DE102014000194A1 - Method for producing and connecting at least two fiber-reinforced components and component thereof - Google Patents

Abstract

A method for producing and joining at least two fiber-reinforced components, comprising providing at least two components of fibers which are embedded in a first matrix except at a connection region and at a connection surface, not parallel to the same oriented or not parallel to the same oriented main extension direction, exposing, assembling the components such that the exposed fibers of the components at least partially overlap, soaking the fibers in their overlap region with a second matrix and curing the second matrix in the overlap region and component formed from at least two fiber reinforced components passing over a joint zone are interconnected, in which overlap at least partially emerging from the respective interfaces of the respective component and the joining zone fibers.

Description

The present invention relates to a method for producing and connecting at least two fiber-reinforced components as well as a component which is formed from at least two fiber-reinforced components, which are interconnected via a joining zone.

The example of the bonding of fiber-reinforced plastic components, the problem underlying the present invention will be described. The bonding of fiber-reinforced plastic components, due to a number of positive characteristics, constitutes a joining process whose further dissemination in use is desirable. Thus, bonded connections are characterized by damage tolerant properties, crack stop function, a low weight of the connection and an additional sealing function and are to be considered as a result of the flat power transmission as a convenient connection especially for thin-walled composite components. At the same time, many classic bonds made in Secondary Bonding (two cured mating parts are combined with an additional adhesive material that makes the connection) have a number of weak points as well. Thus, the characteristic values of the bond are often relatively low for loads which are unlike the thrust load normally desired. Also, many plastics and the adhesive bond between the adhesive and the bonding partner surface tend to cause severe degradation under continued environmental conditions, which further restricts the range of applications. To counteract these weaknesses, the adhesive surfaces are often enlarged, which means an increase in the overlap zone and thus an increase in cost and weight. Also, some properties can be improved by suitable surfaces before treatment measures (eg, roughening surface for mechanical adhesion and surface enlargement). Alternatively, additional joining elements (also known as "fear rivets") are used for transferring unfavorably attacking forces and as additional reinforcement and design improvements in the area of the joint, for example by shanks of the joining partners or with the aid of tabs or local crimping.

The described methods are all associated with an additional expense, which manifests itself as a weight or cost disadvantage. The essential problem of the adhesive bond, the relatively poor mechanical properties, especially in unfavorable load directions and after long aging under extreme weather conditions, is not solved.

The present invention is therefore based on the object of improving the mechanical properties during joining, in particular bonding, of fiber-reinforced components.

• – Bereitstellen von mindestens zwei Bauteilen aus Fasern, die außer in einem Verbindungsbereich in eine erste Matrix eingebettet sind und an einer Verbindungsoberfläche, nicht parallel zu selbiger orientiert oder mit nicht parallel zu selbiger orientierter Haupterstreckungsrichtung, freiliegen,
• – Zusammenfügen der Bauteile derart, dass die freiliegenden Fasern der Bauteile zumindest teilweise überlappen, insbesondere in einer Art, dass keine nicht von Fasern durchstoßene Ebene mehr zwischen den Bauteilen existiert,
• – Durchtränken der Fasern im Verbindungsbereich mit einer zweiten Matrix und
• – Aushärten der zweiten Matrix im Verbindungsbereich.

According to the invention, this object is achieved according to a first aspect by a method for producing and connecting at least two fiber-reinforced components, comprising

• Providing at least two components of fibers which are embedded in a first matrix except in one connection region and are exposed on a connection surface, not oriented parallel thereto or with a main extension direction that is not parallel to the same,
• Joining the components in such a way that the exposed fibers of the components at least partially overlap, in particular in such a way that no non-fiber-pierced plane no longer exists between the components,
• - Soaking the fibers in the connecting region with a second matrix and
• - Hardening of the second matrix in the connection area.

Furthermore, this object is achieved by a component which is formed from at least two fiber-reinforced components, which are interconnected via a joining zone, characterized in that overlap in the joining zone from the respective boundary surfaces of the respective component and the joining zone emerging fibers at least partially.

According to a particular embodiment of the method, the components are manufactured separately prior to the step of providing the at least two components.

In particular, it can be provided that the at least two components are produced by impregnating the fibers with the first matrix only in a partial area and curing the first matrix.

In this case, the fibers can be impregnated with the first matrix only in a partial area, by preferably filling material being previously filled into the connection area.

In particular, it may be provided that the filling material is removed before the components are assembled.

Alternatively, the fibers may only be impregnated with the first matrix in a partial area, preferably by first impregnating the connecting area with a third matrix which is later removable from the fibers or which cures at a higher temperature than the first matrix.

Again alternatively, the fibers may be soaked in only a portion of the first matrix by compressing the fibers in the bonding area during soaking, and preferably also during curing.

According to an alternative embodiment, the at least two components can be produced by impregnating the fibers completely with the first matrix, then reversing the impregnation in the connection region and curing the first matrix.

In particular, it can be provided that by cooling the first matrix in the connecting region, a local curing thereof during impregnation or after soaking is prevented and the impregnation in the connection region is reversed by removing the first matrix which has not hardened there.

Again, alternatively, the at least two components can be made by fully impregnating the fibers with the first limited-polymerization matrix, reshaping them, adding them to a prepreg structure, and subsequently curing them together.

In particular, curing can be thermally suppressed in the connection region for limited polymerization.

Advantageously, the fibers are mechanically stabilized during assembly of the components or before the impregnation of the fibers in their overlap region.

Finally, it may be provided, in particular, that the fibers are stabilized by introducing at least one spacer or by a high-viscosity adhesive film.

The invention is based on the surprising finding that the mechanical properties of the joining zone can be improved by the use of fibers in the joining zone and in particular in an interlocking manner.

The process is particularly suitable for bonding fiber-reinforced thermoset matrix components but can be used with appropriate modifications for all fiber reinforced materials.

Further features and advantages of the invention will become apparent from the appended claims and the following description in which two embodiments are explained with reference to the schematic drawings. Showing:

1 to 5 several steps of a method of manufacturing and joining two fiber reinforced components according to a particular embodiment of the present invention; and

6 to 10 several steps of a method for producing and joining two fiber-reinforced components according to another particular embodiment of the present invention.

While in the prior art, in an adhesive layer itself, a plane consisting of pure adhesive remains, according to the present invention, in at least one particular embodiment, this "unreinforced" plane is provided with reinforcing fibers with an orientation outside this plane, i. H. provided with reinforcing fibers which are oriented out of the plane or point out of this, wherein the reinforcing fibers reach into the actual components. For this purpose, the fibers should either be unwetted at the moment of bonding or, as part of the bonding process, a shift of the fiber-enclosing matrix material should take place. The separate production of individual components from which a larger structure is then produced by joining methods, such as bonding, but is often unavoidable in the art for manufacturing reasons. At this point, the method according to the invention, at least in one particular embodiment, is now based on the fact that the impregnation (impregnation) / curing of the adding components is intentionally incomplete. For example, the parts or connecting regions of a component which should later be in contact with a second component (joint partner) are either selectively impregnated with the matrix system or the impregnation is carried out in such a way that it is locally reversible, without the Damage the forest. Another alternative is, for example, the impregnation with limited polymerization, so that a forming process is subsequently possible.

• 1a) Lokales Kühlen verhindert die Aushärtung der ersten Matrix 3 im gekühlten Verbindungsbereich 8, so dass das im Verbindungsbereich 8 flüssige Harzsystem entfernt werden kann. Die dann freiliegenden Fasern 12 können dann – wie weiter unten beschrieben wird – zur Ausprägung der faserverstärkten Fügeschicht genutzt werden.
• 1b) Alternativ kann das in dem Verbindungsbereich 8 vorimprägnierte Fasermaterial – in Folge zum Beispiel einer thermisch unterdrückten Aushärtung in dem Verbindungsbereich 8 – mit dem hochviskosen Harzsystem umgeformt und an andere Prepregstrukturen gefügt und in einem folgenden Arbeitsschritt gemeinsam ausgehärtet werden. Dies ist sowohl bei Prepregprozessen, klassischen Injektions- und Infusionsverfahren, aber auch beispielsweise bei Pultrusionsverfahren anwendbar.
• 2) Lokales Befüllen mit inerten Gasen, Flüssigkeiten oder hochviskosen Dichtmassen (Platzhalter), durch welche lokal ein Bereich eines Bauteils im Injektions- oder Infusionsprozess nicht oder nur teilweise mit der ersten Matrix getränkt wird. Dadurch ergibt sich am Bauteil lokal ein Bereich (Verbindungsbereich) nicht getränkter Fasern, der in der weiteren Prozesskette zur Anbindung weiterer Strukturen geeignet ist. Je nach verwendetem Füllmaterial wird dieses während des Prozesses entweder durch Dichteunterschiede oder durch die hohe Zähflüssigkeit an Ort und Stelle gehalten.
• 3) Lokales Imprägnieren mit einer dritten Matrix (Sekundärmatrix), die in einem weiteren Schritt nach Entformen des Werkstücks (Bauteils) wieder von den Fasern entfernt werden kann, ohne die Reststruktur zu schädigen, oder alternativ die Nutzung einer dritten Matrix (Sekundärmatrix), die bei einer höheren Temperatur aushärtet. Die lokale Imprägnierung kann dabei auch vor dem Einlegen der Fasern in die Form oder auch vor dem Injektions- oder Infusionsprozess, bei dem das eigentliche Matrixmaterial eingebracht wird, erfolgen. Das Entfernen der dritten Matrix (Sekundärmatrix) kann dabei zum Beispiel über chemische Prozesse erreicht werden. Alternativ kann das Aushärten der dritten Matrix (Sekundärmatrix) nach einem Umform- oder Fügeprozess durchgeführt werden.
• 4) Durch lokales Klemmen oder Pressen o. ä. der trockenen Fasern (ohne Matrix) in dem späteren Verbindungsbereich mittels eines Klemmelements 5 kann die Kompaktierung stark erhöht werden, wodurch die Permeabilität im Textil soweit absinkt, dass ein Durchtränken in diesem Bereich 6 vermieden werden kann, während die niederviskose Matrix den ungeklemmten Bereich der Fasern benetzt. Nach einem Aushärteschritt liegen damit freie Faserbereiche vor, die – wie unten weiter beschrieben – für Fügeprozesse genutzt werden können.

Both at the 1 to 5 as well as in the 6 to 10 First of all, the methods described are dry fibers 12 in a cavity 2 in a tool 1 filled (see 1 for example). The ones with the dry fibers 12 filled cavity 2 comes with a first matrix 3 filled (s. 2 respectively. 7 ). But this is only a part 13 impregnated the fibers or the component to be produced and then completely cured. In the later connection area 8th (S. 3 respectively. 8th ), on the other hand, the impregnation or hardening is prevented by one of the following steps or one of the following steps:

• 1a) Local cooling prevents the curing of the first matrix 3 in the cooled connection area 8th so that's in the connection area 8th liquid resin system can be removed. The then exposed fibers 12 can then - as will be described below - be used to express the fiber-reinforced joining layer.
• 1b) Alternatively, this can be done in the connection area 8th Preimpregnated fiber material - in consequence, for example, a thermally suppressed curing in the connection area 8th - Formed with the high-viscosity resin system and added to other prepreg structures and cured together in a subsequent step. This is applicable both in prepreg processes, classical injection and infusion processes, but also, for example, in pultrusion processes.
• 2) Local filling with inert gases, liquids or highly viscous sealants (placeholders), through which locally a portion of a component in the injection or infusion process is not or only partially impregnated with the first matrix. As a result, a region (connection region) of non-impregnated fibers, which is suitable for connecting further structures in the further process chain, results locally on the component. Depending on the filler used, it will be held in place during the process either by density differences or by the high viscosity.
• 3) local impregnation with a third matrix (secondary matrix), which can be removed in a further step after removal of the workpiece (component) again from the fibers without damaging the residual structure, or alternatively the use of a third matrix (secondary matrix), the hardens at a higher temperature. The local impregnation can also take place before the fibers are inserted into the mold or else prior to the injection or infusion process in which the actual matrix material is introduced. The removal of the third matrix (secondary matrix) can be achieved, for example, via chemical processes. Alternatively, the curing of the third matrix (secondary matrix) can be carried out after a forming or joining process.
• 4) By local clamping or pressing or the like of the dry fibers (without matrix) in the later connection area by means of a clamping member 5 the compaction can be greatly increased, whereby the permeability in the textile decreases to the extent that a soaking in this area 6 can be avoided while the low-viscosity matrix wets the unclamped area of the fibers. After a curing step, there are thus free fiber areas which, as described further below, can be used for joining processes.

2 shows the variant described above under 1a), while the 6 and 7 show the variant described above under 4).

After completion of a demolding process and if necessary removal of the previously described placeholders (eg uncured resin system, pressure or other fluid, secondary matrix) is then, as in 3 respectively. 8th shown a component 7 which identifies substantially a normal fiber reinforced structure in the joint area 8th but dry, that is not covered by the first matrix fibers 12 having.

The orientation of the connection area 8th located fibers 12 is of great importance for the reinforcing effect in the later resulting adhesive layer. If the target is a Z-gain, ie a gain, where the fibers are not parallel to the plane of the boundary layer 14 between the adhesive and joining partner (component), but are oriented at an angle α ≠ 0, so this has to be adjusted depending on the orientation of the dry fibers. This can be done, for example, by local separation, ie cutting a partially enclosed by a matrix textile or by a brushing process in which individual fibers are locally destroyed and erected, as well as for example by introducing additional reinforcing fibers in the uncured compound region 8th through a one-sided tufting process.

Like in the 4 or the 9 Subsequently, two components prepared in this way (joining partners) 7 . 7 that are not necessarily identical in geometry, positioned to each other. The erected fibers 12 Now, some of them mesh with each other, ie there is no plane in the area of the joining zone or joint which is completely free of fibers.

Like in the 5 or in the 10 indicated, become the dry fibers 12 now infiltrated in a further processing step, ie, that area not previously filled by a matrix, such as a first matrix or a second matrix 10 (Connection area) is soaked. The second matrix may be different from the first matrix.

Depending on the length, quantity and stability of the compound surfaces 16 carrying fibers 12 It may be advisable to stabilize them, for example, by using remaining in each component spacers (not shown). With very many short fibers with approximately perpendicular orientation to the bonding surface, however, the use of a highly viscous adhesive film is conceivable, wherein the fibers of the components (joining partners) can be entangled either during the curing process by additionally introduced pressure or the adhesive film itself introduced over perpendicular to its surface Fibers which, when the film melts under pressure then diffuse with those from the bonding surfaces 16 of the components 7 . 7 mix protruding fibers.

As further in the 5 or the 10 shown, the product is then as in the field 10 shown, a structure with a joining zone, which has fibers at the splices, which are the interfaces 14 penetrate yourself.

In summary, connections between fiber-reinforced components which are likewise fiber-reinforced can be produced with the described methods. In contrast to normal bonding method, the fiber reinforcement is made possible perpendicular to the plane of the joining zone, whereby the known good properties of fiber reinforced structures can be used even when unfavorable for unreinforced bonding load directions. The fibers penetrate the interfaces between the joining partner and the adhesive. As a result, items of lesser complexity can be fabricated in simpler manageable processes and then assembled into highly complex, complex structures, without the joining zone acting as a weak point due to the factors described above, in which it has been the case so far. Additional measures, such as the use of further joining elements, complex surface treatments, Schäftungen or other constructive supportive measures can be avoided or at least reduced.

With the present invention, it is achieved, at least in a particular embodiment, that the region of the joining zone or point also has a fiber reinforcement, which ensures an improvement in the mechanical properties, in particular when the stresses are unfavorable for the bonding. Thus, the outstanding specific properties of fiber-reinforced plastics are also used for the bond itself.

The features of the invention disclosed in the foregoing description, in the drawing and in the claims may be essential both individually and in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

1

Tool

2

cavity

3

first matrix

5

clamping element

6

Area

7

component

8th

connecting area

10

Area

12

fibers

13

part

14

interface

16

connecting surfaces

α

angle

Claims (14)

Method for producing and connecting at least two fiber-reinforced components ( 7 . 7 ), comprising - providing at least two components ( 7 . 7 ) of fibers ( 12 ), which except in a connection area ( 8th ) into a first matrix ( 3 ) and at a connection surface ( 16 ), not parallel to the same oriented or with not parallel to selbiger oriented main extension direction, exposed, - Assembling of the components ( 7 . 7 ) such that the exposed fibers ( 12 ) of the components at least partially overlap, in particular in such a way that no non-fiber-pierced plane exists between the components, - soaking the fibers ( 12 ) in the connection region with a second matrix and - hardening of the second matrix in the connection region. A method according to claim 1, characterized in that before the step of providing the at least two components, the components ( 7 . 7 ) are prepared separately. Method according to claim 2, characterized in that the at least two components ( 7 . 7 ) are prepared by the fibers ( 12 ) only in a subarea ( 13 ) with the first matrix ( 3 ) and the first matrix ( 3 ) is cured. Method according to claim 3, characterized in that the fibers ( 12 ) only in a subarea ( 13 ) with the first matrix ( 3 ) are preferably saturated by filling previously filling material in the connection area. A method according to claim 4, characterized in that prior to assembly of the components ( 7 . 7 ) the filling material is removed. Method according to claim 3, characterized in that the fibers ( 12 ) only in a subarea ( 13 ) with the first matrix ( 3 ) are impregnated by preferably before the connecting region is impregnated with a third matrix, which is later removable from the fibers or at a higher temperature than the first matrix hardens. Method according to claim 3, characterized in that the fibers ( 12 ) only in a subarea ( 13 ) with the first matrix ( 3 ) are impregnated by compressing the fibers in the joint area during impregnation, and preferably also during curing. Method according to claim 2, characterized in that the at least two components ( 7 . 7 ) are prepared by the fibers ( 12 ) completely with the first matrix ( 3 ), after which the saturation in the connection area is reversed and the first matrix is cured. Method according to claim 8, characterized in that by cooling the first matrix ( 3 ) in the connection area ( 8th ) a local hardening of the same during impregnation or after soaking is prevented and the impregnation in the connection area ( 8th ) is reversed by removing the uncured first matrix there. Method according to claim 2, characterized in that the at least two components ( 7 . 7 ) are prepared by the fibers ( 12 ) completely impregnated with the first matrix with limited polymerization, reshaped, joined to a prepreg structure and subsequently cured together. A method according to claim 10, characterized in that for limited polymerization in the bonding area curing is thermally suppressed. Method according to one of the preceding claims, characterized in that the fibers are mechanically stabilized during assembly of the components or before the impregnation of the fibers in their overlapping region. A method according to claim 12, characterized in that the fibers are stabilized by introducing at least one spacer or a high-viscosity adhesive film. Component consisting of at least two fiber-reinforced components ( 7 . 7 ) is formed, which are interconnected via a joining zone, characterized in that in the joining zone from the respective interfaces ( 14 ) of the respective component ( 7 . 7 ) and the joining zone emerging fibers overlap at least partially.

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