Integral hoisting construction device and method for upright quadrangular pyramid spherical grid structure

By designing an integral lifting construction device for forward-placement of quadrangular cone spherical mesh, the problem of poor lifting stability of the grid frame in the prior art is solved, and the accurate alignment and stability of the grid frame during the lifting process is achieved.

CN120191830APending Publication Date: 2025-06-24THE FIRST COMPARY OF CHINA EIGHTH ENG BUREAU LTD
View PDF 0 Cites 0 Cited by

Patent Information

Application Number
CN202510401146.5
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-04-01
Publication Date
2025-06-24

AI Technical Summary

Technical Problem

In the prior art, the quadrangular cone spherical mesh structure has poor stability during the lifting process and is prone to shaking, resulting in the inability to accurately align the design position.

Method used

An integral lifting construction device is designed, including a central block, a lifting arm, a telescopic groove, a connecting block, a connecting rod, a sliding block and a fixing component. By adjusting the pull rod, pushing the sliding block and tumbling the limit insert, the flexible adjustment and fixing of the telescopic lifting arm is achieved, ensuring the stability of the mesh frame during the lifting process.

Benefits of technology

Through this device, the shaking of the forwardly placed quadrangular cone spherical mesh can be effectively prevented from being shaken during lifting, ensuring that it can be accurately aligned with the design position, and improving the stability and accuracy of the lifting.

✦ Generated by Eureka AI based on patent content.

Smart Images

  • Figure CN120191830A_ABST
    Figure CN120191830A_ABST
Patent Text Reader

Abstract

The invention relates to the technical field of overall hoisting construction devices for upright quadrangular pyramid spherical grid structures, in particular to an overall hoisting construction device and method for upright quadrangular pyramid spherical grid structures. The overall hoisting construction device comprises a center block, hoisting arms are fixedly arranged on the periphery of the center block, and first telescopic grooves are formed in the middles of the hoisting arms; a telescopic hoisting arm is slidably connected into the first telescopic groove, a connecting block is fixedly connected to the bottom of the rear end of the telescopic hoisting arm, connecting rods are connected to the two ends of the connecting block and penetrate out of through grooves formed in the two sides of the bottom of the telescopic hoisting arm, and sliding blocks are connected to the top ends of the connecting rods; the overall hoisting construction device and method for the upright quadrangular pyramid spherical grid structure have the beneficial effects that firstly, the center block is connected with a crane through the hoisting hook at the top of the center block, and then a pull rod is pulled; and the pull rod pulls the connecting plate and a fixed insertion rod connected with the middle of the bottom of the connecting plate to be separated from first fixing holes formed in the tops of the connecting rod and the telescopic hoisting arm.
Need to check novelty before this filing date? Find Prior Art

Description

Technical Field

[0001] The present invention relates to the technical field of integral hoisting construction devices for a square pyramid spherical grid structure placed upright, and specifically to an integral hoisting construction device and method for a square pyramid spherical grid structure placed upright. Background Technique

[0002] A square pyramid spherical grid structure placed upright is a grid structure composed of inverted square pyramid basic units. The four sides of the cone bottom are the upper chord bars of the grid, the cone edges are the web members, and the connection of the cone tops is the lower chord bar, which is a common form of spatial grid structure.

[0003] In the prior art, for a square pyramid spherical grid structure placed upright, usually after the grid is assembled on the ground, it is usually hoisted to the set position by a high-altitude crane bundling steel wires and bundling the steel wires at the central position of the square pyramid spherical grid structure placed upright.

[0004] However, for the above hoisting method, only the position of the square pyramid spherical grid structure placed upright is hoisted, and its stability is not good. When hoisting the square pyramid spherical grid structure placed upright, it is very easy to shake during hoisting, resulting in misalignment when reaching the designed position. Therefore, we provide an integral hoisting construction device and method for a square pyramid spherical grid structure placed upright to solve the above problems. Summary of the Invention

[0005] The purpose of the present invention is to provide an integral hoisting construction device and method for a square pyramid spherical grid structure placed upright to solve the problems raised in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solutions: a central block, with hoisting arms fixedly arranged around the central block. A first telescopic groove is opened in the middle of the hoisting arm, and a telescopic hoisting arm is slidably connected in the first telescopic groove. A connecting block is fixedly connected to the bottom of the rear end of the telescopic hoisting arm. Both ends of the connecting block are connected to connecting rods. The connecting rods pass through through grooves opened on both sides of the bottom of the telescopic hoisting arm. The top ends of the connecting rods are connected to sliding blocks. A fixing component is arranged in the middle of the top end of the sliding block. The sliding block is located at the top of the telescopic hoisting arm; and multiple groups of first fixing holes are opened simultaneously in the middle of the bottom of the fixing component and on the surface of the first telescopic groove for the connecting rods.

[0007] Preferably, a support column is fixedly arranged at the bottom of the central block, and hinge shafts are arranged around the bottom end of the support column, and support rods are hinged on the hinge shafts.

[0008] Preferably, a telescopic groove is opened in the middle of the support rod, and a telescopic support rod is inserted in the telescopic groove. Multiple groups of second fixing holes are opened simultaneously on the front end of the support rod and on the telescopic support rod. Fixing bolts can be inserted into the second fixing holes to fix the telescopic support rod in a telescopic state.

[0009] Preferably, one end of the telescopic support rod is inserted into a telescopic groove provided in the support rod, and the other end is connected to a connecting block connected to the bottom of the rear end of the telescopic lifting arm through a hinge shaft.

[0010] Preferably, a cavity is opened in the middle of the fixing component, and multiple groups of first springs are arranged around the bottom of the fixing component, the bottom of the first spring is connected to the top surface of the connecting rod, the top of the first spring is connected to the connecting plate, and a fixing rod is arranged in the middle of the top of the connecting plate, and the fixing rod is parallel to the first fixing hole opened in the top of the connecting rod.

[0011] Preferably, a pull rod is connected to the middle of the top of the connecting plate, and the pull rod extends from the top of the fixing assembly. Pulling the pull rod can cause the pull rod to drive the connecting plate and the first spring at the bottom of the connecting plate to rise and fall.

[0012] Preferably, the top end of the fixing component is provided with a second telescopic groove on both sides of the pull rod, a second spring is arranged in the second telescopic groove, the rear end of the second spring is connected to the inner side of the outer side of the second telescopic groove, and the inner side of the second telescopic groove is connected to the limiting plug.

[0013] Preferably, limit slots are provided on both sides of the upper and lower ends of the pull rod, and the limit plug can be ejected into the limit slot by the elastic force of the second spring. The rear end top of the limit plug is connected to the toggle block, and the toggle block extends from the second telescopic slot.

[0014] Preferably, a hook is provided in the middle of the top of the center block, which is used to connect to the crane, and connecting rings are provided in the middle of the bottom of the support column, the middle of the bottom of the connecting block and the bottom of the front end of the telescopic lifting arm, which are used to connect to the lifting wire rope.

[0015] A method for using an upright tetrahedral spherical grid structure integral hoisting construction device comprises the following steps:

[0016] Step 1: Adjust, pull the pull rod so that the pull rod pulls the connecting plate and the fixed plug rod connected to the middle part of the bottom of the connecting plate to disengage from the first fixing hole opened in the connecting rod and the top of the telescopic lifting arm, cancel the fixation of the telescopic lifting arm, and align the second spring with the limiting slots opened on both sides of the bottom end of the pull rod. At this time, the second spring bounces the limiting plug block into the limiting slot through the tension force to fix the contraction of the pull rod, and then pushes the sliding block according to the size diameter of the upright tetrahedral spherical grid, so that the sliding block drives the connecting block and the telescopic lifting arm connected to the top of the connecting block to extend outward through the connecting rods on both sides. When the front end of the telescopic lifting arm reaches the outer edge of the upright tetrahedral spherical grid, stop pushing the connecting rod;

[0017] Step 2: Fixing. Push the limit plug connected to the top of the rear end of the second spring outward, so that the limit plug squeezes the second spring and contracts into the second telescopic groove, canceling the limit on the pull rod. At this time, the first springs arranged around the bottom of the connecting plate pull the connecting plate to contract through the contraction force, and the fixed insertion rod in the middle of the bottom of the connecting plate is inserted into the first fixing hole opened at the top of the connecting rod and the first telescopic groove, realizing the telescopic fixation of the telescopic lifting arm. The limit plug is inserted into the limit slots opened on both sides of the top end of the pull rod through the tension of the second spring to limit the pull rod again.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The present invention provides an integral hoisting construction device and method for a regular square pyramid spherical grid structure. First, connect the central block to the crane through the hook on the top of the central block. Then, pull the pull rod, so that the pull rod pulls the connecting plate and the fixed insertion rod connected to the middle of the bottom of the connecting plate out of the first fixing hole opened at the top of the connecting rod and the telescopic lifting arm, canceling the fixation of the telescopic lifting arm, and aligning the second spring with the limit slots opened on both sides of the bottom end of the pull rod. At this time, the second spring pops the limit plug into the limit slots through the tension, fixing the contraction of the pull rod. Then, push the sliding block according to the diameter of the regular square pyramid spherical grid, so that the sliding block drives the connecting block and the telescopic lifting arm connected to the top of the connecting block to extend outward through the connecting rods on both sides. When the front end of the telescopic lifting arm reaches the outer edge of the regular square pyramid spherical grid, stop pushing the connecting rod. Then, push the limit plug connected to the top of the rear end of the second spring outward, so that the limit plug squeezes the second spring and contracts into the second telescopic groove, canceling the limit on the pull rod. At this time, the first springs arranged around the bottom of the connecting plate pull the connecting plate to contract through the contraction force, and the fixed insertion rod in the middle of the bottom of the connecting plate is inserted into the first fixing hole opened at the top of the connecting rod and the first telescopic groove, realizing the telescopic fixation of the telescopic lifting arm. The limit plug is inserted into the limit slots opened on both sides of the top end of the pull rod through the tension of the second spring to limit the pull rod again. While the telescopic lifting arm is telescoping, the telescopic support rod hinged to the rear end of the connecting block through the hinge shaft synchronously telescopes in the telescopic groove opened in the middle of the support rod. When the telescopic adjustment of the telescopic lifting arm is completed, insert the fixing bolt into the second fixing hole where the front end of the support rod coincides with the telescopic support rod to fix the telescopic support rod, so that the support rod and the telescopic support rod always support the central position of the first telescopic groove and the telescopic lifting arm. At this time, the support column is located in the middle of the regular square pyramid spherical grid. Then, tie the steel wires to the connecting rings arranged at the bottom of the outer ends of the support column, the connecting block and the telescopic lifting arm respectively. The other ends of the steel wires are tied to the center of the regular square pyramid spherical grid, the four edges, and the centers of the center and the four edges of the regular square pyramid spherical grid respectively, connecting the device to multiple positions of the regular square pyramid spherical grid to prevent the regular square pyramid spherical grid from shaking during hoisting. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0021] Figure 2 for Figure 2 A schematic diagram of the enlarged structure of the structure at center A;

[0022] Figure 3 It is a schematic diagram of the top view structure of the present invention;

[0023] Figure 4 It is a schematic diagram of the cross-sectional structure of the present invention;

[0024] Figure 5 for Figure 4 A schematic diagram of the enlarged structure at B in the middle;

[0025] Figure 6 It is a schematic diagram of the cross-sectional structure of the fixing component of the present invention.

[0026] In the figure: center block 1, hook 2, support column 3, lifting arm 4, first telescopic slot 5, telescopic lifting arm 6, hinge shaft 7, support rod 8, telescopic support rod 9, connecting block 10, through slot 11, connecting rod 12, sliding block 13, fixing assembly 14, first fixing hole 15, second fixing hole 16, fixing bolt 17, pull rod 18, connecting plate 19, first spring 20, fixing plug rod 21, limiting slot 22, second telescopic slot 23, second spring 24, limiting plug block 25, toggle block 26, connecting lifting ring 27. DETAILED DESCRIPTION

[0027] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit 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.

[0028] See also Figures 1 to 6The present invention provides a technical solution: a center block 1, a lifting arm 4 is fixedly arranged around the center block 1, a first telescopic slot 5 is opened in the middle of the lifting arm 4, a telescopic lifting arm 6 is slidably connected in the first telescopic slot 5, a connecting block 10 is fixedly connected to the bottom of the rear end of the telescopic lifting arm 6, both ends of the connecting block 10 are connected to a connecting rod 12, the connecting rod 12 passes through the through slots 11 opened on both sides of the bottom of the telescopic lifting arm 6, the top of the connecting rod 12 is connected to a sliding block 13, a fixed component 14 is arranged in the middle of the top of the sliding block 13, and the sliding block 13 is located at the top of the telescopic lifting arm 6; and the connecting rod 12 is simultaneously opened in the middle of the bottom of the fixing component 14 and on the surface of the first telescopic slot 5 There are multiple groups of first fixing holes 15; a support column 3 is fixedly arranged at the bottom of the center block 1, and a hinge shaft 7 is arranged around the bottom end of the support column 3, and a support rod 8 is hinged on the hinge shaft 7; a telescopic groove is opened in the middle of the support rod 8, and a telescopic support rod 9 is inserted in the telescopic groove. A plurality of second fixing holes 16 are opened on the front end of the support rod 8 and the telescopic support rod 9 at the same time, and a fixing bolt 17 can be inserted in the second fixing hole 16 to fix the telescopic support rod 9; one end of the telescopic support rod 9 is inserted in the telescopic groove opened in the support rod 8, and the other end is connected to the connecting block 10 connected to the bottom of the rear end of the telescopic lifting arm 6 through the hinge shaft 7; a cavity is opened in the middle of the fixing component 14, and the fixing component 14 A plurality of groups of first springs 20 are arranged around the bottom, the bottom of the first spring 20 is connected to the top surface of the connecting rod 12, the top of the first spring 20 is connected to the connecting plate 19, a fixed plug rod 21 is arranged in the middle of the top of the connecting plate 19, and the fixed plug rod 21 is parallel to the first fixing hole 15 opened at the top of the connecting rod 12; a pull rod 18 is connected to the middle of the top of the connecting plate 19, and the pull rod 18 extends from the top of the fixing component 14. Pulling the pull rod 18 can make the pull rod 18 drive the connecting plate 19 and the first spring 20 at the bottom of the connecting plate 19 to rise and fall; a second telescopic groove 23 is opened on both sides of the pull rod 18 at the top of the fixing component 14, and a second spring 24 is arranged in the second telescopic groove 23. The rear end of the second spring 24 is connected to the outer inner side of the second telescopic slot 23, and the inner side of the second telescopic slot 23 is connected to the limit plug 25; the upper and lower ends of the pull rod 18 are simultaneously provided with limit slots 22, and the limit plug 25 can be ejected into the limit slot 22 by the elastic force of the second spring 24, and the rear end top of the limit plug 25 is connected to the toggle block 26, and the toggle block 26 extends out of the second telescopic slot 23; a hook 2 is provided in the middle of the top of the center block 1, and the hook 2 is used to connect with the crane, and a connecting ring 27 is provided at the middle of the bottom of the support column 3, the middle of the bottom of the connecting block 10 and the bottom of the front end of the telescopic lifting arm 6, and the connecting ring 27 is used to connect with the lifting wire rope.

[0029] In actual use, the center block 1 is first connected to the crane through the hook 2 on the top of the center block 1, and then the pull rod 18 is pulled so that the pull rod 18 pulls the connecting plate 19 and the fixed plug rod 21 connected to the middle part of the bottom of the connecting plate 19 to disengage from the first fixing hole 15 opened on the connecting rod 12 and the top of the telescopic lifting arm 6, canceling the fixation of the telescopic lifting arm 6, and aligning the second spring 24 with the limiting slots 22 opened on both sides of the bottom end of the pull rod 18. At this time, the second spring 24 uses tension to bounce the limiting plug block 25 into the limiting slot 22, fixes the contraction of the pull rod 18, and then pushes the sliding block 1 according to the size diameter of the upright tetrahedral spherical grid. 3, the sliding block 13 drives the connecting block 10 and the telescopic hanging arm 6 connected to the top of the connecting block 10 to extend outward through the connecting rods 12 connected to the two sides. When the front end of the telescopic hanging arm 6 reaches the outer edge of the upright tetrahedral spherical grid, the connecting rod 12 is stopped from being pushed. Then, the limiting plug 25 connected to the top of the rear end of the second spring 24 is pushed outward, so that the limiting plug 25 squeezes the second spring 24 and shrinks into the second telescopic groove 23, canceling the limit of the pull rod 18. At this time, the first spring 20 arranged around the bottom of the connecting plate 19 pulls the connecting plate 19 to shrink through the shrinkage force, and the middle of the bottom of the connecting plate 19 is The fixing plug rod 21 is inserted into the first fixing hole 15 opened at the top of the connecting rod 12 and the first telescopic slot 5, and the telescopic lifting arm 6 is telescopically fixed. The limiting plug block 25 is inserted into the limiting slots 22 opened on both sides of the top of the pull rod 18 through the tension of the second spring 24, and the pull rod 18 is limited again; while the telescopic lifting arm 6 is telescopic, the telescopic support rod 9 hinged by the hinge shaft 7 at the rear end of the connecting block 10 is synchronously telescoped in the telescopic slot opened in the middle of the support rod 8. When the adjustment of the telescopic lifting arm 6 is completed, the telescopic support rod 8 is fixed by inserting the fixing bolt 17 into the second fixing hole 16 that coincides with the telescopic support rod 9 at the front end of the support rod 8. 9 is telescopically fixed so that the support rod 8 and the telescopic support rod 9 always support the center position of the first telescopic slot 5 and the telescopic lifting arm 6. At this time, the support column 3 is located in the middle of the upright tetrahedral spherical grid, and then is tied to the support column 3, the connecting block 10 and the connecting ring 27 set at the bottom of the outer end of the telescopic lifting arm 6 through the steel wire rope, and the other end of the steel wire rope is tied to the center and the surrounding edges of the upright tetrahedral spherical grid and the center and the surrounding edges of the upright tetrahedral spherical grid, respectively, to connect the device to multiple positions of the upright tetrahedral spherical grid to prevent the upright tetrahedral spherical grid from shaking during lifting.

[0030] Although the above describes the illustrative specific implementation methods of the present application so that technicians in this technical field can understand the present application, the present application is not limited to the scope of the specific implementation methods. For ordinary technicians in this technical field, as long as various changes are within the spirit and scope of the present application defined and determined by the attached claims, all application creations using the concept of the present application are protected.

Claims

1. An integral hoisting construction device for a square pyramid spherical grid structure, characterized in that: include: A central block (1), a lifting arm (4) is fixedly arranged around the central block (1), a first telescopic slot (5) is provided in the middle of the lifting arm (4), a telescopic lifting arm (6) is slidably connected in the first telescopic slot (5), a connecting block (10) is fixedly connected to the bottom of the rear end of the telescopic lifting arm (6), both ends of the connecting block (10) are connected to a connecting rod (12), the connecting rod (12) passes through through slots (11) provided on both sides of the bottom of the telescopic lifting arm (6), the top of the connecting rod (12) is connected to a sliding block (13), a fixing component (14) is provided in the middle of the top of the sliding block (13), and the sliding block (13) is located at the top of the telescopic lifting arm (6); and The connecting rod (12) is provided with a plurality of first fixing holes (15) at the middle of the bottom of the fixing assembly (14) and on the surface of the first telescopic slot (5).

2. The overall hoisting construction device for an upright tetrahedral spherical grid structure according to claim 1, characterized in that: A support column (3) is fixedly arranged at the bottom of the central block (1), a hinge shaft (7) is arranged around the bottom end of the support column (3), and a support rod (8) is hingedly connected to the hinge shaft (7).

3. The overall hoisting construction device for a right-standing tetrahedral spherical grid structure according to claim 2 is characterized in that: A telescopic groove is provided in the middle of the support rod (8), in which the telescopic support rod (9) is inserted; a plurality of groups of second fixing holes (16) are provided at the front end of the support rod (8) and on the telescopic support rod (9); fixing bolts (17) can be inserted into the second fixing holes (16) to fix the telescopic support rod (9).

4. The overall hoisting construction device for a right-standing quadrangular pyramid spherical grid structure according to claim 3 is characterized by: One end of the telescopic support rod (9) is inserted into the telescopic groove provided in the support rod (8), and the other end is connected to the connecting block (10) connected to the bottom of the rear end of the telescopic lifting arm (6) through the hinge shaft (7).

5. The overall hoisting construction device for an upright tetrahedral spherical grid structure according to claim 4, characterized in that: A cavity is provided in the middle of the fixing component (14), and a plurality of groups of first springs (20) are arranged around the bottom of the fixing component (14). The bottom of the first spring (20) is connected to the top surface of the connecting rod (12), and the top of the first spring (20) is connected to the connecting plate (19). A fixing rod (21) is provided in the middle of the top of the connecting plate (19), and the fixing rod (21) is parallel to the first fixing hole (15) opened at the top of the connecting rod (12).

6. The overall hoisting construction device for a right-standing quadrangular pyramid spherical grid structure according to claim 5, characterized in that: The middle part of the top of the connecting plate (19) is connected to a pull rod (18), which extends from the top of the fixing assembly (14). By pulling the pull rod (18), the pull rod (18) can drive the connecting plate (19) and the first spring (20) at the bottom of the connecting plate (19) to rise and fall.

7. The overall hoisting construction device for a right-standing quadrangular pyramid spherical grid structure according to claim 6, characterized in that: The top end of the fixing component (14) is provided with a second telescopic groove (23) on both sides of the pull rod (18), a second spring (24) is arranged in the second telescopic groove (23), the rear end of the second spring (24) is connected to the inner side of the outer side of the second telescopic groove (23), and the inner side of the second telescopic groove (23) is connected to a limiting plug (25).

8. The overall hoisting construction device for an upright tetrahedral spherical grid structure according to claim 7, characterized in that: The pull rod (18) is provided with limit slots (22) on both sides of the upper and lower ends. The limit block (25) can be ejected into the limit slot (22) by the elastic force of the second spring (24). The top of the rear end of the limit block (25) is connected to a toggle block (26), and the toggle block (26) extends from the second telescopic slot (23).

9. The overall hoisting construction device for an upright tetrahedral spherical grid structure according to claim 8, characterized in that: A hook (2) is provided at the middle of the top of the center block (1), and the hook (2) is used to connect to the crane. A connecting ring (27) is provided at the middle of the bottom of the support column (3), the middle of the bottom of the connecting block (10) and the bottom of the front end of the telescopic lifting arm (6), and the connecting ring (27) is used to connect to the lifting wire rope.

10. A method for using the overall hoisting construction device for an upright tetrahedral spherical grid structure as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1: Adjustment, pull the pull rod (18), so that the pull rod (18) pulls the connecting plate (19) and the fixed plug rod (21) connected to the middle of the bottom of the connecting plate (19) to disengage from the first fixing hole (15) opened at the top of the connecting rod (12) and the telescopic lifting arm (6), cancel the fixation of the telescopic lifting arm (6), and align the second spring (24) with the limit slots (22) opened on both sides of the bottom end of the pull rod (18). At this time, the second spring (24) pulls the limit plug block through tension (25) pops into the limit slot (22) to fix the contraction of the pull rod (18), and then pushes the sliding block (13) according to the size diameter of the upright tetrahedral spherical grid, so that the sliding block (13) drives the connecting block (10) and the telescopic lifting arm (6) connected to the top of the connecting block (10) to extend outward through the connecting rods (12) on both sides. When the front end of the telescopic lifting arm (6) reaches the outer edge of the upright tetrahedral spherical grid, stop pushing the connecting rod (12); Step 2: Fix, push the limiting plug (25) connected to the top of the rear end of the second spring (24) outward, so that the limiting plug (25) squeezes the second spring (24) and shrinks into the second telescopic groove (23), canceling the limit on the pull rod (18). At this time, the first spring (20) arranged around the bottom of the connecting plate (19) pulls the connecting plate (19) to shrink through the contraction force, and makes the fixed plug (21) in the middle of the bottom of the connecting plate (19) inserted into the first fixing hole (15) opened at the top of the connecting rod (12) and the first telescopic groove (5), the telescopic lifting arm (6) is telescopically fixed, and the limiting plug (25) is inserted into the limiting slots (22) opened on both sides of the top of the pull rod (18) through the tension of the second spring (24), limiting the pull rod (18) again.