WO2023247881A1

WO2023247881A1 - Device for the fluid cooling of a hot surface, and associated press plate or mould

Info

Publication number: WO2023247881A1
Application number: PCT/FR2023/050909
Authority: WO
Inventors: Klaus BÜLOW
Original assignee: Pinette Emidecau Industrie
Priority date: 2022-06-20
Filing date: 2023-06-19
Publication date: 2023-12-28
Also published as: FR3136841A1

Abstract

The invention relates to a cooling device (1) which makes it possible to rapidly and uniformly cool a surface (10) heated to a temperature greater than the evaporation temperature of the cooling fluid. The device comprises at least one assembly of two interlocked tubes (2), with: an inner tube (4) which has openings (8) made in it and which is connected to a liquid inlet (12); and an outer tube (3) which is connected to a vapour outlet (16) and which extends along the surface to be cooled and around the inner tube so as to form, in the outer tube, an intermediate volume (5) around the inner tube. The cooling fluid enters the inner tube in the liquid state and passes through the openings, moving into the intermediate volume where it evaporates. A helical wall (20) is preferably arranged in the intermediate volume, in order to guide the gaseous cooling fluid to the vapour outlet.

Description

DESCRIPTION

TITLE: DEVICE FOR FLUID COOLING OF A HOT SURFACE AND ASSOCIATED PRESS PLATE OR MOLD

Technical area

The present invention relates to a device for cooling a hot, heated or heated surface using a cooling fluid, as many exist in the industry.

Although many applications are possible, the invention is particularly suitable for cooling a press plate or a mold, used for molding or thermoforming plastic or composite materials or for shaping any other high temperature material.

The invention also relates to a press plate or a mold, equipped with such a cooling device.

Prior art

In industry, and in particular in the field of plastics processing or composite materials, parts are commonly used which are heated to high temperatures of several hundred degrees Celsius. These are for example the different parts of a mold used in particular for the molding of plastic materials by injection, blowing or other, or even thermocompression, pressing or stamping plates used in particular for the shaping of composite materials or plastics.

In all of these processes, the step of shaping the material at high temperature is followed by a step of cooling it, in order to give it sufficient rigidity to be able to be demolded without deforming. For this, the plates or mold parts, which are often large and which have previously been heated to a high temperature, for example up to 500°C, must be cooled effectively over their entire surface area.

This cooling must be as rapid as possible, because the duration of the cooling step before ejection of the mold or the press represents a very important and often the majority part of the duration of the manufacturing cycle of a part. A Rapid cooling therefore makes it possible to limit the duration of the manufacturing cycle and thus increase yield and reduce production costs.

However, it is also very important to control this cooling so that it is uniform over the entire surface of the plate or mold part to be cooled. Indeed, non-homogeneous cooling can lead to numerous defects in the products manufactured: appearance defects such as differences in shine depending on the location, structural defects such as deformation, warping or greater fragility of the material in certain areas, or even dimensional defects due to uncontrolled shrinkage of the material which could result in non-compliance with the recommended tolerances.

The cooling device used must therefore not only be very effective to allow rapid cooling of the part to be cooled, but it must also guarantee homogeneous temperature distribution over the entire surface of the plate or mold part to be cooled.

To ensure this type of cooling, networks of tubes are conventionally used, dug inside these plates or molds, in which a cooling fluid is circulated, generally water, oil, or even water and air alternately.

To obtain rapid and uniform cooling, it is often proposed to increase the flow rate of the fluid, lower its inlet temperature, increase the number of tubes or modify their arrangement.

However, even by adjusting all of these parameters, conventional cooling devices are not entirely satisfactory. Indeed, as the temperature of the surface to be cooled is very often much higher than the vaporization temperature of the cooling fluid, the latter quickly evaporates inside the tube when it approaches or comes into contact with the wall of the tube. This sudden evaporation of the cooling fluid results in the formation of vapor bubbles in the tube which hinder the progression of the cooling fluid inside the tube. The cooling speed of the device is reduced and a difference is created between the zones located near the inlet of the cooling fluid and those which are far from it, causing defects in the homogeneity of the cooling.

Document US20200406520, for example, proposes a cooling device in which water is introduced at high pressure into a chamber evaporation via a capillary tube. Since the temperature of the mold core is higher than the evaporation temperature of water, the water contained in the evaporation chamber evaporates, and then the steam is discharged through an outlet pipe. This device can be used to cool a particular point of a mold, but not a surface evenly.

Document JPH06315751A proposes a device for cooling a mold. In this device, a coolant is sent into a chamber via a pipe passing through this chamber. The liquid is sprayed from the pipe towards the chamber via nozzles distributed along the length of the pipe, in order to be distributed evenly in the chamber.

Document JPH09136325 A proposes a similar device, with the addition of a step of reducing the pressure in the chamber, in order to vaporize the coolant.

These solutions do not make it possible to apply sufficiently uniform cooling to a surface.

The technical problem targeted by the invention is therefore to obtain an efficient, rapid cooling device capable of guaranteeing homogeneous cooling over the entire surface of a hot surface.

Presentation of the invention

The invention proposes to respond to this technical problem with a device for cooling a hot surface with a cooling fluid, this hot surface being configured to be brought to a temperature higher than the vaporization temperature of the cooling fluid.

According to the invention, the cooling device comprises:

- at least one liquid inlet configured to introduce the cooling fluid in the liquid state;

- at least one steam outlet configured to extract the cooling fluid in the predominantly gaseous state;

- at least one set of nested tubes comprising:

. an external tube connected to said at least one steam outlet, said external tube being intended to be placed in contact with or near the hot surface,

. an internal tube connected to said at least one liquid inlet and extending to inside the outer tube so as to provide an intermediate volume around the inner tube and inside the outer tube; the internal tube comprising through openings arranged so as to allow the cooling fluid to circulate from the interior of the internal tube towards the intermediate volume to be vaporized there.

For the purposes of the invention, the vaporization temperature of the cooling fluid is defined as that corresponding to the pressure inside the device when it is used.

In addition, the expression “in the predominantly gaseous state” means for the purposes of the invention that more than 50% of the fluid is in the form of gas.

Thanks to this advantageous configuration of the cooling device according to the invention, the flow of cooling liquid is no longer hampered by the transition to the gaseous state of the cooling fluid. In fact, this transformation occurs mainly in the intermediate volume, when the liquid comes into contact with or approaches the hot wall of the external tube. The cooling fluid, which enters the internal tube in the liquid state, remains there in this form and can therefore circulate freely in the internal tube without being hampered by the presence of bubbles. A high flow rate can thus be used to obtain rapid and efficient cooling over the entire length of the tube.

Furthermore, the cooling device according to the invention, which uses and promotes the transition from the liquid state to the gaseous state of the cooling fluid, makes it possible to obtain significant heat absorption due to this change of state, this which further improves the effectiveness of the device.

Thus, while the transition of the cooling fluid from the liquid state to the gaseous state constituted a major disadvantage that those skilled in the art sought to avoid in the cooling devices of the prior art, this change of state is on the contrary sought after and advantageously used by the cooling device according to the invention.

The configuration of the cooling device according to the invention thus makes it possible to obtain rapid, efficient and uniform cooling over the entire surface of the hot surface to be cooled.

Furthermore, the cooling obtained by means of the device according to the invention is perfectly controllable. More or less rapid cooling can thus be obtained depending on the technical needs and wishes of the user. he is also possible for example to produce cooling extending over a long period of time.

According to the invention, the cooling device further comprises a helical wall arranged in the intermediate volume so as to guide the cooling fluid in the predominantly gaseous state towards said at least one steam outlet.

This helical wall which is located in the intermediate volume makes it possible to channel and guide the steam thus formed towards the steam outlet. This phenomenon is accentuated by the continuous arrival of cooling fluid in the liquid state and by the increase in volume of the fluid when it passes into the gaseous state which pushes the gas already present in the intermediate volume towards the outlet. The cooling fluid in the gaseous state is thus evacuated quickly, which further improves the efficiency of the device.

According to one embodiment of the invention, the cooling device comprises at least two liquid inlets, configured to introduce the cooling fluid in the liquid state, and each being connected to a separate end of the internal tube.

Thanks to these two liquid inlets, it is possible to enter the coolant simultaneously at each of the two ends of the internal tube, which allows better homogenization of the temperature over the entire length of the surface to be cooled.

According to one embodiment of the invention, the cooling device comprises at least two steam outlets, configured to extract the cooling fluid in the predominantly gaseous state, and each being connected to a separate end of the external tube.

Thanks to these two steam outlets, the cooling fluid in the predominantly gaseous state can be extracted more easily and quickly through both ends of the external tube simultaneously. Cooling efficiency is improved.

According to one embodiment of the invention, the cooling device comprises at least one air inlet connected to one of the ends of the internal tube or the external tube, configured to introduce air or another gas into the tube to which it is connected. Thanks to such an air inlet, it is possible to purge the device, for example between each cycle of use of the hot surface, or to alternate cooling sequences during which cooling fluid is successively circulated. cooling in liquid or air state.

According to one embodiment of the invention, the cooling device comprises at least one evacuation outlet, connected to one of the ends of the internal tube.

This outlet is configured to extract the cooling fluid in the liquid or gaseous state or in the liquid/gas mixture state, or to extract air or another gas.

Such an outlet thus makes it possible to evacuate the part of the coolant which has not passed through the openings of the internal tube, or the gas used to purge the device, or even the coolant used at the very beginning of a cycle. cooling to cool the inner tube.

According to one embodiment of the invention, the openings of the internal tube have a variable surface area and/or shape and/or a distance between two consecutive openings that varies along the length of the internal tube.

By thus locally modifying the arrangement, distribution, shape and/or surface area of the openings of the internal tube, those skilled in the art can locally increase or decrease the quantity of cooling liquid which passes through the wall towards the intermediate volume of the tube. external. It can thus obtain better homogenization of the temperature of the hot surface during cooling by adapting it to the particular needs of each installation.

According to another embodiment of the invention, the cooling device comprises several sets of juxtaposed nested tubes. The sets of nested tubes can thus be distributed over the entire surface of the hot surface to be cooled for better uniformity of cooling.

According to a preferred variant of this embodiment, the cooling device can further comprise an inlet distributor which supplies several liquid inlets of the different sets of juxtaposed nested tubes, and an outlet collector connected to several steam outlets of the different sets of juxtaposed nested tubes. This inlet distributor and this outlet collector are preferably connected respectively to all of the liquid inlets and to all of the steam outlets located on the same side of the sets of nested tubes.

According to one embodiment of the invention, the inlets and outlets of the cooling device are equipped with valves which can be alternately opened or closed.

According to one embodiment of the invention, the cooling device further comprises a safety valve with manual or automatic opening, connected to one of the ends of the external tube. Such a safety valve advantageously makes it possible to release the steam contained in the external tube when the pressure is too high inside it.

According to one embodiment of the invention, the cooling device may further comprise temperature sensors and a regulation device which regulates the inlet flow of the cooling fluid and the opening or closing of the valves as a function of the temperature measured by the temperature sensors. The cooling device can thus be advantageously controlled and regulated automatically.

The invention also teaches the use of a cooling device according to the invention to cool a plate or a mold.

The cooling device according to the invention can thus be used to cool all kinds of standard heated or heated plates or mold parts without it being necessary to make significant modifications to them. Indeed, the cooling device according to the invention can simply be positioned against the plate or the part to be cooled, without modifying it. Alternatively, the sets of nested tubes of the cooling device can be provided directly in the mass of the plate or part to be cooled, for better cooling efficiency.

The invention thus teaches a press plate or a mold, heated or heated, comprising a cooling device according to the invention.

Brief description of the figures

Other characteristics and advantages of the invention will appear on reading the detailed description which follows, description made with reference to the appended drawings, in which: [Fig 1] is a schematic plan representation of an example of a cooling device according to the invention;

[Fig 2] is a perspective view of an example of a cooling device according to the invention which comprises only a single set of nested tubes;

[Fig 3] is a perspective view of another example of a cooling device according to the invention which comprises several sets of juxtaposed nested tubes;

[Fig 4] is a perspective view of an example of a heating plate incorporating a cooling device with several sets of juxtaposed nested tubes;

[Fig 5] is a cross-sectional view of the heating plate of Figure 4, the central part of which has been truncated, section made at the level of one of its sets of nested tubes;

[Fig 6] [Fig 7] [Fig 8] [Fig 9] Figures 6 to 9 are schematic plan views which illustrate successive stages of operation of the cooling device of Figure 1, during an example of a method of heating then cooling a hot surface incorporating this device.

Detailed description of the invention

The cooling device according to the present invention will now be described in detail with reference to Figures 1 to 9. The equivalent elements represented in the different figures will bear the same numerical references.

A first example of a cooling device 1 according to the invention has been shown schematically in Figure 1.

As stated previously, the cooling device 1 comprises a set of nested tubes 2, which comprises an external tube 3 inside which an internal tube 4 extends, preferably substantially in the same longitudinal direction. An intermediate volume 5 is thus provided around the internal tube 4 and inside the external tube 3.

The internal tube 4 and the external tube 3 are preferably coaxial as shown in the different figures. However, other arrangements are also possible, the internal tube not being able to be arranged in the center of the external tube, but for example being closer to the wall 6 of the external tube on one side than on the other. Furthermore, the relative arrangement of the internal tube 4 relative to the external tube 3 is not necessarily identical over the entire length of the set of nested tubes 2 and can vary locally according to needs.

The wall 7 of the internal tube 4 has a series of through openings 8, which communicate the interior volume 9 of the internal tube 4 with the intermediate volume 5. The number, size, shape and arrangement of these openings 8 can be arbitrary and will be determined by those skilled in the art according to the specific cooling needs of the intended application. Those skilled in the art will thus be able to easily adapt the number, size, shape and distribution of these openings according to specific localized cooling needs, in particular depending on the particular characteristics of the hot surface to be cooled, for example its shape. , its size, its temperature and local constraints which can induce different cooling needs locally.

In the examples of embodiments shown, these openings 8 are of the same size and distributed regularly over the entire length of the set of nested tubes 2 located in contact with the hot surface 10 to be cooled. Another embodiment not shown could for example include openings 8 whose number and/or diameter would gradually increase towards the central zone of the set of nested tubes 2, to improve the cooling in this zone despite the progressive warming of the cooling fluid. Many other suitable arrangements could be imagined by those skilled in the art.

Likewise, these openings 8 are not necessarily circular, although this is a preferred shape. They may have any suitable shape, for example that of an elongated slot.

The internal tube 4 has two ends 11, at least one of which is connected to a liquid inlet 12 through which the cooling fluid in the liquid state can be introduced. Although this is not obligatory, in the preferred examples shown in the figures, each of these ends 11 is connected to a liquid inlet 12.

Advantageously, one of these ends 11 can also be connected to an air inlet 13 and/or to an evacuation outlet 14 through which the liquid or gas contained in the internal tube 4 can escape. This air inlet 13 and this evacuation outlet 14 are each preferably connected to a separate end 11 of the internal tube. In the same way, the external tube 3 has two ends 15, at least one of which is connected to a steam outlet 16 through which the cooling fluid in the predominantly gaseous state can escape. Preferably and as shown, each of the ends 15 of the external tube 3 can be connected to a steam outlet 16 in order to facilitate this evacuation. The external tube 3 is preferably also connected by one of these ends 15 to an air inlet 13 and/or to a safety outlet 17 which makes it possible to evacuate any excess steam present in the set of nested tubes 2 in order to reduce the pressure inside the device. As previously, this air inlet 13 and this safety outlet 17 are preferably each connected to a separate end 15 of the external tube 3.

Each of these liquid inlets 12, air inlets 13, evacuation outlet 14 and steam outlets 16 is preferably equipped with a valve 18 which can be placed in the open position or in the closed position, in order to respectively allow or s oppose the passage of liquid or gas through this valve 18 and thus authorize or prohibit the entry or exit of fluid into or out of the set of nested tubes 2. These valves 18 can be automatic or manual. These can be simple valves with two positions: open or closed (On/Off valves), or more sophisticated valves such as proportional valves, adjustable in pressure and/or flow.

The safety outlet 17 is preferably equipped with a safety valve 19, manual or automatic, which serves as a safety valve to protect the cooling device 1 and the operators who operate it, from uncontrolled internal overpressure linked to too much steam which could lead to an explosion. This safety valve 19 prevents the interior volume 9 of the internal tube 4 and the intermediate volume 5 of the external tube 3 from forming a completely closed chamber, which could present a safety risk. Advantageously, this safety valve 19 can be a valve which opens automatically when the internal pressure reaches a threshold value considered dangerous, for example between 5 and 10 bars. In the event of a malfunction, this valve automatically opens to release the compressed steam and lower the internal pressure. It thus improves the security of the device. Alternatively, this safety valve 19 can be left open permanently or can be opened manually by the operator if he notices an abnormal increase in pressure inside the device. The cooling device 1 shown further comprises a helical wall 20, placed in the intermediate volume 5 and which makes it possible to guide the cooling fluid located in this intermediate volume 5 towards the steam outlet(s) 16.

An embodiment without helical wall 20 is nevertheless possible.

Depending on the variants, the orientation angle and the pitch of the helical wall 20 can be any and different from those shown. These parameters will be chosen by those skilled in the art according to the speed at which he wishes the cooling fluid to be channeled towards the steam outlet 16. Indeed, by modifying the pitch and/or the inclination of the propeller , those skilled in the art will be able to increase or reduce the path traveled by the cooling fluid to the steam outlet 16 and thus optimize the contact time between the cooling fluid and the hot surface 10.

In order to further improve this effect, it can even be envisaged that the pitch and/or the angle of inclination of the helical wall 20 are not constant over its entire length, but evolve, for example, gradually as they approach the outlet. steam 16.

In the case where the cooling device 1 comprises two steam outlets 16, each arranged at one of the ends of the external tube 15, it is also possible that the direction of inclination of the helical wall 20 is not the same on its entire length, the helical surface 20 can thus comprise two distinct sections each having a different direction of inclination so as to guide the cooling fluid towards a different steam outlet 16.

The cooling device 1 is intended to cool the hot surface 10 which can take different shapes depending on needs. It may be for example an elongated element 21, for example cylindrical or parallelepiped like that shown in Figures 1 and 2, or even a more extended element, for example a plate 22 as shown in Figures 3 to 5. Many other shapes are obviously possible depending on the applications.

The cooling device 1 according to the invention can be placed against or near the hot surface 10 to be cooled. For better cooling efficiency, the set of nested tubes 2 of the cooling device 1 can extend directly inside the part to be cooled. It can thus for example, as shown, be placed inside a conduit 24 directly provided in the mass of the part to be cooled. Of course, the conduit 24, like the set of nested tubes 2, is not necessarily rectilinear but has a layout adapted to the shape of the part to be cooled and the thermal constraints that must be respected to obtain satisfactory cooling.

The cooling device 1 according to the invention is not limited to a single set of nested tubes 2. Indeed, depending on the size and/or shape of the part to be cooled, the cooling device 1 can comprise several sets of nested tubes 2 juxtaposed, thus being able to be distributed over the entire surface area of the hot surface 10 to be cooled. Good uniformity of cooling can thus be advantageously obtained. An example of such an embodiment with several sets of juxtaposed nested tubes 2 has been shown in Figures 3 to 5. In this example, the part to be cooled is a plate 22 of rectangular shape which is heated by fifteen heating tubes 23 parallel. The conduits 24 have been provided between the heating tubes 23. They extend parallel to each other, over the entire length of the plate 22 and open out on both sides of the plate 22. A set of nested tubes 2 as described previously is engaged in each of these conduits 24, thus forming the cooling device 1.

Each of these sets of nested tubes 2 comprises an internal tube 4 connected at each of its ends 11 to a liquid inlet 12, and an external tube 3 connected at each of its ends 15 to a steam outlet 16. The ends 11 of each of the internal tubes 4 are also connected to an air inlet 13, which in particular allows the device to be purged by introducing air which can circulate in the internal tube 4, pass through the openings 8, circulate in the external tube 3, then be evacuated through the steam outlets 16.

In order to limit the piping necessary for the operation of such a cooling device 1 with multiple sets of nested tubes 2, collective connection devices can advantageously be used to supply all of the nested tubes. Thus for example, one or more inlet distributors 25 and/or one or more outlet collectors 26 can be connected to all of the ends 11 of the internal tubes 4 or to all of the ends 15 of the external tubes 3, opening out on the same side of the plate 22. These inlet distributors 25 or outlet collectors 26 are for example fluid supply or discharge tubes to which all of the ends 11 or 15 are connected. The cooling device 1 shown in Figures 3 to 5 thus comprises for example two liquid inlet distributors 27, each located on one side of the plate 22 and which each supply cooling liquid to all of the liquid inlets 12 of the ends 11 located on the same side of the plate 22. It also includes two air inlet distributors 28, each located on one side of the plate 22, and which are also each connected to all of the ends 11 internal tubes 4 opening out on the same side of the plate 22, in order to supply air to all of their air inlet 13.

In the same way, two steam outlet collectors 29 each extend on one side of the plate 22 and are each connected to all of the ends 15 of the external tubes 3 opening on the same side of the plate 22, in order to collect and evacuate the cooling fluid in the predominantly gaseous state escaping from their steam outlets 16.

An example of operation of a cooling device 1 according to the invention will now be described with reference to Figures 6 to 9. Of course, this example is not limiting and a different operating method of this device could be implemented. work by a person skilled in the art.

In these figures, the liquid inlets and outlets have been represented schematically by thick black arrows 30, and the gas inlets and outlets have been symbolized by thick white arrows 31.

For the purpose of simplification, the cooling device 1 shown in these figures only comprises a single set of nested tubes 2. Those skilled in the art will obviously be able to adapt this process without difficulty to a cooling device with several sets of nested tubes 2 juxtaposed.

To describe the successive stages of the process, the positions of the different valves of the system will be indicated below at each stage. Depending on the variants of the cooling device, the operation of these valves to go from an open to closed position or vice versa can be carried out manually or automatically controlled by a regulation system 32, following a pre-established programming or depending on the measurement results. carried out by a set of sensors 33 preferentially distributed over the hot surface 10 to be cooled. Depending on the variants, the valves 18 may adopt, in addition to a completely open or completely closed position, intermediate positions partially open in order to regulate the flow rate and/or the inlet pressure of the different fluids in the set of nested tubes 2.

In Figures 6 to 9, the safety valve 19 of the safety outlet 17 has been shown in the open position. It can be left permanently in this position for safety reasons. Alternatively, if this valve is a safety valve opening automatically in the event of overpressure, this valve can be left in the closed position.

The first step of this example process is illustrated in Figure 6. This step takes place prior to heating the hot surface 10 and consists of purging the device using a flow of air blown through it. , so that it can be dried and removed any residual coolant that may have remained from a previous cooling cycle. We thus wish to eliminate any remaining stagnant liquid which could subsequently harm or locally influence thermal absorption and hinder cooling control.

For that, :

- the valves 18 of the liquid inlets 12 connected to the ends 11 of the internal tube 4 are placed in the closed position;

- the valves 18 of the air inlets 13 connected to the end 11 of the internal tube 4 and to the end 15 of the external tube 3 are placed in the open position;

- the valve 18 of the steam outlet 16 connected to the inlet 15 of the external tube 3 located on the same side as the air inlet 13, is placed in the closed position;

- on the other side of the device, the valves 18 of the evacuation outlet 14 connected to the end 11 of the internal tube 4 and of the steam outlet 16 connected to the end 15 of the external tube 3 are placed in position opened.

Air, represented by arrows 31, is then injected through the air inlets 13 of the inner tube 4 and the outer tube 3. It circulates throughout the device before being evacuated by the evacuation outlet 14 of the internal tube 4, the steam outlet 16 of the external tube 3 and possibly the safety outlet 17 of the external tube 3. By its passage along the entire nested tube 2, the injected air carries with it towards the entire outlet trace of residual coolant which may have stagnated in the device since a previous cooling cycle and which could disrupt the new heating then cooling cycle. Once the drying step is completed, the next step shown in Figure 7 corresponds to the heating of the hot surface 10.

During this step, all the valves 18 of the cooling device 1 are placed in the closed position, with the possible exception of the safety valve 19. Thus, the liquid inlets 12, the air inlets 13, the steam outlets 16 and the evacuation outlet 14 are closed and no fluid can enter or leave the device with the exception of a possible gas outlet through the safety outlet 17 in the event of dangerous overpressure. The heating of the surface 10, carried out for example by means of the heating tubes 23, can then begin until reaching the final heating temperature planned over the entire surface area of the surface 10, for its use for example as a mold or thermoforming plate. .

When the use of the hot surface 10 at high temperature is finished and cooling is desired, we begin by cooling the internal tube 4 by circulating cooling liquid through it. The cooling device 1 is then placed in the following configuration, illustrated in Figure 8:

- the valve 18 of the liquid inlet 12 connected to one of the ends 11 of the internal tube 4 is placed in the open position, while the valve 18 of the air inlet 13 connected to the same end 11 of the tube internal is placed in the closed position;

- on the other side of the internal tube 4, the valve 18 of the liquid inlet 12 is placed in the closed position, while the valve 18 of the evacuation outlet 14 is placed in the open position;

- the valves 18 of the steam outlets 16 connected to the ends 15 of the external tube 3 are placed in the closed position;

- the valve 18 of the air inlet 13 connected to the end 15 of the external tube 3 is placed in the open position.

Cooling liquid symbolized by the arrow 30 is introduced through the liquid inlet 12, the valve 18 of which is open. It enters the internal tube 4 which it crosses to exit via the evacuation outlet 14 connected to the other end 11 of the internal tube 4. The cooling liquid thus gradually lowers the temperature of the internal tube 4.

Simultaneously, air, symbolized by arrow 31, is introduced through the air inlet

13 connected to the end 15 of the external tube 3 and circulates in the intermediate volume 5 of the external tube 3 up to the safety outlet 17 through which it is evacuated. This circulation of air in the intermediate volume 5 makes it possible to produce an insulating layer between the internal tube 4 in which the cooling fluid circulates and the hot surface 10. In addition, this circulation of air in the intermediate volume 5 opposes the passage of too large a quantity of cooling liquid through the openings 8 of the wall 7 of the internal tube, the cooling liquid thus remaining mainly in the internal tube 4 to cool it.

Once the internal tube 4 has cooled, the step of cooling the hot part

10 can begin. For this, the cooling device 1 is placed in the configuration shown in Figure 9, in which:

- the valves 18 of the liquid inlets 12 connected to the two ends 11 of the internal tube 4 are placed in the open position;

- the valves 18 of the air inlet 13 and the exhaust outlet 14 connected at the ends

11 of the internal tube 4 are placed in the closed position;

- the valve 18 of the air inlet 13 connected to the end 15 of the external tube 3 is placed in the closed position;

- the valves 18 of the steam outlets 16 connected to the ends 15 of the external tube 3 are placed in the open position.

To obtain controlled and homogeneous cooling of the hot surface 10, the cooling fluid is introduced in the liquid state through the liquid inlets 12 communicating with the ends 11 of the internal tube 4. The cooling fluid then flows to the interior of the internal tube 4 and passes through the openings 8 of its wall 7 to access the intermediate volume 5. When it approaches or comes into contact with the wall 6 of the external tube which is against the hot surface 10, the fluid of cooling vaporizes by absorbing a large quantity of heat, which allows the hot surface 10 to be cooled effectively. The cooling fluid in the predominantly gaseous state is then guided by the helical wall 20, towards the steam outlets 16 located at the ends 15 of the external tube 3 through which it escapes out of the cooling device 1. The circulation of the cooling fluid in the liquid state in the interior volume 9 of the internal tube 4 is not hampered by the appearance of bubbles, because most of the vaporization occurs in the intermediate volume 5. On the contrary, the passage of the coolant from liquid to gaseous state is particularly advantageous because this change of state makes it possible to absorb a large quantity of energy and thus effectively cool the hot surface 10.

This step can be continued until the hot surface 10 has reached the desired cooling temperature.

We can also consider slightly modifying this cooling step depending on the temperature of the hot surface 10.

As long as the temperature of the hot surface 10 is very high, for example between 450 and 350° C., one may want to start with slower cooling so that it can be controlled. For this, it is possible, for example, to use only one water inlet 12 to introduce the cooling fluid in the liquid state through only one of the ends 11 of the internal tube 4, the valve 18 of the liquid inlet 12 located on the other side of the internal tube 4 being left in the closed position. In this case, the valve 18 of the evacuation outlet 14 connected to the internal tube 4 and located on the same side as the closed liquid inlet 12, will be left open as in the configuration of Figure 8.

Once the cooling has been initiated and the temperature of the hot surface 10 has reached a lower value, for example less than 350° C., it may be desired to accelerate the cooling by causing the cooling fluid to enter the liquid state. by both sides of the device as described previously and illustrated in Figure 9.

Preferably, the speed and homogeneity of the cooling of the surface 10 over its entire surface area will be controlled by means of the temperature sensors 33 and the flow rate and/or pressure of the cooling liquid entering the cooling device 1 will be modified accordingly. consequently, for example by modifying the degree of opening of the valves 18 of the liquid inlets 12 if they are proportional valves.

It can also be envisaged to alternate cooling phases as described above during which cooling liquid is circulated in the cooling device 1 and blowing phases during which air is circulated in the device. cooling 1. In this case, during the blowing phases, the valves 18 of the two liquid inlets 12 connected to the ends 11 of the internal tube 4 are placed in the closed position, while the valves 18 of the air inlets 13 connected to the end 11 of the internal tube 4 and the end 15 of the external tube 3 are placed in the open position. The valves 18 of the steam outlets 16 and the exhaust outlet 14 are left in the open position.

The cooling liquid used with the cooling device 1 according to the invention may be different depending on the applications and the heating temperature of the hot surface 10 to be cooled. It is preferably chosen so as to obtain the desired vaporization effect. It is thus possible to preferably use water as a cooling fluid. Other fluids making it possible to obtain such a liquid/vapor phase transition can also be used, in particular liquid nitrogen or another liquefied gas even if this is more expensive than water. Although less efficient, the cooling device according to the invention can also be used with a cooling fluid remaining in a liquid or gaseous state throughout the cooling process. Air or a gas such as nitrogen, carbon dioxide or carbon monoxide can thus be used as a cooling fluid, but with lower cooling efficiency. An oil remaining in a liquid state could also be used with continuous flow as a heat transfer fluid.

Claims

1. Device for cooling (1) a hot surface (10) by a cooling fluid, said hot surface (10) being configured to be brought to a temperature higher than the vaporization temperature of the cooling fluid, said device for cooling (1) comprising:

- at least one liquid inlet (12) configured to introduce the cooling fluid in the liquid state;

- at least one steam outlet (16) configured to extract the cooling fluid in the predominantly gaseous state;

- at least one set of nested tubes (2) comprising:

. an external tube (3) connected to said at least one steam outlet (16), said external tube (16) being intended to be placed in contact with or near the hot surface (10),

. an internal tube (4) connected to said at least one liquid inlet (12) and extending inside the external tube (3) so as to provide an intermediate volume (5) around the internal tube (4) and inside the outer tube (3); the internal tube (4) comprising through openings (8) arranged so as to allow the cooling fluid to circulate from inside the internal tube (4) towards the intermediate volume (5) to be vaporized there.

- a helical wall (20) arranged in the intermediate volume (5) so as to guide the cooling fluid in the predominantly gaseous state towards said at least one steam outlet (16).

2. Cooling device (1) according to claim 1, characterized in that it comprises at least two liquid inlets (12), configured to introduce the cooling fluid in the liquid state, and each being connected to one end (11) distinct from the internal tube (4).

3. Cooling device (1) according to any one of the preceding claims, characterized in that it comprises at least two steam outlets (16), configured to extract the cooling fluid in the predominantly gaseous state, and being each connected to a separate end (15) of the external tube (3).

4. Cooling device (1) according to any one of the preceding claims, characterized in that it comprises at least one air inlet (13), connected to one of the ends (11) of the internal tube (4 ) or one of the ends (15) of the external tube (3), and configured to introduce air or another gas into the tube (3, 4) to which it is connected.

5. Cooling device (1) according to any one of the preceding claims, characterized in that it comprises at least one evacuation outlet (14), connected to one of the ends (11) of the internal tube (4 ).

6. Cooling device (1) according to any one of the preceding claims, characterized in that the openings (8) of the internal tube have a variable surface area and/or shape and/or distance between two consecutive openings (8). along the length of the internal tube (4).

7. Cooling device (1) according to any one of the preceding claims, characterized in that it comprises several sets of juxtaposed nested tubes (2).

8. Cooling device (1) according to the preceding claim, characterized in that it further comprises an inlet distributor (25) which supplies several liquid inlets (12) of sets of juxtaposed nested tubes (2), and an outlet manifold (26) connected to a plurality of steam outlets (16) of nested tube assemblies

(2) juxtaposed.

9. Cooling device (1) according to any one of the preceding claims, characterized in that the inlets (12, 13) and the outlets (14, 16) are equipped with valves (18) which can be alternately opened or closed .

10. Cooling device (1) according to any one of the preceding claims, characterized in that it further comprises a safety valve (19) with manual or automatic opening, connected to one of the ends (15) of the outer tube

(3).

11. Cooling device (1) according to claim 9, characterized in that it further comprises temperature sensors (33) and a regulation system (32) which regulates the inlet flow rate of the cooling fluid and the opening or closing of the valves (18) as a function of the temperature measured by the temperature sensors (33).

12. Press plate or mold, heated or heated, characterized in that said press plate or said mold comprises a cooling system (1) according to any one of claims 1 to 11.