process for extracting alettature integral on flat surfaces or curves by spallation obtained by combined action of shear and bending

摘要

A method for making integral fins on plane or curved heat transfer surfaces wherein a fin is obtained by making an inclined cut on the surface itself to provide a thin strip or layer of metal connected to the surface along one edge, raising said layer and bending it around said connecting edge to a substantially perpendicular relation with respect to said surface. For putting said method into practice a finning tool is provided wherein the cutting angle of its cutting edge increases from a nose, the length of cutting edge is greater than the one of the fin to be formed and the cutting edge itself is inclined so as to obtain a cutting line inclined with respect to the profile of the surface.