METHOD FOR MANUFACTURING A RIVET CONNECTION OF A FIBER COMPOSITE COMPONENT

Abstract

A method for manufacturing a rivet connection of a fiber composite component. The method includes positioning a first component which contains a fiber composite material in an overlap joint with a second component, laser-drilling a shared through-hole at least through the fiber composite material of the first component, inserting a rivet into the through-hole and fixing the rivet to the first and to the second component.

Claims

1. A method for manufacturing a rivet connection of a fiber composite component, comprising: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

2. The method of claim 1, wherein the laser-drilling is carried out using a high-energy laser beam.

3. The method of claim 2, wherein the high-energy laser beam has a laser power in the kilowatt range.

4. The method of claim 1, wherein the second component likewise contains a fiber composite material which is drilled through during the laser-drilling.

5. The method of claim 1, wherein the fiber composite material contains carbon fibers, some of which are partially drilled through by the laser-drilling.

6. The method of claim 1, wherein a laser beam is widened or defocused for laser-drilling in a manner adapted to a desired hole diameter.

7. The method of claim 6, wherein the laser beam is initially more heavily widened or defocussed, and subsequently less and less so down to the desired hole diameter, to form a conical entry to the through-hole which is formed for countersinking a rivet head.

8. The method of claim 1, wherein at least the first component is provided in planar form.

9. The method of claim 8, wherein a plurality of parallel joint lines are provided along an edge of the first component.

10. The method of claim 1, wherein a multiplicity of shared through-holes of the first component and second component are formed in a line extending along an edge of the first component by laser-drilling, a rivet being inserted into each of the through-holes and fixed to the first and the second component to form an in particular uniformly continuous joint line.

11. The method of claim 10, wherein a plurality of parallel joint lines are provided along an edge of the first component.

12. A structural arrangement, comprising: a first component which contains a fiber composite material and a second component, the first and the second component being connected using a rivet connection manufactured by a method comprising: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

13. The structural arrangement of claim 12, wherein a through-hole of the rivet connection comprises a hole wall which comprises a surface which is manufactured without cutting.

14. The structural arrangement of claim 13, wherein the surface of the hole wall is covered with material directly solidified from the molten liquid state.

15. The structural arrangement of claim 13, wherein the surface of the hole wall is manufactured by direct evaporation.

16. A method for manufacturing a vehicle skin, the method comprising: providing a first component in a form of a first skin portion which contains a fiber composite material; providing a second component, in particular in a form of a second skin portion or a connecting portion for connecting the first skin portion to a second skin portion in a butt joint; and connecting the first component to the second component using a rivet connection manufactured by a method comprising: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

17. A vehicle skin manufactured by a method comprising: providing a first component in a form of a first skin portion which contains a fiber composite material; providing a second component, in particular in a form of a second skin portion or a connecting portion for connecting the first skin portion to a second skin portion in a butt joint; and connecting the first component to the second component using a rivet connection manufactured by a method comprising: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

18. A use of a laser-drilling process to manufacture a rivet connection of a fiber composite component by a method comprising: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

19. The use according to claim 18, wherein the laser-drilling process for manufacturing a rivet connection of a vehicle skin by a method comprises: positioning a first component which contains a fiber composite material in an overlap joint with a second component; laser-drilling a shared through-hole at least through the fiber composite material of the first component; inserting a rivet into the through-hole; and fixing the rivet to the first and to the second component.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In the following, the disclosure herein is described in greater detail by way of embodiments with reference to the accompanying example drawings.

[0053] In the drawings:

[0054] FIG. 1 is a perspective view of an example of manufacturing through-holes for rivet connections;

[0055] FIG. 2A-2C are cross-sectional drawings of the typical steps for manufacturing a rivet connection for connecting two skin portions;

[0056] FIG. 3A shows an arrangement for laser-drilling a fiber composite component;

[0057] FIG. 3B is a cross-sectional view of a fiber composite material component drilled through by laser-drilling;

[0058] FIG. 4A shows an arrangement for drilling through two fiber composite material components in an overlap joint;

[0059] FIG. 4B is a cross-sectional view of a structural arrangement comprising a rivet connection of two fiber composite material components;

[0060] FIG. 5 is a perspective drawing of a fuselage portion of an aircraft or spacecraft; and

[0061] FIG. 6 is a perspective drawing of two fiber composite material components connected in a butt joint by a connecting portion.

[0062] In the drawings, unless stated otherwise, like reference numerals denoted like or functionally equivalent components. The drawings are not necessarily to scale with one another.

DETAILED DESCRIPTION

[0063] FIG. 1 is a perspective view of an example of manufacturing through-holes 103 for rivet connections.

[0064] The components to be connected are two skin portions 101 and 102 of a fiber composite material airplane fuselage. To manufacture the through-holes 103, a drilling template 106 is manually positioned and fixed, for example by an adhesive strip 107 as shown. Subsequently, a through-hole 103 is drilled in the skin portions 101, 102 using a hand-operated power drill 105.

[0065] FIG. 2A-2C are cross-sectional drawings of the typical steps for manufacturing a rivet connection for connecting two skin portions 101, 102.

[0066] In a first step in accordance with FIG. 2A, through-holes 103 are drilled in an overlap region of the fiber composite material skin portions 101, 102 in the manner described in FIG. 1, by mechanical cutting using a hand-operated power drill at a position specified using a drilling template 106.

[0067] In a second step in accordance with FIG. 2B, the through-holes 103 are cleaned of drilling dust and residues. This takes place for example by pressurised air from both sides, as is indicated schematically using flow lines and directional arrows. This cleaning step is important when fiber composite materials are machined using a conventional drill, since very fine carbon dust occurs when the material is cut and easily accumulates in the hole 103.

[0068] In a third step in accordance with FIG. 2C, rivets 104 are introduced into the through-holes 103 by a riveting tool (not shown) and fixed to the two skin portions 101, 102 by deforming the rivet.

[0069] FIG. 3A shows an arrangement for laser drilling a fiber composite component.

[0070] By way of example, a first component 1 made of carbon-fiber-reinforced plastics material is provided as the fiber composite component.

[0071] The arrangement comprises laser optics 8, which are carried and positioned by a robot 7. The robot 7 may for example be a conventional industrial robot having a suitable mounting.

[0072] The laser optics 8 are supplied with laser radiation from a laser source 9 via an optical fiber 15. For example, the laser source 9 is a high-energy solid-state laser, in particular a disc laser or fiber laser, having a laser power in the kilowatt range.

[0073] Preferably, a laser beam 5 generated thereby has a high brilliance. The brilliance B is defined as the quotient of the laser power P.sub.L divided by the product of the beam quality factor M.sup.2 and the wavelength λ of the laser beam. The beam quality factor M.sup.2 denotes the degree of divergence of the beam path. It is known in principle to a person skilled in the art how to derive the beam quality factor for transverse electromagnetic modes (TEM.sub.mn), and so a theoretical explanation is omitted herein. The brilliance which can be calculated in this manner is a measure of the quality of the laser beam. In practice, the beam parameter product (BPP), based on the beam quality factor M.sup.2 in terms of calculation, is often given in connection with the laser power P.sub.L so as to express the beam quality.

[0074] The laser optics are positioned above a first fiber composite material component 1 to be drilled through by a robot 7 in such a way that the focal position of the laser beam 5 is at the level of the first component 1. In the theoretical ideal case, the laser beam can be focussed to a minimum diameter corresponding to the fiber diameter of the optical fiber 15.

[0075] To drill through the first component 1, a multiplicity of laser pulses are emitted onto the first component, for example by percussion drilling, in such a way that the material of the first component 1 evaporates, the laser beam 5 digs further into the first component 1, and material vapor 10 escapes from the resulting hole. This is repeated until a through-hole is manufactured.

[0076] The laser beam 5 evaporates both the matrix material and the fiber material of the fiber composite material equally. In particular, in the case of carbon-fiber-reinforced plastics materials, the laser beam evaporates both the plastics material matrix and the carbon fibers in the region of the through-hole.

[0077] Because of the different thermophysical properties of the fibers and the matrix material, particular constraints should be adhered to when laser-drilling fiber composite materials. In particular in carbon-fiber-reinforced plastics materials, care should be taken that the temperatures within the component do not exceed material-dependent thresholds in the environment of the through-hole to be manufactured as a result of thermal conduction along the carbon fibers. Thresholds of this type may for example be the glass transition temperature and the evaporation temperature, and in the case of thermoplastic systems the melting point of the matrix.

[0078] It is therefore advantageous to aim for a high degree of sublimation or ablation. The intensity of the laser beam is selected to be appropriately high so as to be able to evaporate both the matrix material and the fibers of the fiber composite material.

[0079] So as to achieve a desired diameter of the through-hole, for example a through-hole manufactured by percussive drilling can be widened by trepanning, in other words moving the component or the laser optics in a circle around the centre of the through-hole.

[0080] Alternatively or additionally, a spiral drilling process may be used or carried out to drill through the first component 1. In this process, depending on the type of construction, the laser beam (for example using movable mirror optics, known as a scanner) or the laser beam optics (by moving the robot accordingly) or the first component (by moving a mounting accordingly) constantly rotates around the centre of the through-hole to be manufactured, in such a way that a hole having the desired diameter is produced directly. Superposed movements are also conceivable, in particular in the case of a scanner provided as laser optics and mounted on the robot.

[0081] An alternative to laser-drilling involves directing a high-energy laser beam having sufficiently high laser power, for example a CO.sub.2 laser, a fiber laser or a disc laser, for example having a power >3 kW, in particular >6 kW, onto the first component 1 in a configuration in which a beam diameter directly corresponds to the desired diameter of the through-hole. This is the case in FIG. 3A, and can be achieved by way of appropriately configured laser optics 8 having an appropriate imaging ratio, by optically defocussing the laser beam 5, by adjusting a relevant distance from the focal position and/or by way of an appropriately thick diameter of an optical fiber from the laser source to the laser optics. Because of the high power, the intensity of the laser beam 5 is still high enough to evaporate the material both of the matrix and of the fibers of the fiber composite material.

[0082] In this way, by single-pulse or percussive drilling, by which the laser beam works into the fiber composite material, a through-hole can be produced directly at the desired diameter.

[0083] Naturally, these drilling process are merely examples of a possible implementation. Further drilling strategies or drilling processes are also possible.

[0084] In particular, a continuous laser may be used as a laser source. However, a pulsed laser would also be conceivable.

[0085] FIG. 3B is a cross-sectional view of a fiber composite material component drilled through by laser-drilling.

[0086] This first component 1 accordingly comprises a through-hole 3. The hole wall 11, manufactured by laser-drilling, of the through-hole 3 is a completely smooth and clean surface without residues of the drilling dust. It is in particular a surface which is covered with material directly solidified from the molten liquid state or which is manufactured by direct evaporation.

[0087] The material melted on by the laser beam 5 has for example been left behind on the hole wall 11 when the melt was driven out or been melted on during the laser-drilling.

[0088] FIG. 4A shows an arrangement for drilling through two fiber composite material components 1, 2 in an overlap joint.

[0089] The two components 1, 2 arranged in an overlap joint consist of or comprise for example carbon-fiber reinforced plastics material and are occupied by a drilling template 6, for positioning or orientating the laser optics 8, on a face provided for the entry of the laser beam 5.

[0090] As explained in relation to FIG. 3A, the laser optics 8 are mounted on a robot 7. The associated laser source 9 and the optical fiber 15, which supply the laser optics, are not shown here for improved clarity.

[0091] The embodiment shown is in particular a semi-automatic system. In other words, the laser optics 8 are oriented onto recesses provided in the drilling template 6, in a robot-assisted manner but under the control of a user. For this purpose, the laser source 9 comprises a search laser which emits a visible light beam through the fiber in such a way that a light point is projected onto the targeted point by the laser optics.

[0092] Alternatively, the drilling template 6 may also be fixed in position and be formed as a positioning means or stop for the first and second components 1, 2. In this case, the approach towards the positions for drilling may be programmed or saved (for example by learning or teaching) into a control system of the robot 7.

[0093] Further, a laser machining pattern or a machining sequence may be programmed into a control system of the laser source 9 and/or of the laser optics 8.

[0094] After the components 1, 2 and/or the drilling template 6 have been positioned, an automatic sequence of the drilling process can be initiated.

[0095] As a further alternative, in the case of specified and/or automatic positioning of the components 1, 2 an automatic sequence of the drilling process could also be initiated without a template.

[0096] By way of example, in the embodiment shown three through-holes 3 uniformly spaced apart from one another are provided in each cross-sectional plane.

[0097] The through-holes 3 are formed by laser-drilling in the manner described in relation to the previous FIGS. 3A and B. To form conical entries to the through-holes for countersinking a rivet head, the laser beam is initially more heavily defocussed, and subsequently less and less so down to the desired hole diameter. The intensity of the laser beam always remains high enough to evaporate both the matrix material and the fibers of the fiber composite material.

[0098] Arrangements of this type for (semi-)automatically laser-drilling fiber composite components may be adapted to different desired hole diameters and to different component thicknesses. Thus, by comparison with a method according to FIG. 1 or 2A, much higher production speeds are possible, merely requiring a fraction of the time to manufacture the through-holes 3.

[0099] Further, arrangements of this type advantageously operate without any variation in the quality of the laser-drilled through-holes 3. By contrast, in mechanical drilling methods, as described in relation to FIGS. 1 and 2A, a drill loses sharpness and thus precision with continued use. This can be discerned in microscope images of the drilled holes by way of increased occurrence of drilling dust and unclean or rough surfaces.

[0100] FIG. 4B is a cross-sectional view of a structural arrangement 16 comprising a rivet connection 17 of two fiber composite material components 1, 2.

[0101] The two components 1, 2 arranged in an overlap joint and provided with through-holes 3 by laser-drilling are connected by rivets 4, which are introduced into the through-holes 3 and subsequently fixed to the first component 1 and to the second component 2.

[0102] In this connection, it should in particular be noted that no additional cleaning step is required before the rivets 4 are introduced, since when the through-holes 3 are laser-drilled no drilling dust, in particular no carbon dust, occurs.

[0103] The fixing takes place in the manner conventional to a person skilled in the art, in particular by way of a positive connection provided on the rivet 4 by way of a rivet head at the entry face and a positive and non-positive connection provided by shaping at the exit face.

[0104] FIG. 5 is a perspective view of a vehicle skin 20. In the embodiment shown, this is a vehicle skin 20 in the form of a fuselage portion of an aircraft or spacecraft.

[0105] The fuselage portion comprises a first skin portion 18 as the first component 1 and a second skin portion 19 as the second component 2. The two skin portions 18, 19 are arranged in an overlap joint with one another in the region of a rivet connection 17. A plurality of joint lines 13, typically three parallel joint lines, are provided parallel to an edge 14 of the first skin portion 18 by through-holes, each having an inserted and fixed rivet 4.

[0106] In total, the fuselage portion shown consists of or comprises by way of example four skin portions, which are each curved and which are arranged to form a tubular fuselage shape and interconnected in the same manner as the first skin portion 18 and the second skin portion 19.

[0107] FIG. 6 is a perspective view of two fiber composite material components 1, 12 connected in a butt joint by a connecting portion 2′.

[0108] This is a structural arrangement 16 comprising two components 1, 12 in a butt joint, which are connected via the connecting portion 2′ using a rivet connection 17.

[0109] For this purpose, the first component 1 and a further component 12 are arranged with respect to one another and covered with a connecting portion 2′ formed as a doubler in the region of the butt joint. The connecting portion 2′ is arranged overlapping with each of the components 1, 12 and in each case connected by at least one joint line 13 of through holes 3, for example a plurality as shown here, in particular three, each having an inserted and fixed rivet 4.

[0110] Thus, in this embodiment, the connecting portion 2′ formed as a doubler forms the second component arranged in an overlap joint with the first component 1 and connected by rivet connection.

[0111] In this case too, the joint lines 13 accordingly extend along an edge 14 of the first component 1.

[0112] Although the present disclosure has been described herein by way of several embodiments, it is not limited thereto, but can be modified in numerous ways.

[0113] For example, for different applications, a wide range of different types of rivets may be used, for example including hollow rivets, blind rivets, spread rivets or the like instead of solid rivets.

[0114] In one embodiment, it is conceivable to provide one of the components with pre-drilled holes, in such a way that the shared through-hole can only be produced through the fiber composite material of the other component by laser-drilling. Subsequently, the components can be riveted. In particular, holes of the pre-drilled component which are pre-drilled in this manner may be provided with countersinks for receiving a rivet head in a flush manner.

[0115] Instead of skin portions, the first and second components 1, 2 may be any type of structural component of a structural arrangement.

[0116] As an alternative to a fuselage for an aircraft or spacecraft, skin portions of other types of vehicle skins containing fiber composite components may be provided with a rivet connection 17 in the manner according to the disclosure herein, for example body parts of a motor vehicle or fuselage parts of a boat or ship.

[0117] While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a”, “an” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.