A method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger

Abstract

This invention discloses a method for vertically arranging fishing net cutters on a trailing suction hopper dredger, comprising: before installation, applying a seawater corrosion-resistant coating to both the fishing net cutter and the anti-rope cover; arranging the fishing net cutter perpendicular to the anti-rope cover at the end of the tail shaft, with the cutting edge extending vertically so that the cutting direction is perpendicular to the direction of rotation of the fishing net and rope; fixing the fishing net cutter to the outer wall of the anti-rope cover with bolts, and connecting the anti-rope cover to the rear bearing flange of the tail tube with bolts, and reinforcing the connection points and flange mating areas with spot welding; controlling the distance between the anti-rope cover and the tail shaft flange cover to 5mm±1mm, and controlling the distance between two adjacent vertical cutters to 5mm±1mm. This invention achieves efficient cutting of fishing nets, ropes, and other debris by changing the installation angle of the fishing net cutter, optimizing the connection structure between the cutter and the anti-rope cover, and precisely controlling the fitting clearance, thus preventing them from entangled in the propeller and tail shaft from the source.

Description

Technical Field

[0001] This invention belongs to the technical field of trailing suction hopper dredger supporting equipment, specifically a method for vertically arranging the fishing net cutter of a trailing suction hopper dredger. Background Technology

[0002] Trailing suction hopper dredgers are core dredging equipment for infrastructure projects such as port and waterway upgrades and coastal reclamation. Their operating areas are mostly waters with a lot of fishing nets, ropes and other debris left in ports and waterways. During operation, the propeller at the end of the stern shaft is easily entangled by floating fishing nets and abandoned ropes, which can lead to equipment failures such as propeller jamming, stern shaft wear, and power system overload. This can not only interrupt dredging operations and cause economic losses, but may also cause safety hazards to the ship's navigation due to equipment damage.

[0003] To address the aforementioned issues, existing trailing suction hopper dredgers typically install a net cutter (rope cutter) at the rope guard at the end of the stern shaft, using a horizontal installation configuration. The clearance between the net cutter and the propeller hub is controlled between 2–8 mm. With this configuration, fishing nets smaller than 2–8 mm in diameter are intercepted by the net collector after entering the rope guard. The net cutter only cuts the debris when the amount of net entanglement exceeds the clearance value. However, this design has several drawbacks in actual operation: First, the horizontally arranged cutter has a low degree of matching between its cutting direction and the direction of the net or rope entanglement, resulting in poor cutting efficiency and a tendency to "not cut or break" debris, which remains entangled on the propeller or stern shaft. Second, the 2–8 mm clearance design causes small-diameter debris to accumulate in the collector, requiring frequent shutdowns for cleaning, thus affecting operational efficiency. Third, the connection structure between the horizontal cutter and the rope guard is not properly stressed, and long-term operation can lead to loosening and deformation, reducing the reliability of the protection.

[0004] Meanwhile, due to their compact hull space and flexible operating conditions, small and medium-sized handy-type trailing suction hopper dredgers place higher demands on the installation space, adaptability, and cutting efficiency of stern shaft protection equipment. The traditional horizontal net cutter arrangement is no longer suitable for their core requirements of "high efficiency, compactness, and continuous operation," and a better net cutter arrangement method is urgently needed to improve the debris cutting effect and stern shaft protection capability. Summary of the Invention

[0005] To address the aforementioned problems in the existing technology, this invention provides a method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger. By changing the installation angle of the fishing net cutter blades, optimizing the connection structure between the cutter blades and the anti-rope cover, and precisely controlling the fitting gap, efficient cutting of fishing nets, ropes, and other debris is achieved, preventing them from entangled in the propeller and tail shaft from the source.

[0006] The technical solution to achieve the above objectives is: A method for vertically arranging the cutting edge of a fishing net on a trailing suction hopper dredger includes: Step S1, anti-corrosion treatment: Before installing the fishing net cutter, apply an anti-seawater corrosion coating to the entire fishing net cutter and rope guard. Step S2, vertical installation of the fishing net cutter: The fishing net cutter is arranged perpendicular to the rope guard at the end of the tail shaft, and the cutting edge of the fishing net cutter extends in the vertical direction so that the cutting direction is perpendicular to the winding and rotating direction of the fishing net and rope. Step S3, Reinforcing the connection structure: The fishing net cutter is fixedly connected to the outer wall of the anti-rope cover by bolts. The anti-rope cover is connected to the rear bearing flange of the tail tube by bolts, and spot welding is performed to reinforce the connection and flange contact points. Step S4, gap control: The gap between the rope guard and the tail shaft flange is controlled at 5mm±1mm, and the gap between two adjacent vertical cutters is controlled at 5mm±1mm.

[0007] Preferably, in step S1, the surface of the fishing net cutter and the entire anti-rope cover are coated with epoxy paint + polishing anti-fouling paint, and the film thickness is controlled to be 500μm.

[0008] Preferably, in step S2, the fishing net cutter is made of 316L stainless steel and consists of a stationary blade and a moving blade. The stationary blade and the moving blade are arranged axially opposite to each other on the outer wall of the rope guard, and their blades interlock to form a shearing pair.

[0009] Preferably, in step S2, the stationary blade and the moving blade are arranged in pairs along the circumferential direction of the anti-rope cover, with a circumferential interval of 90° between each pair of stationary and moving blades. Each propeller is equipped with 4 pairs of shearing components, which are evenly distributed along the circumference of the anti-rope cover at 360°.

[0010] Preferably, in step S2, the stationary blade is arranged near the propeller hub, and the moving blade is arranged near the tailpipe rear bearing flange. During operation, the moving blade rotates synchronously with the tail shaft along with the anti-rope cover, forming a relative shearing motion with the stationary blade to cut off fishing nets, ropes, and debris that have entered the gap.

[0011] Preferably, in step S3, the spot welding process parameters are: weld leg 4mm, each weld segment 60mm, weld blank clearance 80mm, and wrap angle 50mm at each end; welding current 110~130A, welding speed 350~450mm / min.

[0012] Preferably, in step S4, the installation clearance is determined by both the propeller shaft diameter and the tail shaft speed. The axial clearance calculation formula is 0.03 to 0.04 × D, where D is the propeller shaft diameter. When the speed is ≥150 rpm, the axial clearance is increased by an additional 1 to 2 mm.

[0013] Preferably, in step S4, the propeller shaft speed is divided into three levels: low speed <150rpm, medium speed 150~300rpm, and high speed >300rpm. The higher the speed and the larger the shaft diameter, the larger the corresponding installation clearance.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention arranges the fishing net cutter and the anti-rope cover at the end of the tail shaft vertically. When the dredger is dredging in the port channel, the high-speed rotation of the propeller drives the tail shaft to rotate. Fishing nets, ropes, and other debris in the water gather towards the anti-rope cover under the action of water flow and centrifugal force. After contacting the vertically arranged cutter blade, they are quickly cut by the vertical cutting force. The cut debris is dispersed by the water flow and cannot form effective entanglement, ensuring the normal operation of the propeller and tail shaft. Even at low speeds, the rotation of the propeller can still bring debris into contact with the vertical cutter. The cutter can cut floating light debris in real time, preventing debris from accumulating at the anti-rope cover and eliminating the need for additional shutdown for cleaning. The vertically installed cutter blade is perpendicular to the entanglement direction of the fishing net and rope, resulting in more concentrated cutting force and achieving "cutting upon contact". Compared with traditional horizontal cutters, the thoroughness of debris cutting is improved, effectively preventing uncut debris from entangled in the propeller and tail shaft, solving the problem of machine damage from the source. The vertical arrangement of the fishing net cutters in this invention requires no additional space on the hull. The cutters are evenly distributed around the circumference of the anti-rope cover, resulting in a compact structure that perfectly suits the compact hull design of small and medium-sized portable trailing suction hopper dredgers. Furthermore, the modular configuration of the four cutters allows for flexible adjustment of the number and spacing of the cutters according to the propeller size of dredgers of different tonnages, offering wide adaptability. The cutters are made of 316L stainless steel, and both the anti-rope cover and the cutters undergo professional anti-seawater corrosion coating treatment, enabling long-term operation in high-salt, highly corrosive waters of ports and waterways. This reduces equipment corrosion and extends the cutter's service life to more than twice that of traditional cutters, reducing the frequency of equipment replacement. The optimized 5mm±1mm gap of this invention avoids the accumulation of small-diameter debris, eliminating the need for frequent shutdowns to clean the collector. At the same time, the spot welding reinforcement design of the cutter connection structure reduces the probability of equipment loosening and failure, lowers the rate of work interruption, and ensures the continuity of dredging operations. In this invention, the double connection of the anti-rope cover and the tailpipe rear bearing flange using bolts and spot welding, as well as the bolt and spot welding fixing of the cutter to the anti-rope cover, significantly improves the vibration resistance and deformation resistance of the overall connection structure, adapting to the severe vibration conditions during dredging operations. The cutter installation position remains unchanged, and the reliability of tail shaft protection is improved. When the fishing net cutter needs to be inspected or replaced, the spot welded parts and connecting bolts between the cutter and the anti-rope cover can be directly removed to complete the disassembly of the cutter. After the inspection is completed, it can be re-bolted and spot-welded for reinforcement. The disassembly and assembly process is simple, without the need to disassemble the anti-rope cover and tail shaft components, shortening the inspection time, improving equipment maintenance efficiency, and significantly reducing the labor and material costs of equipment maintenance, resulting in a significant reduction in long-term operating costs. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This invention relates to a method for vertically arranging the fishing net cutter of a trailing suction hopper dredger; Figure 2 This is a schematic diagram of the overall structure of the fishing net cutter vertically arranged on the trailing suction hopper dredger in this invention; Figure 3 yes Figure 2 Enlarged schematic diagram of the structure at point A in the middle; Figure 4 This is a schematic diagram of the anti-rope cover in this invention; Figure 5 This is a schematic diagram of the static blade in this invention; Figure 6 This is a schematic diagram of the moving blade in this invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] like Figure 1-6 As shown, a method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger includes: Step S1, anti-corrosion treatment: Before installing the fishing net cutter, the fishing net cutter and the anti-rope cover 2 are coated with an anti-seawater corrosion coating to ensure the overall corrosion resistance of the protective equipment and reduce the damage to the equipment caused by the marine environment.

[0018] In this embodiment, the surface of the fishing net cutter and the entire anti-rope cover 2 are coated with epoxy paint + polishing anti-fouling paint, and the film thickness is controlled to be 500μm.

[0019] Step S2, vertical installation of the fishing net cutter: The fishing net cutter is arranged perpendicularly to the anti-rope cover 2 at the end of the tail shaft. The cutting edge of the fishing net cutter extends vertically, so that the cutting direction is perpendicular to the direction of rotation of the fishing net and rope. Compared with the traditional horizontal cutter, the thoroughness of debris cutting is improved, effectively preventing uncut debris from getting tangled in the propeller and tail shaft, solving the problem of machine damage from the source. The vertical arrangement does not require additional space on the hull. The cutter is evenly distributed around the circumference of the anti-rope cover, with a compact structure that perfectly fits the compact hull space of small and medium-sized handy trailing suction hopper dredgers. At the same time, the modular configuration of the 4 cutters can flexibly adjust the number of cutters and the installation spacing according to the propeller size of dredgers of different tonnages, making it widely adaptable.

[0020] like Figure 3 , 5 As shown in Figure 6, the fishing net cutter is made of 316L stainless steel. The fishing net cutter consists of a stationary blade 11 and a moving blade 12. The stationary blade 11 and the moving blade 12 are arranged axially opposite to each other on the outer wall of the rope guard 2. The blades of the two blades interlock to form a shearing pair. The stationary blade 11 and the moving blade 12 are arranged in pairs along the circumference of the anti-rope cover. The circumferential interval between each pair of stationary and moving blades is 90°. Each propeller is equipped with 4 pairs of shearing components, which are evenly distributed along the circumference of the anti-rope cover in 360°. The stationary blade 11 is arranged near the propeller hub, and the moving blade 12 is arranged near the tailpipe rear bearing flange. During operation, the moving blade 12 rotates synchronously with the tail shaft along with the anti-rope cover 2, forming a relative shearing motion with the stationary blade 11 to cut off fishing nets, ropes and debris that enter the gap.

[0021] Step S3, Reinforcing the Connection Structure: The fishing net cutter is fixedly connected to the outer wall of the anti-rope cover 2 by bolts. The anti-rope cover 2 is bolted to the rear bearing flange of the stern tube, and spot welding is used to reinforce the connection and flange fit. The double connection of the anti-rope cover 2 and the rear bearing flange of the stern tube with bolts and spot welding, as well as the bolt and spot welding fixation of the cutter to the anti-rope cover 2, greatly improves the vibration resistance and deformation resistance of the overall connection structure, adapts to the severe vibration conditions during dredging operations, ensures no offset of the cutter installation position, and improves the reliability of stern shaft protection.

[0022] In this embodiment, the spot welding process parameters are as follows: weld leg 4mm, each weld segment 60mm, weld clearance 80mm, and wrap angle 50mm at each end; welding current 110-130A, welding speed 350-450mm / min.

[0023] Step S4, with gap control: the gap between the anti-rope cover 2 and the tail shaft flange cover is controlled at 5mm±1mm, and the gap between two adjacent vertical cutters is controlled at 5mm±1mm. This avoids the accumulation of small-diameter debris, eliminates the need for frequent shutdowns to clean the collector, and the spot welding reinforcement design of the cutter connection structure reduces the probability of equipment loosening and failure, reduces the interruption rate of operation, and ensures the continuity of dredging operations.

[0024] In this embodiment, the installation clearance is determined by both the propeller shaft diameter and the tail shaft speed. The axial clearance is calculated as 0.03 to 0.04 × D, where D is the propeller shaft diameter. When the speed is ≥150 rpm, the axial clearance is increased by an additional 1 to 2 mm.

[0025] In this embodiment, the propeller shaft speed is divided into three levels: low speed <150rpm, medium speed 150~300rpm, and high speed >300rpm. The higher the speed and the larger the shaft diameter, the larger the corresponding installation clearance.

[0026] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger, characterized in that, include: Step S1, anti-corrosion treatment: Before installing the fishing net cutter, the fishing net cutter and the anti-rope cover (2) are coated with an anti-seawater corrosion coating. Step S2, vertical installation of the fishing net cutter: The fishing net cutter is arranged vertically with the anti-rope cover (2) at the end of the tail shaft, and the cutting edge of the fishing net cutter extends in the vertical direction so that the cutting direction is perpendicular to the winding and rotating direction of the fishing net and rope. Step S3, Reinforcement of connection structure: The fishing net cutter is fixedly connected to the outer wall of the anti-rope cover (2) by bolts. The anti-rope cover (2) is bolted to the rear bearing flange of the tail pipe, and spot welding is performed at the connection and flange contact points for reinforcement. Step S4, gap control: the gap between the anti-rope cover (2) and the tail shaft flange cover is controlled at 5mm±1mm, and the gap between two adjacent vertical cutters is controlled at 5mm±1mm.

2. The method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 1, characterized in that, In step S1, the surface of the fishing net cutter and the entire rope guard (2) are coated with epoxy paint + polishing anti-fouling paint, and the film thickness is controlled to be 500μm.

3. The method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 1, characterized in that, In step S2, the fishing net cutter is made of 316L stainless steel. The fishing net cutter consists of a stationary blade (11) and a moving blade (12). The stationary blade (11) and the moving blade (12) are arranged axially opposite to each other on the outer wall of the rope cover (2). The blades of the two blades interlock to form a shearing pair.

4. The method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 3, characterized in that, In step S2, the stationary blade (11) and the moving blade (12) are arranged in pairs along the circumference of the rope guard. The circumferential interval between each pair of stationary and moving blades is 90°. Each propeller is equipped with 4 pairs of shearing components, which are evenly distributed along the circumference of the rope guard at 360°.

5. A method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 3, characterized in that, In step S2, the stationary blade (11) is arranged near the propeller hub, and the moving blade (12) is arranged near the tailpipe rear bearing flange. During operation, the moving blade (12) rotates synchronously with the tail shaft along with the anti-rope cover (2), forming a relative shearing motion with the stationary blade (11) to cut off the fishing nets, ropes and debris that enter the gap.

6. A method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 1, characterized in that, In step S3, the spot welding process parameters are: weld leg 4mm, each weld segment 60mm, weld blank clearance 80mm, and wrap angle 50mm at each end; welding current 110~130A, welding speed 350~450mm / min.

7. The method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 1, characterized in that, In step S4, the installation clearance is determined by both the propeller shaft diameter and the tail shaft speed. The formula for calculating the axial clearance is 0.03 to 0.04 × D, where D is the propeller shaft diameter. When the speed is ≥150 rpm, the axial clearance is increased by an additional 1 to 2 mm.

8. A method for vertically arranging the fishing net cutter blades of a trailing suction hopper dredger according to claim 1, characterized in that, In step S4, the propeller shaft speed is divided into three levels: low speed <150rpm, medium speed 150~300rpm, and high speed >300rpm. The higher the speed and the larger the shaft diameter, the larger the corresponding installation clearance.

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