SURFBOARD AND METHOD FOR MANUFACTURING THE SAME

Description

State of the art

[0001] The present invention relates to a device, in particular a surfboard for stand-up paddling, surfing, windsurfing and the like, and a method for producing a device in this regard.

[0002] Devices known from the state of the art, in particular surfboards for wave riding, stand-up paddling (SUPs), and also windsurfing, consist of a body made of foamed plastic, which is first machined from a block into its final shape and then covered with a fiber fabric impregnated with a matrix. In this case, the surface of the body can be additionally impregnated with the matrix before the impregnated fiber fabric is applied, so that sufficient matrix is ​​available that the fiber fabric is fully wetted with the matrix after curing. The matrix is ​​usually made of polyester resins, epoxy resins, or polyurethane resins. In the cured state, the resins generally behave like glass, i.e. they are hard and brittle.By incorporating a fiber fabric, such as fiberglass fabrics, in which the glass fibers have a predetermined alignment in a plane, or fiberglass mats, in which the glass fibers have no predetermined alignment in a plane, into the matrix, a high breaking strain and elastic energy absorption are generated. The higher the glass fiber content in a laminate, the better these properties. The bodies are usually made of extruded polystyrene (XPS) or expanded polystyrene (EPS), or polyurethane foam, which are very lightweight but cannot absorb high bending loads.

[0003] During use, a surfboard is exposed to high, sometimes sudden loads, which can lead to bending of the surfboard in all directions, particularly transversely to its longitudinal axis, which extends in the longitudinal direction of the surfboard, up to approximately 30 cm. It has been shown that surfboards of known types are sometimes unable to withstand these loads, and this can lead to the laminate detaching from the body. In order to create increased flexural rigidity in the surfboard, a corresponding number of laminates / laminate layers have been placed on top of one another in the past. However, this increases the weight of the surfboard on the one hand and limits the surfboard's elasticity on the other, which is certainly desirable in predetermined areas, particularly at its ends, namely the bow (nose) and the tail.

[0004] WO 2005 / 012074 describes a device, in particular a sports device for surfing or the like, comprising a base body made of foam, which has at least one laminate coating made of a fabric laminate and a bedding compound, wherein an intermediate layer is arranged between the base body and the laminate layer.

[0005] US Patent No. 4,188,428 describes a lightweight board element with a lightweight core made of rigid plastic foam and facings made of glass fiber reinforced resin. The upper and lower surfaces of the core are provided with closely spaced lattice-shaped recesses to increase the rigidity and hardness of the surface. Summary of the invention

[0006] There may therefore be a need to prevent a laminate layer from detaching from a body made of foamed plastic and to be able to adapt the bending line to the loads actually occurring.

[0007] This need can be satisfied by the subject matter of the independent claims. Advantageous embodiments arise from the subject matter of the dependent claims.

[0008] According to the invention, a device, in particular a surfboard for stand-up paddling, surfing, windsurfing and the like, is proposed, comprising a body made of foamed plastic, wherein the body is delimited by a surface to which a fiber mat is permanently connected. The surface has, at least in a partial region, at least one circumferential groove-shaped depression by which a predetermined partial area of ​​the surface is delimited, wherein the groove-shaped depression is formed by heating the surface and pressing a die over the fiber mat into the heated surface of the body, so that the fiber mat lies fully against the circumferential groove-shaped depression and foamed plastic has penetrated at least partially through the fiber mat.

[0009] Plastics with a low specific gravity are particularly suitable. To further reduce weight, the plastics are foamed. The foaming of the plastic can be done chemically or physically. The embedding of gas such as air, nitrogen or even carbon dioxide in the plastic can reduce weight. The plastics can be expanded or extruded plastics such as polystyrene or polyurethane. The plastics can be obtained wholly or partly from petroleum and / or renewable raw materials. The body can be made from a single layer of plastic or from several layers of plastic that can be bonded or welded together. By cleverly arranging the individual layers, the body can be designed to enclose one or more chambers filled with gas, preferably air.This allows the weight of the body to be reduced even further compared to a body that does not have gas-filled chambers. The bending and torsional rigidity of the device can also be influenced by cleverly selecting the individual layers from different plastics. Each individual layer can also be homogeneous, i.e. made from one plastic material, or heterogeneous, i.e. from different plastic materials. For example, fibers or rods made of unfoamed plastic can be embedded in a layer of possibly foamed plastic to change its strength. This plastic can be the same as the foamed plastic or different from the foamed plastic. Furthermore, a layer can also be inhomogeneous, i.e. the plastic can have a different specific density in different places.The fibers of a fiber mat can be made of glass, glass filaments, fiberglass, carbon, aramid, Dyneema, polyethylene, basalt, Texalium, parabean, or renewable raw materials such as hemp, flax, bamboo, jute, or sisal, or a mixture thereof. The fiber mat can be a woven fabric, a scrim, a nonwoven, or even made of rovings. The scrim can be monoaxial, also called unidirectional, biaxial, or multiaxial. The nonwoven is slightly flexible in any direction and is therefore particularly suitable for extending along the surface of the body, particularly into the depressions, and thus does not protrude from the surface at the transition from the depression to the partial surface. A nonwoven made of glass fibers with a weight of approximately 120 g / m² has proven to be successful, although other nonwovens with a weight between 20 g / m² and 200 g / m² can also be used.Fiber mats made of glass fibers will generally have a weight of between 50 g / m 2 and 480 g / m 2 . Fiber mats made of aramid fibers with a weight of between 60 g / m 2 and 400 g / m 2 are easy to process. The circumferential groove-shaped depression can be designed, for example, as a V-groove, rectangular groove, or concave groove. The side walls of the depression and the partial surfaces will generally enclose an angle greater than 90° to facilitate removal of the punch or die used to form the depression in the body. The partial surface can be flat, singly curved, or doubly curved, or a mixture thereof. The matrix can be unsaturated polyester resin, epoxy resin, vinyl ester resin, or polyurethane resin.The resins mentioned can be mixed with fillers such as hollow glass spheres, glass fiber chips, wood flour, talc, ground carbon fibers or hemp fibers, chalk, quartz flour, cotton flakes or silica, or a mixture thereof. By adding fillers, the properties of the resins can be modified for better processability or improved adhesion. The damping properties can also be changed by adding fillers. Furthermore, dyes can be added to the resins. The body can be board-like. However, the body can also have any three-dimensional shape. The body can also have structures on its upper side. These structures can be microscopic and / or macroscopic. In general, the body serves to space the matrix, or laminate, from the neutral fiber of the device.By adjusting the spacing of the laminate from the neutral fiber and the selected body structure, the bending and torsional strength, as well as the flex of the device, or rather the board, can be adjusted within a wide range. Furthermore, the plastics used for the body can be selected such that its surface is suitable for further processing into a composite device, meaning that the surface of the body can bond to the matrix, if necessary with the use of an adhesion promoter.

[0010] The circumferential groove-shaped depression can increase the surface area, so that a laminate layer consisting of at least one corresponding fiber mat and a matrix can rest on a larger area than a surface without depressions. The surface area enlarged by the circumferential groove-shaped depression can result in more adhesive forces, which can thus lead to an improved bond between the laminate layer and the foamed plastic of the body. Furthermore, the matrix can be adjusted by suitable measures so that it can penetrate into the body and thus, after curing, form a positive connection between the laminate layer and the body, which can improve the bond between the laminate layer and the body. In addition, the surface of the body can also be increased by increased roughness.The increased roughness can primarily lead to an increase in the adhesion forces that prevent the laminate layer from detaching from the surface of the body. In addition to the adhesion forces, it can also lead to mechanical wedging of the cured matrix in the pores that form the roughness. The circumferential groove-shaped depression can delimit a partial area of ​​the surface with any desired contour. The circumferential groove-shaped depression can not only increase the surface area to increase the adhesion forces of the laminate layer to the body, but also the flexural rigidity around and across the longitudinal axis extending in the longitudinal direction of the device. A transverse axis and a vertical axis can extend across the longitudinal axis. In this case, all axes enclose a right angle to one another.Thus, by maintaining a constant or varying depth of the circumferential groove-shaped depression and by adjusting the surface area of ​​the partial surface defined by the circumferential groove-shaped depression, the stiffness against rolling, pitching, and yawing can be adapted to the actual loads, at least to a large extent, if not entirely. The groove-shaped circumferential depressions in combination with the fiber mat, particularly a fiber mat made of nonwoven fabric, enable the surface to absorb more pressure without creating pressure marks on the surface, which not only have an unsightly appearance but can also represent a micro-detachment of the laminate layer from the body.This can be explained by the fact that the laminate layer itself does not have the shape of a plate, as is the case with state-of-the-art surfboards, but rather the portion of the laminate layer extending along the groove-shaped depressions acts as reinforcing ribs. Accordingly, a pressure acting essentially perpendicular to the laminate layer can be absorbed by the reinforcing ribs. Accordingly, only a small portion of the pressure acting on the laminate layer is transferred to the body. The nonwoven fabric can also ensure that the pressure acting on the laminate layer is distributed evenly within the laminate layer before it is transmitted to the reinforcing ribs. This can lead to a longer operating life. The proposed device can also maintain constant flexural properties over a long period of time.Additionally, an additional reinforcement, for example made of a matrix-impregnated carbon strip, can be inserted beneath the first laminate layer, particularly in conjunction with a surfboard, in a linear groove-like depression arranged on the surface, which can extend essentially straight along a center line extending in the direction of the longitudinal extent. In such a configuration, the laminate layer that extends as the first ply at least partially along the circumferential groove-like depression is referred to as the first laminate layer. To further increase the flexural rigidity, additional laminate layers can be applied to the first laminate layer.These additional laminate layers can either extend along a surface of the bottommost laminate layer, thus forming the partial surfaces and the depressions on their respective upper surfaces, or the additional laminate layers can be flat on their upper surfaces, thus extending only along the partial surfaces and leveling the circumferential groove-shaped depressions. Leveling can be achieved, for example, by filling with the matrix, optionally with the addition of fillers. It is understood that the circumferential groove-shaped depressions can be formed on the upper surfaces, undersides, and / or narrow sides of board-shaped devices. The circumferential groove-shaped depressions can also be combined with non-circumferential groove-shaped depressions.For example, in a device in the form of a surfboard, a substantially rectilinear depression may extend substantially from bow to stern, which depression is filled, for example, with a laminate layer containing carbon fibers.

[0011] According to a further embodiment of the invention, a second partial surface with a second circumferential groove-shaped depression adjoins the first partial surface with the first circumferential groove-shaped depression.

[0012] By increasing the number of sub-areas defined by circumferential groove-shaped depressions, which are appropriately adjacent to one another and can potentially vary in surface area, the stiffness against bending around the longitudinal, transverse, and vertical axes can be more differentiated. Furthermore, the additional circumferential groove-shaped depressions can increase the surface area and thus the contact area of ​​the laminate layer. This can also lead to an improved bond between the body and the laminate layer.

[0013] According to a further embodiment of the invention, a predetermined portion of the first circumferential groove-shaped depression of the first partial surface forms a predetermined portion of the second circumferential groove-shaped depression of the second partial surface adjacent to the first partial surface.

[0014] Thus, adjacent sub-areas share portions of the recesses that would otherwise extend side by side. This can reduce the need for matrix and fiber mat compared to a device in which the groove-shaped recesses of each sub-area are individually formed circumferentially, without using portions of the groove-shaped recesses of the adjacent sub-area. This can lead to weight and material savings without significantly reducing the stiffness against bending around the longitudinal, transverse, and vertical axes.

[0015] According to a further embodiment of the invention, the partial region of the surface of the body has a plurality of partial surfaces delimited by circumferential groove-shaped depressions which adjoin one another and in which predetermined partial sections of the circumferential groove-shaped depression of one partial surface are formed by predetermined partial sections of the circumferential groove-shaped depression of an adjacent partial surface.

[0016] Thus, by a predetermined arrangement of the groove-shaped depressions in the partial area of ​​the surface, a network of adjoining partial areas can be created without groove-shaped depressions extending next to one another in mutually touching relationship.

[0017] According to a further embodiment of the invention, the circumferential groove-shaped depression is formed by a series of track sections or curved sections or a mixture of track sections and curved sections.

[0018] From a series of track sections and curve sections, any two-dimensional geometric figure can be created in a top view of the surface of the body, which can be formed by the circumferential groove-like depression in the body.

[0019] According to a further embodiment of the invention, the circumferential groove-shaped depression has a contour of a hexagon which has at least four first sides of substantially equal length, each lying opposite one another in pairs, and two second sides of substantially equal length, each lying opposite one another.

[0020] The two opposite second sides, which are essentially the same length, can be longer or shorter than the remaining four first sides. The included angle between any two adjacent sides can be essentially 60°. This special hexagonal shape can provide almost perfect use of space because there are no gaps between the individual hexagons. Of all the shapes that can be aligned seamlessly, hexagons can have the best ratio of stiffening, or recess, to frequency in relation to the required stiffness. This means that compared to all other geometric shapes, hexagons aligned in a row require the fewest laminate layers to achieve a given stiffness. The hexagons can also be aligned so that the variable pair of sides extends in the direction of the longitudinal axis.The length of this pair of sides can also increase compared to the other two pairs of sides towards the bow or stern in order to allow a greater deflection of the bending line under constant force and an essentially constant depth of the circumferential groove-shaped depressions. Of course, the variable pair of sides can extend transversely to the longitudinal axis or at any angle to it. For structural components, the opposite approach can also be taken, with the two pairs of sides having the shortest length at the ends and successively increasing towards the center of the structural component. According to a further embodiment of the invention, the circumferential groove-shaped depression is designed as a regular hexagon.

[0021] This design, in which all sides are essentially the same length, is also known as a honeycomb structure. The circumferential groove-shaped depressions extend essentially in the direction of the vertical axis into the body. Although the regular hexagonal shape is not rotationally symmetrical, in practice it is calculated as if the strength is the same in all directions. A honeycomb structure with circumferential groove-shaped depressions in the body can result in high mechanical rigidity with low weight. In order to influence the bending line about one axis or all three axes, the depth of the circumferential groove-shaped depressions can be varied, for example, while the surface area of ​​all partial surfaces is the same.

[0022] According to a further embodiment of the invention, each partial area has a surface area, wherein the surface areas are at least partially of different sizes.

[0023] Typically, the surface area will increase continuously toward the ends along the longitudinal axis to allow for a defined deflection under a predetermined force. In the transverse axis direction, the surface areas can be the same or can also vary to create a defined deflection line under a predetermined force.

[0024] According to a further embodiment of the invention, a depth that the circumferential groove-shaped depression penetrates into the body, measured from the surface of the adjacent partial area, is approximately 0.5 mm to approximately 15 mm, preferably approximately 2 mm to approximately 10 mm and particularly preferably approximately 3 mm to approximately 5 mm.

[0025] The smaller the depth of the circumferential groove-shaped recess, the lower the stiffness against bending can be.

[0026] According to a further embodiment of the invention, the depth of a groove-shaped depression is constant.

[0027] In conjunction with groove-shaped depressions of constant depth, the surface areas of the partial surfaces can be constant or variable. A particularly simple calculation of stiffness is obtained for regular hexagons with groove-shaped depressions of the same depth arranged in a continuous row.

[0028] According to a further embodiment of the invention, the depth of a circumferential groove-shaped depression changes.

[0029] If there is only one circumferential groove-shaped depression in the partial area of ​​the surface, the stiffness against bending can be changed by varying the depth of the circumferential groove-shaped depression while keeping the area of ​​the partial area constant.

[0030] According to a further embodiment of the invention, the depth of the circumferential groove-shaped depressions of two adjacent partial surfaces is different.

[0031] The depth within one circumferential groove-shaped depression can change in such a way that, in conjunction with adjacent circumferential groove-shaped depressions, a continuous decrease or increase in the depth of the individual circumferential groove-shaped depressions can be achieved, for example, towards the ends of a surfboard. This allows the stiffness against bending, also known as flex, to be influenced in a predetermined manner. The change in depth can also occur in steps. It is understood that by changing the surface area of ​​the partial surfaces and / or changing the depth of the circumferential groove-shaped depressions, the stiffness against bending about the longitudinal axis, the transverse axis, and / or the vertical axis can be influenced.

[0032] According to the invention, the fiber mat lies completely against the circumferential groove-shaped depression and foamed plastic has penetrated at least partially through the fiber mat.

[0033] As the plastic from which the body is made passes through the fiber mat, a firm bond is created between the fiber mat and the depression, or rather, to the wall bordering the circumferential groove-shaped depression. This can be achieved, for example, by heating a punch or die, which has a raised portion corresponding to the circumferential groove-shaped depression, and then pressing it with a predetermined force onto the body covered with the fiber mat, which does not have a circumferential groove-shaped depression. The temperature is set so that the plastic of the body melts beneath the die, passes through the fiber mat, and cools after the punch or die is removed. The plastic that has passed through the fiber mat solidifies.This procedure allows processing not only nonwovens, which are highly flexible in all directions, but also woven or nonwoven fabrics, which are relatively rigid compared to nonwovens. It is understood that to achieve a predetermined temperature on the surface of the body, the stamp can be pressed against the fiber material and thus against the surface of the body with a predetermined pressure for a predetermined period of time, depending on the thermal conductivity of the fiber material and its thickness.

[0034] According to a further embodiment of the invention, the body has a core and an intermediate layer extending between the core and the surface with a predeterminable thickness, wherein the intermediate layer is filled with the matrix.

[0035] It is precisely this intermediate layer with the matrix that prevents the interfacial stress that occurs between the laminate layer and the surface when devices manufactured according to the state of the art are subjected to load. Instead, this intermediate layer gradually reduces the stress generated by the application of force. Thus, for a given force, the appropriate thickness of the intermediate layer and its elasticity can reduce the stresses that occur to such an extent that they cannot damage the core. This design also effectively prevents the laminate layer from detaching from the body. The intermediate layer is essentially determined by the penetration depth of the matrix and its elasticity in the cured state. To influence the penetration depth, the consistency of the liquid matrix can be adjusted.For example, a particularly thin matrix can be used, or the consistency of the liquid matrix can be reduced by heating. When using epoxy resin as the matrix, for example, the elasticity of the cured matrix can be further increased by reducing the amount of hardener added. Typically, the concentration of the matrix in the intermediate layer is reduced to a certain level. The thickness of the intermediate layer can be increased by choosing an open-cell foam over a closed-cell foam.

[0036] According to a further embodiment of the invention, a second laminate layer comprising a fiber mat and a matrix is ​​laminated onto an upper side of the laminate layer extending on the surface of the body, wherein a lower side of the second laminate layer extends along the upper side of the laminate layer.

[0037] By extending the underside of the second laminate layer along the upper side of the first laminate layer, which is firmly bonded to the surface of the body, the contour of the depressions is essentially reproduced on an upper side of the second laminate layer opposite the upper side of the first laminate layer. Thus, the upper side of the second laminate layer has circumferential groove-shaped depressions. The second laminate layer can differ from the first laminate layer with regard to the fiber mat and / or the matrix. For example, the fiber mat of the first laminate layer can be nonwoven fabric and the fiber mat of the second laminate layer can be glass fiber fabric. The second laminate layer can reinforce the construct of the body and the first laminate layer in all three axes. It is not necessary for the first and second laminate layers to completely envelop the surface of the body.It may be possible for the surface of the body to be covered by the first laminate layer only in one or more partial areas and for the second laminate layer to only cover the remaining partial areas of the surface. The second laminate layer can also envelop the entire body and thus also the partial area covered by the first laminate layer. It is understood that the second laminate layer can be applied to the first laminate layer using the so-called wet-on-wet process. In this process, the matrix of the first laminate layer has not yet cured before the matrix of the second laminate layer is applied. Alternatively, the second laminate layer can be applied to the first laminate layer after a peel ply has been removed from the first laminate layer, under which the matrix of the first laminate layer has cured.

[0038] According to a further embodiment of the invention, a second laminate layer made of a fiber mat and a matrix is ​​laminated onto an upper side of the laminate layer extending on the surface of the body, wherein an underside of the second laminate layer extends exclusively along the upper side of the laminate layer of the partial surfaces, so that the upper side of the second laminate layer is flat.

[0039] The underside of the second laminate layer extends only along a portion of the top side of the first laminate layer, which is firmly connected to the partial surface of the surface. The second laminate layer can bridge the circumferential groove-shaped depression formed on the top side of the first laminate layer by filling the circumferential groove-shaped depression formed on the top side of the first laminate layer flush with the partial surface using a matrix to which a filler may have been added. The top side of the second laminate layer can therefore be essentially flat. As a rule, there are no air bubbles in the first laminate layer, the second laminate layer, or the matrix that levels the circumferential groove-shaped depression. It is understood that additional laminate layers can also be applied to the second laminate layer.Depending on the desired size and shape, fiber mats such as carbon basalt or Dyneema can also be inserted as reinforcements between the laminate layers in predetermined areas.

[0040] Furthermore, according to the invention, a method for producing a structural component with reinforcement made of a fiber-plastic composite, in particular a surfboard for stand-up paddling, surfing, windsurfing, and the like, with a body made of plastic is proposed, wherein the body is delimited by a surface to which a fiber mat is permanently connected. The method comprises the following method steps: applying the fiber mat to the body delimited by the surface and subsequently forming at least one circumferential groove-shaped depression in at least a partial area of ​​the surface by heating the surface and pressing a die against the fiber-plastic composite, wherein a predetermined partial area of ​​the surface is delimited by the circumferential groove-shaped depression.

[0041] Thus, the at least one depression can be produced through the fiber mat. Typically, the depression is created on the surface by applying a predetermined force using a stamp with a raised portion corresponding to the at least one depression.

[0042] According to a further embodiment of the invention, a stamp is heated to a predetermined temperature, wherein the stamp has at least one elevation corresponding to the circumferential groove-shaped depression.

[0043] By heating the stamp, the force required to create the depression is reduced. The stamp can be heated to a temperature that can lead to the melting of the foamed plastic. The temperature can therefore depend on the plastic selected. The depth of penetration of the stamp into the body can also be regulated by the temperature when a predetermined force is applied to the stamp. Thus, with constant force, the stamp can penetrate deeper at a higher temperature than at a lower temperature. The molten plastic can penetrate through the fiber mat and thus cause the fiber mat to adhere to the depression or to the wall of the depression. This can create a particularly tight bond between the body and the first laminate layer after the fiber mat has been impregnated with the matrix. The stamp can be heated, for example, by induction or using an external heat source.Induction heating may be appropriate if the stamp is made of a ferromagnetic material. Electric heating cartridges, such as those used in injection molding technology to heat injection molds for plastics processing, can also be used to heat the stamp. The stamp can also be equipped with a temperature sensor to monitor the stamp temperature. This temperature sensor can be coupled to a temperature control device to regulate the temperature so that the stamp reaches a predetermined temperature.

[0044] According to a further embodiment of the invention, the surface of the body is heated above the melting point of the plastic and then the stamp is pressed into the part of the body covered with the fiber mat. The surface of the body can be heated through the fiber mat. This can be achieved, for example, by exciting the dipoles of some types of plastic (polar plastics) using high frequency. Ultrasonic waves can also generate internal friction in the plastics, which can lead to melting of the surface of the body. Hot gas, in particular hot air, can also be used to heat the surface of the body and is passed over the fiber mat. This can have an advantage in the production cycle time, since it can decouple the formation of the groove-shaped depressions from the melting of the surface of the body. This can also enable continuous production.

[0045] According to a further embodiment of the invention, the stamp has all elevations corresponding to the circumferential groove-shaped depressions.

[0046] This allows all partial surfaces to be created in a single operation. The punch, also called a die, can be the size of the portion of the surface containing the circumferential groove-shaped depressions. If the groove-shaped depressions extend in a network over the entire surface of the device, the die can be the size and shape of the entire surface, or more than one die can be used to cover the entire surface.

[0047] According to a further embodiment of the invention, the predetermined temperature of the stamp is between about 90°C and about 220°C, preferably between about 120°C and about 180°C, and particularly preferably between about 140°C and about 160°C.

[0048] The temperature can be selected depending on the melting point of the foamed plastic from which the body is made. The temperature along the die can also exhibit a temperature profile in order to create different penetration depths of the die into the body with a constant force. A temperature profile within the die can be conveniently generated by using multiple heating cartridges. The die can be produced, for example, using primary forming technology, i.e., by applying and fusing individual layers using a laser, or by machining, preferably by milling. Dies can also be produced using CNC technology, which can be one- or two-dimensionally curved.As a rule, the size and shape of the die are selected so that all desired circumferential groove-shaped depressions can be created on one surface of the structural component, i.e., the front surface, side surface, or rear surface, in a single operation. A typical manufacturing method for producing the structural component can be to envelop the body, which can be made of expanded polystyrene, for example, with a fiber mat, which can be a woven glass fiber fabric, and to apply the die in the partial area where the circumferential groove-shaped depressions are to be formed, the elevations of which form a honeycomb shape. If the die has already been heated to the predetermined temperature by an external heat source, the heated die can be pressed with a predetermined force against the fiber mat, which is at least substantially in contact with the surface of the body.If the die has a lower temperature than the predetermined temperature when pressed against the fiber mat, the die can now be heated to the predetermined temperature, for example using the heating cartridges. The die can be pressed against the fiber mat, for example, in a hydraulically or pneumatically operated press. Pneumatic or hydraulic cylinders can also act directly on the die. When operating with several cylinders distributed along the longitudinal extent of the structural component, the contact pressure on the individual pressure points on the die can vary. The force acting on the die can also be applied mechanically, e.g. using threaded or toggle lever constructions. Depending on the plastic used, the die can be heated to approximately 150°C. At this temperature, the foamed plastic can melt.The molten plastic can penetrate the fiber mat and harden after cooling. In this case, the fiber mat can essentially lie completely against the depression or against the wall of the depression. After the fiber mat-body composite has been separated from the matrix, the fiber mat can be impregnated with a matrix. This can be done by impregnating the fiber mat with a matrix. According to the prior art, the matrix can also be covered with a peel ply, the fiber mat-body composite impregnated with the matrix is ​​placed in a vacuum bag and hardened under negative pressure. This can force the matrix into the fiber mat. In addition, matrix can also penetrate into the body. Furthermore, an absorbent fabric can be placed on the peel ply, which can absorb excess resin that is not absorbed by the body and / or the fiber mat.After removing the peel ply, a second laminate layer made of, for example, glass fiber fabric and the same matrix can be applied to the laminate layer of fiber mat and matrix, which is also pressed against the first laminate layer in the vacuum bag by negative pressure.

[0049] According to a further embodiment of the invention, the stamp is pressed against the surface of the body via the fiber mat at a predetermined pressure for a predetermined period of time. In this case, the stamp can be pressed against a first partial area with a first pressure at a predetermined temperature onto the heated surface of the fiber mat, which rests on the surface of the body in at least a partial area, for a first predetermined period of time. Subsequently, the stamp can be pressed against a second partial area with a second pressure at the same predetermined temperature onto the heated surface of the fiber mat, which rests on the surface of the body in at least a partial area, optionally for a second predetermined period of time, wherein the first pressure is different from the second pressure.This allows the penetration depth of the stamp into the body in the first section to be different from the penetration depth in the second section. Depending on the plastics used, it may be necessary to adjust the residence time of the stamp in the body in the retracted state to allow the molten plastic to sufficiently penetrate the fiber mat.

[0050] According to a further embodiment of the invention, the device is used as a surfboard for stand-up paddling, surfing, windsurfing, and the like. During operation, a bottom side floats on the water, and the top side opposite the bottom side has a surface that, at least in a partial region, has at least one circumferential groove-shaped depression that delimits a predetermined partial area of ​​the surface.

[0051] Only the top side of the device or only the bottom side of the device can have at least one circumferential groove-shaped depression or the bottom side and the top side of the body can each have at least one circumferential groove-shaped depression.

[0052] It should be noted that features of the device may, where appropriate, also serve as features of the method, and vice versa.

[0053] Embodiments of the invention are described below with reference to the accompanying figures. The figures are merely schematic and not to scale. Short description of the characters

[0054] Fig. 1 shows a plan view of a section of a device with hexagonal circumferential groove-shaped depressions in a partial area with a laminate layer; Fig. 2 shows an enlarged section of the Fig. 1shown partial area of ​​the device in plan view; Fig. 3 shows a first alternative embodiment of the circumferential groove-shaped depressions in plan view; Fig. 4 shows a second alternative embodiment of the circumferential groove-shaped depressions in plan view; Fig. 5 shows a surfboard with honeycomb-shaped circumferential groove-shaped depressions in plan view; Fig. 6 shows a cross section through a section of the Figure 1 known device; Fig. 7 shows a cross section through a section of the Figure 1 known device with a second laminate layer in a first embodiment; Fig. 8 shows a cross section through a section of the Figure 1 known device with a second laminate layer in a second embodiment; and Fig. 9 shows a process flow for manufacturing the device. Detailed description of exemplary embodiments

[0055] At this point it should be noted that identical parts in the individual figures have the same reference numerals.

[0056] Figure 1shows a plan view of a section of a proposed device 10. The device 10 consists of a board-like body 12 made of expanded polystyrene. However, the body 10 can also have any other 3-dimensional geometric shape. The body 10 itself can also be produced in a sandwich construction from several layers of plastic. In this case, the plastics can be homogeneous, inhomogeneous and / or heterogeneous. Chambers filled with gas, preferably air, can also be provided in the body. The body 10 is delimited by a surface 14, to which a first laminate layer 16 made of a fiber mat, namely a nonwoven fabric made of glass fibers, and a matrix, namely epoxy resin, is permanently bonded. The surface 14 has a partial area 18 in which a plurality of circumferential groove-shaped depressions 20 are formed, which cover the partial area 18 of the surface 14 in a net-like manner.The circumferential groove-shaped depressions 20 delimit partial areas 22 with a predetermined area.

[0057] Figure 2shows an enlarged section of the partial area 18 of the surface 14 of the device 10 coated with the laminate layer 16. A first groove-shaped depression 20' is formed circumferentially and delimits a predetermined first partial area 22' of the surface 14. The first circumferential groove-shaped depression 20' forms a regular hexagon 30. All segments 32 from which the hexagon 30 is formed are of equal length. Accordingly, the angles α included between the adjacent segments 32 are also essentially the same size, namely 60°. Adjacent to the first partial area 22' with the first circumferential groove-shaped depression 20' is a second partial area 22" with a second circumferential groove-shaped depression 20". This second circumferential groove-shaped depression 20" is also formed as a hexagon 34. However, the hexagon 34 differs from the regular hexagon 30.The hexagon 34 has four opposite sides 36, each in pairs, which are essentially the same length as the sides of the regular hexagon 30. Two opposite sides 38 of the second circumferential groove-shaped depression 20" extending in the direction of the longitudinal axis II are longer than the other sides 36. Accordingly, the first partial area 22' delimited by the first circumferential groove-shaped depression 20' formed as a regular hexagon 30 is smaller than the second partial area 22" delimited by the second circumferential groove-shaped depression 20" formed as a hexagon 34.

[0058] Figure 3shows a first alternative embodiment of the circumferential groove-shaped depressions 200, 210, which, in plan view, represent a circular shape, with each circle 200, 210 having the same diameter. Five circles 200, 210 are shown, four of which 200 are arranged next to and below one another at a distance from one another. Connecting lines g, which connect the centers of the adjacent circles 200, are either parallel to one another or perpendicular to one another. Each of the four circles 200 is spaced equally apart from the neighboring circle. The fifth circle 210 is arranged centrally between the four circles 200 and extends into each of the four circles 200. This arrangement results in nine partial areas 220, 222, 224 with essentially three different surface areas. Each of the four circles 200 includes a first partial area 220.Furthermore, there are four second partial areas 224, which are bounded by the fifth circle 210 from a total area of ​​each of the four circles 200. The fifth circle includes a third partial area 222.

[0059] Figure 4shows a second alternative embodiment of the circumferential groove-shaped depressions 300, 300', 310, 310' in plan view. Nine circumferential groove-shaped depressions 300, 300' are circles of the same diameter. These circles 300, 300' are shown in a 3x3 arrangement, i.e., in the present embodiment example, three rows arranged one below the other, each with three circles 300, 300' arranged next to one another. The centers of the adjacent circles 300, 300' are spaced apart from one another by a distance greater than the diameter of a circle 300, 300'. In the present embodiment example, each connecting line g through the centers of adjacent circles 300, 300' extends either along the longitudinal axis II or at right angles thereto, i.e., along the transverse axis II-II.Each tile-shaped partial surface 320, 320' is bounded by the circumferential groove-shaped depression 310, 310', which results from an alternating series of track sections 302 and curved sections 304. The straight track sections 302 of the circumferential groove-shaped depression 310 of a partial surface 320 form a section of the circumferential groove-shaped depression 310' of the adjacent partial surface 320'. The curved sections 304 that bound the tile-shaped partial surface 320 also each form a section of the circular circumferential groove-shaped depression 300, 300' of the circular partial surfaces 322 adjacent to the tile-shaped partial surface 320.

[0060] Figure 5shows the device 10 in the form of a surfboard, which has circumferential groove-shaped depressions 20' extending over the entire surface 14, each of which has the shape of a regular hexagon 30, a so-called honeycomb, with essentially the same surface area 22'. Two opposing track sections 32 extend essentially parallel to a longitudinal axis II, along which the surfboard 10 extends. Each track section 32 forms a portion of the circumferential groove-shaped depression 20' of adjacent partial surfaces 22'.

[0061] Figure 6 shows a cross-section through a section of the Figure 1 known device 10 along a Figure 1visible section line AA. The cross section extends along a vertical axis III-III which is perpendicular to the longitudinal axis II and the transverse axis II-II. The surface 14 delimiting the body 12 has partial surfaces 22 which are delimited by circumferential groove-shaped depressions 20. The laminate layer 16 extends along the surface 14 and is permanently connected to the surface 14. In the exemplary embodiment shown here, a depth t, t' varies and extends from the partial surface 22 to a deepest point of the circumferential groove-shaped depression 20. The different depths t, t' are clearly visible in this exemplary embodiment. The depths can be approximately 0.5 mm to approximately 15 mm. In the present exemplary embodiment, the greater depth t is 5 mm and the smaller depth t' is 3 mm.Not shown in this exemplary embodiment is the penetration of the foamed polystyrene from which the body 10 is made through the nonwoven fabric made of glass fibers. Matrix 26 extends from the laminate layer 16 into the body 12 and forms an intermediate layer 40 between the surface 14 and a core 42 of the body 12. This intermediate layer 40 prevents any boundary stress between the laminate layer 16 and the surface 14. Rather, a force acting on the laminate layer 16 is at least partially absorbed by the intermediate layer 40, in which a portion of the matrix 26 from the surface 14 to the core 42 is reduced to a predetermined level, and only the remaining force is directed into the core. Figure 7 shows a cross-section through a section of the Figure 1 known device 10 along the Figure 1visible transverse axis II-II. Here, too, the cross-section extends along the vertical axis III-III. A second laminate layer 44 extends along an upper side 41 of the first laminate layer 16 and is permanently connected to the first laminate layer 16. Thus, the second laminate layer 44 extends along the circumferential groove-shaped depressions 20 and, on its upper side 46, forms the surface 14 with the circumferential groove-shaped depressions 20.

[0062] Figure 8 shows a cross-section through a section of the Figure 1 known device 10 along the Figure 1visible transverse axis II-II. Here too, the cross section extends along the vertical axis III-III. In contrast to the embodiment of Figure 7, the circumferential groove-shaped depressions 20 formed on the upper side 41 of the first laminate layer 16 are filled with a filled matrix 28. A filled matrix 28 is achieved by adding filler in the form of glass fiber chips to the matrix in the present exemplary embodiment. A filled matrix 28 can harden stress-free even in larger layer thicknesses and can be elastic due to the fillers. Sufficient filled matrix 28 is filled into the depressions 20 formed on the upper side 41 of the first laminate layer 16 that the depressions 20 are bridged and a second laminate layer 44' is permanently connected to the first laminate layer 16 in the region of the partial surfaces 22 and to the filled matrix 28 in the region of the depressions 20.The second laminate layer 44' forms a substantially planar upper surface 46'.

[0063] The circumferential groove-shaped depressions allow the surface to be enlarged, allowing the laminate layer to rest on a larger area than a surface without depressions. The increased surface area created by the groove-shaped depression allows for greater adhesion forces, thus improving the bond between the laminate layer and the foamed plastic of the body. Furthermore, the matrix can be adjusted by suitable measures so that it penetrates the body, forming an intermediate layer there that improves the bond between the laminate layer and the body. The circumferential groove-shaped depressions delimit partial areas of the surface with any desired contour.The circumferential groove-shaped depressions not only increase the surface area to increase the bonding forces between the laminate layer and the body, but also the flexural rigidity around the longitudinal axis, the transverse axis, and the vertical axis extending in the longitudinal direction of the device. Furthermore, by maintaining a constant or varying depth of the circumferential groove-shaped depression and by adjusting the surface area of ​​the partial surfaces defined by the circumferential groove-shaped depression, the flexural rigidity around the longitudinal axis, the transverse axis, and / or the vertical axis can be specifically adapted to the actual loads encountered. To increase the flexural rigidity, additional laminate layers can be applied to the first laminate layer.

[0064] Figure 9shows a process diagram for the production of a structural component with reinforcement made of a fiber-plastic composite, in particular a surfboard for stand-up paddling, surfing, windsurfing and the like. The process step S1 comprises providing a substantially board-like body made of foamed plastic, which is delimited by a surface and is completely covered with a fiber mat, in the present embodiment by a nonwoven fabric made of glass fibers. In a subsequent process step S2, the circumferential groove-shaped depressions are applied in a partial area of ​​the surface, wherein predetermined partial areas of the surface are delimited by the circumferential groove-shaped depressions. For this purpose, a matrix is ​​used, which in the present embodiment is sized to produce all of the circumferential groove-shaped depressions in one process step.Raised portions are formed on the die that correspond to the circumferential groove-shaped depressions to be applied. The die is placed on the fiber mat at the predetermined location so that the raised portions point toward the fiber mat. In a subsequent process step S3, the die is pressed against the fiber mat-body composite using a pneumatic cylinder with a predetermined force, and the die is heated to approximately 150°C using heating cartridges arranged in the die. At a lower die temperature, the depth of penetration of the die into the body of the fiber mat-body composite can be reduced. The temperature melts the plastic of the body and penetrates at least partially through the fiber mat. After the depressions have been applied, the die is removed from the fiber mat-body composite.In a further process step S4, the fiber mat is impregnated with matrix, covered with a peel ply, placed in a vacuum bag, and a predetermined negative pressure is created to allow the matrix to penetrate the fiber mat. The matrix can penetrate through the fiber mat and into the body, thus forming an intermediate layer adjacent to the surface of the body, in which the volume fraction of the matrix decreases with increasing distance from the surface up to a certain concentration. Once this concentration is reached, the matrix generally does not penetrate any deeper into the body. This process step is completed after the structural component has been removed and the peel ply removed. To reinforce the structural component, one or more laminate layers can be applied to the first laminate layer in a further process step S5.The recesses can be reproduced in the subsequent laminate layers or bridged. The at least one additional laminate layer can also be applied to only a portion of one of the laminate layers, for example, to increase the impact strength or the maximum permissible compressive load in certain areas. The optionality of process step S5 is indicated by a dashed arrow.

Claims

1. Device, in particular a surfboard for stand-up paddling, surfing, windsurfing and the like, having a body of foamed plastics material, wherein the body (12) is delimited by a surface (14) to which a fibre mat is non-releasably connected, characterized in that the surface (14) has at least in one sub-region (18) at least one encircling groove-shaped depression (20, 20', 20", 200, 210, 300, 300', 310, 310") by which a predetermined sub-area (22, 22', 22", 220, 222, 224, 320, 320") of the surface (14) is delimited, wherein the groove-shaped depression (20, 20', 20", 200, 210, 300, 300', 310, 310") is formed by heating the surface and pressing a die over the fibre mat into the heated surface of the body (12) in such a way that the fibre mat bears on the full area of the encircling groove-shaped depression (20) and that foamed plastics material has passed at least partially through the fibre mat.

2. Device according to Claim 1, characterized in that the first sub-area (22') having the first encircling groove-shaped depression (20') is contiguous to a second sub-area (22") having a second encircling groove-shaped depression (20").

3. Device according to Claim 2, characterized in that a predetermined portion (32, 302, 304) of the first encircling groove-shaped depression (20', 310) of the first sub-area (22', 320) forms a predetermined portion (36, 302, 304) of the second encircling groove-shaped depression (20", 310') of the second sub-area (22", 320') that is contiguous to the first sub-area (22', 320).

4. Device according to one of the preceding claims, characterized in that the sub-region (18) of the surface (14) has a multiplicity of sub-areas (22, 22', 22", 320, 320") which are delimited by encircling groove-shaped depressions (20, 20', 20", 300, 300', 310, 310") and are mutually contiguous, and in which predetermined portions (32, 302, 304) of the encircling groove-shaped depression (20', 310) of a sub-area (22', 320) are in each case formed by predetermined portions (36, 302, 304) of the encircling groove-shaped depression (20"", 310') of an adjacent sub-area (22", 320').

5. Device according to one of the preceding claims, characterized in that the encircling groove-shaped depression (310) is formed by a sequence of straight sections (302) or curved sections (304), or a mixture of straight sections (302) and curved sections (304).

6. Device according to Claim 5, characterized in that the encircling groove-shaped depression (22") has a contour of a hexagon (34) which has at least four respective first sides (36) which are of substantially identical length and lie opposite one another in pairs, and two second sides (38) which are of substantially identical length and lie opposite one another.

7. Device according to one of the preceding claims, characterized in that the encircling groove-shaped depression (20') is formed as a regular hexagon (30).

8. Device according to one of the preceding claims, characterized in that a depth (t, t'), by which the encircling groove-shaped depression (20) penetrates the body when measured from the surface (14) of the adjacent sub-area (22), is approximately 0.5 mm to approximately 15 mm, preferably approximately 2 mm to approximately 10 mm, and particularly preferably approximately 3 mm to approximately 5 mm.

9. Device according to one of the preceding claims, characterized in that the body (12) has a core (42) and an intermediate layer (40) which extends between the core (42) and the surface (14) and has a predeterminable thickness, wherein the intermediate layer (40) is filled with the matrix (26).

10. Device according to one of Claims 1 to 9, characterized in that a second laminate layer (44') of a fibre mat and a matrix is laminated on an upper side (41) of the laminate layer (16) extending on the surface (14) of the body (12), wherein a lower side of the second laminate layer (44') extends exclusively along the upper side (41) of the laminate layer (16) of the sub-areas in such a way that the upper side (46') of the second laminate layer (44') is flat.

11. Method for producing a device having a reinforcement of a fibre-plastics material composite, in particular a surfboard for stand-up paddling, surfing, windsurfing and the like, having a body of plastics material, wherein the body is delimited by a surface to which a fibre mat is non-releasably connected, characterized by applying the fibre mat to the body delimited by the surface, and subsequently forming at least one encircling groove-shaped depression at least in one sub-region of the surface by heating the surface and pressing a die onto the fibre-plastics material composite, wherein a predetermined sub-area of the surface is delimited by the encircling groove-shaped depression.

12. Method according to Claim 11, characterized by heating a die to a predetermined temperature, wherein the die has at least one elevation corresponding to the encircling groove-shaped depression.

13. Method according to Claim 12, characterized in that the die has all elevations corresponding to the encircling groove-shaped depressions.

14. Method according to Claim 12 or 13, characterized in that the predetermined temperature of the die is between approximately 90°C and approximately 220°C, preferably between approximately 120°C and approximately 180°C, and particularly preferably between approximately 140°C and approximately 160°C.