Sealing airlock for deposition chamber

Abstract

The present invention relates to a sealing lock (5) for an installation for vacuum-depositing a coating on a traveling metal strip advancing on a travel path (P), comprising a wall (6) and at least three pairs of rolls inside the wall (6), each pair of rolls of the at least three pairs of rolls comprising a roll (7) with a metal surface and a roll (8) with an elastomeric surface layer (9) having a thickness of 3 to 30 mm, forming a gap of 1 to 11 mm, and the rolls with the elastomeric surface layer of two consecutive pairs of rolls are located on opposite sides of the travel path (P).

Description

[Technical Field]

[0001] The present invention relates to a sealing airlock for a deposition chamber under vacuum, which is advantageously used as an exit airlock in a vacuum deposition installation. [Background technology]

[0002] In metallurgy, the use of vapor deposition is becoming increasingly attractive. Indeed, vapor deposition makes it possible to realize a wider range of products, especially in terms of coating compositions. Furthermore, from an environmental point of view, vapor deposition results in less waste of the coated material.

[0003] After undergoing heat and mechanical treatment, the strip can be transported to a deposition facility. -5 This is done in a vacuum chamber with a pressure on the order of millibars or less. The use of such low pressures requires atmospheric isolation of the deposition chamber from the rest of the production line. To solve this problem, sealing locks have been developed.

[0004] For example, as shown in Figure 1, EP 1,627,096 describes a sealing airlock 1 comprising several pairs of rolls. Each pair of rolls comprises a rubber-coated roll 2 and a metal-surfaced roll 3. Two consecutive pairs of rolls define subchambers 4, which are kept at a pressure lower than atmospheric pressure. The airtightness of each subchamber is ensured by pre-pressing the rubber-coated roll against the metal-surfaced roll.

[0005] Unfortunately, such sealing locks lead to the appearance of quality defects. Furthermore, the mechanical and thermal resistance of the elastomeric roll limits strip gauge and line speed.

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

[0007] As shown in FIG. 2, the present invention relates to a sealing lock (5) for an installation for vacuum-depositing a coating on a traveling metal strip advancing along a travel path (P), comprising a wall (6) and at least three pairs of rolls inside the wall (6), each pair of rolls of the at least three pairs of rolls comprising a roll (7) with a metal surface and a roll (8) with an elastomeric surface layer (9) having a thickness of 3 to 30 mm, forming a gap of 1 to 11 mm, and the rolls with the elastomeric surface layer of two consecutive pairs of rolls are located on opposite sides of the travel path (P). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent No. 1627096 [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1, already mentioned above, shows a longitudinal section of a sealing lock for vacuum deposition in a vacuum according to the prior art. [Figure 2] FIG. 2 shows a longitudinal section of an embodiment of a sealing lock for a vacuum deposition installation according to the invention. [Figure 3] FIG. 3 shows a longitudinal section of one embodiment of a sealing lock for a vacuum deposition installation according to the invention. [Figure 4] FIG. 4 shows a longitudinal section of a second embodiment of a sealing lock for a vacuum deposition installation according to the invention. [Figure 5] FIG. 5 illustrates a longitudinal cross-sectional view of one embodiment of a deposition method according to the present invention. Summary of the Invention [Problem to be solved by the invention]

[0010] Surprisingly, it has been observed by the present inventors that an uneven strip passing through a pair of pinching rolls, as is known in the prior art, can result in degradation of the metal coating. Apparently, such degradation occurs because friction varies along the width of the strip. [Means for solving the problem]

[0011] The present invention avoids this drawback. A gap larger than the strip thickness avoids constant pinching of the strip and therefore avoids differential friction along the strip width as it passes between the pair of rolls. This gap, combined with the elastomeric surface on the rolls, makes it possible to manage unevenness in the strip. Indeed, if the strip is not flat due to a lack of flatness, it will briefly come into contact with the rolls, but the coating of the running metal strip will not be deteriorated thanks to the elastomeric layer.

[0012] As a result, the combination of a gap larger than the strip thickness and the presence of rolls with elastomeric surfaces has a synergistic effect on maintaining coating quality. Because the coated, traveling metal strip is not sandwiched between the roll pairs, frictional variations along the strip width are eliminated, thus maintaining the coating on the traveling metal strip. In fact, not sandwiching the metal strip between the roll pairs reduces the constant compression experienced by the elastomer layer caused by the strip, thereby extending the life of the elastomer layer. Furthermore, not sandwiching the metal strip between the roll pairs allows for thicker strips to be processed and / or at higher speeds. Furthermore, because the traveling metal strip is in contact with the rolls with metal surfaces but not continuously with the rolls with elastomeric surfaces, it is possible for the traveling metal strip to come into contact with the rolls with elastomeric layers in the event of strip vibration or thickness fluctuations without damaging the coating on the strip. DETAILED DESCRIPTION OF THE INVENTION

[0013] As shown in Figure 2, the walls 6 of the sealing lock define a sealing lock chamber 10. The walls of the sealing lock 5 may be defined as side, upper and lower walls.

[0014] Each roll can be placed in a cradle 11 fixed to the lower or upper wall facing the roll. This arrangement makes it possible to minimize leakage. Preferably, the lower and upper walls have removable covers.

[0015] The roll bearings 12 are removable and are fixed to the upper and lower walls (e.g., covers). The ability to remove the roll bearings 12 allows for easy access to the chamber for maintenance and to the rolls.

[0016] Furthermore, the roll is held in the cradle with the side of the cover facing the roll, an arrangement that makes it possible to minimize leakage.

[0017] The sealing lock 5 comprises at least three pairs of rolls. Preferably, the sealing lock comprises at least five pairs of rolls. Preferably, the sealing lock comprises a maximum of nine pairs of rolls. In the embodiment shown in Figure 2, the chamber comprises six pairs of rolls between which the metal strip can pass.

[0018] The roll is at least as wide as the width of the metal being run.

[0019] The pair of rolls includes a roll 7 with a metal surface and a roll 8 with an elastomer surface layer. The elastomer surface roll has an elastomer layer 9 with a thickness of 3 to 30 mm around its periphery. This thickness range of the elastomer layer is advantageous. In fact, an elastomer layer thickness of at least 3 mm ensures a sufficient life for industrial purposes. A maximum thickness of 30 mm ensures that the elastomer layer can be kept sufficiently cooled. In fact, if the elastomer layer thickness exceeds 30 mm, heat removal by the roll becomes very difficult.

[0020] Preferably, the metal surfaced rolls have steel surfaces.

[0021] Preferably, the elastomer layer has a thickness of 5 to 15 mm, and even more preferably, the elastomer layer has a thickness of 5 to 10 mm.

[0022] Preferably, the elastomeric layer is made of a vulcanized elastomer. Even more preferably, the elastomer is made of fluorocarbon rubber as defined in ASTM International Standard D1418 under the "FKM" category. Even more preferably, the elastomer is made of Hydrogenated Acrylonitrile Butadiene as defined in ASTM International Standard D1418 under the "HNBR" category.

[0023] The pair of rolls defines a gap between the two rolls. Preferably, the pair of rolls is configured so that the gap between the two rolls can be 1 to 11 mm. By configuring the gap between the two rolls so that the gap can be 1 to 11 mm, it is possible to have a gap of 0.8 to 3 mm between the roll having the elastomer surface and the running metal strip having a thickness of 0.2 to 8 mm.

[0024] More preferably, the pair of rolls is configured such that the gap between the two rolls can be 1 to 5 mm, which is particularly advantageous for thin strips having a thickness of up to 4 mm.

[0025] Advantageously, said roll with an elastomeric surface layer is equipped with a cooling system capable of cooling said elastomeric surface layer, said cooling system preferably comprising a ferrule through which a coolant passes, said elastomeric surface layer preferably being in contact with said ferrule.

[0026] The roll pairs are arranged so that the rolls with elastomeric surfaces of two consecutive roll pairs are on opposite sides of the travel path. For example, as shown in Figure 2, the first, third, and fifth rolls on the upper side of the travel path (from left to right) have metal surfaces, while the second, fourth, and sixth rolls have elastomeric surfaces.

[0027] The roll pairs are arranged such that the two consecutive metal rolls, the strip S (e.g., the running path of the strip) and the walls of the sealing lock define subchambers 13. The subchambers 13 are represented by hashed areas in FIG. 3. Each subchamber is connected to at least a pump system. As shown in FIG. 2, the direction of the running path is changed for each metal roll.

[0028] Preferably, the sub-chamber is defined by two successive metal rolls, the walls of said travel path (P) and said sealing lock.

[0029] As a result, the arrangement of elastomeric rolls and rolls with metal surfaces makes it possible to define subchambers as shown in Figure 3. Indeed, if the rolls with metal surfaces that the running metal strip contacts are all on the same side of the running metal strip, it is not possible to define subchambers and therefore to create an airlock.

[0030] During operation, the pressure in successive subchambers decreases towards the deposition chamber, for example from the inlet to the outlet due to an inlet sealing lock, whereas the opposite situation occurs in the case of an outlet lock.

[0031] Preferably, the pressure in the at least one sub-chamber decreases towards the deposition chamber.

[0032] The pressures of the successive subchambers are managed by a pumping system. Such pumping systems are well known to those skilled in the art. For example, the pumping system can operate in a cascade fashion, starting from the subchamber closest to the deposition chamber to the subchamber on the opposite side. This allows for pressure differences between the subchambers to be addressed. The pumping system can include several types of pumps, such as a liquid ring pump, a roots pump, and a turbomolecular pump.

[0033] Optionally, the sealing lock comprises two rolls with elastomeric surfaces and at least one additional pair of rolls located at the exit of the sealing lock, the locks forming a gap of 2 to 8 mm. Even more preferably, the at least one pair of rolls closest to the exit of the sealing lock defines a gap capable of pinching the running metal strip passing between them. Such an embodiment is illustrated in Figure 4, where a sixth pair of rolls comprises two rolls with elastomeric surfaces.

[0034] Surprisingly, it was found that the coating quality problem is not only due to pinching of the strip by the rolls, but also depends on the strip temperature (e.g., the temperature of the deposited coating). After being coated, the strip temperature drops within the sealing lock, which makes it possible to use a pinching roll pair on the exit side of the sealing lock.

[0035] The invention also relates to a vacuum deposition installation comprising a vacuum deposition chamber 15 connected to one entrance sealing lock 51 or one exit sealing lock 52 as previously described.

[0036] Preferably, the vacuum deposition equipment comprises a vacuum deposition chamber connected to one entrance sealing lock and one exit sealing lock, as described above.

[0037] Preferably, the vacuum deposition facility is capable of coating a moving metal substrate by ejecting at least one metal vapor at supersonic speed towards the moving strip.

[0038] The present invention relates to a method for continuously depositing a coating on a running metal strip from at least one metal in a vacuum deposition installation according to claim 7, which is equipped with an exit sealing lock (52), as shown in FIG. 3, comprising: - depositing at least one metal coating onto the traveling strip in the vacuum deposition chamber; and - passing the running strip through the exit sealing lock (52) so that when the strip passes between a pair of rolls comprising a metal roll and an elastomer roll, the running metal strip comes into contact with the metal roll and the gap between the pair of rolls is 0.8 to 3 mm larger than the thickness of the running strip; The present invention also relates to a method comprising the steps of:

[0039] As illustrated in Figure 3, the traveling metal strip enters the sealing lock from one side (left side in Figure 3) and exits the sealing lock from the other side (right side in Figure 3), preferably the opposite side in the sense that the strip path is essentially straight.

[0040] In a first step, at least one metallic coating layer is deposited on at least one side of a running metal strip in a vacuum deposition chamber.

[0041] Preferably, said metal coating deposition is performed by ejecting at least one metal vapor at supersonic speed towards said running strip.

[0042] In the second step, the traveling metal strip passes through a sealing lock. As shown in Figure 3, the strip travels between each pair of rolls. The strip contacts each of the metal rolls and is pressed by each of the metal rolls to form a seal between the strip and the metal surface of the roll. The traveling path of the strip is bent by each of the metal rolls. To prevent the traveling metal strip from being continuously sandwiched between a pair of rolls, one with a metal surface and the other with an elastomeric layer, a gap of 0.8 to 3 mm is formed between the traveling metal strip and the roll with the elastomeric layer. However, because the strip occasionally lacks flatness, the gap may momentarily become smaller, and the strip may even briefly come into contact with the elastomeric layer.

[0043] Preferably, the roll having the metal surface and the roll having the elastomeric surface layer paired therewith are rotated, which helps to avoid local overheating due to heat radiation from the traveling metal strip and to extend the life of the rolls.

[0044] Even more preferably, in a pair of rolls, the direction of rotation of the roll with the elastomeric surface layer is opposite to the direction of rotation of the roll with the metal surface. Such a direction of rotation reduces degradation of the coating. For example, in Figure 3, the direction of movement of strip D is from left to right, and the direction of rotation of the roll with the elastomeric surface layer of the first, third, and fifth roll pairs is clockwise, while the direction of rotation of the roll with the metal surface is counterclockwise.

[0045] Preferably, when using a sealing lock comprising two rolls with an elastomeric surface and at least one further pair of rolls located at the outlet of the sealing lock, the strip is sandwiched between the further pair of elastomeric rolls with a gap between the elastomeric rolls.

[0046] The running strip generally has a thickness of 0.2 to 8 mm, however, sometimes the strip has a lack of flatness.

[0047] Preferably, the running strip has a thickness of 0.2 to 4 mm.

Claims

1. A sealing lock (5) for an installation for vacuum-depositing a coating on a traveling metal strip advancing along a travel path (P), comprising a wall (6) and at least three pairs of rolls inside said wall (6), Each pair of rolls of the at least three pairs of rolls A roll (7) having a metal surface and a roll (8) having an elastomer surface layer (9) having a thickness of 3 to 30 mm, forming a gap of 1 to 11 mm; two successive pairs of rolls with elastomeric surface layers are on opposite sides of said travel path (P); Sealing lock (5).

2. 10. The sealing lock of claim 1, comprising at least five pairs of rolls.

3. A sealing lock according to claim 1 or 2, wherein said elastomeric surface layer (9) is 5 to 15 mm thick.

4. 4. The sealing lock according to claim 1, comprising two rolls with an elastomeric surface and at least one further pair of rolls located at the outlet of the sealing lock, said rolls forming a gap of 0.2 to 8 mm.

5. A sealing lock according to any one of claims 1 to 4, wherein a sub-chamber is defined by two successive metal rolls, said travel path (P) and the walls of said sealing lock.

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

7. 7. A method for continuously depositing a coating on a running metal strip from at least one metal in a vacuum deposition installation according to claim 6, comprising an exit sealing lock (52), depositing at least one metal coating onto the traveling strip in the vacuum deposition chamber; and passing the running strip through the exit sealing lock (52) so that when the strip passes between a pair of rolls comprising a metal roll and an elastomer roll, the running metal strip comes into contact with the metal roll and the gap between the two rolls of the pair is 0.8 to 3 mm greater than the thickness of the running strip; The method includes the step of continuously

8. 8. The method of claim 7, wherein said metal coating deposition is performed by ejecting at least one metal vapor at supersonic speed toward said traveling strip.

9. 10. The method according to claim 8 or 9, wherein the exit sealing lock (52) is as described in claim 4, and the strip is sandwiched between the further pair of elastomeric rolls.

10. The method of any one of claims 7 to 9, wherein the pressure in the at least one subchamber decreases towards the deposition chamber.

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

12. 12. The method of claim 11, wherein the direction of rotation of the roll having the elastomeric surface layer is opposite to the direction of rotation of the roll having the metal surface.

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