Metal deforming – By pulling workpiece through closed periphery die – With cutting
Patent
1996-09-25
1998-09-22
Crane, Daniel C.
Metal deforming
By pulling workpiece through closed periphery die
With cutting
72283, 83885, B21C 124
Patent
active
058098224
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/CH95/00016, filed Jan. 25, 1995.
The invention relates to a method for producing a metallic hollow body having a cylindrical shell which is provided on its outer surface with at least one predetermined breaking line.
Cylindrical hollow bodies of this type can in particular be hollow bodies with a thin wall which are, for example, adapted for use as metallic packing bodies as also as so-called splittable cannula which are used to introduce medical devices, such as catheters, endoscopes, etc., into the human or animal body. The provided predetermined breaking lines make it possible to remove the packing of the cannula without damaging the items contained therein, for example, sensible foodstuffs, precision apparatus, articles of art, jewelry, biologic preparations, such as virus and bacteries, electronic circuits, in particular memory units to be protected from light and electromagnetic radiation, or the mentioned medical instruments. In the case of a splittable cannula, the predetermined breaking line has to render possible the removal of the cannula after the introduction of the instruments concerned without wounding the human or animal body. With such a hollow body, it is in particular possible to provide a container for gas-, vacuum- and radiation-safe preservation, the opening of which must be effected without touching the item to be protected, thus in particular in a sterile way.
SUMMARY OF THE INVENTION
It is an object of the invention to produce said predetermined breaking line on the outer wall of a metallic hollow body, in particular of a hollow body with thin wall, in a continuous manufacturing process, whereby in particular a breaking line should be achieved and the desired outer and inner shape of the hollow body should be maintained.
If the predetermined breaking lines of such a hollow body are made, for example, by milling or stamping, either sharp edges or burrs occur which are an additional source of wounding and infection, in particular in medical use, or a deformation of the wall of the hollow body occurs which causes a modification of the shape of its cross-section in the region of the predetermined breaking line. In a stamping process, furthermore a deformation of the cross section of the hollow body as a whole is produced which can lead to high frictional forces, for example in the case of a splittable cannula having a rotational symmetry, when a medical instrument with narrow dimensional tolerances with respect to the inner diameter of the cannula is being introduced, and thus the medical action is hindered. On the other hand, such narrow dimensional tolerances are required to achieve tightness between the cannula and the medical instrument.
The method according to the invention is characterized in that the shell is formed by a drawing process and the predetermined breaking line is produced continuously by non-chip forming on the outer surface of said shell before, after or during this drawing process.
The predetermined breaking line can in particular be produced by rolling-in. A final calibration of the hollow body can be effected by a drawing process subsequent to the production by rolling-in of the predetermined breaking line.
The invention further relates to a hollow body produced according to such a method which has a constant wall thickness in the vicinity of the predetermined breaking line. Preferably, the outer surface of the shell of such a hollow body is practically closed in the vicinity of the predetermined breaking line.
The predetermined breaking line can run spirally around the shell of such a hollow body. Furthermore, the hollow body can comprise two predetermined breaking lines shifted, with respect to each other, for example by 180.degree.. Such a hollow body can have a small wall thickness as compared to its cross-sectional dimensions and its general outer and inner shape does not exhibit a deviation from a desired shape.
A device according to the invention for carrying out the present method is characterized in that it comprises m
REFERENCES:
patent: 3487673 (1970-01-01), House
patent: 3494164 (1970-02-01), Rehm
patent: 3744290 (1973-07-01), Sirois
patent: 4057992 (1977-11-01), Willimzik
patent: 4313328 (1982-02-01), Janssen
patent: 4377165 (1983-03-01), Luther et al.
patent: 4403491 (1983-09-01), Wassen
patent: 4449973 (1984-05-01), Luther
patent: 4776846 (1988-10-01), Wells
Browning Clifford W.
Crane Daniel C.
LandOfFree
Method of producing a metallic hollow body with a breaking line does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing a metallic hollow body with a breaking line, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing a metallic hollow body with a breaking line will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1612981