KR101041887B1 - Nontransferred plasma torch having constricted electrode - Google Patents

Abstract

PURPOSE: A non-transferred type plasma torch having a shrinkage type electrode part is provided to stabilize an arc discharge by generating flow rotation in an arc chamber within a downstream electrode part. CONSTITUTION: A ring member(3) and an insulator(4) are formed between the downstream electrode part(1) and upstream electrode part(2). The ring member comprises a plurality of orifices(11) which are formed according to a circumferential direction in order to supply actuating gas in a vortex shape. The insulator electrically insulates the downstream electrode part and the upstream electrode part. The arc chamber is formed in a hollow structure of the downstream electrode part. The upstream electrode part is composed of a hollow or a button type electrode having a larger diameter than the downstream electrode part. A reduced region unit(5) is formed in the upstream electrode part within the downstream electrode part. An extended region part(6) is formed at the exit of the downstream electrode part.

Description

Non-Convertible Plasma Torch with Shrink-type Electrode [NoNTRANSFERRED PLASMA TORCH HAVING CONSTRICTED ELECTRODE}

The present invention relates to a cavity-type non-feed plasma torch that produces a stable high temperature and high velocity plasma flow.

The arc plasma torch is supplied with direct current power. Arc plasma torches can be divided into two types: nontransferred and transferred arcs. These consist of the following.

-Cathode where electrons are emitted

-Plasma Gas Injection System

A nozzle defining a plasma region;

In a non-conveying arc plasma torch, the positively polarized nozzle becomes the anode. In the case of a transfer arc plasma torch, the material being treated is the anode, and the nozzle is at the floating potential.

The arc is ignited between the cathode and the anode and ionizes the plasma gas. The central portion that enables plasma applications varies up to 15000K.

In the treatment of a target object by arc plasma, the prior art applies a plasma torch for high temperature heating in an atmosphere of atmospheric pressure (760 Torr) or lower (1 mTorr to 100 Torr).

Therefore, the conventional non-feed type plasma torch having a cavity type electrode has a problem in that the pressure and temperature at the front end of the object to be processed cannot be raised together because the flow flow is low speed, that is, subsonic speed.

The present invention devised to solve such a problem is to provide an efficient plasma torch that produces a stable high temperature and high speed arc plasma flow in order to increase both the pressure and the temperature in front of the object to be treated.

The present invention for achieving the above object, and the front electrode portion provided with a cavity to form an arc chamber therein; A rear electrode part disposed to have a predetermined gap with the front electrode part, and having a cavity having a diameter larger than that of the front electrode part; And a ring member disposed between the front electrode portion and the rear electrode portion to electrically insulate the two electrodes, the cavity having the orifice through which the working gas supplied to the arc chamber passes, and electrically insulate both of them. The negative arc chamber forms an inlet portion through which the working gas flows, and constrains the working gas and the arc column to increase the amount of heat applied to the working gas, and has a narrow area with a relatively narrow diameter, and an arc length in the axial direction. In order to stabilize the change, the expansion region portion having a relatively larger diameter and length than the reduction region portion, and the outlet portion through which the arc is discharged, are contracted to form a supersonic arc plasma flow and a high pressure arc chamber pressure. Choke Throat, and the nozzle portion consisting of a diffusion structure and the front electrode reduced region portion and The extended area portion and the nozzle portion all form a cavity,
The arc chamber of the rear electrode portion has a larger inner diameter than the cavity of the front electrode portion, and rotates the arc ground point in the rear electrode portion to adjust the position of the axial arc branch point and the arc to the end of the rear electrode portion. Magnetic spin coils to prevent the transition is located on the outer circumference of the outside of the rear electrode portion, characterized in that the arc voltage is kept constant or increases with the current-voltage characteristic as the arc current increases.

In addition, the non-feedable plasma torch having the shrinkable electrode part of the present invention is composed of an inner cooling water path located at the wall surface side of the arc chamber of the front electrode part and the rear electrode part and an outer cooling water path located at the outer side thereof. A cooling water passage is provided, wherein the inner cooling passage is formed in a shape surrounding the arc chamber, and a plurality of irregularities are formed on the cooling wall, and the outer cooling passage is formed in a manner surrounding the inner cooling passage. Cooling water passing through the flow is characterized in that the cooling water inlet and the outlet is located on the same cross-section by the dual cooling water passage.

delete

delete

In addition, according to the non-feeding plasma torch having the shrinkable electrode part of the present invention, a plurality of orifices formed in the ring member are introduced while the working gas is rotated in the circumferential direction to circumferentially arc and arc divergence points of the front electrode part by aerodynamic force. It is formed at an angle forming a circumferential tangential at right angles to the inner radial direction of the ring member to rotate in the direction, has an orifice inner diameter so that the flow velocity is smaller than the speed of sound without choking the working gas flow occurs, the ring member Is characterized in that formed in a symmetrical structure with respect to the arc chamber axial direction.

Cavity non-feed plasma torches to which the present invention is applied produce stable high temperature and high velocity plasma flow. This has the effect of simultaneously increasing the pressure and temperature at the object or sample front end plasma treatment.

1 is a longitudinal sectional view schematically showing a non-conductive plasma torch having a shrinkable electrode part according to the present invention.
2 is a longitudinal cross-sectional view and a side cross-sectional view showing a ring member and an orifice structure which are main components of the present invention.
FIG. 3 shows a cooling water channel as a longitudinal section for the line AA of FIG. 1.

The present invention will now be described in detail with reference to the accompanying drawings.

1 is a longitudinal sectional view showing a nontransfered plasma torch having a shrinkable front electrode portion according to an embodiment to which the present invention is preferably applied and having a shrinkage diffusion nozzle at a front end thereof.

The plasma arc used by the cavity-type non-feeding plasma torch has a severe fluctuation in the axial direction due to the arc branching characteristic in the electrode, so the present invention provides a means for stabilizing the arc during the development of the plasma torch.

In addition, in order to make high-speed flow in the plasma torch, the internal pressure of the arc chamber must be increased. In order to increase the pressure of the arc chamber, the flow rate of the working gas must be increased while maintaining the high temperature. The heat from the arc is efficiently applied to the working gas from the arc, thereby raising the temperature of the plasma flow.

In the present embodiment, the plasma torch has a swirl between the front electrode part 1 and the downstream electrode part 2, and the upstream electrode part 2, and between the front electrode part 1 and the rear electrode part 2. The ring member 3 and the insulator 4 are provided with a plurality of orifices 11 along the circumferential direction to supply the working gas in a shape. The insulator 4 provides the front electrode part 1 and the rear electrode part. (2) is electrically insulated.

The front electrode part 1 is hollow and an arc chamber is formed therein, and the rear electrode part 2 is a cavity or button type electrode having a relatively larger diameter than the front electrode part 1. It consists of.

In the internal structure of the front electrode portion 1, a narrowed region portion 5 having a smaller diameter is formed on the rear electrode portion 2, and an expanded region portion 6 having a larger diameter is formed on the exit side.

More specifically, the reduced area portion 5 of the front electrode portion 1 narrows the cross-sectional area and constrains the actuating gas and the arc column passing through the portion to the narrow passage, thereby reducing the amount of heat applied from the arc to the actuating gas. Increase the arc length to the boundary region portion 13 where the reduced region portion 5 ends and the extended region portion 6 starts, in a structure that extends from the reduced region portion 5 to the expanded region portion 6. The hydrodynamic force in the resulting arc flow allows the arc branch point to stay in the boundary region 13, which is the starting region of the extension region 6.

In addition, the internal shape of the arc chamber increases the heat flux of the flow and reduces the axial flow fluctuation due to the arc branching characteristic generated at the arc contact, thereby stabilizing the plasma arc flow.

On the other hand, since the heat transfer to the wall surface of the reduced region portion 5 and the expanded region portion 6 is high, it is necessary to cool the entire front electrode portion 1 with a high-pressure cooling water. In order to increase the cooling efficiency, as shown in FIG. 3, the outer cooling water passage 15 located radially outward on the concentric longitudinal section and the inner side of the outer cooling water passage 15 are located inside the wall surface of the front electrode unit 1. It is configured to have a structure with a double cooling water located in the inner cooling water passage 14, the cross-sectional shape is irregular. In this way, a plurality of uneven portions are formed on the cooling wall surface of the inner cooling water passage 14 inside the wall near the arc chamber of the front electrode part 1 to increase the cooling water contact area, and the structurally high arc chamber pressure and the cooling water pressure. I can endure it. Then, the coolant introduced through the coolant inlet is returned to the outlet due to the coolant inlet and the outlet located on the same cross section. Accordingly, the cooling water inflow and outflow structure can be simplified.

On the other hand, the outlet portion of the front electrode portion 1 is provided with a water-cooled shrinkage diffusion nozzle portion 7 to increase the pressure of the arc chamber inside to create a high-speed plasma arc flow at the outlet.

The plasma arc at the nozzle portion 7 is the chocking Throat (8), the flow reaches the speed of sound and the area ratio of the exit 9 and the choking neck (8) at the end of the nozzle diffusion portion and the diffusion angle of the nozzle, The static pressure in the flow passing through the nozzle outlet 9 is designed to be equal to or higher than the ambient pressure so that flow separation does not occur in the nozzle diffusion.
The choking neck 8 refers to a throat having a minimum cross-sectional area where a choking phenomenon may occur in the nozzle unit 7. When the choking increases the flow velocity of the gas body caused by the pressure difference, the flow velocity at the minimum cross section of the flow passage increases, but the velocity reaches the sound velocity. It does not increase beyond that.

In order to increase the speed of the arc flow passing through the nozzle outlet 9, the peripheral static pressure may be lower than the pressure at the nozzle outlet 9 or the pressure and temperature inside the arc chamber may be increased.

The pressure and temperature inside the arc chamber can be adjusted by controlling the arc current, arc voltage, or working gas flow rate.

Some new material manufacturing processes inject powder or liquid raw materials directly into the arc chamber, where they are placed directly upstream or downstream of the nozzle neck 8.

Meanwhile, a high-pressure working gas is introduced into the arc chamber, and as shown in FIG. 2, the front electrode part 1 and the rear electrode part through a plurality of orifices 11 orifices in the ring member 3. In the gap between (2), the working gas is injected evenly in the tangential direction of the inner diameter, forming a vortex. Preferably, the orifices 11 are formed of four to eight, and the working gas is uniformly injected into the arc chamber at subsonic speed through the orifices 11.

As a result, a flow rotation occurs in the arc chamber in the front electrode part 1, and as a result, the arc column is constrained to the central axis region by the radial pressure gradient to stabilize the arc discharge.

Meanwhile, when the rear electrode part 2 is a cavity type, a magnetic spin coil 12 is positioned at an outer circumference of the outside of the rear electrode part 2, and the magnetic rotation coil 12 is a rear electrode part ( 2) It acts to rotate the arc foot termination in this position, thereby making it possible to adjust the axial arc branch point position. In addition, the magnetic rotating coil 12 also serves to prevent the arc transition to the end of the rear electrode portion (2).

The pressure of the arc chamber of the plasma torch is measured at the end wall portion 10 of the rear electrode portion 2.

1: front electrode
2: rear electrode
3: ring member
4: insulator
5: reduced area
6: extended area
7: nozzle
8: choking neck
9: nozzle outlet
10: pressure measuring unit
11: orifice
12: Magnetic rotating coil
13: boundary area
14, 15: with cooling water

Claims (5)

A front electrode part having a cavity forming an arc chamber therein; A rear electrode part disposed to have a predetermined gap with the front electrode part, and having a cavity having a diameter larger than that of the front electrode part; And a ring member disposed between the front electrode portion and the rear electrode portion to electrically insulate the two electrodes so that the cavities are continuous, and an orifice through which an operating gas supplied to the arc chamber passes.
The arc chamber of the front electrode portion has an inlet portion into which the working gas flows, and constrains the working gas and the arc column so as to increase the amount of heat applied to the working gas, and has a reduced area portion having a relatively narrow diameter and an axial direction. In order to stabilize the arc length and change, the expansion zone portion having a larger diameter and length than the reduction zone portion and the outlet portion through which the arc is discharged are formed, and the arc plasma flow at high speed and the arc chamber pressure at high pressure are formed. It consists of a nozzle portion consisting of shrinkage, choking throat, and diffusion structure, as well as the reduction region portion, the expansion region portion and the nozzle portion of the front electrode portion as a whole,
The arc chamber of the rear electrode portion has a larger inner diameter than the cavity of the front electrode portion, and rotates the arc ground point in the rear electrode portion to adjust the position of the axial arc branch point and the arc to the end of the rear electrode portion. Magnetic spin coils to prevent the transition is located on the outer periphery outside the rear electrode,
A non-transportable plasma torch having a contraction type electrode portion having a current-voltage characteristic in which the arc voltage is kept constant or increases with increasing arc current. delete The method of claim 1,
A dual cooling water path comprising an inner cooling water path located at a wall surface side that forms an arc chamber of the front electrode part and a rear electrode part, and an outer cooling water located at an outer side thereof;
The inner cooling water passage is formed in a shape surrounding the arc chamber, and a plurality of irregularities are formed on the cooling wall.
The outer coolant has a shape surrounding the inner coolant so that the coolant passing through the inner coolant flows.
A non-feedable plasma torch having a shrinkable electrode portion, characterized in that the cooling water inlet and the outlet are located on the same cross section by the dual cooling water passages. delete The method of claim 1,
A plurality of orifices formed in the ring member flows in the circumferential direction while the working gas flows in the circumferential direction so as to circumferentially circumferentially perpendicular to the inner radial direction of the ring member to rotate the arc and the arc branch point of the front electrode portion in the circumferential direction by aerodynamic force. Formed at an angle,
It has an orifice inside diameter that does not cause choking of the working gas flow and makes the flow rate smaller than the speed of sound,
And the ring member is formed in a symmetrical structure with respect to the arc chamber axial direction.

Images