Inlet transition chamber for a vacuum chamber of a mobile strip vacuum treatment plant and method thereof

Abstract

The invention relates to an inlet transition chamber for a vacuum chamber (4) of a mobile strip (2) vacuum treatment installation, of the type comprising at least one liquid reservoir (5) containing a liquid (11), the reservoir comprising an upstream compartment (6) and a downstream compartment (7), the upstream compartment (6) and the downstream compartment (7) being separated by a vertical partition (8) leaving an unobstructed passage (9) between the two compartments at the lower part of the reservoir, a guide roller (10) for guiding the strip being arranged in the passage (9). The transition chamber comprises a downstream evacuation chamber (13) extending from the downstream compartment (7) and connected to an evacuation device (15), liquid extraction means (17) being arranged in the downstream evacuation chamber (13), wherein the downstream evacuation chamber comprises an outlet slit (14) for the strip, and wherein the transition chamber comprises means (12) for cooling the liquid (11) contained in the reservoir.

Description

Technical Field

[0001] This invention relates to an inlet transition chamber for a vacuum chamber in a mobile strip vacuum processing equipment. Background Technology

[0002] Processing methods for vacuum treatment of strips, particularly metal strips, are known, which involve moving the strip in a vacuum to expose it to plasma or any other physical phenomenon capable of acting on the strip surface. In all these methods, the movement of the strip is achieved by circulating it between an uncoiler and a winding device.

[0003] In some equipment, the uncoiler and coiler are located inside a vacuum chamber. This arrangement has several disadvantages. On the one hand, the vacuum chamber must be large enough to accommodate the uncoiler and coiler for large rolls of strip, and subsequently, each time the roll is changed, the vacuum must be broken to allow the installation of a new coiler, which means the vacuum must be re-established afterward.

[0004] There are also devices where the uncoiler and coiler are located outside the vacuum chamber, with the strip penetrating into the interior of the vacuum chamber via a transition chamber that forms a seal between the outside atmosphere and the low-pressure atmosphere inside the vacuum chamber at the outlet, through which the strip also passes. For this purpose, known transition chambers comprise multiple depressurization stages arranged in series and separated by rollers that clamp the moving strip. Each depressurization stage is connected to a pump assembly. The disadvantage of this arrangement is that it requires mechanically precise tolerances to minimize leakage between two consecutive depressurization stages and requires relatively high pumping capacity. Therefore, this type of transition chamber incurs high investment costs.

[0005] FR-A-586 866 also describes a seal located at the inlet of a vacuum chamber in an apparatus for continuous processing of metal strip, wherein the seal is formed by a bath of molten metal into which the strip is immersed. The molten metal bath is divided into two compartments: an upstream compartment and an outlet compartment separated by an intermediate partition, wherein the outlet compartment communicates with the vacuum chamber. This apparatus, for example using a molten liquid such as indium, is only suitable for processing strip at a sufficiently high temperature to maintain the molten metal bath at a temperature above the metal's melting point. This temperature may be relatively high, and typically requires means for heating the molten metal bath and optionally heating the strip at the apparatus inlet, particularly when the strip being processed is initially at ambient temperature. It also assumes that the strip can be heated without adversely affecting its properties. Finally, the molten metal used may cause environmental pollution problems and is expensive. Summary of the Invention

[0006] The object of the present invention is to eliminate these disadvantages by providing a transition chamber for vacuum processing of metal strips or polymer films, wherein the transition chamber is located at the entrance of the vacuum processing chamber, which is more economical than a transition chamber with a decompression stage separated by a mechanical seal, and which does not require heating of the strip before it enters the device.

[0007] For this purpose, the present invention relates to an inlet transition chamber for a vacuum chamber of a mobile strip vacuum processing apparatus. This transition chamber is of the type comprising at least one liquid reservoir containing liquid, the reservoir including an upstream compartment and a downstream compartment separated by a vertical partition. This vertical partition creates an unobstructed passage between the two compartments at the lower part of the reservoir, in which rollers for guiding the strip are positioned. The transition chamber includes a downstream evacuation chamber extending from the downstream compartment and connected to an evacuation device, in which a liquid extraction device is positioned. The downstream evacuation chamber includes an outlet slit for the strip. It also includes means for cooling the liquid contained in the reservoir.

[0008] The transition chamber may include multiple liquid storage tanks arranged in series, with the upstream and downstream compartments of two adjacent liquid storage tanks connected at their upper parts by an intermediate evacuation chamber, which has guide rollers for metal strips and is connected to an evacuation device.

[0009] The evacuation device for the intermediate evacuation chamber includes, for example, a pump and an adjustable calibration leak.

[0010] At least two liquid storage tanks may include devices for cooling the liquid.

[0011] Preferably, the outlet slit of the downstream extraction chamber may include a roller seal consisting of two rollers adapted to clamp the moving metal strip.

[0012] The extraction device connected to the downstream extraction chamber may include a condenser.

[0013] The pumping device connected to the downstream pumping chamber preferably includes a device for adjusting the pump discharge rate.

[0014] The liquid extraction device includes, for example, at least two squeeze rollers.

[0015] The transition chamber also includes a thermal drying device located downstream of the liquid extraction device in the direction of strip movement.

[0016] Downstream of the downstream extraction chamber, the transition chamber may include at least one roller transition chamber.

[0017] At least one roller transition chamber located downstream of the extraction chamber may include the injection of dry gas.

[0018] The liquid in one or more storage tanks is preferably water.

[0019] The present invention also relates to a method comprising an inlet transition chamber according to the invention to ensure a seal at the inlet of a vacuum treatment housing for continuously moving strips.

[0020] According to this method, liquid is pumped into a downstream pumping chamber to maintain a pressure below atmospheric pressure, and the fluid contained in the downstream reservoir is maintained at a temperature below the temperature at which the fluid's saturated vapor pressure is equal to the pressure maintained in the downstream pumping chamber.

[0021] When the squeezing device in the inlet transition chamber includes a heat drying device, the strip is heated, and the liquid remaining on the surface of the strip after squeezing is heated to a temperature higher than the condensation temperature of the liquid under the pressure maintained in the downstream evacuation chamber.

[0022] The strip is, for example, a metal strip.

[0023] The strip can also be composed of at least one polymer film. Attached Figure Description

[0024] The invention will now be described in more detail, but not limitingly, with reference to the accompanying drawings, in which:

[0025] - Figure 1 This is a schematic cross-sectional view of a hydraulic transfer chamber for low-vacuum applications, including a reservoir.

[0026] - Figure 2 This is a schematic cross-sectional view of a hydraulic transfer chamber for low-vacuum applications, including two liquid reservoirs.

[0027] - Figure 3 This is a schematic cross-sectional view of a hydraulic transfer chamber for low-vacuum applications, which includes a reservoir located at the inlet of a vacuum chamber used for processing products requiring drying.

[0028] - Figure 4 This is a front view of a hydraulic transfer chamber for low-vacuum applications, which includes two reservoirs located at the inlet of a vacuum chamber used for processing products requiring drying.

[0029] - Figure 5 This is a schematic cross-sectional view of a hydraulic transfer chamber including a reservoir, which is suitable for installation at the inlet of a vacuum chamber capable of depressurization to below 1 Pa.

[0030] - Figure 6 This is a schematic cross-sectional view of a hydraulic transition chamber including two reservoirs, which is adapted to be installed at the inlet of a vacuum chamber for performing the method at a pressure of less than 1 Pa.

[0031] In different accompanying drawings, the same elements are identified by the same reference numerals. Detailed Implementation

[0032] Figure 1 The hydraulic transition chamber, generally designated 1, for low-vacuum applications, is the inlet transition chamber of the vacuum chamber of a vacuum processing device for moving strip 2 between the external atmosphere 3 and the internal atmosphere 4 of the vacuum chamber. The interior 4 of the vacuum chamber is under a pressure of tens of millibars (tens of hectopascals). The hydraulic transition chamber includes a reservoir 5, which is divided into an upstream compartment 6 and a downstream compartment 7 by a vertical partition. The partition, at its lower portion, leaves an unobstructed passage 9 between the upstream inlet compartment 6 and the downstream outlet compartment 7. At its lower portion, within the passage between the upstream compartment 6 and the downstream compartment 7, it includes guide rollers 10 for the strip 2. Furthermore, the reservoir is connected to a device 12, which is designed to supply liquid to the reservoir on one hand and cool the liquid 11 contained within it on the other. This cooling device can, for example, consist of a suction and recirculation loop, which, for example, allows the liquid to flow through a cooling coil.

[0033] At its upper part, the downstream compartment 7 extends from the downstream evacuation chamber 13, which is separated from the interior of the vacuum housing 4 by an outlet slit 14, which is composed of a guide roller 14A for the strip 2 and a complementary roller 14B designed to clamp the strip against the guide roller. The downstream evacuation chamber 13 is connected to an evacuation device 15, which is composed of a pump 15A and a condenser 16. Inside the downstream evacuation chamber 13, a squeezing device, composed of two squeezing rollers 17A and 17B designed to clamp and wipe the strip 2, is positioned at the interface between the downstream compartment 7 of the liquid storage tank and the evacuation chamber 13.

[0034] The operation of the apparatus used as the inlet transition chamber for a vacuum processing device operating at pressures of tens of hundreds of Pascals is described below.

[0035] Air is evacuated from the downstream evacuation chamber 13 using an evacuation device 15 to establish a pressure slightly lower than the pressure to be maintained in the processing chamber. Due to the pressure difference between the evacuation chamber 13 and the external atmospheric pressure, a liquid level difference h appears in the storage tank 5 between the downstream compartment 7 and the upstream compartment 6. The liquid level in the downstream compartment is higher than the liquid level in the upstream compartment, and this level difference corresponds to the difference between atmospheric pressure and the pressure in the downstream evacuation chamber. Since the pressure in the downstream evacuation chamber is lower than atmospheric pressure, the pressure difference is practically equal to atmospheric pressure, and therefore the liquid level difference between the downstream and upstream compartments is practically equal to the height of the liquid column corresponding to atmospheric pressure. For water, this liquid column is approximately 10 meters. Those skilled in the art will understand that if the liquid used is of a different density than water, the height of the liquid column will be different because it is inversely proportional to the density of the liquid.

[0036] In all cases, the height of the equipment must be sufficient to allow for a liquid level difference between the upstream and downstream compartments corresponding to the pressure difference. Therefore, the aforementioned equipment can only be used in locations with a large clearance height.

[0037] In addition, in order to limit the evaporation of the liquid in the downstream extraction chamber, it is desirable to keep the temperature of the liquid in the downstream compartment of the storage tank below the temperature at which the saturated vapor pressure of the liquid is equal to the pressure maintained in the downstream extraction chamber 13.

[0038] For example, when the liquid is water and the pressure in the downstream extraction chamber is 100 hPa, the water temperature must be maintained below approximately 45°C to keep the saturated vapor pressure below 100 hPa. Similarly, when the pressure in the extraction chamber is approximately 500 hPa, a water temperature below approximately 80°C is sufficient to keep the saturated vapor pressure below 500 hPa. Conversely, when the pressure in the extraction chamber is approximately 10 hPa, the water temperature required to keep the saturated vapor pressure below 10 hPa is approximately -4°C.

[0039] When the temperature of the liquid is below the temperature corresponding to the saturated vapor pressure maintained in the downstream pumping chamber, evaporation of the liquid is virtually zero. On the other hand, when the temperature of the liquid is above the corresponding saturated vapor pressure temperature, significant evaporation occurs. This evaporation is reflected in the need for a high pump displacement. In this case, and advantageously, the pumping device may include a condenser located between the pumping chamber 16 and the pump 15A, as shown in the accompanying schematic diagram. The purpose of this condenser is to remove vapors carried by the pumping from the liquid. When the temperature of the liquid is significantly below the temperature at which the saturated vapor pressure equals the pressure maintained in the pumping chamber, evaporation is virtually zero, and a condenser is not necessary. However, to regulate the pressure, it is necessary to be able to introduce an adjustable calibration air vent upstream of the pump. All these control devices of a pumping system are familiar to those skilled in the art.

[0040] Regulating the temperature of the liquid in the storage tank relative to the saturated vapor pressure maintained in the suction chamber is also important for controlling the amount of liquid that can be carried by the strip in the processing chamber. The strip arriving from the outside is wound onto the inlet guide roller 18, then enters the interior of the storage tank 5, and exits the transition chamber by passing through the slit 14, carrying the liquid with it. Some of this liquid is removed by the squeeze rollers 17A and 17B, although when the liquid is water, they allow approximately 5 ml of liquid volume per square meter on each side to be reintroduced. If the temperature of the liquid is below the temperature at which the liquid's saturated vapor pressure equals the pressure maintained in the suction chamber, the liquid carried on the strip surface will not evaporate. It is carried into the processing chamber. On the other hand, if the temperature of the liquid is above the temperature at which the liquid's saturated vapor pressure equals the pressure maintained in the suction chamber, the liquid carried on the strip surface will evaporate. Therefore, either the liquid is maintained at a sufficiently low temperature so that there is almost no evaporation, in which case the required pumping capacity is limited even though the strip carries the liquid into the processing chamber; or the liquid is maintained at a sufficiently high temperature so that it evaporates, in which case very little liquid is carried into the interior of the processing chamber even though a higher pumping capacity is required.

[0041] When the device is used for processing liquid vapors that may permeate into the processing chamber without causing problems, it is desirable to operate it at a sufficiently low liquid temperature so that no evaporation occurs in the extraction chamber.

[0042] As described above, the installation of the transition chamber according to the invention requires sufficient clearance to accommodate the device, which has a liquid column corresponding to a relatively large pressure differential. Therefore, the apparatus according to the second embodiment described below can be implemented to eliminate the need for excessive clearance.

[0043] exist Figure 2 In the illustrated embodiment, the transition chamber separating the external atmosphere 3 from the interior 4 of the chamber used for vacuum processing of the strip 2 comprises two consecutive reservoirs 5 and 5' arranged in series. The downstream reservoir 5 is identical in all respects to the reservoirs of the aforementioned embodiments and will not be described in detail. As before, it extends from a downstream evacuation chamber 13, which communicates with the processing chamber via a slit 14 and houses the squeezing device 17. The reservoir 5' is identical to the reservoir 5 and includes an upstream inlet compartment 6' and a downstream outlet compartment 7' separated by an intermediate partition 8', which leaves a channel in the lower part of the reservoir with guide rollers 10 for the strip 2, which arrives from the outside, is wound around the guide rollers 18, and moves toward the downstream reservoir 5 to reach the processing chamber 4. The two liquid storage tanks arranged in series are connected by a vacuum chamber 20, which is connected to the downstream compartment 7' of the upstream liquid storage tank 5' on one hand and to the upstream compartment 6 of the downstream liquid storage tank 5 on the other hand.

[0044] Guide rollers 21, which allow the strip to circulate and pass through the liquid reservoir 5' to the liquid reservoir 5, are positioned in the suction chamber 20. The suction chamber 20 is connected to a suction device 22 that includes a pump 23 and an adjustable calibration leak 24.

[0045] Using this type of device, the height of the liquid column in the storage tank can be reduced by half. For example, if the pressure in the extraction chamber 13 is set to 20 hPa and the pressure in the intermediate extraction chamber 20 is set to 500 hPa, the pressure difference between atmospheric pressure and the intermediate extraction chamber 20 is 500 hPa, and the pressure difference between the intermediate extraction chamber 20 and the downstream extraction chamber 13 is also approximately 500 hPa. This corresponds to a reduction of the liquid column height by half, i.e., 5 meters when the liquid is water. Therefore, by having two storage tanks instead of just one, the height of the liquid column can be reduced by half, which significantly reduces the headroom required for equipment installation.

[0046] Those skilled in the art will understand that the required headroom can be further reduced by increasing the number of reservoirs arranged in series. In this way, a pressure drop can be distributed between two consecutive reservoirs, thereby reducing the height of the liquid column.

[0047] Furthermore, the pressure set in the intermediate extraction chamber is relatively high. Therefore, the liquid temperature is relatively high when the saturated vapor pressure equals the pressure set in the corresponding extraction chamber.

[0048] For example, if the liquid is water and the evacuation pressure in the intermediate chamber of the transition compartment, which includes two storage tanks, is set to 500 hPa, the liquid temperature at a saturated vapor pressure of 500 hPa is approximately 80°C. If a strip at ambient temperature (e.g., 20°C) is introduced into the equipment, the water in the storage tanks can be maintained at approximately 20°C. At this temperature of 20°C, the saturated vapor pressure is approximately 30 hPa, which is far below 500 hPa. Therefore, evaporation is practically zero.

[0049] Due to the lack of evaporation, the required pumping capacity in the intermediate chamber is very low once the desired pressure is reached. Because of this very low pumping capacity, a calibration leak 24 must be positioned between the pumping chamber and the pump 23 (which could be, for example, a fixed displacement pump) to regulate the pressure inside the chamber. For example, if the final intermediate pumping pressure is maintained at 550 hPa and the water temperature is approximately 20°C, there is virtually no evaporation. At a pressure of approximately 550 hPa, the calibration leak, fed by air at atmospheric pressure, operates at supersonic speeds, and the leak area is 8 mm². 2 In the case of approximately 10 m 3A flow rate of / H. Under these conditions, in order to ensure the normal operation of the unit, a pumping capacity of 10 m³ / h at a pressure of 550 hPa is required. 3 A pump with a capacity of / H is sufficient.

[0050] In the method according to the invention, when the liquid 11 in the storage tank 5 is water, the water is maintained in a temperature range of 10 to 90°C, preferably 20 to 80°C.

[0051] The liquid 11 in the storage tank 5 is preferably maintained at a pH less than or equal to 7. The pH of liquid 11 is advantageously between 3 and 5. If acidic vapors contained in the external atmosphere 3 condense on the strip 2 or upon contact with liquid 11, those skilled in the art will be able to adjust the pH of liquid 11 to neutralize any acidic vapors that may diffuse throughout the equipment. Such diffusion may occur, for example, if pickling equipment is installed on a production line upstream of the equipment to which this invention is the subject.

[0052] As described above, when the temperature of the liquid in the storage tank is low enough that they require only a low pump capacity, the aforementioned transition chambers carry the liquid into the processing chamber. To minimize or eliminate the amount of liquid they carry into the processing chamber, they must be used at a high temperature in the storage tank. This necessitates a high pump capacity.

[0053] Figure 3 The third embodiment shown can be used to enable the use of this type of device with low pump capacity and to prevent liquid from being introduced into the processing chamber.

[0054] In this embodiment, as in the first embodiment, the transition chamber includes a storage tank 5 containing liquid 11 and receives the strip 2 arriving via a downstream suction chamber 13, the same as in the aforementioned embodiment. In the downstream suction chamber 13, there is a liquid extraction device 17 including squeeze rollers, as in the previous case, and a thermal drying device 18, such as a drying device operating by induction, radiation, infrared heating, or any other device familiar to those skilled in the art. Using this type of device, the liquid 11 in the storage tank 5 can be maintained at a temperature below the temperature at which the saturated vapor pressure of the liquid is equal to the pressure in the downstream suction chamber 13, and after liquid extraction, the residual liquid carried by the strip can be heated to a temperature above the temperature at which the pressure is equal to the saturated vapor pressure of the liquid in chamber 13. In this way, the liquid remaining on the strip after squeezing is evaporated and can be absorbed by suction. The strip leaving and permeating into the processing chamber is completely dry. It should be noted that this heating of the liquid requires heating the strip itself. The surface of the strip itself must be at a temperature above the saturated vapor temperature to prevent recondensation of vapor on the strip surface.

[0055] For example, if the liquid is water, if the pressure in the downstream extraction chamber 13 is set to 100 hPa, and if the water temperature in the storage tank 5 is maintained at approximately 20°C, then the evaporation of the water contained in the storage tank is practically zero. If the water on the surface of the strip after squeezing is heated to a temperature above 46°C, the saturated vapor pressure of the residual water becomes greater than 100 hPa. As a result, the residual water evaporates, and the strip leaving the transition chamber is completely dry. Calculations that can be performed by a person skilled in the art show that such evaporation occurs in a very short time and does not require a very long strip heating length.

[0056] For example, a 1.5 m wide metal strip moving at a speed of 30 m / min in a liquid storage tank carries 27 liters / hour of water on both sides after being squeezed dry. This water volume is proportional to both the width of the strip and the moving speed.

[0057] For a pressure of approximately 100 hPa and a strip temperature above 46°C in the extraction chamber, the water evaporation rate is approximately 10.4 kg / sm. 2 The result is that the required strip length for evaporating the carried water is 0.25 mm. This means that the strip is effectively dry after reaching a temperature of 46°C. At a speed of 150 m / min, this length would be 1.25 mm.

[0058] The heat capacity required to completely dry the strip can be calculated. This heat capacity must be sufficient to heat the water, compensate for the latent heat of vaporization, and heat the strip. This capacity is proportional to the width of the strip and its moving speed, and the thicker the strip, the higher the capacity must be.

[0059] For example, for a 1.5-meter-wide steel strip that moves in a tank containing 20°C water to be introduced into a chamber with a pressure of 100 hPa and heats the residual water to 46°C, the required heat capacity is 33 kW when the thickness is 0.2 mm and the moving speed is 20 m / min; if the moving speed exceeds 120 m / min, the required heat capacity becomes 132 kW; and at a speed of 120 m / min, if the thickness is 1.5 mm, the required heat capacity becomes 504 kW.

[0060] Typically, those skilled in the art will be able to perform the necessary calculations.

[0061] Under the same assumptions, the required pump displacement is 374 m³. 3 / h. Considering the pump displacement when the pumping unit does not include a condenser, a calibration leak is not necessarily required to adjust the pressure in the pumping chamber. However, since the volumetric flow rate to be pumped varies depending on the strip's travel speed and width, it may be necessary to install a calibration leak by installing a fixed displacement pump that can be used for different strip travel speeds and strip widths.

[0062] For example, a pumping device can be used that includes a condenser positioned between the pumping chamber and a pump operating at approximately 20°C. At this temperature, the saturated vapor pressure is approximately 23 hPa, and virtually all the water carried by the pumping system is condensed, thus significantly reducing the required pumping capacity. However, it is necessary to be able to vary the pump displacement according to the strip's travel speed and its width. For this purpose, various devices familiar to those skilled in the art can be used, such as valves for adjusting the pump inlet, variable displacement pumps, or fixed displacement pumps associated with adjustable calibration leaks.

[0063] For this embodiment, as in the previous embodiments, the required headroom is a function of the liquid column height required to ensure the pressure difference between atmospheric pressure and the pressure set in the downstream extraction chamber 13. Similarly, multiple liquid storage tanks arranged in series can be used to reduce the headroom required for equipment installation. Figure 4 An embodiment of this type of transition chamber is shown, which consists of multiple liquid storage tanks arranged in series and draining into a downstream evacuation chamber including a liquid extraction device and a drying device. Since the different elements and their operating modes in this figure are the same as those in the foregoing embodiments, they will not be described in detail further.

[0064] Using the apparatus described above, in order to reduce pressure to below tens of hectopascals without extracting a very large amount of vapor, a very low liquid temperature, even below the liquid's freezing point, is required. Therefore, the apparatus described above is only suitable for implementing an inlet transition chamber within a chamber where processing is performed at pressures of tens of hectopascals (corresponding to low vacuum).

[0065] The following description relates to an embodiment of a transition chamber suitable for installation at the entrance of a vacuum processing chamber, in which processing is performed at a high vacuum (i.e., a vacuum with a pressure less than 1 Pascal, and which can be reduced to as low as 10 Pascals). -4 This example is executed under Pascal's (Pascal's) command. Figure 5 As shown in the image.

[0066] like Figure 5As shown, the transition chamber designed to bring the strip 2 from the atmospheric pressure of the outside air 3 to a pressure of less than 1 Pa in the processing chamber 4' is composed of a first low vacuum stage 30, which is identical in all respects to the low vacuum transition chamber corresponding to the third embodiment described above. Following this low vacuum stage 30 is a high vacuum stage, generally identified by 31.

[0067] As described above, the low-vacuum stage 30 includes a liquid reservoir 5, which comprises an upstream compartment 6 and a downstream compartment 7 separated by a wall 8 that provides a passage for the strip. The reservoir extends from a evacuation chamber 13 connected to the evacuation device 15 and houses a liquid extraction device 17 and a drying device 18. The evacuation chamber 13 of the low-vacuum stage discharges into the high-vacuum stage via a slit 14 formed by two rollers clamping the strip 2 between them.

[0068] The high vacuum stage 31, located downstream of the low vacuum stage 30, consists of multiple roller transition chambers arranged in series to ensure that each transition chamber performs a partial pressure drop. Each roller transition chamber is composed of pairs of pressure rollers 40, 41, and 42 arranged downstream of each other, defining volumes 43, 44, and 45 between them. The first volume 43 is defined on one hand by a pinch roller at the slit 14 located at the outlet of the low vacuum stage, and on the other hand by a first pair of pinch rollers located downstream of the high vacuum stage. Evacuation devices 43A, 44A, and 45A are provided to evacuate air into the volumes 43, 44, and 45 defined by the pairs of pinch rollers. It should be noted that the evacuation device 43, located immediately downstream of the low vacuum stage, includes a pump and a condenser. At this stage, a small amount of liquid vapor may remain and must be eliminated. The volume 44, located immediately downstream of the previous volume, includes a dry air injection 46, which enables the establishment of an overpressure that blocks any passage of liquid-carrying air from the evacuation volume 43 to the evacuation volume 44. This device allows the pressure in the downstream evacuation chamber of the low-vacuum stage to be adjusted to tens of hectopascals. In the subsequent transition chamber, the pressure can be reduced to 10 Pascals, which is possible in processing chamber 4'. -4 Pascal's pressure. Those skilled in the art will know how to implement this type of roller transition chamber.

[0069] exist Figure 6 In another embodiment shown, as in the fourth embodiment described above, the low vacuum stage 30' consists of multiple liquid storage tanks arranged in series to reduce the required headroom height of the transition chamber. Since the different elements in this embodiment are the same as their counterparts in the preceding embodiments, they will not be described in detail here.

[0070] The inlet transition chamber of the vacuum chamber in the aforementioned vacuum processing station can be used to process metal strips or strips comprising at least one polymer layer or sheet. This type of strip can be, in particular, a strip of polymer material (optionally multilayered), or a metal strip coated with one or more polymer layers.

[0071] Generally, they can be used to process strips that cannot be heated to high temperatures (e.g., the temperatures required to use liquid seals with molten metal).

[0072] These transition chambers also enable the handling of strips that have exited the process wet from upstream. With this type of transition chamber, drying the strip is not required before it enters the chamber. This is particularly true when vacuum processing is performed after wet surface preparations (e.g., degreasing or brightening), or after electroplating, or downstream of a water reservoir at the exit of a galvanizing or coating line.

[0073] Another advantage of these devices according to the invention is that they can be used to design equipment for processing high-thickness strips for which roller transfer chambers are unsuitable due to mechanical reasons or operating costs.

[0074] It should be noted that, compared with the prior art transfer chamber, the benefits of the transfer chamber according to the present invention may depend on the processing conditions under specific circumstances, as will be explained below assuming the liquid is water.

[0075] In a conventional roller-type transition chamber, most of the pumping capacity must be provided at the initial stage level. This is in contrast to chambers designed to reduce pressure from atmospheric pressure to 10... -2 In the transition chamber at 100 hPa pressure, half the pumping power is required to reduce the pressure to 100 hPa. A large volume must be pumped under still relatively high pressure, which requires a significant amount of electricity. On the other hand, in the later stages, to reduce the pressure from 100 hPa to 10... -2 At Pa, pumping is accomplished at low pressure with a relatively small volume, resulting in a significant reduction in the required power. For example, if a capacity of 5000 m³ must be installed in the initial stage... 3 A pump with a flow rate of 100 kW / h can consume up to 100 kW, while in the later stages at much lower pressures, a turbomolecular pump with a flow rate of, for example, 2000 L / s or 7200 m³ / h can be used. 3 / h capacity, and in 10 -3 It consumes only 100 watts under a pressure of Pa.

[0076] From this perspective, using a hydraulic transition chamber in the low-vacuum section has the advantage of enabling the use of much lower pumping capacity. Referring to the example above, in this type of stage, a pump with a maximum installed power of approximately 15 kW can be used, plus a water replacement pump with an installed power of approximately 5 kW for the liquid seals, and a condenser cooling pump with an installed power of 5 kW, totaling 25 kW. The heating power, as estimated above or which can be estimated in the same way for different operating conditions, must be added to this power.

[0077] The power required to bring pressure from atmospheric pressure to 100 hPa in the roller transition chamber is approximately 200 kW. The transition chamber according to the invention enables a reduction in installed power while keeping the heating power required for drying the strip less than 175 kW.

[0078] Referring to the figure above, for a steel strip 1.5 meters wide, 0.2 mm thick, and with a moving speed of 150 m / min or less, the present invention consumes less power than a roller-type transition chamber. As the thickness increases, for example, for thicknesses between 0.6 mm and 1.3 mm, the transition chamber according to the invention has an advantage for moving speeds less than 45 m / min; for even greater thicknesses between 1.3 mm and 1.4 mm, the invention has an advantage for moving speeds less than or equal to 30 m / min. These estimates are only valid for the calculation conditions considered herein.

[0079] Generally, those skilled in the art will be able to calculate operating conditions, necessary investment and operating costs, and can compare the use of a transition chamber with liquid seals with a roller transition chamber, thereby selecting the solution best suited for each situation.

[0080] Finally, it should be emphasized that the liquid used in the above description is water, although any other liquid that is liquid at room temperature and has a low saturated vapor pressure may be used.

[0081] Those skilled in the art will be able to select the most suitable liquid based on the application, and in particular on the type of strip to be treated.

Claims

1. An inlet transition chamber for a vacuum chamber (4, 4') of a vacuum processing apparatus for moving strip (2), the transition chamber being of the type comprising at least one liquid reservoir (5) containing liquid, the liquid reservoir (5) comprising an upstream compartment (6) and a downstream compartment (7) separated by a vertical partition (8) that creates an unobstructed channel (9) between the two compartments at the lower part of the liquid reservoir, the channel (9) having guide rollers (10) for guiding the strip, characterized in that, The inlet transition chamber includes a downstream extraction chamber (13) extending from the downstream compartment (7) and connected to the extraction device (15), wherein the downstream extraction chamber (13) has a liquid extraction device (17), wherein the downstream extraction chamber (13) includes an outlet slit (14) for the strip, and wherein the transition chamber includes a device (12) for cooling the liquid contained in the liquid reservoir.

2. The entrance transition chamber according to claim 1, characterized in that, The inlet transition chamber includes multiple liquid storage tanks (5, 5') arranged in series. The upstream compartment (6) and the downstream compartment (7') of two adjacent liquid storage tanks (5, 5') are connected at their upper parts by an intermediate evacuation chamber (20), which has guide rollers (21) for metal strips and is connected to an evacuation device (22).

3. The entrance transition chamber according to claim 2, characterized in that, The air extraction device (22) of the intermediate air extraction chamber (20) includes a pump (23) and an adjustable calibration leak (24).

4. The entrance transition chamber according to claim 2 or claim 3, characterized in that, At least two liquid storage tanks (5, 5') include devices (12, 12') for cooling the liquid.

5. The entrance transition cabin according to any one of claims 1 to 4, characterized in that, The outlet slit (14) of the downstream extraction chamber (13) includes a roller seal consisting of two rollers (14A, 14B) adapted to clamp the moving strip (2).

6. The entrance transition cabin according to any one of claims 1 to 5, characterized in that, The extraction device (15) connected to the downstream extraction chamber (13) includes a condenser (16).

7. The entrance transition cabin according to any one of claims 1 to 6, characterized in that, The pumping device (15) connected to the downstream pumping chamber (13) includes a device for adjusting the pump discharge rate.

8. The entrance transition cabin according to any one of claims 1 to 7, characterized in that, The liquid extraction device (17) includes at least two pinch rollers (17A, 17B).

9. The entrance transition chamber according to claim 8, characterized in that, The inlet transition chamber also includes a thermal drying device (18) located downstream of the liquid extraction device (17) relative to the direction of movement of the strip.

10. The entrance transition chamber according to claim 9, characterized in that, The inlet transition chamber includes at least one roller transition chamber downstream of the downstream extraction chamber (13).

11. The entrance transition chamber according to claim 10, characterized in that, At least one roller transition chamber located downstream of the downstream extraction chamber includes a dry gas injection (46).

12. The entrance transition cabin according to any one of claims 1 to 11, characterized in that, The liquid (11) is water.

13. A method for ensuring a seal at the entrance of a vacuum processing chamber for a continuously moving strip (2), comprising an entrance transition chamber according to any one of claims 1 to 12, characterized in that, The downstream evacuation chamber (13) is evacuated to maintain a pressure below atmospheric pressure, and the fluid (11) contained in the downstream storage tank (5) is maintained at a temperature below the temperature at which the saturated vapor pressure of the fluid is equal to the pressure maintained in the downstream evacuation chamber (13).

14. The method according to claim 13, characterized in that, When the inlet transition chamber includes a heat drying device (18), after the liquid is extracted, the liquid remaining on the surface of the strip (2) is heated to a temperature higher than the condensation temperature of the liquid under the pressure maintained in the downstream extraction chamber (13).

15. The method according to claim 13 or claim 14, characterized in that, The strip (2) is a metal strip.

16. The method according to claim 13 or claim 14, characterized in that, The strip (2) is composed of at least one polymer film.

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