Thread locking connection method for driving drill rod

Abstract

The invention relates to a thread locking connection method for an active drill rod, and belongs to the technical field of drilling machine active drill rod connection. The method comprises the steps that internal threads are arranged at one end of a drill rod body, and external threads matched with the internal threads of the drill rod body are arranged at one end of a drill rod connector; the method comprises the following steps: constructing a thread theoretical clearance volume model according to a set thread structure of a drill rod main body and a drill rod joint, and determining the optimal filling amount of a thread locking agent in the thread structure through a self-adaptive optimization iterative algorithm based on the model; and taking the thread locking agent with the dosage corresponding to the optimal filling amount, smearing the thread locking agent on an external thread of the drill rod joint, screwing the drill rod joint into the drill rod main body, and realizing thread locking connection between the drill rod main body and the drill rod joint after the thread locking agent is cured. According to the drill rod, the drill rod body and the drill rod connector can be independently detached, damaged parts can be independently replaced, meanwhile, the connection strength of the drill rod is large, the problem of leakage of drilling fluid can be avoided, and the stability and safety of drilling operation are powerfully guaranteed.

Description

Technical Field

[0001] The present invention belongs to the fields of mechanical design and artificial intelligence, relates to an active drill rod of a coal mine drill, and particularly relates to a threaded locking connection method for the active drill rod. Background Art

[0002] Currently, there are two main connection methods used between the drill pipe body and the drill pipe joint: welding connection and pin connection.

[0003] The welded connection between the drill pipe body and the drill pipe joint is achieved by melting the welding material at high temperatures and fusing it with the drill pipe matrix, thereby achieving a secure bond between the two, as shown in patent applications No. 2023104577279 and No. 2021201586254. Advantageously, the welded connection allows the drill pipe body and joint to form a solid, integrated structure, effectively enhancing load transfer capacity and providing outstanding stability under complex drilling conditions. Furthermore, the weld provides excellent sealing performance, effectively preventing drilling fluid leakage and ensuring safe drilling operations. However, this connection method has significant disadvantages. After welding, the drill pipe body and joint are difficult to disassemble, requiring destructive methods such as flame cutting and mechanical grinding to separate the components during maintenance, resulting in inefficient assembly and disassembly. Furthermore, the welded area is a stress concentration area, susceptible to localized wear due to long-term torsional and impact loads. Because damaged components cannot be individually disassembled, even if only a localized failure occurs, the entire drill pipe must be replaced, resulting in high replacement costs.

[0004] The pin connection between the drill pipe body and the drill pipe joint is achieved by inserting pins into corresponding holes in the drill pipe body and joint, thereby mechanically securing the two. This is illustrated in patent applications No. 2022207964845 and No. 2020101118720. Pin connections offer significant advantages in terms of removability. When replacing joints or repairing the drill pipe, simply pull out the pin to separate the body and joint. This simple and quick operation significantly improves the efficiency of drill pipe component replacement and effectively reduces maintenance time and costs. However, this connection method also has significant drawbacks. Regarding sealing, the pin and the pin hole cannot form a tight fit, which can easily lead to gaps, causing drilling fluid leakage and compressing the safety and stability of drilling operations. Regarding connection strength, pin connections rely primarily on the pins to withstand shear and compressive forces to transmit loads. Compared to welding and other methods, their overall connection strength is lower. When subjected to high torque or axial forces, the pins may deform or break, causing the drill pipe connection to fail.

[0005] In summary, the existing connection methods used between the drill pipe body and the drill pipe joint either have low assembly and disassembly efficiency and high replacement cost, or have poor connection strength and insufficient sealing, which makes it difficult to meet the efficiency and safety requirements of underground coal mines. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a threaded locking connection method for an active drill rod to solve the problems of low assembly and disassembly efficiency, high replacement cost, poor connection strength and insufficient sealing in the connection method between the drill rod body and the drill rod joint.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A thread locking connection method for an active drill rod, the active drill rod comprising a drill rod body and a drill rod joint, characterized in that the method comprises: providing an internal thread at one end of the drill rod body, and providing an external thread matching the internal thread of the drill rod body at one end of the drill rod joint; constructing a theoretical thread gap volume model according to the thread structures of the drill rod body and the drill rod joint, and determining the optimal filling amount of a thread locking agent in the thread structure through an adaptive optimization iterative algorithm based on the model; taking a dose of thread locking agent corresponding to the optimal filling amount and applying it to the external thread of the drill rod joint, then screwing the drill rod joint into the drill rod body, and achieving a thread locking connection between the drill rod body and the drill rod joint after the thread locking agent solidifies.

[0009] Furthermore, the thread gap between the drill pipe body and the drill pipe joint is equivalent to the combined space of "annular cylinder + tooth profile gap", and the theoretical thread gap volume model is constructed:

[0010]

[0011] Where, d in d is the internal thread diameter of the drill pipe body, out is the major diameter of the external thread of the drill pipe joint, P is the pitch, h is the tooth profile height, and L is the screw-in length.

[0012] Furthermore, considering the wetting and diffusion characteristics of the locking agent, the wetting coefficient k is introduced to correct the theoretical prefill volume V 预填 =kV 理论 .

[0013] Furthermore, the optimal filling amount of the threadlocker is determined by an adaptive optimization iterative algorithm, including:

[0014] Theoretical prefilling volume V 预填 As the initial value, set the optimization range [0.8V 理论 ,1.2V 理论 ], iteratively optimized by a spiral search strategy;

[0015] Each iteration generates a candidate filling volume V 候选 , and the candidate filling amount V 候选 Corresponding actual disassembly torque T 实测 , spillover risk λ;

[0016] The candidate filling amount V 候选 -Actual disassembly torque T 实测 - Overflow risk λ" data is input into BP neural network for training, the network model deviation is corrected, and then the BP neural network outputs the iterative optimization filling amount V 迭代 ;

[0017] Repeat the iteration until the output of the BP neural network meets the convergence condition, and the iterative optimization filling amount V output by the BP neural network when the convergence condition is met is 迭代 As the optimal filling amount.

[0018] Furthermore, in each iteration, the BP neural network outputs the predicted torque T 预测 and predicted spillover risk λ 预测 , by minimizing the loss function |T 预测 -T 实测 |+βλ 预测 Train the BP neural network, modify the network parameters, and iteratively optimize the filling volume V through the modified BP neural network output 迭代 , and the modified BP neural network is used for the next iteration; where β is the overflow penalty coefficient.

[0019] Furthermore, the convergence judgment conditions include: in three consecutive iterations, the filling amount V output by the BP neural network 迭代 The fluctuation is less than 0.5%, the deviation between the predicted disassembly torque and the measured torque is less than 3%, and the overflow risk λ 预测 <0.1%.

[0020] Furthermore, the thread locking agent adopts Loctite 271 thread locking agent.

[0021] The beneficial effects of the present invention are:

[0022] (1) Higher assembly and disassembly efficiency: Traditional welding connection methods form metallurgical bonds at the welded parts, making it difficult to disassemble the drill pipe body and the joint. Destructive methods such as flame cutting and mechanical grinding are required to separate them, which seriously affects the assembly and disassembly efficiency of the components. However, the present invention uses a thread locker bonding method, which can achieve rapid assembly and disassembly only through the rotary torque of the drill rig, without the need for destructive operations, greatly shortening the assembly and disassembly time and significantly improving the assembly and disassembly efficiency.

[0023] (2) Lower replacement costs: Traditional welded drill pipes have stress concentration problems in the weld area. When subjected to torsion and impact loads, fatigue cracks are easily generated at the weld. Due to the limitations of the overall welded structure, once local damage occurs, even if it is only a minor fault, the entire drill pipe must be replaced, resulting in high replacement costs. However, the drill pipe body and drill pipe joint connected by the threaded locking method proposed in the present invention can be disassembled independently. When the components are worn, the damaged parts can be replaced separately, greatly reducing maintenance and replacement costs. In addition, the present invention also determines the optimal filling amount of the thread locker through an adaptive optimization method, avoiding the problem of contaminating the drill pipe due to excessive overflow or affecting the locking effect due to insufficient dosage.

[0024] (3) Strong connection strength and good sealing: In the traditional pin connection method, it is difficult for the pin to fit tightly with the pin hole, which increases the risk of drilling fluid leakage and threatens the safety and stability of the drilling operation. In addition, the pin connection mainly relies on the pin to withstand shear force and extrusion force to transmit the load. The overall connection strength is low. When subjected to large torque or axial force, the pin is very likely to deform and break, resulting in failure of the drill pipe connection. Therefore, the present invention proposes the use of thread locking, and combined with the high-strength bonding properties of the thread locking agent, the thread locking agent is filled in the gap of the thread structure to make the threaded drill pipe connection stronger. At the same time, the locking agent can fill the thread gap to form a sealing layer, effectively avoiding the problem of drilling fluid leakage, and effectively ensuring the stability and safety of the drilling operation.

[0025] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 This is a schematic diagram of a threaded locking connection according to an embodiment of the present invention;

[0028] Figure 2 Schematic diagram of a flow chart of a method for determining the optimal filling amount of a thread locking agent according to an embodiment of the present invention.

[0029] Reference numerals: 1 - drill pipe body; 2 - external thread; 3 - drill pipe joint. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] Among them, the accompanying drawings are only for illustrative purposes and represent only schematic diagrams rather than actual pictures, and should not be understood as limiting the present invention. In order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the dimensions of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings.

[0032] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "back", etc. indicating directions or positional relationships, they are based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] In order to solve the problems of low assembly and disassembly efficiency, high replacement cost, poor connection strength and insufficient sealing in the connection method between the drill pipe body and the drill pipe joint, the present invention proposes a thread locking connection method for an active drill pipe. The method mainly comprises: bonding the drill pipe body and the drill pipe joint with a thread locker; and determining the optimal filling amount of the thread locker through an adaptive optimization method.

[0034] To this end, an embodiment of the present invention provides a thread locking connection method for an active drill rod, such as Figure 1 As shown, drill pipe body 1 and drill pipe joint 3 are threaded together. After applying threadlocker, external thread 2 is screwed into the corresponding internal thread of drill pipe body 1. The threadlocker fills the gaps between the threads and, after curing, forms a high-strength bond and locks the joint, achieving a sealed and locked connection between the drill pipe body and the drill pipe joint.

[0035] The connection method between the drill rod body 1 and the drill rod joint 3 is:

[0036] 1) Preparation: Confirm that there are no cracks, deformations or other defects on the surface of the drill pipe body 1 and the drill pipe joint 3; at the same time, prepare thread lockers and cleaning tools (wire brush, rag).

[0037] 2) Surface Cleaning: Use a wire brush to carefully clean the internal threads of the drill pipe body 1 and the external threads 2 of the drill pipe joint 3, removing impurities such as oil, rust, and sand. Ensure that the thread surfaces are clean and dry. This ensures that the threadlocker fully contacts the thread surface and achieves optimal results. After cleaning, wipe it clean with a clean rag.

[0038] 3) Apply thread locker: Apply the thread locker evenly on the external thread 2 of the drill pipe joint 3.

[0039] 4) Engage the threads: Align the drill pipe joint 3, coated with thread locker, with the internal threads of the drill pipe body 1 and slowly screw it in to ensure that the threads are properly engaged. During the screwing process, the coaxiality of the drill pipe body and the joint must be maintained to prevent damage to the threads due to excessive lateral force.

[0040] 5) Tighten and fix: Use a torque wrench to tighten the drill pipe joint 3 onto the drill pipe body 1 to complete the connection.

[0041] After the drill rod body 1 and the drill rod joint 3 are locked and connected according to the above connection method, the drill rod body 1 and the drill rod joint 3 can also be quickly separated.

[0042] The disassembly steps between the drill rod body 1 and the drill rod joint 3 are as follows:

[0043] 1) Preparation: Use the drill rig remote control to adjust the operating status and prepare for disassembly.

[0044] 2) Apply breakout torque: Use the remote control to adjust the drill head and gradually apply the breakout torque. During the application of the breakout torque, observe the condition of the drill pipe to avoid damage to the drill pipe due to excessive torque.

[0045] 3) Loosening the threads: As the breakout torque gradually increases, the bonding force of the thread locker is broken, and the threaded connection between the tool joint 3 and the drill pipe body 1 begins to loosen. Continue to rotate slowly to gradually unscrew the tool joint 3 from the drill pipe body 1.

[0046] 4) Taking out the drill rod joint: After the drill rod joint 3 is completely separated from the drill rod body 1, the drill rod joint 3 is taken out.

[0047] The threadlocker used in this embodiment is a one-component sealing adhesive, formulated based on the principle of oxygen's inhibition of free radicals, specifically designed for threaded connections. When the applied surface is isolated from air and catalytically activated, it rapidly polymerizes and cures at room temperature, forming a tough plastic film within the thread gaps, achieving locking.

[0048] Taking into account factors such as quick disassembly, bond strength, and disassembly torque, Loctite 271 threadlocker was selected as the adhesive between the drill pipe body 1 and the drill pipe joint 3. This red threadlocker has high strength, a viscosity of 500 mPa·s, and an average disassembly torque (thread contact torque) of 25 N·m.

[0049] In another embodiment of the present invention, a method for determining the optimal threadlocker filling amount based on adaptive optimization is provided to control the threadlocker filling amount to avoid contamination of the drill pipe due to excessive overflow or affecting the locking effect due to insufficient amount.

[0050] like Figure 2 As shown, the steps to determine the optimal filling amount of thread locker are as follows:

[0051] 1. Calculation of theoretical pre-filling volume

[0052] (1) Constructing a theoretical thread gap volume model: The thread gap between the drill pipe body and the drill pipe joint is equivalent to the combined space of "annular cylinder + tooth profile gap", and the theoretical thread gap volume model can be constructed:

[0053]

[0054] Where, d in The internal thread diameter of the drill pipe body 1, d out is the major diameter of the external thread of the drill pipe joint 3, P is the pitch, h is the tooth profile height, and L is the screw-in length.

[0055] (2) Correcting the initial filling volume: Considering the "wetting and diffusion" characteristics of the locking agent (the locking agent will penetrate into the thread gap due to surface tension), the wetting coefficient k (experimentally calibrated, range 0.8 to 1.2) is introduced to correct the theoretical pre-filling volume V 预填 :

[0056] V 预填 =kV 理论

[0057] 2. Adaptive optimization iteration

[0058] (1) Spiral search algorithm optimization: V 预填 As the initial value, set the optimization range [0.8V 理论 ,1.2V 理论 ], iteratively optimized by spiral search strategy:

[0059] Each iteration generates a candidate filling volume V 候选 , press V 候选 Apply thread locker to complete the drill pipe thread connection; after curing, test the disassembly torque T 实测 , overflow area S 溢出The overflow area is the area of ​​the thread locker that overflows from the thread gap to the drill pipe body and joint surface during the thread connection process.

[0060] (2) BP neural network correction: the candidate filling amount V 候选 -Measured torque T 实测 - Overflow risk λ" data is input into BP neural network and the output is predicted torque T 预测 and predicted spillover risk λ 预测 , among which, there is a positive correlation between the overflow risk and the overflow area, which can be calculated based on the measured overflow area S 溢出 After the overflow risk λ is obtained, it is input into the BP neural network. By minimizing the loss function |T 预测 -T 实测 |+βλ 预测 (β is the overflow penalty coefficient) to train the BP neural network, correct the network parameters, and output the corrected model after training. The filling amount V is iteratively optimized through the corrected BP neural network output 迭代 , and the modified BP neural network is used for the next iteration.

[0061] 3. Determination of the optimal filling amount of thread locker

[0062] (1) Convergence judgment conditions: In three consecutive iterations, the fluctuation of the filling amount output by the BP neural network is less than 0.5%, the deviation between the predicted disassembly torque and the measured torque is less than 3%, and the overflow risk λ 预测 <0.1%.

[0063] (2) Output the optimal solution: When the convergence condition is met, the filling amount V output by the BP neural network of the current iteration is 迭代 That is the optimal thread locker filling amount V 最优 .

[0064] In summary, the present invention proposes a threaded locking connection method for active drill pipes. This method connects the drill pipe body and the drill pipe joint via a threaded structure. A threadlocker is then filled between the threads of the drill pipe body and the drill pipe joint, forming a tough plastic film within the thread gap to achieve locking. Furthermore, an adaptive optimization method is used to determine the optimal amount of threadlocker to be filled, preventing contamination of the drill pipe due to excess overflow or compromise of the locking effect due to insufficient threadlocker.

[0065] Compared with traditional welding connection methods, the present invention adopts thread locking agent bonding, which can achieve rapid assembly and disassembly only through the rotational torque of the drill rig, without the need for destructive operations, greatly shortening the assembly and disassembly time. In addition, when the components are worn, the damaged parts can be replaced separately, reducing the maintenance and replacement costs.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A threaded locking connection method for an active drill rod, wherein the active drill rod comprises a drill rod body and a drill rod joint, characterized in that: The method comprises: setting an internal thread at one end of a drill pipe body and setting an external thread that matches the internal thread of the drill pipe body at one end of a drill pipe joint; constructing a theoretical thread gap volume model according to the thread structures of the drill pipe body and the drill pipe joint, and determining the optimal filling amount of a thread locking agent in the thread structure through an adaptive optimization iterative algorithm based on the model; taking a dose of thread locking agent corresponding to the optimal filling amount and applying it to the external thread of the drill pipe joint, then screwing the drill pipe joint into the drill pipe body, and achieving a threaded locking connection between the drill pipe body and the drill pipe joint after the thread locking agent is cured.

2. The method according to claim 1, characterized in that The thread clearance between the drill pipe body and the drill pipe joint is equivalent to the combined space of "annular cylinder + tooth profile gap" to construct the theoretical thread clearance volume model: Where, d in d is the internal thread diameter of the drill pipe body, out is the major diameter of the external thread of the drill pipe joint, P is the pitch, h is the tooth profile height, and L is the screw-in length.

3. The method according to claim 2, characterized in that Considering the wetting and diffusion characteristics of the locking agent, the wetting coefficient k is introduced to correct the theoretical pre-filling volume V 预填 =kV 理论 .

4. The method according to claim 3, characterized in that The optimal filling amount of the threadlocker is determined by an adaptive optimization iterative algorithm, including: 预填 As the initial value, set the optimization range [0.8V 理论 ,1.2V 理论 ], iteratively optimized by a spiral search strategy; Each iteration generates a candidate filling volume V 候选 , and the candidate filling amount V 候选 Corresponding actual disassembly torque T 实测 , spillover risk λ; The candidate filling amount V 候选 -Actual disassembly torque T 实测 - Overflow risk λ" data is input into BP neural network for training, the network model deviation is corrected, and then the BP neural network outputs the iterative optimization filling amount V 迭代 ; Repeat the iteration until the output of the BP neural network meets the convergence condition, and the iterative optimization filling amount V output by the BP neural network when the convergence condition is met is 迭代 As the optimal filling amount.

5. The method according to claim 4, characterized in that In each iteration, the BP neural network outputs the predicted torque T 预测 and predicted spillover risk λ 预测 , by minimizing the loss function |T 预测 -T 实测 |+βλ 预测 Train the BP neural network, modify the network parameters, and iteratively optimize the filling volume V through the modified BP neural network output 迭代 , and the modified BP neural network is used for the next iteration; where β is the overflow penalty coefficient.

6. The method according to claim 4, characterized in that Convergence judgment conditions include: in three consecutive iterations, the filling amount V output by the BP neural network is 迭代 The fluctuation is less than 0.5%, the deviation between the predicted disassembly torque and the measured torque is less than 3%, and the overflow risk λ 预测 <0.1%.

7. The method according to any one of claims 1 to 6, characterized in that The thread locker used is Loctite 271 thread locker.

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