US 7,412,866 B2
Tubular articles with varying wall thickness and method of manufacturing same
Mamad Jahani, Ontario (Canada); and Colin Newport, Ontario (Canada)
Assigned to ArcelorMittal Tubular Products Canada Inc., Hamilton, Ontario (Canada)
Filed on Oct. 28, 2005, as Appl. No. 11/261,369.
Claims priority of provisional application 60/622614, filed on Oct. 28, 2004.
Prior Publication US 2006/0131949 A1, Jun. 22, 2006
Int. Cl. B21D 17/02 (2006.01); B60B 37/00 (2006.01)
U.S. Cl. 72—370.01  [72/370.14; 72/370.15; 72/370.23; 72/260; 72/276; 72/283; 301/124.1] 9 Claims
OG exemplary drawing
 
1. A method for manufacturing a tubular article, the tubular article defining a longitudinal axis along its length, the tubular article having a first end, an opposite second end and a main body extending between the first and second ends,
the main body including a locally outwardly thickened first region spaced from the first end and a locally inwardly thickened second region between the first region and the second end, the second region being spaced from the second end,
the first region having a first wall thickness, a first inner diameter and a first outer diameter, and the second region having a second wall thickness, a second inner diameter and a second outer diameter,
the method comprising the steps of:
a) providing a tubular blank, the tubular blank having an inner surface and an outer surface;
b) axially inserting a mandrel into the tubular blank, the mandrel having a first mandrel end, a second mandrel end and a mandrel main body extending between the first and second mandrel ends,
the mandrel main body having a first section corresponding to the first region of the main body of the tubular article, the first section having a locally reduced first diameter corresponding to the first wall thickness,
and a second section corresponding to the second region of the main body of the tubular article, the second section having a locally reduced second diameter corresponding to the second wall thickness,
the first and second mandrel ends and the mandrel main body defining a longitudinal cross sectional mandrel profile,
c) longitudinally forcing the tubular blank with the mandrel contained therein through a throat of a first die to deform the inner surface of the tubular blank to conform to the mandrel profile and to obtain a deformed tubular blank having a first thickened region and a second thickened region corresponding to the first and second sections of the mandrel, respectively;
d) separating the mandrel from the deformed tubular blank while preventing the deformed tubular blank from passing through the throat, to cause outward deformation of the outer surface of the deformed tubular blank in the first and second thickened regions; and
e) forcing inwardly the second thickened region of the deformed and separated tubular blank to form the second region of the tubular article.