Abstract: The invention relates to a friction stir welding apparatus for joining workpieces 1, 2, having a welding pin 3, which is rotatable about its center axis 9 by means of a drive, and having at least one clamping apparatus for clamping the workpieces 1, 2 to be joined, characterized in that the clamping apparatus comprises at least two clamping elements 10, 11, which respectively have an undercut guideway 12, the guideways 12 being arranged parallel to one another and parallel to a joining region 8, in that between the clamping elements 10, 11 is arranged a sliding element 13, which is secured by the guideways 12 against the workpieces 1, 2 and is translatorily displaceable along the guideways 12, and in that the sliding element 12 is provided with an opening 14 for the lead-through of the welding pin 3, and further relates to a method for friction stir welding, using the above-stated apparatus.

Abstract: The invention relates to a friction stir welding apparatus for joining workpieces 1, 2, having a welding pin 3, which is rotatable about its center axis 9 by means of a drive, and having at least one clamping apparatus for clamping the workpieces 1, 2 to be joined, characterized in that the clamping apparatus comprises at least two clamping elements 10, 11, which respectively have an undercut guideway 12, the guideways 12 being arranged parallel to one another and parallel to a joining region 8, in that between the clamping elements 10, 11 is arranged a sliding element 13, which is secured by the guideways 12 against the workpieces 1, 2 and is translatorily displaceable along the guideways 12, and in that the sliding element 12 is provided with an opening 14 for the lead-through of the welding pin 3, and further relates to a method for friction stir welding, using the above-stated apparatus.