U.S. patent application number 13/261169 was filed with the patent office on 2012-07-05 for winding mandrel for the production of reels of web material.
This patent application is currently assigned to FABIO PERINI S.p.P.. Invention is credited to Daniele Dettori, Tiziano Fracassi, Mauro Gelli.
Application Number | 20120168553 13/261169 |
Document ID | / |
Family ID | 42008563 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120168553 |
Kind Code |
A1 |
Gelli; Mauro ; et
al. |
July 5, 2012 |
WINDING MANDREL FOR THE PRODUCTION OF REELS OF WEB MATERIAL
Abstract
The winding mandrel includes a substantially cylindrical wall
with expandable members for the torsional locking of tubular
winding cores. At least one portion of the wall is made of carbon
fiber in a polymer resin matrix.
Inventors: |
Gelli; Mauro; (Capannori
(LU), IT) ; Fracassi; Tiziano; (Lammari (LU), IT)
; Dettori; Daniele; (Capannori (LU), IT) |
Assignee: |
FABIO PERINI S.p.P.
Lucca
IT
|
Family ID: |
42008563 |
Appl. No.: |
13/261169 |
Filed: |
July 27, 2010 |
PCT Filed: |
July 27, 2010 |
PCT NO: |
PCT/IT2010/000336 |
371 Date: |
March 6, 2012 |
Current U.S.
Class: |
242/571.2 |
Current CPC
Class: |
B65H 75/242
20130101 |
Class at
Publication: |
242/571.2 |
International
Class: |
B65H 75/24 20060101
B65H075/24 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2009 |
IT |
FI2009A000176 |
Claims
1-23. (canceled)
24. A winding mandrel for producing reels of web material,
comprising a substantially cylindrical wall with expandable members
for torsionally locking tubular winding cores on said mandrel,
wherein at least a portion of said wall is made of carbon fibers in
a polymer resin matrix; said expandable members include a plurality
of expandable elements that expand radially outwards of said
substantially cylindrical wall by delivery of a fluid under
pressure thereto; a plurality of inserts are provided along an
axial length of the mandrel, said inserts being connected to a
longitudinal duct for the distribution of the fluid under pressure,
wherein said duct extends inside said substantially cylindrical
wall for at least a part of the axial length of the mandrel; and
each of said inserts comprises at least one seat for an expandable
element, in fluid connection with said longitudinal duct.
25. The winding mandrel according to claim 24, wherein said
expandable elements are pneumatic expandable elements.
26. The winding mandrel according to claim 25, wherein said fluid
under pressure is air.
27. The winding mandrel according to claim 24, wherein said
expandable elements are deformable due to said delivery of said
fluid under pressure so as to protrude from said substantially
cylindrical wall; and wherein in absence of said fluid under
pressure, said expandable elements are entirely retracted in
respective seats so as to not protrude from an outer surface of
said substantially cylindrical wall.
28. The winding mandrel according to claim 24, wherein each of said
inserts includes at least two seats for corresponding expandable
elements arranged in angularly staggered positions around an axis
of the mandrel.
29. The winding mandrel according to claim 24, wherein the
substantially cylindrical wall is composed of a plurality of
tubular portions made of carbon fibers in a polymer resin matrix,
and of one or more of said inserts; said tubular portions being
connected to one another by said inserts.
30. The winding mandrel according to claim 29, wherein each of said
inserts has a substantially cylindrical surface that defines,
together with outer surfaces of said carbon fiber tubular portions,
a substantially cylindrical surface.
31. The winding mandrel according to claim 30, wherein said
substantially cylindrical surface has a substantially continuous
coating.
32. The mandrel according to claim 31, wherein said coating
comprises at least one layer comprising metal or ceramic.
33. The winding mandrel according to claim 29, wherein each of said
inserts includes a central body containing said at least one seat
for the expandable elements and axial ends which each form an
interfacing surface for attaching said inserts to respective
tubular portions.
34. The winding mandrel according to claim 33, wherein said axial
ends have an outer surface which is tapered or cylindrical, said
outer surface being grooved for anchorage of the tubular
portions.
35. The winding mandrel according to claim 33, wherein said central
body has a substantially cylindrical outer surface provided with
cavities for housing said expandable elements.
36. The expandable mandrel according to claim 24, wherein each of
said inserts has an axial through cavity in which a cylindrical
member is contained, with an axial hole for passage of said
longitudinal duct; coinciding with each of said inserts, said
longitudinal duct has at least one outlet for the fluid under
pressure; and said cylindrical member is axially attached to the
longitudinal duct, forming passages for the delivery of the fluid
under pressure coming from said at least one outlet into
distribution channels formed in said inserts and in fluid
connection with said expandable elements.
37. The expandable mandrel according to claim 35, wherein each of
said inserts has an axial through cavity in which a cylindrical
member is contained, with an axial hole for passage of said
longitudinal duct; coinciding with each of said inserts, said
longitudinal duct has at least one outlet for the fluid under
pressure; and said cylindrical member is axially attached to the
longitudinal duct, forming passages for the delivery of the fluid
under pressure coming from said at least one outlet into
distribution channels formed in said inserts and in fluid
connection with said expandable elements; and said distribution
channels comprise a ring-shaped groove and substantially radial
passages extending from said ring-shaped groove towards said
cavities for housing the expandable elements.
38. The winding mandrel according to claim 24, wherein said
expandable elements are formed by volumes of fluid under pressure
at least partially contained by a deformable diaphragm.
39. The mandrel according to claim 38, wherein said deformable
diaphragm is made of an elastic material.
40. The winding mandrel according to claim 35, wherein each of said
cavities for each of said inserts contains an expandable element
comprising an elastically deformable wall with an anchorage and
sealing lip, fixed in a respective one of said cavities by a
locking flange that retains said anchorage and sealing lip inside a
groove provided in a corresponding cavity.
41. The winding mandrel according to claim 24, wherein said
expandable elements are housed inside corresponding radial holes
provided in the substantially cylindrical wall made of carbon
fibers in a polymer resin matrix and defining said substantially
cylindrical wall of the mandrel.
42. The winding mandrel according to claim 24 comprising metal
terminal ends, at least one of said metal terminal ends being
associated with means for activating the expandable members.
43. The winding mandrel according to claim 42, wherein at least one
of said metal terminal ends is made in two parts, a first part
attached irreversibly to the mandrel with a hollow body to allow
access to inside of the mandrel, and a second part removably
attached to said first part.
44. The winding mandrel according to claim 24, wherein said inserts
are made of a metallic material.
Description
TECHNICAL FIELD
[0001] 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
[0002] 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.
[0003] WO-03/074398 describes a machine for winding web material on
winding mandrels of the type mentioned above.
[0004] U.S. Pat. No. 5,379,964, U.S. Pat. No. 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
[0005] 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.
[0006] 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 pneumatic members are provided along the mandrel wall to
torsionally and axially lock the tubular cores on the mandrel.
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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 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.
[0011] 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.
[0012] 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 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.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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
[0018] 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:
[0019] FIG. 1 shows an axonometric view of a mandrel according to
the invention in one embodiment;
[0020] FIGS. 2 and 3 show longitudinal sections of the ends of the
mandrel of FIG. 1;
[0021] FIGS. 2A and 3A show longitudinal sections of the ends of
the mandrel in a modified embodiment;
[0022] FIG. 4 shows a longitudinal section of an intermediate
portion of the mandrel of FIG. 1 provided with inserts comprising
expandable pneumatic elements;
[0023] FIG. 5 shows an enlargement of a portion of FIG. 4;
[0024] FIG. 5A shows an enlargement similar to that of FIG. 4, with
parts removed, in a different embodiment;
[0025] FIG. 6 is a section according to VI-VI of FIG. 5;
[0026] FIG. 6A is a section according to A-A of FIG. 5A;
[0027] FIG. 7 is a view according to VII-VII of FIG. 5;
[0028] FIG. 8 is an enlargement of an insert with expandable
pneumatic elements in longitudinal section in a modified embodiment
of the invention;
[0029] 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
[0030] 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 FIGS. 2 and 3. Along the portion 3 inserts 9 are
arranged provided with expandable pneumatic elements, described
below in greater detail.
[0031] In some embodiments, the ends 5 and 7 are made of metal, for
example aluminum.
[0032] In a preferred embodiment of the invention, shown in FIGS.
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: [0033] possibility of
accessing the inside of the tube also via the two ends 5 and 7
(after removal of the tapered end); [0034] possibility of
disassembling the tapered end in the event of breakage or failure
thereof and replacing it without having to replace the entire
mandrel.
[0035] 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.
[0036] 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
FIGS. 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.
[0037] 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.
[0038] 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 11B 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.
[0039] According to some embodiments, seats (three in the example
of the drawing) 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.
[0040] In the example shown, the three seats 21 are arranged
angularly staggered by a constant angle of 120.degree., 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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 between the cylindrical
member 33 and the inner surface of the hole 9E of the insert 9 on
the other.
[0046] 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.
[0047] 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.degree. 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.
[0048] 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.
[0049] 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 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.
[0050] FIGS. 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 FIGS.
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.
[0051] FIGS. 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.
[0052] 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 pressure or for discharge of the fluid to the
outside.
[0053] 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. The positioning of the
inserts 109 and the axial distribution thereof along the mandrel 1
are chosen according to operating and construction
requirements.
[0054] 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 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.
[0055] 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.
[0056] As shown in particular in FIG. 8, each expandable element
127 is housed at least partially inside a respective hole 11F
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.
[0057] 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
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.
[0058] 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.
* * * * *