DE102016215938B4 - Method for producing a leaf spring, and leaf spring and chassis for a motor vehicle - Google Patents

Abstract

Method for producing a leaf spring (1; 15; 18) from a fiber composite material, wherein the leaf spring (1; 15; 18) consists of a plurality of fiber layers (9 to 14) with at least one thickening (2) extending longitudinally between ends (4, 5) 3), wherein the at least one thickening (2, 3) is defined in each case by at least one insert (8), which is prefabricated as a unit and subsequently in the region of the respectively defined thickening (2, 3) between an upper cover layer (6; 16; 19) and a lower cover layer (7; 17; 20) is arranged, and the at least one thickening (2, 3) is respectively formed by a plurality of intermediate inserts (8), characterized in that corresponding inserts ( 8) are arranged mirrored to each other.

Description

The invention relates to a method for producing a leaf spring made of a fiber composite material, wherein the leaf spring is made of several fiber layers with at least one lying in the longitudinal direction between the ends thickening. Furthermore, the invention relates to a leaf spring and a chassis for a motor vehicle.

Such a method or such a leaf spring is from the WO 2014/145585 A1 known. It is proposed to use a single separate insert in a leaf spring made of fiber-reinforced plastic.

From the EP 0 134 617 A1 is also known a leaf spring made of fiber-reinforced plastic, wherein a single core element of the leaf spring extends over the entire length of the leaf spring.

Of the US 4,725,074 A is a leaf spring made of fiber reinforced plastic to refer to, which has local thickening. Notes on how to make this leaf spring and its thickening, but can not be found in this document.

Of the FR 2 587 649 A1 is to take a leaf spring with integrated pipe sections that locally increase the thickness of the leaf spring. From the DE 82 26 274 U1 is known a resilient slot closure wedge laying down windings in grooves of an electric machine.

Finally, out of the DE 10 2010 002 988 A1 a fiber composite profile component, for example in the formation of a leaf spring known, wherein thickening means of several inserts are realized.

In chassis of motor vehicles leaf springs can be used as suspension springs, which support the construction of the vehicle resiliently with respect to the wheels provided on the wheel carriers. A significant advantage of a leaf spring is that it also act as a construction element for connecting structure and axle and can take over Radführungsfunktionen compared to other types of spring simultaneously. If a plurality of leaf springs are then used, a certain degree of damping can still be achieved due to the frictional forces between the individual spring leaves, so that the leaf springs can support the work of a vibration damper.

Leaf springs are now increasingly made of a fiber composite material, which can realize the advantages mentioned above with low weight. Usually, the leaf spring is composed of several fiber layers, which are positioned according to the desired design of the leaf spring to each other, compacted and then bonded together by a plastic matrix materially. Depending on the geometry and choice of material of this ultimately formed leaf spring can thereby realize different properties of the leaf spring.

From the DE 10 2010 050 065 B4 is a method for producing a leaf spring made of a fiber composite material, wherein the leaf spring is made of several fiber layers. In this case, between the ends of the leaf spring, a thickening is designed with a greater thickness compared to the remaining part of the leaf spring, this thickening being produced by fiber layers of different lengths each extending alternately from the ends into the desired region and overlapping here. This targeted overlap of the fiber layers in the desired area then causes the thickening there.

Starting from the above-described prior art, it is now the object of the present invention to provide a method for producing a leaf spring made of a fiber composite material, wherein it should be possible to produce at least one thickening with low production costs.

This object is achieved on the basis of the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims give each advantageous embodiments of the invention. A leaf spring according to the invention is also the subject of claim 7, while a leaf spring having a landing gear claimed in claim 8.

According to the invention, in a method for producing a leaf spring made of a fiber composite material, the leaf spring is manufactured from a plurality of fiber layers with at least one longitudinal thickening between the ends. According to the invention, the leaf spring is thus made of a plurality of individual fiber layers, which form a fiber-plastic composite in combination with a plastic. For the purposes of the invention, the fibers are reinforcing fibers, in particular in the form of glass fibers, which are surrounded by a plastic matrix. The plastic matrix is preferably formed by a thermosetting plastic, which may be in the form of epoxy resin.

In the case of the leaf spring to be produced, at least one thickening is formed in the course of production between the ends. Here is under a "thickening" to understand a portion of the leaf spring, which is compared to other sections of the leaf spring with a significantly larger thickness, ie a greater extension in the compression direction, executed. Along the longitudinal extent of the leaf spring one or more such thickened areas may be provided, which may be designed according to their thickness in accordance with or deviating.

The invention now includes the technical teaching that the at least one thickening is defined in each case by at least one insert, which is prefabricated as a unit and subsequently arranged in the region of the respectively defined thickening between an upper cover layer and a lower cover layer. In other words, in the method according to the invention, at least one insert is already manufactured in advance, wherein this prefabricated insert is then placed between a lower and an upper cover layer in the area to be thickened in the further production process of the actual leaf spring and, after connection with the cover layers there, the desired one Thickening defined.

Such a design of a method has the advantage that the production costs can be reduced by the upstream production of the at least one insert. Because the actual leaf spring is thus divided into several components, which are merged only at the end of the manufacturing process. In this way, positioning and connection of the individual fiber layers can be made simpler in the inserter than would be the case if fiber layer for fiber layer were laid one on top of the other in an expiration to the final leaf spring. As a further advantage, a production of leaf springs can thereby be designed in a modular manner, in that different combination possibilities of prefabricated embodiments of inserts with different cover layers exist and thus also different properties of leaf springs can be realized. In addition, different prefabricated inserts could be combined with each other. Overall, the manufacture of a leaf spring can be made simple by arranging one or more prefabricated inserts between the cover layers at or the respective points and thereby one or more thickened areas are realized.

In contrast, in the case of DE 10 2010 050 065 B4 a respective thickening of a leaf spring to be manufactured by realizing a corresponding overlap of fiber layers designed, which each extend alternately from axial ends of the leaf spring forth in the corresponding area. This is correspondingly complicated, since for the production fiber layer for fiber layer must be stacked on top of each other and slippage of the individual layers before the final joining is to be prevented.

The fact that the at least one insert is "prefabricated as unit" means, for the purposes of the invention, that the insert has already been produced in the course of an upstream production process as a fiber-plastic composite. Preferably, the individual fiber layers of the insert are precompacted in a furnace process and incorporated in a plastic matrix.

In principle, depending on the properties of the final leaf spring to be achieved, the insert can be made of the same fiber composite material as the cover layers or also of a material to be deviated. Likewise, the cover layers may consist of one and the same material or be formed by different materials.

According to one embodiment of the invention, the at least one insert is in advance composed of a plurality of fiber layers, which are connected in overlapping manner in at least one section and thereby define a greater thickness in the respective section. In a further development of this embodiment, fiber layers of different lengths are connected to one another. The at least one insert is thus composed according to a predefined pattern of the different fiber layers, wherein the thickness to be achieved is realized by targeted overlapping of the different fiber layers.

According to an alternative or supplementary embodiment of the invention, the at least one insert is previously composed of several fiber layers, wherein at least one section is made of greater thickness by attaching at least one shorter fiber layer to at least one longer fiber layer. In this case, therefore, the desired thickness of the at least one inserter is realized in that one or more shorter fiber layers are placed on one or more longer fiber layers. The fibers are thus stacked on top of each other.

According to a further embodiment of the invention, the upper cover layer and / or the lower cover layer are each formed by a plurality of fiber layers. According to the invention, therefore, the upper cover layer or the lower cover layer or also both the upper and the lower cover layer are each composed of a plurality of fiber layers. As a result, depending on the choice of the number of fiber layers, the property of the leaf spring to be ultimately produced can be influenced. It is also conceivable in the context of the invention, the upper cover layer and the lower cover layer also to be prefabricated as part of an upstream process. Alternatively, however, the individual fiber layers can also be joined together only as part of the connection with the at least one intermediate insert.

In a further development of the aforementioned embodiment, the plurality of fiber layers each have the same lengths. Particularly preferably, the fiber layers of the upper cover layer and / or the lower cover layer extend in the longitudinal direction of the leaf spring from the axial end to the other end of the final leaf spring.

According to the invention, the at least one thickening is formed in each case by a plurality of intermediate inserts. The individual thickening is thus formed by interaction of several depositors, wherein these depositors correspond to one another and are mirrored to each other between the upper cover layer and the lower cover layer. Through this interaction can be realized by the run as a common parts inserts significantly higher thickening.

A leaf spring produced by means of the method according to the invention is characterized in that at least one thickening is formed in the longitudinal direction between ends, wherein at least one insert is provided in the respective region of the at least one thickening between an upper cover layer and a lower cover layer, which as a prefabricated unit with the cover layers is connected. Such a leaf spring is then in particular part of a chassis for a motor vehicle, wherein the leaf spring used can be further made according to the further, previously described variants.

The invention is not limited to the specified combination of the features of the independent or the dependent claims. It also results in ways to combine individual features, even if they emerge from the claims, the following description of preferred embodiments of the invention or directly from the drawings. The reference of the claims to the drawings by use of reference numerals is not intended to limit the scope of the claims.

• 1 eine schematische Darstellung einer erfindungsgemäßen Blattfeder entsprechend einer ersten Ausführungsform der Erfindung, gezeigt im fertiggestellten Zustand;
• 2 eine schematische Darstellung der Blattfeder aus 1, zerlegt in ihre Komponenten;
• 3 eine schematische Einzelansicht eines Einlegers aus 2, gezeigt vor seiner Fertigstellung;
• 4 eine schematische Einzelansicht des Einlegers im fertiggestellten Zustand;
• 5 eine schematische Einzelansicht einer oberen Decklage aus 2, gezeigt vor ihrer Fertigstellung;
• 6 eine schematische Einzeldarstellung einer unteren Decklage aus 2, gezeigt vor ihrer Fertigstellung;
• 7 eine schematische Darstellung einer Blattfeder entsprechend einer zweiten Ausführungsform der Erfindung, gezeigt vor ihrer Fertigstellung; und
• 8 eine schematische Ansicht einer Blattfeder entsprechend einer dritten Ausführungsform der Erfindung, gezeigt vor ihrer Fertigstellung

Advantageous embodiments of the invention, which are explained below, are shown in the drawings. It shows:

• 1 a schematic representation of a leaf spring according to the invention according to a first embodiment of the invention, shown in the finished state;
• 2 a schematic representation of the leaf spring 1 , disassembled into their components;
• 3 a schematic single view of an insert from 2 , shown before its completion;
• 4 a schematic single view of the insert in the finished state;
• 5 a schematic single view of an upper cover layer 2 , shown before its completion;
• 6 a schematic detail of a lower cover layer 2 , shown before its completion;
• 7 a schematic representation of a leaf spring according to a second embodiment of the invention, shown before its completion; and
• 8th a schematic view of a leaf spring according to a third embodiment of the invention, shown before its completion

Out 1 is a schematic view of a leaf spring 1 which is designed according to a first embodiment of the invention. As in 1 can be seen, the leaf spring points 1 two thickenings 2 and 3 on, in the longitudinal direction between ends 4 and 5 spaced from each other. Here is the leaf spring 1 in the area of thickening 2 and 3 compared to end-side sections and an intermediate central region with a significantly greater thickness. 1 shows the leaf spring 1 while in a finished state, in which a plurality of fiber layers, in particular in the form of glass fibers, are surrounded by a plastic matrix and form a fiber-plastic composite. The plastic is formed in particular by a thermosetting plastic and is preferably present as an epoxy resin.

As a special feature is the leaf spring 1 modular-like composed of several, prefabricated components, which made 2 can be seen. So is in 2 to realize that the leaf spring 1 through an upper cover layer 6 , a lower cover layer 7 and a total of four depositors 8th is formed, each having the same structure and between the upper cover layer 6 and the lower cover layer 7 to be ordered. Specifically, the depositors 8th in each case mirrored in pairs to each other at the points between the upper cover layer 6 and the lower cover layer 7 provided where the later leaf spring 1 the thickenings 2 and 3 should have.

The cover layers 6 and 7 and also the depositors 8th are each prefabricated in upstream process steps of several fiber layers, this being for the depositors 8th in the 3 and 4 is shown while 5 the prefabrication of the upper cover layer 6 and 6 the prefabrication of the lower cover layer 7 shows. Regarding the depositors 8th is in 3 to recognize that multiple fiber layers 9 to 13 be arranged one above the other, which have different lengths. This will be the fiber layers 10 to 13 so on the longest fiber layer 9 arranged that the fiber layer 10 with the layered superimposed fiber layers 11 and 12 overlaps and in turn from the uppermost fiber layer 13 is overlapped. This will produce the desired contour of the insert 8th shown, with the fiber layers 9 to 13 then in a furnace process to the in 4 pre-compacted wedge-shaped contour to be ultimately surrounded by a plastic matrix.

How, however, from the 5 and 6 It can be seen, both the upper cover layer 6 , as well as the lower cover layer 7 each of several equal length fiber layers 14 educated. This show the fiber layers 14 each one length, which one at the later leaf spring 1 between the ends 4 and 5 corresponds to the defined length. As well as in the 5 and 6 can be seen, the upper cover layer continues 6 while two fiber layers 14 together, while the lower cover layer 7 through a total of four fiber layers 14 is formed. Both the upper cover layer 6 , as well as the lower cover layer 7 are also precompacted and incorporated in a plastic matrix. In a final process is then off the top liner 6 , the intermediate, four depositors 8th and the lower cover layer 7 the final leaf spring 1 manufactured.

Furthermore, in 7 the components of a leaf spring 15 shown according to a second embodiment of the invention. In contrast to the previous variant are an upper cover layer 16 and a lower cover layer 17 Equal executed by being composed of the same number of fiber layers, in each case four fiber layers. The same is true of the components of a leaf spring 18 out 8th the case in which also the upper cover layer 19 and the lower cover layer 20 have the same structure, so are realized as corresponding components. Unlike the previous variant, the upper cover layer 19 and the lower cover layer 20 but each case formed by two fiber layers.

By means of the method according to the invention, a leaf spring can be produced with a low production cost, wherein at the same time different thickness profiles can be realized without difficulty.

LIST OF REFERENCE NUMBERS

1

leaf spring

2

thickening

3

thickening

4

The End

5

The End

6

upper cover layer

7

lower cover layer

8th

depositors

9

fiber layer

10

fiber layer

11

fiber layer

12

fiber layer

13

fiber layer

14

fiber layer

15

leaf spring

16

upper cover layer

17

lower cover layer

18

leaf spring

19

upper cover layer

20

lower cover layer

Claims (8)

Method for producing a leaf spring (1; 15; 18) from a fiber composite material, wherein the leaf spring (1; 15; 18) consists of a plurality of fiber layers (9 to 14) with at least one thickening (2) extending longitudinally between ends (4, 5) 3), wherein the at least one thickening (2, 3) is defined in each case by at least one insert (8), which is prefabricated as a unit and subsequently in the region of the respectively defined thickening (2, 3) between an upper cover layer (6; 16; 19) and a lower cover layer (7; 17; 20) is arranged, and the at least one thickening (2, 3) is respectively formed by a plurality of intermediate inserts (8), characterized in that corresponding inserts ( 8) are arranged mirrored to each other. Method according to Claim 1 , characterized in that the at least one insert (8) in advance of several fiber layers (10 to 13) is composed, which are connected overlapping each other in at least one section and thereby define a greater thickness in the respective section. Method according to Claim 2 , characterized in that fiber layers (11 to 13) of different lengths are interconnected. Method according to Claim 1 , characterized in that the at least one insert (8) in advance of several fiber layers (9 to 13) is composed, wherein at least one section is made with greater thickness by at least one shorter fiber layer (10 to 13) on at least one longer fiber layer (9) is attached. Method according to Claim 1 , characterized in that the upper cover layer (6; 16; 19) and / or the lower cover layer (7; 17; 20) is formed in each case by a plurality of fiber layers (14). Method according to Claim 5 , characterized in that the plurality of fiber layers (14) of the upper cover layer (6; 16; 19) and the lower cover layer (7; 17; 20) have the same lengths. A leaf spring (1; 15; 18) made of a fiber composite material in which at least one thickening (2, 3) is formed in the longitudinal direction between ends (4, 5), at least one insert (2, 3) in the respective region of the at least one thickening (2, 3). 8) between an upper cover layer (6; 16; 19) and a lower cover layer (7; 17; 20) is provided, wherein the at least one insert (8) as a prefabricated unit with the cover layers (6, 7, 16, 17; 19, 20) is connected, and the at least one thickening (2, 3) in each case by a plurality of intermediate insert (8) is formed, characterized in that corresponding inserts (8) are arranged mirrored to each other. Chassis for a motor vehicle, comprising a leaf spring after Claim 7 ,

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