Applications with Medium Laser Power
Several laser welding applications have recently evolved in this power range of 1 to 10 kW. Because, the laser provides a basis for cost effective, high volume production, strong interest has centered around applications in the automotive industry. An example of the advantages of laser welding for automotive production is provided by a description of the automatic underbody welding system developed for the Ford Motor Company. The laser remain stationary and motion of the output beam is provided in four degrees of freedom by a combination of moving mirrors. Beam translation along horizontal and vertical axes is achieved by moving a turning mirror and the focus head along horizontal and vertical tracks. Two rotational degrees of freedom for the beam are provided by a unique focusing system employing a 90 ° - off - axis, parabolic mirror. The ease with which the beam may be directed with this optical arrangement, coupled with a longitudinal degree of freedom obtained by moving the automotive under body, facilitates welding over the complex contours associated with the various humps and ridges of the underbody. With this system, penetrations of 2.5 mm have been achieved at speeds greater than 5 m /min and penetrations of 1.5 mm have been achieved at speeds near 12 m / min.
This welding performance allows up to 60 underbodies to be welded per hour on an assembly line basis. A lap weld is formed, which provides a strong, continuous joint and further seals the joint area such that a secondary sealing process (required for spot welding) is eliminated. The flexibility of the computer controlled system allows welding parameters for a number of different underbody designs to be stored, in the central computer memory and selected as required. The underbody welding offers striking proof of the ability of the laser to produce high speed weld in large, complex parts.