JPH0148074B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating the inner surface of a metal tube or the like having a flange with a resin.

Conventionally, there is a method for coating the inner surface of a steel pipe with resin by feeding resin powder together with air into a heated steel pipe and welding it. Because it protrudes perpendicularly to the inner surface of the tube, it was not possible to weld the coating to the inner surface of the tube to a uniform thickness. Therefore, after coating the inner surface of the tube, resin powder was sprayed onto the flange surface using a spray gun, but this required two steps and was difficult and time-consuming to coat the flange surface with a uniform thickness using a spray gun. It required

The present invention aims to eliminate the above-mentioned drawbacks and provide a method for coating the flange surface simultaneously with the tube inner surface.

The present invention will be explained with reference to the drawings.

The figure is an explanatory diagram showing an example of an embodiment of the present invention,
Joints 2, 2 are connected to both ends of the heated flanged steel pipe 1, and powdered resin mixed air is supplied into the steel pipe 1 through the joints 2, 2 to weld and coat the inner surface of the steel pipe 1 and the flange surface with powdered resin. It begins to form layers. The joints 2, 2 move forward and backward toward the steel pipe 1 and are supported by rotatable supports 3, 3, and one joint 2 receives powder resin mixed air from the powder supply hopper 4 and the air introduction hole 5. The other joint 2 is provided with a cyclone 6.
A suction blower 7 is connected via.

In this device, when the suction blower 7 is operated, air is sucked through the air introduction hole 5 through the cyclone 6, and powdered resin is supplied from the hopper 4 into this air flow, resulting in air mixed with powdered resin. Steel pipe 1 flows through joint 2
is supplied to Since the steel pipe 1 is heated, the powdered resin comes into contact with its inner wall, melts and adheres thereto, and forms a resin layer. The powdered resin that has passed through the steel pipe 1 is collected by a cyclone 6.

In the above apparatus, the present invention uses a joint 2 as shown in FIG.

The joint 2 is pressed against and connected to the flange 11 surface of the steel pipe 1, and the air flow path 21 of the joint 2 is expanded in the radial direction near the end surface where it connects to the flange 11, and the center of the expanded portion 22 is expanded. A core member 23 is provided. This core member 23
is fixed by a retaining rod 24 and bridges 25, 25 from the axial direction of the flow path 21. An annular flow path 26 is formed by the core member 23 between the inner peripheral surface of the enlarged portion 22 of the air flow path 21 and the outer peripheral surface of the core member 23 . When the joint 2 is connected to the flange 11, the annular flow path 26 is continuous with the annular flow path formed between the core member 23 and the flange 11 and continues into the steel pipe 1. The front surface of the joint 2 has a diameter that closes the bolt hole of the flange 11.

The core member 23 can be cooled by cooling water through the bridge 25, and powder resin is prevented from adhering to the core member 23. Also, joint 2
The outer surface is also now cooled. By using the joint 2 as described above, the powder resin mixed air flows along the flange surface in the annular flow path, and the flange surface is also coated on the inner surface of the steel pipe 1 at the same time.

The steel pipe 1 coated with molten powder resin is separated by retracting the joints 2, 2, and the coated resin is cross-linked by heating if necessary and then cooled to obtain a flanged inner-coated steel pipe.

The method for coating the inner surface of a flanged pipe according to the present invention is the method described above, in which a core member is provided in the center of the air flow path of the joint to form an annular flow path, and this annular flow path faces the flange surface. By connecting in this way, the powder resin mixed air can be attached and melted to the flange surface and the tube inner surface at the same time, and the flange surface can also be coated in a single process, making it easy to coat the flange surface. .

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing an example of an embodiment of the present invention, and FIG. 2 is a partially omitted sectional view showing an example of a joint used in the present invention. 1: Steel pipe with flange, 11: Flange, 2: Joint, 21: Air flow path, 23: Core member, 2
6: Annular channel.

Claims (1)

[Claims] 1. In a method for coating the inner surface of a tube in which a joint is connected to both ends of a heated flanged tube and powdered resin-mixed air is supplied into the tube through the joint, a core member is provided in the center of the air flow path of the joint to control the annular flow. A method for coating the inner surface of a flanged pipe, comprising forming a channel and connecting the annular channel so as to face the flange surface.