A cutting device and cutting method for underwater pipelines

Abstract

The application discloses a cutting device and a cutting method special for underwater pipelines, which comprises nine water pipes and an underwater cutting machine. The underwater cutting machine comprises a motor, a cutting head and three nozzles. The three nozzles are arranged uniformly along the circumferential direction on the cutting head and have the same structure. The nine water pipes are composed of three groups of water pipes formed by one high-pressure high-speed water pipe, one low-pressure low-speed water pipe and one peripheral protection water pipe. One group of water pipes is connected with one nozzle. The incident pressure of fluid into the high-pressure high-speed water pipe and the low-pressure low-speed water pipe is controlled. The high-pressure high-speed water and the low-pressure low-speed abrasive water meet in front of the nozzle outlet to generate cavitation phenomenon. The low-pressure low-speed abrasive water and two water streams sprayed from the peripheral protection water nozzle meet in front of the nozzle outlet to further generate cavitation effect. The abrasive, the bubble groups on both sides and the water jointly act on the surface of the pipeline to be cut. The peripheral protection water extrudes the abrasive to the cutting area to enhance the cutting.

Description

Technical Field

[0001] This invention belongs to the field of mechanical cutting, and relates to underwater cutting technology, specifically to a special cutting device for underwater cutting of underwater pipelines using the shearing effect of cavitation water jets. Background Technology

[0002] To develop marine resources, underwater cutting operations are frequently required in marine engineering, such as repairing underwater pipelines, dismantling marine structures, and conducting seabed maintenance. Traditional cutting methods have limitations in underwater applications, such as the heat-affected zone caused by traditional thermal cutting and the poor applicability of mechanical cutting. Therefore, the demand for more advanced and efficient underwater cutting technologies is gradually increasing.

[0003] Waterjet cavitation technology is an advanced technique that utilizes the cavitation effect generated by high-speed water flow. The shock waves caused by bubble collapse enable cutting, cleaning, and surface treatment. It is a non-thermal cutting method that reduces the thermal impact on materials compared to high-temperature cutting methods, making it suitable for processing heat-sensitive materials. Compared to mechanical cutting methods, waterjet cavitation technology generates relatively low noise, reducing its impact on the working environment and operators. A high-speed water flow generated by a high-pressure water pump is channeled through a special nozzle to form a high-speed jet, providing sufficient kinetic energy for cutting and cleaning. Since the cutting process primarily relies on the water flow and the shock waves generated by bubble collapse, waterjet cavitation technology is applicable to various materials, including metals and concrete. When a high-speed water flow is sprayed onto the target surface, some of the water is rapidly depressurized, forming tiny bubbles—a process known as cavitation. These bubbles undergo pressure changes as the water flow moves. When the water flow stops or changes direction rapidly, the bubbles collapse. The shock waves generated during bubble collapse can produce extremely high pressure in a very short time. These high-pressure shock waves are used for cutting, cleaning, or surface treatment.

[0004] High-pressure abrasive jet underwater cutting technology introduces abrasive particles into waterjet cutting. Cutting is achieved by using high-speed water flow to carry the abrasive particles. Essentially, it is the accumulation of minute kinetic energy over time, increasing the kinetic energy of the water flow to cut objects. It generates less heat during operation, reducing the heat-affected zone and thus minimizing the risk of material deformation and deterioration. It can improve cutting efficiency, reduce heat impact, and is applicable to more materials, meeting the safety and environmental protection requirements of modern engineering.

[0005] The underwater cutting device disclosed in Chinese Patent Publication No. CN1730241A, entitled "Hydraulic Self-Spinning Controllable Abrasive Jet Cutting Device and Its Operation Method", includes an outer cylinder, a central shaft, a speed control mechanism, a high-pressure anti-sand mechanism, a cutting head, and an abrasive slurry. The speed control mechanism controls the rotation speed by increasing resistance through a special thickener filled between the inner cavity of the outer cylinder and the central shaft. However, the device has the following problems: 1. The abrasive jetting out of the high-pressure water will cause wear on the high-pressure nozzle; 2. The cutting range is limited and multi-angle cutting is not possible; 3. The abrasive loss is relatively large. The underwater cutting machine disclosed in Chinese Patent Publication No. CN117817567A, entitled "A Mobile Waterjet Cutting Machine for Underground Wells", includes a cutting machine body, a fixed ring cylinder, a waterjet spraying mechanism, an angle adjustment mechanism, a drive mechanism, and a base plate. It is equipped with moving wheels at the bottom corners to facilitate small-range adjustment and cutting at both ends. However, the device has the following problems: 1. It is impossible to determine whether the cutting is complete during waterjet cutting; 2. It is difficult to adjust the cutting range at multiple angles, and the range is relatively limited; 3. The cutting efficiency is low. Summary of the Invention

[0006] The purpose of this invention is to address the problems of low underwater cutting efficiency, easy wear of high-pressure nozzles, high abrasive loss, limited cutting range, and difficulty in multi-angle adjustment in the existing technology, and to provide a dedicated underwater pipe cutting device and method with high underwater cutting efficiency, large cutting range, and multi-angle adjustment capability.

[0007] To achieve the above objectives, the technical solution of the underwater pipe cutting device of the present invention is as follows: it includes nine water pipes and an underwater cutting machine. When the underwater cutting machine is working, it extends into the pipe to be cut. The nine water pipes are located outside the pipe to be cut and are connected to the underwater cutting machine via water pipes. The underwater cutting machine includes a motor, a cutting head, and three nozzles. The motor drives the cutting head to rotate above it. The cutting head has three nozzles with identical structures, evenly arranged circumferentially. The motor is fixed directly above a support frame, and a telescopic support frame that can freely extend and retract along the diameter of the pipe to be cut and does not rotate with the motor is fixedly connected below the support frame. The nine water pipes are three groups of water pipes: one high-pressure, high-speed water pipe, one low-pressure, low-speed water pipe, and one outer protective water pipe. The system comprises a set of water pipes connected to a nozzle; each nozzle has an annular high-pressure, high-speed water nozzle channel, a low-pressure, low-speed water nozzle channel, and an outer protective water nozzle channel, separated by two annular baffles from the inside out; the outlet of the high-pressure, high-speed water pipe in each set of water pipes corresponds to the inlet of the high-pressure, high-speed water nozzle channel in a nozzle, the outlet of the low-pressure, low-speed water pipe in each set of water pipes corresponds to the inlet of the low-pressure, low-speed water nozzle channel in a nozzle, and the outlet of the outer protective water pipe in each set of water pipes corresponds to the inlet of the outer protective water nozzle channel in a nozzle; the water pressure in the outer protective water pipe is between the water pressure in the high-pressure, high-speed water pipe and the water pressure in the low-pressure, low-speed water pipe; an abrasive mixing chamber is provided on the low-pressure, low-speed water pipe, and the abrasive is installed inside the abrasive mixing chamber.

[0008] Furthermore, a backflow detection device is installed above the outlet of each nozzle. The upper ends of the three backflow detection devices are fixedly connected to the circumferential edge of the cutting head and rotate with the cutting head. Each backflow detection device has an arc-shaped or L-shaped pipe that runs vertically through the nozzle, and each has a backflow detection pressure gauge inside that can detect the backflow water pressure.

[0009] The cutting technique employed by the underwater pipeline cutting device of this invention comprises the following steps:

[0010] A: Controlling the injection pressure of the fluid entering the high-pressure, high-speed water pipeline and the low-pressure, low-speed water pipeline, the high-pressure, high-speed water and the low-pressure, low-speed abrasive water meet in front of the nozzle outlet, generating cavitation; at the same time, the low-pressure, low-speed abrasive water and the two streams of water ejected from the outer protective water nozzle channel meet in front of the nozzle outlet, further generating cavitation effect; the abrasive and the bubble groups generated by the cavitation on both sides, together with the water, act on the surface of the pipe being cut, and the outer protective water concentrates the abrasive towards the cutting area to enhance the cutting;

[0011] B: When one of the nozzles has not finished cutting, the nozzle that has finished cutting stops working, while the nozzle that has not finished cutting continues step A until it is finished cutting. Then the motor rotates forward or backward by 1° or 2°, and steps A and B are repeated until all three nozzles have finished cutting.

[0012] Compared with the prior art, the present invention has the following outstanding advantages:

[0013] (1) The present invention reduces the consumption of abrasive particles by mixing abrasive particles in low-pressure, low-speed water, and reduces the wear of high-pressure nozzles caused by mixing abrasive particles in high-pressure, high-speed water nozzles.

[0014] (2) This invention utilizes the interaction between high-pressure high-speed water, low-pressure low-speed water in the nozzle, and the peripheral protective water with water pressure between the high-pressure high-speed water and the low-pressure low-speed water to generate a cavitation effect for underwater cutting. Under different pressures, the pressure of the peripheral protective water causes the abrasive to be squeezed towards the center. The bubble group generated by the collapse of the cavitation effect and the abrasive continuously collide with each other and, under the combined action of water, achieve the cutting of the object surface, thus enhancing the cutting effect.

[0015] (3) The present invention is equipped with three nozzles that work independently. The total working range of the three nozzles forms a ring. Each nozzle has a working range of less than 120° under the control of motor rotation. The cutting range can be adjusted at multiple angles. The three nozzles can cut at the same time, thereby achieving high-speed and high-efficiency ring cutting.

[0016] (4) This invention incorporates a backflow detection device in the cutting area of ​​the target material. Before the cutting operation, three nozzles respectively spray high-pressure, high-speed water, low-pressure, low-speed water, and peripheral protective water. At this time, the low-pressure, low-speed water pipe is temporarily free of abrasive. By detecting the spraying and sputtering pressure of the water jet, the optimal angle between the perpendicular bisector of the lower outlet of the backflow detection device and the nozzle axis is determined, thereby achieving optimal detection of the water jet cutting sputtering pressure. When the cutting fails to penetrate the target material, the water generated by the sputtering enters the backflow detection device, and the water flow pressure is monitored in real time to determine whether the cutting is complete. The angle between the perpendicular bisector of the lower outlet of the backflow detection device and the nozzle axis can be adjusted according to the cutting requirements of different materials and structures, as well as the high-pressure water pressure, to improve the accuracy of backflow monitoring.

[0017] (5) This invention sets up a system that, by adjusting the frequency converters in the high-pressure and low-pressure pipelines, can control the rotational speed of the water pumps in the high-pressure and low-pressure pipelines, thereby controlling the pressure of the fluids entering the high-pressure and low-pressure pipelines and achieving the goal of efficient cutting. Through the ingenious combination of high-pressure, high-speed water flow and low-pressure, low-speed abrasive water flow, the cutting speed and efficiency are improved by utilizing shearing action and cavitation effect, and the cutting accuracy is also greatly enhanced. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of a special underwater pipe cutting device according to the present invention;

[0019] Figure 2 yes Figure 1 Enlarged view of the underwater cutting machine structure;

[0020] Figure 3 yes Figure 2 A magnified three-dimensional schematic diagram of a nozzle.

[0021] Figure 4 yes Figure 3 Rear axle view;

[0022] Figure 5 yes Figure 2 A cross-sectional magnified view of one of the nozzles and its working status indication;

[0023] Figure 6 yes Figure 2 An enlarged status diagram of a nozzle and its corresponding backflow detection device;

[0024] Figure 7 yes Figure 6 Diagram illustrating the working status of the mid-flow detection device for detecting splash water pressure;

[0025] Figure 8 yes Figure 7 Diagram illustrating the working status of the reflux detection device at a large sputtering angle;

[0026] Figure 9 yes Figure 7 Diagram illustrating the operating status of the reflux detection device at a small sputtering angle;

[0027] Figure 10 yes Figure 1 A schematic diagram of the clamping mechanism of the underwater cutting machine.

[0028] Explanation of reference numerals in the attached drawings: 1. Primary filter; 2. Valve; 3. Secondary filter; 4. Low-pressure pump; 5. High-pressure pump; 6. Frequency converter; 7. Controller; 8. Pressure gauge; 9. Abrasive mixing chamber; 10. Agitator; 11. Underwater cutting machine; 12. Motor; 13. Bolt; 14. Fixed bracket; 15. Telescopic bracket; 16-1. First reflux detection device; 16-2. Second reflux detection device; 16-3. Third reflux detection device; 16-4. Rotating component; 17. Cutting head; 1 8. Nozzle; 18-1. First nozzle; 18-2. Second nozzle; 18-3. Third nozzle; 19. Rolling bearing; 20. Motor output shaft; 21-1. High-pressure high-speed water nozzle channel; 21-2. Low-pressure low-speed water nozzle channel; 21-3. External protective water nozzle channel; 21-4. Baffle; 22. Abrasive; 23. Bubble cluster; 100. Pipe to be cut; 101. First clamping arm; 102. Second clamping arm; 103. Telescopic rod; 104. First clamp; 105. Second clamp. Detailed Implementation

[0029] like Figure 1 As shown, the underwater pipe cutting device of the present invention includes nine water pipes and an underwater cutting machine 11. When the underwater cutting machine 11 is working, it extends into the pipe to be cut. The nine water pipes are located outside the pipe to be cut and are connected to the underwater cutting machine 11 inside the pipe through the water pipes.

[0030] The underwater cutting machine 11 includes a motor 12, a cutting head 17, and three nozzles 18. The motor 12 is located above the cutting head 17 and drives the cutting head 17 to rotate. The cutting head 17 is equipped with three nozzles 18, which are designated as the first nozzle 18-1, the second nozzle 18-2, and the third nozzle 18-3.

[0031] The nine water pipes consist of three high-pressure, high-speed water pipes (G), three low-pressure, low-speed water pipes (D), and three outer protection water pipes (W). Each group is composed of one high-pressure, high-speed water pipe (G), one low-pressure, low-speed water pipe (D), and one outer protection water pipe (W). These three groups correspond to three nozzles, with each group connecting to one nozzle. The three high-pressure, high-speed water pipes (G), the three low-pressure, low-speed water pipes (D), and the three outer protection water pipes (W) all have identical structures.

[0032] The inlets of nine water pipes are all connected to a primary filter 1, through which water is drawn directly from underground. The output of the primary filter 1 is connected to the inlets of six valves 2. Each group of water pipes has a low-pressure, low-speed water pipe D with a valve 2, the outlet of which is connected to a corresponding secondary filter 3. Each group of water pipes also has a high-pressure, high-speed water pipe G and an outer protective water pipe W sharing another valve 2, the outlet of which is connected to two secondary filters 3. Therefore, there are a total of nine secondary filters 3, one on each water pipe. The nine water pipes, through the two filtration processes of the primary filter 1 and secondary filters 3, remove impurities from the water, preventing clogging of the nozzles on the underwater cutter 11 and ensuring the normal operation of the high-pressure pump and pipelines. The valve 2 installed between the primary filter 1 and the secondary filter 3 controls the water intake.

[0033] The output of the secondary filter 3 in each low-pressure, low-speed water pipeline D is sequentially connected to a corresponding low-pressure pump 4, a corresponding pressure gauge 8, a corresponding abrasive mixing chamber 9, and a corresponding nozzle. The three pressure gauges 8 in the three low-pressure, low-speed water pipelines D are pressure gauges P1, P4, and P7, respectively. Each low-pressure pump 4 is connected to a corresponding frequency converter 6. The low-pressure pumps 4 and all pressure gauges 8 are connected to the controller 7. The low-pressure, low-speed water is supplied with low pressure by the low-pressure pumps 4 on their respective water pipelines, and the speed is adjusted by the frequency converter 6. The controller 7 controls the start and stop of the low-pressure pumps 4. The corresponding pressure gauges 8 are installed after the low-pressure pumps 4 to monitor the low pressure in real time and feed the data back to the controller 7. The abrasive mixing chamber 9 installed in the low-pressure, low-speed water pipeline D contains abrasive and a stirrer 10. Low-pressure, low-speed water flows into the abrasive mixing chamber 9 and is stirred by the rotation of the stirrer 10. After being fully mixed with the abrasive, it flows into the nozzle. By using low-pressure, low-speed water to mix abrasive particles, the consumption of abrasive particles can be reduced and the wear of the high-pressure nozzle caused by mixing abrasive particles in the high-pressure, high-speed water nozzle can be reduced.

[0034] The output of the secondary filter 3 in each high-pressure, high-speed water pipeline G and the outer protective water pipeline W is sequentially connected to a corresponding high-pressure pump 5, a corresponding pressure gauge 8, and a corresponding nozzle. Each high-pressure pump 5 is connected to a corresponding frequency converter 6. The six pressure gauges 8 in the three high-pressure, high-speed water pipelines G and the three outer protective water pipelines W are pressure gauges P2, P3, P5, P6, P8, and P9, respectively. The high-pressure pumps 5 and their corresponding pressure gauges 8 are all connected to the controller 7. High-pressure, high-speed water is supplied by the high-pressure pumps 5 on their respective pipelines, and the speed is adjusted by the corresponding frequency converters 6. The controller 7 controls the start and stop of the high-pressure pumps 5. The corresponding pressure gauges 8 are installed after the high-pressure pumps 5 to monitor the high-pressure, high-speed water pressure in real time and feed the data back to the controller 7.

[0035] The water pressure in the outer protective water pipe W is between the water pressure in the high-pressure high-speed water pipe G and the water pressure in the low-pressure low-speed water pipe D. The main function of the outer protective water when it enters the nozzle is to protect the target material, reduce the impact and damage to non-target areas, and increase the cutting effect by squeezing the abrasive towards the center through the water pressure being lower than the high-pressure high-speed water inside the nozzle.

[0036] Each water pipe controls the speed of the high-pressure pump 4 or the low-pressure pump 5 by adjusting its corresponding frequency converter 6, thereby controlling the injection pressure. By controlling the jet velocity and pressure in the water pipe, the stroke of the jet during the initial formation, development, shedding, and collapse stages of cavitation is controlled. The controller 7 adjusts the fluid injection pressure in real time according to different materials, structures, and sizes.

[0037] like Figure 1 and Figure 2 As shown, in the underwater cutting machine 11, the housing of the motor 12 is fixed directly above the bracket 14. A telescopic bracket 15 is installed below the bracket 14. The bracket 14 is fixedly connected to the telescopic bracket 15 above it with bolts 13. The telescopic bracket 15 is fitted over the output shaft 20 of the motor 12, and the two are connected by a rolling bearing 19. The rolling bearing 19 supports the output shaft 20 of the motor 12 and is supported on the inner end face of the telescopic bracket 15, ensuring that the telescopic bracket 15 does not rotate with the motor 12. When the underwater cutting machine 11 extends into the pipe being cut, the telescopic bracket 15 can freely extend and retract along the diameter of the pipe. The telescopic bracket 15 can be controlled by a common hydraulic mechanism, which is connected to the controller 7.

[0038] The lower end of the output shaft 20 of the motor 12 is coaxially fixedly connected to the upper center of the cutting head 17, and is embedded in the upper center of the cutting head 17, driving the cutting head 17 to rotate synchronously.

[0039] The lower section of the cutting head 17 is conical, and three nozzles 18 are fixedly connected to the outer surface of the cone. These are the first nozzle 18-1, the second nozzle 18-2, and the third nozzle 18-3. The three nozzles have identical structures and are evenly arranged along the circumference. Under the rotation control of the motor 12, the working range of each nozzle is 120°, meaning it can rotate a maximum of 120°. Therefore, the total working range of the three nozzles 18 covers the entire inner wall of the pipe in a circumference.

[0040] A backflow detection device is installed above the outlet of each nozzle 18, namely the first backflow detection device 16-1, the second backflow detection device 16-2, and the third backflow detection device 16-3. The upper ends of all three backflow detection devices are fixedly connected to the circumferential edge of the cutting head 17 and rotate with the cutting head 17. Each backflow detection device has an arc-shaped or L-shaped through-pipe structure, and each has a backflow detection pressure gauge installed inside, for a total of three backflow detection pressure gauges. All three backflow detection pressure gauges are connected to the controller 7. The lower outlet of each backflow detection device is located near the outlet of its corresponding nozzle; that is, there is a backflow detection device next to the outlet of each nozzle. Water from the nozzle outlet splashes into the backflow detection device, and the backflow detection pressure gauge inside detects the splash water pressure. The backflow detection pressure gauge monitors pressure changes in real time to determine whether the cutting is complete. When the backflow detection pressure gauge in the backflow detection device detects splash pressure, it indicates that the cutting is not yet complete; when the splash pressure disappears, it indicates that the cutting operation is completely complete.

[0041] like Figure 2 , Figure 3 and Figure 4 As shown, the three nozzles 18 have the same structure. The central axis of the three nozzles 18 is at a certain angle to the central axis of the cutting head 17 and is inclined relative to the inner wall of the pipe. Each nozzle 18 has three annular nozzle water channels from the inside to the outside. The three annular nozzle water channels are all connected vertically. The three annular nozzle water channels from the inside to the outside are high-pressure high-speed water nozzle channel 21-1, low-pressure low-speed water nozzle channel 21-2, and outer protection water nozzle channel 21-3. They are separated by two annular baffles 21-4 to form three independent pipe nozzle water channels, which are also three water channels with different functions. The three annular nozzle water channels are arranged coaxially. The high-pressure, high-speed water nozzle channel 21-1 is in the middle and has the smallest inner diameter. The low-pressure, low-speed water nozzle channel 21-2 has a larger inner diameter than the high-pressure, high-speed water nozzle channel 21-1 and is coaxially fitted on the outside of the high-pressure, high-speed water nozzle channel 21-1. The outer protective nozzle water channel 21-3 has a larger inner diameter than the low-pressure, low-speed water nozzle channel 21-2 and is fitted on the outside of the low-pressure, low-speed water nozzle channel 21-2. The outer wall of the outer protective nozzle channel 21-3 is also the outer wall of the nozzle 18.

[0042] Each of the three sets of water pipes is connected to the same nozzle. The outlet of the high-pressure, high-speed water pipe G in each set of water pipes is connected to the inlet of the high-pressure, high-speed water nozzle channel 21-1 in the center of the nozzle. The outlet of the low-pressure, low-speed water pipe D in each set of water pipes is connected to the inlet of the low-pressure, low-speed water nozzle channel 21-2 in the nozzle. The outlet of the outer protective water pipe W in each set of water pipes is connected to the inlet of the outer protective water nozzle channel 21-3 in the nozzle.

[0043] like Figure 5 The upper inner diameter of the high-pressure, high-speed water nozzle channel 21-1 of each nozzle 18 is larger than the lower inner diameter, and the outlet is a cone that gradually increases in size from top to bottom. The outlet of the low-pressure, low-speed water nozzle channel 21-2 is a straight channel, and the outlet of the outer protective water nozzle channel 21-3 is a cone that gradually decreases in size from top to bottom.

[0044] like Figure 1 and Figure 6 The frequency converter 6 in the high-pressure high-speed water pipeline G and the low-pressure low-speed water pipeline D is adjusted to control the speed of the low-pressure pump 4 and the high-pressure pump 5, thereby precisely controlling the injection pressure of the fluid entering the high-pressure high-speed water pipeline G and the low-pressure low-speed water pipeline D. When the high-pressure high-speed water and the low-pressure low-speed abrasive water carrying abrasive 22 are ejected from the high-pressure high-speed water nozzle channel 21-1 and the low-pressure low-speed water nozzle channel 21-2 in the nozzle 18, respectively, the two water streams meet in front of the outlet of the nozzle 18. Due to the speed and pressure difference between the high-pressure high-speed water stream and the low-pressure low-speed abrasive water stream, a violent shearing action will occur when the two water streams meet. The change in velocity gradient will cause the local pressure to drop rapidly, making the local pressure lower than the saturated vapor pressure of the environment, thereby generating cavitation in this area and producing a bubble group 23. When the bubble group 23 generated by the cavitation phenomenon breaks, it releases huge energy, which, together with the abrasive 22 carried by the low-speed jet, acts on the surface of the pipe 100 being cut, initially achieving the cutting effect. Simultaneously, high-pressure, high-speed protective water is ejected from nozzle 18, while low-pressure, low-speed abrasive water and water ejected from the outer protective nozzle water channel 21-3 meet again in front of nozzle 18, generating intense shearing action and further cavitation. The abrasive 22 carried by the low-speed jet, along with the bubble clusters 23 generated by cavitation on both sides and the water, acts on the surface of the pipe 100 being cut, achieving a cutting effect and improving cutting efficiency. Furthermore, the outer protective water not only protects the material of the pipe 100 being cut, reducing impact and damage to non-target areas, but also, because its water pressure is between the water pressure in the high-pressure, high-speed water nozzle channel 21-1 and the water pressure in the low-pressure, low-speed water nozzle channel 21-2, concentrates the abrasive 22 towards the cutting area, further enhancing the cutting effect. Under the cavitation effect, the abrasive 22 carried by the low-speed abrasive water is concentrated and pushed towards the surface of the pipe 100 being cut, working together with the energy released by the bursting bubbles to achieve more precise and efficient cutting.

[0045] like Figure 7 , Figure 8 and Figure 9The backflow detection pressure gauge P10 inside the backflow detection device corresponding to the side of the nozzle 18 outlet is connected to the controller 7. A rotating component 16-4 is provided in the middle section of the backflow detection device. The rotating component 16-4 is controlled to rotate by the controller 17, which drives the lower section of the backflow detection device to rotate, so as to adjust the angle between the lower section and the upper section of the backflow detection device in real time, and also adjust the angle between the lower section of the backflow detection device and the central axis of the nozzle 18.

[0046] Before the cutting operation, controller 7 simultaneously controls three nozzles 18 to spray high-pressure, high-speed water, low-pressure, low-speed water, and peripheral protective water. At this time, no abrasive 22 is added to the abrasive mixing chamber 9, and no abrasive 22 is temporarily present in the low-pressure, low-speed nozzle water channel 21-2 for water jet mixing. Rotating component 16-4 adjusts the angle between the central axis of the lower outlet of the return flow detection device and the central axis of the nozzle 18, detecting the water jet cutting sputtering pressure. This adjusts the angle β (sputtering angle) between the central axis of the lower outlet of the return flow detection device and the central axis of the nozzle 18 to the optimal angle. Figure 7 By adjusting the included angle β, different materials and cutting requirements can be accommodated: for softer materials, the high-pressure water flow pressure is relatively low, and the sputtering angle is large, requiring the included angle β1 to be increased to ensure that the sputtering pressure can be accurately detected, such as... Figure 8 For harder materials, a higher pressure water jet is required, resulting in a smaller sputtering angle. In this case, the included angle β2 needs to be reduced, such as... Figure 9 This allows for precise monitoring of sputtering pressure. By dynamically adjusting the angle β of the reflow detection device, the cutting process can be optimized for different materials and cutting conditions, improving cutting accuracy and efficiency.

[0047] The real-time monitoring function of the backflow detection pressure gauge P10 ensures the safety and effectiveness of the cutting operation. When the backflow detection pressure gauge P10 detects the disappearance of the splashing pressure, it indicates that the cutting is completely completed, thereby improving the intelligence and automation level of the entire cutting process. When the cutting operation has completely penetrated the target material, high-pressure water will spray out from the cutting point, and at this time, the backflow detection device cannot detect the water splashing pressure. However, if the cutting fails to completely penetrate the material of the pipe 100 being cut, the impact of the high-pressure water flow will cause splashing. Some water will splash into the backflow detection device, where the backflow detection pressure gauge P10 monitors the water splashing pressure in real time to determine whether the cutting is complete. When the backflow detection pressure gauge P10 detects splashing pressure, it indicates that the cutting is not yet complete; when the splashing pressure disappears, it indicates that the cutting operation is completely completed.

[0048] like Figure 10As shown, the underwater cutting machine 11 needs to be connected to a clamping mechanism during cutting. It must be clamped first, and the clamping mechanism holds the underwater cutting machine 11 in place. This clamping mechanism includes a telescopic rod 103 parallel to the pipe 100 being cut, two clamping arms, and two clamps: a first clamping arm 101 and a second clamping arm 102, a first clamp 104, and a second clamp 105. The first clamping arm 101 and the second clamping arm 102 are arranged parallel to the vertical axis of the pipe 100 being cut. One end is fixedly connected to two different sections of the telescopic rod 103. One end of the first clamping arm 101 is fixedly connected to the lower section of the telescopic rod 103, and one end of the second clamping arm 102 is fixedly connected to the upper section of the telescopic rod 103. The other ends of both the first clamping arm 101 and the second clamping arm 102 are used to clamp or release the outer edge of the pipe 100 being cut. Both the first clamping arm 101 and the second clamping arm 102 are electric clamping arms, connected to a controller 7, and their operation is controlled by the controller 7. When the underwater cutting machine cuts inside the pipe, the telescopic rod 103 is firmly fixed to the outer edge of the pipe 100 being cut by the first clamping arm 101 and the second clamping arm 102.

[0049] Telescopic rod 103 is an electric telescopic rod connected to controller 7. The upper and lower telescopic arms of telescopic rod 103 can extend and retract vertically. The upper end of telescopic rod 103 clamps the telescopic bracket 15 on the underwater cutting machine 11 via first clamp 104 and second clamp 105, fixing and clamping the non-telescopic part of the telescopic bracket 15. The clamped part does not affect the extension and retraction of the telescopic bracket 15. The two telescopic arms of telescopic rod 103 can extend and retract axially, thereby driving the underwater cutting machine 11 to move axially within the pipe. After the underwater cutting machine 11 enters the pipe, it first moves axially via the telescopic arms of telescopic rod 103. The first clamp 104 and second clamp 105 drive the underwater cutting machine 11 until it reaches the desired cutting position. At this point, the telescopic bracket 15 then extends and retracts radially, causing its outer edge to engage with the inner wall of the pipe, thereby fixing the entire underwater cutting machine 11.

[0050] During cutting, each nozzle 18 of the underwater cutting machine 11 operates within a 120-degree range under the rotational control of the motor 12. The total working range of the three nozzles 18 forms the entire ring. The area cut simultaneously by the three nozzles 18 covers 360 degrees, ensuring that the high-pressure water flow can evenly cover the entire inner wall of the pipe, thereby achieving a ring-shaped cut of the pipe.

[0051] like Figure 1-10When starting work, controller 7 controls the first clamping arm 101 to clamp and fix it in place, while releasing the second clamping arm 102. Then, a section of the telescopic arm of the telescopic rod 103 extends and retracts freely while the first clamping arm 101 is fixed, moving the underwater cutter 11 to a new position. After moving to the new position, the second clamping arm 102 is fixed again. At this time, the first clamping arm 101 can be released, and the other section of the telescopic arm of the telescopic rod 103 can be extended and retracted to adjust to a new position, and then fixed again. The telescopic rod 103, through the first clamp 104 and the second clamp 105, extends the underwater cutter 11 into the pipe to be cut at the desired location, and through the telescopic bracket 15, it extends and retracts to clamp the inner wall of the pipe 100 to be cut, fixing it at the desired cutting position. After the cutting position is fixed, controller 7 controls the three nozzles 18 to start working. Before cutting, controller 7 controls three nozzles 18 to eject high-pressure, high-speed water, low-pressure, low-speed water, and peripheral protective water. At this time, no abrasive is added to the low-pressure, low-speed water pipe for mixing, and the water jet is ejected through the splash direction of the water jet out of the cutting pipe. The angle between the central axis of the lower outlet of the return flow detection device and the axis of the nozzle 18 is adjusted so that the pressure value of the water jet cutting splash can be detected. At this time, the angle between the central axis of the lower outlet of the return flow detection device and the axis of the nozzle 18 is fixed, and abrasive 22 is added to the abrasive mixing chamber 9, so that the abrasive 22 enters the low-pressure, low-speed water pipe D for water jet cutting.

[0052] When the backflow detection device detects that one of the nozzles 18 has not completed cutting, such as nozzle 18-1 not completing cutting while nozzles 18-2 and 18-3 have completed cutting, the nozzle 18 that has completed cutting stops working. That is, the controller 7 controls the valve 2 of a set of high-pressure high-speed water, low-pressure low-speed water and external protective water leading to nozzles 18-2 and 18-3 to close, thereby stopping nozzles 18-2 and 18-3 from working, while nozzle 18-1 that has not completed cutting continues to cut until cutting is completed.

[0053] When the backflow detection device detects that two nozzles 18 have not completed cutting, such as nozzles 18-1 and 18-2, but nozzle 18-3 has completed cutting, the controller 7 controls the valve 2 of a set of high-pressure high-speed water, low-pressure low-speed water and external protective water leading to nozzle 18-3 to close, thereby stopping the nozzle 18-3 that has completed cutting, while the nozzles 18-1 and 18-2 that have not completed cutting continue to cut until the cutting is completed.

[0054] When all three nozzles 18 have completed their cuts, and the backflow detection device does not detect any pressure value of the splashed water flow, it indicates that the nozzles 18 have completed the cuts at the three corresponding cutting points on the pipe. At this point, the controller 7 controls the motor 12 to rotate forward or backward by 1° or 2°, causing the three nozzles 18 to rotate to a new position to cut three new points. The cutting operation is then repeated. This process is repeated until each nozzle 18 rotates within 120° via the motor 12, meaning the working range of the nozzle 18 is controlled within 120°. When all three nozzles 18 have completed their cuts simultaneously, the combined working area covers 360 degrees, thus achieving a circular cut of the pipe 100 being cut.

[0055] When the annular cut of the pipe 100 is completed, the underwater cutting machine 11 needs to be moved to cut the next section. At this time, the new cutting position is adjusted by the cooperation of the first clamping arm 101 and the second clamping arm 102. The specific steps are as follows: When the cutting is completed, the controller 7 controls the first clamping arm 101 to remain stationary, the second clamping arm 102 releases the pipe 100 being cut, and then the position is adjusted by the extension and retraction function of the telescopic rod 103. One telescopic arm of the telescopic rod 103 can freely extend and retract while the first clamping arm 101 is fixed, driving the underwater cutter 11 to move axially to a new position inside the pipe 100 to be cut. After moving to the new position, the second clamping arm 102 fixes the pipe 100 to be cut. At this time, the first clamping arm 101 can be released, and the first clamping arm 101 can be adjusted to a new position by the telescopic function of the telescopic rod 103. Then, the first clamping arm 101 is fixed again. By releasing and clamping the two clamping arms back and forth, that is, by alternately fixing and moving the first clamping arm 101 and the second clamping arm 102, the position adjustment of the underwater cutter 11 is achieved. The telescopic rod 103 extends the underwater cutter 11 into the pipe 100 to be cut at the required cutting position through clamp one 104 and clamp two 105, and locks the underwater cutter 11 at the required cutting position by telescopic bracket 15. Through the above operations, the underwater cutting machine 11 can move segment by segment along the pipe 100 to be cut and perform continuous circular cutting, ensuring that the entire cutting process of the pipe 100 is efficient and continuous. After each position adjustment, precise clamping and telescopic movements ensure the stability and accuracy of the cutting process, thereby improving cutting efficiency and quality.

Claims

1. A special cutting device for underwater pipes, characterized in that: It includes nine water pipes and an underwater cutting machine (11). When the underwater cutting machine (11) is working, it extends into the pipe being cut. The nine water pipes are located outside the pipe being cut and are connected to the underwater cutting machine (11) through water pipes. The underwater cutting machine (11) includes a motor (12), a cutting head (17) and three nozzles (18). The motor (12) drives the cutting head (17) to rotate above the cutting head (17). The cutting head (17) is provided with three nozzles (18) with identical structures and evenly arranged in the circumferential direction. The motor (12) is fixed directly above the bracket (14). The lower part of the bracket (14) is fixedly connected to a telescopic bracket (15) that can freely extend and retract along the diameter of the pipe being cut and does not rotate with the motor (12). The nine water pipes are composed of three sets of water pipes: a high-pressure high-speed water pipe (G), a low-pressure low-speed water pipe (D), and an outer protection water pipe (W). Each set of water pipes is connected to a nozzle (18). Each nozzle (18) has an annular high-pressure high-speed water nozzle channel (21-1), a low-pressure low-speed water nozzle channel (21-2), and an outer protection water nozzle channel (21-3) that are separated from the inside out by two annular baffles (21-4). The outlet of the high-pressure high-speed water pipe (G) in each group of water pipes corresponds to the inlet of the high-pressure high-speed water nozzle channel (21-1) in a nozzle. The outlet of the low-pressure low-speed water pipe (D) in each group of water pipes corresponds to the inlet of the low-pressure low-speed water nozzle channel (21-2) in a nozzle. The outlet of the peripheral protection water pipe (W) in each group of water pipes corresponds to the inlet of the peripheral protection water nozzle channel (21-3) in a nozzle. The water pressure in the peripheral protection water pipe (W) is between the water pressure in the high-pressure high-speed water pipe (G) and the water pressure in the low-pressure low-speed water pipe (D). An abrasive mixing chamber (9) is provided on the low-pressure low-speed water pipe (D), and the abrasive mixing chamber (9) is filled with abrasive. The inner diameter of the low-pressure, low-speed water nozzle channel (21-2) is larger than that of the high-pressure, high-speed water nozzle channel (21-1), the inner diameter of the outer protective nozzle water channel (21-3) is larger than that of the low-pressure, low-speed water nozzle channel (21-2), and the outer wall of the outer protective water nozzle channel (21-3) is the outer wall of the nozzle (18). The upper inner diameter of the high-pressure high-speed water nozzle channel (21-1) of each nozzle (18) is larger than the lower inner diameter, and the outlet is a cone that gradually increases from top to bottom. The outlet of the low-pressure low-speed water nozzle channel (21-2) is a straight channel, and the outlet of the outer protective water nozzle channel (21-3) is a cone that gradually decreases from top to bottom.

2. The underwater pipeline cutting device according to claim 1, characterized in that: A backflow detection device is installed above the outlet of each nozzle (18). The upper ends of the three backflow detection devices are fixedly connected to the circumferential edge of the cutting head (17) and rotate with the cutting head (17). Each backflow detection device is an arc-shaped or L-shaped pipe that runs vertically through the pipe. Each device is equipped with a backflow detection pressure gauge that can detect the splash water pressure.

3. The underwater pipeline cutting device according to claim 2, characterized in that: The middle section of the reflux detection device is equipped with a rotating component (16-4) that drives the lower section to rotate, adjusting the angle between the lower section of the reflux detection device and the central axis of the nozzle (18).

4. A special underwater pipe cutting device according to any one of claims 1-3, characterized in that: Each low-pressure, low-speed water pipeline (D) includes a low-pressure pump (4), a corresponding pressure gauge (8), and a corresponding abrasive mixing chamber (9) connected in sequence. Each high-pressure, high-speed water pipeline (G) and the outer protective water pipeline (W) includes a high-pressure pump (5) and a corresponding pressure gauge connected in sequence. Each low-pressure pump (4) and high-pressure pump (5) has its speed adjusted by a frequency converter (6).

5. A cutting method based on the underwater pipeline cutting device according to any one of claims 1-3, characterized by comprising the following steps: A: Control the injection pressure of the fluid entering the high-pressure high-speed water pipe (G) and the low-pressure low-speed water pipe (D). The high-pressure high-speed water and the low-pressure low-speed abrasive water meet in front of the nozzle (18) and generate cavitation. At the same time, the low-pressure low-speed abrasive water and the two streams of water sprayed from the outer protective water nozzle channel (21-3) meet in front of the nozzle (18) and further generate cavitation effect. The abrasive and the bubble groups generated by the cavitation on both sides and the water work together on the surface of the pipe being cut. The outer protective water concentrates the abrasive (22) and squeezes it towards the cutting area to enhance the cutting. B: When one of the nozzles (18) has not finished cutting, the nozzle (18) that has finished cutting stops working, while the nozzle that has not finished cutting continues step A until it is finished cutting; then the motor (12) rotates forward or backward by 1° or 2°, and steps A and B are repeated until all three nozzles (18) have finished cutting.

6. The cutting method according to claim 5, characterized in that: Each nozzle (18) is controlled by a motor (12) to rotate within 120°.

7. The cutting method according to claim 5, characterized in that: The underwater cutting machine (11) is connected to the clamping mechanism. The clamping mechanism includes a telescopic rod (103) parallel to the pipe to be cut, as well as two clamping arms and two clamps. The two clamping arms are arranged in parallel, with one end fixedly connected to two different telescopic arms of the telescopic rod (103), and the other end can clamp or release the pipe to be cut. The upper end of the telescopic rod (103) clamps the non-telescopic part of the telescopic bracket (15) through the two clamps. When the cutting is completed, the first clamping arm is fixed and the second clamping arm is released. The underwater cutting machine (11) is moved to a new position by the extension and retraction of the telescopic rod (103). The first clamping arm is then released. The first clamping arm is adjusted to a new position by the extension and retraction of the telescopic rod (103) and then the first clamping arm is fixed again.

8. The cutting method according to claim 5, characterized in that: The sputtering pressure at the nozzle (18) outlet is monitored in real time by a backflow detection pressure gauge. When the backflow detection pressure gauge detects that the sputtering pressure has disappeared, it indicates that the cutting has been completed; when the sputtering pressure is detected, it indicates that the cutting has not been completed.

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