MXPA99002034A - Method and device for making a metal corrugated sheet provided with a microstructure transverse to the corrugation - Google Patents

Abstract

A device for making a metal corrugated sheet (1) of a first prescribed height is disclosed which comprises, transverse to the corrugation or in an angle relative to the corrugation, a microstructure (6, 7) of a second height (B) much lower than the first one, encompassing a device (2a, 2b) for making same, a pair of corrugating rollers in gear (3a, 3b) located behind the microstructure making device (2a, 2b) and provided on their external surfaces with recesses (8) of such size and in such arrangement as to be capable of receiving the microstructures (6, 7) so that, during the metal sheet corrugating process, said microstructures are not distorted by the corrugating rollers (3a, 3b).

Description

METHOD AND APPARATUS FOR MAKING A CORRUGATED METALLIC SHEET PROVIDED WITH A TRANSVERSAL MICRESTRUCTURE TO THE CORRUGATION Description of the Invention The invention relates to a method and devices for manufacturing a corrugated metal sheet having a prescribed first ripple height, being that transversely to the ripple or at an angle with respect to the ripple, the sheet has a microstructure with a second substantially lower ripple height. Such metal sheets are mainly produced in honeycomb bodies for catalytic converters, such as those used in particular in the exhaust gas installations of motor vehicles. However, the invention is not limited to this use, by virtue of which, for example, applications in heat exchangers are also possible. The details regarding the shape and advantages of such microstructures are described, for example, in patent documents WO 90/08249 or WO 96/09892. As is already the case in the state of the art, a microstructure in a corrugated sheet means a structure which has a substantially lower height than the undulation of the sheet. In particular, a microstructure may protrude on one side or both sides of a sheet, and this, for example, by at least 15 μ or by 0.01 up to about 0.3 times the height of the corrugation of the sheet. In the state of the art, corrugated metal sheets are generally manufactured by corrugating cylinders that mesh with one another, which preferably have a gear of evolvents or a gear of similar shape. However, other forms of corrugation are also known, for example in the form of a trapezoid, in the form of a zig-zag, etc. In a honeycomb body traversed by an exhaust gas stream, in particular in a catalytic converter, the microstructures that develop transverse or inclined with respect to the direction of the current, known as transverse structures (TS design), produce a better thermal transition between the exhaust gas and the honeycomb body, and an improvement of the diffusion processes, which are important for the catalytic effectiveness of the honeycomb body. Accordingly, it is envisaged in the state of the art to arrange the microstructures spaced at specific distances one behind the other in the direction of flow, in particular at distances of less than 20 mm, especially smaller than 10 mm. By virtue of the fact that the microstructures were relatively small in relation to the typical thickness of the sheets for honeycomb bodies, until now it had been considered that they did not bother to a great extent the subsequent production process, so that for the conformation of the honeycomb body an elaboration was made in conventional corrugating cylinders with subsequent known manufacturing steps. However, it has been shown that when corrugating a sheet that already has microstructures, these microstructures are partially crushed again, this also happens irregularly depending on the gap between one and the other of the corrugating cylinders. In order to compensate for this effect, in the case of this manufacturing method, the microstructures were first to be manufactured with a greater height of the corrugation than was desired as a final result. The cold deformations that were presented with it were already very difficult to achieve without damage in the case of some starting materials. With the sheets that are becoming thinner and an always lower ripple height, this problem becomes more acute. In the meantime, honeycomb bodies have to be produced with, for example, 77.5 cells per cm2. { cpsi = (500) cells per square inch) or more, since laminates whose thickness is even less than 30 μm are also used, increasing technical production difficulties arose. Therefore, the task of the present invention is to create a manufacturing method and a corresponding device with which corrugated metal sheets can be manufactured with microstructures that develop transverse or inclined with respect to the undulation, economically and without a deformation in Inadmissible cold For the solution of this task, a device according to claim 1 is used as well as a method according to claim 9. Advantageous improvements are indicated in the respective subordinate claims. The device according to the invention for the manufacture of a sheet of corrugated metal having a prescribed first ripple height, being that transversely to the ripple or at an angle with respect to the ripple the sheet has a microstructure with a second height of substantially smaller undulation, comprises a device for producing the microstructure, a pair of corrugating cylinders that mesh with each other which are arranged behind the device to produce the microstructure, the cylinders on their outer surfaces having recesses that are arranged in an adapted manner and / or which are large enough to accommodate the microstructures, so that the microstructures are not deformed by the corrugating cylinders when the metal sheet is corrugated. Although the manufacture of a pair of corrugating cylinders of this kind is relatively expensive, particularly for inclined development structures, the fact is that, nevertheless, the definitive advantage is obtained that, without the need to resort first to a very strong cold deformation which is subsequently partially crushed again due to the corrugation process, microstructures can be manufactured with an exactly defined height and which remains the same on all sides. Therefore, a device of this kind can also be used without problems in particular also for the manufacture of microstructures in layers of corrugated sheet with a thickness of, for example, 25 to 50 μm. Typically, corrugating cylinders with a kind of involute gear are used, although the invention is not limited to this type of cylinders. In general, all types of corrugator cylinders have a certain clearance between one another, due to which spaces can appear only on the flanks and / or on the teeth heads, or in the spaces between the teeth. They can reproduce with much difficulty during the production process. In the corrugating cylinders provided with recesses in accordance with the invention, this clearance has no influence on the height of the microstructures. It is particularly simple to shape the recesses in the form of grooves that in width and depth must correspond at least to the width and height of the microstructures. However, it is also possible to reshape the microstructures by suitably deformed grooves. In the case of the device according to the invention it is also important that the device for the production of the microstructure and the corrugating cylinders can be adjusted in such a way with respect to each other, that the microstructures produced always fall into recesses of the corrugating cylinders . The simplest way to achieve this is by means of a very close spatial arrangement, but nevertheless it can also be achieved by means of suitable adjustment devices in the case of larger spaces. Typically the honeycomb bodies are formed by alternating layers of flat and corrugated sheets, or by alternate layers of sheets with different corrugations, various forms of construction being known, for example layers of spirally wound sheets, interlaced in the shape of or intertwined in the manner of an involute. If you have to weld with one another such superimposed sheet layers, then, depending on its height, the microstructures can eventually cause clogged spaces between the layers of sheet. However, the interstices that due to the microstructures are created between the adjacent sheet layers are very difficult to overcome by welding from a certain size, so that occasionally the microstructures on the ridges of the corrugations on both sides may be undesirable. of the layers of corrugated sheet. For this case a particular embodiment of the device according to the invention provides that following the corrugating cylinders follow at least one smoothing device which can again smooth the microstructures on the crests of the corrugations of the corrugated sheet, by unilateral crushing or bilateral. Such a device can be, for example, a recessed corrugating cylinder that rotates against a flat cylinder. In this way, only the microstructures on the ridges of the corrugations are crushed, where in any case they would have no influence on the current that will later flow through the honeycomb body, whereby the connection by welding is substantially facilitated. The remaining microstructures remain unchanged and can perform their intended function without further obstruction of the course of production. Instead of the corrugating cylinders with the straightening device arranged next, alternatively it is also possible to use special corrugating cylinders which do not have recesses in the valleys of their corrugations, so that the microstructures can be crushed there. This can be achieved particularly effectively if the corrugating cylinders only have a reduced clearance between the crests of the corrugations and the valleys of the corrugations facing each other. The method according to the invention for manufacturing a corrugated metal sheet comprising a microstructure consists of the following steps: a) Produce a microstructure in a sheet that is not yet corrugated; b) Conducting the metal sheet towards a pair of corrugating cylinders that mesh with each other, which have recesses disposed longitudinally with respect to the microstructures, for the housing of the microstructures; c) Corrugation of the sheet strip without crushing the microstructures.

As explained above, by means of this procedure defined microstructures are formed, which after their formation are no longer deformed and therefore can be produced in a very defined and reproducible manner. In order to avoid the interstices between adjacent sheet layers which must be joined by welding them together, it is possible to crush the microstructures in the corrugations of the corrugations of at least one of both sides in the corrugating cylinders or in the smoothing device that follows. The examples of preferred embodiments of the invention and their advantages are explained below in greater detail on the basis of the drawing. They show: Figure 1 schematically a corrugating device according to the invention, and Figure 2 schematically the development of the production according to the invention. In figure 1 the nodal part of the present invention is represented, namely a corrugator device for metal sheets. A sheet 1 of metal which was previously provided with microstructures 6 pointing downwards and microstructures 7 pointing upwards in a device for producing microstructures, is fed to a pair of corrugating cylinders 3a, 3b. On its surface, these corrugating cylinders have recesses 8 which, in particular, are formed in the form of grooves. These recesses 8, of which only one is shown in the drawing, house the microstructures 6, 7 previously produced, so that they are not affected by the corrugation process when the sheet is corrugated. This results in a corrugated sheet with a first height A of the corrugation, which has wave peaks 9, 10 on the upper side and the lower side. The microstructures 6, 7 have a height B substantially lower than the first height A of the corrugation of the first corrugated sheet 1. In figure 2 the development of the production for the manufacture of a corrugated sheet with microstructures is represented in schematic form. The metal sheet 1 first passes through a device 2a, 2b for the production of the microstructure, such as those known from the prior art. In particular it can be cylindrical cylinders with corresponding surface structures or narrow individual discs placed in a row next to one another, which by cold deformation impose the microstructure on the metal sheet 1. This is then fed to a pair of corrugating cylinders 3a, 3b, such as those shown in more detail in figure 1. For the case where the microstructures on wave crests 9, 10 of the corrugated sheet 1 are undesirable, these can be smoothed by smoothing devices 4a, 4b or 5a, 5b. Such smoothing devices are constituted, for example, by a cylindrical cylinder 4a or 5b of smooth surface which rotates against a corrugating cylinder 4b or 5a, these corrugating cylinders preferably also having such recesses as those used for the production of the corrugated. Corrugated sheets manufactured in this way, provided with microstructures can find their application in particular for honeycomb bodies in exhaust gas installations. They increase the heat transition between the honeycomb body and a fluid whose current passes through it, and accelerate the diffusion processes, which in particular is favorable for the effectiveness of the catalytic converter.

List of reference symbols Metal sheet 2a, 2b Device to produce the microstructure 3a, 3b Pair of corrugating cylinders 4a, 4b Straightening device, below 5a, 5b Straightening device, top 6 Microstructure protruding downwards 7 Microstructure protruding upwards 8 8 Recess, slot in the corrugating cylinder 9 Cylinder gear, down 10 Cylinder gear, up A Amplitude of the ripple

Claims (1)

1. CLAIMS Device for manufacturing a corrugated metal sheet having a prescribed first ripple height, being that transversely to the ripple or at an angle with respect to the ripple, the sheet has a microstructure with a second substantially lower ripple height, characterized by a. a device for the production of the microstructure; b. a pair of corrugating cylinders that mesh with one another, which are arranged behind the device for the production of the microstructure; c. being that on its external surfaces the corrugating cylinders have recesses that are arranged in an adapted manner and that are large enough to accommodate the microstructures, so that the microstructures are not deformed by the corrugating cylinders when the metal sheet is corrugated. Device according to claim 1, characterized in that the corrugating cylinders have a gear similar to an involute gear. Device according to claim 1 or 2, characterized in that the corrugating cylinders have grooves as recesses that develop in the direction of the circumference or inclined with respect to it, which in width and depth correspond at least to the width and height of the microstructures. Device according to claim 1, 2 or 3, characterized in that the device for the production of the microstructure and the corrugating cylinders can be adjusted in such a way with respect to each other, that the microstructures produced always enter the recesses of the corrugating cylinders. Device according to one of the preceding claims, characterized in that after the corrugating cylinders there is arranged at least one smoothing device that can once again crush the microstructures unilaterally or bilaterally on the corrugations of the wave of the corrugated sheet. Device in accordance with the claim 5, characterized in that the smoothing device has a corrugating cylinder with recesses and a flat cylinder that rotates against it. Device according to one of claims 1 to 4, characterized in that the corrugating cylinders have no recesses in the valleys of their waves, so that it is possible to crush the microstructures there. Device according to claim 7, characterized in that the corrugating cylinders have a slight clearance between the wave valleys and the wave crests they face. Method for manufacturing a sheet of corrugated metal having a first prescribed ripple height, being that transversely to the ripple or at an angle with respect to the ripple, the metal sheet has a microstructure with a second ripple height substantially smaller, characterized by the following steps: a) Produce a microstructure in a sheet that is not yet corrugated; b) Conducting the metal sheet to a pair of corrugating cylinders that mesh with each other, which have recesses disposed longitudinally with respect to the microstructures, for the housing of the microstructures; c) Corrugation of the sheet strip without crushing the microstructures. Method according to claim 9, characterized in that a crushing of the microstructures on the wave crests is carried out on at least one of the two sides of the metal sheet.