Connection means between the load introduction element and the fibre plastic composite component

Abstract

The invention relates to a connection device (1) having an elongate load introduction element (2) with a truncated conical subregion (13) and a fiber-plastic composite component (3) with a cylindrical opening (4), the load introduction element (2) being pressed into the opening in a pressing direction (7) and, in the opening, at least three trapezoidal-prismatic base elements (5) with one base (9) and two congruent base faces (8.1) being arranged in a spaced-apart manner along a circular intersection line (13) of an inner face (12) of the opening (4) and the truncated conical subregion (14) of the load introduction element (2), so that one of the base faces (8.1) of the base elements (5) is directed in the pressing direction (7) and the base (9) of the base elements (5) lies against the inner face (12), wherein between two base elements (5) a wedge-shaped trapezoidal-prismatic pressure element (6) is arranged, so that a pressure base (15) which is formed in correspondence with the truncated conical subregion (14) of the load introduction element (2) is directed towards the load introduction element (2) and a thickness (7) which is formed perpendicular to the pressure base (15) increases in the pressing direction (7), wherein a reversible surface pressure is formed between the base elements (5) and the pressure elements (6) and between the truncated conical subregion (14) and the pressure base (15), the strength of the surface pressure increasing the deeper the load introduction element (2) is pushed into the fiber-plastic composite component (3). The invention also relates to a method for connecting a fiber-plastic composite component and a load introduction element and to the use of such a connection device.

Description

Technical Field

[0001] This invention relates to a connection device between a load-introducing element and a fiber-plastic composite component, wherein the load-introducing element is pressed into a cylindrical opening in the fiber-plastic composite component. The invention also relates to a method for connecting such a fiber-plastic composite component and an elongated load-introducing element, and the use of such a connection device. Background Technology

[0002] Fiber-plastic composite (FKV) components offer the advantage of high stability with minimal material usage, making them commonly used in lightweight construction. Lightweight construction is a key technology for efficient material and energy use. The aim of lightweight construction is to achieve structures with low mass, thereby optimizing the performance of machines and equipment. Clever structural design enables high stability with minimal material consumption.

[0003] Materials incorporating reinforcing fibers into a plastic matrix are called fiber-plastic composites. In fiber-plastic composite components, the use of these reinforcing fibers induces orientation-dependent elastic properties in the resulting material, thereby causing stiffness and strength related to fiber orientation. When using suitable initial materials, this reinforcement effect occurs in the direction parallel to the fibers.

[0004] In order to connect components made of fiber-plastic composites to other components, especially those made of metal, the special characteristics of the fiber-plastic composite components must be taken into account. Special attention needs to be paid to the connection points between load-introducing elements and structural elements made of fiber-plastic composites, where heavy loads are introduced into the structural elements, as is necessary, for example, when attaching torsion springs.

[0005] The load-introducing element is pressed into a fiber-plastic composite component, such as a fiber-plastic composite tube, for the purpose of transmitting torsion. Due to the pressing force, an increased axial strength of the fiber-plastic composite component is required. For this purpose, local reinforcement is introduced for axial reinforcement. In particular, additional unidirectional, especially tangentially oriented fiber layers and form-fitting connections are used. [1] During pressing, micro-toothed sections arranged at the load-introducing element are slotted in the unidirectional hose. Therefore, pressing poses a significant risk of damaging the torsion tube.

[0006] Furthermore, due to the unique properties of fiber-plastic composite components, the unidirectional hose results in a reduction in torsional stiffness under torsional stress. This reduced torsional stiffness is a significant drawback, especially in the case of torsion springs. In the field of lightweight construction, the additional material costs incurred by the introduction of the unidirectional hose are also undesirable. Summary of the Invention

[0007] The purpose of this invention is to achieve a connection between a load-introducing element and a component made of a fiber-plastic composite, which not only achieves torsional rigidity of the structural element but also avoids the other disadvantages listed, and in particular achieves the potential for lightweight construction of the component.

[0008] According to the present invention, the objective is achieved by a connecting device and a method. Advantageous embodiments of the invention are described herein.

[0009] The objective is achieved in particular by a connecting device comprising: an elongated load-introducing element having a truncated conical sub-region and a fiber-plastic composite component. The fiber-plastic composite component has a cylindrical opening into which the load-introducing element is pressed in the pressing direction.

[0010] Here, in the opening, at least three trapezoidal prism-shaped base elements, each having a base and two equal bottom surfaces, are arranged at intervals along the circular intersection line of the inner surface between the inner surface of the opening of the fiber-plastic composite component and the truncated conical sub-region of the load-introducing element, such that one bottom surface of the base element points in the pressing direction, and the base of the base element abuts against the inner surface of the prism-shaped opening. Furthermore, wedge-shaped trapezoidal prism-shaped pressure elements are arranged between two base elements. Here, the pressure element has a pressure base and two trapezoidal bottom surfaces of different sizes, wherein the thickness of the pressure element increases from one trapezoidal bottom surface to the other. The wedge-shaped trapezoidal prism-shaped pressure element is arranged between two base elements such that the pressure base, configured to correspond to the truncated conical sub-region of the load-introducing element, points towards the load-introducing element, and the thickness of the pressure element formed by the surface perpendicular to the pressure base increases in the pressing direction. In the sense of the present invention, the pressure element having a thickness that increases in one direction is wedge-shaped.

[0011] Here, a reversible surface pressure is formed between the base element and the pressure element, and between the truncated conical sub-region and the pressure base, wherein the deeper the load-introducing element is pushed into the fiber-plastic composite component, the stronger the surface pressure becomes.

[0012] In the context of this invention, a pressure base constructed in a manner corresponding to the truncated conical sub-region of the load-introducing element is a pressure base with the following shape: the shape matches the shape of the truncated conical sub-region of the load-introducing element, such that not only point contact is made between the pressure element and the load-introducing element, but surface pressure is also generated according to this invention.

[0013] Preferably, the intensity of the surface pressure is matched to the torque to be transmitted by means of the connecting device. Here, the permissible surface pressure of the fiber-plastic composite component in the radial direction must not be exceeded.

[0014] If the base element has contact with the inner surface of the opening of the fiber-plastic composite member at multiple points and the base points inward, then the base of the base element rests against the inner surface of the cylindrical opening. However, it is permissible for the base of the base element to only directly contact the inner surface in the edge regions. Reasons for this include, for example, the curvature of the cylindrical opening and possible recesses in the base of the base element. Preferably, the base, also referred to as the basal surface, comprises a supporting edge of a trapezoidal prism at the inner cladding surface of the cylindrical opening. For the base to rest against the inner surface in the sense of the invention, it is not necessary but permissible that the shape of the base be configured in a manner corresponding to the inner surface.

[0015] A trapezoidal prism is a prism having two opposing trapezoidal bases. Here, the base of the trapezoidal prism is as follows: the base comprises the two larger side portions of the two trapezoidal bases, i.e., the two larger side portions of the two parallel side portions of the two bases. The base of the trapezoidal prism is typically the face with the largest area of ​​the trapezoidal prism. Therefore, the pressure base is the face of the pressure element comprising the two longer side portions of the parallel side portions of the trapezoidal bases. In the case of a pressure element whose pressure base has a curved shape to match the shape of the truncated conical sub-region of the load-introducing element, the base has a shape that does not precisely correspond to the shape of a trapezoid, because one or both of the two truly parallel side portions are curved. In the sense of the invention, if one or both of the parallel side portions, i.e., the side portions extending at the same distance, are curved, then such a base also has a trapezoidal shape.

[0016] The trapezoidal prism is preferably configured as a straight trapezoidal prism. Importantly for this invention, the sides of the base element constituting the trapezoidal prism form obtuse angles with the base. Therefore, the sides are inclined compared to a cuboid. The base of the trapezoidal prism, i.e., the surface abutting the inner cladding of the prism opening, and other limiting interfaces of the trapezoidal prism are not necessarily flat surfaces, but may also have grooves or other recesses. In a feasible variation, the base has a curved shape corresponding to the arch of the prism opening.

[0017] The base surface of the base element is oriented outward toward the inner surface of the opening, while the pressure element is arranged such that the base surface of the pressure element is away from the inner surface and toward the load-introducing element.

[0018] In the context of this invention, the frustoconical sub-region is a region of the load-introducing element having a diameter that tapers in the pressing direction. In a preferred variant, the frustoconical sub-region is configured as an end region, i.e., arranged at the end of the load-introducing element, such that the diameter of the frustoconical sub-region tapers towards the end of the load-introducing element. Here, in one variant, the outer surface of the frustoconical sub-region of the load-introducing element is configured according to the type of the covering surface of the frustocone, and the cross-section or section of the frustoconical sub-region is circular. Here, each pressure base of the pressure element has a corresponding arched shape. Another variant proposes that the cross-section or section of the frustoconical region corresponds to n angles. Here, the number of angles n corresponds to the number of pressure elements. Thus, the pressure base of the pressure element is not configured in a curved or arched manner, but rather flat, possibly with a recess.

[0019] In the context of this invention, a structural element is elongated if it is significantly larger in the first dimension than in the other two dimensions. Preferably, the element is at least five times larger in the long dimension than in the other two dimensions, and particularly preferably at least ten times larger.

[0020] The inner surface of the opening corresponds to the covering surface of the cylindrical opening, that is, the covering surface of the geometry of the cylinder.

[0021] The pressure element is configured as a wedge-shaped element with a trapezoidal base, wherein the side facing the load-introducing element, i.e., the pressure base, matches the shape of the load-introducing element. In a feasible variation, the pressure base has a recess. Here, only the area surrounding the recess is configured in a manner corresponding to the shape of the load-introducing element. The surface of the recess is preferably less than 50% of the surface of the pressure base, particularly preferably less than 20% of the surface of the pressure base. In a feasible variation, a slotted wedge or slider serves as both the base element and the pressure element.

[0022] According to an advantageous design, the fiber-plastic composite component is configured as a tube or hollow shaft, optionally as a torsion spring or torsion shaft. The fibers of the fiber-plastic composite component are optionally diagonally, i.e., obliquely, oriented relative to the pressing direction in the region of the connecting device. Here, according to a suitable embodiment, the fibers of the fiber-plastic composite component form an angle of 30° to 60°, preferably 45°, with respect to the pressing direction. An alternative embodiment proposes that the fiber orientation is 90°, thereby producing the highest possible radial strength. A preferred embodiment has three inner layers at 0°, and above said inner layers a plurality of, for example, 22 layers with an orientation of 45°.

[0023] In a feasible variation, the load-introducing element is made of metal.

[0024] The connecting device according to the invention eliminates the need for an additional unidirectional layer. This ensures higher torsional stiffness of the fiber-plastic composite component on the one hand, and the connection offers improved potential for lightweight construction on the other. The connecting device according to the invention can advantageously be configured as a detachable connection. Damage to the fiber-plastic composite component caused by compression from a load-introducing element with micro-toothed sections is eliminated.

[0025] Another aspect of the present invention relates to a method for connecting a fiber-plastic composite component having a cylindrical opening and an elongated load having a truncated conical sub-region to an element, the method comprising the steps of:

[0026] a) At least three base elements having the shape of straight trapezoidal prisms are arranged inside the opening, each base element having two congruent trapezoidal bases and a base. Here, the base elements are arranged at equal intervals from each other along the circular intersection of the opening, such that the base points toward the inside of the opening, i.e., toward the fiber-plastic composite component, and the normals of the trapezoidal bases extend parallel to the central axis of the opening.

[0027] (b) A number of wedge-shaped trapezoidal prism-shaped pressure elements, the same number as the base elements, are held between the base elements. Each pressure element has two trapezoidal bases of different sizes and a pressure base, wherein the thickness of the pressure element increases from one trapezoidal base to the other. One pressure element is positioned between each of the two base elements. The pressure elements are arranged such that the pressure base of the pressure element points towards the central axis, the normal of the trapezoidal base extends parallel to the central axis, and the thickness of the pressure element perpendicular to the pressure base increases in the pressing direction towards the opening. Here, the pressure base is configured to correspond to the shape of the truncated conical sub-region of the load-introducing element, i.e., the outer surface.

[0028] c) The load-introducing element is pressed between the pressure elements, creating surface pressure between the truncated cone sub-region and the pressure base of the pressure element. The deeper the load-introducing element is pushed into the fiber-plastic composite member, the stronger the surface pressure. Here, the load-introducing element is pressed approximately to the center of the arranged pressure elements.

[0029] The pressure element is preferably held in a cage-like frame.

[0030] Another aspect of the invention relates to the use of a connecting device according to the invention in a bogie of a rail vehicle, i.e., in a torsion spring bogie frame.

[0031] According to the concept, the axial pressing of the truncated conical sub-region of the load-introducing element radially outward compresses the corresponding pressure element. By increasing the thickness of the pressure element, a compressive force is constructed on the fiber-plastic composite component, and a force-fitted connection is established. Thus, a pressure connection is created for introducing a load into the fiber-plastic composite component. This connection can also be disengaged by disconnecting the load-introducing element.

[0032] In order to achieve the present invention, the above-described design schemes and embodiments according to the present invention are also combined with each other in an arrangement that is in accordance with the purpose. Attached Figure Description

[0033] The invention is described in more detail below with reference to embodiments. The embodiments relate to connection devices according to the invention, and the invention is described herein without limiting it.

[0034] The invention will be described in more detail with reference to the accompanying drawings. Herein lies:

[0035] Figure 1 The connecting device is shown in a perspective view.

[0036] Figure 2A The basic element is shown in the shape of a trapezoidal prism.

[0037] Figure 2B The pressure element is shown in a wedge-shaped trapezoidal prism form.

[0038] Figure 3 The connecting device is shown in an exploded view.

[0039] Figure 4 A cross-sectional view of the connecting device is shown, and

[0040] Figure 5 Showing according to Figure 4 A partial cross-sectional view. Detailed Implementation

[0041] Figure 1 A feasible embodiment of the connecting device 1 is shown in three-dimensional form. Here, the components of the connecting device 1 are shown side-by-side, i.e., shown as an exploded view. The connecting device 1 is used for the connection between the load-introducing element 2 and the fiber-plastic composite component 3. In the cylindrical opening 4 of the fiber-plastic composite component 3, base elements 5 are arranged at intervals within the cylindrical opening 4. The base elements 5 can be held in position, for example, by means of a mesh or cage. A pressure element 6 is positioned in the intermediate space between the base elements 5. The thickness of the pressure element 6 increases in the pressing direction 7, such that the base elements 5 and the fiber-plastic composite component 3 can be combined to ensure a pressure connection between the load-introducing element 2 and the pressure element 6.

[0042] Basic component 5 has in Figure 2A The shape of the trapezoidal prism is schematically shown. Preferably, the base element 5 has the shape of a straight trapezoidal prism. The two opposing bases 8.1 of the base element 5 are congruently formed, and therefore have the same dimensions and a trapezoidal shape. The two longer sides of the parallel sides are also the sides of the base 9 of the base element 5, which points downwards here. In the sense of the invention, the thickness 10.1 of the base element 5 is the shortest connection between the two parallel sides of the base 8.1. The side faces 11 of the trapezoidal prism are inclined relative to the side faces of the cuboid.

[0043] exist Figure 2B The pressure element is schematically shown. The pressure element 6 is, in principle, a wedge-shaped or wedge-shaped trapezoidal prism, wherein the thickness 10.2 of the pressure element 6 increases from one trapezoidal base 8.2 to another trapezoidal base 8.3. The two trapezoidal bases 8.2, 8.3 are connected via a side surface 11.2 and a downward-pointing pressure base 15 as shown in the diagram. Here, the pressure base 15 is constructed to be larger than its opposing upper side 16. In this embodiment, both the pressure base 15 and the upper side 16 have curved shapes to match the shape of the truncated conical sub-region of the load-introducing element (not shown).

[0044] Figure 3 An exploded view of the connecting device 1 for connecting the load introduction element 2 and the fiber-plastic composite component 3 is shown. In the cylindrical opening 4 of the fiber-plastic composite component 3, the base element 5 is arranged at the inner surface 12 of the opening 4. The base element 5 is positioned circularly along the intersection line 13 of the inner surface 12. The intersection line 13 shown here extends along the inner surface of the cylindrical opening 4, wherein the intersection line extends perpendicular to the pressing direction 7. Thus, a circular intersection line 13 is obtained. The base 9 abuts against the inner surface 12 of the cylindrical opening 4. The base surface of the pressure element 6 points inward. The thickness of the pressure element 6 increases in the pressing direction 7. The load introduction element 2 has a truncated conical sub-region 14 in its end region. In this embodiment, the truncated conical sub-region 14 has only a very small variation in its outer diameter, wherein the outer diameter tapers in the pressing direction 7.

[0045] Figure 4 A cross-sectional view of the connecting device 1 is shown, wherein in Figure 5The image shows an enlarged view of region A. The load-introducing element 2 is at least partially arranged within the fiber-plastic composite member 3. Multiple base elements 5 are arranged at intervals between the load-introducing element 2 and the fiber-plastic composite member 3. Pressure elements 6 are arranged in the region between the base elements 5. The base elements 5 are arranged such that their bases 9 abut against the inner surface 12 of the fiber-plastic composite member 3, i.e., pointing outwards. The bases 15 of the pressure elements 6 point inwards and abut against the load-introducing element 2. Surface pressure exists between the load-introducing element 2 and the bases 15 of the pressure elements 6. The shape and arrangement of the pressure elements 6 and the base elements 5 convert the axial force generated by pressing into the load-introducing element 2 into a radial force.

[0046] Cited non-patent literature:

[0047] [1] "Konstruktion und technologische Umsetzung von hochbeanspruchtenLasteinleitungssystemen für neuartige Leichtbaustrukturen in Faserverbundbauweise", Dissertation von Dipl.Ing. Olaf Helms, TU Dresden, 2006

[0048] List of reference numerals

[0049] 1. Connecting device

[0050] 2 Load-introducing components

[0051] 3. Fiber-plastic composite components, components made of fiber-plastic composites

[0052] 4 openings

[0053] 5 basic components

[0054] 6. Pressure elements, wedge-shaped pressure elements, wedge-shaped pressure elements

[0055] 7 Pressing direction

[0056] 8.1 Bottom surface of basic components

[0057] 8.2 The bottom surface of the pressure element, and the smaller bottom surface of the pressure element

[0058] 8.3 The bottom surface of the pressure element, and the larger bottom surface of the pressure element

[0059] 9. Base of basic components

[0060] 10.1mm thickness

[0061] 10.2 Thickness of pressure element

[0062] 11.1 Side View

[0063] 11.2 Side of the pressure element

[0064] 12 inner surfaces, inner surfaces of openings

[0065] 13 intersection lines

[0066] 14. Frustum-shaped sub-region, sub-region, and end region

[0067] 15. Pressure base, pressure element base

[0068] 16. Upper side of pressure element

[0069] Partial view of section A

Claims

1. A connection device (1) having an elongated load introduction element (2) with a truncated conical subregion (14) and a fiber-plastic composite component (3) with a cylindrical opening (4), the load introduction element (2) being pressed into the opening in a pressing direction (7), wherein in the opening (4), between the inner face (12) of the opening (4) and the truncated conical subregion (14) of the load introduction element (2), along a circular intersection line (13) of the inner face (12), at least three trapezoidal prismatic base elements (5) with one base (9) and two congruent base faces (8.1) are arranged in a spaced-apart manner, so that one of the base faces (8.1) of the base elements (5) is directed in the pressing direction (7) and the base (9) of the base elements (5) rests against the inner face (12), wherein between two base elements (5) respectively a wedge-shaped trapezoidal prismatic pressure element (6) with two differently sized trapezoidal base faces (8.2, 8.3) and one pressure base (15) is arranged, the thickness (10.2) of the pressure element increasing from one trapezoidal base face (8.2) to the other trapezoidal base face (8.3), so that the pressure base (15) constructed in correspondence with the truncated conical subregion (14) of the load introduction element (2) is directed toward the load introduction element (2) and the thickness (10.2) constructed perpendicular to the pressure base (15) increases in the pressing direction (7), wherein a reversible surface pressure is constructed between the base elements (5) and the pressure elements (6) and between the truncated conical subregion (14) and the pressure base (15), the strength of the surface pressure increasing the deeper the load introduction element (2) is pushed into the fiber-plastic composite component (3).

2. The connection device (1) according to claim 1, characterized in that The fiber-plastic composite component (3) is a torsional spring.

3. The connection device (1) according to claim 1 or 2, characterized in that The fibers of the fiber-plastic composite component (3) are oriented diagonally with respect to the pressing direction (7) in the region of the connection device (1).

4. The connection device (1) according to claim 1 or 2, characterized in that The load introduction element is composed of metal.

5. The connection device (1) according to claim 1 or 2, characterized in that The pressure base (15) has a recess.

6. The connection device (1) according to claim 1 or 2, characterized in that The truncated conical subregion (14) has a circular cross section and the pressure base (15) has an arch-shaped shape corresponding to the circular cross section.

7. The connection device (1) according to claim 1 or 2, characterized in that The cross section of the truncated conical subregion (14) has the shape of n corners and the number of pressure elements (6) corresponds to the number of corners.

8. A method for connecting a fiber-plastic composite component (3) with a cylindrical opening (4) and an elongated load introduction element (2) with a truncated conical subregion (14), the method comprising the following steps: a) arranging at least three base elements (5) having the shape of straight trapezoidal prisms with two congruent trapezoidal bases (8.1) and a base (9) inside the opening (4), wherein the base elements (5) are arranged uniformly spaced apart from one another along a circular intersection (13) of the opening (4) such that the base (9) is directed to the inner face (12) of the opening (4) and the normals of the trapezoidal bases (8.1) extend parallel to the central axis of the opening (4), b) holding a number of pressure elements (6) having the shape of trapezoidal prisms with wedge-shaped trapezoidal bases (8.2, 8.3) and a pressure base (15) between the base elements (5) in the same number as the base elements (5), wherein the thickness (10.2) of the pressure elements (6) increases from one trapezoidal base (8.2) to the other trapezoidal base (8.3) such that the pressure base (15) of the pressure elements (6) is directed to the central axis and the normals of the trapezoidal bases (8.2, 8.3) extend parallel to the central axis and the thickness (10.2) of the pressure elements (6) perpendicular to the pressure base (15) increases in the direction of penetration (7) of the opening (4), wherein the pressure base (15) is formed in a manner corresponding to the shape of the truncated conical subregion (14) of the load introduction element (2), c) pressing the load introduction element (2) between the pressure elements (6) such that a surface pressure arises between the truncated conical subregion (14) and the pressure base (15) of the pressure elements (6), the intensity of the surface pressure increasing the deeper the load introduction element (2) is pushed into the fiber-plastic composite component (3).

9. The method of claim 8, wherein, The pressure elements (6) are held in a cage-like frame.

10. Use of the connection device (1) according to any one of claims 1 to 7 in a bogie of a rail vehicle.

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