EP1166905B1 - Method for producing an aluminium sheet and aluminium sheet - Google Patents
Method for producing an aluminium sheet and aluminium sheet Download PDFInfo
- Publication number
- EP1166905B1 EP1166905B1 EP01202510A EP01202510A EP1166905B1 EP 1166905 B1 EP1166905 B1 EP 1166905B1 EP 01202510 A EP01202510 A EP 01202510A EP 01202510 A EP01202510 A EP 01202510A EP 1166905 B1 EP1166905 B1 EP 1166905B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- aluminium sheet
- microns
- process step
- range
- surface roughness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Revoked
Links
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 65
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 65
- 239000004411 aluminium Substances 0.000 title claims abstract description 64
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 5
- 238000000034 method Methods 0.000 claims abstract description 43
- 230000003746 surface roughness Effects 0.000 claims abstract description 27
- 238000005097 cold rolling Methods 0.000 claims abstract description 5
- 238000002048 anodisation reaction Methods 0.000 claims description 16
- 229910000838 Al alloy Inorganic materials 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims 1
- 239000010410 layer Substances 0.000 description 14
- 239000000463 material Substances 0.000 description 14
- 239000011324 bead Substances 0.000 description 13
- 239000011521 glass Substances 0.000 description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000005422 blasting Methods 0.000 description 7
- 239000011247 coating layer Substances 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 238000007788 roughening Methods 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 239000012670 alkaline solution Substances 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000002103 nanocoating Substances 0.000 description 3
- 239000002985 plastic film Substances 0.000 description 3
- 229920006255 plastic film Polymers 0.000 description 3
- 230000001681 protective effect Effects 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000001117 sulphuric acid Substances 0.000 description 3
- 235000011149 sulphuric acid Nutrition 0.000 description 3
- 238000000137 annealing Methods 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000011265 semifinished product Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 241000219198 Brassica Species 0.000 description 1
- 235000003351 Brassica cretica Nutrition 0.000 description 1
- 235000003343 Brassica rupestris Nutrition 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 235000007688 Lycopersicon esculentum Nutrition 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 240000003768 Solanum lycopersicum Species 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- QKSKPIVNLNLAAV-UHFFFAOYSA-N bis(2-chloroethyl) sulfide Chemical compound ClCCSCCCl QKSKPIVNLNLAAV-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 238000010411 cooking Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 235000010460 mustard Nutrition 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 235000015067 sauces Nutrition 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
- B21B1/227—Surface roughening or texturing
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B2003/001—Aluminium or its alloys
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/005—Rolls with a roughened or textured surface; Methods for making same
Definitions
- the invention relates to a method for producing an aluminium sheet with a decorative surface structure and to a curved aluminium sheet (see e.g. JP-A 404 1003).
- Sheet material such as for example of aluminium, aluminium alloys and stainless steel, with a decorative surface structure is used, inter alia, for domestic appliances, such as for example the outside of refrigerators and freezers, and for the front panels of audiovisual equipment.
- Sheet material of this type has a shiny metallic or if desired a matt metallic appearance and, if desired, can be provided with an organic covering layer for further decoration or protection.
- a typical shiny metallic surface structure is generally obtained by blasting the sheet material with, for example, glass beads or stainless steel shot.
- One drawback of a surface structure obtained by blasting with beads is that the sheet material is handled in batches and sometimes even by hand, and consequently is rather expensive.
- an end product such as for example a refrigerator door
- this product is manually or semi-automatically provided with the desired shiny or matt peened surface structure.
- the existing thicknesses for outer sides of domestic materials do not allow, for example, manual blasting with glass beads, on account of the risk of deformation caused by the blasting pressure, and furthermore there is a risk of non-uniformity caused by the manual blasting.
- a desired aluminium sheet material of this type must be less expensive than the cost of sheet material with a surface structure obtained by treatment by means of blasting, in particular with glass beads.
- the result is a method which can be operated continuously and on an industrial scale to produce aluminium sheet with the desired decorative surface structure described above on at least one side of the aluminium sheet, which decorative surface structure closely to very closely approximates to that of the known finish obtained using glass beads, while the cost price of the finished product is considerably lower than that of aluminium sheet material which is blasted in batches or by hand.
- a cold-rolled aluminium sheet which is provided typically has a surface roughness Ra in a range from 0.2 to 0.6 microns, measured in accordance with DIN 4768.
- Mill finish is a term which is known to the person skilled in the art and refers to microscopically visible thin lines oriented substantially in the rolling direction.
- the method obtained results in a relatively inexpensive semi-finished product on a coil with a desired decorative surface structure, which semi-finished product can then be used to produce end products, such as for example doors for domestic appliances, which then require no further manual treatment.
- the decorative surface structure of the known finish obtained using glass beads is closely approximated to with a surface roughness of up to Ra 3.0 microns
- the roughness Ra which is applied in process step (b) is preferably at most 2.5 microns. Below this value, the decorative surface structure very closely approximates to that of the known finish obtained using glass beads.
- the surface roughness is applied to the aluminium sheet by means of rollers with a non-deterministic structure, more preferably by means of electro-discharge texturing rollers, or EDT rollers for short.
- a desired surface structure to be applied, for example, to a coil of aluminium sheet material continuously and on an industrial scale.
- the application of the desired surface roughness by means of EDT rollers is achieved, inter alia, through the fact that the original mill finish on the cold-rolled aluminium sheet of the desired final thickness has completely or almost completely disappeared.
- the desired result is obtained in one or more light cold-rolling passes. This changes the thickness of the final aluminium sheet by less than 15%, and typically about up to 6%, with respect to the cold-rolled aluminium starting material.
- the surface roughness is applied to the aluminium sheet by means of rollers with a non-deterministic structure which are produced with the aid of the precision texturing process.
- a small quantity of chromium is applied to the roller in the form of circular or spherical spots.
- the roller with the non-deterministic structure has a surface roughness Ra in a range between 2 and 6 microns, preferably between 3 and 6 microns, measured in accordance with DIN 4768.
- a desired decorative surface structure within the desired Ra range is achieved on the aluminium sheet.
- the roughened aluminium sheet in a process step (c) is provided with a coating layer, for example by means of painting, in which case the coating layer is a layer of paint, or by means of nano-coating, in which case the coating layer is a nano-coating, or by means of anodization, in which case the coating layer is an anodized layer.
- the nano-coating may comprise a sol-gel process.
- the choice of thickness and the type of layer is determined by the end use of the aluminium sheet.
- the decorative surface structure can be attained or even adapted to the desired appearance of the peened surface structure.
- the surface can in this way be provided with a desired colour.
- the surface of the roughened aluminium sheet is provided with better protection against scratches and other external influences by the coating layer.
- the roughened aluminium sheet is anodized in a process step (c) or is provided with an anodized layer with a thickness in a range of up to 15 microns, more preferably in a range from 3 to 15 microns, by means of anodization.
- the anodization may be carried out in the customary continuous way on an industrial scale by passing strip material continuously through an anodization bath. Colour anodization is also possible. It has been found that the continuously produced and anodized strip material can also undergo further operations, such as for example punching, bending and light deep-drawing without excessive cracking of the anodized layer which has been applied.
- anodization over, for example, painting offers very good protection against external chemical influences, such as against spilt cooking ingredients such as tomato sauce and mustard.
- the aluminium sheet after the application of the desired surface roughness and before the anodization, is pickled in a process step (b1).
- the aluminium sheet may be chemically or electrochemically pickled in an alkaline or acidic medium. More preferably, the aluminium sheet is pickled in an alkaline medium.
- the intermediate pickling prior to anodization leads to the final sheet material acquiring a surface structure which is somewhat more matt in terms of appearance. For a number of applications of the aluminium sheet obtained using the method according to the invention, this is a highly desirable property of the sheet material.
- a further advantage is that a pickling treatment is relatively simple to incorporate in a continuous industrial production line which is suitable for the method according to the invention.
- the cold-rolled aluminium sheet is brought into a strengthened state, also known as an H temper by the person skilled in the art.
- H temper also known as an H temper by the person skilled in the art.
- This designation applies to products which have been cold-formed after annealing or after hot-forming or to a combination of strengthening and annealing or stabilizing for hardness, in order to obtain the specific mechanical properties.
- Typical examples which, however, do not limit the invention are an H14 and an H22 temper. It has been found that in particular wrought aluminium alloys with an H temper are very suitable for the application, efficiently and reproducibly on an industrial scale, of the desired surface roughness by cold-rolling, and in particular by EDT rolling.
- the invention is also embodied by a curved aluminium sheet part, such as for example the door of a refrigerator or a freezer or the housing of a remote control for audiovisual equipment, produced from an aluminium sheet obtained using the method according to the invention.
- Aluminium sheet made from the AA5754 alloy in an H temper with a thickness of 0.7 mm on an industrial scale is provided with a surface roughness Ra of 1.35 microns, measured in accordance with DIN 4768, using an industrial EDT roller.
- the EDT roller used in this example has a surface roughness Ra of approximately 2.5 microns.
- the roughened aluminium sheet is then pickled lightly in an alkaline solution based on sodium hydroxide, and is then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns.
- the final surface roughness Ra of the aluminium sheet obtained was 1.31 microns.
- the aluminium sheet obtained is then provided with a protective plastic film and was then bent to form a door panel for a refrigerator.
- the final surface of the door panel provided a very good approximation to the appearance of a finish obtained using glass beads.
- Gloss measurements were also carried out at an angle of 60°, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 175.4 and 25.6 gloss units, respectively.
- Aluminium sheet produced from the AA5005 alloy in an H temper with a thickness of 0.5 mm on an industrial scale was provided with a surface roughness Ra of 1.53 microns, measured in accordance with DIN 4768, using an industrial EDT roller.
- the roughened aluminium sheet was then pickled very lightly in an alkaline solution based on sodium hydroxide and was then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns.
- the final surface roughness Ra of the aluminium sheet obtained was 1.52 microns.
- the aluminium sheet obtained was then provided with a protective plastic film and was then bent to form a panel for a remote control.
- the final surface of the remote control provided a very close approximation to the appearance of a finish obtained using glass beads.
- Gloss measurements at an angle of 60° were once again carried out, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 182.2 and 23.1 gloss units, respectively.
- Aluminium sheet which was produced from the AA5754 alloy in an H temper with a thickness of 0.7 mm on an industrial scale was provided with a surface roughness Ra of 2.1 microns, measured in accordance with DIN 4768, using an industrial EDT roller.
- the EDT roller used in this example has a surface roughness Ra of approximately 3.8 microns.
- the roughened aluminium sheet was pickled lightly in an alkaline solution based on sodium hydroxide and was then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns.
- the ultimate surface roughness Ra of the aluminium sheet obtained was 2.0 microns.
- the aluminium sheet obtained was then provided with a protective plastic film and was then bent to form a door panel of a refrigerator.
- the ultimate surface of the door panel provided a very close approximation to the appearance of a finish obtained using glass beads.
- Gloss measurements at an angle of 60° were also carried out, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 128.3 and 22.7 gloss units, respectively.
- aluminium sheets were provided with a surface roughness of Ra 0.9 micron and Ra 1.0 micron with the aid of EDT rollers. Visual inspection revealed that these sheets do not have a surface structure which approximates the desired surface structure which would be obtained by blasting with glass beads.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
- Laminated Bodies (AREA)
- Shaping Metal By Deep-Drawing, Or The Like (AREA)
Abstract
Description
- The invention relates to a method for producing an aluminium sheet with a decorative surface structure and to a curved aluminium sheet (see e.g. JP-A 404 1003).
- The values which are given in this patent application for surface roughness Ra are all measured in accordance with DIN 4768.
- Sheet material, such as for example of aluminium, aluminium alloys and stainless steel, with a decorative surface structure is used, inter alia, for domestic appliances, such as for example the outside of refrigerators and freezers, and for the front panels of audiovisual equipment. Sheet material of this type has a shiny metallic or if desired a matt metallic appearance and, if desired, can be provided with an organic covering layer for further decoration or protection. A typical shiny metallic surface structure is generally obtained by blasting the sheet material with, for example, glass beads or stainless steel shot. One drawback of a surface structure obtained by blasting with beads is that the sheet material is handled in batches and sometimes even by hand, and consequently is rather expensive. Furthermore, it is often the case that an end product, such as for example a refrigerator door, is produced, and then this product is manually or semi-automatically provided with the desired shiny or matt peened surface structure. Moreover, the existing thicknesses for outer sides of domestic materials do not allow, for example, manual blasting with glass beads, on account of the risk of deformation caused by the blasting pressure, and furthermore there is a risk of non-uniformity caused by the manual blasting.
- There is a market demand for aluminium sheet material with a surface structure which approximates the surface structure of a glass bead finish as closely as possible. A desired aluminium sheet material of this type must be less expensive than the cost of sheet material with a surface structure obtained by treatment by means of blasting, in particular with glass beads.
- It is an object of the invention to provide a method for producing an aluminium sheet with a desired decorative surface structure as described above applied to at least one side of the aluminium sheet.
- This problem is solved by the features of claim 1.
- The result is a method which can be operated continuously and on an industrial scale to produce aluminium sheet with the desired decorative surface structure described above on at least one side of the aluminium sheet, which decorative surface structure closely to very closely approximates to that of the known finish obtained using glass beads, while the cost price of the finished product is considerably lower than that of aluminium sheet material which is blasted in batches or by hand. A cold-rolled aluminium sheet which is provided typically has a surface roughness Ra in a range from 0.2 to 0.6 microns, measured in accordance with DIN 4768. Furthermore, the method according to the invention ensures that the original mill finish has completely or almost completely disappeared. Mill finish is a term which is known to the person skilled in the art and refers to microscopically visible thin lines oriented substantially in the rolling direction. Furthermore, the method obtained results in a relatively inexpensive semi-finished product on a coil with a desired decorative surface structure, which semi-finished product can then be used to produce end products, such as for example doors for domestic appliances, which then require no further manual treatment.
- Although the decorative surface structure of the known finish obtained using glass beads is closely approximated to with a surface roughness of up to Ra 3.0 microns, the roughness Ra which is applied in process step (b) is preferably at most 2.5 microns. Below this value, the decorative surface structure very closely approximates to that of the known finish obtained using glass beads.
- It has been found that the appearance of the finish obtained using glass beads is still very closely approximated to in particular with surface roughness values of over Ra 1.8 microns.
- In one embodiment of the method according to the invention, the surface roughness is applied to the aluminium sheet by means of rollers with a non-deterministic structure, more preferably by means of electro-discharge texturing rollers, or EDT rollers for short. This allows a desired surface structure to be applied, for example, to a coil of aluminium sheet material continuously and on an industrial scale. Furthermore, the application of the desired surface roughness by means of EDT rollers is achieved, inter alia, through the fact that the original mill finish on the cold-rolled aluminium sheet of the desired final thickness has completely or almost completely disappeared. During the application of the surface structure by means of EDT rollers, the desired result is obtained in one or more light cold-rolling passes. This changes the thickness of the final aluminium sheet by less than 15%, and typically about up to 6%, with respect to the cold-rolled aluminium starting material.
- In another embodiment of the method according to the invention, the surface roughness is applied to the aluminium sheet by means of rollers with a non-deterministic structure which are produced with the aid of the precision texturing process. In this process, a small quantity of chromium is applied to the roller in the form of circular or spherical spots.
- In an embodiment according to the method, the roller with the non-deterministic structure has a surface roughness Ra in a range between 2 and 6 microns, preferably between 3 and 6 microns, measured in accordance with DIN 4768. Depending on the reduction in the thickness of the aluminium sheet which is employed during the roughening in one or more cold-rolling passes, in this way a desired decorative surface structure within the desired Ra range is achieved on the aluminium sheet.
- In one embodiment of the method according to the invention, in a process step (c) the roughened aluminium sheet is provided with a coating layer, for example by means of painting, in which case the coating layer is a layer of paint, or by means of nano-coating, in which case the coating layer is a nano-coating, or by means of anodization, in which case the coating layer is an anodized layer. The nano-coating may comprise a sol-gel process.
- The choice of thickness and the type of layer is determined by the end use of the aluminium sheet. Depending on the thickness and the type of layer, the decorative surface structure can be attained or even adapted to the desired appearance of the peened surface structure. Alternatively, the surface can in this way be provided with a desired colour. Moreover, the surface of the roughened aluminium sheet is provided with better protection against scratches and other external influences by the coating layer.
- In an embodiment of the method according to the invention, the roughened aluminium sheet is anodized in a process step (c) or is provided with an anodized layer with a thickness in a range of up to 15 microns, more preferably in a range from 3 to 15 microns, by means of anodization. The anodization may be carried out in the customary continuous way on an industrial scale by passing strip material continuously through an anodization bath. Colour anodization is also possible. It has been found that the continuously produced and anodized strip material can also undergo further operations, such as for example punching, bending and light deep-drawing without excessive cracking of the anodized layer which has been applied. Despite the application of a thin anodized layer, the surface roughness applied remains within the given range, and therefore the desired decorative surface structure is also retained. Since it is no longer necessary for a product to be anodized in batches after deformation, there is a considerable reduction in cost of the end product.
- Another advantage of anodization over, for example, painting is that the anodized layer obtained by anodization offers very good protection against external chemical influences, such as against spilt cooking ingredients such as tomato sauce and mustard.
- In one embodiment of the method according to the invention, the aluminium sheet, after the application of the desired surface roughness and before the anodization, is pickled in a process step (b1). The aluminium sheet may be chemically or electrochemically pickled in an alkaline or acidic medium. More preferably, the aluminium sheet is pickled in an alkaline medium. The intermediate pickling prior to anodization leads to the final sheet material acquiring a surface structure which is somewhat more matt in terms of appearance. For a number of applications of the aluminium sheet obtained using the method according to the invention, this is a highly desirable property of the sheet material. A further advantage is that a pickling treatment is relatively simple to incorporate in a continuous industrial production line which is suitable for the method according to the invention.
- In principle, all wrought aluminium alloys which can be treated successfully by means of anodization can be processed in the method according to the invention. However, it has been found that the aluminium alloys which cannot be heat-treated can be processed more successfully than the aluminium alloys which can be heat-treated.
- Very good results are obtained with the method according to the invention if an aluminium alloy selected from the Aluminium Association (AA)1xxx series, (AA)3xxx series, (AA)5xxx series and (AA)6xxx series is used for the cold-rolled aluminium sheet. It is preferable to select a wrought aluminium alloy which cannot be heat-treated from the AA5xxx series. These are the aluminium alloys in which magnesium is the most important alloying element. Typical examples which, however, do not limit the invention are the alloys AA5005 and AA5754.
- More preferably, the cold-rolled aluminium sheet is brought into a strengthened state, also known as an H temper by the person skilled in the art. This designation applies to products which have been cold-formed after annealing or after hot-forming or to a combination of strengthening and annealing or stabilizing for hardness, in order to obtain the specific mechanical properties. Typical examples which, however, do not limit the invention are an H14 and an H22 temper. It has been found that in particular wrought aluminium alloys with an H temper are very suitable for the application, efficiently and reproducibly on an industrial scale, of the desired surface roughness by cold-rolling, and in particular by EDT rolling.
- The invention is also embodied by a curved aluminium sheet part, such as for example the door of a refrigerator or a freezer or the housing of a remote control for audiovisual equipment, produced from an aluminium sheet obtained using the method according to the invention.
- The invention will now be explained with reference to a number of examples, which do not restrict the invention.
- Aluminium sheet made from the AA5754 alloy in an H temper with a thickness of 0.7 mm on an industrial scale is provided with a surface roughness Ra of 1.35 microns, measured in accordance with DIN 4768, using an industrial EDT roller. The EDT roller used in this example has a surface roughness Ra of approximately 2.5 microns. The roughened aluminium sheet is then pickled lightly in an alkaline solution based on sodium hydroxide, and is then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns. The final surface roughness Ra of the aluminium sheet obtained was 1.31 microns. The aluminium sheet obtained is then provided with a protective plastic film and was then bent to form a door panel for a refrigerator. The final surface of the door panel provided a very good approximation to the appearance of a finish obtained using glass beads. Gloss measurements were also carried out at an angle of 60°, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 175.4 and 25.6 gloss units, respectively.
- Aluminium sheet produced from the AA5005 alloy in an H temper with a thickness of 0.5 mm on an industrial scale was provided with a surface roughness Ra of 1.53 microns, measured in accordance with DIN 4768, using an industrial EDT roller. The roughened aluminium sheet was then pickled very lightly in an alkaline solution based on sodium hydroxide and was then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns. The final surface roughness Ra of the aluminium sheet obtained was 1.52 microns. The aluminium sheet obtained was then provided with a protective plastic film and was then bent to form a panel for a remote control. The final surface of the remote control provided a very close approximation to the appearance of a finish obtained using glass beads. Gloss measurements at an angle of 60° were once again carried out, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 182.2 and 23.1 gloss units, respectively.
- Aluminium sheet which was produced from the AA5754 alloy in an H temper with a thickness of 0.7 mm on an industrial scale was provided with a surface roughness Ra of 2.1 microns, measured in accordance with DIN 4768, using an industrial EDT roller. The EDT roller used in this example has a surface roughness Ra of approximately 3.8 microns. Then, the roughened aluminium sheet was pickled lightly in an alkaline solution based on sodium hydroxide and was then provided, in a sulphuric acid solution, with an anodized layer with a thickness of 5 microns. The ultimate surface roughness Ra of the aluminium sheet obtained was 2.0 microns. The aluminium sheet obtained was then provided with a protective plastic film and was then bent to form a door panel of a refrigerator. The ultimate surface of the door panel provided a very close approximation to the appearance of a finish obtained using glass beads. Gloss measurements at an angle of 60° were also carried out, in accordance with ASTM D-523, on the cold-rolled aluminium sheet after the roughening with the aid of the EDT roller and after the anodization. The results were 128.3 and 22.7 gloss units, respectively.
- For comparison purposes, aluminium sheets were provided with a surface roughness of Ra 0.9 micron and Ra 1.0 micron with the aid of EDT rollers. Visual inspection revealed that these sheets do not have a surface structure which approximates the desired surface structure which would be obtained by blasting with glass beads.
- It should be noted that it may be advantageous, in particular for a relatively thick anodized layer and/or substantial deformation operations carried out on the decorative aluminium sheet provided with the decorative surface structure to be curved or bent before the curved aluminium sheet is anodized, despite the higher costs associated with batchwise anodization. This has the advantage that the anodized layer cannot be damaged during the deformation.
Claims (12)
- Method for producing an aluminium sheet with a decorative surface structure on at least one side, comprising the successive process steps of:(a) providing a cold-rolled aluminium sheet of a desired thickness;(b) using cold-rolling to apply a surface roughness Ra to at least one side of the aluminium sheet, in a range from 1.2 to 3.0 microns measured in accordance with DIN 4768,
- Method according to Claim 1, characterized in that said anodized layer has a thickness in a range up to 15µm.
- Method according to Claim 2, characterized in that said anodized layer has a thickness in the range of 3 to 15µm.
- Method according to Claim 1 to 3, characterized in that during process step (b) the surface roughness is applied by means of rollers with a non-deterministic texture.
- Method according to Claim 4, characterized in that during process step (b) the surface roughness is applied by means of electro-discharge texturing (EDT) rollers.
- Method according to Claims 1 to 5, characterized in that after process step (b) and before process step (c) the aluminium sheet is pickled in a process step (b1).
- Method according to Claim 6, characterized in that during the process step (b1) the aluminium sheet is chemically or electrochemically pickled in an alkaline or acidic medium.
- Method according to one of Claims 1 to 7, characterized in that during process step (b) a surface roughness in a range of Ra 1.3 to 3.0 microns is applied, preferably in a range of Ra 1.5 to 3.0 microns, measured in accordance with DIN 4768.
- Method according to one of Claims 1 to 8, characterized in that the roughness Ra which is applied in process step (b) is at most 2.5 microns, measured in accordance with DIN 4768.
- Method according to claim 1, 2 or 3 characterized in that the surface roughness Ra applied in step (b) is over 1.8µm, measured in accordance with DIN 4768.
- Method according to one of the preceding Claims 1 to 10, characterized in that an aluminium alloy from the AA1xxx series, the AA3xxx series, the AA5xxx series or the AA6xxx series is selected for the composition of the aluminium sheet provided.
- Curved aluminium sheet obtained by the method according to one of Claims 1 to 11, having on at least one side a roughened surface of the aluminum sheet having a surface roughness Ra in the range 1.2 to 3.0 microns measured in accordance with DIN 4768 the curved aluminium sheet further characterized in having, on said roughened surface an anodization layer with a thickness in a range of up to 20 microns.
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1015568 | 2000-06-29 | ||
NL1015568 | 2000-06-29 | ||
NL1015921 | 2000-08-11 | ||
NL1015921 | 2000-08-11 |
Publications (4)
Publication Number | Publication Date |
---|---|
EP1166905A2 EP1166905A2 (en) | 2002-01-02 |
EP1166905A8 EP1166905A8 (en) | 2002-05-08 |
EP1166905A3 EP1166905A3 (en) | 2003-04-02 |
EP1166905B1 true EP1166905B1 (en) | 2005-10-05 |
Family
ID=26643193
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01202510A Revoked EP1166905B1 (en) | 2000-06-29 | 2001-06-29 | Method for producing an aluminium sheet and aluminium sheet |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1166905B1 (en) |
AT (1) | ATE305826T1 (en) |
DE (1) | DE60113772T2 (en) |
DK (1) | DK1166905T3 (en) |
ES (1) | ES2246997T3 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10345934B4 (en) * | 2002-10-18 | 2005-03-10 | Corus Aluminium Nv | Metal blank for molding and process for its production |
PT2665842E (en) * | 2011-01-17 | 2015-03-30 | Hydro Aluminium Rolled Prod | Exterior wall metal sheet made of aluminium having a high surface roughness |
ES2610971B1 (en) * | 2015-09-30 | 2018-02-09 | Acr Ii Aluminium Group Cooperatief U.A. | ALUMINUM SURFACE RECORDING PROCESS |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE634213A (en) * | 1961-07-17 | |||
DE3008679C2 (en) * | 1980-03-06 | 1983-08-18 | Vereinigte Metallwerke Ranshofen-Berndorf AG, 5282 Braunau am Inn, Oberösterreich | Deep-drawable sheet metal or strip made of non-ferrous metal or an alloy thereof, in particular made of aluminum, as well as a method for its production |
DE3705100A1 (en) * | 1987-02-18 | 1988-09-01 | Benecke Gmbh J | METHOD FOR PRODUCING A SURFACE STRUCTURE OF IMPELLING ROLLERS, AND PRINCING ROLLER PRODUCED BY THE METHOD |
JPH0441003A (en) * | 1990-06-07 | 1992-02-12 | Furukawa Alum Co Ltd | Exterior use aluminum or aluminum alloy plate and its manufacture |
-
2001
- 2001-06-29 EP EP01202510A patent/EP1166905B1/en not_active Revoked
- 2001-06-29 AT AT01202510T patent/ATE305826T1/en not_active IP Right Cessation
- 2001-06-29 DE DE60113772T patent/DE60113772T2/en not_active Revoked
- 2001-06-29 ES ES01202510T patent/ES2246997T3/en not_active Expired - Lifetime
- 2001-06-29 DK DK01202510T patent/DK1166905T3/en active
Also Published As
Publication number | Publication date |
---|---|
EP1166905A8 (en) | 2002-05-08 |
DK1166905T3 (en) | 2005-11-21 |
DE60113772D1 (en) | 2006-02-16 |
ES2246997T3 (en) | 2006-03-01 |
EP1166905A3 (en) | 2003-04-02 |
DE60113772T2 (en) | 2006-06-22 |
ATE305826T1 (en) | 2005-10-15 |
EP1166905A2 (en) | 2002-01-02 |
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