Galvanometer laser seal welding method for titanium alloy tube plate

Abstract

The invention relates to the field of metal material welding, in particular to a galvanometer laser seal welding method for a titanium alloy tube plate, which comprises the following specific steps: S1, assembling the titanium alloy tube plate; s2, all the components and a welding area are placed in a flexible protection device; s3, inputting the CAD model of the tube plate into a master controller to generate a laser beam scanning path and a motion path of an industrial robot; s4, in the welding process, the welding seam tracking system and the molten pool monitoring system monitor the welding process, and the laser beam scanning path, the laser incident angle alpha and the laser process parameters are adjusted; and S5, the tube plate is taken out of the flexible protection device after being cooled. The CAD model is adopted to generate the laser beam scanning path, the welding seam tracking system and the molten pool monitoring system adjust the laser beam scanning path, the welding parameters and the incident angle alpha in real time, and the stability of the sealing process can be guaranteed while the sealing efficiency is greatly improved.

Description

Technical Field

[0001] The invention relates to the field of metal material welding, and in particular to a galvanometer laser sealing welding method for titanium alloy tube plates. Background Art

[0002] Shell and tube titanium alloy heat exchangers have very broad application prospects in the field of shipbuilding and marine engineering. They have excellent corrosion resistance, high strength, good thermal conductivity and lightweight characteristics. In addition, their design structure is compact and modular, which is easy to maintain and clean. They are suitable for heat exchange needs in a variety of harsh environments. They can not only improve work efficiency, but also significantly extend the service life of the equipment and reduce maintenance costs.

[0003] During the production process of shell and tube titanium alloy heat exchangers, the heat exchange tubes and tube sheets need to be sealed and welded. At present, the sealing and welding method of tube sheets is to use a special tungsten inert gas arc welding machine head to seal and weld one by one, which has low welding efficiency and is prone to defects such as incomplete penetration.

[0004] Publication number: CN112846506A proposes a high-speed galvanometer laser welding method, which can effectively improve the efficiency and quality of sealing. However, during this type of galvanometer laser welding, the laser moves rapidly perpendicular to the welding surface for welding. It is applied to the sealing of titanium alloy tube sheets. For extended tube sheets, the heat exchange tube needs to extend a certain distance from the end face of the tube sheet, which will interfere with the vertically captured laser and cannot complete the high-quality sealing of titanium alloy laser tube sheets. Publication number: CN105921872B proposes a method for electron beam sealing. The rotating table mainly rotates the rotating table to make the non-center tube to be welded only rotate around the center of the rotating table, but cannot rotate by itself, resulting in the welding of the electron gun with a fixed emission position and direction. The present invention uses an XY workbench located under the rotating table to solve the problem of the center of the tube to be welded being separated from the position to be welded. However, due to the limitation of the volume of the vacuum chamber, this method is not applicable to the sealing of large heat exchangers; and the welding efficiency is relatively limited due to the manual adjustment of the weld deviation by the CCD camera.

[0005] In order to improve the sealing efficiency and quality of titanium alloy tube sheets, it is urgent to design a new titanium alloy tube sheet sealing method to solve the problems of low sealing efficiency and low quality in the existing technology. Summary of the invention

[0006] In view of this, the present invention aims to propose a galvanometer laser welding method for titanium alloy tube sheets to solve the problems of low welding efficiency and low quality in the prior art.

[0007] Laser welding technology is a high-energy beam welding method that irradiates the surface of the workpiece with a focused laser to melt the material and achieve welding. Galvanometer laser welding uses the high-speed moving scanning lens inside the laser, combined with powerful graphics processing software and mobile devices, to achieve program-controlled instantaneous multi-point welding technology, achieve multi-point welding in the plane, and effectively improve the flexibility and efficiency of welding.

[0008] However, due to the laser scanning angle range of ±10° to ±30° in the prior art, the control angle movement range of the galvanometer laser by the moving device is difficult to cover the angle range of the tube sheet T-weld, and there are multiple parallel heat exchange tubes in the titanium alloy heat exchanger. The manufacturing errors of the heat exchange plates and heat exchange tubes themselves, the existence of adjacent heat exchange tubes, and the part of the heat exchange tube extending out of the plate make the environment around the tube sheet welding more complicated, limiting the incident angle of the laser and the improvement of the sealing efficiency.

[0009] In order to improve the sealing efficiency and quality of titanium alloy tube sheets, this application designs and develops a galvanometer laser sealing device, which imports the sealing trajectory through the CAD model, and adjusts the laser beam scanning path, welding parameters and incident angle α in time through the weld tracking system and molten pool monitoring system, which greatly improves the efficiency and quality of tube sheet sealing.

[0010] At the same time, for large titanium alloy shell and tube heat exchangers with a size of about 1000mm, the tube spacing is usually between 3 and 50mm, and the distance the tube extends out of the plate is generally 0 to 20mm, and some reach 50mm. In order to ensure that the titanium alloy does not react with oxygen during welding and to ensure the welding quality, the construction cost and maintenance cost of large vacuum chambers are high, making it difficult to promote their use in production. The present application creatively proposes a mobile device so that the weld profile collector and the molten pool profile collector can completely cover the weld, which can achieve all-round monitoring of the weld and the molten pool, improve welding quality and efficiency, and effectively ensure the stability and reliability of the welding process; creatively proposes a flexible protection device that does not affect the movement of the galvanometer laser head, the weld profile collector, and the molten pool profile collector, reduces the waste of shielding gas, avoids the heat exchange tube interfering with the protective atmosphere, improves the reliability and stability of the welding process, and helps to improve welding efficiency.

[0011] The technical solution of the present invention is achieved in this way: A galvanometer laser sealing welding method for titanium alloy tube sheet includes the following specific steps: S1: Assemble titanium alloy heat exchange tubes and plates; S2: placing the galvanometer laser head, the weld profile collector, the molten pool profile collector and the welding area in a flexible protective device; S3: The CAD model of the tube sheet is input into the main controller to generate the laser beam scanning path and the motion path of the industrial robot; S4: During the welding process, the weld tracking system collects information about the actual T-weld morphology and the surrounding environment of the weld, and then adjusts the laser beam scanning path and the laser incident angle α; the molten pool monitoring system collects the molten pool morphology during the sealing process, and then adjusts the laser process parameters; S5: After the sealing welding is completed, the tube sheet needs to be cooled before being removed from the flexible protective device.

[0012] Furthermore, in step S1, the titanium alloy tube sheet is assembled, and the verticality of the heat exchange tube and the plate is ensured during assembly. After the assembly is completed, the tube expansion method is used to achieve a close fit between the heat exchange tube and the plate.

[0013] Furthermore, in step S2, a moving device is provided on the galvanometer laser head, the moving device is connected to the weld profile collector and the molten pool profile collector, and the moving device is used to drive the weld profile collector and the molten pool profile collector to move circumferentially.

[0014] Furthermore, the moving device includes a fixed bracket, a circular track, a weld morphology collector rotating bracket and a molten pool morphology collector rotating bracket. The circular track is fixed to the galvanometer laser head via the fixed bracket. The weld morphology collector is connected to the circular track via the weld morphology collector rotating bracket. The molten pool morphology collector is connected to the circular track via the molten pool morphology collector rotating bracket. The weld morphology collector rotating bracket and the molten pool morphology collector rotating bracket can move circumferentially on the circular track.

[0015] Further, in step S2, the flexible protective device includes a flexible film and an adhesive tape, the flexible film is used to cover the welding area to create a protective atmosphere environment, the adhesive tape is used to seal the edge of the flexible film, and the flexible protective device has reserved air inlet holes and exhaust holes, the air inlet holes are used for argon filling, and the exhaust holes are used for air discharge. After the sealing is completed, the argon filling operation is performed to ensure that the oxygen content in the flexible protective device is not higher than 50ppm.

[0016] Further, in step S3, the laser incident angle is α, 0°<α< ; Where: B is the width of the hole bridge; H is the extended length of the heat exchange tube.

[0017] Furthermore, in step S3, during sealing, the galvanometer laser head is located on the central axis of the heat exchange tube. The galvanometer laser head is a variable focal length device with a focal length range of 275~325mm, a laser power of 0~6000W, a defocus amount of ~3~+3, and a welding speed of 0~15m / min.

[0018] Furthermore, in step S4, the weld morphology collector in the weld tracking system collects the actual values ​​of the actual T-type weld morphology, the heat exchange tube diameter Φ, the hole bridge gap B and the heat exchange tube extension length H, and feeds them back to the main controller through the weld image controller. The main controller compares the theoretical value transmitted by the CAD with the actual collected value, and adjusts the laser beam scanning path and the laser incident angle α according to the actual collected value.

[0019] Furthermore, in step S4, the molten pool morphology collector in the molten pool monitoring system collects the molten pool morphology during the sealing process, focusing on monitoring the spatter, keyholes, and unstable vortices in the molten pool, and generates a digital signal through the molten pool image controller and transmits it to the main controller in real time. The main controller adjusts the laser process parameters based on the comparison with the existing laser welding molten pool morphology database.

[0020] Furthermore, in step S5, after the sealing and welding is completed, the plate needs to be cooled to no higher than 100°C before being taken out from the flexible protective device.

[0021] Compared with the prior art, the galvanometer laser sealing welding method for titanium alloy tube sheet of the present invention has the following advantages: 1. The present invention provides a titanium alloy tube sheet galvanometer laser welding system consisting of a galvanometer laser welding system, a weld tracking system and a molten pool monitoring system. Compared with traditional tungsten inert argon arc welding, the welding efficiency of large titanium alloy heat exchangers can be significantly improved, the number of incomplete weld defects can be reduced, and the weld throat size and the quality of the welded joint can be improved; compared with electron beam welding, the limitation of the vacuum chamber on the size of the heat exchanger can be broken through, and the flexibility of the heat exchanger welding can be significantly improved; the cooperation of the six-axis robot and the galvanometer laser enables the laser beam to irradiate the weld at a certain laser incident angle α, avoiding the interference of the extended tube sheet with the vertically incident laser beam during the galvanometer laser welding, and due to the introduction of the weld tracking system and the molten pool monitoring system, the stability of the welding process can be effectively improved, rework can be reduced, and the welding production efficiency can be improved.

[0022] 2. The present invention adopts a galvanometer laser beam with concentrated energy, small heat input, strong penetration ability and good controllability as a welding heat source, which can accurately control the heat input, reduce welding deformation, and avoid the incomplete penetration defects that are prone to occur in the arc sealing process, effectively improving the comprehensive performance of the sealing joint; 3. The present invention adopts the CAD model to generate the laser beam scanning path. The weld tracking system and the molten pool monitoring system adjust the laser beam scanning path, welding parameters and incident angle α in real time, which can greatly improve the sealing efficiency while ensuring the stability of the sealing process.

[0023] 4. The present invention avoids oxidation during the titanium alloy welding process by means of argon-filled protection through a flexible protective device, greatly improves the adaptability of the sealing and welding equipment to the tube sheet size, reduces the waste of protective gas, avoids the heat exchange tube interfering with the protective atmosphere environment, improves the reliability and stability of the welding process, and helps to improve welding efficiency.

[0024] 5. The present invention provides a moving device to drive the weld profile collector and the molten pool profile collector to achieve circumferential movement, thereby solving the problem that the fixed weld profile collector and the molten pool profile collector cannot collect real-time information on the weld and the molten pool. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 This is a schematic diagram of the titanium alloy tube sheet galvanometer sealing welding system; Figure 2 This is a schematic diagram of the titanium alloy tube sheet weld; Figure 3 It is a top view diagram of the installation of the system's weld profile collector and molten pool profile collector; Figure 4 It is a schematic diagram of the installation of the system weld profile collector and the molten pool profile collector; Figure 5 Schematic diagram of the rotating bracket structure of the weld morphology collector.

[0026] Description of reference numerals: 1. Galvanometer laser head; 2. Galvanometer controller; 3. Weld profile collector; 4. Weld image controller; 5. Molten pool profile collector; 6. Molten pool image controller; 7. Plate; 8. Flexible protection device; 9. Industrial robot; 10. Robot controller; 11. Master controller; 12. Laser; 13. Laser beam; 14. Heat exchange tube; 15. Weld; 16. Fixed bracket; 17. Annular track; 18. Rotating bracket for weld profile collector; 19. Rotating bracket for molten pool profile collector; 20. Connecting bracket; 21. Drive unit; 22. Bracket seat; 23. Roller. DETAILED DESCRIPTION

[0027] In order to make the technical means, objectives and effects of the present invention easy to understand, the embodiments of the present invention are described in detail below with reference to specific drawings.

[0028] It should be noted that all the terms used in the present invention to indicate directionality and position, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "lower", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0029] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0031] like Figure 1-2 As shown, the present invention discloses a galvanometer laser sealing welding method for titanium alloy tube sheet, which comprises the following specific steps: S1: Assembling the titanium alloy heat exchange tube 14 and the plate 7; S2: placing the galvanometer laser head 1, the weld profile collector 3, the molten pool profile collector 5 and the welding area in the flexible protection device 8; S3: The CAD model of the tube sheet is input into the main controller 11 to generate the laser beam scanning path and the motion path of the industrial robot 9; S4: During the welding process, the weld tracking system collects information about the actual T-weld morphology and the surrounding environment of the weld, and then adjusts the laser beam scanning path and the laser incident angle α; the molten pool detection system collects the molten pool morphology during the sealing process, and then adjusts the laser process parameters; S5: After the sealing welding is completed, the tube sheet needs to be cooled before being taken out from the flexible protection device 8.

[0032] By assembling the titanium alloy tube sheet, ensure that the position between the heat exchange tube 14 and the plate 7 is accurate, and pre-tighten the heat exchange tube 14 on the plate 7 by mechanical means to prepare for subsequent welding; due to the characteristics of titanium alloy itself, a flexible protective device 8 is used to protect the welding area to prevent external air from entering, avoiding the limitation of the size of the tube sheet by the size of the vacuum chamber, and also reducing the waste of protective gas to a certain extent. At the same time, the galvanometer laser head 1, the weld morphology collector 3 and the molten pool morphology collector 5 are placed in a suitable position for welding and real-time monitoring; the CAD model of the tube sheet is input into the main controller 11 , generate the laser beam scanning path and the motion path of the industrial robot 9, conveniently control the galvanometer laser head 1 to move along with the weld 15, and effectively improve the work efficiency of the welding process; during the welding process, use the weld tracking system and the molten pool monitoring system to actually monitor the weld morphology, weld environment, and molten pool morphology, and adjust the laser beam scanning path, laser incident angle α, and laser process parameters according to the collected information to improve the welding quality; the welded tube sheet is placed in the flexible protection device 8 for a period of time to prevent the high-temperature titanium alloy tube sheet from being oxidized by contacting oxygen in the air after welding, which helps to improve the mechanical properties of the welded joint.

[0033] The titanium alloy tube sheet galvanometer laser sealing welding method can utilize the mutual cooperation of the galvanometer laser welding system, the weld tracking system and the molten pool monitoring system, greatly improving the flexibility and welding depth during the titanium alloy tube sheet sealing welding, overcoming the limitation of the tube sheet position due to tungsten inert gas arc welding, effectively reducing the defects such as the lack of fusion during the sealing welding process, and greatly improving the sealing welding efficiency and quality; it solves the problem of the interference of the heat exchange tube 14 extending out of the plate 7 with the laser beam 13 during normal laser galvanometer welding, breaks through the limitation of the vacuum chamber on the size of the parts during the titanium alloy tube sheet sealing welding, and effectively improves the stability of the sealing welding process through the application of the weld tracking system.

[0034] The laser 12 serves as a light source to generate a high-energy-density laser beam 13 for welding metal materials. The output laser power can be adjusted according to the power set in the welding program to meet different welding requirements. The galvanometer controller 2 is responsible for controlling the movement trajectory of the galvanometer reflector to ensure that the laser beam 13 is welded along a predetermined path.

[0035] Specifically, the weld tracking system and the molten pool monitoring system of the present invention mainly track and monitor the T-shaped weld 15 between the heat exchange tube 14 and the plate 7 .

[0036] Specifically, the diameter of the heat exchange tube 14 does not exceed 30 mm.

[0037] Specifically, the materials of the plate 7 and the heat exchange tube 14 are both TA24.

[0038] Specifically, in step S1, before assembly, the remaining oil stains on the tube sheet to be welded are cleaned by pickling, and then the area to be welded is wiped with acetone, and then assembly is performed, and then compressed air is used to clean dust particles on the surface of the tube sheet.

[0039] First, soak the tube sheet to be welded in the pickling solution for a certain period of time. Determine the pickling time according to the degree of contamination and the concentration of the pickling solution. After the pickling is completed, rinse off the residual acid thoroughly with clean water to ensure that no residual acid remains on the surface of the tube sheet. Finally, wipe off the moisture with a clean cloth or paper towel.

[0040] To further remove residual oil and grease on the surface, use a clean lint-free cloth or cotton swab to dip in an appropriate amount of acetone and evenly wipe the area to be welded, especially the holes on the tube sheet and the insertion part of the heat exchanger. Repeat the wiping several times until the surface is clean and oil-free.

[0041] After assembly, blow the tube sheet surface with compressed air to remove dust particles. Check again to ensure that the surface is clean and dust-free.

[0042] This setting can ensure that the titanium alloy tube sheet reaches the best cleaning state before welding, thereby improving the welding quality and sealing performance.

[0043] Preferably, the pickling solution may be a diluted hydrochloric acid or nitric acid solution.

[0044] Specifically, in step S1, the titanium alloy tube sheet is assembled, and the verticality of the tube wall and the plate is ensured during assembly. After the assembly is completed, the heat exchange tube 14 and the plate 7 are closely matched by using the tube expansion method.

[0045] After cleaning the plate 7, fix the plate 7 on the workbench and insert the heat exchange tubes 14 into the corresponding holes one by one to ensure that each heat exchange tube 14 is correctly inserted into place without being skewed or incompletely inserted. Use a tool such as a square to check the verticality of the heat exchange tube 14 and the plane of the plate 7 to ensure that the verticality meets the requirements.

[0046] Fix the heat exchange tube 14 on the plate 7 with a clamp to prevent the heat exchange tube 14 from shifting during the tube expansion process. Select a suitable tube expander according to the diameter of the heat exchange tube 14 to ensure that the taper and size of the tube expander match the heat exchange tube 14.

[0047] This arrangement ensures good sealing and mechanical connection between the plate 7 and the heat exchange tube 14 before welding by strictly assembling the titanium alloy tube sheet and achieving close fit between the heat exchange tube 14 and the plate 7. This not only improves the welding quality and sealing performance, but also provides a basis for monitoring subsequent laser welding. Through strict verticality inspection and tube expansion operations, the reliability and service life of the final product can be significantly improved.

[0048] Specifically, in step S2, the weld profile collector 3 and the molten pool profile collector 5 are installed on the galvanometer laser head 1 through a height-adjustable tooling, and the relative positions of the weld profile collector 3 and the molten pool profile collector 5 and the galvanometer laser head 1 can be adjusted within a certain range, so as to make certain adjustments for different types of plates 7. During the welding process, the weld profile collector 3 and the molten pool profile collector 5 are located 50mm to 100mm above the weld 15. For a new type of plate 7, the focal length, angle and position of the weld profile collector 3 and the molten pool profile collector 5 need to be adjusted before sealing, and after a certain calibration with the relative position of the plate 7, they are fed back to the main controller 11 to facilitate subsequent automatic tracking and adjustment.

[0049] This setting uses a height-adjustable tooling to install the weld profile collector 3 and the molten pool profile collector 5 in step S2, and adjusts the positions of the weld profile collector 3 and the molten pool profile collector 5 during the welding process, so as to achieve adaptive adjustment to different types of plates 7 and improve welding quality and efficiency. At the same time, it can not only reduce welding defects and improve welding quality, but also optimize the welding process through automatic tracking and adjustment, reduce downtime and improve production efficiency.

[0050] Specifically, in step S2, a moving device is provided on the galvanometer laser head 1, the moving device is connected to the weld profile collector 3 and the molten pool profile collector 5, and the moving device is used to drive the weld profile collector 3 and the molten pool profile collector 5 to move circumferentially.

[0051] The heat exchange tube 14 extends out of the surface of the plate 7 at a height H. When the galvanometer laser head 1 moves to the top of the heat exchange tube 14 for sealing welding, the galvanometer laser head 1 does not move, and the moving device drives the weld morphology collector 3 and the molten pool morphology collector 5 to move circumferentially, thereby avoiding the problem that the extended part of the heat exchange tube 14 blocks the circular weld 15, and the fixedly installed weld morphology collector 3 and the molten pool morphology collector 5 cannot completely collect the weld 15 and the molten pool.

[0052] Specifically, Figure 3-5 A circular track 17 is provided on the galvanometer laser head 1 shown, and the circular track 17 is fixed to the galvanometer laser head 1 through a connecting rod. The weld morphology collector 3 and the molten pool morphology collector 5 are distributed on both sides of the heat exchange tube 14 and can rotate 360° along the circular track 17. During the sealing process, the weld morphology collector 3 is in front, and the specific conditions of the extension length of the weld 15 and the heat exchange tube 14 are collected and fed back to the main controller 11. The rotation speed of the molten pool morphology collector 5 is consistent with the laser beam 13, and the condition of the molten pool is monitored, fed back to the main controller 11, and certain feedback is made.

[0053] The circular track 17 is installed on the galvanometer laser head 1 and fixed by a connecting rod. The weld morphology collector 3 and the molten pool morphology collector 5 are distributed on both sides of the heat exchange tube 14 and can rotate 360° following the circular track 17 to ensure all-round monitoring of the weld 15 and the molten pool during the sealing process. Through the design of the circular track 17, the weld morphology collector 3 and the molten pool morphology collector 5 have high flexibility and can adapt to the needs of different working conditions.

[0054] This arrangement provides a circular track 17 on the galvanometer laser head 1 and allows the weld profile collector 3 and the molten pool profile collector 5 to rotate 360 ​​degrees, thereby enabling all-round monitoring of the weld 15 and the molten pool, thereby improving welding quality and efficiency.

[0055] Specifically, the circular track 17 is fixed on the galvanometer laser head 1 through the fixed bracket 16, and the weld profile collector 3 and the molten pool profile collector 5 are connected to the circular track 17 through the weld profile collector rotating bracket 18 and the molten pool profile collector rotating bracket 19 respectively. The weld profile collector rotating bracket 18 and the molten pool profile collector rotating bracket 19 have servo motor systems inside, and are controlled by the weld image controller 4 and the molten pool image controller 6 respectively. The weld profile collector 3 and the molten pool profile collector 5 are distributed on both sides of the heat exchange tube 14 and can rotate 360° along the track. During the sealing process, the weld profile collector 3 collects the specific conditions of the extension length H of the weld 15 and the heat exchange tube 14 in front and feeds them back to the weld image controller 4. The weld image controller 4 feeds back the corresponding signal to the main controller 11 to adjust the laser incident angle α and the welding position.

[0056] This setting connects the weld morphology collector 3 and the molten pool morphology collector 5 to the galvanometer laser head 1 through a fixed bracket 16. The weld morphology collector 3 and the molten pool morphology collector 5 are connected to the circular track 17 through a weld morphology collector rotating bracket 18 and a molten pool morphology collector rotating bracket 19, respectively, which can maximize the welding quality and the reliability of the equipment. The relative positions of the weld morphology collector 3 and the molten pool morphology collector 5 can also be adjusted as needed, which can maximize the welding quality and the reliability of the equipment.

[0057] Preferably, the diameter of the annular track 17 is in the range of 100-150 mm.

[0058] Specifically, Figure 4 As shown, the weld profile collector rotating bracket 18 includes a connecting bracket 20, a driving unit 21 and a bracket seat 22. The connecting bracket 20 is arranged on the bracket seat 22 for connecting the weld profile collector 3; the driving unit 21 is arranged inside the bracket seat 22, and the bracket seat 22 is provided with a roller 23. The driving unit 21 is connected with the roller 23 for the roller 23 to move on the circular track 17.

[0059] Preferably, the bracket seat 22 is a U-shaped structure, and two side walls of the bracket seat 22 are respectively connected to the upper and lower surfaces of the annular track 17 through rollers 23.

[0060] Preferably, the connecting bracket 20 is a hinge rod, which can adjust the angle of the weld profile collector 3.

[0061] Preferably, the driving unit 21 is a servo motor system.

[0062] Preferably, the width of the bracket seat 22 is adjustable to facilitate installation and disassembly.

[0063] Specifically, the structure of the molten pool profile collector rotating bracket 19 is the same as that of the weld profile collector rotating bracket 18 .

[0064] Specifically, in step S2, the flexible protective device 8 includes a flexible film and an adhesive tape, wherein the flexible film is used to cover the welding area to construct a protective atmosphere environment, and the adhesive tape is used to seal the edge of the flexible film.

[0065] Use a flexible film to cover the welding area, and ensure that there is sufficient margin to seal the welding area, the galvanometer laser head 1, the weld morphology collector 3 and the molten pool morphology collector 5, and do not affect the movement of the galvanometer laser head 1, the weld morphology collector 3 and the molten pool morphology collector 5, and then use adhesive tape to fix the edge of the flexible film to ensure sealing performance.

[0066] The configuration uses vacuum bag film and adhesive tape to construct the flexible protection device 8, which can flexibly adjust the size according to the size of the plate 7, effectively solving the limitation of the vacuum chamber size on the tube sheet size, and also reducing the waste of protective gas to a certain extent.

[0067] Specifically, in step S2, the flexible protective device 8 is provided with an air inlet and an air exhaust hole, the air inlet is used for filling with argon, and the air exhaust hole is used for exhausting air, so as to achieve a dynamic balance of the oxygen content. After the sealing is completed, an argon flushing operation is performed to maintain the oxygen content in the flexible protective device 8 at a level not higher than 50ppm.

[0068] An air inlet and an air outlet are provided on the flexible protective device 8. During the argon filling stage, argon can be filled in and the air in the flexible protective device 8 can be discharged, thereby reducing the oxygen content to a level not higher than 50ppm and avoiding excessive oxygen content in the flexible protective device 8.

[0069] This setting can achieve a stable protective atmosphere in the flexible protective device 8, effectively prevent the titanium alloy plate 7 and the heat exchange tube 14 from being contaminated by the outside world during welding, ensure the welding quality, help improve the sealing and mechanical strength of the welded joint, and through strict sealing operations and the filling of protective gas, can significantly improve the reliability and service life after welding.

[0070] Specifically, the flexible protection device 8 is provided with at least two hole assemblies for filling argon or exhausting air. The hole assembly is made of hard high-temperature resistant plastic. The hole assembly includes an isolation plate and a through hole. The center line of the isolation plate coincides with the center line of the through hole. Filter holes are evenly distributed on the isolation plate. The outside of the air inlet is protected by a high-temperature resistant film and is equipped with a trachea quick plug. The trachea quick plug is used for connecting the argon gas pipe.

[0071] Argon gas is filled in through the hole assembly to exhaust air, reduce the oxygen content in the welding area, form an inert gas protection environment, prevent metal oxidation during welding, and improve welding quality. The filter holes on the isolation plate can improve the stability of the airflow filled with inert gas, avoid turbulence and affect the protection effect. The high-temperature resistant film protection on the outside of the air inlet can prevent external impurities from entering the equipment. The hole assembly is made of hard and high-temperature resistant plastic and can be used for a long time in a high-temperature environment without damage. It is equipped with a gas pipe quick plug, which can quickly connect the argon gas pipe for easy operation and maintenance. The center line of the isolation plate coincides with the center line of the through hole to ensure the consistency of the gas flow path and improve the gas flow efficiency.

[0072] This setting can effectively protect the welding environment and improve the welding quality by setting a hole component in the flexible protective device 8 and filling it with argon or exhausting air. It can not only reduce impurity contamination during the welding process and improve the welding quality, but also improve the reliability and work efficiency of the equipment through high temperature resistant materials and quick connection design.

[0073] Specifically, the diameter range of the through hole is 80-120 mm, the diameter range of the filter hole is 0.5-2 mm, and the diameter range of the trachea quick plug is 10-15 mm.

[0074] Preferably, the diameter of the through hole is 100 mm, the diameter of the filter hole is 1 mm, and the diameter of the trachea quick plug is 12 mm.

[0075] Argon filling holes are arranged at the bottom of the flexible protective device 8, and exhaust holes are arranged at the top to facilitate the discharge of air. The exhaust holes are made of hard high-temperature resistant plastic with a diameter of φ100mm and covered with φ1.0mm small holes. The inside of the argon punching hole is also a hard high-temperature resistant plastic plate with a diameter of φ100mm and covered with φ1.0mm small holes. The outside is protected by a high-temperature resistant film and equipped with a φ12mm air pipe quick plug to facilitate the connection of the argon pipe. The φ1.0mm small holes ensure the stability of the gas filling and discharge process. Argon is filled in from the argon filling hole at a speed of 25L / min, and air is discharged stably from the exhaust port. When the oxygen meter content in the working area is lower than 50ppm, welding operations can be carried out. At this time, the filling speed of argon can be reduced to 15L / min, reducing the consumption of protective gas. Inflation and exhaust are continuously carried out during welding to ensure that the oxygen concentration in the working area is always lower than 50ppm, effectively avoiding oxidation of the weld 15. At the same time, the flow of protective gas can take away part of the welding heat and improve the welding quality of the sealing joint.

[0076] Specifically, in step S3, the main controller 11 has a built-in existing sealing parameter process library. When the diameter, wall thickness, hole bridge width and extension length of the heat exchange tube 14 are input, the corresponding sealing speed, laser power, laser pulse width, defocus amount and other process parameters will be automatically matched.

[0077] When the pipe hole to be sealed is within the φ100mm range of the plane directly below the galvanometer laser head 1, the galvanometer laser head 1 adjusts the position and angle of the laser beam 13 by swinging the internal lens to quickly complete the sealing; when the pipe hole to be sealed is beyond the φ100mm range directly below the galvanometer laser head 1, the industrial robot 9 moves as the sealing progresses, ensuring the accessibility of the galvanometer laser position and angle.

[0078] The main controller 11 generates instructions according to the welding program or the real-time collected information, and sends them to the galvanometer controller 2 and the robot controller 10. After receiving the instructions, the galvanometer controller 2 and the robot controller 10 analyze the instruction content and extract the path, speed, incident angle α and other information of the laser beam 13.

[0079] The robot controller 10 controls the various joints of the industrial robot 9 according to the instructions issued by the main controller 11, so that the galvanometer laser head 1 reaches the specified position. The robot controller 10 is responsible for adjusting the posture of the industrial robot 9 to ensure that the laser beam 13 can be welded in the correct posture. The galvanometer controller 2 and the robot controller 10 need to coordinate to ensure that the movement of the laser beam 13 is synchronized with the movement of the industrial robot 9. During the welding process, if an unexpected situation occurs, such as the weld 15 deviates from the expected path, the main controller 11 will issue new instructions, and the galvanometer controller 2 and the robot controller 10 will make real-time adjustments based on the new instructions.

[0080] The galvanometer controller 2 is responsible for decomposing the path information sent by the main controller 11 into control instructions for the galvanometer reflector. The galvanometer controller 2 plans the movement speed and acceleration curve of the galvanometer reflector according to the speed information in the instructions. The galvanometer controller 2 adjusts the angle of the galvanometer reflector according to the laser incident angle α in the instructions to ensure that the laser beam 13 is incident on the welding area at the correct angle. If the incident angle needs to be dynamically adjusted during the welding process, the galvanometer controller 2 will make corresponding adjustments according to the real-time instructions of the main controller 11.

[0081] Specifically, in step S3, the laser incident angle is α, 0°<α< ; Where: B is the width of the hole bridge; H is the extended length of the heat exchange tube 14.

[0082] The laser incident angle α is a reasonable solution given by the master controller 11 based on the existing process database, comprehensive welding efficiency and quality. When the laser incident angle α is small and close to vertical incidence, the movement path of the galvanometer laser head 1 is the shortest, and the sealing efficiency is high, but the wall of the heat exchange tube 14 will interfere with the laser beam 13 reaching the weld 15. When the laser incident angle α is large, the adjacent heat exchange tube 14 will interfere with the path of the laser beam 13 reaching the weld 15, and at this time the galvanometer laser head 1 needs to move more paths to complete the sealing of a single tube hole, and the efficiency is relatively low. The galvanometer controller 2 and the robot controller 10 are controlled by the master controller 11 to control the industrial robot 9 and the galvanometer laser head 1 so that the laser beam 13 performs scanning welding according to the given path and laser incident angle α.

[0083] The laser incident angle α can prevent the laser beam 13 from being disturbed by the wall of the heat exchange tube 14, maintain a high absorption rate of the titanium alloy to the laser, better control spatter and other problems during the welding process, obtain a larger welding width and welding depth, a more regular weld 15, and avoid problems such as cracks.

[0084] Preferably, the extended length H of the heat exchange tube 14 is in the range of 0 mm to 5 mm.

[0085] Preferably, the laser incident angle α is 5°~10°.

[0086] This setting of the laser incident angle can optimize factors such as the spatter plasma cloud and weld shape during the welding process, further improving the welding quality.

[0087] Specifically, in step S3, during the sealing process, the galvanometer laser head 1 is located on the central axis of the heat exchange tube 14. The galvanometer laser head 1 is a variable focal length device, and the focal length can be changed in the range of 275-325mm. The laser power is 0~6000W, the defocus is ~3~+3, and the welding speed is 0~15m / min.

[0088] The galvanometer laser head 1 is located on the central axis of the heat exchange tube 14, so that the circumferential weld 15 is located directly below the galvanometer laser head 1, which facilitates the laser beam 13 to scan the circumferential weld 15 and reduce the interference of the heat exchange tube 14 on the laser. At the same time, the galvanometer laser head 1 sets a unified positioning standard, which helps to reduce positioning errors and reduce the calculation amount of laser scanning.

[0089] This setting uses a galvanometer laser head 1 during the sealing process and accurately controls the focal length, power, defocus and welding speed, which can not only improve the welding quality and reduce welding defects, but also adapt to the welding requirements of various materials and thicknesses, thereby improving production efficiency and equipment reliability.

[0090] Preferably, the distance between the lower side of the galvanometer laser head 1 and the plane of the plate 7 is 300 mm±5 mm.

[0091] Preferably, the welding parameters are as shown in Table 1. Table 1

[0092] Specifically, in step S3, the plurality of welds 15 on the plate 7 are welded in a staggered welding manner.

[0093] Staggered welding can make the heat more evenly distributed during the welding process, gradually release stress, avoid deformation caused by concentrated stress, and at the same time make the weld 15 more evenly filled, reduce defects such as cracks and pores during the welding process, reduce the problems of incomplete fusion and incomplete penetration, and improve welding quality.

[0094] This arrangement can effectively reduce welding deformation, improve welding quality, and improve welding efficiency by welding multiple welds 15 on the tube sheet in a staggered welding manner, which can not only reduce welding defects, but also improve the welding environment and reduce welding costs. By reasonably arranging the welding sequence and parameters, the welding quality and production efficiency can be maximized, thereby improving the reliability and service life of the equipment.

[0095] Specifically, in step S4, the weld morphology collector 3 in the weld tracking system collects the actual values ​​of the actual T-shaped weld morphology, the diameter Φ of the heat exchange tube 14, the hole bridge gap B, and the actual value of the extension length H of the heat exchange tube 14, and feeds them back to the main controller 11 through the weld image controller 4. The main controller 11 compares the theoretical value transmitted by the CAD with the actual collected value, and adjusts the laser beam scanning path and the laser incident angle α according to the actual collected value.

[0096] The weld tracking system can collect the weld 15 morphology and the surrounding environment of the weld 15 in real time, and feed back the actual situation to the main controller 11. The main controller 11 adjusts the laser beam scanning path and the laser incident angle α according to the actual collected values ​​to ensure the consistency of the laser welding angle.

[0097] This setting can adjust the laser beam scanning path and the laser incident angle according to the actual welding seam 15 processing conditions, avoid the interference of the tube sheet with the laser, effectively reduce the formation of sealing defects caused by processing errors, improve the stability of the sealing process, and ensure welding quality and efficiency.

[0098] Specifically, in step S4, the molten pool morphology collector 5 in the molten pool detection system collects the molten pool morphology of the sealing process, focusing on monitoring the spatter, keyholes, unstable vortexes and the like in the molten pool, and produces a digital signal through the molten pool image controller 6 and transmits it to the main controller 11 in real time. The main controller 11 makes timely adjustments to the laser process parameters based on the comparison with the existing laser welding molten pool morphology database.

[0099] The molten pool morphology collector 5 collects information on the molten pool morphology such as the size, shape, spatter, keyhole, unstable vortex, etc. of the molten pool, and feeds back the relevant information to the main controller 11. The main controller 11 makes timely adjustments to the laser process parameters based on this to achieve real-time control of the welding quality.

[0100] This setting can detect abnormal conditions in the welding process in time and adjust the laser process parameters through the main controller 11 to ensure the welding quality and stability. It not only improves the automation level of welding, but also improves the welding efficiency and reliability. Through continuous optimization and improvement, the application level of laser welding technology can be further improved.

[0101] Preferably, the laser process parameters are adjusted: spatter in the welding process is suppressed by adjusting the matching of laser power and welding speed, and the keyhole formed in the welding process is stabilized by adjusting the matching of laser pulse width ratio and defocusing amount.

[0102] Laser power directly affects the temperature and size of the molten pool. Higher laser power can cause metal materials to melt and evaporate quickly, generating a large amount of vapor pressure, which can cause spatter. The welding speed determines the time the laser stays on the workpiece per unit time. Faster welding speeds allow the molten pool to cool faster, reducing the chance of spatter; slower welding speeds may cause the molten pool to overheat, increasing the risk of spatter. Reasonable adjustment of laser power and welding speed can reduce vapor pressure and avoid spatter and incomplete welding.

[0103] Laser pulse width ratio refers to the relationship between the duration of the laser pulse and the peak power. A longer pulse width can keep the molten pool at a higher temperature, which helps to form a stable keyhole. Properly increasing the laser pulse width ratio can increase the temperature of the molten pool and help to stabilize the formation of the keyhole. However, too long a pulse width may cause the molten pool to overheat, causing spatter or holes. Defocus refers to the distance between the laser focus and the workpiece surface. When the focus is above the workpiece surface, positive defocus can increase the width of the molten pool, and when the focus is below the workpiece surface, negative defocus can increase the depth of penetration. The shape and stability of the molten pool can be controlled by adjusting the defocus. Appropriate positive defocus can make the molten pool more stable and reduce the fluctuation of the keyhole.

[0104] By adjusting the laser process parameters in a timely manner, spatter during welding can be effectively suppressed and the keyhole formation can be stabilized, thereby improving welding quality and efficiency. Specifically, spatter can be suppressed by adjusting the matching of laser power and welding speed, and the keyhole can be stabilized by adjusting the matching of laser pulse width ratio and defocusing amount. These adjustments need to be continuously optimized based on experimental data and actual application conditions to achieve the best welding effect.

[0105] Specifically, the overall tracking accuracy of the weld tracking system is related to the laser scanning speed. When the laser scanning speed is in the range of 0~5m / min, the weld tracking system can ensure that a focus offset of 1mm is corrected within 5ms; when the laser scanning speed is in the range of 5~10m / min, the weld tracking system can ensure that a focus offset of 0.5mm is corrected within 5ms; when the laser scanning speed is in the range of 10~20m / min, the weld tracking system can ensure that a focus offset of 0.2mm is corrected within 5ms; for larger laser scanning speeds, due to welding quality limitations, titanium alloy tube sheet sealing is not involved, and it is also beyond the correction range of the weld tracking system.

[0106] This setting can ensure the accuracy and quality of the welding process through the real-time correction function of the weld tracking system at different laser scanning speeds. This design can not only reduce welding defects and improve welding quality, but also optimize the welding process, reduce downtime and improve production efficiency through real-time monitoring and rapid correction.

[0107] Specifically, the molten pool profile collector 5 makes the rotation speed consistent with the laser beam 13 under the joint control of the master controller 11 and the molten pool image controller 6, and monitors the molten pool in real time. The spatter, keyhole, unstable vortex, etc. in the molten pool are monitored in particular, and the digital signal produced by the molten pool image controller 6 is transmitted to the master controller 11 in real time. The master controller 11 makes timely adjustments to the laser process parameters based on the comparison with the existing laser welding molten pool profile database, such as suppressing spatter in the welding process by adjusting the matching of laser power and welding speed, and stabilizing the keyhole formed in the welding process by adjusting the matching of laser pulse width ratio and defocusing amount.

[0108] The adjustment process is based on the spatter and keyhole control technology that occurs in the existing butt weld or fillet weld laser welding process. Aiming at the characteristics of small tube holes, thin tube walls, small hole bridge spacing and the laser beam 13 must be injected at a certain angle α in the titanium alloy tube sheet sealing process, combined with machine learning methods, certain improvements and optimizations are made to make the adjustment process more in line with the characteristics of titanium alloy tube sheet sealing.

[0109] This setting monitors the molten pool in real time through the molten pool profile collector 5, and generates a digital signal through the molten pool image controller 6 and transmits it to the main controller 11. The main controller 11 makes timely adjustments to the laser process parameters based on the comparison of the molten pool profile database. This design can not only reduce welding defects and improve welding quality, but also optimize the welding process, reduce downtime, and improve production efficiency through real-time monitoring and rapid adjustment.

[0110] Specifically, after the sealing welding is completed, the tube sheet needs to be cooled to a temperature not higher than 100° C. before being taken out from the flexible protection device 8 .

[0111] By natural cooling or forced cooling, the temperature of the titanium alloy tube sheet after welding is ensured to be no higher than 100°C before being taken out from the flexible protection device 8, which can effectively prevent the titanium alloy from being oxidized due to excessive temperature and ensure the quality and safety of welding. During the cooling process, it is necessary to pay close attention to the temperature changes and take appropriate measures to ensure the uniformity and safety of cooling.

[0112] Example 1

[0113] The novel titanium alloy tube sheet galvanometer laser sealing welding method provided by the present invention has a typical novel heat exchanger structure in which the plate 7 and the heat exchange tube 14 are both made of TA24, the specification of the heat exchange tube 14 is Φ12×1, the spacing between the heat exchange tubes 14 is 3mm, and the length of the heat exchange tube 14 extending from the plate 7 is 2mm. The specific process steps are as follows: clean the heat exchange tube 14 and the plate 7, remove the oil stains with acetone, alcohol solvent and ultrasonic cleaning, place them in the flexible protection device 8, and then flush with argon to make the oxygen content ≤50ppm; import the tube sheet CAD model into the main controller 11 to generate the laser beam scanning path, give the starting point of the laser beam 13 scanning, the power curve and defocus of the laser, and adjust in real time through the weld tracking system and the molten pool monitoring system to complete the sealing welding of the entire tube sheet, and take it out of the flexible protection device 8 after the tube sheet is cooled to no more than 100°C, and the sealing welding work is completed.

[0114] After welding is completed, the joint structure is analyzed using a metallographic microscope, and no pores, cracks, or incomplete penetration defects are found; penetration testing is performed, and it meets NB / T 47013.5 Level Ⅰ qualification.

[0115] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A galvanometer laser sealing welding method for titanium alloy tube sheet, It is characterized in that The specific steps include: S1: Assembling the titanium alloy heat exchange tube (14) and the plate (7); S2: placing the galvanometer laser head (1), the weld profile collector (3), the molten pool profile collector (5), and the welding area in a flexible protective device (8); S3: The CAD model of the titanium alloy tube sheet is input into the main controller (11) to generate the laser beam scanning path and the motion path of the industrial robot (9); S4: During the welding process, the weld tracking system collects information about the actual T-weld morphology and the surrounding environment of the weld, and then adjusts the laser beam scanning path and the laser incident angle α; the molten pool detection system collects the molten pool morphology during the sealing process, and then adjusts the laser process parameters; S5: After the sealing welding is completed, the tube sheet needs to be cooled before being removed from the flexible protection device (8).

2. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S1, the titanium alloy tube sheet is assembled, and the verticality of the heat exchange tube (14) and the plate (7) is ensured during assembly. After the assembly is completed, a tube expansion method is used to achieve a close fit between the heat exchange tube (14) and the plate (7).

3. According to the galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S2, a moving device is provided on the galvanometer laser head (1), the moving device is connected to the weld seam morphology collector (3) and the molten pool morphology collector (5), and the moving device is used to drive the weld seam morphology collector (3) and the molten pool morphology collector (5) to move circumferentially.

4. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 3, It is characterized in that The moving device comprises a fixed support (16), a circular track (17), a weld profile collector rotating support (18) and a molten pool profile collector rotating support (19); the circular track (17) is fixed to the galvanometer laser head (1) via the fixed support (16); the weld profile collector (3) is connected to the circular track (17) via the weld profile collector rotating support (18); the molten pool profile collector (5) is connected to the circular track (17) via the molten pool profile collector rotating support (19); the weld profile collector rotating support (18) and the molten pool profile collector rotating support (19) are capable of circumferential movement on the circular track (17).

5. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S2, the flexible protective device (8) comprises a flexible film and an adhesive tape, wherein the flexible film is used to cover the welding area to create a protective atmosphere environment, and the adhesive tape is used to seal the edge of the flexible film. The flexible protective device (8) is provided with an air inlet and an air outlet, wherein the air inlet is used to fill argon gas, and the air outlet is used to discharge air. After the sealing is completed, an argon filling operation is performed to ensure that the oxygen content in the flexible protective device (8) is not higher than 50 ppm.

6. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S3, the laser incident angle is α, 0°<α< ; Where: B is the width of the hole bridge; H is the extended length of the heat exchange tube.

7. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S3, during sealing welding, the galvanometer laser head (1) is located on the central axis of the heat exchange tube (14). The galvanometer laser head (1) is a variable focal length device with a focal length range of 275 to 325 mm. The laser power is 0 to 6000 W, the defocus is ~3 to +3, and the welding speed is 0 to 15 m / min.

8. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S4, the weld morphology collector (3) in the weld tracking system collects the actual values ​​of the actual T-shaped weld morphology, the heat exchange tube diameter Φ, the hole bridge gap B and the heat exchange tube extension length H, and feeds them back to the main controller (11) through the weld image controller (4). The main controller (11) compares the theoretical value transmitted by the CAD with the actual collected value, and adjusts the laser beam scanning path and the laser incident angle α according to the actual collected value.

9. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S4, the molten pool morphology collector (5) in the molten pool monitoring system collects the molten pool morphology during the sealing process, focusing on monitoring the spatter, keyholes, and unstable vortices in the molten pool, and generates a digital signal through the molten pool image controller (6) and transmits it to the main controller (11) in real time. The main controller (11) adjusts the laser process parameters based on the comparison with the existing laser welding molten pool morphology database.

10. The galvanometer laser sealing welding method for titanium alloy tube sheet according to claim 1, It is characterized in that In step S5, after the sealing welding is completed, the tube sheet needs to be cooled to no higher than 100°C before being taken out from the flexible protection device (8).

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