PROCESS OF PRODUCING A NON-FERROUS METALLIC TUBE

Abstract

The invention relates to a process of producing a non-ferrous metallic tube, in which process comprises a casting stage, in which a cast tube having an outer diameter of 20-70 mm, preferably 35-55 mm and a wall thickness of 1.0-4.0 mm, preferably 2.0-3.0 mm, is casted from melt by continuous upward vertical casting process, and the casting stage is followed by at least two drawing stages. In the drawing stages drawing direction of the cast tube in at least two each other following drawing stages is opposite to each other.--

Claims

1. A process of producing a non-ferrous metallic tube, which comprises a casting stage, in which a cast tube having an outer diameter of 20-70 mm, is cast from melt by continuous upward vertical casting process, and the casting stage is followed by at least two drawing stages, which cast tube cast from melt by continuous upward vertical casting process has a wall thickness of 1.0-4.0 mm, wherein drawing direction of the cast tube in at least two drawing stages following each other is opposite to each other.

2. The process of producing a non-ferrous metallic tube according to claim 1, wherein the process has two to four drawing stages and that-the drawing direction of the cast tube in at least two drawing stages following each other is opposite to each other.

3. The process of producing a non-ferrous metallic tube according to claim 1, wherein the process comprises after the drawing stages an intermediate annealing stage and a cooling stage.

4. The process of producing a non-ferrous metallic tube according to claim 2, wherein the process further comprises an uncoiling stage before each drawing stage and before the intermediate annealing stage and coiling stages after the casting stage, after each drawing stage and after the cooling stage.

5. The process of producing a non-ferrous metallic tube according to claim 3, wherein degree of reduction of cross-section area of the cast tube in the drawing stages before the intermediate annealing is 40-70%.

6. The process of producing a non-ferrous metallic tube according to claim 3, wherein, grain size of the cast tube after the intermediate annealing stage of the process is 0.02-0.09 mm.

7. The process of producing a non-ferrous metallic tube according to claim 1, wherein the process is to produce tubes from copper, alloyed copper and copper alloys.

8. The process of producing a non-ferrous metallic tube according to claim 1, wherein the process is to produce tubes, for example even thin wall ACR-tubes, either plain or inner grooved, from copper, alloyed copper and copper alloys such as for example OF (oxygen-free) Cu (ASTM B170-99), and DHP (deoxidized, oxygen-free with a residual phosphorus content) Cu (SFS-EN 1652) and CuNi or from other non-ferrous metals.

9. The process of producing a non-ferrous metallic tube according to claim 8, wherein grain size of the cast tube of DHP Cu after the intermediate annealing stage of the process is at most 0.04 mm.

10. The process of claim 1, wherein the cast tube has an outer diameter of 33-55 mm.

11. The process of claim 1, wherein cast tube cast from melt by continues upward vertical casting process has a wall thickness is 2.0-3.0 mm.

12. The process of claim 5, wherein the reduction of the cross section area of the cast tube in the drawing stages before the intermediate annealing is 50-60%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In FIG. 1 is schematically shown an advantageous example of the process of producing a non-ferrous metallic tube in accordance with the invention,

[0023] In FIGS. 2A-2B is schematically shown an example of a drawing system suitable for the drawing stages of the process of producing a non-ferrous metallic tube in accordance with the invention and

[0024] In FIGS. 3A-3B is schematically shown another example of a drawing system suitable for the drawing stages of the process of producing a non-ferrous metallic tube in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0025] During the course of the following description relating to FIGS. 1 - 3B like numbers and signs will be used to identify like elements according to the different views which illustrate the invention and its advantageous examples. In the figures some repetitive reference signs have been omitted for clarity reasons.

[0026] In the example of FIG. 1 the process 10 of producing a non-ferrous metallic tube comprises main stages: casting 11, drawing - first stage 12, drawing - second stage 13, intermediate annealing 14 and cooling 15. Each of the main stages typically comprises corresponding coiling 11C, 12C, 13C, 15C and uncoiling stages 12UC, 13UC, 14UC. By the coiling and uncoiling stages any speed differences of the main stages in the process speed are evened out.

[0027] In the casting stage 11 a cast tube is cast from melt by upward continuous casting process followed by coiling 11C. Advantageously, in the casting a continuous casting nozzle assembly for upward vertical casting of a non-ferrous tube, which is suitable for uninterrupted casting, which nozzle assembly comprises a nozzle, a mandrel and a cooler, wherein surface roughness of at least part of the dwindling area of an inner surface of the nozzle is 3 - 5 Ra.

[0028] The drawing stage comprises two drawing stages to opposite directions: first drawing stage 12, in which the drawing is effected to the tube in one direction in its longitudinal direction, and second drawing stage 13, in which the drawing is effected to the tube in the opposite direction in view of the first drawing stage in its longitudinal direction. Before each of the drawing stages 12, 13 the tube is first uncoiled in corresponding uncoiling stage 12UC, 13UC and after each drawing stage 12, 13 the tube is coiled in the corresponding coiling stage 12C, 13C.

[0029] In the drawing stages 12, 13 advantageously a drawing system of examples in FIGS. 2A-2B or 3A-3B is used. The drawing is done in at least two stages in which drawing direction of the cast tube in two each other following drawing stages 12, 13 is opposite to each other.

[0030] After the drawing stages intermediate annealing 14 and cooling 15 stages follow. Before the intermediate annealing stage 14 the tube is coiled in corresponding uncoiling stage 14UC and after the cooling stage 15 the tube is correspondingly coiled in a coiling stage 15C. In the intermediate annealing stage 14 the cast tube is heat-treated, annealed, in order to achieve the desired final microstructure to the tube material. In the cooling stage 15 the tube is cooled and there after coiled in the coiling stage 15C for transfer to next steps of treatment or use.

[0031] In FIGS. 2A-2B is shown an example of a drawing system suitable for the drawing stages 12, 13 of the process of producing a non-ferrous metallic tube. In this example is shown a left-handed system. The rotation direction of the coil in the uncoiling stage 12UC; 13UC and in the coiling stage 12C; 13C is indicated by arrows S and the drawing direction of the tube T is indicated by the arrows D12; D13. Before the first drawing in the first direction D12 in the first drawing stage 12 the tube T is first uncoiled in rotation direction S in the first uncoiling stage 12UC. Then, the tube T is drawn in the first direction D12 in the first drawing stage 12. After the drawing in the first drawing stage 12 the tube T is coiled in the first coiling stage 12C.The coil is then moved, as shown by the dashed line X, to the second uncoiling stage 13UC. The uncoiling in the second uncoiling stage 13C is begun from the tube end at the outer circumference of the coil. Then, the tube T is drawn in the second drawing stage 13 in the second direction D13, opposite to the first direction D12. After the drawing in the second drawing stage 13 the tube T is coiled in the second coiling stage 13C.

[0032] In FIGS. 3A-3B is shown another example of a drawing system suitable for the drawing stages 12, 13 of the process of producing a non-ferrous metallic tube. In this example is shown a right-handed system. The rotation direction of the coil in the uncoiling stage 12UC; 13UC and in the coiling stage 12C; 13C is indicated by arrows S and the drawing direction of the tube T is indicated by the arrows D12; D13. Before the first drawing in the first direction D12 in the first drawing stage 12 the tube T is first uncoiled in rotation direction S in the first uncoiling stage 12UC. Then, the tube T is drawn in the first direction D12 in the first drawing stage 12. After the drawing in the first drawing stage 12 the tube T is coiled in the first coiling stage 12C.The coil is then moved, as shown by the dashed line X, to the second uncoiling stage 13UC. The uncoiling in the second uncoiling stage 13C is begun from the tube end at the outer circumference of the coil. Then, the tube T is drawn in the second drawing stage 13 in the second direction D13, opposite to the first direction D12. After the drawing in the second drawing stage 13 the tube T is coiled in the second coiling stage 13C.

[0033] In the examples of FIGS. 2A-2B and 3A-3B of the drawing systems two drawing machines are used, one for each drawing stage 12;13. The drawing stages 12; 13 can also be done in one and the same drawing machine.

[0034] In the description in the foregoing, although some functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments or examples, those features may also be present in other embodiments or examples whether described or not.

[0035] Above only some advantageous examples of the inventions have been described to which examples the invention is not to be narrowly limited and many modifications and alterations of the details of the invention are possible within the scope of the following claims.

TABLE-US-00001 Reference signs used in the drawing: 10 process 11 casting stage 12 drawing stage 1 13 drawing stage 2 14 intermediate annealing stage 15 cooling stage 11C, 12C, 13C, 15C coiling stage 12UC, 13UC, 14UC uncoiling stage D12, D13 drawing direction T tube S rotation direction