JPS5848230B2 - Transfer method of resin coated steel pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for transferring resin-coated steel pipes.

Conventionally, methods of coating steel pipes with, for example, plastic have been widely used, but a method of continuously coating large-diameter steel pipes with plastic has been particularly desired from the viewpoint of improving productivity.

As is well known, large-diameter pipes are generally long, ranging from 16 inches to 60 inches in diameter, and pipe lengths ranging from 9 m to 19 doors, and when coating plastic, they must be preheated to a specified temperature and, if necessary, coated as a base material. After applying a primer, coating with semi-melting plastic using a T-die or round die, or coating with a resin by spraying powdered resin, it is cooled and manufactured into a product.

However, in the past, there was a problem that a practical steel pipe connecting device had not been developed and that the resin was insufficiently dried after being coated with resin, causing defects in the conveying rolls of the coating. was difficult.

The present inventor had previously developed a practical steel pipe coupling device, and as a result of further research to solve the above-mentioned problems, the present invention was completed.

That is, in the present invention, a dummy material is attached to the connecting steel pipe, and a conveyance roll that can move up and down separately is interposed between the conveyance rolls, and when starting the coating work, the lift roll is held in the raised position. The resin coating operation is then carried out via lifting rolls.

In resin coating, regardless of whether the T-die method, round die method, or powder coating method is used, the gap between the steel pipe to be treated and the die or coating machine must be kept constant in order to ensure uniformity of the resin coating thickness.

However, in order to prevent the transport rolls from damaging the resin immediately after coating, the distance between the transport rolls must be increased, and as a result, in the case of large-diameter pipes, the tip of the steel pipe may sag due to the pipe's own weight, making it difficult to maintain uniform coating thickness. There is a risk of it being missing.

On the other hand, when the interval between the conveyance rolls is made small, the conveyance rolls cause scratches on the resin immediately after coating, so applying the resin coating via the above-mentioned lifting rolls is effective in solving the above-mentioned problems at the same time.

Moreover, in the present invention, since the resin coating is started after placing the dummy material, it is possible to determine the length of the dummy material that is sufficient for the resin to dry completely, and therefore, it is possible to prevent the coating of the product steel pipe from being scratched by the conveyor roll. This is effective in ensuring quality as it prevents the occurrence of

Hereinafter, an example of coating a large diameter pipe with plastic according to the present invention will be described in detail with reference to the drawings.

In FIG. 1, a connecting steel pipe 21 (in the figure, for convenience of explanation, only one steel pipe is shown), in which a plurality of steel pipes are connected by a connecting device 23, has a dummy member 20-
1, 20-2 is installed.

The connecting steel pipe 21 attached with the dummy members 20-1 and 20-2 in this way is transferred in the direction of the arrow shown in the figure while being rotated by the conveying roller 15, and is placed in the heating furnace 11 for about 20 minutes.
The outer surface of the connected steel pipe 21 is heated to 00° C., coated with a base agent by the primer coating device 16, coated with adhesive by the adhesive coating device 17, and transferred while rotating the semi-molten plastic strip by the T-die device 10. After being coated in a threaded manner, it is air-cooled by an air cooling device 12 and water-cooled by a water cooling device 13 to complete the resin coating.

In this case, in the method of the present invention, the tip of the dummy member 20-1 attached to the tip of the connecting steel pipe 21 passes through the conveying roller 15-1 located at the water cooling device 13, and the dummy member 20-1 When the rear end (i.e., the tip of the connecting steel pipe 21) reaches the primer coating device 16, the opening roll 1
4 is lowered to prevent the connecting steel pipe 21 following the dummy member 20-1 from contacting the elevator shaft 14.

At this time, the tip of the dummy member 20-1 is
Supported by 5-1.

At this point, the primer application device 16 starts applying the base material.

Next, when the tip of the connecting steel pipe 21 reaches the adhesive applicator 17, adhesive application is started.

When the tip of the connecting steel pipe 21 reaches the 1'' die device, coating with the semi-molten plastic strip is started.

In this way, the coating operation continues up to the rear end of the connecting steel pipe 21.

Then, when the rear end of the connecting steel pipe 21 (the tip of the dummy member 20-2) reaches the primer coating device 16, adhesive coating device 17, and T-die device 10, each coating or coating is stopped. .

The tip of the dummy material 20-2 enters the water cooling device 13, and before the rear end passes the conveyance roller 15-2 in front of the primer coating device 16, the lifting roll 14 is raised to remove the dummy material 202. Transport with support.

FIG. 2 shows an embodiment of the pond of the present invention using a powder coating method.

Although it is almost the same as the case in FIG. 1, the connecting steel pipe 21 is preheated to about 300°C in a heating furnace 11-2, coated with a base agent in a primer coating device 16-2, and powdered in a powder coating machine 18. The body resin is coated, the coating is cured in a post-heating furnace 19, and then cooled in a water cooling device 13.

In this case, the non-contact zone of the connecting steel pipe 21 is the conveyor roll 1
5-2 to the conveyor roll 15-1.

Therefore, the length of dummy members 20-1 and 20-2 is 1
It is necessary that the length be longer than the length between 5-2 and 15-1.

(However, in this case, the two elevator rolls 14 are raised and lowered at the same time, and if the two elevator rolls are operated individually, the length may be shorter than this.

) In this case, the operation of the lifting roll 14 is performed using the dummy member 20-
1 passes the conveyance roller 15-1 and the rear end reaches the primer coating device 16-2, the lifting roll 14 is lowered to be in a non-contact state with the subsequent connecting steel pipe 21.

Then, before the tip of the dummy member 20-2 passes the conveyance roll 15-1 and the rear end passes the conveyance roll 15-2, the lifting roll 14 is raised and the dummy member 20-2
Transport while supporting.

Although the same steel pipe as the steel pipe 21 can be used for the dummy member 20, it does not necessarily have to be a steel pipe when a desired length and diameter can be provided, and of course this does not depart from the scope of the present invention.

As described above, according to the present invention, it is possible to continuously coat a long dog-diameter steel pipe with a resin, and the industrial effect is great.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the present invention, and FIG. 2 is an explanatory diagram of an embodiment of the pond of the present invention. 10...T-die device, 11...Heating furnace, 14...4 descending roll, 16...Primer coating device, 17 Adhesive coating device, 20・・・・・・
・Dummy part, 21...Steel pipe.

Claims (1)

[Claims] 1 A plurality of steel pipes are connected with a connecting device to form a connected steel pipe, and a dummy material is attached to the tip and rear end of the connected steel pipe, and the pipe is transferred in the axial direction and installed near the front and rear of the resin coating device. The dummy member is supported while the dummy member passes by the lifting roll, and the lifting roll is lowered while the steel pipe portion whose outer surface is coated with adhesive or resin passes, and the lifting roll and the steel pipe are lowered. A method for transferring a resin-coated steel pipe, characterized by transferring the resin-coated steel pipe in a non-contact state.