U.S. patent application number 17/043570 was filed with the patent office on 2021-04-29 for core for coiled sheet metal, manufacturing method, and method for packaging coils.
The applicant listed for this patent is SONOCO-ALCORE OY, SONOCO DEVELOPMENT INC.. Invention is credited to Jordi Casas, Javier Fustero, Marko Ilomaki.
Application Number | 20210122562 17/043570 |
Document ID | / |
Family ID | 1000005361643 |
Filed Date | 2021-04-29 |
![](/patent/app/20210122562/US20210122562A1-20210429\US20210122562A1-2021042)
United States Patent
Application |
20210122562 |
Kind Code |
A1 |
Casas; Jordi ; et
al. |
April 29, 2021 |
CORE FOR COILED SHEET METAL, MANUFACTURING METHOD, AND METHOD FOR
PACKAGING COILS
Abstract
A hollow cylindrical core (1), e.g. paperboard core, for coiled
sheet metal (5), the core (1) being made from at least one ply of
material wound into the shape of a tube, the core having an outer
circumferential surface (2), an inner circumferential surface (3)
and a cavity (4) inside the core (1) which is defined by the inner
circumferential surface (3), and the core (1) being open at least
at one end, wherein the core (1) is provided with a volatile
corrosion inhibitor inside the cavity (4).
Inventors: |
Casas; Jordi; (Barcelona,
ES) ; Fustero; Javier; (Zaragoza, ES) ;
Ilomaki; Marko; (Kotka, FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SONOCO DEVELOPMENT INC.
SONOCO-ALCORE OY |
Hartsville
Kotka |
SC |
US
FI |
|
|
Family ID: |
1000005361643 |
Appl. No.: |
17/043570 |
Filed: |
April 4, 2018 |
PCT Filed: |
April 4, 2018 |
PCT NO: |
PCT/EP2018/058571 |
371 Date: |
September 29, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 2701/522 20130101;
B65H 2701/5112 20130101; B65D 85/672 20130101; B65H 75/10 20130101;
B65B 25/24 20130101 |
International
Class: |
B65D 85/672 20060101
B65D085/672; B65B 25/24 20060101 B65B025/24; B65H 75/10 20060101
B65H075/10 |
Claims
1. A hollow cylindrical core for coiled sheet metal, the core being
made from at least one ply of material wound into the shape of a
tube, the core having an outer circumferential surface, an inner
circumferential surface and a cavity inside the core which is
defined by the inner circumferential surface, and the core being
open at least at one end, wherein the core is provided with a
volatile corrosion inhibiting (VCI) composition inside the
cavity.
2. The hollow cylindrical core according to claim 1, wherein the
outer circumferential surface of the core is left free of any
volatile corrosion inhibiting (VCI) composition.
3. The hollow cylindrical core according to claim 1, wherein the
core is provided with a volatile corrosion inhibiting (VCI)
composition also on the outer circumferential surface of the
core.
4. The hollow cylindrical core according to any one of claims 1-3,
in which the VCI composition is provided as a coating on, or an
impregnation into, the material forming the inner and/or outer
circumferential surface of the core.
5. The hollow cylindrical core of any one of the preceding claims,
in which the VCI composition is provided as a coating on, or an
impregnation into, an additional material layer inserted into the
cavity within the core.
6. The hollow cylindrical core of any one of the preceding claims,
comprising a plurality of material plies wound into a tube.
7. The hollow cylindrical core of claim 6, wherein the material
plies are adhesively bonded to each other.
8. The hollow cylindrical core of any one of the preceding claims,
in which at least one ply of material is a paperboard ply.
9. The hollow cylindrical core of any one of the preceding claims,
further comprising sheet metal wound around the outer circumference
of the core so as to form a metal roll or coil.
10. The hollow cylindrical core of claim 9, further including an
end header at least at one longitudinal end of the metal roll or
coil, wherein the end header is preferably also provided with a
volatile corrosion inhibitor.
11. The hollow cylindrical core of claim 9 or 10, further including
a packaging material wrapped around the metal roll or coil so as to
enclose the metal roll or coil and the volatile corrosion
inhibiting (VCI) composition in a substantially closed
airspace.
12. A method of manufacturing a hollow cylindrical core for coiled
sheet metal, the method comprising the steps of: winding at least
one ply of material into the shape of a tube so as to obtain a core
having an outer circumferential surface, an inner circumferential
surface and a cavity inside the core which is defined by the inner
circumferential surface, the core being open at least at one end,
and providing a volatile corrosion inhibiting (VCI) composition
inside the cavity.
13. The method of claim 12, wherein the outer circumferential
surface of the core is left free of any volatile corrosion
inhibiting (VCI) composition.
14. The method of claim 12, wherein the core is provided with a
volatile corrosion inhibiting (VCI) composition also on the outer
circumferential surface thereof.
15. The method according to any one of claims 12 to 14, in which
the VCI composition is coated onto, or impregnated into, the
material forming the inner and/or outer circumferential surface of
the core.
16. The method of any one of claims 12 to 15, in which at least one
ply of the material is coated or impregnated with the VCI
composition before the ply or plies of material are wound into the
shape of a tube.
17. The method of claim any one of claims 12 to 16, in which at
least one ply of the material is coated or impregnated with the VCI
composition while the ply or plies of material are wound into the
shape of a tube.
18. The method of any one of claims 12 to 17, in which the material
forming the inner and/or outer circumferential surface of the core
is coated or impregnated with the VCI composition after winding the
ply or plies of material into the shape of a tube.
19. The method of any one of claims 12 to 18, in which the VCI
composition is coated onto, or impregnated into, an additional
material layer and the additional material layer is inserted into
the cavity inside the core.
20. The method of any one of claims 12 to 19, wherein the material
plies are adhesively bonded to each other.
21. The method of any one of claims 12 to 20, wherein at least one
ply of material is a paperboard ply.
22. A method of packaging a coiled metal sheet for storage or
transport, comprising the steps of: placing a volatile corrosion
inhibiting (VCI) composition inside the coiled metal sheet, and
wrapping the coiled metal sheet in a packaging material so as to
enclose the coiled metal sheet and the volatile corrosion
inhibiting (VCI) composition in a substantially closed
airspace.
23. The method of claim 22, further comprising the step of
providing a core according to any one of claims 1 to 8 inside the
coiled metal sheet, or winding a metal sheet about a core according
to any one of claims 1 to 8.
24. The method of claim 22 or 23, wherein the packaging material
also includes a volatile corrosion inhibiting (VCI)
composition.
25. The method of any one of claims 22 to 24, wherein the packaging
material is wrapped around the metal coil sufficiently loosely so
as to allow for a circulation of air from the inside of the core
towards the metal coil surfaces to be protected from corrosion.
26. The method of any one of claims 22 to 25, wherein an end header
is provided on at least on one of the open ends of the coiled metal
sheet within the sealed airspace of the packaging material, wherein
the end header is preferably also provided with a volatile
corrosion inhibiting (VCI) composition.
27. Use of a hollow cylindrical core according to any one of claims
1 to 8, or a hollow cylindrical core manufactured in a method
according to any one of claims 12 to 21, for winding sheet metal.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a core for a roll or coil
of metal, such as steel, aluminum, or other metals or alloys, and
to a method of manufacturing such cores.
[0002] The present invention also relates to a method for wrapping
metal coils.
PRIOR ART
[0003] Steel and other metals are often made in sheets having a
length many times greater than their width. The sheets are wound
into coils for storage and transport. The coils of steel may be
stored on pallets for ease in moving and manipulating the
coils.
[0004] The metal materials are rolled into coils with or without
cylindrical cores for supporting the coils. As the cores for
supporting the rolls, large, thick-walled paperboard cores have
been used. The paperboard core helps the wound material develop a
stable roll structure and enables transportation of the
manufactured material to a converting operation. The diameters of
these tubes may range--depending on several factors such as tube
wall thickness, weight of the metal coils to be carried thereon,
purpose of application, etc.--from small inner diameters such as 15
mm to wind e.g. thin sheets of aluminum to large inner diameters
such as 1000 mmm to wind e.g. thick sheets of specialty metals or
alloys.
[0005] Thinner wall cores have also been known which are folded to
be delivered and which are then opened up into an essentially
cylindrical shape, either when putting such a core onto a winding
chuck for winding material sheets thereon, or when inserting such a
core into the inside of a readily wound metal coil.
[0006] In any event, once the metal coils have been formed--with or
without cores --, the coils are usually wrapped in sheets of paper,
such as kraft paper, or plastic material to protect them from
environmental influences.
[0007] U.S. Pat. No. 5,983,598 discloses a method for wrapping
steel coils for storage and transport following their manufacture
at steel mills. The coils are wrapped in paper or a polymeric
packaging material impregnated with a volatile corrosion inhibitor,
such as sodium nitrite, the layer impregnated with the volatile
corrosion inhibitor being in direct contact with the metal
coil.
[0008] According to GB-A-2 131 382, it has been realized that the
interior surfaces of long hollow or tubular articles, such as
pipes, tubes, small arms, rifles and gun barrels, may not be
effectively protected merely by an external wrapping, and it is
therefore suggested to additionally use an anti-corrosive packaging
material for providing corrosion protection to the inside of such
hollow, elongated articles. The packaging comprises an elongated
core member of which at least the exposed exterior surface is
formed from a material impregnated or coated with a volatile
corrosion inhibitor. Such a core member can be made to suit
insertion within articles of various diameters so as to provide
fully effective protection throughout the length of a hollow
product. Such cores may be manufactured by conventional means
utilizing known types of paper or other materials impregnated or
coated in known manner with known volatile corrosion inhibitors,
and serve to enhance the effectiveness of conventional sheet
wrapping materials when used in relation to hollow elongated
articles.
[0009] JP-A-2004/277153 discloses a paper pipe capable of
preventing corrosion and deterioration of metal products,
specifically electronic parts such as diodes which are provided in
a lattice pattern and wound around the paper pipe for
transportation and storage. A corrosion-proof functional layer is
provided at least on the external surface of the paper pipe.
[0010] JP-S51-114717 discloses a process for manufacturing a paper
tube in which said paper-tube is fabricated by coating or
impregnating a primarily ribbon-like paper tube blank with an epoxy
anti-corrosive paint, and a spiraling machine is employed to wind
the thus-coated or impregnated blank into a spiral shape. The tube
is finished by rapidly curing said epoxy anti-corrosive paint on
the spirally wound layers.
[0011] Finally, DE-U1-298 09 872 also forms part of the prior art.
The utility model discloses a winding core configured for
accommodating and storing corrodible parts therein. At least a
radially innermost ply of the core, which will get into contact
with the corrodible part inside the core, is provided with a
corrosion preventing agent.
DISCLOSURE OF THE INVENTION
[0012] It is desirable to provide for a corrosion protection of
metal coils, such as for shipment or storage, e.g. in view of sea
transports or other extreme climate conditions.
[0013] In order to improve on the corrosion protection of metal
rolls or coils, a hollow cylindrical core for coiled sheet metal as
recited in claim 1 is provided. The core is made from at least one
ply of material wound into the shape of a tube, and has an outer
circumferential surface, an inner circumferential surface and a
cavity inside the core which is defined by the inner
circumferential surface. The core is open at least at one end, and
it is provided with a volatile corrosion inhibitor inside the
cavity.
[0014] The core of the present invention can be used for coiled
sheets of metals including, but not limited to, iron, steel,
copper, brass, aluminum, silver, and alloys of these metals, all of
which are frequently found to be susceptible to corrosion under
normal atmospheric and ambient conditions.
[0015] A volatile corrosion inhibitor (abbreviated VCI and also
known as vapor corrosion inhibitor) is an organic or inorganic
chemical compound that is used to protect metallic materials
(including ferrous and non-ferrous metals and alloys) against
corrosion, e.g. oxidation. VCI chemicals are a class of corrosion
inhibiting compounds, which have sufficient vapor pressure to
release molecules from the compound into the air. VCIs slowly
release compounds within a sealed airspace that actively prevent
surface corrosion.
[0016] The VCI on the inside of the core releases corrosion
protective compounds, i.e. VCI chemicals vaporize. Since the core
is open at least at one end, preferably at both its longitudinal
ends, the VCI chemicals diffuse towards the outside of the core and
form a mono-molecular protective layer on the metal surfaces to be
protected, thereby acting to protect the exposed surface of the
metal coil wound around the core from corrosion. The VCI becomes
particularly effective when the metal coil is wrapped in a
packaging material so that the core with the VCI is in the same air
space as the metal coil: the VCI inside the core acts to protect
the metal roll wound onto the core.
[0017] VCI compositions as such are known in the art, and any of
the known VCI compositions can be used for the core of the present
invention. For example, sodium nitrite is known as an effective
volatile corrosion inhibitor when carbon dioxide and water are
present in the air. Sodium nitrite, amine nitrite salts, organic
amines, carboxylic acids and organic amine carboxylic acid salts
have all been disclosed singularly and in combination in volatile
corrosion inhibiting compositions.
[0018] The choice of a specific VCI also depends on the type of
material to be protected from corrosion or oxidation, respectively.
For example, if the material to be protected is aluminum, suitable
VCIs are available to protect the aluminum from oxidation which in
this case would become manifest in a loss of glossiness.
[0019] The hollow cylindrical core of the invention can have any
inner diameter suitable for paperboard cores, e.g. within the range
of 15 mm to 1000 mmm, preferably 100 to 900 mm, more preferably 200
to 800 mm. The inner diameter of the hollow cylindrical core of the
invention can be within a range of about 300 mm to 600 mm, which is
an exemplary diameter range for paperboard cores for the metal
industry. Further possible exemplary inner diameters are within the
range of 350 to 400 mm or within the range of 600 to 700 mm.
[0020] Optional features are recited in the dependent claims and
the description which follows.
[0021] The outer circumferential surface of the core can be left
free of volatile corrosion inhibitor chemicals.
[0022] As an alternative, the volatile corrosion inhibitor can
additionally be provided on the outer circumferential surface of
the core. The VCI on the outer circumferential surface of the core
releases corrosion protective compounds, i.e. VCI chemicals
vaporize. Since the outer circumferential surface of the core is in
direct contact with the innermost surface of the metallic material
coil wound around the core, the corrosion protective compounds are
in direct contact with the innermost surface of the material coil,
thereby forming a mono-molecular protective layer on the innermost
surface of the metallic material coil which is in direct contact
with the outer circumferential surface of the core. Thus, the
innermost surface of the metallic material coil is protected from
corrosion through direct contact with the VCI chemicals. In cases
where gaps between the outer circumferential surface of the core
and the innermost surface of the metallic material coil exist, the
VCI chemicals from the outer circumferential surface, particularly
the VCI chemicals in an area close to the gap, diffuse towards and
into said gap and towards the outside of the core. Providing the
VCI on the outer circumferential surface can be particularly
helpful in preventing corrosion of the metallic material coil when
gaps between the core and the metallic material coil occur during
transportation.
[0023] The volatile corrosion inhibitor can be provided as a
coating on, or an impregnation into, the material forming the inner
circumferential surface of the core. The core as such is thereby
provided with a corrosion prevention function.
[0024] The volatile corrosion inhibitor can further be provided as
a coating on, or an impregnation into, the material forming the
outer circumferential surface of the core. The core as such is
thereby provided with a corrosion prevention function.
[0025] Considering that the metal roll to be protected is on the
outside of the core, whereas the VCI is provided at least
inside--or possibly only inside--of the core, the amount of VCI
inside the core must be sufficiently large so as to provide for a
corrosion protection of the entire metal roll or coil. In general
terms, the activity of a VCI decreases over time, i.e. the more VCI
is used, the longer it remains active. In principle, VCIs can be
said to provide a temporary corrosion protection.
[0026] There are several parameters which determine the amount of
VCI which is needed to provide for a corrosion protection of the
entire coil.
[0027] First of all, the amount of VCI needed is dependent on the
chemical composition, i.e. the type of VCI and its effectiveness in
terms of corrosion protection. Any type of commercially available
VCI that prevents metallic materials from corroding are suitable
for the purpose of this invention. The choice of a specific VCI
hereby also depends on the type of metallic material (e.g. steel,
aluminum or the like) to be protected.
[0028] In cases where the VCI is provided only inside of the core,
the amount of VCI inside the core must be sufficiently large as to
provide for a protection of the entire coil, considering that the
metallic material roll to be protected is on the outside of the
core. Moreover, the amount of VCI needed to provide for a corrosion
protection is dependent on the type of metallic material which is
wound around the core and for which corrosion protection is sought.
Furthermore, the amount of VCI needed to provide for a sufficient
corrosion protection is dependent on the type of material on which
the VCI is impregnated into or coated onto. In addition to that,
the amount of VCI which is needed to provide for a corrosion
protection of the entire coil increases with increasing core size,
increasing amount of metallic material and increasing duration of
protection. Furthermore, the amount of VCI is dependent on the type
of environment for which corrosion protection is sought, i.e. the
amount of VCI which is needed to provide for a corrosion protection
of the entire coil increases for harsh and/or corrosive
environments which can, for example, occur during sea transport due
to corrosive salt water or high-temperature environments which can,
for example, occur due to direct solar radiation.
[0029] Depending on the circumstances, the inner and/or outer
surface of the core can be fully or only partially covered with the
volatile corrosion inhibitor.
[0030] Alternatively or in addition, the volatile corrosion
inhibitor can be provided as a coating on, or an impregnation into,
an additional material layer inserted into the cavity within the
core. The additional material layer could be a sheet that is
inserted into the inside of the core and formed into a round shape
to match the shape of the inner periphery of the core. The
additional material layer could also be e.g. a thin, foldable
forming tube. In any case, additional material layer preferably has
the volatile corrosion inhibitor coated on its surface facing the
inside of the core.
[0031] The hollow cylindrical core can comprise a plurality of
material plies wound into a tube. The material plies can be
spirally wound into a tube. The material plies can be adhesively
bonded to each other by means of glue.
[0032] At least one ply of material can be a paperboard ply. The
hollow cylindrical core can be made from one or several paperboard
plies. Preferably, the material ply or plies constituting the core
are made from thick, soft and porous paperboard which is able to
absorb, i.e. be impregnated with, a significant amount of VCI. The
absorption capacity of the core can, especially in cases where the
VCI is only provided in the cavity of a core, be used to compensate
for the limited area inside the core where the VCI is provided, as
compared to the surface area of the metal coil which is to be
protected from corrosion.
[0033] The hollow cylindrical core may further comprise sheet metal
wound around the outer circumference of the core so as to form a
metal roll or coil.
[0034] The hollow cylindrical core can then further comprise an end
header at least at one longitudinal end of the metal roll or coil,
wherein the end header is preferably also provided with a volatile
corrosion inhibitor. The end header can have a diameter which is
larger than an outside diameter of the core. It protects the edges
of the metal roll and increases the surface area which can be
provided with the VCI.
[0035] The hollow cylindrical core may further include a packaging
material wrapped around the metal roll or coil so as to enclose the
metal roll or coil and the volatile corrosion inhibiting (VCI)
composition in a substantially closed airspace.
[0036] The present invention also provides a method of
manufacturing a hollow cylindrical core for coiled sheet metal
(claim 12), the method comprising the steps of: winding at least
one ply of material--e.g. paperboard--into the shape of a tube so
as to obtain a core having an outer circumferential surface, an
inner circumferential surface and a cavity inside the core which is
defined by the inner circumferential surface, the core being open
at least at one end; and providing a volatile corrosion inhibitor
inside the cavity.
[0037] The outer circumferential surface of the core can be left
free of any volatile corrosion inhibitor. Alternatively, the core
can be provided with a volatile corrosion inhibitor also on the
outer circumferential surface thereof.
[0038] One way of providing a volatile corrosion inhibitor to the
core (i.e. at least inside the cavity, and possibly also on the
outer circumferential surface of the core) is to coat the volatile
corrosion inhibitor onto, or impregnate it into, the material
forming the inner and/or outer circumferential surface of the
core.
[0039] For example, at least one ply of the material forming the
core is coated or impregnated with the VCI before the ply or plies
of material are wound into the shape of a tube. The material ply
coated or impregnated with the VCI could then in principle
correspond to a ply of conventional VCI paper.
[0040] Alternatively or in addition, the material forming the inner
and/or outer circumferential surface of the core is coated or
impregnated with the VCI in an in-line process while manufacturing
the core, i.e. while winding the ply or plies of material into the
shape of a tube.
[0041] Alternatively or in addition, the material forming the inner
and/or outer circumferential surface of the core is coated or
impregnated with the VCI after manufacturing the core, i.e. after
winding the ply or plies of material into the shape of a tube.
[0042] The volatile corrosion inhibitor can be applied by means of
a brush, a sponge, a scrape, a roll, by spraying or the like. The
volatile corrosion inhibitor can be applied in one or several
steps.
[0043] At least one of the end surfaces of the core can be provided
(e.g. coated) with VCI as well, which further increases the surface
area from which the VCI is volatilized.
[0044] The at least one ply of the material coated or impregnated
with the VCI is preferably dried before the ply or plies of
material are wound into the shape of a tube.
[0045] Still alternatively or in addition, the volatile corrosion
inhibitor is coated onto, or impregnated into, an additional
material layer and the additional material layer is inserted into
the cavity inside the core. In this manner, it is possible to also
provide standard paperboard cores with a corrosion protecting
function. The additional material layer can for example have a
shape which substantially coincides with the inner circumferential
surface of the core so that the additional material layer can be
formed into a cylindrical shape and placed inside the cavity. The
surface of the additional material layer which is coated or
impregnated with the VCI should then face towards the inside of the
cavity so as to achieve the desired effect.
[0046] When manufacturing the core, the material plies are
preferably adhesively bonded to each other. This is done by coating
or impregnating the material plies with a glue before winding.
[0047] Finally, the present invention relates to a method of
packaging a coiled metal sheet for storage or transport as recited
in claim 22, comprising the steps of: placing a volatile corrosion
inhibitor inside the coiled metal sheet, and wrapping the coiled
metal sheet in a packaging material so as to enclose the coiled
metal sheet and the volatile corrosion inhibitor in a substantially
closed airspace.
[0048] The method can further comprising the step of providing a
core according to any one of claims 1 to 8 inside the coiled metal
sheet, or winding a metal sheet about a core according to any one
of claims 1 to 8.
[0049] The packaging material can also include a volatile corrosion
inhibitor.
[0050] The packaging material should be wrapped around the metal
coil sufficiently loosely so as to allow for a circulation of air
from the inside of the core towards the metal coil surfaces to be
protected from corrosion.
[0051] The plastic wrap should be sufficiently airtight and so
loose that gases can move inside of the package, so as to make sure
that the VCI in the inside of the core can act to protect the metal
on the outside of the roll. The VCI chemicals will protect the
metal even if the airspace is not totally sealed, but the best
effect is achieved in a sealed airspace. It is important that air
can circulate inside the package.
[0052] The packaging material can for example be a paper, e.g.
kraft paper, or a plastic material, preferably a tear resistant
polymeric material such as polyethylene or polypropylene; it could
also be a laminate of two or more different materials, e.g. plastic
and paper.
[0053] Considering that a corrosion protection is already provided
by the VCI inside the core, it is not necessary for the packaging
material to also have a corrosion protecting function. However, in
many cases a substantially air-tight packaging of the metal coil
will be required anyway, and if packaging materials--e.g. paper or
plastic materials--are used to which a VCI has been added, this can
suitably further enhance the corrosion protection.
[0054] An end header can be provided on at least on one of the open
ends of a roll of sheet metal wound around the core within the
sealed airspace of the plastic wrap, wherein the end header is
preferably also provided with a volatile corrosion inhibitor.
[0055] Finally, the present invention also relates to the use of a
hollow cylindrical core according to any one of claims 1 to 8, or a
hollow cylindrical core manufactured in a method according to any
one of claims 12 to 21, for winding sheet metal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0056] In the enclosed drawings,
[0057] FIG. 1 shows a paperboard core according to the present
invention,
[0058] FIG. 2 shows a metal roll wound on the paperboard core of
FIG. 1,
[0059] FIG. 3 illustrates the behavior of a volatile corrosion
inhibitor (VCI) used in the paperboard core of FIG. 1,
[0060] FIG. 4 is a schematic view of the metal roll of FIG. 3 in a
packaged state, and
[0061] FIGS. 5 and 6 illustrate two possibilities of wrapping a
metal coil using the paperboard core of the present invention.
DESCRIPTION OF EMBODIMENTS
[0062] An embodiment of a paperboard core according to the present
invention, a method of manufacturing the core and a method for
packaging a metal coil using the core will now be described with
reference to the drawings.
[0063] FIG. 1 shows a paperboard core 1 according to the present
invention. The paperboard core 1 is a hollow cylindrical paperboard
core for winding sheet metal. The core 1 is made from at least one
ply of paperboard material wound, e.g. spirally, into the shape of
a tube. The paperboard core can also be a convolute core, though.
One possible example of the paperboard core is a Metallan.RTM.
(trademark owned by Sonoco Products Company) core, which has a
large inner diameter of e.g. 400 mm and is used to wind metal coils
like coated aluminum.
[0064] The core 1 has an outer circumferential surface 2, an inner
circumferential surface 3 and a cavity 4 inside the core 1 which is
defined by the inner circumferential surface 3, and the core in
this embodiment is open at both ends. Strictly speaking it would be
sufficient for the core to be open at one end, but providing the
core with two open ends is beneficial in view of the required
circulation of air through the inside of the core which will be
specified further below.
[0065] In accordance with the invention, the paperboard core 1 is
provided with a volatile corrosion inhibitor inside the cavity 4.
The volatile corrosion inhibitor can for example be provided as a
coating on, or an impregnation into, the paperboard material
forming the inner circumferential surface 3 of the core 1.
[0066] FIG. 2 shows a metal roll 5 wound on the paperboard core 1
of FIG. 1, and FIG. 3 illustrates the behaviour of the volatile
corrosion inhibitor (VCI) provided inside the paperboard core 1:
The VCI in the cavity 4 inside of the core 1 releases corrosion
protective compounds. Since the core 1 is open at both its
longitudinal ends, the VCI diffuses towards the outside of the
paperboard core 1 and acts to protect the exposed surface of the
metal coil 5 wound around the paperboard core 1 from corrosion.
[0067] The VCI becomes particularly effective when the metal coil 5
is wrapped in a packaging material 6, as illustrated in FIG. 4, so
that the paperboard core with the VCI is in the same air space as
the metal coil. Air can circulate inside the package, and the VCI
provided inside the core acts to protect the metal roll wound onto
the core 1.
[0068] The outer circumferential surface 2 of the core 1 can be
left free of any VCI chemicals, but in embodiments, the core can be
provided with a volatile corrosion inhibitor also on the outer
circumferential surface of the core. Provided that gaps exist
between the outer circumferential surface of the core and the
coiled metal sheet, air can circulate there between, and the VCI
additionally provided on the outer circumferential surface 2 of the
core 1 acts to additionally protect the metallic material roll 5
wound onto the core 1.
[0069] FIGS. 5 and 6 make it clear that there are different
possible ways of packaging a metal coil supported on a paperboard
core 1 of the present invention: according to FIG. 5, the wrapping
material is provided so as to constitute a substantially
cylindrical enclosure encompassing the metal coil and the
paperboard core, so that the metal coil and the paperboard core are
confined within the same airspace and the VCI can diffuse towards
the exposed surfaces of the metal coil. FIG. 6 shows that it would
as well be possible to have the packaging material extend into the
cavity inside the core and along the inner circumferential surface
of the core, at least about a certain distance into the core but
possibly even completely through the core. Also in this case, the
inner circumferential surface of the core and the exposed surfaces
of the metal coil are confined within the same airspace so that the
VCI on the inside of the core can protect the exposed surfaces of
the metal coil.
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