Method for making catalytic converters with automated substrate crack detection

Abstract

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.

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.