A back of weld follow-up protection device for laser splice welding of automobile variable thickness plates

Abstract

The present application relates to the technical field of automobile parts manufacturing, in particular to a welding seam back following protection device for laser splicing welding of automobile variable-thickness plates, comprising a machine table, a laser welding gun and a moving table slidingly assembled on the machine table, the laser welding gun is fixedly arranged above the machine table, and the moving table is used for supporting the automobile variable-thickness plate to be welded. The present application sets a floating mechanism, uses a thickness measuring roller to realize real-time sensing of the thickness change of the automobile variable-thickness plate, and drives a protection nozzle to make corresponding vertical lifting movement in linkage, so that the distance between the protection nozzle and the bottom surface of the plate can be kept constant during the whole welding process. The technical problems that the traditional fixed nozzle is prone to collision or air flow impact on the molten pool when welding thick plates, and the protection effect is reduced when welding thin plates, resulting in oxidation of the molten pool, are effectively solved, and stable and reliable protection gas coverage of the welding seam back in different plate thickness areas is ensured.

Description

Technical Field

[0001] This invention relates to the field of automotive parts manufacturing technology, and in particular to a follow-up protection device for the back side of the weld seam in laser splicing of automotive variable thickness plates. Background Technology

[0002] Laser-welded sheet metal technology is one of the core processes for automotive lightweighting. By laser-welding steel sheets of different thicknesses, strengths, or materials together into a single sheet, which is then stamped into body structural components, vehicle weight can be effectively reduced while ensuring collision safety. This technology has been widely used in components such as door rings, longitudinal beams, and floor tunnels.

[0003] For laser-welded plates of the same thickness or with small thickness differences, traditional processes are relatively mature—using a back-side protection nozzle with a fixed gap can achieve good back-side protection of the weld and ensure welding quality. However, with the increasing requirements for lightweighting, components such as door rings often directly splice thick plate areas (e.g., 1.6mm) with thin plate areas (e.g., 1.0mm), resulting in a continuously increasing thickness ratio and a significant increase in the difficulty of splicing.

[0004] In laser welding, the protection of the back side of the weld is a key factor in ensuring weld quality. Shielding gas prevents oxidation of the high-temperature molten pool from contact with air, while also helping to improve weld formation and reduce defects such as spatter and porosity. For conventional welds with uniform thickness, a fixed back protection nozzle can meet the requirements by setting a reasonable nozzle-to-plate bottom distance. However, for laser welds with large thickness ratios, there is a significant difference in plate thickness on both sides of the weld, with a bottom height difference of over 0.6 mm. Traditional fixed nozzles cannot simultaneously accommodate the protection distances on both sides. If the gap is set according to the thicker plate side, the nozzle on the thinner plate side is too far from the plate bottom, causing the shielding gas to be diluted by ambient air, significantly increasing the risk of molten pool oxidation. If the gap is set according to the thinner plate side, the nozzle on the thicker plate side is too close to the plate bottom, potentially colliding with it, and the vertically jetted gas may impact the molten pool, causing spatter. This contradiction makes fixed back protection devices unsuitable for the stable production requirements of laser welds with large thickness ratios. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a back-side protection device for laser splicing of automotive variable thickness plates, so as to solve the technical problem that the fixed back-side protection nozzle in the prior art cannot adapt to the thickness change of automotive variable thickness plates, resulting in unstable back-side protection effect of the weld.

[0006] To achieve the above objectives, the present invention provides a back-side protection device for laser welding of automotive variable thickness plates, comprising a machine base, a laser welding torch, and a movable stage slidably mounted on the machine base. The laser welding torch is fixedly disposed above the machine base, and the movable stage is used to support the automotive variable thickness plate to be welded. The device also includes:

[0007] A drive assembly mounted on the machine base is used to drive a moving table carrying an automotive variable thickness plate to move toward the laser welding gun.

[0008] A positioning component located on a moving platform is used to clamp and fix two variable thickness plates to be spliced ​​and welded according to the width of the automotive variable thickness plate.

[0009] A protective nozzle is mounted on a moving platform and located directly below the laser welding gun. A floating mechanism is provided between the protective nozzle and the nozzle of the laser welding gun. The floating mechanism is used to sense the thickness change of the automotive variable thickness plate during the welding process and adjust the vertical distance between the protective nozzle and the bottom of the automotive variable thickness plate according to the thickness change.

[0010] Preferably, the driving component includes:

[0011] A first motor is fixedly installed on the machine base. The output shaft of the first motor is fixedly connected to a lead screw, and one end of the lead screw is rotatably installed on the machine base through a bearing.

[0012] An extension plate is fixed to the lower end of the moving platform, and the extension plate is threadedly mounted on the lead screw;

[0013] And guide rails fixedly installed on both sides of the machine platform, with sliding blocks slidably installed on the guide rails, the top of which is fixed to the bottom of the moving platform.

[0014] Preferably, the positioning component includes:

[0015] A second motor is fixedly installed on one side of the top of the mobile platform, and the output shaft of the second motor is fixedly connected to a bidirectional threaded rod.

[0016] A pair of symmetrically threaded clamps are installed at both ends of the surface of the bidirectional threaded rod, and a guide rod is slidably installed between the bottoms of the two clamps via a sliding sleeve. The two ends of the guide rod are fixed to the moving platform.

[0017] Two brackets are symmetrically fixed to the surface of the moving platform. Each clamp is located at the end of a corresponding bracket and is used to clamp and position the end of the variable thickness plate after it is placed on the bracket.

[0018] Preferably, the floating mechanism includes:

[0019] A mounting bracket that can be detachably installed on the laser welding gun, the mounting bracket being horizontally arranged on the laser welding gun;

[0020] The movable frame is mounted on the mounting bracket, and the bottom of the movable frame has ball bearings, which provide rolling support to the surface of the movable platform.

[0021] An assembly slot is provided at the lower end of the movable frame, and a connecting plate is fixed at the upper end of the assembly slot;

[0022] A movable rod is vertically inserted through the connecting plate, and a thickness measuring roller is installed at the bottom of the movable rod. The bottom of the thickness measuring roller abuts against the side edge of the bracket.

[0023] A first spring is sleeved on the movable rod, with its two ends abutting against the bottom surface of the connecting plate and the top surface of the thickness measuring roller, respectively.

[0024] A connecting rod extends through one side of the connecting plate, and the top of the connecting rod is fixedly connected to the top of the movable rod;

[0025] A guide sleeve fixed to the bottom of the connecting rod and a pull rod that slides horizontally through the middle of the guide sleeve; the lower end of the pull rod is slidably mounted on the surface of the moving platform along the moving direction of the moving platform.

[0026] A U-shaped sleeve is fixed to the pull rod and close to one end of the laser welding gun. The protective nozzle is installed inside the U-shaped sleeve, and the air outlet of the protective nozzle faces the bottom of the automotive variable thickness plate.

[0027] And an adjustment component disposed between the protective nozzle and the U-shaped sleeve, the adjustment component being used to adjust the blowing angle of the protective nozzle accordingly when the U-shaped sleeve floats up and down.

[0028] Preferably, the connecting plate has through holes on both sides, and the inner wall of the through holes has a plurality of first grooves equidistantly spaced along the circumference. A first ball is rolled in the first groove, and one side of the first ball rolls against the surface of the corresponding movable rod or connecting rod.

[0029] Preferably, the floating mechanism further includes:

[0030] Two T-shaped rods symmetrically fixed to the bottom of the pull rod and a slider slidably sleeved on each of the T-shaped rods;

[0031] Two symmetrical sliding grooves are formed through the surface of the moving platform, and the slider is slidably installed in the corresponding sliding groove;

[0032] And a second spring sleeved on the lower end of the T-shaped rod, the two ends of the second spring being fixed between the bottom surface of the slider and the bottom end of the T-shaped rod, respectively.

[0033] Preferably, the adjustment component includes:

[0034] Pins are symmetrically fixed on both sides of the middle part of the protective nozzle, and the pins are rotatably installed on the inner wall of the U-shaped sleeve;

[0035] A connecting block fixed to the inner wall of the U-shaped sleeve;

[0036] A pressure rod is vertically and movably inserted through the middle of the connecting block, with the bottom of the pressure rod abutting against the surface of the moving platform;

[0037] A connecting plate fixedly installed in the middle of the pressure bar;

[0038] A third spring is sleeved on the pressure rod, and the two ends of the third spring abut against the bottom surface of the connecting block and the top surface of the connecting plate, respectively;

[0039] Two pairs of sliding grooves are respectively opened opposite to each other on the inner walls of both sides of the U-shaped sleeve;

[0040] A sliding block is slidably installed in each of the sliding grooves, and a positioning pin is fixed on the sliding block;

[0041] A first hinge rod, with its two ends respectively hinged to the top of the connecting plate and the corresponding positioning pin;

[0042] A second hinge rod, one end of which is hinged to the positioning pin;

[0043] A third hinge rod is hinged to the other end of the second hinge rod, wherein two of the third hinge rods located near the protective nozzle are fixedly installed on the lower outer wall of the protective nozzle;

[0044] And a guide plate fixedly installed between the two third hinge rods on the side away from the protective nozzle. The middle two sides of the guide plate are hinged to the inner wall of the U-shaped sleeve. When the U-shaped sleeve is raised and lowered, the connecting plate moves vertically, driving the sliding block at one end of the first hinge rod to slide in the sliding groove. Then, through the second and third hinge rods, the protective nozzle and the guide plate are driven to deflect relative to each other around their respective hinge axes, so as to change the blowing angle of the protective nozzle.

[0045] Preferably, the upper end of the pressure rod is fixed with two limiting rings at intervals along its axial direction, and the two limiting rings are used to limit the vertical movement of the pressure rod relative to the connecting block.

[0046] Preferably, the protection device further includes a flow regulating component disposed inside the protection nozzle, the flow regulating component being used to change the outlet air flow rate according to the deflection action of the protection nozzle, the flow regulating component including:

[0047] A piston rod that is movable and passes through the lower end of the protective nozzle;

[0048] A stopper disc is fixed to one end of the piston rod located inside the protective nozzle, and the stopper disc is sealed and fitted to the inner wall of the protective nozzle;

[0049] A conical valve core fixed to the top of the plug disc;

[0050] A ball fixed to the bottom end of the piston rod, the diameter of the ball being larger than the diameter of the piston rod;

[0051] A fourth spring is sleeved on the lower end of the piston rod, with its two ends abutting against the bottom surface of the protective nozzle and the surface of the ball, respectively.

[0052] And a pressure block fixedly installed on the surface of the moving platform, wherein the side of the pressure block near the protective nozzle is provided with an inclined surface that cooperates with the ball, so that when welding to the thin area of ​​the automotive variable thickness plate, the U-shaped sleeve drives the protective nozzle to descend, causing the ball to squeeze the inclined surface of the pressure block, thereby pushing the piston rod and the conical valve core to move upward, so as to reduce the air flow rate of the protective nozzle blowing port.

[0053] Preferably, the floating mechanism further includes:

[0054] A connecting sleeve is fixed to the top of the movable frame, and the connecting sleeve is slidably mounted on the surface of the mounting frame;

[0055] Multiple adjustment holes are equidistantly provided on the surface of the mounting bracket along the vertical direction;

[0056] A U-shaped mounting block fixed to the top of the connecting sleeve;

[0057] A locking pin is inserted vertically through the U-shaped mounting block and the connecting sleeve, with the lower end of the locking pin inserted into a corresponding adjustment hole;

[0058] And a fifth spring sleeved on the locking pin, the two ends of the fifth spring respectively abutting against the top wall of the U-shaped mounting block and the top surface of the connecting sleeve.

[0059] The beneficial effects of this invention are as follows: The weld back-side protection device for laser welding of automotive variable thickness plates, based on this invention, utilizes a floating mechanism and a thickness-measuring roller to sense the thickness changes of the automotive variable thickness plate in real time. This mechanism then drives the protective nozzle to perform corresponding vertical lifting and lowering movements, ensuring that the distance between the protective nozzle and the bottom surface of the plate remains constant throughout the welding process. This effectively solves the technical problems of traditional fixed nozzles, which are prone to collisions or gas flow impacts on the molten pool when welding thick plates, and the reduced protective effect leading to molten pool oxidation when welding thin plates. It ensures that the back of the weld receives stable and reliable protective gas coverage in different plate thickness areas, thereby significantly improving the mechanical properties and appearance quality of the laser-welded joint.

[0060] By incorporating an adjustment mechanism, the protective nozzle and guide vane are driven to deflect relative to each other around their respective hinge axes as the U-shaped sleeve rises and falls with changes in plate thickness. When welding thin plate areas, the protective nozzle descends, allowing the protective gas to be blown towards the bottom of the weld at a gentler angle, avoiding vertical impact on the high-temperature molten pool that could cause spatter. When welding thick plate areas, the protective nozzle rises, restoring a larger angle to provide wide-area coverage. This adaptive angle adjustment function significantly enhances the matching ability of the protective airflow to areas of different plate thicknesses, further reducing the probability of defects such as porosity and spatter.

[0061] By setting up a flow regulation component, the interaction between the protective nozzle and the inclined surface of the pressure block during the follow-up lifting and lowering of the nozzle drives the conical valve core to automatically adjust the nozzle outlet cross-sectional area. When welding thick plate areas, the ventilation cross-section is automatically increased to provide a larger protective airflow to meet the protection requirements of wide welds; when welding thin plate areas, the ventilation cross-section is automatically reduced to avoid gas waste and prevent molten pool disturbance caused by excessive airflow impact in thin plate areas.

[0062] By eliminating all electronic control components through a mechanical follow-up structure, the equipment manufacturing cost is reduced by about 70%, and the overall assembly volume is reduced by more than 50%. At the same time, the interference of high-power laser welding electromagnetic field on electronic control equipment is avoided, the working stability is greatly improved, and only conventional mechanical wear parts need to be maintained, resulting in a significant reduction in the total life cycle cost. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a three-dimensional structural diagram of the present invention;

[0065] Figure 2 This is a bottom view in this invention;

[0066] Figure 3 This is a front view schematic diagram of the present invention;

[0067] Figure 4 for Figure 3 Enlarged schematic diagram of the structure at point A in the middle;

[0068] Figure 5 This is a partial structural diagram of the movable stage, protective nozzle, and mounting frame in this invention.

[0069] Figure 6 This is a schematic cross-sectional view of a portion of the structure of the moving stage, protective nozzle, and mounting frame in this invention.

[0070] Figure 7 for Figure 6 Enlarged schematic diagram of the structure at point B;

[0071] Figure 8 for Figure 6 Enlarged schematic diagram of the structure at point C;

[0072] Figure 9 for Figure 6 Enlarged schematic diagram of the structure at point D;

[0073] Figure 10 This is a partial structural cross-sectional view of the protective nozzle, pressure rod, and air guide plate in this invention.

[0074] The diagram is marked as follows:

[0075] 1. Machine base; 2. Laser welding gun; 3. Moving table; 301. Bracket; 4. Protective nozzle; 5. First motor; 6. Lead screw; 7. Second motor; 8. Bidirectional threaded rod; 9. Fixture; 10. Guide rod; 11. Mounting frame; 12. Moving frame; 13. Movable rod; 14. Thickness measuring roller; 15. First spring; 16. Connecting rod; 17. Guide sleeve; 18. Pull rod; 19. U-shaped sleeve; 20. T-shaped rod; 21. Slider; 22. Slider 23. Groove; 24. Second spring; 25. Connecting block; 26. Pressure rod; 27. Connecting plate; 28. Third spring; 29. ​​Sliding groove; 30. Sliding block; 31. First hinge rod; 32. Second hinge rod; 33. Third hinge rod; 34. Air guide plate; 35. Piston rod; 36. Plug disc; 37. Conical valve core; 38. Fourth spring; 39. Pressure block; 40. Adjusting hole; 41. U-shaped mounting block; 42. Locking pin; 43. Fifth spring. Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0077] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0078] In a first aspect, the present invention provides a follow-up protection device for the back side of the weld in laser splicing of automotive variable thickness plates, such as... Figure 1-10 As shown, the system includes a machine base 1, a laser welding torch 2, and a movable stage 3 slidably mounted on the machine base 1. The laser welding torch 2 is fixedly mounted above the machine base 1, and the movable stage 3 is used to support the automotive variable thickness plate to be welded. The system also includes:

[0079] The drive assembly is installed on the machine base 1. The drive assembly is used to drive the moving table 3 carrying the automotive variable thickness plate to move toward the laser welding gun 2.

[0080] The positioning component located on the moving stage 3 is used to clamp and fix the two variable thickness plates to be spliced ​​and welded according to the width of the automotive variable thickness plate.

[0081] A protective nozzle 4 is positioned on the moving stage 3 and directly below the laser welding torch 2. A floating mechanism is installed between the protective nozzle 4 and the nozzle of the laser welding torch 2. This floating mechanism senses the thickness changes of the automotive variable-thickness plate during welding and adjusts the vertical distance between the protective nozzle 4 and the bottom of the plate accordingly. An inert gas supply pipe is connected to one side of the protective nozzle 4 via a connecting pipe, continuously supplying welding shielding gases such as argon to provide a gas source for protecting the back of the weld.

[0082] In this embodiment: the driving component includes:

[0083] A first motor 5 is fixedly installed on the machine base 1. The output shaft of the first motor 5 is fixedly connected to a lead screw 6, and one end of the lead screw 6 is rotatably installed on the machine base 1 through a bearing.

[0084] An extension plate is fixed to the lower end of the moving platform 3, and the extension plate is threadedly installed on the lead screw 6;

[0085] The machine tool 1 is equipped with guide rails fixedly installed on both sides, and sliding blocks with their tops fixed to the bottom of the moving table 3 are slidably installed on the guide rails. When the first motor 5 is started during plate welding, the lead screw 6 rotates, driving the moving table 3 and the workpiece on it to move relative to the fixed laser welding gun 2, thereby realizing welding feed.

[0086] In this embodiment: the positioning component includes:

[0087] A second motor 7 is fixedly installed on one side of the top of the mobile platform 3, and the output shaft of the second motor 7 is fixedly connected to a bidirectional threaded rod 8.

[0088] A pair of symmetrically threaded clamps 9 are installed at both ends of the surface of the bidirectional threaded rod 8, and a guide rod 10 is slidably installed between the bottoms of the two clamps 9 via a sliding sleeve. The two ends of the guide rod 10 are fixed on the moving table 3.

[0089] Two brackets 301 are symmetrically fixed to the surface of the moving table 3. Each clamp 9 is located at the end of a corresponding bracket 301 and is used to clamp and position the end of the automotive variable thickness plate after it is placed on the bracket 301. After the plate end is clamped and fixed to the bracket 301 by the clamp 9, when the second motor 7 drives the bidirectional threaded rod 8 to rotate, the two clamps 9 will move closer or further away synchronously, thereby adjusting the position according to the width of the variable thickness plate to be welded.

[0090] In this embodiment: the floating mechanism includes:

[0091] A mounting bracket 11 is detachably mounted on the laser welding gun 2, and the mounting bracket 11 is horizontally arranged on the laser welding gun 2;

[0092] The movable frame 12 is mounted on the mounting bracket 11. The bottom of the movable frame 12 has ball bearings, and the bottom of the movable frame 12 is supported on the surface of the movable table 3 by the ball bearings.

[0093] An assembly slot is provided at the lower end of the movable frame 12, and a connecting plate is fixed at the upper end of the assembly slot;

[0094] A movable rod 13 is vertically mounted on the connecting plate. A thickness-measuring roller 14 is installed at the bottom of the movable rod 13, and the bottom of the thickness-measuring roller 14 abuts against the side edge of the bracket 301. The thickness-measuring roller 14 is directly opposite the side edge of the plate at the weld joint position and is horizontally aligned with the welding point of the laser welding gun 2. It detects the real-time thickness of the plate at the welding position, ensuring that the detection data is completely synchronized with the welding area. When the variable thickness plate is placed on the bracket 301, the side edge of the plate will press down on the thickness-measuring roller 14, causing the movable rod 13 to move upward and the first spring 15 to be compressed. In this way, the thickness-measuring roller 14 always maintains contact with the side edge of the plate, and its vertical position accurately reflects the plate thickness at that point.

[0095] The first spring 15 is sleeved on the movable rod 13, and the two ends of the first spring 15 abut against the bottom surface of the connecting plate and the top surface of the thickness measuring roller 14, respectively.

[0096] The connecting rod 16 runs through one side of the connecting plate, and the top of the connecting rod 16 is fixedly connected to the top of the movable rod 13. Since the movable rod 13 and the connecting rod 16 are rigid synchronous lifting structures, the vertical lifting displacement of the protective nozzle 4 is matched with the thickness change of the automotive variable thickness plate in a 1:1 ratio through the lever ratio matching design, and the preset constant distance between the protective nozzle and the bottom surface of the plate is maintained throughout the process.

[0097] The guide sleeve 17 is fixed to the bottom of the connecting rod 16 and the pull rod 18 is slidably inserted through the middle of the guide sleeve 17 in the horizontal direction. The lower end of the pull rod 18 is slidably installed on the surface of the moving platform 3 along the moving direction of the moving platform 3. The ball bearings at the bottom of the moving frame 12 enable horizontal resistance-free sliding. The horizontal sliding cooperation between the guide sleeve 17 and the pull rod 18 can compensate for the horizontal displacement deviation of the device, eliminate structural interference during the follow-up lifting process, and ensure that the vertical follow-up action is accurately and independently executed.

[0098] A U-shaped sleeve 19 is fixed to the pull rod 18 and is close to one end of the laser welding gun 2. The protective nozzle 4 is installed inside the U-shaped sleeve 19, and the air outlet of the protective nozzle 4 faces the bottom of the automotive variable thickness plate.

[0099] And an adjustment component is provided between the protective nozzle 4 and the U-shaped sleeve 19. The adjustment component is used to adjust the blowing angle of the protective nozzle 4 accordingly when the U-shaped sleeve 19 floats up and down.

[0100] In laser welding of automotive variable thickness plates, when the moving stage 3 carries the variable thickness plate and moves it downwards towards the laser welding gun 2, the thickness measuring roller 14 contacts the edge of the plate in real time. When the plate thickness decreases, the thickness measuring roller 14 moves downwards (relative to the moving frame 12) under the action of the first spring 15, causing the movable rod 13, connecting rod 16, and guide sleeve 17 to move downwards together. The descent of the guide sleeve 17 forces the pull rod 18, U-shaped sleeve 19, and protective nozzle 4 to move downwards as a whole, thereby reducing the distance between the protective nozzle 4 and the bottom surface of the plate. Conversely, if the plate thickness increases, the thickness measuring roller 14 is lifted, causing the protective nozzle 4 to rise through the linkage mechanism, increasing the distance. By setting a reasonable lever ratio (i.e., the ratio of the horizontal distance between the movable rod 13 and the connecting rod 16 to the horizontal distance from the connecting rod 16 to the protective nozzle 4), the displacement of the protective nozzle 4 can be matched with the change in plate thickness, achieving constant gap follow-up protection. This effectively solves the technical problems of traditional fixed nozzles being prone to collisions or airflow impacts on the molten pool when welding thick plates, and the reduced protection effect leading to oxidation of the molten pool when welding thin plates. It ensures that the back of the weld can obtain stable and reliable protective gas coverage in different plate thickness areas, thereby significantly improving the mechanical properties and appearance quality of the laser welded joint.

[0101] In this embodiment: perforations are provided on both sides of the connecting plate, and multiple first grooves are provided at equal intervals along the circumference on the inner wall of the perforations. First balls are rolled in the first grooves, and one side of the first ball rolls against the surface of the corresponding movable rod 13 or connecting rod 16.

[0102] In this embodiment, the floating mechanism further includes:

[0103] Two T-shaped rods 20 are symmetrically fixed to the bottom of the pull rod 18, and a slider 21 is slidably sleeved on each T-shaped rod 20. Specifically, the inner wall of the slider 21 is provided with multiple second grooves at equal intervals along the circumference, and second balls are rolled in the second grooves. The second balls roll and abut against the surface of the T-shaped rod 20. Through the first ball in the inner wall of the connecting plate through the hole and the second ball in the inner wall of the slider 21, the mechanical friction of the moving rod, connecting rod and T-shaped rod during the sliding process can be eliminated, ensuring smooth lifting and sliding without jamming, and improving the adaptive adjustment accuracy.

[0104] Two symmetrical grooves 22 are symmetrically opened through the surface of the moving stage 3, and the slider 21 is slidably installed in the corresponding groove 22;

[0105] A second spring 23 is fitted onto the lower end of the T-shaped rod 20, with its two ends fixed between the bottom surface of the slider 21 and the bottom end of the T-shaped rod 20, respectively. This allows the pull rod 18 to not only move up and down with the guide sleeve 17, but also to be constrained in the horizontal direction, ensuring that the U-shaped sleeve 19 and the protective nozzle 4 can accurately rise and fall with the thickness measuring roller 14 while moving with the moving table 3.

[0106] In this embodiment: the adjustment component includes:

[0107] Pins are symmetrically fixed on both sides of the middle part of the protective nozzle 4, and the pins are rotatably installed on the inner wall of the U-shaped sleeve 19;

[0108] Connecting block 24 fixed to the inner wall of U-shaped sleeve 19;

[0109] A pressure rod 25 is vertically and movably inserted through the middle of the connecting block 24, and the bottom of the pressure rod 25 abuts against the surface of the moving table 3;

[0110] A connecting plate 26 is fixedly installed in the middle of the pressure bar 25;

[0111] A third spring 27 is sleeved on the pressure rod 25, and the two ends of the third spring 27 abut against the bottom surface of the connecting block 24 and the top surface of the connecting plate 26, respectively.

[0112] Two pairs of sliding grooves 28 are respectively opened on the inner walls of both sides of the U-shaped sleeve 19;

[0113] A sliding block 29 is slidably installed in each sliding groove 28, and a positioning pin is fixed on the sliding block 29;

[0114] The first hinge rod 30 is hinged at both ends to the top of the connecting plate 26 and the corresponding positioning pin;

[0115] A second hinge rod 31, one end of which is hinged to a positioning pin;

[0116] A third hinge rod 32 is hinged to the other end of the second hinge rod 31, wherein two third hinge rods 32 located on the side near the protective nozzle 4 are fixedly installed on the lower outer wall of the protective nozzle 4.

[0117] And a guide plate 33 is fixedly installed between two third hinge rods 32 on the side away from the protective nozzle 4. The middle two sides of the guide plate 33 are hinged to the inner wall of the U-shaped sleeve 19 so that when the U-shaped sleeve 19 is raised and lowered, the connecting plate 26 moves vertically, driving the sliding block 29 at one end of the first hinge rod 30 to slide in the sliding groove 28. Then, through the second hinge rod 31 and the third hinge rod 32, the protective nozzle 4 and the guide plate 33 are driven to deflect relative to each other around their respective hinge axes, so as to change the blowing angle of the protective nozzle 4.

[0118] As the U-shaped sleeve 19 descends, the bottom of the pressure rod 25 presses against the surface of the moving platform 3, causing the pressure rod 25 to move upward relative to the U-shaped sleeve 19, compressing the third spring 27 and driving the connecting plate 26 to move upward. The connecting plate 26 pushes the sliding block 29 to slide within the sliding groove 28 on the inner wall of the U-shaped sleeve 19 via the first hinge rod 30. The positioning pin on the sliding block 29 causes the second hinge rod 31 to deflect, which in turn drives the protective nozzle 4 to deflect around its central pin shaft via the third hinge rod 32 (simultaneously, the third hinge rod 32 on the other side causes the air guide plate 33 to deflect). When welding thin plates (when the plate thickness decreases), the U-shaped sleeve 19 descends with the plate thickness, and the pressure rod 25 moves upward relative to the U-shaped sleeve, driving the connecting plate 26 to move upward. Through the first hinge rod 30, the sliding block 29 is pushed to slide inward along the sliding groove 28, which in turn moves the second hinge rod 31 and the third hinge rod 32, causing the protective nozzle 4 to tilt downward and the air guide plate 33 to tilt in the opposite direction at the same time, so that the protective gas is blown towards the back of the weld at a gentle tilt angle, avoiding vertical impact on the molten pool.

[0119] When welding thick plates (as the plate thickness increases), the U-shaped sleeve 19 rises with the plate thickness, the pressure rod 25 moves downwards relative to it, the third spring 27 resets, driving each hinge rod to move in the opposite direction, the protective nozzle 4 returns to a near-vertical blowing angle, and the air guide plate 33 flips and resets, avoiding obstruction of airflow and achieving wide-area gas coverage. This adaptive angle adjustment function significantly enhances the matching ability of the protective airflow to areas with different plate thicknesses, further reducing the probability of defects such as porosity and spatter.

[0120] In this embodiment, two limiting rings are fixed at the upper end of the pressure rod 25 along its axial direction. The two limiting rings are used to limit the vertical movement of the pressure rod 25 relative to the connecting block 24.

[0121] In this embodiment: the protection device further includes a flow regulating component disposed inside the protection nozzle 4. The flow regulating component is used to change the outlet air flow rate according to the deflection action of the protection nozzle 4. The flow regulating component includes:

[0122] The piston rod 34 is movable and passes through the lower end of the protective nozzle 4;

[0123] A stopper disc 35 is fixed to one end of the piston rod 34 inside the protective nozzle 4. The stopper disc 35 is sealed and fitted with the inner wall of the protective nozzle 4. During the movement of the stopper disc 35, it is always sealed and fitted with the inner wall of the nozzle, ensuring that there is no air leakage during the up and down movement of the valve core, and that the flow rate adjustment is precise and controllable.

[0124] A conical valve core 36 is fixed to the top of the plug disc 35;

[0125] A ball fixed to the bottom end of the piston rod 34, the diameter of the ball being larger than the diameter of the piston rod 34;

[0126] A fourth spring 37 is sleeved on the lower end of the piston rod 34, and the two ends of the fourth spring 37 abut against the bottom surface of the protective nozzle 4 and the surface of the ball, respectively.

[0127] And a pressure block 38 fixedly installed on the surface of the moving platform 3. The side of the pressure block 38 near the protective nozzle 4 is provided with an inclined surface that cooperates with the ball. When welding to the thin area of ​​the automotive variable thickness plate, the U-shaped sleeve 19 drives the protective nozzle 4 to descend, so that the ball squeezes the inclined surface of the pressure block 38, thereby pushing the piston rod 34 and the conical valve core 36 to move upward, so as to reduce the air flow of the air blowing port of the protective nozzle 4.

[0128] As the welding thin plate area and the protective nozzle 4 descend, the deflection of the protective nozzle 4 causes the ball at the bottom of the nozzle 4 to gradually contact and press against the inclined surface of the pressure block 38. This pushes the piston rod 34 and the plug disc 35 upward, causing the conical valve core 36 to rise and gradually block the nozzle outlet, reducing the gas outlet cross-section and automatically decreasing the gas flow rate. Conversely, the same applies when the thickness increases. This achieves the following: as the thickness increases, the ventilation cross-section increases, and the protective gas flow rate automatically increases to adapt to the larger protection range required for thicker plates; as the thickness decreases, the action is reversed, the protective head moves upward, and the gas valve closes slightly, reducing gas waste and preventing splashing caused by airflow impact in the thin plate area. By eliminating all electrical control components through the mechanical follow-up structure, the equipment manufacturing cost is reduced by approximately 70%, and the overall assembly volume is reduced by more than 50%. At the same time, it avoids the interference of the electromagnetic field of high-power laser welding on the electrical control equipment, significantly improving operational stability. Moreover, it only requires maintenance of conventional mechanical wear parts, significantly reducing the total life cycle cost.

[0129] In this embodiment, the floating mechanism further includes:

[0130] A connecting sleeve is fixed to the top of the movable frame 12, and the connecting sleeve is slidably mounted on the surface of the mounting frame 11;

[0131] Multiple adjustment holes 39 are equidistantly provided on the surface of the mounting bracket 11 along the vertical direction;

[0132] U-shaped mounting block 40 fixed to the top of the connecting sleeve;

[0133] A locking pin 41 vertically penetrates the U-shaped mounting block 40 and the connecting sleeve, with the lower end of the locking pin 41 inserted into a corresponding adjustment hole 39;

[0134] And a fifth spring 42 sleeved on the locking pin 41, with the two ends of the fifth spring 42 abutting against the top wall of the U-shaped mounting block 40 and the top surface of the connecting sleeve, respectively.

[0135] During operation, the operator pulls up the locking pin 41, compressing the fifth spring 42, causing the lower end of the locking pin 41 to exit from the current adjustment hole 39. Then, the connecting sleeve is slid horizontally to move the moving frame 12 horizontally relative to the mounting frame 11. Since the thickness measuring roller 14 is installed at the lower end of the moving frame 12, this horizontal displacement will directly change the horizontal distance between the thickness measuring roller 14 and the side edge of the plate on the moving table 3. For plates with a larger width and varying thickness, whose side edges are closer to the outside of the moving table 3, the moving frame 12 needs to be adjusted horizontally away from the laser welding gun 2 to extend the thickness measuring roller 14 outward, ensuring that it can stably press on the side edge of the plate. For plates with a smaller width and varying thickness, the moving frame 12 is adjusted horizontally towards the laser welding gun 2 to retract the thickness measuring roller 14 inward, avoiding interference with the edge of the plate or exceeding the plate's range. After adjustment, release the locking pin 41. Under the elastic force of the fifth spring 42, the lower end of the locking pin 41 will automatically insert into the corresponding adjustment hole 39, thus completing the locking.

[0136] It should be noted that, since the guide sleeve 17 is horizontally slidably fitted onto the tie rod 18, the moving frame 12 achieves horizontal position adjustment through the connecting sleeve, adapting to automotive variable thickness plates of different widths. After width positioning is completed, it is locked and fixed by the locking pin 41. The guide sleeve 17 at the bottom of the connecting rod 16 and the tie rod 18 have a horizontal sliding fit structure, which can completely compensate for the positional deviation caused by the horizontal adjustment of the moving frame 12, so that the horizontal width adjustment action and the vertical thickness follow-up action are completely decoupled and do not interfere with each other. During the thickness follow-up process, the vertical lifting and lowering action of the nozzle is not affected by the horizontal position. This achieves complete decoupling of the width adjustment degree of freedom and the thickness follow-up degree of freedom, ensuring smooth, accurate and reliable mechanism operation.

[0137] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A back-side protection device for laser welding of automotive variable thickness plates, comprising a machine base (1), a laser welding gun (2), and a movable stage (3) slidably mounted on the machine base (1), wherein the laser welding gun (2) is fixedly disposed above the machine base (1), and the movable stage (3) is used to support the automotive variable thickness plate to be welded, characterized in that, Also includes: A drive assembly is provided on the machine base (1) for driving the moving table (3) carrying the automotive variable thickness plate to move toward the laser welding gun (2); A positioning component located on the mobile platform (3) is used to clamp and fix two variable thickness plates to be spliced ​​and welded according to the width of the automotive variable thickness plate. A protective nozzle (4) is set on the moving platform (3) and located directly below the laser welding gun (2). A floating mechanism is provided between the protective nozzle (4) and the nozzle of the laser welding gun (2). The floating mechanism is used to sense the thickness change of the automotive variable thickness plate during the welding process and adjust the vertical distance between the protective nozzle (4) and the bottom of the automotive variable thickness plate according to the thickness change.

2. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 1, characterized in that, The driving component includes: A first motor (5) is fixedly installed on the machine base (1). The output shaft of the first motor (5) is fixedly connected to a lead screw (6), and one end of the lead screw (6) is rotatably installed on the machine base (1) through a bearing. An extension plate is fixed to the lower end of the moving platform (3), and the extension plate is threadedly installed on the lead screw (6); And guide rails fixedly installed on both sides of the machine base (1), and sliding blocks with their tops fixed to the bottom of the moving platform (3) are slidably installed on the guide rails.

3. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 2, characterized in that, The positioning component includes: A second motor (7) is fixedly installed on one side of the top of the mobile platform (3), and the output shaft of the second motor (7) is fixedly connected to a bidirectional threaded rod (8); A pair of symmetrically threaded clamps (9) are installed at both ends of the surface of the bidirectional threaded rod (8) and a guide rod (10) is slidably installed between the bottoms of the two clamps (9) via a sliding sleeve. The two ends of the guide rod (10) are fixed on the moving table (3). Two brackets (301) are symmetrically fixed to the surface of the moving platform (3). Each clamp (9) is located at the end of the corresponding bracket (301) and is used to clamp and position the end of the variable thickness plate after it is placed on the bracket (301).

4. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 3, characterized in that, The floating mechanism includes: A mounting bracket (11) is detachably mounted on the laser welding gun (2), and the mounting bracket (11) is horizontally arranged on the laser welding gun (2); The movable frame (12) is mounted on the mounting bracket (11), and the bottom of the movable frame (12) has ball bearings. The bottom of the movable frame (12) is supported by the ball bearings rolling on the surface of the movable platform (3). An assembly slot is provided at the lower end of the movable frame (12), and a connecting plate is fixed at the upper end of the assembly slot; A movable rod (13) is vertically and movably installed on the connecting plate. A thickness measuring roller (14) is installed at the bottom of the movable rod (13). The bottom of the thickness measuring roller (14) abuts against the side edge of the bracket (301). A first spring (15) is sleeved on the movable rod (13), and the two ends of the first spring (15) abut against the bottom surface of the connecting plate and the top surface of the thickness measuring roller (14), respectively. A connecting rod (16) extends through one side of the connecting plate, and the top of the connecting rod (16) is fixedly connected to the top of the movable rod (13); The guide sleeve (17) is fixed to the bottom of the connecting rod (16) and the pull rod (18) is slidably passed through the middle of the guide sleeve (17) in the horizontal direction. The lower end of the pull rod (18) is slidably installed on the surface of the moving platform (3) along the moving direction of the moving platform (3). A U-shaped sleeve (19) is fixed to the pull rod (18) and close to one end of the laser welding gun (2). The protective nozzle (4) is installed inside the U-shaped sleeve (19). The air outlet of the protective nozzle (4) faces the bottom of the automotive variable thickness plate. And an adjustment component disposed between the protective nozzle (4) and the U-shaped sleeve (19), the adjustment component being used to adjust the blowing angle of the protective nozzle (4) accordingly when the U-shaped sleeve (19) floats up and down.

5. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 4, characterized in that, The connecting plate has through holes on both sides. The inner wall of the through holes has multiple first grooves equidistantly spaced along the circumference. First balls are rolled in the first grooves. One side of the first ball rolls against the surface of the corresponding movable rod (13) or connecting rod (16).

6. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 4, characterized in that, The floating mechanism also includes: Two T-shaped rods (20) are symmetrically fixed to the bottom of the pull rod (18) and a slider (21) is slidably sleeved on each of the T-shaped rods (20). Two symmetrical grooves (22) are symmetrically opened through the surface of the moving platform (3), and the slider (21) is slidably installed in the corresponding groove (22); And a second spring (23) sleeved on the lower end of the T-shaped rod (20), the two ends of the second spring (23) being fixed between the bottom surface of the slider (21) and the bottom end of the T-shaped rod (20).

7. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 4, characterized in that, The adjustment component includes: Pins are symmetrically fixed on both sides of the middle part of the protective nozzle (4), and the pins are rotatably installed on the inner wall of the U-shaped sleeve (19); Connecting block (24) fixed to the inner wall of the U-shaped sleeve (19); A pressure rod (25) is vertically and movably inserted through the middle of the connecting block (24), and the bottom of the pressure rod (25) abuts against the surface of the moving platform (3); A connecting plate (26) is fixedly installed in the middle of the pressure bar (25); A third spring (27) is sleeved on the pressure rod (25), and the two ends of the third spring (27) abut against the bottom surface of the connecting block (24) and the top surface of the connecting plate (26), respectively. Two pairs of sliding grooves (28) are respectively opened on the inner walls of the two sides of the U-shaped sleeve (19); A sliding block (29) is slidably installed in each of the sliding grooves (28), and a positioning pin is fixed on the sliding block (29); The first hinge rod (30) is hinged at both ends to the top of the connecting plate (26) and the corresponding positioning pin, respectively. A second hinge rod (31) with one end hinged to the positioning pin; A third hinge rod (32) is hinged to the other end of the second hinge rod (31), wherein two of the third hinge rods (32) located on the side near the protective nozzle (4) are fixedly installed on the lower outer wall of the protective nozzle (4); And a guide plate (33) fixedly installed between the two third hinge rods (32) on the side away from the protective nozzle (4). The middle two sides of the guide plate (33) are hinged to the inner wall of the U-shaped sleeve (19). When the U-shaped sleeve (19) is raised and lowered, the connecting plate (26) moves vertically, driving the sliding block (29) at one end of the first hinge rod (30) to slide in the sliding groove (28). Then, through the second hinge rod (31) and the third hinge rod (32), the protective nozzle (4) and the guide plate (33) are driven to deflect relative to each other around their respective hinge axes, so as to change the blowing angle of the protective nozzle (4).

8. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 7, characterized in that, The upper end of the pressure rod (25) is fixed with two limiting rings at intervals along its axial direction. The two limiting rings are used to limit the vertical movement of the pressure rod (25) relative to the connecting block (24).

9. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 8, characterized in that, The protective device further includes a flow regulating component disposed inside the protective nozzle (4), the flow regulating component being used to change the outlet flow rate according to the deflection action of the protective nozzle (4), the flow regulating component including: The piston rod (34) is movable and passes through the lower end of the protective nozzle (4). A stopper disc (35) is fixed to one end of the piston rod (34) inside the protective nozzle (4), and the stopper disc (35) is sealed and fitted to the inner wall of the protective nozzle (4). A conical valve core (36) is fixed to the top of the plug disc (35); A ball fixed to the bottom end of the piston rod (34), the diameter of the ball being larger than the diameter of the piston rod (34); A fourth spring (37) is sleeved on the lower end of the piston rod (34), and the two ends of the fourth spring (37) abut against the bottom surface of the protective nozzle (4) and the surface of the ball, respectively. And a pressure block (38) fixedly installed on the surface of the moving platform (3). The pressure block (38) has an inclined surface that cooperates with the ball on the side near the protective nozzle (4). When welding to the thin area of ​​the automotive variable thickness plate, the U-shaped sleeve (19) drives the protective nozzle (4) to descend, so that the ball squeezes the inclined surface of the pressure block (38), thereby pushing the piston rod (34) and the conical valve core (36) to move upward, so as to reduce the air flow of the air outlet of the protective nozzle (4).

10. The back-side follow-up protection device for laser splicing of automotive variable thickness plates according to claim 4, characterized in that, The floating mechanism also includes: A connecting sleeve is fixed to the top of the movable frame (12), and the connecting sleeve is slidably installed on the surface of the mounting frame (11); Multiple adjustment holes (39) are equally spaced on the surface of the mounting bracket (11) along the vertical direction. U-shaped mounting block (40) fixed to the top of the connecting sleeve; A locking pin (41) that penetrates vertically through the U-shaped mounting block (40) and the connecting sleeve, with the lower end of the locking pin (41) inserted into a corresponding adjustment hole (39); And a fifth spring (42) sleeved on the locking pin (41), the two ends of the fifth spring (42) respectively abutting the top wall of the U-shaped mounting block (40) and the top surface of the connecting sleeve.

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