DE102006037728A1 - Mold for the continuous casting of liquid metal, in particular of steel materials - Google Patents

Abstract

A mold (1) for continuous casting of liquid metal, in particular of steel materials, has mold walls (1a, 1b,...) Of a substitution material (7) as copper replacement, wherein on the liquid metal side (5) a highly heat-conductive and high-temperature resistant protective layer (5). 8) is applied and on the rear cold side (6) coolant channels (4a) within the mold wall thickness (1b) are provided, which are spaced with coolant supply lines (9) and coolant discharge lines (10) are connected, wherein the mold walls in the thickness direction, a heat transfer Having coefficients (K) in the order of 2 to 20 W / m <SUP> 2 </ SUP> K.

Description

The The invention relates to a mold for the continuous casting of liquid metal, in particular of Steel materials whose mold walls are made of plates or plate-like Molded or manufactured as a tubular mold, wherein at least one mold wall made of steel material, and cooling media guides at the liquid metal facing away rear cold side are provided.

Such a mold is from the EP 1 286 795 B1 known, comprising at least one mold wall made of steel and a support grid for this Stahlkokillenwand. In addition, a magnetic field generator is present for generating a magnetic field, which acts on the support screen on the Stahlkokillenwand and thus pulls the Stahlkokillenwand on the support grid. In addition, the Kokillenkühleinrichtung is provided as a spray cooling, which leads from the outside via spray nozzles, the coolant against the support grid. The steel mold wall is formed of metal layers steel / copper or metal / steel / metal. The problem is the use of copper, which causes significant costs for manufacturing, maintenance and a limited life.

The Chill plate material is currently in practical use made of compact copper or copper alloys. These copper plates are screwed onto a steel water box. The copper plates are either uncoated, zoned or fully coated with Chrome, nickel or Cr / Ni alloys. The properties consist of a fast and quantitatively high heat loss due to the high thermal conductivity of Copper. The already indicated disadvantages are that copper through its softness has a high wear and a new leveling the entire mold after a reworking makes the worn copper plates necessary.

Of the Invention is based on the object by largely avoiding the use of the material copper or copper alloys more stable mold walls not or only to a limited extent reworked in the company Need to become and a repeated alignment of the entire mold is unnecessary.

The stated object is achieved in that the mold wall is coated on its side facing the liquid metal side with a highly thermally conductive and high temperature resistant protective layer; and the mold wall with the protective layer in the thickness direction from its hot side to its cold side, in particular in the region of the coolant channels, a heat transfer coefficient in the order of 2 to 20 W / m ² ρ K has.

The Advantages are the saving of expensive, relatively wear-prone Copper and a permanent permanent mold wall, which after a certain number of Abgießprozessen not must be reworked, but at most a new layer of protection receives and reinstalled in the rest of the mold assembly without reorienting can be. As a result, the downtime of a mold is shortened and it can less molds for a continuous casting plant be kept ready, which saves considerable operating costs. This means tet It is a considerable simplification that the Kokilienplattenmaße remain unchanged.

In Embodiment of the invention is provided that the substitution material made of steel material, aluminum alloys, ceramics or their layer combinations consists.

To Another embodiment of the invention is proposed that in the layer combinations a small proportion of copper particles containing 30% by volume does not exceed 50%.

Other Features are that the width and / or depth and / or Cross-sectional shape of incorporated in the substitution material Coolant channels for heat dissipation or the temperature control in the cast casting strands in dependence of their size or their cross section or depending casting parameters are suitably dimensioned.

Farther is provided that the heat-conducting and temperature-resistant protective layer on the liquid metal side of the carrier plate from metallic, non-metallic coatings or layer-by-layer combinations is formed.

there is a heat conduction properties of the Substitution material supporting Criterion given by the fact that the affinity or liability between the highly thermally conductive and high temperature resistant protective layer and the substitution material preferably high and between the protective layer and the respective casting material as low as possible is.

A Improvement consists in the fact that the mold wall immediately is placed tightly on a water tank and by means of a variety of tie rods against the base plate and the cover plate of the water box is clamped, wherein the width or depth of the cooling medium guide within the mold wall formed and by means of the continuous flat base plate of the water box is closed.

In the drawing are exemplary embodiments The invention is illustrated schematically and will be explained in more detail below.

It demonstrate:

1 a cross section through the mold with Kokillenwand and water tank and

2 a perspective view of the mold wall with protective layer on the liquid metal side and with the coolant channels on the cold side.

The mold 1 used for continuous casting of liquid metal, in particular steel materials, with cross sections of slab strands, thin strands, profile strands, Vorprofilsträngen, block strands, billet strands u. Like. The mold walls 1a . 1b They are made of plates or plate-like moldings or shaped as a tube mold. At the liquid metal side 5 facing away, rear cold side 6 are coolant channels 4 intended.

The mold walls 1a . 1b ... are inventively - unlike the known continuous casting molds - not made of copper or copper alloys, but of other materials, hereinafter as substitution materials 7 designated formed. The substitution materials serve as copper replacement and are preferably, similar to copper, highly thermally conductive and temperature resistant. The substitution material 7 consists for example of steel materials, aluminum alloys, ceramics or their layer combinations 7a , In some cases, it may be expedient that in a layer combination 7a a small proportion of copper particles is included which does not exceed 30% to 50%.

The mold walls are on the liquid metal side 5 with a high thermal conductivity and high temperature resistant protective layer 8th made of a protective material 3 overdrawn. This protective layer 8th With the simple mold of the mold wall, it can easily be applied in a sufficiently large vacuum space with corresponding substances by application via plasma jets of a plasma burner. For example, a metal carbide, a metal oxide, a cermet or an alloy of these materials is suitable as the surface-hardened material. The material for the protective layer can also consist of pulverized steel material particles. Other possible protective layer materials 8th are titanium nitride or titanium carbide. The protective layer or its protective material must - especially when cooling - be temperature resistant for temperatures of 1000 ° C-1700 ° C. The mold wall can be heated to an elevated uniform temperature before the coating process.

The thus coated mold wall is on its rear cold side 6 with coolant channels 4a within the mold wall thickness 1b Mistake. The coolant channels 4a are to a coolant supply line 9 and a coolant discharge 10 with flow directions from top to bottom ( 1 ) or from bottom to top. In this case, the mold wall in the thickness direction 1b especially in the field 4b the cooling channels ( 2 ) has a heat transfer coefficient K of the order of 2 to 20 W / m ² ρ K. The heat transfer coefficient K characterizes the heat conduction properties and thus the cooling behavior of the mold wall also in interaction with the cooling medium. With the definition of the heat transfer coefficient K in the said range 4b becomes the basis for the solidification of the cast strand in the area of the casting mirror 1c and in the casting direction 14 under the diving spout 1d or the slag layer 1e ( 1 ) placed.

worin bedeuten:

definiert als der Wärmedurchgangs-Koeffizient

Wärmeleitfähigkeiten der Materialien, aus denen sich die Kokillenwand zusammensetzen (Grundmaterial und Beschichtungen)
I[m] = Schichtdicken der Werkstoffe, aus denen sich die Kokillenwand zusammensetzen (Grundmaterial und Beschichtungen)

Wärmeübergangs-Koeffizient an der Kaltseite 6; seine Größe wird bestimmt durch die Strömungsgeschwindigkeit des Kühlmittels 11.The heat transfer coefficient K is defined as follows:

in which mean:

defined as the heat transfer coefficient

Thermal conductivities of the materials that make up the mold wall (base material and coatings)
I [m] = layer thickness of the materials that make up the mold wall (base material and coatings)

Heat transfer coefficient on the cold side 6 ; its size is determined by the flow rate of the coolant 11 ,

An adaptation of the heat conduction properties can also be done by the in the substitution material 7 incorporated coolant channels 4a with their width and or depth 12 and / or their cross-sectional shape as a regulator for the heat dissipation or the temperature control depending on the casting parameters (such as, casting speed, casting temperature, Gießstrangabmessungen and the like.) Serve.

An adaptability of the respective casting metal temperature to the mold wall properties results from the fact that the temperature-resistant protective layer 8th on the liquid metal side 5 the mold wall of metallic, non-metallic coatings 13 or from layered combinations 7a is formed.

The above values for heat transfer, thermal conductivity and temperature resistance are supported by placing the compact mold wall directly on a water box 15 is tight ( 1 ) and by means of a plurality of tie rods 16 against the base plate 15a and the cover plate 15b is braced, with the width or the depth 12 the coolant channels formed within the mold wall and by means of the flat base plate 15a is closed.

1

mold for continuous casting

1a

Molds (broadsides) wall

1b

Kokillenwanddicke

1c

meniscus

1d

A submerged nozzle

18

slag layer

3

Protective material

4a

Cooling media channel

4b

coolant leading section

5

Liquid metal (side)

6

cold side

7

Substitution material

7a

layer combination

8th

protective layer

9

Coolant supply

10

Coolant discharge

11

coolant

12

Width depth of the coolant channel

13

metallic / non-metallic coating

14

casting

15

cistern

15a

baseplate

15b

cover plate

16

tie rods

Claims (7)

Mold in the form of a plate mold or a tube mold for the continuous casting of liquid metal ( 5 ), in particular of steel materials, comprising at least one mold wall, which is formed from a substitute material as a copper substitute and which faces away from the liquid metal on the rear cold side ( 6 ) Coolant channels ( 4a ), wherein the coolant channels with coolant supply lines ( 9 ) and coolant discharges ( 10 ) are connected; characterized in that the mold wall is coated on its liquid metal facing side with a temperature-resistant protective layer; and the mold wall with the protective layer between its hot side and its cold side, in particular in the area ( 4b ) of the coolant channels, a heat transfer coefficient (K) in the order of 2 to 30 W / m ² ρ K has. Chill mold according to claim 1, characterized in that it is in the substitute material ( 7 ) to a steel material, aluminum alloys, ceramics or their layer combinations ( 7a ). Chill mold according to claim 2, characterized in that in the layer combinations ( 7a ) contains a proportion of copper particles which by volume does not exceed 50%. Mold according to one of the preceding claims, characterized in that the width and / or depth ( 12 ) and / or cross-sectional shape of the in the substitute material ( 7 ) incorporated coolant channels ( 4a ) are dimensioned suitable for the heat dissipation or the temperature control in the cast casting strands depending on Gießparametern. Chill mold according to one of the preceding claims, characterized in that the temperature-resistant protective layer ( 8th ) of metallic, non-metallic coatings ( 13 ) or layered combinations ( 7a ) is formed. Chill mold according to one of claims 1 or 4, characterized in that the affinity or adhesion between the material of the heat-resistant protective layer ( 8th ) and the substitution material as high as possible and between the material of the respective protective layer ( 8th ) and the respective casting material is as low as possible. Chill mold according to claims 1 and 4, characterized in that the mold wall directly on a water tank ( 15 ) is tightly fitted and by means of a plurality of tie rods ( 16 ) against the base plate ( 15a ) and the cover plate ( 15b ) of the water box is braced, wherein the coolant channels ( 4b ) extend in their width and depth direction within the mold wall and by means of continuous flat base plate ( 15a ) of the water box are closed.