JP7135664B2 - Fluid pipe connection structure and fluid pipe connection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fluid tube connection structure and a fluid tube connection method.

For water pipes, ductile cast iron pipes such as those described in Patent Document 1, for example, are generally used. Ductile cast iron pipes are advantageous in that they are excellent in strength and ductility and joints can be integrally formed by casting. On the other hand, when using steel pipes for water pipes, welding has been conventionally used, but it has been proposed to simplify construction by using a joint member as described in Patent Document 2, for example.

JP-A-8-269614 JP-A-6-117591

However, when connecting steel pipes using a joint member, the number of parts increases and the structure becomes more complicated than when the pipe body and the joint are integrally formed by welding or ductile cast iron pipes. Further, when welding is not used, an adhesive or the like is used to connect the joint member to the steel pipe, but the long-term durability of the adhesive is not as high as that of the steel pipe or the joint member.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a novel and improved fluid pipe connecting structure and method for connecting steel pipes, which can connect steel pipes with a simple structure and achieve high durability. .

According to one aspect of the present invention, a first fluid pipe having an enlarged diameter portion formed at an axial end thereof and a first fluid pipe having a reduced diameter portion inserted into the enlarged diameter portion formed at an axial end thereof. 2, and a locking means that penetrates the enlarged diameter portion from the outside and does not penetrate the reduced diameter portion halfway, the inner peripheral surface of the enlarged diameter portion being in contact with the outer peripheral surface of the reduced diameter portion. A tight-fitting fluid conduit connection structure is provided.

According to another aspect of the present invention, the reduced diameter portion formed at the axial end of the second fluid pipe is inserted into the enlarged diameter portion formed at the axial end of the first fluid pipe. a step of closely contacting an inner peripheral surface of the enlarged diameter portion with an outer peripheral surface of the reduced diameter portion; and penetrating.

According to the present invention, since a separate joint member is not required, the structure is simple, and the tight contact between the inner peripheral surface of the enlarged diameter portion and the outer peripheral surface of the reduced diameter portion realizes high water resistance and durability. It is possible to obtain a fluid pipe connection structure and a fluid pipe connection method.

FIG. 4 is a diagram showing a part of steps of a method for connecting fluid pipes according to an embodiment of the present invention; 1 is a cross-sectional view showing a connection structure for fluid tubes according to an embodiment of the present invention; FIG. FIG. 4 is a diagram for explaining main external forces acting on a fluid pipe in soil; FIG. 4 is a diagram for explaining classification of bending of a fluid pipe; FIG. 4 is a diagram for explaining classification of bending of a fluid pipe; FIG. 4 is a diagram for explaining classification of bending of a fluid pipe;

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description.

FIG. 1 is a diagram showing part of the steps of a method for connecting fluid pipes according to an embodiment of the present invention. As shown in FIG. 1A, a fluid tube 1 (first fluid tube) and a fluid tube 2 (second fluid tube) are connected. Fluid pipe 1 and fluid pipe 2 are both steel pipes having an inner diameter d and an outer diameter D at their intermediate portions and capable of circulating various fluids such as liquid and gas. The fluid tube 1 is formed into a reverse tapered shape by press working or the like so that the inner diameter expands from d to d1 at _an enlarged diameter portion 11 having _a length L1 formed at the axial end. On the other hand, the fluid tube ₂ is formed into _a tapered shape by press working or the like so that the outer diameter is reduced from D to D1 at the reduced diameter portion 21 of length L2 formed at the end in the axial direction. A non-penetrating screw 3, which will be described later, is inserted through the expanded diameter portion 11 of the fluid pipe 1, and the through hole serves as a guide for positioning the non-penetrating screw 3 with respect to the fluid pipe 1 and for penetrating the contracted pipe portion 21. 31 may be preformed.

As shown in FIG. 1B, the reduced diameter portion 21 of the fluid tube 2 is inserted into the enlarged diameter portion 11 of the fluid tube 1 . At this time, the water stop material 4 may be applied to either or both of the inner peripheral surface 12 of the enlarged diameter portion 11 and the outer peripheral surface 22 of the reduced diameter portion 21 . The water stop material 4 is, for example, an elastomer having water-swelling properties, and is made by blending a macromolecular substance such as starch, cellulose, polyacrylate, or polyvinyl alcohol into natural rubber or chloroprene rubber. be. By applying the water-stopping material 4 in this step, a thin layer of the water-stopping material 4 is interposed between the inner peripheral surface 12 of the enlarged diameter portion 11 and the outer peripheral surface 22 of the reduced diameter portion 21 after the completion of the connection structure. As a result, the water cutoff between the fluid pipe 1 and the fluid pipe 2 can be further improved.

As shown in FIG. 1(C), by moving either or both of the fluid tube 1 and the fluid tube 2 in the axial compression direction, the outer peripheral surface 22 of the reduced diameter portion 21 is moved to the inner peripheral surface of the enlarged diameter portion 11 . It is brought into close contact with the surface 12 . Here, after the inner peripheral surface 12 of the enlarged diameter portion 11 and the outer peripheral surface 22 of the reduced diameter portion 21 are brought into close contact with each other, if an axial compressive force is further applied to the fluid pipes 1 and 2, the adhesion is further improved. do. In order to enable close contact as described above, the vertical cross-sectional gradient (d ₁ - d) / L ₁ of the inner peripheral surface 12 at the enlarged diameter portion 11 and the vertical cross-sectional gradient (D −D ₁ )/L ₂ are designed to be approximately equal. In the illustrated example, the outer diameter D1 of the fluid pipe 2 after diameter reduction is equal to the inner diameter d of the fluid pipe ₁ , and the inner diameter d1 of the fluid pipe ₁ after diameter expansion is equal to the outer diameter D of the fluid pipe 2. but not necessarily, if D ₁ <d or d ₁ >D and one of the enlarged diameter portion 11 or the reduced diameter portion 21 extends beyond the other, and D ₁ >d Alternatively, a case where d ₁ <D and there is a non-overlapping portion between the enlarged diameter portion 11 and the reduced diameter portion 21 is also allowed.

After the outer peripheral surface 22 of the diameter-reduced portion 21 of the fluid tube 2 is brought into close contact with the inner peripheral surface 12 of the enlarged-diameter portion 11 of the fluid tube 1 by the steps shown in FIGS. As shown in the cross-sectional view of FIG. 2, the fluid tube 1 and the fluid tube 2 are fixed by penetrating the non-through screw 3 from the outside of the enlarged diameter portion 11 to the reduced diameter portion 21 . The non-penetrating screw 3 penetrates the enlarged diameter portion 11 from the outside, while penetrating partway through the reduced diameter portion 21 but not penetrating it. ) does not enter into the inside of the fluid tube 21 so as not to affect the airtightness of the fluid tube 21 . The non-through screw 3 is, for example, a thread rolling screw for metal. In this case, the non-through screw 3 can be penetrated even if there is no screw hole on the reduced diameter portion 21 side. Although it is possible not to form the through-hole 31 on the enlarged diameter portion 11 side, the through-hole 31 is formed on the reduced diameter portion 21 side because it also serves as a guide for inserting the non-through screw 3 into the reduced diameter portion 21 side as described above. It will make your work easier. In this case, the through hole 31 may not be threaded. Further, a non-through hole, which is not threaded, may be formed on the reduced diameter portion 21 side in order to insert the non-through screw 3 . However, since the positional relationship between the diameter-enlarged portion 11 and the diameter-reduced portion 21 is not determined until the step of inserting the diameter-reduced portion 21 into the diameter-reduced portion 11 is completed, the non-through hole on the diameter-reduced portion 21 side is It is desirable to form it after the step of bringing the inner peripheral surface 12 of the portion 11 into close contact with the outer peripheral surface 22 of the reduced diameter portion 21 .

It is also possible to use a screw other than a thread rolling screw as the non-penetrating screw 3 . In this case, the through hole 31 on the enlarged diameter portion 11 side is threaded, and a threaded non-through hole for inserting the non-through screw 3 is also formed on the reduced diameter portion 21 side. As in the example of the thread rolling screw, it is desirable that the non-through hole on the side of the reduced diameter portion 21 is formed after the process of bringing the inner peripheral surface 12 of the enlarged diameter portion 11 into close contact with the outer peripheral surface 22 of the reduced diameter portion 21. be. In this embodiment, the non-penetrating screw 3 is used as a non-penetrating locking means that penetrates the enlarged diameter portion 11 from the outside and partially penetrates the diameter reducing portion 21. It is also possible to use means.

In the fluid tube connection structure according to the present embodiment, which is configured by the steps described above, the diameter-enlarged portion 11 and the diameter-reduced portion 21 formed in the fluid tubes 1 and 2 function as joints, respectively. The structure is simple because no joint member is required. Further, since the enlarged diameter portion 11 and the reduced diameter portion 21 are brought into close contact by being inserted in the axial compression direction, welding is not required. As described above, if the longitudinal cross-sectional gradients of the enlarged diameter portion 11 and the reduced diameter portion 21 are appropriately designed, the tight contact between the inner peripheral surface 12 of the enlarged diameter portion 11 and the outer peripheral surface 22 of the reduced diameter portion 21 causes High water stoppage can be obtained. Water stoppage can be further improved by applying the water stoppage material 4, but as described above, water stoppage is not achieved by relying only on the water stoppage material 4, so even if the water stoppage material 4 is It maintains its water-tightness even after aging and achieves high durability. The fluid pipe 1 and the fluid pipe 2 are fixed with the reduced diameter portion 21 in close contact with the enlarged diameter portion 11 using the non-penetrating screw 3 , but the non-penetrating screw 3 penetrates to the inside of the reduced diameter portion 21 . fluid cannot leak through the threaded hole.

In the connecting structure of the fluid pipes as described above, since the plate thickness of the fluid pipes is substantially doubled at the portion where the diameter-enlarged portion 11 and the diameter-reduced portion 21 overlap, the fluid pipes 1 and 2 are and high stress resistance in the radial direction. The main external forces acting on fluid pipes in the soil are earth pressure and surcharge loads, as shown in FIG. In the axial direction of the fluid pipes 1 and 2, the stress resistance is enhanced by the frictional force acting between the inner peripheral surface 12 of the enlarged diameter portion 11 and the outer peripheral surface 22 of the reduced diameter portion 21 and the bearing force of the non-through screw 3. However, in the case of a fluid pipe, the stress acting in the axial direction is smaller than the stress acting in the circumferential direction. Even when ₃ is about 0.7 times (0.7D) the outer diameter D of the fluid pipes 1 and 2, it is possible to obtain practically sufficient axial stress resistance.

4A, 4B, and 4C (where lines AA, BB, and CC indicate cross-sectional correspondences among the figures) illustrate the axis of the fluid tube. A bend B _A occurring vertically to the , a bend B _B occurring horizontally to the fluid tube, and a plate bend B _C to the fluid tube are shown. When it is assumed that a large stress is generated in the axial direction of the fluid pipe due to bending B _A and B _B caused by unbalanced soil water pressure, seismic load, etc., the overlapping length L ₃ shown in FIG. The pipes 1 and 2 are stretched to about twice the outer diameter D (2D), and the lengths L ₁ and L ₂ (see FIG. 1A) of the enlarged diameter portion 11 and the reduced diameter portion 21 are determined accordingly. You may

In the above example, the connection method and connection structure between the first fluid pipe having the enlarged diameter portion and the second fluid pipe having the reduced diameter portion were described. of fluid lines can be connected. In this case, a fluid pipe having an enlarged diameter portion formed at one axial end and a reduced diameter portion formed at the other end, or an enlarged diameter portion or a reduced diameter portion formed at both axial ends. is used.

Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention belongs can conceive of various modifications or modifications within the scope of the technical idea described in the claims. It is understood that these also naturally belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1... Fluid pipe, 11... Expanded diameter part, 12... Inner peripheral surface, 2... Fluid pipe, 21... Reduced diameter part, 22... Outer peripheral surface, 3... Non-penetrating screw, 31... Screw hole, 4... Water stop material.

Claims (6)

a first steel pipe having an enlarged diameter portion with a reverse tapered shape formed at an axial end thereof;
a second steel pipe formed with a tapered diameter- reduced portion inserted into the enlarged diameter portion at its axial end;
locking means that penetrates the enlarged diameter portion from the outside and partially penetrates the reduced diameter portion and does not penetrate,
A connection structure for fluid pipes, wherein the inner peripheral surface of the enlarged diameter portion is in close contact with the outer peripheral surface of the reduced diameter portion. 2. The connecting structure of fluid pipes according to claim 1, wherein a water stop material is interposed between the inner peripheral surface of the enlarged diameter portion and the outer peripheral surface of the reduced diameter portion. 3. The fluid tube connection structure according to claim 1, wherein said non-penetrating locking means is a thread rolling screw. a step of inserting the tapered reduced diameter portion formed at the axial end of the second steel pipe into the reverse tapered enlarged diameter portion formed at the axial end of the first steel pipe; ,
a step of bringing the inner peripheral surface of the enlarged diameter portion into close contact with the outer peripheral surface of the reduced diameter portion;
and a step of penetrating the enlarged diameter portion from the outside and partially penetrating the reduced diameter portion to insert a non-penetrating locking means. 5. The method of connecting fluid pipes according to claim 4, further comprising the step of applying a waterproofing material to at least one of the inner peripheral surface of the enlarged diameter portion and the outer peripheral surface of the reduced diameter portion. forming a through hole for inserting the non-penetrating locking means in the enlarged diameter portion;
a step of forming a non-through hole for inserting the non-penetrating locking means in the reduced diameter portion after the step of bringing the inner peripheral surface of the enlarged diameter portion into close contact with the outer peripheral surface of the reduced diameter portion; 6. A method of connecting fluid tubes according to claim 4 or claim 5, comprising:

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