DE102015103314B4 - Method of manufacturing a bending beam - Google Patents

Abstract

A method for producing a bending beam (1) from fiber composite material, characterized by the following process steps: - Providing an elongated semi-finished fiber product (7) with - over the length (L) constant thickness (D) or in length sections of different thicknesses (D), wherein - Over the entire length (L) the thickness (D) is less than or equal to the width (B), - lateral compression of the end areas in the direction of the width (B), so that the width (B) decreases in the end areas and leads to an increase in the Thickness (D) in the end areas leads and - Simultaneous or subsequent pressing of the top (5) and bottom (6) of the bending beam (1) to be produced in the direction of the thickness, so that the bending beam (1) produced with it has an increasing thickness (D) in relation to the area having its free end out.

Description

The present invention relates to a method for producing a bending beam from fiber composite material according to the features in claim 1.

It is known from the prior art to use bending beams as leaf springs, particularly in automotive engineering. These are used in particular as longitudinal or transverse leaf springs.

A manufacturing method for such a leaf spring made of fiber composite material is, for example, from EP 2 492 074 B1 known. First, a semi-finished product made of at least two superimposed textile layers is provided, placed in a preform and matrix resin is injected via an RTM process.

Alternatively, it is also possible to first stack several layers of a semifinished product on top of one another and then press them together, the layers already being pre-impregnated with resin and / or a resin being applied to the layers during the stacking.

Particularly when it is installed in a motor vehicle, the leaf spring produced in this way is connected to an axle or the body. For this purpose, it is known from the prior art, for example, to provide openings in the leaf spring which are penetrated by a bolt, in particular a heart bolt. In operation of the motor vehicle, however, stress cracks can form due to the alternating bending stress on the leaf spring, which can lead to premature failure of the leaf spring.

From the DE 10 2013 007 230 A1 it is known that thickenings can be formed at the bearing points, which are usually located at the ends of a spring. However, the thickness decreases again after a bearing eye in the longitudinal direction towards the free end.

The object of the present invention is therefore to provide a manufacturing method with which a leaf spring can be manufactured in a process-optimized manner and, above all, inexpensively with connection areas.

The object is achieved according to the invention with a method for producing a bending beam from fiber composite material having the features in claim 1.

Advantageous variant embodiments of the present invention are the subject of the dependent claims.

• - Bereitstellen eines länglichen Faserhalbzeuges mit
• - über die Länge konstanter Dicke oder in Längenabschnitten voneinander verschiedener Dicke, wobei
• - über die gesamte Länge die Dicke kleiner gleich der Breite ist,
• - seitliches Verpressen der Endbereiche in Richtung der Breite, so dass in den Endbereichen die Breite abnimmt und zu einer Zunahme der Dicke in den Endbereichen führt und
• - Gleichzeitiges oder nachgeschaltetes Verpressen von Oberseite und Unterseite des herzustellenden Biegebalkens in Dickenrichtung, so dass der damit hergestellte Biegebalken eine zunehmende Dicke zum Bereich seines freien Endes hin aufweist.

The method according to the invention for producing a bending beam made of fiber composite material is characterized by the following method steps:

• - Providing an elongated semi-finished fiber product with
• - Over the length of constant thickness or in length sections of different thicknesses, wherein
• - the thickness is less than or equal to the width over the entire length,
• - Lateral compression of the end areas in the direction of the width, so that the width decreases in the end areas and leads to an increase in the thickness in the end areas and
• Simultaneous or subsequent pressing of the top and bottom of the bending beam to be produced in the direction of the thickness, so that the bending beam produced therewith has an increasing thickness towards the region of its free end.

First, a semi-finished fiber product is provided. In the context of the invention, the semifinished fiber product is either an already pre-impregnated semifinished fiber product, that is to say fibers that have already been mixed with a matrix resin, or, alternatively, only the pure fiber material. The fiber materials used here are in particular aramid fibers, carbon fibers, glass fibers, metal fibers or other known fiber types. In the case of two-dimensional semifinished fiber products, a fleece or else a scrim or woven fabric is used in particular. For this purpose, at least two layers are particularly preferably stacked on top of one another. Prepregs can also be used for this purpose within the scope of the invention.

However, it is also conceivable that the semifinished fiber product is wound. Either a core material can be wrapped around or patches and / or prepreg layers can also be wrapped around. In particular, these materials are wrapped with tow pregs. It is also conceivable to use a wet winding method within the scope of the invention.

The semi-finished fiber product provided in this way preferably has a constant thickness over its entire length. In the context of the invention, however, it is also conceivable that the respective length sections have a thickness that differs from one another. In particular, for the production of a leaf spring, provision is made for the thickness to be less than or equal to the width over the entire length. In particular, however, the thickness is smaller than the width. The semifinished fiber product particularly preferably has a width that is constant over its entire length.

According to the invention, it is now provided that the end regions are pressed laterally. The pressing takes place in the direction of the width, so that the width decreases in the end regions and leads to an increase in the thickness in the end regions. The deformation produced in this way can in particular be used to make a form-fitting connection in the end regions, for example to connect the leaf spring to a body of a motor vehicle. A bending beam is very particularly preferably produced as a longitudinal leaf spring.

Provision is now made for the top and bottom of the bending beam to be produced to be pressed in the thickness direction either at the same time as the pressing of the end regions in the width direction. The pressing in the thickness direction can, however, also follow the pressing in the width direction.

In the case of an already pre-impregnated semi-finished fiber product, this can at least partially cure in the thickness direction after the pressing of the top and bottom has been completed, so that no change in shape takes place after the press tool has been released. If, on the other hand, it is a semifinished fiber product without matrix components, the press tool can be designed as a cavity in such a way that a resin is injected into the press-forming tool. In particular, this takes place as an RTM process.

Furthermore, particularly preferably, a tapering in the thickness direction can be produced in the length section with reduced thickness by pressing in the thickness direction. This is particularly conceivable for producing a central connection to the leaf spring produced. In particular, a motor vehicle axle can then be mounted positively with a receptacle in the area of the central connection.

It is also conceivable that not only the end regions, but also a length section are pressed in the lateral direction of the width. Here, too, the lateral pressing causes a reduction in the width, which is accompanied by an increase in the thickness. Due to the reduced width, it is possible to establish a corresponding central connection here via a form-fitting coupling.

The end regions are particularly preferably pressed in the width direction in such a way that the width decreases towards the free end, in particular it decreases linearly or progressively or degressively. The associated increase in thickness is designed accordingly in such a way that the thickness increases towards the free end. The increase in thickness is also linear or progressive or degressive.

Furthermore, particularly preferably, a length section present on the semifinished fiber product, which has a greater thickness, can be flattened in the direction of the thickness during pressing in such a way that the width increases in this length section.

The entire bending beam is particularly preferably produced with a curvature extending over its length.

The bending beam is particularly preferably produced in such a way that the lateral pressing in the width direction and the pressing in the thickness direction result in a final shaping and after the pressing process the component made from fiber composite material is completely made and further shaping processing steps, for example cutting to size or edge trimming, are no longer necessary are.

• 1a) und b) einen erfindungsgemäß hergestellten Biegebalken in Seitenansicht und Draufsicht und
• 2a) bis c) ein erfindungsgemäßes Herstellungsverfahren.

Further advantages, features, properties and aspects of the present invention are part of the description below. Preferred design variants are shown in the schematic figures. These serve for a simple understanding of the invention. Show it:

• 1a) and b) a bending beam produced according to the invention in side view and top view and
• 2a) to c ) a manufacturing method according to the invention.

In the figures, the same reference symbols are used for identical or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows a bending beam produced according to the invention 1 in case of 1a) in a side view and in the case of 1b) in a top view. It can be clearly seen that the bending beam 1 in the side view according to 1a) along its entire length L. has a curvature. The ends 2 of the bending beam 1 take it in thickness D. with a progressive course 3rd to. The increase in thickness D. in the area of the free ends 2 is caused by a decrease in width B. , easy to recognize in 1b) . Here is in the area of the free ends 2 each the width B. has been reduced by a lateral compression in the direction of the width B. . The ends 2 are each to the free end 2 towards with a linear course 4th been compressed so that these taper and lead to an increase in thickness D. to lead. The fat D. is shown here only on the top 5 of the manufactured bending beam 1 enlarged. However, it is also conceivable the thickness D. both at the top 5 as well as at the bottom 6th to enlarge. This depends on the pressing process in the direction of the thickness.

2a) to c ) show a manufacturing method for a bending beam according to the invention 1 . According to 2a) becomes a semi-finished fiber product 7th provided which over its length L / 2 a constant width B. having. L / 2 corresponds to half the length due to only one side shown L. out 1 . The semi-finished fiber product made available in this way 7th can for example be formed from several fiber layers stacked one on top of the other. This is in a next step in the process in the area of its free end 2 from one side each 8th with a press force F. in the direction of width B. applied so that the semi-finished fiber 7th in the area of its end 2 in width B. is rejuvenated. The compression causes an increase in thickness D. , clearly visible in 2c ). The bending beam made with it 1 shows an increasing thickness here D2 to the area of its free end 2 out on.

List of reference symbols

1 -

Bending beam

2 -

end

3 -

progressive course

4 -

linear course

5 -

Top to 1

6 -

Bottom of 1

7 -

Semi-finished fiber products

8th -

Page to 7

B -

width

D -

thickness

L -

length

L / 2 -

length

D2 -

thickness

F -

Pressing force

Claims (11)

Process for the production of a bending beam (1) from fiber composite material, characterized by the following process steps: - Providing an elongated semi-finished fiber product (7) with - Over the length (L) of constant thickness (D) or in length sections of different thicknesses (D), wherein - over the entire length (L) the thickness (D) is less than or equal to the width (B), - Lateral compression of the end areas in the direction of the width (B), so that the width (B) decreases in the end areas and leads to an increase in the thickness (D) in the end areas and - Simultaneous or subsequent pressing of the top (5) and bottom (6) of the bending beam (1) to be produced in the direction of the thickness, so that the bending beam (1) produced therewith has an increasing thickness (D) towards the area of its free end. Procedure according to Claim 1 , characterized in that the semi-finished fiber product (7) is a stack having at least two layers, preferably made of prepregs. Method according to one of the Claims 1 or 2 , characterized in that the semi-finished fiber product (7) is a wrapped core material, in particular patches wrapped with tow pregs and / or prepreg layers or is produced by wet winding. Method according to one of the Claims 1 to 3rd , characterized in that the pressing is carried out in the thickness direction in a compression molding tool and in particular a resin is injected into the compression molding tool. Method according to one of the Claims 1 to 4th , characterized in that a longitudinal leaf spring is produced. Method according to one of the Claims 1 to 5 , characterized in that a tapering is produced in a length section with reduced thickness (D) by pressing in the direction of the thickness, in order to produce a central connection. Method according to one of the Claims 1 to 6th , characterized in that the semifinished fiber product (7) has a width (B) that is constant over the length (L). Method according to one of the Claims 1 to 7th , characterized in that a middle length section is pressed laterally in the direction of the width (B). Method according to one of the Claims 1 to 8th , characterized in that the bending beam (1) is produced with a curvature extending over its length (2). Method according to one of the Claims 1 to 9 , characterized in that a matrix resin of the semifinished fiber product (7) only hardens completely in the direction of the thickness after the pressing has been completed. Method according to one of the Claims 1 to 10 , characterized in that the semifinished fiber product (7) has a greater thickness (D) in a length section, the width (B) increasing in this length section during compression in the thickness direction.

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