WO1991005629A1 - Ajutage perfectionne pour torche a arc de plasma - Google Patents

Ajutage perfectionne pour torche a arc de plasma Download PDF

Info

Publication number
WO1991005629A1
WO1991005629A1 PCT/US1990/004112 US9004112W WO9105629A1 WO 1991005629 A1 WO1991005629 A1 WO 1991005629A1 US 9004112 W US9004112 W US 9004112W WO 9105629 A1 WO9105629 A1 WO 9105629A1
Authority
WO
WIPO (PCT)
Prior art keywords
nozzle
electrode
angle
plasma arc
kink
Prior art date
Application number
PCT/US1990/004112
Other languages
English (en)
Inventor
Nicholas A. Sanders
Original Assignee
Hypertherm, Inc.
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 Hypertherm, Inc. filed Critical Hypertherm, Inc.
Priority to DE69021736T priority Critical patent/DE69021736T2/de
Priority to EP90911719A priority patent/EP0496733B1/fr
Publication of WO1991005629A1 publication Critical patent/WO1991005629A1/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
    • H05H1/3478—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
    • H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy

Definitions

  • the present invention relates to plasma arc torches, and more particularly to an improved nozzle construction for initiating an arc in such torches utilizing a high voltage, high frequency signal applied to either an electrode or to the nozzle.
  • the oldest, and most widely used method is the high frequency, high voltage spark discharge method.
  • the high voltage, high frequency generates charge carriers which create an electrical current path in the gas in the gap between the cathode and the electrode to establish D.C. flow of current, a pilot arc discharge.
  • the electrode In prior art plasma arc torches the electrode has traditionally had a generally cylindrical configuration, whether a cylindrical disk seated in a solid copper tube as described in the aforementioned U.S. Patent Nos. 3,641,308, 4,203,022 or the electrode-nozzle arrangement shown and described in U.S. Patent Nos. 4,421,970; 4,791,268; and 4,861,962.
  • the lower end of the electrode adjacent the nozzle typically has a cylindrical configuration.
  • the immediately opposite nozzle surface typically mirrors the outer configuration of the electrode, or is smooth, conical and downwardly converging.
  • the nozzle includes a central exit port where the plasma arc exits the torch and attaches to the workpiece. It is significant that while the transition between the interior nozzle surface and the exit port may be a sharp corner, and while this corner may be closely spaced from the electrode, it is not located in a region where it is closer to the electrode than immediately adjacent portions of the nozzle.
  • Another principal object is to reduce electrode wear as compared to comparable prior art nozzles in comparable torches operated under the same conditions.
  • Yet another principal object of this invention is to reduce the breakdown potential required to initiate an arc discharge in a given plasma arc torch.
  • a further object in the present invention is to provide a nozzle construction which reduces electromagnetic interference during the high frequency, high voltage start up with other electrical and electronic components in the operating area.
  • a still further of the present invention is to provide a nozzle construction with the foregoing advantages which is simple in construction, has a comparatively low cost of manufacture, and can be used as a replacement part for conventional nozzles of existing plasma arc torches.
  • a plasma arc torch includes an electrode and a nozzle mounted in a mutually spaced relationship at one end of the torch adjacent a workpiece. They are also mounted symmetrically with respect to the torch and each other about a common longitudinal axis. A flow of an ionizable gas passes through the torch and exits a central exit port in the nozzle which is aligned opposite the lower end of the electrode.
  • a DC power supply is attached to the electrode and the nozzle and a high frequency, high voltage coil/generator is electromagnetically coupled to either the negative or positive output of the DC power supply.
  • the nozzle which is typically cup-shaped, receives the electrode within the nozzle with a generally uniform spacing between the electrode in the opposite surfaces of the nozzle.
  • the interior surface of the nozzle facing the electrode has a convex, inwardly projecting, circumferentially extending solid angle or "angle kink" portion.
  • This angle kink is characterized by a minimum radius of curvature (whether a sharp corner, a rounded corner, or even some more complex cross-sectional shape) for a narrow annular region of this surface immediately opposite to the electrode and adjacent the central exit port of the nozzle.
  • This annular region defines the location of preferential initiation of the plasma arc discharge.
  • This kink angle is located at the closest approach between the electrode and the nozzle, and is displaced from the angle formed by the intersection of the central exit port in the nozzle and the interior surface of the nozzle.
  • the angle kink is formed by the intersection of two conical surfaces having different angles of inclination with respect to the longitudinal axis. Comparatively flat angle kinks, e.g. one with an included angle of about 165° are effective.
  • the electrode also has an outwardly projecting angle kink formed by the cylindrical side surface, or a conical transition surface of the lower end of the electrode, and a planar end face oriented perpendicular to the longitudinal axis.
  • the electrode angle kink is also located at the point of closest approach between the electrode and the nozzle and it opposes the angle kink on the nozzle.
  • the electrode and nozzle angle kinks are centered in circumferentially extending annular regions.
  • Fig. 1 is a simplified schematic view of a high frequency, high voltage plasma arc initiation system according to the present invention
  • Fig. 2 is a detail view in side elevation partially in vertical section of the lower portion of the electrode and the nozzle shown in Fig. 1;
  • Fig. 3 is a view corresponding to Fig. 2 showing a prior art nozzle construction utilizing a smooth conical interior nozzle surface
  • Fig. 4 is a view corresponding to Fig. 2 of -an alternative nozzle construction according to the present invention. Detailed Description of the Preferred Embodiments
  • a plasma arc torch 10 having a nozzle 12 and an electrode 14 is connected to a DC power supply 16. As shown, the positive output of the power supply 16 is connected by lead 18 to the nozzle 12 and the negative side of the power supply 16 is connected by lead 20 to the electrode 14.
  • the plasma arc torch 10 can be any of a wide variety of currently available torch designs in the prior art. Suitable constructions are shown, example, in the aforementioned U.S. Patent Nos. 3,641,308; 4,203,022; 4,791,268; and 4,861,962.
  • a high-frequency coil 22 can be coupled electromagnetically to either the positive lead 18, as shown, or the negative lead 20.
  • the high-frequency coil/generator produces a high-voltage, high-frequency signal which is transmitted over the lead to the nozzle or the electrode.
  • the high-frequency coil generator is of well known, conventional construction, as is the DC power supply.
  • a typical high voltages produced by the coil/generator 22 are in the range typically 5,000 volts at frequencies in the range of 2 to 3 mHz.
  • a flow 24 of an ionizable gas is initiated through an electrode-nozzle chamber 25 exiting the torch through an exit port 44 in the lower face of the nozzle. It assumes a swirling flow path 24a between the lower end of the electrode and the nozzle just before it exits port 44 in the nozzle.
  • a high level oscillating electric field will be generated between the elctrode 14 and the nozzle 12,
  • a significant aspect of the present invention is that the interior surface 26 of the nozzle has circumferentially extending (closed loop) projection or peak which is termed herein an angle kink 28. It is significant this angle kink 28 is located at the point of closest spacing between the nozzle 12 and the electrode 14, and represents a line of localized minimum gap separation between the electrode and the nozzle — as compared, for example, to prior art constructions where the corner associated with the nozzle exit port may have a minimum radius of curvature, but is no closer to the electrode than adjacent portions of the surface. It has been found that this construction reduces the breakdown voltage between a narrow annular region 30 centered on the angle kink 28 and a narrow annular regio 32 centered on an electrode angle kink 34.
  • the electrode 14 has a conical tapered end surface 36 and a planar end face 38 oriented perpendicular to a common longitudinal axis 40 of the torch, the nozzle 12, and the electrode 14.
  • the intersection of the surface 36 and the end face 38 defines the angle kink 34.
  • the intersection of conical surface 26a (having an angle A of inclination of about 45° from the axis 40, as shown) and conical surface 26b (having an angle B of inclination of about 60° from the axis 40, as shown) defines the angle kink 28.
  • the angle kink therefore has an included angle of 165° and has a line intersection which is not rounded.
  • angle kinks 28 and 34 and their associated regions 30 and 32 are separated by a gap 42 in an electrode-nozzle chamber 25. While the angle kink 28 and 34 are shown as being directly opposite one another, and this is the preferred embodiment, such a precise opposite alignment is not essential to the operation of this invention.
  • the gap 42 between the angle kinks 28 and 34 is the point of closest spacing between the nozzle and the electrode, at least in the region immediately adjacent the angle kinks.
  • the application of the high frequency to the nozzle 12 over the positive lead 18 concentrates the electric field strength at the nozzle angle kink 28 and provides a reliable breakdown in the zone between the annular regions 30 and 32.
  • the angle kink 28 formed on the interior 36 of the nozzle has a minimum radius of curvature as compared to the radius of curvature of the adjoining portions of the surface so as to create a protrusion which produces the electric field enhancement discussed above.
  • the angle kink 34 on the electrode should have the smallest radius in the immediate region adjoining the point of closest spacing between the electrode and the nozzle at the gap 42.
  • the breakdown voltage can be reduced between the annular regions 32 and 30 with respect to the remainder of the electrode-nozzle chamber 25.
  • an angle kink 34 on the electrode and an angle kink 28 on the nozzle that are each characterized by a minimum radius of curvature, then there will be a strong electric field enhancement that the electrode angle kink 34 which tends to concentrate the electric field strength between the annular regions 30 and 32.
  • This enhanced field strength in turn both assures that breakdown will occur between the zones across the gap 42 and that the breakdown potential will be reduced as compared to the potential required if the nozzle 12 had a simple conical configuration as depicted in Fig. 3.
  • Fig. 4 illustrates alternative embodiment of the present invention where the nozzle has a generally cylindrical interior configuration formed by a cylindrical side wall 12a' and a lower end wall 12b' that includes the exit port 44' (like parts being identified with the same reference number in the different embodiments).
  • the nozzle 12' is spaced symmetrically from the electrode 14' .
  • the nozzle end wall 12b' is spaced closer to the opposite surface of the electrode than the side wall 12a' .
  • An angle kink 28' is formed on the inner surface 26' of the nozzle by the intersection of the generally planar inner surface portion 26a' defining the end wall 12b' and a conical surface 26b' extending between the exit port 44 and the inner surface portion 26a' .
  • the conical surface 26b' is typically inclined at about 10° from the plane of the surface portion 26b' .
  • the angle kink 28" is located at a point of closest spacing from the electrode 14' , and preferably directly opposite an angle kink 34' formed on the lower end of the electrode. As shown, the angle kink 34' is the circumferentially extending solid angle defined by the intersection of a conical surface 36' and an end surface 38' .
  • the electrode 14' has a cylindrical electron emitting insert 48 at the center of its lower end face 38', directly opposite the exit port 4 .
  • the angle kinks 28' and 32' are centered in narrow annular regions 30', 32' which define a zone in which the plasma arc discharge will preferentially occur.
  • the gap 42' between the angle kinks 28' and 34' is a point of closest approach.
  • the nozzle construction of the present invention when used with a 200 ampere plasma torch of the type sold by Hypertherm, Inc. under the trade designation MAX 200, reduced the maximum breakdown potential by as much as 10% and reduced electrode wear by as much as 30%. Comparable reductions have been obtained with other torches under standard operating conditions. Moreover, the pilot arc discharge has been found to occur preferentially and reliably within a zone defined at its ends by the annular regions 30 and 32.
  • angle kink on the nozzle has been described as formed by the intersection of combinations of conical and planar surfaces, it may be formed with a rounded cross-section, a rounded cross-section with a circumferentially extending ridge at its "peak", or a variety of other configurations which produce a protrusion with a minimum radius of curvature, in cross section, located at a point of closest spacing to the opposed cathode, or anode, and with this closest spacing being a localized point of minimum spacing.
  • angle kinks have been described and illustrated for the nozzle and electrode as being circumferentially extending, they could be formed to extend in angular displacement over less than 360° about the axis 40.

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

Une torche à arc de plasma met en ÷uvre une électrode (14) et un ajutage (12) séparés par un espacement, symétriquement autour d'un axe longitudinal (40) commun, à une extrémité de la torche (10) adjacente à une pièce. La surface intérieure (26) de l'ajutage (12) présente une partie saillante (28) annulaire dirigée vers l'intérieur et située en regard de l'électrode (14) et en un point d'espacement très étroit entre l'électrode (14) et l'ajutage (12). La partie saillante, ou 'coque d'angle' (28), est caractérisée par un rayon de courbure minimal comparé aux rayons de courbure des parties adjacentes de l'ajutage (12) en regard de ladite électrode (14). La surface intérieure (26) est adjacente à un passage de sortie central (44) de l'ajutage (12) et la coque d'angle (28) est espacée de l'intersection de l'orifice de sortie (44) et de l'ajutage intérieur (26). Dans la forme d'exécution préférée, la surface d'ajutage intérieure (26) est formée par deux surfaces coniques ayant chacune des inclinaisons différentes par rapport à l'axe longitudinal (40) de manière à former, au niveau de leur plan d'intersection, la coque d'angle (28) s'étendant circonférentiellement.
PCT/US1990/004112 1989-10-20 1990-07-20 Ajutage perfectionne pour torche a arc de plasma WO1991005629A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE69021736T DE69021736T2 (de) 1989-10-20 1990-07-20 Verbesserte düse für plasmalichtbogenbrenner.
EP90911719A EP0496733B1 (fr) 1989-10-20 1990-07-20 Ajutage perfectionne pour torche a arc de plasma

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US42467589A 1989-10-20 1989-10-20
US424,675 1989-10-20

Publications (1)

Publication Number Publication Date
WO1991005629A1 true WO1991005629A1 (fr) 1991-05-02

Family

ID=23683469

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1990/004112 WO1991005629A1 (fr) 1989-10-20 1990-07-20 Ajutage perfectionne pour torche a arc de plasma

Country Status (6)

Country Link
EP (1) EP0496733B1 (fr)
JP (1) JPH05502189A (fr)
AU (1) AU628617B2 (fr)
CA (1) CA2065431C (fr)
DE (1) DE69021736T2 (fr)
WO (1) WO1991005629A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0639041A1 (fr) * 1993-08-11 1995-02-15 Miller Thermal, Inc. Pistolet de pulvérisation par plasma d'arc et anode correspondante
CH687354A5 (it) * 1992-06-18 1996-11-15 Rodasky Etablissement Elettrodo per torcia per taglio al plasma e torcia atta ad utilizzare detto elettrodo.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914573A (en) * 1971-05-17 1975-10-21 Geotel Inc Coating heat softened particles by projection in a plasma stream of Mach 1 to Mach 3 velocity
US4275287A (en) * 1978-09-28 1981-06-23 Daidoto Kushuko Kabushikaisha Plasma torch and a method of producing a plasma
US4506136A (en) * 1982-10-12 1985-03-19 Metco, Inc. Plasma spray gun having a gas vortex producing nozzle

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914573A (en) * 1971-05-17 1975-10-21 Geotel Inc Coating heat softened particles by projection in a plasma stream of Mach 1 to Mach 3 velocity
US4275287A (en) * 1978-09-28 1981-06-23 Daidoto Kushuko Kabushikaisha Plasma torch and a method of producing a plasma
US4506136A (en) * 1982-10-12 1985-03-19 Metco, Inc. Plasma spray gun having a gas vortex producing nozzle

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH687354A5 (it) * 1992-06-18 1996-11-15 Rodasky Etablissement Elettrodo per torcia per taglio al plasma e torcia atta ad utilizzare detto elettrodo.
EP0639041A1 (fr) * 1993-08-11 1995-02-15 Miller Thermal, Inc. Pistolet de pulvérisation par plasma d'arc et anode correspondante

Also Published As

Publication number Publication date
DE69021736T2 (de) 1996-04-25
EP0496733A1 (fr) 1992-08-05
AU6058290A (en) 1991-05-16
EP0496733A4 (fr) 1992-06-03
CA2065431C (fr) 1995-12-05
EP0496733B1 (fr) 1995-08-16
CA2065431A1 (fr) 1991-04-21
DE69021736D1 (de) 1995-09-21
AU628617B2 (en) 1992-09-17
JPH05502189A (ja) 1993-04-22

Similar Documents

Publication Publication Date Title
US5164568A (en) Nozzle for a plasma arc torch having an angled inner surface to facilitate and control arc ignition
US4782210A (en) Ridged electrode
KR100203836B1 (ko) 개선된 노즐조립체를 갖는 플라스마 아크 토오치 및 노즐조립체
US4452686A (en) Arc plasma generator and a plasma arc apparatus for treating the surfaces of work-pieces, incorporating the same arc plasma generator
EP0727922B1 (fr) Torche a plasma
US4954688A (en) Plasma arc cutting torch having extended lower nozzle member
US4506136A (en) Plasma spray gun having a gas vortex producing nozzle
US6903301B2 (en) Contact start plasma arc torch and method of initiating a pilot arc
US5747767A (en) Extended water-injection nozzle assembly with improved centering
US7145099B2 (en) Tip gas distributor
EP0481958A1 (fr) Protège-buse pour une torche plasma à arc
US20020117482A1 (en) Dual mode plasma arc torch
US7126080B1 (en) Plasma gas distributor with integral metering and flow passageways
US4580031A (en) Plasma burner and method of operation
CA2065431C (fr) Buse pour soudage plasma
US5264679A (en) Alternating current welding apparatus
US6137079A (en) TIG welding torch permitting improving striking the welding arc
US6933461B2 (en) Tips and contact members having ridges for use in a contact start plasma arc torch
KR102423771B1 (ko) 하이브리드 플라즈마 장치
US6002096A (en) Plasma torch with a single electrode producing a transferred arc
SU791098A1 (ru) Плазменный источник электронов
JP2601913B2 (ja) ガスレーザ管
GB2173943A (en) Improvements in and relating to cathodes
JPS61233947A (ja) 静電レンズ

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU CA JP

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB IT LU NL SE

WWE Wipo information: entry into national phase

Ref document number: 2065431

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: 1990911719

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1990911719

Country of ref document: EP

WWG Wipo information: grant in national office

Ref document number: 1990911719

Country of ref document: EP