Cylindrical-body structure

Abstract

To provide means that allows a rod-shaped body to relatively move smoothly in the radial direction and in the circumferential direction, improves connectivity of rod-shaped bodies with each other, and enhances strength against pulling out.SOLUTION: A cylindrical-body structure has an insertion hole that allows rod-shaped bodies to be inserted therein along an axial direction, and connects the rod-shaped bodies by engaging an inner periphery to node parts that are aligned along the axial direction on the rod-shaped bodies, protrude outwards in a radial direction. The cylindrical-body structure comprises along the inner periphery: one or more types of recess parts arranged in a concave shape to be able to mate with the node parts; and a large-diameter surface adjacent in the circumferential direction to the aforesaid recess part. The cylindrical-body structure is formed with guide space parts, which are arranged in the radial direction and a circumferential direction between the large-diameter surface and a largest-diameter part of the rod-shaped body with the rod-shaped body being in an inserted state, and allows, through the guide space, the rod-shaped body to relatively move in the radial direction and the circumferential direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a cylindrical body structure. [Background technology]

[0002] Conventionally, when constructing a reinforced concrete structure, it is necessary to use long rod-shaped rebars to be embedded in the concrete, but the length of the rebars is limited due to transportation restrictions, etc., so they have been joined on-site to achieve longer lengths. Cylindrical joints are used to join the rebars, and the rebars are connected by inserting them into openings at both ends of the joint (see, for example, Patent Document 1). Also disclosed is a reinforcing bar joint that has irregularities on its inner surface that can engage with two reinforcing bars inserted at both ends (see, for example, Patent Document 2). By inserting reinforcing bars into both ends of this type of reinforcing bar joint and rotating it in a predetermined direction relative to the reinforcing bars, the joint can engage with each reinforcing bar in the axial direction and connect the reinforcing bars together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-178365 [Patent Document 2] Patent Publication No. 2021-107675 Summary of the Invention [Problem to be solved by the invention]

[0004] The joint described in Patent Document 1 requires grout to be filled into the rebar receiving portion where the rebar is loosely fitted, which increases the workload at the construction site due to the need to transport and mix the grout. Furthermore, while grout is filled into the rebar receiving portion with the rebar loosely fitted, grout leaks from the openings at both ends of the joint during filling, preventing the joint from being fully filled. Therefore, nuts must be tightened on both ends of the joint to close the openings. These issues pose numerous challenges, including an increased number of required parts and increased work effort, as well as the time required to align the axes of the rebars inserted into the joint. Furthermore, when using the reinforcing bar joint described in Patent Document 2 mentioned above, it is necessary to adjust the orientation of the reinforcing bar when viewed in the axial direction so that the inner surface of the reinforcing bar joint does not interfere with the large diameter surface of the reinforcing bar, and after inserting the reinforcing bar, it is necessary to adjust the insertion depth of the reinforcing bar so that the convex portion of the reinforcing bar fits into the engaging concave surface provided on the inner surface of the reinforcing bar joint. For example, when inserting a rebar into the insertion hole of a joint, the nodes of the rebar may interfere with the inner circumferential surface of the joint and become stuck. This may prevent the rebar from being inserted smoothly into the joint. Furthermore, if the joint needs to be fixed by rotating relative to the rebar even after the rebar has been inserted into the insertion hole, the nodes of the rebar may interfere with the inner circumferential surface of the joint and become stuck when the joint is rotated circumferentially relative to the rebar. This may prevent the joint from being rotated smoothly circumferentially relative to the rebar. Another problem is that the nodes of the rebar are formed with a pitch and phase relationship. However, when the rebar is cut in the axial direction to adjust its length, the cut position does not take into account the pitch and phase relationship. Therefore, it is necessary to adjust the axial position relative to the joint structure.

[0005] The present invention was made through intensive research by the inventors in consideration of the above-mentioned problems, and aims to provide a means of allowing smooth relative movement of rod-shaped bodies in the radial and circumferential directions with a simple structure, improving the connectivity between the rod-shaped bodies, and improving the pull-out strength when embedded in a solidifying fluid such as concrete, mortar, or resin. Another object of the present invention is to make it possible to automatically guide the node to a predetermined axial position even if the rod-shaped body is cut at a position where the relationship between pitch and phase is not taken into consideration in order to adjust the length, thereby eliminating the need for axial position adjustment relative to the cylindrical body structure. [Means for solving the problem]

[0006] In order to solve the above problem, the present invention provides a cylindrical body structure having an insertion hole through which a rod-shaped body can be inserted in the axial direction, and connecting the rod-shaped body by engaging its inner periphery with nodes arranged in a row in the axial direction of the rod-shaped body and protruding radially outward, wherein the inner periphery has at least one type of recessed portion recessed so that the nodes can be fitted into it, and a large diameter surface circumferentially adjacent to the recessed portion, and when the rod-shaped body is inserted, a guide space portion is formed between the large diameter surface and the outermost diameter portion of the rod-shaped body in the radial and circumferential directions, and the guide space portion allows relative movement of the rod-shaped body in the radial and circumferential directions.

[0007] The guide space has a radius of r d1 and the radius of the outermost part of the node of the rod-shaped body is r lmax In this case, r d1 >r lmax The above relationship is satisfied.

[0008] Further, a reduced diameter surface is connected to the circumferential end of the node of the rod-shaped body, and the radius of the node of the rod-shaped body is r l and the radius of the reduced diameter surface is r s In this case, in the node, r lmax ≧r l and on the surface of the reduced diameter, r lmax ≧r sThe above relationship is satisfied.

[0009] The guide space allows the rod-shaped body to rotate in one direction by a predetermined angle as the relative movement of the rod-shaped body in the circumferential direction.

[0010] The guide space allows the rod-shaped body to rotate in the other direction by a predetermined angle as a relative movement of the rod-shaped body in the circumferential direction.

[0011] The predetermined angle for allowing rotation in one direction is larger than the predetermined angle for allowing rotation in the other direction.

[0012] Furthermore, when viewed in a plan view from the axial direction, a virtual line passing through the approximate center of the large diameter surface and the axis is used as a reference line, and the circumferential shape of the large diameter surface is characterized in that different shapes are formed on the side of the engaging rotation direction with the rod-shaped body and the side of the counter-engagement direction with the reference line as a boundary.

[0013] The circumferential shape of the large diameter surface is such that the radius of the large diameter surface is r d1 The arc shape is formed such that the radius is r d1 >r lmax The above relationship is satisfied.

[0014] The circumferential shape of the large diameter surface is such that the radius of the large diameter surface at the location of the boundary is r d0 On the counter-engagement rotation side, the radius of at least the large diameter surface is set to r d2 The arc shape is formed such that the radius is r d2 ≦r lmax <r d0 The above relationship is satisfied.

[0015] The circumferential shape of the large diameter surface is such that, on the counter-engagement direction side, the radius of the large diameter surface is at least r d2 , r d3 The arc shape is formed such that the radius is rd3 ≦r lmax <r d2 The above relationship is satisfied.

[0016] The circumferential shape is characterized in that an arc shape that is approximately a perfect circle with a substantially constant first radius of curvature is formed in a range along the rotational direction on the engagement rotational direction side.

[0017] Furthermore, when the rod-shaped body is rotated relative to the engaging rotation direction, the outer diameter portion of the node portion of the rod-shaped body comes into contact with one of the large diameter surfaces, thereby creating an interference state with the rod-shaped body.

[0018] The circumferential shape is characterized in that, in at least a portion of the range along the rotational direction on the counter-engagement rotational direction side, an arc shape is formed having a second radius of curvature that is smaller than the first radius of curvature.

[0019] The second radius of curvature may have a length shorter than the length of the radius from the axis of the rod-shaped body to the outer diameter portion of the node.

[0020] The circumferential shape of the large diameter surface on the engagement rotation direction side is substantially the same as or similar to the circumferential shape of the large diameter surface at a point symmetrical position with respect to the axis.

[0021] The circumferential shape of the large diameter surface on the counter-engagement rotational direction side is substantially the same as or similar to the circumferential shape of the large diameter surface at a point symmetrical position with respect to the axis.

[0022] Furthermore, when viewed in a plane from the axial direction, the outer peripheral shape is an approximately perfect circle centered on the axis, and when the rod-shaped body is inserted and rotated circumferentially relative to the rod-shaped body, so that the large diameter surface and the outer diameter portion of the node portion of the rod-shaped body come into contact with each other, the sum of the length in the thickness direction of the large diameter surface at the point of contact and the length from the axis of the rod-shaped body to the abutting outer diameter portion satisfies the relationship that becomes the radial length of the approximately perfect circle.

[0023] The recessed portions are arranged in two opposing regions on the inner circumference, spaced apart radially, and have an extension mechanism that can extend somewhat in the opposing direction of the recessed portions, and when viewed in a plane from the axial direction, the extension mechanism is formed with a circumferential length longer than an imaginary arc drawn radially along the circumferential direction of the large diameter surface, and when the rod-shaped body is inserted, a guide space portion is formed that is set radially and circumferentially between the imaginary arc and the outermost diameter portion of the rod-shaped body, and the guide space portion allows relative movement of the rod-shaped body in the radial and circumferential directions.

[0024] Furthermore, when viewed in a plane from the axial direction, the telescopic mechanism is formed in a roughly bellows shape consisting of an inner vertex in the inner diameter direction and an outer vertex in the outer diameter direction in the radial direction along the circumferential direction of the large diameter surface, and the virtual arc is an orbit that the inner vertex describes in the radial direction along the circumferential direction.

[0025] Furthermore, when viewed in a plane from the axial direction, it has a cylindrical structure that is approximately C-shaped, has slits extending in the axial direction, and the concave portions are arranged in two opposing regions spaced apart radially on the inner circumference, and has an expansion / contraction mechanism that can stretch somewhat in the opposing direction of the concave portions, and the expansion / contraction mechanism is characterized in that the distance between the opposing concave portions increases as the spacing between the slits increases.

[0026] The present invention is also characterized in that it further comprises a restricting means for restricting the spacing of the slit from widening when the node of the rod-shaped body is fitted into the recess.

[0027] The regulating means has a first space surrounding the rod-shaped body and a second space surrounding the tubular body structure, the first space having an inner peripheral surface on which a spiral groove capable of threadingly engaging with the node portion of the rod-shaped body is formed, and the second space has an inner peripheral surface surrounding the outer peripheral surface of the tubular body structure and abutting circumferentially against the outer peripheral surface.

[0028] Furthermore, the regulating means is characterized in that, when the spiral groove formed in the first space and the node portion of the rod-shaped body are threadedly engaged, the inner surface of the second space abuts against the outer surface of the tubular body structure, and the inner surface of the tubular body structure presses against the outer surface of the rod-shaped body.

[0029] The inner circumference is also characterized by having engaging protrusions arranged in a row in the axial direction and capable of engaging with the node portion, at least one or more types of concave portions that alternate with the engaging protrusions in the axial direction and are recessed so that the node portion can be fitted into them, and a large diameter surface circumferentially adjacent to the engaging protrusions and the concave portion, and a position regulating portion is provided in the axial middle portion of the large diameter surface to regulate the insertion depth of the rod-shaped body.

[0030] The position restricting portion may have a guide structure for guiding the node of the rod-shaped body into the recess.

[0031] The position restriction portion is characterized in that it is formed in the shape of an intermittent or continuous spiral strip.

[0032] The position restricting portion is formed to protrude radially inward from the large diameter surface, and the height of the protrusion is formed to be approximately the same as the height of the node portion.

[0033] Furthermore, when the rod-shaped body is inserted, a radial and circumferential guide space is formed between the large diameter surface and the outermost diameter part of the rod-shaped body, and the guide space allows relative movement of the rod-shaped body in the radial and circumferential directions.

[0034] The guide space allows the rod-shaped body to rotate in one direction by a predetermined angle as the relative movement of the rod-shaped body in the circumferential direction.

[0035] The guide space allows the rod-shaped body to rotate in the other direction by a predetermined angle as a relative movement of the rod-shaped body in the circumferential direction.

[0036] The predetermined angle for allowing rotation in one direction is larger than the predetermined angle for allowing rotation in the other direction.

[0037] The recessed portion has a non-helical shape, and the non-helical shape is either a symmetrical shape or an asymmetrical shape with respect to the axial direction as an axis of symmetry when viewed in the radial direction.

[0038] The symmetrical shape is characterized in that both ends in the circumferential direction are closed ends, the main body of the tubular structure has an expansion portion that allows the internal space to be expanded, and the expansion portion is capable of transitioning between a state in which the node portion is received in the inner circumference and a state in which the insertion hole is expanded to receive the node portion in the inner circumference.

[0039] The expansion portion is characterized by having an elastic deformation mechanism.

[0040] The asymmetrically shaped recessed portion may have one circumferential end that is open, and may receive the node portion from the open end side.

[0041] The asymmetrically shaped recessed portion may have a closed end at the other circumferential end, and the closed end may restrict circumferential displacement of the node portion.

[0042] The device is also characterized by having an expansion and contraction mechanism that can expand and contract slightly in the opposing direction of the recessed portions that are disposed opposite each other.

[0043] The telescopic mechanism is characterized in that it is formed with a circumferential length longer than an imaginary arc drawn in the radial direction along the circumferential direction of the large diameter surface.

[0044] The expansion mechanism is characterized in that it is formed in a bellows shape in the radial direction along the circumferential direction of the large diameter surface. [Effects of the Invention]

[0045] According to the present invention, a simple structure allows smooth relative movement of the rod-shaped bodies in the radial and circumferential directions, improves the connectivity between the rod-shaped bodies, and improves the pull-out strength when embedded in a solidifying fluid such as concrete, mortar, or resin. Furthermore, according to the present invention, even if the rod-shaped body is cut at a position where the relationship between pitch and phase is not taken into consideration in order to adjust the length, the node portion can be automatically guided to match a predetermined axial position, and axial position adjustment relative to the cylindrical body structure is also unnecessary. [Brief explanation of the drawings]

[0046] [Figure 1] 1A to 1D show a rod-shaped body of this embodiment, where (a) is a front view, (b) is a side view, (c) is a plan view, and (d) is a cross-sectional view taken along the line AA. [Figure 2] 10A and 10B are cross-sectional views showing examples of the shape of a rod-shaped body. [Figure 3] 10A, 10B, and 10C show examples of other shapes of the node portion, where (a) is a front view, (b) is a side view, and (c) is a BB cross-sectional view. [Figure 4] 10A, 10B, and 10C show examples of other shapes of the node portion, where (a) is a perspective view, (b) is a plan view, and (c) is a front view. [Figure 5] 1A and 1B show a joint structure of the present embodiment, in which (a) is a perspective view, (b) is a plan view, (c) is a cross-sectional view taken along line AA in (b), and (d) is a cross-sectional view taken along line BB in (c). [Figure 6] 1A and 1B are plan views showing a state in which a rod-shaped body is inserted into a joint structure, where (a) shows a state in which a rod-shaped body is inserted into the joint structure, and (b) and (c) show a state in which the rod-shaped body is rotated relative to the joint structure. [Figure 7] 10A and 10B are schematic diagrams showing the entry of a node into a recessed portion, where FIG. 10A is a diagram showing the node before it enters the recessed portion, and FIG. 10B is a diagram showing the node when it is fitted into the recessed portion. [Figure 8] Schematic diagrams showing the state before and after engagement between the rod-shaped body and the joint structure, where (a) is a plan view showing the state before engagement, (b) is a plan view showing the state after engagement, (c) is a cross-sectional view in the state of (a), and (d) is a cross-sectional view in the state of (b). [Figure 9] 10A and 10B are diagrams illustrating examples of the shape of a tip portion. [Figure 10] 10A and 10B are diagrams showing other examples of the inner peripheral shape of the cylindrical body. [Figure 11] 10A and 10B are diagrams showing the position of the node before it enters the recessed portion, and FIG. 10B is a diagram showing the position of the node when it is fitted into the recessed portion. [Figure 12] FIG. [Figure 13] 1A and 1B show the connection of two rod-shaped bodies by a joint structure, in which (a) shows the state in which the joint structure is inserted into a first rod-shaped body, (b) shows the state in which the joint structure is rotated relative to the first rod-shaped body, (c) shows the state in which the joint structure is inserted into a second rod-shaped body, and (d) shows the state in which the joint structure is rotated relative to the second rod-shaped body. [Figure 14] 10A and 10B are schematic diagrams showing the entry of a node into a recessed portion, in which (a) is a diagram showing the node being guided by the guide structure, and (b) is a diagram showing the node being fitted into the recessed portion. [Figure 15] 10A and 10B are schematic diagrams showing the entry of a node into a recess in another guide structure, where (a) is a diagram showing the node being guided by the guide structure, and (b) is a diagram showing the node being fitted into the recess. [Figure 16] 1A and 1B show a joint structure having a non-helical recessed portion and a helical recessed portion, where (a) is a perspective view, (b) is a front view, and (c) is a cross-sectional view taken along the line AA of (b). [Figure 17] FIG. 10 is a perspective view showing another example of a joint structure. [Figure 18] 1A, 1B, and 1C show a relative rotation prevention member that engages with a joint structure, in which FIG. 1A is a perspective view, FIG. 1B is a front view, and FIG. 1C is a cross-sectional view. [Figure 19] 1A is a perspective view of a relative displacement prevention member, FIG. 1B is a front view of the same, and FIG. 1C is a cross-sectional view of the same. [Figure 20] 10A and 10B are diagrams showing the connection between the joint structure and the rod-shaped body. [Figure 21] 10A and 10B are diagrams illustrating the installation of a relative rotation prevention member and a relative displacement prevention member. [Figure 22] 10A and 10B are diagrams illustrating another example of a relative rotation prevention member. [Figure 23] 10A and 10B show a joint structure according to a second embodiment, in which FIG. 10A is a perspective view seen from the front, and FIG. 10B is a perspective view seen from the side. [Figure 24] FIG. 10 is a perspective view showing a modified example of the joint structure according to the second embodiment. [Figure 25] FIG. 2 is a view showing the joint structure as viewed in the axial direction. [Figure 26] 10A and 10B are diagrams showing modified examples of a guide structure provided in the joint structure. [Figure 27] FIG. 10 is a front view showing a modified example of the joint structure according to the second embodiment. [Figure 28] 10A to 10C are diagrams showing an example of a procedure for connecting rod-shaped bodies to each other using a joint structure. [Figure 29] 1A and 1B show a restricting means, in which FIG. 1A is a perspective view and FIG. 1B is a longitudinal sectional view. [Figure 30] 10A to 10C are diagrams showing an example of a procedure for connecting rod-shaped bodies to each other using a joint structure. [Figure 31] 10A and 10B are diagrams showing an example in which a joint structure guides a node of a rod-shaped body. DETAILED DESCRIPTION OF THE INVENTION

[0047] Hereinafter, a joint structure as a tubular structure for connecting rod-shaped bodies (steel rods for reinforcing a hydraulically solidified body buried therein) according to a first embodiment of the present invention will be described with reference to the drawings. The joint structure is composed of a member forming a tubular body as a whole, and is connected to rod-shaped bodies inserted into the ends, and the rod-shaped bodies are connected to each other by inserting rod-shaped bodies into both end portions. Therefore, the joint structure has a structure for engaging with the rod-shaped bodies, etc. The dimensions, materials, shapes, and relative arrangements of components described as embodiments or shown in the drawings are merely illustrative and are not intended to limit the scope of the present invention. For example, expressions expressing relative or unambiguous arrangements, such as "in a certain direction," "along a certain direction," "toward a certain direction," "parallel," "orthogonal," "vertical," "center," "concentric," or "coaxial," not only strictly express such arrangements, but also express relative displacements with a tolerance or angle or distance to the extent that the same function is achieved. For example, expressions expressing the equality of things, such as "same," "equal," "uniform," and "equal density," not only express strict equality, but also express tolerances or differences or ratios to the extent that the same function is achieved. For example, expressions expressing shapes such as triangular pyramids, cones, triangular prisms, and cylinders not only express shapes such as triangular pyramids, cones, triangular prisms, and cylinders in the strict geometric sense, but also express shapes including concave and convex portions, chamfered portions, curved portions, rounded portions, etc., to the extent that the same effect is achieved. On the other hand, the expressions "comprise," "formed," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0048] In addition, in the drawings, an XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, for convenience, the X-axis direction and the Y-axis direction are parallel to the radial direction of the rod-shaped body 1 shown in FIG. 1. The Z-axis direction is parallel to the axial direction of the rod-shaped body 1. Furthermore, any direction in which the XY plane defined by the X-axis and Y-axis extends is referred to as the "horizontal direction."

[0049] In the following description, the Z-axis direction is defined as the up-down direction, the positive side (+Z side) of the Z-axis direction is referred to as the "upper side (upper side in the Z-axis direction)," and the negative side (-Z side) of the Z-axis direction is referred to as the "lower side (lower side in the Z-axis direction)." Furthermore, the radial direction centered on the Z-axis is simply referred to as the "radial direction," and the circumferential direction (θ direction) centered on the Z-axis is simply referred to as the "circumferential direction." Note that the terms "radial direction," "circumferential direction," "up-down direction," "upper side," and "lower side" are simply names used for the purpose of explanation and do not limit the actual positional relationship or direction.

[0050] In this specification, "extend" includes not only extending strictly in the axial direction but also extending in a direction tilted at an angle of 45° or less relative to the axial direction, and "extend in the radial direction" includes not only extending strictly in a direction perpendicular to the radial direction but also extending in a direction tilted at an angle of 45° or less relative to the radial direction.

[0051] [Structure of rod-shaped body] FIG. 1 shows a rod-shaped body 1 of this embodiment, with (a) being a front view, (b) being a side view, (c) being a plan view, and (d) being an AA cross-sectional view. The rod-shaped body 1 is a long member that forms, for example, a substantially deformed steel bar or a reinforcing steel bar. In FIG. 1, the rod-shaped body 1 has a substantially elliptical shape when viewed in the Z-axis direction, with the X-axis direction corresponding to the major axis direction and the Y-axis direction corresponding to the minor axis direction. In detail, identically shaped rounded portions are formed at both ends in the major axis direction, and two substantially linear shapes are formed at both ends in the minor axis direction between them. However, the substantially elliptical shape is not limited to this, and also includes a shape that forms an ellipse in a geometric sense or a shape close to it, as well as a shape in which the curvature of one end in the major axis direction is not the same as the curvature of the other end. The rod-shaped body 1 is formed by rotating the rod-shaped body 1 along the axis C shown in FIG. 1(c). r The reduced diameter surfaces 2 are located in two predetermined regions facing each other in the minor axis direction with the axis C r 1(a) and have nodes 4 arranged in a row in the Z-axis direction and protruding radially outward, and recessed surfaces 6 recessed alternately in the Z-axis direction on the nodes 4. The rod-shaped body 1 can be made of an appropriate material such as steel.

[0052] The reduced diameter surface 2 extends in the Z-axis direction (FIG. 1(a)), and extends from the axis C toward the circumferential center of the region. r Radius r from s That is, the axis C of the rod-shaped body 1 shown in FIG. r From the radius r at the circumferential center of the region s The reduced diameter surface 2 has a substantially linear shape when viewed in the Z-axis direction, and may be the width across flats formed on the rod-shaped body 1, for example.

[0053] Concave diameter surface 6 is centered at axis Cr Distance r from v is the axis C at the reduced diameter surface 2 r Distance r from s is set to be within the range of (r s ≧r v For example, the concave surface 6 is formed so as to have a distance corresponding to the radius of the circumferential center or both ends of the reduced diameter surface 2. r The distance from the

[0054] As shown in FIG. 1(b), the node 4 has a tip 10 at its radial end. A ridge 12 forming the tip 10 extends perpendicular to the Z axis, and both ends along the circumferential direction extend toward the reduced diameter surface 2. The node 4 also has four faces 14a to 14d that face in different normal directions. These four faces 14a to 14d are each perpendicular to the axis C of the rod-shaped body 1. r The spiral is formed along an imaginary spiral surface assumed around the

[0055] The four surfaces 14a to 14d form a substantially quadrangular pyramid shape when the outer circumferential surface of the rod-shaped body 1 is unfolded (unfolded) onto an imaginary plane. Of the four surfaces 14a to 14d, the upper left in the orientation shown in FIG. 1(b) is surface 14a, the lower left is surface 14b, the upper right is surface 14c, and the lower right is surface 14d.

[0056] Ridges 12, which form boundaries between surfaces 14a and 14b and between surfaces 14c and 14d, extend perpendicular to the Z-axis direction, with both ends facing reduced diameter surface 2. Furthermore, surfaces 14a to 14d have a shape that narrows in the Z-axis direction of rod-shaped body 1 toward the circumferential end located on the reduced diameter surface 2 side. Therefore, the circumferential end of node 4 forms a sharp tip 10.

[0057] The cross-sectional shape of the tip 10 may be substantially acute-angled or substantially obtuse-angled, or may be substantially arc-shaped, or may be a minute flat surface or minute arc-shaped.

[0058] The node 4 and the concave surface 6 shown in FIG. 1(a) are aligned with the axis C rIn each region, the positions of the nodes 4 and the concave surfaces 6 in the Z-axis direction are set to be different from each other. r At the position of the node 4 of one region, the concave diameter surface 6 of the other region is arranged, sandwiching the two regions. Also, at the position of the concave diameter surface 6 of one region, the node 4 of the other region is arranged. Of course, the positions of the node 4 and the concave diameter surface 6 in the Z-axis direction may be set to coincide with each other.

[0059] The node 4 protrudes radially outward most at the center, and the radial protrusion length gradually decreases toward the circumferential end. r The distance (radius) from the outer diameter of node 4 is r l In this case, the radius r l The distance between the center of the rod 1 and the center of the rod 1 is the longest, and corresponds to the outermost diameter of the rod 1. r From the outermost part to the radius (r lmax The ridge line 12 of the node portion 4 is located inside an imaginary circle C (FIG. 1(d)) defined as the center of the circumferential direction of the axial ... That is, the radius r lmax is the radius r of node 4 l In relation to r lmax ≧r l and the radius r of the reduced diameter surface 2 satisfies the relationship s In relation to r lmax ≧r s Satisfy the relationship.

[0060] The connection between the node portion 4 and the reduced diameter surface 2 may be made, for example, by setting a ridge line 12 in the shape of a curve 13a at the circumferential end of the node portion 4 as shown in Figure 2(a), or by setting a ridge line 12 in the shape of a straight line 13b at the circumferential end of the node portion 4 as shown in Figure 2(b).

[0061] 3 shows other shapes of the node portion 4, where (a) is a front view, (b) is a side view, and (c) is a BB cross-sectional view of (a). The node portion 4 may be set so that the radial protrusion length at the circumferential end is approximately zero as shown in Fig. 3(c). In this case, the node portion 4 is set so that the protrusion length gradually decreases at an approximately constant rate.

[0062] Of course, the protruding length of the node portion 4 is not limited to a shape that gradually reduces along the circumferential direction, but may be a substantially constant shape in a predetermined region from the center to the circumferential end, but the ridge line 12 at the circumferential end is set to the above-mentioned curve 13a shape or straight line 13b shape and connected to the reduced diameter surface 2.

[0063] The tip end 10 of the node 4 is a circumferential end portion, and the four surfaces 14a to 14d are arranged in a direction perpendicular to the axis C. r Alternatively, the node 4 may have a generally triangular pyramidal shape having a three-dimensionally curved surface that is smaller than a curved, slender triangular pyramidal spatial region surrounded by imaginary extension planes extending in the direction of rotation about the center 14a. That is, both circumferential end portions of the node 4 may have a three-dimensionally curved surface whose protruding length in a direction perpendicular to the Z axis gradually decreases so as to be located radially inward of the surfaces 14a to 14d. Furthermore, this three-dimensionally curved surface may have a generally triangular pyramidal shape, but it may also have a curved surface shape. Furthermore, the node 4 may have a shape such that both end portions are not connected to the reduced diameter surface 2, i.e., have a length that allows them to be separated from the reduced diameter surface 2 in the circumferential direction.

[0064] 4 shows other examples of the shape of the node 4, where (a) is a perspective view, (b) is a plan view, and (c) is a front view. The node 4 has a three-dimensional curved surface whose protruding height in the direction perpendicular to the Z axis gradually decreases, and may have a boundary portion 151 between the node locking portion 150 in the central portion in the circumferential direction shown in FIG. 4 and the tip portion 152. The node 4 is also set to a shape in which the protruding height in the radial direction is greatest at the central portion and gradually decreases toward the tip portion 152, approaching approximately zero at the point closest to the reduced diameter surface 2.

[0065] Specifically, the node 4 has a shape that slopes in a generally mountain-like shape along the circumferential direction so that the protruding height gradually decreases from the center of the node locking portion 150 toward the tip 152, and the slope from the boundary portion 151 toward the tip 152 is steeper than the slope of the node locking portion 150. Furthermore, the node locking portion 150 engages with a recessed portion 26 (described later) in the Z-axis direction, and the reduction in the protruding height is set to be more gradual than that of the tip 152 in order to maintain the shear strength of the node 4.

[0066] As described above, by forming the node 4 in a shape having four faces 14a to 14d, or in a shape having the node engaging portion 150 and tip portion 152 shown in Figure 4, it is possible to improve adhesion to concrete compared to a rod-shaped body not having this configuration, and it is also possible to easily screw the node 4 into the joint structure 20 described later.

[0067] Furthermore, the protruding height of the node 4 may be increased to improve the pull-out strength when embedded in concrete. However, if the protruding height of the node 4 is increased, the node 4 may extend up to the reduced diameter surface 2, or may protrude radially outward beyond the reduced diameter surface 2 at a position adjacent to the reduced diameter surface 2. Therefore, processing such as cutting the node 4 is required to form the reduced diameter surface 2. In contrast, with the node 4 shaped as shown in FIG. 4, the gradient of the slope is made different between the node engaging portion 150 between the boundary portion 151 and the tip portion 152, thereby improving mass productivity while maintaining pull-out strength.

[0068] Therefore, if the rod-shaped body 1 has a node portion 4 with a node locking portion 150 and a tip portion 152, it is possible to continue to form the intended shape with high precision when mass-producing the rod-shaped body 1. Furthermore, since the node portion 4 has a tip portion 10 (152), it can be easily fitted into the recessed portion 26 of the joint structure 20 described below, thereby improving connectability.

[0069] [Joint structure configuration] Next, we will explain the joint structure 20. The joint structure 20 is not limited to a joint that connects two rod-shaped bodies 1, but is a concept that includes a fixing nut fixed to the end of a rebar-like rod-shaped body 1, a shelf bracket fixed midway through the rod-shaped body 1, and the like, and has an inner peripheral shape that can surround the rod-shaped body 1, with both ends open by insertion holes 21 that pass through in the axial direction.

[0070] 5 shows a joint structure 20 of this embodiment, where (a) is a perspective view, (b) is a plan view, (c) is an AA cross-sectional view of (b), and (d) is a BB cross-sectional view of (c). The joint structure 20 has an inner peripheral surface 23 that surrounds the rod-shaped body 1. The inner peripheral surface 23 has an axial center C of the joint structure 20. c The large diameter surfaces 22 are arranged at positions facing each other across the axis C, and the engaging protrusions 24 and recesses 26 are arranged adjacent to the large diameter surfaces 22 in the circumferential direction. c The insertion hole 21 has a substantially circular shape with the center at the center, and the insertion hole 21 has a substantially elliptical shape with the major axis in the direction of the large diameter surface arranged at the opposite position and the minor axis in the direction of the engaging protrusion 24 arranged at the opposite position. As will be described in detail later, when viewed in the axial direction, at both ends in the major axis direction, round shapes of different shapes are formed on the engaging rotation direction side and the counter-engagement rotation direction side with the reference line as the boundary, and at both ends in the minor axis direction, two substantially straight lines are formed. In this embodiment, the outer peripheral shape of the joint structure 20 is described as being approximately circular, but is not limited to this. For example, it may be approximately elliptical or approximately polygonal. Furthermore, as will be described later, when an expansion and contraction mechanism is provided in the joint structure, an approximately bellows shape, slits, or the like will be formed in part of the outer peripheral shape, such as an approximately circular shape.

[0071] Here, the shape of the rod-shaped body 1 when viewed in the axial direction is also approximately elliptical, and by aligning the long and short diameter directions of this elliptical shape with the long and short diameter directions of the insertion hole 21 which is approximately elliptical, the joint structure 20 can be inserted into the rod-shaped body 1. The length of the minimum inner diameter in the minor axis direction of the insertion hole 21 of the joint structure 20 is set to be smaller than the length of the diameter at the outermost diameter part in the major axis direction of the rod-shaped body 1. Therefore, the joint structure 20 cannot be inserted into the rod-shaped body 1 in a direction in which the major axis direction of the approximately elliptical shape of the rod-shaped body 1 as viewed in the axial direction is aligned with the minor axis direction of the insertion hole 21 of the joint structure 20.

[0072] As shown in Figures 5(c) and 5(d), a position restricting portion 60 that restricts the insertion depth of the rod-shaped body 1 is disposed in the axially intermediate portion of the inner peripheral surface 23 of the joint structure 20. The position restricting portion 60 protrudes radially inward from the inner peripheral surface 23 and extends circumferentially. The position restricting portion 60 is set to protrude radially inward to an extent that it can engage with the node portion 4 and / or the insertion side end face of the rod-shaped body 1, at least in the insertion direction of the rod-shaped body 1. This restricts the insertion depth of the rod-shaped body 1 inserted into the joint structure 20. A pair of rod-shaped bodies are connected in the axial direction with the axially intermediate portion of this joint structure 20 as a boundary. The position restriction portion 60 does not necessarily have to be provided continuously in the circumferential direction on the inner peripheral surface 23, but may be disposed intermittently. The position restriction portion 60 may also be disposed in a non-helical shape or in a helical shape. As will be described in detail later, the position regulating portion 60 may be provided with a guide structure 60a that guides the node portion 4 of the rod-shaped body 1 into the recessed portion 26 of the joint structure 20. This makes it possible to automatically guide the node portion 4 so that it matches the axial position of the recessed portion 26. If the position restricting portion 60 is not provided, for example, the confirmation hole 58 may be used as an intermediate position indicating means, which will be described later. By providing the intermediate position indicating means, the position of the rod-shaped body 1 can be visually confirmed, and the position of the rod-shaped body relative to the axial intermediate portion of the joint structure can be grasped simultaneously and easily.

[0073] In this embodiment, a guide space is provided in the radial direction between the joint structure 20 and the rod-shaped body 1. As shown in FIG. 13 , the joint structure 20 inserts the rod-shaped body 1 into the insertion hole 21, and then rotates the rod-shaped body 1 in the circumferential direction relative to the rod-shaped body 1 to fix the rod-shaped body 1. If the guide space were not provided, when the rod-shaped body 1 is inserted into the insertion hole 21 of the joint structure 20, the node 4 of the rod-shaped body 1 may interfere with the inner circumferential surface 23 of the joint structure 20 (see FIG. 5( a)), causing the rod-shaped body 1 to become stuck. This may prevent the rod-shaped body 1 from being smoothly inserted into the joint structure 20. Furthermore, even after the rod-shaped body 1 is inserted into the insertion hole 21, when the joint structure 20 rotates in the circumferential direction relative to the rod-shaped body 1, the node 4 of the rod-shaped body 1 may interfere with the inner circumferential surface 23 of the joint structure 20 (see FIG. 5( a)), causing the rod-shaped body 1 to become stuck. Therefore, there is a risk that the joint structure 20 may not be able to rotate smoothly in the circumferential direction relative to the rod-shaped body 1. The joint structure 20 according to this embodiment solves this problem, and will be described in detail below.

[0074] Figure 6 is a plan view showing the state in which the rod-shaped body 1 is inserted into the joint structure 20, where (a) shows the state in which the rod-shaped body 1 is inserted into the insertion hole 21 of the joint structure 20 (i.e., the state in Figure 13(a) described below), and (b) and (c) show the state in which the rod-shaped body 1 is rotated relative to the joint structure 20 in a predetermined direction. 6(a), the state in which the rod-shaped body 1 is inserted into the joint structure 20 refers to a state in which the end face of the rod-shaped body 1 on the insertion direction side abuts against the position regulating portion 60.

[0075] The imaginary circle indicated by the dashed line in Fig. 6 is a trajectory drawn by the rotation of the rod-shaped body 1 inserted into the joint structure 20, and indicates the base circle of the rod-shaped body 1. This base circle is located at the axis C of the rod-shaped body 1. r The orbit is drawn by the circumferential center of the concave surface 6 of the rod-shaped body 1, with the center at the center. Note that when the rod-shaped body 1 is inserted to a fixed position or to the deepest part of the joint structure 20, the axis C of the joint structure 20 is c and the axis C of the rod-shaped body 1 r are roughly consistent.

[0076] The dashed line shown in FIG. 6(a) is a line connecting the approximate center of the large diameter surface 22 and the axis C of the joint structure 20 in a plan view.c It is a virtual line passing through. When this virtual line is used as a reference line, the rotation direction when the rod-shaped body 1 is rotated in the engagement direction, i.e., clockwise, relative to the boundary, with the reference line as the boundary, is called the engagement rotation direction, and the direction when the rod-shaped body 1 is rotated in the anti-engagement direction, i.e., counterclockwise, relative to the boundary, is called the anti-engagement rotation direction. Note that in this embodiment, the engagement direction is described as the clockwise direction and the anti-engagement direction is described as the counterclockwise direction, but this is not limited to this. For example, the engagement direction may be the counterclockwise direction and the anti-engagement direction may be the clockwise direction.

[0077] The outer peripheral shape of the joint structure 20 shown in FIG. 6(a) is c The insertion hole 21 has a substantially circular shape with the center at the reference line, and the insertion hole 21 has a substantially elliptical shape with the major axis in the direction of the large diameter surface arranged at the opposite position and the minor axis in the direction of the engaging convex portion 24 (or concave portion 26) arranged at the opposite position. At both ends in the major axis direction, rounded portions with different shapes are formed on the engaging rotation direction side and the counter-engagement rotation direction side with the reference line as the boundary, and at both ends in the minor axis direction, two substantially straight lines are formed.

[0078] The large diameter surface 22 is set so as to be located radially outward of the outermost diameter portion of the node portion 4 when the rod-shaped body 1 is inserted. That is, the large diameter surface 22 is set to have a radius larger than that of the node portion 4 so as to be in a substantially non-contact state with the node portion 4. The radius r d is the axis C c The distances from the axis C are not limited to being approximately equal, and as long as the joint 4 is not in contact with the axis C, c The distance from the center of gravity may be set to vary along the circumferential direction.

[0079] The engaging protrusions 24 and / or recesses 26 adjacent to the large diameter surface 22 in the circumferential direction are set so as to be positioned radially outward of the reduced diameter surface 2 when the rod-shaped body 1 is inserted. That is, the diameters of the engaging protrusions 24 and / or recesses 26 are set to the ends so that they are in a substantially non-contact state with the reduced diameter surface 2. As described above, both ends of the joint structure 20 in the minor diameter direction are formed in a substantially linear shape when viewed in the axial direction. cThe distance from the center to the end gradually decreases toward the circumferential center and is shortest at the circumferential center.

[0080] The guide space portion will now be described. The guide space portion is defined by a small guide space S formed in the radial and circumferential directions on each of the axially opposing surfaces between the large diameter surface 22 of the joint structure 20 and the outermost diameter portion of the node portion 4 of the rod-shaped body 1. The guide space S allows smooth relative movement of the rod-shaped body 1 in the radial and circumferential directions. Naturally, the size of the guide space S varies with the relative rotation between the rod-shaped body 1 and the joint structure 20.

[0081] The circumferential shape of the large diameter surface 22 as viewed in the axial direction is set appropriately. In this embodiment, the circumferential shape of the large diameter surface 22 differs between the engaging rotation direction side and the counter-engagement rotation direction side with respect to the reference line, as shown in Figures 6(a) and 25. 6(a) and 25. On the engagement rotation direction side, the diameter of the large diameter surface 22 extends from the boundary toward the concave portion 26 (and the engagement convex portion 24, not shown) from the approximate center of the large diameter surface 22 toward the axis C c That is, in the range along the rotation direction from the boundary to the recessed portion 26, an arc shape (first arc shape) that has a substantially constant radius of curvature and is substantially a perfect circle when viewed in the axial direction is formed. The radius of this first arc shape is defined as r d1 and the radius of the outermost part of the node 4 of the rod-shaped body 1 is r lmax In this case, r d1 >r lmax Therefore, a guide space S is defined between the large diameter surface 22 of the joint structure 20 and the outermost diameter portion of the node portion 4 of the rod-shaped body 1, allowing smooth relative movement of the rod-shaped body 1 in the radial and circumferential directions.

[0082] On the other hand, on the counter-engagement rotation direction side, the diameter of the large diameter surface 22 extends from the boundary toward the engagement protrusion 24 (and the recess 26, not shown) to the middle thereof, from the approximate center of the large diameter surface 22 to the axis C. cThat is, in the range along the rotational direction from the boundary to the middle, an arc shape (second arc shape) is formed that is approximately a perfect circle in the axial direction and has a radius of curvature that is the same as or approximately the same as the first arc shape formed on the engagement rotational direction side. The radius r of this second arc shape d2 In this case, the radius r at the outermost part of the node 4 lmax The relationship between lmax <r d2 This becomes: Therefore, in the joint structure 20, a guide space S is defined between the large diameter surface 22 on which the second arc shape is formed and the outermost diameter portion of the node portion 4 in the rod-shaped body 1, allowing smooth relative movement of the rod-shaped body 1 in the radial and circumferential directions.

[0083] Next, the diameter of the large diameter surface 22 is formed with a circular arc shape (third circular arc shape) that has a radius of curvature smaller than that of the second circular arc shape in a range along the rotation direction in the middle of this range. The radius of this third circular arc shape is defined as r d3 Then, the radius of the second arc shape is r d2 Here, the radius r of the third arc shape is d3 is set to a size that can interfere with the outermost part of the node 4, so r d3 ≦r lmax <r d2 It fulfills the relationship. Therefore, the guide space S between the large diameter surface 22 on which the third arc shape is formed in the joint structure 20 and the outermost diameter portion of the node portion 4 in the rod-shaped body 1 shrinks and disappears, thereby restricting the relative movement of the rod-shaped body 1 in the radial and circumferential directions.

[0084] The diameter of the large diameter surface 22 increases from the middle to the engaging protrusion 24 with a radius r d The length of the shaft is gradually reduced, and the shaft becomes approximately linear when viewed in the axial direction. c The distance from the large diameter surface 22 formed in a substantially linear shape is r ds In this case, r ds ≦r d3 Satisfy the relationship.

[0085] In this embodiment, the large diameter surface 22 formed as a third arc shape on the joint structure 20 in the axial direction may interfere with the outermost diameter portion of the node portion 4, but this is not limited to this. For example, the second arc shape formed on the joint structure 20 may interfere with the outermost diameter portion of the node portion 4. In this case, the large diameter surface 22 may be spaced apart from the axis C by a distance from the approximate center of the large diameter surface 22 to the axis C. c Distance to r d0 In other words, the radius of the large diameter surface 22 at the boundary is r d0 Then, r ds ≦r d3 <r d2 ≦r lmax <r d0 The following relationship is satisfied. Therefore, the guide space S between the large diameter surface 22 on which the second arc shape is formed in the joint structure 20 and the outermost diameter portion of the node portion 4 in the rod-shaped body 1 shrinks and disappears, thereby restricting the relative movement of the rod-shaped body 1 in the radial and circumferential directions.

[0086] In this case, the rod-shaped body 1 interferes with the joint structure 20 at the second arc shape, and therefore, further relative rotation toward the engaging protrusion 24 is restricted. Therefore, it is not necessarily required to form the third arc shape and / or a substantially linear shape on the large diameter surface 22.

[0087] Also, the large diameter surface 22 formed in a substantially linear shape on the joint structure 20 when viewed in the axial direction may be configured to interfere with the outermost diameter portion of the node portion 4. In this case, r ds ≦r lmax <r d3 <r d2 The following relationship is satisfied.

[0088] In this case, it is not necessary to form the second and third arc shapes on the large diameter surface 22, but it is sufficient that the outermost diameter portions of the node portions 4 of the rod-shaped body 1 can rotate relatively to the extent that they can interfere with the large diameter surface 20, which is formed in a substantially linear shape. In other words, within the circumferential range in which relative rotation is possible, a guide space S is defined between the large diameter surface 22 and a virtual arc formed by the path traced by the outermost diameter portions of the node portions 4 of the rod-shaped body 1, as viewed in the axial direction. As long as the guide space S can be defined, the diameter of the large diameter surface 22 does not necessarily have to be arc-shaped as viewed in the axial direction.

[0089] In this embodiment, it has been described that the third arc shape is formed on the large diameter surface 22 in the counter-engagement rotation direction, from the boundary toward the engaging protrusion 24, approximately halfway therebetween, and the outermost diameter portion of the node 4 of the rod-shaped body 1 interferes with the large diameter surface 22. However, the position where the third arc shape is formed is not limited to approximately the middle. For example, the position where the third arc shape is formed may be within a range from the boundary shown in Fig. 6(a) to just before the rod-shaped body 1 reaches the engaging convex portion 24 (and concave portion 26, not shown) on the counter-engagement rotation direction side. Within this range, the outermost portion of the node portion 4 of the rod-shaped body 1 and the large diameter surface 22 of the joint structure 20 interfere with each other.

[0090] As described above, the outer peripheral shape of the joint structure 20 in the axial view is c The inner circumferential shape of the large diameter surface 22 is a substantially circular shape with a center of d When the radius r of the inner circumferential shape of the large diameter surface 22 becomes smaller, the thickness of the joint structure 20 becomes thicker. d As the thickness of the joint structure 20 increases, the thickness of the joint structure 20 decreases. For example, the thickness t0 of the joint structure 20 shown in FIG. 6(c) is a radius r d The position where the radius r d0 Indicates the wall thickness at the position of In addition, the thickness t1 is d0 2 indicates the wall thickness at a position where a radius smaller than the above is set (that is, the position where the large diameter surface 22 and the node portion 4 of the rod-shaped body 1 abut against each other). The wall thickness t0 and the wall thickness t1 satisfy the relationship t0 < t1.

[0091] Also, as shown in FIG. 25, the first arc shape, the second arc shape, the third arc shape, and the substantially straight line shape are formed so as to be spaced apart and opposed to the large-diameter surface 22 at a point-symmetrical position with respect to the axis C. c Note that the arc shapes and the substantially straight line shapes formed at the point-symmetrical positions do not necessarily have to be substantially the same shape as the corresponding shapes, and may be substantially similar shapes.

[0092] To sum up, when the rod-shaped body 1 rotates in the engagement rotation direction, the presence of the guide space S causes it to be non-interfering with respect to the large-diameter surface 22. Also, when the rod-shaped body 1 rotates in the reverse engagement rotation direction, the guide space S shrinks and disappears, so as a result, it interferes with the large-diameter surface 22 and the rotation is restricted.

[0093] Here, in order to smoothly relatively rotate the joint structure 20 with respect to the rod-shaped body 1 by a predetermined angle in a predetermined direction, it is also possible to provide a guide space portion. That is, the guide space portion allows the rotation of the rod-shaped body 1 by a predetermined angle as a relative movement in the circumferential direction of the rod-shaped body 1. The guide space portion does not have to be formed over the entire circumferential direction of the large-diameter surface 22, and it may be formed at least in a part of the circumferential direction of the large-diameter surface 22. That is, when the joint structure 20 is smoothly relatively rotated with respect to the rod-shaped body 1 by a predetermined angle in a predetermined direction, instead of over the entire circumferential direction of the large-diameter surface 22, at least in the circumferential range of the large-diameter portion 22 corresponding to the arc of the predetermined angle described by the outermost diameter portion of the joint portion 4 in the rod-shaped body 1, a guide space S may be formed between the large-diameter portion 22 and the outermost diameter portion.

[0094] Note that the portion of the rod-shaped body 1 that abuts against the large-diameter surface 22 may be the outer diameter portion of the joint portion 4, and does not necessarily have to be the outermost diameter portion. FIG. 6(b) shows a state in which the outer diameter portion of the joint portion 4 of the rod-shaped body 1 abuts against the large-diameter surface 22 when the rod-shaped body 1 is relatively rotated by an angle α in the engagement rotation direction (right direction) with respect to the joint structure 20. In this case, the outer diameter portion of the node portion 4 located on the right side of the reference line indicated by the dashed dotted line in FIG. 6(a) comes into contact with the large diameter surface 22. The guide space S is formed in the circumferential range from the reference line to the position where the outer diameter portion of the node portion 4 and the large diameter surface 22 abut against each other. Specifically, the length of the diameter of the joint structure 20 at any position in the circumferential range (radius r d ) is the axis C of the rod-shaped body 1 r The length from the outer diameter of the node 4 (radius r l ) is set to be equal to or slightly shorter than the Therefore, when viewed from above in the axial direction, the circumferential shape of the insertion hole 21 of the joint structure 20 is such that, in the range along the rotation direction on the engagement rotation direction side, the radius r l r set to be equal to or slightly shorter than d The arc shape has a radius of curvature of As a result, the outer diameter portion of the node portion 4 of the rod-shaped body 1 comes into contact with the large diameter surface 22 of the joint structure 20. d The length of the rod-shaped body 1 can be set so that the node 4 of the rod-shaped body 1 can enter the recess 26 of the joint structure 20 and can be rotated by a torque large enough to elastically deform the node 4 and / or the large diameter surface 22 of the rod-shaped body 1.

[0095] In the above example, the engagement rotation direction is the rightward relative rotation, but the direction of relative rotation may be either rightward or leftward. Furthermore, relative rotation in both directions may be permitted. When relative rotation in both directions is permitted, different angles may be set for smooth relative rotation in the rightward and leftward directions. For example, the guide space portion can set a predetermined angle for allowing rotation in one direction as a relative movement in the circumferential direction of the rod-shaped body 1 to be larger than a predetermined angle for allowing rotation in the other direction. Furthermore, the angle may be set to allow smooth relative rotation not only in the engaging rotation direction but also in the counter-engagement rotation direction. For example, Fig. 6(c) shows a state in which the outer diameter portion of the node portion 4 of the rod-shaped body 1 abuts against the large diameter surface 22 when the rod-shaped body 1 is rotated by an angle β in the counter-engagement rotation direction (leftward) with respect to the joint structure 20. In this case, the outer diameter portion of the node portion 4 located on the left side of the reference line indicated by the dashed line in FIG. 6(a) comes into contact with the large diameter surface 22. The guide space S is formed in the circumferential range from the reference line to the position where the outer diameter portion and the large diameter surface 22 abut against each other. Specifically, the length of the diameter of the joint structure 20 at any position in the circumferential range (radius r d ) is the axis C of the rod-shaped body 1 r The length from the outer diameter of the node 4 (radius r l ) is set shorter. Therefore, when viewed from above in the axial direction, the circumferential shape of the joint structure 20 is such that the radius r of the node portion 4 of the rod-shaped body 1 is smaller than the radius r of the joint portion 4 of the rod-shaped body 1 in at least a part of the range along the rotation direction on the counter-engagement rotation direction side. l A shorter radius r d The arc shape has a radius of curvature of In addition, when viewed in the axial direction, the radius r d Where the thickness of the joint structure 20 is reduced, the thickness of the joint structure 20 is increased. As shown in FIG. 6(b), when the large diameter surface 22 and the outer diameter portion of the node portion 4 are in contact with each other by the relative rotation in the engagement rotation direction, the length in the thickness direction of the joint structure 20 at the contact point is defined as t1, and the length of the radius to the outer diameter portion at the contact point is defined as r. l As shown in FIG. 6(c), when the large diameter surface 22 and the outer diameter portion of the node portion 4 come into contact with each other by rotating the large diameter surface 22 in the counter-engagement rotation direction, the length of the joint structure 20 in the thickness direction at the contact point is t2, and the radius of the joint structure 20 to the outer diameter portion at the contact point is r2. l The sum of thickness t1 and radius r l The sum of these satisfies the approximately identical relationship. Furthermore, in the anti-engagement rotation direction, further relative rotation toward the engaging convex portion 24 (and the concave portion 26, not shown) is not permitted, and it can be said that the outer diameter portion of the rod-shaped body 1 and the large diameter surface 22 of the joint structure 20 are in interference with each other.

[0096] Returning to Fig. 5, the engaging protrusions 24 and the recessed portions 26 will be described. The engaging protrusions 24 protrude radially inward from the large diameter surface 22, extend in the circumferential direction, and are arranged in a plurality of rows in the axial direction. As shown in Fig. 6(a), the engaging protrusions 24 are aligned with the axis C so as to be positioned radially outward from the reduced diameter surface 2 when the rod-shaped body 1 is inserted. c The distance from is set.

[0097] Returning to FIG. 5, the recesses 26 are depressions having a recessed shape relative to the engaging protrusions 24, and are arranged alternately with the engaging protrusions 24 in the axial direction. The depth of the recesses 26 is set so that the bottoms are arranged at least radially outward of the node portions 4 at predetermined relative positions. That is, the recesses 26 are arranged at positions corresponding to the axis C. c The depth may be set so that the distances from the large diameter surface 22 and the large diameter surface 22 are approximately equal, and the recessed portion 26 may be connected to the large diameter surface 22 to form a substantially continuous surface. c The depth may be set so that the distance from the target point is longer.

[0098] The recessed portion 26 has a symmetrical shape with respect to an axis of symmetry parallel to the axial direction when viewed in the radial direction. That is, as shown in FIG. 7( a), the recessed portion 26 has closed ends (29, 31) at both circumferential ends and a shape similar to the shape of the node portion 4 when viewed in the radial direction. The closed end 31, which is closed at one circumferential end (the left end in FIG. 7( a)), gradually widens in the axial direction toward the other end, reaching its widest point at approximately the middle. The width gradually narrows from this approximately middle position toward the other end (the right end in FIG. 7( a)), and the other end becomes the closed end 29 that restricts the circumferential displacement of the node portion 4. The closed end may be formed by providing a wall-shaped stopper that protrudes radially from the bottom surface of the recessed portion 26 at the other end. The radial protrusion length of the stopper is set so as to restrict at least the circumferential displacement of the node portion 4. The recessed portion 26 is not limited to a symmetrical shape, and may also be asymmetric. For example, as shown in FIG. 9, one circumferential end of the recessed portion 26 may be an open end with an increased width, and the other end may be a closed end.

[0099] In addition, the engaging protrusions 24 and the recessed portions 26 are arranged in two regions facing each other across the axis so as to correspond to the node portions 4 and the concave diameter surfaces 6 of the rod-shaped body 1, and the engaging protrusions 24 in one region and the engaging protrusions 24 in the other region are set so that their axial positions are different from each other. Fig. 5(c) is a cross-sectional view showing the joint structure 20, illustrating the positional relationship between the engaging protrusions 24 and the recessed portions 26 in two opposing regions spaced apart in the radial direction. As shown in Fig. 5(c), the engaging protrusions 24 are provided in one region located on the left side, while the recessed portions 26 are provided in the other region located on the right side, and the engaging protrusions 24 are provided in the other region, while the recessed portions 26 are provided in one region. Therefore, similar to the nodes 4 and recessed surfaces 6 of the rod-shaped body 1, by making the engaging protrusions 24 and recessed portions 26 staggered, the nodes 4 of the rod-shaped body 1 can be fitted into each recessed portion 26.

[0100] In addition, the rod-shaped body 1 is centered at the axis C. r In the case of a shape in which the axial positions of the node portion 4 and the concave diameter surface 6 are aligned in two opposing regions sandwiching the axial position, the axial positions of the engaging protrusion 24 and the concave portion 26 are aligned.

[0101] 7A and 7B are schematic diagrams illustrating the entry of the node portion 4 into the recessed portion 26, with (a) illustrating the position of the node portion 4 before it enters the recessed portion 26 (i.e., the state before the joint structure 20 and the rod-shaped body 1 are fixed), and (b) illustrating the position when it is fitted into the recessed portion 26 (i.e., the state when the joint structure 20 and the rod-shaped body 1 are fixed). Note that FIG. 7 illustrates the inner peripheral surface 23 of the joint structure 20 on the front side, and since the surfaces 14a to 14d of the node portion 4 face the recessed portion 26, the rod-shaped body 1 (not shown) is positioned on the front side of the page, and the ridge line 12 and the like of the node portion 4 are illustrated by dotted lines, illustrating the state in which the surfaces 14a to 14d face the recessed portion 26 toward the back side of the page.

[0102] The joint structure 20 rotates relatively in a predetermined direction so that the node 4 shown in Fig. 7(a) enters the recessed portion 26 from the closed end 31. The joint structure 20 is also rotated relatively to a position where the node 4 shown in Fig. 7(b) fits into the recessed portion 26 and the leading end of the node 4 in the traveling direction abuts against the closed end 29 of the recessed portion 26.

[0103] When the node portion 4 enters between the engaging protrusions 24, the joint structure 20 is restricted from axial displacement relative to the rod-shaped body 1. That is, relative displacement between the joint structure 20 and the rod-shaped body 1 is restricted in both directions, that is, when the rod-shaped body 1 is pulled out or pushed in, relative to the joint structure 20. Furthermore, when the node portion 4 abuts against the closed end 29, the joint structure 20 is restricted from circumferential displacement along a predetermined rotational direction relative to the rod-shaped body 1. Therefore, the rod-shaped body 1 is connected to and fixed to the joint structure 20.

[0104] As will be described in more detail later, as shown in Figure 9(b), the node portion 4 of the rod-shaped body 1 has a pointed tip 10, and one end of the concave portion 26 of the joint structure 20 is an open end 28 with a widened shape, which prevents the engaging protrusion 24 from getting caught on the node portion 4 when the joint structure 20 is rotated, making it easier to fit the node portion 4 into the concave portion 26.

[0105] FIG. 8 shows a schematic diagram of the rod-shaped body 1 and the joint structure 20 before and after engagement, where (a) is a plan view showing the state before engagement, (b) is a plan view showing the state after engagement, (c) is a cross-sectional view in the state of (a), and (d) is a cross-sectional view in the state of (b). 8(a) and 8(c) show the state in which the rod-shaped body 1 is inserted into the joint structure 20, as described in FIG. 6(a) (i.e., the state shown in FIG. 13(a) described later). Here, as described in FIG. 6(b), when the rod-shaped body 1 is rotated rightward by an angle α, the outermost diameter portion of the rod-shaped body 1 comes into contact with the large-diameter surface 22. When the rod-shaped body 1 is further rotated rightward with a torque large enough to elastically deform the node portion 4 and / or the recessed portion 26, the node portion 4 can be set to enter the recessed portion 26. When the rod-shaped body 1 is further rotated rightward, the node portion 4 is rotated relative to the recessed portion 26 until the node portion 4 fits into the recessed portion 26 and the tip of the node portion 4 in the direction of entry comes into contact with the closed end 29 of the recessed portion 26, as shown in FIGS. 7(b) and 8(b) and 8(d). This fixes the rod-shaped body 1 and the joint structure 20 together.

[0106] Furthermore, as shown in Figure 7, as long as the engaging protrusion 24 has a surface at the circumferential end, the node portion 4 and the engaging protrusion 24 may interfere with each other, and the relative rotation of the joint structure 20 with respect to the rod-shaped body 1 may be restricted. For this reason, as shown in FIG. 9(a), one end of the recessed portion 26 (the left end in FIG. 7(a)) can be widened, that is, made into a guide shape that is greatly widened in the axial direction. Furthermore, sharpening the tip 10 of the node 4 is preferable because it allows the node 4 to fit more easily into the recessed portion 26 without getting caught. For example, as shown in FIG. 9(b), the tip 10 can be made sharp and one end of the recessed portion 26 can be provided with an open end 28 that is wider than the other end. This prevents the ends from interfering with each other, and the node 4 is automatically guided into the recessed portion 26, making it easier to fit, facilitating connection between the rod-shaped body 1 and the joint structure 20.

[0107] The joint structure 20 is connected to the rod-shaped body 1 by rotating it relative to the rod-shaped body 1, but since the open end 28 is formed in the recessed portion 26, the joint structure 20 is capable of reverse rotation. If the joint structure 20 rotates in the reverse direction, the connection between the rod-shaped body 1 and the joint structure 20 will be released. Therefore, a reverse rotation prevention structure may be provided between the rod-shaped body 1 and the joint structure 20. For example, the reverse rotation prevention structure can be formed by changing the shape of the recessed portion relative to the node portion 4. Here, Fig. 10 is a view from the radial direction showing another example of the inner peripheral shape of the joint structure 20. For example, the axial length (width) of the recessed portion 30 can be reduced on the open end 32 side, that is, the open end 32 of the recessed portion 30 can be made narrower than the middle portion to form the reverse rotation prevention structure.

[0108] In this case, the width of the open end 32 is set smaller than the maximum width (width of the circumferential center) of the node portion 4. The difference between the width of the open end 32 and the maximum width of the node portion 4 is set to an extent that allows the node portion 4 and / or the engaging protrusion 24 to elastically deform and enter the recessed portion 30.

[0109] 11A and 11B are schematic diagrams showing the entry of the node 4 into the recessed portion 30, with (a) showing the position before entry into the recessed portion 30 and (b) showing the position after engagement with the recessed portion 30. In FIG. 12, the approximate positions of the surfaces 14a and 14b located on the far side of the page are indicated by dotted lines and corresponding symbols. As shown in FIG. 11A, the surfaces 14a and 14b of the node 4 abut against the engaging protrusion 24 on the open end 32 side of the recessed portion 30. By pushing against this resistance, the surfaces 14a and 14b and / or the engaging protrusion 24 are elastically deformed, and the node 4 enters the recessed portion 30 as shown in FIG. 11B.

[0110] By fitting the node portion 4 into the recessed portion 30 in this manner, even if a torque or the like acts in the opposite direction to the rotational direction when the joint structure 20 is connected to the rod-shaped body 1, in order for the node portion 4 to come out of the recessed portion 30, it is necessary to apply a torque of a magnitude sufficient to elastically deform the surfaces 14c, 14d and / or the engaging protrusion 24, and as a result, a reverse rotation prevention structure is formed.

[0111] Furthermore, the reverse rotation prevention structure may be formed by a member separate from the rod-shaped body 1 and the joint structure 20. For example, when the rod-shaped body 1 is fixed to the joint structure 20, the reduced diameter surface 2 of the rod-shaped body 1 faces the large diameter surface 22 of the joint structure 20, and a gap is generated between the reduced diameter surface 2 and the large diameter surface 22. Therefore, as shown in FIG. 12 , the gap between the reduced diameter surface 2 and the large diameter surface 22 may be filled by a rotation prevention member 40 having a plate shape with a holed irregular outer shape and including spacer portions 42 erected around holes 44 in a direction approximately perpendicular to the plate surface.

[0112] Specifically, the rod-shaped body 1 is inserted through the hole 44 with the tip of the spacer portion 42 facing the joint structure 20, and the anti-rotation member 40 is brought into contact with or close to the end face of the joint structure 20, and the spacer portion 42 is inserted between the reduced diameter surface 2 and the large diameter surface 22 to fill the gap. As a result, even if an attempt is made to rotate the joint structure 20 so that the node portion 4 is relatively displaced in a direction to retract from the recessed portion 30, the spacer portion 42 can restrict the relative displacement of the node portion 4, i.e., the rotation of the joint structure 20 can be restricted.

[0113] When the anti-rotation member 40 is provided, for example, a nut may be threaded onto the rod-shaped body 1 at a position facing the joint structure 20 across the anti-rotation member 40 to prevent the spacer portion 42 from coming off. The spacer portion 42 may be formed in a wedge shape that is thinner from the base end to the tip end, or the outer surface of the erected surface may be made uneven to improve engagement. In this case, a corresponding uneven shape may be formed on the large-diameter surface of the joint structure 20. In addition, such anti-rotation members can be applied to conventional reinforcing bars and joints in which an axial gap occurs between the reinforcing bar and the joint when the reinforcing bar and the joint are screwed together.

[0114] In addition, the anti-rotation member 40 may be configured so that its irregularly shaped outer portion can be fitted into a receiving portion that can receive an irregular shape and is provided at the axial end of the joint structure 20, thereby further preventing relative rotation of the anti-rotation member 40 with respect to the joint structure 20.

[0115] Furthermore, the joint structure 20 has a shape in which the concave portion 26 has an open end 28 so that the node portion 4 can be displaced circumferentially and enter the concave portion 26, but the shape of the joint structure may also be set so that the node portion 4 fits into the concave portion 26 from the radial direction.

[0116] [Joint structure and rod-shaped body connection procedure] Here, the connection of the two rod-shaped bodies 1a and 1b by the joint structure 20 will be described with reference to FIG. First, as shown in FIG. 13(a), the rod-shaped body 1a is inserted into the insertion hole 21 at one end of the joint structure 20 in the axial direction, and the joint structure 20 is displaced toward the rod-shaped body 1a. When inserting the joint structure 20 into the rod-shaped body 1a, as shown in FIG. 6(a), the engaging convex portion 24 and the concave portion 26 of the joint structure 20 are aligned to face the reduced diameter surface 2 of the rod-shaped body 1a, and the large diameter surface 22 of the joint structure 20 is aligned to face the node portion 4 of the rod-shaped body 1a. In this state, the joint structure 20 can be inserted along the axial direction without interfering with the rod-shaped body 1a. That is, because the reduced diameter surface 2 of the rod-shaped body 1a is located radially inward of the engaging convex portion 24 of the joint structure 20 and the node portion 4 of the rod-shaped body 1a is located radially inward of the large diameter surface 22 of the joint structure 20, the rod-shaped body 1a can be inserted without interfering with the joint structure 20 and can be displaced in the axial direction. The rod-shaped body can be displaced up to the position regulating portion 60 shown in FIGS. 5(c) and 5(d).

[0117] Next, as shown in FIG. 13( b ), the joint structure 20 is rotated relative to the rod-shaped body 1 a in the circumferential direction, and the rod-shaped body 1 a is fixed to the joint structure 20 . More specifically, after the joint structure 20 is inserted into the rod-shaped body 1a, the engaging convex portions 24 and concave portions 26 on the inner circumferential surface 23 of the joint structure 20 face the reduced diameter surface 2 of the rod-shaped body 1a, and the large diameter surface 22 faces the node portions 4 of the rod-shaped body 1a (FIG. 6(a)). In this state, when the joint structure 20 is rotated counterclockwise as indicated by the arrow in FIG. 13(b), the above-mentioned guide space S allows the joint structure 20 to smoothly move relative to the rod-shaped body 1a in the circumferential direction to a position where the outermost diameter portion of the rod-shaped body 1a abuts against the large diameter surface 22. Here, in order to further rotate the joint structure 20 counterclockwise, the joint structure 20 is rotated with a torque large enough to elastically deform the node portions 4 and / or the concave portions 26. As a result, the node 4 fits into the recessed portion 26 and moves relative to the recessed portion 26 until the tip of the node 4 in the direction of entry abuts the closed end 29 of the recessed portion 26, thereby fixing the joint structure 20 and the rod-shaped body 1a (Figures 7(b) and 8(b)).

[0118] Next, the insertion hole 21 on the other end side of the joint structure 20 is brought adjacent to the end face of the rod-shaped body 1b, the engaging convex portion 24 and concave portion 26 of the joint structure 20 are aligned to a position facing the reduced diameter surface 2 of the rod-shaped body 1b, and the large diameter surface 22 of the joint structure 20 is aligned to a position facing the node portion 4 of the rod-shaped body 1b (Figure 6(a)). Then, the joint structure 20 is displaced toward the rod-shaped body 1b so as to insert the rod-shaped body 1b into the other end side in the axial direction of the joint structure 20. As a result, as shown in Fig. 13(c), the rod-shaped body 1b can be inserted into the joint structure 20 by relatively displacing it in the opposite direction to the insertion of the rod-shaped body 1a.

[0119] Finally, as shown in FIG. 13(d), the joint structure 20 can be rotated clockwise relative to the rod-shaped bodies 1a and 1b as indicated by the arrows, thereby connecting the rod-shaped bodies 1a and 1b via the joint structure 20.

[0120] [First Modification of First Embodiment] As a modification of this embodiment, the position regulating portion 60 may be provided with a guide structure 60a that guides the node portion 4 of the rod-shaped body 1 into the recessed portion 26 of the joint structure 20. This makes it possible to automatically guide the node portion 4 so that it matches the axial position of the recessed portion 26. The nodes 4 of the rod-shaped body 1 are formed with a pitch and phase relationship. However, when the rod-shaped body 1 is cut in the axial direction for length adjustment, the cut is made at a position that does not take into account the pitch and phase relationship. Therefore, it is necessary to adjust the axial position relative to the joint structure. The guide structure solves this problem and will be described in detail below.

[0121] As shown in FIGS. 5(c) and 5(d), the guide structure 60a is aligned with the axis C of the joint structure 20. c The recessed portions 26 are formed in the axially middle portions of both of the opposing large-diameter surfaces 22 in the shape of arcs forming part of a spiral, and protrude radially inward from the large-diameter surfaces 22, extending circumferentially to the position of the recessed portions 26. As a result, when the rod-shaped body 1 is rotated, the nodes 4 of the rod-shaped body 1 are automatically guided from the open ends 28 into the recessed portions 26, following the arcs forming part of the spiral. The guide structure 60a is set such that the radially inward protrusion of the strip can lock the node 4 of the rod-shaped body 1 and / or the insertion-side end face of the rod-shaped body 1, at least in the insertion direction of the rod-shaped body 1. For example, when locking the node 4, the protrusion is set to approximately the height of the node 4. This makes it possible to restrict the insertion depth of the rod-shaped body 1 inserted into the joint structure 20 and to guide the node 4 into the recess 26.

[0122] 14A and 14B are schematic views of the entry of the node 4 into the recessed portion 26, with (a) showing the node 4 being guided by the guide structure 60a and (b) showing the state when the node 4 is fitted into the recessed portion 26. Note that FIG. 14 shows the inner peripheral surface 23 of the joint structure 20 on the front side, and since the surfaces 14a to 14d of the node 4 face the recessed portion 26, the rod-shaped body 1 (not shown) is positioned on the front side of the page, and the ridge line 12 of the node 4 is shown by a dotted line, showing the state in which the surfaces 14a to 14d face the recessed portion 26 toward the back side of the page.

[0123] 14(a), the guide structure 60a is formed so that one end of the spiral strip is adjacent to the lower recessed portion 26a closer to the insertion direction of the rod-shaped body 1. As a result, when the joint structure 20 is rotated relative to the rod-shaped body 1, the surface 14b closer to the insertion direction of the node portion 4 of the rod-shaped body 1 is automatically guided from the open end 28 to the lower recessed portion 26a while abutting against the guide structure 60a. 14(b), the node 4 is fitted into the recess 26 and rotated relatively to a position where the leading end of the node 4 in the moving direction abuts against the closed end 29 of the recess 26.

[0124] The guide structure 60a may be a continuous structure, or multiple guide structures may be arranged in a continuous, circumferential direction. The length, number, and spacing of the guide structures may be set as appropriate. The guide structure may be a convex stripe formed in either a right-handed or left-handed spiral shape.

[0125] 15, the lower recessed portion 26a may not be formed, and a guide structure 60b may be provided instead of the lower recessed portion 26a. In this case, when the joint structure 20 is rotated relative to the rod-shaped body 1, the node portion 4 of the rod-shaped body 1 will be guided by the guide structure 60b and will fit into the recess formed by the upper recessed portion 26b and the guide structure 60b. 15(a) from the large diameter surface 22 on which the guide structure 60b is formed to the circumferentially adjacent engaging protrusion 24 and / or recess 26, protruding radially inward while tilting slightly upward and to the right in the direction shown in FIG. 15(a). In other words, the guide structure 60b can be formed not only on the large diameter surface 22 but also on the engaging protrusion 24 and / or recess 26.

[0126] The guide structure does not necessarily have to be spiral, and may be formed in a non-spiral shape. For example, the guide structure 260b shown in Figure 26 extends radially inward from the large diameter surface 22 on which the guide structure 260b is formed to the engaging protrusion 24 and / or recess 26 adjacent thereto in the circumferential direction, while maintaining a horizontal direction, in the orientation shown in Figure 26.

[0127] Figure 31 is a diagram showing an example in which the node 100(4) of the rod-shaped body 1a is guided into the recessed portion 26 by the guide structure 260b of the joint structure 20. Note that Figure 31(c) shows multiple node portions 4 located on the back side of the page by dashed lines. In the orientation shown in FIG. 31, when a rod-shaped body 1a is inserted from one end (upper side) of the joint structure 20 (FIG. 31(a)), the lower part of the node 100(4) arranged at the bottom of the rod-shaped body 1a, which is closer to the insertion direction, abuts against the guide structure 260b (FIG. 31(b)). Next, by rotating the rod-shaped body 1a clockwise relative to the joint structure 20, the node 100(4) is automatically guided from the open end 28 shown in FIG. 26 into the recessed portion 26 (lower recessed portion 26a) (FIG. 31(c)). Note that the other nodes 4 that are not abutting against the guide structure 260b also enter their corresponding recessed portions 26.

[0128] Here, the joint structure 20 can be provided with a guide structure 260c in addition to the guide structure 260b.

[0129] Like the guide structure 260b, the guide structure 260c automatically guides the node portion 4 of the rod-shaped body 1a inserted from one end side (upper side) of the joint structure 20 into the recessed portion 26. The guide structure 260c extends and protrudes radially inward while maintaining a horizontal orientation. The recessed portion 26 guided by the joint structure 260c is a different recessed portion from the recessed portion 26 guided by the guide structure 260b. That is, as explained in Fig. 5(c) above, the recessed portions 26 provided in the joint structure 20 are arranged in two regions that are radially spaced apart and facing each other in a staggered manner so as to correspond to the node portions 4 of the rod-shaped body 1. For this reason, although not shown in Figs. 26 and 31, in a region that faces radially the recessed portion 26 (lower recessed portion 26a) guided by the guide structure 260b, another recessed portion 26 is arranged in a staggered manner below the recessed portion 26. The node portion 100(4) of the rod-shaped body 1a inserted from one end side (upper side) of the joint structure 20 is guided by the guide structure 260c relative to this recessed portion 26 (not shown).

[0130] In addition, in the orientation shown in Figure 31, the joint structure 20 is provided with guide structures 260b' and 260c' that automatically guide the node portion 100 (4) of the rod-shaped body 1b inserted from the other end side (lower side) of the joint structure into the recessed portion 26, similar to the guide structures 260b and 260c.

[0131] As described above, by providing a guide structure (260b, 260b', 260c, 260c') that guides the node portion 4 of the rod-shaped body 1 to the recessed portion 26 of the joint structure 20, even if the rod-shaped body 1 is cut at a position that does not take into account the relationship between pitch and phase in order to adjust the length, it is possible to automatically guide the node portion 4 to match the axial position of the recessed portion 26, and there is no need to adjust the axial position relative to the joint structure.

[0132] [Second Modification of First Embodiment] In this embodiment, the recessed portions 26 of the joint structure 20 have been described as having an asymmetric or symmetrical shape. However, it is of course possible to arrange asymmetric and symmetrical recessed portions in a row in the axial direction, and the arrangement of the recessed portions in this case may be such that asymmetric and symmetrical recessed portions are alternately arranged, or a hybrid structure may be used in which a symmetrical recessed portion is arranged every few recessed portions among a plurality of asymmetrical recessed portions, or an appropriate combination arrangement may be used.

[0133] Of course, the recessed portion 26 is not limited to a non-helical shape such as an asymmetrical or symmetrical shape, and may be a helical shape. Furthermore, the helical shape may extend continuously, or may be a series of approximately helical recessed portions intermittently arranged along a virtual helical path. The node portion 4 may be fitted into the helical recessed portion 26 to relatively displace the node portion 4 along the helical direction. In this case, the helical shape is set as a so-called right-handed helical groove, in which the inner circumferential surface of the recessed portion 26 can slide against the surfaces 14a and 14d of the node portion 4, thereby guiding the direction of displacement of the node portion 4. Needless to say, the inner circumferential surface of the recessed portion 26 may also be set as a so-called left-handed helical groove, in which the inner circumferential surface of the recessed portion 26 slides against the surfaces 14b and 14c, thereby guiding the direction of displacement of the node portion 4. As a result, the joint structure 20 can be displaced in the axial direction by rotation relative to the rod-shaped body 1.

[0134] When the recessed portion 26 has a spiral shape, the shape of the radial end of the engaging protrusion 24 can be set appropriately, and can be set to, for example, a flat shape, a convex curved shape, an acute angle shape, a pointed shape, etc. Furthermore, the spiral recessed portion 26 can have an appropriate spiral groove shape, for example, configured so that the width of the groove narrows gradually or in stages from one end to the middle in the axial direction.

[0135] The joint structure may have both a non-helical recessed portion and a helical recessed portion. Figure 16 shows a joint structure 70 having a non-helical recessed portion and a helical recessed portion, where (a) is a perspective view, (b) is a front view, and (c) is an AA cross-sectional view of (b). The joint structure 70 has a non-helical recessed portion 72a at one end and a helical recessed portion 72b at the other end, with the boundary being the middle portion in the axial direction. Of course, in such a hybrid structure of recesses, the boundary between the non-helical region and the helical region may be directly connected or may have an appropriate gap therebetween.

[0136] When the recessed portion 26 is symmetrical, the recessed portion 26 may have a shape symmetrical about an axis of symmetry parallel to the axial direction, such as a generally elliptical, oval, lip-shaped, rugby-ball-shaped, egg-shaped, or diamond-shaped shape when viewed in the radial direction. That is, the recessed portion 26 has closed ends at both circumferential ends, and has a shape similar or approximate to the shape of the node portion 4 when viewed in the radial direction. Of course, in the joint structure 20, the node portion 4 abuts against the inner circumferential surface excluding the large diameter surface 22 and the recessed portion 26. The recess 26 shown in FIG. 5(d) has closed ends (29, 31) that are closed at both circumferential ends and has a shape similar to the shape of the node 4 when viewed radially. Making the recess symmetrical also allows the joint structure and the rod-shaped body to be connected, making it easy to position and fix the joint structure at the desired axial position of the rod-shaped body, improving the connection between the rod-shaped bodies, and improving the pull-out strength of the joint structure and the rod-shaped body when embedded in hydraulically solidified concrete or other hardening fluids such as mortar or resin before solidification. Furthermore, if the recess is symmetrical, after the node is fitted into the recess, relative rotation of the joint structure with respect to the rod-shaped body is restricted, preventing the node from coming off the recess. As a result, the connection between the joint structure and the rod-shaped body can be strengthened.

[0137] The joint structure 70 shown in Fig. 16 is provided with a confirmation hole 58, which will be described later. This allows the position of the rod-shaped body 1 to be visually confirmed or checked, and simultaneously and easily grasps the position of the rod-shaped body relative to the axial intermediate portion of the joint structure. Note that the confirmation hole 58 does not necessarily have to be provided, and the insertion depth of the rod-shaped body may be restricted by providing the position restricting portion 60 described above. Of course, by providing guide structures 60a, 60b, it is also possible to automatically guide the node portion of the rod-shaped body so that it matches the axial position of the recessed portion.

[0138] In this embodiment, the outer shape of the joint structure has been described as being approximately circular, but this is not particularly limited, and the joint structure may have at least a two-flat shape to facilitate application of torque for relative rotation with respect to the rod-shaped body. Furthermore, the joint structure may have a polygonal outer shape, including a star shape, such as the hexagonal cylindrical joint structure 170 shown in FIG. 17. Of course, the joint structure may be cylindrical with a two-flat shape in a portion of the axial direction, or may have a polygonal shape only in a portion of the axial direction.

[0139] Furthermore, the confirmation hole 58 may have a middle position indicating means for indicating the middle part of the joint structure in the longitudinal direction. Specifically, as shown in Fig. 17, a constricted portion 58a is provided with a narrow opening at a location corresponding to approximately the middle part of the axial direction of the joint structure 170. This makes it possible to visually confirm the position of each rod-shaped body when a rod-shaped body is inserted into each end of the joint structure 170, and simultaneously and easily grasp the position of each rod-shaped body relative to the middle part of the axial direction of the joint structure.

[0140] Returning to Figure 16, the joint structure 70 has engagement holes 74 at both ends. The engagement holes 74 are located at the ends of the insertion hole 21 of the joint structure 70, and have a tapered shape with the inner circumferential surface widening toward the opening. A flat knurling is formed on the inner circumferential surface of the engagement hole 74 along the axial direction. The engagement hole 74 is designed to have a hole shape with a larger diameter than the insertion hole 21 of the joint structure 70 so that a relative rotation prevention member 80 (described later) can be interposed between the engagement hole 74 and the rod-shaped body 1.

[0141] Although the engagement hole 74 here is tapered, it does not necessarily have to be tapered and may be straight, curved, or curved. However, a tapered shape is preferable when attempting to absorb dimensional errors, etc.

[0142] 18 shows a relative rotation prevention member 80 that engages with the joint structure 70, with (a) being a perspective view, (b) being a front view, and (c) being a cross-sectional view. The relative rotation prevention member 80 has a substantially ring-shaped main body 82 and a flange 84. Although the flange 84 is shown here, this is not necessarily required. The relative rotation prevention member 80 also has an inner circumferential surface 86 that surrounds the rod-shaped body 1.

[0143] The main body 82 has an outer shape that can engage with the engagement hole 74. That is, the outer peripheral surface of the main body 82 has a tapered shape that gradually reduces in diameter from the flange 84 side, corresponding to the inner peripheral surface of the engagement hole 74. In addition, a flat knurling is formed on the outer peripheral surface of the main body 82 along the axial direction. Note that the outer peripheral shape of the main body 82 is not limited to a tapered shape, and can be set to a straight shape, a curved shape, a curved shape, a wavy shape, etc., and is preferably a shape that corresponds to the engagement hole 74. Furthermore, the flat knurling along the axial direction is not necessarily limited to a flat knurling shape, and can be set as appropriate as long as it can engage with the anti-rotation means provided in the engagement hole 74 to prevent relative rotation.

[0144] The flange portion 84 has an outer diameter larger than that of the main body portion 82, and a plurality of irregularities 84a are formed along the circumferential direction on its axial end face. These irregularities 84a preferably have a sawtooth or wave shape, and are preferably set so that the extending direction of the irregularities 84a, i.e., the extending direction of the ridge lines 12, is aligned with the radial direction of the relative rotation preventing member 80. As a result, the irregularities 84a on the end face of the flange portion 84 extend radially from the axis.

[0145] The inner circumferential surface 86 is composed of a pair of interference surfaces 86a that can interfere with the node portion 4 without contacting the reduced diameter surface 2 of the rod-shaped body 1, and a pair of non-contact surfaces 86b that face the node portion 4 with a gap between them. That is, the interference surfaces 86a and the non-contact surfaces 86b of the inner circumferential surface 86 are arranged alternately along the circumferential direction. That is, the hole defined in the inner circumferential surface 86 can function as a rod-shaped body insertion hole having a non-circular shape whose shape as viewed in the axial direction roughly corresponds to the outer shape of the rod-shaped body 1 in the axial direction.

[0146] When interposed between the joint structure 70 and the rod-shaped body 1, the relative rotation prevention member 80 can restrict the joint structure 70 from rotating relative to the rod-shaped body 1. Specifically, the relative rotation prevention member 80 is arranged in advance in a state in which it surrounds the outer circumferential surface of the rod-shaped body 1. At this time, the rod-shaped body 1 fits into the rod-shaped body insertion hole in a state in which relative rotation is prevented.

[0147] Next, the rod-shaped bodies 1 are inserted into both ends of the joint structure 70, and the nodes 4 are fitted into the recessed portions 72a, 72b. The relative rotation prevention member 80 is inserted into the engagement hole 74 by sliding it axially toward the joint structure 70. The flat knurling of the main body 82 and the flat knurling of the engagement hole 74 of the joint structure 70 then engage in the circumferential direction. That is, the concave and convex portions of the flat knurlings are matched and engaged in the circumferential direction.

[0148] As a result, the relative rotation prevention member 80 circumferentially engages with both the rod-shaped body 1 and the joint structure 70. That is, the flat knurling on the outer periphery of the main body 82 circumferentially engages with the flat knurling of the engagement hole 74. On the other hand, when the interference surface 86a of the inner circumferential surface 86 is displaced circumferentially from the position facing the reduced diameter surface 2 of the rod-shaped body 1, it interferes with the node portion 4, and as a result, the inner circumferential surface 86 circumferentially engages with the rod-shaped body 1.

[0149] Next, FIG. 19 shows a relative displacement prevention member 90, where (a) is a perspective view, (b) is a front view, and (c) is a cross-sectional view. The relative displacement prevention member 90 is a hollow member having a generally hexagonal outer shape, a hole 90a that can surround the rod-shaped body 1, and a continuous spiral groove 92 on its inner circumferential surface. The relative displacement prevention member 90 also has a flange-shaped end portion, and a plurality of uneven portions 94 are formed along the circumferential direction on one end surface in the axial direction. The uneven portion 94 is configured to be undulating in an appropriate shape that can engage with the uneven portions 84a of the flange portion 84. In this example, the uneven portion 94 is configured to be saw-tooth shaped and extend radially from the axis. However, the present invention is not limited to this, and it goes without saying that a wave shape or other appropriate fitting structure may be used.

[0150] Therefore, at the location where the relative rotation prevention member 80 and the relative displacement prevention member 90 come into contact, the unevenness 84a and the unevenness portion 94 function as a relative rotation prevention mechanism that prevents relative rotation between the two members 80, 90.

[0151] The spiral direction of the spiral groove 92 is set so that the node 4 of the rod-shaped body 1 can be fitted into it. Of course, the spiral direction can be set as appropriate, but here the spiral direction of the spiral groove 92 is set to a left-handed spiral, opposite to the spiral of the recessed portion 72b. By fitting the node 4 into the spiral groove 92, it engages with the node 4 and restricts axial displacement, but when the relative displacement prevention member 90 itself is rotated, it can be displaced in the axial direction relative to the rod-shaped body 1.

[0152] [Joint structure and rod-shaped body connection procedure when using relative rotation prevention members, etc.] The following describes the connection between the joint structure 70 and the rod-shaped body 1 using a rigid connection structure that combines the above-mentioned relative rotation prevention member 80 and relative displacement prevention member 90. Two rod-shaped bodies 1a and 1b are inserted into the joint structure 70, with the node 4 of one rod-shaped body 1a fitting into the recessed portion 72a and the node 4 of the other rod-shaped body 1b fitting into the right-handed spiral recessed portion 72b.

[0153] In this case, the other rod-shaped body 1b is connected first. Specifically, the rod-shaped body 1b is positioned at the opening at the other end (the upper end in FIG. 20) of the joint structure 70, and aligned so that the recessed portion 72b can fit into the node portion 4. Next, as shown in FIG. 20(a), when the joint structure 70 is rotated clockwise relative to the rod-shaped body 1b, the rod-shaped body 1b is displaced relative to the inside of the joint structure 70. That is, due to the rotation of the joint structure 70, the node portion 4 fitted into the recessed portion 72b is guided in the spiral direction, and as a result, the rod-shaped body 1b is displaced relative to the recessed portion 72b in the direction along the spiral, and moves to the innermost portion along the recessed portion 72b.

[0154] Next, one of the rod-shaped bodies 1a is connected. Specifically, as shown in Figure 20(b), the rod-shaped body 1a is inserted into the insertion hole 21 from one end side in the axial direction of the joint structure 70, and the depth position of the rod-shaped body 1a is confirmed using the confirmation hole 58. At this time, the reduced diameter surface 2 of the rod-shaped body 1a is aligned with a position facing the recessed portion 72a of the joint structure 70. In this state, the joint structure 70 can be inserted axially without coming into contact with the rod-shaped body 1a. 20(c), when the joint structure 70 is rotated counterclockwise as indicated by the arrow, the guide space S allows the joint structure 70 to smoothly move relative to the rod-shaped body 1a in the circumferential direction to a position where the outermost diameter portion of the rod-shaped body 1a abuts against the large diameter surface 22. In order to further rotate the joint structure 70 counterclockwise, the joint structure 70 is rotated with a torque large enough to elastically deform the node portion 4 and / or the recessed portion 72a. As a result, the node portion 4 fits into the recessed portion 72a and the tip end of the node portion 4 in the insertion direction moves relative to the rod-shaped body 1a to a position where it abuts against the closed end of the recessed portion 72a, and the joint structure 70 and the rod-shaped body 1a are fixed together.

[0155] Next, the relative rotation prevention member 80 is installed. Specifically, as shown in Figure 21(a), the relative rotation prevention member 80, which has been inserted into the rod-shaped body 1a (1b) in advance, is slid toward the joint structure 70 while surrounding the rod-shaped body 1a (1b) and inserted into the engagement hole 74. Furthermore, the relative displacement prevention member 90, which has been screwed leftward onto the rod-shaped body 1a (1b) beforehand prior to the relative rotation prevention member 80, is rotated in a direction that advances toward the relative rotation prevention member 80, i.e., leftward relative to the rod-shaped body 1a (1b). As a result, the irregularities 84a on the end face of the flange portion 84 and the irregularity portion 94 approach and come into contact with each other, and the irregularities engage with each other.

[0156] By combining the relative rotation prevention member 80 and the relative displacement prevention member 90 in this manner, the rod-shaped body 1 and the joint structure 70 can be connected more firmly. That is, the inner periphery of the relative rotation prevention member 80 engages with the rod-shaped body 1 in the circumferential direction, and the outer periphery engages with the joint structure 70 in the circumferential direction. Therefore, when one of the joint structure 70 and the rod-shaped body 1 rotates relative to the other, the rotation is restricted by the relative rotation prevention member 80. Therefore, the state in which the node portion 4 is fitted into the recessed portions 72a, 72b can be firmly maintained. Furthermore, because the relative displacement prevention member 90 is disposed axially outward of the relative rotation prevention member 80, it is possible to reliably prevent the relative rotation prevention member 80 from coming off the engagement hole 74 in the axial direction.

[0157] Furthermore, although the relative displacement prevention member 90 can easily displace in the circumferential direction relative to the rod-shaped body 1, the circumferential engagement between the flange portion 84 and the uneven portion 94 prevents the relative displacement prevention member 90 from rotating in a direction that could separate it from the joint structure 70, and the relative rotation prevention member 80 and the relative displacement prevention member 90 are firmly fixed together. Therefore, the joint structure 70, the relative rotation prevention member 80, and the relative displacement prevention member 90 can be substantially integrated and connected very firmly to the rod-shaped body 1, making it possible to eliminate the need to inject fluid hardening fillers such as mortar, grout, and adhesives, which have conventionally been necessary.

[0158] The above-mentioned confirmation hole may be closed with a light-transmitting material such as a transparent film or a transparent resin material, as long as it allows at least the rod-shaped body inside the joint structure to be visible. The confirmation hole 58 does not necessarily have to be provided, and the insertion depth of the rod-shaped body may be restricted by providing the aforementioned position restricting portion 60. Of course, by providing guide structures 60a, 60b, it is also possible to automatically guide the node portion of the rod-shaped body so that it aligns with the axial position of the recessed portion.

[0159] Although the main body of the relative rotation prevention member 80 is cylindrical, it may be shaped so as to be elastically deformable in the radial direction. For example, as shown in FIG. 22, the main body 82 may be formed with slits 87 extending along the axial direction. The slits 87 may be formed at predetermined intervals along the circumferential direction, or as shown in FIG. 22(b), the slits 87 may be formed by cutting out a portion of the non-contact surface 86b along the axial direction. Furthermore, the slits 87 may be formed so as to extend widely in the circumferential direction of the main body 82 as shown in FIG. 22(c), and the size and number of the slits may be set as appropriate. By forming such slits 87, the main body 82 can elastically and / or plastically deform so as to bend inward, allowing it to more firmly adhere to the rod-shaped body 1. That is, the outer circumferential surface of the main body 82 is intermittently divided in the circumferential direction by the slits 87, making each portion more susceptible to elastic and / or plastic deformation. Furthermore, when the main body 82 elastically and / or plastically deforms radially inward, the inner circumferential surface of the main body 82 comes into close contact with the outer circumferential surface of the rod-shaped body 1 and presses it radially inward. As a result, the relative rotation preventing member 80 can be more firmly fixed to the rod-shaped body 1. Furthermore, although the outer circumferential surface of the main body 82 has a tapered shape corresponding to the inner circumferential surface of the engagement hole 74, it may also be configured to have a different tapered shape from the engagement hole 74 so that it is pressed radially inward by the inner circumferential surface of the engagement hole 74. Specifically, if the taper angle is slightly gentler than that of the engagement hole 74 and the outer diameter of the axial tip of the main body portion 82 is designed to exceed the inner diameter of the innermost part of the engagement hole 74, the main body portion 82 will gradually be compressed by the inner surface of the engagement hole 74 as it enters the engagement hole 74, and will reliably elastically deform radially inward to adhere firmly to the rod-shaped body 1.

[0160] The joint structure may also be configured to allow insertion of rod-shaped objects having different diameters at one end and both ends in the axial direction. That is, the joint structure may be configured to connect rod-shaped objects having different diameters, and in this case, the cross-sectional area and diameter of a first range from one end to the middle of the axial direction may be configured to be different from the cross-sectional area and diameter of a second range from the other end to the middle of the axial direction.

[0161] Furthermore, the joint structure is not limited to one made up of one member, but may be made up of multiple members.

[0162] [Second embodiment] FIG. 23 shows a joint structure according to a second embodiment, where (a) is a perspective view seen from the front and (b) is a perspective view seen from the side.

[0163] A joint structure 230 according to a second embodiment of the present invention will be described. To fix the rod-shaped body 1 and the joint structure 230, it is necessary to fit the node 4 of the rod-shaped body 1 into the recess 26, and at this time, a torque large enough to elastically deform the node 4 and / or the recess 26 of the rod-shaped body 1 is required. However, depending on the materials of the rod-shaped body 1 and the joint structure 230, a considerable torque may be required to fit the node 4 of the rod-shaped body 1 into the recess 26. Additionally, for example, when forming the guide space portion described in the first embodiment, increasing the amount of guide space S allows the joint structure 230 to smoothly displace in the axial and / or circumferential directions relative to the rod-shaped body 1. Also, when the joint structure 230 and the rod-shaped body 1 are fixed together, the distance between the node portion 4 of the rod-shaped body 1 and the recessed portion 26, etc. of the joint structure 230 tends to increase, and the amount of torque described above may also decrease. On the other hand, there is a risk that the engagement force between the node portion 4 and the recessed portion 26, etc. may be weakened. Conversely, by reducing the amount of guide space S, it becomes easier to strengthen the engagement force between the node portion 4 and the recessed portion 26, etc., but the amount of torque described above increases, and there is a risk that the joint structure 230 will become difficult to displace axially and / or circumferentially relative to the rod-shaped body 1. The joint structure 170 of this embodiment solves this problem by providing an expansion mechanism on the large diameter surface 220, and details thereof will be described below.

[0164] The difference from the first embodiment is that the large diameter surface 220 of the joint structure 230 has an expansion and contraction mechanism, as shown in FIGS. 23(a) and 23(b). In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and detailed description thereof will be omitted.

[0165] A joint structure 230 according to a second embodiment of the present invention will be described. As shown in FIG. 23(a), the joint structure 230 has an inner circumferential surface 23 surrounding the rod-shaped body 1. The inner circumferential surface 23 has an axis C of the joint structure 230. c The large diameter surface 220 is disposed at a position facing each other with a screw (not shown) therebetween, and the engaging protrusion 24 and recess 26 are disposed adjacent to the large diameter surface 220 in the circumferential direction. 23(a) and 23(b), a position restricting portion 60 that restricts the insertion depth of the rod-shaped body 1 is disposed in the axially intermediate portion of the inner peripheral surface 23 of the joint structure 230. The position restricting portion 60 protrudes radially inward from the inner peripheral surface 23 and extends circumferentially. Note that the position restricting portion 60 may be provided with guide structures 60a and 60b.

[0166] The joint structure 230 has an expansion mechanism on the large diameter surface 220. The expansion mechanism extends along the axial direction on the large diameter surface 220, and the large diameter surface 220 is formed into a generally bellows shape when viewed in the axial direction. The vertices of the concaves and convexes that make up this generally bellows shape are formed by an inner vertex IV in the inner diameter direction and an outer vertex OV in the outer diameter direction. The imaginary arc VR indicated by the dashed line in Figure 23 is the orbit that the inner vertex IV traces in the radial direction along the circumferential direction on the large diameter surface 220.

[0167] The imaginary arc VR is set so as to be located radially outward of the outermost diameter portion of the node portion 4 of the rod-shaped body 1 when the rod-shaped body 1 is inserted. That is, the radius of the virtual arc VR is set to be larger than that of the node portion 4 so that the virtual arc VR is in a substantially non-contact state with the node portion 4. The radius of the virtual arc VR is set to be larger than that of the axis C of the joint structure 20. c The distances from the axis C are not limited to being approximately equal, and as long as the joint 4 is not in contact with the axis C, c The distance from the center of gravity may be set to vary along the circumferential direction. As a result, when the rod-shaped body 1 is inserted, a guide space portion set in the radial and circumferential directions is formed between the imaginary arc VR and the outermost diameter portion of the node portion 4 of the rod-shaped body 1. This guide space portion allows relative movement of the rod-shaped body 1 in the radial and circumferential directions.

[0168] When viewed in the axial direction, the insertion hole 21 has a generally elliptical shape with the major axis extending in the direction of the imaginary arc arranged at the opposing position and the minor axis extending in the direction of the engaging protrusion 24 arranged at the opposing position.

[0169] The rod-shaped body 1 has a substantially elliptical shape when viewed in the axial direction, and the position of the inner vertex IV constituting the extension mechanism is set so that the joint structure 230 can be inserted into the rod-shaped body 1 with the major axis direction and minor axis direction of this elliptical shape aligned with the major axis direction and minor axis direction of the insertion hole 21. In other words, if the inner vertex IV protrudes too far radially inward, the elliptical shape (major axis direction) formed by the trajectory of the inner vertices UV becomes smaller, and the joint structure 230 cannot be inserted into the rod-shaped body 1.

[0170] Although the telescopic mechanism in this embodiment has a generally bellows shape, it is not limited to this. The large-diameter surface 220 constituting the telescopic mechanism may have a circumferential length longer than the virtual arc described above. For example, when the joint structure 230 is rotated relative to the rod-shaped body 1, the node 4 and the recessed portion 26 come into contact. In this state, when the joint structure 230 is further rotated with a predetermined torque, the distance between the opposing recessed portions 26 is slightly extended by the telescopic mechanism. Therefore, compared to a case without this telescopic mechanism, it is possible to more easily fit the node 4 of the rod-shaped body 1 into the recessed portion 26. In other words, the expansion mechanism functions as an expansion section for expanding the internal space defined by the inner circumferential surface 23 of the joint structure 230 . The structure for expanding the internal space can be appropriately set, and multiple radially separable sections may function as expansion sections, but a separate member or mechanism is required to support the sections together in a generally integrated manner and to displace them radially and / or circumferentially.

[0171] In summary, the joint structure 230 of this embodiment facilitates the engagement of the node portion 4 with the recessed portion 26 by providing an expansion mechanism that can expand somewhat in the opposing direction of the recessed portions 26 that are disposed facing each other and spaced apart in the radial direction on the inner circumferential surface 23. More specifically, the expansion mechanism only needs to set the circumferential length of the large diameter surface 220 to be longer than the imaginary arc drawn by the inner vertices of the large diameter surface 220 within the circumferential range in which the large diameter surface 220 is formed.

[0172] When a bellows shape is used as the expansion mechanism, the number of vertices (inner vertex IV and outer vertices OV) of the concave and convex portions constituting the bellows shape is not particularly limited. For example, the joint structure 241 shown in Fig. 24(a) has a substantially bellows shape as the expansion mechanism, which is composed of one inner vertex IV and two outer vertices OV on the inner diameter surface 221.

[0173] 24(b) has an expansion mechanism in which the thickness of the large diameter surface 222 is thinned. In this case, if the thinned portion of the large diameter surface (thin portion) is flexed and elastically deformed, it functions as an expansion portion for expanding the internal space defined by the inner circumferential surface 23 of the joint structure 242. That is, in the initial state in which the thin portion is not elastically deformed, the joint structure is in a state in which the rod-shaped body 1 is inserted, and when the joint structure rotates relative to the rod-shaped body 1 and the node portion 4 is displaced in the circumferential direction from the position facing the large diameter surface 222, the inner circumferential surface 23 interferes with the node portion 4, thereby restricting the relative rotation. At this time, the thin portion of the recessed portion 26 disposed opposite the joint structure 242 is flexed and elastically deformed so that the distance in the facing direction is expanded, making it easier for the node portion 4 of the rod-shaped body 1 to fit into the recessed portion 26.

[0174] The thin-walled portion does not need to be provided over the entire large diameter surface, but may be provided only on a part of it.

[0175] [Modification of the second embodiment] In the second embodiment, an expansion mechanism having a substantially bellows shape or the like is provided in the joint structure 230, and is described as functioning as an expansion section for expanding the internal space defined by the inner circumferential surface 23 of the joint structure 230. As a modified example of this expansion mechanism, a case where a slit 25 is provided in the joint structure 250 will be described. As shown in FIG. 27 , the slit 25 is formed in the large diameter surface 22 of the joint structure 250 so as to extend in the axial direction. The shape of the joint structure 250 is substantially C-shaped when viewed in the axial direction. When the joint structure 250 is rotated relative to the rod-shaped body 1, the nodes 4 and the recessed portions 26 come into contact with each other. In this state, when the joint structure 250 is further rotated relative to the rod-shaped body 1 with a predetermined torque, the distance between the opposing recessed portions 26 increases slightly due to the presence of the slits 25. In other words, the spacing between the slits 25 increases, and the distance between the opposing recessed portions 26 also increases. Therefore, compared to when the slits 25 are not provided, it becomes easier to fit the nodes 4 of the rod-shaped body 1 into the recessed portions 26. The slits 25 thus provided in the joint structure 250 function as expansion portions for expanding the internal space defined by the inner peripheral surface 23 of the joint structure 250 . The slits 25 do not necessarily have to be provided on the large diameter surface 23, but may extend in the axial direction on the engaging projections 24 and recesses 26 that are adjacent in the circumferential direction of the large diameter surface 22. In addition to providing the slit 25 in the joint structure 250, a thin-walled portion may also be provided. For example, the thin-walled portion is located opposite the slit 25 across the axis, and is formed by thinning the thickness of a portion of the large diameter surface 22, so as to be elastically deformable so as to expand the internal space.

[0176] [Procedure for connecting the rod-shaped body to the joint structure with the expansion mechanism] An example of a procedure for connecting a pair of rod-shaped bodies 1 using a joint structure 250 having a slit 25 will be described below. Here, the explanation will be given assuming that one end of one rod-shaped body 1b (see FIG. 28) is partially buried and fixed in the ground or the like, and that the other rod-shaped body 1a (see FIG. 28) is connected to the other rod-shaped body 1b with the joint structure 250 sandwiched therebetween.

[0177] First, as shown in Figure 28(a), the other end of the rod-shaped body 1b fixed to the ground or the like is inserted into the insertion hole 21 of the joint structure 250, and the joint structure 250 is displaced toward the rod-shaped body 1b. The joint structure 250, which is oriented so as not to interfere with the node portion 4 of the rod-shaped body 1b, is displaced in the axial direction, and the rod-shaped body 1b is inserted to a position where it abuts against the guide structure 260c (see Figure 26). Next, as shown in Figure 28(b), the joint structure 250 is rotated clockwise relative to the rod-shaped body 1b, and the joint structure 250 and the rod-shaped body 1b are fixed together.

[0178] When the joint structure 250 is rotated relative to the rod-shaped body 1b, the recessed portion 26 of the joint structure 250 and the node portion 4 of the rod-shaped body 1b interfere with each other, but the joint structure 250 is elastically deformed, widening the spacing of the slit 25. When the node portion 4 is fitted into the recessed portion 26, the slit 25 narrows to the original spacing before widening or to a spacing close to that spacing, and as a result, the inner peripheral surface 23 of the joint structure 250 radially compresses the outer peripheral surface of the rod-shaped body 1a.

[0179] Next, the other rod-shaped body 1a is inserted into and fixed to the joint structure 250. Specifically, in the orientation shown in FIG. 28(c), the rod-shaped body 1a is inserted into the insertion hole 21 of the joint structure 250, which opens upward. The rod-shaped body 1a is inserted to a position where it abuts against the guide structure 260b (see FIG. 26). Next, as shown in FIG. 28(d), the rod-shaped body 1a is rotated clockwise relative to the joint structure 250, and the joint structure 250 and the rod-shaped body 1a are fixed together.

[0180] When the rod-shaped body 1a is rotated relative to the rod-shaped body 1a, the recessed portion 26 of the joint structure 250 interferes with the node portion 4 of the rod-shaped body 1a, but the joint structure 250 elastically deforms, widening the spacing of the slit 25. When the node portion 4 fits into the recessed portion 26, the slit 25 narrows to the original spacing before widening or to a spacing close to that spacing, and as a result, the joint structure 250 compresses the rod-shaped body 1a in the radial direction. By the above procedure, the rod-shaped bodies 1a and 1b can be connected by the joint structure 250 while compressing the rod-shaped bodies 1a and 1b radially inward.

[0181] When a joint structure having an expansion and contraction mechanism is used, a restricting means may be used to restrict the expansion of the internal space of the joint structure after the rod-shaped bodies are connected to each other. The restricting means may be a cylindrical member that surrounds at least the outer circumferential surface of the joint structure and has an inner circumferential surface that circumferentially contacts the outer circumferential surface. For example, the restricting means may have an inner diameter that is approximately the same as the outer diameter of the joint structure 250 through which the rod-shaped body 1 is inserted. Of course, the inner diameter of the restricting means may be set to be equal to or smaller than the outer diameter of the joint structure through which the rod-shaped body is inserted.

[0182] The restricting means surrounds the joint structure 250 and restricts the expansion of the joint structure 250 when an attempt is made to pull out the rod-shaped body 1 from the joint structure 250 with the node portion 4 of the rod-shaped body 1 fitted in the recess 26 of the joint structure 250. That is, when the slits 25 are used as the expansion / contraction mechanism, the restricting means restricts the spacing of the slits 25 from widening. Note that the restricting means may be further pressed against the joint structure 250 to forcibly reduce the spacing of the slits 25 from the original distance, thereby compressing the rod-shaped body 1 within the joint structure.

[0183] FIG. 29 shows the restricting means 300, with (a) being a perspective view and (b) being a longitudinal cross-sectional view. The restricting means 300 is generally cylindrical and has an inner peripheral surface that creates an internal space 302 that surrounds the rod-shaped body 1 and the joint structure 250. The outer peripheral shape of the restricting means 300 is generally hexagonal when viewed in the axial direction of the insertion hole, but is not limited to this. For example, by making it a shape with two flats or a polygonal shape including a convex or concave shape, it becomes easier to transmit torque to the entire member via the tool. Note that the outer peripheral shape of the restricting means 300 is not limited to a polygonal shape and may be other shapes such as a circle or an ellipse. The internal space 302 has a first space 304 surrounding the rod-shaped body 1 and a second space 306 surrounding the joint structure 250. In the internal space 302, the first space 304 and the second space 306 are formed in this order from the top of the joint structure 250 in the orientation shown in FIG. 29(b). The second space 306 has a larger diameter than the first space 306 and is connected to it. The inner circumferential surface that constitutes the internal space 302 has a female screw helical structure 310 that screws into the rod-shaped body 1 in the first space 304, and has an abutment surface 312 that circumferentially abuts against the outer circumferential surface of the joint structure 250 in the second space 306. The second space 306 is set to have an inner diameter dimension that is approximately the same as or slightly larger than the outer diameter of the outer peripheral surface of the approximately cylindrical joint structure 250. Note that the second space 306 does not need to have an approximately cylindrical shape, but has an inner peripheral shape that corresponds to the outer peripheral shape of the joint structure 250. For example, in the case of a polygonal prism-shaped joint structure as shown in Fig. 17, the inner peripheral shape of the second space 306 is also set to have an inner dimension that is approximately the same as or slightly larger than the outer diameter of the polygonal prism-shaped joint structure.

[0184] The female screw helical structure 310 forms a right-handed helical groove, and the node portion 4 of the rod-shaped body 1 fits into the helical groove to guide the direction of displacement of the node portion 4 along the direction in which the helical groove extends. It goes without saying that the female screw helical structure 310 is not limited to one having a right-handed helical groove, and may also have a left-handed helical groove.

[0185] The restricting means 300 does not necessarily have to have the first space 304 surrounding the rod-shaped body 1 and / or the female screw helical structure 310, but only needs to have at least the second space 306 surrounding the joint structure 250.

[0186] The restricting means 300 may also have a torque transmitting portion at one end that is non-circular and transmits torque applied from a tool to the entire member.

[0187] The abutment surface 312 abuts against the outer peripheral surface of the joint structure 250 so as to surround it, thereby preventing the joint structure 250 from expanding due to the expansion mechanism. That is, when the spiral groove formed in the first space 304 is threadedly engaged with the node portion 4 of the rod-shaped body 1, the inner surface (abutment surface 312) of the second space 306 abuts against the outer surface of the joint structure 250, and the inner surface 23 of the joint structure 250 presses against the outer surface of the rod-shaped body 1.

[0188] The abutment surface 312 may be formed in a generally tapered shape so as to gradually widen the second space 306 toward the opening into which the joint structure 250 is inserted. The generally tapered abutment surface 312 allows the second space 306 to have an opening that is wider than the outer diameter of the joint structure 250 and a shape in which the inner diameter gradually narrows along the insertion direction of the joint structure 250.

[0189] In this case, the minimum inner diameter of the abutting surface 312 may be set to be less than the outer diameter of the joint structure 250. In this case, the joint structure 250 can be easily inserted into the second space 306, and further, the pressure contact state of the abutting surface 312 against the outer circumferential surface of the joint structure 250 is improved, so that the joint structure 250 and the rod-shaped body 1 can be more firmly fixed. Furthermore, when the abutment surface 312 is tapered, the outer peripheral surface of the joint structure 250 can be set to a tapered shape that is approximately parallel to the abutment surface 312, thereby increasing the contact area between the abutment surface 312 and the joint structure 250, and further improving the pressure exerted by the regulating means 300 on the outer peripheral surface of the joint structure 250, thereby enabling the joint structure 250 and the rod-shaped body 1 to be fixed more firmly.

[0190] [Joint structure with expansion and contraction mechanism and procedure for connecting rod-shaped body and restricting means] An example of a procedure for connecting rod-shaped bodies 1a and 1b using a joint structure 250 when using a restricting means 300 will be described. As in the above, one end of one rod-shaped body 1b (see FIG. 30) is assumed to be partially buried and fixed in the ground or the like, and the other rod-shaped body 1a (see FIG. 30) is connected to it via a joint structure 250. Also, restricting means 300 is assumed to be screwed onto the rod-shaped bodies 1a and 1b in advance. The restriction means 300 is oriented relative to the rod-shaped bodies 1a and 1b so that the opening of the second space 306 faces the joint structure 250. That is, in Fig. 30, the restriction means 300 threaded onto the rod-shaped body 1b is disposed so that the opening of the second space 306 faces upward in the orientation shown in Fig. 30, and the restriction means 300 threaded onto the rod-shaped body 1a is disposed so that the opening of the second space 306 faces downward in the orientation shown in Fig. 30.

[0191] First, as shown in FIG. 30(a), the other end of the rod-shaped body 1b, which is fixed to the ground or the like, is inserted into the insertion hole 21 of the joint structure 250, and the joint structure 250 is displaced toward the rod-shaped body 1b. When inserting the joint structure 250 toward the rod-shaped body 1b, as shown in FIG. 27, the engaging convex portion 24 and the concave portion 26 of the joint structure 250 are aligned with positions facing the reduced diameter surface 2 of the rod-shaped body 1b, and the large diameter surface 22 of the joint structure 250 is aligned with a position facing the node portion 4 of the rod-shaped body 1b. In this state, the joint structure 250 can be inserted along the axial direction without interfering with the rod-shaped body 1b. That is, the joint structure 250 is displaced axially in a direction that does not interfere with the node portion 4 of the rod-shaped body 1b. Then, after inserting the rod-shaped body 1b to a position where it abuts against the guide structure 260c (see FIG. 26), the joint structure 250 is rotated clockwise relative to the rod-shaped body 1b to fix the joint structure 250 and the rod-shaped body 1b.

[0192] Next, the other rod-shaped body 1a is inserted into and fixed to the joint structure 250. Specifically, in the orientation shown in Figure 30(b), the rod-shaped body 1a is inserted into the insertion hole 21 of the joint structure 250, which opens upward. After the rod-shaped body 1a is inserted to a position where it abuts against the guide structure 260b (see Figure 26), the rod-shaped body 1a is rotated clockwise relative to the joint structure 250 as shown in Figure 30(c), thereby fixing the joint structure 250 and the rod-shaped body 1a.

[0193] Next, each of the restricting means 300 threadedly engaged with the rod-shaped bodies 1a and 1b is rotated so that the restricting means 300 surrounds the joint structure 250. That is, when viewed from the direction from the rod-shaped body 1a side toward the rod-shaped body 1b side shown in Figure 30(d), the restricting means 300 threadedly engaged with the rod-shaped body 1b is rotated counterclockwise and is relatively displaced toward the joint structure 250 side, and the restricting means 300 threadedly engaged with the rod-shaped body 1a is rotated clockwise and is relatively displaced toward the joint structure 250 side.

[0194] Each of the restricting means 300 causes the joint structure 250 to enter the second space 306 by the above-mentioned relative displacement, and the abutting surface 312 presses the outer circumferential surface of the joint structure 250 radially inward. In this way, by using the restricting means 300, it is possible to reliably prevent the slit 25 (expansion mechanism) of the joint structure 250 from opening. In addition, the restricting means 300 compresses the joint structure 250 radially inward with the abutment surface 312, thereby increasing the compressive force of the joint structure 250 on the rod-shaped bodies 1a, 1b, and more firmly fixing the rod-shaped bodies 1a, 1b and the joint structure 250 together.

[0195] As described above, the components of the first and second embodiments described above can be combined with each other as long as there is no contradiction.

[0196] For example, the position restricting portion 60 described in the first embodiment is not necessarily required. It is also possible to simply form a guide space in the joint structure. In this case, the joint structure may have an insertion hole through which a rod-shaped body can be inserted axially, and the rod-shaped body is connected by engaging its inner periphery with nodes arranged in the axial direction and protruding radially outward on the rod-shaped body. The inner periphery may have engaging protrusions arranged in the axial direction and capable of engaging with the nodes, at least one or more recesses arranged alternately with the engaging protrusions in the axial direction and recessed so that the nodes can be fitted therein, and large-diameter surfaces circumferentially adjacent to the engaging protrusions and the recesses. When the rod-shaped body is inserted, a guide space is formed between the large-diameter surface and the outermost diameter portion of the rod-shaped body, extending radially and circumferentially. The guide space allows relative movement of the rod-shaped body in the radial and circumferential directions. Forming the guide space in this manner allows the rod-shaped body to be smoothly inserted into the joint structure and rotate relative to the rod-shaped body in the circumferential direction.

[0197] As another example, an expandable portion may be formed in the joint structure without providing a position restricting portion. In this case, the joint structure may have an insertion hole through which a rod-shaped object can be inserted axially, and the rod-shaped object is connected by engaging its inner periphery with nodes arranged in the axial direction of the rod-shaped object and protruding radially outward. The inner periphery may have engaging protrusions arranged in the axial direction and capable of engaging with the nodes, at least one or more recessed portions alternately arranged with the engaging protrusions in the axial direction and recessed so that the nodes can be fitted therein, and large-diameter surfaces circumferentially adjacent to the engaging protrusions and the recessed portions. The expansion mechanism may be configured to be slightly expandable and contractible in the direction in which the opposing recessed portions face each other. This allows for some expansion in the direction in which the opposing recessed portions face each other, making it easier to fit the nodes and the recessed portions together.

[0198] In addition, the materials for the joint structure, rod-shaped body, rotation prevention member, relative rotation prevention member, and relative displacement prevention member in each embodiment can be metal materials such as iron-based materials and non-ferrous materials, resin materials, reinforced resin materials, or combinations of these. [Explanation of symbols]

[0199] 1, 1a, 1b... Rod-shaped body, 2... Reduced diameter surface, 4... Node portion, 4a... End surface, 6... Concave diameter surface, 10, 152... Tip portion, 12... Ridge line, 13a... Curve, 13b... Straight line, 14a to 14d... Surface, 20, 70, 170, 230, 241, 242, 243, 250... Joint structure, 21... Insertion hole, 22, 220, 2 21, 222, 223... Large diameter surface, 23... Inner peripheral surface, 24... Engagement protrusion, 25... Slit, 26, 30, 72... Recessed portion, 26a... Lower recessed portion, 26b... Upper recessed portion, 28, 32... Open end, 29, 31... Closed end, 40... Rotation prevention member, 42... Spacer portion, 44... Hole, 58... Confirmation hole, 58a... Narrowed portion, 60... Position restricting portion, 60a, 60b, 260b, 260c... Guide structure, 72a... Non-helical concave portion, 72b... Helical concave portion, 74... Engagement hole, 80... Relative rotation prevention member, 82... Main body portion, 84... Flange portion, 84a... Concave and concave portions, 86... Inner peripheral surface, 86a... Interference surface, 86b... Non-contact Contact surface, 87...slit portion, 90...relative displacement prevention member, 90a...hole, 92...spiral groove portion, 94...concave and concave portion, 150...joint locking portion, 151...boundary portion, 152...tip portion, 300...regulating means, 302...internal space, 304...first space, 306...second space, 310...spiral structure, 312...contact surface

Claims

1. A cylindrical body structure having an insertion hole through which a rod-shaped body can be inserted in an axial direction, and an inner periphery of the cylindrical body is engaged with nodes arranged in a row in the axial direction of the rod-shaped body and protruding radially outward to connect the rod-shaped body, At least one recessed portion is provided on the inner periphery so that the node portion can be fitted thereinto; a large diameter surface circumferentially adjacent to the recessed portion, A cylindrical body structure characterized in that, when the rod-shaped body is inserted, a guide space portion is formed between the large diameter surface and the outermost diameter portion of the rod-shaped body in the radial and circumferential directions, and the guide space portion allows relative movement of the rod-shaped body in the radial and circumferential directions.

2. The guide space portion has a radius of r ｄ１ and the radius of the outermost part of the node of the rod-shaped body is r ｌｍａｘ In this case, r ｄ１ >r ｌｍａｘ 2. The cylindrical structure according to claim 1, wherein the following relationship is satisfied:

3. a reduced diameter surface is connected to a circumferential end of the node portion of the rod-shaped body, The radius of the node of the rod-shaped body is r ｌ and the radius of the reduced diameter surface is r ｓ In this case, in the node portion, r ｌｍａｘ ≧r ｌ and on the reduced diameter surface, r ｌｍａｘ ≧r ｓ 3. The cylindrical structure according to claim 2, wherein the following relationship is satisfied:

4. 2. The cylindrical body structure according to claim 1, wherein the guide space allows the rod-shaped body to rotate in one direction by a predetermined angle as the relative movement of the rod-shaped body in the circumferential direction.

5. 5. The cylindrical body structure according to claim 4, wherein the guide space allows the rod-shaped body to rotate in the other direction by a predetermined angle as a relative movement of the rod-shaped body in the circumferential direction.

6. 6. The cylindrical body structure according to claim 5, wherein the predetermined angle allowing rotation in one direction is greater than the predetermined angle allowing rotation in the other direction.

7. The cylindrical body structure according to claim 1, characterized in that, when viewed in a plan view from the axial direction, a virtual line passing through approximately the center of the large diameter surface and the axis is used as a reference line, and the circumferential shape of the large diameter surface is formed with different shapes on the side of the engagement rotation direction with the rod-shaped body and the side of the counter-engagement direction with the reference line as a boundary.

8. The circumferential shape of the large diameter surface is such that the radius of the large diameter surface is r ｄ１ An arc shape is formed, The radius is r ｄ１ >r ｌｍａｘ 8. The cylindrical structure according to claim 7, wherein the following relationship is satisfied:

9. The circumferential shape of the large diameter surface is such that the radius of the large diameter surface at the location of the boundary is r ｄ０ On the counter-engagement rotation side, the radius of at least the large diameter surface is set to r ｄ２ An arc shape is formed, The radius is r ｄ２ ≦r ｌｍａｘ <r ｄ0 8. The cylindrical structure according to claim 7, wherein the following relationship is satisfied:

10. The circumferential shape of the large diameter surface is such that, on the counter-engagement direction side, the radius of the large diameter surface is increased by at least r ｄ２ , r ｄ3 An arc shape is formed, The radius is r ｄ3 ≦r ｌｍａｘ <r ｄ２ 8. The cylindrical structure according to claim 7, wherein the following relationship is satisfied:

11. The cylindrical body structure described in claim 7, characterized in that the circumferential shape is formed into an arc shape that is approximately a perfect circle with a substantially constant first radius of curvature in the range along the rotational direction on the engagement rotational direction side.

12. The cylindrical body structure according to claim 7, characterized in that when the rod-shaped body is rotated relative to the engaging rotation direction, the outer diameter portion of the node portion of the rod-shaped body abuts against either of the large diameter surfaces, thereby creating an interference state with the rod-shaped body.

13. The cylindrical body structure described in claim 11, characterized in that the circumferential shape is formed as an arc shape having a second radius of curvature smaller than the first radius of curvature in at least a portion of the range along the rotational direction on the anti-engagement rotational direction side.

14. The cylindrical body structure according to claim 13, characterized in that the radial length of the second radius of curvature is set to be shorter than the radial length from the axis of the rod-shaped body to the outer diameter portion at the node.

15. 8. The cylindrical body structure according to claim 7, wherein the circumferential shape of the large diameter surface on the engagement rotation direction side is substantially the same as or similar to the circumferential shape of the large diameter surface located point-symmetrically with respect to the axis.

16. 8. The cylindrical body structure according to claim 7, wherein the circumferential shape of the large diameter surface on the counter-engagement rotational direction side is substantially the same as or similar to the circumferential shape of the large diameter surface located point-symmetrically with respect to the axis.

17. The rod-shaped body is inserted, and the rod-shaped body is When the large diameter surface and the outer diameter portion of the node portion of the rod-shaped body are in contact with each other by the relative rotation in the engagement direction, the sum of the length of the large diameter surface in the thickness direction at the contact point and the length from the axis of the rod-shaped body to the contacting outer diameter portion, The cylindrical body structure according to claim 7, characterized in that when the large diameter surface and the outer diameter portion of the node portion of the rod-shaped body are in contact with each other by rotating relative to each other in the anti-engagement direction, the sum of the thickness direction length of the large diameter surface at the contacting point and the length from the axis of the rod-shaped body to the contacting outer diameter portion satisfies approximately the same relationship.

18. the recessed portions are arranged in two regions on the inner circumference that are spaced apart from each other in the radial direction and that face each other, an expansion / contraction mechanism that can expand to some extent in the opposing direction of the recessed portion; When viewed in a plan view from the axial direction, the extension / contraction mechanism is formed to have a circumferential length longer than an imaginary arc drawn in a radial direction along the circumferential direction of the large diameter surface, The cylindrical body structure according to claim 1, characterized in that, when the rod-shaped body is inserted, a guide space portion is formed between the virtual arc and the outermost diameter portion of the rod-shaped body in the radial and circumferential directions, and the guide space portion allows relative movement of the rod-shaped body in the radial and circumferential directions.

19. When viewed in a plan view from the axial direction, the expansion and contraction mechanism is formed in a substantially bellows shape in a radial direction along a circumferential direction of the large diameter surface, the bellows shape being configured with an inner vertex in an inner diameter direction and an outer vertex in an outer diameter direction, 19. The cylindrical body structure according to claim 18, wherein the imaginary arc is a path that the inner vertex traces in a radial direction along a circumferential direction.

20. When viewed from the axial direction, the cylindrical structure is substantially C-shaped and has a slit extending in the axial direction. the recessed portions are arranged in two regions on the inner circumference that are spaced apart from each other in the radial direction and that face each other, an expansion / contraction mechanism that can expand to some extent in the opposing direction of the recessed portion; 2. The cylindrical body structure according to claim 1, wherein the expansion mechanism expands the distance between the opposing recessed portions by expanding the spacing between the slits.

21. 21. The cylindrical body structure according to claim 20, further comprising a restricting means for restricting the spacing of the slit from widening when the node of the rod-shaped body is fitted in the recess.

22. the restricting means has a first space surrounding the rod-shaped body and a second space surrounding the cylindrical body structure, the first space has an inner circumferential surface formed with a spiral groove that can be threadably engaged with the node portion of the rod-shaped body, The cylindrical structure according to claim 21, wherein the second space has an inner peripheral surface that surrounds the outer peripheral surface of the cylindrical structure and abuts against the outer peripheral surface in a circumferential manner.

23. The regulating means is characterized in that, when the spiral groove formed in the first space is threadedly engaged with the node portion of the rod-shaped body, the inner surface of the second space abuts against the outer surface of the tubular body structure, and the inner surface of the tubular body structure presses against the outer surface of the rod-shaped body.

24. the inner periphery is provided with a row of engaging projections in the axial direction, the engaging projections being engageable with the nodes; At least one or more recessed portions alternate with the engaging protrusions in the axial direction and are recessed so that the nodes can be fitted therein; a large diameter surface circumferentially adjacent to the engaging protrusion and the recess, 2. The cylindrical body structure according to claim 1, wherein a position restricting portion for restricting the insertion depth of the rod-shaped body is provided at an axially intermediate portion of the large diameter surface.

25. 25. The cylindrical body structure according to claim 24, wherein the position regulating portion has a guide structure that guides the node portion of the rod-shaped body into the recessed portion.

26. 25. The cylindrical body structure according to claim 24, wherein the position restriction portion is formed in the form of an intermittent or continuous spiral strip.

27. The cylindrical body structure according to claim 26, characterized in that the position regulating portion is formed to protrude radially inward from the large diameter surface, and the height of the protrusion is formed to be approximately the same as the height of the node portion.

28. When the rod-shaped body is inserted, a guide space in the radial direction and the circumferential direction is formed between the large diameter surface and the outermost diameter portion of the rod-shaped body, 25. The cylindrical body structure according to claim 24, wherein the guide space allows relative movement of the rod-shaped body in the radial and circumferential directions.

29. 29. The cylindrical body structure according to claim 28, wherein the guide space allows the rod-shaped body to rotate in one direction by a predetermined angle as the relative movement of the rod-shaped body in the circumferential direction.

30. 30. The cylindrical body structure according to claim 29, wherein the guide space allows the rod-shaped body to rotate in the other direction by a predetermined angle as the relative movement of the rod-shaped body in the circumferential direction.

31. 31. The cylindrical body structure according to claim 30, wherein the predetermined angle allowing rotation in one direction is greater than the predetermined angle allowing rotation in the other direction.

32. the recessed portion has a non-helical shape; 25. The cylindrical body structure according to claim 24, wherein the non-helical shape is either a symmetrical shape or an asymmetrical shape with respect to the axial direction as an axis of symmetry when viewed in the radial direction.

33. The symmetrical shape has closed ends at both ends in the circumferential direction, The main body of the cylindrical structure has an expansion portion that allows the internal space to be expanded, The cylindrical body structure according to claim 32, characterized in that the expansion portion is capable of transitioning between a state in which the node portion is received in the inner circumference and a state in which the insertion hole is expanded to receive the node portion in the inner circumference.

34. 33. The cylindrical body structure according to claim 32, wherein the expansion portion has an elastic deformation mechanism.

35. 33. The cylindrical body structure according to claim 32, wherein one circumferential end of the asymmetrically shaped recessed portion is an open end, and the node portion can be received from the open end side.

36. The cylindrical structure according to claim 35, characterized in that the other circumferential end of the asymmetrically shaped recessed portion is a closed end, and the closed end can restrict circumferential displacement of the node portion.

37. 25. The cylindrical body structure according to claim 24, further comprising an expansion mechanism that allows slight expansion and contraction in the opposing direction of the recessed portions disposed opposite to each other.

38. 38. The cylindrical body structure according to claim 37, wherein the expansion mechanism is formed with a circumferential length longer than an imaginary arc drawn in the radial direction along the circumferential direction of the large diameter surface.

39. The cylindrical body structure according to claim 38, characterized in that the expansion and contraction mechanism is formed in a radial bellows shape along the circumferential direction of the large diameter surface.

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