ES2332811T3 - PROCEDURE AND DEVICE FOR QUICK COOLING WORK PIECES. - Google Patents

Abstract

Procedure for cooling a workpiece (1), in which the workpiece (1) is introduced into a cooling zone (10) that borders a cold box (3), and in which a cooling medium is fed to the cold box (3), the cooling medium comprising a liquefied gas or a mixture of liquefied gases, whose heat of evaporation is used to cool the cold box (3) and to cool the surface of the workpiece (1), characterized in that the cooling medium leaves the cold box (3) by one or several nozzles (5) and is led to the cooling zone (10) through said nozzle or nozzles (5).

Description

Procedure and device for cooling Quickly work pieces.

The invention concerns a method for cooling a workpiece, into which the workpiece is introduced I work in a refrigeration zone that borders a cold box, and in which a cooling medium is fed to the cold box, the cooling medium comprising a liquefied gas or a mixture of liquefied gases whose evaporation heat is used to cool the cold box and to cool the surface of the piece of job.

Also, the invention relates to a device for cooling a workpiece comprising a box  cold with a feed for a cooling medium and an area of refrigeration to receive the work piece, limiting the box cold and the cooling zone with each other and being set feeding in a suitable way to introduce liquefied gas or a mixture of liquefied gases.

A large number of procedures are known and cooling devices For example in the field of heat treatment have been used for centuries a large number of procedures and devices to cool and cool sharply work pieces. They are common, for example, cooling abrupt in liquids such as oils, water, emulsions or others, as well as abrupt cooling in salts or with the help of gases. The gases are conventionally used in multiple ways, such as, for example, under high pressure, which increases the gas capacity to transport heat energy. With the same objective is carried out according to the state of the art to be put into gas contact, under high relative speed, with the surface hot from a workpiece that must be cooled. According to a relatively recent procedure, the so-called "cooling fast with gas ", high pressure and high pressure gas is contacted output speed with the hot surface of the piece of Work to be cooled.

Document GB 1 287 325 A reveals a device for sequentially cooling work pieces that are transported through a thermally insulated chamber and that cooled by evaporation of liquid nitrogen that is fed to the camera.

US 5,083,436 discloses a device to cool and contract work pieces that are transported to a treatment station in a production line that presents a refrigeration chamber, a transport equipment, at least one pipe that runs substantially vertical to transport a cryogenic liquid from a bath to an outlet placed above of the bath, vats for storing the cryogen bath, sheets deviation to decelerate the opposite current of cryogenic gas and a gate that holds the gas in the chamber of refrigeration.

As a state of the art not yet published a cooling procedure for tubes and others is known semi-finished products (for example, rods, profiles, wire and similar), in which the work pieces to be cooled are cooled in the form of packages or individually by means of a field of nozzles adapted in its shape, through which it blows gas over the work pieces, while these pieces of Work move through the nozzle field. The field of nozzles can be here confined also with adaptation of way inside your accommodation. However, the result of cooling could be even better, especially for parts of work with a starting temperature of more than 550ºC.

The purpose of the invention consists in provide an improved procedure and a device for implementation of this part cooling procedure of work.

The problem posed is solved by the side of the procedure due to the fact that the work piece is introduced into a cooling zone that borders a cold box, and because a cooling medium is fed to the cold box, the cooling medium comprising a liquefied gas or a mixture of liquefied gases whose evaporation heat is used to cool the cold box and to cool the surface of the workpiece,  and the cooling medium coming out of the cold box through one or several nozzles and said means being driven to the area of cooling through said nozzle or nozzles.

According to the invention, the gas is used introduced into the cooling zone through the nozzles -in liquid or gaseous state- to cool the workpiece by convection On the other hand, the cooling medium cools also the cold box that borders the cooling zone. From this way, the heat transfer by radiation is reinforced Dominant especially at high temperatures.

As a cooling medium it is used preferably a liquefied gas or a mixture of gases in form liquid and gas, whose heat of evaporation is used to refrigerate the cold box and / or to cool the surface of the Workpiece. The environment of the workpiece is carried with this at a temperature that makes cooling possible Especially effective work piece. Especially for the If the workpiece has a high temperature of heading of more than 550ºC, you can take into account the procedure according to the invention the predominance of the transfer of heat by heat radiation that occurs in this range of temperature compared to the transfer of heat by transport of heat or by convection.

The use of liquefied gas or a mixture of gases in liquid and gaseous form present, in addition to the temperature particularly advantageously low that is achieved with it, the advantages of a clean environmentally friendly process in which can be dispensed with further cleaning of the workpiece work, there is no corrosion caused by the process and can well control the development of the process based on the Good dosing capacity of the cooling medium. On the whole, an extremely effective cooling procedure is available on a device with only a small spatial extent.

Preferably, it evaporates in its entirety or in split the liquefied gas or the mixture of liquefied gases in the cold box, using the heat of evaporation in whole or in part to Refrigerate the cold box.

Alternatively or additionally, the gas liquid or a mixture of gases in liquid and gaseous form enters advantageously in action, in whole or in part, by direct evaporation on the surface of the workpiece, using the heat of evaporation in whole or in part to Cool the surface of the workpiece.

According to an improvement especially advantageous of the invention, the workpiece moves through the cooling zone, the cooling zone being adapted to the shape of the workpiece, so that, on the one hand, the cooling medium remains in the cooling zone for a long enough time for the surface of the piece of work can give enough heat to the environment coolant and on the other hand the coolant then heated leaves the cooling zone with high speed.

Preferably, the liquefied gas or a mixture of gases in liquid or gaseous form is introduced into the zone of Cooling with a high flow rate.

Especially preferred, it is used as liquefied gas liquefied nitrogen, liquefied hydrogen, helium smoothie or argon liquefied. According to an advantageous execution, it is used as a mixture of liquefied gases a mixture of two or more of the gases aforementioned smoothies.

Especially advantageously, they are added to the liquefied gas or to the mixture of liquefied gases one several components additional. For example, carbon dioxide and / or methane are mixed with the liquefied gas or with the mixture of liquefied gases.

On the device side, the problem raised is resolved by means of a device to cool a Workpiece comprising a cold box with a feed for a cooling medium and a cooling zone to receive the work piece, where the cold box and the area of cooling limit each other and where the power is designed properly for the introduction of liquefied gas or a mixture of liquefied gases, and that is characterized by one or several nozzles are mounted in the cold box so that the cooling medium out of said cold box through the nozzle or nozzles and be driven to the cooling zone through said nozzle or nozzles. Thanks to this configuration it is done it is possible that the cooling medium quickly enters into exchange of heat with the workpiece and that the heat radiation that leave the work piece be picked up by the cold box, presenting the cold box approximately the gas temperature liquefied or liquefied gas mixture.

Preferably, the cold box is provided as equipment to evaporate the liquefied gas or gas mixture smoothies.

Especially preferred, the cold box is configured with a shape adapted to the shape of the piece of work, so that only a very short distance is provided small between the nozzles for the cooling medium and the workpiece surface. The cold box and the area of cooling advantageously limits one another, so that, by one side, the cooling medium that leaves the cold box by nozzles quickly enters heat exchange with the piece of work and, on the other hand, the heat radiation that comes out of the Work piece is picked up by the cold box. The cold box is designed for this purpose preferably so that it surrounds the work piece on several sides.

According to an improvement especially advantageous of the invention, the cold box is subdivided into two or more sections of cold box that are distanced from each other by means of a respective slit present in the area of the nozzles.

In addition, the object of the present invention is the use of the device described above to cool parts of metal work, especially for cooling tubes or others semiproducts such as rods, profiles or wire.

The invention offers a method of extremely effective cooling or sudden cooling, especially for hot metal parts. At high temperatures, heat transmission is mainly carried out by heat radiation According to the invention, the cold box is maintained at Low temperature by the liquefied gas fed. Directly adjacent to the cold box is the cooling zone for Receive the work piece. The temperature difference between the Workpiece surface and cold box is maximized by the cooling of the cold box, so that a optimal cooling by radiation. In addition, the cooling medium is driven to the surface of the workpiece through nozzle openings made in the cold box. This flow causes additional cooling by convection. Together, the invention thus offers an especially efficient use of The different mechanisms of heat transmission.

In the following, the invention and other executions thereof referring to the Examples of embodiment represented in the figures. Show in particular:

Figure 1, a schematic representation of a cold box according to the invention with a work piece,

Figure 2, a schematic representation of a cold box according to the invention that is subdivided into three sections of cold box, and

Figure 3, a sectional representation schematic of figure 2 along A-A.

Figure 1 shows a work piece 1, here a tube 1, which moves along the direction indicated by the arrow 2 through the cold box 3, by which the tube 1. Cold box 3 is adapted to the shape of tube 1. A through feed 4, liquefied gas is continuously introduced, here, for example, liquefied nitrogen, in the cold box 3. According to the needs, the gas still comes out as liquefied gas through the nozzle field formed by nozzles 5 and, using the evaporation heat, comes into action on the surface of the Workpiece 1 as a very cold cooling medium equipped with high flow rate.

In the other case, the cold box 3 acts as evaporator. The heat of evaporation is then used in this case to cool and keep the cold box cold 3.

In both variants the cold box 3 has approximately the temperature of the liquefied gas. This means that the temperature difference between the surface of the piece of work and the surface of the cold box is permanently very large and produces a corresponding cooling of the piece of Work 1 through the radiation mechanism, which is assisted effectively by heat transport as a result of the flow of originally very cold gas 6.

The action of this procedure can be optimized so that the upper limit for the amount of heat  evacuated is no longer determined by the amount of gas fed liquefied and by the thermal properties of this one, but the heat conduction mechanism of workpiece 1 prefix the upper limit.

For the embodiment shown in Figure 1 may indicate the following values by way of example: A steel tube 1 with a diameter of 60 mm and a thickness of 3 mm wall is moved through cold box 3 with a speed of 5 m / s. The starting temperature of the steel tube 1 amounts to 1050 ° C. The final temperature after cooling it amounts, for example, to 700 ° C. This final result is reached. by using liquefied nitrogen as a cooling medium in an amount of 300 kg / h and a feed pressure of 3 pubs. The nozzle field presents here 20 nozzles 5 with a diameter of 3 mm each. The total length of the box Cold 3 amounts to 1200 mm.

Figure 2 shows another embodiment. Cold box 3 is divided here into three sections 8 of it among which exits through the respective slit 7 gas in shape of a gas flow 6. The movement of the workpiece is performs again in the direction indicated by arrow 2. The Workpiece 1 is this example a copper profile 1 with a maximum width of 35 mm, which comes out of an extrusion press with a speed of 100 m / min and a temperature of 750 ° C. The final temperature after cooling should rise to 200 ° C. The copper profile 1 moves through the device shown in figure 2 and then cooled with the help of a mixture of liquefied gases provided through feed 4 and delivered through the nozzles 5 in the different sections 8 of the cold box. Be use liquefied helium here or, as a cheaper variant, a mixture 95% liquefied nitrogen and 5% hydrogen gas. Consumption of gas amounts to 350 kg / h.

Due to the other temperature conditions, the heat transport with the gas flow 6 has in this example more important than in the example in figure 1. To optimize circulation conditions for gas flow 6 and guarantee gas leakage despite very narrow slits 9, it He has divided the cold box 3 into three sections 8 of it. The distance 7 between sections 8 of the cold box can be varied and optimized in accordance with the specific needs of Different application cases.

Figure 3 shows a representation in section of figure 2 along A-A. Here is You can especially appreciate the shape of the cold box 3 adapted to workpiece 1 or that of the section shown 8 of said cold box, thanks to which the nozzles 5 are positioned advantageously always at a constantly small distance 9 of The surface of the workpiece.

Claims (15)

1. Procedure for cooling a workpiece (1), in which the workpiece (1) is introduced into a cooling zone (10) that borders a cold box (3), and into which a cooling medium to the cold box (3), the cooling means comprising a liquefied gas or a mixture of liquefied gases, whose heat of evaporation is used to cool the cold box (3) and to cool the surface of the workpiece (1 ), characterized in that the cooling medium leaves the cold box (3) by one or several nozzles (5) and is led to the cooling zone (10) through said nozzle or nozzles (5). 2. Method according to claim 1, characterized in that the liquefied gas or the mixture of liquefied gases is totally or partially evaporated in the cold box (3), using the heat of evaporation in whole or in part to cool the cold box (3 ). 3. Method according to claim 1 or 2, characterized in that the liquefied gas or the mixture of liquefied gases is totally or partially evaporated in the cold zone (10), using the heat of evaporation in whole or in part to cool the surface of The work piece. Method according to any one of claims 1 to 3, characterized in that the workpiece (1) moves through the cooling zone (10) during cooling. 5. Method according to any of claims 1 to 4, characterized in that the cooling zone (10) is adapted to the shape of the workpiece (1), so that the cooling medium travels only a very small path (9) between the nozzle or the nozzles (5), through which the cooling medium is introduced, and the surface of the workpiece. Method according to any one of claims 1 to 5, characterized in that the liquefied gas or the mixture of liquefied gases is introduced into the cooling zone (10) with a high flow rate. 7. Method according to any one of claims 1 to 6, characterized in that liquefied nitrogen, liquefied hydrogen, liquefied helium or liquefied argon is used as the liquefied gas. Method according to any one of claims 1 to 7, characterized in that a mixture of two or more of the liquefied gases mentioned in claim 7 is used as a mixture of liquefied gases. 9. Method according to claim 7 or 8, characterized in that one or more additional components are added to the liquefied gas or to the mixture of liquefied gases. 10. Method according to claim 9, characterized in that carbon dioxide and / or methane are mixed with the liquefied gas or with the mixture of suitable gases. 11. Device for cooling a workpiece (1), comprising a cold box (3) with a feed (4) for a cooling medium and a cooling zone (10) for receiving the workpiece (1), in where the cold box (3) and the cooling zone (10) limit each other and where the feed (4) is designed properly for the introduction of liquefied gas or a suitable gas mixture, characterized in that one or more nozzles (5) are arranged in the cold box (3) so that the cooling medium comes out of said cold box (3) through the nozzle or nozzles (5) and is led to the cooling zone (10) through said nozzle or nozzles (5). 12. Device according to claim 11, characterized in that the cold box (3) is provided as equipment for evaporating the liquefied gas or the mixture of liquefied gases. 13. Device according to claim 11 or 12, characterized in that the cold box (3) is configured with a shape adapted to the shape of the workpiece (1), so that only a very small distance (9) is provided between the nozzles (5) for the cooling medium and the surface of the workpiece. 14. Device according to any of claims 11 to 13, characterized in that the cold box (3) is subdivided into two or more sections (8) thereof which are distanced from each other by means of a respective slit (7) present in the nozzle area. 15. Use of the device according to any of the claims 11 to 14 for cooling metal work pieces (1), especially for cooling tubes or other semi-finished products as rods, profiles or wire.