EP2665842B1 - Exterior wall metal sheet made of aluminium having a high surface roughness - Google Patents

Description

The invention relates to a facade sheet or strip of aluminum or an aluminum alloy of the type AA 5005 with a thickness of more than 2 mm to 4 mm and a method for its production.

Exterior facades of buildings are often clad with brushed steel sheets, which have a special look due to their rough surface. The problem with the use of steel sheets, however, is that they have a high weight and therefore an increased effort in terms of mounting structure and overall higher strength requirements for the facade to which they are attached, provide. Furthermore, steel sheets corrode, so expensive stainless steels must be used. In the field of furniture production, for interior ceiling panels or in the kitchen area, the use of anodized and anodized aluminum sheets is known, which have a so-called "butler-finish" structure due to the grinding structure of the rolls. The sheets used for furniture, ceiling panels, in the kitchen area, for stand and fair construction as well as for doors and window accessories usually have a thickness of up to 1.5 mm or significantly less and are with a maximum of 10 microns thick anodization on the visible side delivered. A use of these aluminum alloy sheets for facades was previously not possible due to the small thicknesses. In addition, the use was of aluminum or aluminum alloys in the field of external facades problematic, since in particular problems were observed with a constant surface appearance under the influence of the weather.

From the US 4,715,901 For example, architectural sheeting for cladding buildings made of 5XXX type aluminum or aluminum alloy, in particular 5005 type, and having a thickness of 0.02 to 0.25 inches on (0.5 to 6 mm) are known.

Finally, from the JP 4-041003 Aluminum sheets for covering buildings are known, which are processed at the end of their production with rollers such that a surface roughness of 0.3 to 1.6 microns is formed.

The object of the present invention is to propose an alternative to the previously used steel sheets in the area of the outer facades of buildings.

The object shown is achieved according to the teachings of the present invention by a cladding sheet or strip of aluminum or aluminum alloy of type AA 5005, characterized in that the cladding sheet has an average roughness R _a of 1.2 microns to 1.7 microns, wherein the mean roughness R _z of 7 microns to 12 microns measured according to DIN EN ISO 4287.

The mentioned Rautiefewerte ensure an attractive appearance, which is similar to that of steel sheets. In addition, ensure sheet metal or strip thicknesses of more than 2 mm and a maximum of 4 mm sufficient strength of the cladding sheet or strip, for example, against wind, preferably sheet metal or strip thickness of 2.5 mm to 4 mm can be used. On the other hand, even a cladding sheet or strip with the maximum thickness of 4 mm ensures a significant weight advantage over steel sheets with similar strength, so that can be dispensed with elaborate mounting structures on the facade.

According to a first embodiment of the facade sheet or bands, the stroke length, ie the length of the roll structures pressed in on the sheet or strip, is preferably 6 mm to 15 mm, preferably 8 mm to 12 mm, particularly preferably 10 mm. The selected parameters provide the surface of the aluminum alloy strip or sheet with a nearly identical surface finish to a brushed steel.

According to a further embodiment of the cladding sheet, the cladding sheet has an anodized layer with a thickness of 15 μm to 30 μm, preferably 18 μm to 22 μm or 20 μm to 25 μm. It has been shown that the previously used anodized layers of 10 .mu.m thickness are not sufficient to ensure sufficient corrosion protection and a permanently attractive appearance in the application range of the exterior facades. If facade panels are used with an anodized layer with a thickness of 18 to 22 .mu.m, a cladding sheet or strip optimized in terms of manufacturing costs can be provided, while at the same time the surface appearance on exterior facades is constant. Also advantageous is an Eloxalschichtdicke of more than 20 microns to 25 microns, because they ensure at low overhead in the production of a further improved corrosion protection and thus improved longevity of the facade panels, especially in high air pollution. Eloxal layers with more than 30 microns thickness, however, again show a lower protection. The Fasssadenbleche or bands are then ideally suited for an external facade.

Finally, the facade sheet can be additionally colored during the anodization, so that even colored optics can be provided.

The cladding sheet or strip preferably consists of an aluminum alloy of the type AA 5005 with a maximum of 0.30% by weight. Si, at most 0.7 wt.% Fe, at most 0.20 wt.% Cu, at most 0.20 wt.% Mn, 0.50 wt.% To 1.1 wt 0.10% by weight of Cr, at most 0.25% by weight of Zn, and unavoidable impurities of at most 0.05% by weight individually and in total not more than 0.15% by weight. This aluminum alloy provides sufficient strength with good corrosion resistance and can be easily processed into a cladding sheet or strip.

• ein Walzbarren aus Aluminium oder einer Aluminiumlegierung vom Typ AA 5005 wird gegossen,
• der Walzbarren wird skalpiert, warm- und anschließend kaltgewalzt, wobei im letzten Kaltwalzstich der Abwalzgrad 15 % bis 30 % beträgt und die Arbeitswalzen eine Oberflächenstruktur aufweisen, welche eine mittlere Rauigkeit R_a von 1,2 µm bis 1,7 µm mit einer Rautiefe R_z von 7 bis 12 µm auf der Bandoberfläche erzeugen.

According to a second teaching of the present invention, the object is achieved by a method comprising the following method steps:

• a rolling billet of aluminum or an aluminum alloy of type AA 5005 is cast,
• the rolling ingot is scalped, hot-rolled and then cold-rolled, the degree of rolling being 15% to 30% in the last cold-rolling pass and the work rolls having a surface structure which has an average roughness R _a of 1.2 μm to 1.7 μm with a roughness R _z from 7 to 12 microns on the strip surface produce.

It has been found that, in particular, the production of the strip or sheet by casting a rolled bar and hot rolling of the rolled bar and subsequent cold rolling of the hot strip, a homogeneous surface roughness on the finished facade panel or facade tape can be achieved. As already stated above, the cladding sheet produced from a corresponding strip not only has sufficient strength and lighter weight than a steel sheet, but also a very similar one Surface appearance. In addition, a very good transfer of the surface structure of the work rolls on the aluminum alloy strip in the last cold roll pass ensures a rolling degree of preferably 20% in the last cold roll pass.

If the surface structure produced on the belt has a stroke length of 6 to 15 mm, preferably 8 to 12 mm and particularly preferably 10 mm, a surface very similar to the brushed steel can be produced in the belt.

According to a further variant of the method, only one work roll is used in the last cold rolling pass, which has a surface structure having an average roughness R _a of 1.2 microns to 1.7 microns with a mean roughness R _z of 7 .mu.m to 12 .mu.m on the Ribbon surface generated. In this case, a distinction can be clearly made between the inner side and the outward-facing, facade-forming side of the facade panel.

The aluminum strip thus produced is preferably reshaped and then first, i. anodized in a reformed condition so as not to damage the anodized layer during forming.

As already stated above, the formed facade sheet is anodized with an anodizing layer thickness of 15 to 30 .mu.m, preferably 18 to 22 .mu.m or 20 .mu.m to 25 .mu.m, to meet the specific requirements of the environment of the cladding.

Fig. 1

eine schematische Ansicht einer Außenfassade eines Gebäudes,

Fig. 2

eine Schnittansicht eines Ausführungsbeispiels eines Fassadenblechs und

Fig. 3a) b)

eine schematische perspektivische Ansicht auf die Arbeitswalzen von zwei verschiedenen Kaltwalzgerüsten zur Erzeugung der Oberflächenstruktur des Fassadenblechs.

In addition, the invention will be explained with reference to embodiments in conjunction with the drawings. The drawing shows in

Fig. 1

a schematic view of an external facade of a building,

Fig. 2

a sectional view of an embodiment of a facade panel and

Fig. 3a) b)

a schematic perspective view of the work rolls of two different cold rolling stands for producing the surface structure of the facade sheet.

Fig. 1 shows in a highly schematic perspective view of an outer facade 1 of a building, which is clad with facade panels 2 according to the invention. The facade panels are made of an aluminum alloy of the type AA 5005 and have a thickness of more than 2 mm to a maximum of 4 mm, preferably 2.5 to 4 mm in thickness.

Due to the sheet thickness and the resulting low weight, the aluminum sheets according to the invention can be easily attached to a facade and also provide sufficient strength, for example, caused by wind load forces.

The surface of the facade panels 2 has been produced by the method according to the invention and has a surface appearance very similar to a brushed steel surface. The surface of the cladding sheet has an average roughness R _a of 1.2 microns to 1.7 microns, wherein the roughness R _z of 7 microns to 12 microns measured according to DIN EN ISO 4287.

In addition, the stroke length of the roughness structure is 8 mm to 12 mm, preferably the stroke length is 10 mm. Nevertheless, the facade panel 2 is much lighter than a brushed steel sheet. This in FIG. 2 Facade panel 2 shown in a sectional view has an anodized layer of 15 μm to 30 μm, preferably 18 μm to 22 μm. This anodized coating ensures that the aluminum alloy sheet is corrosion-resistant and at the same time can have an individual color. An improved corrosion protection can be achieved by an preferably 20 μm to 25 μm thick anodized layer.

Painting this facade sheet is not necessary because it is extremely corrosion resistant. In addition, it can be colored during the anodization, wherein the color penetrates into the pores remaining in the anodized layer and remains there. The facade panel 2 according to the invention is also significantly lighter than a running in steel, brushed facade panel.

Since a forming process can possibly damage the anodized layer, the anodized layer is preferably applied after the forming of the sheet or strip.

The FIGS. 3a) and 3b 3) show, in a schematic, perspective view, the work rolls 3, 3 ', 4, 4' of the cold rolling stand of the last cold rolling pass, which introduce the surface structure into the aluminum alloy strip 5, 5 'and bring it to a final thickness of more than 2 mm to 4 mm, preferably cold rolled to 2.5 mm to 4 mm. In contrast to the work rolls 3, 4 in Fig. 3a ) points in Fig. 3b ) only one work roll 3 'the necessary surface structure for the facade sheet on. The sheet thus produced therefore has a clearly visible, provided with the surface structure preferred side for the facade. A process-reliable impression of the surface structure in the strip is achieved by a rolling degree of 15% to 30%, preferably 20% in the last cold-rolled pass.

Claims (8)

1. Facade plate or strip consisting of aluminium or an aluminium alloy of the type AA 5005, wherein the facade plate has a thickness of from more than 2 mm to at most 4 mm and the surface of the facade plate has an average roughness R_a of from 1.2 µm to 1.7 µm with a roughness depth R_z of from 7 µm to 12 µm measured according to DIN EN ISO 4287.
2. Facade plate or strip according to Claim 1, characterised in that the line length of the roughness structure is from 6 mm to 15 mm.
3. Facade plate or strip according to Claim 1 or 2, characterised in that the aluminium strip or plate comprises an anodised layer having a thickness of from 15 µm to 30 µm, preferably a thickness of from 18 µm to 22 µm or from 20 µm to 25 µm.
4. Method for producing a facade plate or strip according to any one of Claims 1 to 3, characterised in that

   - a rolling ingot of aluminium or of an aluminium alloy of the type AA 5005 is cast,

   - the scalped rolling ingot is hot-rolled and subsequently cold-rolled to a final thickness of from more than 2 mm to 4 mm, the degree of rolling reduction in the last cold-rolling pass being from 15% to 30%, preferably 20 % and the working rolls of the last cold-rolling pass having a surface structure which generate an average roughness R_a of from 1.2 µm to 1.7 µm with a roughness depth R_z of from 7 µm to 12 µm on the strip surface.
5. Method according to Claim 4, characterised in that the line length of the roughness structure generated on the cold-rolled strip is from 6 mm to 15 mm.
6. Method according to Claim 4 or 5, characterised in that only one working roll has a surface structure which generates an average roughness R_a of from 1.2 µm to 1.7 µm with an average roughness depth R_z of from 7 µm to 12 µm on the strip surface.
7. Method according to any one of Claims 4 to 6, characterised in that plates are cut from the cold-rolled aluminium alloy strip, shaped into facade plates and anodised after the shaping.
8. Method according to any one of Claims 4 to 7, characterised in that the shaped facade plate is anodised with an anodised layer thickness of from 15 µm to 30 µm, preferably from 18 µm to 22 µm or from 20 µm to 25 µm.

Images