Mechanical connection joint of steel bar and construction method

Abstract

The application provides a reinforced mechanical connection joint and a construction method, which comprises two ribbed steels, two connecting sleeves and connecting screws, the inner hole of the connecting sleeve is a stepped hole, the smaller diameter hole is provided with internal threads along the whole length, and the larger diameter hole is provided with a plurality of annular convex teeth, the outer diameter of the connecting sleeve corresponds to the side of the plurality of annular convex teeth and is provided with an extrusion section; the end of the ribbed steel is processed into a steel wire head which is matched with the internal threads of the connecting sleeve; the extrusion section of the connecting sleeve is extruded by an extrusion device, so that the plurality of annular convex tooth sections of the connecting sleeve are plastically deformed, the convex part of the plurality of annular convex tooth sections extrudes a groove on the cross rib of the ribbed steel, and the inner diameter of the plurality of annular convex tooth sections is shrunk and deformed to form a close fit with the cross rib and the base circle surface of the ribbed steel. The connection between the ribbed steel and the connecting sleeve in the joint adopts a combination process of tooth fit extrusion connection, thread fit connection and thread extrusion connection, so that the tensile strength of the joint is improved.

Description

Technical Field

[0001] This invention relates to a mechanical connection joint for reinforcing bars and a construction method thereof. Background Technology

[0002] Mechanical splicing technology for steel bars is widely used in modern building construction. However, for some structures with particularly high safety requirements, such as the nuclear island structure of nuclear power plants, the mechanical splices for steel bars must be able to withstand the impact of a large aircraft, meaning that the splice will fail on the parent material of the steel bar under instantaneous loading force.

[0003] In existing straight thread connection technologies, the rolled straight thread of the rebar weakens the rebar cross-section, especially the extended thread type joint, which has an additional thread outside the sleeve. Under instantaneous loading force, it usually breaks at the exposed thread of the rebar. Upsetting straight thread joints also cause damage to the surface of the rebar due to the clamping mold near the rebar connection end, and cannot ensure that the processed rebar meets the requirement of instantaneous loading failure at the location of the rebar parent material. Only the sleeve extrusion joint causes the least damage to the rebar parent material, but this method has a long on-site extrusion connection operation time. In addition, in areas with very dense rebar, the extrusion equipment is difficult to use within the space provided by the work station, and the connection operation cannot be completed.

[0004] Therefore, there has been no good solution for mechanical steel rebar connections that are fast to connect on-site, have good joint performance, reliable connection quality, and low overall cost, which are required for important projects. Summary of the Invention

[0005] The purpose of this invention is to provide a mechanical connection joint for reinforcing bars and a construction method therefor, thereby solving the aforementioned technical problems existing in the prior art.

[0006] The technical means adopted in this invention are as follows:

[0007] A mechanical connection joint for reinforcing bars, characterized in that it comprises two ribbed reinforcing bars, two connecting sleeves, and a connecting bolt, wherein:

[0008] The inner hole of the connecting sleeve is a stepped hole, in which the smaller diameter hole is provided with internal thread along its entire length, and the larger diameter hole is provided with multiple annular protrusions. The outer diameter of the connecting sleeve is provided with a pressing section on one side of the multiple annular protrusions. The minor diameter of the internal thread is smaller than the nominal diameter of the ribbed steel bar, and the minor diameter of the multiple annular protrusions is larger than the outer contour diameter of the ribbed steel bar.

[0009] The ends of the ribbed steel bars are machined with steel bar threads. The major diameter of the steel bar threads is smaller than the minor diameter of the multiple annular protrusions of the connecting sleeve. The steel bar threads are engaged with the internal threads of the connecting sleeve and are fully screwed into the internal threads. The internal threads of the connecting sleeve have a threaded section that connects to the connecting screw.

[0010] The extrusion section of the connecting sleeve is extruded by an extrusion device, causing multiple annular toothed sections of the connecting sleeve to undergo plastic deformation. The protruding parts of the multiple annular toothed sections press out grooves on the transverse and longitudinal ribs of the ribbed steel bar. At the same time, the inner cavity of the multiple annular toothed sections shrinks and deforms to form a tight fit with the transverse ribs and base circle surface of the ribbed steel bar, forming a partial toothed and extrusion fit connection.

[0011] The connecting screw has a first external thread and a second external thread at both ends. The first external thread and the second external thread are respectively engaged with the internal threads of the two connecting sleeves. The two ribbed steel bars are connected together through the connecting screw.

[0012] The aforementioned mechanical connection joint for reinforcing bars, wherein the extrusion equipment extrudes the extrusion section of the connecting sleeve, and also extrudes the adjacent area of ​​the internal thread of the connecting sleeve and multiple annular protrusions, and causes the internal thread portion to form an extrusion fit connection with the tail thread of the reinforcing bar thread.

[0013] The aforementioned mechanical connection joint for reinforcing bars includes a boss or groove between the first and second external threads of the connecting screw, the length of the second external thread being greater than the length of the first external thread, a locking nut being installed on the second external thread of the connecting screw, and the thread length of the internal thread of the connecting sleeve that mates with the second external thread being greater than the thread length of the internal thread of the connecting sleeve that mates with the first external thread.

[0014] The aforementioned mechanical connection joint for reinforcing bars includes two ribbed reinforcing bars with different diameters, two connecting sleeves with different inner diameters (each adapted to the diameter of the two ribbed reinforcing bars), and connecting screws with different diameters at both ends (each adapted to the diameter of the two ribbed reinforcing bars).

[0015] The aforementioned mechanical connection joint for reinforcing bars, wherein the length of the reinforcing bar thread is 0.6 to 1.15 times the nominal diameter of the reinforcing bar.

[0016] In the aforementioned mechanical connection joint for reinforcing bars, the length of the plurality of annular protruding teeth of the connecting sleeve is 0.5 to 1.5 times the nominal diameter of the ribbed reinforcing bar.

[0017] The aforementioned mechanical connection joint for reinforcing bars, wherein the plurality of annular protrusions are replaced by internal threads of another triangular tooth type.

[0018] A construction method for a rebar mechanical connection joint, using the aforementioned rebar mechanical connection joint, is characterized by comprising the following steps:

[0019] The first step is to process the ends of the two ribbed steel bars into steel bar threads;

[0020] The second step is to insert one end of the two connecting sleeves with multiple annular protrusions into the end of the ribbed steel bar, and rotate the connecting sleeve until the steel bar threads of the ribbed steel bar are all inserted into the internal thread of the connecting sleeve. The internal thread of the connecting sleeve has a threaded section that connects to the connecting screw.

[0021] The third step is to operate the extrusion equipment to extrude the extrusion section of the connecting sleeve, so that the end of the connecting sleeve with multiple annular protrusions undergoes plastic deformation. The protruding part of the multiple annular protrusions presses out grooves on the transverse and longitudinal ribs of the ribbed steel bar. At the same time, the inner cavity of the multiple annular protrusions shrinks and deforms, forming a tight fit with the transverse ribs and base circle surface of the ribbed steel bar, forming a partial toothed and extrusion fit connection.

[0022] The fourth step is to screw the first external thread of one end of the connecting screw into a connecting sleeve, so that the end face of the first external thread abuts against the end face of the ribbed steel bar inside the connecting sleeve.

[0023] Fifth step, move the two connecting sleeves and their connected ribbed steel bars to a relative position. After the two ribbed steel bars face each other and are coaxially aligned, rotate the ribbed steel bars relative to each other to screw the second external thread of the connecting screw into the internal thread of the other connecting sleeve. The two ribbed steel bars move towards each other as they rotate relative to each other until the end face of the second external thread of the connecting screw abuts against the end face of its corresponding ribbed steel bar.

[0024] The sixth step is to use a wrench to tighten the two steel bars by rotating them relative to each other until the tightening torque meets the specified requirements.

[0025] A construction method for a rebar mechanical connection joint, using the aforementioned rebar mechanical connection joint, is characterized by comprising the following steps:

[0026] The first step is to process the ends of the two ribbed steel bars into steel bar threads;

[0027] The second step involves setting up two connecting sleeves, one with a shorter internal thread and the other with a longer internal thread. The two connecting sleeves are fitted into the end of the ribbed steel bar with multiple annular protrusions. The connecting sleeves are rotated until the steel bar threads of the ribbed steel bar are fully inserted into the internal thread of the connecting sleeve. The internal thread of each connecting sleeve has a threaded section that connects to the connecting screw.

[0028] The third step is to operate the extrusion equipment to extrude the extrusion section of the connecting sleeve, so that the end of the connecting sleeve with multiple annular protrusions undergoes plastic deformation. The protruding part of the multiple annular protrusions presses out grooves on the transverse and longitudinal ribs of the ribbed steel bar. At the same time, the inner cavity of the multiple annular protrusions shrinks and deforms, forming a tight fit with the transverse ribs and base circle surface of the ribbed steel bar, forming a partial toothed and extrusion fit connection.

[0029] Fourth step, screw the locking nut onto the second external thread of the connecting screw, and rotate the locking nut to the position where it abuts against the stepped surface of the boss or groove. Then screw the second external thread of the connecting screw into the internal thread of the other connecting sleeve with a longer internal thread until the locking nut abuts against the end face of the other connecting sleeve.

[0030] Fifth step: Align the two ribbed steel bars coaxially towards each other, and adjust the longitudinal relative position of the two ribbed steel bars until the axial gap between the end face of the first external thread of the connecting screw and the outer end face of the connecting sleeve with the shorter internal thread is within the specified connection size range of the connecting screw. Then the relative position of the two ribbed steel bars will be fixed.

[0031] Step 6: Rotate the connecting screw in the opposite direction so that the second external thread of the connecting screw is unscrewed from the other connecting sleeve with the longer internal thread, and the first external thread is screwed into the internal thread of the connecting sleeve with the shorter internal thread, until the end face of the first external thread of the connecting screw abuts against the end face of the ribbed steel bar inside the connecting sleeve.

[0032] Step 7: Use a wrench to rotate the boss or groove of the connecting screw until the tightening torque reaches the specified value;

[0033] Step 8: Use a wrench to turn the lock nut so that it is close to the end face of the other connecting sleeve, tighten it and make the tightening torque reach the specified value.

[0034] The advantages of this invention are:

[0035] 1. The connection between the ribbed steel bar and the connecting sleeve in the joint of the present invention adopts a combination of three connection processes: toothed fit extrusion connection, threaded fit connection, and threaded extrusion connection, which improves the tensile strength of the joint.

[0036] This invention utilizes the advantage of threaded connections in efficiently transmitting loads to bear the main load borne by ribbed reinforcing bars. At the tail end of the threaded connection, a compression connection is used to deform and cold-work the end of the reinforcing bar wire, improving the metal strength of the wire end, the tightness of the threaded fit with the connecting sleeve, and the cross-sectional load-bearing capacity, further enhancing the efficiency of the threaded connection. The final compression section is connected to the transverse ribs of the reinforcing bar body through compression. The raised portions of the multiple annular protrusions (or triangular internal threads) of the connecting sleeve press grooves into the transverse and longitudinal ribs of the ribbed reinforcing bar, still providing cold-work strengthening. The inner cavity of each annular protruding tooth segment contracts and deforms to form a tight fit with the transverse ribs and base circle surface of the ribbed steel bar. This connection segment does not damage the base circle surface of the steel bar and shares the load borne by the ribbed steel bar with the threaded part of the steel bar thread. Compared with the traditional straight thread steel bar joint, the maximum stress cross section of the ribbed steel bar on the joint is transferred from the tail of the steel bar thread to the joint segment where multiple annular protruding teeth are squeezed by the steel bar. This solves the problem that the straight thread connection of steel bars is prone to damage at the weakened tail of the steel bar thread, ensuring that the joint connection strength exceeds that of the steel bar parent material and meets the highest strength performance requirements of the steel bar mechanical joint.

[0037] 2. The connector adopts field threaded connection and factory extrusion connection processes, which improves the production efficiency of station connection and reduces connection processing costs.

[0038] The connector of this invention employs a composite connection process of threaded connection and extrusion connection. Firstly, the length of the rebar thread connected to the connecting sleeve can be shortened by approximately 40% to 50% compared to that of a rebar thread connected by a conventional straight thread, while the rebar thread processing accuracy can be reduced to grade 7, significantly improving the production efficiency of rebar thread processing in the factory. Secondly, the extrusion connection between the connecting sleeve and the rebar thread is completed in the factory. The extrusion area and extrusion section length of the connecting sleeve are much smaller than those of traditional sleeve extrusion connection connectors. The extrusion equipment has low output force and fast operation, enabling automatic extrusion processing. Furthermore, the extrusion fit of the thread near the end of the rebar thread eliminates the need for a specified torque tightening operation between the connecting sleeve and the rebar thread, thus eliminating the torque detection device in the automatic production line for tightening sleeves. This reduces the cost of automated equipment for thread processing and connector installation in the prefabrication plant, and lowers the cost of prefabrication connection processing operations. Finally, the connecting screw is pre-installed in the connecting sleeve of a rebar, and the connection at the work station is simply the connection of the external thread at the other end of the connecting screw to the connecting sleeve of the other rebar. The number of rotations is equal to or less than that of traditional straight thread connections, making the connection process on the construction site simple and easy, significantly improving the speed of rebar connection and the progress of project construction, saving on-site labor and equipment costs, and improving overall economic efficiency indicators.

[0039] 3. The connection quality and deformation performance stability of this joint are far superior to those of traditional mechanical steel bar connections.

[0040] Prefabricate the steel rebar ends in the factory or on the ground. The prefabricated steel rebar is then threaded and extruded into the connecting sleeve. The extrusion fit of the threads near the tail of the steel rebar ends eliminates the thread fit gap between the internal threads of the connecting sleeve and the rebar ends. Even if, as described in claim 9, the second external thread of the connecting screw is unscrewed out of the connecting sleeve in the opposite direction, and the connecting screw cannot press against the end face of the ribbed steel rebar ends inside the connecting sleeve, the extrusion fit between the extruded section of the connecting sleeve and the steel rebar ends and the transverse and longitudinal ribs on the outer surface of the steel rebar can reduce the axial gap of the connection fit between the ribbed steel rebar and the connecting sleeve to the level required for the joint deformation performance. The on-site connection uses a straight threaded connection between the connecting screw and the connecting sleeve. Since both the connecting screw and the connecting sleeve are factory-manufactured products, their thread processing accuracy and fit accuracy are far superior to the traditional on-site processing of rebar threads and straight threaded sleeves. With this joint, as long as the operator applies a small amount of tightening torque, the screw will press against the rebar inside the connecting sleeve, or the connecting screw can be tightened onto the connecting sleeve with a lock nut. The axial clearance of this threaded connection can be significantly reduced. Therefore, although the on-site connection also uses a traditional threaded connection to tighten the joint, the deformation performance of the joint is far superior to that of ordinary rebar straight threaded thread and straight threaded sleeve connections. The connection strength quality and deformation performance stability of the joint are much better than existing types of rebar straight thread joints and sleeve extrusion straight thread joints.

[0041] 4. This joint has excellent impact resistance, and its cost and performance are superior to existing impact-resistant steel bar joints.

[0042] Since the outermost part of the connection between the connecting sleeves at both ends of the joint and the reinforcing bar is a compression connection, it only strengthens and slightly deforms the outer surface of the connected reinforcing bar, without causing any damage to the reinforcing bar. Therefore, when the reinforcing bar is subjected to the impact force of instantaneous large deformation, it will not be damaged at the joint connection site due to the damage to the processing of the reinforcing bar caused by the joint connection. Compared to existing single-extrusion connection impact-resistant joints, the threaded connection between the connecting sleeve and the reinforcing bar of this joint bears most of the load, effectively shortening the joint length by at least 5 to 6 times the diameter of the reinforcing bar. This significantly reduces material consumption and cost of the connectors. Compared to impact-resistant joints that are cold-extruded and reinforced with ribs and then threaded, this joint solves the problem that the quality stability of cold-pressed or necked-up reinforcing bars is greatly affected by the shape and mechanical properties of the reinforcing bars. The processing quality of the reinforcing bar threads in this joint is not affected by the shape of the reinforcing bar. The threaded connection end is only part of the load-bearing structure of this joint. The deformation of the extrusion connection section is controlled by pressure and can achieve a tight fit without being affected by deviations in the diameter of the reinforcing bar. The combination of threaded and extrusion connections makes the connection quality almost 100% reliable. Moreover, since the connection performance of this joint is almost unaffected by the mechanical properties of the reinforcing bar, even reinforcing bars with a yield strength of 700MPa can have good resistance to instantaneous large deformation impacts through the application of a matching connecting sleeve. This is unmatched by ordinary straight thread joints and reinforcing bar reinforced straight thread joints. Attached Figure Description

[0043] Figure 1 This is a structural schematic diagram of the first embodiment of the mechanical connection joint for reinforcing bars provided by the present invention.

[0044] Figure 2 This is a structural schematic diagram of the second embodiment of the mechanical connection joint for reinforcing bars provided by the present invention.

[0045] Figure 3 This is a structural schematic diagram of the third embodiment of the mechanical connection joint for reinforcing bars provided by the present invention.

[0046] Figure 4 This is a structural schematic diagram of the fourth embodiment of the mechanical connection joint for reinforcing bars provided by the present invention. Detailed Implementation

[0047] like Figure 1 The image shows a first embodiment of the mechanical connection joint for reinforcing bars provided by the present invention, comprising two ribbed reinforcing bars 1, two connecting sleeves 2, and a connecting bolt 3, wherein:

[0048] The inner hole of the connecting sleeve 2 is a stepped hole, in which the smaller diameter hole is provided with an internal thread 21 along its entire length, and the larger diameter hole is provided with multiple annular protrusions 22 (or another triangular tooth type internal thread). The outer diameter of the connecting sleeve 2 is provided with a pressing section 23 on one side corresponding to the multiple annular protrusions 22 (or another triangular tooth type internal thread). The minor diameter of the internal thread 21 is smaller than the nominal diameter of the ribbed steel bar 1, and the minor diameter of the multiple annular protrusions 22 (or another triangular tooth type internal thread) is larger than the outer contour diameter of the ribbed steel bar 1.

[0049] The end of the ribbed steel bar 1 is machined with a steel bar thread 11. The major diameter of the thread of the steel bar thread 11 is smaller than the minor diameter of the multiple annular protrusions 22 of the connecting sleeve 2. The steel bar thread 11 is engaged with the internal thread 21 of the connecting sleeve 2 and is fully screwed into the internal thread 21. The internal thread 21 of the connecting sleeve 2 is provided with a threaded section for connection with the connecting screw 3.

[0050] The extrusion section 23 of the connecting sleeve 2 is extruded by an extrusion device, causing plastic deformation of the multiple annular protrusions 22 (or another triangular internal thread) of the connecting sleeve 2. The protruding parts of the multiple annular protrusions 22 (or another triangular internal thread) press out grooves on the transverse and longitudinal ribs of the ribbed steel bar 1. At the same time, the inner cavity of the multiple annular protrusions 22 (or another triangular internal thread) shrinks and deforms to form a tight fit with the transverse ribs and base circle surface of the ribbed steel bar 1, forming a partial toothed and extrusion fit connection.

[0051] The extrusion device extrudes the extrusion section 23 of the connecting sleeve 2, and may also extrude the adjacent area of ​​the internal thread 21 of the connecting sleeve 2 and multiple annular protrusions 22 (or another triangular tooth type internal thread), and make a partial thread of the internal thread 21 form an extrusion fit connection with the tail thread of the steel wire head 11.

[0052] The connecting screw 3 has a first external thread 31 and a second external thread 32 at both ends. The first external thread 31 and the second external thread 32 respectively cooperate with the internal threads 21 of the two connecting sleeves 2. The two ribbed steel bars 1 are connected together in series through the connecting screw 3 (and can be tightened in sequence).

[0053] The construction method for a mechanical connection joint of reinforcing bars provided by the present invention includes the following steps:

[0054] The first step is to process the ends of the two ribbed steel bars 1 to produce steel bar threads 11;

[0055] The second step is to insert one end of the two connecting sleeves 2 with multiple annular protrusions 22 (or another triangular tooth type of internal thread) into the end of the ribbed steel bar 1, and rotate the connecting sleeve 2 until the steel bar thread 11 of the ribbed steel bar 1 is completely inserted into the internal thread 21 of the connecting sleeve 2. The internal thread 21 of the connecting sleeve 2 has a threaded section that is connected to the connecting screw 3.

[0056] The third step involves operating the extrusion equipment to extrude the extrusion section 23 of the connecting sleeve 2, causing one end of the connecting sleeve 2 with multiple annular protrusions 22 (or another triangular internal thread) to undergo plastic deformation. The protruding parts of the multiple annular protrusions 22 (or another triangular internal thread) press grooves into the transverse and longitudinal ribs of the ribbed steel bar 1. At the same time, the inner cavity of the end of the multiple annular protrusions 22 (or another triangular internal thread) shrinks and deforms, forming a tight fit with the transverse ribs and base circle surface of the ribbed steel bar 1, forming a partial toothed and extrusion fit connection.

[0057] In a preferred embodiment, the extrusion device extrudes the extrusion section 23 of the connecting sleeve 2, and also extrudes the area adjacent to the internal thread 21 of the connecting sleeve 2 and a plurality of annular protrusions 22 (or another triangular tooth type internal thread), and makes the thread of the internal thread 21 part form an extrusion fit connection with the tail thread of the steel wire 11.

[0058] The fourth step is to screw the first external thread 31 of one end of the connecting screw 3 into a connecting sleeve 2, so that the end face of the first external thread 31 abuts against the end face of the ribbed steel bar 1 inside the connecting sleeve 2.

[0059] Fifth step, move the two connecting sleeves 2 and the ribbed steel bars 1 connected to them to a relative state. After the two ribbed steel bars 1 face each other and are coaxially aligned, rotate the two ribbed steel bars 1 relative to each other to screw the second external thread 32 of the connecting screw 3 into the internal thread 21 of the other connecting sleeve 2. The two ribbed steel bars 1 move towards each other as they rotate relative to each other until the end face of the second external thread 32 of the connecting screw 3 abuts against the end face of its corresponding ribbed steel bar 1.

[0060] Step 6: Use a wrench to tighten the two reinforcing bars by rotating them relative to each other. Once the tightening torque reaches the specified requirement, the connection of the two ribbed reinforcing bars 1 that can move axially and rotate relative to each other is completed.

[0061] Please refer to this again. Figure 2 , Figure 3These are the second and third embodiments provided by the present invention. Compared with the first embodiment, the difference is that a boss 33 or a groove 34 is provided between the first external thread 31 and the second external thread 32 of the connecting screw 3 (the boss 33 and the groove 34 include a pair of symmetrical planes parallel to the axis of the connecting screw 3, which are convenient to be turned with a wrench). The length of the second external thread 32 is greater than the length of the first external thread 31. A locking nut 4 is installed on the second external thread 32 of the connecting screw 3. The thread length of the internal thread 21 of the connecting sleeve 2 that is connected to the second external thread 32 is greater than the thread length of the internal thread 21 of the connecting sleeve 2 that is connected to the first external thread 31.

[0062] In the first, second, and third embodiments, the length of the reinforcing bar wire 11 of the ribbed steel bar 1 is 0.6 to 1.15 times the nominal diameter of the ribbed steel bar 1.

[0063] In the first, second, and third embodiments, the length of the plurality of annular protrusions 22 (or another internal thread) of the connecting sleeve 2 is 0.5 to 1.5 times the nominal diameter of the ribbed steel bar 1.

[0064] The construction methods for the mechanical connection joints of the reinforcing bars in the second and third embodiments include the following steps:

[0065] The first step is to process the ends of the two ribbed steel bars 1 to produce steel bar threads 11;

[0066] The second step is to insert one end of the two connecting sleeves 2 (including one connecting sleeve 2 with a shorter internal thread 21 and another connecting sleeve 2 with a longer internal thread 21) with multiple annular protrusions 22 (or another triangular tooth type internal thread) into the end of the ribbed steel bar 1, and rotate the connecting sleeve 2 until the steel bar thread 11 of the ribbed steel bar 1 is completely inserted into the internal thread 21 of the connecting sleeve 2. The internal thread 21 of the connecting sleeve 2 has a threaded section that connects to the connecting screw 3.

[0067] The third step involves operating the extrusion equipment to extrude the extrusion section 23 of the connecting sleeve 2, causing plastic deformation at one end of the connecting sleeve 2 with multiple annular protrusions 22 (or another triangular internal thread). The protruding parts of the multiple annular protrusions 22 (or another triangular internal thread) press grooves into the transverse and longitudinal ribs of the ribbed steel bar 1. At the same time, the inner cavity of the multiple annular protrusions 22 (or another triangular internal thread) section shrinks and deforms, forming a tight fit with the transverse ribs and base circle surface of the ribbed steel bar 1, forming a partial toothed and extrusion fit connection.

[0068] In a preferred embodiment, the extrusion device extrudes the extrusion section 23 of the connecting sleeve 2, and also extrudes the area adjacent to the internal thread 21 of the connecting sleeve 2 and a plurality of annular protrusions 22 (or another triangular tooth type internal thread), and makes the thread of the internal thread 21 part form an extrusion fit connection with the tail thread of the steel wire 11.

[0069] Fourth step, screw the locking nut 4 to the second external thread 32 of the connecting screw 3, and rotate the locking nut 4 to the position of abutting against the stepped surface of the boss 33 (or groove 34), and then screw the second external thread 32 of the connecting screw 3 into the internal thread 21 of the other connecting sleeve 2 which has a longer internal thread 21, until the locking nut 4 abuts against the end face of the other connecting sleeve 2;

[0070] Fifth step, align the two ribbed steel bars 1 facing each other on the same axis, and adjust the longitudinal relative position of the two ribbed steel bars 1 until the axial gap between the end face of the first external thread 31 of the connecting screw 3 and the outer end face of the connecting sleeve 2 with the shorter internal thread 21 is within the specified connecting size range of the connecting screw 3, then the relative position of the two ribbed steel bars 1 is fixed.

[0071] Step 6: Rotate the connecting screw 3 in the opposite direction so that the second external thread 32 of the connecting screw 3 is screwed out from the other connecting sleeve 2 which has a longer internal thread 21, and the first external thread 31 is screwed into the internal thread 21 of the connecting sleeve 2 which has a shorter internal thread 21, until the end face of the first external thread 31 of the connecting screw 3 abuts against the end face of the ribbed steel bar 1 inside the connecting sleeve 2.

[0072] Step 7: Use a wrench to rotate the boss 33 (or groove 34) of the connecting screw 3 until the tightening torque reaches the specified value;

[0073] Step 8: Use a wrench to turn the locking nut 4 so that the locking nut 4 is close to the end face of the other connecting sleeve 2, tighten it and make the tightening torque reach the specified value. The connection of the two ribbed steel bars 1 with relatively fixed axial positions and unable to rotate relative to each other is completed.

[0074] For example Figure 4 The figure shows the fourth embodiment provided by the present invention. Compared with the third embodiment, the difference is that it is used for connecting steel bars of different diameters, that is, the diameters of the two ribbed steel bars 1 are different. Therefore, the inner diameters of the two connecting sleeves 2 are also different, respectively adapted to the diameters of the two ribbed steel bars 1. Moreover, the diameters of the two ends of the connecting screw 3 are also different, respectively adapted to the diameters of the two ribbed steel bars 1.

[0075] The above-described connection structure for steel bars of different diameters can also be applied to the first embodiment and the second embodiment.

[0076] Furthermore, the steel bar connection construction method in the fourth embodiment is the same as that in the third embodiment, and will not be described in detail here.

[0077] The advantages of this invention are:

[0078] 1. High joint connection strength:

[0079] Traditional rebar rolling straight threading process damages the rebar's shape and inevitably reduces its cross-sectional area, affecting the joint strength. Rebar sleeve extrusion connection causes less damage to the rebar, but requires a larger fitting size, and on-site extrusion requires multiple passes, resulting in low construction efficiency. This joint uses a composite connection structure of threaded and extruded connections. The threaded connection between the sleeve and the rebar bears the main load of the rebar, significantly shortening the sleeve's length. The extruded connection of the sleeve bears part of the rebar's load. Because extrusion causes minimal damage to the rebar's cross-section, under tensile and compressive loads, the extruded section bears the load first and deforms with the rebar when the stress is high. The load jointly borne by the extruded and threaded sections can exceed the ultimate load that the rebar can withstand. Therefore, this joint has higher connection strength than ordinary straight thread joints, and is particularly suitable for connecting high-strength rebar that is sensitive to surface defects.

[0080] 2. High efficiency in on-site connection:

[0081] The connecting sleeve of this joint is prefabricated. Before the steel bars arrive at the on-site connection station, the connection between the connecting sleeve and the steel bars is completed at the ground steel bar processing plant. At the on-site station, only the threaded connection between the connecting bolt and the connecting sleeve remains. Since the processing of the connecting parts is guaranteed by the manufacturing precision in the factory, the on-site connection speed can exceed that of traditional steel bar straight thread connection. Therefore, the steel bar connection on the construction site has a high connection efficiency.

[0082] 3. High-quality on-site connection:

[0083] As mentioned above, both the connecting bolt and the connecting sleeve thread are factory-manufactured. Factory equipment boasts high processing precision, resulting in products with higher precision than those processed by on-site rebar thread processing equipment. Therefore, on-site connections offer high precision, convenient installation, and reliable connection quality. In prefabricated joint connections, the prefabrication process at the prefabrication plant or on-site rebar processing yard can ensure the connection quality between the connecting sleeve and the rebar using equipment precision and automated control. The stability of the joint connection quality is higher than that of traditional rebar straight thread connection joints, which are greatly affected by human factors and the precision of processing equipment. Achieving high-quality joint construction is no longer just a slogan or a pursuit, but an easily achievable reality.

Claims

1. A mechanical connection joint for reinforcing bars, characterized in that, It includes two ribbed steel bars (1), two connecting sleeves (2), and a connecting bolt (3), wherein: The inner hole of the connecting sleeve (2) is a stepped hole, in which the smaller diameter hole is provided with an internal thread (21) along its entire length, and the larger diameter hole is provided with multiple annular protrusions (22). The outer diameter of the connecting sleeve (2) is provided with a pressing section (23) on one side of the multiple annular protrusions (22). The minor diameter of the internal thread (21) is smaller than the nominal diameter of the ribbed steel bar (1), and the minor diameter of the multiple annular protrusions (22) is larger than the outer contour diameter of the ribbed steel bar (1). The end of the ribbed steel bar (1) is machined with a steel bar thread (11). The major diameter of the thread of the steel bar thread (11) is smaller than the minor diameter of the multiple annular protrusions (22) of the connecting sleeve (2). The steel bar thread (11) is engaged with the internal thread (21) of the connecting sleeve (2) and is fully screwed into the internal thread (21). The internal thread (21) of the connecting sleeve (2) is provided with a threaded section for connection with the connecting screw (3). The extrusion section (23) of the connecting sleeve (2) is extruded by the extrusion equipment, causing the multiple annular protrusions (22) of the connecting sleeve (2) to undergo plastic deformation. The protruding part of the multiple annular protrusions (22) presses out grooves on the transverse and longitudinal ribs of the ribbed steel bar (1). At the same time, the inner cavity of the multiple annular protrusions (22) shrinks and deforms to form a tight fit with the transverse ribs and base circle surface of the ribbed steel bar (1), forming a partial toothed and extrusion fit connection. The connecting screw (3) has a first external thread (31) and a second external thread (32) at both ends. The first external thread (31) and the second external thread (32) are respectively engaged with the internal threads (21) of the two connecting sleeves (2). The two ribbed steel bars (1) are connected together through the connecting screw (3).

2. The mechanical connection joint for reinforcing bars according to claim 1, characterized in that, The extrusion device extrudes the extrusion section (23) of the connecting sleeve (2), and also extrudes the adjacent area of ​​the internal thread (21) of the connecting sleeve (2) and multiple annular protrusions (22), and makes the thread of the internal thread (21) form an extrusion fit connection with the tail thread of the steel wire (11).

3. The mechanical connection joint for reinforcing bars according to claim 1, characterized in that, A boss (33) or a groove (34) is provided between the first external thread (31) and the second external thread (32) of the connecting screw (3). The length of the second external thread (32) is greater than the length of the first external thread (31). A locking nut (4) is installed on the second external thread (32) of the connecting screw (3). The thread length of the internal thread (21) of the connecting sleeve (2) that mates with the second external thread (32) is greater than the thread length of the internal thread (21) of the connecting sleeve (2) that mates with the first external thread (31).

4. The mechanical connection joint for reinforcing bars according to claim 1, characterized in that, The two ribbed steel bars (1) have different diameters, and the inner diameters of the two connecting sleeves (2) are also different, each corresponding to the diameter of the two ribbed steel bars (1). Furthermore, the diameters at both ends of the connecting screw (3) are also different, each corresponding to the diameter of the two ribbed steel bars (1).

5. The mechanical connection joint for reinforcing bars according to any one of claims 1-4, characterized in that, The length of the steel wire (11) of the ribbed steel bar (1) is 0.6 to 1.15 times the nominal diameter of the ribbed steel bar (1).

6. The mechanical connection joint for reinforcing bars according to any one of claims 1-4, characterized in that, The length of the plurality of annular protrusions (22) of the connecting sleeve (2) is 0.5 to 1.5 times the nominal diameter of the ribbed steel bar (1).

7. The mechanical connection joint for reinforcing bars according to any one of claims 1-4, characterized in that, The plurality of annular protrusions (22) are replaced with internal threads of another triangular tooth type.

8. A construction method for a mechanical connection joint for reinforcing bars, employing the mechanical connection joint for reinforcing bars as described in claim 1, characterized in that, The steps involved are as follows: The first step is to process the ends of the two ribbed steel bars (1) into steel bar threads (11); The second step is to insert one end of the two connecting sleeves (2) with multiple annular protrusions (22) into the end of the ribbed steel bar (1), and rotate the connecting sleeve (2) until the steel bar thread (11) of the ribbed steel bar (1) is completely inserted into the internal thread (21) of the connecting sleeve (2). The internal thread (21) of the connecting sleeve (2) is provided with a threaded section that connects to the connecting screw (3). The third step is to operate the extrusion equipment to extrude the extrusion section (23) of the connecting sleeve (2), so that the end of the connecting sleeve (2) with multiple annular protrusions (22) undergoes plastic deformation. The protruding part of the multiple annular protrusions (22) presses out grooves on the transverse and longitudinal ribs of the ribbed steel bar (1). At the same time, the inner cavity of the multiple annular protrusions (22) section shrinks and deforms, and forms a tight fit with the transverse ribs and base circle surface of the ribbed steel bar (1), forming a partial toothed and extrusion fit connection. Fourth step, screw the first external thread (31) of one end of the connecting screw (3) into a connecting sleeve (2) so that the end face of the first external thread (31) abuts against the end face of the ribbed steel bar (1) inside the connecting sleeve (2); Fifth step, move the two connecting sleeves (2) and their connected ribbed steel bars (1) to a relative state. After the two ribbed steel bars (1) are facing each other and coaxially aligned, rotate the two ribbed steel bars (1) relative to each other to screw the second external thread (32) of the connecting screw (3) into the internal thread (21) of the other connecting sleeve (2). The two ribbed steel bars (1) move towards each other as they rotate relative to each other until the end face of the second external thread (32) of the connecting screw (3) abuts against the end face of its corresponding ribbed steel bar (1). The sixth step is to use a wrench to tighten the two steel bars by rotating them relative to each other until the tightening torque meets the specified requirements.

9. A construction method for a mechanical connection joint for reinforcing bars, employing the mechanical connection joint for reinforcing bars as described in claim 3, characterized in that, The steps involved are as follows: The first step is to process the ends of the two ribbed steel bars (1) into steel bar threads (11); The second step involves two connecting sleeves (2), one of which has a shorter internal thread (21) and the other has a longer internal thread (21). The two connecting sleeves (2) have multiple annular protrusions (22) at one end, which are inserted into the end of the ribbed steel bar (1). The connecting sleeves (2) are rotated until the steel bar thread (11) of the ribbed steel bar (1) is completely inserted into the internal thread (21) of the connecting sleeve (2). The internal thread (21) of the connecting sleeve (2) has a threaded section that connects to the connecting screw (3). The third step is to operate the extrusion equipment to extrude the extrusion section (23) of the connecting sleeve (2), so that the end of the connecting sleeve (2) with multiple annular protrusions (22) undergoes plastic deformation. The protruding part of the multiple annular protrusions (22) presses out grooves on the transverse and longitudinal ribs of the ribbed steel bar (1). At the same time, the inner cavity of the multiple annular protrusions (22) section shrinks and deforms, and forms a tight fit with the transverse ribs and base circle surface of the ribbed steel bar (1), forming a partial toothed and extrusion fit connection. Fourth step, screw the locking nut (4) onto the second external thread (32) of the connecting screw (3), and rotate the locking nut (4) to abut against the stepped surface of the boss (33) or groove (34), and then screw the second external thread (32) of the connecting screw (3) into the internal thread (21) of the other connecting sleeve (2) with a longer internal thread (21) until the locking nut (4) abuts against the end face of the other connecting sleeve (2); Fifth step, align the two ribbed steel bars (1) facing each other on the same axis, and adjust the longitudinal relative position of the two ribbed steel bars (1) until the axial gap between the end face of the first external thread (31) of the connecting screw (3) and the outer end face of the connecting sleeve (2) with the shorter internal thread (21) is within the range of the connection size specified by the connecting screw (3), then the relative position of the two ribbed steel bars (1) will be fixed. Step 6: Rotate the connecting screw (3) in the opposite direction so that the second external thread (32) of the connecting screw (3) is screwed out from the other connecting sleeve (2) which has a longer internal thread (21), and the first external thread (31) is screwed into the internal thread (21) of the connecting sleeve (2) which has a shorter internal thread (21) until the end face of the first external thread (31) of the connecting screw (3) abuts against the end face of the ribbed steel bar (1) inside the connecting sleeve (2); Step 7: Use a wrench to rotate the boss (33) or groove (34) of the connecting screw (3) until the tightening torque reaches the specified value; Step 8: Use a wrench to turn the locking nut (4) so ​​that the locking nut (4) is close to the end face of the other connecting sleeve (2), tighten it and make the tightening torque reach the specified value.

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