Method for making catalytic converters with automated substrate crack detection
A method for making catalytic converters with automated crack detection includes forming a rigid housing, providing a substrate shaped for reception in the housing, and forming a mat shaped to cover the exterior surface of the substrate and having a thickness which creates a tight friction fit between the substrate and the housing when the same are assembled. The mat is wrapped around the substrate, and the wrapped substrate is then stuffed into the housing using a reciprocating ram or the like that extends at a relatively constant speed. The stuffing force and the ram position are measured and recorded regularly to define an array of data. The data is analyzed for any abrupt changes in the stuffing force as a function of the ram position indicating a crack in the assembled substrate.
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The present invention relates to catalytic converters for internal combustion engine exhaust gases and the like, and in particular to a method for making catalytic converters with automated crack detection.
Catalytic converters are commonly used to reduce noxious emissions in the exhaust gases of internal combustion engines, particularly those associated with vehicles. Such catalytic converters typically include a substrate made from cordierite, silicon carbide, aluminum titanate or the like, and have a honeycomb construction with axially extending, open ended cells through which the exhaust gases pass for treatment. Such substrates, which are relatively fragile or frangible, are wrapped with a mat and then stuffed into a rigid housing to create a tight friction fit between the substrate and the housing. Due to the fragile nature of the substrates, the same often develop cracks or fissures therein either during handling, prior to stuffing in the housing, or during the stuffing process itself. Such cracks can severely impair the operation and effectiveness of the catalytic converter, and therefore must be detected and addressed prior to use of the catalytic converter in a vehicle.
While visual inspection of the finished catalytic converter parts does detect some such substrate cracks, such processes are relatively time-consuming, labor intensive, and are not very effective in locating internal fissures in the substrate.
Hence, a process for making catalytic converter having an automated crack detection system which is reliable, efficient and effective would clearly be beneficial.
SUMMARY OF THE INVENTIONOne aspect of the present invention is to provide a method for making catalytic converters with automated substrate crack detection, comprising the steps of forming a rigid housing into a predetermined size and shape with a hollow interior, and providing a catalytic converter substrate having an exterior surface and a predetermined size and shape similar to the size and shape of the housing to define a gap with a predetermined width between the substrate and the housing when the same are assembled. The method also includes the steps of forming a mat having a size and shape configured to cover the exterior surface of the substrate, and a predetermined thickness which is greater than the width of the gap to create a tight friction fit between the housing and the substrate when the same are assembled, and wrapping the mat around the outer surface of the substrate to define a wrapped substrate. The method further includes the steps of stuffing the wrapped substrate into the interior of the housing using a reciprocating ram or the like which extends at a predetermined, relatively constant speed, and regularly measuring the force applied by the ram to the wrapped substrate during the stuffing step. The method further comprises the steps of regularly recording the force and the associated position of the ram during the stuffing step, comparing the force as a function of the position of the ram to define an array of data, and analyzing the array of data for any abrupt changes in the force as a function of the position of the ram indicating a crack in the assembled substrate.
Another aspect of the present invention is a method for making catalytic converters with automated substrate crack detection, comprising the steps of forming a rigid housing into a predetermined size and shape with a hollow interior, and providing a catalytic converter substrate having an exterior surface and a predetermined size and shape similar to the size and shape of the housing to define a gap with a predetermined width between the substrate and the housing when the same are assembled. The method also includes the steps of forming a mat having a size and shape configured to cover the exterior surface of the substrate, and a predetermined thickness which is greater than the width of the gap to create a tight friction fit between the housing and the substrate when the same are assembled, and wrapping the mat around the outer surface of the substrate to define a wrapped substrate. The method further includes the steps of inserting the wrapped substrate into the interior of the housing at a predetermined, relatively constant speed, and regularly measuring the force applied to the wrapped substrate during the inserting step. The method further includes the steps of regularly recording the force and the associated position of the wrapped substrate during the inserting step, comparing the force as a function of the position of the wrapped substrate to define an array of data, and analyzing the array of data for any abrupt changes in the force as a function of the position of the wrapped substrate indicating a crack in the assembled substrate.
Yet another aspect of the present invention is a method for making catalytic converters with automated substrate crack detection, comprising the steps of forming a housing into a predetermined size and shape with a hollow interior, and providing a catalytic converter substrate having a predetermined size and shape similar to the size and shape of the housing, with a marginal sidewall surface, opposite end wall surfaces and a honeycomb construction defined by a plurality of axially extending cells having a common shape and open ends. The method also includes the steps of forming an insulative mat having a size and shape configured to cover the marginal sidewall surface of the substrate, and wrapping the mat around the marginal sidewall surface of the substrate to define a wrapped substrate. The method also includes the steps of inserting the wrapped substrate into the interior of the housing, recording a digital image of at least one of the end wall surfaces of the substrate, and processing the image with computer-aided image processing to identify irregularities in the shape of the cells indicating a crack in the substrate.
The method for making catalytic converters with automated substrate crack detection is reliable, efficient, effective and particularly well adapted for the proposed use. These and other advantages of the invention will be further understood and appreciated by those skilled in the art by reference to the following written specification, claims and appended drawings.
For purposes of description herein, the terms “upper”, “lower”, “right”, “left”, “rear”, “front”, “vertical”, “horizontal” and derivative thereof shall relate to the invention as oriented in
The reference numeral 1 (
The illustrated substrate 4 has a generally cylindrical shape, including flat, circular top and bottom surfaces 12 and 13, which are arranged in a generally mutually parallel relationship. Substrate 4 is constructed from a suitable catalytic converter material, such as cordierite, silicon carbide, aluminum titanate or the like, and has a honeycomb construction defined by a plurality of axially extending cells 14 having a common shape and open ends 15. In the example illustrated in
The illustrated housing 2 has a generally cylindrical shape similar to the size and shape of substrate 4 to receive the same within the interior 3 thereof. The illustrated housing 2 includes a cylindrical sidewall 18 which defines a circular end edge 19 at one end thereof and a reduced neck portion 20 at the opposite end thereof. Housing 2 has a rigid construction, and is typically constructed from a metal, such as steel or the like, which is capable of withstanding the substantial heat and high temperatures associated with engine exhaust gases.
The illustrated mat 6 is insulative in nature, and as best shown by the broken lines in
The assembly machine 35 illustrated in
In the insertion position illustrated in
For example, in the graph illustrated in
As shown in
As will be apparent to those skilled in the art, the load/deflection analysis crack detection technique, and the digital imaging crack technique, as described above, can be used either separately, or together. When used together, additional accuracy and reliability are realized, particularly when the digital imaging technique is performed after the load/deflection analysis technique.
In the foregoing description, it will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed herein. Such modifications are to be considered as included in the following claims, unless these claims by their language expressly state otherwise.
Claims
1. A method for making catalytic converters with automated substrate crack detection, comprising:
- forming a rigid housing into a predetermined size and shape with a hollow interior;
- providing a catalytic converter substrate having an exterior surface and a predetermined size and shape similar to the size and shape of the housing to define a gap of predetermined width between the substrate and the housing when the same are assembled;
- forming a mat having a size and shape configured to cover the exterior surface of the substrate, and a predetermined thickness which is greater than the width of the gap to create a tight friction fit between the housing and the substrate when the same are assembled;
- wrapping the mat around the outer surface of the substrate to define a wrapped substrate;
- stuffing the wrapped substrate into the interior of the housing using a reciprocating ram which extends at a predetermined, relatively constant speed;
- regularly measuring the force applied by the ram to the wrapped substrate during said stuffing step;
- regularly recording the force and the associated position of the ram during said stuffing step;
- comparing the force as a function of the position of the ram to define an array of data; and
- analyzing the array of data for any abrupt change in the force as a function of the position of the ram indicating a crack in the assembled substrate.
2. A method as set forth in claim 1, including:
- automatically unstuffing the wrapped substrate from the housing upon detection of a crack in the substrate during said data analyzing step.
3. A method as set forth in claim 2, wherein:
- said substrate providing step includes providing the substrate with a marginal sidewall surface, opposite end wall surfaces, and a honeycomb construction defined by a plurality of axially extending cells with a common shape and open ends; and including
- recording a digital image of at least one of the end wall surfaces of the substrate; and
- processing the image with computer-aided image processing to identify irregularities in the shape of the cells indicating a crack in the substrate.
4. A method as set forth in claim 3, wherein:
- said force comparing step includes displaying a graph of the force as a function of the position of the ram.
5. A method as set forth in claim 4, wherein:
- said data analyzing step includes processing the array of data with a programmable logic controller.
6. A method as set forth in claim 5, wherein:
- said graph displaying step includes creating a generally curvilinear graph; and
- said data analyzing step includes identifying abrupt changes in the slope of the curvilinear graph.
7. A method as set forth in claim 6, wherein:
- said image processing step includes processing the image with computer-aided blob tool software.
8. A method as set forth in claim 7, wherein:
- said image processing step identifies areas of the one end wall surface of the substrate having a non-uniform density of the cells.
9. A method as set forth in claim 8, wherein:
- said image recording step and said image processing step are performed after said substrate stuffing step.
10. A method as set forth in claim 9, wherein:
- said image recording step and said image processing step are performed after said data analyzing step.
11. A method as set forth in claim 10, wherein:
- said substrate providing step includes forming the substrate from cordierite, silicon carbide or aluminum titanate.
12. A method as set forth in claim 1, wherein:
- said substrate providing step includes providing the substrate with a marginal sidewall surface, opposite end wall surfaces, and a honeycomb construction defined by a plurality of axially extending cells with a common shape and open ends; and including
- recording a digital image of at least one of the end wall surfaces of the substrate; and
- processing the image with computer-aided image processing to identify irregularities in the shape of the cells indicating a crack in the substrate.
13. A method as set forth in claim 1, wherein:
- said data analyzing step includes processing the array of data with a programmable logic controller.
14. A method as set forth in claim 1, wherein:
- said substrate providing step includes forming the substrate from cordierite, silicon carbide or aluminum titanate.
15. A method for making catalytic converters with automated substrate crack detection, comprising:
- forming a rigid housing into a predetermined size and shape with a hollow interior;
- providing a catalytic converter substrate having an exterior surface and a predetermined size and shape similar to the size and shape of the housing to define a gap of predetermined width between the substrate and the housing when the same are assembled;
- forming a mat having a size and shape configured to cover the exterior surface of the substrate, and a predetermined thickness which is greater than the width of the gap to create a tight friction fit between the housing and the substrate when the same are assembled;
- wrapping the mat around the outer surface of the substrate to define a wrapped substrate;
- inserting the wrapped substrate into the interior of the housing at a predetermined, relatively constant speed;
- regularly measuring the force applied to the wrapped substrate during said inserting step;
- regularly recording the force and the associated position of the wrapped substrate during said inserting step;
- comparing the force as a function of the position of the wrapped substrate to define an array of data; and
- analyzing the array of data for any abrupt change in the force as a function of the position of the wrapped substrate indicating a crack in the assembled substrate.
16. A method as set forth in claim 15, including:
- automatically unstuffing the wrapped substrate from the housing upon detection of a crack in the substrate during said data analyzing step.
17. A method as set forth in claim 15, wherein:
- said substrate providing step includes providing the substrate with a marginal sidewall surface, opposite end wall surfaces, and a honeycomb construction defined by a plurality of axially extending cells with a common shape and open ends; and including
- recording a digital image of at least one of the end wall surfaces of the substrate; and
- processing the image with computer-aided image processing to identify irregularities in the shape of the cells indicating a crack in the substrate.
18. A method for making catalytic converters with automated substrate crack detection, comprising:
- forming a housing into a predetermined size and shape with a hollow interior;
- providing a catalytic converter substrate having a predetermined size and shape similar to the size and shape of the housing, with a marginal sidewall surface, opposite end wall surfaces and a honeycomb construction defined by a plurality of axially extending cells having a common shape and open ends;
- forming an insulative mat having a size and shape configured to cover the marginal sidewall surface of the substrate;
- wrapping the mat around the marginal sidewall surface of the substrate to define a wrapped substrate;
- inserting the wrapped substrate into the interior of the housing;
- recording a digital image of at least one of the end wall surfaces of the substrate; and
- processing the image with computer-aided image processing to identify irregularities in the shape of the cells indicating a crack in the substrate.
19. A method as set forth in claim 18, wherein:
- said image processing step includes processing the image with computer-aided blob tool software.
20. A method as set forth in claim 19, wherein:
- said image processing step identifies areas of the one end wall surface of the substrate having a non-uniform density of the cells.
Type: Application
Filed: Sep 12, 2006
Publication Date: Mar 20, 2008
Applicant:
Inventor: Frederick B. Hill (Clarkston, MI)
Application Number: 11/520,017
International Classification: B21D 51/16 (20060101);