JPH10132155A - Steel coil reinforcing flexible tube and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a flexible tube at a low cost by layering fiber cords at a fixed forming angle to form a flexible tube formed body, reducing the pitch of a steel coil reinforcing wire gradually from the central part to both end parts by compression, and forming a bellows-shaped peak part on a cylindrical shell wall. SOLUTION: A steel coiled reinforcing wire 7 is disposed at the cross-section central part of a cylindrical shell wall consisting of inner and outer rubber layers 2, 3, and rubber coated fiber reinforcing layers 4, 5 are formed at the inside and the outside of the reinforcing wire 7. In a reinforcing wire 7, its pitch P is reduced gradually from the central part toward both end parts, its cylindrical shell wall between reinforcing wire 7 is formed in bellows-shaped peak part to serve as a flexible part, and a flange 10 is fixed to both the end parts. The rubber coated fiber reinforcing layers 4, 5 are formed by winding and layering fiber cords, for example, 2 plys each, 4 plys in total around the surface of the inner surface rubber layer 2, the surface of the reinforcing wire 7 and an intermediate rubber layer 6 so that fiber directions may cross alternately at a smaller forming angle than the balancing angle of the hose.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earthquake-resistant flexible pipe used as an underground pipe for a water pipe, particularly a water pipe for water supply and sewerage, and more particularly to an earthquake-resistant steel excellent in bending, expansion and contraction and eccentricity. The present invention relates to an improvement in a coil-reinforced flexible tube and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, seismic flexible pipes used for underground pipes for water and sewage systems are shown in FIGS.
The one shown in (a) is known. Of these, the one represented by FIG. 10A is a steel ring 7 ′ and a first and second reinforcing layer 4 arranged at a constant pitch inside a rubber layer composed of an inner layer 2 and an outer layer 3. 5 are provided, and a cylindrical body wall made of these forms a bellows-shaped bulge bulging outward, and both ends thereof are fixed to a flange 10 via an end ring 8. FIG. 11 (a) shows a case where the outer peripheral surface is formed flat without forming a bellows-shaped peak portion, and FIG. 12 (a) shows a case where the steel ring 7 'is formed not only at the valley portion of the trunk wall but also at the peak portion. And increased rigidity. The other type is shown in FIG. 13 (a), in which a steel coil spring 7 having a constant pitch is arranged inside the inner and outer rubber layers 2, 3 to form the same structure as in FIG. 10 (a). It has improved axial elongation, compression and bending strength in the direction perpendicular to the tube axis.

[0003]

However, these conventional flexible pipes having a constant deformation reaction force over the entire length of the flexible part are used to fill landfills, the boundary between the landfills and the ground, or the cutting of hilly residential land. When buried in the ground at the boundary between soil and embankment, or in suddenly changing ground, liquefied area, etc., it may receive uneven sedimentation of the ground, uneven settling of the ground, unevenness of the ground, vertical displacement, depression, etc. When bending or eccentricity occurs as shown in FIGS. 14 and 15 due to the occurrence, at the fixed end body wall where the maximum stress occurs due to the seismic force, the fiber reinforced layer in the body wall is generated by the maximum stress. There have been problems such as breakage of the fiber cord, cracking or tearing of the trunk wall, or breakage of the trunk wall.

That is, as shown in FIG.
The flexible pipe end B buried in the ground moves downward due to the collapse of the soft ground due to, and the flexible pipe bends (displacement angle θ), and the fixed end A in the stable ground is pulled. Side trunk wall a
And a crack in the tension side wall f of the fixed end B in the soft ground,
Or tearing or torso rupture.

Further, as shown in FIG. 15, even when the flexible pipe is eccentric (displacement amount δ), the bending ends are respectively applied to the tension-side body walls a and f ′ of the fixed ends A and B. As before, cracks or tears occurred, or the torso wall was destroyed.

On the other hand, as shown in FIG. 16, when a left end portion A of a beam having a fixed cross-sectional shape is fixed and a load W is applied to a free end portion B, (1) acts on each cross section of the beam. A bending stress σ is generated at each section of the beam due to the bending moment M, causing tensile and compressive strains (elongation and contraction) at the top and bottom of each section, respectively, causing the beam to bend. (2) The bending moment M Is maximum at the fixed end A cross section (dangerous cross section) and generates the maximum bending stress.
(3) the bending of the beam proceeds until the maximum bending stress, that is, the maximum tensile stress and the maximum compressive stress, particularly the maximum tensile stress on the tensile side, is balanced with the allowable tensile stress of the fixed end beam A; When the maximum tensile stress exceeds the allowable tensile stress of the fixed end beam A, the fixed end beam A is known to break.

This is because the deflection curve y of the cantilever shown in FIG. 17 is y = W / 6EI (x ³ -3l ² x + 2l ³ ) (where y is the deflection, W is the load, E is the longitudinal elastic modulus, I is the moment of inertia of area, x is the distance from the point of application of the load, l
Indicates a length. ). That is, the beam is bent the most by the action of the bending moment M due to the load W without extending over the entire length l of the span, mainly in the vicinity of the fixed end A, that is, in a region where the differential coefficient of the deflection curve is significantly changed, In other regions, it is observed that the film is hardly bent and has a gentle curve or a straight line and is bent.

From the above findings, a conventional earthquake-resistant flexible pipe is buried in the ground and receives a large seismic force W at the other end B, thereby bending (displacement angle θ) as shown in FIG. 14 or FIG. ,
Or, when eccentricity (displacement amount δ) occurs, it is presumed that damage or breakage occurs through the following process. Due to the bending moment due to the seismic force W, a tensile stress and a compressive stress are generated at the uppermost portion and the lowermost portion of each section of the flexible pipe, respectively, and the flexible pipe starts to bend by causing elongation and contraction, respectively. Then, a maximum tensile stress is generated in the tension side body wall portion a of the fixed end portion A where the maximum bending moment acts, and the fiber cord of the rubber-coated fiber reinforcement layer in the body wall portion a is caused by the largest tensile stress. It is stretched beyond the allowable elongation and breaks. As a result, cracks or tears occur in the body wall portion a, or the body wall itself is broken.

The same is true for the flexible pipe fixed end portion B on the soft ground side, and the same applies to the flexible pipe fixed end portion B. The crack or tear is generated at the tension side body wall portion f or f 'of the fixed end portion B. Or destruction.

As described above, as shown in FIGS.
The conventional flexible pipe shown in FIG. 13 (a) is bent or eccentric due to seismic force, resulting in FIGS. 10 (b) to 13 (b).
As shown in FIG. 6, cracks or tears were generated at the tension side trunk wall portions of the fixed ends A and B, or the trunk wall portion was broken, so that it became unusable in many cases. Therefore, it is difficult to realize a larger bending (a large displacement angle θ or a small radius of curvature ρ) or an eccentricity (a large displacement amount δ), which is assumed from a target large seismic force. Was.

Also, from the manufacturing point of view, the one shown in FIG. 13 (a) shows that when the cylindrical body wall between the coiled reinforcing wires made of steel is expanded in the outer peripheral direction to form a bellows-shaped body wall, Since compression must be performed in the axial direction by a compression device while appropriately controlling air pressure or water pressure between the body wall and the mandrel, there is a problem that many facilities, processes and time are required.

[0012]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and has an extremely short length, which can freely follow ground distortion caused by a large seismic force, that is, vertical displacement and lateral displacement of the ground. Flexible tube and steel coiled reinforcing wire capable of large bending (large displacement angle or small radius of curvature) and eccentricity (large displacement) between flexible sections. Accordingly, it is an object of the present invention to provide a method of manufacturing a flexible tube having stable performance with high accuracy and economically.

[0013]

According to the flexible pipe of the present invention, the fiber cords are laminated at a fixed forming angle smaller than the equilibrium angle of the hose to form a flexible pipe formed body, and the cylindrical body of the flexible pipe is formed. The pitch of the steel coiled reinforcing wire placed at the center of the cross section of the wall is gradually reduced from the center to both ends by compression, and the cylindrical body wall between the pitches of the steel coiled reinforcing wire is made circular in the outer circumferential direction. By having a structure in which a bellows-shaped peak portion bulged in an arc shape is formed, the sectional moment of inertia I and the section modulus Z are increased toward both ends of the flexible tube, and the deformation reaction force, that is, the bending rigidity EI and The resistance moment σZ can be increased. As a result, the flexible pipe bends in the direction perpendicular to the pipe axis due to vertical displacement or lateral displacement of the ground due to seismic force, or causes displacement (eccentricity) in the direction perpendicular to the pipe axis, causing maximum bending stress at both fixed ends. Even so, the steel coil-shaped reinforcing wire rod whose pitch is gradually reduced to both ends and the elastic bellows-like body wall integrated with it are freely deformed and bent in the direction perpendicular to the pipe axis following this stress, Alternatively, displacement (eccentricity) in the direction perpendicular to the tube axis can be freely performed.

As described above, even if a large seismic force is applied, the steel coil-shaped reinforcing wire having a gradually reduced pitch from the center to both ends and the bellows-shaped body wall integrated with the steel coil-shaped reinforcing wire have large bending and eccentricity. It is a feature of the present invention that it works.

Further, according to the manufacturing method of the present invention, when the cylindrical body wall between the steel coiled reinforcing wires is expanded in the outer peripheral direction to form a bellows-like crest portion, the inner surface of the cylindrical body wall is pressurized. If compressed in the axial direction, the pitch of the coiled reinforcing wire is gradually reduced from the center to the end, and the cylindrical body wall between the coiled reinforcing wires is expanded outward integrally with this to form a bellows-like mountain can do.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a partially cutaway side view showing a configuration of a flexible tube 1 of the present invention. That is, this flexible tube 1
The steel coiled reinforcing wire 7 is disposed at the center of the cross section of the cylindrical body wall composed of the inner and outer rubber layers 2 and 3, and the rubber-coated fiber reinforcing layers 4 and 5 are provided inside and outside the coiled reinforcing wire 7.
The pitch P of the coil-shaped reinforcing wire 7 is gradually reduced from the center to both ends, and the cylindrical body wall between the coil-shaped reinforcing wires 7 is formed in a bellows-shaped mountain bulging outward. A flexible portion is formed, and both ends thereof are fixed to the flange 10.

The inner and outer rubber layers 2 and 3 are formed by forming a known rubber compound made of natural rubber or synthetic rubber according to a rubber tube into a sheet in advance and laminating the sheet.

The rubber-coated fiber reinforcing layers 4 and 5 are made of a fiber cord obtained by topping an unvulcanized rubber composition on a braided woven fabric made of fibers, the surface of the inner rubber layer 2, the coiled reinforcing wire 7 and the intermediate rubber layer. Forming angle 45 °, smaller than the equilibrium angle of the hose, with respect to the axis of the flexible tube on the surface of No. 6
Two plies are alternately wound so that the fiber directions intersect at 50 °, for a total of four plies, and are laminated and formed. The fibers used for the rubber-coated fiber reinforcing layers 4 and 5 include nylon,
Examples include organic fibers such as polyester, aramid, and carbon, and inorganic and metal fibers such as glass and steel. In addition, the equilibrium angle of the hose means that the fiber cord wound at a predetermined angle with respect to the pipe axis is used to compress the unvulcanized laminated molded pipe body formed in the axial direction, or When the peripheral surface is pressed in the outer peripheral direction, it is displaced in the radial direction and the axial direction and mechanically balanced to stand still, and is usually 54 ° 44 ′ with respect to the axis.

The intermediate rubber layer 6 is made of a known rubber compound. The intermediate rubber layer 6 integrates the coil-shaped reinforcing wire 7 and the inner and outer rubber-coated fiber reinforcing layers 4 and 5 and has a bellows shape bulging in the outer peripheral direction. Facilitates the expansion / contraction / bending action of the torso wall.

The steel coiled reinforcing wire 7 is a cylindrical coil spring in which a single wire is continuously spirally wound at a predetermined pitch, has a small spring constant, and has a flexible tubular cylindrical body wall. In accordance with the extension and shrinkage of the bellows-shaped ridge, it is easily displaced in the tube axis direction and the direction perpendicular to the tube axis. The coiled reinforcing wire 7 predicts the displacement angle and displacement of the flexible pipe from the ground strain at the time of the earthquake, and according to the buried pipe diameter,
A wire having a preferable transverse elastic modulus and other mechanical properties is appropriately selected, the wire diameter, the number of turns, and the like are determined, and the wire is designed and manufactured so as to obtain a predetermined spring constant. The wire forming the steel coiled reinforcing wire 7 is a metal wire material having a high elasticity limit, for example, a spring steel wire, a carbon steel wire for a spring such as a piano wire, and a spring alloy steel such as a stainless steel wire. A single wire such as a wire or a copper alloy wire for a spring such as a phosphor bronze wire can be used. This coiled reinforcing wire 7
Is axially fitted from the end on the outer peripheral surface of the inner rubber-coated fiber reinforcing layer 4 formed at the time of manufacture, and is disposed over the entire longitudinal direction. In addition, the coil-shaped reinforcing wire 7
Can be used alone as described above, or flanges 10 can be fixed to both ends thereof in advance by welding or the like via nipples 9 and used as an integral structural component.

As shown in FIG. 6, the end ring 8 is provided at the periphery of the opening on the fastening surface of the flange 10 and winds up the end 4a of the inner rubber-coated fiber reinforcing layer 4 and turns it back to form the flange 10. It has a role of firmly connecting the flexible portion to the flange 10 by sandwiching and fixing the flexible portion to the flange 10 by sandwiching and fixing the edge portion 2a of the inner surface rubber layer 2 to the fastening surface of the flange 10 as well. It is. The end ring 8 is desirably an annular steel member having a mechanical strength and a rectangular cross section.

The nipple 9 is fixed to the flange 10 in advance by welding or the like, and becomes a single part integrated with the flange when the joint is manufactured.

The nipple 9 is attached to the flange 10 in advance by welding or the like, and can be handled as a single part during manufacturing. And at the time of piping construction, it is connected to the buried pipe flange by bolting or the like. In addition, this flange 10
The ends of the nipple 9 are fixed to both ends of the coiled reinforcing wire 7 by welding or the like, so that the coiled reinforcing wire 7
And can be used as an integral part.

The mandrel 11 is a core mold of a flexible tube laminated molded body, and has a structure generally used, as well as a mandrel having a water or air circulation hole formed in a central body wall thereof. it can.

As shown in FIG. 2, a method of manufacturing the flexible joint 1 is as follows. First, a rubber sheet having a predetermined width is wound around the surface of the mandrel 11, and the butted portion is joined with an adhesive or the like to form a cylindrical shape. The inner rubber layer 2 is made. Further, a rubber tube may be used instead of the rubber sheet, and in this case, the joining operation can be omitted.

Next, as shown in FIG. 3, on the outer peripheral surface of the inner rubber layer 2, a band-shaped topping treated fiber cord 14 cut in advance to a predetermined width is balanced with the hose axis with respect to the axis of the pipe. Two plies are wound alternately and laminated so that the fiber directions 15 intersect at a forming angle φ smaller than the angle, and the inner rubber-coated fiber reinforcing layer 4 is formed. This forming angle φ is 45 °
It is set in the range of 50 °. When this forming angle is smaller than the equilibrium angle of the hose, as shown in FIGS. 19 to 20, when an external force is applied in the radial and axial directions of the wound cylindrical molded body, the fiber cord is displaced in the two directions. At 54 ° 44 'where the forces in both directions are balanced. As a result, as shown in FIG. 9, as the outer diameter increases, the thickness of the cylindrical body wall increases, and the bending rigidity (deformation reaction force) increases.

Subsequently, as shown in FIG. 4, an end ring 8 is fitted on the outer peripheral surface of the left end of the inner rubber-coated fiber reinforcing layer 4, and then a flange 10 with a nipple 9, a coiled reinforcing wire 7 and a nipple 9 The 'with flange 10' is fitted from the other end of the reinforcing layer 4 so as to slide on its surface, fitted and arranged over the entire longitudinal direction, and then the end ring 8 'is fitted.

As shown in FIG. 5, the end rings 8 at both ends,
8 ′ as a core, the edge 4 of the inner rubber-coated fiber reinforcing layer 4
a, 4a ', folded back and overlapped, and thereafter, the edges 2a, 2a' of the inner rubber layer 2 are also wound up.

Next, as shown in FIG.
0, 10 'and the coiled reinforcing wire 7 are stretched to both sides, and the flanges 10, 10' are brought into close contact with the end rings 8, 8 ', and both ends of the coiled reinforcing wire 7 are close to the flange nipples 9, 9'. Let it. In the case of using an integrally-structured component in which the flanges 10 are fixed to both ends of the coiled reinforcing wire 7, as shown in FIG. 4, it is only necessary to fit and arrange in the central portion on the inner rubber-coated fiber reinforcing layer. . Thereafter, as shown in FIG.
A rubber sheet 6 is wound around the surface of the wire so as to fill the pitch between the coiled reinforcing wires 7 to form an intermediate rubber layer 6.

Next, an outer rubber-coated fiber reinforcement layer 5 is formed on the surface of the intermediate rubber layer 6 by the same configuration and method as the inner rubber-coated fiber reinforcement layer 4. On the outer peripheral surface of the flange nipple 9. Further, a rubber sheet is wound around the surface of the outer rubber-coated fiber reinforcement layer 5 and joined to form the outer rubber layer 3.

The cylindrical molded body with a flange shown in FIG. 7 obtained as described above is compressed axially by a predetermined distance L from both ends thereof by pressing fittings 12 as shown in FIG. as shown in FIG. 9, with progressively reducing the pitch of the coiled reinforcement wire 7 from P ₀ of the central portion of the cylindrical molded bodies to P end, the cylindrical barrel wall between the coiled reinforcement wire in the outer circumferential direction Inflate to form bellows. At this time, the winding diameter D ₀ of the coil-shaped reinforcing wire 7 and the thickness t ₀ of the cylindrical body wall between the coil-shaped reinforcing wires gradually increase from the center to the end, and become t and D, respectively. When the cylindrical molded body is compressed in the axial direction, wax is applied to the surface of the mandrel 11 or a mandrel having a hole through which water flows through a part of the pipe is provided to facilitate compression of the cylindrical molded body. Preferably, means such as applying air pressure or water pressure between the molded body and its mandrel, or providing a rubber bag on these mandrels, sealing the compressed air after molding, and floating the molded body are preferable. Used. Usually, these pressures are applied in the range of 1 to ²⁰ kgf / cm ² .

Subsequently, after the outer peripheral surface of the bellows-shaped chevron wall is tightened by cloth wrapping and vulcanization is performed, the mandrel 11 and the press fitting 12 are removed to obtain the product shown in FIG.

Comparative Example 1 A natural rubber sheet was wound around a mandrel with a rubber bag having a diameter of 200 mm and joined to form an inner rubber layer (hardness 60 °, hardness 60 °).
A 1260 denier polyester blind cloth cord (yarn diameter 0.7 mm, 25 threads / 25 mm width) topped with natural rubber and formed on the outer peripheral surface at a molding angle of 54 ° 44 with respect to the axis of the product. 'And alternately laminate two plies on the inner rubber-coated fiber reinforcement layer (two layers, thickness 1 mm)
I got Next, an end ring (SS) is attached to the left end on this outer peripheral surface.
400, outer diameter 240mm, inner diameter 220mm, thickness 10m
m) and a flange (200AJ) with a nipple (STK, outer diameter 220 mm, thickness 5 mm) from the other right end.
IS 10K), then a polished bar steel ring (SS400,
Six (diameter: 8 mm, inner diameter: 220 mm) were placed in the central region at a pitch of 90 mm, and another one of the same end rings as described above was sequentially fitted to the right end. With the end rings at both ends as cores, first, the inner rubber-coated fiber reinforcing layer was wound and folded, and then the inner rubber was further wound thereon and folded up. Next, both ends of the polished steel bar ring were brought into close contact with the flange nipples at both ends. An intermediate rubber layer (natural rubber, width 31 mm, thickness 8 mm) is wound around and buried between the polish bar steel rings, and the outer rubber-coated fiber reinforcing layer (natural rubber) is further formed thereon in the same manner as the inner rubber-coated fiber reinforcing layer. Topping treatment 1260 denier polyester cord fabric cord, 2 plies, thickness 1 mm) was formed. Next, an outer rubber layer (natural rubber, hardness 60 °, thickness 4 mm) on it
Is wound, 4 kgf / cm ² of pressurized water is sealed in a rubber bag attached to the surface of the mandrel, and the inner wall of the obtained laminated molded tube is 540 m long while being pressed in the outer peripheral direction.
m are pressed inward by 60 mm each with a press fitting, and the pitch is 70 mm, the number of peaks is 6, and the length is 42.
An unvulcanized molded article of 0 mm was obtained. Then, with this unvulcanized molded product set to a total length of 420 mm, heat vulcanization (1
(45 ° C. × 60 minutes), and then cooled to remove the mandrel and the metal fitting to obtain a flexible tube sample having a length of 420 mm and an inner diameter of 200 mm.

Example 1 An inner rubber layer (natural rubber, hardness 60 °, thickness 8 mm) was formed on a mandrel with a rubber bag having a diameter of 200 mm, and a 1260 denier polyester blind cloth cord (topping treated with natural rubber) was formed thereon. A yarn diameter of 0.7 mm, 25 threads / 25 mm width) is alternately laminated in two plies at a molding angle of 50 ° with respect to the axis of the product, and the inner rubber-coated fiber reinforcement layer (2
Layer, thickness 1 mm). Next, an end ring (SS400, outer diameter 240 mm, inner diameter 220
mm, thickness 10 mm), and a nipple (STK, outer diameter 220 mm, thickness 5 mm) with a flange (200A JIS 10K) and a 90 mm pitch polished bar steel coil (SS400, wire diameter 8 mm, inner diameter) from the other right end An integral part with 220 mm and an effective number of turns of 6) was placed in the central region, followed by another end ring identical to the above at the right end. Next, using the end rings at both ends as cores, first, the inner rubber-coated fiber reinforcement layer was wound and folded, and then the inner rubber was further wound thereon and folded up. Next, the flanges at both ends of the polished bar steel coil were pressed against the end rings at both ends to bring them into close contact. Then, an intermediate rubber layer (natural rubber, width 31 mm, thickness 8 mm) is wound and filled between the pitches of the polishing steel bar coil, and an outer rubber-coated fiber reinforcing layer (natural rubber topping-treated 1260 denier polyester blind cloth cord, Ply, thickness 1m
m) was formed in the same manner as for the inner rubber-coated fiber reinforcing layer. Next, an outer rubber layer (natural rubber, hardness 60
°, 4 mm in thickness), and then 4 kgf / cm ² of water was sealed in a rubber bag attached to the surface of the mandrel. Both ends of the laminated molded tube were each compressed inwardly by 60 mm using a metal fitting to obtain an unvulcanized molded product having a pitch of 80 mm, 70 mm and 60 mm, a peak number of 6, and a length of 420 mm from the center to the end. Then, with this unvulcanized molded product set to a total length of 420 mm, it is heated and vulcanized (145 ° C. × 60 minutes), then cooled, and the mandrel and the press fitting are removed, and the length is 420 mm and the inner diameter is 2 mm.
A 00 mm flexible tube sample was obtained.

A displacement (eccentricity) characteristic test was performed on the flexible tube sample obtained in Example 1 of the present invention together with the conventional product of Comparative Example 1 which was determined to have the largest allowable eccentricity. As a result, the displacement amount δ of the flexible tube sample according to the first embodiment of the present invention.
Was 480 mm, whereas the conventional product sample of Comparative Example 1 was 260 mm. The displacement amount δ in the displacement characteristic test represents the displacement amount at the time of cutting the fiber cord of the rubber-coated fiber reinforcing layer at the fixed end cross section where the sample is eccentric and the maximum bending stress (maximum tensile stress) occurs under the load W.
The bending displacement angles at the time of cutting the fiber cord were 70 ° and 32 °, respectively.

As is clear from the above measurement results, the flexible tube obtained by the present invention is particularly different from the conventional flexible tube selected as a comparative example in terms of eccentricity (displacement amount), bending (displacement angle) and the like. Significant improvements in material mechanical properties were observed. That is, the flexible tube according to the structure of the present invention causes about twice the eccentricity and bending as compared with the conventional one, and the eccentric reaction force and bending reaction force required for the same amount of displacement are as small as 1/2. This is because the flexible pipe structure of the present invention gradually increases the bending stiffness (deformation reaction force) and the resistance moment from the center to both ends of the pipe, becomes maximum at both ends, and withstands the maximum bending stress due to seismic force. It is a testimony to the result of being able to do it. This suggests that it is possible to sufficiently follow the displacement of the ground in the direction perpendicular to the pipe axis during a larger earthquake than before. This is presumed to be largely due to the configuration of the steel coiled reinforcing wire having a gradually decreasing pitch toward the end of the flexible tube of the present invention and the bellows-shaped body wall having a gradually increasing thickness.

[0037]

As described above, according to the flexible pipe of the present invention, the steel coil pitch is minimized at both ends, and the height of the bellows-like mountain wall is maximized therebetween. Therefore, even if the flexible tube is bent or eccentric, the coil pitch and the body wall of this part are stretched to the maximum straightness, and can follow the elongation due to the maximum tensile stress. Damage can now be prevented.

Further, since the diameter of the body wall and the coil and the thickness of the body wall are gradually increased from the center to both ends, the bending stiffness (deformation reaction force) is also gradually increased and the radius of curvature is increased. Local and destructive deformation due to the formation of a very small radius of curvature at the end of the cut is prevented. Then, the entire flexible portion is subjected to slow deformation due to the formation of a radius of curvature that gradually increases toward the center portion, so that a very short flexible portion, for example, a flexible tube having six peaks, compared to the conventional product.
Bending and eccentricity as large as about twice can be performed.

Further, according to the production method of the present invention, the fiber cords are laminated at a constant molding angle smaller than the hose balancing angle to form a cylindrical molded body, which is simply compressed, and the central part is formed. The flexible pipe having a structure in which the steel coil pitch and the bellows-like body wall width between the pitches are gradually reduced from to the both ends can be economically manufactured without requiring much equipment and time. .

[Brief description of the drawings]

FIG. 1 is a partially broken side view showing a configuration of a flexible tube according to the present invention.

FIG. 2 is a partially broken side view showing a state in which an inner rubber layer is formed on a mandrel.

FIG. 3 is a partially broken side view showing a state in which an inner rubber-coated fiber reinforced sheet is wound around and laminated on an inner rubber layer.

FIG. 4 is a partially broken side view showing a state in which an end ring, a flange with a nipple, and a coiled reinforcing wire are arranged on an inner rubber-coated fiber reinforcing layer.

FIG. 5 is a partially broken side view showing a state in which the inner rubber-coated fiber layer and the inner rubber layer are wound up around an end ring and fixed.

FIG. 6 is a cross-sectional view of a main part showing a state in which the flange and the end ring are fixed by the inner rubber-coated fiber reinforcing layer and the inner rubber layer.

FIG. 7 is a cross-sectional view of a main part in which an intermediate rubber layer is formed between coiled reinforcing wires, an outer rubber-coated fiber reinforcing layer and an outer rubber layer are formed thereon, and fixed to a nipple.

FIG. 8A is a cross-sectional view of a main part of a trunk wall showing a state in which a laminated molded body molded with a normal mandrel is compressed to expand a trunk wall. (B) The body wall is inflated with a mandrel having a flow hole 1
It is a partial fracture | rupture principal part side view which shows an example.

FIG. 9 is an enlarged side view of a main part of a flexible pipe obtained by the manufacturing method of the present invention.

FIG. 10A is a partially cutaway side view showing a configuration of a conventional flexible pipe. (B) It is a side view which shows the state when the said flexible pipe is eccentric.

FIG. 11 (a) is a partially broken side view showing the configuration of another conventional flexible pipe. (B) It is a side view showing the state of eccentricity of the above-mentioned flexible tube.

FIG. 12 (a) is a partially cutaway side view showing the configuration of another conventional flexible pipe. (B) It is a side view showing the state of eccentricity of the above-mentioned flexible tube.

FIG. 13 (a) is a partially cutaway side view showing the configuration of another conventional flexible pipe. (B) It is a side view showing the state of eccentricity of the above-mentioned flexible tube.

FIG. 14 is a side view showing a state where a conventional flexible pipe bends due to ground strain caused by an earthquake.

FIG. 15 is a side view showing a state where a conventional flexible pipe is eccentric due to ground strain caused by an earthquake.

FIG. 16 is an explanatory diagram showing a state of bending (deflection) of a beam when a load acts on a free end of the cantilever.

FIG. 17 shows a deflection curve of the cantilever shown in FIG. 17;

FIG. 18 is a schematic diagram in which the radius of curvature of the center axis when the flexible tube of the present invention is eccentric is compared with a conventional product.

FIG. 19 is a schematic side view of a state in which the cylindrical molded body is compressed, the fiber cord group is displaced in the axial direction, and immediately before being displaced in the radial direction.

20 is a main part side view showing an angle of forming the fiber cord with respect to the axis when the displacement force of the fiber cord group of FIG. 19 is balanced and stationary, and a bellows-shaped crest having a width gradually reduced toward the end is formed. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flexible tube of this invention 2 Inner rubber layer 2a, 2a 'Edge of inner rubber layer 3 Outer rubber layer 4 Inner rubber-coated fiber reinforcement layer 4a, 4a' Edge of inner rubber-coated fiber reinforcement layer 5 Outer rubber Coated fiber reinforcing layer 6 Intermediate rubber layer 7 Steel coiled reinforcing wire 7 'Steel ring 8, 8' End ring 9, 9 'Nipple 10, 10' Flange 11 Mandrel 12 Press fitting 13 Flow hole 14 Fiber cord 15 Fiber Direction I Flexible tube of the present invention II Conventional flexible tube A, B Fixed end D₀, D Of the center and both ends of the coiled reinforcing wire
Diameter E Longitudinal modulus I Second moment of area L Compressed length M Bending moment P₀, P Pitch at center and both ends of coiled reinforcing wire W Seismic force Z Sectional coefficient a, b, c, d, e, f Tensile side wall crests a ′, b ′, c ′ of flexible pipe d ', e', f 'Compression of flexible tube
Side trunk wall mountain l Beam length  t₀, T Thickness of the center and both ends of the flexible tube body wall x Distance from load application point y Deflection α Static angle δ Displacement amount θ Displacement angle φ Forming angle ρ_a, Ρ_b, Ρ_c At both ends of the flexible tube center axis
Radius of curvature from center to center σ Bending stress

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FIF16L 23/024 23/028

Claims (4)

[Claims] 1. A steel coil-reinforced flexible tube having a cylindrical body wall formed of an inner and outer rubber layer, a steel reinforcing wire, and a fiber reinforcing layer having a shape bulging in an outer circumferential direction between the reinforcing wires. A rubber in which a steel coiled reinforcing wire having a constant pitch is disposed at the center of the cross section of the trunk wall, and laminated on the inside and outside of the steel coiled reinforcing wire at a forming angle smaller than the hose balancing angle with respect to the pipe axis. An inner / outer rubber-coated fiber reinforcement layer comprising a topping fiber cord is provided, and a laminated molded product obtained by providing an intermediate rubber layer and an inner / outer rubber layer between the inner and outer rubber-coated fiber reinforcement layers and inside and outside is subjected to an axial direction. Wherein the pitch of the steel coiled reinforcing wire is gradually reduced from a central portion to both ends thereof. 2. The steel coil-reinforced flexible tube according to claim 1, wherein the flange is joined to the steel coiled reinforcing wire. 3. An inner rubber-coated fiber reinforcing layer in which an inner rubber layer is formed on a mandrel, and a rubber topping fiber cord is laminated on an outer peripheral surface of the inner rubber layer at a forming angle smaller than a hose balancing angle with respect to a pipe axis. A steel coiled reinforcing wire having a constant pitch is fitted and arranged in the pipe axis direction at the center of the outer peripheral surface of the inner rubber-coated fiber reinforcing layer, and flanges are provided at both ends of the steel coiled reinforcing wire. An end ring is provided, and an end portion of the inner rubber-coated fiber reinforcing layer and an inner rubber layer are integrally formed and fixed to the flange and the end ring, and a steel coil is formed on an outer peripheral surface of the inner rubber-coated fiber reinforcing layer. After forming an intermediate rubber layer, an outer rubber-coated fiber reinforcement layer, and an outer rubber layer that fill the pitch between the reinforcing wire rods to form a cylindrical laminated molded body, the molded body is compressed in the axial direction of the tube from both ends by metal fittings. And the steel core The pitch of the ill-shaped reinforcing wire is gradually reduced from the center to both ends, and the cylindrical body wall between the steel coil-shaped reinforcing wires is expanded in the outer circumferential direction and further vulcanized. Manufacturing method of tube. 4. The method according to claim 3, wherein the flange is joined to the steel coiled reinforcing wire.