Horizontal hoisting tool for blades of wind generating set
By introducing a movable adjustment device and a multi-stage hydraulic cylinder into the horizontal lifting fixture for wind turbine blades, combined with lubrication and buffering devices, the problem of insufficient adaptability of traditional lifting fixtures has been solved, enabling multi-angle adjustment and stable lifting, thus improving lifting efficiency and safety.
Patent Information
- Application Number
- CN202520497978.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2026-01-23
- Estimated Expiration
- 2035-03-20
AI Technical Summary
Traditional horizontal hoisting fixtures for wind turbine blades are difficult to adapt to multi-angle adjustments for different blade types, resulting in insufficient flexibility and practicality in hoisting operations.
The device employs a movable adjustment mechanism in conjunction with a multi-stage hydraulic cylinder. A rotary motor drives the lead screw and hydraulic cylinder to adjust the clamping device at multiple angles. Combined with a lubrication device and cushioning cotton, the stability and safety of the equipment are improved.
This improved the flexibility and practicality of blade hoisting, ensured the stability and safety of the hoisting process, and reduced equipment wear and manual intervention.
Smart Images
Figure CN223823163U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to wind power generation technical field especially relates to a horizontal hoisting frock of wind turbine unit blade. BACKGROUND
[0002] The blade of wind turbine unit is one of the core components of the whole wind power generation system, and its design and manufacture directly affect the efficiency, reliability and cost of wind power generation, and the hoisting of wind turbine unit blade is a key link in wind farm construction and maintenance.
[0003] The conventional horizontal hoisting frock of wind turbine unit blade is not easy to adjust and adapt to different blade types in multiple angles when in use, which affects the normal blade hoisting work progress and reduces the flexibility and practicality of blade hoisting work, therefore, the technical personnel in the field provides a horizontal hoisting frock of wind turbine unit blade to solve the problems in the above background technology. UTILITY MODEL CONTENT
[0004] The utility model discloses a horizontal hoisting frock of wind turbine unit blade to solve the problems in the above background technology, which realizes multiple angle adjustment through the cooperation of the moving adjustment device and the multi-section hydraulic cylinder, thereby improving the flexibility and practicality of blade hoisting work.
[0005] To achieve the above object, the utility model provides the following technical scheme: a horizontal hoisting frock of wind turbine unit blade, including hoisting box and two square grooves, two square grooves are arranged respectively at the center of both sides of hoisting box, and the center of the inner wall of hoisting box is equipped with moving adjustment device;
[0006] The moving adjustment device includes two horizontal moving assemblies and two front and back moving assemblies, two horizontal moving assemblies are arranged respectively at the center of the lower end of the inner side wall of hoisting box, and the center of the upper end surface of two horizontal moving assemblies is equipped with moving frame, and two front and back moving assemblies are arranged respectively at the inner center of two moving frames;
[0007] The horizontal moving assembly includes first rotary motor, first rotary motor is arranged at the center of the lower end of the inner wall of hoisting box, and the center of the lower end of the inner wall of hoisting box is equipped with first screw rod, the one end of first screw rod is equipped with connector, the one end of connector is equipped with second screw rod, and second screw rod is rotatably connected between the other inner side wall of hoisting box through bearing, and first screw rod and second screw rod are respectively screwed with moving frame;
[0008] Through the technical scheme, the first screw rod is driven to rotate by the first rotary motor, the connector and the second screw rod are driven to rotate by the first screw rod, and the first screw rod and the second screw rod are respectively threadedly sleeved with the moving frame, so that the moving frame can be driven to move horizontally, the size and type of the blade can be adjusted, and the moving frame can be moved and adjusted according to the target area.
[0009] Further, the front-back moving assembly comprises a second rotary motor, the second rotary motor is arranged at the center of the rear inner wall of the moving frame, a third screw rod is arranged at the output end of the second rotary motor, one end of the third screw rod is rotatably connected with the front inner wall of the moving frame through a bearing, and a moving block is threadedly sleeved with the outer center of the third screw rod.
[0010] Through the technical scheme, the third screw rod is driven to rotate by the second rotary motor, so that the moving block can be moved and adjusted forward and backward, the horizontal and moving adjustment of the clamping device can be realized, multi-angle adjustment can be realized, the size and type of the blade can be adjusted according to the different size and type of the blade, and the flexibility and practicability of the blade hoisting work are improved.
[0011] Further, lubricating devices are arranged at the centers of the upper end faces of the two moving blocks at the lower position and the lower end faces of the two moving blocks at the upper position, the lubricating device comprises an oil storage tank, the oil storage tank is arranged at the center of the upper end face of the moving block, an oil injection nozzle is arranged at the center of the upper end face of the oil storage tank, a micro pump is arranged at the center of the lower end face of the oil storage tank, the input end of the micro pump penetrates through the lower end face of the oil storage tank and reaches the inner wall of the oil storage tank, a connecting channel is arranged at the output end of the micro pump, and the output end of the connecting channel penetrates through the moving block and reaches the inside of the moving block.
[0012] Through the technical scheme, the lubricating oil is introduced into the inside of the oil storage tank through the oil injection nozzle, the lubricating oil is brought into the connecting channel by controlling the closing and starting of the micro pump, and then the lubricating oil is delivered to the inside of the moving block, so that the surface of the third screw rod can be lubricated, the abrasion during movement is reduced, the operation stability of the equipment is ensured, the failure rate is reduced, the hoisting process is ensured to be smoothly performed, and the lubrication process is automated, and the manual intervention is reduced.
[0013] Further, storage tanks are arranged at the centers of the inner walls of the two moving frames at the upper position and the inner walls of the two moving frames at the lower position, oil outlet holes are arranged at the centers of the inner walls of the two storage tanks at the upper position and the inner walls of the two storage tanks at the lower position, and eight oil outlet holes penetrate through the inner walls of the four moving frames and reach the insides of the four moving frames.
[0014] Through the technical scheme, the third screw rod surface lubricating oil drops into the storage tank, and then the lubricating oil is transported into the moving frame through the oil outlet, so that the first screw rod and the second screw rod are lubricated.
[0015] Further, the center of the upper two moving blocks lower end faces and the lower two moving blocks upper end faces is provided with a plurality of multi-section hydraulic cylinders, the eight multi-section hydraulic cylinders are divided into two groups, the output ends of the four multi-section hydraulic cylinders are provided with clamping devices, the clamping device comprises a fixed block, the fixed block is arranged on the upper end face of the moving block, the front and rear end faces of the fixed block are provided with grooves, the center of the rear inner wall of the front groove and the front inner wall of the rear groove is provided with a gas cylinder, the output ends of the two front gas cylinders and the two rear gas cylinders are provided with connecting plates;
[0016] Through the technical scheme, the multi-section hydraulic cylinders drive the clamping device to adjust up and down, and the connecting plates are driven to move by starting the gas cylinders, so that the first force clamping of the blade is satisfied, and the self-adaptive clamping according to the thickness of the blade is realized.
[0017] Further, the center of the end faces between the two connecting plates is arranged in a rectangular shape and provided with four electric telescopic rods, the output ends of the four front electric telescopic rods and the four rear electric telescopic rods are provided with clamping plates, and the center of the end faces between the two clamping plates is provided with buffer cotton.
[0018] Through the technical scheme, the electric telescopic rods drive the clamping plates to move, so that the position and clamping force of the clamping plates can be accurately adjusted, the second force clamping of the blade is satisfied, and double force clamping is realized, so that the reliability and stability of the blade hoisting are ensured, and the buffer cotton can absorb the impact and vibration in the clamping process, so that the blade surface is prevented from being clamped by the clamping plate or damaged, and the safety of the clamping process is improved.
[0019] Further, the center of the upper end face of the hoisting box is arranged in a rectangular shape and provided with four lifting rings.
[0020] Through the technical scheme, the hoisting device is started, the lifting force of the lifting hook lifts the whole hoisting box, and the hoisting process is completed.
[0021] The utility model has the advantages of:
[0022] 1. In this utility model, when the horizontal lifting fixture for wind turbine blades is used, the first rotary motor drives the first lead screw, connector, and second lead screw to rotate, enabling the moving frame to move horizontally. The second rotary motor drives the third lead screw to rotate, enabling the moving block to move back and forth. The multi-stage hydraulic cylinder enables the clamping device to move up and down, satisfying the needs of horizontal, moving, and vertical adjustment of the clamping device, and achieving multi-angle adjustment. It can be adjusted according to different blade sizes and types, thereby improving the flexibility and practicality of blade lifting work.
[0023] 2. In this utility model, lubricating oil is introduced into the oil storage tank through the grease nipple, and then the lubricating oil is carried into the connecting channel by the control of the micro pump, so as to meet the lubrication of the surface of the third lead screw. The lubricating oil drips from the surface of the third lead screw into the storage tank, and then meets the lubrication of the first lead screw and the second lead screw through the oil outlet hole. This reduces wear during movement, ensures the operational stability of the equipment, reduces the failure rate, ensures the smooth progress of the hoisting process, and realizes the automation of the lubrication process, reducing manual intervention.
[0024] 3. In this utility model, the connecting plate is moved by the starting cylinder, which satisfies the first force clamping of the blade and can adaptively clamp according to the blade thickness. Then, the clamping plate is moved by the electric telescopic rod, which can accurately adjust the position and clamping force of the clamping plate to satisfy the second force clamping of the blade. This achieves dual force clamping, thereby ensuring the reliability and stability of the blade hoisting. The buffer cotton can absorb the impact and vibration during the clamping process, prevent the blade surface from being pinched or damaged by the clamping plate, and improve the safety of the clamping process. Attached Figure Description
[0025] Figure 1 This is a perspective view of a horizontal hoisting fixture for wind turbine blades proposed in this utility model.
[0026] Figure 2 This is a three-dimensional sectional view of a horizontal hoisting fixture for wind turbine blades proposed in this utility model.
[0027] Figure 3 This is a perspective view of a horizontal hoisting fixture and clamping device for wind turbine blades proposed in this utility model.
[0028] Figure 4 This is a side sectional view of a horizontal hoisting fixture for wind turbine blades proposed in this utility model.
[0029] Figure 5 for Figure 2 Enlarged view of point A in the middle;
[0030] Figure 6 For Figure 4 Enlarged view at B.
[0031] Legend:
[0032] 1, hoisting box; 2, square groove; 3, moving adjusting device; 301, first rotary motor; 302, first screw rod; 303, connector; 304, second screw rod; 305, second rotary motor; 306, third screw rod; 4, moving frame; 5, moving block; 6, lubricating device; 601, oil storage tank; 602, oil injection nozzle; 603, micro pump; 604, connecting channel; 605, storage groove; 606, oil outlet hole; 7, multi-section hydraulic cylinder; 8, clamping device; 801, fixed block; 802, groove; 803, air cylinder; 804, connecting plate; 805, electric telescopic rod; 806, clamping plate; 807, buffer cotton; 9, lifting ring. DETAILED DESCRIPTION
[0033] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by the ordinary skilled in the art without creative labor fall within the scope of protection of the utility model.
[0034] With reference to Figures 1-6 The utility model provides an embodiment: a horizontal hoisting tool for wind turbine blade, including hoisting box 1 and two square grooves 2, two square grooves 2 are arranged respectively at both sides center place of hoisting box 1, and hoisting box 1 is equipped with moving adjusting device 3 at the center place of the upper and lower two inner walls.
[0035] The center of the upper end face of the two moving blocks 5 and the center of the lower end face of the two moving blocks 5 are provided with lubricating devices 6, the lubricating device 6 comprises an oil tank 601, the oil tank 601 is arranged at the center of the upper end face of the moving block 5, the center of the upper end face of the oil tank 601 is provided with an oil nozzle 602, and the center of the lower end face of the oil tank 601 is provided with a micro pump 603, the input end of the micro pump 603 penetrates through the lower end face of the oil tank 601 and reaches the inner wall of the oil tank 601, the output end of the micro pump 603 is provided with a connecting channel 604, the output end of the connecting channel 604 penetrates through the moving block 5 and reaches the inside of the moving block 5, the lubricating oil is introduced into the inside of the oil tank 601 through the oil nozzle 602, then the closing and starting of the micro pump 603 is controlled, so that the lubricating oil is brought into the connecting channel 604 and then is delivered to the inside of the moving block 5, thereby meeting the lubrication of the surface of the third lead screw 306, reducing the abrasion during movement, ensuring the operation stability of the equipment, reducing the failure rate, ensuring the smooth progress of the hoisting process, and realizing the automation of the lubrication process and reducing the manual intervention.
[0036] The center of the upper end face of the two moving blocks 5 and the center of the lower end face of the two moving blocks 5 are provided with lubricating devices 6, the lubricating device 6 comprises an oil tank 601, the oil tank 601 is arranged at the center of the upper end face of the moving block 5, the center of the upper end face of the oil tank 601 is provided with an oil nozzle 602, and the center of the lower end face of the oil tank 601 is provided with a micro pump 603, the input end of the micro pump 603 penetrates through the lower end face of the oil tank 601 and reaches the inner wall of the oil tank 601, the output end of the micro pump 603 is provided with a connecting channel 604, the output end of the connecting channel 604 penetrates through the moving block 5 and reaches the inside of the moving block 5, the lubricating oil is introduced into the inside of the oil tank 601 through the oil nozzle 602, then the closing and starting of the micro pump 603 is controlled, so that the lubricating oil is brought into the connecting channel 604 and then is delivered to the inside of the moving block 5, thereby meeting the lubrication of the surface of the third lead screw 306, reducing the abrasion during movement, ensuring the operation stability of the equipment, reducing the failure rate, ensuring the smooth progress of the hoisting process, and realizing the automation of the lubrication process and reducing the manual intervention.
[0037] The center of the upper end face of the two moving blocks 5 and the center of the lower end face of the two moving blocks 5 are provided with lubricating devices 6, the lubricating device 6 comprises an oil tank 601, the oil tank 601 is arranged at the center of the upper end face of the moving block 5, the center of the upper end face of the oil tank 601 is provided with an oil nozzle 602, and the center of the lower end face of the oil tank 601 is provided with a micro pump 603, the input end of the micro pump 603 penetrates through the lower end face of the oil tank 601 and reaches the inner wall of the oil tank 601, the output end of the micro pump 603 is provided with a connecting channel 604, the output end of the connecting channel 604 penetrates through the moving block 5 and reaches the inside of the moving block 5, the lubricating oil is introduced into the inside of the oil tank 601 through the oil nozzle 602, then the closing and starting of the micro pump 603 is controlled, so that the lubricating oil is brought into the connecting channel 604 and then is delivered to the inside of the moving block 5, thereby meeting the lubrication of the surface of the third lead screw 306, reducing the abrasion during movement, ensuring the operation stability of the equipment, reducing the failure rate, ensuring the smooth progress of the hoisting process, and realizing the automation of the lubrication process and reducing the manual intervention.
[0038] The four electric telescopic rods 805 and the four electric telescopic rods 805 at the rear are provided with clamping plates 806 at the output ends, and the center of the end face between the two clamping plates 806 is provided with buffer cotton 807. The clamping plate 806 is moved by the electric telescopic rod 805 to accurately adjust the position and clamping force of the clamping plate 806, meet the second clamping force of the blade, and realize double-acting force clamping, thereby ensuring the reliability and stability of the blade hoisting. The buffer cotton 807 can absorb the impact and vibration during clamping to prevent the blade surface from being damaged or damaged by the clamping plate 806, and improve the safety of the clamping process.
[0039] The lifting device is started, the lifting force of the lifting hook is used to lift the lifting box 1 as a whole, so that the lifting process is completed.
[0040] As shown in Figure 1 , 2 , 4, 6, the moving adjusting device 3 includes two horizontal moving assemblies and two front and rear moving assemblies. The two horizontal moving assemblies are arranged at the front and rear of the center of the lower end of the inner side wall of the lifting box 1. The upper center of the two horizontal moving assemblies is provided with a moving frame 4 on both sides. The two front and rear moving assemblies are arranged at the center of the inside of the two moving frames 4. The horizontal moving assembly includes a first rotary motor 301 arranged at the front end of the center of the lower end of the inner wall of the lifting box 1. The first rotary motor 301 is provided with a first lead screw 302 at one end. The first lead screw 302 is provided with a connector 303 at one end. The connector 303 is provided with a second lead screw 304 at one end. The second lead screw 304 is rotatably connected between the other inner side wall of the lifting box 1 through a bearing. The first lead screw 302 and the second lead screw 304 are respectively threadedly connected with the moving frame 4. The first rotary motor 301 drives the first lead screw 302 to rotate, and then drives the connector 303 and the second lead screw 304 to rotate. The first lead screw 302 and the second lead screw 304 are respectively threadedly connected with the moving frame 4, so that the moving frame 4 can be moved horizontally, and the size and type of the blade can be adjusted according to the target area.
[0041] The front and back moving assembly comprises a second rotary motor 305 arranged at the center of the inner wall of the rear of the moving frame 4, a third screw rod 306 arranged at the output end of the second rotary motor 305, one end of the third screw rod 306 being rotatably connected with the front inner wall of the moving frame 4 through a bearing, and a moving block 5 threadedly sleeved at the center of the outer side of the third screw rod 306. The second rotary motor 305 drives the third screw rod 306 to rotate, so that the moving block 5 is adjusted to move forward and backward, the clamping device 8 is adjusted to move horizontally and move, multi-angle adjustment is realized, the clamping device 8 can be adjusted according to different sizes and types of blades, and the flexibility and practicability of blade hoisting work are improved.
[0042] Working principle: when the horizontal hoisting tool for the wind turbine blade is used, the first rotary motor 301 drives the first screw rod 302 to rotate, the first screw rod 302 drives the connector 303 and the second screw rod 304 to rotate, the first screw rod 302 and the second screw rod 304 are respectively threadedly sleeved between the moving frame 4, so that the moving frame 4 is driven to move horizontally, the second rotary motor 305 drives the third screw rod 306 to rotate, so that the moving block 5 is adjusted to move forward and backward, the multi-section hydraulic cylinder 7 drives the clamping device 8 to adjust up and down, the clamping device 8 is adjusted to move horizontally, move and adjust up and down, multi-angle adjustment is realized, the clamping device 8 can be adjusted according to different sizes and types of blades, and the flexibility and practicability of blade hoisting work are improved.
[0043] Then the lubricating oil is introduced into the oil storage tank 601 through the oil injection nozzle 602, the micro pump 603 is controlled to be closed and started, the lubricating oil is brought into the connecting channel 604, and then the lubricating oil is delivered to the inside of the moving block 5, so that the surface of the third screw rod 306 is lubricated, the lubricating oil on the surface of the third screw rod 306 drops into the storage tank 605, and then the lubricating oil is delivered to the inside of the moving frame 4 through the oil outlet hole 606, so that the first screw rod 302 and the second screw rod 304 are lubricated, the abrasion during movement is reduced, the operation stability of the equipment is ensured, the failure rate is reduced, the hoisting process is ensured to be carried out smoothly, the lubrication process is realized to be automatic, and manual intervention is reduced.
[0044] Then the connecting plate 804 is driven to move by the starting cylinder 803, the first force clamping of the blade is realized, the self-adaptive clamping according to the thickness of the blade is realized, the clamping plate 806 is driven to move by the electric telescopic rod 805, the position and the clamping force of the clamping plate 806 can be accurately adjusted, the second force clamping of the blade is realized, the double force clamping is realized, the reliability and the stability of the blade hoisting are guaranteed, the impact and the vibration in the clamping process can be absorbed by the buffer cotton 807, the blade surface is prevented from being clamped and damaged by the clamping plate 806, and the safety of the clamping process is improved.
[0045] Finally, the lifting device is started, the lifting box 1 is lifted as a whole through the lifting force of the lifting hook, the blade is driven to move horizontally through the rotation of the first lead screw 302 and the second lead screw 304, the blade installation end is led out from the inside of the square groove 2, and the lifting process is completed through installation of the blade and the target position.
[0046] Finally, it should be noted that: the above only for the preferred embodiments of the utility model, and does not limit the utility model, although the utility model is described in detail with reference to the foregoing embodiments, for the person skilled in the art, it still can modify the technical scheme recorded in the foregoing each embodiment, or equivalent replacement to part of technical features, any modification, equivalent replacement, improvement etc. within the spirit and principles of the utility model, should be contained in the protection scope of the utility model.
Claims
1. A horizontal lifting fixture for wind turbine blades, comprising a lifting box (1) and two square slots (2), wherein the two square slots (2) are respectively disposed at the center of both sides of the lifting box (1), characterized in that: The hoisting box (1) is equipped with a movable adjustment device (3) at the center of both the upper and lower inner walls; The moving adjustment device (3) includes two horizontal moving components and two front and rear moving components. The two horizontal moving components are respectively located at the lower end of the center of the inner side wall of the hoisting box (1) near the front and rear. The two horizontal moving components are each provided with a moving frame (4) at the center of the upper end face near both sides. The two front and rear moving components are respectively located at the center of the two moving frames (4). The horizontal moving assembly includes a first rotary motor (301), which is located at the lower end of the center of an inner wall of the hoisting box (1) near the front end. A first lead screw (302) is provided at one end of the first rotary motor (301), a connector (303) is provided at one end of the first lead screw (302), and a second lead screw (304) is provided at one end of the connector (303). The second lead screw (304) is rotatably connected to the other inner wall of the hoisting box (1) through a bearing. The first lead screw (302) and the second lead screw (304) are threadedly connected to the moving frame (4).
2. The horizontal lifting fixture for wind turbine blades according to claim 1, characterized in that: The forward and backward moving assembly includes a second rotary motor (305), which is located at the center of the rear inner wall of the moving frame (4). A third lead screw (306) is provided at the output end of the second rotary motor (305). One end of the third lead screw (306) is rotatably connected to the front inner wall of the moving frame (4) through a bearing. A moving block (5) is threaded onto the center of the outer side of the third lead screw (306).
3. The horizontal lifting fixture for wind turbine blades according to claim 2, characterized in that: Lubrication devices (6) are provided at the center of the upper end face of the two lower movable blocks (5) and the lower end face of the two upper movable blocks (5). The lubrication device (6) includes an oil storage tank (601). The oil storage tank (601) is located at the center of the upper end face of the movable block (5). An oil injection nozzle (602) is provided at the center of the upper end face of the oil storage tank (601). A micro pump (603) is provided at the center of the lower end face of the oil storage tank (601). The input end of the micro pump (603) passes through the lower end face of the oil storage tank (601) and leads to the upper inner wall of the oil storage tank (601). A connecting channel (604) is provided at the output end of the micro pump (603). The output end of the connecting channel (604) passes through the movable block (5) and leads to the interior of the movable block (5).
4. The horizontal lifting fixture for wind turbine blades according to claim 1, characterized in that: Storage slots (605) are provided at the center of the upper inner wall of the two upper movable frames (4) and the lower inner wall of the two lower movable frames (4). Oil outlet holes (606) are provided at the front and rear of the center of the upper inner wall of the two upper storage slots (605) and the lower inner wall of the two lower storage slots (605). The eight oil outlet holes (606) pass through the inner walls of the four movable frames (4) and lead to the interior of the four movable frames (4).
5. The horizontal lifting fixture for wind turbine blades according to claim 2, characterized in that: Multi-segment hydraulic cylinders (7) are provided at the center of the lower end face of the two upper moving blocks (5) and the upper end face of the two lower moving blocks (5) on both sides. The eight multi-segment hydraulic cylinders (7) are divided into two groups. Clamping devices (8) are provided at the output ends of the four multi-segment hydraulic cylinders (7). The clamping device (8) includes a fixing block (801). The fixing block (801) is located on the upper end face of the moving block (5). The center of the front and rear end faces of the fixing block (801) is provided with a groove (802). The center of the rear inner wall of the groove (802) at the front and the front inner wall of the groove (802) at the rear is provided with a cylinder (803). The output ends of the two cylinders (803) at the front and the two cylinders (803) at the rear are provided with a connecting plate (804).
6. The horizontal lifting fixture for wind turbine blades according to claim 5, characterized in that: Four electric telescopic rods (805) are arranged in a rectangular pattern at the center of the end face between the two connecting plates (804). Clamping plates (806) are provided at the output ends of the four electric telescopic rods (805) at the front and the four electric telescopic rods (805) at the rear. Buffer cotton (807) is provided at the center of the end face between the two clamping plates (806).
7. The horizontal lifting fixture for wind turbine blades according to claim 1, characterized in that: The hoisting box (1) has four lifting rings (9) arranged in a rectangular pattern at the center of its upper end face.