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EP2022300A2 - Dispositif de découpage au plasma - Google Patents

Dispositif de découpage au plasma

Info

Publication number
EP2022300A2
EP2022300A2 EP07734474A EP07734474A EP2022300A2 EP 2022300 A2 EP2022300 A2 EP 2022300A2 EP 07734474 A EP07734474 A EP 07734474A EP 07734474 A EP07734474 A EP 07734474A EP 2022300 A2 EP2022300 A2 EP 2022300A2
Authority
EP
European Patent Office
Prior art keywords
electrode
nozzle
stop means
shoulder
shoulder means
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP07734474A
Other languages
German (de)
English (en)
Inventor
Giorgio Bassi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tecmo SRL
Original Assignee
Tecmo SRL
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 Tecmo SRL filed Critical Tecmo SRL
Publication of EP2022300A2 publication Critical patent/EP2022300A2/fr
Withdrawn legal-status Critical Current

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
    • H05H1/3442—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
    • H05H1/3478—Geometrical details
    • 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
    • H05H1/3489—Means for contact starting

Definitions

  • the present invention relates to devices for generating a plasma jet fit, for example, for cutting and in particular refers to a plasma cutting device with pneumatic contact striking, of torch type, which can be handled manually or can be associated with a robotized arm or with an automatic machine.
  • plasma torch devices equipped with an electrode and a nozzle, the first positioned in the second and both placed at respective electrical potentials.
  • the electrode and the nozzle are mutually separated by an interspace crossed by a gas flow, usually air flow, a part of which is fit to form the plasma jet coming out from a hole of the nozzle and fit for cutting metallic pieces placed at a different electrical potential.
  • the jet striking is provoked by pneumatic actuating means that, translating the electrode from a contact condition with the nozzle to a separation condition from this latter, make an electric sparkle in the gas flow between the electrode and the nozzle.
  • the contact between the electrode and the nozzle occurs in correspondence of the inner end of the hole made in the nozzle for the plasma exit.
  • the nozzle and its plasma hole are protected from the destructive effect of the plasma from a layer constituted by a second gas portion, which is not ionized, and interposed between the jet and the hole wall, by protecting it.
  • a drawback of said known devices with contact pneumatic striking consists in that the striking sparkles rapidly cause deformations and irregularities of the surface of the nozzle adjacent to the inner end of the nozzle hole for the plasma; such deformations and irregularities provoke perturbations of the protection flow constituted by the second part of the air provoking the premature wear of the nozzle and deviations and/or instability of the plasma dart trajectory.
  • a further drawback of said known devices consists in that, in order to partially compensate the thermal excesses caused, as an example, by the perturbations and irregularity of the plasma dart, they are equipped with nozzles and electrodes realized with wide thickness and large amount of material provoking weight increases, encumbrances, costs and counter-productive thermal conduction towards inner parts of the known devices.
  • An object of the present invention is to propose a plasma cutting device in which the contact striking does not compromise the surface regularity of the nozzle near to the hole and does not cause any damn and premature wear of the same nozzle and its contiguous parts.
  • Another object is to propose a device that can be cooled also when the plasma dart is switched off.
  • a further object is to propose a device light, with little encumbrance and whose inner portions are not overheated.
  • Another object is to propose a device very efficient and having a low air or gas consumption.
  • figures 1 and 2 illustrate schematic views partially sectioned of a nozzle and an electrode of the plasma cutting device object of the present invention respectively in a rest condition and an operational condition;
  • FIG. 3 and 4 illustrate schematic views partially sectioned of a first variant of the device of figures 1 and 2 at the same rest and operational conditions and;
  • figures 5 and 6 illustrate schematic views partially sectioned of a second variant of the device of figures 1 and 2 at the same rest and operational conditions and;
  • - figures 7 and 8 illustrate schematic views partially sectioned of a third variant of the device of figures 1 and 2 at the same operational and rest conditions.
  • the device 1 has an hollow nozzle 3, equipped of a passing hole 4 for the plasma exit obtained from the ionization of flow gas portion, for instance air, flowing into the cavity.
  • an electrode 2 is housed, placed to a different electrical potential with respect to the nozzle, and moved by a translation means, not illustrated being known as an example with pneumatic piston, between a rest condition R and an operational condition O in which the electrode 2 and the nozzle 3 is respectively in contact and spaced.
  • a translation means not illustrated being known as an example with pneumatic piston
  • the diameter DTE of the end portion of the electrode 2 is comprised between 2 and 15 ; times, preferably approximately 7,5 times the minimal dimension M of hole 4 and the diameter DTC of the end portion of the nozzle cavity 3 is comprised between 3 and 20 times, preferably approximately 9 times, the minimal dimension M of hole 4.
  • the length LE of the electrode 2 is comprised between 1,5 and 11 times its own end diameter DTE and the length LC of the nozzle cavity 3 is comprised between 1,5 and 11 times its own end diameter DTC; in particular such lengths of the device of figures 1 and 2 are equal to approximately 2,5 - 3 times the respective end diameters.
  • the electrode 2 and the nozzle 3 are equipped with stop means respectively first 5 and second 6 specifically fit to realize the mutual contact between the electrode 2 and the nozzle 3 at the rest condition R.
  • Said stop means first 5 and second 6 are positioned, in the operational condition O, at a minimal distance D from the passing hole 4 equal at least two times the minimal dimension M of the hole.
  • the stop means first 5 and second 6 are placed on the cylindrical side surfaces external of the electrode 2 and internal of the nozzle 3 at a distance from the plasma hole 4 equal at least 6 times said minimal dimension M of the hole that is at a distance approximately equal to at least the end diameter of the electrode 2.
  • the invention provides that minimal distance DME between the first stop means 5 and the end extremity of the electrode 2 is comprised between 1/20 and 19/20 of the length LE of the electrode 2 and that the minimal distance DMC between the second stop means 6 and the end extremity of the nozzle cavity 3 is comprised between 1/20 and 19/20 of the length LC of the nozzle cavity 3.
  • the stop means first 5 and second 6 comprise respective shoulder means 7, 8 fit for mutually matching at the rest condition R in order to realize, in such condition, the contact between the electrode 2 and the nozzle 3.
  • the shoulder means 7, 8 of the stop means 5, 6, are shaped as circular crown or truncated- conical wall.
  • the shoulder means 7, 8 of the stop means 5, 6 preferably have the same shape of truncated conical wall with respective solid angles A, B having almost the same value.
  • the invention provides that such solid angles can be different, as an example the solid angle A of the shoulder means 7 of the electrode can be smaller than the other B.
  • the shape of shoulder means 7, 8 can be different, as an example ogival, polyhedric with spherical or curve sector surface.
  • the solid angles A, B defined by shoulder means first 7 and second 8 are comprised between 40° and 180° and preferably, as in the embodiment illustrated in figure 1 and 2, they are approximately equal and like to approximately 90°. Said angles A, B have a common bisectrix almost coinciding with the longitudinal axis of the electrode and the nozzle.
  • the shoulder means 7 of the first stop means 5 form a narrowing of the electrode 2 diameter in the direction of the gas flow and the shoulder means 8 of second stop means 6 form a narrowing of the nozzle cavity 3.
  • electrode 2 Starting from the end extremity and proceeding towards the direction opposite to the gas flow, electrode 2 has a cylindrical end portion with smoothed edge, the truncated-conical shoulder means 7 with apex towards the flow direction, a portion 9 of approximately cylindrical shape with diameter greater with respect to that end cylindrical downstream to the shoulder means 7, a portion of the approximately truncated conical shape 11 with apex upstream to the flow and joined together with a further approximately cylindrical shaped portion 12 ending with a screw connection for the translation means.
  • the nozzle cavity 3 has a cylindrical end portion with smoothed edge, the corresponding truncated conical shoulder means 8 with apex towards the flow direction, and a cylindrical portion 10 having a diameter greater than the end portion provided with a removable connection to the device.
  • the electrode 2 and the nozzle 3 have corresponding lightening 13, 14, consisting in concave lateral zones of material removal, fit to reduce the device weight and to reduce the propagation of the heat from the zone of formation of the dart towards the other device parts.
  • the stop means first 5 and second 6, with the corresponding shoulder means 7, 8, are obtained, as an example by turning, in a single body respectively with the electrode 2 and the nozzle 3.
  • the invention provides that one or both stop means first 5 and second 6 are constituted by one or more elements protruding to the outside of the electrode 2 and to the inside of the nozzle 3 and irremovably fixed thereto or, preferably, removably for its substitution.
  • the invention provides that at least one of shoulder means 7, 8 of stop means first second 5 and/or 6 is equipped with grooves or relieves, not illustrated, fit to allow the gas flow also in the rest condition R allowing the cooling of the electrode and the nozzle also in such condition therefore avoiding the risk of thermal excesses.
  • the relieves can eventually be conformed to facilitate the formation of the plasma spark and are disposed radially or tilted to an helicoidal gas flow.
  • the operation of device 1 provides that the superficial damages of the electrode and the nozzle in the formation zone of the sparkles for the plasma primer are distributed on wide surface and are far from the plasma hole.
  • the end portion of the electrode 2 is cylindrical portion shaped with rounded edge as in the embodiment of figures 1 and 2 while the end portion of the nozzle cavity 3 is approximately ogival or conical shaped in order to facilitate the restoration of the correct regular gas flow.
  • the variant of figures 5 and 6 of the device 1 differs for the greater length of the electrode and the nozzle that are equal to approximately 4 - 5 times the corresponding diameters.
  • the variant of the figures 7 and 8 of the device 1 differs for the smaller length of the electrode and the nozzle that are equal to approximately 1,5 - 2 times the respective diameters.
  • An advantage of the present invention is to supply a plasma cutting device with contact striking having a nozzle and an electrode of long duration and virtually free from perturbation and instability of the plasma dart.
  • Another advantage is to supply a light, small size device and whose inner portions are not overheated.

Landscapes

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

Abstract

Dispositif de découpage au plasma par impact pneumatique, comportant au moins une buse creuse (3) dotée d'un trou passant (4) par lequel s'échappe le plasma obtenu à partir d'un gaz s'écoulant dans une cavité contenant une électrode (2) déplacée par un moyen de translation entre une position de repos (R) et une position fonctionnelle (O) dans lesquelles l'électrode (2) et la buse (3) sont respectivement au contact et espacées l'une de l'autre. L'électrode (2) et la buse (3) sont respectivement équipées de premier (5) et deuxième (6) moyens de butée espacés pour assurer le contact mutuel entre l'électrode (2) et la buse (3) dans l'état de repos (R). L'électrode (2) et la buse (3) sont placées, dans la position fonctionnelle (O), à une distance (D) du trou passant (4) égale à deux fois au moins la dimension minimale (M) de celui-ci.
EP07734474A 2006-05-04 2007-05-03 Dispositif de découpage au plasma Withdrawn EP2022300A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000332A ITBO20060332A1 (it) 2006-05-04 2006-05-04 Dispositivo per taglio al plasma
PCT/IB2007/001157 WO2007129194A2 (fr) 2006-05-04 2007-05-03 Dispositif de découpage au plasma

Publications (1)

Publication Number Publication Date
EP2022300A2 true EP2022300A2 (fr) 2009-02-11

Family

ID=38668139

Family Applications (1)

Application Number Title Priority Date Filing Date
EP07734474A Withdrawn EP2022300A2 (fr) 2006-05-04 2007-05-03 Dispositif de découpage au plasma

Country Status (3)

Country Link
EP (1) EP2022300A2 (fr)
IT (1) ITBO20060332A1 (fr)
WO (1) WO2007129194A2 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8513565B2 (en) 2008-04-10 2013-08-20 Hypertherm, Inc. Nozzle head with increased shoulder thickness
CN102596478B (zh) * 2009-11-04 2014-12-17 株式会社安川电机 非消耗电极式弧焊设备
US8901451B2 (en) * 2011-08-19 2014-12-02 Illinois Tool Works Inc. Plasma torch and moveable electrode
US10743399B2 (en) * 2014-09-16 2020-08-11 The Esab Group, Inc. Reducing restart cycle time of a plasma blow back torch for improved marking
IT201600081330A1 (it) * 2016-08-02 2018-02-02 Cebora Spa Torcia al plasma con accensione a contatto
EP4062717A1 (fr) * 2019-11-19 2022-09-28 Hypertherm, INC. Conceptions des consommables pour chalumeau à jet de plasma

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4018423A1 (de) * 1990-06-08 1991-12-12 Inst Zavaryavane Plasmatron fuer das brennschneiden von metallen
US6403915B1 (en) * 2000-08-31 2002-06-11 Hypertherm, Inc. Electrode for a plasma arc torch having an enhanced cooling configuration
US6933461B2 (en) 2001-02-27 2005-08-23 Thermal Dynamics Corporation Tips and contact members having ridges for use in a contact start plasma arc torch
US7202440B2 (en) 2003-11-24 2007-04-10 Thermal Dynamics Corporation Dual mode plasma arc torch
ITBO20030016A1 (it) 2003-01-14 2004-07-15 Cebora Spa Torcia al plasma ad accensione per contatto.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2007129194A2 *

Also Published As

Publication number Publication date
WO2007129194A2 (fr) 2007-11-15
ITBO20060332A1 (it) 2007-11-05
WO2007129194A3 (fr) 2008-07-17

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