DE102014011033B4 - Process for producing a fiber composite plastic component - Google Patents

Abstract

Method for producing a fiber composite plastic component with a foam core element (1) and at least one cover layer (3) covering the foam core element (1), which is constructed from at least one semifinished fiber layer (5) impregnated with a matrix material (7) and at least one Joining element (9) for the mechanical connection of the cover layer (3) to the foam core element (1), with a first process step, in which a surface of a foam core element (1) with at least one semi-finished fiber layer (5) is loosely covered, a second process step, in which for fixing the semi-finished fiber layer (5) on the foam core element (1) the joining element (9) is driven into the loose composite, while displacing the core material of the foam core element (1), whereby the joining element (9) is in frictional connection with the core material , And a third process step, in which on the foam core element (1) fixed semi-finished fiber product (5) with a liquid The initial component of the matrix material (7) is impregnated, wherein the injection of the liquid starting component into the semifinished fiber layer (5) takes place in an RTM process in which a preform consisting of the foam core element (1) and the semi-finished fiber layer (5) mechanically bonded thereto. is constructed, in a cavity (20) of an RTM tool (21) is inserted, wherein an element head (11) of the joining element (9) for positionally correct positioning in the RTM tool (21) in abutment with the cavity (20) defining Forming surface of the RTM tool (21) is used, and wherein then with closed cavity (20) under pressure and heat, the starting component of the matrix material (7) is injected.

Description

The invention relates to a method for producing a fiber composite plastic component according to claim 1.

In automotive construction, complete vehicle structures, such as a rear wall cross member or a sill, can be produced in lightweight construction, for example as so-called sandwich components with a foam core. Such a sandwich component can be formed from an inner foam core as well as cover layers covering the foam core. Each of these cover layers may be composed of at least one semi-finished fiber layer impregnated with a matrix material. The foam core within the fiber composite plastic component acts profile-stiffening, whereby, for example, in a crash, an early buckling of the respective plastic component can be avoided.

In the production of such a sandwich component, at least one semi-finished fiber layer (alternatively also a multiplicity of such layers) is initially placed loosely on the foam core in a first process step. The semi-finished fiber layer may be preformed as a so-called sub-preform with respect to the component geometry to be produced close to final contour. In order to ensure a secure position of the still-dry semi-finished fiber layer (that is, not impregnated with matrix material), the semifinished fiber layer is glued to the foam core by means of a spray adhesive. Alternatively, a so-called binder can be applied to the foam core and the textile layer can be attached to the foam core by means of the binder.

By applying the spray adhesive or the binder, additional substances are brought into the adhesion limit. As a result, the handling of the semi-finished fiber layers is significantly more difficult. As soon as the semifinished fiber layer has been applied to the foam core, it is fixed inseparably immediately. In practice, this manifests itself in partially shifted and / or ruptured fibers. In addition, each applied semi-finished fiber layer must be bonded individually and each sub-area are sprayed in succession, which is expensive manufacturing technology. In addition, a chemically working binder would have to be heated considerably before being applied, which would result in additional expenditure of energy and time as well as greatly complicating their handling.

From the WO 2014/075198 A1 a method for producing a fiber composite plastic component is known in which initially overlapping semi-finished fiber layers are joined together by means of a joining element. For this purpose, the semi-finished fiber layers are first placed on a work surface and then a made of thermoplastic material bolt is driven into the two overlapping fiber semi-finished layers. When driving frictional heat is generated, whereby the joining element melts and its material can penetrate into the fiber structures.

From the DE 103 42 183 A1 is a force introduction point in core connections known. From the DE 10 2009 026 458 A1 For example, a structural component and a manufacturing method for such a structural component are known. From the DE 10 2008 043 314 A1 For example, a method and apparatus for reinforcing a substrate or textile of a core structure of a device is known. From the DE 10 2009 010 292 A1 a method for producing a fiber-reinforced plastic component is known. From the DE 10 2011 120 636 A1 a fiber composite component assembly is known.

The object of the invention is to provide a method for producing a fiber composite plastic component, in which a simple definition of the still-dry semi-finished fiber layer on the core element is made possible in manufacturing technology, without damaging the fiber structures.

The object is solved by the features of claim 1. Preferred embodiments of the invention are disclosed in the subclaims.

The invention is based on the problem that a cohesive connection of the semifinished fiber layer on the core element by means of a chemical binder and / or a spray adhesive during further handling until completion of the fiber composite plastic component can lead to damage and / or displacement of the fiber structures. The damage / displacement of the fiber structures is mainly due to the complex joining by means of material connection. Against this background, the fiber composite plastic part has at least one joining element, which no longer binds the semifinished fiber layer of the cover layer chemically to the core element, but rather mechanically, that is, penetrates the semifinished fiber layer of the cover layer and is driven into the core material of the core element, while displacing the Core material of the core element, whereby the joining material comes into frictional connection with the core material. Particularly preferably, in such a connection, the complete layer structure consisting, for example, of 16 to 19 semifinished fiber layer layers can be joined locally in a single joining step. The complete fixation of the at least one semi-finished fiber layer on the core element can be accomplished by a correspondingly selected number of joining elements.

Preferably, the material of the joining element may be a plastic, whereby a corrosion is prevented, which would possibly result in a material combination of metal and carbon fibers. The plastic material of the joining element is designed so that it is different material to the matrix material. In this case, it is ensured that in the subsequent RTM process when injecting the liquid starting component of the matrix material, the joining element material does not dissolve in the liquid matrix material component, but rather remains unaffected by it.

In a finished fiber composite plastic component, an upper side of the element head of the joining element can be largely uncovered by the matrix material of the fiber composite plastic component, that is, be visible to the outside. In particular, the top of the element head can go flush in the adjacent component surface.

In a particularly preferred technical realization, the joining element can not be bolt-shaped, but rather be designed in the form of a clip in profile. Accordingly, the element head may be formed as a web whose ends project to form a U-profile by means of clip legs.

It is of great importance that the fiber structure of the semi-finished fiber layer remains largely undamaged when driving the joining element. Against this background, the joining element may have a small cross-sectional area of, for example, about 1 mm ² . Accordingly, the joining element may be formed in wire-shaped in cross section, with a rectangular or circular cross-section.

The clip legs of the U-profile-shaped joining element can protrude substantially at right angles from the head-side web of the joining element, at least in the manufacturing state, that is to say in the still undeformed state. In this case, the two clip legs can be attached to the preform and driven when driving in alignment with the input direction (F).

A sufficiently large bond strength between the joining element and the semi-finished fiber layer and the core element is of great importance for the further process steps. Against this background, the two clip legs of the joining element can each have guide flanks on the outside. These can taper in a wedge shape under cross-sectional taper in the direction of the free end faces of the clip legs. In the driving described above, the displaced core material exerts a transverse force component, the guiding flanks of the clip legs. As a result, the clip legs are shifted towards each other to form undercuts.

After the driving in of the at least one joining element, the at least one semi-finished fiber layer is fixed sufficiently firmly to the core element to form a preform. Subsequently, the still-dry semi-finished fiber layer is impregnated with a liquid starting component of the matrix material in an injection process. The liquid starting component of the matrix material is injected in an RTM process in which the preform is placed in a cavity of an RTM tool. By means of the element heads of the joining elements exposed to the outside, a positionally correct positioning of the preform in the RTM tool takes place in which the element heads are brought into contact with the forming surfaces of the RTM tool defining the cavity. Subsequently, with the mold cavity closed, the still liquid starting component of the material of the material can be injected under pressure and heat into the semi-finished fiber layer.

• 1 in einer Teilschnittdarstellung ein fertiggestelltes Faserverbund-Kunststoffbauteil;
• 2 bis 6 jeweils Ansichten, die die Prozessschritte zur Herstellung des in der 1 gezeigten Faserverbund-Kunststoffbauteils veranschaulichen;
• 7 in perspektivischer Darstellung ein Fügeelement in Alleinstellung;
• 8 und 9 jeweils die Anwendung von Fügeelementen gemäß einem zweiten Ausführungsbeispiel.

Show it: -

• 1 in a partial sectional view of a finished fiber composite plastic component;
• 2 to 6 each views that illustrate the process steps involved in making the in 1 illustrate fiber composite plastic component shown;
• 7 in perspective a joining element in isolation;
• 8th and 9 in each case the application of joining elements according to a second embodiment.

In the 1 a fiber composite plastic component is roughly schematically shown, the core element as an inner foam core 1 has, its upper and lower sides each with cover layers 3 are covered. Each of the cover layers 3 is in the 1 by way of example from a semi-finished fiber layer 5 constructed with a matrix material 7 is soaked. Like from the 1 further shows, are in the plastic component joining elements 9 integrated. Each of these joining elements 9 pierces one of the cover layers 3 and is in the core material of the foam core 1 driven. Each of the joining elements 9 has an element head 11 as well as element feet 13 on. The element head 11 is according to the 1 at its top 17 from the matrix material 7 the fiber composite plastic component exposed, that is visible to the outside. In contrast, the two element feet 13 , as mentioned above, in the foam core 1 driven. The element head 11 of the respective joining element 9 is aligned flush with the adjacent component surface.

As is apparent from the figures, the joining element 9 executed in profile clip-like, the element head 11 according to 7 is formed as a web, protrude at its ends to form a U-profile clip legs, which are the above-mentioned element feet 13 define.

According to the perspective view of the 7 is the clip-like joining element 9 formed with extremely small cross-sectional area, in order to avoid damage to and / or displacement of the fiber structures when driving into the preform.

In a method for producing the in 1 shown fiber composite plastic component is according to the 2 first the foam core 1 provided. Subsequently, each semi-finished fiber layers are on the upper and lower sides 5 Loosely applied (preforms). For fixing the semi-finished fiber products 5 on the foam core 1 become at intervals to each other, the joining elements 9 in a joining direction F driven into the loose composite ( 4 ). The brace thighs 13 are in alignment with the joining direction F aligned. After the joining process are in accordance with the 5 the tops 17 the element heads 11 the joining elements 9 still exposed to the outside and flush with the surface in the semi-finished fiber layers 5 integrated, forming a preform. The preform is then according to the 6 in a cavity 20 an indicated RTM tool 21 inserted. Like from the 6 shows, are the tops 17 the element heads 11 in contact with the respective, the cavity 20 defining forming surfaces of the RTM tool 21 whereby a correct position positioning of the preform can be ensured in the RTM tool.

Subsequently, the tool cavity 20 closed and a liquid starting component of the matrix material 7 under pressure and heat into the tool cavity 20 injected.

After curing of the matrix material 7 The thus finished fiber composite plastic component from the tool cavity 20 taken.

In the 8th and 9 are shown views illustrating a second embodiment of the invention: are in the 8th the joining elements 9 designed substantially identical to the joining elements in the previous embodiment, with the exception that the clip legs 13 the joining elements 9 in the 8th and 9 on the outside each guide flanks 23 have, under cross-sectional taper wedge-shaped on the free end faces of the clip legs 13 run. When driving in the joining elements 9 In the joining direction, the displaced core material becomes a lateral force component F _Q in the lateral guide flanks 23 introduced the staple leg, causing them undercuts 25 to be shifted towards each other, as it is in the 9 is shown. In this way, the anchoring of the joining elements 9 in the foam material of the foam core 1 improved.

Claims (6)

Method for producing a fiber composite plastic component with a foam core element (1) and at least one cover layer (3) covering the foam core element (1), which is constructed from at least one semifinished fiber layer (5) impregnated with a matrix material (7) and at least one Joining element (9) for the mechanical connection of the cover layer (3) to the foam core element (1), with a first process step, in which a surface of a foam core element (1) with at least one semi-finished fiber layer (5) is loosely covered, a second process step, in which for fixing the semi-finished fiber layer (5) on the foam core element (1) the joining element (9) is driven into the loose composite, while displacing the core material of the foam core element (1), whereby the joining element (9) is in frictional connection with the core material , And a third process step, in which on the foam core element (1) fixed semi-finished fiber product (5) with a liquid The initial component of the matrix material (7) is impregnated, wherein the injection of the liquid starting component into the semifinished fiber layer (5) takes place in an RTM process in which a preform consisting of the foam core element (1) and the semi-finished fiber layer (5) mechanically bonded thereto. is constructed, in a cavity (20) of an RTM tool (21) is inserted, wherein an element head (11) of the joining element (9) for positionally correct positioning in the RTM tool (21) in abutment with the cavity (20) defining Forming surface of the RTM tool (21) is used, and wherein then with closed cavity (20) under pressure and heat, the starting component of the matrix material (7) is injected. Method according to Claim 1 , characterized in that the material of the joining element (9) is a plastic, and that in particular the plastic material is different from the matrix material (7). Method according to one of Claims 1 or 2 , characterized in that the joining element is formed in a clip-like profile, with a designed as a web element head (11) to whose ends protrude to form a U-profile clip leg (13). Method according to Claim 3 , characterized in that the joining element (9) is wire-like with a small cross-sectional area in the range of about 1 mm ^{2 is} formed. Method according to Claim 3 or 4 , characterized in that the clip legs (13) protrude at least in the manufacturing state, that is in the undeformed state substantially at right angles to the head-side web (11) of the joining element (9), and / or that the clip legs (13) during Driving in alignment with the input direction (F) on the preform (19) can be attached. Method according to one of Claims 3 to 5 , characterized in that the clip legs (13) of the joining element (9) on the outside guide flanks (23) which run under cross-sectional taper wedge-shaped on the free end faces of the clip legs (13), and in particular that displaced during driving core material a lateral force component (F _Q ) exerts on the guide flanks (23) of the clip legs (13) and the clip legs (13) are displaceable toward one another to form undercuts (25).

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