Gas guide arrangement and method for vacuum-assisted processing of a semi-finished fiber product

Abstract

Gas guide arrangement (106, 302, 404) for use in a method for the vacuum-assisted processing of a semi-finished fiber product (100, 300, 400) in an evacuable molding space (114), characterized in that the gas guide arrangement (106, 302, 404) is made of a wire mesh in an inherently rigid and dimensionally stable manner and has a frame-like shape with at least one recess for receiving the semi-finished fiber product (100, 300, 400).

Description

[0001] The invention relates to a gas guide arrangement for use in a method for vacuum-assisted processing of a semi-finished fiber product in an evacuable molding chamber. Furthermore, the invention relates to a method for vacuum-assisted processing of a semi-finished fiber product in an evacuable molding chamber.

[0002] From DE 100 13 409 C1, a method is known for producing fiber-reinforced plastic components from dry fiber composite semi-finished products by means of an injection method for injecting matrix material, comprising the steps of: arranging the fiber composite semi-finished product on a tool, wherein a flow aid is arranged on a surface of the semi-finished product, forming a first space by means of a gas-permeable and matrix material-impermeable membrane at least on one side around the semi-finished product, wherein matrix material can be introduced into the first space, forming a second space adjacent to the first space, which is delimited from the environment by means of a gas- and matrix material-impermeable film sealed off from the tool, extracting air from the second space,whereby matrix material is sucked from the storage container into the evacuated first space and the flow aid causes a distribution of the matrix material over the surface of the semi-finished product facing it and a penetration of the same vertically into the semi-finished product.

[0003] From DE 201 02 569 U1, an arrangement is known for producing a component from a fiber-reinforced material by resin impregnation of a fiber semi-finished product, comprising a mold; a vacuum film, by means of which a vacuum space can be produced, in which the fiber semi-finished product can be positioned on the mold, wherein the vacuum space can be subjected to negative pressure and a supply device for liquid resin to the fiber semi-finished product, during which negative pressure application and temperature during resin impregnation can be controlled and / or regulated such that the boiling point curve is not exceeded with respect to the liquid resin.

[0004] From DE 10 2014 111 358 A1, a multi-part vacuum hood is known for covering fiber material during the production of a fiber composite component, wherein the vacuum hood consists of a flexible material or comprises a flexible material and has a plurality of separate vacuum hood segments which, when assembled, form the multi-part vacuum hood for covering the fiber material, wherein the vacuum hood segments are designed for detachable connection to one another in connection regions provided on the vacuum hood segments to form the assembled, multi-part vacuum hood.

[0005] From DE 10 2014 116 848 A1 a method is known for the automated production of a vacuum structure for the production of a fiber composite component, which is produced by curing a matrix material infused into a fiber material using a vacuum structure, wherein a plurality of unfinished material layers are provided for the vacuum structure by a material provision device, wherein the material layers are automatically joined layer by layer by a joining device to form a prefabricated vacuum structure, wherein before, during or after the joining the material layers are cut by a cutting device depending on predetermined geometric data.

[0006] From DE 40 19 744 A1 a method is known for repairing components made of plastic, in particular made of fibre composite materials, in which material is removed from the damaged or defective area in the component to form a depression and the depression is filled with repair material consisting of resin and fibre material, fibre mats, fibre scrims, fibre fabrics or the like being inserted into the depression in the form of cut-outs adapted to the size and shape of the depression, the cut-outs either being impregnated with resin before being inserted or, instead, the depression is only filled with resin afterwards, and the shape and size of the depression to be produced are set to a few standard sizes and for each individual standard size, associated cut-outs are prefabricated and kept ready, each of which fits at least substantially precisely into the depression of the associated shape and size.

[0007] From DE 10 2011 076 463 A1 a repair method is known for a molded part made of a plastic material, in which a repair element made of the plastic material is applied to a damaged area of ​​the molded part and is bonded to it by the action of heat, wherein the heat is generated by means of a passive heating element made of an electrically conductive material by subjecting the heating element to an alternating magnetic field.

[0008] From the document DE 20 2010 001 836 U1 a device is known for producing a fibre composite component by means of vacuum infusion, with an impregnation tool which can be sealed in an airtight manner and which has a fillable interior space into which a fibre material can be inserted and into which a flowable matrix material can be fed via a feed line opening into the interior space, as well as a suction line for producing a negative pressure in the interior space of the impregnation tool, in which the suction line is laid at least partially within the interior space and is at least partially or completely covered with a gas-permeable membrane which blocks the matrix material.

[0009] From the document DE 60 2004 006 155 T2 a vent plate is known for use in the curing of a composite part, wherein the vent plate comprises two distinct, fixed outer layers with a mesh layer inserted therebetween, wherein each of the outer layers is provided with a plurality of holes prior to assembly of the vent plate, wherein the holes are configured and arranged such that when the two outer layers are attached to one another to form the vent plate, a plurality of passageways are formed to allow air and / or volatile components to pass unhindered through the vent plate, wherein the passageways are configured and arranged such that the insertion of the mesh layer in any position or orientation relative to the outer layers does not substantially block all of the passageways.

[0010] Document EP 2 589 485 A1 relates to a method for venting air and volatiles from a composite part being compressed by a flexible vacuum bag. To facilitate the venting of air and volatiles from a component assembly during a high-flow curing cycle, document EP 2 589 485 A1 proposes arranging a sleeve of foraminous material around the part inside the bag and allowing the air and volatiles to pass through the sleeve from the edges of the part. Furthermore, document EP 2 589 485 A1 proposes wrapping the corners of the part with the sleeve by folding the sleeve onto itself or by bending the sleeve into curves at the corners. Furthermore, document EP 2 589 485 A1 proposes reusing the sleeve as a venting device for sequentially processing a plurality of parts.

[0011] The invention is based on the object of structurally and / or functionally improving a gas guide arrangement mentioned above. Furthermore, the invention is based on the object of improving a method mentioned above.

[0012] The problem is solved with a gas guide arrangement having the features of claim 1.

[0013] The semi-finished fiber product can contain organic fibers, such as aramid fibers, carbon fibers, polyester fibers, nylon fibers, polyethylene fibers, Plexiglas fibers, and / or inorganic fibers, such as basalt fibers, boron fibers, glass fibers, ceramic fibers, and silica fibers. The fibers can contain filaments. The filaments can be combined into rovings. The fibers can be woven, knitted, braided, or stitch-bonded. The fibers can be in the form of a textile. The semi-finished fiber product can have one or more layers.

[0014] The semi-finished fiber product can be a dry semi-finished fiber product. The semi-finished fiber product can be infiltrable with a matrix material. The semi-finished fiber product can be flexible. The semi-finished fiber product can be a semi-finished fiber product pre-impregnated with a matrix material. The semi-finished fiber product can be a prepreg. The semi-finished fiber product can be inherently rigid. The semi-finished fiber product can be finished. Finishing can include cutting, assembling, and / or joining, such as gluing, welding, and / or sewing.

[0015] The matrix material can be thermoplastic. The matrix material can include polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSU), polyetherimide (PEI), and / or polytetrafluoroethylene (PTFE). The matrix material can be thermosetting. The matrix material can include epoxy resin (EP), unsaturated polyester resin (UP), vinyl ester resin (VE), phenol-formaldehyde resin (PF), diallyl phthalate resin (DAP), methacrylate resin (MMA), polyurethane (PUR), and / or amino resins, such as melamine resin (MF / MP) or urea resin (UF). The matrix material can include benzoxaines.

[0016] The semi-finished fiber product can be processed to manufacture a fiber composite component. The semi-finished fiber product can be processed to repair a fiber composite component. The fiber composite component can be a vehicle component. The vehicle can be a land vehicle, motor vehicle, aircraft, watercraft, or spacecraft. The fiber composite component can be a large-area component. The fiber composite component can be a fuselage part of an aircraft. The fiber composite component can be a wing part of an aircraft.

[0017] The mold cavity can be formed using an open mold and a cover layer. The mold has a molding surface. The mold can be inherently rigid. The cover layer can be flexible. The cover layer can be gas-tight. The cover layer can be matrix-tight. The cover layer can be tightly connected to the mold. The mold cavity can be evacuated by applying a negative pressure. "Evacuation" can mean "suctioning off." A gas can be, in particular, air and / or a reaction gas. The semi-finished fiber product can be arranged in the mold cavity. The gas guide arrangement can serve to guide the gas flow during evacuation of the mold cavity.

[0018] The gas guide arrangement can have a predetermined shape. The gas guide arrangement can be handled while retaining its predetermined shape. The gas guide arrangement can be dimensionally stable to such an extent that it at least does not deform significantly under the influence of negative pressure-induced forces. The gas guide arrangement can be elastically deformable. The gas guide arrangement can be dimensionally stable to such an extent that it deforms elastically under the influence of negative pressure-induced forces, in particular, and returns to its original shape after the pressure is released.

[0019] The gas guide assembly is made of a fabric. The gas guide assembly is made of a wire. The gas guide assembly may be made of a stranded wire. The gas guide assembly may be made of a metal. The gas guide assembly may be made of iron or steel. The gas guide assembly may be made of stainless steel. The gas guide assembly may be made of a non-ferrous metal, such as copper, brass, bronze, nickel, or titanium. The gas guide assembly may be made of a refined material, for example, rolled, heat-treated, sintered, pickled, electropolished, coated, and / or cleaned.

[0020] The gas guide arrangement can additionally have a layered shape. The gas guide arrangement can have a flat shape. The gas guide arrangement can have a planar shape. The gas guide arrangement can have a singly or multiply curved shape.

[0021] The gas guide arrangement has a frame-like shape. The gas guide arrangement can have at least one edge section. The gas guide arrangement has at least one recess. The at least one recess serves to accommodate a semi-finished fiber product. The at least one recess can have a shape adapted to a semi-finished fiber product to be accommodated. The gas guide arrangement can have a height adapted to a semi-finished fiber product to be accommodated. The at least one recess can be angular. The at least one recess can be polygonal. The at least one recess can be quadrangular, in particular rectangular. The at least one recess can be round. The at least one recess can have a straight contour, at least in sections. The at least one recess can have a curved contour, at least in sections. The at least one recess can have a multiply curved contour, at least in sections.

[0022] The gas guide arrangement can be multi-layered, in particular three-layered. The gas guide arrangement can have several individual layers. The gas guide arrangement can have folded layers.

[0023] Furthermore, the problem underlying the invention is solved by a method having the features of claim 4.

[0024] The method comprises the following steps: first, arranging at least one inherently rigid and dimensionally stable gas guide arrangement, which is made of a wire mesh and has a frame-like shape with at least one recess for receiving a semi-finished fiber product, on a forming surface of a forming tool and subsequently arranging and positioning a semi-finished fiber product in the recess of the gas guide arrangement.

[0025] The method may further comprise at least one of the following steps: arranging the semi-finished fiber product on a molding surface of an open mold and / or on the gas guiding arrangement; arranging the gas guiding arrangement on a molding surface of an open mold and / or on the semi-finished fiber product; covering the semi-finished fiber product and the gas guiding arrangement with a cover layer; tightly connecting the cover layer and the mold to form an evacuable molding space; heating the semi-finished fiber product; evacuating the molding space.

[0026] A layered gas guide arrangement can also be arranged between a molding surface of a molding tool and a semi-finished fiber product. A layered gas guide arrangement can also be arranged between a semi-finished fiber product and a cover layer.

[0027] A frame-shaped gas guide assembly is arranged on a molding surface of a molding tool. A semi-finished fiber product is arranged on a frame-shaped gas guide assembly. The frame-shaped gas guide assembly serves to position a semi-finished fiber product. The gas guide assembly can be reused.

[0028] In the method, a shaped element can be used which is at least partially transparent to thermal radiation, at least in sections. The shaped element can have a low attenuation constant for parts of the infrared spectrum. The shaped element can be at least partially transparent to thermal radiation, at least in a section which serves to create a semi-finished fiber product. The shaped element can have a very low thermal conductivity compared to metal. The shaped element can have a thermal conductivity of approximately 1.3 W / (m·K) to approximately 1.6 W / (m·K), in particular of approximately 1.46 W / (m·K). The shaped element can have a very low heat capacity compared to metal. The shaped element can have a very low coefficient of thermal expansion compared to metal. The shaped element can be made of glass ceramic, at least in sections.

[0029] The mold element can have a plate-like shape. The mold element can have a flat shape. The mold element can have a single or multiple curvature. The mold element can serve as a pressure element. The mold element or pressure element can be used to press a semi-finished fiber product. The mold element or pressure element can serve to press a semi-finished fiber product against a molding tool. The mold element can serve as a molding tool. The mold element can form at least a section of a molding tool.

[0030] The method may further comprise at least one of the following steps: arranging the semi-finished fiber product on a molding element; arranging a gas guiding arrangement on a molding element and / or on the semi-finished fiber product; arranging a molding element or pressure element on the semi-finished fiber product in order to press the semi-finished fiber product; covering the semi-finished fiber product, the gas guiding arrangement and the molding element or pressure element with a cover layer; tightly connecting the cover layer and the molding tool in order to form an evacuable molding space; heating the semi-finished fiber product using thermal radiation; evacuating the molding space.

[0031] The heat radiation can be applied using an infrared radiator. The semi-finished fiber product can be exposed to heat radiation through the mold element or molding tool and / or through the mold element or pressure element.

[0032] The semi-finished fiber product can be arranged in a single layer or in multiple layers. The semi-finished fiber product can be arranged in a stack. The semi-finished fiber product can be arranged directly on the mold element or molding tool. A decoupling layer can be arranged between the mold element or molding tool and the semi-finished fiber product. The cover layer can be arranged directly on the semi-finished fiber product. A decoupling layer can be arranged between the cover layer and the semi-finished fiber product. The cover layer can be at least partially transparent to thermal radiation. The cover layer can be at least partially transparent to thermal radiation, at least in sections. A sealing tape can be used to tightly connect the cover layer and the mold element or molding tool. The evacuable molding chamber can have at least one vacuum connection. The at least one vacuum connection can have a membrane-like cover.The membrane-like cover can be gas-permeable and impermeable to the matrix material. The at least one vacuum connection can be arranged on the cover layer. The at least one vacuum connection can be arranged on the mold. The process can be carried out in an automated or semi-automated manner.

[0033] In summary and in other words, the invention thus provides, among other things, a method for processing plastics by means of vacuum bag processes for producing thermoplastic organic sheets and components as well as for repairing objects made of plastics.

[0034] The gas guide assembly can also be referred to as a breather. A three-layer metallic wire mesh can be used as the gas guide assembly. The wire mesh can be attached only laterally, along one edge, around the laminate. The shape of the laminate can be pre-cut from the wire mesh. The laminate can be precisely inserted into the wire mesh. A vacuum connection can be installed above or below the wire mesh to prevent airflow from being blocked.

[0035] The wire mesh can have a rigid structure. The wire mesh can be used as often as required and does not require regular replacement. The metallic wire mesh can maintain a constant height under negative pressure.

[0036] A printing element that is transparent to heat radiation can be used, for example a glass ceramic plate made of Ceran ® A component can be heated directly.

[0037] Glass ceramics can be used as an upper and lower tool on both sides of the component to be consolidated. The component can be heated from both sides using infrared radiation.

[0038] "May" refers in particular to optional features of the invention. Accordingly, there is always an embodiment of the invention that has the respective feature or features.

[0039] The invention reduces expenditure such as time, cost, energy, and / or material requirements. Requirements for temperature resistance can be reduced. Coating can be omitted. The need for consumables can be reduced. Repair options for fiber composite components are expanded. Process control is simplified. Resource efficiency is increased. Waste volumes are reduced. Reproducibility is increased. Process reliability is increased. Mobile application can be enabled. Flow control during evacuation is improved. Evacuation is made easier. Manual work can be reduced. Complexity is reduced.

[0040] Exemplary embodiments of the invention are described in more detail below with reference to the figures. Further features and advantages will become apparent from this description. Specific features of these exemplary embodiments may represent general features of the invention. Features of these exemplary embodiments combined with other features may also represent individual features of the invention.

[0041] They show schematically and by way of example: Fig. 1 an arrangement for the vacuum-assisted processing of a semi-finished fiber product with a gas guide arrangement made of a wire mesh, a glass ceramic plate as a pressure element and a vacuum connection at the top, Fig. 2 Pressure curves depending on the distance to a vacuum connection, Fig. 3 an arrangement for the vacuum-assisted processing of a semi-finished fiber product with a gas guide arrangement made of a wire mesh, a glass ceramic plate as a pressure element and a vacuum connection at the bottom, Fig. 4 an arrangement for the vacuum-assisted processing of a semi-finished fiber product with a glass ceramic plate as a forming tool, a gas guide arrangement made of a wire mesh and a glass ceramic plate as a pressure element.

[0042] Fig. 1 shows an arrangement for vacuum-assisted processing of a semi-finished fiber product 100. The arrangement comprises an open mold 102 with a molding surface, a pressure element 104, a gas guide arrangement 106, a cover layer 108, and an overhead vacuum connection 110.

[0043] The semi-finished fiber product 100 is a textile fiber-matrix semi-finished product pre-impregnated with reactive resins. A metal plate serves as the molding tool 102. The pressure element 104 is transparent to thermal radiation. The pressure element 104 has a very low thermal conductivity of, for example, approximately 1.46 W / (m K) and virtually no thermal expansion. A glass-ceramic plate serves as the pressure element 104. The gas guide arrangement 106 is made of a wire mesh. The gas guide arrangement 106 has a frame-like shape with a cutout. The cutout of the gas guide arrangement 106 and the semi-finished fiber product 100 have corresponding contours. A flexible, gas-impermeable film serves as the cover layer 108. The vacuum connection 110 is arranged on the cover layer 108 in the region of the gas guide arrangement 106. The vacuum port 110 is provided with a gas-permeable and matrix material-impermeable membrane-like cover.

[0044] To process the semi-finished fiber product 100, the gas guide assembly 106 is first arranged on the molding tool 102. The unconsolidated semi-finished fiber product 100 is then inserted into the recess of the gas guide assembly 106. The gas guide assembly 106 serves as a positioning frame for the semi-finished fiber product 100. The pressure element 104 is then arranged on the semi-finished fiber product 100 in order to press the semi-finished fiber product 100 evenly and subsequently achieve a high-quality component surface. The gas guide assembly 106, the semi-finished fiber product 100, and the pressure element 104 are then covered with the cover layer 108, and the cover layer 108 is tightly connected to the molding tool 102 using a band-shaped seal 112 to define an evacuable molding space 114. The semi-finished fiber product 100 is then heated using thermal radiation. An infrared radiator can be used to heat the semi-finished fiber product 100.The thermal radiation penetrates the cover layer 108 and the pressure element 104 and directly heats the semi-finished fiber product 100. Adjacent areas are thus exposed to only a reduced thermal load. Subsequently, the mold cavity 114 is evacuated. Air and / or reaction gases are extracted via the vacuum connection 110 and the gas guide arrangement 106.

[0045] The gas guide arrangement 106 has a high and consistent gas permeability. Fig. 2 shows pressure curves 202, 204 as a function of a distance to the vacuum connection 110. In the diagram 200 in Fig. 2, a distance to the vacuum port 110 is plotted on an x-axis, and a pressure is plotted on a y-axis. When a glass fabric is used as the gas guide arrangement, a pressure curve 202 results, from which it is clear that a negative pressure applied to the vacuum port rapidly loses effectiveness with increasing distance from the vacuum port. When a gas guide arrangement 106 made of a wire mesh is used, a pressure curve 204 results, from which it is clear that a negative pressure applied to the vacuum port 110 remains effective even with increasing distance from the vacuum port 110.

[0046] During evacuation, the cover layer 108 is pulled toward the forming tool 102 due to negative pressure, whereby the semi-finished fiber product 100 is subjected to a compressive force and consolidated under the influence of pressure and heat. The gas guide arrangement 106, made of a wire mesh, is not compacted, thus ensuring a uniform evacuation flow with increased throughput and reduced flow resistance even during evacuation. The gas guide arrangement 106, made of a wire mesh, can be reused for processing additional semi-finished fiber products.

[0047] In another embodiment, a layered gas guide arrangement made of a wire mesh can additionally be arranged in a layered manner between the forming tool 102 and the semi-finished fiber product 100 and / or between the semi-finished fiber product 100 and the cover layer 108.

[0048] Fig. Figure 3 shows an arrangement for the vacuum-assisted processing of a semi-finished fiber product 300 with a gas guide arrangement 302 made of a wire mesh, a glass ceramic plate as a pressure element 304 and a vacuum connection 306 located below. The vacuum connection 306 is arranged in the region of the gas guide arrangement 302 in the mold 308. Furthermore, particular reference is made to Fig. 1 and Fig. 2 and the corresponding description.

[0049] Fig. 4 shows an arrangement for the vacuum-assisted processing of a semi-finished fiber product 400 with a glass ceramic plate as a forming tool 402, a gas guide arrangement 404 made of a wire mesh and a glass ceramic plate as a pressure element 406.

[0050] The semi-finished fiber product 100 can thus be heated from above by the cover layer 408 and the pressure element 406 and / or from below by the molding tool 402. Furthermore, particular reference is made to Fig. 1 and Fig. 2 and the corresponding description. Reference symbol 100 semi-finished fiber products 102 Form element, forming tool 104 Form element, pressure element 106 Gas routing arrangement 108 top layer 110 Vacuum connection 112 Seal 114 Forming room 200 diagram 202 Pressure curve 204 Pressure curve 300 semi-finished fiber products 302 Gas routing arrangement 304 Form element, pressure element 306 vacuum connection 308 Form element, forming tool 400 semi-finished fiber products 402 Form element, forming tool 404 Gas routing arrangement 406 Form element, pressure element 408 Top layer

Claims

[1] Gas guide arrangement (106, 302, 404) for use in a method for the vacuum-assisted processing of a semi-finished fiber product (100, 300, 400) in an evacuable molding space (114), characterized by that the gas guide arrangement (106, 302, 404) is made of a wire mesh in an inherently rigid and dimensionally stable manner and has a frame-like shape with at least one recess for receiving the semi-finished fiber product (100, 300, 400). [2] Gas guide arrangement (106, 302, 404) according to claim 1, characterized by that the gas guide arrangement additionally (106, 302, 404) has a layer-like shape. [3] Gas guide arrangement (106, 302, 404) according to at least one of the preceding claims, characterized by that the gas guide arrangement (106, 302, 404) is multi-layered, in particular three-layered. [4] Method for the vacuum-assisted processing of a semi-finished fiber product (100, 300, 400) in an evacuable molding space (114), wherein at least one gas guide arrangement (106, 302, 404) according to at least one of the preceding claims is used to evacuate the molding space (114), characterized by that firstly the at least one gas guiding arrangement (106, 302, 404) is arranged on a forming surface of a forming tool (102, 308, 402) and subsequently a semi-finished fibre product (100, 300, 400) is arranged and positioned in the recess of the gas guiding arrangement (106, 302, 404). [5] Method according to claim 4, characterized by that in addition a layer-shaped gas guide arrangement (106, 302, 404) is arranged between a forming surface of a forming tool (102, 308, 402) and a semi-finished fiber product (100, 300, 400) and / or between a semi-finished fiber product (100, 300, 400) and a cover layer (108, 408). [6] Method according to at least one of claims 4 to 5, characterized by that the gas guide arrangement (106, 302, 404) is reused.

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