JP4250927B2 - Thermal spraying apparatus and method of using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal spraying apparatus for forming a coating film by spraying a powder to be processed in a molten or semi-molten state by supplying a powder of a thermal spraying raw material from a spray port of a powder supply pipe to a heat source of a thermal spray gun. Regarding usage.
[0002]
[Prior art]
Spraying is a type of coating technique in which a material is melted or semi-molten with a heat source and sprayed onto a substrate to form a film. Any material that can form this film, such as metal, ceramics, plastic, etc., that does not evaporate or decompose with a heat source, is the target. A combustion flame, arc, plasma, laser, or the like is used as the heat source.
[0003]
When an inert gas is caused to flow between the electrodes and discharged, the inert gas is ionized to form high-temperature and high-speed plasma. A thermal spraying method using this plasma as a heat source is plasma spraying. In general, a water-cooled nozzle-like copper anode and tungsten cathode are used using argon as a working gas. When an arc is generated between these electrodes, the working gas is turned into plasma by the arc and ejected from the nozzle as a high-temperature and high-speed plasma jet. Thermal spray material powder is charged into this plasma jet, heated and accelerated, and sprayed onto the substrate. In flame spraying using a combustion flame, the theoretical maximum temperature of the spray flame is about 3000 ° C. On the other hand, in plasma spraying, since there is no theoretical upper limit on the plasma gas temperature, thermal plasma of about 5000 to 10,000 ° C. is usually used, which is suitable for thermal spraying of high melting point materials.
[0004]
Among plasma spraying apparatuses, there is known an external supply method in which powder of a thermal spraying raw material is supplied from the outside of a thermal spraying gun, in which a thermal spraying gun and a powder tank are separated. FIG. 7 is a cross-sectional view showing an outline of this type of conventional plasma spraying apparatus. Hereinafter, description will be given based on this drawing.
[0005]
A conventional plasma spraying apparatus 70 includes a spray gun 71, a powder supply pipe 81, a supply hose 82, a powder tank 83, and the like. A nozzle 74 is provided at the tip of the spray gun 71, and a rod-like cathode 72 and a nozzle-like anode 73 are provided on the nozzle 74. When the working gas 75 is introduced into the nozzle 74 and an arc is generated between the cathode 72 and the anode 73, the working gas 75 is turned into plasma, and a high-temperature and high-speed plasma jet 76 is ejected from the nozzle 74. By supplying a powder 84 of a thermal spray material to the plasma jet 76, the powder 84 is melted and sprayed onto an object to be processed (not shown) to form a film. On the outside of the plasma jet 76, a thermal spraying frame 77 made of powder 84 in the form of droplets is formed.
[0006]
In this type of plasma spraying apparatus 70, the spray gun 71 and the powder tank 83 are separated from each other, so that the powder tank 83 can be easily enlarged. Therefore, it is advantageous in terms of continuity and stability for large-scale continuous processing production. Moreover, since the thermal spray gun 71 and the powder tank 83 are separate bodies in the plasma spraying apparatus 70, a supply hose 82 for connecting them is necessary. A powder supply gas (not shown) is caused to flow from the powder tank 83 into the supply hose 82, and the powder 84 is placed on this gas flow and supplied to the spray gun 71.
[0007]
The supply hose 82 is flexible so that the spray gun 71 can move freely with respect to the fixed powder tank 84. Further, the supply hose 82 needs a certain length in consideration of the handling of the thermal spray gun 71, and 2.4 m and 3.7 m are commercially available.
[0008]
[Problems to be solved by the invention]
FIG. 8 is a schematic diagram showing how to use the plasma spraying apparatus 70 of FIG. 7, and the process proceeds in the order of FIG. 8 [1] to FIG. 8 [3]. Hereinafter, description will be given based on this drawing. However, the same parts as those in FIG.
[0009]
A powder supply gas 90 is supplied into the supply hose 82, and the powder 84 is placed on the flow of the powder supply gas 90 and supplied to the spray gun 71. The thermal spray gun 71 melts and sprays the powder 84 on the workpiece 91 while facing and moving the workpiece 91 to form a coating 92 (FIGS. 8 [1] and [2]). Then, in order to surely form the coating 92 on the surface end 93 to be processed, the supply of the powder 84 is stopped after the sprayed frame 77 has surely passed the end 93 of the surface to be processed ([3] in FIG. 8). ]).
[0010]
If the powder 84 and the powder supply gas 90 are stopped at the same time when the powder supply is stopped, the powder 84 remains in the supply hose 82, which may cause clogging of the powder in the supply hose 82. If powder clogging occurs, it will interfere with restarting the powder supply. Therefore, only the supply of the powder 84 to the supply hose 82 is stopped and the powder supply gas 90 is kept flowing, so that the powder 84 does not remain in the supply hose 82.
[0011]
However, in this method, even after the formation of the film 92 is completed, the powder 84 remaining in the supply hose 82 enters the plasma jet 76 from the powder supply pipe 81 and melts. Therefore, even after the tip of the spray gun 71 passes through the surface end portion 93 to be processed, the droplet continues to be generated, so that the droplet adheres to peripheral devices including the spray device 70. Since there are many operating parts in the peripheral device, the deposition of droplets on the operating part hinders the operation of the peripheral device. Even when a droplet adheres to a portion other than the operating portion, if it adheres to the peripheral device in the state of the droplet, the labor required for the removal becomes enormous.
[0012]
On the other hand, after the formation of the film 92 is completed, there is also a method of stopping the plasma jet 76 in order not to make the powder 84 into droplets. However, repeated turning on and off of the heat source is not an effective method because it significantly reduces the electrode life of the spray gun 71 and hinders continuous operation.
[0013]
OBJECT OF THE INVENTION
Therefore, a main object of the present invention is to provide a thermal spraying apparatus that can suppress generation of unnecessary droplets and a method of using the same.
[0014]
[Means for Solving the Problems]
The thermal spraying apparatus according to the present invention is The powder of the thermal spray raw material from the injection port of the powder supply pipe Spray gun Ejected from the nozzle at the tip By supplying the heat source, the powder is melted or semi-molten and sprayed onto the workpiece to form a film, During the time when no film is formed on the workpiece Equipped with air piping that injects compressed air ing. This air pipe is arranged outside the powder supply pipe with its injection port facing the injection port of the powder supply pipe, and injects compressed air in a direction that prevents the supply of powder to the heat source. (Claim 1).
[0015]
The powder of the thermal spray raw material is supplied to the heat source of the thermal spray gun from the spray port of the powder supply pipe, and is sprayed on the object to be processed as a droplet. At this time, when compressed air is injected from the air pipe toward the injection port of the powder supply pipe, the powder that has come out of the injection port is blown off by the compressed air. Thereby, since supply to the heat source of powder is prevented, generation | occurrence | production of an unnecessary droplet is suppressed.
[0016]
A thermal spraying apparatus according to a second aspect is the thermal spraying apparatus according to the first aspect, further comprising dust collecting means for collecting the powder blown off by the compressed air. Since the blown powder is collected by the dust collecting means, the powder that is not in the form of droplets can be easily collected and scattered to the peripheral devices.
[0017]
A thermal spraying apparatus according to a third aspect is the thermal spraying apparatus according to the first or second aspect, wherein the pressure of the compressed air is higher than the gas pressure in the powder supply pipe. If the pressure of the compressed air is higher than the gas pressure in the powder supply pipe, the powder discharged from the powder supply pipe can be easily blown away by the compressed gas, so that the introduction of the powder into the heat source can be efficiently suppressed.
[0018]
A thermal spraying apparatus according to a fourth aspect is the thermal spraying apparatus according to any one of the first to third aspects, wherein an injection port of the powder supply pipe is located on an extension line of the air pipe. In other words, the injection port of the air pipe is provided so as to overlap the injection port surface of the powder supply tube. At this time, the powder is quickly sucked out by the principle of spraying. Here, the principle of spraying will be described. When a thin tube is erected in a container containing water and air is allowed to flow through the upper end portion of the tube, a contracted portion is generated in the air flow path, and the velocity of air in this portion increases. Therefore, the pressure is reduced at the upper end of the pipe by Bernoulli's theorem. When there is no air flow at the upper end of the pipe, the water level in the pipe remains constant and stable. On the other hand, a pressure gradient is generated in the pipe by generating the air flow, and the water sucked up to the upper end of the pipe scatters in the form of a mist downstream with the air flow. This is the principle of spraying.
[0019]
The thermal spraying device according to claim 5 is the thermal spraying device according to any one of claims 1 to 4, wherein an angle formed by the center line of the powder supply pipe and the center line of the air pipe is more than 0 degree and not more than 90 degrees. (However, the case where the extension directions of these center lines coincide with each other is set to 0 degree). At this time, the composition vector of the gas flow discharged from the powder supply pipe and the air pipe does not generate a component for pushing the powder back to the powder supply pipe. Therefore, the powder is efficiently blown away without pushing the powder back into the powder supply pipe. In particular, it is most effective when the angle is 90 degrees.
[0020]
A thermal spraying apparatus according to claim 7 is the thermal spraying apparatus according to any one of claims 1 to 6, wherein the thermal spraying apparatus moves the powder from the powder tank to the powder supply pipe via the supply hose, on the flow of the powder supply gas. The powder is supplied from the spray port of the powder supply pipe to the heat source of the spray gun. In this thermal spraying apparatus, since the powder tank and the powder supply pipe are separated from each other, a supply hose connecting the powder tank and the powder supply pipe is required. For this reason, the powder remains in the supply hose, so that a lot of unnecessary droplets are generated as it is. Therefore, when the powder remaining in the supply hose comes out of the powder supply pipe, the generation of unnecessary droplets is suppressed by blowing it off with compressed air. Thus, the effects of the present invention are remarkably exhibited.
[0021]
When using the thermal spraying apparatus according to any one of claims 1 to 7 to form a film continuously on a plurality of objects to be processed, the usage method according to claim 8 is applied to one object to be processed. On the other hand, after the formation of the film, the compressed air is injected from the air pipe and the heat generation operation of the heat source is maintained until the formation of the film on the next object is started. During the time when no film is formed on the workpiece, the heat generation operation of the heat source is not stopped, but compressed air is injected. Thereby, generation | occurrence | production of an unnecessary droplet can be suppressed, without reducing the lifetime of a spray gun, and preventing a continuous operation. In particular, plasma spraying is preferable because the life of the electrode is likely to be reduced by turning on and off the power supply (claim 9).
[0022]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first embodiment of a thermal spraying apparatus according to the present invention, FIG. 1 [1] is a side view, FIG. 1 [2] is a front view, and FIG. 2 is an enlarged view of the main part of FIG. It is a figure (the 1). Hereinafter, description will be given based on these drawings. However, the same parts as those in FIG. 7 and FIG.
[0023]
The thermal spraying apparatus 10 of this embodiment supplies the powder 84 of the thermal spray raw material to the plasma jet 76 of the thermal spray gun 71 from the injection port 811 of the powder supply pipe 81, thereby melting the powder 84 and subject to treatment (not shown). ) To form a film, and is characterized in that an air pipe 12 for injecting compressed air 11 from the outside of the powder supply pipe 81 toward the injection port 811 of the powder supply pipe 81 is provided. Specifically, the powder 84 is moved from the powder tank (not shown) to the powder supply pipe 81 through the supply hose 82 in the flow of the powder supply gas 90, and the powder 84 is injected into the injection port 811 of the powder supply pipe 81. To the plasma jet 76 of the spray gun 71.
[0024]
The powder supply pipe 81 is bent in an L shape from the side surface of the nozzle 74 along the tip surface, and is fixed to the nozzle 74 by a fixing member 822. The air pipe 12 is also bent in an L shape from the side surface of the nozzle 74 along the tip surface, and is fixed to the nozzle 74 by a fixing member (not shown).
[0025]
The powder 84 of the thermal spray raw material is supplied to the plasma jet 76 of the thermal spray gun 71 from the injection port 811 of the powder supply pipe 81, and is sprayed on the object to be processed as a droplet. At this time, when the compressed air 11 is injected from the air pipe 12 toward the injection port 811 of the powder supply pipe 81, the powder 84 that has come out of the injection port 811 is blown off by the compressed air 11. Thereby, since supply of the powder 84 to the plasma jet 76 is hindered, generation of unnecessary droplets can be suppressed. Further, since the powder tank and the powder supply pipe 81 are separated from each other in the thermal spraying apparatus 10, a supply hose 82 that connects the powder tank and the powder supply pipe 81 is necessary. For this reason, the powder 84 remains in the supply hose 82, so that a lot of unnecessary droplets are generated as it is. Therefore, when the powder 84 remaining in the supply hose 82 comes out from the powder supply pipe 81, the compressed air 11 blows off the powder 84, thereby suppressing generation of unnecessary droplets.
[0026]
FIG. 3 is an enlarged view (part 2) of the main part of FIG. 1 [2]. Hereinafter, it will be described in more detail based on FIG. 1 and FIG.
[0027]
In the present embodiment, an air pipe 12 dedicated to residual powder removal is installed beside the powder supply pipe 81. At this time, the injection port 121 of the air pipe 12 is overlapped with the injection port 81 of the powder supply pipe 81, that is, the injection port 811 of the powder supply pipe 81 is positioned on the extension line 122 of the air pipe 12. Install. And after spraying to a to-be-processed object, supply of the powder 84 is stopped and the compressed air 11 higher than the powder supply gas 90 is simultaneously injected from the air piping 12. As a result, the powder 84 remaining in the supply hose 82 deviates from the trajectory entering the plasma jet 76 and therefore does not become droplets.
[0028]
Here, the angle α formed by the center line 812 of the powder supply pipe 81 and the center line 123 of the air pipe 12 is desirably 90 °. However, if the powder 84 blown by the compressed air 11 does not enter the plasma jet 76, it may be 0 ° <α <90 ° (the case where the extending directions of the center lines 812 and 123 coincide with each other is 0 °). . On the other hand, when α> 90 °, the compressed air 11 pushes the powder 84 back into the powder supply pipe 81, which is not preferable. Further, since the air pipe 12 is arranged so that the jet port 121 of the air pipe 12 overlaps from the side of the jet port 811 of the powder supply pipe 81, the powder 84 is quickly sucked out by the principle of spraying. As a result, the inside of the supply hose 82 is immediately cleaned, and stable powder supply becomes possible.
[0029]
Next, an example of how to use the thermal spraying apparatus 10 will be described. When the thermal spraying apparatus 10 is used to continuously form a film on a plurality of objects to be processed, after the formation of the film on one object to be processed is completed, the film is applied to the next object to be processed. In addition to stopping the supply of the powder 84 from the powder tank and maintaining the supply of the powder supply gas 90, the compressed air 11 is injected from the air pipe 12 and the plasma jet 76 Maintain heat generation. That is, during the time when the film is not formed on the object to be processed, the compressed air 11 is injected instead of stopping the heat generation operation of the plasma jet 76. Thereby, generation | occurrence | production of an unnecessary droplet can be suppressed, without reducing the lifetime of the electrode of the spray gun 71, and preventing a continuous operation. The means for controlling the injection of the compressed air 11 from the air pipe 12, the means for controlling the supply of the powder 84 from the powder tank, and the means for controlling the supply of the powder supply gas 90 are, for example, electromagnetic valves. The means for controlling the heat generation operation of the plasma jet 76 is, for example, a switch that applies or cuts off the power supply voltage to the electrode of the spray gun 71.
[0030]
FIG. 4 is an enlarged view of a main part showing a second embodiment of the thermal spraying apparatus according to the present invention. Hereinafter, description will be given based on this drawing. However, the same parts as those in FIG.
[0031]
The thermal spraying apparatus 20 of the present embodiment includes a dust collection tube 21 as dust collection means for collecting the powder 84 blown off by the compressed air 11. The dust collection tube 21 has a conical opening at the distal end, a proximal end connected to a pump (not shown) or the like, and an air flow 22 for sucking the powder 84 is generated. According to the thermal spraying device 20, the blown-off powder 84 is collected by the dust collection tube 21, so that the powder 84 that is not in the form of droplets can be easily collected and scattered to the peripheral devices.
[0032]
In other words, since the air pipe 12 is disposed so as to overlap the jet port 121 of the air pipe 12 from right next to the jet port 811 of the powder supply pipe 81, the range in which the powder 84 is blown off by the compressed air 11 is also limited. The By disposing the dust collection tube 21 in that range, it is possible to easily collect the powder 84 that is not a droplet. Needless to say, the dust collecting tube 21 is merely an example of a dust collecting means, and may have any shape and structure as long as the powder 84 blown off can be collected.
[0033]
FIG. 5 shows a third embodiment of the thermal spraying apparatus according to the present invention, FIG. 5 [1] is a front view, and FIG. 5 [2] is a side view. Hereinafter, description will be given based on these drawings. However, the same parts as those in FIG.
[0034]
The thermal spraying apparatus 30 of this embodiment supplies the powder 84 of the thermal spray raw material from the injection port 311 of the powder supply pipe 31 to the plasma jet 33 of the thermal spray gun 32, thereby melting the powder 84 and subject to treatment (not shown). ) To form a film, and is characterized in that an air pipe 34 for injecting compressed air 11 from the outside of the powder supply pipe 31 toward the injection port 311 of the powder supply pipe 31 is provided. Specifically, the powder 84 is moved to the powder supply pipe 31 through a powder tank and a supply hose (not shown) in the flow of the powder supply gas 90, and the powder 84 is sprayed from the injection port 311 of the powder supply pipe 31 to the thermal spray gun 32. The plasma jet 33 is supplied.
[0035]
The powder supply pipe 31 is bent into a square shape from the side surface of the nozzle 35 along the tip surface, and is fixed to the nozzle 35 by a fixing member 822. The air pipe 34 is also bent in an L shape from the side surface of the nozzle 35 along the tip surface, and is fixed to the nozzle 35 by a fixing member (not shown). The thermal spraying device 30 of this embodiment also has the same operation and effect as the thermal spraying device 10 (FIG. 1) of the first embodiment. Moreover, you may provide the dust collection means which collects the powder 84 blown off by the compressed air 11 similarly to 2nd embodiment.
[0036]
As shown in FIG. 1, in the thermal spraying apparatus 10 of the first embodiment, the tip of the thermal spray gun 71 is cylindrical, and the plasma jet 76 is ejected in the axial direction of the thermal spray gun 71. In contrast, in the thermal spraying apparatus 30 of the present embodiment, the tip of the thermal spray gun 35 has a wedge shape, and the plasma jet 33 is ejected in an oblique direction with respect to the axis of the thermal spray gun 35. Therefore, the spray droplets can be sprayed in the circumferential direction of the spray gun 35 by rotating the spray gun 35 around the axis. That is, the thermal spraying device 30 is suitable for forming a film on the inner peripheral surface of a cylindrical workpiece.
[0037]
【Example】
Next, an example using the thermal spraying apparatus 30 of the third embodiment will be described with reference to FIGS. 6 [1] is a schematic diagram showing the production line, FIG. 6 [2] is an enlarged view showing the blasting process in the production line of FIG. 6 [1], and FIG. 6 [3] is in the production line of FIG. It is an enlarged view which shows a thermal spraying process.
[0038]
The blasting process 41 and the thermal spraying process 42 in FIG. 6 [1] are enlarged and shown in FIGS. 6 [2] and [3], respectively. The production line shown in FIG. 6 [1] is an all-aluminum spray cylinder 45 in which the conventional cast iron sleeve is abolished by coating the inner surface 43 of the aluminum cylinder bore with a coating 44 having wear resistance. Is to be manufactured.
[0039]
First, in order to give adhesion to the coating 44, an elongated blast gun 46 is inserted into the cylinder bore 47, and a hard abrasive (alumina particles) 48 is sprayed from the tip of the blast gun 46 toward the cylinder bore inner surface 43, so that the cylinder bore The inner surface 43 is roughened (blasting process). Subsequently, an elongated spray gun 32 that generates the plasma jet 33 from the tip is inserted into the cylinder bore 47. At the same time when the tip of the spray gun 32 reaches the cylinder bore lower end portion 49, the powder 84 is introduced into the plasma jet 33 from the powder supply pipe 31, thereby causing the droplets 50 to adhere to the cylinder bore inner surface 43 to form the coating 44. (The spraying process).
[0040]
In addition, the air pipe 34 is arranged directly beside the injection port 311 of the powder supply pipe 31 so that the injection port 341 of the air pipe 34 is opposed. Furthermore, in the thermal spraying process, after the coating 44 was sufficiently formed up to the cylinder bore upper end 51, the supply of the powder 84 was stopped. Thereafter, the powder 84 remaining in the supply hose was removed by injecting the compressed air 11 from the air pipe 34. Details of installation, processing conditions, effects, etc. of the air pipe 34 will be described below.
[0041]
(1) Installation of air piping 34
The air pipe 34 was arranged so that the compressed air 11 directly hits the injection port 311 of the powder supply pipe 31. At this time, the distance h (FIG. 5 [1]) between the center line of the powder supply pipe 31 and the injection port 341 of the air pipe 34 was 3 mm. And these were arrange | positioned so that the injection port 311 of the powder supply pipe | tube 31 may be located on extension of the centerline of the air piping 34. FIG. Moreover, the angle α formed by the center line of the powder supply pipe 31 and the center line of the air pipe 34 was 90 °.
[0042]
(2) Injection condition of compressed air 11
The injection conditions are shown below.
Air piping opening diameter φ2mm
Injection flow rate 30 l / min
Injection time Continuous injection for 3 seconds after powder supply is stopped
[0043]
(3) Blasting conditions
As the blasting material, white alundum was used, and a direct pressure blasting apparatus was used. The blast injection angle was 90 deg. Details are shown below.
Blast type Direct pressure type
Blast injection angle 90deg
Blast gun rotation speed 46rpm
Direct pressure nozzle diameter φ6mm
Injection pressure 392 kPa (4 kgf / cm ² )
Blasting material White Alundum # 30
Blast gun moving speed 5mm / sec
[0044]
(4) Thermal spraying conditions
Thermal spraying method Plasma spraying
Spray angle 45deg
Supply current 800A
Main gas flow rate (Ar) 56.8 l / min
Auxiliary gas flow rate (He) 7.6 l / min
Powder supply pipe opening diameter φ2mm
Powder supply gas flow rate (Ar) 5.3 l / min
Formed film thickness 200μm
[0045]
(5) Effect
140 spraying cylinders 45 were produced. After the completion, no adhesion of droplets to the peripheral device was observed. In addition, by arranging the dust collecting tube near the jet of the compressed air 11, the powder 84 that did not become droplets was suppressed from being scattered to the peripheral device and could be reliably recovered. Since the powder 84 at this time was not a droplet, it could be easily recovered and discarded. Further, after the 140 spraying cylinders 45 were finished, the supply hose was removed and the residual degree of the powder 84 was confirmed. As a result, the powder 84 did not remain.
[0046]
Needless to say, the present invention is not limited to the above embodiment. For example, a separate type in which the spray gun and the powder tank are separated is illustrated, but the present invention can also be applied to an integrated type in which the spray gun and the powder tank are integrated without a supply hose. The reason for this is that there are powders that remain in the portion directly connecting the spray gun and the powder tank or in the powder supply pipe. Further, as long as the thermal spraying apparatus can use powder as the thermal spraying raw material, the heat source is not limited to plasma, and may be a combustion flame, an arc, a laser, or the like.
[0047]
【The invention's effect】
According to the thermal spraying apparatus according to the present invention, the powder of the thermal spray raw material is supplied to the thermal source of the thermal spray gun from the spray port of the powder supply pipe, and the powder is melted and sprayed on the workpiece to form a coating. By providing an air pipe that injects compressed air from the outside of the tube toward the injection port of the powder supply tube, it is possible to blow off the powder that has come out of the injection port with compressed air. Can be suppressed.
[0048]
According to the thermal spraying apparatus of claim 2, by providing the dust collecting means for collecting the powder blown off by the compressed air, it is possible to facilitate the recovery of the powder and to suppress the scattering to the peripheral device. .
[0049]
According to the thermal spraying apparatus of claim 3, since the pressure of the compressed air is made higher than the gas pressure in the powder supply pipe, the powder discharged from the powder supply pipe can be easily blown away by the compressed gas. Entering the heat source can be efficiently suppressed.
[0050]
According to the thermal spraying apparatus of the fourth aspect, since the injection port of the powder supply pipe is located on the extended line of the air pipe, the powder in the powder supply pipe can be quickly sucked out by the principle of spraying.
[0051]
According to the thermal spraying apparatus of claim 5, since the angle formed by the center line of the powder supply pipe and the center line of the air pipe is more than 0 degree and not more than 90 degrees, the powder is not pushed back into the powder supply pipe. Can be efficiently blown away. In particular, according to the thermal spraying apparatus of the sixth aspect, the powder can be blown out most efficiently by setting the angle to 90 degrees.
[0052]
According to the thermal spraying apparatus of Claim 7, since powder tends to remain in the supply hose connecting the powder tank and the powder supply pipe, generation of unnecessary droplets is greatly suppressed by blowing the powder away with compressed air. be able to.
[0053]
According to the method for using the thermal spraying device according to claim 8, after the formation of the film on one object to be processed is completed, the air pipe is used until the start of film formation on the next object to be processed. By injecting compressed air and maintaining the heat generation operation of the heat source, it is possible to suppress the generation of unnecessary droplets without reducing the life of the spray gun and without disturbing continuous operation. In particular, when plasma is used as the heat source, the life of the electrode is likely to be shortened by turning on and off the power source, so that a greater effect can be obtained.
[Brief description of the drawings]
FIG. 1 shows a first embodiment of a thermal spraying apparatus according to the present invention, FIG. 1 [1] is a side view, and FIG. 1 [2] is a front view.
FIG. 2 is an enlarged view (No. 1) of a main part of FIG. 1 [2].
FIG. 3 is an enlarged view (No. 2) of main parts of FIG. 1 [2].
FIG. 4 is an enlarged view of a main part showing a second embodiment of the thermal spraying apparatus according to the present invention.
FIG. 5 shows a third embodiment of the thermal spraying apparatus according to the present invention, FIG. 5 [1] is a front view, and FIG. 5 [2] is a side view.
6 shows an embodiment using the thermal spraying apparatus of FIG. 5, FIG. 6 [1] is a schematic diagram showing a production line, and FIG. 6 [2] shows a blasting process in the production line of FIG. 6 [1]. FIG. 6 [3] is an enlarged view showing a thermal spraying process in the production line of FIG. 6 [1].
FIG. 7 is a cross-sectional view schematically showing a conventional plasma spraying apparatus.
8 is a schematic view showing how to use the plasma spraying apparatus of FIG. 7, and the process proceeds in the order of FIG. 8 [1] to FIG. 8 [3].
[Explanation of symbols]
10, 20, 30 Thermal spraying device
11 Compressed air
12, 34 Air piping
121,341 Air piping injection port
21 Dust collection pipe (dust collection means)
32,71 Thermal spray gun
33,76 Plasma jet (heat source)
31,81 Powder supply pipe
311 and 811 powder supply pipe injection port
82 Supply hose
83 Powder tank
84 powder
90 Powder supply gas

Claims (9)

A thermal spraying apparatus that forms a film by spraying the powder to be processed in a molten or semi-molten state by supplying the powder of the thermal spray raw material from the spray port of the powder supply pipe to a heat source ejected from the nozzle at the tip of the thermal spray gun In
An air pipe for injecting compressed air at a time when the film is not formed on the workpiece ;
The air pipe is disposed outside the powder supply pipe in a state where the injection port of the air pipe faces the injection port of the powder supply pipe, and the compressed air is directed in a direction in which the supply of the powder to the heat source is hindered. Inject,
A thermal spraying device characterized by that. The thermal spraying device according to claim 1, further comprising dust collecting means for collecting the powder blown off by the compressed air. The thermal spraying device according to claim 1 or 2, wherein a pressure of the compressed air is higher than a gas pressure in the powder supply pipe. The thermal spraying device according to any one of claims 1 to 3, wherein an injection port of the powder supply pipe is located on an extension line of the air pipe. The angle formed between the center line of the powder supply pipe and the center line of the air pipe is more than 0 degree and not more than 90 degrees when the extension direction of these center lines coincides with 0 degree. The thermal spraying apparatus in any one of thru | or 4. The thermal spraying apparatus according to claim 5, wherein the angle is 90 degrees. The powder is moved to the powder supply pipe via a supply hose from the powder tank, and the powder is supplied from the injection port of the powder supply pipe to the heat source of the thermal spray gun. Item 7. The thermal spraying apparatus according to any one of Items 1 to 6. When using the thermal spraying device according to any one of claims 1 to 7 to continuously form a coating on a plurality of objects to be processed,
After the formation of the film on one object to be processed, the compressed air is sprayed from the air pipe and the heat generation operation of the heat source is performed until the formation of the film on the next object to be processed is started. How to use thermal spray equipment to maintain. The method of using a thermal spraying device according to claim 8, wherein the heat source is plasma.

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