Oxygen arc cutting with plasma pre-heating of ferrous materials, such as structural steel workpieces

An installation and a method for oxygen arc cutting of a metal workpiece containing at least a ferrous material, in particular a structural steel workpiece, which consists in: pre-heating locally a priming zone of the metal workpiece to be cut by subjecting the priming zone to a plasma jet; then in producing a localized fusion and/or combustion of the ferrous material contained in the workpiece, using the plasma jet or a combination of the plasma jet and an oxidizing gas flow to obtain a perforation along the whole thickness of the metal workpiece; once the perforation has been obtained, in synchronously displacing, the plasma jet and the oxidizing gas flow along a cutting path to produce a predefined slit through the metal workpiece.

The invention will now be described in greater detail with the aid of examples of embodiments shown schematically in the appended figures, which are given by way of illustration but imply no limitation.

FIG. 1

a shows a diagram of a first embodiment of a unit according to the invention of the type with convergent jets.

1. A process for the plasma oxycutting of at least one metal workpiece containing at least one ferrous metal, in particular iron, in which:

2. The process as claimed in claim 1, characterized in that the drillhole produced in step (c) is obtained by the reaction of said ferrous material with at least said stream of oxidizing gas.

3. The process as claimed in claim 1, characterized in that the drillhole produced in step (c) is obtained by the reaction of said ferrous material with said plasma jet.

4. The process as claimed in claim 1, characterized in that the stream of oxidizing gas is oxygen or a gas mixture containing oxygen, especially air or oxygen-enriched air.

5. The process as claimed in claim 1, characterized in that, during cutting, each portion of the cutting path is subjected to the plasma jet and to the stream of oxidizing gas, most of the melting and/or combustion of the material in said cutting path being essentially provided by the reaction of iron with the stream of oxidizing gas.

6. The process as claimed in claim 1, characterized in that the plasma jet and the stream of oxidizing gas are delivered coaxially or convergently.

7. The process as claimed in claim 1, characterized in that the kerf is produced by moving said plasma jet and said stream of oxidizing gas at an approximately constant cutting rate, relative to the metal workpiece.