Previous metal catalyst substrates have been made of individual metal foil segments and stacked to form a “herringbone” configuration, and bonded at the joints of the layers to form the stacked foil layers. One problem with this type of construction is that the bonded joints between the stacked herringbone foil layers are subject to failure when subjected to Noise, Vibration and Harshness (NVH), especially during operation or during Hot Shake conditions.
The method of manufacturing fan folded metal catalyst substrates as described in the preceding section generally requires a manual alignment and placement of the cut and stacked foil layers into the bonding fixture, which is both time consuming and difficult. In addition the foil layers can become disoriented by flipping over during the cut operation causing nesting of the corrugated layers. Layers can be missed from the stack, or layers may be out of sequential order. In addition, current cut and stack methods require a corrugated foil to be special spooled onto two spools and then one spool is required to be rewound in the reverse direction for the herringbone configuration pattern to stack up. The pieces of fan folded metal catalyst subtrates are cut and manually stacked to form the desired pattern, and the entire assembly is then placed in a weld fixture to join the layers together into an integral structure. It is understood that the current cut and stack/fold method as is difficult to fully automate, especially with regard to the alignment of the folded metal catalyst substrate layers into the desired pattern and placement of the folded metal catalyst substrate layers into a weld fixture.
It has been found that a continuous sheet of metal catalyst foil arranged in a fan fold configuration according to at least one embodiment of the present disclosure, can provide for as many various geometries as the stack layer methods set forth above for forming a fan folded metal catalyst substrate. In addition, it has been found that such an arrangement eliminates the problem of positioning the cut foil during stacking, keeping the proper alignment of the foil layers during bonding, minimizes irregular patterns seen in the cut and stack method due to foil layer position shifts that may occur during processing and improved exhaust gas flow through. The disclosed methods also lend themselves to full automation of the manufacturing process, thereby reducing costs and improving consistency as between each fan folded methal catalyst substrate made using the method of the instant application.
Certain technical and manufacturing advantages may be realized by implementing the embodiment(s) as described. For example, a continuous sheet of foil that is fan folded into a corrugated shape offers a one piece construction with no sharp edges. The elimination of sharp endeges is an advance in the art as it facilitates better handling of the fan folded substrate during manuifacturing. In addition, the fan fold method forms a consistent diamond pattern on a the completed fan fold metal catalyst substrate face. The consistent diamond pattern possible in the embodiments of the present disclosure permit unrestricted exhaust gas flow through, and more surface area of the metal catalyst fan fold substrate is exposed to the exhaust gas stream to facilitate improved emission control. Moreover, the fan fold metal catalyst substrate of the present disclosure offers presents less potential for slippage relative to stacked and folded metal catalyst layers if the bonds used in the fan fold metal catalyst made according to the present disclosure are compromised due to its one piece construction, than if the bonds are compromised in fan fold metal catalyst substrate made using a prior stack and fold method.
A one piece construction also has manufacturing advantages. Among these is that the flow path of the foil can go directly from the spool to the corrugator to a fan fold device. There is no need for a corrugated foil spool reversal. Folded foil layers will stay in the correct sequence and orientation, and the possibility of a lost layer is eliminated. The fan fold method as set forth in disclosed embodiments addresses weld failures by using one continuous strip of foil. The foil is folded back and forth to create any desired shape having any desired configuration between the folds such as a diamond shaped herringbone configuration. The use of the continuous foil also improves shear strength of the finished product over fan folded metal catalyst substrates made accordining to the cut and stack method.
Turning now to the drawings wherein like numbers refer to like structures, and particualry to
The improved regularity of the diamond pattern is apparent when comparing the pattern formed in
Turning now to
The dies have angled die surfaces 44, 46, 48 and 50, respectively, to form the fan folds when the tool is operated. Each opposed die has a recess 52, 54, repectively within which is disposed fan fold tool inserts 56 and 58 respectively, reciprocally moveable within said recesses. The fan folding tool dies are made of a hard material such steel, and tool inserts may be made of composite hardened powdered metals such a tungsten carbide or other hardened metal inserts so that the inserts have long lofe and are harder than the material that they will encounter when making the as is well known in the art. In operation, a sheet of metal foil 60 is moved bi directionally between the opposed dies. The tools 40 and 42 are positioned relative to each other so that when the dies are moved into engagement with the metal foil, the inserts are sequentially moved into engagement with the foil and force the foil to bend, thereby creating the fan folds in the metal foil. In one example, the fan fold substrate can be made by moving a sheet of metal foil substrate bi-directionally in a folding tool having dies that when moved together impart an angled fold into the substrate at a predetermined place on the substrate.
While one embodiment has been described, it is apparent to those skilled in the art that many variations and modifications are possible without departing from the scope and spirit of the concept as described. Moreover, it is understood that the terminology used in this application are words of description and not words of limitation.
This application claims the benefit of and priority to PCT Application No. PCT/US2015/055440, filed Oct. 14, 2015 and U.S. Provisional Patent Application No. 62/064,144 filed on Oct. 15, 2014, which are hereby incorporated by reference in their entireties.
Filing Document | Filing Date | Country | Kind |
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PCT/US2015/055440 | 10/14/2015 | WO | 00 |
Number | Date | Country | |
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62064144 | Oct 2014 | US |