WO2003070413A1 - Procede d'oxycoupage plasma des metaux ferreux - Google Patents
Procede d'oxycoupage plasma des metaux ferreux Download PDFInfo
- Publication number
- WO2003070413A1 WO2003070413A1 PCT/FR2003/000156 FR0300156W WO03070413A1 WO 2003070413 A1 WO2003070413 A1 WO 2003070413A1 FR 0300156 W FR0300156 W FR 0300156W WO 03070413 A1 WO03070413 A1 WO 03070413A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- nozzle
- cutting
- jet
- plasma
- gas flow
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K10/00—Welding or cutting by means of a plasma
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/34—Details, e.g. electrodes, nozzles
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/34—Details, e.g. electrodes, nozzles
- H05H1/3452—Supplementary electrodes between cathode and anode, e.g. cascade
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H1/00—Generating plasma; Handling plasma
- H05H1/24—Generating plasma
- H05H1/26—Plasma torches
- H05H1/32—Plasma torches using an arc
- H05H1/34—Details, e.g. electrodes, nozzles
- H05H1/3457—Nozzle protection devices
Definitions
- the present invention relates to a process for thermal cutting of unalloyed or low alloyed steels, typically containing less than 5% by mass of alloying elements, by a jet of cutting oxygen associated with annular heating by plasma arc.
- the document WO-A-00/37207 describes a thermal cutting process, in which a jet of annular electric arc plasma, of regulated intensity, is established between an electrode hollowed out in its center, so as to form a channel , cutting gas, usually oxygen, and the workpiece.
- the electrode may or may not include an emissive insert, for example made of hafnium or tungsten depending on whether the plasr ⁇ agene gas used is respectively oxidizing like oxygen or air, or neutral like argon or nitrogen.
- the plasma arc is used to locally bring the workpiece to a temperature sufficient for the combustion reaction of iron in oxygen to begin, this step being known as the priming or preheating step.
- the part After localized heating of the part by the plasma jet and initiation of the reaction elicited, the part is pierced by the dynamic action of the cutting oxygen jet supplied by the central channel arranged in the electrode, which oxygen jet cutter ejects the molten metal under the workpiece. This step is called drilling.
- the central channel of the electrode has a convergent-divergent profile so that the oxygen jet at the outlet of the nozzle is at supersonic speed and at pressure adapted to ambient pressure, these characteristics allowing an efficient ejection of the molten metal.
- the plasma arc is confined between the central oxygen jet leaving the central channel of the electrode and the walls of the orifice of the nozzle arranged opposite the electrode in such a way that the central channel of the the electrode and the orifice of the nozzle are coaxial.
- the actual cutting of the part is obtained by relative movement of the part which has just been pierced and of the oxygen-plasma cutting torch.
- the intensity of the arc current can be reduced to a value just sufficient to maintain the oxy-combustion reaction.
- the nozzle and the electrode are cooled by internal circulation of heat transfer fluid, such as water or air, to avoid their deterioration too quickly due to thermal stresses.
- heat transfer fluid such as water or air
- the attachment of the electric arc is preferably done near the end stop of the cutting channel of the electrode. This edge heats up, oxidizes and erodes under the action of the arc foot, which degrades the quality and symmetry of the cutting oxygen jet, therefore degrades the quality of the cutting edges.
- the plasma jet is entrained, by a venturi effect, by the supersonic oxygen jet and the anode arc foot preferably hooks onto the upper edge of the cutting groove which is degraded by this additional fusion.
- the solution of the invention is then a method of implementing a plasma-cutting oxygen installation of a metal part containing at least one ferrous material, in particular iron, comprising:
- a central nozzle for delivering a cutting gas flow containing oxygen, said cutting gas flow passing inside said central nozzle,
- an intermediate nozzle acting as an electrode arranged coaxially with the central nozzle, for delivering a first jet of annular plasma gas, said first jet of annular plasma gas traveling in the space between the central nozzle and said intermediate nozzle,
- a peripheral nozzle for delivering a second jet of annular plasma gas, arranged coaxially with the intermediate nozzle, said second jet of plasma annular gas traveling in the space situated between the intermediate nozzle and peripheral nozzle, in which:
- a localized preheating of a priming zone of a metal part to be cut is carried out by subjecting said priming zone to at least one jet of preheating plasma, said plasma formed by an electric arc established in a flux gaseous produced by combining the first jet of annular plasma gas and the second jet of annular plasma gas,
- step (b) at least part of the priming zone at least preheated in step (a) is subjected to the cutting gas flow containing oxygen delivered by the central nozzle,
- step (c) drilling is carried out over the entire thickness of the part to be cut, in at least part of the initiation zone subjected to preheating in step (a), by melting and / or by combustion of the ferrous material contained in said metal part by reaction of said ferrous material under the effect of the oxidizing gas flow and the plasma jet, (d) the plasma jet and the oxidizing gas flow are simultaneously displaced along a cutting trajectory to make a cutting groove through said piece by melting and / or by combustion of the ferrous material contained in the metal piece at least by reaction of said ferrous material with at least said oxidizing gas flow, and in which the nozzle is electrically isolated from the electrode and from any part of the installation at the same potential as the electrode.
- the method of the invention may include one or more of the following technical characteristics:
- step (c) The drilling carried out in step (c) is obtained by reaction of said ferrous material with at least said oxidizing gas flow or with said plasma jet.
- step (c) the intensity of the arc current, during the ignition phase of step (a) and drilling of step (c), is adjusted to a value between 1 and 1000 A.
- the priming zone is preheated in step (a) to a temperature between 1000 ° C and 1500 ° C, preferably from 1200 ° C to 1400 ° C, more preferably of the order of 1300 ° C at 1350 ° C.
- the preheating time is between 0.001 and 2 seconds, preferably 0.01 and 1.5 seconds.
- the oxidizing gas flow is oxygen or a gas mixture containing oxygen, in particular air or air enriched with oxygen. - during cutting, each portion of the cutting trajectory is subjected to the plasma jet and to the oxidizing gas flow, most of the melting and / or combustion of the material along said cutting trajectory being ensured mainly by reaction of the iron with the oxidizing gas flow.
- the plasma jet and the oxidizing gas flow are delivered coaxially or convergently.
- the cutting groove is made by displacement at an approximately constant cutting speed of said plasma jet and oxidizing gas flow relative to the metal part.
- the first annular plasma jet delivered by the intermediate nozzle and the second annular plasma jet delivered by the peripheral nozzle are non-oxidizing gases or gas mixtures, preferably argon, nitrogen or helium, or their mixtures.
- the intermediate nozzle acting as an electrode comprises an annular emissive insert of refractory material, preferably of tungsten comprising an additive.
- the central nozzle, the intermediate nozzle and the peripheral nozzle are concentric and coaxial.
- the central nozzle is made of an insulating material, preferably a ceramic based on alumina or silicon nitride.
- the electric arc used to generate the plasma jet is established between the electrode and the part to be cut during the priming and drilling phases, then established between the electrode and the nozzle during the cutting phase.
- the invention is therefore based on a separation of the functions for hooking the arc by the electrode 2, on the one hand, and for supplying oxygen by the nozzle 1, on the other hand part, by electrically insulating the nozzle 1 from the electrode 2 and from any part of the installation at the same potential as the electrode.
- a nozzle made of a conductive material for example an alloy based on copper or zinc
- an insulating material for example a plastic or a ceramic
- a nozzle made of insulating material preferably a ceramic, for example a ceramic based on silicon nitride or a ceramic based on alumina.
- a first annular flow of plasma gas 13 between the nozzle 1 and the electrode 2 while injecting a second flow of plasma gas 11 between the electrode 2 and the nozzle. 3.
- the injection of the plasma gas flows 11, 13 can be carried out in a vortex mode, more or less marked, or purely axial so as to control the rotation of the cathode arc foot on the surface of the annular electrode and to stabilize the plasma column.
- the direct current generator can be used in so-called “direct” polarity, as shown diagrammatically in FIG. 2, that is to say with the work piece connected to the positive pole (+) of the generator and the work in place of anode, or, conversely, in polarity called “indirect”, that is to say with the work piece connected to the negative pole (-) of the generator, the work piece taking place then cathode.
- the drilling of the workpiece 8 is obtained by first maintaining the arc plasma established between the nozzle 2 and the workpiece 8 for a period of between 0.01 and 20 seconds, preferably between 0.1 and 2 seconds , for example approximately 0.5 seconds, then at the end of said duration and at an instant immediately before the start of the cutting operation proper, of the closing of the contact 5 and of the opening of the contact 6 so as to make a blown arc plasma. Cutting is then continued by heating the work piece only with this jet of blown arc plasma.
- the transfer of energy to the workpiece is more evenly distributed around the cutting groove and the upper edge of the cutting groove has an improved profile, the fusion of the cut is reduced, that is, the angle between the surface of the sheet and the cutting face is closer to the right angle.
- a cathode 2 comprising an annular emissive insert 9 made of refractory material, such as tungsten, preferably made of tungsten comprising an additive, said additive chosen from lanthanum hexaboride (LaB 6 ) or rare earth oxides such as thorium oxide (Th0 2 ), cerium oxide (Ce0 2 ), lanthanum oxide (La 2 0 3 ), driumttrium oxide (Y 2 0 3 ) or zirconium oxide (Zr0 2) , said additive in a concentration of less than 5% by weight, preferably from 0.05% to 3%, for example around 2%.
- the plasma gases 11 and 13 are non-oxidizing gas or gas mixtures, preferably neutral or inert gases, such as argon, nitrogen or helium, used alone or as a mixture.
- the regulation and the regulation of the intensity of the arc plasma current is done according to the thickness of the workpiece, the nature of the material of the workpiece, the cutting speed, the height the cutting torch and the phase in which the cycle is located.
- the intensity of the arc current during the ignition and drilling phase to a value between 1 and 1000 amperes, for example from 7 to 100 A for thicknesses of 1 and 2000 mm, 15 to 30 A for thicknesses between 10 and 100 mm.
- a value between 1 and 1000 amperes for example from 7 to 100 A for thicknesses of 1 and 2000 mm, 15 to 30 A for thicknesses between 10 and 100 mm.
- the intensity of the arc current during the cutting phase is also adjusted to a value between 1 and 1000 A, for example from 5 to 100 A for thicknesses of 1 and 2000 mm, or from 10 to 20 A for thicknesses of 10 and 100 mm. Thus, one can choose an intensity of 14 A for a piece of 80 mm.
- the arc plasma jet is stabilized and controlled independently of the cutting oxygen jet which retains its characteristics over time, independently of the state of wear of the electrode.
- a refractory electrode can be used in a neutral atmosphere because thus the service life of the electrode is significantly increased, the consistency of the quality of cut is improved.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Plasma & Fusion (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Mechanical Engineering (AREA)
- Arc Welding In General (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03712260A EP1480776A1 (fr) | 2002-02-20 | 2003-01-17 | Procede d oxycoupage plasma des metaux ferreux |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR0202140A FR2836079B1 (fr) | 2002-02-20 | 2002-02-20 | Procede d'oxycoupage plasma des metaux ferreux |
FR02/02140 | 2002-02-20 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2003070413A1 true WO2003070413A1 (fr) | 2003-08-28 |
WO2003070413A8 WO2003070413A8 (fr) | 2004-10-21 |
Family
ID=27636336
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/FR2003/000156 WO2003070413A1 (fr) | 2002-02-20 | 2003-01-17 | Procede d'oxycoupage plasma des metaux ferreux |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP1480776A1 (fr) |
FR (1) | FR2836079B1 (fr) |
WO (1) | WO2003070413A1 (fr) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3246115A (en) * | 1963-06-03 | 1966-04-12 | Giannini Scient Corp | Arc compounded combustion and flame arrangement |
FR2171469A5 (fr) * | 1972-02-01 | 1973-09-21 | Air Liquide | |
US5247152A (en) * | 1991-02-25 | 1993-09-21 | Blankenship George D | Plasma torch with improved cooling |
DE4407913A1 (de) * | 1993-03-29 | 1994-10-06 | Soudure Autogene Francaise | Plasmabrenner und Verfahren zur Durchführung, insbesondere für das Aushöhlen von Werkstücken |
WO2000037207A1 (fr) * | 1998-12-22 | 2000-06-29 | La Soudure Autogene Française | Procede d'oxycoupage avec prechauffage par plasma de materiaux ferreux, tels les aciers de construction |
-
2002
- 2002-02-20 FR FR0202140A patent/FR2836079B1/fr not_active Expired - Fee Related
-
2003
- 2003-01-17 EP EP03712260A patent/EP1480776A1/fr not_active Withdrawn
- 2003-01-17 WO PCT/FR2003/000156 patent/WO2003070413A1/fr not_active Application Discontinuation
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3246115A (en) * | 1963-06-03 | 1966-04-12 | Giannini Scient Corp | Arc compounded combustion and flame arrangement |
FR2171469A5 (fr) * | 1972-02-01 | 1973-09-21 | Air Liquide | |
US5247152A (en) * | 1991-02-25 | 1993-09-21 | Blankenship George D | Plasma torch with improved cooling |
DE4407913A1 (de) * | 1993-03-29 | 1994-10-06 | Soudure Autogene Francaise | Plasmabrenner und Verfahren zur Durchführung, insbesondere für das Aushöhlen von Werkstücken |
WO2000037207A1 (fr) * | 1998-12-22 | 2000-06-29 | La Soudure Autogene Française | Procede d'oxycoupage avec prechauffage par plasma de materiaux ferreux, tels les aciers de construction |
Also Published As
Publication number | Publication date |
---|---|
EP1480776A1 (fr) | 2004-12-01 |
WO2003070413A8 (fr) | 2004-10-21 |
FR2836079A1 (fr) | 2003-08-22 |
FR2836079B1 (fr) | 2004-04-02 |
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