Large-diameter spiral steel pipe forming equipment

Abstract

This invention relates to the technical field of spiral steel pipe processing, and more particularly to a large-diameter spiral steel pipe forming equipment. The equipment includes: laser cleaning to remove oxide scale and oil from the steel strip surface; plasma cutting for trimming and controlling end-face precision; laser-MIG composite welding for head and tail welding; double-wire submerged arc welding for spiral forming; real-time monitoring of weld seam offset via a vision system and automatic adjustment of pinch roller pressure; online full inspection using phased array ultrasonic waves, automatically marking and repairing defects; finished product inspection and pressure testing, including high-pressure water pressure testing and X-ray sampling; and data collection throughout the production process, uploaded to the cloud, and generating a unique traceability code. This invention, through the integrated application of technologies such as laser cleaning, laser-MIG composite welding, visual feedback control, phased array detection, and data traceability, significantly improves the welding quality and production efficiency of spiral steel pipes, achieving intelligent production and quality traceability.

Description

Technical Field

[0001] This invention relates to the technical field of spiral steel pipe processing, and in particular to a large-diameter spiral steel pipe forming equipment. Background Technology

[0002] Spiral welded steel pipe is a type of steel pipe made from strip steel coils, formed by cold extrusion, and welded using an automatic double-wire double-sided submerged arc welding process. Spiral welded pipe generally has higher strength than straight seam welded pipe, and can be produced from narrower blanks to create larger diameter pipes, or from blanks of the same width to produce pipes of different diameters. Therefore, spiral welded steel pipe is widely used in petroleum, natural gas, water conservancy, construction, bridges, and other fields.

[0003] With the rapid development of infrastructure construction in my country, the quality requirements for spiral welded steel pipes are constantly increasing, especially in major projects such as the West-East Gas Pipeline, cross-sea bridges, and urban pipe networks, which place higher demands on the welding quality, dimensional accuracy, and service life of the steel pipes. However, existing spiral welded steel pipe production methods still have the following technical problems: First, in the pretreatment stage of steel strip, traditional methods often use mechanical grinding to remove surface oxide scale and rust. This is not only inefficient but also prone to scratching the steel strip surface. Uneven grinding can lead to localized residual contaminants, which can decompose and generate gas during welding, resulting in welding defects such as porosity and slag inclusions. Meanwhile, the shearing of the steel strip ends often uses mechanical shears, which produces burrs and deformation, making it difficult to guarantee the perpendicularity of the end face and affecting the alignment accuracy of the head and tail welding.

[0004] Secondly, in the welding of the steel strip's beginning and end, traditional processes use manual electric arc welding or single-wire submerged arc welding, which results in slow welding speeds, high heat input, and wide heat-affected zones, making welding deformation prone to occur. Precise control of the welding gap is difficult, often leading to defects such as weld misalignment, incomplete penetration, and weld beads. Especially when burrs, oil stains, or rust are present on the steel strip's end face, the welding quality further deteriorates, causing problems such as misalignment and uneven welding gaps during subsequent spiral forming.

[0005] Third, during the spiral forming process, the steel strip is conveyed by pinch rollers. If the pressure of the pinch rollers is uneven, the steel strip is prone to deviation, which in turn affects the welding gap and the alignment accuracy of the weld. Although existing technologies propose to reduce the pressure difference by adjusting the hydraulic proportional valve, they lack a real-time feedback mechanism, resulting in sluggish adjustment and difficulty in responding to dynamic changes. When the steel strip thickness fluctuates or the edges are uneven, timely adjustments cannot be made, leading to unstable weld quality.

[0006] Fourth, in the weld inspection process, traditional methods mostly rely on manual sampling or offline X-ray inspection, which is inefficient and carries the risk of missed defects. Especially for internal defects such as porosity, slag inclusions, and lack of fusion, conventional ultrasonic testing has limited sensitivity and struggles to detect minute defects. Defect repair is also mostly done manually, resulting in inconsistent repair quality. Furthermore, post-repair inspections are often not conducted, posing potential quality risks.

[0007] Fifth, in the quality management stage, the existing process lacks systematic management of data such as welding parameters and test results, making quality traceability impossible. When quality problems occur, it is difficult to find the cause and to continuously optimize the process.

[0008] Sixth, in the pressure testing phase, traditional hydrostatic tests often employ low-pressure, long-term pressure holding, resulting in low testing efficiency and insensitivity to minor leaks. Improper radial sealing methods can easily lead to seal failure, affecting test accuracy.

[0009] To address the aforementioned issues, there is an urgent need in this field for an intelligent manufacturing and forming method for spiral steel pipes that can improve welding quality, enable real-time monitoring, and support data traceability. Summary of the Invention

[0010] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0011] In view of the problems existing in the above-mentioned large-diameter spiral steel pipe forming equipment, the present invention is proposed.

[0012] Therefore, the purpose of this invention is to provide a large-diameter spiral steel pipe forming equipment, which aims to improve processing quality.

[0013] To solve the above-mentioned technical problems, the present invention provides the following technical solution: S1: raw material pretreatment; S2: Continuous welding of steel strips; S3: Online inspection and repair of weld seams; S4: Finished product inspection and pressure testing; S5: Data traceability.

[0014] As a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, wherein: S11: the surface of the steel strip is treated by a pulsed fiber laser cleaning device with a laser power of 1.5-2.5kW and a scanning speed of 8-12m / min, removing oxide scale, oil stains and rust within 150mm on both sides of the front and back of the steel strip; S12: A seven-roll leveling machine is used to level the steel strip. The flatness of the steel strip is monitored in real time by a laser displacement sensor and controlled to be within 0.5mm / m. S13: The steel strip end is trimmed using a fine plasma cutting device with a cutting current of 100-140A, a cutting voltage of 150-180V, a cutting speed of 1.2-1.8m / min, and the end face perpendicularity error is controlled within ±0.1mm. The surface roughness Ra is ≤3.2μm.

[0015] In a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, step S2 includes: S21: The steel strip is conveyed by five sets of pinch rollers. Each set of pinch rollers is driven independently by a servo motor and equipped with a tension sensor to monitor the steel strip tension in real time and control the tension within the range of 5-8kN. S22: The welding of the steel strip ends adopts the laser-MIG composite welding process. The laser power is 2-4kW, the laser focus is located at the center of the weld, the spot diameter is ≤0.6mm, the welding current is 30-60A, the welding speed is 1.2-1.8m / min, the welding wire diameter is 1.2mm, the wire feeding speed is 5-8m / min, and the butt gap is controlled within the range of 0.01-0.03mm. S23: The spiral forming adopts the double-wire submerged arc welding process, with the front wire welding current of 480-520A, the rear wire welding current of 430-470A, the welding voltage of 30-34V, the welding speed of 1.0-1.4m / min, and the flux layer thickness of 25-35mm. S24: During the welding process, the weld seam offset is monitored in real time by a vision system, which includes a high-resolution industrial camera and an image processing unit. When the weld seam offset exceeds 0.2mm, the control system automatically adjusts the proportional valve in the hydraulic system to adjust the pressure difference of the pinch rollers, so that the steel strip is always in the center of the roller table and the welding gap at the edge of the steel strip is controlled within the range of 0.05-0.15mm. S25: After the steel pipe is formed, the weld surface is repaired by an automatic submerged arc welding machine. The repair welding current is 400-450A, the voltage is 28-32V, the welding speed is 1.2-1.6m / min, and the thickness of the repair weld layer is controlled within the range of 1.5-2.5mm.

[0016] As a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, in step S22, before welding the steel strip head and tail, dirt and rust within 100mm on both sides of the steel strip butt end need to be removed. During the welding process, the weld seam offset is monitored in real time by a visual sensor and the welding gun position is automatically adjusted.

[0017] In a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, step S3 includes: S31: The weld is inspected using an online continuous ultrasonic phased array automatic flaw detector with a detection frequency of 5-10MHz and a detection sensitivity of not less than 10% FBH. The defective areas are automatically marked and the location coordinates and size information of the defects are recorded. S32: Use an automatic argon arc welding machine to locally repair the marked defective areas. The repair current is 90-110A, the voltage is 12-16V, and the wire feeding speed is 3-5m / min. S33: After repair, perform ultrasonic non-destructive testing again to confirm that the defect has been eliminated.

[0018] In a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, step S4 includes: S41: The spiral steel pipe is cut into sections using a plasma cutting machine. The cutting current is 200-250A, the cutting speed is 0.8-1.2m / min, the cutting length is 12m / section, and the perpendicularity error of the cutting end face is ≤2mm. S42: Perform a hydrostatic test on each section of steel pipe. The pressure is applied using a radial seal. The test pressure range is 500-700MPa, and the pressure holding time is ≥10s. The pressure sensor monitors the pressure change in real time. When the pressure drops by more than 5%, an automatic alarm is triggered and the product is marked as unqualified. S43: Conduct X-ray sampling inspections on welds, with a sampling rate of no less than 20%. Use an XXQ-2505 X-ray flaw detector with a tube voltage of 180-220kV and an exposure time of 2-4 minutes.

[0019] In a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, step S5 includes: S51: Automatically collects current, voltage, speed, and temperature parameters during the welding process, as well as defect location, size, and type information in flaw detection, and repair time, parameters, and personnel information in the repair record through the PLC system; S52: The collected data is uploaded to the cloud database in real time via industrial Ethernet, and the data format adopts the JSON standard format; S53: After each steel pipe is produced, the system automatically generates a unique 16-digit traceability code, which includes the production date, production line number, shift, and serial number. The traceability code is printed in the form of a QR code and affixed to the outer surface of the steel pipe.

[0020] As a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, the method further includes step S6: process optimization, in which the cloud database optimizes the welding parameters through big data analysis based on the accumulated production data, and sends the optimized parameters to the production equipment.

[0021] As a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, in step S11, the laser cleaning equipment adopts a pulsed fiber laser with a pulse width of 100-200ns and a repetition frequency of 20-50kHz, which thoroughly removes surface contaminants without damaging the steel strip substrate.

[0022] As a preferred embodiment of the large-diameter spiral steel pipe forming equipment of the present invention, the method is applicable to the production of spiral steel pipes with a diameter of 219-3020mm and a wall thickness of 4-25.4mm.

[0023] The beneficial effects of this invention are as follows: Laser cleaning technology replaces traditional mechanical grinding, thoroughly removing oxide scale and oil stains from the steel strip surface, preventing weld porosity and slag inclusions. Laser-MIG hybrid welding combines the advantages of laser deep penetration welding and MIG welding, resulting in fast welding speed, low heat input, narrow heat-affected zone, and high weld joint strength, reaching over 95% of the base material strength. The steel strip ends are trimmed using plasma cutting, with end face perpendicularity error controlled within ±0.1mm, providing a precise butt joint reference for head and tail welding. The head and tail welding gap is precisely controlled within 0.01-0.03mm, improving accuracy by more than 5 times compared to traditional processes, effectively avoiding misalignment.

[0024] A vision system monitors weld seam offset in real time. When the offset exceeds 0.2mm, the pinch roller pressure is automatically adjusted with a response time of less than 0.5 seconds, ensuring the steel strip remains centered on the roller conveyor. The spiral welding gap remains stable within the range of 0.05-0.15mm, increasing the weld pass rate to over 98.5%. Phased array ultrasonic online full inspection is employed, with a detection sensitivity of 10% FBH, capable of detecting minute defects larger than 0.5mm in diameter, three times more sensitive than traditional ultrasonic testing. Automatic defect marking, repair, and re-inspection form a closed-loop quality control system, achieving a 100% defect elimination rate after repair. Hydrostatic testing pressure reaches 500-700MPa, more than 30% higher than traditional processes, with a holding time ≥10s. Real-time pressure sensor monitoring detects minute leaks, ensuring each steel pipe meets high-pressure requirements. A cloud database collects data from all aspects of the production process, generating a unique traceability code for each steel pipe. Customers can scan the QR code to query the entire lifecycle quality information of the steel pipe. Big data analysis optimizes process parameters, enabling continuous improvement of the production process. Laser cleaning speed is 8-12 m / min, plasma cutting speed is 1.2-1.8 m / min, and welding speed is 1.0-1.8 m / min. The various processes work together, and the overall production efficiency is more than 40% higher than that of traditional processes. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 This is a schematic diagram of the method flow provided by the present invention.

[0026] Figure 2 This is a schematic diagram of the preprocessing flow for step 1 of the present invention.

[0027] Figure 3 This is a schematic diagram of the welding and forming process for step 2 of the present invention.

[0028] Figure 4 This is a schematic diagram of step 3, detection and repair, provided by the present invention.

[0029] Figure 5 This is a schematic diagram of the finished product inspection process for step 4 of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] refer to Figure 1-5 This invention provides a method for forming spiral steel pipes, which includes the following steps: S1: Raw material pretreatment; S2: Continuous welding of steel strips; S3: Online inspection and repair of weld seams; S4: Finished product inspection and pressure testing; S5: Data traceability.

[0032] Step S1 includes: S11: The surface of the steel strip is treated with pulsed fiber laser cleaning equipment. The laser power is 1.5-2.5kW and the scanning speed is 8-12m / min. The oxide scale, oil stains and rust within 150mm on both sides of the steel strip are removed. Preferably, in step S11, the laser cleaning of the steel strip surface uses a pulsed fiber laser cleaning device with a laser power of 2kW, a scanning speed of 10m / min, a pulse width of 150ns, and a repetition frequency of 30kHz. By irradiating the steel strip surface with the laser beam, oxide scale, oil, and rust are instantly vaporized or peeled off, removing contaminants within a 150mm radius on both sides of the steel strip. Laser cleaning can thoroughly remove surface contaminants without damaging the steel strip substrate. After cleaning, the surface cleanliness of the steel strip reaches Sa2.5 level, effectively avoiding surface scratches and uneven grinding caused by traditional mechanical grinding, providing a clean processing surface for subsequent welding.

[0033] S12: A seven-roll leveling machine is used to level the steel strip. The flatness of the steel strip is monitored in real time by a laser displacement sensor and controlled to be within 0.5mm / m. Preferably, in step S12, the steel strip leveling process employs a seven-roll leveling machine. The pressure of the leveling rolls decreases progressively, and the upper and lower rolls are arranged alternately. During leveling, the flatness of the steel strip is monitored in real time using laser displacement sensors. The sensors are installed at the exit of the leveling machine, with three measuring points arranged along the width of the steel strip. When excessive local curvature is detected, the pressure reduction of the leveling rolls is automatically adjusted to ensure that the overall flatness of the steel strip is controlled within 0.5 mm / m. After leveling, the residual stress of the steel strip is reduced by more than 30%, effectively preventing deformation during subsequent welding.

[0034] S13: The steel strip end is trimmed using a fine plasma cutting device with a cutting current of 100-140A, a cutting voltage of 150-180V, a cutting speed of 1.2-1.8m / min, and the end face perpendicularity error is controlled within ±0.1mm. The surface roughness Ra is ≤3.2μm.

[0035] Preferably, in step S13, the plasma cutting trimming of the steel strip end uses a fine plasma cutting device with a cutting current of 120A, a cutting voltage of 160V, and a cutting speed of 1.5m / min. During the cutting process, the plasma arc is always aligned with the center of the steel strip end, and compressed air is used as the cutting gas with a pressure of 0.6MPa and a flow rate of 120L / min. The perpendicularity error of the cut end face is controlled within ±0.1mm, and the surface roughness Ra ≤ 3.2μm. Simultaneously, compressed air is used as the working gas during the cutting process to blow away the cutting slag and prevent slag residue from affecting subsequent welding. After cutting, an industrial camera is used to inspect the steel strip end for burrs, slag, and oxide layers within a 100mm radius on both sides, ensuring that the end face quality meets welding requirements.

[0036] Step S2 includes: S21: The steel strip is conveyed by five sets of pinch rollers. Each set of pinch rollers is driven independently by a servo motor and equipped with a tension sensor to monitor the steel strip tension in real time and control the tension within the range of 5-8kN. Preferably, in step S21, during raw material conveying, the steel strip is conveyed by five sets of pinch rollers. Each set of pinch rollers is independently driven by a servo motor with a power of 5.5kW and a rated speed of 1500rpm. Each set of pinch rollers is equipped with a tension sensor with a range of 0-20kN and an accuracy of ±0.5%. The control system automatically adjusts the speed of each pinch roller based on the tension feedback signal, using a PID control algorithm with a proportional coefficient Kp=0.8, an integral time Ti=0.5s, and a derivative time Td=0.1s. This ensures that the tension of the steel strip remains constant during conveying, controlled within the range of 6kN±0.5kN, avoiding strip misalignment or stacking caused by tension fluctuations.

[0037] S22: The welding of the steel strip ends adopts the laser-MIG composite welding process. The laser power is 2-4kW, the laser focus is located at the center of the weld, the spot diameter is ≤0.6mm, the welding current is 30-60A, the welding speed is 1.2-1.8m / min, the welding wire diameter is 1.2mm, the wire feeding speed is 5-8m / min, and the butt gap is controlled within the range of 0.01-0.03mm. Preferably, in step S22, the welding of the steel strip head and tail is performed using a laser-MIG hybrid welding process. The laser is a YLS-4000 fiber laser with a power of 3kW, a wavelength of 1070nm, and the laser focus is located at the center of the weld with a spot diameter of 0.5mm. The MIG welding machine is a Fronius TPS 4000 model with a welding current of 45A, a welding voltage of 18V, and a welding speed of 1.5m / min. The welding wire is an ER50-6 type with a diameter of 1.2mm and a wire feed speed of 6.5m / min. The shielding gas is 80%Ar + 20%CO2 with a gas flow rate of 20L / min.

[0038] Before welding, the steel strip butt joints are wiped with alcohol within 100mm on both sides to remove dirt and rust. The butt joint gap at the steel strip ends is measured with a feeler gauge and controlled within 0.02mm ± 0.01mm. During welding, the laser beam preheats and forms a keyhole, and the MIG arc fills the gap with welding wire. Weld offset is monitored in real time by a vision sensor, which uses a Basler acA1300-60gm industrial camera with a resolution of 1280×1024, a frame rate of 60fps, and a 12mm focal length lens. The image processing unit uses an NI Vision module to identify the weld position through an edge detection algorithm. When the detected weld offset exceeds 0.2mm, the control system automatically adjusts the welding torch position via a servo motor-driven welding torch movement mechanism, with an adjustment accuracy of ±0.05mm.

[0039] Laser-MIG hybrid welding combines the deep penetration of laser welding with the bridging capability of MIG welding. It increases welding speed by 50% and reduces heat input by 30% compared to traditional MIG welding, controlling the heat-affected zone width to within 1.5mm. The tensile strength of the welded joint reaches 98% of the base material. Strict control of the welding gap within the range of 0.01-0.03mm significantly improves the connection strength during the welding process at the steel strip ends. After removing burrs, stains, and rust, it avoids weld protrusions and surface roughness after welding. It effectively improves the precision of welding the steel strip material at both ends, reducing misalignment after spiral welding.

[0040] S23: The spiral forming adopts the double-wire submerged arc welding process, with the front wire welding current of 480-520A, the rear wire welding current of 430-470A, the welding voltage of 30-34V, the welding speed of 1.0-1.4m / min, and the flux layer thickness of 25-35mm. In the spiral forming process, a dual-wire submerged arc welding process is employed. The welding machine is a Lincoln DC-1000 model, with a front wire welding current of 500A and a rear wire welding current of 450A. The welding voltage is 32V, and the welding speed is 1.2m / min. The welding wire used is H08MnA type, 4.0mm in diameter, and the flux used is SJ101 type, with a flux layer thickness of 30mm. The steel strip is continuously spirally butt-jointed through a forming machine, with a forming angle of 45°-55° to form a steel pipe. During the welding process, a laser rangefinder monitors the outer diameter of the steel pipe. The rangefinder has a range of 0-3m and an accuracy of ±0.5mm. When the outer diameter deviation exceeds ±2mm, the forming roller position is automatically adjusted.

[0041] S24: During the welding process, the weld seam offset is monitored in real time by a vision system, which includes a high-resolution industrial camera and an image processing unit. When the weld seam offset exceeds 0.2mm, the control system automatically adjusts the proportional valve in the hydraulic system to adjust the pressure difference of the pinch rollers, so that the steel strip is always in the center of the roller table and the welding gap at the edge of the steel strip is controlled within the range of 0.05-0.15mm. In step S24, error coordination, the gap at the edge of the steel strip must be within the range of 0.05-0.15mm, and this is checked periodically using a feeler gauge. The pinch rollers continuously transport the long steel strip until it is successively spirally welded. A vision system, including a high-resolution industrial camera and an image processing unit, monitors the weld seam offset in real time to identify the weld seam edge position. The camera is mounted 300mm in front of the welding point to capture images of the steel strip edge, and an image processing algorithm calculates the deviation between the weld seam centerline and the theoretical position.

[0042] When a weld seam offset exceeding 0.2mm is detected, the control system automatically adjusts the proportional valve in the hydraulic system. The proportional valve is a Rexroth 4WRPEH10 with a response time of <20ms. By adjusting the opening of the proportional valve, the pressure of the pinch roller cylinders is changed, reducing the pressure difference between the pinch rollers to within ±5%. The steel strip experiences uniform force during transmission, ensuring the steel plate remains centered on the roller conveyor, allowing for smooth edge joining and maintaining the joining gap. This effectively avoids deviations in the steel strip edge joining caused by strip displacement, ensuring the accuracy of the welding gap and the welding strength during spiral welding. Actual measurements show that after adopting this system, the standard deviation of weld seam offset decreased from 0.35mm to 0.12mm, and the weld gap qualification rate increased from 85% to 97%.

[0043] S25: After the steel pipe is formed, the weld surface is repaired by an automatic submerged arc welding machine. The repair welding current is 400-450A, the voltage is 28-32V, the welding speed is 1.2-1.6m / min, and the thickness of the repair weld layer is controlled within the range of 1.5-2.5mm.

[0044] In step S25, automatic welding repair, after the steel pipe is formed, an automatic submerged arc welding machine is used to repair the weld surface. The welding current is 420A, the voltage is 30V, and the welding speed is 1.4m / min. The welding machine adopts a gantry-type traveling mechanism, moving along the weld direction. The thickness of the repair layer is controlled within the range of 2.0mm ± 0.3mm to ensure that the weld reinforcement height meets the requirements of GB / T 9711 standard. After the repair welding, a laser contour sensor is used to detect the weld reinforcement height, which is controlled within the range of 1.5-3.0mm. If the height exceeds the tolerance, an automatic alarm is triggered, and the repair welding is repeated.

[0045] In step S22, before welding the steel strip head and tail, dirt and rust within 100mm on both sides of the steel strip butt joint must be removed. During the welding process, the weld seam offset is monitored in real time by a visual sensor and the welding gun position is automatically adjusted.

[0046] Step S3 includes: S31: The weld is inspected using an online continuous ultrasonic phased array automatic flaw detector with a detection frequency of 5-10MHz and a detection sensitivity of not less than 10% FBH. The defective areas are automatically marked and the location coordinates and size information of the defects are recorded. All welded seams underwent online continuous ultrasonic phased array automatic flaw detector inspection. The flaw detector was an Olympus OmniScan MX2 model, equipped with a 5MHz linear phased array probe with 32 probe elements and an element spacing of 0.6mm. The detection sensitivity was set to 10% FBH (1.2mm diameter flat-bottomed hole), the scanning angle was -15° to +15°, and the focusing depth was the center of the wall thickness. The phased array probe performed a spiral scan along the weld seam with a scanning pitch of 2mm, enabling simultaneous detection of defects such as porosity, slag inclusions, lack of fusion, and cracks within the weld seam. Defect locations were automatically marked with high-temperature paint, with a spray diameter of 20mm, and the defect location coordinates and dimensions were recorded and stored in the PLC system.

[0047] S32: Use an automatic argon arc welding machine to locally repair the marked defective areas. The repair current is 90-110A, the voltage is 12-16V, and the wire feeding speed is 3-5m / min. Specifically, the marked defects were locally repaired using an automatic TIG welding machine (OTC AVP-300 model), with a repair current of 100A, voltage of 14V, and wire feed speed of 4m / min. The welding wire used was TG50 type, 1.2mm in diameter, and the shielding gas was pure argon with a flow rate of 12L / min. Before repair, the defective areas were ground with an angle grinder to remove defective metal. The grinding depth was 0.5mm deeper than the defect depth, and the grinding width was 5mm wider than the defect width. After repair, the weld reinforcement was controlled within 1.5mm, with uniform width.

[0048] S33: After repair, perform ultrasonic non-destructive testing again to confirm that the defect has been eliminated.

[0049] In the re-inspection and confirmation process, the repaired weld seam is inspected again using an ultrasonic phased array flaw detector, employing the same testing parameters as in S31. If defects still exist, steps S32-S33 are repeated until the defects are confirmed to be eliminated. The re-inspection pass rate is required to be 100%, ensuring that every steel pipe weld seam is defect-free.

[0050] Step S4 includes: S41: The spiral steel pipe is cut into sections using a plasma cutting machine. The cutting current is 200-250A, the cutting speed is 0.8-1.2m / min, the cutting length is 12m / section, and the perpendicularity error of the cutting end face is ≤2mm. Preferred method: The spiral steel pipe is cut into sections using a Hypertherm HPR400XD plasma cutting machine with a cutting current of 230A, a cutting voltage of 200V, a cutting speed of 1.0m / min, and a cutting length of 12m / segment. The perpendicularity error of the cut end face is ≤2mm. Underwater cutting is used to reduce the heat-affected zone and cutting fumes. After cutting, the cut end face is machined using an end milling machine, with an end face roughness Ra≤12.5μm and an end face perpendicularity ≤1mm, in preparation for subsequent pipe end beveling.

[0051] S42: Perform a hydrostatic test on each section of steel pipe. The pressure is applied using a radial seal. The test pressure range is 500-700MPa, and the pressure holding time is ≥10s. The pressure sensor monitors the pressure change in real time. When the pressure drops by more than 5%, an automatic alarm is triggered and the product is marked as unqualified. Preferred method: During the hydrostatic test, each steel pipe undergoes a hydrostatic pressure test using a Dalian Kraf WS-2000 hydrostatic testing machine. Radial sealing is employed, with the sealing ring made of polyurethane material with a hardness of 90 Shore A. The test pressure is set at 600 MPa, and the holding time is 15 seconds. During the test, a pressure sensor monitors pressure changes in real time at a sampling frequency of 100 Hz. An automatic alarm is triggered and the pipe is marked as defective when the pressure drops by more than 5% (i.e., below 570 MPa). Rust-preventive water with a pH of 8.5-9.5 and a conductivity <500 μS / cm is used for the test. After the test, compressed air is used to dry the inside of the pipe to prevent corrosion.

[0052] S43: Conduct X-ray sampling inspections on welds, with a sampling rate of no less than 20%. Use an XXQ-2505 X-ray flaw detector with a tube voltage of 180-220kV and an exposure time of 2-4 minutes.

[0053] In the X-ray inspection, weld seams were sampled at a rate of 20%. The X-ray flaw detector was a XXQ-2505 model, with a tube voltage of 200kV, a tube current of 5mA, and an exposure time of 3 minutes. Agfa D7 film was used, with lead foil intensifying screens (0.03mm front screen, 0.1mm rear screen). The radiographic quality was no lower than grade AB, with film density of 1.8-3.0. The evaluation standard followed NB / T47013.2-2015, with Grade II being acceptable. If defects were found during the sampling inspection, the sampling rate for that batch of steel pipes was doubled; if defects still existed, the entire batch was inspected.

[0054] Step S5 includes: S51: Automatically collects current, voltage, speed, and temperature parameters during the welding process, as well as defect location, size, and type information in flaw detection, and repair time, parameters, and personnel information in the repair record through the PLC system; Ideally, during data acquisition, parameters such as current, voltage, speed, and temperature during the welding process are collected by the welding power source and sensors, and transmitted to the PLC via a Profibus-DP bus. In flaw detection, information such as defect location, size, and type is transmitted from the phased array flaw detector to the industrial computer via Ethernet. Repair records, including repair time, parameters, and personnel, are entered by the operator through the HMI interface. All data uses a unified timestamp and a sampling frequency of 1Hz to ensure data synchronization.

[0055] S52: The collected data is uploaded to the cloud database in real time via industrial Ethernet, and the data format adopts the JSON standard format; A better approach: During data upload, the collected data is uploaded to the cloud database in real time via industrial Ethernet, using the MQTT protocol and the JSON standard format. Data fields include: steel pipe ID, production time, steel strip batch number, welding current, welding voltage, welding speed, laser power, tension value, defect location, defect type, repair parameters, operator, etc. The upload frequency is once per minute; in case of network interruption, the data is cached locally and resumed later.

[0056] S53: After each steel pipe is produced, the system automatically generates a unique 16-digit traceability code, which includes the production date, production line number, shift, and serial number. The traceability code is printed in the form of a QR code and affixed to the outer surface of the steel pipe.

[0057] The method also includes step S6: process optimization, in which the cloud database optimizes welding parameters through big data analysis based on accumulated production data, and sends the optimized parameters to the production equipment.

[0058] In step S11, the laser cleaning equipment uses a pulsed fiber laser with a pulse width of 100-200ns and a repetition frequency of 20-50kHz to thoroughly remove surface contaminants without damaging the steel strip substrate.

[0059] The method is applicable to the production of spiral steel pipes with a diameter of 219-3020 mm and a wall thickness of 4-25.4 mm.

[0060] The large-diameter spiral steel pipe forming equipment proposed in this invention has been described in detail above, and the principles and implementation methods of this invention have been explained. The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A large-diameter spiral steel pipe forming equipment, characterized in that: Includes the following steps: S1: Raw material pretreatment; S2: Continuous welding of steel strips; S3: Online inspection and repair of weld seams; S4: Finished product inspection and pressure testing; S5: Data traceability.

2. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: Step S1 includes: S11: The surface of the steel strip is treated with pulsed fiber laser cleaning equipment. The laser power is 1.5-2.5kW and the scanning speed is 8-12m / min. The oxide scale, oil stains and rust within 150mm on both sides of the steel strip are removed. S12: A seven-roll leveling machine is used to level the steel strip. The flatness of the steel strip is monitored in real time by a laser displacement sensor and controlled to be within 0.5mm / m. S13: The steel strip end is trimmed using a fine plasma cutting device with a cutting current of 100-140A, a cutting voltage of 150-180V, a cutting speed of 1.2-1.8m / min, and the end face perpendicularity error is controlled within ±0.1mm. The surface roughness Ra is ≤3.2μm.

3. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: Step S2 includes: S21: The steel strip is conveyed by five sets of pinch rollers. Each set of pinch rollers is driven independently by a servo motor and equipped with a tension sensor to monitor the steel strip tension in real time and control the tension within the range of 5-8kN. S22: The welding of the steel strip ends adopts the laser-MIG composite welding process. The laser power is 2-4kW, the laser focus is located at the center of the weld, the spot diameter is ≤0.6mm, the welding current is 30-60A, the welding speed is 1.2-1.8m / min, the welding wire diameter is 1.2mm, the wire feeding speed is 5-8m / min, and the butt gap is controlled within the range of 0.01-0.03mm. S23: The spiral forming adopts the double-wire submerged arc welding process, with the front wire welding current of 480-520A, the rear wire welding current of 430-470A, the welding voltage of 30-34V, the welding speed of 1.0-1.4m / min, and the flux layer thickness of 25-35mm. S24: During the welding process, the weld seam offset is monitored in real time by a vision system, which includes a high-resolution industrial camera and an image processing unit. When the weld seam offset exceeds 0.2mm, the control system automatically adjusts the proportional valve in the hydraulic system to adjust the pressure difference of the pinch rollers, so that the steel strip is always in the center of the roller table and the welding gap at the edge of the steel strip is controlled within the range of 0.05-0.15mm. S25: After the steel pipe is formed, the weld surface is repaired by an automatic submerged arc welding machine. The repair welding current is 400-450A, the voltage is 28-32V, the welding speed is 1.2-1.6m / min, and the thickness of the repair weld layer is controlled within the range of 1.5-2.5mm.

4. The large-diameter spiral steel pipe forming equipment according to claim 3, characterized in that: In step S22, before welding the steel strip head and tail, dirt and rust within 100mm on both sides of the steel strip butt joint must be removed. During the welding process, the weld seam offset is monitored in real time by a visual sensor and the welding gun position is automatically adjusted.

5. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: Step S3 includes: S31: The weld is inspected using an online continuous ultrasonic phased array automatic flaw detector with a detection frequency of 5-10MHz and a detection sensitivity of not less than 10% FBH. The defective areas are automatically marked and the location coordinates and size information of the defects are recorded. S32: Use an automatic argon arc welding machine to locally repair the marked defective areas. The repair current is 90-110A, the voltage is 12-16V, and the wire feeding speed is 3-5m / min. S33: After repair, perform ultrasonic non-destructive testing again to confirm that the defect has been eliminated.

6. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: Step S4 includes: S41: The spiral steel pipe is cut into sections using a plasma cutting machine. The cutting current is 200-250A, the cutting speed is 0.8-1.2m / min, the cutting length is 12m / section, and the perpendicularity error of the cutting end face is ≤2mm. S42: Perform a hydrostatic test on each section of steel pipe. The pressure is applied using a radial seal. The test pressure range is 500-700MPa, and the pressure holding time is ≥10s. The pressure sensor monitors the pressure change in real time. When the pressure drops by more than 5%, an automatic alarm is triggered and the product is marked as unqualified. S43: Conduct X-ray sampling inspections on welds, with a sampling rate of no less than 20%. Use an XXQ-2505 X-ray flaw detector with a tube voltage of 180-220kV and an exposure time of 2-4 minutes.

7. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: Step S5 includes: S51: Automatically collects current, voltage, speed, and temperature parameters during the welding process, as well as defect location, size, and type information in flaw detection, and repair time, parameters, and personnel information in the repair record through the PLC system; S52: The collected data is uploaded to the cloud database in real time via industrial Ethernet, and the data format adopts the JSON standard format; S53: After each steel pipe is produced, the system automatically generates a unique 16-digit traceability code, which includes the production date, production line number, shift, and serial number. The traceability code is printed in the form of a QR code and affixed to the outer surface of the steel pipe.

8. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: The method also includes step S6: process optimization, in which the cloud database optimizes welding parameters through big data analysis based on accumulated production data, and sends the optimized parameters to the production equipment.

9. The large-diameter spiral steel pipe forming equipment according to claim 2, characterized in that: In step S11, the laser cleaning equipment uses a pulsed fiber laser with a pulse width of 100-200ns and a repetition frequency of 20-50kHz to thoroughly remove surface contaminants without damaging the steel strip substrate.

10. The large-diameter spiral steel pipe forming equipment according to claim 1, characterized in that: The method is applicable to the production of spiral steel pipes with a diameter of 219-3020 mm and a wall thickness of 4-25.4 mm.

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