METHOD AND PLANT FOR CONSOLIDATING FIBER COMPOSITE STRUCTURES

Abstract

A method for consolidating a fiber composite structure with at least one thermoplastic and/or thermoelastic polymer includes arranging the structure between a plate-shaped base and a plate-shaped cover in a loading/unloading station of a conveying device. The cover is sealed with respect to the base by a seal to be displaceable in relation to the base. The method includes generating negative pressure in the interstice between the base and the cover so the ambient pressure pushes the cover against the base, the structure being clamped between the cover and the base; heating the composite structure by electromagnetic radiation preferably at least into the range of the melting temperature of the at least one polymer in a heating station, cooling the composite structure in a cooling station of the conveying device; and removing the consolidated structure from the base or removing the base onto which the structure has been placed.

Claims

1. A method for consolidating a fiber composite structure with at least one thermoplastic and/or thermoelastic polymer, comprising: arranging the fiber composite structure between a plate-shaped base and a plate-shaped cover in a loading/unloading station of a conveying device, the cover being sealed with respect to the base by a sealing element so as to be displaceable in relation to the base, generating a negative pressure in the interstice between the base and the cover so that the ambient pressure pushes the cover against the base, and the fiber composite structure is clamped between the cover and the base; heating the fiber composite structure by electromagnetic radiation preferably at least into the range of the melting temperature of the at least one thermoplastic and/or thermoelastic polymer in a heating station of the conveying device; cooling the fiber composite structure in a cooling station of the conveying device; and removing the consolidated fiber composite structure from the base or removing the base onto which the consolidated fiber composite structure has been placed from the conveyor device.

2. The method according to claim 1, characterized in that the consolidated fiber composite structure is fed to a press, in particular a stamping press, after having been removed from the conveying device.

3. The method according to claim 1, characterized in that, after the fiber composite structure has been arranged on the base, the base is lifted out of the conveying device by a lifting table and moved toward the cover, and/or the cover is held above the conveying device by holding elements and moved toward the base.

4. The method according to claim 1, characterized in that the cover is released from the at least one holding element as soon as a negative pressure is built in the gap between the base and the cover, and the lifting table deposits the arrangement composed of the base, cover and fiber composite structure placed therebetween in the conveying device, preferably in the loading/unloading station.

5. The method according to claim 1, characterized in that an identification of bubble formation is carried out during the compression of the fiber composite structure, in the case of bubble formation, the pressure in the interstice being temporarily increased and/or the cover being lifted to achieve an at least partial reduction in the contact of the cover with the fiber composite structure, and thus enable a local ventilation path for removing the air or vapor.

6. The method according to claim 5, characterized in that the identification of bubble formation takes place by monitoring the magnitude of the negative pressure in the interstice and/or by detecting the temperature distribution in the fiber composite structure by a thermographic camera, the presence of a bubble being inferred when a local cold spot identifiable in the thermal image is present relative to a hot surrounding area.

7. The method according to claim 1, characterized in that the cooling in the cooling station is carried out by way of a self-contained surface cooling system, in particular a cooling table, the surface cooling system being in contact with the base and/or with the cover.

8. The method according to claim 1, characterized in that the surface cooling system is designed as a cooling table which can lift the arrangement composed of the base, cover and fiber composite structure placed therebetween out of the conveying device and supply it to further surface cooling via the cover.

9. The method according to claim 1, characterized in that the fiber composite structure is cooled in the cooling station to a temperature which is below the melting temperature and above the softening temperature of the at least one thermoplastic and/or thermoelastic polymer, or which is below the softening temperature of the at least one thermoplastic and/or thermoelastic polymer.

10. The method according to claim 1, characterized in that the fiber composite structure is cooled in the cooling station to a temperature below 150 C., preferably below 120 C., particularly preferably below 100 C.

11. The method according to claim 1, characterized in that the heating of the fiber composite structure is carried out by electromagnetic radiation before, concurrently with, or after compressing the fiber composite structure between the cover and the base.

12. The method according to claim 1, characterized in that the conveying device is designed to be rotatable.

13. The method according to claim 1, characterized in that the cover and/or the base are designed as or comprise a glass panel.

14. A system for consolidating a fiber composite structure, characterized in that the system comprises a conveying device comprising a loading/unloading station, a heating station and a cooling station, and the system is configured: to deposit the fiber composite structure on a base in the loading/unloading station, or to introduce a base including a fiber composite structure into the system, and to position a cover over the base and, by a vacuum pump, to generate a negative pressure in the interstice between the cover and the base, and further to move the base and the cover including the fiber composite structure placed therebetween to the heating station; in the heating station, to heat the fiber composite structure by the at least one radiation source preferably at least into the range of the melting temperature of the at least one thermoplastic and/or thermoelastic polymer and, by the vacuum pump, to maintain or further increase the negative pressure in the interstice to compress the fiber composite structure between the cover and the base; after compression has been carried out, to move the base (20) and the cover including the compressed fiber composite structure placed therebetween to the cooling station, and to cool the arrangement composed of the base, cover and fiber composite structure placed therebetween in the cooling station; and after cooling has taken place, to move the base and the cover including the fiber composite structure placed therebetween to the loading/unloading station, and in the loading/unloading station, to lift the cover off the base by holding elements to remove the consolidated fiber composite structure from the base, or to remove the base onto which the consolidated fiber composite structure has been placed.

15. The system according to claim 14, further comprising a press, in particular a stamping press.

16. The system according to claim 14, characterized in that the conveying device is designed as a rotary table.

17. The system according to claim 14, characterized in that a lifting table is arranged in the loading/unloading station to move the base together with the fiber composite structure placed thereon away from and toward the conveying device, and/or a holding element is arranged to hold the cover above the conveying device and move it toward and away from the base.

18. The system according to claim 14, characterized in that the system comprises a sensor for detecting the pressure in the interstice and/or a thermographic camera for detecting an image of the temperature distribution in the fiber composite structure, the system further comprising a control unit configured to determine that a bubble is present upon identification of a sudden rise in pressure or a local cold spot identifiable in the thermal image relative to a hot surrounding area and, when a bubble is present, to instruct the vacuum pump and/or the bracing units designed as actuators to temporarily increase the pressure in the interstice and/or lift the cover, so as to achieve an at least partial reduction in the contact of the cover with the fiber composite structure and thus enable a local ventilation path for removing the air or vapor.

19. The system according to claim 14, characterized in that a self-contained surface cooling system, preferably a cooling table, is arranged in the cooling station, which can lift the arrangement composed of the base, cover and fiber composite structure placed therebetween out of the conveying device and deposit it, and which can achieve a cooling effect through the base, and/or a self-contained surface cooling system, preferably a cooling table, is arranged in the cooling station, which can be moved toward the cover and can achieve a cooling effect through the cover.

20. The system according to claim 14, characterized in that the cover and/or the base is designed as or comprises a glass panel.

21. A system for consolidating a fiber composite structure, characterized in that the system comprises a conveying device comprising a loading/unloading station, a heating station and a cooling station, and the system is configured: to deposit the fiber composite structure on a base in the loading/unloading station, or to introduce a base including a fiber composite structure into the system, and to position a cover over the base and, by a vacuum pump, to generate a negative pressure in the interstice between the cover and the base, and further to move the base and the cover including the fiber composite structure placed therebetween to the heating station; in the heating station, to heat the fiber composite structure by the at least one radiation source preferably at least into the range of the melting temperature of the at least one thermoplastic and/or thermoelastic polymer and, by the vacuum pump, to maintain or further increase the negative pressure in the interstice to compress the fiber composite structure between the cover and the base; after compression has been carried out, to move the base and the cover including the compressed fiber composite structure placed therebetween to the cooling station, and to cool the arrangement composed of the base, cover and fiber composite structure placed therebetween in the cooling station; and after cooling has taken place, to move the base and the cover including the fiber composite structure placed therebetween to the loading/unloading station, and in the loading/unloading station, to lift the cover off the base by holding elements to remove the consolidated fiber composite structure from the base, or to remove the base onto which the consolidated fiber composite structure has been placed, characterized in that the system is configured to carry out the method according to claim 1.

Description

[0057] The invention will be described hereafter with reference to the drawings:

[0058] FIG. 1 shows a method for consolidating a fiber composite structure according to the prior art:

[0059] FIGS. 2A to 2E show a method for consolidating a fiber composite structure according to a first preferred embodiment;

[0060] FIGS. 3A to 3C show a method for consolidating a fiber composite structure according to a second preferred embodiment;

[0061] FIGS. 4A and 4B show a method for consolidating a fiber composite structure according to a third preferred embodiment;

[0062] FIGS. 5A to 5E schematically explain a method for consolidating a fiber composite structure having an elevation, according to another preferred embodiment; and

[0063] FIGS. 6A to 6B schematically explain the arrangement of the stations on a conveying device; and

[0064] FIGS. 7A and 7B schematically explain a method for consolidating a fiber composite structure having an elevation, according to another preferred embodiment; and

[0065] FIG. 8 illustrates the composition of a radiation source and the heating of a fiber composite structure.

[0066] With reference to FIGS. 2A to 2E, first, a method for consolidating a fiber composite structure according to a first preferred embodiment will be described.

[0067] As is shown in FIG. 2A a fiber composite structure 10, which is preimpregnated with thermoplastic or thermoelastic polymers or mixed with such polymers in a solid, or dissolved, or deposited state, is arranged on a plate-shaped base 20. With the provision of a sealing element 15, in particular an elastic annular seal which surrounds the fiber composite structure 10 laterally and preferably at a distance, a plate-shaped cover 30 is further positioned over the fiber composite structure arranged on the base 20. The base 20 and the cover 30 are each formed of a heat-resistant material that allows electromagnetic radiation, in particular infrared radiation, to pass. Particularly preferably, the base 20 and the cover 30 are each designed as glass panels. For example, the cover 30 and the base 20 may each be designed as rectangular glass panels having a width of 500 mm, 1000 mm, 1500 mm, 2000 mm or more, and a length of 1000 mm, 1500 mm, 2000 mm, 2500 mm or more. The thickness of the glass panel can be, for example, 2 mm, 3 mm, 5 mm or more.

[0068] So as to prevent the base 20 from sagging downwardly by virtue of its own weight, it is preferably provided that the base 20 is support from below, for example by being placed partially or across the entire surface area on a table top or on another support structure (not shown) which supports the base 20 from below. It is likewise conceivable to design the base 20 to have a greater thickness than the cover 30, for example to use a glass panel measuring 5 mm or 8 mm for the base 20, while a glass panel measuring 2 mm or 3 mm is used for the cover 30. In this case, the base 20 will have inherently greater rigidity and, accordingly, will tend to deflect less than the cover 30.

[0069] So as to provide easier handling of the cover 30 and the base 20, these can each be fastened to a support frame. The support frame can have a one-piece or multi-piece design, and can surround the cover 30 and the base 20 completely or partially at the side edges thereof. Correspondingly, FIG. 2A shows, by way of example, that two support frame elements 21 and 31 are arranged on the cover 30 and the base 20, respectively. An example of a support frame composed of support frame elements 31 which completely surrounds or encloses the cover 30 can be seen in FIG. 2E, which shows a top view from above of an exemplary cover 30. Lateral projections, recesses or the like (not shown) can be provided on the support frame elements 31 for handling the cover 30, in particular for positioning the cover 30 over the base 20, which allow corresponding hooks or other holding elements (not shown) to engage in the support frame 31 and thus in the cover 30. If a glass panel is used for the cover 30 and/or the base 20, the glass panel can, for example, be fixedly connected to the corresponding support frame elements 21, 31 by adhesive bonding. Other types of fastening, such as screwing, or also clamping in a groove provided in a support frame element 21, 31 and which surrounds and clamps the glass panel on both sides, are likewise conceivable.

[0070] Again with reference to FIG. 2A, actuators 32, in particular pneumatic actuators, are arranged on the support frame elements 31 arranged on the cover 30, the actuators being activatable using a preset pressure to extend a respective cylinder 33 to a predefined stroke limit. Via the cylinders 33, which are braced on the support frame elements 21 arranged on the base 20, the actuators 32, in particular the pneumatic actuators, can thus position and hold the support frame elements 31 arranged on the cover 30 at a predefined height over the support frame elements 21 arranged on the base 20. The actuators 32, together with the cylinders 33, can therefore be regarded as a bracing device, which braces the cover 30 with respect to the base 20. The force of all actuators 32, in particular of the pneumatic actuators, is greater than the weight exerted as dead weight of the cover 30 and the support frame elements 31. In this way, by applying the preset pressure to the pneumatic actuators, the cover 30 can be held and/or positioned in a predefined position over the base 20 and the fiber composite structure 10 arranged on the base 20.

[0071] In this position, it can advantageously be provided that the cover 30 is located at a height of 2 to 20 mm above a target thickness when consolidation is completed, and/or the cover 30 is located at a height of at least 0.1 mm, preferably at least 1 mm, more preferably at least 3 mm, and particularly preferably at least 5 mm above the surface of the fiber composite structure 10. It should be taken into account here that the cover 30 in this position can undergo inherent flection by virtue of the dead weight thereof and only lateral retention by the support frame elements 31. The degree of this inherent flection is essentially determined by the selection of the material of the cover 30, particularly the stiffness and specific weight thereof, as well as the thickness, width and length of the cover 30. Particularly preferably, the material and the thickness of the cover 30 are selected in such a way that the inherent flection is in a range between 2 and 20 mm, preferably in a range between 3 and 15 mm, particularly preferably in a range between 5 and 10 mm. Correspondingly, the cited height information is to be understood in this case as height information with respect to the deepest point of the bottom surface of the cover 30. FIG. 2A shows further radiation sources 14 which are arranged above the cover 30 and beneath the base 20 and which are configured to emit electromagnetic radiation for heating the fiber composite structure 10. Alternatively, it is likewise possible to arrange only one radiation source 14 above the cover 30 or beneath the base 20. The radiation sources 14 are preferably implemented as infrared light sources. The radiation source 14 arranged beneath the base 20 can optionally also be arranged in the support structure (not shown) for the base 20. The radiation sources 14 are preferably designed as panel heaters, which irradiate the cover 30 and/or the base 20 essentially across the entire surface area and with substantially uniform surface radiation density. It shall be noted that in the following FIGS. 2B to 2D the radiation sources 14 are not shown for the sake of clarity.

[0072] The interstice sealed by the cover 30, the base 20 and the sealing element 15 is then evacuated with the aid of a pump or the like (not shown) so that a negative pressure arises in the interstice. Due to the pressure difference arising on the cover 30 between ambient pressure, on the one hand, and negative pressure in the interstice, on the other, a compressive force arises on the cover 30, as is illustrated by the arrow in FIG. 2B. Since the cover 30 is held at the lateral edges (here, for example, the edges in the longitudinal direction of the cover 30, 30) by the support frame elements 31, and these are held in position at a height by means of the actuator 32 and the cylinders 33, the compressive force exerted on the cover 30, together with the dead weight of the cover 30, results in flection of the cover 30, so that the cover curves downwardly, as is also schematically illustrated in FIG. 2B.

[0073] With increasing negative pressure, the force exerted on the cover 30 will increasingly grow, so that the cover 30 will increasingly deflect and will rest first on the fiber composite structure 10 in the center. In other words, the cover 30 only makes contact with the fiber composite structure 10 in a relatively small subsection A of the surface of the fiber composite structure 10, as is schematically illustrated in FIG. 2C. As the negative pressure increases, the subsection A will increase, and the boundaries thereof will gradually migrate to the outside.

[0074] The cover 30 thus presses, in an increasingly larger region, on the fiber composite structure 10, which has preferably been heated by the radiation sources 14 to such an extent that the thermoplastic or thermoelastic polymers have melted even in the core of the fiber composite structure 10.

[0075] As soon as the sum of the weight brought about by the dead weight of the cover 30 and the support frame elements 31 (as well as possibly further support frame elements 31 provided on the cover 30 and/or other elements) and the force exerted on the cover 30 due to the negative pressure, minus the compressive force introduced into the fiber composite structure 10 via the subsection A, exceeds a predetermined level, in particular the level of the maximum lifting force of the actuators 32, in particular of the pneumatic actuators, pressure limiting valves provided on the actuators 32 open. As a result, the support frame members 31 are able to be lowered, as is illustrated by the arrows in FIG. 2C, and the cover 30 bears completely against the base 20 until the cover 30 makes full contact with the fiber composite structure 10, as is shown in FIG. 2D. The support frame elements 21 and 31 can be designed and dimensioned so as to define a stop, which defines the distance between the base 20 and the cover 30 with respect to each other when they are completely closed, thus defining the target thickness of the fiber composite structure 10 to be consolidated. However, it is preferred that the support frame members 21 and 31 are each designed to be flush with the corresponding surfaces of the cover 30 and the base 20, and that a stop delimiting the compression and defining the target thickness of the fiber composite structure 10 is provided in another manner. For example, the minimum stroke limit of the actuators 32, in particular of the pneumatic actuators, can be used as a stop, wherein the actuators 32 are arranged and fastened in a position relative to the support frame elements 31 in such a way that the position defined by the minimum stroke limit of the actuators 32 corresponds to the desired target thickness of the fiber composite structure 10 to be compressed. Alternatively, a separate stop may also be provided, such as a stop element that is arranged between the support frame members 21, 31 and/or between the base 20 and the cover 30 and dimensioned, in terms of thickness, so as to correspond to the target thickness of the fiber composite structure 10 to be compressed.

[0076] The compression and consolidation of the fiber composite structure 10 therefore does not take place simultaneously across the entire surface area, as is the case, for example, with the method explained with reference to FIG. 1. Rather, the fiber composite structure 10 is compressed successively and in a controlled manner toward the outside, proceeding from a narrow subsection A, by means of the bent cover 30 so that the displacement of fiber and polymer material, which is caused by the local action of the compressive force exerted by the bent cover 30, causes air trapped in the fiber composite structure 10 or vapors forming as a result of heating, to be pushed out and, after only a relatively short distance, to reach a region in which the cover 30, by virtue of the flection thereof, does not yet, or not yet strongly, push on the fiber composite structure 10, so that the trapped air or vapors forming as a result of heating can escape more easily out of the fiber composite structure 10 into the interstice and be removed via the connected vacuum pump. This makes it possible to consolidate the fiber composite structure 10 substantially without the formation of air inclusions, or with only very small air inclusions or pores, and thus form it into a high-grade laminate of high quality.

[0077] Furthermore, it is also conceivable for an identification of bubble formation to be carried out during the compression of the fiber composite structure. For example, a pressure sensor can be used to measure the (negative) pressure predominating in the interstice, which can be evaluated by the control unit. If a rapid increase in pressure is measured, the control unit can rate this as the formation of a bubble, for example by evaporation of liquid. Alternatively or additionally, it can also be provided to detect and evaluate the surface of the fiber composite structure 10 with the aid of a thermographic camera in the form of a thermal image. The control unit can watch for the presence of local hot spots or local cold spots in the thermal image. A local hot spot, that is, a location at which the temperature of the fiber composite structure 10 shown in the thermal image is significantly higher than the temperature in surrounding areas can, for example, indicate the presence of foreign bodies, which heat up more quickly and to a higher temperature than the impregnating polymer under the influence of the electromagnetic radiation. Conversely, a local cold spot, that is, a location at which the thermal image indicates a significantly lower temperature than for surrounding locations, may indicate an air or vapor bubble. The reason is that, when a bubble is present, polymer and fiber material is displaced by the bubble. Since hot polymer and fiber material emits more infrared radiation, which is detected by the thermographic camera, than a vapor or air bubble (even if it has the same temperature), the thermal image will therefore appear darker in this area.

[0078] In this way, the control unit can cause the vacuum pump to be throttled so that the pressure in the interstice increases, and less negative pressure prevails, when the control unit detects bubble formation. The cover 30 will therefore bend less, and the subsection A in which the cover 30 is supported on the fiber composite structure 10 will become narrower. Concurrently or alternatively, the control unit can also actuate the actuators 32, in particular the pneumatic actuators, to extend the cylinders 33 further, and thereby lift the cover 30 on the sides, which likewise narrows the subsection A in which the cover 30 is supported on the fiber composite structure 10. In this way, improved ventilation of the fiber composite structure 10, in particular removal of the bubbles, can be ensured.

[0079] After the fiber composite structure 10 has been compressed in this way and consolidated to form a laminate, also referred to as a tailored blank, and after the laminate is cooled, the cover 30 can be opened. This can be carried out in a simple manner by switching off the vacuum or the negative pressure in the interstice and lifting off the cover 30. However, it is preferred to proceed in the reverse order compared to the sequence shown in FIGS. 2A to 2D. Thus, if the negative pressure continues to exist in the interstice, the actuators 32, in particular the pneumatic actuators, are charged with compressed air to bend the cover 30. The cover 30 thus curves upwardly at the lateral ends and detaches locally from the consolidated laminate. Afterwards, the negative pressure in the interstice is successively reduced so that the cover 30 gradually detaches from the laminate, and the laminate peels off the cover 30 in this way. This has the advantage that the laminate can be separated from the cover 30 more reliably and without destruction.

[0080] While above, in particular, the use of pneumatic actuators as bracing units was described, this has no limiting effect, and it is also possible to use other actuators 32 or devices to support the cover 30 with respect the base 20. For example, hydraulic actuators, electromotive actuators or other actuators can also be used as bracing units, in particular also servo actuators, which, under the control of a control unit, make it possible to position the cover 30 in terms of height and/or to exert a predefined force.

[0081] The method can preferably be carried out in a system (not shown) for consolidating a fiber composite structure 10 which comprises a loading/unloading station, a pressing station and a cooling station.

[0082] In the loading/unloading station, the base 20 can be made accessible, for example, to an operator in such a way that the operator can place a fiber composite structure, such as a tape structure laid in the tape laying method, onto the base 20. The cover 30 is placed on or above the base 20 via a holder provided in the system, which can engage, for example, on the support frame or the support frame elements 31 of the cover 30, so that the fiber composite structure 10 is arranged in the interstice sealed by means of a sealing element 15, as described above with reference to FIG. 2A.

[0083] The base 20, together with the fiber composite structure 10 arranged thereon and the cover 30 arranged thereabove, can then be moved to the pressing station in which the fiber composite structure 10 is irradiated and heated by the radiation sources 14, for example to a temperature in the range between 200 and 400 C., depending on the impregnating polymer, until the core of the fiber composite structure 10 is molten. In the pressing station, it can be provided that a lifting table is arranged, which is preferably designed with a flat table surface, to lift the base 20 off a conveying device (not shown), which ensures the transport in the system, and thus bring it into a well-defined position. Afterwards, the vacuum is built up in the interstice, and the compression is carried out as described in more detail in FIGS. 2B to 2D.

[0084] After compression has taken place, the entirety of the base 20, the cover 30 and fiber composite structure 10 pressed therebetween is moved to the cooling station, preferably while a vacuum continues to be applied.

[0085] A cooling table can be provided in the cooling station, onto which the base 20 is placed or which can be lifted so as to be brought in contact with the base 20. Likewise, a cooling device may be provided which is brought in contact with the cover 30 from above. Alternatively, the cooling table can lift the base 20 until the cover 30 is brought in contact with the cooling device. By means of the cooling table and the cooling device, the cover 30 and the base 20, and indirectly the fiber composite structure 10, are cooled, for example, until the fiber composite structure 10 is cooled at the core to a temperature below 150 C., preferably below 100 C., and the impregnating polymer solidifies.

[0086] Thereafter, the entirety of the base 20, the cover 30 and the fiber composite structure 10 pressed therebetween can be moved to the loading/unloading station in which the cover 30 is lifted off, and the operator can remove the fiber composite structure fully consolidated to form the laminate.

[0087] With reference to FIGS. 3A to 3C, a second embodiment of the invention will now be described. The second embodiment essentially differs from the first embodiment in that spring elements 35 are provided instead of the actuators 32 used in the first embodiment. The spring elements 35 are preferably mounted in the support frame elements 31 of the cover 30 and, due to the inherent spring force, support the cover 30 with respect to the base 20 or the support frame elements 21 of the base 20. The spring elements 35 can be designed as simple springs. However, it is preferred that the spring elements 35 are designed with degressive spring characteristics. In this way, it can be achieved that, in the event of initial loading of the spring elements 35, in this case as a result of the increasing negative pressure in the interstice, only slight compression of the spring elements 35 takes place initially, so that, as is shown in FIG. 3B, the cover 30 again undergoes flection, which causes the cover 30 in the narrow portion A to rest on and be braced against the fiber composite structure 10. With increasing negative pressure, and thus increasing loading of the spring elements 35, the spring elements 35 reach the region of a flatter gradient of the degressive spring characteristic, so that the spring elements 35 undergo increasingly greater compression and, accordingly, the lateral ends of the cover 30 are increasingly lowered. The subsection A, in which the cover 30 is supported on the fiber composite structure 10, therefore increasingly grows in width until the cover 30 is ultimately in contact across the entire surface area with the fiber composite structure 10 and compresses the same, as is shown in FIG. 3C. Here as well, it can preferably again be provided that a control unit activates the vacuum pump in such a way that a desired chronological progression of the (negative) pressure in the interstice is set, so as to control and/or regulate a desired progression of the flection of the cover 30, and thus a desired progression of the compression, taking into account the spring characteristics of the spring elements 35.

[0088] So as to avoid excessive compression of the fiber composite structure 10, as is further shown in FIGS. 3A to 3C, it can preferably be provided to provide stop pieces 36 between the cover 30 and the base 20 and/or between the corresponding support frame elements 31, 21. The stop pieces 36 are dimensioned in the height thereof to correspond to the target thickness of the consolidated fiber composite structure 10. The stop pieces 36 can be made of a metal, for example. However, the stop pieces 36 are preferably formed of a temperature-resistant plastic material, in particular having low specific heat capacity. This has the advantage that these stop pieces 36 likewise cool rapidly when the fiber composite structure 10 is cooled, and there is no resulting effect that the stop pieces 36 remain hot beyond the cooling process and, when the next fiber composite structure 10 is introduced, this is heated prematurely and undesirably locally, which could lead to uneven compression and consolidation. The stop pieces 36 can be arranged between the fiber composite structure 10 and the sealing element 15. Alternatively and preferably, these stop pieces can also be arranged downstream of or behind the sealing element 15 to respond flexibly and quickly to a changed target thickness of the fiber composite structure, without paying particular attention to the sealing element 15 since this can remain at its location.

[0089] A third embodiment of the invention is described in FIGS. 4A and 4B. As shown, spacers 40 are provided in this embodiment, which are arranged between the base 20 and the cover 30 and/or optional corresponding support frame elements (not shown in FIGS. 4A and 4B). The spacers 40 can, for example, be fixedly connected to the base 20. The spacers 40 have a height corresponding to the target thickness of the fiber composite structure 10 to be consolidated, in addition to a small oversized dimension, preferably in the range between 0.1 and 0.5 mm. The spacers 40 can likewise be formed of metal or preferably of a temperature-resistant plastic material, in particular having low specific heat capacity. The spacers 40 are preferably arranged at a distance between 20 and 200 mm from the outer edge of the fiber composite structure 10.

[0090] As is shown in FIGS. 4A and 4B, the spacers 40 likewise have the effect of supporting the cover 30, so that the cover 30 is again bent under the action of the negative pressure in the interstice.

[0091] With reference to FIGS. 5A to 5E, a further embodiment of the invention will now be shown. In particular, a situation such as can be found in the loading/unloading station 12 is illustrated here. A fiber composite structure 10 is arranged on the base 20, which is embedded in support frame elements 21. The base 20 or the support frame elements 21 are situated on the conveying device 11 which in this area has a cut-out through which a lifting table 22 can be moved in the direction of the conveying device 11. The cover 30, held in the support frame elements 31, is arranged at a distance above the base. The cover 30 or the support frame elements 31 are held at a distance from the base 20 by a plurality of holding elements 37 to allow the fiber composite structure to be placed onto the base 20 and/or the sealing element 15 to be inserted. The holding elements 37 hold the cover 30 or the support frame elements on isolated points or surface areas, but preferably not peripherally across the entire surface area. After the fiber composite structure 10 and the sealing element 15 have been deposited on the base 20, the lifting table 22 is displaced in the direction of the conveying device 11 and lifts the base out of the conveying device 11, as shown in FIG. 5B. The lifting table 22 is displaced in the direction of the cover 30 until the cylinders 33 make contact with the support frame elements 21, or until the sealing element 15 is in contact both with the cover 30 and with the base 20 and forms an interstice which can be evacuated by means of a vacuum pump. The cover 30 and the base 20 can also be moved horizontally with respect to one another by the lifting table 22 and the holding elements 37, whereby the cover 30 can be optimally aligned with respect to the base 20. Due to the resulting negative pressure in the interstice between the cover 30 and the base 20, the base 20 and the cover 30 move the base 20 and the cover 30 toward one another. Furthermore, the weight of the cover 30 and the force resulting from the negative pressure in the interstice create a force-fit connection between the base 20 and the cover 30 via the cylinders 33 and the sealing elements 15, whereby the cover 30 can be detached from the holding elements 37 and now rests on the support 20. The cover 30 and the base 20 are also fixed in the their position with respect to one another by the force-fit connection and cannot be displaced with respect to one another.

[0092] As the cover 30 increases the contact area thereof with the fiber composite structure 10 due to the negative pressure in the interstice between the cover 30 and the base 20, the lifting table can move the arrangement composed of the base 20, the fiber composite structure 10 and the cover 30 downwardly in the direction of the conveying device 11. The cover 30 can also already rest completely on the fiber composite structure 10, as is illustrated in FIG. 5D. The cover 30 should preferably be in nearly complete contact with the fiber composite structure 10 when the lifting table 22 deposits the arrangement composed of the base 20, the fiber composite structure 10 and the cover 30 on the conveying device 11, as is illustrated in FIG. 5E. After having deposited the arrangement, the lifting table 22 can be moved out of the effective range of the conveying device 11 so that, in the present case, the arrangement composed of the base 20, fiber composite structure 10 and cover 30 can be moved from the loading/unloading station 12 to the next station, that is, the heating station 13, so as to be heated there to a temperature preferably above the melting temperature of the at least one thermoplastic polymer.

[0093] In a further embodiment, the lifting table 22 could also be equipped with a radiation source 14, in particular with infrared tubes 51, 52, and a procedure as is described in FIGS. 5A to 5E could be carried out, and in the heating station 14, after the fiber composite structure 10 has been deposited on the base 20. The fiber composite structure 10 would be heated by the lifting table 22, comprising the integrated radiation source 14, from the side of the base 20. Furthermore, a further radiation source, as is shown in FIG. 4A, for example, could be arranged in the heating station 14 above the cover 30. The holding elements 37, which hold the cover 30 or the support frame elements 31 on isolated points or surface area, do not interfere, since they are arranged outside the effective range of the radiation source.

[0094] Alternatively, as described above, the lifting table 22 could also be used in a cooling station 14, wherein it would then preferably be equipped with a cooling unit, in particular a surface cooling system. The lifting table 22 could move the arrangement composed of the base 20, the fiber composite structure 10, and the cover 30 in the direction of a further cooling unit, which can cool the fiber composite structure 10 via the cover 30.

[0095] FIGS. 6A and 6B schematically illustrate two embodiments for arranging the various stations for the consolidation of a fiber composite structure 10. The loading/unloading station 12, the heating station 13 and the cooling station 14 are preferably arranged on a conveying device 11 designed as a rotary table, which is mounted so as to be rotatable about a center of rotation. The respective units, such as radiation sources 14 or cooling unit, are arranged in a stationary manner at the individual stations, and the conveying device 11 moves the arrangement composed of the base 20, the fiber composite structure 10 and the cover 30 to the respective stations. The conveying device 11 preferably has a cut-out, on the edge of which the support frame elements 21 of the base 20 can rest. Due to the cut-outs, it is possible, for example, for a lifting table 22 to pick up the base 20 out of the conveying device 11, or for the fiber composite structure 10 to be heated or cooled in the heating station 13 or the cooling station 14 via the cover 30 and the base 20.

[0096] Alternatively, the loading/unloading station 12 can also be divided into two separate units, as in FIG. 6B, so that the conveying device 11 comprises a loading station 12 and an unloading station 12. This arrangement may be useful when loading and unloading of the fiber composite structure 10 represent a bottleneck in terms of the cycle time. In particular in the case of fiber composite structures that have a low target thickness and therefore heat and cool rapidly, the division of the loading/unloading station 12 into a loading station 12 and an unloading station 12 can further increase the cycle time for consolidating the fiber composite structure 10, and thus also the throughput through such a system.

[0097] The above-described embodiments are in particular suitable for compressing and consolidating flat fiber composite structures 10, that is, fiber composite structures 10 having a substantially uniform thickness. For an increasing number of uses and areas of application of fiber-reinforced components, however, there is the requirement that these components should have local reinforcements, for example in component regions to which later hinges are to be attached or which are to be connected to other components. For such applications, the fiber composite structures 10 are already laid with corresponding locally reinforced sections, for example in the form of tailored blanks formed in the tape laying process. So as to compress such locally reinforced fiber composite structures 10 provided with elevations and consolidate these to form a laminate, it is provided in a further preferred embodiment, as shown in FIGS. 7A and 7B, to use an adapted cover 30.

[0098] FIG. 7A schematically shows a fiber composite structure 10, which here, by way of example, comprises a locally reinforced section having an elevation E in a central region. It is further provided for the cover 30 to be designed with a cavity K corresponding to the elevation E. The cavity K in the cover 30 can be formed, for example, by milling. In FIG. 7B, which shows a view of the cover 30 from beneath, it is apparent that the cavity K surrounds the elevation E with a circumferential gap S. The gap S preferably has a width between 3 and 15 mm, particularly preferably between 5 and 10 mm. By providing such a gap S, a free flow channel is provided, via which, under the action of the negative pressure and by means of the vacuum pump (not shown), air trapped in the fiber composite structure 10, in particular in the region of the elevation E, or vapors forming due to heating can be suctioned off and discharged.

[0099] The free flow and discharge of air and vapors is supported in particular by the flection of the cover 30, as described above, which can ensure that the gap S toward one side of the cover 30 does not come in contact with the surface of the fiber composite structure 10 until a late point in time, and thus it is closed, at which point in time substantial extraction by suction has already taken place for the region of the elevation E. Alternatively or additionally, active ventilation of the gap S can also be provided, for example by temporarily increasing the pressure in the interstice or by reducing the vacuum, and/or by raising the cover 30 to achieve an at least partial reduction in the contact of the cover 30 with the fiber composite structure 10 and thus allow venting of the gap S. It may likewise be considered to provide a venting channel, which can be incorporated into the surface of cover 30 in the form of a narrow groove, for example, or in the form of a borehole extending through cover 30 and likewise connected to the vacuum pump. Other types of venting the gap S are also conceivable.

[0100] As is apparent from FIGS. 7A and 7B, the fiber composite structure 10 and the cover 30 form substantially complementary geometries, so that the overall geometry of the base 20, fiber composite structure 10 and cover 30 has a substantially plate-like shape having a constant thickness.

[0101] The advantage is exploited that, in particular, a cover 30; designed as a glass panel has a substantially similar heat capacity as the materials customarily used in fiber composite structures 10. For this reason, given an uniform surface radiant power of the radiation sources 14, the locally reinforced section of the elevation E, that is, the thicker section of the fiber composite structure 10, can be thoroughly heated in the same time as the thinner areas of the fiber composite structure 10, due to the thinner glass layer of the cover 30 in this area.

[0102] The cavity K is preferably designed undersize to compensate for the shrinkage of the material as a result of the consolidation.

[0103] As is further apparent in FIG. 7B, the cavity K is preferably designed with undercut corner radii H, so that it is also possible to process elevations E having sharp-edged corners. This is, in particular, advantageous when the fiber composite structures to be compressed and consolidated are formed by a tape laying process, in which rectangular tape sections are usually processed and laid to form a desired fiber composite structure.

[0104] The cover 30 provided with a cavity K can suitably be used as a cover 3 or 30 in the methods for consolidation described and/or mentioned herein, so as to suitably enable the described methods to consolidate fiber composite structures 10, 10 having differences in elevations.

[0105] With reference to FIG. 8, furthermore an exemplary embodiment of the radiation sources 14 will be explained. As is shown in FIG. 6, the radiation sources 14 preferably comprise a plurality of infrared tubes 51, 52 that extend transversely to the cover 30 or the base 20. The infrared tubes 51, 52 are preferably designed and arranged to generate a uniform surface radiant power so as to allow the fiber composite structure 10 to be heated as uniformly as possible. Particularly preferably, it is provided that the infrared tubes 51, 52 can be selectively switched on individually or in groups, so that only necessary areas are irradiated, depending on the size, shape and position of the fiber composite structure 10. For example, in the example of FIG. 6, the infrared tubes 52 extending across the fiber composite structure 10 can be switched on, while the infrared tubes 51 that do not overlap the fiber composite structure 10 remain switched off This can be used for saving energy, and thus for lowering costs. It can likewise be provided that, in regions in which irradiation with infrared light is only partially needed or desired, a screen element 55 is provided to prevent the cover 30 or the base 20 from being irradiated and heated in this region in which no proportion of the fiber composite structure 10 is located, or the upper and lower radiation sources 14 from mutually heating one another on their own through the cover 30 and the base 20 in this region, due to the absent fiber composite structure 10, and thereby expose one another to thermal loading and possibly premature aging.

LIST OF REFERENCE SIGNS P1547

[0106] 1, 10, 10 fiber composite structure

[0107] 2, 20 base

[0108] 3, 30, 30 cover

[0109] 4, 14 radiation source

[0110] 5, 15 sealing element

[0111] 6 pipe socket

[0112] 11 conveying device

[0113] 12, 12, 12 loading/unloading station

[0114] 13 heating station

[0115] 14 cooling station

[0116] 21 support frame element

[0117] 22 lifting table

[0118] 31 support frame element

[0119] 32 actuator

[0120] 33 cylinder

[0121] 35 spring element

[0122] 36 stop piece

[0123] 37 holding element

[0124] 40 spacer

[0125] 51, 52 infrared tubes

[0126] 55 screen element

[0127] A subsection

[0128] E elevation

[0129] H corner radius

[0130] K cavity

[0131] S gap