DE102011109534A1 - Method and device for cooling continuously passing material - Google Patents

Abstract

The present invention relates to a method for cooling continuously passing material (1), comprising at least the following steps: a) formation of a gap (2) over at least part of a surface (3) of the continuous material (1) by means of a cover ( 4), b) supplying cold-liquefied cooling gas (5) to the gap (2), wherein the volume of the cold-liquefied cooling gas (5) in the gap (2) increases to gaseous cooling gas (5) as a result of at least one change of state of matter, c) Accelerating a flow velocity of the gaseous refrigerant gas (5) by increasing the volume of the refrigerant-liquefied refrigerant gas (5) in the gap (2) to a multiple of a flow rate of the continuous material (1), d) cooling the at least part of the surface (3 ) of the passing material (1) with the cooling gas (5). Thus, heat-treated continuous material (1) can be cooled quickly, effectively and over a short length of, for example, about 80 cm to about ambient temperature and processed directly.

Description

The present invention relates to a method and apparatus for cooling continuously passing material used to cool heat treated workpieces.

In the production of metallic workpieces, it is often necessary to subject them to a variety of heat treatments. In particular, in continuously produced workpieces, such as extruded material, metal strips, wires, profiles or pipes and the like, heat treatments are applied. These heat treatments can be, for example, annealing processes, (strand) casting processes or welding processes. In addition, the metallic workpieces can also heat during forming processes, such as deep-drawing, strong. Often, therefore, a subsequent cooling of the workpieces is required to avoid in particular deformations of the workpieces or increased tool wear.

Methods and devices for cooling heat-treated workpieces are already known from the prior art. In these workpieces are often cooled with water or a water / oil emulsion. These methods and devices have the disadvantage that by cooling with water or a water / oil emulsion can form oxide layers and scale on the surface of the cooled workpieces, so that they must be subsequently cleaned. In addition, the water used for cooling or the water / oil emulsion used must be consuming filtered or disposed of expensive, which can result in significant costs.

In addition, methods and apparatus for cooling heat treated workpieces with cold liquefied gas are also known. In these methods and apparatus, the heat-treated workpieces are sprayed with the cold-liquefied cooling gas to cool it to a desired temperature. To achieve the highest possible productivity, the highest possible production speed is sought. For example, this may be over 10 meters per minute for longitudinally welded pipes. However, at such high production speeds, it has been found that cooling these continuously produced workpieces with liquefied gases such as nitrogen, argon, carbon dioxide or carbon dioxide snow with conventional apparatus and methods where the liquefied gases are sprayed onto the workpieces is not sufficient to hold the workpieces in place to cool to a desired temperature for a desired time. This is due in particular to the fact that drops of the liquid gas partially evaporate when hitting the heat-treated workpieces and subsequently are no longer in sufficient contact with the workpieces to be cooled.

The object of the invention is therefore to solve the problems described with reference to the prior art at least partially and in particular to provide a method for cooling continuously passing material, which is characterized by a particularly high cooling performance and requires no cleaning before downstream processing. Furthermore, a cooling device for cooling continuously running material should be specified, which is also characterized by a particularly effective cooling performance.

These objects are achieved with a method according to the features of patent claim 1 and a device according to the features of patent claim 10. Further advantageous embodiments of the invention are specified in the dependent formulated claims. It should be noted that the features listed individually in the dependent formulated claims can be combined with each other in any technologically meaningful manner and define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

• a) Bildung eines Spalts über zumindest einem Teil einer Oberfläche des durchlaufenden Materials mit Hilfe einer Abdeckung,
• b) Zuführung von kälteverflüssigtem Kühlgas zu dem Spalt, wobei sich das Volumen des kälteverflüssigtem Kühlgases in dem Spalt infolge zumindest einer Aggregatzustandsänderung zu gasförmigen Kühlgas erhöht,
• c) Beschleunigung einer Strömungsgeschwindigkeit des gasförmigen Kühlgases durch die Erhöhung des Volumens des kälteverflüssigtem Kühlgases in dem Spalt auf ein Mehrfaches einer Durchlaufgeschwindigkeit des kontinuierlich durchlaufenden Materials,
• d) Kühlen des zumindest einen Teils der Oberfläche des durchlaufenden Materials (1) mit dem Kühlgas.

The method according to the invention for cooling continuously passing material has at least the following steps:

• a) forming a gap over at least a part of a surface of the continuous material by means of a cover,
• b) supplying cold-liquefied cooling gas to the gap, wherein the volume of the cold-liquefied cooling gas in the gap increases as a result of at least one state of aggregate change to gaseous cooling gas,
• c) accelerating a flow velocity of the gaseous refrigerant gas by increasing the volume of the refrigerant-liquefied refrigerant gas in the gap to a multiple of a flow rate of the continuously-passing material,
• d) cooling the at least part of the surface of the continuous material ( 1 ) with the cooling gas.

The continuously running material is in particular extrudates, metal strips, wires, profiles or tubes and the like, which consist essentially of metal, and in an upstream process of a Heat treatment were subjected. This heat treatment can be, for example, annealing processes, (strand) casting processes, welding processes and / or a forming process, such as deep-drawing. The continuously running material is in continuous motion during cooling. The movement of the continuously passing material can be effected, for example, by conveyor belts, conveyor rollers and / or by other known conveying means, wherein preferably no conveying means are arranged in the gap. In the proposed method, a gap is first formed over at least a portion of a surface of the continuously passing material or over the entire surface of the continuously passing material by means of a cover. The cover can be, for example, a metal sheet, a profile (eg U-profile or L-profile) or a pipe. The cover consists in particular of metal, plastic and / or ceramic. The cover may in particular be of multilayer construction and comprise at least one (heat) insulator which at least partially (thermally) isolates the gap from an environment. The thermal conductivity of the cover, especially if the cover is made of plastic, is less than 0.5 W / K · m. Preferably, the cover is electrically non-conductive. In particular, the cover is arranged in a stationary manner, wherein the continuously running material either moves past the cover or is moved through the cover in the case of a tubular cover. The gap is, for example, a channel and / or a space which is bounded by the cover and at least part of the surface of the continuous material.

It is now proposed in this gap a cold liquefied cooling gas, for. As nitrogen, argon and / or carbon dioxide or carbon dioxide snow provide. In the gap, the cold-liquefied refrigerant gas is heated by the continuously passing material, so that the refrigerant-liquefied refrigerant gas changes its state of aggregation from liquid to gas. This has the consequence that the volume of the cold-liquefied cooling gas in the gap increases considerably. As a result, the pressure in the interior of the gap increases, for example, to 2 bar or more, so that the gaseous cooling gas flows through the gap at high speed, for example at least 20 km / h, preferably at least 100 km / h and particularly preferably at least 200 km / h , The flow rate of the continuous material passing the continuous material past the nip is up to 10 m / min, preferably even up to 15 m / min, more preferably even 20 m / min or more. In any event, the gaseous cooling gas in the nip is accelerated to a velocity which is several times the flow rate of the continuously passing material, where the flow rate is the velocity of the continuous material at the nip or through the nip. The high velocity of the gaseous cooling gas in the gap leads advantageously to a particularly strong cooling of the continuously passing material.

Furthermore, it is advantageous if a cross section of a first end of the gap is reduced with a backdrop. The first end of the gap may, for example, be one of two openings of a channel connecting the channel to the environment. For this purpose, the link is particularly adapted to an outer contour of the continuously passing material, so that the open cross section of the first end of the gap is preferably minimized. It should be noted, however, that the gate should not rest against the continuously passing material so that the continuously passing material can pass or pass freely through the nip. As a result, it can be substantially prevented that cooling gas escapes from the first end of the gap into the environment, so that essentially all of 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 material in the region of the gap is cooled within 5 seconds from at least 500 ° C to at most 20 ° C. In this case, it is particularly preferred if the continuously running material in the region of the gap is cooled within at least 900 ° C. within a maximum of 3 seconds, even of at least 700 ° C. or more preferably within a maximum of 3 seconds. This particularly high cooling rate has a particularly advantageous effect on the continuously passing material and / or subsequent process steps.

Furthermore, it is advantageous if the gap has a maximum length of 80 centimeters. The length of the gap is measured in particular along the conveying direction of the continuously running material along the gap. This ensures cooling in a particularly compact area.

Furthermore, it is advantageous if a height. the gap corresponds at most to a material thickness of the continuously passing material. It is preferred that the height is at most 50%, more preferably at most 10% of the material thickness. The height is the vertical distance between the surface of the material passing through and the cover. The material thickness may be both a wall thickness of the continuous material passing through (eg in the case of a hollow profile or a tube) and also, in particular in the case of a Solid material - to be a diameter of the continuous material. This ensures that the cooling gas is conducted in the immediate vicinity of the continuously passing material in the gap and thus an intense heat exchange between continuously passing material and cooling gas is ensured.

It is also advantageous if a height of the gap is at most 10 centimeters. It is preferred that the height of the gap is at most 5 centimeters, more preferably at most 1 centimeter.

In a further embodiment it is provided that the cold-liquefied cooling gas is provided with at least one nozzle in the gap. In this way, a particularly accurate metering and distribution of the cold-liquefied cooling gas in the gap can be achieved. The cooling gas, preferably carbon dioxide, is in this case provided in particular with a pressure of 10 to 60 bar with the nozzle in the gap.

Furthermore, it is advantageous if the cold-liquefied cooling gas is sprayed with a plurality of nozzles, in particular from different angles, in the direction of the continuously passing material. For this purpose, the plurality of nozzles, for example. Over a circumference of the continuously passing material, for. B. star-shaped, be distributed, so that a particularly uniform cooling can be achieved. Also combing several nozzles arranged one behind the other depending on the cooling demand and throughput speed of the material passing through be switched on.

It is also advantageous if the gap has guide surfaces for forming a turbulent flow of the cooling gas. These guide surfaces serve to mix the cooling gas in the gap, so that a 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 passing material, in particular for carrying out the method according to one of the claims 1 to 9, is proposed, which has at least one nozzle for supplying cold-liquefied cooling gas into a gap, said gap at least is formed between a part of a surface of the continuous material by means of a cover, so that a cooling of the at least part of the surface of the continuous material is achieved as a result of a flow through the gap with cooling gas.

With regard to the cooling device according to the invention, reference is made in a corresponding manner to the description of the method according to the invention.

The invention and the technical environment will be explained in more detail with reference to FIGS. It should be noted that the figures show particularly preferred embodiments of the invention, but this is not limited thereto. They show schematically:

1 : an embodiment of a cooling device according to the invention,

2 a longitudinal section through the embodiment of the cooling device according to the invention according to 1 .

3 FIG. 2: a cross section through the exemplary embodiment of the cooling device according to the invention according to FIG 1 .

4 a further embodiment of a cooling device according to the invention, and

5 FIG. 2: a cross section through the exemplary embodiment of the cooling device according to the invention according to FIG 4 ,

1 shows a cooling device 14 with a cover 4 that a weld 15 on a surface 3 a continuous material 1 covered so that between the cover 4 and the surface 3 of continuously passing material 1 A gap 2 is formed. The cooling device 14 is stationary with a tripod not shown here. The gap 2 has a length 9 , a high 10 as well as a first end 7 and a second end 16 on. The continuous material 1 gets at the gap 2 in the direction of passage 17 past.

The 2 shows a longitudinal section along a longitudinal extent of the cooling device 14 according to 1 , The 2 shows the cooling device 14 with the cover 4 that with the surface 3 of the material 1 a gap 2 limited. Inside the gap 2 are a plurality of nozzles 12 arranged the cooling gas 5 towards the surface 3 of the material 1 spray. These are the nozzles 12 via supply lines 19 with a cooling gas source 18 connected. The supply lines 19 have valves 24 on, which are connected to a data controller not shown here. The controller is adapted to the refrigerant gas 5 as required via the respective nozzles 12 the gap 2 supply. The gap 2 indicates at its first end 7 a backdrop 8th on, so the first end 7 of the gap 2 towards an environment 23 is sealed substantially gas-tight. That through the nozzles 12 in the gap 2 supplied cooling gas 5 expands in the gap 2 and thereby flows along the gap 2 towards a second end 16 of the gap 2 and escapes into the environment 23 , The material 1 also has a material thickness 11 on. In addition, in the gap 2 at least one guide surface 13 formed, which is the cooling gas 5 in the gap 2 mixed. It is also in the area 23 a here schematically indicated suction 21 arranged that out of the gap 2 in the nearby areas 23 through the second end 16 outflowing cooling gas 5 at least partially sucks. It should be clarified that the suction 21 also within the gap 2 , especially in the region of the second end 16 can be arranged.

3 shows a cross section through the backdrop 7 along the in 2 indicated area 20 , The 3 shows the material 1 with the weld 15 that over the surface 3 of the material 1 protrudes. In addition, the cover 4 shown along with the surface 3 of the material 1 the gap 2 limited. The first end 7 of the gap 2 has a cross section 6 on, by the hatched here backdrop 8th is essentially closed.

The 4 shows a further embodiment of the cooling device 14 , In this embodiment, the continuously passing material 1 completely from a tubular cover 4 is surrounded. The cover 4 encloses a gap 2 which is annular in this embodiment. Through the gap 2 is in the direction of passage 17 the continuous material 1 emotional. The gap 2 has a height 10 on, perpendicular to the surface 3 of continuously passing material up to the cover 4 extends. In the gap 2 is using a plurality of nozzles 12 Refrigerated liquefied cooling gas 5 the gap 2 fed. These are the nozzles 12 via supply lines 19 with a cooling gas source 18 connected. A first end 7 of the gap 2 is opposite to an environment 23 with a backdrop 8th essentially gas-tight. By heating the cooling gas 5 in the gap 2 the refrigerated liquefied refrigerant gas expands 5 in the gap 2 to gaseous cooling gas 5 , which reduces the volume of the cooling gas 5 multiplied. As a result, the cooling gas flows 5 along the gap 2 towards a second end 16 of the gap 2 , For a particularly effective cooling of the material 1 to achieve is the cover 4 multi-layered and in particular has an insulator 22 on. It is also in the area 23 a suction shown here schematically 21 arranged that through the second end 16 of the gap 2 outflowing cooling gas 5 at least partially sucks.

5 shows a cross section through the in 4 indicated area 20 , In the 5 is the cover 4 shown, which is the continuous material passing through 1 encloses and thereby the gap 2 forms. In addition, the scenery is hatched here 8th shown the cross section 6 of the gap 2 Essentially seals in the region of the first end, while the continuously passing material 1 but not touched.

The inventive method and the cooling device according to the invention are characterized by a particularly effective cooling of the continuously passing material.

LIST OF REFERENCE NUMBERS

1

material

2

gap

3

surface

4

cover

5

cooling gas

6

cross-section

7

First end

8th

scenery

9

length

10

height

11

material thickness

12

jet

13

Leifläche

14

cooler

15

Weld

16

Second end

17

Throughput direction

18

Cooling gas source

19

leads

20

area

21

suction

22

insulator

23

Surroundings

24

Valve

Claims (10)

Method for cooling continuously passing material ( 1 ), comprising at least the following steps: a) formation of a gap ( 2 ) over at least part of a surface ( 3 ) of the passing material ( 1 ) with the help of a cover ( 4 ), b) supplying refrigerated liquefied cooling gas ( 5 ) to the gap ( 2 ), wherein the volume of the cold-liquefied cooling gas ( 5 ) in the gap ( 2 ) as a result of at least one change of state of matter to gaseous cooling gas ( 5 c) acceleration of a flow velocity of the gaseous cooling gas ( 5 ) by increasing the volume of the cold-liquefied cooling gas ( 5 ) in the gap ( 2 ) at a multiple of a throughput speed of the continuously passing material ( 1 ) d) cooling the at least part of the surface ( 3 ) of the passing material ( 1 ) with the cooling gas ( 5 ). Method according to claim 1, wherein a cross-section ( 6 ) of a first end ( 7 ) of the gap ( 2 ) with a backdrop ( 8th ) is reduced. Method according to one of the preceding claims, wherein the continuously passing material ( 1 ) in the region of the gap ( 2 ) within a maximum of 5 seconds from at least 500 ° C to at most 20 ° C, preferably below 15 ° C, is cooled. Method according to one of the preceding claims, wherein a length ( 9 ) of the gap ( 2 ) is at most 100 cm, preferably about 80 cm. Method according to one of the preceding claims, wherein a height ( 10 ) of the gap ( 2 ) maximum one material thickness ( 11 ) of the continuously passing material ( 1 ) corresponds. Method according to one of the preceding claims, wherein a height ( 10 ) of the gap is at most 10 centimeters. Method according to one of the preceding claims, wherein the cold-liquefied refrigerant gas with at least one nozzle ( 12 ) in the gap ( 2 ) provided. Method according to one of the preceding claims, wherein the cold-liquefied cooling gas ( 4 ) with a plurality of nozzles ( 12 ), in particular from different angles, in the direction of the continuously passing material ( 1 ) is sprayed. Method according to one of the preceding claims, wherein the gap ( 2 ) Baffles ( 13 ) for forming a turbulent flow of the cooling gas ( 5 ) having. Cooling device ( 14 ) for cooling continuously passing material ( 1 ), in particular for carrying out the method according to one of the claims 1 to 9, comprising at least one nozzle ( 11 ) for supplying cold-liquefied cooling gas ( 4 ) into a gap ( 2 ), where the gap ( 2 ) at least between a part of a surface ( 3 ) of the passing material ( 1 ) is formed with the aid of a cover, so that a cooling of the at least part of the surface of the continuous material as a result of a flow through the gap with cooling gas can be achieved.

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