A handheld laser welding system and method that avoids wire fill welding end collapse

Abstract

The application discloses a handheld laser welding system and method for avoiding end collapse of wire filling welding, and the system comprises a laser driving module for exciting welding laser, a motor swing controller for controlling swing of the welding laser, a wire feeding controller for controlling wire feeding and wire drawing, an optical regulation module for controlling welding laser focus variation, and a welding machine controller for controlling welding laser power. The application eliminates end collapse of traditional welding through power slow reduction, swing narrowing and step wire feeding cooperation. Through low power, minimum light spot and accurate wire drawing combination, the application eliminates wire sticking defects, and greatly reduces end defect rate.

Description

Technical Field

[0001] This invention belongs to the field of laser welding technology, and particularly relates to a handheld laser welding system and method for avoiding the collapse of the filler wire welding end. Background Technology

[0002] Laser filler wire welding refers to welding where wire is fed in simultaneously. The laser forms a molten pool in the base material, while the molten wire fills the pool. Filler wire welding effectively compensates for evaporating metal and spattering metal during welding, resulting in a full and smooth weld. Handheld laser filler wire welding involves a person holding the welding head. During handheld filler wire welding, the hand remains relaxed, and the pushing force of the filler wire propels the hand in the welding direction to achieve a stable welding speed.

[0003] Laser welding requires a uniform surface and appropriate weld elevation, meaning the weld is slightly higher than the material plane. However, in practical welding applications, weld end collapse is very common. Laser weld end collapse, also known as arc-end pit or termination hole, is a common laser welding defect. It mainly causes the following problems: 1. Stress tends to concentrate in the collapsed area, resulting in insufficient weld strength; 2. The fatigue characteristics of the weld deteriorate, resulting in a significant reduction in weld life; 3. Induces cracks and other defects; 4. Insufficient weld sealing; 5. It affects the appearance, causing unevenness in the weld seams on the surface.

[0004] When performing handheld laser filler wire welding, wire sticking is a common problem. This occurs when welding stops, and the wire adheres to the weld seam as it solidifies, affecting subsequent welding operations. The main reason for wire sticking is that after welding, the laser energy input stops, and the molten pool rapidly cools and solidifies. If the filler wire is still in contact with the molten pool at this time, it will stick to the weld. To solve this problem, the filler wire is usually stopped synchronously with the laser, and a wire-pulling action is performed—retracting the filler wire a certain distance to ensure it is detached from the molten pool before it solidifies. However, this wire-pulling action can prevent further filler work at the end of the weld, which is one of the main causes of weld collapse at the end.

[0005] In addition, laser welding mainly uses laser energy to create a "keyhole" to achieve welding speed, as shown in the diagram below. Laser energy causes the metal to vaporize rapidly, creating vapor pressure that forms a relatively deep keyhole, allowing the laser to penetrate deeper into the metal and increase the weld penetration.

[0006] During laser welding, a molten pool forms around the keyhole. Under the influence of gravity and the pressure of the welding shielding gas, the molten pool will naturally collapse downwards. At the same time, some metal will be carried away by evaporation or spatter during welding, which will aggravate the collapse of the molten pool.

[0007] Chinese patent application CN202410259265.7 discloses a laser welding method for reducing keyhole collapse, comprising: S1, forming a first welding beam, wherein the first welding beam is displaced relative to the material along a preset welding path to form a keyhole in the material; S2, forming a second welding beam, wherein the second welding beam acts on the rear wall of the keyhole to maintain the opening stability of the keyhole; wherein the power of the second welding beam is less than or equal to the power of the first welding beam.

[0008] The aforementioned prior art uses a first welding beam with high energy and a large spot size to overcome the initial resistance caused by the poor absorption properties of the material, thereby achieving high absorption efficiency laser welding. A second welding beam is formed after the first welding beam. The second welding beam acts on the rear wall of the keyhole, changing the flow state of the molten pool on the rear wall of the keyhole and slowing down the fluid kinetic energy of the liquid metal located on the rear wall of the keyhole.

[0009] However, the aforementioned existing technology only maintains the keyhole opening stability through multiple beams, but when the laser energy is suddenly turned off at the end of the welding, it will still cause the keyhole to close rapidly and form a hole. In addition, the end molten pool in the existing technology is prone to collapse due to the lack of welding wire compensation. Summary of the Invention

[0010] The purpose of this invention is to provide a handheld laser welding system and method that avoids the collapse of the filler wire welding end, thereby partially solving or alleviating the above-mentioned deficiencies in the prior art.

[0011] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution: A first aspect of the present invention is to provide a handheld laser welding system for preventing collapse of the filler wire welding tip, comprising: Laser drive module, used to excite the welding laser.

[0012] Motor oscillation controller, used to control the oscillation of the welding laser; The wire feed controller is used to control wire feeding and drawing. An optical control module is used to control the change of the welding laser focus; Welding machine controller, used to control the welding laser power; After sending the welding end command, proceed to the filling phase: The welding machine controller is configured to control the welding laser power excited by the laser drive module to decrease from p to p1 within time t1 and continue for time t2. The wire feed controller is configured to control the wire feed speed to decrease from v to v1 after time t3 and continue for time t4 before decreasing to 0, where t3+t4=t1 and t1 and t3 start at the same time. The motor swing controller is configured to control the swing amplitude of the welding laser to decrease from D to 0 within time t1. The optical control module is configured to control the welding laser spot to a first shape when welding to the edge of the weld, to a third shape when welding to the center of the weld, and to control the welding laser spot to a second shape when welding between the edge and the center of the weld. After the filling stage ends, the wire breakage stage begins: The wire feed controller is configured to perform wire drawing after time t2 ends; and during time t2, the optical control module is configured to control the welding laser spot to act on the welding wire in a fourth mode. The diameter of the first morphological spot d1 > the diameter of the second morphological spot d2 > the diameter of the third morphological spot d3 > the diameter of the third morphological spot d4.

[0013] Furthermore, the laser driving module includes a collimation module and a reflector located on the optical path of the collimation module, the reflector being able to reflect the laser calibrated by the collimation module.

[0014] Furthermore, the optical control module includes a focusing mirror that can move back and forth along the laser light path reflected by the mirror under the drive of the driving mechanism, and the focusing mirror is located behind the mirror.

[0015] Furthermore, the optical control module includes a collimating lens that moves back and forth along the collimating module optical path under the drive of the driving mechanism, and a focusing lens located on the laser optical path reflected by the reflecting mirror.

[0016] Furthermore, the driving mechanism includes a motor module, and the focusing lens or collimating lens is threadedly connected to the output end of the motor module, so that the focusing lens or collimating lens moves back and forth when the motor module rotates forward and backward.

[0017] Furthermore, the welding machine controller has built-in power parameters, which include power descent time t1, power sustaining time t2, and sustaining power p1; The wire feeding controller has built-in wire feeding parameters, which include a first wire feeding duration t3, a second wire feeding duration t4, and a duration speed v1. The motor swing controller has built-in swing parameters, including the power descent time t1. The command to stop welding is simultaneously sent to the welding machine controller, the wire feed controller, and the motor swing controller. After receiving the command to stop welding, the welding machine controller, the wire feed controller, and the motor swing controller automatically call the power parameters, wire feed parameters, and swing parameters for control, respectively.

[0018] Furthermore, the welding machine controller calculates the power drop point Δp per unit time based on the current power p, the sustained power p1, and the power descent time t1; The motor swing controller calculates the swing amplitude point ΔD per unit time based on the current swing amplitude D and the power descent time t1.

[0019] The present invention also provides a method for avoiding end collapse of filler wire welds, applied to the above-mentioned handheld laser welding system, comprising: Upon receiving a stop welding command, the filling phase begins. During the filling phase, the welding laser power decreases from p to p1 within time t1 and continues for time t2. The wire feed speed decreases from v to v1 after time t3 and continues for time t4 before decreasing to 0, where t3 + t4 = t1 and t1 and t3 start at the same time. The oscillation amplitude of the welding laser decreases from D to 0 within time t1. The welding laser focus is controlled so that when welding reaches the edge of the weld, the welding laser spot is in the first form; when welding reaches the center of the weld, the welding laser spot is in the third form; and when welding between the edge and the center of the weld, the welding laser spot is in the second form. After the filling stage ends, the wire breaking stage begins; the wire breaking stage is performed by drawing the wire after time t2 ends; and during time t2, the welding laser spot is controlled to act on the welding wire in the fourth mode. The diameter of the first morphological spot d1 > the diameter of the second morphological spot d2 > the diameter of the third morphological spot d3 > the diameter of the third morphological spot d4.

[0020] Furthermore, a power descent process was added to the conventional welding scheme for several experiments. The power descent time was increased in each experiment until the arc-end crater no longer decreased with the increase of time, thereby determining t1. Set the wire feeding speed v1 to 0, and pre-set t3 to t1. Gradually decrease t3 for testing until the welding wire can be fully melted without the phenomenon of non-melting wire, thus determining t3. t4 = t1 - t3; Based on t4, the stepped wire feeding speed is continuously adjusted to ensure that the welding wire can be fully melted and filled, thereby determining v1.

[0021] Furthermore, p1 is 8-12% of the maximum rated power; t2 is determined by testing the melting time of the welding wire based on the power p1.

[0022] The beneficial effects of this invention are as follows: This invention eliminates end-sinking in traditional welding by coordinating power reduction, narrowing of the oscillation, and stepped wire feeding. Through a combination of low power, minimal spot size, and precise wire drawing, it eliminates wire sticking defects, significantly reducing the end-sinking defect rate. The graded spot switching adapts to the weld edge, transition, and center regions; low energy at the edges prevents undercut, high energy at the center ensures penetration, and the transition region exhibits smooth energy flow without abrupt changes, significantly improving weld uniformity and fusion quality.

[0023] Each module uses the stop welding command as a unified trigger point. Power, wire feed, and oscillation share a common time reference t1. Linear calculations of Δp and ΔD ensure dynamic matching of energy space, avoiding defects caused by timing misalignment. Welding quality is unaffected by operator experience. Each controller has built-in optimized parameters, eliminating the need for manual adjustment. Stable and consistent welding results can be output regardless of different equipment or operators. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0025] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the laser driving module and the optical control module in Embodiment 1 of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the laser driving module and the optical control module in another embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram illustrating the effect of changing the position of the focusing lens on different light spots.

[0028] Figure 5 A comparison of the spot size at different weld locations.

[0029] Figure 6 This is a power-time diagram.

[0030] Figure 7 This is a diagram showing the wire feeding speed versus time.

[0031] Figure 8 This is a schematic diagram of the swing amplitude versus time.

[0032] Figure 9 This is a schematic diagram of the drawing process and the time involved.

[0033] Summary of attached labeling and identification: 1. Focusing lens, 2. Mounting base, 3. Motor module, 4. Collimating lens; 101. Collimating module, 102. Reflecting mirror. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In this document, suffixes such as "module," "part," or "unit" used to denote elements are used only for the purpose of illustrative purposes and have no specific meaning in themselves. Therefore, "module," "part," or "unit" may be used interchangeably.

[0036] In this document, the terms "upper," "lower," "inner," "outer," "front," "rear," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In this document, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] In this document, "and / or" includes any and all combinations of one or more of the listed related items.

[0039] In this article, "multiple" means two or more, that is, it includes two, three, four, five, etc.

[0040] Example 1: like Figure 1 As shown, this embodiment provides a handheld laser welding system to avoid end collapse in filler wire welding, comprising: 1. Laser drive module, used to excite the welding laser.

[0041] Specifically, such as Figure 2 As shown, the laser driving module excites and outputs the laser beam required for welding. In this embodiment, the laser driving module includes a laser (not shown), a collimation module 101, and a reflector 102 located on the optical path of the collimation module. The reflector 102 can reflect the laser beam calibrated by the collimation module 101. When the laser beam is output from the laser, it will naturally diverge due to the diffraction effect at the end face of the optical fiber. Direct transmission would lead to energy dispersion and beam enlargement. The collimation module 101 consists of a set of high-precision lenses. Through the refraction of the lenses, the diverging light rays are refracted into parallel light rays, ensuring that the laser energy is concentrated and the beam size is stable during transmission.

[0042] The reflector 102 is used to change the direction of the light path, adapt to the structural layout of the handheld welding torch, and turn the laser from the horizontal or vertical direction to the surface of the workpiece.

[0043] 2. Motor oscillation controller, used to control the oscillation of the welding laser.

[0044] The motor swing controller controls the swing trajectory and amplitude of the laser beam, expanding the energy coverage of the welding area and adapting to the needs of welds of different widths.

[0045] The wire feed controller is used to control wire feeding and drawing. It controls the wire feeding speed and drawing action. Wire feeding refers to the continuous feeding of metal welding wire, such as stainless steel or aluminum wire, into the weld pool via a wire feeding mechanism. During laser welding, the molten metal in the pool is lost due to evaporation and spatter; wire feeding replenishes the metal, ensuring a full weld and preventing depressions. Wire drawing is the action of quickly pulling the welding wire out of the molten pool at the end of welding, preventing the wire from sticking to the solidified molten pool and ensuring the wire can easily detach from the base material.

[0046] An optical control module is used to control the change in the welding laser focus. For example... Figure 2 As shown, in some embodiments, the optical control module includes a focusing mirror 1 that can move back and forth along the laser light path reflected by the reflector 102 under the drive of the driving mechanism. The focusing mirror 1 is located behind the reflector 102. The reflector 102 is located upstream and first reflects the parallel laser output from the collimation module 101. The focusing mirror 1 is located behind the light path of the reflector 102, meaning that the reflected laser beam will directly enter the focusing mirror 1, forming a complete optical path of laser, collimation module 101, reflector 102, focusing mirror 1, and workpiece.

[0047] The core function of focusing lens 1 is to adjust the diameter and energy density of the laser spot by changing the distance from the workpiece, i.e., the focal point.

[0048] For a collimated parallel laser, the focal length f of focusing lens 1 is fixed. According to the focusing characteristics of Gaussian beams, the spot diameter d is related to the distance L from focusing lens 1 to the workpiece. When focusing lens 1 moves forward, L decreases, the laser focus falls on the workpiece surface, the spot diameter is the smallest, and the energy density is the highest, which is suitable for the center position of the weld. When focusing lens 1 moves backward, the focus is located above the workpiece, the spot diameter formed by the laser on the workpiece surface increases, and the energy density decreases, which is suitable for the edge position of the weld.

[0049] Through precise control of the drive mechanism, the position change of the focusing lens 1 can be accurately converted into graded adjustment of the spot diameter, achieving the quantitative target of reducing the edge energy by 45%-55% compared to the center, and the switching response time is ≤100ms to meet the dynamic requirements of handheld welding.

[0050] like Figure 3 As shown, in some other embodiments, the optical control module includes a collimating lens 4 that moves back and forth along the optical path of the collimating module 101 under the drive of the driving mechanism, and a focusing lens 1 located on the laser optical path reflected by the reflecting mirror 102.

[0051] The collimating lens 4 is located in the optical path of the collimating module 101 near the laser output end and can move back and forth along the optical axis. The reflecting mirror 102 is located downstream of the collimating lens's optical path, receiving the beam adjusted by the collimating lens and changing its direction. The focusing mirror 4 is fixed on the reflected optical path of the reflecting mirror 102, ultimately focusing the beam onto the workpiece surface. This forms a complete optical path consisting of the laser, the movable collimating lens 4, the reflecting mirror 102, the fixed focusing mirror 4, and the workpiece.

[0052] This method adjusts the collimation position of the front end. Compared to adjusting the focusing lens, its algorithm is more complex. However, since the optical axial magnification is a square relationship, only a short position change is needed to adjust the focus, which reduces the response speed.

[0053] In both methods, the driving mechanism includes a motor module, and the focusing lens 1 or collimating lens 4 is threadedly connected to the output end of the motor module 3, so that the focusing lens 1 or collimating lens 4 moves back and forth when the motor module 3 rotates forward and backward.

[0054] The output end of the motor module is typically a precision ball screw or trapezoidal screw, which forms a threaded pair with the mounting base 2 of the lens (collimating lens or focusing lens). When the motor module rotates forward, the output end rotates, and the mounting base 2 moves forward along the optical axis; when rotating in reverse, the mounting base 2 moves backward.

[0055] like Figure 4 As shown, taking the adjustment of the focusing lens position as an example, the change of the focusing lens position is the core adjustment point. The focusing lens in different positions corresponds to different welding areas and spot shapes.

[0056] When the laser is positioned at the edge of the weld, the focusing lens is moved back away from the workpiece. At this time, the laser focus deviates from the workpiece surface, and the spot diameter formed on the workpiece is the largest and the energy density is the lowest. This is used in the weld edge area to avoid excessive energy causing undercut damage to the base material.

[0057] During the transition phase, the focusing lens is in the middle position, the spot diameter is between the edge and the center, and the energy density is moderate. This is used in the transition area between the edge and the center of the weld to achieve a smooth energy transition and avoid step-like changes in weld width.

[0058] When the laser is positioned at the center of the weld, the focusing lens is moved forward and close to the workpiece, ensuring that the laser focus is precisely on the workpiece surface. This results in the smallest spot diameter and the highest energy density, making it ideal for the central area of ​​the weld and guaranteeing that the penetration depth meets the requirements.

[0059] Figure 5 The image shows the size of the laser spot at different locations on the weld. Spots 1 and 5 represent the weld edge. These spots have the largest diameter, with energy gradually decreasing from the center to the edge (achieving a 45%-55% reduction in energy at the edge compared to the center), preventing undercut defects caused by excessive energy at the weld edge. Spots 2 and 4 represent the transitional state between the edge and center. With spot diameters between the edge and center, the energy distribution transitions more smoothly, ensuring no abrupt changes in weld width and depth from the edge to the center, improving weld consistency. Spot 3 represents the weld center. This spot has the smallest diameter, with energy highly concentrated in the central area, ensuring the weld depth meets standards at the center.

[0060] The welding machine controller is used to control the welding laser power. The welding machine controller does more than simply output laser power; it focuses on suppressing end-effector collapse and wire sticking defects from the energy source through dynamic power adjustment, in conjunction with wire feeding, oscillation, and spot control.

[0061] More specifically, the method for solving the end-collapse problem using the aforementioned handheld laser welding system involves entering the filling phase after sending the welding end command: The welding machine controller described in S101 is configured to control the welding laser power excited by the laser drive module to decrease from p to p1 within time t1 and continue for time t2.

[0062] Laser power p is the conventional power during the welding process, used to maintain a stable molten pool and ensure that the weld penetration reaches the required level.

[0063] p1 is the low holding power, typically 8-12% of the maximum rated power, used at the end of the fill stage and the wire breakage stage. The energy is only enough to maintain the fluidity of the molten pool or melt the tip of the welding wire to prevent over-melting of the base material.

[0064] Time t1 is the power descent time, which is the total time from p to p1.

[0065] Time t2 is the low power sustaining time, which is the duration of p1, covering the wire breakage stage and ensuring that the tip of the welding wire is fully melted.

[0066] like Figure 6 As shown, the power p linearly decreases to p1 in stage t1 to leave sufficient energy window for filling, avoiding rapid solidification of the molten pool due to a sudden drop in power, and ensuring that the molten pool maintains sufficient fluidity throughout the wire feeding and filling process.

[0067] At the end of welding, if the power drops instantly from p to 0, the molten pool will rapidly cool and shrink due to the loss of energy support. At this time, the metal replenished by the wire feed cannot fill the shrinkage space in time, which can easily lead to collapse. Linear gradual descent, by controlling the power decrease per unit time Δp=(p-p1) / t1, makes the temperature gradient of the molten pool decrease steadily.

[0068] The power in stage t2 is maintained at p1, providing precise energy for wire breakage, ensuring that only the tip of the welding wire is melted and separated from the molten pool, while avoiding secondary defects in the base material due to excessive energy.

[0069] After the filling stage is completed, a wire-pulling action is required to remove the welding wire from the molten pool. If the power is 0 at this time, the unmelted tip of the welding wire is prone to sticking to the solidified molten pool; if the power is too high, it will over-melt the base material and form a pit. The energy of p1 is just right.

[0070] The wire feeding controller S102 is configured to control the wire feeding speed to decrease from v to v1 after time t3 and continue for time t4 before decreasing to 0, where t3+t4=t1 and t1 and t3 start at the same time.

[0071] v represents the normal wire feed speed during the welding process, used to continuously replenish the molten pool metal and ensure a full weld.

[0072] v1 is a low wire feed speed in the later stage of the filling phase, which is adapted to the shrinkage of the molten pool after the power decreases.

[0073] t3 is the time during which the wire feeding speed is maintained at v.

[0074] t4 is the time it takes for the wire feeding speed to decrease from v to v1 and remain there, eventually decreasing to 0.

[0075] The formula t3+t4=t1 ensures that the total time t1 for power descent and oscillation narrowing is perfectly matched, and that t3 and t1 start at the same time, both starting from the welding end command.

[0076] like Figure 7 As shown, the state of the molten pool during the filling stage t1 changes continuously as the power decreases and the oscillation narrows. In the early stage, the power is high and the oscillation amplitude is large, the molten pool volume is large and the fluidity is strong, requiring more metal replenishment. In the later stage, the power drops to P1 and the oscillation amplitude narrows to 0, the molten pool volume shrinks and the fluidity weakens, requiring a reduction in metal replenishment.

[0077] During the t3 phase, maintain rapid wire feed at speed v to prevent initial collapse. In the early stages of the filling phase, ensure the molten pool has sufficient metal to meet the demands before the power drops significantly and while the pool remains relatively active. In the first t3 period after welding, the laser power remains high, the oscillation amplitude is large, and the molten pool maintains a large volume and fluidity due to ample energy. If the wire feed speed drops suddenly at this point, insufficient metal replenishment will occur, leading to initial collapse of the molten pool due to its own contraction. Therefore, maintaining the original speed v allows for rapid metal replenishment, reserving filling space for subsequent contraction.

[0078] In stage t4, the speed is reduced to v1 and eventually stopped. During the later stages of the filling phase, the wire feed rate is reduced as the molten pool shrinks to prevent excessive metal buildup or over-melting. Upon entering stage t4, the laser power and oscillation amplitude decrease significantly, and the molten pool volume shrinks as energy decreases, reducing metal consumption. If v is maintained at this point, the wire feed rate will exceed the molten pool's needs, leading to excess metal buildup and weld beads. Therefore, reducing the speed to v1 and then to 0 at the end of t1 achieves a precise balance between molten pool shrinkage and metal replenishment.

[0079] The motor swing controller described in S103 is configured to control the swing amplitude of the welding laser to decrease from D to 0 within time t1.

[0080] D represents the oscillation amplitude of the laser during the welding process, which is used to expand the welding area and ensure the width and fusion of the weld.

[0081] t1 is consistent with the time base of power descent and is the total time for the swing amplitude to decrease from D to 0.

[0082] The laser beam gradually narrows from oscillating left and right to cover the wide weld seam, and then focuses on the center of the weld seam, achieving a natural arc termination at the end of the weld seam. This avoids excessively wide ends or edge biting caused by the oscillation not stopping, and ensures that the final laser spot falls on the welding wire, which facilitates wire reeling in the later stage.

[0083] The welding end needs to smoothly transition from the wide weld seam to the arc termination point. If the oscillation amplitude suddenly drops from D to 0, the edge area will cool too quickly due to the sudden withdrawal of the laser, resulting in undercut or incomplete fusion. The central area will have over-melting pits due to the sudden concentration of the laser and excess energy.

[0084] like Figure 8 As shown, linear narrowing is achieved by controlling the decrease in the swing amplitude per unit time ΔD=D / t1, so that the weld width naturally narrows as the swing amplitude decreases.

[0085] In the initial stage, the oscillation amplitude is still relatively large, which is suitable for the stage with higher power to ensure that the edge area is fully fused; in the later stage, the oscillation amplitude gradually narrows, which is suitable for the stage with lower power to avoid excess energy in the central area.

[0086] The optical control module described in S104 is configured to control the welding laser spot in a first shape when welding to the edge of the weld, in a third shape when welding to the center of the weld, and in a second shape when welding between the edge and the center of the weld. The diameter d1 of the first shape spot is greater than the diameter d2 of the second shape spot, which is greater than the diameter d3 of the third shape spot.

[0087] The three types of light spots achieve graded control of energy density through differences in diameter. It is worth noting that energy density is inversely proportional to the diameter of the light spot.

[0088] The first mode, located at the weld edge, has the largest spot diameter and the lowest energy density, with the energy density reduced by 45%-55% compared to the center. It is used in the weld edge area to avoid excessive energy leading to undercut. The second mode, located at the transition between the edge and the center, has a spot diameter between the first and third modes and a moderate energy density. It is used in the transition area from the weld edge to the center to achieve a smooth energy transition and avoid step-like changes in weld width.

[0089] The third mode, located at the center of the weld, has the smallest spot diameter and the highest energy density. It is used in the center area of ​​the weld to ensure that the penetration depth meets the requirements.

[0090] When the first morphological spot is at the edge, the power is in the gradual decrease stage. The combination of large spot and low power further reduces the edge energy and completely avoids edge biting. Corresponding to the t4 stage of the wire feeding speed, the metal supply is reduced to avoid accumulation.

[0091] In the third-mode spot at the center, although the power decreases, the spot size is small, and the energy density is still sufficient to maintain the melting depth. The voltage (v) is maintained during the t3 stage corresponding to the wire feed speed to ensure sufficient metal filling in the central molten pool.

[0092] The switching of the light spot shape is matched with the rhythm of the oscillation amplitude decay. When the oscillation amplitude narrows to the center, the light spot switches to the third shape in sync, and the energy is concentrated in the center to achieve precise melting depth at the arc termination point.

[0093] It is worth noting that steps S101 to S104 are performed synchronously according to their respective timelines, without any order.

[0094] After the filling stage ends, the wire breakage stage begins: The wire feed controller described in S201 is configured to perform wire drawing after time t2 ends; and during time t2, the optical control module is configured to control the welding laser spot to act on the welding wire in a fourth form; the diameter of the first form spot d1 > the diameter of the second form spot d2 > the diameter of the third form spot d3 > the diameter of the third form spot d4.

[0095] like Figure 9As shown, after the filling stage ends, the low power p1 is maintained for a time t2 (when the time ends), the wire feed controller drives the wire feed mechanism to quickly retract the welding wire to ensure that the tip of the welding wire can quickly detach from the solidified molten pool after melting, thus avoiding welding wire sticking due to cooling and solidification.

[0096] During time t2, i.e., the low-power p1 maintenance phase, the optical control module switches the laser spot to the fourth mode, whose diameter d4 is the smallest of all modes, and it is precisely focused on the tip of the welding wire, melting only the tip of the welding wire and avoiding over-melting of the base material due to an excessively large spot. Combined with low-power p1, this achieves precise control of energy to melt the wire without damaging the base material.

[0097] In this embodiment, the welding machine controller has built-in power parameters, which include power descent time t1, power maintenance time t2, and maintenance power p1.

[0098] The wire feeding controller has built-in wire feeding parameters, which include a first wire feeding duration t3, a second wire feeding duration t4, and a duration speed v1.

[0099] The motor swing controller has built-in swing parameters, including the power descent time t1.

[0100] The command to stop welding is simultaneously sent to the welding machine controller, the wire feed controller, and the motor swing controller. After receiving the command to stop welding, the welding machine controller, the wire feed controller, and the motor swing controller automatically call the power parameters, wire feed parameters, and swing parameters for control, respectively.

[0101] This system employs a unified starting point and separate execution control logic. When the system issues a stop welding command, the command is simultaneously sent to all three controllers, ensuring that the start times of all end-effector actions—power reduction, wire feed deceleration, and oscillation narrowing—are completely consistent. This avoids timing misalignments caused by command transmission delays in traditional control systems. Furthermore, due to the unique nature of its control, the optical control module requires a separately configured trigger signal.

[0102] In addition, the welding machine controller calculates the power drop point Δp per unit time based on the current power p, the sustained power p1, and the power descent time t1; the calculation formula is Δp=(p p1) / t1.

[0103] If the power decrease is nonlinear, it can cause abrupt changes in the molten pool temperature gradient. Rapid cooling in the early stages may result in insufficient melting of the metal supplied by the wire feed, while slow cooling in the later stages may lead to over-melting and collapse of the molten pool. A linear distribution of Δp, however, allows the molten pool temperature to decrease steadily over time, providing stable energy for the stepped replenishment of the wire feed.

[0104] The motor swing controller calculates the swing amplitude ΔD per unit time based on the current swing amplitude D and the power reduction time t1. The calculation formula is: ΔD = D / t1.

[0105] Linear narrowing ensures that the weld width decreases uniformly over time, avoiding stepped welds caused by sudden changes in amplitude.

[0106] Example 2: The present invention also provides a method for avoiding end collapse of filler wire welds, applied to the above-mentioned handheld laser welding system, comprising: S1 enters the filling stage after receiving the command to stop welding; in the filling stage, the welding laser power decreases from p to p1 within time t1 and lasts for time t2; the wire feed speed decreases from v to v1 after time t3 and lasts for time t4 before decreasing to 0, t3+t4=t1 and t1 and t3 start at the same time; the oscillation amplitude of the welding laser decreases from D to 0 within time t1; the welding laser focus is controlled so that when welding to the edge of the weld, the welding laser spot is in the first form, when welding to the center of the weld, the welding laser spot is in the third form, and when welding between the edge and the center of the weld, the welding laser spot is in the second form. S2 enters the wire breakage stage after the filling stage ends; the wire breakage stage is the wire pulling after time t2 ends; and during time t2, the welding laser spot is controlled to act on the welding wire in the fourth form; The diameter of the first morphological spot d1 > the diameter of the second morphological spot d2 > the diameter of the third morphological spot d3 > the diameter of the third morphological spot d4.

[0107] In addition, this embodiment also provides a method for obtaining the above parameters, the specific steps of which include: S301 added a power descent process to the conventional welding scheme and conducted several experiments. In each experiment, the power descent time was increased until the arc-end crater no longer decreased with the increase of time, thus determining t1.

[0108] If t1 is too short, the energy of the molten pool will decrease sharply and the pool will not be filled. If t1 is too long, there will be no gain. We need to find a critical value where the marginal benefit is zero.

[0109] Welding is completed using standard welding parameters: power p, wire feed speed v, and oscillation amplitude D. At the end, a process is added where the power gradually decreases from p to p1. p1 is preset to 8-12% of the rated power.

[0110] In the first experiment, t1 was set to a small value, such as 100 ms, and the depth of the arc-end crater was recorded. In each subsequent experiment, the t1 time was increased by 50 ms each time, and the welding was repeated while measuring the crater depth. The optimal t1 value was defined as the difference in crater depth between two consecutive experiments being ≤0.02 mm, indicating that the crater no longer decreased with increasing t1.

[0111] The essence of t1 is the buffer time for the energy decay of the molten pool. A sufficiently long t1 allows the molten pool to fully receive wire feeding and filling as the energy gradually decreases; however, once the critical value is exceeded, the molten pool is already completely filled, and extending t1 further will only increase the welding time without any practical benefit.

[0112] S302 sets the wire feeding holding speed v1 to 0, and pre-sets t3 to t1, and gradually reduces t3 for testing until the welding wire can be fully melted without the phenomenon of unmelted wire, thus determining t3.

[0113] t3 is the time during which the wire feeding speed is maintained at v. If it is too long, it will lead to insufficient energy in the molten pool later. If it is too short, it will lead to insufficient filling in the initial stage. It is necessary to find the shortest t3 with no unmelted wire.

[0114] Set the time t1 determined by S301 to 0, and set the wire feeding speed v1 to 0. Initially, t3 = t1, that is, maintain the wire feeding speed v throughout the entire process.

[0115] In the first experiment, since t3=t1, the power has been reduced to p1 in the later stage, and the wire feeding speed is still v, which may result in the welding wire not melting completely. In each experiment, t3 is reduced by 20ms each time, which means entering the stage of slowing down to 0 earlier. When the welding wire is completely melted in the experiment and there is no initial collapse, t3 is the optimal value.

[0116] t3 needs to be matched with the high energy stage at the beginning of the filling process. At this time, the molten pool has sufficient energy and can quickly receive the metal supply at a high wire feed speed v. However, as the power decreases, if v is maintained, the welding wire will not be able to melt due to insufficient energy. Therefore, t3 needs to be shortened and the speed reduced in advance.

[0117] S303 t4=t1-t3.

[0118] t4 is the time window from when the wire feeding speed drops from v to v1 and finally stops. Its length is determined by t1 and t3 together, ensuring that the wire feeding speed reduction rhythm is perfectly aligned with the time axis of power reduction and oscillation narrowing.

[0119] S304 continuously adjusts the stepped wire feeding speed according to t4 to ensure that the welding wire can be fully melted and filled, thereby determining v1.

[0120] V1 is the wire feeding speed in stage t4. It needs to be matched with the low power at this time. If it is too high, it will cause metal accumulation (weld bead), and if it is too low, it will cause insufficient filling. A speed that is just right needs to be found.

[0121] Fix t1, t3, and t4, i.e., the values ​​determined by S301-S303. Initially set v1 to a low value, such as 30% of v. Gradually increase v1, such as increasing v by 5% each time, and observe the end filling effect. When the welding wire is completely melted in the t4 stage, the molten pool is fully filled and there is no metal accumulation, v1 at this time is the optimal value.

[0122] In stage t4, the power has dropped to p1, and the volume of the molten pool shrinks as energy decreases. V1 needs to match the amount of metal consumed by the molten pool at this time. Lower energy means slower consumption, so V1 needs to be lower than the normal speed v to ensure that the wire feed rate matches the amount of metal consumed by the molten pool.

[0123] S305 states that p1 is 8-12% of the maximum rated power; t2 is determined by testing the melting time of the welding wire based on the power p1.

[0124] t2 is the duration of p1's continuous action. It needs to work in conjunction with p1 to ensure that the tip of the welding wire has been fully melted before wire drawing.

[0125] Set the t1 determined by S301, the wire feeding parameters determined by S302-S304, and the preset p1; in the first experiment, set t2 to a small value, such as 50ms, and observe the state of the welding wire after executing the wire breakage process. If t2 is too short, the tip of the welding wire will not be completely melted, and the wire will easily stick when pulling it out; in each experiment, increase t2, such as +20ms each time, and repeat the test to observe whether a molten ball is formed at the tip of the welding wire, and at the same time check whether there are traces of over-melting in the base material; when the tip of the welding wire forms a round molten ball that can be smoothly removed from the molten pool, and there is no over-melting in the base material, t2 is the optimal value.

[0126] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0127] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a computer terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0128] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A handheld laser welding system for preventing end collapse in filler wire welding, characterized in that... include: The laser drive module is used to excite the welding laser; Motor oscillation controller, used to control the oscillation of the welding laser; The wire feed controller is used to control wire feeding and drawing. An optical control module is used to control the change of the welding laser focus; Welding machine controller, used to control the welding laser power; After sending the welding end command, proceed to the filling stage: The welding machine controller is configured to control the welding laser power excited by the laser drive module to decrease from p to p1 within time t1 and continue for time t2. The wire feed controller is configured to control the wire feed speed to decrease from v to v1 after time t3 and continue for time t4 before decreasing to 0, where t3+t4=t1 and t1 and t3 start at the same time. The motor swing controller is configured to control the swing amplitude of the welding laser to decrease from D to 0 within time t1. The optical control module is configured to control the welding laser spot to a first shape when welding to the edge of the weld, to a third shape when welding to the center of the weld, and to control the welding laser spot to a second shape when welding between the edge and the center of the weld. After the filling stage ends, the wire breakage stage begins: The wire feed controller is configured to perform wire drawing after time t2 ends; and during time t2, the optical control module is configured to control the welding laser spot to act on the welding wire in a fourth form. The diameter of the first morphological spot d1 > the diameter of the second morphological spot d2 > the diameter of the third morphological spot d3 > the diameter of the third morphological spot d4.

2. The handheld laser welding system for avoiding end collapse of filler wire welding according to claim 1, characterized in that: The laser driving module includes a collimation module and a reflector located on the optical path of the collimation module. The reflector can reflect the laser calibrated by the collimation module.

3. A handheld laser welding system for avoiding end collapse of filler wire welding according to claim 2, characterized in that: The optical control module includes a focusing mirror that can move back and forth along the laser light path reflected by the mirror under the drive of the driving mechanism, and the focusing mirror is located behind the mirror.

4. A handheld laser welding system for avoiding end collapse of filler wire welding according to claim 2, characterized in that: The optical control module includes a collimating lens that moves back and forth along the optical path of the collimating module under the drive of the driving mechanism, and a focusing lens located on the laser optical path reflected by the reflecting mirror.

5. A handheld laser welding system for avoiding end collapse of filler wire welding according to claim 3 or 4, characterized in that: The drive mechanism includes a motor module, and the focusing lens or collimating lens is threadedly connected to the output end of the motor module, so that the focusing lens or collimating lens moves back and forth when the motor module rotates forward and backward.

6. A handheld laser welding system for avoiding end collapse of filler wire welding according to claim 1, characterized in that: The welding machine controller has built-in power parameters, which include power descent time t1, power sustaining time t2, and sustaining power p1. The wire feeding controller has built-in wire feeding parameters, which include a first wire feeding duration t3, a second wire feeding duration t4, and a duration speed v1. The motor swing controller has built-in swing parameters, including the power descent time t1. The welding stop command is simultaneously sent to the welding machine controller, wire feed controller, and motor swing controller. After receiving the welding stop command, the welding machine controller, wire feed controller, and motor swing controller will automatically call the power parameters, wire feed parameters, and swing parameters for control.

7. A handheld laser welding system for avoiding end collapse of filler wire welding according to claim 6, characterized in that: The welding machine controller calculates the power drop point Δp per unit time based on the current power p, the sustained power p1, and the power descent time t1; The motor swing controller calculates the swing amplitude point ΔD per unit time based on the current swing amplitude D and the power descent time t1.

8. A method for preventing collapse at the end of filler wire welding, applied to the handheld laser welding system according to any one of claims 1 to 7, characterized in that... include: Upon receiving a stop welding command, the filling phase begins; during the filling phase, the welding laser power decreases from p to p1 within time t1 and continues for time t2. The wire feed speed decreases from v to v1 after time t3 and continues for time t4 before decreasing to 0. t3 + t4 = t1, and t1 and t3 start at the same time. The oscillation amplitude of the welding laser decreases from D to 0 within time t1. The welding laser focus is controlled so that when welding to the edge of the weld, the welding laser spot is in the first state; when welding to the center of the weld, the welding laser spot is in the third state; and when welding between the edge and the center of the weld, the welding laser spot is in the second state. After the filling stage ends, the wire breaking stage begins; the wire breaking stage is performed by drawing the wire after time t2 ends; and during time t2, the welding laser spot is controlled to act on the welding wire in the fourth mode. The diameter of the first morphological spot d1 > the diameter of the second morphological spot d2 > the diameter of the third morphological spot d3 > the diameter of the third morphological spot d4.

9. A method for avoiding collapse at the end of filler wire welding according to claim 8, characterized in that: Several experiments were conducted by adding a power descent process to the conventional welding scheme. In each experiment, the power descent time was increased until the arc crater no longer decreased with the increase of time, thereby determining t1. Set the wire feeding speed v1 to 0, and pre-set t3 to t1. Gradually decrease t3 for testing until the welding wire can be fully melted without the phenomenon of non-melting wire, thus determining t3. t4 = t1 - t3; Based on t4, the stepped wire feeding speed is continuously adjusted to ensure that the welding wire can be fully melted and filled, thereby determining v1.

10. A method for avoiding collapse at the end of filler wire weld according to claim 9, characterized in that: p1 is 8-12% of the maximum rated power; The melting time of the welding wire is determined by testing the power p1 to determine t2.

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