheral surface of the snorkel part so as to prevent the foreign material that falls onto the molten metal surface inside the snorkel part from attaching to the steel sheet; and a molten zinc discharge unit which is provided inside the snorkel part so as to pump, toward the molten metal surface inside the hot-dip galvanizing bath, the molten galvanizing solution having flowed over the dam forming part of the damp unit, thereby preventing the foreign material included in the molten galvanizing solution, having flowed over the dam forming part, from mixing into the molten galvanizing solution inside the hot-dip galvanizing bath and re-polluting the molten galvanizing solution or flowing into the snorkel part again.