Method and system for preparing low-flow-resistance corrosion-resistant oil conveying pipe from hot-rolled stainless steel

Abstract

The invention discloses a method and a system for preparing a low-flow-resistance corrosion-resistant oil conveying pipe by using hot-rolled stainless steel. The system mainly comprises a customized nanosecond laser and galvanometer system, an industrial robot, an auxiliary power supply, a PLC control system and an industrial personal computer which are arranged in front of a closed pass of a cold bending production line. The adopted technical method comprises the steps that after an incoming material signal is detected, plate conveying is paused, a robot acts to a designated point position to complete laser focusing, the wrist of the robot rotates by a circle, and laser micro-nano structure machining of a specific grid pattern is completed once within a certain rolling direction distance of the plate. Then the robot returns to the initial pose, and the plate conveying continues; and the steps are repeated, and preparation of the inner surface micro-nano structure of the whole roll of plate is completed. And the laser micro-nano machining preposition and subsequent procedures are kept unchanged. The laser micro-nano machining is applied to enable the inner surface of the hot-rolled stainless steel oil conveying pipe to have low flow resistance and enhance corrosion resistance, the problems that cost is too high and organic pollution exists are solved, and the method has the advantages of being small in investment, low in cost, easy to operate and the like.

Description

Technical Field

[0001] The present invention relates to the field of metal processing and forming, and particularly to a method and system for preparing a low-flow-resistance and corrosion-resistant oil transmission pipe using hot-rolled stainless steel. Background Art

[0002] In the petroleum, natural gas, and chemical industries, the performance of oil transmission pipelines directly affects the transportation efficiency, energy consumption, and operating costs. Traditional oil transmission pipelines mostly use carbon steel or ordinary stainless steel, but there are the following problems: high flow resistance leads to increased energy consumption. The inner surface of traditional pipelines has a relatively high roughness, resulting in a large fluid friction resistance. Especially during long-distance transportation, the pumping energy consumption increases significantly; existing technologies usually rely on mechanical polishing or electrochemical polishing to reduce roughness, but the cost is high and it is not suitable for large-diameter pipelines; insufficient corrosion resistance. Carbon steel pipelines rely on anti-corrosion coatings or cathodic protection, but the coatings are easily damaged and the maintenance cost is high; ordinary stainless steel (such as 304) is prone to pitting corrosion and stress corrosion cracking (SCC) in oils containing H2S, CO2, or Cl⁻, affecting the service life.

[0003] Hot-rolled stainless steel pipes (such as 316L and 2205 duplex steel) are widely used in large-diameter pipelines due to their low cost and good formability, but their surfaces have defects such as oxide scales and microcracks. Direct use will exacerbate the flow resistance and corrosion risks. Existing pickling and passivation processes can only partially improve the surface quality and cannot meet the requirements of low flow resistance and enhanced corrosion resistance. Composite coating technologies (such as plastic lining) can reduce the flow resistance, but have poor heat resistance and are prone to delamination, and are not suitable for high-pressure working conditions; electrolytic polishing can reduce the flow resistance, but is only applicable to small-diameter pipes and has high energy consumption.

[0004] A superhydrophobic surface refers to a surface with a water contact angle greater than 150° and a rolling angle less than 10°, which has excellent properties such as self-cleaning, anti-corrosion, and anti-icing. An oil and gas transmission stainless steel pipe with a superhydrophobic inner surface will have excellent properties of low flow resistance and super corrosion resistance. Traditional methods for preparing superhydrophobic surfaces usually require pretreatment of the substrate, such as polishing and chemical etching, to obtain a smooth surface, and then modification with low-surface-energy substances. However, these methods have complex processes, high costs, and it is difficult to achieve superhydrophobic properties on rough surfaces. Therefore, it is difficult for the existing technology to directly manufacture excellent low-cost stainless steel oil and gas transmission pipelines with low flow resistance and super corrosion resistance from hot-rolled stainless steel without polishing and grinding processes. Therefore, it is particularly urgent to develop a practical technology for directly manufacturing excellent low-cost stainless steel oil and gas transmission pipelines with low flow resistance and super corrosion resistance from hot-rolled stainless steel without a polishing process.

[0005] The above content is only used to assist in understanding the technical solution of the present invention and does not represent an admission that the above content is prior art.

[0006] At present, a variety of methods for reducing pipeline flow resistance have been developed. For example, the prior art "Method and Device for Reducing Flow Resistance in a Pipeline" (CN98809887.3) discloses a method and device for reducing flow resistance in a pipeline. By applying an electric field to the pipeline wall, the flow resistance is reduced, and the field strength is adjusted according to the measurement of the flow area before and after the part where the fluid or powder is subjected to the electric field. The fluid can be a pure fluid, a corrosive fluid, or a fluid containing impurities in particulate form. This method can effectively reduce the flow resistance, but specific equipment needs to be added during the use of the pipeline, consuming additional energy, and the pipeline itself does not have the characteristic of low flow resistance. The prior art "Water Supply Pipe with Reduced Flow Resistance" (CN201920393932.5) discloses a water supply pipe with reduced flow resistance. By arranging an inclined filter plate inside the pipeline body, the filter plate can filter impurities in the fluid, leaving them on one side of the filter plate, and then the impurities can be pumped out by a sewage suction pump to prevent the filter plate from being blocked. At the same time, the filter plate is slidably arranged in the chute on the pipeline body, and the first damping spring and the second damping spring play a dual damping role, driving the filter plate to slide in the chute, making the flow velocity of the flowing liquid in the pipeline tend to be stable. A superhydrophobic coating is fixedly arranged on the inner wall of the inner pipeline, which is beneficial to improving the flatness of the inner surface of the pipeline and reducing the friction force with the water flow to reduce the flow resistance. This pipeline can reduce the flow resistance, but its design is complex, requiring more structural components to be added, and it is not suitable for application as an oil pipeline. These methods require more modifications to the pipeline structure, or more equipment needs to be added during the use of the pipeline, or the cost of using the pipeline is high, and they cannot be applied to oil pipelines.

[0007] Preparing superhydrophobic textures on the inner surface of oil pipelines is an effective strategy to reduce flow resistance. Currently, there are various methods for preparing superhydrophobic surfaces, such as electrochemical deposition, vapor deposition, chemical etching, etc. However, these methods all have their own disadvantages. For example, the prepared hydrophobic textures have poor mechanical stability, the preparation process causes great environmental pollution, and the preparation cost is relatively high. Preparing superhydrophobic surfaces by laser etching can obtain superhydrophobic textures with relatively high stability and cause less environmental pollution. For example, in the prior art "Method for Preparing Metal Superhydrophobic Surface and Laser Processing Equipment" (CN202111173206.0), after at least two laser scans of the metal to be processed along the scanning path by controlling the laser emitter using laser parameters, a superhydrophobic surface can be obtained, solving the problem of preparing metal superhydrophobic surfaces without adding fluorides and avoiding environmental pollution of the metal. However, this technology clearly requires cleaning and preprocessing of the metal surface of the metal to be processed before laser processing, otherwise a superhydrophobic surface cannot be generated, and this technology requires at least two laser scans for processing, increasing the processing cost. Another example is the prior art "Method for Preparing Superhydrophobic Surface by Laser Shock Imprinting of Micro-Nano Particles on Aluminum Alloy Surface" (CN202111249205.X). By preprocessing the aluminum alloy surface, the surface roughness is ≤0.05 μm; after mixing micro-nano hard particles and micro hard particles, they are uniformly pre-coated on the back of the absorption layer on the aluminum alloy surface; short-pulse laser is used to shock the absorption layer coated with the mixed hard particles, so that the mixed hard particles are imprinted on the aluminum alloy surface; ultrasonic cleaning is used to remove the mixed hard particles on the aluminum alloy surface, and after reducing the surface energy of the aluminum alloy surface by chemical modification, a superhydrophobic functional surface composed of micro-nano multi-level pit structures is obtained. This technology can produce a reliable superhydrophobic aluminum surface, but the aluminum alloy surface also needs to be preprocessed before laser processing, and the surface roughness needs to be ≤0.05 μm; this method uses chemical modification to reduce the surface energy of the aluminum alloy surface, which will cause relatively large environmental pollution. Although the above various methods can effectively prepare superhydrophobic metal surfaces, they all need to preprocess the metal surface in advance, with cumbersome procedures and relatively high costs, resulting in the inability to directly use hot-rolled stainless steel strip to prepare low-flow-resistance oil pipelines without cumbersome surface pretreatment processes. Therefore, it is difficult to be applied in the field of oil pipelines with large usage and sensitive to costs, and some technologies have relatively large environmental pollution problems, which do not meet the requirements of today's society. In addition, during the manufacturing process of round pipes, the diameter specifications of round pipes vary greatly, and the strip is prone to vibration, making it difficult to frequently focus during traditional laser scanning, which limits the application of laser processing technology in the field of oil pipelines. Summary of the Invention

[0008] The main object of the present invention is to provide a method and system for directly using hot-rolled stainless steel to prepare a low-flow-resistance corrosion-resistant oil pipeline, which has a simple process, low cost, and aims to solve the following problems: hot-rolled strip with a relatively low price cannot be directly used without surface pretreatment and must go through processes such as pickling, polishing, and grinding; the traditional superhydrophobic surface preparation methods available for manufacturing low-flow-resistance corrosion-resistant oil pipelines require pretreatment of the substrate (such as polishing, chemical etching, etc.) and modification with low-surface-energy substances, which have cumbersome processes, high costs, and environmental pollution caused by the modification with low-surface-energy substances.

[0009] To achieve the above object, the technical solution adopted by the present invention is as follows: In the first aspect, a system for directly using hot-rolled stainless steel to prepare a low-flow-resistance corrosion-resistant oil pipeline, the system mainly includes a customized nanosecond laser and a galvanometer system, an industrial robot, an auxiliary power supply, a PLC control system, and an industrial control computer: the laser and galvanometer system installed on the wrist of the industrial robot; the industrial robot and its control cabinet, teach pendant, control software, etc.; the power supply used to supply power to each device of the system; the PLC control system used to control the action time, start and stop, predetermined actions, etc., including components such as a PLC and an auxiliary photoelectric detection switch; the industrial control computer is used to control the laser and the entire set of equipment to act according to the set process; the control software of the entire system and the laser control software. The load capacity of the robot meets the wrist load working requirements of the working components of the laser, and the cross-sectional size of the robot's forearm is smaller than the opening transverse size before the round tube closing pass.

[0010] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the purpose and beneficial effects of the present invention can be better achieved.

[0011] As a preferred technical solution, the laser is a nanosecond laser, and its supporting software supports external program control.

[0012] As a preferred technical solution, it is characterized in that the entire set of systems is set after the last pass before the sheet material is about to be closed into a round tube during cold bending forming, and the same set of rolls (including the lower roll, left and right side rolls, but not including the upper roll) as the previous pass is added before the next pass, and the elevation and lateral position of the added rolls are the same as those of the previous pass.

[0013] Second aspect, a method for directly preparing a low-flow-resistance corrosion-resistant oil pipeline using hot-rolled stainless steel: After the optoelectronic detection switch detects the incoming material signal, the industrial control computer sends a signal to the upper computer on the production line, and the upper computer controls the suspension of the sheet / tape conveying. The industrial control computer sends a signal to the PLC control system; according to the previously determined position of the sheet / tape, the PLC sends a signal to the robot, and the robot moves to the specified point to complete the laser focusing; the PLC sends a signal to the robot, the robot reaches the set position, the robot wrist rotates one week, and while rotating, the industrial control computer sends a laser control signal to the laser supporting software to make the laser work according to the best parameters determined by prior experiments, and a laser micro-nano structure processing of a specific grid pattern is completed within a certain rolling direction distance of the sheet / tape. Subsequently, the robot returns to the initial pose, the sheet / tape conveying continues, the sheet / tape moves forward a certain distance, and enters the next surface processing area processing cycle. Repeating like this, the preparation of the micro-nano structure on the inner surface of the entire coil of sheet / tape is completed, and the processes such as the front position of the laser micro-nano processing process and the subsequent bending passes remain unchanged. The initial surface state of the hot-rolled stainless steel is not limited, the steel type is not limited, the thickness is not limited, the width is not limited, and the length is not limited.

[0014] As a preferred technical solution, the laser processing parameters are: pulse width 10 - 800 ns, repetition frequency 10 - 100 kHz, scanning speed 1 - 5000 mm / s, laser energy density 1 - 10 J / cm², and the number of laser scanning processing times is one.

[0015] As a preferred technical solution, the laser processing specific grid pattern is an equally spaced square pattern, and the adjacent straight line spacing is between 0.001 - 0.2 mm.

[0016] Third aspect, a low-flow-resistance corrosion-resistant pipe product prepared using the above-mentioned hot-rolled stainless steel, wherein the pipe product is prepared by using the above-mentioned method or system.

[0017] Fourth aspect, the above-mentioned low-flow-resistance corrosion-resistant pipe product is used for oil transportation and water transportation.

[0018] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art: 1. For the method and system for preparing a low-flow-resistance corrosion-resistant oil pipeline using hot-rolled stainless steel according to the present invention, due to the adoption of a laser system guided by a robot, it is much more convenient to apply laser focusing on the round pipe production line. Moreover, since the upper computer can obtain production information from the production line, the center position of the round pipe is easily obtained, and through system linkage, the online focusing of the laser can be easily realized, thus creating conditions for subsequent laser processing.

[0019] 2. The method and system for preparing a low-flow-resistance corrosion-resistant oil transmission pipe using hot-rolled stainless steel according to the present invention set up the entire system after the last pass before the sheet material is about to close into a round pipe, and add the same roll configuration as the previous pass (including the lower roll, left and right side rolls, but not including the upper roll) before the next pass. The added roll elevation and lateral position are the same as those of the previous pass, which can prevent the rolls in the subsequent closing pass from contacting or basically not contacting the inner surface of the round pipe, thus avoiding mechanical damage to the superhydrophobic surface during the production process.

[0020] 3. The method and system for preparing a low-flow-resistance corrosion-resistant oil transmission pipe using hot-rolled stainless steel according to the present invention can directly produce using rough hot-rolled strip steel as raw material without surface pretreatment due to the use of laser processing parameters obtained based on experiments, which can not only significantly reduce the raw material cost but also greatly reduce the processing cost.

[0021] 4. The method and system for preparing a low-flow-resistance corrosion-resistant oil transmission pipe using hot-rolled stainless steel according to the present invention only require one laser scan for the same metal surface area, which greatly improves the operation efficiency and significantly reduces the laser processing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of the system for preparing a low-flow-resistance corrosion-resistant oil transmission pipe using hot-rolled stainless steel according to the present invention. In the drawings, the reference numerals are: two added side rolls 1, rolled piece 2, robot 3, robot support base 4, laser and galvanometer system 5, roll of the previous pass 6. Figure 2 It is a schematic diagram of the relationship of the control and software system according to the present invention, mainly including a host computer, a PLC system, a laser, and a robot: the host computer controls the laser and galvanometer system through a laser control system to control the laser processing; the host computer controls the PLC and the robot through a process control system; the PLC system directly controls the robot actions; the robot controls the laser pose through wrist actions. Figure 3 It is a schematic diagram of a specific grid pattern of laser scanning according to the present invention. Figure 4 It is an optical micrograph of the surface of a hot-rolled stainless steel material processed by the method according to the present invention. Figure 5 It is a comparison test picture of the contact angle of the inner surface of the rolled piece in Example 1: Figure 5 (a) is a test picture of the contact angle of the surface without being treated by this method; Figure 5 (b) is a test picture of the contact angle of the surface treated by this method and system. Figure 6 It is a comparison test picture of the contact angle of the inner surface of the rolled piece in Example 2: Figure 6 (a) is a test picture of the contact angle of the surface without being treated by this method; Figure 6(b) is the surface contact angle test diagram processed by the present method and system. Figure 7 It is the comparison test picture of the inner surface contact angle of the rolled piece in Example 3: Figure 7 (a) is the surface contact angle test diagram without being processed by the present method; Figure 7 (b) is the surface contact angle test diagram processed by the present method and system. Specific implementation manners

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0023] Embodiment 1: A method and system for preparing a low-flow-resistance and corrosion-resistant oil transmission pipe from hot-rolled stainless steel. In this embodiment, the rolled piece is a hot-rolled stainless steel strip. The diameter of the finished pipe is 400 mm, the steel grade is 304 (06Cr19Ni10), the width of the sheet material is 1250 mm, and the thickness is 10 mm. After the scale is removed conventionally, the initial surface roughness Ra is about 5 μm when cold bending. The method and system for preparing a low-flow-resistance and corrosion-resistant oil transmission pipe from hot-rolled stainless steel are as follows: In Example 1, as Figure 1 shown, the system for preparing a low-flow-resistance and corrosion-resistant oil transmission pipe from hot-rolled stainless steel (mainly referring to the two additional side rollers 1, robot 3, robot support base 4, laser and galvanometer system 5, upper computer, etc. in the figure) is arranged behind the previous pass rolls. When the rolled piece 2 moves forward to a certain position after the rolls 6, the attached photoelectric detection switch detects the head of the rolled piece 2. At this time, the attached photoelectric detection switch sends a signal to the PLC, and the PLC feeds back the incoming material signal to the upper computer. The upper computer determines the laser processing parameters and the robot position according to the pre-determined incoming material rolling information, and then the upper computer sends instructions to the PLC and the conveying roll control system (the control system relationship is as Figure 2 shown). The conveying roll control system controls the conveying rolls to stop conveying the rolled piece. At the same time, the PLC sends instructions to the robot, and the robot reaches the processing position according to the pre-determined pose and specified path to prepare for operation. After the robot is ready for operation, the robot wrist rotates at the pre-determined speed determined by the upper computer. At the same time, the upper computer sends a signal to the laser and galvanometer system through the laser control software, and the laser scans along the inner surface of the circular pipe. The scanning pattern is a square grid (as Figure 3As shown in the figure, the grid line spacing is 30 μm, the laser pulse width is 100 ns, the repetition frequency is 20 kHz, the scanning speed is 1000 mm / s, the laser energy density is 3 J / cm², and the number of laser scanning processes is one. After the wrist rotates one week, this laser scanning ends. The host computer sends a signal to the conveyor roller control system. The conveyor roller rotates, and the rolled piece moves forward a set distance and then stops. The part of the rolled piece that has been laser scanned continues to enter the subsequent passes for production. Repeat step 2 again until this scan is completed. Continuously repeat steps 2 and 3 until the entire inner surface of the rolled piece is completely laser processed, that is, the processing of this stainless steel oil pipeline is completed. As Figure 4 shown, it is a photo of the inner surface of the rolled piece in Example 1 under a low-power optical microscope. It can be seen that the grid-like groove spacing is consistent and the morphology is clear. As Figure 5 shown, it is a comparison test picture of the contact angle of the inner surface of the rolled piece in Example 1: Among them Figure 5 (a)is the surface contact angle test diagram of the inner surface of the original steel pipe without being treated by this method for pure water test, and the contact angle is about 37.6°; Figure 5 (b)is the surface contact angle test diagram of the inner surface of the low-flow-resistance steel pipe treated by this method and system for pure water test, and the contact angle is about 150.9°. It can be seen that after being treated by this method and system, the contact angle of the inner surface of the steel pipe increases significantly, presenting a superhydrophobic state. It can be predicted that the inner surface of the steel pipe in Example 1 treated by this method and system will have lower flow resistance and better corrosion resistance.

[0024] Example 2: A method and system for preparing a low-flow-resistance and corrosion-resistant oil pipeline from hot-rolled stainless steel. The rolled piece in this example is a hot-rolled stainless steel strip. The finished pipe diameter is 300 mm, the steel grade is 316L (022Cr17Ni12Mo2), the sheet width is 1050 mm, and the thickness is 5 mm. After the scale is regularly removed, the initial surface roughness Ra is about 4 μm during cold bending. The method and system for preparing a low-flow-resistance and corrosion-resistant oil pipeline from hot-rolled stainless steel are as follows: In Example 2, as Figure 1 shown, the system for preparing a low-flow-resistance and corrosion-resistant oil pipeline from hot-rolled stainless steel (mainly referring to the two additional side rollers 1, robot 3, robot support 4, laser and galvanometer system 5, host computer, etc. in the figure) is set behind the previous pass rollers. When the rolled piece 2 moves forward to a certain position after the rollers 6, the attached photoelectric detection switch detects the head of the rolled piece 2. At this time, the attached photoelectric detection switch sends a signal to the PLC, and the PLC feeds back the incoming material signal to the host computer. The host computer determines the laser processing parameters and the robot position according to the pre-determined incoming material rolling information, and then the host computer sends instructions to the PLC and the conveyor roller control system (the control system relationship is as Figure 2As shown in the figure, the conveying roller control system controls the conveying roller to stop conveying the rolled piece. At the same time, the PLC sends an instruction to the robot, and the robot reaches the processing position according to the pre-set pose and the specified path to prepare for starting the operation. After the robot is ready for operation, the robot wrist rotates at a predetermined speed determined by the host computer. At the same time, the host computer sends a signal to the laser and galvanometer system through the laser control software, and the laser scans along the inner surface of the circular tube. The scanning pattern is a square grid, the straight line spacing of the grid is 40 μm, the laser pulse width is 70 ns, the repetition frequency is 50 kHz, the scanning speed is 1500 mm / s, the laser energy density is 3.5 J / cm², and the number of laser scanning processes is one. After the wrist rotates one week, this laser scanning ends. The host computer sends a signal to the conveying roller control system, the conveying roller rotates, and the rolled piece stops after moving forward a set distance. The part of the rolled piece scanned by the laser continues to enter the subsequent passes for production. Repeat step 2 again until this scan is completed. Continuously repeat steps 2 and 3 until the entire inner surface of the rolled piece is laser processed, that is, the processing of this stainless steel oil pipeline is completed. As Figure 6 shown, it is a comparison test picture of the contact angle of the inner surface of the rolled piece in Example 2: Among them Figure 6 (a)is a surface contact angle test diagram of the pure water test on the inner surface of the original steel pipe without being treated by this method, and the contact angle is about 58.3°; Figure 6 (b)is a surface contact angle test diagram of the pure water test on the inner surface of the low-flow-resistance steel pipe treated by this method and system, and the contact angle is about 151.9°. It can be seen that after being treated by this method and system, the contact angle of the inner surface of the steel pipe increases significantly, presenting a super-hydrophobic state. Therefore, it can be predicted that the inner surface of the steel pipe in Example 2 treated by this method and system will have lower flow resistance and better corrosion resistance.

[0025] Example 3: A method and system for preparing a low-flow-resistance and corrosion-resistant oil pipeline with hot-rolled stainless steel. The rolled piece in this example is a hot-rolled stainless steel strip, the finished pipe diameter is 500 mm, the steel grade is duplex stainless steel 2205(022Cr23Ni5Mo3N), the width of the sheet material is 1100 mm, the thickness is 12 mm, and the initial surface roughness Ra is about 6 μm when cold-bent after conventional removal of scale. The method and system for preparing a low-flow-resistance and corrosion-resistant oil pipeline with hot-rolled stainless steel are: Implement Example 1, as Figure 1As shown in the figure, the system for preparing a low-flow-resistance corrosion-resistant oil pipeline using hot-rolled stainless steel (mainly referring to the two additional side rollers 1, robot 3, robot support base 4, laser and galvanometer system 5, upper computer, etc. in the figure) is arranged behind the previous rolling mill rolls. When the rolled piece 2 moves forward to a certain position after the rolling mill rolls 6, the auxiliary photoelectric detection switch detects the head of the rolled piece 2. At this time, the auxiliary photoelectric detection switch sends a signal to the PLC, and the PLC feeds back the incoming material signal to the upper computer. The upper computer determines the laser processing parameters and the robot position according to the pre-determined incoming material rolling information, and then the upper computer sends instructions to the PLC and the conveying roller control system. The conveying roller control system controls the conveying rollers to stop conveying the rolled piece (the control system relationship is as Figure 2 shown). At the same time, the PLC sends instructions to the robot, and the robot reaches the processing position according to the pre-determined pose and the specified path and prepares to start the operation. After the robot is ready to operate, the robot wrist rotates at the pre-determined speed determined by the upper computer. At the same time, the upper computer sends a signal to the laser and galvanometer system through the laser control software, and the laser scans along the inner surface of the circular tube. The scanning pattern is a square grid, the linear distance between the grid lines is 80 μm, the laser pulse width is 60 ns, the repetition frequency is 30 kHz, the scanning speed is 2000 mm / s, the laser energy density is 4 J / cm², and the number of laser scanning processing times is one. After the wrist rotates one week, this laser scanning ends. The upper computer sends a signal to the conveying roller control system, the conveying rollers rotate, and the rolled piece stops after moving forward a set distance. The part of the rolled piece scanned by the laser continues to enter the subsequent passes for production. Repeat step 2 again until this scan is completed. Continuously repeat steps 2 and 3 until the entire inner surface of the rolled piece is laser processed, that is, the processing of this stainless steel oil pipeline is completed. As Figure 7 shown, it is a comparison test picture of the contact angle of the inner surface of the rolled piece in Example 3: Among them Figure 7 (a) is the surface contact angle test diagram of the pure water test on the inner surface of the original steel pipe without being treated by this method, and the contact angle is about 56.5°; Figure 7 (b) is the surface contact angle test diagram of the pure water test on the inner surface of the low-flow-resistance steel pipe treated by this method and system, and the contact angle is about 147.2°. It can be seen that after being treated by this method and system, the contact angle of the inner surface of the steel pipe increases significantly, showing a quasi-superhydrophobic state. Therefore, it can be predicted that the inner surface of the steel pipe in Example 3 treated by this method and system will have lower flow resistance and better corrosion resistance.

[0026] References [1]AMRITA H, GOYATB M S, JITENFRA K P, et al. A review onfundamentals, constraints and fabrication techniques of superhydrophobiccoatings [J]. Progress in Organic Coatings, 2020, 142: 105557. [2]XU Da, XIAO Zhen, YU Xinquan, et al. Preparation and antiicingcharacteristics of multifunctional hydrophobic / superhydrophobic compositecoating [J]. Acta Materiae Compositae Sinica,2022,39(3):1102-1109(inChinese). [3]YUAN G, LIU Y W, NGO C V, et al. Rapid fabrication ofanticorrosion and self-healing superhydrophobic aluminum surfaces throughenvironmentally friendly femtosecond laser processing [J]. Optics Express,2020,28(24):35636- 35650. [4]Wang Zhaolin, Li Xiangyun, Song Haipeng, et al. Preparation and properties of superhydrophobic surfaces on 2A12 aluminum alloy substrate [J]. Materials Science & Technology, 2023, 31(2): 83-89. [5]Sun Xiaoyu, Sun Shufeng, Wang Haitao, et al. Preparation and process optimization of superhydrophobic surfaces on 7075 Al alloy based on picosecond laser [J]. Acta Compositae Sinica, 2023, 40(6): 3583-3593. [6]XU Guangming, LIU Ping, LIU An, et al. Mechanically stablesuperhydrophobic surfaces constructed by laser surface texturing and micro-arc oxidation of TC4 alloy prepared based on SLM [J]. Materials Chemistry andPhysics, 2024, 325: 129791. [7]WU Y L, WANG Z D, YANG J Y, et al. Designing superhydrophobicrobotic surfaces: Self-cleaning, high-grip impact, and bacterial repelling[J]. Colloids&Surfaces A Physicochemical and Engineering Aspects,2021,629:127444. [8]SABA G M, HaAMIDREZA P, ALI E. Multifunctional superhydrophobicsurfaces [J]. Advances in Colloid and Interface Science, 2021, 290: 102397. [9]SANJEEV P D, MOHAMED A S A, SANJAY S L, et al. Recent Advances indurability of superhydrophobic self-cleaning technology: A critical review[J]. Progress in Organic Coatings, 2020, 138: 105381。

Claims

1. A method and system for preparing a low flow resistance and corrosion resistant oil pipeline using hot-rolled stainless steel, characterized in that The system is mainly composed of customized nanosecond laser and galvanometer, industrial robot, auxiliary gas source and power supply, PLC control system, industrial computer: nanosecond laser and galvanometer installed on the wrist of industrial robot; auxiliary gas source for nanosecond laser and power supply for the whole system including robot and laser; industrial robot and its control cabinet, teaching pendant, control software; PLC control system for controlling action time, start and stop, etc., including PLC, photoelectric detection switch and other components; industrial computer for controlling laser and the whole set of equipment according to set process action; control software of the whole system and laser control software. In cold bending forming, the whole system is set after the last pass before the sheet is about to be closed to become a round tube, and the same roller configuration as the previous pass (including lower roller, left and right side rollers, but not including upper roller) is added before the next pass, and the height and lateral position of the added roller are the same as the previous pass.

2. A method and system for preparing a low flow resistance and corrosion resistant oil pipeline using hot-rolled stainless steel, characterized in that The method is as follows: after the photoelectric detection switch detects the incoming signal, the industrial computer sends a signal to the upper computer of the production line, the upper computer controls the sheet / strip conveying to pause, and the industrial computer sends a signal to the PLC control system; according to the pre-determined sheet / strip position, the PLC sends a signal to the robot, and the robot moves to the specified point to complete the laser focusing; the PLC sends a signal to the robot, the robot reaches the set position, and the robot wrist rotates one circle. While rotating, the industrial computer sends a laser control signal to the laser supporting software to make the laser work according to the optimal parameters determined in advance by the experiment, and completes a laser micro-nano structure processing of a specific grid pattern within a certain rolling distance of the sheet / strip. Then the robot returns to the initial position, the sheet / strip conveying continues, the sheet / strip moves forward a distance, and enters the next surface processing area processing cycle. In this way, the inner surface micro-nano structure preparation of the whole roll of sheet / strip is completed, and the laser micro-nano processing process front and subsequent bending pass processes remain unchanged.

3. The method and system for preparing a low flow resistance and corrosion resistant oil pipeline using hot rolled stainless steel according to claim 1, characterized in that The whole system is set up after the last pass before the sheet is closed to become a round tube, and before the next pass, the same roller configuration as the previous pass (including the lower roller, left and right side rollers, but excluding the upper roller) is added. The height and lateral position of the added rollers are the same as those of the previous pass.

4. The system for preparing a low flow resistance and corrosion resistant oil pipeline using hot-rolled stainless steel according to claim 1, characterized in that The load capacity of the robot must meet the working requirements of the wrist load such as the laser working parts, and the cross-sectional size of the robot's forearm must be smaller than the lateral size of the opening of the round tube before the closing pass.

5. The system for preparing a low flow resistance and corrosion resistant oil pipeline using hot-rolled stainless steel according to claim 1, characterized in that The laser is a nanosecond laser, and its supporting software supports external program control.

6. The method and system for preparing a low flow resistance and corrosion resistant oil pipeline using hot rolled stainless steel according to claims 1 and 2, characterized in that The hot-rolled stainless steel has no restrictions on initial surface state, steel type, thickness or width.

7. The method for preparing a low flow resistance and corrosion resistant oil pipeline using hot rolled stainless steel according to claim 2, characterized in that The laser processing parameters are: pulse width 10-800 ns, repetition frequency 10-200 kHz, scanning speed 1-5000 mm / s, laser energy density 1-10 J / cm², and laser scanning processing times are once.

8. The method for preparing a low flow resistance and corrosion resistant oil pipeline using hot rolled stainless steel according to claim 2, characterized in that The specific grid pattern is an equidistant square pattern, and the spacing between adjacent straight lines is between 0.001-0.2 mm.

9. A low flow resistance and corrosion resistant pipe product made of hot-rolled stainless steel, characterized in that: The tubular product is prepared by the method described in any one of claims 6-8.

10. A low flow resistance and corrosion resistant pipe product as claimed in claim 9, which is used for oil and water transportation.

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