Aerial drill head and aerial drill

Abstract

The application provides a kind of roof rig cutter head and roof rig, comprising: inner cutter holder, outer cutter holder, telescopic drive device and control module;Outer cutter holder is set in the outer periphery of inner cutter holder and constitutes sliding fit along radial;Telescopic drive device is used to drive outer cutter holder to slide along radial telescopic;Control module is used to receive pressure signal and displacement signal and automatically control telescopic action.Specific use, control module drives its extension when the pressure of telescopic drive device is less than set threshold and duration exceeds first preset time, so that outer cutter holder expands to large diameter state and starts reaming;When the pressure is greater than set threshold and duration exceeds second preset time, stop reaming and drive outer cutter holder to retract.The application can realize multi-stage reaming in single operation, and can automatically adjust cutter head diameter in real time according to surrounding rock strength to avoid jamming, effectively improve construction efficiency and operation safety.

Description

Technical Field

[0001] This application relates to the field of mining machinery technology, and more specifically, to a cutterhead for a riser drilling rig and a riser drilling rig. Background Technology

[0002] As mining projects gradually extend deeper underground, the demand for large-diameter deep shafts is increasing. Currently, when performing reaming operations, shaft drilling rigs typically employ a construction process of first drilling a pilot hole and then proceeding with reaming. During the reaming stage, it is often necessary to replace the reamer head with different diameter specifications step by step according to the designed hole diameter requirements, performing multiple reaming operations to gradually enlarge the hole to the required size.

[0003] However, existing well drilling rig cutterheads and their reaming processes have many shortcomings. First, the step-by-step replacement of the reaming cutterhead leads to complicated construction procedures, not only increasing auxiliary operation time but also significantly reducing overall reaming efficiency. Second, repeated disassembly and replacement of the cutterhead for reaming easily causes borehole wall coaxiality deviations, seriously affecting well completion accuracy. Finally, most existing cutterheads are fixed-diameter structures, and once formed, they cannot be flexibly adjusted according to changes in the strength and structure of the surrounding rock downhole. When encountering complex geological conditions such as bottom rock fracturing and stress release, the cutterhead is easily jammed by the borehole wall due to its limited diameter, leading to equipment damage or even engineering safety accidents, resulting in poor construction safety and reliability. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a cutterhead and a well drilling rig to overcome the problems in the prior art.

[0005] In a first aspect, embodiments of this application provide a cutterhead for a well drilling rig, including an inner cutter post, an outer cutter post, a telescopic drive device, and a control module; The outer tool holder is fitted outside the inner tool holder and forms a radial sliding fit with the inner tool holder; The telescopic drive device is connected between the inner tool post and the outer tool post, and is used to drive the outer tool post to slide and extend radially relative to the inner tool post; The control module is used to receive pressure and displacement signals from the well drilling rig and automatically control the telescopic drive device to achieve automatic telescopic expansion and contraction of the cutterhead.

[0006] In some technical solutions of this application, multiple outer tool holders are provided, and the multiple outer tool holders are arranged concentrically, and each outer tool holder is respectively engaged with the corresponding guide groove on the inner tool holder; the telescopic drive device is a hydraulic cylinder, the number of hydraulic cylinders corresponds to the number of outer tool holders, and each hydraulic cylinder is used to drive one outer tool holder to slide and telescopic along the guide groove.

[0007] In some technical solutions of this application, an external toothed seat is fixedly connected to the external tool holder, and a fixed toothed seat, an internal toothed seat, and a central toothed seat are fixedly connected to the internal tool holder, which together constitute a multi-stage reaming tooth system.

[0008] In some technical solutions of this application, the above-mentioned telescopic drive device is a hydraulic cylinder, and the control module is configured as follows: The hydraulic cylinder pressure is detected. When the hydraulic cylinder pressure is less than the set pressure threshold and the duration exceeds the first preset time, the hydraulic cylinder is driven to extend, and the cutter head is expanded to a large diameter state. When the hydraulic cylinder is detected to have extended to the designated position, rock cutting and hole enlargement are initiated; If the pressure of the hydraulic cylinder is greater than the set pressure threshold and the duration exceeds the second preset time, the rock cutting will stop and the hydraulic cylinder will be driven to retract, and the cutter head will shrink to a small diameter state.

[0009] In some technical solutions of this application, when the telescopic drive device retracts, each outer tool holder retracts inward, and the diameter of the tool disc decreases to fit the pilot hole; when the telescopic drive device extends, the outer tool holder slides outward and locks, realizing the completion of multi-diameter hole enlargement in a single operation.

[0010] In some technical solutions of this application, a pull rod is also included; the pull rod passes through the center of the inner tool holder and is rigidly connected to the inner tool holder, for transmitting torque and providing tension force.

[0011] In some technical solutions of this application, the inner tool post is provided with a mechanical locking mechanism, which is used to lock and fix the outer tool post to the inner tool post after the hydraulic cylinder drives the outer tool post to slide outward along the guide groove to a designated position. In some technical solutions of this application, the control module includes a pressure sensor, a displacement sensor, and a hydraulic valve group; the pressure sensor is used to detect the pressure of the telescopic drive device, the displacement sensor is used to detect the sliding displacement of the outer tool holder, and the hydraulic valve group is used to control the action of the telescopic drive device according to the control command.

[0012] In some technical solutions of this application, the aforementioned tie rod is driven by a hydraulic system and can achieve axial extension, retraction, and rotation relative to the inner tool post.

[0013] Secondly, embodiments of this application provide a riser drilling rig, including the aforementioned riser drilling rig cutterhead.

[0014] The technical solutions provided by the embodiments of this application may include the following beneficial effects: This application provides a cutterhead for a riser drilling rig, including an inner cutter post, an outer cutter post, a telescopic drive device, and a control module. The outer cutter post is fitted outside the inner cutter post and forms a radial sliding fit with the inner cutter post. The telescopic drive device is connected between the inner and outer cutter posts and is used to drive the outer cutter post to slide and extend radially relative to the inner cutter post. The control module is used to receive pressure and displacement signals from the riser drilling rig and automatically control the telescopic drive device to achieve automatic telescopic expansion and contraction of the cutterhead.

[0015] This application employs a structural design that combines an inner and outer cutter head set together and slides radially, along with a telescopic drive device, to effectively achieve free adjustment of the overall diameter of the cutterhead. Simultaneously, by receiving and responding to pressure and displacement signals through a control module, the telescopic drive device's extension and retraction can be automatically controlled according to the surrounding rock strength, achieving automatic extension and retraction of the cutterhead. This overall technical solution fundamentally changes the traditional operation mode of borehole drilling rigs, which requires step-by-step cutterhead replacements for reaming. It significantly simplifies the construction process, effectively improves reaming efficiency, and indirectly ensures reaming accuracy by eliminating the need for frequent cutterhead disassembly and replacement. More importantly, its automatic extension and retraction function allows the cutterhead to flexibly adapt to changes in the rock strata structure and surrounding rock strength within the borehole, greatly reducing the risk of the cutterhead becoming stuck due to borehole wall shrinkage or geological changes, thereby significantly improving the safety and reliability of the construction operation.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram showing the unfolded shape of a cutterhead for a riser drill provided in an embodiment of this application is shown; Figure 2 This paper shows an overall schematic diagram of a well drilling rig cutterhead provided in an embodiment of this application. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0020] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0022] As mining projects gradually extend deeper underground, the demand for large-diameter deep shafts is increasing. Currently, when performing reaming operations, shaft drilling rigs typically employ a construction process of first drilling a pilot hole and then proceeding with reaming. During the reaming stage, it is often necessary to replace the reamer head with different diameter specifications step by step according to the designed hole diameter requirements, performing multiple reaming operations to gradually enlarge the hole to the required size.

[0023] However, existing well drilling rig cutterheads and their reaming processes have many shortcomings. First, the step-by-step replacement of the reaming cutterhead leads to complicated construction procedures, not only increasing auxiliary operation time but also significantly reducing overall reaming efficiency. Second, repeated disassembly and replacement of the cutterhead for reaming easily causes borehole wall coaxiality deviations, seriously affecting well completion accuracy. Finally, most existing cutterheads are fixed-diameter structures, and once formed, they cannot be flexibly adjusted according to changes in the strength and structure of the surrounding rock downhole. When encountering complex geological conditions such as bottom rock fracturing and stress release, the cutterhead is easily jammed by the borehole wall due to its limited diameter, leading to equipment damage or even engineering safety accidents, resulting in poor construction safety and reliability.

[0024] Based on this, this application provides a cutterhead for a riser drilling rig and a riser drilling rig, which are described below through embodiments. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] Figure 1 and Figure 2 The diagram shows a cutterhead for a riser drill provided in an embodiment of this application, including an inner cutter post 2, an outer cutter post, a telescopic drive device, and a control module.

[0026] The inner tool holder 2 forms the supporting base of the cutterhead of the well drilling rig. The outer tool holder is sleeved around the inner tool holder 2 and forms a radial sliding fit with the inner tool holder 2. Specifically, the outer tool holder and the inner tool holder 2 are engaged through guide grooves and guide parts, allowing the outer tool holder to slide reciprocally relative to the inner tool holder 2 in the radial direction. A telescopic drive device is connected between the inner tool holder 2 and the outer tool holder, used to output thrust or pull force to drive the outer tool holder to slide and extend radially under the guidance of the guide groove, thereby realizing the physical change of the cutterhead diameter. The control module receives pressure and displacement signals generated during the operation of the well drilling rig. The pressure signal reflects the external load pressure currently borne by the telescopic drive device in real time, while the displacement signal accurately reflects the actual position of the outer tool holder during the sliding process. The control module makes logical judgments based on these signals. When it is determined that the current signal meets the preset working conditions, the control module sends a control command to the telescopic drive device to drive it to extend or retract, thereby driving the outer tool holder to slide to the target position. Ultimately, the cutterhead automatically adjusts its diameter by expanding or retracting according to changes in the surrounding rock strength and working conditions.

[0027] In an optional embodiment, multiple outer tool holders are disposed around the inner tool holder 2, and the outer tool holders are arranged concentrically along the circumference. Each outer tool holder is embedded in a corresponding guide groove opened on the inner tool holder 2, thereby enabling each outer tool holder to slide in a directional manner along its corresponding guide groove. For example, four outer tool holders are configured: a first outer tool holder, a second outer tool holder 4, a third outer tool holder 5, and a fourth outer tool holder 6.

[0028] The telescopic drive device specifically uses hydraulic cylinders. The number of hydraulic cylinders corresponds one-to-one with the number of multiple outer tool holders. That is, each outer tool holder is equipped with a corresponding hydraulic cylinder. The cylinder body of the hydraulic cylinder is fixed on the inner tool holder 2, and its telescopic end is connected to the corresponding outer tool holder. Through the independent drive of each hydraulic cylinder, each corresponding outer tool holder can be driven to perform synchronous radial sliding telescopic extension and retraction along the guide groove. This allows multiple outer tool holders to work together to retract or expand radially, thereby adjusting the overall diameter of the tool disc in stages according to the actual hole enlargement requirements.

[0029] When the telescopic drive device retracts, each outer tool post retracts radially inward along the guide groove towards the center of the inner tool post 2. At this time, the overall diameter of the cutter head decreases accordingly, allowing the cutter head to be smoothly inserted and adapted to the pilot hole. When the telescopic drive device extends, each outer tool post slides radially outward along the guide groove, and after sliding out to the predetermined reaming position, it is reliably locked by the internal fitting structure. At this time, the diameter of the cutter head expands to the large diameter state, enabling large-diameter reaming cutting to be completed simultaneously during drilling.

[0030] Through the aforementioned telescopic movement, the cutterhead can complete the entire process from pilot hole adaptation to multi-stage reaming in a single well operation, achieving the goal of completing multi-diameter reaming in a single operation. This eliminates the need for disassembling and replacing cutterheads of different specifications in multiple operations, effectively avoiding the defects of frequent disassembly and assembly and complex procedures in traditional multi-stage reaming methods.

[0031] The inner tool holder 2 is also equipped with a mechanical locking mechanism. This mechanism locks the outer tool holder onto the inner tool holder 2 after the hydraulic cylinder drives it to slide outward along the guide groove to a pre-set position. The intervention of the mechanical locking mechanism effectively prevents the outer tool holder from radially retracting or slipping due to the enormous cutting reaction force during subsequent reaming operations. This ensures that the outer tool holder maintains reliable physical positioning after being deployed, thereby guaranteeing the stability of the large-diameter working state of the cutter head after deployment. This allows for smooth reaming operations, avoiding impacts on well completion accuracy and construction safety caused by force-induced shaking.

[0032] In an optional embodiment, a first external gear seat 7 is fixedly connected to the fourth outer tool holder 6, a second external gear seat 8 is fixedly connected to the third outer tool holder, and a fixed gear seat 9, an internal gear seat 10, and a central gear seat 11 are fixedly connected to the inner tool holder 2. The outer gear seat 7 undertakes the cutting operation in the outer region of the cutter head, while the fixed gear seat 9, internal gear seat 10, and central gear seat 11 on the inner tool holder 2 correspond to the cutting tasks in the middle section and center of the cutter head, respectively. The outer gear seat 7, fixed gear seat 9, internal gear seat 10, and central gear seat 11 work together to form a multi-stage reaming gear system containing cutting trajectories of different diameters. This multi-stage reaming gear system refers to the stepwise arrangement of cutting teeth of different diameters in the radial direction of the cutter head, enabling the cutter head to simultaneously cut annular cross-sections of different diameter ranges during rotation. Thus, multi-stage stepped reaming cutting can be completed in a single reaming operation, avoiding the cumbersome process of changing small cutter heads multiple times for stepwise reaming.

[0033] In an optional implementation, the telescopic drive device specifically employs a hydraulic cylinder, and the control module is configured with specific automatic control logic during actual operation. The control module receives and detects the working pressure of the hydraulic cylinder in real time. When the pressure of the hydraulic cylinder is less than the pressure threshold set by the system, and the low-pressure state lasts for more than a first preset time, it indicates that the surrounding rock strength of the currently contacted stratum is low and the resistance is small, meeting the conditions for hole reaming. The control module then sends a command to the hydraulic valve group to drive the hydraulic cylinder to extend, pushing the outer cutter head to slide outward along the guide groove, so that the cutter head is expanded to a large diameter state. During the extension of the hydraulic cylinder, the control module continuously receives displacement signals. When the displacement signal indicates that the hydraulic cylinder has extended to the preset designated position, the control module confirms that the outer cutter head has been fully extended and then sends a start command to the main unit of the well drilling rig to begin the rock cutting and hole reaming operation. During the rock cutting and borehole enlargement process, the control module continuously monitors the working pressure of the hydraulic cylinder. If the cylinder pressure is detected to be greater than the set pressure threshold and the high-pressure state lasts for more than the second preset time, it indicates that the strength of the surrounding rock has suddenly increased, the borehole enlargement resistance has increased sharply, or the borehole wall has contracted, and there is a risk of the cutter head getting stuck. At this time, the control module will immediately issue a command to stop rock cutting and drive the hydraulic cylinder to contract in the opposite direction, causing the outer cutter holder to retract inward along the guide groove, so that the cutter head is contracted to a small diameter state, thereby effectively avoiding equipment jamming accidents and ensuring the safety and stability of the overall construction process.

[0034] In an optional implementation, the control module's hardware core consists of a pressure sensor, a displacement sensor, and a hydraulic valve assembly. The pressure sensor detects the output pressure of the telescopic drive device in real time; the actual pressure value indirectly reflects the strength of the surrounding rock and the resistance during cutting. The displacement sensor detects the sliding displacement of the outer tool holder within the guide groove in real time, accurately feeding back the actual position of the outer tool holder during radial extension and retraction. The hydraulic valve assembly, driven by control commands from the control module, controls the on / off state and direction switching of the oil circuit of the telescopic drive device, thereby precisely controlling the extension or retraction of the telescopic drive device. Through the real-time sensing and acquisition of physical state quantities by the pressure and displacement sensors, and the precise switching of the hydraulic valve assembly according to control commands, the control module can form a closed-loop automatic control of the telescopic drive device, effectively ensuring the accuracy and reliability of the automatic extension and retraction of the cutterhead under complex surrounding rock conditions.

[0035] In an optional embodiment, the well drill cutterhead is also equipped with a tie rod 1, which passes through the central axis of the inner tool holder 2 and forms a rigid connection with the inner tool holder 2. In actual operation, the tie rod 1 mainly undertakes two core functions: firstly, it acts as the main transmission component to transmit the power of the well drill to the cutterhead, thereby realizing torque output; secondly, it provides the necessary tension force for the cutterhead during the cutting process to ensure the smooth progress of the reaming operation.

[0036] In addition, the tie rod 1 is driven by an independent hydraulic system. Under the driving action of the hydraulic system, the tie rod 1 can not only extend and retract axially relative to the inner cutter holder 2, but also rotate circumferentially around its own axis. This allows the cutter head to flexibly adjust its working posture according to the drilling depth and surrounding rock conditions during the drilling process, further improving the equipment's adaptability and operational flexibility in the face of complex downhole conditions.

[0037] In an optional implementation, during actual use, the cutterhead of the well drilling rig is first lowered into the pilot hole. At this time, the telescopic drive device is in a retracted state, and each outer cutter post retracts inward along the guide groove, keeping the overall diameter of the cutterhead small to smoothly adapt to the diameter of the pilot hole. When the cutterhead reaches the starting working face to be enlarged, as the cutterhead contacts the rock surface, the control module begins to receive pressure and displacement signals in real time for logical judgment. If the external load pressure on the telescopic drive device is less than the set pressure threshold, and the low-pressure state lasts for more than a first preset time (e.g., two seconds), the control module determines that the current surrounding rock strength is low and suitable for enlargement. It then issues a command to drive the telescopic drive device to extend, pushing the outer cutter posts to slide outward along the guide groove, thus expanding the cutterhead to a large-diameter working state. During the extension of the telescopic drive device, the displacement sensor continuously feeds back the actual position of the outer cutter posts. When the control module detects that the outer cutter posts have slid to the specified displacement, it confirms that the enlargement gear system has been fully extended and then starts the rock cutting and enlargement operation of the well drilling rig. During the subsequent continuous cutting process, the control module continues to monitor the pressure signal. If the load pressure of the telescopic drive device is greater than the set pressure threshold, and the high-pressure state lasts for more than the second preset time (e.g., 20 seconds), it indicates that the surrounding rock conditions have changed drastically or the hole wall has contracted, and there is a risk of the cutter head getting stuck. At this time, the control module immediately issues a command to stop cutting the rock and controls the telescopic drive device to contract in the opposite direction, driving the outer cutter holder to retract inward, and the cutter head returns to the small diameter state to avoid getting stuck. After the danger is eliminated, the hole can be enlarged again according to the above process.

[0038] Through this automatic judgment and execution process, the cutterhead of the well drilling rig in this application can adaptively complete the entire process of transitioning from pilot hole to large-diameter reaming according to the changes in the strength of the surrounding rock during actual construction. This not only effectively solves the inefficiency problem caused by the traditional method of changing the cutterhead multiple times, but also significantly improves the intelligence and safety reliability of construction operations in complex geological environments.

[0039] This application also provides a well drilling rig. The well drilling rig includes a frame, a drive mechanism, a drill rod, and a cutterhead as described in any of the above embodiments. The drive mechanism is fixedly mounted on the frame and is connected to the drill rod via a transmission connection. The drive mechanism outputs rotational power to drive the drill rod to rotate around its own axis. The cutterhead is mounted on the bottom end of the drill rod. During operation, the drill rod transmits the rotational torque generated by the drive mechanism to the cutterhead, which rotates synchronously with the drill rod to perform borehole enlargement cutting on the rock surface.

[0040] Specifically, the inner cutter head 2, outer cutter head, telescopic drive device, and control module in the cutterhead work together during drilling operations. The control module receives pressure and displacement signals from the riser drilling rig in real time during operation. Based on the signals, it automatically judges the current surrounding rock conditions and controls the extension or retraction of the telescopic drive device. The outer cutter head is driven to slide and extend radially under the guidance of the guide groove of the inner cutter head 2. This allows the cutterhead to automatically expand or contract its diameter according to the real-time changes in the strength of the surrounding rock downhole. As a result, the riser drilling rig can complete the entire process from adapting the pilot hole to multi-stage reaming in a single downhole operation. This effectively solves the problem of low construction efficiency caused by the need for repeated drilling and cutter head replacement for multiple reaming operations in traditional riser drilling rigs, and significantly improves the intelligence level and operational safety of deep mine riser drilling.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. All should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A cutterhead for a well drilling rig, characterized in that, Includes an inner tool post, an outer tool post, a telescopic drive device, and a control module; The outer tool holder is fitted outside the inner tool holder and forms a radial sliding fit with the inner tool holder; The telescopic drive device is connected between the inner tool post and the outer tool post, and is used to drive the outer tool post to slide and extend radially relative to the inner tool post; The control module is used to receive pressure and displacement signals from the well drilling rig and automatically control the telescopic drive device to achieve automatic telescopic expansion and contraction of the cutterhead.

2. The cutterhead of the well drilling rig according to claim 1, characterized in that, The outer tool holder is provided in multiple ways, and the multiple outer tool holders are arranged concentrically. Each outer tool holder is respectively engaged with the corresponding guide groove on the inner tool holder. The telescopic drive device is a hydraulic cylinder. The number of hydraulic cylinders corresponds to the number of outer tool holders. Each hydraulic cylinder is used to drive one outer tool holder to slide and telescopically along the guide groove.

3. The cutterhead of the well drilling rig according to claim 1, characterized in that, An external toothed seat is fixedly connected to the outer tool holder, and a fixed toothed seat, an internal toothed seat, and a central toothed seat are fixedly connected to the inner tool holder, together forming a multi-stage reaming tooth system.

4. The cutterhead of the well drilling rig according to claim 1, characterized in that, The telescopic drive device is a hydraulic cylinder, and the control module is configured as follows: The hydraulic cylinder pressure is detected. When the hydraulic cylinder pressure is less than the set pressure threshold and the duration exceeds the first preset time, the hydraulic cylinder is driven to extend, and the cutter head is expanded to a large diameter state. When the hydraulic cylinder is detected to have extended to the designated position, rock cutting and hole enlargement are initiated; If the pressure of the hydraulic cylinder is greater than the set pressure threshold and the duration exceeds the second preset time, the rock cutting will stop and the hydraulic cylinder will be driven to retract, and the cutter head will shrink to a small diameter state.

5. The cutterhead of the well drilling rig according to claim 1, characterized in that, When the telescopic drive device retracts, each outer tool holder retracts inward, and the diameter of the tool disc decreases to fit the pilot hole; when the telescopic drive device extends, the outer tool holder slides outward and locks, realizing the completion of multi-diameter hole enlargement in a single operation.

6. The cutterhead of the well drilling rig according to claim 1, characterized in that, Also includes: Pull rod; The pull rod passes through the center of the inner tool holder and is rigidly connected to the inner tool holder, used to transmit torque and provide tension force.

7. The cutterhead of the well drilling rig according to claim 2, characterized in that, The inner tool post is equipped with a mechanical locking mechanism, which is used to lock and fix the outer tool post to the inner tool post after the hydraulic cylinder drives the outer tool post to slide outward along the guide groove to a designated position.

8. The cutterhead of the well drilling rig according to claim 1, characterized in that, The control module includes a pressure sensor, a displacement sensor, and a hydraulic valve group; the pressure sensor is used to detect the pressure of the telescopic drive device, the displacement sensor is used to detect the sliding displacement of the outer tool holder, and the hydraulic valve group is used to control the action of the telescopic drive device according to the control command.

9. The cutterhead of the well drilling rig according to claim 6, characterized in that, The pull rod is driven by a hydraulic system and can extend, retract, and rotate axially relative to the inner tool post.

10. A well drilling rig, characterized in that, Includes the cutterhead of a well drilling rig as described in any one of claims 1 to 9.

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