Construction method for propeller strut of double-boom derrick crane

Abstract

The invention relates to a construction method of a propeller strut of a double-boom derrick mast crane. The construction method comprises the following steps: S1, in-site subsection manufacturing: dividing the propeller strut into three subsections, namely an upper cross beam, a front leg and a rear leg, and respectively manufacturing the three subsections; s2, outfield splicing and folding: pre-splicing an upper cross beam with a front leg, trimming and cutting the allowance of a folding opening, folding and splicing all components of the front leg to obtain a front leg sheet body, hoisting the front leg sheet body on a ship, fixing the front leg sheet body by utilizing a process support, turning over the upper cross beam, integrally splicing the upper cross beam with a rear leg to obtain a total component, integrally machining hinge point holes of the upper cross beam, installing outfitting pieces, and coating to obtain the front leg. And finally, the coated total assembly is hoisted to a ship to be subjected to final assembly folding with the front leg sheet body. According to the construction method for the propeller strut of the double-boom derrick mast crane, the size of each node of the propeller strut can be accurately controlled, and the uniform transmission performance of variable-amplitude tension of the propeller strut and counter force of a rotary table is ensured.

Description

Technical Field

[0001] This invention relates to the field of A-frame construction technology, and more particularly to a method for constructing an A-frame using a double-arm derrick crane. Background Technology

[0002] A double-boom derrick crane is a special lifting equipment that combines a double-boom structure with derrick technology. Its A-frame includes an upper crossbeam, rear legs, and front legs. The upper crossbeam connects to the top of the rear and front legs, forming an A-shape with them. The rear leg consists of two parallel rear leg main tubes, and the front leg consists of two connected front leg main tubes and a support pipe assembly connecting the two front leg main tubes. The support pipe assembly includes five support pipes, one of which is a middle support pipe, with both ends connected to the two front leg main tubes. The other four support pipes are diagonal support pipes, arranged in pairs on the upper and lower sides of the middle support pipe. The two diagonal support pipes in the same pair are arranged in a V-shape. The top ends of the two diagonal support pipes on the upper side of the middle support pipe are connected to the upper crossbeam, and the bottom ends are connected to the two front leg main tubes. The top ends of the two diagonal support pipes on the lower side of the middle support pipe are connected to the middle support pipe, and the bottom ends are connected to the two front leg main tubes.

[0003] As the main load-bearing structure of a double-boom derrick crane, the A-frame requires precise control of the dimensions of each node to ensure the uniform transmission of luffing force and turntable reaction force, avoiding localized stress concentration that could lead to failure. Therefore, higher requirements are placed on the manufacturing and assembly precision of each A-frame segment. Furthermore, the construction platform at the A-frame closure joint is typically erected during closure, requiring prolonged crane suspension and installation, and resulting in high construction costs.

[0004] Therefore, this invention proposes a method for constructing the A-frame of a double-arm derrick crane to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for constructing an A-frame of a double-arm derrick crane, which can accurately control the dimensions of each node of the A-frame, ensure the uniform transmission performance of the A-frame luffing tension and turntable reaction force, improve the smoothness of construction, ensure the closing accuracy, and reduce construction costs.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for constructing an A-frame of a double-boom derrick crane, the innovation of which lies in the following steps: S1. In-situ segmented construction: The A-frame is divided into three segments: upper crossbeam, front leg and rear leg, and constructed separately. The construction of the front leg includes three components: front leg main tube, middle support tube and diagonal support tube. After the construction of each component of the front leg is completed, it is painted. The construction of the rear leg includes the construction of the rear leg main tube component. S2. Outdoor Assembly and Joining: Pre-assemble the upper crossbeam with the front legs, trimming the allowance at the joining joint. Assemble all components of the front legs to obtain the front leg body. Pre-install process supports on the front leg body. Then, install scaffolding platforms at the joining joints of the front leg main pipe and the inclined support pipe of the front leg body. Erect a scaffolding ladder and railings between the scaffolding platforms at the joining joints of the upper crossbeam and the inclined support pipe. Divide the product's scaffolding ladder into two sections and erect them on the upper crossbeam and the front leg main pipe respectively. The inclined ladders of each product section are raised to be parallel to the main front leg using channel steel. Then, the front leg panels are hoisted onto the ship and fixed with process bracing. After the upper crossbeam is flipped over, it is assembled with the rear leg to obtain the final assembly. The hinge point holes of the upper crossbeam are machined as a whole, outfitting parts are installed, and painting is performed. Finally, the painted final assembly is hoisted onto the ship and assembled with the front leg panels. The two inclined ladders of the product are connected. After the connection is made, the channel steel is cut off and the paint is repaired. After the final assembly is completed, all scaffolding platforms are dismantled.

[0007] Furthermore, the scaffolding platform includes several platform components, which surround the front leg main tube or inclined support tube and cooperate to form a stepped construction channel; Each platform component includes two supports and a platform plate. Each support includes an I-beam, a connecting plate, a bottom support plate, and a pressure plate. The connecting plate of each support is located in the radial direction of the front leg main tube or inclined support tube. The connecting plate is welded to the side wall of the front leg piece. The upper and lower flange plates of the I-beam are respectively located on the upper and lower sides of the connecting plate. The web of the I-beam is attached to the connecting plate and fixed by bolts. The bottom support plate is located below the I-beam and is welded to the lower flange plate of the I-beam. The bottom support plate and the web of the I-beam are on the same plane. The pressure plate is located between the bottom support plate and the front leg piece. One side of the pressure plate is welded perpendicularly to the bottom support plate, and the other side contacts and abuts against the side wall of the front leg piece. The platform plate is located above the two supports, and the two sides of the platform plate are fixedly connected to the I-beams of the two supports respectively.

[0008] Furthermore, the manufacturing process of the front leg main tube, the intermediate support tube, the diagonal support tube, and the rear leg main tube includes: S1.1, Panel Assembly: After the steel plates are cut and shaped, they are welded and assembled to obtain panel assembly. The dimensions of the panel assembly are inspected before and after welding. The weld seams of the panel assembly are inspected for flaws. After the panel assembly passes the inspection, it is sent to the plate rolling workshop for rolling. S1.2 Rolling: Place the spliced ​​panels on the rolling machine, adjust the perpendicularity of the spliced ​​panels to the rollers of the rolling machine according to the center line and inspection line of the spliced ​​panels, and start rolling. Use a template to check whether the roundness meets the requirements. Stop rolling after it is qualified. After the whole circle is rolled, the cylinder is obtained. Use a clamp to fix the longitudinal seam of the cylinder firmly. S1.3, Longitudinal seam welding: Arrange the roller frame and level it. Hoist the rolled cylinder onto the roller frame, remove the jammer, build a longitudinal seam welding platform using scaffolding, install the arc extinguishing plate and weld the longitudinal seam. When cutting off the arc extinguishing plate after welding, leave 3~5mm for grinding. After the weld is inspected and qualified, restore it to round shape. After restoration to round shape, perform accuracy measurement. S1.4 Cylinder Assembly: After each cylinder is assembled using an assembly machine or roller frame, it is fixed by positioning welding, followed by continuous root welding. The longitudinal seams of adjacent cylinders need to be staggered by 180°. After the circumferential seam assembly and welding, the accuracy measurement is carried out to adjust the misalignment and straightness of the cylinders.

[0009] Furthermore, in step S1.1, when inspecting the dimensions of the panels, the flatness error of the panels is required to be no more than 1mm / m, and the overall error is ≤3mm. The length and width deviations are ±2mm, the diagonal deviations are ±3mm, and the structural misalignment deviations are required to be ≤3mm.

[0010] Furthermore, in step S1.2, after obtaining the cylinder after rolling and shaping, 0°, 90°, 180°, and 270° are marked on-site. In steps S1.3 and S1.4, the accuracy measurement is performed according to the four-part division line from 0° to 270°.

[0011] Furthermore, in step S1.2, when the longitudinal seam of the cylinder is securely fixed with clamps, the clamp spacing is required to be ≤400mm, and the bottom weld is fixed by intermittent welding at 100~150mm intervals, with a bottom weld depth ≥6mm.

[0012] Furthermore, in step S1.3, after the longitudinal seam of the cylinder is welded, the cylinder roundness deviation is required to be ±3mm, the outer circumference deviation is <10mm, the misalignment at the butt joint is <3mm, and the flatness of the end face is ≤2mm.

[0013] Furthermore, in step S1.4, the circumferential seam of the cylinder is required to be ≤3mm after assembly, the straightness deviation is required to be 1mm / m, and it shall not exceed 3mm within a 3m range, 5mm within any 10m range, 10mm within any 20m range, and the overall deviation shall not exceed 15mm. The overall length deviation is required to be ±10mm, the allowable deviation of the outer circumference of the cylinder is ≤10mm, the allowable deviation of the ellipticity of the cylinder is ≤6nn, and the allowable deviation of the flatness of the cylinder end is 4mm.

[0014] Furthermore, the pre-assembly process of the upper crossbeam and the front leg piece includes: S2.1.1 Marking and Frame Layout: First, mark the center line of the front leg cross on the ground. Then, using the center line of the front leg cross as a reference, mark the center line of the upper crossbeam, the main front leg pipe, the middle support pipe, and the diagonal support pipe. The marking deviation should be ±1mm. Arrange the pre-assembled frame according to the frame layout. The overall levelness deviation of the pre-assembled frame should be ±3mm. Use shims to level uneven areas on the ground. S2.1.2 Upper crossbeam flipping and positioning on the pre-assembled assembly frame: The upper crossbeam is flipped over using a gantry and hoisted onto the pre-assembled assembly frame. The horizontal level of the upper crossbeam is corrected by laser to align the horizontal center line of the upper crossbeam with the horizontal center line of the front leg main pipe. The verticality of the upper crossbeam in this state is checked with a plumb bob to ensure that the angle between the center lines of the rear legs on both sides of the upper crossbeam and the horizontal center line of the front leg main pipe meets the design requirements. S2.1.3 Front Leg Main Tube Positioning: Hoist the front leg main tube onto the pre-assembled assembly frame, use laser to correct the level of the front leg main tube, and use a plumb bob to align the center line of the front leg main tube's cylinder with the center line on the ground and the center line of the intermediate support tube. Correct the slope of the front leg main tube, cut off the excess material of the closure joint, and open the welding bevel. Fix the pre-assembled closure joint with a clamp, fix the front leg main tube on both sides of the frame with baffles, and install the insert plates of each support tube. S2.1.4, Positioning of the support pipe: Hoist the middle support pipe and each inclined support pipe into place, and fix the pre-assembled joint with clamps; S2.1.5 Welding after pre-welding inspection: After the pre-welding dimensions are inspected and approved, the whole welding is carried out. First, weld the joint between the front leg main pipe and the upper crossbeam, then weld the joint between the front leg main pipe and the middle support pipe, and finally weld the weld between the inclined support pipe and the insert plate. It is required to weld symmetrically on both sides, observe the welding deformation in time, and re-measure the opening size of the lower end of the front leg and the overall length size after welding. After the structure is inspected and approved, the front leg piece is obtained. S2.1.6, Installation of outfitting platform integrity: Remove the pre-assembled clamps of the front legs, use a flatbed truck to turn the front leg body 90°, then flip the front leg body over and place it on the jig frame. After flipping it over, install the front leg outfitting platform integrity and touch up any damaged areas with paint.

[0015] Furthermore, the process of assembling the upper crossbeam with the rear leg includes: S2.2.1 Marking and Frame Arrangement: First, mark the ground layout lines on the ground for the center lines of the rear leg center line, the center line of the upper crossbeam luffing pulley hole, and the center line of the rear leg main pipe. The marking deviation should be ±1mm. Arrange the assembly frame according to the ground layout lines. The overall levelness deviation of the assembly frame should be ±3mm. Use shims to level uneven areas of the ground. S2.2.2, Upper crossbeam flipping onto the jig: After flipping the upper crossbeam using a gantry crane, lift it onto the assembled jig. Use laser to correct the level of the upper crossbeam so that the horizontal center line of the upper crossbeam is aligned with the horizontal center line of the rear leg main pipe. Use a plumb bob to check the verticality of the upper crossbeam in this state to ensure that the angle between the center lines of the front legs on both sides of the upper crossbeam and the horizontal center line of the rear leg main pipe meets the design requirements. S2.2.3, Rear Leg Main Tube Positioning: Hoist the rear leg main tube onto the assembly jig, use laser to correct the level of the rear leg main tube, and use a plumb bob to align the center line of the rear leg main tube's cylinder with the center line on the ground. Correct the slope of the rear leg main tube, cut off the excess material of the joining joint, and open the welding bevel. Use a clamp to fix the pre-assembled joining joint, and use baffles to fix the two sides of the rear leg main tube on the jig. S2.2.4 Welding and Machining: After pre-welding inspection, weld the closure of the rear leg main pipe. Welding should be carried out symmetrically on both sides simultaneously. After welding, re-measure the opening size of the lower end of the rear leg and the overall length size. The lower end opening deviation should be ±5mm, the overall length deviation should be ±5mm, and the levelness should be ±5mm. After overall leveling, machine and scribing should be carried out, and shaft holes should be machined. The rear leg outfitting platform should be installed intact, and any local damage should be repaired.

[0016] The advantages of this invention are: (1) The construction method of the A-frame of the double-arm derrick crane of the present invention divides the A-frame into three sections: the upper crossbeam, the front leg and the rear leg, which are manufactured on site respectively. The front leg and the rear leg are manufactured as components. This not only allows for targeted use of CNC cutting and welding processes to ensure the dimensional accuracy of individual parts, but also allows for the simultaneous manufacture of multiple components, effectively shortening the manufacturing period. When assembling each section, in order to ensure the final assembly size of the A-frame on the ship, the upper crossbeam and the front leg are pre-assembled, and the allowance at the joint is trimmed to ensure the docking accuracy of the front leg pieces and the upper crossbeam. Then the upper crossbeam is assembled. After being flipped over, the upper beam and rear leg are assembled together. Then, the hinge point holes are machined as a whole to form the assembly of the upper beam and rear leg, effectively eliminating the cumulative error of segmented manufacturing and controlling the accuracy of the hinge point holes. Before the final assembly, a scaffolding platform for the closure joint construction and an inclined ladder for climbing the scaffolding platform are installed. This not only provides workers with a stable and safe working surface, but also effectively reduces the preparation time for the closure segment. During the closure, personnel and equipment can directly engage in the core work, avoiding interference from poor conditions, greatly improving the smoothness of construction, ensuring closure accuracy, and reducing construction costs.

[0017] (2) The A-frame of the present invention decomposes each component of the front leg and the rear leg into standardized cylindrical units, and through standardized processes of splicing, rolling, longitudinal seam welding, and circumferential seam welding after assembly, and strictly controls the dimensional accuracy of each process, ensures the overall size of the front leg and the rear leg as well as the subsequent assembly accuracy, thereby achieving synergistic optimization of quality and efficiency. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 This is a schematic flowchart illustrating the construction method of the A-frame of the double-arm derrick crane according to the present invention.

[0020] Figure 2 This is a front view of the structural segments of the A-frame of the double-arm boom crane of the present invention.

[0021] Figure 3 This is an M-direction view of the structural segments of the A-frame of the double-arm boom crane of the present invention. Figure 4 This is an N-direction view of the structural segments of the A-frame of the double-arm boom crane of the present invention.

[0022] Figure 5 This is a schematic diagram of the structure of the cylinder assembly of the present invention.

[0023] Figure 6 This is a cross-sectional view of section AA of the cylinder assembly of the present invention.

[0024] Figure 7 This is a cross-sectional view of the BB section of the cylinder assembly of the present invention.

[0025] Figure 8 This is a flowchart of the field assembly and joining process of the present invention.

[0026] Figure 9 This is a schematic diagram showing the distribution of the inclined ladder, scaffolding ladder, and construction platform of the present invention on the A-frame.

[0027] Figure 10 This is a schematic diagram showing the installation of a scaffolding platform and a product inclined ladder at the closing opening of the front leg main tube of the present invention.

[0028] Figure 11 This is a schematic diagram showing the installation of a scaffolding platform and a scaffolding ladder at the junction of the inclined support tubes of the present invention.

[0029] Figure 12 This is a top view of the scaffolding platform of the present invention.

[0030] Figure 13 This is a cross-sectional view of the EE section of the scaffolding platform of the present invention.

[0031] Figure 14 This is a schematic diagram of the structure of the bracket of the present invention. Detailed Implementation

[0032] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0033] This embodiment provides a method for constructing an A-frame for a double-boom derrick crane, such as... Figure 1 As shown, it includes the following steps: S1. Segmented production within the venue; like Figures 2-4As shown, the A-frame includes an upper crossbeam 1, rear legs 2, and front legs 3. The upper crossbeam 1 is connected to the top of the rear legs 2 and the front legs 3, and together with the rear legs 2 and the front legs 3, they form an A-shaped structure. The rear legs 2 consist of two parallel rear leg main tubes 2-1. The front legs 3 consist of two connected front leg main tubes 3-1 and a support tube assembly connecting the two front leg main tubes 3-1. The support tube assembly includes five support tubes, one of which is a middle support tube 3-2, with both ends of the middle support tube 3-2 connected to the two front leg main tubes 3-1 respectively. The other four support tubes are diagonal support tubes 3-3, which are arranged in pairs on the upper and lower sides of the middle support tube 3-2. The two diagonal support tubes 3-3 in the same group are arranged in a V-shape. The top ends of the two diagonal support tubes located on the upper side of the middle support tube 3-2 are connected to the upper crossbeam, and the bottom ends are connected to the two front leg main tubes respectively. The top ends of the two diagonal support tubes located on the lower side of the middle support tube are connected to the middle support tube, and the bottom ends are connected to the two front leg main tubes respectively.

[0034] Based on the characteristics of the A-frame structure, the A-frame is divided into three sections: upper crossbeam 1, front leg 3, and rear leg 2, which are manufactured separately. The manufacturing of front leg 3 includes the manufacturing of front leg main tube 3-1 component, middle support tube 3-2 component, and diagonal support tube 3-3 component. After the components of front leg 3 are manufactured, they are painted. The manufacturing of rear leg 2 includes the manufacturing of rear leg main tube 2-1 component.

[0035] The manufacturing process of the front leg main tube 3-1, the middle support tube 3-2, the diagonal support tube 3-3, and the rear leg main tube 2-1 includes: S1.1, Panel Assembly: After the steel plates are cut and shaped, they are welded and assembled to obtain panels. The panels are inspected for dimensions before and after welding. The flatness error of the panels is required to be no more than 1mm / m, and the overall error is ≤3mm. The length and width deviation is ±2mm, the diagonal deviation is ±3mm, and the structural misalignment deviation is ≤3mm. The weld seams of the panels are inspected for flaws. After the panels pass the inspection, they are sent to the rolling workshop for rolling. S1.2 Rolling: Place the spliced ​​panels on the rolling machine. Adjust the perpendicularity of the spliced ​​panels to the rollers of the rolling machine according to the center line and inspection line of the spliced ​​panels, and start rolling. Use a template to check whether the roundness meets the requirements. Stop rolling after passing the test. After the whole circle is rolled, the cylinder is obtained. Mark 0°, 90°, 180° and 270° on site for subsequent installation and precision control. Use clamps to fix the longitudinal seam of the cylinder firmly. The clamp spacing should be ≤400mm. Weld the bottom layer at 100~150mm intervals and fix it with a bottom weld depth ≥6mm. S1.3, Longitudinal seam welding: Set up the roller frame and level it. Hoist the rolled cylinder onto the roller frame, remove the jammer, and use scaffolding to build a longitudinal seam welding platform. Install the arc-extinguishing plate to weld the longitudinal seam. When cutting off the arc-extinguishing plate after welding, leave 3-5mm for grinding. After the weld is inspected and qualified, it is rounded back. After rounding, the accuracy measurement is carried out. The accuracy measurement is carried out according to the four equal division lines of 0°~270°. The cylinder roundness deviation is required to be ±3mm, the outer circle circumference deviation is <10mm, the misalignment at the butt joint is <3mm, and the end face flatness is ≤2mm.

[0036] S1.4, Cylinder Assembly: After each cylinder is assembled using an assembly machine or roller frame, it is fixed by tack welding, followed by continuous root pass welding, such as... Figures 5-7 As shown, the longitudinal seams of adjacent cylinders must be staggered by 180°. After the circumferential seam assembly and welding, precision measurement is performed to adjust the misalignment and straightness of the cylinders. During precision measurement, measurements are taken along the four equal division lines from 0° to 270°. The circumferential seam of the cylinders after assembly must be ≤3mm, the straightness deviation must be 1mm / m, and it must not exceed 3mm within a 3m range, 5mm within any 10m range, 10mm within any 20m range, and the overall deviation must not exceed 15mm. The overall length deviation must be ±10mm, the allowable deviation of the outer circumference of the cylinder must be ≤10mm, the allowable deviation of the ellipticity of the cylinder must be ≤6mm, and the allowable deviation of the flatness of the cylinder ends must be 4mm.

[0037] During the on-site segmented manufacturing process, the components of the front and rear legs are decomposed into standardized cylindrical units. Through standardized processes such as panel splicing, rolling, longitudinal seam welding, and circumferential seam welding after assembly, as well as strict control over the dimensional accuracy of each process, the overall dimensions of the front and rear legs and the subsequent assembly accuracy are ensured, achieving synergistic optimization of quality and efficiency.

[0038] In this embodiment, the process of manufacturing the upper crossbeam includes panel assembly and box assembly. The panel assembly process and precision control are the same as in step S1.1. When assembling the box, a jig is arranged in advance, and the box is assembled from the middle to both sides on the jig and then welded symmetrically.

[0039] The construction method of the A-frame of the double-arm derrick crane divides the A-frame into three sections: the upper crossbeam, the front leg, and the rear leg, which are fabricated on site. The front leg and rear leg, which are large in size, are fabricated as components. This not only allows for targeted use of CNC cutting and welding processes to ensure the dimensional accuracy of individual parts, but also enables the simultaneous fabrication of multiple components, effectively shortening the production period.

[0040] S2. Outdoor assembly and assembly: such as Figure 8 As shown, the upper crossbeam is pre-assembled with the front leg, the allowance at the joining joint is trimmed, and the various components of the front leg are assembled to obtain the front leg body. The process bracing is then pre-installed on the front leg body. Then, scaffolding platforms 4 are installed at the joining joints of the front leg main pipe and the inclined support pipe of the front leg body, respectively. Figure 9-11As shown, a scaffolding ladder 5 and railings are erected between the scaffolding platform at the junction of the upper crossbeam and the inclined support pipe. The product ladder 6 is divided into two sections and erected on the upper crossbeam and the front leg main pipe respectively. Channel steel 7 is used to raise each section of the product ladder parallel to the front leg main pipe. After the front leg piece is hoisted onto the ship, it is fixed with process bracing. After the upper crossbeam is flipped over, it is assembled with the rear leg to obtain the whole component. The hinge point holes of the upper crossbeam are machined as a whole, outfitting parts are installed, and painting is performed. Finally, the painted whole component is hoisted onto the ship and assembled with the front leg piece. The two sections of the product ladder are connected. After the connection is made, the channel steel is cut off and the paint is repaired. After the whole assembly is completed, each scaffolding platform is dismantled.

[0041] like Figure 12-14 As shown, the scaffolding platform 4 includes eight platform components. These eight components surround the front leg main pipe or inclined support pipe and cooperate to form a stepped construction channel. Each platform component includes two supports and a platform plate 4-5. Each support includes an I-beam 4-1, a connecting plate 4-2, a bottom support plate 4-3, and a pressure plate 4-4. The connecting plate 4-2 of each support is located in the radial direction of the front leg main pipe or inclined support pipe and is welded to the side wall of the front leg plate. The upper and lower flange plates of the I-beam 4-1 are respectively located on the upper and lower sides of the connecting plate 4-2. The web of the I-beam 4-1 is attached to the connecting plate 4-2 and fixed by bolts. Support plate 4-3 is located below I-beam 4-1 and is welded to the lower flange of I-beam 4-1. Bottom support plate 4-3 and web of I-beam 4-1 are on the same plane. Pressure plate 4-4 is located between bottom support plate 4-3 and front leg body. One side of pressure plate 4-4 is welded perpendicularly to bottom support plate 4-3, and the other side contacts and abuts against the side wall of front leg body. Platform plate 4-5 is located above two supports. Both sides of platform plate 4-5 are fixedly connected to I-beam 4-1 of the two supports respectively.

[0042] During the installation of scaffolding platform 4, minor trimming of the I-beams and bottom support plates is required to ensure that the platform plate of the platform assembly is level after the front leg body is hoisted onto the ship and fixed by the process bracing. When the scaffolding platform is dismantled after the final assembly is completed, the connecting plate is left on the front leg body and painted as required.

[0043] The pre-assembly process of the upper crossbeam and the front leg pieces includes: S2.1.1 Marking and Frame Layout: First, mark the center line of the front leg cross on the ground. Then, using the center line of the front leg cross as a reference, mark the center lines of the upper crossbeam, front leg main pipe, intermediate support pipe, and diagonal support pipe. The marking deviation should be ±1mm. Arrange the pre-assembled frame according to the ground layout lines, such as... Figure 8 As shown, the overall levelness deviation of the pre-assembled jig is ±3mm. Use shims to level uneven areas of the ground. S2.1.2 Upper crossbeam flipping and positioning on the pre-assembled assembly frame: The upper crossbeam is flipped over using a gantry and hoisted onto the pre-assembled assembly frame. The horizontal level of the upper crossbeam is corrected by laser to align the horizontal center line of the upper crossbeam with the horizontal center line of the front leg main pipe. The verticality of the upper crossbeam in this state is checked with a plumb bob to ensure that the angle between the center lines of the rear legs on both sides of the upper crossbeam and the horizontal center line of the front leg main pipe meets the design requirements. S2.1.3 Front Leg Main Tube Positioning: Hoist the front leg main tube onto the pre-assembled assembly frame, use laser to correct the level of the front leg main tube, and use a plumb bob to align the center line of the front leg main tube's cylinder with the center line on the ground and the center line of the intermediate support tube. Correct the slope of the front leg main tube, cut off the excess material of the closure joint, and open the welding bevel. Fix the pre-assembled closure joint with a clamp, fix the front leg main tube on both sides of the frame with baffles, and install the insert plates of each support tube. S2.1.4, Positioning of the support pipe: Hoist the middle support pipe and each inclined support pipe into place, and fix the pre-assembled joint with clamps; S2.1.5 Welding after pre-welding inspection: After the pre-welding dimensions are inspected and approved, the whole welding is carried out. First, weld the joint between the front leg main pipe and the upper crossbeam, then weld the joint between the front leg main pipe and the middle support pipe, and finally weld the weld between the diagonal support pipe and the insert plate. It is required to weld symmetrically on both sides and observe the welding deformation in time. After welding, re-measure the opening size of the lower end of the front leg and the overall length size. The opening deviation of the lower end of the front leg is required to be ±5mm, the overall length deviation is required to be ±5mm, and the levelness requirement is ±5mm. After the structure is inspected and approved, the front leg piece is obtained. S2.1.6, Installation of outfitting platform integrity: Remove the pre-assembled clamps of the front legs, use a flatbed truck to turn the front leg body 90°, then flip the front leg body over and place it on the jig frame. After flipping it over, install the front leg outfitting platform integrity and touch up any damaged areas with paint.

[0044] The assembly process of the upper crossbeam and the rear legs includes: S2.2.1 Marking and Frame Arrangement: First, mark the ground layout lines on the ground for the center lines of the rear leg center line, the center line of the upper crossbeam luffing pulley hole, and the center line of the rear leg main pipe. The marking deviation should be ±1mm. Arrange the assembly frame according to the ground layout lines. The overall levelness deviation of the assembly frame should be ±3mm. Use shims to level uneven areas of the ground. S2.2.2, Upper crossbeam flipping onto the jig: After flipping the upper crossbeam using a gantry crane, lift it onto the assembled jig. Use laser to correct the level of the upper crossbeam so that the horizontal center line of the upper crossbeam is aligned with the horizontal center line of the rear leg main pipe. Use a plumb bob to check the verticality of the upper crossbeam in this state to ensure that the angle between the center lines of the front legs on both sides of the upper crossbeam and the horizontal center line of the rear leg main pipe meets the design requirements. S2.2.3, Rear Leg Main Tube Positioning: Hoist the rear leg main tube onto the assembly jig, use laser to correct the level of the rear leg main tube, and use a plumb bob to align the center line of the rear leg main tube's cylinder with the center line on the ground. Correct the slope of the rear leg main tube, cut off the excess material of the joining joint, and open the welding bevel. Use a clamp to fix the pre-assembled joining joint, and use baffles to fix the two sides of the rear leg main tube on the jig. S2.2.4 Welding and Machining: After pre-welding inspection, weld the closure of the rear leg main pipe. Welding should be carried out symmetrically on both sides simultaneously. After welding, re-measure the opening size of the lower end of the rear leg and the overall length size. The opening deviation of the lower end of the rear leg should be ±5mm, the overall length deviation should be ±5mm, and the levelness should be ±5mm. After overall leveling, machine and scribing should be carried out, and shaft holes should be machined. The rear leg outfitting platform should be installed intact, and any local damage should be repaired.

[0045] The A-frame construction method for double-arm derrick cranes involves installing a scaffolding platform and inclined ladders for accessing the scaffolding joint before final assembly. This not only provides workers with a stable and safe working surface but also effectively reduces the preparation time for the closure segment. During closure, personnel and equipment can directly engage in core operations, avoiding interference from poor conditions, significantly improving the smoothness of construction, ensuring closure accuracy, and reducing construction costs.

[0046] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for constructing an A-frame for a double-arm boom crane, characterized in that: Includes the following steps: S1. In-situ segmented construction: The A-frame is divided into three segments: upper crossbeam, front leg and rear leg, and constructed separately. The construction of the front leg includes three components: front leg main tube, middle support tube and diagonal support tube. After the construction of each component of the front leg is completed, it is painted. The construction of the rear leg includes the construction of the rear leg main tube component. S2. Outdoor Assembly and Joining: Pre-assemble the upper crossbeam with the front legs, trimming the allowance at the joining joint. Assemble all components of the front legs to obtain the front leg body. Pre-install process supports on the front leg body. Then, install scaffolding platforms at the joining joints of the front leg main pipe and the inclined support pipe of the front leg body. Erect a scaffolding ladder and railings between the scaffolding platforms at the joining joints of the upper crossbeam and the inclined support pipe. Divide the product's scaffolding ladder into two sections and erect them on the upper crossbeam and the front leg main pipe respectively. The inclined ladders of each product section are raised to be parallel to the main front leg using channel steel. Then, the front leg panels are hoisted onto the ship and fixed with process bracing. After the upper crossbeam is flipped over, it is assembled with the rear leg to obtain the final assembly. The hinge point holes of the upper crossbeam are machined as a whole, outfitting parts are installed, and painting is performed. Finally, the painted final assembly is hoisted onto the ship and assembled with the front leg panels. The two inclined ladders of the product are connected. After the connection is made, the channel steel is cut off and the paint is repaired. After the final assembly is completed, all scaffolding platforms are dismantled.

2. The method for constructing the A-frame of a double-boom derrick crane according to claim 1, characterized in that: The scaffolding platform includes several platform components, which surround the front leg main tube or inclined support tube and cooperate to form a stepped construction channel. Each platform component includes two supports and a platform plate. Each support includes an I-beam, a connecting plate, a bottom support plate, and a pressure plate. The connecting plate of each support is located in the radial direction of the front leg main tube or inclined support tube. The connecting plate is welded to the side wall of the front leg piece. The upper and lower flange plates of the I-beam are respectively located on the upper and lower sides of the connecting plate. The web of the I-beam is attached to the connecting plate and fixed by bolts. The bottom support plate is located below the I-beam and is welded to the lower flange plate of the I-beam. The bottom support plate and the web of the I-beam are on the same plane. The pressure plate is located between the bottom support plate and the front leg piece. One side of the pressure plate is welded perpendicularly to the bottom support plate, and the other side contacts and abuts against the side wall of the front leg piece. The platform plate is located above the two supports, and the two sides of the platform plate are fixedly connected to the I-beams of the two supports respectively.

3. The method for constructing the A-frame of a double-boom derrick crane according to claim 1, characterized in that: The manufacturing process of the front leg main tube, the middle support tube, the diagonal support tube, and the rear leg main tube includes: S1.1, Panel Assembly: After the steel plates are cut and shaped, they are welded and assembled to obtain panel assembly. The dimensions of the panel assembly are inspected before and after welding. The weld seams of the panel assembly are inspected for flaws. After the panel assembly passes the inspection, it is sent to the plate rolling workshop for rolling. S1.2 Rolling: Place the spliced ​​panels on the rolling machine, adjust the perpendicularity of the spliced ​​panels to the rollers of the rolling machine according to the center line and inspection line of the spliced ​​panels, and start rolling. Use a template to check whether the roundness meets the requirements. Stop rolling after it is qualified. After the whole circle is rolled, the cylinder is obtained. Use a clamp to fix the longitudinal seam of the cylinder firmly. S1.3, Longitudinal seam welding: Arrange the roller frame and level it. Hoist the rolled cylinder onto the roller frame, remove the jammer, build a longitudinal seam welding platform using scaffolding, install the arc extinguishing plate and weld the longitudinal seam. When cutting off the arc extinguishing plate after welding, leave 3~5mm for grinding. After the weld is inspected and qualified, restore it to round shape. After restoration to round shape, perform accuracy measurement. S1.4 Cylinder Assembly: After each cylinder is assembled using an assembly machine or roller frame, it is fixed by positioning welding, followed by continuous root welding. The longitudinal seams of adjacent cylinders need to be staggered by 180°. After the circumferential seam assembly and welding, the accuracy measurement is carried out to adjust the misalignment and straightness of the cylinders.

4. The method for constructing the A-frame of a double-boom derrick crane according to claim 3, characterized in that: In step S1.1, when inspecting the dimensions of the panels, the flatness error of the panels is required to be no more than 1mm / m, and the overall error is ≤3mm. The length and width deviations are ±2mm, the diagonal deviations are ±3mm, and the structural misalignment deviations are required to be ≤3mm.

5. The method for constructing the A-frame of a double-boom derrick crane according to claim 3, characterized in that: In step S1.2, after the cylinder is obtained after rolling and forming, 0°, 90°, 180° and 270° are marked on site. When measuring the accuracy in steps S1.3 and S1.4, the measurement is carried out according to the four-part division line from 0° to 270°.

6. The method for constructing the A-frame of a double-boom derrick crane according to claim 3, characterized in that: In step S1.2, when the longitudinal seam of the cylinder is securely fixed with clamps, the clamp spacing should be ≤400mm, and the base weld should be fixed with intermittent welding at 100~150mm intervals, with a base weld depth ≥6mm.

7. The method for constructing the A-frame of a double-boom derrick crane according to claim 3, characterized in that: In step S1.3, after the longitudinal seam of the cylinder is welded, the cylinder roundness deviation is required to be ±3mm, the outer circumference deviation is <10mm, the misalignment at the butt joint is <3mm, and the flatness of the end face is ≤2mm.

8. The method for constructing the A-frame of a double-boom derrick crane according to claim 3, characterized in that: In step S1.4, the circumferential seam of the cylinder should be ≤3mm after assembly, the straightness deviation should be 1mm / m, and should not exceed 3mm within 3m, 5mm within any 10m range, 10mm within any 20m range, and the overall deviation should not exceed 15mm. The overall length deviation should be ±10mm, the allowable deviation of the outer circumference of the cylinder should be ≤10mm, the allowable deviation of the ellipticity of the cylinder should be ≤6mm, and the allowable deviation of the flatness of the cylinder end should be 4mm.

9. The method for constructing the A-frame of a double-boom derrick crane according to claim 1, characterized in that: The pre-assembly process of the upper crossbeam and the front leg piece includes: S2.1.1 Marking and Frame Layout: First, mark the center line of the front leg cross on the ground. Then, using the center line of the front leg cross as a reference, mark the center line of the upper crossbeam, the main front leg pipe, the middle support pipe, and the diagonal support pipe. The marking deviation should be ±1mm. Arrange the pre-assembled frame according to the frame layout. The overall levelness deviation of the pre-assembled frame should be ±3mm. Use shims to level uneven areas on the ground. S2.1.2 Upper crossbeam flipping and positioning on the pre-assembled assembly frame: The upper crossbeam is flipped over using a gantry and hoisted onto the pre-assembled assembly frame. The horizontal level of the upper crossbeam is corrected by laser to align the horizontal center line of the upper crossbeam with the horizontal center line of the front leg main pipe. The verticality of the upper crossbeam in this state is checked with a plumb bob to ensure that the angle between the center lines of the rear legs on both sides of the upper crossbeam and the horizontal center line of the front leg main pipe meets the design requirements. S2.1.3 Front Leg Main Tube Positioning: Hoist the front leg main tube onto the pre-assembled assembly frame, use laser to correct the level of the front leg main tube, and use a plumb bob to align the center line of the front leg main tube's cylinder with the center line on the ground and the center line of the intermediate support tube. Correct the slope of the front leg main tube, cut off the excess material of the closure joint, and open the welding bevel. Fix the pre-assembled closure joint with a clamp, fix the front leg main tube on both sides of the frame with baffles, and install the insert plates of each support tube. S2.1.4, Positioning of the support pipe: Hoist the middle support pipe and each inclined support pipe into place, and fix the pre-assembled joint with clamps; S2.1.5 Welding after pre-welding inspection: After the pre-welding dimensions are inspected and approved, the whole welding is carried out. First, weld the joint between the front leg main pipe and the upper crossbeam, then weld the joint between the front leg main pipe and the middle support pipe, and finally weld the weld between the inclined support pipe and the insert plate. It is required to weld symmetrically on both sides, observe the welding deformation in time, and re-measure the opening size of the lower end of the front leg and the overall length size after welding. After the structure is inspected and approved, the front leg piece is obtained. S2.1.6, Installation of outfitting platform integrity: Remove the pre-assembled clamps of the front legs, use a flatbed truck to turn the front leg body 90°, then flip the front leg body over and place it on the jig frame. After flipping it over, install the front leg outfitting platform integrity and touch up any damaged areas with paint.

10. The method for constructing the A-frame of a double-boom derrick crane according to claim 9, characterized in that: The process of assembling the upper crossbeam with the rear leg includes: S2.2.1 Marking and Frame Arrangement: First, mark the ground layout lines on the ground for the center lines of the rear leg center line, the center line of the upper crossbeam luffing pulley hole, and the center line of the rear leg main pipe. The marking deviation should be ±1mm. Arrange the assembly frame according to the ground layout lines. The overall levelness deviation of the assembly frame should be ±3mm. Use shims to level uneven areas of the ground. S2.2.2, Upper crossbeam flipping onto the jig: After flipping the upper crossbeam using a gantry crane, lift it onto the assembled jig. Use laser to correct the level of the upper crossbeam so that the horizontal center line of the upper crossbeam is aligned with the horizontal center line of the rear leg main pipe. Use a plumb bob to check the verticality of the upper crossbeam in this state to ensure that the angle between the center lines of the front legs on both sides of the upper crossbeam and the horizontal center line of the rear leg main pipe meets the design requirements. S2.2.3, Rear Leg Main Tube Positioning: Hoist the rear leg main tube onto the assembly jig, use laser to correct the level of the rear leg main tube, and use a plumb bob to align the center line of the rear leg main tube's cylinder with the center line on the ground. Correct the slope of the rear leg main tube, cut off the excess material of the joining joint, and open the welding bevel. Use a clamp to fix the pre-assembled joining joint, and use baffles to fix the two sides of the rear leg main tube on the jig. S2.2.4 Welding and Machining: After pre-welding inspection, weld the closure of the rear leg main pipe. Welding should be carried out symmetrically on both sides simultaneously. After welding, re-measure the opening size of the lower end of the rear leg and the overall length size. The lower end opening deviation should be ±5mm, the overall length deviation should be ±5mm, and the levelness should be ±5mm. After overall leveling, machine and scribing should be carried out, and shaft holes should be machined. The rear leg outfitting platform should be installed intact, and any local damage should be repaired.

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