IRRADIATION DEVICE FOR FIBER COMPOSITE MATERIAL
A device is provided having a holder region including a first holder for a first thread and at least one further holder for at least one further thread, at least one contact area for contacting the first thread and the at least one further thread. At least one radiation source is provided between the holder region and the contact area.
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This application is a Section 371 of International Application No. PCT/EP2012/001267, filed Mar. 22, 2013, which was published in the German language on Oct. 26, 2012, under International Publication No. WO 2012/143076 A1 and the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTIONThe invention relates, in general, to a device for producing a composite, a method for producing a composite, and also a composite obtainable according to this method. In particular, the invention is used for the optimized treatment of threads by irradiation during the composite production process.
From the prior art, devices are known for processing fibers or threads for fiber composite materials, in which initially at least two threads or fibers are interwoven or interconnected in some other way and then subjected to a heating process, in order to obtain a sufficient connection or fusing of the threads. This is described, for example, in U.S. Pat. No. 4,800,113 and is known for various applications.
From European patent application publication EP 0 717 133 A1 and U.S. Pat. No. 5,688,594 it is known that different kinds of fibers or fabrics can be processed with each other, in order to allow a permanently deformable textile material to be prepared. Here, a structure is also woven from one or more threads, and this structure is then connected to other structures by the effect of heat, in order to be able to take advantage of various properties of the individual materials in the composite material.
In German published patent application DE 10 2007 037 316 A1 it is described how thermoplastic molded bodies are produced on the basis of thermoplastic materials having an electrically insulating, thermally conductive filler material and another thermally and electrically conductive filler material. These partially insulating thermoplastic materials and the electrically conductive thermoplastic materials must be joined in a composite, in order to obtain each of their properties and thus to be used for the purposes of a well insulated electrical conductor.
The use of carbon fibers for reinforcing thermoplastic materials in composite materials is described in European patent application publication EP 1 988 118 A1. Also here, a heating of the already contacted fibers by contact heat is described.
The production of three-dimensional structures based on composite materials is presented in European patent application publication EP 0 884 153 A1. For this purpose, a molding process is used in which the materials are heated together and are thereby pressed into a three-dimensional shape.
German published patent application DE 10 2009 034 767 A1 involves organic sheet structural components, which consist, in part, of structurally reinforced plastics and thermoplastic materials. These materials are also made as composite materials.
In German published patent application DE 10 2005 027 879 A1, the production of a fiber composite material made of a matrix and a round meshwork embedded in the matrix is described. For producing the round meshwork, for example, hybrid threads are used, which are processed with other plastic fibers, carbon fibers, or glass fibers to form a buckling-resistant fiber composite material.
The composites obtainable from the methods known from the prior art need further improvement with respect to their material properties. In addition, the efficiency of these methods must be improved. For example, composites produced according to the methods of the prior art usually have homogeneity properties that need improvement.
BRIEF SUMMARY OF THE INVENTIONTherefore, one object of the present invention is to at least partially overcome at least one of the disadvantages arising from the prior art. In particular, the material properties of the composite materials should be improved, while simultaneously increasing the efficiency of the production method.
In addition, one object according to the invention consists in improving the adhesion of the individual layers in the composite.
Furthermore, one object according to the invention is to reduce the formation of gas bubbles when the layers to be processed into the composite according to the invention are placed one on the other. In this way, a composite that is as uniform as possible should be obtained having a smooth surface.
In addition, one object according to the invention is to prepare a composite having as few flaws as possible in a way that is as efficient as possible.
The invention contributes to a solution for at least one of the objects above as described and claimed below.
In a first aspect, the invention relates to a device including:
a holder region including a first holder for a first thread and at least one further holder for at least one further thread; and
at least one contact area for contacting the first thread and the at least one further thread, wherein at least one radiation source is provided between the holder region and the contact area.
The device is used to bring a first and at least one further thread in contact with each other, so that a fiber-reinforced composite or a fiber-reinforced composite precursor, also called composite precursor, is produced. The composite precursor can be processed further into a fiber-reinforced composite, which is also designated as a fiber composite material. The thread, also designated as fiber or fabric, can be made of any material that one skilled in the art would seek out for forming a fiber composite material. For example, carbon, glass, ceramic, or plastic materials, for example in the form of fibers, or combinations thereof could be used as starting components. Hybrid threads could also be used, which already contain more than one starting component. Preferred hybrid threads include, in addition to plastic, also glass or carbon or a combination of these two materials. Depending on the later use, the threads or fibers can have inorganic or organic additives, in order to increase or decrease, for example, the electrical conductivity or thermal conductivity of the composite material. The plastic materials preferably provided as fibers can be thermoplastic materials or duroplastic materials or a combination thereof. The plastic materials are preferably selected from the group consisting of polyamide (PA), polybutylene terephthlate (PBT), polyester, polyester amide, polycarbonate (PC), polyethylene (PE), polyether ketone (PEK), polyacrylonitrile (PN), polyolefins, polyimide (PI), polyurethane (PU), rubber, and aramids, as well as at least two of these materials. Preferably, the materials are selected from the group consisting of polypropylene (PP), poly(bis-benzimidazo-benzophenanthroline) (BBB), polyamide imides (PAI), polybenzimidazole (PBI), poly(p-phenylenebenzo-bisoxazole) (PBO), poly(p-phenylenebenzo-bisthiazole) (PBT), polyether ketone (PEK), polyether ether ketone (PEEK), polyether ether ketone ketone (PEEKK), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyoxymethylene (POM), polyvinylidene fluoride (PVDF), polyetherimides (PEI), polyethersulfone (PESU), poly(m-phenylene-isophthalamide) (PMIA), poly(m-phenylene-terephthalamide) (PMTA), poly(p-phenylene-isophthalamide) (PPIA), poly(p-phenylene-pyromellitimide) (PPPI), poly(p-phenylene) (PPP), poly(phenylene sulfide) (PPS), poly(p-phenylene-terephthalamide) (PPTA), polysulfone (PSU), polyethersulfone (PESU), and neoprene, as well as at least two of these materials. Especially preferred are materials selected from the group consisting of PES, PEEK, PEI, PPA, PPS, and PI or at least two of these materials. By processing different materials, the different properties of the materials are combined in the composite. Thus, through the suitable selection of a plastic, the heat resistance of a composite can be positively influenced, while the introduction of carbon can influence the electrical conductivity or tear and tensile strength. For increasing the electrical conductivity, metals can also be co-processed as threads or as additives, for example in the form of particles.
After contacting the first thread or one of the at least one further thread with the first thread or with one of the at least one further thread in the contact area, for example in a subsequent step, the composite precursor, preferably present as a profiled piece, can be consolidated, that is, strengthened. This consolidating is often performed by heating the composite precursor. Here, temperatures often lie in a range of 180 to 380° C., preferably in a range of 200 to 300° C., and especially preferred in a range of 210 to 270° C. In general, in selecting the temperatures these should lie above the softening temperature of the plastics, but still below the temperature at which a decomposition of the plastics would be observed during the consolidating period. The consolidation can also be performed under pressure. Here, pressures often lie in a range of 100 mbar to 30 bar, preferably in a range of 200 mbar to 20 bar, and especially preferred in a range of 250 mbar to 10 bar. Here, for example, other contacting steps with already contacted threads or with or without preheating can also be performed. The thread or the fabric can have different shapes. If the thread is a non-woven thread or a thread processed in some other way, the structure is preferably a string-shaped structure, which can preferably have a length in a range of 1 to 100 kilometers.
The individual strings, filaments, or fibers of the thread preferably have a thickness in a range of 1 μm to 100 μm and preferably in a range of 1.1 to 15 μm. The thread can preferably have a thickness in a range of 0.05 mm to 10 mm, preferably in a range of 0.1 to 5 mm, especially preferred in a range of 1 to 3 mm. If the thread is for a woven fabric, knitted fabric, scrim, or tape, then this can preferably have a mass per unit area in a range of 50 g/m2 to 5000 g/m2, preferably in a range of 100 to 1000 g/m2, and especially preferred in a range of 100 to 200 g/m2.
The first thread or the at least one further thread can also be laid on the holder in a woven, braided, or knitted state, as well as a unidirectional tape. Here, the woven, braided, or knitted structure can be produced by processing fibers of different starting materials. The starting materials can be the materials already mentioned for the threads or any conceivable combination of these materials.
In addition to threads, also knitted fabric, scrims, or tapes, preferably so-called unidirectional tapes, can be used. Unidirectional tapes generally have a plurality of interconnected individual threads lying one next to the other and running in the same direction. For these tapes, the designs for threads apply accordingly. For example, these tapes can preferably have a mass per unit area in a range of 50 g/m2 to 5000 g/m2, preferably in a range of 100 to 1000 g/m2, and especially preferred in a range of 100 to 200 g/m2.
The first thread and also the at least one further thread are attached to a holder. Preferably, the threads are wound on the holder, so that they are easily accessible, by simply unrolling them, during the processing of the threads. The holders are constructed, for example, as rods, for example in the form of a bobbin or spool, around which the thread is wound. If the thread is already in a woven, braided, or knitted state, then the holder has, for example, a flat structure in the form of a layer. The holder can be made of any material that is suitable for use in the device. Preferably, the holder is made of wood or plastic, but it could also be made of metal or a ceramic. Its dimensions are adapted to the dimensions of the device. The length of the rod-shaped holder can be, for example, in a range of 1 to 50 cm, preferably in a range of 1 to 20 cm, and especially preferred in a range of 2 to 10 cm. The diameter of the rod-shaped holder can be, for example, in a range of 1 to 100 mm, preferably in a range of 5 to 50 mm, and especially preferred in a range of 10 to 40 mm.
The first and the at least one further holder together form a holder region of the device. If the device has a housing, then the holder region can be arranged inside but can also be arranged outside the housing. The holders can be surrounded at least partially by a holder housing. This holder housing can, for example, shield radiation from the radiation source from the thread on the holder, in order to prevent, for example, a premature aging of the thread. The holder region is preferably constructed so that it makes the thread accessible in the device without hindrance. The holder region, however, should be arranged away from the radiation source and the contact area, so that the thread on the holder cannot be prematurely impaired, for example, by radiation, temperature, pressure, or contaminating particles. In order not to allow for an unnecessarily long transport path for the thread from the holder to the radiation source and the contact area, however, the holder region should also not be too far away.
The device also has a contact area. This contact area is used for contacting the first thread and the at least one further thread that can also be provided, as already mentioned, as a woven fabric. Preferably, the contact area is constructed so that at least one of the threads can be drawn into this area. The contact area can have, for example, a length extent in a range of 0.1 mm to 10 m, preferably in a range of 0.5 mm to 1 m, especially preferred in a range of 1 mm to 30 cm. The length extent is usually oriented to the size of the area in which the threads, fabrics, or tapes are combined and are processed into the pre-composite by wrapping processes, such as braiding, crocheting, non-crimp laying, or knitting of at least two of the threads, fabrics, or tapes. The contact area can have, for at least one of the threads, a guide, usually in the form of a preferably elongated recess. The length extent here depends on the thread being used. For example, if the thread is a thread that has not yet been woven having a thickness in a range of 0.1 to 10 mm, then the length extent of the contact area is a few millimeters to 10 cm. If, however, the thread is a thread that has already been woven, the contact area can be several meters. In this range of the contact area extent, the at least two threads meet. Preferably, the contact area is located within the housing or within an opening of the housing, if the device has a housing. The resulting composite or composite precursor is led out from the device through the opening in the housing, in order to then be subject to possibly additional processing steps. Due to the arrangement of the contact area relative to the radiation source and to the holder region, at least the first thread or at least one of the at least one further thread is heated by the radiation of the radiation source. The contact area can here have different constructions in size and geometry, as long as it allows a contacting of at least the first thread and at least one of the at least one further thread. Thus, the contact area for single threads can have a size in a range of a few, preferably in a range of 1 to 10,000 cm3 and especially preferred can also be several cubic meters. The first thread can consist of the same material as the at least one further thread. The first thread can be made alternatively from a different material as the at least one further thread. As already mentioned, one of the threads can already exist in an already woven, braided, or knitted state. In turn, the first thread or at least one of the at least one further threads or all of the threads that are contacted in the contact area have been led through the radiation area of the radiation source.
The device further has at least one radiation source, which is provided between the holder region and the contact area. The thread is preferably guided from the holder in the holder region past the radiation source to the contact area. In this way, it is heated by the radiation of the radiation source and contacted in the contact area with at least one further thread. The further thread can also be led past the radiation source, but it can also be led directly to the contact area from the further holder without pre-heating. In this way, one part of the threads can be brought into the contact area in a pre-heated state and another part of the threads can be brought into this area in a not pre-heated state. It is preferred according to the invention that at least one part of the threads is uniformly pre-heated across its cross section by the radiation source. Uniform is here to be understood preferably as a deviation from the target temperature in Celsius of less than 5%; this corresponds, for a pre-heating according to the invention of 200° C., to a deviation of +10° C. Deviations less than +5° C. from the target temperature are preferred, and +2° C. are especially preferred.
The radiation source can be any radiation source that is known to one skilled in the art and allows a temperature increase to be generated in its environment. This can be a radiation source that emits radiation in the visible but also in the non-visible range. This preferably involves electromagnetic radiation, preferably thermal radiation or infrared radiation. The at least one radiation source can here emit radiation in a wavelength range from 200 nm to 1 mm, preferably in a wavelength range from 500 nm to 20 μm, especially preferred in a wavelength range from 780 nm to 10 μm. The radiation source can also be multiple radiators that can preferably be arranged in different geometries relative to each other. Together, they form the radiation area of the device. For example, they can be several rod-shaped radiators, which can be arranged in a circle or one next to the other. Alternatively, they can also be multiple point-source radiators. Preferably, a homogeneously heated radiation area is generated within the device by the radiation source. It is further preferred to guide at least one part of the threads through this homogeneously heated radiation area. In this way the most uniform possible heating of the threads can be achieved.
The device can also have a housing that surrounds at least parts of the device. Thus, at least the radiation source can be surrounded by a housing, in order not to let the radiation radiate into the surroundings. Furthermore, at least one of the holders or the contact area can also be located in the housing. The housing is adapted in its dimensions to the previously described parts that it can hold. Thus, the housing can have a volume in a range of 1 to 50,000 liters, preferably in a range of 10 to 20,000 liters, especially preferred in a range of 100 to 10,000 liters. Preferably, the housing is made of a material that is not changed in form and function by the radiation. This can be, for example, heat-resistant plastic or metal. In the housing there can also be temperature-regulating units, preferably ventilation devices, for example in the form of fans, which prevent the device from overheating.
In one preferred construction of the device, at least one of the at least one radiation source is an infrared radiator. An infrared radiator emits electromagnetic waves in a wavelength range from 700 to 20,000 nm, preferably in a range of 1000 to 10,000 nm, especially preferred in a range of 1500 to 2000 nm.
Thermal infrared radiators are characterized, in particular, by the wavelength at which the maximum spectral emission occurs. This peak wavelength is directly associated with the temperature of the emitting surface. In one preferred embodiment of the device, at least one of the at least one radiation source has an output in a range of 1 to 100 W/cm, preferably in a range of 2 to 50 W/cm, especially preferred in a range of 5 to 20 W/cm, with respect to the length of the radiator.
In a further preferred embodiment of the device, at least one of the at least one radiation source has a ring-shaped construction. Here, for example, several elongated radiators can be arranged in a ring or a radiator can be constructed as a ring. It is further preferred to construct the radiation source with a conical shape. This can be realized, in turn, by arranging several ring-shaped radiators having different diameters or with one radiator that produces a conical shape in several loops. For a conical shape it is further preferred that the cross section of the cone turned toward the holder region be greater than the cross section of the cone turned toward the contact area.
In one preferred embodiment of the device, a thread line extending through the first thread between the holder region and the contact area lies within a ring formed by the ring-shaped radiation source. For example, a plurality of threads guided into the contact area starting from the holder region can be uniformly irradiated and heated.
It is further preferred that the holder region be movable relative to the contact area. Preferably, the first holder and the at least one further holder move about an axis running through the contact area, wherein preferably the holders perform a rotational movement about this axis. In addition, the holder region is preferably movable relative to the radiation source. Here it is preferred that the radiation source be rigid and the holder region and preferably the holders be movable relative to the radiation source. Through the movable arrangement of the holder region relative to the contact area it is ensured that the tension on the thread during the processing in the device is not large enough that the thread becomes too thin or tears. In addition, this movement contributes to the most uniform possible heating of the threads.
In one preferred construction, at least one reflector is provided between the holder region and the contact area. The at least one reflector can be arranged parallel to the alignment of the radiation source. Several reflectors could also be arranged around the radiation source, so that the radiation area is heated homogeneously. This is especially preferable in a conical arrangement of the radiation source and reflectors. Thus, reflectors can be located within or outside the cone, and these reflectors can reflect the radiation of the radiation source back into the radiation area. The at least one reflector can also consist of any material that is suitable for the reflection of electromagnetic waves. These are primarily metallic surfaces. Thus, the at least one reflector can have a metallic surface selected from the group consisting of aluminum, iron, particularly steel, silver, gold, and copper, or at least two of these materials. Preferably, at least the surface of the reflector consists of aluminum. The reflectors can be used, on one hand, such that the radiation area is heated homogeneously and, on the other hand, such that the energy of the radiation source is used efficiently. In one preferred embodiment, the reflector is a specular or diffuse reflecting surface. Specular reflecting surfaces are preferably blank, polished, or lapped. The diffuse reflecting surfaces, in addition to the materials named above, can be also ceramic reflectors, preferably having a sand-blasted or glass-bead surface structure.
In one preferred embodiment, the contact area has a thread pulling device or a thread pulling device follows the contact area or both. The thread pulling device can have different shapes depending on what shape or form the thread or woven fabric has. The thread pulling device can be constructed, for example, in the shape of a gripper that pulls the precursor composite material produced at the contact area out from the contact area. An alternative construction of the thread pulling device can be bands or rolls that enclose the produced composite material or precursor composite material and pull the material away from the contact area by moving the rolls or bands. This type of movement is known from the pultrusion method known in the prior art, whose use is regulated, for example, in the standard EN 13706-1:2002. Through the pulling movement of the thread, the thread or the woven fabric moves from the holder to the contact area, preferably uniformly. If it is a thread or woven fabric that is to be heated before contact, then the thread or the woven fabric is automatically guided past the radiation source on the way from the holder to the contact area. The thread pulling device pulls the thread or the woven fabric, for example, at a speed in a range of 1 mm/min to 100 m/min, preferably in a range of 10 mm/min to 10 m/min, especially preferred in a range of 10 cm/min to 5 m/min. It can also be provided in the device according to the invention that at least two groups of holder and contact areas follow one after the other having a radiation area provided between these areas. This is always preferred if a pre-composite or a composite produced from this is to be produced with two or more layers. In this case, a thread pulling device can follow at least one contact area. Therefore, the thread pulling device can not only move the thread or tape directly but also indirectly by a pre-composite or composite. If two-dimensional structures, such as non-crimp fabrics, knitted fabrics, woven fabrics, or tapes are used according to the invention, these can also be moved accordingly by the thread pulling device.
In one aspect of the device according to the invention, the contact area has a forming tool. The forming tool can have any shape that is suitable for holding and preferably also guiding the at least two threads. The forming tool can here hold at least the first thread and at least one of the at least one further threads together. This can be, for example, an elongated forming tool, for example, a tube or a mandrel. Preferably, the threads, woven fabrics, or tapes to be contacted are turned around the forming tool and here placed or braided one above the other. In this way, a tubular profile of the fiber composite material can be obtained. The forming tool can also have a triangular, rectangular, or polygonal, elliptical, or rhombic cross section, so that profiles of the composite or of the composite precursor of a wide range of shapes and forms can be obtained.
Furthermore, an embodiment according to the invention is preferred such that at least the first thread or the further thread is arranged between the holder region and the contact area relative to the at least one radiation source, so that the irradiated part of the first thread or the further thread can be heated from a first temperature T1 to a second temperature T2. Through the irradiation by the radiation source, the threads that have been guided through the irradiation area have an elevated temperature T2 relative to the original temperature T1 that the corresponding thread had on the holder. The temperature T1 of each thread should preferably be below the softening point of the thread, so that the thread or woven fabric does not tear while it is guided to the contact area. Conventionally, the temperature T1 is in a range of −10 to 60° C., preferably in a range of 5 to 40° C., especially preferred in a range of 15 to 40° C. By guiding the thread through the radiation area, the thread is preferably heated to a temperature T2. Here, temperatures T2 often lie in a range of 180 to 380° C., preferably in a range of 200 to 300° C., and especially preferred in a range of 210 to 270° C. In general, for the selection of the temperatures T2 it is applicable that these are above the softening temperature of the plastics, but not below the temperature at which a decomposition of the plastics would be observed during the period of irradiation.
To be able to perform a suitable control of the temperature relationships in the device, the device according to the invention can further have a pyrometer, which is used for contact-less measurement of the thermal radiation in a certain area in the device. In this way, the control of the at least one radiation source can be performed, so that an overheating of the threads or woven fabric can be prevented. Thus, in addition to the pyrometer, another control unit can be connected to the pyrometer and to the radiation source, wherein this control unit controls the energy input into the radiation source, so that a deviation of the temperature T2 of the thread before it enters into the contact area can be ensured in a range of 0.1 to 10° C., preferably in a range of 0.5 to 5° C., especially preferred in a range of 0.5 to 2° C. Especially for the use of hybrid threads, the control of the temperature T2 is very demanding, because these contain at least two components that have different softening points. Because the thread is to be pre-heated sufficiently on one side, but must not become too hot on the other side, in order to prevent damage, in the hybrid threads, a temperature should be selected below the decomposition temperature, but preferably below the softening temperatures of the more temperature sensitive component.
Preferably, a so-called quotient pyrometer is used, which is directed toward the threads close to the contact point and is directed, as long as the threads do not fill up the entire measurement area of the pyrometer, toward a surface that is especially cold or is provided in some other way with especially low emissions or reflections. Preferably, this is an opening on the opposite wall behind which is located a space having cool or cooled walls. As support for the temperature control, a ray-tracing process can also be used. Here, the emission characteristics of the radiation source are measured, and then it is calculated by mathematical computations how the thermal radiation will look in the radiation area being used. In the ray-tracing process it is preferred that, starting from the modeled radiation source or sources, rays are traced that radiate in random directions and from randomly selected positions. For each of these rays it is then calculated when and where they will meet other surfaces and how they will behave there, that is, whether these surfaces will absorb, scatter, or reflect the rays. Each ray is traced until its energy falls, for example below a certain threshold, or has reached a previously defined number of surfaces. For achieving a high accuracy, the following are important:
the accuracy of the radiation source models,
the accuracy of the optical surface descriptions,
the detailing of the model of the device to be calculated,
the selected cut-off criteria, and
the number of traced rays.
For a device according to the invention, for relevant results, approximately 1,000,000 to 10,000,000,000 rays are traced. For determining the parameters to be calculated, virtual detectors are positioned along the thread paths by software, and these detectors determine the output, spectral irradiation intensity, spectral beam density, or other parameters to be determined by integrating rays passing through each detector. A device for the ray-tracing process is available, for example, from ZEMAX LLC., Delevue, Wash., USA.
In a further aspect of the invention, a method for producing a composite is described, including the steps:
I. preparation of a first thread and at least one further thread at a temperature T1;
II. irradiation of at least one part of the first thread or the at least one further thread or both; and
III. contacting of the first thread and the at least one further thread, wherein at least one of these threads has a contact temperature T2 greater than T1, wherein a tensile force acts on at least one of these threads during the contacting.
In general, the embodiments relative to individual features in connection with the device according to the invention are also applicable to the method according to the invention and vice versa. In the method, the threads could have the composition already described for the device. The temperature T1 of the first thread and of the at least one further thread could be identical or could deviate from each other. Preferably, the temperatures T1 of the first thread and of the at least one further thread are approximately identical. This is especially advantageous because the threads could be stored in a common holder region. Providing the first thread and the at least one further thread with a temperature T1 is preferably performed in a holder region with holders, as already described for the device. As already mentioned for the device, the temperature T1 can correspond to the surrounding room temperature, which is usually between 5 and 40° C. For T1, the same ranges can be used as described for the device. The thread that is led past the radiation source and irradiated is here heated to a temperature T2 above the temperature T1. This temperature T2 also lies in the ranges as described above for the device. After the irradiation of the at least one thread, this thread heated to the temperature T2 is contacted with the first or the further thread in a contact area. Both threads or only one of the two threads could have a temperature T2. In this process, a tensile force acts on at least one of these threads. This tensile force can be performed by a thread pulling device as was already described for the device.
In the described way, for example, a tube-shaped, round meshwork can be produced that has, for example, a cylindrical shape. According to the requirement profile, the cross section of the meshwork can have or can become a different shape and can have a different size. Normally, the round meshworks have a circular cross section. For such applications, in which the rod-shaped fiber composite material is constructed for holding one or more lines for current or fluids, circular cross sections are considered advantageous. However, elliptical, rhombic, triangular, rectangular, or more complex cross sections are also conceivable and in individual use cases are expedient, for example in the production of parts for car body construction. Because the composite materials or the composite precursors are usually produced continuously, for example in the pultrusion method, the produced composite can be subsequently cut to the necessary size in a cutting process. In addition, the composites can be fed to other refining processes before or after the cutting, for example, spraying with paints, coatings, or other polymers.
In one preferred method, the first thread contains carbon or glass or both. As already described for the device, the first thread or woven fabric, but even the at least one further thread that is provided, can have different materials. For example, one of the threads could be made of a composite made of a plastic with carbon or glass. However, it could also consist of a carbon, for example a carbon fiber alone, or from a glass, for example a glass fiber alone, or from a mixture of the two. All of the conceivable mixtures could be provided, for example, those described for the device.
Furthermore, the irradiation is preferably performed by infrared radiation. As already described for the device, the irradiation can be performed in a broad wavelength range. If it is performed with the help of an infrared radiator, the wavelength is preferably in a range of 780 to 10,000 nm.
In addition, the irradiation is preferably performed with an output in a range of 1 to 100 W/cm. The output here relates to the length of the radiator. The radiator can reach a temperature in a range of 600 to 3000° C., preferably 1000° C. to 2400° C., and especially preferred from 1250° C. to 1800° C.
Furthermore, the contacting preferably takes place in the presence of a polymer. This polymer can be one from the group as described for the thread in the device or a material that is different from this thread. Preferably, it is a thermoplastic material.
In addition, after contacting, a composite precursor is preferably obtained, wherein the composite precursor is brought to a temperature T3 above the temperature T2. As already described for the device, the previously described composite precursor obtained by the method can be processed in additional steps. One possibility for further processing is in a pultrusion method, in which the produced composite precursor is heated to a temperature T3 that is higher than the temperature T2 at which the at least two threads were contacted. This temperature T3 should be higher than the softening point of one of the components of the composite precursor. The temperatures T3 can often be in a range of 180 to 380° C., preferably in a range of 200 to 300° C., and especially preferred in a range of 210 to 270° C. In general, it is applicable for the selection of the temperatures that these are above the softening temperature of the plastics, but still below the temperature at which the plastics would decompose during the period of consolidating. This processing of the composite precursor with increased temperature is used to fuse, cement, or sinter the components of the composite precursor to each other, so that after the hardening, a consolidated composite, that is, a composite having a desired density, is produced. In another aspect, the previously described device is used in the previously described method.
In another aspect, a composite is proposed that can be obtained according to the method described above. This composite can be used for different purposes. For example, such composites are often used, due to their high resistance to tearing and their tensile strength, as a replacement for heavy metal parts in car body or aircraft construction.
In another aspect of the invention, a product is proposed containing a composite as described above and another component that is different from the composite. Such products can be, for example, the three-dimensional structures described in German published patent application DE 10 2009 034 767 A1 or European patent application publication EP 1 988 118 A1. Such products can also be vehicles that move, in particular, driven, relative to land, water, or air. Such vehicles can be, for example, aircraft, ships, bicycles, or motor vehicles. Such products could also be buildings or parts of buildings, such as roofs, facades, windows, or ductwork systems.
The embodiments of the radiator according to the invention also apply accordingly to the device according to the invention for material testing, and also to the method according to the invention for material testing. This applies, in particular, for materials and spatial constructions.
The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. In the drawings:
In
In the housing 15 there is at least one radiation source 20, here in the form of several ring-shaped radiators 20. The ring-shaped radiators 20 form a ring 25. This ring 25 surrounds a thread line 38. This thread line 38 can be formed either from only the thread 35 or from two threads 35 and 45. In a conical arrangement, the ring-shaped radiators 20 surround a tube 120, which is guided through the openings 70 and 70′ of the housing 15. The ring-shaped radiators 20 are surrounded on their inner side facing the tube 120 by an inner reflector 90 and on their outer side facing away from the tube 120 by an outer reflector 80. Together with the reflectors 80 and 90, the ring-shaped radiators 20 represent the radiation area 50. During the use of the device 10, at least a first thread 35 or also further thread 45, each of which is located on a holder 30 and 30′, respectively, is introduced into this radiation area 50. The two holders 30 and 30′ form the holder region 40 that is located outside of the radiation area 50. On the opposite side of the radiation area 50 there is a contact area 60. Here, the first thread 35 and the further thread 45 are joined together after being heated by the radiator 20. In this case, the contact area 60 is located on the surface of the tube 120, which is why the tube 120 is also designated as an inner profile 120, because it gives its profile to the resulting composite precursor 130. As already mentioned, the tube 120 can also have an oval or polygonal surface. The tube 120 or the composite precursor 130 or both move in the pulling direction 150 away from the device 10. The pulling device is not shown here. Due to this pulling, the threads 35 and 45 are automatically unwound from the holders 30, 30′ and fed to the radiation area 50. Furthermore, the holders 30, 30′ are arranged in a circle around the axis of the elongated tube-shaped forming tool 120.
The contact area 60 can also be a part of the radiation area 50, as it is shown here, but this is not a requirement. In order to prevent overheating of the radiator 20 and the radiation area 50 as well as the reflectors 80 and 90, fans 100 are arranged at several locations of the device 10. These fans 100 are used primarily for cooling the reflectors 80 and 90 and pull in cool air from the surroundings, in order to move it into and through the device 10 in the direction of motion 110.
The coil temperature of the ring-shaped radiators 20 is in a range of 1200 to 1500° C. in the application. The output in the individual radiators 20 is in a range of 5 to 20 W/cm with respect to the radiator length.
Starting with unidirectional tapes that consist of Hexcel APC2 carbon fibers (available from Hexcel Inc., Santa Clara, Calif., USA) and a PEEK matrix (available from VicTrex plc., GB), wherein the fiber content by volume in the consolidated tape is 45% and the mass per unit area is 300 g/m2, multi-layer pultruded profiles are produced. The unidirectional tapes are produced by Suprem SA (Switzerland) according to a patented process from the materials mentioned above and, after consolidating into 6-mm wide bands, the tapes are cut and wound. The unidirectional tapes produced in this way on the individual tape rolls have a length that corresponds to the original rovings of Hexel APC2 fiber, but at least 1000 m.
Then, in a first station 38, tape rolls are mounted on a holder region constructed as a braiding wheel, from which 19 tapes in the clockwise direction and 19 tapes in the counterclockwise direction are braided into a first tube with a basket weave in a contact area of the first station. Between the holder region and the contact area, the tapes are heated to a temperature of 350° C. by being passed through infrared radiation sources.
This first tube is wrapped around three more times with a layer having a basket weave in three additional stations also provided with 38 tape rolls under the same conditions. After the fourth station, the resulting four-layer pre-composite is consolidated at a temperature of 375° C. to a composite having a diameter of 60 mm and a circular cross section. This composite has a nearly smooth surface and a high uniformity in the fiber distribution.
COMPARATIVE EXAMPLEThe example is performed without passing the tapes through an infrared radiation source according to the invention. This produced a composite having a surface that was made rough by the formation of bubbles and had a distinctly worse homogeneity with an about 60% lower throughput rate.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
Claims
1.-19. (canceled)
20. An irradiation device comprising:
- a holder region (40) comprising a first holder (30, 30′) for holding a first thread (35) and at least one further holder for holding at least one further thread (45),
- at least one contact area (60) for contacting the first thread and the at least one further thread, and
- at least one radiation source (20) located between the holder region and the contact area for irradiating at least one of the first thread and the at least one further thread.
21. The irradiation device according to claim 20, wherein at least one of the at least one radiation source comprises an infrared emitter.
22. The irradiation device according to claim 20, wherein at least one of the at least one radiation source has an output in a range of 1 to 100 W/cm.
23. The irradiation device according to claim 20, wherein at least one of the at least one radiation source has a ring-shaped design.
24. The irradiation device according to claim 23, further comprising a thread line (38) extending through the first thread between the holder region and the contact area, the thread line lying within a ring (25) formed by the ring-shaped radiation source.
25. The irradiation device according to claim 20, wherein the holder region is movable relative to the contact area.
26. The irradiation device according to claim 20, further comprising at least one reflector (80, 90) located between the holder region and the contact area.
27. The irradiation device according to claim 20, further comprising a thread pulling device (170) associated with and/or following the contact area.
28. The irradiation device according to claim 20, further comprising a forming tool (120) in the contact area.
29. The irradiation device according to claim 20, wherein at least one of the first thread or the further thread is arranged between the holder region and the contact area relative to the at least one radiation source, such that an irradiated part of the at least one of the first thread or the further thread can be heated from a first temperature T1 to a second temperature T2.
30. A method for producing a composite, the method comprising the following steps:
- (a) preparing a first thread and at least one further thread each at a temperature T1;
- (b) irradiating at least one part of the first thread and of the at least one further thread; and
- (c) contacting the first thread and the at least one further thread, wherein at least one of the threads has a contact temperature T2 above T1, and wherein a tensile force acts on at least one of the threads during the contacting.
31. The method according to claim 30, wherein at least the first thread contains at least one of carbon and glass.
32. The method according to claim 30, wherein the irradiating step is performed by infrared irradiation.
33. The method according to claim 30, wherein the irradiating step is performed at an output in a range of 1 to 100 W/cm.
34. The method according to claim 30, wherein the contacting step is performed in the presence of a polymer.
35. The method according to claim 30, wherein after the contacting step, a composite precursor is obtained, and wherein the composite precursor is brought to a temperature T3 above the temperature T2.
36. A method for producing a composite according to claim 30, the method using an irradiation device comprising:
- a holder region (40) comprising a first holder (30, 30′) for holding the first thread (35) and at least one further holder for holding the at least one further thread (45),
- at least one contact area (60) for contacting the first thread and the at least one further thread, and
- at least one radiation source (20) located between the holder region and the contact area for irradiating at least one of the first thread and the at least one further thread.
37. A composite produced according to the method of claim 30.
38. A product comprising a composite according to claim 37 and another component different from the composite.
Type: Application
Filed: Mar 22, 2012
Publication Date: Feb 13, 2014
Applicant: HERAEUS NOBLELIGHT GMBH (Hanau)
Inventor: Sven Linow (Darmstadt)
Application Number: 14/111,875
International Classification: D01F 8/04 (20060101);
