JPH05200723A - Manufacturing method of composite pipe - Google Patents

Abstract

PURPOSE:To easily produce a composite pipe in low cost by applying resin lining to a Hume concrete pipe so as to enhance the bonding strength of the resin lining layer and the Hume concrete pipe without generating a problem such as the cracking of the resin lining layer. CONSTITUTION:In the inner surface finish process in the centrifugal molding of a reinforced concrete pipe using centrifugal, the inner surface of the concrete pipe is ground to uniformize the inner diameter thereof and washed with water to age the concrete pipe. A resin becoming 20% or more in its elongation capacity at 10 deg.C or higher is supplied to the inner surface of the obtained concrete pipe under rotation to be cured. The generation of a laitance layer can be prevented by the almost same process as a conventional inner surface finish method without applying special inner surface finish bringing about an increase in cost in order to remove a fragile laitance layer at the time of the centrifugal molding of a Hume concrete pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a composite pipe, and more particularly, to an improved method for producing a composite pipe excellent in chemical resistance and inner surface smoothness by applying a resin lining to the inner surface of the composite pipe. Regarding

[0002]

2. Description of the Related Art Conventionally, a composite pipe in which a polyurethane resin is supplied into a rotating concrete pipe and the inner surface of the concrete pipe is lined with the polyurethane resin has already been commercially available.

This composite pipe is a reinforced concrete pipe manufactured by a conventional method (centrifugal force forming, casting, immediate release,
Although it is manufactured by roll rolling, etc., resin lining has been applied, but in the case of reinforced concrete pipe (fume pipe) by centrifugal molding, due to the inner layer's laitance layer,
Adhesive strength between the resin lining layer and the fume tube cannot be sufficiently obtained.

That is, in the inner surface finishing step during the production of a normal fume tube, after the predetermined compaction time is over, the water squeezed out by centrifugal force is removed, and the inner surface is shaved with a round bar or the like to adjust the inner diameter to a predetermined inner diameter. Then, a kneading mortar of a predetermined composition is added to smooth the inner surface. Then, finally, after the rotation is reduced to a low speed, it is general to finish by brushing.

However, in such a method, after curing, an extremely fragile leitance layer is formed on the surface of the inner surface of the fume tube, which impedes the adhesive force of the lining layer when the inner surface is resin-lined.

Therefore, the conventional composite pipe has a drawback that the resin lining is easily peeled off during processing such as cutting pipe and perforation at the time of its construction.

Therefore, a method has been proposed in which the polymer cementitious material is applied and cured on the inner surface of the fume tube in the inner surface finishing step during the production of the fume tube, and then the resin lining is applied (Japanese Patent Application No. 63-249924). ).

[0008]

As described above, in a composite pipe in which the inner surface of the fume pipe is simply resin-lined, the adhesion strength between the fume pipe and the resin lining layer is insufficient. The resin lining layer is easily peeled off during pipe and perforation processing. Therefore, when such a conventional composite pipe is constructed, it is necessary to repair the peeled resin lining layer.

On the other hand, in the method of applying and hardening the polymer cementitious material in the inner surface finishing step during the production of the fume tube, the number of work steps increases and the material cost rises in the finishing step during the production of the fume tube. There is a drawback that is not preferable.

By the way, when the elongation ability of the polyurethane resin used in the conventional composite pipe was measured, it was found that the elongation ability at 20 ° C. was as small as about 2%. Since the conventional polyurethane resin having a small elongation ability is not flexible, the lining layer is likely to be cracked due to an impact applied during the handling of the composite pipe during transportation or laying. Due to the difference in the coefficient of thermal expansion between the fume tube and the concrete, the difference in the change in length between the fume tube and the lining layer that occurs when the temperature changes causes the resin to be easily separated from the inner surface of the fume tube.

That is, the coefficient of thermal expansion of resin is generally 10 to 20 times that of concrete. Therefore, when the temperature changes, the difference in the amount of thermal expansion between the two causes the lining layer to peel off or cracks in the lining layer. It is easy to occur.

Here, the elongation ability of the resin means an elongation rate at the time of breaking the resin when a tensile load is applied.

The present invention solves the above-mentioned problems of the prior art and is a composite pipe having a resin lining on the inner surface of a fume pipe, which has a high adhesive strength between the resin lining layer and the fume pipe, and has It is an object of the present invention to provide a composite pipe manufacturing method capable of easily and inexpensively manufacturing a composite pipe without problems such as cracking.

[0014]

The method for producing a composite pipe according to the present invention is a method of supplying a resin to the inner surface of a concrete reinforced concrete pipe while rotating the centrifugal reinforced concrete pipe to cure the resin, so that the resin is applied to the inner surface of the concrete pipe. In the method for producing a composite pipe having a lining, in the inner surface finishing step in centrifugal molding of the centrifugal force reinforced concrete pipe, after removing the inner surface to align the inner diameters, the inner surface of the concrete pipe is washed with water, and then After curing, a resin whose elongation ability after curing is 20% or more at -10 ° C or more is supplied to the inner surface of the concrete pipe.

That is, the inventors of the present invention, in the inner surface finishing step in manufacturing the fume pipe described above, wash the inner surface with water after finishing with a round bar or the like, so that the laitance layer disappears and a predetermined smooth inner surface is obtained. I found that I can be. Further, while rotating the fume tube manufactured in this way by a centrifugal molding machine (rotating around the tube axis), a resin material whose elongation ability after curing is 20% or more at -10 ° C or more is applied to the inner surface of the fume tube. It has been found that the lining layer can be formed without any problem such as cracking by lining it with the above-mentioned material, and the present invention has been completed.

In the present invention, the elongation ability of the resin means the elongation rate at the time of breaking the resin when a tensile load is applied.

The present invention will be described in detail below.

In the present invention, first, a centrifugal force reinforced concrete pipe (hereinafter referred to as “fume pipe”) is centrifugally molded, and then water squeezed to the inner surface of the fume pipe is removed in the inner surface finishing step, and further, In accordance with a conventional method, the inner surface of the fume tube is washed with water after the inner surface of the fume tube is cleaned by removing the sludge and the protruding coarse aggregate on the inner surface by grinding the inner surface with a round bar or the like.

The washing method is not particularly limited, and for example, the rotation of the fume tube may be stopped and the inside may be washed with water.

After performing such centrifugal molding, accelerated curing such as steam curing is performed according to a conventional method.

The process for making the inner diameters of the fume tubes uniform is not limited to the method using a round bar, and other methods may be used. Further, the curing does not necessarily have to be the accelerated curing.

After predetermined curing, while rotating the obtained fume tube, a resin is lined by supplying a resin to the inner wall of the fume tube and curing the resin. in this case,
The resin may be atomized and supplied by a spray gun,
In addition, as shown in FIGS. 1A to 1E, various nozzles 1A, 1B, 1C, 1D, and 1E having nozzle holes 2A, 2B, 2C, 2D, and 2E of various shapes are used to form a liquid. May be supplied.

In the present invention, the resin is −10 ° C.
The elongation ability in the above is 20% or more, preferably 25 to
Use 40%. In order to secure the elongation ability of 20% or more at -10 ° C or higher, it is impossible to use the epoxy resin or the polyester resin. In contrast, SBR
(Styrene butadiene rubber), NBR (acrylonitrile butadiene rubber), polyethylene, polyurethane, and other resins can be prepared by appropriately selecting their composition.
Has elongation ability of 20% or more even at a low temperature of 10 ° C,
A highly flexible resin can be obtained. Since these resins are rich in chemical resistance and have excellent surface smoothness,
In the present invention, it is preferable to use any one kind or two or more kinds of SBR, NBR, polyethylene and polyurethane. The polyurethane resin is preferably a solventless type.

In the present invention, the lining layer made of such a resin is usually 1.0 to 3.0 mm, though it varies depending on the size of the fume tube and the use of the composite tube.
It is formed to a thickness of about a certain degree.

Prior to forming the resin lining,
A polymer cement layer may be formed on the inner surface of the fume tube, but in the present invention, a layer for improving the adhesiveness such as a polymer cement layer is not particularly formed between the fume tube and the resin lining. It is possible to secure sufficient adhesion strength.

[0026]

As described above, the fume tube is usually formed by applying centrifugal force to form a fragile thin layer with a large amount of laitance on the very inner surface of the tube. Therefore, when the inner surface of the fume tube is lined with an organic material such as a resin or after the adhesive primer is applied, the adhesion is insufficient at the weak latance layer portion, so that the resin lining layer is easily peeled off.

On the other hand, according to the method of the present invention, in the inner surface finishing step at the time of forming the fume tube, after the finishing treatment with a round bar or the like which is usually performed, a water washing finish is carried out, so that the weak laitance layer on the inner surface is formed. The formation of a fume tube is obtained which, after curing, can be firmly adhered to the lining layer after curing. That is, in the present invention, after finishing with a round bar or the like, the inner surface of the fume tube is washed with water, so that the fragile thin layer with a large amount of leitance is removed. As described above, the resin lined after directly applying the lining or the adhesive primer to the inner surface of the fume tube having no fragile thin layer firmly adheres to and integrates with the fume tube.

Further, in the present invention, as the lining resin, a resin having an extremely large elongation ability such that the elongation ability after curing is 20% or more at −10 ° C. or more is used. Since this resin is highly flexible, it has a significantly high resistance to cracking and there is no risk of cracking due to impact or the like. Moreover, the flexibility of the resin can compensate for the difference in the length change between the fume tube and the lining resin due to the difference in the coefficient of thermal expansion between the fume tube and the lining resin, and peeling and cracking of the lining layer are effective. To be prevented.

[0029]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 In centrifugal molding of a fume tube, in the final step of finishing the inner surface, the water squeezed to the inner surface is rotated at a high speed (for example, centrifugal force of 30 g (gravitational acceleration)). After removing it, shave the concrete with a round bar,
After adjusting so as to have a predetermined inner diameter, the rotation was stopped, the inside was washed with water, and as it was, accelerated curing such as steam curing was performed according to a conventional method to obtain a fume tube having the following size.

Hume pipe size Nominal diameter = 250 mm Effective length = 2000 mm Wall thickness = 28 mm Next, a polyurethane resin (solventless type) having an elongation ability of 25% at −10 ° C. was used as the lining resin on the inner surface. Fume tube with centrifugal force molding machine 5-2
While rotating at a rotation speed of about 0 g (g: gravitational acceleration), the spray gun was moved in the tube axis direction to supply the atomized resin to the inner surface of the fume tube.

Thus, a polyurethane resin lining layer having a thickness of 1 mm was formed.

The following tests were conducted on the obtained composite pipe, and the results are shown in Table 1.

Adhesion test: An adhesion test method according to the Kenken system was performed, and the adhesion test area was set to 5 × 5 cm. The attachment jig used was one that was processed according to the curvature of the inner surface of the fume tube.

Cold / heat cycle test: test temperature = −10 ° C.
-+ 60 ° C. Test method = repetition of heating and cooling Test cycle = 2 cycles / day Comparative Example 1 In Example 1, when centrifugally forming a fume tube, after compaction by a predetermined centrifugal force, water squeezed to the inner surface was used. After removing it, scraping the inner surface with a round bar and adjusting it to a specified inner diameter, then add kneading mortar to finish the inner surface evenly, finally reduce the rotation to a low speed and finish with brushing, and then the fume tube of the same size Got

Thereafter, this fume tube was subjected to resin lining in the same manner as in Example 1, and the same test results are shown in Table 1.

Comparative Example 2 A composite pipe was produced in the same manner as in Example 1 except that the lining resin having an elongation ability at −10 ° C. of 15% was used, and the same test results are shown in Table 1. It was

Comparative Example 3 In Comparative Example 1, prior to forming the resin lining,
A composite pipe was manufactured in the same manner except that a polymer cement layer was formed on the inner surface of the fume pipe, and the same test results are shown in Table 1.

Comparative Example 4 A composite pipe was produced in the same manner as in Comparative Example 1 except that the lining resin having an elongation ability at 20 ° C. of 2% was used, and the same test results are shown in Table 1. ..

[0040]

[Table 1]

The following is clear from Table 1. That is,
In the composite pipe obtained in Example 1, since the lining resin has a large elongation ability and is highly flexible, there is no abnormality even when it is repeatedly subjected to cold heat. Further, since the fume tube does not have a weak latance layer on the inner surface, the resin lining layer and the fume tube are firmly attached to each other.

On the other hand, in Comparative Example 1, the adhesive strength of the resin lining layer is low due to the leitance layer on the inner surface of the fume tube. Further, in Comparative Example 2, the resin lining layer has high adhesion strength, but the resin has poor elongation ability, so that the results of the cold heat repetition test are poor. In Comparative Example 3, good results were obtained by using a resin having a large elongation ability and by forming the polymer cement layer, but in this case, a step for forming the polymer cement layer is required. ..
Further, in Comparative Example 4, since the resin has poor elongation ability and the presence of the leitance layer, good results cannot be obtained in both the adhesion test and the cold heat repetition test.

[0043]

As described above in detail, according to the method for manufacturing a composite pipe of the present invention, a special inner surface finish that causes a cost increase is removed in order to remove a weak leitance layer during centrifugal molding of a fume pipe. It is possible to prevent the generation of the laitance layer by performing the steps substantially the same as the conventional inner surface finishing method without performing the steps. Therefore, the resin lining can be firmly attached and integrated to the inner surface of the fume tube.

Further, since the resin lining layer thus formed has high adhesion strength to the inner surface of the fume tube and is highly flexible, it can be handled at the time of construction or under severe usage conditions. Also does not peel or crack.

According to the present invention, a composite pipe having excellent chemical resistance and smoothness on the inner surface, which is useful for various purposes, and which is remarkably excellent in handleability, workability and durability, can be easily manufactured at low cost. be able to.

[Brief description of drawings]

FIG. 1 is a front view showing a specific example of a nozzle used for supplying resin in the present invention.

[Explanation of symbols]

 1A, 1B, 1C, 1D, 1E Nozzle 2A, 2B, 2C, 2D, 2E Nozzle hole 3 Resin

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Claims (1)

[Claims] 1. A method for producing a composite pipe in which a resin lining is applied to the inner surface of the concrete pipe by supplying a resin to the inner surface of the concrete pipe to cure it while rotating the centrifugal reinforced concrete pipe, In the inner surface finishing step in the centrifugal molding of the centrifugal force reinforced concrete pipe, after removing the inner surface to make the inner diameter uniform, the inner surface of the concrete pipe is washed with water, and then cured, and then the inner surface of the concrete pipe is cured. A method for producing a composite pipe, which comprises supplying a resin having an elongation ability of 20% or more at -10 ° C or more.