Method and device for welding workpieces

1 . Method of welding workpieces ( 3 , 5 ), particularly coated workpieces, by which, by means of a device ( 1 ), at least at the welding point, alternately a zero gap and an outgassing gap (S A ) adjustable in its height for the escape of the gases and vapors occurring during the welding operation are generated, for this purpose at least a first workpiece ( 3 ) being moved relative to a second workpiece ( 5 ), characterized in that the relative movement between the workpieces ( 3 , 5 ) is force-controlled and/or path-controlled.

2 . Method according to claim 1 ,

characterized in that, for generating an outgassing gap (S A ) between the workpieces ( 3 , 5 ) to be welded, of which preferably at least one is a sheet metal part, the workpieces ( 3 , 5 ) are placed upon one another at the welding point in a force-free manner, the height of the gap (S 0 ) being—preferably exclusively—determined by material-caused and/or manufacturing-caused inaccuracies of the workpieces ( 3 , 5 ).

3 . Method according to claim 1 or 2 ,

characterized in that the outgassing gap (S A ) has a height which is in the range of from 0.1 mm to 1 mm and preferably amounts to approximately 0.1 mm to 0.3 mm.

4 . Method according to one of claims 1 to 3 ,

characterized in that, for generating the technical zero gap between the workpieces ( 3 , 5 ) at the welding point at least one of the workpieces ( 3 ) is pressed by means of at least a first contact pressure element ( 9 ; 9 A) with a defined adjustable contact pressure force (F_target) against the other workpiece ( 5 ).

5 . Method according to claim 4 ,

characterized in that the first contact pressure element ( 9 ) is displaced back by a defined adjustable path (path Δz) after the technical zero gap was generated between the workpieces ( 3 , 5 ) and maintained for a definable time period, and in that, in the process,the outgassing gap (S A ) between the workpieces ( 3 , 5 ) is generated—preferably exclusively on the basis of the material-caused restoring forces of the at least one workpiece ( 3 ) interacting with the contact pressure element ( 9 ).

6 . Method according to claim 4 ,

characterized in that, after the technical zero gap has been generated between the workpieces ( 3 , 5 ) and was maintained for a definable time period, the contact pressure force (F_target) is reduced to a definable value, so that the outgassing gap (S A ) is generated between the workpieces ( 3 , 5 )—preferably exclusively on the basis of the material-caused restoring forces of the at least one workpiece ( 3 ) interacting with the contact pressure element ( 9 ).

7 . Method according to claim 5 or 6 ,

characterized in that, after a definable time period, a technical zero gap is formed again between the workpieces ( 3 , 5 ) in that the first contact pressure element ( 9 ; 9 A) presses the one workpiece ( 3 ) with a defined adjustable contact pressure force (F_target) against the other workpiece ( 5 ).

8 . Method according to one of claims 1 to 4 ,

characterized in that, after the technical zero gap was generated between the workpieces ( 3 , 5 ) and was maintained for a definable time period, the first contact pressure element ( 9 A) is displaced back so far that a second contact pressure element ( 9 B)—viewed in the direction of the contact pressure force (F_target)—is arranged in front of the first contact pressure element ( 9 A) and at a definable distance with respect to the zero gap, onto which the workpiece ( 3 ) places itself or is placed which previously was interacting with the first contact pressure element ( 9 a ), while forming the outgassing gap (S A ).

9 . Method according to claim 8 ,

characterized in that after a definable time period, a technical zero gap is formed again between the workpieces ( 3 , 5 ) in that the first contact pressure element ( 9 A)—viewed in the direction of the contact pressure force (F_target)—is moved by a distance (Δz) corresponding to the height of the desired outgassing gap (S A ) in front of the second contact pressure element ( 9 B), and then both contact pressure elements ( 9 A, 9 B), while maintaining their distance (Δz) from one another, are moved so far in the direction of the workpieces ( 3 , 5 ) that the first contact pressure element ( 9 A) presses the one workpiece ( 3 ) with a defined adjustable contact pressure force (F target) against the other workpiece ( 5 ).

10 . Method according to one of claims 1 to 9 ,

characterized in that a zero gap and an outgassing gap (S A ) between the workpieces ( 3 , 5 ) are formed at least once during the welding process.

11 . Method according to one of claims 1 to 10 ,

characterized in that the workpieces ( 3 , 5 ) to be welded are welded to one another by means of a high-energy, preferably continuous irradiation.

12 . Device for implementing the method according to one of claims 1 to 11 , having at least one oscillatingly displaceable contact pressure element ( 9 ; 9 A, 9 b ) interacting with at least one of the workpieces ( 3 , 5 ) to be welded together, for generating a zero gap between the workpieces ( 3 , 5 ),

characterized by a control unit for the force-controlled and/or path-controlled adjustment of the oscillation movement of the contact pressure element ( 9 ; 9 A, 9 B) during the welding process.

13 . Device according to claim 12 ,

characterized in that the control unit has at least one sensor for determining the contact pressure force of the contract pressure element ( 9 ) onto the workpiece ( 3 ) and/or the displacement path of the contact pressure element ( 9 ).

14 . Device according to claim 12 or 13 ,

characterized by at least two mechanically mutually coupled contact pressure elements ( 9 A, 9 B).

15 . Device according to one of claims 12 to 14 ,

characterized in that the contact pressure element ( 9 ; 9 A, 9 B) can be force-lockingly or form-lockingly coupled with at least one of the workpieces.