Method for processing and manufacturing steel box girder

Abstract

Disclosed is a method for processing and manufacturing a steel box girder, the method comprising the following steps: decomposing a steel box girder into different plate units for separate processing; installing an assembly jig frame on a tooling jig frame, fabricating a top plate unit on the assembly jig frame, and upon completion of fabrication, moving the top plate unit to a position directly below the tooling jig frame; fabricating a bottom plate unit on the tooling jig frame, and laying diaphragm units and web units on the bottom plate unit; welding the bottom plate unit, the diaphragm units, and the web units to form a first box body having an opening on a top surface thereof; turning over the tooling jig frame to rotate the first box body such that the opening of the first box body directly faces the top plate unit, driving the tooling jig frame to move downward such that the first box body presses against the top plate unit, and welding the first box body and the top plate unit to form a second box body; and assembling cross-bracing and cantilever units onto the second box body to form a steel box girder. In the present invention, the steel box girder is fabricated as different plate units followed by overall segmental assembly, thereby improving control over the fabrication precision of the plate units and achieving alignment control and processing precision of the steel box girder.

Description

Steel box girder processing and manufacturing method TECHNICAL FIELD

[0001] The present application relates to the bridge processing technical field, more particularly, the present application relates to a steel box girder processing and manufacturing method. BACKGROUND

[0002] At present, the steel for highway bridge construction in China is remarkable, especially the steel structure box type bridge, which has the characteristics of strong crossing ability, suitable for factory assembly and manufacturing, convenient transportation, fast installation construction speed, easy repair and replacement, large torsional stiffness, good overall performance, small environmental impact during construction, etc., and is most widely used. At present, steel box girder is more and more used in highway bridges in China, and how to control the spatial linear and overall geometric size of the steel box girder during factory manufacturing becomes very tricky.

[0003] Therefore, designing a curved variable cross-section steel box girder processing and manufacturing method to effectively control the spatial linear and overall geometric size of the steel box girder during factory manufacturing has become a technical problem to be solved by the technical personnel in the technical field. SUMMARY

[0004] Another object of the present application is to provide a steel box girder processing and manufacturing method, which decomposes the steel box girder into different plate units for processing, and then performs overall assembly of the segments, so that the manufacturing precision of the plate units can be better controlled, and the linear control and processing precision of the steel box girder can be realized.

[0005] In order to achieve these objects and other advantages according to the present application, a steel box girder processing and manufacturing method is provided, comprising the following steps:

[0006] S1, the steel box girder is decomposed into different plate units for processing, and the plate units include top plate unit, bottom plate unit, web plate unit, partition plate unit, cross link and cantilever unit;

[0007] S2, installing an assembly jig on a tool jig, manufacturing the top plate unit on the assembly jig, and moving the top plate unit to be located directly below the tool jig after manufacturing is completed;

[0008] S3, removing the assembly jig, manufacturing the bottom plate unit on the tool jig, and laying the partition plate unit and the web plate unit on the bottom plate unit after manufacturing is completed; the bottom plate unit, the partition plate unit and the web plate unit are welded to form a first box body with an opening on the top surface;

[0009] S4, turning over the tool jig to drive the first box body to rotate to the position where the opening of the first box body faces the top plate unit, driving the tool jig to move downward to press the top plate unit at the opening of the first box body, and welding the first box body and the top plate unit to form a second box body;

[0010] S5, again turn over the jig jig frame to the top surface of the top plate unit upward, the transverse connection and cantilever unit assembled to the second box, on the second box assembly top plate shear key to form a steel box girder.

[0011] Preferably, the jig jig frame includes a base horizontally arranged, two supports are symmetrically arranged on the base, a circular side plate is rotatably arranged on any of the supports, an installation plate is arranged on the inner side wall of any of the circular side plates, a jig platform is fixedly arranged between the two installation plates, the jig platform is a frame structure formed by welding a profile steel, the linear type of the top surface of the jig platform is consistent with the linear type of the bottom plate of the steel box girder, the jig platform is used for placing the assembly jig or the first box, a pressing device is arranged on any of the installation plates, and the pressing device is used for pressing the assembly jig or the first box.

[0012] The assembly jig is a frame structure formed by welding a profile steel, and after the assembly jig is erected on the jig platform, the linear type of the top surface of the assembly jig is consistent with the linear type of the top plate of the steel box girder.

[0013] Preferably, the pressing device includes a plurality of first hydraulic cylinders, which are arranged at intervals along the width direction of the base, the fixed end of any first hydraulic cylinder is hingedly connected with the corresponding installation plate, the free end is hingedly connected with the same pressing plate, and the extension direction of the free end of the hydraulic cylinder is arranged obliquely downward.

[0014] Preferably, any of the circular side plates is driven to rotate by a driving assembly, the driving assembly includes a rack arranged on the circumferential outer side of the circular side plate, and a motor mounted on the base, the output shaft of the motor is connected with the rack in meshing connection through a gear.

[0015] Preferably, an annular slide rail is arranged on the side wall of the side of the support facing the gear, a sliding device is arranged on the side of the gear facing the support, and the sliding device is arranged on the annular slide rail while the gear is driven to rotate by the motor.

[0016] Preferably, a guide rail is arranged on the inner side wall of any of the circular side plates, the guide rail is arranged along the height direction of the base, the installation plate is slidably arranged on the guide rail, a bottom plate is fixedly arranged on the inner side wall of the bottom of the circular side plate, a plurality of second hydraulic cylinders are arranged on the bottom plate along the width direction of the base, the free end of the second hydraulic cylinder is fixedly connected with the bottom of the installation plate vertically upward, and the installation plate is driven to move vertically on the guide rail by the second hydraulic cylinder.

[0017] Preferably, an inclination sensor is installed on the tooling platform to detect the inclination angle of the working platform; a ring-shaped groove is formed in the inner bottom surface of the ring-shaped slide rail; the sliding device comprises a plurality of sliders which are arranged at intervals along the circumference of the gear, one end of any slider is fixedly connected with the side wall of the gear, and the other end is slidably connected with the ring-shaped slide rail, a through groove is formed in the interior of the slider along its axial direction, the through groove penetrates through the end of the slider close to the ring-shaped slide rail, and a micro electric push rod is installed in the through groove;

[0018] The inclination sensor, the micro electric push rod and the motor are connected with an electronic control unit, when the electronic control unit monitors that the inclination angle of the working platform measured by the inclination sensor reaches a specified angle, the electronic control unit controls the motor to stop working while driving the free end of the micro electric push rod to extend out of the through groove and be clamped in the ring-shaped groove.

[0019] Preferably, in step S2, when the top plate unit is manufactured, automatic equipment is used for symmetrical welding of the top plate ribs to control welding deformation, and in the process of welding, the top plate unit is tilted at different angles by the overturning tooling platform to realize welding of different weld positions of the top plate ribs, after welding, the flame correction method is used to correct to the natural state and completely fit the assembly jig frame, and then the top plate unit is moved to the base.

[0020] Preferably, in step S3, when the bottom plate unit is manufactured, automatic equipment is used for symmetrical welding of the bottom plate ribs to control welding deformation, and in the process of welding, the bottom plate unit is tilted at different angles by the overturning tooling platform to realize welding of different weld positions of the bottom plate ribs, after welding, the flame correction method is used to correct to the natural state and completely fit the tooling platform.

[0021] The present application at least comprises the following beneficial effects: the present application can better control the manufacturing precision of the plate unit by adopting different plate units to process the steel box girder and then performing the overall assembly of the segments, realizes the linear control and processing precision of the steel box girder; when manufacturing the top plate unit and the bottom plate unit, the welding operation on different welding seam positions of the plate rib is realized by utilizing the overturning function of the tooling jig frame, compared with the method that after welding the inner side welding seam in the traditional plate rib welding construction, the plate material needs to be transferred to the reverse deformation jig frame to complete the welding of the outer side welding seam, the step of hoisting and transferring the plate material is saved, the hoisting operation is reduced, the construction efficiency is improved, and the deformation of the plate material in the hoisting process is also avoided; when welding the first box body and the top plate unit, the first box body is pressed on the top plate unit by utilizing the overturning and vertical movement functions of the tooling jig frame, the fitting degree between the first box body and the top plate unit is ensured, compared with the method that the top plate is fitted with the web and the cross web by adopting the box pressing to assist the positioning and fixation of the top plate unit in the traditional top plate unit welding, the top plate welding and pressing process of the present application are performed synchronously, the process of the box pressing to assist the fixation of the top plate is saved, and the construction efficiency is improved.

[0022] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 is a front view structural schematic diagram of the tooling jig frame of the present application;

[0024] Fig. 2 is a structural schematic diagram of the ring-shaped sliding rail of the present application;

[0025] Fig. 3 is a structural schematic diagram of the sliding device of the present application;

[0026] The description of the drawings of the present application is as follows: 1, base, 2, support, 3, circular side plate, 4, mounting plate, 5, tooling platform, 6, first hydraulic oil cylinder, 7, pressing plate, 8, rack, 9, motor, 10, gear, 11, ring-shaped sliding rail, 12, ring-shaped groove, 13, second hydraulic oil cylinder, 14, sliding block, 15, micro electric push rod, 16, mounting plate. DETAILED DESCRIPTION

[0027] The present application will be further described in detail below with reference to the drawings, so that those skilled in the art can implement the present application according to the description.

[0028] It should be noted that in the description of the present application, the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0029] Embodiment one

[0030] As shown in FIGS. 1-3, the present application provides a steel box girder processing and manufacturing method, comprising the following steps:

[0031] S1, according to the design drawing, the steel box girder is divided into different plate units for processing respectively, the plate units include top plate unit, bottom plate unit, web plate unit, partition plate unit, transverse connection and cantilever unit; the web plate unit is completed on the web plate tooling, and the partition plate unit is completed on the partition plate tooling;

[0032] S2, a assembling jig frame is installed on the tooling jig frame, the tooling jig frame includes a base 1 which is horizontally arranged, two supports 2 are symmetrically arranged on the base 1, and the base 1 and the support 2 are used for supporting the tooling jig frame; a circular side plate 3 is rotatably arranged on any support 2, an installation plate 4 is arranged on the inner side wall of any circular side plate 3, a tooling platform 5 is fixedly arranged between the two installation plates 4, and the tooling platform 5 is driven to rotate by rotating the circular side plate 3; the tooling platform 5 is a frame structure formed by welding section steels, the linear type of the top surface of the tooling platform 5 is consistent with the linear type of the bottom plate of the steel box girder, and the assembling jig frame is also a frame structure formed by welding section steels, and the linear type of the top surface of the assembling jig frame is consistent with the linear type of the top plate of the steel box girder after the assembling jig frame is erected on the tooling platform 5;

[0033] S3, the roof unit is laid on the assembling jig frame, any mounting plate 4 is provided with a pressing device, the pressing device comprises a plurality of first hydraulic cylinders 6, which are arranged at intervals along the width direction of the base 1, the fixed end of any first hydraulic cylinder 6 is hinged with the corresponding mounting plate 4, the free end is hinged with the same pressing plate 7, the extension direction of the free end of the hydraulic cylinder is arranged obliquely downward; after the roof unit is laid on the tool platform 5, the free ends of the plurality of first hydraulic cylinders 6 are driven to extend synchronously to drive the pressing plate 7 to press the roof unit and the assembling jig frame, then the roof rib welding process is carried out, automatic equipment is used for symmetrical welding during roof rib welding to control welding deformation, and in the process of welding, the tool platform 5 is turned over by the rotating mode of the circular side plate 3 to drive the roof unit to tilt at different angles to realize welding of different weld positions of the roof rib, after welding is completed, the flame correction method is used to correct to the natural state to completely adhere to the assembling jig frame, the free ends of the plurality of first hydraulic cylinders 6 are driven to retract synchronously to drive the pressing plate 7 away from the roof unit, and the roof unit is lifted and moved to the base 1;

[0034] Wherein, the circular side plate 3 is driven to rotate by a driving assembly, the driving assembly comprises a rack 8 arranged on the circumferential outer side of the circular side plate 3; a motor 9 mounted on the base 1, the output shaft of the motor 9 is connected with the rack 8 through a gear 10, specifically: the gear 10 is driven to rotate by controlling the motor 9 to work, the gear 10 drives the rack 8 to rotate, thereby driving the circular side plate 3 fixedly connected with the rack 8 to rotate, the circular side plate 3 drives the tool platform 5 connected with it through the mounting plate 4 to rotate, finally drives the assembling jig frame and the roof unit on the tool platform 5 to tilt at different angles, realizes the welding operation of different weld positions of the roof rib;

[0035] S4, remove the assembling jig frame, make the bottom plate unit on the tool platform 5, when making, first lay the bottom plate unit on the tool jig frame, press the bottom plate unit by the pressing device, then weld the bottom plate rib on the bottom plate unit, automatic equipment is used for symmetrical welding during bottom plate rib welding to control welding deformation, and in the process of welding, the circular side plate 3 is driven to rotate by the driving assembly to turn over the tool platform 5 to drive the bottom plate unit to tilt at different angles to realize welding of different weld positions of the bottom plate rib, after welding is completed, the flame correction method is used to correct to the natural state to completely adhere to the tool platform 5; lay the partition plate unit and the web plate unit on the bottom plate unit; weld the bottom plate unit, the partition plate unit and the web plate unit to form a first box body with an opening on the top surface; the position of the pressing device pressing the bottom plate unit does not affect the welding of the bottom plate rib, the partition plate unit and the web plate unit;

[0036] S5, the driving assembly is used again to drive the tool platform 5 to flip to the opening of the first box body opposite to the top plate unit, the tool platform 5 is driven to move downward, the first box body is driven to move downward to press the top plate unit at the opening of the first box body, and the first box body and the top plate unit are welded to form the second box body; the tool platform 5 is moved downward in the following manner:

[0037] The inner side wall of the circular side plate 3 is provided with a guide rail, the guide rail is arranged along the height direction of the base 1, the mounting plate 4 is slidably arranged on the guide rail, the inner side wall of the bottom of the circular side plate 3 is fixedly provided with a bottom plate 16, a plurality of second hydraulic oil cylinders 13 are arranged on the bottom plate 16 along the width direction of the base 1, and the free ends of the second hydraulic oil cylinders 13 are fixedly connected with the bottom of the mounting plate 4 vertically upward; after the first box body is flipped to the opening thereof opposite to the top plate unit, the free ends of the plurality of second hydraulic oil cylinders 13 are synchronously driven to extend out, and the mounting plate 4 is driven to move downward on the guide rail to press the top plate unit to the first box body.

[0038] S6, the tool platform 5 is flipped again to the top surface of the top plate unit upward, the cross connection and the cantilever unit are assembled to the second box body, and the top plate shear key is assembled to the second box body to form the steel box girder.

[0039] In the above technical solution, the steel box girder is processed by different plate units, and then the segment is assembled, so that the manufacturing precision of the plate unit can be better controlled, the linear control and the manufacturing precision of the steel box girder are realized, and when the top plate unit and the bottom plate unit are manufactured, the turning function of the tool jig frame is utilized to realize welding operation on different welding seam positions of the plate rib. Compared with the method that after the inner side welding seam is welded in the traditional plate rib welding construction, the plate material needs to be transferred to the reverse deformation jig frame to complete the welding of the outer side welding seam, the step of hoisting and transferring the plate material is saved, the hoisting operation is reduced, the construction efficiency is improved, and the deformation of the plate material in the hoisting process is avoided. When the first box body and the top plate unit are welded, the turning and vertical movement functions of the tool jig frame are utilized to press the first box body to the top plate unit, so that the fit degree between the first box body and the top plate unit is guaranteed. Compared with the method that in the traditional welding of the top plate unit, the box is pressed to assist in positioning and fixing the top plate unit, so that the top plate is fitted with the web and the cross wall, the top plate welding and pressing process are simultaneously performed in the present application, the process of pressing the box to assist in fixing the top plate is saved, and the construction efficiency is improved. When the top plate unit is manufactured, the assembly jig frame is installed on the tool jig frame, the space required by the site is reduced, and the site utilization rate is improved.

[0040] In another technical solution, a side wall of the support 2 facing the gear 10 is provided with an annular slide rail 11, and a side of the gear 10 facing the support 2 is provided with a sliding device; the sliding device is slidably arranged on the annular slide rail 11 while the gear 10 is driven to rotate by the electric drive.

[0041] In the technical solution, as shown in Fig. 2, the support 2 is provided with an annular slide rail 11 on the side wall close to the gear 10, the gear 10 is provided with a sliding device on the side wall close to the support 2, the sliding device is matched with the annular slide rail 11, the motor 9 drives the gear 10 to rotate at the same time, the sliding device on the gear 10 moves on the annular slide rail 11, thereby playing a limiting and guiding role for the gear 10, and the stability of the tooling platform 5 during rotation is ensured.

[0042] In another technical solution, the tooling platform 5 is provided with an inclination sensor, the inclination sensor is used for detecting the inclination angle of the working platform, the inner bottom surface of the annular slide rail 11 is provided with an annular groove 12, the sliding device comprises a plurality of sliding blocks 14, the sliding blocks 14 are arranged at intervals along the circumference of the gear 10, one end of any sliding block 14 is fixedly connected with the side wall of the gear 10, the other end is slidably connected with the annular slide rail 11, a through groove is formed in the sliding block 14 along the axial direction, the through groove penetrates the end of the sliding block 14 close to the annular slide rail 11, and a micro electric push rod 15 is installed in the through groove.

[0043] The inclination sensor, the micro electric push rod 15 and the motor 9 are connected with an electronic control unit, when the electronic control unit monitors that the inclination angle of the working platform measured by the inclination sensor reaches a specified angle, the electronic control unit controls the motor 9 to stop working at the same time, and drives the free end of the micro electric push rod 15 to extend out of the through groove and be clamped in the annular groove 12.

[0044] In the technical solution, as shown in Figure 3, the sliding device is composed of a plurality of sliding blocks 14, any sliding block 14 is provided with a micro electric push rod 15, the free end of the micro electric push rod 15 can extend outside the sliding block 14 through a through groove, in the process of rotating the tooling platform 5, the free end of the micro electric push rod 15 is located in the sliding block 14, when the tooling platform 5 is rotated to the required angle, the motor 9 stops rotating, at the same time, the free end of the micro electric push rod 15 is clamped in the annular groove 12 of the annular slide rail 11 through the through groove, thereby limiting the tooling platform 5, so that the tooling platform 5 cannot rotate, ensuring the stability of the tooling platform 5, avoiding shaking during subsequent construction, thereby ensuring the welding effect and ensuring the machining precision of the steel box girder; the tooling platform 5 is provided with an inclination sensor, the inclination sensor, the motor 9 and the micro electric push rod 15 are connected with an electronic control unit, the electronic control unit controls the micro electric push rod 15 and the motor 9 according to the data detected by the inclination sensor, a plurality of inclination target values can be sequentially set in the electronic control unit according to the construction process, after the tooling platform 5 is rotated to the corresponding inclination target value, the electronic control unit controls the free end of the micro electric push rod 15 to extend at the same time as driving the motor 9 to stop working, after the corresponding process operation is completed, the electronic control unit controls the free end of the micro electric push rod 15 to retract into the sliding block 14, and drives the motor 9 to work to drive the tooling platform 5 to rotate to the next inclination target value, thereby realizing semi-automatic operation, improving construction efficiency and reducing the work pressure of the operator.

[0045] Although the embodiments of the present application have been disclosed as above, it is not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the present application, and other modifications can be easily realized by those skilled in the art, therefore, the present application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A method of manufacturing a steel box girder, characterized by, The method comprises the following steps: S1, the steel box girder is divided into different plate units for processing respectively, the plate units including top plate unit, bottom plate unit, web plate unit, partition plate unit, cross link and cantilever unit; S2, the assembling jig frame is installed on the tool jig frame, the top plate unit is made on the assembling jig frame, and the top plate unit is moved to be located directly below the tool jig frame after the top plate unit is made; S3, the assembling jig frame is removed, the bottom plate unit is made on the tool jig frame, the partition plate unit and the web plate unit are laid on the bottom plate unit after the bottom plate unit is made, and the bottom plate unit, the partition plate unit and the web plate unit are welded to form a first box body with an opening on the top surface; S4, the tool jig frame is turned over to drive the first box body to rotate to the position that the opening of the first box body faces the top plate unit, the tool jig frame is driven to move downward to press the top plate unit at the opening of the first box body, and the first box body and the top plate unit are welded to form a second box body; S5, the tool jig frame is turned over again to make the top surface of the top plate unit face upward, the cross link and the cantilever unit are assembled on the second box body, and the top plate shear key is assembled on the second box body to form the steel box girder.

2. The steel box girder fabrication method of claim 1, wherein, The tool jig frame comprises a base horizontally arranged, two supports symmetrically arranged on the base, a circular side plate rotatably arranged on any support, an installation plate arranged on the inner side wall of any circular side plate, a tool platform fixedly arranged between the two installation plates, the tool platform being a frame structure formed by welding profile steels, the linear type of the top surface of the tool platform being consistent with the linear type of the bottom plate of the steel box girder, the tool platform being used for placing the assembling jig frame or the first box body, and a pressing device arranged on any installation plate, the pressing device being used for pressing the assembling jig frame or the first box body. The assembling jig frame is a frame structure formed by welding profile steels, and the linear type of the top surface of the assembling jig frame is consistent with the linear type of the top plate of the steel box girder after the assembling jig frame is arranged on the tool platform.

3. The steel box girder fabrication method of claim 2, wherein, The pressing device comprises a plurality of first hydraulic cylinders, the first hydraulic cylinders are arranged at intervals along the width direction of the base, the fixed end of any first hydraulic cylinder is hingedly connected with the corresponding installation plate, the free end is hingedly connected with the same pressing plate, and the extension direction of the free end of the hydraulic cylinder is arranged obliquely downward.

4. The steel box girder fabrication method of claim 3, wherein, Any circular side plate is driven to rotate by a driving assembly, the driving assembly comprises a rack arranged on the circumferential outer side of the circular side plate, and a motor mounted on the base, the output shaft of the motor being connected with the rack in meshing connection through a gear.

5. The steel box girder fabrication method of claim 4, wherein The side wall of the support facing the gear is provided with an annular slide rail, the side of the gear facing the support is provided with a sliding device, and the sliding device is arranged on the annular slide rail and slides with the gear while the gear is driven to rotate.

6. The steel box girder fabrication method of claim 4, wherein The inner side wall of any circular side plate is provided with a guide rail, the guide rail is arranged along the height direction of the base, the installation plate is arranged on the guide rail in sliding mode, the inner side wall of the bottom of the circular side plate is fixedly provided with a bottom plate, a plurality of second hydraulic cylinders are arranged on the bottom plate along the width direction of the base, the free end of the second hydraulic cylinder is fixedly connected with the bottom of the installation plate in vertical upward mode, and the installation plate is driven to move vertically on the guide rail by the second hydraulic cylinder.

7. The steel box girder fabrication method of claim 3, wherein The tooling platform is provided with an inclination sensor for detecting the inclination angle of the working platform; the inner bottom surface of the annular slide rail is provided with an annular groove; the sliding device comprises a plurality of sliders which are arranged at intervals along the circumference of the gear, one end of any slider is fixedly connected with the side wall of the gear, and the other end is slidably connected with the annular slide rail, a through groove is formed in the interior of the slider along the axial direction thereof, the through groove penetrates through the end of the slider close to the annular slide rail, and a micro electric push rod is arranged in the through groove; The inclination sensor, the micro electric push rod and the motor are connected with an electronic control unit, when the electronic control unit monitors that the inclination angle of the working platform measured by the inclination sensor reaches a specified angle, the electronic control unit controls the motor to stop working, and drives the free end of the micro electric push rod to extend out of the through groove and be clamped in the annular groove.

8. The steel box girder fabrication method of claim 7, wherein, In step S2, when the top plate unit is manufactured, the top plate ribs are symmetrically welded by using automatic equipment to control the welding deformation, and in the welding process, the top plate unit is tilted at different angles by using the turnover tooling platform to realize the welding of different weld positions of the top plate ribs, after the welding is completed, the flame correction method is used to correct to the natural state, and after the top plate unit is completely matched with the assembled jig frame, the top plate unit is moved to the base.

9. The steel box girder fabrication method of claim 7, wherein, In step S3, when the bottom plate unit is manufactured, the bottom plate ribs are symmetrically welded by using automatic equipment to control the welding deformation, and in the welding process, the bottom plate unit is tilted at different angles by using the turnover tooling platform to realize the welding of different weld positions of the bottom plate ribs, after the welding is completed, the flame correction method is used to correct to the natural state, and after the bottom plate unit is completely matched with the tooling platform.

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