Mechanical joint, joining method for mechanical joint, steel pipe, structure, construction method for structure, design method for mechanical joint, and manufacturing method for mechanical joint

Abstract

To provide: a mechanical joint that does not require rotation or application of a large load for joining, can transmit a torsional load without additionally incurring excessive costs, and does not come off or reduce the strength of the joint; a joining method for the mechanical joint; a steel pipe fitted with the mechanical joint; a structure having the steel pipe as a constituent element; a construction method for the structure; a design method for the mechanical joint; and a manufacturing method for the mechanical joint.SOLUTION: A mechanical joint 1 of the present invention comprises one or more stages of annular grooves 15 formed on an outer peripheral surface of a male joint 3 and an inner peripheral surface of a female joint 5 so as to face each other when insertion is complete, a C-shaped ring member 17 that can be positioned within the annular groove 15 so as to straddle the male joint 3 side and the female joint 5 side, anti-rotation pin insertion holes 13M, 13F provided in the male joint 3 and the female joint 5, and an anti-rotation pin 11 that passes through the anti-rotation pin insertion hole 13F and a C-shaped cutout portion 19 of the female joint 5 and reaches the anti-rotation pin insertion hole 13M of the male joint 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mechanical joint applied to steel pipe piles and steel pipe sheet piles, a joining method for the mechanical joint, a steel pipe fitted with the mechanical joint, a structure including the steel pipe as a component, a construction method for the structure, a design method for the mechanical joint, and a manufacturing method for the mechanical joint. [Background technology]

[0002] Joining of steel pipe piles and steel pipe sheet piles has traditionally been done mainly by on-site welding, but in recent years, due to factors such as a decrease in skilled workers, shortened construction periods, and quality control, joining using mechanical joints has become more common. In the case of steel pipe piles and steel pipe sheet piles, the tubular joint members are generally manufactured separately from the steel pipes, and then the joint members are welded to the ends of the steel pipes to be joined, and then the joint members are joined together.

[0003] The joint must be designed to be able to transmit the compressive, tensile, shear, and torsional loads that act on the pile during construction and operation. Compressive loads can be easily transmitted by bringing the end faces of the joint members into surface contact, and shear loads can be easily transmitted by inserting a male pipe into a female pipe to create a double-pipe structure. However, tensile and torsional loads cannot be transmitted by simple insertion and surface contact, and require structural modification.

[0004] For example, Patent Document 1 (JP Patent Publication No. 10-311028A) discloses a structure in which a joint component has a multiple-start thread shape, and the threads of the male and female joints mesh together through a rotary joint, allowing for the transmission of tensile loads. While forward torsional loads can be transmitted by fully tightening the screws, reverse torsional loads cannot. Therefore, a bolt is placed on the outer periphery of the joint so that it straddles the male and female joints, allowing the reverse torsional load to be transmitted by the shear of the bolt.

[0005] Furthermore, Patent Document 2 (JP 2004-36329 A) discloses a coupling structure in which either the male or female coupling has a plurality of circumferential slits in the pipe axis direction, and the coupling members separated by the slits are machined to be able to elastically deform in the radial direction, and the separated coupling members have convex portions and the other member has concave portions that engage with the convex portions when mating is complete.The disclosed structure is such that when a compressive load is applied due to its own weight or the like when inserting the coupling, the separated coupling members bend in the radial direction, and when they return to their original shape after insertion is complete, the convex portions and concave portions engage with each other, allowing the transmission of a tensile load. In addition, in this structure, as in Patent Document 1, bolts are arranged on the outer peripheral surface, making it possible to transmit torsional loads.

[0006] As another method, Patent Document 3 (JP Patent Publication No. 11-36285) discloses a structure in which grooves are provided in both the male and female joints so that their axial positions are aligned when mating is complete, and a ring-shaped member with a changeable diameter that fits into the groove is stored in either the male or female joint, and when mating is complete, the ring-shaped member is moved radially and positioned so that it straddles the male and female joints, thereby allowing tensile loads to be transmitted. This structure also cannot transmit torsional loads, so it is necessary to either place a bolt as in Patent Documents 1 and 2, or to place a separate anti-rotation mechanism as in Patent Document 4 (Japanese Patent Laid-Open No. 2000-319874). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 10-311028 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-36329 [Patent Document 3] Japanese Patent Application Publication No. 11-36285 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-319874 Summary of the Invention [Problem to be solved by the invention]

[0008] In threaded joints such as those described in Patent Document 1, even if the threads are multi-threaded, it is unavoidable to rotate the steel pipe during joining, which can make joining difficult when the diameter is very large or when there is insufficient space to work on the rotation.

[0009] Furthermore, in a joint that undergoes elastic deformation as in Patent Document 2, if the joint is thick, the load required to cause elastic deformation increases, and there are cases where the joint cannot be fitted together due to its own weight alone. It is possible to reduce the load by increasing the number of slits or making them longer, but this increases processing costs and reduces the shear load transmission capacity.

[0010] On the other hand, the joint disclosed in Patent Document 3 differs from Patent Documents 1 and 2 in that although a ring-shaped member is required to form the joint, rotation is not required during joining and no load is required to cause elastic deformation.

[0011] However, as mentioned above, the device in Patent Document 3, which uses a ring-shaped member, cannot transmit torsional loads, so it is necessary to either place a bolt as in Patent Documents 1 and 2, or to place a separate anti-rotation mechanism as in Patent Document 4. However, in the case of Patent Document 3, even if a bolt is placed as in Patent Documents 1 and 2, or a separate anti-rotation mechanism is provided as in Patent Document 4, the ring-shaped member itself is rotatable, so there is a concern that the ring-shaped member may behave in an unexpected manner when used in common, causing the joint to come off or reducing the strength.

[0012] The present invention has been made to solve these problems, and aims to provide a mechanical joint that does not require rotation or application of a large load to the joint, can transmit torsional loads without incurring excessive additional costs, and does not come loose or reduce yield strength. Another object of the present invention is to provide a method for joining the mechanical joint, a steel pipe equipped with the mechanical joint, a structure including the steel pipe as a component, a construction method for the structure, a design method for the mechanical joint, and a manufacturing method for the mechanical joint. [Means for solving the problem]

[0013] (1) The mechanical joint according to the present invention comprises a tubular male joint and a female joint into which the male joint is inserted and fitted, and is attached to the end of a steel pipe to join the steel pipes together, a stepped portion is formed on the base end side of the male joint, and when the male joint is inserted into the female joint, the tip end of the female joint abuts on the stepped portion to reach an insertion complete state; one or more stepped annular grooves are formed on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion complete state; a C-shaped ring member that can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and that can be positioned within the annular groove so as to straddle both the male joint side and the female joint side in the insertion complete state; anti-rotation pin insertion holes provided in the male joint and the female joint at positions that coincide with the C-shaped notch in the C-shaped ring member; and an anti-rotation pin that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint in the insertion complete state, and reaches the anti-rotation pin insertion hole of the male joint.

[0014] (2) Furthermore, a method for joining a mechanical joint according to the present invention is the method for joining a mechanical joint described in (1) above, a step of expanding the diameter of the C-ring and accommodating it in the annular groove of the female joint while aligning the C-shaped notch with the rotation prevention pin insertion hole of the female joint; a step of bringing the male joint and the female joint into an insertion complete state in a state in which the positions of the rotation prevention pin insertion holes of the male joint and the female joint are aligned; releasing the C-ring from its expanded state; and disposing the anti-rotation pin so that it passes through the anti-rotation pin insertion hole and the C-shaped notch and reaches the anti-rotation pin insertion hole of the male joint.

[0015] (3) Furthermore, the steel pipe according to the present invention has the male joint and female joint described in (1) attached to one end and the other end thereof.

[0016] (4) Furthermore, the structure according to the present invention comprises a plurality of steel pipes connected by the mechanical joint described in (1) above.

[0017] (5) Furthermore, the construction method of the structure according to the present invention is a construction method of the structure described in (4) above, in which, while restraining the position of one of the jointed steel pipes to be connected in the axial direction of the steel pipe, the other jointed steel pipe is aligned with the one jointed steel pipe and inserted and fitted.

[0018] (6) Furthermore, a design method for a mechanical joint according to the present invention is a design method for a mechanical joint that includes a tubular male joint and a female joint into which the male joint is inserted and fitted, and that is attached to the end of a steel pipe to join two steel pipes, and includes the steps of: a step portion is provided on the base end side of the male joint; When the male joint is completely inserted into the female joint, the tip end of the female joint is set to abut against the step portion, One or more stages of annular grooves are arranged on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is set so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; anti-rotation pin insertion holes are provided in the male joint and the female joint at positions that coincide with the C-shaped notch portions of the C-shaped ring member, In the insertion complete state, an anti-rotation pin is set to pass through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reach the anti-rotation pin insertion hole of the male joint.

[0019] (7) Furthermore, a method for manufacturing a mechanical joint according to the present invention is a method for manufacturing a mechanical joint that includes a tubular male joint and a female joint into which the male joint is inserted and fitted, and that is attached to the end of a steel pipe to join two steel pipes, A step portion is formed on the base end side of the male joint, The male joint is formed so that a tip end of the female joint abuts on the step portion when the male joint is completely inserted into the female joint, One or more annular grooves are formed on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is formed so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; An anti-rotation pin insertion hole is formed in the male joint and the female joint at a position that coincides with the C-shaped notch portion of the C-shaped ring member, In the insertion completed state, an anti-rotation pin is formed which passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint. [Effects of the Invention]

[0020] In the present invention, annular grooves are provided in the male joint and the female joint, and when the male joint is fully inserted into the female joint, a C-shaped ring member is positioned so as to straddle the annular grooves of both the male joint and the female joint, and an anti-rotation pin is provided that passes through the anti-rotation pin insertion hole and C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint when insertion is complete.This eliminates the need to apply rotation or large loads to the joint, and allows torsional loads to be transmitted without incurring additional excessive costs. Furthermore, since the anti-rotation pin not only prevents rotation of the male and female joints, but also prevents movement of the C-ring member, the cutout portion of the C-ring is always visible from the anti-rotation pin insertion hole of the female joint, making it easy to expand the diameter of the C-ring when removing the joints. [Brief explanation of the drawings]

[0021] [Figure 1] 1(a) is an explanatory diagram of a mechanical joint according to embodiment 1, in which FIG. 1(a) is a vertical cross-sectional view (upper view in the figure (same below)) and a cross-sectional view taken along the line AA in the vertical cross-sectional view (lower view in the figure (same below)), FIG. 1(b) is a vertical cross-sectional view and a cross-sectional view taken along the line BB in the vertical cross-sectional view, FIG. 1(c) is a vertical cross-sectional view and a cross-sectional view taken along the line CC in the vertical cross-sectional view, and FIG. 1(d) is a vertical cross-sectional view and a cross-sectional view taken along the line DD in the vertical cross-sectional view. [Figure 2] 10 is an explanatory view of another aspect of the method for expanding the diameter of the C-ring member in the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] A mechanical joint according to this embodiment will be described with reference to Fig. 1. Fig. 1(a) shows the state before the joint is inserted, Fig. 1(b) shows the state after the joint has been inserted and before the C-ring member has been expanded and released, Fig. 1(c) shows the state after the C-ring member 17 has been expanded and released and before the anti-rotation pin has been inserted, and Fig. 1(d) shows the state after the anti-rotation pin 11 has been inserted.

[0023] As shown in Figure 1(a), the mechanical joint 1 according to this embodiment comprises a tubular male joint 3 and a female joint 5 into which the male joint 3 is inserted and fitted, and is attached to the ends of steel pipes 7 to join the steel pipes 7 together. A step portion 9 is formed on the base end side of the male joint 3, and as shown in Figure 1(b), when the male joint 3 is inserted into the female joint 5, the tip portion 10 of the female joint 5 abuts against the step portion 9, thereby completing the insertion.

[0024] Further, the male joint 3 and the female joint 5 are provided with anti-rotation pin insertion holes 13M, 13F for inserting an anti-rotation pin 11 therein. The anti-rotation pin insertion holes 13M, 13F may be tapped holes on both the male joint 3 and the female joint 5, or may be threaded holes on only one of the male joint 3 or the female joint 5. However, if one of them is a threaded hole, it is preferable to make the male joint 3 side a threaded hole, as this makes it easier to expand the diameter of the C-ring member.

[0025] Furthermore, annular grooves 15 are formed on the outer peripheral surface of the male joint 3 and the inner peripheral surface of the female joint 5 so as to face each other when the insertion is complete. The annular grooves 15M, 15F formed in the male joint 3 and the female joint 5 respectively form an annular groove 15 consisting of an annular closed space when the joints are in the fully inserted state. Furthermore, it has a C-shaped ring member 17 that is stored in an expanded diameter state in the annular groove 15F of the female joint 5 so as not to hinder the insertion of the male joint 3 into the female joint 5, and that can be positioned within the annular groove 15 so as to straddle the annular groove 15M of the male joint 3 and the annular groove 15F of the female joint 5 when the expanded diameter state is released. Since the C-shaped ring member 17 is stored in the annular groove 15F of the female joint 5, the depth of the annular groove 15F is equal to or slightly deeper than the radial thickness of the C-shaped ring member 17. On the other hand, the depth of the annular groove 15M of the male joint 3 is set to accommodate half the thickness of the reduced diameter C-shaped ring member 17.

[0026] 1, the C-shaped ring member 17 has a notch 19 at one location in the circumferential direction and has a spring structure that expands and contracts in the radial direction. When the C-shaped ring member 17 is in a free, unconstrained state, its diameter is smaller than the outer diameter of the annular groove 15F. Therefore, in order for the entire C-shaped ring member 17 to be completely housed in the annular groove 15F, a diameter expansion holding means is required to keep the C-shaped ring member 17 in an expanded diameter state.

[0027] 1(a) and 1(b), an example of the diameter expansion holding means is a jig 21 that is disposed in the expanded notch 19 to hold the C-ring member 17 in an expanded state after the notch 19 has been expanded. The jig 21 accesses the C-ring member 17 in the annular groove 15F through the anti-rotation pin insertion hole 13F of the female joint 5 to hold the C-ring member 17 in an expanded state. As a result, the C-ring member 17 is disposed in the annular groove 15F of the female joint 3 while following the outer peripheral surface of the annular groove 15F. As described above, the jig 21 accesses the C-shaped ring member 17 through the anti-rotation pin insertion hole 13F of the female joint 5, so when storing the C-shaped ring member 17 in the annular groove 15F, it is necessary to align the cutout portion 19 with the position of the anti-rotation pin insertion hole 13F.

[0028] The fitting operation of the mechanical joint 1 configured as above will now be described. Before inserting the male joint 3 into the female joint 5, as shown in Figure 1(a), the C-shaped ring member 17 is stored in the annular groove 15F of the female joint 3 in an expanded state, and a jig 21 is used to prevent the diameter of the C-shaped ring member 17 from decreasing. Then, the male joint 3 and the female joint 5 are aligned, and the male joint 3 is inserted into the female joint 5. Incidentally, aligning the directions of the male joint 3 and the female joint 5 means that the positions of the rotation prevention pin insertion holes 13M, 13F of the male joint 3 and the female joint 5 are aligned.

[0029] 1(b), insertion of the male joint 3 into the female joint 5 is completed when the step portion 9 of the male joint 3 and the tip of the female joint 5 are in contact. In this state, the annular grooves 15 formed in the male joint 3 and the female joint 5 form an annular groove 15 consisting of a circular closed space, and the C-ring member 17 stored in the annular groove 15F of the female joint 5 is positioned opposite the annular groove 15M of the male joint 3.

[0030] Next, the jig 21 is removed from the anti-rotation pin insertion hole 13F of the female joint 5 (FIG. 1(b)). As a result, as shown in FIG. 1(c), the C-shaped ring member 17 is contracted in diameter by its own spring force, and the C-shaped ring member 17 is positioned so as to straddle both the annular groove 15M and the annular groove 15F.

[0031] Next, the anti-rotation pin 11 is disposed so that it passes through the anti-rotation pin insertion hole 13F and the notch 19 of the female joint 5 and reaches the anti-rotation pin insertion hole 13M of the male joint 3 (Fig. 1(d)). As a result, the female joint 5 and the male joint 3 are restricted from relative rotational movement by the rotation prevention pin 11, and the C-ring member 17 is prevented from moving within the annular groove 15 by the rotation prevention pin 11.

[0032] In this state, the compressive force is transmitted mainly by the contact pressure between the step portion 9 of the male joint 3 and the tip portion 10 of the female joint 5, the tensile force is transmitted mainly by the support pressure of the C-ring member 17, the torsional force is transmitted by the anti-rotation pin 11, and the shear force is transmitted mainly by the double pipe portion formed by the male joint 3 and the female joint 5.

[0033] As described above, in this embodiment, annular grooves 15M, 15F are provided in the male joint 3 and the female joint 5, and when the male joint 3 is completely inserted into the female joint 5, the C-shaped ring member 17 is arranged to straddle the annular grooves 15 of both the male joint 3 and the female joint 5, and by providing an anti-rotation pin 11, there is no need to apply rotation or large loads to the joint, and tensile loads, torsional loads, and shear loads can be transmitted without incurring excessive additional costs. Furthermore, as described above, the C-shaped ring member 17 is prevented from moving by the rotation prevention pin 11, so that the C-shaped ring member 17 will not move unexpectedly. Furthermore, the anti-rotation pin 11 serves both to prevent rotation of the male joint 3 and female joint 5 and to prevent movement of the C-ring member 17, so reliable load transmission is possible with a simple structure.

[0034] In the above embodiment, the C-shaped ring member 17 is arranged horizontally, i.e., arranged perpendicular to the axes of the male joint 3 and the female joint 5. However, the present invention is not limited to this, and the C-shaped ring member 17 may be arranged at an angle. In this case, the annular grooves 15M, 15F provided in the male joint 3 and the female joint 5 may be arranged at an angle. When the annular groove 15 is inclined, the C-shaped ring member 17 may be formed into an elliptical shape so that it can be stored in the inclined annular groove 15 .

[0035] In the above embodiment, the jig 21 is exemplified as the diameter expansion holding means for holding the C-ring member 17 in an expanded diameter state, but instead of this, for example, a strong magnet 23 may be used. Figure 2 shows a state in which multiple holes (five in Figure 2) are drilled at positions corresponding to the annular groove 15 in the female fitting 5, and powerful magnets 23 are set in these holes to expand the diameter of the C-shaped ring member 17 by attraction and store it in place. In this case, by removing the magnet after the joint is inserted, the C-shaped ring member 17 is reduced in diameter and positioned so as to straddle the male joint 3 and the female joint 5.

[0036] Furthermore, in the above embodiment, the annular groove 15 is formed in one stage, but the present invention is not limited to this, and the annular groove 15 may have multiple stages in the central axial direction of the joint. By using multiple stages, it becomes possible to transmit a larger load.

[0037] Furthermore, the above embodiment is directed to a mechanical joint 1 that is fixed to the end of a steel pipe 7 by welding or the like, but by attaching such a mechanical joint 1 to one end and the other end of a steel pipe 7, a steel pipe 7 that can be easily joined can be constructed. Furthermore, by connecting steel pipes 7 to which mechanical joints 1 are attached, a structure joined by mechanical joints 1 can be constructed. Furthermore, to construct such a structure, the axial position of one of the jointed steel pipes 7 to be connected is restrained, and the other jointed steel pipe 7 is aligned with the one jointed steel pipe 7 and inserted and fitted together.

[0038] Furthermore, although the above embodiment relates to the mechanical joint 1 as an invention of a product, it can also be reconstructed as an invention of a design method or an invention of a manufacturing method, in which case it would be as follows.

[0039] <Invention of design method> A design method for a mechanical joint comprising a tubular male joint and a female joint into which the male joint is inserted and fitted, the mechanical joint being attached to the end of a steel pipe to join the steel pipes, a step portion is provided on the base end side of the male joint; When the male joint is completely inserted into the female joint, the tip end of the female joint is set to abut against the step portion, One or more stages of annular grooves are arranged on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is set so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; anti-rotation pin insertion holes are provided in the male joint and the female joint at positions that coincide with the C-shaped notch portions of the C-shaped ring member, A method for designing a mechanical joint that sets an anti-rotation pin that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint in the insertion-completed state.

[0040] <Invention of manufacturing method> A method for manufacturing a mechanical joint comprising a tubular male joint and a female joint into which the male joint is inserted and fitted, the female joint being attached to the end of a steel pipe to join the steel pipes, A step portion is formed on the base end side of the male joint, The male joint is formed so that a tip end of the female joint abuts on the step portion when the male joint is completely inserted into the female joint, One or more annular grooves are formed on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is formed so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; An anti-rotation pin insertion hole is formed in the male joint and the female joint at a position that coincides with the C-shaped notch portion of the C-shaped ring member, A method for manufacturing a mechanical joint, in which an anti-rotation pin is formed that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint in the inserted state. [Explanation of symbols]

[0041] 1 Mechanical coupling 3 Male joint 5 female fitting 7 Steel pipe 9 Step 10 Tip 11 Anti-rotation pin 13M Anti-rotation pin insertion hole (male joint) 13F Anti-rotation pin insertion hole (female joint) 15 Annular groove 15M Annular Groove (Male Joint) 15F Annular groove (female fitting) 17 C-ring member 19 Notch 21 Jig 23 Magnet

Claims

1. A mechanical joint comprising a tubular male joint and a female joint into which the male joint is inserted and fitted, the mechanical joint being attached to the end of a steel pipe to join the steel pipes together, a stepped portion is formed on the base end side of the male joint, and when the male joint is inserted into the female joint, the tip end of the female joint abuts on the stepped portion, thereby reaching an insertion complete state; one or more stepped annular grooves are formed on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion complete state; a C-shaped ring member that can be stored in the annular groove of the female joint so as not to hinder the insertion of the male joint into the female joint, and that can be positioned within the annular groove so as to straddle both the male joint side and the female joint side in the insertion complete state; anti-rotation pin insertion holes provided in the male joint and the female joint at positions that coincide with C-shaped notches in the C-shaped ring member; and an anti-rotation pin that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint in the insertion complete state,

2. A method for joining a mechanical joint according to claim 1, a step of expanding the diameter of the C-ring and accommodating it in the annular groove of the male joint while aligning the C-shaped notch with the anti-rotation pin insertion hole of the male joint; a step of bringing the male joint and the female joint into an insertion complete state in a state in which the positions of the rotation prevention pin insertion holes of the male joint and the female joint are aligned; releasing the C-ring from its expanded state; and arranging the anti-rotation pin so that it passes through the anti-rotation pin insertion hole and the C-shaped notch and reaches the anti-rotation pin insertion hole of the male joint.

3. A steel pipe having the male and female joints according to claim 1 attached to one end and the other end thereof.

4. A structure comprising a plurality of steel pipes connected by the mechanical joint according to claim 1.

5. 5. A method for constructing a structure as described in claim 4, in which, while restraining the axial position of one of the jointed steel pipes to be connected, the other jointed steel pipe is aligned with the one jointed steel pipe and inserted and fitted.

6. A design method for a mechanical joint that includes a tubular male joint and a female joint into which the male joint is inserted and fitted, and that is attached to the end of a steel pipe to join two steel pipes, comprising: a step portion is provided on the base end side of the male joint; When the male joint is completely inserted into the female joint, the tip end of the female joint is set to abut against the step portion, One or more stages of annular grooves are arranged on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is set so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; anti-rotation pin insertion holes are provided in the male joint and the female joint at positions that coincide with the C-shaped notch portions of the C-shaped ring member; A method for designing a mechanical joint that sets an anti-rotation pin that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint in the insertion-completed state.

7. A method for manufacturing a mechanical joint comprising a tubular male joint and a female joint into which the male joint is inserted and fitted, the female joint being attached to the end of a steel pipe to join the steel pipes, A step portion is formed on the base end side of the male joint, The male joint is formed so that a tip end of the female joint abuts on the step portion when the male joint is completely inserted into the female joint, One or more annular grooves are formed on the outer peripheral surface of the male joint and the inner peripheral surface of the female joint so as to face each other in the insertion completion state, a C-shaped ring member is formed so that it can be stored in the annular groove of the female joint so as not to interfere with the insertion of the male joint into the female joint, and so that it can be arranged within the annular groove so as to straddle the male joint side and the female joint side when the insertion is complete; An anti-rotation pin insertion hole is formed in the male joint and the female joint at a position that coincides with the C-shaped notch portion of the C-shaped ring member, A method for manufacturing a mechanical joint, in which an anti-rotation pin is formed that passes through the anti-rotation pin insertion hole and the C-shaped notch of the female joint and reaches the anti-rotation pin insertion hole of the male joint in the inserted state.

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