Low-speed self-rotating milling jet flow spray head tool

Abstract

The utility model relates to a low-speed self-rotating milling jet flow spray head tool which comprises an upper connector, a screw stator, a screw rotor, a flexible shaft, an anti-falling adjusting cap, a water cap, a spray head rotating shaft, a rotating shaft shell, an upper static block, a lower static block, a string bearing and various dynamic and static sealing rings. A low-speed self-rotating milling jet flow spray head tool is a downhole operation tool special for oil pipe sand removal, plug removal and oil pipe dredging, a chemical plug removal mode is often adopted in early-stage plug removal operation, but the yield and injection increasing effect is unstable due to non-uniformity of chemical agent injection, and the environment is polluted. And meanwhile, fixed hydraulic jet unblocking is not obvious in effect, short in effective period after construction and not easy to be matched with an acidified well for use, so that a low-speed self-rotating milling jet flow spray head tool capable of meeting the unblocking requirement in the acid environment is specially developed according to the problems in early-stage unblocking operation.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole tools for oil and gas drilling engineering, and relates to a novel rotary milling jet nozzle tool with low and adjustable speed, which is mainly used for sand flushing, descaling, cleaning and milling of oil wells. Background Art

[0002] During oil extraction, deposits and scale often accumulate inside oil pipes. These deposits reduce the efficiency of the fluid flow path within the pipes and can potentially lead to reduced oil and gas well production. Existing pipe cleaning equipment often suffers from low cleaning efficiency and rapid wear. Traditional nozzles, due to excessive rotation speed or improper design during high-pressure cleaning, can cause uneven wear and even damage the internal structure of the pipe. Therefore, there is an urgent need for a new nozzle that can efficiently and evenly remove deposits from the pipes while also offering a long service life.

[0003] Although the jet nozzle tools commonly used at this stage can blast sand and grind the inner wall of the casing to a certain extent, there are still some problems. For example, when the fluid displacement is too high, the rotation speed of the jet nozzle tools is very fast, and the liquid ejected is in mist, which cannot achieve the effect of jet flushing, and the vibration and impact are large, which reduces the stability and safety of the entire tool string; when the fluid displacement is too low, the jet nozzle tools are prone to not rotating and there is no rotating jet effect; in addition, some traditional construction operations use a tool combination of a screw motor and a fixed nozzle, which leads to the problem of increased tool string length. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a low-speed self-rotating milling jet nozzle tool for continuous oil pipes. The invention has a speed-controllable low-speed rotation function and combines the dual effects of milling and jetting to improve the cleaning efficiency of the inner wall of the oil pipe and the service life of the equipment.

[0005] In order to solve the above problems, the present invention adopts the following technical solutions:

[0006] A low-speed self-rotating milling jet nozzle tool comprises an upper joint, a screw stator connected to the upper joint by a thread, the screw rotor and the screw stator are matched by a spiral, the flexible shaft is in the hollow inner cavity of the screw rotor and is threadedly connected at the upper end, the female buckle at the upper end of the flexible shaft is connected to the male buckle of the anti-drop adjustment cap, the male buckle at the lower end of the flexible shaft is threadedly connected to the female buckle of the water cap, the upper static block and the outer cylindrical surface of the water cap are clearance-matched and a rotating dynamic sealing ring is provided in the middle, the male buckle at the upper end of the nozzle shaft is threadedly connected to the female buckle at the lower part of the water cap, the lower moving block is threadedly connected to the nozzle shaft, a mechanical sealing ring is provided between the lower static block and the lower moving block, a series bearing group is provided between the lower moving block and the water cap, the shaft housing is threadedly connected to the lower part of the screw stator, two oil filling holes are provided on the shaft housing, and the nozzle is connected to the nozzle shaft by a thread.

[0007] The screw rotor features a multi-threaded design, with an exterior surface chrome-plated or coated with carbide, adapting to various operating environments. The rotor is hollow. While the traditional design uses a threaded connection between the upper end of the flexible shaft and the lower end of the screw rotor, the new design connects the upper end of the flexible shaft to an internal female threaded connection at the upper end of the screw rotor. This significantly reduces the tool's overall length while ensuring flexibility. The hollow structure of the screw rotor significantly reduces the rotor's weight, thereby reducing the overall weight of the tool. This reduced overall weight reduces the burden on the support structure and improves installation and operational flexibility. The cross-sectional area formed by the screw rotor and the stator's inner cavity serves as the primary fluid flow channel, while the rotor's inner cavity serves as the secondary fluid flow channel, achieving a certain degree of fluid diversion. For a given flow rate through the primary channel, a higher thread count results in a lower speed. Therefore, adjusting the thread count ratio of the screw rotor to the stator is crucial for speed control. Ratios of 7:8, 9:10, 11:12, and above are all possible.

[0008] The anti-drop adjustment cap combines a drop-proof structure with a flow-through adjustment area. The drop-proof structure prevents the screw from loosening or falling during operation due to vibration, load fluctuations, or other factors. This physically prevents the screw from falling out due to vibration or impact, thereby reducing the risk of mechanical failure and potential safety hazards. This improves the overall reliability and lifespan of the tool string and effectively reduces the repair and replacement costs associated with screw loosening or falling, thereby lowering overall operating costs. The flex shaft has a flow hole. Adjusting the diameter of the hole in the anti-drop adjustment cap adjusts the flow ratio of the second flow channel, thereby adjusting the rotor speed. When the flow hole diameter increases, the flow ratio increases, meaning more fluid flows through the flex shaft flow hole, reducing fluid entering the stator and rotor space, and reducing the stator and rotor speed. When the flow hole diameter decreases, the flow ratio decreases, meaning more fluid flows through the stator and rotor space, driving the stator and rotor rotation and increasing the stator and rotor speed. In summary, the anti-drop adjustment cap not only prevents dropout but also allows for speed adjustment by adjusting the flow hole diameter, enabling low-speed operation. The adjusting function of the anti-drop adjusting cap is to adjust the fluid ratio of the two channels, namely the hollow cavity in the screw rotor and the gap between the screw stator and the screw rotor, thereby directly affecting the speed of the screw rotor and indirectly controlling the speed of the tool. Therefore, the anti-drop adjusting cap is an important structural basis for adjusting the tool speed of this tool.

[0009] The rotary dynamic seal, also known as the rotary step seal, consists of a rotating part and a stationary part. The two sealing surfaces slide relative to each other, creating a seal through precise mechanical contact. This effectively prevents fluid leakage and ensures cavity containment. It can withstand high speeds, pressures, and temperatures, and exhibits strong wear resistance. Replacing the original O-ring with a rotary dynamic seal improves sealing performance, preventing fluid from entering the string bearing and directing all fluid to the nozzle shaft. The use of a rotary dynamic seal compensates for the flow and pressure relief limitations of an open seal, allowing all fluid and impact forces to escape from the nozzle, resulting in a more powerful impact at the front of the nozzle.

[0010] The metal part of the screw stator is made of alloy steel, which makes the tool have higher strength, and the rubber part is made of high-quality imported high-temperature resistant hard rubber, which can adapt to harsh working environments and increase the service life of the tool.

[0011] The water cap features a wear-resistant alloy outer surface and a bypass hole. All fluid above the tool flows through the bypass hole into the nozzle shaft. The water cap is connected to the flexure at the top and the nozzle shaft at the bottom. The flexure drives the water cap, which in turn drives the nozzle shaft. The upper static block, abutting the outer surface of the water cap, does not rotate. This means the water cap rotates without the upper static block rotating. Because the abutting surface requires wear resistance, as ordinary alloy steel does not, wear-resistant carbide is used. This material can withstand greater radial forces and wear, extending the service life of the component and, ultimately, the entire tool.

[0012] A tandem bearing consists of multiple bearings arranged in series to form an integrated structure. They are used to carry and support various rotating shafts, improving the efficiency and lifespan of machinery. The upper part of a tool exerts axial forces on the lower part. Tandem bearings, with more balls than standard bearings, disperse the load and withstand greater shocks and loads. While maintaining the same axial force, the more bearings there are, the less axial force each ball bears, extending the lifespan of the balls and, consequently, the tandem bearing.

[0013] The lower stationary block is connected to the shaft housing and is stationary, while the lower moving block is connected to the nozzle shaft and rotates with it, maintaining its motion. This requires strong wear resistance, and is made of cemented carbide, which offers exceptional hardness and can withstand severe wear and greater radial forces, extending the life of the components and, consequently, the entire tool.

[0014] The mechanical seal, also known as the PanSeal seal, features a U-shaped sealing body with a spring clip inside the lip, providing excellent elasticity and resilience, ensuring sealing performance is unaffected by insufficient lubrication during startup. Several grooves are designed at the base of the U-shaped ring to relieve pressure at the base, preventing high pressure and movement or rotation of the seal within the groove. The chamfered inner diameter of the base protects the seal from extrusion damage. The PanSeal seal is dimensionally stable and offers far superior chemical and heat resistance than conventional rubber seals. It also eliminates the risk of volume expansion or contraction that can degrade sealing performance. When subjected to pressure, the material deforms to fill the gap between the sealing surfaces. Even at very low speeds, it operates very smoothly, with an extremely low coefficient of friction and no stick-slip effect. When pressure is released, the seal body quickly returns to its original shape, maintaining a tight seal. This allows the PanSeal seal to adapt to sealing surfaces of varying shapes and sizes, ensuring efficient sealing. An internal spring mechanism provides continuous preload. The spring's preload allows the seal body to fit tightly against the sealing surface, forming an effective sealing barrier. At the same time, the spring's energy storage function automatically compensates for changes in the sealing gap caused by wear, vibration, and other factors during operation, maintaining the stability of the sealing performance. The spring's shape concentrates the load on the leading edge of the sealing lip, giving the seal a reliable wiping effect. "U"-shaped springs have a medium load and deformation range, providing a larger compensation range and greater tolerance for shaft and bore runout and eccentricity. Other types of seals use interference during assembly to generate a preload, a force that is difficult to control. If the preload is weak or absent, achieving zero or micro-seal is difficult. However, due to the spring's clamping action, the lip of the universal seal always has an elastic force applied to it. Therefore, when the fluid is under no pressure or minimal pressure, the sealing lip still maintains a reliable sealing effect.

[0015] The nozzle shaft integrates the traditional milling head with the drive shaft. This one-piece design eliminates connection failures and instability, and reduces the risk of loosening or damage due to vibration or torque fluctuations. The one-piece structure is more robust and stable when subjected to pressure and torque, thereby improving tool efficiency and lifespan. This one-piece design typically reduces the number of parts, simplifies the manufacturing process and installation steps, and lowers production and maintenance costs. The one-piece structure transmits power more efficiently, reduces energy loss, and achieves higher efficiency. The one-piece structure is designed to better disperse stress, thereby improving fatigue resistance and extending tool life. The higher reliability and lower failure rate of the one-piece design reduce maintenance and replacement costs. The nozzle shaft has nozzle holes at the bottom, allowing the nozzle size and quantity to be adjusted according to actual conditions or needs. The nozzle holes can be arranged eccentrically and circumferentially. By arranging the nozzle hole axis out of alignment with the nozzle axis (i.e., an eccentric nozzle hole appears offset from the nozzle shaft axis when viewed from above or below), (the nozzle is fixed within the nozzle hole with its axis aligned with the nozzle hole axis), an eccentric distribution generates a velocity component along the nozzle's circumference. Based on the law of conservation of momentum and Newton's third law, the fluid ejected from the eccentric nozzle hole generates a circumferential thrust that propels the nozzle around its axis. This eccentricity creates torque, the tool's rotational driving force (torque). The eccentric nozzle hole design provides additional torque, in addition to the screw's torque, increasing the rotational torque of the nozzle shaft and providing a more reliable rotational force. Carbide teeth are welded to the top of the nozzle shaft, leveraging their high wear resistance, cutting efficiency, and hardness to improve drilling and grinding efficiency, enabling simultaneous milling and milling during jet cleaning.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] 1) The low-speed self-rotating milling jet nozzle tool offers a wider range of advantages over the traditional screw motor and mill shoe connection. The fluid flow ratio can be adjusted to achieve a lower rotational speed, making the tool more controllable. The tool length is greatly shortened while ensuring better functionality, saving space and costs for manufacturing, storage, and transportation. The stator and rotor in the tool serve as the power output, significantly improving rotational stability, making the speed more stable and controllable, reducing torque transmission losses, and achieving more complete torque at the bottom of the tool. Compared to the conventional method of connecting a screw motor to a mill shoe, this overcomes the problem of the mill shoe not rotating at low speeds, and the mill shoe rotating too fast and having too low torque at high speeds, resulting in both milling and jet well washing failing to achieve the desired results.

[0018] 2) The anti-drop adjustment cap has dual functions of preventing it from falling and adjusting the flow ratio, making the flow rate during tool operation more controllable and adjustment more convenient. The integrated functions save space and cost compared to general technologies.

[0019] 3) The hollow design of the screw rotor allows the flexible shaft to pass through the center, ensuring flexibility while shortening the tool's overall length and reducing the rotor's weight, thereby increasing the tool's cooling effect. This achieves a design that cannot be achieved with current conventional technologies.

[0020] 4) A flow hole is opened at the lower end of the flexible shaft box to reduce the flow ratio and lower the rotor speed, thereby making the entire tool reach a low-speed state.

[0021] 5) According to the actual working conditions, the output speed and torque of the tool can be selected by matching the screw rotor and screw stator head ratio. The optional speed of the tool can be greatly broadened, which is beyond the reach of general technology.

[0022] 6) The metal part of the screw stator is made of alloy steel, the rubber part is made of high-quality imported high-temperature resistant hard rubber, and the screw rotor adopts surface chrome plating or hard alloy spraying process, which has stronger operational adaptability and improves the service life of the tool.

[0023] 7) The use of a rotating dynamic seal effectively prevents fluid leakage and provides stable sealing performance. It prevents fluid from entering the string bearing, directing all fluid flow to the nozzle shaft. This new rotary dynamic seal offsets the flow and pressure relief limitations of an open seal, allowing all fluid and impact forces to escape from the nozzle, resulting in a more powerful impact at the front of the nozzle. Compared to traditional O-ring sealing methods, the rotary dynamic seal provides higher sealing reliability in dynamic operating environments, better adapting to dynamic changes and preventing seal failure due to vibration.

[0024] 8) The water cap and the upper static block, lower static block and lower moving block are made of hard alloy, which is more wear-resistant, corrosion-resistant, high temperature and high pressure-resistant, can withstand greater impact force, and has a lower friction coefficient, can provide smoother rotation and reduce energy loss.

[0025] 9) String bearings have more balls than standard bearings, which evenly distribute the load and can withstand greater shocks and loads. The more balls, the longer the life of the balls and the life of the entire tool.

[0026] 10) Mechanical seals offer superior sealing performance and wear resistance. Compared to conventional seals, they provide better sealing under dynamic conditions, reduce leakage risks, and withstand more extreme operating environments. The overall design is more robust and significantly more durable than conventional seals.

[0027] 11) The nozzle shaft, which combines the milling head and drive shaft, is designed as a single unit for greater convenience, stability, and overall performance. The nozzle shaft not only performs milling but also jets for well flushing. The nozzles on the nozzle shaft can be adjusted to meet specific needs or circumstances. Simply replacing the nozzles to adjust the jet size is simpler than replacing the entire nozzle shaft, saving costs and installation and removal time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural diagram of a low-speed self-rotating milling jet nozzle tool;

[0029] Figure 2 Schematic diagram of the anti-drop adjustment cap, in which 21 is the anti-drop structure and 22 is the flow hole structure;

[0030] Figure 3 It is a schematic diagram of the flexure axis. In the figure, 31. the flow hole;

[0031] Figure 4 It is a schematic diagram of the screw rotor, in which, 41. the inner cavity of the rotor;

[0032] Figure 5 Schematic diagram of a nozzle shaft with circumferentially distributed nozzle holes, in which 51 is a flow channel, 52 is a circumferentially distributed nozzle hole, and 53 is a carbide tooth;

[0033] Figure 6 For the nozzle, in the figure, 61. Water eye.

[0034] Figure 7 Schematic diagram of the nozzle shaft and circumferentially distributed nozzle assembly, 71. Nozzle shaft of circumferentially distributed nozzle, 72. Circumferentially distributed nozzle, 53. Carbide teeth.

[0035] Figure 8 Schematic diagram of water cap, in which 81 is bypass hole.

[0036] Figure 9 Schematic diagram of a tandem bearing, where 91 is the inner ring of the tandem bearing, 92 is the outer ring of the tandem bearing, and 93 is the steel ball.

[0037] Figure 10 Schematic diagram of the nozzle shaft with eccentrically distributed nozzle holes, where 101 is the flow channel of the nozzle shaft with eccentrically distributed nozzle holes, 102 is the eccentrically distributed nozzle holes, and 53 is the carbide teeth.

[0038] Figure 11 Schematic diagram of the nozzle shaft and eccentrically distributed nozzle assembly, 111. Nozzle shaft of eccentrically distributed nozzle, 112. Eccentrically distributed nozzle, 53. Carbide teeth.

[0039] In the figure, 1. upper joint, 2. anti-drop adjustment cap, 3. deflected shaft, 4. screw stator, 5. screw rotor, 6. water cap, 7. adjustment pad, 8. upper static block, 9. shaft housing, 10. string bearing, 11. lower moving block, 12. lower static block, 13. nozzle shaft, 14. nozzle, 15. rotating dynamic seal ring, 16. oiling screw, 17. mechanical seal ring. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments described herein are merely some, and not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments herein without inventive effort are intended to fall within the scope of protection of the present invention.

[0041] Implementation Case 1

[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figure 1 The structure of the present invention is composed of an upper joint 1, an anti-drop adjustment cap 2, a flexible shaft 3, a screw stator 4, a screw rotor 5, a water cap 6, an adjustment pad 7, an upper static block 8, a rotating shaft housing 9, a string bearing 10, a lower moving block 11, a lower static block 12, a nozzle rotating shaft 13, a nozzle 14, a rotating dynamic seal ring 15, an oiling screw 16, a mechanical seal ring 17 and other components.

[0044] The upper joint 1 is connected to the screw stator 4 by a threaded connection, the external spiral of the screw rotor 5 is meshed with the internal spiral of the screw stator 4, the flexible shaft 3 is located in the hollow cavity of the screw rotor 5, and the upper part is connected by a threaded connection. The anti-drop adjustment cap 2 is connected to the upper part of the flexible shaft 3 by a threaded connection, and the water cap 6 is threadedly connected to the lower part of the flexible shaft 3. The upper static block 8 is attached to the outer surface of the water cap 6, and there is a rotating dynamic sealing ring 15 between the water cap 6 and the upper static block 8. A string bearing 10 is installed between the water cap 6 and the lower moving block 11. The inner surface of the lower static block 12 is attached to the outer surface of the lower moving block 11, and there is a mechanical sealing ring 17 between the lower moving block 11 and the lower static block 12. The nozzle shaft 13 is threadedly connected to the lower part of the water cap 6, and the nozzle 14 is fixed in the nozzle hole 52 on the nozzle shaft 13.

[0045] The working principle of the present invention is:

[0046] The circulating fluid in the tool connected above flows into this tool through the upper connector 1. The anti-drop structure 21 of the anti-drop adjustment cap 2 physically prevents the tool from falling off due to vibration or impact. This structure ensures that the tool does not experience axial movement within a limited range during operation, thereby improving the overall reliability and life of the tool string.

[0047] The fluid entering the upper joint has two paths. One path flows through the outside of the anti-drop adjustment cap 2, from the cavity of the upper joint 1 to the cavity below, formed by the difference in the number of rotors. The fluid between the stator and rotor directly enters the lower cavity of the screw stator 4. Under the action of the fluid, the screw rotor 5 rotates.

[0048] The other is flowing through the flow hole 22 inside the anti-drop adjustment cap 2 and into the inner hole of the flexible shaft 3. The fluid passes through the flow hole 31 of the flexible shaft 3 and reaches the inner cavity 41 of the rotor, and then flows into the lower cavity of the screw stator 4.

[0049] The fluids in the two flow channels converge in the lower chamber of the screw stator 4. Under the action of the rotating dynamic seal 15, all the fluid enters the flow channel 51 of the nozzle shaft 13 from the bypass hole 81 of the water cap 6. Under the action of the fluid, the screw rotor 5 drives the flexible shaft 3 to rotate together. The flexible shaft 3, the water cap 6, and the nozzle shaft 13 are connected in series through threads, and the nozzle shaft 13 and the water cap 6 rotate along with the flexible shaft 3. Under the action of the rotating dynamic seal 15, the upper static block 8 is in a stationary state or an ultra-low-speed rotating state. The inner ring 91 of the series bearing is in an interference fit with the nozzle shaft 13 and will rotate with it. The outer ring 92 of the series bearing is in a stationary state or an ultra-low-speed rotating state under the action of the steel ball 93. The lower moving block 11 is threadedly connected to the nozzle shaft 13 and will rotate with it. The lower static block 12 is in a stationary state or an ultra-low-speed rotating state under the action of the mechanical seal 17.

[0050] The fluid that reaches the flow passage of the nozzle shaft 13 is ejected through the nozzle 14 in the nozzle hole 52. The nozzle shaft 13 is milled under the action of rotation and ejects the jet under the action of pressure difference.

[0051] Implementation Case 2

[0052] Based on the first implementation, the flow hole 22 of the anti-drop adjustment cap 3 was enlarged and the ratio of the number of screw stators and rotors was increased. This structure increased the flow rate of the inner cavity 41 of the screw rotor 5 compared to the first implementation. This increased the flow rate of the fluid in the hollow passage 41 of the screw rotor 5, reduced the flow rate between the screw stator 4 and the screw rotor 5, and reduced the rotational speed of the screw rotor 5, thereby achieving a lower speed. After the improvement, test data showed that the tool speed was significantly reduced compared to the first implementation.

[0053] Implementation Case 3

[0054] Case 3 is based on Case 1. In this case, carbide teeth are welded on the top of the nozzle shaft 13 to improve the cutting and milling capabilities of the tool, and increase wear resistance and stability.

Claims

1. A low-speed self-rotating milling jet nozzle tool, characterized by: The upper joint (1) is connected to the screw stator (4) through a thread, the outer spiral of the screw rotor (5) is meshed with the inner spiral of the screw stator (4), the flexible shaft (3) is located in the hollow cavity of the screw rotor (5), the upper part is connected through a thread, the anti-drop adjustment cap (2) is connected to the upper part of the flexible shaft (3) through a thread, and the water cap (6) is connected to the lower part of the flexible shaft (3) through a thread, and the outer surface of the water cap (6) is attached to the upper static block (8), and the water cap (6) and the upper There is a rotating dynamic seal ring (15) between the static block (8), a string bearing (10) is installed between the water cap (6) and the lower moving block (11), the inner surface of the lower static block (12) is in contact with the outer surface of the lower moving block (11), and a mechanical seal ring (17) is provided between the lower moving block (11) and the lower static block (12). The nozzle shaft (13) is threadedly connected to the lower part of the water cap (6), and the nozzle (14) is fixed in the nozzle hole (52) on the nozzle shaft (13).

2. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: The anti-drop adjustment cap (2) has an anti-drop structure (21) and a flow hole (22) structure for adjusting the flow cross-sectional area. The diameter of the flow hole (22) can be adjusted according to the rotation speed requirement.

3. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: The screw rotor (5) is hollow in design, and has a thread inside the upper end that matches the flexible shaft (3), and the flexible shaft (3) is located in the inner cavity (41) of the screw rotor (5), and the upper end of the screw rotor (5) is connected to the upper end of the flexible shaft (3) through a thread.

4. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: A rotating dynamic sealing ring is used between the water cap (6) and the upper static block (8), which can ensure that all fluids enter the nozzle shaft (13) from the bypass hole of the water cap (6).

5. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: A mechanical seal ring (17) is provided between the lower static block (12) and the lower moving block (11).

6. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: The nozzle shaft (13) is provided with at least two nozzle holes (52), in which nozzles (14) are installed. The nozzle holes (52) can be arranged to be eccentrically distributed, and the distance between the central axis of the eccentrically distributed nozzle hole (102) and the axis of the nozzle shaft (13), i.e., the eccentric distance e of the nozzle (14), is between 0 mm and 10 mm.

7. The low-speed self-rotating milling jet nozzle tool according to claim 1, characterized in that: The top of the nozzle shaft (13) is welded with a hard alloy tooth (53).

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