Title of Invention	A PROCESS FOR PRODUCING A HONEYCOMB BODY WITH METALLIC FLEECE
Abstract	A process for producing a honeycomb body (1) with at least one fleece (2) having metallic fibers (3), which comprises at least the following steps: a) producing metallic fibers (3); b) forming a layer (4) comprising metallic fibers (3); c) welding the metallic fibers (3) to one another; d) deforming the layer (4) to form a fleece (2) having defined fleece properties; e) producing a honeycomb body (1); f) brazing the honeycomb body (1). A honeycomb body produced in this way is suitable in particular for filtering exhaust gases from a motor vehicle.

Title of Invention

A PROCESS FOR PRODUCING A HONEYCOMB BODY WITH METALLIC FLEECE

Abstract

A process for producing a honeycomb body (1) with at least one fleece (2) having metallic fibers (3), which comprises at least the following steps: a) producing metallic fibers (3); b) forming a layer (4) comprising metallic fibers (3); c) welding the metallic fibers (3) to one another; d) deforming the layer (4) to form a fleece (2) having defined fleece properties; e) producing a honeycomb body (1); f) brazing the honeycomb body (1). A honeycomb body produced in this way is suitable in particular for filtering exhaust gases from a motor vehicle.

Full Text	Honeycomb body production with a metallic fleece The present invention relates to a process for producing a honeycomb body with at least one fleece having metallic fibers, and to corresponding honeycomb bodies and their use. Honeycomb bodies of this type may perform various functions in exhaust systems of internal combustion engines. By way of example, they are used as catalyst support bodies, as what are known as adsorbers, as filters, flow mixers and/or mufflers. The honeycomb body is usually distinguished by a favorable ratio of surface area to volume, i.e. it has a relatively large surface area and therefore ensures intensive contact with a gas stream flowing along or through it. Honeycomb bodies of this type are usually constructed with a plurality of different components (metal sheets, mats, tubes, etc.) in some cases comprising different materials (steel materials, ceramic substances, mixed materials, etc.) . In view of the high thermal and dynamic stresses in exhaust systems of mobile internal combustion engines, these individual components have to be permanently connected to one another. Various connection techniques are known for this purpose, for example brazing and/or welding. With regard to the connection techniques, it is necessary to bear in mind that they need to be suitable for medium-sized series production. In this context, cost aspects also play an important role, for example cycle rates, connection quality, process reliability, etc. Known processes for forming connections by joining techniques require an additional material, such as for example solder or welding filler. It is in this context particularly important for the additional material to be applied accurately at the location at which a connection is subsequently to be generated. Moreover, it should be noted that increasingly thin-walled - 2 - materials are to be used, since they can very quickly adapt to the temperature of the exhaust gas and accordingly react in a very dynamic way. Particularly when producing honeycomb bodies for filtering an exhaust-gas stream and/or for at least temporarily retaining solids contained in the exhaust gas, such as particulates, ash, soot and the like, ceramic and metallic filter materials have already been tested. As explained above, in view of the fluctuating thermal stresses acting on a honeycomb body of this type, it should be ensured that the thermal expansion properties of the components of the honeycomb body do not differ excessively from one another. This fact together with improved processibility have in very recent times led to increased use of metallic filter materials. These are formed with a gas-permeable, in particular porous fiber layer; in this context, the term fiber is to be considered a generic term encompassing in particular also wires, chips and the like. The production of metal filter media of this type and their integration into the production processes for a honeycomb body accordingly constitutes a particular manufacturing technology requirement. The metallic filter materials need to be adapted to the intended uses of the honeycomb body thereby formed, requiring a high degree of flexibility in terms of the manufacturing steps. It is an object of the present invention to at least partially alleviate the technical problems which have been outlined in connection with the current state of the art. In particular, it is necessary to specify a process for producing a honeycomb body which can be carried out reliably even as part of series production. Moreover, it is intended to improve the ability to recycle honeycomb bodies of this type by using metallic fibers and reusing them. The honeycomb bodies produced by the process, within series production, should have - 3 - only minor deviations in terms of functionality and service life. It is also intended to specify specially configured honeycomb bodies and preferred application areas for these honeycomb bodies. These objects are achieved by the process for producing a honeycomb body with at least one fleece having metallic fibers corresponding to the features of patent claim 1. Further advantageous configurations of the invention are given in the dependent patent claims. It should be noted that the features listed individually in the patent claims can be combined with one another in any technologically appropriate way in order thereby to describe further configurations of the process according to the invention. The process according to the invention for producing a honeycomb body with at least one fleece having metallic fibers comprises at least the following steps: a) producing metallic fibers; b) forming a layer comprising metallic fibers; c) welding the metallic fibers to one another; d) deforming the layer to form a fleece having defined fleece properties; e) producing a honeycomb body; f) brazing the honeycomb body. The individual steps and their configurations in detail are explained in more detail below, including with reference to the particularly preferred configurations. The word "fiber" serves in particular to describe an elongate element and in particular also encompasses elements in wire form, in chip form and the like. The metallic fibers may be substantially round, oval or polygonal in form. Fibers with a flat cross section are particularly preferred. The metallic fibers comprise in particular a material which substantially comprises steel as base material, with high chromium (e.g. in a - 4 - range from 18 to 21% by weight) and/or aluminum contents (e.g. at least 4.5% by weight, in particular at least 5.5% by weight), preferably being provided. The metallic fibers are preferably designed with a fiber length in the range from 0.1 to 50 mm (in particular in a range from 1 to 10 mm) and a fiber diameter in the range from 0.01 to 0.1 mm (in particular in a range from 0.02 to 0.05 mm). In this context, it should in principle be mentioned at this point that with regard to configuring the process for series operation, the process steps should take place as continuously as possible, in which context steps b), c) and/or d) should preferably be carried out at a rate of advance of at least 3 meters per minute (m/min), preferably at least 5 m/min or even 10 m/min. With regard to step e), under certain circumstances separate assembly operations may be necessary, requiring discontinuous operation, but these should nonetheless be carried out at correspondingly high cycle rates. Step f) ensures that the individual components of the honeycomb body are arranged captively with respect to one another, so that the honeycomb body is able to withstand the high thermal and dynamic stresses in the exhaust system of mobile internal combustion engines. With regard to the production of metallic fibers, it is particularly advantageous for step a) to comprise at least one of the following production methods: a.1) separating from a metal block; a.2) continuous fiber production from a metal melt; a.3) discontinuous removal from a metal melt. The "separation" from a metal block in accordance with method a.1) comprises in particular also milling, drilling, turning, planing, rasping, cutting or similar, in particular chip-producing, manufacturing - 5 - processes. The chip in this case constitutes the fiber. Whereas a broken chip is formed at regular intervals during milling, planing and rasping, turning or drilling can also produce very long chips. A metal block is to be understood in particular as meaning a solid body made from metal; the specific configuration of the body is to be selected on the basis of the production process used for producing the chips or fibers. Accordingly, the metal block may be in the form of a cylinder, a cuboid, a wire or in similar form. In the case of continuous fiber production (cf. method a.2)), a wire-like, very long or so-called "endless" fiber is produced from the metal melt. In this case, the fibers can be drawn or extruded individually or as a combined set. For clarification of this production method, the person skilled in the art can refer, for example, to corresponding descriptions on the production of wires. The discontinuous removal of the fibers from a metal melt (cf. method a.3)) represents, as it were, a mixed method somewhere between methods a.1) and a.2) . By way of example, a rotor with a structured circumferential surface is moved relative to the metal melt, with parts of the metal melt being removed from the bath as a result of temporary contact and these parts of the metal melt subsequently cooling to form the metallic fibers. In this case, fibers are produced repeatedly and discontinuously at a high speed. It is particularly advantageous if during step a) at least from time to time measures are taken to avoid an oxide layer on the fibers. This applies in particular to production method a.1), since in this case very high temperatures may under certain circumstances occur during production of the fibers. An oxide layer on the surface of the fibers can impede subsequent processing steps and/or endanger their reliable execution. - 6 - Therefore, it is proposed at this point, by way of example, that a cooled atmosphere and/or an atmosphere with a reducing action be provided continuously and/or intermittently. By way of example, coolant and/or a shielding gas comprising argon and/or helium can be supplied during separation of the fibers from a metal block. Both measures, as well as other known measures, serve to avoid the formation of an oxide layer. In addition, the fibers can also be remachined, so that an oxide layer located on the surface of the fiber is mechanically or abrasively removed. The term "avoid" is also understood to encompass reduced formation (reduction) of oxide layers compared to normal conditions. Furthermore, it is proposed that between step a) and step b) at least the step ab) of fiber preparation is also carried out, comprising at least one of the following operations: ab.1) classifying the fibers; ab.2) selecting the fibers; ab.3) returning the fibers for reuse; ab.4) cutting the fibers; ab.5) mixing the fibers; ab.6) cleaning the fibers. Fiber preparation constitutes an important working step with a view to the production of honeycomb bodies with targeted, different properties in a production line. In this case, the fibers produced continuously or discontinuously can be inspected for their intended use and predestined accordingly. In the context of fiber preparation, it is intended in particular to compensate for inhomogeneities in the fiber form caused by the process used to produce the fibers. The "classifying" of the fibers comprises in particular recognizing and allocating the fibers to predetermined classes which depend, for example, on the weight, lay, - 7 - thickness, shape or another parameter of the fibers. Here, in particular with a view to production methods a.1) and a.3), in which the chip shape may under certain circumstances vary, it is proposed that three different classes be provided, into which the fibers produced are classified. Furthermore, it is also possible to define exclusion criteria, in which case the fibers which meet the exclusion criteria are to be assigned to a further class. It is also possible for sensors to be used for the classification itself, in which case, by way of example, the chip shape, length and the like is recorded by means of at least one optical sensor. Furthermore, fans, fluids, sieves, etc. can also be used to recognize or classify the fibers. During the selection of the fibers, the (preferably previously classified) fibers are separated from one another. Fans, fluids, sieves, etc. can also be used for this purpose. If the fibers have been classified into three classes, the fibers from two classes, for example, can be fed for further processing, where the fibers in the third class are fed back to the production method as raw material (scrap). After the selecting of the fibers, the fibers which have been separated from one another are separately treated further at least for one subsequent step of the production process. As has already been indicated above, the classifying or selecting of the fibers in a simple way also allows returning of the fibers for reuse. This is advantageous with a view to exploitation of raw materials and the environment. The returned fibers can, for example, be melted down again and fed back to the production methods listed above in the form of a metal melt or metal block. In this case, cleaning treatments and/or heat treatments may be provided in between. The "endless" fibers in particular from the fiber - 8 - production method corresponding to step a.2) can now be cut to a predetermined length. The cutting of the fibers can be carried out so as to produce a constant and/or varying fiber length. In particular in the case of a varying fiber length, this process step can also be followed by classifying and/or selecting. Furthermore, the fibers may also be mixed. This allows, for example, a defined spatial orientation of the fibers to be generated with respect to one another; however, it is also possible for the fibers which are being produced to be mixed with further fibers (for example of a different material and/or a different form). It is also possible to produce a layered arrangement of the fibers of different configuration as early as at this stage; however, a random layer of the fibers is ultimately preferred. Finally, it may also be advantageous for the fibers produced to be cleaned. This also allows the removal of impurities (soot, oil, etc.), for example including an oxide layer. Cleaning with a fluid is particularly advantageous, in which case differently shaped fibers are also classified and/or selected, if appropriate directly, as a result of different immersion properties. Furthermore, it is proposed here that step b) comprises at least one of the following operations: b.1) distributing fibers on a base; b.2) adding at least one additive; b.3) determining at least one layer parameter; b.4) altering the at least one layer parameter; b.5) continuously moving the layer. It is preferable for a distributor, a vibrator and/or a sieve to be used to distribute the fibers on a base. These appliances are suitable for effecting a large- area or uniform distribution of the fibers on the base. - 9 - In particular in the configuration of the production process, comprising steps ab.1) and/or ab.2), it is also possible to provide a plurality of these appliances, each adding one class of the fibers to the base (in a temporally and/or spatially offset manner). This also allows, for example, the formation of layers of different fibers on the base. Accordingly, the distribution of the fibers, in addition to the layered configuration, can also be configured with a gradient, i.e. with a substantially continuous profile of a fiber property from the underside of the fiber layer to the topside of the fiber layer, or as a random layer, in which the fibers are placed in unordered fashion with respect to one another. With regard to the addition of an additive, by way of example it is also possible to add further, metallic filter materials. By way of example, additives of this type comprise metallic powders, sintering materials, fabrics, etc. The additive therefore in particular also serves to build up the fiber fleece. During and/or after step b) , it is advantageous to determine at least one layer parameter. This gives monitoring of the layer formation, the layer being compared, for example, on the basis of a predetermined porosity, a predetermined weight per unit area, a predetermined light reflectivity, a predetermined flow resistance, etc. The layer parameter can be monitored continuously, and when a defined value is reached can lead either to interruption of a process step taking place at the same time or to activation of a further process step. If appropriate, means are also provided which allow the determined layer parameter or the layer parameter which is to be determined to be altered. Accordingly, by way of example it is possible to supply further fibers, additives, etc., the layer can be compacted, the - 10 - orientation of the fibers in the layer can be varied. With a view to the preferred configuration of the process for producing a honeycomb body as a continuous process, it is proposed that while a layer is being formed, the layer be moved continuously. In this case, the base on which the fibers are distributed is advantageously designed as a conveyor belt. Layer parameters can also be adjusted by varying, for example, the conveying rate. At the same time, a conveyor belt of this type may have means for determining at least one layer parameter. To prevent the layer of fibers from breaking up during the movement, it is also possible for the conveyor belt to be assigned means which temporarily fix the position of the fibers with respect to one another (such as for example magnetic fields). According to a further configuration of the process, step c) comprises at least one of the following operations: c.1) carrying out resistance welding at least once; c.2) carrying out roller seam welding at least once; c.3) welding under shielding gas; c.4) compacting the layer; c.5) inspecting the welded joins. Although in principle other ways of fixing the fibers to one another are known (sintering, mechanical interlocking, etc.), welding is proposed as the preferred joining technique in the present context. On account of the fleece being configured with metallic fibers, resistance welding is suggested, since this can be carried out continuously at a relatively high speed. Roller seam welding as well as projection welding processes belong to the class of pressure connection welding processes, in particular resistance pressure welding. In resistance welding, the heating at the - 11 - welding location takes place as a result of Joule resistance heating when current flows through an electrical conductor. The current is supplied via electrodes with a convex or planar working surface. For roller seam welding, two (driven) electrodes in roller form or the like are used. The fibers to be welded in the layer are in this case arranged predominantly overlapping and in contact with one another. The layer comprising the fibers is then passed through the electrodes, which are at least partially pressed together. Depending on the form of contact, current flows from one electrode through the fibers to the opposite electrode, where weld spots are formed. To process the largest possible areas of the layer with a welding installation of this type, it is necessary to ensure that a large number of welded joins are generated as uniformly as possible over the entire region. To accomplish a welded join of this nature, it may under certain circumstances even be necessary for a plurality of welding installations in succession to be used to form the desired welded joins. In this case, the layer is preferably fed continuously firstly through a first welding installation and then a second welding installation, these welding installations being adapted to one another in such a way that new welded connections are generated on the second passage. With regard to steps c.1) and c.2), it should additionally also be noted that these can be combined with further processes for forming connections by joining techniques; by way of example, the fibers can be previously woven or then also sintered together. On account of the high, albeit spatially very restricted, introduction of heat into the metallic layer, there is once again a risk of oxide formation on the fibers, and consequently it is advantageous for the welding of the fibers to one another to be carried out - 12 - under shielding gas. The shielding gas preferably comprises at least one of the components argon and helium. The layer can be compacted immediately before, during and/or after welding. The compacting of the layer can, for example, take place in such a manner that the layer is passed through two rollers, between which there is a gap, the gap being smaller than the layer thickness. During the compacting of the layer, it is preferable for the cavities or pores formed therein to be reduced in size, with the fibers also being plastically deformed. It is in this way also possible to achieve a stronger bond between the fibers. If compacting is to take place during the welding process, the welding process is preferably configured as a pressure welding process. Under certain circumstances, the layer can also be compacted again, for example, when it is directly subjected to a second welding process. After the welding operation, it is also possible to inspect the welded connections. In this context, an optical analysis of the moving fiber layer, a targeted deformation of the fiber layer or also a flow resistance of the fiber layer can be recorded. During bending, for example by deformation about a shaft, the bending forces can be used as a measure of the quality of the welded connection. It is also possible for the welded layer to be exposed to an air stream flowing through it, in which case conclusions as to the welded connections can be drawn from the deformation of the layer, the number of fibers which become detached, etc. In this case, a controlled welding process is preferred, which therefore opens up the possibility of adapting the welding process if inadequate welded connections are established. According to a further configuration of the process according to the invention, step d) comprises at least - 13 - one of the following operations: d.1) compacting the layer; d.2) separating a plurality of fleeces from the layer; d.3) classifying the fleeces; d.4) winding, twisting or folding a fleece; d.5) structuring a fleece; d.6) stamping out regions of a fleece; d.7) combining a fleece with closure elements; d.8) seaming the layer. The "compacting" of the layer can be used to set the desired fleece properties (e.g. density, porosity, strength, thickness, etc.). A "fleece" is to be understood in particular as meaning a sheet-like structure which is formed with predetermined "final" dimensions and in which the fibers are arranged randomly or in ordered fashion with respect to one another. Examples of fleeces include woven fabrics, mesh structures, knitted fabrics, random layers, etc. The fleece is in this case preferably formed with fibers which are made from a corrosion-resistant material which is able to withstand high temperatures; this is also intended to apply to all the other additives of the fleece. The porosity of the fleece produced is preferably in a range from 30% to 80%, in particular in a range from 45% to 60%. The fleece has a preferred weight per unit area in the range from 250 to 1500 g/m2 [grams per square meter]. The separation of a plurality of fleeces (d.2)) from the layer substantially takes place in a direction which is transverse to the conveying direction of the layer; in this context, it is possible to use stamping tools, blades which move with the layer, i.e. what are known as flying blades, or similar appliances. In particular in the case of production with different fleece properties, i.e. a process variant in which only - 14 - a certain number of fleeces are produced with one fiber fleece property, and then at least one further number is produced with different fiber fleece properties, it is advantageous for the fleeces to be classified accordingly (d.3)). Then, the different fleeces can also be fed separately to further processing stations. It is also possible to identify scrap parts during the classification and to return these scrap parts for reuse if appropriate. Whereas hitherto the fleeces were configured as substantially sheet-like structures located substantially in one plane, it is now also possible for the fleeces to be wound and/or twisted and/or stacked and/or folded after operation d.4) . This is to be understood as meaning in particular that the fleece acquires a curvature through plastic deformation. Following this plastic deformation, the fleece can, for example, be bent in an S shape, wound up helically, folded in a star shape, folded in bellows-like fashion, etc. The deformation of the fleece may also take place together with further elements of the honeycomb body (sheet-metal foils, supporting structures, etc.). In addition to the large-area deformation of the fleece, there is also the possibility of structuring the fleece (d.5)). During the structuring, a structure no larger than the fleece thickness is introduced into the fleece. Suitable structures are in particular corrugated structures, zigzag structures and/or rectangular structures. These structures subsequently at least partially delimit flow passages of a honeycomb body. To produce a structure of this type, it is possible, for example, to use intermeshing corrugated rollers through which the fleece is guided. According to step d.6) , it is also possible to stamp out regions of a fleece. It is in this case possible, for example, to generate openings which, although - 15 - significantly larger than the pores or cavities in the interior of the fleece, if appropriate also do not exceed a maximum extent of 20 mm. Openings of this type can be used, for example, to set defined part-flows in the interior of the honeycomb body, to form a bypass or to produce swirling locations in the honeycomb structure. Furthermore, however, it is also possible for a very large region of the fleece to be stamped out, in which case these, for example, disk-shaped fleeces (if appropriate with a diameter of greater than 70 mm, in particular at least 90 mm) can then themselves in turn be used as filter medium, for example in a radial-flow honeycomb body. Of course, a plurality of stamping operations or types of stamping can be carried out simultaneously. Finally, the fleece can also be combined with closure elements (d.7)). These are preferably arranged close to an edge of the fleece and for example have a sealing function with respect to the honeycomb body and/or serve for attaching further fleeces and/or housing parts. The closure element used may, for example, be a cord, a sheet-metal strip, an element comprising sinter material, a perforated mask, etc. According to d.8), seaming of the layer is also proposed. This is to be understood in particular as meaning that the edges of the layer which run in the direction of extent of the layer run substantially parallel, and/or a desired width of the layer is maintained. This can be realized, for example, by removing fibers, with the layer preferably being cut to size. According to a further configuration of the process, step e) comprises at least one of the following operations: e.1) combining at least one fleece with at least one element selected from the group consisting of: - 16 - at least one metal foil, at least one housing, at least one electrode, at least one honeycomb structure, at least one perforated tube; e.2) applying glue to at least one fleece or an element connected to it; e.3) applying solder to at least one fleece or an element connected to it. The metal foil is preferably a foil with a thickness of less than 0.15 mm, in particular in the range from 0.03 mm to 0.12 mm. The metal foil comprises chromium and aluminum and is based on a steel material which is thermally stable and corrosion-resistant. The metal foil preferably has a corrugated structure. The housing is preferably likewise metallic and in addition to round, oval or polygonal cross sections, may also have any other desired cross section. The housing at least partially accommodates the fleece and/or the metal foil in its interior. The provision of an electrode is recommended in particular if the honeycomb body is to be designed to be electrically heatable. For this purpose, the honeycomb body may also be assigned insulation layers which partially form a defined flow path through the honeycomb body. When a voltage is applied, the fleece and/or metal foil is heated up in a controllable way on account of Joule resistance heating. The heating of the honeycomb body may be advantageous, for example, during the cold-start phase of the exhaust system and/or for the thermal regeneration of a honeycomb body used as a particulate trap. Furthermore, by way of example it is also possible for the honeycomb body together with a further honeycomb structure to be positioned in a single housing. The honeycomb structure can fundamentally be formed using metal foils or (extruded) ceramic material. If a radial-flow honeycomb body is to be produced, by way of example it is possible for fleeces which have been stamped out in disk shapes to be arranged at defined intervals around at least one - 17 - perforated tube or within a perforated tube, allowing the gas stream to flow through from regions located on the inner side to regions located on the radially outer side. At the same time as or at a different time than the combining of the at least one fleece with at least one element selected from the group, it is also possible for the fleece and/or an element which is to be connected to it to be at least partially covered with glue. The application of glue (bonding agent, adhesive, etc.) can be carried out by means of strip material, self-adhesive stickers, a printing process, etc. Likewise at the same time as and/or after the combining operation in accordance with step e.1), it is possible for solder to be applied to at least part of at least one fleece and/or an element connected to it. The solder material can likewise be applied in the form of strip material, stickers and/or by a printing process. However, it is also possible for a solder in powder form, which sticks to the subregions which have previously been provided with glue, to be fed to the honeycomb body. With regard to the techniques used to apply glue and solder to a honeycomb structure, reference is made in particular to the methods which are already known, in particular in the name of the Applicant, which can be used in full for further details. Finally, the invention also proposes a honeycomb body having at least one fleece produced by a process of the type described above in accordance with the invention, the honeycomb body being designed with passages which are closed on alternate sides, and the at least one fleece having at least one fleece property which is designed to be different over the thickness of the fleece. In principle, the honeycomb bodies can be produced with a large number of configurations in - 18 - accordance with the above-described process, for example in the manner of a radial-flow honeycomb body, with passages arranged in a star shape, with passages in the form of a ring or a bellows or as an open particulate trap in which none of the filter passages is completely closed. However, in particular with a view to a honeycomb body being used in the exhaust system of mobile internal combustion engines (spark- ignition and diesel engines) with a very high purifying action with regard to the particulates contained in the exhaust gas, the invention here proposes a honeycomb body which has passages that are closed on alternate sides. For this purpose, the honeycomb body is designed with at least one closure element at the end sides, so that (preferably) all the passages are closed either at one end side or the other. This has the effect, for example, of ensuring that the entire exhaust-gas stream has to flow through a metallic fleece at least once. In this context, it is proposed here that a fleece property be designed to be different over the thickness of the fleece, for example the porosity, the type of fibers, the provision of additives, etc. Under certain circumstances, it may also be advantageous for this and/or another fleece property to vary perpendicular to the fleece thickness, i.e. for example in the axial direction of the honeycomb body. The combination of a passage system which is closed on alternate sides and the differently configured fleece property has the advantage that the flow through the closure elements is diverted in defined directions through the fleece in a manner which can be accurately predicted. The fleece can now be adapted to these flow properties of the exhaust gas, so that, for example, particulates of different sizes are absorbed or accumulated in different regions of the fleece. This targeted absorption or accumulation of particulates can promote efficient conversion of these pollutants, for example by the provision of a catalyst in the vicinity. It is - 19 - preferable for a honeycomb body of this type to be formed with a combination of at least one fleece and at least one corrugated metal foil. It is preferable for the honeycomb body described above to be used for filtering an exhaust-gas stream. A particular application area which should be mentioned is the automobile industry, in which case this honeycomb body may form part of a more complex exhaust system, in which the honeycomb body is combined with at least one catalytic converter, an adsorber, an SCR catalyst, a particulate trap, etc. The invention and the technical background are described in more detail below with reference to the figures. The figures also show particularly preferred configurations of the invention, although without the invention being restricted to these configurations. It should be noted that the illustrations in the figures are purely schematic in nature and are not generally suitable for illustrating size ratios. In the drawings: Fig. 1 diagrammatically depicts a variant embodiment of a process for producing a honeycomb body with at least one fleece having metallic fibers; Fig. 2 shows a honeycomb body which is closed on alternate sides; Fig. 3 shows a radial-flow honeycomb body; Fig. 4 shows an electrically heatable exhaust-gas treatment unit with a honeycomb body; Fig. 5 shows a fleece having metallic fibers, and Fig. 6 diagrammatically depicts a further variant embodiment of a process for producing a - 20 - honeycomb body. Fig. 1 illustrates a variant embodiment of the process for producing a honeycomb body, the figure schematically indicating, on the left-hand side, the process steps referred to by their short designations here, while the right-hand side of the figure illustrates an example of a configuration of this process step. Accordingly, first of all, according to step a. 3), discontinuous removal from a metal melt 15 is carried out to produce metallic fibers 3. In this case, a rotor 16 which rotates within the metal melt 15 generates fibers 3 which to set are fed to a tray 33. The fibers 3 produced in this way are then classified in accordance with step ab.l). For this purpose the fibers 3 are fed to a sorter 17 which simultaneously also effects selection or separation of the different fibers 3, for example as a function of the shape and/or size of the fibers 3. These fibers are then fed to a distributor 18 which layers the fibers uniformly on a base 5 to form a layer 4 (cf. step b.1)). The base 5 is in this case designed as a conveyor belt, so that the layer 4 which is generated can then be fed to a welding process. After step c.2), the layer 4 is passed through a welding installation 19, which is suitable for carrying out a roller seam welding operation at least once. After this, in accordance with step d.2), the layer 4 is converted into separate fleeces 2 of a predetermined fleece thickness 14 and fleece length 22, which is done by separating the fleeces 2 by means of a separation apparatus 20. - 21 - The fleeces 2 produced in this way are then combined with a plurality of corrugated metal foils 8 so as to form a honeycomb body 1 having a multiplicity of passages 13 (step e.1)). To form connections between the individual elements of the honeycomb body by a joining technique and/or to further develop the connections between the fibers made by a joining technique, the honeycomb body 1 is then also subjected to a brazing process (step f)) , the honeycomb body 1 being fed at least from time to time and preferably continuously to a furnace 21, in which a vacuum and temperatures above 1000°C preferably prevail. The honeycomb body 1 produced in this way is particularly suitable for use in the exhaust system of automobiles. Fig. 2 shows a possible variant embodiment of a honeycomb body 1 produced by the process according to the invention. The honeycomb body 1 once again has a multiplicity of passages 13, which in this case are closed off on alternate sides by means of closure elements 7 which are each secured to one end side 23. In this way, the exhaust gas is forced first of all to enter an open passage 13 in the direction of flow 24, but then, on account of the closure element 7, to flow through the fleece 2 and pass into another, adjacent passage 13. During passage through the fleece 2, in particular particulates (such as soot and ash) are retained. To prevent passages 13 becoming unusable on account of soot accumulating over an excessive area, regions 6 are stamped out of the fleece 2, so as to form a type of "bypass". The honeycomb body 1 is surrounded by a metallic housing 9. Fig. 3 illustrates a further configuration of a honeycomb body 1 as can be produced by the process. This honeycomb body 1 has a star-shaped structure and medium flows radially through it from the inside - 22 - outward. For this purpose, the exhaust gas passes through a tube 12, which is provided with a perforation in the region of the honeycomb body 1. As a result, the exhaust gas passes into the pockets 25 which are formed by the fleece 2 and form the passages 13. The exhaust gas emerges through these pockets 25 substantially radially with respect to the axis 26 and on the outer side is discharged again in a substantially axial direction. Fig. 4 illustrates an exhaust-gas treatment unit 34 which is designed as an electrically heatable honeycomb body 1. The honeycomb body 1 itself is once again formed with a combination of metallic fleece 2 and metal foils 8, in such a way as to form (open) passages 13 which run substantially parallel to one another. Even if the passages 13 are mostly not completely closed, the metal foils 8 do have flow-influencing means 29 which at least partially project into the passages 13 and are responsible for diverting parts of the exhaust-gas streams through the fleece 2. This honeycomb body 1 is arranged in a housing 9. A further honeycomb structure 11, which may be configured for example as an oxidation catalyst, is provided at the end side of the honeycomb body 1. The honeycomb structure 11 is connected to the honeycomb body 1 by means of (at least partially electrically insulated) pins 27. The contact-connection of the honeycomb structure 11 for a flow of electric current is effected by means of the electrodes 10 which are diagrammatically depicted. It is therefore possible for the exhaust gas which comes into contact with the honeycomb structure 11 first of all as seen in the direction of flow 24 to be heated up and in the process, for example, also allowing thermal regeneration of the downstream particulate trap comprising the honeycomb body 1. The entire arrangement of the honeycomb body 1 with the combination of the - 23 - honeycomb structure 11 is integrated in the exhaust pipe 28, for example of a motor vehicle. Fig. 5 now illustrates in detail one configuration of the fleece 2, which comprises a multiplicity of metallic fibers 3. The fibers 3 are arranged as a random layer and are connected to one another in separate connection zones 30. The connection zones 30 are designed at a spacing 31 and with a width 32 which are substantially characterized by the execution of, for example, the roller seam welding. It should be noted here that under certain circumstances the width 32 may also be designed to be greater than the spacing 31. It can be seen from Fig. 5 that the fleece 2 is a substantially sheet-like structure, the smallest dimension generally being the fleece thickness 14. The formation of the connection zones 30 can also serve to realize an anisotropic formation of at least one fiber fleece property. In addition to the connection zones 3 0 illustrated here, it is possible to generate further connections by a joining technique between the fibers 3, for example sintered connections which are produced during process step f) . Fig. 6 diagrammatically depicts a further variant embodiment of the process for producing a honeycomb body 1 through to production of the fleeces 2. To complete the honeycomb body 1, reference may be made to joining methods described above. The fiber production in this case uses a cutting installation 35 which is supplied with a plurality of metallic wires 36. The cutting installation 35 has a cutting mechanism which cuts the long wires 36 into short fibers 3 in a controlled way. The fibers 2 produced in this way are classified and selected in a sorter 17 before then being fed to different distributors 18. A layer 4 is produced in two stations, four distributors 18 being arranged above a base 5 configured as a conveyor belt within a first station, illustrated on the left, and - 24 - this conveyor belt then checks the layer 4 produced for its fleece property by means of a balance 37, and the fleece is then filled in a targeted way with the established quantity of fibers 3 that is still required if appropriate in a second station comprising a further distributor 18. Once the desired weight per unit area of the layer 4 is present, the latter is fed to a first deformation installation 38 in the conveying direction 40. There, the layer 4 is compacted and the edges of the layer 4 are precut. The fiber material which is separated off during the precutting, preferably amounting to less than 10% of the fiber material used, is returned to the first station or at least one of the distributors 18 or the sorter 17. The pretreated layer 4 then passes through a welding installation 19 which is suitable for carrying out roller seam welding at a welding rate of at least 4 m/min for a layer width in the range of over 100 mm. After the fibers 3 have been captively joined to one another, the layer finally passes through a further deformation installation 38, in which further compacting is carried out and separate fleeces 2 with predetermined dimensions are separated. These fleeces 2 can then be fed to further processing stations to form a honeycomb body 1. The method illustrated here for producing the fleeces 2 is suitable in particular for series production, since high conveying and welding rates can be realized and at the same time a controlled addition of fibers to produce desired fleece properties is possible. The proposed processes are suitable in particular for the series production of particulate traps for exhaust systems of automobiles. - 25 - List of designations 1 Honeycomb body 2 Fleece 3 Fiber 4 Layer 5 Base 6 Region 7 Closure element 8 Metal foil 9 Housing 10 Electrode 11 Honeycomb structure 12 Tube 13 Passage 14 Fleece thickness 15 Metal melt 16 Rotor 17 Sorter 18 Distributor 19 Welding installation 20 Separation apparatus 21 Furnace 22 Fleece length 23 End side 24 Direction of flow 25 Pocket 26 Axis 27 Pin 28 Exhaust pipe 29 Flow-influencing means 30 Connection zone 31 Spacing 32 Width 33 Tray 34 Exhaust-gas treatment unit 35 Cutting installation 36 Wire 3 7 Balance - 26 - 38 Deformation installation 39 Fiber return 40 Conveying direction - 27 - Patent Claims 1. A process for producing a honeycomb body (1) with at least one fleece (2) having metallic fibers (3) , which comprises at least the following steps: a) producing metallic fibers (3) ; b) forming a layer (4) comprising metallic fibers (3); c) welding the metallic fibers (3) to one another; d) deforming the layer (4) to form a fleece (2) having defined fleece properties; e) producing a honeycomb body (1); f) brazing the honeycomb body (1). 2. The process as claimed in claim 1, in which step a) comprises at least one of the following production methods: a.1) separating from a metal block; a.2) continuous fiber production from a metal melt (15) ; a.3) discontinuous removal from a metal melt (15) . 3. The process as claimed in claim 1 or 2, in which during step a) at least from time to time measures are taken to avoid an oxide layer on the fibers (3) . 4. The process as claimed in one of the preceding claims, in which between step a) and step b) at least the step ab) of fiber preparation is also carried out, comprising at least one of the following operations: ab.1) classifying the fibers (3); ab.2) selecting the fibers (3); ab.3) returning the fibers (3) for reuse; ab.4) cutting the fibers (3) ; ab.5) mixing the fibers (3); ab.6) cleaning the fibers (3) . 5. The process as claimed in one of the preceding claims, in which step b) comprises at least one of the - 28 - following operations: b.1) distributing fibers (3) on a base (5); b.2) adding at least one additive; b.3) determining at least one layer parameter; b.4) altering the at least one layer parameter; b.5) continuously moving the layer (4). 6. The process as claimed in one of the preceding claims, in which step c) comprises at least one of the following operations: c.1) carrying out resistance welding at least once; c.2) carrying out roller seam welding at least once; c.3) welding under shielding gas; c.4) compacting the layer (4); c.5) inspecting the welded joins. 7. The process as claimed in one of the preceding claims, in which step d) comprises at least one of the following operations: d.1) compacting the layer (4); d.2) separating a plurality of fleeces (2) from the layer (4) ; d.3) classifying the fleeces (2); d.4) winding, twisting or folding a fleece (1); d.5) structuring a fleece (2); d.6) stamping out regions (6) of a fleece (2) ; d.7) combining a fleece (2) with at least one closure element (7); d.8) seaming the layer (4) . 8. The process as claimed in one of the preceding claims, in which step e) comprises at least one of the following operations: e.1) combining at least one fleece (2) with at least one element selected from the group consisting of: at least one metal foil (8) , at least one housing (9) , at least one electrode (10), at least one honeycomb structure (11) , at least one - 29 - perforated tube (12); e.2) applying glue to at least one fleece (2) or an element connected to it; e.3) applying solder to at least one fleece (2) or an element connected to it. 9. A honeycomb body (1) having at least one fleece (2) produced by the process as claimed in one of the preceding claims, the honeycomb body (1) being designed with passages (13) which are closed on alternate sides, and the at least one fleece (2) having at least one fleece property which is designed to be different over the thickness (14) of the fleece. 10. The use of the honeycomb body (1) as claimed in claim 9 for filtering an exhaust-gas stream. A process for producing a honeycomb body (1) with at least one fleece (2) having metallic fibers (3), which comprises at least the following steps: a) producing metallic fibers (3); b) forming a layer (4) comprising metallic fibers (3); c) welding the metallic fibers (3) to one another; d) deforming the layer (4) to form a fleece (2) having defined fleece properties; e) producing a honeycomb body (1); f) brazing the honeycomb body (1). A honeycomb body produced in this way is suitable in particular for filtering exhaust gases from a motor vehicle.

Full Text

Honeycomb body production with a metallic fleece
The present invention relates to a process for
producing a honeycomb body with at least one fleece
having metallic fibers, and to corresponding honeycomb
bodies and their use.
Honeycomb bodies of this type may perform various
functions in exhaust systems of internal combustion
engines. By way of example, they are used as catalyst
support bodies, as what are known as adsorbers, as
filters, flow mixers and/or mufflers. The honeycomb
body is usually distinguished by a favorable ratio of
surface area to volume, i.e. it has a relatively large
surface area and therefore ensures intensive contact
with a gas stream flowing along or through it.
Honeycomb bodies of this type are usually constructed
with a plurality of different components (metal sheets,
mats, tubes, etc.) in some cases comprising different
materials (steel materials, ceramic substances, mixed
materials, etc.) . In view of the high thermal and
dynamic stresses in exhaust systems of mobile internal
combustion engines, these individual components have to
be permanently connected to one another. Various
connection techniques are known for this purpose, for
example brazing and/or welding.
With regard to the connection techniques, it is
necessary to bear in mind that they need to be suitable
for medium-sized series production. In this context,
cost aspects also play an important role, for example
cycle rates, connection quality, process reliability,
etc. Known processes for forming connections by joining
techniques require an additional material, such as for
example solder or welding filler. It is in this context
particularly important for the additional material to
be applied accurately at the location at which a
connection is subsequently to be generated. Moreover,
it should be noted that increasingly thin-walled
- 2 -
materials are to be used, since they can very quickly
adapt to the temperature of the exhaust gas and
accordingly react in a very dynamic way.
Particularly when producing honeycomb bodies for
filtering an exhaust-gas stream and/or for at least
temporarily retaining solids contained in the exhaust
gas, such as particulates, ash, soot and the like,
ceramic and metallic filter materials have already been
tested. As explained above, in view of the fluctuating
thermal stresses acting on a honeycomb body of this
type, it should be ensured that the thermal expansion
properties of the components of the honeycomb body do
not differ excessively from one another. This fact
together with improved processibility have in very
recent times led to increased use of metallic filter
materials. These are formed with a gas-permeable, in
particular porous fiber layer; in this context, the
term fiber is to be considered a generic term
encompassing in particular also wires, chips and the
like. The production of metal filter media of this type
and their integration into the production processes for
a honeycomb body accordingly constitutes a particular
manufacturing technology requirement. The metallic
filter materials need to be adapted to the intended
uses of the honeycomb body thereby formed, requiring a
high degree of flexibility in terms of the
manufacturing steps.
It is an object of the present invention to at least
partially alleviate the technical problems which have
been outlined in connection with the current state of
the art. In particular, it is necessary to specify a
process for producing a honeycomb body which can be
carried out reliably even as part of series production.
Moreover, it is intended to improve the ability to
recycle honeycomb bodies of this type by using metallic
fibers and reusing them. The honeycomb bodies produced
by the process, within series production, should have
- 3 -
only minor deviations in terms of functionality and
service life. It is also intended to specify specially
configured honeycomb bodies and preferred application
areas for these honeycomb bodies.
These objects are achieved by the process for producing
a honeycomb body with at least one fleece having
metallic fibers corresponding to the features of patent
claim 1. Further advantageous configurations of the
invention are given in the dependent patent claims. It
should be noted that the features listed individually
in the patent claims can be combined with one another
in any technologically appropriate way in order thereby
to describe further configurations of the process
according to the invention.
The process according to the invention for producing a
honeycomb body with at least one fleece having metallic
fibers comprises at least the following steps:
a) producing metallic fibers;
b) forming a layer comprising metallic fibers;
c) welding the metallic fibers to one another;
d) deforming the layer to form a fleece having
defined fleece properties;
e) producing a honeycomb body;
f) brazing the honeycomb body.
The individual steps and their configurations in detail
are explained in more detail below, including with
reference to the particularly preferred configurations.
The word "fiber" serves in particular to describe an
elongate element and in particular also encompasses
elements in wire form, in chip form and the like. The
metallic fibers may be substantially round, oval or
polygonal in form. Fibers with a flat cross section are
particularly preferred. The metallic fibers comprise in
particular a material which substantially comprises
steel as base material, with high chromium (e.g. in a
- 4 -
range from 18 to 21% by weight) and/or aluminum
contents (e.g. at least 4.5% by weight, in particular
at least 5.5% by weight), preferably being provided.
The metallic fibers are preferably designed with a
fiber length in the range from 0.1 to 50 mm (in
particular in a range from 1 to 10 mm) and a fiber
diameter in the range from 0.01 to 0.1 mm (in
particular in a range from 0.02 to 0.05 mm).
In this context, it should in principle be mentioned at
this point that with regard to configuring the process
for series operation, the process steps should take
place as continuously as possible, in which context
steps b), c) and/or d) should preferably be carried out
at a rate of advance of at least 3 meters per minute
(m/min), preferably at least 5 m/min or even 10 m/min.
With regard to step e), under certain circumstances
separate assembly operations may be necessary,
requiring discontinuous operation, but these should
nonetheless be carried out at correspondingly high
cycle rates. Step f) ensures that the individual
components of the honeycomb body are arranged captively
with respect to one another, so that the honeycomb body
is able to withstand the high thermal and dynamic
stresses in the exhaust system of mobile internal
combustion engines.
With regard to the production of metallic fibers, it is
particularly advantageous for step a) to comprise at
least one of the following production methods:
a.1) separating from a metal block;
a.2) continuous fiber production from a metal melt;
a.3) discontinuous removal from a metal melt.
The "separation" from a metal block in accordance with
method a.1) comprises in particular also milling,
drilling, turning, planing, rasping, cutting or
similar, in particular chip-producing, manufacturing
- 5 -
processes. The chip in this case constitutes the fiber.
Whereas a broken chip is formed at regular intervals
during milling, planing and rasping, turning or
drilling can also produce very long chips. A metal
block is to be understood in particular as meaning a
solid body made from metal; the specific configuration
of the body is to be selected on the basis of the
production process used for producing the chips or
fibers. Accordingly, the metal block may be in the form
of a cylinder, a cuboid, a wire or in similar form.
In the case of continuous fiber production (cf. method
a.2)), a wire-like, very long or so-called "endless"
fiber is produced from the metal melt. In this case,
the fibers can be drawn or extruded individually or as
a combined set. For clarification of this production
method, the person skilled in the art can refer, for
example, to corresponding descriptions on the
production of wires.
The discontinuous removal of the fibers from a metal
melt (cf. method a.3)) represents, as it were, a mixed
method somewhere between methods a.1) and a.2) . By way
of example, a rotor with a structured circumferential
surface is moved relative to the metal melt, with parts
of the metal melt being removed from the bath as a
result of temporary contact and these parts of the
metal melt subsequently cooling to form the metallic
fibers. In this case, fibers are produced repeatedly
and discontinuously at a high speed.
It is particularly advantageous if during step a) at
least from time to time measures are taken to avoid an
oxide layer on the fibers. This applies in particular
to production method a.1), since in this case very high
temperatures may under certain circumstances occur
during production of the fibers. An oxide layer on the
surface of the fibers can impede subsequent processing
steps and/or endanger their reliable execution.
- 6 -
Therefore, it is proposed at this point, by way of
example, that a cooled atmosphere and/or an atmosphere
with a reducing action be provided continuously and/or
intermittently. By way of example, coolant and/or a
shielding gas comprising argon and/or helium can be
supplied during separation of the fibers from a metal
block. Both measures, as well as other known measures,
serve to avoid the formation of an oxide layer. In
addition, the fibers can also be remachined, so that an
oxide layer located on the surface of the fiber is
mechanically or abrasively removed. The term "avoid" is
also understood to encompass reduced formation
(reduction) of oxide layers compared to normal
conditions.
Furthermore, it is proposed that between step a) and
step b) at least the step ab) of fiber preparation is
also carried out, comprising at least one of the
following operations:
ab.1) classifying the fibers;
ab.2) selecting the fibers;
ab.3) returning the fibers for reuse;
ab.4) cutting the fibers;
ab.5) mixing the fibers;
ab.6) cleaning the fibers.
Fiber preparation constitutes an important working step
with a view to the production of honeycomb bodies with
targeted, different properties in a production line. In
this case, the fibers produced continuously or
discontinuously can be inspected for their intended use
and predestined accordingly. In the context of fiber
preparation, it is intended in particular to compensate
for inhomogeneities in the fiber form caused by the
process used to produce the fibers.
The "classifying" of the fibers comprises in particular
recognizing and allocating the fibers to predetermined
classes which depend, for example, on the weight, lay,
- 7 -
thickness, shape or another parameter of the fibers.
Here, in particular with a view to production methods
a.1) and a.3), in which the chip shape may under
certain circumstances vary, it is proposed that three
different classes be provided, into which the fibers
produced are classified. Furthermore, it is also
possible to define exclusion criteria, in which case
the fibers which meet the exclusion criteria are to be
assigned to a further class. It is also possible for
sensors to be used for the classification itself, in
which case, by way of example, the chip shape, length
and the like is recorded by means of at least one
optical sensor. Furthermore, fans, fluids, sieves, etc.
can also be used to recognize or classify the fibers.
During the selection of the fibers, the (preferably
previously classified) fibers are separated from one
another. Fans, fluids, sieves, etc. can also be used
for this purpose. If the fibers have been classified
into three classes, the fibers from two classes, for
example, can be fed for further processing, where the
fibers in the third class are fed back to the
production method as raw material (scrap). After the
selecting of the fibers, the fibers which have been
separated from one another are separately treated
further at least for one subsequent step of the
production process.
As has already been indicated above, the classifying or
selecting of the fibers in a simple way also allows
returning of the fibers for reuse. This is advantageous
with a view to exploitation of raw materials and the
environment. The returned fibers can, for example, be
melted down again and fed back to the production
methods listed above in the form of a metal melt or
metal block. In this case, cleaning treatments and/or
heat treatments may be provided in between.
The "endless" fibers in particular from the fiber
- 8 -
production method corresponding to step a.2) can now be
cut to a predetermined length. The cutting of the
fibers can be carried out so as to produce a constant
and/or varying fiber length. In particular in the case
of a varying fiber length, this process step can also
be followed by classifying and/or selecting.
Furthermore, the fibers may also be mixed. This allows,
for example, a defined spatial orientation of the
fibers to be generated with respect to one another;
however, it is also possible for the fibers which are
being produced to be mixed with further fibers (for
example of a different material and/or a different
form). It is also possible to produce a layered
arrangement of the fibers of different configuration as
early as at this stage; however, a random layer of the
fibers is ultimately preferred.
Finally, it may also be advantageous for the fibers
produced to be cleaned. This also allows the removal of
impurities (soot, oil, etc.), for example including an
oxide layer. Cleaning with a fluid is particularly
advantageous, in which case differently shaped fibers
are also classified and/or selected, if appropriate
directly, as a result of different immersion
properties.
Furthermore, it is proposed here that step b) comprises
at least one of the following operations:
b.1) distributing fibers on a base;
b.2) adding at least one additive;
b.3) determining at least one layer parameter;
b.4) altering the at least one layer parameter;
b.5) continuously moving the layer.
It is preferable for a distributor, a vibrator and/or a
sieve to be used to distribute the fibers on a base.
These appliances are suitable for effecting a large-
area or uniform distribution of the fibers on the base.
- 9 -
In particular in the configuration of the production
process, comprising steps ab.1) and/or ab.2), it is
also possible to provide a plurality of these
appliances, each adding one class of the fibers to the
base (in a temporally and/or spatially offset manner).
This also allows, for example, the formation of layers
of different fibers on the base. Accordingly, the
distribution of the fibers, in addition to the layered
configuration, can also be configured with a gradient,
i.e. with a substantially continuous profile of a fiber
property from the underside of the fiber layer to the
topside of the fiber layer, or as a random layer, in
which the fibers are placed in unordered fashion with
respect to one another.
With regard to the addition of an additive, by way of
example it is also possible to add further, metallic
filter materials. By way of example, additives of this
type comprise metallic powders, sintering materials,
fabrics, etc. The additive therefore in particular also
serves to build up the fiber fleece.
During and/or after step b) , it is advantageous to
determine at least one layer parameter. This gives
monitoring of the layer formation, the layer being
compared, for example, on the basis of a predetermined
porosity, a predetermined weight per unit area, a
predetermined light reflectivity, a predetermined flow
resistance, etc. The layer parameter can be monitored
continuously, and when a defined value is reached can
lead either to interruption of a process step taking
place at the same time or to activation of a further
process step.
If appropriate, means are also provided which allow the
determined layer parameter or the layer parameter which
is to be determined to be altered. Accordingly, by way
of example it is possible to supply further fibers,
additives, etc., the layer can be compacted, the
- 10 -
orientation of the fibers in the layer can be varied.
With a view to the preferred configuration of the
process for producing a honeycomb body as a continuous
process, it is proposed that while a layer is being
formed, the layer be moved continuously. In this case,
the base on which the fibers are distributed is
advantageously designed as a conveyor belt. Layer
parameters can also be adjusted by varying, for
example, the conveying rate. At the same time, a
conveyor belt of this type may have means for
determining at least one layer parameter. To prevent
the layer of fibers from breaking up during the
movement, it is also possible for the conveyor belt to
be assigned means which temporarily fix the position of
the fibers with respect to one another (such as for
example magnetic fields).
According to a further configuration of the process,
step c) comprises at least one of the following
operations:
c.1) carrying out resistance welding at least once;
c.2) carrying out roller seam welding at least once;
c.3) welding under shielding gas;
c.4) compacting the layer;
c.5) inspecting the welded joins.
Although in principle other ways of fixing the fibers
to one another are known (sintering, mechanical
interlocking, etc.), welding is proposed as the
preferred joining technique in the present context. On
account of the fleece being configured with metallic
fibers, resistance welding is suggested, since this can
be carried out continuously at a relatively high speed.
Roller seam welding as well as projection welding
processes belong to the class of pressure connection
welding processes, in particular resistance pressure
welding. In resistance welding, the heating at the
- 11 -
welding location takes place as a result of Joule
resistance heating when current flows through an
electrical conductor. The current is supplied via
electrodes with a convex or planar working surface. For
roller seam welding, two (driven) electrodes in roller
form or the like are used. The fibers to be welded in
the layer are in this case arranged predominantly
overlapping and in contact with one another. The layer
comprising the fibers is then passed through the
electrodes, which are at least partially pressed
together. Depending on the form of contact, current
flows from one electrode through the fibers to the
opposite electrode, where weld spots are formed. To
process the largest possible areas of the layer with a
welding installation of this type, it is necessary to
ensure that a large number of welded joins are
generated as uniformly as possible over the entire
region.
To accomplish a welded join of this nature, it may
under certain circumstances even be necessary for a
plurality of welding installations in succession to be
used to form the desired welded joins. In this case,
the layer is preferably fed continuously firstly
through a first welding installation and then a second
welding installation, these welding installations being
adapted to one another in such a way that new welded
connections are generated on the second passage. With
regard to steps c.1) and c.2), it should additionally
also be noted that these can be combined with further
processes for forming connections by joining
techniques; by way of example, the fibers can be
previously woven or then also sintered together.
On account of the high, albeit spatially very
restricted, introduction of heat into the metallic
layer, there is once again a risk of oxide formation on
the fibers, and consequently it is advantageous for the
welding of the fibers to one another to be carried out
- 12 -
under shielding gas. The shielding gas preferably
comprises at least one of the components argon and
helium.
The layer can be compacted immediately before, during
and/or after welding. The compacting of the layer can,
for example, take place in such a manner that the layer
is passed through two rollers, between which there is a
gap, the gap being smaller than the layer thickness.
During the compacting of the layer, it is preferable
for the cavities or pores formed therein to be reduced
in size, with the fibers also being plastically
deformed. It is in this way also possible to achieve a
stronger bond between the fibers. If compacting is to
take place during the welding process, the welding
process is preferably configured as a pressure welding
process. Under certain circumstances, the layer can
also be compacted again, for example, when it is
directly subjected to a second welding process.
After the welding operation, it is also possible to
inspect the welded connections. In this context, an
optical analysis of the moving fiber layer, a targeted
deformation of the fiber layer or also a flow
resistance of the fiber layer can be recorded. During
bending, for example by deformation about a shaft, the
bending forces can be used as a measure of the quality
of the welded connection. It is also possible for the
welded layer to be exposed to an air stream flowing
through it, in which case conclusions as to the welded
connections can be drawn from the deformation of the
layer, the number of fibers which become detached, etc.
In this case, a controlled welding process is
preferred, which therefore opens up the possibility of
adapting the welding process if inadequate welded
connections are established.
According to a further configuration of the process
according to the invention, step d) comprises at least
- 13 -
one of the following operations:
d.1) compacting the layer;
d.2) separating a plurality of fleeces from the
layer;
d.3) classifying the fleeces;
d.4) winding, twisting or folding a fleece;
d.5) structuring a fleece;
d.6) stamping out regions of a fleece;
d.7) combining a fleece with closure elements;
d.8) seaming the layer.
The "compacting" of the layer can be used to set the
desired fleece properties (e.g. density, porosity,
strength, thickness, etc.). A "fleece" is to be
understood in particular as meaning a sheet-like
structure which is formed with predetermined "final"
dimensions and in which the fibers are arranged
randomly or in ordered fashion with respect to one
another. Examples of fleeces include woven fabrics,
mesh structures, knitted fabrics, random layers, etc.
The fleece is in this case preferably formed with
fibers which are made from a corrosion-resistant
material which is able to withstand high temperatures;
this is also intended to apply to all the other
additives of the fleece. The porosity of the fleece
produced is preferably in a range from 30% to 80%, in
particular in a range from 45% to 60%. The fleece has a
preferred weight per unit area in the range from 250 to
1500 g/m2 [grams per square meter].
The separation of a plurality of fleeces (d.2)) from
the layer substantially takes place in a direction
which is transverse to the conveying direction of the
layer; in this context, it is possible to use stamping
tools, blades which move with the layer, i.e. what are
known as flying blades, or similar appliances.
In particular in the case of production with different
fleece properties, i.e. a process variant in which only
- 14 -
a certain number of fleeces are produced with one fiber
fleece property, and then at least one further number
is produced with different fiber fleece properties, it
is advantageous for the fleeces to be classified
accordingly (d.3)). Then, the different fleeces can
also be fed separately to further processing stations.
It is also possible to identify scrap parts during the
classification and to return these scrap parts for
reuse if appropriate.
Whereas hitherto the fleeces were configured as
substantially sheet-like structures located
substantially in one plane, it is now also possible for
the fleeces to be wound and/or twisted and/or stacked
and/or folded after operation d.4) . This is to be
understood as meaning in particular that the fleece
acquires a curvature through plastic deformation.
Following this plastic deformation, the fleece can, for
example, be bent in an S shape, wound up helically,
folded in a star shape, folded in bellows-like fashion,
etc. The deformation of the fleece may also take place
together with further elements of the honeycomb body
(sheet-metal foils, supporting structures, etc.).
In addition to the large-area deformation of the
fleece, there is also the possibility of structuring
the fleece (d.5)). During the structuring, a structure
no larger than the fleece thickness is introduced into
the fleece. Suitable structures are in particular
corrugated structures, zigzag structures and/or
rectangular structures. These structures subsequently
at least partially delimit flow passages of a honeycomb
body. To produce a structure of this type, it is
possible, for example, to use intermeshing corrugated
rollers through which the fleece is guided.
According to step d.6) , it is also possible to stamp
out regions of a fleece. It is in this case possible,
for example, to generate openings which, although
- 15 -
significantly larger than the pores or cavities in the
interior of the fleece, if appropriate also do not
exceed a maximum extent of 20 mm. Openings of this type
can be used, for example, to set defined part-flows in
the interior of the honeycomb body, to form a bypass or
to produce swirling locations in the honeycomb
structure. Furthermore, however, it is also possible
for a very large region of the fleece to be stamped
out, in which case these, for example, disk-shaped
fleeces (if appropriate with a diameter of greater than
70 mm, in particular at least 90 mm) can then
themselves in turn be used as filter medium, for
example in a radial-flow honeycomb body. Of course, a
plurality of stamping operations or types of stamping
can be carried out simultaneously.
Finally, the fleece can also be combined with closure
elements (d.7)). These are preferably arranged close to
an edge of the fleece and for example have a sealing
function with respect to the honeycomb body and/or
serve for attaching further fleeces and/or housing
parts. The closure element used may, for example, be a
cord, a sheet-metal strip, an element comprising sinter
material, a perforated mask, etc.
According to d.8), seaming of the layer is also
proposed. This is to be understood in particular as
meaning that the edges of the layer which run in the
direction of extent of the layer run substantially
parallel, and/or a desired width of the layer is
maintained. This can be realized, for example, by
removing fibers, with the layer preferably being cut to
size.
According to a further configuration of the process,
step e) comprises at least one of the following
operations:
e.1) combining at least one fleece with at least one
element selected from the group consisting of:
- 16 -
at least one metal foil, at least one housing,
at least one electrode, at least one honeycomb
structure, at least one perforated tube;
e.2) applying glue to at least one fleece or an
element connected to it;
e.3) applying solder to at least one fleece or an
element connected to it.
The metal foil is preferably a foil with a thickness of
less than 0.15 mm, in particular in the range from
0.03 mm to 0.12 mm. The metal foil comprises chromium
and aluminum and is based on a steel material which is
thermally stable and corrosion-resistant. The metal
foil preferably has a corrugated structure. The housing
is preferably likewise metallic and in addition to
round, oval or polygonal cross sections, may also have
any other desired cross section. The housing at least
partially accommodates the fleece and/or the metal foil
in its interior. The provision of an electrode is
recommended in particular if the honeycomb body is to
be designed to be electrically heatable. For this
purpose, the honeycomb body may also be assigned
insulation layers which partially form a defined flow
path through the honeycomb body. When a voltage is
applied, the fleece and/or metal foil is heated up in a
controllable way on account of Joule resistance
heating. The heating of the honeycomb body may be
advantageous, for example, during the cold-start phase
of the exhaust system and/or for the thermal
regeneration of a honeycomb body used as a particulate
trap. Furthermore, by way of example it is also
possible for the honeycomb body together with a further
honeycomb structure to be positioned in a single
housing. The honeycomb structure can fundamentally be
formed using metal foils or (extruded) ceramic
material. If a radial-flow honeycomb body is to be
produced, by way of example it is possible for fleeces
which have been stamped out in disk shapes to be
arranged at defined intervals around at least one
- 17 -
perforated tube or within a perforated tube, allowing
the gas stream to flow through from regions located on
the inner side to regions located on the radially outer
side.
At the same time as or at a different time than the
combining of the at least one fleece with at least one
element selected from the group, it is also possible
for the fleece and/or an element which is to be
connected to it to be at least partially covered with
glue. The application of glue (bonding agent, adhesive,
etc.) can be carried out by means of strip material,
self-adhesive stickers, a printing process, etc.
Likewise at the same time as and/or after the combining
operation in accordance with step e.1), it is possible
for solder to be applied to at least part of at least
one fleece and/or an element connected to it. The
solder material can likewise be applied in the form of
strip material, stickers and/or by a printing process.
However, it is also possible for a solder in powder
form, which sticks to the subregions which have
previously been provided with glue, to be fed to the
honeycomb body. With regard to the techniques used to
apply glue and solder to a honeycomb structure,
reference is made in particular to the methods which
are already known, in particular in the name of the
Applicant, which can be used in full for further
details.
Finally, the invention also proposes a honeycomb body
having at least one fleece produced by a process of the
type described above in accordance with the invention,
the honeycomb body being designed with passages which
are closed on alternate sides, and the at least one
fleece having at least one fleece property which is
designed to be different over the thickness of the
fleece. In principle, the honeycomb bodies can be
produced with a large number of configurations in
- 18 -
accordance with the above-described process, for
example in the manner of a radial-flow honeycomb body,
with passages arranged in a star shape, with passages
in the form of a ring or a bellows or as an open
particulate trap in which none of the filter passages
is completely closed. However, in particular with a
view to a honeycomb body being used in the exhaust
system of mobile internal combustion engines (spark-
ignition and diesel engines) with a very high purifying
action with regard to the particulates contained in the
exhaust gas, the invention here proposes a honeycomb
body which has passages that are closed on alternate
sides. For this purpose, the honeycomb body is designed
with at least one closure element at the end sides, so
that (preferably) all the passages are closed either at
one end side or the other. This has the effect, for
example, of ensuring that the entire exhaust-gas stream
has to flow through a metallic fleece at least once.
In this context, it is proposed here that a fleece
property be designed to be different over the thickness
of the fleece, for example the porosity, the type of
fibers, the provision of additives, etc. Under certain
circumstances, it may also be advantageous for this
and/or another fleece property to vary perpendicular to
the fleece thickness, i.e. for example in the axial
direction of the honeycomb body. The combination of a
passage system which is closed on alternate sides and
the differently configured fleece property has the
advantage that the flow through the closure elements is
diverted in defined directions through the fleece in a
manner which can be accurately predicted. The fleece
can now be adapted to these flow properties of the
exhaust gas, so that, for example, particulates of
different sizes are absorbed or accumulated in
different regions of the fleece. This targeted
absorption or accumulation of particulates can promote
efficient conversion of these pollutants, for example
by the provision of a catalyst in the vicinity. It is
- 19 -
preferable for a honeycomb body of this type to be
formed with a combination of at least one fleece and at
least one corrugated metal foil.
It is preferable for the honeycomb body described above
to be used for filtering an exhaust-gas stream. A
particular application area which should be mentioned
is the automobile industry, in which case this
honeycomb body may form part of a more complex exhaust
system, in which the honeycomb body is combined with at
least one catalytic converter, an adsorber, an SCR
catalyst, a particulate trap, etc.
The invention and the technical background are
described in more detail below with reference to the
figures. The figures also show particularly preferred
configurations of the invention, although without the
invention being restricted to these configurations. It
should be noted that the illustrations in the figures
are purely schematic in nature and are not generally
suitable for illustrating size ratios. In the drawings:
Fig. 1 diagrammatically depicts a variant embodiment
of a process for producing a honeycomb body
with at least one fleece having metallic
fibers;
Fig. 2 shows a honeycomb body which is closed on
alternate sides;
Fig. 3 shows a radial-flow honeycomb body;
Fig. 4 shows an electrically heatable exhaust-gas
treatment unit with a honeycomb body;
Fig. 5 shows a fleece having metallic fibers, and
Fig. 6 diagrammatically depicts a further variant
embodiment of a process for producing a
- 20 -
honeycomb body.
Fig. 1 illustrates a variant embodiment of the process
for producing a honeycomb body, the figure
schematically indicating, on the left-hand side, the
process steps referred to by their short designations
here, while the right-hand side of the figure
illustrates an example of a configuration of this
process step.
Accordingly, first of all, according to step a. 3),
discontinuous removal from a metal melt 15 is carried
out to produce metallic fibers 3. In this case, a rotor
16 which rotates within the metal melt 15 generates
fibers 3 which to set are fed to a tray 33.
The fibers 3 produced in this way are then classified
in accordance with step ab.l). For this purpose the
fibers 3 are fed to a sorter 17 which simultaneously
also effects selection or separation of the different
fibers 3, for example as a function of the shape and/or
size of the fibers 3.
These fibers are then fed to a distributor 18 which
layers the fibers uniformly on a base 5 to form a layer
4 (cf. step b.1)). The base 5 is in this case designed
as a conveyor belt, so that the layer 4 which is
generated can then be fed to a welding process.
After step c.2), the layer 4 is passed through a
welding installation 19, which is suitable for carrying
out a roller seam welding operation at least once.
After this, in accordance with step d.2), the layer 4
is converted into separate fleeces 2 of a predetermined
fleece thickness 14 and fleece length 22, which is done
by separating the fleeces 2 by means of a separation
apparatus 20.
- 21 -
The fleeces 2 produced in this way are then combined
with a plurality of corrugated metal foils 8 so as to
form a honeycomb body 1 having a multiplicity of
passages 13 (step e.1)).
To form connections between the individual elements of
the honeycomb body by a joining technique and/or to
further develop the connections between the fibers made
by a joining technique, the honeycomb body 1 is then
also subjected to a brazing process (step f)) , the
honeycomb body 1 being fed at least from time to time
and preferably continuously to a furnace 21, in which a
vacuum and temperatures above 1000°C preferably
prevail. The honeycomb body 1 produced in this way is
particularly suitable for use in the exhaust system of
automobiles.
Fig. 2 shows a possible variant embodiment of a
honeycomb body 1 produced by the process according to
the invention. The honeycomb body 1 once again has a
multiplicity of passages 13, which in this case are
closed off on alternate sides by means of closure
elements 7 which are each secured to one end side 23.
In this way, the exhaust gas is forced first of all to
enter an open passage 13 in the direction of flow 24,
but then, on account of the closure element 7, to flow
through the fleece 2 and pass into another, adjacent
passage 13. During passage through the fleece 2, in
particular particulates (such as soot and ash) are
retained. To prevent passages 13 becoming unusable on
account of soot accumulating over an excessive area,
regions 6 are stamped out of the fleece 2, so as to
form a type of "bypass". The honeycomb body 1 is
surrounded by a metallic housing 9.
Fig. 3 illustrates a further configuration of a
honeycomb body 1 as can be produced by the process.
This honeycomb body 1 has a star-shaped structure and
medium flows radially through it from the inside
- 22 -
outward. For this purpose, the exhaust gas passes
through a tube 12, which is provided with a perforation
in the region of the honeycomb body 1. As a result, the
exhaust gas passes into the pockets 25 which are formed
by the fleece 2 and form the passages 13. The exhaust
gas emerges through these pockets 25 substantially
radially with respect to the axis 26 and on the outer
side is discharged again in a substantially axial
direction.
Fig. 4 illustrates an exhaust-gas treatment unit 34
which is designed as an electrically heatable honeycomb
body 1. The honeycomb body 1 itself is once again
formed with a combination of metallic fleece 2 and
metal foils 8, in such a way as to form (open) passages
13 which run substantially parallel to one another.
Even if the passages 13 are mostly not completely
closed, the metal foils 8 do have flow-influencing
means 29 which at least partially project into the
passages 13 and are responsible for diverting parts of
the exhaust-gas streams through the fleece 2. This
honeycomb body 1 is arranged in a housing 9.
A further honeycomb structure 11, which may be
configured for example as an oxidation catalyst, is
provided at the end side of the honeycomb body 1. The
honeycomb structure 11 is connected to the honeycomb
body 1 by means of (at least partially electrically
insulated) pins 27. The contact-connection of the
honeycomb structure 11 for a flow of electric current
is effected by means of the electrodes 10 which are
diagrammatically depicted. It is therefore possible for
the exhaust gas which comes into contact with the
honeycomb structure 11 first of all as seen in the
direction of flow 24 to be heated up and in the
process, for example, also allowing thermal
regeneration of the downstream particulate trap
comprising the honeycomb body 1. The entire arrangement
of the honeycomb body 1 with the combination of the
- 23 -
honeycomb structure 11 is integrated in the exhaust
pipe 28, for example of a motor vehicle.
Fig. 5 now illustrates in detail one configuration of
the fleece 2, which comprises a multiplicity of
metallic fibers 3. The fibers 3 are arranged as a
random layer and are connected to one another in
separate connection zones 30. The connection zones 30
are designed at a spacing 31 and with a width 32 which
are substantially characterized by the execution of,
for example, the roller seam welding. It should be
noted here that under certain circumstances the width
32 may also be designed to be greater than the spacing
31. It can be seen from Fig. 5 that the fleece 2 is a
substantially sheet-like structure, the smallest
dimension generally being the fleece thickness 14. The
formation of the connection zones 30 can also serve to
realize an anisotropic formation of at least one fiber
fleece property. In addition to the connection zones 3 0
illustrated here, it is possible to generate further
connections by a joining technique between the fibers
3, for example sintered connections which are produced
during process step f) .
Fig. 6 diagrammatically depicts a further variant
embodiment of the process for producing a honeycomb
body 1 through to production of the fleeces 2. To
complete the honeycomb body 1, reference may be made to
joining methods described above. The fiber production
in this case uses a cutting installation 35 which is
supplied with a plurality of metallic wires 36. The
cutting installation 35 has a cutting mechanism which
cuts the long wires 36 into short fibers 3 in a
controlled way. The fibers 2 produced in this way are
classified and selected in a sorter 17 before then
being fed to different distributors 18. A layer 4 is
produced in two stations, four distributors 18 being
arranged above a base 5 configured as a conveyor belt
within a first station, illustrated on the left, and
- 24 -
this conveyor belt then checks the layer 4 produced for
its fleece property by means of a balance 37, and the
fleece is then filled in a targeted way with the
established quantity of fibers 3 that is still required
if appropriate in a second station comprising a further
distributor 18.
Once the desired weight per unit area of the layer 4 is
present, the latter is fed to a first deformation
installation 38 in the conveying direction 40. There,
the layer 4 is compacted and the edges of the layer 4
are precut. The fiber material which is separated off
during the precutting, preferably amounting to less
than 10% of the fiber material used, is returned to the
first station or at least one of the distributors 18 or
the sorter 17. The pretreated layer 4 then passes
through a welding installation 19 which is suitable for
carrying out roller seam welding at a welding rate of
at least 4 m/min for a layer width in the range of over
100 mm. After the fibers 3 have been captively joined
to one another, the layer finally passes through a
further deformation installation 38, in which further
compacting is carried out and separate fleeces 2 with
predetermined dimensions are separated. These fleeces 2
can then be fed to further processing stations to form
a honeycomb body 1. The method illustrated here for
producing the fleeces 2 is suitable in particular for
series production, since high conveying and welding
rates can be realized and at the same time a controlled
addition of fibers to produce desired fleece properties
is possible.
The proposed processes are suitable in particular for
the series production of particulate traps for exhaust
systems of automobiles.
- 25 -
List of designations
1 Honeycomb body
2 Fleece
3 Fiber
4 Layer
5 Base
6 Region
7 Closure element
8 Metal foil
9 Housing
10 Electrode
11 Honeycomb structure
12 Tube
13 Passage
14 Fleece thickness
15 Metal melt
16 Rotor
17 Sorter
18 Distributor
19 Welding installation
20 Separation apparatus
21 Furnace
22 Fleece length
23 End side
24 Direction of flow
25 Pocket
26 Axis
27 Pin
28 Exhaust pipe
29 Flow-influencing means
30 Connection zone
31 Spacing
32 Width
33 Tray
34 Exhaust-gas treatment unit
35 Cutting installation
36 Wire
3 7 Balance
- 26 -
38 Deformation installation
39 Fiber return
40 Conveying direction
- 27 -
Patent Claims
1. A process for producing a honeycomb body (1) with
at least one fleece (2) having metallic fibers (3) ,
which comprises at least the following steps:
a) producing metallic fibers (3) ;
b) forming a layer (4) comprising metallic fibers
(3);
c) welding the metallic fibers (3) to one another;
d) deforming the layer (4) to form a fleece (2)
having defined fleece properties;
e) producing a honeycomb body (1);
f) brazing the honeycomb body (1).
2. The process as claimed in claim 1, in which step
a) comprises at least one of the following production
methods:
a.1) separating from a metal block;
a.2) continuous fiber production from a metal melt
(15) ;
a.3) discontinuous removal from a metal melt (15) .
3. The process as claimed in claim 1 or 2, in which
during step a) at least from time to time measures are
taken to avoid an oxide layer on the fibers (3) .
4. The process as claimed in one of the preceding
claims, in which between step a) and step b) at least
the step ab) of fiber preparation is also carried out,
comprising at least one of the following operations:
ab.1) classifying the fibers (3);
ab.2) selecting the fibers (3);
ab.3) returning the fibers (3) for reuse;
ab.4) cutting the fibers (3) ;
ab.5) mixing the fibers (3);
ab.6) cleaning the fibers (3) .
5. The process as claimed in one of the preceding
claims, in which step b) comprises at least one of the
- 28 -
following operations:
b.1) distributing fibers (3) on a base (5);
b.2) adding at least one additive;
b.3) determining at least one layer parameter;
b.4) altering the at least one layer parameter;
b.5) continuously moving the layer (4).
6. The process as claimed in one of the preceding
claims, in which step c) comprises at least one of the
following operations:
c.1) carrying out resistance welding at least once;
c.2) carrying out roller seam welding at least once;
c.3) welding under shielding gas;
c.4) compacting the layer (4);
c.5) inspecting the welded joins.
7. The process as claimed in one of the preceding
claims, in which step d) comprises at least one of the
following operations:
d.1) compacting the layer (4);
d.2) separating a plurality of fleeces (2) from the
layer (4) ;
d.3) classifying the fleeces (2);
d.4) winding, twisting or folding a fleece (1);
d.5) structuring a fleece (2);
d.6) stamping out regions (6) of a fleece (2) ;
d.7) combining a fleece (2) with at least one closure
element (7);
d.8) seaming the layer (4) .
8. The process as claimed in one of the preceding
claims, in which step e) comprises at least one of the
following operations:
e.1) combining at least one fleece (2) with at least
one element selected from the group consisting
of: at least one metal foil (8) , at least one
housing (9) , at least one electrode (10), at
least one honeycomb structure (11) , at least one
- 29 -
perforated tube (12);
e.2) applying glue to at least one fleece (2) or an
element connected to it;
e.3) applying solder to at least one fleece (2) or an
element connected to it.
9. A honeycomb body (1) having at least one fleece
(2) produced by the process as claimed in one of the
preceding claims, the honeycomb body (1) being designed
with passages (13) which are closed on alternate sides,
and the at least one fleece (2) having at least one
fleece property which is designed to be different over
the thickness (14) of the fleece.
10. The use of the honeycomb body (1) as claimed in
claim 9 for filtering an exhaust-gas stream.

A process for producing a honeycomb body (1) with at least one fleece (2) having metallic fibers (3), which comprises at least the following steps:
a) producing metallic fibers (3);
b) forming a layer (4) comprising metallic fibers
(3);
c) welding the metallic fibers (3) to one another;
d) deforming the layer (4) to form a fleece (2)
having defined fleece properties;
e) producing a honeycomb body (1);
f) brazing the honeycomb body (1).
A honeycomb body produced in this way is suitable in particular for filtering exhaust gases from a motor vehicle.

Documents:

00201-kolnp-2008-abstract.pdf

00201-kolnp-2008-claims.pdf

00201-kolnp-2008-correspondence others.pdf

00201-kolnp-2008-description complete.pdf

00201-kolnp-2008-drawings.pdf

00201-kolnp-2008-form 1.pdf

00201-kolnp-2008-form 2.pdf

00201-kolnp-2008-form 3.pdf

00201-kolnp-2008-form 5.pdf

00201-kolnp-2008-gpa.pdf

00201-kolnp-2008-international publication.pdf

00201-kolnp-2008-international search report.pdf

00201-kolnp-2008-translated copy of priority document.pdf

201-KOLNP-2008-(12-06-2013)-ABSTRACT.pdf

201-KOLNP-2008-(12-06-2013)-AMANDED CLAIMS.pdf

201-KOLNP-2008-(12-06-2013)-ANNEXURE TO FORM 3.pdf

201-KOLNP-2008-(12-06-2013)-CLAIMS.pdf

201-KOLNP-2008-(12-06-2013)-CORRESPONDENCE.pdf

201-KOLNP-2008-(12-06-2013)-DESCRIPTION (COMPLETE).pdf

201-KOLNP-2008-(12-06-2013)-FORM-2.pdf

201-KOLNP-2008-(12-06-2013)-OTHERS.pdf

201-KOLNP-2008-(28-02-2013)-ABSTRACT.pdf

201-KOLNP-2008-(28-02-2013)-ANNEXURE TO FORM-3.pdf

201-KOLNP-2008-(28-02-2013)-CLAIMS.pdf

201-KOLNP-2008-(28-02-2013)-DESCRIPTION (COMPLETE).pdf

201-KOLNP-2008-(28-02-2013)-DRAWINGS.pdf

201-KOLNP-2008-(28-02-2013)-EXAMINATION REPORT REPLY RECEIVED.pdf

201-KOLNP-2008-(28-02-2013)-FORM-1.pdf

201-KOLNP-2008-(28-02-2013)-FORM-2.pdf

201-KOLNP-2008-(28-02-2013)-OTHERS.pdf

201-KOLNP-2008-(28-02-2013)-PETITION UNDER RULE 137.pdf

201-KOLNP-2008-CORRESPONDENCE OTHERS-1.1.pdf

201-KOLNP-2008-CORRESPONDENCE.pdf

201-kolnp-2008-form 18.pdf

201-KOLNP-2008-PCT REQUEST FORM.pdf

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Patent Number

258109

Indian Patent Application Number

201/KOLNP/2008

PG Journal Number

49/2013

Publication Date

06-Dec-2013

Grant Date

04-Dec-2013

Date of Filing

15-Jan-2008

Name of Patentee

EMITEC GESELLSCHAFT FUR EMISSIONSTECHNOLOGIE MBH

Applicant Address

HAUPTSTRASSE 128, 53797 LOHMAR

Inventors:

#	Inventor's Name	Inventor's Address
1	BRUCK, ROLF	FROBELSTRASSE 12, 51429 BERGISCH GLADBACH

PCT International Classification Number

B23P 15/00

PCT International Application Number

PCT/EP2006/005534

PCT International Filing date

2006-06-09

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2005 028 031.5	2005-06-17	Germany