Double-wall drilling tool and method for dynamic directional drilling of water-containing broken soft coal in underground coal mine

Abstract

The double-wall drilling tool comprises a double-wall water tank, a double-wall drilling rod, a double-wall non-magnetic drilling rod, a double-wall spraying and pumping short section, a pneumatic screw drilling tool and a drilling bit which are connected in sequence, and double channels allowing high-pressure gas, guniting slurry and accumulated water in a hole to pass through are formed. A double-wall drilling tool is adopted, a double-medium flowing channel is formed, wall protection while drilling is achieved in the pneumatic directional drilling process under the condition of the water-containing broken soft coal seam, one part of slurry permeates into micro cracks of the hole wall to play a role in consolidating and reinforcing the hole wall, the other part of slurry can form a wall protection layer with a certain thickness on the periphery of the hole wall of the drill hole, and the effect of protecting the wall is achieved. The effect of supporting the hole wall to be stable is achieved; and the accumulated water in the hole can be reversely pumped and drained by utilizing underground coal mine extraction high negative pressure and through double channels formed by the double-wall drill rod, so that the problem that the hole is difficult to form when meeting water during pneumatic directional drilling is solved.

Description

Technical Field

[0001] This invention belongs to the technical field of coal mine drilling, and relates to a double-walled drilling tool and drilling method for pneumatic directional drilling in water-bearing, soft coal seams underground. Background Technology

[0002] Near-horizontal directional drilling technology in coal mines has been widely applied in drilling operations for coal mine gas control, water hazard prevention, and detection of hidden disaster-causing factors due to its advantages such as controllable borehole trajectory and large single-hole coverage, achieving significant results. Currently, underground directional drilling technologies in coal mines mainly include hydraulic directional drilling technology and pneumatic directional drilling technology. Pneumatic directional drilling technology is mainly used for drilling in soft coal seams. Due to the use of gas to remove slag, it has the advantage of less disturbance to the borehole wall and has a better ability to form holes under soft coal seam conditions. In recent years, it has been promoted and applied on a large scale in mining areas with soft coal seams. However, some shortcomings have gradually emerged in the application process, mainly: (1) There are still different degrees of hole collapse during the drilling process. Frequent hole sweeping and slag removal are required during the drilling process, resulting in low drilling efficiency and easy drilling accidents, which restricts the efficient long-distance hole formation; (2) There are different degrees of hole collapse after the hole is formed, which can easily block the gas extraction channel. Therefore, after the hole is formed, a protective screen pipe needs to be installed. However, hole collapse can also easily cause the protective screen pipe to be blocked, which restricts the efficient gas extraction from the hole; (3) When encountering water-bearing strata, water will accumulate in the hole to a certain extent, which will cause coal slag and water to mix and form coal slurry, which will adhere to the borehole wall and drill rod wall. It is difficult to remove it from the hole using high-pressure gas, which will eventually make it difficult to form a hole. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a double-walled drilling tool and method for pneumatic directional drilling in water-bearing, fractured, and soft coal seams in underground coal mines. The tool has a simple structure and is easy to operate, enabling drilling and wall protection with grouting and drainage of water accumulated in the borehole during the pneumatic directional drilling process. This improves the borehole formation capacity and gas extraction effect of pneumatic directional drilling under water-bearing, fractured, and soft coal seam conditions.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A double-walled drilling tool for pneumatic directional drilling of water-bearing, soft coal seams in underground coal mines includes a double-walled water-cooled section, a double-walled drill rod, a double-walled non-magnetic drill rod, a double-walled jetting sub, a pneumatic screw drill tool, and a drill bit connected in sequence to form a dual channel for high-pressure gas, jetting slurry, and water accumulation in the borehole. The inner tubes of the double-walled water pipe, double-walled drill rod, double-walled non-magnetic drill rod, and double-walled jetting short section, as well as the pneumatic screw drill tool and drill bit, are connected in sequence to form a central channel so that high-pressure gas can enter to drive the pneumatic screw drill tool to work and drive the drill bit to rotate to break rocks and remove slag. The outer pipes of the double-wall water pipe, double-wall drill pipe, double-wall non-magnetic drill pipe and double-wall jetting and pumping short section are sequentially connected to form an outer annular passage, and a forward nozzle and a reverse suction nozzle are installed on the outer pipe of the double-wall jetting and pumping short section; the jetting slurry entering the outer annular passage from the forward direction is sprayed through the forward nozzle and adheres to the wall of the borehole; the water accumulated in the borehole is discharged out of the borehole through the reverse suction nozzle.

[0005] The application also comprises the following technical features: Specifically, the inner pipes of the double-wall water pipe, double-wall drill pipe, double-wall non-magnetic drill pipe and double-wall jetting and pumping short section are connected by plug-in connection; the outer pipes of the double-wall water pipe, double-wall drill pipe, double-wall non-magnetic drill pipe and double-wall jetting and pumping short section, the pneumatic screw drill and the drill bit are connected by screw thread connection. The central passage is connected with an air compressor or a nitrogen generator, and the outer annular passage is connected with a jetting pump or a high negative pressure extraction pipeline.

[0006] Specifically, the double-wall water pipe comprises a water pipe inner pipe, a water pipe outer pipe, a double-wall water pipe inner passage in the water pipe inner pipe and a double-wall water pipe outer annular passage between the water pipe inner pipe and the water pipe outer pipe, and a bearing assembly is installed between the water pipe inner pipe and the water pipe outer pipe.

[0007] Specifically, the double-wall drill pipe comprises a drill pipe inner pipe, male and female threaded end drill pipe inner pipe joints at both ends of the drill pipe inner pipe, a drill pipe outer pipe and male and female threaded end drill pipe outer pipe joints at both ends of the drill pipe outer pipe.

[0008] Specifically, the double-wall non-magnetic drill pipe comprises a non-magnetic drill pipe outer pipe, male and female threaded end non-magnetic drill pipe outer pipe joints at both ends of the non-magnetic drill pipe outer pipe, a non-magnetic drill pipe inner pipe and male and female threaded end non-magnetic drill pipe inner pipe joints at both ends of the non-magnetic drill pipe inner pipe, and a measuring instrument string is installed in the non-magnetic drill pipe inner pipe.

[0009] Specifically, the double-wall jetting and pumping short section comprises a jetting and pumping short section outer pipe, female and male threaded end jetting and pumping short section outer pipe joints at both ends of the jetting and pumping short section outer pipe, a jetting and pumping short section inner pipe and female and male threaded end jetting and pumping short section inner pipe joints at both ends of the jetting and pumping short section inner pipe, a forward nozzle and a reverse suction nozzle are arranged on the jetting and pumping short section outer pipe, and a positioning support sealing ring is arranged between the male threaded end jetting and pumping short section outer pipe joint and the male threaded end jetting and pumping short section inner pipe joint.

[0010] Specifically, the pneumatic screw drill comprises a motor assembly, a universal shaft assembly and a transmission shaft assembly.

[0011] Specifically, the forward nozzle and the reverse suction nozzle are installed on the jetting and pumping short section outer pipe at equal intervals. The forward nozzle comprises a forward nozzle filter screen, a forward nozzle, a forward nozzle spring, a forward nozzle body, and a forward nozzle steel ball; the forward nozzle body is installed in a through hole on the outer pipe of the jetting and pumping short section; two limiting rings are arranged in the inner passage of the forward nozzle body, the forward nozzle spring and the forward nozzle steel ball are arranged between the two limiting rings, the forward nozzle steel ball is close to the inner limiting ring, and the diameter of the forward nozzle steel ball is greater than the inner diameter of the limiting ring; and the forward nozzle filter screen is installed at the outer opening of the passage of the forward nozzle body. The reverse suction nozzle comprises a reverse suction nozzle filter screen, a reverse suction nozzle, a reverse suction nozzle steel ball, a reverse suction nozzle body, and a reverse suction nozzle spring; the reverse suction nozzle body is installed in a through hole on the outer pipe of the jetting and pumping short section; two limiting rings are arranged in the inner passage of the reverse suction nozzle body, the reverse suction nozzle spring and the reverse suction nozzle steel ball are arranged between the two limiting rings, the reverse suction nozzle steel ball is close to the outer limiting ring, and the diameter of the reverse suction nozzle steel ball is greater than the inner diameter of the limiting ring; and the reverse suction nozzle filter screen is installed at the outer opening of the passage of the reverse suction nozzle body.

[0012] A method for drilling by using the double-wall drilling tool for pneumatic directional drilling of soft coal seam with water in a coal mine, which adopts the double-wall drilling tool to normally drill and jet grout to protect the wall, and comprises the following steps. Step a1: sequentially connect the double-wall water channel, the double-wall drill rod, the double-wall non-magnetic drill rod, the double-wall jetting and pumping short section, the pneumatic screw drill and the drill bit; Step a2: connect the inner passage of the double-wall water channel with the air supply pipeline of the air compressor or the nitrogen generator, and connect the outer annular passage of the double-wall water channel with the grouting pump; Step a3: add one drill rod, start the air compressor or the nitrogen generator, supply high-pressure air or nitrogen through the central passage of the drill tool, drive the pneumatic screw drill to work and drive the drill bit to rotate to drill the rock; Step a4: when one drill rod is drilled, stop the air compressor or the nitrogen generator, start the grouting pump, supply grouting slurry through the outer annular passage of the drill tool, and jet and cover the grouting slurry around the wall of the drilled hole at high speed; wherein, during normal drilling, the forward nozzle steel ball blocks the feeding port of the forward nozzle under the elongation of the forward nozzle spring; during grouting, the high-pressure slurry acts on the forward nozzle steel ball, the forward nozzle spring is in a compressed state, the forward nozzle steel ball releases the feeding port of the forward nozzle, and the slurry enters the hole to jet and protect the wall; the forward nozzle filter screen can prevent the coal cinder from blocking the nozzle; Step a5: slowly rotate the drill tool and slowly withdraw the drill rod, to jet and protect the wall of the corresponding section of the drilled hole; Step 6: repeat steps a3-a5 to complete the drilling and grouting to protect the wall of the drilled hole.

[0013] A method for drilling by using the double-wall drilling tool for pneumatic directional drilling of soft coal seam with water in a coal mine, which adopts the double-wall drilling tool to pump out the accumulated water in the hole, and comprises the following steps: Step b1: sequentially connect double-wall water, double-wall drill pipe, double-wall non-magnetic drill pipe, double-wall jetting and pumping short section, pneumatic screw rod drilling tool and drill bit; Step b2: by pulling the drilling tool forward and backward, the double-wall jetting and pumping short section is placed in the hole water accumulation hole section; Step b3: the double-wall water outside annular channel is connected with the pumping high negative pressure pipeline; Step b4: open the pumping high negative pressure, use the vacuum negative pressure, through the drilling tool outside annular channel to the reverse suction nozzle to suck the hole water accumulation, and the hole water accumulation is discharged outside the hole through the outside annular channel; wherein, in the normal drilling process, the reverse suction nozzle steel ball blocks the reverse suction nozzle under the elongation elastic force of the reverse suction nozzle spring; in the water drainage process, under the action of the pumping high negative pressure, the outside annular channel is in a vacuum negative pressure state, at this time, the reverse suction nozzle spring is in a compressed state, the reverse suction nozzle steel ball releases the reverse suction nozzle, the hole water accumulation is sucked into the outside annular channel by the negative pressure and discharged outside the hole; the reverse suction nozzle filter screen can prevent the coal cinder from blocking the suction nozzle.

[0014] Compared with the prior art, the present application has the following technical effects: The present application adopts double-wall drilling tools to form double-medium flow channels, realizes jet grouting wall protection during pneumatic directional drilling in the condition of water-containing and soft coal seam, part of the slurry penetrates into the hole wall microcracks to play a role in consolidating and reinforcing the hole wall, and the other part can form a certain thickness of the wall protection layer around the hole wall to achieve the role of supporting the hole wall stability. In addition, the present application can realize reverse pumping of hole water accumulation, uses the coal mine underground pumping high negative pressure, forms double channels through the double-wall drill pipe, and realizes reverse pumping of hole water accumulation to solve the problem of water hole forming difficulty of pneumatic directional drilling. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a double-wall drilling tool structure schematic diagram for pneumatic directional drilling in coal mine of the present application; Figure 2 is a double-wall water structure schematic diagram of the present application; Figure 3 is a double-wall drill pipe structure schematic diagram of the present application; Figure 4 is a double-wall non-magnetic drill pipe structure schematic diagram of the present application; Figure 5 is a double-wall jetting and pumping short section structure schematic diagram of the present application; Figure 6 is a pneumatic screw rod drilling tool and drill bit structure schematic diagram of the present application; Figure 7 is a forward nozzle structure schematic diagram of the present application; Figure 8 is a reverse suction nozzle structure schematic diagram of the present application.

[0016] The meanings of the labels in the diagram are as follows: 1-Double-walled water pipe; 2-Double-walled drill pipe; 3-Double-walled non-magnetic drill pipe; 4-Double-walled injection sub; 5-Pneumatic screw drill bit; 6-Drill bit; 7-Nitrogen generator; 8-Grouting pump; 9-High negative pressure extraction pipeline; 1-1-Water pipe inner tube; 1-2-Water pipe outer tube; 1-3-Bearing assembly; 1-4-Double-walled water pipe outer annular channel; 1-5-Double-walled water pipe inner channel; 2-1-Female threaded drill pipe outer tube connector; 2-2-Female threaded... 2-3-Drill rod outer tube, 2-4-Drill rod inner tube, 2-5-Male thread end drill rod outer tube connector, 2-6-Male thread end drill rod inner tube connector; 3-1-Female thread end non-magnetic drill rod outer tube connector, 3-2-Female thread end non-magnetic drill rod inner tube connector, 3-3-Non-magnetic drill rod outer tube, 3-4-Non-magnetic drill rod inner tube, 3-5-Male thread end non-magnetic drill rod outer tube connector, 3-6-Male thread end non-magnetic drill rod inner tube connector, 3 -7- Measuring instrument string; 4-1- Female thread end spray extraction short section outer tube connector, 4-2- Female thread end spray extraction short section inner tube connector, 4-3- Spray extraction short section outer tube, 4-4- Spray extraction short section inner tube, 4-5- Male thread end spray extraction short section outer tube connector, 4-6- Male thread end spray extraction short section inner tube connector, 4-7- Forward nozzle, 4-8- Reverse suction nozzle, 4-9- Positioning support sealing ring; 5-1- Motor assembly, 5-2- Universal shaft Assembly, 5-3-Drive shaft assembly; 4-7-1-Forward nozzle filter, 4-7-2-Forward nozzle, 4-7-3-Forward nozzle spring, 4-7-4-Forward nozzle body, 4-7-5-Forward nozzle steel ball; 4-8-1-Reverse suction nozzle filter, 4-8-2-Reverse suction nozzle, 4-8-3-Reverse suction nozzle steel ball, 4-8-4-Reverse suction nozzle body, 4-8-5-Reverse suction nozzle spring. Detailed Implementation

[0017] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0018] Example: like Figures 1 to 8 As shown, this embodiment provides a double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines. It includes a double-walled water pipe 1, a double-walled drill rod 2, a double-walled non-magnetic drill rod 3, a double-walled jetting sub 4, a pneumatic screw drill bit 5, and a drill bit 6 connected in sequence to form a dual channel for high-pressure gas, jetting slurry, and water accumulation in the borehole.

[0019] The inner tubes of the double-walled water-cooled drill pipe 1, double-walled drill rod 2, double-walled non-magnetic drill rod 3, and double-walled jetting short section 4, the pneumatic screw drill tool 5, and the drill bit 6 are connected in sequence to form a central channel so that high-pressure gas can enter and drive the pneumatic screw drill tool 5 to work and drive the drill bit 6 to rotate to break rocks and remove slag.

[0020] The outer pipes of the double-wall water truck 1, the double-wall drill rod 2, the double-wall non-magnetic drill rod 3 and the double-wall jetting and pumping short section 4 are sequentially connected to form an outer annular passage, and a forward jetting nozzle 4-7 and a reverse suction nozzle 4-8 are installed on the outer pipe of the double-wall jetting and pumping short section 4; the jetting slurry entering the outer annular passage in the forward direction is jetted through the forward jetting nozzle 4-7 and adheres to the wall of the borehole; the water accumulated in the borehole is sucked into the outer annular passage through the reverse suction nozzle 4-8 and discharged outside the borehole.

[0021] The inner pipes of the double-wall water truck 1, the double-wall drill rod 2, the double-wall non-magnetic drill rod 3 and the double-wall jetting and pumping short section 4 are connected by plug-in connection; the outer pipes of the double-wall water truck 1, the double-wall drill rod 2, the double-wall non-magnetic drill rod 3, the double-wall jetting and pumping short section 4, the pneumatic screw drill 5 and the drill bit 6 are connected by screw connection.

[0022] The central passage is connected with an air compressor or a nitrogen generator 7, and is used for the high-pressure air or nitrogen to enter and drive the pneumatic screw drill 5 to work and drive the drill bit 6 to rotate to crush rocks and discharge slag, so as to realize directional drilling construction.

[0023] The outer annular passage is connected with a jetting pump 8 or a high negative pressure extraction pipeline 9, and is used for the jetting slurry to enter the borehole in the forward direction to realize jetting and wall protection of the borehole wall, or for the water accumulated in the borehole to be sucked into the outer annular passage in the reverse direction and discharged.

[0024] The double-wall water truck 1 comprises a water truck inner pipe 1-1, a water truck outer pipe 1-2, a double-wall water truck inner passage 1-5 in the water truck inner pipe 1-1 and a double-wall water truck outer annular passage 1-4 between the water truck inner pipe 1-1 and the water truck outer pipe 1-2, and a bearing assembly 1-3 is installed between the water truck inner pipe 1-1 and the water truck outer pipe 1-2.

[0025] The double-wall drill rod 2 comprises a drill rod inner pipe 2-4, a male threaded end drill rod inner pipe joint 2-6 and a female threaded end drill rod inner pipe joint 2-2 at two ends of the drill rod inner pipe 2-4, a drill rod outer pipe 2-3, a male threaded end drill rod outer pipe joint 2-5 and a female threaded end drill rod outer pipe joint 2-1 at two ends of the drill rod outer pipe 2-3.

[0026] The double-wall non-magnetic drill rod comprises a non-magnetic drill rod outer pipe 3-3, a male threaded end non-magnetic drill rod outer pipe joint 3-5 and a female threaded end non-magnetic drill rod outer pipe joint 3-1 at two ends of the non-magnetic drill rod outer pipe 3-3, a non-magnetic drill rod inner pipe 3-4, a female threaded end non-magnetic drill rod inner pipe joint 3-2 and a male threaded end non-magnetic drill rod inner pipe joint 3-6 at two ends of the non-magnetic drill rod inner pipe 3-4, and a measuring instrument string 3-7 is installed in the non-magnetic drill rod inner pipe 3-4.

[0027] The double-wall jetting and washing short section 4 comprises a jetting and washing short section outer pipe 4-3 and female threaded end jetting and washing short section outer pipe joints 4-1 and male threaded end jetting and washing short section outer pipe joints 4-5 at both ends of the jetting and washing short section outer pipe 4-3, a jetting and washing short section inner pipe 4-4 and female threaded end jetting and washing short section inner pipe joints 4-2 and male threaded end jetting and washing short section inner pipe joints 4-6 at both ends of the jetting and washing short section inner pipe 4-4, a forward nozzle 4-7 and a reverse suction nozzle 4-8 are arranged on the jetting and washing short section outer pipe 4-3, and a positioning support sealing ring 4-9 is arranged between the male threaded end jetting and washing short section outer pipe joint 4-5 and the male threaded end jetting and washing short section inner pipe joint 4-6.

[0028] The pneumatic screw drill 5 comprises a motor assembly 5-1, a universal shaft assembly 5-2 and a transmission shaft assembly 5-3.

[0029] The inner pipes of the double-wall water hose 1, the double-wall drill pipe 2, the double-wall non-magnetic drill pipe 3 and the double-wall jetting and washing short section 4, the pneumatic screw drill 5 and the drill bit 6 are sequentially connected and communicated to form a central passage, wherein the inner pipes are sequentially connected through the female threaded end inner pipe joints and the male threaded end inner pipe joints. The outer pipes of the double-wall water hose 1, the double-wall drill pipe 2, the double-wall non-magnetic drill pipe 3 and the double-wall jetting and washing short section 4 are sequentially connected to form an outer annular passage, wherein the outer pipes are sequentially connected through the female threaded end outer pipe joints and the male threaded end outer pipe joints.

[0030] The forward nozzle 4-7 and the reverse suction nozzle 4-8 are installed at equal intervals on the jetting and washing short section outer pipe 4-3 and are connected to the jetting and washing short section outer pipe 4-3 through threads, and can be replaced.

[0031] The forward nozzle 4-7 comprises a forward nozzle filter screen 4-7-1, a forward nozzle 4-7-2, a forward nozzle spring 4-7-3, a forward nozzle body 4-7-4 and a forward nozzle steel ball 4-7-5. The forward nozzle body 4-7-4 is installed in a through hole on the jetting and washing short section outer pipe 4-3. Two limiting rings are arranged in the inner passage of the forward nozzle body 4-7-4, the forward nozzle spring 4-7-3 and the forward nozzle steel ball 4-7-5 are arranged between the two limiting rings, the forward nozzle steel ball 4-7-5 is close to the inner limiting ring, and the diameter of the forward nozzle steel ball 4-7-5 is greater than the inner diameter of the limiting ring. The forward nozzle filter screen 4-7-1 is installed at the outer opening of the passage of the forward nozzle body 4-7-4. More specifically, the inner passage of the forward nozzle body 4-7-4 penetrates the inner and outer pipes of the jetting and washing short section outer pipe 4-3, and the inner passage of the forward nozzle body 4-7-4 sequentially comprises an outward opening horn, an outer limiting ring, a middle passage, an inner limiting ring and an inward opening horn from outside to inside.

[0032] The reverse suction nozzle 4-8 comprises a reverse suction nozzle filter screen 4-8-1, a reverse suction nozzle 4-8-2, a reverse suction nozzle steel ball 4-8-3, a reverse suction nozzle body 4-8-4, and a reverse suction nozzle spring 4-8-5. The reverse suction nozzle body 4-8-4 is installed in a through hole on the outer pipe 4-3 of the jetting and pumping short section. Two limiting rings are arranged in the inner passage of the reverse suction nozzle body 4-8-4. The reverse suction nozzle spring 4-8-5 and the reverse suction nozzle steel ball 4-8-3 are arranged between the two limiting rings, and the reverse suction nozzle steel ball 4-8-3 is close to the limiting ring on the outer side. The diameter of the reverse suction nozzle steel ball 4-8-3 is greater than the inner diameter of the limiting ring. The reverse suction nozzle filter screen 4-8-1 is installed at the outer opening of the passage of the reverse suction nozzle body 4-8-4. More specifically, the inner passage of the reverse suction nozzle body 4-8-4 penetrates the inner and outer pipes 4-3 of the jetting and pumping short section. The inner passage of the reverse suction nozzle body 4-8-4 comprises, from the outside to the inside, an outwardly open horn, the limiting ring on the outer side, the middle part of the passage, the limiting ring on the inner side, and an inwardly open horn.

[0033] The embodiment also provides a method for drilling with the double-wall drilling tool for pneumatic directional drilling in a water-containing and soft coal seam in a coal mine, which adopts the double-wall drilling tool to normally drill and jet grout the wall, and comprises the following steps. Step a1: sequentially connect the double-wall water channel, the double-wall drill rod, the double-wall non-magnetic drill rod, the double-wall jetting and pumping short section, the pneumatic screw drill tool, and the drill bit. Step a2: connect the inner passage of the double-wall water channel with the air supply pipeline of the air compressor or the nitrogen generator, and connect the outer annular passage of the double-wall water channel with the grouting pump. Step a3: add one drill rod, start the air compressor or the nitrogen generator, supply high-pressure air or nitrogen through the central passage of the drill tool, drive the pneumatic screw drill tool to work and drive the drill bit to rotate to drill the rock. Step a4: when one drill rod is drilled, stop the air compressor or the nitrogen generator, start the grouting pump, supply grouting slurry through the outer annular passage of the drill tool, and jet and cover the grouting slurry around the wall of the borehole. During normal drilling, the steel ball of the forward nozzle is blocked by the forward nozzle spring, and during grouting, the high-pressure slurry acts on the steel ball of the forward nozzle, the forward nozzle spring is in a compressed state, the steel ball of the forward nozzle is released, the slurry enters the borehole to jet and protect the wall, and the forward nozzle filter screen can prevent coal cinder from blocking the nozzle. Step a5: slowly rotate the drill tool and slowly withdraw the drill rod to jet and protect the wall of the borehole around the corresponding section. Step 6: repeat steps a3-a5 to complete the drilling and grouting of the borehole.

[0034] The embodiment also provides a method for drilling with the double-wall drilling tool for pneumatic directional drilling in a water-containing and soft coal seam in a coal mine, which adopts the double-wall drilling tool to pump out the accumulated water in the borehole, and comprises the following steps. Step b1: sequentially connect double-wall water, double-wall drill pipe, double-wall non-magnetic drill pipe, double-wall jet pump short section, pneumatic screw rod drill and drill bit; Step b2: place the double-wall jet pump short section in the hole water hole section by pulling the drill forward and backward; Step b3: connect the double-wall water outside annular channel with the extraction high negative pressure pipeline; Step b4: open the extraction high negative pressure, use vacuum negative pressure, pass through the drill outside annular channel to reach the reverse suction nozzle to suck the hole water, and discharge the hole water outside the hole through the outside annular channel; during normal drilling, the reverse suction nozzle steel ball blocks the reverse suction nozzle under the elongation elastic force of the reverse suction nozzle spring; during the drainage process, under the action of the extraction high negative pressure, the outside annular channel is in a vacuum negative pressure state, at this time the reverse suction nozzle spring is in a compressed state, the reverse suction nozzle steel ball releases the reverse suction nozzle, the hole water is sucked into the outside annular channel by the negative pressure and discharged outside the hole; the reverse suction nozzle filter screen can prevent the coal cinder from blocking the suction nozzle; The preferred embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0035] In addition, it should be noted that various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again by the present application.

[0036] In addition, various different embodiments of the present application can also be combined in any appropriate manner, as long as it does not deviate from the technical concept of the present application, and it should be considered as disclosed by the present application.

Claims

1. A double-walled drill bit for pneumatic directional drilling in soft, water-bearing coal seams in underground coal mines, characterized in that, It includes a double-walled water pipe (1), a double-walled drill pipe (2), a double-walled non-magnetic drill pipe (3), a double-walled jetting sub (4), a pneumatic screw drill (5), and a drill bit (6) connected in sequence to form a double channel for high-pressure gas, jetting slurry, and water accumulation in the hole to pass through; The inner tubes of the double-walled water pipe (1), double-walled drill rod (2), double-walled non-magnetic drill rod (3), and double-walled jetting short section (4), the pneumatic screw drill tool (5), and the drill bit (6) are connected in sequence to form a central channel so that high-pressure gas can enter and drive the pneumatic screw drill tool (5) to work and drive the drill bit (6) to rotate to crush rock and discharge slag. The outer tubes of the double-walled water pipe (1), double-walled drill rod (2), double-walled non-magnetic drill rod (3), and double-walled spraying short section (4) are connected in sequence to form an outer annular channel. A forward nozzle (4-7) and a reverse suction nozzle (4-8) are installed on the outer tube of the double-walled spraying short section (4). The sprayed slurry entering the outer annular channel in the forward direction is sprayed through the forward nozzle (4-7) and adheres to the borehole wall. The water accumulated in the hole enters the outer annular channel through the reverse suction nozzle (4-8) and is discharged outside the hole.

2. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The inner tubes of the double-walled water pipe (1), double-walled drill rod (2), double-walled non-magnetic drill rod (3), and double-walled jetting short section (4) are connected by plug-in joints; the outer tubes of the double-walled water pipe (1), double-walled drill rod (2), double-walled non-magnetic drill rod (3), and double-walled jetting short section (4), the pneumatic screw drill tool (5), and the drill bit (6) are connected by threaded joints. The central channel is connected to an air compressor or nitrogen generator (7); the outer annular channel is connected to a grouting pump (8) or a high negative pressure extraction pipeline (9).

3. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The double-walled toilet (1) includes an inner toilet pipe (1-1) and an outer toilet pipe (1-2) arranged from the inside to the outside, a double-walled toilet inner channel (1-5) inside the inner toilet pipe (1-1), and a double-walled toilet outer annular channel (1-4) between the inner toilet pipe (1-1) and the outer toilet pipe (1-2). A bearing assembly (1-3) is installed between the inner toilet pipe (1-1) and the outer toilet pipe (1-2).

4. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The double-walled drill pipe (2) includes an inner tube (2-4) and its two ends, a male-end drill pipe inner tube joint (2-6) and a female-end drill pipe inner tube joint (2-2), an outer tube (2-3) and its two ends, a male-end drill pipe outer tube joint (2-5) and a female-end drill pipe outer tube joint (2-1).

5. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The double-walled non-magnetic drill rod includes a non-magnetic drill rod outer tube (3-3) and its two ends, a male non-magnetic drill rod outer tube connector (3-5) and a female non-magnetic drill rod outer tube connector (3-1), a non-magnetic drill rod inner tube (3-4) and its two ends, a female non-magnetic drill rod inner tube connector (3-2) and a male non-magnetic drill rod inner tube connector (3-6), and a measuring instrument string (3-7) is installed inside the non-magnetic drill rod inner tube (3-4).

6. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The double-walled spray extraction short section (4) includes an outer tube (4-3) and two female-end spray extraction short section outer tube connectors (4-1) and male-end spray extraction short section outer tube connectors (4-5) at both ends, an inner tube (4-4) and two female-end spray extraction short section inner tube connectors (4-2) and male-end spray extraction short section inner tube connectors (4-6) at both ends. A forward nozzle (4-7) and a reverse suction nozzle (4-8) are provided on the outer tube (4-3), and a positioning support sealing ring (4-9) is provided between the male-end spray extraction short section outer tube connector (4-5) and the male-end spray extraction short section inner tube connector (4-6).

7. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 1, characterized in that, The pneumatic screw drill (5) includes a motor assembly (5-1), a universal joint assembly (5-2), and a drive shaft assembly (5-3).

8. The double-walled drill bit for pneumatic directional drilling of soft, water-bearing coal seams in underground coal mines as described in claim 6, characterized in that, The forward nozzle (4-7) and the reverse suction nozzle (4-8) are installed at equal intervals on the outer tube (4-3) of the spray and suction section. The forward nozzle (4-7) includes a forward nozzle filter (4-7-1), a forward nozzle (4-7-2), a forward nozzle spring (4-7-3), a forward nozzle body (4-7-4), and a forward nozzle steel ball (4-7-5). The forward nozzle body (4-7-4) is installed in a through hole on the outer tube (4-3) of the spray extraction section. Two limiting rings are provided in the inner channel of the forward nozzle body (4-7-4). The forward nozzle spring (4-7-3) and the forward nozzle steel ball (4-7-5) are located between the two limiting rings, with the forward nozzle steel ball (4-7-5) closer to the inner limiting ring. The diameter of the forward nozzle steel ball (4-7-5) is larger than the inner diameter of the limiting ring. The forward nozzle filter (4-7-1) is installed at the outer opening of the channel of the forward nozzle body (4-7-4). The reverse suction nozzle (4-8) includes a reverse suction nozzle filter (4-8-1), a reverse suction nozzle (4-8-2), a reverse suction nozzle steel ball (4-8-3), a reverse suction nozzle body (4-8-4), and a reverse suction nozzle spring (4-8-5). The reverse suction nozzle body (4-8-4) is installed in a through hole on the outer tube (4-3) of the spray extraction short section. Two limiting rings are provided in the inner channel of the reverse suction nozzle body (4-8-4). The reverse suction nozzle spring (4-8-5) and the reverse suction nozzle steel ball (4-8-3) are located between the two limiting rings, with the reverse suction nozzle steel ball (4-8-3) closer to the outer limiting ring. The diameter of the reverse suction nozzle steel ball (4-8-3) is larger than the inner diameter of the limiting ring. The reverse suction nozzle filter (4-8-1) is installed at the outer opening of the channel of the reverse suction nozzle body (4-8-4).

9. A method for drilling using a double-walled pneumatic directional drilling tool for soft, water-bearing coal seams in underground coal mines as described in any one of claims 1 to 8, characterized in that, This method uses a double-walled drilling tool, involves normal drilling and shotcrete wall protection, and includes the following steps: Step a1: Connect the double-walled water pipe, double-walled drill pipe, double-walled non-magnetic drill pipe, double-walled jetting sub, pneumatic screw drill bit and drill bit in sequence; Step a2: Connect the inner channel of the double-walled water pipe to the air compressor or nitrogen generator supply line, and connect the outer annular channel of the double-walled water pipe to the grouting pump; Step a3: Add one drill rod, start the air compressor or nitrogen generator, supply high-pressure air or nitrogen through the central channel of the drill bit, drive the pneumatic screw drill bit to work and drive the drill bit to rotate to break the rock and drill. Step a4: When drilling one drill rod is completed, turn off the air compressor or nitrogen generator, start the grouting pump, and supply grouting slurry through the outer annular channel of the drill string. The grouting slurry is sprayed out at high speed through the forward nozzle, spraying and covering the borehole wall. During normal drilling, the forward nozzle steel ball blocks the forward nozzle inlet under the extension force of the forward nozzle spring. During grouting, the high-pressure slurry acts on the forward nozzle steel ball, the forward nozzle spring is in a compressed state, and the forward nozzle steel ball releases the forward nozzle inlet, allowing the slurry to enter the hole for grouting and wall protection. The forward nozzle filter screen can prevent coal slag from clogging the nozzle. Step a5: Slowly rotate the drill bit and slowly withdraw the drill rod to complete the slurry spraying around the borehole wall of the corresponding section; Step 6: Repeat steps a3-a5 to complete the drilling and shotcrete wall protection.

10. A method for drilling in underground water-bearing, fractured, soft coal seams using a double-walled pneumatic directional drilling tool as described in any one of claims 1 to 8, characterized in that, This method uses a double-walled drill bit to pump out water accumulated in the borehole, and includes the following steps: Step b1: Connect the double-walled water pipe, double-walled drill pipe, double-walled non-magnetic drill pipe, double-walled jetting sub, pneumatic screw drill bit and drill bit in sequence; Step b2: By pulling the drill string back and forth, place the double-walled jet pumping sub into the water accumulation section of the hole; Step b3: Connect the double-walled water-purifying outer annular channel to the high negative pressure extraction pipeline; Step b4: Activate the high negative pressure extraction system. Utilize the vacuum negative pressure to draw water from the hole through the outer annular channel of the drill bit to the reverse suction nozzle. The water is then discharged from the hole through the outer annular channel. During normal drilling, the reverse suction nozzle steel ball blocks the reverse suction nozzle under the extension force of the reverse suction nozzle spring. During drainage, under the high negative pressure extraction system, the outer annular channel is under vacuum negative pressure. At this time, the reverse suction nozzle spring is compressed, and the reverse suction nozzle steel ball releases the reverse suction nozzle. The water in the hole is drawn into the outer annular channel by the negative pressure and discharged from the hole. The reverse suction nozzle filter screen prevents coal slag from clogging the suction nozzle.

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