Classifications

• • 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

Definitions

• the present invention is related to a cutting torch to generate from an electrode placed in the cutting torch an arc transmitted to a workpiece the said arc comprising a plasma-generating gas and being controlled by a gaseous medium which is also arranged to cool the torch.
• Cutting torches utilizing gaseous cooling medium are already known. These, however, have not been capable of coping in a satisfactory manner with the actual cutting temperatures and thereby function less efficient ⁇ ly than could be anticipated on account of, among other things, insuffi ⁇ cient cooling. These prior art cutting torches cannot for example cut thick worpieces at relatively low voltages and give a somewhat uneven cut. in the workpiece.
• the object of the present invention is to provide a cutting torch which is so well cooled by means of gaseous cooling medium that it is capable of withstanding the actual cutting temperatures without being affected and is so elaborated that the used, gaseous cooling medium contributes not only to directing of the arc but also to removal of melted material from the cutting place, whereby a more efficient and concentrated light can be generated, enabling both thicker materials to be cut and a more uniform cut to be obtained in the workpiece.
• a further object of the inven tion is to provide a cutting torch which does not need to be held at a distance from the workpiece in which a cut is to be cut without risking difficulties in passing the cutting torch over the surface of the work- piece which is to be cut.
• a large ly closed space is accomplished between the cutting torch and the work- piece by means of a heat-resistant, electrically isolated body placed in the outlet end of the cutting torch for the arc, the said body being of annular shape and with its centre placed opposite the direction of trans-
• a further advantageous embodiment of the inventive concept is - where the end sleeve is constructed of a suitable heat-con ⁇ ductive material - if according to the present invention, the annular, heat-resistant body is disposed in the opening of the end sleeve and the cooling medium is directed to flow along a not unessential part of the
• FIG. 1 shows a section through a design of a cutting torch according to the invention
• Fig. 2 shows an enlarged subsection through the cutting torch accord ⁇ ing to Fig. 1, mainly its lower part.
• •*- ⁇ * -• 19 (not shown), through which runs a supply tube 18 for a plasma-generat ⁇ ing gas 7 and a supply tube 17 for a gaseous cooling medium 8.
• plasma-generating gas 7 that can be used are argon, argon and hydrogen or nitrogen and examples of gaseous cooling medium are carbon dioxide, oxygen gas and compressed air, but obviously other suitable gases can also
• the necessary voltages and potentials respectively can be supplied through the handle 19, for example by means of an electric conductor 20 and by means of the metal casing of the supply tube 18.
• the gaseous cooling medium 8, for example oxygen gas under a certain pressure or compress * ;*-, air, supplied by means of the supply tube is first supplied to a cooling chamber 13 provided in the cutting torch, which is essentially limited by an upper casing 12 of suitable electrically conduc- QI- ⁇ tive and heat-conductive material, such as copper or brass, by an isolat ⁇ ing body 22, an isolating sleeve 16, for example of Teflon, capable of withstanding a temperature of approx. 250 C and by a guide device 23 con ⁇ sisting of electrically conductive material for a central electrode 2 placed in the latter, which electrode, for example via a screw sleeve 24 1C and a turnable button 21, is arranged to fix the electrode 2.
• the turn- able button 21 is sealed and self-locking via a seal 28 against the isola ⁇ ted body 22.
• the cooling chamber 13 opens out into a plurality of holes 15 in the isolating sleeve 16, which is fixed in an appropriate manner in the upper 1 * - * casing 12.
• a device 26 placed inside the said holes 15 is a device 26 made of an ap ⁇ intestinalte metal and provided with through-going ducts 27, relative to which a guide sleeve 9 made of a suitable electrically conducting material is fixed.
• an end sleeve 1 consisting of a suitable heat ?(, conducting material, for example copper or brass.
• the end sleeve 1 is pro ⁇ vided in its lower part - as seen in the figures - with an annular body 3, which is made to advantage of a ceramic material capable of withstand ⁇ ing high temperatures without changing shape or properties. If so deemed appropriate, the end sleeve 1 and the body 3 can obviously instead be made y- in one piece, for example of a DCamic material.
• the electrode 2 is - as evident from Fig. 1 - guided at its upper end by the guide device 23 and at a relatively large distance from there by a holed electrode guide sleeve 25, which is fixed in the guide device 23, for instance by means of threads.
• the guide device 23 is provided with -ii. a cavity to which plasma-generating gas 7 is supplied via the supply tube 18.
• This guide sleeve 9 can - if so desired
• PAD ORIGINAL or required - be fed with a high-frequency alternating current from the conductor 20 via the metal device 26 in order to facilitate ignition of the arc and with a direct voltage potential which is slightly less nega ⁇ tive than the potential of the electrode 2.
• This difference in direct vol- o--*. ⁇ *" ⁇ "£ ⁇ ? can be utilized to keep a small pilot flame burning between the elec ⁇ trode 2 and the guide sleeve 9.
• the inner surface 10 of the guide sleeve 9 - see especially Fig. 2 - and the outlet 30 throttle together the pres ⁇ surized plasma gas 7, a workpiece 4, which is to be cut with a cut 6, is fed with a positive direct voltage potential, so that the pilot flame gene
• the outer surface 11 of the guide sleeve 9 at an angle to the arc, for example directed between 15 and 75 to the latter.
• the said inner surfaces la, 3a and the said outer surface 11 are so directed that they guide the said portion 8b of the cooling medium 8 to strike the arc just before the latter hits the workpiece 4, i.e. the 5 said portion 8b of the cooling medium 8 throttles the cross section of the arc.
• the lower surface of the annular body 3 - seen in Fig. 2 - is adapted to rest tightly against the workpiece 4, so that the said portion 8b of the cooling medium 8 is forced into the melt in the workpiece 4 gene rated by the arc and thus contributes to removal of the melt in the cut 6.
• the remaining portion 8a of the cooling medium is discharged - if so required - during further cooling of the inner surface la of the end sle ⁇ eve 1 through holes 29 in the upper part of the end sleeve 1 at such a distance from the workpiece 4 that the remaining portion 8a of the cooling medium 8 does not cool the workpiece 4.
• one portion 8b of the c cooling medium may be discharged through openings running in a turning direction between the surfaces 11 and 3a so that a whirl of the one portio
• the guiding inner surface 3a of the annular body 3 extends - as is es ⁇ pecially evident from Fig. 2 - viewed in the direction of extension of
• the upper casing 12 can be fed advantageously with a potential which agrees with the potential of the workpiece 4.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Arc Welding In General (AREA)
• Plasma Technology (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20352696

Family Applications (1)

Country Status (4)

Cited By (1)

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Citations (3)

• 1983
  • 1983-09-29 SE SE8305331A patent/SE444902B/sv not_active IP Right Cessation
• 1984
  • 1984-10-01 DE DE8484903677T patent/DE3479711D1/de not_active Expired
  • 1984-10-01 EP EP84903677A patent/EP0188425B1/en not_active Expired
  • 1984-10-01 WO PCT/SE1984/000324 patent/WO1985001462A1/en active IP Right Grant

Patent Citations (3)

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