Abstract: An energy-beam welding machine has a vacuum chamber consisting of upper and lower parts. For receiving workpieces of various heights, the lower part of the chamber can be lowered to a position below a conveying plane in which the workpieces can be advanced and a lifting column which carries a workpiece-receiving device at its upper end is movable in the vertical direction relative to the lower part of the chamber. The extent of the relative movement can be varied by a displaceable stop between the lifting column and the lower part of the chamber so that, even when the vertical dimensions of the workpieces differ, the position of the welded seams is always in the same plane, and the lower faces of the workpieces can also always be introduced laterally into the lower part of the chamber from the conveying plane.