WO2012136391A1

WO2012136391A1 - Device and method for producing fiber preforms, which are a precursor in the production of fiber-reinforced plastic components in particular

Info

Publication number: WO2012136391A1
Application number: PCT/EP2012/051287
Authority: WO
Inventors: Marco Göttinger; Michael Kaiser
Original assignee: Voith Patent Gmbh
Priority date: 2011-04-08
Filing date: 2012-01-27
Publication date: 2012-10-11
Also published as: DE102011007022A1

Abstract

The invention relates to a device and a method for producing fiber preforms (28), which are a precursor in the production of fiber-reinforced plastic components in particular. The device has multiple winding stations (3, 4), multiple grippers (5, 5.1), and at least one first molding tool (15). Each gripper (5, 5.1) can be moved back and forth on a path between a maximum position (8, 8.1) and a pick-up position (9, 9.1), said pick-up position (9, 9.1) being provided at a thread transferring point (14, 14.1) and being closer to the winding station (3, 4) than the maximum position (8, 8.1). One or more rewinding devices are provided with which threads or rovings that were dispensed into the region between the thread transferring points (14, 14.1) and the first molding tool (15) can be at least partly drawn into the region between the thread transferring points (14, 14.1) and the winding stations (3, 4) and/or can be wound at the winding stations (3, 4).

Description

Apparatus and process for the production of fiber preforms, which are in particular a precursor in the production of fiber-reinforced plastic components

The invention relates to an apparatus for the production of fiber preforms, which in particular constitute a precursor in the production of fiber-reinforced plastic components, the apparatus having a plurality of unwinding stations for providing a plurality of yarns or rovings, a plurality of grippers, each having one or more yarns or rovings on its Beginning, and having at least a first forming tool, each gripper being reciprocally movable on a path between a maximum position and a picking position, and wherein the picking position is provided at a yarn transfer point and closer to the unwinding station than the maximum position.

Furthermore, the invention relates to a process for the production of fiber preforms which, for example, represent a precursor in the production of fiber-reinforced plastic components, in particular using a device according to the invention, which has the following process steps in succession:

- Clamping yarns or rovings using multiple grippers

- Drape the yarns or rovings over a first mold

- Separating the yarns or rovings. Fiber-reinforced plastic consists of matrix material, which among other things gives the rigidity and of fibers, which are embedded in the matrix material and which among other things provide the tensile strength. Fiber-reinforced plastic is used especially for heavily loaded components, which should still be as light as possible. Since the fibers impart no strength in the transverse direction, the fibers must be aligned so that their longitudinal direction coincides as well as possible with the respective loading direction. To achieve this, the fibers often have to be laid in different directions. The better and more precisely the fiber layer is adapted to the load, the better the component will be. For components made of fiber-reinforced plastic, there are numerous manufacturing processes. For the production of large numbers of well-applicable methods, however, there are currently only with rotationally symmetrical or plate- or strand-shaped components by winding or plate or extrusion.

Complex high-quality 3-D structures, however, can only be very expensive to produce, since the production of the required fiber preform is difficult, slow and expensive. High quality structures are usually made with continuous fibers. In many processes, fiber preforms are first produced corresponding to the desired three-dimensional component shape, so-called preforms, which predominantly consist of fibers which are often arranged one above the other in several layers in order to achieve the necessary fiber directions. Subsequently, the fiber preforms are then soaked or coated with the matrix material, sometimes pressed and finally cured. Both for the production of the fiber preforms and for the impregnation and / or curing of the components molding tools can be used according to the desired component shape, on or in which the Faservorform ling or the component is placed and / or pressed. So that the fiber preforms have sufficient dimensional stability for further processing, they are provided with small amounts of adhesive or binder and fixed after the three-dimensional draping, for example by drying or by heating and cooling. The fiber preforms are usually created by superimposing and fixing of prefabricated and pre-bonded flat semi-finished products. Such semi-finished products are for example tapes or fabrics, scrims or nonwovens in which a multiplicity of individual yarns or rovings are already woven, sewn or glued into a flat structure. A yarn is referred to when using so-called continuous fibers, ie when the fibers are unwound from a coil or a ball. Numerous yarns that are untwisted simultaneously from a spool or from a ball are called yarn bundles or roving. The rovings can consist of up to several ten thousand single yarns, which are also called filaments.

The required individual parts are cut from the flat semifinished product, which is usually available as a roll product, according to a kind of pattern, as is known from DE 10 2008 011 658 A1. Then they are placed over a mold and connected or pressed together. An example of the production of such semi-finished products by gluing or sewing is also shown in DE 10 2008 01 1 658 A1. Often, however, a high proportion of manual activities is necessary. A device for the mechanical production of simple one-dimensionally curved preforms with sections of semifinished products, which are held in a cassette and then deposited on a core, is known from DE 10 2008 042 574 A1. More complex shapes can not yet be produced mechanically.

Another possibility for producing fiber preforms for more complex components is automated fiber laying. In this case, narrow bundles of yarns or bundles of yarn bundles are guided back and forth by a fiber laying head over the molding tool, and deposited, pressed and fixed next to and above one another. For complex components, a complex robot-like control of the fiber laying head is necessary. Even with the use of two, three or even four fiber lay heads in parallel, the production speed is still relatively slow, as the heads often have to travel long distances and successive narrow fiber bundles are used. Furthermore, they have a very long and complicated yarn tracking from the creel to the multi-axis moving laying head. Such yarn tracking in hoses with special guide blades to prevent twisting of the rovings is shown for example in US 2008/0202691 A1. The object of the invention is to provide an apparatus and a method for the production of Faservorform lingen, so that more complex, high-quality structures can be easily automated, but flexible in the shape and fiber orientation, faster and cheaper to manufacture. The object is achieved by the device with the features according to claim 1. Further advantageous features are mentioned in the dependent claims. According to the invention, the device is characterized in that one or more rewinding devices are provided, with which yarns or rovings which have been dispensed into the area between the yarn transfer points and the first mold can be at least partially withdrawn into the area between yarn transfer points and unwinding stations and / or the unwinding stations can be wound up. As a result, unnecessary waste, as obtained in particular when using sheet-like semi-finished products on a large scale, avoided since already spent but not required fiber material can be back-stored and reused. The manufacturing process is thereby simpler and faster and can be done in parallel, and in addition it can be adapted particularly flexible to different component shapes. Especially in the serial production of strongly three-dimensionally shaped Faservorform the advantages come into play. Thus, several yarns or rovings can be spread simultaneously, quickly and controlled side by side. The device is thereby designed so that deposition rates of more than 2 kg / min or even more than 3 kg / min of yarn or roving material can be achieved. Furthermore, both the unwinding stations and the yarn guide can remain stationary by the grippers. Since the usual flat semi-finished products are dispensed with and the fiber preform is draped and produced directly from yarns or rovings, the material costs are much lower than known processes. Due to the parallelization, a short production time can nevertheless be achieved. The flat semi-finished products are quite expensive due to the prefabrication. In the case of strongly three-dimensional components, the use of large-area semi-finished products also entails the risk of wrinkling. In small-scale on the other hand increases the cost of cutting and joining the items. The rewind means may be formed, for example, by the yarn dispensers or by the unwind stations, if a direction reversed drive or clutch is provided. But they can also be a separate device. Instead of being rewound onto the bobbins or bobbins, the withdrawn yarn length may also be stored by a corresponding extension of the yarn path, for example, by shifting yarn guide elements until further use. The feeding of the device with yarns or rovings takes place from the unwinding stations. The unwinding stations can be designed, for example, as a so-called creel. The yarns or rovings can be drawn from bobbins or bobbins. Each yarn transfer point receives yarn or rovings from one or more unwind stations. Also preferred is a separating device which can separate the yarns or rovings between a forming tool and the grippers, and / or a separating device which can separate the yarns or rovings between a forming tool and the yarn transfer points. Preferably, each gripper has its own maximum position and is assigned to its own yarn transfer point, so that the grippers are individually movable on essentially parallel paths. This results in simple yarn paths and rewinding is easily possible. It is advantageous if the grippers can take various individual intermediate positions in their path and if they can hold the respective beginnings of the yarns or rovings at these intermediate positions. This results in the separation of the yarns or rovings between gripper and mold less waste.

In particular, the device according to the invention is designed so that the individual grippers can each be moved on a substantially linear path from the pickup position to the maximum position. This results particularly simple thread guides with low friction. For more complicated yarn guides, braiding of the yarns can hinder rewinding.

The invention can be used particularly advantageously if at least 5 grippers, preferably at least 10 grippers, more preferably at least 20 grippers, are present, in particular if the grippers have a clamping width of 10 to 500 mm, preferably 20 to 200 mm, and / or if all Grippers together have a total clamping width of at least 1 m, preferably of at least 2 m, more preferably of at least 3 m.

In the apparatus, the first and / or a second forming tool can be brought between the yarn transfer points and at least some of the grippers, in particular so that thereby the yarns or rovings are draped over the forming tool.

Furthermore, a control of the yarn tensions of the yarns or rovings may be provided. When driving a forming tool into the tensioned yarn or roving layer, the yarns are deflected by the forming tool and the yarn tension would change uncontrollably. By controlling the yarn tension during the manufacturing process and in particular during draping can be controlled. This is important, as the yarns or rovings must not be overloaded, but on the other hand should not be too loose in order to achieve optimum structural strengths. When using sheet semis, however, the fibers can only be applied largely without tension. And when depositing with a fiber laying head, the yarn must be placed according to the three-dimensionality of the shape with exactly calculated yarn excess length in the form of loops or the like, so that the yarns then during draping, ie when entering or closing the molds, have the stretched length. By controlling the yarn tensions, the normally necessary calculation of the laying webs, which is complicated and time-consuming, can be dispensed with. The yarn tension control is important, even if several grippers when clamping the yarns or rovings at different intermediate positions, in particular close and along an outer contour of a molding tool, stand. Later, this results in little waste of expensive fiber material. However, the resulting strong deflections of the yarns or rovings can be controlled only with a control of the yarn tensions.

Preferred is a separating device which can separate the yarns or rovings between the first and / or a second forming tool and the grippers, and / or a separating device which can separate the yarns or rovings between the first and / or a second forming tool and the yarn transfer points , intended.

In particular, a separator for the yarns or rovings is provided between a forming tool and the yarn transfer points, which is adapted to separate the yarns or rovings close to an outer contour of the first and / or a second mold, in particular closer to the mold than at the yarn transfer points.

Furthermore, it is advantageous that each rewinding device, in particular each unwinding station or each group of unwinding stations, is assigned its own coupling and / or braking device, which are preferably designed such that each rewinding device, in particular each unwinding station or each group of unwinding stations, has different lengths withdraw from yarns or rovings. Especially with very strong three-dimensional shapes fall on different issued yarn lengths.

Particularly preferably, one or more sensors are provided which can detect the positions of the beginnings of the yarns or rovings in the area of the yarn transfer points. This can be used to detect when the beginnings are at the desired position for picking up with the gripper and when the rewinding must be stopped. Such sensors may be camera-based, other optical, electrical or mechanical sensors. It is also conceivable to use a yarn tension measurement as a sensor. Furthermore, it is advantageous if one or more spreaders are provided in the area of the yarn transfer points, in particular as a kind of comb with one or more rows of prongs. As a result, the individual yarns or rovings are kept clean in their course both during dispensing and when rewinding. They ensure that the yarns or rovings lie as widely as possible next to each other or are stretched and do not slip sideways when draped. In addition, the spreader can also be provided with a clamping or braking device and the spreader can also be movable along the yarn paths or gripper paths. For example, a certain yarn tension for rewinding can be maintained.

Furthermore, it is advantageous to assign each unwinding station or each group of unwinding stations at least one device for measuring the respective yarn tensions, which is arranged in the area of the yarn transfer point and / or between the unwinding station and the yarn transfer point and which is preferably designed as a ring force sensor at a deflection point. This ensures that each yarn or roving bundle has controlled yarn tension and can be controlled individually or in small groups.

A plurality of unwinding stations, preferably a maximum of ten, particularly preferably a maximum of six, can be combined to form a group which has only one yarn tension control. To be sufficiently flexible, there should be at least as many unwind stations or groups of unwind stations as there are grippers.

Advantageously, each unwinding station or group of unwinding stations is assigned its own coupling and / or braking device. Furthermore, the yarn tensions for each unwinding station can be controlled individually. As a result, a common drive can be provided at the unwinding stations or the yarn transfer points for the delivery of the yarns. The individual clutch and / or brake devices control then the appropriate yarn tension or separate and connect the drive with yarns.

Furthermore, the first and / or a second molding tool can be equipped with a heating device and / or a pressing device. By increasing the temperature or pressure, an existing binder can be activated, so that the yarns or rovings are fixed in the predetermined shape and connected to one another first to a layer and then to the fiber preform. As a binder material, for example, threads or nonwovens, which consist at least partially of thermoplastic or adhesive, are draped with. As a result, the binder material necessary for fixing is applied directly to the fiber material. The binder material can also be introduced by hybrid threads, which also contain binder material in addition to fiber material, or by coating or spraying the yarns or rovings. The binder material may also be applied, for example sprayed, onto a forming tool after draping the yarns and rovings. By fixing a layer of yarns or rovings, a certain stability is achieved for the application of another layer of yarns or rovings or for the further processing of the fiber preform. A pre-activation of the binder material already when dispensing the yarns or rovings should be dispensed with, as this would prevent the rewinding.

The object is achieved by the method with the features according to claim 12, in particular in connection with a device according to one of the device claims. Further advantageous features for the method are mentioned in the dependent claims.

According to the invention, the method is characterized in that, after the separation, the yarns or rovings which have been dispensed into the area between the yarn transfer points and the first mold are at least partially drawn back into the area between yarn transfer points and unwinding stations and / or at the unwinding stations. The advantages achieved thereby correspond to those already mentioned in the device.

In order for the draped yarns or rovings to retain the desired shape, the yarns or rovings can be fixed in a dimensionally stable manner after and / or during draping, in particular by activation of binder material, and preferably by heating and / or pressing. For the completion or further processing of the fiber preforms, it may be advantageous if the fixing takes place separately and / or after the last layer in each layer.

In order to obtain very little waste, the yarns or rovings can be separated during separation and close to and along an outer contour of the first or a second mold. Furthermore, it is advantageous that the positions of the beginnings of the yarns or rovings in the region of the yarn transfer points are detected with one or more sensors. The retraction of the yarns or rovings is then stopped at a certain signal from the sensor. Preferably, for each unwinding station or for each group of unwinding stations, a separate detection of the beginnings of the yarns or rovings takes place.

Draping is the forming or shaping of yarns or rovings with the aid of a molding tool. Draping may be accomplished in one or more stages by moving the molding tool or dies simultaneously or sequentially into the plyed or roving ply.

Furthermore, the yarn tensions during draping can be kept essentially constant, preferably at the values which are present at the beginning of draping, and more preferably at the same value. That is to say, the yarn tensions, when the yarns or rovings are stretched, are brought to the desired values, in particular all to the same value, brought and then they are kept constant during draping or reshaping.

It is also advantageous if the yarn tensions are measured in the area of the yarn transfer points and / or between the unwinding stations and the yarn transfer points.

In a serial production, it can be provided that the method is carried out several times in succession for depositing a plurality of layers of yarns or rovings on the first mold. This can be done within a device according to the invention or the mold is transported after placing and fixing the one layer and the rewinding of the yarns or rovings in one or more other devices according to the invention, in each of which a further layer of yarns or rovings launched by the inventive method becomes.

By way of embodiments, further advantageous features of the invention will be explained with reference to the drawings. They show in Figures 1 a - 7 b, a preferred embodiment of the device according to the invention in different process steps:

Fig. 1a side view while gripper yarns or rovings fetches

Fig. 1b shows top view while gripper yarns or rovings

Fig. 2a side view after tensioning the yarns or rovings

Fig. 2b Top view after tensioning the yarns or rovings

Fig. 3a side view after a first Drapierschritt the first layer

FIG. 3b shows a plan view after a first draping step of the first layer. FIG

Fig. 4a side view after a second Drapierschritt the first layer

Fig. 4b top view after a second Drapierschritt the first layer

Fig. 5a side view after the separation of the yarns or rovings

Fig. 5b top view after the separation of the yarns or rovings

Fig. 6a side view after turning the molds and pick up yarns or rovings for the second layer during gripper Fig. 6b top view after turning the molds and during

Grab the yarn or rovings for the second layer

Fig. 7a side view after a second Drapierschritt the second layer

7b shows a top view after a second draping step of the second layer and in FIGS. 8a-c a further preferred embodiment of the device according to the invention in various method steps:

Fig. 8a top view after application of the first layer

Fig. 8b top view after applying another layer

Fig. 8c top view after applying yet another layer.

Hereinafter, the figures and the embodiments will be described in more detail. In a particularly preferred embodiment of the device and the method, the device is suitable for this purpose or the device performs the following method steps successively or partly parallel to one another:

- Providing the yarns or rovings and possibly the binder material

- Grasping the required yarns or rovings and possibly the binder material

- Clamping the required yarns or rovings by appropriate positioning of the gripper

- First draping over a first mold

Second draping with a second mold

- Fix the layer of yarn or rovings

- Separating the yarns or rovings on both sides of the molds

- Rewind the issued and unnecessary yarns or rovings

- Opening the molds

- Turning and / or passing a molding tool with the applied layer

Repeating the process for applying further layers in the same device or in one or more further devices according to the invention until the completion of the fiber preform. As the fiber material for the yarns or rovings, fibers such as carbon (carbon), glass, or aramid or other fibers may be used. And as a matrix material for the fiber-reinforced plastic are, for example, thermoplastic or thermosetting plastic, epoxy resin, other plastic (polymers) or other resin in question. The binder material may be thermoplastic or adhesive. It can either already be present as hybrid yarn or hybrid roving, ie individual fibers or yarns are made of binder material, or it can be spanned together with the yarns or rovings from the gripper or it is applied or sprayed onto the draped yarns or rovings.

In Fig. 1a and 1b, the basic structure of the device can be seen. The provision of the yarns or rovings takes place via a multiplicity of unwinding stations, in which the fiber material is provided in the form of bobbins or yarn bobbins (so-called bobbins) and which are arranged in several rows 1, 2 next to one another, one behind the other or one above the other. The coils may also, as shown in Fig. 1a, form an upper and a lower row. The beginnings of the yarns or rovings 20 are shown schematically only in the respectively used area for the unwinding stations 3,4 used. All other beginnings are threaded to the corresponding yarn transfer points 14, so that they can be detected by the associated grippers in the pick-up positions 9. Such a thing is called together as a creel. On the other hand, the grippers 5 are shown in their maximum positions 8, which in this case also correspond to the starting positions. The clamping width of a gripper is b and the total clamping width of all grippers is B. Even if only equal width gripper are shown, of course, grippers with different widths are possible. The grippers do not necessarily have their maximum and pickup positions in a line. Furthermore, a first mold 15 on a lifting table 17 and a second mold 16, which is designed as a hood, so shown in the down position outside the paths of the gripper. The second mold is in plan view not shown. And a corresponding movement or lowering device for the second mold is not shown separately. Furthermore, there is a binder material supply 19, which may for example be arranged between the rows of unwinding stations.

A gripper 6 is in pick-up position and fetches the yarns or rovings corresponding to its arrangement in the device by grasping their beginnings. The gripper is closed by a guide device 7, e.g. a linkage or a piston, movable. The grippers can move individually, but only linearly and on parallel paths next to each other between the pick-up position and the maximum position, thus enabling simple automation and fast parallel movement. As shown, several unwinding stations can be combined into one group and assigned to a gripper. A gripper can grab several yarns or rovings together. In any case, at least as many unwinding stations as grippers should be provided.

Fig. 2 a and 2 b represent the spanned yarns or rovings 21, which the gripper 10 has pulled out by the method in its intermediate position. This can be assisted by actively powered unwinding. The intermediate position is close to the outer contour of the molds or near the later position of the outer contour when the molds are brought into their draping position. Binder material 18, for example in the form of binder threads or binder webs, can also be stretched by the gripper together with the yarns or rovings. There may also be an upper and a lower row of unwind stations, as shown, so that the binder material is stretched between the upper and lower groups of yarns or rovings. When pulling out, the binder material can be preactivated in the area of the yarn transfer points 14, in particular by a heating device, so that the yarns or rovings are already somewhat fixed to one another at the beginning of draping. In addition, a spreading device can be provided in the area of the yarn transfer points, which can be designed as a kind of comb with one or more rows of tines. This ensures that the yarns or rovings lie next to each other and do not slip laterally during draping. The spreader may also be displaceable along the yarn paths or along the gripper paths. Another possibility for a yarn tension measuring device 13 is shown.

Draping is the forming or shaping of yarns or rovings with the aid of a molding tool. Draping may be accomplished in one or more stages by moving the molding tool or dies simultaneously or sequentially into the plyed or roving ply. During draping, it is advantageous to regulate the yarn tensions, in particular to keep them constant. That is, as much yarn or roving is dispensed as is necessary for draping at the corresponding location of the forming tool. To achieve this, brake and clutch devices can be provided. Preferably, each unwinding station or each group of unwinding stations is assigned a corresponding control. This prevents the yarns or rovings from being overloaded or loosely laid. The yarn tensions can also be measured by suitable measuring devices in the area of the yarn transfer points and / or between the unwinding stations and the yarn transfer points. The value of the yarn tensions is preferably between 1 and 50 N / m ² .

In Figs. 3 a and 3 b, the state after the first draping is shown. From the lift table 17, the first mold 15 'was moved to the draping position. As a result, the yarns or rovings 22 are deflected and draped over the forming tool 15 '. The gripper 10 fixes the beginnings of the yarns near the outer contour of the molding tool 15 '. After this step, binder material or rovings can alternatively or additionally be applied or sprayed onto the yarns or rovings. In the next step, the yarns or rovings are further draped using the second die 16 'that has been moved to its draping position (FIGS. 4 a and 4 b). Through the interaction of the two forming tools, between which the layer of yarns or rovings is located, is a precise shaping possible. The molds can also be pressed together and one, preferably the second, or both molds can be heated, so that the binder material is activated and the yarns or rovings are dimensionally stable fixed to a layer. Simultaneously with or after fixing the yarns or rovings are separated on both sides of the molds, ie between gripper and mold and between yarn transfer points and mold. In an embodiment, the separator may be connected to the first or second mold. It is advantageous if the separation takes place at least on the side of the yarn transfer points close to the mold. As a result, there is little waste of expensive fiber material and less reworking of the fiber preform is necessary.

The separated yarns or rovings 23 can be withdrawn and wound up again by means of a rewinding device or temporarily stored by appropriate yarn guidance. The rewinding takes place in such a way that again starts of the yarns or rovings in the area of the yarn transfer points 14 come to lie so that they can be picked up by the grippers without too much waste material being produced. Sensors can be used to record the beginnings.

In Fig. 5a and 5b, the yarns or rovings have already been rewound or cut at the yarn transfer point, so that there are beginnings at the yarn transfer points. On the grippers, only a small amount of waste 24 is produced on fiber material, since they were positioned in each case close to and along the outer contour of the molding tools and have only set up as much yarn as was needed. The molds 15, 16 are returned to their lowered position. On the first mold, the first molded layer 25 remains.

Fig. 6 a and 6 b show the first and second mold 15, 16 in a rotated position. Here they were turned 90 °. But it is also another angle of rotation, for example, about 30 °, 45 °, 60 °, or a tilt possible. Preferably, the Rotation angle between 10 and 170 °. This depends on how and with which fiber orientation the further layer of yarns or rovings is to be applied. The required grippers 6 'are in the picking position to grip the beginnings 20 of the used yarns or rovings.

Then, the yarns or rovings of the further layer are stretched to an intermediate position of the grippers and draped by moving the first and second dies 15 ', 16' to the draping position. Figures 7a and 7b show the device after the yarns or rovings have been severed. The use of grippers 1 1 are in an intermediate position. For non-rectangular molds or other angles of rotation, the grippers 1 1 can also stand on various intermediate positions. The further layer of yarns or rovings and possibly of binder material can also be fixed dimensionally stable by heating and / or pressing and connected to the first layer. Together they form the fiber preform ling 28.

In Fig. 8 a, a further embodiment is shown, as for example in the production of fiber preform lingen for hoods can be used. The used grippers 10.1 are at an intermediate position, the unnecessary grippers 5.1 are in the maximum position 8.1. On the first mold 15.1, a first layer of yarns or rovings is draped and fixed. The second mold is not shown. The stocking of the yarns or rovings takes place in the unwinding stations 1 .1, 2.1. Furthermore, a binder material supply 19.1 and the yarn transfer points 14.1 are present.

The application of one or more further layers can take place in the same device or in one or more further devices according to the invention, to which the first molding tool is transferred together with the first layer. In Fig. 8b, another layer 26.1 is draped onto the rotated forming tool. For the sake of clarity, only a few yarns or rovings are shown. The used grippers 1 1 .1 are along the outer contour of the mold and make it as accurate as possible. Narrower or different width grippers can be used for even more precise adjustment.

Fig. 8 c shows how yet another layer was applied. The used grippers 12.1 are again along the outer contour. After fixing the layers together form the Faservorform ling 28.1.

LIST OF REFERENCE NUMBERS

I, 1 .1, 2, 2.1 rows of unwinding stations

3, 3 ', 4, 4' unwinding stations in use

5, 5.1 series of grippers

6, 6 'gripper in pick-up position

7, 7.1, 7 ', 7.1' guide device for grippers

8, 8.1 Location of maximum positions

9, 9.1 Location of pick-up positions

10, 10.1, 1 1,} Grippers in intermediate positions

I I .1, 12, 12.1

13, 13 'Measuring device for yarn tension

14, 14.1 Yarn transfer points

(optionally also with spreader and / or with device for binder pre-activation)

15 first mold in down position

15 ', 15.1 first mold in draping position

16 second mold in down position

16 'second mold in draping position

17 lift table

18 binder material

19, 19.1 Binder material supply

20, 20 'Beginnings of yarns or rovings

21 tense yarns or rovings

22 draped yarns or rovings

23, 23 'separated yarns or rovings

24 waste

25 first layer of yarns or rovings

26.1, 27.1 further layer of yarns or rovings

28, 28.1 Fiber preform

b Clamping width of a gripper

Β Overall clamping width of all grippers

Claims

claims

1 . Apparatus for the production of fiber preforms (28, 28.1), which in particular constitute a precursor in the production of fiber-reinforced plastic components, wherein the apparatus has a plurality of unwinding stations (1, 1, 1, 2, 2.1, 3, 3 ', 4, 4 ') for providing a plurality of yarns or rovings and a plurality of grippers (5, 5.1), each of which can grip one or more yarns or rovings at its beginning, and at least one first forming tool (15, 15', 15.1), each gripper (5, 5.1) can be moved back and forth on a path between a maximum position (8, 8.1) and a pick-up position (9, 9.1), and wherein the pick-up position (9, 9.1) is provided at a yarn transfer point (14, 14.1) and closer to the unwind station (1, 1 .1, 2, 2.1, 3, 3 ', 4, 4') than the maximum position (8, 8.1)

characterized,

in that one or more rewinding devices are provided, with which yarns or rovings (23, 23 ') which have been dispensed into the area between the yarn transfer points and the first molding tool can be at least partially withdrawn into the area between yarn transfer points (14, 14.1) and unwinding stations ( 1, 1 .1, 2, 2.1, 3, 3 ', 4, 4') and / or at the unwinding stations (1, 1 .1, 2, 2.1, 3, 3 ', 4, 4') can be wound up ,

2. Apparatus according to claim 1

characterized,

in that each gripper (5, 5.1) has its own maximum position (8, 8.1) and is assigned to its own yarn transfer point (14, 14.1) and that the grippers (5, 5.1) can each be moved individually on essentially parallel paths.

3. Device according to claim 1 or 2

characterized,

that the grippers (10, 10.1, 1 1, 1 1 .1, 12, 12.1) can take various individual intermediate positions in their path and that they can hold the respective beginnings of the yarns or rovings at these intermediate positions.

4. Device according to one of the preceding claims

characterized,

the individual grippers (5, 5.1) can each be moved on a substantially linear path from the pick-up position (9, 9.1) to the maximum position (8, 8.1).

5. Device according to one of the preceding claims

characterized,

at least 5 grippers (5, 5.1), preferably at least 10 grippers (5, 5.1), more preferably at least 20 grippers (5, 5.1) are present.

6. Device according to one of the preceding claims

characterized,

in that the first and / or a second forming tool (15, 15 ', 15.1, 16, 16') is arranged between the yarn transfer points (14, 14.1) and at least some of the grippers (10, 10.1, 11, 11, 12, 12). 12.1) can be brought, in particular so that thereby the yarns or rovings (22) are draped over the mold.

7. Device according to one of the preceding claims

characterized,

a separating device which separates the yarns or rovings between the first and / or a second shaping tool (15, 15 ', 15.1, 16, 16') and the grippers (10, 10.1, 11, 11, 12, 12.1 ), and / or a separating device which can separate the yarns or rovings between the first and / or a second forming tool (15, 15 ', 15.1, 16, 16') and the yarn transfer points (14, 14.1) ,

8. Device according to one of the preceding claims

characterized,

a separation device is provided which is suitable for separating the yarns or rovings close to an outer contour of the first and / or a second molding tool (15, 15 ', 15.1, 16, 16'), in particular closer to the molding tool (15, 15 ', 15.1, 16, 16') than at the yarn transfer points (14, 14.1).

9. Device according to one of the preceding claims

characterized,

in that each rewinding device, in particular each unwinding station (1, 1, 1, 2, 2.1, 3, 3 ', 4, 4') or each group of unwinding stations (1, 1, 1, 2, 2.1, 3, 3 ', 4 , 4 '), is assigned its own coupling and / or braking device, which are preferably designed so that each rewinding device, in particular each unwinding station or each group of unwinding stations, can retract different lengths of yarn or rovings.

10. Device according to one of the preceding claims

characterized,

that one or more sensors are provided which can detect the positions of the beginnings of the yarns or rovings in the area of the yarn transfer points (14, 14.1).

1 1. Device according to one of the preceding claims

characterized,

in that one or more spreading devices are provided in the region of the yarn transfer points (14, 14.1), in particular as a kind of comb with one or more rows of prongs.

12. A process for the production of fiber preforms (28, 28.1), which for example represent a precursor in the production of fiber-reinforced plastic components, in particular using a device according to one of the preceding claims, which comprises the following process steps in succession:

- tensioning of yarns or rovings by means of several grippers (5, 5.1)

Draping the yarns or rovings via a first forming tool (15, 15 ', 15.1)

- Separating the yarns or rovings

characterized,

that after separation, the yarns or rovings (23, 23 ') which have been dispensed into the area between the yarn transfer points and the first mold are at least partially retracted into the area between Garnübergabestellen (14, 14.1) and unwinding stations (1, 1 .1, 2, 2.1, 3, 3 ', 4, 4') and / or at the unwinding stations (1, 1 .1, 2, 2.1, 3, 3 ' , 4, 4 ') are wound up.

13. The method according to claim 12

characterized,

that after and / or during draping the yarns or rovings are fixed in a dimensionally stable manner, in particular by activation of binder material (18), and preferably by heating and / or pressing.

14. The method according to claim 12 or 13

characterized,

that when separating the yarns or rovings are close and along an outer contour of the first or a second mold (15, 15 ', 15.1, 16, 16') separated.

15. The method according to any one of claims 12 to 14

characterized,

that the positions of the beginnings of the yarns or rovings in the region of the yarn transfer points (14, 14.1) are detected with one or more sensors.