JPH10122463A - Pressure proof flexible pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a connection part to piping from being damaged by external force by embedding a reinforcing cord between an inner layer and an outer layer of a flexible cylindrical body and only in the vicinity of the periphery inside each angle protrusion, and embedding a metal ring inside each angle protrusion and in the inner layer away from the reinforcing cord. SOLUTION: A flexible cylindrical body 2 has an inner layer 6 and an outer layer 7, and a reinforcing cord 8 is embedded between both layers. At each angle protrusion 4 part, the reinforcing cord 8 is embedded along the peripheral surface, only in the vicinity of the peripheral surface. A metal ring 9 is embedded inside of each angle protrusion 4 and in the inner layer 6 away from the reinforcing cord 8. The outer layer 7 can therefore be elongated in the state of the angle protrusion 4 becoming low while the reinforcing cord 8 approaches the metal ring 9, and the inner layer 6 at the angle protrusion 4 part is also elongated along with the outer layer 7. A connection part to piping is therefore prevented from being damaged or coming off by the change of external force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-resistant flexible pipe joint for connecting pipes buried in soil or the like.

[0002]

2. Description of the Related Art Conventionally, pressure-resistant flexible pipe joints have been used for connecting pipes buried in underground soil such as roads with flexibility. This type of joint includes a flexible tubular body having flange connection portions at both ends and a plurality of ring-shaped projections formed at predetermined intervals on an intermediate outer peripheral portion, and a reinforcing cord and a flexible cord are provided in the flexible tubular body. A metal ring is buried. FIG. 5 is an enlarged sectional view showing a chevron-shaped projection of a conventional pressure-resistant flexible pipe joint. The pressure-resistant flexible pipe joint 10 includes a flexible cylinder 11 made of a flexible material such as rubber, and has a plurality of ring-shaped projections 12 formed at predetermined intervals on an outer peripheral portion thereof. A reinforcing cord 15 is embedded between the outer layer 14 and the outer circumferential surface of the flexible tubular body 11. The metal ring 1 is attached to the inner layer 13 located inside the chevron 12
6 is buried. In this example, the inner circumference of the cross section of the inner layer 13 is linear. FIG. 6 shows a conventional pressure-resistant flexible pipe joint 10.
FIG. 6 is a cross-sectional view showing, in an enlarged manner, a chevron projection 12 as in FIG. 5 in another example. Note that this example is different from the example of FIG. 5 in that the inner surface of the inner layer 13 is concave in the shape of the chevron 12 in each chevron 12.

[0003]

However, the conventional pressure-resistant flexible pipe joint described above has a problem in that when a large vibration is applied to the buried underground part due to an earthquake, traffic of a large truck, or the like, the flexible pipe joint is not provided. External forces such as expansion, contraction, bending, shearing, twisting, etc. are applied, which tends to damage or disconnect the connection with the piping.To solve this problem, design the joint with a large load-bearing design or bury it It is necessary to take measures such as providing special external protection means at the part, but any of these methods is disadvantageous in cost. Accordingly, an object of the present invention is to provide a pressure-resistant flexible pipe joint that solves such a problem.

[0004]

As a result of various studies to solve the above problems, the conventional pressure-resistant flexible pipe joint is embedded in the inner layer 13 with the metal ring 16 in contact with the reinforcing cord 15. Was found to be the main cause of not being able to adequately follow external forces. That is, for example, when an external force that extends the chevron 12 shown in FIG. 5 or 6 is applied, even if the chevron 12 attempts to expand, the reinforcing cord 15 having almost no elasticity is attached to the metal ring 16. Because it is in contact, it is locked and cannot be extended. The stress generated in such a case is generated when an external force such as bending, shearing, or twisting is applied to the flexible pipe joint.

[0005] The pressure-resistant flexible pipe joint of the present invention based on such knowledge has flange connection portions provided at both ends and a plurality of ring-shaped projections formed at predetermined intervals on an intermediate outer peripheral portion. Flexible tubular body, the flexible tubular body has an inner layer and an outer layer, and a reinforcement cord is buried between them and only in the vicinity of the outer periphery in the chevron, and each chevron is provided with a reinforcing cord. A metal ring is embedded in an inner layer that is inside and separated from the reinforcing cord. In the pressure-resistant flexible pipe joint of the present invention, since the metal ring is buried in the inner layer separated from the reinforcing cord, the elasticity of each chevron-shaped projection portion is good, and it is resistant to external forces such as expansion, contraction, bending, shearing, and twisting. Can follow flexibly. Therefore, the connection portion with the pipe is not damaged or disconnected by the external force.

[0006]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a front view showing an example of a pressure-resistant flexible pipe joint of the present invention, with a part thereof cut away. FIG. 2 is an enlarged partial cross-sectional view of the chevron. In these figures, a pressure-resistant flexible pipe joint 1 is provided with a flanged connecting portion 3 at both ends and a plurality of ring-shaped angled projections 4 formed at predetermined intervals on an intermediate outer peripheral portion.
It has. The flange connection portion 3 is fitted with a companion flange 5 for bolting the flange connection portion 3 to a pipe flange (not shown). The flexible cylinder 2 has an inner layer 6
And an outer layer 7, and a reinforcing cord 8 is buried between them, and the reinforcing cord 8 is buried only in the vicinity along the outer peripheral surface of each chevron projection 4 portion. A metal ring 9 is embedded in the inner layer 6 inside each chevron 4 and away from the reinforcing cord 8.

The inner layer 6 and the outer layer 7 constituting the flexible cylindrical body 2
For example, rubbers such as natural rubber and synthetic rubber, plastics having flexibility, and the like can be used. As the reinforcing cord 8, high-strength synthetic fibers such as polyamide and polyester can be used.
Then, the reinforcing cords 8 are sandwiched between the inner layer 6 and the outer layer 7, and they are integrally formed by a heating press or the like. Furthermore, steel wire is generally used for the metal ring 9. FIG. 3 shows an angle projection 4 when an external force is applied to the pressure-resistant flexible pipe joint.
It is a fragmentary sectional view showing the deformation state of. As can be seen from this figure, since the metal ring 9 is separated from the reinforcing cord 8, the portion of the chevron 4 is lowered while the reinforcing cord 8 approaches the metal ring 9, and the outer layer 7 can be extended. At the same time, the inner layer 6 at the chevron 4 also extends. Therefore, the distance at which the metal ring 9 separates from the reinforcing cord 8 is set to such a value that the deformation of the chevron projection 4 can be sufficiently performed.

When an external force is applied to the pressure-resistant flexible pipe joint 1 in the extension direction, each of the chevron-shaped projections 4 is extended as described above, whereby the entire pressure-resistant flexible pipe joint 1 is extended. When an external force in the compression direction is applied to the pressure-resistant flexible pipe joint 1, each chevron projection 4 is compressed, and the entire pressure-resistant flexible pipe joint 1 contracts in the longitudinal direction. Also, when an external force in the bending direction is applied to the pressure-resistant flexible pipe joint 1, each chevron projection 4 located outside the bend expands, and each chevron projection 4 located on the opposite side is compressed. The entire pressure-resistant flexible pipe joint 1 is bent. When an external force in the torsional direction is applied to the pressure-resistant flexible pipe joint 1, each of the chevron projections 4 expands in the same manner as when an external force in the elongation direction is applied. The whole twists. Further, when a shearing force is applied to the pressure-resistant flexible pipe joint 1, each chevron projection 4 located on the front side in the shearing direction expands, and each chevron projection 4 located on the opposite side is compressed, whereby:
The entire pressure-resistant flexible pipe joint 1 follows the shearing force.

[0009]

Next, using the pressure-resistant flexible pipe joint 1 of the present invention shown in FIG. 1, as shown in FIG. 4, the limit of extension of the joint in the axial direction and the limit of eccentricity in the shear direction are shown. An experiment was performed to measure For comparison, the limit of elongation and the limit of eccentricity of the conventional pressure-resistant flexible pipe joint shown in FIG. 5 were measured.
At this time, the thing of the present application and the thing of the comparative example were all the same except for the embedding position of the metal ring. Each pressure-resistant flexible pipe joint is subject to the following conditions. In FIG. 1, the inner diameter is 200 mm, the length is 500 mm, and there are three chevron projections.
m, the radius of the protrusion of the chevron is 26 mm, and the diameter of the metal ring is 13 mm. In the joint of the present invention, the distance between the center of the buried metal ring 9 and the inner surface of the pipe joint is 12.5 m.
m. The distance between the center of the metal ring 16 of the conventional pressure-resistant flexible pipe joint in FIG. 5 and the top outer surface of the chevron 12 is 12.5 mm.

Both ends of such a pressure-resistant flexible pipe joint were connected to a tester via a flange, and an elongation test shown in FIG. 4A and an eccentricity (shear) test shown in FIG. 4B were performed. The pass / fail judgment was made based on how much the pipe joint as a whole could be extended or eccentric before the stress generated in the flange portion of the pipe joint reached a predetermined value. In this example, when a 5 mm elongation occurs at the root of the flange of the pipe joint supported by the metal flange, the limit value of the temporary elongation and the limit value of the eccentricity were used. As a result, the pipe joint of the present invention has a total of 150
mm, whereas the conventional fitting was 110 mm. The allowable eccentric length was 140 mm for the pipe joint of the present invention and 105 mm for the conventional pipe joint. The shrinkage is about 70 mm for both,
There was no difference between the two. From this, it has been found that the pressure-resistant flexible pipe joint of the present invention has high reliability in that a crack is less likely to occur in its flange portion even if it is deformed to a greater extent than that of a conventional product. this is,
For example, it means that the ability to cope with a crack or a displacement in the ground in which the pipe joint is buried is high.

[0011]

According to the pressure-resistant flexible pipe joint of the present invention constructed as described above, since the metal ring is buried in the inner layer separated from the reinforcing cord, the elasticity of each chevron is good. It can flexibly follow external forces such as expansion, contraction, bending, shearing, and twisting. Therefore, the connection portion with the pipe is not damaged or disconnected due to the change of the external force.

[Brief description of the drawings]

FIG. 1 is a partially broken front view of a pressure-resistant flexible pipe joint of the present invention.

FIG. 2 is an enlarged partial cross-sectional view showing a chevron-shaped projection portion of FIG. 1;

FIG. 3 is a partial cross-sectional view showing a deformed state when an external extension force is applied to a chevron projection 4 of the pressure-resistant flexible pipe joint of FIG.

FIG. 4 is a diagram showing a state in which a load test is performed on the pressure-resistant flexible pipe joint of the present invention in the direction of expansion and contraction and the direction of eccentricity (shear).

FIG. 5 is an enlarged partial cross-sectional view showing a chevron projection in a conventional pressure-resistant flexible pipe joint.

FIG. 6 is an enlarged partial cross-sectional view showing a chevron-shaped projection in another conventional pressure-resistant flexible pipe joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressure-resistant flexible pipe joint 2 Flexible cylinder 3 Flange connection part 4 Angle projection 5 Companion flange 6 Inner layer 7 Outer layer 8 Reinforcement cord 9 Metal ring 10 Pressure-resistant flexible pipe joint 11 Flexible cylinder 12 Angle Projection 13 Inner layer 14 Outer layer 15 Reinforcement cord 16 Metal ring

Claims (1)

[Claims] 1. A flexible tubular body 2 having flange connection portions 3 provided at both ends and a plurality of ring-shaped projections 4 formed at predetermined intervals on an intermediate outer peripheral portion. Is the inner layer 6
And an outer layer 7, between which and within the chevron 4, the reinforcing cord 8 is buried only in the vicinity of the outer periphery thereof, and an inner layer inside each chevron 4 and separated from the reinforcing cord 8 6. A pressure-resistant flexible pipe joint characterized in that a metal ring 9 is embedded in 6.