METHOD FOR PRODUCING MULTI-WALLED TUBES, AND MULTIWALLED TUBE

Abstract

The disclosure relates to a method for producing multi-walled tubes, in which a metal strip is rolled up to form the multi-walled tube. The metal strip has at least one steel layer, and at least one solder layer is applied to the steel layer. The solder layer consists at least in part of metal. According to the disclosure, the solder layer is applied to the steel layer by plasma coating.

Claims

1. A method for producing multi-walled tubes, in which a metal strip is rolled up to form the multi-walled tube, the metal strip having at least one steel layer, and at least one solder layer being applied to the steel layer, the solder layer consisting at least substantially of metal, wherein the solder layer is applied to the steel layer by plasma coating.

2. The method according to claim 1, wherein the solder layer consists of copper or substantially consists of copper.

3. The method according to claim 1, wherein the solder layer is applied to the steel layer without the interposition of a further metal layer.

4. The method according to claim 1, wherein the steel layer has a thickness of 100 to 600 μm.

5. The method according to claim 1, wherein the solder layer is applied to the steel layer by plasma coating with a thickness of 2 to 20 μm.

6. The method according to claim 1, wherein the steel layer is thicker than the solder layer by five times to ten times as thick as the solder layer.

7. The method according to claim 1, wherein the coating is applied without the use of cyanides and/or without the use of nickel.

8. The method according to claim 1, wherein the plasma coating is carried out at normal pressure or atmospheric pressure.

9. The method according to claim 1, wherein the plasma coating is carried out as a physical vapour deposition and/or as a chemical vapour deposition.

10. The method according to claim 1, wherein the material for the solder layer is supplied in a plasma coating device in powder form.

11. The method according to claim 1, wherein the material for the solder layer is converted into the gas phase in the plasma coating device and then deposited on the steel layer as a solder layer.

12. The method according to claim 1, wherein the metal strip consisting of at least the steel layer and the solder layer is rolled up to form a double-walled tube.

13. The method according to claim 1, wherein the steel layer is coated with the solder layer on both surfaces by means of plasma coating.

14. The method according to claim 1, wherein the wall layers of the multi-walled tube are soldered or joined to each other by heating.

15. A multi-walled tube produced using a method according to claim 1 having a rolled-up metal strip, wherein the metal strip has at least one steel layer and at least one solder layer applied to the steel layer by means of plasma coating.

16. The method according to claim 1, wherein the steel layer has a thickness of 200 to 400 μm.

17. The method according to claim 1, wherein the solder layer is applied to the steel layer by plasma coating with a thickness of 3 to 10 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosure is explained in more detail below with the aid of a drawing showing only one exemplary embodiment. In the figures:

[0019] FIG. 1 schematically shows a perspective diagram of a metal strip before being rolled up to form the multi-walled tube,

[0020] FIG. 2 schematically shows a section through a double-walled tube rolled up out of the metal strip, and

[0021] FIG. 3 schematically shows a schematic diagram of a plasma coating device preferably used to carry out the method according to the disclosure.

[0022] The figures illustrate a method according to the disclosure for producing multi-walled tubes 1. Preferably and in the exemplary embodiment (see in particular FIG. 2), a double-walled tube 1 is produced using the method according to the disclosure. To this end, a metal strip 2 is rolled up to form the double-walled tube 1. Expediently and in the exemplary embodiment, the metal strip has a steel layer 3 or steel strip. Preferably and in the exemplary embodiment, a solder layer 4 of copper is applied to this steel layer 3.

DETAILED DESCRIPTION

[0023] In the exemplary embodiment, the steel layer can have a thickness of 200 to 400 μm, and the solder layer 4 or copper layer can have a thickness of 3 to 10 μm. Preferably and in the exemplary embodiment, the steel layer 3 is much thicker than the solder layer 4 or copper layer. According to the disclosure, the coating with the solder layer 4 takes place without the interposition of a nickel layer as is known in the prior art.

[0024] According to the disclosure, the solder layer 4 or copper layer is applied to the steel layer 3 or steel strip by plasma coating. Expediently, the plasma coating is carried out at normal pressure or atmospheric pressure. Within the scope of the disclosure, the plasma coating takes place as a physical vapour deposition.

[0025] FIG. 3 shows a plasma coating device 5 suitable for the method according to the disclosure. FIG. 3 shows the electrode 6 of this plasma coating device 5 and the gas supply chamber 7. Within the scope of the disclosure, the material for the solder layer 4—in particular the copper material for the solder layer 4—is supplied in the plasma coating device 5 in powder form, more specifically, expediently and in the exemplary embodiment, is supplied through the duct 8 in powder form. Preferably and in the exemplary embodiment, the material for the solder layer 4—in particular the copper material for the solder layer 4—is converted into the gas phase in the plasma coating device 5 and then deposited on the steel layer 3 as a solder layer 4 or copper layer. The plasma jet 9 can also be seen in FIG. 3.

[0026] After the deposition of the solder layer 4, the coated metal strip 2 shown in FIG. 1 is obtained. This metal strip 2 is then preferably rolled up with the aid of rollers to form the double-walled tube 1 shown in FIG. 2. Within the scope of the disclosure, the tube 1 or the wall layers of the tube 1 are then soldered or joined to each other by heating. Expediently, this heating takes place in an induction furnace (not shown).

[0027] The production according to the disclosure of the multi-walled or double-walled tube 1 can advantageously be carried out without the use of cyanide-containing electrolyte baths and can advantageously also take place without the interposition of a nickel layer between the solder layer 4 and the steel layer 3.