U.S. patent application number 14/238177 was filed with the patent office on 2015-02-12 for substrate rollers.
The applicant listed for this patent is Preston Clover, Bruce Hachtmann, Ross Porter, Aaron Quitugua-Flores. Invention is credited to Preston Clover, Bruce Hachtmann, Ross Porter, Aaron Quitugua-Flores.
Application Number | 20150041514 14/238177 |
Document ID | / |
Family ID | 47746882 |
Filed Date | 2015-02-12 |
United States Patent
Application |
20150041514 |
Kind Code |
A1 |
Hachtmann; Bruce ; et
al. |
February 12, 2015 |
SUBSTRATE ROLLERS
Abstract
A magnetically enhanced roller for handling of magnetically
attractable substrates comprises a rotatably fixed shaft and a
sleeve circumscribing the rotatably fixed shaft. The sleeve
configured to rotate around the shaft. The roller further includes
an array of magnets adjacent to the shaft. Individual magnets of
the array of magnets are oriented to provide magnetic field lines
along a direction orthogonal to the rotatably fixed bearing
shaft.
Inventors: |
Hachtmann; Bruce; (San
Martin, CA) ; Clover; Preston; (Sunnyvale, CA)
; Porter; Ross; (Philadelphia, PA) ;
Quitugua-Flores; Aaron; (Palo Alto, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hachtmann; Bruce
Clover; Preston
Porter; Ross
Quitugua-Flores; Aaron |
San Martin
Sunnyvale
Philadelphia
Palo Alto |
CA
CA
PA
CA |
US
US
US
US |
|
|
Family ID: |
47746882 |
Appl. No.: |
14/238177 |
Filed: |
August 23, 2012 |
PCT Filed: |
August 23, 2012 |
PCT NO: |
PCT/US2012/052159 |
371 Date: |
September 15, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61527087 |
Aug 24, 2011 |
|
|
|
Current U.S.
Class: |
226/1 ; 242/538;
242/615.2 |
Current CPC
Class: |
B65H 20/00 20130101;
B65H 18/145 20130101; B65H 27/00 20130101; B65H 2701/1714 20130101;
B65H 2404/191 20130101; B65H 16/00 20130101; B65H 18/00 20130101;
B65H 2301/5131 20130101; B65H 2515/71 20130101; B65H 2301/3112
20130101; B65H 2301/31122 20130101; B65H 23/26 20130101; B65H
2801/87 20130101 |
Class at
Publication: |
226/1 ;
242/615.2; 242/538 |
International
Class: |
B65H 23/26 20060101
B65H023/26; B65H 18/00 20060101 B65H018/00; B65H 20/00 20060101
B65H020/00; B65H 16/00 20060101 B65H016/00 |
Claims
1. A roller for handling a substrate web, comprising: (a) a
rotatably fixed shaft; (b) a sleeve circumscribing said rotatably
fixed shaft, wherein said sleeve is configured to rotate about the
shaft; and (c) an array of magnets adjacent to the shaft, wherein
individual magnets of said array of magnets are oriented so as to
provide magnetic field lines propagating along a direction
orthogonal to said rotatably fixed shaft, which magnetic field
lines are configured to couple to said substrate directed adjacent
to said sleeve.
2. (canceled)
3. The roller of claim 1, further comprising a pole piece adjacent
to said rotatably fixed shaft, wherein an individual magnet of said
array of magnets is attached to said pole piece
4-8. (canceled)
9. The roller of claim 1, wherein said roller is configured to
direct said substrate web adjacent to said sleeve upon the
application of said magnetic field lines, wherein said substrate
web is directed at a wrap angle.
10. The roller of claim 9, wherein said array has a radial size
that is larger than said wrap angle.
11. The roller of claim 1, wherein said array has a radial size
that is less than or equal to about 1/2 of a circumference of said
sleeve.
12. (canceled)
13. The roller of claim 1, wherein said array of magnets comprises
a first magnet having a north pole adjacent to said rotatably fixed
shaft and a south pole adjacent to said sleeve, and a second magnet
having a north pole adjacent to said sleeve and a south pole
adjacent to said rotatably fixed shaft.
14. The roller of claim 13, wherein said array of magnets further
comprises a third magnet having a north pole adjacent to said
rotatably fixed shaft, and a south pole adjacent to said
sleeve.
15. The roller of claim 14, wherein said second magnet is radially
disposed between said first and third magnets.
16. The roller of claim 14, wherein said third magnet is radially
disposed between said first and second magnets.
17. The roller of claim 1, wherein said sleeve and/or said
rotatably fixed shaft are cylindrical.
18. The roller of claim 1, wherein an individual magnet of said
array of magnets is separated from said sleeve by a gap.
19. A method for moving a substrate web, comprising: (a) providing
a roller, said roller comprising: (i) a rotatably fixed shaft; (ii)
a sleeve circumscribing said rotatably fixed shaft, wherein said
sleeve is configured to rotate about the shaft; and (iii) an array
of magnets adjacent to the shaft, wherein individual magnets of
said array of magnets are oriented so as to provide magnetic field
lines propagating along a direction orthogonal to said rotatably
fixed shaft; and (b) providing a substrate web comprising a
magnetically attractable material adjacent to said sleeve; and (c)
moving said substrate web upon the coupling of said substrate web
to said magnetic field lines.
20-21. (canceled)
22. The method of claim 19, wherein (b) comprises attracting said
substrate web to said roller with the aid of said magnetic field
lines.
23. The method of claim 19, further comprising providing
translational motion to said substrate web.
24. (canceled)
25. The method of claim 19, wherein (c) comprises moving said
substrate web adjacent to said sleeve at a warp angle.
26. The method of claim 19, wherein said array of magnets comprises
a first magnet having a north pole adjacent to said rotatably fixed
shaft and a south pole adjacent to said sleeve, and a second magnet
having a north pole adjacent to said sleeve and a south pole
adjacent to said rotatably fixed shaft.
27. The method of claim 19, wherein said array of magnets further
comprises a third magnet having a north pole adjacent to said
rotatably fixed shaft and a south pole adjacent to said sleeve.
28. The method of claim 27, wherein said second magnet is radially
disposed between said first and third magnets.
29. (canceled)
30. A roller for moving a substrate. comprising: (a) a sleeve
circumscribing a rotatably fixed shaft, wherein said sleeve is
configured to rotate about said rotatably fixed shaft and (b) an
array of magnets disposed between said sleeve and said rotatably
fixed shaft, wherein said array of magnets comprises two or more
magnets that have poles that are oriented in an anti-parallel
configuration so as to provide magnetic field lines propagating
along a direction orthogonal to said rotatably fixed shaft, which
magnetic field lines are configured to couple to said substrate
disposed adjacent to said sleeve.
31. A roller system, comprising: (a) a roller as in claim 1; (b) a
pay-out roll and uptake roll; and (c) a substrate web that is
directed about or along the roller from said pay-out roll to said
uptake roll.
Description
CROSS-REFERENCE
[0001] This application claims priority to U.S. Provisional Patent
Application Ser. No. 61/527,087, filed Aug. 24, 2011, which
application is entirely incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] Thin metal foils are often used to make a variety of useful
products ranging from stamped items for automobiles to substrates
for high tech coatings for electronic applications. Regardless of
the specific product, thin metal foil substrates or webs in roll
form are transported through some type of machine that performs one
or more operations to make a final product. The handling of the
webs during the processing can become difficult when extreme
physical conditions are required, such as high temperatures, for
example. In electronic applications where thin layers of material
are coated onto the webs, the coatings may be sensitive to contact
with various components of the coating equipment, which may lead to
loss of yield in the manufacturing process. One such example is a
thin film solar cell that is deposited on a stainless steel foil
substrate where contact of the coating with transport rollers may
create small electronic defects in the solar cell.
SUMMARY
[0003] This disclosure provides rollers for thin magnetic foil
substrates with improved contact resistance for small wrap
angles.
[0004] In an aspect of the invention, a roller for handling a
substrate web comprises a rotatably fixed shaft and a sleeve
circumscribing the rotatably (or rotationally) fixed shaft. The
sleeve can be configured to rotate about the shaft. The roller
further comprises an array of magnets adjacent to the shaft.
Individual magnets of the array of magnets are oriented so as to
provide magnetic field lines propagating along a direction
orthogonal to the rotatably fixed shaft. The magnetic field lines
are configured to couple to the substrate directed adjacent to the
sleeve. In some examples, the rotatably fixed shaft does not rotate
during rotation of the sleeve.
[0005] In another aspect of the invention, a roller for moving a
substrate comprises a sleeve circumscribing a rotatably fixed
shaft, wherein the sleeve is configured to rotate about the
rotatably fixed shaft. The roller further comprises an array of
magnets disposed between the sleeve and the rotatably fixed shaft.
The array comprise two or more magnets that have poles that are
oriented in an anti-parallel configuration so as to provide
magnetic field lines propagating along a direction orthogonal to
the rotatably fixed shaft, which magnetic field lines are
configured to couple to the substrate disposed adjacent to the
sleeve.
[0006] In another aspect of the invention, a roller system
comprises a roller as described above or elsewhere herein, alone or
in combination, a pay-out roll and uptake roll, and a substrate web
that is directed about or along the roller from the pay-out roll to
the uptake roll.
[0007] In another aspect of the invention, a method for moving a
substrate web comprises providing a roller, as described above or
elsewhere herein, and providing a substrate web adjacent to a
sleeve of the roller. The substrate web is moved upon the coupling
of the substrate web to magnetic field lines provided by the
roller.
[0008] Additional aspects and advantages of the present disclosure
will become readily apparent to those skilled in this art from the
following detailed description, wherein only illustrative
embodiments of the present disclosure are shown and described. As
will be realized, the present disclosure is capable of other and
different embodiments, and its several details are capable of
modifications in various obvious respects, all without departing
from the disclosure. Accordingly, the drawings and description are
to be regarded as illustrative in nature, and not as
restrictive.
INCORPORATION BY REFERENCE
[0009] All publications, patents, and patent applications mentioned
in this specification are herein incorporated by reference to the
same extent as if each individual publication, patent, or patent
application was specifically and individually indicated to be
incorporated by reference.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0011] FIG. 1 is a schematic isometric sketch of a roller.
[0012] FIG. 2 is a schematic isometric sketch of an alternative
design for a roller.
[0013] FIG. 3 is a schematic cross sectional side view of two
roller arrangements for driving a web.
[0014] FIG. 4 is a schematic cross sectional layout of a web
handling (or roller) system for a manufacturing operation.
[0015] FIG. 5a is schematic cross sectional representation of a
vacuum drum type coating machine.
[0016] FIG. 5b is schematic cross sectional representation of a
vacuum drum type coating machine which avoids roller contact with
the coated side of the substrate.
[0017] FIG. 6 is a schematic cross sectional view of a roller
showing the basic concept of magnetically enhancing the roller for
use with thin magnetic foil substrates.
[0018] FIG. 7 is a schematic cross sectional view of a magnetically
enhanced roller utilizing a semi-circular pole piece.
DETAILED DESCRIPTION
[0019] While various embodiments of the invention have been shown
and described herein, it will be obvious to those skilled in the
art that such embodiments are provided by way of example only.
Numerous variations, changes, and substitutions may occur to those
skilled in the art without departing from the invention. It should
be understood that various alternatives to the embodiments of the
invention described herein may be employed in practicing the
invention.
[0020] The term "rotatably fixed," as used herein, can refer to a
structure that does not rotate. In some examples, a rotatably fixed
structure does not rotate when another structure circumscribing or
circumscribed by the rotatably fixed structure rotates in relation
to the rotatably fixed structure.
[0021] An aspect of the invention provides a roller for handling a
substrate web. The roller comprises a rotatably fixed shaft and a
sleeve circumscribing the rotatably fixed shaft. The sleeve can be
configured to rotate about the shaft. The rotatably fixed shaft can
be configured such that the shaft does not rotate while the sleeve
rotates. The roller further comprises an array of magnets adjacent
to the shaft. Individual magnets of the array of magnets are
oriented so as to provide magnetic field lines propagating along a
direction orthogonal to the rotatably fixed shaft. The magnetic
field lines are configured to couple to the substrate directed
adjacent to the sleeve.
[0022] The magnetic field lines may propagate away from said shaft
(and towards said sleeve) along an angle of at least about
0.degree., 5.degree., 10.degree., 20.degree., 30.degree.,
40.degree., 50.degree., 60.degree., 70.degree., 80.degree., or
90.degree. from a vector that is normal to a surface of said
rotatably fixed shaft. In an example, when said angle is 0.degree.,
said magnetic field lines propagate along a direction that is
orthogonal to said rotatably fixed shaft.
[0023] In some embodiments, the shaft does not rotate. However, in
some cases, the shaft may rotate, such as, e.g., along a direction
that is opposite to the direction of rotation of the sleeve.
[0024] In some cases, the shaft is rotatable fixed by attachment to
a support member, and the sleeve is permitted to rotate by
decoupling the sleeve from the shaft. The roller can include one or
more separation members to separate the sleeve from the shaft. The
separation members can be ball bearings. The sleeve can be
configured to rotate around (or about) the shaft with the aid of
one or more bearings. For instance, the roller can include at least
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or
100 bearings, which may be situated at an opposing end of the
sleeve. The bearings can be ball bearings. In some cases, a
separation member can be a spacer that enables the sleeve to be
rotatably decoupled from the shaft.
[0025] The roller can be cylindrical in shape. In some cases, the
shaft and/or the sleeve can be cylindrical. The sleeve can be
removable from the roller, such as by sliding the sleeve off of the
roller.
[0026] The roller can include a pole piece adjacent to the
rotatably fixed shaft. An individual magnet of the array of magnets
can be attached to the pole piece.
[0027] The array of magnets can include at least 2, 3, 4, 5, 6, 7,
8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 magnets. The array
of magnets can comprise a magnet formed of a ferromagnetic
material. In some cases, the array of magnets can comprise a magnet
formed of iron, nickel, cobalt or combinations thereof. In some
examples, the array of magnets comprises a magnet formed of one or
more rare earth metals. Alternatively, the array of magnets can
include one or more electromagnets, which may be adapted to provide
a magnetic field upon the application of power (or electricity) to
the electromagnets.
[0028] In some cases, the roller can be configured to direct the
substrate web adjacent to the sleeve upon the application of the
magnetic field lines, or upon bringing the substrate web in
proximity to the sleeve such that the substrate web is attracted by
the magnetic field lines. The substrate web can be directed at a
wrap angle (as may be measured in relation to a tangent to the
sleeve). In some situations, the array has a radial size that is
larger than the wrap angle. The array may have a radial size that
is less than or equal to about 99%, 90%, 80%, 70%, 60%, 50%, 40%,
30%, 20%, 10%, or 5% of the circumference (2 .pi.* sleeve radius)
of the sleeve. In some examples, the array has a radial size that
is less than or equal to about 1/2, 1/3, 1/4, 1/5, 1/6, 1/7, or 1/8
of the circumference of the sleeve.
[0029] The array of magnets can include a first magnet having a
north pole adjacent to the rotatably fixed shaft and a south pole
adjacent to the sleeve, and a second magnet having a north pole
adjacent to the sleeve and a south pole adjacent to the rotatably
fixed shaft. The array of magnets can further comprise a third
magnet having a north pole adjacent to the rotatably fixed shaft
and a south pole adjacent to the sleeve. The second magnet can be
radially disposed between the first and third magnets.
Alternatively, the third magnet can be radially disposed between
the first and second magnets.
[0030] In some cases, an individual magnet of the array of magnets
is separated from the sleeve by a gap. The gap can permit the
sleeve to rotate without coming in contact with an individual
magnet of the array of magnets.
[0031] Rollers provided herein may enable movement or translation
of a substrate web without substantial bending or other deformation
that may adversely impact the substrate web. In some cases, the
substrate web can be translated with reduced friction, thereby
aiding in improving processing efficiency and providing energy
savings.
[0032] The substrate web can be formed of any material that
magnetically attractable--e.g., a material that moves or deforms in
the presence of an applied magnetic field. In some examples, the
substrate web is provided for use in manufacturing photovoltaic
(PV) solar cells. However, other use cases are possible. For
example, the roller may be used to move or direct a substrate web
that includes data, such as, e.g., video, still pictures, or other
information. For example, the substrate web can be a magnetic
recording medium.
[0033] The roller can be used to move or otherwise translate a
substrate web or other support structure. In another aspect of the
invention, a method for moving a substrate web comprises providing
a roller, as described elsewhere herein. For instance, the roller
can comprise a rotatably fixed shaft, a sleeve circumscribing the
rotatably fixed shaft, and an array of magnets adjacent to the
shaft. Individual magnets of the array of magnets are oriented so
as to provide magnetic field lines propagating along a direction
orthogonal to the rotatably fixed shaft. Next, a substrate is
provided adjacent to the sleeve. The substrate web is then moved
upon the coupling of the substrate web to the magnetic field
lines.
[0034] The substrate web in some cases is coupled to the magnetic
field lines by bringing the substrate web in proximity to the
magnetic field lines, such as, for example, in proximity to the
sleeve. In some cases, the substrate web is brought in contact with
the sleeve. The substrate may be attracted to the substrate web
with the aid of the magnetic field lines.
[0035] In some examples, the substrate web comprises a magnetically
attractable material, as described elsewhere herein. In an example,
the substrate web is formed of stainless steel.
[0036] In some cases, the substrate web is moved with the aid of
the roller by providing translational motion to the substrate web.
Translational motion can be provided along a tangential direction
of the sleeve. For example, the substrate web can be moved or
directed by providing motion to the substrate web along a direction
that is parallel to (and in some cases orthogonal to a longitudinal
axis of) a surface of the sleeve.
[0037] The substrate web can be moved about the sleeve by bringing
the substrate web adjacent to the sleeve and providing
translational motion to the substrate web or the sleeve. In some
cases, the substrate web wraps around the sleeve at a wrap angle
during movement.
[0038] Translational motion can be provided to the substrate web
with the aid of a rolling member, such as a motor (e.g., tension
motor) attached to another roller around which the substrate web
can be wound. In some situations, translational motion can be
provided by rotating the sleeve, such as with the aid of a motor
coupled to the sleeve. For example, the motor can be configured to
rotate the sleeve at a fixed angular velocity, and attraction of
the substrate web to the sleeve (with the aid of the magnetic field
lines) provides frictional force that is sufficient to move the
substrate web along the sleeve.
[0039] Reference will now be made to the figures, wherein like
numerals refer to like parts throughout. It will be appreciated
that the figures are not necessarily drawn to scale. It shall be
understood that the figures are for illustrative purposes only and
are not intended to be limiting.
[0040] The disclosure provides various systems for directing a
substrate support web (also "web" herein). A web may be controlled
and directed through processing equipment using a system of
rollers. Some of the rollers may be driven, while others may act as
idlers.
[0041] Roller systems of the disclosure can include one or more
rollers that are configured to direct a substrate web along one or
more directions. For example, a roller system can direct a
substrate web from a payout roll to a pickup roll. Roller systems
of the disclosure may be suited for thin film deposition processes,
such as deposition processes suited for forming photovoltaic
devices.
[0042] A design for a roller is shown in the isometric sketch of
FIG. 1. A web 1 is shown directed over a roller comprising a
polished sleeve 2, a flange 3, and a bearing shaft 4 running in
bearings 5. The shaft need not be solid (it may be tubular, for
example) and it need not extend all the way through the sleeve, but
it should be rigidly attached to the flanges that are in turn
attached to the sleeve. The bearings can be supported as indicated
schematically by blocks 6. The web 1 may make contact with the
sleeve 2 over at least a portion of its circumference. That angle
of contact between the sleeve 2 and the web 1 may be referred to as
the wrap angle, and is indicated by .theta.. The web 1 may be
transported under some amount of tension `T` which can be supplied
by a driven element (or member) or elements (or members) somewhere
else in the system, such as, for example, a motor or a plurality of
motors that are adapted to provide tension to the web 1. For any
roller that is used to drive the web, the wrap angle and the
coefficient of friction between the web 1 and the roller may
determine the amount of force that can be applied to pull the web
1. The coefficient of friction may be a function of the tension in
the web 1.
[0043] FIG. 2 schematically illustrates another roller system.
Bearing shaft 4 extends through the sleeve as shown by the dashed
lines, and is fixed so that it does not rotate as illustrated
schematically by blocks 7. Bearing 5 is seated in flange 3 or is
directly pressed into polished sleeve 2, depending on sizes as may
be appropriate. This type of roller may allow for a simplified
method of roller alignment at the fixed ends, since the bearings
and their housings do not have to be dealt with at the same
time.
[0044] FIG. 3 is a cross sectional sketch showing two roller
arrangements for driving a web. For simplicity the bearings are not
shown. In arrangement A, web 1 forms a wrap angle .theta. of 180
degrees on the roller. Therefore the web leaves the roller in a
direction parallel to the direction it enters. Practically, it is
difficult to increase the warp angle on a single roller very much
more than this. Arrangement B illustrates a way to double the net
wrap angle to a net 360 degrees by using a pair of rollers. This is
known as the classic "S" wrap for driving a web system using
rollers. The total wrap angle on the two rollers can be increased
significantly beyond 360 degrees by rotating the rollers about the
center point of dashed line 8 by some angle .phi.. A maximum wrap
angle of nearly 270 degrees on each roller occurs just before the
rotated rollers touch the entering or exiting web, and the rollers
themselves are brought together so that they nearly touch.
[0045] As an example of a situation where an improved roller could
be useful, FIG. 4 shows a cross sectional schematic layout of a
simple web handling system for some manufacturing operation. Web 1
from a payout roll of material 9 is transported over roller 10 and
through region 11 where some type of manufacturing operations takes
place. Then the web goes over roller 12 and is rewound on takeup
roll 13. Payout and take-up rolls 9 and 13 are driven, and rollers
10 and 12 are idlers. In this type of layout the wrap angle .theta.
on the rollers is rather small, and it may be at least inconvenient
and certainly more expensive to arrange the system in a way that
makes the angle significantly larger. However, it is often
desirable to maintain the tension in the manufacturing region
between the rollers (by driving them) which could be different from
the unwind and rewind tensions on the supply and takeup rolls, but
with such a small wrap angle this cannot readily be done.
[0046] Another example of a system in which an improved roller may
be used to advantage is illustrated in the cross sectional
schematic representations of two vacuum drum type coating machines
shown in FIG. 5a and FIG. 5b. A drum coating architecture is shown
in FIG. 5a. Basically a driven drum 14 is used to support and
transport web substrate 1 while it is coated at various types of
coating stations 15 arrayed around the circumference of the drum.
The drum is often heated or cooled to provide desired web process
conditions. Rollers 16 are known in the trade as "lay-on rollers"
which are not driven, but have a large wrap angle with the web.
Normally they are fitted with load cells which measure the tension
forces in the web. Rollers 17 are simple idle rollers. Driven
payout and takeup rolls of web material 9 and 13 receive feedback
tension information from the load cells and adjust their response
to maintain a selected tension in the web. A major problem with
this classic setup can occur when the substrate and/or the coating
is sensitive to defects that can be produced by the contact between
the lay-on rollers and the coated side of the web.
[0047] One way to avoid the contact with the coated side of the web
is shown in FIG. 5b. The lay-on rollers are removed, and
repositioned fixed rollers 17 redefine the geometry of the web with
respect to drum 14. The two unavoidable consequences of this
arrangement is first the loss of some coating area around the drum,
so not as many coating stations 15 can be used. And second, the
wrap angle on rollers 17 is small, which can lead to slippage and
false reading from load cells fitted to them. The wrap angle on
rollers 17 can be increased by moving them to positions fairly
distant and above the respective payout and takeup rolls, but the
geometry becomes complicated by the changing sizes of the substrate
rolls during coating, and the machine dimensions become larger
making it more expensive.
[0048] An aspect of the invention provides a magnetically enhanced
roller for improved handling of thin foil magnetic substrates. The
roller comprises a rotatably fixed shaft and a sleeve
circumscribing the rotatably fixed shaft. The sleeve can be
configured to rotate about (e.g., around) the shaft with the aid of
bearings. The roller can include an array of magnets adjacent to
the shaft. The array of magnets can be oriented so as to provide
magnetic field lines along a direction orthogonal to the rotatably
fixed bearing shaft. In some cases, the roller includes a pole
piece that can include an individual magnet of the array of magnets
attached thereto. Such a roller can provide greater contact
friction with a substrate (e.g., substrate web) at small wrap
angles than that which may occur for conventional rollers.
[0049] FIG. 6 is a cross sectional view of a roller that has been
magnetically enhanced it for use with thin magnetic foil
substrates, such as steel or other ferromagnetic materials (e.g.,
iron, nickel, cobalt, rare earth metals). In the illustrated
example, the roller comprises a shaft or tube (dashed circle) 4 and
sleeve 2. The roller can be similar to that shown in FIG. 2, where
the shaft 4 is held fixed while the sleeve 2 is allowed to rotate
around the shaft on bearings (not shown in this figure).
[0050] In some examples, the sleeve 2 can rotate about the shaft 4
at a rate of at least about 1 revolution per minute (rpm), 2 rpm, 3
rpm, 4 rpm, 5 rpm, 6 rpm, 7 rpm, 8 rpm, 9 rpm, 10 rpm, 20 rpm, 30
rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm, 500
rpm, or 1000 rpm.
[0051] In some examples, the sleeve 2 can be heated with the aid of
resistive heating elements (not shown). In some cases, the sleeve
can be cooled with the aid of a cooling system (not shown).
[0052] With continued reference to FIG. 6, the shaft 4 can include
three rows of magnets 18 attached along the length (orthogonal to
the plane of drawing) of the roller, or at least of sufficient
length to cover the width of the web 1. The poles of the magnets
are inverted from one row to the next as indicated by the north (N)
and south (S) nomenclature. In some cases, the poles may be
inverted from the way they are shown in FIG. 6. Sleeve 2 can be
made from a non-magnetic material so that the magnetic lines of
force 19 can penetrate the sleeve with little attenuation and
couple into magnetic web 1.
[0053] Suitable materials that may be used to form the sleeve 2
include, without limitation, copper, molybdenum, chromium, gold,
silver, platinum, aluminum, steel, stainless steel, and
combinations thereof. In an example, the sleeve is formed of 300
series stainless steel.
[0054] During use, the magnetic field generated by the magnets
attracts the web 1 towards the sleeve 2. Any extra frictional force
between the web 1 and sleeve 2 created by the magnetic attraction
may be sufficient to allow a small wrap angle roller to be used as
a driver or load cell roller in various web handling situations,
where it may not function as such otherwise. In some low wrap angle
web handling situations, it may be desirable to have the foil slide
over the roller without having the roller turn. This may aid in
adding more tension in the web 4 at some locations. The magnetic
roller may also be used in a static mode if desired, with
additional frictional drag being supplied by the magnetic
fields.
[0055] The magnets 18 can extend radially outward from the shaft 4
of the roller. The magnets 18 are disposed with their poles in an
alternating fashion. A first magnet is disposed with its south pole
adjacent to the shaft 4 and its north pole adjacent to the sleeve
2, and a second magnet adjacent to the first magnet is disposed
with its north pole adjacent to the shaft 4 and its south pole
adjacent to the sleeve 2. A third magnet adjacent to the second
magnet is disposed with its north pole adjacent to the sleeve 2 and
its south pole adjacent to the shaft 4. As an alternative, the
poles of some of the magnets can be aligned. For example, the first
and second magnets can have their north poles adjacent to the shaft
4 and their south poles adjacent to the sleeve 2, or their south
poles adjacent to the shaft 4 and their north poles adjacent the
sleeve 2. The third magnet can have its north and south poles
disposed in an opposite configuration in relation to the first and
second magnets. For example, if the first and second magnets have
their north poles disposed adjacent to the sleeve 2, the third
magnet can have its north pole disposed adjacent to the shaft 4 and
its south pole disposed adjacent to the sleeve 2.
[0056] In some embodiments, the roller can have n magnets, wherein
`n` is greater than or equal to 2. For example, n can be greater
than or equal to 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60,
70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900, or 1000.
If n is equal to 2, then adjacent magnets may have their poles
disposed in an anti-parallel configuration (i.e., north adjacent to
south). If n is greater than 2, then at most n-1 magnets may have
their poles in a parallel configuration (i.e., north adjacent to
north, south adjacent to south), while at least 1 of the n magnets
may have its pole oriented in an anti-parallel configuration with
respect to the n-1 magnets.
[0057] In some embodiments, the magnets 18 do not contact the
sleeve 2. The roller may include a gap between an individual magnet
18 and the sleeve 2. In some examples, the gap has a width less
than or equal to about 6 inches, 5 inches, 4 inches, 3 inches, 2
inches, 1 inch, 0.5 inches, 0.1 inches, 0.01 inches, 0.001 inches,
0.0001 inches, or 0.00001 inches.
[0058] In some examples, the roller has 2, or 3, or 4, or 5, or 6,
or 7, or 8, or 9, or 10, or more magnets. The magnets may be
distributed as desired to effect a predetermined distribution of
magnetic field lines 19. While the roller includes three rows of
magnets 18, the roller can include at least 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 100, 200, 300,
400, 500, or 1000 magnets. Adjacent magnets may be oriented so as
to have poles aligned oppositely in relation to one another.
[0059] Modern magnets made from high energy density magnetic
materials, such as Neodymium Iron Boron and Samarium Cobalt, may
have form factors such that the thickness in the magnetized
direction is substantially equal to the width. In some cases, it
may be practical to make an array of magnets that are attached to a
semi-circular pole piece, rather than have them directly attached
to the central shaft 4. This may permit the array of magnets to be
removed from the roller without removing the shaft. This can
advantageously permit the array of magnets to be tailored to
provide various warp angles, as may be desired in a given
application. The pole piece can be formed of a magnetic material
(e.g., steel, such as low carbon steel). The pole piece can also
permit a smoothing of an otherwise non-uniform magnetic field. FIG.
7 shows a cross sectional view of a magnetically enhanced roller
where semi-circular pole piece 20 is arrayed with several rows of
high energy density magnets 21. The pole piece 20 may be
cylindrical along a direction orthogonal to the plane of the page
of the figure. In the illustrated example, the magnetic sense
alternates with each row, as described elsewhere herein, and
inversion of all the magnets may yield the same functionality. The
array can be rigidly (or fixedly) attached to shaft 4, and roller
sleeve 2 rotates around the fixed array as web 1 is transported.
This semi-circular array of magnets may be combined with or
modified by the flat array of magnets described in U.S. Patent
Publication No. 2010/0266810 ("Magnetic Hold-Down for Foil
Substrate Processing"), which is entirely incorporated herein by
reference.
[0060] With continued reference to FIG. 7, in an embodiment, the
magnetic array is shown to extend over about half of the
circumference of the roller, while the wrap angle of the web is
substantially less. Magnetic flux 19 can couple to the magnetic web
substrate over some of the region where the web does not touch the
roller. However, since the strength of the magnetic flux from the
array of magnets can decrease rapidly with increasing distance from
the array, the coupling with the web can also decrease rapidly.
Therefore, various array sizes in relation to the wrap angle may be
used. The array in some cases is larger than the wrap angle. In
some situations, the array size is less than or equal to about half
the circumference of the roller.
[0061] In some cases, individual magnets of the array of magnets
are in contact with the sleeve and the roller (shaft, array and
sleeve) rotate as a single unit. In such a case, the array of
magnets can be radially disposed around a substantial portion
(e.g., 360.degree.) of the roller.
[0062] A roller system can include multiple rollers. In an example,
a roller system, such as that illustrated in any of FIG. 1, FIG. 2,
FIG. 3, FIG. 4, FIG. 5a or FIG. 5b, comprises rollers as described
in the context of FIG. 6 or FIG. 7. A roller system can include a
single roller (e.g., the roller of FIG. 6 or FIG. 7), or multiple
rollers, each of which plurality of rollers may be as described in
the context of FIG. 6 or FIG. 7.
[0063] Rollers and roller systems of the disclosure may be combined
with or modified by other devices or systems, such as, for example,
those described in U.S. Pat. Nos. 4,047,609, 4,982,691, 7,106,011,
7,352,983, and 7,459,820, which patents are entirely incorporated
herein by reference.
[0064] It should be understood from the foregoing that, while
particular implementations have been illustrated and described,
various modifications can be made thereto and are contemplated
herein. It is also not intended that the invention be limited by
the specific examples provided within the specification. While the
invention has been described with reference to the aforementioned
specification, the descriptions and illustrations of the preferable
embodiments herein are not meant to be construed in a limiting
sense. Furthermore, it shall be understood that all aspects of the
invention are not limited to the specific depictions,
configurations or relative proportions set forth herein which
depend upon a variety of conditions and variables. Various
modifications in form and detail of the embodiments of the
invention will be apparent to a person skilled in the art. It is
therefore contemplated that the invention shall also cover any such
modifications, variations and equivalents. It is intended that the
following claims define the scope of the invention and that methods
and structures within the scope of these claims and their
equivalents be covered thereby.
* * * * *