The Esab Group Inc.

Esab Welding Products, Inc.

John G Dawson, Jr

Frank J Gusky

Michael S Showalter

A block assembly for a thermochemical scarfing apparatus which allows a greater diagonal standoff distance from the metal workpiece during preheating. The block assembly comprises a base member and an extension releasably joined to the base member, and the base member and extension include an internal network of gas distribution lines for separately delivering both oxygen and fuel gas to each of a plurality of discharge openings which are disposed in a longitudinal row along the front face of the extension. A nozzle insert is releasably mounted in each discharge opening, such that during preheating, the oxygen may be discharged from each discharge opening as a central high velocity stream and the fuel gas may be discharged as a concentric stream which coaxially surrounds the central stream, and so that the momentum of the central stream is maintained. The effective flame heating distance thereby may be extended during preheating, and the block assembly may be moved back from the workpiece a significant standoff distance so as to avoid damage from dislodged molten metal slag.

Block assembly for use in metal scarfing apparatus

Nozzle insert for use in metal scarfing apparatus

A thermochemical scarfing apparatus is disclosed which allows a greater diagonal standoff distance from the metal workpiece during preheating. The operating steps of the apparatus includes preheating the end of the metal workpiece, and then scarfing the workpiece by directing a scarfing oxygen stream onto the workpiece at an acute angle and while moving the workpiece past the oxygen outlet port. The preheating step includes generating a high speed stream of oxidizing gas and a concentric stream of fuel gas coaxially about the central stream, so that the momentum of the central stream is maintained. As a result, the effective flame heating distance may be extended, and the manifold and head assembly which supports the preheating gas nozzles may be moved back from the workpiece a significant standoff distance so as to avoid damage from dislodged molten metal slag.

A thermochemical scarfing method is disclosed which allows a greater diagonal standoff distance from the metal workpiece during preheating. The method includes preheating the end of the metal workpiece, and then scarfing the workpiece by directing a scarfing oxygen stream onto the workpiece at an acute angle and while moving the workpiece past the oxygen outlet port. The preheating step includes generating a high speed stream of oxidizing gas and a concentric stream of fuel gas coaxially about the central stream, so that the momentum of the central stream is maintained. As a result, the effective flame heating distance may be extended, and the manifold and head assembly which supports the preheating gas nozzles may be moved back from the workpiece a significant standoff distance so as to avoid damage from dislodged molten metal slag.

Scarfing method

A scarfing apparatus which allows a greater diagonal stand-off distance from a slab during preheating and scarfing is disclosed. The apparatus includes a manifold and head assembly for receiving and distributing oxygen and fuel gas. Upper and lower preheat blocks extend from the manifold and head assembly. The blocks are spaced to define an oxygen scarfing slot and discharge orifice of predetermined size for receiving a flow of scarfing oxygen from the manifold and head assembly. A plurality of preheat nozzle inserts are mounted within the upper preheat block adjacent to each other in a row substantially across the width of the upper preheat block. Each nozzle insert includes a central bore through which a flow of oxygen is received from the manifold and head assembly and discharged through the insert. Longitudinally extending, substantially parallel flutes are positioned on the outer surface of the nozzle inserts and form fuel gas flow channels which receive fuel gas from the manifold and head assembly and deliver the fuel gas in a substantially parallel, concentric flow around the central flow of oxygen to prevent a sharp fuel gas flow intersection with the oxygen to maintain the momentum of the oxygen adjacent the nozzles as it exits the central bore. The nozzle inserts may be readily replaced when damaged. A method of initiating preheating of a slab with the scarfing apparatus of the present invention also is disclosed.

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Florence, SC, United States of America

John G Dawson, Jr