JP2018165520A - Steel pipe connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify pretreatment for steel pipe in connecting steel pipes with a mechanical joint.SOLUTION: A steel pipe connection structure 10 has a first member 11 inserted into a steel pipe on the side surface of which an aperture is formed, and a second member 12 inserted into the first member 11. The first member 11 has a projection 111 projecting from an outer peripheral surface 110 and fitted into the aperture, and a pressed surface 112 formed on an inner periphery. An outer diameter of the first member 11 formed by the outer peripheral surface 110 is expandable. The second member 12 has a pressing surface 122 formed on an outer periphery and configured to press the pressed surface 112.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel pipe connection structure.

  Steel pipes have a variety of uses, one of which is a use as a structural member of a building or a civil engineering structure. For example, when a long structural member such as a pile is composed of a steel pipe, construction in a limited space becomes possible by connecting the short steel pipe in the field to make a long structural member. It is also easy to transport the steel pipe up to. For example, in the case of a small-diameter steel pipe having a diameter of about 50 mm to 200 mm, if it is short, it can be handled manually.

  In such a case, one of the most common methods for connecting steel pipes is welding. However, the welding process is relatively time consuming and requires a skilled welder. Therefore, the process of welding a short steel pipe on site to make a long structural member tends to be a construction bottleneck in terms of construction period and personnel planning. Therefore, various steel pipe connection structures using mechanical joints that do not require an on-site welding process have been proposed.

  For example, Patent Document 1 describes a technique of mechanically connecting steel pipes by fitting a pair of connecting members welded to end faces of the respective steel pipes to each other. In this case, since the steel pipe and the connecting member can be welded at a factory, no on-site welding process is required. Patent Document 2 describes a technique of mechanically connecting steel pipes by engaging a connecting member from the outside with a flange formed at an end of each steel pipe.

Japanese Patent Laying-Open No. 2015-143466 Japanese Patent Laying-Open No. 2015-132106

  The conventional steel pipe connection structure as described above is advantageous in that it does not require an on-site welding process. However, for example, in the case of a small-diameter steel pipe in which the advantage of shortening can be easily obtained as described above, since the thickness of the steel pipe is thin, it is not easy to perform complicated processing on the steel pipe in advance. Specifically, a connecting member is welded to the end surface of the steel pipe as in the technique described in Patent Document 1, or a flange is formed at the end of the steel pipe as in the technique described in Patent Document 2. For example, it is not easy in the case of a small diameter steel pipe.

  Accordingly, an object of the present invention is to provide a new and improved steel pipe connection structure capable of simplifying the prior processing for a steel pipe when connecting the steel pipe using a mechanical joint. .

According to some aspects of the invention, the following is provided.
[1] including a first member inserted inside a steel pipe having an opening formed on a side surface, and a second member inserted inside the first member,
The first member has a protrusion that protrudes from the outer peripheral surface and fits into the opening, and a pressed surface formed on the inner periphery, and the outer diameter of the first member formed by the outer peripheral surface is freely expandable and contractable. ,
The second member has a pressing surface that is formed on the outer periphery and presses the pressed surface.
[2] The outer diameter of the first member is freely expandable / contractable from a first outer diameter smaller than the inner diameter of the steel pipe by at least the height of the projection to a second outer diameter equal to the inner diameter of the steel pipe. The connection structure of the steel pipe as described in [1].
[3] The steel pipe connection structure according to [1] or [2], wherein the first member is divided into a plurality of portions in the circumferential direction, and a gap is provided between the plurality of portions.
[4] The steel pipe connection structure according to any one of [1] to [3], wherein the pressing surface and the pressed surface are tapered surfaces having shapes corresponding to each other.
[5] The steel pipe connection structure according to any one of [1] to [4], wherein thread shapes corresponding to each other are formed on an inner periphery of the first member and an outer periphery of the second member.
[6] The steel pipe connection structure according to any one of [1] to [5], wherein an adhesive layer is formed between the pressing surface and the pressed surface.
[7] The steel pipe connection structure according to any one of [1] to [6], wherein the protrusion has a cross-sectional shape extending in an axial direction of the steel pipe.
[8] The steel pipe connection structure according to any one of [1] to [7], wherein the protrusion includes a plurality of protrusions arranged in an axial direction of the steel pipe.
[9] The steel pipe connection structure according to [8], wherein the positions of the plurality of protrusions are shifted in the circumferential direction of the steel pipe.

  ADVANTAGE OF THE INVENTION According to this invention, in connecting a steel pipe using a mechanical coupling, the prior process with respect to a steel pipe can be simplified.

It is a schematic perspective view which shows the member of the connection structure which concerns on 1st Embodiment of this invention. It is a figure which shows the connection process of the steel pipe by the connection structure shown by FIG. It is a figure for demonstrating the force which acts on the connection structure shown by FIG. It is a figure which shows the modification of the cross-sectional shape of the processus | protrusion and opening in the connection structure shown by FIG. It is a figure which shows the modification of the cross-sectional shape of the processus | protrusion and opening in the connection structure shown by FIG. It is a schematic perspective view which shows the member of the connection structure which concerns on 2nd Embodiment of this invention. It is a schematic perspective view which shows the member of the connection structure which concerns on 3rd Embodiment of this invention. It is a rough sectional view showing the connection structure concerning a 4th embodiment of the present invention. It is a rough sectional view showing the connection structure concerning a 5th embodiment of the present invention. It is a rough sectional view showing the connection structure concerning a 6th embodiment of the present invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
FIG. 1 is a schematic perspective view showing members of a connection structure according to the first embodiment of the present invention. The connection structure 10 shown in FIG. 1 includes a first member 11 inserted inside the steel pipe and a second member 12 inserted inside the first member 11.

  The first member 11 has a protrusion 111 protruding from the outer peripheral surface 110. The outer peripheral surface 110 has a shape corresponding to the inner peripheral surface of the steel pipe, and contacts the inner peripheral surface of the steel pipe when the first member 11 is inserted inside the steel pipe. At this time, the protrusion 111 is fitted into an opening formed on the side surface of the steel pipe. On the other hand, the second member 12 has a rod shape or a cylindrical shape as a whole, but a tapered surface 122 is formed on the outer periphery. The second member 12 is inserted inside the first member 11, and the tapered surface 122 of the second member 12 presses the tapered surface 112 formed on the inner periphery of the first member 11. The tapered surface 112 of the first member 11 is a pressed surface that is pressed by the tapered surface 122 of the second member 12. Here, it means a surface that continuously changes in the tube axis direction of the steel pipe to which the diameter of the taper member (the inner diameter in the first member 11 and the outer diameter in the second member 12) is connected. The tapered surfaces 112 and 122 have shapes corresponding to each other. In the illustrated example, a straight surface 113 continuous with the tapered surface 112 is formed on the inner periphery of the first member 11. Here, the straight surface means a surface in which the diameter of the member (inner diameter in the first member 11) is constant in the tube axis direction of the steel pipe to be connected. The straight surface 113 is formed, for example, when the weight balance needs to be improved by adjusting the length of the first member 11 in the tube axis direction (that is, the axial direction of the steel pipe). Further, the first member 11 may have a flange 114 that rises outward from one end of the outer peripheral surface 110.

  Here, although the 1st member 11 is cylindrical as a whole, it is divided | segmented into several parts about the circumferential direction (namely, circumferential direction of a steel pipe), specifically two parts 11a and 11b, and parts 11a and 11b. A predetermined gap is provided between the two. With this structure, the outer diameter of the first member 11 can be expanded and contracted. In the following description, the outer diameter of the first member 11 means the outer diameter formed by the outer peripheral surface 110 excluding the protrusions 111. As will be described later, in the present embodiment, the outer diameter of the first member 11 corresponds to the inner diameter of the steel pipe from the first outer diameter that is smaller than the inner diameter of the steel pipe by at least the height of the protrusion 111 or substantially. Expanded to an equal second outer diameter.

  In the present embodiment, when the tapered surface 122 of the second member 12 presses the tapered surface 112 of the first member 11, an adhesive layer (not shown) is formed between the tapered surface 112 and the tapered surface 122. Maintained by. The adhesive layer is formed, for example, by applying an adhesive to one or both of the tapered surfaces 112 and 122.

  2 (A) to 2 (C) are diagrams showing a steel pipe connecting step by the connecting structure shown in FIG. In the illustrated example, a pair of first members 11 (parts 11a and 11b and parts 11c and 11d) and a second member 12 (having tapered surfaces 122a and 122b formed in opposite directions) are used. A pair of steel pipes 2 (steel pipe 2a and steel pipe 2b) are connected.

First, as shown to FIG. 2 (A), the 1st member 11 (part 11a, 11b) is inserted inside the steel pipe 2a. At this time, the outer diameter _{D C} of the first member 11 (the portion 11a, 11b) is deflated to the first outer diameter smaller than the inner diameter _{d P} of the amount corresponding steel pipe 2a of the height H of at least the protrusion 111 _{(i.e., D C <d P -2H)} . Therefore, even if the protrusion 111 protrudes from the outer peripheral surface 110, it is easy to insert the first member 11 (parts 11a and 11b) into the steel pipe 2a. In the illustrated example, the flange 114 abuts against the end surface 2e of the steel pipe 2a, whereby the position of the first member 11 (parts 11a, 11b) in the pipe axis direction is fixed. In the circumferential direction, the first member 11 (parts 11a and 11b) is aligned so that the protrusion 111 is aligned with the opening 2h formed on the side surface of the steel pipe 2a. In the case where the insertion portion 11a of the first member, a 11b, one by one separately steel 2a is not necessarily required to satisfy the relation of _D C _<d P -2H.

Next, as shown in FIG. 2B, the second member 12 is inserted inside the first member 11 (parts 11a and 11b). By this time, first member 11 (the portion 11a, 11b) the outer diameter _{D C} of allowed to expand to substantially equal second outer diameter to the inner diameter _{d P} of the steel tube 2a, the projection 111 is fitted into the opening 2h ing. For example, the outer diameter of the first member 11 may be manually expanded after being inserted inside the steel pipe 2a as shown in FIG. 2 (A), and then the second member 12 may be inserted. Alternatively, the outer diameter of the first member 11 remains contracted to the first outer diameter even after being inserted inside the steel pipe 2a, and the second member 12 is inserted until the second outer diameter is reached. It may be expanded. When the second member 12 is inserted inside the first member 11, the tapered surface 122a of the second member 12 presses the tapered surface 112 of the first member 11 (parts 11a and 11b). Accordingly, the first member 11 (parts 11a and 11b) is fixed to the steel pipe 2a in a state where the protrusion 111 is fitted in the opening 2h.

  Further, as shown in FIG. 2 (C), the first member 11 (parts 11c, 11d) is also inserted inside the other steel pipe 2b, and the second member 12 is inserted inside thereof. Similar to the process shown in FIG. 2B, the tapered surface 122b of the second member 12 presses the tapered surface 112 of the first member 11 (parts 11c and 11d), thereby causing the first member 11 (parts 11c and 11c, 11d) is also fixed to the steel pipe 2b in a state where the projection 111 is fitted in the opening 2h.

  In the illustrated example, the protrusion 111 of the first member 11 inserted inside is fitted into the opening 2h for both the steel pipes 2a and 2b. Thereby, the 1st member 11 can be fixed to steel pipes 2a and 2b. Further, a common second member 12 is inserted inside both the first members 11, and the first member 11 and the second member 12 are fixed by an adhesive layer. Thus, the connection structure 10 which concerns on this embodiment connects the steel pipe 2a and the steel pipe 2b.

2A to 2C, the overall cross-sectional shape of the first member 11 is changed from a shape close to an ellipse to a shape close to a circle, or from a shape close to a circle to an ellipse. It changes to a shape close to. Therefore, the outer diameter D _C of the first member 11 is not always defined as the diameter of a circle. As described above, the first member 11, since by contracting and expanding the outer diameter D _C is intended to fit the projection 111 into the opening 2h of the steel pipe 2, the projections 111 on the outer diameter D _C You may define as an outer dimension of the outer peripheral surface 110 on the basis of the part formed. Thereby, the minimum value of the outer diameter _{D C} in view of the height H of the internal diameter _{d P} and the projection 111 of the steel pipe 2a (state shown in FIG. 2 (A)) and the maximum value (see FIG. 2 (B) and (C And the shape of the first member 11 can be designed.

FIG. 3 is a diagram for explaining the force acting on the connection structure shown in FIG. 1. FIG. 3 shows the shearing force S acting on the protrusion 111 of the first member 11 that fits into the opening 2 h formed in the steel pipe 2. As described above, in this embodiment, the tensile load in the axial direction of the steel pipe 2 acts as the shearing force S on the protrusion 111, and the protrusion 111 opposes the shearing force S, thereby connecting the steel pipe 2 by the connecting structure 10. Maintained. The maximum shearing force S _max that can be opposed by the protrusion 111 can be expressed by the following equation (1) using the total cross-sectional area A of the protrusion 111 and the yield strength σ of the protrusion 111. The connecting structure 10 needs to be designed so that the maximum shearing force _Smax is larger than the required tensile strength.

S _max = A · σ (1)

  4 (A) to 4 (C) are diagrams showing a modification of the shape (transverse cross-sectional shape) of the protrusion and the opening in the connection structure shown in FIG. Here, the cross-sectional shape is a shape when the protrusion is cut in parallel to the axial direction of the steel pipe 2. As described above with reference to FIG. 3, the connection structure 10 according to the present embodiment maintains the connection of the steel pipes 2 by the protrusions 111 formed on the first member 11 resisting the shearing force S. To do. Therefore, the protrusion 111 needs to have a sufficient cross-sectional area so that it can counter the shearing force S. On the other hand, when the cross-sectional area of the protrusion 111 increases, the opening 2h formed in the steel pipe 2 also increases. If the dimension of the opening 2h in the circumferential direction of the steel pipe 2 becomes too large, the tensile strength in the axial direction of the steel pipe 2 may be lowered. Therefore, when designing the connecting structure 10, it is necessary to determine the cross-sectional shape of the protrusion 111 so that the dimension of the opening 2 h in the circumferential direction can be suppressed while securing the cross-sectional area of the protrusion 111.

  FIG. 4A shows a protrusion 111 similar to the example shown in FIG. 1 and a corresponding opening 2h. In this example, the protrusion 111 and the opening 2h have a substantially circular cross-sectional shape. The substantially circular cross-sectional shape is advantageous in that stress concentration at the contact surface between the protrusion 111 and the opening 2h can be suppressed. If stress concentration on the contact surface is suppressed, cracks are unlikely to occur from the opening 2h when tensile stress is applied to the connecting structure 10.

  FIG. 4B shows a protrusion 111b and an opening 2hb according to a modification. The protrusion 111b and the opening 2hb have an elliptical cross-sectional shape extending in the tube axis direction. The cross-sectional shape extending in the tube axis direction is advantageous in that the dimension of the opening 2hb in the circumferential direction can be suppressed while ensuring the cross-sectional area of the protrusion 111b.

  FIG. 4C shows a protrusion 111c and an opening 2hc according to another modification. The protrusion 111c and the opening 2hc have a rectangular cross-sectional shape extending in the tube axis direction. As described above, the cross-sectional shape extending in the tube axis direction is advantageous in that the dimension of the opening 2hc in the circumferential direction can be suppressed while ensuring the cross-sectional area of the protrusion 111c. In the case of a rectangular cross-sectional shape, it is preferable to round the corners of the rectangle in order to suppress stress concentration.

  FIGS. 5A and 5B are also diagrams showing modifications of the cross-sectional shapes of the protrusions and the openings in the connection structure shown in FIG. However, in the example of FIGS. 5A and 5B, the protrusion 111 includes a plurality of protrusions arranged in the tube axis direction.

  FIG. 5A shows two protrusions 111d1, 111d2 arranged in the tube axis direction and two openings 2hd1, 2hd2 corresponding to these. In the example shown, these protrusions and apertures both have a substantially circular cross-sectional shape, but as in the example described above with reference to FIGS. 4B and 4C, Other cross-sectional shapes may be used. Arranging a plurality of protrusions in the tube axis direction is advantageous in that the dimensions of the respective openings 2hd1 and 2hd2 in the circumferential direction can be suppressed while ensuring the total cross-sectional area of the protrusions 111d1 and 111d2.

  FIG. 5B shows three protrusions 111e1 to 111e3 arranged in the pipe axis direction and shifted in the circumferential direction of the steel pipe 2, and three openings 2he1 to 2he3 corresponding thereto. ing. In the example shown, these protrusions and apertures both have a substantially circular cross-sectional shape, but as in the example described above with reference to FIGS. 4B and 4C, Other cross-sectional shapes may be used. As described above, the arrangement of the plurality of protrusions in the tube axis direction can reduce the dimensions of the respective openings 2he1 to 2he3 in the circumferential direction while ensuring the total cross-sectional area of the protrusions 111e1 to 111e3. It is advantageous. Further, by shifting the positions of the plurality of protrusions in the circumferential direction, it is possible to increase the distance between the protrusions and prevent cracks from occurring in the tube axis direction between the protrusions. Note that the cross-sectional shapes of the protrusions and the apertures are not necessarily the same. For example, in the example of FIG. 5B, the shape of the openings 2he2 and 2he3 of the steel pipe 2 may be larger than the protrusions 111e2 and 111e3 in the circumferential direction. In this example, since the protrusions 111e1 to 111e3 project radially as a whole, the protrusion 111e1 and the opening 2he1 are first fitted by the above structure, and the protrusions 111e2 and 111e3 are later opened to the opening 2he2, It becomes easy to fit 2he3.

  According to the connection structure 10 according to the first embodiment of the present invention described above, the connection of the steel pipe 2 is maintained by fitting the protrusion 111 of the first member 11 into the opening 2h of the steel pipe 2. In this case, the pre-processing for the steel pipe 2 only needs to form the opening 2h having a simple shape. That is, in the present embodiment, complicated processing such as welding a connecting member to the end surface of the steel pipe 2 or forming a flange at the end of the steel pipe 2 is not required. Therefore, for example, even in the case of a small-diameter steel pipe having a thin wall thickness, it is possible to easily realize the connection of the steel pipe 2 using the connection structure 10.

(Second Embodiment)
FIG. 6 is a schematic perspective view showing members of a connection structure according to the second embodiment of the present invention. The connection structure 20 shown in FIG. 6 includes a first member 21 (including portions 21 a and 21 b) and a second member 22. As a difference from the connection structure 10 according to the first embodiment, a thread 216 is formed on the tapered surface 112 in the first member 21. On the other hand, in the second member 22, a thread groove 226 is provided on the tapered surface 122. Other than that, the connection structure 20 according to the present embodiment has the same configuration as the connection structure 10 according to the first embodiment.

  In the present embodiment, the screw thread 216 of the first member 21 and the screw groove 226 of the second member 22 are screw shapes corresponding to each other. By providing such a screw shape, the rotational force around the tube axis of the second member 22 or the first member 21 can be converted into a propulsive force when the second member 22 is inserted into the first member 21. it can. Therefore, in the present embodiment, the second member 22 is inserted inside the first member 21 inserted inside the steel pipe, and the second member 22 is further rotated around the pipe axis. Accordingly, the second member 22 can be inserted into the first member 21 to press the tapered surface 112 against the tapered surface 122. At this time, the first member 11 and the steel pipe may be rotated instead of the second member 22 or together with the second member 22.

  In the present embodiment, the state in which the tapered surface 122 of the second member 22 presses the tapered surface 112 of the first member 21 can be maintained by the frictional force acting between the screw thread 216 and the thread groove 226. it can. Therefore, in this embodiment, it is not always necessary to form an adhesive layer between the tapered surface 122 of the second member 22 and the tapered surface 112 of the first member 21. However, an adhesive layer may be formed between the tapered surface 122 and the tapered surface 112 for the purpose of, for example, preventing the screws from loosening.

(Third embodiment)
FIG. 7 is a schematic perspective view showing members of a connection structure according to the third embodiment of the present invention. The connection structure 30 shown in FIG. 7 includes a first member 31 (including portions 31a and 31b) and a second member 32. As a difference from the connection structure 10 according to the first embodiment, in the first member 31, a tapered surface 312 and a straight surface 313 are formed on the inner periphery, and a thread 316 is formed on the straight surface 313. On the other hand, in the second member 32, a tapered surface 322 and a straight surface 323 are formed on the outer periphery, and a screw groove 326 is formed on the straight surface 323. Other than that, the connection structure 30 according to the present embodiment has the same configuration as the connection structure 10 according to the first embodiment.

  In the present embodiment, the tapered surface 312 of the first member 31 is a pressed surface and is pressed by the tapered surface 322 of the second member 32 that is a pressing surface. Similar to the first embodiment, when the second member 32 is inserted inside the first member 31, the tapered surface 322 of the second member 32 presses the tapered surface 312 of the first member 31. Further, the thread 316 of the first member 31 and the thread groove 326 of the second member 32 have screw shapes corresponding to each other. Similar to the second embodiment, such a screw shape allows the rotational force around the axis of the second member 32 or the first member 31 to drive the second member 32 into the first member 31. Is converted to Further, the state in which the tapered surface 322 of the second member 32 presses the tapered surface 312 of the first member 31 can be maintained.

  When the connecting structure 20 according to the second embodiment is compared with the connecting structure 30 according to the present embodiment, screw shapes corresponding to each other are formed on the inner periphery of the first member and the outer periphery of the second member. Are common. On the other hand, in the connecting structure 20, the screw shape is formed on the pressing surface and the pressed surface (tapered surfaces 112, 122), whereas in the connecting structure 30, the screw shape is different from the pressing surface and the pressed surface (straight). The points formed on the surfaces 313, 323) are different. In other words, in the connecting structure 20, the pressing surface, the pressed surface, and the screw shape overlap in the tube axis direction, whereas in the connecting structure 30, the pressing surface, the pressed surface, and the screw shape are different. Separated in the tube axis direction. The second embodiment and the third embodiment are selectively used depending on, for example, a thread-shaped processing condition.

(Fourth embodiment)
FIG. 8 is a schematic cross-sectional view showing a connection structure according to the fourth embodiment of the present invention. In the connection structure 40 shown in FIG. 8, a pin hole 417 a or a screw hole 417 b is formed in the first member 41 instead of the protrusion 111. The configuration of the first member 41 is the same as that of the first member 11 of the first embodiment except for the pin hole 417a and the screw hole 417b. The pin hole 417a of the first member 41 is provided at a position corresponding to the opening 2h of the steel pipe 2, and the pin 418 passes through the opening 2h and fits into the pin hole 417a. The screw hole 417b is also provided at a position corresponding to the opening 2h, and the screw 419 passes through the opening 2h and is screwed into the screw hole 417b. In these cases, the pin 418 and the screw 419 are formed on the outer peripheral surface of the first member 41, and subsequently form a protrusion that fits into the opening 2h of the steel pipe 2.

  In the illustrated example, one first member 41 is fixed to the steel pipe 2 using a pin 418, and the other first member 41 is fixed to the steel pipe 2 using a screw 419. The member 41 may be fixed to the steel pipe 2 using the pin 418. Further, both the first members 41 may be fixed to the steel pipe 2 using the screws 419. Between the 1st member 41 and the 2nd member 12, the screw shape similar to said 2nd Embodiment and 3rd Embodiment may be formed.

(Fifth embodiment)
FIG. 9 is a schematic cross-sectional view showing a connection structure according to the fifth embodiment of the present invention. In the connection structure 50 shown in FIG. 9, a pin hole 517 a or a screw hole 517 b is formed in the first member 51 instead of the protrusion 111. Unlike the fourth embodiment, the pin hole 517a and the screw hole 517b formed in the first member 51 are through holes. The configuration of the first member 51 is the same as that of the first member 11 according to the first embodiment except for the pin hole 517a and the screw hole 517b. Further, in the connection structure 50, a pin hole 527 a and a screw hole 527 b are formed in the second member 52. The configuration of the second member 52 is the same as that of the second member 12 of the first embodiment except for the pin hole 527a and the screw hole 527b.

  The opening 2h of the steel pipe 2, the pin hole 517a of the first member 51, and the pin hole 527a of the second member 52 correspond to each other when the second member 52 is inserted inside the first member 51 ( In other words, the pin 518 passes through the opening 2h and the pin hole 517a and fits into the pin hole 527a. Further, the opening 2h, the screw hole 517b of the first member 51, and the screw hole 527b of the second member 52 correspond to each other in a state where the second member 52 is inserted inside the first member 51 (that is, The screw 519 passes through the opening 2h and the screw hole 517b and is screwed into the screw hole 527b. In these cases, the pin 518 and the screw 519 are formed on the outer peripheral surface of the first member 51, and subsequently form a protrusion that fits into the opening 2 h of the steel pipe 2.

  In the illustrated example, one first member 51 is fixed to the steel pipe 2 using a pin 518, and the other first member 51 is fixed to the steel pipe 2 using a screw 519. The member 51 may be fixed to the steel pipe 2 using the pin 518. Moreover, both the 1st members 51 may be fixed to the steel pipe 2 using the screw 519. Between the 1st member 51 and the 2nd member 52, the screw shape similar to said 2nd Embodiment and 3rd Embodiment may be formed.

  Further, in the present embodiment, the pin 518 and the screw 519 have the tapered surface 122 of the second member 52 like the adhesive layer in the first embodiment and the screw shape in the second embodiment and the third embodiment. The first member 51 has a function of maintaining the state where the tapered surface 112 is pressed. In the present embodiment, if the pin 518 and the screw 519 are kept pressed to obtain a sufficient tensile strength in the connection structure 50, the adhesive layer and the screw shape as described above may not be provided.

(Sixth embodiment)
FIG. 10 is a schematic cross-sectional view showing a connection structure according to the sixth embodiment of the present invention. The connection structure 60 shown in FIG. 10 includes the first member 11 and the second member 62 that are the same as those in the first embodiment. The second member 62 includes a hollow portion 627 that penetrates in the tube axis direction. About the other than that, the structure of the 2nd member 62 is the same as that of the 2nd member 12 which concerns on 1st Embodiment.

  When constructing a steel pipe as a structural member, a fluid such as mortar or water, or a construction tool such as a drill may pass through the steel pipe. In such a case, as shown in FIG. 10, by providing the second member 62 with the hollow portion 627, it becomes possible for the fluid and instrument as described above to pass through the connection structure. In addition, it is also possible to provide the same hollow part in 2nd member 22,32,52 in said 2nd Embodiment-5th Embodiment.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above embodiment, the first member is divided into two parts, and a predetermined gap is provided between the two parts, so that the outer diameter can be expanded and contracted. In another embodiment, the first member may be divided into three or more parts, and a predetermined gap may be provided between each part so that the outer diameter can be expanded and contracted. In still other embodiments, the first member may be composed of a single part. In this case, for example, the outer diameter of the first member may be made adjustable by providing a joint structure that can be expanded and contracted in the circumferential direction. Alternatively, the first member may be formed in a C-shaped cross section including a slit in the tube axis direction, and when the second member is inserted, the outer diameter may be made flexible by elastically deforming so that the slit is widened.

  10, 20, 30, 40, 50, 60 ... connection structure 11, 21, 31, 41, 51 ... first member, 110 ... outer peripheral surface, 111 ... projection, 112, 312 ... tapered surface, 114 ... flange, 216 , 316 ... Thread, 12, 22, 32, 52, 62 ... Second member, 122, 322 ... Tapered surface, 226, 326 ... Thread groove, 2 ... Steel pipe, 2e ... End face, 2h ... Open hole, 2s ... Inside Perimeter.

Claims (9)

Including a first member inserted inside a steel pipe having an opening formed in a side surface, and a second member inserted inside the first member;
The first member has a protrusion that protrudes from the outer peripheral surface and fits into the opening, and a pressed surface that is formed on the inner periphery. The outer diameter of the first member formed by the outer peripheral surface is Can be scaled,
The said 2nd member is a connection structure of the steel pipe which has a pressing surface which is formed in the outer periphery and presses the said to-be-pressed surface.   The outer diameter of the first member is freely expandable / contractable from a first outer diameter smaller than the inner diameter of the steel pipe to a second outer diameter corresponding to the inner diameter of the steel pipe by at least the height of the protrusion. The steel pipe connection structure according to claim 1, wherein   The steel pipe connection structure according to claim 1 or 2, wherein the first member is divided into a plurality of portions in a circumferential direction, and a gap is provided between the plurality of portions.   The steel pipe connection structure according to any one of claims 1 to 3, wherein the pressing surface and the pressed surface are tapered surfaces having shapes corresponding to each other.   The steel pipe connection structure according to any one of claims 1 to 4, wherein screw shapes corresponding to each other are formed on an inner periphery of the first member and an outer periphery of the second member.   The steel pipe connection structure according to any one of claims 1 to 5, wherein an adhesive layer is formed between the pressing surface and the pressed surface.   The steel pipe connection structure according to claim 1, wherein the protrusion has a cross-sectional shape extending in an axial direction of the steel pipe.   The steel pipe connection structure according to claim 1, wherein the protrusion includes a plurality of protrusions arranged in an axial direction of the steel pipe.   The steel pipe connection structure according to claim 8, wherein the plurality of protrusions are shifted in position in a circumferential direction of the steel pipe.

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