Method for manufacturing a structural component

Abstract

Method for manufacturing a load-optimized structural component in a predefined reinforcement area (1), comprising the steps: - Providing a basic hollow component (2) with a component wall (3), at least one inner cavity (4) surrounded by the component wall (3) and at least one access opening (5) penetrating the component wall (3) from the outside to the cavity (4), - Introducing a flowable foam material into the cavity via the at least one access opening (5), wherein the foam material is designed to react in an exothermic reaction to form a pressure-stable and / or energy-absorbing solid foam (6), - Distributing the foam material at least within the reinforcement area of ​​the cavity (4), - Foaming the foam material into a solid foam (6) such that the foam (6) completely fills the cavity (4) at least in the reinforcement area of ​​the basic hollow component (2) and makes continuous surface contact with the component wall (3) in the reinforcement area, - Monitoring of a heating of the component wall (3) across the reinforcement area by means of a heat detection device (14), and - Determining a local non-contact of the component wall (3) by the foam (6) by monitoring the heating of the component wall (3).

Description

[0001] The present invention relates to a method for producing a structural component with optimized load in a reinforcement area, in particular a fiber composite structural component.

[0002] In many high-tech areas, such as aircraft or automobile construction, structural components are designed as composite components made of composite materials, since composite components combine advantageous physical properties of the individual composite materials. Composite components have, for example, a foam core which is surrounded by a cover layer to improve load-bearing capacity, in particular mechanical and / or thermal and / or chemical load-bearing capacity or the like. The cover layer can, for example, have a laid fabric or braid made of fibers, such as glass fibers, carbon fibers, aramid fibers or the like, which is impregnated or interspersed with a curable matrix material, such as a resin. In this way, for example, a particularly lightweight structural component with high mechanical strength can be produced.The function of the foam core in such structural components is essentially to reduce component vibrations, in particular through damping due to a somewhat flexible foam structure, and thus of driving noise to increase driving comfort.

[0003] Structural foams, for example, are used to produce such composite components because of their relatively low density and dimensional stability. In many applications, the structural foams are therefore designed as rigid foams with only a low, in particular microscopic, degree of compliance. The structural foam can, for example, be coated with a fabric or braid made of fibers that is impregnated or interspersed with the matrix material, for example using a resin transfer molding process, also known as RTM. According to alternative methods for reducing component vibrations in thin sheet metal, it is known to inject foam material components into the spaces between components, in particular sheets. These methods are used in particular to reduce vibrations in thin sheet metal.Further processes for producing components with foam cores are known from the documents DE 1 604 693 A and DE 1 504 709 A.

[0004] Known processes for manufacturing structural components with foam cores have the disadvantage of requiring very complex processes and therefore incurring very high production costs. Furthermore, these processes can only produce vibration-damping structural components. Structural components with particularly improved energy absorption or compressive strength cannot be produced using these processes.

[0005] It is therefore an object of the present invention to eliminate or at least partially eliminate the disadvantages described above in a method for producing a structural component, in particular a fiber composite structural component. In particular, it is an object of the present invention to provide a method for producing a structural component which ensures the production of a structural component with optimized loads in a reinforcement region in a simple and cost-effective manner and thus improves the energy absorption capacity and / or compressive strength of a fiber composite structural component. Furthermore, it is an object of the present invention to produce a structural component with improved energy absorption capacity and / or compressive strength.

[0006] The above object is achieved by the patent claims. Accordingly, the object is achieved by a method for producing a structural component with optimized load-bearing capacity in a reinforcement region, having the features of claim 1. Further features and details of the invention emerge from the dependent claims, the description, and the drawings.

[0007] According to the invention, this object is achieved by a method for producing a structural component with optimized load-bearing capacity in a predefined reinforcement area. The method comprises the following steps: - Providing a basic hollow component with a component wall, at least one inner cavity surrounded by the component wall and at least one access opening penetrating the component wall from the outside to the cavity, - introducing a flowable foam material into the cavity via the at least one access opening, wherein the foam material is designed to react in an exothermic reaction to form a pressure-stable and / or energy-absorbing, solid foam, - Distributing the foam material at least within the reinforcement area of ​​the cavity, - Foaming the foam material into a solid foam in such a way that the foam completely fills the cavity at least in the reinforcement area of ​​the basic hollow component and is in continuous contact with the component wall in the reinforcement area, - monitoring heating of the component wall over the reinforcement area by means of a heat detection device, and - Determine a local non-contact of the component wall by the foam by monitoring the heating of the component wall.

[0008] The provided basic hollow component can, for example, consist of several individual structures that are joined together to form the basic hollow component. Provision can be made for individual cavities of the individual structures to be combined to form the inner cavity of the basic hollow component during assembly. Alternatively, the basic hollow component can also be formed in one piece. The basic hollow component has at least one access opening, preferably several access openings, that connect the inner cavity to the surroundings of the basic hollow component. The access openings are preferably arranged on one side of the basic hollow component, e.g., a side that is preferably not a visible side and can preferably be arranged facing upwards for introducing the foam material, so that the flowable foam material cannot easily flow out of the access opening.Any further openings through which the flowable and / or the foaming material could escape from the cavity of the basic hollow component are preferably closed or sealed according to the invention. The basic component can, for example, be bowl-shaped, so that when the cavity is filled, one side of the cavity can also be open, which side is at least not delimited by a continuous component wall. When provided, the basic hollow component is preferably fixed in position, so that a position of the at least one access opening is fixed. According to the invention, a position is understood to mean a position and an orientation. The cavity has an actual shape in the reinforcement region which corresponds to a desired shape of the foamed foam material. According to the invention, movement of the basic hollow component can also be provided for better distribution of the flowable foam material.The component wall can, for example, be made of sheet metal, plastic or the like.

[0009] The structural component to be manufactured has a foam core made of a pressure-stable and / or energy-absorbing foam in the reinforcement area, which is surrounded by a component wall. According to the invention, a reinforcement area is understood to be an area of ​​the structural component that is designed to be stress-optimized by the foam. Therefore, according to the invention, only one part of the structural component, namely the reinforcement area, is designed in this way, while another part of the structural component has a different design.

[0010] The flowable foam material is introduced into the cavity of the basic hollow component via at least one access opening; in the case of multiple access openings, this can also be done via several, preferably all, access openings. This improves the even distribution of the foam material within the cavity. The foam material preferably comprises polyurethane (PU) or the like. The foam that can be produced with the foam material preferably has a relatively high hardness and density. The foam material is preferably provided with further ingredients that, for example, improve or increase the pressure stability and / or energy absorption capacity of the foam. Furthermore, the foam material is designed to foam into the foam in an exothermic reaction. This means that the foam material can be foamed by activation with the release of heat.It can further preferably be provided that the foam that can be produced with the foam material is additionally designed to be vibration-damping and / or sound-insulating.

[0011] Since the foam usually has a larger specific volume or a lower specific density than the foam material due to the pores, the reinforcement region of the cavity is preferably not completely filled with the foam material, in particular in order to avoid maximum internal pressure within the cavity and thus excessive pressure loading on the basic hollow component or the component walls of the basic hollow component. Furthermore, excessive filling of the cavity could possibly hinder complete or uniform foaming. Alternatively, it can be provided that before or during foaming, excess foam material can escape or be displaced from the cavity, e.g. through the access opening and / or an opening provided for this purpose. Alternatively, it can be provided according to the invention that the excess foam material escapes or is displaced from the cavity of the reinforcement region into an adjacent part of the cavity.

[0012] When the foam material is foamed into the solid foam, at least the reinforcement area of ​​the cavity is completely filled with the solid foam, so that in the reinforcement area the foam is in full contact with the component wall. In the context of the invention, full contact means that the foam lies against the component wall, with no pores or air pockets larger than the pores of the foam on the component wall being formed. In the reinforcement area, an outer contour of the foam therefore corresponds to an outer contour of the cavity. Pressure exerted on the component wall from the outside can thus be evenly transmitted to or into the foam. The foam consequently provides an abutment for the component wall. In this way, localized overloading of the component wall due to external forces can be avoided.

[0013] Since the foam material foams up in an exothermic reaction and the generated foam contacts the component wall or is pressed against the component wall, heat is transferred from the foam to the component wall. Ideally, this occurs evenly, namely when the foam in the reinforcement area lies flat against the component wall. If the foam is not formed correctly in the reinforcement area and does not contact the component wall at one point or does not contact it correctly, the heat transfer from the foam to the component wall is weaker at this point. The component wall therefore has a lower temperature at this point than at the points in contact with the foam. Such a temperature difference can be detected when monitoring the heating using a heat detection device, such as preferably an infrared camera.Based on the detected temperature difference, structural components with incorrectly formed foam cores can be identified. With appropriate technical effort, even foam defects of just a few square millimeters, such as 100 mm, can be detected. 2 , detectable.

[0014] The inventive method for producing a structural component with optimized load-bearing capacity in a reinforcement area has the advantage over conventional methods that a structural component optimized for load-bearing capacity using a foam can be produced using simple means and at low cost. By monitoring the temperature of the component wall, defective structural components can be easily, reliably, and cost-effectively identified and subsequently sorted out. This is particularly important for safety-relevant structural components in automotive or aircraft construction. Complex X-ray procedures (e.g., CT scanning) for detecting foam defects are not required.

[0015] It is preferred that the basic hollow component is provided such that at least the reinforcement region of the basic hollow component is arranged in a receiving cavity of a closable receiving mold, and the receiving mold is subsequently closed, wherein the receiving cavity has a shape and size that corresponds or at least substantially corresponds to a shape and size of the reinforcement region of the basic hollow component. Preferably, the receiving cavity is designed to precisely accommodate the reinforcement region. The receiving mold can preferably be arranged in a stationary manner and is formed in at least two parts, such that the reinforcement region of the basic hollow component can be received in a form-fitting manner by the receiving mold and can be fixed in position. Preferably, the complete basic hollow component is arranged in a form-fitting manner in the receiving cavity. The closing of the receiving mold can take place, for example, before the liquid foam material is introduced.Alternatively, it can be provided that the foam material is introduced first and then the receiving mold is closed. In this case, it is preferred that the basic hollow component is fixed to the open receiving mold using fixing means before the foam material is introduced. To monitor the heating of the component wall, the produced structural component is preferably removed from the receiving mold or at least the receiving mold is opened. Such an arrangement of the basic hollow component in the receiving mold has the particular advantage that the basic hollow component can be fixed in its correct position easily, using simple means, and with good reproducibility.

[0016] Further preferably, the receiving mold is cooled to dissipate the heat generated during foaming. This is preferably done via a cooling device having at least one cooling channel formed in the receiving mold and through which a cooling fluid flows for cooling. The heat generated during foaming is thus transferred via the component wall to the receiving mold and the cooling fluid. Cooling is particularly advantageous when the component wall is made of a material that has a relatively low thermal load capacity and could be damaged by the heat generated during foaming. Cooling can be a simple way to protect the component wall from excessive thermal stress.

[0017] The receiving cavity is preferably designed in such a way that, when the receiving mold is closed, it positively limits any expansion of the basic hollow component. The receiving cavity is preferably tolerated according to a fit with the basic hollow component. Foaming can increase the internal pressure within the cavity in the reinforcement area. The foam is pressed from the inside against the component wall. This can cause very high tensile stresses to occur in the component wall, which can damage the basic hollow component or the produced structural component: For example, it can deform, break, or tear. By designing the receiving mold in this way, the structure of the basic hollow component or the structural component is subjected to significantly less mechanical stress during foaming in a cost-effective manner, since compressive forces are transferred from the foam via the component wall directly to the receiving mold.The component wall is therefore essentially only subjected to compressive stress, while no or only very low tensile stresses occur in the component wall.

[0018] According to the invention, it is preferred that the entire base hollow component be arranged in the receiving cavity. Furthermore, it can be provided that the reinforcement region extends over the entire or substantially the entire base hollow component. The inclusion of the entire base hollow component has the particular advantage that the base hollow component can be easily fixed in position and is protected from damage during the process.

[0019] According to a preferred embodiment of the invention, a foam material is used that heats up to a temperature at least 20°C higher than the ambient temperature during exothermic foaming. It is particularly preferred that the foam material heats up to approximately between 100°C and 130°C at room temperature during exothermic foaming. Such a foam material is particularly advantageous for basic hollow components made of a particularly temperature-sensitive material in order to avoid excessive thermal stress.

[0020] Preferably, a foam material is used which is designed to independently form an adhesive connection with the component wall. Alternatively or additionally, an adhesive can be applied to the side of the component wall facing the cavity before the foam material is introduced, e.g. by spraying. An adhesive connection between the foam and the component wall has the advantage that relative movements between the foam and the component wall, in particular due to vibrations, can be effectively prevented using simple means. Erosive wear of the foam is thus avoided or at least reduced. A foam material which is designed to independently form an adhesive connection with the component wall has the advantage that an additional joining process, such as gluing, is no longer necessary. This simplifies the manufacturing process and thus reduces manufacturing costs.

[0021] It is preferred that the foam material comprises at least two components that are mixed together for foaming. The foam material preferably comprises two components. Such a foam material is also referred to as a two-component foam material. The two components can be stored separately from one another. The foaming process is initiated by mixing the two components. It is preferred that the foaming process does not take place directly during mixing of the components or immediately after mixing, but rather with a delay to ensure distribution of the foam material within the cavity. Solidification that occurs too early carries the risk that the foam material cannot penetrate into some areas of the reinforcement region of the cavity, since distribution of the foam material can be hindered by the foam that has already formed.With such a foam material made up of several components, the foaming process is easy to control.

[0022] More preferably, the foam material is injected into the cavity via a nozzle during introduction. For this purpose, a mixing nozzle can be used, for example, in which the components are already mixed in the nozzle. Alternatively, an injection nozzle can be used, by means of which the components are injected into the cavity in such a way that the components are mixed with each other after leaving the nozzle. Injection via a nozzle has the advantage of improving the even distribution of the foam material within the cavity and the mixing of the components.

[0023] According to the invention, it can be provided that when monitoring the heating, an ACTUAL heat distribution across the component wall is determined and compared with a TARGET heat distribution, whereby if a deviation threshold is exceeded, the produced fiber composite structural component is rejected. The TARGET heat distribution describes the heat distribution across the component wall when the foam is evenly distributed in the reinforcement area within the cavity and lies flat against the component wall. An ACTUAL heat distribution that has colder areas than the TARGET heat distribution is an indication that the foam is not adhering to the component wall in these areas or that there is a significant mixing error. The greater the deviation, the more faulty the foam formation. Using this type of monitoring, quality control of the manufactured structural components is possible in a simple and cost-effective manner.

[0024] Preferably, a basic hollow component is provided that is designed as a fiber composite structural component, wherein the component wall comprises fibers impregnated with a matrix material. Such basic hollow components exhibit high strength and high load-bearing capacity while being lightweight.

[0025] A structural component that can be produced by a method according to the invention has a component wall, a cavity surrounded by the component wall, and a reinforcement region. The cavity is filled in the reinforcement region with a pressure-stable and / or energy-absorbing, solid foam that makes surface contact with the component wall in the reinforcement region. The structural component has the same advantages as already described above for the method according to the invention for producing a structural component with load-optimized reinforcement region according to the first aspect of the invention. Accordingly, the structural component is particularly pressure-stable and / or has a particularly high energy absorption capacity. Furthermore, the structural component has a low density and can be produced cost-effectively and using simple means.

[0026] The structural component can be manufactured using a method according to the invention. The method is simple and cost-effective. Structural components can also be manufactured economically in large quantities using the method.

[0027] The method according to the invention can be carried out using a device for producing a structural component with optimized load-bearing capacity in a reinforcement region. The device comprises a closable receiving mold with a receiving cavity for positively receiving at least one reinforcement region of a basic hollow component, an introduction unit for introducing flowable foam material into at least one access opening of the basic hollow component, and a heat detection device for monitoring heating of a component wall of the produced structural component. The device is designed to carry out a method according to the invention.

[0028] A device usable for the method according to the invention and a structural component that can be produced by the method according to the invention are explained in more detail below with reference to the drawings. They show schematically: Fig. 1 in a side view a basic hollow component, Fig. 2 shows a sectional view of the basic hollow component Fig. 1, Fig. 3 in a side view a hollow component made of Fig. 1 manufactured structural component, Fig. 4 shows a sectional view of the structural component Fig. 3, and Fig. 5 shows a device used in a side view.

[0029] Elements with the same function and mode of action are listed in the Fig. 1 to 5 are each provided with the same reference numerals.

[0030] In Fig. 1 and Fig. Figure 2 schematically depicts various views of a basic hollow component 2. In this exemplary embodiment, the basic hollow component 2 is hollow-cylindrical in shape and has a component wall 3 surrounding a cavity 4. An access opening 5 for filling with liquid foam material is formed in the component wall 3. The basic hollow component 3 is designed as a fiber composite component. The basic hollow component 2 shown here is merely an example for illustrative purposes. According to the invention, basic hollow components 2 can have almost any desired shape, in particular with curves, edges, rounded portions, or the like.

[0031] In Fig. 3 and Fig. 4 shows a structural component 1 in different views, whereby the structural component 1 consists of the basic hollow component 2 made of Fig. 1 and Fig. 2. The cavity 4 of the basic hollow component 2 is filled with a foam 6. In this example, the access opening 5 is also filled with foam 6. According to the invention, it can also be provided that the access opening 5 is closed with a different material, e.g., a material of the component wall 3. The foam 6 contacts the component wall 3 over a wide area and continuously.

[0032] Fig. Figure 5 shows a schematic side view of a device 10 for producing a structural component 1 with optimized load in a reinforcement area. The device 10 has a receiving mold 11 with an upper part 11a and a lower part 11b, which are connected to one another via a hinge 17, so that the upper part 11a is pivotally held relative to the lower part 11b. A receiving cavity 12 is formed in the receiving mold 11, which corresponds to the shape and size of the basic hollow component 2 made of Fig.1 and is thus designed to receive the basic hollow component 2. In this exemplary embodiment, the receiving cavity 12 is evenly distributed between the upper part 11a and lower part 11b. An introduction unit 13 with a nozzle 16 for introducing the liquid foam material into the cavity 4 of the basic hollow body 2 is arranged on the upper part 11a. A plurality of coolant channels 15 for cooling the receiving mold 11 and thus the component wall 3 of the basic hollow body 2 are arranged in each of the upper part 11a and lower part 11b. A heat detection device 14, e.g. an infrared camera, for monitoring the heating of the component wall 3 is arranged above the receiving mold 11. List of reference symbols 1 structural component 2 Basic hollow component 3 Component wall 4 Cavity 5 Access opening 6 foam 10 Device 11 Recording format 11a Upper part 11b Lower part 12 Recording cavity 13 Feeding unit 14 Heat detection device 15 Coolant channel 16 nozzle 17 Hinge

Claims

[1] Method for producing a structural component (1) which is load-optimised in a predefined reinforcement area, comprising the steps: - Providing a basic hollow component (2) with a component wall (3), at least one inner cavity (4) surrounded by the component wall (3) and at least one access opening (5) penetrating the component wall (3) from the outside to the cavity (4), - introducing a flowable foam material into the cavity via the at least one access opening (5), wherein the foam material is designed to react in an exothermic reaction to form a pressure-stable and / or energy-absorbing, solid foam (6), - Distributing the foam material at least within the reinforcement area of ​​the cavity (4), - foaming the foam material to form a solid foam (6) such that the foam (6) completely fills the cavity (4) at least in the reinforcement area of ​​the basic hollow component (2) and is in continuous contact with the component wall (3) in the reinforcement area, - monitoring a heating of the component wall (3) over the reinforcement area by means of a heat detection device (14), and - Determining a local non-contact of the component wall (3) by the foam (6) by monitoring the heating of the component wall (3). [2] Method according to claim 1, characterized bythat the basic hollow component (2) is provided in such a way that at least the reinforcement region of the basic hollow component (2) is arranged in a receiving cavity (12) of a closable receiving mold (11) and the receiving mold (11) is subsequently closed, wherein the receiving cavity (12) has a shape and size which corresponds or at least substantially corresponds to a shape and size of the reinforcement region of the basic hollow component (2). [3] Method according to claim 2, characterized by that the receiving mold (11) is cooled to dissipate the heat generated during foaming. [4] Method according to claim 2 or 3, characterized by that the entire basic hollow component (2) is arranged in the receiving cavity (12). [5] Method according to at least one of the preceding claims, characterized bythat a foam material is used which heats up to a temperature at least 20 °C higher than the ambient temperature during exothermic foaming. [6] Method according to at least one of the preceding claims, characterized by that a foam material is used which is designed to independently form an adhesive connection with the component wall (3). [7] Method according to at least one of the preceding claims, characterized by that the foam material has at least two components that are mixed together to foam. [8] Method according to at least one of the preceding claims, characterized by that the foam material is injected into the cavity (4) during introduction by means of a nozzle (16). [9] Method according to at least one of the preceding claims, characterized bythat when monitoring the heating, an actual heat distribution over the component wall (3) is determined and compared with a desired heat distribution, wherein if a deviation threshold value is exceeded, the produced fiber composite structural component (1) is sorted out. [10] Method according to at least one of the preceding claims, characterized by that a basic hollow component (2) is provided which is designed as a fiber composite structural component, wherein the component wall (3) has fibers impregnated with a matrix material.

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