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WO1997033458A2 - Dispositif a plasma pour couper des metaux - Google Patents

Dispositif a plasma pour couper des metaux Download PDF

Info

Publication number
WO1997033458A2
WO1997033458A2 PCT/CZ1997/000011 CZ9700011W WO9733458A2 WO 1997033458 A2 WO1997033458 A2 WO 1997033458A2 CZ 9700011 W CZ9700011 W CZ 9700011W WO 9733458 A2 WO9733458 A2 WO 9733458A2
Authority
WO
WIPO (PCT)
Prior art keywords
casing
electrode
metal sleeve
insert
tubular
Prior art date
Application number
PCT/CZ1997/000011
Other languages
English (en)
Other versions
WO1997033458A3 (fr
Inventor
Emil Markovich Rudyak
Yevgenyi Emilyevich Rudyak
Original Assignee
Interplazma, Spol. S R.O.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Interplazma, Spol. S R.O. filed Critical Interplazma, Spol. S R.O.
Publication of WO1997033458A2 publication Critical patent/WO1997033458A2/fr
Publication of WO1997033458A3 publication Critical patent/WO1997033458A3/fr

Links

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
    • 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
    • H05H1/3421—Transferred arc or pilot arc mode
    • 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
    • H05H1/3442—Cathodes with inserted tip
    • 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
    • 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
    • H05H1/3468—Vortex generators

Definitions

  • This invention relates to a metal-working device, more specifically - it is a device for plasma cutting of metals using an incisive electric arc.
  • the device may be used for welding, melting down, and surfacing of metals.
  • the invention can be used effectively to cut metal from any distance, including the direct contact with a metal that is uneven and deformed, and has hollows and fractures in the surface.
  • This invention makes it possible to ensure effective, continuous work without needing to extinguish the electric arc during the move of cutting from one workpiece to another, i.e. during cutting of grids or sheets placed some distance from each other.
  • the proposed device may be used with high efficiency both for cutting metal and piercing metal, and likewise for dry cutting or underwater cutting of sheets, corners, grids and uneven workpieces with sharp projections and hollows.
  • the plasma torch must not touch the metal workpiece as this leads to double arcing and to the burning of the device itself;
  • molten metal sprinkles must not fall on the nozzle or on the casing of the torch. This leads to double arcing and to the device itself buixting. Intensive metal sprinkles appear when the arc is heated or when the metal is pierced.
  • One of the known designs of the plasma torch for cutting of metals (US Patent No. 4861969) consists of casing, electrode, nozzle and conducting protective shield, fixed on the casing and surrounding the nozzle with a gap. There is an outlet opening in the shield, placed coaxially with the nozzle opening, and does not prevent the outlet of the plasma arc from this opening.
  • the device includes a dielectric insulation, insulating the shield from the casing for prevention of ⁇ ie double arcing, as well as a special device for creation of the redundant gas flow in the gap between the nozzle and the shield.
  • the disadvantage of this kind of device is the extinction of the incisive electric arc during cutting of the metal wi ⁇ surface cracks. This causes the need for repeated starting of the arc and reduces the cathode lifetime together with reduction of cutting efficiency because of the time losses for repeated heating of the arc.
  • PCT Application No. 92/15421 consists of a casing, electrode, nozzle and protective shield.
  • the outlet aperture in this design is large in comparison with the nozzle opening.
  • the disanvatage of this device is that the incisive electric arc is extinguished when metal with surface cracks is being cut.
  • plasma torches in which the electric arc discharge forms between the cadiode and the anode in the discharge chamber of the plasma torch.
  • Such devices are used as electric arc plasma generators.
  • One plasma torch with a swirl stabilisation system for the electric arc (according to the USSR Author's Certificate No. 356978) consists of a casing, a rod-like inner electrode and a tubular cooled output electrode, and a turbulence generator for swirled gas supply into the gap between the electrodes.
  • the electric arc which is stabilised by swirled gas, burns between the edge of the inner electrode and the inner surface of the turbular outlet and is parallel to it; the electric arc heats the gas flow in this channel and the plasma escapes from the outlet electrode as a high-temperature and high-speed stream of plasma.
  • the electrodes are cooled with running water.
  • Plasma torches of this type ensure that the electric arc is stable within the discharge chamber and that it is not extinguished. But plasma torches of this kind are not very efficient for metal cutting due to their low cutting speed, which is a result of the outlet plasma stream not being sufficiently hot.
  • the outlet plasma stream does not exceed 6000°C when air is the working medium, a temperature that is significantly lower than the temperature of 10000°C achieved when cutting metal using an incisive electric arc.
  • This device consists of an electric arc plasma generator casing with an inner electrode-cathode and an outlet electrode-anode with a discharge tubular channel and apertures for the supply of swirled gas into the space between the electrodes; and also a metal sleeve that is electro- insulated from the casing and surrounded by a gap, and with an aperture parallel to the tubular discharge channel of the outlet electrode and with apertures for swirled gas to be introduced into the gap.
  • This device ensures that a low-current electric arc burns continuously between the cathode and the inner surface of the tubular discharge channel of the outlet electrode-anode.
  • this device In the case of a large-current incisive arc created instantaneously and automatically due to the conductivity of the stream of plasma and which flows along the axis of the device between the metal and the cathode, this device is also capable of ensuring that the arc burns.
  • the weakness of this device is that the service life of the whole anode is limited by the lifespan of the tubular discharge channel, which ages due to the natural electric erosion that is a characteristic of all electric arc plasma generators, and that the service life of the whole electro- insulated metal sleeve is correspondingly limited by the lifespan or resistance to the heat impact on the wall with the opening coaxial to the tubular discharge channel.
  • the purpose of the current invention is to develop a device for the plasma cutting of metals that has a longer service life and that reduces the metal and labour consumption required to manufacture replaceable elements by replacing only the damaged element of the outlet electrode and the damaged element of the insulated sleeve with an opening coaxial to the tubular discharge channel.
  • the device for plasma cutting of metal includes the casing with the inner electrode, outlet electrode, equipped in the discharge tubular channel and openings for the swirled gas supply into the space between electrodes, and metal sleeve electrically insulated from the casing and placed around it at a defined distance, with an opening coaxial to the discharge tubular channel of the outlet electrode and with openings for swirled gas supply to the gap.
  • the part of the outlet electrode, where the discharge tubular channel is located is made in a form of anode copper insert, which has, for example, the thread connection with another coaxially located part of the outlet electrode, and a part of electrically insulated from the casing metal sleeve surrounding the casing with the gap, in which there is an opening coaxial with the discharge tubular channel is provided with a copper or ceramic insert, having, for example, the thread connection with another part of the metal sleeve, while the ratio between the length of the tubular channel (L) and its diameter (d) is within the range of 2 to 5.
  • Manufacturing of the anode insert with the tubular discharge channel from copper, having high heat conductance and coefficient of volume expansion, and its connection with the cooled part of the outlet electrode by the means, for example, of thread connection allows to achieve the life of anode insert not worse than the life of outlet electrode with tubular discharge channel made of the monolith copper. This may be achieved due to the anode insert design, where the ratio between the length of the tubular discharge channel and its diameter is maintained within the limit of 2 to 5. The further reduction of the lower limit of this ratio is not useful, because it causes the increase of wearing-out of the anode insert edge on the side where plasma stream blows out due to erosion of anode spots of the electric arc, glowing between the electrode and the anode insert. Exceeding of the upper limit of the ratio leads to increase of wearing our of anode insert on the side of its tubular discharge channel due to the influence of the electric arc, glowing between the metal being cut and the electrode.
  • Figure 1 shows the overall view of the device for plasma cutting of metals
  • Fig. 2 shows the anode insert.
  • the device includes casing with the inner electrode (cathode) 2 and outlet electrode (anode) 2, separated by the insulator between electrodes 4.
  • the part of the outlet electrode has an anode insert 5 with the length of L, where the discharge tubular channel 6 is placed with the diameter of d.
  • the anode insert is made of copper and is connected to another co-axially placed part of the outlet electrode 3 by the means of thread connection 7.
  • the outlet electrode 3 has openings 8 for swirled gas input into the gap between electrodes and a cavity 9 for forced hydraulic cooling.
  • the metal sleeve 10 is located around the casing 1 with a gap, covered on the upper side by the insulator 1_1 and openings 12 for swirled gas injection into the gap between the sleeve K) and the casing 1.
  • the metal sleeve 10 has a cavity 13 for the forced hydraulic cooling, and its part with an opening coaxial to discharge tubular channel - copper or ceramic insert 14 with the opening 1_5, is coaxial with the discharge tubular channel 6.
  • the insert 14 is made of copper and has a thread connection 16 with another part of the sleeve, or it is made of ceramics and may have a conic connection with another part of the sleeve.
  • the outlet electrode 3 is fitted with respect to the possibility of its connection to chp 17 of one of the positive poles of the power supply, the volt-ampere characteristics between this chp and the negative chp of the power supply 18 ensure the low current flow.
  • the workpiece 20 is connected to the chp 19 of the second positive power supply.
  • Fig. 1 shows the electric arc 21. continuously glowing between the electrode 2 and the anode insert 5 in its tubular discharge channel 6 when the device is working.
  • Position 22 shows the incisive electric arc, glowing during cutting between the workpiece 20 and
  • the device is functioning as follows: water for the forced cooling and compressed air in a swirled form are supplied through the openings 8 of the outlet electrode 3 into the space between electrodes, and through the openings 12 of the sleeve K) into the gap between the casing and the sleeve 10.
  • the inner electrode 2 has to be connected to the chp !_8 of the negative pole of power supply, the outlet electrode 3 has to be connected to the positive clip 12 for low amp and the workpiece has a connection to the positive chp 19 for high amp.
  • the short pulse of voltage from the high voltage high frequency oscillator (which is not shown on Fig.
  • the result of its electric conductance is an immediate occurrence of the electric arc, taking power from clips 18 and 19 of the power supply, and this arc glows between the inner electrode 2 and the workpiece 20 in the direction of the anode insert 5 axis, insert 14 axis, and cuts the workpiece 20.
  • the device for plasma cutting of metals was designed.
  • Parameters of continuously glowing electric arc inside the discharge tubular channel of the anode insert were as follows: Current 25 to 25 A, Voltage 150 to 160 V.
  • the temperature of plasma stream from the opening 15_ of the insert 4 was changing in dependence on air consumption and was on the level of 4000 to 5000° C.
  • the length of the plasma stream is approximately 5 cm.
  • the electric arc 22 When the device is moved to the workpiece at the distance of less than 5 centimeters, immediately and automatically occurs the electric arc 22, stabilised in the opening 1_5 of the insert 14 and penetrating into the metal with the current of 180 to 220 A and voltage 150 to 180 V.
  • the current, voltage and capacity of the arc may be regulated by the power supply, the temperature reaches 10 000°C.
  • the glow of the incisive electric arc is reliable and stable. In the case of the direct contact between the device and the metal there is not a danger of the accidental burning of the device, because the short-circuit does not occur.
  • the presence of the anode insert 5 and insert 14 in the electrically insulated metal sleeve 10 reduces the heat losses of the device with the cooling water by 6 to 8 % in comparison to the version when the outlet electrode 3 and the metal sleeve 10, which is electrically insulated from the casing 1, are made of the monolith copper. During the work the anode insert is heated to high temperature of 500 to 800°C.
  • Such a high temperature of the anode insert helps to improve the stability of the continuously glowing electric arc during the time of the pulsing speed changes of the air flow in the - o -
  • discharge channel for example in the case of piercing of the workpiece, or in the case of close and quick movement of the device during the cutting of the workpiece with projections or lugs.

Landscapes

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

Abstract

L'invention concerne un dispositif à plasma pour couper des métaux, comprenant une enceinte avec une électrode interne, une électrode de sortie avec un canal de décharge tubulaire et avec des ouvertures pour introduire un gaz tourbillonnaire dans l'espace entre les électrodes et un manchon métallique isolé électriquement de l'enceinte, placé autour de l'enceinte avec un espacement et en ayant une ouverture coaxiale avec le canal de décharge tubulaire et des ouvertures pour l'introduction du gaz tourbillonnaire. Le dispositif se caractérise en ce qu'une partie de l'électrode de sortie, dans laquelle se trouve le canal de décharge tubulaire et qui se présente sous la forme d'un élément d'insertion anodique en cuivre comprend, par exemple, un raccord fileté avec une autre partie coaxiale refroidie par l'eau (entourée par un espacement) du manchon métallique. Egalement, le manchon métallique qui a une ouverture coaxiale avec le canal de décharge annulaire, comprend une pièce d'insertion en cuivre ou en céramique qui a, par exemple, un raccord fileté avec une autre section du manchon métallique, le rapport entre la longueur tubulaire (L) et son diamètre (d) étant maintenu dans la plage allant de 2 à 5.
PCT/CZ1997/000011 1996-03-06 1997-03-05 Dispositif a plasma pour couper des metaux WO1997033458A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KZ960277 1996-03-06
KZ960277.1 1996-03-06

Publications (2)

Publication Number Publication Date
WO1997033458A2 true WO1997033458A2 (fr) 1997-09-12
WO1997033458A3 WO1997033458A3 (fr) 1997-10-30

Family

ID=19720763

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CZ1997/000011 WO1997033458A2 (fr) 1996-03-06 1997-03-05 Dispositif a plasma pour couper des metaux

Country Status (1)

Country Link
WO (1) WO1997033458A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2987967A1 (fr) * 2012-03-12 2013-09-13 Air Liquide Tuyere pour torche a plasma d'arc avec element interne demontable
US8680425B2 (en) 2004-11-16 2014-03-25 Hypertherm, Inc. Plasma arc torch having an electrode with internal passages

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA14595A (fr) * 1882-04-15 Edwin J. Houser Perfectionnements aux engrais artificiels
US4866240A (en) * 1988-09-08 1989-09-12 Stoody Deloro Stellite, Inc. Nozzle for plasma torch and method for introducing powder into the plasma plume of a plasma torch
WO1993013905A1 (fr) * 1992-01-14 1993-07-22 Hypertherm, Inc. Ajutage ameliore et procede de fonctionnement conçu pour une torche a arc de plasma

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA14595A (fr) * 1882-04-15 Edwin J. Houser Perfectionnements aux engrais artificiels
US4866240A (en) * 1988-09-08 1989-09-12 Stoody Deloro Stellite, Inc. Nozzle for plasma torch and method for introducing powder into the plasma plume of a plasma torch
WO1993013905A1 (fr) * 1992-01-14 1993-07-22 Hypertherm, Inc. Ajutage ameliore et procede de fonctionnement conçu pour une torche a arc de plasma

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8680425B2 (en) 2004-11-16 2014-03-25 Hypertherm, Inc. Plasma arc torch having an electrode with internal passages
FR2987967A1 (fr) * 2012-03-12 2013-09-13 Air Liquide Tuyere pour torche a plasma d'arc avec element interne demontable

Also Published As

Publication number Publication date
WO1997033458A3 (fr) 1997-10-30

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