JPH1076191A - Powder coating method for inside surface of steel pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody a powder coating method for the inside surface of a steel pipe which is capable of improving working environment, forming coating films having high accuracy and improving cost effectiveness and is applicable to steel pipes of various sizes and shapes. SOLUTION: A gun supporting and moving device 18 is disposed at one end of the steel pipe 10 having the inside surface to be coated. A powder coating machine 22 is connected to the other end of a hollow rod 12 which is mounted adjustably in height at the device 18 and is provided with a coating material gun 11 at the front end. A suction fan is connected via a suction pipe to the other end of the steel pipe 10 and thereafter, the powder coating material forcibly fed from the powder coating machine 22 is ejected out of the coating material gun 11 and is adhered to the inside surface of the steel pipe while the suspended coating material in the steel pipe is sucked by the suction fan and while the coating material gun 11 is moved by the gun supporting and moving device 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating method for the inner surface of a steel pipe applied to a ship, a chemical plant, a petroleum refining plant and the like.

[0002]

2. Description of the Related Art A conventional powder coating on the inner surface of a steel pipe will be described with reference to FIG. In FIG. 5, 1 is a steel pipe to be coated, 2 is a rotating support roller, 3 is a heating burner, 4 is a paint rod, 5 is a blowout hole, 6
Is a paint hose and 7 is a valve.

In the above description, when the steel pipe 1 is rotated by the rotation supporting roller 2 and heated by the plurality of heating burners 3 installed at the lower part of the steel pipe 1, the steel pipe 1 is heated to a specified temperature. , Paint rod 4 from one end of steel pipe 1
Is inserted. After the paint rod 4 is inserted into the steel pipe 1, the valve 7 is opened, the powder paint is pumped through the paint rod 4 via the paint hose 6 and the valve 7, and the blowout hole provided at the tip thereof is provided. 5 and is applied to the inner surface of the steel pipe 1.

Since the steel pipe 1 is heated to a predetermined temperature by the heating burner 3, the powder coating applied to the inner surface of the steel pipe 1 adheres to the inner surface of the tube and is simultaneously welded to the inner surface of the tube.

The powder coating is applied to the inner surface of the steel pipe while the tip of the coating rod 4 is moved from one end of the steel pipe 1 to the other end in the pipe length direction, and is performed over the entire length of the steel pipe 1.
When the tip of the paint rod 4 reaches the other end of the steel pipe 1, the valve 7 is closed, the heating burner 3 and the rotation support roller 2 are stopped, and the painting is completed. Note that these series of operations are performed by a plurality of workers.

[0006]

The conventional powder coating of the inner surface of a steel pipe has various problems as described below.

(1) The amount of powder paint blown out, the rotational speed of the steel pipe,
Since all factors that determine the thickness of the coating film, such as the speed of moving the paint rod, are determined by the skill of the operator, the accuracy of the coating film (thickness, unevenness) is not stable. (2) It is necessary to work in a bad environment with high temperature and a lot of dust.

(3) Correction work cannot be performed due to welding immediately after spraying. (4) Since all of the excess paint sprayed out is deposited and welded in the steel pipe, the coating film tends to be excessively thick. (5) The powder coating of this method cannot be applied to anything other than a straight pipe.

The present invention solves the above-mentioned problems by stabilizing the accuracy of the coating film, improving the working environment in the powder spraying and heating processes, and recovering and reusing surplus paint in consideration of economy and straight pipe. It is intended to provide a coating method applicable to all steel pipes such as curved pipes and branch pipes other than the above.

[0010]

According to a first aspect of the present invention, there is provided a method for coating powder on the inner surface of a steel pipe, wherein the powder is sprayed on one end of the steel pipe whose inner surface is coated with a powder coating charged with static electricity at its tip. A gun support moving device equipped with a hollow bar provided with a gun is provided, a powder coating machine is connected to the other end of the hollow bar, and the position of the paint gun in the inner diameter direction of the steel pipe of the paint gun is connected by the gun support moving device. Then, after connecting a suction fan to the other end of the steel pipe via a suction pipe, while driving the suction fan to suck the powder paint floating inside the steel pipe, the hollow rod is moved by the gun supporting and moving device. While moving the paint gun in the steel pipe at a predetermined speed in the axial direction thereof through the hollow rod, a predetermined flow rate of the powder paint pumped from the powder coating machine is ejected from the paint gun from the paint gun to form the steel pipe. Attached to the inner surface, powder coating the specified inner surface of the steel pipe It is characterized in that the steel pipe is heated to after applying completing baked powder coating.

In the present invention, the distance between the paint gun and the inner surface of the steel pipe, the moving speed of the paint gun, the flow rate of the powder paint ejected from the paint gun, and the suction flow rate of the floating paint are factors that determine the accuracy of the paint film. And the like can be easily controlled, so that a highly accurate coating film can be formed.

Further, since the powder paint is applied to the inner surface of the steel pipe by the paint gun while the powder paint floating in the steel pipe is sucked by a suction fan, the powder paint is prevented from scattering to the outside of the steel pipe. The working environment can be improved, and the economic efficiency can be improved by recovering the powder coating material.

Further, since the height of the paint gun installation position can be adjusted by the gun supporting and moving device, various dimensions and
It becomes possible to cope with a steel pipe having a shape with one device.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A powder coating apparatus for an inner surface of a steel pipe according to an embodiment of the present invention will be described with reference to FIGS. The present embodiment shown in FIGS. 1 to 4 is a case where the present embodiment is applied to powder coating of the inner surface of the branched steel pipe 10.

The powder coating apparatus according to the present embodiment shown in FIGS. 1 to 4 is, as shown in FIG. 1, an automatic coating apparatus 13 provided at one end of a branch steel pipe 10 to be coated. A suction fan 15 connected to the other end of the branched steel pipe 10 via a suction pipe 14, and a blind cover 1 provided at an opening of the branch pipe;
6.

As shown in FIGS. 1 and 2, an automatic coating apparatus 13 forming a powder coating apparatus according to the present embodiment is provided with a powder coating which is inserted into a branched steel pipe 1 and has a tip charged with static electricity. A paint gun guiding hollow rod 12 provided with an all-circumferential spray gun 11 to be ejected, a gun supporting / moving device 18 for supporting and moving the hollow rod 12, and a steel pipe 10 with a branch connected to the gun supporting / moving device 18 It is formed by a fixed ring 17 provided at one end and a powder coating machine 22 connected to the rear end of the hollow rod 12.

As shown in FIG. 2, the gun supporting and moving device 18 forming the automatic coating device 13 has a slide beam 30 and a lower slide beam 31 each having one end connected to the fixed ring 17, respectively. Slide mechanism 3 through which slides 30, 31 penetrate and slide the slide beams 30, 31
3. a column 32 connected to the other end of each of the slide beams 30, 31; a driving roller 19 disposed on the column 32 to move the paint gun guiding hollow rod 12 in the pipe length direction (axial direction of the steel pipe 10); It is formed by a roller driving motor 20 directly connected to the driving roller 19 and a controller 21 connected to the motor by an electric wire.

The details of the slide mechanism 33 forming the above-mentioned gun supporting and moving device 18 will be described with reference to FIG. The slide mechanism 33 shown in FIG.
An adjusting hole 28 and a slide hole 29 are provided. The hollow rod support bar 27 is connected to the paint gun guiding hollow rod 12, and the slide hole 29 is penetrated by the upper slide beam 30 and the lower slide beam 31. I have. The adjusting hole 28 is for adjusting the paint gun 11 to an arbitrary position on the steel pipe 10, and a plurality of the adjusting holes 28 are provided in accordance with the inner diameter of the steel pipe 10.

Fixed ring 1 forming automatic coating device 13
Details of 7 will be described with reference to FIG. 4 includes a support ring 17a, six support pins 23 provided at equal intervals on the support ring 17a, and three tubes connected to the support ring 17a by the support pins 23, respectively. End support pawls 24 and three levers 24a, and six connecting bars 2 connected between the respective tube end support pawls 24 and levers 24a
5, and a piston rod is connected to each continuous bar 25, and a cylinder is formed by a driving cylinder 26 connected to the support ring 17 a and transmitting power to the support claw 24.

Next, the procedure for performing powder coating on the inner surface of a steel pipe using the powder coating apparatus according to the present embodiment will be described below. In this construction, first, a painting preparation work is necessary. In this preparation work, an automatic painting device 13 is attached to one end of the steel pipe 10, a suction fan 15 is attached to the other end via a suction pipe 14, and other opening ends are provided. A blind lid 16 is attached to the open end of the branch pipe.

When the automatic coating device 13 is attached to one end of the steel pipe 10, first, a fixed ring 17 is disposed at one end of the steel pipe 10 so as to surround the steel pipe 10. The fixed ring 17 has a larger diameter than the maximum outer diameter (normally 800 mm) of the steel pipe to be coated. After the arrangement of the fixed ring 17, air is supplied from an air source (not shown) to the driving cylinder 26 shown in FIG. 4A via a valve to extend the piston rod as shown in FIG. 4B. .

When the piston rod of the driving cylinder 26 is extended, the connecting bar 25 moves to rotate the pipe end supporting claw 24 with the fulcrum pin 23 as a fulcrum.
Is held in contact with the outer periphery of the. The piston rod of the driving cylinder 26 extends in accordance with the outer diameter of the steel pipe 10 (that is, until the support claw 24 comes into contact with the steel pipe 10). Fixed to

Next, the paint gun 11 and the guide hollow rod 12
Is adjusted to a predetermined position in the inner diameter direction of the steel pipe 10 (the distance between the coating gun 11 and the inner wall of the pipe is determined by the coating ability of the coating gun 11). This is done by selecting the adjustment hole 28 of the slide mechanism 33 shown in FIG.
7 is performed. When the diameter of the steel pipe 10 changes, the selection of the adjustment hole 28 is changed to cope with the change.

The painting preparation work is completed as described above, and this work is started. In this work, first, the suction fan 15 provided at the other end of the steel pipe 1 is operated, and the specified wind speed (experimental test) is set at the inlet of the suction pipe 14. Is adjusted by a wind speed control valve (not shown) so that the result is about 3 m / s).

Next, the powder coating machine 22 is operated to adjust the flow rate, the conveying pressure and the applied electrostatic voltage (in the experimental results, the flow rate =
250 g _r / min, pressure = 2 kgf / cm ² , voltage = 80 kv), and the powder paint is ejected from the paint gun 11. At this time, the paint gun 11 ejects the powder paint while moving in the pipe length direction by the drive roller 19 driven by the motor 20, and the steel pipe 10
Apply to the inner surface of.

The moving speed of the paint gun 11 is controlled by the controller 21 to a specified speed. Most of the powder paint sprayed from the paint gun 11 is applied to and adheres to the inner surface of the steel pipe 10, but a part of the powder paint floats inside the steel pipe 10.
The floating paint is supplied to the suction fan 15 through the suction pipe 14.
Is sucked and collected.

After the powder paint is completely adhered to a predetermined location on the inner surface of the steel pipe 10, the steel pipe 10 is heated from the outer periphery thereof with a gas burner or the like, so that the powder paint is applied to the steel pipe 10.
Bake on the inside.

In the present embodiment, as described above, the factors that determine the coating accuracy in powder coating (the amount of the paint to be sprayed, the distance between the gun and the inner surface of the pipe, the blowout pressure, the applied voltage, the coating speed, the suction wind speed, etc.) Is precisely defined and controlled, so that high-precision coating can be performed automatically and efficiently, and the recovered floating paint can be reused after filtering, improving economic efficiency. And,
These effects can be realized for various steel pipes (straight pipe, curved pipe, branch pipe).

[0029]

According to the powder coating method for the inner surface of a steel pipe according to the present invention, a gun supporting and moving device is provided at one end of a steel pipe whose inner surface is to be coated, and is mounted on the same device so as to be adjustable in height, and a paint gun is mounted at the tip. Connect the powder coating machine to the other end of the hollow bar provided with
After connecting a suction fan to the other end of the steel pipe via a suction pipe, the suction fan sucked the floating paint in the steel pipe while moving the paint gun by the gun support moving device, and was fed from the powder coating apparatus while moving the paint gun. By spraying powder paint from the paint gun and attaching it to the inner surface of the steel pipe,
High-precision coating film formation by appropriate control of factors that determine coating film accuracy, improvement of work environment by suction of floating paint, improvement of economic efficiency, adjustment of paint gun installation height to steel pipes of various sizes and shapes Applicable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a powder coating apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the automatic coating apparatus according to the embodiment.

FIG. 3 is an explanatory diagram of a slide mechanism according to the embodiment.

FIG. 4 is an explanatory view of a fixed ring according to the embodiment;
(A) is an explanatory view of a state where an end pipe supporting claw is opened, and (b) is an explanatory view of a state where a steel pipe is held.

FIG. 5 is an explanatory diagram of a conventional method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 Branched steel pipe 11 Full-circle spray paint gun 12 Hollow rod for guiding paint gun 13 Automatic coating device 14 Suction tube 15 Suction fan 16 Blind lid 17 Fixed ring 18 Gun support and moving device 19 Drive roller 20 Roller drive motor 21 Controller 22 Powder coating machine

Claims (1)

[Claims] 1. A gun supporting and moving device having a hollow rod provided at one end of a steel pipe whose inner surface is coated with a paint gun for ejecting an electrostatically charged powder paint at its tip,
A powder coating machine was connected to the other end of the hollow rod, the position of the paint gun in the inner diameter direction of the steel pipe was adjusted by the gun support moving device, and a suction fan was connected to the other end of the steel pipe via a suction pipe. Then, the suction fan is driven to suck the powder coating material floating inside the steel pipe while moving the coating gun at a predetermined speed in the axial direction of the steel pipe in the steel pipe through the hollow rod by the gun supporting and moving device. A predetermined amount of powder paint, which is fed from the powder coating machine through the hollow rod, is ejected from the paint gun and adheres to the inner surface of the steel pipe. And baking the powder coating by heating the inner surface of the steel pipe.