Thermoplastic fiber, hybrid yarn, fiber perform and method for producing fiber performs for fiber composite components, in particular high performance fiber composite component, using the same, fiber composite component and method for producing fiber composite components, in particular high performance fiber composite components
20170246814 · 2017-08-31
Assignee
Inventors
Cpc classification
B29C35/0805
PERFORMING OPERATIONS; TRANSPORTING
B29B11/16
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/2913
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
B29C70/04
PERFORMING OPERATIONS; TRANSPORTING
Y10T442/699
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
D02G3/447
TEXTILES; PAPER
Y10T428/2929
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
D02G3/402
TEXTILES; PAPER
B29C70/30
PERFORMING OPERATIONS; TRANSPORTING
Y10T428/249921
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T442/30
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T428/2927
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
Y10T442/40
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
International classification
B29C70/34
PERFORMING OPERATIONS; TRANSPORTING
B29C70/24
PERFORMING OPERATIONS; TRANSPORTING
B29C35/08
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A method for producing a fiber preform or semi-finished textile product comprises providing a fiber preform or semi-finished textile product comprising at least one thermoplastic fiber. The thermoplastic fiber has a core constructed of a first material, a shell constructed of a second material positioned to surround the core, and magnetic particles that are one of mainly arranged in the shell, almost exclusively arranged in the shell, and exclusively arranged in the shell. Continually adding the fiber preform or semi-finished textile product with simultaneous heating thereof in continuous passing through or passing by a magnetic induction heating device or the same by way of a relative movement. Fixing the fiber preform or semi-finished textile product by allowing the fiber preform or semi-finished textile product to rigidify.
Claims
1. A method for producing a fiber preform or semi-finished textile product comprising: providing a fiber preform or semi-finished textile product comprising at least one thermoplastic fiber, the thermoplastic fiber having a core constructed of a first material, a shell constructed of a second material positioned to surround the core, and magnetic particles that are one of mainly arranged in the shell, almost exclusively arranged in the shell, and exclusively arranged in the shell; continually adding the fiber preform or semi-finished textile product with simultaneous heating thereof in continuous passing through or passing by a magnetic induction heating device or the same by way of a relative movement; and fixing the fiber preform or semi-finished textile product by allowing the fiber preform or semi-finished textile product to rigidify.
2. The method of claim 1 wherein the fiber preform or semi-finished textile product comprises a plurality of reinforcement fibers.
3. The method of claim 1 wherein the first material and the second material are identical.
4. The method of claim 1 wherein the first material and the second material are different.
5. The method of claim 1 wherein the fiber is unstretched.
6. The method of claim 1 wherein the fiber is stretched.
7. The method of claim 1 wherein the core has a diameter in the range of about 5 μm to about 60 μm.
8. The method of claim 1 wherein the core has a diameter in the range of 20 μm to 30 μm.
9. The method of claim 1 wherein the heat-up performance of the fiber preform or semi-finished textile product is controlled by way of a concentration of the magnetic particles, the thickness of the shell, or both.
10. The method of claim 1 wherein the shell has a thickness in a range of about 0.1 μm to about 20 μm.
11. The method of claim 1 wherein a concentration of the magnetic particles in the shell is in a range of about 10 weight percent to about 50 weight percent.
12. The method of claim 1 wherein the fiber preform or semi-finished textile product is suited for the thermal fixing of fiber preforms
13. The method of claim 1 wherein the fiber preform or semi-finished textile product is suited for the thermal fixing of fiber preforms for, endless fiber reinforced, fiber composite components, and in particular high performance fiber composite components.
14. The method of claim 1 wherein the thermoplastic fibers include at least one of polyetherketone, polyetheretherketone (PEEK), polyphenylene sulphide (PPS), polyimide, particular polyetherimide (PEI), polysulfone (PSU), polyethersulfone (PES), polyamide (PA) and polyvinylidine fluoride (PVDF).
15. The method of claim 1 wherein the carrying layer is two-dimensional.
16. The method of claim 1 wherein the fiber preforms are for endless fiber reinforced, fiber composite components.
17. The method of claim 1 wherein the fiber preforms are for high performance fiber composite components.
18. The method of claim 1 further comprising, after heating and before fixing the fiber preform or semi-finished textile product, lay-up of the fiber preform or semi-finished textile product in any path curve on a carrying layer.
19. The method of claim 1 further comprising, after heating and before fixing the fiber preform or semi-finished textile product, lay-up of the fiber preform or semi-finished textile product in any path curve on a carrying layer, wherein the fiber preform or semi-finished textile product is pressed during or after lay-up on the carrying layer.
20. The method claim 1 in which the magnetic particles comprise ferromagnetic particles, ferrimagnetic particles, or both.
21. A method for producing fiber composite components comprising: providing the continuous addition of the fiber preform or semi-finished textile product having a plurality of reinforcement fibers, a plurality of thermoplastic fibers, and at least some of the plurality of thermoplastic fibers including at least one of proportionately ferromagnetic particles and proportionately ferrimagnetic particles; simultaneous heating thereof in continuous passing through or passing by a magnetic induction heating device or the same; fixing of the fiber preform or semi-finished textile product by allowing it to rigidify; and thermoforming of the fiber preform produced for the production of a three-dimensionally formed fiber composite component.
22. The method of claim 21 wherein the components are endless fiber reinforced, fiber composite components.
23. The method of claim 21 wherein the components are high performance composite components.
24. The method of claim 21 wherein the carrying layer is two-dimensional.
25. The method of claim 21 further comprising, after heating and before fixing the fiber preform or semi-finished textile product, lay-up of the fiber preform or semi-finished textile product in any path curve on a carrying layer.
26. The method of claim 21 further comprising, after heating and before fixing the fiber preform or semi-finished textile product, lay-up of the fiber preform or semi-finished textile product in any path curve on a carrying layer, wherein the fiber preform or semi-finished textile product is pressed during or after lay-up on the carrying layer.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Further features and advantages of the invention follow from the attached claims and the following description, in which a plurality of exemplary embodiments are individually explained by reference to the schematic drawings, in which:
[0035]
[0036]
[0037]
[0038]
[0039]
[0040]
[0041]
[0042]
[0043]
[0044]
[0045]
[0046]
DETAILED DESCRIPTION
[0047]
[0048] The thermoplastic fiber 10 shown in
[0049]
[0050]
[0051]
[0052] The hybrid yarn shown in
[0053]
[0054] In one contemplated embodiment of the invention, the hybrid yarns 18 are produced from functionalized, that is to say shell-selectively inductively meltable shell 14—core 12 thermoplastics 10, preferably polyetheretherketone (PEEK) and reinforcement fibers 20, preferably carbon fibers. In order to produce a fiber preform by means of the previously described modified TFP method, the shell 14 of the thermoplastic fibers 10, modified with ferromagnetic particles 16, preferably iron oxides such as MagSilica®, is inductively activated and melts. During the pre-fixing the melted shell component hereby acts as a binding agent. In contrast with the normal TFP method with a stitching head, the use of stitching threads can hereby be omitted, which otherwise leads to filament damage, fiber undulations and resin nests. Furthermore, with this method there is no limitation of the number of layers as the layers are stuck one on top of the other and do not need to be stitched.
[0055] The high flexibility of the hybrid yarn further facilitates very small lay-up radii and is thus superior to the tow placement method with complex component geometries.
[0056] On the basis of the preliminary investigations for the shell-core distribution within the bi-component thermoplastic fibers, a shell volume portion of 10% by volume could be technically realized. In terms of large scale, lower shell portions in the region of 1% can be achieved so that the required portion of ferromagnetic particles in the component can lie below 1%.
[0057] A first example of a process chain for manufacturing endless fiber reinforced fiber composite components out of hybrid yarn will now be described. It can be divided into the following sub-steps:
Hybrid Yarn Production
[0058] In a bi-component melting-spinning process the same thermoplastic is used for the shell and also for the core of the thermoplastic fiber. The shell is hereby modified with ferromagnetic particles. By means of for example the commingling method, modified air texturing machines or friction spinning, the shell-core thermoplastic fibers and the reinforcement fibers can be homogeneously mixed to a hybrid yarn in a ratio which corresponds to the later fiber volume content of the fiber composite component. The fiber finenesses are orientated to the hybrid yarn homogeneity and the resulting fiber composite component homogeneity.
Preforming Tow Placement
[0059] A lay-up head (not shown) provided with magnetic induction heating technology thermally activates the shell of the thermoplastic fibers via the ferromagnetic particles so that the hybrid yarn can be laid up and fixed in accordance with force flow on a 2D development of a component end contour (carrying layer). Undulations of the reinforcement fibers and limitations in the number of layers can be avoided in this method in comparison with normal TFP technology.
[0060] The lay-up head can be installed both on a robotic arm and on a portal system. It is also possible with the described lay-up technology to lay up different hybrid yarns on any two-dimensional paths. The fiber architecture can thus be optimally adapted to the later fiber composite component load in order to thus fully exploit the material potential. Through lay-up on the end contour all the material used is used in the fiber composite component. Through this efficient use of material, in spite of expensive starting materials, high performance fiber composite components can be produced at favorable prices. This technology of a lay-up head can also be transferred to other methods, such as form example the winding method.
Consolidation
[0061] The three-dimensional forming and consolidation can subsequently take place in a thermoforming process.
[0062] The installation technology can be adapted well. This offers freedom in the component geometry which can be produced. In addition, the method is suitable—due to the low refitting resources—also for small scale production. The semi-finished products are product-non-specific and can thus be used for a very broad spectrum of applications.
[0063] The good adaptability of the installation technology to different geometries also opens up opportunities for economic production of variant-rich series in mechanical engineering and in orthopedic technology. The fiber composite components are constructed from simple and specific semi-finished products and have a low waste. They are end contour precise, can be thermally joined to injection molded parts and do not require any corrosion protection.
[0064] An overview of another example of a process chain is given in
[0065] Preforms are produced on a TFP facility (Tajima TMLH-G108 Type D3-1) with a modified stitching head on a PVAL foil (Solublon, Typ KA 30 micron) as substrate.
[0066] Fiber lay-up with TFP-technology allows manufacturing of textile preforms with several layers in one step. Each hybrid yarn (plied or commingled) is fixed with an upper and a lower thread by zigzag stitches. Except for the substrate, a one layer preform is nearly symmetrical. Additional TFP-layers demand further upper and lower stitching thread, so that TFP-preforms have on the lower side a concentration of stitching thread. Furthermore, the lower layers are much more transfixed than the upper ones. To avoid matrix agglomerations (build-up of lower stitching thread) and filament damage the matrix will be modified with ferromagnetic particles (MagSilica® Evonik), in which a single particle has a nano scale. First estimations suggest that a nanoparticle concentration less than 1 weight percent, corresponding to the total CFRTP-part weight, will be enough to reach an economical preform production process.
[0067] The subsequent drapery and consolidation takes place in a Rucks KV 214 press. Here the melted stitching thread and the thermoplastic multifilament results in the matrix fraction. Basic parameters for the consolidation process are given by Schappe Techniques (“N.N.: ENSEMBLE Fiches BDEF GB Issue 03-2009, Schappe Techniques, 2009”) for a commercial commingled yarn (Nm 3.2 TPFL CARBON/PPS, Schappe Techniques). Moulding and demoulding temperature was 200° C. and consolidation temperature was 315° C. The realized heat-up and cooling-down speed was limited by the equipment to 10 K/min. Before testing a past-conditioning was made at 230° C.
[0068] Closing the material performance was characterized by polished cut image analysis and mechanical testing according to DIN EN 2561 (test apparatus Zwick/Roell Z250).
Hybrid-Preforming
[0069] Different geometries of hybrid preforms have been realized. The geometrical flexibility of the TFP-Process is demonstrated in the shape of a hatrack bracket (
[0070] Standard textiles like woven or knitted fabrics would have for this geometry more than 50% cutting scrap and a much lower performance from the mechanical point of view. The use of dry carbon fiber multifilament yarns enabled us fiber lay-up on small radii down to 10 mm without any visible filament undulations causes by the fiber path.
[0071] Because of the complex stress fields of load application areas, a combination of the consolidated CFRTP-part with injection die molding is useful for this part. Finite element analyses shows that this combination enhanced the ultimate load by about 30% while adding 15% weight of CFRTP (“Shi, Y.: Beitrag zur Prozesskettenentwicklung von endlosfaserverstärkten Thermoplastbauteilen für Groβserien, Diploma Thesis, Universitat Bremen, 22.07.2009 Bremen”).
[0072] The preform in the photo in
Consolidation
[0073] The internal laminate-structure of hybrid preforms made from commingled yarns as well as the ones which were created in side-by-side technology is regular. Polished cut images of laminates made from commingled yarns from Schappe Techniques are characterized by resin rich areas (
[0074] In both cases the laminates are fully impregnated and no phase separation is visible. The stitching thread is completely melted and has become a part of the matrix. The realized fiber volume content is about 45%.
Mechanical Properties
[0075]
[0076] Actually, the realized mechanical properties are higher for the side-by-side laminate than for the commercial ones due to the more stretched fibers without woven undulations. For the commingled yarn especially the tensile modulus is lower due to fiber breakages caused by the commingling process.
[0077] Depending on later applications the used hybrid yarn can consist of different types of reinforcing fibers (carbon, glass, basalt, aramid) and any type of thermoplastic resin. Preferable are high performance thermoplastic resins like Vestskeep 2000 G (PEEK, Evonik). The hybrid yarn build-up can be side-by-side, commingled or wrapped, in which the reinforcing fiber volume content can be designed regarding the later application (e.g. aircraft industry 50%).
[0078] For the preliminary induction analyses modified matrix filaments are produced with a spinning tester in vertical direction (SDL Atlas—Laboratory Mixing Extruder). The corresponding PEEK compounds were delivered by Evonik with a MagSilica® 50-85 (content of 10 weight-%) and MagSilica® VP300 (content of 15, 20 and 30 weight-%). MagSilica VP300 is particularly advantageous for heating. The spun filaments are characterized by polished cut image analysis, scanning electron microscopy (SEM) and mechanical single fiber testing according to DIN EN ISO 5079: 1996 (Dia-Ston equipment). Afterwards the heat up behavior is analyzed using a Himmelwerk Sinus 52 ring coil (inner diameter: 6 mm, length: 22 mm, power: 6.0 kW; frequency: 1.8 MHz) and contactless temperature measurement.
Filament Spinning
[0079] The effect of Vestakeep 2000 G modification through MagSilica® 300VP is shown in
[0080] The filament spinning takes place at 360° C. In contrast to pure PEEK the spinning temperature has to be lowered for a good fiber formation due to the lower viscosity. The lower spinning temperature results in higher melt stiffness but otherwise the nanoparticles induce melt fracture. However, spin drafts up to 100 could be reached in the laboratory scale. In comparison to typical spin drafts for melt spun fibers (F. Fourné, “Synthetische Fasern—Herstellung, Maschinen und Apparate, Eigenschaften”; Handbuch für Anlagenplanung, Maschinenkonstruktion und Betrieb; Hanser Verlag, München/Wien, 1995, Chapt. 3, p. 182″) this is promising regarding the industrial implementation.
[0081] If the higher spinning speeds in industrial scale cause unexpected filament breakages the core/shell filament build up could be used, whereas a non-modified pure PEEK core acts as a spinning carrier (
[0082] The core/shell structure generates also more advantages for which reason this filament structure is preferred.
[0083] 1. During the bonding the unmodified core stabilized the melted shell, whereby faster perform production rates can be used.
[0084] 2. To reach high heating rates the MagSilica® content of the shell can be chosen very high, whereas the unmodified core makes sure that the overall concentration is still low. The feasibility through the spinning carrier effect is ensured.
[0085] 3. Through changing the thickness the adhesion strength can be controlled. Normal industrial shell fraction can be from 1-99 vol.-%.
[0086] 4. Depending on the application different materials can be used for the core and shell component. It is not necessary that core and shell have the same polymeric feedstock.
[0087] 5. Overall this technology can generate CFRP-parts with a very low amount of nanoparticles:
[0088] 30 wt-% MagSilica® in the shell corresponds to 11 vol-%. With 10% shell fraction and 50% modified binding matrix filaments this leads to 0.3 vol-% nanoparticles for an aircraft component with a fiber volume content of 50%.
[0089] 1. During the bonding the unmodified core stabilized the melted shell, whereby faster perform production rates can be used.
[0090] 2. To reach high heating rates the MagSilica® content of the shell can be chosen very high, whereas the unmodified core makes sure that the overall concentration is still low. The feasibility through the spinning carrier effect is ensured.
[0091] 3. Through changing the thickness the adhesion strength can be controlled. Normal industrial shell fraction can be from 1-99 vol.-%.
[0092] 4. Depending on the application different materials can be used for the core and shell component. It is not necessary that core and shell have the same polymeric feedstock.
[0093] 5. Overall this technology can generate CFRP-parts with a very low amount of nanoparticles:
[0094] 30 wt-% MagSilica® in the shell corresponds to 11 vol-%. With 10% shell fraction and 50% modified binding matrix filaments this leads to 0.3 vol-% nanoparticles for an aircraft component with a fiber volume content of 50%.
Filament Properties
[0095] With 90-100 MPa for the tensile strength, complete nano-modified PEEK filaments are comparable to neat PEEK according to DIN EN ISO 527-2. These mechanical properties (for unstretched filaments) are sufficient for a safe handling during the modified TFP process. Depending on the process parameters filament diameters can be realized between 10 and 100 μm.
[0096] For stretched filaments the tensile strength is preferably in the range of about 300 to about 1000 MPa.
Heat Up Behavior
[0097] Heating up experiments showed that with MagSilica® VP300 higher heating rates can be generated in comparison to MagSilica® 50-85. Therefore, the following results concentrate on VP300.
[0098] A big advantage of using filament is the possibility of using high performance induction coils. These coils are very compact with inner diameters less than 10 mm. The influence of the used equipment can be seen in
[0099] Furthermore, filaments, modified with 30 wt.-% MagSilica VP300, reach the melting region of PEEK within 0.7 seconds (about 510 K/s). Latest induction tests with MagSilica HS even shown that heating rates of 720 K/s to reach PEEK melting temperature are possible, whereby the use of these technologies for nearly all thermoplastic resins is verified.
[0100] It will be appreciated that an appropriate process chain is not limited to the two examples described herein. For example, the number and kind of steps as well as the parameters of the steps could be modified.
[0101] The process chains set out and the possible products have at least in particular embodiments the following advantages individually or in combination:
[0102] The new fixing type of the hybrid yarn facilitates, in comparison with TFP technology, the damage-free lay-up of reinforcement fibers also on paths with low radii of curvature (lay-up radii) and for thick preforms.
[0103] In comparison with existing tow placement systems, clearly smaller in-plane lay-up radii without fiber waviness can be realized.
[0104] Apart from the very small proportion of ferromagnetic and/or ferrimagnetic particles, no further auxiliary agents such as low melting thermoplastic binding agents are required, which can lead according to the field of use of the material to reducing hot-wet properties.
[0105] Material properties can be optimally adapted to the component loads via the tailor-made orientation of the reinforcement fibers.
[0106] Through the high degree of automation of the process chain, a customer-orientated production in countries with a comparatively high wage level is possible. Process security is guaranteed.
[0107] With the production of the preforms on end contour by means of the tow placement method the cutting of the flat textile product is avoided. Besides costs for the cutting devices and staff, the otherwise usual waste is clearly reduced. Quality losses which are otherwise caused in the form of fiber undulations in the cutting process and the handling of flexible textiles do not have to be considered either.
[0108] The sufficiently high rigidity of the fiber preform facilitates storage and safe transportation. The production of the preforms can take place in the textile supplier industry. The workload of component-unspecific tow placement systems is thus ensured and the respective expert knowledge of the different branches of the economy is used.
[0109] The short cycle times allow the realization of lightweight construction concepts for a broad field of application. The new products are thereby characterized by low weight, increased performance capacity and reduced energy consumption in operation.
[0110] The new fixing type of the hybrid yarn facilitates, in comparison with TFP technology, the damage-free lay-up of reinforcement fibers also on paths with low radii of curvature (lay-up radii) and for thick preforms.
[0111] In comparison with existing tow placement systems, clearly smaller in-plane lay-up radii without fiber waviness can be realized.
[0112] Apart from the very small proportion of ferromagnetic and/or ferrimagnetic particles, no further auxiliary agents such as low melting thermoplastic binding agents are required, which can lead according to the field of use of the material to reducing hot-wet properties.
[0113] Material properties can be optimally adapted to the component loads via the tailor-made orientation of the reinforcement fibers.
[0114] Through the high degree of automation of the process chain, a customer-orientated production in countries with a comparatively high wage level is possible. Process security is guaranteed.
[0115] With the production of the preforms on end contour by means of the tow placement method the cutting of the flat textile product is avoided. Besides costs for the cutting devices and staff, the otherwise usual waste is clearly reduced. Quality losses which are otherwise caused in the form of fiber undulations in the cutting process and the handling of flexible textiles do not have to be considered either.
[0116] The sufficiently high rigidity of the fiber preform facilitates storage and safe transportation. The production of the preforms can take place in the textile supplier industry. The workload of component-unspecific tow placement systems is thus ensured and the respective expert knowledge of the different branches of the economy is used.
[0117] The short cycle times allow the realization of lightweight construction concepts for a broad field of application. The new products are thereby characterized by low weight, increased performance capacity and reduced energy consumption in operation.
[0118] The features of the invention disclosed in the present description, in the drawings, and in the claims, can be essential to implementing the invention in its various embodiments both individually and in any combinations. It is contemplated that several modifications can be made to the embodiments described herein within the spirit and scope of the invention without departing from the anticipated scope of the claims.