DE102013008697A1 - Method for producing multi-dimensional profiled preform from fiber semi-finished product, involves applying product on surface of application element with application stamper, when product is tensioned by clamping elements - Google Patents

Abstract

The method involves clamping a fiber semi-finished product (3) into multiple clamping elements (15a-15e,15a'-15e') along a circumference (19) of the product. The displacement of the clamping elements in a vertical direction is carried out along a horizontal plane of the product. The product is applied partially on an application surface (11) of an application element (9) with an application stamper, when the product is tensioned by the clamping elements. An independent claim is included for a device for manufacturing a preform from a fiber semi-finished product.

Description

The invention relates to a method for producing a preform from a semi-finished fiber product according to claim 1 and to an apparatus for producing a preform from a semi-finished fiber product according to claim 6.

Methods and devices of the type mentioned are known. In particular, in the automotive industry increasingly components made of fiber-reinforced plastic are used as body parts, which are both lightweight and very durable. In order to produce such a component, first at least one layer of fiber material is produced as a scrim, fabric, knitted fabric or in another suitable manner as a textile semifinished product, which is provided with a binder. The textile semifinished product is cut to size and then converted or draped in a forming device into a preform. The binder is fixed so that the preform holds its geometry. This is followed by a thermoplastic or thermosetting consolidation, wherein the fiber-reinforced plastic part is formed from the preform by resin infusion and curing. When draping the semifinished fiber product, wrinkling may occur, which may ultimately lead to failure of a component made from the preform. It is therefore essential to pay attention to minimizing wrinkles and / or elimination of wrinkles when draping the semifinished fiber product. Typically, the semifinished fiber product is clamped along its circumference in a tenter and stored by means of the tenter on a surface of a drapery body. Then it is pressed by a draping tool to the surface or draped on this. It is possible that the clamping frame comprises a plurality of clamping elements, which optionally exert locally variable clamping forces on the semifinished fiber product. It is also possible that clamping directions can be varied by the clamping elements. However, the clamping elements are fixed in a plane defined by the clamping frame. When creating the semifinished fiber product to the surface of the draping of the clamping frame can be moved only in the whole in one direction, which is perpendicular to the flat semi-finished fiber or on the plane defined by the clamping frame level. It turns out that no detailed, contour near installation of the semifinished fiber can be effected on a multi-dimensionally profiled topography of the surface, but that in particular in the area between edges of the surface only an approximate investment, in particular under connection of the edges by the shortest route results. Especially in such areas a relatively large material intake is then required during draping, or there is a relatively large Umformweg when the semifinished fiber is draped by the Drapierwerkzeugs konturnah on the drapery. A high risk of local wrinkling in such areas is the result.

The invention is therefore based on the object to provide a method and an apparatus which do not have the disadvantages mentioned. In particular, it should be possible by means of the method and the device to deposit a semi-finished fiber contour close to the surface of a drapery, so that minimal forming paths, a locally minimal material intake and thus ultimately a low risk of wrinkling results.

The object is achieved by providing a method with the steps of claim 1. As part of the process, the semifinished fiber product is clamped in a plurality of clamping elements arranged along its circumference. The semi-finished fiber defines a horizontal plane. Subsequently, at least one clamping element is displaced in the vertical direction, and the semifinished fiber product is at least partially applied to a surface of a draping body by means of the at least one displaced tensioning element. The semifinished fiber product is draped at least locally on the surface of the draping body by means of a draping die while it is being tensioned by the tensioning elements. Characterized in that at least one clamping element is displaced in the vertical direction, the semifinished fiber can be locally contoured applied to the surface of the drape body. It is thus possible to realize on the entire surface of the draping body a contour near installation of the semifinished fiber product and thus minimal forming paths and minimum material feeds for the semifinished fiber product. This minimizes the risk of wrinkling.

The at least one tensioning element is preferably displaced in the vertical direction independently of a position or displacement of all other tensioning elements. Unlike a conventional clamping frame so the individual clamping elements are not set in a predetermined plane relative to each other, but it is possible to move them independently vertically and thus the semi-finished locally defined to conform to the contour of the surface of the draping body.

In this context, the term "horizontal direction" should generally be understood as meaning a direction which lies in a plane defined by the semifinished fiber product prior to application to the surface of the drapery body. The term "vertical direction" should generally be understood to mean a direction which is perpendicular to this plane and in particular corresponds to a direction of displacement of the semifinished fiber product towards the surface of the draping body.

A method is preferred which is characterized in that the clamping elements are displaced locally, at least in part, by different distances in the vertical direction, with the semifinished fiber product fitting close to the surface of the draping body. The displacement distances for the individual clamping elements are locally determined so that they virtually follow the contour of the surface of the draping body, so that the semi-finished fiber in the region of each clamping element with a maximum contact surface or a maximum number of contact points to the surface applies. The semifinished fiber product is therefore not, as is known in conventional tenter, globally slipped over the draping body, but rather accurately applied to this.

A method is also preferred which is characterized in that a multiplicity of locally differently formed draping dies are sequentially displaced in order to drape the semifinished fiber product onto the surface. In particular, the draping is carried out in various, successive forming steps, with different draping dies being displaced one after the other so that the semifinished fiber product is draped sequentially in different areas onto the surface of the drapery body. In this case, a determination of a draping strategy suitable for a specific draping task comprises, in particular, the selection of the number, shape and effective direction of the individual draping dies as well as the determination of the sequence in which the individual draping dies are displaced.

Preferably, a displacement of the clamping elements is adjusted to the displacement of the Drapierstempel time and with respect to the displacement distances. This means in particular that the displacement of the clamping elements is synchronized with the displacement of the Drapierstempel. In particular, it is possible for the semi-finished fiber product to be applied to the local geometry of the surface of the drape body before each forming step with maximum contact, in the region of which a shaping or draping takes place in the following forming step. In this way, the forming paths and material feeds of the semi-finished fiber are minimized locally, so that the risk of wrinkling is significantly reduced. Ultimately, the method is preferably as a sequence of displacements of different clamping elements and different Drapierstempel, preferably preferably first locally the clamping elements are displaced, and then the Drapierstempel be moved to drape the semi-finished fiber locally. This procedure is repeated until the semifinished fiber product is completely draped on the surface of the drape body.

In a preferred embodiment of the method, it is also possible that at least one tensioning element is displaced while at least one draping punch is displaced. This makes it possible to locally influence stresses in the semifinished fiber product during draping, in order to avoid wrinkling or eliminate wrinkles that arise. In particular, it is possible that the clamping elements follow the local forming movements during the deformation of the semifinished fiber product. In this case, the tension in the semi-finished fiber can be kept constant or varied. It is thus possible to ensure a targeted local tracking of the semifinished fiber product during draping.

Finally, a method is preferred which is characterized in that a semi-finished fiber product is used which comprises at least two fiber layers. Different fiber layers of the semi-finished fiber are clamped in different clamping elements. The method is therefore not only for single-layer semi-finished fiber products, but also for multi-layer semifinished fiber products feasible, preferably the various fiber layers of a multi-layer fiber semi-finished different clamping elements are assigned, so that the individual fiber layers can be manipulated independently of each other using their respective associated clamping elements. In particular, it is possible to apply the different fiber layers in different ways or at different times to the surface of the draping body by means of their associated clamping elements.

The object is also achieved by providing an apparatus for producing a preform from a semi-finished fiber product having the features of claim 6. In this case, the device is in particular designed for carrying out a method according to one of claims 1 to 5. The device comprises a clamping device which comprises a plurality of at least partially independently vertically displaceable clamping elements for clamping a semi-finished fiber product. It also includes a draping body having a surface having a geometry to be formed on the preform. There is provided a plurality of draping punches displaceable in the direction of the surface of the drape body, each having a draping surface complementary to the surface. With the help of the Drapierstempel it is thus possible to drape the semi-finished fiber locally to the surface of the drape body. If the draping punches are to be displaced maximally to the surface of the draping body, a cavity is formed between the surface and the locally complementarily formed draping surface, in which the semi-finished fiber product is arranged and shaped.

The clamping elements are at least partially, preferably all, independently of each other vertically displaceable. Unlike a conventional clamping frame, they are thus not only displaceable together in a predetermined by the clamping frame level to put the semi-finished fiber over the surface of the drape body, but they can rather be displaced relative to each other, so that the semi-finished fiber contour deposited on the surface, in particular can be nestled on this. This results in locally minimal forming paths, a minimal material feed and thus an extremely low risk of wrinkling during draping.

In one embodiment of the device it is provided that the draping body is part of a lower tool. Alternatively, it is possible that the Drapierkörper itself is designed as a lower tool.

Also preferred is a device in which the draping punches are formed as tool segments of an upper tool. The device preferably comprises a total of a lower tool and an upper tool, which are displaceable relative to each other to close a cavity in which the semi-finished fiber is formed. Particularly preferably, the upper tool is designed to be displaceable, while the lower tool is designed to be fixed in space. If the upper tool has a segmented design, that is to say it has a plurality of tool segments in the form of draping punches, a displacement angle for each draping punch or each tool segment is preferably adjustable independently of the other tool segments or draping punches. For this purpose, the draping punches are preferably pivotably mounted about an axis perpendicular to the direction of displacement. Furthermore, the individual tool segments or draping punches are preferably displaceable independently of one another in the direction predetermined by the displacement angle. This makes it possible to shift the various tool segments in any direction and sequence adapted to the specific draping task, thus sequentially closing the cavity between the upper tool and the lower tool and sequentially draping the semifinished fiber product onto the lower tool. Accordingly, the clamping elements are at least partially independently and sequentially vertically displaceable, with a shift of the various clamping elements is tuned to the displacement of the various Drapierstempel time and with respect to the displacement distances.

A device is preferred in which at least one of the clamping elements has a clamping jaw, in which the semifinished fiber product can be clamped at the edge on its circumference. Preferably, all the clamping elements each have such a clamping jaw, so that the semi-finished fiber product is peripherally clamped along its circumference by the clamping jaws. It is possible that along the circumference of the semi-finished fiber clamping elements are provided with jaws having different clamping widths. By a specific choice of the different clamping widths and their arrangement along the circumference of the semifinished fiber product, the exact system of the same can be further improved on the surface of the draping body. The clamping width of the jaws responds to their extension in the direction of a circumferential line of the semifinished fiber product.

In a preferred embodiment of the device is provided that the clamping elements are arranged with respect to their position along the circumferential line of the semifinished fiber product displaced on the device. This makes it possible, points of attack of the clamping elements in which clamping forces are introduced into the semifinished fiber, as needed and tailored to the specific Drapieraufgabe to vary.

Finally, a device is preferred, which is characterized in that at least one clamping element has a displacement device. By means of the displacement device, the vertical displacement of the clamping element is effected. The displacement device is preferably designed as a linear drive. Particularly preferably, the displacement device is designed as an electric linear drive, as a pneumatic cylinder or as a hydraulic cylinder. In a preferred embodiment of the device, each clamping element has a corresponding displacement device. In this case, the displacement devices are preferably independently controllable.

The description of the method on the one hand and the device on the other hand are to be understood as complementary to each other. In particular, features that have been explicitly or implicitly described in connection with the method, preferably individually or in combination with each other, also features of a preferred embodiment of the device. Conversely, method steps which have been described explicitly or implicitly in connection with the apparatus are preferably also individually or in combination with one another also method steps of a preferred embodiment of the method.

The invention will be explained in more detail below with reference to the drawing.

Showing:

1 a schematic representation of the use of a clamping frame according to the prior art;

2 a detailed view of an embodiment of the device, and

3 a schematic representation of an embodiment of the method.

1 shows a schematic representation of a known from the prior art approach using a device 1 for producing a preform from a semi-finished fiber product 3 , wherein the device 1 a clamping device 5 which has a tenter 7 includes. In the tenter frame 7 is the semifinished fiber product 3 clamped, with the tenter 7 extending in one plane. The semifinished fiber product 3 and the tenter 7 define a horizontal plane. The clamping frame 7 includes in 1 not shown clamping elements, which typically have jaws, with which the semi-finished fiber 3 clamped along its circumference and thus held or in the tenter 7 is fixed. Optionally, in terms of their amount and preferably also their direction variable clamping forces in the semifinished fiber product 3 by means of the clamping elements can be introduced. However, these forces are due to the tenter frame 7 on the one hand and the semi-finished fiber product 3 on the other hand defined level limited.

In 1 at the top of a) is the tenter frame 7 represented in a position in which the semi-finished fiber 3 not yet on a drapery body 9 is stored. To the semi-finished fiber to a surface 11 of the drapery body 9 create the tenter 7 conventionally displaced from its position shown at a) to its position shown at b) below, namely in a vertical direction which is perpendicular to the previously defined horizontal direction.

From the schematic diagram according to 1 it is obvious that the semi-finished fiber 3 not everywhere local contour right to the surface 11 can cling, because the clamping elements along the circumference of the semifinished fiber product 3 on the through the tenter 7 given level are limited. It is therefore only possible, the semi-finished fiber 3 over the drapery body 9 to evert, in particular, it has concave structures of the surface 11 is spanned and can not penetrate or follow its course. For example, arise in a first area 13 as well as in a second area 13 ' considerable distances between the semifinished fiber product 3 and the surface 11 so that here ultimately a relatively large Umformweg by draping the semi-finished fiber 3 must be covered, which also results in a relatively large material intake. This consists especially in the areas 13 . 13 ' the risk of wrinkling and ultimately component failure with respect to a component made from the preform.

2 shows a detailed representation of an embodiment of the device 1 , Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. The device has a clamping device 5 on, but no tenter 7 more is provided. Rather, the clamping device comprises 5 a plurality of independently vertical, namely in the direction of in 2 shown double arrows P displaceable clamping elements, of which two here with the reference numeral 15 are designated. As a result, the clamping elements 15 are independently displaced vertically, they do not have - in contrast to the clamping elements of the clamping frame 7 according to 1 - Be always arranged in a common plane, but rather can be arranged in different levels. This makes it possible that in the clamping device 5 clamped semi-finished fiber products 3 contour right to the surface 11 to apply.

The clamping elements 15 have jaws 17 on, in which the semi-finished fiber 3 at the edge along a circumference 19 is clamped.

Preferably, the clamping elements 15 at the device 1 along the circumference 19 At any distance from each other variably positionable. As a result, a particularly high flexibility for the contour-equitable application of semi-finished fiber 3 to the surface 11 ensured, in particular, the arrangement of the clamping elements 15 on different topographies of different surfaces 11 can be coordinated.

Alternatively or additionally, the jaws 17 preferably at least partially different widths, wherein the - in the direction of the circumference 19 measured - widths preferably on the concrete Drapieraufgabe, in particular on the concrete geometry of the surface 11 be matched.

The clamping elements 15 preferably have displacement devices 21 on, here as a cylinder 23 are formed, in which pistons 25 are taken displaced in the vertical direction. In particular, the relocation facilities 21 preferably designed as linear drives, in particular as a cylinder / piston combination. It is possible that the relocation facilities 21 are designed as electric linear drives, as a pneumatic cylinder or as a hydraulic cylinder.

The schematic diagram according to 2 shows the clamping of a single-layer semifinished fiber product 3 in the clamping device 5 , However, it is readily possible, even a multi-layer semi-finished fiber 3 in the clamping device 5 to stretch. In this case, different layers of the semifinished fiber product are preferably used 3 in different clamping elements 15 clamped so that the layers independently and separately using their respective associated clamping elements 15 can be relocated. In this way, it is also possible with a multi-layer semi-finished fiber, minimal forming paths locally on the surface 11 realize, whereby in particular a small displacement of the layers relative to each other during draping of the semifinished fiber product 3 on the surface 11 can be guaranteed. This results in a total distortion and low-deformation deformation of both single-layer and multi-layer semi-finished fiber products 3 ,

3 shows a schematic representation of an embodiment of the method. Identical and functionally identical elements are provided with the same reference numerals, so that reference is made to the preceding description. First, the semi-finished fiber 3 in the of the clamping device 5 comprised a plurality along the circumference 19 arranged clamping elements 15 clamped. In this case, preferably all clamping elements are initially 15 arranged on one level, so that the semi-finished fiber 3 defines a horizontal plane on which a vertical direction is perpendicular.

In order to be able to describe the method more clearly, it comprises 3 following simplification: The drapery body 9 is shown here as so-called 2.5D geometry, which means that the surface 11 only in one direction, namely in one direction, in the image plane of 3 runs from left to right, having a non-zero, locally different curvature. By contrast, the curvature of the draping body 9 in a direction perpendicular thereto, in the image plane of 3 runs in, constant, or it disappears identically. The drapery body points in this direction 9 a constant cross section.

According to this simplified geometry of the surface 11 Here pairs of clamping elements are provided, which face each other along the direction in which the draping body 9 has no curvature. These pairs include a first pair of tension members 15a . 15a ' , a second couple 15b . 15b ' , a third couple 15c . 15c ' , a fourth pair 15d . 15d ' and a fifth pair 15e . 15e ' , The pairs are - in the direction of the non-vanishing curvature of the surface 11 Seen - each provided at a height on which the surface 11 has a stepped from an adjacent geometry stage.

As in 3 at b) is shown, now the clamping elements 15 shifted in the vertical direction, and the semi-finished fiber 3 At first, it will be partially exposed to the surface 11 created. In this case, all clamping elements are in the process step shown here 15 been shifted, with the first pair 15a . 15a ' the clamping elements on a first - now measured in the vertical direction - height is arranged, wherein the second pair 15b . 15b ' the clamping elements is arranged at a second height, and wherein the remaining pairs of clamping elements 15c . 15c ' . 15d . 15d ' . 15e . 15e ' be arranged at a same, third height. This is the semi-finished fiber 3 in the area of the clamping elements 15a . 15a ' . 15b . 15b ' . 15c . 15c ' each local to the topography of the surface 11 contoured close. In the area of the remaining clamping element pairs 15d . 15d ' . 15e . 15e ' on the other hand, no investment has yet been made.

It is now possible that draping punches not already shown in this state, preferably designed as tool segments of an upper tool, are applied to the semifinished fiber product 3 to be relocated to this on the surface 11 to drape. The clamping elements 15 are preferably synchronized or shifted in time and with respect to their displacement distances tuned to the displacement of Drapierstempel.

In a third step, in the embodiment of the method shown here, the clamping elements 15 shifted to their final positions, so that a complete, conformal system of semi-finished fiber 3 on the surface 11 in all areas of the same results. Thereafter, the remaining, not yet displaced Drapierstempel on the surface are preferred 11 shifted to the semi-finished fiber 3 completely on the surface 11 to drape.

It turns out that in the illustrated, simplified geometry of the drape body 9 the clamping element pairs 15a . 15a ' . 15b . 15b ' . 15c . 15c ' . 15d . 15d ' . 15e . 15e ' be shifted in pairs identically. This corresponds to the topography of the surface changing only in one direction 11 , Indicates the drapery body 9 In contrast, a more complex, three-dimensional structure, which includes a non-vanishing curvature, especially in two directions, eliminates the pairwise coupling of the clamping elements 15 , Rather, then diametrically opposed clamping elements - if any are provided - independently and individually relocated, so always a locally contoured system of semi-finished fiber 3 to the surface 11 given is.

Anyway, based on 3 clearly that the semi-finished fiber 3 not, as is known in the art, by means of the tensioning device 5 just over the surface 11 of the drapery body 11 is slipped, but that by the flexible displacement of the clamping elements 15 on the entire surface 11 a locally contoured system and thus a realization of minimal forming paths, minimal bearing displacements and minimal material feeds is effected.

Overall, this shows that it is possible with the aid of the method and the device to create a multi-dimensionally profiled preform, which is deformed in three dimensions in particular, avoiding a risk of wrinkling with little shift in position, with little distortion.

Claims (10)

Process for producing a preform from a semi-finished fiber product ( 3 ), comprising the following steps: clamping the semifinished fiber product ( 3 ) in a plurality of along a circumference ( 19 ) of the semifinished fiber product ( 3 ) arranged clamping elements ( 15 ), wherein the semi-finished fiber product ( 3 ) defines a horizontal plane, displacing at least one tensioning element in the vertical direction and applying the semifinished fiber product ( 3 ) at least partially to a surface ( 11 ) of a draping body ( 9 ) using the at least one displaced clamping element ( 15 ); at least local draping of the semifinished fiber product ( 3 ) on the surface ( 11 ) of the draping body ( 9 ) with a Drapierstempel, while the semi-finished fiber ( 3 ) of the clamping elements ( 15 ) is stretched. Method according to claim 1, characterized in that the clamping elements ( 15 ) are locally displaced, at least in part, by different distances in the vertical direction, the semi-finished fiber product ( 3 ) close to the surface ( 11 ) of the draping body ( 9 ) is nestled. Method according to one of the preceding claims, characterized in that a plurality of locally differently formed Drapierstempel is sequentially displaced to the semifinished fiber product ( 3 ) on the surface ( 11 ) to drape. Method according to one of the preceding claims, characterized in that a displacement of the clamping elements ( 15 ) is adjusted to a shift of Drapierstempel time and with respect to the relocation distances. Method according to one of the preceding claims, characterized in that a semi-finished fiber product is used which comprises at least two fiber layers, wherein different fiber layers in different clamping elements ( 15 ) are clamped. Contraption ( 1 ) for producing a preform from a semi-finished fiber product ( 3 ), in particular for carrying out a method according to one of claims 1 to 5, with a tensioning device ( 5 ), which are a plurality of at least partially independently displaceable vertically displaceable clamping elements ( 15 ) for clamping the semifinished fiber product ( 3 ), a draping body ( 9 ) with a surface having a geometry to be formed on the preform ( 11 ), and with a plurality of drapery punches facing towards the surface ( 11 ) of the draping body ( 9 ) are arranged displaceably, wherein each one locally to the surface ( 11 ) have complementary draping surface. Apparatus according to claim 6, characterized in that the drapery body ( 9 ) Part of a lower tool or as a lower tool is formed. Device according to one of claims 6 and 7, characterized in that the Drapierstempel are formed as a tool segments of an upper tool, wherein preferably a displacement angle for each Drapierstempel is independent of any other Drapierstempel adjustable. Device according to one of claims 6 to 8, characterized in that at least one clamping element ( 15 ) at least one jaw ( 17 ), in which the semi-finished fiber product ( 3 ) along its periphery ( 19 ) is clamped. Device according to one of claims 6 to 9, characterized in that at least one clamping element ( 15 ) a relocation device ( 21 ), which is preferably designed as a linear drive, particularly preferably as an electric linear drive or as a pneumatic cylinder or as a hydraulic cylinder.

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