Construction methods for pre-assembly and hoisting of large cantilever flange steel box girders

Abstract

This invention relates to a method for pre-assembling and hoisting a large cantilever flange steel box girder, comprising the following steps: steel box girder segments are temporarily supported and installed using a bracket method; steel cantilever installation is carried out based on the steel box girder bridge deck; a steel cantilever hoisting stabilizing bracket is installed and adjusted on the steel box girder bridge deck; a welding platform is suspended below the first steel cantilever segment, controlling a sliding crane one to slide outwards towards the outside of the steel box girder, while simultaneously controlling a sliding crane two to move to the other side to balance the load on the steel cantilever; welding operations are carried out on the steel cantilever; the connection between the sliding crane one and the steel cantilever is disconnected, and the hoisting and welding of the next steel cantilever segment is performed. The beneficial effects of this invention are: the sliding crane one used to hoist the steel cantilever segment and the sliding crane two used to hoist the counterweight are slidably connected by crane tracks, effectively avoiding the influence of the environment on the hoisting operation, while ensuring the safety and efficiency of the hoisting operation; the welding platform relying on the sliding of the steel cantilever and steel box girder ensures the safety of welding personnel.

Description

TECHNICAL FIELD

[0001] The present application relates to a large cantilever flange steel box girder pre-assembling and hoisting operation, in particular to a large cantilever flange steel box girder pre-assembling and hoisting construction method. BACKGROUND

[0002] When the steel structure box girder construction is carried out, the construction method of factory prefabrication and on-site splicing is usually adopted. After the steel box girder segment is prefabricated, it needs to be pre-assembled in the factory, and after the pre-assembly inspection is qualified, it can be transported to the construction site for splicing. The traditional splicing jig frame is usually a steel support welded according to the size of the steel box girder, which can ensure the splicing precision, but the steel box girder segment hoisting operation is large in amount and difficult to be applied to some non-standard size girder segments. When the steel box girder segment is spliced on site, in order to reduce the workload of setting up temporary supports, only the main body segment of the box girder is usually supported by the temporary support, and the steel cantilever on both sides is hoisted to the air by the crane, and then welded and fixed with the main body segment of the box girder. However, the hoisting operation is greatly affected by the environment, the ground on both sides of the bridge needs to be treated to ensure the bearing capacity, a temporary construction trestle needs to be set up when the bridge crosses a river, and the hoisting operation needs to be stopped in windy weather, which increases the construction cost and reduces the construction efficiency. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings in the prior art and provide a large cantilever flange steel box girder pre-assembling and hoisting construction method.

[0004] The large cantilever flange steel box girder pre-assembling and hoisting construction device comprises a pre-assembly jig frame and a steel cantilever hoisting stable support, and the surface of the steel cantilever and the side edge of the steel box girder are each provided with a limiting channel steel;

[0005] The pre-assembly jig frame comprises a fixed hydraulic telescopic rod and a movable hydraulic telescopic rod, and the movable hydraulic telescopic rod is slidably connected with a sliding track; the top end of the fixed hydraulic telescopic rod is provided with a first supporting pulley, and the first supporting pulley contacts the lower surface of the steel box girder or the steel cantilever; the top end of the movable hydraulic telescopic rod is provided with a limiting pulley, and the limiting pulley contacts the side edge of the steel box girder or the steel cantilever;

[0006] The steel cantilever hoisting stable support comprises a horizontal truss, a supporting truss, a trolley track, a sliding trolley one and a sliding trolley two, the horizontal truss is supported on the supporting truss, two hydraulic legs are arranged at the lower end of the supporting truss, and each hydraulic leg is provided with an extension support foot and a second supporting pulley at the lower end; the trolley track is fixed on the horizontal truss, the sliding trolley one for hoisting the steel cantilever segment and the sliding trolley two for hoisting the weight block are slidably connected with the trolley track; a welding operation platform is hung below the first steel cantilever.

[0007] As preferred, the fixed hydraulic telescopic rod is fixed by transverse connection of connecting rods, and the lower end of the movable hydraulic telescopic rod is provided with a supporting pulley block connected with a sliding track; a brake block is arranged in the sliding track and connected with the supporting pulley block.

[0008] As preferred, limit blocks are arranged at the two ends of the crown block track; the sliding crown block one and the sliding crown block two each include a rotating motor, a steel wire rope, a pulley block and a telescopic sleeve, the rotating motor is fixedly installed on the pulley block, the upper end of the telescopic sleeve is fixed below the pulley block, one end of the steel wire rope is fixed on the rotating motor, and the other end of the steel wire rope is drawn out from the telescopic sleeve; the telescopic sleeve of the sliding crown block one is provided with a telescopic supporting leg, a locking pin shaft is arranged on the telescopic sleeve, a compression spring is arranged between the telescopic supporting leg and the telescopic sleeve, a movable supporting leg is arranged below the telescopic supporting leg, a lifting ring is arranged on the steel cantilever, and the lower end of the steel wire rope is tied to the lifting ring on the steel cantilever.

[0009] As preferred, safety guardrails, ladders and ladder guardrails are arranged on the welding operation platform, and mobile pulleys are arranged at the two ends of the operation platform and supported in limit channel steels on the surface of the steel cantilever and the side edges of the steel box girder respectively, and a temporary supporting pulley is arranged on one side of the welding operation platform.

[0010] The method for using the large-cantilever flange steel box girder pre-assembly and hoisting construction device comprises the following construction steps:

[0011] Step one: assemble the pre-assembly jig, adjust the fixed hydraulic telescopic rod to support the steel box girder and the steel cantilever segment, and adjust the movable hydraulic telescopic rod to support the side edges of each segment;

[0012] Step two: temporarily support and weld the steel box girder segments by the support method to form a whole, and install the steel cantilever on the basis of the steel box girder bridge deck;

[0013] Step three: install and debug the steel cantilever hoisting stable support on the steel box girder bridge deck, slide to the specified position through the second supporting pulley, and hoist the weight block through the sliding crown block two;

[0014] Step four: hoist the steel cantilever segment through the sliding crown block one, and hang the welding operation platform below the steel cantilever, control the sliding crown block one to support the mobile pulley at one end of the welding operation platform in the limit channel steel of the steel box girder;

[0015] Step five: separate the welding operation platform from the steel cantilever, weld the steel cantilever on the basis of the welding operation platform, and move the welding operation platform along the limit channel steel;

[0016] Step six: separate the sliding crown block one from the steel cantilever, move the sliding crown block one and the sliding crown block two inwardly and transversely, and repeat steps four and five until the steel cantilever construction is completed.

[0017] As preferred, the pre-assembled jig in the step one comprises fixed hydraulic telescopic rods and movable hydraulic telescopic rods, the fixed hydraulic telescopic rods are horizontally connected by connecting rods, the lower ends of the movable hydraulic telescopic rods are arranged on the support pulley set which is supported in the sliding track, the top ends of the fixed hydraulic telescopic rods are provided with support pulleys which are close to the lower surface of the steel box girder or the steel cantilever, the top ends of the movable hydraulic telescopic rods are provided with limit pulleys which are close to the side edges of the steel box girder or the steel cantilever, and the sliding track is provided with a brake block which is close to the support pulley set.

[0018] As preferred, after the steel cantilever hoisting stable support is slid to the specified position through the second support pulley in the step three, the steel cantilever hoisting stable support is supported by the telescopic support leg through the adjustment of the hydraulic support leg, the sliding trolley one and the sliding trolley two are controlled to move along the trolley track, the performance of the sliding trolley one and the sliding trolley two is inspected, and the sliding trolley two is used to hoist the weight block after the inspection is qualified.

[0019] As preferred, in the step four, one end of the welding operation platform is supported in the limit channel steel on the surface of the steel cantilever through the movable pulley, and the other end is hung below the steel cantilever through the temporary steel wire rope, the sliding trolley two with the weight block is controlled to move to the other side to balance the load of the steel cantilever while the sliding trolley one is controlled to slide to the outside of the steel box girder, the steel cantilever segment is lowered after the sliding trolley one slides to the specified position, the telescopic sleeve on the sliding trolley one is locked by using the locking pin shaft when the distance between the top surface of the steel cantilever and the top surface of the steel box girder is a certain height, the steel cantilever is lowered to be flush with the steel box girder, and the movable pulley at the other end of the welding operation platform is supported in the limit channel steel on the side edge of the steel box girder.

[0020] As preferred, in the step five, the temporary steel wire rope between the welding operation platform and the steel cantilever is removed, and then the welding operation of the steel cantilever is carried out, the welding seam at the bottom of the steel cantilever is carried out by relying on the welding operation platform, the welding operation platform is moved along the limit channel steel on the surface of the steel cantilever and the side edge of the steel box girder by the workers entering the welding operation platform through the ladder.

[0021] The beneficial effects of the present application are:

[0022] 1) The large cantilever flange steel box girder pre-assembled jig provided by the present application can adapt to different structure sizes and ensure the pre-assembled precision and improve the operation efficiency.

[0023] 2) The steel cantilever hoisting stable support provided by the present application, the sliding trolley one for hoisting the steel cantilever segment and the sliding trolley two for hoisting the weight block are slidably connected to the trolley track, which can effectively avoid the influence of the environment on the hoisting operation and ensure the safety and efficiency of the hoisting operation.

[0024] 3) the welding operation platform which relies on the steel cantilever and the steel box beam sliding has the advantages of light self-weight and simple structure, ensures the safety of the welding operation personnel, and improves the welding operation quality. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a schematic diagram of the steel box beam module pre-assembly jig;

[0026] Figure 2 is a schematic diagram of the steel cantilever hoisting;

[0027] Figure 3 is a schematic diagram of the steel cantilever hoisting in place;

[0028] Figure 4 is a schematic diagram of the steel cantilever hoisting;

[0029] Figure 5 is a schematic diagram of the sliding trolley two connecting weight pressing structure;

[0030] Figure 6 is a schematic diagram of the welding operation platform structure.

[0031] In the figure, 11 is a steel box beam, 12 is a steel cantilever, 13 is a limiting channel steel, 21 is a fixed hydraulic telescopic rod, 22 is a first supporting pulley, 23 is a connecting rod, 24 is a movable hydraulic telescopic rod, 25 is a limiting pulley, 26 is a supporting pulley set, 27 is a brake block, 28 is a sliding track, 31 is a horizontal truss, 32 is a supporting truss, 33 is a hydraulic support leg, 34 is a telescopic support foot, 35 is a second supporting pulley, 36 is a trolley track, 37 is a limiting block, 41 is a sliding trolley one, 42 is a sliding trolley two, 43 is a rotating motor, 44 is a steel wire rope, 45 is a pulley set, 46 is a telescopic sleeve, 47 is a weight pressing block, 48 is a locking pin shaft, 49 is a movable support foot, 410 is a compression spring, 411 is a telescopic support leg, 412 is a lifting ring, 51 is a welding operation platform, 52 is a safety guardrail, 53 is a ladder, 54 is a ladder guardrail, 55 is a movable pulley, 56 is a temporary supporting pulley, and 57 is a temporary steel wire rope. DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the embodiments. The following description of the embodiments is only for the purpose of helping to understand the application. It should be noted that for ordinary people in the technical field, some modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0033] Example One

[0034] As an example, as Figures 1 to 6As shown, the large cantilever flange steel box girder pre-assembling and hoisting construction device comprises a pre-assembling jig and a steel cantilever hoisting stable support, and the surface of the steel cantilever 12 and the side edge of the steel box girder 11 are both provided with a limiting channel steel 13;

[0035] The pre-assembling jig comprises a fixed hydraulic telescopic rod 21 and a movable hydraulic telescopic rod 24, and the movable hydraulic telescopic rod 24 is slidably connected with a sliding track 28; the top end of the fixed hydraulic telescopic rod 21 is provided with a first supporting pulley 22, and the first supporting pulley 22 contacts the lower surface of the steel box girder 11 or the steel cantilever 12; the top end of the movable hydraulic telescopic rod 24 is provided with a limiting pulley 25, and the limiting pulley 25 contacts the side edge of the steel box girder 11 or the steel cantilever 12; the fixed hydraulic telescopic rod 21 is transversely connected and fixed through a connecting rod 23, and the lower end of the movable hydraulic telescopic rod 24 is provided with a supporting pulley set 26, and the supporting pulley set 26 is connected with the sliding track 28; the sliding track 28 is provided with a brake block 27, and the brake block 27 is connected with the supporting pulley set 26.

[0036] The steel cantilever hoisting stable support comprises a horizontal truss 31, a supporting truss 32, a trolley track 36, a sliding trolley one 41 and a sliding trolley two 42, the horizontal truss 31 is supported on the supporting truss 32, the supporting truss 32 is provided with two hydraulic legs 33 at the lower end, and the lower end of each hydraulic leg 33 is provided with a telescopic support foot 34 and a second supporting pulley 35; the trolley track 36 is fixed on the horizontal truss 31, the sliding trolley one 41 for hoisting the steel cantilever 12 segment and the sliding trolley two 42 for hoisting the weight block 47 are slidably connected with the trolley track 36; a welding operation platform 51 is hung below the first steel cantilever 12.

[0037] The welding operation platform 51 is provided with a safety guard 52, a ladder 53 and a ladder guard 54, and the both ends of the operation platform 51 are respectively provided with a movable pulley 55, the movable pulley 55 is respectively supported in the limiting channel steel 13 on the surface of the steel cantilever 12 and the side edge of the steel box girder 11, and one side of the welding operation platform 51 is provided with a temporary supporting pulley 56.

[0038] The both ends of the trolley track 36 are provided with limiting blocks 37; the sliding trolley one 41 and the sliding trolley two 42 both comprise a rotating motor 43, a steel wire rope 44, a pulley set 45 and a telescopic sleeve 46, the rotating motor 43 is fixedly installed on the pulley set 45, the upper end of the telescopic sleeve 46 is fixed below the pulley set 45, one end of the steel wire rope 44 is fixed on the rotating motor 43, and the other end of the steel wire rope 44 is pulled out from the telescopic sleeve 46; the lower end of the telescopic sleeve 46 of the sliding trolley one 41 is provided with a telescopic leg 411, the telescopic sleeve 46 is provided with a locking pin 48, a compression spring 410 is arranged between the telescopic leg 411 and the telescopic sleeve 46, an active support foot 49 is arranged below the telescopic leg 411, a lifting ring 412 is arranged on the steel cantilever 12, and the lower end of the steel wire rope 44 is tied to the lifting ring 412 on the steel cantilever 12.

[0039] Example two

[0040] As another embodiment, the hoisting construction method of the large cantilever flange steel box girder pre-assembly and hoisting construction device in embodiment one includes the following construction steps:

[0041] Step one, after the manufacture of each segment of the steel box girder bridge is completed, the segment pre-assembly operation is carried out. First, the pre-assembly jig is adjusted according to the structural size of the steel box girder 11 and the steel cantilever 12. The height of the fixed hydraulic telescopic rod 21 is adjusted to support the steel box girder 11 and the steel cantilever 12 segment. The height and position of the movable hydraulic telescopic rod 24 are adjusted to support the side of each segment. Then the steel box girder 11 and the steel cantilever 12 segment are hoisted to the pre-assembly jig, and the manufacturing precision of each segment is inspected. After the inspection is qualified, each segment is transported to the construction site for assembly operation. The pre-assembly jig is composed of fixed hydraulic telescopic rod 21 and movable hydraulic telescopic rod 24. The fixed hydraulic telescopic rod 21 is fixed by transverse connection through the connecting rod 23. The lower end of the movable hydraulic telescopic rod 24 is arranged on the support pulley block 26, which is supported in the sliding track 28. The top end of the fixed hydraulic telescopic rod 21 has a first support pulley 22, which is in close contact with the lower surface of the steel box girder 11 or the steel cantilever 12. The top end of the movable hydraulic telescopic rod 24 has a limit pulley 25, which is in close contact with the side of the steel box girder 11 or the steel cantilever 12. The sliding track 28 is provided with a brake block 27, which is in close contact with the support pulley block 26.

[0042] Step two, after each segment is transported to the construction site, the steel box girder 11 segment is temporarily supported by the support method, and then the steel box girder 11 segments are welded to form a whole. After the steel box girder 11 segment is installed in place, the steel cantilever 12 is transported to the steel box girder 11 bridge, and the installation of the steel cantilever 12 is carried out relying on the steel box girder 11 bridge.

[0043] Step three, install and debug the steel suspension cantilever hoisting stabilizing support on the bridge deck of the steel box girder 11, after the steel suspension cantilever hoisting stabilizing support is slid to the designated position through the second supporting pulley 35, the steel suspension cantilever hoisting stabilizing support is supported by the telescopic supporting leg 34, then the sliding trolley one 41 and the sliding trolley two 42 are controlled to move along the trolley track 36, the performance of the sliding trolley one 41 and the sliding trolley two 42 is inspected, after the inspection is qualified, the sliding trolley two 42 is controlled to hoist the weight block 47; the steel suspension cantilever hoisting stabilizing support is composed of the horizontal truss 31, the supporting truss 32, the trolley track 36, the sliding trolley one 41 and the sliding trolley two 42, the horizontal truss 31 is supported on the supporting truss 32, the supporting truss 32 is provided with two hydraulic supporting legs 33 at the lower end, the lower end of the hydraulic supporting leg 33 is respectively provided with the telescopic supporting leg 34 and the second supporting pulley 35; the trolley track 36 is fixed on the horizontal truss 31, the sliding trolley one 41 and the sliding trolley two 42 are supported on the trolley track 36; the trolley track 36 is provided with the limiting block 37 at both ends. The sliding trolley one 41 and the sliding trolley two 42 are composed of the rotating motor 43, the steel wire rope 44, the pulley set 45, the telescopic sleeve 46, the rotating motor 43 is installed and fixed on the pulley set 45, the upper end of the telescopic sleeve 46 is fixed below the pulley set 45, one end of the steel wire rope 44 is fixed on the rotating motor 43, the other end of the steel wire rope 44 is pulled out from the telescopic sleeve 46; the telescopic sleeve 46 is provided with the telescopic supporting leg 411 at the lower end, the telescopic sleeve 46 is provided with the locking pin 48, the telescopic supporting leg 411 and the telescopic sleeve 46 are provided with the compression spring 410, the telescopic supporting leg 411 is provided with the movable supporting leg 49 below, the lower end of the steel wire rope 44 is tied to the lifting ring 412 on the steel suspension cantilever 12.

[0044] Step four, the steel suspension cantilever 12 segment is hoisted through the sliding trolley one 41, and the welding operation platform 51 is hung below the first steel suspension cantilever 12, one end of the welding operation platform 51 is supported in the limiting channel steel 13 on the surface of the steel suspension cantilever 12 through the moving pulley 55, the other end is hung below the steel suspension cantilever 12 through the temporary steel wire rope 57; the sliding trolley one 41 is controlled to slide to the outside of the steel box girder 11, and the sliding trolley two 42 is controlled to move to the other side to balance the load of the steel suspension cantilever 12, the anti-overturning capacity of the steel suspension cantilever hoisting stabilizing support is improved; after the sliding trolley one 41 is slid to the designated position, the steel suspension cantilever 12 segment is slowly lowered, when the top surface of the steel suspension cantilever 12 is a certain height from the top surface of the steel box girder 11, the telescopic sleeve 46 on the sliding trolley one 41 is locked by using the locking pin 48, then the steel suspension cantilever 12 is slowly lowered to be flush with the steel box girder 11, and the moving pulley 55 at the other end of the welding operation platform 51 is supported in the limiting channel steel 13 on the side of the steel box girder 11; the welding operation platform 51 is provided with the safety guard 52, the ladder 53 and the ladder guard 54, and is provided with the moving pulley 55 at both ends, the moving pulley 55 is supported in the limiting channel steel 13 on the surface of the steel suspension cantilever 12 and the side of the steel box girder 11 respectively, one side of the welding operation platform 51 is provided with the temporary supporting pulley 56.

[0045] Step five, the temporary steel wire rope 57 between the welding operation platform 51 and the steel cantilever 12 is removed, and then the welding operation of the steel cantilever 12 is carried out, the weld at the bottom of the steel cantilever 12 is carried out by relying on the welding operation platform 51, the operator enters the welding operation platform 51 through the ladder 53, and the welding operation platform 51 moves along the limiting channel steel 13 on the surface of the steel cantilever 12 and the side edge of the steel box girder 11.

[0046] Step six, the connection between the sliding trolley one 41 and the steel cantilever 12 is released, then the sliding trolley one 41 and the sliding trolley two 42 are moved inward and transversely, the hoisting operation and the welding operation of the next segment of the steel cantilever 12 are carried out according to the method described in steps four and five, and the steel cantilever 12 is welded and fixed with the last segment of the steel cantilever 12 until all the steel cantilevers 12 are constructed.

Claims

1. A method for using a large cantilevered flange steel box girder pre-assembly and hoisting construction device, characterized in that, The large cantilever flange steel box girder pre-assembling and hoisting construction device comprises a pre-assembling jig and a steel cantilever hoisting stable support, and the surface of the steel cantilever (12) and the side edge of the steel box girder (11) are each provided with a limiting channel steel (13); The pre-assembling jig comprises a fixed hydraulic telescopic rod (21) and a movable hydraulic telescopic rod (24), and the movable hydraulic telescopic rod (24) is slidably connected with a sliding track (28); the top end of the fixed hydraulic telescopic rod (21) is provided with a first supporting pulley (22), and the first supporting pulley (22) contacts the lower surface of the steel box girder (11) or the steel cantilever (12); the top end of the movable hydraulic telescopic rod (24) is provided with a limiting pulley (25), and the limiting pulley (25) contacts the side edge of the steel box girder (11) or the steel cantilever (12); The steel cantilever hoisting stable support comprises a horizontal truss (31), a supporting truss (32), a crown block track (36), a sliding crown block one (41) and a sliding crown block two (42), the horizontal truss (31) is supported on the supporting truss (32), the supporting truss (32) is provided with two hydraulic supporting legs (33) at the lower end, and the lower end of each hydraulic supporting leg (33) is provided with an expansion supporting leg (34) and a second supporting pulley (35); the crown block track (36) is fixed on the horizontal truss (31), the sliding crown block one (41) for hoisting the steel cantilever (12) segment and the sliding crown block two (42) for hoisting the weight block (47) are slidably connected with the crown block track (36); the first steel cantilever (12) is hung with a welding operation platform (51) below; The method comprises the following steps: Step one, assemble the pre-assembling jig, adjust the fixed hydraulic telescopic rod (21) to support the steel box girder (11) and the steel cantilever (12) segment, and adjust the movable hydraulic telescopic rod (24) to support the side edge of each segment; Step two, temporarily support the steel box girder (11) segment by the support method and weld to form a whole; rely on the steel box girder (11) bridge to carry out the installation operation of the steel cantilever (12); Step three, install and debug the steel cantilever hoisting stable support on the steel box girder (11) bridge, and then slide to the specified position through the second supporting pulley (35), and then hoist the weight block (47) through the sliding crown block two (42); Step four, hoist the steel cantilever (12) segment through the sliding crown block one (41), and hang the welding operation platform (51) below the steel cantilever (12), and control the sliding crown block one (41) to make the movable pulley (55) at one end of the welding operation platform (51) support in the limiting channel steel (13) of the steel box girder (11); Step five, separate the welding operation platform (51) from the steel cantilever (12), rely on the welding operation platform (51) to weld the steel cantilever (12), and move the welding operation platform (51) along the limiting channel steel (13); Step six, separate the sliding crown block one (41) from the steel cantilever (12), move the sliding crown block one (41) and the sliding crown block two (42) to the inside laterally, and repeat steps four and five until the steel cantilever (12) construction is completed.

2. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 1, characterized in that, The fixed hydraulic telescopic rod (21) is transversely connected and fixed through the connecting rod (23), and the lower end of the movable hydraulic telescopic rod (24) is provided with a supporting pulley block (26), and the supporting pulley block (26) is connected with a sliding track (28); the sliding track (28) is provided with a brake block (27), and the brake block (27) is connected with the supporting pulley block (26).

3. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 1, characterized in that, The both ends of the crown block rail (36) are provided with limit blocks (37); the sliding crown block one (41) and the sliding crown block two (42) both include a rotating motor (43), a steel wire rope (44), a pulley block (45) and an expansion sleeve (46), the rotating motor (43) is fixedly installed on the pulley block (45), the upper end of the expansion sleeve (46) is fixed below the pulley block (45), one end of the steel wire rope (44) is fixed on the rotating motor (43), and the other end of the steel wire rope (44) is drawn out from the expansion sleeve (46); the lower end of the expansion sleeve (46) of the sliding crown block one (41) is provided with an expansion supporting leg (411), the expansion sleeve (46) is provided with a locking pin shaft (48), a compression spring (410) is arranged between the expansion supporting leg (411) and the expansion sleeve (46), and the lower end of the expansion supporting leg (411) is provided with a movable supporting leg (49); the steel cantilever (12) is provided with a lifting ring (412), and the lower end of the steel wire rope (44) is tied to the lifting ring (412) on the steel cantilever (12).

4. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 1, characterized in that, The welding operation platform (51) is provided with a safety guardrail (52), a ladder (53) and a ladder guardrail (54), and the both ends of the operation platform (51) are respectively provided with movable pulleys (55) supported in the limit channel steel (13) on the surface of the steel cantilever (12) and the side of the steel box girder (11), and one side of the welding operation platform (51) is provided with a temporary supporting pulley (56).

5. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 1, characterized in that, After the step three of adjusting the steel cantilever hoisting stable support to slide to the specified position through the second supporting pulley (35), the hydraulic supporting leg (33) is adjusted to support the steel cantilever hoisting stable support by the expansion supporting leg (34); the sliding crown block one (41) and the sliding crown block two (42) are controlled to move along the crown block rail (36), the performance of the sliding crown block one (41) and the sliding crown block two (42) is inspected, and after the inspection is qualified, the sliding crown block two (42) is used to lift the heavy weight block (47).

6. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 1, characterized in that, In the fourth step, one end of the welding operation platform (51) is supported in the limiting channel steel (13) on the surface of the steel cantilever (12) through the mobile pulley (55), and the other end is hung below the steel cantilever (12) through the temporary steel wire rope (57); the sliding trolley one (41) is controlled to slide to the outside of the steel box girder (11), and the sliding trolley two (42) with the weight block (47) is moved to the other side to balance the load of the steel cantilever (12); after the sliding trolley one (41) slides to the specified position, the steel cantilever (12) segment is lowered, and when the top surface of the steel cantilever (12) is at a certain height from the top surface of the steel box girder (11), the telescopic sleeve (46) on the sliding trolley one (41) is locked by using the locking pin shaft (48), and then the steel cantilever (12) is lowered to be flush with the steel box girder (11), and the mobile pulley (55) at the other end of the welding operation platform (51) is supported in the limiting channel steel (13) on the side of the steel box girder (11).

7. The method of using the device for pre-assembling and hoisting construction of a large cantilever flange steel box girder according to claim 6, characterized in that, In the fifth step, the temporary steel wire rope (57) between the welding operation platform (51) and the steel cantilever (12) is removed, and then the welding operation of the steel cantilever (12) is carried out, the weld at the bottom of the steel cantilever (12) is carried out relying on the welding operation platform (51), the operator enters the welding operation platform (51) through the ladder (53), and the welding operation platform (51) moves along the surface of the steel cantilever (12) and the limiting channel steel (13) on the side of the steel box girder (11).

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