CN115676586A

CN115676586A - Steel construction hoisting accessory

Info

Publication number: CN115676586A
Application number: CN202211582041.7A
Authority: CN
Inventors: 吴海艳; 方强
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-12-10
Filing date: 2022-12-10
Publication date: 2023-02-03

Abstract

The invention discloses a steel structure hoisting device, which comprises a support and a support body fixedly arranged on the support, wherein an inclined support frame which is obliquely arranged is fixedly arranged at the top of the support body, a first fixed pulley is rotatably arranged at the bottom end of the right side of the inclined support frame through a pulley frame, a second fixed pulley is rotatably arranged at the top end of the left side of the inclined support frame, steel wire hoisting ropes are respectively arranged on the first fixed pulley and the second fixed pulley in a transmission manner, and one end of each steel wire hoisting rope is fixed at the bottom side of the left end part of the inclined support frame through a connecting ring. This steel construction hoisting accessory not only is convenient for people to hoist and mount the use, hovers when corresponding height when the steel construction product that the lifting hook hoisted moreover, and accessible ratchet assembly prevents the return, still locks the location to the steel wire lifting rope through preventing falling the mechanism, has reduced ratchet assembly like this greatly and has prevented the pressure of gyration, has alleviateed ratchet assembly's wearing and tearing even condemned phenomenon emergence, has further avoided the emergence of incident.

Description

Steel construction hoisting accessory

Technical Field

The invention relates to the technical field of hoisting devices, in particular to a steel structure hoisting device.

Background

Steel structures are structures composed of steel materials and are one of the main building structure types. The structure mainly comprises beam steel, steel columns, steel trusses and other members made of section steel, steel plates and the like, and rust removing and preventing processes such as silanization, pure manganese phosphating, washing drying, galvanization and the like are adopted. The components or parts are typically joined by welds, bolts or rivets. Because of its light dead weight, and construction is simple and convenient, widely apply to fields such as large-scale factory building, venue and super high-rise.

At present, a hoisting device is often needed to hoist a steel structure in the process of construction, for example, the prior art CN214828640U discloses a hoisting device for steel structure construction, which comprises an installation base, an installation frame, a lifting mechanism, an adjusting mechanism, a support rod, a winding mechanism, a connecting frame and a hook; through setting up adjustment mechanism, make hoisting accessory can not only height-adjusting to can adjust the angle of couple, do not need the manual work to hang the couple on the object, it is more convenient.

Although the existing steel structure hoisting device adopts a safety measure that hoisting is carried out by winding the hoisting rope and the hoisting rope is provided with some ratchet assemblies to prevent rotation, the steel structure hoisting device is always prevented from returning by the ratchet assemblies when the hoisting rope is suspended at a corresponding height, so that the abrasion and even scrapping of the ratchet assemblies are aggravated, and safety accidents are still easily caused.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a steel structure hoisting device.

The invention provides a steel structure hoisting device, which comprises a support and a support body fixedly arranged on the support, wherein an inclined strut obliquely arranged is fixedly arranged at the top of the support body, a first fixed pulley is rotatably arranged at the bottom end of the right side of the inclined strut through a pulley yoke, a second fixed pulley is rotatably arranged at the top end of the left side of the inclined strut, steel wire hoisting ropes are respectively arranged on the first fixed pulley and the second fixed pulley in a transmission manner, and one end of each steel wire hoisting rope is fixed at the bottom side of the left end part of the inclined strut through a connecting ring; a lifting wheel assembly is also connected below the second fixed pulley through a steel wire lifting rope in a transmission manner, and a lifting hook for lifting a steel structure is fixedly connected to the bottom side of the lifting wheel assembly;

a bracket is fixedly connected between the supporting body and the left lower side of the bottom of the inclined strut; a transverse frame is fixedly arranged on the left side of the bracket, and an anti-falling mechanism for guiding and positioning the steel wire lifting rope is arranged at the left end part of the transverse frame;

the top of the support is fixedly provided with a U-shaped wheel frame, a winding disc is rotatably arranged in the U-shaped wheel frame, and the other end of the steel wire lifting rope is fixedly wound on the winding disc; a ratchet mechanism for preventing the winding disc from rotating is arranged on the left side of the winding disc;

the support on the right side of the U-shaped wheel frame is fixedly provided with a winding motor, the output end of the winding motor is fixedly sleeved with a first chain wheel, the left side of the first chain wheel is connected with a second chain wheel through chain transmission, the second chain wheel is fixedly sleeved with a rotating shaft, and the other end of the rotating shaft rotates to penetrate into the U-shaped wheel frame and is fixedly sleeved with a winding disc.

Preferably, the anti-falling mechanism comprises two guide holes arranged at the left end part of the cross frame, and the steel wire lifting rope sequentially and movably penetrates through the two guide holes; the transverse frame between the two guide holes is also provided with an installation cavity, two positioning blocks are movably installed in the installation cavity, and the ends, far away from each other, of the two positioning blocks respectively movably penetrate into the guide holes on the two sides and position and lock the steel wire lifting rope;

a screw rod is rotatably installed in the installation cavity through two bearing seats, threaded grooves are respectively formed in the ends, close to each other, of the two positioning blocks, and the positioning blocks are in threaded connection with the screw rod through the threaded grooves; a worm wheel is fixedly sleeved on the screw rod positioned between the two bearing seats, and a worm is meshed on the worm wheel; the top fixed mounting of crossbearer has step motor, and the top of worm rotates and runs through to the outside of crossbearer and with step motor's output fixed connection.

Preferably, one ends of the two positioning blocks, which are far away from each other, are respectively and fixedly provided with a plurality of anti-skid protrusions, and the positioning blocks are matched with the steel wire lifting ropes in an anti-skid positioning manner through the anti-skid protrusions; the inner wall of the guide hole is also provided with a wear-resistant layer; the two ends of the screw rod are respectively provided with an external thread, and the spiral directions of the two external threads on the screw rod are opposite.

Preferably, the top and the bottom of the positioning block in the installation cavity are both fixedly provided with a sliding block, the inner wall of the top and the inner wall of the bottom of the installation cavity are both provided with sliding grooves, and the sliding blocks are slidably installed in the sliding grooves.

Preferably, through holes are formed in the inner walls of the two sides of the mounting cavity, and the positioning blocks penetrate through the through holes in a sliding mode.

Preferably, the ratchet mechanism comprises a U-shaped rotating frame arranged on the left side of the winding disc, and the U-shaped rotating frame is fixedly arranged on the support; an electric push rod is rotatably arranged in the U-shaped rotating frame, and the output end of the electric push rod is fixedly connected with a ratchet chuck; a plurality of ratchet teeth are fixedly arranged on the circumferences of the disk bodies at the two ends of the winding disk, and the ratchet chuck is matched with the ratchet teeth to prevent the winding disk from rotating.

Preferably, the bottom side of the ratchet chuck is fixedly connected with an inclined tension spring which is obliquely arranged, and the inclined bottom end of the inclined tension spring is fixedly connected to the right side of the U-shaped rotating frame.

Preferably, the electric push rod positioned in the U-shaped rotating frame is fixedly provided with two rotating pins, and the electric push rod is rotatably arranged between the inner walls of the front side and the rear side of the U-shaped rotating frame through the two rotating pins.

The invention has the beneficial effects that:

1. according to the invention, a steel structure product is lifted upwards to a required height through the matching of a winding motor, a first chain wheel, a chain, a second chain wheel, a rotating shaft, a winding disc, a steel wire lifting rope, a lifting wheel assembly and a lifting hook; because set up two guiding holes on the crossbearer, two guiding holes all can carry out vertical direction to the steel wire lifting rope like this, ensure to hoist along the upper and lower direction, steel construction product's disorder when can preventing to hoist is moved.

2. According to the invention, by arranging the ratchet mechanism, under the tension action of the oblique tension spring, the ratchet teeth can be prevented from rotating and being occluded by the ratchet chuck, so that the problem of rotation of the steel wire lifting rope on the winding disc can be effectively prevented, and the condition that a steel structure product lifted by the lifting hook falls downwards is avoided.

3. According to the invention, through the arrangement of the anti-falling mechanism, through the cooperation of the stepping motor, the worm wheel and the screw rod, the positioning block can perform thread transmission on two external threads of the screw rod through the thread groove, and further, the outer end of the positioning block can be moved into the guide hole and the steel wire lifting rope can be locked and positioned; and owing to set up the non-skid raised on the locating piece, can ensure more firm that the steel wire lifting rope is fixed a position like this, can further effectually prevent the steel structure product that steel wire lifting rope and lifting hook hoist from appearing the condition that weighs down, ensure more safe and reliable in the hoist and mount use.

4. According to the invention, by arranging the electric push rod, the ratchet chuck can be driven to move left by the contraction of the output end of the electric push rod, so that the meshing positioning of the ratchet chuck on the ratchet teeth can be released, and the steel wire lifting rope is convenient to release, simple in structure and convenient to use.

In conclusion, the steel structure lifting device is convenient for people to hoist and use, when a steel structure product hoisted by the lifting hook is hovered at a corresponding height, the steel structure product can be prevented from returning through the ratchet wheel assembly, and the steel wire lifting rope can be locked and positioned through the positioning block in the anti-falling mechanism, so that the anti-rotation pressure of the ratchet wheel assembly is greatly reduced, the abrasion and even scrapping of the ratchet wheel assembly are reduced, the safety accident is further avoided, and the hoisting and the use are safer and more reliable.

Drawings

FIG. 1 is a schematic structural diagram of a steel structure hoisting device provided by the invention;

FIG. 2 is a partial schematic view of the present invention;

FIG. 3 is an enlarged view of the portion A of FIG. 1;

FIG. 4 is a schematic structural view between a winding disc and ratchet teeth in the invention;

fig. 5 is a schematic structural view of the worm, the worm wheel and the screw in the present invention.

In the figure: 1. a support; 2. a support body; 3. an oblique bracket; 4. a support; 5. a cross frame; 500. a mounting cavity; 501. a guide hole; 502. a wear layer; 6. a pulley yoke; 7. a first fixed pulley; 8. a second fixed pulley; 9. a steel wire lifting rope; 10. a hanging wheel assembly; 11. a hook; 12. a connecting ring; 13. a U-shaped wheel frame; 14. a winding disc; 141. ratchet teeth; 15. a winding motor; 16. a first sprocket; 17. a chain; 18. a second sprocket; 19. a rotating shaft; 20. a U-shaped rotating frame; 21. an inclined tension spring; 22. a ratchet wheel chuck; 23. an electric push rod; 24. a rotation pin; 25. a stepping motor; 26. a worm; 27. a worm gear; 28. a screw; 281. an external thread; 29. positioning blocks; 291. a thread groove; 292. anti-skid protrusions; 30. a slider; 31. and a bearing seat.

Detailed Description

The present invention will be further illustrated with reference to the following specific examples.

Examples

Referring to fig. 1-5, the embodiment provides a steel structure hoisting apparatus, which includes a support 1 and a support body 2 fixedly mounted on the support 1, an obliquely arranged angle bracket 3 is fixedly mounted at the top of the support body 2, a first fixed pulley 7 is rotatably mounted at the bottom end of the right side of the angle bracket 3 through a pulley frame 6, a second fixed pulley 8 is rotatably mounted at the top end of the left side of the angle bracket 3, a steel wire lifting rope 9 is respectively arranged on the first fixed pulley 7 and the second fixed pulley 8 in a transmission manner, and one end of the steel wire lifting rope 9 is fixed at the bottom side of the left end portion of the angle bracket 3 through a connection ring 12; a hanging wheel assembly 10 is also connected below the second fixed pulley 8 through a steel wire hanging rope 9 in a transmission manner, and a hanging hook 11 for hoisting a steel structure is fixedly connected to the bottom side of the hanging wheel assembly 10;

a bracket 4 is fixedly connected between the support body 2 and the left lower side of the bottom of the inclined strut 3; a transverse frame 5 is fixedly arranged on the left side of the bracket 4, and an anti-falling mechanism for guiding and positioning the steel wire lifting rope 9 is arranged at the left end part of the transverse frame 5;

a U-shaped wheel frame 13 is fixedly arranged at the top of the support 1, a winding disc 14 is rotatably arranged in the U-shaped wheel frame 13, and the other end of the steel wire lifting rope 9 is fixedly wound on the winding disc 14; a ratchet mechanism for preventing the winding disc 14 from rotating is arranged on the left side of the winding disc 14;

the support 1 on the right side of the U-shaped wheel frame 13 is also fixedly provided with a winding motor 15, the output end of the winding motor 15 is fixedly sleeved with a first chain wheel 16, the left side of the first chain wheel 16 is connected with a second chain wheel 18 through a chain 17 in a transmission manner, the second chain wheel 18 is fixedly sleeved with a rotating shaft 19, and the other end of the rotating shaft 19 rotates to penetrate into the U-shaped wheel frame 13 and is fixedly sleeved with a winding disc 14.

The anti-falling mechanism comprises two guide holes 501 arranged at the left end part of the transverse frame 5, and the steel wire lifting rope 9 sequentially and movably penetrates through the two guide holes 501; the cross frame 5 between the two guide holes 501 is further provided with a mounting cavity 500, two positioning blocks 29 are movably mounted in the mounting cavity 500, and the ends, far away from each other, of the two positioning blocks 29 respectively movably penetrate through the guide holes 501 at the two sides and position and lock the steel wire lifting rope 9; a screw 28 is rotatably installed in the installation cavity 500 through two bearing seats 31, one ends of the two positioning blocks 29, which are close to each other, are respectively provided with a thread groove 291, and the positioning blocks 29 are in threaded connection with the screw 28 through the thread grooves 291; a worm wheel 27 is fixedly sleeved on the screw 28 positioned between the two bearing blocks 31, and a worm 26 is meshed on the worm wheel 27; the top of the cross frame 5 is fixedly provided with a stepping motor 25, and the top end of the worm 26 rotates to penetrate to the outside of the cross frame 5 and is fixedly connected with the output end of the stepping motor 25.

Wherein, the ends of the two positioning blocks 29 far away from each other are respectively fixedly provided with a plurality of anti-skid protrusions 292, and the positioning blocks 29 are in anti-skid positioning fit with the steel wire lifting rope 9 through the anti-skid protrusions 292; the inner wall of the guide hole 501 is also provided with a wear-resistant layer 502; the two ends of the screw 28 are respectively provided with an external thread 281, and the two external threads 281 on the screw 28 are arranged in opposite spiral directions.

Wherein, the top and the bottom of the positioning block 29 in the installation cavity 500 are both fixedly provided with a sliding block 30, the inner wall of the top and the inner wall of the bottom of the installation cavity 500 are both provided with a sliding groove, and the sliding block 30 is slidably installed in the sliding groove; through holes are formed in the inner walls of the two sides of the installation cavity 500, and the positioning block 29 penetrates through the through holes in a sliding manner.

The ratchet mechanism comprises a U-shaped rotating frame 20 arranged on the left side of the winding disc 14, and the U-shaped rotating frame 20 is fixedly arranged on the support 1; an electric push rod 23 is rotatably arranged in the U-shaped rotating frame 20, and the output end of the electric push rod 23 is fixedly connected with a ratchet chuck 22; a plurality of ratchet teeth 141 are fixedly arranged on the circumference of the disk bodies at the two ends of the winding disk 14, and a ratchet chuck 22 is matched with the ratchet teeth 141 for preventing the winding disk 14 from rotating.

Wherein, the bottom side of the ratchet chuck 22 is fixedly connected with an inclined tension spring 21 which is obliquely arranged, and the inclined bottom end of the inclined tension spring 21 is fixedly connected with the right side of the U-shaped rotating frame 20; two rotating pins 24 are fixedly arranged on an electric push rod 23 positioned in the U-shaped rotating frame 20, and the electric push rod 23 is rotatably arranged between the inner walls of the front side and the rear side of the U-shaped rotating frame 20 through the two rotating pins 24.

As shown in fig. 1 to 5, in the steel structure hoisting device provided by the invention, in the hoisting use process, the positioning block 29 in the anti-falling mechanism is accommodated in the installation cavity 500. When in use: the first chain wheel 16 is driven to rotate by the winding motor 16, the rotating shaft 19 and the winding disc 14 are driven to rotate by the transmission of the chain 17 and the second chain wheel 18, the steel wire lifting rope 9 can be wound by the rotation of the winding disc 14, and the steel structure product hoisted by the lifting wheel assembly 10 and the lifting hook 11 is driven to be hoisted upwards to a required height by the winding process of the steel wire lifting rope 9; because two guide holes 501 are arranged on the cross frame 5, the two guide holes 501 can vertically guide the steel wire lifting rope 9, and the conveying and hoisting in the vertical direction are ensured.

And, owing to set up ratchet mechanism, can prevent the condition of gyration like this in the rolling dish 14 is rotatory, rolling dish 14 can drive ratchet tooth 141 rotatory in rotatory promptly, ratchet dop 22 is under oblique tension spring 21 pulling force effect this moment, rolling dish 14 just can prevent the interlock of gyration through ratchet dop 22 to ratchet tooth 141 in the rolling rotates like this, and then can effectually prevent that steel wire lifting rope 9 on rolling dish 14 from appearing the problem of gyration, thereby the condition that the steel structure product that lifting hook 11 hoisted falls downwards has been avoided.

As a further improvement, due to the further arrangement of the anti-falling mechanism, when a steel structure product hoisted by the hook 11 is hoisted and hovered at a certain height, the ratchet teeth 141 can be matched with the ratchet chuck 22 in a rotation prevention manner, and the steel wire lifting rope 9 can be locked and positioned by the positioning block 29 in the anti-falling mechanism; the worm 26 is driven to rotate by the stepping motor 25, the worm 26 is meshed with the worm wheel 27 for transmission when rotating to drive the screw 28 to rotate, and due to the fact that the spiral directions of the two external threads 281 on the screw 28 are opposite, when the screw 28 rotates, the positioning block 29 can perform thread transmission on the two external threads 281 of the screw 28 through the thread groove 291, and then the outer end of the positioning block 29 can be moved into the guide hole 501 and locked and positioned on the steel wire lifting rope 9; and because the anti-skid protrusions 292 are arranged on the positioning blocks 29, the steel wire lifting rope 9 can be positioned more firmly, the steel structure product lifted by the steel wire lifting rope 9 and the lifting hook 11 can be further effectively prevented from falling, and the lifting and the using process are safer and more reliable.

In addition, when the ratchet teeth 141 on the winding disc 14 do not need to be occluded, the electric push rod 23 is arranged, the ratchet chuck 22 can be driven to move left by contraction of the output end of the electric push rod 23, and then the occlusion positioning of the ratchet teeth 141 by the ratchet chuck 22 can be released, so that the steel wire lifting rope 9 can be conveniently released, and the steel wire lifting rope releasing device is simple in structure and convenient to use.

In conclusion, when a steel structure product hoisted by the lifting hook 11 is hovered at a corresponding height, the steel structure product can be prevented from returning through the ratchet wheel assembly, and the steel wire lifting rope 9 is locked and positioned through the positioning block 29 in the anti-falling mechanism, so that the anti-return pressure of the ratchet wheel assembly is greatly reduced, the phenomenon that the ratchet wheel assembly is worn or even scrapped is reduced, safety accidents are further avoided, and the hoisting is safer and more reliable in use.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. A steel structure hoisting device comprises a support (1) and a support body (2) fixedly mounted on the support (1), and is characterized in that an inclined strut (3) which is obliquely arranged is fixedly mounted at the top of the support body (2), a first fixed pulley (7) is rotatably mounted at the bottom end of the right side of the inclined strut (3) through a pulley frame (6), a second fixed pulley (8) is rotatably mounted at the top end of the left side of the inclined strut (3), steel wire hoisting ropes (9) are respectively arranged on the first fixed pulley (7) and the second fixed pulley (8) in a transmission manner, and one end of each steel wire hoisting rope (9) is fixed at the bottom side of the left end part of the inclined strut (3) through a connecting ring (12); a hanging wheel assembly (10) is also connected below the second fixed pulley (8) through a steel wire hanging rope (9) in a transmission manner, and a hanging hook (11) for hoisting a steel structure is fixedly connected to the bottom side of the hanging wheel assembly (10);

a bracket (4) is fixedly connected between the support body (2) and the left lower side of the bottom of the inclined strut (3); a transverse frame (5) is fixedly arranged on the left side of the bracket (4), and an anti-falling mechanism for guiding and positioning the steel wire lifting rope (9) is arranged at the left end part of the transverse frame (5);

a U-shaped wheel frame (13) is fixedly installed at the top of the support (1), a winding disc (14) is rotatably installed in the U-shaped wheel frame (13), and the other end of the steel wire lifting rope (9) is fixedly wound on the winding disc (14); a ratchet mechanism for preventing the winding disc (14) from rotating is arranged on the left side of the winding disc (14);

the winding mechanism is characterized in that a winding motor (15) is fixedly mounted on a support (1) on the right side of the U-shaped wheel frame (13), a first chain wheel (16) is fixedly sleeved on the output end of the winding motor (15), the left side of the first chain wheel (16) is connected with a second chain wheel (18) through a chain (17) in a transmission mode, a rotating shaft (19) is fixedly sleeved on the second chain wheel (18), and the other end of the rotating shaft (19) rotates to penetrate into the U-shaped wheel frame (13) and is fixedly sleeved with a winding disc (14).

2. The steel structure hoisting device according to claim 1, wherein the anti-falling mechanism comprises two guide holes (501) arranged at the left end part of the cross frame (5), and the steel wire lifting rope (9) sequentially and movably penetrates through the two guide holes (501); a mounting cavity (500) is further arranged on the cross frame (5) between the two guide holes (501), two positioning blocks (29) are movably mounted in the mounting cavity (500), and the ends, far away from each other, of the two positioning blocks (29) respectively movably penetrate through the guide holes (501) on the two sides and position and lock the steel wire lifting rope (9);

a screw rod (28) is rotatably installed in the installation cavity (500) through two bearing seats (31), one ends, close to each other, of the two positioning blocks (29) are respectively provided with a thread groove (291), and the positioning blocks (29) are in threaded connection with the screw rod (28) through the thread grooves (291); a worm wheel (27) is fixedly sleeved on the screw rod (28) positioned between the two bearing seats (31), and a worm (26) is meshed on the worm wheel (27); step motor (25) is fixedly mounted at the top of cross frame (5), and the top end of worm (26) rotates and runs through to the outside of cross frame (5) and is fixedly connected with the output end of step motor (25).

3. The steel structure hoisting device according to claim 2, wherein one ends of the two positioning blocks (29) far away from each other are respectively and fixedly provided with a plurality of anti-skid protrusions (292), and the positioning blocks (29) are in anti-skid positioning fit with the steel wire hoisting ropes (9) through the anti-skid protrusions (292); the inner wall of the guide hole (501) is also provided with a wear-resistant layer (502); the two ends of the screw rod (28) are respectively provided with an external thread (281), and the spiral directions of the two external threads (281) on the screw rod (28) are opposite.

4. The steel structure hoisting device according to claim 2, wherein the top and the bottom of the positioning block (29) in the installation cavity (500) are both fixedly provided with sliding blocks (30), the inner walls of the top and the bottom of the installation cavity (500) are both provided with sliding grooves, and the sliding blocks (30) are slidably installed in the sliding grooves.

5. The steel structure hoisting device of claim 2, wherein the inner walls of the two sides of the installation cavity (500) are provided with through holes, and the positioning block (29) is slidably inserted through the through holes.

6. The steel structure hoisting device according to claim 1, wherein the ratchet mechanism comprises a U-shaped rotating frame (20) arranged on the left side of the winding disc (14), and the U-shaped rotating frame (20) is fixedly arranged on the support (1); an electric push rod (23) is rotatably arranged in the U-shaped rotating frame (20), and the output end of the electric push rod (23) is fixedly connected with a ratchet chuck (22); a plurality of ratchet teeth (141) are fixedly arranged on the circumferences of the disc bodies at the two ends of the winding disc (14), and the ratchet chuck (22) is matched with the ratchet teeth (141) to prevent the winding disc (14) from rotating.

7. The steel structure hoisting device according to claim 6, wherein the bottom side of the ratchet chuck (22) is fixedly connected with an inclined tension spring (21) which is obliquely arranged, and the inclined bottom end of the inclined tension spring (21) is fixedly connected to the right side of the U-shaped rotating frame (20).

8. The steel structure hoisting device of claim 7, wherein two rotating pins (24) are fixedly installed on the electric push rod (23) positioned in the U-shaped rotating frame (20), and the electric push rod (23) is rotatably installed between the inner walls of the front side and the rear side of the U-shaped rotating frame (20) through the two rotating pins (24).