U.S. patent application number 14/112767 was filed with the patent office on 2014-02-06 for next-generation wooden racket.
This patent application is currently assigned to Lacoste. The applicant listed for this patent is Alain Gallais, Alain Zanco. Invention is credited to Alain Gallais, Alain Zanco.
Application Number | 20140038754 14/112767 |
Document ID | / |
Family ID | 46146936 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140038754 |
Kind Code |
A1 |
Gallais; Alain ; et
al. |
February 6, 2014 |
Next-Generation Wooden Racket
Abstract
The invention relates to a tennis racket including a frame,
delimiting a surface strung with cords and forming a screen, and a
sleeve extending the frame outside the screen, characterized in
that the frame consists of, at least within a peripheral region, a
curved laminate comprising at least two layers of different
materials adhered together, the laminate being shaped such that, in
a closed cross-section of said peripheral region considered to be
perpendicular to the neutral fiber of the frame, the center of mass
of said cross-section is offset, relative to the surface center of
gravity of said cross-section, toward the screen with a value at
least equal to 5% of the width of said cross-section, said width
being defined by the intersection of the cross-section and the
plane of the screen.
Inventors: |
Gallais; Alain; (Paris,
FR) ; Zanco; Alain; (Grand Coeur, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gallais; Alain
Zanco; Alain |
Paris
Grand Coeur |
|
FR
FR |
|
|
Assignee: |
Lacoste
Paris
FR
|
Family ID: |
46146936 |
Appl. No.: |
14/112767 |
Filed: |
April 19, 2012 |
PCT Filed: |
April 19, 2012 |
PCT NO: |
PCT/FR2012/050855 |
371 Date: |
October 18, 2013 |
Current U.S.
Class: |
473/526 |
Current CPC
Class: |
A63B 49/02 20130101;
A63B 60/02 20151001; A63B 2209/00 20130101; A63B 2209/02 20130101;
A63B 2049/0202 20151001 |
Class at
Publication: |
473/526 |
International
Class: |
A63B 49/02 20060101
A63B049/02 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 20, 2011 |
FR |
1153422 |
Claims
1. Racket for ball games, particularly tennis, comprising a frame
delimiting a strung surface forming a mesh, a handle extending the
frame outside the mesh, characterised in that the frame is formed,
at least in a peripheral region, from a bent lamination of at least
two layers of different materials placed adjacent to each other,
the lamination being shaped so that, in a closed cross-section of
said peripheral region, considered perpendicular to the neutral
axis of the frame, the centre of mass of said cross-section is
offset towards the mesh relative to the centre of area of said
cross-section, by a value of at least 5% of the width of said
cross-section, said width being defined by the intersection of the
cross-section with the plane of the mesh.
2. Racket according to claim 1, characterised in that the frame is
formed from a lamination comprising at least two layers of
different materials, a first layer of which, located on the inner
side of the frame, has a greater density than the second layer,
located on the outer side of the frame.
3. Racket according to claim 1, characterised in that the
lamination is formed from at least three layers of at least two
different materials.
4. Racket according to claim 1, characterised in that the
lamination is formed from at least four layers of at least three
different materials.
5. Racket according to claim 1, characterised in that the
lamination comprises several layers of different types of wood,
said types of wood being selected from acacia, balsa, walnut.
6. Racket according to claim 5, characterised in that the
lamination comprises at least one acacia layer located on the inner
side of the frame and delimiting the mesh.
7. Racket according to claim 5, characterised in that said at least
one acacia layer is formed from two acacia layers arranged so that
the respective fibres thereof are in opposite directions to each
other.
8. Racket according to claim 5, characterised in that the
lamination comprises at least one walnut layer located on the
outside of the frame.
9. Racket according to claim 5, characterised in that the
lamination comprises at least one balsa layer.
10. Racket according to claim 9, characterised in that said at
least one balsa layer is inserted between said at least one acacia
layer and said at least one walnut layer.
11. Racket according to claim 9, characterised in that said at
least one balsa layer is encased in a fibreglass sheath.
12. Racket according to claim 11, characterised in that the
fibreglass sheath comprises a reinforcement selected from carbon
threads or basalt threads.
13. Racket according to claim 1, characterised in that the layers
are bonded together by polymerisation of a synthetic resin.
14. Racket according to claim 5, characterised in that the wooden
layers of the lamination represent substantially the following
proportions in the width of the cross-section: between 20 and 40%
acacia, between 30 and 50% balsa, between 20 and 40% walnut.
15. Racket according to claim 1, characterised in that it is a
tennis racket.
Description
[0001] The invention relates to the field of rackets for sport or
various ball games. For the sake of convenience, the term "tennis
rackets" will be used hereinafter as the main, non-limitative,
illustration of the invention. The invention can also apply to
other types of-racket, for example squash rackets or any other
racket with a mesh delimited by a rigid frame.
[0002] Tennis rackets have undergone numerous technical
developments over time. Early generations of racket were made from
wood and naturally derive from the predecessor of tennis, jeu de
paume. In the 1930s, new wood adhesives made it possible to produce
glued-laminated rackets with several types of wood (ash, walnut,
beech, maple). These could withstand greater stresses and provided
a better balance between power and ball control.
[0003] New materials had to appear before there would be a
revolution in the world of rackets. Gradually, metal (steel,
aluminium, etc.) appeared in the 1970s. However, metal rackets
enjoyed only limited success. From the 1980s onwards, synthetic
fibres (carbon, fibreglass blend, etc.) made it possible to produce
rackets that were both light and powerful. These new materials
replaced wooden rackets which, due to their structure and
composition, could not rival the performance of the new materials.
Wooden rackets almost completely disappeared during the 1980s.
[0004] However, these technological advances prematurely cast aside
wood, which is a natural material that fits perfectly with an
eco-design approach that is very well perceived by users, and also
has remarkable technical properties that can rival synthetic or
processed materials, provided that the correct wooden structure or
composition is found for producing racket frames.
[0005] The object of the present invention is to propose a new
racket made principally from wood that uses a large proportion of
natural and renewable materials, while offering comparable
performance to rackets made from synthetic materials, which
currently occupy the entire market or almost the entire market.
[0006] To this end, the invention relates to a racket for ball
games, particularly tennis, comprising a frame delimiting a strung
surface forming a mesh, a handle extending the frame outside the
mesh, characterised in that the frame is formed, at least in a
peripheral region, from a bent lamination of at least two layers of
different materials placed adjacent to each other, the lamination
being shaped so that, in a closed cross-section of said peripheral
region, considered perpendicular to the neutral axis of the frame,
the centre of mass of said cross-section is offset towards the mesh
relative to the centre of area of said cross-section, by a value of
at least 5% of the width of said cross-section, said width being
defined by the intersection of the cross-section with the plane of
the mesh.
[0007] A tennis racket formed in this way offers excellent
performance in terms of handling, weight, mechanical strength,
ability to stabilise the frame on large deformations and ability to
filter micro-vibrations. A layer of a rigid, structural material on
which one or more layers of materials with the aforementioned
stabilising and filtering effects can rest is positioned towards
the mesh. A central layer is for example intended to stabilise the
frame on large vibrations while an outer layer, located away from
the mesh, is capable of filtering micro-vibrations. The denser and
therefore heavier (by unit of area of the cross-section) layers are
located closest to the mesh, which limits the inertia effects
relative to a longitudinal axis of the racket, or even relative to
the gripping handle of the racket. Conversely, the less dense and
therefore lighter (by unit of area of the cross-section) layers are
located on the outer periphery of the frame, on the side furthest
from the mesh. These layers are preferably intended to provide good
compressive strength of the frame, stabilisation on large
deformations and filtration of micro-vibrations.
[0008] Moreover, the layers of a racket frame according to the
invention are advantageously made from wood (with the exception of
an optional reinforcing sheath placed around one of the layers).
The frame according to the invention formed in this way uses over
75% natural and renewable materials, which constitutes a
particularly strong technical, ecological and commercial
argument.
[0009] According to further advantageous features of the invention,
the frame is formed from a lamination comprising at least two
layers of different materials, a first layer of which, located on
the inner side of the frame, has a greater density than the second
layer, located on the outer side of the frame.
[0010] According to further advantageous features of the invention,
the lamination is formed from at least three layers of at least two
different materials.
[0011] According to further advantageous features of the invention,
the lamination is formed from at least four layers of at least
three different materials.
[0012] According to further advantageous features of the invention,
the lamination comprises several layers of different types of wood,
said types of wood being chosen from acacia, balsa and walnut.
[0013] According to further advantageous features of the invention,
the lamination comprises at least one acacia layer located on the
inner side of the frame and delimiting the mesh. Acacia is a wood
with excellent mechanical properties. It is a highly responsive and
resilient wood. Placed on the inner periphery of the mesh, it forms
an excellent support for one of more layers located on the opposite
side to the mesh, and due to its density in relation to the other
layers, it makes it possible to move the centre of mass of the
cross-section towards the centre of the mesh. As an optional
variant, said at least one acacia layer can be formed of two acacia
layers. Said two layers can be arranged so that their fibres are
facing in the same direction or, conversely, in another optional
variant of the invention, so that their respective fibres are
facing in opposite directions.
[0014] According to further advantageous features of the invention,
the lamination comprises at least one walnut layer located on the
outside of the frame. Walnut is a low-density wood with
cross-grain, which gives it an ability to filter micro-vibrations
effectively.
[0015] According to further advantageous features of the invention,
the lamination comprises at least one balsa layer. This material is
appreciated for its great lightness.
[0016] According to further advantageous features of the invention,
said at least one balsa layer is inserted between said at least one
acacia layer and said at least one walnut layer. Said balsa core
has great compressive strength and forms an excellent stabiliser on
large deformations.
[0017] According to further advantageous features of the invention,
said at least one balsa layer is encased in a sheath made from
fibreglass or carbon or a mixture of both. Said sheath contributes
to the rigidity and cohesion of all of the adjacent layers.
[0018] According to further advantageous features of the invention,
the fibreglass sheath comprises a reinforcement selected from
carbon threads or basalt threads.
[0019] According to further advantageous features of the invention,
the layers are bonded together by polymerisation of a synthetic
resin.
[0020] According to further advantageous features of the invention,
the layers of wood of the lamination represent substantially the
following proportions in the width of the cross-section: [0021]
between 20 and 40% acacia, [0022] between 30 and 50% balsa, [0023]
between 20 and 40% walnut.
[0024] According to further advantageous features of the invention,
the racket is a tennis racket.
[0025] The invention will be more clearly understood on reading the
following description of a non-limitative embodiment of the
invention and with reference to the attached drawings, in
which:
[0026] FIG. 1 is a partial view of a tennis racket laid flat,
[0027] FIGS. 2 and 3 show a cross-section of the frame of the
racket in FIG. 1 along the line A-A, in perspective and
perpendicular to the plane of the cross-section respectively,
and
[0028] FIG. 4 is a perspective view of a longitudinal portion of
the balsa layer and its composite sheath.
[0029] FIG. 1 shows the frame of a tennis racket without its
handle. Conventionally, the frame 1 delimits a strung surface
forming a mesh 2. In the attached figures, the racket is shown
without strings. The handle 3 is connected to the frame by two
connecting arms 4, 5 as shown. In a variant (not shown), the handle
3 can be connected to the frame 1 by a single central arm.
[0030] According to an essential aspect of the invention and with
reference to FIGS. 1 to 3, the frame 1 is formed, at least in a
peripheral region, from a bent lamination of at least two layers
6-10 of different materials placed adjacent to each other, the
lamination being configured so that, in a closed cross-section T of
said peripheral region, considered perpendicular to the neutral
axis of the frame 1, the centre of mass M of said cross-section T
is offset towards the mesh 2 relative to the centre of area S of
said cross-section T, by a value of at least 5% of the width L of
said cross-section T, said width being defined by the intersection
of the cross-section T with the plane of the mesh 2.
[0031] The cross-section is said to be "closed" in the sense that
such a cross-section is only considered along a line A-A on one
side of the frame 1 only, and not on both diametrically opposite
sides. The centre of mass is defined as the centre of weight or
barycentre of the cross-section. Said centre of mass takes into
account differences in density, or more accurately relative mass,
in each area or region of the cross-section. The centre of area is
a geometric notion that corresponds to the centre of mass if the
entire cross-section were fictitiously homogeneous, i.e. made from
the same material with the same density or mass per unit of area in
all regions.
[0032] In particular embodiments of the invention, this offset can
for example be 10% or 20% or even more.
[0033] It must also be noted that an offset of the same magnitude
is provided between the centre of mass M of the cross-section T and
the neutral axis of the frame 1, the neutral axis conventionally
being defined in that it forms a fictitious line in which the
tensile or compressive forces are theoretically zero despite the
bending of the frame.
[0034] In the particular embodiment of the invention shown in FIGS.
1 to 3, provision is made for the frame 1 to be formed
homogeneously whatever the peripheral region considered. The
cross-sections are thus formed in the same way at any point on the
periphery of the frame 1. The adjacent layers 6-9 therefore have a
substantially annular shape corresponding to the general shape of
the frame 1.
[0035] According to the above definition of the invention, it will
be understood in other words that the frame is configured so that,
in at least one peripheral region, the mass or weight of the frame
is substantially concentrated towards the mesh, i.e. towards the
inside of the frame 1 rather than towards the outside. In the
example shown in FIGS. 1 to 3, the frame is configured so that said
concentration of mass or weight is provided evenly over the entire
periphery thereof.
[0036] The frame 1 is thus formed from a lamination comprising at
least two layers 6-9 of different materials, a first layer of
which, located on the inner side of the frame, has a greater
density than the second layer, located on the outer side of the
frame.
[0037] In the example shown, the frame 1 is formed from a
lamination with four layers 6-9 of three different materials. Said
materials are advantageously wood. The types of wood are selected
from acacia, balsa, walnut. Said types of wood are bonded and bent
in a conventional manner known to a person skilled in the art of
wooden rackets. In particular, the layers of wood are oven-bonded
together by polymerisation of a synthetic resin.
[0038] In the embodiment shown, the two layers 6, 7 located on the
inner side of the frame 1, i.e. adjacent to the mesh 2, are
preferably acacia. As acacia is an extremely responsive, resilient
wood, arranging it on the inner side of the mesh 2 turns it into a
support or bearing element for the other two layers 8, 9, which are
placed adjacent to it on the outer side from the mesh 2. As acacia
is relatively dense, arranging it on the inner side of the mesh 2
makes it possible to reduce the polar inertia due to the distance
of the masses from the centre of the mesh 2.
[0039] The two acacia layers are arranged so that their respective
fibres are in opposite directions to each other. The layers are
thus arranged head to toe. This arrangement increases the rigidity
of the two acacia layers, which limits the deformation thereof.
[0040] The laminated frame 1 also comprises a walnut layer 9
located on the outside of the frame, at least on the outer side in
relation to the acacia layers 6, 7. Walnut is a low-density wood
with cross-grain, which gives it an ability to filter
micro-vibrations effectively.
[0041] The frame 1 of the racket also comprises a balsa layer 8.
This is inserted between the two acacia layers 6, 7 and the walnut
layer 9. Said balsa core has great compressive strength and forms
an excellent stabiliser on large deformations.
[0042] In an equally advantageous manner, the balsa layer 8 is
encased in a fibreglass sheath 10, which can be seen in FIGS. 2 to
4. Said sheath contributes to the rigidity and cohesion of all of
the adjacent layers. The sheath 10 is arranged around the balsa
layer 8 in such a way as to form a reinforced central layer. The
acacia layers 6, 7 and walnut layer 9 are then placed on either
side of said reinforced central balsa layer 8, 10 prior to bending
and bonding.
[0043] Optionally and in no way limitatively, the fibreglass sheath
10 comprises a reinforcement selected from carbon threads or basalt
threads.
[0044] Considering the thicknesses of each wooden layer 6-9
relative to the width L of the cross-section T, the racket frame 1
according to the invention is proportionally defined as follows:
[0045] between 20 and 40% of the width L is acacia (all layers
combined), [0046] between 30 and 50% of the width is balsa, [0047]
between 20 and 40% of the width is walnut.
[0048] As shown in FIG. 2, the frame has a cross-section T with the
general shape of a rectangle with rounded edges. The layers 6-9 are
oriented parallel to the long sides of the rectangle. Thus, the
frame 1 leaves visible the edges of the different layers 6-9 on the
opposite parallel faces thereof, which correspond to the short
sides of the rectangle. It will also be noted that the rectangle is
deformed/domed on the inner side, i.e. on the side of the mesh 2.
The two acacia layers 6, 7 can therefore be of different
thicknesses and shapes.
[0049] Of course, the invention is not limited to the embodiments
described above and includes all technical equivalents.
[0050] For example, a variant embodiment of the invention can
comprise a single acacia layer on the inner side of the frame 1.
Provision can also be made for at least two balsa layers or at
least two walnut layers on the outer side of the frame 1.
* * * * *