Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
  • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
  • B29C44/04—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles consisting of at least two parts of chemically or physically different materials, e.g. having different densities
  • B29C44/06—Making multilayered articles
• • A—HUMAN NECESSITIES
  • A63—SPORTS; GAMES; AMUSEMENTS
  • A63C—SKATES; SKIS; ROLLER SKATES; DESIGN OR LAYOUT OF COURTS, RINKS OR THE LIKE
  • A63C5/00—Skis or snowboards
  • A63C5/12—Making thereof; Selection of particular materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
  • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
  • B32B5/245—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it being a foam layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
  • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
  • B32B5/28—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer impregnated with or embedded in a plastic substance
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
  • B32B5/32—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed at least two layers being foamed and next to each other
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B32/00—Water sports boards; Accessories therefor
  • B63B32/57—Boards characterised by the material, e.g. laminated materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/40—Symmetrical or sandwich layers, e.g. ABA, ABCBA, ABCCBA
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
  • B32B2260/02—Composition of the impregnated, bonded or embedded layer
  • B32B2260/021—Fibrous or filamentary layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
  • B32B2260/04—Impregnation, embedding, or binder material
  • B32B2260/046—Synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2266/00—Composition of foam
  • B32B2266/02—Organic
  • B32B2266/0214—Materials belonging to B32B27/00
  • B32B2266/0221—Vinyl resin
  • B32B2266/0228—Aromatic vinyl resin, e.g. styrenic (co)polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/546—Flexural strength; Flexion stiffness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/746—Slipping, anti-blocking, low friction
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/2419—Fold at edge
  • Y10T428/24215—Acute or reverse fold of exterior component
  • Y10T428/24231—At opposed marginal edges
  • Y10T428/2424—Annular cover
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24479—Structurally defined web or sheet [e.g., overall dimension, etc.] including variation in thickness
  • Y10T428/24496—Foamed or cellular component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24942—Structurally defined web or sheet [e.g., overall dimension, etc.] including components having same physical characteristic in differing degree
  • Y10T428/2495—Thickness [relative or absolute]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249924—Noninterengaged fiber-containing paper-free web or sheet which is not of specified porosity
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
  • Y10T428/249975—Void shape specified [e.g., crushed, flat, round, etc.]

Definitions

• the invention relates to the field of sliding boards comprising at least one sandwich-type laminated structure, that is to say a structure comprising at least three layers of superimposed materials, one of the layers, called the core layer, comprising a cellular material (not or slightly compressible), and being bonded on each of its faces to a layer of reinforcing material.
• These layers of material generally have a dimension (thickness) much smaller than their other dimensions, and the reinforcing layers generally have a thickness of at least 5 to 10 times less than the thickness of the core layer.
• laminated sandwich structures are appreciated for the very good ratio that they display between their weight and their mechanical strength, in particular from the point of view of their stiffness in sagging.
• the layers are bonded together, by any form of bonding, welding, etc., so that the bending of the structure results in a stressing of the (thin) reinforcing layers essentially in tension or in tension. compression, the core layer (thicker) being essentially stressed in compression in the direction of its thickness, and in shear in its general plane.
• the core layer light materials are generally used, most often cellular materials having a bulk density of less than 400 kg / m 3 and / or woody materials such as wood or other wood-based materials. . These materials are generally substantially rigid in compression in the direction of their thickness, at least in the field of efforts for which the structure is provided.
• the composite materials composed of fibers embedded in a plastic resin are appreciated for their mechanical characteristics and for their relative ease of use.
• other reinforcing materials are usable, such as metals (including aluminum), wood, or plastics with good mechanical properties.
• a sandwich laminate structure essentially comprises three interconnected layers, it may comprise complementary layers, either in the form of external layers superimposed on one or the other of the reinforcing layers, or in the form of intermediate layers. arranged between a reinforcing layer and the core layer . In the latter case, it is important to maintain a good bond between the different layers so that the shear forces can be transmitted from one layer to another.
• the invention will find a particularly interesting application in the field of floats for gliding on water, such as surf floats, kitesurfing or windsurfing.
• a surf float is made from a foam roll, in particular polyurethane foam, which is formed in a mold.
• the mousse bread is Machined by planing and sanding on a thin layer to locally customize its shape and form the core of the float.
• This core is then coated with a layer of a composite material comprising fibers impregnated with resin, this layer forming an outer reinforcing shell and giving the float its final shape.
• Various layers, such as a decoration, a glaze and / or a thermoformed protective sheet may be provided around the layer of composite material to give the float its final appearance .
• the float forms a laminated sandwich structure, with successively the composite top layer (comprising resin-impregnated fibers) forming the bridge, the light foam layer of the core, and the composite bottom layer forming the hull.
• the composite layers of the bridge and the hull form the reinforcing layers of the sandwich structure.
• a foam roll of relatively low density for example 18 kg / m3
• This core is covered with an outer shell, which in itself is a composite sandwich-like structure comprising an outer composite skin, a sheet of lightweight material, and an inner composite skin.
• an outer shell which in itself is a composite sandwich-like structure comprising an outer composite skin, a sheet of lightweight material, and an inner composite skin.
• hollow floats having an outer shell formed of a laminated sandwich structure.
• a ski or snowboard generally has a core which is made of foam and / or wood, and which is provided on its upper and lower faces with a reinforcing layer of composite material combining resin and fibers.
• This laminated sandwich-type structure is completed by other layers such as, below, a gliding sole, and, above, layers of decor and protection. It can also be supplemented with other layers of reinforcements, such as metal reinforcement layers.
• the invention can also be applied to the field of sliding boards with wheels, also called skateboards.
• the invention proposes a gliding board comprising a sandwich-type laminated structure, which comprises at least a first core layer of cellular material, a first reinforcing layer bonded to a first face of the first core layer, and a second reinforcing layer bonded to the second face of the core layer, characterized in that the laminated structure is reinforced at least locally by at least one layer of compressed foam which is arranged between the first layer) core and the first reinforcing layer and bonded to these two layers.
• FIG. 1 is a schematic perspective exploded view of a sandwich structure sample according to a first embodiment of the invention
• Figure 2 is a sectional view of the sample of Figure 1
• Figure 3 is a view similar to that of Figure 1 illustrating a second embodiment of the invention
• Figure 4 is a view similar to that of Figure 1 illustrating a third embodiment of the invention
• Figure 5 is a schematic top view of a sliding float comprising a sandwich structure according to the teachings of the invention
• FIG. 6 is a schematic cross-sectional view of the float according to the line
• FIG. 1 illustrates in exploded perspective a first example of a sample of a sandwich structure 10 according to the invention.
• the notions of "superior”, “lower”, “high” and “low” will be used with reference to the appended drawings, and only in order to facilitate the understanding of the description, without being limiting in nature. the scope of the invention.
• This structure is here composed of layers in the form of plates, in that they have a dimension (their respective thicknesses) much lower than their two other respective dimensions. These plates are essentially flat, but they could be curved in two or three dimensions, developable in the mathematical sense or not.
• the sandwich structure 10 thus comprises a core layer 12 of cellular material on both sides of which are arranged reinforcing layers 14.
• the cellular material of the core layer 12 is chosen from foams, in particular from so-called rigid foams.
• foams plastic flexible foams on the one hand and stiff foams on the other.
• Rigid foams have a low elasticity in that as soon as the compression force exceeds a certain value, they deform by collapse, irreversibly or very little reversible.
• From rigid foams include some polyurethane foams, expanded polystyrene foam and extruded polystyrene foam which are generally used in the form of foam rolls to form the cores of traditional surfboards.
• some foams of PVC or polyimide used generally as a core in the sandwich structure are part of so-called rigid foams.
• foams of expanded polyolefins are generally considered by those skilled in the art to be flexible foams, in particular by their capacity to be able to undergo large deformations in the elastic domain.
• the material of the core 12 is an extruded polystyrene foam such as that marketed by The Dow Chemical Company under the trademark “Styrofoam” and under the reference "HD300". This foam has a density of 45 kg / m3.
• any other cellular material may be considered, especially any cellular material of less than 150 kg / m 3, such as most plastic foams.
• the reinforcing layers 14 are advantageously layers of composite material such as fibers (glass, carbon, aramid, or mixtures thereof) impregnated or embedded in a resin (thermoplastic or thermosetting, for example of the polyester or epoxy type).
• the fibers will preferably be chosen from long woven fibers, with the possibility of superimposing several fabrics (identical or different, with different fiber orientations) within the same reinforcing layer 14.
• the sandwich structure 10 comprises, between the core layer 12 and at least one of the reinforcing layers 14 (in this case the upper reinforcing layer in the drawings), a layer of compressed foam 16 which is directly bonded or indirectly to these two layers 12, 14.
• compressed foam layer a layer of foam, in particular of plastic material, which has undergone a compression operation with plastic deformation, thus passing from a first stable state to a second stable state in which the layer of material has a thickness less than its initial thickness, this permanently. It follows that during this compression operation, the foam will have seen its bulk density increase in a ratio substantially equivalent to that of the decrease in its thickness.
• the compression operation will generally be performed as an operation prior to assembling the composite structure.
• this compression operation will be a thermocompression operation, that is to say carried out in the presence of a heat input, to bring the material in a state favorable to its plastic deformation capacity.
• the thickness of the compressed foam layer will be between 0.3 and 2 mm.
• thermocompression is performed with a minimum heating time before the actual compression phase, so that the foam plate does not have time to see its temperature to homogenize in the thickness. Under the effect of pressure, the outermost parts of the plate will be more easily deformable than the heart and will be more compressed.
• thermoforming operation with plastic compression could also be performed directly at the output of the foam production line, for example by calendering directly at the extruder outlet for the case of an extruded foam.
• connection between the different layers of the sandwich structure (essential so that the shear stresses are transmitted from one layer to another and so that the structure can function as a sandwich structure and not as a simple stack), can be performed in different ways, according to the procedures known to those skilled in the art for making sandwich structures.
• the reinforcing layers will be bonded to the core layer or to the foam layer compressed by said resin.
• reinforcement layers made of other materials, they may be bonded to the adjacent layer by a suitable adhesive.
• a simple bonding it may also be provided that this bonding is reinforced by fibers, woven or non-woven, long or short.
• This fiber-reinforced adhesive layer then forms a layer of interlayered composite material 15 between the compressed foam layer 16 and the core layer 12, these two layers then being indirectly bonded to each other. the other via the interlayer 15 which is bonded to both.
• FIG. 3 Such an alternative embodiment is illustrated in FIG. 3.
• This intermediate layer 15 can be made in the form of a reinforcing layer, for example combining fibers and resin, or in any other form of reinforcement layers as seen above. .
• the foam layer 16 thus compressed has the advantage of having a high resistance to any new compressive stress in a plane perpendicular to the structure. It thus protects the core layer from this type of stress which may appear for example when the sandwich structure is stressed in flexion. Indeed, in this case, the reinforcing layer 14 arranged on the internal side of the flexion (that which sees its concavity increase) is stressed in compression in its plane and may therefore tend to flare inwards, towards the core layer 12. As this is reinforced by the compressed foam layer 16, the reinforcing layer 14 is better held, and flambera for higher stress rates. Similarly, the structure will be stronger when a point load is applied perpendicular to its reinforced surface.
• the compressed foam layer has a thickness at least four times less than the thickness of the core layer.
• the thickness ratio between the core layer and the compressed foam layer it will be advantageous for the thickness ratio between the core layer and the compressed foam layer to be even greater, for example at least 10.
• the compressed foam layer is compressed to have substantially smooth upper and lower faces.
• the sample differs from the first only in that, according to a second aspect of the invention, the compressed foam comprises, on one of its faces (in the occurrence on its upper face arranged on the side of the upper reinforcing layer 14), engravings 30.
• the etchings 30 are carried out without removal of material, by simple plastic compression of the light material. They can thus be made by supporting a tool (for example a plate or a roll provided with ribs) in a direction substantially perpendicular to the general plane of the light layer, the tool leaving the impression of its ribs after have plastically compressed the material.
• a tool for example a plate or a roll provided with ribs
• the etching can be performed before, during, or after the foam compression operation.
• the etchings are formed during this step, for example by interposing a flexible grid between the material and the mold or the press (flexible or rigid ) of thermoforming. The pressure applied to the material during this operation, as well as the fact that it is brought to a temperature at which it is more plastic, allow the grid to leave an imprint on the corresponding surface of the compressed foam layer .
• the risk is limited that the etchings 30 become areas of rupture of the light material. Indeed, in terms of engravings made by plastic compression, the material is not destroyed or ripped.
• the engravings 30 may have various geometries.
• the engravings may for example have a V shape, a shape with parallel flanks and rounded bottom, or have a flared shape.
• they may be for example in the form of grooves (straight lines, curves, segments, etc.). They can form an ordered network (parallel, crossed paths, arranged in a particular symmetry etc.) or a random network. They may eventually draw geometric figures, or even decorative patterns or text elements.
• the etchings 30 form two crossed gratings of parallel lines drawing cells in parallelograms (rhombs, rectangles, squares, etc.).
• the engravings may have a depth of about 0.1 mm to 0.5 mm or more for relatively thick layers of compressed foam.
• the depth of the etchings may be just less than the thickness of the compressed foam layer, for example of the order of 0.9 times the thickness. In the latter case, the engravings will make the compressed foam layer particularly flexible and able to conform to a complex three-dimensional form, even if it is not developable.
• the etchings 30 are intended to be filled by the resin which forms the matrix of the composite material of the adjacent layer.
• This adjacent layer is, in FIG. 4, the upper reinforcement layer 14.
• the layer of composite material 14 has, on its interface surface with the compressed foam layer 16, raised ribs whose shape is directly complementary to the shape of the etchings 30 of the compressed foam layer 16.
• the polymerization step of the resin which impregnates the fibers under pressure is carried out, for example by arranging the laminated structure in a flexible membrane enclosure, and establishing a pressure differential between the inside and the outside of the membrane. the enclosure so that the flexible membrane intimately presses the layer of fibers and resin during polymerization against the compressed foam layer 16.
• the pressure differential can be obtained by creating a depression inside the speaker, or creating an overpressure outside the enclosure. In this way, it ensures a good flow of the resin between the fibers and into the etchings 30, thus forming the ribs.
• the engravings are filled with resin, it is particularly important that the engravings are shallow and narrow. Indeed, in the opposite case, the filling of engravings would consume a large quantity of resin, which could significantly increase the structure.
• the network of resin ribs which is thus created at the interface between the compressed foam layer 16 and the composite reinforcing layer 14 has many advantages. Firstly, the presence of this network makes it possible to increase the contact area between the two layers, thus increasing the adhesion surface between the two layers, and therefore their cohesion, thus limiting the risk of delamination of the layers. This aspect is reinforced by the fact that the combination of ribs and complementary engravings performs a mechanical attachment by complementarity of shapes that completes the chemical bonding of the resin on the material of the compressed foam layer.
• the ribs make it possible to increase the mechanical performances of the structure, in particular because the composite layer is reinforced by the ribs and in particular is more resistant to buckling when the composite layer is stressed in compression in its general plane, for example when the structure as a whole is stressed in flexion.
• the network of engravings 30 and complementary ribs is a multidirectional and repetitive geometric pattern. In this way, the reinforcing effect acts substantially homogeneously in all directions. Of course, with a pattern of more directional engravings, the reinforcement effect will also be more directional.
• the engravings are filled by a reinforcing reinforcement so that it is embedded in the compressed foam layer.
• the prints are made by pressing a grid (metal, fiber, etc. ..) in the surface of the compressed layer, and leave the grid in place in the layer of foamed material when the latter is integrated into the sandwich structure to strengthen.
• sandwich structures according to the invention may comprise other additional elements, either at level of the core layer (reinforcing structures for example or multi-material cores), reinforcing layers (for example additional protective layers or multi-material reinforcing layers, or any intermediate layers.
• FIGS. 5 and 6 illustrate the general external shape of a gliding float on the water 110, for example a surf float comprising, inside an outer envelope 112 float, an internal structure 114.
• the outer casing 112 forms, in its upper part, the bridge 112a of the float on which the user is intended to bear, and in its lower part, the hull 112b which bears on the water .
• the peripheral lateral edge of the outer envelope defines the rails 115 of the float.
• the outer casing 112 defines, in a sealed manner, a hollow internal space 117 of the float 110 in which is arranged the internal structure 114, which is in this case in the form of spacers 118, in this case three spacers 118, including a central 118a and two side 118b.
• the spacers 118 are provided to extend over the entire height of the internal space 117 of the float 110 so as to vertically connect the bridge 112a to the hull 112b.
• the spacers are made in the form of longitudinal retaining walls which extend parallel to one another over almost the entire length of the internal space of the float, substantially in the longitudinal direction of the float. latest.
• the partitions have a width of a few centimeters, for example about 1 to 4 centimeters.
• the spacers 18 are bonded, for example by gluing, to the two half-shells, and they are for example made of resiliently compressible plastic foam.
• the spacers each consist of two elements of plastic foam superimposed, the two elements differ in particular by their degree of elasticity.
• This structure determines a gliding board substantially hollow in the sense that it occupies only a part of the internal volume delimited by the envelope, preferably less than 60 percent of this volume.
• the internal structure 14 is preferably designed to allow a significant variation in the vertical distance separating the deck from the hull under the effect of the forces and the constraints imposed on the one hand by the user on the deck, and on the other hand by the water on the hull. Indeed, it appeared that the behavior of the float was improved by such a decoupling between the bridge and the hull.
• the outer casing 112 can be made in the form of two half-shells 112a, 112b, respectively forming the bridge and the hull, the half-shells being assembled to one another, for example by gluing along their joining plane which substantially follows the rails 115 of the float, to form a sealed outer envelope.
• the two half-shells 112a, 112b have a sandwich-type laminated structure in which a core layer 12, of alveolar or woody type, forming the core of the sandwich, is trapped between two inner and outer layers of reinforcing composite material 14 which form the skins of the sandwich.
• the skins 14 comprise, for example, layers of fibers (glass, carbon, aramid, etc.) embedded in a resin (thermoplastic, or thermosetting, for example of the polyester or epoxy type, etc.).
• the outer casing has a laminated composite sandwich structure which ensures its own strength, which nevertheless allows to benefit from the compressible nature of the spacers. Indeed, although rigid, these sandwich structures will be deformed, at least locally, under the forces induced by the use of the float.
• the core layer 12 is in this case formed by shaping an initially flat foam plate (in this case a rigid foam extruded polystyrene foam type, PVC foam, or rigid PU foam).
• the core layer 12 is preferably made with continuity of material over a significant portion of the structure.
• the shaping of the foam plate can be carried out by thermoforming.
• the laminated structure is reinforced by at least one compressed foam layer which is arranged between the core layer 12 and one of the reinforcing layer layers and bonded to these two layers.
• the bridge therefore comprises a reinforced sandwich structure according to the invention.
• the reinforced portion extends over the entire width of the deck of the board, and over a major part of the length thereof, with the exception of its front or rear ends.
• the reinforced portion could occupy only a portion of the width of the bridge.
• the reinforced part A could also be split into several parts, rather than a single part. On the contrary, it could occupy the entire surface of the bridge .
• other areas of the board could also be reinforced according to the invention, for example the hull, the rails or the nose of the float.
• the core layer has a disbursement 120 whose shape and depth corresponds to that of the compressed foam layer.
• a disbursement 120 can be achieved by local machining of the core layer, with removal of material, or by a thermoforming operation if the material is suitable.
• the operation of Thermoforming can be used to form and embed the compressed foam layer in the core layer.
• the board is a hollow board in the sense that the internal space 117 is substantially empty.
• the invention may be implemented in the case where it is wrapped with a reinforced sandwich structure. at least locally would cover a solid core.
• the invention which has just been described in the field of a surfboard float can also be used in the field of skis or snowboards, which generally consist of laminated sandwich structure using composite materials.
• ski 40 seen in cross section in which it is recognized from bottom to top: a gliding sole 42 framed by two metal edges 44; a lower reinforcing layer of composite material 46; a core 48 of cellular material and / or wood-based material; a top layer of reinforcement of composite material 50; a protective layer 52.
• the compressed foam layer has a substantially uniform density over its entire extent (if not over its entire thickness).
• the density of the layer is not uniform but, on the contrary, the foam layer has denser zones than others, these denser zones being for example arranged in zones subject to stronger constraints.
• the foam layer is made of several juxtaposed elements, each having undergone different compression ratios, or being made, at a constant compression ratio, from foams of different initial densities.
• the sandwich structure is reinforced only on one of these faces. This is particularly true for a structure that is asymmetrically solicited.
• the side of the structure which is most likely to undergo compressive forces perpendicular to the plane of the plates of the structure, and / or of the side of the structure for which the reinforcing layer is subjected to is preferably reinforced. compression in his plane.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• Ocean & Marine Engineering (AREA)
• Laminated Bodies (AREA)

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• 2005
  • 2005-10-24 FR FR0510815A patent/FR2892379B1/fr not_active Expired - Fee Related
• 2006
  • 2006-10-17 US US12/091,240 patent/US20080280096A1/en not_active Abandoned
  • 2006-10-17 EP EP06820230A patent/EP1940679A1/de not_active Withdrawn
  • 2006-10-17 WO PCT/FR2006/002336 patent/WO2007048898A1/fr active Application Filing

Non-Patent Citations (1)

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