Method for producing a fiber-reinforced plastic composite

Abstract

Method for producing a fiber-reinforced plastic composite comprising the following steps: a) at least one fiber semi-finished product (20) is provided and clamped into a rotatable receiving device (16), b) a matrix-forming material is applied to the fiber semi-finished product (20), c) the fiber semi-finished product (20) is rotated during the application process of the matrix-forming material and / or after the application process by means of the receiving device (16), wherein the fiber semi-finished product (20) is an embroidery, and wherein the receiving device (16) is a gripper that grips the fiber semi-finished product (20) in an edge area, or a clamping frame in which the fiber semi-finished product (20) is clamped.

Description

[0001] The invention relates to a method for producing a fiber-reinforced plastic composite, in particular a carbon fiber component.

[0002] Fiber-reinforced plastic components are typically manufactured today using a wet pressing process. In this process, a fiber preform is placed on an application table. A resin is then applied to the preform, forming a matrix. For manufacturing, the resin-impregnated preform is placed in a press. The shape of the fiber-reinforced plastic component is set, and the resin is simultaneously forced into the preform, ensuring uniform infiltration.

[0003] The fiber semi-finished products used are typically non-woven fabrics with a closed surface, resulting in a low-permeability surface. Because of this surface, the resin applied to the fiber semi-finished product cannot flow through it by gravity alone.

[0004] It is also known in the prior art to use knitted fabrics as fiber semi-finished products instead of non-woven fabrics, which can also be load-path optimized. Load-path optimized knitted fabrics are characterized by their adaptation to the subsequent shape of the fiber-reinforced plastic component, particularly to the loads that will occur. The individual fibers of the knitted fabric are laid down differently, resulting in locally varying permeability within the fiber semi-finished product. This can, among other things, lead to the formation of areas within the fiber semi-finished product where few or no fibers are present.

[0005] A disadvantage of using knitted fabrics as fiber semi-finished products has been found to be that the conventional application technique, in which the resin is applied to the fiber semi-finished product lying on the application table, can cause the resin to seep through the gaps or holes in the knitted fabric. The application table and other components used in production are consequently contaminated or soiled with the resin, which is undesirable.

[0006] Furthermore, this results in higher costs in the production of the fiber-reinforced plastic composite component, as the resin flowing through the fiber semi-finished product can no longer be used.

[0007] From DE 905 315 B a process for the production of synthetic resin-impregnated sheets, fleeces or mats using a rotating screen drum is known.

[0008] In DE 4 441 838 C1 a method for impregnating fibrous carrier materials in the form of nonwovens, mats and fabrics using a hollow drum is shown.

[0009] DE 102012 021 786 A1 discloses a rotational impregnation process for manufacturing a component from a fiber composite material.

[0010] A filament winding method using a mandrel is known from WO 2014 039 482 A1.

[0011] The object of the invention is to provide a method for producing a fiber-reinforced plastic composite that is cost-effective and efficient.

[0012] The problem is solved according to the invention by a method according to claim 1.

[0013] In the process for manufacturing a fiber-reinforced plastic composite, in particular a carbon fiber component, at least one fiber preform is provided and clamped into a rotatable holding device. A matrix-forming material is then applied to the fiber preform. The fiber preform is rotated by the holding device during and / or after the application of the matrix-forming material. The fiber preform is a knitted fabric. Furthermore, the holding device is either a gripper that grasps the fiber preform at an edge or a clamping frame in which the fiber preform is clamped.

[0014] The rotating fixture is part of the manufacturing system used to produce the fiber-reinforced plastic component, particularly for infiltrating the fiber preform. The rotating fixture ensures that the fiber preform can be rotated during and / or after the application process.

[0015] The basic idea of ​​the invention is to apply the matrix-forming material to the fiber semi-finished product in such a way that no matrix-forming material drips from or runs through the fiber semi-finished product. Due to gravity, the matrix-forming material applied to the fiber semi-finished product flows in a predetermined direction. Since the fiber semi-finished product is rotated during or after the application process, the flow direction of the viscous matrix-forming material can be specifically controlled to prevent dripping. Furthermore, the rotation of the fiber semi-finished product ensures that the matrix-forming material is distributed homogeneously within it. In general, the fiber semi-finished product is thus infiltrated by the matrix-forming material, while simultaneously ensuring that the matrix-forming material does not drip off. As a result, the production plant is not contaminated or soiled.

[0016] The matrix-forming material typically has a relatively high viscosity, which is why it has a lower flow rate compared to water.

[0017] The twisting or rotation of the fiber semi-finished product during or after application can be seen as analogous to turning a spoon that has previously been dipped in honey. In this analogy, the honey corresponds to the matrix-forming material, while the spoon represents the fiber semi-finished product.

[0018] The fiber semi-finished product rotates, in particular, around an axis of rotation perpendicular to the direction of gravity.

[0019] One aspect stipulates that the fiber semi-finished product is rotated at least 180° during and / or after the application process, ideally multiple times in different directions. This 180° rotation ensures that the flow direction of the matrix-forming material reverses precisely in the final positions due to gravity relative to the fiber semi-finished product. The matrix-forming material does not accumulate on either the top or bottom surface of the fiber semi-finished product.

[0020] In particular, the fiber preform is rotated at least 360° during and / or after the application process. A rotation of at least 360° means that the fiber preform can be rotated once or more than once around its axis. A rotation of 720°, for example, corresponds to two rotations of the fiber preform. The rotation of at least 360° ensures that the matrix-forming material is distributed substantially uniformly over all surfaces of the fiber preform, especially the surfaces of the side edges. With alternating rotations of 180°, the same side edge is always positioned at the lowest point of the fiber preform after it has been rotated 90°, and the matrix-forming material flows towards this point. The matrix-forming material never flows towards the opposite side edge, however, as this side edge is always at its highest point when the fiber preform is rotated 90°.

[0021] According to another aspect, at least one fiber preform rotates under a nozzle that applies the matrix-forming material to the fiber preform. The matrix-forming material can be atomized onto the fiber preform via the nozzle, thus ensuring a uniform and homogeneous coating of the fiber preform.

[0022] In particular, the nozzle is moved linearly during the application process. This linear movement ensures that the fiber semi-finished product can be fully impregnated with the matrix-forming material, even if the nozzle's spray cross-section does not cover the entire surface of the fiber semi-finished product.

[0023] Another aspect includes a collection basin over which the fiber semi-finished product rotates. This basin serves two purposes: firstly, to catch any matrix-forming material that might drip from the fiber semi-finished product, and secondly, to increase operational reliability in the event of an unexpected malfunction in the production line. In the worst-case scenario, the fiber semi-finished product, now coated with the matrix-forming material, could be actively discharged into the collection basin. The collection basin can be filled with water.

[0024] Furthermore, several fiber semi-finished products can be provided, arranged side by side and processed simultaneously. This optimizes the process for manufacturing fiber-reinforced plastic components, as multiple fiber semi-finished products are efficiently wetted and infiltrated with the matrix-forming material at the same time.

[0025] According to another aspect, the fiber semi-finished product is a load-path-oriented knit. This load-path-oriented knit ensures that the finished fiber-reinforced plastic component can withstand the loads that will occur later.

[0026] In particular, the matrix-forming material is a resin. The resin can preferably be an epoxy resin used to form the matrix of the fiber-reinforced plastic composite component. Generally, unsaturated polyester resins (UP resins) or epoxy resins (EP resins), especially polyurethane, can be used.

[0027] Further advantages and features of the invention will become apparent from the following description and the figure to which reference is made.

[0028] The figure shows a manufacturing plant 10 with which a fiber-reinforced plastic composite component can be produced, in particular a fiber semi-finished product can be impregnated and infiltrated.

[0029] The manufacturing unit 10 comprises a nozzle 12 that ejects matrix-forming material in an atomizing manner. The matrix-forming material can be a resin, in particular an epoxy resin.

[0030] The manufacturing plant 10 also includes a receiving unit 14, which has a rotating receiving device 16, designed as a gripper in the illustrated embodiment. The receiving unit 14 also has an actuator that actuates the receiving device 16 and a control unit that controls the actuator, but these are not shown.

[0031] Furthermore, the production plant 10 includes a water-filled collection basin 18, which is essentially located below the nozzle 12.

[0032] The receiving unit 14, in particular the receiving device 16, can hold a fiber semi-finished product 20, as shown in the figure. The fiber semi-finished product 20 can be a load-path-optimized knitted fabric.

[0033] The rotating holding device 16 is arranged such that the fiber semi-finished product 20 is positioned below the nozzle 12 and above the collection basin 18. The fiber semi-finished product 20 is firmly clamped in the holding device 16, thus ensuring that the fiber semi-finished product 20 cannot fall out of the holding device 16.

[0034] The fiber semi-finished product 20 is held in the receiving device 16 such that, in the position shown, it is oriented with a top side 22 towards the nozzle 12 and with a bottom side 24 towards the collection basin 18.

[0035] To produce the fiber-reinforced plastic component, the provided fiber semi-finished product 20 is coated with a matrix-forming material, which is ejected via the nozzle 12. According to the illustrated embodiment, the matrix-forming material ejected from the nozzle 12 first strikes the top surface 22 of the fiber semi-finished product 20.

[0036] Since the fiber semi-finished product 20 may be a load-path-optimized fabric which has corresponding gaps or holes, the matrix-forming material applied via the nozzle 12 would, due to gravity, eventually run through the fiber semi-finished product 20 and emerge on the underside 24 and drip off from it.

[0037] To prevent this, the holding device 16 is designed to rotate, so that the fiber semi-finished product 20, which is held in the rotating holding device 16, rotates with the holding device 16 about its longitudinal axis L. The longitudinal axis L is perpendicular to the direction of the force of gravity.

[0038] The fiber semi-finished product 20 is, for example, rotated by 180° by the rotating receiving device 16, so that the in Fig.The underside 24 shown in Figure 1 is opposite the nozzle 12. This ensures that the matrix-forming material applied to the fiber semi-finished product 20 does not flow through the fiber semi-finished product 20, but rather runs along its surface. This 180° rotation is performed several times in different directions to reverse the flow direction of the matrix-forming material relative to the fiber semi-finished product 20. In the position shown, the matrix-forming material flows from the top surface 22 to the underside 24, whereas in the position rotated by 180°, the matrix-forming material flows from the underside 24, which is associated with the nozzle 12, to the top surface 22.

[0039] The rotating receiving device 16 can also be rotated by more than 360°, ensuring that the matrix-forming material applied to the fiber semi-finished product 20 is evenly distributed on the surfaces, in particular the side edges of the fiber semi-finished product 20.

[0040] Furthermore, the nozzle 12 is designed to be linearly movable in at least one direction, so that the nozzle 12 can be moved linearly with respect to the held fiber semi-finished product 20. This ensures that the entire surface of the fiber semi-finished product 20 can be impregnated with the matrix-forming material. This is particularly advantageous when the nozzle has a spray cross-section that is smaller than the surface area of ​​the fiber semi-finished product 20.

[0041] The nozzle 12 can also be linearly movable in two directions, so that the nozzle 12 can cover the entire surface of the fiber semi-finished product 20.

[0042] If a malfunction occurs in the production plant 10, the control system of the receiving device 14 can be configured to control the receiving device 16 in such a way that the fiber semi-finished product 20 is released. The fiber semi-finished product 20 would then fall into the water-filled collection basin 18. The collection basin 18 ensures that the matrix-forming material does not contaminate any parts or components of the production plant 10. Furthermore, the collection basin 18 can collect matrix-forming material that drips from the fiber semi-finished product 20 despite its rotation.

[0043] In general, several fiber semi-finished products 20 can be held simultaneously by the rotating holding device 16, allowing several fiber semi-finished products 20 to be impregnated and infiltrated in a single process step. This makes the manufacturing process for multiple fiber-reinforced plastic components more efficient.

Claims

[1] Method for producing a fiber-reinforced plastic composite comprising the following steps: a) at least one fiber semi-finished product (20) is provided and clamped into a rotatable receiving device (16), b) a matrix-forming material is applied to the fiber semi-finished product (20), c) the fiber semi-finished product (20) is rotated during the application process of the matrix-forming material and / or after the application process by means of the receiving device (16), wherein the fiber semi-finished product (20) is an embroidery, and wherein the receiving device (16) is a gripper that grips the fiber semi-finished product (20) in an edge area, or a clamping frame in which the fiber semi-finished product (20) is clamped. [2] Method according to claim 1, characterized by that the fiber semi-finished product (20) is rotated at least 180° during the application process and / or after the application process, in particular several times in different directions of rotation. [3] Method according to claim 1 or 2, characterized by , that the fiber semi-finished product (20) is rotated by at least 360° during and / or after the application process. [4] Method according to any one of the preceding claims, characterized by , that at least one fiber semi-finished product (20) rotates under a nozzle (12) which applies the matrix-forming material to the fiber semi-finished product (20). [5] Method according to claim 4, characterized by , that the nozzle (12) is moved linearly during the application process. [6] Method according to any one of the preceding claims, characterized by , that a collection basin (18) is provided over which the fiber semi-finished product (20) rotates. [7] Method according to any one of the preceding claims, characterized by , that several fiber semi-finished products (20) are provided which are arranged next to each other and are processed simultaneously. [8] Method according to any one of the preceding claims, characterized by, that the fiber semi-finished product (20) is a load-path-oriented knit. [9] Method according to any one of the preceding claims, characterized by that the matrix-forming material is a resin.

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