Method for manufacturing molded parts

Abstract

A method for the production of molded parts, in particular parts made of fiber composite material, is illustrated and described. In order to reduce the load on the membrane, the membrane (4, 4A', 4B') according to the invention can be slid through a seal (16, 16') and in step c) the membrane (4, 4A', 4B') is at least partially resistant to the expansion forces (F A ) can be caused to slide through the seals (16, 16').

Description

[Technical Field]

[0001] The present invention relates to a method for producing molded parts, in particular from fiber composite materials, comprising: a) an apparatus comprising a first press tool, a second press tool, at least one membrane and at least one seal, the first press tool and the second press tool being movable relative to one another between an open position and a closed position, a working space for a workpiece being formed between the first press tool and the second press tool, the membrane being at least partially arranged between the first press tool and the second press tool, the membrane being at least partially arranged in the working space, at least in the closed position at least one cavity for a working medium being formed between the membrane and the first press tool and / or the second press tool, the cavity being at least partially sealed by the seal at least in the closed position, a sealing force being able to be applied to the membrane by means of the seal in order to seal the cavity, the membrane being at least partially arranged in the working space between the first press tool and the second press tool, the working space being at least partially arranged in the working space, the working space being at least partially arranged in the working space between the membrane and the first press tool and / or the second press tool, the working space being at least partially arranged in the working space ... a) providing an apparatus, wherein the cavity and the first and / or second press tool have different coefficients of thermal expansion; b) applying a sealing force to the membrane using a seal, wherein the cavity is at least partially sealed by applying the sealing force to the membrane, wherein the sealing force applies a frictional force between the membrane and the seal; and c) applying pressure and / or temperature to the membrane, preferably using a working medium in the cavity, wherein the membrane expands at least partially in the working space, preferably expanding more strongly than the first and / or second press tool, preferably using a working medium in the cavity to apply pressure to the membrane, wherein the pressure opposes expansion of the membrane into the cavity, thereby generating an expansion force along the membrane surface, wherein the expansion force opposes the frictional force between the membrane and the seal, at least adjacent the seal. [Background technology]

[0002] Fiber composites are composite materials that essentially consist of two main components: reinforcing fibers and a plastic ("matrix" or "resin") in which the fibers are embedded. The combination of the two main components allows the composite as a whole to have better properties than either of the two components alone. For example, due to their high tensile strength in the direction of the fibers, the fibers help to increase the tensile strength of the composite. On the other hand, the matrix ensures, for example, that the fibers are held in place and protected from mechanical and chemical influences.

[0003] One of the options for the production of components from fiber composite materials is based on the use of pre-manufactured fiber-resin semi-finished products (so-called "prepregs", short for "preimpregnated fibers"). In the case of such semi-finished products, the fibers are provided with a resin system that has not yet fully reacted, so that the semi-finished product is still available in a flexible form (e.g., web or roll). The prepregs can only be transformed by completing the chemical reaction when the component is produced and cured under high pressure and temperature. This step can be carried out, for example, in a press.

[0004] For example, prepregs are processed in large quantities in the aircraft industry. A processing challenge is that the aerospace industry often requires very complex part geometries due to reinforcing elements, such as spars. Furthermore, assembly operations should be reduced, which should be achieved by using fewer but larger components. The combination of complex geometries and large component dimensions increases the demands on the equipment and processes for manufacturing these components. One requirement is, for example, that the membrane used in the equipment optimally matches the workpiece geometry so that pressure and / or temperature can be applied uniformly to the workpiece without placing excessive loads on the membrane.

[0005] For example, Patent Document 1 discloses an apparatus and method for manufacturing components from fiber composite materials. According to this, the component to be manufactured is inserted between two shells. Pressure is thereby uniformly applied to the component to be manufactured, whereby a flexible membrane acts on the component, with hydraulic pressure acting on the membrane on the side of the membrane opposite the component. The membrane is thus pressed against the component surface by hydraulic pressure. In this method, it must also be ensured that in the case of curved component surfaces, hydraulic pressure acts on all sides, and therefore the force acting from the membrane on the component surface is the same everywhere, especially the force component acting perpendicular to the component surface.

[0006] The use of such a "membrane press" for producing parts from fiber composite materials is also known from DE 10 200 04 133 A1.

[0007] In these known presses, only one side of the component is provided with a flexible membrane while the other side of the component is provided with a rigid tool, which simplifies the design of this type of press, but this type of press, especially for workpieces that deform during the pressing process, has the disadvantage that it is only possible to adapt the geometry to the workpiece on the side of the flexible membrane.

[0008] Thus, presses in which two membranes are arranged on opposite sides of the workpiece are also known. For example, a press of this type is known from Patent Document 3. The press shown there has two press elements, each of which is fitted with one membrane (see FIGS. 4 and 5). Both membranes are rigidly attached to one of the press elements. While such a fixed attachment of the membranes facilitates sealing of the cavity bounded by the membranes and is easy to implement by design, it has the disadvantage of not being able to optimally adapt the membrane to the workpiece surface. Furthermore, due to the rigid clamping method, it is not possible to compensate for thermally induced expansion of the membrane. This can lead to uneven pressure distribution and reduced component quality, while also subjecting the membrane to high loads, especially high stresses.

[0009] The object underlying the present invention is therefore to design and further develop the method initially mentioned and described in more detail above in such a way that the load on the membrane is reduced. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] German Patent Application Publication No. 10 2017 113 595(A1) [Patent Document 2] U.S. Patent Application Publication No. 2016 / 0297153(A1) [Patent Document 3] International Publication No. 2018 / 167730(A1) Summary of the Invention [Means for solving the problem]

[0011] This object is achieved in a method according to the preamble of claim 1 in that the membrane can be passed by the seal and in step c) the membrane is passed by the seal due to an expansion force.

[0012] The method according to the invention is a method for producing a molded part.

[0013] The method first comprises step a) of providing an apparatus, in particular a press. This type of press is also known as a "membrane press." The apparatus comprises a first, e.g., upper press tool, a second, e.g., lower press tool, and at least one membrane.

[0014] The first and / or second press tool is preferably manufactured from metal, more preferably steel, and especially from Invar. The use of metal, especially steel, allows for a long service life of the press tool. Invar also has a very low coefficient of thermal expansion. Therefore, the use of Invar allows for highly accurate machining or manufacturing of workpieces, especially molded parts, even at fluctuating temperatures during the pressing process.

[0015] The membrane can be formed, for example, by a thin metal plate, preferably a thin steel plate. A membrane made of a thin metal plate, especially a steel plate, has the advantage that, on the one hand, it can transmit high pressure due to the mechanical properties of the metal, and, on the other hand, it is well suited for heating or cooling the workpiece due to the high thermal conductivity of the metal. Therefore, the membrane is advantageously provided for applying pressure and / or temperature to the workpiece. The membrane is preferably formed as one piece, but may alternatively be formed as several pieces. The device may also include two or at least two membranes. Using two or at least two membranes allows pressure and / or temperature to be transmitted to the workpiece, especially the molded part, from separate sides in a simple manner.

[0016] The device also includes at least one seal. The seal may be, for example, a graphite seal, preferably with a wire mesh. The seal may thereby be provided on the first press tool and / or the second press tool. Furthermore, the seal may extend at least partially substantially parallel to the membrane, in particular the membrane surface. The seal is preferably designed as two parts or at least two parts.

[0017] The first and second press tools can be moved relative to each other between an open position and a closed position. This allows the press to be opened and closed. The relative movement between the first and second press tools can preferably be a substantially linear movement, particularly an up-and-down movement, between the open and closed positions. Linear movement, particularly an up-and-down movement, means that adjusting the press tools between the open and closed positions is presumably fast and simple. In the closed position, the first and second press tools move toward each other and preferably at least partially contact each other. In the open position, the first and second press tools move away from each other so that a workpiece can be inserted between the two press tools. In addition to the open and closed positions, the first and second press tools can also preferably be moved to at least one intermediate position relative to each other. The at least one intermediate position is thereby particularly located between the open and closed positions.

[0018] A working space for the workpieces is formed between the first and second press tools, advantageously at least in the closed position of the first and second press tools. The workpieces are, in particular, molded parts, preferably made of a fiber composite material. In the working space, at least one workpiece can be inserted, thereby, preferably between the at least one membrane, the first press tool, and / or the second press tool. Pressure and / or temperature can be advantageously applied to the workpieces in the working space, at least in the closed position, especially by means of the membrane.

[0019] At least one cavity for the working medium is formed between the membrane and the first and / or second press tool, at least in the closed position. The cavity is thereby preferably at least partially delimited by the at least one membrane and the first and / or second press tool. The cavity is intended to accommodate the working medium therein. In other words, the cavity can be filled with the working medium. The membrane and the first and / or second press tool are thus advantageously coupled to each other in a gas- and / or liquid-tight manner. The working medium is, for example, a gas or a liquid. Pressure and / or temperature can also be preferably applied to the working medium. The pressure and / or temperature that can be applied to the working medium can be transmitted to the workpiece, particularly by means of the membrane. The membrane is preferably deformable. The cavity can also be advantageously moved and / or deformed toward the workpiece, preferably adjacent to the membrane, particularly by filling it with the working medium and / or applying pressure and / or temperature. Advantageously, at least one seal is provided at least partially at one end of the cavity, at least in the closed position, and / or at least one end of the cavity is bounded by said at least one seal. Preferably, when two or at least two membranes are provided, a cavity may be provided between the first press tool and the first membrane, and preferably a second cavity may be provided between the second press tool and the second membrane.

[0020] The cavity may be at least partially sealed in at least the closed position by a seal, and a sealing force may be applied to the membrane to seal the cavity using the seal. The sealing force may be generated by, for example, a pressing force applied by the first press tool and / or the second press tool and transmitted to the at least one seal. The sealing force may, for example, alternatively or additionally be generated by the force of the weight of components of the device.

[0021] The membrane and the first and / or second press tool also have different coefficients of thermal expansion. Preferably, the coefficient of thermal expansion of at least one membrane is greater than the respective coefficient of thermal expansion of the first and / or second press tool. The first and / or second press tool are therefore advantageously manufactured from Invar, as this metal has a low coefficient of thermal expansion.

[0022] The method also includes step b) applying a sealing force to the membrane using the seal, whereby the cavity is at least partially sealed by applying the sealing force to the membrane, and the sealing force applies a frictional force between the membrane and the seal. The sealing force presses the seal against the membrane so that the working medium cannot at least partially escape from the cavity. The magnitude of the frictional force often depends, within certain limits, on the magnitude of the sealing force that generates it, and is approximately linearly related (the ratio between the frictional force and the contact pressure is also called the "coefficient of friction"). For example, as the sealing force increases, the frictional force between the membrane and the seal also increases. The frictional force preferably acts along the membrane surface, thus parallel to the membrane surface. Preferably, the frictional force acts in a substantially horizontal or substantially vertical direction. The frictional force opposes movement of the membrane and / or forces acting along the membrane surface adjacent to the seal. The frictional force therefore preferably opposes relative movement between the membrane and the seal. In particular, frictional forces oppose movement of the membrane out of and / or into the working space.

[0023] Frictional forces can be static or sliding friction depending on whether there is relative motion between the seal and membrane. If the seal and membrane are moved relative to each other, there is sliding friction. If the seal and membrane are not moved relative to each other, there is static friction. If a force large enough to exceed the static friction limit is applied to the static friction, there is relative motion between the membrane and seal, and therefore there is sliding friction between the membrane and seal.

[0024] The method also includes step c) of applying pressure and / or temperature to the membrane, preferably using a working medium in the cavity. A further step of applying pressure and / or temperature to the first and / or second press tools, particularly using a working medium in the cavity, may also be specified. To apply pressure and / or temperature to the membrane, the first and / or second press tools using the working medium, the pressure and / or temperature are preferably applied to the working medium itself. Alternatively or additionally, the pressure and / or temperature may be applied to the membrane, the first and / or second press tools by applying pressure and / or temperature to the first and / or second press tools. The pressure and / or temperature may be applied to the workpiece in the working space by applying pressure and / or temperature to the membrane, the first and / or second press tools. The membrane may preferably be at least partially in contact with the workpiece, thereby applying pressure and / or temperature to the workpiece.

[0025] In the present case, "applying a temperature" refers in particular to heating and / or cooling.

[0026] Step c) further includes the membrane expanding at least partially in at least the working space, preferably expanding more than the first and / or second press tool. Due to the expansion of the membrane, the membrane surface expands, particularly in the working space, and / or the membrane elongates. The membrane, the first and / or second press tool preferably thermally expand. Furthermore, the membrane, the first and / or second press tool expand, particularly due to the application of pressure and / or temperature. To achieve the expansion, the application of temperature particularly includes heating. Alternatively or additionally, the membrane, the first and / or second press tool may contract due to the application of pressure and / or temperature. In this case, it may be specified that the membrane contracts more than the first and / or second press tool. To achieve the contraction, the application of temperature particularly includes cooling.

[0027] The method may therefore include a step c1), which preferably involves applying pressure and / or temperature to the membrane, the first press tool, and / or the second press tool by means of a working medium in the cavity, so that the membrane at least partially contracts, in particular thermally contracts, at least in the working space. In particular, it may be provided that the membrane contracts more strongly than the first press tool and / or the second press tool. Step c1) may thereby be performed before and / or after step c). It may therefore be provided that the membrane, the first press tool, and / or the second press tool are cooled before and / or after heating the membrane, the first press tool, and / or the second press tool.

[0028] Step c) also comprises applying pressure to the membrane, preferably by means of a working medium in the cavity. This application of pressure to the membrane may in particular be the application of pressure and / or temperature, as already described, preferably by means of a working medium in the cavity. However, alternatively or additionally, pressure may also be applied to the membrane by means of other means.

[0029] Step c) further includes applying pressure to oppose the expansion of the membrane into the cavity, thereby generating an expansion force along the membrane surface. The pressure is a pressure applied to the membrane. Due to the expansion of the membrane, the membrane surface widens and / or the membrane, particularly the section of the membrane located in the working space, elongates. The expansion, particularly bulging, of the membrane into the cavity would result in the membrane no longer being in substantially continuous contact with the workpiece being machined or manufactured, and therefore pressure and / or temperature that cannot be uniformly applied to the workpiece. Furthermore, the bulging or loosening of the membrane can result in high loads and, therefore, damage to the membrane. To prevent this, sufficient pressure must oppose the expansion, particularly bulging, of the membrane into the cavity. The pressure applied to the membrane is therefore advantageously at least as large, preferably greater, than the pressure applied to the membrane in the direction of the cavity due to the expansion of the membrane.

[0030] In the present case, "along the membrane surface" is preferably understood to mean in the direction of the membrane surface, which is also preferably the membrane surface adjacent to the workpiece to be machined or manufactured, at least in the closed position.

[0031] Expansion, in particular bulging, of the membrane into the cavity is understood in this case to mean in particular expansion of the membrane in the direction of the adjacent cavity, in particular in the direction of the cavity region adjacent to the expanded region of the membrane, e.g., if the membrane is oriented horizontally, expansion into the cavity is expansion with at least one vertical component in the direction of the adjacent cavity.

[0032] The pressure applied to the membrane, which opposes the expansion of the membrane into the cavity, also generates an expansion force along the membrane surface, which thereby preferably acts at least partially, in a direction towards or away from the seal, particularly adjacent the seal.

[0033] The expansion force is preferably generated by the pressure applied to the membrane being at least partially dissipated along the membrane surface. By applying pressure to the membrane, the membrane is at least partially pressed against the workpiece to be machined or manufactured. As a result, the membrane is at least partially clamped between the workpiece to be machined or manufactured and the pressure applied to the membrane. Due to this clamping, the membrane can expand at least partially, preferably substantially, substantially transverse to the clamping direction and therefore only along the membrane surface. This can also generate or at least influence an expansion force along the membrane surface.

[0034] Step c) further includes the expansion force opposing the frictional force between the membrane and the seal at least adjacent to the seal. When the membrane expands, the expansion force acts adjacent to the seal outward from the working space along the membrane surface. In this case, a frictional force opposes movement of the membrane out of the working space and / or a frictional force acts along the membrane surface toward the working space. When the membrane contracts, a frictional force opposes movement of the membrane into the working space and / or a frictional force acts along the membrane surface away from the working space. The expansion force also preferably opposes the frictional force between the membrane and the seal at the contact area between the seal and the membrane.

[0035] During step c), the membrane comes into at least partial contact with the workpiece to be machined or manufactured, in particular due to the application of pressure and / or temperature.

[0036] According to the present invention, it is provided that the membrane can be forced through the seal, and in step c), the membrane is forced at least partially through the seal due to an expansion force. By allowing the membrane to pass through the seal, uniform contact of the membrane with the workpiece to be machined or manufactured can be ensured without excessive load being imposed on the membrane. In the case of membrane expansion, the membrane surface can be expanded and / or the membrane surface or section can be guided out of the working space. Sagging or bulging of the membrane, which would cause stress on the membrane, is thus avoided. As a result, the membrane can be in substantially continuous contact with the workpiece to be machined or manufactured. In the case of membrane contraction, the membrane's ability to pass through the seal in turn allows the membrane surface or section to enter the working space, especially in the area where the membrane surface is reduced and / or the membrane is shortened. The membrane can therefore be in substantially continuous contact with the workpiece being machined or manufactured without being exposed to excessive loads, in particular tensile stresses.

[0037] By forcing at least a portion of the membrane through the seal due to the expansion force, the load on the membrane can also be reduced. For passage of the seal through the membrane, particularly in the case of membrane expansion, the expansion force can be used to dispense with pretensioning the membrane, or at least to reduce the pretension applied to the membrane. However, it is not necessary for the membrane to be forced through the seal by the expansion force alone. For passage of the seal through the membrane, it is therefore preferable that the sum of the forces acting along the membrane surface of the membrane acting adjacent to the seal, which oppose the frictional force between the membrane and the seal, is greater than the frictional force between the membrane and the seal. The sum of the forces acting along the membrane surface of the membrane acting adjacent to the seal, which opposes the frictional force between the membrane and the seal, thereby includes at least the expansion force adjacent to the seal. Preferably, the expansion force adjacent to the seal is also the largest force acting along the membrane surface acting adjacent to the seal, which opposes the frictional force between the membrane and the seal. By passing the membrane through the seal, the membrane is preferably under tension and / or the membrane is in substantially continuous contact with the workpiece being machined or fabricated.

[0038] In this case, the magnitude of each and / or each (several) of the above forces is always considered in relation to each and / or each (several) of the forces.

[0039] The membrane may be movable relative to the first and / or second press tools, particularly due to expansion forces against the first and / or second press tools. There may also be friction between the membrane and the first and / or second press tools and / or other parts of the apparatus. However, the friction between the membrane and the seal is essential for the membrane to pass through the seal, as this is typically the largest frictional force applied to the membrane and opposes passage of the membrane through the seal.

[0040] According to a first configuration of the method, steps b) and c) are provided to overlap at least in time. This ensures that the cavity is sufficiently sealed by the sealing force while the membrane can be forced through the seal. Step b) can in particular begin before step c) and / or end only after step c). This means that leakage of the working medium from the cavity can be particularly reliably avoided.

[0041] A further embodiment of the method assumes that the expansion force is greater than the friction force between the membrane and the seal. This ensures that the membrane passes through the seal. Furthermore, pretensioning of the membrane can be omitted or at least reduced. The expansion force is, in particular, an expansion force adjacent to the seal that opposes the friction force between the membrane and the seal. The expansion force is thereby preferably greater than the friction force between the membrane and the seal at least partially during step b) and / or at least partially during step c), in particular continuously during step b) and / or continuously during step c). This ensures that the membrane passes through the seal.

[0042] In one embodiment, the method includes the following steps, performed after step a) and preferably before step b) and / or step c): a1) preparing at least one workpiece; a2) inserting the workpiece into the apparatus, particularly the working space; and a3) moving the first and / or second press tools to a closed position. The at least one workpiece may have a matrix and fibers inserted into the matrix. The fibers inserted into the matrix may be, for example, carbon fibers, glass fibers, aramid fibers, etc. The fibers may be used as a semi-finished product, for example, in the form of a mat, nonwoven fabric, woven fabric, knitted fabric, or knitted fabric. The matrix or resin may be formed, for example, from a thermoplastic. The workpiece may be a completed "fiber matrix semi-finished product," also known as a "prepreg." To move the first and / or second press tools to the closed position, the press tools are preferably moved toward each other along the press axis. The movement of the first and / or second press tool to the closed position may be, in particular, a substantially linear movement. Preferably, step a1) is performed before step a2) and before step a3). Step a2) is also preferably performed after step a1) and before step a3). It may also be provided that step b) is performed before steps a1), a2) and a3), in particular step b) may be performed at least before step a3). As a result, the cavity may already be sealed and filled with the working medium before the first and second press tools are moved to the closed position.

[0043] According to a further configuration of the method, the device provided in step a) is provided to include at least one device for varying the pretension of the membrane. The device for pretensioning the membrane may be realized, for example, by a spring with an adjustable spring stroke or an adjustable pretension. Alternatively or additionally, the pretension may be realized hydraulically and / or pneumatically by a device for applying pretension to the membrane. The pretension of the membrane may be set and / or varied using this type of device, for example, to adapt the pretension to the workpiece being manufactured or machined. The setting and variability of the pretension allow the membrane to already have a pretension before pressure and / or temperature are applied to the workpiece, in particular before pressure and / or temperature are applied to the working medium disposed in the cavity. Similarly, the device for varying the pretension of the membrane may preferably apply a pretension force to the membrane, thereby contributing to the passage of the seal by the membrane, in particular during step c).

[0044] According to one embodiment, the method is specified to include the following step a4) of applying pretension to the membrane by a device for varying the pretension, which is performed after step a) and preferably before step b) and / or step c). The pretension ensures that the membrane already has a smooth surface at the start of the application to the workpiece and is not subjected to tension solely by the working medium disposed in the cavity, and is therefore "smoothly pulled." This has the advantage that uniform application of the membrane to the workpiece already occurs at the start of the temperature and / or pressure application, and that the membrane is preferably in substantially continuous contact with the membrane. By step a4), which is preferably performed before step b) and / or step c), the membrane can already be pretensioned before pressure and / or temperature are applied to the membrane, in particular before pressure and / or temperature are already applied to the working medium disposed in the cavity. Step a4) can be performed after steps a1), a2), and a3) or, alternatively, at least before step a3), in particular before steps a1), a2), and a3). It is also advantageously provided that step a4) at least overlaps step b) and / or step c). Step a4) may be carried out at least simultaneously with step b) and / or at least step c). Step a4) may in particular start before step b) and / or before step c) and end only after step b) and / or after step c). This ensures in particular that there is sufficient pretension on the membrane while it is being passed through the seal.

[0045] A further embodiment of the method is characterized in that a pretensioning force is applied to the membrane by pretensioning the membrane in step a4), and preferably the pretensioning force is smaller than the friction force between the membrane and the seal, particularly in step b) and / or step c). The pretensioning force acts along the membrane surface and preferably acts against the friction force between the at least one membrane and the at least one seal, particularly when the friction force opposes the movement of the at least one membrane out of the working space. The pretensioning force applied to the membrane by pretensioning in step a4) is preferably also applied to the membrane at least in step b) and / or at least in step c). The pretensioning force can thus contribute to the passage of the seal through the membrane, particularly in step c), so that even a small expansion force is sufficient to force the membrane through the seal. A pretensioning force that opposes the friction force between the membrane and the seal and is smaller than the friction force between the membrane and the seal may reduce the load on the membrane and therefore increase the service life of the membrane. In particular, during step b) and / or step c), the membrane is already highly loaded in these steps due to the application of pressure and / or temperature, so that the pretensioning force opposing the frictional force between the membrane and the seal is preferably smaller than the frictional force between the membrane and the seal. In addition, during step c), the membrane is already in substantially continuous contact with the workpiece to be manufactured or machined due to the application of pressure. The pretensioning force may also be smaller than the frictional force between the membrane and the seal before and / or after step b) and / or step c).

[0046] According to an embodiment of the method, the pretension applied to the membrane during step b) and / or step c) is varied, in particular reduced, by a device for varying the pretension. As a result, the membrane is subjected to high forces, particularly during step b) and / or step c), and the load on the membrane can be kept as low as possible during the method. This allows the pretension to be varied depending on the sealing force. Preferably, the pretension is reduced when the sealing force decreases and / or increased when the sealing force increases. Alternatively or additionally, the pretension may be varied depending on the pressure and / or temperature applied to the membrane. Preferably, the pretension is reduced when the pressure and / or temperature decreases and / or the pretension is increased when the pressure and / or temperature increases. The pretension may also be varied, preferably increased and / or reduced, before and / or after step b) and / or step c).

[0047] A further configuration of the method is characterized in that the sum of the expansion force and the pretensioning force is greater than the friction force between the membrane and the seal, particularly during step b) and / or step c). This allows the membrane to pass through the seal against the friction force. This is preferably an expansion force adjacent to at least one seal as well as a pretensioning force acting along the membrane in the direction of this expansion force. However, the expansion force does not have to cause passage alone and can therefore be smaller. Therefore, it can be advantageously specified that the expansion force adjacent to the seal is smaller than the friction force between the membrane and the seal, which preferably opposes the expansion force. Advantageously, in this case, the pretensioning force is also smaller than the friction force between the membrane and the seal.

[0048] A further embodiment of the method provides that the pressure and / or temperature of the working medium in the cavity is changed during step b) and / or step c). By varying the pressure and / or temperature of the working medium in the cavity, the pressure acting on the membrane and / or workpiece and / or the temperature acting on the membrane and / or workpiece can also be changed. Because both the pressure and the temperature can be varied, it is possible to provide a varying pressure and temperature profile instead of a constant pressure and a constant temperature. For example, an increase in pressure and / or temperature can be first provided, then a constant pressure and / or temperature can be maintained, and finally a decrease in pressure and / or temperature can be provided. For example, a change in the pressure of the working medium can be achieved by changing the amount of working medium disposed in the cavity by inflow or outflow of the working medium. On the other hand, a change in the temperature of the working medium can be achieved by, for example, circulating the working medium and an inflowing working medium having a higher or lower temperature than the working medium disposed in the cavity, thereby heating or cooling the working medium disposed in the cavity.

[0049] According to a further embodiment of the method, the device provided in step a) preferably includes at least one device for varying the sealing force, preferably adjacent to the seal. The frictional force acting on the membrane can also be varied by the device for varying the sealing force. The variable sealing force can be achieved, for example, by an actuator acting on the seal, pressing it more or less firmly against the membrane surface. If two or more seals are provided, each seal is preferably provided with a device for varying the sealing force, so that the sealing force at each seal can be set and varied independently of the other seals. By varying the sealing force upon application of pressure and / or temperature to the membrane, working medium, and / or workpiece, it is possible to adapt the effectiveness of the seal to changing requirements during the method. Therefore, adapting the effectiveness of the seal based on needs is particularly advantageous, since the two objectives of a particularly good seal (high sealing force) and a particularly good membrane mobility, especially good membrane ability to pass through the seal (low sealing force), cannot be achieved simultaneously and to the maximum extent, resulting in a conflict of objectives. One way to resolve such conflicting objectives is to establish a hierarchy between the competing objectives. For example, a good seal may be defined as the primary objective, while good membrane mobility may be defined only as a secondary objective. By varying the sealing force during the process, it is possible to change the hierarchy between competing objectives during the process. For example, at the beginning of the process (e.g., during the heating phase during temperature increase), membrane mobility may be defined as the primary objective, since thermally induced expansion of the membrane is specifically permitted during this phase. This is achieved by establishing a low sealing force, and therefore low friction, between the membrane and the seal. On the other hand, during the further course of the process (e.g., at a constant high temperature and high pressure), good membrane sealing may be defined as the primary objective, while there is a high risk of leakage during this phase, since thermally induced expansion of the membrane is no longer likely to occur as a result of the nearly constant temperature.This can be achieved by setting a higher sealing force, and therefore a higher friction force, between the membrane and the seal. Thus, the tunability or variability of the sealing force allows for situation-based and need-based prioritization of competing objectives.

[0050] One configuration of the method is characterized in that the device provided in step a) includes at least one second membrane, and at least one second cavity for the working medium is formed between the at least second membrane and the first and / or second press tool, at least in the closed position, and a sealing force can be applied to the second membrane using at least one second seal to seal the second cavity, and the second membrane can be passed through the second seal. The use of a second membrane allows for multiple surface actions on the workpiece without bending the membrane. Thus, when two separate membranes are used, the workpiece can be acted on individually, for example, to respond to local deformations of the workpiece. At least one membrane can preferably be bonded to the first press tool, and at least the second membrane can be bonded to the second press tool. The at least one membrane and the at least second membrane can have the same or different thicknesses. In particular during step b) and / or step c), substantially the same pressure and / or substantially the same temperature and / or different pressures and / or different temperatures may also be applied to the at least one membrane, the at least second membrane, the at least one cavity and / or the at least second cavity in each case. Preferably, it is also provided that in step b) a sealing force is applied to the at least second membrane, thereby applying a friction force between the at least second membrane and the at least second seal. Advantageously, it is also provided that in step c), pressure and / or temperature are applied to the at least second membrane, preferably by means of a working medium in the at least second cavity, such that the at least second membrane at least partially expands in at least the working space, preferably more than the first press tool and / or the second press tool, and pressure is applied to the at least second membrane, preferably by means of a working medium in the at least second cavity, such that the pressure opposes the expansion of the at least second membrane into the at least second cavity and thus generates a second expansion force along the membrane surface of the at least second membrane.The second expansion force opposes a frictional force between the at least second membrane and the at least second seal adjacent to the at least second seal. Preferably, in step c), the at least second membrane is also forced at least partially through the at least second seal due to the second expansion force.

[0051] According to one embodiment of the method, the pressure of the working medium disposed in the cavity in step b) and / or step c) is increased to at least 1.2 bar, in particular 2 bar. Preferably, the pressure of the working medium disposed in the cavity in step b) and / or step c) is increased to a maximum pressure in the range between 10 bar and 50 bar, in particular between 15 bar and 30 bar. Increasing the pressure to at least 1.2 bar, in particular 2 bar, ensures that a sufficiently large expansion force is applied, particularly along the membrane surface. However, these initial values ​​depend strongly on the size of the press working space and the membrane thickness and may in some cases be significantly higher, for example, at least 2.5 bar, 4 bar, 5 bar, or even 8 bar. A rule of thumb of 1.0 bar to 2.0 bar per millimeter of initial membrane thickness applies. These values ​​are then used to increase or adjust to the stated working pressure. Optionally, the maximum pressure in step c) may then be increased to a maximum of 70 bar instead of a maximum of 50 bar.

[0052] Alternatively or additionally, it may be provided that in step b) and / or step c) the temperature of the working medium arranged in the cavities is increased to a maximum temperature in the range between 280°C and 500°C, in particular between 310°C and 410°C. Preferably, if there are at least two cavities, the pressure and / or temperature of both cavities are increased accordingly. The above pressures and temperatures have provided optimal results in the production of molded parts from fiber composite materials. The above values ​​are maximum values, and lower pressure and temperature values ​​are also reached during production in the press, for example during the warm-up and cooling phases.

[0053] Finally, a further embodiment of the method is characterized in that the method comprises the following step c) of opening the apparatus and removing the workpiece, which is performed after step b) and / or after step c). To open the apparatus, the first press tool and / or the second press tool are moved relative to each other to an open position. In the open position, there is sufficient space between the press tools to allow easy and quick removal of the workpiece.

[0054] The invention is explained in more detail below on the basis of the drawings which show only preferred embodiment examples. [Brief explanation of the drawings]

[0055] [Figure 1A] 1 shows a first configuration of an apparatus for carrying out the method according to the invention in a cross-sectional view in an open position with no workpiece inserted; [Figure 1B] 1B is the apparatus from FIG. 1A in the open position with a workpiece inserted. [Figure 1C] 1B is the apparatus from FIG. 1A in a closed position with a workpiece inserted. [Figure 2] 1C is a close-up view of a portion of the device from FIG. 1C. [Figure 3] A close-up view of a portion of the device from Figure 1C. [Figure 4A] 2 shows a second configuration of the device for carrying out the method according to the invention in a cross-sectional view in an open position with no workpiece inserted; [Figure 4B] The apparatus from FIG. 4A in the open position with a workpiece inserted. [Figure 4C] The device from FIG. 4A in the closed position with a workpiece inserted. [Figure 5] A close-up view of the device from Figure 4C.

[0056] FIG. 1A shows a first configuration of an apparatus 1 for carrying out the method according to the present invention in a cross-sectional view in an open position with no workpiece inserted. The apparatus 1 includes a first upper press tool 2 and a second lower press tool 3. The two press tools 2, 3 can be moved relative to each other, for example, vertically (as indicated by the arrows in FIG. 1A). The two press tools 2, 3 can thereby be moved relative to each other between an open position and a closed position. Furthermore, the press includes a membrane 4 disposed at least partially between the first press tool 2 and the second press tool 3. In this case, the membrane 4 is attached to the first press tool 2. As an alternative to the configuration shown in FIG. 1, the membrane 4 can also be attached to the second press tool 3. A cavity 5 for a working medium, e.g., oil, is formed between the membrane 4 and the first press tool 2. The membrane 4 is made of metal and preferably has a thickness ranging between 0.2 mm and 3.5 mm. The cavity 5 can be filled with a working medium through a channel 6. In both the upper press tool 2 and the lower press tool 3 holes 7 are provided through which a heating and / or cooling medium can be led.

[0057] In the configuration of the apparatus 1 shown in Figure 1A, a working space 8 is formed between the first press tool 2 and the second press tool 3, into which a workpiece (not shown in Figure 1A) can be inserted. In this configuration, the working space 8 includes, in particular, a recess 8a in the second press tool 3. The two press tools 2, 3 have guides 9 which can be formed, for example, by a protrusion 9A and a recess 9B, where the protrusion 9A may be provided on the second press tool 3 and the recess 9B may be provided on the first press tool 2.

[0058] The membrane 4 is connected to the first press tool 2 in the following way: the first press tool 2 has a peripheral edge element 10 which is screwed to the first press tool 2 (the screw connection is not shown in FIG. 1A ). Between the first press tool 2 and its edge element 10 a gap 11 is formed, through which the membrane 4 is guided. The gap 11 opens into a hollow space 12 in which a clamping device 13 is provided, in which the membrane 4 is clamped. The clamping device 13 is connected to a tension anchor 14 which is guided out of the first press tool 2 and the edge element 10 through the opening, where it is pressed outwards by a spring 15 bearing it on its outer surface, thereby applying a pretension to the membrane 4, in particular a pretension force F V A seal 16 is provided in the gap 11 to allow movement of the membrane 4 to seal the cavity 5. The membrane 4 can thus be forced through the seal 16. A device 17 for varying the sealing force is provided adjacent to the seal 16. A device 18 for varying the pretension is also provided adjacent to the spring 15.

[0059] Figure 1B shows the apparatus 1 from Figure 1A in the open position with a workpiece 19 inserted. The areas of the apparatus 1 already described are also provided in Figure 1B with the corresponding reference numbers. The difference from the position shown in Figure 1A is that the workpiece 19 has been inserted into the working space 8, in particular into the recess 8A of the second press tool 3.

[0060] FIG. 1C shows the apparatus 1 from FIG. 1A in the closed position. The previously described areas of the apparatus 1 are also shown in FIG. 1C with the corresponding reference numbers. The apparatus 1 is closed by moving the two press tools 2, 3 toward each other in the closed position. In the position shown in FIG. 1C, pressure and / or heat are applied to the workpiece 19. Pressure is applied by a working medium, e.g., oil, guided through the channel 6 into the cavity 5, thereby pressing the membrane 4 toward the workpiece 19. Heat can be applied in various ways. One possibility is to heat the working medium guided through the channel 6 into the cavity 5 so that heat is transferred from the working medium disposed in the cavity 5 through the membrane 4 to the workpiece 19. Conversely, the working medium can be cooled to cool the workpiece 19. Alternatively or additionally, it may be provided that a heating and / or cooling medium is passed through the hole 7, thereby first heating or cooling the two press tools 2, 3, and then the membrane 4 and the workpiece 19. In the same way, pressure and / or temperature may be applied to the membrane 4, the first press tool 2 and / or the second press tool 3. As a result of the pressure action, the workpiece 19 is compressed in the position shown in Figure 1C.

[0061] Figure 2 shows in an enlarged view some areas of the device 1 from Figure 1C. Areas of the device 1 already described are also shown in Figure 2 with corresponding reference numbers. The clamping and sealing of the membrane 4 is particularly visible in Figure 2A. The cavity 5 applies a sealing force F to the membrane 4. D Preferably, a sealing force F D The seal is at least partially formed by a seal 16 pressing against the membrane 4 with a sealing force F D acts perpendicular to the surface of the membrane 4, i.e., in a direction approximately perpendicular in FIG. 2A. D The magnitude of the sealing force F can be varied by the device 17 for varying the sealing force. This can be done, for example, by the device 17 for varying the sealing force comprising an actuator which presses the seal 16 with an increased or decreased force against the membrane 4. DA larger sealing force F results in a more reliable seal but limits the mobility of the membrane 4. Conversely, a larger sealing force F D A smaller value improves the freedom of movement of the membrane 4, but leads to a deterioration in the quality of the seal and the associated risk of leakage. D The size of may be set to an optimum value depending on the process parameters (in particular the pressure and / or temperature in the cavity 5) by means of a device 17 for varying the sealing force.

[0062] The sealing force F shown in Figure 2 D is the friction force F between the membrane and the seal R Friction force F R acts along the membrane surface, i.e., parallel to the surface of the membrane 4, i.e., in a direction approximately horizontal in FIG. R always points in the opposite direction to the movement of the membrane 4. The membrane 4 can expand and contract, especially thermally induced, and therefore the friction force F R can have different directions (represented by double arrows in FIG. 2). For example, in the case of expansion of the membrane 4 in the workspace 8, the friction force F R opposes the movement of the membrane 4 outward from the workspace 8. In the case of contraction of the membrane 4 in the workspace 8, the friction force F R opposes the movement of the membrane 4 into the workspace 8. The friction force F R The magnitude of the sealing force F D The frictional force depends on the magnitude of the friction coefficient, and in many cases there is an approximately linear relationship within certain limits (the ratio between the frictional force and the contact pressure is also called the "coefficient of friction").

[0063] Furthermore, a pretension force F is applied to the membrane 4. V is shown in Figure 2. The pretension force F V acts along the membrane surface, thus parallel to the surface of the membrane 4, i.e., approximately horizontally in FIG. 2. VThe magnitude of the pretension force F can also be set or varied, i.e., using the device 18 for varying the pretension. V Setting or changing may be achieved, for example, by changing the pretension of the spring 15 .

[0064] FIG. 3 shows an enlarged view of a portion of the apparatus 1 from FIG. 1C. The two press tools 2 and 3 are positioned in a closed position. Pressure and / or temperature are applied to the membrane 4, so that the pressure and / or temperature can also be applied to the workpiece 19 via the membrane. To achieve uniform application of pressure and / or temperature to the workpiece 19, the membrane 4 should be in substantially continuous contact with the workpiece 4. However, due to the application of pressure and / or temperature to the membrane 4, expansion of the membrane 4, particularly thermally induced expansion, is possible. The two press tools 2 and 3 may also expand due to the application of pressure and / or temperature, particularly thermally induced expansion. The expansion of the membrane 4 is typically greater than the expansion of the press tools 2 and 3. This is due to the fact that the membrane 4 is typically made of a material with a lower thermal expansion coefficient than the material from which the press tools 2 and 3 are made. The press tools 2 and 3 are typically made of Invar, for example. Due to the expansion of the membrane 4, the membrane surface of the membrane 4 widens and / or the membrane 4 stretches, which risks the expanding membrane 4 expanding into the cavity 5, in particular bulging into the cavity 5. The expansion of the membrane 4 into the cavity 5 is shown by way of example using dashed lines in FIG. 3 . The expansion of the membrane 4 into the cavity 5 results in the membrane 4 peeling away from the workpiece 19 and therefore no longer being in substantially continuous contact with the workpiece 19, making it impossible to uniformly apply pressure and / or temperature to the workpiece 19 using the membrane 4. To counteract the expansion of the membrane 4 into the cavity 5, pressure is therefore applied to the membrane 4, in particular using the working medium in the cavity 5. This application of pressure may in particular be the application of pressure and / or temperature to the membrane 4 using the working medium in the cavity 5 described above. In this regard, the pressure applied to the membrane 4 must be at least equal to, and preferably greater than, the pressure at which the membrane 4 expands in the direction of the cavity 5.

[0065] The application of pressure to the membrane 4 generates an expansion force F along the membrane surface of the membrane 4. A The expansion force F AIn that regard, preferably, the pressure applied to the membrane 4 is dissipated at least partially along the membrane surface of the membrane 4. By applying pressure to the membrane 4, the membrane 4 is also at least partially pressed against the workpiece 19 being machined or fabricated. As a result, the membrane is at least partially "clamped" (represented by the arrows in FIG. 3 ) between the workpiece 19 and the pressure applied to the membrane 4. Due to this clamping, the membrane 4 can only expand substantially along the membrane surface of the membrane 4, which also results in an expansion force F along the membrane surface of the membrane 4. A contributes to the creation of

[0066] In order for the expanding or expanded membrane 4 not to peel off from the workpiece 19 but to be in substantially continuous contact with the workpiece 19, the membrane surface of the membrane 4 must be expanded and / or the surface or section of the membrane 4 that is expanded must also be guided out of the working space 8. Otherwise, the membrane may sag adjacent to the press tools 2, 3, and in particular adjacent to the gap 11. To guide the membrane 4 at least partially out of the working space 8, the membrane 4 must be passed through the seal 16. In that regard, the passage of the membrane 4 through the seal 16 is effected by an expansion force F acting along the membrane surface of the membrane 4. A However, the friction force F R opposes the passage of the seal 16 by the membrane 4, and a sealing force F D Therefore, the expansion force F A is at least adjacent to the seal 16 and has a friction force F R For the membrane 4 to pass through the seal 16, the friction force F between the membrane 4 and the seal 16 must be R The sum of the forces acting along the membrane surface of the membrane 4 acting adjacent to the seal 16, as opposed to the friction force F between the membrane 4 and the seal 16, is preferably R The friction force F between the membrane 4 and the seal 16 must be greater than RThe sum of the forces acting along the membrane surface of the membrane 4 acting adjacent to the seal 16 in opposition to the expansion force F adjacent to the seal 16 is, in relation thereto, at least A Preferably, the expansion force F A is the friction force F R If it is greater, no additional force is required to force the membrane 4 through the seal 16. However, in addition, the pretension force F can be applied to the membrane 4 using a device for varying the pretension. V may also help force the membrane 4 through the seal 16. The expansion force F adjacent to the seal 16 A and the expansion force F A Pretension force F acting in the same direction as V In this case, the sum of and is the expansion force F A The friction force F between the membrane 4 and the seal 16 acting against R To simplify the passage of the seal 16 through the membrane 4, the sealing force F D can be defined as being reduced by a device 17 for varying the sealing force upon application of pressure and / or temperature to the membrane.

[0067] After sufficient pressure and / or temperature has been applied to the workpiece 19, the two press tools 2, 3 can be returned to the open position shown in Figures 1A and 1B. The workpiece can then be removed from the apparatus 1.

[0068] 4A shows a second configuration of an apparatus 1' for carrying out the method according to the invention in a cross-sectional view in an open position with no workpiece inserted. The apparatus 1' differs substantially from the apparatus 1 from FIGS. 1A to 3 in that the apparatus 1' comprises a second membrane 4B'. However, the function of the two apparatuses 1, 1' is basically the same. Therefore, in the present case, particular details will be given of the differences between the two apparatuses 1, 1'.

[0069] The apparatus 1' shown in FIG. 4A includes a first upper press tool 2' and a second lower press tool 3'. The two press tools 2', 3' can be moved relative to each other, for example, vertically (as indicated by the arrows in FIG. 4A) between an open position and a closed position. Furthermore, the apparatus 1' includes a first upper membrane 4A' and a second lower membrane 4B', where the first membrane 4A' is connected to the first press tool 2' and the second membrane 4B' is connected to the second press tool 3'. A first cavity 5A' for a working medium is formed between the first membrane 4A' and the first press tool 2', and a second cavity 5B' for a working medium is formed between the second membrane 4B' and the second press tool 3', where the working medium may be, for example, oil. The membranes 4A', 4B' are made of metal and preferably have a thickness ranging between 0.2 mm and 3.5 mm. The cavities 5A', 5B' can each be filled with a working medium through channels 6'. Both in the first press tool 2' and in the second press tool 3' there are provided holes 7' through which a heating medium and / or a cooling medium can be led.

[0070] The apparatus 1 shown in Figure 4A also has a working space 8' into which a workpiece (not shown in Figure 4A) can be inserted. The working space 8' extends partly into the first press tool 2' and partly into the second press tool 3'. The two press tools 2', 3' have guides 9' which can be formed, for example, by protrusions 9A' and recesses 9B', where the protrusions 9A' may be provided on the second press tool 3' and the recesses 9B' may be provided on the first press tool 2'.

[0071] The first membrane 4A' is connected to the first press tool 2' in the following way (the same applies to the second membrane 4B' and the second press tool 3'): the first press tool 2' has in its edge area a gap 11' through which the first membrane 4A' is led. The gap 11' opens into a hollow space 12' in which a clamping device 13' is provided, in which the first membrane 4A' is clamped. The clamping device 13' is led out of the first press tool 2' through the opening, where it is pressed outwards by a spring 15' which supports it on its outer surface, thereby applying a pretension, in particular a pretension force F V 1. The tension anchor 14' is connected to the spring 15', which is capable of providing a pretension, in particular a pretension force F V A device 18' for varying the pretension is also provided, which allows the pretension to be varied. A seal 16' is provided in the gap 11', which allows movement of the first membrane 4A' to seal the first cavity 5A'. Adjacent to the seal 16', a device 17' for varying the sealing force is also provided.

[0072] FIG. 4B shows the apparatus 1' from FIG. 4A in the open position with a workpiece 19' inserted. The previously described areas of the apparatus 1' are also provided in FIG. 4B with the corresponding reference numbers. The difference from the position shown in FIG. 4A is that the workpiece 19' has been inserted into the working space 8' of the second press tool 3'. In addition to the workpiece 19', two further workpieces 19A' are inserted into the working space 8' of the apparatus 1. The workpieces 19A' may be, for example, prefabricated reinforcement elements with a Z-shaped cross section (e.g., aircraft fuselage "spars"). The workpieces 19A' are to be bonded to the workpieces 19' in a subsequent manufacturing step. To enable uniform pressure distribution despite the complex geometry of the workpieces 19A', several cores 20' whose shape matches the shape of the working space 8' and the shape of the workpieces 19, 19A' are inserted into the working space.

[0073] FIG. 4C shows the apparatus 1' from FIG. 4A in the closed position. The previously described areas of the apparatus 1' are also provided in FIG. 4C with the corresponding reference numerals. The apparatus 1' is closed by moving the two press tools 2', 3' toward the closed position. In the closed position shown in FIG. 4C, pressure and / or temperature are applied to the workpiece 19'. The pressure and / or temperature are applied in the manner described in connection with the first configuration of the apparatus 1 for carrying out the present method. In this second embodiment, the two cavities 5A', 5B' may be filled with the working medium independently of each other, but the two cavities 5A', 5B' are preferably filled with the working medium uniformly. Pressure and / or temperature may also be applied independently to the working medium in the two cavities 5A', 5B' and / or to the two membranes 4A', 4B'. Alternatively or additionally, pressure and / or temperature is applied uniformly to the working medium in the two cavities 5A', 5B' and / or to the two membranes 4A', 4B'.

[0074] 5 shows an enlarged view of a portion of the apparatus 1' from FIG. 4C. The two press tools 2', 3' are in the closed position. Pressure and / or temperature are applied to the two membranes 4A', 4B' so that pressure and / or temperature can also be applied to the workpiece 19' by means of the membranes 4A', 4B'. The cavities 5A', 5B' are also sealed by the respective membranes 4A', 4B' with a sealing force F D Each membrane 4A', 4B' is preferably sealed by a seal 16' applying a sealing force F D The seal 16 is at least partially sealed by the respective seals 16' pressing with a sealing force F D The sealing force F acts perpendicular to the surfaces of the membranes 4A' and 4B', i.e., in a direction substantially perpendicular to the surface of the membranes 4A' and 4B' in FIG. D The magnitude of the respective sealing force F can be varied by a respective device 17' for varying the sealing force, and the respective device 17' for varying the sealing force D can be varied independently.

[0075] However, the device 17' for varying the sealing force preferably varies the respective sealing force FD As already explained for the first configuration of the device 1 for carrying out the method, the respective sealing forces F D are the respective friction forces F between the respective membranes 4A', 4B' and the respective seals 16'. R Friction force F R thereby acting along the membrane surface of each membrane 4A', 4B', and therefore parallel to the surface of each membrane 4A', 4B'.

[0076] Even in this second configuration of the device 1', a problem arises: due to the application of pressure and / or temperature to the membranes 4A', 4B', this can result in, in particular, thermal expansion of the membranes 4A', 4B'. The two press tools 2', 3' can also expand, in particular thermally, due to the application of pressure and / or temperature, with the expansion of the membranes 4A', 4B' usually being stronger than that of the press tools 2', 3'. As already explained for the first configuration of the device 1, the membrane surfaces of the respective membranes 4A', 4B' can widen and / or the membranes 4A', 4B' can stretch, which risks causing the expanding membranes 4A', 4B' to expand into the respective adjacent cavities 5A', 5B'. By way of example, the expansion of the membranes 4A', 4B' into the respective cavities 5A', 5B' is indicated by dashed lines in FIG. 5. In this configuration of the device 1', a pressure is also applied to the membranes 4A', 4B', in particular by means of a working medium in the respective cavity 5A', 5B', in order to counteract the expansion of the membranes 4A', 4B' into the respective cavities 5A', 5B'. This application of pressure may in particular be the application of pressure and / or temperature to the membranes 4A', 4B' as previously described, in particular by means of a working medium in the respective cavity 5A', 5B'. The pressure applied to the membranes 4A', 4B' must in each case be at least equal to, and preferably greater than, the pressure with which the respective membrane 4A', 4B' expands in the direction of the respective adjacent cavity 5A', 5B'. The pressure can thereby in each case be applied to the membranes 4A', 4B' independently of one another or uniformly. The application of pressure to the membranes 4A', 4B' results in a respective expansion force F along the membrane surface of the respective membranes 4A', 4B'. A This results in:

[0077] As already described with respect to the first configuration of the device 1, each membrane 4A', 4B' is swelled by a distension force F A The friction forces F R The friction force F between each membrane 4A', 4B' and each seal 16' is RThe sum of the forces acting along the membrane surface of each membrane 4A', 4B' acting adjacent to the respective seal 16', against the respective friction forces F between the respective membranes 4A', 4B' and the respective seal 16' is preferably R In this case, it can be stipulated that this sum of forces per membrane 4A', 4B' may be of different magnitudes or equal. Furthermore, the expansion forces F adjacent to each seal per membrane 4A', 4B' are A can be applied to each membrane 4A', 4B' using a respective device 18' for varying the pretension, and a respective expansion force F per membrane 4A', 4B' A Pretension force F acting in the same direction as V The expansion forces F adjacent to the seal 16 may be different or equal in magnitude. A and the expansion force F A Pretension force F acting in the same direction as V The sum of the sealing force F and the sealing force F may be different or equal for the membranes 4A' and 4B'. D The variations may be effected independently or uniformly by a device 17 for varying the sealing force per membrane 4A', 4B'. [Explanation of symbols]

[0078] 1, 1' device 2, 2' First (upper) press tool 3, 3' Second (lower) press tool 4, 4A', 4B' Membranes 5, 5A', 5B' cavity 6, 6' Channel 7, 7' hole 8,8' workspace 8A Dent 9,9' guide 9A, 9A' protrusion 9B, 9B' recess 10 Edge Elements 11, 11' gap 12, 12' hollow space 13, 13' clamping device 14, 14' tension anchor 15, 15' spring 16, 16' seal 17, 17' Device for varying the sealing force 18, 18' Device for changing pretension 19, 19', 19A' Workpieces 20' Core F A Expansion force F D Sealing force F R friction force F V Pretension force

Claims

1. 1. A method for producing molded parts, in particular from fiber composite materials, comprising: a) a first press tool (2, 2'), a second press tool (3, 3'), at least one membrane (4, 4A', 4B'), at least one seal (16, 16'); A device (1, 1') comprising: - said first press tool (2, 2') and said second press tool (3, 3') are movable relative to each other between an open position and a closed position; a working space (8, 8') for a workpiece (19, 19', 19A') is formed between said first press tool (2, 2') and said second press tool, - said membrane (4, 4A', 4B') is at least partially arranged between said first press tool (2, 2') and said second press tool (3, 3'); - said membrane (4, 4A', 4B') is at least partially arranged in said working space (8, 8'); at least in said closed position, at least one cavity (5, 5A', 5B') for a working medium is formed between said membrane (4, 4A', 4B') and said first pressing tool (2, 2') and / or said second pressing tool (3, 3'), - said cavity (5, 5A', 5B') can be at least partially sealed by said seal (16, 16'), at least in said closed position; - applying a sealing force (F) to the membrane (4, 4A', 4B') by means of the seal (16, 16') to seal the cavity (5, 5A', 5B'); Ｄ ) can be applied, the membrane (4, 4A', 4B') and the first press tool (2, 2') and / or the second press tool (3, 3') have different coefficients of thermal expansion; Providing a device (1, 1'); b) applying a sealing force (F) to the membranes (4, 4A', 4B') using the seals (16, 16'); Ｄ ) applying - the cavities (5, 5A', 5B') are connected to the membranes (4, 4A', 4B') by the sealing force (F Ｄ ) at least partially sealed by applying a voltage - the sealing force (F Ｄ ) creates a friction force (F Ｒ ) is applied, Steps and c) applying pressure and / or temperature to the membrane (4, 4A', 4B') by means of a working medium in the cavity (5, 5A', 5B'), - said membrane (4, 4A', 4B') expands more than said first press tool (2, 2') and / or said second press tool (3, 3'), at least partially in said working space (8, 8'); - pressure is applied to said membrane (4, 4A', 4B') by means of a working medium in said cavity (5, 5A', 5B'), - the pressure opposes the expansion of the membrane (4, 4A', 4B') into the cavity (5, 5A', 5B'), thereby generating an expansion force (F) along the membrane surface. Ａ ) - the expansion force (F Ａ ) is the friction force (F) between the membrane (4, 4A', 4B') and the seal (16, 16') at least adjacent to the seal (16, 16'). Ｒ ) to compete with Steps and Including, The membrane (4, 4A', 4B') can be passed through the seal (16, 16'), and in step c) the membrane (4, 4A', 4B') is subjected to the expansion force (F Ａ ) at least partially through said seal (16, 16'); A method characterized by:

2. 2. The method for producing molded parts according to claim 1, characterized in that steps b) and c) overlap at least in time.

3. The expansion force (F Ａ ) is the friction force (F) between the membrane (4, 4A', 4B') and the seal (16, 16'). Ｒ 3. A method for producing a molded part according to claim 1 or claim 2, characterized in that the thickness of the molded part is greater than 1 mm.

4. The following is carried out after step a) and before step b) and / or before step c): a1) providing at least one workpiece (19, 19', 19A'); a2) inserting the workpiece (19, 19', 19A') into the device (1, 1'), in particular into the working space (8, 8'); a3) moving the first press tool (2, 2') and / or the second press tool (3, 3') to the closed position; A method for producing a molded part according to any one of claims 1 to 3, comprising:

5. 5. The method for manufacturing a molded part according to claim 1, wherein the device (1, 1') provided in step a) comprises at least one device (18, 18') for varying the pretension of the membrane (4, 4A', 4B').

6. The following is carried out after step a) and before step b) and / or step c): a4) applying a pretension to said membrane (4, 4A', 4B') by means of a device (18, 18') for varying said pretension; 6. A method for producing a molded part according to claim 5, comprising:

7. The pretensioning of the membranes (4, 4A', 4B') in step a4) applies a pretensioning force (F Ｖ ) is applied, and in particular during step b) and / or step c), the pretension force (F Ｖ ) is the friction force (F Ｒ 7. The method for producing a molded part according to claim 6, wherein the thickness of the molded part is less than 1 / 2 mm.

8. During step b) and / or step c), a pretension force (F Ｖ 8. The method for producing molded parts according to claim 7, characterized in that the pretension is varied, in particular reduced, by the device for varying the pretension (18, 18').

9. In particular, the expansion force (F Ａ ) and pretension force (F Ｖ ) is the friction force (F Ｒ 9. A method for producing a molded part according to claim 7 or claim 8, characterized in that the thickness of the molded part is greater than 1 / 2 mm.

10. 10. A method for producing a molded part according to any one of claims 1 to 9, characterized in that during step b) and / or step c) the pressure and / or temperature of the working medium in the cavity (5, 5A', 5B') is changed.

11. 11. The method for manufacturing molded parts according to any one of claims 1 to 10, characterized in that the device (1, 1') provided in step a) comprises, adjacent to the seal (16, 16'), at least one device (17, 17') for varying the sealing force.

12. The device (1') provided in step a) comprises at least one second membrane (4B'), at least in said closed position, at least one second cavity (5B') for a working medium is formed between said at least second membrane (4B') and said first press tool (2') and / or said second press tool (3'); - applying a sealing force (F) to said second membrane (4B') by means of at least one second seal (16') to seal said second cavity (5B'); Ｄ ) can be applied, and - said second membrane (4B') can be passed through said second seal (16'); A method for producing a molded part according to any one of claims 1 to 11, characterized in that it comprises a membrane.

13. 13. The method for manufacturing a molded part according to any one of claims 1 to 12, characterized in that in step b) and / or in step c) the pressure of the working medium arranged in the cavity (5, 5A', 5B') is increased to at least 1.2 bar, in particular 2 bar, and in step b) and / or in step c) the pressure of the working medium arranged in the cavity (5, 5A', 5B') is increased to a maximum pressure in the range between 10 bar and 50 bar, in particular between 15 bar and 30 bar.

14. 14. The method for manufacturing a molded part according to any one of claims 1 to 13, characterized in that in step b) and / or in step c), the temperature of the working medium placed in the cavity (5, 5A', 5B') is raised to a maximum temperature in the range between 280°C and 500°C, in particular between 310°C and 410°C.

15. After step b) and / or after step c), c) opening the device (1, 1') and removing the workpiece (19, 19', 19A'); A method for producing a molded part according to any one of claims 1 to 14, comprising:

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