Laser low-stress welding tool and method for stainless steel thin-walled workpiece

Abstract

The invention belongs to the technical field of laser welding, and particularly discloses a laser low-stress welding tool and method for a stainless steel thin-wall part. Comprising an inner supporting tool used for positioning, checking and clamping a cylinder; the inner supporting tool fixing module comprises a main driving position changing machine and a driven end rotation support arranged corresponding to the main driving position changing machine, and the main driving position changing machine and the driven end rotation support are each provided with a three-jaw chuck used for clamping the inner supporting tool; the corrugated plate assembly part is used for being fixedly connected with the inner supporting tool after restraining and fixing the corrugated plate; the path planning module is used for planning a welding path according to the laser welding process parameters; and the laser welding module is used for welding the stainless steel thin-wall part by adopting quasi-continuous laser according to the laser welding process parameters and the welding path. According to the invention, a welding workpiece is effectively positioned and clamped, meanwhile, the welding path is optimized, the welding thermal deformation is reduced, and the welding quality is good.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser welding, and more specifically, relates to a laser low-stress welding tool and method for stainless steel thin-walled parts. Background Art

[0002] The cylinder body welded by rolling stainless steel sheets into a cylinder has the characteristics of large circumferential diameter tolerance and poor roundness. The corrugated arc pendant punched from stainless steel sheets is difficult to maintain an ideal shape due to the high elasticity of stainless steel materials. Therefore, the combination of the cylinder body and the corrugated plate pendant is difficult to weld. Figure 1 As shown. The welded parts are as follows Figure 2 As shown, the actual corrugated plate is welded to the cylinder. One of the difficulties is that the corrugated arc hanger and the cylinder must be shaped to keep the ideal shape or approximate the ideal shape, and the corrugated arc hanger is constrained and shaped by the contouring tooling of the corrugated arc hanger, such as Figure 3 As shown, the inner support fixture of the cylinder is used to shape its roundness. The second difficulty is that the position of the weld is at the position where each corrugated arc hanger contacts the cylinder, and the overlap welding is performed, such as Figure 4 As shown in the figure, the distance between the troughs (wave channels) is small, so the density of the weld is large, which may lead to large local heat input. The thin-walled stainless steel material is subjected to uneven heating and cooling inside, thus generating welding residual stress. In places with high temperatures, the welding expansion is large and the stress increases. In places with low temperatures, the expansion of the weld is small and the stress is small, resulting in reduced welding quality and obvious welding deformation. The workload of later correction is large, and its performance is seriously affected.

[0003] Compared with traditional welding, pulse laser welding can achieve higher power density in a single pulse at a lower average output power, and can control heat input more flexibly. It has the advantages of concentrated energy, low heat input, narrow weld and small deformation. Moreover, a very small spot can be obtained after the laser beam is focused, and it can be precisely positioned. There is no mechanical force between the laser beam and the workpiece, and no mechanical force is applied to the component during the welding process. These characteristics make laser welding more suitable for welding ultra-thin-walled workpieces than other welding methods. Under the conditions of pulse laser welding, with the flexible welding tooling, thin-walled stainless steel parts are shaped, positioned and clamped to ensure that the welding conditions can meet the conditions of high-quality and high-efficiency welding. On this basis, the optimal welding implementation path and welding process parameters are determined in combination with numerical simulation and simulation technology and experimental methods. Through this combined method, laser welding of thin-walled low-stress stainless steel parts is achieved. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the present invention provides a laser low-stress welding tool and method for stainless steel thin-walled parts. Under the condition of pulsed laser welding, it cooperates with flexible welding tooling to shape, position and clamp thin-walled stainless steel parts to ensure that the welding conditions can meet the conditions of high-quality and high-efficiency welding. On this basis, it cooperates with numerical simulation and simulation technology and experimental methods to determine the best welding implementation path and welding process parameters. Through this combined method, laser welding of stainless steel thin-walled low-stress parts can be achieved. On the one hand, the quality of the welding weld can be guaranteed, and on the other hand, automated processing methods can be used to improve production efficiency. In addition, by using high-quality welding heat sources, the heat input during workpiece welding can be reduced, welding thermal deformation can be reduced, and the purpose of green energy saving can be achieved; by combining numerical simulation with experiments, the welding quality of the entire workpiece can be effectively improved.

[0005] To achieve the above object, according to one aspect of the present invention, a laser low-stress welding tool for stainless steel thin-walled parts is provided, comprising:

[0006] Internal support fixture, used to position, inspect and clamp the cylinder;

[0007] An inner support fixture fixing module, which includes a main drive positioner and a driven end rotary support corresponding to the main drive positioner, and the main drive positioner and the driven end rotary support are both provided with a three-jaw chuck for clamping the inner support fixture;

[0008] The corrugated plate assembly is used to constrain and fix the corrugated plate and then fix it with the inner support tooling;

[0009] A path planning module is used to plan the welding path according to the laser welding process parameters;

[0010] The laser welding module is used to weld stainless steel thin-walled parts using quasi-continuous laser according to laser welding process parameters and welding paths.

[0011] As a further preferred embodiment, the inner support tooling comprises an inner support main shaft, an inner support support seat, a plurality of radius-adjustable support members circumferentially arranged along the cross-section of the inner support main shaft and movably connected to the inner support support seat, and an inner support driving member driving the radius-adjustable support member to move radially along the inner support main shaft, in this way, the circular cross-section formed by the plurality of radius-adjustable support members is adjusted according to the radius design requirements of the cylinder;

[0012] The inner support tooling also includes external pressure support rings arranged at both axial ends of the inner support main shaft, wherein the external pressure support rings are fixedly connected to the inner support main shaft.

[0013] As a further preference, the inner support fixture fixing module comprises a workbench, on which is provided a slide rail for the rotational support movement of the driven end, and the slide rail is arranged along the axis of the inner support main shaft.

[0014] As a further preference, the corrugated plate assembly includes an assembly body and a plurality of restraining parts fixed on the assembly body, the restraining parts are used to restrain a crest of the corrugated plate so that the shape of the crest meets the design requirements, and adjacent restraining parts are arranged at intervals to reserve welds for welding the corrugated plate.

[0015] As a further preferred embodiment, the corrugated plate assembly also includes a plurality of external clamping fixtures for fixing the assembly body on the inner supporting fixture, the external clamping fixture including a mounting surface fixing piece arranged to be attached to the circumferential outer wall of the inner supporting fixture and an external clamping fixture corresponding to the mounting surface fixing piece for fixing the assembly body on the mounting surface fixing piece.

[0016] As a further preferred embodiment, the path planning module includes: performing multi-physical field coupling simulation of the welding process according to the laser welding process parameters to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process; constructing a weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate, and accordingly planning the welding paths of multiple spaced-apart straight welds on multiple corrugated plates.

[0017] As further preferred, the laser welding module includes a quasi-continuous laser for welding.

[0018] According to another aspect of the present invention, there is also provided a laser low stress welding method for stainless steel thin-walled parts, comprising the following steps:

[0019] Step 1: Use the inner support fixture to position, check and clamp the cylinder, and then drive the main drive positioner and the driven end rotary support to clamp the inner support fixture;

[0020] Step 2: After the corrugated plate is constrained and fixed by the corrugated plate assembly, the position relationship of the corrugated plate relative to the cylinder is converted into the position relationship of the corrugated plate assembly relative to the cylinder, so as to position the corrugated plate, and adjust the rotation angle of the inner support tooling according to the positioning, and fix the corrugated plate assembly to the inner support tooling to complete the positioning and fixing of the corrugated plate in sequence;

[0021] Step three: according to the laser welding process parameters and welding path, the stainless steel thin-walled parts are welded using quasi-continuous laser.

[0022] As further preferred, the step 2 comprises the following steps:

[0023] (201) Designing the shape of the restraining member and the spacing distance between adjacent restraining members according to the shape of the corrugated plate, so that under the restraining action of the restraining member, the wave crest shape of the corrugated plate meets the design requirements, and at the same time, the spacing distance between adjacent restraining members at least covers the weld to be processed;

[0024] (202) The positional relationship of the corrugated plate relative to the cylinder is converted into the positional relationship of the corrugated plate assembly relative to the cylinder, and according to the positional relationship, the first corrugated plate assembly constrained by the corrugated plate is installed on the inner support fixture, and then the inner support fixture is rotated to a specified angle to install the next corrugated plate assembly constrained by the corrugated plate, until all the corrugated plate assemblies constrained by the corrugated plates are installed.

[0025] As further preferred, the step three comprises the following steps:

[0026] (301) According to the laser welding process parameters, multi-physics field coupling simulation is performed on the welding process to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process;

[0027] (302) A weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint is constructed to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate, and to plan the welding paths of multiple linear welds arranged at intervals on multiple corrugated plates;

[0028] (303) sequentially laser processing the first weld of each corrugated plate until the first weld of all the corrugated plates is processed;

[0029] (304) processing the second weld of each corrugated plate in sequence according to the optimal weld spacing between two adjacent welding steps of each corrugated plate until the second weld of all the corrugated plates is processed;

[0030] (305) Repeat step (304) until all welds on all corrugated plates are processed.

[0031] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0032] 1. The present invention adopts a flexible welding tool to clamp the workpiece. The main body of the flexible tool can effectively position and clamp the workpiece. The tool can serve as both a mold and a gauge, and also has the function of a clamp. At the same time, it can also take into account workpieces of different specifications and sizes. It has multifunctional and multi-dimensional flexibility. This tool can ensure that the incoming material quality, assembly quality of thin-walled corrugated plates and thin-walled cylinders, and the gap between the assembled parts to be welded meet the welding requirements, thereby laying the foundation for ensuring the final welding quality.

[0033] 2. The present invention adopts a laser welding heat source with low heat input and low heat affected zone. The laser light source has controllable and adjustable parameters such as laser power, pulse frequency, pulse width, duty cycle, and waveform control. Under the premise of ensuring the quality of the welding weld, the heat input of the welding heat source can be reduced.

[0034] 3. The present invention adopts numerical simulation and emulation technology to rationally plan the welding path to avoid local concentration of welding heat, which may cause local thermal deformation and thus affect the accuracy of the entire workpiece.

[0035] 4. The present invention adopts an orthogonal test method to determine the optimal welding process parameters. The quality of laser welding is the result of the combined effect of multiple factors. The optimal process parameters are obtained through scientific experiments, thereby realizing laser low-stress welding of stainless steel thin-walled parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 (a) is the theoretical corrugated plate shape. Figure 1 (b) is the actual corrugated plate shape. Figure 1 (c) in the figure is a theoretical cylindrical shape. Figure 1 (d) in the figure is the actual cylindrical shape;

[0037] Figure 2 It is a schematic diagram of the welding of stainless steel thin-walled workpieces involved in the present invention;

[0038] Figure 3 Schematic diagram of a corrugated arc-shaped pendant profiling tooling according to an embodiment of the present invention;

[0039] Figure 4 is a schematic diagram of the weld position involved in an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of the structure of a laser low-stress welding tool for stainless steel thin-walled parts according to an embodiment of the present invention.

[0041] Figure 6 It is a result schematic diagram of the inner support tooling involved in the embodiment of the present invention;

[0042] Figure 7 It is a structural schematic diagram of a corrugated plate assembly involved in an embodiment of the present invention;

[0043] Figure 8 It is a schematic diagram of the installation and positioning of the corrugated plate involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Example 1

[0046] like Figures 1 to 7 As shown, a laser low-stress welding tool for stainless steel thin-walled parts provided by an embodiment of the present invention includes: an inner support tool 1, which is used to position, check and clamp the cylinder 4; an inner support tool fixing module 2, which includes a main drive positioner 21 and a driven end rotary support 22 corresponding to the main drive positioner 21, and the main drive positioner 21 and the driven end rotary support 22 are both provided with a three-jaw chuck 23 for clamping the inner support tool 1; a corrugated plate assembly part 3, which is used to constrain and fix the corrugated plate 5 and then fixedly connected to the inner support tool 1; a path planning module, which is used to plan the welding path according to the laser welding process parameters; a laser welding module, which is used to weld the stainless steel thin-walled parts with a quasi-continuous laser according to the laser welding process parameters and the welding path.

[0047] Optionally, in this embodiment, the inner support fixture 1 includes an inner support main shaft 11, an inner support seat 12, a plurality of radius-adjustable supports 13 movably connected to the inner support seat 12 and arranged circumferentially along the cross-section of the inner support main shaft 11, and an inner support driving member driving the radius-adjustable supports 13 to move radially along the inner support main shaft 11, so that the circular cross-section formed by the plurality of radius-adjustable supports 13 is adjusted according to the radius design requirements of the cylinder 4; the inner support fixture 1 also includes an external pressure support ring 14 provided at both axial ends of the inner support main shaft 11, wherein the external pressure support ring 14 is fixedly connected to the inner support main shaft 11. Optionally, the inner support driving member is a conventional motor drive or a driving mechanism capable of driving the radius-adjustable supports 13 to move radially along the inner support main shaft 11, both of which are suitable for the present invention.

[0048] Optionally, in this embodiment, the inner support seat 12 is a circular structure, and a slide groove is provided on the circular structure for the radius adjustable support member 13 to move. Accordingly, in a preferred embodiment of the present invention, the number of radius adjustable support members 13 corresponds to the number of corrugated plates, and their distribution along the axial direction of the inner support main shaft 11 corresponds to the distribution of the corrugated plates along the axial direction of the barrel. More specifically, in this embodiment, the radius adjustable support member 13 is an L-shaped structure, and the area of ​​the plates arranged along the circumference of the inner support main shaft 11 at least covers the area of ​​the corrugated plates arranged corresponding to it.

[0049] Optionally, in this embodiment, the inner support fixture fixing module 2 includes a workbench 24 , and the workbench 24 is provided with a slide rail for the driven end rotary support 22 to move, and the slide rail is arranged along the axis of the inner support main shaft 11 .

[0050] Optionally, in this embodiment, the corrugated plate assembly 3 includes an assembly body 31 and a plurality of restraining members 32 fixed on the assembly body 31, the restraining member 32 is used to restrain a crest of the corrugated plate so that the shape of the crest meets the design requirements, and adjacent restraining members 32 are arranged at intervals to reserve welds 6 for welding the corrugated plate 5.

[0051] Optionally, in this embodiment, the restraining member 32 is a V-shaped structure, and the V-shaped structure restrains both sides of the wave crest so that the shape of the wave crest meets the design requirements.

[0052] Optionally, in this embodiment, the corrugated plate assembly 3 also includes a plurality of external clamping fixtures 33 for fixing the assembly body 31 on the inner support fixture 1, and the external clamping fixture 33 includes a mounting surface fixing member that is attached to the circumferential outer wall of the inner support fixture 1 and an external clamping fixture that is corresponding to the mounting surface fixing member and is used to fix the assembly body 31 on the mounting surface fixing member.

[0053] Optionally, in this embodiment, the path planning module includes: performing multi-physical field coupling simulation of the welding process according to the laser welding process parameters to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process; constructing a weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate 5, and accordingly planning the welding paths of multiple spaced straight welds on multiple corrugated plates 5.

[0054] Optionally, in this embodiment, the laser welding module includes a quasi-continuous laser for welding.

[0055] Example 2

[0056] This embodiment provides a laser low-stress welding method for stainless steel thin-walled parts, comprising the following steps:

[0057] Step 1: Use the inner support fixture 1 to position, check and clamp the cylinder 4, and then drive the main drive positioner 21 and the driven end rotary support 22 to move to clamp the inner support fixture 1.

[0058] Specifically, step one includes the following steps:

[0059] Check the incoming cylinder and corrugated sheet materials separately to confirm that the quality meets the requirements;

[0060] The fixture is in place, and the cylinder is placed on the inner support fixture (in this embodiment, the inner support fixture is composed of four pieces), and one end surface is used as the reference for positioning (generally, the end where the main drive positioner is located is used as the reference for positioning), and the other end is clamped, and the center of the cylinder is used as the reference for positioning, and the inner support fixture is clamped, so as to achieve the purpose of positioning and clamping the cylinder. More specifically, as Figure 5 As shown, the left end face of the cylinder is used as the reference for positioning, and the center of the cylinder is used as the reference, and the inner support plate and the outer support are clamped; the right side external pressure support ring clamps the cylinder from the right side.

[0061] Step 2: After the corrugated plate is constrained and fixed by the corrugated plate assembly, the position relationship of the corrugated plate relative to the cylinder is converted into the position relationship of the corrugated plate assembly relative to the cylinder, so as to position the corrugated plate, and adjust the rotation angle of the inner support tooling according to the positioning, and fix the corrugated plate assembly to the inner support tooling to complete the positioning and fixing of the corrugated plate in sequence;

[0062] Specifically, this step 2 includes the following steps:

[0063] (201) The shape of the restraining member 32 and the spacing distance between adjacent restraining members 32 are designed according to the shape of the corrugated plate, so that under the restraining action of the restraining member 32, the wave crest shape of the corrugated plate meets the design requirements, and at the same time, the spacing distance between adjacent restraining members 32 at least covers the weld to be processed;

[0064] (202) Figure 8 As shown, the positional relationship of the corrugated plate 5 relative to the cylinder 4 is converted into the positional relationship of the corrugated plate assembly 3 relative to the cylinder 4, and according to the positional relationship, the first corrugated plate assembly 3 constrained with the corrugated plate 5 is installed on the inner support fixture 1, and then the inner support fixture 1 is rotated to a specified angle to install the next corrugated plate assembly 3 constrained with the corrugated plate 5, until all the corrugated plate assembly 3 constrained with the corrugated plate 5 are installed. Specifically, in one embodiment, as Figure 8 In (a), the first corrugated plate is installed first, the cylinder 4 is rotated 90 degrees, and then the second corrugated plate is installed. Figure 8 As shown in (b), the cylinder 4 is rotated 90 degrees, and then the third corrugated plate is installed, as shown in FIG. Figure 8 As shown in (c), the cylinder 4 is rotated 90 degrees, and then the fourth corrugated plate is installed, as shown in FIG. Figure 8 As shown in (d) in .

[0065] Step 3: According to the laser welding process parameters and welding path, the stainless steel thin-walled parts are welded using quasi-continuous laser. The details are as follows:

[0066] (301) According to the laser welding process parameters, multi-physics field coupling simulation is performed on the welding process to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process;

[0067] (302) A weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint is constructed to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate, and to plan the welding paths of multiple linear welds arranged at intervals on multiple corrugated plates;

[0068] (303) laser processing the first weld seam of each corrugated plate in turn until the first weld seam processing of all the corrugated plates (5) is completed;

[0069] (304) processing the second weld of each corrugated plate in sequence according to the optimal weld spacing between two adjacent welding steps of each corrugated plate until the second weld of all the corrugated plates is processed;

[0070] (305) Repeat step (304) until all welds on all corrugated plates are processed.

[0071] Optionally, in the above steps, the dynamic behavior of the molten pool is affected by various factors such as heat input, welding speed, material properties, etc. The weld spacing S needs to be large enough to avoid overlap of the heat affected zones of adjacent welds, thereby affecting the stability of the molten pool and the welding quality. The relationship between the width of the heat affected zone (HAZ) and the weld spacing is constructed based on the above factors.

[0072] In addition, the mechanical properties of the welded joint are affected by the solidification behavior and microstructure of the molten pool. The weld spacing S needs to be considered to ensure the uniformity and mechanical properties of the welded joint. In this step, a calculation model of the relationship between the temperature gradient G and the solidification rate R can be constructed. The temperature gradient G and the solidification rate R are the key parameters affecting the microstructure of the welded joint, and thus affecting the mechanical properties.

[0073] In laser welding, the multi-physics field coupling simulation model can comprehensively consider the influence of multiple physical fields such as heat, force, and fluid.

[0074] Therefore, the heat and mass transport model of the molten pool is constructed:

[0075]

[0076] Among them, ρ is density, u is velocity, h is specific enthalpy, k is thermal conductivity, and Sh is heat source term. This model can describe the energy transfer and mass transport process in the molten pool.

[0077] The weld spacing is optimized based on the relationship between the dynamic behavior of the molten pool and the weld spacing, the relationship between the mechanical properties of the welded joint and the weld spacing, and the heat and mass transport model of the molten pool. In this process, the weld spacing S can be determined to take into account the influence of the dynamic behavior of the molten pool on the welding quality, ensure the mechanical properties of the welded joint, and also consider the influence of the heat and mass transport of the molten pool on the welding process. Such a weld spacing optimization model helps to achieve a high-quality laser welding process and reduce the influence of adjacent welds during the welding process.

[0078] Example 3

[0079] This embodiment is to solve the problems of difficult assembly of existing stainless steel thin-walled parts and cylinder parts before welding, difficult to ensure weld quality during welding, and large deformation after welding, and provide a laser low-stress welding method for stainless steel thin-walled parts. It includes the following steps:

[0080] (1) Incoming material inspection: Check the incoming cylinder and corrugated plate materials separately to confirm that the quality meets the requirements;

[0081] (2) Cylinder assembly: The fixture is in place, and the cylinder is placed on the inner support fixture (the inner support fixture consists of four pieces). One end surface is used as the reference for positioning, and the other end is clamped. The center of the cylinder is used as the reference for positioning, and the inner support fixture is clamped, so as to achieve the purpose of positioning and clamping the cylinder.

[0082] In this step, the left end face of the cylinder is used as a reference for positioning; the inner support plate and the outer support are clamped with the center of the cylinder as a reference; and the right side external pressure support ring clamps the cylinder from the right side.

[0083] (3) Assembly of corrugated plate: Place the corrugated plate into the contoured tooling to constrain and fix the corrugated plate.

[0084] (4) Positioning and clamping the first corrugated plate: Install the combination of the profiling tooling and the corrugated plate on the surface of the cylinder, and use screws to lock the profiling tooling to position and clamp the first corrugated plate.

[0085] In this step, the positional relationship of the corrugated plate relative to the cylinder is transferred to the positional relationship of the profiling tooling relative to the cylinder, thereby positioning the corrugated plate; the corrugated plate is clamped by locking the profiling tooling with screws.

[0086] (5) Positioning and clamping the second corrugated plate: The positioner rotates 90°, and the combination of the profiling tooling and the second corrugated plate is installed on the surface of the cylinder. The profiling tooling is locked with screws to position and clamp the second corrugated plate. The principle of this step is the same as that of the specific step in step (4).

[0087] (6) Positioning and clamping the third corrugated plate: the positioner is rotated 90°, and the combination of the profiling tooling and the third corrugated plate is installed on the surface of the cylinder. The profiling tooling is locked with screws to clamp the third corrugated plate. The principle of this step is the same as that of the specific step in step (4).

[0088] (7) Positioning and clamping the fourth corrugated plate: the positioner is rotated 90°, and the combination of the profiling tooling and the fourth corrugated plate is installed on the surface of the cylinder. The profiling tooling is locked with screws to clamp the fourth corrugated plate. The principle of this step is the same as that of the specific step in step (4).

[0089] (8) Clamping support at the driven end: The tailstock at the driven end moves toward the tooling to clamp and support the welding tooling; the tailstock at the driven end clamps and supports the rotating tooling to increase the rigidity of the welding tooling.

[0090] (9) Welding of the first corrugated plate: Adjust the laser welding process parameters and weld the weld inside the first corrugated plate according to a specific welding trajectory (to ensure small welding heat impact and small deformation).

[0091] (10) Test piece welding and inspection: adjust the position of the laser welding head to the test piece welding operation area and weld the test piece; after the test piece welding is completed, send it for inspection; (the inspection frequency can be set independently)

[0092] (11) Inspection of laser welding head protective lens: After passing the inspection, check the laser welding head protective lens. If the lens is not obviously dirty, subsequent welding operations can be carried out. If the lens is obviously dirty, replace it; (the inspection frequency can be set independently)

[0093] (12) Welding of the second corrugated plate: The main drive positioner rotates 90°, adjusts the laser welding process parameters, and welds the weld inside the second corrugated plate according to a specific welding trajectory (ensuring small welding heat impact and small deformation);

[0094] (13) Test piece welding and inspection: adjust the position of the laser welding head to the test piece welding operation area, weld the test piece, and send it for inspection after the test piece welding is completed; (the inspection frequency can be set independently)

[0095] (14) Inspection of laser welding head protective lens: After passing the inspection, check the laser welding head protective lens. If the lens is not obviously dirty, the subsequent welding operation can be carried out. If the lens is obviously dirty, replace it; (the inspection frequency can be set independently);

[0096] (15) Welding of the third corrugated plate: The main drive positioner rotates 90°, adjusts the laser welding process parameters, and welds the weld inside the third corrugated plate according to a specific welding trajectory (ensuring small welding heat impact and small deformation);☆

[0097] (16) Test piece welding and inspection: adjust the position of the laser welding head to the test piece welding operation area, weld the test piece, and send it for inspection after the test piece welding is completed; (the inspection frequency can be set independently)

[0098] (17) Inspection of laser welding head protective lens: After passing the inspection, check the laser welding head protective lens. If the lens is not obviously dirty, subsequent welding operations can be carried out. If the lens is obviously dirty, replace it; (the inspection frequency can be set independently)

[0099] (18) Welding of the fourth corrugated plate: The main drive positioner rotates 90°, adjusts the laser welding process parameters, and welds the weld inside the fourth corrugated plate according to a specific welding trajectory (ensuring small welding heat impact and small deformation);

[0100] (19) Test piece welding and inspection: adjust the position of the laser welding head to the test piece welding operation area, weld the test piece, and send it for inspection after the test piece welding is completed; (the inspection frequency can be set independently)

[0101] (20) Inspection of laser welding head protective lens: After passing the inspection, check the laser welding head protective lens. If the lens is not obviously dirty, subsequent welding operations can be carried out. If the lens is obviously dirty, replace it; (the inspection frequency can be set independently)

[0102] (21) End: The welding process of the cylinder and the four corrugated plates is completed, and the welded parts enter the next process.

[0103] The flexible characteristics of the flexible welding tooling in this method step are reflected in:

[0104] ① The shape of the corrugated plate is an arc-shaped thin-walled part with a thickness of only 0.4mm. The stainless steel material has high elasticity, which makes it difficult for the corrugated plate to maintain an ideal shape. The rigid profiling tooling can correct and fix the corrugated plate with an actual shape and detect whether the incoming material is qualified. At this time, the profiling tooling plays the role of a mold and a checking fixture;

[0105] ② The inner support plate of the inner support fixture is of standard size, which can inspect the inner diameter of the cylinder and clamp the cylinder from the inside out. At this time, the profiling fixture plays the role of a checking fixture and a clamp;

[0106] ③ The combination of the profiling tooling and the corrugated plate is positioned and installed on the outer surface of the cylinder, and the position relationship of the corrugated plate relative to the cylinder is transferred to the position relationship of the profiling tooling relative to the cylinder, so as to position the corrugated plate, and the corrugated plate is clamped by locking the profiling tooling with screws. At this time, the profiling tooling plays the role of a gauge and a fixture;

[0107] ④ For workpieces with different diameters, the radius of the arc surface of the profiling plate can be quickly changed to adapt, and the radius size can be controlled by the stroke of the internal support mechanism.

[0108] Example 4

[0109] In this embodiment, a method for welding stainless steel thin-walled parts using a special welding heat source, quasi-continuous laser (QCW), is provided, thereby avoiding the welding defect problem caused by the difficulty in controlling the heat input of the traditional welding heat source. This heat source has many advantages in terms of heat source input control, and these advantages are mainly reflected in the following aspects:

[0110] ① High energy density and penetration: QCW lasers have high peak power and high energy density, which means they can achieve greater melting depth and stronger penetration in materials;

[0111] ②Stable welding process: The pulse welding method of QCW laser can avoid the influence of metal plume on laser absorption rate, making the welding process more stable and reducing the occurrence of defects such as spatter and explosion points, especially in thin plate welding.

[0112] ③ Molten pool stability: Due to the short action time of the QCW laser, the molten pool mainly exists evenly around the keyhole and is evenly stressed, so the incidence of defects such as pores, cracks, and spatter is relatively low.

[0113] ④ Small heat-affected zone: The intermittent action of the QCW laser on the material gives the material time to cool down, so the heat-affected zone and heat input are small, which is suitable for processing thin materials and materials close to heat-sensitive components.

[0114] ⑤High peak power: Compared with continuous lasers of the same average power, QCW lasers can achieve greater peak power;

[0115] ⑥Flexibility and compatibility: QCW lasers can be set to pulse mode or continuous mode. This flexibility enables a single laser to handle processing tasks that previously required two different lasers.

[0116] ⑦ Time domain pulse shaping: QCW laser can use time domain pulse shaping technology to provide gradient-varying pulse energy, which has a great effect on the welding of thin-walled materials.

[0117] ⑧Precision processing capability: The high pulse power characteristics of QCW lasers enable them to perform well in precision laser welding scenarios, especially in applications that require fine control of energy output.

[0118] Example 5

[0119] In this embodiment, a welding path planning method is provided, which is implemented by numerical simulation and emulation technology:

[0120] i. Temperature field and molten pool flow simulation: The temperature field distribution and molten pool flow during laser welding can be simulated by simulation software. These simulations help predict possible problems during welding, such as welding defects and the formation of heat-affected zones, thereby optimizing welding parameters and improving welding quality.

[0121] ii. Welding defect prediction and control: Numerical simulation technology can predict the defects that may occur during welding, such as pores, cracks, and spatter. Through simulation, researchers can analyze the formation mechanism of these defects and propose corresponding control strategies to improve welding quality.

[0122] iii. Microstructure evolution and residual stress analysis: Microstructure evolution and residual stress during laser welding have an important influence on the performance of the weld. Numerical simulation can help understand the evolution of these phenomena and provide theoretical support for reducing residual stress and optimizing weld structure.

[0123] iv. Heat source model development: In laser welding simulation, the heat source model is the key. By using models such as Gaussian surface heat source and double ellipsoid heat source, more accurate laser welding simulation can be achieved in simulation software such as ABAQUS and MSC.Marc.

[0124] v. Multi-physics coupling simulation: Laser welding is a complex process involving multiple physical fields such as heat, force, fluid, etc. Through multi-physics coupling simulation, various phenomena in the welding process, such as the dynamic behavior of the molten pool and the mechanical properties of the welded joint, can be more comprehensively understood and predicted.

[0125] In this embodiment, there are 240 welds, which are evenly distributed in four areas, with 60 welds in each area. The four areas are marked as A, B, C, and D in sequence. The welds in area A are marked as A1 to A60 in sequence, the welds in area B are marked as B1 to B60 in sequence, the welds in area C are marked as C1 to C60 in sequence, and the welds in area D are marked as D1 to D60 in sequence. The welding trajectory arrangement obtained by numerical simulation and simulation is as follows:

[0126] S1: A30 is the starting point of area A, B30 is the starting point of area B, C31 is the starting point of area C, and D31 is the starting point of area D. The welding path is:

[0127] [A30→C31→B30→D31]→[A29→C30→B29→D30]→[...]→[A1→C2→B1→D2]

[0128] S2: A31 is the starting point of area A, B31 is the starting point of area B, C32 is the starting point of area C, and D32 is the starting point of area D. The welding path is:

[0129] [A31→C32→B31→D32]→[...]→[A59→C60→B59→D60]→[A60→C1→B60→D1]

[0130] So far, 240 welds have been completed through two rounds of welding, S1 and S2.

[0131] The optimization of welding process parameters in this method is obtained by orthogonal test. By reasonably arranging the test conditions, the influence of multiple factors on the test results is evaluated with a small number of tests, and a better combination of laser welding process parameters is found. The factors that affect the welding quality during pulse laser welding are:

[0132] ① Laser power: This is one of the most basic parameters in the welding process and needs to be adjusted according to the thickness of the material and the welding requirements. The higher the power, the stronger the penetration ability, but it will also increase the heat affected zone.

[0133] ② Pulse frequency: The pulse frequency of the QCW laser will affect the stability of welding and the formation of the weld. Too high a frequency may result in inadequate welding, while too low a frequency may affect production efficiency.

[0134] ③ Pulse width: The pulse width determines the time the laser acts on the material and affects the depth and width of the weld. Wider pulses can provide more heat, but may also increase the heat-affected zone.

[0135] ④ Duty cycle: This is the ratio of pulse width to pulse period, which determines the proportion of time the laser emits laser per unit time, affecting the efficiency and quality of welding.

[0136] ⑤ Peak power: The peak power of QCW lasers is usually higher, which helps with material penetration and weld formation, especially when welding highly reflective materials.

[0137] ⑥Average power: The average power determines the total energy input during welding and needs to be adjusted according to the welding material and thickness.

[0138] ⑦ Defocus: Defocus refers to the distance between the laser focus and the workpiece surface. It will affect the focusing and energy distribution of the laser, and thus affect the welding effect.

[0139] ⑧Welding speed: The welding speed determines the residence time of the laser on the material. Too fast speed may lead to insufficient welding, while too slow speed will increase the heat affected zone.

[0140] ⑨ Waveform control: QCW laser can control the laser waveform through software to adapt to different welding requirements.

[0141] The orthogonal experimental method is designed as follows:

[0142] Step 1: Determine the factors and levels of the test. The main factors affecting welding quality are A laser power, B duty cycle (ratio of pulse width to pulse period), C defocus, D laser waveform, and E welding speed. The standard orthogonal test table L16 (4 5 ):

[0143] A:90W,120W,150W,180W; B:10,15,30,45; C:-1mm,-0.5mm,0.5mm,1mm; D:square wave,triangle wave,trapezoidal wave,exponential curve wave; E:4m / min,5m / min,6m / min,7m / min.

[0144] Step 2: Arrange the test plan:

[0145] L16(4 5 )

[0146]

[0147]

[0148] Step 3: Analysis of test results:

[0149] Through 16 groups of experiments, the best weld penetration depth was controlled at 0.8mm±0.1mm, ensuring that there is no weld penetration on the back and the welding penetration is guaranteed.

[0150] Step 4: Determine the local optimal welding process parameter combination:

[0151] Calculate the average index of each factor, determine the optimal level of each factor, and determine the main and secondary factors

[0152] Step 5: Determine the global optimal welding process parameter combination through multiple test approximation method.

[0153] Through the combination of the above methods: flexible welding tooling, optimal welding heat source, reasonable welding path planning and optimized welding process parameters, laser low-stress welding of stainless steel thin-walled parts can be achieved.

[0154] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A laser low-stress welding tool for stainless steel thin-walled parts, characterized in that: include: An internal support tool (1) is used to position, inspect and clamp the cylinder (4); An inner support fixture fixing module (2), the inner support fixture fixing module comprising a main drive positioner (21) and a driven end rotary support (22) arranged corresponding to the main drive positioner (21), the main drive positioner (21) and the driven end rotary support (22) both being provided with a three-jaw chuck (23) for clamping the inner support fixture (1); The corrugated plate assembly part (3) is used to constrain and fix the corrugated plate (5) and then be fixedly connected to the inner support tooling (1); A path planning module is used to plan the welding path according to the laser welding process parameters; The laser welding module is used to weld stainless steel thin-walled parts using quasi-continuous laser according to laser welding process parameters and welding paths.

2. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 1 is characterized in that: The inner support tooling (1) comprises an inner support main shaft (11), an inner support support seat (12), a plurality of radius-adjustable support members (13) arranged circumferentially along the cross section of the inner support main shaft (11) and movably connected to the inner support support seat (12), and an inner support driving member for driving the radius-adjustable support member (13) to move radially along the inner support main shaft (11), so that the circular cross section formed by the plurality of radius-adjustable support members (13) can be adjusted according to the radius design requirements of the cylinder (4); The inner support tooling (1) further comprises external pressure support rings (14) arranged at two axial ends of the inner support main shaft (11), wherein the external pressure support rings (14) are fixedly connected to the inner support main shaft (11).

3. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 1 is characterized in that: The inner support fixture fixing module (2) comprises a workbench (24), on which a slide rail is provided for the driven end rotary support (22) to move, and the slide rail is arranged along the axis of the inner support main shaft (11).

4. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 1 is characterized in that: The corrugated plate assembly (3) comprises an assembly body (31) and a plurality of restraining members (32) fixedly arranged on the assembly body (31), wherein the restraining member (32) is used to restrain a wave crest of the corrugated plate so that the shape of the wave crest meets the design requirements, and adjacent restraining members (32) are arranged at intervals to reserve a weld (6) for welding the corrugated plate (5).

5. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 4 is characterized in that: The corrugated plate assembly (3) also includes a plurality of external clamping fixtures (33) for fixing the assembly body (31) on the internal support fixture (1), and the external clamping fixture (33) includes a mounting surface fixing member arranged to fit the circumferential outer wall of the internal support fixture (1) and an external clamping mounting member corresponding to the mounting surface fixing member and used to fix the assembly body (31) on the mounting surface fixing member.

6. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 1 is characterized in that: The path planning module comprises: performing multi-physical field coupling simulation on the welding process according to laser welding process parameters to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process; constructing a weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate (5), and accordingly planning the welding paths of multiple linear welds arranged at intervals on multiple corrugated plates (5).

7. A stainless steel thin-wall laser low-stress welding tool according to claims 1-6, characterized in that: The laser welding module includes a quasi-continuous laser for welding.

8. A laser low stress welding method for stainless steel thin-walled parts, characterized in that: The following steps are involved: Step 1: Use the inner support fixture (1) to position, check and clamp the cylinder (4), and then drive the main drive positioner (21) and the driven end rotary support (22) to move to clamp the inner support fixture (1); Step 2: After the corrugated plate is constrained and fixed by the corrugated plate assembly (3), the positional relationship of the corrugated plate (5) relative to the cylinder (4) is converted into the positional relationship of the corrugated plate assembly (3) relative to the cylinder (4), thereby positioning the corrugated plate (5), and adjusting the rotation angle of the inner support tooling (1) according to the positioning, and the corrugated plate assembly (3) is fixedly connected to the inner support tooling (1), so as to complete the positioning and fixing of the corrugated plate (4) in sequence; Step three: according to the laser welding process parameters and welding path, the stainless steel thin-walled parts are welded using quasi-continuous laser.

9. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 8, characterized in that: The step 2 comprises the following steps: (201) designing the shape of the restraining member (32) and the spacing distance between adjacent restraining members (32) according to the shape of the corrugated plate, so that under the restraining action of the restraining member (32), the wave crest shape of the corrugated plate meets the design requirements, and at the same time, the spacing distance between adjacent restraining members (32) at least covers the weld to be processed; (202) The positional relationship of the corrugated plate (5) relative to the cylinder (4) is converted into the positional relationship of the corrugated plate assembly (3) relative to the cylinder (4), and according to the positional relationship, the first corrugated plate assembly (3) constrained by the corrugated plate (5) is installed on the inner support fixture (1), and then the inner support fixture (1) is rotated to a specified angle to install the next corrugated plate assembly (3) constrained by the corrugated plate (5), until all the corrugated plate assembly (3) constrained by the corrugated plate (5) are installed.

10. The laser low-stress welding tool for stainless steel thin-walled parts according to claim 7, characterized in that: The step three comprises the following steps: (301) According to the laser welding process parameters, multi-physics field coupling simulation is performed on the welding process to predict the dynamic behavior of the molten pool and the mechanical properties of the welded joint during the welding process; (302) constructing a weld spacing optimization model that comprehensively considers the dynamic behavior of the molten pool and the mechanical properties of the welded joint, so as to obtain the optimal weld spacing between two adjacent welding processes on the same corrugated plate (5), and thereby plan the welding paths of multiple linear welds arranged at intervals on multiple corrugated plates (5); (303) sequentially laser processing the first weld seam of each corrugated plate (5) until the first weld seam processing of all the corrugated plates (5) is completed; (304) processing the second weld of each corrugated plate (5) in sequence according to the optimal weld spacing between two adjacent welding steps of each corrugated plate (5) until the second welds of all the corrugated plates (5) are processed; (305) Repeat step (304) until all welds on all corrugated plates (5) are processed.

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