JPS61149265A - Plasma torch for flame spraying - Google Patents

Abstract

PURPOSE:To efficiently heat and accelerate a powder by sending the same in the central part of a plasma flame, by providing a supply hole of gas or a powder to a double cylindrical electrode along the center line of the inside electrode of said cylindrical electrode. CONSTITUTION:Voltage from a plasma power source 16 is applied between an outside electrode 13a and an inside electrode 13b to generate an arc 25 between both electrodes. This arc 25 is moved left and right while the cylindrical electrodes 13a, 13b are rotated by an arc rotary drive coil 14, an upstream side arc control coil 15a, a downstream side arc control coil 15b and a controller 20. A power supply pipe 27 is integrally formed to an electrode support cylinder 8 and, if a powder of a metal or ceramic is supplied to the central part of a plasma flame 26 through the powder supply pipe 27, the powder is entirely heated and accelerated with good efficiency and the loss of the power becomes extremely little and the properties of a flame spray film are enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is intended to be applied to plasma torches, laser generators, and chemical reaction electrodes that utilize discharge energy.

[Conventional technology]

The configuration of a conventional non-transfer type plasma torch for thermal spraying is shown in Fig. 1, where 01 is a nozzle and 702 is a nozzle θ.
Water-cooled outer cylinder connected in a watertight structure with 03, 4 nozzle cooling water supply tubes, 04 nozzle cooling water discharge mother tube, 0
6 is the working gas chamber, 0.6 is the working gas outlet, θ7
08 is the electrode support tube, 09 is copper. Electrode made of tungsten, hafnium, and zirconium, 010 is electrode cooling water conduit, 011 is electrode cooling water supply pipe, 012 is electrode cooling water discharge) 4 Eve, θ13
014 is a plasma power supply, 015 a is a connecting ring made of an electrical insulator that connects the nozzle θ and the electrode support cylinder 08.
, 0.15b is a power line connecting the plasma power source 014 and the nozzle θ or the electrode support tube 08.

Also, 016m and 016b are the nozzle cooling water flow paths 01
7m, 017b is the working gas flow path, 018B, 018b
, 018c is a flow path for electrode cooling water.

Furthermore, 019m and 019b are arcs, 020 is a plasma flame, 02 is a feed pipe for gas powder, etc., and 022 is a feed flow path for gas powder, etc.

The voltage from the plasma power source θ14 is the power line θ15a, θ1
5b between the electrode o9 and the nozzle 01, an arc occurs during this time, but at the same time, the working gas is supplied from the working gas supply t4 to the working gas chamber o5,
Working gases such as argon, hydrogen, nitrogen, oxygen, and air are supplied into the nozzle 01 through the working gas outlet 06 as shown by arrows 017a and 017b, so these gases are heated by the arc 19a and generate a plasma flame 020. let

Furthermore, when metal powder, ceramic powder, etc. are fed into the plasma flame 020 from the powder supply pipe 021, these powders are heated and accelerated, colliding with the object to form a sprayed layer.

In this case, the nozzle 01 and the electrode 09 are heated by the arc 019a, so the arrows 016m and 016 lead from the nozzle cooling water supply vibrator 03 to the nozzle cooling water discharge nozzle o4.
Nozzle cooling water shown in b and electrode cooling water supply pipe 0
1, an arrow θ18a leading to the electrode cooling water conduit 010, the electrode support 808, and the electrode cooling water discharge mother pipe 012;

The electrodes are cooled by cooling water showing θ18b, 018cK.

In this way, the conventional plasma torch has electrode 09 and nozzle θ
An arc 019a is generated between the electrode 09 and the nozzle 01, but in a steady state, the arc is blown by the working gas 017b and there is a high probability that the arc will occur between the tip of the electrode 09 and the outlet end of the nozzle 01 as shown in 019b. Since the generation point is limited, nozzle cooling water is required.
Currently, the lifespan of the electrode 09 and the nozzle θ is extremely short despite being cooled by the electrode cooling water 16a or the electrode cooling water 018R, respectively.

Therefore, when working with a conventional plasma torch,
It was extremely inefficient as it required frequent interruptions to replace electrodes and nozzles. In addition, since the powder is fed from the outside of the plasma flame 020, the powder at the same ratio does not reach the high temperature part of the plasma flame θ20, that is, it collides with the object without being heated, so its adhesion is weak and it may fall off. ,
It seemed to have gotten caught up in the sprayed layer. For this reason, expensive powders were not used effectively, and the properties of the thermally sprayed layer itself were inferior.

[Problem that the invention seeks to solve]

The present invention extends the life of the electrode and nozzle of a non-transfer type plasma torch, improves workability, and improves the efficiency of melting by providing a means for efficiently feeding the powder into the plasma flame. The aim is to improve the performance of thermal sprayed coatings.

[Means for the invention to solve the problem]

Water-cooled pipes are installed in both the outer and inner cylinders, and the inner surface of the outer cylinder and the outer surface of the inner cylinder are used as electrodes to generate an arc between the two, and a drive coil is installed near the electrodes. This generates lines of magnetic force parallel to the axial direction of the cylindrical electrode. At this time, according to Fleming's left-hand rule, the arc receives a force in the circumferential direction and rotates on the cylindrical electrode.

Furthermore, if magnetic lines of force parallel to the circumferential direction are generated by position control fills provided near both ends of the cylindrical electrode, the shear arc will be subjected to a force in the axial direction of the cylindrical electrode according to Fleming's left-hand rule.

Therefore, assuming that current flows from the outer cylinder electrode to the inner cylinder electrode, if the plasma torch is viewed from the upstream side of the working gas and generates magnetic lines of force in the clockwise direction, the arc will move upstream of the working gas and counterclockwise. If a rotating magnetic field line is generated, it will move downstream.

If two position control coils installed near both ends of the cylindrical electrode generate clockwise lines of magnetic force on the downstream side and counterclockwise lines of magnetic force on the upstream side, the arc will rotate without coming off the electrode.

By increasing/decreasing the strength of the magnetic lines of force by the position control coils on the upstream side and the downstream side, respectively, with a phase shift of 180 degrees, the arc will rotate while moving in the upstream and downstream directions.

Therefore, since the arc moves uniformly over a wide range of the cylindrical electrode, electrode wear is dispersed and a long life of the plasma torch electrode is achieved.

In addition, if the powder is fed through the powder feeding hole provided along the center line of the inner cylinder, the powder can be fed directly to the center of the plasma flame, making it possible to efficiently heat and accelerate the powder. Abnormal consumption due to powder contamination can be prevented.

[Effect]

As shown in FIG. 2, the voltage from the plasma power supply 16 is applied to the outer electrode 13a (the electrode formed on the inner surface of the nozzle 1) and the inner electrode 13b (the electrode formed on the inner surface of the nozzle 1) through the power lines 17a, llb, the nozzle 1, and the electrode support tube 8. An arc 25 is generated between the electrodes 13s and Isb. The plasma power source 16 may be an AC power source or a DC power source, but the outer electrode 1.7 a is a DC power source.
The explanation will be made assuming that the inner electrode 13b is connected to the positive wire and the inner electrode 13b is connected to the negative wire.

That is, the arc 25aK is from the outer electrode 13m to the inner electrode 13.
Current flows towards b. In this case, the arc rotation drive coil 14 generates a magnetic force i that penetrates the entire arc 25m from right to left.

Therefore, as the arc 25aFi receives a force directed upward from the plane of the paper according to Fleming's left-hand rule, it rotates along the cylindrical outer electrode 13a and inner electrode 13b with a result of 1-.

Furthermore, since the upstream arc control coil 15a can generate upward lines of magnetic force for the arc 25a through the plane of the paper, the arc 25m receives a force in the right direction according to Fleming's left-hand rule.

In this way, the upstream arc control coil 15. Since the a and downstream arc control coils 15b can apply forces in opposite directions to the arc 258, the controller 20 increases or decreases the current flowing through the upstream and downstream control coils 15a and 15b with a total phase shift of 180°. Then arc 25ail-
j: Forces are applied alternately to the right and to the left.

Therefore, the arc rotation drive coil 14, the upstream arc control coil 15a1, the downstream arc control coil 15b, and the suppressor 2
0, the arc 25a is connected to the cylindrical electrodes 13a, 1
3 While rotating b, you will also be moving left and right.

At the same time, the working gas 23a is supplied, and the nozzle 1 and the electrode support tube 8 are cooled by the cooling water 22m and 23a.
This effect is similar to that shown in FIG.

The case where the plasma flame 26'tl- is generated using the DC plasma power supply with the outer electrode 13B being positive has been described above.
If the inner electrode 13bf is made positive, the movement of the arc 25m will be reversed, so this can be dealt with by reversing the direction of the current flowing through all the coils.

When using an AC plasma power source, the current switching controller 2
1, if the direction of the current flowing through the fill is reversed according to the direction of the plasma current, the same effect as in the case of a DC power source can be obtained.

When powder of metal, ceramic, etc. is fed to the thus formed plasma flame 26 through the powder feed pipe 27, the powder is heated and accelerated, colliding with the object to form a thermal spray m.

〔Example〕

As shown in Fig. 2, 1 is a nozzle, 2Fi is a water-cooled outer cylinder connected to the nozzle 1 in a watertight structure, and 3 is a nozzle cooling water supply/tube.
4 is a nozzle cooling water discharge pipe, 5 is a damper for operation, 6 is a working gas outlet, 7Fi is a working gas supply i
4 and 8 are electrode support cylinders that are integrated with the powder supply pipe 27. 9 is an electrode cooling water conduit, 10 is an electrode cooling water supply main tube, 11 is an electrode cooling water discharge main tube, 12 is a connecting ring made of an electrical insulator that connects the nozzle 1 and the electrode support cylinder 8, 13a is an outer electrode made of copper, tungsten, hefnium, zirconium, or conductive ceramics. JJb is an inner electrode made of the same material as the outer electrode 13B, and the outer electrode 13a and the inner electrode 13b are arranged concentrically.

Reference numeral 14 indicates an arc rotation drive coil that generates lines of magnetic force parallel to the axis between the two electrodes 138 and 13b, and 15m indicates an arc rotation drive coil provided adjacent to the arc rotation drive coil 14 on the upstream side of the working gas and both electrodes 13a.

Between 13b and 1, there is an upstream arc control coil that generates lines of magnetic force parallel to its circumference; 15b is the same downstream arc control coil; 16 is a plasma power source; Connecting power lines 18, power supply for arc rotation drive coil 14, 19a, 1
9b are upstream and downstream arc control coils 15a, respectively.

15b is a power source, 20 is an upstream and downstream arc control coil power source, 19a and 19b are controlling controllers, and 21 is a current switching controller.

Further, 22a and 22b are nozzle cooling water flow paths, 23m, 23
b is a working gas flow path 24a;

24b, 24c are electrode support tube cooling water flow paths, 25B, 2
5b is an arc flow path, 26 is a plasma flame, 27 is a powder supply pipe, and 28 is a powder supply flow path.

〔effect〕

As detailed above, according to the present invention, the arc rotates along the cylindrical electrode and reciprocates along the axial direction, so the electrode is not locally heated and its life can be dramatically extended. The number of interruptions in operation for replacement is small. In addition, since the powder can be fed into the center of the plasma flame, all the powder can be efficiently heated and accelerated. Therefore, powder loss is extremely small and the performance of the sprayed film is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional thermal spraying plasma torch, and FIG. 2 is a sectional view showing an example of the thermal spraying plasma torch of the present invention. θ1.1... Nozzle, 08.8... Electrode support tube, 0
9... Electrode, 13a... Outer electrode, 13b... Inner electrode, 14... Arc rotation drive coil, 15a...
- Upstream arc control coil, 15b... Downstream arc control coil, 27... Powder supply hole, 28... Powder feed flow pipe. Applicant Sub-Agent Patent Attorney Suzue Takehiko Procedural Amendment Showa, 6Ql! 5.2 Enemy 8 Manabu Shiga, Commissioner of the Japan Patent Office1, Indication of the case, Patent Application No. 1971-2718332, Name of the invention: Plasma torch for thermal spraying3, Relationship with the person making the amendment Patent applicant (620) Mitsubishi Heavy Industries Co., Ltd. 4, successor manager 6, specification subject to amendment 7, content of amendment (1) Page 1 of the specification, lines 15 to 17, “
The present invention is to... '' should be corrected to read ``The present invention is intended to be applied to plasma spraying plasma torches and chemical reaction plasma torches for thermal spraying of metal powders, ceramic powders, or mixed powders thereof.'' (8) On page 2, line 2 i1, the statement "022 is for gas powder, etc." is corrected to "022 is for powder, etc." (4) In the fourth line of page 5, the phrase "also in the sprayed layer itself" is corrected to "also in the sprayed layer itself." (5) On page 8, line 7, the phrase ``throughout and upward'' is corrected to ``throughout and downward''. (6) On page 8, line 9, the phrase ``following to the right'' is corrected to ``following to the left j''.

Claims (1)

[Claims] an arc rotation drive coil adjacent to the double cylindrical electrodes for arc discharge to generate lines of magnetic force parallel to the axial direction of the electrodes; and an arc rotation drive coil adjacent to the drive coil to generate lines of magnetic force along the circumferential direction of the electrodes. 1. A thermal spraying plasma torch, characterized in that it is provided with an arc control coil that generates an arc, and that a gas, powder, etc. feeding hole is provided along the center line of the inner electrode of the double cylindrical electrode.