Drill rod machining method and machining device

Abstract

The embodiment of the invention relates to the technical field of machine manufacturing, and discloses a drill rod machining method and device. A specific implementation mode of the method comprises the following steps: forging two ends of a cold-drawn steel pipe to obtain a forged pipe; the forged pipe is annealed at the temperature of 650-720 DEG C, heat preservation is conducted for 2.5-3.5 hours, and an annealed pipe is obtained; the annealed pipe is straightened in multiple directions, and a straightened pipe with the straightness per meter smaller than or equal to 0.5 mm is obtained; the straightened pipe is subjected to local quenching, the pipe subjected to local quenching is obtained, the surface hardness of a quenching area is 23-28 HRC, and the thickness of a hardened layer is 6.5 + / -0.3 mm; male threads and female threads are machined at the two ends of the pipe after local quenching, the surface hardness ranges from 47 HRC to 55 HRC, the surface hardness ranges from 30 HRC to 38 HRC, the depth of a hardened layer ranges from 1.5 + / -0.1 mm, the depth of a hardened layer is not smaller than 2 mm, the pipe with the threads is obtained and verified, and the pipe passing verification is determined to be a drill rod finished product. According to the implementation mode, the threads are directly machined at the two ends of the drill rod, the connecting strength of the rod body and the threaded end of the drill rod is improved, and the technical problem that the connecting strength of the rod body and the threaded end is poor is solved.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the field of mechanical manufacturing technology, and more particularly to a drill rod processing method and a processing device. Background Art

[0002] Drill pipe is a key component that connects the drilling rig and drill bit, and transmits power and mud during drilling operations. Currently, friction welding is commonly used to connect the drill pipe body and threaded end.

[0003] However, when the drill rod is processed in the above-mentioned manner, there is often a technical problem that the strength of the connection between the rod body and the threaded end is poor.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure concept and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the Invention

[0005] The content of this disclosure is used to briefly introduce concepts that will be described in detail in the detailed description section below. The content of this disclosure is not intended to identify key features or essential features of the claimed technical solution, nor is it intended to limit the scope of the claimed technical solution.

[0006] Some embodiments of the present disclosure provide a drill rod processing method and a drill rod processing device to solve one or more of the technical problems mentioned in the above background technology section.

[0007] In a first aspect, some embodiments of the present disclosure provide a drill pipe processing method, which includes using a cold-drawn steel pipe as a base material, processing both ends of the cold-drawn steel pipe by a forging process to obtain a forged pipe; placing the forged pipe in an annealing furnace for annealing to obtain an annealed pipe, wherein the annealing temperature is 650~720℃ and the holding time is 2.5~3.5 hours; using a hydraulic straightening machine to perform multi-directional straightening on the annealed pipe to obtain a straightened pipe, wherein the straightness of the straightened pipe per meter is less than or equal to 0.5mm; using induction quenching equipment to perform local hardening on the straightened pipe. The locally quenched pipe is subjected to partial quenching treatment to obtain a locally quenched pipe, wherein the surface hardness of the quenched area of the locally quenched pipe is between 23 and 28 HRC, and the thickness of the hardened layer is 6.5±0.3 mm; a CNC lathe is used to respectively machine male and female threads at both ends of the locally quenched pipe to obtain a threaded pipe, wherein the surface hardness of the male thread is between 47 and 55 HRC, and the depth of the hardened layer is 1.5±0.1 mm, and the surface hardness of the female thread is between 30 and 38 HRC, and the depth of the hardened layer is greater than or equal to 2 mm; the threaded pipe is verified; and the threaded pipe that passes the verification is determined as a finished drill pipe.

[0008] Optionally, the cold-drawn steel pipe is used as the base material, and both ends of the cold-drawn steel pipe are processed by a forging process to obtain a forged pipe, including: using a forging die to upset the two ends of the cold-drawn steel pipe to obtain the forged pipe, wherein the outer diameters of both ends of the forged pipe reach 110% to 120% of the target size, and the inner diameter is reduced to 85% to 90% of the target size.

[0009] Optionally, the forged tube is placed in an annealing furnace for annealing to obtain the annealed tube, comprising: providing a tube support inside the annealing furnace; placing the forged tube on the tube support, wherein the spacing between adjacent forged tubes is 80-120 mm; introducing a protective gas into the annealing furnace; heating the annealing furnace to 650-720° C. at a rate of less than or equal to 45° C. / hour; controlling the holding time to be 2.5-3.5 hours to obtain a pre-annealed tube; furnace cooling the pre-annealed tube to 450° C. to obtain a pre-cooled tube; and air cooling the pre-cooled tube to room temperature to obtain the annealed tube.

[0010] Optionally, the hydraulic straightening machine is used to perform multi-directional straightening on the annealed pipe to obtain the straightened pipe, comprising: selecting a suitable fixture according to the diameter of the annealed pipe; Install the selected fixture on the hydraulic straightening machine; install the annealed pipe into the hydraulic straightening machine; inspect the annealed pipe after being processed by the hydraulic straightening machine; and determine the annealed pipe that passes the inspection as the straightened pipe.

[0011] Optionally, the above-mentioned use of a CNC lathe to respectively process male and female threads at both ends of the partially quenched pipe to obtain a threaded pipe includes: controlling the CNC lathe to turn one end of the partially quenched pipe to obtain a male thread; boring the other end of the partially quenched pipe to obtain a female thread processing area; thread milling the female thread processing area to obtain a female thread; and quenching the obtained male and female threads to obtain the threaded pipe.

[0012] Optionally, the checking of the threaded pipe includes: using flaw detection equipment to detect the male thread and the female thread.

[0013] Optionally, the rod body of the drill rod finished product is surface cleaned to obtain a cleaned drill rod; a wear-resistant coating is added to the rod body of the cleaned drill rod to obtain a reinforced drill rod, wherein the thickness of the wear-resistant coating is 0.8-1.2 mm.

[0014] Optionally, before the above-mentioned induction quenching equipment is used to perform local quenching treatment on the above-mentioned straightened pipe to obtain the locally quenched pipe, the above-mentioned method also includes: installing an exciter on the above-mentioned straightened pipe; controlling the above-mentioned exciter to vibrate at a preset frequency and a preset time to obtain a vibrated pipe, wherein the above-mentioned preset time is greater than or equal to 40 minutes, and the above-mentioned preset frequency is 80~90% of the natural frequency of the above-mentioned straightened pipe.

[0015] Optionally, the induction quenching equipment is used to perform local quenching treatment on the straightened pipe to obtain the locally quenched pipe, including: controlling the induction quenching equipment to use 1.2~1.8kHz alternating current to preheat the target quenching area of the straightened pipe to 550~600℃ to obtain the preheated pipe; keeping the preheated pipe warm for 30~45 seconds to obtain the insulated pipe; controlling the induction quenching equipment to use 25~35kHz alternating current to quench the target quenching area of the insulated pipe The regional temperature is raised to 880-920°C to obtain a completely heated pipe; the sprayer is controlled to spray a coolant at 20-25°C at a spray pressure of 0.25-0.35 MPa to obtain a cooled pipe, wherein the spray angle of the above-mentioned sprayer is 30-45° with the axis of the above-mentioned completely heated pipe, and the continuous spraying time is 8.5-10.5 seconds; an auxiliary heater is arranged 50 mm outside the quenching area, and tempering is performed at 200-250°C to obtain a partially quenched pipe.

[0016] In the second aspect, some embodiments of the present disclosure provide a drill rod processing device, which includes an annealing furnace, a CNC lathe, a hydraulic straightening machine and an induction quenching equipment, wherein the above-mentioned induction quenching equipment includes a sprayer and an auxiliary heater; the above-mentioned drill rod processing device is configured to execute the method described in any implementation method of the above-mentioned first aspect.

[0017] Some embodiments of the present disclosure provide a drill rod processing method that can improve the connection strength between the rod body and the threaded end of the drill rod. Specifically, the reason why the connection strength between the rod body and the threaded end of most drill rods is low is that friction welding is commonly used to connect the rod body and the threaded end of the drill rod, and friction welding may produce welding defects such as pores and cracks. Based on this, some embodiments of the present disclosure provide a drill rod processing method, which includes using a cold-drawn steel pipe as a base material, and processing the two ends of the above-mentioned cold-drawn steel pipe by a forging process to obtain a forged pipe; placing the above-mentioned forged pipe in an annealing furnace for annealing treatment to obtain an annealed pipe, wherein the annealing temperature is 650~720℃, and the holding time is 2.5~3.5 hours; using a hydraulic straightening machine to perform multi-directional straightening on the above-mentioned annealed pipe to obtain a straightened pipe, wherein the straightness of the above-mentioned straightened pipe per meter is less than or equal to 0.5mm; using induction quenching equipment to perform local hardening on the above-mentioned straightened pipe The drill pipe is partially quenched to obtain a partially quenched pipe, wherein the surface hardness of the quenched area of the partially quenched pipe is between 23 and 28 HRC, and the thickness of the hardened layer is 6.5 ± 0.3 mm. A CNC lathe is used to machine male and female threads at both ends of the partially quenched pipe to obtain a threaded pipe, wherein the surface hardness of the male thread is between 47 and 55 HRC, the depth of the hardened layer is 1.5 ± 0.1 mm, and the surface hardness of the female thread is between 30 and 38 HRC, and the depth of the hardened layer is greater than or equal to 2 mm. The threaded pipe is then inspected, and the threaded pipe that passes the inspection is determined to be a finished drill pipe. By using cold-drawn steel pipe to produce threads through forging and milling, the process of welding the threaded end to the rod body is avoided, and the entire drill pipe is made of a single, complete steel pipe. This improves the connection strength between the rod body and the threaded end of the drill pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other features, advantages, and aspects of the various embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and that components and elements are not necessarily drawn to scale.

[0019] Figure 1 is a flow chart of some embodiments of a drill rod processing method according to the present disclosure; Figure 2 is a schematic structural diagram of a drill rod obtained by processing according to some embodiments of the drill rod processing method disclosed herein; Figure 3 1 is a cross-sectional view of a drill rod obtained by processing according to some embodiments of the drill rod processing method disclosed herein. DETAILED DESCRIPTION

[0020] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein. On the contrary, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0021] It should also be noted that, for ease of description, only the parts related to the invention are shown in the drawings. In the absence of conflict, the embodiments and features in the embodiments of the present disclosure may be combined with each other.

[0022] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0023] It should be noted that the modifications of "one" and "multiple" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0024] The names of the messages or information exchanged between multiple devices in the embodiments of the present disclosure are only used for illustrative purposes and are not used to limit the scope of these messages or information.

[0025] The present disclosure will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0026] Figure 1 A process 100 of some embodiments of the drill rod processing method of the present disclosure is shown. The drill rod processing method includes the following steps: Step 101: Processing both ends of the cold-drawn steel pipe by a forging process to obtain a forged pipe.

[0027] In some embodiments, the cold-drawn steel pipe is used because it has a dense internal structure and is free of defects such as pores, reducing the risk of fracture during drilling operations. The forging process may include an upsetting process. A forging die can be used to upset both ends of the cold-drawn steel pipe to produce the forged pipe. Forging enhances the mechanical properties of the pipe ends, providing a high-strength foundation for subsequent threading. The outer diameters of both ends of the forged pipe can be machined to 110%-120% of the target dimensions, while the inner diameter can be reduced to 85%-90% of the target dimensions to allow for subsequent machining. The target dimensions may refer to the desired outer and inner diameters of the finished drill pipe. In practice, a cold-drawn steel pipe of the designed length (e.g., 4 meters) can be directly axially upset at room temperature. This forging method may result in nonlinear springback after unloading, resulting in the pipe failing to reach the target dimensions.

[0028] In some optional implementations of some embodiments, the forged pipe may be obtained by the following steps: The first step is to cut the cold-drawn steel pipe to the designed length (e.g., 4 meters). Note that due to the subsequent upsetting process, the pipe length may be shortened, so the designed pipe length can be slightly longer than the desired drill pipe. This length can be adjusted based on the diameter and wall thickness of the cold-drawn steel pipe and the desired drill pipe specifications, and is not specifically limited here.

[0029] The second step is to remove the oxide scale of the cold-drawn steel pipe of the above-designed length by sandblasting or pickling to reduce impurity contamination during forging.

[0030] The third step is to preheat the mold to 300-350°C. This can reduce the temperature difference between the mold and the high-temperature steel pipe, slow down the cooling rate of the steel pipe when it contacts the mold, significantly reduce thermal stress, and thus reduce the possibility of rapid cooling cracking.

[0031] In the fourth step, a high-frequency induction coil is then used to heat both ends of the steel pipe of the above-designed length to 1100~1150℃ (which can be adjusted according to the material of the steel pipe) so that the steel pipe reaches the austenitized state and obtains a heated pipe.

[0032] In the fifth step, a hydraulic press is used to axially push one end of the heated pipe until the outer diameter of the end reaches 110% to 120% of the target size and the inner diameter is reduced to 85% to 90% of the target size. Then, the other end is axially pushed to obtain the upset pipe.

[0033] In the sixth step, the upset pipe is cooled to obtain a forged pipe.

[0034] Step 102: placing the forged pipe into an annealing furnace for annealing to obtain an annealed pipe.

[0035] In some embodiments, the annealing treatment can eliminate residual stress in the forged pipe, improving the material's machinability and microstructure uniformity. In practice, the forged pipe can be placed in an annealing furnace (e.g., a pit annealing furnace), heated to 650-720°C at a rate of 40-60°C / hour, held at that temperature for 2.5-3.5 hours, and then cooled to room temperature in the annealing furnace to obtain the annealed pipe.

[0036] In some optional implementations of some embodiments, the forged pipe may be annealed by the following steps: The first step is to install a pipe support inside an annealing furnace (such as a box-type annealing furnace). The pipe support must be made of a high-temperature, oxidation-resistant material (such as 310S stainless steel). A high-temperature ceramic coating can be applied to the surface of the pipe support to reduce the metal's oxidation rate. The pipe support can be multi-layered to facilitate processing of multiple pipes at once, improving processing efficiency.

[0037] The second step is to place the forged pipes on a pipe support. The spacing between adjacent forged pipes can be 80-120 mm (depending on the pipe diameter). This spacing between adjacent forged pipes can help prevent heat radiation from being blocked by adjacent pipes, ensuring even heating.

[0038] The third step is to introduce a shielding gas into the annealing furnace. This shielding gas can be an inert gas (such as nitrogen or argon). This shielding gas can improve the surface quality of the forged pipe. For example, under pure nitrogen, the oxide layer thickness of carbon steel can be reduced to less than 0.5 μm.

[0039] In the fourth step, the PID temperature control system is used to raise the temperature in the annealing furnace to 650-720°C at a rate of 45°C / hour or less. Because lattice distortion and residual stress exist within the tube after forging, rapid temperature increases (e.g., >50°C / hour) can generate additional thermal stress due to the internal and external temperature differential. The combined effect of these stresses can easily exceed the material's yield strength, leading to cracking. Therefore, a slow temperature increase of 45°C / hour or less allows for sufficient diffusion of metal atoms and gradually eliminates the residual stresses generated by forging. 650°C is higher than the recrystallization temperature of carbon steel (approximately 600°C), ensuring that work hardening is eliminated to a certain extent. 720°C can, to a certain extent, prevent excessive temperatures from causing grain coarsening and reduced strength, while also reducing scale formation.

[0040] The fifth step is to control the holding time to 2.5 to 3.5 hours to obtain a pre-annealed pipe.

[0041] In the sixth step, the pre-annealed tube is cooled to 450°C in an annealing furnace to obtain pre-cooled tube. The tube surface temperature can be monitored in real time using an infrared thermal imager. The slow cooling rate in the annealing furnace can reduce thermal stress to a certain extent and prevent deformation or cracking.

[0042] In the seventh step, when it is detected that the surface temperature of the pre-annealed pipe has dropped to 450° C., the pre-cooled pipe is transferred out of the annealing furnace and cooled to room temperature in air to obtain an annealed pipe.

[0043] In some optional implementations of some embodiments, the annealed tube may be obtained by the following steps: The first step is to use nitrogen to perform a preset number of displacement purges on the annealing furnace to create an inert environment. Each displacement purge can last for 5 to 8 minutes. The preset number of times can be 3, and there is no specific limit here, as long as an inert environment with an oxygen content of 200ppm can be created inside the above-mentioned furnace. Before placing the pipes, the interior of the above-mentioned furnace is empty and the gas flow effect is better. At this time, displacement purge can improve the efficiency of displacement and make the oxygen content reach the target level more quickly.

[0044] The second step is to place the forged tube in an inert environment along a predetermined direction within the furnace. This predetermined direction aligns with the direction of airflow within the furnace. This allows for smooth gas flow within the furnace, enhancing the annealing process and effectively eliminating stress within the tube.

[0045] The third step is to introduce nitrogen into the furnace. The nitrogen flow rate can be controlled at 15-25 m³ / h, and the gas pressure inside the furnace can be maintained at 50-150 Pa.

[0046] The fourth step is to heat the forged pipe to 350°C at a heating rate of 25°C / hour or less to obtain a first-stage heated pipe. Heating at a heating rate of 25°C / hour or less can reduce deformation of the forged pipe caused by sudden heating.

[0047] The fifth step is to heat the first-stage heated pipe to 550°C at a heating rate of 15°C / hour or less to obtain the second-stage heated pipe. The temperature range of 350°C to 550°C is generally the blue-brittle sensitive zone of steel, where steel toughness decreases. Therefore, the heating rate can be further reduced to improve the structural stability of the pipe during heating.

[0048] The sixth step is to heat the secondary heating pipe to 650-720°C at a heating rate of 35°C / hour or less to obtain the tertiary heating pipe. After reaching the blue-brittle sensitive temperature range, the pipe's structural properties are relatively stable, and the heating rate can be increased appropriately to accelerate the heating process.

[0049] In the seventh step, the three-stage heated pipe is subjected to insulation treatment to obtain the insulated pipe. The nitrogen flow rate within the furnace can be controlled at 8-12 m³ / h. The gas pressure within the furnace can be maintained at 30-80 Pa, the wind speed of the circulating fan can be controlled at 1.5-2.5 m / s, and the insulation time can be 2.5-3.5 hours. This ensures that the carbides are fully spheroidized (e.g., a spheroidization rate greater than or equal to 90%) to eliminate forging stress.

[0050] In the eighth step, the pipe is cooled to 450°C at a controlled rate of 30°C / hour or less, with a nitrogen flow rate of 15-25 m³ / h, to obtain a first-stage cooled pipe. This allows the pipe to fully complete the pearlite transformation to a certain extent, thereby reducing the possibility of residual stress regeneration.

[0051] Step 9: Transfer the primary cooling pipe to a forced air cooling area and cool it to room temperature, thereby obtaining a secondary cooling pipe. The wind speed in the forced air cooling area can be 8 m / s or higher. This forced air cooling area can include an area equipped with an axial flow fan. In practice, a bridge crane can be used to transfer the primary cooling pipe to the forced air cooling area. The axial flow fan is activated at a wind speed of 8 m / s or higher to provide forced convection cooling of the primary cooling pipe.

[0052] Step 10: Perform metallographic analysis on the secondary cooling tube to obtain metallographic analysis results. In practice, samples can be taken from both ends and the middle of the secondary cooling tube for metallographic analysis. The metallographic analysis results can include information on the grain size and banded structure of the sample.

[0053] In step 11, in response to the metallographic analysis results being qualified, the secondary cooling pipe is determined to be an annealed pipe. In practice, a metallographic analysis result with a grain size ≥ 7 and a banded structure ≤ 2 can be determined as qualified, and the corresponding secondary cooling pipe is determined to be an annealed pipe.

[0054] The above-mentioned first to eleventh steps, as an inventive point of an embodiment of the present disclosure, solve the technical problem of "poor toughness of drill pipes". The factors that lead to poor toughness of drill pipes are as follows: In the current annealing treatment of drill pipes, a fixed heating rate is usually used to heat the pipe to the target temperature, ignoring the blue brittle phenomenon of the pipe. If the above factors are solved, the effect of improving the wear resistance of the drill pipe thread can be achieved. In order to achieve this effect, the present disclosure also provides an annealing method. By reducing the heating rate in the blue brittle zone of the pipe, carbon atoms are fully diffused to the grain boundaries, reducing the enrichment and pinning at the dislocation line, thereby releasing the plastic deformation ability of the dislocation slip. Thereby, the toughness of the drill pipe is improved.

[0055] Step 103: Use a hydraulic straightening machine to perform multi-directional straightening on the annealed pipe to obtain a straightened pipe.

[0056] In some embodiments, a hydraulic straightening machine can be used to perform multi-directional straightening on the annealed tubing to produce a straightened tubing. The hydraulic straightening machine is a specialized device that utilizes hydraulic transmission principles to straighten bent or deformed workpieces (such as shafts, tubes, and plates), restoring the workpiece to its straightness by applying controllable pressure.

[0057] In some optional implementations of some embodiments, the annealed tube may be straightened by the following steps: The first step is to select the appropriate clamp based on the diameter of the annealed tube. For example, based on the outer diameter of the annealed tube, choose a clamp (such as a V-block) with an inner diameter 0.1-0.3mm larger than the outer diameter of the tube. This reduces the possibility of deformation due to overtightening or slippage due to overloosening. Nylon or copper clamps are also preferred to minimize indentation.

[0058] The second step is to install the selected fixture on the hydraulic straightening machine, for example, by fixing the base of the fixture to the hydraulic straightening machine with bolts.

[0059] The third step is to install the annealed pipe into the hydraulic straightening machine. For example, place the annealed pipe in the center of the clamp. For pipes longer than 3 meters, at least one support frame can be installed in the middle to prevent the pipe from sagging under its own weight.

[0060] The fourth step is to visually inspect the annealed tubing after the hydraulic straightening process. For example, observe the tubing under strong light for indentations, scratches, or flaking oxide scale. Wearing white gloves, wipe the tubing to check for burrs or unevenness. Alternatively, use a dial indicator to measure straightness.

[0061] In the fifth step, the annealed pipes that have passed the inspection are identified as straightened pipes. For example, pipes with no surface indentations, scratches, oxide scale peeling, burrs, or unevenness, and a straightness of less than or equal to 0.5 mm per meter, can be identified as straightened pipes.

[0062] Alternatively, because the straightening process may generate residual stress within the pipe, direct quenching may result in deformation due to stress concentration during quenching. Therefore, before performing partial quenching on the straightened pipe, the following steps can be performed to release the residual stress generated by straightening: The first step is to install a vibrator on the straightened pipe. This vibrator can be an electromagnetic vibrator. In practice, there are at least two possible installation scenarios: if the straightened pipe is uniform and symmetrical, the vibrator can be installed in the center (the stress concentration area); if there is a straightening indentation, the vibrator can be installed at the location corresponding to the indentation (directly acting on the high stress area).

[0063] The second step is to control the vibrator to vibrate at a preset frequency and for a preset duration to obtain the vibrated pipe. The preset frequency can be 80-90% of the natural frequency of the straightened pipe. The preset duration can be 40 minutes or longer. This maximizes the release of residual stress while minimizing material damage.

[0064] Step 104 : Using induction hardening equipment to perform local quenching treatment on the straightened pipe to obtain a locally quenched pipe.

[0065] In some embodiments, the induction hardening equipment can be a device that generates an alternating magnetic field by passing high-frequency alternating current through a coil, causing eddy current heating of the workpiece surface. The localized hardening treatment can be performed on the straightened tube, excluding the area where threads will be subsequently processed. In practice, the induction hardening equipment can be driven by high-frequency alternating current to heat the target quenching area of the straightened tube to 880-920°C, followed by immersion of the entire tube in a quenching liquid (e.g., pure water) to cool it.

[0066] In some optional implementations of some embodiments, the quenched pipe may be obtained by the following steps: The first step is to control the induction hardening equipment to preheat the target quenching area of the straightened pipe to 550-600°C using 1.2-1.8kHz AC current, resulting in a preheated pipe. The 1.2-1.8kHz AC current has a greater penetration depth, allowing for uniform heating within the target quenching area. This can, to a certain extent, reduce deformation or cracking caused by rapid temperature increases and more easily achieve the goal of controlling the hardened layer thickness to 6.5±0.3mm. Furthermore, an infrared thermometer can be used to monitor whether the temperature of the target quenching area has risen to 550-600°C.

[0067] The second step is to hold the preheated tubing at this temperature for 30-45 seconds to obtain an insulated tubing. This 30-45-second hold ensures a uniform temperature distribution within the target quenching area, eliminating temperature gradients to a certain extent. This can also reduce grain coarsening and uneven performance caused by localized overheating during subsequent high-temperature heating.

[0068] In the third step, the induction hardening equipment uses 25-35kHz AC current to raise the target quenching area of the insulated pipe to 880-920°C, achieving complete heating of the pipe. The 25-35kHz high-frequency current rapidly raises the surface temperature of the target quenching area to 880-920°C. This rapid heating increases the hardness of the pipe after quenching, achieving a controlled surface hardness of 23-28HRC.

[0069] The fourth step is to control the sprayer to spray quenching liquid at 20~25℃ at a spray pressure of 0.25~0.35MPa to obtain the cooled pipe. Among them, the multiple nozzles of the sprayer can be arranged in an array around the above-mentioned fully heated pipe. The spray angle can be pre-adjusted to an angle of 30~45° with the axis of the fully heated pipe, and the continuous spray time can be controlled by the PLC program to be 8.5~10.5 seconds. The 30~45° angle can reduce the occurrence of liquid flow rebound to a certain extent. The spray pressure of 0.25~0.35MPa can prevent the deformation of the above-mentioned fully heated pipe due to excessive impact to a certain extent. In addition, the flow meter and pressure sensor can be used to ensure parameter stability to a certain extent.

[0070] In the fifth step, an auxiliary heater is placed 50 mm outside the quenching area to temper the pipe at 200-250°C to obtain a partially quenched pipe. This setting can eliminate quenching stress to a certain extent and improve material toughness.

[0071] Step 105 , using a CNC lathe to process male and female threads on both ends of the partially quenched pipe to obtain a threaded pipe.

[0072] In some embodiments, male and female threads are directly machined on both ends of the partially quenched pipe, using a single base material rather than machining the threaded end and the rod separately and then welding them together. This can enhance the mechanical properties of the rod and threaded end. In practice, the threaded pipe can be obtained by the following steps: The first step is to control the CNC lathe to turn one end of the partially quenched pipe to obtain a male thread.

[0073] The second step is to bore the other end of the partially quenched tube to create the female thread processing area. This is done because quenching can cause slight deformation of the tube's inner bore profile, and boring can correct this inner diameter error to some extent. Furthermore, the bored hole diameter can be slightly smaller than the female thread minor diameter to allow for thread milling.

[0074] The third step is to perform thread milling on the female thread processing area to obtain the female thread.

[0075] The fourth step is to quench the resulting male and female threads to produce threaded pipe. Quenching is intended to achieve a surface hardness of 47-55 HRC for the male thread and a hardened layer depth of 1.5±0.1mm, and a surface hardness of 30-38 HRC for the female thread, with a hardened layer depth of 2mm or greater. For example, induction hardening equipment can be used to heat the male thread area to 880-920°C using high-frequency AC (e.g., 25-35kHz), concentrating the heating depth on the surface to achieve the required 1.5mm hardened layer. Cooling is then performed using a water-based quenching fluid or quenching oil. Low-temperature tempering (180-200°C for 1-2 hours) is then performed to eliminate quenching stresses and achieve a hardness of 47-55 HRC. Specific process parameters vary depending on the drill pipe material and are not specified here.

[0076] In some optional implementations of some embodiments, the threaded pipe may be obtained by the following steps: In the first step, a liquid nitrogen jet is used to cool the surface temperature of the male thread processing area on the partially quenched pipe to -50°C to -30°C for 3-5 minutes, resulting in a pre-cooled pipe. Cooling this area reduces cutting resistance during subsequent cutting, thereby increasing tool life. It also reduces thermal deformation during machining, improving thread dimensional accuracy to a certain extent.

[0077] The second step is to rough-turn the pre-cooled area of the pipe using a tool, creating a rough male thread. In practice, this can be done on a CNC lathe, with a cutting speed of 80-100 m / min, a feed rate of 0.15-0.25 mm / r, and a double-sided allowance of 0.8-1.2 mm. This removes most of the machining allowance, creating a rough thread prototype while also leaving allowance for subsequent finishing. It also avoids excessive tool load from cutting too much at once.

[0078] The third step is to heat the coarse male thread area of the pipe at a rate of 20-25°C / s to 200-250°C using an induction heater, producing a preheated coarse male thread pipe. In practice, a temperature sensor can be used to monitor the temperature of this coarse male thread area in real time, and heating is stopped when the target temperature is reached. Heating the coarse male thread area to 200-250°C can prevent local overheating to a certain extent, ensure temperature uniformity, and improve material toughness, preparing for the next high-temperature heating step.

[0079] The fourth step is to heat the preheated rough male threaded pipe to 450-480°C at a rate of 10-15°C / s using an induction heater and hold the temperature for 20-30 seconds to obtain the rough male threaded pipe. Heating the preheated rough male threaded pipe to 450-480°C further softens the material and eliminates processing stress. Holding the temperature for 20-30 seconds can achieve a certain degree of temperature uniformity to avoid local stress concentration. In practice, the induction heater and infrared thermometer can be used together to achieve heating and real-time monitoring functions. After holding the temperature for 20-30 seconds, the heated area is allowed to cool naturally to obtain the rough male threaded pipe.

[0080] The fifth step is to bore the female threaded area of the coarse male-threaded pipe to obtain the coarse-threaded pipe. In practice, the boring machine can be programmed through the CNC system to automatically adjust the spindle speed according to the depth. For example, when the boring depth is 0.3-0.5mm, the spindle speed is 800-1000 rpm. With each 0.2mm increase in boring depth, the spindle speed is controlled to decrease by 50-80 rpm to reduce cutting vibration to a certain extent.

[0081] In the sixth step, the rough male threads on the coarse-threaded pipe are whirled to produce a pipe with fine male threads. Whirling milling is the finishing process for the male threads. In practice, this rough male thread can be whirled using a whirling milling machine, continuously spraying coolant (such as an oil-water mixture and nano-diamond particles) into the cutting zone. The milling speed is controlled between 150 and 180 m / min to ensure a certain degree of thread profile accuracy.

[0082] In the seventh step, ultrasonic vibration-assisted thread milling is performed on the coarse female threads of the fine male threaded pipe to obtain the fine threaded pipe. This ultrasonic vibration-assisted thread milling can improve the machining accuracy and surface quality of the female threads and reduce tool sticking to a certain extent. In practice, an ultrasonic vibration device can be installed on the milling machine, with the tool connected to the vibration head. The ultrasonic amplitude is set to 8-12 μm and the frequency is set to 25-30 kHz. During milling, an axial pressure of 80-100 N is applied to improve milling stability.

[0083] In the eighth step, the male threads on the fine threaded pipe are placed in an ion nitriding furnace and treated for 90 to 120 minutes at a nitrogen potential of 0.8 to 1.2 to form a compound layer with a thickness of 20 to 30 μm, thereby obtaining a pipe with hardened male threads. The ion nitriding furnace can use the principle of glow discharge to allow nitrogen ions to adsorb, enrich, and penetrate the surface of the workpiece, combining with metal atoms to form a nitride layer, thereby achieving surface strengthening. In practice, the male threads can be placed in an ion nitriding furnace, evacuated, and then nitrogen gas is introduced. A DC voltage is applied to generate a glow discharge, and the nitrogen potential and time are controlled to complete the nitriding process, thereby obtaining the above-mentioned pipe with hardened male threads.

[0084] In the ninth step, a laser beam with a pulse width of 8-12ns and an energy density of 15-20J / cm² is used to scan the female thread flanks of the hardened male threaded pipe to obtain a threaded pipe. The 8-12ns short pulse laser precisely acts on the female thread flanks to reduce the size of the heat-affected zone. 2 The high energy density can cause the surface to micro-melt and re-solidify, forming a wear-resistant layer. In practice, a pulsed laser processing system can be used. The CNC system controls the laser head's movement speed and energy output, and the focused beam scans along the female thread flanks. This non-contact laser processing technique, utilizing laser energy to micro-process the female thread flanks without mechanical stress, can improve thread precision, thereby enhancing anti-seizure performance and the stability of drill pipe connections during practical applications.

[0085] The above-mentioned first to ninth steps, as an inventive point of an embodiment of the present disclosure, solve the technical problem of "poor wear resistance of drill pipe threads". The factors that lead to the poor wear resistance of drill pipe threads are as follows: the current drill pipe thread processing method lacks a surface strengthening process. If the above factors are solved, the effect of improving the wear resistance of drill pipe threads can be achieved. In order to achieve this effect, the present disclosure also provides a method for processing drill pipe threads. A compound layer with a certain thickness is formed on the basis of the male thread with a hardened layer through nitriding technology. The tooth side of the female thread is also scanned by a laser beam to cause micro-melting and re-solidification of the surface of the female thread to form a wear-resistant layer. Thereby, the wear resistance of the drill pipe thread is improved.

[0086] Step 106: Check the threaded pipe.

[0087] In some embodiments, the threaded tubular material may be inspected to obtain a finished drill pipe. The inspection may include visually inspecting the appearance of the threaded tubular material, for example, checking whether the threaded tubular material has obvious dents or bends, and whether the milled area has obvious burrs.

[0088] In some optional implementations of some embodiments, flaw detection equipment can be used to inspect the male and female threads on the threaded pipe. This flaw detection equipment can include ultrasonic flaw detection equipment, magnetic particle flaw detection equipment, eddy current flaw detection equipment, and the like. This flaw detection equipment can identify microscopic defects (such as cracks, pores, slag inclusions, and grinding burns) on or within the male and female threads. These microscopic defects may arise during turning, milling, heat treatment, and other processes. If not detected and corrected promptly, they may cause thread breakage during use of the drill pipe.

[0089] Step 107: Determine the threaded pipe that has passed the inspection as a finished drill pipe.

[0090] In some embodiments, threaded tubulars that pass inspection can be identified as finished drill pipe. Criteria for passing inspection may include the absence of significant dents or bends, the absence of noticeable burrs in the milled area (including the threaded area), and the absence of cracks, pores, slag inclusions, grinding burns, etc. on the threads as determined by flaw detection equipment.

[0091] Optionally, after obtaining the finished drill pipe, a wear-resistant coating may be added to the finished drill pipe by the following steps: The first step is to clean the surface of the drill rod body of the finished drill rod to obtain the cleaned drill rod. The above-mentioned rod body can refer to the drill rod excluding the male and female threads. Since the female thread is provided on the inner wall of the finished drill rod, the outer wall portion corresponding to the female thread can also be coated. Therefore, the portion that needs to be surface cleaned is the outer surface of the drill rod excluding the male thread on the finished drill rod. Figure 2 and Figure 3 , Figure 2 It is a schematic structural diagram of a drill rod obtained by processing according to some embodiments of the drill rod processing method disclosed herein. Figure 3 This figure shows a cross-sectional view of a drill rod produced according to some embodiments of the drill rod processing method disclosed herein. In practice, the rod body can be secured, the threads can be shielded with a high-temperature-resistant rubber sleeve, and the drill rod's outer surface can be shot-blasted to remove scale, grease, dust, and other debris. After shot-blasting, the outer surface of the drill rod can be further cleaned using sandblasting. The target surface roughness can be Ra ≤ 12.5 μm.

[0092] The second step is to add a wear-resistant coating to the rod body of the drill pipe after cleaning to obtain a reinforced drill pipe, wherein the thickness of the wear-resistant coating is 0.8~1.2mm. In practice, a wear-resistant coating can be added to the outer surface of the above-mentioned drill pipe by laser cladding. The specific coating material can be selected according to the actual working environment of the drill pipe. For example: in ordinary environments (neutral drilling fluid, medium and low abrasive formations), iron-based alloys can be used, and the hardness can be 50~55HRC; in high abrasive environments (hard rock, quartz sand formations), nickel-based alloys and tungsten carbide particles (mass ratio 8:2) can be used, and the hardness can be 60~65HRC; in highly corrosive environments (including S.C. Cobalt-based alloys can be used for drilling fluids. Furthermore, the cladding process can be divided into multiple steps. For example, a single cladding layer of 0.3-0.5 mm thick can be layered in 2-4 steps to a total thickness of 0.8-1.2 mm (each layer is cooled to below 100°C before the next one is clad). This ensures more complete melting of the coating powder.

[0093] Some embodiments of the present disclosure provide a drill rod processing method that can improve the connection strength between the rod body and the threaded end of the drill rod. Specifically, the reason why the connection strength between the rod body and the threaded end of most drill rods is low is that friction welding is commonly used to connect the rod body and the threaded end of the drill rod, and friction welding may produce welding defects such as pores and cracks. Based on this, some embodiments of the present disclosure provide a drill rod processing method, which includes using a cold-drawn steel pipe as a base material, and processing the two ends of the above-mentioned cold-drawn steel pipe by a forging process to obtain a forged pipe; placing the above-mentioned forged pipe in an annealing furnace for annealing treatment to obtain an annealed pipe, wherein the annealing temperature is 650~720℃, and the holding time is 2.5~3.5 hours; using a hydraulic straightening machine to perform multi-directional straightening on the above-mentioned annealed pipe to obtain a straightened pipe, wherein the straightness of the above-mentioned straightened pipe per meter is less than or equal to 0.5mm; using induction quenching equipment to perform local hardening on the above-mentioned straightened pipe The drill pipe is partially quenched to obtain a partially quenched pipe, wherein the surface hardness of the quenched area of the partially quenched pipe is between 23 and 28 HRC, and the thickness of the hardened layer is 6.5 ± 0.3 mm. A CNC lathe is used to machine male and female threads at both ends of the partially quenched pipe to obtain a threaded pipe, wherein the surface hardness of the male thread is between 47 and 55 HRC, the depth of the hardened layer is 1.5 ± 0.1 mm, and the surface hardness of the female thread is between 30 and 38 HRC, and the depth of the hardened layer is greater than or equal to 2 mm. The threaded pipe is then inspected, and the threaded pipe that passes the inspection is determined to be a finished drill pipe. By using cold-drawn steel pipe to produce threads through forging and milling, the process of welding the threaded end to the rod body is avoided, and the entire drill pipe is made of a single, complete steel pipe. This improves the connection strength between the rod body and the threaded end of the drill pipe.

[0094] In some embodiments, the drill rod processing device may include an annealing furnace, a CNC lathe, a hydraulic straightening machine, and an induction hardening device. The induction hardening device may include a sprayer and an auxiliary heater. The auxiliary heater may be an electromagnetic induction coil that can utilize the eddy current effect to heat the workpiece to temper the workpiece and reduce the quenching stress. The drill rod processing device is configured to perform the following steps: Figure 1 The steps in the corresponding embodiments.

[0095] Some embodiments of the present disclosure provide a drill rod processing device that can improve the connection strength between the rod body and the threaded end of the drill rod. Specifically, the reason why the connection strength between the rod body and the threaded end of most drill rods is low is that the rod body and the threaded end of the drill rod are currently connected by friction welding, and friction welding may produce welding defects such as pores and cracks. Based on this, some embodiments of the present disclosure provide a drill rod processing device, which includes an annealing furnace, a CNC lathe, a hydraulic straightening machine and an induction quenching device, wherein the above-mentioned induction quenching equipment includes a sprayer and an auxiliary heater; the above-mentioned drill rod processing device is configured to perform Figure 1 By forging and milling threads on a single cold-drawn steel pipe, welding the threaded end to the rod body is avoided. This improves the connection strength between the rod body and the threaded end, and enhances the durability of the drill rod.

[0096] The above descriptions are merely some preferred embodiments of the present disclosure and illustrate the underlying technical principles. Those skilled in the art should understand that the scope of the invention encompassed by the embodiments of the present disclosure is not limited to technical solutions formed by specific combinations of the aforementioned technical features. It also encompasses other technical solutions formed by any combination of the aforementioned technical features or their equivalents, without departing from the aforementioned inventive concept. For example, a technical solution formed by replacing the aforementioned features with (but not limited to) technical features with similar functions disclosed in the embodiments of the present disclosure.

Claims

1. A drill rod processing method comprising: A cold-drawn steel pipe is used as a base material, and both ends of the cold-drawn steel pipe are processed by a forging process to obtain a forged pipe; Placing the forged pipe into an annealing furnace for annealing to obtain an annealed pipe, wherein the annealing temperature is 650-720° C. and the holding time is 2.5-3.5 hours; Using a hydraulic straightening machine to perform multi-directional straightening on the annealed pipe to obtain a straightened pipe, wherein the straightness of the straightened pipe per meter is less than or equal to 0.5 mm; The straightened pipe is subjected to local quenching treatment using an induction quenching device to obtain a locally quenched pipe, wherein the surface hardness of the quenched area of the locally quenched pipe is 23-28 HRC, and the thickness of the hardened layer is 6.5±0.3 mm; A CNC lathe is used to process male and female threads on both ends of the partially quenched pipe to obtain a threaded pipe, wherein the surface hardness of the male thread is 47-55 HRC, the hardened layer depth is 1.5±0.1 mm, and the surface hardness of the female thread is 30-38 HRC, and the hardened layer depth is greater than or equal to 2 mm; Calibrate the threaded pipe; The threaded pipes that have passed the inspection are identified as finished drill pipes.

2. The method according to claim 1, wherein The cold-drawn steel pipe is used as a base material, and both ends of the cold-drawn steel pipe are processed by a forging process to obtain a forged pipe, including: The two ends of the cold-drawn steel pipe are upset using a forging die to obtain a forged pipe, wherein the outer diameters of the two ends of the forged pipe reach 110% to 120% of the target size, and the inner diameter is reduced to 85% to 90% of the target size.

3. The method according to claim 1, wherein The forged pipe is placed in an annealing furnace for annealing to obtain the annealed pipe, comprising: A pipe support is provided inside the annealing furnace; Placing the forged pipes on the pipe support, wherein the spacing between adjacent forged pipes is 80-120 mm; introducing a protective gas into the annealing furnace; Raising the temperature in the annealing furnace to 650-720° C. at a rate of less than or equal to 45° C. / hour; Control the holding time to 2.5-3.5 hours to obtain a pre-annealed pipe; Cooling the pre-annealed tube to 450° C. to obtain a pre-cooled tube; The pre-cooled pipe is air-cooled to room temperature to obtain an annealed pipe.

4. The method according to claim 1, wherein The method of using a hydraulic straightening machine to perform multi-directional straightening on the annealed pipe to obtain the straightened pipe comprises: Selecting a suitable fixture according to the diameter of the tube after annealing; Installing the selected fixture on the hydraulic straightening machine; Installing the annealed pipe into the hydraulic straightening machine; Inspecting the annealed pipe after being processed by the hydraulic straightening machine; The annealed pipes that pass the inspection are determined to be straightened pipes.

5. The method according to claim 1, wherein The method of using a CNC lathe to respectively process male threads and female threads on both ends of the partially quenched pipe to obtain a threaded pipe comprises: Controlling a numerically controlled lathe to turn one end of the partially quenched pipe to obtain a male thread; Boring the other end of the partially quenched pipe to obtain a female thread processing area; Performing thread milling on the female thread processing area to obtain the female thread; The obtained male and female threads are quenched to obtain threaded pipes.

6. The method according to claim 1, wherein The calibrating of the threaded pipe comprises: The male thread and the female thread are inspected using flaw detection equipment.

7. The method according to claim 1, wherein The method further comprises: Cleaning the surface of the drill rod body to obtain a cleaned drill rod; After the cleaning, a wear-resistant coating is added to the rod body of the drill rod to obtain a reinforced drill rod, wherein the thickness of the wear-resistant coating is 0.8-1.2 mm.

8. The method according to claim 1, wherein Before locally quenching the straightened pipe using an induction quenching device to obtain a locally quenched pipe, the method further includes: Installing a vibrator on the straightened pipe; The vibrator is controlled to vibrate at a preset frequency for a preset time to obtain a vibrated pipe, wherein the preset time is greater than or equal to 40 minutes, and the preset frequency is 80-90% of the natural frequency of the straightened pipe.

9. The method according to claim 1, wherein The method of using an induction hardening device to perform a local quenching treatment on the straightened pipe to obtain a locally quenched pipe comprises: Controlling the induction quenching equipment to preheat the target quenching area of the straightened pipe to 550-600° C. using 1.2-1.8 kHz alternating current to obtain a preheated pipe; The preheated pipe is kept warm for 30 to 45 seconds to obtain an insulated pipe; Controlling the induction hardening equipment to use 25-35 kHz alternating current to raise the temperature of the target quenching area of the insulated pipe to 880-920° C., thereby obtaining a fully heated pipe; Controlling the sprayer to spray a coolant at a temperature of 20-25° C. at a spray pressure of 0.25-0.35 MPa to obtain a cooled pipe, wherein the spray angle of the sprayer is 30-45° with the axis of the completely heated pipe, and the continuous spraying time is 8.5-10.5 seconds; An auxiliary heater is arranged 50 mm outside the quenching area, and tempering is performed at 200-250°C to obtain a locally quenched pipe.

10. A drill rod processing device, comprising an annealing furnace, a CNC lathe, a hydraulic straightening machine and an induction hardening device, wherein: The induction quenching equipment includes a sprayer and an auxiliary heater; The drill rod processing device is configured to perform the method according to any one of claims 1 to 9.

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