Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Hollow or tubular part or organ
Reexamination Certificate
2000-08-29
2002-04-30
Willse, David H. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Hollow or tubular part or organ
C606S198000, C228S225000
Reexamination Certificate
active
06379392
ABSTRACT:
BACKGROUND OF THE INVENTION
Fusion welding techniques, such as laser welding, electron beam welding, tungsten inert gas welding, plasma welding and others, commonly leave a pool of molten metal at the end of the weld pass that solidifies after heat input to the weld has terminated. The terminal pool is commonly the weakest portion of the weld and is often the site of fracture initiation under moderate to low stress. Welds produced in nickel-titanium alloys (nitinol) are particularly prone to this problem.
SUMMARY OF THE INVENTION
The invention comprises a method of moving the location of the terminal pool in fusion welds to better accommodate high stress areas. This is accomplished by utilizing a multiple pass weld technique. The welding technique utilizes weld passes which initiate at remote portions of the area to be welded such as each end of a joint to be welded, and terminate within the interior of the weld area at or near a common meeting point. The multiple passes may overlap within the weld but overlap is not required. This technique is especially useful in devices having portions comprised of nitinol which require welding, such as in medical stents.
REFERENCES:
patent: 5354623 (1994-10-01), Hall
patent: 5395390 (1995-03-01), Simon et al.
patent: 5488959 (1996-02-01), Ales
patent: 5540712 (1996-07-01), Kleshinski et al.
Boston Scientific Corporation
Phan Hieu
Vidas, Arrett&Steinkraus PA
Willse David H.
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