JP2980649B2 - Plasma spraying equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma spraying apparatus capable of generating a large-sized plasma jet.

[Conventional statement]

Conventional plasma spraying apparatuses generate plasma with a single pole of + or-direct current and perform thermal spraying. Therefore, large-scale large-scale thermal spraying cannot be performed. Despite efforts to increase speed, this was quite difficult and only some small spraying operations were used. Further, when the thermal spray material hardly enters the center of the plasma and deviates from the center of the plasma, the material does not melt sufficiently and is hit against the object to be sprayed, resulting in poor thermal spraying. Recently, explosive jet flames have been generated by burning gas to enable thermal spraying. However, it has been difficult to obtain a temperature of 2700 ° C. or more, and there was naturally a limit.

More recently, corrosion and development of metal products has rapidly increased due to air pollution, acid rain, and the like. For this reason, the appearance of large-sized large-area thermal spraying for steel frames and other rust prevention has been desired. Multi-arc has proven to be effective in treating and regenerating polluting industrial waste beyond conventional arc welding equipment, but if this principle is applied to plasma spraying, it is stable, large, and small in the conventional narrow area. And various types of thermal spraying beyond the local thermal spraying.

The present invention has been made in view of the above points,
An object of the present invention is to provide a plasma spraying apparatus capable of performing stable thermal spraying over a large area beyond conventional narrow area thermal spraying and capable of performing various thermal spraying.

[Means for solving the problem]

The thermal spraying apparatus according to the present invention includes a neutral electrode and a multi-arc electrode group uniformly arranged on the same plane with the neutral electrode as a center, and electrically connected to the multi-arc electrode group and the neutral electrode. And a power source for generating a voltage for generating a multi-arc between these electrodes.

More preferably, it is desirable to provide the multi-arc electrode group in a plurality of stages in the vertical direction. It is desirable that the arrangement angle of the multi-arc electrode in each stage is shifted so as to generate a multi-arc even between upper and lower electricity.

In addition, a first gas is supplied from the inside of the first cylindrical body containing the neutral electrode toward the opening thereof, and from the inside of the second cylindrical body containing the first cylindrical body toward the opening thereof. A third gas supplied with a second gas and containing the second cylindrical body is provided.
From the inside of the cylinder toward the opening thereof, the first sprayed material and the third
It is preferable that the gas is supplied, and the second spray material and the fourth gas are supplied from the inside of the fourth cylinder housing the third cylinder toward the opening.

It is preferable that the neutral electrode is hollow, and an inert gas, ceramic or fuel gas is ejected from the electrode.

The neutral electrode may be a bundle of wire-like metals, and may be formed of a metal pipe, and the metal to be alloyed may be put in the pipe.

Desirably, a required gas is ejected from the neutral electrode or a circumferential space surrounding the neutral electrode and the counter electrode surrounding the neutral electrode.

The electrode may be configured to generate a triple frequency, sawtooth voltage.

[Action]

According to the present invention, since a multi-arc is generated between the neutral electrode and the multi-arc electrode group evenly arranged on the same plane with the neutral electrode as a center, a strong and stable plasma jet can be obtained.

In the present invention, the multi-arc electrode group is provided in a plurality of stages in the up-down direction, and the arrangement angle of the multi-arc electrodes in each stage is such that a multi-arc is generated even between upper and lower electricity, so that the plasma region is thick and long.

In the present invention, strong plasma spraying can be performed even by using a triple-frequency, sawtooth-wave single-phase output as shown in FIG. 5 instead of a three-phase output.

In the present invention, since the multiple electrodes are arranged in multiple stages, strong plasma spraying can be performed.

In the present invention, the neutral electrode is hollow,
Since the inert gas, air, ceramic, or combustion gas is ejected from the hollow, plasma spraying can be performed easily and efficiently.

In the present invention, the neutral electrode is made to be meltable, and this is made into a bundle of wire-like metal or a metal pipe, and the metal stranded wire to be alloyed is put in the neutral electrode. In addition, it can be performed efficiently.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1A and 1B show a plasma spraying apparatus according to one embodiment of the present invention. In the figure, 1 is a neutral electrode, 2a is a working gas (first gas) in which argon, nitrogen gas, carbon gas or the like is mixed, and 14 is a cylindrical shape having a built-in neutral electrode 1 having a tip portion close to a conical shape. , A first cylindrical body which forms a space A between the first cylindrical body and the electrode 1, and the working gas 2 a flows from the inside of the cylindrical body through the space A to the opening 14 a thereof.
It is supplied to. Reference numeral 15 denotes a second cylindrical body having a cylindrical shape close to a conical shape containing the first cylindrical body 14 and forming a space B between the first cylindrical body 14 and the second cylindrical body 14.
2b passes through the space B from the inside of the cylindrical body and the opening 15a
It is supplied to. 16 is this second cylinder
A third cylinder with a cylindrical shape close to a conical shape containing 15
The first sprayed material 17a such as a metal rod, a wire, a ceramic rod, or a composite of these, or a powdered material, for example, is inserted into the opening 16a through the space C between the cylinder 15 and the inside. In addition, the third gas 2c is supplied. Further, reference numeral 9 denotes a fourth cylindrical body having a cylindrical shape in which the third cylindrical body 16 is incorporated.
The second sprayed material 17b such as Ni, for example, and the fourth gas 2d are supplied from the inside to the opening 9a. Here, the fourth gas 2d may be air. 20 is a plasma jet. Reference numeral 70 denotes a thermal sprayed body, and reference numeral 80 denotes a thermal spray coating.

FIG. 2 shows the electrode arrangement of the plasma spraying apparatus of the above embodiment, and in the figure, 4-1 to 4-6,5-1 to 5-6,6-1.
Reference numerals 6 to 6 denote first, second, and third multi-arc electrode groups in which six electrodes that generate a multi-arc between each other are arranged in the same plane. First
A second multi-arc electrode group is provided between the second cylinders 14 and 15 (space B), and a third multi-arc electrode group is provided between the second and third cylinders 15 and 16 (space C). Is disposed between the third and fourth cylindrical bodies 16 and 9 (space D). The arrangement of the multi-arc electrodes in each group is such that the electrodes are shifted by one phase between the stages so that an arc is emitted between the upper and lower electrodes and a rotating magnetic field is obtained.

In the plasma spraying apparatus of this embodiment, a large cross-sectional area, that is, a thick plasma flow is obtained by the multi-arc between the six electrodes 4-1 to 4-6 in the first plane. Since it is provided over the second and third electrode groups and over three stages, and an arc is generated between the upper and lower stages,
A very powerful and wide-area multi-arc is formed, the plasma region (including the thickness) is large, there is no poor melting, and good quality thermal spraying can be performed. Further, since the plasma flow 20 is very thick and long, large-sized and high-speed thermal spraying can be performed. In addition, since the arc is strong, it is possible to perform thermal spraying of hardly soluble tungsten or alumina. Further, the above mixture can be subjected to thermal and abrasion resistant thermal spraying, and alloy thermal spraying becomes possible. Further, since the present invention is a multi-electrode and has a large circular opening 21 in the middle, a metal rod, a ceramic rod, a ceramic powder in a metal powder, a composite rod 22 or the like is inserted therein to perform thermal spraying. There is the advantage that it can be done.

In addition, since a gas such as an inert gas or air is injected from the space between the cylinders, it is possible to perform thermal spraying by a strong plasma flow. By applying the voltage, the plasma flow can be further enhanced.

Further, the center of the insertion rod 22 is made hollow, and a combustion gas 23 such as an inert gas, air, or acetylene is strongly injected from the hollow, so that thermal spraying using an explosive jet flame can be performed.

Further, in the present invention, since the amount of arc plasma is large, a magnetic field can be generated by an induction coil or the like, and the energy can be increased by accelerating and rotating the generated electrons and ions.

Furthermore, the multi-arc plasma of the present invention is stable and produces good results in reduced-pressure plasma spraying in a reduced-pressure vessel, and the present invention is also effective for spraying in water.

Further, by using the opening 21 to make the arc-generating electrode a metal wire and performing feeding (not shown) in accordance with the consumption, a large amount of thermal spraying, formation of an overlay, or alloying of the wire with a dissimilar metal is performed. Thermal spraying or composite spraying can be performed.

FIG. 3 shows a more specific configuration example of the neutral electrode in the above embodiment.

FIG. 3 (a) shows a neutral electrode made of a poorly soluble metal.
FIG. 3 (b) shows an arrangement in which six electrodes 31a are arranged around the center of 32, and three electrodes 31b are arranged around the neutral electrode 32 made of a poorly soluble metal. is there. In FIG. 3 (c), reference numeral 30 denotes a bundle of wires, which may be made of a dissimilar metal. In this case, the bundle of wires must be strong. FIG. 3 (d) shows a metal pipe 33 in which a stranded wire 34 is inserted in the center, and FIG. 3 (e) shows a metal pipe 33 in which a sparingly soluble tungsten or alumina powder 35 is inserted. FIG. 3 (f) shows a metal pipe 33 in which ceramic powder 36 is put in the center, and FIG. 3 (g) shows a double dissimilar metal pipe 37 surrounding an inert gas 38. In any case, after the metal pipe 33 is melted, the stranded wire, powder, and the like inside can be melted.

The configuration of each neutral electrode has the following effects.

When spraying tungsten or carbon rods, metals and ceramics, or other very insoluble materials, the three electrodes 31
The hardly soluble metal 32 is disposed at the center of the b (FIG. 3 (b)) or the six electrodes 31a (FIG. 3 (a)), and a neutral is connected thereto. Then, an arc is generated between all the electrodes 31 and this neutral hardly soluble metal 32, and an extremely strong arc is generated in combination with the arc between the outer electrodes 31. Can be.

If the center of the hardly soluble welding rod 32 is made hollow and an inert gas, air, ceramic, combustion gas (hydrogen, acetylene, etc.) 39 is blown out from the hollow at an appropriate pressure, the hitherto impossible It is possible to easily and efficiently perform the spraying of the hardly soluble or large powder (for example, naturally occurring iron-broken particles) which has been possible.

Here, in order to more effectively utilize the explosive power of the combustion gas for thermal spraying, it is better to inject the combustion gas at the tip of the electrode rather than at the inside of the electrode. Preferably, it is supplied from the space D between the bodies.

This central neutral electrode 32 is made fusible,
Even if it is made into a wire-shaped metal bundle (Fig. 3 (c)), or a metal stranded wire 34 to be alloyed is inserted into a metal pipe 33 (Fig. 3 (d)), thermal spraying is performed. Can be.
In place of the metal stranded wire 34, a ceramic powder 36 is used.
(FIG. 3 (f)), powder of tungsten, alumina 35, etc. (FIG. 3 (e)) can also be used. Further, an inert gas 38 can be ejected from the inside (FIG. 3 (g)).

In the above embodiment, the six electrodes have a multi-stage configuration, but this may be a single stage. FIG. 4 (a) is a plan view showing a plasma spraying apparatus according to a second embodiment of the present invention having such a configuration. In the drawing, reference numeral 41 denotes six electrodes, reference numeral 42 denotes a neutral electrode, and reference numeral 43 denotes an outer circumferential space surrounding both the electrodes 41 and 42, from which working gas or combustion gas is injected. Reference numeral 44 denotes a further outer circumferential space from which air or the like is jetted.

FIG. 4 (b) shows a modification of the above-mentioned second embodiment, wherein 41 and 42 show the same as those in FIG. 4 (a).
Reference numeral 5 denotes a space surrounding the neutral electrode 42, from which the first inert gas is injected. 46 is the outer six electrodes 41
The second inert gas is jetted from here in the space surrounding.

In this embodiment, the six electrode groups are one stage, but various gases 43, 44, 45, and 46 can be injected from necessary gaps as shown in FIG. The advantages of both gas and jet streams can be used.

5 (a) to 5 (c) show a plasma spraying apparatus according to a third embodiment of the present invention, which obtains a triple frequency, sawtooth wave output from a three-phase alternating current and uses this to perform plasma spraying. Is performed. 5 (a) and 5 (b) are a cross-sectional side view and an external side view of a sprayed portion of the plasma spraying apparatus, wherein 51 is a neutral electrode, 52 is a plasma flow, 53
Is an arc electrode. FIG. 5 (c) shows a configuration for obtaining the output of the triple frequency and sawtooth wave, 51 is a neutral electrode, 53 is three arc electrodes, 38 is a three-phase / single-phase conversion transformer, and 54 is a The primary winding 55 is its secondary winding.

The three-phase / single-phase conversion transformer 58 has three primary coils 54 of three phases wound on the primary side of the single-phase transformer, and one secondary coil 55 wound on the secondary side. For the three primary coils 54 on the secondary side, the power supply of each phase of the three-phase AC power supply
As shown in FIG. 5 (g), the phase is controlled only in the range of about 120 ° to 180 ° by the phase control circuit 24 shown in FIG. 5 (f). As shown, a waveform of a sawtooth wave having a triple frequency is obtained.

In FIG. 5 (f), 1p, 2p, and 3p are three-phase AC power supplies, 25a, 25b, and 25c are thyristors, and 27 is a zero-cross point detector that detects a zero-cross point of a sine wave of each phase of three-phase AC. Vessel, 26a,
26b and 26c are phase adjusters that receive the output of the zero-cross point detector 27 and adjust the firing angles of the thyristors 25a, 25b and 25c of each phase.

In the present embodiment, a triple frequency sawtooth wave is generated on the secondary side of the transformer 58, thereby generating an arc between the three electrodes 53 and the neutral electrode 51, and performing plasma spraying.

FIG. 5 (d) shows a fourth embodiment which is another modification of the embodiment of FIG. 5 (c). This embodiment differs from the third embodiment only on the secondary side. It has two coils 55, 55 on the secondary side, and four electrodes 56, 56, 57, 57 connected to one end of each coil, respectively. In this case, an arc is generated between adjacent electrodes, and plasma spraying is performed.

FIG. 5 (e) shows a fifth embodiment, in which one coil 55 is provided on the secondary side, the neutral electrode 51 and the four electrodes 56 are opposed to each other, and all of the four electrodes 56 are connected to each other. The secondary voltage of the secondary coil 55 is applied between the neutral electrode 51 and the neutral electrode 51. In this case, the neutral electrode 51
An arc is generated between the electrode and the four electrodes 56, and plasma spraying is performed.

In the third, fourth, and fifth embodiments of the present invention, the central electrode 51 (but not the central electrode in the fourth embodiment) is made thicker by a non-consumable electrode, and The electrode 53 divided into three or more parts is made thinner, a sawtooth wave of a triple frequency is obtained from a three-phase alternating current by a transformer 58, and this is applied between the electrodes, thereby simultaneously generating an arc and performing thermal spraying. With this configuration, a powerful arc can be efficiently generated for power conversion, and plasma spraying can be performed. In addition, since the operation of converting the three phases into a single phase is symmetrical with respect to the three phases, there is no problem in which the three phases are unbalanced, and a great effect can be obtained as compared with the related art.

Further, since the central electrode 51 is made hollow, and necessary materials such as inert gas, air, combustion gas, ceramics and the like are radiated and sprayed, plasma spraying can be performed simply and efficiently.

Further, as described above, the central electrode as a consumable electrode, it is also possible to perform thermal spraying to supply power to it, and further, a part of each of the above electrode configurations, a consumable electrode,
A part may be a non-consumable electrode, and an electrode forming an arc atmosphere and a sprayable electrode may be used.

Further, for example, the four electrodes of the configuration of the fourth embodiment are arranged in upper and lower stages,
Alternatively, it is further shifted by one electrode in many stages,
If the thermal spraying is performed so that an arc is generated between the electrodes of each stage and between the electrodes of each stage, more powerful plasma spraying can be performed.

FIG. 6 is a schematic view showing the configuration of a triple frequency, sawtooth wave arc spraying apparatus according to a sixth embodiment of the present invention. In the figure, reference numeral 61 denotes a neutral electrode, 62a includes the neutral electrode 61, A first cylindrical electrode body having a tip portion close to a conical cylinder, 62b includes the first cylindrical electrode body 62a, a second cylindrical electrode body having a tip portion close to a conical cylinder, 63 is an inert gas,
64 is air, 65 is a melting wire, and 66 is a container. In the present embodiment, the triple frequency and sawtooth wave obtained by using the three-phase / single-phase conversion transformer are applied between the cylindrical electrode bodies 62a and 62b and the neutral electrode 61, and an arc is generated between the two. By melting the molten wire 65 with this arc,
Arc spraying can be performed. Further, if a DC voltage is applied to the first and second cylindrical electrode bodies 62a and 62b so that the voltage of the outer one becomes higher, the force for pulling the arc toward the opening side increases, and thermal spraying with a strong arc can be performed. it can.
The melting wire 65 may be replaced with, for example, one of the electrodes. Instead of triple frequency and sawtooth waves, ordinary single-phase alternating current or direct current may be applied between the electrodes.

〔The invention's effect〕

As described above, according to the present invention, since the multi-arc is generated between the neutral electrode and the multi-arc electrode group evenly arranged on the same plane with the neutral electrode as a center, the multi-arc is generated. Thus, there is an advantage that a stable plasma jet can be obtained, and a material that could not be sprayed so far can be sprayed over a large area.

[Brief description of the drawings]

FIG. 1 is a diagram showing a plasma spraying apparatus according to one embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of multiple electrodes in the above embodiment, and FIG. 3 is a diagram showing a specific configuration of a neutral electrode in the above embodiment. FIG. 4, FIG. 4 is a diagram showing a second embodiment of the present invention, FIG. 5 is a diagram showing third, fourth, and fifth embodiments of the present invention, and FIG. It is a figure which shows the Example of. In the figure, 1, 32, 51, 61 are neutral electrodes, 2a is a working gas (first gas), 2b is a second gas, 2c is a third gas, 9 is a fourth cylinder, 14 is a first cylinder, 15 is a second cylinder, 16 is a third cylinder, 17a is a first spraying agent, 17b is a second spraying agent, 2d is air (fourth gas), 20, 52 is a plasma flow, 30 is a wire, 31 is a wire, 31a, 41
Is 6 electrodes, 31b is 3 electrodes, 42 is neutral electrode, 43-4
6 is a gas injection space, 53 is an arc electrode, 58 is a three-phase to single-phase conversion transformer, 54 is its primary winding, 55 is a secondary winding, 61 and 62 are first and second electrode bodies, and 64 is air Reference numeral 63 denotes an inert gas, and reference numeral 65 denotes a melting wire. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (9)

(57) [Claims] 1. A multi-arc electrode group comprising: a neutral electrode; and a multi-arc electrode group uniformly arranged on the same plane with the neutral electrode as a center, and electrically connected to the multi-arc electrode group and the neutral electrode. And a power supply for generating a voltage for generating a multi-arc between the electrodes. 2. The plasma spraying apparatus according to claim 1, wherein said multi-arc electrode group is provided in a plurality of stages in a vertical direction. 3. The plasma spraying apparatus according to claim 2, wherein the angle of arrangement of the multi-arc electrodes in each stage is shifted so as to generate a multi-arc even between upper and lower electricity. 4. The plasma spraying apparatus according to claim 1, wherein the first gas is supplied from the inside of the first cylindrical body containing the neutral electrode toward an opening thereof. The second gas is supplied from the inside of the second cylindrical body having the inside into the opening thereof, and the first spray material and the third spraying body from the inside of the third cylindrical body having the second inside the body. The third gas is supplied, and the second spray material and the fourth gas are supplied from the inside of the fourth cylindrical body containing the third cylindrical body to the opening thereof. Plasma spraying equipment. 5. The plasma spraying apparatus according to claim 1, wherein said neutral electrode is hollow, and an inert gas, ceramic or fuel gas is ejected from said neutral electrode. A plasma spraying apparatus. 6. The plasma spraying apparatus according to claim 1, wherein said neutral electrode comprises a bundle of metal wires. 7. The plasma spraying apparatus according to claim 1, wherein said neutral electrode comprises a metal pipe, and said pipe contains a metal to be alloyed. Plasma spraying equipment. 8. The plasma spraying apparatus according to claim 1, wherein said neutral electrode comprises:
Alternatively, a required gas is ejected from a peripheral space surrounding the neutral electrode and a counter electrode surrounding the neutral electrode. 9. A plasma spraying apparatus according to claim 1, wherein said power source is configured to generate a triple frequency, sawtooth voltage. A plasma spraying apparatus characterized in that the plasma spraying is performed.