Title of Invention	A PROCESS FOR PRODUCING STRUCTURES SUPERIMPOSED ON ONE ANOTHER IN A METAL FOIL SECTION AND AN APPARATUS FOR PRODUCING THE SAME
Abstract	A process for producing structures which are superimposed on one another in a metal foil section (1), comprising at least the following steps: a) producing a primary structure (2) using a first tool (3); b) transferring the metal foil section (1) to a second tool (4), the second tool (4) having at least one shaping profiled roller (5) which is responsible for transferring the metal foil section (1); c) producing a secondary structure (6) using the second tool (4); d) determining a spatial position of primary structure (2) and secondary structure (6) in at least one subreglon (7) of the metal foil section (1); e) detecting an incorrect position and adapting an operating parameter of the at least one profiled roller (5). The invention also proposes an apparatus suitable for this process and metal foils producible thereby, which are suitable for the production of catalyst support bodies that can be used in exhaust systems of internal combustion engines.

Title of Invention

A PROCESS FOR PRODUCING STRUCTURES SUPERIMPOSED ON ONE ANOTHER IN A METAL FOIL SECTION AND AN APPARATUS FOR PRODUCING THE SAME

Abstract

A process for producing structures which are superimposed on one another in a metal foil section (1), comprising at least the following steps: a) producing a primary structure (2) using a first tool (3); b) transferring the metal foil section (1) to a second tool (4), the second tool (4) having at least one shaping profiled roller (5) which is responsible for transferring the metal foil section (1); c) producing a secondary structure (6) using the second tool (4); d) determining a spatial position of primary structure (2) and secondary structure (6) in at least one subreglon (7) of the metal foil section (1); e) detecting an incorrect position and adapting an operating parameter of the at least one profiled roller (5). The invention also proposes an apparatus suitable for this process and metal foils producible thereby, which are suitable for the production of catalyst support bodies that can be used in exhaust systems of internal combustion engines.

Full Text	The invention relates to a process for producing structures superimposed on one another in a metal foil section and an apparatus for producing the same. Metal foil sections of this type are preferably used to construct honeycomb bodies that are used, for example, as exhaust-gas treatment components in exhaust systems of internal combustion engines. For the exhaust-gas treatment of mobile internal combustion engines, such as for example spark-ignition and diesel engines, it is known to arrange at least one exhaust- gas treatment component, which provides a relatively large surface area (such as what Is known as a honeycomb body), in the exhaust pipe. These components are if appropriate provided with an application-specific (e.g. adsorbing, catalytlcally active and/or other) coating, intimate contact with the exhaust gas flowing past being realized on account of the large surface area of the component. Examples of these components include filter elements for filtering out particulates contained In the exhaust gas, adsorbers for storing pollutants (e.g. NO*) contained in the exhaust gas for at least a limited time, catalytic converters (e.g. 3-way catalyst, oxidation catalyst, reduction catalyst, etc.), diffusors for influencing the flow of and/or swirling up the exhaust gas flowing through or also heating elements which heat the exhaust gas to a desired temperature in particular after an internal combustion engine cold start. The following support substrates have fundamentally proven suitable for the conditions of use in the exhaust system of an automobile: ceramic honeycomb bodies, extruded honeycomb bodies and honeycomb bodies made from metal foils. In view of the fact that these support substrates always need to be adapted to their corresponding function, high- temperature-resistant and corrosion-resistant metal foils represent especially suitable starting materials for their production. It ia known to produce honeycomb bodies using a plurality of at least partially structured metal sheets, which are then introduced into a housing and thereby form a support body which can be provided with one or more of the abovementloned coatings. The at least partially structured metal sheets are arranged in such a way as to form passages arranged substantially parallel to one another. To ensure this, some of the metal sheets are provided with a structure, for example a type of corrugation structure, sawtooth structure, square-wave structure, delta-wave structure, omega structure or the like. Furthermore, it is known to introduce a second structure into sheet-metal foils of this type, this second structure being intended in particular to prevent a laminar flow, with which gas exchange between regions of the exhaust-gas part-stream located in the center of a passage of this type and the, for example, catalytically active passage wall regions does not take place to a sufficient extent, from forming immediately after the exhaust gas has entered the honeycomb body. This second structure or microstructure provides flow- facing surfaces which are responsible for swirling up the exhaust-gas part-streams in the interior of a passage of this type. This leads to intensive mixing of the exhaust gas part-streams themselves, thereby ensuring intimate contact between the pollutants contained in the exhaust gas and the passage wall. Furthermore, it is possible to use second structures of this type to form flow ducts running transversely to the passage, allowing gas exchange between exhaust-gas part-streams in adjacent passages. For this reason, it is known to use microstmctures which comprise, for example, guide surfaces, studs, projections, vanes, tabs, holes or the like. In this respect, there is a very considerable range of variation when producing metallic honeycomb bodies of this type compared to honeycomb bodies made from ceramic material, since such complex passage walls cannot be realized, or can only be realized with a particularly high level of technical outlay, using ceramic material. These metal sheets provided with structures are then stacked (if appropriate alternately with smooth interlayers between them), intertwined and inserted into a housing, leading to the formation of a honeycomb body which has passages that are substantially parallel to one another. Furthermore, in the context of exhaust-gas treatment it is of particular interest for pollutants contained in the exhaust gas to be converted virtually immediately after the internal combustion engine has started up. This should take place with a particularly high efficiency in accordance with statutory stipulations and guidelines. For this reason, ever thinner metal sheets have been used in the past. These thinner sheets provide a very low area-specific heat capacity, i.e. relatively little heat is withdrawn from the exhaust gas flowing past, or the temperature of the metal sheets themselves rises relatively quickly. This is important because the catalytically active coatings which are currently used in the exhaust system only start to convert the pollutants above a certain light- off temperature, which is approximately 230°C to 270°C. With a view to converting these pollutants with at least a 98% efficiency after just a few seconds, metal sheets with a thickness of, for example, less than 0.1 mm, in particular even less than 0.05 mm, are used. However, the abovementioned objectives give rise to a number of manufacturing technology and application- related problems. For example, it should be noted that under certain circumstances the targeted setting of an exhaust gas flow profile in the honeycomb body requires precise alignment of the microstructures in the passages. Furthermore, it should be borne in mind that metal foils of this type are connected to one another by joining techniques, in particular are soldered together (by brazing, if appropriate under a vacuum) and/or are welded to one another. However, this presupposes the presence of defined contact regions between the metal foils. This in turn means that it is necessary to ensure that the structures which are superimposed on one another are aligned as accurately as possible. Hitherto, it has not been possible to ensure this with a sufficient level of accuracy. On account of external influences involved in the production of the structures, such as for example vibrations excited in the metal foils, deviations occur in the drawing and/or forming properties of the metal foil. Manufacturing inaccuracies or tolerances within the tools (such as for example true-running errors, positioning errors, contour errors in rolling teeth, etc.) lead to undesirable deviations in the positions of the structures with respect to one another which periodically fluctuate. Moreover, inliomogeneities in the material used for the metal foils can lead to further deviations in the structures with respect to one another. It is an object of the present invention to at least partially alleviate the technical problems which have been outlined in connection with the prior art. In particular, it is intended to provide a process for producing multiply structured metal foils of this type which ensures that the structures which are superimposed on one another are aligned as accurately as possible with respect to one another. The process is also to satisfy the demands of series production for metal foils of this type and to represent a time-saving and cost-saving route. Furthermore, it is intended to provide an apparatus for producing metal foils of this type, The metal foils produced by the process and/or the apparatus are to have a particularly accurate alignment of the structures which are superimposed on one another and are to be used In particular to produce durable honeycomb bodies which can be used in the exhaust system of internal combustion engines. These objects are achieved by the process of producing superimposed primary and secondary structures and by the apparatus for producing the same. Further advantageous configurations of the process and apparatus are given in the dependent patent claims. The invention also proposes a metal foil section produced by the process and/or the apparatus and a honeycomb body produced therefrom. The features listed individually In the patent claims can be combined with one another in any technically appropriate way and can be supplemented by explanatory statements from the description, thereby demonstrating further variant embodiments of the invention. The process according to the invention for producing structures which are superimposed on one another in a metal foil section includes at least the following steps: a) producing a primary structure using a first tool; b) transferring the metal foil section to a second tool, the second tool having at least one shaping profiled roller which is responsible for transferring the metal foil section; c) producing a secondary structure using the second tool; d) determining a spatial position of primary structure and secondary structure in at least one subreglon of the metal foil section; e) detecting an incorrect position and adapting an operating parameter of the at least one profiled roller. It is customary for structures of this type to be produced in a continuous process (or with a frequency of greater than 1 advancing step per second), with the metal foil being unrolled from a coil and fed to the tools. Therefore, the process outlined here considers a metal foil section which is deformed. Accordingly, the metal foil section is initially smooth and is fed to the first tool to produce a primary structure. The primary structure is in this case preferably a microstructure, i.e. for example an embossed or stamped formation, which extends only over a small region of the metal foil section and is intended in particular to influence the subsequent flow of the exhaust gas in the passage. In addition, a primary structure of this type may also represent a preparatory measure for the subsequent formation of (other or further) microstructures, for example slots, at which subregions of the metal foil are subsequently deformed so as to produce guide surfaces or the like. As explained in step b), the metal foil section is transferred by a profiled roller of the second tool. In other words, the second tool pulls the metal foil section through the first tool. Although it is also possible for apparatuses for clamping and/or guiding the metal foil section to be provided upstream of the first tool and/or between the first tool and the second tool, the advance of the metal foil section at the desired velocity or cycle rate is determined by the profiled roller. In addition to the shaping, i.e. the production of a secondary structure (step c)), the profiled roller also has a transporting function for the metal foil section. Engagement of the profiled roller in the secondary structure of the metal foil section allows a force to be introduced parallel to the direction of advance of the metal foil section, with the rotational speed of the profiled roller determining the speed of advance of the metal foil section. After the primary structure and the secondary structure (as well as any further structures) have been formed, in accordance with step d) the spatial position of these structures which are superimposed on one another is then recorded. In this step, it is preferable to in each case record reference points of the primary structure and the secondary structure and to evaluate the position of these reference points with respect to one another. It is possible for their position with respect to one another to be recorded in one or more planes (parallel, perpendicular and/or oblique with respect to the surface of the smooth metal foil section). In particular center points and/or center lines of the primary structure are recommended as reference points for the primary structure. By way of example, the extremities of the secondary structure, such as for example the . corrugation peaks or corrugation valleys in the case of a corrugated structure, are recommended as reference points for the secondary structure. After the spatial position of primary structure and secondary structure has been determined, their spatial position is evaluated. In this context, it is possible to predetermine different tolerance ranges or limit values, which differentiate an acceptable position (correct position) and an incorrect position from one another. If the result of step d) is that an incorrect position is present, at least one operating parameter of the at least one profiled roller is then altered in accordance with step e). A suitable operating parameter is in particular the rotational speed of the profiled roller, although under certain circumstances it is also possible to carry out adaptations by varying the position of the profiled roller with respect to other components of the second tool, in particular a further profiled roller. Adaptation of this nature leads to the shaping profile of the profiled roller being realigned with respect to the distance to the first tool, thereby altering the position of the secondary structure in the metal foil section relative to the primary structure. This brings about accurate alignment of primary structure and secondary structure. The process proposed here allows highly dynamic control of the process for producing metal foils of this type with structures which are superimposed on one another, in which it is possible to automatically react quickly to material inhomogeneities, external disruptions or the like. Furthermore, it is proposed that the at least one profiled roller is operated at an angular velocity which is altered in step e). The profiled rollers used to produce the secondary structure have hitherto been operated at a constant angular velocity, with one revolution of the profiled roller if appropriate being divided into a multiplicity of rotation angle sections or increments and rotation continuing by a constant number of increments at predetermined time intervals. The present invention now departs from this procedure. If an incorrect position is detected, a correction is achieved by virtue of either continuing to rotate for a selected, constant number of increments but in an altered time interval and/or by the number of increments being varied while maintaining a constant time interval. In view of the fact that control of this nature is only launched when an incorrect position is detected, phases during which a constant angular velocity is present may also occur during the process, so that under certain circumstances a relatively long period of time (for example 5 minutes) needs to be considered with regard to a varying angular velocity. However, it is particularly advantageous if step d) is carried out at least once per revolution of the at least one profiled roller. This means that a check of the spatial position of primary structure and secondary structure is carried out at the latest after every revolution of the profiled roller. This has the advantage that this control system is highly dynamic and can also react quickly to faults, such as for example the occurrence of vibrations. It is also preferable if step e) is carried out at least once per revolution of the profiled roller. It is in this case possible for the adapting of the at least one operating parameter of the at least one profiled roller to be controlled in such a way that the incorrect position is corrected at the latest after one revolution, in particular if step d) is carried out only after each revolution. However, for an even more dynamic control system, it is advantageous for steps d) and e) to be carried out a number of times per revolution of the profiled roller in order for a correction to take place in less than one revolution of the profiled roller. In the latter case, steps d) and e) are preferably carried out at least twice and in particular at least four times per revolution of the profiled roller. If the position of the profiled roller with respect to other components can be altered as operating parameter, the configuration of the secondary structure is altered. This means, for example, that the shaping sections of the profiled rollers engage in one another to a greater extent and the secondary structure is thereby produced with a greater height. This leads to a higher demand for material per segment of secondary structure, so that in this way it is likewise possible to shift the position of the primary structure and secondary structure relative to one another. With a view to the production of a honeycomb body, this leads to the formation of passages with different passage cross sections, which may be advantageous in certain applications. However, to accurately influence the flow properties of the exhaust gas in the honeycomb body in this way, very accurate control of the position of the profiled rollers is required. According to a preferred configuration of the process, step a) comprises the stamping of openings and step c) comprises the shaping of corrugations into the metal foil section. The openings may be designed as slots, holes or the like. The corrugations are substantially characterized by corrugation peaks and corrugation valleys, with the openings being aligned with respect to these corrugation peaks and corrugation valleys. In this case, it is preferable for the spatial position of the openings and corrugations in the direction of advance and in a plane of the metal foil section to be determined and adapted. Although this is a preferred variant, it is in particular also possible for openings to be introduced into the metal foil section by means of a rotary stamping tool and/or a laser. In principle, it is also possible for a plurality of primary structures or openings to be introduced simultaneously, so that after step a) the metal foil section has a plurality of rows of primary structures or openings. Furthermore, it is proposed that an incorrect position involves a position shift from primary structure to secondary structure of greater than 0.3 mm. This produces a limit value used to distinguish a correct position from an incorrect position. The position shift is preferably considered in the direction of advance of the metal foil section. The reference points used for the primary structure and the secondary structure may be their center points or center lines. If the primary structure is formed by openings designed as slots, their center line should be parallel to the profile of the corrugation peaks or corrugation valleys. The maximum position shift which is still permissible from primary structure to secondary structure is preferably below an absolute value of 0.2 nun, in particular below 0.1 mm. According to a further configuration of the process, the detection of an incorrect position ia carried out by means of at least one optical sensor. This optical sensor is arranged downstream of the second tool (or a subsequent tool) and therefore observes the spatial position of the primary structure and secondary structure which have currently been formed. A recommended optical sensor is in particular a camera, the picture resolution (pixels) of which permits the determination of a position shift. These pixels can be used, for example, to determine the position shift and to effect a corresponding adjustment to the angular velocity of the at least one profiled roller. A further aspect of the invention proposes an apparatus for producing structures which are superimposed on one another, comprising at least the following components: a first tool, which is able to produce openings in a metal foil section, a second tool, which has a pair of shaping profiled rollers through which a metal foil section can be passed to produce corrugations, the pair of profiled rollers being able to effect an advance of the metal foil section through the first tool and the second tool, an appliance for driving at least one profiled roller of the second tool, at least one optical sensor which is connected downstream of the second tool as seen in a direction of advance, and at least one control unit, which is connected to the sensor and the appliance. This apparatus is suitable in particular for carrying out a process which has been described in accordance with the invention. In the apparatus described here, the first tool is preferably a stamping machine which removes subregiona of the metal foil section. The second tool is preferably a corrugation rolling machine. Electric motors or servomotors may be advantageous as the appliance for driving at least one profiled roller. It is preferable for the at least one profiled roller to be driven with a frequency of greater than 6 Hz [1/second], in particular greater than 8 Hz or even 12 Hz. The at least one optical sensor preferably comprises a camera. The at least one control unit evaluates the data from the at least one optical sensor and determines a spatial position of primary structure and secondary structure. Moreover, the control unit detects an incorrect position and then adapts an operating parameter of the appliance used to drive the at least one profiled roller. The control unit may comprise image recognition means, data processing programs, memory elements and the like. Preference is given to an apparatus in which the at least one sensor is configured in such a way that it has a variable detection field. This is to be understood in particular as meaning that the detection field can be positioned variably with respect to the metal foil section. This preferably ensures a movement of the detection field in the direction of advance or perpendicular to the direction of advance, it being possible for this movement to be realized by translational movements and/or by pivoting of the sensor. It is in this way also possible to record major position shifts (as may occur for example when starting the production process or during a material change). Moreover, it is possible to use a single sensor to record the reference points for the primary structure and the secondary structure at various regions of the metal foil section. It is in this way possible to keep the technical outlay involved in determining the spatial position of primary structure and secondary structure at a low level. Furthermore, it is proposed that the at least one sensor is assigned a measuring roller which positions a metal foil section with respect to the at least one sensor. The measuring roller, which does not itself effect any permanent deformation of the structures, but rather is merely responsible for accurately guiding the metal foil section, produces, for example, an accurate alignment of the secondary structure with respect to the sensor. The measuring roller may in this case be provided with a separate drive or a drive coupled to the appliance. Measuring roller and sensor are preferably located on opposite sides of the processed metal foil section and are in particular arranged aligned with one another. According to a further configuration of the apparatus, illumination means are provided, which partially irradiate at least one side of the metal foil section in the detection field of the sensor. By way of example, there may be illumination means which are positioned on the remote side of the metal foil section and radiate through openings (opposite light) and/or illumination means which are arranged on the same side of the metal foil section as the sensor, in order to at least partially illuminate the detection field which can be seen by the sensor (incident light). The invention now also proposes a metal foil section which has been produced by a process according to the invention or using an apparatus according to the invention and which has a length of greater than 1 m, with a maximum position shift of 0.3 mm between primary structure and secondary structure. It is preferable for a maximum position shift of this type to be present over significantly greater lengths, for example over 100 m or 1000 m. The process according to the invention and the apparatus according to the invention for the first time allow production of such accurate metal foils over such a length. Therefore, such accurate metal foils can be provided even in series production, ensuring a high yield of material at a high production rate. In this context, it is particularly preferable for the metal foil section to have a thickness in the range from 30 µm (0.03 mm) to 150 µm (0.15 mm) and a secondary structure with a ratio of width to height of less than 2.0, in particular even less than 1.5. Therefore, it has proven appropriate for the apparatus and/or the process to be used for deformation of very thin, filigree structures. The width/height ratio indicates that a relatively considerable deformation of the metal foil section is realized, with in particular the regions of the corrugation peaks and corrugation valleys being very small, and therefore accurate alignment of primary structure, and secondary structure in the manner described above being advantageous. It is very particularly preferable to construct a honeycomb body using at least one metal foil section of this type. In particular in the case of honeycomb bodies of helical construction, metal foil sections of a great length have to be processed, so that in particular in this case it is appropriate to use metal foil sections of this type. The thickness indicated for the metal foil section allows the provision of a large surface area within a small volume of the honeycomb body, and the width/height ratio is responsible for slender passages which ensure good mass transfer of the flowing exhaust gas toward the (coated) walls. The invention and the technical background are explained in more detail below with reference to the figures. The figures show particularly preferred exemplary embodiments, although without the invention being restricted to these embodiments. In particular, it should be noted that the size ratios illustrated are only schematic. In the drawing: Fig. 1: diagraramatically depicts a first variant embodiment of the apparatus according to the invention; Fig. 2: diagrammatically depicts a metal foil section in the state after various treatment processes; Fig. 3: diagrammatically depicts a further illustration of a metal foil section with a correct position and an incorrect position of primary structure and secondary structure; Fig. 4: diagrammatically depicts a perspective view of the positioning of a sensor with respect to a metal foil section; Fig. 5: diagrammatically depicts the position shift of a metal foil section produced with and without control; Fig. 6: diagrammatically depicts a perspective view of a honeycomb body; and Fig. 7: diagrammatically depicts a detail of the honeycomb body from Fig. 6. Fig. 1 diagrammatically depicts the process for producing a multiply structured metal foil section 1. The following description is substantially based on the direction of advance 13, with the metal foil section 1 being unwound from a coil 24 and then passing through a first tool 3 and a second tool 4 before being examined by means of a sensor 11 and a measuring roller 16 and finally being fed to a third tool 27. The shaping of the metal foil section 1 is then concluded, so that the desired metal foil section 1 can finally be severed by means of a separation apparatus 28. The coil 24 is a type of store for metal foil which is wound up helically. The coil 24 is generally driven and has a compensation element, for example what is known as a dancer (not shown), which compensates for fluctuations in the rate of advance of the metal foil section 1, connected downstream of it. Thereafter, the metal foil section 1 is passed via a foil brake 25, which ensures sufficient tensioning by the point of the advancing drive of the metal foil section 1. The foil brake 25 is preferably a type of felt belt, which is if appropriate moved counter to the direction of advance 13. To ensure that the metal foil section 1 bears reliably against the foil brake 25, the latter may be realized by a permanent magnet (not illustrated). Under certain circumstances, it may be advantageous for the supply of the metal foil section 1 to the first tool 3 to be controlled by means of the foil brake 25 likewise as a function of the produced position of primary structure and secondary structure, which can be effected separately and/or in addition to the control by means of the profiled roller 5. The second tool 4 is designed with a pair of profiled rollers 5 rotating with a predetermined rotation angle 39 or a predetermined rotational speed. For this purpose, at least one of the shaping profiled rollers 5 is designed with an appliance 12 as its drive. This appliance 12 is also responsible for transporting the metal foil section 1 from the foil brake 25 to the first tool 3. A foil guide 26, which is responsible, for example, for perpendicular feeding of the metal foil section 1 as far as the profiled rollers 5, is provided between the first tool 3 and the second tool 4. The first tool 3 is preferably a stamping machine working on the reciprocating motion principle, the reciprocating motion of the plunger 50 being effected by means of an eccentric 48. The stamping machine ie able, for example, to introduce slots with dimensions of 2.5 x 0.8 mm into the smooth metal foil section 1. The material which is stamped out is removed by means of a suction extractor 49 located opposite. After the metal foil section 1 has then been provided with a primary structure (not illustrated here, cf. Fig. 2) by the first tool 3 and with, a secondary structure 6 by the second tool 4, it is fed to an arrangement with an optical sensor 11 which determines a spatial position of primary structure and secondary structure in a subregion 7 of the metal foil section 1. The sensor 11 is assigned a measuring roller 16 on the opposite side of the metal foil section 1, which measuring roller 16 is itself driven, the drive 51 preferably being connected via a coupling to the appliance 12 used to drive the profiled roller 5, for example via a belt (not illustrated). Moreover, illumination means 18 are positioned on the side of the sensor 11 for at least partially lighting up the subregion 7 (incident light). The image generated by the optical sensor 11 is processed in a control unit 14, which for example recognizes an incorrect position. If it recognizes an incorrect position, the control unit 14 adapts at least one operating parameter of the profiled roller 5 of the second tool 4, for example by influencing the driving appliance 12 and altering the angular velocity. • After it has left the appliance for determining the spatial position of primary structure and secondary structure, the metal foil section 1 is fed via a further foil guide 26 to a third tool 27, which likewise comprises a pair of profiled rollers 5. This third tool 27 introduces a tertiary structure (not illustrated here, cf. Pig. 2) into the metal foil section 1 before the metal foil section 1 is cut to the desired length by means of a separation apparatus 28. The process illustrated here can be used to introduce particularly complex structures into a metal foil section while at the same time ensuring a high degree of accuracy over a prolonged period of time during series production of metal foil sections of this type. Fig. 2 diagrammatically depicts a metal foil section 1 as is present in different region's of the apparatus shown in Fig. 1. From left to right in Fig. 2, it is possible to recognize first of all a smooth region, ae is present for example in the region of the foil brake 25. The metal foil section 1 is then provided with a primary structure 2, in this case slots, in the region of the first tool 3. Thereafter, as illustrated further to the right, the secondary structure 6 is introduced in the region of the second tool 4; in the variant embodiment illustrated here, the primary structure 2 is arranged on each corrugation peak 31. The secondary structure 6 is produced with a width 22, which describes the distance between two adjacent corrugation peaks 31 or corrugation valleys 32, and a predetermined height 23, the height 23 describing the distance between a corrugation peak 31 and a corrugation valley 32. After the metal foil section 1 hag left the second tool 2, a tertiary structure 29 is formed in the region of the third tool 27; in the variant embodiment illustrated, this involves a region of the metal foil section 1 between two adjacent primary structures 2 being pressed in. In this way, what is known as a microstructure is formed, which is subsequently to constitute a guide surface, projecting into a passage, for an exhaust-gas stream. Fig. 3 illustrates a metal foil section 1 (in plan view) of a predetermined length 20. The upper part of Fig. 3 reveals an accurate alignment of the openings 8 with respect to the corrugation peaks 31. In the lower part of the figure, it can be seen that the openings 8 are not accurately aligned with respect to the corrugation 9. A center 32 of the opening 8 has a position shift 10 with respect to the corrugation peak 31. The lower part of the figure also illustrates that the position shift 10 is becoming smaller from left to right, since the control has detected the incorrect position and adapted an operating parameter of the profiled roller. In this way, a correct position is achieved again after just a few corrugation peaks 31 or corrugation valleys 32. Fig. 4 diagrammatically depicts the positioning of an optical sensor 11 with respect to the metal foil section 1, which is formed with a predetermined thickness 21. As indicated diagrammatically here, the optical sensor 11 has a viewing direction 33 which describes its detection field 15. To scan different subregions of the metal foil section 1, it is possible to vary the detection field 15 with respect to the metal foil section 1. This is possible by the sensor 11 having a pivot angle 34 for pivoting the viewing direction 30 and by virtue of the fact that the sensor 11 can be moved in different directions of movement 35 relative to the metal foil section 1. In the variant embodiment illustrated, illumination means 18, by means of which the opening 8 can be detected in opposing light, are provided on the opposite side 19 of the metal foil section 1 from the sensor 11. It is preferable for a reference point determination to be carried out by means of the sensor 11 in such a way that the position of the opening 8 is detected in opposing light in a first subsection of the detection field 15, while the position of the corrugation peak 31 is detected by incident light in another subregjon of the detection field 15. Fig. 5 diagrammatically depicts a position shift 10 over the rotation angle 39 of the shaping and transporting profiled roller 5. A first curve 37 illustrates the position shift 10 as was usually established in processes known hitherto as a result of position tolerances, material inhomogeneities, etc. A first curve 3 7 of this type, as also occurs from time to time in known apparatus, is characterized in particular by periodic fluctuations which are attributable in particular to tolerances in the region of the second tool and recur with the revolutions of the profiled rollers. In the second, lower curve 38, the position shift 10 varies to only a very small extent about the abscissa (corresponding to a position shift of 0 mm). This curve 38 can be moved even closer to the abscissa if the control system is made even more dynamic. By way of example, an external fault 36 (e.g. excited vibrations) has been applied here during production. As can be seen, a relatively major position shift 10 occurs initially, but this has been compensated for again after just a short time or after a short rotational movement of the profiled roller. The preferred use of metal foil sections 1 which have been produced by the process according to the invention and/or using the apparatus according to the invention is for exhaust-gas treatment units 45 for use for purifying exhaust gases from mobile or stationary internal combustion engines. An example of an exhaust- gas treatment unit 45 of this type is illustrated in Fig. 6. The exhaust-gas treatment unit 45 comprises a housing 44 in which a honeycomb body 40 is provided. In the variant embodiment shown, the honeycomb body 4 0 is constructed with a corrugated layer 41 and a smooth layer 42, which have been wound up helically. The corrugated layer 41 has structures which are superimposed on one another; the secondary structure 6, i.e. the corrugation shape, can be seen in this end- side view. This corrugation shape forms passages 43 through which the exhaust gas can enter inner regions of the honeycomb body 40. A detail (denoted by VII) of this honeycomb body 40 is illustrated in Fig. 7. Fig. 7 shows an end-side view of the honeycomb body 40 in detail. The smooth layer 42 is realized using a filter material, while the corrugated layer 41 comprises a metal foil section 1 of the type described above. The corrugated layer 41 and the smooth layer 42 form contact locations 46, which are used, for example, to provide connections produced by a joining technique and to delimit adjacent passages 43 from one another. At at least some of these contact locations 46, the corrugated layer 41 and the smooth layer 42 are connected to one another, preferably by brazing. The walls which delimit the passages 43 and are formed by the smooth layer 42 and the corrugated layer 41 are provided with a coating 47 for catalytically converting the exhaust gases. The invention described above is suitable in particular for the production of multiply superimposed structures in a metal foil section with a high degree of precision being achieved. This allows considerable cost savings to be made with regard to the production of metal foils of this type and also allows a considerable increase in efficiency and long-term durability of honeycomb bodies constructed using metal foils of this type to be achieved. List of designations 1 Metal foil section 2 Primary structure 3 First tool 4 Second tool 5 Profiled roller 6 Secondary structure 7 Subregion 8 Openings 9 Corrugations 10 Position shift 11 Sensor 12 Appliance 13 Direction of advance 14 Control unit 15 Detection field 16 Measuring roller 17 Apparatus 18 Illumination means 19 Side 20 Length 21 Thickness 22 Width 23 Height 24 Coil 25 Foil brake 26 Foil guide 27 Third tool 28 Separation apparatus 29 Tertiary structure 30 Corrugation valley 31 Corrugation peak 32 Center 33 Viewing direction 34 Pivot angle 35 Direction of movement 36 Fault 37 First curve 38 Second curve 39 Rotation angle 4 0 Honeycomb body 41 Corrugated layer 42 Smooth layer 43 Passage 44 Housing 45 Exhaust-gas treatment unit 46 Contact location 47 Coating 48 Eccentric 49 Suction extractor 50 Plunger 51 Drive WE CLAIM 1. A process for producing structures superimposed on one another in a metal foil section (1) comprising at least the following steps; a) producing a primary structure (2) using a first tool (3); b) transferring the metal foil section (1) to a second tool (4), the second tool (4) having at least one shaping profiled roller (5) which is responsible for transferring the metal foil section (1); c) producing a secondary structure (6) using the second tool (4); d) determining a spatial position of primary structure (2) and secondary structure (6) in at least one subregion (7) of the metal foil section (1); e) detecting a position shift from primary structure to secondary structure of greater than the recommended value and adapting an operating parameter of the at least one profiled roller (5). 2. The process as claimed in claim 1, wherein the at least one profiled roller (5) is operated at an angular velocity which is altered in step e). 3. The process as claimed in claim 1 or 2 wherein at least step d) Is carried out at least once per revolution of the at least one profiled roller (5). 4. The process as claimed in one of the preceding claims, wherein step e) is carried out at least once per revolution of the profiled roller (5). 5. The process as claimed in one of the preceding claims, wherein step a) comprises the stamping of openings (8) and step c) comprises the shaping of corrugations (9) into the metal foil section (1). 6. The process as claimed in one of the preceding claims, wherein an incorrect position involves a position shift (10) from primary structure (2) to secondary structure (6) of greater than 0.3 mm. 7. The process as claimed in one of the preceding claims, wherein the detection of an incorrect position Is carried out by means of at least one optical sensor (11). 8. An apparatus (17) for producing structures which are superimposed on one another, comprising at least the following components: - a first tool (3), which is able to produce openings (8) in a metal foil section (1), - a second tool (4), which has a pair of shaping profiled rollers (5) through which a metal foil section (1) can be passed to produce corrugations (9), the pair of profiled rollers (5) being able to effect an advance of the metal foil section (1) through the first tool (3) and the second tool (4), - an appliance (12) for driving at least one profiled roller (5) of the second tool (4), - at least one optical sensor (11) which is a camera, is connected downstream of the second tool (4) as seen in a direction of advance (13), and - at least one control unit (14), which is connected to the sensor (11) and the appliance (12). 9. The apparatus (17) as claimed in claim 8, wherein the at least one sensor (11) is configured in such a way that it has a variable detection field (15). 10.The apparatus (17) as claimed in claim 8 or 9, wherein the at least one sensor (11) is assigned a measuring roller (16) which positions a metal foil section (1) with respect to the at least one sensor (11). 11.The apparatus (17) as claimed in one of claims 8 to 10, wherein illumination means (18) are provided, which radiate onto at least part of one side (19) of the metal foil section (1) in the detection field (15) of the at least one sensor (11). 12. A metal foil section (1) produced by the process as claimed in one of claims 1 to 7 or using the apparatus (17) as claimed in one of claims 8 to 11, which has a length (20) of greater than 1.0 m, with a maximum position shift (10) of 0.3 mm being present between primary structure (2) and secondary structure (6). 13.The metal foil section (1) as claimed in claim 12, which has a thickness (21) in the range from 30 µm to 150 µm and a secondary structure (6) with a ratio of width (22) to height (23) of less than 2.0. 14.A honeycomb body (40) comprising at least one metal foil section (1) as claimed in claim 12 or 13. ABSTRACT A PROCESS FOR PRODUCING STRUCTURES SUPERIMPOSED ON ONE ANOTHER IN A METAL FOIL SECTION AND AN APPARATUS FOR PRODUCING THE SAME A process for producing structures which are superimposed on one another in a metal foil section (1), comprising at least the following steps: a) producing a primary structure (2) using a first tool (3); b) transferring the metal foil section (1) to a second tool (4), the second tool (4) having at least one shaping profiled roller (5) which is responsible for transferring the metal foil section (1); c) producing a secondary structure (6) using the second tool (4); d) determining a spatial position of primary structure (2) and secondary structure (6) in at least one subreglon (7) of the metal foil section (1); e) detecting an incorrect position and adapting an operating parameter of the at least one profiled roller (5). The invention also proposes an apparatus suitable for this process and metal foils producible thereby, which are suitable for the production of catalyst support bodies that can be used in exhaust systems of internal combustion engines.

Full Text

The invention relates to a process for producing structures superimposed on one
another in a metal foil section and an apparatus for producing the same. Metal foil
sections of this type are preferably used to construct honeycomb bodies that are used,
for example, as exhaust-gas treatment components in exhaust systems of internal
combustion engines.
For the exhaust-gas treatment of mobile internal combustion engines, such as for
example spark-ignition and diesel engines, it is known to arrange at least one exhaust-
gas treatment component, which provides a relatively large surface area (such as what
Is known as a honeycomb body), in the exhaust pipe. These components are if
appropriate provided with an application-specific (e.g. adsorbing, catalytlcally active
and/or other) coating, intimate contact with the exhaust gas flowing past being realized
on account of the large surface area of the component. Examples of these components
include filter elements for filtering out particulates contained In the exhaust gas,
adsorbers for storing pollutants (e.g. NO*) contained in the exhaust gas for at least a
limited time, catalytic converters (e.g. 3-way catalyst, oxidation catalyst, reduction
catalyst, etc.), diffusors for influencing the flow of and/or swirling up the exhaust gas
flowing through or also heating elements which heat the exhaust gas to a desired
temperature in particular after an internal combustion engine cold start. The following
support substrates have fundamentally proven suitable for the conditions of use in the
exhaust system of an automobile: ceramic honeycomb bodies, extruded honeycomb
bodies and honeycomb bodies made from metal foils. In view of the fact that these
support substrates always need to be adapted to their corresponding function, high-
temperature-resistant and

corrosion-resistant metal foils represent especially
suitable starting materials for their production.
It ia known to produce honeycomb bodies using a
plurality of at least partially structured metal
sheets, which are then introduced into a housing and
thereby form a support body which can be provided with
one or more of the abovementloned coatings. The at
least partially structured metal sheets are arranged in
such a way as to form passages arranged substantially
parallel to one another. To ensure this, some of the
metal sheets are provided with a structure, for example
a type of corrugation structure, sawtooth structure,
square-wave structure, delta-wave structure, omega
structure or the like.
Furthermore, it is known to introduce a second
structure into sheet-metal foils of this type, this
second structure being intended in particular to
prevent a laminar flow, with which gas exchange between
regions of the exhaust-gas part-stream located in the
center of a passage of this type and the, for example,
catalytically active passage wall regions does not take
place to a sufficient extent, from forming immediately
after the exhaust gas has entered the honeycomb body.
This second structure or microstructure provides flow-
facing surfaces which are responsible for swirling up
the exhaust-gas part-streams in the interior of a
passage of this type. This leads to intensive mixing of
the exhaust gas part-streams themselves, thereby
ensuring intimate contact between the pollutants
contained in the exhaust gas and the passage wall.
Furthermore, it is possible to use second structures of
this type to form flow ducts running transversely to
the passage, allowing gas exchange between exhaust-gas
part-streams in adjacent passages. For this reason, it
is known to use microstmctures which comprise, for
example, guide surfaces, studs, projections, vanes,
tabs, holes or the like. In this respect, there is a

very considerable range of variation when producing
metallic honeycomb bodies of this type compared to
honeycomb bodies made from ceramic material, since such
complex passage walls cannot be realized, or can only
be realized with a particularly high level of technical
outlay, using ceramic material.
These metal sheets provided with structures are then
stacked (if appropriate alternately with smooth
interlayers between them), intertwined and inserted
into a housing, leading to the formation of a honeycomb
body which has passages that are substantially parallel
to one another.
Furthermore, in the context of exhaust-gas treatment it
is of particular interest for pollutants contained in
the exhaust gas to be converted virtually immediately
after the internal combustion engine has started up.
This should take place with a particularly high
efficiency in accordance with statutory stipulations
and guidelines. For this reason, ever thinner metal
sheets have been used in the past. These thinner sheets
provide a very low area-specific heat capacity, i.e.
relatively little heat is withdrawn from the exhaust
gas flowing past, or the temperature of the metal
sheets themselves rises relatively quickly. This is
important because the catalytically active coatings
which are currently used in the exhaust system only
start to convert the pollutants above a certain light-
off temperature, which is approximately 230°C to 270°C.
With a view to converting these pollutants with at
least a 98% efficiency after just a few seconds, metal
sheets with a thickness of, for example, less than
0.1 mm, in particular even less than 0.05 mm, are used.
However, the abovementioned objectives give rise to a
number of manufacturing technology and application-
related problems. For example, it should be noted that
under certain circumstances the targeted setting of an

exhaust gas flow profile in the honeycomb body requires
precise alignment of the microstructures in the
passages. Furthermore, it should be borne in mind that
metal foils of this type are connected to one another
by joining techniques, in particular are soldered
together (by brazing, if appropriate under a vacuum)
and/or are welded to one another. However, this
presupposes the presence of defined contact regions
between the metal foils. This in turn means that it is
necessary to ensure that the structures which are
superimposed on one another are aligned as accurately
as possible. Hitherto, it has not been possible to
ensure this with a sufficient level of accuracy. On
account of external influences involved in the
production of the structures, such as for example
vibrations excited in the metal foils, deviations occur
in the drawing and/or forming properties of the metal
foil. Manufacturing inaccuracies or tolerances within
the tools (such as for example true-running errors,
positioning errors, contour errors in rolling teeth,
etc.) lead to undesirable deviations in the positions
of the structures with respect to one another which
periodically fluctuate. Moreover, inliomogeneities in
the material used for the metal foils can lead to
further deviations in the structures with respect to
one another.
It is an object of the present invention to at least
partially alleviate the technical problems which have
been outlined in connection with the prior art. In
particular, it is intended to provide a process for
producing multiply structured metal foils of this type
which ensures that the structures which are
superimposed on one another are aligned as accurately
as possible with respect to one another. The process is
also to satisfy the demands of series production for
metal foils of this type and to represent a time-saving
and cost-saving route. Furthermore, it is intended to
provide an apparatus for producing metal foils of this

type, The metal foils produced by the process and/or the apparatus are to have a
particularly accurate alignment of the structures which are superimposed on one
another and are to be used In particular to produce durable honeycomb bodies which
can be used in the exhaust system of internal combustion engines.
These objects are achieved by the process of producing superimposed primary and
secondary structures and by the apparatus for producing the same. Further
advantageous configurations of the process and apparatus are given in the dependent
patent claims. The invention also proposes a metal foil section produced by the process
and/or the apparatus and a honeycomb body produced therefrom. The features listed
individually In the patent claims can be combined with one another in any technically
appropriate way and can be supplemented by explanatory statements from the
description, thereby demonstrating further variant embodiments of the invention.
The process according to the invention for producing structures which are
superimposed on one another in a metal foil section includes at least the following
steps:
a) producing a primary structure using a first tool;
b) transferring the metal foil section to a second tool, the second tool having at
least one shaping profiled roller which is responsible for transferring the metal
foil section;
c) producing a secondary structure using the second tool;
d) determining a spatial position of primary structure and secondary structure in at
least one subreglon of the metal foil section;

e) detecting an incorrect position and adapting an
operating parameter of the at least one
profiled roller.
It is customary for structures of this type to be
produced in a continuous process (or with a frequency
of greater than 1 advancing step per second), with the
metal foil being unrolled from a coil and fed to the
tools. Therefore, the process outlined here considers a
metal foil section which is deformed. Accordingly, the
metal foil section is initially smooth and is fed to
the first tool to produce a primary structure. The
primary structure is in this case preferably a
microstructure, i.e. for example an embossed or stamped
formation, which extends only over a small region of
the metal foil section and is intended in particular to
influence the subsequent flow of the exhaust gas in the
passage. In addition, a primary structure of this type
may also represent a preparatory measure for the
subsequent formation of (other or further)
microstructures, for example slots, at which subregions
of the metal foil are subsequently deformed so as to
produce guide surfaces or the like.
As explained in step b), the metal foil section is
transferred by a profiled roller of the second tool. In
other words, the second tool pulls the metal foil
section through the first tool. Although it is also
possible for apparatuses for clamping and/or guiding
the metal foil section to be provided upstream of the
first tool and/or between the first tool and the second
tool, the advance of the metal foil section at the
desired velocity or cycle rate is determined by the
profiled roller.
In addition to the shaping, i.e. the production of a
secondary structure (step c)), the profiled roller also
has a transporting function for the metal foil section.
Engagement of the profiled roller in the secondary

structure of the metal foil section allows a force to
be introduced parallel to the direction of advance of
the metal foil section, with the rotational speed of
the profiled roller determining the speed of advance of
the metal foil section.
After the primary structure and the secondary structure
(as well as any further structures) have been formed,
in accordance with step d) the spatial position of
these structures which are superimposed on one another
is then recorded. In this step, it is preferable to in
each case record reference points of the primary
structure and the secondary structure and to evaluate
the position of these reference points with respect to
one another. It is possible for their position with
respect to one another to be recorded in one or more
planes (parallel, perpendicular and/or oblique with
respect to the surface of the smooth metal foil
section). In particular center points and/or center
lines of the primary structure are recommended as
reference points for the primary structure. By way of
example, the extremities of the secondary structure,
such as for example the . corrugation peaks or
corrugation valleys in the case of a corrugated
structure, are recommended as reference points for the
secondary structure.
After the spatial position of primary structure and
secondary structure has been determined, their spatial
position is evaluated. In this context, it is possible
to predetermine different tolerance ranges or limit
values, which differentiate an acceptable position
(correct position) and an incorrect position from one
another. If the result of step d) is that an incorrect
position is present, at least one operating parameter
of the at least one profiled roller is then altered in
accordance with step e). A suitable operating parameter
is in particular the rotational speed of the profiled
roller, although under certain circumstances it is also

possible to carry out adaptations by varying the
position of the profiled roller with respect to other
components of the second tool, in particular a further
profiled roller. Adaptation of this nature leads to the
shaping profile of the profiled roller being realigned
with respect to the distance to the first tool, thereby
altering the position of the secondary structure in the
metal foil section relative to the primary structure.
This brings about accurate alignment of primary
structure and secondary structure. The process proposed
here allows highly dynamic control of the process for
producing metal foils of this type with structures
which are superimposed on one another, in which it is
possible to automatically react quickly to material
inhomogeneities, external disruptions or the like.
Furthermore, it is proposed that the at least one
profiled roller is operated at an angular velocity
which is altered in step e). The profiled rollers used
to produce the secondary structure have hitherto been
operated at a constant angular velocity, with one
revolution of the profiled roller if appropriate being
divided into a multiplicity of rotation angle sections
or increments and rotation continuing by a constant
number of increments at predetermined time intervals.
The present invention now departs from this procedure.
If an incorrect position is detected, a correction is
achieved by virtue of either continuing to rotate for a
selected, constant number of increments but in an
altered time interval and/or by the number of
increments being varied while maintaining a constant
time interval. In view of the fact that control of this
nature is only launched when an incorrect position is
detected, phases during which a constant angular
velocity is present may also occur during the process,
so that under certain circumstances a relatively long
period of time (for example 5 minutes) needs to be
considered with regard to a varying angular velocity.

However, it is particularly advantageous if step d) is
carried out at least once per revolution of the at
least one profiled roller. This means that a check of
the spatial position of primary structure and secondary
structure is carried out at the latest after every
revolution of the profiled roller. This has the
advantage that this control system is highly dynamic
and can also react quickly to faults, such as for
example the occurrence of vibrations.
It is also preferable if step e) is carried out at
least once per revolution of the profiled roller. It is
in this case possible for the adapting of the at least
one operating parameter of the at least one profiled
roller to be controlled in such a way that the
incorrect position is corrected at the latest after one
revolution, in particular if step d) is carried out
only after each revolution. However, for an even more
dynamic control system, it is advantageous for steps d)
and e) to be carried out a number of times per
revolution of the profiled roller in order for a
correction to take place in less than one revolution of
the profiled roller. In the latter case, steps d) and
e) are preferably carried out at least twice and in
particular at least four times per revolution of the
profiled roller.
If the position of the profiled roller with respect to
other components can be altered as operating parameter,
the configuration of the secondary structure is
altered. This means, for example, that the shaping
sections of the profiled rollers engage in one another
to a greater extent and the secondary structure is
thereby produced with a greater height. This leads to a
higher demand for material per segment of secondary
structure, so that in this way it is likewise possible
to shift the position of the primary structure and
secondary structure relative to one another. With a
view to the production of a honeycomb body, this leads

to the formation of passages with different passage
cross sections, which may be advantageous in certain
applications. However, to accurately influence the flow
properties of the exhaust gas in the honeycomb body in
this way, very accurate control of the position of the
profiled rollers is required.
According to a preferred configuration of the process,
step a) comprises the stamping of openings and step c)
comprises the shaping of corrugations into the metal
foil section. The openings may be designed as slots,
holes or the like. The corrugations are substantially
characterized by corrugation peaks and corrugation
valleys, with the openings being aligned with respect
to these corrugation peaks and corrugation valleys. In
this case, it is preferable for the spatial position of
the openings and corrugations in the direction of
advance and in a plane of the metal foil section to be
determined and adapted. Although this is a preferred
variant, it is in particular also possible for openings
to be introduced into the metal foil section by means
of a rotary stamping tool and/or a laser. In principle,
it is also possible for a plurality of primary
structures or openings to be introduced simultaneously,
so that after step a) the metal foil section has a
plurality of rows of primary structures or openings.
Furthermore, it is proposed that an incorrect position
involves a position shift from primary structure to
secondary structure of greater than 0.3 mm. This
produces a limit value used to distinguish a correct
position from an incorrect position. The position shift
is preferably considered in the direction of advance of
the metal foil section. The reference points used for
the primary structure and the secondary structure may
be their center points or center lines. If the primary
structure is formed by openings designed as slots,
their center line should be parallel to the profile of
the corrugation peaks or corrugation valleys. The

maximum position shift which is still permissible from
primary structure to secondary structure is preferably
below an absolute value of 0.2 nun, in particular below
0.1 mm.
According to a further configuration of the process,
the detection of an incorrect position ia carried out
by means of at least one optical sensor. This optical
sensor is arranged downstream of the second tool (or a
subsequent tool) and therefore observes the spatial
position of the primary structure and secondary
structure which have currently been formed. A
recommended optical sensor is in particular a camera,
the picture resolution (pixels) of which permits the
determination of a position shift. These pixels can be
used, for example, to determine the position shift and
to effect a corresponding adjustment to the angular
velocity of the at least one profiled roller.
A further aspect of the invention proposes an apparatus
for producing structures which are superimposed on one
another, comprising at least the following components:
a first tool, which is able to produce openings in
a metal foil section,
a second tool, which has a pair of shaping
profiled rollers through which a metal foil
section can be passed to produce corrugations, the
pair of profiled rollers being able to effect an
advance of the metal foil section through the
first tool and the second tool,
an appliance for driving at least one profiled
roller of the second tool,
at least one optical sensor which is connected
downstream of the second tool as seen in a
direction of advance, and
at least one control unit, which is connected to
the sensor and the appliance.

This apparatus is suitable in particular for carrying
out a process which has been described in accordance
with the invention.
In the apparatus described here, the first tool is
preferably a stamping machine which removes subregiona
of the metal foil section. The second tool is
preferably a corrugation rolling machine. Electric
motors or servomotors may be advantageous as the
appliance for driving at least one profiled roller. It
is preferable for the at least one profiled roller to
be driven with a frequency of greater than 6 Hz
[1/second], in particular greater than 8 Hz or even
12 Hz. The at least one optical sensor preferably
comprises a camera. The at least one control unit
evaluates the data from the at least one optical sensor
and determines a spatial position of primary structure
and secondary structure. Moreover, the control unit
detects an incorrect position and then adapts an
operating parameter of the appliance used to drive the
at least one profiled roller. The control unit may
comprise image recognition means, data processing
programs, memory elements and the like.
Preference is given to an apparatus in which the at
least one sensor is configured in such a way that it
has a variable detection field. This is to be
understood in particular as meaning that the detection
field can be positioned variably with respect to the
metal foil section. This preferably ensures a movement
of the detection field in the direction of advance or
perpendicular to the direction of advance, it being
possible for this movement to be realized by
translational movements and/or by pivoting of the
sensor. It is in this way also possible to record major
position shifts (as may occur for example when starting
the production process or during a material change).
Moreover, it is possible to use a single sensor to
record the reference points for the primary structure

and the secondary structure at various regions of the
metal foil section. It is in this way possible to keep
the technical outlay involved in determining the
spatial position of primary structure and secondary
structure at a low level.
Furthermore, it is proposed that the at least one
sensor is assigned a measuring roller which positions a
metal foil section with respect to the at least one
sensor. The measuring roller, which does not itself
effect any permanent deformation of the structures, but
rather is merely responsible for accurately guiding the
metal foil section, produces, for example, an accurate
alignment of the secondary structure with respect to
the sensor. The measuring roller may in this case be
provided with a separate drive or a drive coupled to
the appliance. Measuring roller and sensor are
preferably located on opposite sides of the processed
metal foil section and are in particular arranged
aligned with one another.
According to a further configuration of the apparatus,
illumination means are provided, which partially
irradiate at least one side of the metal foil section
in the detection field of the sensor. By way of
example, there may be illumination means which are
positioned on the remote side of the metal foil section
and radiate through openings (opposite light) and/or
illumination means which are arranged on the same side
of the metal foil section as the sensor, in order to at
least partially illuminate the detection field which
can be seen by the sensor (incident light).
The invention now also proposes a metal foil section
which has been produced by a process according to the
invention or using an apparatus according to the
invention and which has a length of greater than 1 m,
with a maximum position shift of 0.3 mm between primary
structure and secondary structure. It is preferable for

a maximum position shift of this type to be present
over significantly greater lengths, for example over
100 m or 1000 m. The process according to the invention
and the apparatus according to the invention for the
first time allow production of such accurate metal
foils over such a length. Therefore, such accurate
metal foils can be provided even in series production,
ensuring a high yield of material at a high production
rate.
In this context, it is particularly preferable for the
metal foil section to have a thickness in the range
from 30 µm (0.03 mm) to 150 µm (0.15 mm) and a
secondary structure with a ratio of width to height of
less than 2.0, in particular even less than 1.5.
Therefore, it has proven appropriate for the apparatus
and/or the process to be used for deformation of very
thin, filigree structures. The width/height ratio
indicates that a relatively considerable deformation of
the metal foil section is realized, with in particular
the regions of the corrugation peaks and corrugation
valleys being very small, and therefore accurate
alignment of primary structure, and secondary structure
in the manner described above being advantageous.
It is very particularly preferable to construct a
honeycomb body using at least one metal foil section of
this type. In particular in the case of honeycomb
bodies of helical construction, metal foil sections of
a great length have to be processed, so that in
particular in this case it is appropriate to use metal
foil sections of this type. The thickness indicated for
the metal foil section allows the provision of a large
surface area within a small volume of the honeycomb
body, and the width/height ratio is responsible for
slender passages which ensure good mass transfer of the
flowing exhaust gas toward the (coated) walls.

The invention and the technical background are
explained in more detail below with reference to the
figures. The figures show particularly preferred
exemplary embodiments, although without the invention
being restricted to these embodiments. In particular,
it should be noted that the size ratios illustrated are
only schematic. In the drawing:
Fig. 1: diagraramatically depicts a first variant
embodiment of the apparatus according to the
invention;
Fig. 2: diagrammatically depicts a metal foil section
in the state after various treatment processes;
Fig. 3: diagrammatically depicts a further illustration
of a metal foil section with a correct position
and an incorrect position of primary structure
and secondary structure;
Fig. 4: diagrammatically depicts a perspective view of
the positioning of a sensor with respect to a
metal foil section;
Fig. 5: diagrammatically depicts the position shift of
a metal foil section produced with and without
control;
Fig. 6: diagrammatically depicts a perspective view of
a honeycomb body; and
Fig. 7: diagrammatically depicts a detail of the
honeycomb body from Fig. 6.
Fig. 1 diagrammatically depicts the process for
producing a multiply structured metal foil section 1.
The following description is substantially based on the
direction of advance 13, with the metal foil section 1
being unwound from a coil 24 and then passing through a

first tool 3 and a second tool 4 before being examined
by means of a sensor 11 and a measuring roller 16 and
finally being fed to a third tool 27. The shaping of
the metal foil section 1 is then concluded, so that the
desired metal foil section 1 can finally be severed by
means of a separation apparatus 28.
The coil 24 is a type of store for metal foil which is
wound up helically. The coil 24 is generally driven and
has a compensation element, for example what is known
as a dancer (not shown), which compensates for
fluctuations in the rate of advance of the metal foil
section 1, connected downstream of it. Thereafter, the
metal foil section 1 is passed via a foil brake 25,
which ensures sufficient tensioning by the point of the
advancing drive of the metal foil section 1. The foil
brake 25 is preferably a type of felt belt, which is if
appropriate moved counter to the direction of advance
13. To ensure that the metal foil section 1 bears
reliably against the foil brake 25, the latter may be
realized by a permanent magnet (not illustrated). Under
certain circumstances, it may be advantageous for the
supply of the metal foil section 1 to the first tool 3
to be controlled by means of the foil brake 25 likewise
as a function of the produced position of primary
structure and secondary structure, which can be
effected separately and/or in addition to the control
by means of the profiled roller 5.
The second tool 4 is designed with a pair of profiled
rollers 5 rotating with a predetermined rotation angle
39 or a predetermined rotational speed. For this
purpose, at least one of the shaping profiled rollers 5
is designed with an appliance 12 as its drive. This
appliance 12 is also responsible for transporting the
metal foil section 1 from the foil brake 25 to the
first tool 3. A foil guide 26, which is responsible,
for example, for perpendicular feeding of the metal
foil section 1 as far as the profiled rollers 5, is

provided between the first tool 3 and the second
tool 4.
The first tool 3 is preferably a stamping machine
working on the reciprocating motion principle, the
reciprocating motion of the plunger 50 being effected
by means of an eccentric 48. The stamping machine ie
able, for example, to introduce slots with dimensions
of 2.5 x 0.8 mm into the smooth metal foil section 1.
The material which is stamped out is removed by means
of a suction extractor 49 located opposite.
After the metal foil section 1 has then been provided
with a primary structure (not illustrated here, cf.
Fig. 2) by the first tool 3 and with, a secondary
structure 6 by the second tool 4, it is fed to an
arrangement with an optical sensor 11 which determines
a spatial position of primary structure and secondary
structure in a subregion 7 of the metal foil section 1.
The sensor 11 is assigned a measuring roller 16 on the
opposite side of the metal foil section 1, which
measuring roller 16 is itself driven, the drive 51
preferably being connected via a coupling to the
appliance 12 used to drive the profiled roller 5, for
example via a belt (not illustrated). Moreover,
illumination means 18 are positioned on the side of the
sensor 11 for at least partially lighting up the
subregion 7 (incident light).
The image generated by the optical sensor 11 is
processed in a control unit 14, which for example
recognizes an incorrect position. If it recognizes an
incorrect position, the control unit 14 adapts at least
one operating parameter of the profiled roller 5 of the
second tool 4, for example by influencing the driving
appliance 12 and altering the angular velocity. •
After it has left the appliance for determining the
spatial position of primary structure and secondary

structure, the metal foil section 1 is fed via a
further foil guide 26 to a third tool 27, which
likewise comprises a pair of profiled rollers 5. This
third tool 27 introduces a tertiary structure (not
illustrated here, cf. Pig. 2) into the metal foil
section 1 before the metal foil section 1 is cut to the
desired length by means of a separation apparatus 28.
The process illustrated here can be used to introduce
particularly complex structures into a metal foil
section while at the same time ensuring a high degree
of accuracy over a prolonged period of time during
series production of metal foil sections of this type.
Fig. 2 diagrammatically depicts a metal foil section 1
as is present in different region's of the apparatus
shown in Fig. 1. From left to right in Fig. 2, it is
possible to recognize first of all a smooth region, ae
is present for example in the region of the foil brake
25. The metal foil section 1 is then provided with a
primary structure 2, in this case slots, in the region
of the first tool 3. Thereafter, as illustrated further
to the right, the secondary structure 6 is introduced
in the region of the second tool 4; in the variant
embodiment illustrated here, the primary structure 2 is
arranged on each corrugation peak 31. The secondary
structure 6 is produced with a width 22, which
describes the distance between two adjacent corrugation
peaks 31 or corrugation valleys 32, and a predetermined
height 23, the height 23 describing the distance
between a corrugation peak 31 and a corrugation valley
32. After the metal foil section 1 hag left the second
tool 2, a tertiary structure 29 is formed in the region
of the third tool 27; in the variant embodiment
illustrated, this involves a region of the metal foil
section 1 between two adjacent primary structures 2
being pressed in. In this way, what is known as a
microstructure is formed, which is subsequently to
constitute a guide surface, projecting into a passage,
for an exhaust-gas stream.

Fig. 3 illustrates a metal foil section 1 (in plan
view) of a predetermined length 20. The upper part of
Fig. 3 reveals an accurate alignment of the openings 8
with respect to the corrugation peaks 31. In the lower
part of the figure, it can be seen that the openings 8
are not accurately aligned with respect to the
corrugation 9. A center 32 of the opening 8 has a
position shift 10 with respect to the corrugation peak
31. The lower part of the figure also illustrates that
the position shift 10 is becoming smaller from left to
right, since the control has detected the incorrect
position and adapted an operating parameter of the
profiled roller. In this way, a correct position is
achieved again after just a few corrugation peaks 31 or
corrugation valleys 32.
Fig. 4 diagrammatically depicts the positioning of an
optical sensor 11 with respect to the metal foil
section 1, which is formed with a predetermined
thickness 21. As indicated diagrammatically here, the
optical sensor 11 has a viewing direction 33 which
describes its detection field 15. To scan different
subregions of the metal foil section 1, it is possible
to vary the detection field 15 with respect to the
metal foil section 1. This is possible by the sensor 11
having a pivot angle 34 for pivoting the viewing
direction 30 and by virtue of the fact that the sensor
11 can be moved in different directions of movement 35
relative to the metal foil section 1. In the variant
embodiment illustrated, illumination means 18, by means
of which the opening 8 can be detected in opposing
light, are provided on the opposite side 19 of the
metal foil section 1 from the sensor 11. It is
preferable for a reference point determination to be
carried out by means of the sensor 11 in such a way
that the position of the opening 8 is detected in
opposing light in a first subsection of the detection
field 15, while the position of the corrugation peak 31

is detected by incident light in another subregjon of
the detection field 15.
Fig. 5 diagrammatically depicts a position shift 10
over the rotation angle 39 of the shaping and
transporting profiled roller 5. A first curve 37
illustrates the position shift 10 as was usually
established in processes known hitherto as a result of
position tolerances, material inhomogeneities, etc. A
first curve 3 7 of this type, as also occurs from time
to time in known apparatus, is characterized in
particular by periodic fluctuations which are
attributable in particular to tolerances in the region
of the second tool and recur with the revolutions of
the profiled rollers. In the second, lower curve 38,
the position shift 10 varies to only a very small
extent about the abscissa (corresponding to a position
shift of 0 mm). This curve 38 can be moved even closer
to the abscissa if the control system is made even more
dynamic. By way of example, an external fault 36 (e.g.
excited vibrations) has been applied here during
production. As can be seen, a relatively major position
shift 10 occurs initially, but this has been
compensated for again after just a short time or after
a short rotational movement of the profiled roller.
The preferred use of metal foil sections 1 which have
been produced by the process according to the invention
and/or using the apparatus according to the invention
is for exhaust-gas treatment units 45 for use for
purifying exhaust gases from mobile or stationary
internal combustion engines. An example of an exhaust-
gas treatment unit 45 of this type is illustrated in
Fig. 6. The exhaust-gas treatment unit 45 comprises a
housing 44 in which a honeycomb body 40 is provided. In
the variant embodiment shown, the honeycomb body 4 0 is
constructed with a corrugated layer 41 and a smooth
layer 42, which have been wound up helically. The
corrugated layer 41 has structures which are

superimposed on one another; the secondary structure 6,
i.e. the corrugation shape, can be seen in this end-
side view. This corrugation shape forms passages 43
through which the exhaust gas can enter inner regions
of the honeycomb body 40. A detail (denoted by VII) of
this honeycomb body 40 is illustrated in Fig. 7.
Fig. 7 shows an end-side view of the honeycomb body 40
in detail. The smooth layer 42 is realized using a
filter material, while the corrugated layer 41
comprises a metal foil section 1 of the type described
above. The corrugated layer 41 and the smooth layer 42
form contact locations 46, which are used, for example,
to provide connections produced by a joining technique
and to delimit adjacent passages 43 from one another.
At at least some of these contact locations 46, the
corrugated layer 41 and the smooth layer 42 are
connected to one another, preferably by brazing. The
walls which delimit the passages 43 and are formed by
the smooth layer 42 and the corrugated layer 41 are
provided with a coating 47 for catalytically converting
the exhaust gases.
The invention described above is suitable in particular
for the production of multiply superimposed structures
in a metal foil section with a high degree of precision
being achieved. This allows considerable cost savings
to be made with regard to the production of metal foils
of this type and also allows a considerable increase in
efficiency and long-term durability of honeycomb bodies
constructed using metal foils of this type to be
achieved.

List of designations
1 Metal foil section
2 Primary structure
3 First tool
4 Second tool
5 Profiled roller
6 Secondary structure
7 Subregion
8 Openings
9 Corrugations
10 Position shift
11 Sensor
12 Appliance
13 Direction of advance
14 Control unit
15 Detection field
16 Measuring roller
17 Apparatus
18 Illumination means
19 Side
20 Length
21 Thickness
22 Width
23 Height
24 Coil
25 Foil brake
26 Foil guide
27 Third tool
28 Separation apparatus
29 Tertiary structure
30 Corrugation valley
31 Corrugation peak
32 Center
33 Viewing direction
34 Pivot angle
35 Direction of movement
36 Fault
37 First curve

38 Second curve
39 Rotation angle
4 0 Honeycomb body
41 Corrugated layer
42 Smooth layer
43 Passage
44 Housing
45 Exhaust-gas treatment unit
46 Contact location
47 Coating
48 Eccentric
49 Suction extractor
50 Plunger
51 Drive

WE CLAIM
1. A process for producing structures superimposed on one another in a metal foil
section (1) comprising at least the following steps;
a) producing a primary structure (2) using a first tool (3);
b) transferring the metal foil section (1) to a second tool (4), the second tool
(4) having at least one shaping profiled roller (5) which is responsible for
transferring the metal foil section (1);
c) producing a secondary structure (6) using the second tool (4);
d) determining a spatial position of primary structure (2) and secondary
structure (6) in at least one subregion (7) of the metal foil section (1);
e) detecting a position shift from primary structure to secondary structure of
greater than the recommended value and adapting an operating
parameter of the at least one profiled roller (5).

2. The process as claimed in claim 1, wherein the at least one profiled roller (5) is
operated at an angular velocity which is altered in step e).
3. The process as claimed in claim 1 or 2 wherein at least step d) Is carried out at
least once per revolution of the at least one profiled roller (5).
4. The process as claimed in one of the preceding claims, wherein step e) is carried
out at least once per revolution of the profiled roller (5).
5. The process as claimed in one of the preceding claims, wherein step a)
comprises the stamping of openings (8) and step c) comprises the shaping of
corrugations (9) into the metal foil section (1).

6. The process as claimed in one of the preceding claims, wherein an incorrect
position involves a position shift (10) from primary structure (2) to secondary
structure (6) of greater than 0.3 mm.
7. The process as claimed in one of the preceding claims, wherein the detection of
an incorrect position Is carried out by means of at least one optical sensor (11).
8. An apparatus (17) for producing structures which are superimposed on one
another, comprising at least the following components:

- a first tool (3), which is able to produce openings (8) in a metal foil section (1),
- a second tool (4), which has a pair of shaping profiled rollers (5) through which a
metal foil section (1) can be passed to produce corrugations (9), the pair of
profiled rollers (5) being able to effect an advance of the metal foil section (1)
through the first tool (3) and the second tool (4),
- an appliance (12) for driving at least one profiled roller (5) of the second tool
(4),
- at least one optical sensor (11) which is a camera, is connected downstream of
the second tool (4) as seen in a direction of advance (13), and
- at least one control unit (14), which is connected to the sensor (11) and the
appliance (12).
9. The apparatus (17) as claimed in claim 8, wherein the at least one sensor (11) is
configured in such a way that it has a variable detection field (15).
10.The apparatus (17) as claimed in claim 8 or 9, wherein the at least one sensor
(11) is assigned a measuring roller (16) which positions a metal foil section (1)
with respect to the at least one sensor (11).

11.The apparatus (17) as claimed in one of claims 8 to 10, wherein illumination
means (18) are provided, which radiate onto at least part of one side (19) of the
metal foil section (1) in the detection field (15) of the at least one sensor (11).
12. A metal foil section (1) produced by the process as claimed in one of claims 1 to
7 or using the apparatus (17) as claimed in one of claims 8 to 11, which has a
length (20) of greater than 1.0 m, with a maximum position shift (10) of 0.3 mm
being present between primary structure (2) and secondary structure (6).
13.The metal foil section (1) as claimed in claim 12, which has a thickness (21) in
the range from 30 µm to 150 µm and a secondary structure (6) with a ratio of
width (22) to height (23) of less than 2.0.
14.A honeycomb body (40) comprising at least one metal foil section (1) as claimed
in claim 12 or 13.

ABSTRACT

A PROCESS FOR PRODUCING STRUCTURES SUPERIMPOSED ON ONE
ANOTHER IN A METAL FOIL SECTION AND AN APPARATUS FOR PRODUCING
THE SAME
A process for producing structures which are superimposed on one another in a metal
foil section (1), comprising at least the following steps:
a) producing a primary structure (2) using a first tool (3);
b) transferring the metal foil section (1) to a second tool (4), the second tool (4)
having at least one shaping profiled roller (5) which is responsible for
transferring the metal foil section (1);
c) producing a secondary structure (6) using the second tool (4);
d) determining a spatial position of primary structure (2) and secondary structure
(6) in at least one subreglon (7) of the metal foil section (1);
e) detecting an incorrect position and adapting an operating parameter of the at
least one profiled roller (5).
The invention also proposes an apparatus suitable for this process and metal foils
producible thereby, which are suitable for the production of catalyst support bodies that
can be used in exhaust systems of internal combustion engines.

A PROCESS FOR PRODUCING STRUCTURES SUPERIMPOSED ON ONE ANOTHER IN A METAL FOIL SECTION AND AN APPARATUS FOR PRODUCING THE SAME

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