A sectional assembly and pre-assembly method of a large box-shaped gantry

Abstract

This invention discloses a segmented welding and pre-assembly method for a large box-type gantry frame. The gantry frame is divided into three large sections connected by flange plates, and each large section is further divided into three smaller sections. Each smaller section is assembled and welded into a U-shaped structure on a flat jig with the non-arched surface as the base. After simultaneous fabrication on multiple work surfaces, the sections are flipped to an installation position with the arched surface facing down. The jig height is adjusted using standard plates of different thicknesses, and the upper wall panels are assembled. The three smaller sections are then butt-welded sequentially to form the large box section. Subsequently, the flange assemblies are bolted together, and the three large sections are horizontally pre-assembled. After the overall dimensions are qualified, the flange plates are welded to the box body. This method reduces the need for dedicated arching jigs and space occupation, improves parallel processing efficiency, and balances the accuracy of arching and overall spatial dimensions.

Description

Technical Field

[0001] This invention relates to the field of steel structure processing technology, and more specifically, to a method for segmented welding and pre-assembly of a large box-type gantry frame. Background Technology

[0002] With the development of urban road renovation and highway ancillary facilities, large-span box-type gantry frames have begun to be used on multi-lane roads. These gantry frames not only have a large span and weight, but also have accessories such as junction boxes and conduits inside the box, thus presenting processing challenges such as large box cross-section, complex internal pipelines, large overall span, and high requirements for overall spatial dimensional accuracy.

[0003] Taking a type of engineering structure as an example, the overall cross-section of a box-type gantry frame is approximately 2m × 2m, the wall panel thickness is 30mm, the span of a single gantry frame is close to 100m, and the overall weight is approximately 200t. Current manufacturing methods typically involve erecting a complete jig with a corresponding camber for the entire component, and then assembling and welding it on this jig. Different components often require separate jigs with different cambers; component fabrication can only begin after the jigs are completed.

[0004] The aforementioned methods require a large area, have a long production cycle, make it difficult to operate multiple work areas simultaneously, and are not conducive to simultaneous construction by multiple workers. Furthermore, the numerous internal components make assembly and welding within the enclosed box inconvenient. Therefore, a processing and manufacturing method that balances production efficiency, site utilization, camber control, and overall dimensional accuracy is needed. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a segmented welding and pre-assembly method for large box-type gantry frames. By using two-stage segmentation, parallel fabrication of U-shaped structures, overall sealing after flipping, and pre-assembly of flange groups, the method reduces the need for dedicated arching jigs and site occupation, shortens the manufacturing cycle, and ensures the arching state and overall spatial dimensions of the gantry frame.

[0006] The present invention adopts the following technical solution:

[0007] A method for segmented welding and pre-assembly of a large box-type gantry frame includes the following steps:

[0008] S1. Divide the gantry frame into two levels, dividing a single gantry frame into three large sections. The three large sections are connected by flange plates, and each large section is divided into three small sections, so that the mating positions of adjacent wall panels are staggered.

[0009] S2. Produce each segment separately, using the non-arched surface of each segment as the assembly bottom surface. Assemble the internal components and box panels on the flat jig and weld them to form a U-shaped structure with one side open, so that multiple segments can be produced simultaneously on multiple flat jig working surfaces.

[0010] S3. Rotate the three smaller U-shaped sections of the same large section by 90° to the same spatial posture as the on-site installation state. Place the three smaller U-shaped sections together on the overall flat frame. Set standard plates of different thicknesses and quantities between the flat frame and the lower wall panel with arching requirements, so that the support surface of the frame is in contact with the lower wall panel at each elevation position. Then assemble the upper wall panel and complete the butt welding between the three smaller sections to form a large closed box structure.

[0011] S4. Complete the production of the three main sections simultaneously according to steps S2 and S3;

[0012] S5. Connect the flange plates at the ends of adjacent large sections with bolts to form a flange group. Temporarily position the flange group at the end of the corresponding large section. Place the three large sections horizontally on the flat jig for overall pre-assembly and spatial dimension measurement. After the measurement results meet the requirements, weld the connection between the flange plate and the corresponding box body, then release the bolt connection of the flange group and disassemble the three large sections.

[0013] Each large section is approximately 35m long, and the three smaller sections are arranged sequentially along the length of the large section.

[0014] Furthermore, in step S1, the butt welds of each wall panel within the same large section are staggered along the length direction.

[0015] Furthermore, before step S2, the wall panel with arching requirements is CNC cut to form an arc-shaped panel with the designed arching value.

[0016] Furthermore, in step S2, longitudinal stiffeners, inner partitions, junction boxes, conduits, lower wall panels, and cover plates are sequentially assembled and welded onto the plate that serves as the assembly bottom surface to form the U-shaped structure.

[0017] Furthermore, the standard plates in step S3 include standard plates with thicknesses of 1mm, 5mm, 10mm and 20mm respectively. The standard plates are fixed to the flat frame with bolts, and the support elevation of the corresponding position is adjusted by adjusting the combination and quantity of the thickness of the standard plates.

[0018] Furthermore, in step S3, after assembling the upper wall panel, the welds between the inner partition and the upper wall panel, the main welds of the box structure, and the butt welds between the wall panels and the cover plate between the three small sections are completed in sequence.

[0019] Furthermore, the butt welds between the three segments are welded in the following order: first, the welds between the cover plates are welded from bottom to top and symmetrically on both sides; then, the butt welds between the lower wall plates are welded from the middle to both sides; and finally, the butt welds between the upper wall plates are welded.

[0020] Furthermore, the three major sections are simultaneously fabricated as small U-shaped structures on different flat frame work surfaces, and flat frames for overall assembly of the major sections are erected while the U-shaped structures are being fabricated.

[0021] Furthermore, in step S5, the flange assembly is temporarily positioned by spot welding without final connection welding; after the overall spatial dimensions of the three large sections meet the requirements, the connection welding between the flange plate and the corresponding box body is completed.

[0022] Beneficial effects

[0023] 1. The present invention first creates a U-shaped structure with one side open on the flat frame, so that internal components such as longitudinal stiffeners, inner partitions, junction boxes and conduits can be assembled and welded before the box is closed, which is conducive to forming an operable internal construction space.

[0024] 2. By further dividing the major sections into multiple smaller sections, U-shaped structures can be fabricated in parallel on multiple flat frame work surfaces, and the overall assembly frame of the major sections can be erected simultaneously during this period, reducing waiting time and site occupation.

[0025] 3. After the U-shaped structure has the corresponding rigidity, it is flipped to the on-site installation posture with the arched surface facing down. By forming a support surface that matches the various elevation positions of the lower wall panel through standard plates of different thicknesses and quantities, the design arch value can be maintained on the basis of using a flat frame.

[0026] 4. The three large sections are pre-assembled horizontally as a whole by connecting flanges with bolts. The overall space dimensions are checked first, and then the final connection welding between the flange plate and the box body is completed. This helps to ensure the overall connection accuracy of the large-span gantry frame.

[0027] 5. By coordinating the predetermined welding sequence of short butt welds, this invention can balance processing efficiency and overall component size control, enabling efficient, rapid, and precise manufacturing of large box-type gantry frames. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the first-level segmentation of the gantry frame according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram illustrating the second-level segmentation of a large segment according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of a small segment of an embodiment of the present invention;

[0031] Figure 4 This is another schematic diagram of an embodiment of the present invention;

[0032] Figure 5 This is another schematic diagram of a small segment of an embodiment of the present invention;

[0033] Figure 6 for Figure 2 BB section view;

[0034] Figure 7 for Figure 2 Sectional view of AA;

[0035] Figure 8 This is a front view of the gantry frame erection and base plate assembly according to an embodiment of the present invention;

[0036] Figure 9 This is a top view of the gantry frame erection and base plate assembly according to an embodiment of the present invention;

[0037] Figure 10 This is a schematic diagram of a gantry frame U-shaped structure rotating counterclockwise by 90 degrees according to an embodiment of the present invention;

[0038] Figure 11 This is a front view of the assembly of the overall U-shaped structure of the gantry frame according to an embodiment of the present invention;

[0039] Figure 12 for Figure 11 EE section view;

[0040] Figure 13 This is a front view of the assembly of an integral box-type structure of a gantry frame according to an embodiment of the present invention;

[0041] Figure 14 for Figure 13 FF section view;

[0042] Figure 15 This is a schematic diagram of the welding positions of a single-section gantry frame according to an embodiment of the present invention;

[0043] Figure 16 This is a schematic diagram of the segmented interface form of a single-segment gantry frame according to an embodiment of the present invention;

[0044] Figure 17 This is a schematic diagram of a single-section gantry frame connecting flange plate according to an embodiment of the present invention;

[0045] Figure 18 This is a schematic diagram of a horizontal pre-assembly of a three-section gantry frame according to an embodiment of the present invention;

[0046] Figure 19 for Figure 18 Middle GG sectional view;

[0047] Figure 20 This is a schematic diagram of the processing flow according to an embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] As shown in the figure, one embodiment of the present invention provides a welding method for a variable cross-section square tube. This embodiment takes a large-span box-type gantry frame for highways as an example. The gantry frame has multiple junction boxes, conduits, and other accessories arranged inside. Its overall cross-section is approximately 2m × 2m, the wall panel thickness is 30mm, the span is close to 100m, and the overall weight is approximately 200t. Considering the characteristics of the large component cross-section, complex internal piping, large span, and high overall dimensional accuracy requirements, the following process is followed for fabrication.

[0050] (a) Two-level segmentation

[0051] As shown in the figure, the single gantry frame is first segmented into three large sections 1, with adjacent large sections 1 connected by flange plates 2. Each large section 1 is approximately 35m long. Due to limitations in the available steel plate length, each large section 1 is then further segmented into three smaller sections. For example, the first large section 1 is divided along its length into smaller sections 1-1, 1-2, and 1-3. These smaller sections are ultimately welded together in the factory to form a single large section, with the butt welds of adjacent wall panels staggered along the length to avoid concentrating the butt joints of multiple wall panels at the same cross-section.

[0052] (II) Fabrication of short U-shaped structures

[0053] The wall panels with arching requirements are CNC cut to form an arc-shaped panel with the designed arching value. The flat frame 11 is pre-pressed and leveled, and the non-arched surface of each small section is used as the assembly bottom surface. The plate that constitutes the assembly bottom surface is placed on the flat frame 11. The plate here is the cover plate 10.

[0054] For each segment, the longitudinal stiffener 3, inner partition 4, junction box 5, conduit 6, lower wall panel 8, upper wall panel 9, and cover plate 10 are sequentially assembled and welded on the assembly bottom surface. The conduit 6 is installed on the pipe support 7. The wall panels mentioned below refer to the lower wall panel 8 and the upper wall panel 9, forming a U-shaped structure with one side open for each segment. Since the upper wall panel 9 is not yet closed, the stiffening components, partitions, and pipeline accessories inside the box have open assembly space. The segments corresponding to the three large segments can be fabricated simultaneously on different flat jig work surfaces.

[0055] After each segment of the U-shaped structure is completed and has the corresponding stiffness, according to Figure 10 Rotate the U-shaped structure 90° counterclockwise in the direction shown, so that the rotated U-shaped structure is in the same spatial posture as the on-site installation state, and the lower wall panel with arching requirements faces the overall flat frame.

[0056] (III) Overall assembly of large box-type structures

[0057] The three smaller U-shaped structural segments of the same large section were hoisted together onto the overall flat frame and aligned along their length. To prevent the camber of the U-shaped structure from being damaged during support, standard plates with thicknesses of 1mm, 5mm, 10mm, and 20mm were placed between the lower wall panel and the flat frame, and the standard plates were fixed to the flat frame with bolts. According to the design elevation of each position of the lower wall panel, the combination and number of standard plate thicknesses were adjusted so that the flat frame formed a support surface that fits snugly against the lower wall panel at each elevation position.

[0058] After adjusting the relative positions and arching of the three small U-shaped structures, the upper wall panels are assembled to enclose the box. First, the welds between the inner partition and the upper wall panel are completed, then the main welds of the box structure are completed, and the butt welds of the wall panels and cover plates between small sections 1-1, 1-2 and 1-3 are completed, so that the three small sections form a complete large box structure.

[0059] (iv) Welding sequence of small segment interfaces

[0060] When welding the butt joints between the three smaller sections, first weld the joints between the cover plates; the cover plate welds are made from bottom to top and symmetrically welded on both sides of the box body. Next, weld the butt joints between the lower wall panels, starting from the center and working outwards. Finally, weld the butt joints between the upper wall panels. Complete the fabrication of the remaining two large box-shaped sections using the same process. The three large sections can be fabricated simultaneously, and the flat frame required for the overall assembly of the large sections can be erected concurrently with the fabrication of the smaller U-shaped sections.

[0061] (v) Three large horizontal pre-assembly sections

[0062] The flange plates at the ends of adjacent large sections are bolted together to form flange assemblies. Each flange assembly is placed at the installation position at the end of the corresponding large section and temporarily positioned by spot welding. At this time, the final connection welding between the flange plate and the box body is not completed.

[0063] The three large sections are placed horizontally on a flat frame, and the entire gantry is pre-assembled using bolted connections of the flange assemblies. The overall spatial dimensions of the gantry are then measured. Once the overall spatial dimensions meet the requirements, the connecting welds between the flange plates and the corresponding gantry box bodies are welded. After welding, the bolt connections of the flange assemblies are released, and the three large sections are disassembled and individually protected for subsequent transportation and on-site installation.

[0064] Through the above processing and manufacturing process, multiple U-shaped structures are first formed in parallel working surfaces using a flat jig. Then, the rigidity of the U-shaped structure itself is used to complete the flipping and large-section overall sealing. At the same time, the arched state is maintained by combining standard plates. Before the final welding of the flange, the overall spatial dimensions are checked by three large-section horizontal pre-assembly. This achieves efficient, fast and precise manufacturing of large box-type gantry frames.

Claims

1. A method for segmented welding and pre-assembly of a large box-type gantry frame, characterized in that: Includes the following steps: S1. Divide the gantry frame into two levels, dividing a single gantry frame into three large sections. The three large sections are connected by flange plates, and each large section is divided into three small sections, so that the mating positions of adjacent wall panels are staggered. S2. Produce each segment separately, using the non-arched surface of each segment as the assembly bottom surface. Assemble the internal components and box panels on the flat jig and weld them to form a U-shaped structure with one side open, so that multiple segments can be produced simultaneously on multiple flat jig working surfaces. S3. Rotate the three smaller U-shaped sections of the same large section by 90° to the same spatial posture as the on-site installation state. Place the three smaller U-shaped sections together on the overall flat frame. Set standard plates of different thicknesses and quantities between the flat frame and the lower wall panel with arching requirements, so that the support surface of the frame is in contact with the lower wall panel at each elevation position. Then assemble the upper wall panel and complete the butt welding between the three smaller sections to form a large closed box structure. S4. Complete the production of the three main sections simultaneously according to steps S2 and S3; S5. Connect the flange plates at the ends of adjacent large sections with bolts to form a flange group. Temporarily position the flange group at the end of the corresponding large section. Place the three large sections horizontally on the flat jig for overall pre-assembly and spatial dimension measurement. After the measurement results meet the requirements, weld the connection between the flange plate and the corresponding box body, then release the bolt connection of the flange group and disassemble the three large sections.

2. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: Each large section is approximately 35m long, and the three smaller sections are arranged sequentially along the length of the large section.

3. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: In step S1, the butt welds of each wall panel within the same large section are staggered along the length direction.

4. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: Before step S2, the wall panel with arching requirements is cut by CNC, so that the cut wall panel forms an arc-shaped panel with the designed arching value.

5. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: In step S2, longitudinal stiffeners, inner partitions, junction boxes, conduits, lower wall panels, and cover plates are sequentially assembled and welded onto the plate that serves as the assembly bottom surface to form the U-shaped structure.

6. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: The standard plates in step S3 include standard plates with thicknesses of 1mm, 5mm, 10mm and 20mm respectively. The standard plates are fixed to the flat frame with bolts, and the support elevation of the corresponding position is adjusted by adjusting the combination and quantity of the thickness of the standard plates.

7. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: In step S3, after assembling the upper wall panel, the welds between the inner partition and the upper wall panel, the main welds of the box structure, and the butt welds between the wall panels and the cover plate between the three small sections are completed in sequence.

8. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 7, characterized in that: The butt welds between the three sections are welded in the following order: first, the welds between the cover plates are welded from bottom to top and symmetrically on both sides; then, the butt welds between the lower wall plates are welded from the middle to both sides; and finally, the butt welds between the upper wall plates are welded.

9. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: The three main sections are simultaneously fabricated as small U-shaped structures on different flat frame work surfaces, and flat frames for overall assembly of the main sections are erected while the U-shaped structures are being fabricated.

10. The method for segmented welding and pre-assembly of a large box-type gantry frame according to claim 1, characterized in that: In step S5, the flange assembly is temporarily positioned by spot welding without final connection welding; after the overall spatial dimensions of the three large sections meet the requirements, the connection welding between the flange plate and the corresponding box body is completed.

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