A large holed head lifting and overturning tool and overturning method

Abstract

The present application relates to heavy machinery assembly technical field, specifically relates to a kind of large hole head hoisting overturning tool and overturning method, tool includes the hoisting bar of passing through the inner hole of small end of head, hoisting bar both ends threaded section are respectively matched with first, second locking nut group, inner side nut group is equipped with spherical washer between head to automatically align center and lock force is evenly distributed, outside is equipped with flat washer, hoisting bar and inner hole wall are equipped with rubber protective layer, hoisting bar both ends are equipped with universal lifting lug;Overturning method uses main vice hook of crown block cooperation, through tool installation, near ground hoisting, is gradually overturned by three inspection points to realize that head is from big mouth upwards to big mouth downwards 180 ° smooth overturning.The present application uses the original small end hole of head as stress point, without welding lifting lug or additional hole, solve the problem that traditional overturning mode is easy to damage finish surface, stress concentration, attitude out of control, realize the high-efficiency overturning operation of large hole head zero damage, safe and controllable in nuclear power and other fields.

Description

Technical Field

[0001] This invention relates to the field of heavy machinery assembly technology, specifically to a lifting and turning fixture and method for large perforated heads, which is particularly suitable for solving the problem of non-destructive, efficient, and safe lifting and turning of large perforated heads in fields such as nuclear power and pressure vessels where surface quality requirements are high and there are no lifting points. Background Technology

[0002] In the field of nuclear power pressure vessels, perforated end caps are mostly irregularly shaped structures such as hemispherical and bowl-shaped, with strict surface quality requirements. In factories, it is often necessary to flip the end caps from a "larger opening up" position to a "larger opening down" position. These end caps are typically large in size and weight, exceeding 4.5 meters in diameter and weighing over 28 tons, but they lack lifting points on the surface, and welding lifting lugs or drilling are not permitted after precision machining. Furthermore, the end cap body has thin walls, is made of relatively soft material, and has poor rigidity, making it highly susceptible to surface scratches, indentations, and deformation during flipping. In addition, the small inner hole at the smaller end of the end cap makes it difficult to insert and install traditional lifting tools such as flexible lifting ropes, posing challenges for protection.

[0003] Existing methods for flipping this type of end cap include sand pit flipping, rope-assisted aerial flipping, or flipping mechanism flipping. Sand pit flipping requires operation in a sand pit, resulting in a harsh operating environment, poor controllability of the flipping process, and easy damage to the end cap surface. Rope-assisted aerial flipping presents high safety risks, difficulty in precisely controlling the flipping posture, and a high risk of collisions. Flipping mechanism flipping suffers from drawbacks such as complex equipment structure, high cost, and poor applicability.

[0004] Patent CN202410739363 discloses a method for flipping large nuclear power plant head-type parts using a split tooling. This method requires machining four process lifting holes in the remaining material at the head's port. These lifting holes, in conjunction with two hooks from an overhead crane, are used to achieve aerial flipping. A lifting column is inserted into the center hole of the head, and a locking bolt and nut are used to fix the column in the center hole. The locking bolt is radial, preventing the column from falling off. However, this technical solution still has the following shortcomings: (1) Its lifting scheme is only suitable for flipping during the machining process. After the head part is finished, the process lifting holes are removed, making it impossible to use them for flipping. The lifting column only serves a horizontal lifting function and cannot be used for flipping. (2) No protective layer is provided, and the lifting column directly contacts the inner wall of the head, posing a risk of scratching the surface of the inner hole.

[0005] Therefore, it is necessary to propose a turning tooling and process method for the turning problem of large perforated heads, so as to achieve a smooth 180° turning of the head and ensure that the turning process is safe, controllable, efficient and smooth, and free from scratches and collisions. Summary of the Invention

[0006] To solve the above-mentioned technical problems, this invention proposes a lifting and turning fixture and method for large perforated heads. The technical solution adopted by this invention is as follows: A lifting and turning fixture for a large perforated end cap includes a lifting rod that penetrates the inner hole of the small end of the end cap. The lifting rod has a threaded section that penetrates the inner hole of the small end of the end cap. The lifting rod has a first locking nut group and a second locking nut group that mate with the threaded section on the outer and inner sides of the end cap, respectively. A spherical washer is provided between the second locking nut group and the inner surface of the end cap. The spherical washer has a spherical contact surface and is used to automatically adjust the contact posture when the lifting rod or the upper surface of the end cap tilts. A flat washer is provided between the first locking nut group and the outer surface of the end cap. A rubber protective layer is provided between the outer circumferential surface of the lifting rod and the inner wall of the small end of the end cap. The end of the lifting rod facing the outer surface of the end cap is provided with a first universal lifting lug, and the other end is provided with a second universal lifting lug. Furthermore, the first locking nut group and the second locking nut group each include at least two locking nuts, and the first locking nut group and the second locking nut group are respectively locked and fixed by a double nut anti-loosening structure.

[0007] As a preferred embodiment, the frictional force generated by the locking preload of the first locking nut group and the second locking nut group is greater than the sliding component along the axial direction of the lifting rod caused by the weight of the end cap during the end cap flipping process.

[0008] As a preferred embodiment, the outer diameter of the lifting rod is smaller than the inner diameter of the small end of the end cap, and the length of the lifting rod is greater than the axial length of the inner diameter of the small end of the end cap, so that the two ends of the lifting rod extend out of the upper end face and the lower end face of the end cap, respectively.

[0009] As a preferred embodiment, the lifting rod is an integral structure, and the rubber protective layer is an elastic protective sleeve fitted onto the outer circumference of the lifting rod.

[0010] A method for lifting and turning large perforated heads, using the aforementioned lifting and turning fixture for large perforated heads, includes the following steps: S1. Installation fixture: First, place the end cap to be flipped stably on the ground by setting up a square box, pad, and protective layer from bottom to top. The shape of the protective layer corresponds to the end cap to support it. Then, insert the lifting rod through the inner hole of the small end of the end cap. Place the rubber protective layer between the outer circumference of the lifting rod and the inner wall of the small end of the end cap. Install the spherical gasket and the second locking nut assembly in sequence on the inner surface of the end cap and lock them. Install the flat gasket and the first locking nut assembly in sequence on one side of the outer surface of the end cap and lock them. Install the first universal lifting lug and the second universal lifting lug at both ends of the lifting rod. S2. Lifting preparation: First, connect the main hook of the crane to the second universal joint lug, and then connect the auxiliary hook of the crane to the first universal joint lug. Lift the end cap in an initial state with the large opening facing upward by the main hook and the auxiliary hook working together. S3. Flipping Operation: Through the coordinated lifting and lowering control of the main hook and the auxiliary hook, the end cap is gradually flipped around the axis of the lifting rod in a near-ground state. During the flipping process, the end cap is always above the protective layer until the end cap flips from the state with the large opening facing upwards to the state with the large opening facing downwards.

[0011] As a preferred embodiment, step S3 includes the following sub-steps: S301, keeping the main hook and the auxiliary hook raised synchronously, so that the end cap is off the ground to a first preset height, the main hook continues to raise, and the auxiliary hook stops raising or lowering, so that the end cap flips from the state with the large opening facing upward to the state of inclination; S302, when the end cap is flipped to the state of inclination, the flipping operation is paused, the posture of the end cap and the stress state of the tooling are observed, and the flipping is continued after confirming that there are no abnormalities; S303, the main hook continues to raise, and the auxiliary hook lowers in coordination, so that the end cap continues to flip from the state of inclination to the state with the large opening facing downward.

[0012] As a preferred embodiment, in step S301, the first preset height is such that the distance between the lower edge of the end cap and the ground does not exceed 500mm.

[0013] As a preferred embodiment, before step S2, the method further includes: pre-laying tires as a protective base on the ground of the flipping area, wherein the laying range of the protective base covers the projection area of ​​the end cap during the flipping process.

[0014] As a preferred option, during the flipping process in step S3, the flipping is paused when the head tilt angle reaches 45°, 90° and 135° respectively, to check the tooling connection status and the stress on the lifting rope.

[0015] The beneficial effects of this invention are: To address the shortcomings of existing technologies, this invention provides a lifting and turning fixture and method for large perforated heads. By optimizing the structural design and turning process, this invention achieves the following technical advantages: Firstly, this invention, through the structural design of a through-type lifting rod combined with spherical gaskets, flat gaskets, and locking nuts, uses the small end opening area of ​​the end cap body as the transmission path of the flipping driving force. It utilizes the frictional force generated by the pre-tightening force of the nuts to resist the slippage component force caused by the weight of the end cap during flipping, thus achieving a damage-free and rapid connection between the tooling and the end cap. This solves the technical problem of surface damage caused by welding lifting lugs or opening additional lifting points on the surface of the end cap in traditional flipping processes, and achieves zero-damage lifting and flipping of the workpiece surface.

[0016] Secondly, this invention provides a spherical washer between the second locking nut assembly and the inner surface of the end cap. The spherical contact surface of the washer automatically adjusts its contact posture when the upper surface of the lifting rod or the end cap is slightly tilted, ensuring uniform transmission of locking force and avoiding stress concentration. This solves the problem of uneven locking force distribution, local deformation, or loose connection caused by traditional flat washer when the contact surfaces are not parallel, thus improving the reliability and safety of tooling connection during the flipping process.

[0017] Thirdly, by setting a rubber protective layer between the outer circumferential surface of the lifting rod and the inner wall of the small end of the end cap, the present invention effectively isolates the direct contact between the lifting rod and the inner wall of the end cap, solves the problem of surface defects such as scratches and dents caused by relative displacement or pressure during the flipping process, and ensures the integrity of the surface quality of the end cap.

[0018] Fourth, this invention employs a comprehensive flipping process that combines coordinated control of the main and auxiliary hooks of the overhead crane, phased attitude adjustment, near-ground flipping, and a pre-set tire protection base in the flipping area. This ensures that the lower edge of the large port of the end cap remains in contact with the ground protection base during the flipping process, reducing the safety risks caused by sudden changes in workpiece attitude during the flipping process. It solves the problems of easy loss of control, easy collision, and the need for multiple people to assist in traditional aerial flipping methods. It has the advantages of convenient flipping operation, high safety, and zero damage to the workpiece. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 Schematic diagram of the head structure Figure 2 This is a schematic diagram showing the end cap rotated 180°. Figure 3 This is a schematic diagram of the structure of the present invention; Figure 4 This is a schematic diagram of the initial state before the end cap is flipped. Figure 5 This is a schematic diagram showing the installation of the flip-over fixture onto the end cap. Figure 6 This is a schematic diagram showing the end cap rotated 45°. Figure 7 This is a schematic diagram showing the end cap rotated 90°. Figure 8 A schematic diagram showing the end cap rotated 135°; Figure 9 A schematic diagram showing the end cap rotated 180°; Figure 10 A schematic diagram showing the placement of the end cap to the target workstation; In the diagram: 1. End cap, 2. Lifting rod, 3. Spherical gasket, 4. Rubber protective layer, 5. Flat gasket, 6. First locking nut assembly, 7. First universal lifting lug, 8. Second universal lifting lug, 9. Square box, 10. Pad block, 11. Protective layer, 12. Second locking nut assembly, 13. Main hook, 14. Auxiliary hook. Detailed Implementation

[0021] The present invention will now be described in detail through exemplary embodiments. However, it should be understood that, without further description, elements, structures, and features in one embodiment may be advantageously incorporated into other embodiments.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "a," "an," or "the," and similar words used in the specification and claims of this patent application do not express a limitation of quantity, but rather indicate the presence of at least one; terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, but do not exclude other elements or objects having the same function.

[0023] To more clearly describe the specific structural components and technological process of the lifting and turning fixture and method for this large perforated head, in conjunction with the attached... Figure 1 -Appendix Figure 10 This embodiment is described as follows: This embodiment takes a large perforated head 1 for a certain type of nuclear power pressure vessel as the object of the flipping. The head 1 has a "bowl-shaped" structure with an opening at the small end. The diameter is about 4.5 meters, the height is about 1.8 meters, the weight is about 28 tons, the material is low alloy steel, the surface has been finished with precision machining, the surface quality requirements are high, and welding of lifting lugs or opening of additional lifting points are not allowed.

[0024] The large perforated end cap lifting and turning fixture provided in this embodiment includes a lifting rod 2 that penetrates the inner hole of the small end of the end cap 1. The lifting rod 2 is made of high-strength alloy steel and has an overall cylindrical structure. Its outer diameter is smaller than the inner hole diameter of the small end of the end cap 1, with an appropriate gap between them to facilitate installation. The length of the lifting rod 2 is greater than the distance between the inner and outer surfaces of the end cap 1, so that both ends of the lifting rod 2 extend beyond the inner and outer surfaces of the end cap 1, respectively, facilitating the installation of universal lifting lugs and locking nut assemblies. The outer circumferential surface of the lifting rod 2 is provided with a threaded section that penetrates the end cap 1, and the threaded section covers the portions of the lifting rod 2 that extend beyond the end cap 1.

[0025] The lifting rod 2 has a first locking nut assembly 6 on the threaded section of one side of the outer surface of the end cap 1, which mates with the threaded section. A flat washer 5 is provided between the first locking nut assembly 6 and the outer surface of the end cap 1. The flat washer 5 is in close contact with the outer surface of the end cap 1 to increase the contact area, distribute the locking pressure, and protect the outer surface of the end cap 1. The lifting rod 2 has a second locking nut assembly 12 on the threaded section of one side of the inner surface of the end cap 1, which mates with the threaded section.

[0026] A spherical washer 3 is provided between the second locking nut assembly 12 and the inner surface of the end cap 1. The spherical washer 3 has a spherical contact surface, with one spherical side fitting against the inner surface of the end cap 1 and the flat side contacting the lower end face of the second locking nut assembly 12. It is used to automatically adjust the contact posture when the lifting rod 2 or the inner surface of the end cap 1 is slightly tilted, so as to ensure that the locking force is evenly transmitted and avoid stress concentration.

[0027] The first locking nut group 6 and the second locking nut group 12 each include at least two locking nuts, which are locked and fixed by a double nut anti-loosening structure to prevent the nuts from loosening due to vibration during the flipping process.

[0028] During the locking process, the frictional force generated by the locking preload of the first locking nut group 6 and the second locking nut group 12 is greater than the sliding component force along the axial direction of the lifting rod 2 caused by the weight of the end cap 1 during the flipping process, ensuring that there is no relative slippage between the tooling and the end cap 1 during the flipping process.

[0029] A rubber protective layer 4 is provided between the outer peripheral surface of the lifting rod 2 and the inner wall of the small end of the end cap 1. The rubber protective layer 4 is an elastic protective sleeve fitted on the outer peripheral surface of the lifting rod 2. It is made of oil-resistant and wear-resistant industrial rubber material. Its wall thickness is determined according to the gap between the outer diameter of the lifting rod 2 and the inner diameter of the small end of the end cap 1, so as to ensure that the rubber protective layer 4 can tightly fill the gap between the lifting rod 2 and the inner wall of the end cap 1 after installation, effectively isolating the direct contact between the metal parts.

[0030] In this embodiment, the rubber protective layer 4 is made of nitrile rubber, and its outer diameter is in a small interference fit with the inner diameter of the small end of the end cap 1, with an interference amount of 0.01mm to 0.05mm, which effectively isolates the direct contact between the lifting rod 2 and the inner wall of the end cap 1.

[0031] The lifting rod 2 has a first universal lifting lug 7 at one end facing the outer surface of the end cap 1, and a second universal lifting lug 8 at the other end. Both the first universal lifting lug 7 and the second universal lifting lug 8 can rotate freely 360° around the axis of the lifting rod 2 and swing within a certain angle range to ensure that the tooling is subjected to reasonable force and the end cap 1 is in a stable position during the lifting and turning process.

[0032] The method for lifting and turning large perforated heads provided in this embodiment uses the aforementioned lifting and turning fixture for large perforated heads, and specifically includes the following steps: S1. Installation fixtures: First, the operators prepare the site for the flipping operation. Multiple layers of waste tires are laid on the ground of the flipping area as a protective base. The protective base covers the projected area of ​​the end cap 1 during the flipping process to provide cushioning protection in case the end cap 1 slips accidentally. The tires are arranged in multiple staggered layers with a total thickness of not less than 200mm.

[0033] Subsequently, above the tire protection base, a square box 9, pad blocks 10, and a protective layer 11 are installed sequentially from bottom to top on the ground. The square box 9 is a steel rectangular frame structure used to provide a stable support base; the pad blocks 10 are made of wood or rubber and are placed on top of the square box 9 to adjust the support height and provide further cushioning; the protective layer 11 is made of soft materials such as rubber or polyurethane, and its shape corresponds to the outer contour of the end cap 1 to support the end cap 1 and protect its surface from damage. The operator uses an overhead crane to lift the end cap 1 to be turned over to the protective layer 11, so that the end cap 1 is placed stably on the protective layer 11 with its inner surface facing upwards.

[0034] Then, the operator inserts the lifting rod 2 through the inner hole of the small end of the end cap 1 from one side of the inner surface of the end cap 1, so that both ends of the lifting rod 2 extend out of the inner and outer surfaces of the end cap 1, respectively. Before inserting the lifting rod 2, the rubber protective layer 4 is first fitted onto the corresponding position on the outer circumference of the lifting rod 2, so that after the lifting rod 2 is inserted into the inner hole of the small end of the end cap 1, the rubber protective layer 4 is exactly located between the outer circumference of the lifting rod 2 and the inner wall of the small end of the end cap 1, which plays a role in isolation and protection. On one side of the inner surface of the end cap 1, the operator installs the spherical washer 3 and the second locking nut assembly 12 onto the threaded section of the lifting rod 2 in sequence, with the flat side of the spherical washer 3 facing the inner surface of the end cap 1 and the spherical side facing the second locking nut assembly 12.

[0035] Using a torque wrench, tighten the two locking nuts in the second locking nut group 12 in sequence according to the preset torque value to form a double nut anti-loosening structure. On one side of the outer surface of the end cap 1, the operator installs the flat washer 5 and the first locking nut group 6 onto the threaded section of the lifting rod 2 in sequence. The flat washer 5 is in close contact with the outer surface of the end cap 1. Similarly, use a torque wrench to tighten the two locking nuts in the first locking nut group 6 in sequence.

[0036] The specific tightening operation is as follows: the pre-tightening torque value is controlled within the range of 800 N·m to 1200 N·m. When tightening, first apply 50% pre-tightening torque to the first locking nut group 6, then apply 50% pre-tightening torque to the second locking nut group 12, and then tighten the first locking nut group 6 and the second locking nut group 12 to the full pre-tightening torque in sequence. Finally, tighten the anti-loosening nuts in each locking nut group.

[0037] After locking, the operator checks whether the lifting rod 2 is centered, whether each locking nut assembly is tightened in place, and whether the rubber protective layer 4 is in the correct position. After confirming that everything is correct, the first universal lifting lug 7 and the second universal lifting lug 8 are installed at both ends of the lifting rod 2, respectively. The first universal lifting lug 7 is installed at the end of the lifting rod 2 facing the outer surface of the end cap 1, and the second universal lifting lug 8 is installed at the other end of the lifting rod 2. The rotation flexibility of the universal lifting lugs is then checked.

[0038] S2. Lifting preparation: The operator directs the crane operator to move the main hook 13 above the end cap 1 and reliably connect the sling of the main hook 13 to the second universal joint 8. Then, the crane operator moves the auxiliary hook 14 below the end cap 1 and reliably connects the sling of the auxiliary hook 14 to the first universal joint 7. The operator checks the connection status of the slings of the main hook 13 and auxiliary hook 14, confirming that the slings are free of kinks, the joints rotate freely, and all connection points are secure and reliable. Then, the operator issues a lifting command, and the crane operator, using the main hook 13 and auxiliary hook 14 in coordination, lifts the end cap 1 slowly away from the protective layer 11, maintaining the end cap 1 in its initial state with the large opening facing upwards. The lifting height of the main hook 13 and auxiliary hook 14 is adjusted so that the distance between the lower edge of the large opening of the end cap 1 and the ground does not exceed 500mm, entering the near-ground flipping preparation state.

[0039] S3, Flip Operation: The operator directs the crane operator to control the lifting of the main hook 13 and the auxiliary hook 14 in a coordinated manner, so that the end cap 1 gradually rotates around the axis of the lifting rod 2 while in a near-ground state.

[0040] The specific sub-steps are as follows: S301. The crane operator maintains synchronized lifting of the main hook 13 and auxiliary hook 14, raising the end cap 1 to a first preset height. The first preset height ensures that the distance between the lower edge of the large end cap 1 and the ground does not exceed 500mm. Subsequently, the main hook 13 continues to lift slowly, while the auxiliary hook 14 stops lifting or lowers in coordination, gradually flipping the end cap 1 from a position with the large opening facing upwards to an inclined position. During this process, the operator continuously observes the changes in the posture of the end cap 1 and the stress on various components of the tooling.

[0041] S302. When the end cap 1 is rotated to an inclined state, i.e., the tilt angle of the end cap 1 reaches approximately 45°, the operator issues a pause command, and the crane operator stops all operations. The operator carefully observes whether the overall posture of the end cap 1 is stable, whether the lifting rod 2 has shifted, whether the second locking nut group 12 and the first locking nut group 6 are loose, whether the contact posture of the spherical gasket 3 is normal, whether the rubber protective layer 4 has shifted, whether the rotation of the first universal lifting lug 7 and the second universal lifting lug 8 is smooth, and whether the tension on the lifting cable is uniform. After confirming that there are no abnormalities, the operator issues a command to continue rotating.

[0042] S303: The crane operator controls the main hook 13 to continue lifting and the auxiliary hook 14 to cooperate in lowering, causing the end cap 1 to continue flipping from its tilted state. When the tilt angle of the end cap 1 reaches approximately 90°, the operator issues a pause command again to conduct a second attitude observation point check, the content of which is the same as in S302. After confirming that there are no abnormalities, the flipping continues. When the tilt angle of the end cap 1 reaches approximately 135°, the operator conducts a third attitude observation point check. After confirming that there are no abnormalities, the crane operator controls the main hook 13 to continue lifting and the auxiliary hook 14 to continue lowering until the end cap 1 is completely flipped from a position with the large opening facing upwards to a position with the large opening facing downwards. Throughout the flipping process, the lower edge of the large opening of the end cap 1 always maintains contact with or a very small gap from the protective layer 11, which corresponds to the shape of the end cap 1. The protective layer 11 provides continuous support and protection for the end cap 1.

[0043] After the rotation is completed, the operator directs the crane operator to place the end cap 1 stably in the predetermined position. Then, the fixture is disassembled in the reverse order of installation: first, the second universal joint lug 8 and the first universal joint lug 7 are removed; then, the second locking nut group 12 and the first locking nut group 6 are loosened in sequence; the spherical washer 3 and the flat washer 5 are removed; finally, the lifting rod 2 along with the rubber protective layer 4 is pulled out from the inner hole of the small end of the end cap 1. After disassembly, all parts of the fixture are cleaned, inspected, and properly stored for reuse in subsequent similar end cap rotation operations.

[0044] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.

Claims

1. A lifting and turning fixture for large perforated heads, characterized in that, The device includes a lifting rod (2) that penetrates the inner hole of the small end of the end cap (1). The lifting rod (2) has a threaded section that penetrates the inner hole of the small end of the end cap (1). The lifting rod (2) has a first locking nut group (6) and a second locking nut group (12) that mate with the threaded section on the outer and inner sides of the end cap (1), respectively. A spherical washer (3) is provided between the second locking nut group (12) and the inner surface of the end cap (1). The spherical washer (3) has a spherical contact surface and is used to automatically adjust the contact posture when the lifting rod (2) or the end cap (1) tilts. A flat washer (5) is provided between the first locking nut group (6) and the outer surface of the end cap (1). A rubber protective layer (4) is provided between the outer circumferential surface of the lifting rod (2) and the inner wall of the small end of the end cap (1). The lifting rod (2) is provided with a first universal lifting lug (7) at one end facing the outer surface of the end cap (1) and a second universal lifting lug (8) at the other end.

2. The lifting and turning fixture for a large perforated end cap according to claim 1, characterized in that, The first locking nut group (6) and the second locking nut group (12) each include at least two locking nuts, and the first locking nut group (6) and the second locking nut group (12) are respectively locked and fixed by a double nut anti-loosening structure.

3. The lifting and turning fixture for a large perforated end cap according to claim 1, characterized in that, The frictional force generated by the locking preload of the first locking nut group (6) and the second locking nut group (12) is greater than the sliding component force along the axial direction of the lifting rod (2) caused by the weight of the end cap (1) during the flipping process.

4. The lifting and turning fixture for a large perforated end cap according to claim 1, characterized in that, The outer diameter of the lifting rod (2) is smaller than the inner diameter of the end cap (1), and the length of the lifting rod (2) is greater than the axial length of the inner hole at the small end of the end cap (1), so that the two ends of the lifting rod (2) extend out of the upper and lower surfaces of the end cap (1), respectively.

5. The lifting and turning fixture for a large perforated end cap according to claim 1, characterized in that, The rubber protective layer (4) is an elastic protective sleeve fitted on the outer periphery of the hanging rod (2).

6. A method for lifting and turning a large perforated end cap, characterized in that, The large perforated head lifting and turning fixture as described in any one of claims 1 to 5 includes the following steps: S1. Installation tooling: First, place the end cap (1) to be flipped on the ground by setting a square box (9), a pad (10) and a protective layer (11) from bottom to top. The shape of the protective layer (11) corresponds to the end cap (1) to support the end cap (1). Then, insert the lifting rod (2) through the inner hole of the small end of the end cap (1). Set the rubber protective layer (4) between the outer circumference of the lifting rod (2) and the inner wall of the small end of the end cap (1). Install the spherical gasket (3) and the second locking nut group (12) on the inner surface of the end cap (1) in sequence and lock them. Install the flat gasket (5) and the first locking nut group (6) on one side of the outer surface of the end cap (1) in sequence and lock them. Install the first universal lifting lug (7) and the second universal lifting lug (8) on both ends of the lifting rod (2). S2. Lifting preparation: First, connect the main hook (13) of the crane to the second universal lug (8), and then connect the auxiliary hook (14) of the crane to the first universal lug (7). The main hook (13) and the auxiliary hook (14) work together to lift the end cap (1) in the initial state with the large opening facing upward. S3, Flipping Operation: Through the coordinated lifting control of the main hook (13) and the auxiliary hook (14), the end cap (1) is flipped gradually around the axis of the lifting rod (2) in a near-ground state. During the flipping process, the end cap (1) is always above the protective layer (11) until the end cap (1) flips from the state with the large opening facing up to the state with the large opening facing down.

7. A method for lifting and turning a large perforated end cap according to claim 6, characterized in that, Step S3 includes the following sub-steps: S301. Keep the main hook (13) and the auxiliary hook (14) raised synchronously, so that the end cap (1) is off the ground to the first preset height. Then, the main hook (13) continues to be raised and the auxiliary hook (14) stops being raised or lowered, so that the end cap (1) is flipped from the state with the large opening facing upward to the tilted state. S302. When the end cap (1) is flipped to an inclined state, pause the flipping operation, observe the posture of the end cap (1) and the stress state of the tooling, and continue flipping after confirming that there is no abnormality. S303, the main hook (13) continues to lift and the auxiliary hook (14) cooperates to lower, so that the end cap (1) continues to flip from the inclined state to the state with the large opening facing down.

8. A method for lifting and turning a large perforated end cap according to claim 7, characterized in that, In step S301, the first preset height is such that the distance between the lower edge of the large port of the end cap (1) and the ground does not exceed 500mm.

9. A method for lifting and turning a large perforated end cap according to claim 6, characterized in that, Before step S2, the method further includes: laying tires as a protective base on the ground of the flipping area, the range of which covers the projection area of ​​the end cap (1) during the flipping process.

10. A method for lifting and turning a large perforated end cap according to claim 6, characterized in that, During the flipping process in step S3, the flipping is paused when the tilt angle of the end cap (1) reaches 45°, 90° and 135° respectively, and the tooling connection status and the stress of the lifting rope are checked.

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