LU87990A1 - INTERNALLY COOLED ROLE OF A CONTINUOUS CASTING PLANT AND METHOD FOR THEIR PRODUCTION - Google Patents

Description

REVENDICATION DE LA PRIORITE de la demande de brevet

En Allemagne

You 24 août 1990

No P 40 27 225.7-24 Mémoire Descriptif déposé à l'appui d'une demande de

BREVET D'INVENTION au

Luxembourg au nom de: mannesmann corporation

Manne smannufer, 2 D-4000 Düsseldorf 1 pour: "Internally cooled roll of a continuous caster and

Process for their preparation "

Internally cooled roile of a continuous caster and process for its manufacture

The invention relates to an internally cooled roller of a continuous casting installation, in particular a support and guide roller, with a jacket of copper or a copper alloy surrounding a core made of iron material and connected to the core, and with a jacket! surrounding wear protection and a process for their manufacture.

In continuous casting plants, the rollers, in particular the driven rollers and the rollers directly adjoining the mold, are subject to high wear from the hot strand. Therefore, many attempts have been made over the years to optimize the wear resistance of the rollers.

From Japanese publication Sho-52-40608, an internally cooled continuous cast roll with a core, a jacket surrounding the core and a further wear protection jacket surrounding the jacket is known. The jacket around the core is made of copper, a copper-nickel alloy, a copper-aluminum alloy or aluminum.

The wear protection jacket is made of steel or cast iron and is especially connected to the inner jacket via a shrink fit.

From this document the basic structure is known to surround a core of a continuous casting roll with a jacket made of copper and to slit this over another jacket before wear, but the heat conduction is reduced by the steel or cast jacket with a lower thermal conductivity than copper. In addition, the wall thickness required for strength reasons to shrink on the steel or cast iron jacket has a negative effect on the heat conduction.

The German published patent application DE 26 36 199 A1 describes a method for producing tempered rolls of continuous casting plants with a protective layer. The protective layer made of a Cr-Ni alloy is applied by spraying and then sintered. The protective layer is then mechanically finished to a final dimension of at least 1 mm.

The disadvantage of sprayed-on protective layers is their low adhesion, since these are only mechanically clamped to the roughened surface of the base material. In addition, these layers cannot be applied with the same wall thickness, so that post-processing is required.

An internally cooled roll with a wear layer applied by cladding is known from a more recent patent specification DE 37 35 884 Cl. The wear layer is arranged on a jacket made of round bars and welding material fillings in between, the round bars covering open cooling channels integrated into a core. If necessary, the wear layer is applied in several layers and then finished.

Experience has shown that two layers with a total thickness of approximately 5-8 mm are applied in order to avoid mixing of the welding material with the jacket on the one hand and to obtain a required finishing allowance of 2 mm on the other.

All of the above proposals have the common disadvantage that the heat conduction from the strand towards the coolant is reduced by the thickness and poor thermal conductivity of the wear protection layer.

The object of the invention is to provide an internally cooled, dimensionally stable roll of a continuous casting plant with high wear resistance and at the same time high thermal conductivity and to specify a process for its production.

The object is achieved with an internally cooled roll according to the preamble of claim 1 with the features of the characterizing part of claim 1. Advantageous further developments of the invention are specified in the subclaims.

The invention likewise specifies a method for producing an internally cooled roll according to claims 1-7. The method is distinguished by the fact that an intermediate layer is applied galvanically to the copper or copper alloy sheath and at least one cover layer is welded onto the intermediate layer by means of a resistance roller seam cladding.

According to the invention, the intermediate layer, in particular made of a galvanically applied nickel layer, enables the copper jacket to be provided with an overlay welded covering layer. The nickel layer has dimensions of 0.3 - 1 mm, and a lower thermal conductivity than the copper jacket. During welding, this layer reduces the dissipation of heat through the copper jacket and thus enables the welding material to be completely melted and welded to the intermediate layer. The use of a resistance roller seam build-up welding process · provides cover layers, in particular made of Ni-Cr-B alloys, as wear protection with a high adhesion to the base material and thicknesses of less than 1 mm. With this method it is also possible to incorporate hard materials, in particular tungsten carbide, into the welding material to increase the wear resistance of the layer.

The roll produced by the process according to the invention is characterized overall by a high thermal conductivity and insensitivity to thermal shocks by the small layer thicknesses of the nickel and wear protection layer, excellent wear resistance by the welded layer and a large dimensional stability by the core made of iron material.

From the patent specification DD 225 334 A1, a method and a device for resistance roller seam cladding with filler metals, in particular metal powders (e.g. nickel-chromium-boron <silicon alloys), for armoring or reinforcing components (e.g. steel cylinders) is known. However, direct coating of non-ferrous metals, in particular copper or copper alloys, is neither described nor possible. In addition, the document contains no information on the achievable layer thicknesses of less than 1 mm.

The invention is explained below with reference to the drawing.

FIG. 1 shows a longitudinal section of a roll with a spiral-shaped coolant channel. The roller essentially consists of a core 1 made of iron material, a jacket 2 of copper or a copper alloy surrounding the core 1 and a wear protection surrounding the jacket 2. The wear protection is made up of an intermediate layer 3 made of nickel, which is applied, in particular, galvanically to the jacket 2, and an overlay layer 4 which is welded on. The jacket 2 is connected to the core 1 via a snug fit, in particular via a shrink connection. In addition, the jacket 2 is fastened to the core 1 at least at an edge 5 via a welded connection 6. In the . A coolant channel 7 in the form of a helical groove which is single or multiple to the longitudinal direction L of the core 1 is incorporated into the surface of the core 1. The Klihlmittelkanal 7 is covered by the tubular jacket 2. In the area of the edges 5 of the jacket 2, the coolant channel 5 is connected to coolant connections 9 via radially extending bores 8. The Klihlmittelanschliisse 9 are arranged concentrically on the core 1 and adjoining bearing pins.

Although the invention is described on the basis of a roll with a single-layer cover layer 4, the cover layer applied by the resistance roller seam cladding can also be implemented in multiple layers with a small overall thickness. Since the teaching according to the invention relates to the coating of the copper cladding, it can also be implemented in the case of full rolls of copper without a core.

Position list 1 core 2 jacket 3 intermediate layer 4 cover layer 5 edge of the jacket 6 welded joint 7 coolant channel 8 bore 9 coolant connection 10 bearing pin L longitudinal direction of the core 1

Claims (8)

Internally cooled roll of a continuous caster and process for its manufacture! 1. Internally cooled roll of a continuous caster, in particular a supporting and guiding roll, with a jacket made of iron material and connected to the core made of copper or alloys and with a wear protection surrounding the jacket, characterized in that the wear protection is applied to the jacket from the jacket There is an intermediate layer with a low thermal conductivity than copper and at least one cover layer welded onto the intermediate layer. 2. Internally cooled roll according to claim 1, characterized in that the intermediate layer made of nickel and is applied galvanically. 3. Internally cooled roll according to claim 1 or 2, characterized in that the thickness of the intermediate layer is 0.3 - 1 mm. 4. Internally cooled roll according to one of claims 1 to 3, characterized in that the covering layer applied by resistance roll seam build-up welding has a thickness of at most 1 mm, in particular 0.2-0.5 mm. 5. Internally cooled roll according to one of claims 1 to 4, characterized in that the cover layer consists of a Ni-Cr-B alloy. 6. Internally cooled roll according to one of claims 1 to 5, characterized in that hard materials are embedded in the cover layer. 7. Internally cooled roll according to one of claims 1 to 6, characterized in that the cover layer is designed in multiple layers. 8. A method for producing an internally cooled roll according to claims 1 to 7, characterized in that an intermediate layer is applied galvanically to the jacket made of copper or a copper alloy and at least one cover layer is welded onto the intermediate layer via a resistance roll seam weld.