Patent ID: 7786404

Claim:
A device for the laser welding of a structure made up of elements of sheet metal, comprising: a manipulator robot with a number of axes, which includes a plurality of electric motors, which control the movement of component elements of the robot about said axes, and a programmable electronic control unit, for controlling said electric motors for the purpose of displacing a terminal component element of the robot according to any position, orientation, and path within a first predetermined three-dimensional space; said manipulator robot being provided with a device having at least one linearly mobile lens moveable in a direction parallel to a laser beam axis originating from a laser torch for adjustable focusing of a laser beam from the terminal component element to a desired target weld point on the sheet metal structure and for orienting the focused laser beam within a second predetermined three-dimensional space, the at least one linear mobile lens comprising a first and second optical groups arranged in series along the laser beam axis, for adjustably focusing the laser beam by shaping the laser beam with a predetermined diameter, the second optical group comprising a linearly mobile lens adapted for causing the beam to diverge, the device further having a fixed mirror for reflecting said laser beam of a predetermined diameter, a fixed focusing modulus of the laser beam reflected by said fixed mirror, and mirror means orientable around two axes orthogonal therebetween, for reflecting the focused laser beam according to a direction orientable in space; said control unit being programmed for displacing the aforesaid terminal component element of the robot along a simplified path in the proximity of, but not closely adjacent to, various areas of the structure to be welded, further programmable electronic control means are provided for controlling the aforesaid device for focusing and orienting the laser beam, in such a way that, whilst the terminal component element of the robot follows the aforesaid simplified path, the focused laser beam is oriented in the direction of all the various areas of the structure to be welded, and for each area it executes a laser-welding stretch or bead; wherein the further programmable electronic control means are programmed so that the laser beam spot on the structure to be welded is moved with respect thereto in the longitudinal direction of each stretch of weld at a speed which is not closely dependent from the speed of movement of said terminal component of the robot; and wherein during the movement of said manipulator robot, said terminal component element is able to adjustably focus the laser beam through linear movement of the mobile lens to keep a given area of the structure to be welded still illuminated, while the manipulator robot has already moved on.