Device and method for making ring-shaped coal briquette simulating drilling state

Abstract

The present invention discloses a device for making annular coal shapes in a simulated drilling state, which belongs to the field of coal mine safety technology. The device comprises a mold shell, a mold bottom plate, a screen tube, a support column and a pressure plate. The mold bottom plate is assembled at the lower end of the mold shell, the screen tube and the support column are assembled at the middle of the upper surface of the mold bottom plate, and the support column is inserted into the inside of the screen tube, the pressure plate is inserted into the mold shell, and the pressure plate is sleeved on the outside of the screen tube. The present invention also discloses a method for making annular coal shapes in a simulated drilling state. The present invention designs the structure of the device for making annular coal shapes, and can complete the formation of internal through holes while making coal shapes. At the same time, the device for making annular coal shapes is correspondingly designed to a simulated drilling state experimental device, so that the manufactured annular coal shapes units can be assembled and spliced ​​to form simulated drilling state experimental devices of different lengths by combining and splitting the annular coal shapes units according to specific experimental requirements, so that the simulated drilling state experiment can be more conveniently carried out.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine safety, and in particular provides a device and method for making annular coal shapes in a simulated drilling state. Background Art

[0002] At present, most of the coal molds produced under laboratory conditions are columnar coal molds, which are used for coal rock mechanics tests and gas seepage tests. When conducting sealing material bonding tests and drilling gas outburst characteristic tests that simulate coal seam drilling environments, columnar coal molds obviously cannot meet the test conditions. However, it is difficult to produce annular coal molds using traditional production methods, and it is difficult to maintain the integrity of the coal molds. The coal mold production device and the simulation experiment device are usually two sets of devices. After the annular coal molds are produced, the coal molds need to be separated from the production device, and two steps of internal demolding and external demolding are performed, and then the coal molds are transferred to the experimental device. In this process, the coal molds are easily damaged, which seriously affects the efficiency and effect of the simulated drilling test. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a device and method for making annular coal shapes in a simulated drilling state.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a device for making annular coal shapes that simulates a drilling state, including a mold shell, a mold bottom plate, a screen tube, a support column and a pressure plate, wherein the mold bottom plate is assembled at the lower end of the mold shell, the screen tube and the support column are assembled at the middle of the upper surface of the mold bottom plate, and the support column is inserted into the inside of the screen tube, the pressure plate is inserted into the mold shell, and the pressure plate is sleeved on the outside of the screen tube.

[0005] Furthermore, flanges are integrally formed at both upper and lower ends of the mold shell, a reserved hole is opened on the side surface of the mold shell, and a reserved hole baffle is installed on the reserved hole by screws.

[0006] Furthermore, a support column mounting body is integrally formed in the middle of the mold base plate, a base plate leg is fixedly mounted on the lower surface of the mold base plate, and the lower surface of the base plate leg is coplanar with the lower surface of the support column mounting body, a support column slot is provided on the upper surface of the support column mounting body, a screen tube clip is integrally formed on the upper surface of the support column mounting body, and the screen tube clip is an annular protrusion.

[0007] Furthermore, the sieve tube includes a sieve tube top, a sieve tube wall and a sieve tube bottom, wherein the sieve tube top and the sieve tube bottom are respectively arranged at the upper and lower ends of the sieve tube wall, a wide opening is provided on the lower surface of the sieve tube bottom, and the outer diameter of the sieve tube top is equal to the inner diameter of the wide opening and the outer diameter of the sieve tube clip, and a sieve hole is provided on the outer surface of the sieve tube wall.

[0008] Furthermore, the outer surface of the sieve tube wall is a rough surface, and the inner surface of the sieve tube wall is a smooth surface.

[0009] Furthermore, the support column comprises a central column and an outer wall of the support column, the central column is inserted into the outer wall of the support column, and the outer wall of the support column is inserted into the screen tube, and the central column is inserted into the support column slot;

[0010] The outer circumference of the central column is evenly fixed with inverted triangular wedges, the inner surface of the outer wall of the support column is fixed with a regular triangular wedge corresponding to the inverted triangular wedge, the outer circumference of the central column is provided with a pin groove, the inner end of the pin groove is fixed with a spring, the outer end of the spring is fixed with a triangular wedge pin inserted in the pin groove, and the triangular wedge pin is arranged between the upper and lower ends of the inverted triangular wedge, the upper surface of the central column is provided with a connecting groove located inside the central column and connected with the pin groove, the upper end of the connecting groove is plugged with a pull ring, and a pull rope is fixedly installed between the pull ring and the triangular wedge pin.

[0011] Furthermore, the outer wall of the support column is composed of two semi-cylindrical shells, a slot is provided on the end surface of one of the semi-cylindrical shells, and a plug rod matching the slot is fixedly installed on the end surface of the other semi-cylindrical shell.

[0012] Furthermore, the pressure plate includes a pressure plate ring and a pressure plate transfer rod, the outer diameter of the pressure plate ring is equal to the inner diameter of the mold shell, the pressure plate transfer rod is welded to the upper surface of the pressure plate ring, and a pressure plate reserved hole is opened in the middle of the pressure plate ring.

[0013] The method for making annular coal briquette in a simulated drilling state, using the above-mentioned device for making annular coal briquette in a simulated drilling state, specifically comprises the following steps:

[0014] Step 1: Place the mold base plate on the ground, fix the mold shell on the mold base plate through a flange, and use a reserved hole baffle to block the reserved hole on the mold shell;

[0015] Step 2: put the screen tube into the mold shell, insert the bottom of the screen tube into the screen tube clamp, insert the support column from the screen tube, insert the lower end of the central column into the support column clamping slot, and under the action of gravity, the inverted triangular wedge on the central column is located on the regular triangular wedge on the inner side of the outer wall of the support column, and then press the central column downward to squeeze the inverted triangular wedge and the regular triangular wedge against each other until the triangular wedge pin is stuck under the regular triangular wedge, so that the outer wall of the support column opens outward and is close to the inner wall of the screen tube;

[0016] Step 3: Pour coal samples into the mold shell in batches, pour 5-10 cm deep coal samples each time, flatten the coal samples, place the pressing plate on the top of the coal samples by operating the pressing plate transfer rod, and compact the coal samples. The coal samples are confined in the space formed by the mold shell, the mold bottom plate, and the pressing plate. The middle position of the coal samples is occupied by the screen tube and the support column, and the coal samples can be pressed into a ring shape to obtain a ring-shaped coal mold;

[0017] Step 4: When the space of the mold shell is completely filled and compacted by the coal sample, take out the pressing plate, lift the pull ring upward, and the pull ring drives the triangular wedge pin to move inward through the pull rope, releasing the locking relationship between the triangular wedge pin and the positive triangular wedge, and continue to lift the pull ring to drive the central column to move upward, and at the same time drive the reverse triangular wedge to move upward and separate from the positive triangular wedge, the outer wall of the support column begins to shrink and no longer squeezes the screen tube, then take out the support column, and finally fix the mold top plate on the flange at the upper end of the mold shell to obtain an annular coal unit, which is then left to rest for use;

[0018] Step 5, repeating steps 1 to 4 to make multiple groups of annular coal briquette units. After the annular coal briquette units are made, the mold bottom plate of the first group of annular coal briquette units is removed, the mold top plate of the last group of annular coal briquette units is removed, and the mold bottom plates and mold top plates of the remaining annular coal briquette units are removed, the annular coal briquette units are laid flat, and multiple groups of annular coal briquette units are connected in sequence through flanges to obtain a simulated drilling state experimental device. Inside the simulated drilling state experimental device, the top end of the next-level screen tube is inserted into the wide mouth of the bottom of the previous-level screen tube, forming a continuous through cylindrical space similar to a drill hole, simulating the drilling state in the coal seam;

[0019] Step six, remove the reserved hole baffle on the mold shell as needed, install an air supply device, a water supply device or a pressure device at the reserved hole according to the specific experimental needs of the simulated drilling, simulate the changes in gas, liquid and mine pressure of the coal body around the borehole, and conduct an experiment to simulate the drilling state.

[0020] The beneficial effects of using the present invention are:

[0021] The present invention designs the structure of the annular coal briquette manufacturing device, which can complete the formation of internal through holes while manufacturing coal briquette. At the same time, the annular coal briquette manufacturing device and the simulated drilling state experimental device are designed accordingly, so that the manufactured annular coal briquette units can be assembled and spliced ​​into simulated drilling state experimental devices of different lengths by combining and splitting the annular coal briquette units according to specific experimental requirements, thereby making it more convenient to carry out simulated drilling state experiments.

[0022] The support column provided in the present invention has a telescopic expansion function, which provides additional pressure resistance for the screen pipe during the production of annular coal shapes, and is easier to install and disassemble, thereby improving the speed and stability of producing coal shapes.

[0023] The annular coal shape making device designed in the present invention has a screen tube inside which has a certain supporting function, which can not only maintain the integrity of the internal space of the annular coal shape, but also has water permeability and air permeability, and can more similarly simulate the coal seam drilling morphology, thereby better completing the simulated drilling state experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a front cross-sectional view of the present invention.

[0025] Figure 2 It is a schematic diagram of the structure of the screen tube of the present invention.

[0026] Figure 3 It is a front cross-sectional view of the screen tube of the present invention.

[0027] Figure 4 It is a front cross-sectional view of the support column of the present invention.

[0028] Figure 5 It is a front cross-sectional view of the central column of the present invention when it is in a pressed-down state.

[0029] Figure 6 For the present invention Figure 4 A partial enlarged view of part a.

[0030] Figure 7 It is a top view of the support column of the present invention.

[0031] Figure 8 It is a front cross-sectional view of the pressing plate of the present invention.

[0032] Fig. 9 It is a top view of the pressing plate of the present invention.

[0033] Fig.10 It is a structural schematic diagram of the reserved hole baffle of the present invention.

[0034] Fig.11 This is a front sectional view of the reserved hole baffle of the present invention.

[0035] Fig.12 It is a schematic structural diagram of the annular coal briquette unit of the present invention.

[0036] Fig.13 It is a schematic structural diagram of the experimental device for simulating drilling state of the present invention.

[0037] The accompanying drawings include: 1. mold shell, 101. flange, 102. reserved hole, 2. mold bottom plate, 201. bottom plate leg, 202. support column slot, 203. screen tube clip, 3. screen tube, 301. top of screen tube, 302. screen tube wall, 303. bottom of screen tube, 304. screen eye, 4. support column, 401. central column, 4011. pull ring, 4012. pull rope, 4013. reverse triangular wedge, 4014. triangular wedge pin, 4015. spring, 402. outer wall of support column, 4021. regular triangular wedge, 5. pressure plate, 501. pressure plate ring, 502. pressure plate transfer rod, 503. reserved hole of pressure plate, 6. reserved hole baffle, 601. outer edge of baffle, 602. baffle protrusion, 603. baffle screw hole, 7. mold top plate. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Embodiment 1

[0040] Reference Figures 1 to 11 , a device for making annular coal shapes in a simulated drilling state includes a mold shell 1, a mold bottom plate 2, a screen tube 3, a support column 4 and a pressing plate 5, the mold bottom plate 2 is assembled at the lower end of the mold shell 1, the screen tube 3 and the support column 4 are assembled at the middle of the upper surface of the mold bottom plate 2, and the support column 4 is inserted into the inside of the screen tube 3, the pressing plate 5 is inserted into the mold shell 1, and the pressing plate 5 is sleeved on the outside of the screen tube 3.

[0041] The annular space formed by the mold shell 1, the mold bottom plate 2, the screen tube 3 and the pressing plate 5 is used to make annular coal briquettes.

[0042] The support column 4 is used to support the screen tube 3 , ensure the integrity of the hole in the middle of the coal shape, and seal the screen holes 304 on the screen tube 3 .

[0043] Specifically, if Figure 1 As shown, flanges 101 are integrally formed at both upper and lower ends of the mold shell 1 , and a reserved hole 102 is opened on the side surface of the mold shell 1 , and a reserved hole baffle 6 is installed on the reserved hole 102 by screws.

[0044] The mold shell 1 and the mold bottom plate 2 and the mold top plate 7 are mounted together by means of a flange 101 and bolts and nuts.

[0045] During the process of making annular coal shapes, the reserved hole 102 is blocked by the reserved hole baffle 6. When conducting a simulated drilling state experiment, the reserved hole baffle 6 can be removed, and an air supply device, a water supply device or a pressure device can be installed at the reserved hole 102 to simulate the changes in gas, liquid and mine pressure of the coal body around the drilling hole.

[0046] The reserved hole baffle 6 consists of a baffle outer edge 601 and a baffle protrusion 602 . The baffle outer edge 601 is integrally formed on the outer peripheral surface of the baffle protrusion 602 . A baffle screw hole 603 is opened on the baffle outer edge 601 for installing the reserved hole baffle 6 on the mold shell 1 .

[0047] The thickness of the portion of the baffle protrusion 602 protruding relative to the baffle outer edge 601 is the same as the thickness of the mold shell 1 , and the diameter of the baffle protrusion 602 is the same as the diameter of the reserved hole 102 .

[0048] Specifically, if Figure 1 As shown, a support column mounting body is integrally formed in the middle of the mold base plate 2, a base plate support leg 201 is fixedly mounted on the lower surface of the mold base plate 2, and the lower surface of the base plate support leg 201 is coplanar with the lower surface of the support column mounting body, a support column clamping groove 202 is provided on the upper surface of the support column mounting body, and a screen tube clamp 203 is integrally formed on the upper surface of the support column mounting body, and the screen tube clamp 203 is an annular protrusion.

[0049] The mold bottom plate 2 mainly supports the entire device, and at the same time realizes the positioning and installation of the support column 4 and the screen tube 3 through the support column clamping groove 202 and the screen tube clamp 203.

[0050] Specifically, if Figure 2 and Figure 3 As shown, the sieve tube 3 includes a sieve tube top 301, a sieve tube wall 302 and a sieve tube bottom 303. The sieve tube top 301 and the sieve tube bottom 303 are respectively arranged at the upper and lower ends of the sieve tube wall 302. A wide opening is provided on the lower surface of the sieve tube bottom 303. The outer diameter of the sieve tube top 301 is equal to the inner diameter of the wide opening and the outer diameter of the sieve tube clip 203. A sieve hole 304 is provided on the outer surface of the sieve tube wall 302.

[0051] Specifically, the outer surface of the sieve tube wall 302 is a rough surface, and the inner surface of the sieve tube wall 302 is a smooth surface.

[0052] The design of the roughness of the inner and outer surfaces of the screen tube wall 302 can increase the friction with the outer coal sample and reduce the friction with the inner support column 4, thereby improving the molding effect of the annular coal shape and facilitating the movement of the support column 4.

[0053] Specifically, if Figures 4 to 7As shown, the support column 4 includes a central column 401 and a support column outer wall 402 , the central column 401 is inserted into the support column outer wall 402 , and the support column outer wall 402 is inserted into the screen tube 3 , and the central column 401 is inserted into the support column slot 202 .

[0054] The central column 401 can move up and down in the supporting column slot 202 .

[0055] The outer circumference of the central column 401 is evenly fixed with an inverted triangular wedge 4013, and the inner surface of the outer wall 402 of the support column is fixed with a regular triangular wedge 4021 corresponding to the inverted triangular wedge 4013. The outer circumference of the central column 401 is provided with a pin groove, the inner end of the pin groove is fixedly installed with a spring 4015, the outer end of the spring 4015 is fixedly installed with a triangular wedge pin 4014 inserted in the pin groove, and the triangular wedge pin 4014 is arranged between the upper and lower ends of the inverted triangular wedge 4013. The upper surface of the central column 401 is provided with a connecting groove located inside the central column 401 and connected to the pin groove, and the upper end of the connecting groove is plugged with a pull ring 4011, and a pull rope 4012 is fixedly installed between the pull ring 4011 and the triangular wedge pin 4014.

[0056] The structural design of the reverse triangular wedge 4013 and the regular triangular wedge 4021 enables the outer wall 402 of the support column to move outward when the central column 401 moves downward, thereby supporting the screen tube 3.

[0057] The design of the triangular wedge pin 4014 is that as the central column 401 moves downward, under the action of the equilateral triangular wedge 4021, the triangular wedge pin 4014 will move inwardly to compress the spring 4015, and finally move out and get stuck under the equilateral triangular wedge 4021 under the action of the spring force, thereby locking the central column 401. During the compression molding process of the annular coal shape, the pressure of the coal shape on the outer wall 402 of the support column can be prevented from causing the central column 401 to move upward, thereby preventing the deformation of the through hole in the middle of the annular coal shape, thereby ensuring that the outer wall 402 of the support column always supports the screen tube 3.

[0058] Specifically, if Figure 7 As shown, the outer wall 402 of the support column is composed of two semi-cylindrical shells, a slot is opened on the end surface of one semi-cylindrical shell, and a plug rod matching the slot is fixedly installed on the end surface of the other semi-cylindrical shell.

[0059] The outer wall 402 of the support column may also be designed to be composed of a plurality of arc-shaped plates to achieve better support for the screen tube 3 .

[0060] Specifically, if Figure 8 and Fig. 9As shown, the pressure plate 5 includes a pressure plate ring 501 and a pressure plate transfer rod 502. The outer diameter of the pressure plate ring 501 is equal to the inner diameter of the mold shell 1. The pressure plate transfer rod 502 is welded to the upper surface of the pressure plate ring 501. A pressure plate reserved hole 503 is opened in the middle of the pressure plate ring 501.

[0061] Embodiment 2

[0062] The method for making annular coal briquette in a simulated drilling state, using the device for making annular coal briquette in a simulated drilling state as in the first embodiment, specifically comprises the following steps:

[0063] Step 1: Place the mold base plate 2 on the ground, fix the mold shell 1 on the mold base plate 2 through the flange 101, and use the reserved hole baffle 6 to block the reserved hole 102 on the mold shell 1;

[0064] Step 2: put the screen tube 3 into the mold shell 1, insert the screen tube bottom 303 into the screen tube clamp 203, insert the support column 4 from the screen tube 3, insert the lower end of the central column 401 into the support column clamping slot 202, and under the action of gravity, the inverse triangular wedge 4013 on the central column 401 is located on the equilateral triangular wedge 4021 on the inner side of the support column outer wall 402, and then press the central column 401 downward to make the inverse triangular wedge 4013 and the equilateral triangular wedge 4021 squeeze each other until the triangular wedge pin 4014 is stuck under the equilateral triangular wedge 4021, so that the support column outer wall 402 is opened outward and close to the inner wall of the screen tube 3;

[0065] Step 3: Pour coal samples into the mold shell 1 in batches, pour 5-10 cm deep coal samples each time, flatten the coal samples, and place the pressing plate 5 on the top of the coal samples by operating the pressing plate transfer rod 502 to compact the coal samples. The coal samples are confined in the space formed by the mold shell 1, the mold bottom plate 2, and the pressing plate 5. The middle position of the coal samples is occupied by the screen tube 3 and the support column 4. The coal samples can be pressed into a ring shape to obtain a ring-shaped coal mold.

[0066] Step 4, when the space of the mold shell 1 is completely filled and compacted by the coal sample, take out the pressing plate 5, lift the pull ring 4011 upward, the pull ring 4011 drives the triangular wedge pin 4014 to move inward through the pull rope 4012, releases the locking relationship between the triangular wedge pin 4014 and the positive triangular wedge 4021, continues to lift the pull ring, drives the central column 401 to move upward, and at the same time drives the reverse triangular wedge 4013 to move upward and separate from the positive triangular wedge 4021, the outer wall 402 of the support column begins to shrink and no longer squeezes the screen tube 3, then takes out the support column 4, and finally fixes the mold top plate 7 on the flange 101 at the upper end of the mold shell 1, as shown in FIG. Fig.12 As shown, a ring-shaped coal briquette unit is obtained and is kept still for use;

[0067] Step 5, repeating steps 1 to 4 to make multiple groups of annular coal briquette units. After the annular coal briquette units are made, the mold bottom plate 2 of the first group of annular coal briquette units is removed, the mold top plate 7 of the last group of annular coal briquette units is removed, and the mold bottom plates 2 and mold top plates 7 of the remaining annular coal briquette units are removed, the annular coal briquette units are laid flat, and multiple groups of annular coal briquette units are sequentially connected through flanges 101, as shown in FIG. Fig.13 As shown, a simulated drilling state experimental device is obtained. Inside the simulated drilling state experimental device, the top 301 of the next-level screen pipe is inserted into the wide mouth of the bottom 303 of the previous-level screen pipe, forming a continuous cylindrical space similar to a borehole, simulating the drilling state in the coal seam;

[0068] Step six, remove the reserved hole baffle 6 on the mold shell 1 as needed, install an air supply device, a water supply device or a pressure device at the reserved hole 102 according to the specific experimental needs of the simulated drilling, simulate the changes in gas, liquid and mine pressure of the coal body around the drilling hole, and conduct an experiment to simulate the drilling state.

[0069] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present invention. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A device for making annular coal briquette simulating drilling state, characterized in that: It includes a mold shell, a mold base, a screen tube, a support column and a pressure plate. The mold base is assembled at the lower end of the mold shell, the screen tube and the support column are assembled at the middle of the upper surface of the mold base, and the support column is inserted into the inside of the screen tube. The pressure plate is inserted into the mold shell, and the pressure plate is sleeved on the outside of the screen tube. The outer surface of the screen tube wall is provided with screen holes. The support column is used to support the screen tube and seal the screen holes on the screen tube.

2. The device for making annular coal briquette simulating drilling state according to claim 1, characterized in that: Flanges are integrally formed at both the upper and lower ends of the mold shell, and a reserved hole is opened on the side surface of the mold shell, and a reserved hole baffle is installed on the reserved hole by screws.

3. The device for making annular coal briquette simulating drilling state according to claim 2, characterized in that: A support column mounting body is integrally formed in the middle of the mold bottom plate, a bottom plate support leg is fixedly mounted on the lower surface of the mold bottom plate, and the lower surface of the bottom plate support leg is coplanar with the lower surface of the support column mounting body, a support column clamping groove is opened on the upper surface of the support column mounting body, a screen tube clamp is integrally formed on the upper surface of the support column mounting body, and the screen tube clamp is an annular protrusion.

4. The device for making annular coal briquette simulating drilling state according to claim 3, characterized in that: The sieve tube comprises a sieve tube top, a sieve tube wall and a sieve tube bottom. The sieve tube top and the sieve tube bottom are respectively arranged at the upper and lower ends of the sieve tube wall. A wide opening is opened on the lower surface of the sieve tube bottom, and the outer diameter of the sieve tube top is equal to the inner diameter of the wide opening and the outer diameter of the sieve tube clip.

5. The device for making annular coal briquette simulating drilling state according to claim 4, characterized in that: The outer surface of the sieve tube wall is a rough surface, and the inner surface of the sieve tube wall is a smooth surface.

6. The device for making annular coal briquette simulating drilling state according to claim 5, characterized in that: The support column comprises a central column and an outer wall of the support column, the central column is inserted into the outer wall of the support column, and the outer wall of the support column is inserted into the screen tube, and the central column is inserted into the support column slot; The outer circumference of the central column is evenly fixed with inverted triangular wedges, the inner surface of the outer wall of the support column is fixed with a regular triangular wedge corresponding to the inverted triangular wedge, the outer circumference of the central column is provided with a pin groove, the inner end of the pin groove is fixed with a spring, the outer end of the spring is fixed with a triangular wedge pin inserted in the pin groove, and the triangular wedge pin is arranged between the upper and lower ends of the inverted triangular wedge, the upper surface of the central column is provided with a connecting groove located inside the central column and connected with the pin groove, the upper end of the connecting groove is plugged with a pull ring, and a pull rope is fixedly installed between the pull ring and the triangular wedge pin.

7. The device for making annular coal briquette simulating drilling state according to claim 6, characterized in that: The outer wall of the support column is composed of two semi-cylindrical shells, one of the semi-cylindrical shells has a slot on its end face, and the other semi-cylindrical shell has a plug rod that matches the slot fixedly mounted on its end face.

8. The device for making annular coal briquette simulating drilling state according to claim 7, characterized in that: The pressure plate includes a pressure plate ring and a pressure plate transfer rod. The outer diameter of the pressure plate ring is equal to the inner diameter of the mold shell. The pressure plate transfer rod is welded to the upper surface of the pressure plate ring. A pressure plate reserved hole is opened in the middle of the pressure plate ring.

9. A method for making annular coal briquette in a simulated drilling state, using the device for making annular coal briquette in a simulated drilling state as claimed in claim 8, specifically comprising the following steps: Step 1: Place the mold base plate on the ground, fix the mold shell on the mold base plate through a flange, and use a reserved hole baffle to block the reserved hole on the mold shell; Step 2: put the screen tube into the mold shell, insert the bottom of the screen tube into the screen tube clamp, insert the support column from the screen tube, insert the lower end of the central column into the support column clamping slot, and under the action of gravity, the inverted triangular wedge on the central column is located on the regular triangular wedge on the inner side of the outer wall of the support column, and then press the central column downward to squeeze the inverted triangular wedge and the regular triangular wedge against each other until the triangular wedge pin is stuck under the regular triangular wedge, so that the outer wall of the support column opens outward and is close to the inner wall of the screen tube; Step 3: Pour coal samples into the mold shell in batches, pour 5-10 cm deep coal samples each time, flatten the coal samples, place the pressing plate on the top of the coal samples by operating the pressing plate transfer rod, and compact the coal samples. The coal samples are confined in the space formed by the mold shell, the mold bottom plate, and the pressing plate. The middle position of the coal samples is occupied by the screen tube and the support column, and the coal samples can be pressed into a ring shape to obtain a ring-shaped coal mold; Step 4: When the space of the mold shell is completely filled and compacted by the coal sample, take out the pressing plate, lift the pull ring upward, and the pull ring drives the triangular wedge pin to move inward through the pull rope, releasing the locking relationship between the triangular wedge pin and the positive triangular wedge, and continue to lift the pull ring to drive the central column to move upward, and at the same time drive the reverse triangular wedge to move upward and separate from the positive triangular wedge, the outer wall of the support column begins to shrink and no longer squeezes the screen tube, then take out the support column, and finally fix the mold top plate on the flange at the upper end of the mold shell to obtain an annular coal unit, which is then left to rest for use; Step 5, repeating steps 1 to 4 to make multiple groups of annular coal briquette units. After the annular coal briquette units are made, the mold bottom plate of the first group of annular coal briquette units is removed, the mold top plate of the last group of annular coal briquette units is removed, and the mold bottom plates and mold top plates of the remaining annular coal briquette units are removed, the annular coal briquette units are laid flat, and multiple groups of annular coal briquette units are connected in sequence through flanges to obtain a simulated drilling state experimental device. Inside the simulated drilling state experimental device, the top end of the next-level screen tube is inserted into the wide mouth of the bottom of the previous-level screen tube, forming a continuous through cylindrical space similar to a drill hole, simulating the drilling state in the coal seam; Step six, remove the reserved hole baffle on the mold shell as needed, install an air supply device, a water supply device or a pressure device at the reserved hole according to the specific experimental needs of the simulated drilling, simulate the changes in gas, liquid and mine pressure of the coal body around the borehole, and conduct an experiment to simulate the drilling state.

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