PREFORMED MULTILAYER COVERING MATERIAL

Abstract

The invention relates to a multilayer covering material for covering a structural component cavity in a mold for the manufacture of fiber-reinforced composite structural components, comprising a layer containing a gas-permeable but matrix-material-impermeable membrane and a gas- and matrix-material-impermeable foil, which delimits an absorption gap for the evacuation of gas reaching the absorption gap from the structural component cavity through the membrane, and a flow aid layer located between the membrane and the foil in the absorption gap. The covering material is in the form of a pre-formed multilayer material part. The absorption gap of the covering material is sealed at its circumferential edges by a matrix-material-tight joint between the membrane and the foil.

Description

[0001] The present invention relates to a multi-layered covering agent according to the preamble of claim 1.

[0002] From the document DE 10 2017 130 201 A1 it is known to produce the component space in a tool for manufacturing a fiber composite component with a generic covering agent, wherein the individual layers of the covering agent are placed one after the other onto the open tool.

[0003] From German patent application DE 10 2019 115 447 A1, it is known to use a multi-part tool whose parts circumferentially delimit a mold cavity. The tool has vent openings through which gas located in the mold cavity and in the injected matrix material is extracted.

[0004] A generic covering material is known from German patent application DE 20 2015 004 313 U1. Assembly is conventionally carried out by sequentially building up the individual layers in the tool.

[0005] Sealing the vents against the escape of matrix material is a challenge. It is difficult to align the multiple layers within a mold in such a way that gas present in the component cavity can also be vented through the vent. The film must be opened at a suitable point and sealed towards the vent. If the seal is not perfect, the vent can become clogged, resulting in an imperfectly manufactured fiber composite component that must be scrapped. If matrix material enters the vent, it becomes blocked, and no gas can be extracted from the mold cavity.

[0006] Another problem is that the vent opening can only extract gas from the matrix material in the area immediately surrounding it. Extraction over a larger area is not possible with this tool. While it is possible to cover the component cavity successively with multiple layers of the masking material in the usual way, this method involves considerable manual effort and material consumption.

[0007] The object of the present invention is to provide a solution for easily sealing the vent openings of multi-part tools for manufacturing fiber composite components against the ingress of matrix material. Furthermore, a solution is to be found for extending the suction effect of the vent opening across its surface.

[0008] The problem is solved for a generic covering agent by the characterizing features of claim 1.

[0009] The problem is solved for a generic method by using a sealing agent according to one of claims 1 to 8 to seal against penetrating matrix material.

[0010] The covering material, designed as a pre-cut flap, can be applied as a single unit to the inside of the mold wall in the area of ​​the vent opening, along with the attachment element. The membrane seals the extraction chamber within the covering material against liquid matrix material introduced into the component cavity. The film seals the extraction chamber on the side opposite the membrane, creating a gas-tight and matrix-material-tight seal against the matrix material.

[0011] Instead of a film, a membrane that is at least matrix-material-tight could also be used there; however, a film is more economical without incurring any technical disadvantages. Since, in normal applications, the film's outer surface rests against the inner surface of the tool wall, little or no matrix material can be present there.

[0012] The membrane and the film, which are bonded together at least at their edges with a matrix-material-tight seal, define an extraction chamber sealed against the matrix material. Gas can be extracted from the component cavity through the membrane. To prevent the film from lying flat against the membrane, which would cause the extraction chamber to collapse and prevent gas flow, a flow aid is inserted into the extraction chamber. This flow aid consists, for example, of a fibrous material such as a nonwoven or knitted fabric that allows gas to flow through it and that maintains a distance between the membrane and the film, even under the influence of a vacuum applied to the tool.

[0013] The masking material has an opening in the film through which gas drawn into the extraction chamber can escape from the masking material towards the vent. The membrane in the masking material thus keeps matrix material away from the vent, while gas extracted from the component chamber can flow freely from the extraction chamber through the opening into the vent, allowing gas extraction from the component chamber to function through the masking material.

[0014] The sealing element, which is an integral part of the sealing element, seals the sealing material against the inside of the mold wall. The sealing element is placed on the inside of the mold wall with its side facing away from the sealing material, positioned so that gas drawn from the component cavity into the sealing material's extraction chamber can flow from the opening into the mold's vent. The sealing element forms a kind of collar and stiffener for the film in the area of ​​the opening. The sealing element can be shaped to fit snugly against the wall of the vent. It can be held in place, for example, by retaining clips, clips, or similar devices.However, it is also possible to hold the covering material in place with the contact surface of the system element by means of a negative pressure in the area of ​​the vent opening or to use other fastening aids, such as adhesives or the like, which provide adhesion between the contact surface and the inside of the tool wall.

[0015] Since the attachment element is connected to the film in a way that is at least matrix-material-tight, the matrix material located in the component cavity and / or within the matrix material itself cannot pass through the transition zone between the film and the attachment element into the vent opening. If the connection is not only matrix-material-tight but also gas-tight, no gas can flow through the connection zone. The vacuum then acts only on the membrane, and gas passes only through the membrane into the extraction chamber and the vent opening. Naturally, the connection between the contact surface of the attachment element and the inside of the mold wall is also designed to be at least matrix-material-tight.

[0016] With the covering material according to the invention, the vent openings of multi-part tools for manufacturing a fiber composite component can be easily sealed against the ingress of matrix material by simply placing the covering material onto the inlet opening from the component cavity side. It is no longer necessary to insert, fasten, and seal individual layers of a covering into the component cavity at the opening of the vent. Because the layers are already bonded and sealed together to form the finished covering material, only the single covering material needs to be applied at the opening of the vent. Subsequent sealing work is eliminated.

[0017] If a sealing device is connected to a vent, it is possible to extract gas from the component cavity across the entire surface of the membrane. Since the surface area of ​​the membrane in a preferred embodiment of the sealing device is larger than the cross-sectional area of ​​the vent, extraction occurs over a larger area than would be the case if the gas were extracted only through the vent.

[0018] The contact surface is coated with an adhesive layer, allowing the masking material to be fixed to the inside of the tool wall that defines the component space. When the contact surface is coated with an adhesive layer, simply pressing the masking material against the inside of the tool wall is sufficient to attach and secure it. The masking material is then firmly fixed in its intended position without requiring any additional steps.

[0019] According to one embodiment of the invention, the adhesive layer is provided with a non-adhesive release liner. The release liner protects the adhesive layer from unwanted adhesion to other objects before its intended use.

[0020] According to one embodiment of the invention, the adhesive layer and the contact surface for producing an at least matrix-material-tight bond are formed on the inside of a mold wall that defines the component space. The shape, size, and surface finish of the contact surface must be designed such that, in the respective application, no matrix material can penetrate through the bonding zone of the bonding element to the mold wall and reach the area of ​​the vent opening. The adhesive used in the adhesive layer is designed so that it is not dissolved by the matrix material during the flooding and curing phases of the matrix material and reliably holds the masking material in its installed position.

[0021] According to one embodiment of the invention, the opening is round, and the fitting element surrounds the opening with a similarly round contact surface. The round shapes match the typically round shapes of the ventilation openings. Minor dimensional differences can be compensated for by generously dimensioning the contact surface of the fitting element, so that one covering material fits ventilation openings of varying sizes.

[0022] According to one embodiment of the invention, the contact surface has a width in the radial direction from the center of the opening that corresponds to at least one quarter of the diameter of the opening. The width of the contact surface makes it possible to apply the covering material to ventilation openings of varying sizes. Furthermore, the width of the contact surface allows it to compensate for localized unevenness and contamination that may be present in the connection area and could potentially lead to leaks in the connection, by means of the larger surrounding contact area.

[0023] According to one embodiment of the invention, the membrane and the film are thermally welded together at their circumferential edges. This welding process is cost-effective, quick, and reliable.

[0024] According to one embodiment of the invention, the contact element is made of butyl rubber with a closed contact surface. The butyl rubber exhibits elastic properties, effectively dampens vibration and impact energy, and offers good resistance to acids and bases. It deforms under pressure, thus optimally adapting to the contours of the area surrounding the vent opening. This allows the contact element to flexibly adapt to the specific shape of the inner surface of a tool wall that defines the component space and to form a secure, sealing seal.

[0025] According to one embodiment of the invention, the size of the flat surface of the covering material exceeds the cross-sectional area of ​​the opening by more than five times. With such a size ratio, a favorable relationship is achieved between the suction effect of the covering material and the discharge of the extracted gas through the vent opening.

[0026] Further features of the invention will become apparent from the claims, the figure, and the accompanying description. All features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the figure description and / or shown in the figure alone, are usable not only in the combinations specified, but also in other combinations or individually, provided this is covered by the scope of the claims.

[0027] The invention will now be explained in more detail with reference to a preferred embodiment and the accompanying drawings.

[0028] The Fig. 1 Figure 1 shows a cross-section through a covering material 2 located in the component chamber 26 of a tool. The covering material 2 has a membrane 4 on one side and a film 6 on the other. The membrane 4 and the film 6 define the extraction chamber 8, through which the gas extracted from the component chamber 26 via the membrane 4 flows towards the opening 14. To prevent the ingress of matrix material into the extraction chamber 8, the membrane 4 and the film 6 are connected to each other in a matrix-material-tight manner at least at the edges 12.

[0029] On the side of the masking material 2 facing away from the component space 26, a contact element 16 is attached to the outside of the film 6 in the area of ​​the opening 14. The contact surface 18 formed on the contact element 16 allows the masking material 2 to be placed on the inside 24 of a tool wall 22 in the area of ​​a vent opening 32. To improve the adhesion of the masking material 2 to the tool wall 22, an adhesive layer 20 can be arranged on the contact surface 18, causing the masking material 2 to adhere to the tool wall 22.

[0030] In the adjacent Fig. 1 The masking material 2 is not yet attached to the tool wall 22. To attach the masking material 2 to the tool wall 22, it must be pressed onto the tool wall in the direction of the two arrows above the contact surface 18. Afterwards, it is at least matrix-material-tight and bonded to the inner surface 24 of the tool wall 22. Fig. 1 It is evident that the diameters of the opening 14 and the vent opening 32 do not exactly match. However, the dimensional differences are compensated for by the width of the contact surface 18, so that a covering material with an opening 14 whose diameter is smaller than the diameter of the vent opening 32 can nevertheless be used to seal such a vent opening.

[0031] In the Fig. 1 In the illustrated embodiment, the tool consists of a first part 28, which delimits the lower part of the component cavity 26, and a second part 30, which covers the component cavity 26 from above. Preferably, the layers of fibers reinforcing the finished component are inserted into the first part 28 before the component cavity 26 is closed and flooded with matrix material, for example, using a vacuum infusion process. When parts 28 and 30 are placed on top of each other, the component cavity 26 is closed. After the tool is closed, the component cavity 26 is evacuated by a vacuum applied to the vent opening 32. For the sake of simplicity, the vacuum pump with its associated hoses, as well as the tank and the supply line for the matrix material, are not shown in the drawing. Fig. 1 depicted.

[0032] Finally, it should be noted that the size of the in Fig. 1The depicted covering agent 2 and its components in relation to the vent opening 32, the tool as a whole, the size ratios of the individual components of the covering agent 2 to each other, as well as the shape, arrangement and dimensioning of the individual components, may deviate from the illustrated embodiment.

[0033] The invention is not limited to the above embodiments.

[0034] The scope of protection is defined by the claims. It presents no difficulty for a person skilled in the art to modify the exemplary embodiments in a manner deemed suitable to adapt them to a specific application. Reference symbol list

[0035] 2 Covering agent 4 Membrane 6 Film 8 Extraction chamber 10 Flow aid 12 Edge 14 Opening 16 Mounting element 18 Mounting surface 20 Adhesive layer 22 Tool wall

Claims

1. Multilayer covering means (2) for covering a component chamber in a die for producing a fibre-reinforced composite component, having one layer of a membrane (4), which is gas-permeable but non-permeable to matrix material, and a film (6), which is non-permeable to gas and matrix material, which membrane and film between them delimit an extraction chamber (8) for evacuating a gas that has passed from the component chamber through the membrane (4) into the extraction chamber (8), and a layer of a flow aid (10), which is arranged in the extraction chamber (8) between the membrane (4) and the film (6), wherein the covering means (2) is designed as a multilayer prefabricated material cloth, the extraction chamber (8) of the covering means (2) is closed at its circumferential edges (12) by an at least matrix-material-tight connection of the membrane (4) to the film (6), the film (6) has an opening (14), which is intended to allow the gas that has flowed into the extraction chamber (8) to escape in a direction away from the component chamber, a contact element (16) is arranged on the side of the film (6) facing away from the extraction chamber (8), which contact element surrounds the opening (14), is connected to the film (6) in an at least matrix-material-tight manner, and has, on its side facing away from the film (6), a contact face (18), with which the covering means (2) can be applied to the inside of a die wall (22) that delimits the component chamber and does not belong to the covering means, characterized in that the contact face (18) is provided with an adhesive layer (20), with which the covering means (2) can be fixed on the inside of the die wall (22) delimiting the component chamber.

2. Covering means (2) according to Claim 1, characterized in that the adhesive layer (20) is provided with an outwardly non-adhesive pull-off film.

3. Covering means (2) according to one of the preceding Claims 1 or 2, characterized in that the adhesive layer (20) and the contact face (18) are designed to produce an at least matrix-material-tight contact on the inside of a die wall (22) delimiting the component chamber.

4. Covering means (2) according to one of the preceding claims, characterized in that the opening (14) is round, and the contact element (16) encloses the opening (14) with a likewise round contact face (18).

5. Covering means (2) according to one of the preceding claims, characterized in that the contact face (18) has a width in the radial direction from the centre of the opening (14) that corresponds to at least a quarter of the diameter of the opening (14).

6. Covering means (2) according to one of the preceding claims, characterized in that the membrane (4) and the film (6) are fused thermally to one another at the circumferential edges (12).

7. Covering means (2) according to one of the preceding claims, characterized in that the contact element (16) is produced from a butyl rubber with a closed contact face (18).

8. Covering means (2) according to one of the preceding claims, characterized in that the size of the flat face of the covering means (2) exceeds the cross-sectional area of the opening (14) by more than five times.

9. Method for sealing a venting opening in a die for producing a fibre-reinforced composite component, characterized in that a covering means according to one of Claims 1 to 8 is used for sealing against the ingress of matrix material.