Connect public, paid and private patent data with Google Patents Public Datasets

Plasma jet generator

Download PDF

Info

Publication number
US3770935A
US3770935A US3770935DA US3770935A US 3770935 A US3770935 A US 3770935A US 3770935D A US3770935D A US 3770935DA US 3770935 A US3770935 A US 3770935A
Authority
US
Grant status
Grant
Patent type
Prior art keywords
plasma
jet
gas
guide
fig
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.)
Expired - Lifetime
Application number
Inventor
H Tateno
T Ichimiya
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.)
Riken Corp
Original Assignee
Riken Corp
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
Grant date

Links

Images

Classifications

    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05HPLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00Generating plasma; Handling plasma
    • H05H1/24Generating plasma
    • H05H1/26Plasma torches
    • H05H1/32Plasma torches using an arc
    • H05H1/44Plasma torches using an arc using more than one torch

Abstract

Disclosed is an improved plasma jet generator comprising at least two plasma jet torches and a guide attachment integrally connected to the torches with a view to fixing the anode foot of a non-transferred type plasma jet. This special structure permits the proper selection of the point of the anode foot of the plasma jet with respect to the cathode spot of the plasma jet, thus realizing a high voltage plasma jet. Also, the new structure prevents the local erosion to the parts of the electrodes on which the anode foot and the cathode spot stand by means of an inactive gas, thus allowing the main arc column to directly heat a high concentrated active gas.

Description

United States Patent 1191 Tateno et al. Nov, 6, 1973 1 PLASMA JET GENERATOR 3,536,885 10/1970 Mitchell 219/121 P 1 1 m 111 11 1 110 1 313133 311331 211112121111 51 91151; lchlmlya Hayama-Machh both of 3,588,594 6/1971 Yamanoto et al. 315 111 Japan 3,403,211 9/1968 Foex 219 121 P x [73] Assignee: Rikagaku Kenlkynsho, Wako-shi Saitama-ken, Japan [22] Filed: Dec. 21, 1971 [21] Appl. No.: 210,350

[] Foreign Application Priority Data Dec. 25, 1970 Japan /118284 Sept. 17, 1971 Japan 46/72338 [52] U.S. Cl 219/121 P, 219/ [51] Int. Cl 323k 9/00 [58] Field of Search 219/121 P, 121 R,

[56] References Cited UNITED STATES PATENTS 3,373,306 3/1968 Karlovitz 219/1211 X 3,476,907 11/1969 Foex et al 219/121 P 3,541,297 11/1970 Sunnen et al 219/121 P Primary Examiner-C. L. Albritton Assistant Examiner-Gale R. Peterson Att0rneyBucknam & Archer Disclosed is an improved plasma jet generator comprising at least two plasma jet torches and a guide attachment integrally connected to the torches with a view to fixing the anode foot of a non-transferred type plasma jet. This special structure permits the proper selection of the point of the anode foot of the plasma jet with respect to the cathode spot of the plasma jet, thus realizing a high voltage plasma jet. Also, the new structure prevents the local erosion to the parts of the electrodes on which the anode foot and the cathode spot stand by means of an inactive gas, thus allowing the main arc column to directly heat a high concentrated active gas.

ABSTRACT 3 Claims, 11 Drawing Figures SHEET 1 BF 5 PATENTEI] NOV 6 I975 PATENTEDNHV si n 3.770.935

SHEET 50F 5 PLASMA JET GENERATOR This invention relates to a plasma jet generator including a plurality of plasma jet torches which are capable of independently functioning as the plasma jet torch of straight polarity.

Thus, the wall of the torch will be free from the damage which would be caused by using the torch wall as the negative electrode if the torch is used in the mode of reverse polarity. The plasma jets ejected from those plasma jet torches will meet one another in the inner space of a guide attachment which are integrally connected with the torches. A main arc can be established in the electrically conductive space by applying a voltage from a main power supply with one electrode of each plasma jet torch used as the positive or negative electrode, and the gas supplied will be heated by the main arc and then properly directed by the guide attachment.

A plasma jet generator (hereinafter abbreviated to P.J.G.) has been widely used in cutting, welding, coating and other operations. The basic structure of P.J.G. (see US. Pat. No. 2,806,124) was originally developed by Union Carbide Corporation, and numerous im provements have been proposed. In these P.J.G.s, the factors to determine the electric characteristics thereof are as, for instance, follows: gas flow rate, gas compositions, size of caliber, distance between the electrodes, and electric current values. It should be noted that the arc voltage also depends on these factors.

The efficiency of heating gas is usually given by the following equation:

The efficiency of heating gas (1;)

Arc Electric Torch Voltago(V) X Currontfl) Consumption (Lt)- Arc Voltage (V) lfllectric Current (I) provided that: Torch Consumption(L,) K X Electric Current(l) Thermal Conduction to Casing Wall(L,,,) z

where K is a constant.

By substituting Equation (2) for the corresponding term of Equation (1 the following equation can be obtained:

The last term is negligible for its smallness, and therefore it is apparent the efficiency will increase with the arc voltage.

A conventional method of increasing the arc voltage is to increase the eddy component of the gas stream in passing through the torch.

Another means to increase the arc voltage is to provide recessed portions electrically isolated both from the anode and the cathode in the flow path of gas. However, relaying on these means, the arc voltage for given values of gas flow rate and electric current cannot be raised beyond a certain critical value without accompanying adverse effects such as double arcing, damage of the throat aperture, and deviation or unstability of the arc column. P.J.G.s heretofore proposed still have defects such as complicatedness in structure, difficulty in operation and narrow range for varying electric current, gas flow rate and other factors.

An object of this invention is to provide an improved P.J.G. which is characteristic of the high are voltage and hence the highly improved efficiency of heating gas and little or no electrode consumption.

Another object of this invention is to provide a new high-voltage lP..I.G. in which an active gas of high density can be heated directly by the arc column. This direct heating of concentrated active gas by means of the arc column was deemed as impossible in the prior art.

This invention will be better understood from the following description which is to be made with reference to the accompanying drawings:

FIG. I shows an embodiment of the P.J.G. according to this invention in section and an associated electric circuit;

FIG. 2 is a similar view to FIG. I, but shows a different embodiment suitable for a concentrated active gas and an associated electric circuit;

FIGS. 3 8 show partly in section, different guide attachments suitable for use in the P.J.G. given in FIG.

FIG. 9 is a similar view to FIG. 2, except for the structure of the guide attachment;

FIG. 10 shows in section an embodiment of this invention having two positive plasma jet torches and one negative plasma jet torch, and an associated circuit; and

FIG. II shows in cross-section, different shapes of the white-bright portion of the plasma flame at the out let.

Referring to FIG. I there is shown a primary PIG. according to this invention which consists of a positive plasma jet torch A, a negative plasma jet torch B and a guide attachment C. The positive plasma jet torch A has a cathode rod I and at least two bushings 2, 3 mounted concentric with the cathode rod. The second bushing 3 has an arc throttle aperture I. A gas such as Argon, Helium and other inactive gases is supplied in the form of stream 7 and 8 from the inlets 5 and 6 to the annular space formed between the cathode and the first bushing 2 and the one between the first bushing 2 and the second bushing 3 respectively. The negative plasma jet torch B has a cathode rod 9 and a bushing II positioned concentric with the cathode. The bushing II has an arc throttle aperture It). An inactive gas I3 is supplied from the inlet I2 to the annular space formed between the cathode 9 and the bushing II.

The guide attachment C has two inlets I5 and I6 and one outlet I7. These inlets are so positioned that when the guide attachment is fixed to the positive and nega' tive jet torches, these inlets function to direct the gas streams from the torches to the intersection of the center axis of these torches, whereas the outlet is so positioned that it functions to allow the resultant gas stream to flow from the intersection to the exterior.

It should be noted that the guide attachment is fixed to at least one bushing (the bushing 3 of the positive plasma jet torch in FIG. I) via an insulator Id of a dielectric material, and that a gas 2b is supplied from the inlet I9 to the annular space formed by the insulator I8 at the joint part. The cathode holders 5th, 511 and the bushings 2, 3, II and the guide attachment C are watercooled by a proper means (not shown), and are integrated via insulators 52 of, for instance, Bakelite in a complete air-tight manner.

An auxiliary power supply 21 includes a highfrequency oscillator for arc-establishment. The negative terminal of the power supply 21 is connected to the cathode 1 of the positive jet torch A via an electric switch 22 whereas the positive terminal is connected to the bushing 2 of the torch A.

Likewise, the negative terminal of the main power supply 23 containing a high-frequency oscillator for arc-establishment is connected to the cathode 9 of the negative plasma jet torch B, and the positive terminal of the main power supply is connected to the bushing 2 of the torch A. The positive terminals of the power supplies 21, 23 are connected to the bushing 11 via a switch 24. The P.J.G. thus connected to the associated circuit will be operated as follows:

1. Gas 7, 8 is supplied to the positive plasma jet torch A, and then the high-frequency oscillator of the auxiliary power supply 21 is put into operation by closing the switch 22. As a result an auxiliary arc 25 is established and finally a plasma jet flame is formed and extends from the arcthrottle aperture 4 into the guide attachment C.

2. Gas 13 is supplied, and then the high-frequency oscillator of the main power supply 23 is brought into operation by closing the switch 24. As a result an are 26 is established, and then a plasma jet flame is formed and extends from the arc-throttle aperture into the guide attachment C.

3. After the plasma jet flames of straight polarity are thus established and meets one another at the intersection 14, the switch 24 is opened. Then a hairpin shaped main arc is formed, and the plasma jet flame 28 extends from the outlet 17 of the guide attachment C to the exterior.

The supply of the gas stream 20 from the inlet 19 of the guide attachment C may be begun before or after operation 3 above. The hairpin-shaped arc happens to open wide, and as a result the curved leg of the arc approaches one side of the inlet of the attachment to excessively heat the wall of the inlet 15. Partly because of this and partly because of the injection of ions into the inlet wall it is most likely that a cathode spot is formed on the inlet wall. This is the cause for the formation of a double arc. The supply of the gas stream is useful to first, prevent the hairpin are from opening wide and second, prevent ions from invading the inlet wall, thus finally eliminating the possibility of establishing a double arc.

The high-voltage P.J.G. thus operated is capable of establishing a stable arc whose arc-voltage is at least two times as high as the arc-voltage of the conventional P..I.G. for given electric current and gas flow rate.

EXAMPLE l The particulars of the apparatus according to the embodiment shown in FIG. 1 are:

Diameter of the throttle aperture 4 of the bushing 3 Diameter of the inlet 15 of the guide attachment Diameter of the inlet 16 of the guide attachment Diameter of the passage 30 of the guide attachment Distance from the intersection 14 to the end of the bushing 2 18 mm Distance from the intersection 14 to the tip of the cathode 9 27 mm Flow rate of gas 7 (Argon) 0.2 l/rnin.

Flow rate of gas 8 (Argon) 0.4 l/min.

Flow rate of gas 13 (Argon) 3.0 l/min.

Flow rate of gas 20 (Argon) 0.2 l/min.

Arc current 20 A A possible longest plasma jet flame was formed and the arc voltage was as high as 76 volts. (The are voltage in the conventional plasma jet torch is 30 volts or less for the same current and flow rate.)

Referring to FIG. 2, there is shown a P.J.G. according to this invention which is capable of heating a concentrated percent or more) gas chemically active to the material of the electrode such as oxygen or air directly by means of an arc column.

In spite of ever increasing demand for this capability of direct heating an active gas in the fields of chemical reactions, coating, cutting and other appliances since the appearance of the P.J.G., it could not be attained before the completion of this invention.

In the apparatus of FIG. 2 the positive plasma jet torch A is similar to that of the apparatus of FIG. 1. The negative plasma jet torch B has an extra bushing 34 with a throttle aperture 34 and extra inlets 35, 36 for gas 37, 38, compared with the negative plasma jet torch B in FIG. 1. The guide attachment C is fixed to the bushing 34 via an electric insulator 18. Complying with this modification the positive terminal of the main power supply 23 is connected to the bushings 11 and 34 and the guide attachment C.

This apparatus can be operated as I. Argon is supplied in the form of gas stream 7, and then the switch 22 is closed to start the operation of the high-frequency oscillator of the auxiliary power supply 21 with a result of a establishing an auxiliary arc 25. Then, the plasma jet flame is ejected from the throttle aperture 4, and it extends into the main passage 30. Additionally, argon is supplied in the form of the gas streams 8 and 20.

2. Argon is supplied in the form of the gas streams 13, 37 and 38, and then the switches 24, 24' and 24" are closed for the main power supply 23 to apply a dc. voltage and a high-frequency voltage to the torch B and the guide attachment C with a result of establishing the first non-transferred are 26. Then, the switch 24 is opened, transforming the arc column into the second non-transferred are 26'. Next, the switch 24' is opened, thus again transforming the arc column into the third nontransferred are 26'. Then, the supply of gas 13 to the cathode is made to cease, and the switch 24" is opened with a result of establishing the main arc column 27.

3. The switch 22 is opened to extinguish the are 25,

and at the same time the supply of gas 7 to the cathode is made to cease. Finally, the gas streams 2th and 38 are switched from argon to air or oxygen. Thus, a highly concentrated active gas plasma jet can be obtained.

This operation can be reduced to a full automatic on-of operation by using a piping system which includes pre-adjusted needle valves and electromagnetic valves.

EXAMPLE 2 The particulars of the apparatus shown in FIG. 2 are: Diameter of the inlet 15 or 16 of the guide attachment C 3 mm Diameter of the gas channel of the guide attachment mm 1 Diameter of throttle aperture 34' of the bushing 34 2 mm Distance from the intersection M to the end surface of the bushing 2 18 mm Distance from the intersection M of the tip of the cathode 9 34 mm Flow rate of the gas stream 3 (Argon) 0.3 l/min. Flow rate of the gas stream 20 (Oxygen) 0.2 l/min. Flow rate of the gas stream 37 (Argon) 0.3 l/min.

Flow rate of the gas stream 3% (Oxygen) 5 Are current 20 A A plasma flame of 90 percent oxygen concentration was obtained, and the are voltage was as high as 115 volts. The substitution of air for oxygen caused the arc voltage to rise up to 135 volts.

A mixture of a higher active gas content can be used by enhancing the cooling capability to the bushings and by increasing the arc current.

With a view to improving the directional stability of the plasma jet flame and at the same time with a view to increasing the efficiency of heating gas the inventors carried out experiments on a variety of guide attachments as follows:

The guide attachment shown in FIG. 3 is the same as the corresponding part of the apparatus shown in FIG. 1 except for a notched portion a at the downstream side thus making the terminal end of the outlet 17 fairly close to the hairpin arc column. In this modification the plasma jet flame 2b deviated apart from the center axis 29 of the outlet I7, and the directionarity varied with the gas flow rate and the value of electric current.

FIG. 4 shows further modification of the guide attachment of FIG. 3 in that the gas channel is enlarged around the intersection M- at the upstream side while still maintaining the cross-section of the outlet equal to that of the outlet of the guide attachment shown in FIG. 11 or 3. In this case the plasma jet flame 23 was positioned on the center axis 29 of the outlet 17.

FIG. 5 shows a guide attachment shown in FIG. ll modified in the same manner as in FIG. 4i. In this modification, likewise, the plasma jet flame 28 was positioned on the center, axis 29 of the outlet I7, and what was better, the length of the white bright portion of the laminated flow of the plasma jet flame was increased approximately 50 percent. This indicates that the ejection of the plasma jet flame was remarkably enhanced. A similar result was obtained with regard to the guide attachment the gas channel of which was modified as indicated by broken line 3ll.

FIG. 6 shows further modification of the guide attachment of FIG. 5 in that the part b indicated by broken line was removed. In this case the laminar stream of the plasma jet flame 2% deviated with respect to the center axis 29 of the outlet 17.

The guide attachments shown in FIGS. 3, 4, 5 and 6 were tested for the same values of gas flow rate and electric current.

The results of these experiments indicate that:

l. The removal of the part a from the end of the attachment given in FIG. l is useful to direct the plasma jet flame along the center axis 29 of the guide channel.

2. The cross-sectional enlargement of the guide channel shown in FIG. d endows the guide attachment with the directionality of the plasma jet flame.

l/min.

3. The enlargement of the guide channel in the guide attachment free of the notched portion a as shown in FIG. 5 is useful to reduce the loss of the plasma jet flame which otherwise would be caused at the part corresponding to the notched portion a in FIG. 3.

4. If the cross-sectional enlargement extends far to the inlet of the guide attachment as shown in FIG. 6, the effect of directing the plasma jet flame on the center line will disappear. From the results of the experiments above mentioned, the inventors reached the conclusion as follows:

The structures of the guide attachments given in FIGS. 4 and 5 are useful to throttle the disturbing fluid flow which results from the two gas streams supplied from the two inlets of the guide attachment so as to allow the resultant flow to align in the center line of the guide attachment.

As seen from FIG. 6, the position of the outlet relative to the arc column is critical, and it is necessary to allow a part of the hairpin" are or at least the sharp bent portion of the hairpin to appear in the throttle aperture for the following reasons:

First, the entrance of a part of the are column into the throttle aperture will cause the rise of the temperature of the gas in the throttle aperture, and hence the increase of the cubic expansion of the gas, finally resulting in the increase of the flow resistance of the throttle, which is useful to improve the directing capability of the throttle. Second, the directing effect realized by the wall of the aperture at the sacrifice of the heat loss as is the case with the device in FIG. ll, can be reduced, and the ejection of the plasma jet flame will be improved because the hairpin" of the arc whose thermal energy is about half the total energy of the arc column, is aligned in the central axis of the throttle aperture for heating the gas.

FIGS. 7 and 3 show other modifications of the guide attachment. The guide attachment of FIG. '7 is specifically designed for the cutting operation. In this example the space 32 which the hairpin" enters is made larger than the outlet 117 of the guide attachment which is for instance as small as 1.0 mm diameter across, because otherwise the hairpin would not enter the throttle aperture.

FIG. b shows a modification of the guide attachment of FIG. d. In this modification a blind hole 33 is made on the wall of the guide channel opposite to the inlet 15 of the guide attachment. Thus, the directness of a laminar flow of plasma jet which is ejected from an aperture I7 of relatively small diameter was substantially improved.

As is apparent from the results of the experiments on the modifications given in FIGS. 3 6., the directness of a plasma jet flame can be improved, and at the same time the efficiency of heating gas can be raised by enlarging the cross-section of the guide channel over the length of the channel beyond the intersection of the two center axes of the positive and negative plasma jet torch towards the outlet.

FIG. 9 shows a P.J.G. which is equivalent to the embodiment of FIG. 2 modified by substituting the guide attachment of FIG. 4 or 5 for the corresponding member of the apparatus of FIG. 2. This modification was compared with the apparatus of FIG. 2. as follows:

EXAMPLE 3 Operating condition:

Gas stream 8 Argon 0.3 l/min.

Gas stream 37 Argon 0.3 l/min.

Gas stream 7 none Gas stream 13 none Gas stream 38 Oxygen 4 l/min.

Gas stream 20 Oxygen 1 l/min.

Arc voltage 95 V Arc current 50 A P.J.G. of FIG. 2

Diameters d d of the inlets 15, 16 d d 3.0 mm

Diameter d of the outlet 17 d 5.0 mm

Distance I from the intersection 14 to the outlet 17 -l 8.5 mm

The plasma jet flame extended 25 to 30 cm, and it deviated about 2 apart from the center axis 29.

P.J.G. of FIG. 9

Diameters (l 11 of the inlets I5, I6 d d =3.0 mm.

Diameter d, of the outlet d 5.0 mm

Diameter d of the guide channel d 7.0 mm

Distance 1 from the intersection 14 I4 to the outlet I7 1 4.5 mm, I 4.0 mm

The plasma jet flame extended 35 to 50 cm on the central axis 29.

The throttle part was modified into the two step form as shown in FIG. 7.

The following are voltages were realized for different diameters d and d of the inlet 16 and the outlet 17, and the ejection of the plasma jet flame suitable for the cutting operation was substantially improved.

Pressure in the Guide d, d, Are Voltage Attachment (Gauge din. dia. Pressure) 3.0 mm 3.0 mm 95 V 20mm 15 mm llOV 0.1 kg/em 2 mm l 0 mm I20 V 1.0 kg/cm EXAMPLE 4 Operating Condition Gas stream 38 Oxygen l2 l/min. Gas stream 20 Oxygen 3 l/min (The flow rates of the other gas streams were equal to those in Example 3.) Are voltage 130 V Arc current 50 A P.J.G. of FIG. 2

The dimensions of the apparatus were identical with those of Example 3. The incandescent part of the flame was composed of a disturbed flow about 2 cm. long, and the plasma jet flame deviated about 3 or more apart from the central axis. P.J.G. of FIG. 9

The particular dimensions of the apparatus were identical with those of Example 3. The incandescent part of the flame was composed of a disturbed stream about 3.5 cm long, and the plasma jet flame was directed straight.

The deviation and the length of the plasma jet flame is a direct measure for the efficiency of heating gas for a given condition. In view of this it is apparent that the effect of the special structure of the guide attachment given in FIG. 4 or is remarkable for improving the efficiency of heating gas. Additionally, the capability for varying the flow rate of the gas stream 20 over a wide range facilitates the operation of the apparatus.

As seen from the above, the P.J.G. according to this invention has a single throttle aperture and at least one anode electrode, essentially different from a conventional P.J.G. using the inside wall of the throttle aperture as the anode electrode.

The advantages attributable to the use of a plurality of positive plasma jet torches are:

First, as a matter of course, the anode input power can be equally divided into as many parts as the positive plasma jet torches, thus avoiding the damage of the throttle aperture due to the local concentration of heat as is the case with the conventional P.J.G. Second, the adverse effect by the gas injection from the inlet 15 on the main arc column can be substantially reduced.

FIG. 10 shows a P.J.G. having a negative plasma jet torch and two positive plasma jet torches positioned symmetrical to the negative torch. This apparatus is identical with the apparatus of FIG. 1 except for the guide attachment. A single switch 24 is provided for generating a plasma jet flame in each of the negative torches. Although two auxiliary power supplies 21 are shown in the drawing, a single power supply in place of these devices can be used by properly modifying the relevant electrical connection because the device is not used with regard to the positive plasma jet torches at the same time.

In operation, a main arc is established by the positive plasma jet torch to which the switch 24 is connected (right torch in the drawing), in the same manner as in the apparatus of FIG. 1. With the main are thus established, an auxiliary arc is established by the other positive plasma jet torch (left torch in the drawing), and then a main arc is established therein. After the establishment of the main are at the left side the switch 22 is opened, and then the supply of the gas stream 7 is made to cease. The flow rates of the gas 7 and 8, such as argon are set to a proper value, for instance 0.2 l/min. Thus, the main are 27 is finally established.

In a particular example of the apparatus the total electric current was 40 A and the are voltage was 73 V.

FIG. Ill shows the shapes of the cross-sections of the incandescent cores of different plasma jet flames which are ejected from the main channel 30 when the gas is supplied from either of the right and left positive plasma jet torches at an equal pressure balancing at the center of the main channel. In this drawing the outer circle 39 is the wall of the main channel of the guide attachment, and the direction of the gas supplied by the positive plasma jet torch is indicated by the arrow. The shaded part 40 is the cross-section of the incandescent part or core of the plasma jet flame in the outlet 17.

FIG. ll-I pertaining the use of a single positive plasma jet torch shows the off-center position of the incandescent core, the cross-section of which is of an ellipse. This phenomenon is observed in the plasma jet flame in a conventional torch.

FIG. Ill-II pertaining to the use of two positive plasma jet torches shows the on-center position of the incandescent core 40, the cross-section of which is of an ellipse.

FIG. lI-III pertaining to the angular arrangement of three positive plasma jet torches apart shows the on-center position of the incandescent core 40, the cross-section of which is almost circular.

F IG. ll-IV pertaining to the angular arrangement of four positive plasma jet torches 90 apart shows the on-center position of the incandescent core, the cross-section of which approaches a circle.

The positioning of the incandescent core on the exact center of the throttle aperture as shown in FIGS. 11-11, Ill and IV means the aligning of the plasma jet flame in the central axis of the main channel, thus decreasing the thermal loss which would be caused if the plasma jet flame approaches the channel wall apart from the center. The centering of the plasma jet flame by means of a plurality of positive plasma jet torches is useful to improve the efficiency of the apparatus.

For the sake of simplicity this invention has been heretoabove described with reference to the nontransferred type straight polarity P. l.G., but it should be noted that the reverse polarity P.J.G. according to this invention is equally useful. It is commonly admitted that the use of oxygen or air in the transferred type P..l.G. will increase the cutting speed for steel or alu minium sheets. However, in order to avoid the damage to the electrode of a conventional P.J.G. (more specifically in order to assure the life of the apparatus as long as the apparatus using argon), it is necessary to use an inactive gas in the mode of non-transferred operation and then introduce oxygen or air as a substitute for the inactive gas after the transition of the arc to the workpiece. This operation is too inconvenient, and it makes the apparatus actually useless. This defect is overcome by, according to this invention, generating first nontransferred plasma jet with the aid of an auxiliary power supply and second, a transferred plasma jet between the cathode rod and the workpiece with the aid of the main power supply.

This invention has been heretoabove described as using plasma jet of straight polarity, but it is apparent to the skilled in the art that a P.J.G. according to this invention can equally use plasma jet of reverse polarity. in other words, a P.J.G. according to this invention will not be deteriorated, which type of plasma jet may be used. The embodiments herein disclosed have the axis of the positive plasma jet torch and the axis of the negative plasma jet torch transverse therewith. However, in cutting a workpiece of a dielectric material, such as concrete in the mode of non-transferred operation or in cutting a workpiece of a conductive material, such as aluminium, iron and other metals in the mode of transferred operation, two plasma jet torches were angularly arranged thus first allowing the hairpin" arc to approach the outlet with a result of increasing the thermal energy to the workpiece and second, making the outlet accessible to the workpiece because the plasma jet units causes little or no hindrance against the workpiece. As a matter of course, the angle at which the two plasma jet units are arranged can be arbitrarily determined to meet the requirements.

The P..l.G. has been widely used in numerous industrial fields since it appeared in the world, and this invention enlarges'the domain of appliance to the possible extremity from the points of economical and technical views.

What is claimed is:

l. A plasma jet generator comprising a plurality of plasma jet torches, a hollow guide attached to said torches, said hollow guide having an outlet and a plurality of inlets, said inlets being disposed to receive and direct the gas streams from respective torches to intersect at a given location within the guide to form a combined plasma jet exiting the guide through said outlet, said inlets and outlets being the only openings in said hollow guide, one of said torches including a cathode rod and at least two bushings which define a gas flow space, and said hollow guide being electrically insulated from at least one of said torches by a body of dielectric material.

2. A plasma jet generator according to claim l including two plasma jet torches disposed to produce gas streams that are oriented generally perpendicular to each other.

3. A plasma jet generator according to claim l. including three plasma jet torches disposed to produce gas streams, two of which gas streams are oriented generally symmetrical with respect to the third gas stream. l: ll= 4F t =l=

Claims (3)

1. A plasma jet generator comprising a plurality of plasma jet torches, a hollow guide attached to said torches, said hollow guide having an outlet and a plurality of inlets, said inlets being disposed to receive and direct the gas streams from respective torches to intersect at a given location within the guide to form a combined plasma jet exiting the guide through said outlet, said inlets and outlets being the only openings in said hollow guide, one of said torches including a cathode rod and at least two bushings which define a gas flow space, and said hollow guide being electrically insulated from at least one of said torches by a body of dielectric material.
2. A plasma jet generator according to claim 1 including two plasma jet torches disposed to produce gas streamS that are oriented generally perpendicular to each other.
3. A plasma jet generator according to claim 1 including three plasma jet torches disposed to produce gas streams, two of which gas streams are oriented generally symmetrical with respect to the third gas stream.
US3770935A 1970-12-25 1971-12-21 Plasma jet generator Expired - Lifetime US3770935A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP11828470A JPS4932691B1 (en) 1970-12-25 1970-12-25
JP7233871A JPS5210809B2 (en) 1971-09-17 1971-09-17

Publications (1)

Publication Number Publication Date
US3770935A true US3770935A (en) 1973-11-06

Family

ID=26413474

Family Applications (1)

Application Number Title Priority Date Filing Date
US3770935A Expired - Lifetime US3770935A (en) 1970-12-25 1971-12-21 Plasma jet generator

Country Status (4)

Country Link
US (1) US3770935A (en)
DE (2) DE7148539U (en)
FR (1) FR2119768A5 (en)
GB (1) GB1346790A (en)

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3949188A (en) * 1973-07-20 1976-04-06 Rikagaku Kenkyusho Method and apparatus for operating an arc-transfer type torch
US4009413A (en) * 1975-02-27 1977-02-22 Spectrametrics, Incorporated Plasma jet device and method of operating same
US4013867A (en) * 1975-08-11 1977-03-22 Westinghouse Electric Corporation Polyphase arc heater system
US4038512A (en) * 1975-08-11 1977-07-26 Westinghouse Electric Corporation Self-stabilizing arc heater
US4220844A (en) * 1973-05-23 1980-09-02 U.S. Philips Corporation Method of and device for plasma MIG welding
US4341941A (en) * 1979-03-01 1982-07-27 Rikagaku Kenkyusho Method of operating a plasma generating apparatus
US4390772A (en) * 1978-09-28 1983-06-28 Susumu Hiratake Plasma torch and a method of producing a plasma
US4540868A (en) * 1982-03-06 1985-09-10 Deutsche Forschungs- Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. Plasma gun that reduces cathode contamination
US4626648A (en) * 1985-07-03 1986-12-02 Browning James A Hybrid non-transferred-arc plasma torch system and method of operating same
US4670290A (en) * 1985-05-13 1987-06-02 Rikagaku Kenkyusho Multiple torch type plasma spray coating method and apparatus therefor
US4896017A (en) * 1988-11-07 1990-01-23 The Carborundum Company Anode for a plasma arc torch
WO1990013392A1 (en) * 1989-05-05 1990-11-15 Tungsram Részvénytársaság Apparatus for machining by the means of a plasma beam a workpiece made of a material of high softening or melting point, especially quartz, glass or a metal
US4982067A (en) * 1988-11-04 1991-01-01 Marantz Daniel Richard Plasma generating apparatus and method
US5008511A (en) * 1990-06-26 1991-04-16 The University Of British Columbia Plasma torch with axial reactant feed
EP0427194A2 (en) * 1989-11-07 1991-05-15 Chichibu Onoda Cement Corporation Multiple torch type plasma generation device and method of generating plasma using the same
US5017752A (en) * 1990-03-02 1991-05-21 Esab Welding Products, Inc. Plasma arc torch starting process having separated generated flows of non-oxidizing and oxidizing gas
US5144110A (en) * 1988-11-04 1992-09-01 Marantz Daniel Richard Plasma spray gun and method of use
US5166494A (en) * 1990-04-24 1992-11-24 Hypertherm, Inc. Process and apparatus for reducing electrode wear in a plasma arc torch
US5170033A (en) * 1990-04-24 1992-12-08 Hypertherm, Inc. Swirl ring and flow control process for a plasma arc torch
US5317126A (en) * 1992-01-14 1994-05-31 Hypertherm, Inc. Nozzle and method of operation for a plasma arc torch
US5396043A (en) * 1988-06-07 1995-03-07 Hypertherm, Inc. Plasma arc cutting process and apparatus using an oxygen-rich gas shield
US5514848A (en) * 1994-10-14 1996-05-07 The University Of British Columbia Plasma torch electrode structure
US5620617A (en) * 1995-10-30 1997-04-15 Hypertherm, Inc. Circuitry and method for maintaining a plasma arc during operation of a plasma arc torch system
US5798493A (en) * 1996-05-14 1998-08-25 Heller, Sr.; Walter R. Fixed welding apparatus and method
US6114649A (en) * 1999-07-13 2000-09-05 Duran Technologies Inc. Anode electrode for plasmatron structure
US6163009A (en) * 1998-10-23 2000-12-19 Innerlogic, Inc. Process for operating a plasma arc torch
US6326583B1 (en) 2000-03-31 2001-12-04 Innerlogic, Inc. Gas control system for a plasma arc torch
US6498317B2 (en) 1998-10-23 2002-12-24 Innerlogic, Inc. Process for operating a plasma arc torch
US6677551B2 (en) 1998-10-23 2004-01-13 Innerlogic, Inc. Process for operating a plasma arc torch
US20100078408A1 (en) * 2008-09-30 2010-04-01 Hypertherm, Inc. Nozzle with exposed vent passage

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4352044A (en) * 1981-01-05 1982-09-28 Zhukov Mikhail F Plasma generator
RU2115269C1 (en) * 1991-02-20 1998-07-10 Жан Капашевич Кульжанов Method of production of arc discharge in plasma generator and device for its realization
DE102007010996A1 (en) * 2007-03-05 2008-09-11 Arcoron Gmbh plasma nozzle

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373306A (en) * 1964-10-27 1968-03-12 Northern Natural Gas Co Method and apparatus for the control of ionization in a distributed electrical discharge
US3403211A (en) * 1965-03-31 1968-09-24 Centre Nat Rech Scient Methods and devices for heating substances
US3476907A (en) * 1966-01-07 1969-11-04 Centre Nat Rech Scient Process for obtaining a permanent flow of plasma
US3536885A (en) * 1965-10-25 1970-10-27 Ass Elect Ind Plasma torch assemblies
US3541297A (en) * 1968-10-07 1970-11-17 Soudure Autogene Elect Heating a reactive fluid to high temperature
US3588594A (en) * 1968-01-19 1971-06-28 Hitachi Ltd Device for bending a plasma flame
US3601578A (en) * 1969-07-01 1971-08-24 Siemens Ag High-pressure plasma burner
US3644782A (en) * 1969-12-24 1972-02-22 Sheet Korman Associates Inc Method of energy transfer utilizing a fluid convection cathode plasma jet

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3373306A (en) * 1964-10-27 1968-03-12 Northern Natural Gas Co Method and apparatus for the control of ionization in a distributed electrical discharge
US3403211A (en) * 1965-03-31 1968-09-24 Centre Nat Rech Scient Methods and devices for heating substances
US3536885A (en) * 1965-10-25 1970-10-27 Ass Elect Ind Plasma torch assemblies
US3476907A (en) * 1966-01-07 1969-11-04 Centre Nat Rech Scient Process for obtaining a permanent flow of plasma
US3588594A (en) * 1968-01-19 1971-06-28 Hitachi Ltd Device for bending a plasma flame
US3541297A (en) * 1968-10-07 1970-11-17 Soudure Autogene Elect Heating a reactive fluid to high temperature
US3601578A (en) * 1969-07-01 1971-08-24 Siemens Ag High-pressure plasma burner
US3644782A (en) * 1969-12-24 1972-02-22 Sheet Korman Associates Inc Method of energy transfer utilizing a fluid convection cathode plasma jet

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4220844A (en) * 1973-05-23 1980-09-02 U.S. Philips Corporation Method of and device for plasma MIG welding
US3949188A (en) * 1973-07-20 1976-04-06 Rikagaku Kenkyusho Method and apparatus for operating an arc-transfer type torch
US4009413A (en) * 1975-02-27 1977-02-22 Spectrametrics, Incorporated Plasma jet device and method of operating same
US4013867A (en) * 1975-08-11 1977-03-22 Westinghouse Electric Corporation Polyphase arc heater system
US4038512A (en) * 1975-08-11 1977-07-26 Westinghouse Electric Corporation Self-stabilizing arc heater
US4390772A (en) * 1978-09-28 1983-06-28 Susumu Hiratake Plasma torch and a method of producing a plasma
US4341941A (en) * 1979-03-01 1982-07-27 Rikagaku Kenkyusho Method of operating a plasma generating apparatus
US4439662A (en) * 1979-03-01 1984-03-27 Rikagaku Kenkyusho Method of operating a plasma generating apparatus
US4540868A (en) * 1982-03-06 1985-09-10 Deutsche Forschungs- Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. Plasma gun that reduces cathode contamination
US4670290A (en) * 1985-05-13 1987-06-02 Rikagaku Kenkyusho Multiple torch type plasma spray coating method and apparatus therefor
US4626648A (en) * 1985-07-03 1986-12-02 Browning James A Hybrid non-transferred-arc plasma torch system and method of operating same
US5591357A (en) * 1988-06-07 1997-01-07 Hypertherm, Inc. Plasma arc cutting process and apparatus using an oxygen-rich gas shield
US5396043A (en) * 1988-06-07 1995-03-07 Hypertherm, Inc. Plasma arc cutting process and apparatus using an oxygen-rich gas shield
US5144110A (en) * 1988-11-04 1992-09-01 Marantz Daniel Richard Plasma spray gun and method of use
US4982067A (en) * 1988-11-04 1991-01-01 Marantz Daniel Richard Plasma generating apparatus and method
US4896017A (en) * 1988-11-07 1990-01-23 The Carborundum Company Anode for a plasma arc torch
WO1990013392A1 (en) * 1989-05-05 1990-11-15 Tungsram Részvénytársaság Apparatus for machining by the means of a plasma beam a workpiece made of a material of high softening or melting point, especially quartz, glass or a metal
EP0427194A2 (en) * 1989-11-07 1991-05-15 Chichibu Onoda Cement Corporation Multiple torch type plasma generation device and method of generating plasma using the same
US5243169A (en) * 1989-11-07 1993-09-07 Onoda Cement Co., Ltd. Multiple torch type plasma generation device and method of generating plasma using the same
EP0427194A3 (en) * 1989-11-07 1991-12-11 Onoda Cement Company, Ltd. Multiple torch type plasma generation device and method of generating plasma using the same
EP0444344A3 (en) * 1990-03-02 1992-01-02 Esab Welding Products, Inc. Plasma arc starting process
EP0444344A2 (en) * 1990-03-02 1991-09-04 ESAB Welding Products, Inc. Plasma arc starting process
US5017752A (en) * 1990-03-02 1991-05-21 Esab Welding Products, Inc. Plasma arc torch starting process having separated generated flows of non-oxidizing and oxidizing gas
US5166494A (en) * 1990-04-24 1992-11-24 Hypertherm, Inc. Process and apparatus for reducing electrode wear in a plasma arc torch
US5170033A (en) * 1990-04-24 1992-12-08 Hypertherm, Inc. Swirl ring and flow control process for a plasma arc torch
US5008511A (en) * 1990-06-26 1991-04-16 The University Of British Columbia Plasma torch with axial reactant feed
US5317126A (en) * 1992-01-14 1994-05-31 Hypertherm, Inc. Nozzle and method of operation for a plasma arc torch
US5514848A (en) * 1994-10-14 1996-05-07 The University Of British Columbia Plasma torch electrode structure
US5620617A (en) * 1995-10-30 1997-04-15 Hypertherm, Inc. Circuitry and method for maintaining a plasma arc during operation of a plasma arc torch system
US5798493A (en) * 1996-05-14 1998-08-25 Heller, Sr.; Walter R. Fixed welding apparatus and method
US6163009A (en) * 1998-10-23 2000-12-19 Innerlogic, Inc. Process for operating a plasma arc torch
US6498317B2 (en) 1998-10-23 2002-12-24 Innerlogic, Inc. Process for operating a plasma arc torch
US6677551B2 (en) 1998-10-23 2004-01-13 Innerlogic, Inc. Process for operating a plasma arc torch
US6114649A (en) * 1999-07-13 2000-09-05 Duran Technologies Inc. Anode electrode for plasmatron structure
US6326583B1 (en) 2000-03-31 2001-12-04 Innerlogic, Inc. Gas control system for a plasma arc torch
US20100078408A1 (en) * 2008-09-30 2010-04-01 Hypertherm, Inc. Nozzle with exposed vent passage
US8338740B2 (en) 2008-09-30 2012-12-25 Hypertherm, Inc. Nozzle with exposed vent passage

Also Published As

Publication number Publication date Type
DE2164270C3 (en) 1974-12-05 grant
DE2164270A1 (en) 1972-07-13 application
DE2164270B2 (en) 1974-05-09 application
GB1346790A (en) 1974-02-13 application
DE7148539U (en) 1972-04-27 grant
FR2119768A5 (en) 1972-08-04 application

Similar Documents

Publication Publication Date Title
US3450926A (en) Plasma torch
US3248513A (en) Equipment for forming high temperature plasmas
US3324334A (en) Induction plasma torch with means for recirculating the plasma
US3194941A (en) High voltage arc plasma generator
US3294953A (en) Plasma torch electrode and assembly
US4982067A (en) Plasma generating apparatus and method
US4916273A (en) High-velocity controlled-temperature plasma spray method
US4777343A (en) Plasma arc apparatus
US5514848A (en) Plasma torch electrode structure
US5147998A (en) High enthalpy plasma torch
US4841114A (en) High-velocity controlled-temperature plasma spray method and apparatus
US3832513A (en) Starting and stabilizing apparatus for a gas-tungsten arc welding system
US3731047A (en) Plasma heating torch
US5760363A (en) Apparatus and method for starting and stopping a plasma arc torch used for mechanized cutting and marking applications
US4668853A (en) Arc-heated plasma lance
US3569661A (en) Method and apparatus for establishing a cathode stabilized (collimated) plasma arc
US3301995A (en) Electric arc heating and acceleration of gases
US4924937A (en) Enhanced electrostatic cooling apparatus
US5464962A (en) Electrode for a plasma arc torch
US6960737B2 (en) Gas flow pre-charge for a plasma arc torch
US2587331A (en) High-frequency electrical heating method and apparatus
US2768279A (en) Electric arc torch apparatus
US3204076A (en) Electric arc torch
US4656330A (en) Plasma jet torch having converging anode and gas vortex in its nozzle for arc constriction
US6734385B1 (en) Microwave plasma burner