Method for production of a steel tubular product, in particular an airbag tubular product, and a steel tubular product produced using this method, in particular an airbag tubular product

A method for production of an airbag tube, the method comprising:

• a step a) of providing a steel tube having an axial length, an outer diameter which is perpendicular to the axial length, and an inner diameter which is parallel to the outer diameter, wherein the axial length is greater than each of the outer diameter and the inner diameter;
• a step b) of shaping an end region the steel tube into a pre-geometry, the shaping being performed by axially moving the steel tube into an outer tool so as to thereby provide the pre-geometry with the outer diameter which is reduced in the end region in the outer tool and so that an end part of a length of the end region is parallel to a rest of the steel tube which was not shaped, wherein the shaping in step b) is performed via a cold forming together with a lubricant or via a cold drawing together with a lubricant;
• a step c) of calibrating an inner diameter of the pre-geometry, the calibrating being performed while the pre-geometry is arranged within the outer tool by,
• introducing an inner mandrel having an outer diameter which corresponds to the inner diameter of the pre-geometry into the end region of the pre-geometry, and
• pressing the pre-geometry against the outer tool so that the inner diameter of the pre-geometry is calibrated via a shaping in the end region,
• wherein the shaping in step c) is performed via a cold forming together with a lubricant or via a cold drawing together with a lubricant, without a preheating and without heated tools;
• a step d) of removing the pre-geometry from the outer tool and removing the inner mandrel from the pre-geometry;
• a step e) of axially moving the pre-geometry into a drawing tool comprising a roll-in contour which comprises a concave shape, thereby simultaneously shaping the pre-geometry into the airbag tube comprising a rotationally symmetrical outlet opening which is positioned centrally in an end face, wherein the shaping in step e) is performed via a hot forming together with a temperature-resistant lubricant or via a semi-hot forming together with a temperature-resistant lubricant;
• and
• a step f) of removing the airbag tube from the drawing tool,
• wherein,
• in each of the step b) and the step d), no rotation of the pre-geometry with respect to the outer tool is performed, and
• the airbag tube has a tensile strength of at least 700 MPa.

A method for production of an airbag tube, the method comprising:

• a step a) of providing a steel tube having a tensile strength of at least 700 MPa, axial length, an outer diameter which is perpendicular to the axial length, and an inner diameter which is parallel to the outer diameter, wherein the axial length is greater than each of the outer diameter and the inner diameter;
• a step b) of shaping the steel tube into a pre-geometry, the shaping being performed by axially moving the steel tube into an outer tool so as to thereby provide the pre-geometry with the outer diameter which is reduced in an end region in the outer tool, wherein the shaping in step b) is performed via a cold forming together with a lubricant or via a cold drawing together with a lubricant;
• a step c) of calibrating an inner diameter of the pre-geometry, the calibrating being performed while the pre-geometry is arranged within the outer tool by,
• introducing an inner mandrel having an outer diameter which corresponds to the inner diameter of the pre-geometry into the end region of the pre-geometry, and
• pressing the pre-geometry against the outer tool so that the inner diameter of the pre-geometry is calibrated via a shaping in the end region,
• wherein the shaping in step c) is performed via a cold forming together with a lubricant or via a cold drawing together with a lubricant, without a preheating and without heated tools;
• a step d) of removing the pre-geometry from the outer tool and removing the inner mandrel from the pre-geometry;
• a step e) of axially moving the pre-geometry into a drawing tool comprising a roll-in contour which comprises a concave shape, thereby simultaneously shaping the pre-geometry into the airbag tube comprising a rotationally symmetrical outlet opening which is positioned centrally in an end face, wherein the shaping in step e) is performed via a hot forming together with a temperature-resistant lubricant or as a semi-hot forming together with a temperature-resistant lubricant;
• and
• a step f) of removing the airbag tube from the drawing tool,
• wherein,
• in each of the step b) and the step d), no rotation of the pre-geometry with respect to the outer tool is performed, and
• the airbag tube has a tensile strength of at least 700 MPa.