Title of Invention

PROCESS FOR PRODUCING AT LEAST ONE STRUCTURED METAL SHEETS AND APPARATUS THEREFOR

Abstract

The invention relates to process for producing at least one structured metal sheet wherein a metal sheet (6) in strip form is firstly subjected to a structure-forming step by which there is formed a structure (8) whose structure height (H) is greater than a desired structure height (SH), and thereafter a calibration step in a calibration unit (9), the structure (8) being passed through between two rollers (10, 11) of the calibration unit (9) whereby the height of the structure downstream of the calibration unit (9) corresponds to the desired structure height (SH).

Full Text

1A The invention relates to a process for producing at least one structured metal sheet and apparatus therefor a process for producing a laminated metal sheet pack and an apparatus for producing structured metal sheets. Metal sheets of that kind are processed primarily to constitute honeycomb bodies for catalytic converters as are used in particular in motor vehicle exhaust gas systems. Such a honeycomb body is described for example in EP 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 design. Other geometries for the structures, for example a trapezium shape, a zig-zag shape, etc., are however also known. Portions are cut off the structured metal sheet in strip form and stacked to form a metal sheet pack or set, with a smooth sheet being inserted between the structured metal sheets. The end 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 welding operation in which the tubular casing with the metal sheet stack and the individual sheets are welded together. The tubular casing and the metal sheet stack have different coefficients of thermal expansion. In order to ensure that a satisfactory welded connection is produced as 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 is fitted into the tubular casing in a prestressed condition so that no gap formation occurs between the metal sheets and/or 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 the apex regions of the structure, in which depressions the material serving for the welding or brazing operation can be disposed. During the structure-forming step the metal sheet in strip form experiences deformation. Due to fluctuations in the material properties of the metal sheet, there are fluctuations in the height of the structure of the structured 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 in respect of 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 2 body may also be different, with the same production process. On the basis thereof, the invention is based on the problem of providing a process for producing at least one structured metal sheet and a laminated metal sheet pack and an apparatus for producing structured sheets, which ensure that, upon further processing of the structured metal sheets, or the metal sheet pack to constitute a honeycomb body, fluctuations in a 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. The process according to the invention for producing at least one structured metal sheet is distinguished in that a metal sheet in strip form is firstly formed with a structure in a structure-forming step. During the structure-forming step, a structure is produced whose structure height is greater than a reference structure height which the structured metal sheet is to have, as a finished product. The structure-forming step is followed by a calibration step in which a force is applied to the structure of the metal sheet in such a way that after the calibration step the height of the structure corresponds to the reference height of the structure. The fact that, during the structure-forming step, the height of the structure is greater than a 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 to the apex regions of the structure a force by which the structure is deformed so that after the calibration step the height of the structure corresponds to the reference height. To produce a structure during the structure-forming step, the metal sheet is passed through between two meshing shaped rollers. In that respect the overall shaped height of the shaped rollers is greater than the reference height of the structure. The shaped rollers may be for example rollers with an involute profile. The calibration step is preferably effected in such a form that the metal sheet, with the structure, is passed through a gap whose height is less than the reference height of the structure of the metal sheet or corresponds to the reference height of the structure of the metal sheet. Such a gap can be formed by two rollers being arranged with their axes parallel. In order to ensure that a honeycomb body which is produced from a structured metal sheet or a metal sheet pack enjoys a constant cell density, it is proposed that the spring property of the structure of the metal sheet is determined after the calibration step. Having regard to the spring property, a blank length is ascertained and a portion of a metal 3 sheet corresponding to the blank length is cut off the metal sheet in strip form. A structured metal sheet produced in that way can be used to produce a honeycomb body which has a reproducible cell density and the metal sheets can be fitted into a tubular casing, with a reproducible level of prestressing. 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 EP 0 245 737, in which a first metal sheet in strip form is firstly subjected to a structure-forming step by which the first metal sheet is formed with a structure whose height is greater than the reference structure height, and thereafter a calibration step in which a force is applied to the structure of the first metal sheet, such that after the calibration step the height of the structure corresponds to a reference structure height, and thereafter a second metal sheet in strip form is laid onto the first metal sheet. During the structure-forming step, the first metal sheet in strip form is passed through between two meshing shaped rollers. Alternatively it is proposed that the second metal sheet is laid onto the metal sheet prior to the calibration step. That operation provides that the structured metal sheet is calibrated jointly with the second, preferably smooth metal sheet. After the calibration step, the spring property of the structure of the first metal sheet or the spring property of the laminated metal sheets is ascertained and, having regard to the spring property, a blank length is ascertained and the first metal sheet or the laminated metal sheets are cut off, in accordance with the blank length. In accordance with a further concept according to the invention there is proposed an apparatus for producing structured metal sheets comprising a structure-imparting unit for forming a structure with a structure height, in which the structure-imparting unit which has at least two interengaging shaped tools with an overall shaped height which is greater than the reference structure, and a calibration unit arranged at a downstream position as considered in the direction of transportation movement of the metal sheet and by which a force is applied to the structure of the metal sheet such that the height of the structure corresponds to a predetermined reference structure height. The structure-imparting unit has at least two meshing shaped rollers which preferably have an involute profile. The use of rotatable shaped rollers permits a continuous production operation for a structured metal sheet. Alternatively, for the sequential production of a structure in a metal sheet, it is possible to use a structure-imparting unit comprising two shaped tools which are movable towards each other and between which the 4 metal sheet is deformable. In accordance with a further advantageous development of the invention it is proposed that the calibration unit has at least two calibration tools, between which the metal sheet can be brought, and the calibration tools define a gap whose height is less than the shaped height of the shaped tools. The gap height preferably corresponds to the reference height of the structure that a structured metal sheet is to have. The gap height is preferably adjustable by displacement of the calibration tools. The calibration tools are preferably formed by two rollers which are arranged with their axes in substantially parallel relationship. The rollers are preferably so disposed that the axes of the rollers extend substantially transversely to the direction of transportation movement of a metal sheet. In accordance with a further advantageous development of the apparatus it is proposed that arranged downstream of the calibration unit are a measuring unit by which the spring property of the metal sheet is ascertained, and a severing unit by which the metal sheet is cut to length, in accordance with the spring property thereof. Further advantages and features of the invention are described by means of the accompanying embodiments illustrated in the/drawing in which: Figure 1 diagrammatically shows a first embodiment of an apparatus for producing structured metal sheets, Figure 2 shows a calibration unit, and Figure 3 shows a second embodiment of an apparatus for producing structured sheets. Figure 1 diagrammatically shows an apparatus for producing structured sheets. The apparatus has a structure-imparting unit 1. The structure-imparting unit 1 includes two meshing shaped rollers 2, 3. The shaped rollers 2, 3 are for example of an involute shape. The axes 4, 5 of the shaped rollers 2, 3 extend in mutually parallel relationship. A metal sheet 6 in strip form which is unwound from a coil 7 runs between the shaped rollers 2, 3. While it is passing through the structure-imparting unit 1 a structure 8 is imparted to the metal sheet 6. The structure 8 substantially corresponds to the profile shape of the shaped rollers 2, 3. As considered in the direction of transportation movement of the metal sheet 6, a calibration unit 9 is arranged downstream of the structure-imparting unit 1. The calibration unit 9 has two calibration tools which are in the form of two rollers 10, 11. The rollers 10, 11 are arranged with their axes in parallel relationship. The peripheral surfaces of the rollers 10, 11 define a gap 12 through which the structured metal sheet 6 is passed. A measuring unit 13 and a severing unit 14 are arranged downstream of the calibration unit 9. 5 The spring property of the structure 8 of the metal sheet 6 is determined by the measuring unit 13. Having regard to the spring property of the structure 6, a blank or cutting length L is ascertained, and a portion 15 corresponding to the blank length L is cut off the metal sheet 6 in strip form, in the severing unit 14. The operation of ascertaining the spring property of the structure 6 of the metal sheet can be effected by a force/travel measurement procedure. The profile shape of the shaped rollers 2, 3 is such that the height H of the structure 8 is greater than a predetermined reference structure height SH. A structure 8 as is shown for example in Figure 2 is imparted to the metal sheet 6. The metal sheet when structured in that way is passed through the gap 12 between the rollers 10, 11. The height h of the gap 12 is such that the structure 8 is compressed when the metal sheet 6 passes through between the rollers 10, 11, whereby downstream of the calibration unit 9 the structure 8' is of a height which corresponds to the reference structure height SH. The rollers 10, 11 are mounted rotatably. Preferably the gap height h is adjustable by means of displaceable rollers 10, 11. Reference will now be made to the view of an apparatus as shown in Figure 3. The apparatus illustrated in Figure 3 has a structure-imparting unit 1 which is formed by two shaped rollers 2, 3 which are arranged at a spacing from each other and with their axes in parallel relationship?--As considered in the direction of transportation movement the unit 1 is followed by a calibration unit 9 which in turn is followed by a measuring unit 13 and a severing unit 14. The calibration unit 9 is formed by two rollers 10, 11 which are arranged at a spacing from each other with their axes arranged in parallel relationship. The rollers 10, 11 are mounted rotatably. The peripheral surfaces of the rollers 10, 11 define a gap 12. A metal sheet 6 in strip form is unwound from a coil 7 and fed to the structure-imparting unit 1. A structure 8 is imparted to the metal sheet 6 in the structure-imparting unit 1 by the shaped rollers 2, 3. The structure 8 is of a height H which is greater than the reference structure height SH. The metal sheet 6 when structured in that way is then fed to the calibration unit 10, The metal sheet 6 passes through the gap 12 between the rollers 10, 11. The gap 12 is of a height h which is smaller than the height H of the structure 8. While the metal sheet 6 is passing through the calibration unit 9 a force is applied to the structure 8, by which the height of the structure is set to the reference structure height SH. Upstream of the calibration unit 9, a smooth metal sheet 16 which is unwound from a coil 17 is fed onto the structured sheet 6. The smooth metal sheet 16 and the structured metal sheet 8 jointly pass through the 6 calibration unit 9. The calibration unit 9 is followed by a measuring unit 13 by which the spring property of the smooth and the structured metal sheets 6, 16 is ascertained. A blank or cutting length L is determined on the basis of the ascertained spring property. A severing unit 14 following the measuring unit 13 cuts off a portion (8) of the smooth metal sheet 16 and the structured metal sheet 6. The structured sheets 6 are stacked one upon the other, thereby producing a metal sheet pack 19 which after a twisting operation can be fitted into a tubular casing. 7 Liat of reference 1 structure-imparting unit 2,3 shaped roller 4,5 axis 6 metal sheet 7 coil 8,8' structure 9 calibration unit 10,11 roller 12 gap 13 measuring unit 14 severing unit 15 portion 16 smooth sheet 17 coil 18 portion 19 metal sheet pack 12 -8- We Claim: 1. A process for producing at least one structured metal sheet (6), comprising the steps of -providing a strip-shaped metal sheet (6); -passing the metal sheet (6) between two inter-engaging shaped rollers (2,3) to form a periodic structure (8) having an initial height (H), characterized in that the metal sheet (6) is calibrated by applying a force to the metal sheet (6) to cause the periodic structure (8) to have a desired height (SH) being less than the initial height (H). 2. The process as claimed in 1, wherein the shaped rollers (2,3) have an overall shaped height greater than the desired structure height (SH). 3. The process as claimed in 1, wherein said step of passing the metal sheet comprises passing the metal sheet (6) through two meshing shaped rollers (2,3) during the step of forming the periodic structure (8). 4. The process as claimed in 1, wherein said step of passing the metal sheet comprises passing the metal sheet (6) through a gap(12) having a gap height(h) being smaller than the desired structure height (SH) of the metal sheet (6). 5. The process as claimed in 4, wherein said gap (12) formed by two rollers (10, 11) having parallel axes (4,5). 6. A process as claimed in one of claims 1 to 5 wherein after calibration step the spring property of the structure of the metal sheet (6) is determined, in consideration of the spring property a blank length (L) is ascertained, and a portion (15, 16) is cut off the metal sheet (6) in strip form, corresponding to the blank length (L) 7. A process as claimed in claim 8, wherein the blank length (L) is used as a measurement in respect of additional portions. 8. A process for producing a laminated metal sheet (6) pack, with a plurality of structured metal sheet as claimed in claim 1, the process comprising the steps of: providing a first strip-shaped metal sheet (6); passing the first metal sheet (6) between two inter-engaging shaped rollers (2,3) to form a periodic structure (8) having an initial height (H); calibrating the first metal sheet (6) by applying a force to the first metal sheet (6) to cause the periodic structure (8) to have a desired height (SH) being less than the initial height, and -9-placing a second strip-shaped metal sheet (16) onto the first metal sheet (6). 9. The process as claimed in 8, wherein the second strip-shaped metal sheet (16) is a smooth metal sheet (6). 10. A process for producing a laminated metal sheet (19) pack, with a plurality of structured metal sheet as claimed in claim 1, the process comprising the steps of: - providing a first strip-shaped metal sheet (6); - passing the first metal sheet (6) between two inter-engaging shaped rollers (2, 3) to form a periodic structure (8) having an initial height (H); - calibrating the first metal sheet (6) by applying a force to the first metal sheet (6) to cause the periodic structure (8) to have desired height ( SH) being loss than the initial height (SH) being less than the initial height, characterized in that a second strip-shaped metal sheet ( 16) being placed on to the first metal sheet (6) prior to said calibration step. 11. An apparatus for producing structured metal sheets (6), carrying out the method as claimed in any of the preceding claims, comprising: - a structure-imparting unit (1) having at least two inter-engaging shaped rollers (2,3) for forming a periodic structure (8) having an initial height(H) in a metal sheet (6) moving in a given running direction: and ' -a calibration unit (9)disposed downstream of said structure-imparting unit (1) in said given running direction, for applying a force to said structure (8) of the metal sheet (6) causing the periodic structure (8) to have a desired height (SH) being less than the initial height (H). 12. The apparatus as claimed in claim 11, wherein said shaped rollers(2,3) have a given profile height (SH), said calibration unit (9)has at least two calibration tools (10,11) for receiving the metal sheet (6) therebetween, and said calibration tools (10, 11) define a gap (12) having a gap height (h)smaller than said given profile height (SH). 10. 13. The apparatus as claimed in claim 12, wherein said calibration tools are two rollers (10, 11) with parallel axes. 14. The apparatus as claimed in claim 12, wherein said gap height (2) of said calibration unit (9) is adjustable. 15. Apparatus as claimed in one of claims 1 l to 44, wherein downstream of the calibration unit (9) are provided a measuring unit (13) by which the spring property of the metal sheet (6, 16) is ascertained and a severing unit (14) by which the metal sheet ( 6, 16) is cut to length in accordance with the spring property. OF L.S.DAVAR & CO APPLICANTS' AGENT Dated this 21st day of October 1997 The invention relates to process for producing at least one structured metal sheet wherein a metal sheet (6) in strip form is firstly subjected to a structure-forming step by which there is formed a structure (8) whose structure height (H) is greater than a desired structure height (SH), and thereafter a calibration step in a calibration unit (9), the structure (8) being passed through between two rollers (10, 11) of the calibration unit (9) whereby the height of the structure downstream of the calibration unit (9) corresponds to the desired structure height (SH).

Documents:

01978-cal-1997-abstract.pdf

01978-cal-1997-claims.pdf

01978-cal-1997-correspondence.pdf

01978-cal-1997-description(complete).pdf

01978-cal-1997-drawings.pdf

01978-cal-1997-form-1.pdf

01978-cal-1997-form-2.pdf

01978-cal-1997-form-3.pdf

01978-cal-1997-form-5.pdf

01978-cal-1997-pa.pdf

01978-cal-1997-priority document(other).pdf

01978-cal-1997-priority document.pdf

1978-CAL-1997-FORM-27.pdf

1978-cal-1997-granted-abstract.pdf

1978-cal-1997-granted-claims.pdf

1978-cal-1997-granted-correspondence.pdf

1978-cal-1997-granted-description (complete).pdf

1978-cal-1997-granted-drawings.pdf

1978-cal-1997-granted-examination report.pdf

1978-cal-1997-granted-form 1.pdf

1978-cal-1997-granted-form 2.pdf

1978-cal-1997-granted-form 3.pdf

1978-cal-1997-granted-form 5.pdf

1978-cal-1997-granted-letter patent.pdf

1978-cal-1997-granted-others.pdf

1978-cal-1997-granted-pa.pdf

1978-cal-1997-granted-priority document.pdf

1978-cal-1997-granted-reply to examination report.pdf

1978-cal-1997-granted-specification.pdf

1978-cal-1997-granted-translated copy of priority document.pdf