JPS591571B2 - Method for forming a protective film on the inner surface of a tube - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for forming a protective film on the inner surface of a tube.

As a method for regenerating existing buried pipes (hereinafter referred to as pipes to be regenerated),
A construction method has been proposed in which a flexible synthetic resin pipe is coated on the inner surface of a recycled pipe that has been cleaned.

In this type of regeneration method, as a means for inserting a flexible synthetic resin pipe into the regenerated pipe, the regenerated pipe a is used as shown in Figure 1.
Insert the synthetic resin pipe b directly into the method or second method
As shown in the figure, a method may be adopted in which the synthetic resin tube b is inserted in a vertically folded state utilizing its flexibility, and then fluid is passed inside to restore it to its original shape. However, in the former method, insertion is difficult unless the fit between the inner and outer tubes is made tight, so it is necessary to insert the inner and outer tubes a and b after insertion.
A gap c is created between them, and this gap must be filled with cement or the like, and this filling operation is extremely complicated and poses a major problem in workability. Also, in the latter method, the outer tube a
When the inner tube b is drawn in, a large frictional resistance is generated between the inner and outer tubes a and b, and this frictional resistance
The layer thickness is increased by the presence of a pre-formed adhesive layer on either side thereof for the purpose of gluing. However, this latter method requires a large pulling force to pull in the inner pipe b, and the connection between the drawing rope and the inner pipe b may break and the rope comes off, or due to large frictional resistance,
There is a risk that the inner tube b is twisted within the outer tube a, effectively partially blocking the internal space, and causing problems such as the inner tube b not being able to be restored to its original state despite the supply of pressurized fluid to the inside. This latter method also had a major problem in workability. Recently, a method has been proposed in which the tube is inserted into the pipe while being reversed using fluid pressure. Since the two insertion steps were performed as separate operations, work efficiency was not very high. The present invention was made for the purpose of providing a method for forming a protective film on the inner surface of a pipe, which is useful when applied to this type of reclamation method.
The explanation will be as follows based on the figures and FIG.

In one embodiment of the construction method of the present invention shown in FIG. 3, a flexible lining tube 2 made of rubber or synthetic resin for adhering to the inner surface of the regenerated pipe 1 is wound around a drum 3. It is prepared in the condition that it is prepared.

It may be advantageous for this drum 3 to be equipped with a braking device 4. The tube 2 wound around the drum 3 may be of long length, or may be of a fixed length approximately 5 to 10 m longer than the tube to be regenerated 1.

When using a fixed-length naube 2, a rope (not shown) of approximately the same length as the tube 2 should be tied to the end of the tube 2, and the end of the rope should be tied to the drum 3. is preferred. During construction, a sufficient amount of adhesive 5 necessary and sufficient to bond the naube 2 along the entire length of the regenerated tube 1 is stored inside the tube 2 through the opening at its tip, and then the tip of the naube 2 is bonded to the card. After passing through the rolls 6 and squeeze rolls 7, 7, it is externally fitted onto the starting end of the pipe to be regenerated 1, and this external fitting part 2a is tightened with a clamp 8.

Next, when the inside of the regenerated tube 1 is reduced in pressure by a pressure reducing device (not shown) connected to the terminal end of the regenerated tube 1, the pressure difference between the inside and outside of the tube causes the tube 2 to become regenerated as shown in FIG. tube 1
It is inverted and sucked inside.

Also, in parallel with this reversal suction, on the inner surface of tube 2,
A predetermined amount of adhesive is applied under the control of the application amount by the squeezing roll 7.7, so that the tube 2 is adhered to the inner surface of the tube 1 at the same time as it is turned over. By continuing the reverse suction adhesion of the tube 2 under such reduced pressure operation, the tube 2 is attached to the inner surface of the regenerated tube 1.
Can form the lining of

In the present invention, the tube can be lined on the inner surface of the tube while simultaneously applying adhesive to the tube and reversing and inserting the tube in parallel, so that these steps can be performed individually. The work becomes much more efficient than in the case of conventional methods, contributing to simplifying the work process and improving work efficiency. Furthermore, since the tube is inverted and suctioned into the pipe by depressurization, it is not necessary to install a pressurizing housing as is the case when applying a pressurizing means.

For example, if a pressurized housing is installed and emphasis is placed on airtightness, when the tube is drawn into the pressurized housing, the adhesive applied to the inner surface of the tube may be squeezed out, resulting in an insufficient amount of coating, leading to poor adhesion. On the other hand, if emphasis is placed on the amount of adhesive applied, the airtightness will be compromised, making it impossible to maintain the pressure inside the pressurized housing at a predetermined pressure, which will hinder the inversion and insertion of the tube. By applying pressure reduction means, such problems can be eliminated. In the recycling method of the present invention, the tube has an outer diameter approximately equal to the inner diameter of the pipe to be recycled, and is made of flexible synthetic resin such as polyethylene, polyvinyl chloride, polypropylene, natural rubber, or synthetic rubber. Among them, they are selectively used depending on the type of pipe to be regenerated.

In the present invention, after the tube is inverted and inserted into the tube as described above, heated air or steam is supplied under pressure into the tube to soften and swell the tube, and after it is brought into close contact with the inner surface of the tube, It may be solidified by cooling (including air cooling).

The protective film forming method according to the present invention can be applied not only to a method for recycling existing buried pipes, but also to forming a protective film on the inner surface of a new pipe.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing an example of the conventional reclamation method, Figure 3 is a vertical cross-sectional view of the main part showing the implementation status of the regeneration method of the present invention, and Figure 4 is a diagram showing an example of the regeneration method of the present invention. It is an explanatory diagram showing the situation when the tube is inserted in reverse. In the figure, 1 is the pipe to be reproduced, 2 is the nayub, 3 is the drum,
4 is a braking device, 5 is an adhesive, 6 is a guide roll, 7 is a squeeze roll, and 8 is a clamp.

Claims (1)

[Claims] 1 A sufficient amount of adhesive necessary and sufficient to bond the tube along the entire length of the tube is stored in advance in a lining tube fixed to the starting end of the tube at the tip, and this tube is squeezed with a squeeze roll. A method for forming a protective film on the inner surface of a tube, characterized in that the adhesive is adhered to the inner surface of the tube while being reversely suctioned from the starting end of the tube toward the terminal end by a suction action based on the reduced pressure inside the tube while adjusting the amount of adhesive applied.