Pressure relief anti-reflection device capable of realizing adjustable coal seam reaming radius

Abstract

The utility model belongs to the technical field of coal seam gas extraction, chambering, pressure relief and permeability increase, and particularly relates to a pressure relief and permeability increase device capable of adjusting the coal seam chambering radius, which comprises a gas driving component and a drilling machine, an output shaft of the drilling machine is rotatably connected with a folding sleeve component through a bearing, and a drill bit is arranged at the tail end of the folding sleeve component. The folding sleeve assembly comprises a sleeve shell, two symmetrical arc-shaped notches are formed in the tail end of the sleeve shell, two parallel through central flow channels and an inner partial pressure hole pipe are arranged in the sleeve shell, one end of the inner partial pressure hole pipe is communicated with the high-pressure air pipe, and the other end of the inner partial pressure hole pipe is communicated with the central flow channels through two air flow channels. A pushing device is arranged in the central runner, and a reaming assembly is arranged at the tail end of the pushing device; the gas driving assembly controls the pushing device to be located at different positions in the flexible cutter, so that the cutter accurately extends out by the fixed length of the flexible cable chain under different air pressures.

Description

Technical Field

[0001] This utility model belongs to the field of coal seam gas extraction, borehole expansion and pressure relief and permeability enhancement technology, and in particular relates to a pressure relief and permeability enhancement device that enables adjustable borehole radius in coal seams. Background Technology

[0002] Coal, as my country's basic energy source and industrial raw material, has long provided a strong guarantee for economic and social development and the stable supply of national energy security. Efficient gas drainage is a crucial requirement for releasing coal production capacity and ensuring a safety net for energy. To address the issue of the inaccurate adjustment of the borehole radius by mechanical cutters during borehole reaming operations, traditional mechanical cutters have a fixed reaming radius. However, the reaming radius should be matched with parameters such as coal seam strength and ground stress; therefore, an excessively large or small reaming radius will not achieve optimal gas drainage results. Thus, maintaining precise control and fixation of the cutter length during borehole reaming operations is a necessary prerequisite for efficient coal breaking and efficient gas drainage.

[0003] To overcome the bottlenecks in pressure relief and permeability enhancement technology and achieve more efficient coal seam gas extraction, patent CN202210037215.5 discloses "A pneumatic flexible cutter coal-breaking, pressure-relief, and permeability enhancement device and method in soft coal seams." This method utilizes an air compressor to convert air pressure energy into the angular kinetic energy of a flexible cutter, driving the cutter to rotate at high speed and break the coal, thus solving the problems of "hole collapse" and "drill jamming" caused by unevenness in traditional hole-expanding methods. However, this technology cannot precisely control and adjust the extension and retraction length of the flexible chain, resulting in low hole-expanding efficiency of the flexible cutter and consequently low gas extraction efficiency. Therefore, a method using a locking device in conjunction with a pushing device is proposed to precisely control the extension and retraction length of the flexible chain of the flexible cutter. A retraction mechanism precisely controls the cutter's extension length, achieving gradual hole expansion and optimizing the hole radius, thereby achieving the goal of pressure relief, permeability enhancement, and improved gas extraction in coal seams. Utility Model Content

[0004] The purpose of this invention is to provide a pressure relief and permeability enhancement device that enables adjustable borehole radius in coal seams. By controlling the air pressure, the device is pushed to different positions inside the flexible cutter, allowing the cutter to precisely extend a fixed length of flexible chain under different air pressures.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A pressure-relief and permeability-enhancing device for adjusting the borehole radius in coal seams includes a gas-driven assembly and a drilling rig. The output shaft of the drilling rig is rotatably connected to a retractable sleeve assembly via bearings. A torque sensor and a tachometer are mounted on the rotating output shaft of the drilling rig. A drill bit is provided at the end of the retractable sleeve assembly. The retractable sleeve assembly includes a sleeve housing with two symmetrical arc-shaped slots at its end. The sleeve housing contains two parallel through-flow central channels and an internal pressure-distributing pipe. One end of the internal pressure-distributing pipe is connected to a high-pressure gas pipe, and the other end is connected to the central channels via two airflow channels. A pushing device is provided in the central channels, and a borehole-enhancing assembly is provided at the end of the pushing device. The arc-shaped slots are connected to the central channels for the borehole-enhancing assembly to extend or retract.

[0007] Furthermore, a threaded cap is provided at the left end of the central flow channel, and a threaded pin is provided at the right end of the threaded cap. A tension spring is provided on the threaded pin, and the right end of the tension spring is connected to the pushing device. The threaded cap and the central flow channel are connected by a threaded seal. The length of the inner pressure dividing hole tube is less than the length of the tension spring in its natural state. This arrangement facilitates the direct application of high-pressure gas to the pushing device.

[0008] Furthermore, the pushing device includes a single-sided threaded pushing device and multiple double-sided threaded pushing devices connected in sequence. The single-sided threaded pushing device includes a horizontally arranged central shaft, the left end of which is connected to a spring. A retaining ring, a slider, and a pushing baffle are sequentially mounted on the central shaft from left to right. The outer diameters of the slider and the pushing baffle match the central flow channel. Both sides of the slider have arc-shaped protrusions. The left side of the pushing baffle matches the arc-shaped protrusion, and the right side also has an arc-shaped protrusion. The right end of the central shaft is threaded. The double-sided threaded pushing device, based on the single-sided threaded pushing device, has a central... The left end of the shaft is also threaded; the single-sided threaded pushing device and the double-sided threaded pushing device are connected by a flexible base and an asymmetrical link, the length of the double-sided threaded pushing device to the flexible base and the asymmetrical link is 8cm; a retaining ring is clipped on one side of the pushing device, serving as a limit, and is connected to the tension spring; the pushing baffle is integrated with the central shaft, serving as a sealing air pressure, and is connected to the flexible chain; the slider is located between the retaining ring and the pushing baffle, and can slide on the central shaft; the pushing baffle, combined with the locking device, controls the extension and retraction length of the flexible chain, and high-pressure gas enters the high-pressure air pipe through the output end of the air compressor, and then... High-pressure gas enters the central flow channel of the flexible cutter's retractable sleeve through a high-pressure gas pipe; the high-pressure gas pushes the pusher baffle, causing the entire flexible chain to flow out of the retractable sleeve slot, at which point the tension spring in the central flow channel is under stress; during the movement of the pushing device, when the pusher baffle approaches the lower short side of the trapezoidal limiting device, the pusher baffle causes the trapezoidal limiting device to compress the spring inside the through hole, causing the pusher baffle to pass over the trapezoidal limiting device, and the trapezoidal limiting device is ejected and restored by the spring inside the through hole; at this time, the pusher baffle will be stuck on the lower long side of the trapezoidal limiting device, thus fixing the extension and retraction length of the flexible chain; increasing atmospheric pressure, pushing... The slider on the drive shaft is pushed to the retaining spring of the push device by the trapezoidal limiting device. When the slider stops moving at the retaining spring, the trapezoidal limiting device will pass the slider, compressing the spring inside the hole. After the locking device passes the slider, the spring inside the hole is compressed and returns to its original position, and the trapezoidal limiting device extends. If the air pressure is increased, the trapezoidal limiting device can pass the subsequent push devices, achieving precise control of the extension length of the flexible chain. If the air pressure is decreased, the push device can move in the opposite direction of the arc-shaped slot, and the trapezoidal limiting device is fixed at the push baffle of the moved push device, achieving precise control of the extension and retraction of the flexible chain. When the air pressure is stopped, the central flow channel tension spring returns to its original position, pulling the flexible chain back to its original position. At this time, the locking device pushes the slider towards the push baffle. When the slider and the push baffle are tightly fitted, the spring inside the hole is compressed, the locking device passes the slider and the push baffle, and after passing, the spring inside the hole returns to its original position, and the trapezoidal limiting device returns to its original position.

[0009] Furthermore, the right end of the sleeve housing is provided with two sets of through holes on the left side of the arc-shaped groove. The deep part of the through holes is a cylindrical space, and the shallow part is a threaded cylindrical space. There are two through holes in each set, which are perpendicular to the central flow channel and connected to it. Each through hole is provided with a locking device, which matches the through hole. Each locking device includes a locking screw, and a spring is provided at the bottom of the locking screw. A trapezoidal limiting device is provided at the bottom of the spring. The lower end of the trapezoidal limiting device is a column, and the upper end is a flat cylinder with a slotted cutter. The long side of the lower column of the trapezoidal limiting device is located at the right end, and the short side of the lower column of the trapezoidal limiting device is located at the left end. In use, the locking device is first inserted into one of the through holes, then the spring is inserted, and then the locking screw is inserted. The locking screw has threads, so that it fits tightly with the threads of the through hole. Since the locking screw is fixed, when the trapezoidal limiting device is subjected to force, the middle spring is compressed, causing the trapezoidal limiting device to move.

[0010] Furthermore, the hole-enlarging assembly includes a flexible tool chain and a tool head assembly located at the end of the flexible tool chain. The flexible tool chain includes multiple asymmetrical links connected end to end. A central block is located between adjacent asymmetrical links. The central block is a cube, and a through hole is provided on each of its four sides. The central block is placed between two asymmetrical links, and the links are fixedly connected by embedding the cross shaft into the through hole.

[0011] Furthermore, the cutter head assembly includes a cutter head base and a cutter head located on the cutter head base. The cutter head base is provided with a plurality of holes for mounting the cutter head, and both the cutter head base and the cutter head are provided with cutter heads.

[0012] This device enables adjustable hole enlargement radius control: When the trapezoidal limiting device is fixed at a certain pushing baffle, the flexible cutter enlarges the hole with radius R1. If the air pressure is increased by a certain value, the tension spring in the central flow channel extends, causing several pushing devices and flexible chains to move in the direction of the arc-shaped groove. The pushing device that has not passed the trapezoidal limiting device and is closest to the trapezoidal limiting device passes the trapezoidal limiting device as the air pressure increases, and the trapezoidal limiting device will be fixed at the pushing baffle that has just passed the trapezoidal limiting device. At this time, the extended length of the flexible chain is the sum of the length of the pushing device and the length of one section of flexible chain at the connection between the pushing devices, totaling 8cm. At this time, the flexible cutter enlarges the hole with radius R2. By further increasing the air pressure, the trapezoidal limiting device can pass over the next pushing device and be fixed at the next pushing baffle. The extension length of the flexible chain increases by 8cm. Continuing to increase the air pressure allows the trapezoidal limiting device to pass over subsequent pushing devices and be fixed at the pushing baffle of those devices. The extension length of the flexible chain increases by 8cm for each pushing device it passes over. At this point, the flexible cutter moves at a radius R... nThe hole is enlarged until the trapezoidal limiting device is fixed at the push baffle of the last push device, which allows for precise extension of the enlarged hole radius. If precise contraction of the enlarged hole radius is required, when the trapezoidal limiting device is fixed at a certain push baffle (assuming that the push device is a single-sided threaded push device A, which is connected to the double-sided threaded push device B and the double-sided threaded push device C in the direction of the arc-shaped groove), the air pressure is slightly increased at this air pressure value, so that the trapezoidal limiting device passes the slider of this push device A. Then the air pressure is reduced, and the tension spring contracts, causing the push device and the flexible chain to move in the opposite direction of the arc-shaped groove. The entire push device that previously fixed the trapezoidal limiting device will return to the side of the trapezoidal limiting device in the opposite direction of the arc-shaped groove. If a contraction of 8cm is required, the trapezoidal limiting device can pass the previous push device A and then pass the next push device B. At this time, the trapezoidal limiting device is located between the push baffle of push device B and the slider of push device C. Slightly increase the air pressure to move the pushing device B towards the arc-shaped slot. When the trapezoidal limiting device passes the pushing baffle of the pushing device B, the air pressure can be shut off to fix it in place. At this point, the flexible chain retracts to a length of 8cm, which allows for precise shrinkage of the hole radius.

[0013] The advantages of this utility model are:

[0014] 1. This utility model proposes a pressure relief and permeability enhancement device that enables precise adjustment of the coal seam borehole radius, featuring precise control of the flexible cutter extension length, stable extension length, and automatic retraction;

[0015] 2. The utility model locking device, in conjunction with the pushing device, can fix the pushing baffle at the trapezoidal limiting device, and the flexible cutter's extension length can be precisely controlled and the extension length is stable;

[0016] 3. The multi-stage pushing device, consisting of a single-sided threaded pushing device and a double-sided threaded pushing device, can more accurately control the extension length of the flexible tool. In addition, the sliding block of the pushing device and the trapezoidal limiting device work together to achieve the feature of automatic retraction of the flexible tool after extension.

[0017] 4. Flexible cutting tool: At the joints of the flexible cable, the central block and the cross shaft maintain the flexibility of the flexible cable while ensuring the strength between the links.

[0018] 5. The flexible cutter and hemispherical cutter head at the end of the flexible chain enable efficient coal breaking and gas extraction during the integrated drilling and expansion process. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0020] Figure 2This is a schematic diagram of the structure of the sleeve shell of this utility model.

[0021] Figure 3 This is a schematic diagram of the retractable sleeve assembly in this utility model.

[0022] Figure 4 This is a schematic diagram of the internal high-pressure gas flow structure of the flexible cutting tool of this utility model.

[0023] Figure 5 This is a schematic diagram of the locking device structure of this utility model, wherein a is a schematic diagram of the overall structure; b is a schematic diagram of the limiting device structure; and c is a schematic diagram of the locking screw structure.

[0024] Figure 6 This is a schematic diagram of the pushing device in this utility model, wherein a is a schematic diagram of the single-sided threaded pushing device; b is a schematic diagram of the double-sided threaded pushing device; c is a schematic diagram of the pushing baffle; d is a schematic diagram of the slider; and e is a schematic diagram of the snap ring.

[0025] Figure 7 This is a diagram illustrating the interaction between the pushing device and the trapezoidal limiting device.

[0026] Figure 8 This is a flowchart illustrating the interaction between the pushing device and the trapezoidal limiting device.

[0027] Figure 9 This is a schematic diagram of the overall structure of a flexible tool chain.

[0028] Figure 10 yes Figure 9 The enlarged view shows a portion of the structure, where a is a schematic diagram of the flexible base structure and b is a schematic diagram of the chain link structure.

[0029] Figure 11 These are schematic diagrams of the central block and cross shaft between the links; where a is a schematic diagram of the central block structure; and b is a schematic diagram of the cross shaft structure.

[0030] Figure 12 This is a schematic diagram of the cutter head structure of this utility model; wherein, a) is a schematic diagram of the overall structure of the cutter head; b) is a schematic diagram of the cutter head structure; and c) is a schematic diagram of the cutter head base structure.

[0031] In the diagram: 1. Air compressor; 2. High-pressure air pipe; 3. Drill rig; 4. Drill rig output shaft; 5. Retractable sleeve assembly; 6. Drill bit; 7. Central flow channel; 8. Internal pressure distribution hole pipe; 9. Arc-shaped groove; 10. Through hole; 11. Airflow channel; 12. Tension spring; 13. Threaded shaft pin; 14. Threaded cap; 20. Single-sided threaded push device; 21. Snap ring; 22. Slider; 23. Push baffle; 30. Locking device; 31. Trapezoidal limit device; 32. Spring; 33. Locking screw; 40. Central block; 41. Through hole in central block; 42. Cross shaft; 50. Cutting head; 51. Cutting head head; 52. Cutting head base; 61. Flexible base; 62. Chain link; 201. Double-sided threaded push device. Detailed Implementation

[0032] like Figure 1-12As shown, a pressure relief and permeability enhancement device for adjusting the borehole radius in coal seams includes an air compressor 1, a high-pressure air pipe 2 connected to the air compressor, and a drilling rig 3. The output shaft 4 of the drilling rig is rotatably connected to a retractable sleeve assembly 5 via bearings. A torque sensor and a tachometer are mounted on the rotating output shaft of the drilling rig. A drill bit 6 is provided at the end of the retractable sleeve assembly. The retractable sleeve assembly includes a sleeve shell with two symmetrical arc-shaped slots 9 at the end. The sleeve shell contains two parallel through-flow central channels 7 and an internal pressure-distributing pipe 8. One end of the internal pressure-distributing pipe 8 is connected to the high-pressure air pipe 2, and the other end is connected to the central channels via two airflow channels. A pushing device is provided in the central channel, and a borehole expansion assembly is provided at the end of the pushing device. The arc-shaped slots are connected to the central channels for the borehole expansion assembly to extend or retract.A threaded cap 14 is provided at the left end of the central flow channel, and a threaded pin 13 is provided at the right end of the threaded cap. A tension spring 12 is provided on the threaded pin, and the right end of the tension spring is connected to the pushing device. The threaded cap and the central flow channel are connected by a threaded seal. The length of the inner pressure dividing hole tube is less than the length of the tension spring in its natural state. This arrangement facilitates the direct application of high-pressure gas to the pushing device. The pushing device includes a single-sided threaded pushing device 20 and multiple double-sided threaded pushing devices 201 connected in sequence. The single-sided threaded pushing device includes a horizontally arranged central shaft. The left end of the central shaft is connected to the spring. From left to right, a retaining ring 21, a slider 22, and a pushing device are sequentially mounted on the central shaft. Baffle 23, the outer diameter of the slider and the push baffle matches the central flow channel, the left and right sides of the slider are arc-shaped convex surfaces, the left side of the push baffle matches the arc-shaped convex surface, and the right side is also an arc-shaped convex surface, the right end of the central shaft is threaded; the double-sided threaded push device is based on the single-sided threaded push device and also has threads machined on the left end of the central shaft; the single-sided threaded push device and the double-sided threaded push device are connected by a flexible base 61 and an asymmetric link 62, the length of the double-sided threaded push device to the flexible base and the asymmetric link is 8cm; a retaining ring is clipped on one side of the push device, which plays a limiting role and is connected to the tension spring; the push baffle is integrated with the central shaft, which plays a sealing air pressure role and is connected to the flexible cable The chain is connected; the slider is located between the retaining ring and the push baffle, and can slide on the central shaft; the push baffle, in conjunction with the locking device, controls the extension and retraction length of the flexible chain; high-pressure gas enters the high-pressure air pipe through the output end of the air compressor, and then enters the central flow channel of the flexible cutter retracting sleeve through the high-pressure air pipe; the high-pressure gas pushes the push baffle, causing the entire flexible chain to flow out towards the groove of the retracting sleeve, at which point the tension spring in the central flow channel is under force; during the movement of the pushing device, when the end of the push baffle is close to the lower short side of the trapezoidal limiting device, the push baffle will cause the trapezoidal limiting device to compress the spring inside the through hole, causing the push baffle to pass over the trapezoidal limiting device, and the trapezoidal limiting device will be ejected and restored by the spring inside the through hole; at this time, the push... The baffle will lock onto the lower long side of the trapezoidal limiting device, fixing the extension and retraction length of the flexible chain. With increased air pressure, the slider on the push device shaft will be pushed by the trapezoidal limiting device to the push device's retaining spring. When the slider stops moving at the retaining spring, the trapezoidal limiting device will pass the slider, compressing the spring inside the perforation. After the locking device passes the slider, it will compress and restore the spring inside the perforation, allowing the trapezoidal limiting device to extend. If the air pressure continues to increase, the trapezoidal limiting device can pass over subsequent push devices, achieving precise control of the flexible chain's extension length. If the air pressure decreases, the push device can move in the opposite direction of the arc-shaped slot, and the trapezoidal limiting device will be fixed at the push baffle of the moved push device, achieving precise control of the flexible chain's extension and retraction.When the air pressure is stopped, the central flow channel tension spring returns to its original position. Pull the flexible chain back to its original position. At this time, the locking device pushes the slider to move towards the push baffle. When the slider and the push baffle are tightly fitted, the spring in the through hole is compressed. The locking device passes over the slider and the push baffle. After passing over, the spring in the through hole returns to its original position, and the trapezoidal limit device returns to its original position. The right end of the sleeve housing has two sets of through holes 10 located to the left of the arc-shaped groove. The deep part of the through hole is a cylindrical space, and the shallow part is a threaded cylindrical space. Each set of through holes consists of two holes, which are perpendicular to and connected to the central flow channel. Each through hole contains a locking device 30, which matches the through hole. Each locking device includes a locking screw 33, and a spring 32 is located at the bottom of the locking screw. A trapezoidal limiting device 31 is located at the bottom of the spring. The lower end of the trapezoidal limiting device is a column, and the upper end is a flat cylinder with a slotted cutter. The long side of the lower column of the trapezoidal limiting device is located at the right end, and the short side is located at the left end. In use, the locking device is first inserted into one of the through holes, then the spring is inserted, and then the locking screw is inserted. The locking screw has threads, which make it fit tightly with the threads of the through hole. Since the locking screw is fixed, when the trapezoidal limiting device is subjected to force, the middle spring is compressed, causing the trapezoidal limiting device to move. The hole-reaming assembly includes a flexible tool chain and a tool head assembly located at the end of the flexible tool chain. The flexible tool chain includes multiple asymmetrical links 62 connected end to end. Between adjacent asymmetrical links is a central block 40. The central block is a cube, and each of its four sides has a central block through hole 41. The central block is placed between two asymmetrical links, and the links are fixedly connected by a cross shaft 42 embedded in the central block through hole. The tool head assembly includes a tool head base 52 and a tool head 51 located on the tool head base. The tool head base has multiple holes for mounting the tool head, and both the tool head base and the tool head have multiple uniformly arranged carbide tools 50.

[0033] Another objective of this utility model is to provide a pressure relief and permeability enhancement device and method for achieving precise adjustment of the coal seam borehole radius, comprising the following steps:

[0034] S1. In the initial state, the air compressor, high-pressure air pipe and drilling machine are connected, and the hole expansion assembly is retracted into the retracting sleeve assembly;

[0035] S2. Input 0.8MPa air pressure into the inner pressure distribution hole tube, stretch the spring initially to unfold the cutter, and stabilize it at this length. Control the rotation speed to 300 rpm to rotate and enlarge the hole in the coal seam until the entire hole enlargement is completed.

[0036] S3. Increase the air pressure and input 1.1 MPa air pressure into the inner pressure distribution hole pipe. The tension spring extends further to expand the cutter by 8cm, which is the length of a section of double-sided threaded push device, flexible base and asymmetric chain link, and stabilizes at this length. The extension length of the flexible cutter is achieved by controlling the pressure of the compressor. The rotation speed is controlled at 300 rpm to rotate and expand the hole in the coal seam until the entire hole is expanded.

[0037] S4. Increase the air pressure and input 1.4 MPa air pressure into the inner pressure distribution hole pipe. After the air pressure is turned off, the flexible cutter chain is retracted into the retracting sleeve. After the hole enlargement and permeability enhancement of one coal hole is completed, the equipment is withdrawn and preparations are made for drilling other holes.

[0038] S5. Repeat steps S2-S4 until all boreholes have been drilled, enlarged, depressurized, and permeable.

Claims

1. A pressure-relief and permeability-enhancing device for achieving adjustable coal seam borehole radius, characterized in that: The device includes a gas-driven assembly and a drilling rig. The output shaft of the drilling rig is rotatably connected to the retracting sleeve assembly via a bearing. The retracting sleeve assembly has a drill bit at its end. The retracting sleeve assembly includes a sleeve housing. The end of the sleeve housing has two symmetrical arc-shaped slots. The sleeve housing has two parallel through-flow central channels and an internal pressure-distributing pipe. One end of the internal pressure-distributing pipe is connected to a high-pressure gas pipe, and the other end is connected to the central channels via two airflow channels. A pushing device is provided in the central channel, and a hole-expanding assembly is provided at the end of the pushing device.

2. The pressure relief and permeability enhancement device for achieving adjustable coal seam borehole radius as described in claim 1, characterized in that: A threaded cap is provided at the left end of the central flow channel, and a threaded pin is provided at the right end of the threaded cap. A tension spring is provided on the threaded pin, and the right end of the tension spring is connected to the pushing device. The threaded cap and the central flow channel are sealed together. The length of the inner pressure dividing hole tube is less than the length of the tension spring in its natural state.

3. The pressure relief and permeability enhancement device for achieving adjustable coal seam borehole radius as described in claim 2, characterized in that: The pushing device includes a single-sided threaded pushing device and multiple double-sided threaded pushing devices connected in sequence. The single-sided threaded pushing device includes a horizontally arranged central shaft, the left end of which is connected to a spring. From left to right, a retaining ring, a slider, and a pushing baffle are sequentially mounted on the central shaft. The outer diameter of the slider and the pushing baffle matches the central flow channel. Both sides of the slider have arc-shaped convex surfaces, and the right side of the pushing baffle also has an arc-shaped convex surface. The right end of the central shaft is threaded. The double-sided threaded pushing device is based on the single-sided threaded pushing device and also has threads machined on the left end of the central shaft. The single-sided threaded pushing device and the double-sided threaded pushing device are connected by a flexible base and an asymmetric link. The length of the double-sided threaded pushing device, the flexible base, and the asymmetric link is 8 cm.

4. The pressure relief and permeability enhancement device for achieving adjustable coal seam borehole radius as described in claim 3, characterized in that: The right end of the sleeve housing is provided with two sets of through holes on the left side of the arc-shaped groove. Each set of through holes consists of two holes, which are perpendicular to and connected to the central flow channel. Each through hole is provided with a locking device that matches the through hole. Each locking device includes a locking screw and a spring at the bottom of the locking screw. The bottom of the spring is provided with a trapezoidal limiting device. The lower end of the trapezoidal limiting device is a column, and the upper end is a flat cylinder with a slotted cutter. The long side of the lower end of the trapezoidal limiting device is located at the right end, and the short side of the lower end of the trapezoidal limiting device is located at the left end.

5. The pressure relief and permeability enhancement device for achieving adjustable coal seam borehole radius as described in claim 4, characterized in that: The enlarging assembly includes a flexible tool chain and a tool head assembly located at the end of the flexible tool chain. The flexible tool chain includes multiple asymmetrical links connected end to end. A central block is located between adjacent asymmetrical links. The central block is a cube, and a through hole is provided on each of its four sides. A central block is placed between two asymmetrical links, and the links are fixedly connected by embedding a cross shaft into the through hole.

Images