JP7787139B2 - Coupler for deformed rebar using threaded rebar - Google Patents

Description

The present invention relates to a coupler for deformed reinforcing bars that uses threaded reinforcing bars. More specifically, it relates to a fastening coupler in which the end of one opposing reinforcing bar is friction-welded and the other reinforcing bar is inserted into the coupler, preventing loosening between the reinforcing bar and the coupler and forming an extended reinforcing bar that transmits axial force.

When constructing buildings and civil engineering structures using reinforced concrete, the deformed rebars (threaded rebars, bamboo rebars, etc.) used as concrete reinforcement are manufactured to standard lengths, such as 12 meters, to facilitate easy transportation from the factory to the construction site.

However, when used, they are often extended at the construction site to suit the size of the building and the length of the application area. Both threaded and bamboo-knotted rebars are gradually deformed and shaped by the caliber formed on the roll surface during the rolling process, but the rolls gradually become rough and wear out. Although the roughness can be removed by surface grinding and continued use is possible, a reduction in the diameter of the rolling roll is unavoidable, and the knot pitch will vary slightly depending on the time of manufacture. The tooth profile formed in the coupler's connecting hole is made to match the thread pitch of the standard dimensions of the rebar, but with a slightly wider pitch to take into account the rebar's forming tolerances. Therefore, although it is possible to absorb the difference in thread pitch between the coupler and rebar and allow them to interlock, it is unavoidable that some gaps will remain when they interlock.

The gaps between the tooth surfaces can be filled with grout (e.g., mortar) to prevent rattle, or a machine screw can be threaded from the outside of the coupler toward the surface of the rebar to prevent it from coming loose. Examples of the former are proposed in Patent Document 1 (U.S. Patent No. 4,666,326) and Patent Document 2 (JP 2018-178365), while examples of the latter are proposed in Patent Document 3 (U.S. Patent No. 5,046,878) and Patent Document 4 (U.S. Patent No. 7,107,735). In both cases, the goal of achieving a perfect fastening results in the length of the coupler and the increased fastening load. Therefore, the emergence of a coupler that allows for easy torque management (achieved at low torque and with uniform fastening force) to prevent rattle and prevent it from coming loose is eagerly awaited.

Furthermore, it is possible to gradually reduce or increase the diameter of rebar depending on the application area of the building, or to change deformed rebar from threaded joints to bamboo joints. It may also be necessary to apply it to joints. This is because it can reduce the amount of rebar used and encourage the use of stock.

U.S. Patent No. 4,666,326 Patent Publication No. 2018-178365 U.S. Patent No. 5,046,878 U.S. Patent No. 7,107,735

The present invention has been developed in consideration of the above circumstances, and its object is to provide a coupler that can firmly fasten a first reinforcing bar and a second reinforcing bar in the axial direction by utilizing the creak of the screw threads.

The coupler for deformed reinforcing bars using threaded reinforcing bars of the present invention is used to join the ends of opposing reinforcing bars to form an extended reinforcing bar that transmits axial force, as shown in Figure 1(a). Its features are as follows: The coupler 10 comprises a main cylinder 11 to which the end of one reinforcing bar 4L is friction-welded, and a secondary cylinder 12 that is threadedly fitted into the main cylinder on the side opposite the friction-welded side of a blind hole 5H drilled along the axis of the main cylinder.
On the friction welding side of the pocket hole 5H, a pocket hole female thread 5F is formed into which the tip portion of the screw joint 4T of the other reinforcing bar 4R is screwed, and on the anti-friction welding side of this pocket hole, an enlarged diameter female thread 9F is provided which is concentric with the pocket hole female thread 5F but has a larger diameter than the pocket hole female thread 5F.
The secondary cylinder 12 is provided with a sleeve portion 8 having a sleeve portion male thread 8M that screws onto the expanded female thread 9F, and a nut portion 13 that is coaxial with the sleeve portion and integrally formed at the end of the sleeve portion, the expanded female thread 9F having a pitch that differs from the pitch of the thread joint 4T of the other rebar 4R, and the nut portion 13 has a nut portion female thread 13F that screws onto the thread joint 4T of the other rebar 4R and has the same pitch and phase as the pocket hole female thread 5F. The sleeve hole 8H of the sleeve portion 8 is formed with a sleeve portion female thread 8F that has the same pitch and phase as the nut portion female thread 13F.

In another invention, as shown in FIG. 18(b), a coupler 10X comprises a main cylinder 11X to which the end of one reinforcing bar 4L is frictionally welded, and a secondary cylinder 12X that is screwed onto the outside of the main cylinder on the side opposite to the frictional welded side. On the frictional welded side of a pocket hole 5H drilled along the axis of the main cylinder 11X, there is a pocket hole female thread 5F into which the tip portion of the screw joint 4T of the other reinforcing bar 4R is screwed. On the side opposite to the frictional welded side of the outer circumferential surface of the main cylinder 11X, there is an expanding male thread 9M that is concentric with the pocket hole female thread 5F but has a larger diameter than the pocket hole female thread.
The secondary cylinder 12X is provided with a sleeve portion 8X having a sleeve portion female thread 8FX that screws onto the expanding male thread, and a nut portion 13 that is coaxial with the sleeve portion and integrally formed at the end of the sleeve portion, the expanding male thread 9M having a pitch different from the pitch of the thread of the other rebar 4R, and the nut portion 13 having a nut portion female thread 13F that screws onto the thread of the other rebar and has the same pitch and phase as the pocket hole female thread 5F. The sleeve hole 8H of the sleeve portion 8X is formed with a sleeve portion female thread 8FX that has the same pitch and phase as the nut portion female thread 13F.

Although it is not clear, as shown in Figures 1(a) and 18(b), the expanding female thread 9F or the expanding male thread 9M has a pitch _P9F or a pitch _P9M that is larger than the pitch _P4 of the thread joint 4R of the other reinforcing bar.

Alternatively, the enlarged female screw 9F or the enlarged male screw 9M is formed with a pitch _P9F or a pitch _P9M that is smaller than the pitch _P4 of the thread joint 4R of the other reinforcing bar.

As shown in Figures 3 and 16, the outer barrel of the cap screw 5 of the main cylinder 11 has reaction force relief surfaces 11C and 11E formed on the outer surface at either end along its longitudinal direction, which act as reaction surfaces when applying the desired torque to the nut portion 13.

As shown in Figure 9, the main cylinder has a longitudinally extending slit 15 formed through which the leading edge position of the inserted rebar 4R can be seen.

A slit 16 of approximately the same shape is formed in the main tube 11 at the location opposite the slit 15.

As shown in Figure 13(b), the rebar to be friction welded can be a deformed rebar other than a threaded rebar, such as a bamboo-shaped rebar.

According to the present invention, it is possible to provide a coupler that can firmly fasten a first reinforcing bar and a second reinforcing bar in the axial direction.

10A and 10B are longitudinal sectional views and overall outline views of the state in which the secondary cylinder is moved to the left in the latter half of the reinforcing bar fastening procedure using a reinforcing bar coupler according to the present invention when P _9F = P ₄ + 2 mm. 1 is a perspective view of the end of a threaded reinforcing bar to be friction welded before and after pressure welding. FIG. FIG. Arrangement diagram of coupler components in the initial stage of fastening. A cross-sectional view of a main cylinder with a secondary cylinder attached to it, with rebar screwed into it. A diagram of measures to prevent rotational misalignment between the main and secondary cylinders before the rebar fastening procedure. A process diagram of the first half of the reinforcing bar fastening procedure using a reinforcing bar coupler after removing the sleeve body. FIG. 10 is an overall perspective view of a coupler including a main tube showing the position of the slit. FIG. 10 is an explanatory diagram showing the position and size of a paint mark. An external view of the coupler used to check the tip of the rebar. Cross-sectional view showing the procedure for screwing the secondary barrel onto the main barrel. Another design using a main cylinder made of rebars of different diameters and types friction-welded together. Fastening procedure and outline drawing after the procedure is completed (expansion). Outline drawing of another example after the procedure is completed (expansion). An external view of a coupler including a main barrel with a polyhedral central barrel. Right-hand longitudinal section and outline drawing of the secondary cylinder for the latter stage of the rebar fastening procedure. A diagram of the first half of the rebar fastening procedure using couplers with different secondary tubes. A longitudinal cross-sectional view and an overall outline view of the state in which the secondary tube is moved to the left in the latter half of the rebar fastening procedure using a coupler with a different secondary tube. A longitudinal cross-sectional view and an overall outline view of the state in which the secondary tube is moved to the right in the latter half of the rebar fastening procedure using a coupler with a different secondary tube.

The following describes in detail the coupler for deformed reinforcing bars that utilizes threaded reinforcing bars according to the present invention, based on drawings showing an embodiment of the invention. The coupler itself is used to fasten opposing threaded reinforcing bars 4L and 4R according to the location of the building, as shown in Figure 1(a). In other words, whether or not grout is used, the aim is to firmly join the reinforcing bars by utilizing the creak of the threads, which will be described later. Of course, while the coupler is intended to be applied to threaded reinforcing bars, it is also intended for friction-welded reinforcing bars, so the reinforcing bars that are friction-welded are not limited to threaded reinforcing bars; they can also be bamboo-knot reinforcing bars, which will be described later and do not exhibit threaded behavior.

The coupler 10 shown in Figures 1(a) and 1(b) connects the ends of two opposing rebars 4L and 4R, preventing loosening of the threads and creating an elongated rebar that transmits axial force. This coupler 10 comprises a main cylinder 11 to which the end of one of the rebars 4L is friction-welded, and a secondary cylinder 12 that is threadedly fitted into the opposite side of the friction-welded side of a blind hole 5H formed along the axis of the main cylinder 11. Therefore, the coupler 10 brought to the construction site is a simple two-component structure: a component (main cylinder 11 with rebar 4L) already integrated with the rebar 4L, and another component (secondary cylinder 12) that is independent of the other rebar 4R. While both are rigid metal bodies, the main cylinder 11 and secondary cylinder 12 are generally cast components for reasons that will be explained later.

On the friction welding side of the pocket hole 5H, a pocket hole female thread 5F (pitch _P5 = _P4 ) is formed into which the tip of the screw joint 4T (pitch is expressed as _P4 ; the same applies below) of the other reinforcing bar 4R screws, and on the anti-friction welding side of this pocket hole 5H, an expanded diameter female thread _9F is provided, which is concentric with the pocket hole female thread 5F but is formed with a larger diameter (expanded diameter) than the pocket hole female thread 5F and has a pitch P9F (set to _P4 + 2 _mm ) different from _P5 .

The secondary cylinder 12 includes a sleeve portion 8 having a sleeve portion male thread 8M that screws into the enlarged diameter female thread 9F, and a nut portion 13 that is coaxial with the sleeve portion 8 and integrally formed at the end of the sleeve portion 8. The sleeve portion male thread 8M meshes with the enlarged diameter female thread 9F and has a pitch _P8M (= _P9F ), and the nut portion 13 has a nut portion female thread 13F that is threaded with the thread joint 4T of the rebar 4R and has the same phase as the pitch _P5 of the pocket hole female thread 5F (pitch _P13F = _P5 ). The sleeve hole 8H of the sleeve portion 8 also has a sleeve portion female thread 8F (pitch _P8F = _P13F ) that has the same pitch and phase as the nut portion female thread 13F. Note that the sleeve hole female thread 8F may be connected to the nut portion female thread 13F as shown in FIG. 1(a). Incidentally, as described above, the respective pitches are set as P ₄ =P ₅ =P _8F =P _13F and P _8M =P _9F =P ₄ +2 mm (2 mm is an example).

The end of the rebar is the cut surface shown in Figure 2(b), but the welded portion of the rebar that was the subject of friction welding has a roughly hollow ring-shaped burr 1 as shown in Figure 2(a). The welded portion of the main tube 11 also has a roughly hollow ring-shaped burr 2 as shown in Figure 1(a), but it is generally small.

The main cylinder 11 is a cylinder with an outer diameter approximately 1.5 times that of the rebar, as shown in Figure 3. The outer shape of the left cylinder 11C, which is a part of it, forms a polygonal (hexagonal in the figure) facet for applying counter torque, making it easier to apply torque with a wrench (not shown) hooked onto the polygonal (hexagonal in the figure) facet formed on the nut portion 13 of the secondary cylinder 12, the external view of which is shown in Figure 4. Incidentally, when applying the secondary cylinder 12 to the main cylinder 11 to form a coupler, for example, when using 4R rebar of D35 (nominal diameter approximately 35 mm), the length requires at least 4 to 6 pitches of meshing at one point, and the total dimension of the main cylinder 11 and secondary cylinder 12 when combined (meshed) is approximately 200 mm at most.

Before discussing the rebar joining operation, let's briefly introduce the well-known friction welding process that takes place beforehand. This coupler differs from types that butt the ends of opposing rebars together within a cylinder and fasten them together using numerous locking screws (such as U.S. Patent No. 5,046,878, mentioned in the prior art section). Instead, the main cylinder 11 and rebar 4L press against each other where they meet, and the heat generated by their relative high-speed rotation crimps the contact area. Since this cannot be done on a construction site, it is done in a well-equipped factory after the rebar has been manufactured, based on the building design documents (blueprints), before shipping. In this way, the rebar 4R, which is much longer than the coupler, can be threaded into the coupler with a gentle rotation at the construction site, while only the secondary cylinder 12, which is much shorter and easier to handle than the rebar, can be firmly joined and locked with just a gentle rotation, followed by a strong over-rotation, as described below.

By the way, the blind hole female thread 5F and the nut portion female thread 13F are normally right-handed, but they are provided with a sufficient number of threads (for example, 4 to 6) to engage with the threads 4T of the rebar 4R (for example, the blind hole female thread 5F in Figure 1(a) is drawn with only three threads to avoid making it too long horizontally for ease of drawing), so there will be no shortage of interlocking threads even when a specified axial force is applied.

As shown in Figures 5(c) and (d), which follow Figures 5(a) and (b), the secondary tube 12 is placed facing the main tube 11 to which the rebar 4L is friction-welded. Using the paint mark 3, which was applied in advance during the temporary setting as shown in Figure 10 below, as a guide, at this point the blind hole female thread 5F, sleeve female thread 8F, and nut female thread 13F form a series of right-handed threads that are concentric and have the same pitch and phase (see Figure 5(c) in particular). Therefore, by rotating the main tube 11 to which the rebar 4L is pressure-welded or the rebar 4R, the rebar 4R, which has a right-handed thread, can be easily threaded into the coupler (see Figure 6). If a phase misalignment occurs between the main tube and the secondary tube during rotation (threading) of the rebar 4R or the main tube 11, preventing the rebar 4R from threading, a rotational misalignment prevention sleeve, as described below, can be used. This is a sleeve body 7 with a hexagonal hole portion 11D and a circular hole portion 6 connected together, as shown in Figures 7(a) and (b). It is retracted above the rebar 4R and placed over the round body portion of the main cylinder 11 and the nut portion 13 of the secondary cylinder 12, and unexpected movement can be prevented by driving a locking screw 7a into the round body portion.

When applying the paint mark 3 (see Figure 10), the number of unengaged threads between the sleeve portion male thread 8M of the sleeve portion 8 and the expanded diameter female thread 9F on the non-friction-welded side of the pocket hole 5H is set to 2 or 3, allowing for at least one pitch of left or right movement of the secondary cylinder 12. In other words, there is room for at least one pitch of right or left movement to allow for creaking (two threads are left in Figures 6, 7, 8, and 10). The above operations complete the pre-fastening process (see Figure 8).

If the reinforcing bar 4R is left screwed into the main cylinder 11, the reinforcing bar 4R will not be locked to the main cylinder 11, so the following operation is performed.
As shown in Figure 1, the male thread 8M of the sleeve of the secondary cylinder 12 has a pitch _P8M that is different from the pitch _P4 of the thread joint 4R of the rebar, and is, for example, dimensioned as _P8M = _P4 + 2 mm. The 2 mm difference is intended to allow for creaking, as well as to allow for several pitches of tolerance in the pitch formation of the rebar (for example, ±0.2 mm). It goes without saying that the female thread 5F of the blind hole is a female thread that will have the required number of engagements for fastening rebar if the forming tolerance of the thread joint pitch is allowed, taking into account the wear of the forming rolls.

As shown in Figure 9, a longitudinally extending slit 15 is formed in the outer barrel of the cap screw 5 of the main tube 11, allowing for viewing of the tip position of the inserted rebar 4R. Furthermore, if a slit 16 of approximately the same shape, shown by the dashed line, is formed opposite this slit, it is convenient for easier viewing. Therefore, by looking into the slits 15 and 16, as shown in Figure 11, it is possible to confirm that the end of the threaded rebar 4R has reached the designated position on the female thread 5F of the cap screw 5. This operation automatically confirms that the number of interlocking threads required for the joints 4 to 6 described above has been achieved. The rebar 4R is now embraced by the main tube 11, and alignment between the main tube 11 and the rebar 4R is also achieved. Then, from the position shown in Figure 8, the secondary tube 12 is rotated clockwise and moved in the direction of arrow 17 shown in Figure 1(a) to approach the main tube 11. At this time, the rebar 4R has a minimum thread engagement amount sufficient to maintain fastening force in the pocket hole female thread 5F, the sleeve female thread 8F, and the nut female thread 13F, making it possible to transmit the desired axial force.

With this configuration, a desired torque sufficient to maintain fastening strength is applied to the hexagonal nut portion 13 of the secondary cylinder 12, and the secondary cylinder 12 is over-rotated while the left barrel 11C of the main cylinder 11 generates a reaction force. This causes frictional forces (creating creaks) on the contact tooth surfaces resulting from the difference in pitch between the nut portion female thread 13F of the nut portion 13, into which the thread joint 4T of the rebar is threaded, and the sleeve portion male thread 8M of the secondary cylinder 12, preventing unintended rotation or axial displacement of the rebar. The coupler's structure makes it ideal for use in joint construction (not shown), etc.

By the way, it is not easy to match the phase of the sleeve female thread 8F, which meshes with the expanded female thread 9F of the cap screw hole in the main cylinder 11, with the phase of the nut female thread 13F through cutting (machining) operations. In other words, while cutting (molding) the threads is easy, cutting the threads while matching the phase is an extremely difficult task. To increase the reliability of this process, casting is used. The thread-like core is positioned so that the phases match, a reference wall (reference surface) that should be positive is provided (not shown), and the end is abutted against this, with not only the position but also the angular orientation determined before casting. This dramatically improves molding efficiency. This is because, as can be seen from Figure 1(a), it is necessary to ensure that all threads achieve consistent phase.

Returning to the main topic, when attempting to rotate the secondary cylinder 12, if the sleeve body 7, which connects the hexagonal hole portion 11D and the circular hole portion 6, is hung as shown in Figure 7(a), it is retracted onto the right side of the rebar 4R or removed from the opposite end of the rebar 4R, and then the secondary cylinder 12 is rotated clockwise to move leftward as shown by arrow 17 in Figure 1(a). The male thread 8M of the sleeve portion of the secondary cylinder 12 follows the enlarged female thread 9F of the main cylinder 11. Meanwhile, the female thread 13F of the nut portion also threads forward, following the thread joint 4T of the rebar 4R. However, before the sleeve male thread 8M has completed one pitch _P8M (= _P9F = _P4 +2mm) on the enlarged female thread 9F, the thread advancement of the 2mm shorter rebar 4R by one pitch is achieved, and this becomes a hindrance, and with the secondary tube 12's light rotation up to that point, the thread advancement of the sleeve male thread 8M along the enlarged female thread 9F of the main tube 11 is hindered due to the rigidity of the secondary tube 12. Therefore, if the secondary tube 12 is forcibly continued to rotate clockwise (over-rotate), the nut female thread 13F will apply a creaking torque to the thread advancement of the rebar 4R before the sleeve male thread 8M has completed one pitch on the enlarged female thread 9F. The thread 4T of the rebar 4R will damage the female thread 13 of the nut portion with which it is threaded (due to tooth surface interference), to the extent that it will not even allow reverse rotation of the secondary cylinder 12, or the female thread 13 of the nut portion will damage the thread 4T of the rebar 4R, or they will damage each other. The same is true when the secondary cylinder 12 is moved to the right 18, as shown in Figure 17(a). The same can be said when _P4 = _P5 = _P8F = _P13F and _P8M = _P9F = _P4 - 2 mm, so duplicated description will be omitted below.

A specific example will be used for a simple explanation below. Let's assume that _P8M = _P9F = 19 mm and _P4 = _P13F = 17 mm, and the secondary cylinder 12 is first rotated 1/4 turn (π/2 rad). The sleeve male thread 8M of the secondary cylinder 12 follows the expanded female thread 9F of the main cylinder 11 and moves 4.75 mm. Meanwhile, the nut female thread 13F should move 4.25 mm following the rebar 4R. The secondary cylinder 12 is capable of this leftward movement as long as the difference (4.75 - 4.25 = 0.5 mm) is within the range of the sum of the backlash on the sleeve male thread 8M side and the backlash on the nut female thread 13F side.

Suppose the secondary cylinder 12 is rotated another 1/12th of a turn to the right (a cumulative 1/3 turn from the start of the clockwise rotation, or 2π/3 rad). The male sleeve thread 8M of the secondary cylinder 12 follows the expanded female thread 9F of the main cylinder 11, moving a total of 6.33 mm. Meanwhile, the female nut thread 13F should move a total of 5.67 mm. When the difference (6.33 - 5.67 = 0.66 mm) can no longer be absorbed by the sum of the backlash on the male sleeve thread 8M side and the backlash on the female nut thread 13F side, the secondary cylinder 12 is becoming or is no longer able to move left. Light rotation of the secondary cylinder 12 is not permitted, and if torque exceeding that of the 1/12th turn just performed is applied, the male sleeve thread 8M will follow the expanded female thread 9F of the main cylinder 11, while the female nut thread 13F will generate creaking against the thread joint 4M of the rebar 4R. The greater the torque, the more deformation (roughening) occurs on the mating tooth surfaces, and the resulting creaking causes the coupler to lock. This creaking occurs on any or all of the mating thread surfaces within the coupler. Therefore, locking is achieved by gently rotating only one component (the secondary cylinder 12) followed by a strong rotation. At this time, the secondary cylinder 12 is subjected to axial tension, so it goes without saying that it must be able to withstand this axial force.

By the way, the rebar 4L that is the target of the friction welded rebar can be of a different diameter than the rebar 4R (see Figure 13(a)), or it can be the bamboo-knot rebar 4B mentioned at the beginning (see Figure 13(b)), which does not require screw-like behavior. This is convenient as it allows for variety in the rebars used, prevents excessive use of rebar material, and helps with inventory adjustments.

When threading the rebar 4R shown in Figure 12 into the main tube 11, it should be noted that if the secondary tube 12 is threaded before it is engaged, the secondary tube 12 will not be able to thread into the main tube 11 due to differences in pitch. Therefore, with the secondary tube 12 engaged with the main tube 11, a substitute for the rebar 4R (a short item approximately 300 mm long) or a replica is threaded from the secondary tube 12 into the main tube 11. This automatically achieves phase alignment. In this case, the number of unengaged threads between the sleeve male thread 8M and the enlarged female thread 9F is set to two or three, and the above-mentioned paint mark 3 (see Figure 10(a)) is applied to the boundary between the main tube 11 and the secondary tube 12. This allows the secondary tube 12 to move to the right or left by at least one pitch. Needless to say, the substitute for the rebar 4R is then removed.

Incidentally, the position of the left barrel 11C (see Figure 1(b)), which is a polygonal (hexagonal in the illustration) facet for counter torque of the main barrel 11, may be the middle barrel 11E as shown in Figure 16. It may be in a position that does not interfere with the attachment of the sleeve body 7 shown in Figure 7 or a device with the same function.

Incidentally, Figures 14 and 15 show some examples of fastening work performed on construction sites. Although the figure is small, Figure 14 shows an example of repeating (i) through (iv) from the state corresponding to Figure 1(b) to reach (v). The subscripts 1, 2, 3, etc. after the reference numerals indicate the order in which the fasteners are introduced. It goes without saying that this is not limited to this example, and it is also possible to increase the length by introducing other types of couplers in intermediate positions. Figure 15(a) is an example corresponding to Figure 13(a), and it is natural to reduce or increase the size of the coupler 10 as necessary to match the thickness of the applicable rebar. Figure 15(b) is an example corresponding to Figure 13(b).

The above description concerns the coupler 10 shown in Figures 1, 6, and 12, in which the secondary cylinder 12 is threaded into the main cylinder 11. However, we propose a different example, the secondary cylinder 12X, in Figures 18, 19, and 20, in which the secondary cylinder 12X is threaded onto the outer surface, i.e., periphery, of the main cylinder 11X.

The coupler 10X comprises a main tube 11X and a secondary tube 12X that is externally threadedly fitted thereto. The friction-welded side of a pocket hole 5H drilled along the axis of the main tube 11X has a pocket hole female thread 5F that threads onto the thread joint 4T of the other rebar 4R. The outer periphery of the main tube 11X has an enlarged male thread 9M that is concentric with the pocket hole female thread 5F but has a larger diameter than the pocket hole female thread 5F on the opposite side of the friction-welded side. The sleeve female thread 8FX of the secondary tube 12X that threads onto the enlarged male thread 9M has a pitch _P8FX that is different from the pitch _P4 of the thread joint 4R of the rebar. The fastening principle and behavior of this coupler 10X are almost the same as those of the previous example, so a repeated explanation will be omitted. However, as mentioned above, _P4 = _P5 = _P13F , and _P8FX = _P9M = _P4 + 2 mm. Alternatively, P ₄ =P ₅ =P _13F and P _8FX =P _9M =P ₄ -2 mm. It can be understood from the state in Fig. 18 that the creak lock is achieved by the left row 17X in Fig. 19 and the right row 18X in Fig. 20.

The above explanations reveal the following: The rebar to be connected is joined using simple components and can be fastened by gently rotating the easy-to-handle secondary cylinder followed by a strong rotation. If the rebar has threads within the molding tolerances, uniform fastening of the rebar can be achieved even if there is variation in the thread pitch. Because the pitches of the expanding female thread 9F and expanding male thread 9M on the coupler's main cylinder 11 and the female thread 13F of the nut portion that engages with the rebar 4 are different, the increased surface contact pressure of the threads during threading increases the frictional force acting on the thread surface. If roughness appears on the thread surface due to creaking caused by compression, further threading or retraction is prevented, and over-threaded threads will not come loose unless a reverse torque exceeding the load torque is applied.
It also prevents the need for longer couplers and stronger fastening loads to ensure perfect fastening. This reduces the burden of torque management, which is effective in preventing rattle and slippage. Furthermore, it allows for gradually increasing or decreasing the diameter of rebar depending on the application area of the building, and for changing deformed rebar from threaded joints to bamboo joints, thereby reducing the amount of rebar used and promoting the use of stock. 4R rebar, which is much longer than the coupler, can be threaded into the coupler with a gentle turn, while a strong over-turn is all it takes to firmly join and lock the rebar, using only the secondary tube, which is much shorter and easier to handle than the rebar itself. The coupler's structure also makes it ideal for use in joint construction.
Furthermore, the expanding female screw or expanding male screw has a pitch that is larger or smaller than the pitch of the thread of the reinforcing bar, and this pitch difference results in a large frictional force acting on the surface of the screw due to the surface contact pressure of the screw, resulting in a strong fastening due to the creaking between the screws.
Furthermore, if a reaction force relief surface is formed on the outer surface of the main cylinder, it becomes easier to remove the reaction force when a desired torque is applied to the nut portion.
If a slit extending in the longitudinal direction is formed in the main cylinder, the position of the tip of the inserted rebar can be confirmed. If a slit of approximately the same shape is formed at the opposite position to this slit, it can be seen through, making it easier to confirm the position of the tip of the inserted rebar.

It should be noted that there is no intention to exclude the use of grout (mortar, adhesive, thread locking agent, etc.) in combination with the present invention. In other words, this does not mean that grout or the like should not be used in the configuration of this invention, but rather that in principle, injection of grout is often not necessary, and it goes without saying that it may be used in a known manner.

1: rebar burr, 2: main tube burr, 3: paint mark, 4: rebar, 4T: screw knot, 4B: bamboo knot, 4L, 4R: screw knot rebar, 5H: blind hole, 5F: blind hole female thread, 6: circular hole portion, 7: sleeve body, 7a: set screw, 8, 8X: sleeve portion, 8H: sleeve hole, 8M: sleeve portion male thread, 8F, 8FX: sleeve portion female thread, 9F: expanding diameter female thread, 9M: expanding diameter male thread, 10.10X: coupler, 11.11X: main tube, 11C: left body, 11D: hexagonal hole portion, 11E: middle body, 12.12X: secondary tube, 13: nut portion, 13F: nut portion female thread, 15, 16: slit, 17.17X: left arrow, 18.18X: right arrow.

Claims (8)

A coupler capable of fastening a first reinforcing bar and a second reinforcing bar in an axial direction,
The coupler is
a main cylinder having one axial end to which the first reinforcing bar is friction-welded and another axial end to which an opening is provided;
a secondary cylinder that can be inserted through an opening of the main cylinder,
The main cylinder is
a first female screw portion formed on a part of the inner periphery;
a second female thread portion formed on an inner periphery closer to the other end than the first female thread portion,
The secondary cylinder is
a male screw portion formed on an outer periphery thereof and adapted to be threadedly engaged with a second female screw portion of the main cylinder;
A female screw portion formed on an inner periphery and threadedly engaging with the thread of the second reinforcing bar,
the first female screw portion of the main cylinder and the female screw portion of the sub-cylinder are configured to have the same pitch and phase;
The second female screw portion of the main cylinder and the male screw portion of the sub-cylinder are threadedly engaged with each other, and the first female screw portion of the main cylinder and the female screw portion of the sub-cylinder are threadedly engaged with the thread of the second reinforcing bar,
The thread pitch of the male thread portion of the secondary cylinder is configured to be different from the thread pitch of the second reinforcing bar.
coupler. The male thread portion of the secondary cylinder is formed with a male thread having a pitch larger than the pitch of the thread of the second reinforcing bar.
2. The coupler of claim 1 . The male thread portion of the secondary cylinder is formed with a male thread having a pitch smaller than the pitch of the thread of the second reinforcing bar.
2. The coupler of claim 1 . A coupler capable of fastening a first reinforcing bar and a second reinforcing bar in an axial direction,
The coupler is
a main cylinder having one axial end to which the first reinforcing bar is friction-welded and another axial end to which an opening is provided;
a secondary cylinder having an opening into which the primary cylinder can be inserted,
The main cylinder is
a male thread portion formed on the outer periphery;
a female screw portion formed on the inner periphery thereof,
The secondary cylinder is
a first female screw portion formed on an inner peripheral portion of the main cylinder and adapted to be threadedly engaged with a male screw portion of the main cylinder;
a second female screw portion formed on an inner peripheral portion opposite to the main tube side and adapted to screw into a thread of the second reinforcing bar;
the female screw portion of the main cylinder and the second female screw portion of the sub-cylinder are configured to have the same pitch and phase;
The male screw portion of the main cylinder and the first female screw portion of the secondary cylinder are threadedly engaged, and the female screw portion of the main cylinder and the second female screw portion of the secondary cylinder are threadedly engaged with the thread of the second reinforcing bar,
The thread pitch of the male thread portion of the main cylinder is configured to be different from the thread pitch of the second reinforcing bar.
coupler. The male thread portion of the main cylinder has a male thread with a pitch larger than the pitch of the thread of the second reinforcing bar.
5. The coupler of claim 4 . The male thread portion of the main cylinder is formed with a male thread having a pitch smaller than the pitch of the thread of the second reinforcing bar.
5. A coupler according to claim 4. a reaction force chamfering surface is formed on the outer surface of the longitudinal center portion of the main cylinder when a desired torque is applied to the sub-cylinder;
5. The coupler according to claim 1 or 4 . The first reinforcing bar and the second reinforcing bar have different nominal diameters.
5. The coupler according to claim 1 or 4 .