Abstract: The invention involves the use of laser beam welding for the mass production of welded shells for sheet metal cans. The high requirements as to the precision of the welded seam are obtained through a guide system for exactly guiding pieces to the welding machine and consisting of an X-rail, a guide bar and the spring loaded jaws of a caterpillar tractor. A smooth welded seam is produced on the inner side of the can shell by having the seam welded from the inside of the can shell as well as from the outside by means of a laser beam.

Abstract: A method and apparatus are provided for controlled grinding of roller surfaces. A rotary drive rotates a roller and a grinding wheel is rotated, which has a rotation axis parallel to the axis of the roller. The rotating grinding wheel is pressed against the rotating roller at a certain position along the axis of the roller. The grinding wheel is moved along the direction of its axis. Simultaneously, the surface of the roller is tested with an eddy current test probe disposed substantially at a corresponding position along the axis of the roller as the grinding wheel, however, the eddy current test probe is staggered with respect to the grinding wheel by a suitable angle around the roller axis. The signals from the eddy current test probe are processed by an analog-digital converter and then by a digital processor.