Continuous furnace for aluminum strips

Abstract

The present invention relates to a continuous furnace system for heat treating a metal component, in particular an aluminium strip. The continuous furnace system has a first heating unit, in which the metal component is heatable for solution annealing up to a first temperature in the range of from 350° C. to 700° C., a cooling unit, in which the metal component is coolable from 300° C. to 750° C. down to 70° C. to 250° C., and a second heating unit, in which the metal component is heatable up to from 150° C. to 290° C. The first heating unit, the cooling unit, and the second heating unit both have a common support structure, on which the first heating unit, the cooling unit, and the second heating unit are fixed together. Furthermore, the continuous furnace system has a common conveyor track, which extends through the first heating unit, the cooling unit, and the second heating unit, wherein the conveyor track is configured in such a way that the metal component is passable along the conveyor track in the conveying direction through the first heating unit, the cooling unit, and the second heating unit for heat treatment.

Claims

1. A continuous furnace system for heat treating a metal component, the continuous furnace system comprising: a first heating unit, in which the metal component is heatable for solution annealing up to a first temperature in a range from 300° C. to 750° C.; a cooling unit, in which the metal component is coolable from 300° C. to 750° C. down to 70° C. to 250° C.; a second heating unit, in which the metal component is heatable up to 150° C. to 290° C.; wherein the first heating unit, the cooling unit, and the second heating unit have a common support structure, to which the first heating unit, the cooling unit, and the second heating unit are fixed together; and a common conveyor track, which extends through the first heating unit, the cooling unit, and the second heating unit, wherein the conveyor track is configured in such a way that the metal component is passable through along the conveyor track in the conveying direction through the first heating unit, the cooling unit, and the second heating unit for heat treatment; wherein the conveyor track has floating nozzles at least in one section, and wherein the floatation nozzles are arranged to flow a fluid or air against an underside of the metal component so that the metal component is conveyable through the section in a floating manner in the conveying direction.

2. The continuous furnace system according to claim 1, wherein the conveyor track has rollers at least in one section, along which the metal component is movable in the conveying direction.

3. The continuous furnace system according to claim 1, wherein the first heating unit has a length along the conveying direction from 20 m to 120 m.

4. The continuous furnace system according to claim 1, wherein the cooling unit has a length along the conveying direction from 1 m to 50 m.

5. The continuous furnace system according to claim 1, wherein the second heating unit has a length along the conveying direction from 1 m to 50 m.

6. The continuous furnace system according to claim 1, wherein the first heating unit is configured to heat the metal component by fuel gas, by a contact heating, by an induction heating, by a convection heating, by an eddy current heating, by an electric heating register, by an infrared heating, or by a heat radiation heating.

7. The continuous furnace system according to claim 1, wherein the second heating unit is configured to heat the metal component by fuel gas, by a contact heating, by an induction heating, by a convection heating, by an eddy current heating, by an electric heating register, by an infrared heating or by a heat radiation heating.

8. The continuous furnace system according to claim 1, wherein the cooling unit has nozzles for a cooling medium for cooling the metal component.

9. The continuous furnace system according to claim 1, further having: a holding unit for maintaining a temperature from 70° C. to 250° C. of the metal component, wherein the holding unit is arranged between the cooling unit and the second heating unit, wherein the holding unit is coupled to the support structure, and wherein the conveyor track extends through the holding unit.

10. The continuous furnace system according to claim 9, wherein the holding unit has a length from 5 m to 25 m along the conveying direction.

11. The continuous furnace system according to claim 1, further having: a further cooling unit, in which the metal component is coolable from 150° C. to 270° C. down to 70° C. to 150° C., wherein the further cooling unit is arranged in the conveying direction after the second heating unit, wherein the further cooling unit is coupled to the support structure, and wherein the conveyor track extends through the further cooling unit.

12. The continuous furnace system according to claim 11, wherein the further cooling unit has a length along the conveying direction from 18 m to 22 m.

13. The continuous furnace system according to claim 1, wherein the conveyor track is configured in such a way that a conveying speed of the conveyor track is adjustable between 60 m/min and 90 m/min.

14. A continuous furnace system for heat treating a metal component, the continuous furnace system comprising: a first heating unit, in which the metal component is heatable for solution annealing up to a first temperature in a range from 300° C. to 750° C.; a cooling unit, in which the metal component is coolable from 300° C. to 750° C. down to 70° C. to 250° C.; a second heating unit, in which the metal component is heatable up to 150° C. to 290° C.; wherein the first heating unit, the cooling unit, and the second heating unit have a common support structure, to which the first heating unit, the cooling unit, and the second heating unit are fixed together; a common conveyor track, which extends through the first heating unit, the cooling unit, and the second heating unit, wherein the conveyor track is configured in such a way that the metal component is passable through along the conveyor track in the conveying direction through the first heating unit, the cooling unit, and the second heating unit for heat treatment; and a holding unit for maintaining a temperature from 70° C. to 250° C. of the metal component, wherein the holding unit is arranged between the cooling unit and the second heating unit, wherein the holding unit is coupled to the support structure, and wherein the conveyor track extends through the holding unit.

15. A continuous furnace system for heat treating a metal component, the continuous furnace system comprising: a first heating unit, in which the metal component is heatable for solution annealing up to a first temperature in a range from 300° C. to 750° C.; a cooling unit, in which the metal component is coolable from 300° C. to 750° C. down to 70° C. to 250° C.; a second heating unit, in which the metal component is heatable up to 150° C. to 290° C.; wherein the first heating unit, the cooling unit, and the second heating unit have a common support structure, to which the first heating unit, the cooling unit, and the second heating unit are fixed together; and a common conveyor track, which extends through the first heating unit, the cooling unit, and the second heating unit, wherein the conveyor track is configured in such a way that the metal component is passable through along the conveyor track in the conveying direction through the first heating unit, the cooling unit, and the second heating unit for heat treatment; wherein the conveyor track is configured in such a way that a conveying speed of the conveyor track is adjustable between 60 m/min and 90 m/min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a further explanation and a better understanding of the present invention, embodiment examples are described in the following in more detail with reference to the appended drawings, in which:

(2) FIG. 1 shows a schematic illustration of a continuous furnace system according to an exemplary embodiment of the present invention.

(3) FIG. 2 shows a time/temperature diagram, in which the temperature curves of a metal component within the continuous furnace system from FIG. 1 are reproduced.

(4) FIG. 3 shows a path/temperature diagram in which the temperature curves of a metal component along a distance within the continuous furnace system from FIG. 1 are reproduced.

(5) FIG. 4 and FIG. 5 show schematic path/temperature diagrams, in which exemplary temperature curves of a metal component during the passing through a continuous furnace system according to an exemplary embodiment of the present invention are reproduced.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(6) Same or similar components in different figures are provided with the same reference numerals. The representations in the figures are schematic.

(7) FIG. 1 shows a continuous furnace system 100 for heat treating a metal component 110, in particular an aluminium strip. FIG. 2 shows a time/temperature diagram, in which the temperature curves of a metal component within the continuous furnace system from FIG. 1 are reproduced. The continuous furnace system 100 may have a first heating unit 101, in which the metal component 110 may be heatable for solution annealing up to a first temperature in the range of from 350° C. to 700° C., a cooling unit 102, in which the metal component 110 may be coolable from 350° C. to 700° C. down to 70° C. to 250° C., and a second heating unit 103, in which the metal component 110 may be heatable up to 150° C. to 270° C. The first heating unit 101, the cooling unit 102 and the second heating unit 103 may have a common support structure 106, on which the first heating unit 101, the cooling unit 102 and the second heating unit 103 may be fixed together (or jointly). Furthermore, the continuous furnace system 100 may have a common conveyor track 107, which may extend through the first heating unit 101, the cooling unit 102, and the second heating unit 103, wherein the conveyor track 107 may be designed in such a way that the metal component 110 may be passable along the conveyor track 107 in the conveying direction 109 through the first heating unit 101, the cooling unit 102, and the second heating unit 103 for heat treatment.

(8) The continuous furnace system 100 may be a continuous heat treatment system, in which the metal component 110 may be guided along a conveying direction 109 continuously or sequentially through the heat treatment stages. Herein, the metal component 110 may be conveyed with contact, for example along rollers 108, or it may be conveyed in a floating state contactlessly (or without contact).

(9) The metal component 110 may in particular be an aluminum strip, which may be conveyed continuously through the continuous furnace system 100.

(10) The cold-rolled aluminum strip 110 may first be solution annealed in a heating zone I in the first heating unit 101 in order to achieve the required metallurgical conditions. The aluminium strip 110 may be transferred in a coil from a cold rolling mill to the first heating unit 101, for example a continuous annealing and solution heat treatment furnace.

(11) The heating of the aluminum strip 110 in the first heating unit 101 may be effected, for example, by blowing hot air through plural nozzle boxes onto the aluminum strip 110 in a vertical direction from above and below.

(12) The annealing heat treatment of the aluminium strip 110, may result in a recovery and recrystallization of the cold-rolled state with the resulting fine-grained microstructure in the metal component 110. During the solution heat treatment, in addition to annealing, also the main stability phase may be dissolved and the metal component 110 may be enriched with dissolved substances.

(13) The cooling unit 102 may be located in the cooling zone II, and may be arranged immediately after the first heating unit 101, so that the aluminium strip may be coolable from the corresponding exit temperature from the first heating unit 101 in the range of from 350° C. to 700° C. down to 70° C. to 250° C. In the exemplary temperature curve as shown in FIG. 2, the aluminium strip 110 may first be heated up to 550° C. in heating zone I and may then cooled down to 70° C. in cooling zone II.

(14) In the cooling unit 102, nozzle systems may also be arranged, through which a cooling fluid, such as for example air or water and/or an air/water mixture, may flow onto the aluminium strip 110.

(15) The strength of the aluminium strip 110 may be increased further by performing an anew reheating after the cooling unit 102 in the heating zone IV, within which the second heating unit 103 may be provided. In this process, the metal component may, after the cooling in the first cooling unit 102 and, for example, after a certain holding time in the holding zone III, be subjected to a heat treatment, until the aluminium strip 110 again may have a temperature of approximately 52° C. Due to a short duration of the heat treatment in the second heating unit 103 of, for example, 15 seconds to 30 seconds, the temperature-time profile may look like a spike (or peak). This is why it is called “spiking” heat treatment.

(16) The continuous furnace system 100 may further have a holding unit 104 in the holding zone III for holding (or maintaining) a temperature of 70° C. to 150° C. of the aluminium strip 110. The holding unit 104 may be arranged between the cooling unit 102 and the second heating unit 103, wherein the holding unit 104 may be coupled to the support structure 106, and wherein the conveyor track 107 may extend through the holding unit 104.

(17) During this holding time of, for example, 15 seconds to 3 minutes at a constant exit temperature, the dissolved substances (or solutes) and the vacancies (or holes, or voids) in the aluminium strip may begin to group and to develop into nuclei.

(18) Furthermore, the continuous furnace system 100 may have, in the further cooling zone V, a further cooling unit 105, in which the metal component may be coolable from 150° C. to 270° C. down to 70° C. to 150° C. The further cooling unit 105 may be arranged in the conveying direction 109 after the second heating unit 103, wherein the further cooling unit 105 may be coupled to the support structure 106, and wherein the conveyor track 107 may extend through the further cooling unit 105. After the further cooling unit 105, the aluminium strip 110 may be further processed or, if necessary, supplied to further heat treatment steps, such as for example the further holding zone VI and the further heating zone VII (see FIGS. 4 and 5).

(19) The first heating unit 101, the cooling unit 102, the holding unit 104, the second heating unit 103 as well as the further cooling unit 105 may be attached to a common support structure 106. The support structure 106 may consist for example of support beams, and may have for example a protective frame structure.

(20) The conveyor 107 may run continuously from the entry to (or inlet in) the continuous furnace system 100 to an end of the continuous furnace system 100. The conveyor track 107 may have rollers 108 at least in one section, along which the aluminium strip 110 may be movable in the conveying direction. In addition or alternatively, the conveyor track 107 may have floating nozzles at least in one section, wherein the floating nozzles may be arranged to flow a fluid, in particular air, against an underside of the aluminium strip 110 so that the aluminium strip 110 may be conveyable through the section in a floating manner in the conveying direction 109.

(21) FIG. 3 shows a path/temperature diagram, in which the temperature curves of a metal component 110 along a distance within the continuous furnace system 100 from FIG. 1 are shown. In the diagram shown in FIG. 3, the distance from the exit (or outlet) of the first heating unit 101 is shown, as well as the corresponding associated temperature curves. In the diagram shown, temperature curves are shown of aluminium strips 110, and which may have a thickness of 1 mm, which may pass through the continuous furnace system 100 along the conveying direction 109 at a speed of 78 m/min.

(22) The first heating unit 101, which is not shown in FIG. 3, may have a length of from 50 m to 65 m along the conveying direction 109. At the end of the first heating zone I, the aluminium strip thus may have a temperature of approx. 550° C.

(23) In the second cooling zone II, the aluminium strip 110 may be cooled from 550° C. down to 150° C. by the cooling unit 102. The cooling unit 102 may have a length of 12 m along the conveying direction 109.

(24) In holding zone III, the temperature of the aluminum strip 110 may be held approximately constant by the holding unit 104, wherein though a moderate cooling from 150° C. to 80° C. may take place. The holding unit 104 may have a length of approx. 14 m along the conveying direction 109.

(25) In heating zone IV, the temperature of the aluminium strip 110 may be heated by the second heating unit 103 up to from 80° C. to 250° C. The second heating unit 103 may have a length of approx. 13 m along the conveying direction 109.

(26) In the further cooling zone V, the temperature of the aluminum strip 110 may be cooled from 250° C. down to approx. 60° C. by the further cooling unit 105. The further cooling unit 105 may have a length of approx. 20 m along the conveying direction 109.

(27) FIG. 4 and FIG. 5 show schematic path/temperature diagrams, in which exemplary temperature curves of a metal component 110 during the passing through a continuous furnace system 100 according to an exemplary embodiment of the present invention are reproduced.

(28) In the path-temperature diagram in FIG. 4, a temperature curve is shown of a aluminium strip, which may be 1.2 mm thick, and which may pass through a continuous furnace system 100 according to the invention at a speed of 60 m/min.

(29) In the first heating zone I, the first heating unit 101 may be provided, which may heat the aluminium strip 110 up to approx. 550° C. and may maintain this temperature for approx. 10 seconds.

(30) Subsequently, the cooling zone II may begin, wherein in a first step, the temperature of the aluminum strip 110 may be adjusted from 550° C. to 300° C. and in a second step, the temperature may be adjusted from 300° C. to less than 80° C. at the exit of cooling zone II. For example, with a strip thickness of from 0.5 mm to 1.2 mm, a cooling rate of more than 50° C. per second may be achieved, and with a material thickness of the strip of from 1.3 mm to 4.2 mm, a cooling rate of more than 30° C. per second may be achieved.

(31) In the holding zone III, the temperature of the aluminium strip 110 may be held at approx. 80° C.

(32) In heating zone IV, the temperature of the aluminum strip 110 may be set to approximately 250° C. by the second heating unit 103.

(33) Subsequently, in the further cooling zone V, the temperature of the aluminum strip 110 may be cooled from 250° C. down to 60° C. Herein, for example, a cooling rate of more than 5° C. per second may be applied.

(34) After the cooling the aluminum strip 110 in the further cooling zone V, the aluminum strip may be held at the exit temperature of 60° C. for approximately 15 minutes in a further holding zone VI.

(35) Subsequently, further processing steps may be carried out. For example, in a further heating zone VII the temperature may be adjusted between 50° C. and 100° C., and a rolling process of the aluminium strip 110 may be carried out. In a further heat treatment step, for example, paint and/or another alloy may be burned in into the aluminium strip 110.

(36) In the path/temperature diagram in FIG. 5, a temperature curve is shown of an aluminum strip, which may be 1.2 mm thick, and which may pass through a continuous furnace system 100 according to the invention at a speed of 60 m/min.

(37) In the first heating zone I, the first heating unit 101 may be provided, which may heat the aluminium strip 110 up to approx. 550° C. and may maintain this temperature for approx. 10 seconds.

(38) Subsequently, the cooling zone II may begin, wherein in a first step, the temperature of the aluminum strip 110 may be adjusted from 550° C. to 300° C. and in a second step, the temperature may be adjusted from 300° C. to approx. 220° C. at the exit of the cooling zone II. For example, with a strip thickness of from 0.5 mm to 1.2 mm, a cooling rate of more than 50° C. per second may be achieved, and with a material thickness of from 1.3 mm to 4.2 mm, a cooling rate of more than 30° C. per second may be achieved.

(39) The holding zone III and the heating zone IV may hold the aluminium strip 110 almost at a constant temperature and/or increase the temperature of the aluminium strip 110 moderately to approx. 250° C. at the exit of heating zone IV.

(40) Subsequently, in the further cooling zone V, the temperature of the aluminium strip 110 may be cooled from 250° C. down to 60° C. Herein, for example, a cooling rate of more than 5° C. per second may be applied.

(41) After the cooling the aluminum strip 110 in the further cooling zone V, the aluminum strip may be held at the exit temperature of 60° C. for about 15 minutes in a further holding zone VI.

(42) Subsequently, further processing steps may be carried out. For example, in a further heating zone VII, the temperature may be adjusted between 50° C. and 100° C., and a rolling process of the aluminium strip 110 may be carried out. For example, in a further heat treatment step, paint or a further alloy may be burned in into the aluminium strip 110.

(43) Supplementarily, it should be noted that “having” does not exclude other elements or steps, and “an” or “a” does not exclude a plurality. Furthermore, it should be noted that features or steps, which have been described with reference to one of the above embodiment examples, can also be used in combination with other features or steps of other embodiment examples described above. Reference numerals in the claims should not be considered as a limitation.

LIST OF REFERENCE NUMERALS

(44) 100 continuous furnace system

(45) 101 first heating unit

(46) 102 cooling unit

(47) 103 second heating unit

(48) 104 holding unit

(49) 105 further cooling unit

(50) 106 support structure

(51) 107 conveyor track

(52) 108 rollers

(53) 109 conveying direction

(54) 110 metal component

(55) I heating zone

(56) II cooling zone

(57) III holding zone

(58) IV heating zone

(59) V further cooling zone

(60) VI further holding zone

(61) VII further heating zone