JP2006046019A - Joint structure of steel pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable joint structure of a steel pipe having a simple structure and capable of facilitating construction and reducing manufacturing cost. <P>SOLUTION: An outer side joint pipe 1 fixed to the steel pipe 31 is provided with a first inside diameter part 8, a second inside diameter part 4, and a locking part 5 for connecting both of the parts. An inner side joint pipe 11 fixed to a steel pipe 32 and joined with the outer side joint pipe 1 detachably is provided with a first outside diameter part 12, a second outside diameter part 14, a third outside diameter part 17, an abutting part 13 for connecting both of the first and second outside diameter parts, and an engaging projection 16 for connecting both of the second and third outside diameter parts. A cylindrical part 22 remains in a predetermined scope close to the steel pipe of the second outside diameter part 14, and a part close to a tip is divided into divided pieces 21 by a slit 15. When mounting the inner side joint pipe 11 on the outer side joint pipe 1 and detaching it from the outer side joint pipe 1, the divided pieces 21 are bent. When joining the inner side joint pipe 11 with the outer side joint pipe 1, the abutting part 13 of the inner side joint pipe 11 is abutted on an upper end part 2 of the outer side joint pipe 1, and the engaging projection 16 of the inner side joint pipe 11 is locked in a locking part 5 of the outer side joint pipe 1 or the cylindrical part 22 of the inner side joint pipe 11 is abutted on the first inside diameter part 8 of the outer side joint pipe 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a joint structure in the axial direction of a steel pipe, for example, a steel pipe pile or a precast concrete pile (PHC pile, PRC pile, SC pile).

  Steel pipe piles such as soil cement synthetic steel pipe piles are generally constructed by welding and joining at construction sites. However, with joints by welding, it is hoped that a joint structure to replace welding will be developed because (1) the quality of the welded part depends on the skill of the welding operator and (2) the construction depends on the weather. It was rare.

  As an example of a welded pipe structure that does not involve welding, a cylindrical connection part having an outer diameter smaller than the diameter of the steel pipe is coaxially fixed to the butt edge of each steel pipe to be connected, and the side surface of the cylindrical connection part is fixed. A large number of screw holes are provided on the steel pipes, the cylindrical connection parts fixed to the steel pipes are butted against each other, and the outer circumferences of the two cylindrical connection parts are appropriately divided into arc shapes, The cylindrical joints with a large number of bolt insertion holes are covered, and the bolt insertion holes of the divided cylindrical joints are aligned with the screw holes of the cylindrical connection parts, and the bolt ends are passed through the bolt insertion holes. The steel pipes are connected to each other by screwing them into the screw holes, and the divided cylindrical joints fixed to the cylindrical connecting part and the heads of the tightened bolts are connected to the outer diameter of the connecting steel pipes. I won't stick out There are those (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 7-19516 (page 4, FIG. 2)

Since the connection structure of the steel pipe described in Patent Document 1 uses a split cylindrical joint separate from the steel pipe pile and integrates it with a bolt, not only the upper joint and the lower joint are engaged, but also the split cylindrical joint Therefore, it is necessary to manufacture with high precision considering the meshing of the upper and lower joints. Moreover, the work of separately transporting and attaching the divided cylindrical joint is necessary, and the workability is poor.
In addition, when the diameter of the steel pipe joint is increased and the wall thickness is increased, the weight of the split cylindrical joint increases, and transportability and workability are further deteriorated. Become.
In addition, if a horizontal force that causes the upper joint and lower joint to be eccentric acts, the force acting on the bolt will fluctuate, loosening the bolt, and reducing the durability and reliability of the steel pipe connection structure. There are various problems.

  The present invention has been made to solve the above problems, and has an object to provide a steel pipe joint structure that is simple in structure, easy to construct, can reduce costs, and has high reliability. Is.

(1) A steel pipe joint structure according to the present invention includes an outer joint pipe fixed to one steel pipe, and an inner joint pipe fixed to the other steel pipe and detachably joined to the outer joint pipe. ,
The outer joint pipe has a first inner diameter portion located closer to the tip, a second inner diameter portion located closer to the steel pipe than an inner radius of the first inner diameter portion, and the first inner diameter portion and the second inner diameter. A locking part located between the two parts,
The inner joint pipe has an outer radius larger than an inner radius of the first inner diameter part of the outer joint pipe and is positioned closer to the other steel pipe, and an inner diameter of the first inner diameter part of the outer joint pipe A second outer diameter portion positioned substantially closer to the tip than the first outer diameter portion, substantially the same as the inner radius of the second inner diameter portion, and having the same outer radius as the radius, and the second outer diameter portion A third outer diameter portion located at an outer radius equal to or greater than the outer radius and closer to the tip than the second outer diameter portion; and a step portion located between the first outer diameter portion and the second outer diameter portion; An engagement protrusion positioned between the second outer diameter part and the third outer diameter part, and a cylindrical part in a predetermined range near the steel pipe of the second outer diameter part,
In the range closer to the tip than the cylindrical part of the second outer diameter part of the inner joint pipe and the third outer diameter part, it has a diameter reducing function at the time of attachment and detachment,
When the inner joint pipe is joined to the outer joint pipe, a step portion of the inner joint pipe comes into contact with a tip portion of the outer joint pipe, and an engagement protrusion of the inner joint pipe is engaged with a locking portion of the outer joint pipe. Are substantially in contact with each other, and the outer surface of the cylindrical portion of the inner joint pipe is substantially in contact with the inner surface of the first inner diameter part of the outer joint pipe.

(2) Further, in the steel pipe joint structure according to the present invention, the diameter reducing function includes a range of the second outer diameter portion of the inner joint pipe closer to the tip than the cylindrical portion, and the third outer diameter portion. Is divided into a plurality of divided pieces by slits provided in the axial direction,
When the inner joint pipe is attached to and detached from the outer joint pipe, the divided piece is bent.

  (3) Furthermore, the joint structure of the steel pipe according to the present invention includes a second inner diameter part of the outer joint pipe and a third outer diameter part of the inner joint pipe when the inner joint pipe is joined to the outer joint pipe. The outer surface of the third outer diameter part of the inner joint pipe is pressed against the inner surface of the second inner diameter part of the outer joint pipe by fastening the bolt with a bolt.

(4) Moreover, the steel pipe joint structure according to the present invention is provided with a bolt insertion hole in the second inner diameter portion of the outer joint pipe,
Corresponding to the bolt insertion hole, a bolt screw hole is provided in the third outer diameter portion of the inner joint pipe,
When the inner joint pipe is joined to the outer joint pipe, a fastening bolt inserted through the bolt insertion hole is screwed into the bolt screwing hole, whereby an inner surface of the second inner diameter portion of the outer joint pipe is joined to the inner side. The outer surface of the third outer diameter portion of the joint pipe is pressed.

(5) Furthermore, the steel pipe joint structure according to the present invention includes an outer joint pipe fixed to one steel pipe, and an inner joint pipe fixed to the other steel pipe and detachably joined to the outer joint pipe. Have
The outer joint pipe has a first inner diameter portion located closer to the tip, a second inner diameter portion located closer to the steel pipe than an inner radius of the first inner diameter portion, and the first inner diameter portion and the second inner diameter. A locking portion located between the second inner diameter portion and the projecting step portion located between the second inner diameter portion and the steel pipe, and a cylindrical portion in a predetermined range near the steel pipe of the second inner diameter portion,
The inner joint pipe has an outer radius substantially the same as an inner radius of the first inner diameter part of the outer joint pipe, a second outer diameter part positioned closer to the other steel pipe, and an inner radius of the second inner diameter part, A third outer diameter portion that is substantially the same and has an outer radius that is equal to or greater than the outer radius of the second outer diameter portion and that is positioned closer to the tip than the second outer diameter portion; and the second outer diameter portion and the third outer diameter An engagement protrusion positioned between the diameter portion,
In the range closer to the tip than the cylindrical part of the second inner diameter part of the outer joint pipe and the first inner diameter part, it has a function of expanding the diameter at the time of attachment and detachment.
When the inner joint pipe is joined to the outer joint pipe, the protruding step portion of the outer joint pipe comes into contact with the distal end portion of the inner joint pipe, and the inner joint pipe is engaged with the locking portion of the outer joint pipe. The protrusions are substantially in contact with each other, and the outer surface of the third outer diameter portion of the inner joint tube is substantially in contact with the inner surface of the cylindrical portion of the outer joint tube.

(6) Furthermore, in the joint structure of the steel pipe according to the present invention, the diameter expansion function is such that the range of the second inner diameter part of the outer joint pipe closer to the tip than the cylindrical part and the first inner diameter part are: It is divided into a plurality of divided pieces by slits provided in the axial direction,
When the inner joint pipe is attached to and detached from the outer joint pipe, the divided piece is bent.

  (7) Further, in the steel pipe joint structure according to the present invention, when the inner joint pipe is joined to the outer joint pipe, the outer joint pipe and the second outer diameter portion of the inner joint pipe are fastened with bolts. By doing so, the inner surface of the first inner diameter portion of the outer joint pipe is pressed against the outer surface of the second outer diameter portion of the inner joint pipe.

(8) Furthermore, the steel pipe joint structure according to the present invention is provided with a bolt insertion hole in the first inner diameter portion of the outer joint pipe,
Corresponding to the bolt insertion hole, a bolt screw hole is provided in the second outer diameter portion of the inner joint pipe,
When joining the inner joint pipe to the outer joint pipe, a fastening bolt inserted through the bolt insertion hole is screwed into the bolt screw hole so that the inner surface of the first inner diameter portion of the outer joint pipe is in the inner side. The outer surface of the second outer diameter portion of the joint pipe is pressed.

  (9) Furthermore, the steel pipe joint structure according to the present invention is such that the inner surface of the first outer diameter portion of the inner joint pipe and the inner surface of the other steel pipe are formed by inclined surfaces formed in a predetermined range near the steel pipe. It is characterized by a smooth connection.

  (10) Further, the joint structure of the steel pipe according to the present invention is substantially formed by an inclined surface in which the inner surface of the second inner diameter portion of the outer joint pipe and the inner surface of the one steel pipe are formed in a predetermined range near the steel pipe. It is connected smoothly.

(11) Furthermore, the steel pipe joint structure according to the present invention is provided with two or more engaging portions on the inner surface of the first inner diameter portion of the outer joint pipe,
Engagement protrusions are provided at two or more locations on the outer surface of the second outer diameter portion of the inner joint pipe,
When the outer joint pipe and the inner joint pipe are joined, the engaging projections of the inner joint are substantially in contact with the locking portions of the outer joint pipe, respectively.

Therefore, the steel pipe joint structure according to the present invention has the following effects.
(1) Since the predetermined range of the inner joint pipe has a diameter reducing function, the outer joint pipe and the inner joint pipe can be easily attached and detached, and the workability is improved.
Furthermore, the compressive force acting on the other steel pipe is transmitted to the tip of the outer joint pipe fixed to one steel pipe at the step of the inner joint pipe fixed to the other steel pipe, and the tensile force acting on the other steel pipe is applied. The force is transmitted to the engaging portion of the outer joint pipe fixed to one steel pipe at the engagement protrusion of the inner joint pipe fixed to the other steel pipe. The horizontal force (shearing force) acting on the other steel pipe is transmitted to the first inner diameter portion of the outer joint pipe fixed to one steel pipe in the cylindrical part of the inner joint pipe fixed to the other steel pipe. . Therefore, predetermined strength and rigidity are ensured, and durability and reliability of the joint structure of the steel pipe are guaranteed.

  (2) Further, since the diameter reducing function is a simple structure provided by a plurality of divided pieces, in addition to the effect of (1), the manufacturing cost can be suppressed at a low cost.

  (3) Since the outer surface of the third outer diameter portion of the inner joint pipe is pressed by the bolt on the inner surface of the second inner diameter portion of the outer joint pipe, an external force greater than the pressing force does not act. The tensile force generated inside the bolt does not fluctuate. That is, since the axial force of the bolt does not fluctuate, the fastening bolt does not loosen, and the durability and reliability of the steel pipe joint structure are further improved.

  (4) Further, a bolt insertion hole is provided in the second inner diameter portion of the outer joint pipe, and a bolt screw hole is provided in the third outer diameter portion of the inner joint pipe corresponding to the bolt insertion hole. In addition to the same effects as the above (3), the structure is simple and the construction is easy.

  (5) Further, instead of the inner joint pipe, the predetermined range of the outer joint pipe has a diameter expanding function, so that the same effect as the above (1) can be obtained.

  (6) Furthermore, since the diameter expansion function is a simple structure provided by a plurality of divided pieces, in addition to the effect of (5), the manufacturing cost can be suppressed at a low cost.

  (7) Also, since the inner surface of the first inner diameter portion of the outer joint pipe is pressed against the outer surface of the second outer diameter portion of the inner joint pipe by a bolt, unless an external force greater than the pressing force is applied. Since the axial force of the bolt does not fluctuate, the fastening bolt does not loosen, which further improves the durability and reliability of the steel pipe joint structure.

  (8) Further, a bolt insertion hole is provided in the first inner diameter portion of the outer joint pipe, and a bolt screw hole is provided in the second outer diameter portion of the inner joint pipe corresponding to the bolt insertion hole. In addition to the same effects as the above (7), the structure is simple and the construction is easy.

  (9) Further, the inner surface of the inner joint pipe near the steel pipe and the inner surface of the other steel pipe, and the inner face of the outer joint pipe near the steel pipe and the inner surface of the one steel pipe are respectively inclined surfaces (substantially conical surfaces). The same between the inner joint pipe and the other steel pipe and between the outer joint pipe and the one steel pipe. Therefore, durability and reliability of the joint structure of the steel pipe are further improved.

  (10) Further, since the third inner diameter portion having a small inner radius (the same as the thick wall) is provided near the steel pipe of the outer joint pipe, the rigidity of the outer joint pipe is improved, and the steel pipe of the third inner diameter section is also provided. The close inner surface and the inner surface of one of the steel pipes are each smoothly connected to each other by an inclined surface (same as a substantially conical surface), so that force transmission between the outer joint pipe and one of the steel pipes is smooth. Become. Therefore, durability and reliability of the joint structure of the steel pipe are further improved.

  (11) Furthermore, when the outer joint pipe and the inner joint pipe are joined, two or more places are almost in contact with each other, and a tensile force is transmitted at the two or more places. The burden of Therefore, the design of the shape of the locking part and the engaging protrusion (including the added locking part and the added engaging protrusion) and the degree of freedom in selecting the material forming the outer joint pipe and the inner joint pipe Therefore, the manufacturing cost is reduced, and the durability and reliability of the joint structure are improved.

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same or corresponding portions are denoted by the same reference numerals, and a part of the description is omitted. In addition, “a, b,...” Added to the reference numerals are parts for distinguishing each part having a characteristic difference in part while having parts corresponding to each other. ing.

[Embodiment 1]
FIG. 1 is a schematic view showing a part of a joint structure of a steel pipe according to Embodiment 1 of the present invention in cross section. In FIG. 1, J is a joint part for joining two steel pipes 31 and 32, the bottom is a cylindrical outer joint pipe 1 welded to one steel pipe 31 to be joined, and the top is the other. It consists of a cylindrical inner joint pipe 11 welded to a steel pipe 32.

(Outer joint pipe)
The outer joint pipe 1 is formed so that the outer radius is substantially equal to the outer radius of the steel pipe 31, and the inner peripheral edge of the tip portion 2 is cut obliquely upward to be provided with an inclined surface 3 (same as C chamfering).
A first inner diameter portion 8 having an inner radius R <b> 1 is formed continuously with the inclined surface 3. The first inner diameter portion 8 extends from the distal end portion 2 to a depth h1, and below the first inner diameter portion 8 (the same as the steel pipe 31), the recessed portion 4 (hereinafter referred to as “first”) expanded to an inner radius R2 within a predetermined range. The second inner diameter portion 4 ”is formed, and a third inner diameter portion 9 having an inner radius R3 is formed below the second inner diameter portion 4.
That is, the locking portion 5 is formed at the step portion between the first inner diameter portion 8 and the second inner diameter portion 4, and the protruding step portion 6 is formed at the step portion between the second inner diameter portion 4 and the third inner diameter portion 9. Yes.
Further, a plurality of bolt insertion holes 7 are provided in the second inner diameter portion 4, and a cone that smoothly and smoothly connects the inner surface of the steel pipe pile 31 and the inner surface of the outer joint pipe 1 in a range near the steel pipe of the third inner diameter portion 9. A trapezoidal inclined surface 9a is provided.

At this time, the inner radius R1 is smaller than the inner radius R2 (R1 <R2), the inner radius R1 is the outer radius r2 of the second outer diameter portion of the inner joint pipe 11 described later, and the inner radius R2 is the inner joint described later. The inner radius is substantially equal to the outer radius r3 of the third outer diameter portion of the tube 11.
Further, the distance between the tip portion 2 and the protruding step portion 6 is referred to as a depth h0, and the distance between the tip portion 2 and the locking portion 5 is referred to as a body depth h1.
Note that the third inner diameter portion 9 may be removed and the second inner diameter portion 4 and the inner surface of the steel pipe 31 may be connected approximately smoothly by an inclined surface.

1 shows a case where the inner radius R1 of the first inner diameter portion 8 of the outer joint pipe 1 does not vary in the axial direction, that is, a case where the inner surface is cylindrical, the present invention is limited to this. Instead, the inner radius R1 may vary in the axial direction.
That is, as the first inner diameter portion 8 of the outer joint pipe 1 approaches the second inner diameter portion 4, the diameter is reduced, or the range adjacent to the second inner diameter portion 4 protrudes inward, and the tip 2 of the first inner diameter portion 8 is formed. When the inner radius of the adjacent position (hereinafter referred to as “R1 destination”) is larger than the inner radius of the position adjacent to the second inner diameter portion 4 of the first inner diameter portion 8 (hereinafter referred to as “R1 element”), “R1 First> R1 element "and there is a relationship of"R2> R1 element ".
Further, when the inner radius R2 of the second inner diameter portion 4 varies in the axial direction and the inner radius of the second inner diameter portion 4 adjacent to the first inner diameter portion 8 is “R2 destination”, “R2 destination> R1” The original relationship.

(Inner joint pipe)
The inner joint pipe 11 is provided with a first outer diameter portion 12 having an outer radius r1 that is substantially equal to the outer radius of the steel pipe 32 at the upper portion, and is smaller than the outer radius r1 near the tip of the first outer diameter portion 12. A second outer diameter portion 14 having an outer radius r2 that is an outer radius is provided, and a third outer diameter portion 17 having an outer radius r3 that is larger than the outer radius r2 is provided near the tip of the second outer diameter portion 14, respectively. ing.
A step portion 13 is formed at the step portion between the first outer diameter portion 12 and the second outer diameter portion 14, and the engaging protrusion 16 is formed at the step portion between the second outer diameter portion 14 and the third outer diameter portion 17. The tip portion 20 and the third outer diameter portion 17 are continuous in a substantially conical shape by an inclined surface 19 (same as C chamfering).

Further, an inclined surface 12a is provided on the inner surface of the first outer diameter portion 12 in a range close to the steel pipe, and the inner surface of the first outer diameter portion 12 of the inner joint pipe 11 and the inner surface of the steel pipe 32 are connected approximately smoothly. is doing.
At this time, each outer radius has a relationship of “r1> r2 and r3> r2”. Further, the axial length of the second outer diameter portion 14, that is, the distance between the step portion 13 and the engaging projection 16 is the main body length h2, and the distance between the step portion 13 and the tip portion 20 is the insertion length h3. Called.

1 shows a case where the outer radius r2 of the second inner diameter portion 14 of the inner joint pipe 11 does not vary in the axial direction, that is, a case where the outer surface is cylindrical, the present invention is limited to this. Instead, the outer radius r2 may vary in the axial direction.
That is, as the second outer diameter portion 14 of the inner joint pipe 11 approaches the third outer diameter portion 17, the diameter is reduced, or the range adjacent to the third outer diameter portion 17 is recessed inward, and the second outer diameter portion The outer radius of the position adjacent to the first outer diameter portion 14 (same as the outer radius of the cylindrical portion 22, hereinafter referred to as “r2 element”) is the outer radius of the position adjacent to the third outer diameter portion 17 (hereinafter referred to as “r2 element”). Larger than “r2 destination”), “r2 source> r2 destination” and “r3> r2 destination”.
Furthermore, when the outer radius r3 of the third outer diameter portion 17 varies in the axial direction and the outer radius of the third outer diameter portion 17 adjacent to the second outer diameter portion 14 is “r3 element”, “r3 The relationship is “source> r2 destination”.

(Inner joint pipe slit)
The second outer diameter portion 14 of the inner joint pipe 11 is a cylindrical portion 22 having a predetermined range (a predetermined range from the stepped portion 13, the cross section being indicated by a double oblique line in the drawing) close to the steel pipe. The second outer diameter portion and the third outer diameter portion 17 that are formed and closer to the tip than the cylindrical portion 22 are divided into a plurality of divided pieces 21 by slits 15 that are processed at substantially equal intervals in the circumferential direction. .
That is, the cylindrical portion 22 indicates a range of a distance h5 (hereinafter referred to as “cylindrical portion height”) from the step portion 13 of the second outer diameter portion. Moreover, since the slit 15 is processed into the range of the second outer diameter portion excluding the cylindrical portion 22 and the third outer diameter portion, the slit length h4 is obtained by subtracting the cylindrical portion height h5 from the insertion length h3. Length (h4 = h3-h5).
A bolt screw hole 18 is provided at a position adjacent to the tip of the split piece 21 at a position corresponding to the bolt insertion hole 7 provided in the outer joint pipe 1.

(Relationship between outer joint pipe and inner joint pipe)
The depth h0 of the outer joint pipe 1 is longer than the insertion length h3 of the inner joint pipe 11, and the body depth h1 of the outer joint pipe 1 is set to be substantially equal to the body length h2 of the inner joint pipe 11. .
The inner radius R1 of the first inner diameter portion 8 of the outer joint pipe 1 is set to the outer radius r2 of the second outer diameter portion 14 of the inner joint pipe 11, and the inner radius R2 of the second inner diameter portion 4 of the outer joint pipe 1 is set to the inner side. It is substantially the same as the outer radius r3 of the third outer diameter portion 17 of the joint pipe 11.
Furthermore, when the inner radius R1 of the first inner diameter portion 8 of the outer joint pipe 1 or the outer radius r2 of the second inner diameter section 14 of the inner joint pipe 11 varies in the axial direction, the first inner diameter portion of the outer joint pipe 1 8 is the inner radius of the position adjacent to the first outer diameter portion 12 of the second outer diameter portion 14 of the inner joint pipe 11, that is, the outer radius of the cylindrical portion 22. It is substantially the same as “r2 element”.

(Construction procedure)
2-4 is a schematic diagram explaining an example of the construction procedure which constructs the joining structure of a steel pipe. The steel pipes to be joined are the steel pipe piles 31a and 32a, and the outer joint pipe 1 and the inner joint pipe 11 are previously welded and joined to the respective end portions at a factory or the like (referred to as "fixed" in the present invention, These steel pipe piles 31a and 32a shall be transported to the construction site.

  In FIG. 2A, first, a steel pipe pile 31a to which the outer joint pipe 1 is fixed is driven into the ground. When the driving progresses and the upper steel pipe pile 32a is connected, the steel pipe pile 32a having the inner joint pipe 11 fixed at the tip is conveyed and positioned on the steel pipe pile 31a.

  In FIG. 2B, the steel pipe pile 32a is lowered by a rolling force due to its own weight or the like. At this time, the inclined surface 3 (a part of a substantially conical surface extending upward in the figure) provided on the inner peripheral side of the distal end portion 2 of the outer joint pipe 1 is the third outer diameter portion of the inner joint pipe 11. 17 guides an inclined surface 19 (a part of a substantially conical surface that shrinks downward in the figure) provided at the lower part of the lower part 17, so that the lowering is easy, and the third outer diameter portion 17 of the inner joint pipe 11 is It enters the first inner diameter portion 8 of the outer joint pipe 1.

  In FIG. 3C, when the steel pipe pile 32a is continuously lowered, the third outer diameter portion 17 of the inner joint pipe 11 slides on the inner surface of the first inner diameter section 8 of the outer joint pipe 1, and the divided piece 21 Is bent toward the axial center, and the third outer diameter portion 17 is reduced in diameter. That is, one end of the split piece 21 is supported by the cylindrical portion 22 and behaves as a “cantilever”.

In FIG. 4 (d), when the inner joint pipe 11 is further lowered, the third outer diameter portion 17 is disengaged from the first inner diameter section 8 of the outer joint pipe 1. At this time, the bent segment 21 is elastically restored toward the second inner diameter portion 4 of the outer joint pipe 1, and the engagement protrusion 16 of the inner joint pipe 11 is locked to the locking portion 5 of the outer joint pipe 1. To do.
Then, the descent stops when the stepped portion 13 of the inner joint pipe 11 comes into contact with the tip 2 of the outer joint pipe 1. At this time, since the depth h0 of the outer joint pipe 1 is larger than the insertion length h3 of the inner joint pipe 11, there is a gap between the protruding step portion 6 of the outer joint pipe 1 and the distal end portion 20 of the inner joint pipe 11. Is ensured so that they do not come into contact with each other.
Further, the outer surface of the cylindrical upper portion 22 of the inner joint pipe 11 and the inner surface of the first inner diameter portion 8 of the outer joint pipe 1 are in contact with each other through a slight gap (this state is “substantially in contact”). Called).
Further, since the main body depth h1 of the outer joint pipe 1 is slightly larger than the main body length h2 of the inner joint pipe 11 and is substantially the same, the engagement protrusion between the locking portion 5 of the outer joint pipe 1 and the inner joint pipe 11 is the same. The part 16 is in contact with, or substantially in contact with, through a slight gap.

  In FIG. 4 (e), if a bolt 35, which is a diameter expanding means, is inserted into the bolt insertion hole 7 of the outer joint pipe 1 and screwed into the bolt screwing hole 18 of the inner joint pipe 11, then tightened. The split piece 21 of the inner joint pipe 11 is attracted to the bolt 35, and the outer surface of the third outer diameter portion 17 is pressed against the inner surface of the second inner diameter portion 4. This process completes the joining.

(Power transmission)
The force (compression force) that presses the steel pipe pile 31a and the steel pipe pile 32a in the axial direction in the joining structure of the steel pipe joined by the above construction procedure is the step between the tip 2 of the outer joint pipe 1 and the inner joint pipe 11. It is transmitted in the contact area with the part 13.
Moreover, the force (pulling force) that separates the steel pipe pile 31a and the steel pipe pile 32a in the axial direction is transmitted in the contact range between the engaging portion 5 of the outer joint pipe 1 and the engaging protrusion 16 of the inner joint pipe 11. The
Further, the force for separating the steel pipe pile 31a and the steel pipe pile 32a in the direction perpendicular to the axial direction (the same as the shearing force acting in the horizontal direction) is the same as the inner surface of the first inner diameter portion 8 of the outer joint pipe 1 and the inner joint pipe 11. Is transmitted in a contact range with the outer surface of the cylindrical portion 22 (same as the outer surface of the second outer diameter portion 14). At this time, the amount of eccentricity between the steel pipe pile 31a and the steel pipe pile 32a (the amount of deviation in the horizontal direction of the respective shaft centers) can be kept small. That is, assuming that the slit is machined in the entire length of the second outer diameter portion 14, the sectional rigidity (second moment of section) of the divided piece formed by the full length slit is compared with the sectional rigidity of the cylindrical portion 22. Since the value is much smaller, the shearing force is transmitted by a slight deviation by forming the cylindrical portion 22.

Moreover, the inner surface of the steel pipe pile 31a and the inner surface of the third inner diameter portion 9 of the outer joint pipe 1 are substantially continuous by the truncated cone-shaped inclined surface 9a, and the inner surface of the steel pipe pile 32a and the first outer diameter of the inner joint pipe 11 Since the inner surface of the part 12 is substantially continuous by the truncated cone-shaped inclined surface 12a, the flow of force between the steel pipe pile 31a and the outer joint pipe 1 and between the steel pipe pile 32a and the inner joint pipe 11 Is smooth.
Further, since the outer radii of the steel pipe pile 31a, the outer joint pipe 1, the first outer diameter portion 12 of the inner joint pipe 11, and the steel pipe pile 32a are substantially the same, when these are joined and driven into the ground Since the joint is smooth (no irregularities), it is easy to drive.
Furthermore, the third inner diameter portion 9 of the outer joint pipe 1 has an inner radius smaller than the inner radius of the second inner diameter portion 4 and has a thick wall, so that the rigidity is increased. Note that the third inner diameter portion 9 may be removed, and the inner surface of the second inner diameter portion 4 and the inner surface of the steel pipe pile 31a may be connected approximately smoothly by an inclined surface.

(Force acting on the bolt)
FIG. 5 is a schematic diagram for explaining the force acting on the bolt in the steel pipe joining structure. In FIG. 5 (a), when a force (tensile force) for separating the outer joint pipe 1 (same as the steel pipe pile 31a) and the inner joint pipe 11 (same as the steel pipe pile 32a) in the axial direction is applied, that is, divided When the tensile force T acts on the piece 21, the tensile force T is transmitted in the contact range between the engaging portion 5 of the outer joint pipe 1 and the engaging protrusion 16 of the inner joint pipe 11 as described above.
At this time, since the position where the pulling force T acts and the outer contact range are not collinear, the amount of the deviation is the “bending moment arm”, and the bending moment (in the figure, (Indicated by arrow M) occurs. That is, the third outer diameter portion 17 of the split piece 21 tends to fall in the axial direction with the corresponding contact range as a fulcrum.

In FIG. 5B, the vertical axis represents the axial force P generated inside the bolt 35, and the horizontal axis represents the tensile force T acting on the divided piece 21, showing the relationship between the two.
That is, as described in the construction procedure described above, the bolt 35 presses the outer surface of the third outer diameter portion 17 against the inner surface of the second inner diameter portion 4, so that no tensile force acts on the split piece 21 (T = 0), the axial force Pb generated inside the bolt 35 is the same as the pressing force q (compression force of the surface contact portion).

When the tensile force T in the axial direction acts on the split piece 21, a bending moment is generated as described above, and the third outer diameter portion 17 of the split piece 21 tends to fall in the axial direction. The pressing force q (compression force) is reduced by an amount corresponding to (indicated by a dashed line in the figure). However, since the bending moment is absorbed as a decrease in the absolute value of the pressing force q (compression force), the axial force Pb generated inside the bolt 35 does not vary (in the drawing, (Indicated by solid line). Therefore, the bolt 35 is difficult to loosen.
When the pulling force T becomes excessive and the outer surface of the third outer diameter portion 17 and the inner surface of the second inner diameter portion 4 are separated from each other, the alternate long and short dash line indicating the pressing force q overlaps the horizontal axis (q = 0), a portion corresponding to the tensile force ΔT that increases after the separation acts as a variable axial force ΔP added to the axial force Pb generated in the bolt 35.

(Other example 1)
FIG. 6 is an explanatory diagram of another example of the first embodiment. In FIG. 6, the range close to the second inner diameter portion 4 of the inner radius of the first inner diameter portion 8a of the outer joint pipe 1a is reduced in diameter (according to the above description, R1 point> R1 element), and corresponds to the reduced diameter. Thus, the outer radius of the second outer diameter portion 14a of the inner joint pipe 11a is also reduced in diameter in the range close to the third outer diameter portion 17 (r2 origin> r2 destination according to the above description).
That is, when there is no diameter reduction, the depth of the locking portion 5a is “R2−R1” which is the difference between the radius of the outer corner of the locking portion 5a and the radius of the inner angle of the locking portion 5a. Due to such a reduction in diameter, it increases to “R2 point-R1 element”, and similarly, the depth of the engagement protrusion 16a of the inner joint pipe 11a is set to the radius of the outer angle of the engagement protrusion 16a and the engagement protrusion 16a. The difference from the radius of the inner corner “r3−r2” is increased to “r3 element−r2 destination” due to the reduced diameter.

Therefore, since the area which transmits the tensile force which the steel pipe pile 31a, 31a acts increases, the damage of the said part is prevented, the freedom degree of design and material selection of the outer joint pipe 1a and the inner joint pipe 11a increases, and manufacture Cost is reduced.
The form of the reduced diameter is not limited. For example, even if the tapered surface (conical surface) is smooth over the entire body depth (h1) and body length (h2), It may be a local protrusion or recess formed by a combination with a conical surface. Further, the inner radius R2 of the second inner diameter portion 4 may be smaller than the inner radius “R1 tip” at the tip of the first inner diameter portion 8a of the outer joint pipe 1a, or both may be the same.

  Further, in the second outer diameter portion 14a of the inner joint pipe 11a, the inner radius of the divided piece 21a is larger than the inner radius of the cylindrical portion 22 (the thickness of the divided piece 21a is smaller than the thickness of the cylindrical portion 22). The split piece 21a is easily bent. Note that the difference between the inner radii in consideration of the bending of the split piece 21a at the time of attachment and detachment, the transmission of the above-described shearing force in the cylindrical portion 22, the inflow of the tensile force from the split piece 21a to the cylindrical portion 22, etc. The amount can be selected as appropriate, and both inner radii may be the same. Furthermore, the thickness of the split piece 21a is not limited to a uniform one in the length direction (the same in the vertical direction in the figure), and may vary in a tapered shape.

Further, the bolt insertion hole 7 provided in the outer joint pipe 1 is provided with a seat 7a (a recess having a large inner diameter). Accordingly, when the bolt 35 is installed, the amount of the head of the bolt 35 protruding from the outer surface of the outer joint pipe 1a is reduced or no longer protrudes, so that the penetration resistance when the steel pipe piles 31a and 32a are driven into the ground is reduced. This improves the workability. If a hexagon socket head bolt is used as the bolt 35, the inner diameter of the seat 7a can be reduced.
Further, instead of the bolt screw hole 18 of the inner joint pipe 11, a bolt insertion hole through which the bolt 35 can be inserted is provided, and a nut screwed to the bolt 35 is welded and joined to the inner surface of the third outer diameter portion 17. Good.

(Other example 2)
7 to 9 are explanatory diagrams of other examples of the first embodiment. In FIG. 7, the inner joint pipe 11b is provided with a concave portion 23b having a rectangular cross section on the inner side of a predetermined range from the root of the split piece 21b, that is, the cylindrical portion 22 (same as the bottom of the slit 15). .
In FIG. 8, the inner joint pipe 11c is provided with a recess 23c having an arc-shaped cross section on the outer surface side at a position a predetermined distance from the root of the split piece 21c. That is, the base of the split piece 21c has the same thickness as that of the cylindrical portion 22, and the thickness gradually decreases from a position slightly entering the tip side from the root, and once it reaches the minimum thickness, the thickness is increased again. Increasingly.
In FIG. 9, the inner joint pipe 11 d is provided with a through hole 15 d at the bottom of the slit 15. That is, since the width of the slit 15 is increased by the approximate radius of the through hole 15d at the joint portion with the cylindrical portion 22, the width of the divided piece 21d is decreased by the approximate diameter of the through hole 15d.

Accordingly, when the inner joint pipes 11b, 11c, or 11d are attached to or detached from the outer joint pipe 1, the split pieces 21b, 21c, and 21d are all reduced in bending rigidity (secondary moment of section) at a position where the bending moment is large. Therefore, it is easy to bend. For this reason, the force required for press-fitting is reduced, and even with a large-diameter joint J, due to the weight of the steel pipe pile 32a (disposed above) fixed to the inner joint pipe 11b, 11c, or 11d, etc., The inner joint pipe 11b, 11c, or 11d can be press-fitted into the inner periphery of the outer joint pipe 1.
Therefore, even if the joint portion J has a large diameter, it is not necessary to lengthen the axial length of the split piece 21 (same as the slit length h4, see FIG. 1) to make it easy to bend. It can be reduced in size, can be reduced in weight, and an increase in manufacturing cost can be suppressed. Moreover, since it is not necessary to use a press-fitting machine etc. even if it is the large diameter coupling part J, it becomes possible to hold down construction cost cheaply because work is easy.

  The recesses 23b and 23c and the through holes 23d are examples, and the position, shape, and size (length and depth) are design matters that can be appropriately selected and combined. For example, the concave portion 23b may be provided by moving from the base to the tip side by a predetermined distance, or may be provided on the outer surface instead of the inner surface, or the rectangular cross section may be a cross section made of a smooth curve. Moreover, you may make the thickness of the division | segmentation piece 21b, 21c, 21d different from the thickness of the cylindrical part 22 (refer FIG. 6).

(Other example 3)
10 and 11 are explanatory diagrams of another example of the present embodiment. 10 and 11, the outer joint pipe 1e is provided with a bolt screwing hole 7e instead of the bolt insertion hole 7, and the third outer diameter portion 17e of the inner joint pipe 11e is replaced with the bolt screwing hole 18. An inverted U-shaped fitting groove 18e opened at the tip is provided, and a locking groove 36e for rotating the bolt 35e from the tip side (for example, a minus groove (−) is provided at the tip of the screw part of the bolt 35e. Groove), plus groove (+ groove), hexagonal hole, etc.).

Therefore, when the steel pipe pile 31a to which the outer joint pipe 1e is fixed is driven into the ground and the steel pipe pile 32a (not shown) is connected to this, the bolt hole 7e of the outer joint pipe 1e is inserted into the bolt hole 7e. The tip of the bolt 35e is screwed from the inside (see (a) of FIG. 11).
Then, the steel pipe pile 32a to which the inner joint pipe 11e is fixed is lowered by a rolling force due to its own weight or the like. At this time, since the position of the bolt 35e of the outer joint pipe 1e and the position of the fitting groove 18e of the inner joint pipe 11e are matched, the bolt 35e is accommodated in the fitting groove 18e ((b) of FIG. 11). reference).

Next, when the bolt 35e is further tightened by engaging an engaging groove 36e provided at the tip of the bolt 35e from the outside of the outer joint pipe 1e, for example, the segment 21e of the inner joint pipe 11e becomes the bolt The head of 35e is pulled toward the outer joint pipe 1e side.
That is, the inner surface of the second inner diameter portion 4e of the outer joint pipe 1e and the outer surface of the third outer diameter portion 17e of the inner joint pipe 11e are pressed against each other. Further, the length under the neck of the bolt 35e is substantially the same as the sum of the thickness of the second inner diameter portion 4e of the outer joint pipe 1e and the thickness of the third outer diameter portion 17e of the inner joint pipe 11e. Since the tip of the bolt 35e does not protrude from the outer surface of the outer joint pipe 1e, the bolt 35e does not become a resistance when the steel pipe piles 31a and 32a are driven into the ground (see FIG. 11C).

(Other example 4)
FIG. 12 is an explanatory diagram of an example in which the locking portion and the engaging protrusion are provided at two or more locations in the present embodiment. In FIG. 12, an additional locking portion 5f that is recessed in an annular shape is formed on the inner surface of the first inner diameter portion 8f of the outer joint pipe 1f, while the inner side is located at a position corresponding to the added locking portion 5f. An additional engaging protrusion 16f that protrudes is formed on the outer surface of the second outer diameter portion 14f of the joint pipe 11f.
Therefore, when the inner joint pipe 11f is press-fitted into the outer joint pipe 1f, the third outer diameter portion 17 of the inner joint pipe 11f does not fall into the added locking portion 5f of the outer joint pipe 1f, and the outer joint pipe 1f It reaches the second inner diameter part 4. At this time, the engaging protrusion 16 of the inner joint pipe 11f abuts against the engaging part 5 of the outer joint pipe 1f or confronts (that is, substantially abuts) via a slight gap. The added engaging protrusion 16f abuts against or is opposed to the added engaging portion 5f of the outer joint pipe 1f via a slight gap.

Therefore, the force (pulling force) for separating the steel pipe pile 31a and the steel pipe pile 32a in the axial direction is the contact range between the engaging portion 5 of the outer joint pipe 1f and the engagement protrusion 16 of the inner joint pipe 11f, and the outer side. Since the transmission is performed in the contact range between the additional locking portion 5f of the joint pipe 1f and the additional engagement protrusion 16f of the inner joint pipe 11f, the area for transmitting the tensile force increases. Therefore, the damage of the said part is prevented, the freedom degree of design and material selection of the outer joint pipe 1f and the inner joint pipe 11f increases, and manufacturing cost reduces.
The number and shape of the added locking portion 5f and the added engagement protrusion 16f are not limited to those shown in the figure, and may be 1 or 2 or more. Even if it is the same shape and size as the protrusion 16, it may be a different shape and size. Further, an additional locking portion that protrudes from the inner surface of the second inner diameter portion 4 of the outer joint pipe 1 is formed, and on the other hand, a third outer diameter of the inner joint pipe 11 corresponding to the added locking portion. The same action and effect can be obtained by forming an additional engaging projection that is recessed on the outer surface of the portion 17.

[Embodiment 2]
FIG. 13: is the schematic diagram which showed a part in cross section explaining the joint structure of the steel pipe which concerns on Embodiment 2 of this invention. In the second embodiment, the slit 15g is formed in the outer joint pipe 1g to form the split piece 41, and the outer joint pipe 1g is provided with a diameter expanding function. This is different from the first embodiment in which the tube 11 has a diameter reducing function.

(Outer joint pipe)
A plurality of bolt insertion holes 7 are provided in the first inner diameter portion 8g of the outer joint pipe 1g.
Further, the second inner diameter portion 4g forms a cylindrical portion 42 (a cross section is indicated by a double oblique line in the drawing) in which a predetermined range (same as the predetermined range from the protruding step portion 6) near the steel pipe is formed, A range closer to the tip than the cylindrical portion 42 of the second inner diameter portion 4g and the first inner diameter portion 8g are divided into a plurality of divided pieces 41 by slits 15g processed at substantially equal intervals in the circumferential direction.
That is, the slit 15g reaches the distal end portion 2 from a predetermined position of the second inner diameter portion 4g, and the range of the slit length h4, which is the distance from the bottom of the slit 15g to the distal end portion 2, forms a plurality of divided pieces 41 and protrudes. The range from the step 6 to the bottom of the slit 15g (the range of the cylindrical portion height h7 (h7 = h0−h4), which is the depth obtained by subtracting the slit length h4 from the depth h0) forms the cylindrical portion 42. is doing.

(Inner joint pipe)
The inner joint pipe 11g is obtained by removing the slit 15 from the inner joint pipe 11 in the first embodiment and providing a bolt screw hole 18 in the second outer diameter portion 14.

(Construction procedure)
14 and 15 are schematic diagrams for explaining an example of a construction procedure for constructing a steel pipe joint structure according to the present invention.
First, when the steel pipe pile 31a to which the outer joint pipe 1g is joined is driven to a state where the upper steel pipe pile 32a is joined, the steel pipe pile 32a to which the inner joint pipe 11g is joined is positioned above the steel pipe pile 31a. Then, the steel pipe pile 32a is lowered by a rolling force caused by its own weight or the like (see (a) of FIG. 14).

  Then, when the steel pipe pile 32a is continuously lowered, the inclined surface 19 provided at the distal end portion 20 of the inner joint pipe 11g is guided to the inclined surface 3 provided at the distal end portion 2 of the outer joint pipe 1g, and further, the outer joint pipe 1g. Since the outer surface of the third outer diameter portion 17 of the inner joint pipe 11g slides on the inner surface of the first inner diameter section 8g to bend the split piece 41 of the outer joint pipe 1g, the first inner diameter section 8g expands. . Therefore, the third outer diameter portion 17 of the inner joint pipe 11g enters the first inner diameter section 8g of the outer joint pipe 1g (see FIG. 14B).

Further, when the steel pipe pile 32a is lowered, the outer surface of the third outer diameter portion 17 of the inner joint pipe 11g is lowered along the inner surface of the first inner diameter part 8g of the outer joint pipe 1g, and the split piece 41 of the outer joint pipe 1g. Further bends and expands in diameter. That is, one end of the split piece 41 is supported by the cylindrical portion 42 and behaves as a “cantilever”.
Eventually, since the third outer diameter portion 17 of the inner joint pipe 11g is disengaged from the first inner diameter section 8g of the outer joint pipe 1g, the split piece 41 is elastically restored (reduced diameter) toward the second outer diameter 14 of the inner joint pipe 11g. ), And the engaging portion 5 of the outer joint pipe 1g is engaged with the engaging protrusion 16 of the inner joint pipe 11g.
And when the front-end | tip part 20 of the inner joint pipe 11g contacts the protrusion step part 6 of the outer joint pipe 1g, the descent stops. At this time, the inner surface of the cylindrical portion 42 of the outer joint pipe 1g and the outer surface of the third outer diameter portion 17 of the inner joint pipe 11g are in contact with each other, that is, substantially in contact with each other through a slight gap.
Further, since the main body depth h1 of the outer joint pipe 1g is slightly larger than the main body length h2 of the inner joint pipe 11g and is substantially the same, the engagement protrusion 5 of the outer joint pipe 1g and the inner joint pipe 11g is engaged. It abuts against the part 16 or is opposed through a slight gap, that is, substantially abuts (see (c) of FIG. 14).

  In this state, the bolt 35 which is a diameter reducing means inserted into the bolt insertion hole 7 (partially not shown) of the outer joint pipe 1g is inserted into the bolt screw hole 18 (partially not shown) of the inner joint pipe 11g. When screwed in and tightened, the split piece 41 of the outer joint pipe 1g is drawn to the bolt 35 to reduce its diameter, and the inner surface of the first inner diameter part 8g of the split piece 41 is the second outer diameter part 14 of the inner joint pipe 11g. Is pressed against the outer surface (see FIG. 15). This process completes the joining.

(Power transmission)
Therefore, since the same effects as those of the first embodiment can be obtained in the second embodiment, the joint structure is manufactured at low cost, and good workability and high reliability are ensured.
That is, the force (compression force) that presses the steel pipe pile 31a and the steel pipe pile 32a in the axial direction is transmitted in the contact range between the protruding step portion 6 of the outer joint pipe 1g and the tip portion 20 of the inner joint pipe 11g. .
Moreover, the force (pulling force) which separates the steel pipe pile 31a and the steel pipe pile 32a in the axial direction is transmitted in the contact range between the engaging portion 5 of the outer joint pipe 1g and the engaging protrusion 16 of the inner joint pipe 11g. The
Moreover, the force (shearing force which acts in a horizontal direction) which separates the steel pipe pile 31a and the steel pipe pile 32a in the direction perpendicular to the axial direction is the third inner surface of the inner joint pipe 11g and the inner face of the inner joint pipe 11g. It is transmitted in a contact range with the outer surface of the outer diameter portion 17.

Further, the bolt 35 presses the inner surface of the first inner diameter portion 8g of the outer joint pipe 1g (the same as the inner surface of the divided piece 41) against the outer surface of the second outer diameter portion 14 of the inner joint pipe 11g. Even if an axial pulling force is applied to 41, the axial force generated inside the bolt 35 does not fluctuate and is difficult to loosen.
Further, in the second embodiment, similarly to the first embodiment described above, it is possible to employ the processing of the recesses in the divided pieces, the installation of the fitting grooves 18e, or the use of multiple locking portions and engaging protrusions. it can.

By the way, in Embodiment 1 and Embodiment 2, although the case where this invention was used for the joining of steel pipe piles 31a and 32a was shown as a joining structure of a steel pipe, this invention is not limited to this, Other than a pile It can also be carried out when joining steel pipes.
Further, when the inner joint pipe 11 is press-fitted into the outer joint pipe 1, a press-fitting machine or the like may be used. Furthermore, the positional relationship between the steel pipe piles 31a and 32a or the steel pipes 31 and 32, that is, the positional relationship between the outer joint pipe 1 and the inner joint pipe 11, is not limited. May be at the same height in the direction.

  Since this invention is the above structure, it can utilize widely as a joining structure of the steel pipe which joins a steel pipe without welding.

The schematic diagram of the partial cross section which shows the joint structure of the steel pipe which concerns on Embodiment 1 of this invention. The schematic diagram explaining the construction procedure of the joining structure of a steel pipe. The schematic diagram explaining the construction procedure of the joining structure of a steel pipe (continuation of FIG. 2). The schematic diagram explaining the construction procedure of the joining structure of a steel pipe (continuation of FIG. 3). The schematic diagram explaining the force which acts on the volt | bolt in the joining structure of a steel pipe. Explanatory drawing of the other example 1 of Embodiment 1. FIG. Explanatory drawing of the other example 2 of Embodiment 1. FIG. Explanatory drawing of the other example 2 of Embodiment 1. FIG. Explanatory drawing of the other example 2 of Embodiment 1. FIG. Explanatory drawing of the other example 3 of Embodiment 1. FIG. Explanatory drawing of the other example 3 of Embodiment 1. FIG. Explanatory drawing of the other example 4 (two or more engagement parts and engagement protrusions) of Embodiment 1. FIG. The schematic diagram of the partial cross section explaining the joint structure of the steel pipe which concerns on Embodiment 2 of this invention. The schematic diagram explaining the construction procedure of the joining structure of a steel pipe. The schematic diagram explaining the construction procedure of the joining structure of a steel pipe (continuation of FIG. 14).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer joint pipe 2 Tip part 3 Inclined surface 4 Second inner diameter part 5 Locking part 6 Projection step part 7 Bolt insertion hole 8 First inner diameter part 9 Third inner diameter part 11 Inner joint pipe 12 First outer diameter part 13 Step part 14 Second outer diameter portion 15 Slit 16 Engaging protrusion 17 Third outer diameter portion 18 Bolt screwing hole 19 Inclined surface 20 Tip portion 21 Split piece 22 Cylindrical portion 31 Steel pipe 32 Steel pipe 41 Split piece 42 Cylindrical portion J Joint Part h0 Depth h1 Body depth h2 Body length h3 Insertion length h4 Slit length h5 Cylindrical part height r1 Outer radius of the first outer diameter r2 Outer radius of the second outer diameter r3 Third outer diameter Outer radius R1 inner radius of the first inner diameter R2 inner radius of the second inner diameter R3 inner radius of the third inner diameter

Claims (11)

An outer joint pipe fixed to one steel pipe, and an inner joint pipe fixed to the other steel pipe and detachably joined to the outer joint pipe;
The outer joint pipe has a first inner diameter portion located closer to the tip, a second inner diameter portion located closer to the steel pipe than an inner radius of the first inner diameter portion, and the first inner diameter portion and the second inner diameter. A locking part located between the two parts,
The inner joint pipe has an outer radius larger than an inner radius of the first inner diameter part of the outer joint pipe and is positioned closer to the other steel pipe, and an inner diameter of the first inner diameter part of the outer joint pipe A second outer diameter portion positioned substantially closer to the tip than the first outer diameter portion, substantially the same as the inner radius of the second inner diameter portion, and having the same outer radius as the radius, and the second outer diameter portion A third outer diameter portion located at an outer radius equal to or greater than the outer radius and closer to the tip than the second outer diameter portion; and a step portion located between the first outer diameter portion and the second outer diameter portion; An engagement protrusion positioned between the second outer diameter part and the third outer diameter part, and a cylindrical part in a predetermined range near the steel pipe of the second outer diameter part,
In the range closer to the tip than the cylindrical part of the second outer diameter part of the inner joint pipe and the third outer diameter part, it has a diameter reducing function at the time of attachment and detachment,
When the inner joint pipe is joined to the outer joint pipe, a step portion of the inner joint pipe comes into contact with a tip portion of the outer joint pipe, and an engagement protrusion of the inner joint pipe is engaged with a locking portion of the outer joint pipe. And the outer surface of the tubular portion of the inner joint tube substantially contacts the inner surface of the first inner diameter portion of the outer joint tube. In the diameter reducing function, the range of the second outer diameter portion of the inner joint pipe closer to the tip than the cylindrical portion and the third outer diameter portion are divided into a plurality of divided pieces by slits provided in the axial direction. Being
The steel pipe joint structure according to claim 1, wherein when the inner joint pipe is attached to or detached from the outer joint pipe, the split piece is bent.   When the inner joint pipe is joined to the outer joint pipe, the second inner diameter portion of the outer joint pipe and the third outer diameter portion of the inner joint pipe are fastened with bolts, thereby The steel pipe joint structure according to any one of claims 1 to 2, wherein the outer surface of the third outer diameter portion of the inner joint pipe is pressed against the inner surface of the second inner diameter portion. A bolt insertion hole is provided in the second inner diameter portion of the outer joint pipe,
Corresponding to the bolt insertion hole, a bolt screw hole is provided in the third outer diameter portion of the inner joint pipe,
When the inner joint pipe is joined to the outer joint pipe, a fastening bolt inserted through the bolt insertion hole is screwed into the bolt screwing hole, whereby an inner surface of the second inner diameter portion of the outer joint pipe is joined to the inner side. 3. The steel pipe joint structure according to claim 1, wherein an outer surface of the third outer diameter portion of the joint pipe is pressed. An outer joint pipe fixed to one steel pipe, and an inner joint pipe fixed to the other steel pipe and detachably joined to the outer joint pipe;
The outer joint pipe has a first inner diameter portion located closer to the tip, a second inner diameter portion located closer to the steel pipe than an inner radius of the first inner diameter portion, and the first inner diameter portion and the second inner diameter. A locking portion located between the second inner diameter portion and the projecting step portion located between the second inner diameter portion and the steel pipe, and a cylindrical portion in a predetermined range near the steel pipe of the second inner diameter portion,
The inner joint pipe has an outer radius substantially the same as an inner radius of the first inner diameter part of the outer joint pipe, a second outer diameter part positioned closer to the other steel pipe, and an inner radius of the second inner diameter part, A third outer diameter portion that is substantially the same and has an outer radius that is equal to or greater than the outer radius of the second outer diameter portion and that is positioned closer to the tip than the second outer diameter portion; and the second outer diameter portion and the third outer diameter An engagement protrusion positioned between the diameter portion,
In the range closer to the tip than the cylindrical part of the second inner diameter part of the outer joint pipe and the first inner diameter part, it has a function of expanding the diameter at the time of attachment and detachment.
When the inner joint pipe is joined to the outer joint pipe, the protruding step portion of the outer joint pipe comes into contact with the distal end portion of the inner joint pipe, and the inner joint pipe is engaged with the locking portion of the outer joint pipe. A steel pipe joint structure, wherein the projections are substantially in contact with each other, and the outer surface of the third outer diameter part of the inner joint pipe is substantially in contact with the inner surface of the cylindrical part of the outer joint pipe. In the diameter expansion function, the range of the second inner diameter portion of the outer joint pipe closer to the tip than the cylindrical portion and the first inner diameter portion are divided into a plurality of divided pieces by slits provided in the axial direction. Become
The steel pipe joint structure according to claim 5, wherein when the inner joint pipe is attached to and detached from the outer joint pipe, the split piece is bent.   When joining the inner joint pipe to the outer joint pipe, the inner surface of the first inner diameter part of the outer joint pipe is fastened with a bolt between the outer joint pipe and the second outer diameter part of the inner joint pipe. 7 is pressed against the outer surface of the second outer diameter portion of the inner joint pipe. The steel pipe joint structure according to any one of claims 5 to 6. Bolt insertion holes are provided in the first inner diameter portion of the outer joint pipe,
Corresponding to the bolt insertion hole, a bolt screw hole is provided in the second outer diameter portion of the inner joint pipe,
When joining the inner joint pipe to the outer joint pipe, a fastening bolt inserted through the bolt insertion hole is screwed into the bolt screw hole so that the inner surface of the first inner diameter portion of the outer joint pipe is in the inner side. The steel pipe joint structure according to any one of claims 5 to 6, wherein the outer surface of the second outer diameter portion of the joint pipe is pressed.   The inner surface of the first outer diameter portion of the inner joint pipe and the inner surface of the other steel pipe are substantially smoothly connected by an inclined surface formed in a predetermined range near the steel pipe. 8. A steel pipe joint structure according to any one of 8 above.   10. The inner surface of the second inner diameter portion of the outer joint pipe and the inner surface of the one steel pipe are substantially smoothly connected by an inclined surface formed in a predetermined range near the steel pipe. A steel pipe joint structure according to any one of the above. Locking portions are provided at two or more locations on the inner surface of the first inner diameter portion of the outer joint pipe,
Engagement protrusions are provided at two or more locations on the outer surface of the second outer diameter portion of the inner joint pipe,
11. The structure according to claim 1, wherein when the outer joint pipe and the inner joint pipe are joined, the engagement protrusions of the inner joint substantially come into contact with the locking portions of the outer joint pipe, respectively. A steel pipe joint structure according to any one of the above.

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