An oil drill pipe thread detection device and detection method based on high-frequency eddy current

Abstract

The present invention discloses an oil drill pipe thread detection device and a detection method based on high-frequency eddy current, belonging to the technical field of non-destructive testing of drill pipes, and solving the problems of low detection accuracy and incomplete detection in the existing non-destructive testing methods for drill pipe threads; the oil drill pipe thread detection device based on high-frequency eddy current includes an outer thread scanning device for drill pipes and an inner thread scanning device for drill pipes; the outer thread scanning device for drill pipes includes an outer thread detection component and an outer thread fixing component; the inner thread scanning device for drill pipes includes an inner thread detection component and an inner thread fixing component; a plurality of high-frequency eddy current probes are arranged on both the outer thread detection component and the inner thread detection component, and the plurality of high-frequency eddy current probes are electrically connected to the detection system respectively. In the present invention, when scanning the outer thread of the drill pipe, the outer thread detection component and the outer thread fixing component are respectively clamped on both sides of the outer thread of the drill pipe, and the high-frequency eddy current probes on the outer thread detection component are used to comprehensively scan the outer thread of the drill pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive testing of drill pipes, and particularly to a thread detection device and method for oil drill pipes based on high-frequency eddy current. Background Art

[0002] Drill pipes play an important role in the exploration, development, and production of oil and gas. The threads at the end joints of drill pipes are used for connecting drill pipes to each other. These threads bear the working load of the drill pipes during their service life. Therefore, the detection of these threads is extremely important. Due to the extremely harsh working conditions of drill pipes during their service life, they are affected by the coupling of factors such as complex formation conditions, harsh corrosive media, fluid erosion, complex movements, and combined movement loads of tension, compression, bending, and torsion. After long-term use, drill pipe threads will cause various thread failure problems such as cracks at the root of drill pipe threads, broken threads, unthreading, corrosion, and taper changes in the thread area, which will further lead to major safety accidents such as connection failures during the service life of drill pipes.

[0003] Currently, the main detection techniques for threaded drill pipes include commonly used detection methods such as visual inspection, magnetic flux leakage detection, ultrasonic detection, and magnetic particle detection. Manual visual inspection is suitable for the detection of a small batch of drill pipe threads. Since small cracks in the threads are often filled and covered by oil stains, and the viewing angle of the female threads of drill pipes is limited, it is difficult to detect small cracks. Magnetic flux leakage detection requires magnetization of the drill pipe threads, and there are certain blind spots in both the magnetized part and the detected part, making it difficult to detect small cracks and resulting in low detection accuracy. Ultrasonic detection uses echoes to detect defects at the bottom of drill pipe threads. Although it can detect deeper defects, due to the complex structure of drill pipe threads, only some defects at the bottom can reflect ultrasonic waves back to the probe, resulting in a relatively high missed detection rate. Moreover, ultrasonic detection requires a coupling agent, which limits the detection efficiency to a certain extent. Magnetic particle detection has relatively high detection accuracy, but since imaging and defect observation still need to be completed manually, the efficiency is low.

[0004] In the Chinese invention patent with the authorization announcement number CN112114030B, a thread detection device and method for drill pipes based on ferrite eddy current thermal imaging are disclosed. In this patent, an infrared thermal imager is used to record the temperature changes on the surface of drill pipe threads, and then the temperature changes are used to judge the defect positions of drill pipes. Although this detection method has high detection efficiency, it requires deep cleaning of drill pipe threads before detection, and the detection equipment has high costs, a complex detection device, and it is difficult to detect the internal threads of drill pipes.

[0005] In the Chinese invention patent with the publication number CN112815857A, a thread detection device and method for drill pipes are disclosed. In this patent, the detection is mainly focused on the morphological parameters such as the tooth height, tooth width, pitch, taper, large end diameter, and cone length of the external threads of the phosphated drill pipes, and it cannot detect the thread defects of drill pipes.

[0006] In summary, the defects of drill pipe threads are often filled and covered with oil stains, making visual inspection difficult; the detection accuracy of ultrasonic testing and magnetic flux leakage testing is not high, and it is difficult to detect tiny defects, posing a great potential safety hazard. The eddy current thermal imaging detection method requires deep cleaning of the threads, and the detection device is complex, costly, and unable to detect internal threads. Therefore, it is of practical significance to develop a high-efficiency, high-precision, and low-cost detection device for drill pipe internal and external threads. Summary of the Invention

[0007] Aiming at the deficiencies in the prior art, the present invention provides an oil drill pipe thread detection device and detection method based on high-frequency eddy current, which solves the problems of low detection accuracy and incomplete detection in the existing non-destructive testing methods for drill pipe threads.

[0008] In the first aspect, in order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] An oil drill pipe thread detection device based on high-frequency eddy current includes an outer thread scanning device for drill pipe and an inner thread scanning device for drill pipe; a number of high-frequency eddy current probes are provided on both the outer thread scanning device for drill pipe and the inner thread scanning device for drill pipe, and the number of high-frequency eddy current probes are electrically connected to the detection system respectively; the outer thread scanning device for drill pipe is connected to the outer thread of the drill pipe and is used for scanning the defects of the outer thread of the drill pipe; the inner thread scanning device for drill pipe is connected to the inner thread of the drill pipe and is used for scanning the defects of the inner thread of the drill pipe.

[0010] Further, the outer thread scanning device for drill pipe includes a first skeleton ring, and an outer thread detection component and an outer thread fixing component are movably arranged on the first skeleton ring; the outer thread detection component and the outer thread fixing component are respectively clamped on both sides of the outer thread of the drill pipe;

[0011] The inner thread scanning device for drill pipe includes a second skeleton ring, and an inner thread detection component and an inner thread fixing component are movably arranged on the second skeleton ring; the inner thread detection component and the inner thread fixing component respectively abut against both sides of the inner thread of the drill pipe;

[0012] The high-frequency eddy current probes are arranged on the outer thread detection component and the inner thread detection component.

[0013] In this solution, when scanning the defects of the outer thread of the drill pipe, the outer thread detection component and the outer thread fixing component in the outer thread scanning device for drill pipe are respectively clamped on both sides of the outer thread of the drill pipe, and the high-frequency eddy current probes on the outer thread detection component are used to comprehensively scan the defects of the outer thread of the drill pipe; when scanning the defects of the inner thread of the drill pipe, the inner thread detection component and the inner thread fixing component in the inner thread scanning device for drill pipe respectively support on both sides of the inner thread of the drill pipe, and the high-frequency eddy current probes on the inner thread detection component are used to comprehensively scan the inner thread of the drill pipe, with high scanning accuracy and fast speed.

[0014] Further, the external thread detection assembly includes a detection block fixing bracket fixed to the inner side of the first skeleton ring; an external thread detection block is installed on the detection block fixing bracket, and threads are tapped on the side of the external thread detection block close to the external thread of the drill pipe, and a high-frequency eddy current probe is installed on the thread teeth of the external thread detection block;

[0015] The external thread fixing assembly includes a lifting adjustment cylinder and an external thread support block. The lifting adjustment cylinder is movably connected to the inner side of the first skeleton ring; the top of the external thread support block is inserted into the lifting adjustment cylinder, and the bolt on the side wall of the lifting adjustment cylinder fixes the external thread support block; threads are tapped on the side of the external thread support block close to the external thread of the drill pipe.

[0016] In this solution, the sides of the external thread detection block and the external thread support block with threads are respectively connected to both sides of the external thread of the drill pipe. During the detection process, the first skeleton ring is rotated, and the first skeleton ring drives the two to move along the external thread of the drill pipe, thereby comprehensively scanning the external thread of the drill pipe. The coverage area during the scanning is large, avoiding missing areas. The external thread support block can be axially adjusted up and down relative to the lifting adjustment cylinder, and its position can be flexibly adjusted and fixed when installing the external thread support block.

[0017] Further, a first slider is connected to the side of the detection block fixing bracket close to the lifting adjustment cylinder, and a first slide rail is connected to the side of the lifting adjustment cylinder close to the detection block fixing bracket. The first slider is slidably connected to the first slide rail;

[0018] A regulating rod is connected to the side of the lifting adjustment cylinder far from the detection block fixing bracket. The regulating rod is movably arranged in the chute of the first skeleton ring and is connected to the chute through a bolt;

[0019] Elastic band fixing ports are arranged on both the detection block fixing bracket and the external thread support block, and an elastic band is connected between the two elastic band fixing ports.

[0020] In this solution, since the position of the external thread of the drill pipe is conical, the distance between the external thread detection block and the external thread support block needs to be adjusted radially during each scanning process; during the scanning process, the external thread support block moves radially under the action of the tension of the elastic band, so that the external thread detection block always fits with the external thread of the drill pipe; the design of the first slider and the first slide rail can ensure the accuracy and stability of the radial movement.

[0021] Further, a circuit board accommodation groove is opened on the external thread detection block, and a circuit board cover is installed on the circuit board accommodation groove through screws; a wire routing groove is opened on one side of the circuit board accommodation groove, and a cable fastening cover is installed on the wire routing groove through screws.

[0022] In this solution, the probe circuit board is arranged in the circuit board accommodation groove, and the circuit board cover encapsulates the probe circuit board; the cable for connecting the probe circuit board passes through the wire routing groove, and the cable clamping cover can fix the cable to prevent the connection structure between the cable and the probe circuit board from being damaged when the externally threaded detection block is rotated.

[0023] Furthermore, the internal thread detection component includes a detection block fixing block, which is movably connected to the second skeleton ring; an internal thread detection block is installed on the detection block fixing block, and threads are tapped on the side of the internal thread detection block close to the internal thread of the drill pipe; high-frequency eddy current probes are installed on the threads of the internal thread detection block;

[0024] The internal thread fixing component includes an adjusting frame, which is connected to the second skeleton ring; an internal thread support block is connected to the bottom of the adjusting frame, and threads are tapped on the side of the internal thread support block close to the internal thread of the drill pipe.

[0025] In this solution, the internal thread detection block and the internal thread support block are respectively supported on both sides of the internal thread of the drill pipe. During detection, rotating the second skeleton ring drives the two to rotate, and the high-frequency eddy current probe on the internal thread detection block detects the internal thread of the drill pipe during rotation.

[0026] Furthermore, a second slide rail is connected to the side of the detection block fixing block close to the adjusting frame, and a second slide block is connected to the side of the adjusting frame close to the detection block fixing block; the second slide block is slidably connected to the second slide rail; a spring is arranged between the detection block fixing block and the internal thread support block;

[0027] The top of the second slide block is connected to the second skeleton ring through a rod.

[0028] In this solution, the spring drives the detection block fixing block to move radially along the direction of the second slide rail through elastic force, so that the internal thread detection block fits with the internal thread of the drill pipe to be measured.

[0029] Furthermore, the high-frequency eddy current probe includes two copper coils arranged side by side, and two ferrite cores are respectively fixed inside the two copper coils; the two copper coils are connected to the detection system through a bridge-type adjustment circuit.

[0030] In this solution, the two copper coils are connected to a bridge-type conditioning circuit. When there is a defect at the bottom of one of the coils, the impedance of the coil changes, and the balance of the bridge is broken, so that the scanned defect can be responded and output. The high-frequency eddy current probe composed of the copper coil and the ferrite core has higher spatial resolution; the ferrite core has high magnetic permeability, which can converge the magnetic induction lines generated by the copper coil to enhance the magnetic field generated by the copper coil and improve the eddy current detection sensitivity; the inductance of the copper coil is between 0.1 - 50 uH, the resistance is between 0.1 - 10 Ω, the L∶R ratio is high, and the excitation signal frequency range is between 100 kHz - 3 MHz.

[0031] Further, the detection system includes a probe circuit board, an eddy current detection circuit board, and a host computer. The probe circuit board is connected to the copper coil of the high-frequency eddy current probe through a bridge-type adjustment circuit; the eddy current detection circuit board is electrically connected to the probe circuit board, and the host computer is electrically connected to the eddy current detection circuit board;

[0032] The eddy current detection circuit board includes a pre-stage circuit, a system-on-chip circuit, and an alarm unit connected in sequence; the pre-stage circuit is electrically connected to the probe circuit board, and the system-on-chip circuit is electrically connected to the host computer.

[0033] In this solution, the pre-stage circuit processes the excitation signal and the eddy current signal; the system-on-chip circuit controls the entire circuit board, can generate excitation signals with different waveforms, amplitudes, and frequencies, obtains the real and imaginary parts of the induction signal through the collected voltage signal, and then analyzes to obtain the required impedance change signal and sends it to the host computer.

[0034] In a second aspect, based on the high-frequency eddy current-based oil drill pipe thread detection device provided in the first aspect, the present invention provides a high-frequency eddy current-based oil drill pipe thread detection method, including the following steps:

[0035] Step 1: Connect the probe circuit board and the eddy current detection circuit board;

[0036] Step 2: Install a drill pipe external thread scanning device or a drill pipe internal thread scanning device on the drill pipe;

[0037] Step 3: Set the alarm threshold of the alarm unit and the parameters of the high-frequency eddy current probe in the host computer; after aligning the high-frequency eddy current probe with the defect-free thread position on the drill pipe, click to set the balance center;

[0038] Step 4: Start the detection program, rotate the drill pipe external thread scanning device or the drill pipe internal thread scanning device to start scanning. When the high-frequency eddy current probe detects a defect signal, the system-on-chip circuit controls the alarm unit to alarm;

[0039] Step 5: After the scanning is completed, remove the drill pipe external thread scanning device or the drill pipe internal thread scanning device, export the detection data by the host computer and perform scanning data processing, and the detection ends.

[0040] The beneficial effects of the present invention are:

[0041] In the high-frequency eddy current-based oil drill pipe thread detection device provided by the present invention, when detecting the external thread, the external thread detection block and the external thread support block are clamped on both sides of the drill pipe external thread, and the first skeleton ring drives the two to rotate one week. During the rotation, the high-frequency eddy current probe on the external thread detection block scans the drill pipe external thread. The scanning efficiency is high, the scanning range is wide, and there will be no missed dead corners.

[0042] The detection accuracy of the high-frequency eddy current probe is high; a ferrite with high magnetic permeability is inserted into the copper coil. The ferrite has a high magnetic permeability to converge the magnetic field, making the magnetic field generated by the coil stronger, increasing the inductance of the coil. The copper coil with a larger diameter can reduce the coil resistance and improve the quality factor of the coil. The copper coil has a small aperture and higher spatial resolution. The high-frequency excitation signal enhances the skin effect of the eddy current, and the differential coil design can improve the detection sensitivity and reduce the lift-off effect. This detection method can detect tiny defects on the thread surface. The detection efficiency of the high-frequency eddy current probe is high; compared with the traditional drill pipe thread detection device, high-frequency eddy current detection can be completed in a very short time, does not require a coupling agent, realizes non-contact measurement, and will not affect the thread surface and cause no pollution to the environment. The designed external thread detection block and internal thread detection block both contain 16 high-precision high-frequency eddy current probes, which can simultaneously scan 16 thread positions, output 16-channel data, and realize the efficient scanning of the oil drill pipe thread.

[0043] The internal and external thread detection of the female and male threads of the oil drill pipe is realized. The drill pipe internal thread scanning device and the drill pipe external thread scanning device are designed respectively for the female and male threads of the oil drill pipe; by replacing different external thread detection blocks and internal thread detection blocks, the thread teeth can be adapted to different drill pipes, and the overall device can also be adjusted accordingly, with strong versatility. Brief Description of the Drawings

[0044] Figure 1 It is a schematic structural diagram of the drill pipe external thread scanning device assembled on the drill pipe external thread in the present invention;

[0045] Figure 2 It is a schematic structural diagram of the drill pipe external thread scanning device in the present invention;

[0046] Figure 3 It is a schematic structural diagram of the drill pipe external thread scanning device removing the first skeleton ring in the present invention;

[0047] Figure 4 It is a schematic structural diagram of the external thread detection block in the present invention;

[0048] Figure 5 It is a schematic structural diagram of the drill pipe internal thread scanning device in the present invention;

[0049] Figure 6 It is a schematic structural diagram of the internal thread detection component in the present invention;

[0050] Figure 7 It is a schematic structural diagram of the internal thread detection block in the present invention;

[0051] Figure 8 It is a schematic structural diagram of the high-frequency eddy current probe in the present invention;

[0052] Figure 9 It is a schematic structural diagram of the detection system in the present invention;

[0053] Figure 10 It is a process control diagram of the detection system in the present invention.

[0054] Reference numerals:

[0055] 1. Drill pipe; 2. External thread scanning device for drill pipe; 21. First skeleton ring; 22. External thread detection component; 221. Detection block fixing frame; 222. External thread detection block; 223. First slider; 224. Circuit board cover; 225. Cable buckling cover; 23. External thread fixing component; 231. Lifting adjustment cylinder; 232. External thread support block; 233. First slide rail; 234. Adjusting rod; 24. Rubber band fixing port; 25. Rubber ring; 3. Internal thread scanning device for drill pipe; 31. Second skeleton ring; 32. Internal thread detection component; 321. Detection block fixing block; 322. Internal thread detection block; 323. Second slide rail; 33. Internal thread fixing component; 331. Adjusting frame; 332. Internal thread support block; 333. Second slider; 34. Spring; 4. High-frequency eddy current probe; 41. Ferrite; 42. Copper coil; 5. Eddy current detection circuit board; 6. Power supply; 7. Host computer. Detailed implementation manners

[0056] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The following describes the specific implementation manners of the present invention to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation manners. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0057] Embodiment 1

[0058] As Figures 1-9 shown, this embodiment provides a high-frequency eddy current-based thread detection device for oil drill pipes; the high-frequency eddy current-based thread detection device for oil drill pipes is used to comprehensively detect the thread defects of the external and internal threads of the drill pipe, and has high detection accuracy; it specifically includes:

[0059] External thread scanning device 2 for drill pipe, internal thread scanning device 3 for drill pipe, high-frequency eddy current probe 4 and detection system;

[0060] Among them, a plurality of high-frequency eddy current probes 4 are provided on both the drill pipe external thread scanning device 2 and the drill pipe internal thread scanning device 3, and the plurality of high-frequency eddy current probes 4 are respectively electrically connected to the detection system; the drill pipe external thread scanning device 2 is installed on the external thread of the drill pipe 1 for scanning the defects of the external thread of the drill pipe 1; the drill pipe internal thread scanning device 3 is installed on the internal thread of the drill pipe 1 for scanning the defects of the internal thread of the drill pipe 1.

[0061] The structure of the drill pipe external thread scanning device 2 is specifically as follows:

[0062] As Figure 2 shown, the drill pipe external thread scanning device 2 includes a first skeleton ring 21, an external thread detection component 22 and an external thread fixing component 23; the external thread detection component 22 and the external thread fixing component 23 are movably arranged on the first skeleton ring 21; the external thread detection component 22 and the external thread fixing component 23 are respectively clamped on both sides of the external thread of the drill pipe 1; a plurality of high-frequency eddy current probes 4 are provided on the external thread detection component 22. When scanning the defects of the external thread of the drill pipe 1, the external thread detection component 22 and the external thread fixing component 23 in the drill pipe external thread scanning device 2 are respectively clamped on both sides of the external thread of the drill pipe 1, and the high-frequency eddy current probes 4 on the external thread detection component 22 are used to comprehensively scan the defects of the external thread of the drill pipe 1.

[0063] As Figure 3 shown, the external thread detection component 22 includes a detection block fixing frame 221, an external thread detection block 222 and a first slider 223. The detection block fixing frame 221 is fixed on the inner side of the first skeleton ring 21; the external thread detection block 222 is installed on the detection block fixing frame 221. Threads are tapped on the side of the external thread detection block 222 close to the external thread of the drill pipe 1, and high-frequency eddy current probes 4 are installed on the threads of the external thread detection block 222, as Figure 4 shown.

[0064] As Figure 3 shown, the external thread fixing component 23 includes a lifting adjustment cylinder 231, an external thread support block 232, a first slide rail 233 and an adjustment rod 234; the lifting adjustment cylinder 231 is movably connected to the inner side of the first skeleton ring 21; the top of the external thread support block 232 is inserted into the lifting adjustment cylinder 231, and the bolt on the side wall of the lifting adjustment cylinder 231 fixes the external thread support block 232. The external thread support block 232 can be axially adjusted up and down relative to the lifting adjustment cylinder 231, and its position can be flexibly adjusted and fixed when installing the external thread support block 232; threads are tapped on the side of the external thread support block 232 close to the external thread of the drill pipe 1.

[0065] When detecting the external thread of the drill pipe 1, the sides with threads of the external thread detection block 222 and the external thread support block 232 are respectively connected to both sides of the external thread of the drill pipe 1. During the detection process, the first skeleton ring 21 is rotated, and the first skeleton ring 21 drives the two to move along the external thread of the drill pipe 1, thereby comprehensively scanning the external thread of the drill pipe 1.

[0066] One side of the detection block fixing frame 221 close to the lifting adjustment cylinder 231 is connected with a first slider 223, and one side of the lifting adjustment cylinder 231 close to the detection block fixing frame 221 is connected with a first slide rail 233. The first slider 223 is slidably connected to the first slide rail 233;

[0067] One side of the lifting adjustment cylinder 231 away from the detection block fixing frame 221 is connected with an adjustment rod 234. The adjustment rod 234 is movably arranged in the chute of the first skeleton ring 21 and is connected to the chute by bolts; Rubber band fixing ports 24 are provided on both the detection block fixing frame 221 and the external thread support block 232, and a rubber band is connected between the two rubber band fixing ports 24. Since the position of the external thread of the drill pipe 1 is conical, the distance between the external thread detection block 222 and the external thread support block 232 needs to be adjusted radially during each scanning process; during scanning, the external thread support block 232 moves radially under the pulling force of the rubber band, so that the external thread detection block 222 always fits with the external thread of the drill pipe 1; The design of the first slider 223 and the first slide rail 233 can ensure the accuracy and stability of the radial movement.

[0068] A circuit board accommodating groove is provided on the external thread detection block 222, and a circuit board cover 224 is installed on the circuit board accommodating groove by screws; A wire groove is provided on one side of the circuit board accommodating groove, and a cable fastening cover 225 is installed on the wire groove by screws. The circuit board accommodating groove in the external thread detection block 222 is used to accommodate the probe circuit board of the high-frequency eddy current probe 4 in the external thread detection block 222, and the circuit board cover 224 encapsulates the probe circuit board; The cable for connecting the probe circuit board passes through the wire groove, and the cable fastening cover 225 can fix the cable to prevent the connection position between the cable and the probe circuit board from being damaged due to pulling when the external thread detection block 222 is rotated.

[0069] The specific structure of the internal thread scanning device 3 of the drill pipe is as follows:

[0070] Such as Figure 5As shown, the internal thread scanning device 3 of the drill pipe includes a second skeleton ring 31, an internal thread detection component 32, and an internal thread fixing component 33; the internal thread detection component 32 and the internal thread fixing component 33 are movably arranged on the second skeleton ring 31; the internal thread detection component 32 and the internal thread fixing component 33 are respectively abutted against both sides of the internal thread of the drill pipe 1; a plurality of high-frequency eddy current probes 4 are arranged on the internal thread detection component 32; when scanning the defects of the internal thread of the drill pipe 1, the internal thread detection component 32 and the internal thread fixing component 33 are respectively supported on both sides of the internal thread of the drill pipe 1, and the high-frequency eddy current probes 4 on the internal thread detection component 32 perform a comprehensive scan on the internal thread of the drill pipe 1, with high scanning accuracy and fast speed.

[0071] The internal thread detection component 32 includes a detection block fixing block 321, an internal thread detection block 322, and a second slide rail 323; the detection block fixing block 321 is movably connected to the second skeleton ring 31; the internal thread detection block 322 is installed on the detection block fixing block 321, and the side of the internal thread detection block 322 close to the internal thread of the drill pipe 1 is tapped; high-frequency eddy current probes 4 are installed on the threads of the internal thread detection block 322, as Figure 7 shown.

[0072] The internal thread fixing component 33 includes an adjustment frame 331, an internal thread support block 332, and a second slider 333; the adjustment frame 331 is connected to the second skeleton ring 31; the bottom of the adjustment frame 331 is connected to the internal thread support block 332, and the side of the internal thread support block 332 close to the internal thread of the drill pipe 1 is tapped. The internal thread detection block 322 and the internal thread support block 332 are respectively supported on both sides of the internal thread of the drill pipe 1. During detection, rotating the second skeleton ring 31 drives the two to rotate, and the high-frequency eddy current probes 4 on the internal thread detection block 322 detect the internal thread of the drill pipe 1 during rotation.

[0073] A second slide rail 323 is connected to the side of the detection block fixing block 321 close to the adjustment frame 331, and a second slider 333 is connected to the side of the adjustment frame 331 close to the detection block fixing block 321; the second slider 333 is slidably connected to the second slide rail 323; a spring 34 is arranged between the detection block fixing block 321 and the internal thread support block 332; the spring 34 drives the detection block fixing block 321 to move radially along the direction of the second slide rail 323 through its elastic force, so that the internal thread detection block 322 is in contact with the internal thread of the drill pipe 1 to be measured.

[0074] The top of the second slider 333 is connected to the second skeleton ring 31 through a rod.

[0075] As Figure 6As shown, similar to the external thread detection block 222, a circuit board accommodation groove is also provided inside the internal thread detection block 322. A circuit board cover 224 is installed on the circuit board accommodation groove by screws; a wire routing groove is provided on one side of the circuit board accommodation groove, and a cable snap cover 225 is installed on the wire routing groove by screws. The circuit board accommodation groove inside the internal thread detection block 322 is used to accommodate the probe circuit board of the high-frequency eddy current probe 4 inside the internal thread detection block 322.

[0076] Rubber rings 25 are wrapped around both the first skeleton ring 21 and the second skeleton ring 31, and the rubber rings 25 play a role in protecting the hand.

[0077] The specific structure of the high-frequency eddy current probe 4 is as follows:

[0078] As Figure 8 shown, the high-frequency eddy current probe 4 includes two copper coils 42 and two ferrites 41. The two copper coils 42 are arranged side by side, and the two ferrites 41 are respectively fixed inside the two copper coils 42; the two copper coils 42 are connected to the detection system through a bridge-type adjustment circuit.

[0079] The two copper coils 42 are connected to a bridge-type conditioning circuit. When there is a defect at the bottom of one of the coils, the impedance of this coil changes, and the balance of the bridge is broken, so that the scanned defect can be responded and output. The high-frequency eddy current probe 4 composed of the copper coil 42 and the ferrite 41 has higher spatial resolution; the ferrite 41 has a high magnetic permeability, which can converge the magnetic induction lines generated by the copper coil 42 to enhance the magnetic field generated by the copper coil 42 and improve the eddy current detection sensitivity; the inductance of the copper coil 42 is between 0.1 - 50 uH, the resistance is between 0.1 - 10 Ω, the L∶R ratio is high, and the excitation signal frequency range is between 100 kHz - 3 MHz.

[0080] The specific structure of the detection system is as follows:

[0081] As Figure 9 shown, the detection system includes a probe circuit board, an eddy current detection circuit board 5, a host computer 7, and a power supply 6; the probe circuit board is connected to the copper coil 42 of the high-frequency eddy current probe 4 through a bridge-type adjustment circuit; the eddy current detection circuit board 5 is electrically connected to the probe circuit board, and the host computer 7 is electrically connected to the eddy current detection circuit board 5; the power supply 6 is connected to the eddy current detection circuit board 5 to supply power to the eddy current detection circuit board 5.

[0082] The probe circuit board is arranged in the circuit board accommodation groove of the external thread detection block 222 or the internal thread detection block 322 and is connected to the high-frequency eddy current probe 4 inside it, and can connect 16 high-frequency eddy current probes 4 simultaneously.

[0083] As Figure 10As shown in the figure, the eddy current detection circuit board 5 includes a pre-stage circuit, a system-on-chip (SOC) circuit, and an alarm unit that are connected in sequence; the pre-stage circuit is electrically connected to the probe circuit board, and the system-on-chip circuit is electrically connected to the host computer 7.

[0084] The pre-stage circuit includes a channel switching module, an excitation signal processing circuit, and an eddy current signal processing circuit. The channel switching module is electrically connected to the probe circuit board. The channel switching module can be switched to different channels according to the channel switching signal to control the high-frequency eddy current probes 4 at different positions for defect detection, and transmit the induction signal to the pre-stage circuit through a cable. The excitation signal processing circuit and the eddy current signal processing circuit are respectively used to process the excitation signal and the eddy current signal. The excitation signal is generated by a direct digital synthesis (DDS) module, amplified by the excitation signal processing circuit, and the DDS signal is converted into an analog signal through a DAC module. The reference voltage of the DAC module can be adjusted by a specific chip to adjust the amplitude of the output signal. The eddy current signal processing circuit is responsible for processing the differential eddy current signal after the bridge change, amplifying and performing analog-to-digital conversion, and sending it to the system-on-chip circuit.

[0085] The system-on-chip circuit includes a direct digital synthesis (DDS) module, a phase-sensitive demodulation module, a control unit, a serial port module, and an Ethernet communication module. The DDS module can generate digital signals with arbitrary frequencies and arbitrary waveforms such as sine waves, square waves, triangular waves, and sawtooth waves. The phase-sensitive demodulation module multiplies the voltage signal collected by the ADC module with the original output signal of the DDS module and the phase-shifted signal for phase-locked amplification to obtain the real part and the imaginary part of the induction signal, and finally analyzes and obtains the required impedance change signal.

[0086] The serial port module and the Ethernet communication module are responsible for the signal transmission between the host computer 7 and the system-on-chip circuit. The control unit is responsible for data parsing and data packaging for upward transmission, generating channel switching signals and controlling the alarm unit to alarm.

[0087] The host computer 7 is based on object-oriented language programming. It includes a UDP module, a serial port module, a database, an excitation signal control module, and a multi-channel signal display module. The excitation signal frequency, amplitude, gain, and channel information set by the host computer 7 are sent to the eddy current detection circuit board 5 by the UDP module and the serial communication module. The database module is used to save multi-channel signals for thread defect analysis. The excitation signal control module generates control signals such as excitation signal waveforms, frequencies, amplitudes, and gains. The multi-channel signal display module intuitively displays the real part and the imaginary part of the impedance in the form of a time-base diagram and an impedance diagram, facilitating the user to observe the scanning results in real time.

[0088] In this embodiment, a ZYNQ with the model number XC7Z020 is selected as the system-on-chip circuit.

[0089] In this embodiment, the alarm unit uses a buzzer or a warning light.

[0090] In this embodiment, the host computer 7 is preferably a computer.

[0091] Embodiment 2

[0092] Based on the oil drill pipe thread detection device based on high-frequency eddy current provided in Embodiment 1, this embodiment provides a method for detecting oil drill pipe threads based on high-frequency eddy current, which is used to detect the external thread defects of the drill pipe 1, and specifically includes the following steps:

[0093] Step 1: Connect the probe circuit board and the eddy current detection circuit board 5; connect the eddy current detection circuit board 5 to the host computer 7 through a network cable and a data cable, input the IP address and port number of the device in the host computer 7, set the COM port and baud rate, and open the corresponding serial port.

[0094] Step 2: Install the drill pipe external thread scanning device 2 on the drill pipe 1; the specific operation is as follows:

[0095] Place the external thread detection block 222 and the external thread support block 232 on both sides of the external thread of the drill pipe 1. First, fit the threaded side of the external thread detection block 222 to the external thread of the drill pipe 1; then loosen the bolt on the lifting adjustment cylinder 231 and make an axial fine adjustment to the external thread support block 232. After adjustment, fit the threaded side of the external thread support block 232 to the external thread of the drill pipe 1 and make their threads match.

[0096] Connect the rubber band fixing ports 24 on the detection block fixing frame 221 and the rubber band fixing ports 24 on the external thread support block 232 through a rubber band.

[0097] Drive the external thread detection block 222 and the external thread support block 232 to rotate through the first skeleton ring 21, so that the high-frequency eddy current probe 4 on the external thread detection block 222 is aligned with the thread position on the drill pipe without defects, and use this position as the initial position for detection.

[0098] Step 3: Set the alarm threshold of the alarm unit and the parameters of the high-frequency eddy current probe 4, such as waveform, frequency, gain, drive and other information in the host computer 7, and send this information to the system-on-chip circuit; click to set the balance center after the high-frequency eddy current probe 4 is aligned with the thread position on the drill pipe 1 without defects.

[0099] Step 4: Turn on the detection program, manually drive the rotation of the external thread scanning device 2 of the drill pipe, and start scanning. During the scanning process, the distance between the external thread detection block 222 and the external thread support block 232 adapts to the increase or contraction of the tapered structure of the external thread of the drill pipe 1. Under the tension of the rubber band, the external thread detection block 222 and the external thread support block 232 can always closely adhere to both sides of the external thread of the drill pipe 1;

[0100] When the high-frequency eddy current probe 4 detects a defect signal, the system-on-chip circuit controls the alarm unit to alarm.

[0101] Step 5: Repeat the scanning multiple times to verify the detection results and accurately determine the defect location.

[0102] Step 6: After the detection is completed, remove the rubber band; pull the external thread detection block 222 and the external thread support block 232 apart to both sides, remove them after they are separated from the external thread of the drill pipe 1, and avoid knocking against the external thread of the drill pipe 1 to damage the drill pipe 1; finally, export the detection data by the host computer 7 and perform scanning data processing, and the detection is over.

[0103] Embodiment 3

[0104] Based on the high-frequency eddy current-based oil drill pipe thread detection device provided in Embodiment 1, this embodiment provides a high-frequency eddy current-based oil drill pipe thread detection method for detecting internal thread defects of the drill pipe 1, which specifically includes the following steps:

[0105] Step 1: Connect the probe circuit board and the eddy current detection circuit board 5;

[0106] Step 2: Install the drill pipe internal thread scanning device 3 on the drill pipe 1; the specific operation is as follows:

[0107] Press the spring 34 between the internal thread detection block 322 and the internal thread support block 332, and extend the internal thread detection block 322 and the internal thread support block 332 into the drill pipe 1;

[0108] Make the threads of the internal thread detection block 322 and the internal thread support block 332 fit on both sides of the internal thread of the drill pipe 1;

[0109] Drive the rotation of the internal thread detection block 322 and the internal thread support block 332 through the second skeleton ring 31, so that the high-frequency eddy current probe 4 on the internal thread detection block 322 is aligned with the thread position on the drill pipe without defects, and use this position as the initial position for detection.

[0110] Step 3: Set the alarm threshold of the alarm unit and set the parameters of the high-frequency eddy current probe 4, such as waveform, frequency, gain, drive and other information in the host computer 7, and send this information to the system-on-chip circuit; click to set the balance center after the high-frequency eddy current probe 4 is aligned with the thread position on the drill pipe 1 without defects.

[0111] Step 4: Turn on the detection program, manually drive the rotation of the internal thread scanning device 3 of the drill pipe, and start scanning. During the scanning process, the distance between the internal thread detection block 322 and the internal thread support block 332 adapts to the increase or contraction of the tapered structure of the internal thread of the drill pipe 1. Supported by the spring 34, the internal thread detection block 322 and the internal thread support block 332 can always be in close contact with the inner wall of the internal thread of the drill pipe 1;

[0112] When the high-frequency eddy current probe 4 detects a defect signal, the system-on-chip circuit controls the alarm unit to give an alarm.

[0113] Step 5: Repeat the scanning multiple times to verify the detection result and accurately determine the defect location.

[0114] Step 6: After the detection is completed, squeeze the spring 34 by the internal thread detection block 322 and the internal thread support block 332 towards the middle. After the threads of the internal thread detection block 322 and the internal thread support block 332 are completely disengaged from the internal thread of the drill pipe 1, then take out the internal thread scanning device 3 of the drill pipe; finally, the upper computer 7 exports the detection data and processes the scanning data.

[0115] Those of ordinary skill in the art will realize that the embodiments here are to help readers understand the principles of the present invention. It should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations that do not depart from the essence of the present invention according to these technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the invention.

Claims

1. An oil drill pipe thread detection device based on high-frequency eddy current, characterized in that: It includes an external drill pipe thread scanning device (2) and an internal drill pipe thread scanning device (3); a number of high-frequency eddy current probes (4) are provided on both the external drill pipe thread scanning device (2) and the internal drill pipe thread scanning device (3), and the number of the high-frequency eddy current probes (4) are electrically connected to the detection system respectively; the external drill pipe thread scanning device (2) is installed on the external thread of the drill pipe (1) for scanning the defects of the external thread of the drill pipe (1); the internal drill pipe thread scanning device (3) is installed on the internal thread of the drill pipe (1) for scanning the defects of the internal thread of the drill pipe (1). The external drill pipe thread scanning device (2) includes a first skeleton ring (21), and an external thread detection component (22) and an external thread fixing component (23) are movably arranged on the first skeleton ring (21); the external thread detection component (22) and the external thread fixing component (23) are respectively clamped on both sides of the external thread of the drill pipe (1). The internal drill pipe thread scanning device (3) includes a second skeleton ring (31), and an internal thread detection component (32) and an internal thread fixing component (33) are movably arranged on the second skeleton ring (31); the internal thread detection component (32) and the internal thread fixing component (33) are respectively abutted against both sides of the internal thread of the drill pipe (1); the high-frequency eddy current probe (4) is arranged on the external thread detection component (22) and the internal thread detection component (32). The external thread detection component (22) includes a detection block fixing frame (221), and the detection block fixing frame (221) is fixed on the inner side of the first skeleton ring (21); an external thread detection block (222) is installed on the detection block fixing frame (221), threads are tapped on the side of the external thread detection block (222) close to the external thread of the drill pipe (1), and the high-frequency eddy current probe (4) is installed on the thread teeth of the external thread detection block (222). The external thread fixing component (23) includes a lifting adjustment cylinder (231) and an external thread support block (232), and the lifting adjustment cylinder (231) is movably connected to the inner side of the first skeleton ring (21); the top of the external thread support block (232) is arranged inside the lifting adjustment cylinder (231), and the external thread support block (232) is fixed by a bolt on the side wall of the lifting adjustment cylinder (231); threads are tapped on the side of the external thread support block (232) close to the external thread of the drill pipe (1); the external thread support block (232) can be axially adjusted up and down relative to the lifting adjustment cylinder (231), and its position can be flexibly adjusted and fixed when installing the external thread support block (232). One side of the detection block fixing bracket (221) close to the lifting adjustment cylinder (231) is connected with a first slider (223), and one side of the lifting adjustment cylinder (231) close to the detection block fixing bracket (221) is connected with a first slide rail (233). The first slider (223) is slidably connected to the first slide rail (233); One side of the lifting adjustment cylinder (231) away from the detection block fixing bracket (221) is connected with an adjustment rod (234). The adjustment rod (234) is movably arranged in the chute of the first skeleton ring (21) and is connected to the chute by bolts; Rubber band fixing ports (24) are arranged on both the detection block fixing bracket (221) and the external thread support block (232), and a rubber band is connected between the two rubber band fixing ports (24); Since the position of the external thread of the drill pipe (1) is conical, the distance between the external thread detection block (222) and the external thread support block (232) needs to be adjusted radially during each scanning process; During scanning, the external thread support block (232) moves radially under the action of the tension of the rubber band, so that the external thread detection block (222) always fits with the external thread of the drill pipe (1); Designing the first slider (223) and the first slide rail (233) can ensure the accuracy and stability of the radial movement; The internal thread detection assembly (32) includes a detection block fixing block (321), and the detection block fixing block (321) is movably connected to the second skeleton ring (31); An internal thread detection block (322) is installed on the detection block fixing block (321), and threads are tapped on one side of the internal thread detection block (322) close to the internal thread of the drill pipe (1); The high-frequency eddy current probe (4) is installed on the thread teeth of the internal thread detection block (322); The internal thread fixing assembly (33) includes an adjustment frame (331), and the adjustment frame (331) is connected to the second skeleton ring (31); The bottom of the adjustment frame (331) is connected with an internal thread support block (332), and threads are tapped on one side of the internal thread support block (332) close to the internal thread of the drill pipe (1); One side of the detection block fixing block (321) close to the adjustment frame (331) is connected with a second slide rail (323), and one side of the adjustment frame (331) close to the detection block fixing block (321) is connected with a second slider (333); The second slider (333) is slidably connected to the second slide rail (323); A spring (34) is arranged between the detection block fixing block (321) and the internal thread support block (332); The top of the second slider (333) is connected to the second skeleton ring (31) through a rod.

2. The oil drill pipe thread detection device based on high-frequency eddy current according to claim 1, wherein: A circuit board accommodating groove is formed on the external thread detection block (222), and a circuit board cover (224) is installed on the circuit board accommodating groove by screws; A wire routing groove is formed on one side of the circuit board accommodating groove, and a cable fastening cover (225) is installed on the wire routing groove by screws.

3. The oil drill pipe thread detection device based on high-frequency eddy current according to claim 1, characterized in that: The high-frequency eddy current probe (4) includes two copper coils (42) arranged side by side, and two ferrite cores (41) are respectively fixed inside the two copper coils (42); the two copper coils (42) are connected to the detection system through a bridge-type adjustment circuit.

4. The oil drill pipe thread detection device based on high-frequency eddy current according to claim 3, characterized in that: The detection system includes a probe circuit board, an eddy current detection circuit board (5), and a host computer (7). The probe circuit board is connected to the copper coil (42) of the high-frequency eddy current probe (4) through a bridge-type adjustment circuit; the eddy current detection circuit board (5) is electrically connected to the probe circuit board, and the host computer (7) is electrically connected to the eddy current detection circuit board (5); The eddy current detection circuit board (5) includes a preamplifier circuit, a system-on-chip circuit, and an alarm unit connected in sequence; the preamplifier circuit is electrically connected to the probe circuit board, and the system-on-chip circuit is electrically connected to the host computer (7).

5. A detection method for the detection device of oil drill pipe threads based on high-frequency eddy current according to any one of claims 1 to 4, characterized in that, It includes the following steps: Step 1: Connect the probe circuit board and the eddy current detection circuit board (5); Step 2: Install a drill pipe external thread scanning device (2) or a drill pipe internal thread scanning device (3) on the drill pipe (1); Step 3: Set the alarm threshold of the alarm unit and the parameters of the high-frequency eddy current probe (4) in the host computer (7); after aligning the high-frequency eddy current probe (4) with the defect-free thread position on the drill pipe (1), click to set the balance center; Step 4: Start the detection program, rotate the drill pipe external thread scanning device (2) or the drill pipe internal thread scanning device (3) to start scanning. When the high-frequency eddy current probe (4) detects a defect signal, the system-on-chip circuit controls the alarm unit to alarm; Step 5: After the scanning is completed, remove the drill pipe external thread scanning device (2) or the drill pipe internal thread scanning device (3), export the detection data by the host computer (7) and perform scanning data processing, and the detection ends.

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