Method for producing an individual fin-free spot scarfing cut

Claim 1

In a process for machine scarfing individual defects from the surface of a metal body, wherein a sheet-like stream of oxygen is directed obliquely against a reaction zone of molten metal to produce a thermochemical reaction thereon, and wherein relative movement is produced between the oxygen stream and the metal surface in order to continue the reaction along the length of the metal surface and to produce the desired individual scarfing cut, the improvement comprising: preventing the formation of fins along the edges of the scarfing cut by restricting the flow of said oxygen at the edges of said stream so as to gradually diminish the intensity of the oxygen stream at the edges thereof to such an extent that the flow of oxygen at the edges of the stream is insufficient to produce a scarfing reaction on the metal surface but sufficient to oxidize any molten metal at the edges of the scarfing reaction zone thereby preventing said molten metal from solidifying and adhering to the surface of said metal body along the edges of the scarfing cut in an unoxidized state and producing a fin-free scarfing cut narrower than the width of the oxygen stream, and wherein the flow of oxygen at the edges of said stream is restricted by directing said stream of scarfing oxygen through a nozzle terminating in a discharge orifice characterized by having: a. a width greater than its maximum height, and said height gradually decreasing to zero at the edges thereof, b. a center section and two end sections, the ratio of the width of the end sections of the orifice to the height of said end sections being from about 2:1 to 10:1, and c. the center section of said orifice comprising parallel upper and lower edge surfaces.