Method for connecting a fibre composite material to a metal surface, and fibre composite material-laying device

Abstract

The invention relates to a method for connecting a fibre composite material (14) to a metal surface (20) of a component (16), comprising the steps of: applying the fibre composite material (14), which has a planar textile (26) and a matrix (28) which is made of matrix material (29) and embeds the textile (26), onto the metal surface (20); and exerting a consolidation force (FK), directed towards the metal surface (20), onto the fibre composite material (14), wherein the metal surface (20) has a microstructure having a large number of micro recesses (24). The method also comprises the step of applying an oscillating shear force (Fs) onto the fibre composite material (14), such that matrix material (29) is introduced into the micro recesses (24).

Description

[0001] Method for bonding a fiber composite material to a metal surface and fiber composite material laying device

[0002] The invention relates to a method for bonding a fiber composite material to a metal surface of a component, comprising the steps of (a) applying the fiber composite material, which comprises a flat textile and a matrix of matrix material embedding the textile, to the metal surface, and (b) exerting a consolidation force on the fiber composite material directed toward the metal surface. According to a second aspect, the invention relates to a fiber composite material laying device.

[0003] Combining metal components with fiber-reinforced composites offers numerous advantages, as it combines the favorable properties of metal and fiber-reinforced composites. For example, fiber-reinforced composites combine the tensile strength of fiber-reinforced composites with the toughness of metallic materials.

[0004] However, it has proven problematic to join fiber composite materials with a metal component.

[0005] Applying fiber composites to metal surfaces is a known practice. This has the disadvantage of creating three interfaces: from the metal surface to the adhesive, and from the adhesive to the fiber composite. Such interfaces can be defective, thus reducing the strength of the bond. Furthermore, non-destructive testing of the interfaces is difficult.

[0006] DE 10 2012 017 593 A1 discloses a laying head for the automated placement of blanks of a flat material onto a laying surface. The head comprises a storage device for rotatably supporting a supply roll with wound composite material, a conveying and laying device, and a draping system for draping supplied composite material onto the laying surface and for removing the carrier material from the draped composite material. The draping system has a series of draping rollers arranged side by side for pressing the composite material onto the laying surface. The pressure force and / or pivoting angle of each draping roller can be individually adjusted.

[0007] DE 102000 1503 307 A1 describes a composite material consisting of a metal layer, an intermediate layer, and a fiber-reinforced plastic matrix. To improve the adhesion between the plastic matrix and the metal layer, the intermediate layer engages undercuts formed in the metal layer.

[0008] US 2022 / 0176489 A describes an apparatus for manufacturing a metal-composite patch part, comprising a laser oscillator that oscillates a laser; a first laser irradiator used to perform pattern processing on a surface of a metal with a laser by receiving the laser from the laser oscillator; and a metal-composite bonding device for bonding a composite tape to one surface of the pattern-processed metal. The apparatus includes a feed roller that feeds a composite tape onto one surface of the pattern-processed metal and a pressure roller that presses the composite tape onto one surface of the metal. The bonding performance between the metal and the composite material and productivity can be improved because the number of processes involved in the manufacturing process of the metal-composite patch part can be significantly reduced.

[0009] The invention is based on the object of improving the bonding of fiber composite materials with a metal surface.

[0010] The invention solves the problem by a generic method in which the metal surface has a microstructure with a plurality of micro-recesses, wherein the method comprises the step of applying an oscillating shear force to the fiber composite material such that matrix material is introduced into the micro-recesses. According to a second aspect, the invention solves the problem by a fiber composite material laying device for bonding a fiber composite material to a metal surface, comprising (a) an application head for applying the fiber composite material to the metal surface and (b) a consolidation roller for exerting a consolidation force directed toward the metal surface on the fiber composite material, wherein (c) the consolidation roller is designed to apply an oscillating shear force to the fiber composite material.

[0011] The advantage of the invention is that an adhesive for bonding the fiber composite material to the metal surface is dispensed with. This reduces the number of interfaces to one, namely the transition from the metal surface to the fiber composite material.

[0012] Another advantage is that, compared to state-of-the-art processes, a stronger bond between the fiber composite material and the metal surface can generally be achieved.

[0013] Another advantage is that the increased strength of the connection between the fiber composite material and the metal surface can be achieved using comparatively simple equipment.

[0014] In the context of this description, the application of the fiber composite material is understood in particular to mean automatic application. The application of the fiber composite material is understood in particular to mean bringing it into contact. Preferably, the application is a laying-on or rolling-on process.

[0015] The characteristic that the textile is flat means, in particular, that it is not merely a single thread. Furthermore, the flat textile is significantly larger in two spatial directions than in the remaining third spatial dimension, namely the thickness dimension.

[0016] The feature of applying an oscillating shear force is understood, in particular, to mean that a periodically oscillating shear force is applied. In particular, the oscillating shear force is applied for the purpose of introducing the matrix material into the micro-recesses. In other words, the shear force is not a byproduct of another process step, such as draping.

[0017] According to one embodiment, the oscillating shear force is applied such that the shear force has the same force direction at all points where it is applied to the fiber composite material, preferably always, at least 50% of the time, in particular at least 60% of the time, in particular at least 70% of the time, in particular at least 80% of the time, in particular at least 90% of the time. Preferably, the force vectors of the shear force always run in the same direction at the points where the shear force is applied.

[0018] According to one embodiment, the oscillating shear force is applied continuously. This particularly means that the oscillating shear force is applied such that the surface processed under the applied oscillating shear force, at which the fiber composite material is bonded to the metal surface, amounts to at least 40%, in particular at least 50%, in particular at least 60%, preferably at least 70%, preferably at least 80%, particularly preferably at least 90%, of the surface at which the metal surface is bonded to the fiber composite material.

[0019] The fiber composite material is preferably applied to the metal surface by a movement along the metal surface. This movement can be carried out, for example, by a robot. For example, the fiber composite material is applied using the application head. The invention also particularly relates to a robot that has a fiber composite material laying device. This is preferably attached to an arm of the robot. The robot is preferably designed to guide the fiber composite materials, the laying device, in particular its application head, along the metal surface. The robot preferably has at least two, in particular at least three, preferably at least four, axes.

[0020] The exertion of the consolidation force directed toward the metal surface is understood in particular to mean that a force is applied to the fiber composite material that is greater in the normal direction to the metal surface in the area of ​​the lay-up front than in the tangential direction. The lay-up front is the area where the fiber composite material comes into contact with the metal surface to bond it. In the present method, the lay-up front is also, in particular, the area in which a material-to-material and / or form-fitting connection is formed between the fiber composite material and the metal surface or the component with the metal surface.

[0021] The shear force is preferably applied in the longitudinal and / or transverse direction of the fiber composite material. In other words, the shear force is not applied in the thickness direction. In particular, the shear force is applied to the fiber composite material at the lay-up front.

[0022] It is advantageous if the consolidation force has a force component in the normal direction which is at least 75 Newtons, in particular at least 100 Newtons and / or at most 800 Newtons, in particular at most 56 Newtons, for example at most 500 Newtons.

[0023] The oscillation frequency of the oscillating shear force is preferably at least 20 Hz, in particular at least 30 Hz. Alternatively or additionally, the oscillation frequency is preferably at most 70 Hz, but rather at most 60 Hz, particularly preferably at most 50 Hz. At higher frequencies, a stiffer fiber composite laying device is necessary. Higher frequencies are therefore possible but generally not advantageous.

[0024] It is advantageous if the oscillating shear force has a shear force amplitude of at least 3 N, in particular at least 5 minutes. Preferably, the shear force amplitude is at most 50 N, in particular at most 40 Newtons, and particularly preferably at most 30 N.

[0025] Preferably, the slippage between the consolidation roller, on the one hand, and the fiber composite material, on the other hand, is at most 1 mm, in particular at most 0.5 mm. Particularly preferably, the slippage is essentially zero. The characteristic that the slippage is essentially zero is understood in particular to mean that the slippage is so small that it has no noticeable influence on the surface of the fiber composite material facing away from the metal surface. The slippage is the maximum distance by which a point on the fiber composite material that is in contact with the consolidation roller moves relative to the adjacent surface of the consolidation roller.

[0026] It is advantageous if the consolidation roller has a surface that consists at least partially of a polymer, in particular a plastic. For example, the consolidation roller has a surface made of polyurethane, silicone, or rubber.

[0027] Preferably, a coefficient of static friction p between the structuring roller and the fiber composite material is at least p = 0.1 and / or at most p = 0.5.

[0028] It is advantageous if the oscillating shear force is applied in such a way that the fiber composite material does not form wrinkles.

[0029] The matrix material can be a thermoset or a thermoplastic. It is generally advantageous if the matrix material comprises or consists of a thermoplastic.

[0030] The metal surface may, for example, be part of an automobile part, an aircraft, a ship, a sporting goods item or any other object or component.

[0031] For example, the metal surface is the surface of an object whose metal surface consists predominantly of steel, aluminum, or zinc. In particular, the object can be constructed of an alloy. This alloy is preferably steel or an aluminum alloy.

[0032] Preferably, the shear force is exerted at the laying front by means of a consolidation roller, by means of which the consolidation force is applied. In other words, the consolidation roller applies both the consolidation force and the shear force to the fiber composite material. Preferably, the method comprises the step of introducing a microstructure into the metal surface by irradiation with a laser beam. Preferably, the laser beam is irradiated onto the metal surface at a first angle of incidence. This first angle of incidence is preferably at least 10°, but a first angle of incidence of at least 60°, in particular at least 70°, is particularly favorable. It is favorable if the angle of incidence is at most 85°.

[0033] The intensity of the laser beam is preferably selected so that the material of the metal surface melts and / or vaporizes locally. The irradiation creates micro-recesses in the metal surface that extend along the laser beam and are directed at an angle of incidence to the normal to the metal surface.

[0034] The angle of incidence is measured in the plane along which the fiber composite material is applied.

[0035] According to a preferred embodiment, the introduction of the microstructure into the metal surface comprises the step of irradiating the metal surface with a laser beam at a second angle of incidence. This second angle of incidence is preferably at most 170°, but in particular at most 120°, in particular at most 110°. It is advantageous if the second angle of incidence is at least 95°.

[0036] In other words, the microstructure is preferably created by irradiation from two different directions. By applying the oscillating shear force, matrix material can be introduced into the micro-recesses in the metal surface. If, as provided in a preferred embodiment, the angle of incidence deviates from the normal direction, the matrix material forms indentations in the micro-recesses, forming undercuts. This results in a particularly strong, material-to-material and form-fitting connection between the metal surface and the fiber composite material.

[0037] Alternatively, the microstructure can be introduced into the metal surface, for example by means of a roller, in particular a mandrel roller, wherein the roller preferably points at an angle of inclination to the metal surface which corresponds to the above-mentioned first angle of incidence or the second angle of incidence.

[0038] Preferably, the micro-recesses are spaced apart from one another with respect to the laying direction by a distance of at most 1000 pm, in particular at most 500 pm. Preferably, the distance is at least 25 pm.

[0039] The depth of the micro-recesses is preferably at least 20 pm, in particular at least 50 pm. The depth is preferably at most 500 pm, in particular at most 300 pm.

[0040] Preferably, the shear force oscillates along a laying direction in which the laying front moves. Preferably, the fiber composite material can be laid along a linear path without undulations occurring along the laying direction.

[0041] It is also possible, however, for the shear force to oscillate perpendicular to the laying direction. However, this can lead to the aforementioned undulations, which are only desirable in exceptional cases.

[0042] According to a preferred embodiment, the method comprises the step of heating the fiber composite material, particularly in the area of ​​the laying front. This is done in particular using a heat source. The heat source can be, for example, a hot gas blower, a light source, or a flame. The light source can be, for example, a laser, particularly a diode laser, or a flash lamp. The flame is, for example, a hydrogen flame.

[0043] Preferably, the fiber composite material is heated to a temperature high enough to reduce the viscosity of the matrix material to such an extent that the matrix material penetrates into the micro-recesses due to the oscillating shear force. At a minimum, the matrix material penetrates into at least 50% of the volume of the micro-recesses. This value is determined by producing a cross-section and by measuring the area of ​​the matrix material relative to the total cross-sectional area of ​​the micro-recesses. The method is preferably carried out using a fiber composite material laying device according to the invention.

[0044] The fiber composite laying device preferably has a consolidation roller designed to oscillate in the circumferential direction. Alternatively or additionally, the consolidation roller can be designed to oscillate along a rotational axis of the consolidation roller, but this is only advantageous in exceptional cases.

[0045] According to the invention, there is also provided a manufacturing device for producing a fiber composite-metal workpiece, in particular a metal workpiece reinforced with a fiber composite material, comprising (a) a fiber composite laying device according to the invention, (b) a structuring device, in particular a laser structuring device, which is designed to introduce a microstructure into a metal surface of a component with a metal surface, and (c) a transport device which is designed to transport the component from the structuring device to the fiber composite laying device, which is designed to produce the fiber composite-metal workpiece by applying a fiber composite material to the component.

[0046] Preferably, the structuring device is designed to introduce a microstructure into the metal surface by irradiation with a laser beam. Preferably, the structuring device is designed to automatically irradiate the metal surface with a laser beam at the aforementioned first angle of incidence and also at the aforementioned second angle of incidence. In this way, a metal surface structured in two directions is created.

[0047] The invention is explained in more detail below with reference to the accompanying drawings.

[0048] Figure 1 a is a perspective view of a fiber composite laying device according to the invention

[0049] Figure 1b shows a schematic cross-section through the consolidation roller and the component, Figure 2a shows a schematic perspective view of a part of the fiber composite laying device with a heat source,

[0050] Figure 2b is a schematic view of the consolidation roller for generating the oscillating shear force and

[0051] Figure 3 shows schematically a manufacturing device according to the invention which has a structuring device.

[0052] Figure 1a shows a fiber composite laying device 10 according to the invention, which has an application head 12 for applying a fiber composite material 14 to a component 16. The application head 12 comprises a consolidation roller 18 for exerting a consolidation force FK on the fiber composite material 14, acting on a metal surface 20 of the component 16.

[0053] The application head 12 is designed to apply the fiber composite material 14 in a laying direction LR. The application head 12 can, as shown in Figure 1a, be guided along at least one guide 22.1, 22.2. In the present case, the guides 22.1, 22.2 are designed as a portal. However, it is also possible for the application head 12 to be guided along the metal surface 20 by a robot, which preferably has at least two axes.

[0054] Figure 1 b schematically shows a cross section through the consolidation roller 18, which rotates about a rotation axis D. It can be seen that the component 16 has a microstructure in its metal surface 20, which has a plurality of micro-recesses 24. i (i=1, 2, ...).

[0055] The fiber composite material 14 consists of a schematically drawn textile 26 in a matrix 28 made of matrix material 29. For example, the matrix material is a thermoplastic resin.

[0056] The consolidation roller 18 performs a substantially constant rotational movement at an angular velocity o. At a laying front 30, the fiber composite material 14 comes into contact with the metal surface 14 and is pressed by the consolidation roller 18 onto the metal surface 20. In the area of ​​the laying front 30, the consolidation roller 18 applies a shear force Fs that oscillates. For example, the shear force Fs(t) = Fs,o * sin(27tfst) with a shear force amplitude Fs,o and an oscillation frequency fs.

[0057] By applying the oscillating shear force Fs(t), a portion of the matrix material 29 is pressed into the micro-recesses 24 i. This results in a firm, form-fitting and material-locking connection between the fiber composite material 14 and the metal surface 20. The consolidation roller 18, and thus in particular the application head 12, move forward at a laying speed v.

[0058] Figure 2a shows a perspective view of the consolidation roller 18, in which a heat source 32 is shown. The heat source 32 is arranged to heat the fiber composite material 14 in the region of the laying front 30. In particular, the heat source 32 is designed to heat the fiber composite material 14 exclusively in the region of the laying front 30. The heat source 32 can be, for example, a diode laser.

[0059] The fiber composite laying device 10 has a shear force generator 34, which, as shown in Figure 2b, can be formed on the consolidation roller 18. The shear force generator 34 has a first eccentric 36.1 and a second eccentric 36.2. The eccentrics are rotatably mounted about respective axes of rotation D36.1, D36.2. The axis of rotation D of the consolidation roller lies on a straight line G with the axes of rotation D36.1, D36.2. It is also advantageous if, as in the present case, the distances of the axes of rotation D36.1, D36.2 from the axis of rotation are each equal. The eccentrics 36.1, 36.2 are driven by a motor (not shown).

[0060] The eccentric 36.1 has a first center of mass rr)36.i, the eccentric 36.2 has a second center of mass rri36.2. The eccentrics 36.1, 36.2 are driven such that the second center of mass rri36.2 lies on the straight line G precisely when the first center of mass mse.-i also lies on the straight line G. This results in a periodically fluctuating torque M acting on the consolidation roller 18. This causes the periodically fluctuating shear force Fs. Figure 3 schematically shows a manufacturing device 38 according to the invention, which has a structuring device 40. The structuring device 40 can have one or two (or more) lasers 42.1, 42.2, which irradiate the metal surface 20 with a respective laser beam 44.1, 44.2 such that the micro-recesses 24.i (see Figure 1b) are created. The thus processed components 16 are transported to the fiber composite material laying device 10 by means of a conveyor system 46.The conveyor can be a conveyor belt, a robot or a vehicle, such as an industrial truck.

[0061] The first laser beam 44.1 falls onto the metal surface 20 at a first angle of incidence ai. The second laser beam 44.2 falls onto the metal surface 20 at a second angle of incidence 02. The two angles of incidence can be of equal magnitude with respect to a normal N to the metal surface 20. This creates the micro-recesses 24.i.

[0062] The recesses 24.1, 24.3, 24.5, ... created by the first laser beam 44.1 have an extension direction Ei (see Figure 1 b), which runs at a first extension angle si to the normal N on the metal surface 20. The recesses 24.2, 24.4, 24.6, ... created by the second laser beam 44.2 have an extension direction E2, which runs at a second extension angle S2 to the normal N on the metal surface 20. The two extension angles can be equal in magnitude. However, they extend in different directions away from the normal N with respect to the plane perpendicular to the rotation axis D.

[0063] The micro-recesses 24 i are spaced apart by a distance a24 from each other with respect to the laying direction LR. For example, 25 pm < a24 < 500 pm.

[0064] The micro-recesses 24.i have an average depth T24 of, for example, 25 pm < T24 — 500 pm. List of reference symbols

[0065] 10 Fiber composite laying device 44 Laser beam 46 Conveyor system

[0066] 12 Application head

[0067] 14 Fiber composite material a angle of incidence

[0068] 16 Component s extension angle

[0069] 18 Consolidation role oi8 Angular velocity

[0070] 20 Metal surface a24 Distance of the micro-recesses

[0071] 22 Guide D Rotary axis

[0072] 24 micro-recesses E extension direction

[0073] 26 Textile FK Consolidation Power

[0074] 28 Matrix Fs Shear force

[0075] 29 Matrix material Fs,o Shear force amplitude

[0076] G Straight

[0077] 30 Legefront i Running Index

[0078] 32 Heat source rri36 Center of mass

[0079] 34 Shear force generator M torque

[0080] 36 Eccentric N Normal

[0081] 38 Manufacturing device LR laying direction

[0082] T24 Depth of micro-recesses

[0083] 40 Structuring device v Laying speed

[0084] 42 lasers

Claims

Patent claims 1. Method for joining a fiber composite material (14) with a Metal surface (20) of a component (16), comprising the steps: (a) applying the fiber composite material (14), which has a flat textile (26) and a matrix (28) made of matrix material (29) embedding the textile (26), to the metal surface (20), and (b) exerting a consolidation force (FK) directed towards the metal surface (20) on the fibre composite material (14), characterized in that (c) the metal surface (20) has a microstructure with a plurality of micro-recesses (24), and that (d) the method comprises the step Applying an oscillating shear force (Fs) to the fiber composite material (14) so ​​that matrix material (29) is introduced into the micro-recesses (24).

2. Method according to claim 1, characterized in that the shear force (Fs) (a) at a laying front (30) where the fiber composite material (14) comes into contact with the metal surface (20), and / or (b) is applied by means of a consolidation roller (18) by means of which the consolidation force (FK) is exerted.

3. Method according to one of the preceding claims, characterized by the steps: (a) introducing a microstructure into the metal surface (20) by irradiation with a laser beam (44), (b) wherein the laser beam (44) falls on the metal surface (20) at a first angle of incidence (a) and (c) wherein the laser beam (44) is incident on the metal surface (20) at a second angle of incidence (a) which differs from the first angle of incidence (a).

4. Method according to one of the preceding claims, characterized in that the shear force (Fs) (a) along a laying direction in which the laying front (30) moves, and / or (b) oscillates transversely to the laying direction.

5. Method according to one of the preceding claims, characterized by the step of heating the fiber composite material (14).

6. Fiber composite laying device (10) for connecting a fiber composite material (14) to a metal surface (20), comprising: (a) an application head (12) for applying the fiber composite material (14) to the metal surface (20) and (b) a consolidation roller (18) for exerting a consolidation force (FK) directed towards the metal surface (20) onto the fibre composite material (14), (c) wherein the consolidation roller (18) is designed to apply an oscillating shear force (Fs) to the fiber composite material (14).

7. Fiber composite material laying device (10) according to claim 6, characterized in that the consolidation roller (18) is formed (a) for oscillating in the circumferential direction and / or (b) for oscillating along a rotation axis (D) of the consolidation roller (18).

8. Manufacturing device (38) for producing a fiber composite metal workpiece, with (a) a fiber composite laying device (10) according to claim 6 or 7, (b) a structuring device (40), in particular a laser structuring device, which is designed to introduce a microstructure into a metal surface of a component (16), and (c) a transport device arranged to transport the component (16) from the structuring device (40) to the fiber composite material laying device.

9. Manufacturing device (38) according to claim 8, characterized in that the structuring device (40) is designed to introduce a microstructure into the metal surface (20) by irradiation with a laser beam (44).

10. Manufacturing device (38) according to claim 9, characterized in that the structuring device (40) is designed for automatically irradiating the metal surface (20) with a laser beam (44) at a first angle of incidence (α) and also at a second angle of incidence (α) which differs from the first angle of incidence (α).

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