Claims
- 1. A method for producing helically wound lock-seam tubing from a metal strip having longitudinal edge portions, comprising the following steps:
feeding said strip to a forming head; forming said strip into a helical form in said forming head, whereby said edge portions of said helically wound strip are brought into engagement with each other; clinching said engaging edge portions of said strip to form a helically wound lock-seam on a tube formed in said forming head; feeding said helically wound lock-seam tube out of said forming head; and interlocking portions of the engaged edges that form said seam with a region of forced contact therebetween and simultaneously creating a deforming bulge in the exterior surface of said lock seam.
- 2. The method of claim 1, said interlocking step further comprising forming said deforming bulges sufficiently deeply to provide interlocking between the edge portions.
- 3. The method of claim 1, said interlocking step further comprising forming said deforming bulges transversely across said lock-seam.
- 4. The method of claim 1, said interlocking step further comprising forming said deforming bulges from side to side across said lock-seam.
- 5. The method of claim 1, said interlocking step further comprising forming said deforming bulges through all layers of the lock-seam.
- 6. The method of claim 1, said interlocking step further comprising forming at least one deforming bulge on each helical turn of said lock-seam.
- 7. The method of claim 1, further comprising spacing said deforming bulges to provide non-deformed portions along the lock-seam.
- 8. The method of claim 1, further comprising preforming said edge portions of said strip before said step of feeding into said forming head.
- 9. A helically wound lock-seam tube which is helically formed from a metal strip having longitudinal edge portions which are interlocked in a helical lock-seam, wherein the helically wound lock-seam includes edge portions forced into deforming contact with each other to lock the interlocked edge portions of the strip in the lock-seam and create deforming bulges in the lock-seam, the deforming bulges interspaced by non-deformed portions of the lock-seam.
- 10. The tube of claim 9, wherein said deforming bulges are sufficiently deep to provide interlocking between the edge portions.
- 11. The tube of claim 9, wherein the deforming bulges are formed to extend transversely across the lock-seam.
- 12. The tube of claim 9, wherein each of the deforming bulges comprises an indentation extending through all layers of the lock-seam.
- 13. The tube of claim 9, wherein at least one of said deforming bulges is provided on each helical turn of the lock-seam.
- 14. The tube of claim 9, wherein the non-expanded portions have a length along the lock-seam greater than a dimension of each of the deforming bulges along the lock-seam.
- 15. The tube of claim 9, wherein the deforming bulges are deformed on an exterior surface of the lock-seam.
- 16. The tube of claim 9, wherein the deformations are substantially equivalent to a width of the lock-seam.
- 17. An apparatus for producing helically wound lock-seam tubing from a metal strip having longitudinal edge portions comprising:
a feeder assembly operative to feed said strip; a forming head assembly operative to form said strip into helical form and to bring said edge portions of said helically formed strip into engagement with each other to form a tube; a clinching assembly for clinching said engaging edge portions of said strip to form a helically wound lock-seam on said tube formed in said forming head; and a deforming device for interlocking portions of the engaged edges that form said seam with a region of forced contact therebetween and simultaneously creating a deforming bulge in the exterior surface of said seam.
- 18. The apparatus of claim 17, wherein said deforming device further comprises a rotatable clinching roller having a periphery and a rotatable counter roller having a periphery, at least one of said rollers including a bulge formation feature on its periphery for creating said deforming bulge.
- 19. The apparatus of claim 18, wherein said at least one of said rollers is provided with a peripheral groove and a transverse ridge.
- 20. The apparatus of claim 18, wherein said at least one of said rollers comprises said clinching roller.
- 21. The apparatus of claim 18, wherein said at least one of said rollers comprises said counter roller.
- 22. The apparatus of claim 18, wherein said clinching roller is arranged outside said tube being formed, and said counter roller is arranged inside said tube being formed.
- 23. The apparatus of claim 18, wherein said clinching roller is arranged inside said tube being formed, and said counter roller is arranged outside said tube being formed.
- 24. The apparatus of claim 17, wherein said deforming device is supported on said forming head.
- 25. The apparatus of claim 17, further comprising a preforming device operative to preform said edge portions of said strip before feeding into said forming head.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of application Ser. No. 09/548,881 filed Apr. 13, 2000; which is a divisional of application Ser. No. 09/219,239 filed Dec. 22, 1998, now U.S. Pat. No. 6,085,801; which is a divisional of application Ser. No. 08/925,545 filed Sep. 8, 1997, now U.S. Pat. No. 6,003,220; which is a divisional of application Ser. No. 08/747,998 filed Nov. 12, 1996, now U.S. Pat. No. 5,720,095; which is a divisional of application Ser. No. 08/400,752 filed Mar. 8, 1995, now abandoned.
Divisions (4)
|
Number |
Date |
Country |
Parent |
09548881 |
Apr 2000 |
US |
Child |
09788858 |
Feb 2001 |
US |
Parent |
09219239 |
Dec 1998 |
US |
Child |
09548881 |
Apr 2000 |
US |
Parent |
08925545 |
Sep 1997 |
US |
Child |
09219239 |
Dec 1998 |
US |
Parent |
08747998 |
Nov 1996 |
US |
Child |
08925545 |
Sep 1997 |
US |
Continuations (1)
|
Number |
Date |
Country |
Parent |
08400752 |
Mar 1995 |
US |
Child |
08747998 |
Nov 1996 |
US |