Gas-containing coal sample deep hole pressure maintaining drilling device and method

Abstract

The invention belongs to the technical field of coal mining, and relates to a gas-containing coal sample deep hole pressure maintaining drilling device and method.The device comprises a first outer pipe, a coring inner pipe and a sampling drill bit; a cut-off ball valve is arranged at the front end of the coring inner pipe, the upper end and the lower end of the cut-off ball valve are each provided with a gear, and the gears rotate to drive the cut-off ball valve to rotate so as to control the cut-off ball valve to be opened and closed. The front end of the first outer pipe is provided with square holes which are symmetrical up and down and are matched with the gears, the rear ends of the square holes are provided with racks, the racks are meshed with the gears of the cut-off ball valve, and the gears are driven to rotate through rotation of the first outer pipe so as to control opening and closing of the cut-off ball valve; the sampling drill bit is connected with the coring inner pipe, and the coring inner pipe is rotationally connected with the first outer pipe. Opening and closing of the cut-off ball valve are controlled through forward and reverse torque directly provided by the drilling machine, and in-situ pressure maintaining sealing of the coal sample is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coal mining, and relates to a deep-hole pressure-maintaining drilling device and method for a gas-containing coal sample. BACKGROUND

[0002] Gas accidents are one of the most serious types of accidents in the production of coal mines in China, and therefore gas extraction work has become a key link in the management of high-gas mines. In the whole process of gas extraction, the accurate determination of the gas content of the coal seam is always involved. Before extraction, by determining the original gas content, the gas enrichment degree of different regions can be differentiated: high-content regions need to be arranged with more drilling holes, and low-content regions can appropriately increase the drilling hole spacing. During the extraction process, the gas content needs to be determined in a timely manner to evaluate the extraction effect; after the extraction reaches the standard, the residual gas content needs to be determined to provide a basis for the ventilation design in subsequent tunneling and mining work. At present, the detection of the gas content usually adopts the desorption method: the coal core taken out of the drilling hole is immediately loaded into a sealed tank or a sealed core, and then part of the coal sample is used to determine the gas desorption amount by using a desorption instrument, and the change rule of the gas desorption amount with time is analyzed. However, with the increase of the drilling hole depth, the coal sample taken out of the hole is easy to cause gas to escape during the lifting process, resulting in distorted measurement results. Therefore, it is urgent to develop a deep-hole in-situ pressure-maintaining sampling technology and device to avoid the loss of gas caused by the contact of the coal sample with the atmosphere during the sampling process.

[0003] In view of the above problems, the prior art proposes a "coal mine deep-hole fixed-point sealed sampling device and method" as disclosed in patent No. CN202211152754.X. The scheme realizes the opening and closing of the valve by ball throwing or water pressure driving to drill the coal sample. However, this method still has obvious defects in actual application: first, when high-pressure water is used as the power medium, the water flow is easy to enter the coal sample, which interferes with the gas analysis process, resulting in a decrease in the accuracy of the measurement results; second, the device relies on a high-pressure water pump to provide opening and closing power, and needs to be matched with a water supply pipeline, a water tank, a high-pressure pump, a high-pressure rubber pipe and a valve group and other auxiliary equipment, which not only increases the system complexity, but also increases the requirements for the sealing pressure-bearing capacity of the drilling rod. Specifically, the existing deep-hole fixed-point sealed sampling device mostly uses a high-pressure mud pump to provide sealing power. Before starting sampling, a high-pressure pump needs to be used to pump high-pressure water into the drilling rod, and after the water pressure is increased, the drive pipe pushes the front valve core to open; after the coal sample is filled, the high-pressure pump needs to be connected again to inject high-pressure water to close the valve core. The whole operation process is complicated, and it is difficult to operate in the underground environment. More seriously, the high-pressure water may seep into the ball valve position through the piston hole at the rear end of the coring pipe during the pushing process. If the ball valve has not been completely closed, the water flow will enter the inside of the coring pipe, directly soaking the coal sample, so that the coal sample loses its representativeness, resulting in invalid gas content measurement results.

[0004] In summary, the prior art has two major shortcomings: one is to rely on high-pressure hydraulic system to realize the sealing of the coring tube, the operation process is complex, and the construction efficiency is low; the second is that high-pressure water is easy to cause pollution to the coal sample, which affects the accuracy of the gas analysis data. Therefore, there is an urgent need for a new deep hole in-situ sampling scheme with simplified structure, convenient operation and effective prevention of water medium pollution. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a deep hole pressure maintaining drilling device and method for gas-containing coal samples to solve the problems in the background art.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: A deep hole pressure maintaining drilling device for gas-containing coal samples, comprising a first outer tube, a coring inner tube and a sampling drill bit; The front end of the coring inner tube is provided with a shut-off ball valve, and the upper and lower ends of the shut-off ball valve are each provided with a gear, the rotation of the gear drives the rotation of the shut-off ball valve to control its opening and closing; The front end of the first outer tube is provided with a symmetrical square hole, and the square hole is matched with the gear, the rear end of the square hole is provided with a rack, and the rack is engaged with the gear of the shut-off ball valve, the rotation of the first outer tube drives the rotation of the gear to control the opening and closing of the shut-off ball valve; The sampling drill bit is connected with the coring inner tube, and the coring inner tube is rotationally connected with the first outer tube.

[0007] Further, bearings are arranged at the front, middle and rear parts of the coring inner tube, the bearings are closely matched with the first outer tube to limit the axial movement between the coring inner tube and the first outer tube, and allow the relative rotation between the coring inner tube and the first outer tube.

[0008] Further, a rear inner joint, a screw and a rubber plug are arranged at the rear end of the coring inner tube, the rear inner joint is threadedly connected at the rear end of the coring inner tube, the rubber plug is axially inserted on the rear inner joint, and the screw is radially installed on the rear inner joint to limit the axial displacement of the rubber plug.

[0009] Further, the rear end of the first outer tube is connected with a drill rod through a thread, the front end of the drill rod is provided with two rebound pins on both sides, the rebound pins can be extended and retracted by pressing, and the rear end of the first outer tube is provided with a groove matched with the rebound pins, so that when the drill rod and the first outer tube are tightened, the rebound pins can be extended into the groove. The rebound pin and the groove constitute a drill rod anti-disengagement device to prevent the drill rod from disengaging from the first outer tube when a reverse torque is applied.

[0010] Further, the rear end of the drill rod is also provided with the groove, so that the locking is realized through the rebound pin and the groove when the adjacent two drill rods are screwed to each other.

[0011] Further, the cut-off ball valve is opened by the forward torque provided by the drilling machine and is closed by the reverse torque, so that the sealing of the coring inner tube is realized without using high-pressure hydraulic drive.

[0012] Further, the front end of the coring inner tube is also provided with a threaded joint, the cut-off ball valve is arranged on the threaded joint, and the sampling drill bit is connected with the coring inner tube through the threaded joint.

[0013] Further, the front and rear ends of the cut-off ball valve are respectively provided with front and rear sealing pads.

[0014] Further, the second outer tube is rotatably sleeved at the front end of the coring inner tube and is threadedly connected with the first outer tube and movably connected with the sampling drill bit.

[0015] Further, the rubber plug is used for sealing the rear end of the coring inner tube, preventing gas leakage, and allowing the internal gas to be extracted through the injection needle.

[0016] Further, the dust cover is detachably connected on the square hole.

[0017] In another aspect, the application also provides a deep hole pressure-maintaining drilling method for a gas-containing coal sample, which uses the deep hole pressure-maintaining drilling device for the gas-containing coal sample, and specifically includes the following steps: After the drilling is completed, the deep hole pressure-maintaining drilling device for the gas-containing coal sample and the drill rod with the rebound pin are loaded into the drilling machine, at this time, the cut-off ball valve in the deep hole pressure-maintaining drilling device for the gas-containing coal sample is in a closed state; When the sampling point is reached, the drilling machine applies a forward torque to the drill rod and the first outer tube, drives the gear to rotate through the rack, and rotates the cut-off ball valve to open; The torque is continuously increased to drive the sampling drill bit to rotate and drill for sampling; When the coal sample is filled in the coring inner tube, the forward torque is stopped, the reverse torque is applied, the gear is reversely rotated to close the cut-off ball valve through the rack, the sealing of the coring inner tube is realized, and the deep hole pressure-maintaining drilling for the gas-containing coal sample is completed.

[0018] Further, after the deep hole pressure-maintaining drilling device for the gas-containing coal sample is taken out, the internal gas in the coring inner tube is extracted through the rubber plug at the rear end of the coring inner tube for inspection.

[0019] Further, after the deep hole pressure-maintaining drilling device for the gas-containing coal sample is taken out, the coal sample can be taken out through the rear inner joint at the rear end of the coring inner tube for further inspection. Further, the rear end of the drill rod is also provided with the groove, so that the locking is realized through the rebound pin and the groove when the adjacent two drill rods are screwed to each other.

[0011] Further, the cut-off ball valve is opened by the forward torque provided by the drilling machine and is closed by the reverse torque, so that the sealing of the coring inner tube is realized without using high-pressure hydraulic drive.

[0012] Further, the front end of the coring inner tube is also provided with a threaded joint, the cut-off ball valve is arranged on the threaded joint, and the sampling drill bit is connected with the coring inner tube through the threaded joint.

[0013] Further, the front and rear ends of the cut-off ball valve are respectively provided with front and rear sealing pads.

[0014] Further, the second outer tube is rotatably sleeved at the front end of the coring inner tube and is threadedly connected with the first outer tube and movably connected with the sampling drill bit.

[0015] Further, the rubber plug is used for sealing the rear end of the coring inner tube, preventing gas leakage, and allowing the internal gas to be extracted through the injection needle.

[0016] Further, the dust cover is detachably connected on the square hole.

[0017] In another aspect, the application also provides a deep hole pressure-maintaining drilling method for a gas-containing coal sample, which uses the deep hole pressure-maintaining drilling device for the gas-containing coal sample, and specifically includes the following steps: After the drilling is completed, the deep hole pressure-maintaining drilling device for the gas-containing coal sample and the drill rod with the rebound pin are loaded into the drilling machine, at this time, the cut-off ball valve in the deep hole pressure-maintaining drilling device for the gas-containing coal sample is in a closed state; When the sampling point is reached, the drilling machine applies a forward torque to the drill rod and the first outer tube, drives the gear to rotate through the rack, and rotates the cut-off ball valve to open; The torque is continuously increased to drive the sampling drill bit to rotate and drill for sampling; When the coal sample is filled in the coring inner tube, the forward torque is stopped, the reverse torque is applied, the gear is reversely rotated to close the cut-off ball valve through the rack, the sealing of the coring inner tube is realized, and the deep hole pressure-maintaining drilling for the gas-containing coal sample is completed.

[0018] Further, after the deep hole pressure-maintaining drilling device for the gas-containing coal sample is taken out, the internal gas in the coring inner tube is extracted through the rubber plug at the rear end of the coring inner tube for inspection.

[0019] Further, after the deep hole pressure-maintaining drilling device for the gas-containing coal sample is taken out, the coal sample can be taken out through the rear inner joint at the rear end of the coring inner tube for further inspection.

[0020] Further, when a positive torque is applied, the cut-off ball valve is opened by 90°, and when the rack reaches the limit position, the cut-off ball valve no longer rotates, and the coring inner tube and the first outer tube are locked relative to each other to transmit the positive torque of the first outer tube to the coring inner tube and the sampling drill bit.

[0021] Further, when a reverse torque is applied, the cut-off ball valve is closed by 90°, achieving pressure sealing of the coal sample.

[0022] Further, the rear end of the first outer tube is connected to the drill rod through threads, both sides of the front end of the drill rod are provided with two rebound pins, the rebound pins can be extended and retracted by pressing, and a groove matched with the rebound pins is arranged at the rear end of the first outer tube, so that when the drill rod is tightened with the first outer tube, the rebound pins can be extended into the groove. The rebound pin and the groove constitute a drill rod anti-disengagement device, which prevents the drill rod from being disengaged from the first outer tube when a reverse torque is applied.

[0023] Further, the front and rear ends of the cut-off ball valve are respectively provided with front and rear sealing pads to ensure the air tightness of the cut-off ball valve in the closed state and prevent gas from escaping.

[0024] The beneficial effects of the present application are: The present application provides a deep hole pressure maintaining and drilling device and method for coal samples containing gas, which controls the opening and closing of the cut-off ball valve by using the positive and reverse torques directly provided by the drilling machine, and achieves in-situ pressure sealing of the coal sample. The core of the scheme is to use a gear-rack transmission mechanism and bearing isolation design, so that the rotation of the drill rod outer tube is only transmitted to the valve core when the ball valve is opened and closed, and the torque is effectively transmitted to the drill bit during sampling drilling. The whole process does not need high-pressure hydraulic drive, avoiding the pollution risk of water medium to the coal sample in the traditional scheme, and significantly simplifying the equipment structure and operation process.

[0025] Compared with the prior art, the present application does not need to be equipped with high-pressure water pump, mud pump, water supply pipeline, water tank, high-pressure rubber pipe and valve group and other auxiliary equipment, which greatly reduces the system complexity and the requirement for the sealing pressure bearing capacity of the drill rod. During construction, only the positive torque of the drilling machine is needed to open the ball valve and drill for sampling, and the reverse torque is needed to close the ball valve to complete the sealing, which is simple and convenient to operate, and no water operation is needed. Not only the difficulty of underground construction and labor input are reduced, and the construction efficiency is improved by more than 50%, but also time and labor cost are saved.

[0026] In addition, since the defect of high-pressure water possibly seeping into the coring inner tube to soak the coal sample is completely avoided, the present application effectively prevents the gas escape and water pollution of the coal sample during sampling, ensures the representativeness and measurement accuracy of the gas content of the coal sample, and provides reliable technical support for accurate measurement of the gas content of high-gas mines.

[0027] Additional advantages, objects, and features of the application will be apparent to those skilled in the art upon examination of the following specification. It is intended that the application not be limited by any of the details of the specification. Instead, the true scope of the application is to be determined by the full width of the claims. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to make the objects, technical solutions and advantages of the present application clearer, the preferred embodiments of the present application will be described in detail below with reference to the drawings, in which: Figure 1 It is an external schematic view of a deep-hole pressure-maintaining drilling device for a gas-containing coal sample in an embodiment; Figure 2 It is an external schematic view of a deep-hole pressure-maintaining drilling device for a gas-containing coal sample in an embodiment (first outer tube separation); Figure 3 It is a structural schematic view of a deep-hole pressure-maintaining drilling device for a gas-containing coal sample in an embodiment; Figure 4 It is an A-A sectional view in Figure 3 ; Figure 5 It is a partial structural schematic view of a drill rod anti-disengagement device in an embodiment Figure 1 ; Figure 6 It is a partial structural schematic view of a drill rod anti-disengagement device in an embodiment Figure 2 .

[0029] Reference signs: 1 - first outer tube, 101 - square hole, 102 - rack, 103 - groove, 2 - coring inner tube, 3 - rear sealing gasket, 4 - shut-off ball valve, 401 - gear, 5 - front sealing gasket, 6 - threaded joint, 7 - rear inner joint, 8 - rubber plug, 9 - screw, 10 - sampling drill bit, 11 - bearing, 12 - drill rod, 13 - second outer tube, 14 - rebound pin. DETAILED DESCRIPTION

[0030] The present application can be implemented or applied in other different specific embodiments, and the details in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] In the drawings, only for example, the representation is a schematic diagram, not a physical diagram, and cannot be understood as a limitation of the present application; in order to better illustrate the embodiments of the present application, some components in the drawings are omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted.

[0032] 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 not to 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 for example, and cannot be understood as a limitation of the present application, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0033] Embodiment 1 Please refer to Figures 1-6 It is a kind of deep hole pressure maintaining drilling device for gas-containing coal sample, by using the positive and negative torque (torque) provided by drilling machine to open and close coring ball valve, to realize the sealing of coring inner tube, avoid using high pressure water drive to avoid coal sample pollution.

[0034] The deep hole pressure maintaining drilling device for gas-containing coal sample includes a first outer tube 1, a coring inner tube 2, a sampling drill bit 10 and a second outer tube 13. A threaded joint 6 is arranged at the front end of the coring inner tube 2, and a shut-off ball valve 4 is arranged on the threaded joint 6, and a front sealing pad 5 and a rear sealing pad 3 are arranged at the front and rear ends of the shut-off ball valve 4 respectively, to ensure the sealing of the shut-off ball valve 4, and a gear 401 is arranged at each of the upper and lower ends of the shut-off ball valve 4, and the rotation of the gear 401 drives the rotation of the shut-off ball valve 4, to control the opening and closing of the shut-off ball valve 4. A square hole 101 symmetrical about a vertical axis is formed at the front end of the first outer tube 1, and a gear rack 102 is formed at the rear end of the square hole 101, and the gear rack 102 is engaged with the two gears 401 of the shut-off ball valve 4, to drive the rotation of the gears 401 by the rotation of the first outer tube 1, to control the opening and closing of the shut-off ball valve 4. Further, a detachable dust cover (not shown in the figure) can be arranged on the square hole 101, to prevent coal cinder from falling into the first outer tube 1, and to ensure the smooth rotation of the gears 401.

[0035] The sampling drill bit 10 is connected with the coring inner tube 2 through a threaded joint 6, the second outer tube 13 is threaded with the first outer tube 1, and the second outer tube 13 is movably connected with the sampling drill bit 10.

[0036] Bearings 11 are arranged at the front, middle and rear of the coring inner tube 2, which are tightly matched with the first outer tube 1 to limit the axial movement between the coring inner tube 2 and the first outer tube 1, and isolate the rotation of the first outer tube 1 when the first outer tube 1 rotates, so that the relative rotation between the coring inner tube 2 and the first outer tube 1 can occur.

[0037] A rear inner joint 7, a screw 9 and a rubber plug 8 are arranged at the rear end of the coring inner tube 2, wherein the rear inner joint 7 is threaded at the rear end of the coring inner tube 2, the rubber plug 8 is axially inserted on the rear inner joint 7 to play a sealing role, and the screw 9 is radially installed on the rear inner joint 7 to limit the axial displacement of the rubber plug 8 and prevent the rubber plug 8 from falling off to cause gas leakage of the coal sample.

[0038] The rear end of the first outer tube 1 in the deep hole pressure maintaining drilling device for gas-containing coal sample is connected with a drill rod 12 through a thread, two rebound pins 14 are arranged at the front end of the drill rod 12, the rebound pins 14 can realize the extension and contraction state through reciprocating pressing, and a groove 103 matched with the rebound pins 14 is arranged at the rear end of the first outer tube 1, so that when the drill rod 12 and the first outer tube 1 are tightened, the rebound pins 14 can extend into the groove 103.

[0039] Correspondingly, the groove 103 is also arranged at the rear end of the drill rod 12, so that when two drill rods are tightened with each other, the rebound pins 14 and the groove 103 can also lock the reverse torque.

[0040] When the drill rod 12 and the first outer tube 1 are tightened and the two drill rods 12 are tightened with each other, the rebound pins 14 are pressed into the groove 103 at the rear end of the corresponding first outer tube 1 or drill rod 12, so that when the reverse torque is applied, the drill rods and the first outer tube 1 of the coring tool do not loosen. When it is necessary to disassemble the drill rod 12, an elongated ejector pin is inserted into the groove at the rear end of the first outer tube 1, the rebound pin 14 is pressed to the retracted state, and then the drill rod 12 and the first outer tube 1 are disassembled in the reverse direction.

[0041] Embodiment 2 Based on the embodiment 1, the embodiment provides a deep hole pressure maintaining drilling method for gas-containing coal sample, and the specific steps are as follows: After the directional drilling is finished, the drill pipe and drill bit used for directional drilling are taken out, the deep hole pressure maintaining and drilling device for the coal sample containing gas is installed on the drilling machine, and the drill pipe 12 with the rebound pin 14 is installed, at this time, the ball valve 4 is closed; When the sampling point is reached, the sampling drill bit 10 is pressed against the front end of the coal body, at this time, the drilling machine applies a positive torque to the drill pipe 12 and the first outer pipe 1, the first outer pipe 1 is rotated at this time, and the gear 401 of the cut-off valve core 4 is driven to rotate through the rack 102, so as to rotate the cut-off ball valve 4 by 90°, the coring inner pipe 2 is opened, and when the rack 401 reaches the limit position, the cut-off valve core 4 is no longer rotated; At this time, the torque of the second outer pipe 13 is increased, the sampling drill bit 10 is rotated to drill and sample; When the coal sample fills the coring inner pipe 2, the positive torque is stopped, and a reverse torque is used, at this time, the first outer pipe 1 is reversed to drive the cut-off valve core 4 to reverse by 90° to close the ball valve, and the sealing of the coring inner pipe 2 is completed; After the deep hole coring device is taken out by the drilling machine, the injection needle is used to pierce the rubber plug 8 at the rear end of the coring inner pipe to extract the internal gas for gas inspection.

[0042] The rear inner joint 7 can be opened to take out the coal sample for inspection.

[0043] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, and they should be covered in the scope of the claims of the present application.

Claims

1. A deep-hole pressure-maintaining drilling device for gas-containing coal samples, characterized in that, This includes the first outer tube, the core sampling inner tube, and the sampling drill bit; The front end of the core-taking inner tube is provided with a shut-off ball valve, and a gear is provided at each of the upper and lower ends of the shut-off ball valve. The rotation of the gear drives the shut-off ball valve to rotate, thereby controlling its opening and closing. The front end of the first outer tube has symmetrical square holes that match the gear. The rear end of the square holes has a rack that meshes with the gear of the shut-off ball valve. The rotation of the first outer tube drives the gear to rotate, thereby controlling the opening and closing of the shut-off ball valve. The sampling drill bit is connected to the inner core tube, and the inner core tube is rotatably connected to the first outer tube.

2. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, Bearings are provided at the front, middle and rear of the core-retrieving inner tube. The bearings are tightly fitted with the first outer tube to restrict axial movement between the core-retrieving inner tube and the first outer tube, and to allow relative rotation between the core-retrieving inner tube and the first outer tube.

3. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, A rear inner connector, a screw, and a rubber plug are provided at the rear end of the core-taking inner tube. The rear inner connector is threaded to the rear end of the core-taking inner tube. The rubber plug is axially inserted into the rear inner connector. The screw is radially installed on the rear inner connector to limit the axial displacement of the rubber plug.

4. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, The rear end of the first outer tube is connected to the drill rod by a thread. Two spring pins are provided on both sides of the front end of the drill rod. The spring pins can be extended and retracted by pressing. A groove matching the spring pin is provided at the rear end of the first outer tube, so that the spring pin can extend into the groove when the drill rod is tightened with the first outer tube. The spring-loaded pin and the groove constitute a drill rod anti-detachment device, which prevents the drill rod from becoming loose from the first outer tube when a reverse torque is applied.

5. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 4, characterized in that, The groove is also provided at the rear end of the drill rod so that when two adjacent drill rods are tightened together, they are locked by the spring pin and the groove.

6. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, The shut-off ball valve opens with a positive torque provided by the drilling rig and closes with a reverse torque, thereby sealing the inner tube of the coring unit without the need for high-pressure hydraulic drive.

7. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, A threaded connector is provided at the front end of the core tube, the cut-off ball valve is arranged on the threaded connector, and the sampling drill bit is connected to the core tube through the threaded connector.

8. The deep-hole pressure-maintaining drilling device for gas-containing coal samples according to claim 7, characterized in that, The shut-off ball valve is provided with a front sealing gasket and a rear sealing gasket at its front and rear ends, respectively.

9. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, It also includes a second outer tube, which is rotatably sleeved on the front end of the core-taking inner tube and threadedly connected to the first outer tube, and movably connected to the sampling drill bit.

10. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 3, characterized in that, The rubber plug is used to seal the rear end of the core sampling tube to prevent gas leakage and allow the internal gas to be extracted by puncturing with an injection needle.

11. The deep-hole pressure-maintaining drilling device for gas-bearing coal samples according to claim 1, characterized in that, A detachable dust cover is provided on the square hole.

12. A method for deep-hole pressure-maintaining drilling of gas-bearing coal samples, characterized in that, The deep-hole pressure-maintaining drilling device for gas-containing coal samples as described in any one of claims 1 to 11 specifically includes the following steps: After drilling is completed, a deep-hole pressure-maintaining drilling device for gas-containing coal samples and a drill rod with a rebound pin are installed in the drilling rig. At this time, the cut-off ball valve in the deep-hole pressure-maintaining drilling device for gas-containing coal samples is in the closed state. When the sampling point is reached, the drilling rig applies a positive torque to the drill rod and the first outer pipe, which drives the gear to rotate through the rack and pinion, thereby opening the shut-off ball valve. Continue to increase the torque to drive the sampling drill bit to rotate and drill for sampling; When the core tube is filled with coal sample, the forward torque is stopped and the reverse torque is applied. The rack drives the gear to reverse and close the shut-off ball valve, thereby sealing the core tube and completing the deep-hole pressure-maintaining drilling of gas-containing coal sample.

13. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 12, characterized in that, After removing the deep-hole pressure-maintaining drilling device for the gas-containing coal sample, the internal gas is extracted for testing by piercing the rubber plug at the rear end of the core tube.

14. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 13, characterized in that, After removing the deep-hole pressure-maintaining drilling device for gas-containing coal samples, the rear inner connector at the rear end of the rear core tube can be opened to remove the coal sample for further testing.

15. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 12, characterized in that, When a positive torque is applied, the cut-off ball valve rotates 90° to open. When the rack reaches its limit position, the cut-off ball valve stops rotating, and the inner core tube and the first outer tube rotate relative to each other and lock, so as to transmit the positive torque of the first outer tube to the inner core tube and the sampling drill bit.

16. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 12, characterized in that, When a reverse torque is applied, the shut-off ball valve reverses 90° to close, achieving pressure-holding and sealing of the coal sample.

17. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 12, characterized in that, The rear end of the first outer tube is connected to the drill rod by a thread. Two spring pins are provided on both sides of the front end of the drill rod. The spring pins can be extended and retracted by pressing. A groove matching the spring pin is provided at the rear end of the first outer tube, so that the spring pin can extend into the groove when the drill rod is tightened with the first outer tube. The spring-loaded pin and the groove constitute a drill rod anti-detachment device, which prevents the drill rod from becoming loose from the first outer tube when a reverse torque is applied.

18. The method for deep-hole pressure-maintaining drilling of gas-bearing coal samples according to claim 12, characterized in that, The shut-off ball valve is provided with a front sealing gasket and a rear sealing gasket at its front and rear ends, respectively, to ensure the airtightness of the shut-off ball valve in the closed state and prevent gas from escaping.

Images