A reverse circulation large-diameter bundled type down-the-hole hammer reamer and a method for discharging residue

Abstract

The application provides a reverse circulation large-diameter bundled type hole hammer reamer bit and a residue discharging method, and specifically comprises a reamer bit surrounding cylinder, a gas distribution chamber, a center tube assembly, a hole hammer and a residue suction port arranged at the bottom of the center tube and used for sucking the crushed rock residue into the drill rod through negative pressure to realize rock residue discharging. The application is aimed at the reaming drilling of the large-diameter water-bearing stratum of the bedrock, and the only residue suction port is arranged at the bottom of the center tube. The hole hammer tail gas forms a suction air flow to push the liquid in the borehole to return to the ground surface from the residue suction port, and the water level is lifted by the hole hammer tail gas pressure, so that the stable and continuous reverse circulation residue discharging effect is realized, the drilling efficiency of the large-diameter bundled type hole hammer is improved, and the stable and continuous residue discharging effect is extremely good in the construction application.

Description

Technical Field

[0001] This invention relates to the field of drill bit technology, and in particular to a reverse circulation large-diameter bundled down-the-hole hammer reamer drill bit and a slag removal method. Background Technology

[0002] In bridge construction, large-scale projects such as cross-river and cross-sea bridges require deeper and larger diameter pile foundation holes to meet the high requirements of bridge structures for load-bearing capacity and stability. In mining, to improve blasting efficiency and ore production, the diameter and depth of blasting holes in open-pit mines are constantly increasing. The construction of ventilation shafts and raises in underground mines also requires large-diameter drilling technology. Traditional drilling equipment and drill bits are insufficient to meet the construction needs of these complex projects, especially when facing hard rock and complex strata, resulting in problems such as low drilling efficiency, poor hole accuracy, and difficulties in slag removal. Large-diameter bundled reverse circulation down-the-hole hammer reamer drill bits have emerged to meet the ever-evolving needs of the engineering construction field.

[0003] Geological conditions are complex and diverse, with significant differences in stratigraphic structure and rock properties across different regions. In heterogeneous strata, ordinary drill bits are prone to borehole deviation and accelerated wear due to uneven stress. In fault fracture zones, the loose strata are highly susceptible to collapse, making borehole formation impossible. In water-rich strata, cuttings are difficult to remove, easily causing borehole blockage. While large-diameter bundled reverse circulation down-the-hole hammer drill bits or reamers can solve some of these problems, the issue of achieving stable and continuous reverse circulation for cuttings removal remains unresolved. There are specific serious technical defects: Generally, drill bits have two or more slag suction ports on the bottom surface. Without air-lift reverse circulation power, they rely on the pressure of the down-the-hole hammer exhaust gas for passive reverse circulation. This can cause the slag suction ports to enter the central channel, and the pressure will partially cancel each other out. Under the water pressure inside the hole, it is difficult to achieve reverse circulation slag removal. Moreover, the drill bit body cannot be sealed to the hole wall. Most of the down-the-hole hammer exhaust gas circulates back to the slag through the annular gap between the drill bit and the hole wall, which prevents rock cuttings from returning to the outside of the hole and also poses a risk of burying the drill bit. Summary of the Invention

[0004] In view of this, the present invention proposes a reverse circulation large-diameter bundled down-the-hole hammer reamer drill bit and a slag removal method.

[0005] Specifically, the aforementioned reverse-circulation large-diameter bundled down-the-hole hammer reamer includes a drill bit casing; a gas distribution chamber at the top of the drill bit casing for providing high-pressure gas to the down-the-hole hammers and distributing and controlling the gas; a central tube assembly connected to the drill rod at the center of the drill bit casing for introducing high-pressure gas into the impactor and simultaneously discharging rock cuttings; and several down-the-hole hammers arranged circumferentially along the central tube assembly inside the drill bit casing for using the energy of compressed air to drive the reciprocating motion of internal pistons to generate impact force. The down-the-hole hammers include: Several impactors evenly arranged around the central tube; Each impactor is provided with a gas passage for connecting the impactor to the gas distribution chamber and an impactor rear connector for torque transmission at the top. A front connector for transmitting torque and axial force is provided at the bottom of the drill bit casing; A hammerhead is provided at the bottom of the downhole hammer for directly impacting and crushing rocks; And an impactor casing for protecting the impactor, provided on the outside of the impactor; The piston cylinder of the impactor is connected to the air distribution chamber through the air guide pipe, and the central pipe is connected to the air distribution chamber through the air inlet hole opened on the central pipe wall. The bottom of the impactor casing is provided with a front connector fixing plate. The square hole passing through the impactor on the front connector fixing plate is fixed to the square shape of the front connector to prevent the front connector from loosening. It also includes a slag suction port at the bottom of the central tube for sucking the crushed rock debris into the drill pipe through negative pressure to achieve rock debris discharge.

[0006] Based on the above scheme, it also includes: a bottom lip plate fitted on the hammer head and the central tube, wherein the bottom of the hammer head is 15mm-20mm higher than the bottom lip plate.

[0007] Based on the above scheme, the bottom lip plate partially surrounds the hammer head on the side closest to the hammer head; The hammer head, located on the outer edge of the drill bit, is exposed and in contact with the borehole wall, and is used to protect the bottom lip plate, the front joint fixing plate, and the outer edge of the drill bit casing from wear during drilling.

[0008] Based on the above solution, it also includes: setting an intermediate fixing plate at the middle part of the central tube; The central holes of the gas distribution chamber, intermediate fixing plate, front connector fixing plate and bottom lip plate are fitted onto the central tube and together with the drill bit casing form a binding body. During drilling, the torque and speed are transmitted through the central tube assembly to drive the binding body to rotate and drill.

[0009] Based on the above scheme, it also includes: a front guide provided at the bottom of the central tube for guiding the drilling direction; The front guide is in the form of a multi-wing scraper drill bit or a spiral taper drill bit.

[0010] Based on the above scheme, the front guide includes multiple wing plates, and an arc transition structure is provided at the bottom of the central tube at the connection point of adjacent wing plates.

[0011] Based on the above scheme, the distance between the slag suction port and the hammer head is 200mm-350mm.

[0012] In addition, the present invention also provides a method for slag removal of a large-diameter bundled down-the-hole hammer reamer bit with reverse circulation. When the drill bit is working, the exhaust gas of the down-the-hole hammer forms a vortex flow that pushes the liquid in the borehole back to the surface from the slag suction port at the bottom of the central tube, so as to carry out continuous reverse circulation slag removal.

[0013] Compared with existing equipment, this invention sets a unique slag suction port at the bottom of the drill bit's central tube, at a certain distance from the bottom of the down-the-hole hammer. Through the principle of fluid entrainment and siphon effect, the exhaust gas of the down-the-hole hammer is entrained in a certain space and enters the slag suction port. The exhaust gas pressure lifts the water level to a certain height (the faucet or power head of the drilling rig), and the slag is stably and continuously discharged to the sedimentation tank on the ground through the siphon effect, realizing efficient reverse circulation drilling. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the existing large-diameter bundled down-the-hole hammer structure (showing that the pressure of multiple slag suction ports cancels each other out). Figure 2 This is a schematic diagram of the structure of a reverse circulation large-diameter bundled down-the-hole hammer reamer according to an exemplary embodiment; Figure 3 This is a structural schematic diagram of a reverse circulation large-diameter bundled down-the-hole hammer reamer according to an exemplary embodiment (showing an assembly schematic diagram of the air chamber and high-frequency backseat). Figure 4 for Figure 2 A sectional view along line AA (showing a schematic diagram of the assembly of the drill bit casing and the down-the-hole hammer). Figure 5 This is a schematic diagram of the structure of a submersible hammer on a binding body according to an exemplary embodiment; Figure 6 This is a schematic diagram showing the assembly state of the bottom lip plate, hammer head, and center tube according to an exemplary embodiment. Figure 7 for Figure 2 BB-direction sectional view (showing the positional relationship of the central tube, front connector fixing plate and front connector). Figure 8 This is a schematic diagram illustrating the assembly state of the front guide vane and the central tube according to an exemplary embodiment; Figure 9 This is a schematic diagram illustrating the working principle of a slag suction port according to an exemplary embodiment (showing the slag suction effect and siphon effect of the slag suction port during operation). Detailed Implementation

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and do not constitute any limitation thereof.

[0016] The current development status of large-diameter bundled reverse circulation down-the-hole hammer technology is as follows: (1) Early technological foundation: The earliest technical reference can be traced back to the Loma drill bit design in the United States, which laid the foundation for subsequent technological developments. However, it has the following disadvantages: ① Low rock penetration efficiency: All the working faces of the impactors are on the same plane, requiring simultaneous hammering, crushing, and slag removal of the entire large-diameter rock surface at the bottom of the borehole, resulting in low rock penetration efficiency; ② Significant energy waste: Due to the above working method, energy cannot be effectively concentrated and utilized, causing a large amount of energy waste; ③ Prone to drill deviation: During drilling, the borehole is prone to deviating from the predetermined direction, affecting construction accuracy and quality. (2) Technological breakthroughs from 2014 to 2015: In 2013, the applicants, Team 139 of Shaanxi Provincial Bureau of Coal Geology and Hydrological Team of Shaanxi Provincial Bureau of Coal Geology, filed a patent with the patent number 201320574406.1 and the authorization announcement date was April 9, 2014. The patent was entitled "Cluster-type Reverse Circulation Pneumatic Down-the-Hole Hammer".

[0017] The original idea was to set four slag suction ports at the bottom of the drill bit body, with a 0.5mm gap between the bundle body and the borehole wall. The bottom lip plate on the drill bit bundle body was used to seal the borehole wall, and reverse circulation was achieved by relying on the exhaust gas pressure of the down-the-hole hammer. However, in actual application, the sealing effect was very poor. Most of the down-the-hole hammer exhaust gas carried rock powder into the drill bit during forward circulation, and reverse circulation could not be achieved.

[0018] The advantage of this technology is that it can perform impact work simultaneously, achieve high-efficiency drilling, and realize reverse circulation drilling. It is particularly suitable for high-efficiency air drilling in large-diameter aquifers, and overcomes the technical problems of poor rock powder carrying capacity of circulating medium in aquifers, large safety hazards in the borehole, and inability to achieve continuous and rapid drilling in forward circulation drilling.

[0019] The disadvantages are: ① The rock surface is not complete: Due to the shape and spatial arrangement of the central impactor drill bit and the outer impactor drill bit, the rock surface formed by the down-the-hole hammer drill is not a complete rock surface. A large-diameter and unbroken rock column will be formed between every two impactors, which will resist the drilling progress. This means that the drill must be impacted and rotated more times to completely break the rock and drill deeper, which reduces the drilling speed.

[0020] ② Uneven impact energy and easy hole deviation: When compressed air is delivered to the impactor through the pipeline, it is not evenly distributed. Different impactors produce uneven impact energy, resulting in different rock cavity depths during drilling, which can easily cause hole deviation.

[0021] ③ Difficult and costly installation: The threaded connection between the rear connector of each down-the-hole hammer impactor and the gas distribution chamber is not equipped with a backstop device, which may cause the down-the-hole hammer to fall into the borehole during operation and cause drilling accidents. The structure increases the difficulty and certain danger of installing and disassembling the down-the-hole hammer; in addition, the drill string structure is not compact enough and the maintenance cost is high.

[0022] (3) Technological applications and improvements at the end of 2014: By the end of 2014, the reverse circulation down-the-hole hammer developed by Xi'an Coal Research Institute did not perform well in construction in Jincheng, Shanxi Province. This indicates that although the technology has made initial breakthroughs, it still needs further improvement and refinement in practical applications.

[0023] On December 8, 2014, the applicant, Xi'an Research Institute Co., Ltd. of China Coal Technology & Engineering Group, filed a patent application with the patent number 201410747538.9 and the publication date was April 8, 2015. The patent title was "Reverse Circulation Bundle Down-the-Hole Hammer for Hole Enlargement".

[0024] This patent describes a device comprising an upper connector, an inner tube, an outer tube, an air distribution chamber, a pneumatic down-the-hole hammer, a central tube, and a sealing plate. The upper connector and the outer tube are sequentially fitted around the outer tube from top to bottom. The air distribution chamber is fitted onto the upper part of the outer tube, and the sealing plate is fitted onto the lower part of the central tube. Several pneumatic down-the-hole hammers are positioned between the air distribution chamber and the sealing plate. When connected to a matching double-walled drilling system, this device can form a reverse circulation channel within the borehole during reaming in rock sections, achieving reverse circulation slag removal and fully leveraging the high-efficiency rock-breaking advantage of the pneumatic down-the-hole hammer.

[0025] The disadvantages are as follows: ① The drill bit is easily worn out: the alloy of the integral down-the-hole hammer drill bit wears out relatively quickly. It needs to be repaired and the alloy replaced (hammer head replaced) after drilling 100-300 meters into hard rock.

[0026] ② Significant limitations in maintenance: Due to the large diameter and weight of integral down-the-hole hammer drill bits, disassembling the impactor and drill bit requires a specialized disassembly platform. Only professional manufacturers possess such large disassembly platforms. Therefore, drill bit repair must be performed by professional manufacturers. In actual construction, even if there are spare drill bits available on site, the large size and weight of integral down-the-hole hammer drill bits, along with the need for specialized tools, make it impossible to disassemble the impactor and drill bit on site for replacement.

[0027] ③ High cost: The broken alloy on the drill bit needs to be thoroughly removed with a special EDM machine, then the drill bit body needs to be repaired by electric welding, heat treated, and then re-drilled to insert the alloy. Repairing a drill bit can be more expensive than installing alloy on a new drill bit. Drill bits larger than 600mm generally take 7-10 days to repair.

[0028] In summary, the technology of large-diameter bundled reverse circulation down-the-hole hammer has undergone a process from basic design to practical application and improvement, from the early Loma drill bit design in the United States to the patent applications of Shaanxi Provincial Bureau of Coal Geology and Xi'an Research Institute of China Coal Technology and Engineering Group Co., Ltd., and other domestic manufacturers developing bundled reverse circulation down-the-hole hammer drill bits. However, for those skilled in the art, the conventional technical means is to design multiple slag suction ports to increase the contact area with slag and allow more slag to be sucked in at the same time, but this seriously ignores the defects in this design.

[0029] like Figure 1 The existing technology shown has two or more slag suction ports on the bottom surface of the drill bit. The slag suction ports are located on the front joint fixing plate on the upper part of the bottom lip plate 7. The exhaust gas from the hammer reaches the slag suction port on the upper part of the hammer in a swirling motion. During this process, the pressure decreases. There is no air lift reverse circulation power. It mainly relies on the pressure of the exhaust gas from the down-the-hole hammer for passive reverse circulation. After the exhaust gas from the hammer reaches the slag suction port, the pressure decreases. This causes the slag suction port to enter the central channel, and the pressure partially cancels each other out. Under the water pressure in the hole, it is difficult to achieve reverse circulation slag removal. At the same time, the drill bit body cannot be sealed with the hole wall. Most of the exhaust gas from the down-the-hole hammer circulates back to the slag through the annular gap between the drill bit and the hole wall, which prevents rock cuttings from returning to the outside of the hole and also poses a risk of burying the drill bit.

[0030] To address the aforementioned technical problems, this application provides a specific embodiment of a reverse circulation large-diameter bundled down-the-hole hammer reamer drill bit, such as... Figure 2 The aforementioned large-diameter reverse circulation bundled down-the-hole hammer reamer includes: Drill bit casing 1; A gas distribution chamber 2 is provided at the top of the drill bit casing 1 to provide high-pressure gas to the down-the-hole hammer 4 and to distribute and control the gas. A central tube assembly 3, which is connected to the drill rod and located at the center of the drill bit casing 1, is used to introduce high-pressure air into the impactor and discharge rock cuttings. The central tube assembly 3 includes a central tube 3-1 and an inner tube 3-2 coaxially arranged inside the central tube 3-1. The high-pressure air enters the air distribution chamber 2 through the annular gap between the central tube 3-1 and the inner tube 3-2 and through the vent hole on the wall of the central tube 3-1 at the connection between the central tube 3-1 and the air distribution chamber 2. Inside the drill bit casing 1, along the central tube 3-1, is a downhole hammer 4 that uses the energy of compressed air to drive the reciprocating motion of the internal piston to generate impact force. A hammerhead 4-4 is provided at the bottom of the downhole hammer 4 for directly impacting and crushing rocks; A slag suction port 9 is provided at the bottom of the central tube 3-1 to suck the crushed rock debris into the drill pipe through negative pressure so as to discharge the rock debris.

[0031] The central tube assembly 3 includes a connecting joint or connecting flange 3-4 that connects to the drill string at the top to transmit torque and speed. A key block 3-5 for transmitting torque is provided on the connecting flange 3-4. A reinforcing rib 3-3 is provided between the central tube 3-1 and the connecting flange 3-4 to strengthen the connection strength between the central tube 3-1 and the connecting flange 3-4.

[0032] The above scheme involves setting a single slag suction port 9 at the bottom of the drill bit center tube 3-1, at a certain distance from the bottom of the retracting hammer 4-4. This distance is related to the volume and pressure of the exhaust gas discharged by the downhole hammer on the binding body. For example, when the 6-inch impactor breaks rock, the volume of exhaust gas discharged is approximately 20m³. 3 At a speed of 0.5-0.6 MPa and a pressure of 0.5-0.6 MPa, a distance of 200-300 mm provides good slag removal efficiency; when the exhaust gas volume is 24 m³ / min... 3 At a pressure of 0.5-0.6 kJ / min, a distance of 220-320 mm provides ideal slag removal efficiency. Based on this practical data, the exhaust gas volume and pressure of down-the-hole hammers of the same or different specifications can be roughly converted to this distance. In this invention, the slag suction port 9 is located at the bottom end of the central tube 3-1. Regardless of the number of down-the-hole hammers 4 arranged on the circumference, there is no need to consider the position of the slag suction port 9 on the bottom lip plate 8 and the front connector fixing plate 7 of the central tube 3-1. This ensures that the down-the-hole hammers 4 are evenly distributed on the circumference, avoiding uneven weight distribution during drill bit rotation.

[0033] Specifically, the central tube assembly 3 includes a central tube 3-1 and an inner tube 3-2 disposed inside the central tube 3-1. Air vents are provided on the central tube 3-1. High-pressure air enters the air distribution chamber 2 through the air vents on the central tube 3-1 via the annular gap between the inner tube 3-2 and the central tube 3-1. The annular gap serves as the initial channel for high-pressure air to enter the chamber, providing a specific flow path for the high-pressure air, allowing it to be introduced from an external air source through equipment such as drill pipes. This design ensures that the air has a certain degree of aggregation and guidance before entering the chamber, allowing the air to enter the chamber more evenly and providing a stable air source for subsequent impact work. Simultaneously, the annular gap can buffer and regulate the high-pressure air pressure to a certain extent. When high-pressure air enters from a high-pressure source such as drill pipes, the annular gap can mitigate sudden changes in air pressure, preventing excessive pressure impact from damaging the chamber and other components. Furthermore, it can also perform preliminary adjustments to the air pressure and flow rate according to system requirements, making the air pressure entering the chamber more stable and suitable.

[0034] like Figure 3As shown, in a specific implementation scheme, the air distribution chamber 2 includes an air chamber upper cover plate 2-1, a high-frequency rear seat 2-3 connected to the upper end of the impactor casing 4-5, and an air chamber casing 2-2 connected to the high-frequency rear seat 2-3. The high-frequency rear seat 2-3 can ensure that the reaction force generated by the high-frequency impact work of all impactor pistons does not cause the air distribution chamber 2 to deform.

[0035] Specifically, the center hole on the upper cover plate 2-1 of the air chamber is welded to the center tube 3-1 of the high-frequency rear seat 2-3. After the impactor rear connector 4-2 is installed, a relatively closed space is formed, which confines the high-pressure air in the air distribution chamber 2 and prevents air leakage into the external environment. This sealing structure can ensure the pressure stability in the air chamber, provide a stable gas pressure environment for the piston movement of the down-the-hole hammer, and improve the working efficiency and reliability of the down-the-hole hammer.

[0036] As a specific implementation plan, such as Figure 2 and Figure 4 As shown, the downhole hammer 4 includes four impactors 4-1 evenly arranged around the central tube 3-1, and an impactor rear connector 4-2 at the top of the impactors 4-1 for connecting the impactors 4-1 to the air distribution chamber 2. The rear connector 4-2 passes through the air distribution chamber 2 and is fixed by a fixing thread device 5. The impactors 4-2 are fixed to the air chamber cover plate 2-1 on the upper part of the air distribution chamber 2 by fixing lock bolts. The impactor front connector 4-3 connects the hammer head 4-4 to the impactor 4-1. An impactor casing 4-5 is provided on the outside of the impactors 4-1 to protect the impactors, maintain the shape of the air chamber, and assist in guiding the airflow. The two ends of the impactors 4-5 are welded to the high-frequency rear seat 2-3 and the front connector fixing plate 7 of the air distribution chamber 2, respectively.

[0037] The aforementioned threaded fixing device 5 includes a fixing nut 5-1 and a backstop bolt 5-2.

[0038] like Figure 5 As shown in the illustration, in a specific implementation, the down-the-hole hammer 4 includes four sets of impactors 4-1, impactor rear connectors 4-2, front connectors 4-3, hammer heads 4-4, and peripheral pipes 4-5, evenly arranged around the central tube 3-1. The central tube 3-1 is connected to the air distribution chamber 2 through an air inlet hole on the tube wall. The air distribution chamber 2 is connected to the piston cylinder in the down-the-hole hammer through air guide pipes. In the prior art, the hammer head 4-4 is generally exposed and cannot rotate on its own, which easily leads to wear on the outer side of the hammer head. To solve this technical problem, the spline on the hammer handle is removed. Although the hammer head cannot rotate on its own, it will rotate due to friction with the hole wall during overall rotary drilling, avoiding wear only on the outer part. That is, the hammer head 4-4 on each down-the-hole hammer 4 rotates under the action of friction with the hole wall, and the circumference of the hammer head 4-4 is worn evenly, extending the service life of the hammer head 4-4.

[0039] like Figure 6 As shown, the bottom of the down-the-hole hammer 4 is provided with a bottom lip plate 8, which is fitted onto the hammer head 4-4 and the central tube 3-1. Specifically, the hammer head 4-4 is embedded in the circumferential hole of the bottom lip plate 8, and the bottom of the hammer head 4-4, including the hard alloy part, protrudes 15-20mm above the bottom lip plate. This design is beneficial for impacting and breaking fresh rock in the borehole. The energy of the piston impact motion of the impactor 4-1 is transferred to the hammer head 4-4 to perform high-frequency impact on the rock, breaking the rock. At the same time, the shape and material of the bottom lip plate 8 also affect the rock breaking effect and wear resistance.

[0040] In one specific embodiment of the bottom lip plate 8, the bottom lip plate 8 partially surrounds the hammer head 4-4 on the side closest to it. The outer diameter of the bottom lip plate 8 is 10mm smaller than the outer circumferential diameter of the outermost hammer head 4-4. The distance between the outer circumferential sidewall of the embedded hammer head 4-4 and the hole sidewall of the bottom lip plate 8 is 5mm. This ensures that the hammer head does not rub against the bottom lip plate during impact, and also ensures that large rock fragments do not get stuck in the gap between the hammer head 4-4 and the bottom lip plate 8, thus preventing the drill bit from affecting the rock impact effect. Specifically, the carbide ball on the bottom surface of the hammer head 4-4 impacts the rock, and the side is pre-embedded with a diameter-protecting alloy, resulting in less friction and wear with the borehole wall. In other words, the diameter of the bottom lip plate 8 is 10mm smaller than the outer circumcircle diameter of the four hammer heads. This design, with the bottom lip plate 8 filling the large space between the hammers 4-4, ensures that large rock cuttings in the hole will not get stuck in the space between the hammers 4-4 to support the binding drill bit. Large rock cuttings must be pressed to the bottom of the drill bit, so that the rotating hammer 4-4 can hit the large rock cuttings and break them into small particles that are easily discharged out of the hole by the airflow into the slag suction port 9. At the same time, another function of the bottom lip plate 8 is to prevent large rock cuttings at the bottom of the hole from abrading the sides of the hammers.

[0041] like Figure 4 As shown, the drill bit casing 1 forms a closed space, enclosing the down-the-hole hammer 4 and the intermediate fixing plate 6. The drill bit casing 1, the central tube 3-1, the high-frequency rear seat 2-3 of the air distribution chamber 2, the intermediate plate 6, the impactor front connector fixing plate 7, and the bottom lip plate 8 are combined into a complete bundled drill bit body. After the down-the-hole hammer 4 is installed, the drill bit inside the borehole rotates under the rotation of the drill rod, driving the central tube assembly 3 to rotate. At the same time, the entire bundled body rotates, and the down-the-hole hammer 4 installed on the bundled body rotates synchronously. High-pressure air drives the piston of the impactor 4-1 to impact the high-frequency hammer head 4-4. The hammer head 4-4 transmits the impact energy to the rock at the bottom of the hole for high-frequency impact crushing. Meanwhile, the slag discharge port 9 and other slag discharge components assist in discharging the crushed rock slag. The entire process is completed in a coordinated manner under the drive of the impactor.

[0042] As a hole-reaming component of a drill bit, such as Figure 7As shown, it also includes: a front connector fixing plate 7 for transmitting torque and axial force, set at the bottom of the drill bit casing 1. The center hole of the front connector fixing plate 7 is welded and fixed to the center tube 3-1, and the center of the square holes arranged on the circumference is aligned with the center of the down-the-hole hammer 4; when installing the down-the-hole hammer 4, the outer square of the impactor front connector 4-3 and the square hole set on the front connector positioning plate 7 are fitted with a clearance to fix the front connector 4-3 and prevent it from rotating and disengaging. The front connector fixing plate 7 is welded to the bottom lip plate 8, wherein the bottom lip plate 8 partially surrounds the hammer head 4-4, and the outer edge of the drill bit body is exposed and in contact with the hole wall, protecting the bottom lip plate 8, the upper front connector fixing plate 7 and the outer edge of the drill bit casing 1 from wear during drilling.

[0043] like Figure 8 As shown in the figure, as a specific implementation, the reverse circulation large-diameter bundled down-the-hole hammer reamer bit further includes: a front guide provided at the bottom of the central tube 3-1 for guiding the drilling direction, wherein the front guide is in the form of a multi-wing scraper bit or a spiral cone tip bit.

[0044] The front guide includes multiple wing plates 10. Specifically, each wing plate 10 is a three-wing scraper or a multi-wing scraper, and the bottom bevel of the wing plate 10 is inlaid with alloy. The wing plates 10 are welded to the central tube 3-1 and form a slag suction port 9.

[0045] like Figure 9 As shown, the slag suction port 9, as an important component of the reverse circulation slag discharge system, is located at the bottom of the drill bit. It uses negative pressure to suck the crushed rock slag into the drill pipe, thereby discharging the rock slag and ensuring the continuous operation of the drilling.

[0046] To further increase the area of ​​the slag suction port 9, an arc-shaped transition structure is provided at the bottom of the central tube 3-1, at the connection point of the adjacent flange 10. This design increases the area of ​​the slag suction port 9, which is beneficial for slag suction. According to the principles of fluid mechanics, fluid flows through an arc with less resistance than through a straight connection, allowing for more natural flow and less energy loss. When the drill bit is working, the broken rock cuttings flow towards the slag suction port 9 under negative pressure. The arc-shaped slag suction port 9 allows the rock cuttings to enter the slag suction channel more smoothly, reducing blockage and accumulation of rock cuttings at the slag suction port 9, and improving the efficiency and stability of slag suction. Moreover, regardless of the number of flanges 10 combined, a single slag suction channel is formed at the bottom of the central tube 3-1. The mixture of bottom hole liquid, rock cuttings, and down-the-hole hammer exhaust gas enters the central tube 3-1 through the single slag suction port 9 at the bottom of the central tube 3-1.

[0047] Furthermore, in order to achieve the desired siphon effect, the borehole is kept full of water during the drilling process.

[0048] This invention is designed for enlarged borehole drilling in large-diameter water-bearing bedrock formations. A unique slag suction port is set at the bottom of the central pipe. The exhaust gas of the down-the-hole hammer forms an entrainment airflow that pushes the liquid in the borehole back to the surface from the slag suction port. The water level rises by airlifting the exhaust gas pressure of the down-the-hole hammer, achieving a stable and continuous reverse circulation slag removal effect. This improves the drilling efficiency of large-diameter bundled down-the-hole hammers and has an excellent stable and continuous slag removal effect in construction applications.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A reverse circulation large-diameter bundled down-the-hole hammer reamer bit, characterized in that, The device includes a drill bit casing (1), a gas distribution chamber (2) at the top of the drill bit casing (1) for providing high-pressure gas to the down-the-hole hammers (4) and distributing and controlling the gas, a central tube assembly (3) at the center of the drill bit casing (1) connected to the drill rod for introducing high-pressure gas into the impactor and discharging rock cuttings; and several down-the-hole hammers (4) arranged circumferentially along the central tube assembly (3) inside the drill bit casing (1) for using the energy of compressed air to drive the internal pistons to reciprocate and generate impact force. The downhole hammer (4) includes: Several impactors (4-1) are evenly arranged around the central tube (3-1). Each of the impactors (4-1) is provided with a gas passage for connecting the impactor (4-1) and the gas distribution chamber (2) and an impactor rear connector (4-2) for torque transmission. A front connector (4-3) for transmitting torque and axial force is provided at the bottom of the drill bit casing (1). A hammerhead (4-4) is provided at the bottom of the downhole hammer (4) for directly impacting and crushing rocks. And an impactor casing (4-5) provided on the outside of the impactor (4-1) for protecting the impactor (4-1). The piston cylinder of the impactor (4-1) is connected to the air distribution chamber (2) through the air guide pipe, and the central pipe (3-1) is connected to the air distribution chamber (2) through the air inlet hole opened on the wall of the central pipe (3-1). The bottom of the impactor casing (4-5) is provided with a front connector fixing plate (7). The square hole on the front connector fixing plate (7) passing through the impactor (4-1) matches the square shape of the front connector (4-3) to prevent the front connector (4-3) from loosening. It also includes: a slag suction port (9) provided at the bottom of the central tube (3-1) for sucking the crushed rock slag into the drill pipe through negative pressure to achieve rock slag discharge.

2. The reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 1, characterized in that, Also includes: A bottom lip plate (8) is fitted on the hammer head (4-4) and the center tube (3-1), with the bottom of the hammer head (4-4) protruding 15mm-20mm above the bottom lip plate (8).

3. The reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 2, characterized in that, The bottom lip plate (8) partially surrounds the hammer (4-4) on the side near the hammer (4-4). Among them, the hammer (4-4) is located on the outer edge of the drill bit and is exposed and in contact with the hole wall. It is used to protect the outer edge of the bottom lip plate (8), the front joint fixing plate (7) and the drill bit casing (1) from wear during drilling.

4. The reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 1, characterized in that, Also includes: An intermediate fixing plate (6) is provided in the middle part of the central tube (3-1); The central holes of the gas distribution chamber (2), the intermediate fixing plate (6), the front connector fixing plate (7) and the bottom lip plate (8) are fitted onto the central tube (3-1) and together with the drill bit casing (1) form a binding body; During drilling, the torque and speed are transmitted through the central tube assembly (3) to drive the binding body to rotate and drill.

5. A reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 1, characterized in that, Also includes: A front guide is provided at the bottom of the central tube (3-1) to guide the drilling direction; The front guide is in the form of a multi-wing scraper drill bit or a spiral cone drill bit.

6. A reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 5, characterized in that, The front guide includes multiple wing plates (10), and an arc transition structure is provided at the bottom of the central tube (3-1) at the connection point of adjacent wing plates (10).

7. A reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to claim 1, characterized in that, The distance between the slag suction port (9) and the hammer (4-4) is 200mm-350mm.

8. A method for removing slag from a large-diameter, bundled down-the-hole hammer reamer bit with reverse circulation, characterized in that, When the reverse circulation large-diameter bundled down-the-hole hammer reamer bit according to any one of claims 1-7 is used, the exhaust gas of the down-the-hole hammer (4) forms a vortex flow that pushes the liquid in the borehole back to the surface from the slag suction port (9) at the bottom of the central tube (3-1) to carry out continuous reverse circulation slag discharge.

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