EP2247222A1

EP2247222A1 - Support structure and method for the production and use of such a support structure

Info

Publication number: EP2247222A1
Application number: EP09712815A
Authority: EP
Inventors: Herbert Börger
Original assignee: Thermoplast Composite GmbH
Current assignee: Covestro Thermoplast Composite GmbH
Priority date: 2008-02-23
Filing date: 2009-02-16
Publication date: 2010-11-10
Anticipated expiration: 2029-02-16
Also published as: SI2247222T1; WO2009103474A1; EP2247222B1; DE102008010869A1; ATE544376T1

Abstract

The invention relates to a support structure (1) having a core (2). Said core comprises natural or wood fibers (3) embedded in an acrylate resin. A jacket (5) of the core (2) is made of a fiber-reinforced plastic. The core (2) has a density along the support structure (1) that varies by more than 10%. The result is a support structure, which can be adjusted to predetermined load requirements in a defined manner.

Description

Support structure and method for producing and using such a support structure

The invention relates to a support structure according to the preamble of claim 1. Furthermore, the invention relates to a method for producing such a support structure and to a use of such a support structure.

Support structures of the type mentioned are known from DE-PS 1 1 19 503, DE 298 16 638 Ul and DE 84 32 781 Ul. Further supporting structures are known from DE 100 60 379 A1 and DE 10 2006 023 865 A1.

The adaptation of the known support structures to the current load requirements is in need of improvement.

It is an object of the present invention to develop a support structure of the type mentioned in such a way that it can be defined to adapt to predetermined load requirements.

This object is achieved by a support structure with the features specified in claim 1.

According to the invention, it has been recognized that a compound of natural or wood fibers with acrylate resin offers the possibility of predetermining the core density via a compression of such a core in the as yet uncured state. The wood fibers of the support structure according to the invention may be wood fibers which have been freed from a binding matrix. The wood starting material can be derived from the cellulose fibers of the Partially or practically completely liberated wood binding lignin. The compound of the natural or wood fibers with the acrylate resin can be done by embedding the fibers in the resin. Alternatively, the acrylate resin can also be used as a binder between the natural or wood fibers. The support structure can therefore be equipped, where it is exposed to greater loads, with a denser and thus more resilient core. After pressing, there is no elastic recovery of the fiber material, but after pressing there is a permanent, plastic deformation and thus a correspondingly predetermined density of the core. On the one hand, the covering contributes to increasing the load-carrying capacity of the support structure and, on the other hand, protects the core from the penetration of moisture. The sheath is preferably made of an organic sheet, ie of a thermoplastic high-performance fiber composite plastic. In the sheath fibers may be used in the form of endless or spun and in particular highly oriented glass fibers, natural fibers, synthetic fibers or carbon fibers. A polymer matrix of the fiber reinforced plastic of the enclosure may be selected from a suitable thermoplastic material, for example polypropylene, polyamide, a thermoplastic polyester or a blend of different polymers. Here, polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethersulfone, acrylonitrile-butadiene-styrene (ABS), acrylic ester-styrene-acrylonitrile (ASA) or styrene-acrylonitrile (SAN) can be used. The acrylate resin used as matrix for the core fibers in particular Aerodur® BASF AG can be used. Preferred is a formaldehyde-free resin as a fiber matrix for the core. Even after pressing, the core made of the natural or wood fibers remains sufficiently porous so that the matrix of the fiber-reinforced plastic forming the cladding penetrates into these pores for the intimate connection of the cladding with the core can. As natural fibers, in addition to wood fibers, for example, seed fibers such as cotton, bast fibers such as hemp, jute, linen or ramie, other resin fibers such as sisal or manila or fruit fibers such as coconut can be used. The varying core density along the support structure causes the support structure in the longitudinal direction can be well adapted to changing load conditions. In the case of a carrier, for example, the core density in the region of force introduction points or fastening sections can be purposefully increased. For example, crossmembers loaded centrally from above may have a higher density in the center than at the edge. As far as a support structure according to the invention is used as a functional component, the density of the core is adapted to the respective load conditions of this functional component. The result is the possibility of an easily and inexpensively executable support structure.

An acrylate resin content according to claim 2 gives a particularly good loadable core.

A continuous density variation according to claim 3 allows an optimized density adjustment of the core, so that it is actually amplified only in the areas that require such a gain due to the loading requirements. Upon reaching predetermined load requirements, an optimally lightweight support structure is achieved in this way.

A graduated density variation according to claim 4 facilitates the manufacture of the support structure.

A core density range according to claim 5 has been found to be particularly well suited for many practical loading requirements. Vorzugswei- - A -

The core density varies between 450 g / l and 850 g / l, more preferably between 500 g / l and 1000 g / l. Typical moduli of elasticity resulting from these density ranges are between 1,750 MPa and 3,100 MPa. Bending stress values σ, _{for example,} lie at values between 18 MPa and 31 MPa for these density ranges.

A cross-sectional variation of the support structure according to claim 6 allows an additional geometric adaptation to the respective load requirements.

Fiber lengths according to claim 7 have been found to be particularly suitable for achieving a durable and resilient core. The fibers have a typical diameter in the range between 10 microns and 150 microns. Depending on the flow behavior of the acrylate resin, very thin fibers, for example with a fiber diameter between 10 .mu.m and 30 .mu.m, or strong fibers, for example with a diameter in the range between 100 .mu.m and 150 .mu.m, may be preferred.

An enclosure according to claim 8 has surprisingly been found to be sufficient to ensure the required in practice for the support structure according to the invention additional load absorption and protective effect by the enclosure. The wrapper may have a thickness of 0.8 mm.

An enclosure according to claim 9 allows an additional load adjustment along the support structure over the envelope thickness.

A wrapper according to claim 10 is an inexpensive variant of a wrapper of varying thickness. A supporting structure according to claim 11 combines the advantages of a load-bearing structure matched by the covering thickness with those of a supporting structure of constant external cross-section. As wrapping, for example, laminate thicknesses adapted to the strength of the load can be used. The support structure can be used wherever a varying outer cross-section would interfere, especially where space is scarce or where good stackability of the support structure is required. In addition, this allows a cost-effective continuous production of the support structure as in particular endless profile strand.

A constant basis weight core layer according to claim 12 may have an over-the-plane load-bearing capacity over a varying density perpendicular to the plane in which the constant basis weight exists or over a sheath thickness varying in that plane. The support structure can be used wherever it represents a ballast that must not exceed a given weight per unit area.

A hollow chamber design according to claim 13 increases the surface of the core, which can be used advantageously for Kemtrocknung after molding of this. In the Hohlkammeraus leadership, the envelope can be done in particular at the same time with a shaping Kernverpressung. This reduces the production cost.

Separate core sections according to claim 14 provide a further degree of freedom for load adjustment of the support structure. Where a higher load has to be absorbed, several, for example, juxtaposed core sections can be provided. The core sections may in particular have different lengths. Another object is to specify a production method for the support structure according to the invention. This object is achieved by the method according to claims 15 and 16.

According to the invention, it has been recognized that a density variation for the support structure according to the invention can be specified exactly by stacking prepregs, that is to say natural or wood fibers preimpregnated with the uncured acrylate resin. Depending on the density and depending on the dimensions of the individual prepregs forming the stack, a defined density variation results after pressing

Supporting structure. The wrapping of the core produced by the compression is usually carried out after the pressing.

In the alternative manufacturing method according to claim 16, the desired density variation is generated via a corresponding variation of the basis weight of the fiber mat. The two methods according to claims 15 and 16 can also be combined with each other. For example, a fiber mat of continuously varying basis weight may be part of a prepreg stack.

In the method according to claims 15 and 16, the envelope may be designed to be plastically deformable, so that the envelope, for example, variably compensates a cross-sectional variation of the core over a longitudinal dimension of the support structure. In the method according to claims 15 and 16, the prepreg stack can be crimped in a single step to the core of the support structure. The pressing temperature of the prepreg stack may be greater than 150 ⁰ C, greater than 200 ⁰ C and may for example be 250 ⁰ C. In this case, the temperature of the pressing tool can be significantly lower than the temperature of the prepreg stack and can, for example, be lower than 150 ⁰ C, lower than 100 ⁰ C and may be, for example 7O ⁰ C.

Uses according to claim 17 exemplify the advantages of a load-adapted density variation of the core of the support structure. In the case of a slat for a slatted frame, the center of the slat in particular has an increased core density, so that the slat is particularly resistant to bending in its center. In addition, it is possible to provide several types of battens with different maximum stiffnesses, matching the required stiffnesses in the shoulder and pelvic region on the one hand, and in the head and foot region of a slatted frame, on the other hand. These different types of slats can be provided with identical dimensions, so that only one type of slat shots needs to be used regardless of the type of slat used. In a ski, this is equipped in particular in the binding area with increased core density. This increased core density can be generated, for example, by increased lateral compression in the production of the core of the support structure in the region of the sidecut. This ensures that, especially in the bond area, the core density is increased due to the stronger compression. Alternatively or additionally, a ski may be equipped in a fastening region, for example for bonding with increased core density. In this case, an additional prepreg layer can be placed exactly before pressing where it is intended to screw the binding to the main body of the ski. In the area of this increased core density, a sufficient pull-out force can be provided without additional measures, so that fastening screws can be screwed directly into this fastening area. In the case of a hockey stick, this is particularly pronounced in the area of the trowel and in the region of the transition from the trowel to the handle carrier with increased core density. leads. Other sports rackets can also be designed with the support structure according to the invention, for example tennis rackets, squash rackets, badminton rackets or even golf clubs. In a boot paddle especially the paddles themselves and the transitions between the paddles and the handle bar are designed with increased core density. In the case of a property developer, what has already been stated above in connection with the support structure according to the invention applies accordingly.

Embodiments of the invention will be explained in more detail with reference to the drawing. In this show:

Figure 1 is a longitudinal section through a slat of a slatted frame for a bed frame as an example of a erfϊndungsgemäßen support structure.

2 shows a cross section along line II-II in Fig. 1.

Fig. 3 is a diagram showing a density along the support structure of Fig. 1;

FIG. 3 a in a representation similar to FIG. 3 a variant of a density variation along the slat according to FIG. 1; FIG.

4 shows a perspective longitudinal section through a ski as a further example of a support structure according to the invention;

Fig. 5 stacked prepreg layers as an intermediate step in the manufacture of the support structure of Fig. 4;

Fig. 6 is a graph showing a density along the ski of Fig. 4 in a similar manner to Fig. 3; 7 shows a side view of a hockey stick as a further example of a supporting structure according to the invention;

8 shows a section along line VIII-VIII in Fig. 7.

9 shows a section along line IX-IX in Fig. 7 .;

Fig. 10 is a diagram of a density along the hockey stick after

Fig. 7 in a similar to Figure 3 representation.

11 shows a longitudinal section through a developer as another example of a support structure according to the invention;

FIG. 12 shows a section according to line XII-XII in FIG. 11; FIG.

Fig. 13 in a similar to Fig. 12 representation of a section through a

Support structure in the form of a developer with a core extending axially in the hollow chamber;

14 is a view similar to FIG. 12, showing a cross-section through another embodiment of a ski as a further example of a support structure according to the invention cut in a binding section;

15 shows a further cross section through the embodiment of Figure 14 in the region of a portion spaced from the binding portion. 16 shows a cross section through stacked prepreg layers as an intermediate step in the production of a further embodiment of a ski as a further example of a support structure according to the invention; and

Fig. 17 also in cross-section a core of the ski embodiment of Fig. 16 with the compressed prepreg stack and an associated diagram illustrating the density across the width of the ski.

Fig. 1 shows a bar 1 of a bedframe otherwise not shown for a bed frame. The bar 1 is shown in a longitudinal section. A

Longitudinal axis of the bed frame is perpendicular to the plane of Fig. 1. The bar 1 represents a first example of a support structure according to the invention.

The lath 1 has a core 2, which in Fig. 1 schematically by a

Hatching represented natural or wood fibers 3, which are embedded in a matrix of acrylate resin 4. The core 2 has a content of acrylate resin 4 in the range between 8% by weight and 25% by weight. The natural or wood fibers 3 have a length in the range between 3 and 30 mm and a diameter in the range between 10 μm and 150 μm.

The core 2 has a sheath 5 made of a fiber-reinforced plastic. The envelope 5 has along the bar 1 a constant thickness U of about 0.8 mm. The entire bar 1 has in the sectional plane of Fig. 1 has a thickness L of about 8 mm.

The core 2 has a length along the bar 1 by more than 10% varying density. The core 2 is divided in Fig. 1 from left to right in a total of six sections I, II, III, IV, V and VI. The two middle sections Along the slat 1 are the sections III and IV. The two end-side sections are the sections I and VI. Between the end and the middle sections are the sections II and V. The sections II to V have an approximately equal longitudinal extent. In contrast, the end sections I and VI are somewhat longer.

In the end sections I and VI, the core 2 has a density of 575 g / l. In the middle sections III and IV, the core 2 has a density of 810 g / l. In between, ie in sections II and V, the core 2 has a density of 690 g / l. The density of the core 2 thus varies in steps between sections I and II, II and III, IV and V, and V and VI, respectively.

The slat 1 is made as follows:

First, a stack of multiple layers of a acrylate resin impregnated natural or wood fiber prepreg is provided. Where there should be a higher density of the core 2 along the slat 1, there is also a higher number of prepreg layers in this provision. In sections III and IV, for example, there are three prepreg layers. In Sections II and V two prepreg layers are present. In Sections I and VI, a prepreg sheet is present. Subsequently, the stack thus provided is pressed to the core 2 of the support structure and in turn subsequently wrapped with the sheath 5. During pressing, the acrylate resin is pressed through gaps between the natural or wood fibers in the unpressed state. In this way, the prepregs can be formed plastically. The prepreg layers have a temperature of 25O ⁰ C during pressing. The pressing tool has a temperature of 7O ⁰ C during pressing. Instead of a graded density variation of the core 2, as shown in FIG. 3, there may also be a continuous density variation of the core 2, as shown in FIG. 3a.

In this case, the density varies from the left end of the slat 1 in FIG. 1, starting from a value of about 300 g / l up to a value in the middle of the slat 1 according to FIG. 1 at 800 g / l, and then increases until in 1 right end of the bar 1 again to a value of 300 g / l. This variation is approximately cosinusoidal about a center along the batten 1.

A continuous density variation according to FIG. 3 a can likewise be produced with the aid of a prepreg stack, with the individual prepreg layers running towards the end in each case in the shape of a wedge, ie decreasing in their thickness linearly towards their ends. Alternatively, continuous density variation can be achieved by using a fiber mat as a core-making material, the fiber mat having a continuously varying basis weight according to the desired density variation.

A further variant of a supporting structure according to the invention using the example of a ski will be explained below with reference to FIGS. 4 to 6. Components which correspond to those already explained above with reference to FIGS. 1 to 3 bear the same reference numerals and will not be discussed again in detail. The ski 6 has a tip portion I, a binding portion III and an end portion V. Between the tip portion I and the binding portion III and between the binding portion III and the end portion V, there is a transition portion II and IV, respectively. The ski has a varying cross section over its length. In this case, both the thickness of the core 2 perpendicular to a contact plane of this and the width of the core 2 varies along the ski 6. The thickness variation is such that the ski 6 is the thickest in the binding section III, the strength of the ski 6 to Shovel and towards the end continuously decreases. The width of the ski 6 varies in such a way that it is waisted, ie it is the least wide in the binding section III.

FIG. 5 shows a stack of natural or wood fiber prepregs 7, 8, 9, 10 prepared in preparation for the ski 6. The prepregs 7 to 10 have an acrylate resin content of 13%. The prepreg 7 represents the basis of the stack, which covers the entire length of the ski 6. The prepregs 8, 9 are each made shorter and serve to form the transition sections of the ski 6. The prepreg 10 is present only in the binding section III. The starting thickness of the stacked prepregs 7 to 10 is such that, after the compression of the prepregs, they have been densified most in the region of the binding section III, so that the highest density of the core 2 is present there. The course of the core density is shown in FIG. 6, which is similar to FIG. In the tip section I and in the end section V, a density in the range of about 600 g / l is present. Transition sections II and IV have two density ranges with a lower density of about 650 g / L and a higher density of about 700 g / L. Bonding Section III has a density of about 850 g / l.

A further variant of a support structure according to the invention using the example of a hockey stick 11 will be explained with reference to FIGS. 7 to 10. Components which correspond to those which have already been explained above with reference to FIGS. 1 to 6 bear the same reference numerals and will not be explained again in detail. The hockey stick 11 is divided into a total of four sections, namely a trowel section I, a handle section IV and two transition sections II and III. A center of gravity 12a of the hockey stick 11 lies in the middle of the transitional section II. The cross-sectional shapes of the trough section I and of the grip section IV illustrate the two cross-sectional views of FIGS. 9 and 8, respectively.

The prepreg preparation before pressing the core 2 of the hockey stick 11 is such that there are four prepreg layers in the trowel section I, one prepreg layer in the grip section IV and three or two prepreg layers in the transition sections II and III. In the trough portion I results in a density of the core 2 of 850 g / l (see Fig. 10). In Transition Section II, a core 2 density of 790 g / l results. In the transitional section III results in a density of the core 2 of 690 g / l. In the grip section IV, a density of the core 2 of 610 g / l results.

With reference to FIGS. 11 and 12, a developer 12 will be explained below as a further example of a support structure according to the invention. Components corresponding to those already described above with reference to Figs. 1 to 10 bear the same reference numerals and will not be discussed again in detail.

The developer 12 has an enclosure 13 with a length along the developer 12 varying strength. This thickness is twice as large in a middle section II of the developer 12 as in a left-hand section I in FIG. 11 or in a right-hand section III in FIG. 11. The envelope 13 is formed by a fiber-reinforced plastic laminate, which is designed in section II double-layered. A second layer 14 of the sheath 13 is inwardly in this double-layered section II, that is, offset to the core 2. The prepregs, which form the core 2, all have the same length in the developer 12, which coincides with the length of the developer 12, and the same strength. When pressing this forming the core 2 prepregs, the second layer 14 works in the outer prepreg layers, so that the core 2 in Section II receives an increased density, without that in the area II compared to the areas I and III an increased number present at prepreg layers.

In a plane 15a which is horizontal and perpendicular to the plane of the drawing in FIG. 11, the core 2 has a constant weight per unit area. In area II, the density of the core 2 of the developer 12 is about 900 g / l. In regions I and III, the density of the core 2 is about 600 g / l.

The developer 12 has outer walls 15, 16, which are smooth throughout, so without steps executed.

FIG. 13 shows, in a cross-sectional view similar to FIG. 12, the developer 12 in an alternative embodiment to FIGS. 11 and 12. The core 2 of the developer 12 according to FIG. 13 has a central hollow chamber 17 extending along the developer 12, that is perpendicular to the plane of the drawing according to FIG. 13. The core 2 is also located behind the chamber wall 18, which delimits the hollow chamber 17 Applying the sheath 5 free and is accessible via at least one end of the developer 12 of FIG. 13 after applying the sheath 5.

A support structure 12 having a hollow chamber, as shown in FIG. 13, can be produced in such a way that a sheathing through the sheath 5 takes place simultaneously with a shaping of the core 2 taking place by means of compression. The sheath 5 and the core 2 are then in the support structure produced at the same time. Water or water vapor, which forms during the compression of the core 2, can then be discharged via the hollow chamber 17 to the outside of the support structure, so that a drying of the core 2 is possible. Such drying can be assisted, for example, by passing dry air or another drying medium through the hollow chamber. After drying of the core 2, the hollow chamber 17 can be closed to the end, so that an undesirable absorption of water of the core 2 is prevented.

14 to 17 show further cross-sections of support structures or prepreg layers as an intermediate step of their production, wherein these cross-sectional design can be used for the support structure in the application example "ski." Components corresponding to those described above with reference to FIG have been explained to the embodiments of Figs. 1 to 13, bear the same reference numerals and will not be discussed again in detail.

A ski 19 according to FIGS. 14 and 15 has a core 2 which is designed in several parts. A central core portion 20 is in the binding portion of the ski 19 before and has a rectangular cross-section. In FIG. 14 right and left of the central core section 20, there are two lateral core sections 21. The lateral core sections extend in the longitudinal direction of the ski 19, ie perpendicular to the plane of the drawing in FIGS. 14 and 15, not only beyond the binding section, but also beyond the binding section on both sides thereof. This is illustrated by the further cross-sectional illustration of the ski 19 according to FIG. 15, which shows a cross section outside the binding section. There are only the lateral core portions 21, but not the central core portion 20 before. In the transverse 15, the ski 19 is embodied between the two lateral core sections 21 as a plate section 22, which can be embodied completely from the material of the covering 5, for example.

Fig. 16 shows stacked prepreg sheets 23, 24, 25, 26, 27, 28, 29 in a schematic instantaneous view of an intermediate step in the manufacture of another embodiment of a ski as an example of a support structure. The prepreg layers 23 to 29 are numbered from left to right in FIG. 16. In FIG. 16, to the right, the width dimension b of the ski to be produced extends. In FIG. 16, the height dimension h of the ski to be produced, ie its thickness perpendicular to the support plane, extends upwards. The prepreg layers 23 to 29 are all made of the same material, as explained above, for example in connection with Prepregs 7 to 10. The prepreg layers 23 to 29 all have the same density. The prepreg layers 23 to 29 are arranged in preparation for the pressing so that in FIG. 16 they are all flush down to a plane 30 which coincides with the support plane of the ski to be produced. The prepreg layers 23, 25, 27 and 29 have a greater height extent compared to the prepreg layers 24, 26, 28 respectively disposed between two of these prepregs.

After pressing the prepreg layers 23 to 29 stacked according to FIG. 16, a core 2 which is generally rectangular in cross section is present as an intermediate product of the ski to be produced. The prepreg layers 23, 25, 27, 29 with in the initial state of greater height are more compressed than the other prepreg layers 24, 26, 28. After pressing therefore results in a graded density variation across the width b of the core 2, in 17 is shown at the top in a p (b) diagram. At the place of the higher prepreg Layers 23, 25, 27, 29 each have a higher density than between them.

The core 2 is then provided with an envelope, as already explained above in connection with the other embodiments.

With regard to its loading capacity and its weight, the core produced according to FIGS. 16 and 17 has properties which are comparable to those of a conventionally manufactured ski with a uniform core density, in which longitudinal grooves have been milled on the upper side. A corresponding milling waste can therefore be avoided in the embodiment of FIGS. 16 and 17.

Claims

claims

A support structure (1; 6; 11; 12; 19) comprising a core (2) containing natural or wood fibers (3) joined together by an acrylate resin and a cladding (5) of a fiber-reinforced one Plastic, characterized in that the core (2) has a density which varies along the support structure (1; 6; 11; 12) by more than 10%.

2. Support structure according to claim 1, characterized in that the core a portion of the acrylate resin (4) in the range between

8% by weight and 25% by weight.

3. Support structure according to claim 1 or 2, characterized by a continuous density variation of the core (2).

4. Support structure according to claim 1 or 2, characterized by a stepped density variation of the core (2).

5. Support structure according to one of claims 1 to 4, characterized in that the density of the core (2) in the range between 300 g / l and 1100 g / l varies.

6. Support structure according to one of claims 1 to 5, characterized by a varying cross section in the longitudinal direction.

7. Support structure according to one of claims 1 to 6, characterized in that the natural or wood fibers (3) have a length in the range between 3 mm and 60 mm.

8. Support structure according to one of claims 1 to 7, characterized in that the sheath (5) has a thickness (U) which is less than 1 mm.

9. supporting structure according to one of claims 1 to 8, characterized by a sheath (5) with a longitudinally of the support structure (1; 6; 11;

12) varying strength.

10. Support structure according to claim 9, characterized by a multi-layer enclosure (13, 14).

11. Support structure according to claim 9 and 10, characterized in that along this in areas of the thickness of the sheath (13. 14), an outer cross section of the support structure (12) is constant.

12. Support structure according to one of claims 1 to 11, characterized in that the core (2) in a longitudinal axis of the support structure (12) containing plane (15a) has a constant weight per unit area.

13. Support structure according to one of claims 1 to 12, characterized in that the core (2) extends along the support structure (12).

, having extending hollow chamber (17).

14. Support structure according to one of claims 1 to 13, characterized in that the core (2) has at least two separate core sections (20, 21).

15. A method for producing a support structure (1; 6; 11; 12; 19) according to one of claims 1 to 14, comprising the following steps:

Providing a stack of several layers of one with the acrylate

Resin (4) impregnated natural fiber / wood fiber prepregs (7 to 10), wherein there, where along the support structure (1; 6; 11; 12) should have a higher density of the core (2), a higher number

Prepreg layers is present,

Pressing the prepreg stack to the core (2) of the support structure

(1; 6; 11; 12)

Enveloping the core (2) with the envelope (5).

16. A method for producing a support structure (1; 6; 11; 12; 19) according to one of claims 1 to 14, comprising the following steps:

Providing a fiber mat with a surface weight varying according to the desired density of core density in the longitudinal direction of the support structure to be produced,

Pressing the fiber mat to the core (2) of the support structure, wrapping the core (2) with the sheath (5).

17. Use of a support structure according to one of claims 1 to 14 as - lath (1) of a slatted frame for a bed frame,

- skis (6; 19), hockey sticks (1 1), boot paddles,

- Property developer (12).