Manufacturing method for automobile high-strength steel part shaped like Chinese character'ri 'based on laser rolling forming

Abstract

The invention discloses a manufacturing method of an automobile high-strength steel part shaped like a Chinese character'ri 'based on laser rolling forming. The manufacturing method comprises the following steps that preparation work is completed; bending and forming the plate by using a robot; for the horizontally-arranged plate, the second end is sequentially bent vertically upwards, horizontally inwards and vertically downwards, so that the second end makes contact with the upper surface of the non-bent plate, and a closed rectangular pipe is formed; the first end is vertically and upwards bent and horizontally and inwards bent in sequence to form a C-shaped pipe, the first end makes contact with the outer surface of the bent position of the closed rectangular pipe, and closing is formed; laser filling wire fusion welding is carried out on the two connectors, and a closed pipe shaped like a Chinese character'ri 'is formed; and carrying out aerial fog shaping, cooling and straightening after welding. According to the manufacturing method, high-precision and low-resilience manufacturing of bumpers made of high-strength steel, ultrahigh-strength steel and light-weight materials can be achieved, the precision, strength and light-weight level of products can be improved, and meanwhile the industrial common problems that in a traditional technology, the number of passes is large, resilience is large, and energy consumption is high are solved.

Description

Technical Field

[0001] This specification relates to the field of advanced manufacturing technology for automotive parts, and in particular to a method for manufacturing high-strength steel automotive parts with a H-shape based on laser roll forming. Background Technology

[0002] As a core component of a vehicle's passive safety system, the car bumper not only undertakes crucial functions such as collision energy absorption and pedestrian protection, but also directly affects the vehicle's aerodynamic performance and lightweighting effectiveness. With increasingly stringent global energy conservation and emission reduction regulations (such as China's "dual carbon" target and the European EU2023 / 851 standard), lightweight bumper design has become an inevitable trend in the automotive industry. Currently, mainstream bumper materials are shifting from traditional low-carbon steel to high-strength steel (such as DP980 and 22MnB5), aluminum alloys (such as 6061 and 6082), and composite materials. However, these materials are prone to defects such as springback, thinning, and edge cracking during the forming process, placing extremely high demands on manufacturing processes. Therefore, developing efficient, precise, and flexible bumper forming methods is urgently needed. Currently, the forming processes for car bumpers mainly include traditional methods such as cold bending / continuous roll forming, hot stamping (PHS), hydroforming, and multi-sheet welding.

[0003] Cold bending / continuous roll forming is the mainstream solution for traditional bumper manufacturing. It involves shaping the sheet metal into a predetermined cross-section through multiple roll forming or die bending, followed by sealing using methods such as high-frequency welding or argon arc welding. The principle is to gradually accumulate the plastic deformation of the metal to achieve cross-section shaping. However, it has the following significant drawbacks when using AHSS / UHSS (Advanced High Strength Steel / Ultra-High Strength Steel): 1. High springback: AHSS has high yield strength (≥1500MPa) and obvious elastic recovery after cold bending. The springback angle after a 90° bend can reach 2°-5°. It requires an additional 3-5 shaping processes, which leads to an extended production cycle (single piece forming time 8-12 minutes). 2. Poor corner quality: To avoid edge cracking, the cold bending process needs to control the corner radius to plate thickness ratio (R / t) ≥ 5, resulting in low cross-sectional utilization. Compared with a small R / t cross-section (R / t=2-3), the weight reduction potential is reduced by 8%-12%. At the same time, the corner thinning rate is likely to exceed 15%, which can easily cause stress concentration during a collision, leading to premature failure of the bumper. 3. High changeover cost: Continuous roll forming requires a dedicated roller system for different car models (each roller system costs 50,000-100,000 RMB). When changing models, the roller system needs to be disassembled, installed and calibrated, which takes 2-3 days. It cannot be adapted to small-batch customized car models with an annual production of 1,000-5,000 pieces. 4. Poor weld stability: When traditional argon arc welding is used for AHSS, a martensitic embrittlement layer with a thickness of 0.3-0.5mm is easily generated in the heat-affected zone (HAZ), resulting in a 20%-30% decrease in weld toughness and a pass rate of only 85%-90%.

[0004] Hot stamping, by heating sheet metal to its austenitizing temperature (900-950℃), rapidly pressing and quenching it in a mold, can produce high-strength components with tensile strengths of 1500-2000MPa. These components are widely used in safety parts such as B-pillars and door sills in car bodies. However, their application in bumper manufacturing has the following limitations: 1. High energy consumption and cost: Heating the entire plate requires a large amount of energy, with each ton of AHSS component consuming 800-1200 kWh, which is 3-4 times that of the cold bending process; at the same time, the plate needs to be coated with an Al-Si coating (costing 15%-20% of the total component cost) to prevent oxidation, and subsequent shot blasting is required to remove coating residue, increasing additional process costs; 2. Long mold cycle: Hot stamping molds require the use of high-temperature resistant mold steel (such as H13) and the design of cooling water channels. The development cycle is 3-6 months, and the cost of each mold is 200,000-500,000 yuan. It is not suitable for the rapid iteration of bumper design. 3. Low forming flexibility: Hot stamping is suitable for complex but fixed cross-sections, but it cannot achieve rapid adjustment of the cross-section of the H-shaped tube, and the mold wears out quickly (lifespan of about 50,000 pieces), resulting in high maintenance costs in the later stage; 4. Poor surface quality: Oxide scale (5-10μm thick) is easily generated on the surface of the sheet during the heating process. Even after shot blasting, the surface roughness still reaches Ra=3.2-6.3μm, requiring an additional spraying process to meet the appearance requirements.

[0005] Hydraulic forming uses high-pressure liquid (30-100MPa) to press a tube or plate blank into a mold cavity, resulting in a hollow cross-section with few or no welds. It is suitable for complex curved surface components, but it has the following problems when used for H-shaped tube bumpers: 1. High equipment investment: High-pressure water expansion equipment requires booster pumps, sealing devices and control systems, with the cost of a single unit ranging from 1 million to 3 million yuan, far exceeding the investment budget of small and medium-sized car companies; 2. Long forming cycle: A single forming process requires "filling liquid-pressurizing-holding pressure-depressurizing", which takes 3-5 minutes per piece, and the production efficiency is only 1 / 2 of that of the cold bending process; 3. Narrow material adaptability: Hydraulic forming requires high material elongation (≥15%), while UHSS elongation is usually ≤10%, which easily leads to cracking during the forming process, resulting in a scrap rate of 10%-15%; 4. Low cross-sectional accuracy: The forming of the middle reinforcing rib of the H-shaped tube depends on the precise control of the mold cavity. However, the mold is prone to elastic deformation under high pressure, resulting in a dimensional tolerance of ±0.5mm for the reinforcing rib, which affects subsequent assembly.

[0006] Regarding the forming of the H-shaped bumper, although the two existing core patented technologies (CN110576292B and CN110038963B) have improved upon traditional processes, they have not yet overcome the aforementioned technical bottlenecks. The specific limitations are analyzed as follows: (1) Patent CN110576292B (A method for manufacturing an automobile bumper) This patent discloses a method for manufacturing H-shaped tubes using a process of "rectangular tube + C-shaped profile welding → electromagnetic induction heating → hot roll bending + online quenching." The process route is as follows: manufacturing a rectangular tube → bending both ends of the sheet metal at 90° → forming a C-shaped profile → welding the C-shaped profile to the rectangular tube to form a H-shaped tube → electromagnetic induction heating → hot roll bending forming + online quenching. The core issue is: 1. The heating system is complex and energy-intensive: It requires a rectangular outer induction coil and an inner induction coil with a magnetic conductor. The gap between the coils must be strictly controlled (the gaps on the left and right sides and the top and bottom sides are both 10mm). The tooling debugging time is as long as 2-4 hours per set. At the same time, electromagnetic induction heating needs to heat the entire H-shaped tube (rather than the local deformation area). The energy consumption per ton of component is 1500-2000kWh, which is 3-4 times that of the laser heating of this invention. 2. Limited accuracy of hot roller bending: Bending is achieved by moving the roller along the outer wall of the tube. There is insufficient control over the springback of high-strength steel. The springback angle of complex curvature parts (such as arc segments with a radius ≤500mm) can reach 1.5°-3°, requiring additional straightening processes. 3. Poor weldability: When using laser or argon arc welding to butt the two ends of the C-shaped profile with the rectangular tube, the thickness difference of the sheet metal must be ≤0.3mm. Otherwise, the weld strength will fluctuate by ±15%. However, in actual production, the sheet metal thickness deviation often reaches 0.5mm, resulting in a pass rate of only 88%-92%. 4. Difficult to change the form: Rectangular tube manufacturing requires special roller pressing molds, and C-shaped profile forming requires special bending molds. When changing the form, two sets of molds need to be replaced and recalibrated, which takes 1-2 days and cannot meet the needs of multiple varieties.

[0007] (2) Patent CN110038963B (Forming method and forming mold for H-shaped tubes) This patent discloses a "multi-step bending + multi-welding" method for forming H-shaped tubes. The process route is as follows: bend the two ends of the sheet metal in opposite directions at 90° → fold vertically upwards, horizontally, and vertically downwards in sequence → weld → bend again → weld again → disassemble the mold. Its core drawback is: 1. Long forming cycle: It needs to go through 5 - 6 steps of bending and 2 times of welding. The forming time for each piece reaches 8 - 12 minutes, and the production efficiency is only 60% - 70% of the traditional cold bending process; 2. Complicated die adjustment: Wedge-shaped die adjustment blocks and bolts are used to control the die height. The adjustment accuracy is only ±0.1 mm, resulting in a cross-sectional dimension tolerance of the day-shaped tube reaching ±0.3 mm, which cannot meet the assembly accuracy requirements of the bumper and the body (the assembly tolerance needs to be ≤±0.2 mm); 3. High risk of welding quality: Two times of welding lead to the superposition of HAZ (the thickness of the superposition area reaches 0.5 - 0.8 mm). Micro-cracks are likely to occur in AHSS (the incidence rate is 5% - 8%), and there are many weld seams (2 main weld seams), increasing the leakage risk; 4. Difficult die removal: After forming, the bolts need to be rotated to lower the die adjustment block to disengage from the workpiece. If the die fits too tightly with the workpiece (such as due to thermal expansion and contraction), it is easy to cause workpiece deformation or die jamming, and the scrap rate reaches 5% - 7%. Summary of the Invention

[0008] In view of the deficiencies of the prior art, an object of this specification is to provide a manufacturing method for day-shaped automotive high-strength steel parts based on laser roll forming, which can achieve high-precision and low springback manufacturing of bumpers made of high-strength steel, ultra-high-strength steel and lightweight materials, significantly improve the product precision, strength and lightweight level, and at the same time overcome the common industry problems in the traditional process such as many passes, large springback and high energy consumption.

[0009] To achieve the above object, an embodiment of this specification provides a manufacturing method for day-shaped automotive high-strength steel parts based on laser roll forming, including the following steps: Step S10: Complete the preparatory work; the preparatory work includes sheet metal and surface preparation, power-on self-check, tooling and zero position calibration, and robot TCP calibration; the robot is connected with a roll head and a laser head; the sheet metal has opposite first and second ends; Step S20: Use the robot to bend and form the sheet metal; during the bending and forming process, the laser head irradiates the outer surface of the area to be bent, and a rectangular light spot or a swinging light spot is used to cover the deformation area. The laser head and the roll head maintain a predetermined distance, and the bending angle for each pass is less than or equal to 8°; for the horizontally arranged sheet metal, first, the second end is successively bent vertically upward, horizontally inward and vertically downward so that the second end contacts the upper surface of the unbent sheet metal to form a closed rectangular tube; then, the first end is successively bent vertically upward and horizontally inward to form a C-shaped tube so that the first end contacts the outer surface of the bending part of the closed rectangular tube to form a closure; Step S3: Laser wire filling fusion welding is carried out on the two interfaces to form a closed day-shaped tube; Step S40: Post-weld aerosol shaping, cooling and straightening; including aerosol shaping, straightening, online detection and feedback optimization; the aerosol shaping cooling includes shaping cooling by covering the weld toe and bending area with aerosol, the spray coverage area being 1.5 to 5 times the heat-affected zone of the laser molten pool at the weld toe; the equivalent cooling rate is 50℃ / s to 200℃ / s, the thickness-to-temperature difference is controlled to be less than or equal to 40℃ to 60℃, and if the temperature difference exceeds the limit, the linear speed is automatically reduced and the spray flow rate is increased.

[0010] In a preferred embodiment, step S10, the sheet metal and surface preparation includes: The plate material is selected from high-strength steel, with a yield strength greater than or equal to 1500MPa, a tensile strength of 1600mPa~1800mPa, and an elongation greater than or equal to 8%; the thickness of the plate material is 1mm~5mm, and the thickness deviation is less than or equal to ±0.05mm. The surface preparation includes leveling: the sheet material is leveled using a two-roll or four-roll leveler, and the leveling pressure is set to 5-8 MPa according to the sheet material thickness to ensure that the flatness of the sheet material is less than or equal to 0.2 mm / m and the surface roughness of the rollers is less than or equal to 0.8 μm; The surface preparation includes cleaning and drying: removing oil, scale, and other impurities from the board surface using a spray cleaning machine, employing an alkaline cleaning agent with a concentration of 5% to 8%, at a cleaning temperature of 40℃ to 60℃ for 2 to 3 minutes; subsequently drying in a hot air drying oven at 80℃ to 120℃ for 1 to 2 minutes, ensuring that the surface moisture content of the board is less than or equal to 0.1%; The surface preparation includes burr detection: a laser thickness gauge is used to detect burrs on the edge of the sheet metal with a detection accuracy of ±0.001mm, ensuring that the burr height is less than or equal to 0.1mm; if the burrs exceed the standard, a grinding machine with a grit size of 120~180 mesh is used for trimming, and the edge roughness after trimming is less than or equal to 1.6μm.

[0011] In a preferred embodiment, the power-on self-test in step S10 includes: main control and servo system testing, laser head testing, spray system testing, sensor calibration, and alarm system testing; The main control and servo system detection includes: starting the main control PLC, establishing communication with the robot's servo system, and detecting a communication delay of less than or equal to 10ms; checking the servo motor current and speed through the PLC diagnostic interface to ensure that the current fluctuation is ≤±5% and the speed deviation is ≤±1rpm. The laser head testing includes: starting the fiber laser, performing a power stability test, setting the power to 1000W~5000W, with an interval of 1000W, maintaining each power point for 5 minutes, and detecting power fluctuations ≤±2%; at the same time, checking the coaxiality of the laser optical path, using a laser collimator to ensure that the optical path deviation is ≤0.05mm / m; The spray system testing includes: activating the aerosol cooling system and checking the flow rate of each nozzle, with the flow rate set to 5-15 L / h; adjusting the flow rate according to the sheet thickness: 5-10 L / h for 1-2 mm thick sheets and 10-15 L / h for 3-5 mm thick sheets; the flow rate error should be ≤ ±5%; simultaneously checking the spray uniformity using filter paper testing, with the spray coverage area deviation ≤ ±10%. The sensor calibration includes: temperature accuracy calibration of the temperature measuring camera using a standard blackbody furnace with a temperature range of 500-1000℃ and a calibration accuracy of ±2℃; range calibration of the force sensor with a range of 0-50kN and an accuracy of ±0.1%; and linearity calibration of the displacement sensor with a linearity of ±0.005mm. The alarm system test includes: simulating equipment malfunction, checking whether the audible and visual alarm system is triggered normally, and the alarm response time is ≤100ms.

[0012] In a preferred embodiment, in step S10, the tooling and zero-position calibration includes: standard alignment block preparation, rolling head zero-position calibration, roll gap calibration, centering calibration, and reference code storage; The preparation of the standard alignment block includes: selecting a standard alignment block made of 45 steel with a hardness of HRC28-32, whose size is consistent with the cross-section of the tube to be formed, with a dimensional accuracy of ±0.005mm and a surface roughness Ra≤0.8μm; the standard alignment block is set with 3 reference points for laser positioning. The zero-position calibration of the rolling head includes: fixing the standard alignment block on the worktable, using a robot to drive a rolling head made of WC-Co material with a hardness of HRC60-65 to fit against the surface of the standard alignment block, recording the coordinates of the rolling head in the X, Y, and Z directions, and setting them as the zero position; repeating the calibration 3 times to ensure a repeatability accuracy of ±0.01mm; the diameter of the rolling head roller is set to 50-100mm according to the thickness of the sheet material; the diameter of the rolling head roller is 50-60mm for 1-2mm thick sheet material, and 80-100mm for 3-5mm thick sheet material; the width of the rolling head roller is 2-3mm larger than the width of the sheet material. The roll gap calibration includes: setting the roll gap according to the sheet thickness, with the roll gap value being 0.05~0.1mm larger than the sheet thickness; and checking the roll gap using a feeler gauge with an accuracy of ±0.001mm to ensure that the roll gap deviation is ≤±0.01mm. The alignment calibration includes: using a laser alignment instrument to detect the alignment between the sheet material conveying path and the rolling head; adjusting the position of the worktable so that the deviation between the center of the sheet material and the center of the rolling head is ≤0.05mm; after alignment, recording the worktable coordinates as a reference for subsequent forming. The reference code storage includes: storing reference data such as zero coordinates, roll gap parameters, and centering coordinates into the encrypted storage unit of the PLC; and simultaneously generating a calibration report, recording the calibration time, operator, and equipment status. In step S10, the robot TCP calibration includes: laser focus calibration, nozzle coaxiality calibration, and TCP repeatability accuracy test; The laser focus calibration includes: using a laser focus test card, adjusting the robot's posture so that the laser focus falls on the center of the test card, and recording the focus coordinates; and adjusting the position of the focusing lens with a focal length of 150-200mm to ensure that the focus diameter deviation is ≤±0.1mm. The nozzle coaxiality calibration includes: installing a brass nozzle with an inner diameter of 2-5mm at the end of the laser head, and using a coaxiality tester to check the coaxiality between the nozzle center and the laser focus to ensure that the coaxiality is ≤0.05mm; if the coaxiality exceeds the standard, adjust the nozzle fixing bolts until the requirements are met. The TCP repeatability accuracy test includes: the robot moves the laser head and the rolling head to 5 different positions in the workspace, stops at each position and records the TCP coordinates, calculates the repeatability accuracy, and ensures the repeatability accuracy is ±0.02mm; the calibration frequency is set to once every 8 hours, and if the equipment is shut down for more than 2 hours, recalibration is performed.

[0013] In a preferred embodiment, in step S20, before using the robot to bend and shape the sheet, preset process parameters are loaded according to the sheet material and cross-sectional dimensions. The process parameters include laser parameters, rolling parameters, and temperature control parameters. The laser parameters include laser power, spot type, linear velocity, and predetermined distance; the laser power is 1500W-2500W; the spot type is a rectangular spot or a wobbling spot with a size of 2mm×5mm, the wobbling amplitude of the wobbling spot is 1-3mm, and the frequency is 50-200Hz; the linear velocity is 300-800mm / min; and the predetermined distance between the laser head and the rolling head is 5-15mm. The rolling parameters include the number of passes, rolling pressure, and rolling speed; the number of passes is determined based on the total bending angle and the maximum bending angle per pass; the rolling pressure is 8-15kN; the rolling speed is synchronized with the laser linear speed and is 300-800mm / min. The temperature control parameters include a target temperature window, a temperature fluctuation threshold, and a compensation strategy. The target temperature window is 600-800℃; the temperature fluctuation threshold is ±10℃ or ±15℃; and the compensation strategy includes: when the temperature is below the target lower limit, increasing the laser power by 5%-10% or decreasing the line speed by 10%-20%; and when the temperature is above the target upper limit, decreasing the laser power by 5%-10% or increasing the line speed by 10%-20%.

[0014] In a preferred embodiment, step S20, before using the robot to bend and shape the sheet metal, further includes: The sheet material is transported during the positioning and fixing of the sheet material; the pre-processed sheet material is transported to the worktable by a servo feeder with an accuracy of ±0.05mm, and the feeding length is set according to the unfolded length of the H-shaped tube; Positioning and clamping of sheet metal is performed; pneumatic grippers with a clamping force of 5-10kN are used to fix the sheet metal on the worktable, and rubber pads with a thickness of 2mm and a hardness of Shore A60 are attached to the contact parts between the grippers and the sheet metal; the positioning reference is two adjacent edges of the sheet metal, and the position deviation of the sheet metal is ensured to be ≤±0.05mm by positioning pins with an accuracy of ±0.005mm. Visual positioning confirmation is performed during sheet material positioning and fixing; the industrial camera is activated to capture the sheet material positioning status, which is compared with the preset positioning template to calculate the position deviation. If the deviation exceeds ±0.05mm, the position of the servo feeder is automatically adjusted until the requirements are met.

[0015] In a preferred embodiment, in step S20, the bending and forming of the sheet metal using the robot includes a first bending segment, a second bending segment, a third bending segment, a fourth bending segment, and a fifth bending segment. The first bending section is a vertically upward bending section in the closed rectangular tube forming stage; the robot drives the laser head to irradiate the pre-set bending line of the sheet metal, and the laser spot covers an area 5-10mm beyond the bending line; at the same time, the rolling head moves with the laser head and applies rolling pressure to the heated sheet metal to achieve vertical upward bending, with the bending height consistent with the short side of the H-shaped tube; after each bending, the temperature measuring camera detects the temperature of the bending area in real time, and if the temperature is lower than the target value, the laser power is automatically increased by 5%; The second bending section is a horizontal inward bending section during the forming stage of the closed rectangular tube; after the first bending section is completed, the robot adjusts its posture, and the laser head and the rolling head synchronously turn to the horizontal direction to bend the sheet material horizontally inward. The bending length is consistent with 1 / 2 of the long side of the H-shaped tube; during the horizontal bending process, the bending length is detected by the displacement sensor to ensure that the length deviation is ≤±0.1mm; at the same time, the guide wheel with lateral pressure of 1-3kN is in close contact with the side of the sheet material to prevent the sheet material from turning outward. The third bending section is a vertical downward bend in the closed rectangular tube forming stage. After the second bending section is completed, the robot adjusts its posture again, and the laser head and rolling head turn vertically downward to bend the sheet metal vertically downward. The bending depth is consistent with the vertical upward bending height, so that the second end of the sheet metal contacts the upper surface of the unbent sheet metal to form a closed rectangular tube. At this time, the contact area is pressed by a robot-driven pressure block with a pressure of 3-5kN to ensure that the gap is ≤0.1mm. The cross-sectional dimensional tolerance of the closed rectangular tube is controlled within ±0.1mm, the corner R / t=2-3, and the thinning rate is ≤8%. The fourth bending section is a vertically upward bending section in the C-shaped tube forming stage; after the closed rectangular tube is formed, the robot drives the laser head and the rolling head to move to the unbent area on the other side of the sheet, performs laser preheating on the preset bending line, and then performs a vertically upward bending, with the bending height consistent with the short side of the H-shaped tube; during the process, the rolling pressure is monitored by a force sensor, and if the rolling pressure exceeds the set value by 10%, the bending speed is automatically reduced to avoid the sheet breaking; The fifth bending section is a horizontal inward bending section in the C-shaped tube forming stage; after the fourth bending section is completed, the laser head and the rolling head turn to the horizontal direction to bend the sheet material horizontally inward. The bending length is consistent with 1 / 2 of the long side of the H-shaped tube to form a C-shaped tube; the first end contacts the outer surface of the closed rectangular tube, and the contact gap is detected by a vision camera to ensure that the contact gap is ≤0.1mm; if the gap is too large, the position of the rolling head is adjusted, and 1-2 more fine-tuning bends are added.

[0016] In a preferred embodiment, in step S20, after the robot bends and shapes the sheet metal, the forming quality is inspected and forming defects are controlled; the forming defect control includes wrinkling control, edge crack control, and springback tolerance control. Wrinkling control is implemented in areas with a bending radius ≤50mm, including increasing the pressure of the follow-up pressure block to 5kN, reducing the laser spot oscillation amplitude to 1mm, and reducing the bending angle per pass to 5°; the wrinkling incidence rate is controlled to below 1%; Edge crack control in the cold work hardening zone of AHSS includes increasing the laser preheating temperature to 800℃, increasing the number of passes to 15, reducing the bending angle per pass to 6°, and performing local laser heating of the sheet edge to 700℃ and holding it at that temperature for 10 seconds for pre-softening treatment; the edge crack incidence rate is controlled to below 3%. Springback tolerance control includes increasing the target temperature by 20-50℃, increasing the rolling pressure by 10%-15%, adding 1-2 passes of correction bending after forming, with each pass being 1°-2°; and controlling the springback angle to 0.3°-0.8°.

[0017] In a preferred embodiment, in step S30: Before welding, clean the interface: use high-pressure air with a pressure of 0.5-0.8MPa to blow away dust and metal debris at the interface; if there is oxide scale at the interface, use a 120-mesh steel wire brush to grind it, and the surface roughness Ra after grinding is ≤1.6μm; Before welding, the interface is pre-formed and temporarily engaged: at the interface between the first end and the closed rectangular tube, a pressure of 3-5kN is applied by the robot gripper to form a temporary engagement with an engagement length of 3-5mm; at the same time, a guide slope of 15-30° is machined at the interface to reserve an assembly gap of 0.1-0.5mm to accommodate the dimensional deviation of the sheet metal. Before welding, preset the welding parameters: laser power 3000-4000W, welding wire ER100S-G with a diameter of 1.2mm, wire feed speed 8-12m / min, welding speed 300-500mm / min, defocusing amount 2-3mm, and shielding gas Ar+2%O2 with a flow rate of 15-20L / h. Arc initiation and termination during welding: When initiating the arc, the laser power is gradually increased from 50% to the set value within 0.5-1 seconds to avoid instantaneous high temperature causing the welding wire to burn out; when terminating the arc, the laser power is gradually reduced to 50% within 0.5-1 seconds, and the wire feeding speed is reduced simultaneously to avoid the formation of arc craters. Welding process is monitored in real time: the weld formation is monitored by an industrial camera with a frame rate of 30fps, and the weld toe transition radius and weld reinforcement are detected; if the weld toe transition radius is <0.5mm, the shielding gas flow rate is increased by 5%; if the weld reinforcement is >1.5mm, the welding speed is reduced by 10%; at the same time, a temperature measuring camera detects the HAZ temperature to ensure that the peak HAZ temperature is ≤1000℃ or ≤600℃ to avoid grain coarsening; If the sheet thickness is >3mm during welding, use multi-pass welding (2-3 passes). The first pass fills half the depth of the interface, and the second pass fills until the interface is flush. There should be a 2-3 minute interval between multiple passes, and wait for the HAZ temperature to drop below 300℃ to avoid heat accumulation and deformation. Visual inspection of weld quality after welding: After welding, the appearance of the weld is inspected visually with a 10x magnifying glass. It is required that there are no defects such as cracks, porosity, or lack of fusion; the weld reinforcement height is 0.5-1.5mm, the weld width deviation is ≤±0.5mm, and the weld toe transition radius is ≥0.5mm. Non-destructive testing in weld quality inspection after welding: Ultrasonic flaw detector is used to perform non-destructive testing on the weld, with a testing frequency of 5MHz and a probe angle of 45°, to ensure that the internal porosity of the weld is ≤0.5% and the unfused length is ≤1mm; For high-strength steel welds, magnetic particle testing is additionally performed to detect surface cracks. Mechanical property sampling inspection in weld quality inspection after welding: Three workpieces are randomly selected from each batch for weld tensile test. The tensile strength of the weld is required to be no less than 90% of the base material. At the same time, a bending test is carried out with a bending angle of 180° and a bending radius of 2 times the plate thickness. The weld is required to be free of cracks.

[0018] In a preferred embodiment, in step S40: Parameter settings for aerosol shaping and cooling: equivalent cooling rate 150-200℃ / s, spray coverage area 2-3 times that of weld toe HAZ, and cooling medium is deionized water + 5% rust inhibitor. Aerosol shaping and cooling process control: After welding, the robot moves the spray nozzle to the weld area, and the distance between the spray nozzle and the weld is set to 10-20mm; the weld temperature is monitored in real time by a temperature measuring camera, and spray cooling is started when the temperature drops from the peak to 600℃; during the cooling process, the temperature difference between the thickness and the weld is controlled to be ≤40-60℃. If the temperature difference exceeds the limit, the linear speed is automatically reduced by 20% and the spray flow rate is increased by 30%. Microstructure analysis after cooling: After cooling, the weld microstructure was observed using a metallographic microscope. The high-strength steel weld was a martensitic structure with a content of ≥90% and a grain size of ≤10μm; the aluminum alloy weld was mainly α-Al solid solution with no obvious precipitates. Correction pressure setting: The correction pressure is set according to the cross-sectional dimensions of the tube. The correction pressure is 8-10kN for a 110mm×34mm cross-section and 10-12kN for a 120mm×40mm cross-section. The correction pressure is monitored in real time by a force sensor, and the deviation is ≤±0.5kN. The straightening process includes: fixing the cooled H-shaped tube onto the straightening fixture, and straightening the cross-section as a whole using a hydraulic straightening head with a stroke accuracy of ±0.01mm, focusing on straightening the middle ribs and corners; after straightening, using a laser profilometer to check the cross-sectional dimensions to ensure a dimensional tolerance of ±0.1mm; then straightening the straightness by applying a pressure of 2-5kN through straightening rollers spaced 500-1000mm apart, resulting in a straightness of ≤0.5mm / m after straightening. Beneficial effects

[0019] This embodiment provides a method for manufacturing H-shaped high-strength steel automotive parts based on laser roll forming. This method enables high-precision, low-springback manufacturing of bumpers made of high-strength steel, ultra-high-strength steel, and lightweight materials, significantly improving product precision, strength, and lightweighting. It also overcomes common industry challenges associated with traditional processes, such as numerous processing steps, high springback, and high energy consumption. This manufacturing method offers the following advantages: 1. High forming efficiency: The number of forming passes is reduced from the traditional 8-10 passes to 4-5 passes, a reduction of 37.5%, and the production cycle time is shortened from 180 seconds to 120 seconds, a reduction of 33.3%, which is suitable for the needs of flexible production lines.

[0020] 2. Superior precision control: The springback angle is reduced to 1-2° (traditionally 5-8°), a reduction of 75%; the straightness error is ≤±0.5mm / m, which is better than the traditional ±1.5mm / m; the corner size tolerance is ±0.2mm, the corner thinning rate is <10%, and the R / t value is reduced to 1.5.

[0021] 3. Strong material adaptability: Supports a variety of high-strength materials, with short changeover time and reduced equipment investment by 30% (traditionally 2-4 hours).

[0022] 4. Energy saving and environmental protection: Local heating saves 40% more energy than induction heating, the weld pass rate is >98%, and carbon emissions are reduced by 20%.

[0023] 5. Good economic efficiency: The overall cost is reduced by 15%, making it especially suitable for small-batch customized production.

[0024] These metrics highlight the breakthroughs this invention achieves in precision, efficiency, and sustainability. This invention, through laser roll forming technology, enables the efficient and high-precision manufacturing of automotive bumpers, providing the industry with a lightweight solution. In the future, it can be combined with digital twin technology to further optimize intelligent process decision-making capabilities. This invention not only solves the bottlenecks of traditional processes but also provides a new paradigm for innovation in automotive parts manufacturing.

[0025] Specific embodiments of the present invention are disclosed in detail with reference to the following description and accompanying drawings, indicating how the principles of the invention can be employed. It should be understood that the embodiments of the present invention are not limited in scope as a result.

[0026] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0027] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0029] Figure 1The flowchart of the steps of a manufacturing method for a Japanese character-shaped automotive high-strength steel part based on laser roll forming provided in this embodiment; Figure 2 The schematic cross-sectional structure diagram of a "Japanese character-shaped" automotive bumper provided in this embodiment; Figures 3(a)-3(f) It is adopted Figure 1 The schematic cross-section diagram during the processing of manufacturing a "Japanese character-shaped" automotive bumper by the manufacturing method in.

[0030] Explanation of reference numerals: 1. Japanese character-shaped tube; 2. Closed rectangular tube; 3. C-shaped tube; 4. Interface; 5. Sheet metal; 51. First end; 52. Second end; 61. First bending section; 62. Second bending section; 63. Third bending section; 64. Fourth bending section; 65. Fifth bending section. Specific embodiments

[0031] In order to enable those skilled in the art to better understand the technical solutions in this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this invention. Obviously, the described embodiments are only a part of the embodiments of this invention, rather than all of the embodiments. Based on the embodiments in this invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the scope of protection of this invention.

[0032] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be another intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be another intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of this invention. The terms used herein in the specification of this invention are only for the purpose of describing specific embodiments and are not intended to limit this invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0034] The inventors discovered that the limitations of the background technology highlight the shortcomings of existing technologies in terms of high precision, flexibility, and energy efficiency. Laser-assisted roll forming (LARF), an advanced flexible manufacturing technology that has emerged in recent years, works by using a high-energy laser to locally preheat the deformation zone of the sheet metal, reducing the material's yield strength, and then combining this with progressive roll forming to achieve precision bending. This technology has been widely used in the aerospace and rail transportation fields. For example, research by the Fraunhofer Institute in Germany has shown that LARF can be used for forming titanium alloy profiles, improving springback control accuracy by more than 40%; related research at Harbin Institute of Technology has also confirmed its advantages in forming AHSS materials. Compared to traditional processes, the outstanding advantages of LARF are: 1. Localized heating with low energy consumption: The laser only heats the area to be deformed (approximately 5-20 mm²), rather than the entire workpiece. The energy consumption is only 30%-50% of that of electromagnetic induction heating and 20%-30% of that of hot stamping, which meets the energy conservation and emission reduction requirements of the automotive industry. 2. Low springback and high precision: Laser heating reduces the yield strength of the material and decreases the elastic recovery. The springback angle of AHSS bending can be controlled at 0.3°-0.8°, which is much lower than the 2°-5° of cold bending. At the same time, progressive rolling can achieve precise deformation of ≤8° per pass, and the cross-sectional dimensional tolerance reaches ±0.1mm. 3. Simplified molds and quick changeover: No special large molds are required, only a universal rolling head and guide device are needed. When changing molds, only the robot program and rolling head parameters need to be adjusted, which takes 30-60 minutes. It is suitable for small-batch production of multiple varieties. 4. Wide material tolerance: It can form AHSS, UHSS and 6xxx series aluminum alloys with a thickness of 1-5mm, especially suitable for high-strength materials that are difficult to cold bend (such as B1500HS, BR1500HS), solving the material compatibility bottleneck of traditional processes; Good compatibility with welding: The material structure after laser heating is uniform and can be directly used for laser filler wire welding, adapting to assembly gaps of 0.1-0.5mm, improving the weld pass rate to over 98%, and reducing HAZ embrittlement and increasing toughness by 10%-15%.

[0035] Therefore, introducing LARF technology into automotive bumper manufacturing is an inevitable choice to meet the demands for lightweighting and high precision. Firstly, as a long component, the bumper has extremely high requirements for straightness (≤±0.5mm / m) and cross-sectional consistency; LARF's progressive rolling process effectively avoids thermal deformation caused by overall heating. Secondly, bumper materials are becoming increasingly diversified (e.g., UHSS, 6xxx aluminum); LARF can adapt to different materials by adjusting laser parameters, avoiding the investment in dedicated molds required by traditional processes. Finally, the demand for small-batch customized bumpers is increasing (e.g., the accelerated iteration of new energy vehicle models); LARF's flexible robotic units reduce investment by 30% compared to rigid production lines. Therefore, this invention introduces LARF technology into the manufacturing of "H-shaped" automotive bumpers, primarily based on the following core needs: 1. Urgent need for material upgrades: As bumper materials are upgraded to AHSS / UHSS, traditional cold bending processes are difficult to form, while LARF technology can solve the problem of low plasticity of high-strength materials through local thermal softening, achieving precise forming with small R / t and low thinning. 2. The need for production model transformation: The current automotive market is showing a trend of "multiple varieties, small batches, and customization" (such as 5-10 new models of new energy vehicles are launched every year). Traditional processes have high changeover costs and long cycles, while LARF technology has fast changeover and low mold costs, which can meet the customization needs of 1,000-10,000 pieces per year. 3. The need for a balance between lightweighting and performance: Bumpers need to reduce weight while ensuring collision safety performance. LARF technology can achieve a small radius cross-section with R / t=1.5-3, improve material utilization by 8%-12%, reduce weight by 5%-10%, and at the same time ensure tensile strength ≥1600MPa through closed-loop temperature control to meet safety requirements. 4. The need for cost and efficiency optimization: Traditional hot stamping and hydroforming equipment have large investments and low efficiency, while LARF technology requires only 1 / 3 of the investment for hot stamping and 1 / 5 of the investment for hydroforming, and the forming time for a single part is reduced by 30%-50%, which can significantly reduce manufacturing costs.

[0036] Against this backdrop, this invention overcomes the process bottlenecks of CN110576292B and CN110038963B by innovatively integrating "laser preheating + rolling + laser welding + aerosol cooling" to achieve triple optimization of precision, efficiency, and cost. Key innovations include: employing a robot carrying a laser head and a rolling head for collaborative operation to achieve localized heating and progressive forming; introducing laser filler wire welding to ensure high weld strength; and combining aerosol cooling to control microstructure properties. These innovations not only solve the springback and energy consumption problems of traditional processes but also provide a scalable solution for automotive lightweighting.

[0037] Please see Figure 1See Figure 3. This application provides a method for manufacturing a high-strength steel automotive part with a H-shape based on laser roll forming, comprising the following steps: Step S10: Complete the preparation work; the preparation work includes sheet 5 and surface preparation, power-on self-test, tooling and zero-position calibration, robot TCP calibration; the robot is connected to a rolling head and a laser head; sheet 5 has a first end 51 and a second end 52 with opposite sides; Step S20: Use a robot to bend and form the sheet metal 5; during the bending and forming process, the laser head irradiates the outer surface of the area to be bent, and a rectangular or oscillating laser spot is used to cover the deformation area. The laser head and the rolling head maintain a predetermined distance, and the bending angle of each pass is less than or equal to 8°; for the horizontally set sheet metal 5, the second end 52 is first bent vertically upward, horizontally inward, and vertically downward in sequence, so that the second end 52 contacts the upper surface of the unbent sheet metal 5 to form a closed rectangular tube 2; then the first end 51 is bent vertically upward and horizontally inward in sequence to form a C-shaped tube 3, so that the first end 51 contacts the outer surface of the bend of the closed rectangular tube 2 to form a closure; Step S30: Laser filler wire welding is used at the two interfaces 4 to form a closed H-shaped tube 1, as shown. Figure 2 As shown; Step S40: Post-weld aerosol shaping, cooling and straightening; including aerosol shaping and cooling, straightening, online detection and feedback optimization; aerosol shaping and cooling includes shaping and cooling by covering the weld toe and bending area with aerosol, the spray coverage area being 1.5 to 5 times the heat-affected zone of the laser molten pool at the weld toe; the equivalent cooling rate is 50℃ / s to 200℃ / s, the thickness-to-temperature difference is controlled to be less than or equal to 40℃ to 60℃, and if the temperature difference exceeds the limit, the linear speed is automatically reduced and the spray flow rate is increased.

[0038] This embodiment provides a method for manufacturing H-shaped high-strength steel automotive parts based on laser roll forming. Based on the principle of laser-assisted roll forming, it integrates advanced processes such as high-energy laser precision heating, robotic progressive roll forming, laser wire welding, and atomized cooling to achieve high-precision, low-springback manufacturing of bumpers made of high-strength steel, ultra-high-strength steel (AHSS / UHSS), and lightweight materials. This invention is particularly suitable for the flexible, small-batch customized production of bumpers for new energy vehicles and high-end passenger vehicles, significantly improving product precision, strength, and lightweighting while overcoming common industry challenges such as numerous passes, high springback, and high energy consumption inherent in traditional processes.

[0039] The purpose of this invention is to overcome the limitations of existing automotive bumper forming processes (cold bending, hot stamping, water expansion) and proprietary technologies for H-shaped tubes (CN110576292B, CN110038963B), and to provide a method for manufacturing H-shaped automotive bumpers based on laser heating-assisted roll forming, achieving the following objectives: 1. Reduce the forming springback of the H-shaped tube, control the bending springback angle to 0.3°-0.8°, and the cross-sectional dimension tolerance to ±0.1mm; 2. Simplify the tooling system and reduce changeover time to 30-60 minutes, adapting to multi-variety, small-batch production; 3. Reduced energy consumption and manufacturing costs: Energy consumption is reduced by 50%-70% compared to electromagnetic induction heating in CN110576292B, and unit cost is reduced by 15%-20%; 4. Improve weld quality and mechanical properties, with a weld pass rate of ≥98%, a bumper tensile strength of ≥1600MPa (high-strength steel), and an elongation of ≥7% (high-strength steel).

[0040] The manufacturing method of this invention achieves low springback forming through closed-loop temperature control and progressive rolling; and forms a closed cross-section by laser welding. Compared with existing cold bending + conventional welding, this method has fewer passes, lower springback, higher corner quality and weld stability, greater material tolerance, is applicable to various high-strength steels, requires no molds, has low cost, is suitable for small-batch, multi-variety production, and has high processing precision, and can also be customized according to user requirements.

[0041] Compared with existing technologies, the forming method of the H-shaped tube described in this invention reduces the number of passes by 10-30%, increases cycle time, significantly reduces springback, improves corner dimension consistency, and makes weld formation and strength more stable. It is also compatible with multiple materials and platforms, and has low switching costs.

[0042] This invention adopts a four-stage process system of "preparation-laser preheating and rolling-laser filler wire welding-air mist cooling and shaping" to form a closed-loop and controllable intelligent manufacturing process.

[0043] In this embodiment, the preparatory work in step S10 is used to ensure that the materials and equipment are in optimal condition, laying the foundation for subsequent forming. In step S10, the preparation of sheet metal 5 and its surface includes degreasing and drying the surface of sheet metal 5 through an upstream leveling and cleaning unit, and checking for edge burrs.

[0044] Specifically, the material of sheet metal 5 is selected as high-strength steel according to the bumper design requirements. B1500HS and BR1500HS are preferred high-strength steels with a yield strength greater than or equal to 1500MPa, a tensile strength of 1600mPa~1800mPa, and an elongation greater than or equal to 8%. The thickness of sheet metal 5 is set to 1mm~5mm according to collision requirements, with a thickness deviation less than or equal to ±0.05mm.

[0045] Furthermore, surface preparation includes leveling: a two-roll or four-roll screed is used to level the sheet material 5. The leveling pressure is set to 5-8 MPa according to the thickness of the sheet material 5 (5-6 MPa for sheet material 5 with a thickness of 1-2 mm, and 7-8 MPa for sheet material 5 with a thickness of 3-5 mm), to ensure that the flatness of the sheet material 5 is less than or equal to 0.2 mm / m; and the surface roughness of the rollers is less than or equal to 0.8 μm, to avoid scratching the surface of the sheet material 5.

[0046] Further, surface preparation includes cleaning and drying: removing oil, scale, and other impurities from the surface of sheet 5 using a spray cleaning machine, employing an alkaline cleaning agent with a concentration of 5% to 8% (such as a mixed solution of sodium hydroxide and sodium carbonate), cleaning at a temperature of 40℃ to 60℃ for 2 to 3 minutes; subsequently drying in a hot air drying oven at 80℃ to 120℃ for 1 to 2 minutes, ensuring that the surface moisture content of sheet 5 is less than or equal to 0.1%.

[0047] Furthermore, surface preparation includes burr detection: a laser thickness gauge is used to detect burrs on the edge of the sheet metal 5 with a detection accuracy of ±0.001mm, ensuring that the burr height is less than or equal to 0.1mm; if the burrs exceed the standard, they are repaired using a grinding wheel with a grit size of 120~180 mesh, and the edge roughness Ra after repair is less than or equal to 1.6μm.

[0048] In this embodiment, the power-on self-test in step S10 aims to ensure that the equipment is in normal working condition and to avoid forming defects due to equipment failure. The power-on self-test includes starting the main control and robot servo systems, and checking the self-test status of the laser head, spray system, temperature camera, force and displacement sensors. Specifically, the power-on self-test includes: main control and servo system testing, laser head testing, spray system testing, sensor calibration, and alarm system testing.

[0049] The main control and servo system testing includes: starting the main control PLC, establishing communication with the robot's servo system, and checking that the communication delay is less than or equal to 10ms; checking the servo motor current, speed and other parameters through the PLC diagnostic interface to ensure that the current fluctuation is ≤±5% and the speed deviation is ≤±1rpm.

[0050] Further, the laser head testing includes: starting the fiber laser, performing a power stability test, setting the power to 1000W~5000W, with an interval of 1000W, maintaining each power point for 5 minutes, and detecting power fluctuations ≤±2%; at the same time, checking the coaxiality of the laser optical path, using a laser collimator to ensure that the optical path deviation is ≤0.05mm / m.

[0051] Further testing of the spray system includes: starting the aerosol cooling system and checking the flow rate of each nozzle, with the flow rate set to 5-15 L / h; adjusting the flow rate according to the thickness of the sheet material 5, with a flow rate of 5-10 L / h for sheet material 5 with a thickness of 1-2 mm and a flow rate of 10-15 L / h for sheet material 5 with a thickness of 3-5 mm; the flow rate error ≤ ±5%; and checking the spray uniformity using filter paper testing, with the spray coverage area deviation ≤ ±10%.

[0052] Furthermore, sensor calibration includes: temperature accuracy calibration of the temperature measuring camera using a standard blackbody furnace with a temperature range of 500-1000℃, achieving a calibration accuracy of ±2℃; range calibration of the force sensor, with a range of 0-50kN and an accuracy of ±0.1%; and linearity calibration of the displacement sensor, with a linearity of ±0.005mm.

[0053] Furthermore, the alarm system test includes: simulating equipment malfunctions (such as excessive laser head power or loss of sensor signals), checking whether the audible and visual alarm system is triggered normally, with an alarm response time ≤100ms, ensuring that the equipment stops in case of malfunction to avoid damage to the workpiece.

[0054] In this embodiment, in step S10, the tooling and zero-position calibration includes selecting the "H-shaped" cross-section roller group for this batch, using the standard calibration block to perform zero-position, roll gap, and centering calibration of the rolling head, and recording the reference code. Specifically, the tooling and zero-position calibration includes: standard calibration block preparation, rolling head zero-position calibration, roll gap calibration, centering calibration, and reference code storage.

[0055] The preparation of the standard alignment block includes: selecting a standard alignment block made of 45 steel with a hardness of HRC28-32, whose size is consistent with the cross section of the tube 1 to be formed (e.g., 110mm×34mm), with a dimensional accuracy of ±0.005mm and a surface roughness Ra≤0.8μm; and setting 3 reference points on the standard alignment block for laser positioning.

[0056] Furthermore, the zero-position calibration of the rolling head includes: fixing the standard calibration block on the worktable, using a robot to drive a rolling head made of WC-Co material with a hardness of HRC60-65 to fit against the surface of the standard calibration block, recording the coordinates of the rolling head in the X, Y, and Z directions, and setting them as the zero position; repeating the calibration 3 times to ensure a repeatability accuracy of ±0.01mm; the diameter of the rolling head roller is set to 50-100mm according to the thickness of the sheet material 5 (the diameter of the rolling head roller is 50-60mm for 1-2mm thick sheet material 5, and 80-100mm for 3-5mm thick sheet material 5), and the width of the rolling head roller is 2-3mm larger than the width of the sheet material 5.

[0057] Furthermore, the roll gap calibration includes: setting the roll gap according to the thickness of sheet 5, with the roll gap value being 0.05~0.1mm larger than the thickness of sheet 5 to compensate for the elastic deformation of sheet 5. For example, the roll gap of sheet 5 with a thickness of 2mm is set to 2.05-2.1mm; and checking the roll gap with a feeler gauge with an accuracy of ±0.001mm to ensure that the roll gap deviation is ≤±0.01mm.

[0058] Further, the centering calibration includes: using a laser centering instrument to detect the alignment of the sheet 5 conveying path with the rolling head, adjusting the position of the worktable so that the deviation between the center of the sheet 5 and the center of the rolling head is ≤0.05mm; after centering, recording the worktable coordinates as a reference for subsequent forming.

[0059] Furthermore, the reference code storage includes storing reference data such as zero coordinates, roll gap parameters, and centering coordinates into the PLC's encrypted storage unit to prevent accidental modification; at the same time, a calibration report is generated, recording information such as calibration time, operator, and equipment status for easy traceability.

[0060] In this embodiment, in step S10, the robot TCP calibration includes: laser focus calibration, nozzle coaxiality calibration, and TCP repeatability accuracy test. TCP includes the laser focus and the nozzle.

[0061] The laser focus calibration includes: using a laser focus test card (IPG-specific test card), adjusting the robot's posture so that the laser focus falls on the center of the test card, and recording the focus coordinates; and adjusting the position of the focusing lens with a focal length of 150-200mm to ensure that the focus diameter deviation is ≤±0.1mm.

[0062] Further, nozzle coaxiality calibration includes: installing a brass nozzle with an inner diameter of 2-5mm at the end of the laser head, and using a coaxiality tester to check the coaxiality between the nozzle center and the laser focus to ensure that the coaxiality is ≤0.05mm; if the coaxiality exceeds the standard, adjust the nozzle fixing bolts until the requirements are met.

[0063] Furthermore, the TCP repeatability accuracy test includes: the robot moves the laser head and the rolling head to 5 different positions in the workspace, stops at each position and records the TCP coordinates, calculates the repeatability accuracy, and ensures a repeatability accuracy of ±0.02mm; the calibration frequency is set to once every 8 hours, and if the equipment is shut down for more than 2 hours, recalibration is performed.

[0064] In this embodiment, laser preheating and progressive rolling forming in step S20 are the core processes of the present invention. Through the synergistic effect of local laser heating and progressive rolling, the low springback forming of the H-shaped tube 1 is achieved. Moreover, laser preheating and rolling forming are carried out simultaneously, divided into two stages: "forming of closed rectangular tube 2" and "forming of C-shaped tube 3".

[0065] In step S20, before the robot bends and shapes the sheet 5, preset process parameters are loaded according to the material and cross-sectional dimensions of the sheet 5. The process parameters include laser parameters, rolling parameters, and temperature control parameters.

[0066] The laser parameters include laser power, spot type, linear velocity, and predetermined distance. The laser power is 1500W-2500W (2000W for a 2mm thickness of B1500HS, and 2500W for a 3mm thickness). The spot type is either a rectangular spot or a wobbling spot. Rectangular spots are 2mm x 5mm in size, while wobbling spots have a wobbling amplitude of 1-3mm and a frequency of 50-200Hz. For high-strength steel, the wobbling amplitude is 2-3mm. The linear velocity is 300-800mm / min (300-500mm / min for high-strength steel). The predetermined distance (i.e., hysteresis distance) between the laser head and the rolling head is 5-15mm (10-15mm for high-strength steel, adjusted according to the material's thermal conductivity; a higher thermal conductivity results in a smaller hysteresis distance).

[0067] Furthermore, the rolling parameters include the number of passes, rolling pressure, and rolling speed. The number of passes is determined based on the total bending angle (usually 90°) and the maximum bending angle per pass (≤8° for steel). For example, high-strength steel requires 12 passes (7.5° per pass) for a 90° bend. The rolling pressure is 8-15 kN (10-12 kN for 5 passes for 2mm thick plates, and 13-15 kN for 5 passes for 3mm thick plates). The rolling speed is synchronized with the laser linear speed, at 300-800 mm / min, to ensure coordinated rolling and heating.

[0068] Furthermore, the temperature control parameters include the target temperature window, temperature fluctuation threshold, and compensation strategy. The target temperature window is 600-800℃ (700-750℃ for B1500HS and 650-700℃ for BR1500HS). The temperature fluctuation threshold is ±10℃ (high-strength steel) or ±15℃ (aluminum alloy). The compensation strategy includes: when the temperature is below the target lower limit, increasing the laser power by 5%-10% or decreasing the linear speed by 10%-20%; when the temperature is above the target upper limit, decreasing the laser power by 5%-10% or increasing the linear speed by 10%-20%.

[0069] In this embodiment, before using a robot to bend and shape the sheet metal 5 in step S20, the following steps are also included: The sheet 5 is positioned and fixed by conveying the sheet 5; the pre-processed sheet 5 is conveyed to the worktable by a servo feeder with an accuracy of ±0.05mm. The feeding length is set according to the unfolded length of the H-shaped tube (e.g., the unfolded length of the H-shaped tube 1 with a cross section of 110mm×34mm is about 280mm). Positioning and clamping of sheet metal 5 is performed; pneumatic grippers with a clamping force of 5-10kN are used to fix sheet metal 5 on the worktable. Rubber pads with a thickness of 2mm and a hardness of Shore A60 are attached to the contact parts between the grippers and sheet metal 5 to avoid scratching sheet metal 5; the positioning reference is two adjacent edges of sheet metal 5, and the positional deviation of sheet metal 5 is ensured to be ≤±0.05mm by positioning pins with an accuracy of ±0.005mm. Visual positioning confirmation is performed during the positioning and fixing of sheet material 5; the industrial camera is activated to capture the positioning status of sheet material 5, and the position deviation is compared with the preset positioning template. If the deviation exceeds ±0.05mm, the position of the servo feeder is automatically adjusted until the requirements are met.

[0070] Specifically, in step S20, such as Figures 3(a)-3(f) As shown, the bending and forming of sheet 5 using a robot includes a first bending segment 61, a second bending segment 62, a third bending segment 63, a fourth bending segment 64, and a fifth bending segment 65.

[0071] As shown in Figure 3(b), the first bending segment 61 is a vertically upward bending segment of the closed rectangular tube 2 during the forming stage; the robot drives the laser head to irradiate the preset bending line of the sheet 5 (50-60mm away from the edge of the sheet 5, set according to the cross-section of the H-shaped tube 1), and the laser spot covers a range of 5-10mm beyond the bending line to ensure that the area to be deformed is fully heated; at the same time, the rolling head moves with the laser head and applies rolling pressure to the heated sheet 5 to achieve vertical upward bending, and the bending height is consistent with the short side of the H-shaped tube (e.g., 34mm); after each bending, the temperature measuring camera detects the temperature of the bending area in real time, and if the temperature is lower than the target value, the laser power is automatically increased by 5%.

[0072] Furthermore, as shown in Figure 3(c), the second bending segment 62 is a horizontal inward bending segment during the forming stage of the closed rectangular tube 2; after the first bending segment 61 is completed, the robot adjusts its posture, and the laser head and the rolling head synchronously turn to the horizontal direction to bend the sheet 5 horizontally inward. The bending length is consistent with 1 / 2 of the long side of the H-shaped tube (e.g., 55mm); during the horizontal bending process, the bending length is detected by the displacement sensor to ensure that the length deviation is ≤±0.1mm; at the same time, the guide wheel with lateral pressure of 1-3kN is in close contact with the side of the sheet 5 to prevent the sheet 5 from turning outward.

[0073] Furthermore, as shown in Figure 3(d), the third bending segment 63 is a vertically downward bending segment in the forming stage of the closed rectangular tube 2; after the second bending segment 62 is completed, the robot adjusts its posture again, and the laser head and the rolling head turn to the vertically downward direction to bend the sheet 5 vertically downward. The bending depth is consistent with the vertically upward bending height (34mm), so that the second end 52 of the sheet 5 contacts the upper surface of the unbent sheet 5 to form the closed rectangular tube 2; at this time, the contact part is pressed by the robot follow-up pressure block with a pressure of 3-5kN to ensure that the gap is ≤0.1mm; the cross-sectional dimensional tolerance of the closed rectangular tube 2 is controlled within ±0.1mm, the corner R / t=2-3, and the thinning rate is ≤8%.

[0074] Furthermore, as shown in Figure 3(e), the fourth bending segment 64 is a vertically upward bending segment during the forming stage of the C-shaped tube 3; after the closed rectangular tube 2 is formed, the robot drives the laser head and the rolling head to move to the unbent area on the other side of the sheet 5, performs laser preheating on the preset bending line, and then performs a vertical upward bending, with the bending height consistent with the short side of the H-shaped tube (34mm); during the process, the rolling pressure is monitored by a force sensor, and if the rolling pressure exceeds the set value by 10%, the bending speed is automatically reduced to avoid the sheet 5 from cracking.

[0075] Furthermore, as shown in Figure 3(f), the fifth bending segment 65 is a horizontal inward bending segment during the forming stage of the C-shaped tube 3; after the fourth bending segment 64 is completed, the laser head and the rolling head turn to the horizontal direction to bend the sheet 5 horizontally inward, and the bending length is consistent with 1 / 2 of the long side of the H-shaped tube (55mm), forming the C-shaped tube 3; the first end 51 contacts the outer surface of the closed rectangular tube 2, and the contact gap is detected by a vision camera to ensure that the contact gap is ≤0.1mm; if the gap is too large, the position of the rolling head is adjusted, and 1-2 more fine-tuning bends are added.

[0076] In this embodiment, in step S20, after the robot bends and forms the sheet metal 5, the forming quality is inspected and forming defects are controlled. Forming defect control includes wrinkling control, edge cracking control, and springback tolerance control. Since wrinkling, edge cracking, and springback tolerance defects are prone to occur during the forming process, targeted control measures are necessary.

[0077] The forming quality inspection includes: after the C-shaped tube 3 is formed, a laser profilometer (accuracy ±0.01mm) is used to scan the formed cross section and compare it with the preset cross section template to detect parameters such as cross section size, corner radius, and thinning rate; if the corner radius exceeds the standard (R / t>3), the laser power is increased by 10% and the bending is repeated once; if the thinning rate exceeds the standard (>8%), the rolling pressure is reduced by 10% and the tube is reformed.

[0078] Furthermore, wrinkling control is implemented in areas with small bending radii (≤50mm), including: ① increasing the pressure of the follow-up pressure block to 5kN; ② reducing the laser spot oscillation amplitude to 1mm; ③ reducing the bending angle per pass to 5°. Through these measures, the wrinkling incidence rate can be controlled to below 1%.

[0079] Furthermore, edge crack control is implemented in the cold-work hardening zone of the AHSS, including: ① increasing the laser preheating temperature to 800℃; ② increasing the number of passes to 15 and reducing the bending angle per pass to 6°; ③ performing a pre-softening treatment on the edge of the sheet material by locally heating it to 700℃ with laser and holding it at that temperature for 10 seconds. Through these measures, the edge crack incidence rate can be controlled to below 3%.

[0080] Furthermore, excessive springback is mainly caused by insufficient temperature or insufficient rolling pressure. Control measures include: ① increasing the target temperature by 20-50℃; ② increasing the rolling pressure by 10%-15%; ③ adding 1-2 passes of correction bending after forming, each pass being 1°-2°. Through the above measures, the springback angle can be controlled within 0.3°-0.8°.

[0081] In this embodiment, the following steps are also required in step S30: Before welding, clean the interface 4: use high-pressure air with a pressure of 0.5-0.8MPa to blow away the dust and metal debris at the interface 4; if there is oxide scale at the interface 4, use a steel wire brush with a particle size of 120 mesh to gently polish it. After polishing, the surface roughness Ra≤1.6μm. Before welding, pre-form and temporarily engage at interface 4: At interface 4 between the first end 51 and the closed rectangular tube 2, apply a pressure of 3-5kN by the robot gripper to form a temporary engagement with an engagement length of 3-5mm; at the same time, process a 15-30° guide slope at interface 4 and reserve an assembly gap of 0.1-0.5mm to accommodate dimensional deviations of the sheet metal 5. Before welding, preset the welding parameters: laser power 3000-4000W, welding wire ER100S-G with a diameter of 1.2mm, wire feed speed 8-12m / min, welding speed 300-500mm / min, defocusing amount 2-3mm, and shielding gas Ar+2%O2 with a flow rate of 15-20L / h. Arc initiation and termination during welding: When initiating the arc, the laser power is gradually increased from 50% to the set value within 0.5-1 seconds to avoid instantaneous high temperature causing the welding wire to burn out; when terminating the arc, the laser power is gradually reduced to 50% within 0.5-1 seconds, and the wire feeding speed is reduced simultaneously to avoid the formation of arc craters. Welding process is monitored in real time: the weld formation is monitored by an industrial camera with a frame rate of 30fps, and the weld toe transition radius and weld reinforcement are detected; if the weld toe transition radius is <0.5mm, the shielding gas flow rate is increased by 5%; if the weld reinforcement is >1.5mm, the welding speed is reduced by 10%; at the same time, the temperature camera detects the HAZ temperature to ensure that the peak HAZ temperature is ≤1000℃ (high-strength steel) or ≤600℃ (aluminum alloy) to avoid grain coarsening.

[0082] If the thickness of plate 5 is greater than 3mm during the welding process, use multi-pass welding (2-3 passes). The first pass fills half the depth of interface 4, and the second pass fills until it is flush with interface 4. There should be a 2-3 minute interval between the multiple passes, and wait for the HAZ temperature to drop below 300℃ to avoid heat accumulation and deformation. Visual inspection of weld quality after welding: After welding, the appearance of the weld is inspected visually with a 10x magnifying glass. It is required that there are no defects such as cracks, porosity, or lack of fusion; the weld reinforcement height is 0.5-1.5mm, the weld width deviation is ≤±0.5mm, and the weld toe transition radius is ≥0.5mm. Non-destructive testing in weld quality inspection after welding: Ultrasonic flaw detector is used to perform non-destructive testing on the weld, with a testing frequency of 5MHz and a probe angle of 45°, to ensure that the internal porosity of the weld is ≤0.5% and the unfused length is ≤1mm; For high-strength steel welds, magnetic particle testing is additionally performed to detect surface cracks. Mechanical property sampling inspection in weld quality inspection after welding: 3 workpieces are randomly selected from each batch for weld tensile test. The tensile strength of the weld is required to be no less than 90% of the base material (tensile strength of B1500HS weld ≥1440mPa). At the same time, a bending test is carried out with a bending angle of 180° and a bending radius of 2 times the plate thickness. The weld is required to be free of cracks.

[0083] In this embodiment, the post-weld mist shaping, cooling, and straightening in step S40 aims to control the weld microstructure, eliminate internal stress, and improve dimensional accuracy. Step S40 also includes the following steps: Parameter settings for aerosol shaping and cooling: Set the cooling parameters according to the material of plate 5, such as high-strength steel (B1500HS): equivalent cooling rate 150-200℃ / s, spray coverage area is 2-3 times the weld toe HAZ (HAZ width 2-5mm, so coverage area 4-15mm²), and the cooling medium is deionized water + 5% rust inhibitor (such as sodium nitrite). Aerosol shaping and cooling process control: After welding, the robot moves the spray nozzle to the weld area. The distance between the spray nozzle and the weld is set to 10-20mm (too close a distance can easily cause spatter, while too far a distance results in low cooling efficiency). The weld temperature is monitored in real time by a temperature measuring camera. When the temperature drops from the peak to 600℃, spray cooling is activated. During the cooling process, the temperature difference between the thickness and the weld is controlled to be ≤40-60℃ (≤40℃ for high-strength steel). If the temperature difference exceeds the limit, the linear speed is automatically reduced by 20% and the spray flow rate is increased by 30%. Microstructure analysis after cooling: After cooling, the weld microstructure was observed using a metallographic microscope. The high-strength steel weld was a martensitic structure with a content of ≥90% and a grain size of ≤10μm; the aluminum alloy weld was mainly α-Al solid solution with no obvious precipitates. Correction pressure setting: The correction pressure is set according to the cross-sectional dimensions of the tube. The correction pressure is 8-10kN for a 110mm×34mm cross-section and 10-12kN for a 120mm×40mm cross-section. The correction pressure is monitored in real time by a force sensor, and the deviation is ≤±0.5kN. The straightening process includes: fixing the cooled H-shaped tube onto the straightening fixture, and straightening the cross-section as a whole using a hydraulic straightening head with a stroke accuracy of ±0.01mm, focusing on straightening the middle ribs and corners; after straightening, using a laser profilometer to check the cross-sectional dimensions to ensure a dimensional tolerance of ±0.1mm; then straightening the straightness by applying a pressure of 2-5kN through straightening rollers spaced 500-1000mm apart, resulting in a straightness of ≤0.5mm / m after straightening.

[0084] Furthermore, regarding the shaping and straightening of the S40, internal stress relief is performed as follows: for high-requirement bumpers (such as those in luxury models), low-temperature stress-relief annealing is carried out after straightening. The annealing temperature is 200-300℃ (250-300℃ for high-strength steel), the holding time is 30-60 minutes, and the cooling method is air cooling. After annealing, the internal stress relief rate is ≥60%, which avoids deformation during subsequent use.

[0085] Furthermore, regarding the online inspection and feedback optimization in S40, dimensional accuracy inspection is performed: a coordinate measuring machine (accuracy ±0.005mm) is used to perform full-dimensional inspection on the calibrated H-shaped tubes. The inspection items include cross-sectional length, width, thickness, corner radius, straightness, etc. Five pieces are inspected per batch. If the failure rate exceeds 10%, the machine is stopped and the process parameters are adjusted.

[0086] Furthermore, for the online detection and feedback optimization in S40, the mechanical performance testing is as follows: two pieces are randomly selected from each batch for tensile and impact tests (Charpy V-notch, temperature 25℃), and the impact energy of high-strength steel is ≥30J / cm²; if the mechanical performance does not meet the standard, the laser heating temperature (±50℃) or cooling rate (±20℃ / s) is adjusted.

[0087] Furthermore, for online inspection and feedback optimization in S40, data feedback and optimization involves storing inspection data (dimensions, mechanical properties, process parameters) in a cloud database and using machine learning algorithms (such as random forests) to analyze the correlation between parameters and quality, automatically optimizing subsequent process parameters. For example, if the bending angle deviation of a batch is too large (>0.1°), the algorithm automatically suggests increasing the laser power by 5% or reducing the line speed by 10%.

[0088] Furthermore, any abnormalities occurring during the S40 production process must be corrected promptly. For example, if there are microcracks in the corner area: these manifest as microcracks ≤1mm in length at the bending corner, caused by excessively low local temperature or excessive rolling pressure; corrective measures include: ① reducing the bending angle per pass by 1-2°; ② increasing the laser power on the outer surface by 5%-10%; ③ simultaneously increasing the spray flow rate by 10%-15% to accelerate the cooling rate. If the springback exceeds tolerance: this manifests as a bending angle deviation >0.8°, caused by insufficient temperature or insufficient number of passes; corrective measures include: ① increasing the corner temperature by 20-50℃; ② reducing the linear speed by 10%-20%; ③ adding 1-2 passes for corrective bending. If the weld reinforcement is too large: This is manifested as a weld reinforcement >1.5mm, caused by excessive welding power or excessive wire feed speed; Remedial measures: ① Reduce laser power by 5%-10%; ② Reduce wire feed speed by 10%-15%; ③ Optimize the focal spot position by 0.5-1mm (away from the workpiece direction); If the cross-sectional dimensions are out of tolerance: This is manifested as a cross-sectional length / width deviation >0.1mm, caused by zero-position offset of the rolling head or inaccurate positioning of plate 5; Remedial measures: ① Recalibrate the zero-position of the rolling head; ② Adjust the position of the locating pin of plate 5; ③ Add one pass for overall shaping.

[0089] In a specific application scenario, high-strength steel of material 22MnB5, with a thickness of 1.5mm, is selected as sheet material 5. First, sheet material 5 is leveled and cleaned, then clamped onto the robot's worktable with a pneumatic clamping force of 5kN. After system calibration, the laser head is preheated at a power of 2kW and a linear speed of 1m / min, and the bending is completed in 12 passes (single pass angle 7.5°). Real-time monitoring shows that the rolling pressure fluctuation in the third pass is 8%, and the system automatically increases the laser power to 2.2kW to compensate for the temperature.

[0090] After forming, the laser filler wire welding parameters were 2.5kW power and 1.5m / min speed, and the weld was found to be defect-free upon inspection. The gas mist cooling rate was controlled at 100°C / s, and the straightness error of the finished product after straightening was 0.4mm / m, the tensile strength was 1520mPa, and the weight was reduced by 12%. All process parameters were stored in a database for iterative optimization (e.g., when adapting to 6061 aluminum alloy, the temperature window was adjusted to 300-450°C). This embodiment demonstrates the high reliability and adaptability of the present invention.

[0091] It should be noted that in the description of this specification, the terms "first," "second," etc., are used only for descriptive purposes and to distinguish similar objects; there is no order between them, nor should they be construed as indicating or implying relative importance. Furthermore, in the description of this specification, unless otherwise stated, "a plurality of" means two or more.

[0092] Any numerical values ​​cited herein include all values ​​ranging from a lower limit to an upper limit, increasing by one unit, with at least two units between any lower and any higher value. For example, if the quantity of a component or the value of a process variable (e.g., temperature, pressure, time, etc.) is described as being from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in this specification. For values ​​less than 1, a unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1, etc. These are merely examples intended for explicit expression, and it can be assumed that all possible combinations of values ​​listed between the minimum and maximum values ​​are explicitly described in this specification in a similar manner.

[0093] Unless otherwise stated, all ranges include the endpoints and all numbers between them. The terms "approximately" or "about" used with ranges apply to both endpoints of the range. Thus, "approximately 20 to 30" is intended to cover "approximately 20 to approximately 30," including at least the specified endpoints.

[0094] All articles and references disclosed herein, including patent applications and publications, are incorporated herein by reference for various purposes. The term “substantially constitutes…” used to describe a combination should include the identified elements, components, parts, or steps, as well as other elements, components, parts, or steps that do not substantially affect the essential novelty of the combination. The use of the terms “comprising” or “including” to describe combinations of elements, components, parts, or steps herein also contemplates embodiments substantially constituted by such elements, components, parts, or steps. The use of the term “may” herein is intended to indicate that any described attribute included by “may” is optional.

[0095] Multiple elements, components, parts, or steps can be provided by a single integrated element, component, part, or step. Alternatively, a single integrated element, component, part, or step can be divided into multiple separate elements, components, parts, or steps. The use of "a" or "an" to describe an element, component, part, or step does not imply the exclusion of other elements, components, parts, or steps.

[0096] It should be understood that the above description is for illustrative purposes and not for limitation. Many embodiments and applications beyond the provided examples will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of this teaching should not be determined by reference to the above description, but rather by reference to the appended claims and the full scope of their equivalents. For purposes of completeness, all articles and references, including patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended as a waiver of that subject matter, nor should it be construed as an indication that the inventors have not considered that subject matter as part of the disclosed inventive subject matter.

Claims

1. A manufacturing method of a star-shaped automobile high-strength steel part based on laser roll forming, characterized by, The method comprises the following steps: Step S10: completing preparation work; the preparation work comprises plate and surface preparation, power-on self-test, tooling and zero calibration, robot TCP calibration; The robot is connected with a rolling head and a laser head; the plate has opposite first and second ends; Step S20: using the robot to perform bending forming on the plate; in the bending forming process, the laser head irradiates the outer surface of the to-be-bent region, a rectangular light spot or a wobbling light spot is used to cover the deformation region, the laser head and the rolling head are kept at a predetermined distance, and each pass bending angle is less than or equal to 8°; for the horizontally arranged plate, the second end is sequentially subjected to vertical upward bending, horizontal inward bending and vertical downward bending, so that the second end contacts the upper surface of the unbent plate to form a closed rectangular tube; then the first end is sequentially subjected to vertical upward bending and horizontal inward bending to form a C-shaped tube, so that the first end contacts the outer surface of the bending portion of the closed rectangular tube to form a closure; Step S30: laser wire filling welding is performed at two interfaces to form a closed day-shaped tube; Step S40: post-welding gas mist setting cooling and straightening; the gas mist setting cooling comprises gas mist covering setting cooling on the weld toes and the bending region, the spray covering area is 1.5-5 times the heat-affected zone of the weld toe laser molten pool, the equivalent cooling rate is 50-200 ℃ / s, the thickness temperature difference is controlled to be less than or equal to 40-60 ℃, and the temperature difference is automatically reduced and the spray flow is increased when the temperature difference exceeds the limit.

2. The method of claim 1, wherein the method is a laser roll forming method for manufacturing a star-shaped high-strength steel part for a vehicle. In the step S10, the plate and surface preparation comprises: The plate is made of high-strength steel, the yield strength is greater than or equal to 1500 MPa, the tensile strength is 1600-1800 MPa, and the elongation is greater than or equal to 8%; the thickness of the plate is 1-5 mm, and the thickness deviation is less than or equal to ±0.05 mm; The surface preparation comprises flattening treatment: a two-roller or four-roller flattening machine is used to flatten the plate, the flattening pressure is set to 5-8 MPa according to the thickness of the plate, and the plate flatness is ensured to be less than or equal to 0.2 mm / m; the roller surface roughness is less than or equal to 0.8 μm; The surface preparation comprises cleaning and drying: a spray cleaning machine is used to remove impurities such as oil stains and oxide scales on the surface of the plate, an alkaline cleaning agent with a concentration of 5-8% is used, the cleaning temperature is 40-60 ℃, and the cleaning time is 2-3 minutes; then the plate is dried in a hot air drying oven at 80-120 ℃ for 1-2 minutes, and the water content on the surface of the plate is ensured to be less than or equal to 0.1%; The surface preparation comprises burr detection: a laser thickness gauge is used to detect the edge burr of the plate, the detection accuracy is ±0.001 mm, and the burr height is ensured to be less than or equal to 0.1 mm; if the burr exceeds the standard, a grinding machine with a grain size of 120-180 mesh is used for trimming, and the edge roughness after trimming is less than or equal to 1.6 μm.

3. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel part for a vehicle by laser roll forming. In the step S10, the power-on self-test includes: master control and servo system detection, laser head detection, spray system detection, sensor calibration and alarm system test; The master control and servo system detection includes: starting the master PLC, establishing communication with the servo system of the robot, detecting that the communication delay is less than or equal to 10 ms; checking the servo motor current and speed through the PLC diagnosis interface, ensuring that the current fluctuation is ≤±5% and the speed deviation is ≤±1 rpm; The laser head detection includes: starting the fiber laser, performing power stability test, setting the power to 1000W-5000W, the interval power is 1000W, each power point is kept for 5 minutes, detecting that the power fluctuation is ≤±2%; at the same time, checking the coaxiality of the laser light path, detecting through the laser collimator, ensuring that the light path deviation is ≤0.05mm / m; The spray system detection includes: starting the gas mist cooling system, checking the flow of each nozzle, the flow is set to 5-15L / h; adjusting the flow according to the plate thickness, the flow corresponding to the plate thickness of 1-2mm is 5-10L / h, the flow corresponding to the plate thickness of 3-5mm is 10-15L / h; the flow error is ≤±5%; at the same time, checking the spray uniformity, using filter paper test, the spray coverage area deviation is ≤±10%; The sensor calibration includes: temperature precision calibration of the temperature measurement camera, using a standard blackbody furnace with a temperature range of 500-1000℃, the calibration accuracy is ±2℃; range calibration of the force sensor, the range is 0-50kN, the accuracy is ±0.1%; linearity calibration of the displacement sensor, the linearity is ±0.005mm; The alarm system test includes: simulating equipment abnormalities, checking whether the audible and visual alarm system is normally triggered, the alarm response time is ≤100ms.

4. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel part for a vehicle by laser roll forming. In the step S10, the tool and zero calibration includes: standard shape block preparation, roll head zero calibration, roll gap calibration, centering calibration and reference code storage; The standard shape block preparation includes: selecting a standard shape block made of 45 steel with a hardness of HRC28-32, the size of which is consistent with the cross section of the to-be-formed square tube, the size accuracy is ±0.005mm, and the surface roughness Ra is ≤0.8μm; three reference points are arranged on the standard shape block for laser positioning; The roll head zero calibration includes: fixing the standard shape block on the workbench, and adhering the roll head made of WC-Co with a hardness of HRC60-65 to the surface of the standard shape block by the robot, recording the coordinates of the roll head in X, Y and Z directions, and setting them as zero; repeating the calibration for 3 times to ensure that the repeated positioning accuracy is ±0.01mm; the roll wheel diameter of the roll head is set to 50-100mm according to the plate thickness; the roll wheel diameter of the roll head corresponding to the plate thickness of 1-2mm is 50-60mm, and the roll wheel diameter of the roll head corresponding to the plate thickness of 3-5mm is 80-100mm, the roll wheel width of the roll head is 2-3mm larger than the plate width; The roll gap calibration comprises: setting the roll gap according to the plate thickness, the roll gap value being 0.05-0.1 mm larger than the plate thickness; detecting the roll gap by means of a feeler gauge with an accuracy of ±0.001 mm, and ensuring that the roll gap deviation is ≤±0.01 mm; The centering calibration comprises: detecting the centering of the plate conveying path and the rolling head by means of a laser centering instrument, adjusting the position of the worktable so that the center of the plate and the center of the rolling head have a deviation of ≤0.05 mm, and recording the worktable coordinates as a reference for subsequent forming after centering; The reference code storage comprises: storing reference data such as zero-position coordinates, roll gap parameters and centering coordinates to the encrypted storage unit of the PLC; and simultaneously generating a calibration report, recording the calibration time, the operator and the equipment state; In the step S10, the robot TCP calibration comprises: laser focal point calibration, nozzle coaxiality calibration and TCP repeatability testing; The laser focal point calibration comprises: adjusting the posture of the robot so that the laser focal point falls in the center of the test card by means of a laser focal point test card, and recording the focal point coordinates; and ensuring that the focal point diameter deviation is ≤±0.1 mm by adjusting the position of the focusing mirror with a focal length of 150-200 mm; The nozzle coaxiality calibration comprises: installing a brass nozzle with an inner diameter of 2-5 mm at the end of the laser head, detecting the coaxiality of the nozzle center and the laser focal point by means of a coaxiality tester, and ensuring that the coaxiality is ≤0.05 mm; if the coaxiality is out of tolerance, adjusting the nozzle fixing bolt until the requirement is met; The TCP repeatability testing comprises: moving the laser head and the rolling head in the working space by the robot to 5 different positions, stopping at each position and recording the TCP coordinates, calculating the repeatability, and ensuring that the repeatability is ±0.02 mm; the calibration frequency is set to be once every 8 hours, and if the equipment is stopped for more than 2 hours, the calibration is performed again.

5. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel part for a vehicle by laser roll forming. In the step S20, before the plate is bent and formed by the robot, preset process parameters are loaded according to the plate material and cross-sectional size, the process parameters comprising laser parameters, rolling parameters and temperature control parameters; The laser parameters comprise laser power, spot type, line speed and predetermined distance; the laser power is 1500 W-2500 W; the spot type is a rectangular spot with a size of 2 mm×5 mm or a wobbling spot, the wobbling amplitude of the wobbling spot being 1-3 mm and the frequency being 50-200 Hz; the line speed is 300-800 mm / min; and the predetermined distance between the laser head and the rolling head is 5-15 mm; The rolling parameters comprise pass number, rolling force and rolling speed; the pass number is determined according to the total bending angle and the maximum bending angle per pass; the rolling force is 8-15 kN; and the rolling speed is synchronized with the laser line speed, being 300-800 mm / min; The temperature control parameters include a target temperature window, a temperature fluctuation threshold and a compensation strategy, the target temperature window is 600-800℃, the temperature fluctuation threshold is ±10℃ or ±15℃, and the compensation strategy includes: when the temperature is lower than the target lower limit, increasing the laser power by 5%-10% or reducing the line speed by 10%-20%; when the temperature is higher than the target upper limit, reducing the laser power by 5%-10% or increasing the line speed by 10%-20%.

6. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel automobile part based on laser roll forming. In the step S20, before the plate is bent and formed by using the robot, the step further includes: Conducting plate positioning and fixing plate conveying; the pretreated plate is conveyed to the workbench by a servo feeder with an accuracy of ±0.05mm, and the feeding length is set according to the unfolded length of the pipe; Conducting positioning and clamping in plate positioning and fixing; the plate is fixed on the workbench by using a pneumatic gripper with a clamping force of 5-10kN, and a rubber pad with a thickness of 2mm and a hardness of Shore A60 is pasted at the contact part between the gripper and the plate; the positioning reference adopts two adjacent edges of the plate, and the positioning pin with an accuracy of ±0.005mm is used to ensure that the position deviation of the plate is ≤±0.05mm; Conducting visual positioning confirmation in plate positioning and fixing; start the industrial camera, take pictures of the plate positioning state, compare with the preset positioning template, calculate the position deviation, if the deviation exceeds ±0.05mm, automatically adjust the position of the servo feeder until the requirement is met.

7. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel automobile part based on laser roll forming. In the step S20, the plate is bent and formed by using the robot, including a first bending section, a second bending section, a third bending section, a fourth bending section and a fifth bending section; The first bending section is a vertical upward bending section in the closed rectangular tube forming stage; the robot drives the laser head to irradiate the plate at the preset bending line, and the laser spot covers a range of 5-10mm beyond the bending line; at the same time, the rolling head moves with the laser head to apply rolling pressure to the heated plate, realizing vertical upward bending, and the bending height is consistent with the short side of the pipe; after each bending, the temperature camera detects the bending zone temperature in real time, and if the temperature is lower than the target value, the laser power is automatically increased by 5%; The second bending section is a horizontal inward bending section in the closed rectangular tube forming stage; after the first bending section is completed, the robot adjusts the posture, the laser head and the rolling head are turned to the horizontal direction at the same time, and the plate is bent horizontally inward, and the bending length is consistent with 1 / 2 of the long side of the pipe; during the horizontal bending process, the displacement sensor detects the bending length to ensure that the length deviation is ≤±0.1mm; at the same time, the guide wheel with a lateral pressure of 1-3kN closely contacts the side surface of the plate to prevent the plate from turning outward; The third bending section is a section of vertical downward bending in the closed rectangular tube forming stage; after the second bending section is completed, the robot adjusts the posture again, the laser head and the roll head are turned to the vertical downward direction, the plate is vertically downward bent, the bending depth is consistent with the vertical upward bending height, the second end of the plate contacts the upper surface of the unbent plate, and a closed rectangular tube is formed; at this time, the contact position is pressed by a robot follow-up pressure block with a pressure of 3-5kN to ensure that the gap is ≤0.1mm; the cross-sectional size tolerance of the closed rectangular tube is controlled within ±0.1mm, the corner R / t is 2-3, and the thinning rate is ≤8%; The fourth bending section is a section of vertical upward bending in the C-shaped tube forming stage; after the closed rectangular tube is formed, the robot drives the laser head and the roll head to move to the unbent area on the other side of the plate, preheats the preset bending line by laser, and then vertically upward bends, the bending height is consistent with the short side of the chevron tube; in the process, the roll pressure is monitored by a force sensor, and if the roll pressure exceeds 10% of the set value, the bending speed is automatically reduced to avoid plate rupture; The fifth bending section is a section of horizontal inward bending in the C-shaped tube forming stage; after the fourth bending section is completed, the laser head and the roll head are turned to the horizontal direction, the plate is horizontally inward bent, the bending length is consistent with 1 / 2 of the long side of the chevron tube, and a C-shaped tube is formed; the first end contacts the outer surface of the closed rectangular tube, the contact gap is detected by a vision camera to ensure that the contact gap is ≤0.1mm; if the gap is too large, adjust the position of the roll head to increase 1-2 times of fine bending.

8. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel part for a vehicle by laser roll forming. In the step S20, after the plate is bent and formed by the robot, the forming quality is detected and the forming defect is controlled; the forming defect control includes wrinkle control, edge crack control and springback out-of-tolerance control; Wrinkle control is performed in the area with a bending radius ≤50mm, including increasing the follow-up pressure block pressure to 5kN, reducing the laser spot swing amplitude to 1mm, and reducing the bending angle of each pass to 5°; the wrinkle occurrence rate is controlled to be less than 1%; Edge crack control is performed in the cold work hardening zone of AHSS, including increasing the laser preheating temperature to 800℃, increasing the pass number to 15, reducing the bending angle of each pass to 6°, pre-softening the plate edge by laser local heating to 700℃ for 10 seconds; the edge crack occurrence rate is controlled to be less than 3%; Springback out-of-tolerance control includes increasing the target temperature by 20-50℃, increasing the roll pressure by 10%-15%, increasing 1-2 times of correction bending after forming, and 1°-2° per pass; the springback angle is controlled to be 0.3°-0.8°.

9. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel automobile part based on laser roll forming, characterized by, In the step S30: Clean the interface before welding: use high-pressure air with a pressure of 0.5-0.8MPa to blow off dust and metal debris at the interface; if there is an oxide skin at the interface, use a steel wire brush with a particle size of 120# to polish, and the surface roughness Ra after polishing is ≤1.6μm; Preforming and temporary occlusion at the interface before welding: at the interface of the first end and the closed rectangular tube, a pressure of 3-5 kN is applied by a robot pressure jaw to form a temporary occlusion, and the occlusion length is 3-5 mm; at the same time, a guide slope of 15-30° is processed at the interface, and a fitting gap of 0.1-0.5 mm is reserved to accommodate the size deviation of the sheet metal; Welding parameter preset before welding: laser power 3000-4000 W, welding wire ER100S-G with a diameter of 1.2 mm, wire feeding speed 8-12 m / min, welding speed 300-500 mm / min, defocusing distance 2-3 mm, and protective gas Ar+2%O2 with a flow rate of 15-20 L / h; Arc striking and arc extinguishing treatment during welding: when striking the arc, the laser power gradually increases from 50% to the set value within 0.5-1 second to avoid instant high temperature causing the welding wire to burn out; when extinguishing the arc, the laser power gradually decreases to 50% within 0.5-1 second, and at the same time, the wire feeding speed is reduced synchronously to avoid the formation of arc pits; Monitoring during welding: real-time monitoring of weld formation by an industrial camera with a frame rate of 30 fps, detection of weld toe transition radius and weld reinforcement; if the weld toe transition radius is <0.5 mm, increase the protective gas flow rate by 5%; if the weld reinforcement is >1.5 mm, reduce the welding speed by 10%; at the same time, a temperature measurement camera detects the HAZ temperature to ensure that the peak temperature of the HAZ is ≤1000℃ or ≤600℃ to avoid coarse grains; If the sheet metal thickness is >3 mm during welding, multi-pass welding (2-3 passes) is adopted, the first pass fills 1 / 2 of the interface depth, and the second pass fills to the level of the interface; the interval between multi-pass welding is 2-3 minutes, and the HAZ temperature is reduced to below 300℃ to avoid heat accumulation causing deformation; Appearance detection in weld quality detection after welding: after welding, the weld appearance is detected by visual inspection and 10 times magnification, and there are no defects such as cracks, pores, and incomplete fusion; the weld reinforcement is 0.5-1.5 mm, the weld width deviation is ≤±0.5 mm, and the weld toe transition radius is ≥0.5 mm; Non-destructive testing in weld quality detection after welding: non-destructive testing of the weld is carried out using an ultrasonic flaw detector, the detection frequency is 5 MHz, and the probe angle is 45° to ensure that the internal porosity of the weld is ≤0.5%, and the incomplete fusion length is ≤1 mm; for high-strength steel welds, additional magnetic particle testing is carried out to detect surface cracks; Mechanical property sampling detection in weld quality detection after welding: randomly select 3 workpieces from each batch for weld tensile testing, and the weld tensile strength should not be less than 90% of the base metal; at the same time, the bending test is carried out with a bending angle of 180° and a bending core radius of 2 times the plate thickness, and the weld has no cracks.

10. The method of claim 1, wherein the method is a method of manufacturing a star-shaped high-strength steel automobile part based on laser roll forming. In the step S40: Parameter setting of aerosol setting and cooling: equivalent cooling rate 150-200℃ / s, spray coverage area is 2-3 times the weld toe HAZ, and cooling medium is deionized water+5% anti-rust agent; Aerosol setting and cooling process control: After welding, the robot moves the spray nozzle to the weld area, and the distance between the spray nozzle and the weld is set to 10-20 mm; the temperature of the weld is detected in real time by a temperature measurement camera, and when the temperature drops from the peak to 600℃, the spray cooling is started; during the cooling process, the thickness is controlled to be ≤40-60℃, and if the temperature difference exceeds the limit, the line speed is automatically reduced by 20% and the spray flow is increased by 30%; After cooling, the microstructure is detected: after cooling, the microstructure of the weld is observed by metallographic microscope, the high-strength steel weld is martensite microstructure with content ≥90%, and the grain size is ≤10μm; the aluminum alloy weld is mainly α-Al solid solution, and there is no obvious precipitate phase; Calibration pressure setting: according to the section size of the day pipe, the calibration pressure is set, the calibration pressure of 110mm×34mm section is 8-10kN, and the calibration pressure of 120mm×40mm section is 10-12kN; the calibration pressure is monitored in real time by force sensor, and the deviation is ≤±0.5kN; Straightening process includes: fixing the cooled day pipe on the calibration tool, and calibrating the section as a whole by hydraulic calibration head with stroke accuracy ±0.01mm, focusing on the middle strong rib and the corner; after calibration, the section size is detected by laser profiler to ensure that the size tolerance is ±0.1mm; then straighten the straightness, apply 2-5kN pressure through straightening rollers with a spacing of 500-1000mm, and the straightness after straightening is ≤0.5mm / m.

Images