WO2013020793A2

WO2013020793A2 - Method and device for cooling continuously running-through material

Info

Publication number: WO2013020793A2
Application number: PCT/EP2012/064252
Authority: WO
Inventors: Cerkez Kaya
Original assignee: Air Liquide Deutschland G.M.B.H; L'air Liquide,Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority date: 2011-08-05
Filing date: 2012-07-20
Publication date: 2013-02-14
Also published as: WO2013020793A3; DE102011109534A1

Abstract

The invention relates to a method for cooling continuously running-through material (1), comprising at least the following steps: a) using a cover (4) to form a gap (2) over at least one part of a surface (3) of the running-through material (1), b) feeding cold-liquefied cooling gas (5) to the gap (2), the volume of the cold-liquefied cooling gas (5) in the gap (2) being increased as a consequence of at least one change in the state of aggregation to gaseous cooling gas (5), c) acceleration of a flow velocity of the gaseous cooling gas (5) as a result of the increase in volume of the cold-liquefied cooling gas (5) in the gap (2) to a multiple of a running-through velocity of the continuously running-through material (1), d) cooling of the at least one part of the surface (3) of the running-through material (1) by the cooling gas (5). This allows heat-treated running-through material (1) to be cooled down to approximately ambient temperature quickly, effectively and over a short length, of for example approximately 80 cm, and directly further processed.

Description

Method and device for cooling continuously running-through material

The present invention relates to a method and a device for cooling continuously running-through material, which are used for cooling heat-treated workpieces.

In the production of metal workpieces, it is often required to subject them to a variety of heat treatments. Particularly in the case of continuously produced workpieces, such as for example material in strand form, metal strips, wires, profiles or tubes and the like, heat treatments are used. These heat treatments may, for example, involve annealing processes, (continuous) casting processes or welding processes. Moreover, the metal workpieces may also become greatly heated during forming processes, such as for example deep drawing. Therefore, subsequent cooling of the workpieces is often required, in particular to avoid deformations of the workpieces or increased tool wear.

Methods and devices for cooling heat-treated workpieces are already known from the prior art. In the case of these methods and devices, workpieces are often cooled with water or a water/oil emulsion. These methods and devices have the disadvantage that the cooling with water or a water/oil emulsion may cause the formation of oxide films and scale on the surface of the cooled workpieces, so that they subsequently have to be cleaned. Moreover, the water used for the cooling or the water/oil emulsion that is used has to be laboriously filtered or expensively disposed of, which may entail considerable costs.

In addition, methods and devices for cooling heat-treated workpieces with cold-liquefied gas are also known. In the case of these methods and devices, the heat-treated workpieces are sprayed with the cold-liquefied gas in order to cool them to a desired temperature. To achieve highest possible productivity, it is aimed to obtain a production rate that is as high as possible. For example, in the case of longitudinally welded tubes, this may be over 10 metres per minute. At such high production rates, however, it has been found that the cooling of these continuously produced workpieces with liquefied gases such as nitrogen, argon, carbon dioxide or carbon dioxide snow by conventional devices and methods, in which the liquefied gases are sprayed onto the workpieces, is not sufficient to cool the workpieces to a desired temperature within a desired time. This is attributable in particular to the fact that, when they impinge on the heat-treated workpieces, drops of the liquefied gas partially vaporize and are subsequently no longer in sufficient contact with the workpieces to be cooled.

The object of the invention is therefore to solve at least partially the problems described with respect to the prior art and, in particular, to provide a method for cooling continuously running-through material that is distinguished by a particularly high cooling performance and does not require any cleaning before downstream further processing. Furthermore, it is also intended to provide a cooling device for cooling continuously running-through material that is likewise distinguished by a particularly effective cooling performance.

These objects are achieved by a method according to the features of Patent Claim 1 and a device according to the features of Patent Claim 10. Further advantageous refinements of the invention are specified in the dependently formulated patent claims. It should be pointed out that the features individually recited in the dependently formulated patent claims may be combined with one another in any desired technologically meaningful way and define further refinements of the invention. In addition, the features specified in the patent claims are specified in more precise detail and explained in the description, presenting further preferred refinements the invention.

The method according to the invention for cooling continuously running-through material comprises at least the following steps: a) using a cover to form a gap over at least one part of a surface of the running-through material, b) feeding cold-liquefied cooling gas to the gap, the volume of the cold-liquefied cooling gas in the gap being increased as a consequence of at least one change in the state of aggregation to gaseous cooling gas, c) acceleration of a flow velocity of the gaseous cooling gas as a result of the increase in volume of the cold- liquefied cooling gas in the gap to a multiple of a running-through velocity of the continuously running- through material, d) cooling of the at least one part of the surface of the running-through material (1) by the cooling gas. The continuously running-through material is, in particular, material in strand form, metal strips, wires, profiles or tubes and the like, which substantially consist of metal and have been subjected to a heat treatment in an upstream process. This heat treatment may, for example, involve annealing processes, (continuous) casting processes, welding processes and/or a forming process, such as for example deep drawing. During the cooling, the continuously running-through material is continuously in motion. The motion of the continuously running-through material may take place, for example, as a result of conveyor belts, conveying rollers and/or other known conveying means, preferably no conveying means being arranged in the gap. In the case of the proposed method, firstly a cover is used to form a gap over at least one part of a surface of the continuously running-through material or over the entire surface of the continuously running-through material. The cover may be, for example, a metal sheet, a profile (for example a U profile or L profile) or a tube. The cover consists in particular of metal, plastic and/or ceramic. The cover may, in particular, be of a multilayered structure and comprise at least one (heat) insulator, which at least partially (heat) insulates the gap from a surrounding ambience. In particular if the cover is produced from plastic, the thermal conductivity of the cover is less than 0.5 W/K*m. The cover is preferably electrically nonconducting. Moreover, in particular, the cover is fixedly arranged, the continuously running-through material either being moved past the cover or in the case of a tubular cover moved through the cover. The gap is, for example, a channel and/or a space which is bounded by the cover and at least one part of the surface of the running-through material.

It is then proposed to provide in this gap a cold-liquefied cooling gas, for example nitrogen, argon and/or carbon dioxide or carbon dioxide snow, preferably carbon dioxide. In the gap, the cold-liquefied cooling gas is heated by the continuously running-through material, so that the cold- liquefied cooling gas changes its state of aggregation from liquid to gaseous. This has the consequence that the volume of the cold-liquefied cooling gas in the gap increases considerably. As a result, the pressure inside the gap increases, for example to 2 bar or more, so that the gaseous cooling gas flows through the gap at high velocity, for example at least 20 km/h, preferably at least 100 km/h and particularly preferably at least 200 km/h. The running- through velocity of the continuously running-through material, with which the continuously running-through material is made to pass the gap, is up to 10 m/min, preferably even up to 15 m/min, particularly preferably even 20 m/min or more. In any case, the gaseous cooling gas is accelerated in the gap to a velocity which is a multiple of the running-through velocity of the continuously running-through material, the running-through velocity being the velocity of the continuously running-through material at the gap or through the gap. The high velocity of the gaseous cooling gas in the gap advantageously leads to particularly intense cooling of the continuously running-through material. Furthermore, it is advantageous if a cross section of a first end of the gap is reduced by a slotted piece. The first end of the gap may be, for example, one of two openings of a channel that link the channel to the surrounding ambience. For this purpose, the slotted piece is adapted in particular to an outer contour of the continuously running-through material, so that the open cross section of the first end of the gap is preferably minimized. However, it should be taken into consideration that the slotted piece should not lie against the continuously running-through material, in order that the continuously running-through material can be made to pass freely by or through the gap. As a result, cooling gas can be substantially prevented from emerging from the first end of the gap into the surrounding ambience, so that substantially all the cooling gas flows along the gap in the direction of a second end of the gap.

It is particularly advantageous if the continuously running-through material is cooled down in the region of the gap from at least 500°C to at most 20°C within a maximum of 5 seconds. It is particularly preferred in this respect if the continuously running-through material is cooled down in the region of the gap even from at least 700°C within a maximum of 3 seconds, or most preferably from at least 900°C within a maximum of 3 seconds. This particularly high cooling rate has a particularly advantageous effect on the continuously running-through material and/or downstream process steps. Furthermore, it is advantageous if the gap has a length of a maximum of 80 centimetres. The length of the gap is measured in particular along the conveying direction of the continuously running-through material along the gap. As a result, cooling is ensured in a particularly compact region .

Furthermore, it is advantageous if a height of the gap corresponds as a maximum to a material thickness of the continuously running-through material. The height is preferably a maximum of 50%, particularly preferably a maximum of 10% of the material thickness. The height is the perpendicular distance between the surface of the running- through material and the cover. The material thickness may be both a wall thickness of the continuously running- through material (for example in the case of a hollow profile or a tube) and - particularly in the case of a solid material - a diameter of the continuously running- through material. This achieves the effect that the cooling gas is conducted in the gap in the direct vicinity of the continuously running-through material, and consequently an intense heat exchange between the continuously running- through material and the cooling gas is ensured.

It is likewise advantageous if a height of the gap is a maximum of 10 centimetres. The height of the gap is preferably a maximum of 5 centimetres, particularly preferably a maximum of 1 centimetre.

In a further embodiment, it is provided that the cold- liquefied cooling gas is provided in the gap by at least one nozzle. This allows particularly exact metering and distribution of the cold-liquefied cooling gas in the gap to be achieved. The cooling gas, preferably carbon dioxide, is provided here in the gap by the nozzle in particular at a pressure of 10 to 60 bar. Furthermore, it is advantageous if the cold-liquefied cooling gas is sprayed in the direction of the continuously running-through material by a plurality of nozzles, in particular from various angles. For this purpose, the plurality of nozzles may, for example, be distributed over a circumference of the continuously running-through material, for example in a star-shaped manner, so that particularly uniform cooling can be achieved. Depending on the cooling requirements and the running-through velocity of the running-through material, it is also possible to activate a number of nozzles arranged one behind the other.

It is likewise advantageous if the gap has directing surfaces to form a turbulent flow of the cooling gas. These directing surfaces serve for thoroughly mixing the cooling gas in the gap, so that particularly effective cooling is achieved by avoiding a laminar flow in the gap.

According to a further aspect of the invention, a cooling device for cooling continuously running-through material is also proposed, in particular for carrying out the method according to one of Patent Claims 1 to 9, which device comprises at least one nozzle for feeding cold-liquefied cooling gas into a gap, a cover being used to form the gap at least over one part of a surface of the running-through material, so that cooling of the at least one part of the surface of the running-through material can be achieved as a consequence of cooling gas flowing through the gap. With respect to the cooling device according to the invention, reference is made in a corresponding way to the description of the method according to the invention.

The invention and the associated technical field are explained in more detail below on the basis of the figures. It should be pointed out that the figures show particularly preferred variants of embodiments of the invention, which however is not restricted to these. In the schematic figures :

Figure 1 shows an exemplary embodiment of a cooling device according to the invention,

Figure 2 shows a longitudinal section through the exemplary embodiment of the cooling device according to the invention as shown in Figure 1,

Figure 3 shows a cross section through the exemplary embodiment of the cooling device according to the invention as shown in Figure 1, Figure 4 shows a further exemplary embodiment of a cooling device according to the invention, and

Figure 5 shows a cross section through the exemplary embodiment of the cooling device according to the invention as shown in Figure 4.

Figure 1 shows a cooling device 14 with a cover 4, which covers a weld seam 15 on a surface 3 of a continuously running-through material 1, so that a gap 2 is formed between the cover 4 and the surface 3 of the continuously running-through material 1. The cooling device 14 is fixedly arranged, with a stand that is not shown here. The gap 2 has a length 9, a height 10 and a first end 7 and a second end 16. The continuously running-through material 1 is made to pass the gap 2 in the running-through direction 17.

Figure 2 shows a longitudinal section along a longitudinal extent of the cooling device 14 as shown in Figure 1. Figure 2 shows the cooling device 14 with the cover 4, which with the surface 3 of the material 1 bounds a gap 2. Arranged within the gap 2 are a plurality of nozzles 12, which spray cooling gas 5 in the direction of the surface 3 of the material 1. For this purpose, the nozzles 12 are connected via supply lines 19 to a cooling gas source 18. The supply lines 19 have valves 24, which are connected in a data-conducting manner to a controller not shown here. The controller is designed for feeding the cooling gas 5 to the gap 2 according to requirements via the respective nozzles 12. The gap 2 has at its first end 7 a slotted piece 8, so that the first end 7 of the gap 2 is closed off in a substantially gastight manner with respect to a surrounding ambience 23. The cooling gas 5 fed into the gap 2 through the nozzles 12 expands in the gap 2 and, as a result, flows along the gap 2 in the direction of a second end 16 of the gap 2 and escapes there into the surrounding ambience 23. Moreover, the material 1 has a material thickness 11. Also formed in the gap 2 is at least one directing surface 13, which thoroughly mixes the cooling gas 5 in the gap 2. Also arranged in the surrounding ambience 23 is a suction extractor 21, which is schematically indicated here and at least partially sucks away the cooling gas 5 flowing out of the gap 2 into the surrounding ambience 23 through the second end 16. It should be made clear that the suction extractor 21 may also be arranged within the gap 2, in particular in the region of the second end 16.

Figure 3 shows a cross section through the slotted piece 7 along the plane 20 indicated in Figure 2. Figure 3 shows the material 1 with the weld seam 15, which protrudes beyond the surface 3 of the material 1. Also shown is the cover 4, which together with the surface 3 of the material 1 bounds the gap 2. The first end 7 of the gap 2 has a cross section 6, which is substantially closed by the slotted piece 8 represented here as hatched. Figure 4 shows a further exemplary embodiment of the cooling device 14, in this exemplary embodiment the continuously running-through material 1 being completely surrounded by a tubular cover 4. The cover 4 encloses a gap 2, which in this exemplary embodiment is of an annular form. The continuously running-through material 1 is moved through the gap 2 in the running-through direction 17. The gap 2 has a height 10, which extends perpendicularly from the surface 3 of the continuously running-through material to the cover 4. Using a plurality of nozzles 12, cold- liquefied cooling gas 5 is fed into the gap 2. For this purpose, the nozzles 12 are connected to a cooling gas source 18 by way of supply lines 19. A first end 7 of the gap 2 is closed off in a substantially gastight manner from a surrounding ambience 23 by a slotted piece 8. The heating of the cooling gas 5 in the gap 2 causes the cold-liquefied cooling gas 5 to expand in the gap 2 to form gaseous cooling gas 5, whereby the volume of the cooling gas 5 is multiplied. As a result, the cooling gas 5 flows along the gap 2 in the direction of a second end 16 of the gap 2. In order to achieve particularly effective cooling of the material 1, the cover 4 is of a multilayered structure and has in particular an insulator 22. Also arranged in the surrounding ambience 23 is a suction extractor 21, which is schematically represented here and at least partially sucks away the cooling gas 5 flowing out through the second end 16 of the gap 2. Figure 5 shows a cross section through the plane 20 indicated in Figure 4. Represented in Figure 5 is the cover 4, which encloses the continuously running-through material 1 and thereby forms the gap 2. Also shown here in a hatched form is the slotted piece 8, which substantially seals off the cross section 6 of the gap 2 in the region of the first end, but at the same time does not touch the continuously running-through material 1.

The method according to the invention and the cooling device according to the invention are distinguished by particularly effective cooling of the continuously running- through material. The method according to the invention and the cooling device according to the invention are particularly advantageous when used for cooling welded workpieces, preferably longitudinally welded profiles or tubes and the like, in particular using arc or laser welding processes.

List of designations

Material

Gap

Surface

Cover

Cooling gas

Cross section

First end

Slotted piece

Length

Height

Material thickness

Nozzle

Directing surface

Cooling device

Weld seam

Second end

Running-through direction

Cooling gas source

Supply lines

Plane

Suction extractor

Insulator

Surrounding ambience

Valve

Claims

Method for cooling continuously running-through material (1), comprising at least the following steps: a) using a cover (4) to form a gap (2) over at least one part of a surface (3) of the running-through material ( 1 ) , b) feeding cold-liquefied cooling gas (5) to the gap (2), the volume of the cold-liquefied cooling gas (5) in the gap (2) being increased as a consequence of at least one change in the state of aggregation to gaseous cooling gas (5) , c) acceleration of a flow velocity of the gaseous cooling gas (5) as a result of the increase in volume of the cold-liquefied cooling gas (5) in the gap (2) to a multiple of a running-through velocity of the continuously running-through material (1), d) cooling of the at least one part of the surface (3) of the running-through material (1) by the cooling gas (5) .

Method according to Patent Claim 1, a cross section (6) of a first end (7) of the gap (2) being reduced by a slotted piece (8) .

Method according to either of the preceding patent claims, the continuously running-through material (1) being cooled down in the region of the gap (2) from at least 500°C to at most 20°C, preferably below 15°C, within a maximum of 5 seconds.

Method according to one of the preceding patent claims, a length (9) of the gap (2) being a maximum of 100 cm, preferably approximately 80 cm.

5. Method according to one of the preceding patent claims, a height (10) of the gap (2) corresponding as a maximum to a material thickness (11) of the continuously running-through material (1).

5. Method according to one of the preceding patent claims, a height (10) of the gap being a maximum of 10 centimetres .

7. Method according to one of the preceding patent claims, the cold-liquefied cooling gas being provided in the gap (2) by at least one nozzle (12) . 8. Method according to one of the preceding patent claims, the cold-liquefied cooling gas (4) being sprayed in the direction of the continuously running-through material

(1) by a plurality of nozzles (12), in particular from various angles.

Method according to one of the preceding patent claims, the gap (2) having directing surfaces (13) to form a turbulent flow of the cooling gas (5) . 10. Cooling device (14) for cooling continuously running- through material (1), in particular for carrying out the method according to one of Patent Claims 1 to 9, comprising at least one nozzle (11) for feeding cold- liquefied cooling gas (4) into a gap (2), a cover being used to form the gap (2) at least over one part of a surface (3) of the running-through material (1), so that cooling of the at least one part of the surface of the running-through material can be achieved as a consequence of cooling gas flowing through the gap.