JP2828401B2 - Metal sheet casting drum and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct production of a thin metal sheet, and more particularly to a casting drum having a casting surface having a multi-layered structure, an inner boundary surface having irregularities, and a plating surface.

[0002]

2. Description of the Related Art In recent years, a twin-drum continuous casting method has been proposed as one of the methods for directly manufacturing a thin plate from a molten metal. In this twin-drum continuous casting method, since the cooling rate is higher than in the case of conventional continuous casting using a fixed mold, crack defects are easily generated on the slab surface. Therefore, the inside of the casting drum is made of a copper alloy, the surface of the casting surface is plated with Ni or the like to achieve slow cooling, and furthermore, the application of heat insulating material as proposed in Japanese Utility Model Publication No. 63-133863 or JP-A-1-83
As proposed in Japanese Patent Publication No. 340, it has been practiced to provide a more moderate cooling effect by adding irregularities to the casting surface.

[0003]

In the conventional heat insulating material application, the main purpose is to apply the heat uniformly to the surface of the casting surface of the mold. It depends on the material selection or the adjustment of the coating thickness. Therefore, it has been difficult to prevent the occurrence of minute crack defects in the cast slab due to the solidification characteristics of the metal.
On the other hand, applying unevenness to the surface of the casting surface of the mold is effective in preventing the occurrence of minute crack defects in the slab due to the solidification characteristics of the metal, but excessive unevenness is transferred to the slab. In addition, the life of the irregularities formed on the casting surface of the mold is relatively short, which has been a problem. The present invention provides a casting drum free from the occurrence of such slab cracks and having improved durability, and a method for producing the same.

[0004]

According to the present invention, in order to solve the drawbacks of adjusting the cooling rate by the conventional method, the inner layer of the casting surface is made of a copper alloy which is a material having high thermal conductivity, and the surface of the inner layer is formed of a low heat conductive material such as nickel. In a casting drum in which a multi-layer structure is formed by plating a conductive material, irregularities are provided on the surface of a high heat conductive material, and a low heat conductive material is plated thereon.

That is, the metal sheet casting drum of the twin-drum continuous casting machine of the present invention has the following features. (1) A casting drum having a multilayer structure in which a surface layer of a casting surface is formed of a low thermal conductive material and an inner layer is formed of a high thermal conductive material, wherein irregularities are formed at an interface between the low thermal conductive material and the high thermal conductive material. At the same time, the surface of the casting surface is made smooth.

(2) In the above (1), the high thermal conductive material forming the inner layer is silver copper or chromium-zircon copper, and the equivalent diameter of the concave and convex concave portions provided on the inner layer surface is 0.1.
~ 2mm, depth 0.1 ~ 2mm, the area ratio of which is 3
0 to 50%. (3) In the above (1) or (2), the low thermal conductive material layer forming the surface layer is a pure nickel plating layer or
It is a nickel-dissimilar material plating layer containing iron, tungsten, or a non-metal, or a cobalt-nickel plating layer, and the average thickness of the plating layer is 0.3 to 2 mm.

(4) In the above (1) to (3), unevenness processing is performed on the outermost surface of the casting surface so as to have an equivalent diameter of not more than half of the unevenness provided on the boundary surface between the inner layer and the surface layer. It is. Further, a method for manufacturing a metal sheet casting drum of a twin-drum continuous casting machine according to the present invention has the following features. (A) The casting drum according to any one of the above (1) to (4)
A manufacturing method, wherein a sleeve surface of a high heat conductive material is
Glass processing, shot processing, electric discharge processing, laser processing,
Alternatively, unevenness processing is performed by etching.

(B) Any one of the above (1) to (4)
A method for manufacturing a casting drum, wherein a low thermal conductive material is plated on the outside of a sleeve made of a high thermal conductive material having an uneven surface. In particular, the present method is applied to a sleeve that has been subjected to the unevenness processing of (a).

[0009]

In recent years, there has been proposed a method of directly manufacturing a thin plate from a molten metal by using a continuous casting apparatus. For example, for a thin plate having a thickness of several millimeters, a twin-drum continuous casting apparatus has been proposed as one of so-called synchronous mold continuous casting apparatuses in which a slab and a mold move synchronously. In this twin-drum continuous casting apparatus, the cooling rate is higher than in a conventional fixed mold continuous casting apparatus, and crack defects are likely to occur on the slab surface. This is because in a conventional fixed mold continuous casting apparatus, powder or repseed oil is used for lubricating the mold, and as a result, a heat resistance layer is formed between the molten metal and the mold, thereby forming a twin drum continuous casting machine. This is due to slow cooling compared to In the twin-drum type continuous casting machine, in order to suppress the cooling rate and eliminate cracking defects on the surface of the slab, it has been proposed to apply a heat insulating material as disclosed in Japanese Utility Model Application Laid-Open No. 1333863/1988 or disclosed in As disclosed in Japanese Unexamined Patent Publication No. 83340/1989, slow cooling is performed by performing unevenness processing on a casting surface. 63-133
When applying a heat insulating material as proposed in Japanese Patent No. 863, the main focus is on applying the heat insulating material uniformly to the surface of the casting surface of the drum. The selection of the material of the coating material or the adjustment of the coating thickness is performed. Therefore, it has been difficult to prevent minute crack defects in the cast slab due to the solidification characteristics of the metal.
On the other hand, when the casting surface of the drum is roughened as proposed in JP-A-1-83340, excessive unevenness is transferred to the slab and the life of the drum is reduced due to the wear of the casting surface. Had the disadvantage of being short.

The present invention solves such a drawback in the conventional cooling rate adjustment by locally changing the thickness of the low thermal conductive material on the drum surface. The surface of the provided copper alloy sleeve of a high thermal conductivity material is plated with a low thermal conductivity material such as nickel to form a multilayer structure. According to the structure of the present invention, the thickness of the low thermal conductive material layer on the surface layer becomes uneven, and heat is locally unevenly removed from the slab surface during casting, so that the thermal stress acting on the solidified shell of the slab is reduced. It can be finely dispersed, and the surface crack defect of the slab can be prevented.

[0011]

1 is a sectional view of a drum according to the present invention, and FIG.
FIG. In the figure, reference numeral 1 denotes a low thermal conductive material layer (plating layer mainly composed of nickel), 2 denotes a sleeve made of a high thermal conductive material (copper alloy), and 3 denotes a surface of the high thermal conductive material between the sleeve and the low thermal conductive material. 4 is a cooling water hole, 5 is an arbor. In the present invention, in the casting drum having such a structure, irregularities are formed on the boundary surface between the sleeve 2 made of the high thermal conductive material and the low thermal conductive material layer 1, and the surface of the casting drum is made smooth. By doing so, the thickness of the low thermal conductive material layer 1 outside the sleeve 2 becomes non-uniform, so that at the time of casting, local non-uniform heat removal occurs from the slab surface. As a result, it is possible to finely disperse the thermal stress acting on the solidified shell of the slab, and it is possible to obtain a slab having no surface crack defects and a smooth surface. Further, the wear of the casting drum surface is extremely small, and the life of the casting drum can be extended. The size of the irregularities on the surface of the sleeve made of the high thermal conductive material (copper alloy) varies depending on the metal to be cast. However, in the case of continuous casting of steel, the equivalent diameter of the recess is 0.1 to 2 mm and the depth is The area ratio of the concave portion is preferably 0.1 to 2 mm and 30 to 50%. In addition, as a method of processing the concavities and convexities, cone processing, chisel processing, shot processing, electric discharge processing, laser processing, etching processing, and the like are appropriate. do not have to. In the case of casting steel, the thickness of the plating layer containing nickel as a main component is appropriately in the range of 0.3 mm to 2 mm, preferably 0.5 to 1 mm. If the thickness is less than 0.3 mm, the thickness of the nickel layer at the portion corresponding to the convex portion of the copper alloy sleeve becomes extremely small, and the copper alloy sleeve is deformed by the pressing force of the twin drum. If the thickness is more than 2 mm, the temperature of the surface of the cast surface of the nickel plating layer becomes excessively high, and the nickel plating layer is likely to be deformed. The surface of the casting surface is desirably smooth. However, when the metal to be cast is not limited to one type, it is necessary to select a nickel plating thickness that can support all of the metal to be cast, and when it is not possible to specify the uneven shape of the internal boundary surface to one type, In some cases, a heat insulating material may be applied to the surface of the casting surface or irregularities may be formed on the surface layer of the casting surface. However, these surface treatments may be minor compared to the conventional case in which the inner boundary surface is not provided with irregularities. Is small, and the effect of the present invention is not lost.

The low thermal conductive material used for the casting surface may be a pure nickel plating layer, a nickel-dissimilar material dispersed plating layer containing a few percent of a nonmetal such as iron, tungsten or phosphorus or sulfur, or cobalt. -A material having a higher strength than nickel, such as a nickel plating layer, is suitable. As a material for the copper sleeve, copper alloys such as silver copper and chromium-zircon copper, which are higher in strength than pure copper, are suitable because of the thermal conductivity, the cooling method of the copper sleeve, the thickness of the sleeve, the amount of heat removal, and the temperature of each part of the drum. .

[0013]

By applying the present invention to twin-drum continuous casting, it is possible to produce a thin plate slab having no crack defect on the slab surface and a smooth surface, and to prolong the service life of the drum surface. Was.

[Brief description of the drawings]

FIG. 1 is a sectional view of a drum according to the present invention.

FIG. 2 is an enlarged view of a drum section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Nickel plating layer 2 ... Copper alloy sleeve 3 ... Internal boundary surface 4 ... Cooling water hole 5 ... Arbor

Continuation of the front page (56) References JP-A-5-318151 (JP, A) JP-A-5-212505 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 11 / 06 330

Claims (6)

(57) [Claims] 1. A casting drum of a twin-drum type continuous casting machine, wherein a casting layer having a multilayer structure in which a surface layer of a casting surface is formed of a low thermal conductivity material and an inner layer is formed of a high thermal conductivity material. A metal sheet casting drum characterized in that unevenness is provided at a boundary surface between a low thermal conductivity material and a high thermal conductivity material, and the surface of a casting surface is smooth. 2. The high thermal conductive material forming the inner layer is silver copper or chromium-zircon copper, and the equivalent diameter of the concaves and convexes provided on the surface of the inner layer is 0.1 to 2 mm, and the depth is 0.1 to 2 mm. 2mm
2. The metal sheet casting drum according to claim 1, wherein the area ratio is 30 to 50% of the whole. 3. The low thermal conductive material layer forming the surface layer is a pure nickel plating layer, a nickel-dissimilar material dispersed plating layer containing iron, tungsten, or nonmetal, or a cobalt-nickel plating layer, and the plating is performed. 3. The method according to claim 1, wherein the layer has an average thickness of 0.3 to 2 mm.
A sheet metal casting drum as described. 4. An outermost surface of a casting surface is subjected to an unevenness processing having an equivalent diameter of a concave portion which is equal to or less than half of an unevenness provided at a boundary surface between an inner layer and a surface layer. A metal sheet casting drum according to any one of the above. 5. A method for producing a casting drum of a twin-drum continuous casting machine according to claim 1.
A method for manufacturing a metal sheet casting drum, wherein a surface of a sleeve made of a high thermal conductive material is subjected to projections and depressions, shots, electric discharges, lasers, or etchings. 6. A method for producing a casting drum of a twin-drum continuous casting machine according to claim 1.
A method of manufacturing a thin metal sheet casting drum, wherein a low thermal conductivity material is plated outside a sleeve made of a high thermal conductivity material having a textured surface.