Prestressed reinforced concrete pipe steel bar prestress tension device

Abstract

The application discloses a prestressed reinforced concrete pipe steel bar prestress tension device and relates to the technical field of prestress tension. The device comprises a fixed frame, a rotating assembly arranged above the fixed frame, a concrete pipe arranged above the rotating assembly, and a feeding assembly arranged on the side of the fixed frame. The feeding assembly comprises a mounting frame, a conveying belt arranged above the mounting frame, a conveying motor arranged at the end of the mounting frame, and an output shaft of the conveying motor connected with the conveying belt through a belt wheel pair. A sleeve is fixed to the side of the mounting frame, two guide blocks are arranged above the sleeve, a rotating roller is rotatably arranged in the sleeve, a plurality of conveying holes are formed in the rotating roller, a limiting hole is formed in one end of the rotating roller, an electric push rod is fixed below the sleeve, a fixed plate is fixed to the end of the electric push rod, and a limiting assembly is arranged at the two ends of the fixed frame. The device can ensure the conveying and fixing precision of the steel bar and effectively avoid the bending or deviation of the steel bar.

Description

Technical Field

[0001] This invention relates to the field of prestressing tensioning technology, specifically to a prestressing tensioning device for prestressed reinforced concrete pipe reinforcement. Background Technology

[0002] Prestressed reinforced concrete pipes (PCCPs) are widely used in large-scale infrastructure projects such as long-distance water and gas transmission due to their high strength, corrosion resistance, and impermeability. Their core manufacturing process involves applying prestress to multiple high-strength steel bars wound around a concrete core using a prestressing tensioning device to enhance the pipe's load-bearing capacity.

[0003] Traditional prestressed tensioning devices face the following technical bottlenecks in the simultaneous feeding of multiple reinforcing bars: Traditional devices often use a method of independent positioning and tensioning of a single reinforcing bar, requiring repeated adjustments to the bar's position, resulting in a slow production cycle and difficulty in meeting the needs of large-scale production; When multiple reinforcing bars are fed in parallel, due to the limited rigidity of the reinforcing bars themselves (especially when the length-to-diameter ratio is large), they are prone to sagging and bending under gravity, friction, or external interference; At the same time, the lack of a precise guiding mechanism leads to fluctuations in the spacing between the reinforcing bars, affecting the efficiency of subsequent prestressing tensioning. Summary of the Invention

[0004] The purpose of this invention is to provide a prestressed tensioning device for prestressed reinforced concrete pipe reinforcement to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a prestressed reinforced concrete pipe prestressing tensioning device, comprising a fixed frame, a rotating assembly above the fixed frame, a concrete pipe above the rotating assembly, a feeding assembly on the side of the fixed frame, the feeding assembly comprising an installation frame, a conveyor belt above the installation frame, a conveyor motor at the end of the installation frame, the output shaft of the conveyor motor being connected to the conveyor belt via a pulley pair, a sleeve fixed on the side of the installation frame, two guide blocks above the sleeve, a rotating roller rotatably mounted inside the sleeve, the rotating roller having several conveying holes, a limit hole at one end of the rotating roller, an electric push rod fixed below the sleeve, a fixed plate fixed at the end of the electric push rod, a rotary motor fixed on one side of the fixed plate, a limit shaft fixed on the output shaft of the rotary motor, the limit shaft being located on the other side of the fixed plate, the limit shaft being slidably mounted inside the limit hole, several extrusion rods fixed on the other side of the fixed plate, the extrusion rods being shorter than the limit shaft, and limiting assemblies at both ends of the fixed frame.

[0006] The concrete pipe has several pre-reserved holes, and the other end of the rotating roller extends out of the sleeve.

[0007] The feeding assembly also includes a mounting frame and two moving motors. The mounting frame is fixed to the end of the mounting bracket. Inside the mounting frame, there are four connecting plates 1 and four connecting plates 2. The connecting plates 1 and 2 are perpendicular to each other. A drive shaft is rotatably mounted on two adjacent connecting plates 1. One end of the drive shaft extends through the mounting frame. A driven shaft is rotatably mounted on two adjacent connecting plates 2. The driven shaft and the drive shaft are connected by a bevel gear pair. The moving motors are fixed to the mounting frame. The output shaft of the moving motors is connected to the drive shaft through a coupling. A conveyor wheel 2 is fixed on the driven shaft. A conveyor wheel 1 is fixed on the drive shaft. Both the conveyor wheel 1 and the conveyor wheel 2 are located at corresponding limiting holes.

[0008] With the above structure, the moving motor drives the drive shaft to rotate, which in turn drives the driven shaft to rotate synchronously through the bevel gear pair. The first and second conveyor wheels on the drive and driven shafts contact the surface of the reinforcing bars, and the friction force pushes the reinforcing bars to move towards the reserved holes in the concrete pipe. The bevel gear pair enables the drive shaft and driven shaft to rotate synchronously at 90°, ensuring that the conveying speed of the two reinforcing bars is consistent and avoiding changes in spacing. The vertically arranged connecting plates optimize space utilization, reduce the footprint of the device, and are suitable for narrow production environments.

[0009] The rotating assembly includes two base plates and two rotating motors. Both base plates are fixed inside the fixed frame. A rotating frame is fixed above the base plates. Support wheels are fixed at both ends of the rotating frame. The rotating motors are fixed above the base plates and drive the support wheels to rotate through a gear pair.

[0010] With the above structure, the rotating motor drives the support wheel to rotate through the gear pair. The support wheel contacts the rotating frame, causing the concrete pipe to rotate around the axis. The two support wheels clamp the rotating frame from both sides, forming a stable support structure to prevent the concrete pipe from being eccentric or swaying when rotating.

[0011] The limiting component includes two mounting plates, which are respectively fixed to both ends of the mounting frame, and through holes are provided on the top of the mounting plates.

[0012] With the above structure, the mounting plate is fixed at both ends of the mounting frame, and the through hole on it provides a guide channel for the steel bar, restricting the lateral movement range of the steel bar and ensuring that the steel bar enters the reserved hole along the preset path; the diameter of the through hole matches the diameter of the steel bar, preventing the steel bar from deviating from the target position due to bending or external force during the feeding process. The through hole of the mounting plate is used directly to achieve the limit, without the need for additional complex mechanisms, reducing costs and maintenance difficulty.

[0013] The limiting component also includes two mounting posts, with several support legs fixed to the ends of the mounting posts. The support legs are arranged in a cross shape, and each support leg has a rotatable wheel at its end. Both support legs have ratchet grooves inside, and the same rotating cylinder is rotatably installed inside the two support legs. A push-type cylindrical lock is installed inside the rotating cylinder, and the lock cylinder of the push-type cylindrical lock has ratchet teeth at its end. A tightening motor is fixed on the support leg, and the output shaft of the tightening motor is fixedly connected to the rotating cylinder.

[0014] With the above structure, the movable wheels at the ends of the support legs allow the entire device to move, making it easy to adjust the position to adapt to different production scenarios; the tightening motor drives the rotating cylinder to rotate, and the tightening band is wrapped around the rotating cylinder. The ratchet and ratchet grooves work together to achieve one-way locking, preventing the support legs from moving in the opposite direction. The combination of the ratchet and ratchet structure and the tightening band achieves double fixation of the steel bars, preventing the steel bars from loosening or falling off during the feeding process.

[0015] Several placement plates are fixed between the support legs. Limiting blocks are fixed on the placement plates. Placement slots are opened above the limiting blocks. Moving holes are opened on the limiting blocks. Tightening straps are fixed on the limiting blocks. The end of the tightening strap passes through the moving hole and is fixed to the rotating cylinder. A spring telescopic rod is provided inside the limiting block. A support block is fixed to the end of the spring telescopic rod.

[0016] With the above structure, after the reinforcing bar is placed in the placement slot of the limiting block, the tightening belt tightens under the drive of the rotating cylinder, clamping the reinforcing bar; the spring telescopic rod pushes the support block to press against the reinforcing bar, providing elastic compensation; pressing the press-type cylindrical lock can disengage the ratchet from the ratchet groove, realizing the rapid release of the tightening belt; the tightening motor realizes the automatic tensioning and release of the tightening belt, reducing manual intervention and improving production efficiency.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] By replacing manual handling and positioning with mechanical transmission, production efficiency is significantly improved. The installation plate through holes, limit block placement slots and one-way locking mechanism ensure the accuracy of steel bar delivery and fixing, effectively preventing steel bar bending or displacement. At the same time, the modular design and compact layout reduce space occupation and maintenance costs, and are compatible with the production needs of multiple specifications of steel bars and concrete pipes, providing an efficient, stable and low-cost automated solution for prestressed concrete pipe manufacturing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the upper three-dimensional structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the lower three-dimensional structure of the present invention;

[0021] Figure 3This is a front view structural diagram of the present invention;

[0022] Figure 4 This is a side view of the conveying component in this invention.

[0023] Figure 5 This is a front view of the conveying component in this invention.

[0024] Figure 6 for Figure 4 Enlarged structural diagram at point A;

[0025] Figure 7 This is a three-dimensional structural diagram of the limiting component in this invention;

[0026] Figure 8 This is a cross-sectional structural diagram of the limiting component in this invention.

[0027] In the diagram: 1. Concrete pipe; 2. Mounting plate; 3. Fixing frame; 4. Mounting bracket; 5. Conveyor belt; 6. Pre-drilled hole; 7. Rotating frame; 8. Base plate; 9. Support wheel; 10. Rotating motor; 11. Conveyor motor; 12. Reinforcing bar; 13. Rotating roller; 14. Extrusion rod; 15. Rotating motor; 16. Fixing plate; 17. Limiting shaft; 18. Electric push rod; 19. Sleeve; 20. Guide block; 21. Mounting frame; 22. Moving... 23. Driven shaft; 24. Bevel gear pair; 25. Connecting plate one; 26. Conveyor wheel one; 27. Drive shaft; 28. Conveyor wheel two; 29. ​​Support block; 30. Tightening motor; 31. Tightening belt; 32. Placement plate; 33. Racket; 34. Press-type cylindrical lock; 35. Rotating cylinder; 36. Mounting column; 37. Moving wheel; 38. Limit block; 39. Moving hole; 40. Spring telescopic rod; 41. Support leg. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] like Figures 1-8As shown, the present invention provides a technical solution: a prestressed reinforced concrete pipe rebar prestressing tensioning device, including a fixed frame 3, a rotating assembly above the fixed frame 3, a concrete pipe 1 above the rotating assembly, a feeding assembly on the side of the fixed frame 3, the feeding assembly including a mounting frame 4, a conveyor belt 5 above the mounting frame 4, a conveyor motor 11 at the end of the mounting frame 4, the output shaft of the conveyor motor 11 being connected to the conveyor belt 5 via a pulley pair, a fixed sleeve 19 on the side of the mounting frame 4, two guide blocks 20 above the sleeve 19, and the interior of the sleeve 19... A rotating roller 13 is rotatably mounted, and several conveying holes are opened on the rotating roller 13. A limit hole is opened at one end of the rotating roller 13. An electric push rod 18 is fixed below the sleeve 19. A fixing plate 16 is fixed at the end of the electric push rod 18. A rotary motor 15 is fixed on one side of the fixing plate 16. A limit shaft 17 is fixed on the output shaft of the rotary motor 15. The limit shaft 17 is located on the other side of the fixing plate 16 and is slidably mounted inside the limit hole. Several extrusion rods 14 are fixed on the other side of the fixing plate 16. The extrusion rods 14 are shorter than the limit shaft 17. Limiting components are provided at both ends of the fixing frame 3.

[0030] Several pre-reserved holes 6 are opened on the concrete pipe 1, and the other end of the rotating roller 13 extends out of the sleeve 19;

[0031] The feeding assembly also includes a mounting frame 21 and two moving motors 22. The mounting frame 21 is fixed to the end of the mounting bracket 4. Inside the mounting frame 21, four connecting plates 1 25 and four connecting plates 2 are fixed. The connecting plates 1 25 and connecting plates 2 are perpendicular to each other. A drive shaft 27 is rotatably mounted on two adjacent connecting plates 1 25. One end of the drive shaft 27 extends through the mounting frame 21. A driven shaft 23 is rotatably mounted on two adjacent connecting plates 2. The driven shaft 23 and the drive shaft 27 are connected by a bevel gear pair 24. The moving motors 22 are fixed to the mounting frame 21. The output shaft of the moving motor 22 is connected to the drive shaft 27 through a coupling. A conveyor wheel 28 is fixed on the driven shaft 23. A first conveyor wheel 26 is fixed, and both the first conveyor wheel 26 and the second conveyor wheel 28 are located at corresponding limiting holes. The moving motor 22 drives the drive shaft 27 to rotate, which drives the driven shaft 23 to rotate synchronously through the bevel gear pair 24. The first conveyor wheel 26 and the second conveyor wheel 28 on the drive shaft 27 and the driven shaft 23 are in contact with the surface of the steel bar 12, and the friction pushes the steel bar 12 to move towards the reserved hole 6 of the concrete pipe 1. The bevel gear pair 24 realizes the synchronous rotation of the drive shaft 27 and the driven shaft 23 at a 90° turn, ensuring that the conveying speed of the two steel bars 12 is consistent and avoiding changes in spacing. The vertically arranged connecting plate 25 and the second connecting plate optimize space utilization, reduce the footprint of the device, and are suitable for narrow production environments.

[0032] The rotating assembly includes two base plates 8 and two rotating motors 10. Both base plates 8 are fixed inside the fixed frame 3. A rotating frame 7 is fixed above the base plates 8. Support wheels 9 are fixed at both ends of the rotating frame 7. The rotating motors 10 are fixed above the base plates 8. The rotating motors 10 drive the support wheels 9 to rotate through a gear pair. The rotating motors 10 drive the support wheels 9 to rotate through the gear pair. The support wheels 9 contact the rotating frame 7, causing the concrete pipe 1 to rotate around the axis. The two support wheels 9 clamp the rotating frame 7 from both sides to form a stable support structure, preventing the concrete pipe 1 from being eccentric or swaying when rotating.

[0033] The limiting component includes two mounting plates 2, which are fixed to both ends of the mounting frame 21. Through holes are provided on the top of the mounting plates 2. The mounting plates 2 are fixed to both ends of the mounting frame 21, and the through holes on them provide a guide channel for the reinforcing bars 12, limiting the lateral movement range of the reinforcing bars 12 and ensuring that the reinforcing bars 12 enter the reserved holes 6 along the preset path. The diameter of the through holes matches the diameter of the reinforcing bars 12, preventing the reinforcing bars 12 from deviating from the target position due to bending or external force during the feeding process. The limiting is achieved directly by using the through holes of the mounting plates 2, without the need for additional complex mechanisms, reducing costs and maintenance difficulty.

[0034] The limiting assembly also includes two mounting posts 36, with several support legs 41 fixed to the ends of the mounting posts 36. These support legs 41 are arranged in a cross shape, and each support leg 41 has a rotatable caster 37 at its end. Each support leg 41 has a ratchet groove inside, and a common rotating cylinder 35 is rotatably mounted inside both support legs 41. A push-button cylindrical lock 34 is installed inside the rotating cylinder 35, and a ratchet 33 is provided at the end of the lock cylinder of the push-button cylindrical lock 34. A tightening motor 30 is fixed to the support leg 41. The output shaft of the tightening motor 30 is fixedly connected to the rotating cylinder 35; the movable wheel 37 at the end of the support leg 41 allows the device to move as a whole, making it easy to adjust the position to adapt to different production scenarios; the tightening motor 30 drives the rotating cylinder 35 to rotate, and the tightening band 31 is wrapped around the rotating cylinder 35. The ratchet 33 and the ratchet groove cooperate to achieve one-way locking, preventing the support leg 41 from moving in the opposite direction. The combination of the ratchet and ratchet 33 structure and the tightening band 31 achieves double fixation of the steel bar 12, preventing the steel bar 12 from loosening or falling off during the feeding process.

[0035] Several placement plates 32 are fixed between the two support legs 41. Limiting blocks 38 are fixed on the placement plates 32. Placement slots are opened above the limiting blocks 38. Moving holes 39 are opened on the limiting blocks 38. A tightening band 31 is fixed on the limiting blocks 38. The end of the tightening band 31 passes through the moving hole 39 and is fixed to the rotating cylinder 35. A spring telescopic rod 40 is provided inside the limiting block 38. A support block 29 is fixed to the end of the spring telescopic rod 40. After the steel bar 12 is placed in the placement slot of the limiting block 38, the tightening band 31 tightens under the drive of the rotating cylinder 35, clamping the steel bar 12. The spring telescopic rod 40 pushes the support block 29 to press against the steel bar 12, providing elastic compensation. Pressing the press-type cylindrical lock 34 can make the ratchet 33 disengage from the ratchet groove, realizing the rapid release of the tightening band 31. The tightening motor 30 realizes the automatic tensioning and release of the tightening band 31, reducing manual intervention and improving production efficiency.

[0036] Working principle:

[0037] The output shaft of the conveyor motor 11 is connected to the conveyor belt 5 via a pulley pair, thereby driving the conveyor belt 5 to rotate. The reinforcing bar 12 is placed on the conveyor belt 5. As the conveyor belt 5 moves, the reinforcing bar 12 is conveyed to the end position of the mounting frame 4. The reinforcing bar 12 falls onto two guide blocks 20, which guide the reinforcing bar 12 into the inside of the sleeve 19, thereby moving the reinforcing bar 12 into the conveying hole of the rotating roller 13. The rotary motor 15 drives the limiting shaft 17 to rotate via its output shaft. The limiting shaft 17 drives the rotating roller 13 to rotate, switching the position of the conveying hole. The conveying holes of the rotating roller 13 are filled with steel bars 12. The electric push rod 18 retracts, driving the fixed plate 16 to move. The fixed plate 16 drives several extrusion rods 14 to move, extruding the extrusion rods 14 out of the sleeve 19. When the moving motor 22 drives the drive shaft 27 to rotate, since the drive shaft 27 and the driven shaft 23 are connected by a bevel gear pair 24, the bevel gear pair 24 achieves synchronous rotation of the drive shaft 27 and the driven shaft 23 at a 90° angle, so that the driven shaft 23 also rotates synchronously. A conveying wheel 26 is fixed on the drive shaft 27, and the driven shaft 23 is... A second conveyor wheel 28 is fixedly positioned, and both the first conveyor wheel 26 and the second conveyor wheel 28 are located on the surface of the corresponding reinforcing bar 12. As the drive shaft 27 and the driven shaft 23 rotate, the first conveyor wheel 26 and the second conveyor wheel 28 generate friction with the surface of the reinforcing bar 12, pushing the reinforcing bar 12 towards the reserved hole 6 of the concrete pipe 1. At the same time, during the conveying process, the through hole of the mounting plate 2 provides a guide channel for the reinforcing bar 12, limiting the lateral movement range of the reinforcing bar 12 and ensuring that the reinforcing bar 12 can accurately enter the placement groove of the limiting block 38 along the preset path. Inside, the tightening motor 30 drives the rotating cylinder 35 to rotate, and the tightening band 31 is wrapped around the rotating cylinder 35. The ratchet 33 and the ratchet groove cooperate to achieve one-way locking, preventing the support leg 41 from moving in the opposite direction. The tightening band 31 is tightened under the drive of the rotating cylinder 35, clamping the steel bar 12. Then, the steel bar 12 and the limiting component are moved to the reserved hole 6 of the concrete pipe 1 to prevent the steel bar 12 from deviating from the target position due to bending or external force during the feeding process. The limiting is achieved directly by using the through hole of the mounting plate 2, which reduces manual intervention and improves production efficiency.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended embodiments and their equivalents.

Claims

1. A prestressed concrete pipe prestressing tensioning device, comprising a fixed frame (3), a rotating assembly disposed above the fixed frame (3), a concrete pipe (1) disposed above the rotating assembly, and a feeding assembly disposed on the side of the fixed frame (3), characterized in that: The feeding assembly includes a mounting frame (4), a conveyor belt (5) is provided above the mounting frame (4), a conveyor motor (11) is provided at the end of the mounting frame (4), the output shaft of the conveyor motor (11) is connected to the conveyor belt (5) through a pulley pair, a sleeve (19) is fixed on the side of the mounting frame (4), two guide blocks (20) are provided above the sleeve (19), a rotating roller (13) is rotatably provided inside the sleeve (19), a plurality of conveying holes are provided on the rotating roller (13), a limit hole is provided at one end of the rotating roller (13), and the sleeve (19) is fixed on the side of the mounting frame (4). An electric push rod (18) is fixed below the 9), and a fixed plate (16) is fixed at the end of the electric push rod (18). A rotary motor (15) is fixed on one side of the fixed plate (16), and a limit shaft (17) is fixed on the output shaft of the rotary motor (15). The limit shaft (17) is located on the other side of the fixed plate (16), and the limit shaft (17) is slidably disposed inside the limit hole. Several extrusion rods (14) are fixed on the other side of the fixed plate (16). The extrusion rods (14) are shorter than the limit shaft (17). Limiting components are provided at both ends of the fixed frame (3).

2. The prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 1, characterized in that: The concrete pipe (1) has several reserved holes (6), and the other end of the rotating roller (13) extends out of the sleeve (19).

3. The prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 2, characterized in that: The feeding assembly also includes a mounting frame (21) and two moving motors (22). The mounting frame (21) is fixed to the end of the mounting frame (4). Inside the mounting frame (21) are four connecting plates one (25) and four connecting plates two. The connecting plates one (25) and the connecting plates two are perpendicular to each other. A drive shaft (27) is rotatably mounted on two adjacent connecting plates one (25). One end of the drive shaft (27) extends through the mounting frame (21). A driven shaft (23) is rotatably mounted on two adjacent connecting plates two. The driven shaft (23) and the drive shaft (27) are connected by a bevel gear pair (24). The moving motor (22) is fixed on the mounting frame (21). The output shaft of the moving motor (22) is connected to the drive shaft (27) through a coupling. A conveying wheel two (28) is fixed on the driven shaft (23). A conveying wheel one (26) is fixed on the drive shaft (27). The conveying wheel one (26) and the conveying wheel two (28) are both located at the corresponding limiting holes.

4. The prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 1, characterized in that: The rotating assembly includes two base plates (8) and two rotating motors (10). The two base plates (8) are fixed inside the fixed frame (3). A rotating frame (7) is fixed above the base plates (8). Support wheels (9) are fixed at both ends of the rotating frame (7). The rotating motors (10) are fixed above the base plates (8). The rotating motors (10) drive the support wheels (9) to rotate through a gear pair.

5. The prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 1, characterized in that: The limiting component includes two mounting plates (2), which are fixed to both ends of the mounting frame (21) respectively, and through holes are provided on the top of the mounting plates (2).

6. The prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 5, characterized in that: The limiting component also includes two mounting posts (36), with several support legs (41) fixed to the ends of the mounting posts (36). The support legs (41) are arranged in a cross shape, and each of the support legs (41) has a movable wheel (37) rotatably mounted at its end. Both support legs (41) have ratchet grooves inside, and the same rotating cylinder (35) is rotatably mounted inside the two support legs (41). A push-type cylindrical lock (34) is mounted inside the rotating cylinder (35), and a ratchet tooth (33) is mounted at the end of the lock core of the push-type cylindrical lock (34). A tightening motor (30) is fixed on the support leg (41), and the output shaft of the tightening motor (30) is fixedly connected to the rotating cylinder (35).

7. A prestressed tensioning device for prestressed reinforced concrete pipe reinforcement according to claim 6, characterized in that: Several placement plates (32) are fixed between the support legs (41). Limiting blocks (38) are fixed on the placement plates (32). Placement slots are provided above the limiting blocks (38). Moving holes (39) are provided on the limiting blocks (38). Tightening straps (31) are fixed on the limiting blocks (38). The end of the tightening straps (31) passes through the moving holes (39) and the end of the tightening straps (31) is fixed on the rotating cylinder (35). A spring telescopic rod (40) is provided inside the limiting blocks (38). A support block (29) is fixed at the end of the spring telescopic rod (40).

Images