DE102011106865A1 - Continuous production method for producing fiber-reinforced plastic profiles of any cross-sectional shape using web technology, involves forming a hollow textile structure and preparing the end section of hollow textile structure - Google Patents

Abstract

The method involves forming a hollow textile structure in the form of a hose and preparing the end section of the hollow textile structure by using a shaping element, such that a hollow cross-sectional shape is realizable. The shaping element is used for generating a matrix (2) for preparing a stable fiber-reinforced plastic profile (1). The generated profile is withdrawn conclusively, and the length of generated profile is adjusted for separating the profile. Independent claims are included for the following: (1) a shaping element; (2) an inner mold element of shaping element; (3) a profile transport and trigger mechanism; (4) a profile separator; and (5) a separation method of profile separator.

Description

The present invention describes a continuous manufacturing process for the production of fiber-reinforced plastic profiles of any cross-sectional shape using weaving technique.

Fiber-reinforced plastic profiles are basically known in the patent literature, as well as by products which are available on the market. Distinctions exist with regard to the manufacturing process, as well as the performance characteristics, which have the respective products. In addition to desired properties, the price of the profiles is also relevant. Automated manufacturing processes with a high degree of standardization can fundamentally reduce production costs and are therefore preferred.

US 5132070 For example, describes a process in which a tubular multilayer structure consisting of filament strands and tubular braids as a template for a pultrusion process. A special feature of the method is the representation that the tubular multi-layer structure is subjected to a significant change in cross-section before the actual pultrusion so as to produce profiles of different cross-sectional shape. Another feature of this method is the covering of the profile with a variety of thin metal sheets, which are needed to prevent displacement of the textile layers of the multi-layer structure in the actual pultrusion. A disadvantage of this process, for example, that no profiles can be produced with significant cavity, since neither during the forming process of the cross section, nor during pultrusion, an inner mold is provided, which can ensure a later profile cavity. Furthermore, it is disadvantageous that the use of the textile multilayer structure, the thin metal sheets are necessary to avoid shifting of the textile layers against each other. This is disadvantageous because it significantly complicates the manufacturing process. So not only a mold for the respective order has to be produced customer-specific, but also the sheets have to be newly provided to the exact contours of the profile depending on the order. It should also be noted that US 5132070 describes a process, which starts from the presentation of a tube to form a profile of it. An overall consideration is thus a multi-stage, interrupted process, since the tubular, textile multi-layer structure has to be produced in a first, separate process step, in order to then produce this in the same way US 5132070 subjected to pultrusion process described. The high number of different, sometimes very complex process steps is considered a disadvantage in terms of manufacturing costs.

Textile technology is concerned with US 5132070 a braid, which was supplemented in a multilayer structure with filament strands. DE 4342575 on the other hand describes a weaving process for the production of fiber-reinforced plastic profiles. This is largely a multi-layer fabric, which can be reshaped with the choice of the right binding technique in a subsequent Pultrusionsprozess so that profiles of different cross sections arise. Thus, for example, a double-T carrier can be produced by unfolding both ends during the pultrusion process, when the multilayer fabric has been produced on the loom with the corresponding binding technique. It is assumed that this is also a multi-stage process, whereby DE 4342575 describes the textile manufacturing process on the weaving machine and in a separate, downstream process step, the profile is folded apart to pultrude it in its target cross-section. The disadvantage is similar to US 5132070 the multi-level structure of the overall process, as well as the complexity of the binding technique. However, the biggest disadvantage is that no profiles with significant cavity can be produced, since during the pultrusion process no element is provided which could ensure the internal cavity.

The pultrusion process of filament strands for the production of different profiles is well known. DE 10251518 B4 describes, for example, the production of profiles of different cross section through the pultrusion of filament strands, in this case consisting of renewable raw materials (more precisely, they are fiber strands). Advantage of this method is a great freedom in the shape of the cross section, with hollow sections are possible. Characteristic of fibers and filaments is that they can only absorb forces along their axis, but not in other directions. Since the filament strands at DE 10251518 B4 However, not connected to each other by textile technology, the profile can absorb only small forces in the transverse direction, which is disadvantageous for example in bending and torsional stress. US 5132070 and DE 4342575 Both have described a solution which textile threads in different directions in the profile, so that forces from different directions can be better absorbed than it is a Pultrusionsprodukt of filament strands. Although it is also known that one can add fiber, fleece, or fabric mats on the surface of the profile even with Pultrusionsprodukten filament strands to achieve a transverse reinforcement, but this option is not a satisfactory solution for all cross-sectional shapes and can also technically do not completely replace the missing textile connection between the filament strands.

EP 2055465 A1 also describes a pultrusion product of filament strands. A special feature is the use of carbon nanotubes in the reinforcement matrix. It is therefore a special formulation of a matrix, which refers to the field of application of the EP 2055465 A1 is tuned. Carbon Nano Tubes are currently very expensive to produce. For this reason, it is doubted that this special matrix outside of the target application of the EP 2055465 A1 Use finds. In principle, it is also true here that the filament strands are not connected to one another by textile technology, which leads to the known disadvantage.

Much research has been done in the field of lichen production. For example, a number of patents describe the braiding of a complex preform ( JP 11093039 A ; DE 10 2008 032 344 A1 ), or so-called 3D braiding by means of highly specialized braiding machines ( US 6439096 ). Braids have some advantages as well as significant disadvantages. On the one hand, only a low productivity of the braiding machine can be mentioned, which relates to the production speed, ie the number of turns. On the other hand, this also applies to the limited reel contents of a braiding bobbin, which clearly limits the maximum, defect-free length which can be produced in one piece and, secondly, necessitates regular changing of the braiding bobbins under production conditions, which significantly increases the downtime of the machine. Both factors limit the industrialization of mass products in the area of profiles. Furthermore, especially the braiding of preforms is not a continuous production process. So it can be braided only a preform. Thereafter, the production process is stopped to then cut off the filament strands. In another production step, a new preform must be installed in the braiding machine to make the next part. The discontinuous operation, which is simultaneously associated with a high level of manual labor, is seen from the point of view of manufacturing costs as not advantageous for continuous profiles, especially since the maximum length of such a profile would be limited. In principle, all profiles made of a braid have the decisive disadvantage that the braiding threads are at a certain angle to the production axis (0 °). Typically, this angle is 30 ° to 70 °. However, if a profile is subjected to tension or compression, textile yarns which are not in the profile direction (which corresponds to the 0 ° tensile or compressive direction) will absorb only limited forces because of filaments can only absorb forces in their direction. Clearly, this means that the matrix, which holds the threads in position and has the task to transfer attacking forces on the textile reinforcement, almost alone must absorb the attacking forces, which quickly leads to failure of the component without the potential of the textile reinforcement was even approximately exhausted. This is supported by the behavior of a braid under tensile or compressive loading to change its shape first. For example, a braid under tension before the filaments absorb tensile forces will be deformed by decreasing the bond angle and decreasing the width or diameter of the braid. For this reason, the typical angle of the threads from 30 ° to 70 ° in braids is not considered advantageous for use in profiles which are particularly stressed by tension or compression.

The wrapping of cores is an alternative to braiding and is for example by DE 10326422 A1 described. In addition to the advantage filament strands in different directions to be able to wrap around a core, so as to meet the attacking lines of force on the component, there remains the disadvantage that takes place between the filament strands no textile connection, in particular a crossing of the filament strands, which is already described Disadvantages leads.

Accordingly, the object of the present invention is, firstly, to disclose the most lean, automated and industrialized process possible for producing fiber-reinforced plastic profiles with an adjustable cross-sectional shape. Furthermore, the textile reinforcing material must be characterized in that the individual filament strands are interconnected by textile cross-over. According to the invention, the object is achieved by the method described according to claim 1 and the following subclaims.

• a) Herstellung einer textilen Hohlstruktur (Schlauch) mittels Webtechnik
• b) Verformung der textilen Hohlstruktur durch Formteile in einen gewünschten Zielquerschnitt und gleichzeitige Pultrusion, das heisst Einbringung einer Matrix in die verformte textile Hohlstruktur zur Herstellung eines faserverstärkten Kunststoffes
• c) Abzug des Profils
• d) Ablängung des Profils

The inventive method is characterized by a multi-stage, but uniform, that is uninterrupted process, which is divided into the following process steps, which are integrated in one machine:

• a) Production of a textile hollow structure (tube) by means of weaving technique
• b) Deformation of the textile hollow structure by means of molded parts in a desired target cross-section and simultaneous pultrusion, that is, introduction of a matrix in the deformed textile hollow structure for producing a fiber-reinforced plastic
• c) withdrawal of the profile
• d) cutting the profile

A special feature of the invention is an inner molded part. The inner molded part corresponds to the desired target cross section. When Bandwebprozess elements are already known, which protrude into the finished woven tape. Specifically, the finished woven tape is peeled off over these elements. Such elements are for example edged wires and lancets. The textile hollow structure is thus removed via the inner molded part. In order for the inner molded part to maintain its position, it is held in place by a wire from the direction of the warp feed, as is known from edged wires and lancets. An inner molding in this embodiment is only feasible when the textile is made. Subsequent to introduce an inner molding in a textile hollow structure can only by consuming constructions, such as in DE 69112810 T2 described, done. The advantage of implementing the target cross-section through an inner molded part directly during the weaving process on the weaving machine is, first, that this variant described in contrast to the solution in DE 691128101 T2 , represents a structurally very simple variant and secondly the design of an uninterrupted production process of the profile, only with the presentation of filament strands guaranteed.

The inner molding is complemented by an outer molding. The outer molding has several functions. On the one hand, extremely complex cross-sections can be realized with the aid of an outer molded part, which would not be possible without the outer molded part. Furthermore, the molding process by the multipart molding at the same time represents the process step "pultrusion". For this purpose, either the moldings individually, or both moldings are heated together and targeted to a specific temperature. The temperature can be used to introduce a reinforcing matrix into the textile reinforcing structure.

The gain matrix can be provided in different ways. First, a thermoplastic material can be supplied as a thread material between the reinforcing fibers on the loom and thus the pultrusion head, which simultaneously represents the shaping. The prerequisite is that the melting point of the reinforcing matrix is well below the melting point of the textile reinforcing material. When using, for example, polyethylene terephthalate (melting point: about 260 ° C) as a reinforcing material, eg polypropylene (melting point: about 160 ° C) can be selected as a meltable matrix in the original form as a textile thread. As an alternative, the market already offers filament strands which are precisely tailored to this purpose and will provide reinforcing material in the correct mixing ratio in a filament strand together with the material which will form the matrix. One such product is, for example, Twintex ^® Owens Corning. Secondly, it is possible to introduce a reinforcing matrix from the outside through injection nozzles inside the pultrusion head (outer molding). This material may also be a thermoset material which has no melting point and chemically cures during the pultrusion process.

After pultruding, the profile is finished from a technical point of view. The trigger must ensure that the profile is transported without slippage. Since the profile is not compressible, the trigger must take into account the respective cross-sectional shape. On the one hand, this is done with specialized roller pairs, which is very time-consuming. Another solution would be a gripping arm which grips and pulls the profile. Although no endlessly long profiles can be produced, on the other hand this is not necessary since rigid profiles always have a limited maximum length.

In a final process step, the profile must be separated to length. The nature of the separation process determines whether the overall process is continuous or discontinuous. Since this profile is a rigid or solid structure, it can not be separated with a simple paper cut. Depending on the profile size and cross section, as well as the choice of materials, the following methods of separation are possible: sawing; Laser cutting; mechanical and thermal cutting, as well as water jet cutting. Preference is given to sawing. All proposed processes take a certain time, so that either the profile must not be moved during the separation process, or the separator moves uniformly during the separation process with the profile. The aim is that no relative movement between separator and profile takes place. However, discontinuous operation can be completely automated, eliminating the need for manual intervention during the separation process.

If the above-described variant of a gripping arm is executed as a trigger, a discontinuous working also results here, which can be automated as well as the separation process. Preferably, the separation of the profile with the discontinuous profile deduction by a gripper arm, executed synchronized in time.

Example 1:

A first embodiment is intended to describe the method with reference to a round hollow profile. As a manufacturing method of the textile fiber composite tape weaving technique is used in this case. As a template serve two types of Filament strands. On the one hand, polyethylene terephthalate ( : 1 ), which forms the reinforcing fiber in the fiber-reinforced plastic profile. On the other hand, a second Filamentstrangschar consisting of polypropylene ( : 2 ) the later matrix of fiber reinforced plastic. The filament strands of both materials alternate with each other and form the so-called warp threads. In addition, a weft thread ( : 3 ), also consisting of polyethylene terephthalate fed to the loom. This weft is also part of the reinforcing fibers within the fiber reinforced plastic. To produce a tube, the bonding technique known to those skilled in the art is used. A ribbon fabric made on modern needle-and-ribbon webbing machines has a typical crocheted edge. In this special case, this edge is formed by feeding to a person skilled in the art under the term auxiliary thread known additional thread, which also consists of polyethylene terephthalate. The number and the specific weight of the filament strands of both materials are chosen so that the fiber-reinforced plastic has a content of 65% of the filaments consisting of polyethylene terephthalate. The bandwidth corresponds to half the circumference of the desired round hollow profile. It should be expressly noted that all materials that make up the fiber-reinforced plastic are supplied as textile filament strands in the form of weft, warp and edged threads.

Since the target cross-section is a round hollow profile, the inner mold element ( : 4 ) also has a round cross section whose diameter corresponds to the inner diameter of the round hollow profile. The inner form element is replaced by a wire ( : 5 ), which is guided with the warp threads through the reed and the complete shaft package and which is mounted on the Webbaumknecht held. This procedure is known to the person skilled in the art from the use of square wires. Parallel to this wire, a cable is guided, which supplies a heating cartridge within the mold element with electrical energy to regulate this to a certain temperature.

In addition to the inner mold element, an outer mold element ( : 6 ), which serves to melt the material for the Versträrkungsmatrix, as well as to distribute this material evenly. The inner diameter of the outer mold element corresponds to the outer diameter of the desired round hollow profile. In its mode of operation and thus also in its construction, the outer mold element corresponds to a pultrusion head, which is known to the person skilled in the art through numerous publications.

The withdrawal of the round hollow profile is carried out by a pair of rollers ( : 7 ), wherein the take-off rolls are adapted to the geometric shape of the round hollow profile. The speed of the deduction in relation to the number of revolutions of the machine determines the web technical parameters, such as weft density and basis weight, as well as the parameters within the pultrusion head, which are decisive for the melting, distribution and cooling of the matrix.

The lengthening is done by a legend, for example in a discontinuous working process. This means that the entire production process is stopped during the sawing process. Stop, cut and resume production are automated.

The round hollow profile described can be used, for example, in apparatus and plant construction and is particularly helpful when an optimized ratio between component weight and insert properties (eg tensile strength / compressive strength) is required.

Example 2:

• – Auswahl des Verstärkungsmateriales: es kommen neben dem erwähnten Polyethylenterephthalat auch andere Materialien zum Einsatz, wie diverse Polyamide und Aramide, Glas- und Kohlefaser, Viskose, Polyetheretherketon, sowie Naturfasern (insbesondere Baumwolle, Sisal, Kokos, Wolle)
• – Auswahl des Materiales für die Verstärkungsmatrix: neben thermoplastischen Materialien mit geringem Schmelzpunkt wie Polypropylen, gibt es auch vernetzende Materialien, wie es beispielsweise Epoxidharze, Polyesterharze, Acrylharze und Phenolharze sind.
• – Dem Fachmann sind vorteilhafte Materialkombinationen zwischen Verstärkungsfaser und Matrix hinreichend bekannt, weshalb auf die unterschiedlichen Kombinationen hier nicht genauer eingegangen wird.
• – Ein Einbringen einer Matrix von aussen, das heisst nicht durch die Zuführung von textilen Filamentsträngen erfolgt unter Druck am Pultrusionskopf, also dem äusseren Formelement durch dort installierte Düsen.
• – Alle denkbaren und üblichen Profilquerschnitte können realisiert werden, wobei alle Querschnittsformen als Hohlquerschnitt ausgeführt werden (siehe ).
• – Die Wandstärke des Profils wird durch die Anzahl der Filamentstränge, deren Verteilung (Dichte), sowie die Bindungstechnik bestimmt. Es ist beispielsweise denkbar durch die Konstruktion eines Vierlagengewebes (wobei jeweils 2 benachbarte Lagen durch textile Fäden miteinander verbunden sind und beide Lagenpakete die textile Schlauchstruktur bilden, da die Lagenpakete nur an ihren beiden Kanten miteinander verbunden sind) die Wandstärke gezielt einzustellen und auf die jeweilige Anwendung zu optimieren.

Based on Example 1, a second application example is formulated to illustrate the flexibility of the method. The changed parameters compared to the previous example are summarized as follows:

• Selection of the reinforcing material: besides the polyethylene terephthalate mentioned, other materials are also used, such as various polyamides and aramids, glass and carbon fibers, viscose, polyether ether ketone, and natural fibers (in particular cotton, sisal, coconut, wool)
• Selection of reinforcing matrix material: in addition to low melting point thermoplastic materials such as polypropylene, there are also crosslinking materials such as epoxy resins, polyester resins, acrylic resins and phenolic resins.
• The skilled worker is well aware of advantageous combinations of materials between the reinforcing fiber and the matrix, which is why the different combinations will not be discussed in more detail here.
• - An introduction of a matrix from the outside, that is not by the supply of textile filament strands takes place under pressure at Pultrusionskopf, so the outer mold element through there installed nozzles.
• - All conceivable and usual profile cross-sections can be realized, with all cross-sectional shapes are designed as a hollow cross-section (see ).
• - The wall thickness of the profile is determined by the number of filament strands, their distribution (density), as well as the binding technique. It is conceivable, for example, by the construction of a four-ply fabric (two adjacent layers are connected to each other by textile threads and both ply packages form the textile tube structure, since the ply packages are connected only at their two edges) adjust the wall thickness targeted and to the particular application to optimize.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5132070 [0003, 0003, 0003, 0004, 0004, 0005]
• DE 4342575 [0004, 0004, 0005]
• DE 10251518 B4 [0005, 0005]
• EP 2055465 A1 [0006, 0006, 0006]
• JP 11093039 A [0007]
• DE 102008032344 A1 [0007]
• US 6439096 [0007]
• DE 10326422 A1 [0008]
• DE 69112810 T2 [0011]
• DE 691128101 T2 [0011]

Claims (11)

Claimed is a fiber-reinforced plastic profile arbitrary hollow cross-section, and a method for its preparation, characterized in that in a first step, a hollow, textile structure (similar to a hose) is produced, wherein the end cross-section is produced in a second process step by a shaping element, that Any possible hollow cross-sectional shape can be realized, wherein the shaping element can simultaneously serve to produce the matrix and thus leads to stable profile generation, and a subsequent third process step, which subtracts the profile generated, to finally in a fourth process step to any adjustable length separate. The production of the hollow textile structure according to claim 1 is carried out by weaving, wherein the weaving processes are particularly suitable on rapier, air and projectile weaving, as well as shooter, shuttle and Nadelbandwebtechnik have proven to be particularly advantageous. The method according to claim 1 is characterized in particular in that it is a continuous process, so that the individually described process steps of claim 1 take place on a unitary machine and the result represents an end product in the form of a profile. As a template for the manufacturing process textile yarns apply and the result is a finished profile. A shaping element according to claim 1 consists of a positive mold as an inner part with an additional, suitable negative mold as the outer part, on the one hand to realize complex cross-sections, and on the other hand to introduce a reinforcing matrix in the textile hollow structure. The cross sections of the molds correspond to the target cross section of the final profile. The inner molding of the forming element is held in the weaving process from the direction of the textile yarn feed (warp supply) by a wire or similar construction so that the hollow textile structure described in the previous claims on the inner mold part can be deducted. The shaping element according to claims 1 and 3 to 5 is characterized in that the inner and / or outer part can be heated and regulated to a certain temperature. This temperature corresponds to either the glass transition temperature (as well as up to 50% above the glass transition temperature, but preferably about 10-20% above the glass transition temperature) of the textile material used to thermally stabilize the textile surface and thereby give it its intended shape, or one Temperature which corresponds to the melting temperature (and up to 50% above the melting temperature, but preferably about 10-20% above the melting temperature) of a textile, thermoplastic material to melt this and to use as a matrix within the fiber-reinforced plastic. A shaping element according to claims 1 and 3 to 6 can furthermore be characterized in that an external matrix can be introduced into the hollow textile structure with the aid of injectors in the negative outer mold in such a way that a fiber-reinforced plastic is produced. As materials for a fiber-reinforced plastic profile and the described method according to the previous claims, in principle, the materials and material combinations established in textile technology and plastics technology can be used. The following materials are particularly suitable: a. For the reinforcing fibers: natural fibers (especially cotton, sisal, coconut, wool); Synthetic fibers and filaments (in particular polyesters such as polyethylene terephthalate, but also other polyesters, polyamides such as polyamide 6, polyamide 6.6, polyamide 4.6, but also other polyamides, polyimides, polyetheretherketone, viscose), as well as high-tech materials such as glass, aramides (Kevlar ^® , Twaron ^® and Nomex ^® ), carbon fiber and other b. For the matrix: thermoplastic materials such as polypropylene, or crosslinking materials such as epoxy resins, polyester resins, acrylic resins, phenolic resins and others. The profile transport and withdrawal device according to claim 1 is characterized in that it takes into account the respective cross-section of the produced profile and can take place as a continuous take-off device, for example in the form of a pair of rollers, or as a discontinuous removal device, for example in the form of a withdrawing gripping arm , The profile separation device after the profile deduction is either characterized in that this profile separation device is designed as a stand-alone separating device, which must lead to a provisional production stop in a rigid profile. The process flow can be automated so that production stop, profile separation and production start can be carried out automatically. A second possibility is a follower profile separation device. In a running profile separation device no production standstill must occur, but the profile separation device must follow the profile transport with precise speed as long as the separation process stops. After profiling has the Profile separator moved back to its original position. From the times of the travel distances and the production speed results in a minimum profile length, which can not be fallen below. As a separation method for a profile separating device according to claim 10, depending on the materials used, which have been processed in the fiber-reinforced plastic profile, as well as the profile dimension following methods in question: mechanical cutting, sawing, thermal cutting, laser cutting, water jet cutting.

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