DE102015004743A1 - Effective production of workpieces, products made of material matrix structures or fiber composite material or fiber composite sandwich structures by means of thermoplastically deformable composite material starting materials - Google Patents

Abstract

Fiber material (1) from z. As fiberglass, carbon fibers as shown in Figure 1 interwoven with thermoplastic fibers (2) or fibers to a thermoplastic fiber material fabric (4) as a starting material for the production of fiber composites or workpieces.

Description

technical description

Fiber composites today are dominated by glass fibers and increasingly carbon fibers. The majority of carbon fiber reinforced composites are epoxy matrices. In addition, thermosetting polyester and phenolic matrices with appreciable amounts of carbon fiber reinforced composites are represented here.

In order to ensure good mechanical resistance properties, the maintenance of the calculated fiber orientation is required. The assured automation of fiber laying for product manufacture is an essential goal here.

In the automotive industry, the automated systems for the production of fiber reinforced composite workpieces, such as. B. High pressure RTM process lines from the units: preforming, molding press and finishing. In another process, the carbon prepreg is inserted into the mold and sealed with a silicone film several millimeters thick. Another method uses an automated resin infusion process with rapid polymerization. These procedures have cycle times of about 8 to 15 minutes.

Cycle times are significantly affected by the resins used. The optimization efforts are therefore particularly concerned with increased saturation rates of the preforms for a time-reduced crosslinking time and greatly reduced curing times, which are today at 3 to 5 minutes. Also, the viscosity of the resins is a significant factor because the fiber content in the structural parts is often> 50%, which makes the impregnation difficult.

The cycle times, which require the duration of the impregnation, the polymerization and the curing, are to be designed and placed in the product manufacturing process in such a way that the time-consuming and thus cycle-determining process can be substantially minimized in terms of time. In particular, I define the process of hardening for the secured end geometry generation on the composite workpiece as essential for the overall cycle time of the process chain.

If prepregs or preimpregnated fibers or fiber structures are combined, for example, with thermoplastic interlayers or thermoplastic base and / or support film, then this combination can be earlier taken as a matrix structure from the Endgeometrieform, provided that the thermoplastic is advantageously chosen so that it solidifies sufficiently dimensionally stable earlier , The curing of the prepreg can then conclude process reliable outside of the central molding press. A possible thermoplastic coating in the contact zone to the mold or die dissolves directly after appropriate solidification of the thermoplastic in the contact zone of the advantageous cooled die or the thermoplastic coating is liquid or adhesive heated only to the prepreg and heated not sticking to the die - even if necessary The high surface quality of the thermoplastic overlay to be obtained can enable further economic advantages in mass production.

If the conventional prepregs are replaced by starting material fiber structures, where the fiber structures are crosslinked in thermoplastic material (advantageously, for example, in film form), the production process of fiber composite workpieces can be massively optimized in relation to conventional production. Product-specific blanks of the fiber material can advantageously z. B. from the role autarkic punched for final molding or produced by water jet cutting. These can be used before the final shaping in a suitable material combination as a sandwich structure z. B. hot pre-pressed. Layer structures or sandwich structures can be put together flexibly, even with different layer specifications. In the final shaping of spherical structures, the layer planes or layer planes of the sandwich structure offset each other. The deformation, the dislocation and the final bonding of the layers to each other takes place in one process step!

Starting material fiber structures, where the fiber structures are crosslinked in thermoplastic material (advantageously, for example, in sheet form or strip form) also offer the possibility of hollow bodies such as cylinders, balls, balloons, thin-walled tubes or advantageously convex spherical inlets of z. B: Styrofoam or thin-walled base materials according to the temperature-wrapping force levels completely encapsulating adjacent to enclose.

Composite sandwich structures with fibrous layers and mutually fiber-free layers can have the advantage of a lower fiber content with relatively equivalent and possibly even higher mechanical properties of the component by z. B. a relatively higher fiber content on a larger bending radius. In addition, a tensile stress-loaded fiber-containing layer acts pressure-loading on the underlying z. B. fiber-free layer. Is this fiber-free layer z. As polycarbonate, so this material can act with its high impact resistance in the crash load case strongly dampening on the overlying fiber-containing layer and the load scenario is time-displaced by the multilayer layer layers from the outer to Inner bending radius range of the sandwich structure. This physical situation also applies to superimposed fibrous material, which in Thermoplastträgermaterial, z. As poply carbonate crosslinked is present.

Polycarbonate is a known thermoplastic material which comes into question as inventively advantageously suitable material for corresponding carrier films of fiber materials or as a quasi-prepreg carrier medium. Polycarbonate is plastically well deformable only from a certain temperature. If more complex, spherical geometries are to be generated directly adjacent to each other, the tempered film or film structure to be applied must be plastically deformed (eg via high pressure forming to the die) in accordance with the desired geometry. If this is done according to the invention in 1 production process operation "deformation + bonding or re-bonding", are desired geometries z. B. in devices or by order of the film structure on base parts with desired geometry z. B. by "wrapping + bonding" to produce a two-dimensional and or convex hollow profile advantageous.

If the film structure subsequently z. B. glued in the context of retrofitting, geometrically preformed VSS (eg., Motor vehicle hood reinforcement pad (s) or insert (s)) are to provide as a product or it comes z. B. Method for use, where the films are to be brought locally to the appropriate temperature and created in the deformable state of the component geometry of the base material and there to cool and, if necessary, can be glued directly or glued only after the deformation process to the base fitting , The use of several, thin films as structural components and the possibility of combining different film components or specifications is hereby evaluated according to the invention as being very helpful in order to produce the spherical geometry in a target-oriented, adhesive-bonded manner.

In order for the thermoplastic to be used more effectively as a carrier material or interlayer material or inserted or woven fiber or fiber material, integration into the inductive heatability of the thermoplastic as an option according to the invention is listed as a claim. The integration of ferromagnetic material, eg. B. nanoparticle material in or on the thermoplastic material, causes the thermoplastic is inductively heated. Induction is a proven process in mass production. The option of inductive heatability of the thermoplastics in "field-free use", d. H. not in process plants The series paver offers deployment options that do not exist before this release. As far as I am aware, the polycarbonate (PC) as a thermoplastic starting material is always produced and offered as a transparent material (possibly colored in a later step). This situation makes it possible to explicitly include the option PC material as an inductively heatable starting material along with reduced or no longer given transparency. The high impact strength of the PC material with the possibility of inductive heating for the production of deformable fiber composite material structures according to the invention is expedient for cost advantages in the manufacturing process of corresponding composite material parts and the subsequent deformation of film structures to component actual geometries in the described application in the " free field use ".

Fiber reinforced composites have increasing market shares. Be named according to the invention u. a. Foil composites as a starting material for the production of composite parts, where z. For example, embedded between two thermoplastic films 1 layer (eg.) Carbon fiber fabric, glued, hot-pressed, welded, joined or integratively crosslinked. This simple sandwich structure can be procedurally produced economically automated and this structure can be component or application-specific endanwender related subsequently plastically deform in the manufacturing process or this structure can, for. B. bonded to a tube profile or a corresponding mold automatically wrapped or joined for the cost-effective production of profiles or intermediate products or end products. Thin-layer sandwich structures z. B. of 2 thin thermoplastic films, which were produced cross-linked with 1 thin Faserwerkstofflage as starting material for composites, can also be offered as a roll material. If such materials are used to produce "quasi-prepregs" as an alternative to conventional prepregs (eg epoxy matrices), this does not apply. a. the cooled, necessary, reaction-inhibiting intermediate storage, which is or may be required in conventional prepreg material.

Essential approaches of this application are concerned with making the process technology for the production of workpieces made of fiber-reinforced composite materials more economical and allowing additional constructional degrees of freedom and defining corresponding advantageous starting material such as fabric structures made of combined fiber-thermoplastic material or fiber-thermoplastic film with optionally integrated Ferromagnetic nanoparticles to enable their procedurally targeted inductive heating. Also, the use of different thermoplastics with z. B. different melting temperature in the sandwich structure, if necessary, very helpful to make defined stronger sliding planes for spherical deformation or Erst-Klebe- or Erst- solidification areas. The degree of flexibility for targeted process control in the production of fiber composite workpieces is to be increased considerably over the use of sandwich structures or the indicated starting materials relative to the conventional approaches.

Claims (12)

Fiber material ( 1 ) from z. As glass fibers, carbon fibers as shown in Figure 1 interwoven with thermoplastic threads ( 2 ) or fibers to a thermoplastic fiber material fabric ( 4 ) as starting material for the production of fiber composites or workpieces. Fiber material ( 3 ) from z. B. glass fibers, carbon fibers coated externally with thermoplastic material according to Figure 2 as a starting material or interwoven to a thermoplastic fiber material ( 4 ) as starting material for the production of fiber composites or workpieces. Combinations of fiber material ( 1 ) or ( 3 ) or thermoplastic fiber material ( 4 ) according to Figure 3 with or on carrier film (s) ( 5 ) of thermoplastic material as a starting material for the production of fiber composite materials or workpieces. Construction of Thermoplastic (VSS) Composite Sandwich Structures ( 6 ) in accordance with Figure 3, as a quasi-package of further processing z. As the thermoplastic crosslinking, deformation, curing or re-curing can be supplied. The thermoplastic VSS have the advantage of flexibility in combining different thermoplastic specifications and layer dimensions and arrangements in combination. Thermoplastic cross-linked VSS as fiber material ( 7 ) as shown in Figure 4 as a base material for the thermoplastic production of fiber composites or workpieces. Also, thermoplastic zones ( 8th ) optionally on the VSS, which deliberately not with fiber material from z. B. fiberglass or carbon fiber material are crosslinked. These can be used for further joining operations z. B. as a pronounced slip plane or as a final smooth surface plane for a painting process on the workpiece can be provided by way of example. Thermoplastic cross-linked VSS as fiber material ( 12 ) according to FIG. 5 with crosslinked adhesive structure ( 9 ) or adhesive film ( 10 ) or thermoplastic level ( 11 ) as starting material for the production of fiber composites or workpieces. VSS ( 14 ) in combination according to Fig. 6 with ( 13 ) Prepregs (base = resins or epoxy matrices, polyester, phenolic matrices etc.). The combination possibilities with prepregs are manifold. A major economic advantage may be that thermoplastic components tend to be sufficiently hard or dimensionally stable that a top and bottom thermoplastic layer will not melt and make no contact with the mold, allowing the combination to be removed earlier from the mold. In addition, there is the option of prepreg share z. B. by means of underlay with respect to the load scenarios costly geometric lift with respect to a higher moment of resistance to a larger bending radius and in addition to dampen. Spherical VSS compound ( 16 ) of spherically preformed or final geometric-shaped VSS ( 15 ) according to Figure 7 with prepreg insert (s) ( 13 ). The spherically shaped VSS ( 15 ) can be advantageously included as an insert in the upper and lower die or mold and the inserted prepreg (possibly also spherically preformed) in z. B. enclose shortened cycle time and be further clocked as a composite. Combinations claims 1 to 8, where the defined or some of the thermoplastics used defined particles, ferromagnetic particles or nanoparticles are added, which allow their targeted inductive or partially higher heating. Combinations Claims 1 to 8, where defined or heavily used microwave-absorbing particles or nanoparticles are added to the or some of the thermoplastics used, which allow their targeted or partially higher heating by means of microwave technology. Combinations claims 1 to 10, where as thermoplastic completely, predominantly or partially explicitly polycarbonate or plastics of the polycarbonate family are used. Production of material profiles such as pipes, T-beams, rods, plates, etc. as starting material in combination with claims 1 to 11 for the user-related production of fiber composite workpieces.

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