DE102011120986A1 - Injection molding method for manufacturing fiber composite hollow profile component in automobile industry, involves demolding hollow profile with functional structures, heating core while melting out core material of hollow profile - Google Patents

Abstract

The method involves wrapping a core (1) with an impregnated fiber material (2), and inserting the wrapped core into an injection mold (11). The wrapped core is heated, and a thermosetting matrix material is initially cured and fixed with the fiber material to obtain a core-filled hollow profile (3). Molded- and/or functional structures of the thermoplastic material are injection molded to the profile in the mold. The profile is demolded with the functional structures. The core is heated according to certain melting temperature while melting out the core material of the profile. The fiber material is tapes or bands of reinforcing fibers, which are selected from a group consisting of mineral fibers, glass fibers, carbon fibers, polymer fibers, aramid fibers or natural fibers. An independent claim is also included for a fiber composite hollow profile component.

Description

The invention relates to an injection molding process for producing a fiber composite hollow profile component and the component itself.

With regard to the production of fiber composite hollow profile components, a large number of production methods are already known using cores which are removed therefrom after the hollow profile has been produced.

The DE 10 2007 026 453 A1 describes, for example, a method for producing a multi-cell composite structure with cartwheel profile for axles and shafts and with fiber-reinforced belts and shear webs. The composite structure is fabricated in the Resin Transfer Molding (RTM) process by means of a closed tooling system that dictates the outer contour of the composite structure. The method provides to form the cells of the hollow structure by reusable mandrels of aluminum or steel or lost washable mandrels, wherein first the cellular webs are constructed by winding a plurality of braided tubes of reinforcing fibers on the mandrels, and wherein fiber ribbons with unidirectional, longitudinal fiber orientation be integrated as a semi-finished for the straps, or the mandrels are surrounded by winding technology with reinforcing fibers. Then the forming cores enveloped with fibers are assembled with positioning aids and then the complete fiber preform is inserted with mold cores for infiltration with reaction resin in a closed vacuum-tight mold. Now, the enclosed air in the tool is evacuated and injected reaction resin, then fed heat and finally is removed from the mold.

DE 10 2010 013 131 A1 also relates to a molded part which can be produced with cavity: There is an expansion body in the preform which pressurizes a process for the production of continuous fiber reinforced thermoplastic molded parts, wherein initially flat, unidirectional fiber reinforced mats with a surrounding the fibers at least partially thermoplastic matrix are provided, the mats are transferred to a rough contour of the molding predetermining workpiece carrier and stored on the workpiece carrier to a three-dimensional preform and continuously built so that the fiber orientation of the mats on the later use of the molding forces acting, and the inside thereof of the molding resulting load paths, is tuned. After fixing the mats to each other during or after completion of the preform assembly, the preform is heated to or above the melting temperature of the thermoplastic matrix of the preform, which is placed in a mold forming the final contour of the molding. In order to ensure the consolidation of the preform while maintaining the fiber orientation within the preform, a homogeneous mold internal pressure is set. Finally, the consolidated molding, to which optionally a piping made of fiber-reinforced plastic is injected, are removed from the mold. For the manufacture of a cavity shaped article, an expansion body is placed in the preform which is pressurized to form the cavity in communication with the walls of the mold.

Based on this prior art, it is an object of the present invention to allow the production of a fiber composite hollow profile component with injection-molded and or functional structures, without collapsing the molded profile and / or functional structures in the hollow profile.

This object is achieved by a method having the features of claim 1. Further developments of the method are set forth in the subclaims.

Furthermore, there is the task of creating an improved in terms of its robust fiber composite hollow profile component.

This object is achieved by the fiber composite hollow profile component with the features of claim 7.

A first embodiment of the method relates to an injection molding method for producing a fiber composite hollow profile component with molded molding and / or functional structures of a thermoplastic material.

• a) Gießen eines Kerns in einem ersten Werkzeug mit einer Form, die der des Hohlprofils entspricht,
• b) Tränken eines Fasermaterials mit einem schnellhärtenden duroplastischen Matrixmaterial,
• c) Umwickeln des Kerns mit dem getränkten Fasermaterial,
• d) Einlegen des umwickelten Kerns in ein zweites Spritzgusswerkzeug und Beaufschlagen mit Wärme. Hierbei kommt es zumindest zum An- oder sogar zum Aushärten des duroplastischen Matrixmaterials und dadurch Fixieren des Fasermaterials. Dabei wird das mit dem Kern gefüllte Hohlprofil erhalten. Nun folgt in Schritt
• e) Spritzgießen der Form- und/oder Funktionsstrukturen aus dem thermoplastischen Kunststoff an das kerngefüllte Hohlprofil, wobei das Spritzgießen in dem selben oder einem anderen Spritzgusswerkzeug erfolgt wie Schritt d),
• f) Entformen des kerngefüllten Hohlprofils mit den angespritzten Form- und/oder Funktionsstrukturen und
• g) Erwärmen des Kerns auf zumindest die Schmelztemperatur des Kerns und dabei Ausschmelzen des Kernmaterials aus dem Hohlprofil.

The method comprises the steps

• a) casting a core in a first tool having a shape corresponding to that of the hollow profile,
• b) impregnating a fiber material with a fast-curing thermosetting matrix material,
• c) wrapping the core with the impregnated fiber material,
• d) placing the wrapped core in a second injection mold and applying heat. In this case, at least the curing or even hardening of the thermosetting matrix material takes place, thereby fixing the fiber material. In this case, the filled with the core hollow profile is obtained. Now follow in step
• e) injection molding of the molding and / or functional structures of the thermoplastic material to the core-filled hollow profile, wherein the Injection molding in the same or a different injection molding tool takes place as step d),
• f) demolding the core-filled hollow profile with the molded molding and / or functional structures and
• g) heating the core to at least the melting temperature of the core and thereby melting out the core material from the hollow profile.

A thermosetting matrix material is to be understood as meaning the precursors, in particular resins, from which the duroplastic matrix of the fiber-reinforced plastic (FRP) is formed by chemical hardening.

By the present inventive method of large-scale technical use of endlessly reinforced fiber plastic profiles with subsequent functional integration is made possible by injection molding. The present invention makes it possible to replace conventional metallic hollow profiles with significantly lighter FRP profiles, in particular GRP or CFRP profiles. Hollow profiles can be realized, for example, by means of the winding method by means of the core remelting method, wherein the core located during processing in the hollow profile advantageously supports the profile in the connected injection molding and prevents collapse due to the high injection pressure. Hollow profiles obtained in this way can be used as structural parts, for example as cross members under the dashboard, but also as front end supports, etc., and thus replace the heavier parts that are currently being carried out, for example, in hydroforming injection molding technology.

Optionally, the hollow profile can be cleaned in a further step according to the invention.

Advantageously, the core is made of a metal or metal alloy with a low melting point, preferably below 300 ° C. Suitable materials are Sn and / or Bi alloys whose melting point or their melting temperature is lower than the melting temperature of the thermoplastic molding resin used and the decomposition temperature of the thermosetting matrix plastic; the latter temperatures are the limiting parameters with respect to the melting point of the metal or metal alloy.

For the injection molding method in an embodiment of the present invention, as the fiber material, fibers, bundles, rovings, tapes / ribbons of reinforcing fibers composed of mineral fibers, glass fibers, carbon fibers, polymer fibers, aramid fibers, natural fibers or combinations thereof may be used.

Another advantageous aspect relates to the core, which can be configured with a complex geometry having undercuts or openings.

Incidentally, in step c), the fiber material can be wound in multiple layers onto the core; this happens in particular power flow oriented.

The heating of the core to at least the melting temperature of the core in step d) can be carried out by the preheated injection molding tool.

Furthermore, according to the invention, the duroplastic matrix material and the thermoplastic thermoplastic are adapted to one another with regard to their adhesion properties; Moreover, in order to provide an alternative which effects the adhesion, care can be taken even during the casting of the core and / or during the winding of the fiber material that positive locking elements such as undercuts or passages on the hollow profile are expedient for the adhesion of the molded and / or molded parts Function structures are generated.

Advantageously, after step g), the core material removed from the hollow profile can be picked up and returned to the process step a) in order to cast another core. Thus, the method according to the invention is also advantageous from the aspect of sustainability.

A fiber composite hollow profile component produced in this way with injection-molded and / or functional structures is suitable for use as a motor vehicle component; in particular, it is very robust and dimensionally stable due to the combination of the thermoset matrix winding and the molded and / or functional structures made of thermoplastic material arranged above or thereon.

These and other advantages will be set forth by the following description with reference to the accompanying figure.

The reference to the figure in the description is to aid in the description and understanding of the subject matter. Articles or parts of objects which are substantially the same or similar may be given the same reference numerals. The figure is merely a schematic representation of an embodiment of the invention.

It shows 1 a process flow diagram of the process.

Here, first, see step a), in a separate tool 10 a core 1 cast, which for the purpose of later melting out of an alloy with a low melting point, that is advantageously below 300 ° C, consists. Suitable are tin or bismuth with melting points of 231.93 ° C and 271.3 ° C, respectively. The geometry of the core 1 is on the resulting hollow profile 4 , see step h), with an enormous variety of shapes and geometries is possible, which also undercuts and breakthroughs, available about about slider of the form 10 , may have.

The cast core 1 comes with a winding 2 provided with a fast-curing thermosetting matrix. For this purpose, fibers are used in step b) 2 , or even tapes, through an impregnating bath 12 guided.

The winding process allows versatile layer structures to be realized. Following (step d) is the impregnated winding 2 provided core 1 in a preheated injection mold 11 given and subjected to a temperature treatment. Due to the temperature influence of the injection molding tool 11 begins the crosslinking of the thermoset matrix. As a result of curing, the fibers become 2 fixed and the "" is preserved.

After the curing or hardening of the thermoset matrix, the injection molding process in step e) is followed by thermoplastic material, which is also present in the tool 11 can be executed. This forms and functional elements 5 to the hollow profile 3 that still with the core 1 filled, attached. In this case, a connection is achieved between the thermoset of the impregnating matrix and the molded thermoplastic. The adhesion between the thermosetting plastic and thermoplastic takes place via a suitable choice of plastic partners (thermoset and thermoplastic) and / or via positive connections such as undercuts or injection points.

Now (step f) the core-feeling hollow profile 3 demolded and the core 1 by heat input, such as by heat (step g) by means of the IR radiator 13 , or alternatively a furnace, or other heat generating device are melted out. It becomes the hollow profile 4 receive.

The core material is collected in the drip tray 5 and can be advantageously recycled economically in the process.

Finally, this is now the core 1 freed hollow profile 4 cleaned and ready for use; Step h).

Through this combination of the indicated production technologies, the production of FRP hollow profiles without a remaining core is advantageously possible, so that these components are lighter than corresponding components with a core. Furthermore, the combination of the thermoset with a thermoplastic results in a robust component.

In the process, the use of the core achieves improved handling and easier loading of the injection molding machine than if only one impregnated semi-finished product is used.

Furthermore, due to the matrix hardening out in the tool, a fixation of the layer structure results, which prevents disadvantageous changes in the winding during the subsequent injection molding process, such as layer displacements caused by the injection pressure. Thus, just by the fiber fixing the application of the injection molding process is possible, which in turn allows a functional integration that is difficult to obtain in purely thermosetting processing.

Finally, a composite adhesion is made possible by special core geometries, such as injection points or undercuts, and it is possible to produce components which can substitute metal hybrid components in motor vehicle construction, which is particularly favorable due to the weight saving thus achieved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007026453 A1 [0003]
• DE 102010013131 A1 [0004]

Claims (10)

Injection molding process for producing a fiber composite hollow profile component ( 5 ) with injection molded and / or functional structures ( 6 ) of a thermoplastic material, comprising the steps of a) casting a core ( 1 ) in a first tool ( 10 ) with a hollow profile ( 5 ) corresponding form, b) impregnating a fiber material ( 2 ) with a fast-curing thermosetting matrix material, c) wrapping the core ( 1 ) with the impregnated fiber material ( 2 ), d) inserting the wrapped core ( 1 ) in a second injection molding tool ( 11 ) and applying heat, thereby at least hardening of the thermosetting matrix material and thereby fixing the fiber material ( 2 ), while maintaining the core-filled hollow profile ( 3 ), e) injection molding of the mold and / or functional structures ( 6 ) of the thermoplastic material to the core-filled hollow profile ( 3 ) in an injection molding tool ( 11 ), f) demolding the core-filled hollow profile ( 5 ) with the molded-on shape and / or functional structures ( 6 ) and g) heating the core ( 1 ) to at least the melting temperature of the core ( 1 ) while melting the core material from the hollow profile ( 4 ). Injection molding method according to claim 1, comprising the step h) cleaning the hollow profile ( 4 ). Injection molding method according to claim 1 or 2, wherein the core ( 1 ) is made of a low-melting metal or a metal alloy, preferably from Sri and / or Bi, whose / whose melting temperature is lower than the melting temperature of the thermoplastic injection molding material used and the decomposition temperature thermosetting matrix plastic. Injection molding method according to at least one of claims 1 to 3, wherein the fiber material ( 2 ) Comprises fibers, bundles, tapes / ribbons of reinforcing fibers selected from mineral fibers, glass fibers, carbon fibers, polymer fibers, aramid fibers, natural fibers, or combinations thereof. Injection molding method according to at least one of claims 1 to 4, comprising the step of: forming the core ( 1 ) with a complex geometry that has undercuts or breakthroughs. Injection molding method according to at least one of claims 1 to 5, comprising the step: in step c), multilayer winding on the core of the fiber material ( 2 ), thereby preferably power flow oriented arranging the fibers. Injection molding method according to at least one of claims 1 to 6, comprising the step of: heating the core ( 1 ) to at least the melting temperature of the core ( 1 ) in step d) by the preheated injection molding tool ( 11 ). An injection molding method according to at least one of claims 1 to 7, comprising the steps of: selecting the thermosetting matrix material and the thermoplastic resin with regard to their adhesion properties to one another and / or during the casting of the core ( 1 ) and / or winding the fiber material ( 2 ) Generating positive locking elements on the core-filled hollow profile ( 3 ) for injection molding and / or functional structures ( 5 ). An injection molding method according to at least one of claims 1 to 8, comprising the steps of: after step g) picking up the core material removed from the hollow profile and recycling the process step a) for casting a further core ( 1 ). Fiber composite hollow preformed component with injection molded and / or functional structures, suitable for use as a motor vehicle component, characterized in that the fiber composite hollow profile component ( 3 ) a fiber winding ( 2 ) with a thermosetting matrix and form or / and functional structures arranged above or thereon ( 5 ) made of thermoplastic material.

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