U.S. patent application number 11/448668 was filed with the patent office on 2006-12-28 for aquatic gliding board having a deck with a sandwich structure with an elastic core.
This patent application is currently assigned to SALOMON S.A.. Invention is credited to Anthony Bert.
Application Number | 20060292941 11/448668 |
Document ID | / |
Family ID | 35789301 |
Filed Date | 2006-12-28 |
United States Patent
Application |
20060292941 |
Kind Code |
A1 |
Bert; Anthony |
December 28, 2006 |
Aquatic gliding board having a deck with a sandwich structure with
an elastic core
Abstract
An aquatic gliding board, or float, which includes a core
covered with an outer casing forming a deck and a hull thereof. The
outer-casing includes at least one deck portion and one hull
portion, at least the deck portion of the casing having a sandwich
structure which includes at least one low-density core between two
thinner layers having high mechanical characteristics including
layers of resin-impregnated fibers, with the low-density core of
the sandwich structure of the casing of the deck portion including
a flexible and elastic cellular material.
Inventors: |
Bert; Anthony; (Annecy,
FR) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
SALOMON S.A.
Metz-Tessy
FR
|
Family ID: |
35789301 |
Appl. No.: |
11/448668 |
Filed: |
June 8, 2006 |
Current U.S.
Class: |
441/65 |
Current CPC
Class: |
B63B 32/57 20200201 |
Class at
Publication: |
441/065 |
International
Class: |
B63B 1/00 20060101
B63B001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 9, 2005 |
FR |
05.05875 |
Claims
1. An aquatic gliding board comprising: a core; an outer casing
covering the core, said outer casing comprising: a deck portion;
and a hull portion; at least the deck portion of the outer casing
comprising a sandwich structure, said sandwich structure
comprising. at least one low-density core layer between two thinner
layers; the low-density core layer of the sandwich structure
comprising a flexible and elastic cellular material; each of the
two thinner layers having a higher strength and stiffness than the
core layer of the sandwich structure; each of the two thinner
layers comprising a layer of resin-impregnated fibers.
2. An aquatic gliding board according to claim 1, wherein: the
low-density core layer of the sandwich structure of the deck
portion of the outer casing comprises a polyolefin foam.
3. An aquatic gliding board according to claim 2, wherein: the
low-density core layer of the sandwich structure of the deck
portion of the outer casing comprises a polypropylene foam.
4. An aquatic gliding board according to claim 1, wherein: the
material of the low-density core layer of the sandwich structure of
the deck portion of the outer casing has a 25% compressive
deformation stress, ranging from 100 to 600 kPa.
5. An aquatic gliding board according to claim 1, wherein: the
material of the low-density core layer of the sandwich structure of
the deck portion of the outer casing has an elastic deformation
recovery capacity such that initial shape of the material is
recovered following a compression of 25% or about 25%.
6. An aquatic gliding board according to claim 1, wherein: the
sandwich structure of the deck portion of the outer casing extends
downwardly along lateral sides of the aquatic gliding board.
7. An aquatic gliding board according to claim 1, wherein: the
sandwich structure of the deck portion of the outer casing is
covered with a protective layer made of thermoformed plastic
material.
8. An aquatic gliding board according to claim 7, wherein: the
protective layer is transparent; and an inner surface of the
protective layer includes a decoration.
9. An aquatic gliding board according to claim 1, wherein: the hull
portion of the outer casing comprises a sandwich structure, said
sandwich structure comprising: at least one low-density core layer
between two thinner layers; the low-density core layer of the
sandwich structure of the hull portion of the outer casing
comprises a rigid material; each of the two thinner layers of the
sandwich structure of the hull portion of the outer casing having a
higher strength and stiffness than the core layer of the sandwich
structure of the hull portion of the outer casing; each of the two
thinner layers of the sandwich structure of the hull portion of the
outer casing comprising a layer of resin-impregnated fibers.
10. An aquatic gliding board according to claim 1, wherein: the
hull portion of the outer casing comprises at least one layer of
resin-impregnated fibers, said at least one layer of
resin-impregnated fibers covering an intermediate layer of rigid
material.
11. An aquatic gliding board according to claim 1, wherein: the
core of the aquatic gliding board is made of expanded polystyrene
foam.
12. An aquatic gliding board according to claim 1, wherein: the
core of the aquatic gliding board comprises recesses.
13. An aquatic gliding board according to claim 1, further
comprising: a protective layer made of thermoformed plastic
material covering an entirety of the aquatic gliding board.
14. An aquatic gliding board according to claim 12, wherein: the
protective layer is transparent; and an inner surface of the
protective layer includes a decoration.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.119
of French Patent Application No. 05.05875, filed on Jun. 9, 2005,
the disclosure of which is hereby incorporated by reference thereto
in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to the field of aquatic gliding
boards, or floats, such as surfboards of boards for
windsurfing.
[0004] 2. Description of Background and Relevant Information
[0005] Conventionally, a surfboard and other types of aquatic
boards or floats are made from a block of foam, such as a rigid
polyurethane foam blank that is formed in a mold. The foam blank is
machined by planing and sanding in order to locally customize its
shape and thereby form the core of the float/board. This machined
core is then covered with a resin-impregnated glass fiber layer
that forms an outer reinforcement shell and gives the board its
final shape and its mechanical strength. A decoration and a glaze
coating give the board its final appearance.
[0006] In some cases, the core is longitudinally cut into two
portions, which are then glued to a wood stringer which reinforces
the structure of the core.
[0007] One of the drawbacks of this conventional construction
method is the final weight of the finished board. Indeed, the foam
is relatively dense: typically, its bulk density is about 50
kg/m.sup.3, and it is, a priori, not possible to reduce the foam
density without negatively affecting the mechanical properties of
the board.
[0008] In the field of "bodyboards," the float is mainly made of
elastic foam (such as by associating several layers having various
densities and characteristics) without having an outer casing with
high mechanical characteristics. In some cases, such floats are
provided with a lower thermoformed plastic layer to ensure better
gliding on water. However, these boards are generally relatively
flexible as the user must be able to deform them during use for
better maneuvering. Unlike boards for surfing and windsurfing, on
which the user stands, bodyboards are not required to withstand
substantial forces because the user operates such a board while
lying down facing the water surface with only his/her torso
supported on the board.
[0009] According to another method of construction originating from
the field of windsurfing and sailboards, one starts with a rigid
foam blank with a relatively low density (for example an 18
kg/m.sup.3 expanded polystyrene foam), which is machined to shape,
or molded directly to the shape of the core of the float/board. The
core is covered with an outer layer, or casing, which can take the
form of a resin-impregnated glass fiber skin, and/or a sheet of
thermoformed plastic material, and/or a sandwich structure. Such a
construction method can allow for more weight while maintaining a
good rigidity, especially when a sandwich structure casing is used,
that is, a structure including a low-density layer (generally a PVC
or an extruded polystyrene foam) located between two thinner layers
having high mechanical characteristics (such as resin-impregnated
fiber). Such a construction, when using sandwich structures,
enables one to achieve rigid, and therefore potentially efficient
boards, but sometimes at the expense of comfort and
maneuverability.
[0010] According to other techniques, a gliding board can be
constructed to include a central core made of a first cellular
material covered by a layer of rigid, more dense and stronger
cellular material, itself covered by an outer skin, such as a
thermoformed plastic sheet or resin-coated layer of fibers, as
disclosed in the patent documents WO 82/04023 and DE 33 11 734.
[0011] It is also known to make hollow gliding boards having a
sandwich structured casing. For example, two half-shells can be
made, which are then assembled to one another, or, alternatively,
the entirety is made in a closed mold having an inner bladder that
is inflated to push and apply the sandwich structure against the
walls of the mold.
[0012] It is also known to make gliding boards that include a rigid
inner structure covered by an outer layer of flexible foam, which
determines the outer form of the board, as disclosed in U.S. Pat.
No. 3,543,315 and U.S. Pat. No. 5,489,228. These boards are
generally very comfortable during navigation, but they are too
heavy and the flexibility of their outer casing does not yield good
results in terms of responsiveness and steering accuracy of the
board. Indeed, the layer of flexible foam is only covered by a
plastic film or a flexible casing having no notable mechanical
strength, the only role of which is to protect the flexible foam
from abrasion and to improve gliding.
[0013] In addition, gliding boards have been proposed which have a
different hull and deck structure. The patent document FR 2 787 088
provides for a gliding board that includes a foam core covered by a
casing. On the deck, the casing is a rigid sandwich structure,
whereas for the hull, the casing is a mere layer of
resin-impregnated fibers. In the patent document FR 2 612 874, the
hull of the board is covered with a thin layer of elastic material
so as to give it shock-absorbing properties. Conversely, in the
patent document DE 32 06 334, it is the deck of the board that is
covered with a layer of elastic material. In the two latter cases,
the layers of elastic material are directly exposed to the
outside.
[0014] The patent document DE 197 41 917 discloses a plurality of
constructions in which the casing of the board has a layer of
resin-impregnated fiber associated with a layer of damping
material. Various options are provided, but it is always provided
for the damping layer to be arranged on the outside with respect to
the layer of resin-impregnated fibers. However, the damping layer
is provided to be located either solely on the deck, or on the deck
and on the hull of the board. This document does not envision using
a sandwich structured casing.
SUMMARY OF THE INVENTION
[0015] The invention provides for an aquatic gliding board, or
float, which includes a core covered by an outer casing forming a
deck and a hull for the board, in which at least the deck portion
of the casing having a sandwich structure including at least a
low-density central layer between two thinner layers with high
mechanical characteristics, in which the high mechanical
performance layers include layers of resin-impregnated fibers, and
in which the central, low-density layer of the sandwich structure
of the deck portion includes a flexible and elastic cellular
material.
[0016] In a particular exemplary embodiment, the aquatic gliding
board of the invention includes a core covered with an outer casing
forming a deck and a hull, in which the outer casing includes at
least a deck portion and a hull portion, both made in the form of a
sandwich structure made, for each of the portions, of at least one
low-density central layer between two thinner layers having high
mechanical characteristics, in which such high mechanical
performance layers include layers of resin-impregnated fiber, in
which the low density central layer of the hull portion is made out
of rigid cellular material, and in which the low-density central
layer of the deck portion includes a flexible and elastic cellular
material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Other characteristics and advantages of the invention will
become apparent upon reading the following description, with
reference to the attached drawings, and in which:
[0018] FIG. 1 is a top schematic view of a float/board according to
a particular exemplary embodiment of the invention;
[0019] FIG. 2 is a cross-sectional schematic view along the line
II-II of the of FIG. 1;
[0020] FIG. 3 is an enlarged and exploded partial view of FIG.
2;
[0021] FIG. 4 is a cross-sectional partially cut-away schematic
view showing an embodiment for a stiffening reinforcement.
DETAILED DESCRIPTION OF THE INVENTION
[0022] FIG. 1 shows the general outer form of a float 10 for
gliding on water, such as a surfboard or a sailboard, for example.
Hereinafter, the float will be referred to as a board or a gliding
board. FIG. 2 shows an embodiment of the invention in which the
board includes a core 14 arranged inside an outer casing 12. In a
known manner, the upper portion of the outer casing 12 forms the
deck 16 of the board adapted to support the user, and in its lower
portion, the hull 18 faces the water. The peripheral lateral
surface/edge of the outer casing defines the rails of the board.
This outer casing defines, in a watertight manner, an inner space
of the board that is entirely or partially filled by the core.
[0023] The core can be made, as one example encompassed by the
invention, using an expanded polystyrene foam having very low
density, for example, a bulk density lower than 25 kg/m.sup.3, or
even equal to or lower than 18 kg/m.sup.3.
[0024] The core 14 can also include localized reinforcements, made
out of a particularly strong material, which extend along the
entire height of the inner space demarcated by the casing, or along
only a portion of this height. An example of such a core is
described hereinafter, with reference to FIG. 4.
[0025] In the example shown, the core 14 entirely fills up the
inner space of the board. However, it could also be provided that
recesses be included so as to leave hollow inner zones inside the
outer casing 12, for example, at the front of the board, which is a
zone on which the user generally applies very little force since
the surfer typically does not apply his/her weight to the front
zone. The presence of hollow zones favorably reduces the weight of
the board, and their distribution affects the dynamic moment of
inertia of the board, which influences its behavior on water,
particularly its responsiveness to the various forces and changes
of direction applied by the user.
[0026] Out of simplicity and cost-efficiency, the exemplary core 14
shown in the drawing figures is a unitary element made out of a
single material. However, the core could be made from a plurality
of elements, possibly made of various materials.
[0027] In addition, the core could be made to include a plurality
of holes or recesses to lighten the core. Similar methods to
lighten the core, such as those described in patent documents FR 2
820 712, FR 2 820 713, and FR 2 820 714, could be advantageously
implemented and, therefore, are encompassed by the invention.
[0028] In this embodiment of the invention, the two portions (deck
and hull) of the casing have a sandwich construction in which a
layer of low-density material forming the core 24, 25 of the
sandwich structure is confined between an inner layer 26 and an
outer layer 28 of reinforcement material that form the skins of the
sandwich and include, for example, layers of fiber embedded in
resin, for example epoxy resin. The type of fibers (glass, carbon,
aramid, etc.) can be identical or different for the inner and outer
layers. Similarly, it can differ between the hull portion and the
deck portion, meaning, for example, that one can provide for the
inner layer of the deck to include aramid fibers, whereas the inner
layer of the hull would include carbon fibers. In the same way, the
layers of fibers can be woven or non-woven, unidirectional or
multidirectional. For the simplest and most cost-effective
constructions, the layers of fibers are glass fiber fabrics.
[0029] However, in this particular exemplary embodiment of the
invention, the deck and hull portions of the casing differ in the
type of material of which the core 24, 25 of their sandwich
structure is constituted. In the hull portion, the low-density
material layer 25 is made of one or several materials referred to
as "rigid", whereas in the deck portion, the low-density material
layer 24 includes, according to the invention, at least one portion
made of a flexible cellular material. In relative terms, of course,
the material(s) of layer 25 are more rigid than the material(s) of
flexible layer 24, and the material(s) of layer 24 are more
flexible than the material(s) of rigid layer 25.
[0030] In particular exemplary embodiments of the invention, the
low-density materials are cellular materials, such as foams made of
plastic materials.
[0031] One having ordinary skill in the art usually classifies
plastic material foams as flexible foams, on the one hand, and as
rigid foams, on the other hand.
[0032] The rigid foams have low elasticity in the sense that as
soon as the compression force exceeds a certain value, they deform
by collapsing in an irreversible manner, or only a slightly
reversible manner. Examples of rigid foams are polyurethane foams
and extruded polystyrene foams or expanded polystyrene foams, which
are generally used in the form of foam blanks to form the cores of
conventional surfboards. Similarly, some PVC or polyimide foams,
generally used as cores in sandwich structures, are considered as
rigid materials. Although referred to as rigid, these foams, in the
lowest densities, can be quite easily compressed (and can therefore
appear to be soft), yet they have very low elasticity.
[0033] Flexible foams made of plastic material having elastic
properties, such as expanded polyolefin foams, particularly
polypropylene and polyethylene foams, are among those known as
flexible cellular materials. In the case of expanded polypropylene
foams, grades having bulk densities between 20 and 100 kg/m.sup.3,
for example, can be used These materials generally have a 25%
compressive deformation stress, ranging from 100 to 600 kPa.
Considerations in choosing a material are its compressive strength,
but even more so, its capacity to deform elastically (the material
will preferably recover its initial shape after a compression of
25% or about 25%), and its capacity for restoring the energy
absorbed during the compression.
[0034] In addition to the foregoing, the invention encompasses the
use of other materials. In this regard, for the hull, the rigid
foam 25 can be replaced by a honeycomb structure, or by a layer of
wood, such as a light-weight wood.
[0035] Using a rigid core 25 for the sandwich structure of the hull
makes it possible to achieve a substantial rigidity for the hull,
which promotes good acceleration capabilities and a very precise
steering of the board. In less elaborate alternative embodiments of
the invention, the hull portion of the casing can have another
structure. For example, the hull can be a mere layer of
resin-impregnated fibers, or an intermediate layer of a light and
rigid material (rigid foam, light wood, etc.) covered with a layer
of resin-impregnated fibers.
[0036] The use of a flexible material to form the core 24 of the
sandwich structure of the deck is particularly innovative. Indeed,
by choosing the right rigidity for this flexible material, one can
take advantage of the exceptional rigidity-to-weight ratio of the
sandwich structure while inserting, in the area of the deck, a
surface flexibility that is particularly advantageous in terms of
comfort and ease of steering the board.
[0037] This is due to the fact that the outer skin 28 of
resin-impregnated fibers, which intrinsically has high elastic
properties, can deform under the forces applied by the user without
causing the collapse of the core material 24, which is also
elastic, and then return to its original position while restoring a
major portion of the stored energy. The outer skin 28 is then
biased both in flexion and traction, along its surface, like a
trampoline. Thus biased, the outer skin 28 made of composite
material, allows for restoring much more energy than the mere
elastic return of a plastic material, which would be arranged on
the deck of the float and which would be vertically compressed. By
comparison, the "trampoline" effect with a high elastic component
can be opposed to a mere "mattress" effect that is mainly damping,
and which therefore tends to restore only a small portion of the
energy that is transmitted to it. The trampoline effect makes
steering the float much more lively.
[0038] This deformation/restitution effect of the outer skin 28 of
the sandwich is completely reversible (at least up to a certain
limit that can be determined, for example, by varying the thickness
and the rigidity of the outer skin 28 and/or by varying the
rigidity of the flexible elastic material forming the core 24 of
the sandwich structure), and it occurs without causing any notable
deformation of the core 14, due to the presence of the layer 26 of
resin-impregnated fibers under the flexible and elastic layer. The
layer of resin-impregnated fibers, in addition to its own
mechanical strength, makes it possible to distribute the stress
transmitted thereto over a large surface.
[0039] In addition to the advantage in terms of vivacity, or
liveliness, the sandwich construction with elastic core enables the
deck to better withstand impacts and caving-in effects. To improve
the trampoline effect, the resin of the outer skin (for example an
epoxy resin) can possibly be mixed with compounds that improve its
flexibility.
[0040] It can be seen from the example shown that the layer of
flexible foam 24 that forms the core of the sandwich structure of
the deck extends downwardly along the lateral edges of the board.
This especially makes it possible to take advantage of the better
impact resistance of this structure in a particularly exposed zone.
One could provide for the sandwich structure 25 of the hull of the
float to rise along the lateral edges, for the two structures to
meet at the widest point, or for the lateral edges to have their
own structure.
[0041] Various methods for manufacturing a board according to the
invention are encompassed by the invention.
[0042] The outer casing 12 can be manufactured in the form of two
prefabricated half-shells forming the deck and the hull,
respectively, of the board, the half-shells being assembled to one
another, for example by gluing, along their parting line, to form a
watertight outer casing.
[0043] In an alternative embodiment, the two half-shells can be
assembled one to the other before the reinforcement outer layer is
applied on the layer forming the core of the sandwich. Such a
method is similar to that described in the patent document WO
02./10011 and family member U.S. Pat. No. 6,736,689, the disclosure
of the latter of which is hereby incorporated by reference thereto
in its entirety, and which advantageously provides an opportunity
to rework the layer forming the core of the sandwich after
assembling the half-shells, but before applying the outer layers of
the sandwich, in order to customize the shape of the board, if
desired.
[0044] According to another method of construction, all of the
components can be assembled and shaped under pressure in a mold,
according to the technique usually used for the manufacture of
windsurfing boards of the sandwich type.
[0045] In the example shown in the drawings (see, e.g., FIG. 3), it
has been provided for the outer casing 12 to further include an
outer protection made in the form of a sheet 30 of thermoformed
thermoplastic material. This protective layer 30 is translucent,
for example, and can be decorated. The decoration can
advantageously be arranged on the side of the sheet that is turned
toward the inside, and can be made, for example, by silk-screening
or by sublimation. Also a decoration element can be incorporated
between the outer skin 28 and the protective sheet. The protective
sheet can be made out of a material including a mixture of ABS and
polyurethane, for example, and have a thickness of about 0.3 mm.
The protective sheets could possibly be different on the deck and
on the hull of the board. Such a protection layer be arranged on
only one side of the board, for example on the deck.
[0046] FIG. 4 shows an embodiment of a reinforcement 32. This
reinforcement 32 is simply made of a sheet of resin-impregnated
fibers folded over itself to form a T-shape, the vertical arm 34 of
which is inserted in a groove 36 formed in the core 14, and the
horizontal portion 38 of which rests against an upper surface of
the core 14. To this end, a rectilinear groove 36 substantially
perpendicular to the outer surface of the core is arranged in the
core. The sheet of resin-impregnated fibers (not yet polymerized
and therefore still flexible), is folded over in two and inserted
at the hull of the groove 36. The portions of the sheet which
project outwardly are then folded back against the outer surface of
the core. Once the resin has been polymerized, the reinforcement 32
forms a rigid T-shaped profile, which is integrated into the core
14. The vertical portion 34 of the T-shape gives it a very good
flexural strength, whereas the horizontal portion 38 forms a kind
of plate that allows the distribution of the pressures exerted
locally by the outer casing 12 on the core 14. Thus, this
reinforcement 32 is particularly advantageously placed on the
board's deck as it reinforces the core where the strong pressures
applied by the user are exerted. FIG. 1 shows a possible
arrangement with two reinforcements 32 arranged on the deck, on
each side of a median longitudinal axis of the board. A
reinforcement of this type could also be used on the hull of the
board to take full advantage of its flexural strength.
[0047] In the example of FIG. 4, the reinforcement 32 is positioned
on the exposed core 14. However, to facilitate this operation, the
reinforcement could be positioned after having coated the core with
the inner skin 26. The main difference is that the horizontal
portion 38 of the T-shape of the reinforcement is then arranged
between the inner skin 26 and the low-density layer 24, 25.
[0048] The construction according to the invention therefore
provides for the manufacture of an aquatic board, such as a
surfboard or sailboard, which offers a perfect compromise between
ease and steering precision, comfort and performance, all of which
are achieved with a method of construction well-suited for
industrial implementation, allowing relatively low production
costs.
[0049] Moreover, based upon the foregoing description, the
invention provides for a new optimized construction for the
manufacture of an aquatic gliding board, such as a surfboard or a
tailboard, which enables an easy and low-cost implementation, a
limited final weight for the board, while achieving a sufficient
overall stiffness for good performance, as well as a guaranteed
comfort of use, without sacrificing either steering precision or
structural integrity.
* * * * *