WO2023074257A1

WO2023074257A1 - Multiple-step insertion joint, steel pipe with joint, structure, method of constructing structure, and methods of designing and producing multiple-step insertion joint

Info

Publication number: WO2023074257A1
Application number: PCT/JP2022/036757
Authority: WO
Inventors: 雄登大場
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2021-10-29
Filing date: 2022-09-30
Publication date: 2023-05-04
Also published as: JP2023066484A

Abstract

The purpose of the present invention is to provide a multiple-step insertion joint, a steel pipe with a joint, a structure, a method of constructing a structure, and methods of designing and producing a multiple-step insertion joint, which prevent meshing of a projecting part and a recessed part that are not to be engaged with each other during insertion, and which provide good workability during steel pipe joining. A multiple-step insertion joint 1 comprises an inner joint pipe 3 and an outer joint pipe 5. One of the inner joint pipe 3 or the outer joint pipe 5 has a divided cylindrical part 11 composed of a plurality of divided pieces 9, and a projecting part 13 provided in multiple steps on the divided pieces 9. The other has a cylindrical part 17 and a recessed part 19 provided in multiple steps on the cylindrical part 17. Steel pipes 7 are joined by engaging the projecting part 13 with the recessed part 19. The multiple-step projecting part 13 gradually decreases in axial width from the projecting part 13 on a distal end side toward the projecting part 13 on a base end side. The multiple-step recessed part 19 gradually decreases in axial width from the recessed part 19 on a distal end side toward the recessed part 19 on a base end side. The axial width of each projecting part 13 is larger than or equal to the axial width of the recessed part 19 located on the distal end side relative to the recessed part 19 with which the projecting part 13 engages during joint fitting.

Description

Multi-stage insertion joint, steel pipe with joint, structure, construction method for structure, design method and manufacturing method for multi-stage insertion joint

TECHNICAL FIELD The present invention relates to a mechanical joint used to join steel pipes, and more particularly, to a plug-in joint in which an inner joint pipe is inserted into an outer joint pipe for engagement, and which has a multi-stepped engagement portion. The present invention relates to a joint, a steel pipe with a joint, a structure, a method for constructing a structure, and a design method and manufacturing method for a multi-step joint.

As a method of connecting steel pipes in place of welding, many applications have been filed using mechanical joints.
One of the mechanical joints is a plug-in type joint in which an outer joint pipe and an inner joint pipe are provided at the joint ends of the steel pipes to be joined, and the steel pipes are connected by inserting the inner joint pipe into the outer joint pipe. There is An example of such a plug-in joint is disclosed, for example, in US Pat.

The "steel pipe joint structure" disclosed in Patent Document 1 is "a slit formed in one of the outer joint pipe and the inner joint pipe to divide them into a plurality of parts in the circumferential direction, and a convex portion formed on the outer peripheral surface of the inner joint pipe. and an engaging portion that is formed on the inner peripheral surface of the outer joint pipe and engages with the convex portion in a state in which the inner joint pipe is inserted into the outer joint pipe to resist the tensile load together with the convex portion. (See claim 1 of Patent Document 1). Since the inner joint pipe is divided into a plurality of pieces by the slits, each of the divided pieces elastically deforms inward during insertion, and the elastic deformation is restored when the insertion is completed, so that the convex portion of the inner joint pipe becomes the outer joint pipe. engages with the engaging portion of In this state, the connection is completed by inserting the bolts into the bolt holes respectively provided on the proximal end side of the outer joint pipe and the distal end side of the inner joint pipe and tightening them.

Since the convex portion of Patent Document 1 is a portion that resists a tensile load in cooperation with the engaging portion, when a large load is expected or when a large-diameter steel pipe or the like requires a high yield strength, the convex portion It is necessary to improve the resistance to tensile load by, for example, increasing the strength of the part. In order to increase the strength of the projection, the projection may be made larger, but if the projection is made larger, the amount of elastic deformation in the insertion process increases, so the load required for fitting increases.

Therefore, there is a multi-stage insertion joint in which two or more stages of projections are provided (see FIGS. 11 and 12 of Patent Document 1) to improve resistance to load without enlarging the projections. By providing the protrusions and the engaging portions corresponding to the protrusions in multiple stages, the load can be resisted by the plurality of protrusions, so that the resistance force as a whole is improved without enlarging the individual protrusions. be able to.

Japanese Patent No. 4600407

However, when one of the inner joint pipe and the outer joint pipe is provided with multiple steps of protrusions, the other is provided with multiple steps of recesses serving as engaging portions. mesh with each other and get caught, which may deteriorate workability. Such an example will be specifically described with reference to FIGS. 5A, 5B, and 6. FIG.

5A and 5B are schematic diagrams showing the process of inserting a conventional multi-step insertion joint 27, showing cross-sectional views of a portion corresponding to the AA cross section of FIG. 1 of Patent Document 1. FIG. 5A and 5B, the inner joint pipe 3 is attached to the lower end of the steel pipe 7 on the upper side, and the outer joint pipe 5 is attached to the upper end of the steel pipe 7 on the lower side. The inner joint pipe 3 is provided with a divided cylindrical portion 11 composed of a plurality of divided pieces 9 divided in the circumferential direction. It is stepped. Further, the outer joint pipe 5 is provided with a cylindrical portion 17, and the inner peripheral surface of the cylindrical portion 17 is provided with two steps of concave portions 19 that engage with the convex portions 13 in the axial direction. In this description, the protrusion 13 and the recess 19 that engage at the same position in the axial direction when the joint is fitted are regarded as one "step", and are counted as the first step and the second step from the bottom in the drawing.

Below, of the two-stage projections 13, the projection 13 on the lower side (on the distal end side of the inner joint pipe) is the first projection 131, and the projection 13 on the upper side (on the proximal end side of the inner joint pipe) is the second stage. It is assumed that the convex portion 132 is an eye. Similarly, of the two-stage recessed portions 19, the recessed portion 19 on the lower side (base end side of the outer joint pipe) is the first recessed portion 191, and the recessed portion 19 on the upper side (the distal end side of the outer joint pipe) is the recessed portion 192. and In addition, in the joint fitting state, the engaging portion 23 is formed by combining the convex portion 13 and the concave portion 19 in the engaged state.

In the conventional multi-stage insertion joint 27 configured as described above, when the inner joint pipe 3 is inserted into the outer joint pipe 5 while the steel pipe 7 on the lower side is restrained, the first-stage convex portion 131 of the inner joint pipe 3 is inserted. contacts the inner surface of the cylindrical portion 17 of the outer joint pipe 5, the split piece 9 of the inner joint pipe 3 receives a horizontal force indicated by the white arrow in FIG. 5A and is elastically deformed radially inward. The divided cylindrical portion 11 is reduced in diameter by elastically deforming the plurality of divided pieces 9 radially inward.

In this state, the split piece 9 is further inserted, and as shown in FIG. There is a resilience that tries to recover. When the diameter of the divided cylindrical portion 11 expands due to the restoring force, the outer peripheral portion of the first-stage convex portion 131 meshes with the second-stage concave portion 192 and is caught.

If the engagement is shallow, it may be possible to eliminate the engagement by applying a large pushing load, but if the engagement is deep, it will be difficult to continue construction. In this case, unless the diameter of the divided cylindrical portion 11 is reduced again using an auxiliary tool, the inner joint pipe 3 cannot be inserted or pulled out, which requires a great deal of labor.

As described above, if the convex portion 13 and the concave portion 19, which are not to be engaged, are engaged with each other during insertion, the installation load may be greatly increased, degrading workability, or causing installation troubles such as inability to fit. there's a possibility that.

5A and 5B are examples in which the

pipe axes

3a, 5a of the inner joint pipe 3 and the outer joint pipe 5 are aligned, but the

pipe axes

3a, 5a of the inner joint pipe 3 and the outer joint pipe 5 If 5a is misaligned, the above problems are more likely to occur. Such an example will be described with reference to FIG.

FIG. 6 shows a conventional multi-stage insertion joint 27 similar to FIGS. 5A and 5B, in which the inner joint pipe 3 is connected to the outer joint in a state where the pipe axis 3a of the inner joint pipe 3 and the pipe axis 5a of the outer joint pipe 5 are deviated from each other. It is a figure in the middle of insertion at the time of inserting into the pipe|tube 5. FIG. In the case of construction under poor connection environment (site, large diameter, long length, etc.), it is difficult to control the verticality of the inner joint pipe 3 and the outer joint pipe 5, and as shown in FIG. Construction may be performed in a state where the pipe axis 3a of the pipe 3 and the pipe axis 5a of the outer joint pipe 5 are misaligned.

In this case, as shown in FIG. 6, the first-stage protrusion 131 is likely to collide with the lower side wall of the second-stage recess 192, so the above-described problem of defective construction is more likely to occur.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems. An object of the present invention is to provide an attached steel pipe, a structure, a construction method for the structure, and a design method and a manufacturing method for a multi-step insertion joint.

(1) A multi-stage insertion joint according to the present invention comprises a cylindrical inner joint pipe and an outer joint pipe respectively attached to ends of steel pipes to be joined, and either the inner joint pipe or the outer joint pipe has a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and a convex portion that is provided in multiple stages in the axial direction on the plurality of divided pieces and protrudes in the radial direction, and the inner joint The other of the pipe and the outer joint pipe has an undivided cylindrical portion and recesses that are provided in the cylindrical portion in multiple stages in the axial direction and engage with the convex portions, and the divided cylindrical portion is arranged radially. The steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the inner joint pipe into the outer joint pipe to engage the convex portion and the concave portion, and the multi-step convex portion is a convex portion on the tip side The axial width of the multi-stage recess gradually decreases from the recess on the proximal end to the recess on the distal end. The directional width is greater than or equal to the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted.

(2) Further, the multi-stage insertion joint according to the present invention includes an inner joint pipe and an outer joint pipe of cylindrical bodies respectively attached to ends of steel pipes to be joined, and either the inner joint pipe or the outer joint pipe One of the inner joint pipe and the outer joint pipe has a divided cylindrical portion composed of a plurality of divided pieces divided in the circumferential direction, and recesses provided in the plurality of divided pieces in the axial direction in multiple stages. The other of the joint pipes has an undivided cylindrical portion and projections that are provided on the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction to engage with the recesses. The steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the inner joint pipe into the outer joint pipe to engage the convex portion and the concave portion, and the multi-step convex portion is a convex portion on the tip side The axial width of the multi-stage recess gradually decreases from the recess on the proximal end to the recess on the distal end. The directional width is greater than or equal to the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted.

(3) In addition, in the above (1) or (2), the axial clearance formed by the engaging projections and recesses is the same for all the engaging portions when the joint is fitted. is.

(4) In addition, in any one of the above (1) to (3), the protrusion height of the multistage protrusion is set to be equal to or less than the protrusion height of the protrusion closest to the distal end side, and At least one of the multi-stage projections is set lower in projection height than the projection on the tip end side.

(5) In the device described in (4) above, the multi-stage convex portion has a protrusion height that gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side.

(6) Further, a steel pipe with a joint according to the present invention includes the inner joint pipe and/or the outer joint pipe in the multi-step insertion joint according to any one of (1) to (5) above. Be prepared.

(7) Further, a structure according to the present invention comprises a plurality of steel pipes connected by the multi-step insertion joint according to any one of (1) to (5) above.

(8) Further, a structure construction method according to the present invention is the structure construction method according to (7) above, wherein the steel pipe having the outer joint pipe attached to its end, and the inner joint pipe While restraining the axial position of one of the steel pipes attached to the ends, the axial position of the other steel pipe is aligned with the one steel pipe and inserted and fitted.

(9) Further, the method for designing a multi-stage insertion joint according to the present invention includes an inner joint pipe and an outer joint pipe of cylindrical bodies respectively attached to ends of steel pipes to be joined, wherein the inner joint pipe or the outer joint pipe Either one of the pipes has a divided cylindrical portion composed of a plurality of divided pieces divided in a circumferential direction, and a convex portion provided in multiple stages in the axial direction on the plurality of divided pieces and protruding in the radial direction. and the other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and concave portions provided in the cylindrical portion in multiple stages in the axial direction and engaged with the convex portions, and the divided A method for designing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the cylindrical portion in the radial direction to engage the convex portion and the concave portion, The multi-stage convex portion is set so that the axial width gradually decreases from the distal-side convex portion to the proximal-side convex portion. The width is set to gradually decrease, and the axial width of each protrusion is set to be greater than or equal to the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted. .

(10) In addition, the cylindrical inner joint pipe and the outer joint pipe are respectively attached to the ends of the steel pipes to be joined, and either the inner joint pipe or the outer joint pipe is divided in the circumferential direction. It has a divided cylindrical portion composed of a plurality of divided pieces, and recesses provided in the plurality of divided pieces in multiple stages in the axial direction, and the other of the inner joint pipe and the outer joint pipe is not divided. It has a cylindrical portion and convex portions that are provided in the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction so as to engage with the concave portions. A method for designing a multi-stage insertion joint that joins steel pipes by inserting into an outer joint pipe and engaging the projection and the recess, wherein the multi-stage projection extends from the projection on the distal end side to the proximal end. The axial width of each convex portion is set to gradually decrease, and the multi-stage concave portion is set so that the axial width gradually decreases from the concave portion on the proximal end side to the concave portion on the distal end side, and the axis of each convex portion The width in the direction is set to be equal to or greater than the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted.

(11) Further, in the joint described in (9) or (10), the axial clearance formed by the engaging projections and recesses is the same for all the engaging portions when the joint is fitted. In addition, the axial width of each convex portion and each concave portion is set.

(12) Further, a method for manufacturing a multi-stage insertion joint according to the present invention includes an inner joint pipe and an outer joint pipe of cylindrical bodies respectively attached to ends of steel pipes to be joined, and Either one of the pipes has a divided cylindrical portion composed of a plurality of divided pieces divided in a circumferential direction, and a convex portion provided in multiple stages in the axial direction on the plurality of divided pieces and protruding in the radial direction. and the other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and concave portions provided in the cylindrical portion in multiple stages in the axial direction and engaged with the convex portions, and the divided A method for manufacturing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while flexing the cylindrical portion in the radial direction to engage the convex portion and the concave portion, The multi-stage convex portion is formed so that the axial width gradually decreases from the distal-side convex portion to the proximal-side convex portion. The width of each convex portion is formed so as to gradually decrease, and the axial width of each convex portion is formed so as to be larger than the axial width of the concave portion located on the tip side of the concave portion that engages when the joint is fitted. .

(13) In addition, a cylindrical inner joint pipe and an outer joint pipe are attached to the ends of the steel pipes to be joined, respectively, and either the inner joint pipe or the outer joint pipe is divided in the circumferential direction. It has a divided cylindrical portion composed of a plurality of divided pieces, and recesses provided in the plurality of divided pieces in multiple stages in the axial direction, and the other of the inner joint pipe and the outer joint pipe is not divided. It has a cylindrical portion and convex portions that are provided in the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction so as to engage with the concave portions. A method for manufacturing a multi-stage insertion joint in which the steel pipes are joined by inserting them into the outer joint pipe and engaging the projections and the recesses, wherein the multi-stage projections extend from the projections on the distal end side to the proximal end side. The axial width of the multi-stage recesses is formed so that the axial width gradually decreases from the recess on the base end side to the recess on the tip end side, and the axis of each protrusion The directional width is formed so as to be equal to or greater than the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted.

(14) In addition, in the above (12) or (13), when the joint is fitted, the axial clearance formed by the engaging projections and recesses is the same for all the engaging portions. Then, each convex portion and each concave portion are formed.

In the present invention, the axial width of the multi-stage projection gradually decreases from the distal-side projection to the proximal-side projection, and the multi-stage recess has an axial width from the proximal-side recess to the distal-side recess. The directional width gradually decreases, and the axial width of each protrusion is larger than the axial width of the recess located on the distal end side of the recess that engages when the joint is fitted. It is possible to prevent the non-objective protrusions and recesses from engaging with each other. As a result, it is possible to suppress catching during joining of steel pipes, greatly increase the work load, reduce workability, and reduce the occurrence of construction troubles such as impossibility of fitting, thereby improving workability.

FIG. 1 is an explanatory view of the multi-step insertion joint according to Embodiment 1 of the present invention, and is a cross-sectional view of part of the multi-step insertion joint in a fitted state. FIG. 2 is a view showing a state in the middle of fitting the multi-stage insertion joint shown in FIG. 1 (in the case of no shaft misalignment). FIG. 3 is a diagram showing a state in the middle of fitting the multi-stage insertion joint shown in FIG. 1 (in the case of shaft misalignment). FIG. 4 is an explanatory diagram of a multi-step insertion joint according to Embodiment 2 of the present invention, and is a cross-sectional view of part of the multi-step insertion joint in the middle of fitting. FIG. 5A is a diagram for explaining a problem of a conventional multi-stage insertion joint (in the case of no shaft misalignment). FIG. 5B is a diagram for explaining a problem with a conventional multi-stage insertion joint (in the case of no shaft misalignment). FIG. 6 is a diagram for explaining a problem with a conventional multi-stage insertion joint (in the case of shaft misalignment).

[Embodiment 1]
The overall structure of the multi-stage insertion joint according to the present embodiment is substantially the same as that shown in FIG. 12 of Patent Document 1, so the illustration is omitted, and only a cross-sectional view of a part of the multi-stage insertion joint is shown in FIG. FIG. 1 shows a cross section of a portion corresponding to the AA cross section of FIG. 1 of Patent Document 1. As shown in FIG. 5A, 5B, and 6 describing the conventional multi-stage insertion joint 27 are denoted by the same reference numerals.

A multi-stage insertion joint 1 of the present embodiment includes an inner joint pipe 3 and an outer joint pipe 5 attached to the ends of steel pipes to be joined, respectively. An example in which an outer joint pipe 5 is attached to the upper ends of the inner joint pipe 3 and the lower steel pipe 7 is shown. As shown in FIG. 1, the upper and lower steel pipes 7 are joined by inserting the inner joint pipe 3 into the outer joint pipe 5 and fitting the inner joint pipe 3 and the outer joint pipe 5 together. The inner joint pipe 3 and the outer joint pipe 5 will be described in detail below.

<Inner joint pipe>
The inner joint pipe 3 is formed of a substantially cylindrical body and has a divided cylindrical portion 11 composed of a plurality of divided pieces 9 divided in the circumferential direction. A convex portion 13 protruding radially outward is provided in two steps in the axial direction on the outer peripheral surface of the divided cylindrical portion 11 over the entire circumference. 5A, 5B, and 6, the convex portion 13 on the lower side (the tip side of the inner joint pipe 3) is the first convex portion 131, and the convex portion 13 on the upper side (the inner joint pipe) 3) is referred to as a second stage convex portion 132. As shown in FIG. Although FIG. 1 shows the cross section of one split piece 9, the cross sections of the other split pieces 9 are the same as in FIG. A bolt hole 15 for bolting to the outer joint pipe 5 is provided on the tip side of the first-stage convex portion 131 .

<Outer joint pipe>
The outer joint pipe 5 is made of a cylindrical body and has an undivided cylindrical portion 17 . The inner peripheral surface of the cylindrical portion 17 is provided with two-stage recesses 19 that are recessed radially outward along the entire circumference. Regarding the two-stage recesses 19, similarly to the protrusions 13 of the inner joint pipe, the recesses 19 on the lower side (the proximal side of the outer joint pipe 5) are the first-stage recesses 191, and the recesses 19 on the upper side (the distal end side of the outer joint pipe 5) ) is referred to as a second stage recess 192 . As shown in FIG. 1 , in the joint fitted state, the first stage recess 191 engages with the first stage projection 131 , and the second stage recess 192 engages with the second stage projection 132 . A bolt hole 21 for inserting a bolt is provided at a position facing the bolt hole 15 of the inner joint pipe 3 on the proximal end side of the first stage concave portion 191 .

Here, as shown in the enlarged view of FIG. 1, the axial width of the first-stage convex portion 131 is T1, the radially outward protrusion height is H1, the axial width of the first-stage concave portion 191 is K1, Let L1 be the depth of the recess radially outward. Similarly, the axial width of the second-stage projection 132 is T2, the radially outward projection height is H2, the axial width of the second-stage recessed portion 192 is K2, and the radially outward depth of the recess is L2. (enlarged view omitted). The above T1 and T2 are the widths in the axial direction of the apex (tip) of the projection 13 . K1 and K2 are the widths in the axial direction of the opening of the recess.

As described above, the axial widths T1 and T2 are the axial widths at the tops of the first stepped protrusion 131 and the second stepped protrusion 132, and the roots of the first stepped protrusion 131 and the second stepped protrusion 132. The axial width of the portion may be set based on the shear resistance required for the entire protrusion 13 . In general, the shear strength of the convex portion 13 can be set with a sufficient margin, so even if the shear strength of the convex portion 13 varies slightly by changing the axial width of the top portion of the convex portion 13, the impact on the strength of the joint as a whole is small.

The recess depth L1 of the first stage recess 191 is larger than the projection height H1 of the first stage projection 131 so that the first stage projection 131 and the first stage recess 191 can be engaged (H1 <L1). Similarly, the recess depth L2 of the second step recess 192 is larger than the protrusion height H2 of the second step protrusion 132 (H2<L2).

In the two-step convex portion 13 provided on the divided cylindrical portion 11 of the inner joint pipe 3, the axial width T2 of the proximal-side convex portion 13 (second-step convex portion 132) is the tip-side convex portion. It is smaller than the axial width T1 of the portion 13 (first stage convex portion 131) (T2<T1). Further, in the two-stage recess 19 provided in the cylindrical portion 17 of the outer joint pipe 5, the axial width K2 of the recess 19 (second-stage recess 192) on the distal end side is greater than the width K2 of the recess 19 (first-stage recess) on the proximal end side. It is smaller than the axial width K1 of the eye recess 191) (K2<K1). Furthermore, the axial width T1 of the first stage protrusion 131 is the axial width of the recess 19 (second stage recess 192) located on the distal end side of the recess 19 (first stage recess 191) engaged when the joint is fitted. It has a size equal to or larger than K2 (K2≦T1). From the above, the multi-stage insertion joint 1 of this embodiment satisfies the following relational expressions (1) to (3).
H1<L1 (1)
H2<L2 (2)
T2<K2≤T1<K1 (3)

As described above, the split cylindrical portion 11 of the inner joint pipe 3 is composed of a plurality of split pieces 9 arranged in the circumferential direction, and the axial widths T1 and T2 of the two-stage convex portion 13 and the projection It is assumed that all the divided pieces 9 have the same heights H1 and H2. The two-stage recess 19 provided in the cylindrical portion 17 of the outer joint pipe 5 is provided continuously in the circumferential direction on the inner peripheral surface of the cylindrical portion 17, and has axial widths K1, K2 and recesses. It is assumed that the depths L1 and L2 are constant over the entire circumference.

Also, the axial gap δ of the first-stage engaging portion 23 shown in the enlarged view of FIG. ) is the same as the axial clearance in the engaging portion 23 of the second stage. As described above, since the axial gap formed by the convex portion 13 and the concave portion 19 that engage with each other in the joint fitted state is the same for all of the engaging portions 23, load transmission is performed appropriately. This is suitable when the joint 1 is used as part of a structure.

The effects of the multi-stage insertion joint 1 of the present embodiment configured as described above will be specifically described below. In the conventional multi-stage insertion joint 27, as described with reference to FIGS. 5A and 5B, when the first-stage projection 131 reaches the second-stage recess 192 during fitting, the tip of the first-stage projection 131 entered the second step recess 192 and got caught.

In this respect, in the multi-stage insertion joint 1 of the present embodiment, since the axial width T1 of the first-stage convex portion 131 is greater than or equal to the axial width K2 of the second-stage concave portion 192 (K2≤T1), the above-mentioned No such problem occurs. Specifically, as shown in FIG. 2 , even if the first-stage projection 131 reaches the second-stage recess 192 , a part of the first-stage projection 131 always contacts the inner peripheral surface of the cylindrical portion 17 . remain in contact. Therefore, the first-stage convex portion 131 can pass over the second-stage concave portion 192 while maintaining the radially inward elastic deformation of the split piece 9, and is less likely to be caught. Even when K2=T1, the above-mentioned problem does not occur because the penetration is shallow due to friction or the like and the catching is small. In this respect, it is more preferable that the axial width T1 of each convex portion is larger than the axial width K2 of the concave portion located on the distal end side of the concave portion that is engaged when the joint is fitted, because it is more difficult to get caught.

In addition, as described with reference to FIG. 6, the conventional multi-stage insertion joint 27 is especially caught when the pipe axis 3a of the inner joint pipe 3 and the pipe axis 5a of the outer joint pipe 5 are not aligned with each other. was In this respect, the present embodiment has the effect of suppressing catching even when construction is performed in the state of axial deviation as described above. This will be described with reference to FIG.

FIG. 3 shows the multi-stage insertion joint 1 of the present embodiment, in which the inner joint pipe 3 is inserted into the outer joint pipe 5 with the pipe axis 3a of the inner joint pipe 3 and the pipe axis 5a of the outer joint pipe 5 deviated from each other. It is a figure in the middle of insertion of a case. As shown in the enlarged view of FIG. 3 , if the outer joint pipe 5 is tilted, the first stage protrusion 131 may collide with the lower side wall of the second stage recess 192 . In this case, in the conventional example, as shown in the enlarged view of FIG. 6, the entire tip portion of the first stage protrusion 131 enters the second stage recess 192 due to the restoring force that tries to recover the elastic deformation, so that the hook is deep and Construction may not continue. In addition, in the state shown in FIG. 6, even if the inner joint pipe 3 is to be pulled out in order to redo the work, the first-step convex portion 131 is caught in the upper side wall of the second-step concave portion 192, so the diameter of the divided cylindrical portion 11 is reduced. It is necessary to use an assistive device to

In this respect, in the multi-stage insertion joint 1 of the present embodiment, since the axial width T1 of the first-stage convex portion 131 is greater than or equal to the axial width K2 of the second-stage concave portion 192 (K2≤T1), the above-mentioned No such problem occurs. Specifically, as shown in the enlarged view of FIG. 3, even if the first-stage protrusion 131 collides with the lower side wall of the second-stage recess 192, the tip of the first-stage protrusion 131 as a whole is 2 It does not get into the step recess 192 . Therefore, the hooking is shallow, and if the insertion load is slightly increased, the hooking can be easily released and the construction can be continued. Even when K2=T1, the above-mentioned problem does not occur because the penetration is shallow due to friction or the like and the catching is small. In this respect, it is more preferable that the axial width T1 of each convex portion is larger than the axial width K2 of the concave portion located on the distal end side of the concave portion that is engaged when the joint is fitted, because it is more difficult to get caught.

In addition, even if the inner joint pipe 3 is to be pulled out for redoing construction, unlike the conventional example, the first stage projection 131 does not get caught on the upper side wall of the second stage recess 192. is also easy.

Although the above is an example in which the outer joint pipe 5 attached to the lower steel pipe 7 is inclined, the same effect can be obtained when the inner joint pipe 3 attached to the upper steel pipe 7 is inclined. Play.

As described above, according to the present embodiment, the axial width T2 of the second stage protrusion 132 is smaller than the axial width T1 of the first stage protrusion 131 (T2<T1). The axial width K2 of the second step recess 192 is smaller than the axial width K1 of the step recess 191 (K2<K1). As a result, the axial width T1 of the first-stage protrusion 131 is the axial width of the recess 19 (second-stage recess 192) on the tip side of the recess 19 (first-stage recess 191) that engages when the joint is fitted. K1 or more (K1≤T1). Therefore, it is possible to prevent the convex portion 13 and the concave portion 19, which are not to be engaged, from meshing with each other during insertion. As a result, even if the connection environment is poor and looseness is likely to occur, it is possible to reduce the occurrence of construction troubles such as a large increase in the installation load, which deteriorates workability, or makes it impossible to fit. improve sexuality.

Although the first embodiment described above has two stages of the engaging portion 23, the number of stages of the engaging portion 23 may be any number within the workable range. Further, in the case of three or more steps, the width in the axial direction gradually decreases from the protrusion 13 on the distal end side to the protrusion 13 on the proximal end side. Correspondingly, the width in the axial direction gradually decreases from the concave portion 19 on the proximal end side to the concave portion 19 on the distal end side. The axial width of each convex portion 13 is made larger than the axial width of the concave portion 19 located on the distal end side of the concave portion 19 that is engaged when the joint is fitted. In the conventional multi-stage insertion joint 27, as the number of steps of the engaging portion 23 increases, the risk of being caught during insertion increases. It is possible to suppress catching regardless of the number of steps. Therefore, the present invention is particularly suitable for multi-stage insertion joints having a large number of stages of engaging portions.

[Embodiment 2]
Although the first embodiment described above is an example in which the projection heights of the projections 13 are all the same (H1=H2), in the present embodiment, the projection height H1 of the first-stage projections 131 is two steps. An example in which the projection height H2 of the eye projection 132 is increased will be described. FIG. 4 shows the multi-stage insertion joint of this embodiment, and the same reference numerals are given to the same or corresponding parts as in FIGS.

In the multi-stage insertion joint 25 of the present embodiment, as shown in FIG. 4, the projection height H1 of the first-stage projection 131 is larger than the projection height H2 of the second-stage projection 132 (H2< H1). Further, as the projection height H1 of the first-stage convex portion 131 is increased, the recess depth L1 of the first-stage recessed portion 191 is also increased so that H1<L1. Since the multi-stage insertion joint 1 of the first embodiment is the same as the multi-stage insertion joint 1 of the first embodiment except for the points described above, the multi-stage insertion joint 25 of the present embodiment satisfies the relational expressions (1) to (3) described in the first embodiment. In addition, it satisfies the following relational expression (4).
H2<H1 (4)

The projection height H1 of the first stage projection 131 is greater than the projection height H2 of the second stage projection 132 . In other words, the protrusion height H2 of the second step protrusion 132 is smaller than the protrusion height H1 of the first step protrusion 131 . As a result, in the process of inserting the inner joint pipe 3 into the outer joint pipe 5, a gap is generated between the second-stage convex portion 132 and the inner peripheral surface of the cylindrical portion 17 as shown in FIG. Due to this gap, friction does not occur between the second-stage convex portion 132 and the inner peripheral surface of the cylindrical portion 17, so that the construction resistance when inserting the inner joint pipe 3 into the outer joint pipe 5 can be reduced.

Although the second embodiment described above has two stages of the engaging portion, the number of stages of the engaging portion 23 may be any number within the workable range. For example, when there are three stages of engaging portions, the second-stage protrusion crosses over the third-stage recess before engaging with the second-stage recess, as shown in FIG. If the portion does not abut on the inner peripheral surface of the cylindrical portion 17, the second step protrusion is less likely to catch on the third step recess.

When three or more multi-stage convex portions 13 are provided, the projection height of the multi-stage convex portions 13 is set to be equal to or less than the projection height of the convex portion 13 closest to the distal end side, and one of the multi-stage convex portions 13 At least one of them may be set to have a lower protrusion height than the protruding portion 13 closest to the tip. That is, the protrusions 13 having the same protrusion height as the first-stage protrusion 131 may be arranged every several steps, and in this case, the construction resistance is reduced compared to when the protrusions 13 all have the same protrusion height. be. Further, the protrusion 13 having a lower protrusion height than the first-stage protrusion 131 is less likely to get caught during insertion than the protrusion 13 having the same protrusion height as the first-stage protrusion 131 . However, since the first stage protrusion 131 and the other protrusions 13 having the same projection height as the first stage protrusion 131 also have a larger axial width than the recess 19 that is overcome during insertion, they are less likely to get caught than in the conventional example. .

In addition, since at least one of the multi-stage projections 13 may be set to have a lower projection height than the projection 13 closest to the distal end, for example, the distance from the projection 13 on the distal end to the proximal end is sufficient. The protrusion height may be gradually lowered toward the protrusion 13 .

The upper limit of the height of the projection 13 is determined by checking the thickness of the steel material required for the joint pipe having the corresponding recess 19, and is determined by the bearing force necessary to prevent the projection 13 and recess 19 from coming off and breaking. A lower bound is determined. The height of each convex portion 13 can be changed as long as it is within the range of the upper limit value and the lower limit value described above. It is sufficient if the above is satisfied.

Although the first and second embodiments described above are examples in which the side to be inserted inside (inner joint tube 3) is divided, the present invention is not limited to this, and the side (outer joint tube 3) to be placed on the outside is divided. 5) may be divided. That is, it is composed of an outer joint pipe 5 having a split cylindrical portion 11 with multi-stage projections 13 formed on its inner peripheral surface, and an inner joint pipe 3 having a cylindrical portion 17 with multi-stage recesses 19 formed on its outer peripheral surface. You may Also in this case, the axial width of the multi-stage convex portion 13 gradually decreases from the convex portion 13 on the distal end side to the convex portion 13 on the proximal end side. In addition, the axial width of the multi-stage recessed portion 19 gradually decreases from the recessed portion 19 on the proximal end side to the recessed portion 19 on the distal end side. Further, the axial width of each convex portion 13 is greater than or equal to the axial width of the recessed portion 19 located on the distal end side of the recessed portion 19 engaged when the joint is fitted.

Moreover, the above is an example in which the multi-stage convex portion 13 is formed on the divided side (divided cylindrical portion 11) and the multi-stage concave portion 19 is formed on the non-divided side (cylindrical portion 17). Not limited. That is, the divided cylindrical portion 11 may be provided with the multi-stage concave portion 19 and the cylindrical portion 17 may be provided with the multi-stage convex portion 13 . That is, as shown in FIG. 11 of Patent Document 1, an outer joint pipe 5 having a divided cylindrical portion 11 formed with multistage concave portions 19 and an inner joint pipe having a cylindrical portion 17 formed with multistage convex portions 13. 3. Alternatively, it may be composed of the inner joint pipe 3 having the divided cylindrical portion 11 formed with the multi-stage concave portions 19 and the outer joint pipe 5 having the cylindrical portion 17 formed with the multi-stage convex portions 13 . Also in this case, the axial width of the multi-stage convex portion 13 gradually decreases from the convex portion 13 on the distal end side to the convex portion 13 on the proximal end side. In addition, the axial width of the multi-stage recessed portion 19 gradually decreases from the recessed portion 19 on the proximal end side to the recessed portion 19 on the distal end side. Furthermore, the axial width of each convex portion 13 is greater than or equal to the axial width of the recessed portion 19 located on the distal end side of the recessed portion 19 engaged when the joint is fitted. In any of the above cases, effects similar to those of the first and second embodiments can be exhibited.

In addition, although the first and second embodiments described above show connection by vertical movement, the direction of movement may be the axial direction of the steel pipe, and connection may be made by diagonal piles or horizontal joints.

In addition, if the above-described relational expressions (1) to (3) or, in addition, the relational expression (4) is satisfied (when the engaging portion 23 has two stages), the shape of the convex portion 13 and the concave portion 19 is not particularly limited. Even if the shape is different from those exemplified in the first and second embodiments, the effect can be exhibited.

Further, in the above embodiment, the

multi-stage insertion joints

1 and 25 attached to the ends of the steel pipes 7 have been described, but the inner joint pipe 3 and/or the outer joint pipe 5 of the

multi-stage insertion joints

1 and 25 are A steel pipe with a joint can be manufactured by attaching it to the end of the steel pipe 7 by welding or the like in a factory or the like. That is, the joint-equipped steel pipe may have the inner joint pipe 3 and/or the outer joint pipe 5 of the

multi-step insertion joints

1 and 25 described in the first and second embodiments at both ends or one end.

By connecting multiple steel pipes with joints at construction sites, etc., structures such as steel pipe piles, steel pipe sheet piles, steel pipe sheet pile walls connecting steel pipe sheet piles, steel pipe columns, and steel pipe beams can be formed. That is, these structures include a plurality of steel pipes connected by the

multi-step insertion joints

1 and 25 described in the first and second embodiments.

When constructing these structures, the axial position of either the steel pipe 7 with the outer joint pipe 5 attached to the end or the steel pipe 7 with the inner joint pipe 3 attached to the end is restrained. Then, the axial position of the other steel pipe 7 may be aligned with the one steel pipe 7 and then inserted and fitted.

In addition, although the first and second embodiments relate to the multi-stage insertion joint as an invention of the product, it can be reconfigured as an invention of a design method and an invention of a manufacturing method. become.

<Design method invention 1>
A cylindrical inner joint pipe and an outer joint pipe are attached to the ends of steel pipes to be joined, respectively, and either the inner joint pipe or the outer joint pipe is a plurality of divided pieces divided in the circumferential direction. and radially protruding convex portions provided in multiple stages in the axial direction on the plurality of divided pieces, and the other of the inner joint pipe and the outer joint pipe is divided. and recesses provided in the cylindrical portion in multiple stages in the axial direction and engaged with the protrusions, and the inner joint pipe is moved to the outer joint pipe while the divided cylindrical portions are flexed in the radial direction. A method for designing a multi-stage insertion joint for joining the steel pipes by inserting the joint into a joint to engage the convex portion and the concave portion, wherein the multi-stage convex portion is formed from a convex portion on the distal end side to a convex portion on the proximal end side The axial width of each convex portion is set to gradually decrease from the concave portion on the base end side to the concave portion on the distal end side. A method of designing a multi-step insertion joint, wherein the size is set to be equal to or greater than the axial width of a recess located on the tip side of the recess that engages when the joint is fitted.

<Design method invention 2>
A cylindrical inner joint pipe and an outer joint pipe are attached to the ends of steel pipes to be joined, respectively, and either the inner joint pipe or the outer joint pipe is a plurality of divided pieces divided in the circumferential direction. and recesses provided in multiple stages in the axial direction of the plurality of split pieces, wherein the other of the inner joint pipe and the outer joint pipe is an undivided cylindrical portion; The cylindrical portion has projections that are provided in multiple stages in the axial direction and protrude in the radial direction to engage with the recesses. A method for designing a multi-stage insertion joint for joining the steel pipes by engaging the projection and the recess in the multi-stage projection, wherein the multi-stage projection extends from the projection on the distal end side to the projection on the base end side. The directional width is set to gradually decrease, and the axial width of the multi-stage recess is set to gradually decrease from the recess on the proximal end side to the recess on the distal end side, and the axial width of each protrusion is set to be the same as that of the joint. A method for designing a multi-step insertion joint in which the size is set to be equal to or greater than the axial width of a recess located on the tip side of a recess that engages during fitting.

<Design method invention 3>
In the above design method, the axial width of each projection and each recess is set so that the axial clearance formed by the projection and recess that engage with each other in the joint fitted state is the same for all engaging portions. A method for designing a multi-stage insertion joint according to invention 1 or 2.

<Invention 1 of manufacturing method>
A cylindrical inner joint pipe and an outer joint pipe are attached to the ends of steel pipes to be joined, respectively, and either the inner joint pipe or the outer joint pipe is a plurality of divided pieces divided in the circumferential direction. and radially protruding convex portions provided in multiple stages in the axial direction on the plurality of divided pieces, and the other of the inner joint pipe and the outer joint pipe is divided. and recesses provided in the cylindrical portion in multiple stages in the axial direction and engaged with the protrusions, and the inner joint pipe is moved to the outer joint pipe while the divided cylindrical portions are flexed in the radial direction. A method for manufacturing a multi-stage insertion joint for joining the steel pipes by inserting the joint into the joint to engage the projection and the recess, wherein the multi-stage projection extends from the projection on the distal end side to the projection on the proximal end side The axial width of each convex portion is formed so that the axial width gradually decreases from the concave portion on the base end side to the concave portion on the distal end side. A method for manufacturing a multi-step insertion joint, wherein the width of the recess located on the distal end side of the recess engaged when fitting the joint is equal to or greater than the width of the recess in the axial direction.

<Invention 2 of manufacturing method>
A cylindrical inner joint pipe and an outer joint pipe are attached to the ends of steel pipes to be joined, respectively, and either the inner joint pipe or the outer joint pipe is a plurality of divided pieces divided in the circumferential direction. and recesses provided in multiple stages in the axial direction of the plurality of split pieces, wherein the other of the inner joint pipe and the outer joint pipe is an undivided cylindrical portion; The cylindrical portion has projections that are provided in multiple stages in the axial direction and protrude in the radial direction to engage with the recesses. A method for manufacturing a multi-stage insertion joint for joining the steel pipes by engaging the convex portion and the concave portion in the step, wherein the multi-step convex portion extends from the convex portion on the distal end side to the convex portion on the proximal end side. The directional width is formed to gradually decrease, and the multistage recesses are formed so that the axial width gradually decreases from the recess on the proximal end side to the recess on the distal end side, and the axial width of each protrusion is equal to the width of the joint. A method for manufacturing a multi-stage insertion joint formed so as to have a size equal to or greater than the axial width of a recess located on the distal end side of a recess that engages at the time of fitting.

<Invention 3 of manufacturing method>
Invention 1 or 2 of the above manufacturing method, wherein each projection and each recess are formed such that the axial gap formed by the projection and recess that engage with each other in the joint fitted state is the same for all engaging portions. A method for manufacturing the multi-stage insertion joint according to 1.

The present invention is suitable for application to joining steel pipes.

1 Multi-stage insertion joint (Embodiment 1)
3 inner joint pipe 3a pipe shaft 5 outer joint pipe 5a pipe shaft 7 steel pipe 9 split piece 11 split cylindrical portion 13 convex portion 131 first step convex portion 132 second step convex portion 15 bolt hole (inner joint pipe)
17 cylindrical portion 19 recessed portion 191 first stage recessed portion 192 second stage recessed portion 21 bolt hole (outer joint pipe)
23 Engagement part 25 Multi-stage insertion joint (Embodiment 2)
27 Multi-stage insertion joint (conventional example)

Claims

Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe includes a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and a divided cylindrical portion formed by a plurality of divided pieces divided in the axial direction in multiple stages in the axial direction. and a convex portion protruding to
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and recesses provided in the cylindrical portion in multiple stages in the axial direction and engaged with the protrusions,
A multi-stage insertion joint that joins the steel pipes by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion,
The axial width of the multistage convex portion gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The axial width of the multi-stage recessed portion gradually decreases from the recessed portion on the proximal end side to the recessed portion on the distal end side,
The multi-step insertion joint, wherein the axial width of each projection is greater than or equal to the axial width of the recess located on the distal end side of the recess engaged when the joint is fitted.
Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe has a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and recesses provided in multiple stages in the axial direction in the plurality of divided pieces. has
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and convex portions that are provided in the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction to engage with the concave portions,
A multi-stage insertion joint that joins the steel pipes by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion,
The axial width of the multistage convex portion gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The axial width of the multi-stage recessed portion gradually decreases from the recessed portion on the proximal end side to the recessed portion on the distal end side,
The multi-step insertion joint, wherein the axial width of each projection is greater than or equal to the axial width of the recess located on the distal end side of the recess engaged when the joint is fitted.
3. The multi-stage insertion joint according to claim 1, wherein, in the joint fitted state, the axial clearances formed by the engaging projections and recesses are the same in all the engaging portions.
The projection height of the multistage projection is set to be equal to or less than the projection height of the projection on the most tip side, and at least one of the multistage projections has a projection height greater than the projection on the tip end side. 4. The multi-stage insertion joint according to any one of claims 1 to 3, which is set low.
5. The multistage insertion joint according to claim 4, wherein the projection height of the multistage projection gradually decreases from the projection on the distal end side to the projection on the base end side.
A steel pipe with a joint, wherein the inner joint pipe and/or the outer joint pipe in the multi-stage insertion joint according to any one of claims 1 to 5 is provided at both ends or at one end.
A structure comprising a plurality of steel pipes connected by the multi-step insertion joint according to any one of claims 1 to 5.
A construction method for a structure according to claim 7,
While restraining the axial position of one of the steel pipe with the outer joint pipe attached to the end and the steel pipe with the inner joint pipe attached to the end, the other steel pipe is moved to the axial position of the steel pipe. A method of constructing a structure that is aligned and inserted into steel pipes.
Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe includes a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and a divided cylindrical portion formed by a plurality of divided pieces divided in the axial direction in multiple stages in the axial direction. and a convex portion protruding to
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and recesses provided in the cylindrical portion in multiple stages in the axial direction and engaged with the protrusions,
A method for designing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion. ,
The multistage convex portion is set so that the axial width gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The multistage recess is set so that the axial width gradually decreases from the recess on the proximal end side to the recess on the distal end side,
A method for designing a multi-stage insertion joint, wherein the axial width of each protrusion is set to be greater than or equal to the axial width of a recess located on the tip end side of a recess that engages when the joint is fitted.
Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe has a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and recesses provided in multiple stages in the axial direction in the plurality of divided pieces. has
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and convex portions that are provided in the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction to engage with the concave portions,
A method for designing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion. ,
The multistage convex portion is set so that the axial width gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The multistage recess is set so that the axial width gradually decreases from the recess on the proximal end side to the recess on the distal end side,
A method for designing a multi-stage insertion joint, wherein the axial width of each protrusion is set to be greater than or equal to the axial width of a recess located on the tip end side of a recess that engages when the joint is fitted.
10. The axial width of each projection and each recess is set so that the axial clearance formed by the projection and recess that engage with each other in the joint fitted state is the same for all engaging portions. 11. The method for designing a multi-step insertion joint according to 10.
Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe includes a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and a divided cylindrical portion formed by a plurality of divided pieces divided in the axial direction in multiple stages in the axial direction. and a convex portion protruding to
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and recesses provided in the cylindrical portion in multiple stages in the axial direction and engaged with the protrusions,
A method for manufacturing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion. ,
The multistage convex portion is formed so that the axial width gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The multistage recess is formed so that the axial width gradually decreases from the recess on the base end side to the recess on the tip end side,
A method for manufacturing a multi-stage insertion joint, wherein the axial width of each projection is greater than or equal to the axial width of a recess located on the tip end side of the recess that engages when the joint is fitted.
Equipped with a cylindrical inner joint pipe and an outer joint pipe respectively attached to the ends of the steel pipes to be joined,
Either one of the inner joint pipe and the outer joint pipe has a divided cylindrical portion configured by a plurality of divided pieces divided in the circumferential direction, and recesses provided in multiple stages in the axial direction in the plurality of divided pieces. has
The other of the inner joint pipe and the outer joint pipe has an undivided cylindrical portion and convex portions that are provided in the cylindrical portion in multiple stages in the axial direction and protrude in the radial direction to engage with the concave portions,
A method for manufacturing a multi-stage insertion joint in which the steel pipes are joined by inserting the inner joint pipe into the outer joint pipe while bending the divided cylindrical portion in the radial direction and engaging the convex portion and the concave portion. ,
The multistage convex portion is formed so that the axial width gradually decreases from the convex portion on the distal end side to the convex portion on the proximal end side,
The multistage recess is formed so that the axial width gradually decreases from the recess on the base end side to the recess on the tip end side,
A method for manufacturing a multi-stage insertion joint, wherein the axial width of each projection is greater than or equal to the axial width of a recess located on the tip end side of the recess that engages when the joint is fitted.
14. The projections and recesses according to claim 12 or 13, wherein the projections and recesses are formed such that the axial clearances formed by the projections and recesses that engage with each other are the same for all engaging portions in a joint fitted state. A method for manufacturing a multi-stage insertion joint.