Dual-channel high-low pressure conversion directional hole forming device and use method

Abstract

The invention relates to a dual-channel high-low pressure conversion directional hole forming device and a using method, the dual-channel high-low pressure conversion directional hole forming device comprises a shell and a switching shaft core, the switching shaft core comprises a first fixing sleeve and a second fixing sleeve which are fixed in front of a partition table, and a sliding shaft which is in sealed sliding connection with the inner wall of the partition table, and the front end of the sliding shaft is in sealed sliding connection with the inner wall of the first fixing sleeve; the rear end of the sliding shaft is in sealed sliding connection with the inner wall of the second fixing sleeve, and the rear end of the second fixing sleeve is provided with a water injection opening communicated with the rear area of the sliding shaft; a switching channel is arranged in the sliding shaft, and a water outlet hole, a water inlet hole and a water through hole located between the water outlet hole and the water inlet hole are formed in the side wall of the switching channel. The inner channel and the outer channel are independently designed, the inner channel is responsible for channel switching, the outer channel is responsible for high-pressure and low-pressure power supply, the two channels do not interfere with each other, cooperative proceeding of hole making operation and power driving is achieved, the problem that a traditional device is single in function is solved, and the operation efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the fields of engineering technology such as underground gas extraction and geological disaster control in mines, and in particular to a directional cavity-making device used in conjunction with underground drilling equipment, specifically a dual-channel high-low pressure conversion directional cavity-making device and its usage method. Background Technology

[0002] In the construction of underground gas extraction and coal seam depressurization projects in coal mines, in order to improve gas extraction efficiency and reduce the risk of coal seam outbursts, it is often necessary to perform cavity-making and slotting treatment on the coal body to increase the permeability of the coal body, which is conducive to gas extraction and coal seam depressurization. Therefore, it has become an effective gas control method.

[0003] Currently, for creating cavitation and fractures in coal seams, high-pressure water jet impact is commonly used to break up the coal seam, forming fissures to achieve pressure relief, increased permeability, and enhanced gas extraction. With advancements in water jet technology, the permeability of the impacted coal seam increases, and hydraulic impact technology can also significantly increase the effective extraction radius and improve the efficiency of gas extraction.

[0004] However, existing cavity-making and slotting devices for coal seams mostly adopt a single-channel design, which can only achieve the single function of cavity-making and slotting or power supply, and cannot achieve the integration of cavity-making and power supply. This results in problems of single function and low operating efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a dual-channel high-low pressure conversion directional cavity-creating device and its usage method, which achieves efficient cavity-creating and slit-cutting combined with power supply through dual-channel high-low pressure conversion.

[0006] This invention is achieved through the following technical solution: a dual-channel high-low pressure conversion directional cavity-forming device is provided, comprising a housing and a switching shaft core disposed within the housing. An outer channel is formed between the switching shaft core and the side wall of the housing. A partition platform is fixedly provided on the inner side wall of the housing, and a cavity-forming water spray hole is provided in the partition platform. The switching shaft core includes a first fixed sleeve fixed in front of the partition platform, a second fixed sleeve fixed behind the partition platform, and a sliding shaft that is sealed and slidably connected to the inner wall of the partition platform. The front end of the sliding shaft is sealed and slidably connected to the inner wall of the first fixed sleeve and is connected to the first fixed sleeve by a spring. The rear end of the sliding shaft is sealed and slidably connected to the inner wall of the second fixed sleeve. A water injection port communicating with the area behind the sliding shaft is provided at the rear end of the second fixed sleeve. The sliding shaft is provided with a switching channel. The side wall of the switching channel is provided with a water outlet in front of the partition platform, a water inlet in front of the partition platform, and a water passage between the water outlet and the water inlet. The water inlet is connected to the outer channel behind the partition platform. When the water passage is connected to the cavity-making spray hole, the water outlet is located in the first fixed sleeve. When the water passage is staggered from the cavity-making spray hole, the outer channel in front of the partition platform is connected to the switching channel through the water outlet.

[0007] When the device needs to be moved, this solution forms a water supply channel for the screw motor through the external channel and the switching channel, thereby supplying water to the screw motor. After reaching the designated position, the sliding shaft is pushed by high-pressure water to cut off the connection between the switching channel and the external channel in front of the partition platform, preventing high-pressure water from entering the screw motor. At the same time, the water passage is connected to the cavity-making spray hole, and a jet is formed through the cavity-making spray hole to impact the coal body and complete the cavity-making and slotting operation.

[0008] As an optimization, a positioning platform is fixed to the outer wall of the sliding shaft between the water outlet and the water passage. When the water passage is connected to the cavity-forming spray hole, the front end face of the positioning platform is in contact with the rear end face of the first fixed sleeve; when the rear end face of the positioning platform is in contact with the front end face of the partition platform, the water passage and the cavity-forming spray hole are misaligned, and the outer channel in front of the partition platform is connected to the switching channel through the water outlet. This optimized solution, by setting the positioning platform, facilitates the limitation of the front and rear positions of the sliding shaft, avoids excessive movement of the sliding shaft under the action of high-pressure water or springs, and ensures the reliability of the connection and disconnection state transition between the switching channel and the front outer channel.

[0009] As an optimization, the distance between the positioning platform and the water inlet is greater than the axial length of the partition platform. This optimized design prevents the partition platform from blocking the water inlet when the positioning platform reaches it, thus improving water intake efficiency.

[0010] As an optimization, the switching channel extends forward to the front end of the sliding shaft, and a plug is fixedly connected to the front end of the switching channel via a threaded seal. The plug is rigidly connected to the spring. This optimized design facilitates the machining of the sliding shaft's interior, significantly reduces machining difficulty, and improves manufacturing efficiency.

[0011] As an optimization, a nozzle is installed inside the cavity-forming water spray hole. The inner bore of the nozzle is conical, and the diameter of the nozzle's inner bore facing the switching spindle is larger than the diameter of the other end. This optimized nozzle configuration facilitates increased water pressure and improves the cavity-forming effect.

[0012] As an optimization, a limiting protrusion is fixed to the outer wall of the second fixing sleeve, and a limiting platform is provided on the inner wall of the housing in front of the limiting protrusion, and a slot is provided on the rear side of the limiting protrusion. A hole stop is provided in the slot, and the distance between the limiting platform and the hole stop is adapted to the axial length of the limiting protrusion. This optimized solution uses the hole stop and the limiting platform to axially fix the limiting protrusion, thereby realizing the axial fixation of the second fixing sleeve. The structure is simple and easy to assemble and disassemble.

[0013] As an optimization, the housing includes a front outer shell and a rear outer shell. The outer wall of the front end of the front outer shell is provided with a tapered thread, and the rear end of the front outer shell is fixedly connected to the rear outer shell by a threaded seal. The inner hole of the rear end of the rear outer shell is provided with a tapered thread. This optimized design facilitates the connection between the front end of the housing and the screw motor, as well as the connection between the rear end of the housing and the drill rod, thereby improving assembly efficiency.

[0014] As an optimization, a positioning block is fixed to the outer wall of the first fixing sleeve, and a limiting step is provided on the inner wall of the rear outer shell, located behind the positioning block and adapted to it. The rear end of the front outer shell extends into the inner hole of the rear outer shell and abuts against the front end face of the positioning block. This optimized solution uses the front outer shell and the limiting step to form an axial fixation for the first fixing sleeve, which not only ensures high reliability of the fixation but also facilitates assembly and disassembly.

[0015] As an optimization, a water injection nozzle is sealed and fixed to the rear end of the second fixing sleeve, with the inner hole of the nozzle communicating with the water injection port. This optimized solution, by setting up the water injection nozzle, makes it easier to connect to the high-pressure water injection pipeline, thereby improving installation efficiency.

[0016] This solution also provides a method for using a dual-channel high-low pressure conversion directional cavity creation device, including the following steps: a. Connect the front end of the housing to the screw motor, the rear end of the housing to the drill rod, connect the water inlet to the high-pressure water pump, and connect the outer channel to the clean water pump; b. Start the clean water pump. The water pumped in by the clean water pump enters the screw motor through the outer channel behind the partition, the water inlet, the switching channel, the water outlet and the outer channel in front of the partition in sequence, providing power to the screw motor and driving the device to the designated working position. c. Start the high-pressure water pump and use the high-pressure water to push the sliding shaft forward. The spring is compressed. When the water passage is connected to the cavity-making spray hole, the side wall of the first fixed sleeve blocks the water outlet. The water in the switching channel enters the cavity-making spray hole through the water passage and is sprayed out through the cavity-making spray hole to make cavities and cuts in the coal body. d. After the cavity is created, turn off the high-pressure water pump. The sliding shaft will return to its original position under the action of the spring, and continue to supply water to the screw motor to realize the movement of the device.

[0017] The beneficial effects of this invention are as follows: by setting up internal and external dual channels, the independent and coordinated operation of cavity creation, slit cutting, and power supply is realized, solving the problem of the single function of traditional devices and greatly improving the work efficiency; by axial movement of the sliding shaft, the water in the external channel is blocked and restored, ensuring the pressure concentration during high-pressure cavity creation, the high-pressure water sprayed from the cavity creation nozzle has a stronger cutting force, and the accuracy and efficiency of cavity creation are significantly improved. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the water supply state to the screw motor according to the present invention; Figure 2 This is a schematic diagram of the cavity-forming and slit-cutting state of the present invention; As shown in the figure: 1. First fixing sleeve; 2. Spring; 3. Plug; 4. Water outlet; 5. Water passage hole; 6. Water inlet hole; 7. Second fixing sleeve; 8. Hole stop; 9. Water inlet nozzle; 10. Rear outer shell; 11. Sliding shaft; 12. Switching channel; 13. Nozzle; 14. Front outer shell; 15. Outer channel; 16. Divider platform; 17. Positioning platform; 18. Limiting protrusion; 19. Positioning block; 20. Inner channel. The arrows in the diagram indicate the direction of water flow. Detailed Implementation

[0019] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0020] like Figure 1 The device, a dual-channel high-low pressure switching directional cavity-forming device, includes a housing and a switching shaft disposed within the housing. An outer channel 15 is formed between the switching shaft and the side wall of the housing. A partition platform 16 is fixed to the inner side wall of the housing, and the partition platform is circumferentially closed. A cavity-forming water spray hole is radially penetrating within the partition platform 16. Several cavity-forming water spray holes are evenly arranged circumferentially. In this embodiment, there are three cavity-forming water spray holes. A nozzle 13 is installed within each cavity-forming water spray hole. The inner bore of the nozzle 13 is conical, and the diameter of the nozzle's inner bore facing the switching shaft is larger than the diameter of the other end. The nozzle's inner bore forms a jet hole with a diameter of 1.5mm to 2mm to ensure the jet intensity when high-pressure water is ejected.

[0021] The housing includes a front outer shell 14 and a rear outer shell 10. The front outer wall of the front outer shell 14 is provided with tapered threads, and the rear end of the front outer shell is fixedly connected to the rear outer shell by a threaded seal. The rear inner hole of the rear outer shell 10 is provided with tapered threads. The rear end of the housing is connected to the drill rod through an interface, and the front end of the housing is connected to the screw motor.

[0022] The switching shaft includes a first fixed sleeve 1 fixed to the front of the partition platform, a second fixed sleeve 7 fixed to the rear of the partition platform, and a sliding shaft 11 that is slidably sealed to the inner wall of the partition platform. The first fixed sleeve, the sliding shaft, and the second fixed sleeve are coaxial, ensuring the flexibility of the sliding shaft's axial movement. The front end of the sliding shaft 11 is slidably sealed to the inner wall of the first fixed sleeve and is connected to the first fixed sleeve via a spring 2. The rear end of the sliding shaft is slidably sealed to the inner wall of the second fixed sleeve. In this embodiment, a high-pressure sealing spring is used to ensure a sealing effect.

[0023] Specifically, the first fixed sleeve has an inner hole opening to the rear, and the front end of the sliding shaft extends into the inner hole of the first fixed sleeve, with the inner wall of the first fixed sleeve and the sliding shaft in a sealed sliding contact. The front end of the inner hole of the first fixed sleeve has a fixing groove adapted to the front end of the spring, and the front end of the spring is fixed in the fixing groove. A balance air hole located in front of the sliding shaft is opened on the side wall of the first fixed sleeve to ensure pressure balance when the sliding shaft moves back and forth. A positioning block 19 is fixed on the outer wall of the first fixed sleeve, and a limiting step located behind the positioning block and adapted to the positioning block is provided on the inner wall of the rear outer shell. The inner diameter of the limiting step is smaller than the outer diameter of the positioning block, thus blocking the rearward movement of the positioning block. The rear end of the front outer shell 14 extends into the inner hole of the rear outer shell and abuts against the front end face of the positioning block 19. The rear end face of the positioning block abuts against the front end face of the limiting step, thereby using the front outer shell and the limiting step to fix the first fixed sleeve.

[0024] The second fixed sleeve has a water inlet at its rear end that communicates with the area behind the sliding shaft. The front end of the second fixed sleeve has a sliding groove, into which the rear end of the sliding shaft extends and is sealed against the side wall of the groove. The area between the sliding shaft and the bottom of the sliding groove communicates with the water inlet. The inner hole of the water inlet and the area between the sliding shaft and the bottom of the sliding groove form an inner channel 20. A water nozzle 9 is sealed and fixedly connected to the rear end of the second fixed sleeve. The inner hole of the water nozzle communicates with the water inlet. By providing the water nozzle, it is convenient to connect a high-pressure water input pipe, thus facilitating water injection into the water inlet.

[0025] To facilitate the fixing of the second fixing sleeve, in this embodiment, a limiting protrusion 18 is fixedly provided on the outer side wall of the second fixing sleeve 7. A limiting platform located in front of the limiting protrusion and adapted to the limiting protrusion, and a slot located behind the limiting protrusion are provided on the inner wall of the housing. A hole stop 8 is provided in the slot. The distance between the limiting platform and the hole stop is adapted to the axial length of the limiting protrusion. The inner diameter of the limiting platform and the inner diameter of the hole stop are both smaller than the outer diameter of the limiting protrusion. The hole stop and the limiting platform are used to axially fix the limiting protrusion, thereby realizing the axial fixing of the second fixing sleeve. The structure is simple and easy to disassemble and assemble.

[0026] The sliding shaft has a switching channel 12. The side wall of the switching channel has a water outlet 4 located in front of the partition platform, a water inlet 6 located behind the partition platform, and a water passage 5 located between the water outlet and the water inlet. The water inlet 6 communicates with the outer channel behind the partition platform. When the sliding shaft moves to the point where the water passage 5 communicates with the cavity-creating spray hole, the water outlet is located within the first fixed sleeve. When the sliding shaft moves to the point where the water passage and the cavity-creating spray hole are misaligned, the outer channel in front of the partition platform communicates with the switching channel through the water outlet.

[0027] A positioning platform 17 is fixedly installed on the outer wall of the sliding shaft between the water outlet and the water passage. When the water passage is connected to the cavity-forming spray hole, the front end face of the positioning platform 17 is in contact with the rear end face of the first fixed sleeve 1. When the rear end face of the positioning platform is in contact with the front end face of the partition platform, the water passage 5 is offset from the cavity-forming spray hole, and the outer channel in front of the partition platform is connected to the switching channel through the water outlet. The distance between the positioning platform 17 and the water passage 5 is greater than the axial length of the partition platform 16, so that when the rear end face of the positioning platform is in contact with the front end face of the partition platform, the water passage 5 and the water inlet 6 are simultaneously connected to the switching channel and the outer channel behind the partition platform. The flow area of ​​the water inlet is not less than 5 times the flow area of ​​the water passage to ensure the jet pressure, and the flow area of ​​the water outlet is not less than the flow area of ​​the water inlet.

[0028] For ease of processing, the switching channel 12 in this embodiment extends forward to the front end face of the sliding shaft. The front end of the switching channel is fixedly connected to a plug 3 by a threaded seal, and the plug 3 is rigidly connected to the spring 2.

[0029] To improve sealing performance, this embodiment provides sealing rings between the front outer shell 14 and the rear outer shell 10, between the sliding shaft and the second fixed sleeve, and between the water inlet and the water outlet.

[0030] The housing in this embodiment is made of high-strength alloy steel to ensure the structural strength of the device under complex downhole conditions. The inner and outer channels are arranged parallel to each other along the axial direction of the housing. The diameter of the inner channel is designed according to the high-pressure water pressure requirements, and the diameter of the outer channel matches the power requirements of the screw motor. The high-pressure sealing spring is made of high-pressure resistant and fatigue-resistant spring steel. The sliding shaft is made of wear-resistant alloy material and slides in cooperation with the inner walls of the first and second fixed sleeves to ensure smooth movement.

[0031] This embodiment features a dual-channel structure where the two channels operate independently, each performing a different function. The inner channel is a high-pressure channel specifically designed to introduce high-pressure water. This water propels a sliding shaft through the inner channel, compressing a spring and forcing water from the outer channel through a water jet orifice to create cavitation. The high-pressure water transmitted through the outer channel is then ejected at high speed through the jet orifice, forming a concentrated jet that precisely and efficiently cuts and creates cavitation in the target coal body, ensuring effective cavitation.

[0032] When high-pressure water is introduced into the inner channel, its pressure drives the sliding shaft and spring to move together. After the sliding shaft moves, it uses the side wall of the first fixed sleeve to block the water passage of the screw motor in the outer channel, causing the screw motor in the outer channel to temporarily stop water flow. At this time, the device concentrates power and high-pressure water to perform high-pressure cavity creation. After the cavity is created, the pressure in the inner channel decreases, and the sliding shaft returns to its original position under the action of the spring's restoring force. The screw motor in the outer channel resumes water flow and the screw motor operates normally, achieving seamless switching between high and low pressure conversion and operating modes.

[0033] The casing has standard interfaces at both ends, compatible with existing downhole drilling equipment components such as drill pipes and screw motors, offering high versatility and allowing for immediate use without additional modifications. The high-pressure water inlet of the inner channel connects to a high-pressure water pump, while the clean water inlet of the outer channel connects to a clean water pump. During operation, the clean water pump starts, pumping water through the outer channel to power the screw motor, driving the device to the designated working position. Subsequently, the high-pressure water pump is started, allowing high-pressure water to flow into the inner channel. The pressure pushes the sliding shaft, compressing the high-pressure sealing spring, causing the first fixed sleeve to block water flow to the screw motor in the outer channel. This switches to high-pressure water being ejected at high speed through the jet orifice to create cavities and cut slots in the coal seam. After cavitation is complete, the high-pressure water pump is shut off, the pressure in the inner channel decreases, the high-pressure sealing spring resets, pushing the sliding shaft back to its original position, water flow resumes in the outer channel, and the screw motor drive moves to the next working position, repeating the cavitation operation cyclically.

[0034] Specifically, the method of using a dual-channel high-low pressure conversion directional cavitation device in this embodiment includes the following steps: a. Connect the front end of the housing to the screw motor, the rear end of the housing to the drill rod, connect the water inlet to the high-pressure water pump, and connect the outer channel to the clean water pump; b. Start the clean water pump. The water pumped in by the clean water pump enters the screw motor through the outer channel behind the partition, the water inlet, the switching channel, the water outlet and the outer channel in front of the partition in sequence, providing power to the screw motor and driving the device to the designated working position. c. Start the high-pressure water pump and use the high-pressure water to push the sliding shaft forward. The spring is compressed. When the water passage is connected to the cavity-making spray hole, the side wall of the first fixed sleeve blocks the water outlet. The water in the switching channel enters the cavity-making spray hole through the water passage and is sprayed out through the cavity-making spray hole to make cavities and cuts in the coal body. d. After the cavity is created, turn off the high-pressure water pump. The sliding shaft will return to its original position under the action of the spring, and continue to supply water to the screw motor to realize the movement of the device.

[0035] Compared with the prior art, the present invention has the following significant technical effects: 1. It adopts an independent internal and external dual-channel design with coordinated functions: the internal channel is responsible for channel switching, and the external channel is responsible for high and low voltage power supply. The two channels do not interfere with each other, realizing the coordinated operation of hole making and power drive, solving the problem of single function of traditional devices and greatly improving operation efficiency.

[0036] 2. Precise high and low pressure conversion, efficient cavity creation: The sliding shaft and spring are driven by high pressure water in the inner channel to block and restore the flow of high and low pressure water in the outer channel, ensuring pressure concentration during high pressure cavity creation. The high pressure water ejected from the jet hole has a stronger cutting force, and the accuracy and efficiency of cavity creation are significantly improved.

[0037] 3. Excellent sealing performance and long service life: The spring configured in the inner channel is a high-pressure sealing spring, which has a reliable sealing effect and a service life that is more than 30% longer than that of traditional spring structures.

[0038] 4. High versatility and easy operation: The device adopts a standard interface and can be directly used with existing drilling equipment. It is easy to install and disassemble and does not require additional modification by professional personnel, which reduces the difficulty of operation and construction costs.

[0039] 5. Stable operation and high safety: The dual-channel separation design avoids interference from high and low pressure water to the power system, ensuring stable power supply from the screw motor. The device experiences low vibration and high stability during operation, while also reducing the risk of leakage and improving the safety of downhole operations.

[0040] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A dual-channel high-low pressure conversion directional cavitation device comprising a housing, characterized in that: The switching shaft core is arranged in the shell, and an outer channel (15) is formed between the switching shaft core and the shell side wall. The switching shaft core comprises a first fixed sleeve (1) fixed in front of the partition table, a second fixed sleeve (7) fixed behind the partition table, and a sliding shaft (11) sealingly and slidably connected with the inner wall of the partition table. The sliding shaft is internally provided with a switching channel (12), and the side wall of the switching channel is provided with a water outlet hole (4) located in front of the partition table, a water inlet hole (6) located behind the partition table, and a water passing hole (5) located between the water outlet hole and the water inlet hole.

2. The dual channel high-low pressure converting directional cavitation device of claim 1, wherein: When the water passing hole (5) is communicated with the hole-forming water spraying hole, the water outlet hole is located in the first fixed sleeve. When the water passing hole is misaligned with the hole-forming water spraying hole, the outer channel in front of the partition table is communicated with the switching channel through the water outlet hole.

3. The dual channel high-low pressure converting directional cavitation device of claim 2, wherein: The distance between the positioning table (17) and the water passing hole (5) is greater than the axial length of the partition table (16).

4. The dual channel high-low pressure converting directional cavitation device of claim 2, wherein: The switching channel (12) penetrates to the front end face of the sliding shaft, and the front end of the switching channel is sealingly and fixedly connected with a plug (3) through threads.

5. The dual channel high-low pressure converting directional cavitation device of claim 1, wherein: The hole-forming water spraying hole is internally provided with a nozzle (13), the inner hole of the nozzle (13) is tapered, and the hole diameter of the inner hole of the nozzle towards one end of the switching core shaft is greater than the hole diameter of the other end.

6. The dual channel high-low pressure converting directional cavitation device of claim 1, wherein: The outer side wall of the second fixed sleeve (7) is fixedly provided with a limiting protrusion (18), the inner wall of the shell is provided with a limiting table located in front of the limiting protrusion and a clamping groove located behind the limiting protrusion, a hole stop (8) is arranged in the clamping groove, and the distance between the limiting table and the hole stop is matched with the axial length of the limiting protrusion.

7. The dual channel high-low pressure converting directional cavitation device of claim 1, wherein: The shell comprises a front shell (14) and a rear shell (10), the front end of the front shell (14) is provided with a tapered thread, the rear end of the front shell is sealingly and fixedly connected with the rear shell through threads, and the rear end inner hole of the rear shell (10) is provided with a tapered thread.

8. The dual channel high-low pressure converting directional cavitation device of claim 7, wherein: The outer side wall of the first fixed sleeve is fixedly provided with a positioning block (19), the inner wall of the rear shell is provided with a limiting step located behind the positioning block and matched with the positioning block, and the rear end of the front shell (14) extends into the inner hole of the rear shell and abuts against the front end face of the positioning block (19).

9. The dual channel high-low pressure converting directional cavitation device of claim 1, wherein: The rear end of the second fixed sleeve is sealingly and fixedly connected with a water injection nozzle (9), and the inner hole of the water injection nozzle is communicated with the water injection port.

10. The method of using a dual channel high-low pressure conversion directional cavitation device according to any one of claims 1-9, wherein, The steps comprise: a. connecting the front end of the shell with a screw motor, connecting the rear end of the shell with a drill rod, connecting the water injection port with a high-pressure water pump, and connecting the outer channel with a clean water pump. b. Start the clean water pump, the water pumped by the clean water pump enters the screw motor in turn through the outer channel behind the partition table, the water inlet hole, the switching channel, the water outlet hole and the outer channel in front of the partition table, providing power for the screw motor, and driving the device to reach the designated working position; c. Start the high-pressure water pump, use high-pressure water to push the sliding shaft forward, the spring is compressed, when the water hole is communicated with the hole-making water jet hole, the side wall of the first fixed sleeve forms a block to the water outlet hole, the water in the switching channel enters the hole-making water jet hole through the water hole, and is sprayed out through the hole-making water jet hole, and the coal body is hole-making and slotting; d. After the hole-making is completed, the high-pressure water pump is closed, the sliding shaft is reset backward under the action of the spring, and water continues to be supplied to the screw motor, realizing the movement of the device.

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