US 11,873,944 B2
Tubular element for gas pressure vessel, gas pressure vessel and method of manufacturing a tubular element
Daniel Lücke, Paderborn (DE); Michael Markert, Lichtenau (DE); Dirk Tegethoff, Salzkotten (DE); and Marcel Wellpott, Paderborn (DE)
Assigned to Benteler Steel/Tube GmbH
Filed by Benteler Steel/Tube GmbH, Paderborn (DE)
Filed on Sep. 20, 2019, as Appl. No. 16/577,725.
Claims priority of application No. 10 2018 123 316.7 (DE), filed on Sep. 21, 2018.
Prior Publication US 2020/0094773 A1, Mar. 26, 2020
Int. Cl. B21C 1/24 (2006.01); B21C 37/16 (2006.01); B21D 41/00 (2006.01); F16L 9/00 (2006.01); B60R 21/26 (2011.01)
CPC F16L 9/006 (2013.01) [B21C 1/24 (2013.01); B60R 21/26 (2013.01); B21C 37/16 (2013.01); B21D 41/00 (2013.01); B60R 2021/26076 (2013.01); B60R 2021/26082 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A process for producing a tubular element (1) for a gas pressure vessel of an airbag module, wherein the tubular element (1) consists of high-strength steel, has a first and a second end (17, 18) and from the first end (17) to the second end (18) the tubular element (1) has an undeformed section (11), a transition section (12) and a tapering section (13), and on the tapering section (13) at least one radially outwardly extending collar (14) is formed, wherein the collar (14) is separated from the transition section (12) by a first length section (130) having an outer diameter (A1) smaller than the outer diameter (A2) of the collar (14) and the wall thickness of the collar (14) is greater than the wall thickness of the first length section (130), characterized in that the tubular element (1) is produced according to a method comprising the following steps:
providing a tube (10) from which the tubular element (1) is to be made;
a first process step of drawing a tube end of the tube (10) to the inner diameter (I1) of the collar (14);
a second process step of forming said collar (14), which second process step is a semi-hot forming process step and is carried out by axial compression; and
a third process step of drawing the tube end to a final diameter (A3) and end forming the collar (14);
wherein in the second process step the collar (14) is pre-formed on the outside of the tapering portion (13);
wherein the second process step is carried out with a die which has a mandrel and an annular gap surrounding the mandrel, the annular gap having on the open side a shoulder in which the width of the annular gap is increased.