A lifting and turning method without welding lugs

Abstract

A method for lifting and turning steel structures without welded lifting lugs involves CNC-controlled or manual drilling of permanent openings in the vertical plates or webs of T-beams of the steel structure, with the positions and number matching the crane's lifting points. Permanent reinforcing plates are welded around these openings for reinforcement. The opening dimensions must meet the pin assembly requirements of the turning connection device, and the reinforcing plate dimensions must meet the assembly requirements of the lifting and turning device and comply with safety regulations. After the tooling is connected to the permanent openings in the structure, during lifting and turning at 180°, the load-bearing connecting plate and the free edge of the T-beam are in line contact, facilitating the bearing of line load pressure and thus optimizing the overall stress distribution of the tooling. This method completely eliminates lengthy and high-risk additional processes such as lifting lug installation, flaw detection, cutting, grinding, and base material repair. Preparation time before lifting and turning and post-turning processing time are reduced by more than 80%, significantly improving production line efficiency.

Description

Technical Field

[0001] This invention belongs to the field of marine shipbuilding and design, and specifically relates to a lifting and turning method without welding lugs. Background Technology

[0002] A semi-three-dimensional structure is a sub-section of a double-bottom or double-hull section of a ship. It is usually formed by splicing inner bottom plates or inner hull plates and then welding T-beams. After being overturned using a crane, the semi-three-dimensional section is assembled with the outer bottom or outer hull plates to form a complete section. To achieve the overall overturning of a large semi-three-dimensional steel structure, the common method is to weld multiple special overturning lifting lugs onto the structure. After overturning, the lifting lugs are removed and the base material and structure are repaired.

[0003] The traditional lifting and turning process using lifting lugs has the following drawbacks: 1. Complex procedures: A single turning process involves numerous steps, including assembling lifting lugs and temporary reinforcements, welding, post-weld flaw detection, hoisting and turning, cutting / gouging, grinding of the base material, and repair of plate edges. This takes up a significant amount of time on the production line, slowing down the overall construction pace.

[0004] 2. High Costs: Based on annual production plan statistics, more than 8,500 C-shaped lifting lugs and their temporary reinforcements are used annually for semi-three-dimensional turning systems, with a lug reuse rate of less than 10%, resulting in material costs of approximately 2 million yuan per year. Simultaneously, the labor costs for lug assembly, welding, and repair are also substantial, with total annual manual labor hours exceeding 32,000 hours.

[0005] 3. Potential quality hazards: Welding the lifting lugs poses a risk of damaging the base material, and there are also quality risks such as damaging the original bevel and the short ruler of the T-beam after cutting.

[0006] 4. High labor intensity: It requires multiple handling, welding, cutting and grinding operations. The complicated process and heavy physical labor put a heavy burden on workers and increase safety hazards. Summary of the Invention

[0007] To address the above problems, this invention provides a lifting and turning method without welded lifting lugs, the technical solution of which is as follows: A method for lifting and turning a ship without welded lifting lugs is disclosed. At both ends of a ship sub-section, there are main turning holes and auxiliary turning holes, forming main turning lifting points and auxiliary turning lifting points. The main turning holes are permanent openings. The main turning holes are made on the webs of two adjacent T-beams at one end of the sub-section, forming a pair of two main turning holes. The auxiliary turning holes are made on the webs of the T-beams at the other end of the sub-section, with a gap between them.

[0008] Reinforcing plates are welded onto the main turning hole and the auxiliary turning hole, and the opening radius of the reinforcing plates is larger than that of the main turning hole and the auxiliary turning hole.

[0009] During hoisting, hoisting clamps are fixed to the main and auxiliary turning holes. The hoisting clamps include a clamping mechanism and a load-bearing connecting plate. The clamping mechanism has two identical plates. One end of each plate clamps the main turning hole and is hinged to it via a pin. The other end of each plate clamps the load-bearing connecting plate and is hinged to it via a pin. The other end of the load-bearing connecting plate is hinged to the crane shackle.

[0010] The specific process of turning over is as follows: S1: Lifting and lifting conditions. The sub-section is kept parallel to the horizontal plane. The main turning lifting point and the auxiliary turning lifting point are under force at the same time. The load-bearing connecting plate is erected and keeps in line contact with the edge of the web of the T-beam. The crane lifts the ship sub-section from the jig to the turning site. After the hook touches the ground, it is ready to be turned.

[0011] S2: Disconnect the lifting clamp on the auxiliary turning point from the sub-segment, but do not disconnect the lifting clamp from the crane hook. The main turning point is connected to the hoisting clamp. The main turning point is slowly lifted upwards, while the other end of the sub-segment remains on the ground to form a rotation axis. The sub-segment then begins to turn.

[0012] S3: When one end of the sub-segment is lifted upwards and forms an angle with the ground, the bearing connecting plate stands upright and separates from the edge of the T-profile web. Continue to lift the main turning point to keep the other end of the sub-segment on the ground and turning it over.

[0013] S4: When the sub-segment is turned to 90°, the sub-segment is grounded and rolled over. The main turning point is raised to lift the sub-segment off the ground by about 500mm. The auxiliary turning point of the gantry crane is used to reinstall the lifting clamps on the other side of the sub-segment.

[0014] S5: After the auxiliary turning point is equipped with the lifting clamp, the main turning point and the auxiliary turning point work together to turn the section to 180°. At this time, all load-bearing connecting plates are erected and maintain line contact with the edge of the web of the T-beam.

[0015] S6: After completing the assembly of the sub-section with the outer bottom plate or outer shell plate, and after the sealing welding is completed, loosen the lifting clamps on the main turning point and the auxiliary turning point, remove and recycle them for reuse.

[0016] Furthermore, in the above-mentioned method for hoisting and turning over a large steel structure without welded lifting lugs, the opening diameter of the main turning hole and the auxiliary turning hole is 3-4 mm larger than the pin diameter of the connecting device.

[0017] Furthermore, the above-mentioned method for hoisting and turning large steel structures without welded lifting lugs is further described in which the ship sub-section is a sub-section of a double bottom or double hull section of a ship.

[0018] Furthermore, in the above-mentioned method for hoisting and turning large steel structures without welded lifting lugs, both ends of the plates and the load-bearing connecting plates are rounded.

[0019] Furthermore, in the above-mentioned method for hoisting and turning over a large steel structure without welded lifting lugs, the distance between the two pairs of main turning holes is greater than the distance between the two auxiliary turning holes.

[0020] Furthermore, the above-mentioned method for hoisting and turning large steel structures without welded lifting lugs allows for the weight of ship sub-sections to be less than 145t.

[0021] The beneficial effects of this invention are: 1. Significantly streamlined processes, resulting in a leap in efficiency: (1) The lengthy and high-risk additional processes such as lifting ring installation (2h / piece), flaw detection (0.5h / piece), cutting (1.5h / piece), grinding and base material repair (2h / piece) have been completely eliminated. The preparation time before lifting and turning and the processing time after turning are reduced by more than 80%, which greatly improves the production efficiency of the assembly line; (2) The structural openings and reinforced web plates are permanent parts that comply with structural specifications and are permanently retained with the approval of the shipowner and ship inspection authorities. They are reflected in the hull assembly drawings in advance during the production design stage and are opened during the steel-making CNC stage. The design process is moved forward, which greatly saves the production cycle. (3) The semi-three-dimensional turning process is eliminated from the segmented hoisting scheme drawings (which is expected to save 35% of the design time of the relevant segmented hoisting scheme) and replaced by a general turning process (which will be formed into a factory standard later), which can greatly save the design cycle.

[0022] 2. Significant cost restructuring yields substantial benefits: (1) Direct material savings: Complete elimination of consumption of lifting rings, reinforcements and welding materials. Taking the T300K as an example, a single ship will save 420 C-type lifting rings (accounting for 8% of the total lifting ring usage), 140 triangular plate reinforcements, and 130m of channel steel. Based on the annual production plan, it is estimated that material costs can be saved by RMB 1.4 million per year.

[0023] (2) Reduced labor costs: Significantly reduces the high-intensity working time and personnel input for welding, cutting, grinding and other trades, saving 32,000 hours of construction time per year (approximately RMB 1.6 million).

[0024] (3) Improved efficiency and cost: Significantly improves the production efficiency of the segmented assembly line and speeds up the production line cycle! 3. Improved safety and reduced workload: (1) It completely eliminates the long-term welding, high-altitude cutting and grinding operations, thus eliminating the relevant safety risks from the source.

[0025] (2) The lifting fixture weighs about 32kg. In actual use, it can be pre-installed in the production line. According to the first test observation, the total time to complete the single-section lifting point arrangement is less than 10 minutes. The labor intensity of workers is significantly reduced, the operation is safer, more labor-saving and more humane, and the workers' satisfaction is greatly improved.

[0026] 4. Strengthening the foundation of quality and promoting green manufacturing: (1) It avoids the quality risks caused by the heat-affected zone damage, deformation or subsequent repair and grinding of the base material due to welding of the lifting ring, as well as the quality risks of damaging the original bevel and T-beam short ruler after cutting.

[0027] (2) It reduces welding fumes, cutting noise and solid waste (welding slag, waste lifting rings), which is more in line with the concept of green shipbuilding. Attached Figure Description

[0028] Figure 1 This is a structural diagram of a ship's subsection; Figure 2 This is a schematic diagram of the main structure of the hoisting clamp; Figure 3 This is a schematic diagram of the plate and connecting block structure; Figure 4 This is a schematic diagram showing the lifting angle when the sub-segments are in a horizontal position. Figure 5 This is a schematic diagram showing the state of the hoisting fixture when the sub-segment forms an angle with the ground. Figures 6-9 This is a diagram illustrating the segmented rolling process; Among them, 1-plate, 2-main turning hole, 3-secondary turning hole, 4-pin, 5-bearing connecting plate, 6-reinforcing plate, 7-T-beam web, 8-crane shackle. Detailed Implementation

[0029] The invention will be further described with reference to the accompanying drawings.

[0030] A lifting and turning method without welded lifting lugs is proposed for lifting and turning sub-sections of ships weighing up to 145t. Figure 1 As shown, each end of the ship's sub-section has a main turning hole and a secondary turning hole, forming a main turning lifting point and a secondary turning lifting point. Both the main and secondary turning holes are permanent openings. The main turning holes are made on the webs of two adjacent T-beams at one end of the sub-section; two adjacent main turning holes form a pair, and there are two pairs in total. The secondary turning holes are made on the webs of the T-beams at the other end of the sub-section; there are two secondary turning holes with a gap between them.

[0031] Reinforcing plates are welded onto the main turning hole and the auxiliary turning hole, and the opening radius of the reinforcing plates is larger than that of the main turning hole and the auxiliary turning hole.

[0032] During hoisting, hoisting clamps are fixed on the main and auxiliary turning holes, such as... Figure 2 , 3 As shown, the lifting fixture includes a clamping mechanism and a load-bearing connecting plate. The clamping mechanism has two identical plates. One end of each plate clamps the main turning hole and is hinged to it via a pin. The other end of each plate clamps the load-bearing connecting plate and is hinged to it via a pin. The other end of the load-bearing connecting plate is hinged to the crane shackle 8.

[0033] like Figures 6-9 As shown, the specific process of turning over is as follows: S1: Lifting and jig removal conditions. The sub-section remains parallel to the horizontal plane. The main and auxiliary turning lifting points are simultaneously stressed. The load-bearing connecting plate is upright and maintains line contact with the edge of the T-beam web. Figure 4 As shown, the crane lifts the ship's sub-sections horizontally from the jig to the turning site, and prepares to turn them over after the hooks touch the ground; S2: Disconnect the lifting clamp on the auxiliary turning point from the sub-section, but do not disconnect the lifting clamp from the crane hook. The main turning point is connected to the hoisting clamp. The main turning point is slowly lifted upwards, while the other end of the sub-section remains on the ground to form a rotating shaft. The sub-section begins to turn. S3: When one end of the sub-segment is lifted upwards, forming an angle with the ground, such as Figure 5 As shown, the load-bearing connecting plate is erected and separated from the edge of the T-profile web. The main turning point is raised to keep the other end of the sub-section on the ground and turning. S4: When the sub-segment is turned to 90°, the rolling and landing of the sub-segment is completed. The main turning point is raised to lift the sub-segment off the ground by about 500mm. The auxiliary turning point of the gantry crane is used to reinstall the lifting clamps on the other side of the sub-segment. S5: After the auxiliary turning point is equipped with the lifting clamp, the main turning point and the auxiliary turning point work together to turn the section to 180°. At this time, all load-bearing connecting plates are upright and in line contact with the edge of the web of the T-beam. S6: After completing the assembly of the sub-section with the outer bottom plate or outer shell plate, and after the sealing welding is completed, loosen the lifting clamps on the main turning point and the auxiliary turning point, remove and recycle them for reuse.

[0034] A reusable, non-welded hoisting and turning device was developed to replace the existing welded lifting rings. This hoisting and turning device has the following technical features: (1) The main fixing mechanism is a double-layer main connecting steel plate with a straight long side and a rounded short side. It has holes at both ends and is not welded.

[0035] (2) A secondary rotating mechanism is installed on one side between the double-layer main connecting steel plates; (3) The secondary rotating mechanism has a sandwich structure, with a load-bearing connecting plate in the middle and reinforcing web plates on both sides. The web plates are connected to the load-bearing plate by welding. (4) The double-layer main connecting steel plate will be subjected to steel compression during hoisting, so high-strength steel is used.

[0036] (5) The two ends of the secondary rotating mechanism are perforated. When in use, one end is perforated to connect with the main fixed mechanism, and the other end is perforated to connect with the crane shackle.

[0037] (6) Use double pins for operation. One pin fixes the load-bearing connecting plate to the suspended object, and the other pin connects to the secondary rotating mechanism.

[0038] (7) High-strength pin and anti-loosening nut design.

[0039] The device possesses certain tensile, compressive, and shear strengths, and can also withstand lateral forces.

[0040] (9) The self-weight of the turning device is similar to that of the turning ring, making it easy to load and unload.

[0041] (10) The advantages of using a double-pin shaft in the turning device are: ① When the semi-three-dimensional segment is lowered or lifted (turning at 0 degrees) and when it is turned at 180 degrees, the secondary rotation mechanism will always ensure that one side is in line contact with the free edge of the web of the T-section, rather than point contact, so that stress concentration does not occur at the contact position of the tooling and the T-section structure, and the strength meets the requirements. ② Due to the existence of the secondary rotation mechanism, when the semi-three-dimensional segment is lowered or lifted (turning at 0 degrees) and when it is turned at 180 degrees, the height of the connection point between the device and the crane shackle is higher than the position of the center of gravity of the semi-three-dimensional segment, so as to ensure that the lifting process is more stable and there will be no adverse phenomena such as shaking. ③ The device can be installed / disassembled as a whole or separately during assembly and disassembly, which is more flexible and convenient, and the freedom of parts replacement is higher. ④ Due to the existence of the secondary rotation mechanism, the position of the crane shackle will be further away from the T-shaped panel (0° working condition) and the semi-three-dimensional outer base plate (180° working condition), thereby further avoiding the risk of interference between the crane wire rope connected to the shackle and the T-shaped panel or outer base plate.

[0042] (11) When the device is assembled with the T-shaped web opening, it optimizes the stress of the tooling as a whole during semi-three-dimensional segmented tire removal or tire lifting (0-degree turning angle condition) and 180-degree turning angle condition.

[0043] (12) The diameter of the connecting shaft for assembling the device with the opening should be 3-4 mm smaller than the diameter of the opening to facilitate assembly and ensure Hertzian contact stress.

[0044] This system achieves the lifting and turning of semi-three-dimensional large steel structures by completely replacing traditional welded lifting lugs with a non-welded combination of a turning device and permanent holes. It is the first time in a domestic shipyard that a semi-three-dimensional segmented turning operation without lifting lugs has been realized. This significantly reduces the cost of manufacturing lifting lugs, eliminates a series of construction processes such as lug installation, welding, cutting, and grinding, avoids related safety hazards and quality problems, and greatly improves the efficiency of lifting operations.

Claims

1. A lifting and turning method without welded lifting lugs, characterized in that, The ship's sub-sections are equipped with main and auxiliary turning holes at both ends, forming main and auxiliary turning lifting points. The main and auxiliary turning holes are permanent openings. The main turning holes are made on the webs of two adjacent T-beams at one end of the sub-section, and there are two pairs of two adjacent main turning holes. The auxiliary turning holes are made on the webs of the T-beams at the other end of the sub-section, and there are two auxiliary turning holes with a gap between them. Reinforcing plates are welded onto the main turning hole and the auxiliary turning hole, and the opening radius of the reinforcing plates is larger than that of the main turning hole and the auxiliary turning hole. During hoisting, hoisting clamps are fixed on the main and auxiliary turning holes. The hoisting clamps include a clamping mechanism and a load-bearing connecting plate. The clamping mechanism has two identical plates. One end of the two plates clamps the main turning hole and is hinged to the main turning hole by a pin. The other end of the two plates clamps the load-bearing connecting plate and is hinged to the load-bearing connecting plate by a pin. The other end of the load-bearing connecting plate is hinged to the crane shackle. The specific process of turning over is as follows: S1: Lifting and lifting conditions, the sub-section is kept parallel to the horizontal plane, the main turning lifting point and the auxiliary turning lifting point are under force at the same time, the load-bearing connecting plate is erected and keeps in line contact with the edge of the web of the T-beam. The crane lifts the ship sub-section from the frame to the turning site, and after the hook touches the ground, it is ready to be turned. S2: Disconnect the lifting clamp on the auxiliary turning point from the sub-section, but do not disconnect the lifting clamp from the crane hook. The main turning point is connected to the hoisting clamp. The main turning point is slowly lifted upwards, while the other end of the sub-section remains on the ground to form a rotating shaft. The sub-section begins to turn. S3: When one end of the sub-segment is lifted upwards and forms an angle with the ground, the bearing connecting plate stands upright and separates from the edge of the T-profile web plate. Continue to lift the main turning point to keep the other end of the sub-segment on the ground and turning it over. S4: When the sub-segment is turned to 90°, the rolling and landing of the sub-segment is completed. The main turning point is raised to lift the sub-segment off the ground by about 500mm. The auxiliary turning point of the gantry crane is used to reinstall the lifting clamps on the other side of the sub-segment. S5: After the auxiliary turning point is equipped with the lifting clamp, the main turning point and the auxiliary turning point work together to turn the section to 180°. At this time, all load-bearing connecting plates are upright and in line contact with the edge of the web of the T-beam. S6: After completing the assembly of the sub-section with the outer bottom plate or outer shell plate, and after the sealing welding is completed, loosen the lifting clamps on the main turning point and the auxiliary turning point, remove and recycle them for reuse.

2. The lifting and turning method without welding lugs according to claim 1, characterized in that, The opening diameter of the main turning hole and the auxiliary turning hole is 3-4 mm larger than the diameter of the pin of the connecting device.

3. The lifting and turning method without welding lugs according to claim 1, characterized in that, A ship subsection is a subsection of a ship with a double bottom or double hull.

4. The lifting and turning method without welding lugs according to claim 1, characterized in that, Both ends of the plate and the load-bearing connecting plate are rounded.

5. The lifting and turning method without welded lifting lugs according to claim 1, characterized in that, The distance between the two pairs of main turning holes is greater than the distance between the two auxiliary turning holes.

6. The lifting and turning method without welded lifting lugs according to claim 1, characterized in that, The weight of the ship's subsection is less than 145t.

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