JP7090467B2 - Thermal spraying device - Google Patents

Description

The following disclosure relates to a thermal spraying device.

The thermal spraying device transports and supplies the thermal spray material and the working gas to the thermal spray gun, and applies electric power to the thermal spray gun to generate plasma. In the thermal spray gun, the thermal spray material is melted by the heat of the generated plasma, and is sprayed onto the object together with the plasma-generated working gas to form a film. Thermal spraying is a surface modification technique that generates plasma, melts the thermal spray material using the heat of the plasma, and forms a thermal spray coating on the surface of the object by the molten thermal spray material.

Various techniques have been proposed to stabilize the quality of the film formed by plasma spraying. For example, a technique for preventing dew condensation generated by cooling the inside of a thermal spray gun has been proposed (Patent Document 1). Further, a technique for cooling electronic components of a thermal spraying device at low cost has been proposed (Patent Document 2). Further, a technique for preventing deterioration of the quality of the thermal spray coating due to oxidation of the molten thermal spray material has been proposed (Patent Document 3). Further, in order to prevent particles of the thermal spray material from adhering to the inner wall of the injection nozzle, the nozzle is configured by connecting a plurality of ring-shaped parts in a tubular shape, and an annular injection port is formed on the step portion of the inner wall. Has been proposed (Patent Document 4). Similarly, in order to prevent particles of the spraying material from adhering to the inner wall of the injection nozzle, an injection nozzle device having an injection port for injecting a shield gas in a tubular shape on the circumferential inner wall of the injection nozzle has been proposed. (Patent Document 5). Furthermore, in order to prevent the molten particles of the thermal spray material from adhering to the inner wall of the nozzle, a nozzle hole whose inner diameter gradually expands toward the tip of the nozzle is provided, and a shield gas is applied to the inner wall in the circumferential direction of the nozzle hole. A thermal spraying device having an injection port for injection has been proposed (Patent Document 6).

Japanese Unexamined Patent Publication No. 2001-81540 Japanese Unexamined Patent Publication No. 2004-304011 Japanese Unexamined Patent Publication No. 2017-22921 Japanese Patent No. 4268193 Japanese Patent No. 4897001 Japanese Patent No. 5284774 Hajime Yokozawa, "Study on Energy Separation Performance of Vortex Tubes", Nagoya University Book No.806997, February 2, 1980 Hirokazu Kawabata, "Study on Thermal Fluid Characteristics and Flow Control Technology for Cooling High Temperature Turbine Blade Films", 2014 Graduate School of Engineering, Iwate University, Doctoral Dissertation

The present disclosure provides a technique for suppressing the deposition of thermal spray material in a thermal spraying apparatus.

The thermal spraying apparatus according to one aspect of the present disclosure includes a first gas introduction portion and a protective layer forming portion. The first gas introduction unit introduces gas into the outer cylinder accommodating the anode electrode and the cathode electrode. The protective layer forming portion forms a protective layer separated from the plasma jet, which covers the surface of the anode electrode exposed to the space through which the plasma jet passes by the gas introduced from the first gas introduction portion.

According to the present disclosure, it is possible to suppress the deposition of thermal spray material in a thermal spraying device.

FIG. 1A is a schematic front view of the thermal spraying apparatus according to the first embodiment. FIG. 1B is a schematic cross-sectional view of the thermal spraying apparatus according to the first embodiment as viewed along the line AA of FIG. 1A. FIG. 1C is a schematic rear view of the thermal spraying apparatus according to the first embodiment. FIG. 1D is a schematic cross-sectional view of the thermal spraying apparatus according to the first embodiment as viewed along the line BB of FIG. 1A. FIG. 2A is a schematic front view of a protective layer forming portion of the thermal spraying apparatus according to the first embodiment. FIG. 2B is a schematic cross-sectional view of the protective layer forming portion of the thermal spraying apparatus according to the first embodiment as viewed along A'-A'of FIG. 2A. FIG. 3A is a schematic front view of the thermal spraying apparatus according to the second embodiment. FIG. 3B is a schematic cross-sectional view of the thermal spraying apparatus according to the second embodiment as viewed along the line AA of FIG. 3A. FIG. 3C is a schematic rear view of the thermal spraying apparatus according to the second embodiment. FIG. 3D is a diagram for explaining a protective layer forming portion of the thermal spraying device according to the second embodiment. FIG. 4A is a diagram for explaining an example of a protective layer forming portion of the thermal spraying device according to the second embodiment. FIG. 4B is a diagram for further explaining an example of the protective layer forming portion of the thermal spraying device according to the second embodiment. FIG. 5A is a schematic front view of the thermal spraying apparatus according to the third embodiment. FIG. 5B is a schematic cross-sectional view of the thermal spraying apparatus according to the third embodiment as viewed along the line AA of FIG. 5A. FIG. 5C is a schematic rear view of the thermal spraying apparatus according to the third embodiment. FIG. 5D is a diagram for explaining a protective layer forming portion of the thermal spraying device according to the third embodiment.

In one disclosed embodiment, the thermal spraying apparatus comprises a first gas introduction section and a protective layer forming section. The first gas introduction unit introduces gas into the outer cylinder accommodating the anode electrode and the cathode electrode. The protective layer forming portion forms a protective layer separated from the plasma jet, which covers the surface of the anode electrode exposed to the space through which the plasma jet passes by the gas introduced from the first gas introduction portion.

Further, in one of the disclosed embodiments, the protective layer forming portion forms a protective layer including two layers, that is, the gas introduced from the first gas introduction portion and the air existing near the surface of the anode electrode. You may.

Further, in one of the disclosed embodiments, the protective layer forming portion is a swirling rectifying portion that surrounds and fixes the cathode electrode from the surroundings, and the first gas introducing portion is a radial direction with respect to the protective layer forming portion. Gas may be introduced from the outside.

Further, in one disclosed embodiment, the swirling rectifying unit may have a substantially ring shape and may have two or more guide grooves extending radially inward from the outside to the inside.

Further, in one of the disclosed embodiments, the swirling rectifying portion has an outer peripheral portion and an inner peripheral portion having a thickness smaller in the axial direction than the outer peripheral portion, and the guide groove may be formed in the outer peripheral portion.

Further, in one disclosed embodiment, the protective layer forming portion may include a gas passage, a cylindrical portion, and a hole portion. The gas passage is formed in the anode electrode, and gas is introduced from the first gas introduction portion. The cylindrical portion separates the gas passage from the space through which the plasma jet passes. The hole portion is formed in a cylindrical portion and communicates the gas passage and the space through which the plasma jet passes.

Further, in one disclosed embodiment, the hole may be inclined so that the opening on the space side through which the plasma jet passes in the cylindrical portion is located on the downstream side of the plasma jet with respect to the opening on the opposite side. good.

Further, in one disclosed embodiment, the hole portion may be formed so that the central axis of the hole portion deviates from the central direction of the outer cylinder in the tangential direction.

Further, in one disclosed embodiment, the hole portion may have a fan shape extending from the opening on the opposite side toward the opening on the space side through which the plasma jet passes in the cylindrical portion.

Further, the thermal spraying device according to one of the disclosed embodiments may further include a second gas introduction portion for introducing the second gas into a space provided along the outer periphery of the cathode electrode.

Further, in one disclosed embodiment, the protective layer forming portion may include a gas passage and a first porous portion. The gas passage is formed in the anode electrode, and gas is introduced from the first gas introduction portion. The surface of the first porous portion is exposed to the space through which the plasma jet passes, and separates the gas passage from the space through which the plasma jet passes.

Further, in one disclosed embodiment, the first porous portion may be a sintered body of metal or a porous metal.

Further, the thermal spraying apparatus according to one of the disclosed embodiments is arranged around the cathode electrode and has a second porous portion formed of a dielectric material and a second porous portion for introducing gas into the second porous portion. The gas introduction unit of the above may be further provided.

Hereinafter, the disclosed embodiments will be described in detail with reference to the drawings. The present embodiment is not limited. Each embodiment can be appropriately combined as long as the processing contents do not contradict each other.

(First Embodiment)
The thermal spraying device 100A according to the first embodiment is a plasma spraying device, for example, a thermal spraying gun, which generates a plasma jet to form a thermal spray coating on an object. The thermal spray gun includes, for example, an anode electrode and a cathode electrode formed in a cylindrical shape. A working gas and a thermal spraying material are introduced inside the cylinder of the cathode electrode. DC power is applied between the anode electrode and the cathode electrode, and a plasma jet of working gas is generated. The generated plasma jet melts the thermal spray material and adheres to the object to form a thermal spray coating. Hereinafter, the tubular portion through which the generated plasma jet passes is also referred to as a nozzle.

When a plasma jet is generated, the powder of the thermal spray material may adhere to the inner surface of the nozzle due to the influence of the heat of the plasma. The state of the plasma jet generated when the powder of the thermal spray material is deposited changes. In addition, the nozzle may be blocked when the amount of deposit increases.

In this regard, it is conceivable to blow a gas around the cathode electrode and blow the blown gas downstream together with the plasma jet to prevent the accumulation of the thermal spray material around the cathode electrode and downstream. However, it is difficult to protect the entire downstream path by such means because the flow of the blown gas becomes short-circuited. Further, it is conceivable that the temperature of the plasma jet decreases as the gas blown to the cathode electrode and the working gas merge to increase the flow rate. Further, when the gas blown to the cathode electrode and the plasma jet come into contact with each other, it is conceivable that the temperature of the plasma jet becomes non-uniform or the temperature gradient becomes large. On the other hand, when the thermal spraying device has a structure utilizing the ejector effect, a differential pressure is generated between the space on the cathode electrode side and the plasma jet passage. Therefore, the thermal spray material tends to be deposited around the working gas hole of the cathode electrode.

The thermal spraying device 100A according to the first embodiment forms a protective layer that protects the inner surface of the nozzle by generating a swirling flow in the nozzle, and cools the inner surface of the nozzle by the swirling flow. Therefore, the thermal spraying device 100A according to the first embodiment can suppress the accumulation of the thermal spraying material in the thermal spraying device 100A, for example, on the inner wall of the nozzle.

(An example of the configuration of the thermal spraying device 100A according to the first embodiment)
FIG. 1A is a schematic front view of the thermal spraying device 100A according to the first embodiment. FIG. 1A shows a state in which the thermal spraying device 100A is viewed from the outlet side (the side where the plasma jet is ejected). FIG. 1B is a schematic cross-sectional view of the thermal spraying apparatus 100A according to the first embodiment as viewed along AA of FIG. 1A. FIG. 1C is a schematic rear view of the thermal spraying device 100A according to the first embodiment. FIG. 1C shows a state in which the thermal spraying device 100A according to the first embodiment is viewed from the inlet side (the side where the thermal spraying material is introduced). FIG. 1D is a schematic cross-sectional view of the thermal spraying apparatus 100A according to the first embodiment as viewed along the line BB of FIG. 1A.

The thermal spraying device 100A includes an outer cylinder 1, an anode electrode 2, a cathode electrode 3, a cooling mechanism 4, a protective layer forming portion 5, and a first gas introducing portion 6.

The outer cylinder 1 is an outer structural portion of the thermal spraying device 100A. The outer cylinder 1 is formed of an insulator or a dielectric. The outer cylinder 1 has a substantially cylindrical shape. One end of the outer cylinder 1 is an inlet 11 into which the thermal spray material and the working gas are introduced. The other end of the outer cylinder 1 is an outlet 12 from which the plasma jet generated in the thermal spraying device 100A is ejected. The outer cylinder 1 houses the anode electrode 2 and the cathode electrode 3 inside. Further, a part of the flow path through which the cooling medium CM of the cooling mechanism 4 flows is housed inside the outer cylinder 1.

The anode electrode 2 is arranged inside the outer cylinder 1 and in the vicinity of the outlet 12. The anode electrode 2 has a substantially cylindrical shape, and a space S1 through which a plasma jet passes is formed in the center.

The cathode electrode 3 is arranged on the inlet 11 side of the outer cylinder 1 with respect to the anode electrode 2. The cathode electrode 3 has a substantially cylindrical shape, and a space S2 through which the working gas and the thermal spray material pass is formed in the center.

The cooling mechanism 4 cools the anode electrode 2 and the cathode electrode 3 by circulating the cooling medium CM inside the thermal spraying device 100A. In the example of FIG. 1A, a flow path for introducing the cooling medium CM is provided inside the outer cylinder 1, and the cooling medium CM is introduced in the vicinity of the cathode electrode 3. After cooling the cathode electrode 3, the cooling medium CM is routed in the vicinity of the anode electrode 2 and passes around the anode electrode 2 (see FIG. 1D). After that, the cooling medium CM is transferred in the direction opposite to the direction in which it is introduced through the flow path of the cooling mechanism 4. The configuration and arrangement of the cooling mechanism 4 are not particularly limited, and the flow paths may be arranged at different positions as long as the anode electrode 2 and the cathode electrode 3 can be cooled.

The protective layer forming portion 5 forms a protective layer that covers the surface of the anode electrode 2 exposed to the space S1 by the gas introduced from the first gas introducing portion 6. The protective layer is composed of two layers, a gas introduced from the first gas introduction unit 6 and an atmosphere existing near the surface of the anode electrode 2. The protective layer forming portion 5 has a substantially ring shape, and the cathode electrode 3 penetrates the center thereof. The protective layer forming portion 5 is arranged around the cathode electrode 3 so as to surround the cathode electrode 3, and isolates the anode electrode 2 from the cathode electrode 3. The protective layer forming portion 5 is formed of an insulator or a dielectric. The protective layer forming portion 5 is, for example, a ring-shaped swirling straightening vane (swiveling straightening vane) that surrounds and fixes the cathode electrode 3 from the surroundings. The protective layer forming portion 5 rectifies the gas blown from the outer peripheral side to the inner peripheral side of the protective layer forming portion 5 and guides it toward the cathode electrode 3 to generate a swirling flow.

FIG. 2A is a schematic front view of the protective layer forming portion 5 of the thermal spraying device 100A according to the first embodiment. FIG. 2B is a schematic cross-sectional view of the protective layer forming portion 5 of the thermal spraying device 100A according to the first embodiment as viewed along A'-A'of FIG. 2A.

As shown in FIG. 2A, the protective layer forming portion 5 has a guide groove 51, an inner peripheral groove 52, and a flange 53.

A plurality of guide grooves 51 are provided on the outer peripheral portion of the protective layer forming portion 5, and are formed so as to be inclined at the same angle with respect to the radial direction of the protective layer forming portion 5 from the outside to the inside of the protective layer forming portion 5. Will be done. The guide groove 51 is a recess formed by cutting out the surface of the protective layer forming portion 5 on the outlet 12 side. In the example of FIG. 2A, the protective layer forming portion 5 has six guide grooves 51. However, the number of guide grooves 51 is not limited to 6. The guide grooves 51 may be any number of 2 or more. The number of guide grooves 51 is preferably, for example, 3 or more. The guide groove 51 guides the gas blown from the outside to the inside of the protective layer forming portion 5 toward the cathode electrode 3.

The inner peripheral groove 52 is provided in the inner peripheral portion of the protective layer forming portion 5 so as to surround the cathode electrode 3, and has substantially the same thickness as the guide groove 51. The inner peripheral groove 52 guides the gas guided along the guide groove 51 in the direction of swirling around the cathode electrode 3.

The flange 53 is provided on the outermost peripheral portion of the protective layer forming portion 5 and is arranged on the inlet 11 side.

The first gas introduction unit 6 (see FIG. 1D) introduces gas into the outer cylinder 1 accommodating the anode electrode 2 and the cathode electrode 3. The first gas introduction unit 6 introduces gas from the outside of the outer cylinder 1 toward the protective layer forming unit 5. The gas introduced by the first gas introduction unit 6 is hereinafter referred to as a shield gas SG. The first gas introduction unit 6 includes a gas passage 61 that penetrates the outer cylinder 1 and guides the shield gas SG, and a gas supply unit 62 that controls the flow rate of the shield gas SG and supplies the shield gas SG (for example, a mass flow controller, It has an MFC) and a pipe 63 connecting the gas passage 61 and the gas supply unit 62 (see FIG. 1D). The gas passage 61 of the first gas introduction portion 6 penetrates the outer cylinder 1 and reaches the outer periphery of the protective layer forming portion 5. The gas supply unit 62 of the first gas introduction unit 6 supplies a predetermined flow rate of the shield gas SG to the gas passage 61 via the pipe 63. The gas passage 61 guides the shield gas SG toward the outer periphery of the protective layer forming portion 5. The shield gas SG reaches the inner peripheral groove 52 along the guide groove 51 of the protective layer forming portion 5 and forms a swirling flow that swirls around the cathode electrode 3. The formed swirling flow flows from the cathode electrode 3 side to the anode electrode 2 side, and forms a protective layer that swirls on the surface of the anode electrode 2 by centrifugal force. After that, the swirling flow is blown out of the thermal spraying device 100A from the outlet 12.

Although not shown, the thermal spraying device 100A includes means for applying DC power between the anode electrode 2 and the cathode electrode 3 to discharge the electric power.

(Operation of each part during plasma spraying, etc.)
When performing plasma spraying in the thermal spraying device 100A, the working gas and the thermal spraying material are introduced into the space S2 from the inlet 11. Further, cooling by the cooling mechanism 4 and formation of a swirling flow by the shield gas SG introduced from the first gas introduction unit 6 into the protective layer forming unit 5 are executed. Further, DC power is applied between the anode electrode 2 and the cathode electrode 3 to perform discharge. The introduced working gas is turned into plasma by electric discharge. The heat generated by the plasma melts the thermal spray material and a plasma jet is generated. The plasma jet is ejected from the outlet 12 to the object through the space S1. At this time, air in the space S1 exists between the surface of the anode electrode 2 exposed to the space S1 and the swirling flow. The air in the space S1 is pressed against the surface of the anode electrode 2 by the centrifugal force of the swirling flow of the shield gas SG formed by the protective layer forming portion 5, and the protective layer is formed. The protective layer formed at this time includes two layers, an atmospheric layer and a shield gas SG layer.

(Effect of the first embodiment)
As described above, the thermal spraying apparatus according to the first embodiment includes a first gas introduction portion and a protective layer forming portion. The first gas introduction unit introduces gas into the outer cylinder accommodating the anode electrode and the cathode electrode. The protective layer forming portion forms a protective layer separated from the plasma jet by the gas introduced from the first gas introduction portion. The protective layer covers the surface of the anode electrode exposed to the space S1 through which the plasma jet passes. Thereby, the protective layer protects the anode electrode from heat and products generated by the plasma jet generated in the thermal spraying device. The protective layer also acts as a cushioning material between the heat generated by the plasma jet and the product and the anode electrode. The protective layer also has a function of cooling the anode electrode. Therefore, according to the first embodiment, it is possible to suppress the deposition of the thermal spray material in the thermal spraying apparatus. Further, since the protective layer is a swirling flow, it does not mix with the plasma jet flowing near the center of the nozzle of the thermal spraying device and does not obstruct the plasma jet.

Further, in the thermal spraying apparatus according to the first embodiment, the protective layer forming portion is a swirling rectifying portion that surrounds and fixes the cathode electrode from the surroundings, and the first gas introducing portion refers to the protective layer forming portion. Introduce gas from the outside in the radial direction. Therefore, the swirling rectifying unit generates a high-speed swirling flow and swirls the protective layer while pressing it on the surface of the anode electrode by centrifugal force. At this time, the swirling flow also becomes the speed of sound or a high speed close to the speed of sound. Therefore, the thermal spraying device according to the first embodiment can protect the anode electrode from the plasma jet and at the same time cool it by a high-speed swirling flow.

Further, the thermal spraying apparatus according to the first embodiment can clean the oxide film and deposits generated or adhered on the anode electrode and the cathode electrode by the protective layer which is a high-speed swirling flow. For example, in the first embodiment, the blast powder is added to the shield gas SG in a state where no electric power is applied to the anode electrode 2 and the cathode electrode 3, and a swirling flow is formed in the protective layer forming portion 5. Thereby, the surfaces of the anode electrode 2 and the cathode electrode 3 can be cleaned. Further, when cleaning is performed with electric power applied to the anode electrode 2 and the cathode electrode 3, a reactive gas may be added to the shield gas SG instead of the blast powder. Further, a reactive gas may be added to the shield gas SG in addition to the blast powder.

Further, in the thermal spraying apparatus according to the first embodiment, the swirling rectifying portion has a substantially ring shape and has two or more guide grooves extending radially inward from the outside to the inside. Further, the swirl rectifying portion has an outer peripheral portion and an inner peripheral portion having a thickness smaller in the axial direction than the outer peripheral portion, and a guide groove is formed in the outer peripheral portion. Therefore, the thermal spraying apparatus according to the first embodiment can form a protective layer with a simple configuration and suppress the deposition of the thermal spraying material.

(Modification 1: Shape of protective layer forming portion 5)
In the first embodiment, the protective layer forming portion 5 is provided with a guide groove 51 and an inner peripheral groove 52 to generate a swirling flow. Not limited to this, a through hole may be provided instead of the guide groove 51. For example, a plurality of holes extending radially from the outer periphery of the protective layer forming portion 5 are communicated with each other by a ring-shaped hole extending in the axial direction of the protective layer forming portion 5 and opening on the space S1 side to form a through hole. May be formed. The number of holes opened on the outer periphery of the protective layer forming portion 5 is not particularly limited as in the guide groove 51, but it is preferable to provide two or more holes.

(Second embodiment)
Unlike the thermal spraying device 100A according to the first embodiment, the thermal spraying device 100B according to the second embodiment includes a gas passage (gas passage 21, which will be described later) formed inside the anode electrode to allow gas to pass through. The anode electrode of the thermal spraying apparatus 100B according to the second embodiment includes a hole formed inside the anode electrode to allow a gas passage through which the gas passes and a space S1 through which the plasma jet passes. Then, the spraying apparatus 100B according to the second embodiment is in the form of a film by flowing gas from the gas passage formed inside the anode electrode toward the surface of the anode electrode exposed in the space S1 through which the plasma jet passes. Form a laminar flow. In the second embodiment, the protective layer is formed by such a film-like laminar flow.

(An example of the configuration of the thermal spraying device 100B according to the second embodiment)
FIG. 3A is a schematic front view of the thermal spraying device 100B according to the second embodiment. FIG. 3B is a schematic cross-sectional view of the thermal spraying apparatus 100B according to the second embodiment as viewed along AA of FIG. 3A. FIG. 3C is a schematic rear view of the thermal spraying device 100B according to the second embodiment. FIG. 3D is a diagram for explaining the protective layer forming portion 5B of the thermal spraying device 100B according to the second embodiment. The rough configuration of the thermal spraying device 100B according to the second embodiment is the same as that of the thermal spraying device 100A according to the first embodiment. Therefore, the description of the same configuration is omitted, and the same reference numerals are given.

As shown in FIGS. 3A to 3D, the thermal spraying device 100B according to the second embodiment includes an outer cylinder 1B, an anode electrode 2B, a cathode electrode 3B, and a cooling mechanism 4B, similarly to the thermal spraying device 100A. The thermal spraying device 100B further includes a first gas introduction unit 6B (see FIG. 3D), a second gas introduction unit 7B (see FIG. 3D), and a ring 8.

The configuration and material of the outer cylinder 1B are the same as those of the outer cylinder 1 of the thermal spraying device 100A according to the first embodiment. The inlet 11B and the outlet 12B of the outer cylinder 1B are also the same as the inlet 11 and the outlet 12 of the outer cylinder 1 of the thermal spraying device 100A according to the first embodiment.

The anode electrode 2B includes a gas passage 21, a plurality of holes 22, and a cylindrical portion 23. The anode electrode 2B also has a flow path 41B in which the cooling medium CM of the cooling mechanism 4B flows.

The gas passage 21 is formed inside the anode electrode 2B and communicates with the first gas introduction portion 6B. The gas passage 21 is also communicated with the space S1 by a plurality of holes 22 formed in the cylindrical portion 23. The first gas introduction unit 6B introduces the first shield gas SG1 into the gas passage 21.

The plurality of holes 22 are formed in the cylindrical portion 23 and communicate the gas passage 21 with the space S1. The hole 22 may be, for example, circular on the surface of the cylindrical portion 23 on the gas passage 21 side and elliptical on the surface of the cylindrical portion 23 on the space S1 side. Further, the hole portion 22 is formed with an inclination so that the opening on the space S1 side of the cylindrical portion 23 is closer to the outlet 12B than the opening on the opposite side. Further, the hole portion 22 may be formed so that the diameter of the opening on the space S1 side is larger than the diameter of the opening on the opposite side. Further, the hole portion 22 may be formed so as to branch from the middle. For example, in the vicinity of the space S1, the hole portion 22 branches from the middle into a main hole and a sub-hole having a larger radial inclination than the main hole so that the main hole and the opening of the sub-hole have the same size. It may be formed. Further, the hole portion 22 may be formed so that the central axis of the hole portion 22 deviates from the central direction of the outer cylinder 1B in the tangential direction. For example, when the hole portion 22 is projected onto the cross section of the outer cylinder 1B, the hole portion 22 may be formed so as to be inclined with respect to the radial direction of the outer cylinder 1B.

The cylindrical portion 23 is the innermost peripheral portion of the anode electrode 2B whose surface is exposed in the space S1 through which the plasma jet passes. A plurality of holes 22 are formed in the cylindrical portion 23. The cylindrical portion 23 separates the gas passage 21 and the space S1, and communicates the gas passage 21 and the space S1 with a plurality of holes 22.

The anode electrode 2B is a protective layer forming portion 5B that forms a film-like laminar flow covering the surface of the anode electrode 2B exposed to the space S1 as a protective layer by the gas introduced from the first gas introducing portion 6B. .. The protective layer is composed of the gas introduced from the first gas introduction unit 6B.

The configuration of the cathode electrode 3B is substantially the same as that of the cathode electrode 3 of the first embodiment.

The ring 8 is arranged so as to surround the cathode electrode 3B from the outside, and isolates the anode electrode 2B from the cathode electrode 3B. The ring 8 is a ring-shaped member of an insulator or a dielectric. The ring 8 is provided with a space S3 having a predetermined axial width along the surface of the ring 8 on the inlet 11B side of the outer cylinder 1B. Further, between the ring 8 and the cathode electrode 3B, a ring-shaped space S4 having a predetermined radial width is formed around the cathode electrode 3B. Further, a space S5 for communicating the space S4 and the space S1 is provided between the ring 8 and the cathode electrode 3B. The space S5 may be, for example, a through hole formed at an arbitrary position of the ring 8 and communicating the space S4 and the space S1.

The first gas introduction unit 6B has a gas passage 61B that penetrates the outer cylinder 1B and communicates with the gas passage 21 formed in the anode electrode 2B, an MFC that supplies the first shield gas SG1 to the gas passage 61B, and the like. It has a gas supply unit 62B of the above, and a pipe 63B connecting the gas passage 61B and the gas supply unit 62B. The gas supply unit 62B of the first gas introduction unit 6B supplies the first shield gas SG1 at a predetermined flow rate to the gas passage 21 via the pipe 63B. The supplied first shield gas SG1 passes through the hole 22 and forms a protective layer which is a film-like laminar flow on the surface of the anode electrode 2B exposed to the space S1. The flow rate of the first shield gas SG1 is controlled to a flow rate that does not discharge on the surface of the anode electrode 2B. Further, the flow rate of the first shield gas SG1 is controlled so as to seamlessly cover the surface of the anode electrode 2B.

The second gas introduction unit 7B is a gas supply unit that controls the flow rate of the gas passage 71B that guides the second shield gas SG2 and the second shield gas SG2 and supplies the second shield gas SG2 to the gas passage 71B. It has a 72B (for example, MFC) and a pipe 73B that penetrates the outer cylinder 1B and connects the gas passage 71B and the gas supply unit 72B. The gas passage 71B includes a space S3 on the inlet 11B side of the ring 8, and spaces S4 and S5 provided between the ring 8 and the cathode electrode 3B. The gas passage 71B communicates with the space S1 through the spaces S3, S4, and S5. The opening on the space S1 side of the gas passage 71B is arranged at a position where the second shield gas SG2 does not mix with the plasma jet. The second gas introduction unit 7B supplies the second shield gas SG2 having a predetermined flow rate from the gas supply unit 72B to the gas passage 71B via the pipe 73B, and the second shield from the gas passage 71B to the space S1. Introduce gas.

As described above, the thermal spraying apparatus 100B according to the second embodiment includes the anode electrode 2B including the first gas introduction portion 6B and the anode electrode 2B (gas passage 21, hole portion 22, cylindrical portion 23). It is equipped with a mechanism to cool and protect the gas. Further, the thermal spraying device 100B according to the second embodiment includes a mechanism for cooling and protecting the cathode electrode 3B including the second gas introduction unit 7B and the ring 8.

FIG. 3D is a diagram for explaining the protective layer forming portion 5B of the thermal spraying device 100B according to the second embodiment. As shown in FIG. 3D, the first shield gas SG1 introduced into the gas passage 21 by the first gas introduction unit 6B is introduced into the space S1 from the gas passage 21 through the hole portion 22. The first shield gas SG1 introduced into the space S1 forms a film-like laminar flow flowing in the outlet 12B direction depending on the shape and inclination angle of the hole 22. The laminar flow cools and protects the surface of the anode electrode 2B by membrane cooling. On the other hand, the second shield gas SG2 introduced into the gas passage 71B by the second gas introduction unit 7B passes through the spaces S3, S4 and S5 and is introduced into the space S1. While passing through the spaces S3, S4 and S5, the second shield gas SG2 cools the cathode electrode 3B.

4A and 4B are diagrams for explaining an example of the protective layer forming portion 5B of the thermal spraying device 100B according to the second embodiment. FIG. 4A simply shows the arrangement of the holes 22 formed in the anode electrode 2B. Here, the state in which the anode electrode 2B is spread out in a plate shape is shown in the figure. As an example, the size of the anode electrode 2B developed in a plate shape is 19.8 mm (mm) in the axial direction, the tube diameter is φ5 mm, and the peripheral length is 5π (15.7 mm). The plate thickness is 1 mm and the hole diameter is 0.6 mm. Further, the hole portion 22 penetrates the cylindrical portion 23 of the anode electrode at an inclination angle of 30 degrees (FIG. 5B). Assuming that the hole diameter is 0.6 mm = 1D, the spread range of the gas emitted from each hole is the hole spacing of 3D in the peripheral length direction, and the gas flow length is 15D in the pipe length direction. The holes in the first and third rows from the upstream side are arranged based on the spread range and flow length of the gas. Then, the holes in the second and fourth rows from the upstream side are shifted by 1.5D in the circumferential length direction from the holes in the first and third rows, and arranged so that no gas does not flow. In this way, for example, the hole diameter is set to 0.8 mm or less, and a total of 26 holes can be arranged. By arranging the holes 22 in this way, a film-like protective layer can be seamlessly formed on the surface of the anode electrode 2B by the first shield gas SG.

Although it is possible to supply the first shield gas SG1 and the second shield gas SG2 from the same supply unit, in the present embodiment, the shields are shielded from two separate systems from the viewpoint of preventing an electrical short circuit. Supplying gas.

(Effect of the second embodiment)
In the thermal spraying device 100B according to the second embodiment, the protective layer forming portion includes a gas passage, a cylindrical portion, and a hole portion. The gas passage is formed in the anode electrode, and gas is introduced from the first gas introduction portion. The cylindrical portion separates the gas passage from the space through which the plasma jet passes. The hole portion is formed in a cylindrical portion and communicates the gas passage and the space through which the plasma jet passes. Therefore, according to the second embodiment, a film-like laminar flow is formed on the surface of the anode electrode. Therefore, the thermal spraying device can cool and protect the surface of the anode electrode by film cooling. In addition, the deposition of thermal spray material in the thermal spraying device can be suppressed. Further, in the thermal spraying apparatus according to the second embodiment, the protective layer, which is a film-like laminar flow, can prevent the scattered matter from the plasma jet from coming into close contact with the surface of the anode electrode. Further, the protective layer can reduce the deposition of an oxide film or the like on the electrode surface due to the influence of heat due to the plasma jet.

Further, in the second embodiment, the hole portion may be inclined so that the opening portion of the cylindrical portion 23 on the space S1 side is located on the downstream side of the plasma jet with respect to the opening portion on the opposite side. Further, the hole portion may have a shape in which the central axis of the hole portion is deviated from the center direction of the outer cylinder in the tangential direction. For example, the hole may be formed so that the axial direction of the hole is inclined with respect to the radial direction of the outer cylinder when the hole is projected onto the cross section of the outer cylinder. Therefore, the gas introduced into the space through which the plasma jet passes is not introduced in the direction penetrating the plasma jet and does not disturb the flow of the plasma jet. Therefore, the thermal spraying apparatus according to the second embodiment does not lower the temperature of the plasma jet. Further, in the second embodiment, the gas introduced into the space through which the plasma jet passes is not introduced so as to join or mix with the plasma jet. Therefore, the thermal spraying apparatus according to the second embodiment does not lower the temperature of the plasma jet.

Further, in the second embodiment, the hole portion may have a fan shape extending from the opening on the opposite side toward the opening on the space S1 side of the cylindrical portion 23. With this configuration, a film-like protective layer can be seamlessly formed on the surface of the anode electrode of the thermal spraying device.

Further, in the thermal spraying apparatus 100B according to the second embodiment, the protective layer forming portion 5B further introduces a second gas into a space (for example, spaces S4 and S5) provided along the outer periphery of the cathode electrode. A gas introduction unit may be further provided. With this configuration, the thermal spraying device can not only cool and protect the anode electrode, but also cool the cathode electrode.

Further, the thermal spraying device according to the second embodiment may use the protective layer as a cleaning means as in the thermal spraying device according to the first embodiment.

Various methods of cooling the wall surface of the space through which the plasma jet passes by using gas can be considered. For example, there may be a case where the gas is introduced from a direction perpendicular to the axis of the nozzle, or a case where a step is provided on the wall surface of the nozzle and the gas is introduced in the downstream direction from the opening of the step portion. However, when the gas is introduced from the direction perpendicular to the axis of the nozzle, a pair of counterclockwise and clockwise vortices are formed at the gas outlet portion. Then, the vortex forms a velocity component in the direction away from the wall, which hinders the cooling of the wall. Even if a step is provided on the wall surface, the direction of the introduced gas is substantially the same as the direction of the flow of the plasma jet and does not diffuse, so that the cooling efficiency is lowered. In consideration of the above, it is preferable that the shape of the hole 22 of the thermal spraying device 100B according to the second embodiment is in a direction inclined with respect to the axial direction as described above.

(Modification example)
In the second embodiment, the ring 8 is a ring-shaped member, and a predetermined space S3 to S5 is provided between the ring 8 and the cathode electrode 3B. Not limited to this, the ring 8 may have a shape in which a plurality of rings forming concentric layers are stacked, and the second shield gas SG2 may be introduced from the boundary of each layer.

(Third embodiment)
The thermal spraying device 100C according to the third embodiment includes an anode electrode whose portion exposed on the space side through which the plasma jet passes is made of a porous material. Then, the thermal spraying device 100C exudes a shield gas from the surface of the porous anode electrode and forms a protective layer by a film of the exuded gas to suppress the deposition of the thermal spray material. Further, the thermal spraying device 100C according to the third embodiment efficiently cools the anode electrode by exuding the shield gas through the porous anode electrode.

FIG. 5A is a schematic front view of the thermal spraying device 100C according to the third embodiment. FIG. 5B is a schematic cross-sectional view of the thermal spraying apparatus 100C according to the third embodiment as viewed along AA of FIG. 5A. FIG. 5C is a schematic rear view of the thermal spraying device 100C according to the third embodiment. FIG. 5D is a diagram for explaining the protective layer forming portion 5C of the thermal spraying device 100C according to the third embodiment. The rough configuration of the thermal spraying device 100C according to the third embodiment is the same as that of the thermal spraying devices 100A and 100B according to the first and second embodiments. Therefore, the description of the same configuration is omitted, and the same reference numerals are given.

As shown in FIGS. 5A to 5D, the thermal spraying device 100C according to the third embodiment includes an outer cylinder 1C, an anode electrode 2C, a cathode electrode 3C, and a cooling mechanism 4C, similarly to the thermal spraying devices 100A and 100B. The thermal spraying device 100C further includes a first gas introduction section 6C (see FIG. 5D), a second gas introduction section 7C (see FIG. 5D), and a ring 8C (hereinafter, also referred to as a second porous section). , Equipped with.

The configuration and material of the outer cylinder 1C are the same as those of the outer cylinder 1B of the thermal spraying device 100B according to the second embodiment. The inlet 11C and the outlet 12C of the outer cylinder 1C are also the same as the inlet 11B and the outlet 12B of the outer cylinder 1B of the thermal spraying device 100B according to the second embodiment.

The anode electrode 2C has a gas passage 24 formed inside the anode electrode 2C and communicating with the first gas introduction portion 6C, and a porous portion 25 (the first) having a surface exposed to the space S1 and separating the gas passage 24 and the space S1. 1) and. In the anode electrode 2C, a flow path 41C through which the cooling medium CM of the cooling mechanism 4C flows is formed inside.

The gas passage 24 is a space formed inside the anode electrode 2C. The first shield gas SG1 is introduced into the gas passage 24 from the first gas introduction unit 6C.

The porous portion 25 is a cylindrical member that separates the space S1 from the gas passage 24. The porous portion 25 is formed of a metal sintered body, a porous metal, a bulk material obtained by solidifying a metal wire, or a compression-shaped metal fiber. The porous portion 25 has a plurality of fine ventilation holes or ventilation paths.

The anode electrode 2C is a protective layer forming portion 5C that forms a protective layer covering the surface of the anode electrode 2C exposed to the space S1 by the gas introduced from the first gas introducing portion 6C described later. The protective layer is composed of the gas introduced from the first gas introduction unit 6C.

The cathode electrode 3C is the same as the cathode electrode 3 of the first embodiment.

The cooling mechanism 4C is the same as the cooling mechanism 4B of the second embodiment.

The first gas introduction unit 6C supplies a gas passage 61C that penetrates the outer cylinder 1C and communicates with the gas passage 24 formed in the anode electrode 2C, and a gas supply that supplies the first shield gas SG1 to the gas passage 61C. It has a section 62C (for example, MFC) and a pipe 63C connecting the gas passage 61C and the gas supply section 62C. The gas supply unit 62C of the first gas introduction unit 6C supplies the first shield gas SG1 at a predetermined flow rate to the gas passage 61C via the pipe 63C. The gas passage 61C guides the first shield gas SG1 toward the gas passage 24. The first shield gas SG1 forms a film-like protective layer on the surface of the anode electrode 2C from the gas passage 24 through the porous portion 25.

The second gas introduction unit 7C includes a gas passage 71C formed along the outer periphery of the ring 8C, a gas supply unit 72C (for example, MFC) that supplies the second shield gas SG2 to the gas passage 71C, and an outer cylinder 1C. It has a pipe 73C which penetrates the gas passage 71C and connects the gas passage 71C and the gas supply unit 72C. The gas supply unit 72C of the second gas introduction unit 7C supplies the second shield gas SG2 at a predetermined flow rate to the gas passage 71C via the pipe 73C. The supplied second shield gas SG2 seeps into the ring 8C from the gas passage 71C, is introduced around the cathode electrode 3C, and flows into the space S1.

The ring 8C is a ring-shaped member of a porous material formed of an insulating or dielectric material. The shape of the ring 8C has a shape that matches the outer peripheral shape of the cathode electrode 3C. The ring 8C has, inside, a plurality of fine vents or vents through which gas can pass. Further, the ring 8C may be formed of a dense member. When the ring 8C is formed of a dense member, for example, a through hole for communicating the gas passage 71C and the space S1 is provided inside the ring 8C. Then, the surface of the ring 8C facing the space S1 is covered in a film shape with a porous insulator or dielectric material. As long as the gas passage 71C of the second gas introduction portion 7C and the space S1 can be communicated with each other, the arrangement location of the dense member and the porous material in the ring 8C is not particularly limited.

As described above, the thermal spraying apparatus 100C according to the third embodiment cools and protects the anode electrode including the first gas introduction portion 6C and the anode electrode 2C (gas passage 24, porous portion 25). Equipped with a mechanism. Further, the thermal spraying device 100C according to the third embodiment includes a mechanism for cooling and protecting the cathode electrode 3C, which includes a second gas introduction unit 7C and a porous ring 8C.

FIG. 5D is a diagram for explaining the protective layer forming portion 5C of the thermal spraying device 100C according to the third embodiment. As shown in FIG. 5D, the first shield gas SG1 introduced into the gas passage 24 by the first gas introduction unit 6C is introduced into the space S1 from the gas passage 24 through the porous portion 25. The first shield gas SG1 introduced into the space S1 forms a protective layer film covering the surface of the anode electrode 2C so as to seep out from the surface of the porous portion 25. The protective layer cools and protects the surface of the anode electrode 2C by transpilation cooling. On the other hand, the second shield gas SG2 introduced into the gas passage 71C formed along the outer periphery of the ring 8C (second porous portion) by the second gas introduction portion 7C is formed inside the ring 8C. It is introduced into the space S1 through a plurality of ventilation holes or ventilation paths. While passing through the ring 8C from the gas passage 71C, the second shield gas SG2 cools the outer periphery of the cathode electrode 3C. The flow rates of the first shield gas SG1 and the second shield gas SG2 are set to a level that does not accelerate the plasma jet or penetrate the plasma jet. Further, the flow rate of the first shield gas SG1 is controlled to a flow rate that does not discharge on the anode electrode 2C at the time of discharge.

(Effect of the third embodiment)
In the thermal spraying device 100C according to the third embodiment, the protective layer forming portion 5C includes a gas passage 24 and a first porous portion 25. The gas passage 24 is formed in the anode electrode 2C, and gas is introduced from the first gas introduction unit 6C. The first porous portion 25 separates the gas passage 24 from the space S1, and its surface is exposed to the space S1 through which the plasma jet passes. In this way, by providing the anode electrode 2C with the first porous portion 25 and allowing gas to pass through the porous portion 25, a protective layer covering the surface of the anode electrode 2C so as to exude from the surface of the porous portion 25. Form a film of. Therefore, the thermal spraying device 100C according to the third embodiment can protect the anode electrode 2C and suppress the deposition of the thermal spraying material. Further, since the gas is introduced into the space S1 so as to exude from the anode electrode 2C, it does not interfere with the plasma jet. Further, since the gas is not introduced so as to penetrate the plasma jet, the flow of the plasma jet is not disturbed. Also, since the gas is not introduced to join or mix with the plasma jet, it does not lower the temperature of the plasma jet. Further, since the gas passes through the porous portion 25 and is introduced into the space S1 from the entire surface of the anode electrode 2C, the flow rate of the gas can be reduced.

Further, in the thermal spraying apparatus 100C according to the third embodiment, the first porous portion 25 may be a sintered metal or a porous metal. Therefore, as the first porous portion 25, a porous material suitable for the material of each portion in the plasma jet path can be selected. For example, a conductor, an insulator, a dielectric and the like can be appropriately selected.

Further, the thermal spraying device 100C according to the third embodiment may further include a second porous portion 8C which is arranged around the cathode electrode 3C and is formed of a dielectric material. Further, the thermal spraying device 100C may include a second gas introduction unit 7C for introducing gas into the second porous portion 8C. Therefore, the thermal spraying device 100C according to the third embodiment can cool and protect the cathode electrode 3C by the gas passing through the second porous portion 8C. Further, the gas is introduced into the space S1 so as to permeate through the second porous portion 8C and exude. Therefore, the gas does not interfere with the plasma jet. Further, when the gas is introduced into the space S1 through the second porous portion 8C, it is not introduced in the direction and the flow rate through the plasma jet. Therefore, the gas does not disturb the flow of the plasma jet. Further, when the gas is introduced into the space S1 through the second porous portion 8C, it is not introduced so as to join or mix with the plasma jet. Therefore, the gas does not lower the temperature of the plasma jet. Further, since the gas permeates through the second porous portion 8C and is introduced into the space S1 from the entire surface of the second porous portion 8C, the flow rate of the gas can be reduced.

The materials of the first porous portion 25 and the second porous portion 8C are not particularly limited as long as they can realize transpilation cooling. Therefore, an appropriate porous material can be selected according to the material of each member in the plasma jet path. For example, when a porous membrane is used as the first porous portion 25 and the second porous portion 8C, a material can be selected from a conductor, an insulator, a dielectric, and the like. When the first porous portion 25 and the second porous portion 8C have a structure in which the base material is covered with a porous film, the porous film arranged on the surface is peeled off to regenerate the base material. It may be processed and reused.

Further, the surface of each member may be cleaned by adding a reactive gas to the gas (first and second shielded gases SG1 and SG2) introduced into the thermal spraying device 100C.

(Modification example: material of anode electrode 2C, ring 8C, etc.)
In addition to the examples described above, the configuration of the anode electrode 2C can be variously modified. For example, the anode electrode 2C may be composed of a metal and a sintered metal. In this case, the flow rate of the first shield gas SG1 exuding from the anode electrode 2C into the space S1 can be adjusted by the size of the metal sphere of the sintered metal.

Further, for example, the anode electrode 2C may be made of metal and wire mesh. In this case, the flow rate of the first shield gas SG1 exuding from the anode electrode 2C into the space S1 can be adjusted by adjusting the wire diameter, density, and the like of the wire mesh.

Further, for example, the anode electrode 2C may be made of metal, a through hole for communicating the gas passage 24 provided inside and the space S1 may be formed, and the through hole may be covered with a film-shaped sintered metal material. .. Further, the through holes may be covered with a porous film formed of a conductive material. Further, the through holes may be covered with a porous film formed of an insulator or a dielectric material. When the anode electrode 2C is covered with an insulator or a dielectric film, the portion facing the cathode electrode 3C may be formed so as not to be covered with the film. When the anode electrode 2C is covered with an insulator or a dielectric film, the film thickness is adjusted so that the plasma ignition performance can be maintained.

The shape of the thermal spraying device is not limited to the example described in the above embodiment. For example, even when the introduction position of the thermal spray material or the working gas is different from that of the above embodiment, the protective layer forming portion can be used. That is, by arranging the protective layer forming portion so as to form the protective layer in the nozzle portion through which the thermal spray jet passes, the effect of the above embodiment can be obtained regardless of the structural details of the thermal spraying device.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The above embodiments may be omitted, replaced or modified in various forms without departing from the scope of the appended claims and their gist.

1,1B, 1C Outer cylinder 2,2B, 2C Anode electrode 21 Gas passage 22 Hole part 23 Cylindrical part 24 Gas passage 25 Porous part 3,3B, 3C Cathode electrode 5,5B, 5C Protective layer forming part 51 Guide groove 52 Inner peripheral groove 53 Flange 6, 6B, 6C First gas introduction part 61, 61B, 61C Gas passage 62, 62B, 62C Gas supply part 63, 63B, 63C Pipe 7B, 7C Second gas introduction part 71B, 71C Gas passage 72B, 72C Gas supply unit 73B, 73C Piping 8,8C ring
100A, 100B, 100C Thermal spraying device CM Cooling medium SG Shield gas

Claims (3)

A first gas introduction unit that introduces gas inside the outer cylinder that houses the anode electrode and the cathode electrode, and
A protective layer forming portion that covers the surface of the anode electrode exposed to the space through which the plasma jet passes by the gas introduced from the first gas introducing portion and forms a protective layer separated from the plasma jet.
Equipped with
The protective layer forming portion is
It is a swirling rectifying unit that surrounds and fixes the cathode electrode from the surroundings.
The first gas introduction portion introduces gas toward the cathode electrode from the outer side to the inner side in the radial direction with respect to the protective layer forming portion.
The swirling rectifying unit has a substantially ring shape, and is a thermal spraying device having two or more guide grooves extending radially inward from the outside . The first aspect of the present invention, wherein the protective layer forming portion forms the protective layer including two layers of a gas introduced from the first gas introduction portion and air existing near the surface of the anode electrode. Thermal spraying device. The swirling rectifying portion has an outer peripheral portion and an inner peripheral portion having a thickness smaller in the axial direction than the outer peripheral portion.
The thermal spraying device according to claim 1 , wherein the guide groove is formed on the outer peripheral portion.

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