TECHNICAL FIELD
The invention relates to a high tensile and compressive strengths mechanical reinforcing bars coupler. The coupler does not affect the effective cross-sectional area of the reinforcing bars as in case of threading or concentrate stresses at certain points as in case of notching. The coupler as presented could allow for connecting reinforcing bars ends with different diameters.
BACKGROUND ART
- 1—Lab Splice: It is the traditional technique used for decades and still used till now. The splice is made by lapping one of the reinforcing bars over the other with a suitable length sufficient to transmit the tension or the compression forces from the curtailed bar to the starting one. The length and specifications are determined according to the reinforcing bars ending position and its diameter.
- 2—Welding Splice: This method is used in reinforcing steel bars with diameters larger than 16 mm according to the steel grade weld-ability on condition of axial alignment of the welded bars and welding is done using electric arc. The welding length and thickness are determined according to the ultimate tension capacity of the welded bars (1 and 2). The welded connection (3) is made either by splicing the bars then welding, as shown in FIG. (1) or making the connection by welding the bar ends together then welding two additional bars (4) on the connection sides, as shown in FIG. (2).
- 3—Mechanical Splices:
- 3-1—This splice is made in deformed reinforcing bars with diameter larger than 16 mm. In this case, a sleeve pipe (5) having adequate thickness with inner diameter equal to the reinforcing bars outer diameter is cold swaged on the two reinforcing bars ends (1 and 2), allowing for internally forming the inner surface of the sleeve pipe according to the reinforcing steel bar deformations, as shown in FIG. (3).
- 3-2—Another mechanical splice is formed using internally threaded sleeves (6) along with externally threading both the connected reinforcing steel bar ends (1 and 2) applying different threading techniques. In one of these methods, heating and/or compressing the reinforcing bars ends to increase their diameter then threading the reinforcing bars ends. The splice is made by assembling the steel reinforcing bars with the internally threaded sleeve (6), as shown in FIG. (4).
- 3-3—Another technique for mechanical splicing depends on making the connection from four parts and auxiliary assembling machine. The jaw assembly includes interior teeth (11) designed to bite into the projecting deformations (12) on the outside of the bar ends which form the overall diameter of the bar but not the core or nominal diameter of the bar. The jaw assembly is constricted from both axial ends by driving tapered locking collars (22) on each end of the jaw assembly with a tooth while concurrently causing the jaw assembly to constrict and bite into the bar ends. When the tool is removed, the collars remain in place locking the jaw assembly closed, as shown in FIG. (5).
- 3-4—FIG. 6 shows the bar look coupler. This coupling device consists of shaped, steel sleeve with two converging sides. A series of cone-pointed screws or shear bolts (8) are assembled along the sleeve length (9). Reinforcing bars (1) and (2) are inserted from each end to a center stop. When screws or bolts are tightened, they indent into the surface of the bars. The heads of the screws will shear off at a maximum tightening torque. This coupling device may be ordered in black, epoxy-coated, or galvanized, depending on the specified bar type requirement.
SHORTCOMINGS AND DRAWBACKS OF THE BACKGROUND ART
The background art has the following shortcomings and problems:
- 1—The lab splice technique, which is the most widely used one, the two ends of the concrete reinforcing steel bars are placed parallel in lapping position with the required lap length. Both bars are tied together with thin steel wire, as previously explained, which may lead to the following problems:
- a. Wasting large amount of steel reinforcement, which is about 1 to 1.5 m for each bar splice.
- b. In concrete sections with large reinforcing steel percentage, the number of reinforcing steel bars is doubled leading to the possibility of blocking the whole concrete section and therefore honeycombing of the concrete section in a critical section of the structural member.
- 2—In coupler connections, which are performed by compressing the coupler with the reinforcing steel bars inside, the connection is mostly made before placing the reinforcing bars in the formwork resulting in very long steel bar with difficulty in handling. On the other hand, performing the coupler bar connection inside the formwork is rather difficult due to the limited accessibility and the difficulty in placing the used machinery inside the formwork.
- 3—In case of threading the inner surface of the coupler and the outer surface of the reinforcing steel bars, threading the bars is performed first outside the formwork because revolving the coupler will result in revolving the connected steel bar along its whole length. This process could not be performed in steel bars on their position inside the formwork due to the limited area and presence of other steel bars.
- 4—The connection formed of four parts, as previously mentioned, depend on biting the threads in the two jaws with the male deformations in the reinforcing steel bars needing high compression energy and a special machine, which could not also assembled inside the formwork. In addition, large coupler length is needed to assure generating sufficient resistance between the threads and the reinforcing steel bar male deformations.
- 5—In the method depending on placing the two steel bars to be connected inside part of a pipe with approximately circular cross-section, the inner diameter of that pipe is usually larger than the outer diameter of the reinforcing steel bar leading to unfavorable space inside the concrete section. In addition, the method needs large pipe length, large number of bolts increasing with increasing the bar diameter, leading to higher cost, and difficulty in handling and placing.
DISCLOSURE OF THE INVENTION
The entire disclosure of Egyptian Patent Application No. 2004050224 filed on Jun. 17, 2004 including specifications, claims, drawings, and summary is incorporated herein by reference in its entirety.
This patent application includes the following new elements
- 1—A mechanical coupler for reinforcing bars depends on copying the reinforcing bar deformations (male) on two halves of a coupler or sleeve to form identical grooves (female) in the inner surface of the coupler. The coupler is made of steel or steel alloys by forging, casting, or rolling.
- 2—The coupler halves are assembled along the ends of the two reinforcing bars to be connected assuring the coincidence of the reinforcing bars male deformations with the coupler or sleeve halves female grooves.
- 3—The two coupler or sleeve halves are tightly closed on the two bar connection either by a number of threaded bolts with pre-bored openings in the protruded sides of the two coupler halves, or by a steel pipe with inner diameter form a press fit with the outer diameter of the halves containing the steel bar connection, or by two pipes with inner conical shape pressed at the ends of the two halves.
APPLICATION OF THE PATENT
A mechanical coupler for connecting the ends of two reinforcing bars is made of a sleeve divided into two halves split along its longitudinal axis. Each half is grooved (being a ‘female’) along its inner surface to match with the deformations ‘male’ on the reinforcing bars. The sleeve is adopted to connect the ends of the two ends of reinforcing bars in which the deformations of the reinforcing bars ‘male’ fitted into the grooves ‘female’ made in the inner surface of the sleeve. Three methods are available to tightly close the coupler two halves, as will be explained later.
Making the Connection
- 1—The outer diameter and thickness of the sleeve halves are chosen to be consistent with the reinforcing bars diameter to be connected (the coupler or sleeve inner diameter is equal to the reinforcing bars core diameter without accounting for the existing bar deformations).
- 2—The two ends of the reinforcing bars (1 and 2) to be connected are axially aligned with the male deformations (10) of the two bars enter the female grooves (16) made in the coupler inner surface (FIG. 7 ).
- 3—The two halves of the coupler or sleeve are tightly closed on the two bar ends (1 and 2) by one of the following three methods:
- a. The grooves (16) of the upper and lower halves of the sleeve (13 and 14) are fitted into the reinforcing bars male deformations (10) to grip the two bar ends together. A closure pipe (17) tightly grips the two sleeve halves (13 and 14) together with the inside bars ends (1 and 2) forming intermediate interference fit and achieving a specific pressure value that prevents the two bars from splitting, as shown in FIGS. (7), (8), and (9). (The coupler her mean the two sleeve halves and the closure pipe)
- b. As in FIG. 10, the two halves of the sleeve (18 and 19) with its inside female grooves having an outer surface with gentle slope (20) directed towards the sleeve ends. The two sleeve halves (18 and 19) are assembled along the ends of the two reinforcing bars (1) and (2) to be connected assuring the coincidence of the reinforcing bars male deformations with the sleeve halves female grooves. However two tapered pipe locks (21) and (22) having internal diameter and slope identical to the external diameter and slope of said sleeve halves. The coupling is performed by entering the reinforcing bars male deformations into the said two sleeve halves female grooves then intruding the outer tapered locks (21) and (22) to close the ends of the assembled sleeve halves (18) and (19) and reinforcing bars (1) and (2). (The coupler in this section mean the two sleeve halves and the two tapered pipe locks)
- c. The coupler in FIG. (12) consists of two halves (23) and (24) split along its longitudinal axis. Each half coupler with its inside female grooves having protruded sides. The two reinforcing bars are assembled inside the coupler halves by a number of threaded bolts (25) tied with specific torque preventing the splitting of any of the reinforcing bars from the coupler, as shown in FIG. (12).
Manufacturing the Two Sleeve or Coupler Halves:
A suitable steel alloy or cast steel is chosen to manufacture the coupler or the sleeve by forming it in dimensions suitable for the mechanical coupler and according to the required shape. The coupler is made either by forging, casting, or rolling using either one of the following methods:
1: Forging or Casting:
- In case of manufacturing the coupler by forging or casting, a special mould to form the coupler internally and externally is forged considering the choice of the alloy suitable for each case. The coupler outer surface is processed first according to the closure type of the coupler over the connected bars. Noting that, these two methods are suitable for the methods or coupler assembly presented in the three methods of part 3 of making the connection.
2: Rolling:
- In manufacturing the coupler using rolling, a suitable steel alloy is rolled in suitable dimensions over rollers having male deformations exactly the same as those of the reinforcing bars to be connected forming female grooves in the rolled sections. These sections are cut with suitable lengths accounting for the grooves direction in the coupler halves. (Note: the direction of the grooves in the coupler two halves is an exact image of the male deformations in the reinforcing bars). The outer surface of the coupler is processed according to the method of closing the coupler halves over the reinforcing bars ends. Noting that this method is suitable only for the method of assembly explained in paragraphs (a) and (b) in item (3) of making the connection. FIGS. (7), (8) and (9) shows the two reinforcing bars ends (1) and (2) to be connected by the sleeve halves (13) and (14), whereas the female grooves (16) formed in the two sleeve halves are assembled to form a pipe with internal diameter equals to the outer diameter of the reinforcing bars without the deformations. The protruded end of the coupler (15) is used as stoppage of the cylindrical pipe (17) having specific thickness and internal diameter slightly less than the outer diameter of the coupler two halves with the reinforcing bars ends inside the coupler. The two halves of the sleeve (13) and (14) with the reinforcing bars ends (1) and (2) inside them are tightly closed by entering the pipe (17). Knowing that the pipe inner diameter is slightly less than the outer diameter of the coupler with the reinforcing bars ends inside to form specific internal compression capable of preventing the two reinforcing bars ends from splitting.
The connection shape shown in FIGS. (10) and (11) is resembling that shown in FIG. (7) except for the two sleeve halves (18) and (19) are tapered with gentle slope (20) towards the sleeve ends forming two partial cone at the sleeve ends. The coupler is tightly closed over the two reinforcing bars ends through matching the reinforcing bars male deformations with the sleeve female grooves. An outer tapered pipe locks (21) and (22), having an inner slope matching the original coupler external slope (20), is entered at the first coupler ends with specific axial force achieving pressure that prevents the two reinforcing bars ends from splitting.
FIG. (12) is different from the two previous FIGS. (7) and (11) in the assembly technique which depends in this case in threaded bolts (25) tied with specific torque that prevents the two reinforcing bars ends from splitting out of the coupler, as shown in FIG. (12). The coupler shape in this case is cylindrical after assembly over the two reinforcing bars ends (1) and (2). The coupler also has protruded sides with holes to tie the bolts. It should be noted that the holes in the upper half of the coupler (23) has no threading while the holes in the lower half of the coupler (24) are threaded, as shown in Section (c-c) in FIG. (12).
Manufacturing and Assembly of the Coupler and Sleeve:
- a. A sleeve is chosen as a pipe with internal diameter that equals to the core diameter of the reinforcing bars to be connected without accounting for the reinforcing bars male deformations. The pipe thickness (the solid part between the internal and external diameters of the pipe) is chosen to be proportional to the reinforcing bars diameters.
- b. The pipe is split into two halves along its longitudinal axis.
- c. In case of using forging in copying the reinforcing bars male deformations into the sleeve or coupler halves, the coupler portions need to be heated, and then the male deformations are copied in the inner surface of the two coupler or sleeve halves. In case of making the coupler or sleeve halves using rolling, every portion of the coupler is heated and rolled by the roller having male deformations exactly matching the male deformations of the reinforcing bars to form female grooves in the coupler. Noting that the direction of the female grooves made in the upper half of the coupler or sleeve opposite to the direction of the female grooves made in the lower portion of the coupler or sleeve. The couplers portions are then cut at the designed lengths, so that connecting each two coupler portions on the reinforcing bars will from the required coupler.
- d. A suitable steel material having suitable dimensions is rolled over rollers to finally form a continuous section having the shape of a coupler with internal female grooves identical to the male deformations of the reinforcing bars to be connected. This long section is then cut into couplers of suitable lengths accounting for the directions of the female deformations in the coupler interior. Outer surface slopes are also made as previously described in the third method of assembly.
Coupler Closure Techniques:
First Coupler Closure Technique
- a. The two reinforcing bars to be connected are axially aligned, then the two sleeve halves are assembled around the reinforcing bars ends by matching the bar male deformations with the coupler female grooves.
- b. A special pipe is prepared having an interior diameter equal to the outside diameter of the two sleeve halves with the two reinforcing bars ends inside them and also having a suitable thickness.
- c. The pipe is intruded by compression into the sleeve halves with the connected reinforcing bars inside them.
Second Closure Technique
- The connection shape shown in FIGS. (10) and (11) is resembled as that shown in FIG. (7) except for the two sleeve halves (18) and (19) are tapered with gentle slope (20) towards the sleeve ends forming two partial cones at the sleeve ends. The coupler is tightly closed over the two reinforcing bars ends through matching the reinforcing bars male deformations with the sleeve female grooves. An outer tapered pipe locks (21) and (22), having an inner slope matching the original sleeve external slope (20), is entered from the two sleeve ends with specific axial force achieving pressure that prevents the two reinforcing bars ends from splitting.
Third Closure Technique
In this technique, the coupler assembly depends on threaded bolts (25) that are used in closing the two coupler halves over the two reinforcing bars ends as shown in FIG. (12). It should be noted that the threaded bolt (25) are tied with specific torque that prevents the two reinforcing bars ends from splitting out of the coupler. The coupler shape in this case is cylindrical after assembly over the two reinforcing bars ends (1) and (2). The coupler also has protruded sides with holes to tie the bolts. It should be noted that the holes in the upper half of the coupler (23) has no threading while the holes in the lower half of the coupler (24) are threaded, as shown in Section (c-c) in FIG. (12).
According to the present invention, there provided couplers for connecting the ends of reinforcing bars ends, comprising:
- 1 Reinforcing steel bar 1.
- 2 Reinforcing steel bar 2.
- 3 Welding of Reinforcing steel bar 1 to Reinforcing steel bar 2.
- 4 Additional portion of reinforcing steel bar.
- 5 Cold swaged sleeve coupler.
- 6 Internally threaded collar.
- 7 Two contractible jaws.
- 8 Threaded pin bolt.
- 9 Lock.
- 10 Deformation.
- 11 Interior teeth.
- 12 Projecting deformation.
- 13 Upper half of internally grooved sleeve.
- 14 Lower half of internally grooved sleeve.
- 15 Protruded sleeve end (lip).
- 16 Female grooves.
- 17 Closure pipe.
- 18 Upper half of internally grooved sleeve with tapered ends.
- 19 Lower half of internally grooved sleeve with tapered ends.
- 20 Inclination of the tapered sleeve.
- 21 Right tapered sleeve lock.
- 22 Left tapered sleeve lock.
- 23 Upper half of internally grooved sleeve with protruded sides.
- 24 Lower half of internally grooved sleeve with partially sides.
- 25 Threaded bolts to connect the coupler halves, closure 3.
DRAWING FIGURES
FIG. 1 Splicing the two reinforcing bars then welding.
FIG. 2 Welding the bar ends together then welding two additional bars on the connection sides.
FIG. 3 Cold swaged sleeve coupler.
FIG. 4 Coupler based on internally threaded sleeves and externally threaded reinforcing bars.
FIG. 5 Two jaw assembly includes interior teeth biting into the deformations of steel bars.
FIG. 6 Bar look coupler
FIG. 7 Section of the coupler with the first coupler closure technique.
FIG. 8 Isometric view of a sleeve half having the internal female grooves.
FIG. 9 Exploded view of the coupler with its first closure technique.
FIG. 10 Section of the coupler with the second coupler closure technique.
FIG. 11 Isometric view of the coupler with its second closure technique.
FIG. 12 The coupler with threaded bolts closure technique.
INDUSTRIAL APPLICATION OF THE INVENTION
The patent could be sold to reinforcing steel manufacturing companies or a special factory could be erected to produce the coupler achieving the required quality and specifications for each reinforcing bars diameter accounting for the differences between the steel reinforcing bars produced by different factories, according to the following:
Methods
- a. The outer diameter of the pipe used in manufacturing the coupler is chosen with an internal diameter equal to the reinforcing bar to be connected, noting that the coupler internal diameter is equal to the straight diameter of the reinforcing bar and not the deformation diameter. The thickness (the solid part between the internal and external diameters of the coupler) is proportional to the reinforcing bars diameter. The pipe is split into two equal halves along its longitudinal direction. In case of suing forging or casing to manufacture the coupler, a special mould is made to form the required internal and external shapes of the coupler, using the steel alloy suitable for each case.
- b. The connection shape shown in FIGS. (10) and (11) is resembled as that shown in FIG. (7) except for the two sleeve halves (18) and (19) are tapered with gentle slope (20) towards the sleeve ends forming two partial cones at the sleeve ends. The coupler is tightly closed over the two reinforcing bars ends through matching the reinforcing bars male deformations with the sleeve female grooves. An outer tapered pipe locks (21) and (22), having an inner slope matching the original sleeve external slope (20), is entered from the two sleeve ends with specific axial force achieving pressure that prevents the two reinforcing bars ends from splitting.
- c. In this technique, the coupler assembly depends on threaded bolts (25) that are used in closing the two coupler halves over the two reinforcing bars ends as shown in FIG. (12). It should be noted that the threaded bolt (25) are tied with specific torque that prevents the two reinforcing bars ends from splitting out of the coupler. The coupler shape in this case is cylindrical after assembly over the two reinforcing bars ends (1) and (2). The coupler also has protruded sides with holes to tie the bolts. It should be noted that the holes in the upper half of the coupler (23) has no threading while the holes in the lower half of the coupler (24) are threaded, as shown in Section (c-c) in FIG. (12).
Patent Application
20070248405
