Self-adaptive deflection tubular object salvage device and salvage method for underground coal mine

Abstract

The invention discloses a device and a method for salvaging tubular objects capable of adaptively deflecting in an underground coal mine. The device comprises a drill rod joint connected with a drill rod, a double-spherical-hinge space multidirectional self-adaptive deflection mechanism, a guide rod and a slip assembly. The rear spherical hinge is used for compensating the deviation of the tubular object deviating from the center of the drill hole at a time; the guide rod is automatically aligned with the axis of the tubular object through self-adaptive fine adjustment of the front spherical hinge during pushing and placing. The guide rod is provided with double conical surfaces, a guide cone with a small front part and a large rear part is convenient to enter a pipe, a cone part with a small rear part and a large front part for clamping is matched with a slip wedge surface, and the self-locking function of contraction during pushing and expansion during pulling back is achieved. The two pairs of slips are symmetrically arranged, the two sections are wedged, and the locking force is increased along with the increase of the load. The whole mechanical structure is pure, hydraulic electric control is not needed, installation and maintenance are easy and convenient, and the device is suitable for underground narrow, humid and explosive environments. The corresponding salvage method comprises the following steps: observing a roadway and locking a rear spherical hinge to compensate offset; front spherical hinge damping is adjusted; self-adaptive alignment of pushing and placing is carried out; and the process is coherent and efficient.

Description

Technical Field

[0001] This invention relates to the field of underground equipment recovery technology in coal mines, specifically to a tubular object retrieval device that achieves adaptive deflection through a double ball joint connection system, which is particularly suitable for retrieving tubular objects such as extraction pipes and drill rods that are off-center from the borehole or in an inclined state. Background Technology

[0002] In underground coal mine gas drainage operations, pre-drainage of coal seam gas through boreholes is a core step in reducing the risk of coal and gas outbursts and achieving efficient development of gas resources. During construction, tubular materials such as drill rods and drainage pipes need to be laid and fixed smoothly along the centerline of the borehole; if they fall off or break, the tubular materials will remain trapped in the borehole at depths of hundreds or even thousands of meters.

[0003] Timely retrieval of these fallen tubular objects not only prevents equipment losses worth hundreds of thousands of yuan, but is also crucial to preventing borehole failure and ensuring the continuity of gas extraction. Therefore, tubular object retrieval devices are an indispensable tool in the downhole gas extraction technology chain.

[0004] However, existing retrieval tools exhibit significant shortcomings when dealing with tubular objects that are off-center and tilted. Taking the eccentric retrieval tool disclosed in patent application CN202320935713.1 as an example, while its design of offsetting the axis of the stabilizer and spear shaft improves its alignment capability for non-centered tubular objects to some extent, it still suffers from the following drawbacks: 1. The deflection angle is fixed, lacking self-adaptive capability, and cannot be adjusted according to the real-time changes in the deflection angle of the tubular object; 2. The single-slip structure results in uneven distribution of gripping force, which has limited locking effect on tubular objects with worn inner diameter and thinned wall thickness, and is prone to slippage; 3. The structure lacks a compensation mechanism for the offset distance of the tubular object from the borehole center. It is poorly adaptable to the special environment of underground coal mine drilling (narrow, humid, high vibration, and dusty), and is prone to failure due to vibration or torque. The success rate of docking is low under complex working conditions.

[0005] The direct technical reason for the aforementioned defects lies in the fact that existing technologies focus on a single-dimensional "external form-behavior" compensation approach regarding the "centralizer-spear shaft axis offset," that is, "approaching" the off-center tubular object by pre-setting a fixed eccentricity, while ignoring the complex working condition in three-dimensional space where the tubular object may simultaneously exhibit two degrees of freedom coupled: "axis tilt" and "center offset." Correspondingly, this invention establishes a novel technical route of "double ball joint two-stage spatial deflection + radial adaptive locking," achieving multi-directional adaptive deflection in space. Specifically, the front ball joint adjusts the alignment of the guide rod axis, and the rear ball joint compensates for the center offset distance; the combination of these two forms a dynamic alignment mechanism.

[0006] The aforementioned technical limitations lead to a chain reaction of problems when existing tools encounter complex and inclined conditions in coal mines: "difficulty in alignment - failure of gripping - secondary blockage." On the one hand, the fixed deflection angle cannot match the random tilt of the tubular object, and the guide rod is prone to rigid collision with the inner wall of the tubular object. On the other hand, the lack of center offset compensation capability makes it difficult for the tool axis to coincide with the axis of the tubular object, and the slip assembly cannot make uniform contact with the inner wall. In addition, the single slip design results in insufficient local friction when the inner wall of the tubular object wears, which can easily cause the tubular object to fall off during the retrieval process. This not only increases the risk of operation but may also cause secondary blockage of the borehole, further delaying the gas drainage period.

[0007] Therefore, given the complex working conditions of retrieving tubular objects in underground coal mines, there is an urgent need for a new type of retrieval device that can achieve multi-directional adaptive deflection in space and improve the stability of grasping, so as to solve the core defects of existing technologies such as fixed deflection angle, poor adaptive ability and uneven grasping force, and ensure the continuity and safety of borehole pre-drainage gas operation. Summary of the Invention

[0008] The purpose of this invention is to provide a self-adaptive deflection tubular object retrieval device for underground coal mines, solving the problems of existing retrieval tools being unable to compensate for the offset distance of the tubular object from the borehole center, and being difficult to align with the inclined pipe opening and reliably lock it after entry.

[0009] To achieve the above objectives, the present invention provides a tubular object retrieval device for retrieving tubular objects from a borehole, with the direction of penetration into the borehole being forward and the reverse direction being backward; it includes a drill pipe joint, a spatial multi-directional adaptive deflection mechanism, a guide rod, and a slip assembly for variable diameter locking; The drill pipe joint is used to connect to an external drill pipe and is driven by the drill pipe. The rear end of the spatial multi-directional adaptive deflection mechanism is rotatably connected to the front end of the drill pipe joint, which is used to align with the axis of the tubular object and compensate for the offset distance of the tubular object from the center of the borehole. The spatial multi-directional adaptive deflection mechanism is rotatably connected to the guide rod in the forward direction. The guide rod is provided with a clamping cone that is smaller at the back and larger at the front. The clamping slip assembly is sleeved on the clamping cone and is used to adaptively change the diameter and lock the tube wall when it is pulled back after entering the tube.

[0010] The spatial multi-directional adaptive deflection mechanism includes a double ball joint rod body, a rear ball seat at the rear end of the double ball joint rod body, a rear ball head rotatably assembled inside the rear ball seat, and the rear ball head and the rear ball seat forming a rear ball joint; the rear ball head is fixedly connected to the front end of the drill pipe joint, forming a rotational fit between the drill pipe joint and the rear ball seat; The front end of the double ball joint rod is provided with a front ball seat, and a front ball head is rotatably assembled inside the front ball seat. The front ball seat and the front ball head form a front ball joint; the front ball head is fixedly connected to the rear end of the guide rod, forming a rotational fit between the guide rod and the front ball seat. Both the front ball seat and the rear ball seat have external threads on their circumferential outer surfaces. The front ball seat is screwed with a front nut, and the rear ball seat is screwed with a rear nut. The front nut is used to balance stability of the push-out posture and adaptive deflection after entering the tubular object by adjusting the tightness. The rear nut is used to prevent angular changes between the drill pipe joint and the double ball joint during the push-out process by tightening it.

[0011] The slip assembly includes at least one pair of slips, the outer surface of which is an arc-shaped surface, and the radial inner surface of which is provided with a radially protruding slider or a radially recessed groove; the two slips in the pair are symmetrically distributed about the axis of the guide rod. The radial outer surface of the clamping cone of the guide rod is provided with a groove or slider that corresponds to and is adapted to the slider or groove. The slider is slidably engaged in the groove to ensure that the slip is in close contact with the radial outer surface of the clamping cone when it moves forward or backward relative to the guide rod, so that the relative forward and backward processes of the slip relative to the guide rod correspond to the opening and contraction processes of the slip, respectively.

[0012] The clamping cone and the corresponding slip assembly form a pair of wedge clamping devices. Two sets of wedge clamping devices are provided at intervals on the guide rod. The guide rod around the small diameter end of the clamping cone forms a step, and an expansion spring is provided between the step corresponding to each wedge clamping device and the slip assembly on the corresponding clamping cone.

[0013] The front end of the guide rod is provided with a guide cone that is smaller at the front and larger at the back. The guide cone is used to make it easy for the guide rod to enter the opening of the tube and to force the axes of the two to self-align during the process of the guide rod entering the tube.

[0014] The curved surface of the kava has anti-slip textures to increase the coefficient of friction with the inner wall of the tube.

[0015] The front end of the slider or groove set on the guide rod is provided with a limiting structure, which is used to limit the front limit position of the slider or groove set on the radial inner surface of the slip relative to the guide rod.

[0016] The present invention also provides a salvage method, which utilizes the aforementioned adaptive deflection tubular object salvage device for underground coal mines and performs the following steps: Before use, connect the upper end of the drill pipe connector to the drill pipe; the drill pipe connector and the rear ball joint are either integrally set or fixedly connected.

[0017] S1. Compensation for the offset distance of the tubular object from the borehole center: S1.1 Observation offset: Observe (visually or through camera) the position of the upper end of the tubular object that fell into the borehole relative to the center of the borehole, and obtain the offset distance information of the tubular object from the center of the borehole; S1.2 Adjustment and Compensation: Adjust the rear ball joint by using the displacement generated by the relative swing of the double ball joint rods to compensate for the offset distance of the tubular object from the borehole center. After adjustment, tighten the rear nut of the rear ball joint to lock the rear ball joint. S2. Adjust the front ball joint: Rotate the front nut of the front ball joint to adjust the preload on the front ball joint to adjust its rotational damping force so that the guide rod can maintain a stable posture when it is not subjected to external force and can adaptively deflect under the constraint of the inner wall of the tubular object. S3. Pushing and Adaptive Adjustment: The operator uses the drilling rig to push the adaptive deflection tubular retrieval device for underground coal mines into the borehole through the drill rod; because the compensation was made in advance in S1, the tip of the guide rod enters the upper end of the tubular object after being pushed. The constricting effect of the inner wall of the tubular structure forces the front ball joint to rotate adaptively, thereby achieving adaptive deflection and aligning the axis of the guide rod with the axis of the tubular structure. As the guide rod goes deeper, the slip assembly slides upward along the locking cone and contracts radially under the squeezing action of the inner wall of the tubular structure, compressing the expansion spring in the process.

[0018] S4. Pull-back retrieval: The operator uses the drilling rig to pull out the self-adaptive deflection tubular retrieval device used in underground coal mines. Under the combined action of the weight of the tubular object, the friction of the inner wall, and the release force of the expansion spring, the slip assembly slides downward relative to the guide rod along the clamping cone and expands radially, so that the arc-shaped surface of the slip assembly tightly fits the inner wall of the tubular object, achieving radial locking. This allows the retrieval of the tubular object to be pulled out of the borehole along with the self-adaptive deflection tubular retrieval device used in underground coal mines.

[0019] The present invention has the following advantages: The spatial multi-directional adaptive deflection mechanism forms a double-hinge structure through two rotating connections: the rear end is connected to the drill pipe joint, and the front end is connected to the guide rod. This allows for one-time compensation of the offset distance of the tubular object from the center of the borehole before it is pushed into the hole, and achieves spatial multi-directional adaptive alignment during the pushing process. This solves the problem that traditional fixed-angle mechanisms cannot cope with large-angle tilts.

[0020] The guide rod's tapered section, with its smaller rear end and larger front end, forms a wedge-shaped fit with the slip assembly. During push-out, the slip assembly slides backward along the tapered section and contracts radially, facilitating entry into the tubular object. During pull-back, the slip assembly slides forward along the tapered section and expands radially, generating self-amplifying force for locking. This achieves powerless adaptive variable diameter locking, resulting in a simple structure and high reliability.

[0021] The slip assembly is fitted onto the tapered part of the guide rod. It can contract during "forward" movement (when the tubular object moves forward, the slip assembly moves relatively backward relative to the guide rod, and the diameter of the clamping tapered part it contacts is smaller) and expand during "reverse" movement (when the diameter of the clamping tapered part it contacts is larger). The locking force increases with the increase of the pull-back load, ensuring uniform and firm gripping of the inner wall of the tubular object and reducing damage to the tubular wall.

[0022] The drill pipe joint, spatial multi-directional adaptive deflection mechanism, guide rod, and slip assembly are sequentially mechanically connected, enabling modular connection. This allows for direct replacement of existing drill pipe lower end tools without modifying the drilling rig system. Installation, disassembly, and maintenance are convenient, adapting to complex working conditions in coal mines.

[0023] The "tandem ball joint" structure consisting of a double ball joint rod, a front ball joint, and a rear ball joint has two advantages: ① The "rear ball head - rear ball seat" rotating joint of the rear ball joint allows for a one-time pre-adjustment of the angle to compensate for the offset distance of the tubular object from the borehole center; ②The “front ball head-front ball seat” rotating joint of the front ball joint continues to self-adaptively fine-tune during the pushing and releasing process, realizing multi-directional spatial alignment and significantly expanding the range of tilt angles that can be retrieved.

[0024] The integrated thread-locking design of the front / rear nut has two advantages: ① The front nut can be tightened to make fine and continuous adjustment of the rotational damping force between the front ball seat and the front ball head, so that the guide rod can be stable in posture when pushed out and can be flexibly deflected after entering the pipe opening, taking into account both "stability" and "flexibility". ② After tightening the rear nut, the relative angle of the "drill pipe joint - double ball joint rod body" is locked to prevent accidental rotation during the pushing and releasing process, which may cause compensation failure and improve the reliability of the operation.

[0025] The angle locking or resistance adjustment or unlocking can be achieved purely mechanically without external drive by simply tightening, adjusting or loosening the front nut or the rear nut. It requires no hydraulic or electronic control system, has a compact structure and is easy to maintain, and is especially suitable for the humid and explosive environment of underground coal mines.

[0026] The front ball joint and front nut correspond to the "alignment" function, while the rear ball joint and rear nut correspond to the "offset compensation" function. The "alignment" and "offset compensation" functions are separated, resulting in a simple structure and independent adjustment.

[0027] The radial inner surface of the collet is provided with a slider / groove, which forms a circumferential limiting sliding pair with the corresponding groove / slider on the outer surface of the cone that clamps the guide rod. This ensures that the collet remains in close contact with the outer surface of the cone throughout the entire "forward-backward" movement, without rotation or lateral displacement, thus improving motion stability.

[0028] The circumferentially limiting sliding pair also prevents the slip from leaving the clamping cone of the guide rod, so that the relative sliding of the slider in the groove is directly converted into the radial displacement of the slip along the clamping cone: As the slip retracts relative to the guide rod, it slides toward the small end of the locking cone, and the slip retracts to enter the opening of the tubular object.

[0029] As the slip moves forward relative to the guide rod, the slip slides from the tapered end (smaller at the back, larger at the front) to the larger end, thus opening and locking. At this point, the tubular object can be pulled out of the borehole. The opening and closing actions of the slip only need to be strictly matched with the pushing and pulling processes, without the need for additional drive. It has a simple structure, responds quickly, and achieves wedge tightening when the drilling rig pulls back and loosening when the pushing device is released. The action is reliable and simplifies the operation process.

[0030] The circumferentially distributed (symmetrical) structure of the slider-groove ensures that the arc-shaped surface of each slip fits evenly against the inner wall of the tube, resulting in a balanced distribution of locking force, reducing local indentations and wear, and improving gripping reliability and tube wall life.

[0031] Two sets of wedge clamping devices are arranged at intervals, forming a "double wedge clamping" structure on the guide rod. This creates two independent radial locking zones between the slip assembly and the inner wall of the tubular object, resulting in a more uniform axial distribution of the locking force and significantly reducing the risk of single-point slippage.

[0032] The expansion spring is placed between the step and the slip assembly, always providing the slip assembly with a force that can overcome resistance and move forward relative to the clamping cone. Even when fishing in an upward-sloping borehole, it can push the slip assembly forward relative to the clamping cone and open radially, achieving rapid response wedge locking and improving response speed and locking reliability.

[0033] Both sets of wedge clamping devices rely on the wedge surface geometry of the clamping cone and the expansion spring to form a double self-amplifying force effect: the greater the pull-back load, the greater the radial locking force. No external power is required, and the structure is simple and highly adaptable.

[0034] The guide cone adopts a streamlined shape with a smaller front diameter and a larger rear diameter. The smaller front diameter can be easily inserted into the opening of the tube, while the larger rear diameter gradually squeezes the opening. The guide rod automatically completes center positioning during the process of entering the tube, significantly reducing the difficulty of alignment.

[0035] The guide cone works in conjunction with the spatial multi-directional adaptive deflection mechanism: the guide cone first performs coarse alignment, and then the spatial multi-directional adaptive deflection mechanism performs adaptive angle fine adjustment. The two-stage linkage realizes the rapid and accurate coaxial alignment of the guide rod and the axis of the tubular object, improving the success rate of one-time push and place.

[0036] By utilizing the conical geometry of the guide cone, adaptive alignment can be achieved during the "entry-deepening" process, saving the steps of repeated observation and adjustment, simplifying the operation process, and shortening the operation time.

[0037] The limiting structure set on the guide rod directly blocks the slider or groove on the radial inner surface of the slip from moving forward, thereby precisely limiting the front limit position of the slip relative to the guide rod, preventing the slip from moving too far forward and disengaging from the clamping cone, and ensuring that the wedge clamping device is always in the effective working range.

[0038] The limit structure is a purely mechanical stop structure, which does not rely on sensors or additional power. It is simple and reliable, adaptable to the harsh environment of underground coal mines, and easy to maintain.

[0039] The salvage method of the present invention has the following advantages: 1. One-time precise compensation.

[0040] Before the tubular object is pushed into the borehole, the deviation from the borehole center can be observed and the displacement compensation of the ball joint can be completed. The joint can be locked immediately to avoid repeated adjustments due to narrow space or limited line of sight during the pushing and placing process, thereby shortening the operation time and reducing the risk.

[0041] 2. Two-stage alignment: "compensation first, then adaptive".

[0042] The rear ball joint compensates for overall offset, while the front ball joint adaptively fine-tunes the angle during the push-and-place process. The two-stage collaboration ensures the precise collinearity of the guide rod and the axis of the tubular object, significantly improving the alignment success rate, and is especially suitable for large-angle tilting conditions.

[0043] 3. The preload is adjustable and the state is controllable.

[0044] Adjusting the tightness of the front nut allows for adjustment of the rotational damping of the front ball joint, achieving the following: during the pushing and lowering process, the guide rod remains stable before entering the opening of the tubular object to be retrieved, preventing swaying; after entering the opening, the guide cone, under the constraint of the inner wall of the tubular object, drives the guide rod to self-adaptively deflect without manual intervention.

[0045] 4. Purely mechanical self-adaptation, requiring no additional power.

[0046] The entire process of alignment, contraction, expansion, and locking is completed through two actions: pushing and pulling. The device itself does not require hydraulic or electrical control components, has a simple structure, and high reliability, making it particularly suitable for damp, dusty, and explosive environments underground.

[0047] 5. Dual radial expansion locking ensures uniform gripping force.

[0048] The slip assembly expands uniformly under the triple action of the expansion spring force, the weight of the tubular object, and the friction of the inner wall. The slips are symmetrically arranged to increase the contact area, reduce damage to the tube wall, and provide sufficient locking force to prevent slippage.

[0049] 6. The operation is continuous, safe and efficient.

[0050] The entire process of "push-out → adaptive alignment → retraction → pull-back locking → drill-out" is completed smoothly, without the need for repeated drilling, reducing the dwell time in the hole, lowering the risk of hole collapse and drill jamming, and improving retrieval efficiency.

[0051] Furthermore, the sequence of steps in this invention ensures the continuity of alignment, locking, and lifting. Adjusting and compensating for locking the ball joint prevents angular drift during subsequent pushing and lowering processes. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of the adaptive deflection tubular object retrieval device for underground coal mines according to the present invention.

[0053] Figure 2 This is a schematic diagram of the structure of the adaptive deflection tubular object retrieval device for underground coal mines of the present invention when it enters the tubular object to be retrieved in the borehole.

[0054] Figure 3 This is a schematic diagram of the structure of the adaptive deflection tubular object retrieval device for underground coal mines of the present invention after it enters the tubular object to be retrieved in the borehole, wherein a wedge-tightening device located on the opposite front side enters the tubular object and wedges the inner wall of the tubular object.

[0055] Figure 4 This is a three-dimensional half-section diagram of the spatial multi-directional adaptive deflection mechanism 1.

[0056] Figure 5 This is a three-dimensional structural schematic diagram of the spatial multi-directional adaptive deflection mechanism 1.

[0057] Figure 6 This is a cross-sectional structural diagram of the locator assembly, with the cross-section perpendicular to the axis of the guide rod.

[0058] Figure 7 This is another cross-sectional view of the KAVO assembly, with the cross-section perpendicular to the guide rod axis.

[0059] Figure 8 This is a three-dimensional structural diagram of the present invention with both the front and rear nuts loosened.

[0060] Figure 9 This is a three-dimensional structural diagram of the present invention with both the front and rear nuts tightened. Detailed Implementation

[0061] Overall structure and methodology: The applicant's R&D team proposed a collaborative structure of "double ball joint connection system (front ball joint, rear ball joint, double ball joint rod) + guide rod 5 + slip assembly 6", as well as a sequential operation method of "first compensate for offset, then axial alignment, and finally radial locking".

[0062] like Figures 1 to 9 As shown, the present invention provides a tubular object retrieval device with adaptive deflection for use in underground coal mines, used to retrieve tubular objects 2 (such as drill rod sections, extraction pipe sections, etc.) in borehole 1, with the direction of penetration into borehole 1 as forward and the opposite direction as backward; including drill rod joint 3, spatial multi-directional adaptive deflection mechanism 4, guide rod 5 and slip assembly 6 for variable diameter locking; Drill pipe connector 3 is used to connect to an external drill pipe and is driven by the drill pipe; The rear end of the spatial multi-directional adaptive deflection mechanism 4 is rotatably connected to the front end of the drill pipe joint 3, which is used to align with the axis of the tubular object 2 and compensate for the offset distance of the tubular object 2 from the center of the borehole 1. The spatial multi-directional adaptive deflection mechanism 4 is rotatably connected to the guide rod 5. The guide rod 5 is provided with a clamping cone 7 that is smaller at the back and larger at the front. The clamping component 6 is sleeved on the clamping cone 7 and is used to adaptively change the diameter and lock the pipe wall when it is pulled back after entering the inside of the tubular object 2.

[0063] The spatial multi-directional adaptive deflection mechanism 4 forms a double-hinge structure through two rotating connections: the rear end is connected to the drill pipe joint 3, and the front end is connected to the guide rod 5. This allows for one-time compensation of the offset distance of the tubular object 2 from the center of the drill hole 1 before it is pushed into the hole, and achieves spatial multi-directional adaptive alignment during the process of entering the tubular object 2. This solves the problem that traditional fixed-angle mechanisms cannot cope with large-angle tilts.

[0064] The rear small and front large clamping cone 7 of the guide rod 5 forms a wedge surface fit with the slip assembly 6: when pushed out, the slip assembly 6 slides backward along the cone and contracts radially, which facilitates the entry of the tubular object 2; when pulled back, the slip assembly 6 slides forward along the cone and expands radially, generating self-increasing force to lock, realizing powerless adaptive variable diameter locking, with simple structure and high reliability.

[0065] The slip assembly 6 is fitted onto the tapered part of the guide rod 5. It can contract during the "forward" movement (when the tubular object 2 moves forward, the slip assembly 6 makes a relative backward displacement relative to the guide rod 5, and the diameter of the clamping tapered part 7 it contacts is smaller) and expand during the "reverse" movement (the diameter of the clamping tapered part 7 it contacts is larger). The locking force increases with the increase of the pull-back load, ensuring uniform and firm gripping of the inner wall of the tubular object 2 and reducing damage to the pipe wall.

[0066] The drill pipe joint 3—spatial multi-directional adaptive deflection mechanism 4—guide rod 5—slip assembly 6 are sequentially mechanically connected, which can realize the overall modular connection. It can directly replace the existing lower end tool of the drill pipe without modifying the drilling rig system. It is convenient to install, disassemble and maintain, and adapts to the complex working conditions in coal mines.

[0067] The spatial multi-directional adaptive deflection mechanism 4 includes a double ball joint rod body 8, a rear ball seat 9 at the rear end of the double ball joint rod body 8, a rear ball head 10 rotatably assembled inside the rear ball seat 9, and the rear ball head 10 and the rear ball seat 9 form a rear ball joint 11; the rear ball head 10 is fixedly connected to the front end of the drill pipe joint 3, and a rotational fit is formed between the drill pipe joint 3 and the rear ball seat 9. The front end of the double ball joint rod body 8 is provided with a front ball seat 12, and a front ball head 13 is rotatably assembled inside the front ball seat 12. The front ball seat 12 and the front ball head 13 form a front ball joint 14. The front ball head 13 is fixedly connected to the rear end of the guide rod 5, forming a rotational fit between the guide rod 5 and the front ball seat 12. Both the front ball seat 12 and the rear ball seat 9 have external threads on their outer circumferential surfaces. The front ball seat 12 is screwed with a front nut 15, and the rear ball seat 9 is screwed with a rear nut 16. The front nut 15 is used to balance the stability of the push-out posture and the adaptive deflection after entering the tubular object 2 by adjusting the tightness (thereby adjusting the rotational damping force between the front ball seat 12 and the front ball head 13). The rear nut 16 is used to prevent the angle between the drill pipe joint 3 and the double ball joint rod 8 from changing during the push-out process by tightening it.

[0068] The "tandem ball joint" structure of double ball joint body 8 + front ball joint 14 + rear ball joint 11 has two advantages: ① The "rear ball head 10 - rear ball seat 9" rotating pair of the rear ball joint 11 allows for one-time pre-adjustment of the angle before being pushed into the hole. The radial offset is compensated by the swing of the double ball joint rod to compensate for the offset distance of the tubular object 2 from the center of the borehole 1. ②The “front ball head 13-front ball seat 12” rotating pair of the front ball joint 14 continues to self-adaptively fine-tune during the pushing and releasing process, realizing multi-directional spatial alignment and significantly expanding the range of tilt angles that can be retrieved.

[0069] The integrated thread-locking design of the front nut 15 / rear nut 16 has two advantages: ① The front nut 15 can be tightened to make fine and continuous adjustment of the rotational damping force between the front ball seat 12 and the front ball head 13, so that the guide rod 5 can maintain a stable posture before being pushed into the pipe opening and can be flexibly deflected after entering the pipe opening, taking into account both "stability" and "flexibility". ② After tightening the rear nut 16, the relative angle of "drill pipe joint 3-double ball hinge rod body 8" is locked to prevent accidental rotation during the pushing and releasing process, which would cause compensation failure and improve the reliability of the operation.

[0070] The angle locking or resistance adjustment or unlocking can be achieved purely mechanically without external drive by simply tightening, adjusting or loosening the front nut 15 and the rear nut 16. It requires no hydraulic or electronic control system, has a compact structure and is easy to maintain, and is especially suitable for the humid and explosive environment of underground coal mines.

[0071] The front ball joint 14 and the front nut 15 correspond to the "alignment" function, while the rear ball joint 11 and the rear nut 16 correspond to the "offset compensation" function. The "alignment" and "offset compensation" functions are separated, resulting in a simple structure and independent adjustment.

[0072] The slip assembly 6 includes at least one pair of slips 17. The outer surface of each slip 17 is an arc-shaped surface 18, and the radially inner surface of each slip 17 is provided with a radially protruding slider 19 or a radially recessed groove 20. The two slips 17 in the pair are symmetrically distributed about the axis of the guide rod 5. The axial cross section of each slip 17 is as follows: Figures 1 to 3 The figure shown is wedge-shaped.

[0073] The radial outer surface of the clamping cone 7 of the guide rod 5 is provided with a groove 20 or a slider 19 that corresponds to and is adapted to the slider 19 or the groove 20. The slider 19 is slidably engaged in the groove 20 to ensure that the slip 17 is in close contact with the radial outer surface of the clamping cone 7 when it moves forward or backward relative to the guide rod 5, so that the relative forward and backward processes of the slip 17 relative to the guide rod 5 correspond to the opening and closing processes of the slip 17, respectively.

[0074] The radial inner surface of the slip 17 is provided with a slider 19 / slide groove 20, which forms a circumferential limiting sliding pair with the corresponding slide groove 20 / slider 19 on the outer surface of the clamping cone 7 of the guide rod 5. This ensures that the slip 17 is always in close contact with the outer surface of the cone throughout the entire "forward-backward" movement, without rotation or lateral displacement, thus improving motion stability.

[0075] The circumferentially limiting sliding pair also prevents the slip 17 from leaving the clamping cone 7 of the guide rod 5, so that the relative sliding of the slider 19 in the groove 20 is directly converted into the radial displacement of the slip 17 along the clamping cone 7: When the slip 17 retracts relative to the guide rod 5, the slip 17 slides toward the small end of the clamping cone 7, and the slip 17 retracts to enter the opening of the tube 2.

[0076] When the slip 17 moves forward relative to the guide rod 5, the slip 17 slides along the tapered part 7 (smaller at the back and larger at the front) towards the larger end to achieve opening and locking. At this time, the tubular object 2 can be pulled back out of the drill hole 1. The opening and closing actions of the Kava 17 only need to be strictly matched with the pushing and pulling processes, without the need for additional drive. It has a simple structure, rapid response, and achieves wedge tightening when the drilling rig pulls back and loosening when the pushing device is released. The action is reliable and simplifies the operation process.

[0077] The circumferentially distributed structure (symmetrical structure) of slider 19-slide groove 20 ensures that the arc-shaped surface 18 of each slip 17 fits evenly against the inner wall of the tubular object 2, resulting in a balanced distribution of locking force, reducing local indentations and wear, and improving gripping reliability and tube wall life.

[0078] The clamping cone 7 and the corresponding slip assembly 6 form a pair of wedge clamping devices. Two sets of wedge clamping devices are provided at intervals on the guide rod 5. The guide rod 5 around the small-diameter end of the clamping cone 7 forms a step 21. An expansion spring is provided between the step 21 corresponding to each wedge clamping device and the slip assembly 6 on the corresponding clamping cone 7. The expansion spring is a conventional part and is not shown in the figure. The cone angle of the clamping cone 7 is preferably 10°–30°.

[0079] Two sets of wedge clamping devices are arranged at intervals, forming a "double wedge clamping" structure on the guide rod 5. This creates two independent radial locking zones between the slip assembly 6 and the inner wall of the tubular object 2, resulting in a more uniform distribution of the locking force along the axial direction and significantly reducing the risk of single-point slippage.

[0080] An expansion spring is placed between the step 21 and the slip assembly 6, always providing the slip assembly with a force that can overcome resistance and move forward relative to the clamping cone. Even when fishing in an upward-sloping borehole, the slip assembly 6 can be pushed forward relative to the clamping cone 7 and open radially, achieving "zero-delay" wedge locking and improving response speed and locking reliability.

[0081] Both sets of wedge clamping devices rely on the wedge surface geometry of the clamping cone 7 and the expansion spring to form a double self-amplifying force effect: the greater the pull-back load, the greater the radial locking force. No external power is required, and the structure is simple and highly adaptable.

[0082] The front end of the guide rod 5 is provided with a guide cone 22 that is smaller at the front and larger at the back. The guide cone 22 is used to make it easier for the guide rod 5 to enter the opening of the tube 2 and to force the axes of the two to self-align during the process of the guide rod 5 entering the tube 2.

[0083] The guide cone 22 adopts a streamlined shape with a smaller front diameter and a larger rear diameter. The smaller front diameter can be easily inserted into the opening of the tube 2, while the larger rear diameter gradually squeezes the opening. The center positioning is automatically completed during the process of the guide rod 5 entering the tube 2, which significantly reduces the difficulty of alignment.

[0084] The guide cone 22 works in conjunction with the spatial multi-directional adaptive deflection mechanism 4: the guide cone 22 first performs coarse alignment, and then the spatial multi-directional adaptive deflection mechanism 4 performs adaptive angle fine adjustment. The two-stage linkage realizes the rapid and accurate coaxial alignment of the guide rod 5 and the axis of the tubular object 2, improving the success rate of one-time push and release.

[0085] By utilizing the cone (sloping) geometry of the guide cone 22, adaptive alignment can be completed during the "entry-deepening" process, saving the steps of repeated observation and adjustment, simplifying the operation process, and shortening the operation time.

[0086] The curved surface 18 of the locking mechanism 17 has anti-slip textures to increase the coefficient of friction with the inner wall of the tubular object 2. The anti-slip textures improve locking reliability and prevent slippage; the anti-slip textures can be serrated, diamond-shaped, or knurled, which are conventional techniques and are not shown in the figure.

[0087] The front end (i.e., lower end) of the slider 19 or slide groove 20 disposed on the guide rod 5 is provided with a limiting structure. The limiting structure is used to limit the front (lower) limit position of the slider 19 or slide groove 20 disposed on the radial inner surface of the slip 17 relative to the guide rod 5. The limiting structure can be an integrally disposed limiting block or a screw-connected limiting block, or a retaining ring or retaining spring fixed by screws. These are all existing structures and are not shown in the figure.

[0088] The limiting structure set on the guide rod 5 directly blocks the slider 19 or the groove 20 on the radial inner surface of the slip 17 from continuing to move forward, thereby precisely limiting the front limit position of the slip 17 relative to the guide rod 5, preventing the slip 17 from moving too far forward and disengaging from the clamping cone 7, and ensuring that the wedge clamping device is always in the effective working range.

[0089] The limit structure is a purely mechanical stop structure, which does not rely on sensors or additional power. It is simple and reliable, adaptable to the harsh environment of underground coal mines, and easy to maintain.

[0090] The present invention also discloses a corresponding salvage method, which utilizes the above-mentioned adaptive deflection tubular object salvage device for underground coal mines and proceeds according to the following steps: Before use, connect the upper end of the drill pipe connector 3 to the drill pipe; the drill pipe connector 3 and the rear ball joint 11 are integrally set or fixedly connected.

[0091] S1. The offset distance of the compensating tubular object 2 from the center of borehole 1: S1.1 Observation offset: Observe (visually or through camera) the position of the upper end of the tubular object 2 that fell into the borehole 1 relative to the center of the borehole 1, and obtain the offset distance information of the tubular object 2 from the center of the borehole 1; S1.2 Adjustment and Compensation: Adjust the rear ball joint 11 by using the displacement generated by the relative swing of the double ball joint rod 8 to compensate for the offset distance of the tubular object 2 from the center of the borehole 1. After the adjustment is completed, tighten the rear nut 16 of the rear ball joint 11 to lock the rear ball joint 11. S2. Adjust the front ball joint 14: Rotate the front nut 15 of the front ball joint 14 to adjust the preload of the front ball joint 14 to adjust its rotational damping force so that the guide rod 5 can maintain a stable posture when it is not subjected to external force and can adaptively deflect under the constraint of the inner wall of the tubular object 2. S3. Pushing and Adaptive Adjustment: The operator operates the drilling rig and pushes the adaptive deflection tubular retrieval device for underground coal mines into the borehole through the drill rod; because the compensation was made in advance in S1, the tip of the guide rod 5 enters the upper end of the tubular object 2 after being pushed into the hole. The restrictive effect of the inner wall of the tubular object 2 forces the front ball joint 14 to rotate adaptively, thereby achieving adaptive deflection and aligning the axis of the guide rod 5 with the axis of the tubular object 2. As the guide rod 5 goes deeper, the slip assembly 6 slides upward along the clamping cone 7 and contracts radially under the squeezing action of the inner wall of the tubular object 2, compressing the expansion spring in the process.

[0092] S4. Pull-back retrieval: The operator operates the drilling rig to pull out the adaptive deflection tubular object retrieval device used in underground coal mines. Under the combined action of the gravity of the tubular object 2, the friction of the inner wall, and the release force of the expansion spring, the slip assembly 6 slides downward relative to the guide rod 5 along the clamping cone 7 and expands radially, so that the arc surface 18 of the slip assembly 6 tightly fits the inner wall of the tubular object 2, achieving radial locking, so that the retrieved tubular object 2 is pulled out of the borehole 1 together with the adaptive deflection tubular object retrieval device used in underground coal mines.

[0093] The salvage method of the present invention has the following advantages: 1. One-time precise compensation.

[0094] The deviation of the tubular object 2 from the center of the borehole 1 is observed in advance and the displacement compensation of the ball joint 11 is completed. The joint is then locked immediately to avoid repeated adjustments due to narrow space or limited line of sight during the pushing and placing process, thereby shortening the operation time and reducing the risk.

[0095] 2. Two-stage alignment: "compensation first, then adaptive".

[0096] The rear ball joint 11 compensates for the overall offset, while the front ball joint 14 makes adaptive fine adjustments to the minute angles during the pushing and placing process. The two-stage collaboration ensures the precise collinearity of the guide rod 5 and the axis of the tubular object 2, significantly improving the alignment success rate, and is especially suitable for large-angle tilting conditions.

[0097] 3. The preload is adjustable and the state is controllable.

[0098] By adjusting the tightness of the front nut, the rotational damping of the front ball joint can be adjusted, thus achieving the following: during the pushing and placing process, the guide rod 5 remains stable before entering the opening of the tubular object 2 to be retrieved, preventing shaking; the guide cone 22 entering the opening drives the guide rod 5 to self-adaptively deflect under the constraint of the inner wall of the tubular object 2, without the need for manual intervention.

[0099] 4. Purely mechanical self-adaptation, requiring no additional power.

[0100] The entire process of alignment, contraction, expansion, and locking is completed through two actions: pushing and pulling. The device itself does not require hydraulic or electrical control components, has a simple structure, and high reliability, making it particularly suitable for damp, dusty, and explosive environments underground.

[0101] 5. Dual radial expansion locking ensures uniform gripping force.

[0102] The slip assembly 6 expands uniformly under the triple action of the expansion spring force, the gravity of the tubular object 2, and the friction of the inner wall. The slips 17 are symmetrically arranged to increase the contact area, reduce damage to the tube wall, and provide sufficient locking force to prevent slippage.

[0103] 6. The operation is continuous, safe and efficient.

[0104] The entire process of "push-out → adaptive alignment → retraction → pull-back locking → drill-out" is completed smoothly, without the need for repeated drilling, reducing the dwell time in the hole, lowering the risk of hole collapse and drill jamming, and improving retrieval efficiency.

[0105] Furthermore, the sequence of steps in this invention ensures the continuity of alignment, locking, and pull-back. Adjusting and compensating for locking the ball joint 11 prevents angular drift during subsequent pushing and releasing processes.

[0106] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A tubular object retrieval device for retrieving tubular objects from a borehole, wherein the direction of penetration into the borehole is defined as forward and the opposite direction as backward; Its features are: Includes drill pipe joints, spatial multi-directional adaptive deflection mechanism, guide rods, and slip assembly for variable diameter locking; The drill pipe joint is used to connect to an external drill pipe and is driven by the drill pipe. The rear end of the spatial multi-directional adaptive deflection mechanism is rotatably connected to the front end of the drill pipe joint, which is used to align with the axis of the tubular object and compensate for the offset distance of the tubular object from the center of the borehole. The spatial multi-directional adaptive deflection mechanism is rotatably connected to the guide rod in the forward direction. The guide rod is provided with a clamping cone that is smaller at the back and larger at the front. The clamping slip assembly is sleeved on the clamping cone and is used to adaptively change the diameter and lock the tube wall when it is pulled back after entering the tube.

2. The adaptive deflection tubular object retrieval device for underground coal mines according to claim 1, characterized in that: The spatial multi-directional adaptive deflection mechanism includes a double ball joint rod body, a rear ball seat at the rear end of the double ball joint rod body, a rear ball head rotatably assembled inside the rear ball seat, and the rear ball head and the rear ball seat forming a rear ball joint; the rear ball head is fixedly connected to the front end of the drill pipe joint, forming a rotational fit between the drill pipe joint and the rear ball seat; The front end of the double ball joint rod is provided with a front ball seat, and a front ball head is rotatably assembled inside the front ball seat. The front ball seat and the front ball head form a front ball joint; the front ball head is fixedly connected to the rear end of the guide rod, forming a rotational fit between the guide rod and the front ball seat. Both the front ball seat and the rear ball seat have external threads on their circumferential outer surfaces. The front ball seat is screwed with a front nut, and the rear ball seat is screwed with a rear nut. The front nut is used to balance stability of the push-out posture and adaptive deflection after entering the tubular object by adjusting the tightness. The rear nut is used to prevent angular changes between the drill pipe joint and the double ball joint during the push-out process by tightening it.

3. The adaptive deflection tubular object retrieval device for underground coal mines according to claim 2, characterized in that: The slip assembly includes at least one pair of slips, the outer surface of which is an arc-shaped surface, and the radial inner surface of which is provided with a radially protruding slider or a radially recessed groove; the two slips in the pair are symmetrically distributed about the axis of the guide rod. The radial outer surface of the clamping cone of the guide rod is provided with a groove or slider that corresponds to and is adapted to the slider or groove. The slider is slidably engaged in the groove to ensure that the slip is in close contact with the radial outer surface of the clamping cone when it moves forward or backward relative to the guide rod, so that the relative forward and backward processes of the slip relative to the guide rod correspond to the opening and contraction processes of the slip, respectively.

4. The adaptive deflection tubular object retrieval device for underground coal mines according to claim 3, characterized in that: The clamping cone and the corresponding slip assembly form a pair of wedge clamping devices. Two sets of wedge clamping devices are provided at intervals on the guide rod. The guide rod around the small diameter end of the clamping cone forms a step, and an expansion spring is provided between the step corresponding to each wedge clamping device and the slip assembly on the corresponding clamping cone.

5. The adaptive deflection tubular object retrieval device for underground coal mines according to any one of claims 1 to 4, characterized in that: The front end of the guide rod is provided with a guide cone that is smaller at the front and larger at the back. The guide cone is used to make it easy for the guide rod to enter the opening of the tube and to force the axes of the two to self-align during the process of the guide rod entering the tube.

6. The adaptive deflection tubular object retrieval device for underground coal mines according to claim 4, characterized in that: The curved surface of the kava has anti-slip textures to increase the coefficient of friction with the inner wall of the tube.

7. The adaptive deflection tubular object retrieval device for underground coal mines according to claim 4, characterized in that: The front end of the slider or groove set on the guide rod is provided with a limiting structure, which is used to limit the front limit position of the slider or groove set on the radial inner surface of the slip relative to the guide rod.

8. A salvage method, characterized in that: The following steps are performed using the adaptive deflection tubular object retrieval device for underground coal mines as described in any one of claims 1–7: Before use, connect the upper end of the drill pipe connector to the drill pipe; the drill pipe connector and the rear ball joint are integrally set or fixedly connected. S1. Compensation for the offset distance of the tubular object from the borehole center: S1.1 Observation offset: Observe (visually or through camera) the position of the upper end of the tubular object that fell into the borehole relative to the center of the borehole, and obtain the offset distance information of the tubular object from the center of the borehole; S1.2 Adjustment and Compensation: Adjust the rear ball joint by using the displacement generated by the relative swing of the double ball joint rods to compensate for the offset distance of the tubular object from the borehole center. After adjustment, tighten the rear nut of the rear ball joint to lock the rear ball joint. S2. Adjust the front ball joint: Rotate the front nut of the front ball joint to adjust the preload on the front ball joint to adjust its rotational damping force so that the guide rod can maintain a stable posture when it is not subjected to external force and can adaptively deflect under the constraint of the inner wall of the tubular object. S3. Pushing and Adaptive Adjustment: The operator uses the drilling rig to push the adaptive deflection tubular retrieval device for underground coal mines into the borehole through the drill rod; because the compensation was made in advance in S1, the tip of the guide rod enters the upper end of the tubular object after being pushed. The constricting effect of the inner wall of the tubular structure forces the front ball joint to rotate adaptively, thereby achieving adaptive deflection and aligning the axis of the guide rod with the axis of the tubular structure. As the guide rod goes deeper, the locking assembly slides upward along the locking cone and contracts radially under the squeezing action of the inner wall of the tube, compressing the expansion spring in the process; S4. Pull-back retrieval: The operator uses the drilling rig to pull out the self-adaptive deflection tubular retrieval device used in underground coal mines. Under the combined action of the weight of the tubular object, the friction of the inner wall, and the release force of the expansion spring, the slip assembly slides downward relative to the guide rod along the clamping cone and expands radially, so that the arc-shaped surface of the slip assembly tightly fits the inner wall of the tubular object, achieving radial locking. This allows the retrieval of the tubular object to be pulled out of the borehole along with the self-adaptive deflection tubular retrieval device used in underground coal mines.

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