WO2008055458A1

WO2008055458A1 - Method for producing leaf springs from a fiber composite material

Info

Publication number: WO2008055458A1
Application number: PCT/DE2007/001841
Authority: WO
Inventors: Rainer Förster; Matthias Voigt
Original assignee: Ifc Composite Gmbh
Priority date: 2006-11-06
Filing date: 2007-10-16
Publication date: 2008-05-15
Also published as: DE102006052137B4; DE102006052137A1

Abstract

The invention relates to a method for producing leaf springs (28) from a fiber composite material, comprising the following steps: covering the upper side and the lower side of a fiber strand (2), consisting of fibers that are aligned at least in parallel, with at least one cover material web (3, 4), wetting the fibers of the fiber strand (2) with a not yet hardened plastic matrix (14), heating the covered and plastic matrix-coated fiber strand (2) to impregnate the fibers of the fiber strand (2) with the not yet hardened plastic matrix (14), cooling the covered plastic matrix-impregnated fiber strand (2), cutting the covered plastic matrix-impregnated fiber strand (2) to individual prepregs (11') or winding it up to a prepreg coil (20), placing a plurality of layers of prepregs (11) vertically one on top of the other on a convex surface (22) to give an unfinished leaf spring (23), cooling the unfinished leaf spring (23) on a convex surface (22), pressing the unfinished leaf spring (23) in a press (25) to give a pressed unfinished leaf spring (23'), heating the pressed unfinished leaf spring (23') and completing the unfinished leaf spring (23') to give the finished leaf spring (28), predetermined temperatures (T) being adjusted on the respective material or on the respective intermediate product in all steps of manufacture and maintaining the respective temperatures (T) for predetermined intervals (Δt).

Description

Process for producing leaf springs from a fiber composite material

The invention relates to a method for the production of leaf springs made of a fiber composite material.

For example, from EP 0 084 101 A2 it is known that leaf springs can be produced from a fiber composite material. Such leaf springs have over conventional leaf springs made of metallic materials the advantage of lower weight and a longer shelf life. By choosing the laminate layers and the orientation of the fibers in a plastic matrix, the spring characteristic can be influenced within wide limits.

In general, leaf springs made of fiber-reinforced materials of so-called wet laminates or prepregs are produced, which are layered with the desired fiber orientation and then pressed and cured.

The term prepreg is known to mean a semifinished product or a precursor for the production of articles from a fiber composite material. A prepreg consists of continuous fibers and an uncured thermoset or thermoplastic plastic matrix. In this case, the continuous fibers may be unidirectionally aligned or present as tissue or scrim. The plastic matrix is usually a mixture of a synthetic resin, a hardener and an accelerator. Furthermore, special additives can be added to produce further desired properties of the prepreg. For example, resins based on epoxy resin or vinyl ester resin are used as synthetic resins.

To produce prepregs, the fibers are deposited in a desired manner on a support and then wetted with the plastic matrix. By cooling, until freezing, the prepreg becomes chemically reactive Hardener and the accelerator with the resin prevented until the prepreg is to be used for the production of a final product. For example, several prepreg layers are stacked and cut to produce a fiber composite leaf spring. By subsequently heating this workpiece beyond the reaction temperature of the hardener, the curing process begins, eventually leading to the desired end product. If this heating is carried out in a press and in an autoclave at atmospheric negative pressure, air bubble-free end products can be produced with a very high fiber content and comparatively low plastic matrix content.

In order to be able to produce prepregs in a continuous production process, it is necessary to supply a strand of said endless fibers to a production apparatus of this type. It is important to ensure that the fibers remain in the desired spatial orientation. The fiber distribution should therefore usually be homogeneous. In addition, should occur in the supply and further processing of the fiber strand as small as possible fiber breakage.

In addition, the fiber strand with the said plastic matrix, ie the mixture of at least resin and hardener must be wetted. It is important that the distribution of the plastic matrix takes place uniformly or all fibers of the fiber strand are impregnated by the plastic matrix. In addition, not too much plastic matrix may reach the fiber strand, since this would result in a lateral discharge of the excess liquid to an undesirably large extent.

If the prepreg strand produced is to be cut into desired longitudinal pieces or rolled up as a roll and then stored temporarily, the fiber strand during production of the prepreg strand is preferably to be covered on its underside and on its upper side with a covering material web. When placing these Abdeckmaterialbahnen on the fiber strand it can In addition, the fibers of the upper and / or the lower fiber layer of the fiber strand are folded in an unintentional manner transversely to the longitudinal extent of the fiber strand. In a fiber composite end product so folded fibers contribute little to the desired material properties, which is why such fiber folding should be avoided.

The invention is therefore based on the object to present a method for producing leaf springs made of a fiber composite material, with which the technical problems described above can be mastered and a high-quality leaf spring can be produced. Thus, in particular, it is to be achieved that the fibers are present in the leaf spring of a desired orientation, that the not yet hardened plastic matrix in the leaf spring reaches all fibers in sufficient quantity, that the extent of fiber breakage in the leaf spring is minimized, and that a folding of the Fibers transverse to the longitudinal extent of the fiber strand is at least largely avoided.

The solution to this problem arises from the features of the main claim. Advantageous developments and refinements of the invention can be taken from the associated subclaims.

After a lengthy investigation on test facilities, the invention was based on the finding that a leaf spring made of a fiber composite material can meet the very high quality requirements prevailing in the automotive industry, if in all process steps for producing the leaf spring, from the provision of materials in a factory up to Quality control, the temperatures of the individual materials and intermediates and the periods in which they are exposed to the respective temperature, are closely matched and constantly monitored.

To clarify the invention, the description is accompanied by a drawing. In this shows 1 is a highly schematic production flowchart for producing a fiber composite leaf spring according to a first variant,

2 shows a production flowchart as in FIG. 1 according to a second variant,

Fig. 3 is a schematic side view of an apparatus and a production process, with which a prepreg strand can be manufactured continuously for producing the leaf spring, and

Fig. 4 is a schematic side view of other manufacturing devices and the further production process with which individual leaf springs are made from the prepreg strand.

FIGS. 3 and 4 accordingly show a schematic illustration of a production plant for producing leaf springs from a fiber composite material. The temperatures to which the materials or intermediate products are exposed during their production or which reach them, as well as the periods over which these materials or intermediates are exposed to these temperatures are for two in the range of a heating table 6 slightly different production facilities in FIG. 1 and FIG. 2 together with the associated method steps.

Independently of the process parameters which are slightly different in the region of the heating table 6, the procedure is followed in each case by the same basic process steps according to the invention. These are according to the features of the main claim:

- Covering the top and the bottom of a fiber strand 2, which consists of at least parallel aligned fibers, with at least one Abdeckmaterialbahn 3, 4th

Wetting the fibers of the fiber strand 2 with a not yet hardened plastic matrix 14, Heating the covered plastic matrix-coated fiber strand 2 for impregnating the fibers of the fiber strand 2 with the not yet set plastic matrix 14,

Cooling the covered plastic matrix impregnated fiber strand 2,

Cutting off the covered plastic matrix-impregnated fiber strand 2 into individual prepregs 11 ',

Depositing a plurality of layers of prepregs 11 'vertically one above the other on a convexly curved surface 22 to a raw leaf spring 23,

Cooling the green leaf spring 23 on a convexly curved surface 22,

Pressing the green leaf spring 23 in a press 25 into a pressed raw leaf spring 23 ',

Heating the pressed green leaf spring 23 ', and

- Finishing the pressed raw leaf spring 23 'to the finished leaf spring 28, wherein in all manufacturing steps predetermined temperatures T are set to the respective material or to the respective intermediate product, and in which the respective temperatures T over predetermined periods .DELTA.t be maintained.

As a synopsis of Figures 1 and 3 to 4 and Figures 2 to 4 of the two embodiments, the materials are resin, hardener and accelerator to form the initially still liquid plastic matrix 14 as well as the glass fibers of a fiber strand 2 of the production plant 1 in the goods receipt WE stored in a factory with a temperature T1 of 23 ° C ± 10 ⁰ C.

In order to produce the still liquid plastic matrix 14, Δt1 of 22 hours to 26 hours, preferably 24 hours (FIG. 1, FIG. 2), in each of the three parallel process steps A, B and C, in each case separate the synthetic resin in one Process step A to a temperature of T2 = 8O ⁰ C ± 10 ⁰ C, the curing agent in a process step B to a temperature of T3 = 55 ⁰ C ± 10 ° C and the accelerator in a process step C to a temperature of T4 = 35 ° C ± 1O ⁰ C and then according to predetermined mixing proportions mixed together. This sets a certain mixture temperature.

After the formation of the still liquid plastic matrix 14, the sides of two cover material webs 3 and 4, which face later on to the fiber strand 2, but at least the lower cover material web 3 are then coated with the plastic matrix 14, which is conveyed by feed devices 12,

13 to the Abdeckmaterialbahnen 3, 4 are passed (step D, F, Fig. 3). The Abdeckmaterialbahnen 3, 4 and the fibers of the fiber strand 2, before coating with the plastic matrix 14, the above-mentioned initial temperature T1 = 23 ° C ± 10 ⁰ C. The coating with the plastic matrix 14 takes place in such a way that that side of the at least one Abdeckmaterialbahn 3, 4 is occupied, which later comes into contact with the fiber strand 2.

The lower cover material web 4 is preferably made of a plastic film and the upper Abdeckmaterialbahn 3 preferably from a coated paper material.

Subsequently, the two Abdeckmaterialbahnen 3, 4 are transported to the heating table 6. In this case, the upper Abdeckmaterialbahn 3 is guided around a Ablegrolle 5, which rotates the hitherto upwardly facing underside of Abdeckmaterialbahn 3 down and this Abdeckmaterialbahn 3 so deposits on the fiber strand 2 that the plastic matrix 14 comes to rest on the upper side of the fiber strand 2 , The Ablegkraft F1 of the Ablegrolle 5 is comparatively small, so that it is ensured that no or only a relatively small proportion of fiber fraction is formed by the contact pressure. The lower Abdeckmaterialbahn 4 is pulled over an input-side portion 16 of the heating table 6 and optionally preheated there.

In the merging of the two Abdeckmaterialbahnen 3, 4 with the fiber strand 2 is in a process step F with the plastic matrix

14 coated at least one Abdeckmaterialbahn 3 and / or 4 and the fiber sträng 2 pulled over the surface of the heating table 6. The merging of the fiber strand 2 and the two Abdeckmaterialbahnen 3, 4 takes place on a convex curved surface 15 of the heating table 6 in the region of a first heating zone S1 of three heating zones S1, S2 and S3 thereof. These heating zones are equipped with an electric heater or hot water heater, not shown, which allow a relatively accurate adjustment of the temperature of the hotplate surface 15 in the respective heating zones S1, S2 and S3. The heat treatment of the covered and plastic matrix-occupied fiber strand 2 takes place in the three heating zones S1 to S3 in the process steps G, H and I.

In a first embodiment variant of the heating table 6, the fiber strand 2 covered by the coated covering material webs 3, 4 along the first heating zone S1 of the heating table 6 to a temperature of T5 = 75 ⁰ C ± 1O ⁰ C along the second heating zone S2 of the heating table 6 a temperature of T6 = 110 ° C ± 1O ⁰ C and brought along the third heating zone S3 of the heating table 6 to a temperature of T7 = 120 ⁰ C ± 10 ° C. The respective Heiztischzonen S1 to S3 have a related surface temperature, the last heating zone S3 has the highest temperature.

In a slightly different shaped heating table 6 covered with the Abdeckmaterialbahnen 3, 4 fiber strand 2 along the first heating zone S1 of the heating table 6 to a temperature of T5 = 100 ° C ± 10 ⁰ C, along the second heating zone S2 of the heating table 6 to a Temperature of T6 = 15O ⁰ C ± 1O ⁰ C and heated along the third heating zone S3 of the heating table 6 to a temperature of T7 = 8O ⁰ C ± 10 ⁰ C. The respective Heiztischzonen S1 to S3 have a related surface temperature on the middle heating zone S2 has the highest temperature.

The transport of the plastic matrix 14 from the upper and lower Abdeckmaterialbahn 3, 4 in the depth of the fiber strand 2 towards each individual fiber is substantially behind the Ablegrolle 5, when the composite structure fiber strand 2, Abdeckmaterialbahnen 3, 4 and plastic matrix 14 is pulled with a tensile force acting on this F6 on the convexly curved heating table 6 with its three different heating zones S1, S2 and S3. Since this fiber strand 2 covered with the covering material webs 3, 4 is pulled over the convexly curved heating surface 15 and follows this convex geometry with respect to its direction of movement, the tensile force F6 results in a normal force F2 which the two covering material webs 3, 4 with their plastic matrix 14 and the fibers of the fiber strand 2 presses against the heating table 6. In this case, the heated plastic matrix 14 penetrates the fiber strand 2, so that all its fibers are gently and comparatively slowly impregnated. A sufficiently large table length combined with a transport speed V adapted in this respect, for example from 0.05 m / s to 0.2 m / s, ensure that the fiber strand 2 is completely penetrated by the plastic matrix 14 despite the comparatively low normal force F2.

Due to the fact that wetting of the fibers of the fiber strand 2 with the plastic matrix 14 does not use any pressure or calender rolls with comparatively high contact pressures, the fiber breakage to be recorded is advantageously small. Since all the fibers of the fiber strand 2 and the upper Abdeckmaterialbahn 3 and the lower Abdeckmaterialbahn 4 are pulled at the same transport speed V on the heating table 6, resulting no or only negligible relative speeds of these elements against each other, so that the initially explained fiber folding does not occur or only slightly ,

In order to minimize the residence time on the heating table 6 or to build the heating table comparatively short, this is provided with the already mentioned three heating zones S1, S2 and S3. These heating zones S1, S2 and S3 enable a systematic temperature control, in particular of the plastic matrix 14, wherein initially a targeted increase in temperature and thus an increase in viscosity is carried out, which facilitates the wetting of the fibers of the fiber strand 2 with the plastic matrix 14. As seen in the transport direction behind the Ablegrolle 5 three smoothing rollers 7, 8 and 9 are arranged on the manufacturing apparatus 1 according to FIG. 3, which press with a comparatively low contact force or smoothing force F3, F4, F5 on the upper side of the upper Abdeckmaterialbahn 3 and thereby a Smoothing the same. Such a smoothing of the upper side of the upper Abdeckmaterialbahn 3 may be useful, since the Ablegkraft F1 of the Ablegrolle 5 is relatively low. These smoothing rollers 7, 8 and 9 are preferably arranged in the region of the third heating zone S3 of the heating table 6.

When leaving the heating table 6, the average temperature of the covered and plastic matrix impregnated fiber strand 2 in this embodiment is about 60 ⁰ C. To lower this temperature further and in particular to prevent or stop the chemical reaction of the hardener with the resin of the still liquid plastic matrix 14 , this fiber strand 2 is pulled over the cooled surface of a cooling table 10 in a method step J. The impregnated with the plastic matrix 14 fiber strand 2 has on leaving the cooling table 10 to a temperature of T8 = 18 ° C ± 4 ° C according to the first variant or = comprising 18 ° C ± 4 ⁰ C according to the second variant T8. This second variant is the one in which the third heating zone S3 of the heating table 6 is cooler than the middle heating zone S2.

Subsequently, according to a method step K, the prepreg strand 11 is cut into pieces 11 'of defined length or wound into a prepreg roll 20. The Abdeckmaterialbahnen 3, 4 later allow easy unwinding of the prepreg roll 20 or a separation of stacked prepregs 11 '. The cutting of the prepreg strand 11 into individual prepreg pieces 11 ', or the winding of the prepreg strand 11 to a prepreg roll 20 ± 10 ° C is carried out at an ambient temperature of T9 = 23 ⁰ C.

The entire period between the feeding or merging of Abdeckmaterialbahnen 3, 4 and the fiber strand 2 on the heating table 6 and the local heat treatment and the cooling phase on the Cooling table 10 is referred to as period Δt2 (FIG. 1, FIG. 2). Whose duration is not specified here, since this is dependent on the length of the heating table 6 and the length of the cooling table 10 and the transport speed V, with which the Faserstrahg is drawn over these two tables.

The next process step L is characterized in that the prepreg pieces 11 'or the prepreg roll 20 at a temperature of T10 = 8 ° C + 4 ° C / -2 ° C for a period of Δt3 = 12 hours in an air-conditioned Room 29 are stored. During this period, the prepregs mature to ensure complete impregnation of all fibers and expel air bubbles from the composite body.

In the next step M, the prepreg roll 20 is cut into prepreg pieces 11 'and these, or previously cut prepreg pieces 11', at a temperature of T11 = 21 ⁰ C ± 3 ° C within a period of Δt4 = 30 minutes to raw leaf springs 23 stacked vertically one above the other and then stored temporarily. In the process, these prepregs 11 'are stacked on a concavely curved surface 22 of a construction form 21 which largely corresponds to that geometry which also has a press mold 26 of a press 25 which is used later.

In a subsequent process step N, the raw leaf springs 23 are stored in a conditioned air-free space 24 substantially free of condensate at a temperature of T12 = 21 ° C + 3 ° C for a period of Δt5 = 24 hours, so that also in This process step, a further maturation process can be done. In this intermediate storage, the emergence of excess synthetic resin matrix 14 from this composite body is favored because of the curved placement of the stacked prepregs as the green leaf spring 23.

In a subsequent process step O, the raw leaf springs 23 are pressed in the press 25 at a temperature of T13 = 125 ° C to 180 ⁰ C over a period Δt6 = 35 minutes to 42 minutes with a pressing force. there the entire superfluous plastic matrix 14 is pushed out of the composite body and the shape of the later leaf spring 28 is largely produced. In addition, a first setting of the plastic matrix 14 remaining in the green leaf spring 23 'takes place in the press 25.

Following this, in a method step P, the pressed green leaf spring 23 "is removed from the press 25 and deposited in a tempering furnace 27. Here, the crude leaf springs 23 'remain at a temperature of T14 = 16O ⁰ C for a period of Δt7 = 4 hours, whereby the binding process in the leaf springs is completed.

Preferably, in this method it is provided that the raw leaf springs 23 'are mounted in the said conditioned space 24 and / or in the aforementioned tempering furnace 27, respectively, on a convexly curved base 22 whose surface geometry is largely consistent with the shape of a press 25.

Finally, the method that the respective raw leaf springs 23 'cooled after the heat treatment in the annealing furnace 27 to a temperature of T15 = 23 ° C ± 1O ⁰ C, and in a step Q1 within a period of Δt8 = 5 provides according to the invention, minutes be subjected to a finishing, such as for degree elimination, be subjected to a test bench test in a step Q2 during a period Δ9 = 2 minutes and finally in a step Q3 in a period .DELTA.t10 = 3 minutes of goods issue control.

reference numeral

Manufacturing device fiber strand; Fiber Upper cover material Lower cover material Beading roller Heating table Straightening roller Straightening roller Straightening roller Cooling table Prepreg strand 'Cut off prepreg Liquid plastic matrix supply device Liquid plastic matrix supply device Liquid plastic matrix Hot stage surface Input side of heating table Prepreg roller Structure for building the green leaf spring from prepreg layers Convex curved surface the type of construction Raw leaf spring made from prepreg layers' Pressed raw leaf spring Air-conditioned room Press mold Tempering furnace Finished leaf spring Air-conditioned room A preheating of the synthetic resin

B Preheating of the hardener

C preheating the accelerator

D coating the lower Abdeckmaterialbahn with the plastic matrix

E Coating of the upper covering material web with the plastic matrix

F Merging of fiber strand and Abdeckmaterialbahnen

F1 Auflegkraft the Auflegrolle 5

F2 Normal force component of tensile force F6 on the strand

F3 contact force of the smoothing roller 7

F4 contact force of the smoothing roller 8

F5 contact force of the smoothing roller 9

F6 traction

G heating of the covered fiber strand on a first heating zone

H heating of the covered fiber strand on a second heating zone

I heating the covered fiber strand on a third heating zone and smoothing

J cooling the covered fiber strand on a cooling table

K winding up the covered fiber strand

L Unrolling of the prepreg strand 11

M Laying prepregs on a convexly curved base

Interim storage of stacked prepregs in a cold room

O pressing the stacked prepregs

P heating the raw leaf spring

Q1 finishing

Q2 test bench

Q3 Outgoing goods inspection

S1 Input side heating zone of the heating table 52 Middle heating zone of the heating table

53 Output side heating zone of the heating table

T1 Temperature of the materials at the beginning of production

T2 preheating temperature of the synthetic resin

T3 preheating temperature of the hardener

T4 preheat temperature of the accelerator

T5 Surface temperature of the heating table in the first heating zone S1

T6 surface temperature of the heating table in the first heating zone S2

T7 Surface temperature of the heating table in the first heating zone S3

T8 surface temperature of the cooling table

T9 ambient temperature when cutting or winding the

Prepreg strand

T10 refrigerator temperature of the conditioned space 29

T11 Ambient temperature when stacking prepreg sections

T12 Ambient temperature during intermediate storage of raw leaf springs

T13 temperature of the raw leaf spring during pressing

T14 Temperature of the raw leaf spring in the tempering furnace

T15 temperature of the leaf spring during finishing, test bench test and

Outgoing inspection

V speed

WE goods receipt

Claims

claims

1. A method for producing leaf springs (28) from a fiber composite material (11) with the following method steps ".

Covering the upper side and the underside of a fiber strand (2), which consists of at least parallel aligned fibers, with at least one Abdeckmaterialbahn (3, 4),

Wetting the fibers of the fiber strand (2) with a not yet hardened plastic matrix (14),

Heating the covered plastic matrix-covered fiber strand (2) to impregnate the fibers of the fiber strand (2) with the not yet hardened plastic matrix (14),

Cooling the covered plastic matrix-impregnated fiber strand (2),

Cutting the covered plastic matrix-impregnated fiber strand (2) into individual prepregs (11 ') or winding them into a prepreg roll (20),

Depositing a plurality of layers of prepregs (11) vertically one above the other on a convexly curved surface (22) to form a green leaf spring (23),

Cooling the green leaf spring (23) on a convexly curved surface (22),

- Pressing the green leaf spring (23) in a press (25) to a pressed raw leaf spring (23 '),

- Heating the pressed raw leaf spring (23 '), and

- Finishing the pressed raw leaf spring (23 ') to the finished leaf spring (28), wherein in all manufacturing steps predetermined temperatures (T) are set to the respective material or to the respective intermediate product, and wherein the respective temperatures (T) over predetermined Periods (.DELTA.t) are maintained.

2. The method according to claim 1, characterized in that the synthetic resin, the hardener and the accelerator of the plastic matrix (14) starting from a material temperature of T1 = 23 ⁰ C ± 10 ° C each separately within a period of Δt1 = 22 hours to 26 Hours at the following temperatures be brought: Resin T2 = 80 ⁰ C ± 10 ⁰ C, hardener T3 = 55 ° C ± 10 ⁰ C, accelerators T4 = 35 ⁰ C ± 1O ⁰ C.

3. The method according to claim 2, characterized in that the synthetic resin, the hardener and the accelerator of the plastic matrix (14) starting from a material temperature of T1 = 23 ° C + 10 ⁰ C each separately within a period of Δt1 = 24 hours following Temperatures are brought: synthetic resin T2 = 80 ° C ± 10 ° C, hardener T3 = 55 ° C ± 10 ⁰ C, accelerator T4 = 35 ⁰ C ± 10 ° C.

4. The method according to claim 1 and 2 or 1 and 3, characterized in that the synthetic resin, the curing agent and the accelerator to form the still liquid plastic matrix (14) are brought together, and then that later to the fiber strand (2) facing side at least one of two Abdeckmaterialbahnen (3, 4) are coated with the plastic matrix (14).

5. The method according to claim 4, characterized in that the Abdeckmaterialbahnen (3, 4) and the fibers of the fiber strand (2) prior to their coating or prior to their merging have a temperature of T1 = 23 ° C ± 1O ⁰ C.

6. The method according to at least one of claims 1 to 5, characterized in that the Abdeckmaterialbahnen (3, 4) and the fiber strand (2) over the convex curved surface (15) of a heating table (6) pulled and merged there.

7. The method according to claim 6, characterized in that covered with the coated Abdeckmaterialbahnen (3, 4) fiber strand (2) along a first heating zone (S1) of the heating table (6) to a temperature of T5 = 75 ° C + 10 ^0th C, along a second heating zone (S2) of the heating table (6) to a temperature of T6 = 110 ° C ± 10 ° C and along a third heating zone (S3) of the heating table (6) to a temperature of T7 = 120 ° C + 10 ⁰ C is brought.

8. The method according to claim 6, characterized in that covered with the coated Abdeckmaterialbahnen (3, 4) fiber strand (2) along a first heating zone (S1) of the heating table (6) to a temperature of T5 =

10fJ ⁰ C ± 10 ⁰ C, along a second heating zone (S2) of the hot-stage (6) to a temperature T6 = 150 ⁰ C ± 1O ⁰ C, and along a third heating zone (S3) of the hot-stage (6) to a temperature of T7 = 80 ⁰ C ± 10 ⁰ C is brought.

9. The method according to claim 7 or 8, characterized in that the covered and with the plastic matrix (14) impregnated fiber strand (2) in the region of the third heating zone (S3) at its top by the bearing force (F3, F4, F5) of at least a smoothing roller (7, 8, 9) is smoothed.

10. The method according to claim 7 or 8 or 9, characterized in that the covered and with the plastic matrix (14) impregnated fiber strand (2) after leaving the heating table (6) over the surface of a cooling table (10) is guided on the the temperature of this fiber strand (2) is cooled to T8 = 18 ⁰ C + 4 ° C.

11. The method according to claim 7 or 8 or 9, characterized in that the covered and impregnated with the plastic matrix (14) fiber strand (2) after leaving the heating table (6) over the surface of a cooling table (10) is guided on the the temperature of this fiber strand (2) is cooled to T8 = 8 ⁰ C ± 4 ° C.

12. The method according to claim 10 or 11, characterized in that the cooled, covered and impregnated fiber strand (2) as a prepreg strand (11) cut into individual prepreg pieces (11 ') or to a prepreg roll (20) at an ambient temperature of T9 = 23 ° C ± 1O ⁰ C is rolled up.

13. The method according to at least one of claims 1 to 12, characterized in that the prepreg pieces (11 ') or the prepreg roller (20) at a temperature of T10 = 8 ⁰ C + 4 ⁰ C / -2 ° C for a period of Δt3 = 12 hours in an air-conditioned space (29) are stored.

14. The method according to claim 13, characterized in that cut prepreg pieces (11 ') at a temperature of T11 = 21 ° C ± 3 ⁰ C within a period of Δt4 = 30 minutes to Ron leaf springs (23) stacked vertically one above the other become.

15. The method according to claim 14, characterized in that the raw leaf springs (23) in an air-conditioned space (24) at a temperature of

T12 = 21 ° C ± 3 ° C for a period of Δt5 = 24 hours are stored largely free of condensate.

16. The method according to claim 14 or 15, characterized in that the Ron leaf springs (23) in the press (25) at a temperature of T13 = 125 ° C to 180 ⁰ C in a period of Δt6 = 35 minutes to 42 minutes be pressed.

17. The method according to claim 16, characterized in that the overall Ron pressed leaf springs (23 ') are exposed in a tempering furnace (27) a temperature of T14 = 160 ⁰ C for a period of Δt7 = 4 hours.

18. The method according to at least one of claims 14 to 17, characterized in that the raw leaf springs (23) in the conditioned space (24) and / or in the annealing furnace (27) are each mounted on a convexly curved base (22) whose surface geometry is largely consistent with the shape (26) of the press (25).

19. The method according to claim 18, characterized in that the pressed raw leaf springs (23 ') cooled after the temperature treatment in the annealing furnace (27) to a temperature of T15 = 23 ° C ± 10 ° C and within a period of Δt8 up to Δt10 = 10 minutes of completion, a submission on a test bench and a goods issue inspection.