WO2007061240A1

WO2007061240A1 - Threaded sleeve for coupling the threaded deformed reinforcing bars

Info

Publication number: WO2007061240A1
Application number: PCT/KR2006/004958
Authority: WO
Inventors: Yong Keun Kim
Original assignee: Yong Keun Kim
Priority date: 2005-11-23
Filing date: 2006-11-23
Publication date: 2007-05-31
Also published as: KR20070054417A

Abstract

A semi-cylindrical ribbed sleeve is developed for coupling to the ribs of concrete reinforcing bars. The sleeve, consisting of at least two pieces with a female inner rib-thread, provides a mechanical coupling method to precisely mate with the ribs of the reinforcing bars. A pair of locking nuts inserted into both ends of the sleeve firmly fastens the reinforcing bars as a unified body. It is possible to firmly tighten the assembly and completely eliminate any gaps between the sleeve and the ribs of the reinforcing bars by one directional fastening operation without the use of grout or other filling materials. Therefore, the coupling operation becomes simple and fast to firmly bond the reinforcing bars. An elastic o-ring is used in a cylindrical sleeve to provide a unified body by exerting a resilient force. It is possible to pre-assemble the sleeve for easy and convenient operation at the construction site to prevent unexpected accidents. It is also possible to rotate the coupling device for bonding the reinforcing bars, even if the starting point of the rib-threads of the two reinforcing bars are not matched with each other.

Description

THREADED SLEEVE FOR COUPLING THE THREADED DEFORMED REINFORCING BARS

Technical Field

[1] The present invention relates to a mechanical device for bonding of reinforcing bars in which the ribs of the reinforcing bars are engaged with female rib-thread sleeves. More particularly, a pair of semi-cylindrical sleeves having ribs on their inner surface acting as a female thread is mated to the ribs (11) of the reinforcing bars (1, Ia). Next, a pair of nut portions (53) having a female rib-thread (51) on the inner surface is mated to the ribs (11) of the reinforcing bars (1, Ia), one at each end. Finally, the pair of socket portions (54) enclosing the pair of semi-cylindrical sleeves (2) is tightened along the longitudinal direction for locking the reinforcing bars (1, Ia) by removing the clearance. Therefore, it is easy to securely handle the joined reinforcing bars as a solid body. The invention also improves the ease of manipulation and maintenance. Background Art

[2] As shown in Figs. 45 to 47, the conventional sleeve (4z) for coupling reinforcing bars (1, Ia) has a female rib-thread (41) on its inner surface to mate with the ribs (11) of reinforcing bars (1, Ia).

[3] Due to the irregular and inaccurate pitches of the ribs (11) of reinforcing bars (1,

Ia), the conventional sleeve (4z) has larger tolerance thread pitch in order to allow coupling of reinforcing bars (1, Ia) without trouble.

[4] Because of the larger tolerance in the conventional sleeve, it is easy for the sleeve to loosen and slip out from the assembly. To solve the loosening problem, the conventional sleeve adopts a locking nut (5z) at both ends of the sleeve and the sleeve assembly is filled with grout material to eliminate the gap. However, the grout material is not strong enough to firmly bond the assembly of the sleeve and the reinforcing bars (1, Ia). Furthermore, due to the wide thread pitch of the sleeve, it requires extraordinary torque force to couple the sleeve to the reinforcing bars (1, Ia). It is also burdensome to prepare the grout material. Additionally, the locking nut (5z) is easily loosened by external vibrations. Because of the separated sleeve and two locking nuts, it is not easy to assemble and maintain the parts.

[5] The size of the locking nut is small enough to easily lose during the assembly at the construction site. This can cause unexpected accidents and deteriorate the working efficiency.

[6] Further, there are other problems associated with pre-arranged reinforcing bars.

Because there are no tolerances in the lengthwise directions, it is impossible to rotate the individual coupling device for bonding the reinforcing bar. Because the starting point of the rib-thread of most abutted ends of the reinforcing bars are not matched with each other, it is difficult to insert and fasten the sleeves to couple the reinforcing bars.

[7] Therefore, it is required to invent a new concept of sleeve for coupling the reinforcing bars, which can be easily and conveniently handled at a construction site to improve the working efficiency. Disclosure of Invention Technical Problem

[8] The purpose of the present invention is to solve the problems in the conventional devices for coupling the reinforcing bars. A pair of sleeves formed with an internal female rib-thread is provided for mating to the ribs of the reinforcing bars without excessive gaps. The pair of sleeves is overlapped over the ends of reinforcing bars, and then a set of sockets and locking nuts are inserted onto both ends for encompassing the sleeve and completely fastening the assembly of the coupling system. At this point, the sleeve is firmly tightened by an external force to firmly bond the reinforcing bars, so that the gap between the sleeve and the reinforcing bars is entirely eliminated without grout or other gap filling materials.

[9] A pre-assembled sleeve package set, which is a loosely assembled pair of sleeves and locking nuts, is prepared to easily couple the reinforcing bars at the construction site. One end of each reinforcing bar is inserted into one opening of the pre-assembled sleeve package set. The pre-assembled sleeve package set is adjusted to properly sit over the ribs of the reinforcing bars, and then the locking nuts are fastened by applying an external force. At the same time, the gap between the sleeve and the reinforcing bars is completely eliminated, without the use of grout or other filling materials, to firmly bond the sleeve and reinforcing bars. Therefore, the sleeve and reinforcing bars won't slip out, when loaded with a tensile force. Cracks in the concrete caused by decoupling of the sleeve will be prevented.

[10] If a pre-assembled cylindrical sleeve and locking nuts were used as one unified part, the coupling work of the reinforcing bars would be simple and fast to fasten the prearranged reinforcing bars. Technical Solution

[11] In order to accomplish the aforementioned purposes, the present invention provides a pair of sleeves formed with inner grooves or an internal female rib-thread for properly mating to the ribs of the reinforcing bars without gaps. The pair of nuts and sockets are also formed with an internal female rib-thread for properly mating to the ribs of the reinforcing bars without gaps. [12] A pre-assembled set of sleeve and locking nuts is prepared to insert one end of the reinforcing bars into a mouth thereof. The pre-assembled sleeve is properly mounted over the ribs of the reinforcing bars, and then applying the external force fastens the locking nuts.

[13] At this point, the gap between the sleeve and the reinforcing bars is completely eliminated by rotating the locking nut in one direction while applying a tensile load along the longitudinal direction for preventing a possible slip-out.

[14] Therefore, it has an advantage to use the pre-assembled sleeve because it is possible to firmly bond the sleeve and reinforcing bars and completely eliminate the gap between the sleeves and reinforcing bars by rotating the locking nuts.

[15] Another invention is provided in which a cylindrical sleeve includes an internal female rib-thread, which has an identical pattern of ribs as the reinforcing bars for properly mating without gaps. A pre-assembled cylindrical sleeve combined with a pair of locking nuts and sockets is also prepared as one unified part to easily couple the reinforcing bars by rotating the locking nuts. The pre-assembled cylindrical sleeve is also equipped with an elastic o-ring to prevent the locking nut from being separated from the sleeves by exerting an elastic force.

[16] Therefore, the assembly consisting of the cylindrical sleeve and the locking nuts is held together by the resilient force exerted by the o-ring. Then, one end of each reinforcing bar is inserted into each opening of the sleeve. The rib of the reinforcing bar is properly sited over the pre-assembled cylindrical sleeve.

[17] Then, the gap between the cylindrical sleeve and the reinforcing bar is eliminated by rotating the locking nut in one direction while a tensile load is applied along the longitudinal direction for preventing slip out.

[18] Still another invention is provided in which the two cylindrical sleeves include internal female rib-threads, which have identical patterns of ribs as the reinforcing bars for properly mating without gaps. A pair of locking nuts and the sockets encompassing the cylindrical sleeves are firmly bonded to the coupling assembly without rotating the pre-arranged reinforcing bars. Therefore, it is possible to firmly and promptly couple the pre-arranged reinforcing bars, which won't individually move along the axial direction.

Advantageous Effects

[19] A pair of semi-cylindrical sleeves, locking nuts and sockets of the present invention is pre-assembled to easily handle as a unified part. The sleeve and locking nuts are formed with an internal female rib-thread for properly mating to the ribs of the reinforcing bars.

[20] The ends of the reinforcing bars are inserted into the pre-assembled sleeve. Then, the locking nuts are fastened to apply the external force. [21] At this point, the gap between the semi-cylindrical sleeve and the reinforcing bars is completely eliminated by rotating the locking nut in one direction without grout or other filling materials for preventing slip-out.

[22] As a result, it has a merit to use the pre-assembled sleeve because the semi- cylindrical sleeve and reinforcing bars are firmly coupled and the gap between the semi-cylindrical sleeves and reinforcing bars is completely eliminated by rotating the locking nuts.

Brief Description of the Drawings [23] Fig. 1 is an exploded perspective view of a first embodiment of the present invention. [24] Fig. 2 is a perspective view of the assembled first embodiment of the present invention. [25] Fig. 3 is a cross-sectional view of the assembled first embodiment of the present invention. [26] Fig. 4 is an exploded perspective view of a second embodiment of the present invention. [27] Fig. 5 is a cross-sectional view of the assembled second embodiment of the present invention. [28] Fig. 6 is a partially exploded and assembled perspective view of the second embodiment of the present invention. [29] Fig. 7 is a cross-sectional view of an assembled third embodiment of the present invention. [30] Fig. 8 is an exploded perspective view of a fourth embodiment of the present invention. [31] Fig. 9 is a perspective view of the assembled fourth embodiment of the present invention. [32] Fig. 10 is a cross-sectional view of the assembled fourth embodiment of the present invention. [33] Fig. 11 is an exploded perspective view of a fifth embodiment of the present invention. [34] Fig. 12 is a perspective view of the assembled fifth embodiment of the present invention. [35] Fig. 13 is a cross-sectional view of the assembled fifth embodiment of the present invention. [36] Fig. 14 is an exploded perspective view of a sixth embodiment of the present invention. [37] Fig. 15 is a perspective view of the assembled sixth embodiment of the present invention. [38] Fig. 16 is a cross-sectional view of the assembled sixth embodiment of the present invention. [39] Fig. 17 is an exploded perspective view of a seventh embodiment of the present invention. [40] Fig. 18 is an exploded perspective view of an eighth embodiment of the present invention. [41] Fig. 19 is a perspective view of the assembled eighth embodiment of the present invention. [42] Fig. 20 is a cross-sectional view of the assembled eighth embodiment of the present invention. [43] Fig. 21 is an exploded perspective view of a ninth embodiment of the present invention. [44] Fig. 22 is a perspective view of the assembled ninth embodiment of the present invention. [45] Fig. 23 is a cross-sectional view of the assembled ninth embodiment of the present invention. [46] Fig. 24 is an exploded perspective view of a tenth embodiment of the present invention. [47] Fig. 25 is a perspective view of the assembled tenth embodiment of the present invention. [48] Fig. 26 is a cross-sectional view of the assembled tenth embodiment of the present invention. [49] Fig. 27 is an exploded perspective view of an eleventh embodiment of the present invention. [50] Fig. 28 is a perspective view of the assembled eleventh embodiment of the present invention. [51] Fig. 29 is a cross-sectional view of the assembled eleventh embodiment of the present invention. [52] Fig. 30 is an exploded perspective view of a twelfth embodiment of the present invention. [53] Fig. 31 is a perspective view of the assembled twelfth embodiment of the present invention. [54] Fig. 32 is a cross-sectional view of the assembled twelfth embodiment of the present invention. [55] Fig. 33 is an exploded perspective view of a thirteenth embodiment of the present invention. [56] Fig. 34 is a perspective view of the assembled thirteenth embodiment of the present invention.

[57] Fig. 35 is a cross-sectional view of the assembled thirteenth embodiment of the present invention.

[58] Fig. 36 is an exploded perspective view of a fourteenth embodiment of the present invention.

[59] Fig. 37 is a perspective view of the assembled fourteenth embodiment of the present invention.

[60] Fig. 38 is a cross-sectional view of the assembled fourteenth embodiment of the present invention.

[61] Fig. 39 is an exploded perspective view of a fifteenth embodiment of the present invention.

[62] Fig. 40 is a perspective view of the assembled fifteenth embodiment of the present invention.

[63] Fig. 41 is a cross-sectional view of the assembled fifteenth embodiment of the present invention.

[64] Fig. 42 is an exploded perspective view of a sixteenth embodiment of the present invention.

[65] Fig. 43 is a perspective view of the assembled sixteenth embodiment of the present invention.

[66] Fig. 44 is a cross-sectional view of the assembled sixteenth embodiment of the present invention.

[67] Fig. 45 is an exploded perspective view of the conventional coupling.

[68] Fig. 46 is a perspective view of the assembled conventional coupling.

[69] Fig. 47 is a cross-sectional view of the assembled conventional coupling.

Best Mode for Carrying Out the Invention

[70] Hereinafter, a rib-thread type sleeve for coupling reinforcing bars of the present invention will be described in detail with reference to the accompanying drawings.

[71] Referring to Figs. 1 to 3, the drawings show the exploded perspective views and a cross-sectional view of the assembled first embodiment of the present invention.

[72] According to the drawings, a pair of semi-cylindrical sleeves (2), which has a rib- thread (21) formed on its inner surface for smoothly mating to the ribs (11) of reinforcing bars (1, Ia), will be firmly coupled together by an external force. A pair of locking nuts (5) having a female rib-thread (51) formed on their inner surfaces will eliminate the gaps between the sleeve and the reinforcing bars to firmly fasten the sleeve and the reinforcing bars.

[73] The sleeve has a half-cylindrical shape with long enough length to overlap at least five ribs at each side of the reinforcing bars (1, Ia).

[74] The semi-cylindrical sleeves (2) have a rib-thread (21) formed on their inner surfaces, which has the same pattern of the ribs (11) in the reinforcing bars (1, Ia) for firmly bonding to the reinforcing bars (1, Ia) without gaps.

[75] The threaded sleeve has deeper grooves in the middle portion and chamfers (26) at both openings for easily accepting reinforcing bars (1, Ia) with bent or burred ends. The sleeve has an outer tapered surface (22) with the maximum diameter at the center and gradually decreasing diameter toward both ends.

[76] A pair of locking nuts (5) comprises a nut portion (53) integrally formed with a socket (54) oriented in the axial direction. The outer surface of the locking nut (5) has hexagonal surfaces to rotate with a turning tool, such as a spanner. The outer surface of the socket (54) has a plurality of splines (55) to increase adhesion with the concrete. The nut portion (53) has a rib-thread (51) formed on its inner surface with an identical pattern of ribs (11) as the reinforcing bars (1, Ia). The inner surface of the socket (54) has a larger internal diameter than the nut portion (53). The socket (54) is formed with a tapered inner surface (52), which has the maximum diameter at the mouth and gradually decreasing diameter along the axial direction to mate with the tapered outer surface (22) of the sleeve (2).

[77] The tapered inner surface (52) has a tapered female thread (52a) formed in it, having the same pitch as the ribs (11) of the reinforcing bars (1, Ia) for decreasing the frictional force while it is being coupled to the tapered outer surface (22) of the sleeve (2).

[78] The nut portion (53) has a chamfer (56) at the opening for smooth insertion of the reinforcing bars (1, Ia).

[79] An indicating mark (27) marked on the outer surfaces of the semi-cylindrical sleeves (2) will be lined up with an indicating mark (59) marked on the outer surfaces of the socket (54) for indicating a mating point of the female threads (21 , 51 ) of both parts while both parts are fastened.

[80] Accordingly, the coupling method and effectiveness of the first embodiment of the present invention are described as follows:

[81] A locking nut (5) is installed onto one end of each reinforcing bar (1, Ia) by inserting the nut portion first, and then both ends of the reinforcing bar (1, Ia) are butted together.

[82] Next, a pair of semi-cylindrical sleeves (2) is overlapped on both ends of the reinforcing bars (1, Ia) and the female rib-thread (21) is properly mated to the ribs of the reinforcing bar (1, Ia). Then, the socket (54) is inserted to encompass the pair of semi- cylindrical sleeves (2). A locking nut (5) is fastened to forcibly compress and couple the semi-cylindrical sleeve (2) and the reinforcing bars. [83] At the same time, the locking nut (53) pulls the reinforcing bars along the longitudinal direction against the supported point of the rib-thread to eliminate the gap between the sleeve and the reinforcing bars (1, Ia).

[84] Therefore, the sleeve and reinforcing bars won't slip out, when loaded with a tensile force. It will prevent cracks in the concrete caused by a decoupling of the sleeve.

[85] An alternative coupling method is the adoption of the pre-assembled set of semi- cylindrical sleeves (2) and locking nuts (5) for coupling the reinforcing bars.

[86] The first embodiment of the present invention has two merits as a coupling device of the reinforcing bars. It has effects of firmly coupling the semi-cylindrical sleeve (2) to the reinforcing bars, and completely eliminating the gap between the semi- cylindrical sleeve (2) and the reinforcing bars by fastening the locking nut (5).

[87] According to the first embodiment of the present invention, a rib-thread type sleeve as a coupling device for reinforcing bars comprises: a pair of semi-cylindrical sleeves (2) formed with an internal rib-thread (21) for mating to the ribs (11) of reinforcing bars (1, Ia) without a gap. The locking nuts (5) are formed with an inner tapered surface (52), which has the same slope for mating to the outer tapered surface (22) of t he semi-cylindrical sleeve (2). A pair of locking nuts (5) installed at both ends of the semi-cylindrical sleeves (2) and on the reinforcing bars will be rotated in the direction of the semi-cylindrical sleeve. The female thread (51) of the locking nut (2) will be advanced to compress the outer tapered surface (22) of the semi-cylindrical sleeves (2) to completely eliminate the gap between the semi-cylindrical sleeves (2) and the rib (11) of the reinforcing bars (1, Ia). Therefore, the semi-cylindrical sleeve (2) won't slip off the reinforcing bars due to a tensile force.

[88] In general, the conventional sleeve has larger gaps between the cylindrical sleeve and the rib of the reinforcing bars to allow easy installation of the reinforcing bars into the sleeve. The large gap between the sleeve and the reinforcing bars causes cracks in the concrete. Thus, the conventional sleeve adopts the practice of filling the sleeve assembly with grout materials to eliminate the gaps. However, the grout materials do not have enough strength to firmly bond the coupling of sleeve and reinforcing bars. It is also a burdensome task to fill the grout materials in the gaps.

[89] Fig. 4 to Fig. 5 show an exploded perspective view and a cross-sectional view of a second embodiment of the present invention.

[90] Accordingly, a basic structure of the second embodiment is identical to that of the first embodiment. A pair of locking nuts (5) has identical form and function to with those of the first embodiment.

[91] The basic structure of semi-cylindrical sleeves (2b) is identical to that of the first embodiment, except for the addition of an elastic position block (20a). A groove (24) for mounting the elastic position block (20a) is formed in the middle of the mating surfaces of each semi-cylindrical sleeve. A pair of protrusions (22b) is formed near both ends of the tapered outer surface (22) of the semi-cylindrical sleeve (2b), located for locking to the tapered inner thread (52a) of the locking nuts (5).

[92] The protrusions (22b) of the semi-cylindrical sleeves (2b) and the tapered female thread (52a) of the locking nuts (5) are used to pre-assemble the locking nut (5) and the semi-cylindrical sleeves (2b) for preparing a unified part. A tapered inner surface (52) of the locking nuts (5) has a tapered female thread (52a) formed on it to decrease the frictional force while it is contacting the tapered outer surface (22) of the semi- cylindrical sleeves (2b).

[93] The elastic position block (20a) is inserted to secure the assembly of the semi- cylindrical sleeves (2b). Therefore, it will prevent the separation of the semi- cylindrical sleeves (2b) from each other when the locking nut (5) is fastened.

[94] Accordingly, the coupling method and effectiveness of the second embodiment of the present invention are described as follows:

[95] Installing a pair of the elastic position blocks (20a) into the mounting grooves (24) of semi-cylindrical sleeves (2b),

[96] mating a pair of semi-cylindrical sleeves (2b) so the rib-threads (21) of their internal surfaces face each other, inserting and loosely assembling a pair of locking nuts (5) onto both ends of semi-cylindrical sleeves (2b),

[97] inserting an end of a reinforcing bar (1) into one end of the loosely assembled sleeves (2b) along the longitudinal direction, and inserting an end of another reinforcing bar (Ia) into the other end of the loosely assembled sleeves (2b),

[98] encompassing the pair of the semi-cylindrical sleeves (2b) by overlapping the locking nuts (5) and tightening the loosely assembled sleeves (2b) by rotating the locking nuts (5).

[99] At the same time, the socket portions (54) of the locking nuts (5) compress the semi-cylindrical sleeves (2b) from opposite directions at both ends until the gap between the semi-cylindrical sleeves (2b) and reinforcing bars (1, Ia) is completely eliminated.

[100] As seen in the drawing, the rib-thread (11) of the reinforcing bars has a trapezoidal shape. A pair of the semi-cylindrical sleeves (2b) also has the same trapezoidal shape of rib-thread (21).

[101] If the locking nuts (5) were loosely pre-assembled to the semi-cylindrical sleeves

(2b), the large tolerance is provided between the pitches of the rib-thread. Therefore, the unified part of pre-assembled semi-cylindrical sleeves (2b) can be easily installed onto the reinforcing bars (1, Ia).

[102] Because the present invention adopts two pieces of the semi-cylindrical sleeves

(2b), it is possible to combine the semi-cylindrical sleeves (2b) and reinforcing bars (1, Ia) to completely eliminate the gaps in the assembly.

[103] In the second embodiment of the present invention, a unified part can be used as a coupling device for the reinforcing bars. A semi-cylindrical sleeve (2b) that is pre- assembled to the locking nut (5) is adopts a thread-coupling method without the need for grout or other filling materials for completely eliminating the gaps and preventing slip-out.

[104] Because the thread coupling generally requires enough tolerance between the two threaded parts to reduce the frictional forces, the conventional coupling has left excessive gaps between the sleeve and the reinforcing bars (1, Ia) after completely combining the two parts.

[105] According to the second embodiment of the present invention, a coupling device is divided into two halves of the cylindrical sleeve to form a pair of semi-cylindrical sleeves (2b). The locking nuts (5) consist of a nut portion (53) and a socket portion (54). The semi-cylindrical sleeves (2b) have a female rib-thread (21) formed on their internal surfaces to mate with the reinforcing bars (1, Ia) without gaps.

[106] Due to the two pieces of the semi-cylindrical sleeves (2b), it is possible to completely eliminate the gaps without the need for grout materials between the female rib-thread (21) of the semi-cylindrical sleeves and the ribs (11) of the reinforcing bars (1, Ia) by tightening the locking nuts (5). The nut portion (54) of the locking nut (5) will be rotated to compress the semi-cylindrical sleeves and reinforcing bars. As a result, the semi-cylindrical sleeve (2) won't slip out from the reinforcing bars under a tensile force.

[107] Figs. 6 and 7 show an exploded perspective view and a cross-sectional view of a third embodiment of the present invention.

[108] Accordingly, the basic structure of the third embodiment is similar to that of the first embodiment.

[109] The basic structure of the semi-cylindrical sleeves (2b) is identical to those of the first embodiment. The locking nut (5) consists of a nut portion (53), which is separated into an inner and outer nut portion. The outer piece, a compression socket (6), is a combination of the nut portion (53) and the socket portion (54). The nut portion (53) has a female fine thread (61) formed on its inner surface. The socket portion (54) has a tapered female thread (52a) formed on its inner surface, which has wider pitch than the semi-cylindrical sleeves (2b) to provide enough tolerance for combining with each other. An inner locking nut (7) has a male fine thread (71) formed on its outer surface for mating to the female fine thread (61) of the nut portion (53). The pair of the semi- cylindrical sleeves (2b) is pre-assembled with the compression socket (6) and the inner locking nut (7). For preparing one unified part, the semi-cylindrical sleeves (2b) are glued with the female fine thread (61) of the compression socket (6) and the male fine thread (71) of the inner locking nut (7) for temporarily holding the assembly together until it is attached to the reinforcing bars (1, Ia).

[110] Accordingly, the coupling method and effectiveness of the third embodiment of the present invention is described as follows:

[111] First, preparing a unified part by gluing the male fine thread (71) of the inner locking nut (7) to the compression socket (6) to pre-assemble with the semi-cylindrical sleeves (2b) for temporarily holding the assembly together.

[112] inserting an end of a reinforcing bar (1) into one end of the loosely assembled sleeves (2b) along the longitudinal direction, and inserting an end of another reinforcing bar (Ia) into the other end of the loosely assembled sleeves (2b) by rotating in the opposite direction,

[113] tightening the pair of the compression sockets (6) until the compression sockets (6) reaches the limited positions of the tapered outer surfaces (22) of the semi-cylindrical sleeves (2b). Beyond this limited point, the inner locking nuts (7) will be pushed backward by the advance of the compression sockets (6). Because the inner rib-thread of the locking nuts (7) are engaged into the ribs (11) of the reinforcing bars (1, Ia), the reinforcing bars (1, Ia) are tensioned along the axial direction to eliminate the gaps. At the same time, the socket portions (54) will compress the semi-cylindrical sleeves (2b) to tightly couple the reinforcing bars (1, Ia).

[114] At this point, the female fine thread (61) of the compression socket (6) and the male fine thread (71) of the inner locking nut (7) have shorter pitches than the rib (11) pitch of the reinforcing bars (1, Ia), so it is possible for the compression socket (6) to compress the semi-cylindrical sleeves (2b) with a relatively smaller compression force compared to the compression force of the single rib-thread type of sleeve and locking nut.

[115] The pitch of the tapered female thread (52a) of the compression socket (6) is wider than the protrusions (22b) of the semi-cylindrical sleeves (2b), thus it is easily engaged into the inner locking nut (7) and the compression socket (6).

[116] Figs. 8 to 10 show an exploded perspective view and a cross-sectional view of a fourth embodiment of the present invention.

[117] Accordingly, the basic structure of the fourth embodiment is similar to that of the first embodiment.

[118] The basic structure of the semi-cylindrical sleeves (2c) is identical to those of the first embodiment, except for the addition of an expanding spring (20). The semi- cylindrical sleeves (2c) are longer than those of the first embodiment to provide a space for a spring mounting groove (23). The tapered outer surface (22) has a protrusion (22b) disposed upon it for engaging to a tapered female thread (52a) of the compression socket (6a), and the protrusion (22b) has narrower and shorter pitch than that of the tapered female thread (52a) of the compression socket (6a).

[119] As seen in the drawing, the fourth embodiment comprises; the locking nut (5) consisting of three portions, a socket portion (54) of the compression socket (6a), an inner o-ring groove (62) for mounting an elastic o-ring (20c) disposed at the tip of the inner locking nut (7a), a chamfer (65) at the opening of the compression socket (6a) for easily inserting the reinforcing bars, an outer o-ring groove (57a) of the inner locking nut (7 a) for mounting the elastic o-ring (20c) and matching to the inner o-ring groove (62) of the compression socket (6a), an outer locking nut (8) formed with a male fine thread (71), and an inner locking nut (7a) formed with a female fine thread (81).

[120] The locking nut (5) consists of three portions: a compression socket (6a), the inner locking nut (7a), and the outer locking nut (8) are pre-assembled as a unified part. The pre-assembly process is as follows: the inner locking nut (7a) is installed into the outer locking nut (8). The elastic o-ring (20c) is mounted into the outer o-ring groove (57a) of the inner locking nut (7a). The subassembly of the previous step is inserted into the compression socket (6a). The subassembly of the previous step is inserted into both ends of the semi-cylindrical sleeves (2c). Herein, the elastic o-ring (20c) is mounted between the inner locking nut (7a) and the compression socket (6a) for preventing idle rotation while the semi-cylindrical sleeve (2c) is installed onto the reinforcing bars.

[121] The indicating marks (72, 66, 27) marked on the outer surfaces of the inner locking nut (7a), compression socket (6a) and semi-cylindrical sleeves (2c), respectively, will be lined up to indicate when the female rib-threads (21, 51) of the semi-cylindrical sleeves (2c) and the inner locking nut (7a) are lined up as a continuous thread.

[122] Accordingly, the coupling method and effectiveness of the fourth embodiment of the present invention is described as follows:

[123] First, preparing a unified part by pre-assembling the semi-cylindrical sleeves (2c),

[124] inserting an end of a reinforcing bar (1) into one end of the pre-assembled sleeve

(2c), and inserting an end of another reinforcing bar (Ia) into the other end of the pre- assembled sleeves (2c) by rotating in the opposite direction,

[125] fastening the inner locking nuts (7a), which are installed on both ends of the reinforcing bars (1, Ia) and completely fastening the outer locking nut (8) until the compression sockets (6) reach the limited positions of the tapered outer surfaces (22) of the semi-cylindrical sleeves (2c). Beyond this limited point, the outer locking nuts (8) and the inner locking nuts (7a) will be pushed backward. Because the inner rib- thread (51) of the inner locking nuts (7a) are engaged into the ribs (11) of the reinforcing bars (1, Ia), the reinforcing bars (1, Ia) are tensioned along the axial direction to eliminate the gaps between the female rib-thread (21) of the semi- cylindrical sleeves (2c) and the ribs (11) of the reinforcing bars (1, Ia).

[126] At this point, the female fine thread (81) of the outer locking nuts (8) and the male fine thread (71) of the inner locking nuts (7 a) have shorter pitches than the rib (11) pitch of the reinforcing bars (1, Ia), thus it is possible to compress the semi-cylindrical sleeves (2c) with a relatively small compression force compared to the compression force of the single locking nut.

[127] The outer locking nuts (8) are separated from the compression socket (6a) because the compression socket (6a) will advance in the axial direction without rotating together with the mated part.

[128] Because the tapered female thread (52a) of the compression socket (6a) will reduce the frictional force with the tapered outer surface (22) of the semi-cylindrical sleeves (2c), they are easily engaged with each other.

[129] Figs. 11 to 13 show an exploded perspective view and a cross-sectional view of a fifth embodiment of the present invention.

[130] Accordingly, a basic structure of the fifth embodiment is similar to that of the first embodiment. The basic structure of the semi-cylindrical sleeves (2d) is identical to those of the first embodiment, except for the addition of an expanding spring (20). The semi-cylindrical sleeves (2d) are longer than those of the first embodiment to provide a space for a spring mounting groove (23). The tapered outer surface (22) has a guiding groove (22c) along the longitudinal direction at both ends of the semi-cylindrical sleeves (2d).

[131] Each of the semi-cylindrical sleeves (2b) has a pin (25) protruding at one side and a recess (25a) on the other side on the mating surfaces.

[132] The locking nut (5) is divided into two parts - a socket portion (54) and a compression socket (6b). The compression socket (6b) has an inner o-ring groove (62) for mounting an elastic o-ring (20c) and an inner tapered surface (52) without threads. A tap hole (64) is disposed at the middle top of the compression socket (6b). The inner locking nut (7b) has an inner o-ring groove (57a) for mounting the o-ring (20c) on a stepped down stub.

[133] A process for preparing the pre-assembled semi-cylindrical sleeves (2d) combined with the compression sockets (6a) and the inner locking nuts (7b) as one unified part is as follows: an elastic o-ring (20c) is mounted in the inner o-ring groove (57a) of the inner locking nut (7b). A pin (25) and a recess (25a) are mated to combine the pair of semi-cylindrical sleeves (2b).

[134] Herein, the elastic o-ring (20c) is mounted between the compression socket (6b) and the inner locking nut (7b) for rotating the inner locking nut (7b) and preventing idle rotation of other parts while the semi-cylindrical sleeve (2d) is installed onto the reinforcing bars. Because the mated pin (25) and recess (25a) secure the assembly of the semi-cylindrical sleeves (2b), it is easy and convenient to handle.

[135] Accordingly, the coupling method and effectiveness of the seventh embodiment of the present invention is described as follows:

[136] First, preparing a unified part to pre-assemble the semi-cylindrical sleeves (2d) for temporarily holding the assembly together.

[137] Inserting an end of one reinforcing bar (1) into one end of the pre-assembled sleeves (2d) along the longitudinal direction, and inserting an end of another reinforcing bar (Ia) into the other end of the pre-assembled sleeves (2d) by rotating in the opposite direction.

[138] Next, tightening the pair of inner locking nuts (7b) installed at both ends of the semi-cylindrical sleeves (2d) while the compression sockets (6) move along the axial direction to compress the semi-cylindrical sleeves (2d) onto the reinforcing bars (1, Ia). At this point, the inner locking nuts (7) will be pushed backward along the reinforcing bars (1, Ia). Then, the reinforcing bars (1, Ia) are tensioned along the axial direction to eliminate the gaps. Because the compression socket (6b) and the inner locking nuts (7) are separate parts, the compression socket (6b) won't rotate while the inner locking nuts (7) are fastened. It is also possible to easily compress the semi- cylindrical sleeves (2d) without large frictional resistance.

[139] Figs. 14 to 16 show an exploded perspective view and a cross-sectional view of a sixth embodiment of the present invention.

[140] According to the drawings, a basic structure of the sixth embodiment combines that of the fourth and fifth embodiments.

[141] The pair of semi-cylindrical sleeves (2d) and the compression sockets (6b) are identical to the fifth embodiment. The inner locking nuts (7 a) and outer locking nuts (8) are identical to the fourth embodiment.

[142] A process for preparing a unified part of the pre-assembled semi-cylindrical sleeves

(2d) that is combined with the compression sockets (6b) and the inner locking nuts (7a) is as follows: The inner locking nuts (7a) are combined to the outer locking nuts (8). An elastic o-ring (20c) mounted in the inner o-ring groove (57a) of the inner locking nut (7a) is inserted into the compression sockets (6b). A set of the assembled compression sockets (6b) is combined to both ends of the semi-cylindrical sleeves (2b). Finally, a locking bolt (9) is installed into the tap hole (64) at the middle top of the compression socket (6b).

[143] Accordingly, the coupling method and effectiveness of the sixth embodiment of the present invention is described as follows:

[144] First of all, preparing a unified part of the pre-assembled semi-cylindrical sleeves

(2d),

[145] inserting an end of a reinforcing bar (1) into one end of the pre-assembled sleeve

(2d), and inserting an end of another reinforcing bar (Ia) into the other end of the pre- assembled sleeves (2d) by rotating in the opposite direction, [146] fastening the inner locking nuts (7a), which are installed on both ends of the semi- cylindrical sleeves (2d) with the reinforcing bars (1, Ia) and completely fastening the outer locking nut (8) until the compression sockets (6) reach the limit positions of the tapered outer surfaces (22) of the semi-cylindrical sleeves (2d). Beyond this limit point, the outer locking nuts (8) and the inner locking nuts (7a) will be pushed backward. Because the inner rib-threads (51) of the inner locking nuts (7a) are engaged into the ribs (11) of the reinforcing bars (1, Ia), the reinforcing bars (1, Ia) are tensioned along the axial direction to eliminate the gaps between the female rib-thread (21) of the semi-cylindrical sleeves (2d) and the ribs (11) of the reinforcing bars (1, Ia).

[147] At this point, the female fine thread (81) of the outer locking nuts (8) and the male fine thread (71) of the inner locking nuts (7 a) have shorter pitches than the rib (11) pitch of the reinforcing bars (1, Ia), thus it is possible to compress the semi-cylindrical sleeves (2c) with a relatively small compression force compared to the compression force of the single locking nut.

[148] Fig. 17 shows an exploded perspective view of a seventh embodiment of the present invention.

[149] According to the drawings, a basic structure of the seventh embodiment is similar to that of the first embodiment. The basic structure of the locking nut (5) is identical to that of the first embodiment.

[150] The cylindrical sleeve is divided into three pieces to form the segment sleeves (3).

Each segment sleeve (3) has a female rib thread (31) formed on its inner surface, which has an identical pattern to that of the ribs (11) of the reinforcing bars (1, Ia) for completely eliminating the gaps between the female rib thread (31) and reinforcing bars (1, Ia). A chamfer (34) is disposed at the opening of the sleeve for smoothly inserting the reinforcing bars along the axial direction.

[151] A spring mounting groove (33) is formed in the middle of the female rib-thread (31) along the longitudinal direction of the segment sleeves (3) for mounting an expanding spring (20). The segment sleeves (3) are formed with a tapered outer surface (32), of which the diameter gradually decreases along the axial direction from the center toward both ends.

[152] A tapered male thread (32a) formed on the tapered outer surface (32) of the segment sleeves (3) has the same pattern as a tapered female thread (52a) of the locking nut (5). Because the segment sleeves (3) consist of three pieces, it is easy and convenient to wrap and compress the large diameter of the reinforcing bars.

[153] Accordingly, the coupling method and effectiveness of the seventh embodiment of the present invention is described as follows:

[154] First, an expanding spring (20) is mounted in the spring mounting groove (33). Then, a unified part is prepared by loosely pre-assembling the three segment sleeves (3) and locking nuts (5) for temporarily holding the assembly together.

[155] An end of a reinforcing bar (1) is inserted into one end of the pre-assembled segment sleeve (3), and an end of another reinforcing bar (Ia) is inserted into the other end of the pre-assembled segment sleeves (3) by rotating in the opposite direction.

[156] The pair of locking nuts (5), which are installed on both ends of the segment sleeves

(3) with the reinforcing bars (1, Ia), are tightened. Then, the socket portions (54) of the locking nuts (5) compress the segment sleeves (3) to eliminate the gaps between the female rib-thread (31) of the segment sleeves (3) and the ribs (11) of the reinforcing bars (1, Ia).

[157] Figs. 18 to 20 show an exploded perspective view and a cross-sectional view of an eighth embodiment of the present invention.

[158] According to the drawings, the device of the present embodiment for coupling reinforcing bars (1, Ia) comprises a piece of cylindrical sleeve (4b), a pair of locking nuts (5c) and an elastic o-ring (20c).

[159] The single piece of cylindrical sleeve (4b) has a female rib-thread (41) formed on its inner surface, which has the same pitch pattern as the ribs (11) of the reinforcing bars (1, Ia) to be coupled.

[160] An inner coupling portion (42) of increased inner diameter is disposed at both openings of the cylindrical sleeve (4b). The diameter of the inner coupling portion (42) is larger than that of the female thread portion (41) of the cylindrical sleeve (4b). An inner o-ring groove (42a) for mounting an elastic o-ring (20c) is formed on the inner coupling portion (42). A chamfer (46) is disposed at the opening of the cylindrical sleeve (4b) for easily inserting the reinforcing bars.

[161] The locking nut (5c) is formed with an outer coupling portion (57) of reduced diameter, which has a smaller diameter than that of the locking nut (5c). The outer surface of the cylindrical sleeve (4b) has a hexagonal surface (45) at the center for spinning by a turning tool, such as a spanner. A hole (44) located at top center is for filling the sleeve with grout materials.

[162] The locking nut (5c) has a female rib-thread (51) formed on its internal surface, which has the same pitch pattern as the ribs (11) of the reinforcing bars (1, Ia). An outer coupling portion (57) having a reduced diameter is disposed along the axial direction adjacent to the locking nut (5c). An outer o-ring groove (57a) for mounting an elastic o-ring (20c) is mated to the inner o-ring groove (42a) formed on the inner coupling portion (42) of the cylindrical sleeve (4b) when the parts are completely assembled. A chamfer (56) is disposed at the opening of the locking nuts (5c) for smoothly inserting the reinforcing bars. The outer surface of the locking nuts (5c) has hexagonal surfaces for spinning by a turning tool such as a spanner. [163] An indicating mark (59) marked on the outer surfaces of the locking nuts (5c) will be lined up to the indicating marks (40) marked on both sides of the outer surfaces of the cylindrical sleeve (4b) when the female threads (41, 51) of both parts are lined up. [164] The elastic o-ring (20c) is mounted in the inner o-ring groove (42a) of the cylindrical sleeve (4b) and the outer o-ring groove (57a) of the locking nut (5c). [165] The eighth embodiment of the present invention has three core actions. The first is that the cylindrical sleeve (4b) and the locking nuts (5c) are tightly combined as a unified piece by the resilient force. [166] Second, the pre-assembled cylindrical sleeve (4b) and locking nuts (5c) act as a unified part when threaded to the reinforcing bars (1, Ia). However, after the pre- assembled sleeve is completely coupled to the reinforcing bars (1, Ia), the locking nut

(5c) can be rotated alone. [167] Third, the resilient force acts to prevent the pre-assembled cylindrical sleeve (4b) and the locking nuts (5c) from coming apart from each other. [168] Accordingly, the coupling method and effectiveness of the eighth embodiment of the present invention is described as follows: [169] First, a unified part is prepared, in which the inner coupling portion (42) of the cylindrical sleeve (4b) is inserted into the outer coupling portion (57) of the locking nut

(5c), then the indicating marks (59, 40) are aligned. [170] An end of a reinforcing bar (1) is inserted into one end of the pre-assembled sleeve

(2d), and an end of another reinforcing bars (Ia) is inserted into the other end of the pre-assembled sleeve (2d) by rotating in the opposite direction. [171] The locking nut (5c) is completely fastened by a turning tool until the gaps between the cylindrical sleeve (4b) and the reinforcing bars (1, Ia) are eliminated. [172] Because the cylindrical sleeve (4b) and the locking nuts (5c) are pre-assembled as a unified part by the resilient force, it makes the task simple and easy at the construction site. Therefore, it has a merit to reduce the construction cost. [173] Figs. 21 to 23 show an exploded perspective view and a cross-sectional view of a ninth embodiment of the present invention. [174] According to the drawings, a basic structure of the ninth embodiment is similar to that of the eighth embodiment. [175] A restricting ring (57c) is disposed at a tip of the stepped coupling portion (57) of the locking nut (5b). [176] A coupling portion (42) of increased diameter, which has a larger diameter than the female rib-thread (41), is disposed at both ends of the cylindrical sleeve (4a) at the o penings thereof. [177] A fastening bolt (9a) is installed through a tap hole (42c), which passes through the coupling portion (42), for fastening the cylindrical sleeve (4) to the locking nut (5b). [178] An elastic o-ring (20b), which is the same as that of the eighth embodiment, is installed inside of the stepped coupling portion (42) of the cylindrical sleeve (4a) for exerting the elastic force. Because the cylindrical sleeve (4a) is pre-assembled to the locking nut (5b) and the fastening bolt (9a) and elastic O-ring (20b) are installed, the pre-assembly won't be rotated by a weak force. While the pre-assembled part is engaged to the reinforcing bars (1, Ia), the pre-assembled cylindrical sleeve (4a) and the locking nut (5b) are rotated together. After the pre-assembled part is completely engaged to the reinforcing bars, the locking nut (5b) is rotated alone.

[179] Accordingly, the coupling method and effectiveness of the ninth embodiment of the present invention is described as follows:

[180] First, a unified part is prepared, in which both sides of the stepped inner coupling portion (42) of the cylindrical sleeve (4a) are pre-assembled to the stepped outer coupling portions (57) of the locking nuts (5b), then the indicating marks (40, 59) are aligned. Then, a fastening bolt (9a) is loosely fastened through a tap hole (42c) to temporarily hold the cylindrical sleeve (4a) and the locking nuts (5b).

[181] An end of a reinforcing bar ( 1 ) is inserted into one end of the pre-assembled sleeve

(4a), and an end of another reinforcing bar (Ia) is inserted into the other end of the pre- assembled sleeves (4a) by rotating in the opposite direction.

[182] The locking nut (5b) is completely tightened by a turning tool until the gaps between the cylindrical sleeve (4a) and the reinforcing bars (1, Ia) are eliminated. The grout materials may be injected to fill the gaps between the cylindrical sleeve (4a) and the reinforcing bars (1, Ia).

[183] A unified part is prepared in which the cylindrical sleeve (4a) is pre-assembled with the locking nut (5b) by a resilient force. Thus, it is possible to reduce the construction cost because it makes the task simple and easy at the construction site.

[184] Figs. 24 to 26 show an exploded perspective view and a cross-sectional view of a tenth embodiment of the present invention.

[185] According to the drawings, a basic structure of the tenth embodiment is similar to that of the eighth embodiment. The structure of the locking nut (5c) is the same as that of the eighth embodiment.

[186] An elastic spherical element (2Oe) is added into the tap hole (42c), which is disposed at the matching position of the stepped coupling portion (42) of the cylindrical sleeve (4c) and the outer o-ring groove (57a) of the locking nut (5c). Therefore, it is possible to control the fastening strength of the cylindrical sleeve (4c) and the locking nut (5c).

[187] The coupling method of the tenth embodiment is the same as that of the eighth embodiment.

[188] Figs. 27 to 29 show an exploded perspective view and a cross-sectional view of an eleventh embodiment of the present invention. [189] According to the drawings, a basic structure of the eleventh embodiment is similar to that of the eighth embodiment. [190] A stepped coupling portion (43) of reduced diameter is formed at both ends of the cylindrical sleeve (4e). An o-ring groove (43a) for mounting an elastic o-ring (20c) is formed in the middle of the stepped coupling portion (43). [191] A stepped coupling portion (58) of increased diameter is formed adjacent to the locking nut (5e). An inner o-ring groove (58a) for mounting an o-ring (20c) is formed at the middle of the coupling portion (58) of the locking nut (5e). [192] When the stepped coupling portion (58) of the locking nut (5e) is completely inserted into the outer coupling portion (43) of the cylindrical sleeve (4e), the inner o- ring groove (58 a) is matched to the o-ring groove (43 a). [193] A chamfer (56) is disposed at the edge of the locking nut for smoothly inserting the reinforcing bars. [194] Therefore, the o-ring (20c) located between the cylindrical sleeve (4e) and the locking nut (5e) exerts a resilient force to bond them as a unified part. [195] The coupling method and effect of the eleventh embodiment is same as that of the eighth embodiment. [196] Figs. 30 to 32 show an exploded perspective view and a cross-sectional view of a twelfth embodiment of the present invention. [197] According to the drawings, a basic structure of the twelfth embodiment is similar to that of the eighth embodiment. The structure of the cylindrical sleeve (4b) is the same as that of the eighth embodiment.

[198] The locking nut is divided into an inner part and an outer part.

[199] A male thread (71) is formed on the outer surface of an inner locking nut (7c).

[200] An inner o-ring groove (57a) for mounting the elastic o-ring (29c) is disposed in the middle of the stepped coupling portion (57) on the outer surface of the inner locking nut (7c). [201] A female thread (81) is formed on the inner surface of an outer locking nut (8a) for mating to the male thread (71) of the inner locking nut (7c). [202] An indicating mark (72) marked on the outer surfaces of the inner locking nuts (7c) will be aligned with the indicating marks (27) marked on both sides of the outer surfaces of the cylindrical sleeve (4b) when the female threads (41, 51) of both parts are aligned. [203] Accordingly, the coupling method and effectiveness of the twelfth embodiment of the present invention is described as follows: [204] A unified part is prepared in which the inner locking nut (7c) is engaged to the outer locking nut (8a) of the locking nut (5c), then an elastic o-ring (29c) is inserted into the inner o-ring groove (57a) of the inner locking nut (7c).

[205] An end of a reinforcing bar (1) is inserted into one end of the cylindrical sleeve

(4b), and an end of another reinforcing bar (Ia) is inserted into the other end of the cylindrical sleeve (4b) by rotating in the opposite direction.

[206] The inner locking nut (7c) installed on both ends of the cylindrical sleeve (4b) and the reinforcing bars (1, Ia) is completely fastened to pull the reinforcing bars together along the axial direction. As the outer locking nut (8a) is tightened, the inner locking nut (7c) will be pushed backward along the axial direction.

[207] At this point, because the female rib-thread (51) of the inner locking nut (7c) is engaged to the ribs (11) of the reinforcing bars (1, Ia), the reinforcing bars (1, Ia) are pulled along the axial direction to eliminate the gaps between the cylindrical sleeve (4b) and the reinforcing bars. Additionally, grout materials may be injected to close the gaps.

[208] The pitches of the female thread (81) of the outer locking nut (8a) and the male thread (71) of the inner locking nut (7c) are smaller than that of the ribs (11) of the reinforcing bars (1, Ia), thus it will be coupled stronger than the single locking nut and sleeve.

[209] Figs. 33 to 35 show an exploded perspective view and a cross-sectional view of a thirteenth embodiment of the present invention.

[210] According to the drawings, a basic structure of the thirteenth embodiment is similar to that of the eighth embodiment.

[211] An o-ring groove (57a) is formed in the middle of the outer surface of the stepped coupling portion (57) of the locking nut (5c).

[212] A spring mounting groove (42d), which is cut out through the wall, is formed at both ends of the cylindrical sleeve (4s) for inserting a clamp-spring (9n).

[213] The clamp-spring (9n) has an arch shape with two small rings at both ends to clamp the outer periphery of the cylindrical sleeve (4s). When the clamp-spring (9n) is installed over the assembly of the cylindrical sleeve (4s) and the locking nut (5c), the small ring of the clamp-spring (9n) is passed through the spring mounting groove (42d) to rest on the o-ring groove (57a) of the locking nut (5c). Thus, the clamp-spring (9n) exerts a resilient force to bond the cylindrical sleeve (4s) and the locking nuts (5c).

[214] Accordingly, the coupling method and effectiveness of the thirteenth embodiment of the present invention is described as follows:

[215] A unified part is prepared, in which the locking nuts (5c) are installed to both sides of the cylindrical sleeve (4s), then the clamp-springs (9n) are mounted.

[216] An end of a reinforcing bar (1) is inserted into one end of the pre-assembled sleeve

(4s), and an end of another reinforcing bar (Ia) is inserted into the other end of the pre- assembled sleeve (4s) by rotating in the opposite direction. [217] The locking nut (5c) is completely fastened by a turning tool until the gaps between the cylindrical sleeve (4s) and the reinforcing bars (1, Ia) are eliminated. The grout materials may be injected to fill the gaps between the cylindrical sleeve (4b) and the reinforcing bars (1, Ia) through the injecting hole (44).

[218] Figs. 36 to 38 show an exploded perspective view and a cross-sectional view of a fourteenth embodiment of the present invention.

[219] According to the drawing, a basic structure of the fourteenth embodiment is similar to that of the eighth embodiment with the addition of an intermediate stopper (9b).

[220] The cylindrical sleeve (4g) has a rib-thread (41) formed on its inner surface, which has the same pitch pattern as the ribs (11) of the reinforcing bars (1, Ia). A chamfer (46) is disposed at the mouth of the cylindrical sleeve (4g) for easily inserting the reinforcing bars (1, Ia). A hexagonal surface (45) is disposed in the middle of the outer surface of the cylindrical sleeve (4g) for a turning tool such as a spanner. A hole (44) is located on the top center of the hexagonal surface (45) for injecting the grout materials.

[221] The intermediate stopper (9b) has a rib-thread (91) formed on the circumferential surface, which has the same rib (11) pattern as the reinforcing bars (1, Ia). The shape of the intermediate stopper (9b) is similar to a short setscrew, with semi-spherical convex lateral surfaces (94) and a hex key recess (95) on one end.

[222] The intermediate stopper (9b) located at the center of the cylindrical sleeve (4g) can be installed together when the pre-assembly part is prepared, or separately installed later on.

[223] Accordingly, the coupling method and effectiveness of the fourteenth embodiment of the present invention is described as follows:

[224] The intermediate stopper (9b) is installed in the center of the cylindrical sleeve (4g).

[225] An end of a reinforcing bar (1) is inserted into one end of the pre-assembled sleeve

(4g), and an end of another reinforcing bar (Ia) is inserted into the other end of the pre- assembled sleeve (4g) until both ends of the reinforcing bars (1, Ia) meet the intermediate stopper (9b) by rotating in opposite directions.

[226] As both ends of the reinforcing bars (1, Ia) come in contact with the intermediate stopper (9b), they push against each other until the gaps between the cylindrical sleeve (4g) and the reinforcing bars (1, Ia) are eliminated. The grout materials may be injected to fill the gaps between the cylindrical sleeve (4g) and the reinforcing bars (1, Ia) through the injecting hole (44).

[227] Figs. 39 to 41 show an exploded perspective view and a cross-sectional view of a fifteenth embodiment of the present invention.

[228] According to the presented drawing, the fifteenth embodiment comprises an inner si eeve (100), an outer sleeve (100a) and a coupling socket (200) for coupling both sleeves. [229] Both sleeves (100, 100a) are installed on the ends of reinforcing bars (1, Ia), then a coupling socket (200) is coupled over both sleeves (100, 100a).

[230] The inner sleeve (100) has a female rib-thread (101) formed on its inner surface, which has the same pitch pattern as the ribs (11) of the reinforcing bars (1, Ia). The outer sleeve (100a) has a female rib-thread (101) formed on its inner surface, which has the same pitch pattern as the ribs (11) of the reinforcing bars (1, Ia), and a hexagonal head (104) at one end for turning by a tool and a male thread (103) on its outer surface.

[231] The inner sleeve (100) is inserted inside of the coupling socket (200). The outer sleeve (100a) is threaded to the coupling socket (200).

[232] The coupling socket (200) is formed with a collar (201) at its outer end for captivating the inner sleeve (100), and a female fine thread (203) at its inner mouth for engaging with the fine male thread (103) of the outer sleeve (100a).

[233] Accordingly, the coupling method and effectiveness of the fifteenth embodiment of the present invention is described as follows:

[234] A coupling socket (200) is inserted onto an end of a reinforcing bar (1). Next, an inner sleeve (100) is threaded onto the same reinforcing bar (1) until the end of the inner sleeve (100) is one thread beyond the end of the reinforcing bar (1). An outer sleeve (100a) is inserted onto the end of the other reinforcing bar (Ia).

[235] Then, the coupling socket (200) is engaged to the outer sleeve (100a) by aligning both reinforcing bars (1, Ia). As the coupling socket (200) is rotated the outer sleeve (100a) approaches the inner sleeve (100). The coupling socket (200) is continuously tightened until the gaps between the reinforcing bars (1, Ia) are eliminated.

[236] The fifteenth embodiment can be easily applied to the pre-arranged reinforcing bars at the construction site. Because the pre-arranged reinforcing bars are already fixed, they won't move in the axial direction. Therefore, the present device can be inserted to couple the reinforcing bars by threading the ribs to ribs, and it is also possible to couple the reinforcing bars, even though the starting thread of the reinforcing bars are not matched to each other.

[237] Figs. 42 to 44 show an exploded perspective view and a cross-sectional view of a sixteenth embodiment of the present invention.

[238] According to the drawing, a basic structure of the sixteenth embodiment is similar to that of the fifteenth embodiment excluding two sleeves (100b, 100c), a coupling socket (200a), a male gap adjuster (300) and a female gap adjuster (400).

[239] An inner sleeve (100b) is formed with a female rib-thread (101), which has the same pitch pattern as the ribs (11) of the reinforcing bars. The inner sleeve (100b) is also formed with a front restrictor (105) at its mouth, which has a reduced diameter, and a center restrictor (106) at the center top of its outer surface, which has an increased diameter.

[240] An outer sleeve (100c) is formed with a female rib-thread (101), which has the same pitch pattern as the ribs (11) of the reinforcing bars. The outer sleeve (100c) is also formed with a front restrictor (105) at its mouth, and a male fine thread (103) on its outer surface.

[241] A coupling socket (200a) is formed with an inner end restrictor (201) at its end, which has a reduced inner diameter, for mating to the end of the inner sleeve (100b). The coupling socket (200a) also forms an inner center restrictor (202) at a quarter of its length, which has a reduced inner diameter. The coupling socket (200a) is further formed with a female fine thread (203) on the front half of the inner surface for mating to the male thread (101) of the outer sleeve (100c).

[242] A male stopper (300) forms a short rod shape with a stepped front restrictor (301) to contact with the front restrictor (105) of the inner sleeve (100b). The male stopper (300) has a stepped outer diameter. However, the largest outer diameter is slightly smaller than the inner diameter of the inner sleeve (100b) for smoothly inserting therethrough. The male stopper contacts one end of the reinforcing bars (1, Ia) at one of the rear surfaces, and has a convex portion (302) of trapezoidal cross-section at its front surface.

[243] A female stopper (400) forms a short rod shape with a stepped rear restrictor (401) to contact the front restrictor (105) of the outer sleeve (100c). The female stopper (400) has a stepped outer diameter. However, the largest outer diameter is slightly smaller than the inner diameter of the outer sleeve (100c) for smoothly inserting therethrough. The female stopper contacts an end of the reinforcing bars (1, Ia) at one of the rear surfaces, and has a concave portion (402) with a trapezoidal cross-section at its front surface, which is guided to mate with the convex portion (302) of the male stopper (300)

[244] Accordingly, the coupling method and effectiveness of the sixteenth embodiment of the present invention is described as follows:

[245] A coupling socket (200a) is inserted onto an end of a reinforcing bar (1).

[246] A male stopper (300) is inserted into the inner sleeve (100b) with the convex portion (302) pointing away from the reinforcing bar. Then, the inner sleeve (100b) is completely threaded onto the reinforcing bar (1). When the inner sleeve (100b) is completely fastened, the gaps are eliminated between the inner sleeve (100b) and the reinforcing bar (1).

[247] A female stopper (400) is inserted into the outer sleeve (100c) with the concave portion (402) pointing away from the reinforcing bar. Then, the outer sleeve (100c) is tightly threaded onto the other reinforcing bar (Ia). When the outer sleeve (100c) is completely fastened, the gaps are eliminated between the outer sleeve (100c) and the reinforcing bar (Ia).

[248] Next, the inner sleeve (100b) and the outer sleeve (100c), which are installed on the reinforcing bars (1, Ia) are aligned to combine the two parts together. The convex portion (302) of the male stopper (300) is guided into the concave portion (402) of the female stopper (400). The inner sleeve (100b) is inserted into the coupling socket (200a). The outer sleeve (100c) is threaded to the coupling socket (200a), and as the outer sleeve (100c) is completely threaded to the coupling socket (200a), the gaps between both sleeves (100b, 100c) and the reinforcing bars (1, Ia) are eliminated.

[249] The sixteenth embodiment can be easily applied to the pre-arranged reinforcing bars that won't move in the axial direction.

Claims

[1] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a pair of semi-cylindrical sleeves (2) with a rib-thread (21) formed on the inner surface acting as a female thread for mating to the ribs (11) of reinforcing bars

(1, Ia), a pair of nut portions (53) having a female rib-thread (51) formed on the inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), and a pair of socket portions (54) for encompassing said pair of semi-cylindrical sleeves (2) along the longitudinal direction as a locking means, said socket portions (54) being integrally formed with the nut portions (53).

[2] A rib-thread type sleeve as claimed in claim 1, wherein said semi-cylindrical sleeves (22) have tapered outer surfaces, which have the maximum diameter at the center and gradually decreasing diameter toward both ends, said socket portions (54) having identical slopes of the tapered inner surfaces for mating with said semi-cylindrical sleeves (22).

[3] A rib-thread type sleeve as claimed in claim 2, wherein said pair of socket portions (54) are integrally formed with said pair of locking nuts (5), and the inner surface of the socket portions (54) have identical slopes of taper (52a) for encompassing the semi-cylindrical sleeves (2), said socket portions (54) having an identical rib-thread for mating to the ribs (11) of reinforcing bars (1, Ia).

[4] A rib-thread type sleeve as claimed in claim 3, wherein said pair of semi- cylindrical sleeves (2b) has a pair of grooves (24) in the middle of their mating surfaces for inserting position blocks (20a), and a protrusion (22b) formed near both ends of the tapered outer surfaces of the semi-cylindrical sleeves (22) for locking with the tapered inner thread (52a) of the socket portions (54).

[5] A rib-thread type sleeve as claimed in claim 1 or claim 2 or claim 3 or claim 4, wherein a set of indicating marks (27, 59) are located along the longitudinal direction on the outer surface of the semi-cylindrical sleeves (2b) and socket portions (54), and the female rib-thread (21) on the inner surface of the semi- cylindrical sleeves (2) is identically formed to mate with the ribs (11) of the reinforcing bars (1, Ia).

[6] A method for coupling reinforcing bars by using a rib-thread type sleeve, the method comprising the steps of: overlapping a pair of semi-cylindrical sleeves (2) to face a female rib-thread (21), inserting and loosely assembling a pair of nut portions (53) into both ends of the semi-cylindrical sleeves (2), inserting an end of reinforcing bars (1) into one end of the loosely assembled sleeves (2) along the longitudinal direction, so that one end portion of the reinforcing bar is located inside of the assembled sleeves (2), inserting the end of another reinforcing bar (Ia) into the other end of the loosely assembled sleeves (2) along the opposite longitudinal direction, so that the end portion of the other reinforcing bar is located inside of the assembled sleeves (2), encompassing the pair of semi-cylindrical sleeves (2) by overlapping a pair of socket portions (54) of the nut portions (53) along the longitudinal direction, and tightening the loosely assembled sleeves (2) by rotating the nut portions (53) in opposite directions from each other until any gap between the reinforcing bars (1, Ia) is completely eliminated to form a unified body.

[7] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a pair of semi-cylindrical sleeves (2) having a female rib-thread (21) formed on their inner surface to mate with ribs (11) of reinforcing bars (1, Ia), and having outer surfaces that are tapered in the manner of maximum diameter in the center and gradually decreasing toward both ends, a pair of nut portions (53) having a female rib-thread (51) formed on the inner surfaces for mating to the ribs (11) of reinforcing bars (1, Ia), and a pair of socket portions (54) with tapered inner surfaces in the manner of maximum diameter in the center and gradually decreasing toward both ends for mating with the outer surface of the semi-cylindrical sleeves (2).

[8] A rib-thread type sleeve as claimed in claim 7, further comprising a protrusion

(22b) on the tapered outer surfaces of the semi-cylindrical sleeves (2b) for locking to the socket (6), and an intermediate coupling (7) having a regular male fine-thread (71) on its outer surface and a regular female fine-thread (61) inside of the nut portions (53) for threading to the regular male fine-thread (71) of the intermediate coupling (7).

[9] A rib-thread type sleeve as claimed in claim 7, further comprising a spring mounting groove (23) for mounting an expanding spring (20) in a female thread (21) of the semi-cylindrical sleeves (2b), a guiding groove (22c) disposed longitudinally on both ends of the outer surface of the semi-cylindrical sleeves (2b), a pin (25) protruding at one side and a recess (25a) on the other side of the mating surface for mating with each other to easily assemble the semi-cylindrical sleeves (2b), an o-ring groove (62) formed inside the tip of the compressing socket (6b) for installing an o-ring (20c), a tapped hole (64) located in the middle of the socket for inserting a locking bolt (9) and an outer spring mounting groove (57a) for mounting a spring (20c) on a short cylindrical portion adjacent to the locking nut (7b).

[10] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a pair of semi-cylindrical sleeves (2) having a female rib-thread (21) formed on their inner surfaces to mate with the ribs (11) of reinforcing bars (1, Ia), a spring mounting groove (23) for mounting an expanding spring (20) on the female thread (21) of the semi-cylindrical sleeves (2b), the outer surfaces of the semi- cylindrical sleeves (2) being tapered in the manner of maximum diameter in the center and gradually decreasing toward both ends, a pair of locking nuts (7a) having a female rib-thread (51) formed for mating to the ribs (11) of reinforcing bars (1, Ia), an inner o-ring groove (57a) for mounting an elastic o-ring (20c) and a male thread (71) on the inner surface, an outer locking nut (8) having a female thread (81) formed on the inside surface for mating to the male thread (71) of the locking nuts (7 a), and a pair of compressing sockets (6a) having an inner o-ring groove (62) for installing an elastic o-ring (20c) and a tapered inner surface which has the maximum diameter in the center and gradually decreasing diameter toward both ends.

[11] A rib-thread type sleeve as claimed in claim 10, further comprising a protrusion

(22b) on the tapered outer surfaces of the semi-cylindrical sleeves (2b), and an inside surface of the compressing socket (6a) formed with a tapered female rib- thread (52a) having identical pitches as the ribs (11) of the reinforcing bars (1, Ia).

[12] A rib-thread type sleeve as claimed in claim 10, further comprising a guiding groove (22c) disposed longitudinally on both ends of the outer surface of the semi-cylindrical sleeves (2b), a pin (25) protruding at one side and a recess (25a) on the other side of their mating surfaces for mating with each other to easily assemble the semi-cylindrical sleeves (2b), and a tapped hole (64) located in the middle of the socket for inserting a locking bolt (9).

[13] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a pair of semi-cylindrical sleeves (2) formed in three segments, the inner surface having a female rib-thread (31) to mate with ribs (11) of reinforcing bars (1, Ia), the outer surfaces of the semi-cylindrical sleeves (2) being tapered such that the maximum diameter is in the center and the diameter gradually decreases towards both ends, a pair of locking nuts (53) having a female rib-thread (31) formed on the inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), and an inner surface of the socket (54) tapered such that the maximum diameter is in the center and the diameter gradually decreases towards both ends.

[14] A rib-thread type sleeve as claimed in claim 13, further comprising a female rib- thread (31) on the segment sleeves (3) forming an identical pattern to the ribs (11) of the reinforcing bars (1, Ia), a spring mounting groove (33) formed in the middle of the female rib-thread (31) in the longitudinal direction for mounting an expanding spring (20), a tapered male thread (32a) formed on the outer surface of the segment sleeves (3) to mate with a tapered female thread (52a) of the locking nut (5), said tapered female thread (52a) being formed on the inside surface of the socket (54), and a set of indicating marks (35, 59) disposed on the outer surfaces of the segment sleeves (3) and the locking nut (5).

[15] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a cylindrical sleeve (4) having a rib-thread (41) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), a pair of locking nuts (5c) having a female rib-thread (51) formed on their inner surfaces for mating to the ribs (11) of the reinforcing bars (1, Ia), and a means for bonding said cylindrical sleeve (4) and said pair of locking nuts (5c) into a unified body along the longitudinal direction.

[16] A rib-thread type sleeve as claimed in claim 15, further comprising a female thread portion (41) disposed on an inner stepped portion (42) at both ends, which has a larger diameter than that of the cylindrical sleeve (4), and locking nuts having a stepped thread portion (57), which has a smaller diameter than that of the locking nut for engaging to the female thread (41) of the inner stepped portion (42) of the cylindrical sleeve (4).

[17] A rib-thread type sleeve as claimed in claim 15, further comprising a tapped hole

(42c) on the cylindrical sleeve (4a) for installing a fastening bolt (9a), a circular elastic ring (20b) installed inside stepped portion (42) of the cylindrical sleeve (4a) for exerting an elastic force to the locking nut (5b), a restricting ring (57c) disposed at a tip of the stepped portion (57) of the locking nut (5b) for preventing the circular elastic ring (20b) from slipping out from the cylindrical sleeve (4), and said fastening bolt (9a) restricting the circular elastic ring (20b) inside the cylindrical sleeve (4).

[18] A rib-thread type sleeve as claimed in claim 16, further comprising an o-ring groove (57a) formed on an outer surface of the stepped portion (57) of the locking nut (5c) for inserting an elastic o-ring (20c), and an inner o-ring groove (42a) formed inside the stepped portion (42) of the cylindrical sleeve (4b) for inserting the o-ring (20c), so that a resilient force is exerted on the locking nut (5c).

[19] A rib-thread type sleeve as claimed in claim 16, further comprising an o-ring groove (57a) formed on an outer surface of the stepped portion (57) of the locking nut (5c), and an inner o-ring groove (42a) formed inside the stepped portion (42) of the cylindrical sleeve (4c) for inserting an elastic part (2Oe) of spherical shape, so that a fastening force is adjusted between the cylindrical sleeve (4c) and the locking nut (5c) through the fastening bolt (9a).

[20] A rib-thread type sleeve as claimed in claim 16, further comprising an o-ring groove (57a) formed on an outer surface of the stepped portion (57) of the locking nut (5c), a spring mount groove (42d) formed at both ends of the cylindrical sleeve (4s) for inserting a clamp-spring (9n), and a clamp-spring (9n) inserted into the spring mount groove (42d), so that a fastening force is exerted to bond the cylindrical sleeve (4s) and the locking nut (5c) through the spring mount groove (42d).

[21] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a cylindrical sleeve (4e) having a rib-thread (41) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia) with a stepped portion (43) for bonding, which has a smaller diameter than that of the cylindrical sleeve (4e), and a pair of locking nuts (5e) formed with a stepped portion (58) having female threads (58a) for mating to the stepped portion (43) of the cylindrical sleeve (4e).

[22] A rib-thread type sleeve as claimed in claim 21, further comprising an o-ring groove (43 a) formed on an outer surface of the stepped portion (43) of the cylindrical sleeve (4e) for inserting an elastic o-ring (20c), an inner o-ring groove (58a) formed inside the stepped portion (58) of the locking nut (5e) for inserting the o-ring (20c), so that a resilient force is exerted on the locking nut (5e) to bond the assembly into one unified body, and a set of indicating marks (40, 59) disposed on the outer surfaces of the cylindrical sleeve (4e) and the locking nuts (5e).

[23] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a cylindrical sleeve (4b) having a rib-thread (41) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), an inner stepped coupling element (42) with an inner o-ring mounting groove (42a) for inserting an o-ring

(20c) disposed at both end portions, which has a larger inner diameter than that of the cylindrical sleeve (4b), an inner locking nut (7c) having an outer stepped coupling element (57) formed with a male thread (71), which has a smaller outer diameter than that of the locking nut (7c), an outer o-ring mounting groove (57a) for inserting the o-ring

(20c), and an outer locking nut (8a) formed with a female thread (81) on its inner surface for mating with the male thread (71) of the inner locking nut (7c).

[24] A method for coupling reinforcing bars by using a cylindrical type sleeve, the method comprising the steps of: inserting and loosely assembling a pair of locking nuts (53) into both ends of the cylindrical sleeve, inserting one end of a reinforcing bar (1) into one end of the loosely assembled sleeve along the longitudinal direction, so that one end portion of the reinforcing bar is located inside of the assembled sleeve, inserting an end of another reinforcing bar (Ia) into the other end of the loosely assembled sleeve along the opposite longitudinal direction, so that the other end portion of the reinforcing bar is located inside of the assembled sleeve, tightening the loosely assembled sleeve by rotating the nut portions in opposite directions from each other until a gap between the reinforcing bars (1, Ia) is completely eliminated to form a unified body.

[25] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: a cylindrical sleeve having a rib-thread (41) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), and an intermediate stopper (9b) inserted into the middle of the cylindrical sleeve along the longitudinal direction.

[26] A rib-thread type sleeve as claimed in claim 25, wherein said intermediate stopper (9b) has a rib-thread formed on the circumferential surface with the same rib (11) pattern as the reinforcing bars (1, Ia), and said intermediate stopper (9b) has a shape similar to a short set screw, two semi-spherical convex lateral surfaces (94), and a hex key recess (95) in one of the lateral surfaces (94).

[27] A rib-thread type sleeve for coupling reinforcing bars by tightening ribs to ribs, comprising: an inner sleeve (100) having a female rib-thread (101) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia), an outer sleeve (100a) having a female rib-thread (101) formed on its inner surface for mating to the ribs (11) of reinforcing bars (1, Ia) and a fine male thread (103) formed on its outer surface, and a coupling socket (200) formed with a collar (201) at its inner end for captivating the inner sleeve (100), and a female fine thread (203) at its inner mouth for engaging with the fine male thread (103) of the outer sleeve (100a). [28] A rib-thread type sleeve as claimed in claim 27, further comprising: an inner sleeve (100b) formed with a stepped inner restrictor (105) at its mouth, and an outer stepped restrictor (106) in the middle of the top portion, an outer sleeve (100c) formed with a stepped inner restrictor (105) at its mouth, a coupling socket (200a) forming a stepped inner restrictor (202) at a quarter of its length, a male gap adjuster (300) formed with a stepped outer restrictor (301) to contact the stepped inner restrictor (105), and a convex element (402) of trapezoidal cross-section at one lateral end, and contacting a tip of the reinforcing bars (1,

Ia) at the other lateral end, a female gap adjuster (400) formed with a stepped outer restrictor (401) to contact the stepped inner restrictor (105), and a concave element (302) of trapezoidal cross-section at one lateral end, and contacting a tip of the reinforcing bars (1, Ia) at the other lateral end.