Patent Application
20150203314
The present disclosure relates to a continuous reel-to-reel arrangement for transportation of continuous substrate materials from an unwinding material reel to a winding material reel, a system comprising at least two such arrangements, a method of feeding substrate materials to at least one treatment zone and a method of treating substrate materials.
In continuous reel-to-reel apparatuses an elongated substrate is transported from one reel or roll to another. Such apparatuses may be used in various areas, for example for paper processing and label printing. Reel-to-reel apparatuses are also used for application of coatings or thin films on continuous flexible substrates and may for example be used in the production of photovoltaic cells, for coating of various components for the electronic industry, and for the purpose of decoration.
Different coating methods, such as electroplating, CVD (Chemical Vapour Deposition) or PVD (Physical Vapour Deposition) may be used in such reel-to-reel coating apparatuses.
For all applications mentioned above a reliable coating apparatus is essential in which reproducible coating layers of high quality may be produced on continuous substrates. It is also of importance to avoid scratching or damaging of the coated surface when the substrate is transported through the reel-to-reel apparatus and during winding of the coated substrate material on the material reel.
In U.S. Pat. No. 4,763,601 a continuous coating apparatus for coating of a continuous strip, such as a metal or a plastic strip, is disclosed. Coating is only applied on one side of the strip and the coated surface does not come into contact with guide rollers of the apparatus. Hence, the risk of the coated surface being scratched is low. The apparatus in this disclosure comprises a pair of strip supply/take-up devices capable of uncoiling the strip, supplying the strip in a tensed condition to at least two coating zones, and taking up and coiling the strip. The at least two coating zones are at least two of an ion plating coating zone, a sputtering coating zone and a plasma CVD coating zone arranged in series in the direction of run of a strip between said strip supply/take-up devices. Between adjacent coating zones and between a supply/take-up device and an adjacent coating zone are partition walls with slits adapted to allow the strip to pass through and to maintain a vacuum in the coating zones. The partition wall has a pair of guide rollers located in the vicinity of an upper edge of the slit so as to tense the strip such that the path of the strip is slightly convex downwards to keep the strip away from upper and lower edges of the slit.
Although the use of the continuous coating apparatus disclosed in U.S. Pat. No. 4,763,601 may result in the desirable unscratched coated surface there is a risk of plastically deforming the continuous strip during transportation through the apparatus and during unwinding/winding of the strip. In addition, there is a risk of subjecting the continuous strip to wear by sliding of different layers of the strip against each other on the strip take-up device.
It is a general object of the present disclosure to provide an improved continuous reel-to reel arrangement for transportation of continuous substrate materials. It is a specific object to provide a continuous reel-to-reel arrangement in which the risk of plastically deforming the substrate material during transportation and during unwinding/winding of the substrate material is low and where the risk of subjecting the substrate material to wear is low.
The invention is defined by the appended independent claims. Embodiments are set forth in the dependent claims, in the attached drawings and in the following description.
According to a first aspect, there is provided a continuous reel-to-reel arrangement for transportation of continuous substrate materials from an unwinding material reel to a winding material reel, wherein the substrate material is arranged to be driven through at least one treatment zone. The arrangement comprises at least two guiding rolls arranged to align the substrate material when being rolled off from the unwinding material reel before entering into the at least one treatment zone, and at least two guiding rolls arranged to align the substrate material when exiting the at least one treatment zone before being winded up on the winding material reel. At least one of the guiding rolls arranged to align the substrate material when exiting the at least one treatment zone is a driving roll, and at least one of the guiding rolls arranged to align the substrate material when being rolled off from the unwinding material reel is a braking roll, arranged to apply a constant braking force to the substrate material when the substrate material is driven through the at least one treatment zone.
The winding and unwinding material reels have substantially no effect on the driving and braking of the substrate material. The braking roll is a guiding roll which is physically and functionally separate from the unwinding material reel. The driving roll is a guiding roll which is physically and functionally separate from the winding material reel.
The substrate material may be flexible.
The guiding rolls arranged to align the substrate material rolled off from the unwinding material reel are arranged in such a way that the substrate material may be precisely aligned in the horizontal position as well as in the vertical position of the direction of the moving substrate material while being driven through the at least one treatment zone.
Inside the treatment zone there are no supporting or guiding rolls and the substrate material is suspended freely therein.
When more than one treatment zone is present in the continuous reel-to-reel arrangement, these may be arranged in series in the direction of transportation of the substrate material.
The use of at least one driving roll and at least one braking roll, which are physically and functionally separate from the unwinding and winding material reels, prevent too high forces to act on the unwinding/winding material reels. The tension force acting on the substrate material is increased after the braking roll and decreased after the driving roll and is at its maximum when the substrate material passes through the treatment zone. Thereby, the risk of plastically deforming the substrate material during unwinding/winding may be low. Also, wearing of the substrate material by sliding of different layers of substrate materials against each other on the material reels may be avoided. Further, a possible collapse of the whole winded reel structure is avoided.
With this reel-to-reel arrangement the constant braking force applied to the substrate material by the at least one braking roll ensures that the substrate material is kept in a tensed condition when driven through the at least one treatment zone. Also, the horizontal and vertical position of the substrate material inside the treatment zone is controlled and kept substantially constant independently of the amount of substrate material (number of layers) that is winded on the material reels.
With this reel-to-reel arrangement design the mechanical demands required in the treatment zone can be separated from the mechanical demands put on the guiding rolls and the unwinding/winding material reels.
In one embodiment, the number of guiding rolls arranged to align the substrate material rolled off from the unwinding material reel may be at least three.
In yet an embodiment the number of guiding rolls arranged to align the substrate material when exiting the at least one treatment zone may be at least three.
Also four or more guiding rolls may be arranged to align the substrate material rolled off from the unwinding material reel and four or more guiding rolls may be arranged to align the substrate material when exiting the at least one treatment zone.
The number of guiding rolls arranged to align the substrate material rolled off from the unwinding material reel may be independent of the number of guiding rolls arranged to align the substrate material when exiting the at least one treatment zone.
The radius of the guiding rolls may be larger than what causes plastic deformation of the substrate material due to combination of tensile stress and bending curvature which the substrate material is subject to in the continuous reel-to-reel arrangement.
By using guiding rolls with large enough radius, the substrate material may be transported from one material reel to another in the continuous reel-to-reel arrangement without subjecting the substrate material to tensile stress or bending curvature that could cause plastic deformation of the substrate material.
In one specific embodiment a smallest radius, R, of the guiding rolls at a given tension force, F, may be when the total tensile stress, σtot, acting on the substrate material is equal to the yield point, σ0.2, of a given substrate material.
The total tensile stress, σtot, which the substrate material is subject to in the continuous reel-to-reel arrangement, is the sum of tensile stress due to tension forces, F, and tensile stress due to bending curvature. The yield point is a first point at which permanent deformation of a stressed substrate material begins to take place. For engineering purposes the yield point is taken as the point at which a certain small amount of permanent deformation, here 0.2%, σ0.2, has occurred.
In one embodiment of the continuous reel-to-reel arrangement the braking roll may be enclosed by the substrate material at an angle of about 180°.
The substrate material may be wrapped around the braking roll at an angle of about 180° in order to avoid slipping or sliding between the braking roll and the substrate material.
With a wrap angle of about 180° is here meant an angle of 180°±5°.
The braking roll may be arranged between a first guiding roll, guiding the substrate material at an angle of about 90° to engage the braking roll, and a second guiding roll guiding the substrate material at an angle of about 90° for further transportation to the at least one treatment zone.
With an angle of about 90° is here meant an angle of 90°±5°.
By turning the substrate material as it is transported between the guiding rolls, braking roll and driving roll only one side of the substrate material is mechanically touched. By only using guiding rolls whose axis are directed perpendicular to the direction of the moving substrate material, the risk of scratching the surface of substrate material during the transport from the at least on treatment zone is low.
In one embodiment at least one of the guiding rolls arranged to align the substrate material rolled off from the unwinding material reel before entering into the at least one treatment zone, may provide the substrate material with a voltage.
For some applications a substrate material biased with a voltage may be preferred in the at least one treatment zone.
In a further embodiment an evacuated environment may be provided in at least a section of the at least one treatment zone.
A typical working vacuum in the treatment zone may be 1-10 mTorr.
The at least one treatment zone may comprise at least one coating chamber.
In this coating chamber deposition techniques such as PVD and CVD may be used.
One of the guiding rolls arranged to align the substrate material when exiting the at least one treatment zone before being winded up on a winding material reel may be a cooling roll.
The substrate material may be cooled down after exiting the treatment zone by a cooling roll which may be placed close to the exit of the treatment zone. It may comprise a heat absorbing material which should be able to quickly take up the heat from the substrate material by conduction and transport the heat from the substrate material contact area.
Suitable cooling roll surfaces could be any metal with good heating conductivity that will not smear or react with the freshly deposited surface of the substrate material. Alternatively, a heat conductive ceramic material such as aluminium oxide could be used.
The substrate material may be any one of a strip, a wire, and a foil.
The substrate material may be substantially flat or being formed in three dimensions. Substrate materials may for example be nickel plated copper alloys e.g. brass or bronze, stainless steel, aluminium, etc.
According to a second aspect, there is provided a system comprising at least two of the continuous reel-to-reel arrangements described above, wherein the at least one treatment zone is common for the at least two continuous reel-to-reel arrangements, and wherein at least two substrate materials are arranged substantially in parallel when driven through the at least one common treatment zone.
This system enables simultaneous transportation of more than one substrate material through the at least one common treatment zone without having the different substrate materials touching each other. Each different substrate material pass individual adjusting guiding rolls including braking/driving rolls in order to precisely keep the right tension and position of the substrate material when passing through the at least one treatment zone.
According to a third aspect there is provided a method of treating at least one continuous substrate material, the method comprising the steps of: unwinding the, at least one substrate material from at least one unwinding material reel, guiding the at least one substrate material to at least one treatment zone by the use of at least two guiding rolls, treating the at least one substrate material in the at least one treatment zone, and winding up the at least one substrate material on at least one winding material reel, wherein the method comprises a step of driving and a step of braking the at least one substrate material.
According to a fourth aspect there is provided a method of feeding at least one continuous substrate material to at least one treatment zone, the method comprising the steps of unwinding the at least one substrate material from at least one unwinding material reel, guiding the substrate material at an angle of about 90° around a first guiding roll to engage a braking roll, enclosing the braking roll by the substrate material at an angle of about 180°, guiding the substrate material at an angle of about 90° around a second guiding roll and entering the at least one treatment zone.
According to a sixth aspect there is provided a continuous reel-to-reel apparatus for transportation of continuous substrate materials from a pay-out chamber to a take-up chamber, wherein the substrate material is arranged to be driven through at least one treatment zone, wherein the pay-out chamber comprises at least two guiding rolls arranged to align the substrate material rolled off from an unwinding material reel in the pay-out chamber before entering into the at least one treatment zone, and wherein the take-up chamber comprises at least two guiding rolls arranged to align the substrate material when exiting the at least one treatment zone before being winded up on a winding material reel in the take-up chamber. At least one of the guiding rolls in the take-up chamber is a driving roll, and at least one of the guiding rolls in the pay-out chamber is a braking roll, arranged to apply a constant braking force to the substrate material when the substrate material is driven through the at least one treatment zone.
The number of guiding rolls arranged to align the substrate material rolled off from the unwinding material reel in the continuous reel-to-reel apparatus may be at least three.
The above, as well as other aspects, objects and advantages of the present disclosure, will be better understood through the following illustrative and non-limited detailed description, with reference to the appended drawings.
Inside the treatment zone 6 there are no guiding rolls 5 or auxiliary guiding rolls 7 and the substrate material 3 is suspended freely therein. In the embodiment shown in
The unwinding material reel 2 and the guiding rolls 5 arranged to align the substrate material 3 before entering the treatment zone 6 are arranged in a so called pay-out chamber 10,
The winding and unwinding material reels 2, 4 have substantially no effect on the driving/braking of the substrate material 3 in this continuous reel-to-reel arrangement 1. The braking roll 12 is a guiding roll 5 which is physically and functionally separate from the unwinding material reel 2. The driving roll 13 is a guiding roll 5 which is physically and functionally separate from the winding material reel 4.
The guiding rolls 5 arranged to align the substrate material 3 rolled off from the unwinding material reel 2 are arranged in such a way that the substrate material 3 may be precisely aligned in the horizontal position as well as in the vertical position of the direction of the moving substrate material 3 while being driven through the at least one treatment zone 6.
The use of at least one driving roll 13 and at least one braking roll 12 prevent too high forces to act on the unwinding/winding material reels 2, 4. The tension force acting on the substrate material 3 is increased after the braking roll 12 and decreased after the driving roll 13 and is at its maximum when the substrate material 3 passes through the treatment zone 6. Thereby, the risk of plastically deforming the substrate material 3 during unwinding/winding is low. Also, wearing of the substrate material 3 by sliding of different layers of substrate materials 3 against each other on the material reels 2, 4 is avoided. Further, a possible collapse of the whole winded reel structure is avoided.
The constant braking force applied to the substrate material 3 by the at least one braking roll 12 ensures that the substrate material 3 is kept in a tensed condition when driven through the treatment zone 6. Also, the horizontal and vertical position of the substrate material 3 inside the treatment zone 6 is controlled and kept substantially constant independently of the amount of material (number of layers) that is winded on the material reels 2, 4.
A typical substrate material 3 that may be handled in this reel-to-reel arrangement 1 has a thin sheet metal backbone (0.05-0.2 mm in thickness) with a width ranging from 2 mm up to 5 mm. A thin sheet metal having a distributed weight of ρ1, and being suspended between two points of equal horizontal level at a distance L from each other and being subject to a tension force F will have a curvature described by the formula:
Y=a×(cos h(X/a)−1),
where a is calculated from
a=L/(2×arcsin h(g×ρ1×L/(2×F)))
in which g is the earth gravity acceleration.
In order to control the horizontal position of the substrate material 3 without too much of curvature it is important that the tension of substrate material 3 is correct and within a certain tolerance region.
Given the theoretical expressions above, if the tension force, F, applied to a substrate material 3 with a distributed weight in the order of 5 grams per meter is 20 to 25 N and the suspension length of the substrate material 3 is 4 meters, the resulting curvature of the substrate material 3 will have a lowest point of approximately 4-5 mm below the suspension points.
The braking roll 12/driving roll 13 shown in
The material of the guiding rolls 5 should be chosen such that there is a large friction between the guiding roll 5 and the substrate material 3. The material of the guiding rolls 5 should also be chosen such that there is a low risk of scratching the substrate material 3.
The driving roll 13 in the take-up chamber 11 may be propelled by an external electrical motor.
The braking roll 12 may be arranged between a first guiding roll 5, guiding the substrate material 3 at an angle of about 90° to engage the braking roll 12, and a second guiding roll 5 guiding the substrate material 3 at an angle of about 90° for further transportation to the at least one treatment zone 6. By turning the substrate material 3 as it is transported between the guiding rolls 5, braking roll 12 and driving roll 13, only one side of the substrate material 3 is mechanically touched. By only using guiding rolls 5 whose axis are directed perpendicular to the direction of the moving substrate material 3, the risk of scratching the coated surface of the substrate material 3 during the transport from the at least one treatment zone 6 is low. In this way, a substrate material 3 that has an extra sensitive side, such as electrical contact strips, as well as strip material stamped and formed in the 3rd dimension may be transported through the at least one treatment zone 6 without damaging the often sensitive connector pins.
The angle of about 90° is a preferred angle. In the geometry shown in the figures of the continuous reel-to-reel arrangement 1 of this disclosure, the optimal angle is about 90±5°. Deviations from this angle may result in undesirable twisting of and tension in the substrate material 3. Continuous reel-to-reel arrangements 1 with other guiding roll 5 geometries and other guiding angles are also possible. Such arrangements 1 would, however, result in a more complicated geometric structure which would be more complicated and more space requiring to implement.
The radius of the guiding rolls 5 should be larger than what causes the substrate material 3 to be deformed due to combination of tensile stress and bending curvature which the substrate material 3 is subject to in the continuous reel-to-reel arrangement 1. By using guiding rolls 5 with large enough radius, the substrate material 3 may be transported from one material reel 2, 4 to another in the continuous reel-to-reel arrangement 1 without being subject to tensile stress or bending curvature that could cause plastic deformation of the substrate material 3.
A minimum guiding roll 5 radius which may be used for a specific substrate material 3 may be derived from the following calculations: Elongation of a substrate material 3 due to bending curvature is ε=ΔL/L, wherein L is the geometrical length of a substrate material 3 having thickness t. The substrate material 3 is wrapped around a guiding roll 5 with radius R with a contact angle α. Thereby, L=α(R+t/2). The outer surface of the strip is elongated a(r+t). Thus the elongation due to bending curvature may be written ε=α[(R+t)−(R+t/2)]/α[R+t/2]=t/(2R+t), wherein t is presumed to be tR=>ε=t/2R
The tensile stress in the substrate material 3 due to bending curvature, σB, is E×ε=σB, wherein E is the Young's modulus of the specific substrate material.
The total tensile stress in the substrate material 3 is then σtot=σB+σp, wherein σp is the tensile stress due to tension forces, F, acting on the substrate material 3 and may be expressed as σp=F/A, wherein A is the cross sectional area of the substrate material 3.
The smallest radius, R, of a guiding roll 5, which may be used without plastically deforming the substrate material 3, at a given tension force, F, is when the total tensile stress, σtot, is equal to the yield point, σ0.2, of a given substrate material 3.
The yield point is a first point at which permanent deformation of a stressed substrate material begins to take place. For engineering purposes the yield point is taken as the point at which a certain small amount of permanent deformation, here 0.2%, σ0.2, has occurred in the substrate material 3.
A specific example with a stainless steel strip having a Young's modulus of 200 MPa (N/mm2), a yield point, σ0.2, of 290 MPa (N/mm2), a strip width of 3 mm and a strip thickness of 0.1 mm, gives a smallest radius of the guiding rolls 5 of 49 mm if the strip is stretched with a tension force, F, of 25 N. If the tension force, F, is 30 N, the radius should be increased to at least 53 mm to avoid plastic deformation of the substrate material 3.
The tension force, F, acting on the substrate material 3 is at its maximum when the substrate material 3 passes through the treatment zone 6. The tension force acting on the substrate material 3 is increased after the braking roll 12 and decreased after the driving roll 13. Thereby, the risk of plastically deforming the substrate material 3 during unwinding/winding is low.
With this reel-to-reel arrangement 1 design the mechanical demands required in the treatment zone 6 can be separated from the mechanical demands put on the devices in the pay-out chamber 10 and take-up chamber 11.
During the deposition of materials onto the substrate material 3 in the deposition chamber 8, 8′, energy in form of condensation heat, thermal radiation and ion flux will increase the temperature of the substrate material 3. Since the process normally takes place in a controlled vacuum atmosphere with a pressure in the order of 1-10 mTorr, convection cooling is negligible. The only significant cooling method is by thermal radiation or conduction. A rough and simplified calculation model shows that given a normal deposition process using a substrate material 3 which is a thin and flat strip, will take more than 20 seconds to cool down from 600 K down to 400 K just by radiation cooling. In many process situations, this is a too long time since the transportation time from the deposition chamber 8, 8′ to the winding material reel 4 will be below this time frame. Since the driving roll 13 and other guiding rolls 5 in the take-up chamber 11 are made of materials that are chosen for their large friction and low tendency to scratch the substrate material 3, they are not very resistant to elevated temperatures. In order to cool down the substrate material 3 to temperatures suited for the guiding rolls 5, a cooling roll 14 (
The cooling roll 14 should be able to quickly absorb the heat from the substrate material 3 by conducting and transporting the heat from the substrate material 3 contact area. Suitable cooling roll 14 surfaces could be any metal with good heat conductivity that will not smear or react with the freshly deposited surface of the substrate material 3. An alternative material choice could be a heat conductive ceramic material such as aluminium oxide.
One of the guiding rolls 5 in the pay-out chamber 10 (preferably the second last or the last guiding roll 5) is carrying a voltage, i.e. a biasing roll 15,
Depending on the preferred orientation of the substrate material 3, an end stage roll (not shown) may be included before the treatment zone 6. This end stage roll may be used if the substrate material 3 is to be fed in horizontal position through the deposition zone 6.
A system in which at least two continuous reel-to-reel arrangements 1 are arranged may be used for simultaneous transportation of at least two substrate materials 3.
In
The number of continuous reel-to-reel arrangements 1 in the system may vary. In some applications as few as two arrangements 1 are used in the system and sometimes a system may comprise up to ten or more arrangements 1.
The system enables simultaneous transportation of more than one substrate material 3 through at least one common treatment zone 6 without having the different substrate materials 3 touching each other. Each different substrate material 3 pass individual adjusting guiding rolls 5 (that also can serve as biasing roll 15 or cooling roll 14), as seen in
The position and distance between the substrate materials 3 in the system are also dependent on the individual tension of the substrate materials 3 which is controlled by the braking rolls 12. All guiding rolls 5 may rotate individually for each substrate material 3 that is fed through the treatment zone 6. The driving roll 13 normally rotates at a similar speed as the other driving rolls 13 around the common axis. However, in case of that the substrate material 3 is stopped (e.g. if the substrate material 3 is at the end), a torque limited brake will release inside that specific driving roll 13 and it will stop rotating, while the other substrate materials 3 can continue their motion in the system independently.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1250680-4 | Jun 2012 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/062625 | 6/18/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61663834 | Jun 2012 | US |
