JP2004082024A - Internal supply type flame spraying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the workability by reducing or automating a work removing the powder clogging of a jet orifice. <P>SOLUTION: A flame spraying apparatus 10 is constituted so that the jet orifice 11 of a powder supply pipe 72 is provided in a flame spraying gun 71, a powder 76 of a flame spraying raw material is supplied to a plasma jet 74 from the jet orifice 11 to be melted and the molten powder 76 is sprayed on an article to be treated to form a film. Air piping 13 for ejecting compressed air 12 to the jet orifice 11 from the inside of the powder supply pipe 72 is provided in the flame spraying gun 71. By this constitution, the adherend of the jet orifice 11 is blown off by compressed air 12 to be returned to the flow of the powder 76 in the jet orifice 11. The formation of the adherend at the jet orifice 11 being a problem peculiar to an internal supply type can be dissolved simply without decomposing the flame spraying gun 71 and interrupting flame spraying work. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides an injection port of a powder supply pipe in a thermal spray gun, and supplies a powder of a thermal spraying material to a heat source from the injection port, thereby spraying the powder in a molten or semi-molten state to an object to be processed. The present invention relates to an internal supply type thermal spraying device (hereinafter, simply referred to as a "thermal spraying device") for forming the above.
[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. The substance for forming this film is applicable to any substance that does not evaporate or decompose with a heat source, such as metal, ceramics, and plastic. As the heat source, a combustion flame, arc, plasma, laser, or the like is used.
[0003]
When an inert gas flows between the electrodes and discharge occurs, the inert gas is ionized and becomes high-temperature and high-speed plasma. A thermal spraying method using this plasma as a heat source is plasma spraying. Generally, a water-cooled nozzle-shaped copper anode and tungsten cathode are used with argon as a working gas. When an arc is generated between these electrodes, the working gas is turned into plasma by the arc, and is ejected from the nozzle as a high-temperature and high-speed plasma jet. The powder of the thermal spray material is injected into the plasma jet, heated and accelerated and sprayed on the substrate. In flame spraying using a combustion flame, the theoretical maximum temperature of the sprayed flame is about 3000 ° C. On the other hand, in plasma spraying, since there is no theoretical upper limit in the plasma gas temperature, thermal plasma of about 5,000 to 10,000 ° C. is usually used, so that it is suitable for spraying a high melting point material.
[0004]
The plasma spraying apparatus is classified into an external supply system and an internal supply system depending on whether the powder of the spray material is supplied from the outside or the inside of the spray gun. The internal supply method has an advantage that the powder is in the plasma jet for a longer time than the external supply method, so that the powder can be easily melted and a dense film can be easily formed. FIG. 7 is a schematic cross-sectional view showing a conventional internal supply type plasma spraying apparatus. Hereinafter, description will be made based on this drawing.
[0005]
The plasma spraying device 70 includes a spray gun 71, a powder supply pipe 72, a powder tank 73, and the like. Inside the thermal spray gun 71, an injection port 721 of a powder supply pipe 72, and a cathode and an anode (not shown) are provided. When a working gas (not shown) is introduced into the spray gun 71 to generate an arc between the cathode and the anode, the working gas is turned into plasma, and a high-temperature and high-speed plasma jet 74 is jetted. On the other hand, a powder supply gas 75 flows from the powder tank 73 into the powder supply pipe 72, and the powder 76 of the thermal spray material is put on the powder supply gas 75 and transported to the thermal spray gun 71. As a result, the powder 76 is supplied to the plasma jet 74, and the powder 76 is melted and sprayed on an object to be processed (not shown) to form a film. Further, outside the plasma jet 74, a thermal spray frame 77 made of powder 76 that has become a droplet is formed.
[0006]
[Problems to be solved by the invention]
However, the plasma spraying apparatus 70 has a problem peculiar to the internal supply method, that is, a problem that the powder 76 tends to adhere and clog at the injection port 721. FIG. 8 is a sectional view of a main part showing a problem of the plasma spraying apparatus of FIG. 7, and time elapses in the order of FIG. 8 [1] to FIG. 8 [3]. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG.
[0007]
FIG. 8A shows a normal case in which the adhesion and clogging of the powder 76 have not occurred. In this case, all of the powder 76 injected from the injection port 721 is injected into the plasma jet 74 to form a droplet, and is injected from the thermal spray gun 71 as the thermal spray frame 77.
[0008]
FIG. 8B shows a case where the adhesion and clogging of the powder 76 have started to occur. When the powder 76 starts to adhere to the thermal spray port 721, the diameter of the spray port 721 gradually decreases due to the generation of the deposit 761. Therefore, the amount of the powder 76 injected into the plasma jet 74 from the injection port 721 decreases, and the amount of the thermal spray frame 77 ′ also decreases.
[0009]
FIG. 8C shows the case where the adhesion and clogging of the powder 76 have further progressed. Generally, cooling water is passed through the spray gun 71 to protect the spray gun 71 from the high temperature plasma jet 74. Therefore, when the powder 76 which is jetted toward the plasma jet 74 to become a droplet is attached to the periphery of the jet port 721, it is cooled and solidified. Then, since the powder 76 attached to the periphery of the injection port 721 is cooled by the influence of the cooling water, it is unlikely that the powder 76 is again formed as a molten droplet and is injected outside the thermal spray gun 71. On the contrary, it becomes a large deposit 762, which causes the deposition of droplets thereon, and also impedes the flow of the powder 76 in the powder supply pipe 72. As a result, the amount of the thermal spray frame 77 "is further reduced. That is, the film forming speed is greatly reduced.
[0010]
When the powder 76 further adheres to the injection port 721, the powder 76 is clogged in the powder supply pipe 72, so that the injection of the powder 76 from the injection port 721 stops. This stop means that the injection of the powder 76 into the plasma jet 74 stops, and the spraying frame 77 does not occur and the film cannot be formed. When the clogging of the powder 76 occurs, the powder supply pipe 72 is removed from the thermal spray gun 71, and the powder 76 attached to the powder supply pipe 72 and the injection port 721 is removed.
[0011]
As described above, in the plasma spraying apparatus 70 of the internal supply system, it is necessary to interrupt the thermal spraying operation from time to time to disassemble the thermal spray gun 71 and remove the clogged powder 76. The interruption of the thermal spraying operation has reduced the workability, thereby increasing the production cost of the workpiece.
[0012]
[Object of the invention]
Therefore, a main object of the present invention is to provide a thermal spraying apparatus in which workability is improved by reducing or automating the work of removing powder clogged in an injection port.
[0013]
[Means for Solving the Problems]
The thermal spraying apparatus according to the present invention is provided with an injection port of a powder supply pipe in a thermal spray gun, and supplies the powder of the thermal spray raw material to the heat source from the injection port to spray the powder in a molten or semi-molten state to the workpiece. In the method for forming a film by spraying, an air pipe for injecting compressed air from an inside of the powder supply pipe toward an injection port of the powder supply pipe is provided in the spray gun.
[0014]
The powder of the thermal spray raw material is supplied to the heat source of the thermal spray gun from the injection port of the powder supply pipe, and is sprayed as a droplet onto the workpiece. On the other hand, a part of the powder adheres to the injection port, and the attached matter increases with the elapse of the spraying time, so that the flow of the powder in the injection port is obstructed. Therefore, when the compressed air is sometimes injected from the air pipe toward the injection port during the spraying operation, the adhered substance at the injection port is blown off by the compressed air, and the flow of the powder in the injection port returns to the original state. As described above, the generation of deposits at the injection port, which is a problem peculiar to the internal supply system, can be easily solved without the necessity of disassembling the thermal spraying gun and without interrupting the thermal spraying operation. The reference of the timing of injecting the compressed air may be, for example, a fixed time, or may be a pressure in a powder tank or a powder supply pipe as described later.
[0015]
According to a second aspect of the present invention, in the thermal spraying apparatus according to the first aspect, the powder supply pipe is provided perpendicular to a center line of the heat source, and an injection port of the powder supply pipe and an injection port of the air pipe overlap. The powder supply pipe and the air pipe are connected to each other. The angle between the air pipe and the powder supply pipe at these injection ports is 0 degree when the extension direction of the air pipe matches the extension direction of the powder supply pipe, and the extension direction of the air pipe is Assuming that 90 degrees is perpendicular to the extending direction and on the side where the film is formed, the angle is more than 0 degrees and less than 90 degrees. At this time, in the flow of the compressed air injected from the air pipe, there is no component generated in the direction opposite to the direction in which the heat source sprays the droplet. That is, since the compressed air is not injected against the flow of the droplets, the deterioration of the state of the heat source is suppressed, whereby a good film is formed even during the injection of the compressed air.
[0016]
According to a third aspect of the present invention, in the thermal spraying apparatus of the first or second aspect, the air pipe injects the compressed air toward the heat source through the injection port of the powder supply pipe. The compressed air injected from the air pipe blows off the powder attached to the injection port and throws the powder into a heat source. In other words, the powder attached to the injection port is not discarded but is effectively used.
[0017]
According to a fourth aspect of the present invention, in the thermal spraying apparatus of the third aspect, when the center line of the injection port of the air pipe is extended, the center line intersects the center line of the heat source. At this time, the compressed air injected from the air pipe blows off the powder attached to the injection port, and throws the powder into the center of the heat source. Therefore, the powder attached to the injection port is not discarded but is effectively used, and the powder is put into the center of the heat source, so that the powder is in a good molten state.
[0018]
According to a fifth aspect of the present invention, in the thermal spraying apparatus according to the second aspect, when the diameter of the air pipe is φA [mm], the diameter of the powder supply pipe is φD [mm], and the angle is θ, the following relationship is satisfied. ΦDcos θ ≦ φA ≦ φD + 2. As the diameter of the air pipe is larger, the flow rate of compressed air can be increased, so that the deposits on the injection port can be easily blown off, while adversely affecting the heat source, such as obstructing the flow of droplets or lowering the temperature of the heat source. give. Therefore, an upper limit of φA ≦ φD + 2 is provided for the diameter of the air pipe. Conversely, if the diameter of the air pipe is too small, the powder supply pipe and the air pipe cannot be connected so that the injection port of the powder supply pipe and the injection port of the air pipe overlap. That is, the injection port of the air pipe is opened on the inner wall of the powder supply pipe. Then, even if compressed air is injected from the air pipe, it is difficult to blow off the attached matter at the injection port. Therefore, a lower limit of φDcosθ ≦ φA is provided for the diameter of the air pipe.
[0019]
According to a sixth aspect of the present invention, in the thermal spraying apparatus according to any one of the first to fifth aspects, an automatic valve provided in the air pipe for opening and closing a compressed air flow path, and a powder tank connected to the powder supply pipe. A pressure sensor for measuring the internal pressure, and a control unit for controlling the opening and closing of the flow path by the automatic valve in accordance with the pressure measured by the pressure sensor. The pressure in the powder tank changes according to the presence or absence of powder clogging at the injection port. Therefore, by using a pressure sensor, an automatic valve and a control unit to open and close the flow path of the compressed air in accordance with the pressure in the powder tank, an appropriate timing (timing) according to the state of the powder attached to the injection port. Then, compressed air can be automatically injected. The automatic valve is a valve that opens and closes automatically, not manually, and is, for example, an electromagnetic valve using a solenoid or an electric valve using a motor.
[0020]
In the thermal spraying device according to a seventh aspect, in the thermal spraying device according to the sixth aspect, the control unit operates as follows. When the pressure measured by the pressure sensor is equal to or higher than the first set value, the flow path of the compressed air is opened through the automatic valve, and when the pressure measured by the pressure sensor is equal to or less than the second set value. The compressed air flow path is closed via an automatic valve. When deposits are generated at the injection port, the pressure in the powder tank increases due to the narrowing of the injection port. At this time, the compressed air flow path is opened via the automatic valve, and the compressed air is ejected to remove the deposit. Then, when the injection port is widened by removing the deposits, the pressure in the powder tank decreases. At this time, the compressed air flow path is closed via the automatic valve, and the outflow of the compressed air is stopped. In this way, by stopping the compressed air when the pressure in the powder tank returns to the set value, the spraying operation can be performed with minimal effect on the heat source, that is, without significantly affecting the state of the coating. Can be performed continuously.
[0021]
The thermal spraying device according to claim 8 is the thermal spraying device according to claim 7, wherein the second set value is a normal value without powder adhesion and clogging at the injection port, and the first set value is higher than the normal value. This is a value increased by 25%. That is, when the pressure in the powder tank rises 25% from normal, the flow path of the compressed air is opened via the automatic valve, and when the pressure in the powder tank returns to normal, the compressed air is released via the automatic valve. Close the flow path. The reason why the first set value for injecting the compressed air is set to 25% of the normal value is as follows, for example. As the first set value is higher than 25% of the normal value, the variation in the flow of the powder increases, and the variation in the film forming speed also increases, thereby easily affecting the formed film. Conversely, the lower the first set value is below 25% of the normal value, the more frequently compressed air is jetted, so that the formed film is more likely to be affected. Therefore, by setting the first set value to 25% of the normal value, it is possible to remove adhesion and clogging of the powder without significantly changing the formed film. In other words, the first set value is preferably 20% to 30% of the normal value, more preferably 23% to 27% of the normal value, and most preferably 25% of the normal value.
[0022]
According to a ninth aspect of the present invention, in the thermal spraying apparatus according to any one of the first to eighth aspects, the heat source is plasma. Since plasma becomes extremely hot compared to other heat sources, plasma has advantages such as being suitable for thermal spraying of high melting point materials.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a schematic sectional view showing a first embodiment of a thermal spraying device according to the present invention. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG. 7 and FIG.
[0024]
The thermal spraying apparatus 10 of the present embodiment includes the injection port 11 of the powder supply pipe 72 in the thermal spray gun 71, and melts the powder 76 by supplying the powder 76 of the thermal spraying material to the plasma jet 74 from the injection port 11. The film is formed by spraying the material to be processed (not shown). An air pipe 13 for injecting compressed air 12 from the inside of the powder supply pipe 72 toward the injection port 11 of the powder supply pipe 72 is provided in the thermal spray gun 71.
[0025]
The powder supply tube 72 includes a powder supply hole in the thermal spray gun 71 and a flexible tube outside the thermal spray gun 71 detachably connected to the powder supply hole. The air pipe 13 includes a compressed air hole in the thermal spray gun 71 and a flexible tube outside the thermal spray gun 71 detachably connected to the compressed air hole. The injection port 11 of the powder supply pipe 72 also serves as an injection port of the compressed air 12 injected from the air pipe 13.
[0026]
The powder 76 is supplied from the injection port 11 of the powder supply pipe 72 to the plasma jet 74 of the thermal spray gun 71, and is sprayed as a droplet onto the workpiece. On the other hand, a part of the powder 76 adheres to the injection port 11, and the attached matter increases as the spraying time elapses, so that the flow of the powder 76 in the injection port 11 is hindered. Therefore, when the compressed air 12 is sometimes injected from the air pipe 13 toward the injection port 11 during the spraying operation, the deposits (not shown) on the injection port 11 are blown off by the compressed air 12 and the powder 76 in the injection port 11 is removed. Flow returns. As described above, the generation of the deposit at the injection port 11, which is a problem peculiar to the internal supply system, can be easily solved without the necessity of disassembling the thermal spray gun 71 and without interrupting the thermal spraying operation.
[0027]
FIG. 2 shows a main part of a second embodiment of the thermal spraying apparatus according to the present invention, wherein FIG. 2 [1] is a schematic diagram viewed from an arrow II of FIG. 2 [2], and FIG. 2 [2] is a sectional view. . Hereinafter, description will be made based on this drawing. However, the description of the same parts as those in FIG. 1 will be omitted by omitting illustration or attaching the same reference numerals.
[0028]
In the thermal spraying apparatus 20 of the present embodiment, the powder supply pipe 72 is provided perpendicular to the center line 741 of the plasma jet 74, and the injection port 11 of the powder supply pipe 72 and the injection port 11 of the air pipe 13 overlap. The powder supply pipe 72 and the air pipe 13 are connected. The angle θ between the air pipe 13 and the powder supply pipe 72 at the injection port 11 is 0 degree when the extension direction of the air pipe 13 matches the extension direction of the powder supply pipe 72, and the extension direction of the air pipe 13 Is 90 degrees when the angle is perpendicular to the extension direction of the powder supply pipe 72 and on the side on which the film is formed, the angle is more than 0 degrees and less than 90 degrees.
[0029]
At this time, the flow of the compressed air 12 injected from the air pipe 13 does not include a component opposite to the direction in which the plasma jet 74 sprays the droplet. That is, since the compressed air 12 is not injected against the flow of the droplets, the deterioration of the state of the plasma jet 74 is suppressed, and a good film is formed even during the injection of the compressed air 12.
[0030]
In other words, the air pipe 13 is disposed so as to be connected to the powder supply pipe 72 at the injection port 11, and the angle θ between the air pipe 13 and the powder supply pipe 72 satisfies the relationship of 0 ° <θ <90 °. The reason for setting 0 ° <θ <90 ° is that the state of the plasma jet 74 deteriorates when the compressed air 12 is injected against the plasma jet 74.
[0031]
In the thermal spraying device 20, the air pipe 13 injects the compressed air 12 toward the plasma jet 74 via the injection port 11 of the powder supply pipe 72. In addition, when the center line (not shown) at the injection port 11 of the air pipe 13 is extended, this center line intersects with the center line 741 of the plasma jet 74. Therefore, the compressed air 12 injected from the air pipe 13 blows off the powder 76 attached to the injection port 11, and the powder 76 is further injected into the center of the plasma jet 74. Therefore, the powder 76 adhering to the injection port 11 is not discarded but is effectively used, and is put into the center of the plasma jet 74 to be in a good molten state.
[0032]
FIG. 3 shows a main part of a third embodiment of the thermal spraying apparatus according to the present invention. FIG. 3 [1] is a schematic diagram viewed from an arrow III in FIG. 3 [2], and FIG. 3 [2] is a sectional view. . Hereinafter, description will be made based on this drawing. However, the description of the same parts as those in FIGS. 1 and 2 will be omitted by omitting illustration or by attaching the same reference numerals.
[0033]
In the thermal spraying apparatus 30 of this embodiment, the diameter of the air pipe 13 is φA [mm], the diameter of the powder supply pipe 72 is φD [mm], and the angle between the air pipe 13 and the powder supply pipe 72 at the injection port 11 is θ. Satisfies the following relationship.
φDcosθ ≦ φA ≦ φD + 2
[0034]
As the diameter of the air pipe 13 is larger, the flow rate of the compressed air 12 can be increased, so that the deposits on the injection port 11 can be easily blown off, while preventing the flow of droplets, lowering the temperature of the plasma jet 74, and the like. Adversely affects the plasma jet 74. Therefore, an upper limit of φA ≦ φD + 2 is provided for the diameter φA of the air pipe 13.
[0035]
Conversely, if the diameter φA of the air pipe 13 is too small, the powder supply pipe 72 and the air pipe 13 cannot be connected so that the injection port 11 of the powder supply pipe 72 and the injection port 11 of the air pipe 13 overlap. That is, the injection port of the air pipe 13 is opened on the inner wall of the powder supply pipe 72. Then, even if the compressed air 12 is injected from the air pipe 13, it is difficult to blow off the attached matter at the injection port 11. Therefore, a lower limit of φDcosθ ≦ φA is set for the diameter φA of the air pipe 13.
[0036]
The lower limit value of the diameter φA of the air pipe 13 will be described in more detail. The powder supply pipe 72 is arranged perpendicular to the center line 741 of the plasma jet 74, and the opening of the powder supply pipe 72 in the spray gun 71 is circular. On the other hand, the air pipe 13 is disposed obliquely with respect to the center line 741 of the plasma jet 74, and the opening shape of the air pipe 13 in the spray gun 71 is elliptical (the length in the longitudinal direction is B). Become. Here, in order to prevent the injection port of the air pipe 13 from opening on the inner wall of the powder supply pipe 72, it is necessary to satisfy B ≧ φD. At this time, since φA / B = cos θ, B = φA / cos θ, and therefore φA ≧ φDcos θ.
[0037]
FIG. 4 is a schematic sectional view showing a fourth embodiment of the thermal spraying apparatus according to the present invention. Hereinafter, description will be made based on this drawing. However, the same parts as those in FIG.
[0038]
The thermal spraying device 40 according to the present embodiment includes an electromagnetic valve 41 provided in the air pipe 13 for opening and closing the flow path of the compressed air 12, and a pressure in a powder tank 73 connected to a powder supply pipe 72 (hereinafter referred to as “tank internal pressure”). ), And a control unit 43 that controls the opening and closing of the flow path by the electromagnetic valve 41 in accordance with the tank internal pressure measured by the pressure sensor 42.
[0039]
The electromagnetic valve 41 includes a solenoid and a valve, and the solenoid operates in response to an external signal to open and close the valve. The pressure sensor 42 includes, for example, a piezoelectric element or the like, and outputs a signal corresponding to the tank internal pressure (atmospheric pressure). For the control unit 43, a microcomputer is suitable for performing complicated control, and a simple electronic circuit is sufficient for performing simple control. Further, a pressure sensor 42 provided with a control unit 43 in advance may be used.
[0040]
FIG. 5 is a cross-sectional view of a main part showing the operation of the thermal spraying device 40, and time elapses in the order of FIGS. 5 [1] to 5 [3]. Hereinafter, the operation of the thermal spraying device 40 will be described with reference to FIGS. However, the description of the same parts in FIG. 5 as those in FIG. 4 will be omitted by omitting illustration or giving the same reference numerals.
[0041]
First, when there is no adhesion and clogging of the powder 76 in the injection port 11, the tank internal pressure indicated by the pressure gauge 42 is a normal value (FIG. 5 [1]). Subsequently, when deposits (adhesion and clogging) 44 occur at the injection port 11, the pressure in the tank increases due to the narrowing of the injection port 11. Then, when the tank internal pressure rises by 25% from the normal value, the controller 43 opens the flow path of the compressed air 12 via the electromagnetic valve 41 (FIG. 5 [2]) and injects the compressed air 12 to 44 is removed. At this time, since there is also an effect of sucking out the powder 76 clogged in the powder supply pipe 72, elimination of the powder clogging is promoted. Subsequently, when the injection port 11 is widened by removing the deposits 44, the tank internal pressure decreases (FIG. 5 [3]). Then, when the tank internal pressure returns to the normal value, the control unit 43 closes the flow path of the compressed air 12 via the electromagnetic valve 41 and stops the outflow of the compressed air 12 (FIG. 5 [1]). The reason why the compressed air 12 is stopped in this manner is that the conditions (the amount of the powder, the charging speed, etc.) of the powder 76 to be injected into the plasma jet 74 are changed by the injection of the compressed air 12, and the properties of the resulting film are changed. Is to minimize the change.
[0042]
The injection amount of the compressed air 12 may be adjusted according to the state of the plasma jet 74, for example, the output state. This is because the injection amount of the compressed air 12 that hardly affects the plasma jet 74 changes according to the state of the plasma jet 74.
[0043]
【Example】
Next, an example using the thermal spraying device 40 of the fourth embodiment will be described with reference to FIGS. FIG. 6 is a schematic diagram showing a production line.
[0044]
The production line shown in FIG. 6 performs a blast process and a thermal spray process on the sample 51 while moving the lowered sample 51 to the sample moving line 50. The blast gun 52 and the thermal spray gun 71 are mounted on traverse devices 53 and 54, respectively. For the sample 51, a plate material (50 × 80 × t8 mm) made of an aluminum casting alloy (AC4C) was used. A mixed powder of iron and aluminum was used as the thermal spray material.
[0045]
First, the surface of the sample 51 is roughened using a blast gun 52 in order to increase the adhesion of the thermal spray coating. At this time, the blast gun 52 is moved like a movement locus 55. Subsequently, a thermal spray coating having abrasion resistance is formed on the surface of the roughened sample 51 using a thermal spray gun 71. At this time, the spray gun 71 is moved like a movement locus 56. Hereinafter, blast conditions, thermal spray conditions, and results will be described in detail.
[0046]
(1) Blast conditions
As a blast material, white alundum was used, and a direct pressure blast device was used. Details are shown below.
Blast type Direct pressure type
Blast distance 100mm
Blast injection angle 90deg
Direct pressure nozzle diameter φ6mm
Injection pressure 392kPa (4kgf / cm ² )
Blast material White Alundum $ 30
Blast gun moving speed 5mm / sec
[0047]
(2) Thermal spray conditions
An Fe—Al composite thermal spray coating was formed. Thermal spraying conditions were set as follows.
Thermal spray gun type
Powder supply method Internal supply method
Spraying method Plasma spraying
Spray distance 100mm
Spray angle 90 deg
Supply current 800A
Active gas flow rate (Ar) 56.8 l / min
Auxiliary gas flow rate (He) 7.6 l / min
Diameter of powder supply hole φ2mm
Powder supply gas flow rate (Ar) 5.3 l / min
Film thickness 200μm
Diameter of compressed air hole φ2mm
Compressed air flow rate 15 l / min
Normal time powder tank internal pressure 55kPa (8psi)
Internal pressure of powder tank during air injection 69kPa (10psi)
[0048]
(3) Result
The blast processing and the thermal spraying processing were performed on the 60 prepared samples 51 continuously for one hour. As a result, an increase in the tank internal pressure of the powder tank 73 was observed about every 10 minutes. Then, when the tank internal pressure increased by 25% from the normal value, the tank internal pressure could be returned to the normal value by injecting the compressed air 12. After the treatment for one hour, the injection port 11 was examined. As a result, no deposits or clogging of the powder were observed. Further, the thermal spray coating formed when the internal pressure of the tank was increased was observed, but no remarkable change was observed.
[0049]
It is needless to say that the present invention is not limited to the above embodiment. For example, if the thermal spraying apparatus can use powder as a thermal spraying material, the heat source is not limited to plasma, but may be a combustion flame, an arc, a laser, or the like.
[0050]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the thermal spraying apparatus which concerns on this invention, the injection | pouring opening of a powder supply pipe is provided in a spraying gun, and the powder to be processed is made into a molten or semi-molten state by supplying powder of a thermal spray raw material to a heat source from an injection orifice. In the spray gun, the air pipe that sprays compressed air from the inside of the powder supply pipe toward the injection port of the powder supply pipe is provided inside the spray gun, so that the By injecting compressed air, it is possible to blow off deposits at the injection port. Therefore, it is possible to solve the problem of deposits at the injection port, which is a problem peculiar to the internal supply method, easily without disassembling the spray gun and without interrupting the spraying work. Can be improved.
[0051]
According to the thermal spraying device of the second aspect, the powder supply pipe is provided perpendicular to the center line of the heat source, and the powder supply pipe and the air pipe are arranged such that the injection port of the powder supply pipe and the injection port of the air pipe overlap. And the angle between the air pipe and the powder supply pipe at the injection port is set to more than 0 degree and less than 90 degrees, so that the compressed air is not injected against the flow of the droplets. As a result, a good film can be formed even during the injection of compressed air.
[0052]
According to the thermal spraying device of the third aspect, the blown powder is injected into the heat source by injecting the compressed air toward the heat source through the injection port of the powder supply pipe, so that the powder attached to the injection port can be removed. It can be used effectively instead of being discarded.
[0053]
According to the fourth aspect of the present invention, when the center line at the injection port of the air pipe is extended, the center line intersects the center line of the heat source, so that the blown powder is injected into the center of the heat source. By doing so, the powder adhering to the injection port can be effectively used instead of being discarded. In addition, since the powder is put into the center of the heat source, the powder is in a good molten state, whereby a good film can be formed.
[0054]
According to the thermal spraying apparatus of the fifth aspect, when the diameter of the air pipe is φA [mm], the diameter of the powder supply pipe is φD [mm], and the angle between the air pipe and the powder supply pipe is θ, φDcosθ ≦ Since φA ≦ φD + 2 is satisfied, it is possible to reliably remove deposits on the injection port while suppressing adverse effects on the heat source. That is, by setting φA ≦ φD + 2, it is possible to suppress the adverse effect on the heat source, and by setting φDcosθ ≦ φA, it is possible to reliably remove deposits on the injection port.
[0055]
According to the thermal spraying device of the sixth aspect, an automatic valve provided in the air pipe for opening and closing the flow path of the compressed air, a pressure sensor for measuring the pressure in the powder tank connected to the powder supply pipe, and a pressure sensor With the control unit that controls the opening and closing of the flow path by the automatic valve according to the measured pressure, the flow path of the compressed air can be opened and closed according to the pressure in the powder tank. The compressed air can be automatically injected at an appropriate time according to the condition of the attached powder. Therefore, it is possible to easily solve the problem of deposits at the injection port, which is a problem peculiar to the internal supply system, without the necessity of disassembling the spray gun, etc., and automatically without interrupting the spraying work. Properties can be further remarkably improved.
[0056]
According to the thermal spraying apparatus of claim 7, when the pressure measured by the pressure sensor becomes equal to or more than the first set value, the compressed air flow path is opened via the automatic valve, and the pressure measured by the pressure sensor When the pressure in the powder tank returns to the set value by closing the compressed air flow path via the automatic valve when the pressure becomes less than the second set value, the compressed air is stopped. The deposits on the injection port can be surely removed while minimizing the amount of water. That is, the thermal spraying operation can be performed continuously without significantly affecting the state of the coating.
[0057]
According to the thermal spraying device of the eighth aspect, the flow path of the compressed air is opened when the pressure in the powder tank rises by 25% than usual, and the flow of the compressed air is opened when the pressure in the powder tank returns to normal. By closing the path, the adhesion and clogging of the powder can be removed without significantly changing the formed film. That is, by setting the set value for injecting compressed air to 25% of the normal value and the set value for stopping the compressed air to the normal value, the formed film is formed as compared with the case where the set value is set to any other value. To the effect.
[0058]
According to the thermal spraying apparatus of the ninth aspect, the heat source is a plasma, so that the advantages of the present invention such as the improvement of the workability described above can be obtained while utilizing the advantages specific to the plasma such as being suitable for thermal spraying of a high melting point material. In addition, usefulness can be improved, for example, it can be used in more fields.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a first embodiment of a thermal spraying apparatus according to the present invention.
2 shows a main part of a second embodiment of a thermal spraying apparatus according to the present invention, wherein FIG. 2 [1] is a schematic view as viewed from an arrow II of FIG. 2 [2], and FIG. 2 [2] is a sectional view. is there.
3 shows a main part of a third embodiment of a thermal spraying apparatus according to the present invention, wherein FIG. 3 [1] is a schematic diagram viewed from an arrow III of FIG. 3 [2], and FIG. 3 [2] is a sectional view. is there.
FIG. 4 is a schematic sectional view showing a second embodiment of the thermal spraying device according to the present invention.
5 is a cross-sectional view of a main part showing the operation of the thermal spraying apparatus of FIG. 4, and time elapses in the order of FIG. 5 [1] to FIG. 5 [3].
FIG. 6 is a schematic diagram showing a production line in one embodiment using the thermal spraying apparatus of FIG.
FIG. 7 is a schematic cross-sectional view showing a conventional internal supply type plasma spraying apparatus.
8 is a sectional view of a main part showing a problem of the plasma spraying apparatus of FIG. 7, and time elapses in the order of FIG. 8 [1] to FIG. 8 [3].
[Explanation of symbols]
10,20,30,40 Thermal spraying equipment
11 injection port
12 Compressed air
13 Air piping
41 Electromagnetic valve (automatic valve)
42 pressure sensor
43 Control unit
71 Spray gun
72 Powder supply pipe
73 powder tank
74 plasma jet (heat source)
75 Powder supply gas
76 powder

Claims (9)

An inner portion of a spray gun provided with an injection port of a powder supply pipe, in which the powder of the thermal spray raw material is supplied to a heat source from the injection port to make the powder in a molten or semi-molten state and spray the object to form a film. In the supply type thermal spraying equipment,
An air pipe for injecting compressed air from the inside of the powder supply pipe toward an injection port of the powder supply pipe was provided in the thermal spray gun,
An internal supply type thermal spraying device characterized by the above-mentioned. The powder supply pipe is provided perpendicular to the center line of the heat source, and the powder supply pipe and the air pipe are connected such that an injection port of the powder supply pipe and an injection port of the air pipe overlap with each other,
The angle between the air pipe and the powder supply pipe at these injection ports is 0 degree when the extension direction of the air pipe matches the extension direction of the powder supply pipe, and the extension direction of the air pipe is the When the angle perpendicular to the extending direction of the powder supply pipe and on the side on which the film is formed is 90 degrees, the angle is more than 0 degree and less than 90 degrees.
The internal supply type thermal spraying device according to claim 1. The air pipe injects the compressed air toward the heat source through an injection port of the powder supply pipe,
The internal supply type thermal spraying device according to claim 1. When extending the center line at the injection port of the air pipe, the center line intersects the center line of the heat source,
The internal supply type thermal spraying apparatus according to claim 3. When the diameter of the air pipe is φA [mm], the diameter of the powder supply pipe is φD [mm], and the angle is θ, the following relationship is satisfied.
φDcosθ ≦ φA ≦ φD + 2,
An internal supply type thermal spraying apparatus according to claim 2. An automatic valve provided in the air pipe for opening and closing the flow path of the compressed air, a pressure sensor for measuring a pressure in a powder tank connected to the powder supply pipe, and a pressure sensor according to the pressure measured by the pressure sensor. A control unit that controls opening and closing of the flow path by the automatic valve,
The internal supply type thermal spraying device according to any one of claims 1 to 5, further comprising: The control unit opens the flow path via the automatic valve when the pressure measured by the pressure sensor is equal to or greater than a first set value, and the pressure measured by the pressure sensor is set to a second set value. Closing the flow path via the automatic valve when the value becomes equal to or less than the value,
An internal supply type thermal spraying apparatus according to claim 6. The second set value is a normal value without adhesion and clogging of the powder at the injection port, and the first set value is a value that is 25% higher than the normal value.
The internal supply type thermal spraying apparatus according to claim 7. The heat source is a plasma;
An internal supply type thermal spraying apparatus according to claim 1.

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