Sealing air brake for deposition chamber

Abstract

The invention relates to a sealing lock (5) for a vacuum deposition installation for coating on a running metal strip along a running path (P), the sealing lock (5) comprising a wall (6) and at least three pairs of rollers located inside the wall (6) wherein-each of the at least three pairs of rollers-comprises a roller (7) having a metal surface and a roller (8) having an elastomeric surface layer (9), the elastomeric surface layer (9) has a thickness of 3 mm to 30 mm, each of said at least three pairs of rollers forming a gap of 1 mm to 11 mm,-the rollers with elastomeric surface layers of two consecutive pairs of rollers are located on opposite sides of said running path (P).

Description

Technical Field

[0001] The present invention relates to a sealed airlock for a deposition chamber under vacuum. The sealed airlock is advantageously used as an exit airlock in a vacuum deposition facility. Background Art

[0002] In the field of metallurgy, the use of vapor deposition is becoming more and more attractive. In fact, vapor deposition allows a wider range of products to be realized, especially in terms of coating compositions. In addition, from an environmental point of view, vapor deposition produces less waste of the material to be coated.

[0003] After undergoing thermal and mechanical treatments, the strips can be transported to a vapor deposition facility. -5 The deposition process is usually carried out in a vacuum chamber with pressures in the order of millibars or lower. Using such low pressures requires isolating the deposition chamber from the atmosphere of the rest of the production line. Hermetic locks have been developed to solve this problem.

[0004] For example, as in Figure 1 , EP 1 627 096 describes a sealing airlock 1 comprising several pairs of rollers. Each pair of rollers comprises a rubber-coated roller 2 and a roller with a metal surface 3. Two consecutive pairs of rollers define a subchamber 4 maintained at a pressure below atmospheric pressure. The airtightness of each subchamber is ensured by prestressing the rubber-coated roller against the roller with a metal surface.

[0005] Unfortunately, this seal lock can lead to quality defects. In addition, due to the mechanical properties and heat resistance of the elastomeric roller, the elastomeric roller is limited in terms of strip specifications and line speeds. Summary of the invention

[0006] The present invention aims to provide a sealing lock for a deposition chamber under vacuum, which overcomes the disadvantages of the prior art. In particular, it aims to provide a sealing lock that reduces the degradation of the coating of the metal strip in operation due to the sealing airlock.

[0007] like Figure 2 As shown in the figure, the present invention relates to a sealing lock (5) of a vacuum deposition facility for coating a metal strip in motion along a running path (P), the sealing lock (5) comprising a wall (6) and at least three pairs of rollers located inside the wall (6), wherein:

[0008] - Each pair of rollers of the at least three pairs of rollers

[0009] - comprising a roller (7) with a metal surface and a roller (8) with an elastomeric surface layer (9) having a thickness of 3 to 30 mm, each of the at least three pairs of rollers forming a gap of 1 to 11 mm,

[0010] - The rollers with an elastomeric surface layer of the two pairs of continuous rollers are located on opposite sides of said running path (P). BRIEF DESCRIPTION OF THE DRAWINGS

[0011] As mentioned above Figure 1 A longitudinal view of a sealing lock for vacuum deposition in a vacuum according to the prior art is shown.

[0012] Figure 2 A longitudinal view of an embodiment of a sealing lock for a vacuum deposition facility according to the invention is shown.

[0013] Figure 3 A longitudinal view of an embodiment of a sealing lock for a vacuum deposition facility according to the invention is shown.

[0014] Figure 4 A longitudinal view of a second embodiment of a sealing lock for a vacuum deposition facility according to the invention is shown.

[0015] Figure 5 A longitudinal view of an embodiment of a deposition method according to the invention is illustrated. DETAILED DESCRIPTION

[0016] The inventors have unexpectedly observed that an uneven strip passing through a pair of squeeze rollers, as known in the prior art, may cause degradation of the metal coating. Apparently, this degradation occurs because the friction varies along the width of the strip.

[0017] This drawback is prevented by the present invention. A gap greater than the thickness of the strip avoids continuous squeezing of the strip and therefore avoids the creation of friction differences along the width of the strip as it passes between a pair of rollers. This gap, combined with the elastomeric surface on the rollers, allows the unevenness of the strip to be managed. In fact, in the event that the strip is uneven due to flatness defects, the strip will briefly contact the rollers, but the coating of the running metal strip will not be degraded due to the elastomeric layer.

[0018] Therefore, the combination of a gap greater than the thickness of the strip and the presence of a roller with an elastomeric surface has a synergistic effect on the maintenance of the coating quality. Since the coated running metal strip is not squeezed by the pair of rollers, the friction variations along the width of the strip are eliminated and the coating of the running metal strip is therefore preserved. In fact, it suppresses the constant compression experienced by the elastomeric layer applied by the strip, which also increases the life of the elastomeric layer. In addition, it allows processing thicker strips and / or processing at higher speeds. Moreover, since the running metal strip is in contact with the roller with a metal surface, but not continuously with the roller with an elastomeric surface, it allows the running metal strip to be brought into contact with the roller with an elastomeric layer without damaging the coating of the strip in the event of vibrations or thickness variations of the strip.

[0019] like Figure 2 As illustrated in , the walls 6 of the sealing lock define a sealing lock chamber 10. The walls of the sealing lock 5 may be defined as lateral walls, an upper wall and a lower wall.

[0020] Each roller can be positioned in a bracket 11 fastened to the lower or upper wall facing the roller. This arrangement allows minimizing leakage. Preferably, the lower and upper walls are removable covers.

[0021] The roller support 12 can be disassembled and fastened to the upper and lower walls (eg covers).The roller support 12 allows ensuring maintenance of the chamber and easy access to the rollers.

[0022] Furthermore, the roller is held on the side of the cover facing the roller in the bracket.This arrangement allows leakage to be minimized.

[0023] The sealing lock 5 comprises at least three pairs of rollers. Preferably, the sealing lock comprises at least five pairs of rollers. Preferably, the sealing lock comprises at most nine pairs of rollers. Figure 2 In the embodiment shown, the chamber includes six pairs of rollers between which the metal strip can pass.

[0024] The width of the rollers is at least as wide as the width of the metal being run.

[0025] A pair of rollers comprises a roller 7 with a metal surface and a roller 8 with an elastomer surface layer. The roller with an elastomer surface layer is a roller having an elastomer layer 9 with a thickness of 3 mm to 30 mm on its periphery. This range of elastomer layer thickness is advantageous. In fact, an elastomer layer thickness of at least 3 mm allows to obtain a life sufficient for industrial purposes. An elastomer layer thickness of a maximum of 30 mm allows to keep the elastomer layer sufficiently cooled. In fact, if the elastomer layer thickness is greater than 30 mm, it becomes too difficult to remove heat through the roller.

[0026] Preferably, the roller having a metal surface has a steel surface.

[0027] Preferably, the elastomeric layer is 5mm to 15mm thick. Even more preferably, the elastomeric layer is 5mm to 10mm thick.

[0028] Preferably, the elastomer layer is made of a vulcanized elastomer. Even more preferably, the elastomer is made of a fluorocarbon rubber as defined by ASTM International Standard D1418 in the "FKM" category. Even more preferably, the elastomer is made of a hydrogenated acrylonitrile butadiene as defined by ASTM International Standard D1418 in the "HNBR" category.

[0029] A pair of rollers defines a gap between the two rollers. Preferably, the pair of rollers is configured so that the gap between the two rollers can be 1 mm to 11 mm. The pair of rollers allows a gap of 0.8 mm to 3 mm between the rollers having an elastomeric surface and a running metal strip having a thickness of 0.2 mm to 8 mm.

[0030] Even more preferably, the pair of rollers is configured so that the gap between the two rollers can be 1 mm to 5 mm. This is particularly advantageous for thin strips with a thickness of up to 4 mm.

[0031] Advantageously, the roller with an elastomeric surface layer comprises a cooling system capable of cooling the elastomeric surface layer. Preferably, the cooling system comprises a collar through which a coolant passes. Preferably, the elastomeric surface layer contacts the collar.

[0032] The pairs of rollers are arranged so that the rollers with elastomeric surfaces in two pairs of continuous rollers are located on opposite sides of the travel path. Figure 2 As illustrated, the first, third, and fifth rollers (from left to right) on the upper side of the running path have metal surfaces, while the second, fourth, and sixth rollers have elastomeric surfaces.

[0033] The pair of rollers is arranged so that two consecutive metal rollers, the strip S (eg, the running path of the strip) and the wall of the sealing lock define a subchamber 13. The subchamber 13 is Figure 3 Each of the subchambers is connected to at least a pumping system. Figure 2 As shown, the direction of the travel path changes at each metal roller.

[0034] Preferably, the subchamber is defined by two consecutive metal rollers, said running path (P) and the walls of said sealing lock.

[0035] Thus, the arrangement of the elastomer roller and the roller with a metal surface allows to define as in Figure 3In fact, if all rollers with metal surfaces in contact with the running metal strip were located on the same side of the running metal strip, it would not allow the sub-chambers to be defined and therefore the airlock to be formed.

[0036] In operation, the pressure of successive subchambers decreases towards the deposition chamber, for example from the inlet to the outlet for an inlet containment lock. In the case of an outlet lock, the opposite occurs.

[0037] Preferably, the pressure of the at least one sub-chamber decreases towards the deposition chamber.

[0038] The pressure of successive subchambers is managed by a pumping system. Such pumping systems are well known to those skilled in the art. For example, the pumping system can work in cascade from the subchamber closest to the deposition chamber toward the opposite subchamber. The pumping system allows for handling pressure differences between subchambers. The pumping system can include several types of pumps, such as liquid ring pumps, roots pumps and turbomolecular pumps.

[0039] Optionally, the sealing lock comprises at least one additional pair of rollers, said at least one additional pair of rollers comprising two rollers having an elastomeric surface and positioned at the outlet of said sealing lock, said lock forming a gap of 2 mm to 8 mm. Even more preferably, said at least one pair of rollers closest to the outlet of said sealing lock defines a gap capable of squeezing said running metal strip passing between said at least one pair of rollers. This embodiment is shown in Figure 4 As illustrated, the sixth pair of rollers includes two rollers having an elastomeric surface.

[0040] Surprisingly, it was found that coating quality issues are not only due to roller squeezing of the strip, but also depend on strip temperature (e.g., deposited coating temperature). After coating, the strip temperature in the sealing lock decreases, which allows the use of a pair of squeezing rollers on the exit side of the sealing lock.

[0041] The invention also relates to a vacuum deposition facility comprising a vacuum deposition chamber 15 connected to an inlet sealing lock 51 or an outlet sealing lock 52 as described above.

[0042] Preferably, the vacuum deposition facility comprises a vacuum deposition chamber connected to an entry sealing lock and an exit sealing lock as described above.

[0043] Preferably, the vacuum deposition facility is capable of coating a running metal substrate by propelling at least one metal vapor at supersonic speed towards the running strip.

[0044] As in Figure 3The invention also relates to a method for continuously depositing a coating from at least one metal on a running metal strip inside a vacuum deposition facility according to claim 7, the vacuum deposition facility comprising an outlet sealing lock (52), the method comprising the following consecutive steps:

[0045] - depositing at least one metal coating on said running strip in said vacuum deposition chamber, and

[0046] - passing the running strip through the outlet sealing lock (52) so that the running metal strip contacts the metal roller when the strip passes between a pair of rollers comprising a metal roller and an elastomeric roller, and the gap between two rollers of the pair of rollers is 0.8 mm to 3 mm larger than the thickness of the running strip.

[0047] like Figure 3 As shown in the figure, the running metal strip is from one side ( Figure 3 ) to the left side of the seal lock, and from the other side ( Figure 3 The other side is preferably the opposite side in the sense that the strip path is substantially straight.

[0048] In a first step, a coating of at least one metal is deposited on at least one side of a running metal strip in a vacuum deposition chamber.

[0049] Preferably, said metal coating deposition is accomplished by propelling at least one metal vapor towards said running strip at supersonic speed.

[0050] In the second step, the running metal strip passes through the sealing lock. Figure 3 As shown in the figure, the strip runs between each pair of rollers. The strip contacts each of the metal rollers and is squeezed by each of the metal rollers, thereby forming a seal between the metal surface of the roller and the strip. The running path of the strip is deflected by each of the metal rollers. A gap of 0.8 mm to 3 mm is formed between the running metal strip and the roller with the elastomer layer, so that the running metal strip is not continuously squeezed by the pair of rollers including the roller with the metal surface and the roller with the elastomer layer. However, since the strip sometimes has flatness defects, the gap may temporarily become smaller, and the strip may even briefly contact the elastomer layer.

[0051] Preferably, a pair of rollers with an elastomer surface layer and a metal surface layer are rotated. This rotation avoids local overheating due to radiation from the running metal strip and helps to extend the life of the rollers.

[0052] Even more preferably, in a pair of rollers, the roller with the elastomeric surface layer rotates in the opposite direction to the roller with the metal surface. This direction of rotation reduces coating degradation. For example, in Figure 3 , the movement direction D of the strip is from left to right, and the rotation direction of the rollers with the elastomer surface layer in the first pair, the third pair and the fifth pair of rollers is clockwise, while the rotation direction of the rollers with the metal surface is counterclockwise.

[0053] Preferably, when a sealing lock is used comprising at least one pair of additional rollers, the at least one pair of additional rollers comprising two rollers having an elastomeric surface and positioned at the outlet of the sealing lock, the strip is squeezed between the pair of additional elastomeric rollers, the pair of additional elastomeric rollers having a gap between the elastomeric rollers.

[0054] The running strip has a thickness of typically 0.2 mm to 8 mm. However, sometimes the strip has flatness defects.

[0055] Preferably, the running strip has a thickness of 0.2 mm to 4 mm.

Claims

1. A sealing lock (5) of a vacuum deposition facility for coating a metal strip in motion along a running path (P), the sealing lock (5) comprising a wall (6) and at least three pairs of rollers located inside the wall (6), wherein: - Each pair of rollers of the at least three pairs of rollers - comprising a roller (7) with a metal surface and a roller (8) with an elastomeric surface layer (9), the elastomeric surface layer (9) having a thickness of 3 mm to 30 mm, each of the at least three pairs of rollers forming a gap of 1 mm to 11 mm, - The rollers with an elastomeric surface layer of the two pairs of continuous rollers are located on opposite sides of said running path (P).

2. The sealing lock according to claim 1, comprising at least five pairs of rollers.

3. The sealing lock according to claim 1 or 2, wherein: The elastomer surface layer (9) is 5 mm to 15 mm thick.

4. The sealing lock according to any one of claims 1 to 3, comprising at least one pair of additional rollers, the at least one pair of additional rollers comprising two rollers having an elastomeric surface and positioned at the outlet of the sealing lock, the rollers forming a gap of 0.2 mm to 8 mm.

5. The sealing lock according to any one of claims 1 to 4, wherein: The subchambers are defined by two consecutive metal rollers, the running path (P) and the walls of the sealing lock.

6. A vacuum deposition facility comprising a vacuum deposition chamber (15) connected to an inlet sealing lock (51) and / or an outlet sealing lock (52) according to any one of claims 1 to 6.

7. A method for continuously depositing a coating from at least one metal on a running metal strip inside a vacuum deposition facility according to claim 6, the vacuum deposition facility comprising an exit sealing lock (52), the method comprising the following consecutive steps: - depositing at least one metal coating on said running strip in said vacuum deposition chamber, and - passing the running strip through the outlet sealing lock (52) so that the running metal strip contacts the metal roller when the strip passes between a pair of rollers comprising a metal roller and an elastomeric roller, and a gap between two rollers of the pair of rollers is 0.8 mm to 3 mm larger than the thickness of the running strip.

8. The method according to claim 7, wherein: The metal coating deposition is accomplished by propelling at least one metal vapor at supersonic speeds toward the running strip.

9. The method according to claim 8 or 9, wherein: The outlet sealing lock (52) is according to claim 4, and the strip is squeezed between the additional pair of elastomeric rollers.

10. The method according to any one of claims 7 to 9, wherein: The pressure of the at least one sub-chamber decreases toward the deposition chamber.

11. The method according to any one of claims 7 to 10, wherein: A pair of rollers having an elastomeric surface layer and a metal surface layer are rotated.

12. The method according to claim 11, wherein: The direction of rotation of the roller with the elastomeric surface layer is opposite to the direction of rotation of the roller with the metal surface.

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