WO2013026801A1

WO2013026801A1 - Method for producing a structural element made of a pre-impregnated composite fibrous material, structural element thus produced and joining mold

Info

Publication number: WO2013026801A1
Application number: PCT/EP2012/066131
Authority: WO
Inventors: Gerald Possarnig
Original assignee: C6 Gmbh
Priority date: 2011-08-19
Filing date: 2012-08-17
Publication date: 2013-02-28
Also published as: AT511885A2; AT511885B1; EP2744642A1; AT511885A3

Abstract

The invention relates to a method for producing a structural element from components (12a through 12e, 16, 17, 18) made of pre-impregnated composite fibrous material (prepreg) having a hollow, semi-hollow, shallow or U-shaped or similar cross section, which are shaped and hardened under pressure and heat by means of at least one inserted flexible sealing membrane (15) in a molding tool. Either the already pre-formed components (12a through 12e, 16, 17, 18) of the structural element are deposited on a joining mold (10, 11) or blanks made of prepreg are formed into components therein, the components (12a through 12e, 16, 17, 18) being removed from the joining mold (10, 11) with the inserted sealing membrane(s) (15) and transferred into the molding tool.

Description

Method for producing a component from a preimpregnated fiber composite material, component and joining form produced in this way

The invention relates to a method for producing a component from hollow, semi-hollow, shell-shaped or U-shaped and similar components made of preimpregnated fiber composite material (prepreg), which is shaped and cured by means of at least one inserted sealing membrane in a mold under pressure and heat become.

For heavily loaded components of vehicles and machines, it is common

Continuous fiber-reinforced flat semi-finished products made from carbon fibers or other high-strength fibers with plastics as matrix material to form layered composite materials. In this case, the largest possible proportion of the component should be formed from fibers, as these have the load-bearing function, wherein the fibers should be aligned in the direction of the load on the components. According to the state of the art, these requirements are met by the best method in which the flat semi-finished fiber products are formed by layering (lamination). In one of the conventional methods, dry semifinished fiber products are deposited on a preform, wherein the individual layers are fixed by textile processing, such as sewing, braiding or weaving, or by a superficial application of a binder to a so-called preform, so that a transfer of the molded

Layer structure of the preform in the mold is possible. In this known as RTM process method, the cavities between the reinforcing fibers are filled in the mold with a suitable liquid plastic, hereinafter solidified by crosslinking or cooling, wherein a solid composite material is formed from fibers and plastic.

In another conventional method, a deposit of pre-impregnated takes place

Semi-finished fiber products (so-called prepregs) in suitable molds. In most cases, prepregs with a sticky surface are used to ensure adhesion of the individual layers to one another. Separate process steps for fixing the

Layer structure are therefore not required. Since the impregnation with viscous synthetic resins limits the mobility of the fibers in the semifinished product, a large number of methods has been developed which propose a transformation of the prepreg, individually or in several layers, into components of the components. In many cases, partial consolidation of the synthetic resins in the prepreg is recommended for consolidation and stabilization of the components. It is also common to these known methods that a deposit or draping of the impregnated components takes place directly in or in the mold.

From DE 198 13 104 AI discloses a process for the production of fiber composite components located in an evacuable vacuum film, fibers comprising preform and a matrix material, wherein between the vacuum film and the fiber composite component to be produced, a porous membrane is introduced, whose pores are dimensioned such that Air can escape unhindered and the liquid matrix material is retained. The preform is either as semi-finished fiber and the

Matrix material in liquid form or as semi-finished fiber and the matrix material used as a film or as preimpregnated with matrix material semifinished fiber products.

From DE 601 02 741 T2 there is known a method of forming an article from layers of uncured resin impregnated fiber composite using a forming apparatus having a forming tool and a frame providing an opening in which a Membrane is introduced. The layer or layers of the composite material are draped over the forming tool, the membrane is applied over the composite material layers and it becomes a vacuum is applied between the membrane and the forming tool. Thus, this is a method of membrane vacuum forming a layered fiber composite part in which the composite material layers are draped directly on the mold. DE 10 2009 044 834 AI deals with a method for producing a preform for a fiber composite component. The preform is made by first forming a fiber reinforcement layer, applying a binder by spraying it with the binder

Cold-formed fiber reinforcement layer is heated and the reshaped binder-provided fiber reinforcement layer is heated and then cooled.

As already mentioned above, it is the use of prepreg

Semi-finished fiber products, so-called prepregs, customary either to deposit preformed components directly in the mold, or to drape prepreg blanks directly into or onto the mold. The storage of preformed components or the draping of blanks from prepreg is possible only in cooled molds, so it is necessary to the mold after each of a previous

Cure cooling process to complete the next component can. It is therefore also necessary to then reheat the mold. The consolidation and curing process requires a mold temperature of up to 200 ° C for crosslinking matrix resins, and for thermoplastic resins up to 400 ° C, so energy consumption can be significant. During the curing process, the component must be subjected to hydrostatic pressure and, if necessary, kept under vacuum. The mold must therefore be designed so that it

Process conditions during curing of the component withstands. There are therefore temperature-resistant materials in thick-walled construction necessary, which cause high production costs for the mold. For economic reasons, therefore, the time in which the mold is bound for the manufacture of a component should be kept as short as possible. Here is where the invention, whose task is to improve a method of the type mentioned in such a way that the time in which the mold is quasi bound for the production of a component is kept as short as possible.

This object is achieved according to the invention in that either the already preformed components of the component are deposited or blanks are formed from prepreg to components on a joining form, wherein the components are removed with the / the inserted sealing membrane (s) of the joining mold and transferred into the mold ,

In the method according to the invention therefore finds in the mold only the

Consolidation and networking of the matrix resin instead. In this case, the sealing membrane, which is located on the formabgewandeten surface of the component, by air, steam, hot water, oil or the like subjected to hydrostatic pressure and at the same time the mold is heated to accelerate the consolidation and networking or perform. The mold therefore needs after the end of a

Curing process not or only slightly to be cooled to remove the finished component. After removal, the assembled in the joining form components of the next component together with the sealing membrane or the

Sealing membranes are transferred to the mold, without this before

cool. According to the invention, therefore, the mold is immediately after the end of a curing process again for the production of the next component to

Available, a time-consuming and energy technically unfavorable cooling and

Heating the mold omitted.

The method according to the invention uses a joining mold which

Recesses whose inner contours correspond to at least portions of the outer contours of the preformed components or the components formed by draping. In one embodiment of the invention, the joining mold is in two parts with a

Molded upper part and a lower mold part executed. A two-part joining form is especially advantageous for creating or joining hollow components or molded parts. Depending on the configuration of the component or the components of the component, the sealing membrane (s) is / are already inserted into the components during preforming of the components, in particular in the case of hollow body-shaped components. Alternatively, it is possible to insert the sealing membrane (s) in the components in the joining form.

The components can be preformed from blanks of gelatinous prepreg. In this case, the blanks of the prepreg after removal of the release films, which prevent sticking of the prepreg during storage on rollers, formed in a known manner, for example by draping, winding around a mandrel, stacking and the like to component components. The components can also be preformed from blanks of dry prepreg and under the action of heat. Both when producing preformed components and when draping blanks in the mold, the components can be made from one or more layers of prepreg. The method according to the invention therefore permits the production of components and components designed in many different ways.

It is advantageous if the components in the joining form are in contact with each other

Overlap shock areas. As a result, the components are joined together to form the component. In the case of sticky prepregs, the overlap is sufficient to easily transfer the component from the joining form into the molding tool. Components made of dry prepreg can additionally be glued together at the overlapping areas.

In a preferred embodiment of the invention, components which are closed on the outside can be produced in such a way that, after the positioning of the sealing membrane, they are deposited on the joining form, open at the top and, for example, U-shaped in cross section

Components each have a further component with, for example, also U-shaped, semi-hollow or similar cross-section is positioned so that closed hollow components are formed.

Alternatively, components of overlapped wound prepreg can be preformed into hollow bodies.

The sealing membrane is inventively designed so that they

can cover the inner side of the components of the component which faces away from the form. It can be an arbitrarily shaped hollow body.

In the form of joining, it can be advantageously tested by pressurizing the sealing membrane for tightness.

The invention further relates to a component which is produced by the method according to the invention and further a joining mold for assembling or draping preformed in cross-section hollow, semi-hollow, shell or U-shaped and the like components of a component of pre-impregnated fiber composite material, with recesses whose Inner contours correspond to at least portions of the outer contours of the components.

Other features, advantages and details of the invention will be apparent from the

Drawing which schematically illustrates embodiments of the invention, described in more detail. 1 shows a flow chart for the sequence of the method according to the invention.

2 shows a joining mold according to the invention and preformed component components,

3 is a plan view of the joining mold with positioned component components,

4 is a section along the line AA of Fig. 3, FIGS. 5 to 7 are sectional views similar to FIG. 4 with further embodiments of the invention, FIG. 8 is a sectional view of a molding tool with an inserted component according to FIGS. 7 and

9 shows a view of a two-part joining mold with component transfer into a molding tool. The method according to the invention is suitable for producing components which are hollow, semi-hollow, U-shaped, cup-shaped and the like in cross-section

Components can be joined together.

1 illustrates the sequence of a preferred embodiment of the method according to the invention for the production of components from preimpregnated fiber composite material. In the first process step (step 1 in FIG. 1), the prepreg is first of all

Fiber composite material, usually called prepreg formed. The fiber composite material consists of one layer or several layers of fiber fabric or fiber fabric and is preimpregnated with a matrix resin. The fiber fabric or fiber fabric may be made

Glass fibers, carbon fibers, synthetic fibers, natural fibers, hybrid fibers or

Combinations of the mentioned fibers are made. The matrix resin used for the impregnation may be solid, liquid or gel-like tacky and is an incompletely crosslinked duroplastic or a thermoplastic. Resins based on epoxides, vinyl esters, unsaturated polyesters, phenols, polyurethanes or cyanate esters are predominantly used. The prepreg is thus a flat semifinished product made of reinforcing fibers and a sufficient amount of matrix resin for consolidation and curing and is provided in the form of webs, wound on rolls. If the matrix resin in the prepreg in liquid or gel-like sticky form before, from blanks of the prepreg, after removing the release films, which prevent sticking of the prepreg during storage on rollers, now in a known manner, for example by draping, winding around a mandrel , Stacking and the like component components are manufactured. Lies the matrix resin in an alternative embodiment of prepregs in solid form, blanks are softened from the prepreg by the action of heat such that a deformation of the sheet semifinished by bending, edge or deep drawing can take place to preformed components of the component to be produced. In either case, the blanks of the prepregs are made to have corresponding contours and the desired fiber orientation. These manufacturing capabilities of component components (step 2 in FIG. 1) are optional.

FIG. 2 shows, by way of example, a plurality of differently preformed components 12a to 12e which, when joined together, produce the component to be produced. In the next

Process step (step 3 in FIG. 1), the preformed components 12a to 12e, which consist of one or more layers of prepreg, are positioned in a joining mold 10. The joining mold 10 has mold cavities whose inner contours are executed at least largely in accordance with the outer contours of the preformed components 12a to 12e. In the embodiment shown in FIG. 2, the components 12a to 12e, which have a U-shaped cross section or substantially in each case, form a component which has a substantially rectangular frame and a connecting part which consists of the component 12e which comprises the two

Components 12a and 12c connects. The components 12a and 12c are with

From formations 14a and 14c for connecting positioning of the component 12d provided. All components 12a to 12e and the depressions in the joining mold 10 are adapted to one another such that the components 12a to 12e positioned in the joining form 10 can be joined together overlapping one another at their edge sections or join one another and jointly form the component. In this case, the components are produced in such a way that in the joining form 10 they are the mutual ones

Overlap areas can form. If the tackiness of the prepreg material is insufficient to give the component the necessary stability for the subsequent transfer of the joining form 10 into the molding tool, adhesive materials in paste or film form can additionally be used. According to an alternative embodiment of the invention, in which no preforming (step 2 in FIG. 1) takes place, corresponding blanks made of prepreg are draped in one or more layers in the joining form 10 and therefore joined together when being inserted into the component. The joining mold 10 is made of a material that allows easy removal of the

Components 12a to 12e allows, for example, plastic or aluminum. Alternatively, the insides of the wells may be appropriately coated or treated. Also possible is an embodiment of the insides with ribs,

Perforations and the like.

In the subsequent method step (step 4 in FIG. 1), a flexible sealing membrane 15 is inserted into the positioned (or alternatively draped) component components 12a to 12e. As shown in Fig. 3 in conjunction with Fig. 4, the sealing membrane 15 is an elongated, hose-like executed bellows made of elastic plastic or elastomer with a closed end 15 a. However, any embodiment of the sealing membrane 15 is conceivable, which results in one or more closed chambers and which allows the formabgewandten surface of the component with a hydrostatic pressure, the sealing membrane 15 is dimensioned and designed such that they

Completely cover surface facing away from the form (inside) of the component. As shown in FIG. 3, the sealing membrane 15 is led out of the joining mold 10 at a cut-out 10b at the edge of the joining mold 10. In the embodiment shown, the flexible

Sealing membrane 15 are continuously inserted into all components 12a to 12e. 4 shows, in section, the component 12b positioned in the joining mold 10 with the sealing membrane 15 inserted.

As shown in FIG. 5, 15 additional preformed components can be positioned on the inserted components after inserting the sealing membrane. Shown is a component 16a, which preformed in cross-section U-shaped component 12b covers, so that a component with a closed, in FIG. 5 by way of example approximately rectangular cross section is produced. FIG. 6 shows a further embodiment variant of a component component 17a in cross-section of the joining form 10 with a component component 17 already preformed in closed form. The component 17 is, for example, a hollow part which is approximately rectangular in cross-section and which consists of one or more prepreg layers (n) with overlapping ones Edge sections 17a preformed by winding over a mandrel or the like and then inserted into the joining mold 10. Inside the component 17 is the introduced

Sealing membrane 15 shown in section. In this case, the sealing diaphragm 15 is preferably already positioned in step 2, during the formation of the component 17, or subsequently introduced into the component 17 as an elongated "bag" closed at its one end.

Fig. 7 shows in cross section a component component 18 as a combination of in

Cross-section U-shaped, preformed or draped component 12b and a "wound" in this inserted component 17, as shown in Fig. 6.

The actual design of the component to be produced determines the design and number of its individual components, taking care that the joining mold 10 can be carried out accordingly. Depending on the complexity of the component, it may be necessary to use a plurality of sealing membranes and a plurality of joining molds 10. Depending on how the individual component components are positioned in the joining mold 10, the component components are transferred as a whole or in parts from the joining mold 10 into the mold which is designed in a conventional manner. in the

Forming tool is the consolidation of the component by inserting a

hydrostatic internal pressure in the sealing membrane or the sealing membranes 15 and carried out under heating of the mold components, so that the matrix resin is crosslinked or cured (step 6 in Fig. 1). The component is firmly assembled from its component components and removed after networking as a whole of the form. The pressure membrane 15 or the pressure membranes can be removed if necessary after removal of the component. Fig. 8 shows schematically a section through a closed mold with upper mold part 19 and lower mold part 20 with a trained in this Mold cavity for receiving the joined in the mold 10 component. Shown is a component 18 according to FIG. 7.

In particular, in the production of hollow bodies or components with

Hollow body sections, it is advantageous to use an at least two-part joining mold 11, in particular with a Fügeformunterteil I Ia and a joining mold upper part 1 lb, as shown by way of example in Fig. 9. The joining mold bottom I 1 a, which in the example corresponds to the joining mold 10 shown in FIG. 2, and the joining mold top 1 lb are provided with mold cavities whose inner contours correspond to the outer contours of the molded part or component 21 to be formed. FIG. 9 further shows the component 21 joined in the joining form 11, which is a hollow body with several sections, analogous to the embodiment shown in FIGS. 2 and 3. Also visible is the pressure port 15b of the introduced, not visible here sealing membrane 15. In Fig. 9 is also a

Mold with an upper part 22 and a lower part 23 shown. As shown, the molding tool, which may also have more than two parts, at least substantially coincide with the joining mold 11. The two arrows in Fig. 9 illustrate the transfer of the joined component 21 of the joining mold 11 in the

Mold. The inventive method makes it possible to keep the time in which the mold is used for the production or curing of the component very short. The mold does not need to be cooled or only slightly cooled after the end of the curing process to remove the finished component. The component components or blanks already assembled in the joining form can be transferred together with the sealing membrane (s) into the molding tool without this being cooled down. The invention therefore allows the mold after the end of a

To provide curing process after a very short time for the production of the next component, as a time-consuming cooling and heating of the

Forming tool can be omitted. In the or the joining forms can already have a

Assembly of the components for the next component take place while the

Forming tool for the curing process is in use. It is therefore also the required Energy use compared to the known methods much lower, since an intermediate temperature of the mold requires a much lower energy consumption than cooling with subsequent heating.

References list

1 to 7. process interface

12a to 12e. component

10. Add shape

11. Add shape

I, Ia. Add mold part

I Ib. Add mold top

14a. formation

14c. formation

15. sealing membrane

15a. closed end

15b pressure connection

10b section

16a component

17 component

17a edge section

18 component

19 top part

0 lower part

1 component

2 top part

3 lower part

Claims

claims

1. A method for producing a component from in cross-section hollow, semi-hollow, shell or U-shaped and the like components (12a to 12e, 16, 17, 18) of pre-impregnated fiber composite material (prepreg), which is brought into shape and by means of at least one inserted flexible sealing membrane (15) are cured in a mold under pressure and heat,

characterized,

that on a joining form (10, 11) either the already preformed components (12a to 12e, 16, 17, 18) of the component are deposited or blanks are formed from prepreg to components, the components (12a to 12e, 16, 17, 18 ) with the inserted sealing membrane (s) (15) of the joining form (10, 11) and transferred into the mold.

2. The method according to claim 1, characterized in that the joining form (10, 11) recesses whose inner contours at least partial areas of

Outer contours of the preformed components (12a to 12e, 16, 17, 18) and the components formed by draping correspond.

3. The method according to claim 1 or 2, characterized in that the joining form (11) is designed at least in two parts and in particular a top mold (I Ib) and a lower mold part (I Ia).

4. The method according to any one of claims 1 to 3, characterized in that the sealing membrane (s) (15) is already inserted during preforming of the components in this or are.

5. The method according to any one of claims 1 to 3, characterized in that the sealing membrane (s) (15) is inserted in the in the joining form (10, 11) located components or be.

6. The method according to any one of claims 1 to 5, characterized in that the components are preformed from blanks of gel-like sticky prepreg.

7. The method according to any one of claims 1 to 5, characterized in that the components are preformed from blanks of dry prepreg and under the action of heat.

8. The method according to any one of claims 1 to 7, characterized in that the components are produced from one layer or from several layers of prepreg.

9. The method according to any one of claims 1 to 8, characterized in that the components in the joining form (10) overlap each other at their joint areas.

10. The method according to claim 9, characterized in that components

dry prepreg are glued together at the overlapping areas.

11. The method according to any one of claims 1 to 10, characterized in that after positioning the sealing membrane (15) in the joining form (10) deposited open-top, in cross-section, for example, U-shaped components each having a further component (16a) with, for example also U-shaped, semi-hollow or the like cross-section is positioned so that closed hollow components are formed.

12. The method according to any one of claims 1 to 10, characterized in that components of overlapping wound prepreg hollow body preformed.

13. The method according to any one of claims 1 to 10, characterized in that the sealing membrane (15) is designed such that it is the formabgewandten

Inner sides of the components (12a to 12e, 16, 17, 18) of the component covered.

14. The method according to any one of claims 1 to 10, characterized in that the sealing membrane (15) is an arbitrarily shaped hollow body.

15. The method according to any one of claims 1 to 14, characterized in that the sealing membrane (15) in the joining mold (10) is checked by pressurization for leaks.

16. component which is produced by the method according to one or more of claims 1 to 15.

17. Joining Form (10, 11) for joining or draping preformed in

Cross-section hollow, semi-hollow, shell or U-shaped and the like components (12a to 12e, 16, 17, 18) of a component of pre-impregnated fiber composite material, with recesses whose inner contours at least

Partial regions of the outer contours of the components (12a to 12e, 16, 17, 18) correspond.

18. joining mold (11) according to claim 17, characterized in that it is designed at least in two parts and in particular a top mold part (I Ib) and a

Mold lower part (I Ia) has.