Method and apparatus of producing a welded connection between the surfaces of two planar workpieces

Method for producing a linear welded connection between a first workpiece (10) and a second workpiece (11), comprising the following steps of:

• providing a first workpiece (10) and a second workpiece (11),
• arranging the second workpiece (11) on a surface of the first workpiece (10), and
• placing a friction tool (1) by the friction area (4) thereof onto that surface of the second workpiece (11) which is remote from the first workpiece (10),
• rotating the friction tool (1), with the result that a welded connection is formed between the first workpiece (10) and the second workpiece (11), the friction area (4) rubbing on that surface of the second workpiece (11) which is remote from the first workpiece (10), the friction tool (1) being moved during the rotation thereof along that surface of the second workpiece (11) which is remote from the first workpiece (10) and the friction tool (1) being rotated about an axis (3) perpendicular to that surface of the second workpiece (11) which is remote from the first workpiece (10), the contact region between the friction area (4) and the second workpiece (11) running completely in that surface of the second workpiece (11) which is remote from the first workpiece (10), so that the friction tool does not penetrate into the volume of the second workpiece (11), and the rotation of the friction tool (1) effecting a material transport from the edge of the friction tool (1) towards the axis (3) of rotation by means of grooves (22, 22′) running in the plane of the friction area (4), the grooves (22, 22′) proceeding from the outer edge region of the friction area (4) and the grooves (22, 22′) running with an inclination with respect to the tangent of the circumference of the friction area (4) towards the centre (Z).