Pressure relief and permeability increasing device and method for achieving adjustable coal seam reaming radius

Abstract

The invention belongs to the technical field of coal seam gas extraction, chambering, pressure relief and permeability improvement, and particularly relates to a pressure relief and permeability improvement device and method for achieving the adjustable coal seam chambering radius. The pressure relief and permeability improvement device comprises an air compressor and a high-pressure air pipe connected with the air compressor and further comprises a drilling machine, and an output shaft of the drilling machine is rotationally connected with a folding sleeve assembly through a bearing; a drill bit is arranged at the tail end of the folding sleeve assembly, 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 center flow channels and an inner pressure dividing hole pipe are arranged in the sleeve shell, one end of the inner pressure dividing hole pipe is communicated with a high-pressure air pipe, and the other end of the inner pressure dividing hole pipe is communicated with a high-pressure air pipe. A pushing device is arranged in the central flow channel, and a reaming assembly is arranged at the tail end of the pushing device; the arc-shaped notches are communicated with the central flow channel so that the reaming assemblies can stretch out or retract; the pushing device is controlled by air pressure to be located at different positions in the flexible cutter, so that the cutter accurately extends out by a fixed flexible chain length under different air pressures.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal seam gas extraction and hole expansion pressure relief and permeability enhancement, and in particular relates to a pressure relief and permeability enhancement device and method for achieving adjustable coal seam hole expansion radius. Background Art

[0002] As my country's basic energy source and industrial raw material, coal has long provided a strong guarantee for economic and social development and the stable supply of national energy security. Efficient gas extraction is a major requirement for releasing coal production capacity to ensure a safety net energy source and achieving my country's energy security and "dual carbon" strategic goals. In order to solve the problem that the reaming radius of mechanical tools cannot be accurately adjusted during reaming operations, the reaming radius of traditional mechanical tools is fixed during reaming operations. The reaming radius should have a parameter matching relationship with the strength of the coal seam, ground stress, etc., so the optimal gas extraction effect cannot be achieved if the reaming radius is too large or too small. Therefore, maintaining precise control and fixation of the tool length during reaming operations is a necessary prerequisite for efficient coal breaking and efficient gas extraction.

[0003] To overcome the bottleneck in pressure relief and permeability enhancement technology and extract coal seam gas more efficiently, patent number CN202210037215.5 discloses a "device and method for pressure relief and permeability enhancement using pneumatic flexible cutters in soft coal seams." This method utilizes an air compressor to convert air pressure energy into angular kinetic energy for the flexible cutters, driving them to rotate at high speed to break the coal, thus resolving the problems of "hole collapse" and "drill sticking" caused by uneven hole expansion in traditional hole expansion methods. However, this technology cannot precisely control the extension and retraction length of the flexible cable chain, resulting in low hole expansion efficiency for the flexible cutter within the hole, and thus low gas extraction efficiency. To address this issue, a method is proposed that utilizes a locking device in conjunction with a pushing device to precisely control the extension and retraction length of the flexible cutter's flexible cable chain. A retraction and extension mechanism is then used to precisely control the tool's extension length, achieving incremental hole expansion and optimizing the hole expansion radius, thereby achieving coal seam pressure relief, permeability enhancement, and enhanced gas extraction. Summary of the Invention

[0004] The purpose of the present invention is to provide a pressure relief and permeability enhancement device and method for achieving adjustable coal seam hole expansion radius. By controlling the air pressure to push the device at different positions inside the flexible tool, the tool can be accurately extended to a fixed flexible chain length under different air pressures.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A pressure relief and permeability-enhancing device for achieving adjustable coal seam hole expansion radius includes an air compressor, a high-pressure air pipe connected to the air compressor, and a drilling rig. The drilling rig output shaft is rotationally connected to a retracting sleeve assembly through a bearing. A torque sensor and a tachometer are provided on the rotating output shaft of the drilling rig. A drill bit is provided at the end of the retracting sleeve assembly. The retracting sleeve assembly includes a sleeve shell. Two symmetrical arc-shaped slots are provided at the end of the sleeve shell. Two parallel central flow channels and an internal pressure dividing hole tube are provided in the sleeve shell. One end of the internal pressure dividing hole tube is connected to the high-pressure air pipe, and the other end is connected to the central flow channel through two air flow channels. A pushing device is provided in the central flow channel, and a hole expansion assembly is provided at the end of the pushing device. The arc-shaped slot is connected to the central flow channel for the hole expansion assembly to be extended or recovered.

[0006] Furthermore, a threaded cap is provided at the left end of the central flow channel, a threaded pin is provided at the right end of the threaded cap, a tension spring is provided on the threaded pin, the right end of the tension spring is connected to the pushing device, the threaded cap and the central flow channel are threadedly sealed, the length of the internal pressure dividing hole tube is less than the length of the tension spring in its natural state, and this arrangement facilitates the direct application of high-pressure gas to the pushing device.

[0007] Furthermore, the pushing device includes a connected single-sided threaded pushing device and a plurality of double-sided threaded pushing devices 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 a spring, and a retaining spring, a slider and a pushing baffle are sequentially sleeved on the central shaft from left to right. The outer diameters of the slider and the pushing baffle match the central flow channel, the left and right sides of the slider are arc-shaped convex surfaces, the left side of the pushing baffle matches the arc-shaped convex surface, and the right side is also an arc-shaped convex surface, and the right end of the central shaft is threaded; the double-sided threaded pushing device is also threaded at the left end of the central shaft on the basis of the single-sided threaded pushing device; the single-sided threaded pushing device and the double-sided threaded pushing device The devices are connected by a flexible base and an asymmetric chain link. The length of the double-sided threaded pushing device and the flexible base and the asymmetric chain link is 8 cm; the flexible base includes a circular gasket with an external thread, and a U-shaped clamp is provided on the other side of the circular gasket. The asymmetric chain link includes a long axis at the top and a short axis at the bottom. The long axis and the broken axis are connected by an arc block, and the U-shaped clamp is connected to the long axis and the short axis on the same side of the asymmetric chain link through a pin; the retaining spring is clamped on one side of the pushing device to play a limiting role and is connected to the tension spring; the pushing baffle is integrated with the central axis to play a role of sealing air pressure and is connected to the flexible cable chain; the slider is between the retaining spring and the pushing baffle. It can slide on the central axis; the push baffle is combined with the locking device to control the extension and contraction length of the flexible chain, and the 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 tool retraction sleeve from the high-pressure air pipe; the high-pressure gas pushes the push baffle, so that the flexible chain as a whole flows out toward the retraction sleeve notch, and at this time the central flow channel tension spring is in a stressed state; during the movement of the pushing device, when the pushing baffle end is close to the short side of the lower end of the trapezoidal limit device, the pushing baffle will cause the trapezoidal limit device to compress the spring inside the perforation, so that the pushing baffle passes over the trapezoidal limit device, and the trapezoidal limit device is popped out and restored by the spring inside the perforation; at this time, the pushing baffle will be stuck in the trapezoidal limit The long side of the lower end of the device fixes the extension and retraction length of the flexible chain; when the air pressure is increased, the slider on the shaft of the pushing device will be pushed to the retaining spring of the pushing device by the trapezoidal limit device. When the slider does not move at the retaining spring, the trapezoidal limit device will pass over the slider, compress the spring inside the perforation, and after the locking device passes over the slider, the spring inside the perforation is compressed and restored, and the trapezoidal limit device extends; if the air pressure continues to increase, the trapezoidal limit device can successively pass over the subsequent pushing devices, thereby realizing precise control of the extension length of the flexible chain; if the air pressure is reduced, the pushing device can be moved in the opposite direction of the arc-shaped slot, and the trapezoidal limit device is fixed to the push baffle of the pushing device after movement, thereby realizing precise control of the extension and retraction of the flexible chain. Stop the air pressure, the central flow channel tension spring will be restored, pull the flexible chain back to its original position, and the locking device will push the slider to move toward the push baffle. When the slider is tightly fitted with the push baffle, the spring inside the perforation is compressed, and the locking device passes over the slider and the push baffle. After passing over, the spring inside the perforation is restored, and the trapezoidal limit device is restored.

[0008] Furthermore, the right end of the sleeve shell is located on the left side of the arc-shaped slot and is provided with two groups of through holes, the deep part of the through holes is a cylindrical space, and the shallow part is a threaded cylindrical space. There are two in each group of through holes, which are perpendicular to the central flow channel and connected thereto, and a locking device is provided in each through hole. The locking device matches the through hole, and each locking device includes a locking screw, a spring is provided at the bottom of the locking screw, and a trapezoidal limit device is provided at the bottom of the spring. The lower end of the trapezoidal limit device is a cylinder, and the upper end is a flat cylinder with a single-shaped knife. The long side of the lower end cylinder of the trapezoidal limit device is located at the right end, and the short side of the lower end cylinder of the trapezoidal limit device is located at the left end; when in use, the locking device is first placed in the through hole on one side, and then the spring is placed in, and then the locking screw is placed in. The locking screw has a thread, so that it fits tightly with the thread of the through hole. Since the locking screw is fixed, when the trapezoidal limit device is subjected to force, the middle spring is compressed, causing the trapezoidal limit device to move.

[0009] Furthermore, the reaming assembly includes a flexible tool chain and a cutter head assembly located at the end of the flexible tool chain. The flexible tool chain includes a plurality of asymmetric links connected end to end. There is a central block between adjacent asymmetric links. The central block is a cube, and a central block pair is provided with a central block pair through-hole on each of its four sides. The central block is placed between two asymmetric links, and the central block pair through-hole is embedded through a cross axis to fix the connection between the links.

[0010] Furthermore, the cutter head assembly includes a cutter head base and a cutter head portion located on the cutter head base. The cutter head base is provided with a plurality of holes for installing the cutter head portion, and both the cutter head base and the cutter head portion are provided with cutter heads.

[0011] Another object of the present invention is to provide a method for achieving pressure relief and permeability enhancement with precise and adjustable coal seam hole expansion radius, comprising the following steps: S1. Initially, connect the air compressor, high-pressure air pipe, and drilling rig, and retract the reaming assembly into the retractable sleeve assembly. S2. 0.8 MPa of air pressure is applied to the internal pressure-dividing hole tube, initially stretching the tension spring to expand the cutter. The cutter is then stabilized at this length and rotated at a controlled speed of 300 rpm to expand the hole within the coal seam until the entire hole is fully expanded. S3. Increase the air pressure to 1.1 MPa, inputting it into the internal pressure-dividing hole tube. This further stretches the tension spring, increasing the tool extension by 8 cm, the length of one section of the double-threaded pusher, the flexible base, and the asymmetric chain link. This length is then stabilized. The extension of the flexible tool is controlled by controlling the compressor pressure. The tool rotates and expands within the coal seam at a controlled speed of 300 rpm until the entire hole is fully expanded. S4. Increase the air pressure to 1.4 MPa and input it into the internal pressure-dividing hole tube. After the air pressure is turned off, the flexible tool chain retracts into the retracting sleeve. After completing the expansion and permeability enhancement of a coal hole, exit the equipment and prepare for drilling another hole. S5. Repeat steps S2-S4 until all the holes are drilled, expanded, depressurized and permeable.

[0012] This device realizes the process of controlling the adjustable reaming radius: when the trapezoidal limit device is fixed at a certain push baffle, the flexible tool reams the hole with a radius R1. If the air pressure continues to increase to a certain value, the tension spring in the central flow channel stretches, causing several pushing devices and flexible rope chains to move in the direction of the arc-shaped slot. The pushing device that has not crossed the trapezoidal limit device and is closest to the trapezoidal limit device crosses the trapezoidal limit device as the air pressure increases, and the trapezoidal limit device will be fixed at the push baffle that has just crossed the trapezoidal limit device. At this time, the extended length of the flexible rope chain is the sum of the length of the pushing device plus the length of a section of the flexible rope chain at the connection between the pushing devices, totaling 8 cm. At this time, the flexible tool reams the hole with a radius R2. Continue to increase the air pressure to a certain value, the trapezoidal limit device can pass over the next push device and be fixed at the next push baffle. The flexible chain extension length increases by 8cm. Continue to increase the air pressure, the trapezoidal limit device can pass over the subsequent push device and be fixed at the push baffle of the subsequent push device. The flexible chain extension length increases by 8cm each time it passes a push device. At this time, the flexible tool moves with a radius R n The hole is enlarged until the trapezoidal limit device is fixed at the push baffle of the last push device, which can realize the precise extension of the enlarged hole radius; if the enlarged hole radius needs to be precisely retracted, when the trapezoidal limit device is fixed at a certain push baffle (assuming that the push device is a single-sided threaded push device A at this time, and is connected to the push device double-sided threaded push device B and the push device double-sided threaded push device C in the direction of the arc groove), at this time The air pressure value is slightly increased, so that the trapezoidal limit device passes over the slider of this push device A, and then the air pressure is reduced, the tension spring contracts and drives the push device and the flexible chain to move in the opposite direction of the arc groove. The push device previously fixed with the trapezoidal limit device will return to the side of the trapezoidal limit device in the opposite direction of the arc groove. If it needs to be retracted by 8cm, the trapezoidal limit device can pass over the previous push device A, and then pass over the next push device as a whole B. At this time, the trapezoidal limit device is located between the push baffle of the push device B and the slider of the push device C. Slightly increase the air pressure to move the pusher B toward the arc-shaped notch. When the trapezoidal stopper passes over the push baffle of the pusher B, the air pressure can be turned off to fix it there. At this point, the flexible chain is retracted to 8 cm, which allows for precise shrinkage of the hole radius.

[0013] The advantages of the present invention are: 1. The present invention proposes a pressure relief and permeability enhancement device and method for achieving precise and adjustable coal seam hole expansion radius, with the characteristics of precise control of the extension length of the flexible tool, stable extension length, and automatic retraction; 2. The locking device invented works together with the pushing device to push the baffle to be fixed at the trapezoidal limit device, and the flexible tool's telescopic length can be precisely controlled and the extended length is stable; 3. The multi-stage pushing device consisting of a single-side threaded pushing device and a double-side threaded pushing device can more accurately control the extension length of the flexible tool. In addition, the slider of the pushing device cooperates with the trapezoidal limit device to realize the feature of automatic retraction of the flexible tool after extension; 4. The connection between the links of the flexible cable chain of the flexible tool is through the central block and the cross axis, which not only maintains the flexibility of the flexible cable chain, but also makes the links of the flexible cable chain firm; 5. The hemispherical cutter head at the end of the flexible tool and flexible cable chain enables efficient coal breaking and gas extraction during the integrated drilling and expansion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0015] Figure 2 It is a structural schematic diagram of the sleeve housing of the present invention.

[0016] Figure 3 It is a schematic structural diagram of the retractable sleeve assembly in the present invention.

[0017] Figure 4 It is a schematic diagram of the high-pressure gas flow structure inside the flexible tool of the present invention.

[0018] Figure 5 Schematic diagram of the locking device structure of the present invention, wherein a is a schematic diagram of the overall structure; b is a schematic diagram of the limit device structure; c is a schematic diagram of the locking screw structure.

[0019] Figure 6 It is a structural schematic diagram of the pushing device in the present invention, wherein a is a structural schematic diagram of a single-sided threaded pushing device; b is a structural schematic diagram of a double-sided threaded pushing device; c is a structural schematic diagram of a pushing baffle; d is a structural schematic diagram of a slider; and e is a structural schematic diagram of a retaining spring.

[0020] Figure 7 It is a diagram of the interaction process between the pushing device and the trapezoidal limiting device.

[0021] Figure 8 It is a flow chart of the interaction between the pushing device and the trapezoidal limiting device.

[0022] Figure 9 Schematic diagram of the overall structure of the flexible tool chain.

[0023] Figure 10 yes Figure 9 A partial enlarged view, where a is a schematic diagram of the flexible base structure; b is a schematic diagram of the chain link structure.

[0024] Figure 11 It is a schematic diagram of the structure of the central block and the cross shaft between the chain links; a is a schematic diagram of the structure of the central block; b is a schematic diagram of the structure of the cross shaft.

[0025] Figure 12 Schematic diagram of the cutter head structure of the present invention; wherein, a is a schematic diagram of the overall structure of the cutter head; b is a schematic diagram of the cutter head structure; c is a schematic diagram of the cutter head base structure.

[0026] In the figure: 1. air compressor; 2. high-pressure air pipe; 3. drilling rig; 4. drilling rig output shaft; 5. retracting sleeve assembly; 6. drill bit; 7. center flow channel; 8. internal pressure-dividing hole tube; 9. arc-shaped notch; 10. through hole; 11. air flow channel; 12. tension spring; 13. threaded shaft pin; 14. threaded cap; 20. single-sided threaded pushing device; 21. retaining spring; 22. slider; 23. pushing baffle; 30. locking device; 31. trapezoidal limit device; 32. spring; 33. locking screw; 40. center block; 41. through hole of center block; 42. cross shaft; 50. cutter head; 51. cutter head head; 52. cutter head base; 61. flexible base; 62. chain link; 201. double-sided threaded pushing device. DETAILED DESCRIPTION

[0027] like Figure 1-12As shown, a pressure relief and permeability-enhancing device for achieving adjustable coal seam hole expansion radius includes an air compressor 1, a high-pressure air pipe 2 connected to the air compressor, and a drilling rig 3. The drilling rig output shaft 4 is rotationally connected to the retracting sleeve assembly 5 through a bearing. A torque sensor and a tachometer are provided on the rotating output shaft of the drilling rig. A drill bit 6 is provided at the end of the retracting sleeve assembly. The retracting sleeve assembly includes a sleeve shell. Two symmetrical arc-shaped slots 9 are provided at the end of the sleeve shell. Two parallel central flow channels 7 and an internal pressure dividing hole tube 8 are provided in the sleeve shell. One end of the internal pressure dividing hole tube 8 is connected to the high-pressure air pipe 2, and the other end is connected to the central flow channel through two air flow channels. A pushing device is provided in the central flow channel, and a hole expansion assembly is provided at the end of the pushing device; the arc-shaped slot is connected to the central flow channel for the hole expansion assembly to be extended or recovered.The left end of the central flow channel is provided with a threaded cap 14, the right end of the threaded cap is provided with a threaded pin 13, a tension spring 12 is provided on the threaded pin, the right end of the tension spring is connected to the pushing device, the threaded cap and the central flow channel are threadedly sealed, the length of the internal 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 comprises a connected single-sided threaded pushing device 20 and a plurality of double-sided threaded pushing devices 201 connected in sequence, the single-sided threaded pushing device comprises a horizontally arranged central shaft, the left end of the central shaft is connected to the spring, and the central shaft is sequentially sleeved with a retaining spring 21, a slider 22 and a pushing device from left to right. The 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, and the right end of the central shaft is threaded; the double-sided threaded pushing device is also threaded at the left end of the central shaft on the basis of the single-sided threaded pushing device; the single-sided threaded pushing device and the double-sided threaded pushing device are connected by a flexible base 61 and an asymmetric chain link 62, and the length of the double-sided threaded pushing device and the flexible base and the asymmetric chain link is 8 cm; the retaining spring is clamped on one side of the pushing device to play a limiting role and is connected to the tension spring; the pushing baffle is integrated with the central shaft to seal the air pressure and is connected to the flexible cable The chain is connected; the slider is between the retaining spring and the pushing baffle and can slide on the central axis; the pushing baffle is combined with the locking device to control the extension and contraction length of the flexible cable chain, and the 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 tool retraction sleeve from the high-pressure air pipe; the high-pressure gas pushes the pushing baffle, causing the flexible cable chain to flow out toward the retraction sleeve notch as a whole, and at this time the tension spring of the central flow channel is in a stressed state; during the movement of the pushing device, when the pushing baffle end is close to the short side of the lower end of the trapezoidal limit device, the pushing baffle will cause the trapezoidal limit device to compress the spring inside the perforation, so that the pushing baffle passes the trapezoidal limit device, and the trapezoidal limit device is popped out and restored by the spring inside the perforation; at this time, the pushing The baffle will be stuck on the long side of the lower end of the trapezoidal limit device, so that the extension and contraction length of the flexible chain is fixed; when the air pressure is increased, the slider on the shaft of the pushing device will be pushed to the retaining spring of the pushing device by the trapezoidal limit device. When the slider does not move at the retaining spring, the trapezoidal limit device will pass over the slider, compress the spring inside the perforation, and after the locking device passes over the slider, the spring inside the perforation is compressed and restored, and the trapezoidal limit device extends; if the air pressure continues to increase, the trapezoidal limit device can pass over the subsequent pushing devices in succession, so as to realize precise control of the extension length of the flexible chain; if the air pressure is reduced, the pushing device can be moved in the opposite direction of the arc-shaped slot, and the trapezoidal limit device is fixed to the push baffle of the moving pushing device, so as to realize precise control of the extension and contraction of the flexible chain.Stop the air pressure, the central flow channel tension spring will be restored, pull the flexible chain back to its original position, and the locking device will push the slider to move toward the push baffle. When the slider is tightly fitted with the push baffle, the spring inside the perforation is compressed, and the locking device passes over the slider and the push baffle. After passing over, the spring inside the perforation is restored, and the trapezoidal limit device is restored. The right end of the sleeve housing is located on the left side of the arc-shaped notch and is provided with two groups of through holes 10. The deep part of the through hole is a cylindrical space, and the shallow part is a threaded cylindrical space. There are two through holes in each group, which are respectively perpendicular to the central flow channel and connected thereto. A locking device 30 is provided in each through hole. The locking device matches the through hole, and each locking device includes a locking screw 33. A spring 32 is provided at the bottom of the locking screw. A trapezoidal limiting device 31 is provided at the bottom of the spring. The lower end of the trapezoidal limiting device is a cylinder, and the upper end is a flat cylinder with a one-word flower knife. The long side of the cylinder at the lower end of the trapezoidal limiting device is located at the right end, and the short side of the cylinder at the lower end of the trapezoidal limiting device is located at the left end. When in use, the locking device is first placed in the through hole on one side, and then the spring is placed in, and then the locking screw is placed in. The locking screw has a thread, so that it fits tightly with the through hole thread. 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 reaming assembly includes a flexible tool chain and a cutter head assembly located at the end of the flexible tool chain. The flexible tool chain includes a plurality of asymmetric links 62 connected end to end. There is a central block 40 between adjacent asymmetric links. The central block is a cube, and a central block pair through-hole 41 is provided on each of its four sides. The central block is placed between two asymmetric links, and the central block pair through-hole is embedded through a cross shaft 42 to fix the chain links. The cutter head assembly includes a cutter head base 52 and a cutter head 51 located on the cutter head base. The cutter head base is provided with a plurality of holes for installing the cutter head. The cutter head base and the cutter head are both provided with a plurality of evenly arranged carbide cutter heads 50.

[0028] Another object of the present invention is to provide a pressure relief and permeability enhancement device and method for achieving precise and adjustable coal seam hole expansion radius, comprising the following steps: S1. Initially, connect the air compressor, high-pressure air pipe, and drilling rig, and retract the reaming assembly into the retractable sleeve assembly. S2. 0.8 MPa of air pressure is applied to the internal pressure-dividing hole tube, initially stretching the tension spring to expand the cutter. The cutter is then stabilized at this length and rotated at a controlled speed of 300 rpm to expand the hole within the coal seam until the entire hole is fully expanded. S3. Increase the air pressure to 1.1 MPa, inputting it into the internal pressure-dividing hole tube. This further stretches the tension spring, increasing the tool extension by 8 cm, the length of one section of the double-threaded pusher, the flexible base, and the asymmetric chain link. This length is then stabilized. The extension of the flexible tool is controlled by controlling the compressor pressure. The tool rotates and expands within the coal seam at a controlled speed of 300 rpm until the entire hole is fully expanded. S4. Increase the air pressure to 1.4 MPa and input it into the internal pressure-dividing hole tube. After the air pressure is turned off, the flexible tool chain retracts into the retracting sleeve. After completing the expansion and permeability enhancement of a coal hole, exit the equipment and prepare for drilling another hole. S5. Repeat steps S2-S4 until all the holes are drilled, expanded, depressurized and permeable.

Claims

1. A pressure relief and permeability enhancement device for achieving adjustable coal seam hole expansion radius, characterized by: The invention comprises an air compressor, a high-pressure air pipe connected to the air compressor, and a drilling rig. The output shaft of the drilling rig is rotatably connected to the retractable sleeve assembly through a bearing. A drill bit is provided at the end of the retractable sleeve assembly. The retractable sleeve assembly comprises a sleeve shell. Two symmetrical arc-shaped notches are provided at the end of the sleeve shell. Two parallel central flow channels and an internal pressure dividing hole tube are provided in the sleeve shell. One end of the internal pressure dividing hole tube is connected to the high-pressure air pipe, and the other end is connected to the central flow channel through two air flow channels. A pushing device is provided in the central flow channel. A reaming assembly is provided at the end; the arc-shaped slot is connected to the central flow channel for the reaming assembly to extend or retract; the reaming assembly includes a flexible tool chain and a cutter head assembly located at the end of the flexible tool chain, the flexible tool chain includes a plurality of asymmetric links connected end to end, and a central block is between adjacent asymmetric links. The central block is a cube, and a central block pair of through holes is provided on each of the four sides of the central block. The central block is placed between two asymmetric links, and the central block pair of through holes is embedded in the cross axis to fix the links.

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

3. The pressure relief and permeability-enhancing device for achieving adjustable coal seam hole expansion radius according to claim 1, characterized in that: The pushing device includes a connected single-sided threaded pushing device and a plurality of double-sided threaded pushing devices 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 a spring, and a retaining spring, a slider and a pushing baffle are sequentially sleeved on the central shaft from left to right. The outer diameters of the slider and the pushing baffle match the central flow channel, the left and right sides of the slider are both arc-shaped convex surfaces, the left side of the pushing baffle matches the arc-shaped convex surface, and the right side is also an arc-shaped convex surface, and the right end of the central shaft is threaded; the double-sided threaded pushing device is also threaded at the left end of the central shaft on the basis of the single-sided threaded pushing device; the single-sided threaded pushing device and the double-sided threaded pushing device are connected by a flexible base and an asymmetric chain link, and the length of the double-sided threaded pushing device, the flexible base and the asymmetric chain link is 8 cm.

4. The pressure relief and permeability enhancement device for achieving adjustable coal seam hole expansion radius according to claim 1, characterized in that: The right end of the sleeve shell is located on the left side of the arc-shaped groove and is provided with two groups of through holes, each group of through holes is two, respectively perpendicular to the central flow channel and connected thereto, and a locking device is provided in each through hole, and the locking device matches the through hole, and each locking device includes a locking screw, the locking screw is threaded on the outside, a regular hexagonal countersunk hole is provided on the top, and a spring accommodating chamber is provided at the bottom of the locking screw, and a trapezoidal limiting device is provided at the bottom of the spring, the lower end of the trapezoidal limiting device is a cylinder, and the upper end is a flat cylinder with a straight-shaped flower knife, the long side of the lower end cylinder of the trapezoidal limiting device is located at the right end, and the short side of the lower end cylinder of the trapezoidal limiting device is located at the left end.

5. The pressure relief and permeability enhancement device for achieving adjustable coal seam hole expansion radius according to claim 3, characterized in that: The flexible base includes a circular gasket with an external thread, and a U-shaped clamp is provided on the other side of the circular gasket. The asymmetric chain link includes a long axis located at the upper part and a short axis located at the lower part. The long axis and the broken axis are connected by an arc block. The U-shaped clamp is connected to the long axis and the short axis on the same side of the asymmetric chain link through a pin shaft.

6. The pressure relief and permeability enhancement device for achieving adjustable coal seam hole expansion radius according to claim 1, characterized in that: The cutter head assembly includes a cutter head base and a cutter head portion located on the cutter head base, and cutter heads are provided on both the cutter head base and the cutter head portion.

7. The pressure relief antireflection method of the device according to claim 1, characterized in that: The following steps are involved: S1. Initially, connect the air compressor, high-pressure air pipe, and drilling rig, and retract the reaming assembly into the retractable sleeve assembly. S2. 0.8 MPa of air pressure is applied to the internal pressure-dividing hole tube, initially stretching the tension spring to expand the cutter. The cutter is then stabilized at this length and rotated at a controlled speed of 300 rpm to expand the hole within the coal seam until the entire hole is fully expanded. S3. Increase the air pressure to 1.1 MPa, inputting it into the internal pressure-dividing hole tube. This further stretches the tension spring, increasing the tool extension by 8 cm, the length of one section of the double-threaded pusher, the flexible base, and the asymmetric chain link. This length is then stabilized. The extension of the flexible tool is controlled by controlling the compressor pressure. The tool rotates and expands within the coal seam at a controlled speed of 300 rpm until the entire hole is fully expanded. S4. Increase the air pressure to 1.4 MPa and input it into the internal pressure-dividing hole tube. After the air pressure is turned off, the flexible tool chain retracts into the retracting sleeve. After completing the expansion and permeability enhancement of a coal hole, exit the equipment and prepare for drilling another hole. S5. Repeat steps S2-S4 until all the holes are drilled, expanded, depressurized and permeable.

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