DE102014004158A1 - Process for the production of structural elements from load introduction element and fiber-plastic composite hollow profile and structural elements - Google Patents

Abstract

The invention relates to a method for producing structural elements (1) from load introduction element (3) and fiber-plastic composite hollow profile (2) with thermoplastic matrix material and structural elements, the method comprising the following steps: - inserting with at least one undercut (6) provided load introduction element (3) in the fiber-plastic composite hollow profile (2) for forming a structural element semifinished product, - local heating of the fiber-plastic composite hollow profile (2) to the deformability of the fiber-plastic composite hollow profile ( 2) in the region of the undercut (6) of the load introduction element (3), inserting the structural element semifinished product into a tool, the above-mentioned method steps optionally being carried out differently in their sequence, injection molding of the deformable fiber-plastic composite hollow profile (2 ) with flowable injection molding compound (41) in the tool in the region of the undercut of the load introduction element ment (3) for forming at least one undercut (13) of the fiber-plastic composite hollow profile (2), wherein the formed undercuts (13) fiber-plastic composite hollow profile (2) precisely to the undercuts (6) of the load introduction element (3) are joined to one another at least in a form-fitting manner, solidification of the flowable injection molding compound (41) to at least one in the undercuts (13) of the fiber-plastic composite hollow profile (2) to form a shaped piece (4) and thus to the final structural element (1), - removal of the final structural element (1) from the tool.

Description

The invention relates to a method for the production of structural elements of load introduction element and fiber-plastic composite hollow profile with thermoplastic matrix material and structural elements.

A form-fitting installation of load introduction elements in solid rods with axial fiber reinforcement is in the document DE 10 2004 038 082 B4 described. Both the rod and the connection of the load introduction element to the rod are only suitable for the transmission of tensile forces. The combination element is not suitable for transmitting pressure or torques and is also not transferable to hollow profiles.

An axial compression of thermoplastic pipe ends is in the document GB 2 160 144 A described. The connection is intended for the transmission of axially acting tensile loads and can not be transferred to continuous fiber-reinforced hollow profiles.

An arrangement in which the ends of the hollow profile pressed flat and then encapsulated with injection molding compound is in the document DE 10 2010 041 790 A1 described. The hollow profile is supported neither during forming nor during injection from the inside and therefore either undefined reshaped or collapsed. In addition, the bore for connection of the adjoining elements is rotated by an angle of 90 ° to the profile axis, so that only certain connection elements that usually require additional space, such. As forks, can be used. The specified element is not suitable for transmitting moments.

Load introduction for fiber composite rods are in the publications DE 10 2006 039 565 A1 . DE 102 49 591 A1 . DE 10 2004 021 144 A1 and JP 2004 291 505 A described, wherein the load introduction load introduction elements by bonding material and / or frictionally connected to the corresponding fiber composite rods. Due to the lack of positive connection such load introduction elements are only applicable up to a limited load height and unsuitable for highly loaded hollow profiles. In addition, bonded structures often have a low robustness. They are susceptible to aging and thermal induced stresses.

Arrangements given in the publications DE 10 2008 057 893 A1 . DE 20 2008 008 821 U1 are not suitable for endlessly produced semi-finished products with a constant cross-section.

Load introduction elements, which are formed directly in the manufacturing process, are in the document WO 2005/105417 A1 described. For each profile length to be produced, a separate tool is required. The method is suitable exclusively for molding the composite profiles into the metallic load introduction elements, which requires additional space for the external load introduction elements and requires additional consideration of the thermal expansions against externally formed load introduction elements in order to prevent detachment of the load introduction elements.

The transformation of a thermoset fiber composite by means of an expansion body is in the document EP 0 311 837 B1 described. Spreader and tendon work together preferably via conical surfaces. The power transmission takes place via the expanded spreader.

Injection of a functional element to a rod-shaped component of fiber-reinforced thermoplastic material is in the document DE 10 2012 020 184 A1 described. The functional element is made of a braided preform, which is molded by means of hydroforming to an external tool. Before or after cooling, the functional element is then injection-molded, wherein the cross-section, which is molded onto, does not have to be round. The process requires complete heating of the preform and support by internal pressure. The preform is not preconsolidated, the forming process takes place only by internal pressure. Thus, several process steps are always necessary.

A device and a method for injecting functional elements on formed by hydroforming in a tool profiles of preconsolidated fiber reinforced thermoplastic material are in the document DE 10 2011 108 219 A1 described. The pre-consolidated semi-finished product is heated and placed in a tool using a handling system. Then the forming process takes place. In a subsequent step, a functional element is molded onto the reshaped profile.

Disadvantages of the method are the need for several steps for the production of the functional element by a separation of forming process and Anspritzprozess and the lack of flexibility in the positioning of the functional elements.

A fiber composite profile, in particular a car bumper is in the document DE 10 2009 056 472 A1 described. The fiber composite profile consists of pultruded and retrofitted bent thermoplastically deformed fiber-reinforced thermoplastics. To the profile are in a downstream step functional elements, eg. As flanges or ribs, molded. The disadvantage here is also the lack of flexibility of Anspritzprozesses. In addition, the bend-technical forming of axially reinforced fiber composite profiles with a large cross section is only possible to a limited extent because the fibers can neither plastically stretch nor compress without kinking.

The injection molding of a form-fitting fixed functional element to a thermoplastic fiber composite component is in the document DE 10 2007 060 628 A1 described. In this case, depressions or bulges are produced on the profile in a first step by means of a local forming process. The recesses are enclosed and filled by the injection molding compound applied in a subsequent step, whereby it is positively connected to the basic component. The disadvantage here is the requirement of several process steps for generating the positive connection. In addition, the method relates to a component produced in a single process and it is not possible to vary the position of the molded elements without adaptation of the tool.

A method for molding rib structures on a hollow profile body is in the document DE 100 14 332 A1 described. In this case, the body is surrounded at several discrete connection points by the injection molding compound, whereby a positive connection is formed. In addition, the positive locking geometry is generated in an upstream step, whereby here again several process steps are necessary.

The injection molding of rib structures on a fiber composite component is in another document DE 10 2006 010 271 A1 described. The fiber composite component is heated in a first step, wherein particular positions at which later the ribs are molded, are heated above the melting temperature in order to achieve a good connection of the injection molding material to the base material. Subsequently, the component is placed in an injection mold, which is closed. From one side, the rib structures are now molded. In this case, it is possible to provide depressions in the opposite side of the injection molding tool, into which the base material is molded during the injection molding process in order to produce a positive fit. A disadvantage of the method is the restriction to largely flat components. The production of hollow structures is not possible.

A method for expanding a fiber composite hollow profile in a final shape by means of fluidic internal pressure is in the document DE 10 2007 017 414 A1 described, wherein the hollow profile is overmolded in the expansion area with an injection molding material. This can be done simultaneously with the widening or, in order to reduce the cycle time and produce a highly accurate reproducible contour. With simultaneous forming and injection molding, the internal pressure in the profile is used to build up a pressure on the injection molding compound and thus to minimize shrinkage. A disadvantage of the method, the relatively undefined deformation of the profile to the outside and the required internal pressure, whereby the process engineering design, especially in the context of a mass production process, is complicated.

A method for molding a metallic hollow body is in the document DE 10 2006 038 930 A1 described, wherein the tubular body extends through the cavity of an injection molding tool. In order to prevent deformation of the tubular body during the injection molding process, an internal pressure is applied to the tubular body, which counteracts the injection molding pressure.

A disadvantage of the method is the non-existing positive connection. Since it is also an overmolded metallic molded body, the fixation of the injection molding material is not guaranteed by a material connection, but only by the frictional connection, which is caused by shrinkage of the plastic and optionally by adhesion corresponding adhesion forces. Furthermore, a free positioning of the injection molded part on the base body is also not possible here.

In the publication DE 19 538 360 C1 a completely short-fiber-reinforced thermoplastic flange is used, which forms an undercut via holes drilled in the fiber composite pipe in advance. Again, in principle, a semi-finished tube can be used. There is no deformation of the pipe.

The invention is therefore based on the object of specifying a method for producing structural elements of load introduction element and fiber-plastic composite hollow profile with thermoplastic matrix material and structural elements, which are designed so suitable that an automatable and efficient integration of load introduction elements in endless fiber reinforced, endless manufacturable Hollow profiles with a thermoplastic matrix for material and force flow appropriate introduction of axial forces, torques and / or possibly additional acting bending moments is possible. In addition, a positive and possibly also material and / or non-positive connection of an endlessly producible fiber-plastic composite hollow profile with a compact Load introduction element are formed into a structural element over which a material-appropriate introduction of loads (tensile / compressive forces, torques and bending moments or a combination of these) can be created. It is a structural element of load introduction element and functional element to fiber-plastic composite hollow structures are created, with a combined automatable production and a positionally variable positive and cohesive connection of thermoplastic functional elements (transmission components, levers, eccentric, bearing seats) on / on endless fiber reinforced, endless or discontinuously produced hollow profiles are possible.

• – Einfügen des mit mindestens einem Hinterschnitt versehenen Lasteinleitungselements in das Faser-Kunststoff-Verbund-Hohlprofil zur Ausbildung eines Strukturelement-Halbzeugs,
• – Lokales Erwärmen des Faser-Kunststoff-Verbund-Hohlprofils bis zur Verformbarkeit des Faser-Kunststoff-Verbund-Hohlprofils im Bereich des Hinterschnitts des Lasteinleitungselements,
• – Einlegen des Strukturelement-Halbzeugs in ein Werkzeug, wobei die drei vorgenannten Schritte in unterschiedlich veränderter Abfolge durchgeführt werden können,
• – Anspritzen des verformbaren Faser-Kunststoff-Verbund-Hohlprofils mit fließfähiger Spritzgussmasse im Werkzeug in den Bereich des Hinterschnitts des Lasteinleitungselements zur Ausbildung mindestens eines Hinterschnittes des Faser-Kunststoff-Verbund-Hohlprofils, wobei die ausgebildeten Hinterschnitte des Faser-Kunststoff-Verbund-Hohlprofils passgenau an die Hinterschnitte des Lasteinleitungselements zumindest formschlüssig aneinander gefügt sind,
• – Erstarren der fließfähigen Spritzgussmasse zu mindestens einem in den Hinterschnitten des Faser-Kunststoff-Verbund-Hohlprofils zur Ausbildung eines Formstücks und somit zu dem finalen Strukturelement,
• – Entformen des finalen Strukturelements aus dem Werkzeug.

The object is solved by the features of claims 1, 2 and 6, 7. The process for the production of structural elements of load introduction element and fiber-plastic composite hollow profile with thermoplastic matrix material
comprises according to claim 1
at least the following steps:

• Inserting the load introduction element provided with at least one undercut into the fiber-plastic composite hollow profile to form a structural element semifinished product,
• Local heating of the fiber-plastic composite hollow profile up to the deformability of the fiber-plastic composite hollow profile in the region of the undercut of the load introduction element,
• Inserting the structural element semifinished product into a tool, wherein the three aforementioned steps can be carried out in differently modified sequence,
• - Injection of the deformable fiber-plastic composite hollow profile with flowable injection molding compound in the tool in the region of the undercut of the load introduction element for forming at least one undercut of the fiber-plastic composite hollow profile, wherein the formed undercuts of the fiber-plastic composite hollow profile fit are joined to the undercuts of the load introduction element at least form-fitting to each other,
• Solidification of the flowable injection molding compound to at least one in the undercuts of the fiber-plastic composite hollow profile to form a molding and thus to the final structural element,
• - Removal of the final structural element from the tool.

• – Einfügen des mit mindestens einem Hinterschnitt versehenen Lasteinleitungselements in Form eines konturgebenden Elements in das Faser-Kunststoff-Verbund-Hohlprofil zur Ausbildung eines Strukturelement-Halbzeugs,
• – Lokales Erwärmen des Faser-Kunststoff-Verbund-Hohlprofils bis zur Verformbarkeit des Faser-Kunststoff-Verbund-Hohlprofils im Bereich des Hinterschnitts des konturgebenden Elements,
• – Einlegen des Strukturelement-Halbzeugs in ein Werkzeug, wobei die drei vorgenannten Schritte in unterschiedlich veränderter Abfolge durchgeführt werden können,
• – Anspritzen des verformbaren Faser-Kunststoff-Verbund-Hohlprofils mit fließfähiger Spritzgussmasse im Werkzeug in den Bereich des Hinterschnitts des konturgebenden Elements zur Ausbildung mindestens eines Hinterschnittes des Faser-Kunststoff-Verbund-Hohlprofils, wobei die ausgebildeten Hinterschnitte des Faser-Kunststoff-Verbund-Hohlprofils passgenau an die Hinterschnitte des konturgebenden Elements zumindest formschlüssig aneinander gefügt sind,
• – Erstarren der fließfähigen Spritzgussmasse zu mindestens einem in den Hinterschnitten des Faser-Kunststoff-Verbund-Hohlprofils ausgebildeten Funktionselement und somit zu dem finalen Strukturelement,
• – Entformen des finalen Strukturelements aus dem Werkzeug.

Another method for the production of structural elements of load introduction element and fiber-plastic composite hollow profile with thermoplastic matrix material
comprises according to claim 2
at least the following steps:

• Inserting the load introduction element provided with at least one undercut in the form of a contouring element into the fiber-plastic composite hollow profile to form a structural element semifinished product,
• Local heating of the fiber-plastic composite hollow profile up to the deformability of the fiber-plastic composite hollow profile in the region of the undercut of the contouring element,
• Inserting the structural element semifinished product into a tool, wherein the three aforementioned steps can be carried out in differently modified sequence,
• - Injection of the deformable fiber-plastic composite hollow profile with flowable injection molding compound in the tool in the region of the undercut of the contouring element to form at least one undercut of the fiber-plastic composite hollow profile, wherein the formed undercuts of the fiber-plastic composite hollow profile accurately fitted to the undercuts of the contouring element at least form-fitting together,
• Solidification of the flowable injection molding compound to at least one functional element formed in the undercuts of the fiber-plastic composite hollow profile and thus to the final structural element,
• - Removal of the final structural element from the tool.

The load introduction element can be used within the fiber-plastic composite hollow profile at the same time as contouring and supporting element or after its removal from the fiber-plastic composite hollow profile as only necessary in the manufacturing process contouring element.

The undercuts may be formed in the axial direction to the hollow profile axis and / or in the circumferential direction.

• – ein Lasteinleitungselement mit mindestens einem Hinterschnitt, wobei das Lasteinleitungselement in das Faser-Kunststoff-Verbund-Hohlprofil eingefügt ist,
• – zumindest einen in den Hinterschnitt des Lasteinleitungselement passgenau anliegenden Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils in formschlüssiger Verbindung in Form eines Struktur-Halbzeuges,
• – ein in den Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils eingreifendes und angespritztes Formstück, das aus einer unter Druck injizierten Schmelze einer Spritzgussmasse und nachfolgend erstarrten Spritzgussmasse besteht,
• – wobei durch das Anspritzen der geschmolzenen Spritzgussmasse an den das Formstück stützenden Hinterschnitt eine form- oder stoffschlüssige Verbindung zwischen dem Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils und dem erstarrten Formstück ausbildet und damit ein finales Strukturelement entsteht.

A first structural element, which contains at least one fiber-plastic composite hollow profile with thermoplastic matrix material, can be produced by one of the aforementioned methods,
wherein it further comprises according to claim 4

• A load introduction element having at least one undercut, the load introduction element being inserted into the fiber-plastic composite hollow profile,
• At least one undercut of the fiber-plastic composite hollow profile fitting in the undercut of the load introduction element in positive connection in the form of a structural semi-finished product,
• - An engaging in the undercut of the fiber-plastic composite hollow profile and molded molding which consists of a pressure-injected melt of an injection molding compound and subsequently solidified injection molding compound,
• - Wherein by injecting the molten injection molding material to the fitting supporting the undercut forms a positive or cohesive connection between the undercut of the fiber-plastic composite hollow profile and the solidified molding and thus creates a final structural element.

• – wahlweise ein konturgebendes Element mit mindestens einem Hinterschnitt, wobei das konturgebende Element in das Faser-Kunststoff-Verbund-Hohlprofil eingefügt ist,
• – zumindest einen in den Hinterschnitt des konturgebenden Elements passgenau anliegenden Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils in formschlüssiger Verbindung in Form eines Struktur-Halbzeuges,
• – ein in den Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils eingreifendes und angespritztes Funktionselement, das aus einer unter Druck injizierten Schmelze einer Spritzgussmasse und nachfolgend erstarrten Spritzgussmasse besteht,
• – wobei durch das Anspritzen der geschmolzenen Spritzgussmasse an den das Funktionselement stützenden Hinterschnitt eine form- und/oder stoffschlüssige Verbindung zwischen dem Hinterschnitt des Faser-Kunststoff-Verbund-Hohlprofils und dem erstarrten Funktionselement ausbildet und sich damit ein finales Strukturelement bildet.

A second structural element, at least made of a fiber-plastic composite hollow profile with thermoplastic matrix material and designed as Lasteinleitungslement contour-forming element, according to claim 5 at least

• Optionally a contouring element having at least one undercut, the contouring element being inserted in the fiber-plastic composite hollow profile,
• At least one undercut of the fiber-plastic composite hollow profile, which fits snugly in the undercut of the contouring element, in positive connection in the form of a structural semi-finished product,
• A functional element which engages in the undercut of the fiber-plastic composite hollow profile and which consists of a melt injected under pressure of an injection molding compound and subsequently solidified injection molding compound,
• - Wherein by injecting the molten injection molding material to the functional element supporting undercut forms a positive and / or cohesive connection between the undercut of the fiber-plastic composite hollow profile and the solidified functional element and thus forms a final structural element.

The solidified in the undercut of the fiber-plastic composite hollow profile or the solidified functional element can serve as a pressure piece to support the formed positive connection.

The molded and solidified fitting can be designed as a functional element that has been formed in the cavity of the tool.

The load introduction element and the contour-bound element can be connected to the fiber-plastic composite hollow profile in accordance with the material and force flow.

The undercuts are pronounced with respect to the load of the final structural element.

The injection molding compound may have a low density.

The load introduction element and the contouring element may be thin-walled.

With a relatively smooth surface of the fiber-plastic composite hollow profile, the regions of the molded undercuts at least reinforcing layer or in particular sleeve may be mounted around the molding.

The molded piece and the functional element may be molded locally with injection molding compound of thermoplastic matrix material.

The molded piece may be formed in a modified form as a functional element, wherein the functional element is molded in the region of the undercut of the fiber-plastic composite hollow profile, so that at least one positive connection of the functional element is present on the fiber-plastic composite hollow profile.

The load introduction element can serve as a contouring element / contouring element / undercut form element and as a support element.

The load introduction element and the contouring element can be made of solid material z. B. be made of metal or plastic.

The contouring element can, for. Example, be made of sand or from a detachable or washable material and be removable after the solidification of the functional element of the fiber-plastic composite (FKV) hollow profile.

In the following, the essence of the method and structural elements according to the invention will be explained in detail. The structural element according to the invention is created, in particular, by a load-introduction element introduced into the FKV hollow profile in a form-fitting manner (and, if appropriate, frictionally and cohesively), the load introduction element having at least one undercut.

The core of the invention is the forming of at least part of a consolidated and locally heated fiber-reinforced hollow profile in the undercuts of a load introduction element by pressure-injected preferably thermoplastic melt. The melt fills out the undercut and is used after solidification as a pressure piece to support a positive connection between the load introduction element and FKV hollow profile.

The expression of the undercuts can be adapted to the loads of the application. An automated installation of the load introduction element can be carried out by targeted local deformation of the fiber-plastic composite hollow structure by injection molding. For this purpose, the fiber-plastic composite profile is locally heated to achieve a formability, and formed with the printed injection molding compound in the undercuts of the load introduction element. When loading the connection, a radial expansion can be prevented by a sleeve and thus preserve the positive connection. The necessary for preventing the expansion tailor-made form element is accurately produced during the forming of injection molding compound.

Due to the primary reshaping of the fiber-plastic composite hollow profile, depending on the coordination of the process parameters and the geometry of the load introduction element, only a precise contact of the two joining partners is achieved. After applying a mechanical load, a cavity can arise at this contact point due to elastic strains. This effect can be counteracted by a bias of the joining partners. One possibility here is to inject injection molding compound at high pressure into this contact point in a second process step. This causes a joint pressure corresponding to the desired bias. In addition - especially when using metallic load introduction elements - so an intermediate layer can be generated, which isolates the fiber-plastic composite profile and the load introduction element from each other and prevents electrochemical corrosion.

• – einem Umformen des Hohlprofils und Füllen des Hinterschnitts in einem Prozessschritt,
• – einer Robustheit des Verfahrens gegenüber Toleranzabweichungen des Lasteinleitungselements im Vergleich zu starren Füllkörpern und einer Reduktion des notwendigen Fertigungsaufwandes für die Lasteinleitungselemente,
• – einer Anformung der Lastleitungselemente ohne Werkzeuganpassungen an beliebig lange Hohlprofile,
• – einer Variation einer Ausprägung des Hinterschnitts auf dem Lasteinleitungselements ohne Anpassungen am Werkzeug,
• – einer Verwendung von endlos und damit effizient herstellbaren Hohlprofilen,
• – einer Automatisierbarkeit der Herstellung von Strukturelementen mittels Integration von Lasteinleitungselementen in faserverstärkte Hohlprofile.

The advantages of the invention with respect to the method consist in

• A forming of the hollow profile and filling of the undercut in a process step,
• A robustness of the method in relation to tolerance deviations of the load introduction element in comparison to rigid packing and a reduction of the necessary production outlay for the load introduction elements,
• - Anformung the load line elements without tool adjustments to arbitrarily long hollow sections,
• A variation of an expression of the undercut on the load introduction element without adjustments to the tool,
• - a use of endless and thus efficiently manufacturable hollow sections,
• - An automation of the production of structural elements by integration of load introduction elements in fiber-reinforced hollow profiles.

• – einer werkstoff- und kraftflussgerechten Anbindung des metallischen Lasteinleitungselements an das faserverstärkte Hohlprofil,
• – einem minimalen zusätzlichen Bauraumbedarf,
• – einer Anpassung der Ausprägung des Hinterschnitts an den Belastungszustand,
• – einem sehr hohen Leichtbaupotential durch die geringe Dichte der Spritzgussmasse, die Verwendung dünnwandiger Lasteinleitungselemente, die Verwendung unidirektional verstärkter Verstärkungshülsen,
• – einer lokalen Aufdickung des Formstücks, wodurch das volle Potential der ungestörten Tragstruktur genutzt werden kann, wobei die Lasteinleitungselemente individuell entsprechend den anzubindenden Komponenten angepasst werden können.

The advantages of the invention with respect to a structural element consist in

• A connection of the metallic load introduction element to the fiber-reinforced hollow profile in accordance with the material and force flow,
• - a minimal additional space requirement,
• - an adaptation of the expression of the undercut to the load condition,
• A very high lightweight potential due to the low density of the injection molding compound, the use of thin-walled load introduction elements, the use of unidirectionally reinforced reinforcing sleeves,
• - A local thickening of the fitting, whereby the full potential of the undisturbed support structure can be used, the load introduction elements can be adjusted individually according to the components to be connected.

The invention is also concerned with the design and production technology implementation of functional elements in an extension of the connection of the fittings as functional elements. Depending on the characteristics of the functional element, axial loads, bending moments and, in particular, torsional moments are introduced into the structure of the non-load-transmitting fiber composite structure while substantially dispensing with foreign materials such as steel or titanium. The functional element is molded onto the fiber-plastic composite structure, wherein the fiber-plastic composite structure locally deformed rests on a support structure. The thereby forming between the functional element and the hollow profile undercut is used under load of the functional element for the positive transmission of forces and moments, which allows a positive connection of the functional element (injection molding).

In this case, the cross-section of the thermoplastic fiber-plastic composite hollow profile / tube is locally supported during injection molding by a predetermined contour-bound form element corresponding to the contoured with at least one undercut load introduction element. This can be z. B. also consist of a thin contoured metallic sleeve or a contoured plastic part. In this case, the support element remains after production in the hollow profile. Another possibility is the use of washable sand cores or inflatable contoured cores, whereby the support element can be removed after the injection molding process. Contouring form elements can be applied at a predetermined location of a given long fiber-plastic composite hollow profile by a predetermined inner tool design, wherein the tool does not have to be changed even with a change in the edge distance. As a result, high customizability of shaft or rod systems in the series production process is possible.

The present invention thus also describes a method for producing a form-fitting and cohesively bonded functional element made of (fiber-reinforced) thermoplastic on a continuous fiber-reinforced hollow profile.

The functional element is positively connected via an undercut contour and, if appropriate, additionally non-positively and / or materially connected to the hollow profile. The expression of the undercuts is adapted to the load present in the application. The contour-bound support element can remain connected or removed depending on the nature of the injection process in the component. A remaining support element z. B. in the form of a metal sleeve, supports the cross section of the hollow profile in addition and improves the mechanical properties of the load application area. Depending on the loads occurring, the lightweight design can be increased by the choice of a given support element.

In the inventive, at least one functional element-containing structural element is the production and connection of a thermoplastic functional element on an endless fiber reinforced hollow profile in a process step substantially, wherein the functional element cohesively and, by a resulting in the manufacturing process of the functional element undercut, can be positively connected to the hollow profile.

• – einer werkstoff- und kraftflussgerechten Anbindung des Funktionselements an die faserverstärkte Hohlstruktur,
• – einer Anpassung der Ausprägung des Hinterschnitts an den Belastungszustand,
• – einem sehr hohen Leichtbaupotential mit geringer Dichte der Spritzgussmasse, mit Verwendung dünnwandiger und wahlweise nachträglich entfernbarer formgebender Elemente, mit angepassten Eigenschaften durch Mehrkomponentenspritzguss, wobei keine zusätzlichen Fügeelemente notwendig sind,
• – einer Nutzung des vollen Potenzials der ungestörten Tragstruktur durch lokale Aufdickung des Funktionselementbereichs,
• – einem stoffgleichen Strukturelement aus Funktionselement und Hohlprofil, wobei daher reduzierte zusätzliche Herausforderungen in den Bereichen der Kontaktkorrosion sowie induzierten Spannungen in Folge von differierenden Wärmeausdehnungskoeffizienten vorhanden sind.

The advantages of the invention with respect to the structural element containing the functional element in connection with the hollow profile consist in

• A connection of the functional element to the fiber-reinforced hollow structure in accordance with the material and force flow,
• - an adaptation of the expression of the undercut to the load condition,
• A very high lightweight potential with low density of the injection molding compound, with use of thin-walled and optionally subsequently removable shaping elements, with adapted properties by multi-component injection molding, wherein no additional joining elements are necessary,
• A utilization of the full potential of the undisturbed supporting structure by local thickening of the functional element area,
• - A fabric-like structural element of functional element and hollow profile, which therefore reduced additional challenges in the areas of contact corrosion and induced stresses due to differing thermal expansion coefficients are present.

• – einem Umformen des Hohlprofils und Erzeugen eines Funktionselements in einem Prozessschritt,
• – einem Anspritzen der Funktionselemente ohne Werkzeuganpassungen an vorgegebener Stelle auf beliebig lange Hohlhalbzeuge,
• – eine Variierung der Ausprägung des durch den Anspritzprozess entstehenden Hinterschnitts im Profil ohne Anpassungen am Außenwerkzeug, wobei nur das konturgebende Element angepasst werden muss,
• – einer Verwendung von endlos und damit effizient herstellbaren Hohlprofil-Halbzeugen,
• – einer hohen Automatisierbarkeit und einer gleichzeitigen Flexibilität bei der Integration von Funktionselementen in den Hinterschnitten des Faser-Kunststoff-Verbund-Hohlprofils.

The advantages of the method for producing at least one structural element containing a functional element consist in

• A forming of the hollow profile and producing a functional element in a process step,
• - Injection of the functional elements without tool adjustments at a predetermined point on arbitrarily long hollow semi-finished products,
• A variation in the shape of the undercut produced in the profile by the injection molding process without adjustments to the external tool, whereby only the contouring element has to be adapted,
• A use of endless and thus efficiently producible hollow profile semi-finished products,
• - A high degree of automation and a simultaneous flexibility in the integration of functional elements in the undercuts of the fiber-plastic composite hollow profile.

Further developments and additional advantageous embodiments of the invention are specified in further subclaims.

The invention will be described by means of exemplary embodiments with reference to several drawings. It shows:

1 a schematic representation of the structure of a structural element of a fiber-plastic composite hollow profile with a thermoplastic matrix and of a molded provided with undercut load introduction element, wherein the 1a an enlarged longitudinal sectional view shows

2 a cross-sectional view of the structural element AA 1 and 1a .

3 a first method step: heating the fiber-reinforced hollow profile, in the cylindrical free space of which an undercut load introduction element is inserted before the formation of a structural element semifinished product, before insertion into a tool for carrying out the injection molding method,

4 a second method step: inserting the heated structural element semifinished product into the mold for carrying out the injection molding method,

5 a third process step: injection molding of melt of an injection molding compound via cavity lines of the tool in the region of the undercuts of the load introduction element and forming the heated structure element semifinished product to the final structural element with holding injection molding compound,

6 a schematic longitudinal sectional view of the structure of a structural element made of a fiber-plastic composite hollow structure and a molded-functional element,

7 a cross-sectional view AA of the structural element according to 6 .

8th a first process step of the process for producing the structural element according to 6 and 7 : Heating the fiber-plastic composite profile in the region of the undercuts of the inserted as a support element contour-bound element, wherein 8a a cross section BB according to 8th shows,

9 a second method step of the process for producing the structural element: inserting the locally heated structural element semifinished product into the injection region of the tool,

10 a third process step of the process for producing the structural element: injection molding of the functional element with a melt of the injection molding compound and pressure-induced deformation of the heated fiber-plastic composite hollow profile to the undercuts of the supporting contouring element and forming the final structural element in the tool cavity provided therefor.

In 1 is a schematic representation of the structure of a structural element 1 made of a fiber-plastic composite hollow profile 2 with thermoplastic matrix - fiber-thermoplastic composite hollow section - and from a molded with undercuts 6 provided load introduction element 3 , shown, wherein the 1a an enlarged longitudinal sectional view of the structural element 1 shows,

In 2 is a cross-sectional view AA of the structural element 1 to 1 and 1a specified.

In 3 is in a first process step: heating 26 of the fiber-reinforced hollow profile 2 , in whose cylindrical space one with undercuts 6 provided load introduction element 3 for the formation of a structural element semifinished product 15 is inserted before inserting into a tool 10 shown for subsequent implementation of the injection molding process.

The 4 shows a second method step: insert 27 and positioning the heated structural element semifinished product 15 in the tool 10 to carry out the injection molding process.

In 5 is a third process step: Injection 28 of injection molding compound 41 over cavity pipes 17 of the tool 10 in the area of the undercuts 6 of the load introduction element 3 and forming the heated structural element semifinished product 15 to the structural element 1 with a holding injection molding compound 4 shown.

• – Einfügen des mit mindestens einem Hinterschnitt 6 versehenen Lasteinleitungselements 3 in das Faser-Thermoplast-Verbund-Hohlprofil 2 zur Ausbildung eines Strukturelement-Halbzeugs 15,
• – Lokales Erwärmen des Faser-Thermoplast-Verbund-Hohlprofils 2 bis zur Verformbarkeit des Faser-Thermoplast-Verbund-Hohlprofils 2 im Bereich des Hinterschnitts 6 des Lasteinleitungselements 3,
• – Einlegen des Strukturelement-Halbzeugs 15 in ein Werkzeug 10, wobei die Abfolge der vorgenannten Schritte auch vertauscht sein kann,
• – Anspritzen des verformbaren Faser-Thermoplast-Verbund-Hohlprofils 2 mit fließfähiger vorzugsweise thermoplastischer Spritzgussmasse 41 im Werkzeug 10 in den Bereich des Hinterschnitts 6 des Lasteinleitungselements 3 zur Ausbildung mindestens eines Hinterschnittes 13 des Faser-Thermoplast-Verbund-Hohlprofils 2, wobei die ausgebildeten Hinterschnitte 13 Faser-Thermoplast-Verbund-Hohlprofils 2 passgenau an die Hinterschnitte 6 des Lasteinleitungselements 3 zumindest formschlüssig aneinander gefügt sind,
• – Erstarren der fließfähigen Spritzgussmasse 41 zu mindestens einem in den Hinterschnitten 13 des Faser-Thermoplast-Verbund-Hohlprofils 2 ausgebildeten Formstück 4 und somit zu dem finalen Strukturelement 1,
• – Entformen des finalen Strukturelements 1 aus dem Werkzeug 10.

The method for producing a structural element 1 from a load introduction element 3 and a fiber-thermoplastic composite hollow section 2 with thermoplastic matrix material,
includes at least the following steps:

• - Insert the with at least one undercut 6 provided load introduction element 3 in the fiber-thermoplastic composite hollow section 2 for the formation of a structural element semifinished product 15 .
• - Local heating of the fiber-thermoplastic composite hollow profile 2 until the deformability of the fiber-thermoplastic composite hollow profile 2 in the area of the undercut 6 of the load introduction element 3 .
• - Inserting the structural element semifinished product 15 into a tool 10 wherein the sequence of the aforementioned steps may also be reversed,
• - Injection of the deformable fiber-thermoplastic composite hollow profile 2 with flowable preferably thermoplastic injection molding compound 41 in the tool 10 in the area of the undercut 6 of the load introduction element 3 for the formation of at least one undercut 13 of the fiber-thermoplastic composite hollow profile 2 , where the formed undercuts 13 Fiber thermoplastic composite hollow profile 2 perfectly fitting to the undercuts 6 of the load introduction element 3 at least positively connected to each other,
• - Solidification of the flowable injection molding compound 41 at least one in the undercuts 13 of the fiber-thermoplastic composite hollow profile 2 trained fitting 4 and thus to the final structural element 1 .
• - Removal of the final structural element 1 from the tool 10 ,

The load introduction element 3 within the fiber-thermoplastic composite hollow profile 2 can be used simultaneously as contouring and supporting element / undercut-form element.

• – ein Lasteinleitungselement 3 mit mindestens einem Hinterschnitt 6, wobei das Lasteinleitungselement 3 in das Faser-Thermoplast-Verbund-Hohlprofil 2 eingefügt ist,
• – zumindest einen in den Hinterschnitt 6 des Lasteinleitungselement 3 passgenau anliegenden Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 2 in formschlüssiger Verbindung in Form eines Struktur-Halbzeuges 15,
• – ein in den Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 2 eingreifendes und angespritztes Formstück 4, das aus einer unter Druck injizierten vorzugsweise thermoplastischen Schmelze einer Spritzgussmasse 41 und nachfolgend erstarrten Spritzgussmasse 41 besteht,
• – wobei durch das Anspritzen 28 der geschmolzenen Spritzgussmasse 41 an den das Formstück 4 stützenden Hinterschnitt 13 eine form- oder stoffschlüssige Verbindung zwischen dem Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 2 und dem erstarrten Formstück 4 ausbildet und damit ein finales Strukturelement 1 entsteht.

The first structural element 1 contains at least one fiber-thermoplastic composite hollow profile 2 with thermoplastic matrix material and is produced by the aforementioned method and further comprises

• - A load introduction element 3 with at least one undercut 6 , wherein the load introduction element 3 in the fiber-thermoplastic composite hollow section 2 is inserted,
• - at least one in the undercut 6 the load introduction element 3 precisely fitting undercut 13 of the fiber-thermoplastic composite hollow profile 2 in positive connection in the form of a structural semi-finished product 15 .
• - one in the undercut 13 of the fiber-thermoplastic composite hollow profile 2 engaging and molded fitting 4 consisting of a preferably thermoplastic melt injected under pressure of an injection molding compound 41 and subsequently solidified injection molding compound 41 consists,
• - Wherein by the injection molding 28 the molten injection molding compound 41 to the fitting 4 supporting undercut 13 a positive or cohesive connection between the undercut 13 of the fiber-thermoplastic composite hollow profile 2 and the solidified fitting 4 forms and thus a final structural element 1 arises.

That in the undercut 13 of the fiber-thermoplastic composite hollow profile 2 solidified fitting 4 with thermoplastic matrix material can serve as a pressure piece to support the formed positive connection.

The load introduction element 3 can be adjusted to the fiber-thermoplastic composite hollow profile in accordance with material and force flow 2 be connected.

The undercuts 6 and 13 can in terms of burden 29 of the final structural element 1 Be pronounced.

The injection molding compound 41 may have a low density.

The load introduction element 3 can be thin-walled.

For a given relatively smooth surface of the fiber-thermoplastic composite hollow profile 2 can one the areas of the molded undercuts 13 reinforcing sleeve 7 around the fitting 4 to be appropriate.

The fitting 4 Can be made locally with injection molding compound 41 be sprayed.

The load introduction element 3 can z. B. be made of metal or plastic.

That in the 1 to 5 shown inserted hollow profile 2 consists of a fiber-thermoplastic composite, ie a combination of reinforcing fibers (eg glass fibers, basalt fibers, carbon fibers) and a thermoplastic matrix material (eg PA, PPA, PPS, PEEK). The orientation of the fibers can be adapted to the loads of the particular application. For predominantly tensile and pressure loaded hollow sections 2 the reinforcing fibers are predominantly axially oriented. For predominantly torsionally loaded hollow profiles 2 the reinforcing fibers are oriented predominantly at an angle of 45 °. The hollow profiles 2 can be continuous, z. B. in a pultrusion process, or discontinuously, for. B. in a Schlauchblasverfahren. You can have a constant, but also one over the length of the hollow section 2 have varying cross section, as in 2 is shown, which has a cross section AA of the manufactured structural element 1 to 1 represents.

It can be an additional reinforcement of the hollow profile 2 be made.

There is the possibility of the hollow profile 2 in the area of the undercuts 6 the load introduction element with at least one additional layer 14 reinforce, causing a failure in the undisturbed area of the hollow section 2 is shifted and thus the carrying capacity of the hollow profile 2 can be fully exploited. The location 14 can during the heating phase of the installation of the load introduction element 3 with warmed up and during the Anspritzvorgangs cohesively with the hollow profile 2 be connected as in 1 is shown.

The following is the load introduction element 3 described in more detail. The load introduction element 3 can be made of solid material, eg. B. be formed of metal or plastic. Preferably, a hydroformed metallic pipe section is provided. The geometric shape of the load introduction element 3 can be chosen so that the most uniform load transfer from the load introduction element 3 to the fiber-reinforced hollow profile 2 he follows. In this case, both the wall thicknesses and the expression of at least one undercut 6 be adjusted. Depending on the load 29 , as in 1 The undercuts can be shown 6 be provided in the axial direction, tangential direction or a combination of two directions. When designing the undercuts 6 is the deformation potential of the hollow semi-finished products to be formed 2 and 3 to take into account. As adjusted undercut geometry Hyperzykloide have proven, the extent of the circumference of the undisturbed hollow profile 2 corresponds, so that the fiber-reinforced hollow profile 2 formed in this area, but does not need to be stretched or compressed. To load a relative movement between the load introduction element 3 and the injection molding compound 4 To complicate, the surface of the load introduction element 3 additionally structured. For forwarding the loads, the load introduction element 3 depending on the application, z. B. with an internal thread or an external thread, a flange or an eye.

The following is the injection molding compound used 41 further characterized: the injection molding compound 41 can the matrix material of the hollow profile 2 correspond. Depending on the combination of materials, the injection molding compound 41 after solidification cohesively to the hollow profile 2 tie. In the manufacturing process, the injection molding compound 41 for forming the composite hollow profile 2 used. It is advantageous that the injection molding compound 41 to the geometry of the undercuts 6 adapts and thus a variation of the undercut geometry without adjustments to the injection molding compound tool 10 can be done.

To use a sleeve 7 above the area of the undercuts 6 at the first structural element 1 the following is indicated:
A stiff sleeve 7 prevents expansion of the load introduction element 3 in the radial direction and thus ensures the positive load transfer even at high loads. The sleeve 7 has high tangential stiffnesses to minimize radial expansion. The sleeve 7 can be made both metallic and from a fiber composite. For a fiber composite sleeve 7 Particularly steep fiber angles are suitable with respect to the longitudinal axis of the hollow profile 2 (Peripheral positions). For radial bias of the joint connection, the sleeve 7 on the cylindrical or conical outer surface 8th of the fitting 4 with the injection molding compound 41 be pressed on.

When loading the load introduction area, the loads from the hollow profile 2 positive (optionally additionally material and non-positive) over undercuts 6 in the load introduction element 3 transfer. The radial expansion of the connection area 16 is about the injection molding compound 41 of the fitting 4 and the sleeve 7 prevented. By the primary reshaping of the fiber-thermoplastic composite hollow profile 2 can - depending on the coordination of the process parameters and the geometry of the load introduction element 2 - Only one contact point of the two joining partners are achieved, wherein after applying a mechanical load 29 due to elastic strains a cavity at the contact point as well as a bias arise, wherein in a further step, an injection of flowable injection molding compound 41 produced at high pressure in the contact point a joint pressure corresponding to the bias and wherein the resulting intermediate layer, the fiber-thermoplastic composite profile 2 and the load introduction element 3 isolated from each other and prevents electrochemical corrosion.

The method steps are explained in greater detail below:

Step 1:

The fully consolidated fiber-thermoplastic composite hollow profile 2 is in the range of load application according to 3 locally heated to locally heat the thermoplastic matrix material to allow reshaping of the composite material. The warming 26 can be done in different ways (hot gas, infrared, induction, microwave). The load introduction element 3 may also be preheated to after insertion of the load introduction element 3 in the composite hollow profile 2 to reduce the heat dissipation and the deformability of the hollow section 2 to obtain.

Step 2:

Positioning the load introduction element 3 in the intended forming area 11 of the fiber-thermoplastic composite hollow profile 2 for the formation of the structural element semifinished product 15 and inserting the structural element semifinished product 15 from load introduction element 3 and fiber-thermoplastic composite hollow section 2 with locally softened forming area 11 in the injection mold 10 with associated inner Kavitätsleitungen 17 according to 4 ,

Step 3:

The fitting 4 comes with the molten injection molding compound 41 from the outside via the cavity pipes 17 on the still warm fiber-thermoplastic composite hollow profile according to 5 injected. By the pressure p of the injection molding compound 41 from one to the tool 10 connected injection unit 18 Forms the fiber-thermoplastic composite hollow profile 2 of the structural element semifinished product 15 in the undercuts 6 of the load introduction element 3 and gets on the outside surface 5 of the load introduction element 3 pressed and it forms even undercuts 13 , Which is on the outside 12 the situation 14 or the hollow profile 2 forming undercuts 13 be with the molten injection molding compound 41 filled. After solidification of the injection molding compound 41 can the reshaped fiber-thermoplastic composite hollow section 2 with the molded load introduction element 3 as a structural element 1 the tool 10 be removed. This is the tool 10 open.

Step 4:

On the outer contour 8th of the fitting 4 with the injected injection molding compound 41 can be a reinforcing sleeve 7 be applied / pulled. Alternatively, it is also possible, the reinforcing sleeve 7 directly into the tool 10 to lay and the injection molding compound 41 between the sleeve 7 and the hollow profile 2 to inject. To bias the connection area, the reinforcing sleeve 7 also be pressed. These are particularly suitable for a slightly conical outer contour 8th the molded injection molding compound 41 and a conical sleeve 7 ,

In a further industrially significant embodiment, the structural element 1 as a modified second structural element 20 realized application and function related. Instead of partially in the undercuts 13 of the hollow profile 2 located fitting 4 can be a functional element 42 in conjunction with a fiber-reinforced hollow profile 21 and a contouring element supporting a load introduction element 31 to be brought.

The 6 shows a schematic longitudinal sectional view of the structure of a structural element 20 from a fiber-thermoplastic composite hollow profile 21 from a molded functional element 42 and from a load introduction element 31 as a contouring element with undercuts 6 is trained.

In 7 is a cross-sectional view AA of the structural element 20 to 6 specified.

• – Einfügen des mit mindestens einem Hinterschnitt 6 versehenen Lasteinleitungselements 3 in Form eines konturgebenden Elements 31 in das Faser-Thermoplast-Verbund-Hohlprofil 21 zur Ausbildung eines Strukturelement-Halbzeugs 15,
• – Lokales Erwärmen des Faser-Thermoplast-Verbund-Hohlprofils 21 bis zur Verformbarkeit des Faser-Thermoplast-Verbund-Hohlprofils 21 im Bereich des Hinterschnitts des konturgebenden Elements 31,
• – Einlegen des Strukturelement-Halbzeugs 15 in ein Werkzeug 10, wobei die Abfolge der genannten Schritte unterschiedlich sein kann,
• – Anspritzen des verformbaren Faser-Thermoplast-Verbund-Hohlprofils 21 mit fließfähiger Spritzgussmasse 41 im Werkzeug 31 in den Bereich des Hinterschnitts des konturgebenden Elements 31 zur Ausbildung mindestens eines Hinterschnittes 13 des Faser-Thermoplast-Verbund-Hohlprofils 21, wobei die ausgebildeten Hinterschnitte 13 Faser-Thermoplast-Verbund-Hohlprofils 21 passgenau an die Hinterschnitte 6 des konturgebenden Elements 31 zumindest formschlüssig aneinander gefügt sind,
• – Erstarren der fließfähigen Spritzgussmasse 41 zu mindestens einem in den Hinterschnitten 13 des Faser-Thermoplast-Verbund-Hohlprofils 2 zur Ausbildung eines Funktionselements 42 und somit zu dem finalen Strukturelement 20,
• – Entformen des finalen Strukturelements 20 aus dem Werkzeug 10.

Another method for producing the structural element 20 from load introduction element 3 and fiber-thermoplastic composite hollow section 21 with thermoplastic matrix material
includes at least the following steps:

• - Insert the with at least one undercut 6 provided load introduction element 3 in the form of a contouring element 31 in the fiber-thermoplastic composite hollow section 21 for the formation of a structural element semifinished product 15 .
• - Local heating of the fiber-thermoplastic composite hollow profile 21 until the deformability of the fiber-thermoplastic composite hollow profile 21 in the area of the undercut of the contouring element 31 .
• - Inserting the structural element semifinished product 15 into a tool 10 where the sequence of said steps may be different,
• - Injection of the deformable fiber-thermoplastic composite hollow profile 21 with flowable injection molding compound 41 in the tool 31 in the area of the undercut of the contouring element 31 for the formation of at least one undercut 13 of the fiber-thermoplastic composite hollow profile 21 , where the formed undercuts 13 Fiber thermoplastic composite hollow profile 21 perfectly fitting to the undercuts 6 of the contouring element 31 at least positively connected to each other,
• - Solidification of the flowable injection molding compound 41 at least one in the undercuts 13 of the fiber-thermoplastic composite hollow profile 2 for forming a functional element 42 and thus to the final structural element 20 .
• - Removal of the final structural element 20 from the tool 10 ,

The load introduction element 3 can be within the fiber-thermoplastic composite hollow section 21 at the same time as a contouring and supporting element 31 or after its removal from the fiber-thermoplastic composite hollow section 21 as only contouring element 31 or contouring element or undercut form element are used.

• – wahlweise ein konturgebendes Element 31 mit mindestens einem Hinterschnitt 6, wobei das konturgebende Element 31 in das Faser-Thermoplast-Verbund-Hohlprofil 21 eingefügt ist,
• – zumindest einen im Hinterschnitt 6 des konturgebenden Elements 31 passgenau anliegenden Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 21 in formschlüssiger Verbindung in Form eines Struktur-Halbzeuges 15,
• – ein in den Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 21 eingreifendes und angespritztes Funktionselement 42, das aus einer unter Druck injizierten thermoplastischen Schmelze einer Spritzgussmasse 41 und nachfolgend erstarrten Spritzgussmasse 41 besteht,
• – wobei durch das Anspritzen 28 der geschmolzenen Spritzgussmasse 41 an den das Funktionselement 42 stützenden Hinterschnitt 13 eine form- und/oder stoffschlüssige Verbindung zwischen dem Hinterschnitt 13 des Faser-Thermoplast-Verbund-Hohlprofils 21 und dem erstarrten Funktionselement 42 ausbildet und sich damit ein finales Strukturelement 20 bildet.

The second structural element according to the invention 20 is at least a fiber-thermoplastic composite hollow section 21 with thermoplastic matrix material and a contouring element designed as a load introduction element 31 prepared according to an aforementioned method and further comprises

• - Optionally, a contouring element 31 with at least one undercut 6 , where the contouring element 31 in the fiber-thermoplastic composite hollow section 21 is inserted,
• - at least one undercut 6 of the contouring element 31 precisely fitting undercut 13 of the fiber-thermoplastic composite hollow profile 21 in positive connection in the form of a structural semi-finished product 15 .
• - one in the undercut 13 of the fiber-thermoplastic composite hollow profile 21 engaging and molded functional element 42 consisting of a pressure-injected thermoplastic melt of an injection molding compound 41 and subsequently solidified injection molding compound 41 consists,
• - Wherein by the injection molding 28 the molten injection molding compound 41 to the the functional element 42 supporting undercut 13 a positive and / or material connection between the undercut 13 of the fiber-thermoplastic composite hollow profile 21 and the solidified functional element 42 trains and thus becomes a final structural element 20 forms.

That in the undercut 13 of the fiber-thermoplastic composite hollow profile 21 solidified functional element 42 can serve as a pressure piece to support the trained positive connection.

The molded and solidified fitting 4 can as a functional element 42 be formed in the cavity 23 of the tool 10 is trained.

The contour-bound element 31 can be adjusted to the fiber-thermoplastic composite hollow profile in accordance with material and force flow 2 be connected.

The undercuts 6 and 13 can in terms of burden 29 of the final structural element 20 Be pronounced.

The injection molding compound 41 may have a low density.

The contouring element 31 can be thin-walled.

The functional element 42 Can be made locally with injection molding compound 41 be impressed.

The fitting 4 can as a functional element 42 be formed, wherein the functional element 42 in the area of the undercut 13 of the fiber-thermoplastic composite hollow profile 21 is injection-molded, so that at least one positive connection of the functional element 42 on fiber-thermoplastic composite hollow profile 21 is available.

The load introduction element 3 can be a contouring element 31 be and serve as a support element.

The contouring element 31 can be made of metal or plastic.

The contouring element 31 but also z. B. from sand or from a detachable / washable material and after the solidification of the functional element 42 from the fiber-thermoplastic composite hollow profile 21 be removed.

The 8th represents a first process step of the process for the production of the structural element 20 : Heating 26 of the FTV profile 21 in the area of the undercuts 6 of the inserted as a support element contour-bound element 31 where 8a a cross section BB with an outline insert 24 for forming the contour of the functional element 42 according to 8th shows.

In 9 is a second process step of the process for producing the structural element 20 : Insert 27 and positioning the heated structural element semifinished product 15 in the Anspritzhohlraum / the cavity 23 of the tool 10 shown.

The 10 shows a third essential process step of the process for producing the second structural element 20 : Injection 28 of the functional element 42 and forming the heated FTV hollow profile 21 in the undercuts 6 of the supporting contouring element 31 and training of the functional element 42 in the tool cavity 23 ,

To step 1:

It takes place according to 8th a local warming 26 fiber reinforced thermoplastic profile 21 in a heating zone 22 above the melting temperature of the thermoplastic 41 in the area intended for gating 19 on which the functional element 42 should be sprayed to allow the transformation. In this case, the use of various heating methods can come into question (eg hot gas, induction, infrared). That within the hollow profile 21 located contouring element 31 can either already at this moment in the Anspritzbereich 19 be positioned and heated with or in a subsequent step in the cold or heated state in the hollow section 21 be introduced.

Within the area intended for injection molding (cavity) 23 of the tool 10 can be a contour inserter 24 for the outer design of the second structural element 20 are located.

To step 2:

Position the profile 21 with the contouring element 31 in the injection mold 10 which is closed as in 9 is shown, and inserting the second structural element semifinished product 15 in the tool 10 , Thereafter, a closing (directional arrow 25 ) of the tool 10 to reach the operating state.

To step 3:

The molten injection molding compound 41 is, depending on the requirement kurzfaser-, long fiber or unreinforced, with or without filler, in the cavity 23 and on the still-molten fiber-thermoplastic composite (FTV) area 19 according to 10 injected. This is the heated fiber-thermoplastic composite profile 21 to the contouring with the undercuts 6 provided element 31 Pressed, the resulting undercuts 13 in the fiber-thermoplastic composite hollow profile 21 and the functional element 42 imaging tool cavity 23 be by means of the thermoplastic melt 41 filled. After the solidification of the melt 41 become the tool 10 opened, depending on the geometry of the functional element 42 possibly required tool contour inlay 24 removed and designed as a structural component 20 removed from the mold.

The structural element formed as a component 20 results from a combined automated production and position-variable positive and cohesive connection of thermoplastic functional elements 42 (Transmission components, levers, eccentrics, bearing seats) on endless fiber reinforced, endless or discontinuously produced hollow profiles 21 , The contouring element 31 is over an undercut contour 13 of the fiber-thermoplastic composite hollow profile 21 positive fit (and optionally additionally frictional or cohesive) with the hollow profile 21 to the structural element 20 connected. The expression of the undercuts 13 is due to the load in the application 29 customized.

The contouring element 31 can, depending on the nature, after the injection process in the component 20 stay or even be removed. A lasting contouring element 31 , z. B. in the form of a metal sleeve, supports the cross section of the profile 21 , as in 6 and 10 In addition, and improves the mechanical properties of the load introduction area. Depending on the loads that occur, the choice of the contouring element may result 31 the degree of lightweight can be increased.

In the manufacture and connection of a thermoplastic functional element 42 on a continuous fiber reinforced hollow structure 21 in a process step becomes the functional element 42 cohesively and, by at least one in the manufacturing process of the functional element 42 resulting undercut 13 , positive fit with the hollow profile 21 connected.

The fiber-reinforced thermoplastic profile (FTV profile) 21 the structural elements 20 consists of reinforcing fibers (eg carbon fibers, glass fibers, basalt fibers or natural fibers) and a thermoplastic matrix (eg PA, PPS, PEEK). The orientation of the fibers can be due to the loads 29 be adapted to the particular application. For predominantly tension and pressure loaded profiles 21 the reinforcing fibers are predominantly axially oriented and predominantly torsionally loaded profiles 21 the reinforcing fibers are predominantly oriented at a 45 ° angle. The profiles 21 can be continuous, z. As a pultrusion process, or discontinuously, for. B. a Schlauchblasverfahren be prepared. You can have a constant, but also one over the length of the profile 21 have varying cross-section.

The contouring element 31 is as a counter-tool for the defined formation of at least one undercut 13 in the fiber-thermoplastic composite hollow profile 21 necessary during forming. The geometry of the undercut 13 is freely selectable, but to the finished component 20 occurring loads 29 adapt. It can undercuts 13 be provided in axial, tangential or a combination of two directions. When designing the undercut geometry is the deformation potential of the fiber-thermoplastic composite profile 21 to take into account. Advantageously, the circumferential length of the deformed fiber-thermoplastic composite profile 21 equal to the circumferential length of the undeformed fiber-thermoplastic composite profile 21 so that this only has to be reshaped and not stretched or compressed. The contouring element 31 remains in a first preferred variant, as in 6 is shown in the finished component 20 and supports this in addition. For this purpose, it is advantageous, for. As a metallic hydroformed or one of a compared to the matrix of the fiber-thermoplastic composite profile 21 higher-melting plastic injection-molded plastic element to use. In a second preferred variant (not shown), the contouring element 31 be removed after the injection process, so that it in the finished component 20 no longer exists.

The molded functional element 42 , in case of 6 and 7 a gear, forms in the formed area an undercut contour, so that it both positive and cohesive with the fiber-reinforced thermoplastic fiber-thermoplastic composite profile 21 connected is. During the injection molding process, in the functional element 42 metallic functional surfaces (eg bushings) are integrated, previously in the injection molding tool 10 be inserted. In addition, the use of various injection moldable materials in a multi-component injection molding process is possible to improve the mechanical properties of the functional element 42 to adapt locally.

• – einer werkstoff- und kraftflussgerechten Anbindung des Funktionselementes 42 an das faserverstärkte Hohlprofil 21,
• – einer Anpassung der Ausprägung der Hinterschnitte 6, 13 an den Belastungszustand 29,
• – einem sehr hohen Leichtbaupotential mit einer geringen Dichte der Spritzgussmasse 41, mit einer Verwendung dünnwandiger oder nachträglich entfernbarer konturgebender Elemente 31, sowie mit angepassten Eigenschaften durch Mehrkomponentenspritzguss, wobei keine zusätzlichen Fügeelemente notwendig sind,
• – einer lokalen Aufdickung des Funktionselementsbereichs, so dass das volle Potenzial der ungestörten Tragstruktur genutzt werden kann,
• – einem stoffgleichen Strukturelement-System zumindest aus Funktionselement 42 und Hohlprofil 21 mit reduzierten zusätzlichen Herausforderungen in den Bereichen der Kontaktkorrosion sowie induzierten Spannungen in Folge von differierenden Wärmeausdehnungskoeffizienten.

The advantages of structural elements formed as a component 20 consist in

• - A material and power flow appropriate connection of the functional element 42 to the fiber-reinforced hollow profile 21 .
• - An adaptation of the expression of the undercuts 6 . 13 to the load condition 29 .
• - A very high lightweight potential with a low density of the injection molding compound 41 , with the use of thin-walled or subsequently removable contouring elements 31 , as well as with adapted properties by multi-component injection molding, whereby no additional joining elements are necessary,
• A local thickening of the functional element area, so that the full potential of the undisturbed supporting structure can be utilized,
• - A fabric-like structural element system at least from functional element 42 and hollow profile 21 with reduced additional challenges in the areas of contact corrosion as well as induced stresses due to different coefficients of thermal expansion.

• – einem Umformen des Hohlprofils 21 und Erzeugen des Funktionselements 42 in einem Prozessschritt,
• – einem Anspritzen der Funktionselemente 42 ohne Werkzeuganpassungen an beliebiger Stelle auf beliebig lange Hohlhalbzeuge,
• – einer Variierung der Ausprägung der durch den Anspritzprozess entstehenden Hinterschnitte 13 im Profil 21 ohne Anpassungen am Werkzeug 10, wobei nur das konturgebende Element 31 angepasst werden muss,
• – einer Verwendung von endlos und damit effizient herstellbaren Hohlprofil-Halbzeugen, einer hohen Automatisierbarkeit und einer gleichzeitigen Flexibilität bei der Integration von Funktionselementen 42 an die Hohlprofile 21.

The advantages of the method for producing the second structural element 20 consist in

• - A forming of the hollow profile 21 and generating the functional element 42 in a process step,
• - Injection of the functional elements 42 without tool adjustments at any place on hollow semi-finished products of any length,
• - A variation of the expression of the resulting by Anspritzprozess undercuts 13 In profile 21 without adjustments to the tool 10 , where only the contouring element 31 needs to be adjusted
• - A use of endless and thus efficiently producible hollow profile semi-finished products, high automation and a simultaneous flexibility in the integration of functional elements 42 to the hollow sections 21 ,

The invention relates to mostly cylindrical hollow structures in fiber-thermoplastic composite (FTV) construction with mostly metallic load introduction elements (LEE). Continuous fiber-reinforced hollow profiles with thermoplastic matrix material can be produced endlessly, energy-efficiently and thus cost-effectively in the pultrusion process, for example. The orientations of the endless reinforcing fibers can be adapted to the loads of the particular application. Such FTV hollow sections have, compared to metallic hollow sections, a very low mass and are ideal for the transmission of forces, torsional moments and possibly bending moments. They are basically suitable for many technical applications such as axles, shafts, pipes or hydraulic cylinders. For the introduction of loads in such hollow profiles are isotropic materials such as metals. The use of a thermoplastic matrix system for such hollow profiles allows local hot forming of the hollow profile after consolidation of the hollow profile during manufacture.

The present invention describes a method for the form-fitting (and possibly additionally positive and cohesive) acting connection between a mostly metallic load introduction element and a fiber-reinforced hollow profile for transmitting axial loads and / or torques and bending moments as well as structural elements produced by the method. The load introduction elements are characterized in particular by being attached to one or both ends of an arbitrarily long hollow profile.

The invention also relates to hollow structures consisting of a fiber composite with a thermoplastic matrix. They are basically suitable for many technical applications such as axles, shafts, pipelines and hydraulic cylinders. Such hollow structures can be produced, for example, in the pultrusion process continuously and energy-efficiently with a predefined fiber orientation. They can be kept as standard semi-finished products and then individually cut to length according to the respective application. The orientations of the endless reinforcing fibers can be adapted to the loads of the particular application. Such fiber-thermoplastic composite (FTV) structures have a very low mass compared to metallic structures and are outstandingly suitable for the transmission of forces and torsional moments and, if appropriate, bending moments. For the further technical use of such fiber-thermoplastic composite hollow structures are in many cases functional elements such. As gears, pulleys, bearing seats, levers or eccentric required, which can be easily and inexpensively integrate at any arbitrary length of the semifinished product at any position in the fiber-thermoplastic composite structure. The use of thermoplastic matrix systems for such hollow structures allows the local hot forming of the profile, creating novel, even form-fitting connection possibilities are created.

LIST OF REFERENCE NUMBERS

1

Structural element for load introduction

2

Fiber-reinforced plastic hollow profile / fiber thermoplastic composite hollow profile

3

Load introduction element

31

Contoured element / Contour element

4

fitting

41

injection molding compound

5

External surface of the load introduction element

6

Undercut of the load introduction element

7

Sleeve / reinforcing sleeve

8th

Outer surface of the injection molding

9

connecting region

10

Tool / tool injection molding compound

11

forming region

12

outside

13

Undercut of the fiber-plastic composite hollow profile

14

additional location

15

Structural element semifinished

16

Second connection area

17

Kavitätsleitung

18

injection unit

19

To be sprayed area of the fiber-plastic composite hollow profile

20

Second structural element for functions

21

Second fiber-plastic composite hollow profile

22

heating zone

23

Anspritzkavität inside the tool

24

contour depositors

25

Closing direction of the two tool parts

26

Step heating

27

Step insert

28

Step injecting

29

burden

30

Hollow section axis

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 102004038082 B4 [0002]
• GB 2160144 A [0003]
• DE 102010041790 A1 [0004]
• DE 102006039565 A1 [0005]
• DE 10249591 A1 [0005]
• DE 102004021144 A1 [0005]
• JP 2004291505 A [0005]
• DE 102008057893 A1 [0006]
• DE 202008008821 U1 [0006]
• WO 2005/105417 A1 [0007]
• EP 0311837 B1 [0008]
• DE 102012020184 A1 [0009]
• DE 102011108219 A1 [0010]
• DE 102009056472 A1 [0012]
• DE 102007060628 A1 [0013]
• DE 10014332 A1 [0014]
• DE 102006010271 A1 [0015]
• DE 102007017414 A1 [0016]
• DE 102006038930 A1 [0017]
• DE 19538360 C1 [0019]

Claims (19)

Process for the production of structural elements ( 1 ) from load introduction element ( 3 ) and fiber-plastic composite hollow profile ( 2 ) comprising thermoplastic matrix material, comprising at least the following steps: - insertion of the at least one undercut ( 6 ) load introduction element ( 3 ) in the fiber-plastic composite hollow profile ( 2 ) for forming a structural element semifinished product ( 15 ), - local heating of the fiber-plastic composite hollow profile ( 2 ) to the deformability of the fiber-plastic composite hollow profile ( 2 ) in the area of the undercut ( 6 ) of the load introduction element ( 3 ), - inserting the structural element semifinished product ( 15 ) into a tool ( 10 ), wherein the aforementioned method steps are optionally carried out differently in their sequence, - injection molding of the deformable fiber-plastic composite hollow profile ( 2 ) with flowable injection molding compound ( 41 ) in the tool ( 10 ) in the region of the undercut of the load introduction element ( 3 ) for the formation of at least one undercut ( 13 ) of the fiber-plastic composite hollow profile ( 2 ), wherein the formed undercuts ( 13 ) Fiber-plastic composite hollow sections ( 2 ) to the undercuts ( 6 ) of the load introduction element ( 3 ) are joined together at least in a form-fitting manner, solidification of the flowable injection molding compound ( 41 ) to at least one in the undercuts ( 13 ) of the fiber-plastic composite hollow profile ( 2 ) for forming a fitting ( 4 ) and thus to the final structural element ( 1 ), - demolding the final structural element ( 1 ) from the tool ( 10 ). Method for producing a structural element ( 20 ) from load introduction element ( 3 ) and fiber-plastic composite hollow profile ( 21 ) comprising thermoplastic matrix material, comprising at least the following steps: - insertion of the at least one undercut ( 6 ) load introduction element ( 3 ) in the form of a contouring element ( 31 ) in the fiber-plastic composite hollow profile ( 21 ) for forming a structural element semifinished product ( 15 ), - local heating of the fiber-plastic composite hollow profile ( 21 ) to the deformability of the fiber-plastic composite hollow profile ( 21 ) in the region of the undercut of the contouring element ( 31 ), - inserting the structural element semifinished product ( 15 ) into a tool ( 10 ), wherein the aforementioned method steps are optionally carried out differently in their sequence, - injection molding of the deformable fiber-plastic composite hollow profile ( 21 ) with flowable injection molding compound ( 41 ) in the tool ( 31 ) in the area of the undercut of the contouring element ( 31 ) for the formation of at least one undercut ( 13 ) of the fiber-plastic composite hollow profile ( 21 ), wherein the formed undercuts ( 13 ) Fiber-plastic composite hollow sections ( 21 ) to the undercuts ( 6 ) of the contouring element ( 31 ) are joined together at least in a form-fitting manner, solidification of the flowable injection molding compound ( 41 ) to at least one in the undercuts ( 13 ) of the fiber-plastic composite hollow profile ( 2 ) trained functional element ( 42 ) and thus to the final structural element ( 20 ), - demolding the final structural element ( 20 ) from the tool ( 10 ). A method according to claim 1 or 2, characterized in that by the primary forming of the fiber-plastic composite hollow profile ( 2 . 21 ) depending on the coordination of the process parameters and the geometry of the load introduction element ( 2 ) only one contact point of the two joining partners is achieved, wherein after applying a mechanical load ( 29 ) due to elastic strains a cavity at the contact point and a bias voltage is formed, wherein in a further step, an injection of flowable injection molding material ( 41 ) is produced at high pressure in the contact point a joint pressure corresponding to the bias and wherein the resulting intermediate layer, the fiber-plastic composite hollow profile ( 2 . 21 ) and the load introduction element ( 3 ) isolated from each other and prevents electrochemical corrosion. A method according to claims 1 to 3, characterized in that the load application element ( 3 ) within the fiber-plastic composite hollow profile ( 2 . 21 ) as a contouring and supporting element ( 31 ) or after its removal from the fiber-plastic composite hollow profile ( 21 ) as only contouring element ( 31 ) is used. Process according to claims 1 to 4, characterized in that the undercuts ( 6 . 13 ) in the axial direction to the hollow profile axis ( 30 ) and / or formed in the circumferential direction. Structural element ( 1 ), at least comprising a fiber-plastic composite hollow profile ( 2 ) with thermoplastic matrix material and produced by a method according to one of claims 1 to 5, characterized in that it further comprises - a load introduction element ( 3 . 31 ) with at least one undercut ( 6 ), wherein the load introduction element ( 3 ) in the fiber-plastic composite hollow profile ( 2 ), - at least one in the undercut ( 6 ) of the load introduction element ( 3 ) precisely fitting undercut ( 13 ) of the fiber-thermoplastic composite hollow profile ( 2 ) in positive connection in the form of a structural semi-finished product ( 15 ) - one in the undercut ( 13 ) of the fiber-thermoplastic composite hollow profile ( 2 ) engaging and molded molding ( 4 ), which consists of a melt injected under pressure and subsequently solidified injection molding compound ( 41 ), wherein - by injecting ( 28 ) of the molten injection molding compound ( 41 ) to which the fitting ( 4 ) supporting undercut ( 13 ) a positive or material connection between the undercut ( 13 ) of the fiber-plastic composite hollow profile ( 2 ) and the solidified molding ( 4 ) and thus a final structural element ( 1 ) arises. Structural element ( 20 ), at least from a fiber-plastic composite hollow profile ( 21 ) with a thermoplastic matrix material and a contouring element designed as a load introduction element ( 31 ), produced according to a method according to one of claims 2 to 5, characterized in that it further comprises - optionally a contouring element ( 31 ) with at least one undercut ( 6 ), whereby the contouring element ( 31 ) in the fiber-plastic composite hollow profile ( 21 ), - at least one in the undercut ( 6 ) of the contouring element ( 31 ) precisely fitting undercut ( 13 ) of the fiber-plastic composite hollow profile ( 21 ) in positive connection in the form of a structural semi-finished product ( 15 ), - in the undercut ( 13 ) of the fiber-plastic composite hollow profile ( 21 ) engaging and molded functional element ( 42 ), which consists of a pressure-injected and subsequently solidified injection molding compound ( 41 ), wherein - by injecting ( 28 ) of the molten injection molding compound ( 41 ) to which the functional element ( 42 ) supporting undercut ( 13 ) a positive and / or material connection between the undercut ( 13 ) of the fiber-plastic composite hollow profile ( 21 ) and the solidified functional element ( 42 ) and thus forms a final structural element ( 20 ). Structural element according to claims 6 or 7, characterized in that in the undercut ( 13 ) of the fiber-plastic composite hollow profile ( 2 . 21 ) solidified fitting ( 4 ) or solidified functional element ( 42 ) serves as a pressure piece to support the formed positive connection. Structural element according to claim 6, characterized in that the molded-on and solidified shaped piece ( 4 ) as a functional element ( 42 ) formed in the cavity ( 23 ) of a tool ( 10 ) is trained. Structural element according to claim 6 or 7, characterized in that the load introduction element ( 3 ) and the contour-bound element ( 31 ) suitable for material and force flows to the fiber-plastic composite hollow profile ( 2 ) are connected. Structural element according to claim 6 or 7, characterized in that the undercuts ( 6 . 13 ) in terms of load ( 29 ) of the final structural element ( 1 . 20 ) are pronounced. Structural element according to claim 6 or 7, characterized in that the injection molding compound ( 41 ) is made of thermoplastic or fiber reinforced thermoplastic and has a low density. Structural element according to claim 6 or 7, characterized in that the load introduction element ( 3 ) and the contouring element ( 31 ) are thin-walled. Structural element according to claim 6, characterized in that with a relatively smooth surface of the fiber-plastic composite hollow profile ( 2 ) at least one of the areas of the molded undercuts ( 13 ) reinforcing sleeve ( 7 ) around the fitting ( 4 ) is attached. Structural element according to claim 5 or 7, characterized in that the shaped piece ( 4 ) and the functional element ( 42 ) locally with injection molding compound ( 41 ) are sprayed. Structural element according to claim 7, characterized in that the shaped piece ( 4 ) as a functional element ( 42 ), wherein the functional element ( 42 ) in the area of the undercut ( 13 ) of the fiber-plastic composite hollow profile ( 21 ) is injection molded, so that at least one positive connection of the functional element ( 42 ) on the fiber-plastic composite hollow profile ( 21 ) is available. Structural element according to claim 7, characterized in that the load introduction element ( 3 ) as a contouring element ( 31 ) and serves as a support element. Structural element according to claim 6 or 7, characterized in that the load introduction element ( 3 ) and the contouring element ( 31 ) of solid material, preferably of metal or plastic. Structural element according to claim 7, characterized in that the contouring element ( 31 ) is made of sand or of another detachable / washable substance and after solidification of the functional element ( 42 ) from the fiber-plastic composite hollow profile ( 21 ) is removable.

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