seen for spiralformig winding of tape in the row, serskilt with oval tversektion, and device for utforande of set

摘要

A method and device for producing finned heat transfer tubing of oval cross section by winding one or more continuous metal strips around the tubing in the form of spiral fins, the contact edge of the metal strip being shaped prior to winding to present a hook-shaped ledge with an acute enclosed angle, and the neutral axis for on-edge bending being shifted to the vicinity of the contact edge by applying to the strip a tensile stress and to its upper half additional transverse compression stress, using a stretch roller and a cooperating winding guide. A lathe-like machine semi-automatically winds two metal strips onto successive lengths of oval tubing, using a carriage with two pivotable winding arms and two strip reels.