A coal rock efficient drilling simulation system based on digital drilling and a method of using the same

Abstract

The present application relates to a kind of coal rock high-efficiency drilling simulation system based on digital drilling and its use method, belong to indoor drilling simulation technical field.System includes vertical drilling system, mobile control system, confining pressure loading system and control system, wherein, confining pressure loading system top is provided with mobile controller, mobile control system bottom is connected with vertical drilling system, vertical drilling system, mobile control system and confining pressure loading system are all connected with controller.The application can drill the test piece with moisture content by dry drilling method, and also can drill the test piece with moisture content by wet drilling method by injecting water into drill pipe, to study the influence of different drilling methods on drilling efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to a coal rock efficient drilling simulation system based on digital drilling and a use method thereof, and belongs to the technical field of indoor drilling simulation. BACKGROUND

[0002] In the coal mine underground drilling construction, whether the drilling machine can drill efficiently is a key factor affecting the efficiency of the coal mine underground drilling construction. For the floor drilling construction, the drilling machine drills from top to bottom, and the coal mine floor drilling efficiency is affected by various factors, including the lithology of the floor rock, the stress, and the mudified rock powder caused by the water in the hole and the incomplete cleaning of the rock powder in the hole. The floor drilling construction occupies an important position in the coal mine underground production, and only by determining the response characteristics between the water content of the rock, the lithology, the stress and the drilling parameters and how the response characteristics affect the drilling efficiency, the drilling efficiency can be improved by adjusting the appropriate drilling parameters of the drilling machine. Therefore, it is of great significance to develop a laboratory simulation system to study the influencing factors of the floor rock efficient drilling.

[0003] In order to simulate the drilling of the drilling machine indoors, the Chinese patent document CN112983252A discloses a top drive type micro drill experimental platform for indoor drilling simulation, which includes: the influence of the diameter and rotary speed of the diamond drill bit on the drilling efficiency in geological exploration can be studied through the power head assembly system, and the influence of the mudified rock powder on the drilling efficiency in the drilling process can be studied through the mud circulating system. The platform cannot apply confining pressure to the rock sample, so it cannot study the influence of different confining pressures on the drilling efficiency.

[0004] In order to study the influence of high temperature and high pressure and the drilling fluid system on the drilling speed in the drilling engineering, the Chinese patent document CN108952671A discloses an indoor drilling simulation device and evaluation method under multiple factor environment, which includes: the confining pressure and overburden pressure are applied to the rock sample through the pressure-bearing outer cylinder in the core clamping system, and the rock sample is heated by the electric heating device to simulate the influence of the downhole high temperature and high pressure environment on the drilling efficiency; the influence of different drilling fluid additives and drilling fluid systems on the drilling efficiency is studied through the high-pressure drilling fluid reciprocating circulation device and the drilling fluid flushing device. The device can record the drilling parameters of the drilling machine, but it cannot simultaneously investigate the influence of the water content of the rock, the lithology, the surrounding rock and the drilling parameters. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a coal rock efficient drilling simulation system based on digital drilling, which can study and analyze the key factors affecting efficient drilling under vertical drilling.

[0006] The present application also provides a use method of the coal rock efficient drilling simulation system based on digital drilling.

[0007] The technical scheme of the present application is as follows:

[0008] The coal rock efficient drilling simulation system based on digital drilling comprises a vertical drilling system, a movement control system, a confining pressure loading system and a control system, wherein the confining pressure loading system is provided with the movement controller at the top, the movement control system is connected with the vertical drilling system at the bottom, and the vertical drilling system, the movement control system and the confining pressure loading system are all connected with the controller.

[0009] The confining pressure loading system comprises a first counterforce frame, a second counterforce frame, a confining pressure loading oil cylinder, a fixed oil cylinder and a loading plate, the first counterforce frame is a rectangular frame, the movement control system is arranged at the top of the first counterforce frame, the second counterforce frame in the shape of C is vertically arranged at the bottom of the first counterforce frame, the fixed oil cylinder is arranged at one side of the second counterforce frame and one side of the first counterforce frame respectively, the confining pressure loading oil cylinder is arranged at the other side of the second counterforce frame and the other side of the first counterforce frame respectively, the fixed oil cylinder and the confining pressure loading oil cylinder are arranged on the same horizontal plane, and the loading plate is arranged on the output shaft of the fixed oil cylinder and the confining pressure loading oil cylinder.

[0010] According to the application, the movement control system comprises X-direction displacement sliding blocks, X-direction displacement rails, X-direction displacement screws, an X-direction motor, Y-direction displacement sliding blocks, Y-direction displacement rails, Y-direction displacement screws and a Y-direction motor, two X-direction displacement rails are arranged side by side at the top of the first counterforce frame, the X-direction displacement screws are arranged between the two X-direction displacement rails, the X-direction motor is connected with one end of the X-direction displacement screws, the X-direction displacement sliding blocks are slidably arranged on the X-direction displacement rails, the X-direction displacement screws are threadedly connected with the X-direction displacement sliding blocks, two Y-direction displacement rails are arranged side by side at the lower side of the X-direction displacement sliding blocks, the Y-direction displacement screws are arranged between the two Y-direction displacement rails, the Y-direction motor is connected with one end of the Y-direction displacement screws, the Y-direction displacement sliding blocks are slidably arranged on the Y-direction displacement rails, the Y-direction displacement screws are threadedly connected with the Y-direction displacement sliding blocks, and the vertical drilling system is arranged at the lower side of the Y-direction displacement sliding blocks.

[0011] According to the application, the vertical drilling system comprises a feeding oil cylinder, a drilling machine, a drill rod and a drill bit, the feeding oil cylinder is connected with the movement control system at the top, the drilling machine is arranged on the output shaft at the bottom of the feeding oil cylinder, the drill rod is connected with the drilling machine through a sleeve, and the drill bit is arranged at the end of the drill rod.

[0012] According to the application, the dynamic torque speed sensor is arranged between the output shaft at the bottom of the feeding oil cylinder and the drilling machine, the output torque and the rotation speed of the drill rod are monitored, the pull wire displacement sensor is arranged at one side of the feeding oil cylinder, the displacement of the drill rod is monitored, the oil pressure sensors are arranged on the confining pressure loading oil cylinder and the feeding oil cylinder, and the pressure loading value is determined conveniently.

[0013] According to the application, the drill rod is hollow, the sleeve is threadedly connected with the water injection pipeline, and the water injection pipeline injects water into the hollow part of the drill rod through the sleeve, so that the wet drilling of the test piece is completed.

[0014] According to the application, the second counterforce frame is provided with a groove on the bottom side, a bearing plate is arranged in the groove, the bearing plate and the second counterforce frame are provided with corresponding through holes, the groove has a depth greater than the thickness of the bearing plate, and the groove can collect water flowing out when the drill rod drills the test piece; a water pool is arranged in the first counterforce frame below the second counterforce frame, the water pool is externally connected to a sewage collecting barrel through a water pipe, the water pool collects water during drilling and discharges the water through the water pipe, and a filter screen is arranged on the water pool to filter the rock debris during drilling of the test piece.

[0015] The use method of the coal rock efficient drilling simulation system based on digital drilling is as follows:

[0016] (1) Making test pieces: large soft rock blocks with different mechanical properties and different water contents are collected from the engineering site, the large soft rock blocks are processed into cubic original rock test pieces with a size of 300mmx300mmx300mm, the soft rock obtained from the engineering site has a certain amount of water, the test pieces are weighed after drying, the water content of the original rock test pieces is measured according to the water content calculation formula, and several soft rock test pieces with different water contents and different mechanical properties are made;

[0017] Cubic casting test pieces with different mechanical properties are cast by using cement, river sand and water in different proportions, the prepared casting test pieces are placed in water, and several casting test pieces with different water contents are made according to different placement times and water contents;

[0018] One original rock test piece and one casting test piece with different water contents or different mechanical properties are taken for coring, each test piece is cored three times and subjected to uniaxial compression test, the average value of the three test results is obtained to obtain the rock mass mechanical property parameters of the test piece, including uniaxial compressive strength and elastic modulus;

[0019] (2) Placing test pieces: the complete original rock test pieces or casting test pieces with the same water content and different mechanical parameters are placed on the bearing plate, the extension of the oil cylinder is fixed to contact the test piece, and then the extension of the confining pressure loading oil cylinder is loaded; when the loading plate contacts the test piece, the confining pressure loading is stopped;

[0020] (3) drilling the test piece: adjusting the position of the drilling machine through the movement control system, then starting the drilling machine, setting the feeding speed and rotating speed, controlling the feeding cylinder to extend, and slowly moving the drill rod along the vertical direction to the test piece to complete the drilling operation on the test piece; collecting the drilling parameters in the drilling process through the oil pressure sensor, the wire displacement sensor and the dynamic torque speed sensor, including: displacement, feeding pressure, rotating pressure, torque, power, feeding speed and rotating speed; the displacement refers to the drilling depth of the drill rod, the feeding pressure refers to the hydraulic oil pressure of the feeding cylinder, the rotating pressure refers to the hydraulic oil pressure of the motor, both the rotating pressure and the feeding pressure are measured by the sensor, the power refers to the power supply, the feeding speed refers to the speed of the feeding mechanism in the drilling, and the rotating speed refers to the rotating speed of the main direction;

[0021] (4) drilling the original rock and the cast test piece with the same water content and different mechanical parameters to obtain the corresponding drilling parameters, and researching the response characteristic law between different lithology and drilling parameters in the drilling process.

[0022] According to the present application, the different confining pressures of the rock at different depths in the field are simulated, the confining pressure loading system is placed in the test piece with the same water content and mechanical properties, different confining pressures are applied to the test piece, and the response characteristic law between the confining pressure of the test piece and the drilling parameters is researched;

[0023] The original rock and the cast test piece with different water contents are placed in the confining pressure loading system under a certain confining pressure, and the response characteristic law between the water content of the rock and the drilling parameters in the drilling process is researched;

[0024] The test piece with the same water content or the same mechanical properties is placed, different feeding pressure, rotating pressure, torque, drilling speed and rotating speed and other drilling parameters of the drilling machine are set, and the influence of different drilling parameters on the drilling speed is researched.

[0025] For the test of the lithology, surrounding rock, water content and drilling parameter factors, multiple same original rocks and cast test pieces are drilled in one test to ensure the reliability of the test data.

[0026] According to the present application, when the wet drilling is performed, step (3) is that the position of the drilling machine is adjusted through the movement control system, then the drilling machine is started, the feeding speed and the rotating speed are set, the feeding cylinder is controlled to extend, the drill rod is slowly moved along the vertical direction to the test piece, water is injected into the drill rod through the water injection pipeline when the drill bit is 1-5 cm away from the test piece, then the drilling operation on the test piece is completed, the drilling parameters are obtained, and the remaining steps of the wet drilling are the same as those of the dry drilling.

[0027] The present application has the following advantages:

[0028] (1) The present application can drill into the test piece with moisture content by dry drilling, and can drill into the test piece with moisture content by wet drilling by injecting water into the drill rod, and the influence of different drilling modes on drilling efficiency is studied.

[0029] (2) The present application can control the drilling speed to collect drilling parameters such as drilling speed and torque, and on the other hand, the drilling speed can be controlled to collect drilling parameters such as drilling speed and torque, and the response characteristics of drilling parameters and rock properties in the drilling process are analyzed according to the collected drilling parameters.

[0030] (3) The present application can simulate vertical drilling of the floor, comprehensively study the response characteristics between drilling parameters and rock moisture content, rock properties (original rock and cast test piece), surrounding rock and other factors, and through analysis of these laws, how to select appropriate rotation speed and drilling speed and other drilling parameters to improve drilling efficiency under different drilling conditions is realized.

[0031] (4) The present application can apply load to test pieces of different rock properties according to the theory that the stress of rock is different at different floor depths and the rock strength of different rock layers is different, to simulate the stress field of real coal mine floor.

[0032] (5) The present application can realize multiple vertical drilling of the drilling machine in the XY plane through the movement control system, improving the test efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a front view of the structure of the present application.

[0034] Figure 2 is a rear view of the structure of the present application.

[0035] Figure 3 is a side view of the structure of the present application.

[0036] Figure 4 is a side view of the structure of the present application.

[0037] Figure 5 is a three-dimensional structure diagram of the movement control system of the present application.

[0038] Figure 6 is a front view of the X-direction displacement guide rail of the present application.

[0039] Figure 7 is a left view of the X-direction displacement guide rail of the present application.

[0040] Figure 8 is a top view of the X-direction displacement guide rail of the present application.

[0041] Figure 9 is a front view of the Y-direction displacement guide rail of the present application.

[0042] Figure 10 It is a left view of the Y-direction displacement guide rail of the present invention.

[0043] Figure 11 It is a top view of the Y-direction displacement guide rail of the present invention.

[0044] Among them: 1. First reaction frame, 2. Second reaction frame, 3. Loading plate, 4. Fixed cylinder, 5. Loading plate, 6. Drill rod, 7. Sleeve, 8. Drilling rig, 9. Y-axis displacement slider, 10. Y-axis displacement guide, 11. Feed cylinder, 12. X-axis displacement slider, 13. Y-axis motor, 14. X-axis displacement guide, 15. Wire displacement sensor, 16. Dynamic torque speed sensor, 17. Water injection pipeline, 18. Drill bit, 19. Oil pressure sensor, 20. Confining pressure loading cylinder, 21. Filter, 22. Water tank, 23. Water pipe, 24. Y-axis displacement screw, 25. X-axis displacement screw, 26. Top cover, 27. X-axis motor. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to embodiments and accompanying drawings, but is not limited thereto.

[0046] Example 1:

[0047] like Figures 1-11 As shown, this embodiment provides a coal and rock efficient drilling simulation system based on digital drilling, including a vertical drilling system, a mobile control system, a confining pressure loading system and a controller, wherein the mobile control system is provided on the top of the confining pressure loading system, and the bottom of the mobile control system is connected to the vertical drilling system, and the vertical drilling system, the mobile control system and the confining pressure loading system are all connected to the controller;

[0048] The confining pressure loading system includes a first reaction frame 1, a second reaction frame 2, a confining pressure loading cylinder 20, a fixed cylinder 4 and a loading plate 5. The first reaction frame 1 is a rectangular frame. A mobile control system is provided on the top of the first reaction frame 1. A C-shaped second reaction frame 2 is vertically fixed on the bottom of the first reaction frame 1. Fixed cylinders 4 are respectively provided on one side of the second reaction frame 2 and one side of the first reaction frame 1. Confining pressure loading cylinders 20 are respectively provided on the other side of the second reaction frame 2 and the other side of the first reaction frame 1. The fixed cylinder 4 and the confining pressure loading cylinder 20 are placed on the same horizontal plane, and loading plates 5 are provided on the output shafts of the fixed cylinder 4 and the confining pressure loading cylinder 20.

[0049] The mobile control system comprises an X-direction displacement slider 12, an X-direction displacement guide rail 14, an X-direction displacement screw 25, an X-direction motor 27, a Y-direction displacement slider 9, a Y-direction displacement guide rail 10, a Y-direction displacement screw 24 and a Y-direction motor 13, the top of the first counterforce frame 1 is provided with a top cover 26, the lower side of the top cover 26 is provided with two X-direction displacement guide rails 14 in parallel, the two X-direction displacement guide rails 14 are provided with the X-direction displacement screw 25, one end of the X-direction displacement screw 25 is connected with the X-direction motor 27, the X-direction displacement guide rail 14 is provided with the X-direction displacement slider 12 which is slidably arranged on the X-direction displacement guide rail 14, the X-direction displacement slider 12 is threadedly connected with the X-direction displacement screw 25, the lower side of the X-direction displacement slider is provided with two Y-direction displacement guide rails 10 in parallel, the two Y-direction displacement guide rails 10 are provided with the Y-direction displacement screw 24, one end of the Y-direction displacement screw 24 is connected with the Y-direction motor 13, the Y-direction displacement guide rail 10 is provided with the Y-direction displacement slider 9 which is slidably arranged on the Y-direction displacement guide rail 10, the Y-direction displacement slider 9 is threadedly connected with the Y-direction displacement screw 24, and the lower side of the Y-direction displacement slider 9 is provided with the vertical drilling system.

[0050] The vertical drilling system comprises a feeding oil cylinder 11, a drilling machine 8, a drill rod 6 and a drill bit 18, the feeding oil cylinder 11 is connected with the mobile control system at the top, the bottom output shaft of the feeding oil cylinder 11 is provided with the drilling machine 8, the output end of the drilling machine 8 is connected with the drill rod 6 through the sleeve 7, and the drill rod 6 is provided with the drill bit 18 at the end.

[0051] The dynamic torque speed sensor 16 is arranged between the bottom output shaft of the feeding oil cylinder 11 and the drilling machine 8, so as to monitor the output torque and the rotation speed of the drill rod, the feeding oil cylinder 11 is provided with the wire displacement sensor 15 on one side, so as to monitor the displacement of the drill rod, and the oil pressure sensor 19 is arranged on the feeding oil cylinder 11 and the confining pressure loading oil cylinder 20, so as to facilitate the determination of the pressure loading value.

[0052] The drill rod 6 is hollow, the sleeve 7 is threadedly connected with the water injection pipeline 17, and the water injection pipeline injects water into the hollow part of the drill rod through the sleeve, so as to complete the wet drilling of the test piece.

[0053] The second counterforce frame 2 is provided with a groove at the bottom, the groove is provided with the bearing plate 3, the bearing plate 3 and the second counterforce frame 2 are provided with corresponding through holes, the groove depth is greater than the bearing plate thickness, the water flowing out during the drilling of the test piece by the drill rod can be collected, the first counterforce frame 1 below the second counterforce frame 2 is provided with the water pool 22, the water pool 22 is externally connected with the sewage collection barrel through the water pipe 23, the water pool collects the water during the drilling process and discharges the water through the water pipe, and the water pool 22 is provided with the filter screen 21, so as to filter the rock debris during the drilling of the test piece.

[0054] The use method of the coal rock efficient drilling simulation system based on digital drilling is as follows:

[0055] (1) Making test pieces: Collecting large pieces of soft rock with different mechanical properties and different water contents from the engineering site, processing the large pieces of soft rock into cubic original rock test pieces with a size of 300mmx300mmx300mm, drying the test pieces, weighing them, measuring the water content of the original rock test pieces according to the water content calculation formula, and making several soft rock test pieces with different water contents and different mechanical properties;

[0056] Pouring test pieces with different mechanical properties of 300mmx300mmx300mm cubic test pieces with different proportions of cement, river sand and water, placing the prepared pouring test pieces in water, and making several pouring test pieces with different water contents according to different placement times and water contents;

[0057] Taking one original rock test piece and one pouring test piece with different water contents or different mechanical properties for coring, taking three times of each test piece for uniaxial compression test, and taking the average of the three test results to obtain the rock mechanical property parameters of the test piece, including uniaxial compressive strength and elastic modulus;

[0058] (2) Placing test pieces: Placing the complete original rock test pieces or pouring test pieces with the same water content and different mechanical parameters on the bearing plate, fixing the oil cylinder extension to contact the test piece, and then loading the oil cylinder extension with confining pressure, and stopping the confining pressure loading when the loading plate contacts the test piece;

[0059] (3) Drilling into the test piece: Adjusting the position of the drilling machine through the movement control system, then starting the drilling machine, setting the feed speed and rotation speed, controlling the extension of the feed cylinder, and slowly moving the drill rod along the vertical direction to the test piece to complete the drilling operation; collecting drilling parameters during drilling through oil pressure sensor, wire displacement sensor and dynamic torque speed sensor, including displacement, feed pressure, rotation pressure, torque, power, feed speed and rotation speed; displacement refers to the drilling depth of the drill rod, feed pressure refers to the hydraulic oil pressure of the feed cylinder, rotation pressure refers to the hydraulic oil pressure of the motor, rotation pressure and feed pressure are measured by sensors, power refers to the power supply, feed speed refers to the speed of the feed mechanism in drilling, and rotation speed refers to the rotational speed of the main direction;

[0060] (4) Drilling into the original rock and pouring test pieces with the same water content and different mechanical parameters to obtain corresponding drilling parameters, and studying the response characteristics between different lithology and drilling parameters during drilling.

[0061] Preferably, according to the different confining pressures of the rock at different depths on site, the confining pressures of the test pieces at different depths during drilling on site are simulated, the test pieces with the same water content and mechanical properties are placed in the confining pressure loading system, different confining pressures are applied to the test pieces, and the response characteristics between the confining pressure of the test piece and the drilling parameters are studied;

[0062] Keeping certain confining pressure, placing different water content of original rock and pouring test pieces in the confining pressure loading system, the response characteristic law between rock water content and drilling parameters in the drilling process is studied;

[0063] Placing test pieces with same water content or same mechanical properties, setting different feeding pressure, rotating pressure, torque, drilling speed and rotating speed of the drilling machine, the influence of different drilling parameters on drilling speed is studied.

[0064] For the test of investigating lithology, surrounding rock, water content and drilling parameter factors, multiple same original rock and pouring test pieces are drilled in one test to ensure the reliability of test data.

[0065] When wet drilling is performed, step (3) is to adjust the position of the drilling machine through the movement control system, then start the drilling machine, set the feeding speed and rotating speed, control the extension of the feeding cylinder, make the drill rod slowly move to the test piece along the vertical direction, when the drill bit is 1-5 cm away from the test piece, water is injected into the drill rod through the water injection pipeline, then the drilling operation on the test piece is completed, the drilling parameters are obtained, except step (3), the remaining steps of wet drilling are the same as those of dry drilling.

[0066] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method of using a coal rock efficient drilling simulation system based on digital drilling, characterized in that, The system comprises a vertical drilling system, a movement control system, a confining pressure loading system and a control system, wherein the confining pressure loading system is provided at the top of the movement control system, and the movement control system is connected with the vertical drilling system at the bottom, and the vertical drilling system, the movement control system and the confining pressure loading system are all connected with the controller; The confining pressure loading system comprises a first counterforce frame, a second counterforce frame, a confining pressure loading cylinder, a fixing cylinder and a loading plate, the first counterforce frame is a rectangular frame, the movement control system is arranged at the top of the first counterforce frame, the second counterforce frame is arranged at the bottom of the first counterforce frame in a C shape, the fixing cylinder is arranged at one side of the second counterforce frame and the first counterforce frame respectively, the confining pressure loading cylinder is arranged at the other side of the second counterforce frame and the first counterforce frame respectively, the fixing cylinder and the confining pressure loading cylinder are arranged on the same horizontal plane, and the loading plate is arranged on the output shaft of the fixing cylinder and the confining pressure loading cylinder; The second counterforce frame is provided with a groove at the bottom side, and a bearing plate is arranged in the groove, the bearing plate and the second counterforce frame are provided with corresponding through holes, the depth of the groove is greater than the thickness of the bearing plate, and a water pool is arranged in the first counterforce frame below the second counterforce frame, the water pool is connected with a sewage collecting barrel through a water pipe, and a filter screen is arranged on the water pool; The vertical drilling system comprises a feeding cylinder, a drilling machine, a drill rod and a drill bit, the movement control system is connected with the feeding cylinder at the top, the drilling machine is arranged on the output shaft of the feeding cylinder at the bottom, the drill rod is connected with the drilling machine through a sleeve at the output end, and the drill bit is arranged at the end of the drill rod; The dynamic torque speed sensor is arranged between the output shaft of the feeding cylinder at the bottom and the drilling machine, the pull wire displacement sensor is arranged at one side of the feeding cylinder, and the oil pressure sensor is arranged on the confining pressure loading cylinder and the feeding cylinder; The drill rod is hollow, and the sleeve is threadedly connected with a water injection pipeline; The use method of the coal rock efficient drilling simulation system based on digital drilling is as follows: (1) making test pieces: collecting large soft rock blocks with different mechanical properties and different water contents from the engineering site, processing the large soft rock blocks into cubic original rock test pieces with a size of 300mm*300mm*300mm, weighing the test pieces after drying, measuring the water content of the original rock test pieces according to the calculation formula of the water content, and making several soft rock test pieces with different water contents and different mechanical properties; Pouring test pieces with different mechanical properties of 300mm*300mm*300mm are made by using different proportions of cement, river sand and water, and the poured test pieces are placed in water, and several poured test pieces with different water contents are made according to different placement times and water contents; Take one piece of each of the original rock test pieces and the poured test pieces with different water contents or different mechanical properties for coring, and perform uniaxial compression test on each test piece for three times, and obtain the rock mechanical property parameters of the test piece by taking the average value of the three test results, including the uniaxial compressive strength and the elastic modulus; (2) placing test pieces: placing the original rock test pieces or the poured test pieces with the same water content and different mechanical parameters on the bearing plate, extending the fixing cylinder to contact the test piece, and then extending the confining pressure loading cylinder, and stopping the confining pressure loading when the loading plate contacts the test piece; (3) Drilling test piece: when dry drilling, the drilling position is adjusted by the movement control system, then the drilling machine is started, the feeding speed and rotation speed are set, the feeding cylinder is controlled to extend, the drill rod moves to the test piece along the vertical direction, and the drilling operation is completed; the drilling parameters are collected by the oil pressure sensor, the wire displacement sensor and the dynamic torque speed sensor; When wet drilling, the drilling position is adjusted by the movement control system, then the drilling machine is started, the feeding speed and rotation speed are set, the feeding cylinder is controlled to extend, the drill rod moves to the test piece along the vertical direction, when the drill bit is 1-5 cm away from the test piece, water is injected into the drill rod through the water injection pipeline, then the drilling operation is completed, and the drilling parameters are obtained; (4) The drilling parameters of the test pieces with the same water content and different mechanical parameters are obtained, and the response characteristics between different lithology and drilling parameters in the drilling process are studied.

2. The method of using the digital drilling based coal rock efficient drilling simulation system of claim 1, wherein, The movement control system comprises an X-direction displacement slider, an X-direction displacement guide rail, an X-direction displacement screw, an X-direction motor, a Y-direction displacement slider, a Y-direction displacement guide rail, a Y-direction displacement screw and a Y-direction motor, two X-direction displacement guide rails are arranged side by side at the top of the first counterforce frame, an X-direction displacement screw is arranged between the two X-direction displacement guide rails, one end of the X-direction displacement screw is connected with an X-direction motor, an X-direction displacement slider is slidably arranged on the X-direction displacement guide rail, the X-direction displacement slider is threadedly connected with the X-direction displacement screw, two Y-direction displacement guide rails are arranged side by side on the lower side of the X-direction displacement slider, a Y-direction displacement screw is arranged between the two Y-direction displacement guide rails, one end of the Y-direction displacement screw is connected with a Y-direction motor, a Y-direction displacement slider is slidably arranged on the Y-direction displacement guide rail, the Y-direction displacement slider is threadedly connected with the Y-direction displacement screw, and a vertical drilling system is arranged on the lower side of the Y-direction displacement slider.

3. The method of using the digital drilling based coal rock efficient drilling simulation system of claim 1, wherein, The test pieces with the same water content and mechanical properties are placed in the confining pressure loading system, different confining pressures are applied to the test pieces, and the response characteristics between the confining pressure of the test piece and the drilling parameters are studied; The test pieces with different water contents are placed in the confining pressure loading system under a certain confining pressure, and the response characteristics between the water content of the rock and the drilling parameters in the drilling process are studied; The test pieces with the same water content or the same mechanical properties are placed, different feeding pressures, rotation pressures, torques, drilling speeds and rotation speeds are set for the drilling machine, and the influence of different drilling parameters on the drilling speed is studied.

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