Coal seam reaming device and reaming method

Abstract

The invention discloses a coal seam reaming device and method. The coal seam reaming device comprises a drill rod, a drilling unit and a reaming unit. The reaming unit comprises a cutter wing assembly, a hydraulic adjusting assembly and a protection mechanism. The cutter wing assembly can be unfolded from the containing position to the reaming position, the hydraulic adjusting assembly responds to fluid pressure to drive the cutter wings to move, fluid is laterally jetted in the unfolding process through the flow dividing pipe and the second jet orifice, reaming is assisted, and friction resistance is reduced. The protection mechanism isolates the meshing area of the driving teeth and the rack through multiple layers of baffles and a fixing base, coal particles are prevented from entering, and the jamming risk is reduced. The reaming method comprises drilling, reaming and withdrawing stages, the blade wings are controlled to be unfolded and reset by adjusting fluid pressure, and fluid is synchronously sprayed to wash the hole wall. The device realizes flow and expansion angle matching through the divergent water outlet, and the protection mechanism dynamically isolates to ensure reliability. The reaming efficiency is remarkably improved, the operation time is shortened, and the failure rate is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal seam mining, in particular to a device and method for drilling and reaming of coal seam, especially a reaming device and method for coal seam. BACKGROUND

[0002] In the modern mining process of coal mine, drilling operation is an indispensable key link. In order to improve the extraction efficiency of coal bed methane (gas), implement hydraulic fracturing to increase permeability, conduct hydrogeological exploration or install underground equipment, it is often necessary to carry out secondary reaming on the basis of the initial drilling to form a larger diameter stable hole. Mechanical reaming devices, especially the cutter wing type reamer integrated on the drill rod, are widely used due to their compact structure and convenient operation.

[0003] The existing cutter wing type reaming device usually adopts hydraulic or mechanical method to drive the cutter wing housed in the drill rod body to expand, and the rotation of the drill rod realizes the cutting of the hole wall to expand the hole diameter. The working principle is generally as follows: after drilling to the predetermined depth, the high pressure of the pump into the drill rod is increased to drive a piston-rack mechanism to move, the rack in turn engages with the gear on the cutter wing base to make the cutter wing rotate and expand. After completing the reaming, the water pressure is reduced, and the cutter wing is retracted under the action of the reset spring or the reverse hydraulic pressure.

[0004] However, in actual underground operation, especially in coal seams with complex geological conditions, soft coal or gangue, such devices expose several technical bottlenecks that are difficult to overcome. The first problem is the jamming failure of the driving mechanism. A large amount of coal powder, debris and mud will be produced during the drilling and reaming of the coal seam. These fine particles can easily invade the movable joints of the cutter wing expansion, especially the internal transmission mechanism of the precise meshing of the gear and the rack. Once the particles accumulate and embed, the meshing resistance will increase dramatically, which may cause the cutter wing to fail to expand or retract smoothly and completely, affecting the continuity of the reaming operation and the accuracy of the reaming diameter; or even cause the gear and the rack to be completely jammed, making the entire drilling tool unable to be taken out of the hole, causing serious underground accidents and huge economic losses.

[0005] Secondly, the low reaming efficiency is another major problem. The traditional reaming cutter wing mainly relies on the hardness and sharpness of the blade to mechanically scrape the coal and rock body. When the hardness of the coal seam is uneven or hard layers are encountered, the load of mechanical cutting will increase dramatically, which not only reduces the reaming speed, but also aggravates the wear of the cutter wing and shortens its service life. Although high pressure water flow exists in the system, its main role is realized after the cutter wing is fully expanded, which is used for cooling and debris removal. During the expansion of the cutter wing, there is a lack of effective hydraulic assistance, which limits the coal breaking capacity of the whole process.

[0006] To solve the problem of jamming, some designs attempt to increase the sealing element, but the harsh environment of high pressure and high abrasion in the well makes the flexible sealing element such as rubber easily damaged, with a short service life, and unable to provide long-term reliable protection. In order to improve efficiency, some hydraulic slotting techniques use the power of high-pressure water jet, but the device structure is often separated from the mechanical reamer, requiring step-by-step operation, and the process is complicated, and the mechanical and hydraulic coal breaking cannot be effectively coordinated.

[0007] Therefore, it is a technical problem to be solved in the field to develop a new coal seam reaming device that can fundamentally solve the problem of jamming of the driving mechanism and can coordinate mechanical cutting and hydraulic jetting to improve reaming efficiency. SUMMARY

[0008] Therefore, the purpose of the present application is to solve the technical problems of the reaming cutter wing driving mechanism being easily jammed by coal debris and low reaming efficiency, and to provide a coal seam reaming device and a reaming method. By setting a protection mechanism to physically isolate the driving mechanism of the cutter wing assembly, the entry of coal particles is prevented, and a hydraulic adjusting assembly is used to synchronously inject fluid to assist reaming during the expansion and retraction of the cutter wing.

[0009] To achieve the above purpose, the present application provides the following technical solutions:

[0010] A coal seam reaming device, comprising:

[0011] a drill rod;

[0012] a drilling unit installed at one end of the drill rod;

[0013] a reaming unit provided on the drill rod, the reaming unit comprising at least one cutter wing assembly expandable from a storage position to a reaming position, a hydraulic adjusting assembly for driving the cutter wing assembly to move between the storage position and the reaming position in response to changes in fluid pressure, and a protection mechanism for physically isolating the driving mechanism of the cutter wing assembly from the external coal seam environment.

[0014] Further, the hydraulic adjusting assembly is also used to inject fluid from the reaming unit to flush the working area of the cutter wing assembly during the expansion or retraction of the cutter wing assembly.

[0015] Further, the cutter wing assembly comprises a rotating wheel and a cutter wing body fixed to the rotating wheel; the driving mechanism comprises a driving tooth provided on the rotating wheel and a rack engaged with the driving tooth.

[0016] Further, the protection mechanism surrounds the engagement area of the driving tooth and the rack to block the entry of external particles; the protection mechanism comprises:

[0017] At least one first baffle, rotating with the runner;

[0018] A second baffle, fixedly arranged and in sliding contact with the outer arc surface of the runner;

[0019] A fixed seat, in sliding cooperation with the first baffle, together forming a closed or semi-closed isolation of the engagement area.

[0020] Further, one side of the fixed seat is provided with an arc surface matching the arc of the first baffle; the second baffle is in the same horizontal plane as the axis of the runner and is in sliding connection with the outer side of the runner.

[0021] Further, the hydraulic adjusting assembly comprises:

[0022] A piston block, axially movable under the action of fluid pressure;

[0023] A sliding block, in linkage with the piston block and bearing the rack.

[0024] Further, the reaming unit is provided with a straight-through pipe and a shunt pipe; the piston block is sleeved on the outer side of the straight-through pipe; the sliding block is sleeved on the outer side of the shunt pipe.

[0025] Further, the straight-through pipe is used to guide fluid to the drill bit of the drilling unit; the shunt pipe is used to guide fluid to the second jet port of the working area of the blade assembly.

[0026] Further, the axial movement of the piston block controls the on-off and flow rate of fluid entering the shunt pipe.

[0027] Further, the piston block is provided with a shunt hole, and the inner wall of the reaming unit is provided with a water outlet in communication with the shunt pipe; when the piston block moves, the overlapping area of the shunt hole and the water outlet changes, thereby adjusting the flow rate of fluid flowing to the shunt pipe.

[0028] Further, the opening shape of the water outlet gradually expands along the moving direction of the piston block, so that during the unfolding of the blade assembly, the flow rate of fluid flowing to the shunt pipe increases with the increase of the unfolding angle.

[0029] Further, the hydraulic adjusting assembly further comprises a return spring sleeved between the piston block and the inner wall of the reaming unit, for driving the piston block to return when the fluid pressure decreases.

[0030] Further, the reaming unit comprises a reaming block, the reaming block is provided with a containing groove for accommodating the blade assembly, and a converging groove for accommodating the hydraulic adjusting assembly.

[0031] Further, the drilling unit comprises a drill bit, and a first jetting port is arranged on the drill bit and communicates with the straight-through pipe, so that the drill bit can be cooled and the drill bit can be used for cutting.

[0032] Further, the cutter wing assembly is symmetrically arranged in two parts, which are arranged on opposite sides of the reaming unit.

[0033] Further, a limiting ring is arranged outside the straight-through pipe to limit the axial movement range of the piston block.

[0034] Further, a through slot is arranged inside the sliding block to accommodate the shunt pipe, so that the sliding block can stably slide along the shunt pipe.

[0035] A coal seam reaming method using the coal seam reaming device, comprising the following steps:

[0036] Drilling stage: injecting fluid with a first pressure value into the device, so that the fluid is mainly sprayed through the drilling unit to perform drilling operation, and at this time, the cutter wing assembly is in the storage position;

[0037] Reaming stage: the fluid pressure is increased to a second pressure value, the hydraulic adjusting assembly is driven to act, the cutter wing assembly is expanded to the reaming position, and part of the fluid is sprayed through the reaming unit to perform reaming and flushing operation.

[0038] Further, the method further comprises a recovery stage:

[0039] The fluid pressure is reduced, the hydraulic adjusting assembly is reversely moved under the action of the reset mechanism, the cutter wing assembly is recovered to the storage position, and during the recovery process, the fluid is continuously or intermittently sprayed from the reaming unit.

[0040] The present application has the following advantages:

[0041] The present application uses the drill bit of the drilling unit to initially drill the coal seam, and the drill bit carries the reaming unit into the hole. At this stage, the hydraulic adjusting assembly guides the fluid to the drill bit to achieve accelerated cooling and slag removal, and the protection mechanism continuously isolates the driving mechanism (such as the meshing area of the driving teeth and the rack) of the cutter wing assembly to prevent coal particles from entering. This effectively prevents jamming and ensures smooth expansion of the cutter wing body, improving the reliability and continuity of the device. Compared with the prior art, the protection mechanism uses a combination of multiple baffles and fixed seats to form a closed or semi-closed isolation area, dynamically adapts to the movement of the runner, blocks the invasion of particles, and estimates that the reaming failure rate can be reduced to less than 5%.

[0042] In the reaming stage, the present application pushes the hydraulic adjusting assembly forward by increasing the fluid pressure, drives the cutter body to gradually expand, and realizes continuous lateral injection during the expansion process through the shunt pipe and the second injection port. The synchronous fluid impact softens the coal wall, reduces the mechanical friction resistance, timely discharges the slag, shortens the overall reaming time by 30%-50%, reduces the cutter wear, and improves the device life. Compared with the traditional device that only injects fluid after complete expansion, the water outlet of the present application adopts a gradually expanding design to ensure that the fluid intensity matches the expansion angle, provides assistance from the early expansion stage, and significantly improves the efficiency.

[0043] The present application optimizes the fluid path: the straight pipe ensures drill bit cooling, the shunt pipe and the water outlet realize lateral shunting, the gradual connection of the shunt hole and the water outlet avoids pressure sudden change, and ensures smooth transition. The protection mechanism combines with continuous injection during the reset process to prevent particle accumulation, ensure the smooth retraction of the cutter, avoid device jamming, enhance the adaptability in complex coal seams (such as high ash content or soft layer), and is suitable for deep well operation. The hydraulic adjusting assembly integrates angle control and injection function, easy to operate, no need for additional auxiliary equipment, and reduces the cost. The isolation effect of the protection mechanism improves the safety performance and reduces the risk of human intervention. Efficient fluid utilization reduces water resource waste and slag discharge optimization reduces dust pollution. The present application is superior to the prior art in reliability, efficiency and economy, and provides an innovative solution for coal seam mining.

[0044] Other advantages, objects, and features of the present application will be apparent to those skilled in the art from the following specification, and will be learned from the practice of the present application. The objects and other advantages of the present application can be achieved and obtained by the following specification. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to make the purpose, technical scheme and advantages of the present application more clear, the preferred detailed description of the present application will be combined with the drawings as follows, in which:

[0046] Figure 1 The figure is a schematic diagram of the overall structure of the present application.

[0047] Figure 2 The figure is a schematic diagram of the internal structure of the reaming block of the present application.

[0048] Figure 3 The figure is a schematic diagram of the protection mechanism structure of the present application.

[0049] Figure 4 The figure is a schematic diagram of the cutter body opening process of the present application.

[0050] Figure 5 The figure is a schematic diagram of the cooperation between the runner and the slider of the present application.

[0051] Figure 6 Figure for cooperation relationship between straight-through pipe and piston block of the present application.

[0052] Figure 7 Figure for cooperation relationship between first baffle and second baffle of the present application.

[0053] Figure 8 Figure for structure of blade wing assembly of the present application.

[0054] Figure 9 Figure for cooperation relationship between water outlet and switching hole of the present application.

[0055] Figure 10 Figure for step-by-step connection between shunt hole and water outlet of the present application.

[0056] Figure 11 Figure for cooperation relationship between shunt pipe and second jetting port of the present application.

[0057] Fig. 1 is a schematic view of the drilling unit; Fig. 2 is a schematic view of the reaming unit; Fig. 3 is a schematic view of the hydraulic adjusting assembly; Fig. 4 is a schematic view of the blade wing assembly; Fig. 5 is a schematic view of the straight-through pipe and the piston block; Fig. 6 is a schematic view of the first baffle and the second baffle; Fig. 7 is a schematic view of the water outlet and the switching hole; Fig. 8 is a schematic view of the shunt hole and the water outlet; Fig. 9 is a schematic view of the shunt pipe and the second jetting port. DETAILED DESCRIPTION

[0058] The present application is described in detail below with specific reference being made to certain embodiments. Those skilled in the art will readily understand other advantages and benefits of the present application from the following description. The present application may be embodied in other different embodiments and applied to other different situations without departing from the spirit and essential characteristics of the present application. It should be noted that the drawings provided in the following examples only schematically illustrate the basic concept of the present application, and the following examples and features in the examples can be combined with each other without conflict.

[0059] The drawings are only used for exemplary illustration, and the representation is only a schematic diagram, not a physical diagram, and cannot be understood as a limitation on the present application; in order to better illustrate the embodiments of the present application, some components of the drawings may be omitted, enlarged or reduced, and do not represent the actual product size; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0060] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the positional relationship described in the drawings is only used for exemplary illustration, and cannot be understood as a limitation on the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0061] The present application provides a coal seam reaming device and a reaming method, as shown in Figure 1 The device includes a drill rod 11, a drilling unit 1 and a reaming unit 2. The drilling unit 1 is installed at one end of the drill rod 11, and the reaming unit 2 is arranged on the drill rod 11. The reaming unit 2 includes at least one blade assembly 21, a hydraulic adjusting assembly 22 and a protection mechanism 215. The blade assembly 21 can be unfolded from the storage position to the reaming position, the hydraulic adjusting assembly 22 drives the blade assembly 21 to move in response to the change of fluid pressure, and the protection mechanism 215 physically isolates the driving mechanism of the blade assembly 21 from the external coal seam environment.

[0062] As shown in Figures 1-2 The drilling unit 1 includes a drill bit 13 and a joint 12. The joint 12 is connected to the end of the drill rod 11 opposite the drill bit 13, and is used to install the drill rod 11 on the driving mechanism. The drill bit 13 is provided with a first jet port 131, which communicates with the straight-through pipe 211, and is used for cooling and chip removal during drilling. The reaming unit 2 includes a reaming block 210, which is provided with a receiving groove 2101 for accommodating the blade assembly 21 and a converging groove 2104 for accommodating the hydraulic adjusting assembly 22.

[0063] As shown in Figures 3-5As shown in Figures 7-8, the blade assembly 21 includes a rotating wheel 216, a blade body 214, a hinge shaft 213, a straight pipe 211, a diverter pipe 212, and a protective mechanism 215. The blade body 214 is fixed to the rotating wheel 216, which is rotatably sleeved on the outside of the hinge shaft 213. The hinge shaft 213 is fixed in the receiving groove 2101 near the hydraulic adjustment assembly 22. The rotating wheel 216 has a drive tooth 2161 at its lower part, with an arc-shaped outer surface. The drive mechanism includes the drive tooth 2161 and a rack 2222 that meshes with the drive tooth 2161. The protective mechanism 215 surrounds the meshing area of ​​the drive tooth 2161 and the rack 2222, blocking external particles from entering, and includes a first baffle 2151, a second baffle 2152, and a fixing seat 2153. The first baffle 2151 is fixed to both ends of the outer side of the rotating wheel 216 and rotates with the rotating wheel 216; the second baffle 2152 is fixed to one end of the receiving groove 2101, located between the two sets of first baffles 2151, and slides in contact with the outer arc surface of the rotating wheel 216; the fixing seat 2153 is fixed to one end of the receiving groove 2101, located at both ends of the second baffle 2152, and slides in cooperation with the first baffle 2151 to form a closed or semi-closed isolation. One side of the fixing seat 2153 is provided with an arc surface that matches the curvature of the first baffle 2151, and the second baffle 2152 is on the same horizontal plane as the axis of the hinge shaft 213 and slides in connection with the outer side of the rotating wheel 216.

[0064] like Figures 6-11 As shown, the hydraulic regulating assembly 22 includes a piston block 221, a slider 222, a push sleeve 2212, and a return spring 223. The piston block 221 moves axially under fluid pressure and is fitted onto the outside of the straight pipe 211. The slider 222 is linked to the piston block 221, carries a rack 2222, and is slidably fitted onto the outside of the diverter pipe 212. It has an internal through groove 2221 to accommodate the diverter pipe 212, ensuring stable sliding. The push sleeve 2212 is fitted onto the outside of the straight pipe 211, connecting the piston block 221 and the slider 222. The return spring 223 is fitted onto the outside of the push sleeve 2212 and located within the converging groove 2104, used to drive the piston block 221 to return to its original position when the fluid pressure decreases. A limiting ring 2111 is provided on the outside of the straight pipe 211 to limit the movement range of the piston block 221. The straight pipe 211 guides the fluid to the drill bit 13, and the diverter pipe 212 guides the fluid to the second injection port 2121 in the working area of ​​the blade assembly 21. The axial movement of the piston block 221 controls the flow and flow rate of the fluid entering the diverter pipe 212. The piston block 221 is provided with a diverter hole 2211, which has an L-shaped structure to optimize the fluid path. The inner wall of the reamer 210 is provided with an outlet 2103 that communicates with the diverter pipe 212. When the piston block 221 moves, the overlapping area of ​​the diverter hole 2211 and the outlet 2103 changes, thus regulating the flow rate. The outlet 2103 gradually expands along the moving direction of the piston block 221, so that the flow rate increases with the unfolding angle when the blade assembly 21 unfolds.

[0065] The hole enlargement method includes the following steps:

[0066] Drilling stage: the driving mechanism rotates the reamer block 210 and the drill bit 13 through the drill pipe 11, and the blade assembly 21 is in the storage position. Fluid at a first pressure value is injected, and the fluid is sprayed out of the first spray port 131 through the water inlet pipe 121, the drill pipe 11, the converging groove 2104, and the straight pipe 211, to cool the drill bit 13 and discharge coal debris. The shunt hole 2211 is misaligned with the water outlet 2103, and the fluid does not enter the shunt pipe 212. The protection mechanism 215 forms an isolation area through the first baffle 2151, the second baffle 2152, and the fixed seat 2153, to prevent the debris from entering the meshing area of the driving tooth 2161 and the rack 2222.

[0067] Reaming stage: the drill bit 13 stops advancing, the fluid pressure is increased to a second pressure value, the piston block 221 is moved along the converging groove 2104, and the shunt hole 2211 is gradually connected with the water outlet 2103. The piston block 221 compresses the return spring 223, pushes the push sleeve 2212 and the sliding block 222 along the shunt pipe 212, the sliding block 222 cooperates with the driving tooth 2161 through the rack 2222, drives the rotating wheel 216 to rotate around the hinge shaft 213, and the blade body 214 is gradually unfolded. The fluid is sprayed out of the second spray port 2121 through the shunt hole 2211, the water outlet 2103, the adapter hole 2102, and the shunt pipe 212, to flush the hole wall and assist reaming. The gradually expanding design of the water outlet 2103 ensures that the flow rate increases with the increase of the unfolding angle, and provides assistance at the initial stage to reduce frictional resistance.

[0068] Retracting stage: the fluid pressure is reduced, the return spring 223 pushes the piston block 221 to reset, and the sliding block 222 and the blade body 214 are returned to the containing groove 2101. The shunt hole 2211 is gradually misaligned with the water outlet 2103, the second spray port 2121 is continuously or intermittently sprayed, the debris is prevented from accumulating, and the blade is smoothly retracted.

[0069] The present application solves the problem of jamming by isolating the driving mechanism through the protection mechanism 215, and solves the problem of lack of hydraulic assistance at the initial stage of unfolding through the synchronous spraying of the hydraulic pressure adjusting assembly 22. The device structure is optimized, the operation is simple, it is suitable for complex coal seams, and the efficiency and reliability are improved.

[0070] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A coal seam borehole enlargement device, characterized in that, include: Drill pipe; A drilling unit is installed at one end of the drill rod; A reaming unit is disposed on the drill rod. The reaming unit includes at least one blade assembly that can be deployed from a receiving position to a reaming position, a hydraulic adjustment component for driving the blade assembly to move between the receiving position and the reaming position in response to changes in fluid pressure, and a protective mechanism for physically isolating the drive mechanism of the blade assembly from the external coal seam environment.

2. The coal seam borehole enlargement device according to claim 1, characterized in that, The hydraulic adjustment component is also used to spray fluid from the orifice expansion unit to flush the working area of ​​the blade assembly during the process of driving the blade assembly to unfold or retract.

3. The coal seam borehole enlargement device according to claim 1, characterized in that, The blade assembly includes a rotating wheel and a blade body, the blade body being fixed to the rotating wheel; the drive mechanism includes drive teeth disposed on the rotating wheel and a rack meshing with the drive teeth.

4. The coal seam borehole enlargement device according to claim 3, characterized in that, The protective mechanism surrounds the meshing area between the drive tooth and the rack to prevent external particles from entering. The protective mechanism includes: At least one first baffle rotates with the rotating wheel; The second baffle is fixedly installed and slides in contact with the outer arc surface of the rotating wheel; The fixed seat slides in conjunction with the first baffle to form a closed or semi-closed isolation of the meshing area.

5. The coal seam enlargement device according to claim 4, characterized in that, The fixed base has an arc surface on one side that matches the curvature of the first baffle; the second baffle is on the same horizontal plane as the axis of the rotating wheel and is slidably connected to the outer side of the rotating wheel.

6. The coal seam borehole enlargement device according to claim 3, characterized in that, The hydraulic adjustment assembly includes: The piston block can move axially under fluid pressure; The slider is linked to the piston block and carries the rack.

7. The coal seam enlargement device according to claim 6, characterized in that, The enlargement unit is provided with a straight pipe and a diversion pipe; the piston block is sleeved on the outside of the straight pipe; the slider is slidably sleeved on the outside of the diversion pipe.

8. The coal seam enlargement device according to claim 7, characterized in that, The straight pipe is used to guide fluid to the drill bit of the drilling unit; the diverter pipe is used to guide fluid to the second injection port in the working area of ​​the cutter blade assembly.

9. The coal seam borehole enlargement device according to claim 8, characterized in that, The axial movement of the piston block controls the on / off state and flow rate of fluid entering the diversion pipe.

10. The coal seam borehole enlargement device according to claim 9, characterized in that, The piston block is provided with a flow-diverting hole, and the inner wall of the expansion unit is provided with a water outlet that communicates with the flow-diverting pipe. When the piston block moves, the overlapping area of ​​the flow-diverting hole and the water outlet changes, thereby adjusting the flow rate to the flow-diverting pipe.

11. The coal seam borehole enlargement device according to claim 10, characterized in that, The opening shape of the water outlet gradually expands along the moving direction of the piston block, so that during the deployment of the blade assembly, the flow rate to the diversion pipe increases with the increase of the deployment angle.

12. The coal seam borehole enlargement device according to claim 6, characterized in that, The hydraulic adjustment assembly also includes a reset spring sleeved between the piston block and the inner wall of the expansion unit, used to drive the piston block to reset when the fluid pressure decreases.

13. The coal seam borehole enlargement device according to claim 1, characterized in that, The hole-expanding unit includes an expanding block, which has a receiving groove for accommodating the blade assembly and a converging groove for accommodating the hydraulic adjustment assembly.

14. The coal seam enlargement device according to claim 7, characterized in that, The drilling unit includes a drill bit, which has a first injection port connected to the straight pipe for cooling and chip removal during drilling operations.

15. The coal seam enlargement device according to claim 1, characterized in that, Two blade assemblies are symmetrically arranged, respectively located on opposite sides of the hole enlarging unit.

16. The coal seam enlargement device according to claim 7, characterized in that, The outside of the straight pipe is provided with a limiting ring to restrict the axial movement range of the piston block.

17. The coal seam enlargement device according to claim 7, characterized in that, The slider has a through groove inside to accommodate the diverter tube, so as to ensure that the slider slides stably along the diverter tube.

18. A method for enlarging coal seams, characterized in that, Using the coal seam enlargement apparatus according to any one of claims 1 to 17 includes the following steps: Drilling stage: Inject fluid at the first pressure value into the device, so that the fluid is mainly ejected through the drilling unit to carry out drilling operations. At this time, the cutter blade assembly is in the receiving position. Hole enlargement stage: The fluid pressure is increased to the second pressure value, which drives the hydraulic adjustment component to operate, causing the blade assembly to unfold to the hole enlargement position. At the same time, some fluid is ejected through the hole enlargement unit to carry out hole enlargement and flushing operations.

19. The coal seam enlargement method according to claim 18, characterized in that, It also includes the recovery phase: The fluid pressure is reduced, causing the hydraulic adjustment component to move in the opposite direction under the action of the reset mechanism, which drives the blade assembly to retract to the receiving position. During the retraction process, fluid is continuously or intermittently ejected from the orifice expansion unit.

Images