JPH11280972A - Expansion joint for underground installation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the strength of an outer surface layer so as to enhance durability by providing an outer surface protective cover in the outer periphery of an inner pipe part at an air gap, and providing a sponge layer in the air gap to prevent an expansion joint from coming into contact with the outer surface protective cover surface of the inner pipe part and absorb a displacement. SOLUTION: A flexible inner pipe 2 has mouthpieces 3, 4 integrally fitted to both ends thereof, an outer surface protective cover 5 is provided to cover the inner pipe 2, and a sponge layer 6 is filled between the inner pipe 2 and the outer surface protective cover 5. The sponge layer 6 is a member for absorbing a displacement, which is formed of foamed rubber, or celluar plastic to be flexible and have elasticity. Accordingly, the displacement can be absorbed well in a simple structure, and as the flexible part is not exposed to the outside, the joint is kept from coming into contact with an object in the outside to be damaged so as to improve durability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion joint for underground burial, and more particularly to an expansion joint for underground burial which prevents a flexible tube made of rubber from being damaged, thereby preventing an accident from occurring. Related to expansion joints.

[0002]

2. Description of the Related Art An expansion joint (flexible joint) has the performance of an expansion joint, and is also called a flexible expansion tube (simply a flexible tube), and is buried in the soil from structures such as a pump station and a water bridge. It is used in places where pipes are to be installed, and places on soft ground that cause uneven settlement. It is used to absorb sudden sinking at these locations that cannot be absorbed by conventional expansion joints, and is used to dampen the connection of equipment that generates unique vibrations such as pumps and blowers. The flexible pipe is usually formed in a bellows (bellows) shape and can be expanded and contracted and bent at a large angle in a structurally reasonable shape. Currently, there are two types of water pipes: stainless steel and rubber. Things are mainly used. In addition, in the classification according to the type of bending, there are often used classifications such as a universal type that bends freely vertically and horizontally and a hinge type that bends vertically. The sinkage absorption may be up to about 1 m, depending on the purpose of use and geological conditions. In order to absorb such a large settlement, there are a method of directly joining two flexible tubes, a method of using two flexible tubes with a short tube therebetween, and the like.

In a conventional expansion joint, a reinforcing cloth is wrapped around a flexible tube made of rubber to receive internal pressure, is supported by a reinforcing ring against external pressure, and a rubber layer against contact with the outside. , And the ends are provided with bases such as nipple flanges, tie bolts or hinge fittings to connect the expansion joints or adjacent structures or pipes.

[0004]

However, the above-mentioned conventional expansion joint has the following problems. That is, since the outer surface of the main portion of the flexible tube is made of rubber, the flexible tube directly hits an angular stone or a structure at the time of transportation or back-filling of the flexible tube, causing a tear. After laying the flexible tube, when excavating the vicinity of the flexible tube due to other plumbing work such as electricity and gas, it was sometimes damaged by a shovel, pickaxe or the like. Since the soil is closely attached to the periphery of the flexible tube in the soil, the deformation of the flexible tube is restricted by earth and sand, and an excessive stress is generated.

In view of such problems, the present inventor has conducted various studies and tests. As a result, the rubber surface of the expansion joint is covered with a strong cover and a flexible vibration absorbing member is provided between the rubber surface and the cover. It was clarified that by interposing a material, the rubber of the elastic body was protected, the restriction of deformation in the soil was reduced, the displacement was freer, and the durability was increased.

The present invention has been made on the basis of the above-described viewpoints. The object of the present invention is to increase the strength of the outer surface layer and to absorb the displacement in an intermediate gap to improve durability. An object of the present invention is to provide an expansion joint capable of increasing the performance.

[0007]

An expansion joint according to a first aspect of the present invention as a means for solving the above-mentioned problem is a flexible inner tube, and a flexible inner tube and both ends of the inner tube are integrally formed. An underground buried expansion joint comprising a base attached to an inner pipe portion, an outer surface protective cover provided with a gap around the inner pipe section, a sponge layer provided in the gap, and the inner pipe formed by the sponge layer. It is characterized by preventing contact with the outer protective cover surface of the portion and absorbing displacement.

According to a second aspect of the present invention, in the expansion joint, the inner pipe portion includes an inner rubber layer, a reinforcing cloth layer, a reinforcing wire, an intermediate rubber layer, an outer peripheral reinforcing cloth layer, and an outer rubber layer. The protective cover is made of a cylinder formed of a rigid metal, glass fiber reinforced plastic, carbon fiber reinforced plastic, ceramic fiber reinforced plastic, or the like. The expansion joint according to claim 3 is the expansion joint according to claim 1 or 2, wherein the sponge layer has a hardness Hs of 5 to 80 (SRIS).
-C) and a porosity of 45 to 95%. Here, the sponge layer can be usually formed of sponge rubber (vulcanized rubber having a spongy porous structure). However, the sponge is not limited to the sponge rubber, and the sponge forming the sponge layer includes a porous nonwoven fabric (cotton).

In the present invention, the SRIS-C hardness (hardness) refers to SRIS-0101 4.2 (1 kg load using an ASKER C type tester manufactured by Kobunshi Keiki Co., Ltd.).
And a method of observing the scale after 30 seconds). The metal used for the outer protective cover is
Examples include steel and stainless steel. The plastic to be reinforced with fibers or the like is not particularly limited, but conventionally known resins such as epoxy resin, polyester resin, polyamide, and polyethylene can be used. Also, as a reinforcing material,
Not only glass, carbon and ceramic but also aramid and the like can be used. As the form of the fiber, roving, yarn, chopped strand, mat, woven material, or the like can be used.

[0010] If the hardness Hs of the sponge layer is less than 5, the sponge layer is too soft and the compression set becomes large, and there is a possibility that the sponge layer becomes unusable. If Hs exceeds 80, the displacement of the inner rubber layer 2 is reduced. This limits vibration and makes it impossible to absorb vibration, and also reduces durability.

According to the expansion joint of the present invention, the flexible inner pipe is interposed between the pipes or between the pipe and the structure, and is displaced as the structures at both ends are displaced, so that the flexible inner pipe is deformed, thereby absorbing the displacement. I do. Even if it is buried in the soil and external pressure is applied from the surroundings, the outer surface protection cover takes over and the external pressure is not applied to the flexible inner tube portion. Even if there is an angular stone or the like in the periphery, it does not come into contact with the flexible inner tube portion, so that it is not damaged. In addition, since the sponge layer is provided between the inner tube and the outer surface protective cover, the inner tube and the outer surface protective cover do not come into direct contact with each other. Nothing.

[0012]

As is apparent from the above description, according to the expansion joint of the first aspect, an outer surface protective cover is provided with a gap around the inner pipe portion, and a sponge layer is provided in the gap. The layer prevents the contact with the outer protective cover surface of the inner tube portion and absorbs the displacement, so that the displacement can be well absorbed with a simple structure, and the flexible portion is not exposed to the outside, so that it is not exposed to external objects. Durability can be improved because there is no damage due to contact.

According to the expansion joint of the present invention, the inner pipe portion is composed of an inner rubber layer, a reinforcing cloth layer, a reinforcing wire, an intermediate rubber layer, an outer peripheral reinforcing cloth layer, and an outer rubber layer, and the outer surface protection. The cover is made of a rigid metal, glass fiber reinforced plastic, carbon fiber reinforced plastic, or ceramic fiber reinforced plastic, so the inner tube can withstand internal pressure, and the outer surface can withstand external pressure. Since the protective cover is responsible, it is possible to arbitrarily increase the pressure resistance against external pressure. According to the expansion joint of claim 3, the sponge layer has a hardness Hs of 5 to 80 (SRIS-C) and a porosity of 45.
Since it is set to 95%, the inner tube portion can be freely displaced, and the durability is improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the present invention. FIG. 1 is a front view of an expansion joint, and FIG. 2 is a piping diagram showing an example in which an expansion joint is provided in a pipe.

The expansion joint 1 of the present embodiment is, roughly speaking, a flexible inner tube portion 2, and bases 3 and 4 are integrally attached to both ends of the inner tube portion 2 so as to cover the inner tube portion 2. An outer protective cover 5 is provided, and a sponge layer 6 is filled between the inner pipe 2 and the outer protective cover 5.

In the inner tube portion 2, a reinforcing cloth layer 12, an intermediate rubber layer 13, a reinforcing cloth outer layer 14, and an outer rubber layer 15 are sequentially arranged from the innermost inner rubber layer 11 to the outer side. It is formed embedded in the layer 13. And
The bases 3 and 4 are integrally attached to both ends of the inner tube portion 2.

The inner rubber layer 11 of the inner tube portion 2 is made of natural rubber,
Alternatively, synthetic rubbers such as chloroprene rubber (CR), styrene butadiene rubber, butadiene rubber, butyl rubber (IIR), and ethylene propylene rubber (EPM, EPDM) are used, and are hardly exposed to the outside. Natural rubber or a mixture of natural rubber and synthetic rubber is suitable because it does not need to be considered. The inner rubber layer 11 is prepared by mixing a rubber raw material with a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a reinforcing agent such as carbon black, a filler, a softening agent, an antioxidant, etc. It is obtained by doing. Satisfies the standard of rubber tube suitable for the application, and the rubber hardness at the time of vulcanization is 50-65 Hs (JISA).
It is preferable to use the following.

The reinforcing cloth layer 12 and the reinforcing cloth outer layer 14 are layers that cover the internal pressure of the flexible portion of the expansion joint 1 and protect the rubber layers 11 and 15 from the reinforcing wires 16 respectively. Tire cords used for automobile tires, etc. are processed with an adhesive resin and rubbed with rubber glue (gum-dipped). ) It is formed by bonding. The reinforcing cloth layer 12 is formed from the reinforcing wire 16 to the inner rubber layer 11.
And the outer reinforcing cloth layer 14 protects the outer rubber layer 15 from the reinforcing wires 16.

The intermediate rubber layer 13 is a layer formed by embedding the reinforcing wire 16 and preferably has good adhesion to the reinforcing wire 16, the reinforcing cloth layer 12, and the outer layer 14 of the reinforcing cloth and is excellent in breaking. As the rubber composition of the intermediate rubber layer 13,
The above various rubbers can be used, and in order to prevent the rubber from being broken at the time of bending, the rubber hardness at the time of vulcanization is softer than the inner rubber layer, and Hs (JIS A) of 40 to 50 is used. Is preferred. And the intermediate rubber layer 13
In the same manner as the formation of the inner rubber layer 11, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a reinforcing agent such as carbon black, a filler, a softener, an antioxidant, etc. It is formed by vulcanization and molding.

The outer rubber layer 15 is a layer partially exposed in the soil, and is the same as the inner rubber layer 11, such as natural rubber, chloroprene rubber (CR), styrene butadiene rubber, butadiene rubber, butyl rubber (IIR), ethylene propylene. Synthetic rubber such as rubber (EPM, EPDM) can be used. Since the outer rubber layer 15 may be exposed to the outside,
CR, EPM, EPDM, etc. which are resistant to aging are suitable. Then, the outer rubber layer 15 is formed similarly to the inner rubber layer 11. The standard satisfies the standard of the rubber tube suitable for the application, and the rubber hardness at the time of vulcanization is Hs (JIS
It is preferable to use one having A) of 50 to 65.

The reinforcing wire 16 is a member that bears a load applied to the reinforcing cloth layers 12 and 14, and a load W = P × D × H (here, P: internal pressure (kg / kg)
cm ² ), D: inner diameter (cm), H: pressure receiving width (cm), and assuming that this load W is applied to the wire, the wire can withstand a cutting load at two places on the circumference and has an allowable stress of 800 to 1
At 000 kg / cm ² , the thickness of the wire and the number of turns are determined.
As the wire, a galvanized iron wire having a diameter of 5 mm is usually used.

The bases 3 and 4 are formed by flanges, and are integrally formed at both ends of the inner tube portion 2. The ferrules 3 and 4 are used to connect the expansion joint 1 to a structure, a pipe, or the expansion joint. Base 3,
Rubber packings 3a, 4a having the same composition as the inner rubber layer 11 are formed on the outer surface of each of the four. When the rubber packings 3a and 4a are connected to the adjacent members, it is not necessary to separately interpose a packing, so that the connecting operation becomes easy and the cost of the packing can be reduced.

The outer surface protection cover 5 prevents the inner tube portion 2 from being crushed when subjected to earth pressure, a load when passing through a vehicle, etc., and directly hits a square stone or a structure, or is used for other piping work. It is a member that covers and prevents damage by a shovel, pickaxe, etc. when digging around the flexible tube. External protective cover 5
As a material of the metal, a metal such as steel or stainless steel, a reinforced plastic such as a glass fiber reinforced plastic, a carbon fiber reinforced plastic, or a ceramic fiber reinforced plastic is used. The cross-sectional area of the outer surface protection cover 5 varies depending on the external pressure and the diameter. The gap between the inner pipe 2 and the outer surface protection cover 5 can be set within a large range by design displacement. The gap between the inner pipe portion 2 and the outer surface protective cover 5 acts as a free space that can be displaced without being affected by the buried earth and sand as a displacement absorbing space of the expansion joint 1 and is displaced without applying unreasonable stress. And durability can be improved. Furthermore, the inner tube part 2
By providing the sponge layer 6 in the gap between the outer cover 5 and the outer surface, the surface of the flexible inner tube 2 is protected.

The sponge layer 6 is a member for absorbing displacement,
It is formed to be flexible and elastic from foamed rubber or foamed plastic such as foamed polyurethane, foamed polystyrene and foamed polyethylene. The hardness Hs of the sponge layer 6 is 5 to 80, more preferably 15 to 70 in SRIS-C hardness. If the hardness Hs is less than 5, it may be too soft and the compression set may be large, resulting in a state where it cannot be used. If the hardness Hs exceeds 80, the displacement of the inner rubber layer 2 is limited, and the durability is increased. Gets worse.
The specific gravity of the sponge layer 6 is not particularly limited, but is generally about 0.5 to 0.055 g / cm ³ and the porosity is about 40 to 95%.

The rubber material of the foamed rubber is not particularly limited, and a material conventionally used as a rubber elastic body is used. The types include ethylene-propylene-diene rubber (EPDM), polynobornene rubber, styrene-butadiene rubber (SBR), chloroprene rubber (CR), silicone rubber, epichlorohydrin rubber, chlorinated ethylene-propylene-diene rubber (CI-EPDM). ), Natural rubber, isoprene rubber, butyl rubber and the like are preferably used. In particular, EPDM,
CI-EPDM and epichlorohydrin rubber are particularly preferably used.

Further, as a material of the polyurethane foam,
Conventionally known urethane foam substrates such as polyhydroxyl compounds and polyisocyanate compounds are used. As a base material of a foamed plastic such as a foamed polystyrene or a foamed polyethylene, a conventionally known material can be used.

The molding of the expansion joint of the present invention is as follows.
A rubber compound, a vulcanizing agent, a vulcanization accelerator, a vulcanization aid, a reinforcing agent such as carbon black, a filler, a softening agent, an antioxidant, etc., which form the compound No. 1 are compounded and molded. Then
A rubber cloth is rubbed with an adhesive resin process (gum dipping) on a tire cord on a tire cord, and the molded product is laminated on a rubber sheet at an angle to form a reinforcing cloth layer 12.
Next, the reinforcing wire 16 is wound around the formed body formed up to the reinforcing cloth layer 12, and then placed in a mold to form the intermediate rubber layer 13.
Forming a rubber raw material, vulcanizing agent, vulcanization accelerator, vulcanization aid,
A mixture containing a reinforcing agent such as carbon black, a filler, a softener, an antioxidant, and the like is injected and molded. Next, the molded article having the intermediate rubber layer 13 formed thereon is subjected to resin bonding (gum dipping) to a tire cord, rubbed with rubber glue, and rubbed with a rubber sheet. I do. Subsequently, the outer rubber layer 15 is formed in a mold, and the ferrules 3 and 4 and the inner tube 2 form an integrated body, followed by vulcanization molding.

Finally, the outer surface protective cover 5 and the vulcanized molded body of the inner tube portion 2 are arranged in a mold, and a foamed rubber material is injected into these gaps and foamed to produce an expansion joint.

The expansion joint constructed as described above can be used similarly to a conventional flexible tube. That is, when the displacement is large, two expansion joints are provided. As shown in FIG. 2, when a short pipe is installed horizontally with the expansion joint separated by L in the horizontal distance, and as shown in FIG.
L is obtained as follows. ΔL = XL, where X is the distance between the expansion joints after displacement = Y / sin θ, L = Y / tan θ, and Y is the amount of displacement in the vertical direction. Since the elongation ΔL is absorbed by the two expansion joints, one is ΔL / 2.

The present invention is not limited to the above-described embodiment, but can be variously modified. By the way, in the above-described embodiment, after being formed into an expansion joint shape, vulcanization molding and foaming are performed.
After sequentially performing vulcanization molding, a sponge layer may be formed. In addition, although an example is shown in which the base is formed by a flange, one may be formed as a flange, the other as a bevel end, or both as a bevel end.

[Brief description of the drawings]

FIG. 1 is a front view of an expansion joint according to an embodiment of the present invention.

FIG. 2 is a piping diagram showing an arrangement example of an expansion joint.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Expansion joint, 2 ... Inner tube part, 3 ... Base, 4 ... Base, 5 ... Outer surface protection cover, 6 ... Sponge layer, 7 ... Buried piping, 11・
..Inner rubber layer, 12: reinforcing cloth layer, 13: intermediate rubber layer, 14: reinforcing cloth outer layer, 15: outer rubber layer,
16 ... Reinforcing wire

Claims (3)

[Claims] 1. An underground expansion joint comprising a flexible inner tube portion and bases integrally attached to both ends of the inner tube portion, wherein a gap is formed in the outer periphery of the inner tube portion. An outer surface protective cover, a sponge layer provided in the gap, the sponge layer preventing contact with the outer surface protective cover surface of the inner tube portion, and absorbing displacement. . 2. The inner pipe part comprises an inner rubber layer, a reinforcing cloth layer, a reinforcing wire, an intermediate rubber layer, an outer peripheral reinforcing cloth layer, and an outer rubber layer, and the outer protective cover is a rigid metal cylinder; The expansion joint for underground burial according to claim 1, comprising a cylindrical body formed of glass fiber reinforced plastic, carbon fiber reinforced plastic, ceramic fiber reinforced plastic, or the like. 3. The sponge layer has a hardness Hs of 5 to 80.
(SRIS-C) and a porosity of 45 to 95%.
Or an expansion joint for underground burial according to 2 above.