Rubber pulling pipe and steel strand installation construction method and limiting pulling device

Abstract

The invention relates to the technical field of rubber drawing pipe and steel strand installation, in particular to a rubber drawing pipe and steel strand installation construction method and a limiting drawing device. The outer diameter of the end, close to a pressing plate, of an expanding conical ring is smaller than the inner diameter of a stepped groove, and the outer diameter of the other end of the expanding conical ring is larger than the inner diameter of the stepped groove; the diameter-expanding conical ring is pressed on the inner wall of the rubber drawing pipe, and a pull ring is arranged on the outer side of the diameter-expanding conical ring. The steel strand pulling device has the advantages that the stepped groove is formed in the end opening of an existing rubber drawing pipe, the limiting drawing device is arranged in the stepped groove, and the purposes of fixing a steel strand and laterally fixing the end opening of the rubber drawing pipe are achieved through the limiting drawing device; winding limiting of the ends of the steel strands is achieved through the upper inserting rod, relative pressing of the winding ends is achieved through extrusion, the ends of the steel strands are extruded mutually, friction between the steel strands is increased, friction between the steel strands and the upper inserting rod is increased, and therefore the requirement for clamping force is lowered, and clamping stability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of rubber extraction tube and steel strand installation, in particular to a rubber extraction tube and steel strand installation construction method and a position limiting extraction device. Background Art

[0002] During bridge construction or the casting of large prefabricated components, in order to increase the supporting strength, a rubber extraction tube is usually installed in the mold, and a steel strand is installed in the rubber extraction tube. The pre-tensioning force of the steel strand is used to provide an upward supporting force to avoid downward bending and deformation caused by insufficient strength of the large prefabricated components.

[0003] In the prior art, during construction, the rubber extraction tube needs to be lengthened and arranged before installation. When the steel strand is tensioned, the excess rubber extraction tube and the steel strand need to be cut before tensioning. This not only causes waste, but also makes the structure unstable, which reduces the construction efficiency. In addition, the existing steel strand is formed by twisting multiple steel wires, and its outer wall is spiral, resulting in a small contact area during the pre-tightening and clamping process, and a large clamping force is required to achieve stable clamping without falling off. Summary of the invention

[0004] The purpose of the present invention is to provide a rubber extraction tube and a steel strand installation construction method and a position limiting extraction device to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A rubber extraction pipe and a steel strand installation construction method, the construction method comprising the following steps:

[0007] Step 1: Clamp the two ends of the rubber extraction tube and the steel strand through the limit extraction device;

[0008] Step 2: Use the tensioning device to pull the limit extraction device on one side to pre-tighten the tension of the steel strand.

[0009] The invention discloses a position limiting extraction device for the installation and construction of a rubber extraction tube and a steel strand, comprising a position limiting extraction device, which is used in the installation and construction method of the rubber extraction tube and the steel strand, wherein the position limiting extraction device is installed in the anchor holes at both ends of the casting, and the anchor hole port position is provided with an anchor sleeve, and a rubber extraction tube is sleeved through the anchor sleeve, and a plurality of groups of steel strands distributed in a circumferential array are provided in the rubber extraction tube.

[0010] Step grooves are provided at both ends of the rubber extraction tube, and the ends of the rubber extraction tube extend to the outside of the port of the anchor sleeve. The limiting extraction device includes a sleeve plate, a pressure plate and an expansion cone ring. The sleeve plate is pressed on the step surface of the step groove, and the steel strand passes through the sleeve plate. A plurality of upper plug rods corresponding to the steel strands are provided on the sleeve plate. The steel strands are wound along the upper plug rods, and a positioning sleeve for fixing the ends of the steel strands is provided on the ends of the upper plug rods. The pressure plate is inserted and pressed on the sleeve plate, and a pressure groove for squeezing the upper plug rod is provided on the pressure plate. The other end of the pressure plate is connected to the expansion cone ring through a connecting rod, and the outer diameter of the expansion cone ring close to the pressure plate is smaller than the inner diameter of the step groove, and the outer diameter of the other end of the expansion cone ring is larger than the inner diameter of the step groove. The expansion cone ring is pressed on the inner wall of the rubber extraction tube, and a pull ring is provided on the outside of the expansion cone ring.

[0011] Preferably, the expanding cone ring is rotatably mounted on the connecting rod, and limiting nuts and sleeves are respectively provided on both sides of the expanding cone ring, the limiting nuts and sleeves are both sleeved on the connecting rod, a rotating wheel is provided at the end of the connecting rod, and a pull ring is provided on the outer end face of the rotating wheel.

[0012] Preferably, the end of the anchor sleeve is provided with an inner bevel ring fixed with screws, the inner side of the upper end of the inner bevel ring is provided with an inclined surface, and the inner diameter of the inner bevel ring is equal to the outer diameter of the rubber extraction tube, and the outer wall of the rubber extraction tube port is pressed onto the inclined surface of the inner bevel ring under the extrusion of the expansion cone ring.

[0013] Preferably, the positioning sleeve is provided with a through hole extending perpendicularly to the upper insertion rod, and the end of the steel strand is inserted into the through hole.

[0014] Preferably, the sleeve plate is provided with a through slot for accommodating the steel strands to pass through and plug in, and a pressing ring is provided at the lower end of the pressing plate, and the lower end of the pressing ring is directly opposite to the gap between the upper insertion rod and the through slot.

[0015] Preferably, a slide plate is slidably sleeved on the upper insertion rod, the slide plate is located on the outside of the sleeve plate, a spring is provided at the lower end of the slide plate, the spring is sleeved on the upper insertion rod, the spring is pressed between the slide plate and the sleeve plate, and the steel strand is wound along the outside of the slide plate.

[0016] Preferably, a bottom plate is provided at one end of the upper plug rod away from the positioning sleeve, a lower plug rod is provided on the bottom plate, and a positioning hole for cooperating and plugging with the lower plug rod is provided on the stepped surface of the stepped groove.

[0017] Preferably, a socket is provided in the middle of the sleeve plate, a threaded inner groove is provided at the inner end of the socket, a plug is provided on the pressure plate and is plugged into the socket, and an external thread is provided at the end of the plug that cooperates with the threaded inner groove for threaded rotation.

[0018] Preferably, a top ring located outside the through groove is provided on the end surface of the sleeve plate, and the steel strand is smoothly bent along the top ring and wound around the upper insertion rod.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a stepped groove at the port of an existing rubber extraction tube and a limit extraction device in the stepped groove. The limit extraction device is used to fix the steel strand and laterally fix the port of the rubber extraction tube. An upper insertion rod is used to limit the winding of the end of the steel strand, and extrusion is used to achieve relative pressing of the winding ends, so that the ends of the steel strands are squeezed against each other, which increases the friction between the steel strands and the friction between the steel strands and the upper insertion rod, thereby reducing the requirements for the clamping force and improving the stability of the clamping. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention;

[0022] Figure 2 It is a schematic diagram of the steel strand clamping and fastening structure of the present invention;

[0023] Figure 3 It is a schematic diagram of the steel strand winding structure of the present invention;

[0024] Figure 4 It is a schematic diagram of the three-dimensional structure of the sleeve plate of the present invention;

[0025] Figure 5 It is a schematic diagram of the three-dimensional structure of the connection between the pressing plate and the expanded cone ring of the present invention;

[0026] Figure 6 It is a schematic diagram of the fixed clamping three-dimensional structure on the expanded diameter cone ring connecting rod of the present invention.

[0027] In the figure: 1. Anchor hole; 2. Rubber extraction tube; 3. Anchor sleeve; 4. Step groove; 5. Steel strand; 6. Bushing; 7. Pressure plate; 8. Connecting rod; 9. Expanding cone ring; 10. Rotor; 11. Pull ring; 12. Limit nut; 13. Bushing; 14. Inner bevel ring; 15. Positioning sleeve; 16. Lower plug rod; 17. Positioning hole; 18. Bottom plate; 19. Upper plug rod; 20. Spring; 21. Plug column; 22. Plug hole; 23. Threaded inner groove; 24. Pressure groove; 25. Pressure ring; 26. Slide plate; 27. Through groove; 28. Top ring; 29. ​​External thread. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figures 1 to 6, the present invention provides a technical solution:

[0030] A rubber extraction pipe and a steel strand installation construction method, the construction method comprising the following steps:

[0031] Step 1: Clamp the two ends of the rubber extraction tube 2 and the steel strand 5 by means of a limit extraction device;

[0032] Step 2: Pre-tighten the tension of the steel strand 5 by pulling the limit extraction device on one side through the tensioning device.

[0033] Embodiment 1: A position limiting extraction device for the installation and construction of a rubber extraction tube and a steel strand comprises a position limiting extraction device, which is installed in an anchor hole 1 at both ends of a cast part, an anchor sleeve 3 is provided at the end position of the anchor hole 1, a rubber extraction tube 2 is inserted through the anchor sleeve 3, and a plurality of groups of steel strands 5 distributed in a circular array are provided in the rubber extraction tube 2.

[0034] Step grooves 4 are provided at both ends of the rubber extraction tube 2, and the ends of the rubber extraction tube 2 extend to the outside of the port of the anchor sleeve 3. The limiting extraction device includes a sleeve plate 6, a pressure plate 7 and an expansion cone ring 9. The sleeve plate 6 is pressed on the step surface of the step groove 4, and the steel strand 5 passes through the sleeve plate 6.

[0035] The purpose of limiting the position of the steel strand 5 is achieved by providing the sleeve plate 6 .

[0036] The sleeve plate 6 is provided with a plurality of groups of upper insertion rods 19 corresponding to the steel strands 5 one by one. The steel strands 5 are wound along the upper insertion rods 19 . The ends of the upper insertion rods 19 are provided with positioning sleeves 15 for fixing the ends of the steel strands 5 .

[0037] By providing the upper insertion rod 19 and the positioning sleeve 15, the winding and fixing of the end of the steel strand 5 is achieved.

[0038] The pressing plate 7 is inserted and pressed on the sleeve plate 6. The pressing plate 7 is provided with a pressing groove 24 for squeezing the upper insertion rod 19. By inserting the pressing plate 7, the pressing groove 24 is pressed on the upper insertion rod 19, driving the upper insertion rod 19 to slide to one side of the sleeve plate 6, so that the gap between the spirally wound steel strands 5 is reduced. With continuous squeezing, the spirally wound steel strands 5 are squeezed and pressed against each other, thereby increasing the friction between the steel strands 5, preventing the steel strands 5 from falling off during pre-tensioning.

[0039] The other end of the pressure plate 7 is connected to the expanding cone ring 9 through a connecting rod 8. The outer diameter of one end of the expanding cone ring 9 close to the pressure plate 7 is smaller than the inner diameter of the stepped groove 4, and the outer diameter of the other end of the expanding cone ring 9 is larger than the inner diameter of the stepped groove 4. The expanding cone ring 9 is pressed onto the inner wall of the rubber extraction tube 2, and a pull ring 11 is provided on the outer side of the expanding cone ring 9.

[0040] During the pressing process of the pressure plate 7, the expanding cone ring 9 is inserted into the port of the rubber extraction tube 2. As the outer diameter of the expanding cone ring 9 gradually increases, the outer wall of the port of the rubber extraction tube 2 is deformed outward and tightly pressed against the inner wall of the anchor sleeve 3, thereby achieving the purpose of fixing the end of the rubber extraction tube 2.

[0041] Working principle: First, the stepped groove 4 is provided to facilitate the plug-in installation of the sleeve plate 6 and the pressure plate 7, and the sleeve plate 6 is used to achieve the purpose of limiting the position of the steel strand 5. The upper plug rod 19 and the positioning sleeve 15 are provided to realize the winding and fixation of the end of the steel strand 5. The upper plug rod 19 slides under the plug-in extrusion of the pressure plate 7, and then the spirally wound steel strand 5 is driven to slide relatively under the extrusion of the positioning sleeve 15. With the continuous extrusion, the spirally wound steel strands 5 are squeezed and pressed against each other, thereby increasing the friction between the steel strands 5 and preventing the steel strands 5 from falling off during pre-tensioning.

[0042] While the pressure plate 7 is pressed together, the expanding cone ring 9 is inserted into the port of the rubber extraction tube 2. As the conical surface of the expanding cone ring 9 is inserted and extruded, the outer diameter of the port of the rubber extraction tube 2 increases, and the outer wall of the port of the rubber extraction tube 2 is deformed, thereby forming an extrusion fixation, and then the limiting extraction device is clamped at both ends of the rubber extraction tube 2 and the steel strand 5, thereby eliminating the need for lengthening and pre-reservation, and facilitating subsequent tensioning and pre-tightening.

[0043] Example 2: On the basis of Example 1, the expanding cone ring 9 is rotatably installed on the connecting rod 8, and a limiting nut 12 and a shaft sleeve 13 are respectively provided on both sides of the expanding cone ring 9. The limiting nut 12 and the shaft sleeve 13 are both sleeved on the connecting rod 8. A rotating wheel 10 is provided at the end of the connecting rod 8, and a pull ring 11 is provided on the outer end face of the rotating wheel 10.

[0044] By setting the limit nut 12 and the sleeve 13, the expansion cone ring 9 is clamped, thereby driving the expansion cone ring 9 and the pressure plate 7 to move as a whole. However, for the end that needs to be tensioned and pulled, there is no need to install the limit nut 12, which facilitates the extension of the pulling steel strand 5 during the tensioning process.

[0045] Example 3: On the basis of Example 2, an inner bevel ring 14 fixed with screws is provided at the end of the anchor sleeve 3, an inclined surface is provided on the inner side of the upper end of the inner bevel ring 14, and the inner diameter of the inner bevel ring 14 is equal to the outer diameter of the rubber extraction tube 2, and the outer wall of the port of the rubber extraction tube 2 is pressed onto the inclined surface of the inner bevel ring 14 under the extrusion of the expansion cone ring 9.

[0046] The inner bevel ring 14 is provided to support the outer wall of the port of the deformed rubber extraction tube 2 , so that the outer wall of the port of the rubber extraction tube 2 is clamped inside and outside by the cooperation of the inclined surface of the inner bevel ring 14 and the tapered outer wall of the expanded cone ring 9 .

[0047] The positioning sleeve 15 is provided with a through hole extending perpendicularly to the upper insertion rod 19, and the end of the steel strand 5 is inserted in the through hole. The sleeve plate 6 is provided with a through groove 27 for accommodating the steel strand 5 to pass through and insert. The lower end of the pressure plate 7 is provided with a pressing ring 25, and the lower end of the pressing ring 25 is opposite to the gap between the upper insertion rod 19 and the through groove 27.

[0048] By setting vertically distributed through holes, the vertical bending, extension and plug-in fixation of the end of the steel strand 5 can be achieved. By setting the through groove 27, the position where the strand 5 passes through is limited to avoid lateral deviation. During the downward pressing process of the positioning sleeve 15, the spirally extended steel strand 5 slides relatively and fits together. At this time, the length of the steel strand 5 extending between the upper insertion rod 19 and the through groove 27 is increased. By squeezing the pressure ring 25, the steel strand 5 extending between the upper insertion rod 19 and the through groove 27 is bent and extended downward to maintain a taut state.

[0049] Example 4: Based on Example 3, a slide plate 26 is slidably sleeved on the upper insertion rod 19, and the slide plate 26 is located on the outside of the sleeve plate 6. A spring 20 is provided at the lower end of the slide plate 26. The spring 20 is sleeved on the upper insertion rod 19, and the spring 20 is pressed between the slide plate 26 and the sleeve plate 6. The steel strand 5 is wound along the outside of the slide plate 26.

[0050] By setting the cooperation of the slide plate 26 and the spring 20, elastic support for the upper insertion rod 19 is achieved, and the spirally wound steel strand 5 is supported, so that when the upper insertion rod 19 is squeezed, elastic deformation is achieved, and automatic reset is achieved by utilizing the reset force of the spring 20 during disassembly.

[0051] A bottom plate 18 is provided at one end of the upper plug rod 19 away from the positioning sleeve 15, and a lower plug rod 16 is provided on the bottom plate 18. A positioning hole 17 for cooperating with the lower plug rod 16 is provided on the stepped surface of the stepped groove 4. A plug hole 22 is provided in the middle of the sleeve plate 6, and a threaded inner groove 23 is provided at the inner end of the plug hole 22. A plug column 21 inserted into the plug hole 22 is provided on the pressure plate 7, and an external thread 29 is provided at the end of the plug column 21 for threaded rotation cooperating with the threaded inner groove 23.

[0052] By setting the matching of the plug column 21 and the plug hole 22, the sliding insertion of the pressure plate 7 on the sleeve plate 6 is realized, and the matching of the inner thread groove 23 and the outer thread 29 is utilized to realize the purpose of fixed connection between the pressure plate 7 and the sleeve plate 6 through thread rotation after insertion. The lower plug rod 16 and the positioning hole 17 are matched and inserted through sliding extrusion insertion, thereby avoiding the sleeve plate 6 from rotating during the subsequent thread rotation process.

[0053] A top ring 28 located outside the through groove 27 is provided on the end surface of the sleeve plate 6 , and the steel strand 5 is smoothly bent along the top ring 28 and wound around the upper insertion rod 19 .

[0054] The top ring 28 is provided to achieve smooth bending of the steel strand 5 and avoid breakage caused by excessive extrusion.

[0055] In the actual construction process, the pre-tensioning steps include: Step 1: Opening step grooves 4 at both ends of the rubber extraction tube 2, plugging and installing the sleeve plate 6, so that the steel strands 5 pass through the sleeve plate 6, and bending the multiple groups of steel strands 5 in the opposite direction and winding them on the upper insertion rod 19;

[0056] Step 2: The pressure plate 7 is inserted into the stepped groove 4 and pressed onto the upper insertion rod 19 through the pull ring 11. At this time, one end of the expanding cone ring 9 is inserted into the port of the rubber extraction tube 2. During the insertion process, the port of the rubber extraction tube 2 is squeezed along the inclined cone surface of the expanding cone ring 9 and deformed and expanded outward;

[0057] Step 3: The threaded rotation of the plug post 21 in the plug hole 22 further presses the pressing plate 7 onto the sleeve plate 6, and the spirally wound steel strands 5 are pressed and tightened by extrusion, while the expanding cone ring 9 laterally extrudes and fixes the port of the rubber extraction tube 2;

[0058] Step 4: For the end that needs prestressing, the limit nut 12 is not installed. The traction device and the pull ring 11 are used to drive the connecting rod 8 to slide outward, driving the pressure plate 7 and the sleeve plate 6 to slide, thereby pulling the end of the steel strand 5 for tensioning, thereby pre-tightening the steel strand 5.

[0059] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Installation and construction method of rubber extraction tube and steel strand, Features: The construction method comprises the following steps: Step 1: clamping the two ends of the rubber extraction tube (2) and the steel strand (5) by means of a position limiting extraction device; Step 2: Pre-tightening the tension of the steel strand (5) is achieved by pulling the limit extraction device on one side through the tensioning device.

2. A position limiting extraction device for the installation and construction of a rubber extraction tube and a steel strand, comprising a position limiting extraction device, the position limiting extraction device being used in the installation and construction method of the rubber extraction tube and the steel strand as claimed in claim 1, the position limiting extraction device being installed in the anchor holes (1) at both ends of the cast part, the end position of the anchor hole (1) being provided with an anchor sleeve (3), the anchor sleeve (3) being penetrated and sleeved with a rubber extraction tube (2), the rubber extraction tube (2) being provided with a plurality of groups of steel strands (5) distributed in a circumferential array, Features: The two ends of the rubber extraction tube (2) are provided with stepped grooves (4), and the ends of the rubber extraction tube (2) extend to the outside of the port of the anchor sleeve (3). The position limiting extraction device comprises a sleeve plate (6), a pressure plate (7) and an expansion cone ring (9). The sleeve plate (6) is pressed on the stepped surface of the stepped groove (4), and the steel strand (5) passes through the sleeve plate (6). The sleeve plate (6) is provided with a plurality of upper insertion rods (19) corresponding to the steel strands (5) one by one. The steel strands (5) are wound along the upper insertion rods (19), and the ends of the upper insertion rods (19) are provided with fixing members for fixing the steel strands (5). ) at the end thereof, the pressure plate (7) is inserted and pressed onto the sleeve plate (6), a pressing groove (24) for squeezing the upper insert rod (19) is provided on the pressure plate (7), the other end of the pressure plate (7) is connected to the expanding cone ring (9) through a connecting rod (8), the outer diameter of one end of the expanding cone ring (9) close to the pressure plate (7) is smaller than the inner diameter of the stepped groove (4), the outer diameter of the other end of the expanding cone ring (9) is larger than the inner diameter of the stepped groove (4), the expanding cone ring (9) is pressed onto the inner wall of the rubber extraction tube (2), and a pull ring (11) is provided on the outer side of the expanding cone ring (9).

3. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 2, Features: The expanding cone ring (9) is rotatably mounted on the connecting rod (8), and a limiting nut (12) and a shaft sleeve (13) are respectively arranged on both sides of the expanding cone ring (9), and the limiting nut (12) and the shaft sleeve (13) are both sleeved on the connecting rod (8). A rotating wheel (10) is arranged at the end of the connecting rod (8), and a pull ring (11) is arranged on the outer end surface of the rotating wheel (10).

4. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 3, Features: The end of the anchor sleeve (3) is provided with an inner bevel ring (14) fixed by screws, the inner side of the upper end of the inner bevel ring (14) is provided with an inclined surface, and the inner diameter of the inner bevel ring (14) is equal to the outer diameter of the rubber extraction tube (2), and the outer wall of the port of the rubber extraction tube (2) is pressed onto the inclined surface of the inner bevel ring (14) under the extrusion of the expansion cone ring (9).

5. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 2, Features: The positioning sleeve (15) is provided with a through hole extending perpendicularly to the upper insertion rod (19), and the end of the steel strand (5) is inserted into the through hole.

6. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 5, Features: The sleeve plate (6) is provided with a through slot (27) for accommodating the steel strand (5) to pass through and be inserted therein, and a pressing ring (25) is provided at the lower end of the pressing plate (7), wherein the lower end of the pressing ring (25) is directly opposite to the gap between the upper insertion rod (19) and the through slot (27).

7. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 6, Features: A slide plate (26) is slidably sleeved on the upper insertion rod (19), the slide plate (26) is located on the outer side of the sleeve plate (6), a spring (20) is arranged at the lower end of the slide plate (26), the spring (20) is sleeved on the upper insertion rod (19), the spring (20) is pressed between the slide plate (26) and the sleeve plate (6), and the steel strand (5) is wound along the outer side of the slide plate (26).

8. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 7, Features: A bottom plate (18) is provided at one end of the upper insertion rod (19) away from the positioning sleeve (15), a lower insertion rod (16) is provided on the bottom plate (18), and a positioning hole (17) for mating with the lower insertion rod (16) is provided on the stepped surface of the stepped groove (4).

9. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 8, Features: The sleeve plate (6) is provided with an insertion hole (22) in the middle, and the inner end of the insertion hole (22) is provided with a threaded inner groove (23). The pressure plate (7) is provided with an insertion column (21) inserted into the insertion hole (22), and the end of the insertion column (21) is provided with an external thread (29) that rotates in cooperation with the threaded inner groove (23).

10. The rubber extraction tube and the limit extraction device for installation and construction of steel strands according to claim 7, Features: A top ring (28) located outside the through groove (27) is arranged on the end surface of the sleeve plate (6), and the steel strand (5) is smoothly bent along the top ring (28) and wound around the upper insertion rod (19).

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