DE102014222978A1 - Method for producing a bellows spring and bellows spring - Google Patents

Abstract

The invention relates to a method for producing a bellows spring made of fiber-reinforced plastic, comprising the steps of providing a core in the form of a corrugated pipe body in which the flank angle at the outer flanks is less than 75 °, weaving a fiber structure onto the core, removing at least part of the core , Introduction of the braided structure in an outer shape with at least two parts, and solidifying the braided structure In addition, the invention relates to a bellows spring.

Description

The invention relates to a method for producing a bellows spring made of fiber-reinforced plastic.

Due to the increasing safety and comfort needs of customers, motor vehicles are being equipped with more and more components. So that the weight of a motor vehicle does not rise to the same extent, lightweight materials are used to keep the weight approximately constant.

One of these lightweight materials is fiber-reinforced plastic, hereinafter also FVK. The fibers consist of glass fibers or carbon fibers, the respective fiber-reinforced plastics are then also abbreviated to GFRP and CFRP. In fiber-reinforced plastics, the plastic, also called matrix, makes up the largest part of the volume, but the stiffness comes over the fibers. However, fiber volume contents of more than 50% can also be represented.

Out DE 10 2011 083 688 A1 goes out a mold for producing fiber-reinforced plastic components. This comprises four mold parts, two of which cooperate to form a cavity in the plastic part.

DE 10 2011 080 029 A1 relates to a method for producing a spring made of fiber composite material. In this case, a mat made of resin-impregnated fabric is deformed wave-shaped prior to curing of the resin, so that a corrugated semi-finished product is formed, from which a bellows spring can be rolled.

DE 10 2012 202 653 A1 describes a mold for producing a fiber-reinforced plastic component. The molding tool has at least one winding surface for a fiber and is designed such that, together with a second molding tool part, a cavity is created which comprises the winding surface.

DE 10 2011 083 173 A1 discloses a support structure for an axle of a vehicle having at least one connection structure component constructed of an isotropic or quasi-isotropic material. The still existing handlebar and body support is made of fiber-reinforced plastic.

Proceeding from this, it is an object of the present application to provide other motor vehicle components made of fiber-reinforced plastic and methods for their preparation.

To solve this problem, a method according to claim 1 is proposed. Advantageous developments of the invention will become apparent from the dependent claims.

As an essential point of the invention, it is considered that a corrugated pipe body is used as the core for winding up a fiber structure, wherein the flank angle is greater than in the final state and therefore the winding of the braid structure or fiber structure is facilitated on the core. In this case, there is a problem on the flanks to the effect that with decreasing angle the frictional adhesion of the fibers decreases and thereby the risk of slippage of the fiber structure is increased.

The flank angle is the angle between two legs of two mountains of the corrugated bellows spring. The smaller the flank angle, the steeper the transition between mountain and valley.

Preferably, the braiding structure may comprise fibers of matrix material and for strengthening the fibers of matrix material may be heated. In this way, a homogeneous distribution of the matrix material is achieved without much effort. In particular, no additional equipment other than a heater is required.

Alternatively, a resin may be introduced into the outer mold to solidify. This variant is more cost-effective to produce, however, devices for reserving the resin and inserting it into the outer mold are to be provided.

Preferably, a core of elastomer which is filled can be used as the core. A problem in the production of undercut semi-finished products is the removal of the core. Since the core is a corrugated tube body, the core must either remain at least partially in the bellows spring or be removable. The sheath of elastomer is preferred because it is stretchable and deformable and forms a thin release layer between the filler and the material of the bellows spring. In particular, the elastomer shell can remain in the bellows spring, without resulting in a noticeable increase in weight of the finished bellows spring.

Preferably, the shell may be filled with a powdery material, wherein the powdery material is removed after performing the Aufflechtens. As a powdery material, for example, sand can be used. The powdery material must be more or less incompressible in order to maintain the shape of the core as the fibers are being braided.

Advantageously, the shell can be subjected to internal pressure, in particular compressed air, before solidification of the braiding structure. With the help of compressed air can through the powdery Material released volumes are filled so that the above-demanded Aufflechtsteifigkeit the core is given.

Preferably, a core with a flank angle of> 50 ° can be used. Particularly preferably, the flank angle is even> 60 °. At these flank angles, the ratio between the surface change in collapsing the braided structure and the slip resistance during braiding is optimal. The flank angle is preferably <100 °.

After completing the braiding structure and removing the core, the braided structure is introduced into an outer mold. The parts of the outer shape preferably include the braiding structure such that the flank angle is reduced to less than 10 °. In particular, the flank angle can be reduced to 0 ° or almost 0 °. This gives the bellows spring or the braided structure, from which the finished bellows spring is to be obtained, their final form with introduction into the outer tool.

In addition, the invention relates to a bellows spring for a motor vehicle. This is characterized in that it is manufactured by a method as described.

Furthermore, the invention relates to a motor vehicle with at least one bellows spring as described.

Further advantages, features and details emerge from the figures and exemplary embodiments described below. Showing:

1 a core in perspective,

2 a core in longitudinal section,

3 an outside tool,

4 a bellows spring in perspective,

5 a bellows spring in longitudinal section, and

6 a Ablauschema a method for producing a bellows spring.

1 shows a core 1 in the form of a corrugated tube body, in a perspective view. The core consists of a shell 2 made of elastomer. In the shell 2 there is sand 3 as a powdery filler. The core is formed as described as corrugated pipe body. That is, mountains 4 and valleys 5 alternate several times in succession. Further details of the core 1 go out 2 out.

2 shows the core 1 according to 1 in longitudinal section. In this illustration, the flank angle 6 shown the angle between two legs 7 two mountains 4 is. The parallel 8th is the tangent through the highest point of a mountain 4 , The larger the flank angle 6 is, the flatter is the slope to the mountains 4 The more easily a braided structure can be applied to the core 1 be raised or braided. The flank angle is therefore preferably> 50 °, in particular> 60 °, but preferably <100 °. When choosing this flank angle 6 for the core 1 a good braiding result is achieved, and upsetting to the final desired flank angle of <10 ° is nevertheless possible.

3 shows an outside tool 10 , consisting of three parts 12 . 14 and 16 , The three parts 12 . 14 and 16 have recesses 18 on top of that on the core 1 woven braided structure is pushed together, so that the flank angle 6 is reduced.

Accordingly, in the outer tool 10 solidified bellows spring 20 a form on, as in 4 shown.

The cross section of the bellows spring 20 is in 5 shown. It can be seen that the flank angle 6 0 ° or nearly 0 °, the shell 22 the bellows spring 20 consists of the fibers of fiber material and matrix material. These may be melted fibers of matrix material or else a resin that is in the outer tool 10 was introduced.

6 shows a method for producing a bellows spring made of fiber-reinforced plastic. This involves several steps: In the first step S1, an envelope of elastomeric material is provided. The flank angle 6 on the outer edges is greater than 30 °. In step S2, the core becomes 1 filled with a powdery material. Sand is preferably used, since it only melts at high temperatures and is fine-grained. This will change the shape of the core 1 stabilized. With the steps S1 and S2, a possibility is created, a core 1 to provide in the form of a corrugated pipe body.

In the next step S3, a fiber structure is applied to the core 1 been platted. This is due to the comparatively small flank angle 6 easily realizable. After the braiding, in step S4, the filling of the core is removed 1 , so the powdery material. As a result, the braided structure becomes deformable. This is at least a part of the filling and thus the core 1 taken.

Thereafter, in step S5, the braided structure becomes an outer tool 10 with at least two parts 12 . 14 and 16 introduced, the flank angle 6 is reduced. In particular, the flank angle is thereby 6 reduced to the final angle. Subsequently, in step S6, the braided structure is solidified.

LIST OF REFERENCE NUMBERS

1

 core

2

 shell

3

 sand

4

 mountain

5

 valley

6

 flank angle

7

 leg

8th

 parallel

9

 longitudinal axis

10

outer tool

12

part

14

part

16

part

18

recess

20

Rotor

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 102011083688 A1 [0004]
• DE 102011080029 A1 [0005]
• DE 102012202653 A1 [0006]
• DE 102011083173 A1 [0007]

Claims (12)

Method for producing a bellows spring ( 20 ) made of fiber-reinforced plastic, comprising the steps of: - providing a core ( 1 ) in the form of a corrugated pipe body, in which the flank angle ( 6 ) is greater than 30 ° on the outer flanks, - weaving a fibrous structure onto the core ( 1 ), - removing at least part of the core ( 1 ), - introducing the braided structure into an external tool ( 10 ) with at least two parts ( 12 . 14 . 16 ), and - solidifying the braided structure. A method according to claim 1, characterized in that the braided structure contains fibers of matrix material and to solidify the fibers and matrix material are heated. A method according to claim 1, characterized in that for solidifying a resin material in the outer tool ( 10 ) is introduced. Method according to one of the preceding claims, characterized in that as core ( 1 ) a case ( 2 ) is used made of elastomer, which is filled. Method according to claim 4, characterized in that the envelope ( 2 ) with a powdery material ( 3 ), the powdery material ( 3 ) after weaving the fiber structure onto the core ( 1 ) Will get removed. Method according to one of claims 4 or 5, characterized in that the envelope ( 2 ) is subjected to internal pressure, in particular compressed air, prior to solidification of the braiding structure. Method according to one of the preceding claims, characterized in that a core ( 1 ) is used with a flank angle greater than 50 °. Method according to one of the preceding claims, characterized in that a core ( 1 ) is used with a flank angle greater than 60 °. Method according to one of the preceding claims, characterized in that the parts ( 12 . 14 . 16 ) of the external tool ( 10 ) include the braiding structure such that the flank angle ( 6 ) is reduced to less than 20 °. Method according to one of the preceding claims, characterized in that the parts ( 12 . 14 . 16 ) of the external tool ( 10 ) include the braiding structure such that the flank angle ( 6 ) is reduced to less than 10 °. Bellows spring for a motor vehicle, characterized in that the bellows spring ( 20 ) is produced by a method according to one of the preceding claims. Motor vehicle, characterized in that it comprises a bellows spring according to claim 11.

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