JP2010043341A - Composite torch type plasma generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify and miniaturize a sub-torch as a whole by reducing the number of components of the sub-torch, and to increase plasma output by enhancing the direct-advancing property and stability of plasma and plasma flame. <P>SOLUTION: A composite torch type plasma generator comprises a main torch 1 and the sub-torches 2, the main torch and the sub-torches, each of which has a cathode, an anode and a plasma gas supply means. In the plasma generator, several sub-torches 2, 39 are disposed on radial lines around the main torch axial center, and the anodes 10A, 40 of the respective sub-torches 2, 39 are surrounded by outer sheathes 11, 41. The internal walls of the outer sheathes 11, 41 are provided with cathodes. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a composite torch-type plasma generator, and more specifically, a large current flowing in a gas, a so-called arc, and a high-temperature plasma around 10,000 ° C. generated thereby, such as metal or ceramics. The present invention relates to an improvement in so-called plasma spraying technology for melting a substance and spraying it on an object to be processed to form a strong film on the surface. In recent years, this stable high-temperature plasma has been used as a heat source for thermal shock tests and gas decomposition of ceramics.

FIG. 4 shows a main part of a conventional general-purpose composite torch type plasma spraying apparatus.
In FIG. 4, the main jacket 4 and the main second jacket 31 each having an emission port on the axis of the main cathode 3, and the insulator 27 and the insulator 29 having the swirling gas forming means 52 are concentrically held.

  As shown in FIG. 2, the main plasma gas 6 is first fed into the gas annular chamber 53 from the main plasma gas inlet 5 to form one swirl flow forming hole 54 or a plurality of swirl flow arranged equally. It passes through the hole 54 and is fed as shown by an arrow 56 so as to turn the inner wall 55 of the insulator 27. Similarly, the main second gas 33 is also fed through the main second gas inlet 32 to swivel the inner wall of the insulator 29.

  The negative terminal of the main power supply 7 is connected to the main cathode 3, and the positive terminal of the main power supply 7 is connected to the main outer jacket 4 via the switch means 8 and to the main second outer jacket 31 via the switch means 34, These constitute the main torch 1 as a whole.

  Next, there is a sub-torch activation electrode 10 arranged so as to intersect with the central axis of the main torch 1, that is, the central axis of the main cathode 3. The auxiliary mantle 11 and the auxiliary second mantle 36 are concentrically held by the insulator 28 and the insulator 30 having the swirl gas forming means similar to the insulator 27 of the main torch 1.

  The secondary power source 14 has its positive terminal connected to the secondary mantle 11 and the positive terminal of the main power source 7 via the switch means 15, and the negative terminal of the secondary power source 14 is connected to the secondary torch starting electrode 10. Constitutes the auxiliary torch 2 as a whole. The main torch 1 and the sub torch 2 are fixed by a connecting pipe 26, and each has a structure that can be easily detached and kept insulative.

  In FIG. 4, an inert gas such as argon is flowed from the main plasma gas inlet 5 as the main plasma gas 6, the switch means 8 and the switch means 34 are opened, the switch means 8 is closed, and the high frequency of the main power supply 7. Is applied between the main cathode 3 and the main mantle 4 to form a main starting arc 16 from the tip of the main cathode 3 toward the outlet of the main mantle 4, thereby heating the main plasma gas 6 and plasma 18. And is discharged from the tip of the main mantle 4.

  Further, by closing the switch means 34 and opening the switch means 8, the anode point of the plasma 18 is transferred from the main mantle 4 to the main second mantle 31, a main second starting arc is formed, and the main second mantle is formed. It is discharged from the tip of 31 toward the outside of the main torch 1.

  Next, the switch means 15 is closed and applied between the auxiliary torch starting electrode 10 and the auxiliary mantle 11 by the high frequency of the auxiliary power source 14, and inert gas such as argon is used as the auxiliary gas 13 from the auxiliary gas inlet 12. When the gas is sent in, the secondary starting arc 17 is generated, and the plasma 18 is ejected from the outlet of the auxiliary second mantle 36 through the outlet of the tip of the auxiliary mantle 11.

  Thus, each plasma 18 ejected from the tips of the main torch 1 and the sub-torch 2 is provided so that the central axis of the main torch 1 and the central axis of the sub-torch 2 cross each other. However, since the plasma 18 is conductive, in this state, when the switch unit 9 is closed and the switch unit 15 and the switch unit 34 are opened at the same time, the tip of the main cathode 3 reaches the anode point of the auxiliary mantle 11. A conductive path is formed by the hairpin-shaped plasma 18.

  At this time, the thermal spray material 20 conveyed by the material feeding pipe 19 on the connecting pipe 26 is fed into the high-temperature plasma 18 in a direction crossing the plasma 18 axis. Therefore, the thermal spray material 20 becomes molten particles 21 due to the heat of the plasma 18 and proceeds toward the base material 25 without spreading so much while being accompanied by the plasma flame 23.

  In the plasma flame 23 containing the molten particles 21, only the plasma 18 is separated by the plasma separation means 22 provided on the connecting pipe 26 immediately before the base material 25 in order to reduce the thermal load on the base material 25. Immediately thereafter, the molten particles 21 collide with the base material 25 to form a sprayed coating 24.

  In the above description, the inner surfaces of the main mantle jacket 4, the main second mantle 31 and the sub mantle 11 and the sub second mantle 36 are usually of a double structure, and the inside is cooled by circulation of water or the like. This is omitted and not shown. In the following description, each corresponding cooling system is omitted.

The conventional example has the following problems.
(1) The auxiliary torch has at least two chambers, a chamber that protects the cathode (sub-cladding) and a chamber that protects the anode (sub-cladding), which has many parts, is expensive, and is easy to maintain and inspect. Not.

(2) The cathode part of the auxiliary torch is used when plasma is activated, but becomes an unnecessary part during operation.
(3) The plasma and plasma flame of the main torch bend with time due to the influence of the magnetic field due to the plasma from the sub-torch and the hairpin-shaped plasma. For this reason, the straightness and stability of the plasma and the plasma flame are impaired, resulting in a decrease in plasma output.

  In view of the above circumstances, an object of the present invention is to reduce the number of parts of the sub-torch to reduce the cost, and to simplify and reduce the size of the sub-torch as a whole. Another object is to improve the straightness and stability of plasma and plasma flame and increase the plasma output.

  The present invention provides a composite torch-type plasma generator comprising a main torch and a sub-torch having a cathode and an anode and a plasma gas supply means, wherein a plurality of sub-torches are provided on the radiation centering on the main torch axis. In addition, the anode of each of the sub-torches is surrounded by a mantle, and a cathode is provided on the inner wall of the mantle.

  A narrowing opening is provided at the tip of the auxiliary mantle of the present invention, and the cathode is provided on the inner wall of the narrowing opening. The material of the jacket of the present invention is a material having a thermal conductivity of 330 kcal / mh ° C. or more. The main torch and the sub torch according to the present invention are characterized in that they are provided with swirl flow-in means for swirling all plasma gases to be used.

  An active gas can be used as the plasma gas by providing an independent chamber having no electrode in the main torch or the sub torch of the present invention. The cathode of the auxiliary torch according to the present invention is formed by attaching tungsten or spraying tungsten.

  In the present invention, the anode of the sub-torch is surrounded by a jacket, and the cathode is provided on the inner wall of the jacket, so that the tungsten cathode portion provided in front of the anode is unnecessary in the sub-torch of the conventional composite torch type plasma generator. In addition, an insulating portion and wiring / piping having a protective gas feeding means located between the anodes associated therewith are not required, so that not only can the number of parts be reduced and the cost can be reduced, but also the entire sub-torch is simplified. It has become smaller and easier to maintain and inspect.

  In the present invention, since a plurality of the sub torches are provided on the radiation centering on the main torch axis, the straightness and stability of the plasma and the plasma flame are improved, resulting in an increase in plasma output. It has become possible.

A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a main part of a general-purpose composite torch type plasma spraying apparatus using a plurality of sub-torches, for example, two sub-torches.

  In FIG. 1, reference numeral 3 denotes a main cathode, which is held concentrically by a main mantle 4 having an emission port on the central axis of the main cathode 3 and an insulator 27 having a swirling gas forming means 52. In the swirling gas forming means 52, as shown in FIG. 2, the main plasma gas 6 is first fed into the gas annular chamber 53 from the plasma gas inlet 5, and is arranged in one swirling flow forming hole 54 or equally. Through the plurality of swirling flow forming holes 54, the inner wall 55 of the insulator 27 is swirled as indicated by an arrow 54.

  The negative terminal of the main power supply 7 is connected to the main cathode 3, and the positive terminal of the main power supply 7 is connected to the main jacket 4 via the switch means 8, and these constitute the main torch 1 as a whole. Yes.

  Next, there is a sub-torch anode 10A disposed so as to intersect with the central axis of the main torch 1, that is, the central axis of the main cathode 3, and the sub-torch anode 10A surrounds the sub-torch anode 10A and has a discharge port at the tip. The outer casing 11 and the insulator 28 having the swirl gas forming means 52 similar to the insulator 27 of the main torch 1 are held concentrically. The discharge port of the auxiliary mantle is formed in a nozzle-like constriction port.

  The positive terminal of the second power source 42 is connected to the positive terminal of the auxiliary torch anode 10A via the switch means 47, and the negative terminal of the second power source 42 is connected to the auxiliary mantle 11 via the switch means 48. These constitute the auxiliary torch 2 as a whole.

  A second auxiliary torch 39 of the same type is provided at a position facing the auxiliary torch 2. Similar to the sub torch 2, the second sub torch 39 surrounds the second sub torch anode 40 and has a second sub jacket 41 having a discharge port at the tip, and a swirl flow similar to the insulator 27 of the main torch 1. It is held concentrically by an insulator 49 having gas forming means 52.

  The positive terminal of the second power source 42 is connected to the positive terminal of the second secondary torch anode 40 via the switch means 43, and the negative terminal of the second power source 42 is connected to the second secondary torch anode 40 via the switch means 44. These are connected to the outer sleeve 41, and these constitute a second auxiliary torch 39 as a whole.

  The chambers (sub jackets 11 and 41) for protecting the anodes 10A and 40 of the auxiliary torches 2 and 39 are formed of a heat transfer member having a cooling structure capable of withstanding plasma radiation while maintaining insulation from the anodes 10A and 40. Has been. As this member, a material having a thermal conductivity of 330 kcal / mh ° C. or more is preferable, and for example, W, Cu, Ag, Au, Pt or the like is used.

  The surface of the auxiliary mantle 11 and 41 is surface-treated so that the plasma arc is difficult to contact and the thermal spray material does not adhere. For example, the surface roughness is Ra 0.8 or less, but Ra0. 25 or less is preferable.

  The cathode is provided on the mantles 11 and 41, and the arrangement position thereof is provided, for example, on the inner wall of the mantle or the inner wall of the discharge port (constriction port) at the tip of the mantle.

  Since the cathode emits thermoelectrons, the cathode spot reaches 3000 ° C. or more, and the outer jackets 11 and 41 made of copper or the like naturally melt and vaporize, but the damage at this time is suppressed as much as possible. Therefore, in the present invention, the plasma can be formed only for a short time until the hairpin arc plasma is formed with a current load of 20 to 30 A.

  Most of the sub-coats are made of copper, which is optimal for cost and workability. However, in the atmosphere, patina is generated, which causes contamination in the sprayed coating. It is desirable.

  For example, tungsten is used as the material of the cathode provided in the jacket, but it is technically difficult and costly to manufacture the cathode entirely from tungsten because the material is hard and brittle. It is preferable to form the cathode by attaching the tungsten only to the portion to be formed or by spraying tungsten (coating).

  The main torch 1, the sub torch 2 and the second sub torch 39 are fixed by the connecting pipe 26, and each has a structure that can be easily detached and kept insulative.

  In FIG. 1, an inert gas such as argon is flowed from the main plasma gas inlet 5 as the main plasma gas 6, the switch means 8 and the switch means 46 are opened, the switch means 8 is closed, and the main power supply 7 is turned on. When a high frequency is applied between the main cathode 3 and the main mantle 4, a main starting arc 16 is formed from the tip of the main cathode 3 toward the outlet of the main mantle 4, thereby heating the main plasma gas 6, and plasma 18 is discharged from the front end of the main mantle 4 toward the outside of the main torch 1.

  Next, with the switch means 43 and the switch means 44 open, the switch means 47 and the switch means 48 are closed and applied between the auxiliary torch anode 10A and the auxiliary mantle 11 by the high frequency of the second power source 42, and When an inert gas such as argon is sent as the secondary gas 13 from the secondary gas inlet 12, the secondary starting arc 17 is generated, and the plasma 18 is ejected from the discharge port at the tip of the secondary mantle 11.

  Thus, each plasma 18 ejected from the tips of the main torch 1 and the sub-torch 2 is provided so that the central axis of the main torch 1 and the central axis of the sub-torch 2 cross each other. The crossing points are, for example, 12 mm to 15 mm from the tip of the main mantle 4 of the main torch 1 and 5 mm to 8 mm from the tip of the sub mantle 11 of the sub torch 2. Since the plasma 18 is conductive, in this state, when the switch means 45 is closed and the switch means 8 is opened at the same time, and the switch means 47 and the switch means 48 are opened, the main cathode starts from the tip of the auxiliary torch anode 10A. A conductive path is formed by the hairpin-shaped plasma 18 that reaches the cathode point 3.

  Immediately after that, an inert gas such as argon is flowed as the second auxiliary gas 51 from the second auxiliary gas inlet 50 to apply the plasma 18 of the second auxiliary torch 39, and the switch means 45 and the switch means 48 are opened. Thus, the switch means 43 and the switch means 44 are closed and applied between the second sub torch anode 40 and the second sub jacket 41 by the high frequency of the second power source 42.

  Then, a second secondary starting arc 58 is formed from the tip of the second secondary torch anode 40 toward the discharge port of the second secondary jacket 41, whereby the secondary second gas 51 is heated and the second secondary jacket 41 is heated. Plasma 18 is ejected from the discharge port at the tip.

  The tip of the plasma 18 intersects with the hairpin-shaped plasma 18 extending from the tip of the second auxiliary torch anode 40 to the cathode point of the main cathode 3. Since this plasma 18 is conductive, in this state, the switching means When 45 is closed and the switch means 44 is opened, a T-shaped plasma 18 is formed as a whole from the tip of the second auxiliary torch anode 40 to the main cathode 3.

  By this thermal spray material supply means, any high melting point thermal spray material 20 is immediately heated to a high temperature by a plasma 18 at around 10,000 ° C. and melted. The process proceeds toward the base material 25.

  In the plasma flame 23 containing the molten particles 21, only the plasma 18 is separated by the plasma separation means 22 provided on the connecting pipe 26 immediately before the base material 25 in order to reduce the thermal load on the base material 25. Immediately thereafter, the molten particles 21 collide with the base material 25 to form a sprayed coating 24.

  By providing at least two compatible sub-torches of the present invention symmetrically so as to intersect with the main torch axis, the straightness and stability of the plasma are remarkably improved, and as a result, the high to 100 kW or higher Thermal spraying is possible at the output, and of course the increase in the amount of thermal spraying has enabled the formation of a dense and high quality thermal spray coating that has never been seen before.

A second embodiment of the present invention will be described with reference to FIG.
FIG. 3 shows a composite torch type plasma in which a chamber having no electrode is provided in the main torch 1 as one means that can use not only an inert gas but also an active gas such as air as a plasma gas. The main part of the thermal spraying device is illustrated.

  In FIG. 3, the main cathode 3 is concentrically formed by a main mantle 4 and a main second mantle 31 having an emission port on the axis of the main cathode 3, and an insulator 27 and an insulator 29 having swirl gas forming means 52. In the swirling flow gas forming means, as shown in FIG. 2, the main plasma gas 6 is first fed into the gas annular chamber 53 from the main plasma gas inlet 5, and the swirling flow forming hole 54 or Through a plurality of swirl flow forming holes 54 that are equally arranged, the material is fed as shown by an arrow 54 so as to swivel the inner wall 55 of the insulator 27.

  Similarly, the main second gas 33 is also fed through the main second gas inlet 32 to swivel the inner wall of the insulator 29. The negative terminal of the main power source 7 is connected to the main cathode 3, and the positive terminal of the main power source 7 is connected to the main mantle 4 via the switch means 8 and to the main second mantle 31 via the switch means 34. These constitute the main torch 1 as a whole.

  Next, there is a sub-torch anode 10A disposed so as to intersect with the central axis of the main torch 1, that is, the central axis of the main cathode 3, and the sub-torch anode 10A surrounds the sub-torch anode 10A and has a discharge port at the tip. The outer casing 11 and the insulator 28 having the swirl gas forming means 52 similar to the insulator 27 of the main torch 1 are held concentrically.

  The positive terminal of the second power source 42 is connected to the positive terminal of the auxiliary torch anode 10A via the switch means 47, and the negative terminal of the second power source 42 is connected to the auxiliary mantle 11 via the switch means 48. These constitute the auxiliary torch 2 as a whole.

  A second auxiliary torch 39 of the same type is provided at a position facing the auxiliary torch 2. Similar to the sub torch 2, the second sub torch 39 surrounds the second sub torch anode 40 and has a second sub jacket 41 having a discharge port at the tip, and a swirl flow similar to the insulator 27 of the main torch 1. It is held concentrically by an insulator 49 having gas forming means 52.

  The positive terminal of the second power source 42 is connected to the positive terminal of the sub torch anode 40 via the switch means 43, and the negative terminal of the second power source 42 is connected to the second sub jacket 41 via the switch means 44. These are connected to each other and constitute a sub torch 39 as a whole.

  The main torch 1, the sub torch 2 and the second sub torch 39 are fixed by the connecting pipe 26, and each has a structure that can be easily detached and kept insulative.

  In FIG. 3, an inert gas such as argon is flowed from the main plasma gas inlet 5 as the main plasma gas 6, the switch unit 8 and the switch unit 34 are opened, the switch unit 8 is closed, and the main power source 7 is connected. When a high frequency is applied between the main cathode 3 and the main mantle 4, a main starting arc 16 is formed from the tip of the main cathode 3 toward the outlet of the main mantle 4, thereby heating the main plasma gas 6, and plasma 18 is discharged from the tip of the main mantle 4.

  Next, by closing the switch means 34 and opening the switch means 8, the anode point of the plasma 18 is transferred from the main mantle 4 to the main second mantle 31, and from the tip of the main second mantle 31 to the outside of the main torch 1. Is released towards.

  Next, with the switch means 43 and the switch means 44 open, the switch means 47 and the switch means 48 are closed and applied between the auxiliary torch anode 10A and the auxiliary mantle 11 by the high frequency of the second power source 42, and When an inert gas such as argon is sent as the secondary gas 13 from the secondary gas inlet 12, a secondary starting arc 17 is generated, and a plasma 18 is ejected from the discharge port at the tip of the secondary mantle 11.

  Thus, each plasma 18 ejected from the tips of the main torch 1 and the sub-torch 2 is provided so that the central axis of the main torch 1 and the central axis of the sub-torch 2 cross each other. Although the plasma 18 is conductive, in this state, when the switch means 45 is closed and the switch means 34 is opened at the same time, and the switch means 47 and the switch means 48 are opened, the plasma 18 is opened from the tip of the auxiliary torch anode 10A. A conductive path is formed by the hairpin-shaped plasma 18 that reaches the cathode spot of the cathode 3.

  Immediately after that, an inert gas such as argon is flowed as the second auxiliary gas 51 from the second auxiliary gas inlet 50 to apply the plasma 18 of the second auxiliary torch 39, and the switch means 45 and the switch means 48 are opened. Thus, the switch means 43 and the switch means 44 are closed and applied between the second sub torch anode 40 and the second sub jacket 41 by the high frequency of the second power source 42.

  Then, a second secondary starting arc is formed from the tip of the second secondary starting electrode 40 toward the discharge port of the second secondary jacket 41. As a result, the secondary second gas 51 is heated, and the plasma 18 is ejected from the discharge port at the tip of the secondary secondary mantle 41.

  The tip of the plasma 18 intersects with the hairpin-shaped plasma 18 extending from the tip of the second auxiliary torch anode 40 to the cathode point of the main cathode 3. Since this plasma 18 is conductive, in this state, the switching means When 45 is closed and the switch means 44 is opened, a T-shaped plasma 18 is formed as a whole from the tip of the second auxiliary torch anode 40 to the main cathode 3.

  By this thermal spray material supply means, any high melting point thermal spray material 20 is immediately heated to a high temperature by a plasma 18 at around 10,000 ° C. and melted. The process proceeds toward the base material 25.

  In the plasma flame 23 containing the molten particles 21, only the plasma 18 is separated by the plasma separation means 22 provided on the connecting pipe 26 immediately before the base material 25 in order to reduce the thermal load on the base material 25. Immediately thereafter, the molten particles 21 collide with the base material 25 to form a sprayed coating 24.

  In this embodiment, the ratio of the active gas in the whole plasma gas used in this apparatus can be increased by means using an active gas such as air as the plasma gas, and a reducing atmosphere such as ferrite, alumina, titania, etc. Therefore, it is possible to easily form a material film that can exhibit a unique high performance in an oxidizing atmosphere, which is a great feature of the present invention.

It is a longitudinal cross-sectional view which shows the 1st Embodiment of this invention. It is the sectional view on the ab line of FIG. It is a longitudinal cross-sectional view which shows the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view which shows a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main torch 2 Sub torch 3 Main cathode 4 Main mantle 7 Main power supply 10 Sub torch starting electrode 10A Sub torch anode 11 Sub mantle 14 Sub power source 16 Main starting arc 17 Sub starting arc 18 Plasma 23 Plasma flame 31 Main second mantle 35 Main Second starting arc 36 Sub second mantle 39 Second sub torch 40 Second sub torch anode 41 Second sub mantle 42 Second power source 52 Swirl gas forming means

Claims (7)

In a composite torch type plasma generator comprising a main torch and a sub-torch having a cathode and an anode and a plasma gas supply means,
A plurality of the sub-torches are provided on the radiation around the main torch axis;
The anode of each sub-torch is surrounded by a mantle;
A composite torch type plasma generating apparatus, characterized in that a cathode is provided on an inner wall of the jacket.   2. The composite torch type plasma generating apparatus according to claim 1, wherein a constriction opening is provided at a tip of the mantle and the cathode is provided on an inner wall of the constriction opening.   The composite torch type plasma generator according to claim 1 or 2, wherein the material of the jacket is a material having a thermal conductivity of 330 kcal / mh ° C or more.   4. The composite torch type plasma generator according to claim 1, wherein the outer jacket is made of copper and is surface-treated.   5. The combined torch type plasma generation according to claim 1, wherein the main torch and the sub torch are provided with swirl flow feeding means for swirling all plasma gases to be used. apparatus.   The active gas can be used as the plasma gas by providing an independent chamber without an electrode in the main torch or the sub torch, according to claim 1, 2, 3, 4, or 5. Composite torch type plasma generator.   7. The composite torch type plasma generating apparatus according to claim 1, wherein the sub-torch cathode is formed by attaching tungsten or spraying tungsten.

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