Note: Descriptions are shown in the official language in which they were submitted.
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"WINDING MANDREL FOR THE PRODUCTION OF REELS OF WEB
MATERIAL"
DESCRIPTION
Technical field
The present invention concerns the field of machines for the processing of
paper and working of web materials, in particular but not exclusively tissue
paper.
State of the art
In the production of reels of web material, in particular but not exclusively
tissue paper, expandable winding mandrels are frequently used, fitted with one
or
more cores made of cardboard or other lightweight material around which the
required quantity of web material is wound to form a log or roll. This roll,
once the
winding mandrel has been removed, can be cut into smaller rolls with shorter
axial
length for packaging and sale. In some cases, several axially aligned cores
are fitted
on the mandrel in order to simultaneously wind a plurality of rolls with axial
dimension equal to the dimension of the finished reel.
WO-03/074398 describes a machine for winding web material on winding
mandrels of the type mentioned above.
US-A-5,379,964, US-A-6,454,204, EP-A-0322864 and EP-A-0850867
describe winding mandrels made at least partly of synthetic resin reinforced
with
carbon fiber. These mandrels have mechanical locking systems operated in
various
ways. The locking elements that protrude from the mandrel to lock the winding
core
on it are controlled by internal members.
Summary of the invention
The invention relates to the production of expandable winding mandrels of
the type described above which are particularly efficient and reliable,
resistant to
wear and suitable for securely retaining and locking the winding cores during
the
winding process. According to some embodiments, the invention proposes
mandrels
which reduce the weight and rotation inertia, which provide good rigidity,
robustness
and resistance to wear, and high critical speeds.
Substantially, according to a first embodiment, a winding mandrel is provided
for the production of reels of web material with a wall made at least partly
of carbon
fibers, for example by winding continuous fibers or filaments in a resin
matrix which
then undergoes polymerization and/or crosslinking. Expandable mechanical or
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pneumatic members are provided along the mandrel wall to torsionally and
axially
lock the tubular cores on the mandrel.
In practical embodiments, according to the invention the elements that lock
the winding core on the mandrel are deformable, preferably elastically, under
the
effect of the pressure of a fluid, preferably air. In this way, when the
mandrel is not
operating, the expandable locking members are preferably fully retracted in
respective seats and do not protrude from the outer surface of the cylindrical
wall of
the mandrel. In this way said members do not interfere with insertion or
extraction of
the winding cores, reducing wear and at the same time facilitating the
insertion and
extraction operations. Under the pressure of the (liquid or gaseous) fluid the
expandable members deform, protruding from the outer cylindrical surface of
the
mandrel wall. Substantially, the deformable elements themselves, under the
pressure
of the fluid, form the member that cooperates with the core, locking it on the
mandrel. In other words, the expandable member swells due to the effect of the
fluid
under pressure and protrudes from the surface of the mandrel, pressing with a
portion
against the inner surface of the tubular winding core fitted on the mandrel.
In some embodiments the expandable members comprise a plurality of
expandable elements, preferably pneumatic, which expand radially outwards by
delivering a fluid under pressure, for example and preferably air. The fluid
under
pressure is delivered for example by means of a longitudinal duct which
extends
along at least a portion of the inner cavity of the mandrel and has a valve at
one end
of the mandrel.
In some preferred embodiments of the invention, at least one insert is
arranged along the mandrel, connected to the longitudinal duct for
distribution of the
fluid under pressure, extending inside said substantially cylindrical wall for
at least a
portion of the axial length of the mandrel. Preferably, the insert comprises
at least
one seat for an expandable pneumatic element, in fluid connection with said
longitudinal duct. Preferably several inserts are provided distributed along
the axial
length of the mandrel. In preferred embodiments of the invention, each insert
has at
least two seats and preferably three seats for respective pneumatic expandable
elements, angularly staggered with respect to one another, preferably at a
constant
angular pitch between one seat and the other.
In some preferred embodiments of the invention, the substantially cylindrical
wall is formed of a plurality of tubular portions made of carbon fiber and one
or
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more inserts; said tubular portions are interconnected by said inserts, hence
the outer
surface of the mandrel is formed partly of the inserts, which can be made of
metal,
for example a lightweight metal such as aluminum or its alloys.
In some preferred embodiments of the invention the outer surface of the
mandrel, formed of tubular portions made of carbon fiber and one or more
inserts, is
covered with a metal or ceramic coating measuring a few tenths of a millimeter
(for
example 0.3 mm). In this way it is possible to remedy problems connected with
abrasion of the core, generally made of cardboard, on the outer surface of the
mandrel. Due to the non-uniformity of the mandrel component material (fiber +
insert made of aluminum or other material), it may be necessary to resort to
an
intermediate coating made of a material that effectively "bonds" on both
materials of
the mandrel. The intermediate coating is then covered with the material which
will in
turn be ground. This solution permits trouble-free grinding of the entire
mandrel as
the mandrel is ground on a uniform material. Obviously the finished mandrel
will not
have the coating on the expandable areas (i.e. on the expandable elastic
walls). In
practice, during construction of the mandrel a "plug" can be provided on these
areas
before applying the metal/ceramic material. Subsequently the metal/ceramic
coating
is applied, the mandrel is ground and lastly the "plug" is removed, thus
obtaining a
mandrel formed of tubular carbon fiber portions and metal inserts, with a
continuous
ground metal/ceramic coating, except for the expandable areas.
Preferably, the inserts are provided with means of connection or interface to
connect the inserts to the carbon fiber tubular portions. In some embodiments
each of
said inserts can have a substantially cylindrical surface which defines, with
outer
surfaces of said carbon fiber tubular portions, the outer surface of the
mandrel.
Adjacent to said substantially cylindrical surface, frustoconical surfaces can
be
provided for connection to the tubular portions connected to the respective
insert.
The carbon fiber tubular portions will have, internally, complementary
frustoconical
surfaces thus obtaining reciprocal coupling between the inserts and the carbon
fiber
tubular portions. Alternatively, to provide the connection between the tubular
portions and the respective insert it is possible to use cylindrical surfaces
with a
grooving, for example in the order of 0.2 mm, to enhance adhesion between the
fiber
tubular portions and the inserts via the use of glue. In this configuration
there is a
negligible reduction in the resistance to force/tension transmitted between
the two
materials of the tubular portions and insert respectively during normal use of
the
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mandrel, but great construction simplification of the portion of fiber tube is
obtained
as it does not require complex machining to obtain a frustoconical form. The
tubular
portion is then fitted inside and joined by means of gluing.
Preferably the inserts comprise a central body, in which the seats for the
expandable members are provided, and axial ends each forming an interface
surface
to attach said insert to the respective tubular portions.
In some embodiments, each insert has an axial through seat, inside which a
cylindrical member is housed, provided with an axial hole through which said
longitudinal duct passes. The longitudinal duct has, at each insert, at least
one outlet
for the fluid under pressure. The cylindrical member is axially attached to
the
longitudinal duct and forms passages for supplying the fluid under pressure
coming
out of said at least one outlet towards distribution channels formed in the
insert and
in fluid communication with the expandable elements.
In some embodiments the distribution channels comprise a ring-shaped
groove and substantially radial passages extending from said ring-shaped
groove
towards said cavities containing the expandable elements.
In some embodiments the pneumatic expandable elements are formed of
volumes of fluid under pressure, at least partially delimited by a deformable
diaphragm or wall, preferably an elastically deformable one. The deformable
wall
can be made of natural or synthetic rubber, or other elastically deformable
material
having suitable characteristics of mechanical resistance and elastic
deformability.
Further possible features and embodiments of the invention are set forth in
the attached claims and will be described in greater detail below with
reference to
some embodiments.
Brief description of the drawings
The invention will be better understood by following the description and the
accompanying drawing, which shows practical non-limiting embodiments of the
invention. More specifically, in the drawing:
Fig.1 shows an axonometric view of a mandrel according to the invention in
one embodiment;
Fig.2 and 3 show longitudinal sections of the ends of the mandrel of Fig. 1;
Fig.2A and 3A show longitudinal sections of the ends of the mandrel in a
modified embodiment;
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Fig.4 shows a longitudinal section of an intermediate portion of the mandrel
of Fig.I provided with inserts comprising expandable pneumatic elements;
Fig.5 shows an enlargement of a portion of Fig.4;
Fig.5A shows an enlargement similar to that of Fig.4, with parts removed, in
5 a different embodiment;
Fig.6 is a section according to VI-VI of Fig.5;
Fig.6A is a section according to A-A of Fig.5A;
Fig.7 is a view according to VII-VII of Fig.5;
Fig.8 is an enlargement of an insert with expandable pneumatic elements in
longitudinal section in a modified embodiment of the invention;
Fig.9 is a longitudinal section of an intermediate portion of a mandrel with
the inserts of Fig.8.
Detailed disclosure of embodiments of the invention
Fig.1 shows schematically a mandrel made according to the invention and
indicated overall by the number 1. The mandrel has an intermediate part 3 and
two
end portions 5 and 7 shown in the enlargements of Fig. 2 and 3. Along the
portion 3
inserts 9 are arranged provided with expandable pneumatic elements, described
below in greater detail.
In some embodiments, the ends 5 and 7 are made of metal, for example
aluminum.
In a preferred embodiment of the invention, shown in Fig. 2A and 3A, each
of the portions 5 and 7 can in turn consist of two elements: a hollow
cylindrical pad,
fitted to the final tubular portion made of carbon fiber, and a conical end
part which
is joined to the pad by means of a coupling member, for example a pin, a
screw, a set
screw or other similar systems. In particular, Fig.3A shows the end 7 in this
embodiment. 7A indicates the hollow cylindrical pad and 7B the tapered end
part. 7C
indicates a connection screw between the parts 7A and 7B. Fig.2A shows the end
5,
limited to the hollow cylindrical pad 5A, which is provided with threaded
holes 5C
for fastening screws of a closing part not shown. The advantages of this
construction
are:
- possibility of accessing the inside of the tube also via the two ends 5 and
7
(after removal of the tapered end);
- possibility of disassembling the tapered end in the event of breakage or
failure thereof and replacing it without having to replace the entire mandrel.
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In the previous configuration the tapered end is one single piece integral
with
the tubular portion and therefore if one of the two ends 5 or 7 breaks or
fails, the
entire mandrel would have to be discarded and replaced with a new one.
The intermediate or central part 3 is made at least partly of carbon fiber in
a
polymer resin matrix.. More specifically, in the embodiment shown in Fig. 1,
with
some details thereof shown in Fig. 2 to 7, the central or intermediate part 3
of the
mandrel consists of a plurality of tubular portions 11, each of which is made
with a
wall in carbon fiber in a polymer matrix. The various tubular portions 11 are
interconnected at the inserts 9, which in this embodiment constitute not only
a
housing for the pneumatic expandable elements but also reciprocal connection
elements between the tubular portions 11 and have a substantially cylindrical
surface
which forms, together with the cylindrical surface of the tubular portions 1,
the outer
surface of the mandrel 1.
Inside the mandrel 1, and for at least one portion of its axial length, a
longitudinal duct 13 extends roughly coaxially with the cylindrical wall
defined by
the tubular portions 11 for delivery of a fluid under pressure, typically air,
to expand
the pneumatic expandable elements housed in the single inserts 9. The
longitudinal
duct 13 has a terminal valve 13A at, the end 5 of the mandrel 1, via which the
expandable pneumatic elements can be expanded or retracted by respectively
delivering a fluid under pressure, or allowing the discharge thereof.
In this embodiment each insert 9 has a structure which is described below
with reference to Fig.5 to 7. The insert has a central body 9A, in which seats
are
provided for the expandable pneumatic elements described below and from which
axial ends 9B extend forming the reciprocal connection members between insert
9
and tubular portions 11. In some embodiments, the ends 9B have frustoconical
outer
surfaces 9C defining an interface with corresponding complementary
frustoconical
surfaces 11A provided on the respective two tubular portions 11 which are
connected
to the insert 9. The frustoconical surfaces 9C have form and dimension such
that the
substantially cylindrical outer surface 11 B of each tubular portion 11 is
substantially
aligned with the outer surface 9D of the central body 9A of the insert 9 thus
forming
a substantially cylindrical continuous wall of the mandrel 1. A small ring-
shaped
groove can be maintained between the edge of each tubular portion 11 and the
central body 9A of the insert 9, as shown in the drawing.
According to some embodiments, seats (three in the example of the drawing)
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shown at 21 are provided inside the central body 9A, which house the
expandable
pneumatic elements described below, forming the torsional and axial engagement
members of the winding core with respect to the mandrel.
In the example shown, the three seats 21 are arranged angularly staggered by
a constant angle of 120 , but other arrangements are possible, for example
with a
different number of seats or with an irregular arrangement, i.e. with the
various seats
having different angular pitch.
Each seat 21 houses an expandable element 23 comprising an elastically
deformable wall, for example made of rubber and provided with a lip 23A for
anchorage and sealing inside the seat 21.
As can be seen in particular in the view of Fig.7, in plan view the expandable
element has a substantially rectangular shape elongated in the axial direction
of the
mandrel, although other shapes of the expandable element in question are not
ruled
out, for example development in a circumferential direction greater than the
development in the axial direction.
Each expandable element formed by the wall 23 is locked in the respective
seat 21 by means of a flange 25 with substantially rectangular development
(Fig.7).
Locking is obtained by means of a pair of screws 27.
A distribution channel 31 leads into each seat 21, connecting the volume
defined between the bottom of the seat 21 on one side and the deformable wall
forming the pneumatic expandable element 23 on the other with the longitudinal
duct
13. In some embodiments this connection is obtained by interposing a
cylindrical
member 33 inserted coaxially and around the longitudinal duct 13 and inside an
axial
hole 9E of the insert 9. The cylindrical member 33 has a plurality of outlets
shown at
35 for the fluid under pressure, which can be in positions angularly
corresponding to
the positions of the ducts 31. In some embodiments the outlets 35 lead at one
end
into a ring-shaped groove 37 in the axial hole of the cylindrical member 33
and on
the opposite side into a ring-shaped groove 39 provided in the inner surface
of the
hole 9E of the body 9A of the insert 9. With this arrangement, the angular
position of
the cylindrical member 33 can be made independent of the angular position of
the
seats for the pneumatic expandable elements, since the ring-shaped grooves 37
and
39 nevertheless guarantee a flow connection.
In some embodiments, the cylindrical member 33 has seal gaskets 41 and 43
between the cylindrical member 33 and the longitudinal duct 13 on the one side
and
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between the cylindrical member 33 and the inner surface of the hole 9E of the
insert
9 on the other.
In some embodiments, the cylindrical member 33 is axially secured by
forcing or other suitable manner inside the hole 9E of the body 9A of the
insert 9. In
some embodiments the cylindrical body 33 is in turn axially secured to the
longitudinal duct 13 by means of a diameter pin 45. In this way a reciprocal
positioning is obtained between the longitudinal duct 13 and the inserts 9.
This
reciprocal positioning can also be obtained with other forms of attachment
between
the parts 13, 33 and 9.
The inserts 9 are arranged in an adequate number along the axial length of the
mandrel 1, according to the longitudinal dimensions of the mandrel and other
operating requirements. In the embodiment shown, each insert 9 has three
expandable pneumatic elements arranged at 120 from one another, but as
mentioned
above, the number of the latter can vary. For example four or two of said
expandable
elements can be provided on each insert 9. The arrangement of the inserts
around the
axis of the mandrel 1 is such that the pneumatic expandable elements are
arranged in
various angular positions around the development of the mandrel thus obtaining
an
effective torsional and axial locking effect of the winding cores on the
respective
mandrel. By way of example only, Fig.5 shows a portion of a tubular core A
fitted on
the mandrel 1, which can be locked on the latter both axially and torsionally
by
introducing a fluid under pressure into the longitudinal duct 13 to cause
radial
expansion of the pneumatic expandable elements 23.
With the configuration described so far, an extremely lightweight mandrel is
obtained with a high level of rigidity due to the use of carbon fiber. Using
inserts 9
which form ring-shaped portions of the outer surface of the mandrel, and which
join
aligned tubular portions 11 made of carbon fiber, the further advantage is
achieved of
obtaining all the expandable elements and members connected therewith in an
area
which does not require any machining of the walls made of carbon fiber (a
notoriously fragile material) which form the tubular portions 11. This
guarantees a
high resistance of the mandrel by eliminating points where stress, defects and
possible delaminations of the fiber layers are concentrated.
Furthermore, the presence of the inserts 9, advantageously made of metal, for
example aluminum (at least for the body 9A and the ends 9B, while the
cylindrical
member 33 could preferably be made of plastic) makes balancing of the mandrel
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much quicker, simpler and more effective. In fact, these members must be
appropriately balanced to prevent them vibrating during use. The presence of
metal
areas distributed along the axial length of the mandrel, consisting of the
various
inserts 9, makes it possible to remove or add material, for example by
drilling the
aluminum block forming the body 9A of the single insert and if necessary
inserting
into the hole thus obtained counterweights made of different materials, with
higher
density than the aluminum.
Fig.5A and 6A show a modified embodiment, in longitudinal and cross
section respectively. These figures show only the central body of the insert
9.
Identical numbers indicate parts identical or equivalent to those of the
embodiment
example illustrated in Fig.5 and 6. The ends 9B of the body 9A have in this
case a
substantially cylindrical surface provided preferably with one or more grooves
9S
with depth of a few tenths of a millimeter, to obtain a coupling, if necessary
by
gluing, with the substantially cylindrical inner surface of the tubular
portions 11.
Fig.5A also shows a possible coating R made of ceramic and/or metal which
covers
the entire outer surface of the mandrel with the exception of the area in
which the
expandable elements are provided. This coating is applied on the fully
assembled
mandrel, completed with inner elements of the inserts 9, which are omitted
here for
the sake of clarity of the drawing. The coating can also be provided in the
remaining
embodiments.
Fig.8 and 9 show a modified embodiment of the invention. Identical numbers
indicate identical or equivalent parts with respect to those described above
with
reference to Fig.1 to 7. In this embodiment, the central part 3 of the mandrel
1 is
formed of one single tubular body or tubular portion 11 made of carbon fiber.
This tube 11 made of carbon fiber, similarly to the tubular portions 11 of the
previous embodiments, can be produced using known techniques for winding of
fibers or continuous filaments around a forming mandrel, in which the fibers
or
filaments are fed together to a polymerisable resin to form a cylindrical wall
around
the forming mandrel. The wall thus obtained subsequently undergoes
polymerisation
and/or crosslinking of the resin matrix.
Inside the cylindrical hollow body formed by the carbon fiber wall 11, a
longitudinal duct, again indicated by 13, for the delivery of a fluid under
pressure,
typically air, extends for at least a portion of the axial length of the
mandrel 1. As in
the previous example, this duct 13 has an end valve 13A for delivery of fluid
under
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pressure or for discharge of the fluid to the outside.
Along the axial length of the mandrel 1, inside the cavity 11B formed by the
carbon fiber wall 11, inserts 109 are arranged, forming housing seats for
pneumatic
expandable elements described below with particular reference to Fig.8.
5 The positioning of the inserts 109 and the axial distribution thereof along
the
mandrel 1 are chosen according to operating and construction requirements.
In some embodiments the insert 109 has a body 109A (Fig.8), in which radial
seats 121 are provided where a cylinder 122 is inserted with its axis in a
radial
direction and having channels 123 in fluid connection with the longitudinal
duct 13
10 which passes through a central diameter hole of the cylinder 122. At the
ends thereof
the cylinder 122 is attached, for example by means of two threads, to two
sleeves 125
locking respective pneumatically expandable elements 127 substantially in the
form
of a cap formed of an elastically deformable material, for example rubber.
Between
the pneumatically expandable element 127 and the respective end of the
cylinder 122
a chamber or volume 129 is defined, in which fluid under pressure can be
introduced
via the duct 123 and the duct 13. Between each sleeve 125 and the seat 121
formed
in the body 109A of the insert 109 respective gaskets 131 are arranged.
Similarly,
between the body 109A of the insert 109 and the longitudinal duct 13, which
passes
through an axial hole of the body 109A of the insert 109, further seal gaskets
133 are
arranged.
In an appropriate manner, each insert 109 is axially attached to the
longitudinal duct 13, for example via the use of a respective diameter pin 135
or set
screws or other equivalent means.
As shown in particular in Fig.8, each expandable element 127 is housed at
least partially inside a respective hole 11 F provided in the cylindrical wall
11 made
of carbon fiber. This embodiment, therefore, requires machining by drilling of
the
carbon fiber component 11 forming the central or intermediate part 3 of the
mandrel
1, with consequent formation of stress concentration areas along the mandrel
wall.
Furthermore, balancing of the mandrel is more difficult due to the lack of
metal
surfaces accessible from the outside which can be machined to lighten the
component.
The operation of the mandrel in this embodiment can be easily understood
from the above description. The core A (shown partially in Fig.8) is
torsionally and
axially locked on the mandrel by expansion of the individual pneumatic
expandable
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elements 127 due to the delivery of a fluid under pressure, typically air,
through the
longitudinal duct 13 and the radial ducts 123. The core is released by
discharging the
pressure from these ducts.
It is understood that the drawing only shows one example provided as a
practical demonstration of the invention, which can vary in the forms and
arrangements without departing from the scope of the concept underlying the
invention. Any reference numbers in the attached claims are provided to
facilitate
reading of the claims with reference to the description and the drawing, and
do not
limit the protective scope of the claims.
