Method for welding sheet metal parts
A method for butt welding of flat metal blanks in a welding machine, where two metal blanks are placed on a conveyor unit by feed devices and secured. Two edges of two metal blanks to be welded together are placed together to form a butt joint with the smallest possible gap and then welded together using a welding laser. The gap width is measured and controlled using the measured values from the welding process. The gap width is measured using a reflected-light method and the true gap width via the transmitted light method in such a way that the missing area and the missing volume in the gap can be estimated accurately.
1 . A method for butt welding of adjacent edges ( 4 , 5 ) of flat metal blanks ( 1 , 2 ) in a welding machine, comprising:
providing two flat metal blanks ( 1 , 2 ) to be welded together;
placing the two metal blanks ( 1 , 2 ) on a conveyor unit ( 37 ) and securing them in a respective position with a first edge ( 4 ) of one of the metal blanks ( 1 , 2 ) and an adjacent second edge ( 5 ) of the other of the metal blanks ( 1 , 2 ) having a smallest possible gap therebetween; and
welding the adjacent first and second edges ( 4 , 5 ) together using a welding laser ( 6 ) to form a butt joint, wherein
a gap width ( 7 ) between the first edge ( 4 ) and second edge ( 5 ) is measured and controlled via measured values from the welding process,
the gap width ( 7 ) is measured via a reflected-light method wherein light rays ( 13 , 14 , 15 , 16 ) from one or more light sources ( 11 , 12 ) are reflected between the first and second edges ( 4 , 5 ) and at least one reflected light ray ( 13 ) is captured by a camera,
a true gap width ( 9 ) equal to the minimum distance between the respective edges ( 4 , 5 ) is measured simultaneously by a transmitted light method wherein light ( 17 ) from a light source ( 18 ) is transmitted through the gap from above or below and is captured by a camera ( 20 ) from below or above, respectively, and
the gap width ( 7 ) measured via the reflected-light method and the true gap width ( 9 ) measured via the transmitted light method are used to estimate a missing area ( 8 ) or missing volume in the gap.
2 . The method according to claim 1 , wherein the reflected-light method is a laser line method.
3 . The method according to claim 2 , wherein the laser line method is a laser triangulation method.
4 . The method according to claim 2 , wherein the reflected-light method is used to measure the gap width ( 7 ) on an upper side and an opposite lower side of the metal blanks ( 1 , 2 ).
5 . The method according to claim 1 , wherein filler wire ( 10 ) is fed to the laser welding process ( 35 ).
6 . The method according to claim 5 , wherein the filler wire feed is controlled according to the estimated missing volume.
7 . The method according to claim 6 , wherein the measured gap width ( 7 ) and true gap width ( 9 ) results are analyzed using imaging techniques during the welding process in order to estimate the missing volume between the two edges ( 4 , 5 ).
8 . The method according to claim 6 , wherein one or more holes in a weld of the butt joint are detected after the welding process via a light ( 31 , 31 ) and corresponding camera ( 22 , 23 ).
9 . The method according to claim 6 , wherein the gap width ( 7 ) and the true gap width ( 9 ) are measured and analysed continuously throughout the welding process.
10 . The method according to claim 6 , wherein the transmitted light method is used to measure the true gap width ( 9 ) on an upper side and an opposite lower side of the metal blanks ( 1 , 2 ).
11 . The method according to claim 1 , wherein the measured gap width ( 7 ) and true gap width ( 9 ) results are analyzed using imaging techniques during the welding process in order to estimate the missing volume between the two edges ( 4 , 5 ).
12 . The method according to claim 11 , wherein one or more holes in a weld of the butt joint are detected after the welding process via a light ( 31 , 31 ) and corresponding camera ( 22 , 23 ).
13 . The method according to claim 11 , wherein the gap width ( 7 ) and the true gap width ( 9 ) are measured and analysed continuously throughout the welding process.
14 . The method according to claim 1 , wherein one or more holes in a weld of the butt joint are detected after the welding process via a light ( 31 , 31 ) and corresponding camera ( 22 , 23 ).
15 . The method according to claim 1 , wherein the reflected-light method uses light sources ( 11 , 12 ) for monochromatic light.
16 . The method according to claim 1 , wherein the gap width ( 7 ) and the true gap width ( 9 ) are measured and analysed continuously throughout the welding process.
17 . The method according to claim 1 , characterized in that the reflected-light method and transmitted light method utilize at least one shared camera ( 20 ).
18 . The method according to claim 1 , wherein the reflected-light method is used to measure the gap width ( 7 ) on an upper side and an opposite lower side of the metal blanks ( 1 , 2 ).
19 . The method according to claim 1 , wherein the transmitted light method is used to measure the true gap width ( 9 ) on an upper side and an opposite lower side of the metal blanks ( 1 , 2 ).
20 . The method of claim 1 , wherein the flat metal blanks are utilized to produce tailored blanks for manufacturing a car body.