Extrusion process for manufacturing a component and component manufactured by an extrusion process

Abstract

Extrusion process (100) for the production of a component (18), wherein the extrusion process (100) comprises the insertion (103) of a plurality of layers (10) into a tool (15) and the pressing (104) of the plurality of layers (10) by means of the tool (15), where at least one first layer (11) has an additive, wherein the additive is electrically conductive, such that electromagnetic compatibility of the component (18) is achieved by means of the at least one first layer (11), characterized by the fact that the additive comprises a large number of electrically conductive, non-connected elements, wherein the elements are particles having a size of 1 nm to 100 µm, preferably 1 µm to 5 µm, and / or fibers having a diameter of at least 1 nm, preferably at least 5 µm, particularly preferably at least 30 µm, and / or at most 100 µm, preferably at most 60 µm, a maximum length of 0.1 mm to 100 mm, preferably 0.5 mm to 50 mm, most preferably 20 mm to 30 mm, and / or flakes having a plate-like shape and a thickness of 0.1 µm to 1 µm, preferably 0.4 µm to 0.6 µm, preferably the flakes having a width and a length of 5 µm to 20 µm each, preferably 12 µm to 17.5 µm, on, where the additive is not formed as a grid or a film, wherein the flow pressing process (100) includes setting (101) a predetermined damping value with regard to the electromagnetic compatibility to be produced, the damping value is set by selecting a suitable proportion of the additive in the first layer (11).

Description

[0001] The invention relates to a flow forming process for producing a component according to the preamble of claim 1 and to a component produced by a flow forming process according to the preamble of claim 8.

[0002] With the increasing use of electric vehicles and alternative materials, such as plastics, electromagnetic compatibility (EMC) is a problem for which there is currently no established solution. Metallic materials are electrically conductive and therefore inherently offer EMC protection. For non-conductive materials, additional EMC protection must be provided.

[0003] DE 10 059 801 A1 describes, for example, a flow-forming process for manufacturing a fiber composite structure. This structure is produced from a blank that can be consolidated by heat during flow forming. The blank consists of at least one flowable fiber layer impregnated with the matrix system and restructured during the flow forming process. The blank is multi-layered, comprising at least one outer layer with a low fiber content and a structural layer with a comparatively high fiber content. No EMC protection is provided.

[0004] DE 10 149 645 C1 discloses a process for producing electrically conductive polymer composites with electromagnetic shielding function.

[0005] DE 10 2015 209 571 A1 concerns components made of fiber-reinforced plastic composites, such as those that can be used for lightweight components.

[0006] DE 10 2011 088 932 A1 discloses a composite body comprising a plastic matrix in which a first group and a second group of reinforcing fibers are arranged.

[0007] EP 3 131 097 A1 relates to a composite material comprising a composite substrate with a polymer matrix including a fiber entanglement.

[0008] DE 10 059 801 A1 discloses a method for producing a fiber composite structure by means of extrusion.

[0009] In principle, it is possible to apply a metallic coating to plastic components (so-called plastic metallization) or to apply a metallic mesh to the component. The latter is used, for example, in aircraft construction. However, these solutions require an additional process step to apply the EMC shielding layer. For this reason, they are associated with significantly higher costs and longer production times.

[0010] The invention is based on the objective of improving a compression molding process for manufacturing a component in such a way that the EMC protection of the component can be produced cost-effectively and with reduced manufacturing times.

[0011] The aforementioned problem is solved by an extrusion process for manufacturing a component, hereinafter referred to as the process, which involves inserting a multitude of layers into a tool and pressing the multitude of layers using the tool. At least one first layer contains an additive, wherein the additive is electrically conductive, such that electromagnetic compatibility of the component is achieved by means of this first layer.

[0012] A component is considered electromagnetically compatible, in particular, if it has an attenuation value of at least 40 dB, preferably at least 50 dB, and most preferably at least 60 dB, over frequencies from 0.15 MHz to 120 MHz. Advantageously, the component has an attenuation value, particularly a frequency-dependent one, which lies above the straight line defined by the following formula at every frequency between 0.15 MHz and 120 MHz: Attenuation value(frequency)=70dB−30dB*log(frequency / 0.1MHz) / log(120MHz / 0.1MHz)

[0013] The tool comprises, in particular, two tool halves, especially an upper tool half and a lower tool half, which can be heated. The tool is specifically a press tool. The layers are introduced into the open tool onto the lower tool half. In particular, they are placed on a surface of the lower tool half that faces an upper tool half. The layers are stacked on top of each other in a direction perpendicular to the surface of the lower tool half. This direction is preferably referred to as the first direction and is also the closing direction of the tool. In the closed state, the tool can form a cavity that corresponds, in particular, to the shape of the component to be manufactured.

[0014] The term "extrusion process" refers primarily to a process that uses pressure and heat to liquefy the material from which the individual layers are formed, thus completely filling the mold cavity. This is how the component is manufactured. The process encompasses both the manufacturing of the component and ensuring its electromagnetic compatibility. Extrusion is specifically a co-compression process. It is not an injection molding process, where a flowable material is introduced into the cavity after the mold is closed, nor is it a continuous forming process.

[0015] The term "pressing" refers specifically to the application of pressure in a primary direction. In particular, the numerous layers form a stack in a primary direction, the height of which is greater than the extent of the mold cavity in the same direction. By fully closing the mold, pressure in a primary direction is thus applied to the stack of layers.

[0016] The additive is, in particular, carbon. The additive is, in particular, metallic in form. Specifically, the additive can be present in a proportion of 5 wt.% to 70 wt.%, and more preferably 10 wt.% to 50 wt.%, with respect to the first layer. The metal is, in particular, steel, aluminum, or nickel.

[0017] The additive comprises a plurality of electrically conductive, non-connected elements. In particular, it consists of these. According to the invention, the additive is not a grid or a film. The elements are preferably metallic. It is not necessary for all elements to be made of the same material.

[0018] According to the invention, the elements are particles having a size of 1 nm to 100 µm, preferably 1 µm to 5 µm. They are also fibers having a diameter of at least 1 nm, preferably at least 5 µm, particularly preferably at least 30 µm, and / or at most 100 µm, preferably at most 60 µm. Furthermore, the fibers have a maximum length of 0.1 mm to 100 mm, preferably 0.5 mm to 50 mm, most preferably 20 mm to 30 mm. Finally, they are flakes that are plate-shaped and have a thickness of 0.1 µm to 1 µm, preferably 0.4 µm to 0.6 µm. Furthermore, the flakes have a width and length of 5 µm to 20 µm, preferably 12 µm to 17.5 µm.

[0019] The layers are primarily sheet molding compound semi-finished products. This means they are fiber-reinforced composite semi-finished products. These preferably have a sheet-like, dough-like, thermosetting resin matrix. The manufactured component is, in particular, a fiber-reinforced plastic composite. The layers contain a glass fiber content of preferably 5 wt.% to 60 wt.%, and more preferably 15 wt.% to 40 wt.%.

[0020] The electrically conductive additive, comprising at least one first layer, ensures that the manufactured component exhibits electromagnetic compatibility. In other words, the first layer is functionalized with an electrically conductive additive.

[0021] Preferably, the plurality of layers comprises only one, namely the first layer, which includes an electrically conductive additive. The other layers preferably do not contain an electrically conductive additive.

[0022] Alternatively, several layers are provided, e.g., a first layer and a second layer, each containing an electrically conductive additive, while the remaining layers do not contain an electrically conductive additive. In particular, at least 25%, more preferably at least 40%, and / or at most 80%, most preferably at most 60% of the layers are equipped with an electrically conductive additive, while the remaining layers do not contain an electrically conductive additive. Preferably, half of the layers contain an electrically conductive additive, while the other half do not. Preferably, the at least one first layer is an outer layer of the component to be manufactured.

[0023] In particular, the numerous layers are introduced into a central area of ​​the tool. Preferably, the layers are placed on a central area of ​​the surface of the lower tool half.

[0024] The dimensions of the bottom layer, which comes into direct contact with the lower half of the tool during the insertion of the multiple layers, perpendicular to the first direction, can be selected such that the bottom layer covers at least 25%, more preferably at least 40%, and / or at most 95%, more preferably at most 85%, of the surface of the lower half of the tool. A coverage of 50% is most preferred. In particular, the dimensions of the layers perpendicular to the first direction are selected to be identical. In other words, the layers are cut to the same dimensions. The aforementioned coverage level has the advantage of creating shorter flow paths for the material of the layers. This reduces the probability of the materials mixing with each other during the flow process.

[0025] The present method ensures that the component is manufactured from a multitude of layers, with the component and its electromagnetic compatibility being produced in a single step. In other words, the component's electromagnetic compatibility is achieved simultaneously with its production. Therefore, no further process step is required after the component's manufacture to subsequently establish electromagnetic compatibility, for example, by applying a corresponding layer.

[0026] In particular, the process further includes preheating the tool to promote the liquefaction of the layered material. Specifically, the tool is heated to the process temperature, which is specified by the material manufacturer and is necessary for the curing reaction of the thermosetting hard matrix, especially a thermosetting resin.

[0027] In particular, the method comprises closing the tool, wherein this closing occurs particularly at a speed of 0.1 mm / s to 20 mm / s, more specifically 0.1 mm / s to 2 mm / s, as soon as the upper tool half comes into contact with a layer of the plurality of layers. The layer with which the upper tool half comes into contact is preferably an outer layer of the stack formed by the plurality of layers. Preferably, this can be the first layer.

[0028] In particular, the extrusion process involves the flow of the layers within an expansion flow. The term "expansion flow" refers specifically to the fact that the material of the individual layers liquefies due to both the pressure of the pressing process and the application of heat, moving primarily in a plane perpendicular to the first direction, i.e., parallel to the surface of the lower mold half. Expansion flow is dominant and determines the flow behavior. In other words, the flow direction is perpendicular to the first direction. This ensures that the material of the different stacked layers does not mix. This is further supported by the fact that the layers are introduced centrally into the mold, resulting in shorter flow paths and thus reducing the risk of mixing material from different layers.Through the flow process, the layers bond together without mixing.

[0029] In particular, after flowing, the layers, or rather the material of the layers, fill the entire cavity of the tool, followed by a hardening process that can take from a few seconds to a few minutes. In this way, a component with a shape defined by the shape of the cavity is produced, while simultaneously ensuring EMC protection.

[0030] The compression molding process further comprises setting a predetermined attenuation value with respect to electromagnetic compatibility, wherein the attenuation value is set by selecting a suitable proportion of the additive in the at least one first layer. Additionally, the material of the additive can be selected. In particular, the attenuation value is selected such that it is at least 40 dB, preferably at least 50 dB, and most preferably at least 60 dB over frequencies from 0.15 MHz to 120 MHz. Advantageously, the attenuation value, which is particularly frequency-dependent, is selected such that it lies above the straight line defined by the following formula at every frequency between 0.15 MHz and 120 MHz: Attenuation value(frequency)=70dB−30dB*log(frequency / 0.1MHz) / log(120MHz / 0.1MHz)

[0031] In a further aspect, the invention relates to a component manufactured by an extrusion process as described above. The extrusion process comprises inserting a plurality of layers into a die and pressing the plurality of layers using the die, wherein at least one first layer comprises an electrically conductive additive, such that electromagnetic compatibility of the component is achieved by means of the at least one first layer. In particular, the extrusion process for manufacturing the component comprises the steps described in more detail above.The additive comprises a plurality of electrically conductive, non-connected elements, wherein the elements are particles having a size of 1 nm to 100 µm, preferably 1 µm to 5 µm, and / or fibers having a diameter of at least 1 nm, preferably at least 5 µm, particularly preferably at least 30 µm, and / or at most 100 µm, preferably at most 60 µm, a maximum length of 0.1 mm to 100 mm, preferably 0.5 mm to 50 mm, most preferably 20 mm to 30 mm, and / or flakes having a plate-like form and a thickness of 0.1 µm to 1 µm, preferably 0.4 µm to 0.6 µm. Preferably, the flakes have a width and length of 5 µm to 20 µm, more preferably 12 µm to 17.5 µm. The additive is not formed as a grid or a film.A predetermined attenuation value is set with regard to the electromagnetic compatibility to be achieved by selecting a suitable proportion of the additive in the first layer (11). Brief description of the drawings

[0032] The invention is explained in more detail with reference to the following purely schematic figures.

[0033] The figures show: Fig. 1 a process scheme of a flow pressing process according to the invention; Fig. 2 a sectional view of a multitude of layers after being placed in a tool; Fig. 3: a cross-sectional view of the multitude of layers according to Fig. 2 in the not fully closed tool; and Fig. 4: a cross-sectional view of the multitude of layers according to Fig. 3 at a later date. Embodiments of the invention

[0034] Fig. Figure 1 shows a process diagram of a flow pressing process 100 according to the invention.

[0035] The extrusion process 100 comprises the insertion 103 of a plurality of layers 10 into a tool 15. At least one first layer 11 comprises an electrically conductive additive. Thus, the process 100 can be used both to manufacture 108 a component 18 and to establish or ensure its electromagnetic compatibility 109. In particular, the process 100 comprises the simultaneous manufacture 108 of the component 18 and the establishment 109 of its electromagnetic compatibility. The process 100 comprises pressing 104 the plurality of layers 10 using the tool 15.

[0036] Furthermore, the method 100 can include setting 101 a predetermined damping value with regard to the electromagnetic compatibility of the component 18. For this purpose, in particular a suitable proportion of the additive in the first layer 11 can be selected 102.

[0037] Furthermore, the method 100 comprises the prior heating 105 of the tool 15, wherein the heat energy introduced into the layers 10 in this way ensures that the viscosity of the material of the layers 10 decreases during the pressing process. The tool is heated to the process temperature, which is specified in particular by the manufacturer of the material and is required for the curing reaction of the thermoset hard matrix, in particular a thermoset resin.

[0038] Furthermore, the method preferably comprises closing 106 of the tool 15 after the layers 10 have been inserted 103. During the closing 106 of the tool 15, the layers 10 are pressed. The tool 15 is closed, in particular, at a closing speed of 0.1 mm / s to 20 mm / s as soon as an upper tool half 15a comes into contact with a layer 10 of the plurality of layers 10.

[0039] As a result of the heat application and the pressing process, the layers 10 flow under expansion. Subsequently, the material of the layers 10 hardens. In this way, the component 18 is manufactured, ensuring its electromagnetic compatibility.

[0040] Fig. Figure 2 shows a sectional view of a plurality of layers 10 after being placed into a tool 15, which has an upper tool half 15a and a lower tool half 15b. The lower tool half 15b has a surface 15c that bounds the cavity 16 and is oriented towards the upper tool half 15a. The layers 10 are stacked on top of each other in a first direction 19, which is oriented perpendicular to the surface 15c of the lower tool half 15b. The height of the resulting stack of layers in the first direction 19 is greater than the corresponding extent of the cavity 16 in the same direction.

[0041] Both the first layer 11 and the second layer 12 contain a metallic additive that serves to ensure electromagnetic compatibility of the component 18 to be manufactured. The first layer 11 is arranged adjacent to the second layer 12, with the first layer 11 forming the outermost layer 14 of the stack formed by the layers 10. Furthermore, the plurality of layers 10 includes additional layers 13 that do not contain an electrically conductive additive. The plurality of layers 10 is placed in the tool 15 such that it covers 50% of the surface 15c of the lower tool half 15b.

[0042] In Fig. Figure 3 is a cross-sectional view of the multitude of layers 10 of the Fig. 2 shown in the almost closed tool 15. By closing the tool 15 and the fact that the height of the stack in the first direction 19 is greater than the extent of the cavity 16 in the same direction, the multitude of layers 10 is pressed.

[0043] As a result of the pressing process 104, the layers 10 flow within the framework of an expansion flow. This means that the layers flow mainly in a straight line in a plane that is perpendicular to the first direction 19, starting from a central area of ​​the tool 15 towards the outer area. The plane is schematically represented by the second direction 20. Furthermore, the flow direction 17 is shown in Fig. Figure 3 is shown as an example. Once the tool is completely closed, no further flow occurs.

[0044] Fig. Figure 4 shows a cross-sectional view of the multitude of layers 10 of the Fig. 3 at a later time, whereby the cavity 16 is completely filled by the flowing 107 of the layers 10. After the hardening of the layers 10, which have bonded together through the flow process, a component 18 is produced 108, whereby the electromagnetic compatibility of the component is simultaneously established 109. Reference symbol list 100 Flow Pressing Processes 101 Setting a predetermined attenuation value with regard to electromagnetic compatibility 102 Selection of a suitable proportion of the additive in the first layer 105 Preheating the tool 103 Introducing multiple layers into a tool 104 pressing of the multitude of layers using the tool 106 Closing the tool 107 Flow of layers within the framework of an extensional flow 108 Manufacturing a component 109 Establishing electromagnetic compatibility of the component 10 positions 11 first layer 12 second layer 13 more locations 14 outer position 15 tools 15a upper tool half 15b lower tool half 15c surface 16 Cavity 17 Flow direction 18 components 19 first direction 20 second direction

Claims

A compression molding process (100) for manufacturing a component (18), wherein the compression molding process (100) comprises inserting (103) a plurality of layers (10) into a tool (15) and pressing (104) the plurality of layers (10) by means of the tool (15), wherein at least one first layer (11) comprises an additive, wherein the additive is electrically conductive, such that electromagnetic compatibility of the component (18) is achieved by means of the at least one first layer (11), characterized in that the additive comprises a plurality of electrically conductive, non-contiguous elements, wherein the elements are particles having a size of 1 nm to 100 µm, preferably 1 µm to 5 µm, and / or fibers having a diameter of at least 1 nm, preferably at least 5 µm, particularly preferably at least 30 µm, and / or at most 100 µm, preferably at most 60 µm, a maximum length of 0.1 mm to 100 mm,preferably 0.5 mm to 50 mm, most preferably 20 mm to 30 mm, and / or flakes formed in a plate-like shape and having a thickness of 0.1 µm to 1 µm, preferably 0.4 µm to 0.6 µm, preferably the flakes having a width and a length of 5 µm to 20 µm, preferably 12 µm to 17.5 µm, wherein the additive is not formed as a grid or a film, wherein the extrusion process (100) comprises adjusting (101) a predetermined attenuation value with respect to the electromagnetic compatibility to be achieved, wherein the attenuation value is adjusted by selecting a suitable proportion of the additive in the first layer (11). Flow pressing process (100) according to claim 1, characterized in that the additive is metallic. Extrusion process (100) according to one of the preceding claims, characterized in that the additive is present in a proportion of 5 wt.% to 50 wt.% with respect to the first layer (11). Extrusion process (100) according to one of the preceding claims, characterized in that the layers (10) are sheet molding compound semi-finished products. Flow pressing process (100) according to one of the preceding claims, characterized in that the flow pressing process (100) comprises producing (108) the component (18) from the plurality of layers (10), wherein the component (18) and the electromagnetic compatibility of the component (18) are produced in a common step. Extrusion process (100) according to one of the preceding claims, characterized in that the extrusion process (100) comprises closing the tool (15) with a closing speed of 0.1 mm / s to 20 mm / s as soon as an upper tool half (15a) of the tool (15) comes into contact with a layer (10) of the plurality of layers (10). Flow pressing process (100) according to one of the preceding claims, characterized in that the flow pressing process (100) comprises the flowing (107) of the layers within the framework of an expansion flow. Component (18) manufactured by an extrusion process (100) according to any one of claims 1 to 7, wherein the extrusion process (100) comprises the insertion (103) of a plurality of layers (10) into a tool (15) and the pressing (104) of the plurality of layers (10) by means of the tool (15), characterized in that at least one first layer (11) comprises an additive, wherein the additive is electrically conductive, such that electromagnetic compatibility of the component (18) is achieved by means of the at least one first layer (11), the additive comprises a plurality of electrically conductive, non-contiguous elements, wherein the elements are particles having a size of 1 nm to 100 µm, preferably 1 µm to 5 µm, and / or fibers having a diameter of at least 1 nm, preferably at least 5 µm. particularly preferably at least 30 µm, and / or at most 100 µm, preferably at most 60 µm,a maximum length of 0.1 mm to 100 mm, preferably 0.5 mm to 50 mm, most preferably 20 mm to 30 mm, and / or flakes that are plate-shaped and have a thickness of 0.1 µm to 1 µm, preferably 0.4 µm to 0.6 µm, preferably the flakes having a width and a length of 5 µm to 20 µm, preferably 12 µm to 17.5 µm, wherein the additive is not formed as a grid or a film, wherein a predetermined attenuation value with respect to the electromagnetic compatibility to be achieved is set by selecting a suitable proportion of the additive in the first layer (11).

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