METHOD AND DEVICE FOR IN-LINE SURFACE TREATMENT OF SLABS

• US 20130014362A1
• Filed: 01/10/2011
• Published: 01/17/2013
• Est. Priority Date: 01/14/2010
• Status: Active Grant

• Current Assignee: SMS Siemag AG (Bernhard-Weiss-Stiftung)
• Original Assignee: SMS Siemag AG (Bernhard-Weiss-Stiftung)
• Inventors: Bilgen, Christian, Neumann, Luc, Klinkenberg, Christian, Bcher, Tilmann, Gathmann, Marcel
• Granted Patent: US 8,572,826 B2
• Time in Patent Office: Days
• US Class Current: 29/81.06
• CPC Class Codes: B21B 45/004 Heating the product
• CPC Class Codes: B23K 7/06 Machines, apparatus, or equipment specially designed for scarfing or desurfacing
• CPC Class Codes: Y10T 29/45 Scale remover or preventor
• CPC Class Codes: Y10T 29/4517 Rolling deformation or deflection
• CPC Class Codes: Y10T 29/4533 Fluid impingement
• CPC Class Codes: Y10T 29/4539 with heater
• CPC Class Codes: Y10T 29/4544 Liquid jet

Abstract

The aim of the invention is to improve the surface quality of slabs (5) having a thickness of up to 400 mm, that are produced in a continuous process from continuous casting to hot-rolling, for example according to the CSP method, by means of an in-line surface treatment. To this end, a defined surface layer of the slab (5) with a layer thickness per slab side of up to 4 mm is oxidised in a targeted manner by an oxidising flame or an oxidising gas mixture applied to the upper and lower sides of the slab (5) by means of an oxidation device containing nozzles or a similar device, said layer being removed later on during the process. The oxidation product on the slab surface can be solid or liquid.

Claims

1. Method for improving the outer surface quality by an in-line outer surface treatment of slabs (5), which are produced in a continuous process from strand casting to hot rolling, for example pursuant to the CSP-process with a heating furnace (3) arranged between the CSP-casting machine (2) and the hot rolling train (4), wherein a defined surface of the slab (5) with a layer thickness per slab side of up to 4 mm is oxidized in a targeted manner by an oxidizing flame or an oxidizing gas mixture applied to the upper and lower sides of the slab (5) by means of an oxidation device (21) containing nozzles or nozzle-like devices;

the oxidation product on the slab surface can be solid or liquid, wherein the oxidation treatment of the slab surface with an oxidizing flame or with an oxidizing gas mixture is combined with the following processing in-line method steps;

prior to the oxidation treatment the outer surface of the slab is freed of naturally occurring scale by a low pressure or high pressure scale washer (22),

after the oxidation treatment the created oxidation layer as well as the newly formed scale is cooled by water cooling nozzles (23) or other appropriate media or tasks, mechanically broken up in a roll pair (8) and removed from the surface of the slab by a low pressure scale washer (9) or a conventional high pressure scale washer (10).

2. Method according to claim 1, wherein for the targeted creation of oxidized layer thicknesses the following settings of the oxidation device (21) are carried out, either alone or in combination:

variation of the oxidation potential of the flame or the gas mixture applied to the slab outer surface for oxidation,

variation of the volume stream of the gas used for oxidation,

variation of the oxidation potential and/or the volume stream of the gas used for oxidation in dependence on the process parameter such as for example slab transport speed and steel quality,

variation of the spacing and the angle of the nozzles or the nozzle-like devices of the oxidation device (21) to the slab surface,

construction and number of the nozzles or the nozzle-like devices (21).

3. Method according to claim 1, wherein the outer surface treatment is carried out over the entire slab width.

4. Method according to claim 1, wherein the outer surface treatment is carried out variably limited by being targeted to local or isolated sections of the slab width or length.

5. Method according to claim 3, wherein dependent on the process parameters such as for example steel type, casting speed, no-steady-state process conditions, the outer surface processing is limited to production subsets.

6. Method according to claim 3, wherein in dependence on the prevailing location conditions, the outer surface treatment of the slab (5) is carried out in-line after exit from the casting machine (2) and before entry in the heating furnace (3) or alternatively after exit from the heating furnace (3) and before entry into the hot rolling train (4).

7. Apparatus for improving the outer surface quality by an in-line outer surface treatment of slabs which are produced in a continuous process from strand casting to hot rolling, for example according to the CSP-process with a heating furnace (3) arranged between the CSP-casting machine (2) and the hot rolling train (4), in particular for carrying out the method according to claim 1, comprising an outer surface treating device (20), including:

a scale washer (22) operated in low or high pressure ranges,

an oxidation device (21) containing a nozzle or nozzle-like device for applying an oxidizing flame or an oxidizing gas mixture on the slab surface,

wetting nozzles (23) for cooling and for embrittling the layers produced by the nozzles or nozzle-like devices of the oxidation device (20) on the outer surface of the slab by oxidation,

as well as a roll pair (8) following this outer surface treatment device (20) for mechanically breaking up the embrittled layers as well as a scale washer (9, 10) that operates in low or high pressure range for removing the broken up layers from the slab surface.

8. Apparatus according to claim 7, wherein all apparatuses and devices (21, 22, 23) of the outer surface treatment device (20) as well as all subsequently arranged devices (8, 9) are constructed so as to be drivable individually or in combination into and out of the production line.

9. Apparatus according to claim 7, wherein the apparatuses and devices (21, 22, 23, 8, 9) required for outer surface treatments, in addition to their drivability, are constructed and arranged in the production line so that the outer surface treatments can be carried out over the entire slab width or selectively targeted to local or isolated sections of the slab width or length.