DE102010030484A1 - Strut element e.g. hinged support, for coupling end pieces for receiving e.g. elastomeric joint, in automotive industry, has end part comprising conical cross-section extending beyond outer contour in connecting region - Google Patents

Abstract

The element has a tubular strut section (1) formed of a fiber-reinforced matrix. An end portion is provided for force application. The strut section and the end part are firmly connected together. The strut section and the end part are connected together in an overlapping manner. The end part comprises an axially conical cross-section extending beyond an outer contour in a connecting region through an inner area of the strut section. A cross-section of the strut section and the end part are circularly formed in the connection region. The matrix material is made of thermoplastic resin. An independent claim is also included for a method for manufacturing a strut element.

Description

The invention relates to a fiber-reinforced strut element for coupling connection of two assemblies, with a strut region and a connection region with bearing support, according to the preamble of claim 1. The invention further relates to a method for producing a strut element according to claim 10.

Strut elements, by which various components or assemblies are interconnected, are known from the prior art. It may be rigid struts such as scaffold struts or floor supports, which are arranged substantially immovable between components and thereby prevent relative movements of the components to each other.

Likewise known from the prior art are movable strut elements such as coupling supports or pendulum supports, which are connected at one end or at both ends at least slightly movable or articulated to the corresponding connection components or assemblies, for example, to couple the connection components with respect to a degree of freedom of movement ,

Especially in vehicle high demands are placed on such strut elements, including above all high load capacity and fatigue strength at the lowest possible mass, and at the same time low production costs. This applies first of all regardless of the structural embodiment and of the materials from which such struts are made.

From the state of the art, one-piece struts made of steel, light metals or plastics are first of all known. Among them, the struts made of steel primarily have the disadvantage of relatively high weight, whereas struts made of light metals are relatively expensive in production. In both cases, however, are often required, complex geometries of the end portions of the struts for connection to the adjacent components - for example, end pieces for receiving elastomer or ball joints - comparatively complex and therefore costly to manufacture.

One-piece struts, such as pendulum supports, made of plastics, however, usually have the disadvantage that for each strut length (as well as for each variation in the strut ends) specially a relatively complex tool for the Urformung must be created. In particular, in plastic struts, it is also often desirable to manufacture the strut portion between the end portions of the strut of a material with special properties, such as unidirectionally long fiber reinforced plastic, while the end pieces z. B. made of solid materials or short fiber reinforced materials.

With this background, there are approaches in the art to connect strut end pieces or end heads to separately manufactured strut spacers. In this way, specialized materials for the different tasks of the strut section and the end heads can be used. In addition - in the sense of a cost-effective modular system - struts with different lengths from appropriately cut strut sections and from each identical end pieces can be assembled.

In such known from the prior art, built struts, however, the production of the usual for connecting cut-to-length strut sections with corresponding strut end pieces welded joint - due to the high load on the connecting portion between strut section and tail - generally consuming and therefore expensive.

From the DE 10 2004 042 964 A1 is a built plastic strut with a blow-molded strut region made of plastic, in which the end pieces for the introduction of force (eg ball joint shells) are manufactured separately and then positively, adhesively and / or materially connected to the ends of the blow-molded strut region. In this known plastic strut, however, different production tools, in particular suitable blow molds, are required to produce struts of different lengths. In addition, the (usually particularly highly loaded) connecting areas between the ends of the blow-molded strut area and the struts end pieces in this prior art relatively small cross-sectional areas, but which take over the entire force into the strut area, as well as the permanently secure connection between the strut area and tail have to.

With this background, it is an object of the present invention to provide a strut element and a method for producing the same, with the aforementioned limitations and disadvantages existing in the prior art to be overcome. The strut element according to the invention should - at a cost-effective production - first connect a particularly low mass with a high strut rigidity simultaneously. In addition to strive with little constructive and production-side effort Different lengths and possibly different tail can be displayed. In any case, however, a defined, high-strength connection between strut element and tail should be achieved.

This object is achieved by a strut element with the features of claim 1 and by a method according to claim 11. Preferred embodiments are subject of the dependent claims.

In itself initially known manner, the strut element for coupling connection of two modules, and comprises at least one substantially tubular strut portion of a fiber-reinforced matrix and at least one cohesively connected to the strut portion end piece for introducing force into the strut element.

According to the invention, however, the strut element is characterized in that strut portion and tail are arranged overlapping in the connection region, wherein the end piece in the connecting region with the strut portion has an outer contour extending in the axial direction - beyond the inner cross section in the strut region of the strut portion addition.

This means, first of all, that the joining of the strut section and end piece - due to the conically widened end portion in the connection area - results in a defined contact of strut section and end section in the connection area, by the end of the strut section corresponding to the conically shaped end section beyond its original inner cross section is widened, and so defined at the tail comes to flat contact. In other words, the widening of the strut section end results in a reliably reproducible radial contact force between the end of the strut section and the end section of the strut element which is conically shaped in the connection region.

The invention is in principle initially realized independently of which cross-sectional shape strut section and tail in the connection area and in which way the cohesive connection between strut section and tail, as long as the inner cross section of the strut section when joining with the tail undergoes the required to produce the defined system expansion , Thus, the connection between the strut section and tail can be done for example by means of gluing.

According to a particularly preferred embodiment of the invention, however, the cross sections of strut portion and tail in the connection area are circular and rotationally friction welded together. This embodiment has the advantage of particularly simple manufacturability, in particular of the strut section, for example in the form of a tubular semifinished product. At the same time results from the connection of strut section and tail by rotational Reibverschweißung in the region of the conical contact surface between the strut section and tail a high-strength connection, compared to a bond in particular in a simple manner and - due to the attributable curing time - while minimizing the time required for production can be.

Preferably strut section and tail essentially comprise the same matrix material, which results in a particularly intimate cohesive connection between the strut section and tail, in particular in their Reibverschweißung. In addition, a thermoplastic material is preferably selected as the matrix material, since optimum welding results are achieved in this way. Furthermore, a thermoplastic plastic, in particular in the strut section, permits a problem-free widening of the strut section end in the connection region by means of the conically shaped region of the end piece.

A further particularly preferred embodiment of the invention provides that the strut section contains longitudinally arranged long fibers. In this way maximum rigidity of the strut element according to the invention is achieved at the same time extremely low weight.

In contrast to the aforementioned, known from the prior art embodiments of a welded joint between strut section and tail can be thanks to the invention also - thanks to the overlap and defined mutual investment - even with a purely longitudinal arrangement of the reinforcing fibers in the strut a high-strength connection between the Achieving strut section and the tail.

In general, the invention allows due to the simple, substantially tubular design of the strut element (in the sense of a modular system) a cost-effective representation of strut elements in virtually any length and with different connection options, as this simply each connected the desired end pieces with a correspondingly cut from a continuous material strut section Need to become. As semi-finished for cutting and thus generating the strut sections can be used in particular an endless drawn tube.

Another, alternative embodiment of the invention provides that the strut portion is formed by an extruded tube. This embodiment offers a cost-effective way of producing in particular shorter strut elements.

The invention can be realized largely independent of the shape and function of the end pieces, which can be represented with the invention both strut elements with rigid connection to the respective connection components as well as strut elements with movable or articulated connection.

With the background of the provision of a strut element with a movable connection, for example a pendulum support, further preferred embodiments of the invention therefore provide that the at least one end piece of the strut element has a joint receptacle, or that the at least one end piece is formed integrally with a ball joint socket.

Thanks to these embodiments, particularly compact, cost-effective and low-mass designs, in particular for pendulum supports, in which the connection to the connection components of the strut element by means of ball joints. The ball joints in particular a pendulum support can thus be mounted directly into the end pieces of the strut element, or the end pieces of the strut element can even form the spherical shells for the respective ball joints of the pendulum support itself.

A further particularly preferred embodiment of the invention provides that a peripheral projection for abutment of the axial end of the strut portion is arranged on the end piece. In this case, according to a possible embodiment, the circumferential projection may also have a substantially hook-shaped cross section. The circumferential projection generally leads to a defined also in the axial direction conditioning between the strut section and tail, and thus to a high dimensional accuracy with respect to the length of the strut element to be produced, as well as to a more controllable and reproducible welding of strut section and tail.

In addition, if the circumferential projection also has a substantially hook-shaped cross-section, this also results in a sealing of the welding gap, which is otherwise open at the end of the strut section, between the strut section and end piece. This counteracts the penetration of welding expulsion, which benefits a better defined Reibverschweißung as well as a better appearance of the finished welded joint.

The invention further relates to a method for producing a strut element, for example a pendulum support. In this case, the strut element to be produced comprises at least one substantially tubular strut section and at least one end piece for introducing force, wherein the end piece has an outer contour that widens conically beyond the original inner diameter of the strut section in the connection region with the strut section.

The method according to the invention comprises the method steps described below.

First, in a first method step, a relative rotation of the strut section and tail against each other about the longitudinal axis of the strut section is initiated. Subsequently, in a further method step, an axial merging or compressing of strut section and end piece takes place along the longitudinal axis of the strut section.

In this case, the strut portion is heated in the connection area with the end piece due to the contact friction by the mutual rotation, and at the same time - due to the conical contour of the end piece in the connection area - exactly widened to the tail. Subsequently, the relative rotation between the strut portion and tail is terminated, wherein forms a friction-welded connection between the strut portion and tail in the connecting region due to the friction heating. Finally, after a short cooling phase for the friction-welded connection, the axial pressing pressure between the strut section and the end section is removed, after which the friction-welded connection is finished or the finished strut element is obtained.

A preferred embodiment of the method according to the invention further provides that - in the step of axially compressing the relatively rotating parts "strut section" and "tail" along the outer circumference of the strut section in the connecting region with the tail a passive support tool is positioned. In this case, the strut section is supported in a radially outward-pointing direction on the support tool.

As a result, the contact pressure between the end of the strut section and the tail in the transition region or welding area can be controlled even better or increased in a controlled manner, resulting in a Accordingly, even more intensive welding of strut section and tail results. Since, in the welding, the actual contact pressure between the strut section and the end piece is established by the conical contour of the end section in cooperation with the axial compression of the strut section and end section, it suffices for the support of the connection section or the welding section in this embodiment of the invention to be passive acting support tool.

In the following the invention will be explained in more detail with reference to exemplary embodiments illustrative drawings. Showing:

1 in a schematic sectional view of a strut section for a strut element according to the invention;

2 in a 1 corresponding representation of an end piece for a strut element according to the invention; and

3 two embodiments of a strut element according to the invention in each case in half section above or below the center line.

1 and 2 show in longitudinal section a strut section 1 and a tail 2 for a strut element according to the invention. One recognizes the simple construction of the tail 2 as well as in particular the strut element 1 , The strut element is formed in the illustrated embodiment by a straight tube whose wall 3 Here consists of a particular unidirectional long fiber reinforced thermoplastic matrix.

The tail 2 owns in the connection area 4 a rotationally symmetrical conical outer contour, while the contour in the connection area 5 (For rigid or articulated connection of the strut element with corresponding connection components) can be designed largely arbitrary. In the illustrated embodiment, the tail 2 in the connection area 5 as an example a simple through hole 6 on, for example, for receiving the ball stud of a (not shown) ball joint.

3 shows one of the two ends of a strut element according to the invention in two different embodiments, which the upper half-section A and the lower half-section B of in 3 form longitudinal section shown. It can be seen that the illustrated embodiments each have an initially tubular strut section 1 as well as in 3 already with the strut section 1 connected tail 2 include.

The connection between the strut section 1 and the tail 2 in the connection area 4 takes place by rotary friction welding, by strut section 1 and tail 2 along the common longitudinal axis of the strut element relative to each other in rotation and simultaneously moved by means of an axial force F _{A to} each other. The in the connection area 4 conical contour of the tail 2 deviates by frictional heat the matrix material of the strut section 1 in the connection area 4 on, so that on the one hand a conical widening of the strut section 1 in the connection area 4 results, wherein the frictional heat simultaneously to a softening of the matrix material of strut section 1 and / or the material of the tail 2 leads.

The radial expansion of the strut section 1 in the connection area 4 leads to a surface-acting, radial contact force F _R between the wall 3 of the strut section 1 and the conically shaped outer contour of the tail 2 in the connection area 4 , whereby a well-defined plant of wall 3 and tail 2 in the connection area 4 , And thus a particularly good controllable welding is obtained.

The in the two half-sections A, B according to 3 (Above or below the axial center line) contained embodiments of the strut element according to the invention differ in each case by a further feature of the embodiment according to 1 and 2 , This further feature relates to the embodiments according to 3 one each - still in the rotationally symmetrical connection area 4 the conical outer contour of the tail arranged - circumferential stop projection 7 respectively. 8th ,

The stop tab 7 respectively. 8th on the one hand ensures a relative position of strut section defined in the axial direction 1 and tail 2 during welding in the connection area 4 , On the other hand, by the stop projection 7 respectively. 8th the escape of welding expulsion during the welding of strut section 1 and tail 2 limited or prevented, the latter in particular by the stop projection 8th with a hook-shaped cross-section which almost completely encloses or stops any sweaty discharge.

The design of the end piece 2 in the connection area 5 (For rigid or articulated connection of the strut element with corresponding connection components) finally can be chosen practically arbitrary. In particular, it is not required that the connection area 5 of the tail 2 - like the connection area 4 - Is also rotationally symmetrical. So can in the connection area 5 of the tail 2 for example (like represented) a through hole 6 z. B. arranged to receive the ball stud of a ball joint or to receive an elastomeric bearing. The connection area 5 of the tail 2 However, it is also possible for example to form the ball socket of a ball joint by itself, so that in this respect no further components are required.

The reference number 9 designated in 3 an example of a - here only schematically indicated - preferably axially divided into two support tool. The support tool 9 serves the support of the rotational welding between strut section 1 and tail 2 initially softened and simultaneously widened end of the strut section 1 in the connection area 4 , For this purpose, the support tool 9 one with the desired outer contour of the strut section 1 in the connection area 4 matching, conical inner contour in the connection area 4 on. This way, the wall becomes 3 of the strut section 1 additionally supported in the rotation welding on the outside, whereby the height of the radial contact force F _R and thus the properties and the quality of the weld joint between strut section 1 and tail 2 even better controllable or reproducible.

As a result, it is clear that with the invention, a cost-producible strut element and a method for its production is provided, wherein the strut element combines high rigidity and fatigue strength at the same time very low mass. The strut element can be finished in virtually any length dimensions without redesign and without significant tool changes. In contrast to the state of the art, the high-strength and at the same time cost-producible weld connection between the strut section and the end piece of the strut element can be produced in a very short time and with closely reproducible properties.

The invention thus makes a contribution to the cost-effective production of lightweight and stiff strut elements, which can be provided in terms of an effective, cost-effective modular system in a variety of lengths and connection variations.

LIST OF REFERENCE NUMBERS

1

strut portion

2

tail

3

Strebenwandung

4

connecting area

5

terminal area

6

Joint socket, ball joint socket

7, 8

stop projection

9

support tool

F _A

axial force

F _R

Radial force, expansion force

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 102004042964 A1 [0009]

Claims (12)

Strut element for coupling connection of two assemblies, the strut element comprising at least one substantially tubular strut portion ( 1 ) of a fiber-reinforced matrix and at least one end piece ( 2 ) for force introduction, wherein strut section ( 1 ) and tail ( 2 ) are materially interconnected, characterized in that strut section ( 1 ) and tail ( 2 ) in the connection area ( 4 ) are arranged overlapping, wherein the tail ( 2 ) in the connection area ( 4 ) an axially substantially conically over the inner cross section in the strut region of the strut portion ( 1 ) has widening extending outer contour addition. Strut element according to claim 1, characterized in that the cross sections of strut section ( 1 ) and tail ( 2 ) in the connection area ( 4 ) are formed circular and are rotationally friction welded together. Strut element according to claim 1 or 2, characterized in that strut section ( 1 ) and tail ( 2 ) comprise substantially the same matrix material. Strut element according to claim 3, characterized in that the matrix material is a thermoplastic material. Strut element according to one of claims 1 to 4, characterized in that the strut section ( 1 ) contains longitudinally arranged long fibers. Strut element according to one of claims 1 to 5, characterized in that the strut section ( 1 ) is formed by an extrusion tube. Strut element according to one of claims 1 to 6, characterized in that the end piece ( 2 ) a joint recording ( 6 ) having. Strut element according to one of claims 1 to 6, characterized in that the end piece ( 2 ) in one piece with a ball joint socket ( 6 ) is trained. Striving element according to one of claims 1 to 8, characterized in that the end piece ( 2 ) a circumferential projection ( 7 . 8th ) for abutment of the axial end of the strut portion ( 1 ) is arranged. Strut element according to claim 9, characterized in that the circumferential projection ( 8th ) has a substantially hook-shaped cross-sectional shape. Method for producing a strut element, for example a pendulum support, the strut element comprising at least one substantially tubular strut section (US Pat. 1 ) and at least one tail ( 2 ) for the introduction of force, wherein the tail ( 2 ) in the connection region with the strut section ( 1 ) is substantially conical over the original inner diameter of the strut portion (FIG. 1 ) extending outward outer contour, the method comprising the method steps: a. Introduction of relative rotation between strut section ( 1 ) and tail ( 2 ) about the longitudinal axis of the strut portion ( 1 ); b. Axial compression (F _A ) of strut section (FIG. 1 ) and tail ( 2 ) along the longitudinal axis of the strut section ( 1 ) under frictional heating and expansion (F _R ) of the strut section ( 1 ) in the connection area ( 4 ) with the tail ( 2 ); c. Terminating the relative rotation between strut section ( 1 ) and tail ( 2 ) while forming a friction-welded connection between the strut section (FIG. 1 ) and tail ( 2 ) in the area of the wall ( 3 ); and d. Termination of axial compression (F _A ) of strut section (FIG. 1 ) and tail ( 2 ). A method according to claim 11, characterized in that in method step b) along the outer circumference of the strut portion ( 1 ) at least in the connection area ( 4 ) with the tail ( 2 ) a strut section ( 1 ) radially passive supporting support tool ( 9 ) is positioned.

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