EP3013564A1

EP3013564A1 - Method and shaping tool for producing a fibre composite hollow component

Info

Publication number: EP3013564A1
Application number: EP14731977.6A
Authority: EP
Inventors: Hubert Burlefinger; Wolfgang Gruber; Franz Maidl; Bruno Niesner; Thomas Paßreiter
Original assignee: Bayerische Motoren Werke AG
Current assignee: Bayerische Motoren Werke AG
Priority date: 2013-06-28
Filing date: 2014-06-24
Publication date: 2016-05-04
Also published as: WO2014206979A1; DE102013212694A1

Abstract

The invention concerns a method and a shaping tool for producing a fibre composite hollow component. The method comprises the following steps: (a) preparing an inflatable support structure (2); (b) applying fibrous material (4) to the support structure (2) in order to produce a preform (1); (c) introducing the preform (1) on the support structure (2) into a shaping tool (6); and (d) generating excess pressure (P) inside the support structure (2) such that the preform (1) is urged by the support structure (2) against shaping faces (7a, 8a) of the shaping tool (6). According to the invention, the support structure (2) comprises at least in sections a corrugated hose (3) or a corrugated hose-like element. The invention further concerns a shaping tool for producing a fibre composite hollow component from a preform comprising a fibrous material (4) which is applied to an inflatable support structure (2), the shaping tool (6) being designed and arranged to accommodate the preform (1) on the support structure (2) and introduce excess pressure (P) into the interior of the support structure (2).

Description

description

Method and forming tool

for producing a fiber composite hollow component

The present invention relates to a method and a shaping tool for producing a fiber composite hollow component. It is known to produce CFRP hollow components through the use of contoured three-dimensional support cores (e.g., sand cores, wax cores, etc.) or inflatable tubes, tube bladders, and inflatable blow mold components. In this case, a preform is first produced by fiber material is applied to a provided support structure. The preform on the support structure is then introduced into a forming tool, and by use of the illustrated aids, the reinforcing fibers used during the process are pressed and shaped on forming surfaces of the forming tool. Depending on the type of process, the reinforcing fibers are already provided in advance with a matrix system. Alternatively, the matrix is injected into the closed forming tool (RTM method). When using support cores based on inflatable elements while the tightness of the support cores is ensured by appropriate measures. After hardening of the reinforcing matrix, the end component can then be removed from the shaping tool.

Contoured support cores with a usually three-dimensional geometry can essentially only be occupied by discontinuous processes with reinforcing fibers. For example, fiber preforms or preforms can either be laid on the cores or inserted directly into the later forming tool. Alternatively, the contoured three-dimensional support cores can also be provided with reinforcing fibers by means of a braiding technology. This is initially also a discontinuous production process. An automation of the manufacturing process is in a first approach, for example possible in that several cores are positioned and braided together in a circular path.

An object of the present invention is to provide a method and a molding tool which avoids the disadvantages of the prior art. In particular, an object of the present invention is to provide a method and a shaping tool for producing a fiber composite hollow component using an inflatable support structure, which with regard to at least one of the aspects of process safety, automation, flexibility in the dimensioning of the fiber composite hollow component, a handling and contouring of the preform or the hollow component, the design effort, the cleaning effort and tooling costs to improve. The above object is achieved at least in some aspects by a method according to the invention with the features of claim 1 and by a forming tool having the features of claim 10. Here are features and details that are described in connection with the inventive method, also in connection with the shaping tool according to the invention and in each case vice versa and alternately, so that with respect to the disclosure of the individual aspects of the invention is always reciprocally referred to or can be.

According to a first aspect of the present invention, a method for producing a fiber composite hollow component comprising the steps:

a) providing an inflatable support structure;

b) applying fiber material to the support structure to produce a preform;

c) introducing the preform on the support structure into a forming tool;

d) generating an overpressure within the support structure such that the preform is pressed by the support structure on shaping surfaces of the forming tool,

proposed. According to the invention, the support structure at least in sections a corrugated hose or a corrugated hose-like element. The method may in particular for the production of a fiber composite hollow component for the Vehicle construction, preferably the automotive or motorcycle construction to be adapted. In the context of the invention, a corrugated tube is understood to be a tubular structure, in particular made of a plastic (thermoplastic, PVC, etc.), which has a wave-like or corrugated outer wall in the broadest sense; In particular, commercially available corrugated hoses are also suitable for use in the method according to the invention. The outer wall wave form may be coiled or annular, and allows for axial extensibility of the support structure at least in the respective portion or in total, without significantly changing the outer radius of the corrugated tube. As a result, the preform on the support structure (the corrugated hose) remains dimensionally stable, even if an extension of the corrugated hose takes place. The wave structure also provides a degree of stiffening and bearing capacity despite comparatively low wall thickness. Therefore, the support structure is also largely free of pressure, without pressure. Nevertheless, the corrugated tube is so flexible that sufficient, technically meaningful internal pressure reaches a sufficient for the purposes of blow molding expansion and the internal pressure can be passed to the fiber material. In addition, the inventors have found that a contour formation of the preform is improved due to the axial extensibility with radial dimensional stability of the corrugated hose compared to conventional inflatable support cores, as among other things in one-sided extension of the corrugated hose and a curvature of the preform and thus the hollow component to be produced is possible. The application of the fibrous material to the support structure may include, for example, but not limited to, the braiding of long fibers, laying or winding of fiber mats, and other known techniques. The introduction of the preform into the shaping tool is preferably carried out so that the fiber material of the preform lies between the support structure and shaping surfaces of the shaping tool. After the generation of the overpressure and the associated pressing of the preform to the shaping surfaces of the forming tool, further steps known per se, such as hardening of the preform in the mold, a release of the pressure, an opening of the mold, follow Remove the component from the mold and remove the support structure.

In a preferred embodiment of the method of this aspect of the invention, during the step of applying fiber material on the support structure, the support structure held so that an axial change in length of the support structure is prevented. The holding of the support structure can be realized, for example, but not limited to, by an appropriate pulling unit (used, for example, for a method step of stretching the support structure to be described later) or the like. This enables a stable application of the fiber material on the support structure.

In a preferred development of the method of this aspect of the invention, after the application of fiber material to the carrier structure, the carrier structure with the applied fiber material is cut to a length that at least substantially corresponds to a length of the fiber composite hollow component to be produced. This means that the support structure (the corrugated hose) can be braided with excess length to be subsequently shortened to component length. On the one hand, this can facilitate the process of applying the fiber material, such as a braiding process, on the other hand, it can improve the unit of preform with carrier structure to be introduced into the forming tool in terms of handling, space, weight, etc. In other words, the preforms of several components can be formed in a single operation on a single corrugated hose, which are then cut to the appropriate length. Thus, an automation of the process can be improved, and it is also a continuous Befiechtung and lengthening possible. Alternatively, it is of course also possible to apply fiber material on a portion of the corrugated tube corresponding to an individual length of a preform, for instance between stops, in order to produce only a single preform in each case.

In a particularly preferred embodiment of the method of this aspect of the invention, after the application of the fiber material and before the introduction of the preform into the forming tool, the carrier structure is stretched in such a way that a fiber material-free end of the carrier structure is produced. In other words, the support structure is "pulled out" under the preform so that at least one free end protrudes beyond an axial length of the preform, but the preform remains supported over the entire length be clamped, wherein the fiber material can remain free. This makes it possible to carry out the blow molding so that the fiber material undergoes no excessive stresses. This can also contribute to the quality of the fiber composite hollow component. In other words, the method of this aspect of the invention may be configured such that the overpressure is introduced into the interior of the carrier structure via an end of the carrier structure that is free of fiber material. Therefore, in the forming tool no movable sliding element for initiating the pressing force is required. The cleaning effort of the tool and the tool costs overall can be reduced. In addition, process reliability is further increased.

In preferred embodiments, the method can be configured in such a way that the fiber material applied to the carrier structure is provided with a matrix material (for example impregnated or impregnated) before it is applied to the carrier structure. Equally, it is possible to provide the preform with a matrix material as a whole before it is introduced into the forming tool (for example, to impregnate it). Finally, it is also possible to inject a matrix material with already inserted preform on the forming tool. In this way, a fiber-matrix composite is produced, which can harden in the shaping tool to form a fiber composite hollow component.

According to another aspect of the present invention, a forming tool for producing a fiber composite hollow component from a preform having a fiber material applied to an inflatable support structure is proposed. The shaping tool is designed and arranged for receiving the preform on the carrier structure and introducing overpressure into the interior of the carrier structure such that the fiber material of the preform is pressed against forming surfaces of the forming tool under the effect of the overpressure by the carrier structure. According to the invention, the shaping tool has a pressure connection part with a pressure connection for introducing the overpressure, the pressure connection part having a receiving structure pointing towards an interior of the forming tool, in particular an annular groove designed to receive an axial end of the support structure, sealing means for pressure-tight sealing of the receiving structure may be preferably provided with the axial end of the support structure accommodated therein, and wherein a pressure connection line is provided which connects the interior of the forming tool to the pressure supply connection and terminates in a surface of the pressure connection part enclosed by the receiving structure.

The proposed shaping tool of this aspect of the invention is particularly suitable and designed for processing a preform made of a fiber material, which is applied to a carrier structure, which has at least a sectionally a corrugated hose or a corrugated hose-like element. In particular, it is possible or is made possible by the specially adapted design and training, one end of the support structure, which was generated by axial stretching of the corrugated hose or corrugated hose portion and is free of fiber material to receive in the receiving structure. The forming tool of this aspect of the invention is thus adapted for use in the above-described methods and therefore can realize the same advantages as well. Further features, objects and effects of the invention will become apparent from the description and the accompanying drawings. In the drawings:

Fig. 1 is a schematic representation of a preform on a support structure for illustrating a method step as an embodiment of the present invention;

FIG. 2 shows a schematic view corresponding to FIG. 1 with a carrier structure elongated in the axial direction to illustrate a further method step of this exemplary embodiment; FIG. Fig. 3 is a schematic representation of the preform with the support structure of Fig. 2 in a forming tool to illustrate a still further process step of this embodiment, wherein the forming tool itself is a further embodiment of the present invention. Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. The same component in several figures are each provided with the same reference numerals. Components and features, purposes, and effects described in reference to an exemplary embodiment are, unless expressly or implicitly excluded, to be deemed to be applicable in any other embodiment and are also to be deemed disclosed in relation to the other embodiment, even if they: not explicitly shown and / or described there. It is also to be understood that the drawings are to be understood as schematic and that no restrictions with regard to specific dimensions or size relationships should be taken from them, unless this is expressly so described.

Based on the Fign. 1 to 3, a method for producing a fiber composite hollow member as an embodiment of the present invention and a forming tool as another embodiment of the present invention will be described below.

As shown in FIG. 1, a fibrous material 4 is braided onto a provided support structure 2, which in this embodiment is a corrugated tube 3, in order to produce a preform 1. The corrugated hose 3 has a longitudinal axis L. Without limiting the generality of the corrugated hose 3 has a helically rotating shaft 3a.

Thus, FIG. 1 illustrates a method step of providing the carrier structure 2 and applying the fiber material 4 on the carrier structure 2.

1 shows a state in which the corrugated hose 3 (the support structure 2) has been stretched by tension (arrow "Z") by a predetermined amount, by stretching the corrugated hose 3 End 5 formed, which protrudes from the preform 1 (the fiber material 4) in the axial direction.

Thus, FIG. 2 shows a method step of stretching the carrier structure 2 such that an end 5 of the carrier structure 2 which is free of fiber material 4 is produced. FIG. 3 shows a schematic representation of the preform 1 on the support structure 2, which is introduced into a shaping tool 6. The forming tool 6, which is also another embodiment of the present invention, has a top 7 as a first part mold and a bottom part 8 as a second part mold. The upper part 7 and the lower part 8 each have cylindrical half-shell-shaped sections, which form shaping surfaces 7a, 8a. The shaping surfaces 7a, 8a thus define an inner space 6a of the forming tool 6 in the radial direction. The shaping surface 7a of the upper part 7 and the shaping surface 8a of the lower part 8 are adapted in shape and size to the outer contour of the preform 1.

The lower part 8 of the forming tool 6 has a pressure connection part 9 which delimits the inner space 6a of the shaping tool 6 in the axial direction. The upper part 7 and the lower part 8 with its pressure connection part 9 are adapted in shape to one another in order to enclose the closed inner space 6a. At one not shown other axial end of the forming tool 6, one or both of the upper part 7 and the lower part 8 may have a closure part which limits the inner space 6a of the forming tool 6 on that side in the axial direction. Alternatively, a lid (not shown in detail) may be provided for this purpose.

The pressure connection part 9 has a pressure connection line 9a, which connects the inner space 6a of the forming tool 6 to an environment and opens in a space 6a delimiting the inner space 6a in the axial direction of the pressure connection part 9 to the inner space 6a. In the surface 9b, a receiving structure 9c is further formed, which is formed in this embodiment as an annular groove. The receiving structure 9c is adapted to receive the free end 5 of the corrugated tube 3 (the support structure 2). A sealant 10, which in the present embodiment is an O-ring, is inserted in the receiving structure 9c to elastically receive the free end 5 of the corrugated hose 3 and thus seal an interior of the support structure 2 from the remaining interior 6a of the forming tool 6 (ie to complete gas-tight). At an outer end of the pressure communication line 9a, a pressure port 11 is provided, which is connected to a compressed air source. 3 shows a method step of introducing the preform 1, which is arranged on the carrier structure 2, into the forming tool 6 schematically. In this case, an arrow "P" symbolizes a further method step of generating an overpressure within the carrier structure 2 in such a way the preform 1 is pressed by the support structure 2 against the shaping surfaces 7a, 8a of the shaping tool 6.

In non-illustrated further steps, the preform 1 is allowed to cure within the forming tool 6. It is to be understood that the fiber material 4 of the preform 1 is impregnated with a matrix material (not shown in detail). In this case, the Matrixmateriai can be injected via channels not shown in the sub-forms 7, 8 of the forming tool 6 in the manner of the known RTM method. Alternatively, the matrix material may be applied in an intermediate step to the fiber material 4 applied to the carrier structure 2, or may be provided with the matrix material in a preparatory step which is still to be carried out prior to the method steps shown in FIG.

The invention has been described above with reference to preferred embodiments, variants, alternatives and modifications and illustrated in the figures. These descriptions and illustrations are purely schematic and do not limit the scope of the claims, but are merely illustrative of them. It is understood that the invention can be embodied and modified in many ways without departing from the scope of the claims.

For example, the representation in FIG. 1 can be understood to mean that the fiber material 4 is applied to the corrugated tube 3 forming the carrier structure 2 with a length corresponding to a component length. However, it is equally conceivable and preferred, the fiber material 4 on a corrugated tube 3 of any length Apply and then cut the arrangement to a desired length. This can also be done in a continuous process, wherein, for example, fiber material 4 is continuously braided on a quasi-endless corrugated hose 3 and cut from the braided corrugated pipe 3 pieces of desired length.

It is further preferred that the corrugated tube 3 is held axially during the Beflechendes or Verlegens with the fiber material so that the corrugated tube 3 does not lengthen in this process step.

Although in the figures, the support structure 2 is shown as consisting entirely of the corrugated tube 3, it is also readily conceivable that only one end portion has a corrugated tube-like structure. This end portion can then be pulled out in the direction Z analogously to the representation in FIG. 2 and form a free end 5. A central portion, which does not necessarily have to be in the form of a corrugated tube, can also have any three-dimensional shape and does not have to be continuously cylindrical, as shown in the figures.

In the figures, the corrugated tube 3 is shown with a wave-shaped pointed wave. It should be understood that this illustration is purely schematic and does not limit the inventive concept in any way. The profile of the shaft 3 a can also be rounded and, with particular preference, can also be designed in such a way that in the compressed state of the corrugated tube 3 a flat or almost flat outer surface results, while the shaft 3 a extends or bulges inward like a bead or bellows. Also, the shaft 3, instead of a continuous helix a

Be plurality of individual annular waves, which are formed in the outer surface of the corrugated tube or in a portion of the support structure 2.

While only one axial end of the arrangement according to the invention is shown in FIG. 3, it is to be understood that, at the other axial end (not shown in detail in the figure), the corrugated hose 3 is provided by suitable means such as a plug, a weld, a lid or the like or corresponding shape features of the forming tool 6 may also be completed gas-tight. As far as a radial gap between the fiber material 4 and the support structure 2 is shown in the figures, this serves primarily to illustrate and clarify the illustration. In practice, the support structure 2 may be densely covered with the fiber material 4.

It is understood that the skilled person can make various modifications, variations and developments on the basis of the drawings illustrated and described above, without departing from the scope of the invention defined by the appended claims.

LIST OF REFERENCE NUMBERS

1 preform

2 support structure

3 corrugated tube

3a wave

4 fiber material

5 free end

6 shaping tool

6a interior

7 upper part (partial form)

7a shaping surface

8 lower part (partial form)

8a shaping surface

9 pressure connection part

9a pressure connection line (bore)

9b area

9c receiving structure (annular groove)

10 sealants

11 pressure connection

L longitudinal axis

P overpressure

Z pulling direction

The above list of reference numbers and abbreviations is an integral part of the description.

Claims

claims

1. A method for producing a fiber composite hollow component, in particular for vehicle construction, with the steps:

a) providing an inflatable support structure (2);

b) applying fiber material (4) to the support structure (2) to produce a preform (1);

c) introducing the preform (1) on the support structure (2) in a

Shaping tool (6);

d) generating an overpressure (P) within the support structure (2) such that the preform (1) is pressed by the support structure (2) on shaping surfaces (7a, 8a) of the forming tool (6);

characterized in that

the carrier structure (2) at least in sections has a corrugated hose (3) or a corrugated hose-like element.

2. The method according to claim 1, characterized in that during the execution of step b) the support structure (2) is held so that an axial change in length of the support structure (2) is prevented.

3. The method according to claim 1 or 2, further characterized by the

Step:

b-1) cutting the support structure (2) with the applied fiber material (4) after step b) and before step c) to a length which at least substantially corresponds to a length of the fiber composite hollow component to be produced.

4. The method according to any one of the preceding claims, further characterized by the step:

b-2) stretching the support structure (2) after step b) and before step c) before introduction into the forming tool (6) such that a fiber material (4) free end (5) of the support structure (2) generates becomes.

5. The method according to any one of the preceding claims, characterized in that in the step c) a fiber-free end (5) of the support structure (2) in a pressure connection part (9) of the

Shaping tool (6) is taken pressure-tight.

6. The method according to any one of the preceding claims, characterized

in that the overpressure (P) is introduced into the interior of the carrier structure (2) via a free end (5) of the carrier structure (2) of fiber material (4).

7. The method according to any one of the preceding claims, characterized

characterized in that the applied to the support structure (2)

Fiber material (4) before step b) is provided with a matrix material.

8. The method according to any one of the preceding claims, characterized

characterized in that the preform with a

Matrix material is provided.

9. The method according to any one of the preceding claims, characterized

characterized in that a matrix material is injected via the forming tool (6).

10. forming tool (6) for producing a fiber composite hollow component from a preform (1) having an on an inflatable support structure (2) applied fiber material (4), wherein the forming tool (6) for receiving the preform (1) on the Carrier structure (2) and introducing positive pressure (P) into the interior of the support structure (2) such that the fiber material (4) of the preform (1) under the action of the overpressure (P) by the support structure (2) on shaping surfaces (7a , 8a) of the

Shaping tool (6) is pressed, designed and set up, characterized in that the forming tool (6) has a pressure connection part (9) with a pressure connection (1) for introducing the overpressure (P), wherein the pressure connection part (9) one to a Interior (6 a) of the forming tool (6) facing out Receiving structure (9c), in particular annular groove, which is designed to receive an axial end (5) of the support structure (2), wherein preferably sealing means (10) for pressure-tight sealing of the receiving structure (9a) with the axial end (5) received therein the support structure (2) are provided, and wherein a pressure connection line (9a) is provided which the interior (6a) of the forming tool (6) with the

Pressure supply connection (1) connects and in one of the

Receiving structure (9c) enclosed surface (9b) ends.