Intelligent variable-aperture drill bit based on surrounding rock stress sensing and control method of intelligent variable-aperture drill bit

Abstract

The invention belongs to the technical field of chamber surrounding rock drilling pressure relief, and particularly relates to an intelligent variable-aperture drill bit based on surrounding rock stress sensing and a control method thereof. Comprising a base, the center of the top of the base is provided with a water spraying barrel extending upwards, and the top of the water spraying barrel is provided with a drill bit used for drilling; the stress monitoring module is arranged in the drill bit; the reaming cutter assemblies are distributed in the circumferential direction and movably connected to the periphery of the base. The servo executing mechanism is arranged on the broaching cutter assembly and the joint of the broaching cutter assembly and the base; the control unit senses front surrounding rock stress in real time through the stress monitoring module arranged in the drill bit, accurate matching of the pressure relief aperture and the stress gradient is achieved by adopting the control logic of reducing the aperture through low stress, enlarging the aperture through high stress and stopping through dangerous stress, excessive damage to the surrounding rock in a low-stress area and material waste are avoided, and the drilling efficiency is improved. And thorough pressure relief and construction safety of a high-stress area are ensured.

Description

Technical Field

[0001] This application belongs to the field of pressure relief technology for drilling in surrounding rock of a tunnel, specifically relating to an intelligent variable diameter drill bit based on surrounding rock stress perception and its control method. Background Technology

[0002] In deep mines, tunnels, and other underground engineering projects, due to the interaction of geological structure, mining effects, and the shape of the chamber itself, the surrounding rock often exhibits a non-uniform distribution pattern of alternating and interlocking high-stress and low-stress zones. In high-stress zones, the accumulated enormous energy is the main source of dynamic disasters such as rockbursts and rock bursts, requiring the application of large-diameter stress relief holes to fully release stress, expand the plastic zone, and relieve pressure to transfer energy. However, if the same large diameter hole is used in the adjacent low-stress zone, it can easily cause excessive damage to the surrounding rock and increase support costs. Traditional chamber surrounding rock stress relief drilling technology with fixed parameters cannot adapt to the rapid changes in stress state within a short distance, resulting in low efficiency and high cost of chamber surrounding rock stress relief engineering. Therefore, there is an urgent need for a drill bit that can intelligently sense the stress state of the surrounding rock and dynamically adjust the borehole diameter in real time. Summary of the Invention

[0003] This invention provides an intelligent variable borehole drill bit and its control method based on surrounding rock stress sensing. By monitoring stress, the stress concentration of the surrounding rock in the chamber is determined, and the borehole size is precisely adjusted according to the stress concentration.

[0004] This application is achieved through the following technical solution: A smart variable-diameter drill bit based on surrounding rock stress sensing includes: a base, on which a water spray tube extending upward is provided at the top center, and a drill bit for drilling is provided at the top of the water spray tube; A stress monitoring module, located inside the drill bit, is used to collect stress data of the surrounding rock ahead of the drill bit in real time. Multiple reaming tool assemblies are circumferentially distributed and movably connected to the outer periphery of the base; A servo actuator is provided on the reamer assembly and at the connection between the reamer assembly and the base, for driving the reamer assembly to open or close. The control unit is electrically connected to the stress monitoring module and the servo actuator via a wireless communication module. The control unit is configured to: receive stress data and determine the current stress concentration level of the surrounding rock; generate a borehole diameter adjustment command based on the stress concentration level; and send it to the servo actuator to adjust the overall unfolding angle of the borehole reamer assembly in real time.

[0005] As described above, an intelligent variable-diameter drill bit based on surrounding rock stress sensing includes a main body for mounting the stress monitoring module and a cutting edge for drilling operations. The stress monitoring module is a stress sensor tightly fitted inside the main body, used to deform synchronously with the main body and generate a change in resistance value.

[0006] As described above, an intelligent variable-diameter drill bit based on surrounding rock stress sensing includes a servo actuator comprising a servo motor located at the connection between the reamer assembly and the base, and a gear connected to the output end of the servo motor. An internal gear ring is provided inside the hinge joint between the reamer assembly and the base, and the gear meshes with the internal gear ring.

[0007] As described above, an intelligent variable borehole drill bit based on surrounding rock stress sensing includes a servo motor, a gear set for amplifying torque, a control circuit board, and a potentiometer. After receiving a borehole adjustment command, the control circuit board controls the motor to drive the gear set to rotate, thereby driving the internal gear ring and adjusting the opening angle of the reaming cutter assembly. The potentiometer is linked with the gear to provide real-time feedback on the current angle.

[0008] As described above, in an intelligent variable borehole drill bit based on surrounding rock stress sensing, the outer wall of the base is uniformly provided with multiple discharge channels for discharging coal and rock slag.

[0009] As described above, in an intelligent variable-diameter drill bit based on surrounding rock stress sensing, the water jet cylinder has multiple nozzles evenly arranged on its two outer walls along its height direction for spraying water jets outward to provide hydraulic power for slag removal and to cool the borehole reamer assembly.

[0010] A control method based on the intelligent variable borehole diameter drill bit as described above includes the following steps: S1: Activate the stress monitoring module, wirelessly receive the real-time raw stress data of the drilling area collected by it, and filter the raw data to obtain a stable effective stress value; S2: Compare the effective stress value with a preset safety threshold range to determine the stress concentration level of the surrounding rock in the current drilling area; S3: Generate a target borehole diameter command based on the stress concentration level of the surrounding rock and wirelessly send it to the servo actuator to drive the reaming cutter assembly to adjust the opening and closing angle; S4: Confirm the actual borehole diameter through the position feedback signal of the servo actuator. If the deviation between the actual borehole diameter and the target borehole diameter is within the allowable range, maintain the current borehole diameter and continue drilling and return to step S1; if the deviation exceeds the range, re-output the adjustment command until the deviation reaches the target.

[0011] As described above, when controlling the hole-reaming cutter assembly to perform hole-reaming operations, the water spray tube is simultaneously activated to spray water jets through the spray nozzle, using water power to flush away the coal and rock slag and guide it to the discharge trough of the base for discharge.

[0012] In the control method described above, in step S3, the target borehole diameter command based on the stress concentration level of the surrounding rock is configured as follows: when it is determined to be a low stress concentration zone, a borehole diameter reduction command is generated to reduce the disturbance of the borehole to the surrounding rock; when it is determined to be a high stress concentration zone, a borehole diameter enlargement command is generated to release the concentrated stress; when it is determined to be a dangerous stress zone, a shutdown command is directly output.

[0013] In the control method described above, in step S1, a moving average filtering algorithm is used to remove random noise from the original data in order to obtain the effective stress value.

[0014] Compared with the prior art, this application has the following advantages: 1. It abandons the traditional fixed-diameter pressure relief mode and uses the stress monitoring module built into the drill bit to sense the stress of the surrounding rock in real time. It adopts the control logic of reducing the diameter under low stress, increasing the diameter under high stress, and stopping the machine under dangerous stress. This achieves precise matching between the pressure relief diameter and the stress gradient, which avoids excessive damage to the surrounding rock and material waste in the low-stress zone, and ensures complete pressure relief and construction safety in the high-stress zone.

[0015] 2. The servo actuator integrates a potentiometer inside the servo motor, which can mechanically link with the transmission gears to sense and provide feedback on the actual opening angle of the reamer in real time. The control system dynamically corrects the deviation between the actual hole diameter and the target hole diameter by comparing them, forming a tight closed-loop control circuit, thereby ensuring extremely high accuracy of the drilling diameter.

[0016] 3. The water jet nozzles of the water spray tube simultaneously spray water jets during the hole reaming operation, using water power to quickly flush away the cut coal and rock debris, and smoothly guide it out through the drainage groove on the outer wall of the base, fundamentally reducing the risk of stuck drill and buried drill; at the same time, the continuous water flow has an excellent cooling effect on the high-speed rotating hole reamer assembly, greatly reducing tool wear. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the principle of this application; Figure 2 This is a three-dimensional perspective view of the application in its collapsed state; Figure 3 This is a front view of the base and water spray nozzle of this application; Figure 4This is a schematic diagram of the reamer assembly of this application; Figure 5 This is a three-dimensional perspective view of the servo motor and gears of this application; Figure 6 This is a schematic diagram of the internal structure of the servo motor in this application; Figure 7 This is a three-dimensional perspective view of the application in its open state (one). Figure 8 This is a three-dimensional perspective view of the second open state of this application; Figure 9 This is a flowchart of the control method of this application. Detailed Implementation

[0019] To make the technical problems, solutions, and beneficial effects solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] Please see Figures 1 to 9 A smart variable-diameter drill bit based on surrounding rock stress sensing includes: a base 1, with a water spray tube 2 extending upward at the top center of the base 1, and a drill bit 3 for drilling at the top of the water spray tube 2. The stress monitoring module 4 is located inside the drill bit 3 and is used to collect stress data of the surrounding rock ahead of the drill in real time. Multiple reaming tool assemblies 5 are circumferentially distributed and movably connected to the outer periphery of the base 1; A servo actuator 6 is provided on the reamer assembly 5 and at the connection between the reamer assembly 5 and the base 1, for driving the reamer assembly 5 to open or close. The control unit 7 is electrically connected to the stress monitoring module 4 and the servo actuator 6 via a wireless communication module 8. The control unit 7 is configured to: receive stress data and determine the stress concentration level of the current surrounding rock; generate a borehole diameter adjustment command based on the stress concentration level; and send it to the servo actuator 6 to adjust the overall unfolding angle of the borehole reamer assembly 5 in real time.

[0021] In this embodiment, the working principle is as follows: during the drilling process, the drill bit 3 first performs preliminary drilling, and the built-in stress monitoring module 4 collects the deformation and stress data of the surrounding rock in front in real time. The data is transmitted to the control unit 7 via the wireless communication module 8. The control unit 7 evaluates the current geological stress concentration level based on a preset algorithm or safety threshold, and generates a dynamic borehole diameter adjustment command accordingly. This command is then wirelessly sent to the servo actuator 6. The servo actuator 6 generates a corresponding driving torque, which drives the multiple reaming cutter assemblies 5 on the outer periphery of the base 1 to perform precise opening or closing movements, thereby changing the overall borehole pressure relief diameter in real time. During this process, spraying... Water cylinder 2 continuously sprays water jets outward to achieve cooling and slag removal fluid dynamic assistance; the beneficial effects of this scheme are very significant. It breaks through the engineering bottleneck that traditional equal-diameter drill bits cannot adapt to rapid stress changes, and achieves precise adaptive matching between the pressure relief hole diameter and the geological stress gradient. This not only prevents excessive damage to the surrounding rock and construction waste in low-stress areas, but also ensures that energy can be fully released in high-stress areas to suppress dynamic disasters such as rock bursts. At the same time, the setting of wireless communication module 8 avoids the fatal defects of easy tangling and breakage of cables in high-speed rotational operations in deep holes, and greatly improves the operating life and monitoring reliability of the equipment under harsh working conditions.

[0022] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the drill bit 3 includes a main body 31 for mounting the stress monitoring module 4 and a cutting edge 32 for drilling operations. The stress monitoring module 4 is a stress sensor that is closely fitted inside the main body 31 and is used to deform synchronously with the main body 31 and generate a change in resistance value.

[0023] In this embodiment, the drill bit body can be made of medium carbon alloy structural steel, which has high strength, good toughness, good strain transmission linearity, and is easy to grind and attach strain gauges to, ensuring reliable signals. The drill bit cutting edge is made of cemented carbide, which does not affect the acquisition of internal stress signals. During drilling and decompression operations, the complex surrounding rock reaction force experienced by the cutting edge 32 at the front end is transmitted to the main body 31 at the rear. Because the stress monitoring module 4, such as the resistance strain gauge, is tightly and seamlessly bonded to the internal stress-bearing matrix of the main body 31 using a special adhesive, the micro-elastic mechanical deformation generated by the main body 31 under stress can be synchronously transmitted to the stress sensor without delay. This causes the sensitive element inside the sensor to stretch or compress, accurately converting the mechanical parameters into a linear electrical signal of resistance change. The beneficial effects of this structural design are extremely significant. On the one hand, through the physical isolation design of separating the main body and the cutting edge, the fragile electronic sensing element is hidden behind the cutting edge, which is far away from the severe cutting, high temperature and direct impact of rock debris, providing a robust physical protection barrier for the sensor and greatly reducing the wear and damage rate of the equipment under harsh mining conditions. On the other hand, the tightly fitted internal layout completely eliminates the force transmission gap, ensuring high fidelity and high sensitivity of stress sensing.

[0024] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the servo actuator 6 includes a servo motor 61 located at the connection between the reaming tool assembly 5 and the base 1, and a gear 62 connected to the output end of the servo motor 61. An internal gear ring 51 is provided inside the hinge joint between the reaming tool assembly 5 and the base 1, and the gear 62 meshes with the internal gear ring 51.

[0025] In this embodiment, when the control system issues a bore diameter adjustment command, the servo motor 61 located at the connection between the reamer assembly 5 and the base 1 receives the control signal and drives the internal motor to operate. The motor power is transmitted to the gear 62 through the output end. Since the gear 62 directly meshes with the internal gear ring 51 hidden inside the hinge, the rotational torque of the gear 62 is smoothly and without slippage converted into a tangential force that drives the internal gear ring 51 to rotate, thereby directly driving the entire reamer assembly 5 to deflect relative to the base 1 around the hinge axis, achieving a high-precision opening or closing action. The excellent effect of this transmission structure is very prominent. First, by using the direct meshing of the output gear 62 and the internal gear ring 51, the originally complex transmission system is highly integrated inside the narrow hinge node, which not only greatly saves the valuable space inside the drill bit, but also provides space for external discharge. The slag flow channel has sufficient capacity; secondly, the gear meshing transmission has extremely high rigidity and transmission ratio stability, which can withstand the huge reverse torque impact generated during deep surrounding rock reaming without deformation or slippage. Combined with the closed-loop feedback mechanism of the servo motor 61, it can achieve stepless, continuous and extremely precise angle control within the common range of 0 degrees to 180 degrees, completely eliminating the tedious process of frequently going up and down the drill bit to change different fixed hole diameters, greatly improving the efficiency of downhole operations. The servo motor 61 can be configured with multiple micro reduction gear sets in series to amplify the output torque of the motor multiple times to meet the power requirements of cutting extremely hard rock formations. At the same time, the meshing cavity of the gear 62 and the internal gear ring 51 can be filled with high-temperature resistant grease and sealed with multiple O-rings to prevent high-pressure water jets and coal and rock dust from entering and causing jamming.

[0026] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the servo motor 61 includes a motor 611, a gear set 612 for amplifying torque, a control circuit board 613, and a potentiometer 614. After receiving the aperture adjustment command, the control circuit board 613 controls the motor 611 to drive the gear 62 to rotate via the gear set 612, thereby driving the internal gear ring 51 and adjusting the opening angle of the reaming tool assembly 5. The potentiometer 614 is linked with the gear 62 to provide real-time feedback on the current angle.

[0027] In this embodiment, the servo motor 61 integrates a complete micro servo control system with drive, transmission, and closed-loop feedback. Its working principle is as follows: when the internal control circuit board 613 receives a bore diameter adjustment command from the system, such as a PWM pulse width modulation signal with a specific duty cycle, its built-in microcontroller parses the command and outputs a corresponding drive current to the motor 611, causing the motor 611 to run at high speed. Since the torque directly output by the motor 611 is usually small, this high-speed power is sequentially transmitted to the gear set 612, which acts as a reducer. After mechanical speed reduction and torque amplification through multi-stage gear meshing, the end-output gear 62 is driven to rotate in a low-speed, high-torque state. The gear 62 then strongly meshes with the internal gear ring 51 to overcome the surrounding rock resistance, precisely driving the reaming tool assembly 5 to open or close its deflection action. At each moment of this dynamic adjustment, the potentiometer 614, which is rigidly linked to the gear 62 or the corresponding output shaft, will mechanically rotate, and its internal resistance value will change accordingly, converting the actual physical angle of the tool into a real-time feedback voltage signal. The control circuit board 613 quickly performs a dynamic differential comparison between the actual feedback value and the target angle value set by the command. When the error between the two approaches zero, the power supply of the motor 611 is immediately cut off, and the current posture is maintained by mechanical self-locking or electromagnetic damping force of the motor, thus forming a tight physical closed-loop control circuit. The beneficial effects of this ingenious design are very significant. It not only provides the drill bit with the huge mechanical thrust necessary for forced diameter change and hole enlargement in deep, extremely hard rock formations through the gear set 612, but also avoids the phenomenon of overshoot or undershoot in hole diameter adjustment caused by severe vibration of downhole cutting, mechanical clearance of gears, or uneven backlash of rocks through the hardware-level closed-loop feedback mechanism built by potentiometer 614. At the same time, the highly integrated electromechanical micro-package greatly saves the extremely limited space inside the drill bit for slag removal and water channel layout. The motor 611 can be replaced by a brushless DC motor (BLDC) with a longer service life, stronger resistance to heat decay and no brush wear, or a stepper motor with higher control precision to provide smoother and more reliable bottom power output.

[0028] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the outer wall of the base 1 is provided with a plurality of discharge troughs 11 for discharging coal and rock slag evenly along the circumference.

[0029] In this embodiment, the drainage grooves 11 evenly distributed around the outer wall of the base 1 are used to remove coal and rock slag generated during drilling and reaming. Their working principle is that when the gear structure designed inside the base 1 drives the entire drill bit to rotate during drilling and reaming, the large amount of high-temperature coal and rock slag generated by the cutting and crushing of the front-end tool is rapidly flushed and guided backward by the centrifugal force generated by the rotation of the drill bit itself and the hydrodynamic force provided by the water jets sprayed from the water nozzles evenly distributed on both sides of the water jet. At this time, the multiple drainage grooves 11 evenly distributed around the circumference of the base 1 act as efficient drainage channels, allowing the mud-water slurry mixed with cooling water to smoothly pass over the outer perimeter of the base and be discharged outside the hole. The beneficial effect of this slag discharge and guiding structure is very significant; it fundamentally breaks the bottleneck of rock cuttings accumulation in the narrow space at the bottom of the borehole. This effectively avoids repeated breakage of the drill bit cutting surface due to poor slag discharge, thereby significantly reducing ineffective mechanical energy consumption during drilling. More importantly, the smooth slag discharge channel, combined with the cooling effect of the water column, can greatly reduce equipment wear and reduce the engineering risks of stuck drill and buried drill, thus balancing the safety of downhole construction and the long service life of the equipment. The discharge groove 11 is not limited to a vertical straight structure parallel to the axis of the base 1. It can be optimized and designed into a spiral groove adapted to the rotation direction of the drill bit according to the principles of fluid mechanics. This allows the spiral pumping effect to actively and forcefully transport and push the coal and rock slag to the rear of the borehole when the base 1 rotates, significantly enhancing the slag discharge kinetic energy. At the same time, the cross-sectional shape of the discharge groove 11 can be implemented as a streamlined U-shaped groove or a dovetail groove that is wider inside and narrower outside to reduce dead angles where rock slag gets stuck.

[0030] Furthermore, as a preferred embodiment of this solution and not a limitation, the water spray cylinder 2 has a plurality of spray nozzles 21 evenly arranged on the outer walls of both sides along its height direction for spraying water jets outward to provide hydraulic power for slag discharge and to cool the hole enlarging knife assembly 5.

[0031] In this embodiment, multiple water nozzles 21 are evenly arranged on the outer walls of both sides of the water spray cylinder 2 along its height direction. Its working principle is that during the drilling and diameter-adjusting operations of the intelligent drill bit in the surrounding rock of the underground chamber, high-pressure cooling water or water-based flushing fluid pumped in by the external drilling rig through the hollow drill rod continuously enters the inner cavity of the base and is conducted to the water spray cylinder 2. Subsequently, the high-pressure fluid is forced to be ejected at high speed from the evenly distributed multiple water nozzles 21, forming a powerful outward radial water column. These water columns directly and precisely impact the reaming cutter assembly 5 and its working surface, which are cutting the rock mass at high speed and generating intense frictional high temperatures. The beneficial effects of this structural design are significant. Firstly, the continuous high-speed water... The water jet can instantly remove the enormous heat generated when the cutting tool is cutting hard rock, completely avoiding the softening of the cutting teeth, alloy cracking, or accelerated wear caused by local overheating. This significantly extends the service life of expensive reaming tool assemblies. Secondly, the powerful jet of water provides ample fluid power to the working face, quickly flushing and pushing the cut coal and rock debris to the slag discharge channel behind the base. This eliminates the phenomenon of repeated cutting and rock breaking caused by rock cuttings accumulating at the bottom of the hole, greatly improving the efficiency of mechanical rock breaking and effectively curbing serious accidents such as stuck drills and buried drills that are prone to occur in engineering. In addition, the sprayed water mist can also play an excellent role in lubrication, dust suppression, and explosion prevention in the underground space of the mine.

[0032] A control method based on the intelligent variable borehole diameter drill bit as described above includes the following steps: S1: Activate the stress monitoring module 4, wirelessly receive the real-time raw stress data of the drilling area collected by it, and filter the raw data to obtain a stable effective stress value; S2: Compare the effective stress value with a preset safety threshold range to determine the stress concentration level of the surrounding rock in the current drilling area; S3: Generate a target borehole diameter command based on the stress concentration level of the surrounding rock and wirelessly send it to the servo actuator 6 to drive the reaming cutter assembly 5 to adjust the opening and closing angle; S4: Confirm the actual borehole diameter through the position feedback signal of the servo actuator 6. If the deviation between the actual borehole diameter and the target borehole diameter is within the allowable range, maintain the current borehole diameter and continue drilling and return to step S1; if the deviation exceeds the range, re-output the adjustment command until the deviation reaches the target.

[0033] In this embodiment, a complete closed-loop intelligent control system of "perception-decision-execution-feedback" is constructed. First, in step S1, the system starts the stress monitoring module 4 and uses wireless communication technology to cross the high-speed rotating mechanical interface to read the original stress data generated when the surrounding rock ahead of the drilling is cut in real time. The embedded filtering algorithm effectively removes random noise caused by high-frequency mechanical vibration of the drilling rig and downhole electromagnetic interference, and extracts the stable effective stress value that can truly reflect the geomechanical state. Then, in step S2, the effective stress value is substituted into the pre-set multi-level safety threshold range for comparison and calculation to accurately determine the high and low stress concentration level of the surrounding rock in the current working area. Following this, in step S3, the control unit, relying on its built-in decision logic model, calculates and generates a target borehole diameter adjustment command in real time based on the identified geological stress level. This command is then wirelessly transmitted to the servo actuator 6, triggering and driving the reaming cutter assembly 5 to perform the corresponding opening or closing action. Finally, in step S4, the system does not blindly assume that the command has been perfectly executed. Instead, it strictly verifies the deviation between the actual reaming diameter and the target borehole diameter by reading the position feedback signal from the internal sensor of the servo actuator 6 in real time. Only when the deviation is within the allowable tolerance range will the current posture be maintained to continue drilling and a new cycle be started; otherwise, fine-tuning will be triggered. The compensation mechanism re-outputs correction instructions until the target is fully met. This control method transforms the traditional static operation mode in underground engineering pressure relief drilling, which relies on experience, into a dynamic, adaptive, and intelligent stage. It not only achieves a perfect balance between thorough pressure relief and disaster prevention in high-stress areas and avoiding excessive damage to surrounding rock in low-stress areas by precisely matching the borehole diameter and stress gradient, greatly saving engineering support costs, but also fundamentally overcomes the industry-wide pain point of physical cables easily tangling and breaking under high-speed rotation conditions in deep-hole drill bits. Simultaneously, the front-end data filtering and the end-point position closed-loop feedback mechanism work together to ensure the absolute purity of the source decision data. This completely eliminates execution errors caused by mechanical transmission gaps or uneven rock thrust, significantly improving the overall system stability and final hole-forming accuracy of the drill bit in complex and harsh geological environments. The filtering process described in step S1 can specifically employ moving average filtering and Kalman filtering noise reduction algorithms to achieve better filtering effects for rock breaking and vibration noise at different frequency bands. The wireless receiving and transmitting actions described in steps S1 and S3 can be implemented using low-frequency long-wave ground-penetrating communication with strong anti-interference capabilities and good penetration, or intrinsically safe LoRa, ZigBee, and other wireless local area network transmission technologies optimized for confined and narrow underground spaces.The preset safety threshold range mentioned in step S2 can be not only a fixed expert experience constant statically recorded in advance based on on-site coal and rock mechanics experiments, but also a floating threshold model dynamically updated based on real-time cutting resistance feedback and machine learning algorithms, thereby enabling the drill bit to have increasingly intelligent geological adaptability. Furthermore, the position feedback signal confirmation method in step S4, in addition to relying on the analog voltage of a conventional potentiometer, can be equivalently replaced by a high-precision digital absolute magnetic encoder, or directly employ sensorless vector control (FOC) technology to precisely estimate the absolute position and orientation of the output shaft by real-time detection of the back electromotive force and phase current during motor operation.

[0034] Furthermore, as a preferred embodiment of this solution and not a limitation, when controlling the hole-reaming knife assembly 5 to perform hole-reaming operations, the water spray tube 2 is simultaneously activated to spray water jets through the water spray nozzle 21, using water power to flush away the coal and rock slag and guide it to the discharge trough 11 of the base 1 for discharge.

[0035] In this embodiment, when the reaming cutter assembly 5 is controlled to perform reaming operations, the water jet 2 is simultaneously activated to spray water jets through the water jet nozzles 21. This utilizes hydrodynamics to flush away coal and rock debris and guide it to the discharge trough 11 of the base 1 for discharge. The working principle is that when the control system determines that a diameter change is needed and drives the reaming cutter assembly to cut the surrounding rock, the system synchronously activates the hydraulic water circuit through electromechanical hardware and software collaborative logic. This allows high-pressure coolant supplied by an external drilling rig or high-pressure pump station to enter the water jet 2 along the hollow drill rod and be ejected as a high-speed jet from the surrounding water jet nozzles 21. The powerful high-pressure water jet directly and precisely impacts the working surface of the reaming cutter assembly 5, which is violently breaking the rock, instantly mixing the high-temperature coal and rock debris with the water flow. The jet's reaction energy and the entire drill bit... Driven by the centrifugal force generated by rotation, the slurry mixture is forced backward and smoothly discharged upward through the pre-drainage channel 11 on the outer periphery of the base 1, a dedicated low-resistance drainage channel. This scheme firstly rigidly synchronizes the water jetting and hole reaming operations in terms of timing, ensuring that forced fluid cooling can be obtained in time during the critical stage when the cutting load of the tool is the greatest and the frictional heat generation is the most intense. This completely avoids the decrease in hardness and rapid wear of the cutting teeth caused by local overheating and annealing, and significantly extends the service life of the drill bit. Secondly, the active slag removal using hydrodynamics combined with the dedicated drainage channel 11 fundamentally removes the rock cuttings accumulated at the bottom of the hole and the reaming step, eliminating the ineffective energy loss of repeated cutting of the broken rock cuttings by the tool, and significantly improving the rock breaking efficiency.

[0036] Furthermore, as a preferred embodiment of this solution and not a limitation, in step S3, the target borehole diameter command based on the stress concentration level of the surrounding rock is configured as follows: when it is determined to be a low stress concentration zone, a borehole diameter reduction command is generated to reduce the disturbance of the borehole to the surrounding rock; when it is determined to be a high stress concentration zone, a borehole diameter enlargement command is generated to release the concentrated stress; when it is determined to be a dangerous stress zone, a shutdown command is directly output.

[0037] In this embodiment, the working principle is as follows: the control unit incorporates a multi-level stress threshold determination model that matches the mechanical properties of the surrounding rock. When the effective stress value fed back by the sensor is lower than the first safety threshold, the system determines it to be a low stress concentration area. At this time, the control unit outputs an electrical signal to the servo mechanism through an algorithm to reduce the borehole diameter or maintain a basic small borehole diameter, causing the reamer to retract to reduce the cutting cross-section. When the stress value is between the first and second safety thresholds, it is determined to be a high stress concentration area that requires pressure relief. The system then outputs a command to enlarge the borehole diameter, driving the reamer to open to the corresponding diameter that can provide sufficient deformation compensation space. When the stress value suddenly increases and exceeds the highest warning limit, it is determined to be a dangerous stress area that is highly likely to induce rockburst or rockburst. The system will bypass the conventional adjustment loop and immediately trigger the highest priority emergency stop signal to interrupt the current drilling. This intelligent decision-making logic scheme... The beneficial effects are remarkable. It fundamentally solves the engineering problems of insufficient stress relief and excessive damage under low stress in traditional fixed-diameter pressure relief technology. In low-stress areas, reducing the borehole diameter maximizes the preservation of the original self-bearing strength of the surrounding rock in the chamber, avoiding the waste of support materials and ineffective consumption of working time caused by blindly drilling with large diameters. In high-stress areas, dynamic borehole expansion can accurately cut off the stress propagation path, providing a crucial physical discharge space for artificially inducing the expansion of the plastic zone of the surrounding rock, fully releasing and transferring high-accumulated energy to the depths. This effectively curbs the occurrence and development of dynamic disasters. Especially in dangerous areas facing the threat of extreme ground pressure, the millisecond-level automatic shutdown mechanism provides an extremely reliable ultimate defense against instantaneous compression deformation and damage to the drill bit and ensures on-site construction safety. It achieves the optimal dynamic balance between safety and economic efficiency in the pressure relief of chamber engineering disaster prevention.

[0038] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, in step S1, a moving average filtering algorithm is used to remove random noise from the original data in order to obtain the effective stress value.

[0039] The working principle of this embodiment is as follows: During drilling operations, the stress monitoring module built into the drill bit collects real-time data on the stress and deformation of the surrounding rock and sends it to the control unit via a wireless communication module. The control unit compares the stress concentration level with a preset safety threshold and generates a corresponding diameter change command, which is then sent to the servo actuator. The motor in the servo actuator drives the output gear after being reduced in speed and increased in torque by a gear set, which in turn drives the internal gear ring at the hinge of the reamer assembly to rotate, precisely adjusting the opening or closing angle of the cutter. The potentiometer provides real-time feedback to form a closed-loop control. At the same time, the water jet sprays high-pressure water jets to cool the cutting area and uses water power to push the coal and rock slag backward, efficiently discharging it out of the hole through the discharge groove on the outer wall of the base.

[0040] The above are implementation methods provided in conjunction with specific content, and it is not intended that the specific implementation of this application is limited to these descriptions. Any methods or structures that are similar to those of this application, or any technical deductions or substitutions made based on the concept of this application, should be considered within the scope of protection of this application.

Claims

1. An intelligent variable-diameter drill bit based on surrounding rock stress sensing, characterized in that, include: The base (1) has a water spray tube (2) extending upward at the center of its top, and the top of the water spray tube (2) is provided with a drill bit (3) for drilling. The stress monitoring module (4) is located inside the drill bit (3) and is used to collect stress data of the surrounding rock in front of the drill in real time. Multiple reaming knife assemblies (5) are circumferentially distributed and movably connected to the outer periphery of the base (1); A servo actuator (6) is provided on the reaming knife assembly (5) and at the connection between the reaming knife assembly (5) and the base (1), for driving the reaming knife assembly (5) to open or close. The control unit (7) is electrically connected to the stress monitoring module (4) and the servo actuator (6) via a wireless communication module (8). The control unit (7) is configured to receive stress data and determine the stress concentration level of the current surrounding rock, generate a hole diameter adjustment command based on the stress concentration level, and send it to the servo actuator (6) to adjust the overall unfolding angle of the hole reamer assembly (5) in real time.

2. The intelligent variable-diameter drill bit based on surrounding rock stress sensing according to claim 1, characterized in that, The drill bit (3) includes a main body (31) for mounting the stress monitoring module (4) and a cutting edge (32) for drilling. The stress monitoring module (4) is a stress sensor that is closely fitted inside the main body (31) and is used to deform synchronously with the main body (31) and generate a change in resistance value.

3. The intelligent variable-diameter drill bit based on surrounding rock stress sensing according to claim 1, characterized in that, The servo actuator (6) includes a servo motor (61) located at the connection between the reaming tool assembly (5) and the base (1), and a gear (62) connected to the output end of the servo motor (61). An internal gear ring (51) is provided inside the hinge between the reaming tool assembly (5) and the base (1), and the gear (62) meshes with the internal gear ring (51).

4. The intelligent variable-diameter drill bit based on surrounding rock stress sensing according to claim 3, characterized in that, The servo motor (61) includes a motor (611), a gear set (612) for amplifying torque, a control circuit board (613), and a potentiometer (614). After receiving the aperture adjustment command, the control circuit board (613) controls the motor (611) to drive the gear (62) to rotate through the gear set (612) to drive the internal gear ring (51), thereby adjusting the opening angle of the reaming tool assembly (5). The potentiometer (614) is linked with the gear (62) to provide real-time feedback on the current angle.

5. The intelligent variable-diameter drill bit based on surrounding rock stress sensing according to claim 1, characterized in that, The outer wall of the base (1) is evenly provided with multiple discharge troughs (11) for discharging coal and rock slag.

6. The intelligent variable-diameter drill bit based on surrounding rock stress sensing according to claim 1, characterized in that, The water spray cylinder (2) has multiple spray nozzles (21) evenly arranged on the outer walls of both sides along its height direction for spraying water jets outward to provide hydraulic power for slag discharge and to cool the hole enlarging knife assembly (5).

7. A control method for an intelligent variable borehole drill bit according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Start the stress monitoring module (4), wirelessly receive the real-time raw stress data of the borehole area collected by it, and filter the raw data to obtain a stable effective stress value; S2: Compare the effective stress value with the preset safety threshold range to determine the stress concentration level of the surrounding rock in the current borehole area; S3: Generate a target hole diameter command based on the stress concentration level of the surrounding rock, and wirelessly send it to the servo actuator (6) to drive the hole reamer assembly (5) to adjust the opening and closing angle; S4: Confirm the actual hole diameter through the position feedback signal of the servo actuator (6). If the deviation between the actual hole diameter and the target hole diameter is within the allowable range, maintain the current hole diameter and continue drilling and return to step S1; if the deviation exceeds the range, re-output the adjustment command until the deviation reaches the target.

8. The control method according to claim 7, characterized in that, When the hole enlarging knife assembly (5) is controlled to perform hole enlarging operation, the water spray tube (2) is started simultaneously to spray water through the water spray nozzle (21), and the coal and rock slag is flushed away by water power and guided to the discharge trough (11) of the base (1) for discharge.

9. The control method according to claim 7, characterized in that, In step S3, the target borehole diameter generation command based on the stress concentration level of the surrounding rock is configured as follows: when it is determined to be a low stress concentration zone, a borehole diameter reduction command is generated to reduce the disturbance of the borehole to the surrounding rock; when it is determined to be a high stress concentration zone, a borehole diameter enlargement command is generated to release the concentrated stress. When a hazardous stress zone is identified, a shutdown command is output directly.

10. The control method according to claim 7, characterized in that, In step S1, a moving average filtering algorithm is used to remove random noise from the original data in order to obtain the effective stress value.

Images