Rapid forming method for bent pipe of motorcycle exhaust tail section

Abstract

The invention discloses a rapid forming method for a motorcycle exhaust tail section bent pipe. According to the method, the physical constraint of a traditional mechanical mold is broken through through the electromagnetic field auxiliary bending technology, the metal pipe fitting is guided to be automatically formed through the dynamic regulation and control magnetic field, the mold development period and cost consumption are avoided, and the continuous curvature transition effect which is difficult to achieve through a traditional technology is achieved. A closed-loop feedback system corrects a forming track in real time and is matched with an intelligent temperature control and stress relief mechanism to ensure that the stable extension characteristic of the material is maintained in the high-speed deformation process; the surface quality of the airflow channel is optimized while residual stress is eliminated through high-frequency vibration treatment, and the airtightness and the noise reduction effect of the exhaust system are remarkably improved in cooperation with precise matching of the sealing face in the finish machining stage. According to the method, through deep fusion of accurate regulation and control of a physical field and digital manufacturing, a novel manufacturing normal form with quick response and controllable quality is provided for a customized motorcycle exhaust system.

Description

Technical Field

[0001] The present invention belongs to the technical field of motorcycle exhaust production, and specifically relates to a rapid prototyping method for the bent pipe of the motorcycle exhaust tail section. Background Art

[0002] The bent pipe of the motorcycle exhaust tail section is a key component in the motorcycle exhaust system. It is located behind the muffler, responsible for guiding the treated exhaust gas to the rear and affecting the exhaust back pressure and sound. The design of its bent pipe needs to consider the smoothness of the air flow, aesthetics and the matching degree with the vehicle body. Traditionally, the production of the tail section bent pipe is carried out manually or by a special pipe bender, and the process is relatively cumbersome and time-consuming. The rapid prototyping technology for the bent pipe of the motorcycle exhaust tail section is an advanced manufacturing method. Through equipment such as numerical control pipe benders and hydraulic pipe benders, combined with computer-aided design (CAD) and computer-aided manufacturing (CAM) technologies, it realizes the efficient and precise forming of the bent pipe. This technology can quickly set the bent pipe parameters, such as bending angle, bending radius, etc., and complete the bent pipe process through automatic control, greatly improving the production efficiency and bent pipe accuracy, reducing material waste and labor costs. The rapid prototyping technology is also easy to realize the processing of complex bent pipe shapes, meeting the different vehicle models and performance requirements, and promoting the modernization process of motorcycle exhaust system manufacturing.

[0003] However, the existing technology is prone to cause material stress concentration and surface damage during the traditional bending process. At the same time, the residual stress is not completely eliminated, resulting in poor fatigue resistance of the product. The subsequent processing procedures are cumbersome and it is difficult to meet the requirements of coating bonding strength and airtightness, seriously restricting the development efficiency and performance of customized exhaust systems. Summary of the Invention

[0004] The purpose of the present invention is to provide a rapid prototyping method for the bent pipe of the motorcycle exhaust tail section in order to solve the above-mentioned problems.

[0005] The technical scheme adopted by the present invention is as follows: A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section, the method includes the following steps:

[0006] S1: Reverse obtain the spatial coordinates of the connection end face of the original vehicle exhaust pipe by using three-dimensional laser scanning technology;

[0007] S2: Generate a continuous curvature transition curve of the center line of the target bent pipe based on parametric modeling software;

[0008] S3: Decompose the bent pipe structure into straight pipe segments and bending segments for segmented pretreatment;

[0009] S4: Develop a flexible silicone inner lining mold system and pre-install a metal memory alloy support framework;

[0010] S5: Apply electromagnetic field-assisted bending technology to realize the magnetic control forming of the pipe without a mold;

[0011] S6: Monitor the material elongation rate distribution in the bending area in real time through infrared thermal imaging;

[0012] S7: Use a high-frequency vibration stress relief device for deformation self-correction;

[0013] S8: Implement the synchronous thermal diffusion bonding process of nano-ceramic coating and the pipe body;

[0014] S9: Perform multi-axis linkage finish machining to complete the flange end face and muffler interface matching.

[0015] In a preferred embodiment, in the step S1, a blue laser scanner is used for high-precision data acquisition. The working distance of the scanning head is set to 300 ± 5 mm, the line laser width is adjusted to 0.08 mm, and the scanning speed is controlled within 1.2 m / s. During scanning, the ambient temperature needs to be maintained at 20 ± 2 °C and the humidity is below 60%. The point cloud data accuracy is ensured to reach ±0.03 mm through multi-view stitching. For the exhaust pipe end face features, a local encryption scanning mode is set, and the point cloud density in the feature area is increased to 200 points / mm 2 , and the industrial camera is synchronously triggered to capture texture information to generate a complete three-dimensional model including spatial coordinates and surface roughness.

[0016] In a preferred embodiment, in the step S2, a NURBS curve model is constructed based on the Alias AutoStudio software. The curvature continuous transition condition is set to the G3 level, and the adjacent node spacing does not exceed 5 mm. The centerline curvature distribution is optimized through the genetic algorithm. The constraint conditions include 1.5 times the pipe diameter of the minimum bending radius and the tangent angle deviation between adjacent bending segments is less than 2°. After inputting material parameters such as the elastic modulus of the pipe material 210 GPa and Poisson's ratio 0.3, the theoretical forming path is generated and then the dynamic simulation verification is performed, and the maximum forming stress is limited to less than 75% of the material yield strength.

[0017] In a preferred embodiment, in the step S3, a 4 kW fiber laser cutting machine is used to cut the stainless steel pipe blank. The cutting speed is set to 12 m / min, the focus position offset is -0.5 mm, and the nitrogen auxiliary air pressure is 0.8 MPa. The reserved length tolerance of the straight pipe section is ±0.1 mm, and a 10 mm process margin is reserved for the bending section. After cutting, a 240-mesh sanding machine is used to deburr the cut, the surface roughness Ra ≤ 1.6 μm, and magnetic particle flaw detection is used to detect the cut area to ensure that there are no micro-crack defects.

[0018] In a preferred embodiment, in step S4, the mold silicone is an addition-type liquid silicone rubber with a Shore hardness of 35A. The A and B components are mixed in a 10:1 ratio, vacuum-degassing, injected into a 3D-printed ABS mold frame, and cured at 80°C for 45 minutes. The shape memory alloy skeleton is made of NiTiNol wire with a diameter of 1.2 mm and an austenite transition temperature set at 90°C. It is pre-bent and inserted into the silicone mold cavity. During assembly, the skeleton is pre-strained by 8%, and the shape memory effect is activated by resistance heating to 120°C, ensuring that the mold cavity and the target bend shape are within 0.15 mm of each other.

[0019] In a preferred embodiment, in step S5, the number of turns of the coil of the annular array electromagnetic generating device is controlled to be 120 to 180 turns, the operating frequency is set to an adjustable range of 2.5-3.8 kHz, and the single pulse current intensity is maintained in the range of 800-1200 A;

[0020] The specific steps include: first, generating a magnetic field intensity gradient map driven by 3D modeling data, and establishing an axial magnetic induction intensity gradient field of 0.8-1.6T / m along the centerline of the target bend. The 316L stainless steel guide core rod pre-installed inside the pipe generates induced eddy currents in the alternating magnetic field, and its current density must reach 45-65A / mm 2 To form an effective Lorentz force.

[0021] During the forming process, a closed-loop feedback system dynamically adjusts magnetic field parameters. Hall sensors collect real-time magnetic flux data on the tube surface, and the magnetic field distribution model is updated every 50 milliseconds in conjunction with finite element simulation software. When the actual bending curvature deviates from the theoretical value by more than 0.15 rad / m, the system automatically increases the magnetic field intensity compensation value in the corresponding area. The compensation amount increases the magnetic field gradient intensity by 1.2% for every 0.01 rad deviation. Key control parameters include an adaptive matching algorithm for the tube's yield strength. This algorithm dynamically adjusts the Lorentz force output based on the material's real-time yield strength, σs, ensuring that the force vector direction in the formula F = J × B × t always remains within ±5° of the preset trajectory tangent direction. A liquid nitrogen cooling system is simultaneously activated to stabilize the bending area temperature between 120-150°C to prevent material recrystallization.

[0022] This technology eliminates mold friction losses through contactless magnetic forming. It can handle complex curved surfaces with a minimum bend radius of up to 1.2 times the pipe diameter, achieving a forming accuracy of ±0.25mm / m, more than three times the efficiency of traditional mechanical bending processes. After final forming, demagnetization is required to reduce the residual magnetic field strength of the pipe to below the standard of 5 gauss.

[0023] In a preferred embodiment, in step S6, an FLIR X8580sc infrared thermal imager is used to monitor the bending area in real time, with a spectral response range of 3.6 - 4.1 μm and a thermal sensitivity of 0.03 °C. The monitoring frame rate is set at 500 Hz, and a graphene coating with a thickness of 0.05 mm is sprayed on the surface of the pipe to increase the emissivity to 0.95. Through the temperature-strain coupling algorithm, the gray value of the thermal image is converted into a material elongation distribution map. When the local temperature exceeds 450 °C or the elongation difference is greater than 15%, an emergency stop is triggered to avoid excessive necking of the material.

[0024] In a preferred embodiment, in step S7, a 20 kHz ultrasonic vibration device is configured. The output amplitude of the transducer is set at 12 μm, and the vibration direction forms a 45° angle with the axis of the pipe. The vibration head moves along the surface of the bent pipe at a speed of 0.8 m / min, applying a dynamic excitation force in the range of 50 - 150 N. The resonance frequency offset is monitored in real time by an impedance analyzer, and when the offset exceeds 5 Hz, the output power is automatically adjusted to ensure that the residual stress elimination rate is ≥ 85%. The processing time is controlled in grades according to the curvature radius of the bent pipe. The vibration continues for 90 seconds in the area where R ≤ 50 mm, and for 60 seconds in the area where R > 50 mm.

[0025] In a preferred embodiment, in step S8, an atmospheric plasma spraying process is used to deposit an Al2O3-TiO2 composite ceramic layer on the surface of the bent pipe. The powder particle size distribution is 15 - 45 μm, and the powder feeding rate is 35 g / min. The plasma arc current is set at 500 A, the voltage is 65 V, and the argon / hydrogen flow ratio is 9:1. When spraying, the pipe body rotates at a speed of 20 rpm, and the axial moving speed is 8 mm / s. At the same time, the pipe body is inductively heated to 620 ± 10 °C to produce a diffusion bonding layer of 3 - 5 μm between the ceramic layer and the substrate. The final coating thickness is controlled at 80 ± 5 μm, the porosity is less than 2%, and the surface hardness is ≥ 1200 HV0.3.

[0026] In a preferred embodiment, in step S9, a five-axis CNC machine tool is used to machine the flange end face. The spindle speed is 4000 rpm, the feed speed is 800 mm / min, and the diameter of the cemented carbide milling cutter is 16 mm. The clamping error is compensated in real time by an online laser tool setter, and the axial positioning accuracy is ±0.005 mm. The muffler interface adopts a turning composite process. The rough turning cutting depth is 0.5 mm, the finish turning allowance is 0.05 mm, and the surface turning texture direction is consistent with the air flow direction. After machining, a helium mass spectrometer leak detector is used to test the sealing surface, and the leakage rate requirement is ≤ 1×10^-6 Pa·m 3 / s to ensure that the assembly airtightness meets the standard.

[0027] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

[0028] 1. In the present invention, through the innovative application of non-contact magnetic control forming technology, the manufacturing efficiency and precision of complex bent pipe structures are significantly improved. The electromagnetic field-assisted bending technology breaks through the physical constraints of traditional mechanical molds and uses dynamic magnetic field regulation to guide the self-forming of metal pipe fittings. This not only avoids the mold development cycle and cost consumption but also achieves a continuous curvature transition effect that is difficult to achieve by traditional processes. The closed-loop feedback system corrects the forming trajectory in real time and, in conjunction with the intelligent temperature control and stress elimination mechanism, ensures that the material maintains stable ductility characteristics during high-speed deformation, taking into account both geometric accuracy and mechanical properties. This flexible production method can directly process the original pipe blank and complete multi-angle spatial bending in a single forming, significantly shortening the process flow chain.

[0029] 2. In the present invention, the metallurgical bonding between the uniform microstructure formed in the magnetic control forming stage and the subsequent nano-ceramic coating effectively enhances the high-temperature corrosion resistance of the pipe body. The high-frequency vibration treatment eliminates residual stress while optimizing the surface quality of the air flow channel, and in conjunction with the precise matching of the sealing surface in the finishing stage, significantly improves the airtightness and noise reduction effect of the exhaust system. This method provides a new manufacturing paradigm with both rapid response and controllable quality for customized motorcycle exhaust systems through the precise regulation of physical fields and the deep integration of digital manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process principle of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Refer to Figure 1 ,

[0033] A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section, the method comprising the following steps:

[0034] S1: Use three-dimensional laser scanning technology to reversely obtain the spatial coordinates of the connection end face of the original vehicle exhaust pipe;

[0035] S2: Generate a continuous curvature transition curve of the center line of the target bent pipe based on parametric modeling software;

[0036] S3: Decompose the bent pipe structure into straight pipe sections and bending sections for segmented pretreatment;

[0037] S4: Develop a flexible silicone inner lining mold system and pre-install a metal memory alloy support framework;

[0038] S5: Apply electromagnetic field-assisted bending technology to achieve magnetic control forming of the pipe without a mold;

[0039] S6: Monitor the material elongation rate distribution in the bending area in real time through infrared thermal imaging;

[0040] S7: Use a high-frequency vibration stress relief device for deformation self-correction;

[0041] S8: Implement the process of synchronous thermal diffusion bonding of nano-ceramic coating and the pipe body;

[0042] S9: Perform multi-axis linkage finish machining to complete the matching of the flange end face and the muffler interface.

[0043] In step S1, a blue laser scanner is used for high-precision data acquisition. The working distance of the scanning head is set to 300 ± 5 mm, the width of the line laser is adjusted to 0.08 mm, and the scanning speed is controlled within 1.2 m / s. During scanning, the ambient temperature needs to be maintained at 20 ± 2 °C, and the humidity is below 60%. The accuracy of the point cloud data is ensured to reach ±0.03 mm through multi-view stitching. For the exhaust pipe end face features, a local encryption scanning mode is set, and the point cloud density in the feature area is increased to 200 points / mm 2 , and the industrial camera is synchronously triggered to capture texture information to generate a complete three-dimensional model containing spatial coordinates and surface roughness.

[0044] In step S2, a NURBS curve model is constructed based on the Alias AutoStudio software. The curvature continuous transition condition is set to the G3 level, and the distance between adjacent nodes does not exceed 5 mm. The curvature distribution of the center line is optimized through the genetic algorithm. The constraint conditions include 1.5 times the pipe diameter of the minimum bending radius and the tangent angle deviation between adjacent bending segments less than 2°. After inputting material parameters such as the elastic modulus of the pipe material 210 GPa and Poisson's ratio 0.3, the theoretical forming path is generated and then the dynamic simulation verification is performed, and the maximum forming stress is limited to less than 75% of the material yield strength.

[0045] In step S3, a 4 kW fiber laser cutting machine is used to cut the stainless steel pipe blank. The cutting speed is set to 12 m / min, the focus position offset is -0.5 mm, and the nitrogen auxiliary air pressure is 0.8 MPa. The tolerance of the reserved length of the straight pipe section is ±0.1 mm, and a 10 mm process margin is reserved for the bending section. After cutting, a 240-mesh sanding machine is used to deburr the cut, the surface roughness Ra ≤ 1.6 μm, and magnetic particle flaw detection is used to detect the cut area to ensure no micro-crack defects.

[0046] In step S4, the mold silicone is made of addition-type liquid silicone with a Shore hardness of 35A. The A and B components are mixed in a 10:1 ratio, vacuum-degassing, injected into a 3D-printed ABS mold frame, and cured at 80°C for 45 minutes. The shape memory alloy skeleton is made of NiTiNol wire with a diameter of 1.2mm and an austenite transition temperature set at 90°C. It is pre-bent and inserted into the silicone mold cavity. During assembly, the skeleton is pre-strained by 8%, and the shape memory effect is activated by resistance heating to 120°C, ensuring that the mold cavity and the target bend shape are within 0.15mm of each other.

[0047] In step S5, the number of turns of the coil of the annular array electromagnetic generator is controlled to be 120 to 180 turns, the operating frequency is set to an adjustable range of 2.5-3.8 kHz, and the single pulse current intensity is maintained in the range of 800-1200 A;

[0048] The specific steps include: first, generating a magnetic field intensity gradient map driven by 3D modeling data, and establishing an axial magnetic induction intensity gradient field of 0.8-1.6T / m along the centerline of the target bend. The 316L stainless steel guide core rod pre-installed inside the pipe generates induced eddy currents in the alternating magnetic field, and its current density must reach 45-65A / mm 2 To form an effective Lorentz force.

[0049] During the forming process, a closed-loop feedback system dynamically adjusts magnetic field parameters. Hall sensors collect real-time magnetic flux data on the tube surface, and the magnetic field distribution model is updated every 50 milliseconds in conjunction with finite element simulation software. When the actual bending curvature deviates from the theoretical value by more than 0.15 rad / m, the system automatically increases the magnetic field intensity compensation value in the corresponding area. The compensation amount increases the magnetic field gradient intensity by 1.2% for every 0.01 rad deviation. Key control parameters include an adaptive matching algorithm for the tube's yield strength. This algorithm dynamically adjusts the Lorentz force output based on the material's real-time yield strength, σs, ensuring that the force vector direction in the formula F = J × B × t always remains within ±5° of the preset trajectory tangent direction. A liquid nitrogen cooling system is simultaneously activated to stabilize the bending area temperature between 120-150°C to prevent material recrystallization.

[0050] This technology eliminates mold friction loss through non-contact magnetic forming, can handle complex spatial curves with a minimum bending radius of 1.2 times the pipe diameter, and has a forming accuracy of ±0.25mm / m, which is more than 3 times more efficient than traditional mechanical bending processes. After the final forming, demagnetization treatment is required to reduce the residual magnetic field strength of the pipe to below the standard of 5 gauss.

[0051] In step S6, an FLIR X8580sc infrared thermal imager is used to monitor the bending area in real time. The spectral response range is 3.6 - 4.1 μm, and the thermal sensitivity is 0.03 °C. The monitoring frame rate is set at 500 Hz, and a graphene coating with a thickness of 0.05 mm is sprayed on the surface of the pipe to increase the emissivity to 0.95. Through the temperature-strain coupling algorithm, the gray value of the thermal image is converted into a material elongation distribution map. When the local temperature exceeds 450 °C or the elongation difference is greater than 15%, an emergency shutdown is triggered to avoid excessive necking of the material.

[0052] In step S7, a 20 kHz ultrasonic vibration device is configured. The output amplitude of the transducer is set at 12 μm, and the vibration direction forms a 45° angle with the axis of the pipe. The vibration head moves along the surface of the bent pipe at a speed of 0.8 m / min, and the dynamic excitation force applied ranges from 50 - 150 N. The impedance analyzer is used to monitor the resonance frequency offset in real time. When the offset exceeds 5 Hz, the output power is automatically adjusted to ensure that the residual stress elimination rate is ≥ 85%. The processing time is controlled by grading according to the bending radius of the pipe. The vibration lasts for 90 seconds in the area where R ≤ 50 mm, and 60 seconds in the area where R > 50 mm.

[0053] In step S8, the atmospheric plasma spraying process is adopted to deposit an Al2O3-TiO2 composite ceramic layer on the surface of the bent pipe. The powder particle size distribution is 15 - 45 μm, and the powder feeding rate is 35 g / min. The plasma arc current is set at 500 A, the voltage is 65 V, and the argon / hydrogen flow ratio is 9:1. During spraying, the pipe body rotates at a speed of 20 rpm, and the axial moving speed is 8 mm / s. At the same time, the pipe body is inductively heated to 620 ± 10 °C to produce a diffusion bonding layer of 3 - 5 μm between the ceramic layer and the substrate. The final coating thickness is controlled within 80 ± 5 μm, the porosity is less than 2%, and the surface hardness is ≥ 1200 HV0.3.

[0054] In step S9, a five-axis CNC machine tool is used to machine the flange end face. The spindle speed is 4000 rpm, the feed speed is 800 mm / min, and the diameter of the cemented carbide milling cutter is 16 mm. The online laser tool setter is used to compensate for the clamping error in real time, and the axial positioning accuracy is ±0.005 mm. The muffler interface adopts the turning composite process. The rough turning cutting depth is 0.5 mm, the finish turning allowance is 0.05 mm, and the surface turning texture direction is consistent with the air flow direction. After machining, a helium mass spectrometer leak detector is used to test the sealing surface, and the leakage rate requirement is ≤ 1×10^-6 Pa·m 3 / s to ensure that the assembly airtightness meets the standard.

[0055] It can be known from the above:

[0056] In the present invention, through the innovative application of non-contact magnetic control forming technology, the manufacturing efficiency and precision of complex bent pipe structures have been significantly improved. The electromagnetic field-assisted bending technology breaks through the physical constraints of traditional mechanical dies and uses dynamic magnetic field control to guide the self-forming of metal pipe fittings. This not only avoids the mold development cycle and cost consumption but also achieves a continuous curvature transition effect that is difficult to achieve with traditional processes. The closed-loop feedback system corrects the forming trajectory in real time and, in conjunction with the intelligent temperature control and stress relief mechanisms, ensures that the material maintains stable ductility characteristics during the high-speed deformation process, taking into account both geometric accuracy and mechanical properties. This flexible production method can directly process the original pipe blank and complete multi-angle spatial bending in a single forming, significantly shortening the process flow chain.

[0057] In the present invention, the metallurgical bonding between the uniform microstructure formed in the magnetic control forming stage and the subsequent nano-ceramic coating effectively enhances the high-temperature corrosion resistance of the pipe body; the high-frequency vibration treatment eliminates residual stress while optimizing the surface quality of the air flow channel, and in conjunction with the precise matching of the sealing surface in the finishing stage, significantly improves the airtightness and noise reduction effect of the exhaust system. This method provides a new manufacturing paradigm for customized motorcycle exhaust systems that combines rapid response and controllable quality through the precise control of physical fields and the deep integration of digital manufacturing.

[0058] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section, characterized in that: The method includes the following steps: S1: Reverse obtain the spatial coordinates of the connecting end face of the original vehicle exhaust pipe by using 3D laser scanning technology; S2: Generate a continuous curvature transition curve of the center line of the target elbow based on parametric modeling software; S3: Decompose the elbow structure into straight pipe segments and bending segments for segmented pretreatment; S4: Develop a flexible silicone inner lining mold system and pre-install a metal memory alloy support skeleton; S5: Apply electromagnetic field-assisted bending technology to achieve magnetic control forming of pipes without a mold; S6: Real-time monitor the material elongation rate distribution in the bending area through infrared thermal imaging; S7: Use a high-frequency vibration stress relief device for deformation self-correction; S8: Implement a process of synchronous thermal diffusion bonding of nano-ceramic coating and the pipe body; S9: Perform multi-axis linkage finish machining to complete the matching of the flange end face and the muffler interface.

2. A rapid prototyping method for the exhaust tail section elbow of a motorcycle as described in claim 1, characterized in that: In the step S1, a blue laser scanner is used for high-precision data acquisition. The working distance of the scanning head is set to 300 ± 50 mm, the width of the line laser is adjusted to 0.08 mm, and the scanning speed is controlled within 1.2 m / s. During scanning, the ambient temperature needs to be maintained at 20 ± 2 °C and the humidity is below 60%. The accuracy of the point cloud data is ensured to reach ±0.03 mm through multi-view stitching. For the end-face features of the exhaust pipe, a local encryption scanning mode is set, and the point cloud density in the feature area is increased to 200 points / mm 2 , and the industrial camera is synchronously triggered to capture texture information, generating a complete three-dimensional model containing spatial coordinates and surface roughness.

3. A rapid prototyping method for the exhaust tail pipe elbow of a motorcycle according to claim 1, characterized in that: In the step S2, build a NURBS curve model based on the Alias AutoStudio software, set the curvature continuous transition condition to the G3 level, and the adjacent node spacing does not exceed 5 mm; optimize the center line curvature distribution through the genetic algorithm, and the constraint conditions include a minimum bending radius of 1.5 times the pipe diameter and the tangent angle deviation between adjacent bending segments is less than 2°.

4. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section according to claim 1, characterized in that: In the step S3, use a 4kW fiber laser cutting machine to cut the stainless steel pipe blank, set the cutting speed to 12m / min, the focus position offset to -0.5mm, and the nitrogen auxiliary air pressure to 0.8MPa; the reserved length tolerance of the straight pipe segment is ±0.1mm, and a 10mm process margin is reserved for the bending segment; after cutting, use a 240-mesh sanding machine to deburr the cut, the surface roughness Ra≤1.6μm, and use magnetic particle flaw detection to detect the cut area to ensure no micro-crack defects.

5. A rapid prototyping method for the bent pipe at the tail section of a motorcycle exhaust, characterized in that: In the step S4, the mold silicone is a platinum-cured liquid silicone with a Shore hardness of 35A. The A and B components are mixed in a ratio of 10:1 and then degassed under vacuum, and injected into a 3D printed ABS mold frame and cured at 80°C for 45 minutes to form; the memory alloy skeleton uses NiTiNol wire with a diameter of 1.2mm, the austenite phase transformation temperature is set to 90°C, and after pre-bending and forming, it is embedded in the inner cavity of the silicone mold; when assembling, apply a pre-strain of 8% to the skeleton, heat it to 120°C with resistance to activate the shape memory effect, so that the error between the inner cavity of the mold and the outer shape of the target elbow is less than 0.15mm.

6. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section according to claim 1, characterized in that: In the step S5, the number of turns of the coil of the annular array electromagnetic generating device is controlled within 120 - 180 turns, the working frequency is set in the adjustable range of 2.5 - 3.8kHz, and the single-pulse current intensity is maintained in the range of 800 - 1200A; The specific steps include: first, generating a magnetic field intensity gradient map driven by 3D modeling data, establishing an axial magnetic induction intensity gradient field of 0.8-1.6T / m along the centerline of the target bend; the 316L stainless steel guide core rod preset inside the pipe generates induced eddy currents in the alternating magnetic field, and its current density needs to reach 45-65A / mm 2 To form an effective Lorentz force; During the forming process, a closed-loop feedback system is used to dynamically adjust the magnetic field parameters. The magnetic flux data on the surface of the pipe is collected in real time through a Hall sensor, and the magnetic field distribution model is updated every 50ms in cooperation with the finite element simulation software; when it is detected that the deviation between the actual bending curvature and the theoretical value exceeds 0.15rad / m, the system automatically enhances the magnetic field intensity compensation value in the corresponding area, and the compensation amount is increased by 1.2% magnetic field gradient intensity for every 0.01rad deviation.

7. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section according to claim 1, characterized in that: In the step S6, an FLIR X8580sc infrared thermal imager is used to monitor the bending area in real time, with a spectral response range of 3.6 - 4.1 μm and a thermal sensitivity of 0.03 °C; the monitoring frame rate is set at 500 Hz, and a graphene coating with a thickness of 0.05 mm is sprayed on the surface of the pipe to increase the emissivity to 0.95; through the temperature-strain coupling algorithm, the gray value of the thermal image is converted into a material elongation distribution map, and when the local temperature exceeds 450 °C or the elongation difference is greater than 15%, an emergency stop is triggered to avoid excessive necking of the material.

8. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section according to claim 1, characterized in that: In the step S7, a 20 kHz ultrasonic vibration device is configured, the output amplitude of the transducer is set at 12 μm, and the vibration direction forms a 45° angle with the axis of the pipe; the vibration head moves along the surface of the bent pipe at a speed of 0.8 m / min, applying a dynamic excitation force in the range of 50 - 150 N; the impedance analyzer is used to monitor the resonance frequency offset in real time, and when the offset exceeds 5 Hz, the output power is automatically adjusted to ensure that the residual stress elimination rate is ≥ 85%; the processing time is controlled by grading according to the bending radius of the pipe, vibrating for 90 seconds in the area where R ≤ 50 mm and vibrating for 60 seconds in the area where R > 50 mm.

9. A rapid prototyping method for the bent pipe of the motorcycle exhaust tail section according to claim 1, characterized in that: In the step S8, the atmospheric plasma spraying process is adopted to deposit an Al2O3-TiO2 composite ceramic layer on the surface of the bent pipe, with a powder particle size distribution of 15 - 45 μm and a powder feeding rate of 35 g / min; the plasma arc current is set at 500 A, the voltage is 65 V, and the argon / hydrogen flow ratio is 9:1; during spraying, the pipe body rotates at a speed of 20 rpm and moves axially at a speed of 8 mm / s, and the pipe body is synchronously induction heated to 620 ± 10 °C to produce a diffusion bonding layer of 3 - 5 μm between the ceramic layer and the substrate; the final coating thickness is controlled at 80 ± 5 μm, the porosity is less than 2%, and the surface hardness is ≥ 1200 HV0.

3.

10. A rapid prototyping method for the exhaust tail pipe elbow of a motorcycle according to claim 1, characterized in that: In the step S9, the flange end face is machined by a five-axis CNC machine tool, with the spindle speed of 4000 rpm, the feed rate of 800 mm / min, and the diameter of the carbide milling cutter of 16 mm; the clamping error is compensated in real time by an online laser tool setter, and the axial positioning accuracy is ±0.005 mm; the silencer interface adopts a turning composite process, with the rough turning cutting depth of 0.5 mm, the finish turning allowance of 0.05 mm, and the surface turning texture direction consistent with the air flow direction; after machining, a helium mass spectrometer leak detector is used to test the sealing surface, and the leakage rate requirement is ≤1×10^-6 Pa·m 3 / s to ensure that the assembly airtightness meets the standard.

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