Battery tray welding apparatus and welding method thereof

Abstract

The application provides a battery bottom support welding device and a welding method thereof, and relates to the technical field of welding.The battery bottom support welding device comprises a gantry assembly, a tooling assembly, a welding head mounting assembly, a stirring welding assembly and a driving assembly.The gantry assembly is provided with a main shaft box.The tooling assembly is arranged below the main shaft box and is used for clamping a workpiece to be welded.The welding head mounting assembly is fixed to the bottom end of the main shaft box through a mounting seat, and the welding head mounting assembly is provided with a cavity.The stirring welding assembly is rotatably arranged at the bottom of the welding head mounting assembly, the lower end of the stirring welding assembly is a stirring head, and the upper end of the stirring welding assembly extends into the cavity.The driving assembly is arranged on the welding head mounting assembly and is used for driving the stirring welding assembly to rotate.The laser welding assembly is at least partially integrated into the welding head mounting assembly and comprises a fiber optic hose used for leading out laser, a light splitting cover and at least one laser welding head, so that the welding points of the weld are pre-fixed before welding.The pre-fixed welding points can withstand the vibration impact in the welding process, the separation and the misalignment of the plates are limited, the opening amount of the weld to the two sides is reduced, and the generation of the flash and the tunnel defects is inhibited.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically, to a battery base welding device and a welding method thereof. Background Technology

[0002] The battery base is the load-bearing component of the battery pack in new energy vehicles. It is usually made of a frame and a base plate welded together, and has high requirements for the strength, sealing and deformation of the welds.

[0003] Friction stir welding, as a solid-state joining technology, has advantages such as small welding deformation, high joint strength, and no spatter or fumes, and is gradually being applied to the manufacturing of battery bases. However, in the actual welding process, when the stirring head shoulder is pressed into the workpiece surface at a preset depth, the high-speed rotating stirring pin and shoulder violently agitate and compress the surrounding metal, causing the ductile metal at the weld to be forcefully squeezed out to both sides. This phenomenon can cause burrs and flaking at the weld edges, and at the same time, insufficient filling of the weld interior due to material loss can easily lead to tunnel-like voids or loose defects, severely reducing the load-bearing capacity and sealing performance of the joint.

[0004] To mitigate these defects, one approach is to pre-fix the relative positions of the workpieces to be welded before the actual welding, thereby reducing weld spread by constraining the separation and misalignment of the plates. Conventional pre-fixing methods include pre-installing locating pins or pre-setting resistance spot welding. However, pre-installing locating pins requires additional clamping procedures and components, making the operation cumbersome; resistance spot welding requires independent spot welding equipment, increasing the number of workstations and costs. Furthermore, considering the low weld strength of spot welding, the welding vibration during continuous friction stir welding will continuously impact the weld joint, posing a risk of loosening under high-frequency vibration, thus reducing the effectiveness of pre-fixing.

[0005] In addition, the low temperature of the stirring head during the initial stage of welding and the insufficient plasticization of the material further exacerbated the tendency of the weld to spread to both sides, affecting the welding quality. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a battery base welding device and welding method, which solves the problems of weld formation defects caused by the extrusion of plastic metal during friction stir welding, as well as unreliable workpiece fixation and inconvenient preheating of the stirring head.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a battery base welding device, comprising: a gantry assembly on which a spindle box is mounted; a tooling assembly disposed below the spindle box for clamping the workpiece to be welded; a welding head mounting assembly fixed to the bottom of the spindle box by a mounting base, the welding head mounting assembly having a cavity; a stir welding assembly rotatably mounted on the bottom of the welding head mounting assembly, the lower end of which is a stir head and the upper end extending into the cavity; a drive assembly mounted on the welding head mounting assembly for driving the stir welding assembly to rotate; and a laser welding assembly, at least partially integrated within the welding head mounting assembly, including a fiber optic tube for extracting laser light, a beam splitter, and at least one laser welding head, the laser welding head being mounted on the bottom of the welding head mounting assembly, the laser welding head being tilted, and the focal point formed by the convergence of the emitted laser beam being located directly below the stir head, so as to pre-fix the weld joint before welding.

[0008] According to one embodiment of the present invention, the spindle box is capable of moving along the X, Y, and Z directions under the drive of the gantry assembly; the tooling assembly includes a tooling base and a plurality of clamping cylinders.

[0009] According to one embodiment of the present invention, the welding head mounting assembly includes a cover and a housing, the cavity being disposed within the housing; a plurality of light guiding channels are provided along the Z direction on the housing; the top of the beam splitter is provided with a light inlet, and the periphery is provided with light outlets corresponding to the number and position of the light guiding channels; the laser welding head is mounted at the outlet end of the light guiding channels.

[0010] According to one embodiment of the present invention, the laser welding assembly further includes: a collimating lens installed at the light inlet of the beam splitter; a beam splitter installed inside the beam splitter and facing the light inlet, for splitting the laser into multiple beams and directing them toward each light outlet; a right-angle reflector installed at each of the light outlets, for reflecting the laser vertically into the light guide channel; a first focusing lens installed in the middle of each of the light guide channels; and a laser reflector and a second focusing lens installed sequentially from top to bottom inside the laser welding head; wherein, the laser entering the laser welding head is reflected by the laser reflector to form a beam parallel to the length direction of the laser welding head, and is focused by the second focusing lens onto the area directly below the stirring head.

[0011] According to one embodiment of the present invention, the laser welding head is inclined, and its extension line in the length direction intersects the axis of the stir welding assembly.

[0012] According to one embodiment of the present invention, the drive assembly includes a motor, a power shaft connected to the output end of the motor, a first bevel gear mounted on the power shaft, and a second bevel gear meshing with the first bevel gear in the cavity; the second bevel gear is connected to the upper end of the stir welding assembly; the light guide channel is spatially offset from the cavity.

[0013] According to one embodiment of the present invention, the assembly further includes a transposition disk and a joining assembly; the transposition disk is rotatably mounted on the bottom of the housing, and at least two types of laser welding heads are provided on the transposition disk; the beam emitted by one laser welding head is focused directly below the stirring head, and the beam emitted by the other laser welding head is focused on the stirring head; the joining assembly is disposed in the cavity and includes an electromagnet, a clutch disk, and a magnet, the clutch disk being fixed to the upper end of the stirring welding assembly so as to rotate synchronously with the stirring welding assembly under the drive of the drive assembly; the upper end face of the transposition disk is provided with a rotating block, the top of the rotating block is provided with an inclined groove, and the magnet is slidably disposed in the inclined groove; after the electromagnet is energized, it attracts the magnet to move upward along the inclined groove and abut against the inner wall of the flange, forming a frictional fixed connection, so that the clutch disk drives the transposition disk to rotate, realizing the switching connection between the light guide channel and the first welding head or the second welding head; after the electromagnet is de-energized, the magnet falls back along the inclined groove under the action of gravity, so as to release the frictional fixed connection.

[0014] According to one embodiment of the present invention, the housing is provided with an arc-shaped groove adapted to the rotating block, the inner wall of the arc-shaped groove is provided with a position protrusion, and the side wall of the rotating block is provided with a positioning recess that cooperates with the position protrusion, so as to achieve positioning and locking after switching is completed.

[0015] The present invention also provides a welding method for a battery base, comprising the following steps: S1, clamping and pressing the frame and base plate of the workpiece to be welded onto the tooling assembly; S2, the spindle box drives the welding head mounting assembly to move along the weld path, while simultaneously turning on the laser welding assembly to form a pre-fixed weld point at the weld, pre-fixing the frame and the base plate; S3, turning off the laser welding assembly, starting the drive assembly to rotate the stir welding assembly, pressing down the spindle box to make the stirring head reach the preset welding depth, and completing the stir friction welding along the weld trajectory.

[0016] According to one embodiment of the present invention, before step S2, step S20 is further included: the second welding head on the transposition disk is switched to communicate with the light guide channel by the bonding assembly, and the laser is turned on to focus its focus on the side wall of the stirring head to preheat the stirring head; after the preheating is completed, the transposition disk is switched back to the first welding head by the bonding assembly again, and step S2 is executed again.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. In this invention, a pre-fixed weld point is pre-formed at the weld seam before friction stir welding using an integrated laser welding assembly, thereby pre-fixing the frame and the base plate. The pre-fixed weld point can withstand the vibration and impact during the welding process, restrict the separation and misalignment of the plates, reduce the amount of weld seam opening to both sides, suppress the generation of flash and tunnel defects, and improve the weld quality.

[0018] 2. In this invention, the same laser welding assembly can be used to pre-fix the weld points and heat the lower edge of the shoulder of the stirring head during the preheating stage by using the switchable laser welding head. The rotation of the stirring head forms a uniform annular heating band, and the heat is transferred to the entire stirring head through heat conduction, thereby preheating the stirring head. This allows the material in the initial welding section to enter the plastic state more quickly, reducing the deformation resistance and helping to improve the weld formation.

[0019] 3. In this invention, the welding head mounting assembly integrates two sets of laser light paths through a beam splitter, a light guide channel, and a bonding assembly, thus eliminating the need for an additional heating device, ensuring the compactness of the structure, and improving the process adaptability and production efficiency of the equipment. Attached Figure Description

[0020] Figure 1 This is an overall structural diagram of a battery base welding device according to the present invention; Figure 2 This is a diagram showing the connection structure between the welding head mounting assembly and the mounting base in this invention; Figure 3 This is an internal cross-sectional view of the welding head mounting assembly in this invention; Figure 4 This is a schematic diagram of the optical path principle of the laser welding assembly in this invention; Figure 5 This is a structural diagram of the tooling assembly clamping the workpiece to be welded in this invention; Figure 6 for Figure 5 Top view; Figure 7 This is a distribution diagram of pre-fixed weld points at the weld seam of the workpiece to be welded in this invention; Figure 8 This is a structural diagram of the welding head mounting assembly in Embodiment 2 of the present invention; Figure 9 This is an internal cross-sectional view of the welding head mounting assembly in Embodiment 2 of the present invention; Figure 10 This is a connection structure diagram of the joining component and the transposition disk in Embodiment 2 of the present invention; Figure 11 This is a schematic diagram showing the position of focus A1 of the first welding head in Embodiment 2 of the present invention; Figure 12 This is a schematic diagram showing the position of focus A2 of the second welding head in Embodiment 2 of the present invention; Figure 13 for Figure 10 Cross-sectional structural diagram; Figure 14 for Figure 13 Enlarged structural diagram at point B; Figure 15 This is a diagram showing the engagement state of the rotating block and the clutch disc in Embodiment 2 of the present invention; Figure 16 This is a structural diagram of the light guide channel and cavity in the housing of the present invention; Figure 17 This is a structural diagram of the transposition disk in Embodiment 3 of the present invention; Figure 18 This is a cross-sectional view of the transposition disk in Embodiment 3 of the present invention.

[0021] Figure label: 1. Gantry frame assembly; 11. Spindle box; 12. Mounting base; 2. Tooling components; 21. Tooling base; 22. Clamping cylinder; 3. Welding head mounting assembly; 31. Cover; 32. Box; 321. Light guide channel; 322. Arc groove; 3221. Position protrusion; 4. Drive assembly; 41. Motor; 411. Drive shaft; 42. First bevel gear; 43. Second bevel gear; 44. Engagement assembly; 441. Electromagnet; 442. Clutch disc; 4421. Flanged edge; 443. Magnet; 5. Laser welding assembly; 51. Fiber optic flexible tube; 52. Beam splitter; 53. Laser welding head; 531. First welding head; 532. Second welding head; 54. Transposition disk; 541. Rotating block; 542. Cooling water channel; 543. Water inlet pipe; 544. Water outlet pipe; 501. Collimating lens; 502. Beam splitter; 503. Right-angle mirror; 504. First focusing lens; 505. Laser mirror; 506. Second focusing lens; 6. Stir welding assembly; 7. Workpiece to be welded; 701. Frame; 702. Base plate. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1, see Figures 1 to 7 This embodiment provides a battery base welding device, including a gantry assembly 1 and a tooling assembly 2. A spindle box 11 is mounted on the gantry assembly 1, and the spindle box 11 can move along the X, Y, and Z directions under the drive of the gantry. (See reference...) Figure 5 and Figure 6The tooling assembly 2 includes a tooling base 21 and multiple clamping cylinders 22. The tooling base 21 supports the workpiece 7 to be welded, and the clamping cylinders 22 firmly clamp the workpiece 7. The tooling assembly 2 is located below the spindle box 11, and the bottom end of the spindle box 11 is fixed with a welding head mounting assembly 3 via a mounting base 12. The welding head mounting assembly 3 integrates a laser welding assembly 5 and a stir welding assembly 6.

[0024] This embodiment employs friction stir welding. During the welding process, once the stirring head reaches the preset depth, the stirring pin and shoulder violently agitate and compress the surrounding metal. This causes the ductile metal at the weld joint to be pushed outwards, forming flash on both sides of the weld. Simultaneously, the weld center may not be fully filled due to material extrusion, resulting in tunnel-type void defects. To eliminate this effect, it is necessary to control the weld gap and fix the relative position of the workpieces to be welded before welding.

[0025] See Figure 2 and Figure 3 The welding head mounting assembly 3 includes a cover 31 and a housing 32. The cover 31 is fixedly mounted on the upper end of the housing 32, and the housing 32 is entirely fixed on the mounting base 12. The drive assembly 4 includes a motor 41, a power shaft 411, a first bevel gear 42, and a second bevel gear 43. The motor 41 is fixed to the mounting base 12 via a bracket plate, and its output end is connected to the power shaft 411. The first bevel gear 42 is mounted on the power shaft 411. The housing 32 has an internal cavity that accommodates the first bevel gear 42 and the second bevel gear 43. The second bevel gear 43 is connected to the upper end of the stir welding assembly 6, which is rotatably mounted on the bottom of the housing 32 via bearings. The lower end of the stir welding assembly is the stirring head. The power from the motor 41 is transmitted to the stir welding assembly 6 via the power shaft 411, the first bevel gear 42, and the second bevel gear 43, driving the stirring pin at its bottom to rotate and perform friction welding.

[0026] It should be noted that in this scheme, the drive component uses a spiral bevel gear pair instead of the traditional direct drive mode. After carburizing, quenching, and grinding, the allowable tooth surface linear velocity of the spiral bevel gear can reach over 40 m / s, achieving a speed requirement of 1000 to 2000 rpm under a conventional pitch circle diameter. The transmission ratio of the bevel gear pair in this scheme can be designed as a 1:1 constant speed transmission, in which case the rated speed of the motor is directly transmitted to the stir welding component without the need for speed reduction; alternatively, the transmission ratio can be adjusted according to different motor speeds and welding process requirements, ensuring that the linear velocity of the small bevel gear is always far below its allowable limit, thereby guaranteeing long-term stable operation in a non-direct drive layout. Next, the stir welding component 6 can be configured as a split structure, for example, it can be composed of a bushing and a stirring head that are detachably connected. The connection structure and method of the bushing and the stirring head are existing technologies and will not be described in detail here.

[0027] See Figure 3 , Figure 4 and Figure 16 The laser welding assembly 5 includes a fiber optic hose 51, a beam splitter 52, and a laser welding head 53. The fiber optic hose 51 is installed inside the spindle housing 11 to guide the laser generated by an external laser. The beam splitter 52 has an inlet port on its top and two or four outlet ports around its perimeter. A light guide channel 321, matching the number of outlet ports, is formed along the Z-direction of the housing 32, with each outlet port corresponding to its top end. The light guide channels 321 are spatially offset from the cavities within the housing 32 to avoid interference between the optical path and the transmission components. Specifically, a collimating lens 501 is installed at the outlet end of the fiber optic hose 51, a beam splitter 502 is installed inside the beam splitter 52 directly opposite the inlet port, and right-angle mirrors 503 are installed at each outlet. A first focusing lens 504 is installed in the middle of each light guide channel 321, and a laser welding head 53 is installed at the outlet end. The laser welding head 53 is tilted, and its interior contains, from top to bottom, a laser reflector 505 and a second focusing mirror 506. The extension of the laser welding head 53 along its length intersects the axis of the stir welding assembly 6; the intersection point is the focal point A1, which is located directly below the stirring pin. Figure 11 As shown.

[0028] The laser transmission path is as follows: the laser beam is drawn out from the fiber optic tube 51, collimated by the collimating lens 501, and then directed to the beam splitter 502. When two output ports are used, the beam splitter 502 has a triangular pyramid structure; when four output ports are used, the beam splitter 502 has a square pyramid structure, with its pyramidal surface always facing the output ports, uniformly splitting the laser beam into multiple beams corresponding to the number of output ports. Each beam is reflected by the right-angle reflector 503 and then perpendicularly enters the light guide channel 321. It is then converged by the first focusing lens 504 and transmitted to the laser welding head 53. After being reflected by the laser reflector 505, it becomes a beam parallel to the length direction of the laser welding head 53, and finally focused by the second focusing lens 506 at the focal point A1, generating extremely high energy density, which can form a weld point on the workpiece to be welded.

[0029] Before operation, tooling assembly 2 clamps and positions the frame 701 and base plate 702 of the workpiece 7 to be welded. The spindle box 11 drives the welding head mounting assembly 3 to move along the weld seam trajectory, while the laser welding assembly 5 operates, pre-processing a series of weld points on the weld seam to fix the relative position of the frame 701 and the base plate 702. Figure 7 As shown. After pre-fixing, the laser welding assembly 5 is turned off, the motor 41 is started, the stir welding assembly 6 rotates, and the spindle box 11 descends to allow the stirring needle to reach the preset depth and complete the friction stir welding along the weld. Because the weld point restricts the relative sliding and separation between the workpieces in advance, the phenomenon of the weld opening to both sides during the welding process is effectively suppressed, the plastic metal flows evenly, the weld is densely formed, and there are no flash or tunnel defects.

[0030] Example 2: In friction stir welding, in order to suppress the weld from spreading to both sides, forming flash and tunnel defects due to low stirring head temperature and insufficient material plasticization in the initial stage of welding, one approach is to use laser to preheat the stirring head to increase its initial temperature; another approach is to pre-form laser welding points on the workpiece to be welded before welding to fix the relative position of the workpiece and limit its separation and misalignment during the welding process.

[0031] However, in practical applications, it has been found that using any one of the above solutions alone still presents the following technical problems: If only the stirring head is laser preheated, it can reach the ideal plasticizing temperature. However, when the stirring head is raised and pressed down to contact the workpiece after preheating, the workpiece material in the initial contact area is still cold before the heat from the stirring head is transferred. Furthermore, preheating itself cannot restrain the separation tendency of the workpiece sheet under welding pressure. There is still a brief window of insufficient low-temperature plasticizing in the initial section of the weld, and the risk of inadequate expansion and filling cannot be completely eliminated.

[0032] If only laser pre-fixation of the weld joint is used, although it can constrain the position of the workpiece, the temperature of the stirring head itself is low at the beginning of welding, and it needs to rely on the friction of the workpiece to gradually heat up. During this process, the squeezing effect of the low-temperature stirring head on the ductile metal is more intense, and the thermal shock and mechanical vibration of the pre-fixed weld joint are also more severe, which may lead to premature failure of the weld joint and a reduction in the pre-fixation effect.

[0033] To solve the above problems, see Figures 8 to 15 This embodiment adds a joining assembly 44 and a transposition disk 54. The transposition disk 54 is rotatably mounted on the bottom of the housing 32, and integrates two laser welding heads with different functions, namely the first welding head 531 and the second welding head 532, on the transposition disk 54. The first welding head 531 has the same structure as the laser welding head 53 in Embodiment 1, and its internal laser reflector 505 and second focusing mirror 506 converge the laser beam to a focal point A1, which is located directly below the stirring needle for pre-fixing of the weld point. Figure 12 As shown, the second welding head 532 has a slightly adjusted tilt angle based on the first welding head 531, so that the beam emitted from its interior is focused at the focal point A2 on the circumferential sidewall at the bottom of the stir welding assembly 6, to heat the stirring head or the shoulder.

[0034] Specifically, during the preheating stage, the spindle box 11 raises the stirring head to maintain a very small gap with the workpiece surface. The motor 41 is started to rotate the stirring head. After the laser is turned on, the focused beam emitted from the second welding head 532 sweeps across the edge of the shoulder end face at an oblique angle. Due to the high-speed rotation of the stirring head, the laser energy forms a continuous, annular, uniform heating band at the lower end face edge of the shoulder or the root of the stirring needle. The heat is rapidly transferred from the shoulder to the entire stirring needle through heat conduction, thereby indirectly and efficiently completing the preheating of the stirring head.

[0035] The engagement assembly 44 is used to achieve a fixed-angle rotation of the transposition disk 54, so as to switch the exit end of the light guide channel 321 between the corresponding first welding head 531 or the second welding head 532. The engagement assembly 44 includes an electromagnet 441, a clutch disk 442, and a magnet 443. The electromagnet 441 is fixed to the inner side wall of the cavity of the housing 32, and the clutch disk 442 is fixed to the upper end of the stir welding assembly 6 and located inside the cavity. The clutch disk 442 has a vertical flange 4421. The upper end face of the transposition disk 54 is provided with two rotating blocks 541. The top of the rotating block 541 has an inclined groove, and the magnet 443 is slidably placed in the inclined groove. When the electromagnet 441 is energized, it pulls the opposing magnet 443 upward along the inclined surface of the inclined groove, so that the magnet 443 abuts against the inner wall of the flange 4421 of the clutch disk 442, generating a frictional connection that can transmit torque. At this time, the power of motor 41 is transmitted to the stir welding assembly 6 and clutch disc 442 via meshing gears. The friction between the magnet and the flange drives the shifting disc 54 to rotate, causing either the first welding head 531 or the second welding head 532 to switch to the area below the light guide channel 321. After the switching is completed, electromagnet 441 is de-energized, magnet 443 falls back to the bottom of the inclined groove under the action of gravity, clutch disc disengages from rotating block, and shifting disc 54 stops rotating.

[0036] To ensure positioning accuracy after switching, please refer to... Figure 15 and Figure 16 The housing 32 has an arc-shaped groove 322 that matches the rotating block 541. The inner wall of the arc-shaped groove 322 has a positioning protrusion 3221, and the side wall of the rotating block 541 has a corresponding positioning recess. When the first welding head 531 or the second welding head 532 is rotated to align with the light guide channel 321, the positioning recess and the positioning protrusion 3221 automatically engage to ensure that the light path can be aligned.

[0037] During welding, the stirring head can be preheated first. The electromagnet 441 is then activated, pulling the magnet 443 from the inclined groove of the rotating block 541 on the shifting disk 54 upwards. The magnet 443 abuts against the inner wall of the flange 4421 of the clutch disk 442, and the two form a fixed connection through friction. At this time, the power of the motor 41 is transmitted to the shifting disk 54 through the first bevel gear 42, the second bevel gear 43, and the clutch disk 442, driving the shifting disk 54 to rotate until the light guide channel 321 is aligned with the second welding head 532. The positioning recess on the rotating block 541 engages and locks with the position protrusion 3221 in the arc groove 322 of the housing 32. Then, the electromagnet 441 is de-energized, and the magnet 443 falls back under gravity, releasing the frictional connection and completing the positioning of the second welding head 532. The spindle box 11 raises the stirring head to form a gap with the workpiece surface, and the motor 41 is started to drive the stirring head to rotate. When the laser is turned on, the laser beam is distributed by the beam splitter 52 and enters the second welding head 532 through the light guide channel 321. The laser beam is focused by the laser reflector 505 and the second focusing mirror 506 inside the head and is focused at the focal point A2 on the lower end face edge of the stirring head shoulder. As the stirring head continues to rotate, the laser energy forms an annular heating band on the lower end face edge of the shoulder. The heat is transferred from the shoulder to the stirring needle through heat conduction, raising the overall temperature of the stirring head to the set value required for the plastic flow of the material, thereby reducing the deformation resistance of the material in the initial stage of welding.

[0038] After preheating, electromagnet 441 is turned on again, and the shifting disk 54 is rotated using the same friction-fixed connection and clutch switching method, so that the first welding head 531 is aligned and locked with the light guide channel 321. The laser is turned on, and the laser beam is focused by the first welding head 531 at the focal point A1 directly below the weld, forming a series of laser welding points at a preset interval on the weld between the frame 701 and the base plate 702, pre-fixing the relative positions of the two to limit the separation and misalignment of the plates during the welding process.

[0039] After pre-fixing, the laser is turned off, and the stir welding assembly 6 is started. The spindle box 11 presses down the stirring head to the preset welding depth and completes the friction stir welding along the weld seam trajectory. Thanks to the preheating of the stirring head, which allows the material to plasticize more quickly, and the constraint effect of the pre-fixed weld point on both sides of the weld seam, the phenomenon of plastic metal extrusion at the weld seam is suppressed, flash and tunnel-type hole defects are reduced, and the weld seam is formed densely and has a smooth surface. Throughout the process, the stirring head preheating and weld point pre-fixing are both achieved by the same set of laser welding assembly 5 and the welding head is switched through the switching plate 54. No additional heating device is required, the structure is highly integrated, the control is flexible, the extrusion phenomenon in the initial stage of the weld seam is reduced, and the welding quality is improved.

[0040] In Example 3, in the technical solution of Example 2, the heat generated by the friction between the stirring head and the workpiece during welding operations in the stir welding assembly will raise the temperature of the surrounding area. The laser welding head is mounted on the transposition plate and is relatively close to the stir welding assembly, posing a risk that the temperature of the laser welding head may exceed its allowable operating range due to heat conduction and heat radiation.

[0041] To address the aforementioned issues, this embodiment further improves the structure of the transposition disk based on Embodiment 2.

[0042] See Figure 17 and Figure 18 The transposition disk 54 has a cooling water channel 542 inside. This cooling water channel 542 is located inside the disk body of the transposition disk 54, and its path extends around the areas where each laser welding head (i.e., the first welding head 531 and the second welding head 532) is located. One end of the cooling water channel 542 is connected to an inlet pipe 543, and the other end is connected to an outlet pipe 544. Cooling medium (such as water or coolant) enters the cooling water channel 542 through the inlet pipe 543, flows inside the transposition disk 54 and carries away heat, and is then discharged through the outlet pipe 544, thereby cooling the various laser welding heads installed on the transposition disk 54.

[0043] The cooling water channel 542 passes through the central region of the transposition plate 54, allowing the central part of the transposition plate 54 to also be cooled by the cooling medium. In this way, the heat conducted from the housing to the transposition plate 54 is absorbed and carried away by the flowing medium in the cooling water channel 542 before reaching the laser welding head installation position, reducing the rate at which heat is continuously transferred to the laser welding head.

[0044] With the above configuration, when the stir welding assembly is in welding condition and the ambient temperature is high, the cooling water channel 542 inside the transposition disk 54 can provide continuous cooling for the first welding head 531 and the second welding head 532, keeping their own temperature within a range suitable for long-term operation. At the same time, the cooling in the middle of the transposition disk 54 also helps to reduce the thermal impact on other components mounted on it due to the increased disk temperature.

[0045] It should be noted that the inlet pipe 543 and the outlet pipe 544 can be made of flexible pipes to accommodate the rotational displacement of the switching plate 54 when switching welding heads; a rotary joint can also be installed at the rotating shaft of the switching plate 54 to achieve continuous supply of cooling medium.

[0046] The remaining structure and operation of this embodiment are the same as those of Embodiment 2, and will not be repeated here.

[0047] Example 4: Based on Example 1 or Example 2 above, this example provides a welding method for a battery base. The workpiece in this example is a battery base, including a frame 701 and a base plate 702. The specific steps are as follows: S1. Workpiece clamping and positioning.

[0048] The frame 701 and base plate 702 of the workpiece 7 to be welded are assembled and placed on the fixture seat 21 of the fixture assembly 2. The positioning reference surface on the fixture seat 21 is used to ensure the assembly gap and relative position of the two, ensuring uniform weld. Multiple clamping cylinders 22 are activated, and the pressure head of the clamping cylinder 22 acts on the upper surface of the frame 701, pressing the frame 701 and base plate 702 firmly onto the fixture seat 21, ensuring that the workpiece 7 to be welded does not tilt or hang.

[0049] S2. Pre-fixing of weld seams.

[0050] Start the gantry assembly 1, controlling the spindle box 11 to move the welding head mounting assembly 3 above the weld start point. Turn on the laser welding assembly 5; the laser is introduced through the light inlet of the beam splitter 52, split by the beam splitter 502, redirected by the right-angle reflector 503, and then transmitted vertically along the light guide channel 321. It is focused by the first focusing mirror 504, reflected by the laser reflector 505, and then focused by the second focusing mirror 506 onto focal point A1 directly below the stirring head. The spindle box 11 moves along the weld track according to the preset welding path and travel speed, setting weld points one by one at predetermined intervals at the weld between the frame 701 and the base plate 702. Figure 7 As shown, the relative positions of the frame 701 and the base plate 702 are fixed to form a pre-fixed structure.

[0051] In step S2, if the device of Embodiment 2 is used, the first welding head 531 needs to be switched to the lower part of the light guide channel 321 in advance by the joining component 44, and locked by the position protrusion 3221 in the arc groove 322 and the positioning recess on the side wall of the rotating block 541 to ensure that the light path is aligned.

[0052] S20. Laser preheating of the stirring head. This step uses a welding device for a battery base according to Example 2, and is performed before step S2.

[0053] Specifically: When electromagnet 441 is turned on, it pulls the magnet 443 upward from the inclined groove of rotating block 541 on the transposition disk 54. The magnet 443 abuts against the inner wall of the flange 4421 of clutch disk 442, and the two form a fixed connection through friction. At this time, motor 41 is started, and power is transmitted to stir welding assembly 6 and clutch disk 442 through power shaft 411, first bevel gear 42, and second bevel gear 43. The clutch disk 442 drives the transposition disk 54 to rotate as a whole until the exit end of light guide channel 321 is aligned with the second welding head 532. The positioning recess on rotating block 541 engages and locks with the corresponding position protrusion 3221 in arc groove 322. Then, electromagnet 441 is de-energized, and magnet 443 falls back along the inclined groove under the action of gravity. The frictional fixed connection is released, and the second welding head 532 is positioned.

[0054] Further, the spindle box 11 raises the stirring head, creating a gap between the stirring head and the workpiece surface, and the motor 41 is started to drive the stirring head to rotate. The laser is activated, and the laser beam is focused by the laser reflector 505 and the second focusing lens 506 inside the second welding head 532 onto the focal point A2 at the lower edge of the stirring head shoulder. As the stirring head continues to rotate, the laser energy forms a ring-shaped heating band at the lower edge of the shoulder. Heat is transferred from the shoulder to the stirring needle through thermal conduction, raising the overall temperature of the stirring head to the set value required for the plastic flow of the material, thereby reducing material deformation resistance and extrusion caused by excessively low stirring head temperature during the initial welding stage. After preheating, the switching disk 54 is switched to position with the first welding head 531 in the same manner, and step S2 is executed.

[0055] S3. Perform friction stir welding.

[0056] The laser welding assembly 5 is turned off, and the motor 41 is started. Power is transmitted through the meshing of the first bevel gear 42 and the second bevel gear 43, driving the stir welding assembly 6 to rotate. The spindle box 11 moves downward along the Z-axis, causing the shoulder of the stirring head to press into the workpiece surface at the set welding depth. The stirring needle enters the weld seam, and the spindle box 11 moves along the weld seam trajectory at the preset welding speed, completing the stir friction welding of the entire weld seam.

[0057] During the welding process, the pre-fixed weld points set in step S2 constrain the separation and misalignment between the frame 701 and the base plate 702, thus suppressing the outward extrusion of plastic metal on both sides of the weld and reducing flash and tunnel-type hole defects.

[0058] If step S20 is performed, the increased initial temperature of the stirring head allows the material in the initial welding section to enter a plastic state more quickly, further reducing the initial weld defect tendency. The final weld is dense, with a smooth surface, and the joint strength and sealing meet the requirements for use with the battery base.

[0059] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A battery base welding device, characterized in that, include: Gantry assembly (1), on which a spindle box (11) is mounted; Tooling assembly (2) is located below the spindle box (11) and is used to clamp the workpiece (7) to be welded. The welding head mounting assembly (3) is fixed to the bottom end of the spindle box (11) by the mounting base (12), and the welding head mounting assembly (3) has a cavity inside; The stir welding assembly (6) is rotatably mounted on the bottom of the welding head mounting assembly (3), with the lower end being the stirring head and the upper end extending into the cavity; The drive assembly (4) is mounted on the welding head mounting assembly (3) and is used to drive the stir welding assembly (6) to rotate; The laser welding assembly (5) is at least partially integrated into the welding head mounting assembly (3), including a fiber optic hose (51) for drawing out the laser, a beam splitter (52) and at least one laser welding head (53). The laser welding head (53) is mounted on the bottom of the welding head mounting assembly (3). The laser welding head (53) is tilted and the focal point formed by the laser beam emitted by it is located directly below the stirring head, so as to pre-fix the weld joint before welding. The welding head mounting assembly (3) includes a cover (31) and a box (32), and the cavity is located inside the box (32); the box (32) has multiple light guide channels (321) opened along the Z direction; the top of the beam splitter (52) is provided with a light inlet, and the surrounding area is provided with light outlets corresponding to the number and position of the light guide channels (321); the laser welding head (53) is installed at the outlet end of the light guide channel (321); It also includes a transposition plate (54) and a coupling assembly (44). The transposition disk (54) is rotatably mounted on the bottom of the housing (32). The transposition disk (54) is provided with at least two kinds of laser welding heads (53). The beam emitted by one laser welding head (53) is focused directly below the stirring head, and the beam emitted by the other is focused on the stirring head. The joining assembly (44) is located in the cavity and includes an electromagnet (441), a clutch disk (442) and a magnet (443). The clutch disk (442) is fixed to the upper end of the stirring welding assembly (6) so as to rotate synchronously with the stirring welding assembly (6) under the drive of the driving assembly (4). The upper end face of the transposition disk (54) is provided with a rotating block (541). The top of the rotating block (541) is provided with an inclined groove, and the magnet (443) is slidably located in the inclined groove. When the electromagnet (441) is energized, it attracts the magnet (443) to move upward along the inclined groove and abut against the inner wall of the flange (4421) to form a frictional fixed connection, so that the clutch disc (442) drives the switching disc (54) to rotate, thereby realizing the switching connection between the light guide channel (321) and the first welding head (531) or the second welding head (532); when the electromagnet (441) is de-energized, the magnet (443) falls back along the inclined groove under the action of gravity to release the frictional fixed connection.

2. The battery base welding equipment according to claim 1, characterized in that, The spindle box (11) can move along the X, Y, and Z directions under the drive of the gantry assembly (1); the tooling assembly (2) includes a tooling seat (21) and multiple clamping cylinders (22).

3. The battery base welding equipment according to claim 1, characterized in that, The laser welding assembly (5) also includes: A collimating lens (501) is installed at the light inlet of the beam splitter (52); A beam splitter (502) is installed inside the beam splitter (52) and faces the light inlet, and is used to split the laser into multiple beams and direct them to the light outlets. A right-angle reflector (503) is installed at each of the light outlets to reflect the laser into the light guide channel (321) vertically. A first focusing lens (504) is installed in the middle of each of the light guide channels (321); The laser reflector (505) and the second focusing lens (506) are installed in the laser welding head (53) from top to bottom; The laser entering the laser welding head (53) is reflected by the laser reflector (505) to form a beam parallel to the length direction of the laser welding head (53), and is focused by the second focusing mirror (506) directly below the stirring head.

4. The battery base welding equipment according to claim 3, characterized in that, The laser welding head (53) is inclined, and its extension line in the length direction intersects the axis of the stir welding assembly (6).

5. The battery base welding equipment according to claim 1, characterized in that, The drive assembly (4) includes a motor (41), a power shaft (411) connected to the output end of the motor (41), a first bevel gear (42) mounted on the power shaft (411), and a second bevel gear (43) meshing with the first bevel gear (42) in the cavity; the second bevel gear (43) is connected to the upper end of the stir welding assembly (6); the light guide channel (321) is spatially offset from the cavity.

6. The battery base welding equipment according to claim 1, characterized in that, The housing (32) has an arc-shaped groove (322) adapted to the rotating block (541). The inner wall of the arc-shaped groove (322) has a position protrusion (3221). The side wall of the rotating block (541) has a positioning recess that cooperates with the position protrusion (3221) so as to achieve positioning and locking after switching.

7. A method for welding a battery base, using a battery base welding apparatus as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1, clamp and press the frame (701) and base plate (702) of the workpiece (7) to be welded onto the tooling assembly (2); S2, the spindle box (11) drives the welding head mounting assembly (3) to move along the weld path, and at the same time, the laser welding assembly (5) is turned on to form a pre-fixed welding point at the weld, and the frame (701) and the base plate (702) are pre-fixed. S3, turn off the laser welding assembly (5), start the drive assembly (4) to make the stir welding assembly (6) rotate, the spindle box (11) presses down to make the stirring head reach the preset welding depth, and complete the stir friction welding along the weld track.

8. The welding method for a battery base according to claim 7, characterized in that, Before step S2, step S20 is also included: the second welding head (532) on the transposition disk (54) is switched to be connected with the light guide channel (321) by the bonding component (44), and the laser is turned on to focus its focus on the side wall of the stirring head to preheat the stirring head; after the preheating is completed, the transposition disk (54) is switched back to the first welding head (531) by the bonding component (44) again, and then step S2 is executed.

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