Title of Invention

A PROCESS FOR PRODUCING ALUMINIUM CONTAINING HONEYCOMB BODIES

Abstract

Disclosed is a method for production aluminium-containing honeycomb bodies (1), comprising the following steps : at least partly structured aluminium-based metal films are selected; at least partly structured metal films (2) are stacked and/or rolled so as to form a honeycomb structure (3) encompassing channels (5); the metal film (2) is heated from the open face (26) of the channels (5) with the aid of at least one radiant heater (8), the honeycomb structure being heated in at least one subarea in such a way that said at least one subarea (9) has a temperature ranging between about 450°C and about 600°C after approximately 2 to approximately 30 seconds; the metal films (2) are joined together in the at least one subarea (9) by means of a joining technique

Full Text

Process for producing aluminum-containing hineycomb bodies using radiant heators The present invention relates to a process for producing aluminum-containing honeycomb bodies, in which at least partially structured metal foils are stacked and/or wound to form a honeycomb structure with passages running approximately parallel to an axis, these metal foils are at least partially introduced into a tubular casing and are connected to one another by a joining technique at least in subregions. Metallic honeycomb bodies of this type are used, for example, as catalyst support bodies for the purification of an exhaust gas from an internal combustion engine. Known honeycomb bodies, in particular metallic catalyst support bodies, have a honeycomb structure with, for example, thin-walled, smooth and/or corrugated sheet- metal foils which are wound helically or in an S shape and, in a circularly cylindrical or oval-cylindrical tubular casing, are connected to one another by a joining technique such as welding, soldering, sintering, adhesion bonding or the like. To increase the stability of a honeycomb body of this type under fluctuating thermal stresses, it is already known for the sheet-metal foils of the honeycomb structure to be connected to one another by a joining technique only in certain subregions, for example at the end sides, and if appropriate also to be connected to the tubular casing, so that in the event of thermal stresses occurring, the tubular casing and honeycomb structure are able to expand unimpeded, with the result that fluctuating plastic deformations of the honeycomb structure, leading to destruction and detachment of the honeycomb structure, are avoided. Furthermore, processes for the end-side connection by a ioininq technique of a honeycomb structure arranged in a tubular casing are known in which the connection by a joining technique is carried out in a discontinuous process which lasts for a number of hours in a high- temperature furnace. The individual honeycomb bodies are in this case introduced into the furnace in batches. To avoid chemical reactions, such as, for example, undesirable formation of crystals or oxidation in particular at the surface of the sheet-metal foils, the joining process is carried out in the furnace under a shielding gas atmosphere containing, for example, argon and/or hydrogen or in vacuo. This in particular leads to a relatively high outlay on apparatus, with correspondingly high costs. Furthermore, there are known continuous processes which use induction coils to produce a connection between the sheet-metal foils by a joining technique. The induction coils are used to heat, at least subregions, in which a connection of the sheet-metal foils by a joining technique is ultimately to be produced, so that, for example, a solder arranged in the subregions begins to flow and, after cooling, generates a connection of this type. Depending on the form of the connection by a joining technique, the induction coils have to be operated with different AC voltage frequencies and have to be moved relatively close to the corresponding subregions of the honeycomb body. This can lead to an uneven formation of connections by a joining technique in the respective subregions. Working on this basis, it is an object of the present invention to provide a process for producing honeycomb bodies which allows processing of metal foils containing aluminum and which is suitable in particular for continuous production, with an improved quality of the connections by a joining technique that can be produced. These objects are achieved by the process having the features of claim 1. Further advantageous configurations of the process are described in the dependent claims. The process according to the invention for producing metallic honeycomb bodies comprises the following steps: selecting at least partially structured metal foils based on aluminum; stacking and/or winding at least partially structured metal foils to form a honeycomb structure with passages, heating the metal foils with the aid of at least one radiant heater from the open end face of the passages, the honeycomb structure, at least in a subregion, being heated in such a way that the at least one subregion, after approximately 2 seconds to approximately 30 seconds, is at a temperature of approximately 450°C to approximately 600°C; connecting the metal foils to one another by a joining technique in the at least one subregion. In the text which follows, a metal foil based on aluminum is to be understood as meaning a metal foil which contains at least 90% by weight of aluminum. The aluminum content is advantageously on average at least approx. 95% by weight or even at least approx. 99% by weight. Under certain circumstances, it may even be necessary to select metal foils with an even higher aluminum content, for example more than 99.9% by weight aluminum. Unless specifically stated otherwise, in the text which follows the term "metal foil" is always used to refer to an aluminum-containing metal foil of this type. In addition, the metal foil may include at least one of the following chemical components: manganese (Mn), silicon (Si), magnesium (Mg), copper (Cu), titanium (Ti), iron (Fe). By way of example, the following metal foils can be used: AA3005 (Al Mn 1 Mg 0.5); AA3003 (Al Mn 1 Cu) ; AA3103 (Al Mn 1); and AA 8001 (Al Fe Si) Surprisingly, tests have shown that relatively high heating rates can be achieved with honeycomb bodies of this type. For example, it is possible, using suitable heat sources, as described below, for the metal foils to be heated to the desired temperature wthin just, two seconds. It is in this way possible to achieve extremely short production cycles. If, for example, the configuration of the contact zones between the metal foils or with a tubular casing surrounding them is not completely uniform, however, it may also be necessary to perform slightly slower heating, so that the desired temperature range is only reached after 15 to 30 seconds. Furthermore, only certain conditions should be used, since increased oxidation of the surface of the metal foils is then observed, making further uniform introduction of heat considerably more difficult. According to the invention, the temperature is approximately between 450°C and 600°C. In this context, what solder is used if appropriate to form a connection by a joining technique between the metal foils is of crucial importance. If, for example, a zinc-based solder is used, under certain circumstances temperatures of only approx. 450°C to approximately 530°C will be sufficient, in which case shorter heat-up times are preferably also required. However, if the metal foils are connected to one another for example using a solder based on aluminum/silicon, temperatures from approx. 560°C to approx. 600°C need to be set, in which case longer heating times may need to be used. In particular in the case of the latter solders, it is accordingly necessary to carry out heating up to temperatures which are only just below the melting point of the metal foil itself. In particular, the temperatures are in a range which is less than 70°C, in particular less than 50°C or even less than 3 0°C below the melting point of the metal foils which are to be connected to one another. On account of the short heat-up time to these high temperatures and a targeted heating of predeterminable subregions, the result is a very efficient and energy-saving method. This also has the advantage that. the proposed process is suitable in particular for the series production or mass production of metallic honeycomb bodies. Furthermore, it is proposed that radiant heaters which generate a targeted infrared heating radiation are used to heat the honeycomb structure, generating a clear temperature drop in the vicinity of the outside of the at least one subregion. The spatially very tightly restricted introduction of heat on account of the substantially parallel infrared heating radiation leads to a very uniformly distributed thermal energy and therefore to very uniform formation of connections within the heated subregions. Consequently, the process according to the invention produces metallic honeycomb bodies which have high-quality connections between the metal foils formed by a joining technique, with this heating process being of only a short duration. According to a further configuration of the process, the honeycomb structure has passages running approximately parallel to an axis, the heating radiation being directed onto an end side of the honeycomb structure in such a manner that the honeycomb structure is heated only in subregions with an axial depth which is less than the axial length of the passages. This allows the production of honeycomb bodies whose metal foils are, for example, connected to one another only in the vicinity of the end side, with in particular a thermally induced compensating expansion of the metal foils with respect to one another being ensured. In this context, the term end side is to be understood as meaning the surface in which the end faces of the passages are substantially arranged. in which the metal foils, prior to heating, are at least partially introduced into a tubular casing, are connected to one another by a joining technique, and are then completely inserted into the tubular casing, and a number of the metal foils are connected to the tubular casing by a joining technique. It is in this case possible, for example, to use different radiant heaters, in which case, at least during the connection of the metal foils to one another, a relatively homogenous distribution of the heat capacity in the subregions is ensured. Therefore, a radiant heater with a somewhat lower energy can be used for this connection than subsequently during the generation of the connection between tubular casing and honeycomb structure. According to a further configuration of the process, prior to the heating, the metal foils are completely introduced into the tubular casing, with the tubular casing preferably projecting beyond the end sides of the honeycomb structure. This has the advantage that, after the connections by a joining technique have been formed, the metal foils no longer have to be moved relative to the tubular casing. According to yet another configuration of the process, the metal foils, prior to heating, are arranged on the outside of an inner tube, in such a way that the metal foils form passages running substantially transversely to the inner tube, with a number of metal foils being connected to the inner tube by a joining technique. Therefore, the invention also provides, for example, a process for producing honeycomb bodies through which fluid can flow in a radial direction, in which process the inner tube in particular has openings, through which the inner tube, which has incoming flow centrally, allows a gas to flow out into the radially outwardly directed passages, or vice versa. It is particularly advantageous for adjacent sections of the tubular casing or the inner tube to be heated simultaneously, if appropriate with the aid of inductively acting heating. It is in this way also possible to produce a connection by a joining technique between a number of metal foils and the tubular casing or the inner tube, with the result that the production of connections by a joining technique both between the metal foils and from metal foils to the tubular casing or inner tube is carried out in one process step, thereby in particular reducing the manufacturing time. In this context, however, it should be taken into account that the heat-up times required to reach a defined temperature may have to be lengthened if the tubular casing or inner tube is also to be heated. This is caused in particular by the different heat capacities of the metal foils and the tubular casing or inner tube. According to yet another configuration of the process, the at least one end side of the honeycomb structure is completely heated to a predeterminable depth. This leads to complete end-side connection of metal foils, preventing, for example, ends of the metal foils arranged at the end side from being made to vibrate on account of pressure fluctuations occurring in an exhaust-gas stream, since such vibrations could cause adjacent connections formed by a joining technique to become detached on account of mechanical fatigue stresses. Accordingly, the formation of connections between the metal foils by a joining technique over the entire end side of the honeycomb structure for example increases the service life of a honeycomb body used as a catalyst support body in an exhaust system. If the honeycomb structure has passages running approximately parallel to an axis, according to a further configuration of the process, the depth of the heated subregions is varied, with heating preferably being carried out to a greater depth in subregions of the honeycomb structure which are arranged radially outward than in subregions which are arranged radially inward. With regard to a configuration of a honeycomb body through which medium can flow in the radial direction, of course, a correspondingly varying depth in the axial direction and/or circumferential direction of the honeycomb body is also possible. It is in this way possible, for example, to achieve a more stable connection between the honeycomb body and the tubular casing or inner tube than the connections between the metal foils formed by a joining technique. According to a further configuration of the process, the heating radiation impinges on the at least one end side of the honeycomb structure at an angle of between 10° and 80°. The angle selected in this case has effects on the depth up to which the honeycomb structure is heated. At angles of less than 10°, the heating radiation extends over a relatively large subregion of the end side, with the result that the thermal energy generated by the radiant heater is distributed over larger subregions, thereby reducing the introduction of energy per unit area and slowing the heating process. Angles of greater than 80° should likewise be avoided, since in this case a large proportion of the heating radiation or thermal energy passes directly through the honeycomb structure and cannot be used to heat the metal foils. Furthermore, the external shape of the end side should be taken into account when selecting the angle. If this comprises, for example, a telescopic arrangement of metal foils, in which adjacent metal foils are arranged partially offset with respect to one another, by way of example relatively large or relatively small angles should be used depending on the type of telescopic arrangement, whereas if the end side is substantially planar, angles in a range from 30° to 60° are preferred According to yet another configuration of the process, the honeycomb body is moved relative to the at least one radiant heater during the heating operation, with the result that, with the aid of a radiant heater which emits a spatially limited heating radiation, if appropriate even large subregions of the honeycomb structure, in particular the entire end side of the honeycomb structure, are heated. According to a process variant, it is proposed to execute a rotational relative movement of the at least one radiant heater about the axis of the honeycomb body, thereby likewise ensuring a large-area and uniform heating of the honeycomb structure. It is preferable for the relative movement between honeycomb body and the at least one radiant heater to be generated by the honeycomb body rotating about its axis and/or the angle between the radiation axis of the at least one radiant heater and the axis of the honeycomb body being varied. This ensures that the heating radiation penetrates down to the desired depth of the honeycomb structure irrespective of whether the subregions to be heated are located close to a projecting tubular casing or in centrally arranged subregions of the end side. According to yet another configuration of the process, the connections by a joining technique are produced by soldering, sintering and/or diffusion welding. It is in this case particularly advantageous for solder, diffusion promoter or the like to be arranged in the subregions prior to the heating used to form the connections by a joining technique. It is preferable for the connections produced by a joining technique to be formed by soldering, in which case solder is arranged in the subregions prior to the heating operation. As a result, the temperatures which are required to form the connection produced by a joining technique are kept at a relatively low level, so that relatively short cycle times for the formation of the connections can be maintained. If particularly high temperatures (in particular higher than 550°C) occur during the production of the connection by a joining technique, it is advantageous for these connections to be produced under shielding gas. Known shielding gases, in particular with an argon content, are suitable for this purpose. In the text which follows, the process according to the invention is described in more detail in conjunction with an apparatus which is suitable for carrying out the process. The apparatus for producing metallic honeycomb bodies, in particular for carrying out the process according to the invention, comprises a positioning surface for positioning a honeycomb body during a heating operation, and at least one radiant heater with a radiation axis. The apparatus is distinguished by the fact that the positioning surface and the radiation axis of the radiant heater include an angle of from 10° to 80°. In this case, the radiant heater is in particular configured in such a way that it radiates at an angle of 10° to 80° with respect to the end side of a honeycomb body fixed on the positioning surface. The radiant heater allows rapid heating of subregions of the honeycomb body to form connections produced by a joining technique. To ensure that subregions of the honeycomb body are heated as uniformly as possible, the positioning surface is preferably pivotable, so that the angle is adjustable, in particular even during the heating operation. This can also be achieved by a further configuration of the apparatus in which the at least one infrared radiant heater is pivotable. In the apparatus, the distance between the positioning surface and the at least one infrared radiant heater can be varied. It is in this context particularly advantageous for the at least one infrared radiant heater to be movable on predeterminable paths with respect to the positioning surface. It is in this way possible to ensure, for example, that the connections produced by a joining technique are generated over a varying depth in different subregions of the heated end side. With a view to superimposing a plurality of relative movements of honeycomb body and the at least one infrared radiant heater, it is particularly advantageous for these movements to be adapted to one another, in particular by the individual movements being recorded by metre-logical means and/or coordinated by means of a common, preferably computer-controlled control unit. The positioning surface also has, for example, holding means for fixing the honeycomb body. This ensures that a desired positioning of the honeycomb body with respect to the at least one infrared radiant heater is maintained. Holding means of this type are important in particular if the positioning surface is part of an assembly line. An assembly line of this type allows the production of metallic honeycomb bodies in a continuous process, which is particularly suitable on account of the short heat-up times of the honeycomb body effected by means of the infrared radiant heaters. Moreover, it is possible to provide mirrors for diverting or reflecting the heating radiation. This is to be understood in particular as meaning parts of the heating radiation which have already been reflected by the metal foils. Accordingly, the use of mirrors of this type leads to improved utilization of the heating radiation generated by the infrared radiant heaters. However, it is also possible for radiation to be radiated directly onto the mirrors and in this way diverted onto the subregions to be heated, in which case, for example, projections or shoulders projecting into the direct radiation axis in the vicinity of the end side of the honeycomb body can be "bypassed". If the connections produced by a joining technique are produced at very high temperatures, the apparatus has means for generating a local shielding gas atmosphere, in particular a housing. In this case, the housing encloses at least sections close to the subregion of the honeycomb body which is heated with the aid of the infrared radiant heaters, in which case impeding of the direct heating radiation should be avoided. The process will now be explained in more detail on the basis of the following drawings. However, the explanations presented in this context in this respect do not constitute any restriction of the invention. In the drawing: fig. 1 shows an embodiment of a honeycomb body which has been produced, fig. 2 shows an embodiment of a production apparatus, and fig. 3 shows a second embodiment of a production apparatus. Figure 1 shows a diagrammatic and perspective illustration of an aluminum-containing honeycomb body 1 with stacked metal foils 2 which have been wound in an S shape. The honeycomb body 1 has passages 5 which are formed using smooth and corrugated metal foils 2. The passages 5 and the metal foils 2 form a corresponding honeycomb structure 3. The honeycomb structure 3 is surrounded by a tubular casing 6 which projects beyond the end sides 7 of the honeycomb body 1. The individual, open end faces 26 of the passages 5 are in this case arranged substantially in the planar end sides 7 of the honeycomb body 1. The production of the aluminum-containing honeycomb body 1 illustrated comprises, for example, the following steps: selecting at least partially structured metal foils based on aluminum; stacking and S-shaped winding at least partially structured metal foils to form a honeycomb structure 3 with passages 5 running approximately parallel to an axis 4 (not shown); completely introducing the metal foils 2 into the tubular casing 6, with the tubular casing projecting beyond the end sides 7 of the honeycomb structure 3 ; completely heating an end side 7 of the honeycomb structure 3 with the aid of at least one radiant heater 8 (not shown), with the heating radiation being directed onto the open end faces 26 of the passages 5, in such a manner that the honeycomb structure 3, in a subregion 9 with an axial depth 10 (shorter than the axial length 11 of the passages 5), is heated in such a way that this subregion 9 is at a temperature of approximately 450°C to approximately 600°C after only approximately 2 seconds to approximately 3 0 seconds; connecting the metal foils 2 to one another and the radially 13 outer regions of the metal foils 2 to the tubular casing 6 by a joining technique, the connection produced by a joining technique being effected by soldering. Figure 2 shows a diagrammatic and perspective illustration of a first embodiment of an apparatus for producing metallic, aluminum-containing honeycomb bodies 1. The apparatus has a positioning surface 16 for positioning a honeycomb body 1 during a heating operation and an infrared radiant heater 8 with a radiation axis 15. The radiation axis 15 and the end side 7 of the honeycomb body 1, which is approximately parallel to the positioning surface 16, at least at times include an angle 14 of from 10° to 80°. The honeycomb body 1 is in this case fixed by means of holding means 19. The distance 17 from the infrared radiant heater 8 to the point at which the heating radiation impinges on the end side 7 of the honeycomb body 1 is to be selected in such a way as to ensure that the honeycomb structure 3 is heated to the predetermined depth 10 as quickly as possible. It is in this context particularly advantageous for the infrared radiant heater 8 to be moved on a path 18 relative to the honeycomb body 1, preferably with the angle 14 being varied. The path 18 is illustrated in the shape of a circle, but in particular any desired path 18 can be generated using a computer-controlled movement. For improved utilization of the heating radiation, the apparatus has a mirror 21, which throws any reflected heating radiation back onto the honeycomb structure 3. Since very rapid heating of subregions of the honeycomb body 1 is possible in this way, this type of formation of connections by a joining technique is recommended for use as a continuous process. The positioning surface 16 in this case forms part of an assembly line 22. Figure 3 shows a second embodiment of an apparatus for producing a metallic honeycomb body 1 through which medium can flow in the radial direction. The honeycomb body 1 in this case has a plurality of layers of structured and smooth metal foils 2, which form passages 5 running substantially transversely with respect to a centrally arranged inner tube 27, or radially outward. The honeycomb body 1 is fixed relative to the positioning surface 16 using holding means 19, with the honeycomb body extending through the positioning surface 16. The honeycomb body 1 is surrounded by a housing 22, which serves in particular to form a shielding gas atmosphere in the interior. For this purpose, by way of example, argon-containing shielding gas is fed into the interior of the central inner tube 27 from an end side 7 of the honeycomb body 1 by means of a nozzle 22 and emerges again from the open end faces 26 of the passages 5, with the connections produced by a joining technique being formed in a shielding gas atmosphere using the infrared radiant heater 8. For this purpose, the housing has openings 24 which ensure unimpeded heating of the honeycomb structure 3 along the radiation axis 15. In this context, the arrow 25 indicates that the honeycomb body 1 rotates for example during the heating operation, in which case the radiant heater 8 preferably radiates onto the end side 7 of the honeycomb body 1 at different angles 14 within a range from 10° to 80°. Uniform heating and therefore also a high-quality connection by a joining technique are ensured in this way. Furthermore, the embodiment illustrated offers the possibility of double-sided and simultaneous heating of both end sides 7 of the honeycomb body 1. The production times for an aluminum-containing honeycomb body 1 of this type could be further reduced in this way. List of designations 1 Honeycomb body 2 Metal foil 3 Honeycomb structure 4 Axis 5 Passage 6 Tubular casing 7 End side 8 Radiant heater 9 Subregion 10 Depth 11 Length 12 Section 13 Radius 14 Angle 15 Radiation axis 16 Positioning surface 17 Distance 18 Path 19 Holding means 2 0 Assembly line 21 Mirror 22 Housing 23 Nozzle 24 Opening 2 5 Arrow 1. A process for producing aluminum-containing honeycomb bodies (1), comprising the following steps: selecting at least partially structured metal foils based on aluminum; stacking and/or winding at least partially structured metal foils (2) to form a honeycomb structure (3) with passages (5), heating the metal foils (2) with the aid of at least one radiant heater (8) from the open end face (26) of the passages (5), the honeycomb structure (3), at least in a subregion (9), being heated in such a way that the at least one subregion (9), after approximately 2 seconds to approximately 3 0 seconds, is at a temperature of approximately 450°C to approximately 600°C; connecting the metal foils (2) fee one another by a joining technique in the at least one subregion (9). 2. The process as claimed in claim 1, in which radiant heaters which generate a targeted infrared heating radiation are used to heat the honeycomb structure (3), generating a clear temperature drop in the vicinity of the outside of the at least one subregion (9). 3. The process as claimed in claim 1 or 2, in which the honeycomb structure (3) has passages (5) running approximately parallel to an axis (4), the heating radiation being directed onto an end side (7) of the honeycomb structure (3) in such a manner that the honeycomb structure (3) is heated only in subregions (9) with an axial depth (10) which is less than the axial (4) length (11) of the passages (5). 4. The process as claimed in one of claims 1 to 3, in which the metal foils (2), prior to heating, are at least partially introduced into a tubular casing (6), are connected to one another by a joining technique, and are then completely inserted into the tubular casing (6), and a number of the metal foils (2) are connected to the tubular casing by a joining technique. 5. The process as claimed in claim 4, in which the metal foils (2) are completely introduced into the tubular casing (6), with the tubular casing (6) preferably projecting beyond the end sides (7) of the honeycomb structure (3). 6. The process as claimed in either of claims 1 and are arranged on the outside of an inner tube (27), in such a way that the metal foils (2) form passages (5) running substantially transversely to the inner tube (27), with a number of metal foils (2) being connected to the inner tube (27) by a joining technique. 7. The process as claimed in one of claims 4 to 6, in which the sections (12) of the tubular casing (6) or of the inner tube (27) which adjoin subregions (9) of the honeycomb structure (3) are additionally heated inductively. 8. The process as claimed in one of claims 1 to 7, in which the at least one end side (7) of the honeycomb structure (3) is completely heated to a predeterminable depth (10). 9. The process as claimed in one of claims 1 to 8, in which the honeycomb structure (3) has passages (5) running approximately parallel to an axis (4), and in which the depth (10) of the heated subregions (9) is varied, with heating preferably being carried out to a greater depth (10) in subregions (9) of the honeycomb structure (3) which are arranged radially (13) outward than in subregions (9) which are arranged radially (13) inward. 10. The process as claimed in one of claims 1 to 9, in which heating radiation impinges on the at least one end side (7) at an angle (14) of between 10° and 80°. 11. The process as claimed in one of claims 1 to 10, in which the honeycomb body (1) is moved relative to the at least one radiant heater (8) during the heating operation. 12. The process as claimed in claim 11, in which a rotational relative movement of the at least one radiant heater (8) takes place about the axis (4) of the honeycomb body (1). 13. The process as claimed in claim 11 or 12, in which the honeycomb body (1) rotates about its axis (4). 14. The process as claimed in one of claims 11 to 13, in which the angle (14) between the radiation axis (15) and the axis (4) of the honeycomb body (1) is varied. 15. The process as claimed in one of claims 1 to 14, in which the connections by a joining technique are produced by soldering, sintering and/or diffusion welding. 16. The process as claimed in claim 15, in which, prior to the heating used to form the connections by a joining technique, solder, diffusion promoter or the like is arranged in the subregions (9). 17. The process as claimed in one of claims 1 to 16, in which the connections by a joining technique are produced under shielding gas. Disclosed is a method for production aluminium-containing honeycomb bodies (1), comprising the following steps : at least partly structured aluminium-based metal films are selected; at least partly structured metal films (2) are stacked and/or rolled so as to form a honeycomb structure (3) encompassing channels (5); the metal film (2) is heated from the open face (26) of the channels (5) with the aid of at least one radiant heater (8), the honeycomb structure being heated in at least one subarea in such a way that said at least one subarea (9) has a temperature ranging between about 450°C and about 600°C after approximately 2 to approximately 30 seconds; the metal films (2) are joined together in the at least one subarea (9) by means of a joining technique

Documents:

561-KOLNP-2006-FORM 27.pdf

561-KOLNP-2006-FORM-27.pdf

561-kolnp-2006-granted-abstract.pdf

561-kolnp-2006-granted-claims.pdf

561-kolnp-2006-granted-correspondence.pdf

561-kolnp-2006-granted-description (complete).pdf

561-kolnp-2006-granted-drawings.pdf

561-kolnp-2006-granted-examination report.pdf

561-kolnp-2006-granted-form 1.pdf

561-kolnp-2006-granted-form 18.pdf

561-kolnp-2006-granted-form 2.pdf

561-kolnp-2006-granted-form 3.pdf

561-kolnp-2006-granted-form 5.pdf

561-kolnp-2006-granted-gpa.pdf

561-kolnp-2006-granted-reply to examination report.pdf

561-kolnp-2006-granted-specification.pdf

561-kolnp-2006-granted-translated copy of priority document.pdf