Method for switching supporting legs during construction of single-girder bridge girder erection machine

Abstract

The invention provides a supporting leg switching method during construction of a single-girder bridge girder erection machine, which comprises the following steps of: firstly, ensuring that a middle supporting leg is completely suspended on a lower flange plate of a girder or a guide beam, and then enabling two reverse hanging wheel groups on two sides of the middle supporting leg to uniformly bear gravity; the middle supporting leg automatically travels to the front of the bending position through the reverse hanging wheel set, the hoisting crown block also travels to the position over the middle supporting leg along the main beam and the cantilever beam, and two lifting hooks of the hoisting crown block are lowered and connected to a middle supporting leg cross beam through a lifting appliance; the middle supporting leg is lifted by the lifting crown block to travel on the cantilever beam, so that the middle supporting leg crosses the gap at the bending position and moves to the guide beam or the main beam, the reverse hanging wheel set of the middle supporting leg is located on the lower flange plate of the guide beam or the main beam, then the lifting crown block releases the hook downwards, the middle supporting leg is hung on the lower flange plate of the guide beam or the main beam, and leg toppling is completed. On the premise that normal bending of the main beam and the front guide beam is met, leg reversing can be achieved through the device, the construction difficulty is lowered, and the construction process is simplified.

Description

Technical Field

[0001] This invention provides a method for switching outriggers of a segmented bridge erecting machine, specifically a method for switching outriggers during the construction of a single main beam bridge erecting machine, belonging to the field of bridge construction technology. Background Technology

[0002] Most segmental bridge erecting machines adopt a double-main-girder structure. The construction technology of double-girder segmental bridge erecting machines is relatively mature. In the construction of viaducts with small curves, the bending of the double main beams and front and rear guide beams enables construction with small curve turning radii. However, in situations where pier space is narrow and the single-line beam width is small, single-girder bridge erecting machines are more suitable. Because single-girder segmental bridge erecting machines need to meet the requirements of small curve construction, the main beam and front guide beam also need to be bent. However, in the crossing section, single-girder bridge erecting machines cannot use the crossing-leg-reversing method (which involves alternating the use of legs #2 and #3) to switch the middle leg from the main beam and guide beam (i.e., leg reversing) as with double-girder bridge erecting machines. This is because double-girder segmental bridge erecting machines have two main beams, allowing for the crossing-leg-reversing process; however, single-girder bridge erecting machines only have one main beam, so leg reversing can only be done sequentially, not crossing. Furthermore, due to the existence of the bending structure between the main beam and the guide beam, the track is discontinuous. Therefore, when moving the middle support leg through the hole, it is quite difficult to move it from the main beam to the guide beam or from the guide beam back to the main beam. It requires the assistance of external devices to complete, which is time-consuming and labor-intensive. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for switching outriggers during the construction of a single main beam bridge erecting machine. This method overcomes the shortcomings of the prior art and, under the premise of ensuring normal bending of the main beam and the leading beam, can achieve outrigger switching using its own device. It has the advantages of simple structure, reduced construction difficulty, and simplified construction process.

[0004] The technical solution adopted to achieve the above-mentioned objectives of this invention is as follows:

[0005] A method for switching outriggers during the construction of a single main girder bridge erecting machine includes the following steps:

[0006] (1) Install a cantilever beam above the hinge joint between the guide beam and the main beam. The cross section of the cantilever beam is in the shape of a door. The top of the cantilever beam is flush with the top of the main beam and a crane track is installed on the cantilever beam. The crane track on the cantilever beam and the crane track on the main beam are continuously installed for the crane to travel. The cross section of the guide beam is set to a triangular structure. The bottom of the guide beam is flush with the bottom of the main beam and a lower flange plate is installed at the bottom of the guide beam. The position of the guide beam when it is bent does not interfere with the position of the cantilever beam.

[0007] (2) Retract the column of the middle support leg or retract the unloading cylinder below to ensure that the middle support leg is completely suspended on the lower flange of the main beam or guide beam. Then, the horizontal movement cylinder of the middle support leg is activated to adjust the center of gravity of the middle support leg trolley and the components below the reverse hook of the middle support leg beam to the middle support leg trolley directly below, so that the two reverse hanging wheel sets on both sides of the middle support leg bear the weight evenly.

[0008] (3) The middle support leg travels to the front of the bend position via the reverse wheel set, and at the same time the crane travels along the main beam and cantilever beam to the top of the middle support leg. The two hooks of the crane are lowered and connected to the crossbeam of the middle support leg through the lifting device.

[0009] (4) The crane lifts the middle outrigger, so that the weight of the middle outrigger is transferred from the anti-roller assembly to the spreader, and the anti-roller assembly is released.

[0010] (5) The crane hoists the middle outrigger and moves it on the cantilever beam, so that the middle outrigger passes over the gap at the bend and moves to the guide beam or main beam, and the reverse hanging wheel group of the middle outrigger is located on the lower flange plate of the guide beam or main beam. Then the crane releases the hook, so that the middle outrigger is suspended on the lower flange plate of the guide beam or main beam, and the leg reversing is completed.

[0011] Furthermore, the crane described in step (5) is equipped with a rotation and lateral movement functional unit. When there is a bending angle between the main beam and the guide beam, the crane lifts the middle support leg and adjusts the position of the middle support leg by rotation and lateral movement, so that the reverse wheel group of the middle support leg is adjusted to the lower flange plate of the guide beam or the main beam.

[0012] Furthermore, the crane's frame, from bottom to top, includes a lower frame, a middle frame, and an upper frame. A transverse track is installed on the crossbeam of the lower frame, and the middle frame is mounted on the transverse track of the lower frame. A transverse hydraulic cylinder is installed between the middle frame and the lower frame, which pushes and pulls the middle frame to move laterally left and right on the crossbeam of the lower frame. A rotating track is installed above the middle frame, and a positioning hinge is installed in the middle of the middle frame. The upper frame is mounted on the rotating track of the middle frame and is rotatably connected to the middle frame through the positioning hinge. A rotating hydraulic cylinder is installed between the upper frame and the middle frame, which pushes and pulls the upper frame to rotate on the rotating track of the middle frame.

[0013] Furthermore, in step (4), when the angle between the main beam and the guide beam is greater than a certain angle, after the reverse wheel assembly is loosened, the locking nut of the fixed pin in the reverse wheel assembly needs to be loosened, and then the reverse wheel assembly is slid outward a certain distance to adjust the gap between the reverse wheel assembly and the lower flange plate of the main beam or guide beam; after the middle support leg passes through the gap at the bend, the locking nut of the fixed pin in the reverse wheel assembly is tightened again.

[0014] Furthermore, in step (1), the front end of the cantilever beam is provided with an upward-protruding vehicle stop to restrict the travel position of the crane.

[0015] Furthermore, the lower frame is a double-beam frame structure, on which two transverse hydraulic cylinders are installed, and the two transverse hydraulic cylinders are respectively installed on two crossbeams; the lower part of the middle frame is equipped with an MGB sliding plate at the part that contacts the transverse track, and the transverse distance of the middle frame on the lower frame is ±500mm.

[0016] Furthermore, two rotary cylinders are provided, and the two rotary cylinders are installed on the same side of the upper frame. An MGB slide plate is provided at the lower part of the upper frame that contacts the rotary track. The horizontal rotation angle of the upper frame on the middle frame is ±20°.

[0017] Furthermore, in step (1), two horizontally distributed hinge seats are provided at the end face of the guide beam connected to the main beam, and two horizontally distributed hinge seats are provided at the front and rear ends of the main beam, and the main beam and the two guide beams are hinged together; four horizontal rotating cylinders are provided at the connection between the guide beam and the main beam, and are installed in pairs at both ends of the main beam. The two horizontal rotating cylinders are symmetrically arranged on the left and right, and the two ends of the horizontal rotating cylinders are connected to the main beam and the guide beam respectively through ear plates. The bending angle of the main beam and the guide beam is controlled by the extension and retraction of the horizontal rotating cylinders.

[0018] Furthermore, in step (1), mechanical locks for fixing the angle between the guide beam and the main beam are provided at the connection between the guide beam and the main beam. The two ends of the mechanical locks are connected to the guide beam and the main beam respectively through ear plates. There are four mechanical locks, which are installed in pairs at both ends of the main beam. The two mechanical locks are symmetrically arranged on the left and right and located above the horizontal rotation cylinder.

[0019] Furthermore, in step (1), the cantilever beam is a rectangular truss structure consisting of two web plates on the left and right sides connected by a middle channel steel. The root of the cantilever beam is bolted to the web plate of the main beam with a joint plate, and the overhead crane track is set above the two web plates on the left and right sides of the cantilever beam.

[0020] Compared with existing technologies, the bendable single-beam structure of the bridge erecting machine provided by this invention has the following advantages: 1. In order to achieve leg reversal, this patent creatively proposes a cantilever beam structure. The cross-section of the cantilever beam is U-shaped, the top of the cantilever beam is flush with the top of the main beam, and a track is provided on the cantilever beam. The track on the cantilever beam is continuously arranged with the track on the main beam for the crane to travel. With the above structure, when reversing the legs, the crane can lift the middle support leg and transfer it from the main beam to the track of the guide beam to bypass the bend at the connection between the two, thereby achieving leg reversal without the aid of external devices.

[0021] 2. In this patent, due to the presence of the cantilever beam, in order to prevent the cantilever beam from affecting the normal bending between the guide beam and the main beam, the cross-section of the guide beam is innovatively set as a triangular structure, while the cross-section of the cantilever beam is in the shape of a gate. This ensures that the position of the cantilever beam and the position of the guide beam during bending do not interfere with each other, so as to meet the normal bending requirements. Attached Figure Description

[0022] Figure 1 This is an overall schematic diagram of the single beam structure of the bendable bridge erecting machine in this invention;

[0023] Figure 2 This is a top view of a single-beam structure in a bent state;

[0024] Figure 3 A schematic diagram of the overall structure of the main beam;

[0025] Figure 4 Top view of the overall structure of the main beam;

[0026] Figure 5 This is a schematic diagram of the overall structure of the guide beam;

[0027] Figure 6 This is a top view of the overall structure of the guide beam;

[0028] Figure 7 This is a side view of the overall structure of the guide beam;

[0029] Figure 8 A structural schematic diagram of the connection between the main beam and the guide beam;

[0030] Figure 9 for Figure 8 Sectional view along axis AA;

[0031] Figure 10 for Figure 8 BB-direction sectional view;

[0032] Figure 11 for Figure 8 CC-direction sectional view;

[0033] Figure 12 for Figure 8 DD section view;

[0034] Figure 13 This is a schematic diagram of the overall structure of the cantilever beam;

[0035] Figure 14 This is a top view of the overall structure of the cantilever beam;

[0036] Figure 15 This is a schematic diagram showing the state after the cantilever beam is connected to the main beam.

[0037] Figure 16 This is a schematic diagram of the overall structure of the overhead crane;

[0038] Figure 17 This is a side view of the overall structure of the overhead crane;

[0039] Figure 18This is a structural schematic diagram of the overhead crane frame;

[0040] Figure 19 This is a top view of the crane frame.

[0041] Figure 20 This is a structural diagram of the lower frame of the overhead crane;

[0042] Figure 21 This is a schematic diagram of the frame structure of a crane.

[0043] Figure 22 This is a structural diagram of the overhead crane's frame;

[0044] Figure 23 The steps of the outrigger replacement method in this invention Figure 1 ;

[0045] Figure 24 The steps of the outrigger replacement method in this invention Figure 2 ;

[0046] Figure 25 The steps of the outrigger replacement method in this invention are as follows. Figure 3 ;

[0047] Figure 26 The steps of the outrigger replacement method in this invention Figure 4 ;

[0048] In the diagram: 1-Main beam, 2-Guide beam, 21-Upper hinge seat, 22-Lower hinge seat, 23-Traveling platform, 3-Cantilever beam, 31-Crane track, 32-Web plate, 33-Channel steel, 34-Stop, 4-Horizontal rotation cylinder, 5-Mechanical lock, 6-Crane, 61-Lower frame, 62-Middle frame, 63-Upper frame, 64-Horizontal movement cylinder, 65-Positioning hinge shaft, 66-Rotating cylinder, 7-Front and middle outriggers, 8-Rear and middle outriggers. Detailed Implementation

[0049] The following is a detailed description of this patent in conjunction with the accompanying drawings.

[0050] The segmented bridge erecting machine used in this embodiment has a bendable single-beam structure that differs from conventional structures. This patent relies on the following structure to achieve the leg-reversing mechanism, the main structure of which is as follows: Figure 1 and Figure 2 As shown, it includes a single main beam 1 and two guide beams 2 connected to the front and rear ends of the main beam 1. The structure of the main beam 1 is as follows: Figure 3 and Figure 4 As shown, a box girder structure is adopted, with mature manufacturing technology and high reusability. The steel box girder has lower flanges on both sides of the lower cover plate and a longitudinal sliding perforated plate in the middle. The lower web has longitudinal beams on both sides for suspending segmental beams, and the upper cover plate has overhead crane tracks. The structure of guide beam 2 is as follows... Figure 5 , Figure 6 and Figure 7 The structure is divided into two parts: a front guide beam and a rear guide beam. The front and rear guide beams have identical structural forms and are symmetrically arranged. A traveling platform 23 is installed on the lower middle plane of each triangular truss for convenient construction. Longitudinal tracks are provided on both sides of the lower part of the guide beam 2, with a longitudinal perforated plate in the middle. The bottom of the guide beam 2 is flush with the bottom of the main beam 1, and tracks are provided at the bottom of the guide beam 2. Two horizontally distributed hinge seats are provided at the end face of the guide beam 2 where it connects to the main beam 1. Correspondingly, two horizontally distributed hinge seats are provided at the front and rear ends of the main beam. The main beam and the two guide beams are hinged together. The two horizontally distributed hinge seats are the upper hinge seat 21 and the lower hinge seat 22, respectively. The upper hinge seat 21 is located at the end of the top beam in the guide beam 2, and the lower hinge seat 22 is located at the middle position of the end of the bottom beam in the guide beam 2. The main beam 1 and the guide beam 2 can be bent horizontally at a certain angle, with the horizontal bending angle between the main beam and the cantilever beam ≤ ±12°.

[0051] A horizontal rotation cylinder 4 is installed at the connection between the guide beam 2 and the main beam 1, such as... Figure 8-12 As shown, the two ends of the horizontal rotating cylinder 4 are connected to the main beam 1 and the guide beam 2 respectively. The bending angle of the main beam 1 and the guide beam 2 is controlled by the extension and retraction of the horizontal rotating cylinder 4. Four horizontal rotating cylinders 4 are provided, installed in pairs at both ends of the main beam. Two horizontal rotating cylinders are symmetrically arranged on the left and right sides, located at the bottom sides of the connection between the guide beam and the main beam. The two ends of the horizontal rotating cylinders are connected to the guide beam and the main beam respectively through ear plates. Mechanical locks 5 are provided at the connection between the guide beam 2 and the main beam 1 to fix the angle between the guide beam and the main beam. The two ends of the mechanical locks 5 are connected to the guide beam and the main beam respectively through ear plates. Four mechanical locks 5 are provided, installed in pairs at both ends of the main beam. Two mechanical locks are symmetrically arranged on the left and right sides, located above the horizontal rotating cylinders. When it is necessary to adjust the bending angle, the mechanical locks are opened; after the angle adjustment is completed, the mechanical locks are locked in time.

[0052] Cantilever beams 3 are also provided at both ends of the main beam 1. The structure of the cantilever beams is as follows: Figure 13 , Figure 14 and Figure 15 As shown, a single cantilever beam 3 has a total length of 4500mm. Its single weight is approximately 3t, and the total weight of the front and rear cantilever beams is approximately 6t. The cantilever beam 3 has a U-shaped cross-section. The top of the cantilever beam 3 is flush with the top of the main beam 1, and a crane track 31 is installed on the cantilever beam. The crane track 31 on the cantilever beam 3 is continuously connected to the crane track on the main beam 1 for crane movement. The cantilever beam 3 is located above the end of the guide beam 2, and its position does not interfere with the bending position of the guide beam 2. The cantilever beam 3 is a rectangular truss structure composed of two web plates 32 connected by a central channel steel 33. The root of the cantilever beam 3 is bolted to the web plate of the main beam 1 using a joint plate. The crane track 31 is located above the two web plates 32 of the cantilever beam. A raised stop 34 is provided at the front end of the cantilever beam 3.

[0053] The segmented bridge erecting machine used in this embodiment, while having rotation and lateral movement functional units in its overhead crane, does not achieve the aforementioned objective. The structure of the overhead crane provided in this embodiment is as follows: Figure 16 and Figure 17 As shown. The main improvement of the overhead crane lies in the frame, the specific structure of which is as follows: Figure 18-22 As shown, the crane frame consists of a lower frame 61, a middle frame 62, and an upper frame 63 from bottom to top. A transverse track is provided on the crossbeam of the lower frame 61. The middle frame 62 is installed on the transverse track of the lower frame. A transverse hydraulic cylinder 64 is provided between the middle frame and the lower frame. The transverse hydraulic cylinder pushes and pulls the middle frame to move laterally left and right on the crossbeam of the lower frame. A rotating track is provided above the middle frame 62. A positioning hinge shaft 65 is provided in the middle of the middle frame. The upper frame 63 is installed on the rotating track of the middle frame and is rotatably connected to the middle frame through the positioning hinge shaft. A rotating hydraulic cylinder 66 is provided between the upper frame and the middle frame. The rotating hydraulic cylinder 66 pushes and pulls the upper frame 63 to rotate on the rotating track of the middle frame 62. The lower frame 61 is a double-beam frame structure, on which two lateral movement cylinders 64 are installed, each mounted on one of the two crossbeams. An MGB sliding plate is installed at the lower part of the middle frame where it contacts the lateral movement track. The lateral movement distance of the middle frame on the lower frame is ±500mm. Two rotary cylinders 66 are provided, installed on the same side of the upper frame 63. An MGB sliding plate is installed at the lower part of the upper frame where it contacts the rotary track. The horizontal rotation angle of the upper frame on the middle frame is ±20°.

[0054] Based on the above structural foundation, the steps for reversing the support legs in this embodiment are as follows: First, retract the column of the middle support leg or retract the unloading cylinder below it to ensure that the middle support leg is completely suspended on the lower flange plate of the main beam 1 or guide beam 2. Then, the lateral movement cylinder of the middle support leg is activated to adjust the center of gravity of the middle support leg trolley and the components below the reverse hook of the middle support leg crossbeam to be directly below the middle support leg trolley, so that the two reverse hanging wheel sets on both sides of the middle support leg bear the weight evenly. Next, the middle support leg is moved to the front of the bending position by the reverse hanging wheel sets, while the overhead crane also moves along the main beam 1 and the cantilever beam 3 to the top of the middle support leg. First, the two hooks of the overhead crane 6 are lowered and connected to the crossbeam of the middle support leg via a lifting device. Then, the overhead crane is used to lift the middle support leg, transferring the weight load of the middle support leg from the reverse roller assembly to the lifting device, thus loosening the reverse roller assembly. When the angle between the main beam and the guide beam is greater than a certain angle, after the reverse roller assembly is loosened, the locking nut of the fixing pin in the reverse roller assembly needs to be loosened. Then, the reverse roller assembly is slid outward a certain distance to adjust the gap between the reverse roller assembly and the lower flange plate of the main beam or guide beam. After the middle support leg passes through the gap at the bend, the locking nut of the fixing pin in the reverse roller assembly is tightened again. Finally, the overhead crane, carrying the middle outrigger, travels along the cantilever beam, allowing the middle outrigger to cross the gap at the bend and move onto the guide beam or main beam. The inverted wheel assembly of the middle outrigger is positioned on the lower flange of the guide beam or main beam. Then, the overhead crane 6 lowers its hook, suspending the middle outrigger on the lower flange of the guide beam or main beam, completing the outrigger reversal. When there is a bend between the main beam 1 and the guide beam 2, the overhead crane 6, carrying the middle outrigger, adjusts its position by rotating and lateral movement, thereby adjusting the inverted wheel assembly of the middle outrigger to the lower flange of the guide beam or main beam.

[0055] In the specific construction phase, the segmental bridge erecting machine has two middle legs, namely the front middle leg 7 and the rear middle leg 8. When the bridge erecting machine passes through the span, it is necessary to reverse the legs, that is, to reverse the rear middle leg from the rear guide beam to the main beam, and to reverse the front middle leg from the main beam to the front guide beam. The specific construction process is as follows: Figure 23-26 As shown. The bridge erecting machine only begins to switch the middle support leg after the No. 1 support leg (i.e., the front auxiliary support leg) is supported on the foremost pier. First, the No. 4 support leg (i.e., the rear auxiliary support leg) bears the load, releasing the No. 3 support leg (i.e., the rear middle support leg 8). After the No. 3 support leg is switched over by the crane, it travels along the main beam to the rear of the No. 2 support leg (i.e., the front middle support leg 7) and supports it, thus releasing the load on the No. 2 support leg. The No. 2 support leg then moves forward to the pier at the position of the No. 1 support leg and bears the load. At this point, the load on the No. 1 support leg can be released, and the No. 1 support leg can be retracted and lifted into the air. Then, the entire main beam moves forward until the bridge erecting machine completes the main beam crossing the span.

Claims

1. A method for switching outriggers during construction of a single main girder bridge erecting machine, characterized in that... Includes the following steps: (1) Install a cantilever beam above the hinge joint between the guide beam and the main beam. The cross section of the cantilever beam is in the shape of a door. The top of the cantilever beam is flush with the top of the main beam and a crane track is installed on the cantilever beam. The crane track on the cantilever beam and the crane track on the main beam are continuously installed for the crane to travel. The cross section of the guide beam is set to a triangular structure. The bottom of the guide beam is flush with the bottom of the main beam and a lower flange plate is installed at the bottom of the guide beam. The position of the guide beam when it is bent does not interfere with the position of the cantilever beam. (2) Retract the column of the middle support leg or retract the unloading cylinder below to ensure that the middle support leg is completely suspended on the lower flange of the main beam or guide beam. Then, the horizontal movement cylinder of the middle support leg is activated to adjust the center of gravity of the middle support leg trolley and the components below the reverse hook of the middle support leg beam to the middle support leg trolley directly below, so that the two reverse hanging wheel sets on both sides of the middle support leg bear the weight evenly. (3) The middle support leg travels to the front of the bend position via the reverse wheel set, and at the same time the crane travels along the main beam and cantilever beam to the top of the middle support leg. The two hooks of the crane are lowered and connected to the crossbeam of the middle support leg through the lifting device. (4) The crane lifts the middle outrigger, so that the weight of the middle outrigger is transferred from the anti-roller assembly to the spreader, and the anti-roller assembly is released. (5) The crane hoists the middle outrigger and moves it on the cantilever beam, so that the middle outrigger passes over the gap at the bend and moves to the guide beam or main beam, and the reverse hanging wheel group of the middle outrigger is located on the lower flange plate of the guide beam or main beam. Then the crane releases the hook, so that the middle outrigger is suspended on the lower flange plate of the guide beam or main beam, and the leg reversing is completed.

2. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 1, characterized in that: The crane described in step (5) is equipped with a rotation and lateral movement function unit. When there is a bending angle between the main beam and the guide beam, the crane lifts the middle support leg and adjusts the position of the middle support leg by rotation and lateral movement, so that the reverse wheel group of the middle support leg is adjusted to the lower flange plate of the guide beam or the main beam.

3. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 2, characterized in that: The crane frame consists of a lower frame, a middle frame, and an upper frame from bottom to top. A lateral moving track is installed on the crossbeam of the lower frame. The middle frame is mounted on the lateral moving track of the lower frame. A lateral moving cylinder is installed between the middle frame and the lower frame. The lateral moving cylinder pushes and pulls the middle frame to move laterally left and right on the crossbeam of the lower frame. A rotating track is installed above the middle frame. A positioning hinge is installed in the middle of the middle frame. The upper frame is mounted on the rotating track of the middle frame and is rotatably connected to the middle frame through the positioning hinge. A rotating cylinder is installed between the upper frame and the middle frame. The rotating cylinder pushes and pulls the upper frame to rotate on the rotating track of the middle frame.

4. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 1, characterized in that: In step (4), when the angle between the main beam and the guide beam is greater than a certain angle, after the reverse wheel assembly is loosened, the locking nut of the fixed pin in the reverse wheel assembly needs to be loosened. Then, the reverse wheel assembly is slid outward a certain distance to adjust the gap between the reverse wheel assembly and the lower flange plate of the main beam or guide beam. After the middle support leg passes through the gap at the bend, the locking nut of the fixed pin in the reverse wheel assembly is tightened again.

5. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 1, characterized in that: In step (1), the front end of the cantilever beam is equipped with an upward-protruding vehicle stop to restrict the travel position of the crane.

6. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 3, characterized in that: The lower frame is a double-beam frame structure with two lateral movement cylinders installed on it. The two lateral movement cylinders are respectively installed on two crossbeams. The lower part of the middle frame is equipped with an MGB sliding plate at the part that contacts the lateral movement track. The lateral movement distance of the middle frame on the upper left and right of the lower frame is ±500mm.

7. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 3, characterized in that: Two rotary cylinders are provided, and the two rotary cylinders are installed on the same side of the upper frame. The lower part of the upper frame that contacts the rotary track is provided with an MGB slide plate. The horizontal rotation angle of the upper frame on the middle frame is ±20°.

8. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 1, characterized in that: In step (1), two horizontally distributed hinge seats are provided at the end face of the guide beam connected to the main beam. Two horizontally distributed hinge seats are provided at the front and rear ends of the main beam. The main beam and the two guide beams are hinged together. Four horizontal rotating cylinders are provided at the connection between the guide beam and the main beam. They are installed in pairs at both ends of the main beam. The two horizontal rotating cylinders are symmetrically arranged on the left and right. The two ends of the horizontal rotating cylinders are connected to the main beam and the guide beam respectively through ear plates. The bending angle of the main beam and the guide beam is controlled by the extension and retraction of the horizontal rotating cylinders.

9. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 8, characterized in that: In step (1), mechanical locks for fixing the angle between the guide beam and the main beam are provided at the connection between the guide beam and the main beam. The two ends of the mechanical locks are connected to the guide beam and the main beam respectively through ear plates. There are four mechanical locks, which are installed in pairs at both ends of the main beam. The two mechanical locks are symmetrically arranged on the left and right and located above the horizontal rotation cylinder.

10. The method for switching outriggers during construction of a single main beam bridge erecting machine according to claim 1, characterized in that: In step (1), the cantilever beam is a rectangular truss structure consisting of two web plates on the left and right sides connected by a channel steel in the middle. The root of the cantilever beam is bolted to the web plate of the main beam with a joint plate. The overhead crane track is set above the two web plates on the left and right sides of the cantilever beam.

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