Units manufacture semi-finished products felt
Ref document number : Country of ref document : DE. Effective date : Independent claims are included for: 1 the semi-finished textile product, preferably prepreg, comprising carbon fibers pre-impregnated with the matrix material; and 2 a carbon fiber reinforced composite material obtained by hardening or thermally deforming and optionally after compacting the semi-finished textile product. The present invention relates to a process for producing a textile semifinished product, in particular a prepreg, from carbon fiber preimpregnated with a matrix material, a textile semifinished product obtainable by this process, in particular prepreg, and its use in particular for the production of composite components, in particular for the production of Exterior skin and structural components for motor vehicles and transport vehicles. Carbon fiber-containing composite materials, such as carbon fiber reinforced plastic CFRP , which is composed of an example of phenolic resin or epoxy resin matrix in which carbon fibers or graphite fibers embedded in one or more fiber layers, or carbon fiber reinforced carbon CFC , which consists of a carbon matrix , in which carbon fibers or graphite fibers are embedded in one or more fiber layers, have a high strength and rigidity, especially in the fiber direction and are also characterized by a low weight compared to other materials, such as steel, by a low Thermal expansion and excellent thermal shock resistance.VIDEO ON THE TOPIC: 5 Incredible Machines for Manufacturing at Home #2
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Variety Control of a Semi-Finished Product Within a Group Technology Manufacturing System
Ref document number : Country of ref document : DE. Effective date : Independent claims are included for: 1 the semi-finished textile product, preferably prepreg, comprising carbon fibers pre-impregnated with the matrix material; and 2 a carbon fiber reinforced composite material obtained by hardening or thermally deforming and optionally after compacting the semi-finished textile product. The present invention relates to a process for producing a textile semifinished product, in particular a prepreg, from carbon fiber preimpregnated with a matrix material, a textile semifinished product obtainable by this process, in particular prepreg, and its use in particular for the production of composite components, in particular for the production of Exterior skin and structural components for motor vehicles and transport vehicles.
Carbon fiber-containing composite materials, such as carbon fiber reinforced plastic CFRP , which is composed of an example of phenolic resin or epoxy resin matrix in which carbon fibers or graphite fibers embedded in one or more fiber layers, or carbon fiber reinforced carbon CFC , which consists of a carbon matrix , in which carbon fibers or graphite fibers are embedded in one or more fiber layers, have a high strength and rigidity, especially in the fiber direction and are also characterized by a low weight compared to other materials, such as steel, by a low Thermal expansion and excellent thermal shock resistance.
Because of these advantageous properties, composite materials containing such carbon fibers are used in many technical fields and in particular increasingly in the automotive industry, for example, as a material for structural components or for outer skin components of a motor vehicle. However, the composite materials currently used for this have a number of disadvantages. For example, automotive structural members are typically fabricated from carbon fibers in the form of composites containing anisotropic gusset structures.
However, structural components are often exposed to isotropic load conditions, which is why these composites are often made up of several, with each other specifically oriented gel layers, to take into account these isotropic load conditions. Therefore, the manufacturing process for such composites is very expensive, which is why these composites are expensive.
Another disadvantage of these materials is their comparatively poor drapability. On the other hand, outer skin components or visible components of motor vehicles are usually made of composite materials which contain carbon fibers in the form of tissue structures.
These can be produced comparatively inexpensively by a resin injection process RTM process, "Resin Transfer Molding" process. However, these materials have, inter alia, an unsatisfactory surface quality. For example, the surface quality is adversely affected by the fact that an increased shrinkage of the matrix material occurs at the crossing points of the fabric, as a result of which the fabric structure is visible on the surface of the composite material.
For these reasons, there is a need for composites containing carbon fibers which have improved properties, such as, in particular, better surface quality and better drapability, which are of comparatively simple construction, and which can be produced comparatively inexpensively.
In particular, there is a need for semi-finished products, in particular a prepreg, from corresponding composite materials, which can be easily and inexpensively processed to the desired end products, and for a method by which such semi-finished products, in particular prepregs or end products made of composite materials are produced easily and inexpensively can.
In particular, there is a need for corresponding materials which have as high as possible a content of recycled fibers in order to meet the recycling rate for motor vehicles required in the ELV Act, and for manufacturing processes therefor. The object of the present invention is therefore to provide a process for producing a textile semifinished product, in particular a prepreg, from carbon fibers preimpregnated with a matrix material, which can be carried out simply and inexpensively, in which a high proportion of recycled fibers can be used, and which leads to a textile semi-finished product, which has an excellent surface quality and good drapability.
According to the invention, this object is achieved by a method for producing a semi-finished textile product, in particular a prepreg, from carbon fibers preimpregnated with a matrix material, which comprises the following steps:.
The use of a nonwoven or felt in process step a can set a targeted anisotropy of the properties, in particular the strength and rigidity, of the semifinished product and the end product subsequently produced therefrom. In addition, the use of a nonwoven or felt in method step a yields a semifinished product with excellent drapability, which is considerably better than the drapability of a semifinished product which contains exclusively knitted fabric or woven fabric as the fiber material.
For the purposes of the present invention, recycled fibers are understood to mean fibers which have been produced from used fibers, the used fibers being able to originate from any used fiber material, such as, for example, woven fabrics, knitted fabrics, such as knitted or knitted fabrics, loops, fiber mats, from fiber strands, from felts, from nonwovens or from composite materials, such as CFC, CFRP, carbon fiber reinforced concrete or the like.
Surprisingly, an excellent impregnation of the carbon fiber fleece or of the carbon fiber felt can be achieved by each of the abovementioned processes, as a result of which textile semifinished product is obtained, in which the fiber material is embedded particularly homogeneously in the matrix.
Due to the quasi-isotropic orientation of the fibers in the plane and the homogeneous distribution of the matrix shrinkage optical abnormalities can be prevented. This was surprising because nonwovens and felts are basically very difficult to impregnate due to their low permeability in the fiber direction.
Such good impregnation, let alone homogeneous embedding of fibers in the matrix, is not possible with other techniques, such as the RTM process, where the injection or resin spreading of the matrix occurs along the textile orientation.
Depending on the application, a more or less high proportion of carbon fibers may be required in the semifinished product, based on the total fiber content. It is also possible, for example, to use stretch-torn filaments or fibers. In particular, mixtures of carbon fibers and fibers of a thermoplastic can be used for the production of the nonwoven or felt, which later allows a direct consolidation of the textile semifinished product to form an organic sheet.
For example, the recycled fibers may be made from a fibrous material preimpregnated with a matrix material, or composite containing fibers, such as CFC or CFK, by comminuting the fiber material preimpregnated with a matrix material or the composite containing fibers before the fibrous material is then crushed the matrix material is dissolved and separated.
The comminution is preferably carried out with a shredder, with a granulator, with an impact mill or with a hammer mill so that particles with a length between 1 and mm are obtained.
In this embodiment, the dissolution of the matrix of the carbon fibers, for example by solvolysis, that is, by contacting the material with an acid, for example with a mineral acid, such as sulfuric acid or nitric acid, with an alkali such as sodium hydroxide, or with a solvent. Alternatively, the dissolution of the matrix from the carbon fibers may inevitably occur during comminution.
According to a further alternative, the removal of the matrix can also be effected by pyrolysis of the matrix material. Thereafter, the matrix can be separated from the carbon fibers by, for example, screening or sifting, the sizing being performed, for example, in a rotary sifter, air classifier or zigzag sifter. Finally, the fiber material obtained can still be coated with size.
As a result, in carrying out the method according to the invention and in particular in carrying out the method step b any resulting stresses are absorbed by the other fiber material, so that the web or the felt is exposed to only low tensile stresses and thus damage or even destruction of the web or Felt is reliably prevented so that it can be processed deformation-free and non-destructive to the semi-finished textile product and then from this to the final product.
In the aforementioned embodiment, the individual fiber materials may be arranged in the form of a laminate or, if possible, the individual fiber materials may be combined together in one layer.
In principle, the laminate may consist of at least one nonwoven layer and at least one fabric layer, at least one nonwoven layer and at least one release layer or a nonwoven fabric with core material, wherein the core material may be, for example, foam, have a honeycomb structure, may be a cardboard core or any other core material can be. In this case, the nonwoven or felt layers in such laminates are preferably located on the outer sides of the laminate, so that the textile semifinished product or the end product produced therefrom has the advantageous surface properties resulting from the use of fleece or felt compared to woven fabric and knitwear.
In a further development of the inventive concept, it is proposed, as another, selected from the above group fiber material to use a fiber material which consists of carbon fibers, glass fibers, polymer fibers and mixtures of two or more of the aforementioned materials. Examples of suitable polymeric fibers include, but are not limited to, polyamide fibers, polyester fibers, polypropylene fibers, polyacrylonitrile fibers, oxidized polyacrylonitrile fibers, as well as fibers of copolymers of two or more of the foregoing materials and blends of two or more of the foregoing materials.
If the fleece or the felt are combined in a layer with each other, such as in In the case of forfeiture of fleece and scrim, the combination of the two fiber materials can be carried out particularly preferably also in the nonwoven or felt production in process step a.
In principle, all thermoplastics, thermosets and elastomers, in each case individually or in a mixture with one another, can be used as the matrix material in process step b. However, good results are obtained particularly when the matrix material is selected from the group consisting of epoxy resins, phenolic resins, vinyl ester resins, polyester resins, polyurethane resins, benzoxazine resins, novolaks, cyanate ester resins, bismaleimide resins, bisoxazolines, polyolefins such as polypropylene, engineering thermoplastics such as polyamides , and any mixtures of two or more of the aforementioned materials.
In the wet pressing process, a blank of the web or felt produced in process step a is placed in an open mold before liquid or solid matrix material is poured, sprayed, spread or laid onto the web or felt before the mold is closed and in the mold, a pressure of preferably between 0.
Due to the pressure in the mold, the same flow paths result on all sides, which is why the matrix material in the nonwoven or in the felt evenly distributed. In order to avoid the effect of excessive tensile forces on the nonwoven or the felt in the prepreg process, this may be carried out independently of whether this is carried out as a powder prepreg process or as a liquid prepreg process, preferably that the nonwoven or the Felt before performing the process step b on one side or, if the nonwoven or the felt is used without the other fiber material, also on both sides with a support material, preferably with a carrier film or with a backing paper coated.
The carrier film may for example be composed of a thermoplastic and may be, for example, a film or a film made of polyester.
In this case, the thermoplastic film or the thermoplastic film may in turn be coated. In the case of a thermoplastic carrier film, the carrier material can be applied, for example by calendering, to the nonwoven or to the felt. In this case, the order of the powdery matrix material, in particular with the latter two methods, selectively on one side of the nonwoven or felt, or this may be done, which is preferred, in particular with the former method, on both sides of the textile fabric.
When the matrix material is a thermoplastic, the powdery matrix material applied to the nonwoven or felt is preferably fixed by fusing onto the nonwoven or felt, the fusing being effected by, for example, passing the powder coated nonwoven or felt through a temperature just above the Melting temperature of the thermoplastic set heating zone can take place. As a result, in the subsequent method steps, a drop of the powder from the nonwoven or felt can be reliably prevented.
In a further embodiment, the matrix material is a thermoset. This is preferably applied to the web or felt in the form of a powdered thermoset prepolymer before the powdered material is melted, preferably at a temperature just above the melting temperature of the thermoset prepolymer but below the crosslinking temperature of the thermoset prepolymer on the web or felt is fixed. A thermoset prepolymer according to the present invention, in accordance with the standard definition of this term, is understood as meaning an oligomer or polymer which can be converted into a thermoset via crosslinking.
In this case, the crosslinking, if the thermosetting prepolymer is sufficiently functionalized, without crosslinking agent, or this can be done with a crosslinking agent. As the crosslinking agent, there may be used, for example, a compound selected from the group consisting of amines, for example, hexamethylenetetramine, acid anhydrides, Lewis acids, radical formers, such as, in particular, peroxides, azo compounds and the like, transition metal compounds, such as transition metal salts, transition metal organic compounds and the like Acids, inorganic acids and any mixtures of two or more of the aforementioned compounds.
Vinyl esters and polyesters are suitable as crosslinking agents, in particular free-radical formers and transition metal compounds, whereas phenol resins are suitable as crosslinking agents, in particular amines, inorganic acids and organic acids and suitable for the other matrix precursors from the above list as crosslinking agents, in particular amines, acid anhydrides and Lewis acids.
Regardless of whether the prepreg process is carried out as a powder prepreg process or as a liquid prepreg process, the impregnation in process step b is preferably carried out by a pressure-temperature treatment, that is to say at elevated temperature and at elevated pressure.
A further subject of the present invention is a semifinished textile product, in particular prepreg, of carbon fibers preimpregnated with a matrix material, which is obtainable by the method described above.
According to a preferred embodiment of the present invention may be embedded in the matrix material, another fiber material, which is preferably selected from the group which of woven, laid, unidirectional UD strands, tapes, nonwovens, felts and any mixtures of two or more of the aforementioned materials.
Further, the semi-finished textile of the present invention has excellent drapability, and therefore, it can be easily and inexpensively processed into the desired end product having high strength and rigidity at comparatively low weight and excellent surface quality.
In particular, in the textile semifinished product according to the invention, due to the use of a nonwoven or felt, by introducing a gradable preferred orientation during the production of the nonwoven, a targeted anisotropy of the properties, in particular of the strength and the stiffness, can be set.
According to a particularly preferred embodiment of the present invention, the semifinished textile product according to the invention is selected by a process selected from the group consisting of prepreg process, wet pressing process, resin infusion process, Folienkaschierverfahren and vacuum assisted VARI method and most preferably by a powder prepreg process, by a liquid Prepreg process or produced by a wet pressing process.
Surprisingly, in the semifinished textile product according to the invention thus produced, the fiber material is embedded in the matrix in a particularly homogeneous manner, as a result of which the resin shrinkage during hardening of the matrix can be at least almost completely prevented.
The semifinished textile product according to the invention can be recycled directly or in a consolidated form into the production process. Exemplary applications are the production of a structural component or an outer hull component of a motor vehicle, a rail vehicle or a transport vehicle from the textile semifinished product. Another object of the present invention is a carbon fiber reinforced composite, which is obtainable by curing a crosslinking matrix of the textile semi-finished product described above.
Furthermore, the present invention relates to a carbon fiber-reinforced composite material which is obtainable by thermoforming and optionally recompressing a thermoplastic matrix of the textile semifinished product described above.
Hereinafter, the present invention will be further described by way of these illustrative but nonlimiting examples.
The carbon fibers had one according to the ASTM D determined carbon content "carbon content" of more than 90 wt.
Furthermore, the carbon fibers were pre-oriented in nonwoven production, so that a certain anisotropy in terms of fiber orientation and thus the mechanical properties was adjusted.
The coating system consisted of a respective unwinding unit for coating paper or carrier paper and the carbon fiber fleece, a coating unit, a first calender, a furnace unit, a second calender, a cooling plate and a take-up unit. Then, the prepreg thus prepared was processed into a carbon fiber reinforced plastic CFRP comprising the nonwoven made of carbon fiber derived from production wastes. For this purpose, several layers of the prepreg were cut to square pieces on a guillotine and centered symmetrically on each other.
With the above method, various CFC's were prepared by varying the temperature used in the curing and the duration of the curing, each obtaining very homogeneous composite sheets. For the above four samples, the 3-point flexural strength, the 3-point flexural modulus, the elongation at break, the density and the fiber volume content were determined. Comparable values were obtained with the other three samples. For the sake of completeness, it should be noted that in the method described above, as an alternative to the epoxy resin, a thermoplastic or thermosetting resin system or other thermosetting resin system may be used, in the form of a solution in an inorganic or organic solvent.
For this purpose, preferred solvents are ketones, such as acetone and methyl ethyl ketone, alcohols, ethers, esters and the like. The procedure for the impregnation is analogous to the previously described method and differs therefrom only in that in the furnace, in contrast to the previously described variant, only the solvent is removed by evaporation.
A carbon fiber fleece produced from production wastes as described in Example 1 was processed by means of a wet pressing process into carbon fiber reinforced plastic CFRP. For this purpose, several layers of the fleece were cut into square pieces on a leverage cutting machine and placed in a mold center-symmetrically on each other.
As a result, very homogeneous composite panels were obtained. A carbon fiber nonwoven made from production waste carbon fibers as in Example 1 was processed by a wet pressing process to carbon fiber reinforced plastic CFRP.
For this purpose, several layers of the web were cut into square pieces on a lever cutting machine and stored in a mold alternately with a respective resin layer between two carbon fiber fleece layers centered symmetrically on each other.
The resin layers were sprayed on, but could also be poured into the mold in the form of a resin film. On a laboratory coating plant, a prepreg was produced from a carbon fiber fleece which consisted of carbon fiber waste waste from SGL ACF GmbH, Germany, and a solid, thermoplastic polymer matrix made from polyamide 6.
Carbon fiber webs and matrix materials prepared as described above were combined by each of the three methods described below. The coating system in this case consisted of a winding and unwinding unit, a powder spreader and a heating field. As a result, an adhesion of the powder to the carbon fiber fleece was achieved. In this process, however, no significant impregnation of the web took place. Following the first coating and fixing, a second coating was carried out analogously to the above-described procedure on the previously uncoated side.
Due to the double-sided coating, a particularly high degree of uniformity and flatness of the powder prepreg has been achieved. However, this process step is optional.
Global Office Supplies (except Paper) Manufacturing Market Report 2019 - ResearchAndMarkets.com
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There are many articles written on this subject by various experts but one thing that I felt was missing was aligning the SAP concept with the real business scenarios or case study. My intent for writing this article is to try and explain the SAP concepts of product costing with the relevant business case. Please note I am intending to cover the business process and align the same with SAP concepts.
wood - semi-finished products - Import export
Global Office Supplies except Paper Manufacturing Market Report provides the strategists, marketers and senior management with the critical information they need to assess the global office supplies except paper manufacturing market. The office supplies except paper manufacturing market consists of sales of office supplies except paper by entities organizations, sole traders and partnerships that produce office supplies except paper. Examples of products made by the establishments in this industry are pens, pencils, felt tip markers, crayons, chalk, pencil sharpeners, staplers, modeling clay, hand operated stamps, stamp pads, stencils, carbon paper, and inked ribbons.
In cases where these groupings correspond with major groups, the major group heading is also in italics. The assembly of products from component parts is considered to be Manufacturing, except in cases where the activity is appropriately classified under Construction. The assembly and installation of machinery and equipment in mining, manufacturing, commercial and other business establishments is classified under the same group of Manufacturing as the manufacture of the item installed. Excluded is the assembly on site of prefabricated, integral parts of bridges, water tanks, storage and warehouse facilities, railway and elevated pedestrian bridges, and lift, escalator, plumbing, sprinkler, central heating, ventilating, air-conditioning, lighting and electrical wiring systems for buildings and mines and all kinds of structures which are construction activities if undertaken as a specialised activity. Establishments specialising in the installation of household appliances, such as stoves and ranges, refrigerators, washing machines and driers, are classified under the appropriate retail trade group. The manufacture of specialised components and parts of and accessories and attachments to machinery and equipment is, as a general rule, classified under the same group as the manufacture of the machinery and equipment for which the parts and accessories are intended.
Send us an e-mail and we will get back to you as soon as possible. Or you can use our contact form. A short message is enough — we will call you back, weekdays from am - pm. Did you know that we supply our customers with undercollar felts for approx. Whether made of pure wool or in combination with innovative synthetic fibres - our undercollar products feature the right materials for any occasion.
Development of Food and Agricultural products processing industries. The Conference recognized the importance of food and agricultural products processing industries in stimulating agricultural development, raising the degree of self-reliance of the developing countries and accelerating their economic growth and sustained progress towards elimination of disparities. It emphasized that the development of these industries had to be based on an integrated approach which would take into full consideration raw material production, post-harvest handling, storage, conservation, processing, marketing and distribution.
The main rationale for reservation of items for exclusive production in the SSI sector were the feasibility of producing an item in the SSI Sector without compromising on quality; level of employment generation, diffusion of entrepreneurial talent and prevention of economic concentration etc. The reservation policy was initiated in with 47 items which was enlarged to items by In , the reservation list was recast into NIC codes which converted these items to Since then, from time to time some items have been added and also some items have been delated from the list.
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The idea becomes a product. Here it is decided that everything was done correctly. Here it is decided whether all the parameters previously defined properly and in the optimal combination have been coordinated. And indeed, with the effect that product quality, productivity and process reliability are assured of the highest sustainable level.
MAY 06, By S B Parikh. THE concept of sending the goods outside the factory for job work is not new. However, exemption from Service Tax is available under Notification No. In other words, the value addition made by job worker either suffers Service Tax or Central Excise duty, as the case may be.
Читайте! - Джабба обливался. - В чем разница. Должна же она .