JP2986305B2 - Plasma spray gun for inner surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent corrosion resistance, abrasion resistance and the like on the inner surfaces of pipes and vessels used in environments where corrosion and wear are severe, such as oil drilling pipes and chemical reaction vessels. The present invention relates to an inner surface plasma spray gun used for spraying a material.

[0002]

2. Description of the Related Art A conventional inner surface plasma spray gun is shown in FIG.
As shown in the figure, structurally, it is easier to supply powder to the nozzle when the powder supply tube is outside the body of the spray gun,
A powder supply pipe 8 was provided outside the main body of the plasma spray gun 2 for the inner surface, and the pipe 8 was connected to an injector 9 adjacent to the nozzle 3 to supply a spray powder to the plasma jet 6.

[0003]

However, when the powder supply pipe 8 is outside the main body of the plasma spray gun 2 for the inner surface, there are the following problems. (1) The powder supply pipe 8 directly receives radiation heat of the object to be sprayed heated by the plasma spraying and the temperature rises. Along with this, the supplied thermal spray powder receives heat from the tube 8 and rises in temperature to soften, so that the supply of the thermal spray powder deteriorates and the tube 8 is easily clogged. Therefore, the quality of the thermal spray coating becomes poor due to the variation in the supply amount of the thermal spray powder, and the processing cost increases.

(2) In order to perform good quality thermal spraying on a metal material to be sprayed by plasma spraying in a reduced pressure atmosphere,
It is effective to remove impurities (such as an oxide film) on the surface of the object to be sprayed before and during thermal spraying. For this, a negative transfer arc treatment is generally employed.
In this process, a negative voltage is applied to the metal material to be sprayed in an inert gas atmosphere and a positive voltage is applied to the anode 4 of the spray gun for the inner surface, and the cleaning action by the transfer arc through the plasma frame is used. To remove the oxide film on the surface of the object to be sprayed. However, when a conductive powder is used for thermal spraying, and the powder supply pipe 8 connected to the anode 4 of the inner surface spray gun 2 has conductivity, the pipe 8 has the same potential as the anode 4. Therefore, a negative transfer arc is generated between the tube 8 and the object to be sprayed via the powder scattered in the atmosphere, and the tube 8 is extremely consumed.

[0005]

The present invention SUMMARY OF THE INVENTION The plasma spray gun apparatus odor for performing thermal spraying on the inner surface of the pipe such <br/> Te, into the processing vessel, the system or outside of the pipe which is an object to be sprayed product
Rotatable by these rotary motors, and
Provide a vacuum pump, spray powder and plasma gas
Spraying with an internal supply passage and cooling water circulation passage inside
The gun is driven inside the pipe by a travel motor from outside the system.
By arranging them so as to reciprocate in the directions, it is possible to solve the above-mentioned problems of the prior art.

[0006]

Hereinafter, a powder supply pipe 8 and a powder supply path 10 for supplying a thermal spray powder into the plasma jet 6 will be described.
An embodiment of the spray gun 2 for the inner surface, which is provided in the casing of the spray gun body which is water-cooled, will be described with reference to FIGS.

First, the inside of the processing container 1 is evacuated by a vacuum pump 16 via a pipe 17. After the evacuation is completed, an appropriate amount of inert gas is filled and a predetermined atmospheric pressure is set.
Next, a plasma jet 6 is generated from the nozzle 3 of the spray gun 2 for the inner surface, and the object to be sprayed (pipe) 7 is rotated around the axis by the support wheel 15 while maintaining the inside of the processing chamber 1 at the set atmosphere, and The inner surface spray gun 2 is horizontally moved by rotating a ball screw 13 by a motor 11 and moving a sliding portion meshing with the screw along a rail 14 to preheat and negatively pre-spray the pipe 7. Inner surface cleaning is performed by transfer arc processing.

After the completion of the pretreatment, the sprayed powder is supplied to the plasma jet 6 through the powder supply port 20, the powder supply pipe 8, and the powder supply path 10, while maintaining the inside of the processing vessel 1 at a predetermined reduced-pressure plasma spray atmosphere. Then, the spraying operation is performed while rotating the pipe 7 and moving the inner surface spray gun 2 horizontally.

The spray gun 2 for the inner surface directly receives radiant heat from the pipe 7 which has been heated to a high temperature by preheating, negative transfer arc processing and thermal spraying. Some of the components of the inner surface spray gun 2 are directly in contact with the high-temperature plasma jet 6. Therefore, each component of the inner surface spray gun 2 is water-cooled to prevent deformation, burning and the like. This water cooling structure is performed by a cooling water supply port 18 and a cooling water discharge port 19 connected to the rear part of the thermal spray gun body as shown in FIG.

In the thermal spray gun 2 for the inner surface of the present invention, a powder supply pipe 8 for supplying thermal spray powder to the plasma jet 6 and a powder supply path 10 are provided in a water-cooled thermal spray gun body. By adopting this structure, the supplied sprayed powder is not heated excessively and softened, so that a good sprayed powder supply performance can be ensured.

In the case of spraying a conductive powder on the metal material 7 to be sprayed, the powder supply pipe is provided in the main body of the spray gun, so that even if the powder is scattered in the atmosphere, the powder is supplied. Since a transfer arc is not generated between the pipe and the object to be sprayed, it is possible to prevent the powder supply pipe 8 and the powder supply path 10 from being damaged.

[0012]

As described above, when spraying the inner surface of an oil drilling pipe, a chemical reaction vessel, or the like, the spraying gun for the inner surface of the present invention can always provide good spray powder supply performance. , It is possible to improve the quality of the sprayed coating, stably maintain the amount of powder sprayed per unit time, and reduce the processing cost. Further, the maintenance cost of the spray gun for the inner surface can be reduced by extending the life of the supply pipe and the path of the spray powder, which are components of the spray gun for the inner surface.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an inner surface spraying gun of the present invention.

FIG. 3 is a longitudinal sectional view showing a conventional inner surface spraying gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing container 2 Inner surface spray gun 3 Nozzle 4 Anode 5 Cathode 6 Plasma jet 7 Object to be sprayed (pipe) 8 Powder supply pipe 9 Injector 10 Powder supply path 11 Inner surface spray gun running motor 12 Pipe rotation motor 13 Ball screw 14 Rail 15 Pipe support wheel 16 Vacuum pump 17 Vacuum pipe 18 Cooling water supply port 19 Cooling water discharge port 20 Powder supply port 21 Plasma gas supply port

Continued on the front page (72) Inventor Masamichi Koga 46-59 Ohara Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka Nippon Steel Corporation Machinery & Plant Business Department (72) Inventor Akira Ito Ohara Nakahara, Tobata-ku, Kitakyushu-shi, Fukuoka 46-59 Nippon Steel Corporation Machinery & Plant Business Department (56) References JP-A-5-92165 (JP, A) JP-A-3-193858 (JP, A) Table 2-2-5044044 (JP , A) (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 4/12 C23C 4/16

Claims (1)

(57) [Claims] In a plasma spray gun apparatus for performing spraying on an inner surface of a pipe or the like, the inside of a processing vessel is heated.
The projectile pipe can be rotated by a rotary motor from outside the system
And a vacuum pump is provided in the processing container,
Supply passage for thermal spray powder and plasma gas and circulation of cooling water
A spray gun with a road inside
The pipe is arranged to reciprocate in the axial direction
A plasma spray gun for an inner surface, characterized in that: