JP2002060923A - Method for forming sprayed coating on inner surface of metal tube, and thermal spraying gun and thermal spraying apparatus for forming spray coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably increase the corrosion resistance and durability by depositing, in place of a conventional vinyl chloride lining, a sprayed coating on the inner surface of a metal tube having a diameter of <=450 mm used for water supply pipes in general homes and buildings. SOLUTION: An angle is formed between a torch and a sprayed coating forming surface by bending the torch 2 side of a thermal spraying gun 1. A wear resistant coating layer 36 is formed on the inner surface of a bent portion of a powder feed pipe 5 in the inside of the thermal spraying gun 1. The torch 2 is cooled with water. The powder feeding apparatus 15 comprises a powder chamber 16, a gear 17, a variable motor 18, a powder charging port 19, a carrier gas inlet 20, a vibrator air inlet 21, a powder discharging port 22, and a powder feeder 23. The film is deposited by using nozzles 4 of the plurality of thermal spraying guns 1 in a manner displaced like comb teeth or by making the thermal spraying guns 1 face each other from openings at both ends in the long metal pipe 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a thermal spray coating on the inner surface of a metal pipe for transporting various fluids, for example, a metal pipe having a diameter of 450 mm or less, and a thermal spraying method used for carrying out this method. The present invention relates to a gun and a thermal spraying device for supplying a thermal spray material.

[0002]

2. Description of the Related Art A thermal spray gun used in a conventional thermal spraying apparatus has a linear shape, and a torch portion is formed at the tip of the gun body. Therefore, in order to form a thermal spray coating on the inner surface of a metal tube using a conventional thermal spray gun, it is necessary to put the thermal spray gun in the metal tube and make the thermal spray angle as close to a right angle as possible. Therefore, there is a limit to the diameter of a tube that can be sprayed, and so far, it has been applicable only to a tube having a diameter of 450 mm or more.

However, in various fluid transport pipes, 45
There is a great demand for metal pipes having a thermal spray coating even on pipes of 0 mm or less.For example, in metal pipes for water supply with vinyl chloride lining on the inner surface, in order to further improve corrosion resistance and durability, instead of vinyl chloride lining, There is a demand for supply of a water pipe having a sprayed film formed thereon. But,
In such a water pipe, there is not much demand for a metal pipe having a diameter of 450 mm or more, and the diameter of a water pipe used in a general home or a building is almost 450 mm or less. If a thermal spray coating can be formed on a metal pipe having the following diameter, a water pipe having extremely high corrosion resistance and durability as compared with vinyl chloride lining can be constructed.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a 450 m water pipe mainly used for ordinary households and buildings.
In other words, a thermal spray coating is formed on the inner surface of a metal tube having a diameter of m or less in place of the conventional vinyl chloride lining, and the improvement of corrosion resistance and durability is remarkably enhanced by this coating. Furthermore, in addition to the water pipe, a spraying method applicable to forming a sprayed coating on the inner surface of a small-diameter pipe having a diameter of 450 mm or less for corrosion resistance, chemical resistance, and the like, a spray gun used for the method, and a spraying apparatus It is to provide.

[0005]

According to a first aspect of the present invention, there is provided a method of forming a thermal spray coating on an inner surface of a metal tube, wherein a spray gun having a torch side bent is provided. The spray coating is formed by moving the spray gun in the tube axis direction while rotating the metal tube while rotating the metal tube.

Further, in the invention according to claim 2,
According to the first aspect of the present invention, the thermal spraying gun is fixed, and the thermal spray coating is formed while moving the metal pipe side in the pipe axis direction.

Further, in the invention according to claim 3,
In the invention according to claim 1 or 2, the sprayed coating material is blown out from the center of the torch, and the flammable gas is blown out from a crater formed around the center to melt the sprayed coating material. Is applied to the inner surface of the metal tube to form a thermal spray coating.

Further, in the invention according to claim 4,
The invention according to claim 1, 2 or 3 is characterized in that the spraying gun is cooled by a water cooling system.

Further, in the invention described in claim 5,
In the thermal spray gun, a thermal spray gun body having a torch side bent, a thermal spray material outlet formed in the center of the torch, a crater formed around the thermal spray material outlet, and a cooling water flow path in the torch portion. Is formed.

Further, in the invention according to claim 6,
According to a fifth aspect of the present invention, the inner surface of the bent portion of the supply pipe to which the thermal spray material is supplied is coated with a wear-resistant material.

Further, in the invention according to claim 7,
In the invention according to claim 6, the coating of the wear-resistant material includes inserting the wear-resistant material into the bent portion of the supply tube, heating the supply tube from the outside at the bent portion, rotating the supply tube, and performing the heating. It is characterized by being manufactured by a method in which a wear-resistant material is melted to form a film on the inner surface of a bent portion.

Further, in the invention according to claim 8,
In the invention according to claim 6 or 7, the wear-resistant material used is Ni-Cr or an alloy powder obtained by mixing boron or silicon with Ni-Cr.

Further, in the invention according to claim 9,
In the invention according to claim 5 or 6, or 7 or 8, a cooling water passage is formed in the torch, and pressurized cooling water circulates in the cooling water passage so as to prevent overheating of the torch portion. It is characterized by being constituted.

Further, according to the present invention, in a thermal spraying apparatus for continuously supplying a thermal spraying material to a thermal spraying gun in a constant amount, a powder chamber into which the thermal spraying material is charged, and a bottom portion of the powder chamber. A gear chamber formed in the horizontal direction, a fixed-amount supply gear incorporated in the gear chamber, a motor for driving the fixed-amount supply gear, and a carrier gas inlet formed at a lower portion and a vibrator air supply port. And a powder feeder formed by forming a powder supply port of the gear chamber above the introduction port and the supply port, and forming a pressurized powder discharge port on the upper part. It is.

[0015]

The thermal spraying material is continuously supplied to the thermal spraying gun from the powder supply device by a fixed amount, and is ejected from the center of the torch. On the other hand, a flammable gas is supplied to the crater of the torch, where an injection combustion flame is formed. The thermal spray material is melted by the combustion flame, collides with the inner surface of the metal tube by the kinetic energy of the spray flame, and is laminated thereon to form a thermal spray coating. In this thermal spraying, since the torch side of the thermal spray gun is bent, it is easy to make an angle with respect to the inner surface of the metal tube, and the thermal spray coating can be efficiently laminated and formed. Further, when the thermal spray material passes through the bent portion, the inner surface of the passage is coated with a wear-resistant material, so that the passage of the bent portion is not worn by the thermal spray material.

By rotating the metal tube during the spraying using the spray gun and simultaneously moving the spray gun in the tube axis direction or by fixing the spray gun and moving the metal tube in the tube axis direction, The thickness of the thermal spray coating can be freely set by adjusting the rotation and the moving speed. Further, in the film forming operation, the spraying gas may be inserted from the openings at both ends of the metal tube so as to face each other, and the sprayed film may be formed using two spraying guns. Alternatively, the sprayed coating may be formed by directing the torches of the plurality of spray guns radially or by shifting the torches in a comb shape in the tube axis direction.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an embodiment diagram showing the general concept of the thermal spraying method and the apparatus according to the first to tenth aspects. First, in FIG. 1, reference numeral 1 denotes a thermal spray gun,
The torch 2 side of the spray gun 1 is bent at an angle of about 45 ° on the way, and an injection nozzle 3 for ejecting a spray material (hereinafter referred to as “powder”) is provided at the center of the torch 2. In addition, a ring-shaped crater 4 is provided around the nozzle and concentrically with the injection nozzle 3. Note that the bending angle of the torch 2 is arbitrary.

In FIG. 2, reference numeral 5 denotes a powder carrier gas supply pipe connected from the injection nozzle 3 to the powder carrier gas inlet 6 at the rear end through the center in the cylindrical gun body 1a;
Reference numeral 7 denotes a combustible gas supply pipe connected to the crater 4 and a rear end combustible gas inlet 8, reference numeral 9 denotes an oxygen supply pipe connected from the mixing chamber 11 in the torch 2 to a rear end oxygen inlet 10. After the combustible gas and oxygen are premixed in the mixing chamber 11, they are ejected forward from the crater 4. Reference numeral 12 denotes a cooling water passage formed inside the torch 2. The cooling water passage 12 and a cooling water inlet 14 at the rear end are connected by a cooling water supply pipe 13, and cooling water circulates, and a portion of the torch 2 is formed. Cool and prevent overheating.

In FIG. 1, reference numeral 15 denotes a powder supply device. As shown in FIG. 3, the supply device 15 is assembled so as to cross the bottom of a powder chamber 16 into which powder as a thermal spray material has been introduced. A fixed speed supply gear 17, a variable speed motor 18 for driving the gear 17,
A powder inlet 19 is formed at the front end, and a carrier gas inlet 20 and a vibrator air inlet 21 are formed at the bottom.
Powder feeder 2 having powder discharge port 22 formed on top
The powder discharge port 22 and the powder carrier gas inlet 6 are connected by a powder delivery line 22a.

In FIG. 1, reference numeral 24 denotes a thermal spray control device. The thermal spray control device 24 controls the flow rate and the pressure of an oxygen delivery line 25 and a combustible gas delivery line 26 with respect to the spray gun 1, and further includes the above-described components. A carrier gas delivery line 27 for delivering to the carrier gas inlet 20 of the powder supply device 15, a vibrator delivery line 28 for delivering vibrator air to the vibrator air inlet 21, and cooling for delivering cooling water to the cooling water inlet 14. The flow rate and pressure of the water delivery line 29 are controlled. The cooling water delivery line 29 and the cooling water inlet 14 are singly illustrated in FIG. 1, but are actually two reciprocating passages, and the cooling water circulates.

Reference numeral 30 denotes an oxygen cylinder connected to the powder control device 24 by a line 30a, 31 denotes a combustible gas cylinder connected by a line 31a, 32 denotes a carrier gas cylinder connected by a line 32a, and 33 denotes a carrier gas cylinder connected by a line 33a. Pressurized air delivery compressor, 34 is a cooling water circulation line 34a
It is a cooling water generator connected by. Reference numeral 35 denotes a carrier gas switching valve attached to the carrier gas delivery line 27. Reference numeral 36 denotes a wear-resistant coating layer formed on the inner surface of the bent member 5a of the powder supply pipe 5 at the bent portion of the spray gun 1, and the coating layer 36 is
A wear-resistant material was inserted into a, and the member 5a was heated from the outside to melt the wear-resistant material, rotated at the same time, and then cooled to form a wear-resistant coating layer 36 on the inner surface.
The composition of the wear-resistant material of the wear-resistant coating layer 36 is NI-Cr (91.25% by weight), B (2% by weight), Si (2% by weight), C (0.25% by weight). ,
A powder material (70% by weight) composed of F (4% by weight) and Co (0.5% by weight) and WC (30% by weight).

FIG. 4 shows an example of thermal spraying performed by using the above apparatus.
Details will be described based on (A) and (B). First, the metal tube 50 is placed on rollers (tables) 51 and 52 that are rotated by a motor (not shown). Then, a wire 53 is passed through the metal tube 50, and the spray gun 1 is hooked up with a hook 59 connected to the wire 53. The spray gun 1 is supported by a support 54 with wheels 55 to determine its position in the metal tube 50. Also, spray gun 1
Behind the hook 5 connecting the strength member 56 to the wire 53
9 and a supporting member 57 with wheels 58, and the strength member 56 is further connected with a powder delivery hose, a flammable gas hose, an oxygen hose, and the like.
In the metal tube 50 by a slide device not shown,
It retreats along the tube axis while being guided by the wire 53. In forming the thermal spray coating, the rollers 51 and 52 on which the metal tube 50 is placed are rotated to supply powder and flammable gas from the powder control device 24 to the thermal spray gun 1 and ignite the crater 4. The powder is melted by the combustion flame, and the inner surface 5
A thermal spray coating A is formed on Oa. In this thermal spraying, the strength material 56 is pulled backward along the wire 53, and the thermal spray gun 1
Is retreated in the tube axis direction, so that the thermal spray coating A is formed on the entire inner surface of the metal tube 50.

In the embodiment, the wear-resistant material coated on the inner surface of the bent portion of the powder supply pipe 5 is, for example, N
An alloy powder composed of i (95% by weight) + Cr (5% by weight) was used. Next, Table 1 shows examples of the spraying conditions of each alloy powder, and Table 2 shows examples of the characteristics of the sprayed coating.

[0024]

[Table 1]

[0025]

[Table 2]

FIG. 5 shows an example in which the craters 4 of the torches 2 of a plurality of thermal spray guns 1 are displaced into a comb shape in the tube axis direction and inserted into a metal tube 50 to efficiently form a thermal spray coating A. 6 is a metal tube 5
This is an example in which the thermal spray coating A is formed while the thermal spray gun 1 is inserted from the openings at both ends of the metal tube 50 so as to face each other. This method is used when the thermal spray coating A is formed on the inner surface of the long metal tube 50. It is valid. 5 and 6 may be used in combination.

[0027]

According to the present invention, the structure and operation described above
The following effects are obtained. 1. By bending the torch side of the spray gun, the spray angle with respect to the inner surface of the metal tube can be increased.
Even in the case of a small-diameter tube of about 0 mmφ, a thermal spray coating can be formed. 2. Since the inner surface of the bent portion of the powder supply tube is coated with a wear-resistant material in the spray gun, the inner surface of the bent portion is not worn by the moving powder, and the durability is increased.

3. By using a water-cooled torch part, not only is the cooling effect higher than with the conventional air method, but also because air is not discharged into the tube to be sprayed, a high-quality sprayed film is formed especially for small-diameter tubes. Or a good working environment. 4. By ejecting the powder from the center of the ring-shaped crater, it is possible to improve the melting rate of the powder and prevent the diffusion of flying particles, and to form a uniform film.

5. By rotating the metal tube and further moving the metal tube in the axial direction, or by performing the thermal spraying while moving the spray gun in the tube axial direction, for example, automatic thermal spraying can be performed on a small-diameter tube of 450 mm or less. 6. By inserting a plurality of spraying guns into a metal tube and shifting the crater into a comb shape or changing the direction of the crater and performing spraying, film formation can be performed efficiently. 7. By forming the film by inserting the thermal spray guns from the openings at both ends of the metal tube so as to face each other, it is particularly easy to form a long metal tube. 8. The powder is mixed with a carrier gas by a vertical powder feeder in a powder supply device and is converted into a pressurized fluid, so that the powder can be supplied to the powder supply port with a stable amount and pressure (flow rate). . 9. By incorporating the powder supply tube inside the spray gun instead of outside as in the prior art, the powder supply tube does not interfere when working in a small diameter tube.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration of an entire thermal spraying apparatus.

FIG. 2 is an explanatory view of a thermal spray gun.

FIG. 3 is an explanatory diagram of a powder supply device.

FIG. 4 is an explanatory view of a state in which the inner surface of the metal tube is being thermally sprayed.

FIG. 5 is an explanatory view of an example in which a plurality of thermal spray guns are used in a comb shape.

FIG. 6 is an explanatory view of an example in which a spraying gun is inserted from openings at both ends of a metal tube so as to face each other and spraying is performed.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 spray gun 1a gun body 2 torch 3 injection nozzle 4 crater 5 powder carrier gas supply pipe 6 powder carrier gas inlet 7 flammable gas supply pipe 8 flammable gas inlet 9 oxygen supply pipe 10 oxygen inlet 11 mixing chamber 12 cooling water channel 13 Cooling Water Supply Pipe 14 Cooling Water Inlet 14a Cooling Water Outlet 15 Powder Supply Device 16 Powder Chamber 17 Gear 18 Variable Speed Motor 19 Powder Inlet 20 Carrier Gas Inlet 21 Vibrator Air Inlet 22 Powder Outlet 23 Powder Feeder Reference Signs List 24 spraying control device 25 oxygen delivery line 26 flammable gas delivery line 27 carrier gas delivery line 28 vibrator delivery line 29 cooling water delivery line 30 oxygen cylinder 31 flammable gas cylinder 32 carrier gas cylinder 33 compressed air delivery compressor 34 cooling water generator 3 5 Carrier gas switching valve 36 Wear-resistant coating layer 50 Metal tube 51, 52 Rotating roller 53 Wire 54 Support 55 Wheel 56 Strength member 57 Support 58 Wheel 59 Hook A Thermal spray coating

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F16L 58/08 F16L 58/08 F term (Reference) 3H024 EA01 EC03 ED08 EE01 4D075 AA18 AA33 AA35 AA65 AA68 DA19 DB01 EA02 4F033 QA01 QB02X QB02Y QB05 QB12X QG14 QG20 QK16X QK18X QK23X QK27X 4K031 AA01 AB02 AB08 CB08 CB22 DA01 EA01 EA03 EA07 FA02

Claims (10)

[Claims] 1. A thermal spray gun having a torch side bent is inserted into a metal tube to be sprayed, and then the thermal spray gun is moved in the axial direction of the metal tube while rotating the metal tube. Method of forming a thermal spray coating on the inner surface of 2. The method according to claim 1, wherein the spraying gun is fixed.
A method of forming a thermal spray coating on the inner surface of a metal tube while moving the metal tube side in the tube axis direction. 3. The sprayed coating material according to claim 1 or 2, wherein the sprayed coating material is ejected from a central portion of the torch, and a flammable gas is ejected from a crater formed around the central portion, thereby melting the sprayed coating material. A method of forming a thermal spray coating on the inner surface of the metal tube by colliding this with the inner surface of the metal tube to form a thermal spray coating. 4. The method according to claim 1, wherein the thermal spray gun is cooled by a water cooling method. 5. A thermal spray gun body having a torch side bent, a thermal spray material outlet formed at the center of the torch, a crater formed around the thermal spray material outlet, and a cooling water flow in the torch portion. A thermal spray gun that forms a path. 6. The thermal spray gun according to claim 5, wherein the inner surface of the bent portion of the supply pipe to which the thermal spray material is supplied is coated with a wear-resistant material. 7. The coating of a wear-resistant material according to claim 6, wherein the wear-resistant material is inserted into a bent portion of the supply tube, the supply tube is heated from the outside at the bent portion, and the supply tube is rotated. A thermal spray gun manufactured by a method in which a wear-resistant material is melted to form a film on an inner surface of a bent portion. 8. The thermal spray gun according to claim 6, wherein the wear-resistant material used is Ni—Cr or an alloy powder obtained by mixing boron or silicon with the material. 9. The method of claim 5, 6 or 7 or 8,
A spray gun, wherein a cooling water passage is formed in the torch, and pressurized cooling water is circulated in the cooling water passage to prevent overheating of the torch portion. 10. A powder chamber into which a thermal spray material is charged, a gear chamber formed in a bottom portion of the powder chamber in a horizontal direction, a fixed-rate supply gear incorporated in the gear chamber, and driving the fixed-rate supply gear. A carrier gas inlet at the bottom and a vibrator air supply at the bottom, a powder supply at the gear chamber above the inlet and the supply, and a pressurized powder discharge at the top. A spraying apparatus for continuously supplying a sprayed material to a spraying gun, characterized by comprising a powder feeder having an outlet.