Abstract: An apparatus is provided for producing metallic heat exchanger tubes having a heat exchange surface that is increased by fins. A rotating tube has helically wound on its outer surface a strip that forms the fins, with this strip being fed to the tube surface under tension, and with the bottom edge of the strip being welded to the tube. The contact surface that exists between the tube and the bottom edge of the strip, and that extends helically on the surface of the tube, is fused exclusively at the surface of the tube with a laser beam that is directed in the region where the strip runs onto the surface of the tube, and that fuses a portion of the tube surface that in the axial direction of the tube corresponds at least to the width of the bottom edge of the strip and in the circumferential direction corresponds approximately to the same amount. At the same time, the laser beam fuses the bottom edge of the incoming strip in the region where the strip runs onto the surface of the tube.

Abstract: A method and apparatus for producing metallic heat exchanger tubes having a heat exchange surface that is increased by fins. A rotating tube has helically wound on its outer surface a strip that forms the fins, with this strip being fed to the tube surface under tension, and with the bottom edge of the strip being welded to the tube. The contact surface that exists between the tube and the bottom edge of the strip, and that extends helically on the surface of the tube, is fused exclusively at the surface of the tube with a laser beam that is directed in the region where the strip runs onto the surface of the tube, and that fuses a portion of the tube surface that in the axial direction of the tube corresponds at least to the width of the bottom edge of the strip and in the circumferential direction corresponds approximately to the same amount. At the same time, the laser beam fuses the bottom edge of the incoming strip in the region where the strip runs onto the surface of the tube.