Method for dip-coating a metal strip

Patent metadata

Field	Value
Publication number	US-12435387-B2
Application number	US-202318196003-A
Country	US
Kind code	B2
Filing date	May 11, 2023
Priority date	Mar 12, 2018
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

Equipment for the continuous hot dip-coating of a metal strip 9 including an annealing furnace, a tank 2 containing a liquid metal bath 3 , a snout connecting the annealing furnace and tank 2 , through which the metal strip 9 runs in a protective atmosphere and the lower part of the snout, the sabot 5 , is at least partly immersed in the liquid metal bath 3 in order to define with the surface of the bath, and inside this snout, a liquid seal 6 , an overflow 7 not connected to the snout, the overflow 7 including at least one tray 8 , placed in the vicinity of the strip 9 when entering the liquid metal bath 3 and encompassed by liquid seal 6.

First claim

What is claimed is:

1. Equipment for continuous hot dip-coating of a metal strip, the equipment comprising:
an annealing furnace;
a tank containing a liquid metal bath;
a snout connecting the annealing furnace and the tank, the metal strip running through the snout in a protective atmosphere, a lower part of the snout being at least partly immersed in the liquid metal bath in order to define with a surface of the bath, and an inside of the snout, a liquid seal; and
an overflow independently movable with respect to the snout and including at least one tray placed in a vicinity of the strip when the strip enters the liquid metal bath and is located within the liquid seal, the at least one tray being formed by:
an internal wall facing one side of the strip, directed toward a surface of the liquid seal, an internal wall upper edge being positioned below the surface of the bath;
an external wall facing the snout, directed toward the surface of the liquid seal, an external wall upper edge being positioned above the surface of the bath;
a connector part between the external and internal wall lower edges and also
a side wall at each shared extremity of the internal and external walls connecting all edges;
the internal wall upper edge being lower than the external wall upper edge.

2. The equipment as recited in claim 1 wherein the snout is liftable and lowerable.

3. The equipment as recited in claim 1 wherein the overflow includes means for maintaining a level of liquid metal at a level below the surface of the liquid seal in order to set up a natural flow of the liquid metal in the at least one tray, the natural flow of the liquid metal being greater than 50 mm in order to prevent metal oxide particles and intermetallic compound particles from rising as a countercurrent to the flow of liquid metal.

4. The equipment as recited in claim 1 wherein the internal wall upper edge includes, in a longitudinal direction, a succession of hollows and projections.

5. The equipment as recited in claim 1 wherein the overflow is removable when the snout is lifted.

6. The equipment as recited in claim 3 wherein the at least one tray and the means for maintaining the level are fixed to the edges of the tank by supports.

7. The equipment as recited in claim 6 wherein the at least one tray is connected to the means for maintaining the level and support by connectors, the connectors of the overflow being curved towards a bottom of the coating bath so that a lowest part of the connectors is beneath the liquid seal allowing the lower part of the snout to be under the liquid seal and above a lowest part of the support.

8. The equipment as recited in claim 6 wherein the supports are movable along the edges of the bath allowing the overflow to shift along the edges of said bath.

9. The equipment as recited in claim 6 wherein the supports are shiftable along a perpendicular to the bath surface.

10. The equipment as recited in claim 1 wherein the overflow has two trays positioned symmetrically to an entry of the metal strip in the liquid metal bath.

11. The equipment as recited in claim 1 wherein the snout includes the lower part is removable.

12. The equipment as recited in claim 3 wherein the means for maintaining the level is a pump.

13. A method for depositing a metallic coating by hot-dip coating in the equipment as recited in claim 1 , the method comprising:
recrystallization annealing of the metal strip in an annealing furnace;
passing the metal strip from the annealing furnace to the liquid metal bath in the snout;
and hot dip-coating of the annealed metal strip in the liquid metal bath.

14. A method for replacing a worn lower part of a snout from a hot dip-coating process in the equipment as recited in claim 1 , the method comprising:
lifting the snout to set the lower part above the liquid bath, the lower part being revocable; and
lifting the overflow and removing the lower part of the snout and replacing the lower part by a new lower part.

15. Equipment for continuous hot dip-coating of a metal strip, the equipment comprising:
an annealing furnace;
a tank containing a liquid metal bath;
a snout connecting the annealing furnace and the tank, the metal strip running through the snout in a protective atmosphere, a lower part of the snout being at least partly immersed in the liquid metal bath in order to define with a surface of the bath, and an inside of the snout, a liquid seal; and
an overflow independently movable with respect to the snout and composed of one tray continuously surrounding the metal strip formed by an internal wall facing one side of the strip, directed toward the surface of the liquid seal, an internal wall upper edge being positioned below the surface of the bath, an external wall facing the snout directed toward the surface of the liquid seal, an external wall upper edge being positioned above the surface of the bath, a horizontal wall between the external and internal wall lower edges.

Assignees

• Arcelormittal

Inventors

• Garcia Martino Angel
• Garcia-Chapa Inocencio

Classifications

• C23C2/0224

  Two or more thermal pretreatments · CPC title

• C23C2/022

  by heating · CPC title

• C23C2/00344 Primary

  Means for moving substrates, e.g. immersed rollers or immersed bearings · CPC title

• C23C2/0222

  in a reactive atmosphere, e.g. oxidising or reducing atmosphere (C23C2/024 takes precedence) · CPC title

• C23C2/004

  Snouts · CPC title