EP3568288A1

EP3568288A1 - Strand profile and method for producing a strand profile

Info

Publication number: EP3568288A1
Application number: EP18700155.7A
Authority: EP
Inventors: Gregor Daun; Christian KORFF; Jan Wucherpfennig; Diego Douglas D'AULIGNAC; Reinhard Jakobi; Helmut Schuermann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2017-01-10
Filing date: 2018-01-10
Publication date: 2019-11-20
Also published as: WO2018130561A1; US20190366617A1; CN110121407A

Abstract

What is proposed is a strand profile (10). The strand profile (10) extends in a direction of longitudinal extent (22), wherein the strand profile (10) has a first laminar structure (24) arranged around the direction of longitudinal extent (22) and a second laminar structure (32) surrounding the first laminar structure (24), wherein the first laminar structure (24) comprises a first plurality of layers (26), wherein each layer (26) of the first laminar structure (24) has multiple fibers (28), wherein the second laminar structure (32) comprises a second plurality of layers (34), wherein each layer (34) of the second laminar structure (32) has multiple fibers (36), wherein the fibers (28) of the first plurality of layers (26) and the fibers (36) of the second plurality of layers (34) respectively extend in directions of longitudinal extent (30, 38), wherein the directions of longitudinal extent (30) of the fibers (28) of the first plurality of layers (26) and of the fibers (36) of the second plurality of layers (34) are respectively oriented at an angle with a value in a range from 30° to 60°, and preferably in a range from 40° to 50°, relative to the direction of longitudinal extent (22) of the strand profile (10), wherein the fibers (28) of the first plurality of layers (26) extend relative to the direction of longitudinal extent (22) of the strand profile (10) such that, in the case of design torsion loading of the strand profile (10), they are loaded in longitudinal compression in their directions of longitudinal extent (30), wherein the fibers (36) of the second plurality of layers (34) extend relative to the direction of longitudinal extent (22) of the strand profile (10) such that, in the case of design torsion loading of the strand profile (10), they are loaded in longitudinal tension in their directions of longitudinal extent (38), wherein the directions of longitudinal extent (30) of the fibers (28) of adjacent layers (26) of the first plurality of layers (26) differ from one another by an angle with a value in a range from 0° to 10°, preferably 2° to 10° and more preferably 2° to 6°, wherein the directions of longitudinal extent (38) of the fibers (36) of adjacent layers (34) of the second plurality of layers (34) differ from one another by an angle with a value in a range from 0° to 10°, preferably 2° to 10° and more preferably 2° to 6°. Also proposed is a method for producing a strand profile (10).

Description

Extruded profile and method for producing an extruded profile

The present invention relates to an extruded profile and a method for producing an extruded profile.

Extruded profiles are used in many technical areas. So be

For example, in the automotive field, metallic extruded profiles are bent in the form of a helical spring. However, there is a need to reduce the weight of bent strand profiles. For example, there is a need to reduce the weight of springs for motor vehicles, thereby reducing the weight of the vehicle as a whole, which in turn can reduce the vehicle's energy consumption and emissions.

Weight can be reduced, for example, by using fiber-reinforced materials, so-called fiber composites. Fiber-reinforced materials contain as essential components fibers as reinforcing material and a matrix system or

Matrix material in which the fibers are embedded. Typically, the fibers are based on glass, carbon, aramid, polyacrylonitrile, polyester or polyamide. Thermosetting polymers, for example polyester resins, vinyl ester resins, polyurethane resins or epoxy resins, or thermoplastic polymers such as polyamides, polypropylenes or polyethylenes are usually used as the matrix system.

Various processes are known for the production of fiber-reinforced extruded profiles. In the typical pultrusion process, the fibers are unwound from bobbins, soaked in the matrix system or otherwise wetted, formed into the desired profile shape and cured. The fibers themselves may form the profile shape or they may be applied to a base body. The procedure will

Usually carried out continuously by the workpiece formed by the impregnated fibers is continuously pulled through the plant. In the so-called filament winding process, the fibers are also unrolled from bobbins and impregnated with the matrix system or otherwise wetted. By default, however, this is a discontinuous process in which a core or body to be coated rotates and the fibers are guided by an axial reciprocation on the workpiece and wound on this until the desired thickness of the fiber-plastic Layer is reached.

The so-called pull-winding method is a combination of pultrusion and filament winding process. A strand-shaped workpiece is pulled through the plant while fiber coils rotate about the workpiece, the fibers are soaked or wetted, and the wetted fibers are deposited on the workpiece. It can the

Wetting also only take place on the workpiece The strand-shaped workpiece can be a preformed basic body, for example a tube, but it can also be made by fibers are formed, which are brought in a first stage, for example in the pultrusion in a profile shape.

In general, such extruded profiles are produced by winding several layers of composite material around a core. The

Composite layers consist of fibers embedded in a polymer matrix. The extruded profile produced in this way can optionally be encased. Furthermore, the extruded profile can be bent, for example in the form of a helical spring. DE 38 24 933 A1 discloses a tubular, twistable spring element high specific load capacity, consisting of at least two concentric nested tubular bodies, which are formed at an angle between 0 ° and 90 ° extending fibers, wires, rods or slats, wherein the winding direction of the

Tubular body is in opposite directions and the inner tube body expands in torsional load in addition to the rotation and the outer tube body contracts, and the two tube body support each other at least from a defined torsional load. Between the tubular bodies an insulating, limited elastic layer is arranged; Furthermore, both tubular bodies are connected at their ends with a common force introduction part.

EP 0 145 810 A1 discloses an elastic wave composed of a plurality of coaxial layers consisting of parallel fibers, the fibers

Cross adjacent layers with each other. The shaft can be potted with plastic. In torsional stress all fibers of the shaft are subjected to tensile or compressive stress. The fiber arrangement can be chosen so that the fiber load is almost the same everywhere regardless of the layer diameter.

EP 0 637 700 A2 discloses a spiral spring of carbon fiber reinforced synthetic resin having a spirally wound cord made of carbon fiber reinforced synthetic resin, the carbon fibers being inclined at ± 30 ° to ± 60 ° with respect to

Axis of the cord are aligned. The ratio of the amounts of the carbon fibers A and B is 1.1 <A / B <4.0, where A is the amount of carbon fibers aligned in the direction in which a compressive force is applied in the longitudinal direction of the fibers, and B is the amount of carbon fibers aligned in the direction in which a tensile force is exerted in the longitudinal direction of the fibers.

JP 2006-226327 A discloses a fiber-reinforced plastic

A coil spring in which the spring material comprises a plurality of layers of fiber reinforced plastic impregnated with a fiber bundle of carbon fiber or carbon fiber resin impregnated around a straight core at predetermined angles in the same direction with respect to the axial direction of the core. US 5,603,490 A discloses fiber-reinforced plastic springs with helical fiber winding and, more particularly, a cylindrical torsion bar or coil with a core that is either unreinforced, axially fiber reinforced or twisted fiber reinforced, and a continuous fiber reinforced composite wrap covering most or all of them Fibers spirally arranged around the core. The core can be solid or hollow. The direction of the spiral winding is chosen to stress the fibers longitudinally when the spring is used as intended. A

A cladding fiber pitch of about 55 ° is used with a weak and unreinforced core, while larger or smaller pitch angles are used only with cores of sufficient rigidity to withstand axial normal stress.

WO 2014/014481 A1 discloses a composite coil spring which has a

Has screw body which extends along a helix axis. Of the

Screw body has a core and a plurality of fiber layers impregnated with a polymeric material. The plurality of fiber layers are disposed about the core at different radial distances from the helical axis. Each of the plurality of fiber layers extends around the helix axis at an acute angle to

Fiber axis. Each of the plurality of fiber layers comprises a number of fibers which is a product of a common base number of fibers multiplied by a non-zero positive integer from a set of nonzero positive integers. The positive nonzero integer of at least one of the plurality of fiber layers is different from the nonzero positive integer of at least one other of the plurality of fiber layers.

FR 2859735 A1 discloses a spring for motor vehicles comprising two or more layers of fibers wound in opposite directions around a core.

FR 2602461 A1 discloses a method for producing coil springs made of composite materials.

Despite the advantages brought about by the known extruded profiles and methods for their production, there is still a need for improvement. In particular, there is a need to further reduce the weight with otherwise identical or even improved qualitative properties.

It is therefore the task of developing known extruded profiles and methods for producing extruded profiles to the effect that the extruded profiles increased

Fatigue strength and have a reduced shear modulus.

This object is achieved by an extruded profile and a method having the features of the independent claims. Advantageous developments are specified in the dependent claims. A basic idea of the present invention is based on the finding that the necessary weight of an extruded profile and in particular of a coil spring on the material side can be further reduced by using materials with a higher shear strength and a lower shear modulus. A further basic idea of the present invention is to form the extruded profile with a thick-layered structure in which the fibers lie together in the pulling direction and the fibers in the compression direction, and in which there is a slight layerwise modulation of the fiber angle to the direction of extent within the fiber layers in the direction of tension and compression of the extruded profile by a mean angle. The fibers are preferably outside in the pulling direction.

An inventive extruded profile has a profile cross-section and extends along an axis, which may possibly also be bent. The direction of the axis is referred to as the longitudinal extension direction of the extruded profile. The extruded profile comprises a first layer structure arranged around the longitudinal extension direction of the extruded profile and a second layer structure surrounding the first layer structure. The first

Layer construction comprises a first plurality of layers, wherein each layer of the first layer structure comprises a plurality of fibers. The second layer construction comprises a second plurality of layers, each layer of the second layer structure comprising a plurality of fibers. The fibers of the first plurality of layers and the fibers of the second

A plurality of layers each extend in the longitudinal extension directions of the fibers. The longitudinal extension directions of the fibers of the first plurality of layers and the fibers of the second plurality of layers are each to the longitudinal direction of the extruded profile at an angle with an amount in a range of 30 ° to 60 °, and preferably in a range of 40 ° to 50 ° oriented. The fibers of the first plurality of layers extend in such a way relative to the longitudinal direction of the extruded profile, that they are subjected to longitudinal pressure in the longitudinal directions of extension of the extruded profile under nominal torsional loading. The fibers of the second plurality of layers extend in such a way relative to the longitudinal direction of the extruded profile, that they are claimed in the longitudinal direction of extension of the extruded profile in the longitudinal direction of extension of the extruded profile. The longitudinal extension directions of the fibers of adjacent layers of the first plurality of layers differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 ° of each other. The longitudinal extension directions of the fibers of adjacent layers of the second plurality of layers differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° of each other.

In the context of the present invention, an extruded profile is to be understood as meaning a workpiece which is formed by unwinding fibers, impregnating the fibers with at least one matrix material and shaping the fibers into a predetermined profile. The extruded profile is made in accordance with at least one fiber composite material. For example, the first layer structure and the second layer structure are made of produced different or identical fiber composites. In the context of the present invention, the extruded profile is in particular a workpiece produced by a pultrusion method, filament winding method or pull-winding method. However, it can also be made with another process such as winding preimpregnated fiber webs into tubes. The workpiece may be pre-cut to a certain length, but it may also be present as a tubular fabric initially indefinite length. The cross-sectional profile of the workpiece may be constant or variable over its length. The cross-sectional profile is limited only in that its greatest extent must be smaller than a cross-section of a through-hole of a

Device for producing the extruded profile. The workpiece can be hollow or compact.

In the context of the present invention, a longitudinal direction of extension means an extension in a direction parallel to the longest dimension of the respective component, such as, for example, the axis of the extruded profile, which may possibly also be bent, or the direction of the fibers.

In the context of the present invention, a layer is to be understood as meaning a uniform mass of areal extent with a specific thickness which is significantly smaller than the dimensions which form the areal extent.

In the context of the present invention, a layer structure is understood to mean a design or a construction in which a plurality of layers are arranged one above the other or in which several layers are arranged one above the other. For the purposes of the present invention, a fiber is understood to mean a linear, flexible, elementary structure which consists of a pulp and has an outer fiber shape which is thin in relation to its length. The fiber may be (quasi) endless or limited in length. Fibers can - without support by an enveloping matrix - in the longitudinal direction no compressive forces, but only absorb tensile forces, since they at

Kick pressure load.

In the context of the present invention, torsion means the effects of a force acting parallel to the base surface and tangential to the side surface of a body, which mainly turns the extruded profile about its longitudinal axis.

Under target torsional load is in the context of the present invention, a

To understand stress load of the extruded profile by torsion. In other words, the torsional load acts in a direction of rotation for which the

Extruded profile is designed to be loaded by torsion in this direction of rotation.

Accordingly, a structure for the extruded profile is proposed in which a first layer structure is surrounded to the outside by a second layer structure. Both the first layer structure and the second layer structure are made of several superimposed arranged layers formed. Each of the layers in turn has multiple fibers. Thus, the first layer structure is surrounded by the layers of the second

Layer structure. The turns or slopes of the fibers of the layers of the first layer structure differ from the turns or slopes to the fibers of the layers of the second layer structure. In other words, the fibers of the layers of the first layer structure are right-ascending and the fibers of the layers of the second layer structure are left-increasing or reverse-oriented. Accordingly, instead of a so-called fine-layered structure in which the layers with fibers

a coarse-layered structure is proposed, in which a first arrangement of layers with fibers of the same turn is provided one above the other, and then on this first arrangement a second arrangement of layers with fibers of the same turn is provided, wherein the turns of the Distinguish fibers of the first arrangement of the turns of the fibers of the second arrangement. Such a construction increases fatigue strength and reduces the shear modulus.

In addition, the orientations of the fibers of adjacent layers of the respective layer structure differ slightly from each other. In other words, the fibers of the respective layers of the first layer structure are not oriented parallel to each other, but intersect at a very acute angle in a plan view of the layers. Likewise, the fibers of the respective layers of the second layer structure are not oriented parallel to each other, but intersect at a very acute angle in a plan view of the layers. Such a structure acts to stop cracks. The second layer structure may comprise more fibers than the first layer structure.

Accordingly, more tensile, rather than compressive, fibers are provided. This can be realized by the second layer structure comprising more layers than the first layer structure, wherein the number of fibers per layer is identical. By such a structure, the extruded profile is more resilient to torsion.

For example, the number of fibers of the second plurality of layers is a factor of 1, 5 to 9, preferably 1, 5 to 4, more preferably 2 to 3 greater than the number of fibers of the first plurality of layers. As a result, a particularly stress on torsion extruded profile is obtained.

The first plurality of layers and the second plurality of layers may have different fiber volume fractions. The first plurality of layers may have a fiber volume fraction of 40% to 70% based on the volume of the first

Have layer structure to laterally support the longitudinally pressurized fibers in a stiff as possible composite material, and the second plurality of

Layers may have a fiber volume fraction of from 35% to 60% by volume of the second layer construction to accommodate the longitudinally tensioned fibers in To protect a relatively softer environment from the propagation of microcracks and anchorage by microcracks.

The fibers of the first plurality of layers may be embedded in a first matrix material. The fibers of the second plurality of layers may be embedded in a second matrix material. In this case, the second matrix material differs from the first matrix material. Thus, the first matrix material has a high rigidity with a tensile modulus of more than 2.9 GPa to laterally support the longitudinally pressurized fibers, whereas the second matrix material has high toughness to longitudinally lower Train set fibers to stop possible microcracks.

In the context of the present invention, a matrix material is to be understood as meaning any material which is suitable for fixing the fibers in their position after being deposited. Thermosetting polymers, for example polyester resins, are usually used as the matrix material.

Vinylesterharze, polyurethane resins or epoxy resins, or thermoplastic polymers such as polyamides, polypropylenes or polyethylenes are used, which are preferably high

Softening temperature, media resistance, fatigue resistance and simple

Processability agree.

The fibers of the first plurality of layers and the fibers of the second plurality of layers may be impregnated with different impregnating agents when the first

Layer structure of the second layer structure is separated by a layer for the impregnation impermeable layer from each other. Such a layer acts to stop cracks, so that a possible crack in the first layer structure can not spread to the second layer structure and vice versa.

In the context of the present invention, an impregnating agent is basically to be understood as meaning any matrix material which is cured by curing, for example by

Polymerization, for bonding the fibers and layers together and thus leads to a solidification of the fiber composite material. As impregnating agent in the context of the present invention, in particular a monomer or polymer-based liquid is used. In particular, the impregnating agent can be a liquid matrix material during processing, such as, for example, a reactive, liquid thermoset system based on, for example, polyurethane, polyester, vinyl ester, epoxy resin, or a reactive thermoplastic system based on caprolactam, polyacrylic, or a thermoplastic - Melt be based on polypropylene, polyethylene, polyamide, for example.

The fibers of the second layer structure may be formed as rovings with a filament diameter which is smaller than a filament diameter of the fibers of the first layer structure, since thereby in the region of the longitudinal direction to train

stressed fibers higher tensile strengths can be achieved. In the context of the present invention, a roving is to be understood as meaning a bundle, strand or multifilament yarn made of filaments arranged in parallel, that is, continuous filaments. For the purposes of the present invention, filaments produced from glass are preferably combined to form rovings, but other materials are also basically those in the art

Can be used within the scope of the present invention, such as aramid or carbon.

The extruded profile may have a core on which the first layer structure is arranged. The core may be an array of twisted fibers, a solid core, a jacketed solid core, a hollow core, or a jacketed hollow core.

In the context of the present invention, a core is to be understood as meaning a component or element which is provided for depositing the fibers. In other words, a core may be any component or element having a deposition surface on which fibers can be deposited.

In the case of twisted fibers, the fibers are twisted together. In principle, many types of cores can be used in the context of the present invention. The cross section of the core is preferably circular, but may in principle be oval, elliptical, polygonal or polygonal with rounded corners. A hollow core decreases in the

Compared to a solid core the weight.

The first layer structure preferably consists of the first plurality of layers, and the second layer structure consists of the second plurality of layers. This specifies a particularly permanently stable extruded profile.

The extruded profile can be bent. Thus, a higher variety of shapes is achieved.

The extruded profile can be bent in the form of a helical spring. Such a type of coil spring is permanently stable and of significantly less weight than coil springs made of metal or steel.

The helical spring may have at least one pitch H, a spring diameter D and a pitch angle a, where a ratio tan a = Η / (π ^* D) is not greater than 0.22 and preferably not greater than 0.21. Such a special geometry proves to be particularly durable, since the cross section of the extruded profile is stressed mainly by torsion and less by bending. It is explicitly emphasized that the pitch does not have to be constant over all turns of the coil spring, but may vary in different sections of the turns. For example, the pitch of the turns at the outer ends of the coil spring is smaller than in a central region of the coil spring.

The extruded profile can be designed as a clockwise-rotating compression spring or left-handed tension spring. The longitudinal extension directions of the fibers are the first A plurality of layers oriented to the right longitudinal to the longitudinal direction of the extruded profile at an angle in an amount in a range of 40 ° to 50 ° and the longitudinal extension directions of the fibers of the second plurality of layers are left to the longitudinal direction of the extruded profile at an angle in an amount in one Range oriented from 40 ° to 50 °. This combination of formation of the fibers in the first and second plurality of layers proves to be particularly good on torsion.

Alternatively, the extruded profile can be designed as a left-handed compression spring or right-handed tension spring. In this case, the longitudinal extension directions of the fibers of the first plurality of layers are oriented left to the longitudinal direction of the extruded profile at an angle in an amount in a range of 40 ° to 50 ° and the longitudinal extension directions of the fibers of the second plurality of layers are right-handed to the longitudinal direction of the extruded profile oriented at an angle with an amount in a range of 40 ° to 50 °. This combination of formation of the fibers in the first and second plurality of layers proves to be particularly good on torsion.

Preferably, the fibers of the first plurality of layers and the fibers of the second plurality of layers are glass fibers. Such fibers are particularly easy to process and permanently stable or have a high fatigue strength.

In the context of the present invention, a glass fiber is to be understood as meaning a long thin fiber made of glass. To produce thin threads are drawn from a glass melt.

An inventive method for producing an extruded profile, preferably an extruded profile as described above according to the invention, comprises:

(i) providing a core extending to define a longitudinal direction of the strand profile in a longitudinal direction,

(ii) arranging a first layer structure around the core, the first layer structure being formed from a first plurality of layers, each layer of the first layer structure having a plurality of fibers,

(iii) disposing a second layer structure around the first layer structure, wherein the second layer structure is formed of a second plurality of layers, each layer of the second layer structure comprising a plurality of fibers, wherein the fibers of the first plurality of layers and the fibers of the second plurality of layers each extend in the longitudinal extension directions, wherein the

Lengthwise directions of the fibers of the first plurality of layers and the fibers of the second plurality of layers respectively to the

Longitudinal direction of the extruded profile are oriented at an angle in an amount in a range of 30 ° to 60 ° and preferably in a range of 40 ° to 50 °, wherein the fibers of the first plurality of layers so relatively extend to the longitudinal direction of the extruded profile, that they are subjected to longitudinal compressive stress in the longitudinal extension directions at nominal torsional load of the extruded profile, wherein the fibers of the second plurality of layers extend relative to the longitudinal direction of the extruded profile that they at nominal torsional load of the extruded profile in their

Longitudinal directions are claimed on longitudinal train, wherein the longitudinal extension directions of the fibers of adjacent layers of the first

A plurality of layers at an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 ° of each other

differ, wherein the longitudinal extension directions of the fibers adjacent

Differentiate layers of the second plurality of layers by an angle having an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 °, and

(iv) removing the core or leaving the core in the first layer construction.

Accordingly, a method for producing the extruded profile is proposed with a structure in which there is a core in the interior, which is surrounded in a direction outward by a first layer structure and then by a second layer structure. Both the first layer structure and the second layer structure are formed from a plurality of layers arranged one above the other. Each of the layers in turn has multiple fibers. Thus, the core is outwardly surrounded first by the layers of the first layer structure and then by the layers of the second layer

In addition, the orientations of the fibers of adjacent layers of the respective layer structure differ slightly from each other. In other words, the fibers of the respective layers of the first layer structure are not oriented parallel to each other, but intersect at a very acute angle in a plan view of the layers. Likewise, the fibers of the respective layers of the second layer structure are not oriented parallel to each other, but intersect at a very acute angle in a plan view of the layers. Such a structure acts to stop cracks. If the core is removed, the weight of the extruded profile is further reduced. If the core remains, this can stabilize the extruded profile.

The second layer structure may be formed with more fibers than the first layer structure. Accordingly, more tensile, rather than compressive, fibers are provided. This can be realized by the second layer structure comprising more layers than the first layer structure, wherein the number of fibers per layer is identical. Alternatively, however, it is also possible to specifically vary the number of fibers per layer and / or the fiber volume fraction per layer. By such a structure, the extruded profile is more resilient to torsion. In other words, such a structure shifts the crack formation boundary toward higher torsion loads.

The number of fibers of the second plurality of layers may be greater than the number of fibers of the first plurality of layers by a factor of 1, 5 to 9, preferably 1, 5 to 4, particularly preferably 2 to 3. This is a particularly resilient to torsion

Extruded profile provided.

The first plurality of layers and the second plurality of layers may be formed with different fiber volume fractions, wherein the first plurality of layers has a fiber volume fraction of 40% to 70% based on the volume of the first layer structure, the second plurality of layers having a

Having fiber volume fraction of 35% to 60% based on the volume of the second layer structure. Within the first and second plurality of layers, the

Fiber volume fraction can also be slightly varied in order to match the carrying percentage of individual layers to each other.

The fibers of the first plurality of layers may be embedded in a first matrix material and the fibers of the second plurality of layers may be embedded in a second matrix material. In this case, the second matrix material may differ from the first matrix material. The first matrix material may have a high rigidity with a tensile modulus of more than 2.9 GPa, and the second matrix material may have a high toughness.

The fibers of the first plurality of layers and the fibers of the second plurality of layers may be impregnated with a different impregnating agent when the first layer structure is separated from the second layer structure by a layer impermeable to the impregnating agent. Such a layer acts to stop cracks, so that a possible crack in the first layer structure can not spread to the second layer structure and vice versa.

The fibers of the second layer construction may be formed as rovings having a filament diameter smaller than a filament diameter of the fibers of the first layer structure. The core may be an array of twisted fibers, a solid core, a jacketed solid core, a hollow core, or a jacketed hollow core. In principle, many types of cores can be used in the context of the present invention. The cross section of the extruded profile is preferably circular, but may be basically, oval, elliptical, polygonal or polygonal with rounded corners. A hollow core reduces the weight compared to a solid core.

The first layer structure may consist of the first plurality of layers and the second layer structure may consist of the second plurality of layers. This specifies a particularly fatigue-resistant or fatigue-resistant extruded profile.

The fibers of the first layer structure and / or the fibers of the second layer structure can be arranged by means of filament winding or by means of pull-winding. So that the fibers can be arranged very precisely aligned.

The method may further include bending the strand profile. Thus, a higher variety of shapes is achieved. The method may further comprise bending the extruded profile in the form of a helical spring. Such a type of coil spring is highly durable or fatigue-proof and of significantly less weight than coil springs made of steel.

The helical spring may have at least one pitch H, a spring diameter D and a pitch angle a, where a ratio tan a = Η / (π * D) is not greater than 0.22 and preferably not greater than 0.21. Such a special geometry proves to be particularly durable or fatigue-proof.

The extruded profile may be formed as a right-handed compression spring or left-handed tension spring, wherein the longitudinal extension directions of the fibers of the first plurality of layers are oriented right-handed to the longitudinal direction of the extruded profile at an angle in an amount in the range of 40 ° to 50 °, wherein the longitudinal extension directions of Fibers of the second plurality of layers are oriented left to the longitudinal direction of the extruded profile at an angle in an amount in a range of 40 ° to 50 °. This formation of the fibers in the first and in the second plurality of layers proves to be particularly good on torsion.

Alternatively, the extruded profile may be formed as a levorotatory compression spring or a clockwise directional spring, the longitudinal extension directions of the fibers of the first plurality of layers being oriented left to the longitudinal direction of the extruded profile at an angle in an amount in a range of 40 ° to 50 °, the longitudinal extension directions the fibers of the second plurality of layers right-handed to the longitudinal direction of the extruded profile at an angle in an amount in be oriented in a range of 40 ° to 50 °. This formation of the fibers in the first and in the second plurality of layers proves to be particularly good on torsion. The fibers of the first plurality of layers and the fibers of the second plurality of layers are preferably glass fibers. Such fibers are particularly easy to process and have a high fatigue strength.

According to the invention, an extruded profile is proposed which is obtained or obtainable according to one of the methods described above. This makes it possible to produce the extruded profile with the advantages of the method described above.

According to the invention, the use of a previously described extruded profile is proposed as a spring in a chassis of a motor vehicle. This can be used in the motor vehicle, a spring that is relatively low in weight and yet operational.

The invention will be explained in more detail below with reference to the drawings. The drawings are to be understood as schematic representations. They do not constitute a limitation of the invention, for example with regard to specific dimensions or

Design variants.

1 shows a side view of an extruded profile,

FIG. 2 shows a side view of an extruded profile according to a first embodiment,

FIGS. 3A to 3E each show a plan view of the first layer structure and examples of possible orientations of the fibers of the first layer structure,

FIG. 4 shows a side view of an extruded profile according to a second embodiment,

FIG. 5 shows a side view of an extruded profile according to a third embodiment,

FIG. 6 shows a side view of an extruded profile according to a fourth embodiment,

FIGS. 7A to 7D show various steps of a method for producing an extruded profile, FIG. 8 shows results for the shear modulus, the shear strength and the ratio of

Shear modulus to the squared shear strength,

FIG. 9 shows the transmittable shear stress T _max as a function of tan a and. Figure 10 shows the yieldable shear stress T _max for two types of laminates in springs with similar profile and different chemistry for the materials used.

Detailed description of the embodiments

Figure 1 shows a side view of an extruded profile 10 which is bent in the form of a clockwise helical spring 12. Accordingly, the extruded profile 10 is wound in a clockwise direction about an axis of symmetry 14. For purposes of explanation, certain characteristics of the coil spring 12 are shown in FIG. The coil spring 12 has a

Outside diameter d _{e of} the extruded profile 10. The extruded profile 10 may be tubular and thus have an inner diameter d. The coil spring 12 also has a pitch H, a spring diameter D and a pitch angle a. The slope H is defined as the distance from centers of adjacent turns in a direction parallel to the axis of symmetry 14. The spring diameter D is as a distance from centers of adjacent turns in a direction perpendicular to

Symmetry axis 14 defined. The pitch angle a is defined as an angle between a center line 16 of the extruded profile 10 and a plane 18 perpendicular to the axis of symmetry 14.

FIG. 2 shows a side view of an extruded profile 10 according to a first embodiment of the present invention. The extruded profile 10 is in the form of a clockwise

Helical spring 12 bent. The coil spring 12 has a slope H, a

Spring diameter D and a pitch angle a, wherein a ratio tan a = Η / (π * D) is not greater than 0.22 and preferably not greater than 0.21. The coil spring 12 is a right-handed compression spring, as indicated by arrows 20. The extruded profile 10 extends in a longitudinal extension direction 22. The extruded profile 10 has one around the

Longitudinal direction 22 arranged first layer structure 24. The first

Layer structure 24 has a first plurality of layers 26, of which only one is indicated in FIG. The first layer structure 24 preferably consists of the first plurality of layers 26. Each layer 26 of the first layer structure 24 has a plurality of fibers 28. The fibers 28 of the first plurality of layers 26 each extend in the longitudinal extension directions 30. The longitudinal extension directions 30 of the fibers 28 of the first plurality of layers 26 are each to the longitudinal extension direction 22 of the extruded profile 10 at an angle with an amount in the range of 30 ° 60 ° and preferably oriented in a range of 40 ° to 50 °. The fibers 28 of the first plurality of layers 26 extend so relative to the longitudinal extension direction 22 of FIG

Extruded profile 10, that they at target torsional load of the extruded profile 10 in their

Longitudinal directions 30 are claimed on longitudinal pressure. In the first

Embodiment, the longitudinal extension directions 30 of the fibers 28 of the first plurality of layers 26 are right-handed to the longitudinal extension direction 22 of FIG

Extruded profile 10 at an angle with an amount in the range of 40 ° to 50 ° oriented. The extruded profile 10 furthermore has a second layer structure 32 surrounding the first layer structure 24. The second layer structure 32 has a second plurality of

Layers 34, of which only one is indicated in Figure 2. The second layer structure 32 preferably consists of the second plurality of layers 34. Each layer 34 of the second layer structure 32 has a plurality of fibers 36. The fibers 36 of the second

The plurality of layers 34 each extend in the longitudinal extension directions 38. The longitudinal extension directions 38 of the fibers 36 of the second plurality of layers 34 are each to the longitudinal direction 22 of the extruded profile 10 at an angle in an amount in the range of 30 ° to 60 ° and preferably in a range of 40 ° to 50 ° oriented. The fibers 36 of the second plurality of layers 34 extend in such a way relative to the longitudinal direction 22 of the extruded profile 10 that they are subjected to longitudinal tension in the longitudinal directions of extension of the extruded profile 10 in the longitudinal direction of extension. In the first embodiment, the

Longitudinal directions 38 of the fibers 36 of the second plurality of layers 34 oriented left-handed to the longitudinal direction 22 of the extruded profile 22 at an angle with an amount in the range of 40 ° to 50 °.

The fibers 28 of the first plurality of layers 26 and the fibers 36 of the second

Multiple layers 34 are glass fibers. The second layer structure 32 comprises more fibers 36 than the first layer structure 24. Thus, the number of fibers 36 of the second plurality of layers 34 is greater by a factor of 1.5 to 9, preferably 1.5 to 4, more preferably 2 to 3 the number of fibers 28 of the first plurality of layers 26. The first plurality of layers 26 and the second plurality of layers 34 have different fiber volume fractions. Thus, the first plurality of layers 34 has a fiber volume fraction of 50% to 70% relative to the volume of the first

Layer structure 24 and the second plurality of layers 34 has a

Fiber volume fraction of 35% to 60% based on the volume of the second layer structure 32 on. The fibers 28 of the first plurality of layers 26 are embedded in a first matrix material. The fibers 36 of the second plurality of layers 34 are embedded in a second matrix material. The second matrix material is optionally different from the first matrix material. In the case of different matrix materials, the first matrix material has a high rigidity with a tensile modulus of preferably more than 2.9 GPa and the second matrix material has a high toughness. The fibers 28 of the first plurality of layers 26 are impregnated with a first impregnating agent and the fibers 36 of the second plurality of layers 34 are impregnated with a second impregnating agent. The first layer structure 24 is optionally separated from the second layer structure 32 by a layer impermeable to the first impregnating agent and the second impregnating agent. The first impregnating agent is different from the second impregnating agent. The fibers 36 of the second layer structure 32 are formed as rovings having a filament diameter that is optionally smaller than a filament diameter of the fibers 28 of the first layer structure 24. Optionally, the extruded profile 10 may have a core on which the first

Layer structure 24 is arranged. The core may be an array of twisted fibers, a Solid core, a sheathed solid core, a hollow core or a sheathed hollow core. The core can remain in the finished workpiece or be removed.

In the extruded profile 10, the longitudinal directions 30 of the fibers 28 of adjacent layers 26 of the first plurality of layers 26 differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° from each other. In addition, the longitudinal directions 38 of the fibers 36 of adjacent layers 34 of the second plurality of layers 34 differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 °. This will be explained below with reference to the first

Layer structure 24 explained in more detail, wherein the explanations for the second layer structure 32 apply analogously.

Figures 3A to 3E each show a plan view of the first layer structure 24 and examples of possible orientations of the fibers 28 of the first layer structure 24. Shown by way of example only are a first layer 26a, a second layer 26b, and a third layer 26c of the first layer structure 24 in the order given

are arranged one above the other. The first layer 26a has a first plurality of fibers 28a. The second layer 26b has a second plurality of fibers 28b. The third layer 26c has a third plurality of fibers 28c. Of the fibers 28a, 28b, 28c, only one is shown for reasons of clarity. Alternatively, in the case of only two layers, the fibers 28a and 28c may vary about an imaginary line of symmetry having the profile of the fiber 28b. In Figure 3A, the second plurality of fibers 28b extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° clockwise to the first plurality of fibers 28a. In addition, the third plurality of fibers 28c extend to the second plurality of fibers 28b at an angle of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° in the clockwise direction.

In Figure 3B, the second plurality of fibers 28b extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° counterclockwise to the first plurality of fibers 28a. In addition, the third plurality of fibers 28c extend to the second plurality of fibers 28b at an angle of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° counterclockwise.

In Figure 3C, the second plurality of fibers 28b extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° clockwise to the first plurality of fibers 28a. In addition, the third plurality of fibers 28c extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 ° counterclockwise, to the first plurality of fibers 28a. In Figure 3D, the second plurality of fibers 28b extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 ° counterclockwise, to the first plurality of fibers 28a. In addition, the third plurality of fibers 28c extend at an angle of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 ° clockwise, to the first plurality of fibers 28a.

It is understood that the respective angles need not be identical in their amount.

FIG. 3E shows an arrangement in which the fibers 28a, 28c of each second layer 26a, 26c of the same layer structure 24 extend parallel to each other.

Accordingly, the fibers 28a, 28c overlap in the plan view of FIG. 3E.

FIG. 4 shows a side view of an extruded profile 10 according to a second

Embodiment of the present invention. Below are only the

Differences from the first embodiment described and the same components are provided with the same reference numerals. The extruded profile 10 is bent in the form of a left-handed helical spring 12. The coil spring 12 is a left-handed compression spring, as indicated by arrows 20. In the second embodiment, the

Longitudinal stretching 30 of the fibers 28 of the first plurality of layers 26 oriented left-handed to the longitudinal direction 22 of the extruded profile 10 at an angle with an amount in a range of 40 ° to 50 °. In addition, in the second embodiment, the longitudinal extension directions 38 of the fibers 36 of the second plurality of layers 34 are oriented right-handed to the longitudinal extension direction 22 of the extruded profile 22 at an angle with an amount in a range of 40 ° to 50 °.

FIG. 5 shows a side view of an extruded profile 10 according to a third embodiment of the present invention. Hereinafter, only the differences from the first embodiment will be described, and like components are given the same reference numerals. The extruded profile 10 is bent in the form of a clockwise helical spring 12. The coil spring 12 is a right-handed tension spring, as indicated by arrows 20. In the third embodiment, the longitudinal extension directions 30 of the fibers 28 of the first plurality of layers 26 are left-handed

Longitudinal direction 22 of the extruded profile 10 at an angle with an amount in the range of 40 ° to 50 ° oriented. In addition, in the third embodiment, the longitudinal extension directions 38 of the fibers 36 of the second plurality of layers 34 are oriented right-hand to the longitudinal direction 22 of the extruded profile 22 at an angle with an amount in a range of 40 ° to 50 °.

FIG. 6 shows a side view of an extruded profile 10 according to a fourth embodiment of the present invention. Hereinafter, only the differences from the first embodiment will be described, and like components are given the same reference numerals. The extruded profile 10 is bent in the form of a left-handed helical spring 12. The coil spring 12 is a left-handed tension spring, as indicated by arrows 20. In the fourth embodiment, the longitudinal directions 30 of the fibers 28 of the first plurality of layers 26 are oriented to the right longitudinal to the longitudinal direction 22 of the extruded profile 10 at an angle with an amount in the range of 40 ° to 50 °. In addition, in the fourth embodiment, the longitudinal directions 38 of the fibers 36 of the second plurality of layers 34 are left-handed with respect to FIG

Longitudinal direction 22 of the extruded profile 22 at an angle with an amount in the range of 40 ° to 50 ° oriented.

Hereinafter, a method for producing a strand profile 10 will be described. The method is described with reference to a production of an extruded profile 10 according to the first embodiment. However, the method is also suitable for producing an extruded profile according to the second to fourth embodiments.

FIGS. 7A to 7D show different steps of the method. As shown in Figure 7A, a core 40 is first provided. The core 40 extends to define the longitudinal extension direction 22 of the extruded profile 10 in a longitudinal direction. The core 40 extends straight, for example. The core 40 may be an array of twisted fibers, a solid core, a jacketed solid core, a hollow core, or a jacketed hollow core. As shown in FIG. 7B, the core 40 is around the

Longitudinal direction 22 of the first layer structure 24 is arranged. The first

Layer structure 24 has the first plurality of layers 26. Preferably, the first layer structure 24 consists of the first plurality of layers 26. Each layer 26 of the first layer structure 24 has a plurality of fibers 28, of which only one is shown in FIG. 7B. The fibers 28 can be arranged on the core 40, for example by means of filament winding. The fibers 28 of the first plurality of layers 26 each extend in longitudinal directions 30. The longitudinal directions 30 of the fibers 28 of the first plurality of layers 26 are respectively to the longitudinal extension direction 22 of the extruded profile 10 at an angle in an amount in the range of 30 ° 60 ° and preferably oriented in a range of 40 ° to 50 °. The fibers 28 of the first

A plurality of layers 26 extend in such a way relative to the longitudinal direction 22 of the extruded profile 10 that they are subjected to longitudinal compression under nominal torsional loading of the extruded profile 10 in their longitudinal extension directions 30. In the embodiment shown, the longitudinal extension directions 30 of the fibers 28 of the first plurality of layers 26 are right-handed to the longitudinal extension direction 22 of FIG

Extruded profile 10 at an angle with an amount in the range of 40 ° to 50 ° oriented.

As shown in FIG. 7C, the second layer structure 32 is arranged on the first layer structure 24 surrounding it. The second layer structure 32 has the second plurality of layers 34. Preferably, the second layer structure 32 consists of the second plurality of layers 34. Each layer 34 of the second layer structure 32 has a plurality of fibers 36, of which only one is shown in FIG. 7C. For example, the fibers 36 may be disposed on the first layer structure 24 by filament winding or pull-winding become. The fibers 36 of the second plurality of layers 34 each extend in the longitudinal extension directions 38. The longitudinal extension directions 38 of the fibers 36 of the second plurality of layers 34 are each to the longitudinal extension direction 22 of the extruded profile 10 at an angle in an amount in the range of 30 ° 60 ° and preferably oriented in a range of 40 ° to 50 °. The fibers 36 of the second plurality of layers 34 extend in such relative to the longitudinal direction 22 of the extruded profile 10 that they at nominal torsional load of the extruded profile 10 in their

Longitudinal directions 38 are claimed on longitudinal train. In the first

Embodiment, the longitudinal extension directions 38 of the fibers 36 of the second plurality of layers 34 are left-handed to the longitudinal extension direction 22 of FIG

Extruded profile 22 oriented at an angle with an amount in a range of 40 ° to 50 °.

Multiple layers 34 are glass fibers. The second layer structure 32 comprises more fibers 36 than the first layer structure 24. Thus, the number of fibers 36 of the second plurality of layers 34 is greater by a factor of 1.5 to 9, preferably 1.5 to 4, more preferably 2 to 3 the number of fibers 28 of the first plurality of layers 26. The first plurality of layers 26 and the second plurality of layers 34 may have different fiber volume fractions. Thus, the first plurality of layers 34 has a fiber volume fraction of 40% to 70% based on the volume of the first layer structure 24 and the second plurality of layers 34 has one

Fiber volume fraction of 35% to 60% based on the volume of the second layer structure 32 on. The fibers 28 of the first plurality of layers 26 are embedded in a first matrix material. The fibers 36 of the second plurality of layers 34 are embedded in a second matrix material. The second matrix material may be different from the first matrix material. Thus, the first matrix material may have a high rigidity and the second matrix material may have a high toughness. The fibers 28 of the first plurality of layers 26 and the fibers 36 of the second plurality of layers 34 are each impregnated with an impregnating agent. The first layer structure 24 may be separated from the second layer structure 32 by a layer impermeable to the impregnant layer. The impregnating agents may differ from each other. The fibers 36 of the second layer structure 32 are formed as rovings having a filament diameter that may be smaller than a filament diameter of the fibers 28 of the first layer structure 24.

In the extruded profile 10, the longitudinal extension directions 30 of the fibers 28 of adjacent layers 26 of the first plurality of layers 26 differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° from each other. Moreover, the longitudinal extension directions 38 of the fibers 36 of adjacent layers 34 of the second plurality of layers 34 differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 °, and more preferably 2 ° to 6 °, as described above. Subsequently, the core 40 be removed or remain in the first layer structure 24. Removal of the core 40 is possible, for example, if the core 40 is made of PTFE, since this material does not stick to the matrix system of the fiber composite material. As shown in Figure 7D, the extruded profile 10 is then bent. The extruded profile 10 is bent, for example in the form of a clockwise-rotating coil spring 12, for example by means of a freeform tool. The coil spring 12 is formed with a pitch H, a spring diameter D and a pitch angle a, wherein a ratio tan a = Η / (π * D) is not greater than 0.22 and preferably not greater than 0.21. Subsequently, the coil spring 12 is cured, which can be done with heat.

EXAMPLES The invention will be explained in more detail with reference to the following examples.

For the examples below, the following nomenclature used in determining the experimental results is used. B exponential fatigue strength

C ratio DI d _e

de extruded profile outside diameter

di extruded profile inside diameter

D spring diameter

F force

G shear modulus averaged

H slope of the spring coil

k ratio di / d _e

K spring constant

n number of vibrations to break

N number of spring coils

a pitch angle of the spring coil

δ deflection of the spring from the unloaded position

öB.max Bending stress at the horizontal outer edge of the extruded profile cross-section

T _S shear stress due to shear

τ _τ Shear stress due to torsion on the extruded profile circumference with radially increasing

tension

T _{M AX} Increased shear stress at the inner circumference of a thick spring due to torsion and shear, calculated according to Waals

p density For the geometry of the coil spring, the following relationship between slope H,

Spring diameter D and pitch angle a:

H

tan (a) = -

As can be deduced from the standard literature on the design of coil springs, stresses on torsion, bending and shear stress are exerted on the cross-section of a hollow helical spring when the axial force is applied.

Shear stress:

Bending stress around the spring axis:

° ^B ' ^{max =} nd l - k *)

Shear stress by torsion at the outer edge with radial stress curve:

8 FD

^{TT =} 7T df (l - fc ⁴ )

For springs made of thick rods or extruded profiles results in an increased shear stress on the inner circumference of the spring coil due to torsion and shear, which is approximated by Waals with:

8 F D 4 C - 1 0.615 \

= nd _e ³ (l - k *) UC - 4 ^{+ ~} ΊΓ)

Endurance tests are often reported as Wöhler lines according to the following equation:

10 ⁶ ) = τ {η) (- ^) ^ß

The deflection of the spring is calculated as

8 FD ³ N

~ G d * (l - / c ⁴ )

The spring constant is the local slope of the force as a function of the deflection:

AF

Conversely, the required shear modulus can be determined from the slope:

8 D ³ N

G ^{= K} d (l - The mass of a coil spring results from the requirements of the permissible force and desired deflection at this force as a function of the three material characteristics

Shear modulus, density and shear strength:

1 p G

m = 2 - FS

1 + k ² τ _τ ²

To minimize the mass m in a spring, it is necessary to develop laminates, ie layer structures, with a low shear modulus G and a high shear strength τ _τ .

We examined right-handed coil springs under pressure with the dimensions D = 99.5 mm, d _e = 19.5 mm, d, = 10.0 mm. The slope was generally flatter at the two ends, as is common with coil springs for the automotive industry. Table 1 shows the slope of the turns in the shaping. The pitch of the spring pads is listed. The slope H is given in mm in Table 1. In the first line, the numerical values indicate turns sections, where the number 1 indicates one complete turn or 360 °.

Table 1

Laminate: The laminate construction of the individual samples was fine-grained (F) or coarse (G) with different ratios of the fibers subjected to pressure in their longitudinal direction to the fibers loaded in their longitudinal direction. In this case, fine-layered means an alternating arrangement of the layers of different directions of rotation and coarse-layer means that only a plurality of layers with fibers of the same direction of rotation and then a plurality of layers with fibers of opposite or deviating

Direction of rotation is applied. Thus, in Table 2 in the first column sample variants are given, which have different laminate or layer structures, wherein the laminate or layer structures are given in the second column. The number of pressure-loaded layers and then the number of layers loaded with tension are indicated in the first column in the brackets first. Thus, for example, F (3/7) means a fine-layered structure with three pressure-loaded and seven tensile layers. The exact structure of the layers is given in the second column, where (-) a

Orientation or an angle to the longitudinal extension direction of the extruded profile for pressure-loaded layers and (+) an orientation or an angle to

Longitudinal direction of the extruded profile for zugbelastetet layers indicates. Table 2

The following materials were used for the tested extruded profiles. The

Glass fiber was a roving weighing 2400 g / km (2400 tex). System A consisted of the resin bisphenol A diglycidyl ether with 22 wt .-% butanediol diglycidyl ether and the hardener diethylmethylbenzene diamine in the mixing ratio 100: 26. System B consisted of the resin bisphenol A diglycidyl ether with 22 wt.% Butanediol diglycidyl ether and the curing agent dicyanamide (56% by weight) + methylcyclohexyl-diamine (26% by weight) + 3,3 '- (4-methyl-1,3-phenylene) bis (1,1-dimethylurea), available under the trade name Uron Dyhard UR500, (18% by weight) in a mixing ratio of 100: 1 1. The fiber mass fraction was calculated using the amount of glass material, core material, auxiliary materials used and the total weight of profiles for system A at 67% +/- 2% and for system B determined at 65% +/- 2%.

The spring bars were made with filament winding with 8 threads per layer with a multiple ring thread eye. Wrapped on a 7 mm steel core encased in a polyethylene hose with 10 mm outer diameter and 1 mm wall thickness, which has no significant effect on the strength and rigidity of the springs. The steel core was pulled after filament winding. The spring bars were placed on a tube of 80 mm

Outer diameter wound. The slope in the molding process was adjusted by spacers. The cure of System A was at 120 ° C for 2 hours and at 150 ° C for 5 hours. The cure of System B was at 90 ° C for 3 hours and at 140 ° C for 1 hour. The laminates were not only different loadable, but also different torsional stiffness. Therefore, the tests for fatigue strength of a minimum

Holding force of 1000 N up to the highest possible force until just before the block set of the spring driven, depending on the laminate 3 - 5 kN were. The frequency was 3.5 1 / s. Thus, with a force F, a number of cycles n up to the break was determined.

The key figures for comparing the laminates were calculated as follows: From

Spring characteristic F (5), the slope K was determined at a mean deflection of 55 mm. The shear modulus G was determined from this slope assuming that 4 free turns could twist during this deflection. The highest torsional stress and maximum shear stress at the number of cycles n was determined as:

8 F D

τ _τ (η) =

d | (l - / c ⁴ )

8 F D 4 C - 1 0.615 \

nd (1-W V4 C - ⁺ C)

With an experimentally determined exponent B = 0.05, the permissible torsional stress and maximum shear stress at 1 million cycles were determined for comparison of the laminates: τ _Γ (10 ⁶ ) = τ _Γ () ( _Ί ^) ^Β

6) ( ⁷¹ ₆ j ^B

^T max (10 - T _max (l)

FIG. 8 gives the results thus determined for the shear modulus, the sustainable one

Shear stress at 1 million cycles and the ratio of shear modulus to sustainable shear stress in square.

The results in Figure 8 show the superiority of these laminates under torsional loading. In particular, the ratio G / τ _Τ ² , which is proportional to the necessary spring mass, decreases from the value of the fine-layered standard laminate F (5/5) to 55%, which is a

Weight saving compared to this standard laminate of 45% allows.

However, with increasing slope H or increasing pitch angle a, the bending stress in the extruded profile also increases. The extruded profile can no longer be optimized exclusively for torsion. FIG. 9 shows the transmittable shear stress T _max as a function of tan a. Figure 9 shows that in a high pitch spring design, H is higher

Bending stresses the torsion-optimized laminate cuts off worse.

Table 3 shows the comparison of shear strength and partly shear modulus for

different laminates for two different epoxy systems.

Table 3

^* Experiment ends without spring break Figure 10 shows the transmittable shear stress T _max for two types of laminate in springs with a similar profile and different chemistry for the materials used. More precisely, in FIG. 10, the transmittable shear stress T _max for an extruded profile in the form of

Standard laminate F (5/5) prepared with the chemistry according to systems A and B described above and for an extruded profile with a construction G according to the invention (3/7) prepared with the chemistry according to systems A and B described above. From FIG. 10 it can be seen that the transmittable shear stress T _max for the extruded profile with a construction G according to the invention (3/7) is higher than for the extruded profile in the form of standard laminate F (5/5), the chemistry used having a negligible influence the transmittable shear stress i _max has. With reference to FIG. 10, the advantageous effect on the transmittable shear stress T _{max can} be clearly seen on the basis of the present invention.

Claims

claims

1. extruded profile (10), wherein the extruded profile (10) in a longitudinal direction of extension (22), wherein the extruded profile (10) extends around the longitudinal direction

(22) arranged first layer structure (24) and a first layer structure (24) surrounding the second layer structure (32),

wherein the first layer structure (24) comprises a first plurality of layers (26), each layer (26) of the first layer structure (24) comprising a plurality of fibers (28), the second layer structure (32) comprising a second plurality of layers (34 ), each layer (34) of the second layer structure (32) having a plurality of fibers (36),

wherein the fibers (28) of the first plurality of layers (26) and the fibers (36) of the second plurality of layers (34) each extend in longitudinal directions (30, 38), wherein the longitudinal extents (30) of the fibers (28) the first

A plurality of layers (26) and the fibers (36) of the second plurality of layers (34) each to the longitudinal direction (22) of the extruded profile (10) at an angle in an amount in the range of 30 ° to 60 ° and preferably in are oriented in a range of 40 ° to 50 °,

wherein the fibers (28) of the first plurality of layers (26) are so relative to the

Longitudinal direction (22) of the extruded profile (10) extend that they are subjected to longitudinal stress in the longitudinal direction of extension (30) in the case of nominal torsional loading of the extruded profile (10),

wherein the fibers (36) of the second plurality of layers (34) extend relative to the longitudinal extension direction (22) of the extruded profile (10) in such a way as to provide

Desired torsional load of the extruded profile (10) are claimed in their longitudinal directions of extension (38) on longitudinal train,

wherein the longitudinal extension directions (30) of the fibers (28) of adjacent layers (26) of the first plurality of layers (26) are at an angle in the range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° apart,

wherein the longitudinal extension directions (38) of the fibers (36) of adjacent layers (34) of the second plurality of layers (34) are at an angle in the range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° apart.

2. An extruded profile (10) according to claim 1, wherein the second layer structure (32) comprises more fibers (36) than the first layer structure (24), wherein in particular the number of fibers (36) of the second plurality of layers (34) around a Factor 1, 5 to 9, preferably 1, 5 to 4, more preferably 2 to 3 is greater than the number of fibers (28) of the first plurality of layers (26).

An extruded profile (10) according to claim 1 or 2, wherein the fibers (28) of the first plurality of layers (26) are impregnated with a first impregnating agent and the fibers (36) of the second plurality of layers (34) are impregnated with a second impregnating agent wherein the first layer structure (24) is preferably separated from the second layer structure (32) by a layer impermeable to the first impregnating agent and the second impregnating agent, preferably wherein the first impregnating agent is different from the second impregnating agent.

The extruded profile (10) according to any one of claims 1 to 3, wherein the extruded profile (10) has a core (40) on which the first layer structure (24) is arranged, wherein the core (40) comprises an array of twisted fibers Solid core, a sheathed solid core, a hollow core or a sheathed hollow core is.

5. extruded profile (10) according to one of claims 1 to 4, wherein the extruded profile (10) is bent in the form of a coil spring (12), wherein in particular the helical spring (12) has a pitch H, a spring diameter D and a pitch angle a, wherein a ratio tan a = Η / (π ^* D) is not greater than 0.22 and preferably not greater than 0.21.

6. extruded profile (10) according to claim 5, wherein the extruded profile (10) is designed as a clockwise-rotating compression spring or left-handed tension spring, wherein the

Longitudinal extension directions (30) of the fibers (28) of the first plurality of layers (26) are oriented right-handed to the longitudinal direction (22) of the extruded profile (10) at an angle with an amount in a range of 40 ° to 50 °, the longitudinal extension directions (38) the fibers (36) of the second plurality of layers (34) are oriented left-handed to the longitudinal extension direction (22) of the extruded profile (10) at an angle in an amount in a range of 40 ° to 50 ° or

wherein the extruded profile (10) as a left-handed compression spring or clockwise

Tension spring is formed, wherein the longitudinal extension directions (30) of the fibers (28) of the first plurality of layers (26) left to the longitudinal direction (22) of the extruded profile (10) at an angle in an amount in a range of 40 ° to 50 ° wherein the longitudinal extension directions (38) of the fibers (36) of the second plurality of layers (34) are oriented to the longitudinal direction (22) of the extruded profile (10) at right angles to the longitudinal direction (22) at an angle in the range of 40 ° to 50 ° are.

The extruded profile (10) according to any one of claims 1 to 6, wherein the fibers (28) of the first plurality of layers (26) and the fibers (36) of the second plurality of layers (34) are glass fibers.

8. A method for producing an extruded profile (10), preferably an extruded profile (10) according to one of claims 1 to 7, comprising: (i) providing a kernel (40) suitable for defining a

Longitudinal direction (22) of the extruded profile (10) in one

Extends longitudinal direction,

(ii) placing a first layer structure (24) around the core (40), the first layer structure (24) being formed from a first plurality of layers (26), each layer (26) of the first layer structure (24) comprising a plurality of fibers (28),

(iii) arranging a second layer structure (32) around the first layer structure (24), wherein the second layer structure (32) is formed from a second plurality of layers (34), each layer (34) of the second

Layer structure (32) has a plurality of fibers (36), wherein the fibers (28) of the first plurality of layers (26) and the fibers (36) of the second plurality of layers (34) each extend in longitudinal extension directions (30, 38) wherein the longitudinal extension directions (30, 38) of the fibers (28) of the first plurality of layers (26) and the fibers (36) of the second plurality of layers (34) at an angle to the longitudinal extension direction (22) of the extruded profile (10) are oriented in an amount in a range of 30 ° to 60 ° and preferably in a range of 40 ° to 50 °, wherein the fibers (28) of the first plurality of layers (26) are so relative to the longitudinal direction (22) of the Extruded profiles (10) extend that they are subjected to longitudinal pressure under nominal torsional loading of the extruded profile (10) in their longitudinal extension directions (30), the fibers (36) of the second plurality of layers (34) being so relative to the longitudinal extent gsrichtung (22) of the extruded profile (10) extend that they at nominal torsional load of the extruded profile (10) in their

Longitudinal directions (38) are claimed on longitudinal train, wherein the longitudinal extension directions (30) of the fibers (28) adjacent

Layers (26) of the first plurality of layers (26) differ by an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° apart, wherein the

Longitudinal directions (38) of the fibers (36) of adjacent layers (34) of the second plurality of layers (34) at an angle in an amount in a range of 0 ° to 10 °, preferably 2 ° to 10 ° and more preferably 2 ° to 6 ° apart,

(iv) removing the core (40) or leaving the core (40) in the first one

Layer structure (24).

The method of claim 8, wherein the second layer structure (32) is formed with more fibers (36) than the first layer structure (24), wherein in particular the number of fibers (36) of the second plurality of layers (34) by a factor of 1, 5 to 9, preferably 1, 5 to 4, more preferably 2 to 3 is greater than the number of fibers (28) of the first plurality of layers (26). The method of claim 8 or 9, wherein the fibers (28) of the first plurality of layers (26) are impregnated with a first impregnating agent and the fibers (36) of the second plurality of layers (34) are impregnated with a second impregnating agent, wherein the first layer structure (24) is preferably separated from the second layer structure (32) by a layer impermeable to the first impregnating agent and the second impregnating agent, preferably wherein the first impregnating agent is different from the second impregnating agent.

Method according to one of claims 8 to 10, further comprising bending the extruded profile (10) in the form of a helical spring (12), wherein in particular the

Coil spring (12) has a pitch H, a spring diameter D and a

Slope angle a, wherein a ratio tan a = Η / (π ^* D) is not greater than 0.22 and preferably not greater than 0.21.

The method of claim 1 1, wherein the extruded profile (10) as dextrorotatory

Compression spring or left-handed tension spring is formed, wherein the

Longitudinal directions (30) of the fibers (28) of the first plurality of layers (26) are oriented right-handed to the longitudinal direction (22) of the extruded profile (10) at an angle with an amount in a range of 40 ° to 50 °, wherein the longitudinal extension directions (38) the fibers (36) of the second plurality of layers (34) are oriented left-handed relative to the longitudinal extension direction (22) of the extruded profile (10) at an angle in an amount in a range of 40 ° to 50 ° or

Tension spring is formed, wherein the longitudinal extension directions (30) of the fibers (28) of the first plurality of layers (26) to the left to the

Longitudinal extension direction (22) of the extruded profile (10) are oriented at an angle with an amount in a range of 40 ° to 50 °, wherein the

Longitudinal directions (38) of the fibers (36) of the second plurality of

Layers (34) are oriented to the right longitudinal to the longitudinal direction (22) of the extruded profile (10) at an angle in an amount in the range of 40 ° to 50 °.

13. The method according to any one of claims 8 to 12, wherein the fibers (28) of the first

A plurality of layers (26) and the fibers (36) of the second plurality of layers

(34) are glass fibers.

14. extruded profile (10), obtained or obtainable according to a method according to any one of claims 8 to 13.

15. Use of an extruded profile (10) according to any one of claims 1 to 7 or according to claim 14 as a spring in a chassis of a motor vehicle.