Abstract: A method and a system for the plasma arc cutting of a workpiece with automatic adaptation of the characteristics of the plasma jet by making various corrections, simultaneously and in real time, to several parameters, including the cut path.

Abstract: A plasma cutting process for cutting a metal workpiece using a plasma cutting torch supplied with electrical current and with at least plasma gas. At least one portion of the current ramp-up used at the start of cutting and/or of the current ramp-down used at the end of cutting, respectively, is slaved to the ramp-up in pressure and/or in flow rate of the gas used, at the start of cutting, and/or the ramp-down in pressure and/or in flow rate of the gas used, at the end of cutting.

Abstract: An emissive electrode insert formed from an alloy containing hafnium and zirconium. The insert typically contains at least about 80% hafnium by weight and about 0.1 to about 8% zirconium by weight. The invention also relates to a plasma torch electrode formed from an electrode body with a cavity into which such an emissive insert is fitted, to a plasma torch utilizing such an electrode, and to a plasma cutting process for cutting a steel workpiece, in which such a plasma torch is employed.

Abstract: The invention relates to a nozzle (14) for a plasma torch, in particular a plasma cutting torch, the body of which has the general shape of an axisymmetric dish and includes an outlet orifice for the plasma gas jet, comprising a first external face (18) of circular shape and diameter d2, which includes, at its centre, the axial orifice for passage of the plasma jet, and an annular second external face (17), of outside diameter d3, which peripherally borders the first face (18), where d3>d2. According to the invention, the annular second external face (17) has an concave axisymmetric profile. Plasma cutting torch equipped with such a nozzle and its use in a plasma arc cutting operation.

Abstract: The invention concerns method and a system for plasma arc cutting of a workpiece with automatic adaptation of the plasma jet characteristics by simultaneous and practically real-time correction of several parameters, in particular in the complex portions of the cutting path. The inventive method can be used for cutting out more or less complex shapes involving sharp changes of direction in the cutting path, for example when producing an acute angle or a pointed profile, or patterns of small dimensions or complex shapes forming recesses in the steel plate. The invention consists in modulating the plasma jet heat energy and kinetic energy, and the plasma arc voltage (U).

Abstract: The invention relates to a plasma arc cutting process for cutting a metal workpiece, in which a dual-gas-flow torch fitted with an electrode with an emissive insert is used, the said torch delivering a central gas stream and an annular gas stream, the said annular stream being delivered peripherally to the central gas stream, characterized in that the central gas stream contains a hydrogen-nitrogen mixture and the peripheral gas stream contains carbon dioxide. The invention also relates to a unit comprising such a torch.

Abstract: The invention relates to an emissive electrode insert formed from an alloy containing hafnium and zirconium. The insert typically contains at least 80% hafnium by weight, preferably at least 90% by weight, and 0.1 to 8% zirconium by weight, preferably 0.5 to 5% zirconium by weight. The invention also relates to a plasma torch electrode formed from an electrode body comprising a cavity into which such an emissive insert is fitted; to a plasma torch comprising such an electrode; and to a plasma cutting process for cutting a steel workpiece, in which such a plasma torch is employed.

Abstract: Protective cap for a plasma arc working torch, includes a cap body (7) having an opening (17) for the passage of plasma gas, the cap body (7) being made of at least one material of ceramic type. The ceramic is a silicon nitride or an aluminum silicate. Preferably, the ceramic cap body (7) is clad with boron nitride deposited on the external surface of the cap body, the thickness of the cladding of boron nitride being less than 3 mm. Torch provided with such a cap and its use in a steel plate plasma cutting operation.

Abstract: 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.

Abstract: Protective cap for a plasma arc working torch, includes a cap body (7) having an opening (17) for the passage of plasma gas, the cap body (7) being made of at least one material of ceramic type. The ceramic is a silicon nitride or an aluminum silicate. Preferably, the ceramic cap body (7) is clad with boron nitride deposited on the external surface of the cap body, the thickness of the cladding of boron nitride being less than 3 mm. Torch provided with such a cap and its use in a steel plate plasma cutting operation.

Abstract: Process and unit for the arc working, particularly plasma cutting, of a workpiece, in which a plasma torch is supplied with an electric current and with a gas mixture containing oxygen and nitrogen, and a plasma jet obtained by the ionization of the gas mixture by the electric current is delivered by means of the plasma torch. The concentration of nitrogen and oxygen in the gas mixture is less than 50%. The gas mixture is obtained by adding a defined amount of nitrogen or, depending on the case, oxygen immediately before the gas mixture is introduced into the torch. The amount of nitrogen or oxygen is defined according to the thickness of the workpiece, to the grade of the constituent material of the workpiece, to the desired work rate and/or to the intensity of the electric current.

Abstract: Process and unit for the arc working, particularly plasma cutting, of a workpiece, in which a plasma torch is supplied with an electric current and with a gas mixture containing hydrogen and nitrogen and/or argon, and a plasma jet obtained by the ionization of the gas mixture by the electric current is delivered by means of the plasma torch. The hydrogen concentration in the gas mixture containing hydrogen and nitrogen and/or argon is less than 50%. The gas mixture is obtained by adding a defined amount of hydrogen to nitrogen and/or argon, immediately before the gas mixture is introduced into said torch. The defined amount of hydrogen is defined according to the thickness of the workpiece, to the grade of the constituent material of the workpiece, to the desired work rate and/or to the intensity of the electric current.

Abstract: Process and unit for the arc working, particularly plasma cutting, of a workpiece, in which a plasma torch is supplied with an electric current and with a gas mixture containing hydrogen and nitrogen and/or argon, and a plasma jet obtained by the ionization of the gas mixture by the electric current is delivered by means of the plasma torch. The hydrogen concentration in the gas mixture containing hydrogen and nitrogen and/or argon is less than 50%. The gas mixture is obtained by adding a defined amount of hydrogen to nitrogen and/or argon, immediately before the gas mixture is introduced into said torch. The defined amount of hydrogen is defined according to the thickness of the workpiece, to the grade of the constituent material of the workpiece, to the desired work rate and/or to the intensity of the electric current.

Abstract: Process and unit for the arc working, particularly plasma cutting, of a workpiece, in which a plasma torch is supplied with an electric current and with a gas mixture containing oxygen and nitrogen, and a plasma jet obtained by the ionization of the gas mixture by the electric current is delivered by means of the plasma torch. The concentration of nitrogen and oxygen in the gas mixture is less than 50%. The gas mixture is obtained by adding a defined amount of nitrogen or, depending on the case, oxygen immediately before the gas mixture is introduced into the torch. The amount of nitrogen or oxygen is defined according to the thickness of the workpiece, to the grade of the constituent material of the workpiece, to the desired work rate and/or to the intensity of the electric current.

Abstract: A process and an automatic installation for plasma-jet marking and for cutting or welding various materials. A carrying structure carries both a plasma-marking torch and at least one torch for plasma or laser cutting, oxycutting or plasma or laser welding. A drive system make it possible to move the torches in one or more directions of motion, and control means make it possible to control the movement of the torches relative to the workpieces to be marked. The torches are supplied with coolant, such as demineralized water, with a plasma gas or gas mixture, and with electric current. The plasma-marking installation according to the invention can be used for marking metals, metal alloys or plastics.

Abstract: A plasma torch provided with an electrode (1) having an approximately cylindrical or frustocylindrical elongate shape, the electrode (1) including at least one recess (9) made in at least part of its external peripheral wall (15). In order to deflect and guide the gas flux entering the plasma torch, the recess (9) in the electrode (1) lies opposite the orifice or orifices (7) for introducing or injecting the gas flux into the torch.

Abstract: The plasma torch head comprises an axial electrode (10) with a flat end surface (16) associated with a cup-shaped peripheral nozzle (12). The bottom (20) of the nozzle (12) comprises an axial conduit (22) for ejection of the plasma jet, and its lateral wall (24) surrounds the electrode (10) and delimits with this latter a substantially annular supply space (26). The torch head comprises structure (38) for the flow of a plasmagenic gas in the annular supply space (26) in a substantially axial direction. The end surface (16) of the electrode (10) delimits with the bottom (20) of the nozzle (12) an annular space (29) for lamination of the flow of the plasmagenic gas. For use in plasma cutting torches.

Abstract: A plasma cutting torch has a torch body comprising an electrode and a nozzle, and structure for mounting and connecting the torch body. It further comprises a torch support (A) defining a first series of fluid passages (7, 8, 10, 4, 47, 50, 54) connectable to respective circuits of fluids and a first bearing surface (9); a unitary assembly of torch body (B) comprising the electrode (28, 280) and the nozzle (36) and comprising a second series of fluid passages (25, 27, 38, 39, 42, 48, 49, 55, 56) and a second bearing surface (21); and a quick coupling (D) to assemble the assembly of the torch body to the support for the torch body with the first and second bearing surfaces bearing axially against each other and with the passages of the first series communicating with the respective passages of the second series.

Abstract: A cap for an arc torch comprises a skirt (10) composed of plastics material having a generally annular shape and surrounding and spaced from the nose (2, 7) of the torch, and a tubular nose-piece (12) composed of refractory material fitted in the free end of the skirt. The arc torch can be applied to plasma-arc cutting torches.

Abstract: Arc torch for plasma arc cutting or welding comprising an interchangeable cartridge comprising an electrode and a nozzle, and connecting elements between the cartridge and the body of the arc torch to axially insert and remove the cartridge by a purely rectilinear movement. The arc torch can be used as part of a machine comprising a station for extracting used cartridges and a station for loading new cartridges into the arc torch.