Stretched metal article having reinforced terminal edge and method of making same

1. A method of forming a stretched metal workpiece having a reinforced terminal wall comprising the steps:

providing a die body defining a first longitudinal axis, and a complementary cylindrical drawing punch defining a second longitudinal axis;

orienting a planar metal blank orthogonal to said first longitudinal axis;

constructing a first annular wall transitioning immediately to a closed end orthogonal to said first longitudinal axis by stretching said planar metal blank against said die body along said first longitudinal axis;

forming an intermediate opening in said closed end circumscribed by a second annular wall extending radially away from said first annular wall by removing a portion of said closed end; and

folding said second annular wall against said first annular wall to form said reinforced terminal wall by moving said complementary cylindrical drawing punch against said second annular wall along said second longitudinal axis collinear with said first longitudinal axis.

2. The method of claim 1 wherein said closed end includes an exterior surface and an opposed interior surface, and the removing of said portion of said closed end includes punching said intermediate opening with a hole-forming punch against one of said exterior and interior surfaces and an anvil against the other of said exterior and interior surfaces.

3. The method of claim 2 wherein the folding step includes providing said complementary cylindrical drawing punch with a diameter substantially similar to a predetermined final reinforced terminal wall diameter and moving said complementary cylindrical drawing punch against said second annular wall.

4. The method of claim 3 wherein the folding step includes collinearly aligning said first longitudinal axis and said second longitudinal axis, and moving said complementary cylindrical drawing punch toward said die body.

5. The method of claim 4 wherein the folding step includes flaring said second annular wall to a diameter larger than said intermediate opening and folding said second annular wall against an exterior of said first annular wall.

6. The method of claim 4 wherein said metal blank is a web.

7. The method of claim 6 wherein all steps occur simultaneously in different portions of said web by a single motion of a press, and said web is advanced by an indexed amount for each successive motion of said press.

8. The method of claim 4 wherein the folding step includes providing said complementary cylindrical drawing punch with a diameter substantially similar to a predetermined final reinforced terminal wall diameter and moving said complementary cylindrical drawing punch against said second annular wall.

9. The method of claim 2 wherein the folding step includes flaring said second annular wall to a diameter larger than said intermediate opening and folding said second annular wall against an exterior of said first annular wall.

10. The method of claim 9 wherein said metal blank is a web.

11. The method of claim 10 wherein all steps occur simultaneously in different portions of said web by a single motion of a press, and said web is advanced by an indexed amount for each successive motion of said press.

12. The method of claim 1 wherein said stretched metal workpiece is one of a catalytic converter, a muffler head, and a dog bone.

13. A method of forming a stretched metal workpiece having a reinforced terminal wall comprising the steps:

providing a die body and a complementary punch, said die body having a single configuration and defining a first longitudinal axis;

positioning an unstretched planar metal blank against said die body orthogonal to said first longitudinal axis;

forming a first annular wall having an exterior surface and transitioning immediately to a closed end orthogonal to said first longitudinal axis by stretching said unstretched planar metal blank against said die body along said first longitudinal axis;

while maintaining said stretched metal blank against said die body,

forming an opening in said closed end, said opening circumscribed by a second annular wall extending radially away from said first annular wall; and

folding said second annular wall along said first annular wall to form said reinforced terminal wall by moving said complementary punch orthogonally against said second annular wall.