A kind of hoisting equipment for prefabricated building

Abstract

The present invention belongs to the field of hoisting technology, and in particular relates to a hoisting device for an assembled building, which includes a travel wheel, legs, a crossbeam, a motor, and a bottom support. The crossbeam is a telescopic structure, and two legs are swingably mounted on each end of the crossbeam, and the two legs are arranged in an "eight" shape. A motor capable of driving the four legs to swing is fixedly mounted on the crossbeam. A travel wheel is mounted on the lower end of each leg. Two mounting sleeves are slidably mounted on the crossbeam, and the mounting sleeves have hooks. In the present invention, the lifting and lowering of the crossbeam can be controlled by controlling the swinging of the four legs. Two mounting sleeves are mounted on the crossbeam, and wall panels are hung on the two mounting sleeves. The lifting and lowering of the crossbeam can control the lifting and lowering of the wall panels. In the present invention, the spacing between the two hooks can be controlled by controlling the movement of the two mounting sleeves, and the wall panels can be adapted to different sizes and lengths by adjusting the movement of the two mounting sleeves.

Description

Technical Field

[0001] The present invention belongs to the technical field of hoisting, and in particular relates to hoisting equipment on a prefabricated building. Background Art

[0002] Prefabricated construction is currently a popular construction method and is also the direction of future development.

[0003] During the construction of prefabricated buildings, wall panels are often lifted to the construction floor by cranes. During installation, the crane needs to be used for a long time to adjust the sleeves on the formwork to align with the steel bars on the floor, which is an inefficient operation.

[0004] If lifting equipment with lifting capabilities is installed on the upper floor, the wall panels can be lifted to the floor by a crane and then transferred to the lifting equipment on the upper floor; the subsequent alignment and connection process of the wall panels and the floor can be completed using the lifting equipment on the upper floor, which can greatly improve the efficiency of wall panel lifting.

[0005] As a lifting equipment upstairs, through analysis it can be concluded that it should have the following functions in order to achieve the goal of improving efficiency flexibly and efficiently.

[0006] First, the wall panels can be moved flexibly.

[0007] Second, the wall panels can be moved.

[0008] Third, it can be suitable for wall panels of different sizes and lengths.

[0009] Fourth, in addition to the ability to hoist the interior wall panels, it should also have the ability to hoist and install the exterior wall panels.

[0010] Fifth, it can be moved flexibly on the floor where wall panels or steel bars passing through the floor have been installed.

[0011] Sixth, it can be folded into a smaller volume to achieve transfer between floors.

[0012] Seventh, while achieving the above functions, the structure should be as simple as possible to reduce weight.

[0013] The present invention designs an assembled building upper floor hoisting device that can achieve the above-mentioned required functions. Summary of the Invention

[0014] In order to achieve the above object, the present invention adopts the following technical solutions:

[0015] A prefabricated building upper floor lifting equipment includes walking wheels, legs, a crossbeam, a motor, and a bottom support, wherein the crossbeam is a telescopic structure, and two legs are swingably mounted at both ends of the crossbeam, and the two legs are distributed in an "eight" shape; a motor capable of driving the four legs to swing is fixedly mounted on the crossbeam; a walking wheel is mounted at the lower end of each leg; two mounting sleeves are slidably mounted on the crossbeam, and the mounting sleeves have hooks.

[0016] When hoisting the exterior wall panels, two bottom supports are fixedly installed on the floor and one end of the bottom support extends outside the floor; two of the four legs extend outside the floor and are mounted on the two bottom supports; the bottom supports are equipped with limit bars that can limit the swing of the legs.

[0017] As a preferred solution, two limit bars are installed on the bottom support for sliding up and down; the two limit bars are fixedly connected to each other; a spring is installed between the limit bar and the bottom support; two transmission tooth plates are fixedly installed at both ends of the limit bar, and four transmission gears are rotatably installed on the bottom support in groups of two, and the two transmission gears in the same group are meshed with each other, and one of the transmission gears is meshed with the transmission tooth plate on the corresponding side; the two pedals are symmetrically installed on the bottom support for sliding, and the pedals have teeth, and the pedals are meshed with the other transmission gear of the two transmission gears on the same side; two transmission gears located on one side of the four transmission gears in the two groups are connected by a first rotating shaft.

[0018] As a preferred solution, the limit strip has a protrusion, and the lower end of the support leg is fixedly mounted with a limit rod, which cooperates with the protrusion on the limit strip.

[0019] As a preferred solution, the crossbeam consists of an inner beam and an outer beam, and a first tightening bolt is installed between the inner beam and the outer beam; two mounting sleeves are slidably installed on the inner beam and the outer beam respectively, and two synchronous racks are slidably installed in the crossbeam, and the two synchronous racks correspond to the two mounting sleeves one by one and are fixedly connected to each other; the gear mounting block is slidably installed in the crossbeam, and a synchronous gear is installed on the gear mounting block, and the synchronous gear is engaged with the two synchronous racks respectively, and the synchronous gear is located between the two synchronous racks; a plurality of evenly distributed limiting holes are opened on the inner beam and the outer beam, and a second tightening bolt for locking the gear mounting block is installed between the inner beam and the outer beam.

[0020] As a preferred solution, a mounting plate is fixedly installed at each end of the beam, and a first fixing ring and a second fixing ring are rotatably installed on the mounting plate, and the centers of the first fixing ring and the second fixing ring are staggered up and down; the four legs are correspondingly installed on the first fixing ring and the second fixing ring.

[0021] As a preferred solution, the first gear and the second gear are rotatably mounted on the mounting plate, and the first gear and the second gear are meshed; the first gear ring and the second gear ring are rotatably mounted in the mounting plate, and the first gear ring is meshed with the first gear; the second gear ring is meshed with the second gear; the first gear ring is fixedly connected to the first fixing ring; and the second gear ring is fixedly connected to the second fixing ring.

[0022] As a preferred solution, the two first gears on both sides are connected via a telescopic shaft that can transmit torque.

[0023] The rotating axis of one of the two first gears is the second rotating axis, a worm is fixedly mounted on the output shaft of the motor, the worm wheel and the third gear are coaxially rotated and mounted on the beam, and the worm wheel and the worm are meshed; the third gear is connected to the second rotating axis through a gear set.

[0024] As a preferred solution, the support leg is composed of a first rocker arm, a second rocker arm, a third rocker arm and a fourth rocker arm, one end of the first rocker arm is fixedly mounted on the mounting plate, one end of the second rocker arm is fixedly mounted on the corresponding fixed ring, the upper end of the third rocker arm is hingedly mounted on the other end of the first rocker arm, the upper end of the fourth rocker arm is hingedly mounted on the lower end of the second rocker arm, and the fourth rocker arm is hinged to the third rocker arm; the walking wheel is mounted on the lower end of the fourth rocker arm.

[0025] Compared with the existing technology, the advantages of the present invention are:

[0026] 1. In the present invention, the lifting of the crossbeam can be controlled by controlling the swing of the four legs. Two mounting sleeves are installed on the crossbeam, and the wall panels are hung on the two mounting sleeves. The lifting of the crossbeam can control the lifting of the wall panels.

[0027] 2. In the present invention, the distance between the two hooks can be controlled by controlling the movement of the two installation sleeves, that is, the wall panels of different sizes and lengths can be adapted by adjusting the movement of the two installation sleeves.

[0028] 3. When hoisting the exterior wall panels, in order to facilitate the installation of the legs, the four legs are controlled to be as close to the middle as possible; on the one hand, because the four legs are close to the middle, the spacing between the supports required by the four legs is relatively small, and the installation space is relatively small; on the other hand, in order to ensure that the equipment does not fall over, the present invention also specially designs a bottom support. The designed bottom support can further lock the legs while ensuring the smooth installation of the equipment.

[0029] 4. In the present invention, on the one hand, the length of the crossbeam can be adjusted, and on the other hand, the spacing between the legs can also be adjusted. In this way, when the equipment passes through the steel bars extending from the floor, the legs and the crossbeam can be flexibly adjusted so that the equipment can pass through the steel bars smoothly.

[0030] 5. When the floor is being transferred, the present invention controls the crossbeam to shorten and the four legs to move closer, so that the device is folded, so as to facilitate access to higher floors via stairs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the overall appearance of the components.

[0032] Figure 2 This is a schematic diagram of the coordination between the limit rod and the bottom support.

[0033] Figure 3 It is a schematic diagram of the bottom support structure.

[0034] Figure 4 It is a schematic diagram of the limit bar structure.

[0035] Figure 5 This is a schematic diagram of the beam installation.

[0036] Figure 6 This is a schematic diagram of the motor installation.

[0037] Figure 7 This is a schematic diagram of the outer beam installation.

[0038] Figure 8 It is a schematic diagram of the beam structure.

[0039] Figure 9 This is a schematic diagram of the cooperation between the first gear and the second gear.

[0040] Figure 10 This is a schematic diagram of the worm installation.

[0041] Figure 11 This is a schematic diagram of installing the sliding sleeve.

[0042] Figure 12 This is a diagram of the worm gear installation.

[0043] Figure 13 This is a schematic diagram of the installation of the first fixing ring and the second fixing ring.

[0044] Figure 14 It is a schematic diagram of the structure of the first fixing ring and the second fixing ring.

[0045] Figure 15 It is a schematic diagram of the leg structure.

[0046] Figure 16 This is a schematic diagram of exterior wall panel hoisting.

[0047] Reference numerals in the figure: 1. bottom support; 2. traveling wheel; 3. outrigger; 4. crossbeam; 5. motor; 6. limit rod; 7. limit bar; 8. pedal; 9. first rotating shaft; 10. transmission gear plate; 11. transmission gear; 12. spring; 13. mounting sleeve; 14. hook; 15. mounting plate; 16. outer beam; 17. inner beam; 18. telescopic rotating shaft; 19. first tightening bolt; 20. gear mounting block; 21. synchronous gear; 22. Second tightening bolt; 23. Synchronous rack; 24. Limiting hole; 25. First gear; 26. Second gear; 27. Worm; 28. Worm wheel; 29. Third gear; 30. Second rotating shaft; 31. Gear set; 32. First fixing ring; 33. First rocker arm; 34. Second rocker arm; 35. First ring gear; 36. Second fixing ring; 37. Second ring gear; 38. Third rocker arm; 39. Fourth rocker arm; 40. Exterior wall panel. DETAILED DESCRIPTION

[0048] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following embodiments or drawings are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0049] A kind of hoisting equipment for prefabricated building, such as Figure 1 As shown, it includes walking wheels 2, legs 3, beams 4, motors 5, and bottom supports 1, wherein Figure 8 、 11 As shown, the crossbeam 4 is a telescopic structure composed of an inner beam 17 and an outer beam 16, and a first tightening bolt 19 is installed between the inner beam 17 and the outer beam 16; Figure 5 、 6 As shown in FIG. 7 , a mounting plate 15 is fixedly mounted at each end of the beam 4, and four legs 3 are mounted on the two mounting plates 15; Figure 8 、 11 As shown, the two mounting sleeves 13 are respectively slidably mounted on the inner beam 17 and the outer beam 16, and the mounting sleeves 13 are provided with a hook 14; the two synchronization racks 23 are slidably mounted in the crossbeam 4, and the two synchronization racks 23 correspond one-to-one to the two mounting sleeves 13 and are fixedly connected to each other; the gear mounting block 20 is slidably mounted in the crossbeam 4, and a synchronization gear 21 is mounted on the gear mounting block 20, and the synchronization gear 21 is respectively engaged with the two synchronization racks 23, and the synchronization gear 21 is located between the two synchronization racks 23; a plurality of evenly distributed limiting holes 24 are opened on the inner beam 17 and the outer beam 16, and a second tightening bolt 22 for locking the gear mounting block 20 is installed between the inner beam 17 and the outer beam 16.

[0050] In the present invention, the spacing between the two hooks 14 can be controlled by controlling the movement of the two mounting sleeves 13. This allows the adjustment of the movement of the two mounting sleeves 13 to accommodate wall panels of varying sizes and lengths. The function of the synchronization rack 23 and the synchronization rack 23 is to ensure that the center of the two hooks 14 remains unchanged during the adjustment process.

[0051] like Figure 13 、 14 As shown, the first fixing ring 32 and the second fixing ring 36 are rotatably mounted on the mounting plate 15, and the centers of the first fixing ring 32 and the second fixing ring 36 are staggered up and down; Figure 15 As shown, the support leg 3 is composed of a first rocker arm 33, a second rocker arm 34, a third rocker arm 38 and a fourth rocker arm 39. One end of the first rocker arm 33 is fixedly mounted on the mounting plate 15, one end of the second rocker arm 34 is fixedly mounted on the corresponding fixing ring, the upper end of the third rocker arm 38 is hingedly mounted on the other end of the first rocker arm 33, the upper end of the fourth rocker arm 39 is hingedly mounted on the lower end of the second rocker arm 34, and the fourth rocker arm 39 is hinged to the third rocker arm 38; the lower end of the fourth rocker arm 39 is mounted with a walking wheel 2, and the walking wheel 2 is a universal wheel.

[0052] When the first fixing ring 32 and the second fixing ring 36 are driven to rotate, the first fixing ring 32 and the second fixing ring 36 will drive the corresponding second swing rod 34 to swing, because the first swing rod 33 is vertically fixed on the mounting plate 15 and passes through the center of the corresponding fixing ring after extending upward; in the present invention, the first swing rod 33, the second swing rod 34, the third swing rod 38 and the fourth swing rod 39 form a parallelogram structure, and because the first swing rod 33 is vertically fixed, when the second swing rod 34 is driven to swing, the fourth swing rod 39 is always in a vertical state, and the walking wheel 2 is always perpendicular to the floor.

[0053] like Figure 9 As shown, the mounting plate 15 is rotatably mounted with a first gear 25 and a second gear 26, and the first gear 25 and the second gear 26 are meshed; the first gear ring 35 and the second gear ring 37 are rotatably mounted in the mounting plate 15, the first gear ring 35 is meshed with the first gear 25; the second gear ring 37 is meshed with the second gear 26; the first gear ring 35 is fixedly connected to the first fixing ring 32; the second gear ring 37 is fixedly connected to the second fixing ring 36; the two first gears 25 on both sides are connected by a retractable rotating shaft 18 that can transmit torque; the rotating shaft of one of the two first gears 25 is the second rotating shaft 30, as shown in FIG. Figure 10 、 12 As shown, the motor 5 is fixedly mounted on the beam 4, a worm 27 is fixedly mounted on the output shaft of the motor 5, a worm wheel 28 and a third gear 29 are coaxially mounted on the beam 4, and the worm wheel 28 and the worm 27 are meshed; the third gear 29 is connected to the second rotating shaft 30 through a gear set 31.

[0054] When the motor 5 is working, it can drive the worm 27 to rotate. The rotation of the worm 27 drives the turbine to rotate. The rotation of the turbine drives the third gear 29 to rotate. The rotation of the third gear 29 drives the second rotating shaft 30 to rotate through the gear set 31. The rotation of the second rotating shaft 30 drives the corresponding first gear 25 to rotate. The rotation of the first gear 25 drives the second gear 26 on the same side to rotate. At the same time, the rotation of the first gear 25 drives the first gear 25 on the other side to rotate through the transmission shaft. The rotation of the first gear 25 drives the first ring gear 35 to rotate. The rotation of the first ring gear 35 drives the first fixing ring 32 to rotate. The rotation of the second gear 26 drives the second ring gear 37 to rotate. The rotation of the second ring gear 37 drives the second fixing ring 36 to rotate. Since the first gear 25 and the second gear 26 are directly meshed, the rotation directions of the first fixing ring 32 and the second fixing ring 36 are opposite.

[0055] The present invention can lock the support leg 3 after it swings through the self-locking function of the worm 27 and the worm wheel 28.

[0056] like Figure 1 As shown, when hoisting the exterior wall panel 40, two bottom supports 1 are fixedly installed on the floor, and one end of the bottom support 1 extends outside the floor; two of the four legs 3 extend outside the floor and are mounted on the two bottom supports 1; Figure 3 、 4 As shown, two limit bars 7 are installed on the bottom support 1 for sliding up and down; the two limit bars 7 are fixedly connected to each other; a spring 12 is installed between the limit bar 7 and the bottom support 1; two transmission tooth plates 10 are fixedly installed at both ends of the limit bar 7, and four transmission gears 11 are rotatably installed on the bottom support 1 in groups of two, and the two transmission gears 11 in the same group are meshed with each other, and one of the transmission gears 11 is meshed with the transmission tooth plate 10 on the corresponding side; the two pedals 8 are symmetrically slidably installed on the bottom support 1, and the pedals 8 have teeth, and the pedals 8 are meshed with the other transmission gear 11 of the two transmission gears 11 on the same side; the two transmission gears 11 on one side of the four transmission gears 11 in the two groups are connected by a first rotating shaft 9; as shown Figure 2 As shown, the limiting strip 7 has a protrusion, and the lower end of the supporting leg 3 is fixedly mounted with a limiting rod 6 , which cooperates with the protrusion on the limiting strip 7 .

[0057] When the pedal 8 is pressed down, the pedal 8 will drive the two transmission gear plates 10 to move downward through the four transmission gears 11, and the transmission gear plates 10 will drive the limit bar 7 to move downward, releasing the limit on the support leg 3; the function of the spring 12 is to reset the limit bar 7 upward; when the limit bar 7 and the limit rod 6 cooperate, the limit bar 7 can further lock the swing of the support leg 3.

[0058] like Figure 16When the support legs 3 are in a state of being moved to the right and left, the four support legs 3 are moved to the left and right positions, so that the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs 3 can be easily moved to the left and right positions, and the support legs

[0059] In the present invention, on the one hand, the length of the crossbeam 4 can be adjusted, and on the other hand, the spacing between the legs 3 can also be adjusted. In this way, when the equipment passes through the steel bars extending from the floor, the legs 3 and the crossbeam 4 can be flexibly adjusted so that the equipment can pass through the steel bars smoothly.

[0060] When moving from one floor to another, the control beam 4 is shortened and the four legs 3 are brought together, allowing the device to fold, facilitating access to higher floors via stairs. While the control beam 4 is shortened, the second tightening bolt 22 locking the gear mounting block 20 can be loosened to prevent the synchronous gear 21 and the synchronous rack 23 from affecting the extension and retraction of the beam 4. After the control beam 4 is opened, the gear mounting block 20 can be locked again with the second tightening bolt 22.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification or equivalent change made to the above embodiment based on the technical essence of the present invention shall fall within the scope of protection of the present invention.

[0062] Implementation method: When the equipment designed by the present invention is used, the motor 5 is controlled to work during hoisting. When the motor 5 is working, it can drive the worm 27 to rotate. The rotation of the worm 27 drives the turbine to rotate. The rotation of the turbine drives the third gear 29 to rotate. The rotation of the third gear 29 drives the second shaft 30 to rotate through the gear set 31. The rotation of the second shaft 30 drives the corresponding first gear 25 to rotate. The rotation of the first gear 25 drives the second gear 26 on the same side to rotate. At the same time, the rotation of the first gear 25 drives the first gear 25 on the other side to rotate through the transmission shaft. The rotation of the first gear 25 drives The first ring gear 35 rotates, and the rotation of the first ring gear 35 drives the first fixed ring 32 to rotate. The rotation of the second gear 26 drives the second ring gear 37 to rotate. The rotation of the second ring gear 37 drives the second fixed ring 36 to rotate. When the first fixed ring 32 and the second fixed ring 36 are driven to rotate, the first fixed ring 32 and the second fixed ring 36 will drive the support legs 3 to swing. By controlling the swing of the four support legs 3, the lifting and lowering of the beam 4 can be controlled. Two mounting sleeves 13 are installed on the beam 4, and the wall panels are hung on the two mounting sleeves 13. The lifting and lowering of the beam 4 can control the lifting and lowering of the wall panels.

[0063] When the support legs 3 are in the upright position, the four support legs 3 are moved closer to the center as much as possible. On the one hand, because the four support legs 3 are moved closer to the center, the spacing between the supports required by the four support legs 3 is relatively small. On the other hand, in order to ensure that the equipment does not fall over, the present invention also specially designs a bottom support 1, and two bottom supports 1 are fixedly installed on the floor, and one end of the bottom support 1 extends outward from the floor. Two of the four support legs 3 extend outward from the floor and are mounted on the two bottom supports 1. When installing the equipment, the walking wheels 2 are clamped on the bottom supports 1 so that the walking wheels 2 slide with the bottom supports 1, and then the equipment is pushed outward. When pushing the equipment, it is necessary to control the limit bar 7 to move downward to release the limit on the walking wheels 2. When the equipment is moved to the appropriate position and the adjustment of the support legs 3 is completed, the limit bar 7 is moved upward, and the swing of the four support legs 3 is locked by the cooperation of the limit bar 7 and the limit rod 6.

Claims

1. A hoisting device for an assembled building, characterized by: It includes running wheels, legs, a crossbeam, a motor, and a bottom support. The crossbeam is a telescopic structure, with two legs swingingly mounted at both ends of the crossbeam, and the two legs are arranged in an "eight" shape. A motor capable of driving the four legs to swing is fixedly mounted on the crossbeam. A running wheel is mounted at the lower end of each leg. Two mounting sleeves are slidably mounted on the crossbeam, and each mounting sleeve has a hook. When hoisting the exterior wall panels, two bottom supports are fixedly installed on the floor, and one end of the bottom support extends outside the floor; two of the four legs extend outside the floor and are mounted on the two bottom supports; the bottom supports are equipped with limit bars that can limit the swing of the legs; A mounting plate is fixedly mounted on each end of the crossbeam, and a first fixing ring and a second fixing ring are rotatably mounted on the mounting plates, respectively. The centers of the first fixing ring and the second fixing ring are staggered up and down; and four legs are correspondingly mounted on the first fixing ring and the second fixing ring. The mounting plate is rotatably mounted with a first gear and a second gear, the first gear and the second gear being meshed; the first gear ring and the second gear ring are rotatably mounted within the mounting plate, the first gear ring being meshed with the first gear; the second gear ring being meshed with the second gear; the first gear ring being fixedly connected to the first fixing ring; and the second gear ring being fixedly connected to the second fixing ring; The two first gears on both sides are connected by a telescopic shaft capable of transmitting torque; The support leg is composed of a first swing link, a second swing link, a third swing link and a fourth swing link, one end of the first swing link is fixedly mounted on the mounting plate, one end of the second swing link is fixedly mounted on the corresponding fixing ring, the upper end of the third swing link is hingedly mounted on the other end of the first swing link, the upper end of the fourth swing link is hingedly mounted on the lower end of the second swing link, and the fourth swing link is hinged to the third swing link; The traveling wheel is mounted on the lower end of the fourth swing rod; The rotating axis of one of the two first gears is the second rotating axis, a worm is fixedly mounted on the output shaft of the motor, the worm wheel and the third gear are coaxially rotated and mounted on the beam, and the worm wheel and the worm are meshed; the third gear is connected to the second rotating axis through a gear set.

2. The hoisting equipment for an assembled building according to claim 1, characterized in that: Two limit bars are installed on the bottom support for sliding up and down; the two limit bars are fixedly connected to each other; a spring is installed between the limit bar and the bottom support; two transmission tooth plates are fixedly installed on both ends of the limit bar, and four transmission gears are rotatably installed on the bottom support in groups of two, and the two transmission gears in the same group are meshed with each other, and one of the transmission gears is meshed with the transmission tooth plate on the corresponding side; two pedals are symmetrically installed on the bottom support for sliding, and the pedals have teeth, and the pedals are meshed with the other transmission gear of the two transmission gears on the same side; two transmission gears located on one side of the four transmission gears in the two groups are connected by a first rotating shaft.

3. The hoisting equipment for an assembled building according to claim 2, characterized in that: The limit strip is provided with a protrusion, and the lower end of the support leg is fixedly mounted with a limit rod, which cooperates with the protrusion on the limit strip.

4. The hoisting equipment for an assembled building according to claim 1, characterized in that: The crossbeam is composed of an inner beam and an outer beam, and a first tightening bolt is installed between the inner beam and the outer beam; two mounting sleeves are slidably installed on the inner beam and the outer beam respectively, and two synchronous racks are slidably installed in the crossbeam, and the two synchronous racks correspond to the two mounting sleeves one by one and are fixedly connected to each other; the gear mounting block is slidably installed in the crossbeam, and a synchronous gear is installed on the gear mounting block, and the synchronous gear is engaged with the two synchronous racks respectively, and the synchronous gear is located between the two synchronous racks; a plurality of evenly distributed limiting holes are opened on the inner beam and the outer beam, and a second tightening bolt for locking the gear mounting block is installed between the inner beam and the outer beam.

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