Ejector rod driving type double-wall closed coring device and method

Abstract

According to the ejector rod driving type double-wall closed coring device and method, an upper mounting groove is formed in the upper end of a ball core, a lower mounting groove is formed in the lower end of the ball core, the lower end of an upper end rotating shaft is mounted in the upper mounting groove, and the upper end of the upper end rotating shaft penetrates through a mounting through hole and is provided with a mounting nut; the special-shaped ejector block is installed on the upper end rotating shaft and located between the installation nut and a bottom plate of the containing groove, so that the upper end rotating shaft, the ball core and the special-shaped ejector block rotate synchronously, the closed sliding block is further used for pushing the transmission ejector rod to move forwards, then the special-shaped ejector block is pushed to rotate, and the special-shaped ejector block drives the upper end rotating shaft to rotate so as to drive the ball core to rotate. The sealing of the coring inner pipe is realized, the original three-layer sealed coring structure is simplified, the overall weight of the coring device is reduced, the diameter of the center hole of the ball core is greatly increased, the coring block rate and the sampling weight are improved, and the sealing performance of the device is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of core sampling for measuring coal seam gas content. Specifically, it relates to a top rod-driven double-wall sealed core sampling device and method. Background Art

[0002] Accurate determination of coal seam gas content is a key parameter for preventing and controlling mine gas disasters and evaluating gas drainage capacity. With the continuous increase in the depth of coal resource mining, the threat of coal and gas outburst disasters in mines is becoming increasingly severe. Accurately measuring the coal seam gas content is an important technical means to evaluate whether a coal seam can be tunnelled and mined. The existing testing methods for coal seam gas content are mainly divided into two types: (1) indirect method for measuring gas content, and (2) direct method for measuring gas content. Due to the difficulty in accurately replicating the coal seam geological conditions, the results of measuring coal seam gas content by the indirect method generally have large errors. Therefore, most coal mining enterprises use the direct method to measure coal seam gas content, and directly calculate the coal seam gas content by drilling gas-containing samples, on-site desorption, and laboratory testing. The key lies in on-site sampling.

[0003] Currently, open-type core barrels are mostly used for fixed-point sampling. However, during the process of recovering the core barrel, the gas loss of the coal sample is relatively large, resulting in a large error in gas content measurement. The current sealed core sampling devices mostly adopt a three-layer tube structure. The overall device has a complex structure, a large weight, and is extremely inconvenient to install and use. In addition, a gear structure is mostly used to drive the ball core to close, with a low ball core closing rate, and still a large gas loss during the process of recovering the sampling device. Therefore, a top rod-driven double-wall sealed core sampling device and method with a simple structure, convenient operation, low production cost, and reliable sealing are needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a top rod-driven double-wall sealed core sampling device and method with a simple structure, convenient operation, low production cost, and reliable sealing. It not only greatly simplifies the structure of the sealed sampling device, reduces the weight, and simplifies the complexity of operation; but also adopts a top rod transmission method, making the sealing of the device after sampling more reliable.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A top rod-driven double-wall sealed core sampling device, comprising a core sampling outer tube, a core sampling inner tube, a sealed slider, a core sampling drill bit, a ball core, an upper end rotating shaft, a lower end rotating shaft, a special-shaped top block, a transmission top rod, a sealed slider, and a gas measuring nozzle; the core sampling outer tube includes a core sampling outer rod body and an extension rod body provided at the front end of the core sampling outer rod body. A notch groove is provided on the extension rod body. The extension rod body includes a threaded section and a smooth section. A male thread is provided on the threaded section, and a first female thread is provided inside the rear end of the core sampling outer rod body; The core sampling inner tube includes a core sampling inner rod body. A core sampling channel that penetrates through from front to back is arranged inside the core sampling inner rod body. A vertical mounting plate is arranged at the rear end of the core sampling inner rod body. The gas measuring nozzle is mounted on the mounting plate. A top rod sliding groove with an upward opening is arranged on the core sampling inner rod body in the front-back direction. The driving top rod is mounted in the top rod sliding groove. The front end of the top rod sliding groove is provided with a placing groove with an upward opening, and an installation through hole is arranged in the placing groove. A core sampling through hole that penetrates through from front to back is arranged in the middle of the ball core. An upper mounting groove is arranged at the upper end of the ball core, and a lower mounting groove is arranged at the lower end of the ball core. The lower end of the upper end rotating shaft is mounted in the upper mounting groove. The upper end of the upper end rotating shaft passes through the installation through hole and is provided with an installation nut. The special-shaped top block is mounted on the upper end rotating shaft and is located between the installation nut and the bottom plate of the placing groove, so that the upper end rotating shaft, the ball core and the special-shaped top block rotate synchronously. The airtight slider is slidably mounted on the outside of the rear end of the core sampling outer tube. The rear end of the driving top rod is connected to the front end of the airtight slider, and the front end of the driving top rod is connected to the special-shaped top block.

[0006] An annular convex part is arranged on the inner wall of the core sampling inner rod body at the left end of the ball core. A pressing block is arranged at the right end of the core sampling inner rod body, and a front end fixing block is arranged at the right end of the pressing block. Polytetrafluoroethylene gaskets are arranged between the ball core and the pressing block and between the ball core and the annular convex part.

[0007] The core sampling drill bit includes a drill handle and a cutting edge. The cutting edge is arranged at the front end of the drill handle. An installation channel is arranged inside the drill handle, and a second female thread is arranged inside the rear end of the drill handle. The core sampling drill bit is mounted on the core sampling outer tube through the second female thread at the rear end of the drill handle and mating with a male thread.

[0008] The core sampling outer rod body is a cylinder or a prism.

[0009] Spiral grooves, spiral ribs or spiral ribs are arranged on the outer surface of the core sampling outer rod body.

[0010] A pull ring is arranged at the left end of the airtight slider.

[0011] The airtight core sampling method is implemented based on the above-mentioned top rod-driven double-wall airtight core sampling device, and includes the following steps: Includes the following steps: (1) Assemble the airtight core sampling device; (2) Install the assembled airtight core sampling device on the drill pipe of the drilling rig, and start the drilling rig to start rotary cutting for core sampling; (3) After the airtight core sampling device advances a certain distance forward, stop rotary cutting for core sampling; (4) Retract the drill and recover the airtight core sampling device to complete the core sampling work.

[0012] The specific operation process of step (1) is as follows: ① Install a polytetrafluoroethylene gasket at the front end of the annular protrusion inside the core barrel inner tube, install the ball core at the front end of the polytetrafluoroethylene gasket inside the core barrel inner tube, pass the upper end rotating shaft of the ball core through the installation through hole, connect the lower end rotating shaft of the ball core to the inner wall of the core barrel inner tube, then install a pressing block at the front end of the core barrel inner tube, and install a polytetrafluoroethylene gasket between the ball core and the pressing block. Finally, install the front fixing block on the pressing block with screws; ② Install the special-shaped top block and the installation nut on the upper end rotating shaft and make the special-shaped top block below the installation nut. Then adjust the position of the special-shaped top block so that it rotates in the placement groove; ③ Install the transmission ejector rod in the ejector rod chute, connect the front end of the transmission ejector rod to the special-shaped slider, and install a sealed slider at the rear end of the transmission ejector rod; ④ Install the core barrel inner tube inside the core barrel outer tube, and make the notch groove of the core barrel outer tube correspond above the placement groove of the core barrel inner tube; ⑤ Install the core bit on the core barrel outer tube through the second female thread and male thread to complete the assembly of the core sampling sealing device.

[0013] The specific operation process of step (2) is: install the core sampling sealing device on the drill pipe of the drill through the first female thread, and start the drill for rotary cutting; The specific operation process of step (3) is: as the sealed core sampling device advances forward, the cut coal sample enters the inside of the core sampling channel through the installation channel of the core bit and the core sampling through hole of the ball core. After the sealed core sampling device advances forward 0.5 - 3 m, stop the rotary cutting, inject high-pressure water into the drill pipe. The high-pressure water impacts the sealed slider after passing through the drill pipe, causing the sealed slider to move forward. The sealed slider pushes the transmission ejector rod forward, and then pushes the special-shaped top block to rotate. The special-shaped top block drives the upper end rotating shaft to rotate, and then drives the ball core to rotate, so that the core sampling through hole of the ball core rotates from the front-back direction to the left-right direction, and the ball core completely blocks the right end of the core sampling channel, realizing the sealing of the core sampling channel.

[0014] The specific process of step (4) is: after the sealed core sampling device is sealed, withdraw the drill, remove the sealed core sampling device from the drill pipe, then remove the core bit from the core barrel outer tube, take out the core barrel inner tube from the core barrel outer tube, connect the gas desorption instrument to the gas measuring nozzle for on-site desorption. After the on-site desorption is completed, reverse the special-shaped top block with a wrench, so that the core sampling through hole of the ball core rotates from the left-right direction to the front-back direction again, further opening the core sampling channel, pour out the coal sample inside the core barrel inner tube and put it into the coal sample, and complete the sealed core sampling work.

[0015] In the present application, an upper installation groove is provided at the upper end of the core ball, and a lower installation groove is provided at the lower end of the core ball. The lower end of the upper rotating shaft is installed in the upper installation groove, the upper end of the upper rotating shaft passes through the installation through hole and is equipped with an installation nut. The special-shaped top block is installed on the upper rotating shaft and is located between the installation nut and the bottom plate of the placement groove, so that the upper rotating shaft, the core ball and the special-shaped top block rotate synchronously. Further, the sealed slider is used to push the transmission ejector rod forward, and then push the special-shaped top block to rotate. The special-shaped top block drives the upper rotating shaft to rotate and then drives the core ball to rotate, realizing the sealing of the core-taking inner tube, simplifying the original three-layer sealed core-taking structure, not only reducing the overall weight of the core-taking device, but also greatly increasing the diameter of the core-taking through hole of the core ball, improving the core-taking block rate and the sampling weight, and improving the sealing performance of the device.

[0016] In summary, the design of the present application is scientific and the structure is reasonable. By means of the corresponding sealed core-taking structure, the complex structure of the existing three-layer core-taking pipe for realizing sealed core-taking is simplified, and the technical problems of the existing core-taking device, such as complex structure, large overall weight, high cost and poor sealing performance, are solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the sealed core-taking device of the present invention.

[0018] Figure 2 is a schematic structural diagram of the sealed core-taking device of the present invention except for the core-taking bit.

[0019] Figure 3 is Figure 2 the enlarged view of part A in

[0020] Figure 4 is Figure 2 the exploded view of

[0021] Figure 5 is a schematic structural diagram of the sealed core-taking device of the present invention except for the core-taking bit.

[0022] Figure 6 is a schematic structural diagram of the core-taking bit of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following further describes the embodiments of the present invention with reference to the drawings.

[0024] Embodiment 1 As Figures 1-6As shown in the figure, the push rod-driven double-wall sealed coring device includes a coring outer tube 1, a coring inner tube 2, a sealed slider 3, a coring bit 4, a ball core 5, an upper end rotating shaft 6, a lower end rotating shaft 7, a special-shaped top block 8, a transmission push rod 9, and a gas measuring nozzle 10; the coring outer tube 1 includes a coring outer rod body 11 and an extension rod body provided at the front end of the coring outer rod body 11. The extension rod body includes a threaded section 12 and a smooth section 13. A male thread 15 is provided on the threaded section 12, and a notch groove 14 is provided on the extension rod body. Specifically, the notch groove 14 is provided on the threaded section 12 or the smooth section 13. In this embodiment, it is preferably provided on the smooth section 13. A first female thread 16 is provided inside the rear end of the coring outer rod body 11; The coring inner tube 2 includes a coring inner rod body 17. A coring channel that penetrates through the front and rear is provided inside the coring inner rod body 17. A vertical mounting plate is provided at the rear end of the coring inner rod body 17. The gas measuring nozzle 10 is mounted on the mounting plate. A push rod sliding groove with an upward opening is provided on the coring inner rod body 17 in the front-rear direction. The transmission push rod 9 is mounted in the push rod sliding groove. A placement groove with an upward opening is provided at the front end of the push rod sliding groove, and a mounting through hole is provided in the placement groove; A coring through hole that penetrates through the front and rear is provided in the middle of the ball core 5. An upper mounting groove is provided at the upper end of the ball core 5, and a lower mounting groove is provided at the lower end of the ball core 5. The lower end of the upper end rotating shaft 6 is mounted in the upper mounting groove. The upper end of the upper end rotating shaft 6 passes through the mounting through hole and is provided with a mounting nut. The special-shaped top block 8 is mounted on the upper end rotating shaft 6 and is located between the mounting nut and the bottom plate of the placement groove, so that the upper end rotating shaft 6, the ball core 5, and the special-shaped top block 8 rotate synchronously; The sealed slider 3 is slidably mounted on the outside of the rear end of the coring outer tube 1. The rear end of the transmission push rod 9 is connected to the front end of the sealed slider 3, and the front end of the transmission push rod 9 is connected to the special-shaped top block 8.

[0025] An annular protrusion is provided on the inner wall of the coring inner rod body 17 at the left end of the ball core 5. A pressing block 18 is provided at the right end of the coring inner rod body 17. A front end fixing block 19 is provided at the right end of the pressing block 18. PTFE gaskets 20 are provided between the ball core 5 and the pressing block 18 and between the ball core 5 and the annular protrusion.

[0026] The coring bit 4 includes a drill shank 21 and a cutting edge 23. The cutting edge 23 is provided at the front end of the drill shank 21. An installation channel is provided inside the drill shank 21. A second female thread 22 is provided inside the rear end of the drill shank 21. The coring bit 4 is mounted on the coring outer tube 1 through the cooperation of the second female thread 22 at the rear end of the drill shank 21 and the male thread 15. The coring outer rod body 11 is a cylinder or a prism. A spiral groove 24, a spiral rib, or a spiral rib is provided on the outer surface of the coring outer rod body 11. As shown in the figure, in this example, the coring outer rod body 11 is a cylinder and a spiral groove 24 is provided on its outer surface. A pull ring 25 is provided at the left end of the sealed slider 3.

[0027] Embodiment 2 The closed coring method is implemented based on the above-mentioned ejector rod-driven double-wall closed coring device, and includes the following steps: including the following steps: (1) Assemble the closed coring device; (2) Install the assembled closed coring device on the drill pipe of the drill rig, and start the drill rig to start rotary coring; (3) After the closed coring device advances a certain distance forward, stop rotary coring; (4) Retract the drill and recover the closed coring device to complete the coring work.

[0028] The specific operation process of step (1) is as follows: ① Install a polytetrafluoroethylene gasket 20 at the front end of the annular protrusion inside the coring inner tube 2, install the spherical core 5 at the front end of the polytetrafluoroethylene gasket 20 inside the coring inner tube 2, make the upper end rotating shaft 6 of the spherical core 5 pass through the installation through hole, connect the lower end rotating shaft 7 of the spherical core 5 to the inner wall of the coring inner tube 2, then install a pressing block 18 at the front end of the coring inner tube 2, install a polytetrafluoroethylene gasket 20 between the spherical core 5 and the pressing block 18, and finally install the front fixing block 19 on the pressing block 18 through screws; ② Install the special-shaped ejector block 8 and the installation nut on the upper end rotating shaft 6 and make the special-shaped ejector block 8 be below the installation nut, and then adjust the position of the special-shaped ejector block 8 so that it rotates in the placement groove; ③ Install the transmission ejector rod 9 in the ejector rod chute, make the front end of the transmission ejector rod 9 connect to the special-shaped slider, and install the closed slider 3 at the rear end of the transmission ejector rod 9; ④ Install the coring inner tube 2 inside the coring outer tube 1, and make the notch groove 14 of the coring outer tube 1 correspond above the placement groove of the coring inner tube 2; ⑤ Install the coring bit 4 on the coring outer tube 1 through the second female thread 22 and the male thread 15 to complete the assembly of the coring closed device.

[0029] The specific operation process of step (2) is as follows: Install the coring closed device on the drill pipe of the drill rig through the first female thread 16, and start the drill rig for rotary cutting; The specific operation process of step (3) is as follows: As the closed coring device advances forward, the cut coal sample enters the inside of the coring channel through the installation channel of the coring bit 4 and the coring through hole of the spherical core 5. When the closed coring device advances 0.5 - 3 m forward, stop rotary cutting, inject high-pressure water into the drill pipe, the high-pressure water impacts the closed slider 3 after passing through the drill pipe, causing the closed slider 3 to move forward. The closed slider 3 pushes the transmission ejector rod 9 forward, and further pushes the special-shaped ejector block 8 to rotate. The special-shaped ejector block 8 drives the upper end rotating shaft 6 to rotate, and then drives the spherical core 5 to rotate, so that the coring through hole of the spherical core 5 rotates from the front-back direction to the left-right direction, and the spherical core 5 completely blocks the right end of the coring channel, realizing the sealing of the coring channel.

[0030] The specific process of step (4) is as follows: After the closed coring device is sealed, the drill is withdrawn. The closed coring device is removed from the drill pipe. Then, the coring bit 4 is removed from the coring outer pipe 1, the coring inner pipe 2 is taken out from the coring outer pipe 1, and the gas desorption instrument is connected to the gas measuring nozzle 10 for on-site desorption. After the on-site desorption is completed, the special-shaped top block 8 is rotated in reverse by a wrench (the notch groove 14 is correspondingly arranged above the placement groove of the coring inner pipe 2, that is, the wrench can rotate the special-shaped top block 8 through the notch groove 14), so that the coring through hole of the ball core 5 is rotated from the left-right direction to the front-back direction again, further opening the coring channel. The coal sample inside the coring inner pipe 2 is poured out and placed into the coal sample, and the closed coring work is completed.

[0031] In this application, an upper installation groove is opened at the upper end of the ball core 5, and a lower installation groove is opened at the lower end of the ball core 5. The lower end of the upper rotating shaft 6 is installed in the upper installation groove. The upper end of the upper rotating shaft 6 passes through the installation through hole and is installed with an installation nut. The special-shaped top block 8 is installed on the upper rotating shaft 6 and is located between the installation nut and the bottom plate of the placement groove, so that the upper rotating shaft 6, the ball core 5 and the special-shaped top block 8 rotate synchronously. Further, the closed slider 3 is used to push the transmission ejector rod 9 forward, and then push the special-shaped top block 8 to rotate. The special-shaped top block 8 drives the upper rotating shaft 6 to rotate and then drives the ball core 5 to rotate, realizing the sealing of the coring inner pipe 2, simplifying the original three-layer closed coring structure, and at the same time improving the sealing performance of the device.

[0032] In summary, the design of this application is scientific and the structure is reasonable. Through the corresponding closed coring structure, the complex structure of realizing closed coring with the existing three-layer coring pipe is simplified, and the technical problems of the existing coring device, such as complex structure, large overall weight, high cost and poor sealing performance, are solved.

[0033] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that; still modifications or equivalent replacements can be made to the present invention, and any modification or partial replacement without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. The mandrel driven double-walled closed coring device is characterized by: It includes a coring outer tube, a coring inner tube, a sealed slide, a coring drill bit, a ball core, an upper end rotating shaft, a lower end rotating shaft, a special-shaped top block, a transmission top rod, a sealed slide, and a gas measuring nozzle; the coring outer tube includes a coring outer rod body and an extension rod body arranged at the front end of the coring outer rod body, the extension rod body is provided with a notch groove, the extension rod body includes a threaded section and a smooth section, the threaded section is provided with a male thread, and the rear end of the coring outer rod body is provided with a first female thread; The coring inner tube comprises a coring inner rod body, a coring passage which passes through the inner rod body from front to back is arranged inside the coring inner rod body, a vertical mounting plate is arranged at the rear end of the coring inner rod body, a gas measuring nozzle is mounted on the mounting plate, a push rod slide groove which opens upward is arranged on the inner rod body in the front-to-back direction, a transmission push rod is mounted in the push rod slide groove, a placement groove which opens upward is arranged at the front end of the push rod slide groove, and a mounting through hole is arranged in the placement groove; A core-taking through hole is provided in the middle of the ball core, an upper mounting groove is provided at the upper end of the ball core, a lower mounting groove is provided at the lower end of the ball core, the lower end of the upper rotating shaft is installed in the upper mounting groove, the upper end of the upper rotating shaft passes through the mounting through hole and is installed with a mounting nut, and the special-shaped top block is installed on the upper rotating shaft and is located between the mounting nut and the bottom plate of the placement groove, so that the upper rotating shaft, the ball core and the special-shaped top block rotate synchronously; The sealed slider is slidably mounted outside the rear end of the core outer tube, the rear end of the transmission push rod is connected to the front end of the sealed slider, and the front end of the transmission push rod is connected to the special-shaped push block.

2. The mandrel-driven double-walled closed coring device according to claim 1, characterized in that: An annular protrusion is arranged on the inner wall of the coring inner rod at the left end of the spherical core, a clamping block is arranged at the right end of the coring inner rod, a front end fixing block is arranged at the right end of the clamping block, and polytetrafluoroethylene gaskets are arranged between the spherical core and the clamping block and between the spherical core and the annular protrusion.

3. The mandrel-driven double-walled closed coring device according to claim 2, characterized in that: The coring drill bit includes a drill shank and a cutting edge. The cutting edge is arranged at the front end of the drill shank. An installation channel is arranged inside the drill shank. A second female thread is arranged inside the rear end of the drill shank. The coring drill bit is installed on the coring outer tube through the cooperation of the second female thread at the rear end of the drill shank and the male thread.

4. The mandrel-driven double-walled closed coring device according to claim 3, characterized in that: The outer rod body of the coring device is a cylinder or a prism.

5. The mandrel-driven double-walled closed coring device according to claim 4, characterized in that: The outer surface of the coring outer rod body is provided with spiral grooves, spiral convex ribs or spiral ribs.

6. The mandrel-driven double-walled closed coring device according to claim 5, characterized in that: A pull ring is arranged at the left end of the sealed sliding block.

7. A closed coring method, implemented based on the mandrel driven double-walled closed coring device according to any one of claims 1 to 6, characterized in that: The steps include: (1) Assemble the closed coring device; (2) Install the assembled closed coring device on the drill pipe of the drilling rig, and start the drilling rig to start coring; (3) After the closed coring device moves forward a certain distance, the coring is stopped; (4) Withdraw the drill and retrieve the closed coring device to complete the coring work.

8. The closed coring method according to claim 7, characterized in that: The specific operation process of step (1) is as follows: ① Install a polytetrafluoroethylene gasket at the front end of the annular raised portion inside the coring inner tube, install the ball core at the front end of the polytetrafluoroethylene gasket inside the coring inner tube, make the upper end shaft of the ball core pass through the installation through hole, make the lower end shaft of the ball core connected to the inner wall of the coring inner tube, then install a clamping block at the front end of the coring inner tube, and install a polytetrafluoroethylene gasket between the ball core and the clamping block, and finally install the front end fixing block on the clamping block by screws; ② Install the special-shaped top block and the mounting nut on the upper end rotating shaft and make the special-shaped top block below the mounting nut, and then adjust the position of the special-shaped top block so that it rotates in the placement slot; ③Install the transmission push rod in the push rod slide groove, connect the front end of the transmission push rod to the special-shaped slider, and install the closed slider at the rear end of the transmission push rod; ④ Install the coring inner tube inside the coring outer tube so that the notch groove of the coring outer tube corresponds to the placement groove of the coring inner tube; ⑤ Install the coring drill bit on the coring outer tube through the second female thread and the male thread to complete the assembly of the coring sealing device.

9. The closed coring method according to claim 8, characterized in that: The specific operation process of step (2) is: installing the coring sealing device on the drill rod of the drilling rig through the first female thread, and starting the drilling rig to perform rotary cutting; The specific operation process of step (3) is as follows: as the closed coring device is advanced forward, the coal sample cut by rotary cutting passes through the installation channel of the coring drill bit and the coring hole of the ball core and enters the coring channel. When the closed coring device is advanced forward by 0.5 to 3 m, the rotary cutting is stopped and high-pressure water is injected into the drill pipe. After the high-pressure water passes through the drill pipe, it impacts the closed slider to move the closed slider forward. The closed slider pushes the transmission push rod forward, thereby pushing the special-shaped top block to rotate. The special-shaped top block drives the upper end shaft to rotate and then drives the ball core to rotate, so that the coring hole of the ball core rotates from the front-to-back direction to the left-to-right direction. The ball core completely blocks the right end of the coring channel, thereby achieving the sealing of the coring channel.

10. The closed coring method according to claim 9, characterized in that: The specific process of step (4) is as follows: after the closed coring device is sealed, the drill is withdrawn, the closed coring device is removed from the drill pipe, and then the coring drill bit is removed from the coring outer tube, the coring inner tube is taken out from the coring outer tube, and the gas desorption instrument is connected to the gas measuring nozzle for on-site desorption. After the on-site desorption is completed, the special-shaped top block is reversed by a wrench so that the coring through hole of the ball core is rotated from the left-right direction to the front-back direction again, so that the coring channel is further opened, and the coal sample inside the coring inner tube is poured out and placed in the coal sample, thereby completing the closed coring work.

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