Metal deforming – By use of 'flying tool' engaging moving work – Included in plural deforming stations or passes
Reexamination Certificate
1999-04-30
2001-09-11
Larson, Lowell A. (Department: 3725)
Metal deforming
By use of 'flying tool' engaging moving work
Included in plural deforming stations or passes
C072S379600
Reexamination Certificate
active
06286353
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a process for producing at least one structured metal sheet, a process for producing a laminated metal sheet pack and an apparatus for producing structured metal sheets. Such metal sheets are processed primarily to constitute honeycomb bodies for catalytic converters which are used in particular in motor vehicle exhaust gas systems. Such a honeycomb body is described, for example, in European Patent 0 245 737 B1.
Structured metal sheets are generally produced in the state of the art by shaped rollers which mesh with each other and which preferably have an involute tooth configuration or a tooth configuration of a similar construction. However, other geometries for the structures, for example a trapezium shape, a zig-zag shape, etc., are also known.
Portions are cut off the structured strip-shaped metal sheet and stacked to form a metal sheet pack, with a smooth sheet being inserted between the structured metal sheets. The ends of the stack are, for example, twisted in mutually opposite directions around at least two fixed points. The stack when deformed in that way is fitted into a tubular casing. The tubular casing, with the metal sheet stack fitted therein, is then subjected to a brazing operation in which the tubular casing with the metal sheet stack and the individual sheets are brazed together. The tubular casing and the metal sheet stack have different coefficients of thermal expansion. In order to ensure that a satisfactory brazed connection is produced between the metal sheets in relation to each other, and between the metal sheets and the tubular casing, it has already been proposed that the metal sheet pack be fitted into the tubular casing in a prestressed condition so that no gap formation occurs between the metal sheets and/or between the metal sheets and the tubular casing. In the case of honeycomb bodies which are wound in a spiral shape, it has already been proposed that radial depressions should be provided in the structured metal sheet at apex regions of the structure. The material serving for the welding or brazing operation can be disposed in the depressions.
The strip-shaped metal sheet experiences deformation during the structure-forming step. There are fluctuations in the height of the structure of the structured metal sheet due to fluctuations in the material properties of the metal sheet. Those fluctuations in the height of the structure are due to the fact that the elasticity of the metal sheet lies within a tolerance band. Tolerances with respect to the shaped rollers may possibly also be superimposed on that effect, so that there is no guarantee that metal sheet packs can always be fitted into a tube under the same prestressing. It has also been found that the cell density of a honeycomb body may also be different, with the same production process.
European Patent Application 0 279 159 A1, corresponding to U.S. Pat. No. 4,845,073, discloses a process for producing at least one structured metal sheet, wherein the structure is formed by inter-engaging toothed rollers.
European Patent Application 0 490 611 A1 also discloses a process and an apparatus for producing welded laminated metal sheets and packs of metal sheets.
European Patent Application 0 460 611 A1 discloses a structure-providing step through the use of which a first metal sheet is provided with a structure by using shaped rollers. A second, smooth metal sheet, is then applied to the structured sheet and the first and second metal sheets are passed through a second pair of rollers.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a process for producing at least one structured metal sheet, a process for producing a laminated metal sheet pack and an apparatus for producing structured metal sheets, which overcome the hereinafore-mentioned disadvantages of the heretofore-known processes and apparatuses of this general type and which ensure that, upon further processing of the structured metal sheets, or the metal sheet pack to constitute a honeycomb body, fluctuations in prestressing with which a metal sheet pack can be fitted into a tubular casing are slight. A further aim of the invention is to ensure that a honeycomb body which is formed by structured metal sheets has a constant cell density.
With the foregoing and other objects in view there is provided, in accordance with the invention, a process for producing at least one structured metal sheet, which comprises initially subjecting a strip-shaped metal sheet to a structure-forming step, forming a structure with a structure height greater than a desired structure height; and thereafter subjecting the metal sheet to a calibration step by applying a force to the structure of the metal sheet, causing the height of the structure to correspond to the desired structure height after the calibration step.
The fact that, during the structure-forming step, the height of the structure is greater than a desired or reference height ensures that the height of the structure of the metal sheet is sufficiently great, in spite of a spring-back effect. In addition any tolerances in shaped tools are compensated. The calibration step involves applying a force to the apex regions of the structure by which the structure is deformed so that after the calibration step the height of the structure corresponds to the reference height.
In accordance with another mode of the invention, during the structure-forming step the metal sheet is passed between two inter-engaging shaped tools, preferably between two meshing shaped tools.
In accordance with a further mode of the invention, the overall shaped height of the shaped tools, in particular the shaped rollers, is preferably greater than the desired structure height. If the shaped tools are formed as shaped rollers, the shaped rollers may be rollers with an involute profile, for example.
In accordance with an added mode of the invention, the calibration step preferably takes place in such a way that the metal sheet with the structure is passed through a gap having a gap height which is smaller than the desired structure height of the metal sheet or corresponds to the desired structure height of the metal sheet. In accordance with an additional mode of the invention, a gap of this kind can preferably be formed by configuring two rollers with their axes disposed in parallel relationship.
In accordance with yet another mode of the invention, in order to ensure that a honeycomb body which is produced from a structured metal sheet or a pack of metal sheets has a constant cell density, after the calibration step the spring property of the structure of the metal sheet is determined. A blank length is ascertained in consideration of the spring property, and a portion is cut off the strip-shaped metal sheet corresponding to the blank length. A structured metal sheet which is produced in this way allows a honeycomb body to be produced which has a reproducible cell density, and the metal sheets can be used in a tubular casing with reproducible prestressing.
In accordance with yet a further mode of the invention, the blank length which is ascertained is used as a measurement for further portions.
In accordance with another concept according to the invention, there is proposed a process for producing a laminated metal sheet pack, as is known, for example, from European Patent 0 45 737 B1.
Accordingly, with the objects of the invention in view, there is also provided a process for producing a laminated metal sheet pack, which comprises initially subjecting a first strip-shaped metal sheet to a structure-forming step, forming a structure in the first metal sheet having a structure height greater than a desired structure height; thereafter subjecting the structure to a calibration step by applying a force to the structure of the first metal sheet, causing the height of the structure to correspond to the desired structure height after the calibration step; and placing a second strip-shaped metal sheet, preferably a smooth metal s
Emitec Gesellschaft fuer Emissions-technologie mbH
Greenberg Laurence A.
Larson Lowell A.
Lerner Herbert L.
Stemer Werner H.
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