Source: https://patents.google.com/patent/EP2492074B1/en
Timestamp: 2020-05-27 01:22:55
Document Index: 118047609

Matched Legal Cases: ['art 14', 'art 14', 'art 14', 'art 15', 'art 14', 'art 14', 'art 21', 'art 21', 'art 21', 'art 21', 'art 24', 'art 24', 'art 21', 'art 24', 'arts 21', 'art 21', 'art 24']

EP2492074B1 - Method for producing a leaf spring as fibre compound component - Google Patents
Method for producing a leaf spring as fibre compound component Download PDF
EP2492074B1
EP2492074B1 EP12156375.3A EP12156375A EP2492074B1 EP 2492074 B1 EP2492074 B1 EP 2492074B1 EP 12156375 A EP12156375 A EP 12156375A EP 2492074 B1 EP2492074 B1 EP 2492074B1
EP12156375.3A
EP2492074A1 (en
2011-02-28 Priority to DE102011012654A priority Critical patent/DE102011012654A1/en
2012-02-21 Application filed by Benteler SGL GmbH and Co KG filed Critical Benteler SGL GmbH and Co KG
2012-08-29 Publication of EP2492074A1 publication Critical patent/EP2492074A1/en
2014-03-19 Publication of EP2492074B1 publication Critical patent/EP2492074B1/en
239000000835 fiber Substances 0 title claims description 176
The invention relates to a method for producing a leaf spring as a fiber composite component for a motor vehicle according to the features in the preamble of claim 1.
Composites generally have better mechanical properties than the components composing them. The interactions occurring in the combination of the mostly two main components enable an idealized absorption of the internal forces which occur when a component made of a composite material is loaded. Fiber composite materials, in particular, advantageously have a high weight-related strength and rigidity of the components produced therefrom.
As a basis serve artificial or natural fibers, which are processed individually or as a fiber bundle (roving) and as a textile fabric. In combination with a matrix of hardening resin surrounding the individual fibers, components which are highly stressable and open up an almost unlimited field of application arise. Those known in the art Manufacturing capabilities are based on the use of resin-impregnated fibers which are combined in a forming tool under the influence of pressure and heat to form a fiber composite component.
The DE 10 2006 052 137 A1 discloses a method for producing a leaf spring from a fiber composite material. The fiber composite comprises individual fibers and a thermosetting resin matrix surrounding the fibers, wherein the resin is cured in a die.
The individual fibers are first wetted in the form of a fiber strand with a non-hardened plastic matrix, which penetrates under the influence of heat in the fiber strand and thus infiltrated. By subsequent cooling, the premature reaction of the resin is prevented, whereupon the thus-infiltrated fiber strand is cut to form individual prepregs. The individual prepregs are stacked on top of each other in a forming die and hardened under pressure and heat. Subsequent finishing, the finished leaf spring is created.
The measures required here for infiltration and cooling of the fiber strand make consuming. In particular, the cooling must be ensured until shortly before use of the prepregs to obtain the binding properties of the resin. In addition, the handling of the prepregs with their unbound resin is generally more difficult. Furthermore, the measure of the layering of the sticky prepregs also requires a high degree of precision in order to place them on one another as congruently as possible and with little air entrapment. In particular, the layers is therefore associated with an increased amount of time. Moreover, the end regions of the component also have to be given a high level of attention in order to obtain as far as possible no notch effect or exposed ends of the fibers, which can lead to a weakening and thus shortened service life of the fiber composite component.
From the US 2005/086916 A1 a method for producing a leaf spring as a fiber composite component for a motor vehicle is known. To produce the leaf spring, the individual fibers are initially in the form of at least two textile layers provided and stacked, after which they are fixed to a dry preform. This preform is then infiltrated with resin in an RTM cavity and cured.
By the DE 103 21 824 A1 For example, a method of casting structural composites is known. These may be, for example, leaf springs for chassis components. To produce a preform is placed in a mold, closed the mold and built in the mold via a vent shaft a vacuum. Subsequently, a resin material is injected into the mold through a resin inlet until it at least partially fills the vent. The vacuum generation is then stopped. Subsequently, a positive pressure is applied via the vent shaft and forced at least some resin back into the mold from the vent shaft. Thereafter, the curing of the resin and the removal of the finished component takes place.
The DE 34 34 522 A1 describes a method for producing molded parts, preferably leaf springs made of fiber-reinforced reaction resins having a fiber mass fraction of 50 to 80% by inserting pre-oriented fiber reinforcing materials into a mold, sealing the mold, filling the reaction resin in the mold, reducing the volume of the mold interior by displacing the mold Residual air, curing of the resin and demolding of the cured molding.
Furthermore counts by the DE 101 61 773 A1 a method for producing a three-dimensionally shaped fiber composite plastic component of the prior art. To produce a three-dimensionally woven fiber semi-finished product is first placed in a fixing mold and then fixed by a fixing agent in its three-dimensional shape. As a result, the semi-finished fiber can no longer deform during the further manufacturing process. The fixing agent may be in liquid or powder form and is applied to the semi-finished fiber with a suitable tool such as a spray gun or a spreader.
Against this background, the production of leaf springs as fiber composite components with regard to industrial economic processes still offers room for improvement.
The present invention is based on the object to improve a method for producing a leaf spring as a fiber composite component for a motor vehicle to the effect that simplifies the handling of the resin to be infiltrated fibers and the production can be done more economically. Furthermore, a leaf spring produced by this method will be shown, which is made more economical overall production and in particular more precisely in their marginal and end areas.
The solution of the procedural part of the task according to the invention in a method for producing a leaf spring as a fiber composite component for a motor vehicle according to the measures of claim 1.
Hereinafter, a method for producing a leaf spring as a fiber composite component for a motor vehicle is shown, which comprises individual fibers and a matrix surrounding the fibers of a thermoplastic or thermosetting resin. The resin infiltrating resin is cured. According to the invention, the fibers are provided in the form of at least two textile layers and stacked on top of each other. The textile layers layered in this way are molded inside a press-forming tool and thereby fixed to a dry preform by a binder applied dry on at least one of the textile layers. The binder is first applied to a textile web, from which the individual textile layers are cut. The dry preform is then infiltrated with the resin in an RTM cavity and cured.
The hardening of the resin within the RTM cavity takes place at least until a loadable degree of hardness of the fiber composite component to be removed from the RTM cavity is achieved. The case achieved hardness of the resin is at least sufficient to allow for further handling of the fiber composite component no plastic changes in shape.
The particular advantage is the dry handling of the fibers throughout the process. The actual infiltration of the fabric from fibers takes place only within the RTM cavity, from which the initially liquid resin is removed dry as a fiber composite component. As a result of the measure of impregnation and cool storage of the impregnated textile layers, which are omitted in this case, they are only moved dry outside the tools as a preform, which makes their handling considerably easier.
An important aspect of the invention is the dry applied binder, by which the individual textile layers are fixed in their already similar to the final shape of the leaf spring shape for preform. The dry preforms produced in this way can be stored and moved without separate requirements for the ambient temperature or retention time.
Depending on the requirement, the binder can only be applied to the textile layer in certain areas. In an advantageous manner, the binder is applied to a surface of the textile layer to be designated as a top side in the stacked state. In this case, the binder can be present for example in powder form or as granules, which rests on the top of the textile layer. The order taking place on one side of the textile layers Order of the binder can be omitted, for example, in the uppermost lying textile layer, as this already rests on the underlying textile layer and thus on their provided with the binder top.
The binder is intended to bind at least single fibers of the textile layers in some areas by adhesive or cohesive forces per se. Due to the binder, the textile layers lying on top of one another are at least partially glued together. The application of the binder to the individual textile layers can be done by contact or non-contact.
The order of the binder can be done for example by spreading, spraying or rolling.
Advantageous embodiments of the basic concept of the invention are content of the dependent claims 2 to 11.
The binder can be applied to individual textile layers. The binder can basically be applied nationwide or only partially on the textile web. The type of order depends on the form to be created, whereby flat areas remain dimensionally stable even with only a local order, while topographically demanding courses require a full-surface order.
In this case, individual areas can also be provided with different amounts of binder. Furthermore, the order may consist of a single binder or different binders, the different binders are applied specifically to individual areas of the textile web. Thus, for example, different strengths can be adapted to the local requirements.
The individual textile webs can have a uniform contour. Furthermore, the individual textile webs can also have a divergent contour, whereby local elevations or depressions of the entire textile staple can be adjusted solely by stacking the different textile webs.
In particular, areas of the finished fiber composite component of different thicknesses can be produced by, for example, laying down a narrower textile web in a middle region of a textile web, as a result of which the middle region of the fiber composite component is thickened. Also, different textile webs can already be used in their respective thickness. The thicker textile webs can have either multiply crossed fibers or a total of fibers with a larger diameter.
The individual textile layers can basically have the structure of a fabric or a fabric. To produce a fiber composite component and textile layers of a fabric or a scrim can be combined. As scrim, the textile layers preferably consist of several layers of fiber rovings arranged in parallel, the individual layers being in their respective Fiber direction differ from each other. The individual layers can be interconnected.
The fabric layers in the form of a woven fabric are textile fabrics which comprise at least two crossed fiber systems having at least two orthogonal or deviating courses.
The textile web used can already be designed as a single-layer or multi-layer, so that the textile layers separated from this textile web are used directly in multiple layers or provided with separation of their individual layers with the binder and stacked.
The invention provides that the binder arranged at least in regions between individual textile layers is melted by heating within the press-forming tool. The particular advantage here lies initially in the dry application of the binder. Due to the dry and in this context non-adhesive consistency of the binder this is simplified in its handling. Any surpluses can be easily removed from adjacent components or surfaces of the tools used and premises. The actual adhesive properties are only released by the reactivation of the binder, which takes place through the use of heat.
For this purpose, the press-forming tool preferably has at least one tempering unit, by means of which the binder is heated and thus melted. The melting of the binder can in this case also be targeted locally, wherein the temperature control unit only partially heated the binder. Also conceivable is a successive heating of the binder, with individual regions being heated one after the other. The successive heating preferably takes place during the shaping of the textile layers, as a result of which individual regions, in particular in the case of complicated spherical shapes, can smoothly slide past one another and be aligned without being impeded by the molten binder. Such areas are preferably targeted only after their shaping heated over the temperature control unit, whereby here too the binder is melted and the textile layers are fixed together.
Depending on the type of binder used, the actual fixation of the preform can also be done by cooling the molten binder. For this purpose, the binder is cooled after its melting, either over the entire surface or specifically locally, whereby the binder is at least partially fixed and the textile layers together. Similarly to the heating process, the cooling can also take place successively and in dependence on the particular shape of the preform.
According to the invention, a fiber composite blank is separated from the preform thus created, in particular punched out. In principle, the separation of the fiber composite blank from the preform can also be carried out via other dividing measures. Conceivable for this would be, for example, a multi-stroke cutting along the contour of the fiber composite blank. Even if the punching enables a very economical separation of the fiber composite blank from the preform that accompanies it with high precision, this can thus also take place via other mechanical tools or, for example, also thermal separation methods (eg electric arc, laser).
The fiber composite blank cut out of the preform has an extremely precise contouring, which is achieved independently of the congruence of the fiber ends achieved previously during stacking and shaping of the textile layers. In combination with the shaping already contained in the preform, the fiber composite blank has a consistently high quality with regard to the alignment and contouring of its textile layers, more particularly the individual fibers.
The fiber composite blank cut out of the preform is infiltrated with the resin within the RTM cavity and cured. Due to the precise contouring of the fiber composite blank, it can be positioned very precisely within the RTM cavity, so that individual and constant edge spacings of the fibers and fiber ends to the final shape of the leaf spring can be maintained.
The RTM cavity is preferably a closed, in particular solid tool, whereby the fiber composite blank is infiltrated with the resin and hardened in the course of a Resin Transfer Molding (RTM) process. In this case, the resin is injected into the closed RTM cavity, more precisely in its shaping area (cavity) with pressure, where it is cured under the influence of heat and pressure.
The introduction of the resin into the RTM cavity is carried out under high pressure, so that the fiber composite blank consisting of the individual textile layers is completely infiltrated with the resin. Here, the individual fibers are embedded in a matrix of thermosetting or thermoplastic resin, after which the actual curing can take place.
To avoid possible air pockets in the cavity of the shaping area this is preferably evacuated before. Due to the reduced atmospheric pressure within the shaping area, the resin can also be brought to higher regions of the cavity, whereby it is completely filled with resin. In combination with the applied pressure, the resin is thus pressed and / or sucked into all areas of the cavity.
Advantageously, the resin is injected centrally into the cavity of the RTM cavity. Due to the central injection of the resin into the cavity, all areas of the fiber composite blank are uniformly infiltrated with the resin.
Since the fiber composite blank has been separated from the preform prior to its contact with the resin, the fiber composite component has no exposed or even cut fibers after curing of the resin. The exposed at the separation of the fiber composite blank ends of the fibers are completely covered with the resin, whereby they are protected from possible stress and the life of the fiber composite component shortening damage.
It is envisaged that the fiber composite blank can be tempered locally differently within the RTM cavity. Furthermore, it is provided that the fiber composite blank within the RTM cavity can be tempered locally variable. About the locally variable temperature of the fiber composite blank can predetermined temperature curves are driven within the RTM cavity, whereby the individual areas are hardened stress-free. In principle, the temperature control can be heating or cooling.
The fiber composite blank may be actively cooled after curing of the resin within the RTM cavity. In principle, the cooling can also take place outside the RTM cavity.
It is envisaged that the already infiltrated and hardened fiber composite blank outside the RTM cavity can be heated at least in regions by a heat source to a temperature of 80 ° C to 200 ° C. The already infiltrated and cured fiber composite blank is heated in particular to a temperature of 120 ° C to 130 ° C. Subsequent heating has the purpose of completely curing the resin. The heating is preferably carried out in a tempering furnace, within which one or more of the already infiltrated and pre-cured fiber composite blanks are heated. In principle, the heating can also take place via other heat sources which are suitable for heating the already infiltrated and pre-hardened fiber composite blank at least in regions in contact or without contact. The tempering can be done for example via infrared radiation, microwaves or induction in combination with ferromagnetic materials.
Depending on the requirement, the component thus obtained can subsequently be machined mechanically. For example, individual areas can be fed to a manual or automated grinding process.
The invention already provides for the stacking of the individual textile layers that the individual fibers of the textile layers or the textile layers themselves are formed of different materials. Thus, at least some of the textile layers can be formed, for example, from glass fibers or carbon fibers. In addition, at least one of the textile layers may be formed from ceramic fibers, aramid fibers or boron fibers and natural fibers or nylon fibers. Individual fibers of the textile layers can be formed specifically from a different material than the adjacent fibers, for example, a glass or Carbon fiber. Individual fibers may also be used as ceramic fiber, aramid fiber or boron fiber, as well as natural or nylon fiber. In principle, at least one fiber can also be formed from metal or one of the textile layers from metallic fibers.
It is envisaged that the resin will be injected centrally into the RTM cavity. The particular advantage lies in the uniform distribution of the resin within the cavity, whereby a complete infiltration of the individual textile layers is achieved. Due to the same distance of the respective end regions within the cavity a uniform distribution of the resin is made possible without any air pockets.
In a preferred embodiment, it is provided that different temperature levels are used for hardening and / or for cooling. Corresponding temperature levels can already be used in the press mold. In addition, different temperature levels can also be driven in the RTM cavity. As a result, the entire manufacturing process as well as the respective handling can be simplified during production.
The inventive method shows an extremely economical way of producing a leaf spring as a fiber composite component for a motor vehicle, which is significantly simplified in the handling of infiltrated with a resin fibers. All of the processes associated with the uncured resin take place within an encapsulated system, more closely within the RTM cavity, eliminating the costly handling and storage of already infiltrated fibers.
By producing a preform in which the individual textile layers are first fixed to one another via a binder, the individual fibers can first be exactly positioned and shaped outside the contact region with the resin. The production of the preform raises no special requirements for the congruent stratification of the individual textile layers, since the actual embedded in the matrix of the thermosetting or thermoplastic resin Fiber composite blank is first separated from the preform. By separating from the preform extremely clean and exact edge areas are created, which is achieved regardless of the previously used care in relation to the stratification of the individual textile layers.
The invention provides a leaf spring produced by the method described above as a fiber composite component for a motor vehicle, which comprises at least two textile layers of fibers and a matrix of hardened resin surrounding the fibers. The resin may be, for example, thermosetting or thermoplastic. Between the two textile layers, a dry applied binder is at least partially arranged. The binder may be a material different from the resin. In principle, the binder may also be a material that is identical to the resin, but the binder then has a different length of the molecular chains. Due to the different lengths of molecular chains, the binder has different properties relative to the resin depending on the particular temperature. The binder is intended to fix the textile layers already before their infiltration with the resin with each other. The resin itself is cured in an RTM cavity.
The ends of the individual fibers may be completely embedded in the resin. The edge regions of the individual textile layers, more precisely the ends of the fiber, have at the edge an at least partially constant spacing from the outer contour of the fiber composite component. Even if the fiber composite component is processed mechanically in regions, the machined regions do not have any open ends of the fibers.
Advantageously, at least 90% of the fibers arranged in the fiber composite component are aligned in the longitudinal direction of the leaf spring. Alternatively, in particular 95% of the fibers contained in the leaf spring may be aligned in the longitudinal direction thereof. Preferably, 99% of the fibers arranged in the leaf spring are aligned in their longitudinal direction. The fibers which are not aligned in the longitudinal direction of the fiber composite component preferably extend in its transverse direction.
The proportion of fibers oriented transversely to the longitudinal direction of the leaf spring can be from 0% to 2% of the basis weight of a textile layer. In a claimed only in one direction leaf spring this may only have unidirectional textile layers. The individual fibers can be arranged in the form of rovings, which are aligned only in the direction of the stress. The transverse fibers arranged transversely to the main direction serve to stabilize the longitudinal fibers. The material of the longitudinal and transverse fibers may be different from each other. Individual fibers may for example be formed from glass fibers or carbon fibers. Furthermore, individual fibers may also be formed as ceramic fibers, aramid fibers or boron fibers and natural fibers or nylon fibers. In addition, for example, yarns, metal threads or thermoplastic threads can be used as fiber. For a pure stabilization, the transverse fiber can be made of a weaker material than the longitudinal fiber. In particular, when increased transverse tensile stresses occur, the transverse fibers can also be formed from a material which absorbs higher tensile forces.
The leaf spring has as a fiber composite component in its cross section on a fiber content of 50% to 70%. In principle, the fiber content within the cross section of the fiber composite component can be 55% to 65%. The fiber composite component preferably has a proportion of fibers of 59% to 63% in its cross section. By an increased, the tensile stresses receiving fiber content within the fiber composite component increased tensile forces can be absorbed. In components subjected to bending, in particular in the case of a leaf spring, the proportion of fibers in the cross section of the fiber composite component may preferably be arranged in the edge region of the bending form that occurs, wherein the individual fibers absorb the tensile forces and the resin absorbs the compressive forces that occur on the opposite side.
The invention provides that at least one of the fibers is formed of a different material. In principle, the individual fibers and fiber bundles (rovings) or else the individual textile layers can be formed from different materials. Individual fibers may for example be formed from glass fibers or carbon fibers. Furthermore, fibers are also made For example, ceramic fibers, aramid fibers or boron fibers and natural fibers or nylon fibers conceivable. In addition, at least one fiber may be formed of metal.
With the disclosed invention, it is possible to produce within a short time and with high precision a fiber composite component which has no weak points with respect to possibly exposed ends of its fibers. Due to the necessary distance of the individual fibers from the edge regions of the fiber composite component, these are protected against mechanical stress. A possible mechanical processing of the fiber composite component is accompanied by the controlled edge distance without exposing the individual fibers.
Depending on the requirement, the finished leaf spring and the tools associated with its production may have geometries corresponding to the respective application and intended use. Thus, the finished leaf spring, for example, have individual cross-sectional variations which extend over their length and height and / or width. In particular, areas with a higher load can specifically have a larger cross-sectional area in this case in order to better absorb the forces that occur.
For the intended installation of the finished leaf spring this may have corresponding bearing eyes at their respective ends. The bearing eyes can for example be integrally formed on the fiber composite component itself. In principle, the bearing eyes can be provided, for example, as a preformed component in order to be incorporated into the fiber composite component within the manufacturing process of the leaf spring.
The invention will be explained in more detail with reference to some schematically illustrated in the drawings embodiments. Show it:
a schematic process flow for producing a fiber composite component according to the invention;
a textile pile in a side view;
a shaping tool in cut representation as well
a variant of a fiber composite component according to the invention in a cross section.
FIG. 1 shows four stations 1 - 4, which characterize a method for producing a leaf spring 5 as a fiber composite component. Station 1 serves to provide individual fibers in the form of individual textile layers 6. The textile layers 6 are separated from a textile web 7, which is unwound from a textile roll 8. During the unwinding of the textile web 7, this is provided with a binder 9. The binder 9 is applied dry on an upper side A of the textile web 7, whereupon the textile web 7 thus provided with the binder 9 is passed in a passage direction B underneath a separating device 10 and cut to form textile layers 6 provided with the binder 9. The thus separated textile layers 6 are received individually via a vacuum gripper 11, which is connected to a manipulator 12 in the form of a robot arm. The vacuum gripper 11 is constructed so that the recorded textile layer 6 is already adapted in one to the forming area of a press tool 13 in its bend.
The recorded textile layer 6 is pivoted into the press-forming tool 13 via the manipulator 12 of the following station 2, where it is deposited on a first tool lower part 14 of the press-forming tool 13. Depending on the component to be created, a plurality of textile layers 6 are thus stacked on the first tool lower part 14. As soon as the required number of textile layers 6 has been reached, the press-forming tool 13 is closed. For this purpose, the stacked fabric layers 6 are pressed together between the first lower tool part 14 and a first upper tool part 15. The textile layers 6 and the binder 9 connected thereto are heated via a first temperature control device 16 integrated in the press mold 13. The temperature may be, for example, from 80 ° C to 130 ° C. As a result, the binder 9 is melted within the die 13 by heating.
By melted binder 9, the individual textile layers 6 are joined together and glued into a preform 17. The preform 17 has an ajar to the finished leaf spring 5 shape. Once the binder 9 is melted within the mold tool 13, the individual textile layers 6 are fixed by cooling the molten binder 9 with each other. By cooling the temperature level is lowered from a high temperature required for melting to a lower temperature, for example to 60 ° C. The temperature required for the melting is for example at 80 ° C to 130 ° C. Cooling also takes place via the first temperature control device 16, which is integrated in the press mold 13.
The preform 17 thus obtained is subsequently transferred to station 3. For this purpose, the preform 17 is moved within the first tool lower part 14 under a punching tool 18 which separates out a precisely contoured fiber composite blank 19 from the preform 17. The separation of the fiber composite blank 19 from the preform 17 is carried out by punching.
Subsequently, the fiber composite blank 19 produced in this way is transferred to station 4, which contains an RTM cavity 20. For this purpose, the fiber composite blank 19 is taken out of the first lower tool part 14 and inserted into a second lower tool part 21 of the RTM cavity 20. The fiber composite blank 19 is inserted into a cavity 22 of the second tool lower part 21, which can be filled via a filling opening 23 arranged centrally in the second tool lower part 21 with a resin (not shown).
To produce the leaf spring 5, the RTM cavity 20 is now closed, wherein the inserted into the cavity 22 fiber composite blank 19 between the second tool part 21 and a second tool upper part 24 of the RTM cavity 20 is included. The resin is then forced into the cavity 22 while a second tempering device 25 heats the RTM cavity 20. The RTM cavity 20 can be locally controlled by the second tempering device 25, wherein the local temperature also takes place successively over individual regions of the cavity 22 out.
Preferably, a negative pressure is generated by the cavity 22 is evacuated. The resin is filled into the RTM cavity 20 with such high pressure until the second tool upper part 24 indicates a lift-off. At this moment, the whole is Cavity 22 and in particular all textile layers 6 of the fiber composite blank 19 infiltrated with the resin. Subsequently, the curing takes place under appropriate pressure and temperature.
The leaf spring 5 to be removed from the RTM cavity 20 is at least partially heated by a heat source, not shown, to a temperature of 80.degree. C. to 200.degree. C., in particular to a temperature of 120.degree. C., for complete curing outside the RTM cavity 20 heated to 130 ° C. In this case, the resin is completely cured. The thus fully cured leaf spring 5 can then be machined in a manner not shown also in detail.
FIG. 2 shows a textile material stack 26 in a side view. Here, the textile layers 6 are stacked together with further textile layers 6a, the textile layers 6, 6a differing in their length. Depending on the design of the leaf spring 5 to be produced, the individual textile layers 6, 6a are first provided in a corresponding length C and width. The length C may be, for example, 2000 mm, while the width may be 600 mm, for example. The individual textile layers 6, 6a are stacked at a height D, for example, at 30 to 80 individual layers.
In the example shown here, the finished leaf spring 5 is replaced by the lying between the textile layers 6 shorter textile layers 6 a tapered ends E. By this configuration, for example, brackets can be arranged at the ends E, which integrate the leaf spring 5 in a motor vehicle not shown here , The in FIG. 2 It can be seen from the example shown that by varying the respective length C as well as the amount of textile layers 6, 6a stacked on top of each other, various shapes with respect to tapers or thickenings are also made possible in the regions located between the ends E.
FIG. 3 1 shows a section through the RTM cavity 20 formed from the second tool lower part 21 and the second tool upper part 24. The two tool parts 21, 24 together form the cavity 22. The cavity can, as shown, for example, have a curved and tapered to ends E1 shape. In the region of the ends E1 outlet openings 27 are arranged, which penetrate the RTM cavity 20 from the outside and open into the cavity 22. In the middle of the curved cavity 22, the filling opening 23 located between the outlet openings 27 is arranged, via which the resin is pressed into the cavity 22.
In order to carry out the Resin Transfer Molding (RTM) process, the fiber composite blank not shown here is made FIG. 1 inserted into the cavity 22 and enclosed by the second lower tool part 21 and the second upper tool part 24 of the RTM cavity 20. The resin is a duroplastic or a thermoplastic, which is pressed through the filling opening 23 under high pressure into the cavity 22. The filling opening 23 is arranged specifically in the middle region of the RTM cavity 20 so that the resin can be distributed in an ideal manner, whereby all textile layers 6, 6a are infiltrated.
The preferred pressure for the injection of the resin into the RTM cavity 20 is 80 bar to 100 bar, wherein the RTM cavity 20 via the not shown here second tempering 25 from FIG. 1 is heated to a constant 80 ° C. At this temperature, the resin has its highest viscosity, with other resins different temperatures and pressures are selectable.
The injection of the resin takes place until it emerges from the outlet openings 27 of the RTM cavity 20. At this time, the textile layers 6, 6a are impregnated with the resin within the cavity 22. Subsequently, the outlet openings 27 are closed. Subsequently, the cavity 22 is completely filled with the resin under high pressure until the RTM cavity 20 opens slightly due to the high internal pressure. As a result, all the fibers of the textile layers 6, 6a are completely embedded in the not yet cured matrix of the resin. Furthermore, there are no free fiber ends of textile layers 6, 6a outside the resin.
For the subsequent molding process, the RTM cavity 20 is subjected to full pressing pressure, which is maintained for a while. The additionally applied internal pressure corresponds to a few tenths to a few hundredths of the Output pressure. Depending on the resin used, the curing time is, for example, between 7 minutes and 60 minutes.
To accelerate the curing, a corresponding higher temperature is chosen.
Subsequently, the leaf spring 5 is removed from the RTM cavity 20 and placed for example in a tempering furnace. Here, the leaf spring 5, for example, completely cure at temperatures of 120 ° C to 130 ° C. After complete curing, this can be machined.
FIG. 4 in a variant, a leaf spring 5a in its cross section. The leaf spring 5a, which is formed in a manner not shown from the fibers of textile layers 6, 6a and the fibers surrounding the matrix as a thermosetting or thermoplastic resin, has reinforced in their edge regions F. Areas 28 on.
The reinforced portions 28 of the leaf spring 5a are formed in a manner not shown by high-strength fibers, for example by carbon fibers. As a result, the lateral rigidity of the leaf spring 5a is improved. The remaining fibers used can be formed, for example, from glass fibers.
textile role
first lower tool part
first tool top
first tempering device
Fiber composite blank
RTM cavity
second tool lower part
second tool shell
second temperature control device
Textile layer stack
Area, reinforced
Method for producing a leaf spring (5, 5a) in the form of a fibre composite component for a motor vehicle, which leaf spring has individual fibres and a matrix formed of a hardened resin surrounding the fibres, the fibres being provided in the form of at least two textile layers (6, 6a) layered on top of one another and fixed so as to form a dry preform (17) which is infiltrated with the resin and hardened in an RTM cavity (20), characterised in that the textile layers (6, 6a) are moulded inside a compression mould tool (13) and fixed so as to form the dry preform (17) by a binder (9) applied dry onto at least one of the textile layers (6, 6a), the binder (9) first being applied onto a textile web (7, 7a-b) from which the individual textile layers (6-6a) are cut.
Method according to claim 1, characterised in that the resin is injected into the centre of the RTM cavity (20).
Method according to either claim 1 or claim 2, characterised in that the binder (9) is melted inside the compression mould tool (13) by heating.
Method according to any of claims 1 to 3, characterised in that the preform (17) is fixed by cooling the melted binder (9).
Method according to claim 4, characterised in that a fibre composite blank (19) is separated from the preform (17), in particular by stamping.
Method according to claim 5, characterised in that the fibre composite blank (19) is infiltrated with the resin and hardened inside the RTM cavity (20).
Method according to claim 6, characterised in that the fibre composite blank (19) is tempered inside the RTM cavity (20) at locally different and/or locally varying temperatures.
Method according to either claim 6 or claim 7, characterised in that the fibre composite blank (19) is actively cooled inside the RTM cavity (20) after the resin has hardened.
Method according to any of claims 6 to 8, characterised in that, after being infiltrated and hardened, the fibre composite blank (19) is heated, at least in some regions, by a heat source to a temperature of from 80 °C to 200 °C, in particular to a temperature of from 120 °C to 130 °C, outside the RTM cavity (20).
Method according to any of claims 1 to 9, characterised in that the individual fibres of the textile layers (6, 6a) or the textile layers (6, 6a) themselves are made from different materials.
Method according to claim any of claims 1 to 10, characterised in that hardening and/or cooling is performed at different temperatures.
EP12156375.3A 2011-02-28 2012-02-21 Method for producing a leaf spring as fibre compound component Active EP2492074B1 (en)
EP2492074A1 EP2492074A1 (en) 2012-08-29
EP2492074B1 true EP2492074B1 (en) 2014-03-19
EP12156375.3A Active EP2492074B1 (en) 2011-02-28 2012-02-21 Method for producing a leaf spring as fibre compound component
DE102014115461A1 (en) 2014-10-23 2016-04-28 Benteler Sgl Gmbh & Co. Kg Method and device for producing a leaf spring
CN107553935B (en) * 2017-09-14 2019-11-05 安徽江淮汽车集团股份有限公司 A kind of FRP composite material plate spring ontology manufacturing process
CN107606014B (en) * 2017-09-17 2019-11-26 刘守银 A kind of leaf spring and its manufacturing process
DE102018121852A1 (en) * 2018-09-07 2020-03-12 Kraussmaffei Technologies Gmbh Process for the production of leaf springs in fiber composite construction and extrusion device
JPS6138021B2 (en) * 1979-03-23 1986-08-27 Nissan Motor
JPS6110304B2 (en) * 1980-12-27 1986-03-28 Hino Motors Ltd
AT392525B (en) * 1985-11-14 1991-04-25 Kofler Walter Dr Leaf spring made of fiber-plastic composite material
DE3780928T2 (en) 1986-12-19 1992-12-24 Takeda Chemical Industries Ltd A method of casting molds of faserverstaerkten plastics.
DE19959415C2 (en) 1999-12-09 2002-03-07 Wacker Polymer Systems Gmbh Process for pre-bonding fiber materials
WO2003056195A1 (en) * 2001-12-26 2003-07-10 Yamauchi Corporation Fiber-reinforced resin roll and method of manufacturing the roll
DE10228649A1 (en) 2002-06-26 2004-01-22 Bakelite Ag Process for the production of a fiber-reinforced product based on epoxy resin
CAMPBELL F C ED - CAMPBELL FLAKE C: "Manufacturing processes for advanced composites, passage", 1 January 2004, MANUFACTURING PROCESSES FOR ADVANCED COMPOSITES, ELSEVIER ADVANCED TECHNOLOGY, OXFORD, GB, PAGE(S) 331 - 341, ISBN: 978-1-85617-415-2, XP002565382 *
US20150069681A1 (en) 2015-03-12
JP2567828B2 (en) 1996-12-25 Molding sheet material and safety shoe toecap
Ref document number: 657339
Ref document number: 502012000462
Free format text: FORMER OWNER: BENTELER SGL GMBH & CO. KG, 33102 PADERBORN, DE