Constant-speed laser welding method based on S track

Abstract

The invention discloses a constant-speed laser welding method based on an S track. The constant-speed laser welding method comprises the following steps that S1, track planning is conducted; s2, speed setting; s3, performing real-time control; s4, dynamic parameter adjustment: in the step S1, the length and width of a welding seam are designed based on the welding area required by welding overflowing to generate a parameterized S track, the smooth connection of adjacent curve sections is ensured, in the step S1, a welding path is formed by a continuous and smooth S curve, the mathematical expression of the S curve is a segmented cubic Bezier curve or a parameterized equation, and the linear equation is a linear equation; in the step S2, a constant speed value is calculated according to the influence of material heat capacity and welding heat and a key hole forming mechanism of a welding pool, and through collaborative optimization of S track design and a speed control algorithm, the problem that the penetration depth is not uniform due to sudden change of the speed of a traditional sine track is fundamentally solved; and the method has remarkable technical advancement and industrial application value.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy batteries and laser welding processes, and particularly to a constant-speed laser welding method based on an "S" trajectory. Background Art

[0002] In traditional welding processes, a sine wave trajectory (such as a "Z" shape or a wavy path) is often used for weld filling or penetration welding. The speed at the turning inflection points of such trajectories approaches zero, leading to the following problems: 1. Heat accumulation: The speed decreases at the inflection points, resulting in concentrated heat input, which easily causes over-welding, burn-through, or material deformation. 2. Inconsistent penetration depth: The speed fluctuations cause significant differences in the penetration depth of different regions of the weld, affecting the structural strength. 3. Low efficiency: Frequent acceleration and deceleration increase the welding time and reduce the production efficiency. The prior art alleviates the above problems by adjusting the speed and energy through a control card or by adjusting the path amplitude and scanning speed through a galvanometer scanner, but does not fundamentally solve the defects caused by the coupling of the trajectory and speed. Summary of the Invention

[0003] Based on the technical problems in the background art, namely heat accumulation: the speed decreases at the inflection points, resulting in concentrated heat input, which easily causes over-welding, burn-through, or material deformation; inconsistent penetration depth: the speed fluctuations cause significant differences in the penetration depth of different regions of the weld, affecting the structural strength; low efficiency: frequent acceleration and deceleration increase the welding time and reduce the production efficiency, the present invention proposes a constant-speed laser welding method based on an "S" trajectory.

[0004] The constant-speed laser welding method based on an "S" trajectory proposed by the present invention includes the following steps: S1: Trajectory planning; S2: Speed setting; S3: Real-time control; S4: Dynamic parameter adjustment.

[0005] Preferably, in the S1 step, a parameterized "S" trajectory is generated based on the welding area required for welding overcurrent, designing the weld length and width, ensuring smooth connection of adjacent curve segments.

[0006] Preferably, in the S1 step, the welding path is composed of continuous and smooth "S" curves, and its mathematical expression is a piecewise cubic Bezier curve or a parametric equation, ensuring continuous change of the curvature radius at the inflection points and avoiding sharp turns.

[0007] Preferably, in the S2 step, the constant speed value is calculated according to the material heat capacity, the welding heat influence, and the formation mechanism of the "keyhole" in the welding molten pool, avoiding overheating or too fast cooling of the molten pool.

[0008] Preferably, in the step S2, the trajectory moves along an "S" trajectory at a preset constant speed, and the galvanometer scanning speed is dynamically adjusted through a real-time feedback control system to eliminate the instantaneous heat input fluctuation caused by acceleration and deceleration.

[0009] Preferably, in the step S3, the laser welding position is controlled by a control card and a galvanometer, and the angles of the motor and the reflecting mirror inside the galvanometer are closed-loop controlled to maintain a constant linear speed.

[0010] Preferably, in the step S4, according to the molten pool temperature fed back by the infrared thermal imager, the trajectory amplitude or the welding energy is finely adjusted to compensate for the environmental heat loss.

[0011] Preferably, in the step S4, according to the material thickness, thermal conductivity and weld width, the amplitude and period of the "S" trajectory are adaptively adjusted to match the constant speed to achieve the best heat distribution.

[0012] Advantages of the present invention: 1. Improvement in the consistency of the weld penetration: The uniform motion makes the heat input per unit length constant, and the fluctuation range of the weld penetration is reduced to ±5% (±15% in the traditional process); 2. Reduction in the defect rate: There is no sudden change in speed at the inflection point, and the over-welding rate is reduced by more than 60%; 3. Optimization of the efficiency: There is no need for frequent acceleration and deceleration, and the welding time is shortened by about 20%; 4. The welding trajectory has no inflection point, and the welding process has good consistency; 5. The welding speed has good consistency and is more suitable for the adjustment of the production line speed; 6. The thermal influence is small, and there is no heat melting of the diaphragm; 7. The amplitude and period of the "S" trajectory can be dynamically adjusted according to the weld width and material thermal conductivity; Through the collaborative optimization of the "S" trajectory design and the speed control algorithm, the present invention fundamentally solves the problem of uneven weld penetration caused by sudden speed changes in the traditional sine trajectory, and has significant technological progressiveness and industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the "S" welding wire proposed by the present invention; Figure 2 It is a schematic diagram of the heat melting of the diaphragm proposed by the present invention; Figure 3 It is a working flow chart proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The present invention will be further explained below with reference to specific embodiments.

[0015] Refer to Figures 1-3 , Embodiment 1 In this embodiment, a constant-speed laser welding method based on the "S" trajectory is proposed, including the following steps: S1: Trajectory planning. Design the weld length and width based on the welding area required for overcurrent to generate a parameterized "S" trajectory, ensuring smooth connection of adjacent curve segments. The welding path consists of continuous and smooth "S" curves, and its mathematical expression is a piecewise cubic Bezier curve or a parametric equation, ensuring continuous change of the curvature radius at the inflection point to avoid sharp turns; S2: Speed setting. Calculate the constant speed value according to the material heat capacity, welding heat influence, and the formation mechanism of the "keyhole" in the welding molten pool to avoid overheating or too fast cooling of the molten pool. The trajectory moves along the "S" trajectory at a preset constant speed, and dynamically adjusts the galvanometer scanning speed through a real-time feedback control system to eliminate the instantaneous heat input fluctuation caused by acceleration and deceleration; S3: Real-time control. Control the laser welding position through a control card and a galvanometer, and use a closed-loop control to maintain a constant linear speed for the motor and the angle of the internal reflection lens in the galvanometer; S4: Dynamic parameter adjustment. Fine-tune the trajectory amplitude or welding energy according to the molten pool temperature feedback by an infrared thermal imager to compensate for environmental heat loss. Adaptively adjust the amplitude and period of the "S" trajectory according to the material thickness, thermal conductivity, and weld width, and match the constant speed to achieve the best heat distribution.

[0016] Parameter setting: Curve height 10 mm, curve width 2 mm, speed 700 mm / s, energy 700 W; Result: (1) The fluctuation range of the weld penetration is optimized from 1.2 - 1.8 mm in the traditional process to 1.5 - 1.6 mm, and there are no visible over-welding defects.

[0017] (2) The hot melting of the diaphragm is optimized from 1 mm of hot melting in the traditional process to 0, and there is no hot melting of the diaphragm and no short-circuit risk.

[0018] Refer to Figures 1-3 , Embodiment 2 In this embodiment, a constant-speed laser welding method based on the "S" trajectory is proposed, including the following steps: S1: Trajectory planning. Design the weld length and width based on the welding area required for overcurrent to generate a parameterized "S" trajectory, ensuring smooth connection of adjacent curve segments. The welding path consists of continuous and smooth "S" curves, and its mathematical expression is a piecewise cubic Bezier curve or a parametric equation, ensuring continuous change of the curvature radius at the inflection point to avoid sharp turns; S2: Speed setting. Calculate the constant speed value according to the material heat capacity, welding heat influence, and the formation mechanism of the "keyhole" in the welding molten pool to avoid overheating or too fast cooling of the molten pool. The trajectory moves along the "S" trajectory at a preset constant speed, and dynamically adjusts the galvanometer scanning speed through a real-time feedback control system to eliminate the instantaneous heat input fluctuation caused by acceleration and deceleration; S3: Real-time control, controlling the laser welding position through the control card and galvanometer, and maintaining a constant linear velocity by means of closed-loop control of the motor and the angle of the reflecting mirror inside the galvanometer; S4: Dynamic parameter adjustment, fine-tuning the trajectory amplitude or welding energy according to the molten pool temperature feedback by the infrared thermal imager to compensate for environmental heat loss, and adaptively adjusting the amplitude and period of the "S" trajectory according to the material thickness, thermal conductivity and weld width to match a constant speed to achieve the best heat distribution.

[0019] Parameter setting: curve amplitude height 10mm, curve amplitude width 2mm, speed 300mm / s, energy 500W; Result: The weld width consistency reaches 98%, and the width of the heat affected zone is reduced by 30%.

[0020] As mentioned above, it is only the preferred specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A constant speed laser welding method based on an "S" trajectory, characterized in that, It includes the following steps: S1: Trajectory planning; S2: Speed setting; S3: Real-time control; S4: Dynamic parameter adjustment.

2. The constant speed laser welding method based on the "S" trajectory according to claim 1, wherein In the S1 step, a parametric "S" trajectory is generated by designing the weld length and width based on the welding area required for overcurrent welding, ensuring smooth connection of adjacent curve segments.

3. The constant-speed laser welding method based on the "S" trajectory according to claim 1, characterized in that, In the S1 step, the welding path is composed of continuous smooth "S" curves, and its mathematical expression is a piecewise cubic Bezier curve or a parametric equation, ensuring continuous change of the curvature radius at the inflection point to avoid sharp turns.

4. The constant speed laser welding method based on the "S" trajectory according to claim 1, characterized in that In the S2 step, the constant speed value is calculated according to the material heat capacity, welding heat influence and the formation mechanism of the "keyhole" in the welding molten pool to avoid overheating or too fast cooling of the molten pool.

5. The constant speed laser welding method based on the "S" trajectory according to claim 1, characterized in that, In the S2 step, the trajectory moves along the "S" trajectory at a preset constant speed, and the galvanometer scanning speed is dynamically adjusted through a real-time feedback control system to eliminate the instantaneous heat input fluctuation caused by acceleration and deceleration.

6. The constant-speed laser welding method based on the "S" trajectory according to claim 1, characterized in that, In the S3 step, the laser welding position is controlled by a control card and a galvanometer, and the closed-loop control is used to keep the angles of the motor and the internal reflection mirror in the galvanometer constant to maintain a constant linear speed.

7. The constant speed laser welding method based on the "S" trajectory according to claim 1, characterized in that, In the S4 step, according to the molten pool temperature feedback by the infrared thermal imager, the trajectory amplitude or welding energy is finely adjusted to compensate for environmental heat loss.

8. The constant speed laser welding method based on the "S" trajectory according to claim 1, characterized in that, In the S4 step, according to the material thickness, thermal conductivity and weld width, the amplitude and period of the "S" trajectory are adaptively adjusted to match the constant speed to achieve the best heat distribution.

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